Reduced mRNA abundance of the main enzymes involved in methionine metabolism in human liver cirrhosis and hepatocellular carcinoma.
Avila MA, Berasain C, Torres L, et al.
J Hepatol. 2000 Dec; 33(6):907-14.
BACKGROUND/AIMS: It has been known for at least 50 years that alterations in methionine metabolism occur in human liver cirrhosis. However, the molecular basis of this alteration is not completely understood. In order to gain more insight into the mechanisms behind this condition, mRNA levels of methionine adenosyltransferase (MAT1A), glycine methyltransferase (GNMT), methionine synthase (MS), betaine homocysteine methyltransferase (BHMT) and cystathionine beta-synthase (CBS) were examined in 26 cirrhotic livers, five hepatocellular carcinoma (HCC) tissues and ten control livers. METHODS: The expression of the above-mentioned genes was determined by quantitative RT-PCR analysis. Methylation of MAT1A promoter was assessed by methylation-sensitive restriction enzyme digestion of genomic DNA. RESULTS: When compared to normal livers MAT1A, GNMT, BHMT, CBS and MS mRNA contents were significantly reduced in liver cirrhosis. Interestingly, MAT1A promoter was hypermethylated in the cirrhotic liver. HCC tissues also showed decreased mRNA levels of these enzymes. CONCLUSIONS: These findings establish that the abundance of the mRNA of the main genes involved in methionine metabolism is markedly reduced in human cirrhosis and HCC. Hypermethylation of MAT1A promoter could participate in its reduced expression in cirrhosis. These observations help to explain the hypermethioninemia, hyperhomocysteinemia and reduced hepatic glutathione content observed in cirrhosis
Structure-function relationships of the dietary anticarcinogen ellagic acid.
Barch DH, Rundhaugen LM, Stoner GD, et al.
Carcinogenesis. 1996 Feb; 17(2):265-9.
Ellagic acid is a complex planar molecule which demonstrates a variety of anticarcinogenic activities. Ellagic acid has been shown to inhibit the CYP1A1-dependent activation of benzo[a]pyrene; to bind to and detoxify the diolepoxide of benzo[a]pyrene; to bind to DNA and reduce the formation of O6-methylguanine by methylating carcinogens; and to induce the phase II detoxification enzymes glutathione S-transferase Ya and NAD(P)H:quinone reductase. Chemical analogs of ellagic acid were synthesized to examine the relationship between the hydroxyl and lactone groups of the ellagic acid molecule and its different anticarcinogenic activities. These studies demonstrated that both the 3-hydroxyl and the 4-hydroxyl groups were required for ellagic acid to directly detoxify the diolepoxide of benzo[a]pyrene, while only the 4-hydroxyl groups were necessary for ellagic acid to inhibit CYP1A1-dependent benzo[a]pyrene hydroxylase activity. Induction of glutathione S-transferase Ya and NAD(P):quinone reductase required the lactone groups of ellagic acid, but the hydroxyl groups were not required for the induction of these phase II enzymes. In addition, the lactone groups, but not the hydroxyl groups, were required for the analogs to reduce the carcinogen-induced formation of O6-methylguanine. Thus, different portions of the ellagic acid molecule are responsible for its different putative anticarcinogenic activities
Dietary supplement with vitamin C prevents nitrate tolerance.
Bassenge E, Fink N, Skatchkov M, et al.
J Clin Invest. 1998 Jul 1; 102(1):67-71.
Enhanced formation of superoxide radicals has been proposed to play a major role in the development of nitrate tolerance in humans. We tested the effects of vitamin C (Vit-C) supplementation on glyceroltrinitrate (GTN)-induced hemodynamic effects during 3-d nonintermittent transdermal administration of GTN (0.4 mg/h) in nine healthy subjects. Tolerance development was monitored by changes in arterial pressure, dicrotic digital pulse pressure, and heart rate. Studies with GTN, Vit-C, or GTN/Vit-C were successively carried out at random in three different series in the same subjects. GTN treatment caused an immediate rise in arterial conductivity (a/b ratio of dicrotic pulse), but within 2 d of initiating GTN, the a/b ratio progressively decreased and reached basal levels. In addition, there was a progressive loss of the orthostatic decrease in blood pressure. However, coadministration of Vit-C and GTN fully maintained the GTN-induced changes in the orthostatic blood pressure, and the rise of a/b ratio was augmented by 310% for the duration of the test period. Changes in vascular tolerance in GTN-treated subjects were paralleled by upregulation of the activity of isolated platelets, which was also reversed by Vit-C administration. These findings demonstrate that dietary supplementation with Vit-C eliminates vascular tolerance and concomitant upregulation of ex vivo-washed platelet activity during long-term nonintermittent administration of GTN in humans
Green tea constituent (--)-epigallocatechin-3-gallate inhibits topoisomerase I activity in human colon carcinoma cells.
Berger SJ, Gupta S, Belfi CA, et al.
Biochem Biophys Res Commun. 2001 Oct 19; 288(1):101-5.
DNA topoisomerases I and II are essential for cell survival and play critical roles in DNA metabolism and structure. Inhibitors of topoisomerase constitute a novel family of antitumor agents with demonstrated clinical activity in human malignancies. The clinical use of these agents is limited due to severe toxic effects on normal cells. Therefore, there is a need to develop novel, nontoxic topoisomerase inhibitors that have the ability to spare normal cells. Recent studies have shown that green tea and its major polyphenolic constituent, epigallocatechin-3-gallate (EGCG), impart growth inhibitory responses to cancer cells but not to normal cells. Based on the knowledge that EGCG induces DNA damage, cell cycle arrest, and apoptosis, we considered the possibility of the involvement of topoisomerase in the antiproliferative response of EGCG. Here, for the first time, we show that EGCG inhibits topoisomerase I, but not topoisomerase II in several human colon carcinoma cell lines. Based on this study it is tempting to suggest that combination of EGCG with other conventional topoisomerase inhibitors could be an improved strategy for treatment of colon cancer. The possible role of EGCG as a chemotherapeutic agent needs to be investigated
Selected novel flavones inhibit the DNA binding or the DNA religation step of eukaryotic topoisomerase I.
Boege F, Straub T, Kehr A, et al.
J Biol Chem. 1996 Jan 26; 271(4):2262-70.
Topoisomerases are involved in many aspects of DNA metabolism such as replication and transcription reactions. Camptothecins, which stabilize the covalent intermediate of topoisomerase I and DNA are effective, though toxic, drugs for cancer therapy. In this study, a new class of topoisomerase I inhibitors was identified, and their mode of action was characterized using recombinant human topoisomerase I preparations and human HL-60 leukemic cells. Quercetin and the related natural flavones, acacetin, apigenin, kaempferol, and morin, inhibit topoisomerase I-catalyzed DNA religation. In contrast to camptothecin, these compounds do not act directly on the catalytic intermediate and also do not interfere with DNA cleavage. However, formation of a ternary complex with topoisomerase I and DNA during the cleavage reaction inhibits the following DNA religation step. 3,3',4',7-Tetrahydroxy-substituted flavones stabilize the covalent topoisomerase I-DNA intermediate most efficiently. Enhanced formation of covalent topoisomerase I-DNA complexes was also demonstrated in human HL-60 cells. In contrast, synthetic 3,5'-dibromo- 4'-hydroxy-3-methylflavones bind selectively to topoisomerase I in its non-DNA-bound form and block the following DNA binding step. As a consequence, these synthetic flavonoids are capable of counteracting topoisomerase I-directed effects of camptothecin. Inhibition of DNA binding is obtained by voluminous hydrophobic substituents in 6-position of the flavone structure. Our data show that selective inhibitors of both half-reactions of topoisomerase I can be derived from the flavone structure
Combined effects of lipid peroxidation and antioxidant status on carotid atherosclerosis in a population aged 59-71 y: The EVA Study. Etude sur le Vieillisement Arteriel.
Bonithon-Kopp C, Coudray C, Berr C, et al.
Am J Clin Nutr. 1997 Jan; 65(1):121-7.
There are few epidemiologic studies of the effects of lipid peroxidation and antioxidant status on atherosclerosis. The relation of lipid peroxidation evaluated by thiobarbituric acid-reactive substances (TBARS) and biological markers of antioxidant status to ultrasonographically assessed carotid atherosclerosis was examined from baseline data of a longitudinal study on cognitive and vascular aging (Etude sur le Vieillisement Arteriel, the EVA Study). The study sample was composed of 1187 mean and women aged 59-71 y without any history of coronary artery disease or stroke. Ultrasound examination included measurements of intima-media thickness (IMT) on the common carotid arteries (CCAs) and at the site of plaques. After adjustment for conventional cardiovascular risk factors, erythrocyte vitamin E was significantly and negatively associated with CCA-IMT in both men and women whereas plasma selenium and carotenoids were not. No association was found between TBARS and CCA-IMT in either sex. However, TBARS were significantly higher in men with carotid plaques than in those without. This association was strengthened in men with concentrations of erythrocyte vitamin E, plasma selenium, and carotenoids below the lowest quartile. Our findings give some epidemiologic support to the hypothesis that lipid peroxidation and low antioxidant status are involved in the early phases of atherosclerosis
Increased plasma homocysteine in liver cirrhosis.
Bosy-Westphal A, Petersen S, Hinrichsen H, et al.
Hepatol Res. 2001 May 1; 20(1):28-38.
Background: Homocysteine (Hcy), is an atherogenic and thrombogenic risk factor which has also been proposed to be involved in hepatic fibrinogenesis. Hcy metabolism, depends on the cofactors folate, vit. B12, and the vit. B6 vitamer pyridoxalphosphate (PLP). Metabolism of these vitamins is frequently disturbed in cirrhotics, but little is known about plasma Hcy levels in these patients. Methods: Plasma levels of Hcy, methionine, serine, cysteine, PLP, vit. B12 and folate, and standard clinical/biochemical parameters of liver disease were measured in 43 postabsorptive patients with biopsy proven cirrhosis of different origin. Results: 74% of the patients had elevated plasma Hcy levels defined as >13.4 micromol/l (mean+2SD of healthy age matched controls). Increased plasma Hcy concentrations were seen in alcoholic as well as in non-alcoholic cirrhosis. Excluding patients with impaired renal function (n=7), Hcy concentrations remained elevated in 69% of the patients. We found a high prevalence of pathological plasma vitamin concentrations of 33% for increased vit. B12 levels and 5% and 80% for decreased folate and vit. B6 levels, respectively. Mean plasma vitamin B12 concentrations increased, folate remained unchanged and PLP concentrations decreased with deteriorating liver function. Hcy concentrations were correlated with levels of creatinine (r=0.44, P<0.01), serine (r=-0.46, P<0.01), and cysteine (r=0.38, P<0.05), but showed no association with parameters of liver function and with plasma levels of folate, vit. B12 und vit. B6. This was contrary to data obtained in healthy individuals. In a stepwise multiple regression serine and cysteine best explained the variance in Hcy levels. Conclusions: Elevated basal Hcy-plasma levels are frequently seen cirrhotic patients. Variations of Hcy concentration in liver cirrhosis are not explained by plasma levels of cofactors of Hcy metabolism
Calcium, physical activity and bone health--building bones for a stronger future.
Branca F, Valtuena S, Vatuena S.
Public Health Nutr. 2001 Feb; 4(1A):117-23.
Adequate provision of nutrients composing the bone matrix and regulating bone metabolism should be provided from birth in order to achieve maximal bone mass, compatible with individual genetic background, and to prevent osteoporosis later in life. Low calcium intake (<250 mg day(-1)) in children is associated with both a reduced bone mineral content and hyperparathyroidism. Optimal calcium intake is, however, still a matter of controversy. The minimisation of fracture risk would be the ideal functional outcome on which to evaluate lifetime calcium intakes, but proxy indicators, such as bone mass measurements or maximal calcium retention, are used instead. Calcium recommendations in Europe and the United States are based on different concepts as to requirements, leading to somewhat different interpretations of dietary adequacy. Minerals and trace elements other than calcium are involved in skeletal growth, some of them as matrix constituents, such as magnesium and fluoride, others as components of enzymatic systems involved in matrix turnover, such as zinc, copper and manganese. Vitamins also play a role in calcium metabolism (e.g. vitamin D) or as co-factors of key enzymes for skeletal metabolism (e.g. vitamins C and K). Physical activity has different effects on bone depending on its intensity, frequency, duration and the age at which it is started. The anabolic effect on bone is greater in adolescence and as a result of weight-bearing exercise. Adequate intakes of calcium appear necessary for exercise to have its bone stimulating action
Nutrient intake in relation to bladder cancer among middle-aged men and women.
Bruemmer B, White E, Vaughan TL, et al.
Am J Epidemiol. 1996 Sep 1; 144(5):485-95.
This population-based case-control study examined the association between selected nutrients, foods, and diet behaviors and bladder cancer. Bladder cancer cases (n = 262) were identified from the Surveillance, Epidemiology, and End Results Program cancer registry for western Washington, and controls (n = 405) were identified through random digit dialing. Cases were diagnosed between January 1987 and June 1990, and eligible subjects were Caucasian, aged 45-65 years, and residents of King, Pierce, or Snohomish counties. Subjects completed a self-administered, 71-item food frequency questionnaire and a structured telephone interview. Analyses were conducted by logistic regression analysis and included adjustment for age, sex, smoking (current, former, never), and county. Odds ratios and their 95% confidence intervals for highest versus lowest level of intake were examined. An inverse association was found between the risk of bladder cancer and dietary retinol (odds ratio (OR) across quartiles: 1.00, 1.09, 0.97, and 0.52; 95% CI 0.29-0.97; trend p value = 0.03) and dietary vitamin C (OR across quartiles: 1.00, 0.96, 0.67, and 0.50; 95% CI 0.28-0.88; trend p value = 0.009), adjusted for calories. The use of multivitamin supplements daily over the 10-year period ending 2 years before diagnosis versus no use was associated with a decreased risk of bladder cancer (OR = 0.39; 95% CI 0.24-0.63) as was use of supplemental vitamin C (OR for > 502 mg/day over the 10 years vs. none = 0.40; 95% CI 0.21-0.76). Increased intake of fruit was associated with a decreased risk of bladder cancer (OR across quartiles: 1.00, 1.24, 0.72, and 0.53; 95% CI 0.30-0.93; trend p value = 0.01, adjusted for calories), while increased use of fried foods was associated with an increased risk of bladder cancer (OR across quartiles: 1.00, 1.51, 1.81, and 2.24; 95% CI 1.25-4.03; trend p value = 0.006). This study provides modest evidence that certain nutrients, foods, and supplementation may affect the incidence of bladder cancer
Demonstration of rapid onset vascular endothelial dysfunction after hyperhomocysteinemia: an effect reversible with vitamin C therapy.
Chambers JC, McGregor A, Jean-Marie J, et al.
Circulation. 1999 Mar 9; 99(9):1156-60.
BACKGROUND: Hyperhomocysteinemia is a major and independent risk factor for vascular disease. The mechanisms by which homocysteine promotes atherosclerosis are not well understood. We hypothesized that elevated homocysteine concentrations are associated with rapid onset endothelial dysfunction, which is mediated through oxidant stress mechanisms and can be inhibited by the antioxidant vitamin C. Methods and RESULTS: We studied 17 healthy volunteers (10 male and 7 female) aged 33 (range 21 to 59) years. Brachial artery diameter responses to hyperemic flow (endothelium dependent), and glyceryltrinitrate (GTN, endothelium independent) were measured with high resolution ultrasound at 0 hours (fasting), 2 hours, and 4 hours after (1) oral methionine (L-methionine 100 mg/kg), (2) oral methionine preceded by vitamin C (1g/day, for 1 week), and (3) placebo, on separate days and in random order. Plasma homocysteine increased (0 hours, 12.8+/-1.4; 2 hours, 25.4+/-2.5; and 4 hours, 31. 2+/-3.1 micromol/l, P<0.001), and flow-mediated dilatation fell (0 hours, 4.3+/-0.7; 2 hours, 1.1+/-0.9; and 4 hours, -0.7+/-0.8%) after oral L-methionine. There was an inverse linear relationship between homocysteine concentration and flow-mediated dilatation (P<0. 001). Pretreatment with vitamin C did not affect the rise in homocysteine concentrations after methionine (0 hours, 13.6+/-1.6; 2 hours, 28.3+/-2.9; and 4 hours, 33.8+/-3.7 micromol/l, P=0.27), but did ameliorate the reduction in flow-mediated dilatation (0 hours, 4. 0+/-1.0; 2 hours, 3.5+/-1.2 and 4 hours, 2.8+/-0.7%, P=0.02). GTN-induced endothelium independent brachial artery dilatation was not affected after methionine or methionine preceded by vitamin C. CONCLUSIONS: We conclude that an elevation in homocysteine concentration is associated with an acute impairment of vascular endothelial function that can be prevented by pretreatment with vitamin C in healthy subjects. Our results support the hypothesis that the adverse effects of homocysteine on vascular endothelial cells are mediated through oxidative stress mechanisms
Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. A randomized controlled trial. Nutritional Prevention of Cancer Study Group.
Clark LC, Combs GF, Jr., Turnbull BW, et al.
JAMA. 1996 Dec 25; 276(24):1957-63.
OBJECTIVE: To determine whether a nutritional supplement of selenium will decrease the incidence of cancer. DESIGN: A multicenter, double-blind, randomized, placebo-controlled cancer prevention trial. SETTING: Seven dermatology clinics in the eastern United States. PATIENTS: A total of 1312 patients (mean age, 63 years; range, 18-80 years) with a history of basal cell or squamous cell carcinomas of the skin were randomized from 1983 through 1991. Patients were treated for a mean (SD) of 4.5 (2.8) years and had a total follow-up of 6.4 (2.0) years. INTERVENTIONS: Oral administration of 200 microg of selenium per day or placebo. MAIN OUTCOME MEASURES: The primary end points for the trial were the incidences of basal and squamous cell carcinomas of the skin. The secondary end points, established in 1990, were all-cause mortality and total cancer mortality, total cancer incidence, and the incidences of lung, prostate, and colorectal cancers. RESULTS: After a total follow-up of 8271 person-years, selenium treatment did not significantly affect the incidence of basal cell or squamous cell skin cancer. There were 377 new cases of basal cell skin cancer among patients in the selenium group and 350 cases among the control group (relative risk [RR], 1.10; 95% confidence interval [CI], 0.95-1.28), and 218 new squamous cell skin cancers in the selenium group and 190 cases among the controls (RR, 1.14; 95% CI, 0.93-1.39). Analysis of secondary end points revealed that, compared with controls, patients treated with selenium had a nonsignificant reduction in all-cause mortality (108 deaths in the selenium group and 129 deaths in the control group [RR; 0.83; 95% CI, 0.63-1.08]) and significant reductions in total cancer mortality (29 deaths in the selenium treatment group and 57 deaths in controls [RR, 0.50; 95% CI, 0.31-0.80]), total cancer incidence (77 cancers in the selenium group and 119 in controls [RR, 0.63; 95% CI, 0.47-0.85]), and incidences of lung, colorectal, and prostate cancers. Primarily because of the apparent reductions in total cancer mortality and total cancer incidence in the selenium group, the blinded phase of the trial was stopped early. No cases of selenium toxicity occurred. CONCLUSIONS: Selenium treatment did not protect against development of basal or squamous cell carcinomas of the skin. However, results from secondary end-point analyses support the hypothesis that supplemental selenium may reduce the incidence of, and mortality from, carcinomas of several sites. These effects of selenium require confirmation in an independent trial of appropriate design before new public health recommendations regarding selenium supplementation can be made
Botanical derivatives for the prostate.
Cristoni A, Di Pierro F, Bombardelli E.
Fitoterapia. 2000 Aug; 71 Suppl 1:S21-S28.
The prostate, after the age of 45 years, may undergo benign hyperplasia (BPH). Its etiology has not yet been completely explained, but different factors play a major role in its occurrence, among them, the sexual hormones (with a fundamental role of 5 alpha reductase). The 5-alpha reductase activity and inflammatory aspects in the prostate tissue can be effectively controlled with the use of highly standardized plant extracts (Pygeum africanum, Serenoa repens, etc.), which yield excellent results in the prophylaxis and treatment of the symptoms linked to prostate hypertrophy. The prostate tissue is not affected only by benign diseases but may also be subject to neoplastic transformation. From an epidemiological point of view, a vegetable derivative, lycopene, was linked with a lower occurrence of prostate carcinoma. A recent clinical study demonstrated that lycopene might not only prevent prostate cancer but also have therapeutic effects
Intake of vitamins B6 and C and the risk of kidney stones in women.
Curhan GC, Willett WC, Speizer FE, et al.
J Am Soc Nephrol. 1999 Apr; 10(4):840-5.
Urinary oxalate is an important determinant of calcium oxalate kidney stone formation. High doses of vitamin B6 may decrease oxalate production, whereas vitamin C can be metabolized to oxalate. This study was conducted to examine the association between the intakes of vitamins B6 and C and risk of kidney stone formation in women. The relation between the intake of vitamins B6 and C and the risk of symptomatic kidney stones were prospectively studied in a cohort of 85,557 women with no history of kidney stones. Semiquantitative food-frequency questionnaires were used to assess vitamin consumption from both foods and supplements. A total of 1078 incident cases of kidney stones was documented during the 14-yr follow-up period. A high intake of vitamin B6 was inversely associated with risk of stone formation. After adjusting for other dietary factors, the relative risk of incident stone formation for women in the highest category of B6 intake (> or =40 mg/d) compared with the lowest category (<3 mg/d) was 0.66 (95% confidence interval, 0.44 to 0.98). In contrast, vitamin C intake was not associated with risk. The multivariate relative risk for women in the highest category of vitamin C intake (> or =1500 mg/d) compared with the lowest category (<250 mg/d) was 1.06 (95% confidence interval, 0.69 to 1.64). Large doses of vitamin B6 may reduce the risk of kidney stone formation in women. Routine restriction of vitamin C to prevent stone formation appears unwarranted
Advanced glycation endproducts change glutathione redox status in SH-SY5Y human neuroblastoma cells by a hydrogen peroxide dependent mechanism.
Deuther-Conrad W, Loske C, Schinzel R, et al.
Neurosci Lett. 2001 Oct 12; 312(1):29-32.
The reaction of proteins with reducing sugars leads to the formation of 'advanced glycation endproducts' (AGEs). They accumulate in Alzheimer's disease brain in the vicinity of beta-amyloid plaques. AGEs are cytotoxic by a mechanism involving reactive oxygen species, which implies that they could compromise glutathione redox status. In this study, we show that AGEs (BSA-AGE and beta-amyloid-AGE) persistently increase the ratio of oxidized to reduced glutathione in a dose- and time-dependent manner in SH-SY5Y neuroblastoma cells. The level of oxidized glutathione accounted to 10-14% and persisted for up to 24 h in the presence of added AGEs. In contrast, the unmodified beta-amyloid peptides A beta (1-40) and A beta (25-35) had no significant effect on glutathione redox status. The AGE-induced increase in oxidized glutathione could be prevented by the radical scavengers N-acetylcysteine, alpha-lipoic acid and 17beta-estradiol or by application of catalase, indicating that superoxide and hydrogen peroxide production precedes the AGE-mediated depletion of reduced glutathione
Exercise intolerance and the mitochondrial respiratory chain.
Ital J Neurol Sci. 1999 Dec; 20(6):387-93.
The syndrome of exercise intolerance, cramps, and myoglobinuria is a common presentation of metabolic myopathies and has been associated with several specific inborn errors of glycogen or lipid metabolism. As disorders in fuel utilization presumably impair muscle energy production, it was more than a little surprising that exercise intolerance and myoglobinuria had not been associated with defects in the mitochondrial respiratory chain, the terminal energy-yielding pathway. Recently, however, specific defects in complex I, complex III, and complex IV have been identified in patients with severe exercise intolerance with or without myoglobinuria. All patients were sporadic cases and all harbored mutations in protein-coding genes of muscle mtDNA, suggesting that these were somatic mutations not affecting the germ-line. Another respiratory chain defect, primary coenzyme Q10 (CoQ10) deficiency, also causes exercise intolerance and recurrent myoglobinuria, usually in conjunction with brain symptoms, such as seizures or cerebellar ataxia. Primary CoQ10 deficiency is probably due to mutations in nuclear gene(s) encoding enzymes involved in CoQ10 biosynthesis
Role of calcium, vitamin D, and other essential nutrients in the prevention and treatment of osteoporosis.
Nurs Clin North Am. 2001 Sep; 36(3):417-31, viii.
Calcium is an essential nutrient for the prevention and treatment of osteoporosis. Despite universal recognition of its importance, most people still do not obtain recommended amounts. Recent additions to the treatment of osteoporosis with potent bone active drugs produce an even greater need for calcium and total nutrition for restoration of lost bone. Practitioners and patients need to emphasize and appreciate the role that calcium, vitamin D, and other nutrients play in the promotion of health and in the prevention and treatment of disease
Effect of calcium glucarate on beta-glucuronidase activity and glucarate content of certain vegetables and fruits.
Dwivedi C, Heck WJ, Downie AA, et al.
Biochem Med Metab Biol. 1990 Apr; 43(2):83-92.
Glucarate is normally present in tissues and body fluids and is in equilibrium with D-glucaro-1,4-lactone, a natural inhibitor of beta-glucuronidase activity. Dietary calcium glucarate, a sustained-release from of glucarate, elevates the blood level of D-glucaro-1,4-lactone which suppresses blood and tissue beta-glucuronidase activity. A single dose of CaG (4.5 mmole/kg body weight) inhibited beta-glucuronidase activity in serum and liver, lung, and intestinal microsomes by 57, 44, 37, and 39%, respectively. A chronic administration of calcium glucarate (4% in diet) also decreased beta-glucuronidase activity in intestinal and liver microsomes. Maximal inhibition of beta-glucuronidase activity in serum was observed from 12 noon to 2:00 PM. In contrast, maximum inhibition of beta-glucuronidase activity in intestinal and liver microsomes occurred during mornings, although a secondary depression in intestinal microsomes also occurred around 4 PM. A 4% calcium glucarate supplemented diet also inhibited beta-glucuronidase activity by 70% and 54%, of the bacterial flora obtained from proximal (small intestine) and distal (colon) segments of intestine, respectively. Due to the potential effect of dietary glucarate on net glucuronidation and on other metabolic pathways, glucaric acid levels in various foods were determined. The glucaric acid content varied from a low of 1.12-1.73 mg/100 g for broccoli and potatoes to a high of 4.53 mg/100 g for oranges
Vitamin C intake and mortality among a sample of the United States population.
Enstrom JE, Kanim LE, Klein MA.
Epidemiology. 1992 May; 3(3):194-202.
We examined the relation between vitamin C intake and mortality in the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study cohort. This cohort is based on a representative sample of 11,348 noninstitutionalized U.S. adults age 25-74 years who were nutritionally examined during 1971-1974 and followed up for mortality (1,809 deaths) through 1984, a median of 10 years. An index of vitamin C intake has been formed from detailed dietary measurements and use of vitamin supplements. The relation of the standardized mortality ratio (SMR) for all causes of death to increasing vitamin C intake is strongly inverse for males and weakly inverse for females. Among those with the highest vitamin C intake, males have an SMR (95% confidence interval) of 0.65 (0.52-0.80) for all causes, 0.78 (0.50-1.17) for all cancers, and 0.58 (0.41-0.78) for all cardiovascular diseases; females have an SMR of 0.90 (0.74-1.09) for all causes, 0.86 (0.55-1.27) for all cancers, and 0.75 (0.55-0.99) for all cardiovascular diseases. Comparisons are made relative to all U.S. whites, for whom the SMR is defined to be 1.00. There is no clear relation for individual cancer sites, except possibly an inverse relation for esophagus and stomach cancer among males. The relation with all causes of death among males remains after adjustment for age, sex, and 10 potentially confounding variables (including cigarette smoking, education, race, and disease history)
Dose-related preventive and therapeutic effects of antioxidants-anticarcinogens on experimentally induced malignant tumors in Wistar rats.
Evangelou A, Kalpouzos G, Karkabounas S, et al.
Cancer Lett. 1997 May 1; 115(1):105-11.
A combination of antioxidants-anticarcinogens, consisting of vitamins C and E, selenium and 2-mercaptopropionyl glycine (2-MPG), was administered orally for the prevention (PRG) and treatment (TRG) of benzo(a)pyrene (BaP)-induced malignant tumors (leiomyosarcomas), in Wistar rats. In order to evaluate dose-related effects, a low dose vitamin (0.15 g/kg b.w. per day of vit.C and 0.05 g/kg b.w. per day of vit.E) and a high dose (1.5 g/kg b.w. per day of vit.C and 0.5 g/kg b.w. per day of vit.E) combination was administered, in prevention and treatment groups. Selenium was administered in doses of 2 microg/kg b.w. per day and 2-MPG in 15 mg/kg b.w. per day, in all groups. Daily estimations of 24 h urine volume levels of thiobarbituric acid reacting substances (MDA) were performed in 20 animals, divided into a control group, a BaP-injected group, a tricapryline-injected group and a BaP-injected and treated by the low dose combination group. Results revealed that the low dose combination failed to exert any beneficial effect on mean survival time of animals treated either preventitively or therapeutically. An increased number of animals bearing a second (lung) tumor was, in addition, found in autopsy and histological examination in the low dose combination (PRG and TRG) and the high dose TRG groups. The high dose combination groups manifested a significant prolongation of the mean survival time of animals; complete remission of tumors developed in 16.8% of the animals in the treatment group and a 5.2% prevention of tumor formation in the preventive group, without any evidence of an increased number of double tumor formation in the PRG group. Urine MDA increased significantly in animals injected by BaP during the first 10 days and since the 90th day (formation of palpable tumors) after injection, in relation to control and tricapryline-injected groups. Complete prevention of urine MDA-increased values was obtained in BaP-injected and treated by the low dose combination animals. Results indicate that high doses (megadoses) of the antioxidant-anticarcinogen vitamins C and E in combination with carefully selected other antioxidants possessing supplementary actions, are probably needed in order to achieve a sufficient prevention and treatment of malignant diseases
Vitamins for chronic disease prevention in adults: scientific review.
Fairfield KM, Fletcher RH.
JAMA. 2002 Jun 19; 287(23):3116-26.
CONTEXT: Although vitamin deficiency is encountered infrequently in developed countries, inadequate intake of several vitamins is associated with chronic disease. OBJECTIVE: To review the clinically important vitamins with regard to their biological effects, food sources, deficiency syndromes, potential for toxicity, and relationship to chronic disease. DATA SOURCES AND STUDY SELECTION: We searched MEDLINE for English-language articles about vitamins in relation to chronic diseases and their references published from 1966 through January 11, 2002. DATA EXTRACTION: We reviewed articles jointly for the most clinically important information, emphasizing randomized trials where available. DATA SYNTHESIS: Our review of 9 vitamins showed that elderly people, vegans, alcohol-dependent individuals, and patients with malabsorption are at higher risk of inadequate intake or absorption of several vitamins. Excessive doses of vitamin A during early pregnancy and fat-soluble vitamins taken anytime may result in adverse outcomes. Inadequate folate status is associated with neural tube defect and some cancers. Folate and vitamins B(6) and B(12) are required for homocysteine metabolism and are associated with coronary heart disease risk. Vitamin E and lycopene may decrease the risk of prostate cancer. Vitamin D is associated with decreased occurrence of fractures when taken with calcium. CONCLUSIONS: Some groups of patients are at higher risk for vitamin deficiency and suboptimal vitamin status. Many physicians may be unaware of common food sources of vitamins or unsure which vitamins they should recommend for their patients. Vitamin excess is possible with supplementation, particularly for fat-soluble vitamins. Inadequate intake of several vitamins has been linked to chronic diseases, including coronary heart disease, cancer, and osteoporosis
Abnormal chromosome behavior in Neurospora mutants defective in DNA methylation.
Foss HM, Roberts CJ, Claeys KM, et al.
Science. 1993 Dec 10; 262(5140):1737-41.
The function and regulation of DNA methylation in eukaryotes remain unclear. Genes affecting methylation were identified in the fungus Neurospora crassa. A mutation in one gene, dim-2, resulted in the loss of all detectable DNA methylation. Abnormal segregation of the methylation defects in crosses led to the discovery that the methylation mutants frequently generate strains with extra chromosomes or chromosomal parts. Starvation for S-adenosylmethionine, the presumed methyl group donor for DNA methylation, also produced aneuploidy. These results suggest that DNA methylation plays a role in the normal control of chromosome behavior
Cancer prevention with green tea and monitoring by a new biomarker, hnRNP B1.
Fujiki H, Suganuma M, Okabe S, et al.
Mutat Res. 2001 Sep 1; 480-481:299-304.
The study of green tea polyphenols as a cancer preventative is approaching a new era, with significant results accumulating rapidly. This paper briefly reviews four topics related to mechanisms of action of tea polyphenols: (I) identification of the genes commonly affected by EGCG, as demonstrated by Clontech's Atlas cDNA Expression Array; (II) the significance of heterogeneous nuclear ribonucleoprotein B1 (hnRNP B1) as a new biomarker for early detection of lung cancer, and inhibition of its expression by EGCG; (III) the synergistic or additive effects of EGCG with the cancer preventive agents, sulindac and tamoxifen, on induction of apoptosis in PC-9 cells and on inhibition of intestinal tumor development in multiple intestinal neoplasia (Min) mice; (IV) the results of a 10 year prospective cohort study demonstrating the effectiveness of daily consumption of green tea in preventing cancer, and a prototype study for developing green tea beverage as cancer preventive
Effect of vinpocetine on noradrenergic neurons in rat locus coeruleus.
Gaal L, Molnar P.
Eur J Pharmacol. 1990 Oct 23; 187(3):537-9.
Conventional extracellular single unit recordings were used to investigate the effect of vinpocetine on locus coeruleus noradrenergic neurons in chloral hydrate-anesthetized rats. Vinpocetine produced a significant and dose-dependent increase in the firing rate of locus coeruleus neurons (ED30 = 0.75 mg/kg i.v.) up to 1 mg/kg i.v., followed by a complete blockade of spiking activity at doses higher than this. The effective dose range was in very good agreement with the dose range corresponding to the memory-enhancing effects of the compound. Our results supplied direct electrophysiological evidence that vinpocetine increases the activity of ascending noradrenergic pathways. This effect can be related to the cognitive-enhancing characteristics of the compound
Lower prostate cancer risk in men with elevated plasma lycopene levels: results of a prospective analysis.
Gann PH, Ma J, Giovannucci E, et al.
Cancer Res. 1999 Mar 15; 59(6):1225-30.
Dietary consumption of the carotenoid lycopene (mostly from tomato products) has been associated with a lower risk of prostate cancer. Evidence relating other carotenoids, tocopherols, and retinol to prostate cancer risk has been equivocal. This prospective study was designed to examine the relationship between plasma concentrations of several major antioxidants and risk of prostate cancer. We conducted a nested case-control study using plasma samples obtained in 1982 from healthy men enrolled in the Physicians' Health Study, a randomized, placebo-controlled trial of aspirin and beta-carotene. Subjects included 578 men who developed prostate cancer within 13 years of follow-up and 1294 age- and smoking status-matched controls. We quantified the five major plasma carotenoid peaks (alpha- and beta-carotene, beta-cryptoxanthin, lutein, and lycopene) plus alpha- and gamma-tocopherol and retinol using high-performance liquid chromatography. Results for plasma beta-carotene are reported separately. Odds ratios (ORs), 95% confidence intervals (Cls), and Ps for trend were calculated for each quintile of plasma antioxidant using logistic regression models that allowed for adjustment of potential confounders and estimation of effect modification by assignment to either active beta-carotene or placebo in the trial. Lycopene was the only antioxidant found at significantly lower mean levels in cases than in matched controls (P = 0.04 for all cases). The ORs for all prostate cancers declined slightly with increasing quintile of plasma lycopene (5th quintile OR = 0.75, 95% CI = 0.54-1.06; P, trend = 0.12); there was a stronger inverse association for aggressive prostate cancers (5th quintile OR = 0.56, 95% CI = 0.34-0.91; P, trend = 0.05). In the placebo group, plasma lycopene was very strongly related to lower prostate cancer risk (5th quintile OR = 0.40; P, trend = 0.006 for aggressive cancer), whereas there was no evidence for a trend among those assigned to beta-carotene supplements. However, in the beta-carotene group, prostate cancer risk was reduced in each lycopene quintile relative to men with low lycopene and placebo. The only other notable association was a reduced risk of aggressive cancer with higher alpha-tocopherol levels that was not statistically significant. None of the associations for lycopene were confounded by age, smoking, body mass index, exercise, alcohol, multivitamin use, or plasma total cholesterol level. These results concur with a recent prospective dietary analysis, which identified lycopene as the carotenoid with the clearest inverse relation to the development of prostate cancer. The inverse association was particularly apparent for aggressive cancer and for men not consuming beta-carotene supplements. For men with low lycopene, beta-carotene supplements were associated with risk reductions comparable to those observed with high lycopene. These data provide further evidence that increased consumption of tomato products and other lycopene-containing foods might reduce the occurrence or progression of prostate cancer
Multivitamin use, folate, and colon cancer in women in the Nurses' Health Study.
Giovannucci E, Stampfer MJ, Colditz GA, et al.
Ann Intern Med. 1998 Oct 1; 129(7):517-24.
BACKGROUND: High intake of folate may reduce risk for colon cancer, but the dosage and duration relations and the impact of dietary compared with supplementary sources are not well understood. OBJECTIVE: To evaluate the relation between folate intake and incidence of colon cancer. DESIGN: Prospective cohort study. SETTING: 88,756 women from the Nurses' Health Study who were free of cancer in 1980 and provided updated assessments of diet, including multivitamin supplement use, from 1980 to 1994. PATIENTS: 442 women with new cases of colon cancer. MEASUREMENTS: Multivariate relative risk (RR) and 95% CIs for colon cancer in relation to energy-adjusted folate intake. RESULTS: Higher energy-adjusted folate intake in 1980 was related to a lower risk for colon cancer (RR, 0.69 [95% CI, 0.52 to 0.93] for intake > 400 microg/d compared with intake < or = 200 microg/d) after controlling for age; family history of colorectal cancer; aspirin use; smoking; body mass; physical activity; and intakes of red meat, alcohol, methionine, and fiber. When intake of vitamins A, C, D, and E and intake of calcium were also controlled for, results were similar. Women who used multivitamins containing folic acid had no benefit with respect to colon cancer after 4 years of use (RR, 1.02) and had only nonsignificant risk reductions after 5 to 9 (RR, 0.83) or 10 to 14 years of use (RR, 0.80). After 15 years of use, however, risk was markedly lower (RR, 0.25 [CI, 0.13 to 0.51]), representing 15 instead of 68 new cases of colon cancer per 10,000 women 55 to 69 years of age. Folate from dietary sources alone was related to a modest reduction in risk for colon cancer, and the benefit of long-term multivitamin use was present across all levels of dietary intakes. CONCLUSIONS: Long-term use of multivitamins may substantially reduce risk for colon cancer. This effect may be related to the folic acid contained in multivitamins
Feeding acetyl-L-carnitine and lipoic acid to old rats significantly improves metabolic function while decreasing oxidative stress.
Hagen TM, Liu J, Lykkesfeldt J, et al.
Proc Natl Acad Sci U S A. 2002 Feb 19; 99(4):1870-5.
Mitochondrial-supported bioenergetics decline and oxidative stress increases during aging. To address whether the dietary addition of acetyl-l-carnitine [ALCAR, 1.5% (wt/vol) in the drinking water] and/or (R)-alpha-lipoic acid [LA, 0.5% (wt/wt) in the chow] improved these endpoints, young (2-4 mo) and old (24-28 mo) F344 rats were supplemented for up to 1 mo before death and hepatocyte isolation. ALCAR+LA partially reversed the age-related decline in average mitochondrial membrane potential and significantly increased (P = 0.02) hepatocellular O(2) consumption, indicating that mitochondrial-supported cellular metabolism was markedly improved by this feeding regimen. ALCAR+LA also increased ambulatory activity in both young and old rats; moreover, the improvement was significantly greater (P = 0.03) in old versus young animals and also greater when compared with old rats fed ALCAR or LA alone. To determine whether ALCAR+LA also affected indices of oxidative stress, ascorbic acid and markers of lipid peroxidation (malondialdehyde) were monitored. The hepatocellular ascorbate level markedly declined with age (P = 0.003) but was restored to the level seen in young rats when ALCAR+LA was given. The level of malondialdehyde, which was significantly higher (P = 0.0001) in old versus young rats, also declined after ALCAR+LA supplementation and was not significantly different from that of young unsupplemented rats. Feeding ALCAR in combination with LA increased metabolism and lowered oxidative stress more than either compound alone
Homocysteine levels in patients with stroke: clinical relevance and therapeutic implications.
Hankey GJ, Eikelboom JW.
CNS Drugs. 2001; 15(6):437-43.
High plasma levels of the amino acid homocysteine have been implicated in the development of vascular diseases, including stroke. Elevated plasma levels of total homocysteine (tHcy) above 15 micromol/L are present in less than 5% of the general population, but in as many as 50% of patients with stroke (and other atherothromboembolic vascular diseases). However, it remains uncertain whether a high tHcy level is a causal risk factor for stroke and should be lowered, or is a marker of another factor associated with stroke (e.g. acute tissue damage or tissue repair after an acute vascular event) and therefore should not be lowered. Plasma levels of tHcy can be lowered effectively by folic acid, vitamin B(6) and vitamin B(12) supplementation, and controlled trials have shown some beneficial effects on surrogate markers of vascular function. However, these markers are not established vascular risk factors or valid predictors of 'hard' clinical vascular outcome events. Until it has been shown in large randomised trials [such as the ongoing Vitamins to Prevent Stroke Study (VITATOPS) and the Vitamins in Stroke Prevention (VISP) study] that multivitamin therapy reduces the rate of recurrent stroke and other serious vascular events in patients with prior stroke or transient ischaemic attack, widespread screening for, and treatment of, high tHcy levels remains experimental and cannot be recommended
Pygeum africanum for the treatment of patients with benign prostatic hyperplasia: a systematic review and quantitative meta-analysis.
Ishani A, MacDonald R, Nelson D, et al.
Am J Med. 2000 Dec 1; 109(8):654-64.
PURPOSE: To conduct a systematic review and quantitative meta-analysis of the therapeutic efficacy and tolerability of Pygeum africanum in men with symptomatic benign prostatic hyperplasia. METHODS: Studies were identified through the search of Medline (1966 to 2000), Embase, Phytodok, the Cochrane Library, bibliographies of identified trials and review articles, and contact with relevant authors and drug companies. Randomized trials were included if participants had symptomatic benign prostatic hyperplasia, the intervention was a preparation of P. africanum alone or in combination with other phytotherapeutic agents, a control group received placebo or other pharmacologic therapies for benign prostatic hyperplasia, and treatment duration was at least 30 days. Two investigators independently extracted key data on design features, subject characteristics, and therapy allocation.RESULTS: A total of 18 randomized controlled trials involving 1,562 men met the inclusion criteria and were analyzed. Many studies did not report results in a method that permitted meta-analysis. Only 1 of the studies reported a method of treatment allocation concealment, although 17 were double-blinded. The mean study duration was 64 days (range 30 to 122). Compared with placebo in 6 studies, P. africanum provided a moderately large improvement in the combined outcome of urologic symptoms and flow measures as assessed by an effect size defined by the difference of the mean change for each outcome divided by the pooled standard deviation for each outcome (-0.8 SD [95% confidence interval (CI): -1.4 to -0.3]). Summary estimates of individual outcomes were also improved by P. africanum. Men were more than twice as likely to report an improvement in overall symptoms (risk ratio = 2.1, 95% CI: 1.40 to 3.1). Nocturia was reduced by 19% and residual urine volume by 24%; peak urine flow was increased by 23%. Adverse effects due to P. africanum were mild and similar to placebo. The overall dropout rate was 12% and was similar for P. africanum (13%), placebo (11%), and other controls (8%; P = 0.4 versus placebo and P = 0.5 versus other controls).CONCLUSIONS: The literature on P. africanum for the treatment of benign prostatic hyperplasia is limited by the short duration of studies and the variability in study design, the use of phytotherapeutic preparations, and the types of reported outcomes. However, the evidence suggests that P. africanum modestly, but significantly, improves urologic symptoms and flow measures. Further research is needed using standardized preparations of P. africanum to determine its long-term effectiveness and ability to prevent complications associated with benign prostatic hyperplasia
Effect of citrus flavonoids on HL-60 cell differentiation.
Kawaii S, Tomono Y, Katase E, et al.
Anticancer Res. 1999 Mar; 19(2A):1261-9.
Twenty-seven Citrus flavonoids were examined for their activity of induction of terminal differentiation of human promyelocytic leukemia cells (HL-60) by nitro blue tetrazolium (NBT) reducing, nonspecific esterase, specific esterase, and phagocytic activities. 10 flavonoids were judged to be active (percentage of NBT reducing cells was more than 40% at a concentration of 40 microM), and the rank order of potency was natsudaidain, luteolin, tangeretin, quercetin, apigenin, 3, 3, '4, '5, 6, 7, 8-heptamethoxyflavone, nobiletin, acacetin, eriodictyol, and taxifolin. These flavonoids exerted their activity in a dose-dependent manner. HL-60 cells treated with these flavonoids differentiated into mature monocyte/macrophage. The structure-activity relationship established from comparison between flavones and flavanones revealed that ortho-catechol moiety in ring B and C2-C3 double bond had an important role for induction of differentiation of HL-60. In polymethoxylated flavones, hydroxyl group at C3 and methoxyl group at C8 enhanced the differentiation-inducing activity
Relation between plasma ascorbic acid and mortality in men and women in EPIC-Norfolk prospective study: a prospective population study. European Prospective Investigation into Cancer and Nutrition.
Khaw KT, Bingham S, Welch A, et al.
Lancet. 2001 Mar 3; 357(9257):657-63.
BACKGROUND: Ascorbic acid (vitamin C) might be protective for several chronic diseases. However, findings from prospective studies that relate ascorbic acid to cardiovascular disease or cancer are not consistent. We aimed to assess the relation between plasma ascorbic acid and subsequent mortality due to all causes, cardiovascular disease, ischaemic heart disease, and cancer. METHODS: We prospectively examined for 4 years the relation between plasma ascorbic acid concentrations and mortality due to all causes, and to cardiovascular disease, ischaemic heart disease, and cancer in 19 496 men and women aged 45-79 years. We recruited individuals by post using age-sex registers of general practices. Participants completed a health and lifestyle questionnaire and were examined at a clinic visit. They were followed-up for causes of death for about 4 years. Individuals were divided into sex-specific quintiles of plasma ascorbic acid. We used the Cox proportional hazard model to determine the effect of ascorbic acid and other risk factors on mortality. FINDINGS: Plasma ascorbic acid concentration was inversely related to mortality from all-causes, and from cardiovascular disease, and ischaemic heart disease in men and women. Risk of mortality in the top ascorbic acid quintile was about half the risk in the lowest quintile (p<0.0001). The relation with mortality was continuous through the whole distribution of ascorbic acid concentrations. 20 micromol/L rise in plasma ascorbic acid concentration, equivalent to about 50 g per day increase in fruit and vegetable intake, was associated with about a 20% reduction in risk of all-cause mortality (p<0.0001), independent of age, systolic blood pressure, blood cholesterol, cigarette smoking habit, diabetes, and supplement use. Ascorbic acid was inversely related to cancer mortality in men but not women. INTERPRETATION: Small increases in fruit and vegetable intake of about one serving daily has encouraging prospects for possible prevention of disease
S-nitrosation ameliorates homocysteine-induced neurotoxicity and calcium responses in primary culture of rat cortical neurons.
Neurosci Lett. 1999 Apr 16; 265(2):99-102.
Homocyteine (HC) induces neurotoxicity through overstimulation of N-methyl-D-aspartate (NMDA) receptors in cortical neurons. Due to its high reactivity, the sulfhydryl group of HC may react with nitric oxide (NO). In the present study S-nitrosation decreased the homocysteine-evoked LDH releases from rat cortical neuronal cultures. Like HC, S-nitrosohomocysteine increased the intracellular calcium concentration ([Ca2+]i) via NMDA receptor. However, S-nitrosohomocysteine was much less efficacious than HC for the increase of [Ca2+]i. Elevation of the glycine concentration to 50 microM significantly increased the maximal calcium response of S-nitrosohomocyteine, but not high enough to match that of HC in the presence of the same concentration of glycine. S-nitrosohomocysteine partially decreased the NMDA calcium responses in the presence of 1 and 50 microM glycine, at least in part via the redox-modulatory site(s) of the NMDA receptor. These data indicate that NO ameliorates the potential, adverse properties of HC via S-nitrosylation in the pathogenesis of hyperhomocysteinemia
Folate deficiency in rats induces DNA strand breaks and hypomethylation within the p53 tumor suppressor gene.
Kim YI, Pogribny IP, Basnakian AG, et al.
Am J Clin Nutr. 1997 Jan; 65(1):46-52.
Folate is essential for the de novo biosynthesis of purines and thymidylate, and is an important mediator in the transfer of methyl groups for DNA methylation. Folate deficiency, therefore, could contribute to abnormal DNA integrity and methylation patterns. We investigated the effect of isolated folate deficiency in rats on DNA methylation and DNA strand breaks both at the genomic level and within specific sequences of the p53 tumor suppressor gene. Our data indicate that folate deficiency induces DNA strand breaks and hypomethylation within the p53 gene. Such alterations either did not occur or were chronologically delayed when examined on a genome-wide basis, indicating some selectivity for the exons examined within the p53 gene. Folate insufficiency has been implicated in the development of several human and experimental cancers, and aberrations within these regions of the p53 gene that were examined in this study are thought to play an integral role in carcinogenesis. The aforementioned molecular alterations may therefore be a means by which dietary folate deficiency enhances carcinogenesis
[Mechanism of action of vinpocetine].
Kiss B, Karpati E.
Acta Pharm Hung. 1996 Sep; 66(5):213-24.
Cavinton was introduced into the clinical practice some twenty years ago in Hungary for the treatment of cerebrovascular disorders and related symptoms. Since then, its active ingredient, vinpocetine, beside its therapeutical utilization, has become a reference compound in the pharmacological research of cognitive deficits caused by hypoxia and ischaemia as well as in the cellular and biochemical investigations related to cyclic nucleotides. In this review a survey is given on the experimental data obtained with vinpocetine and an attempt is made to outline the drug's mechanism of action. Early experiments with vinpocetine indicated five main pharmacological and biochemical actions: (1) selective enhancement of the brain circulation and oxygen utilization without significant alteration in parameters of systemic circulation, (2) increased tolerance of the brain toward hypoxia and ischemia, (3) anticonvulsant activity, (4) inhibitory effect on phosphodiesterase (PDE) enzyme and (5) improvement of rheological properties of the blood and inhibition of aggregation of thrombocytes. Later studies in various laboratories confirmed the above effects and clearly demonstrated that vinpocetine offers significant and direct neuroprotection both under in vitro and in vivo conditions. Evidence has been obtained that neuroprotective action vinpocetine is related to the inhibition of operation of voltage dependent neuronal Na(+)-channels, indirect inhibition of some molecular cascades initiated by the rise of intracellular Ca(2+)-levels and, to a lesser extent, inhibition of adenosine reuptake. Vinpocetine has been shown to be selective inhibitor of Ca(2+)-calmodulin dependent cGMP-PDE. It is assumed that this inhibition enhances intracellular a GMP levels in the vascular smooth muscle leading to reduced resistance of cerebral vessels and increase of cerebral flow. This effect might also beneficially contribute to the neuroprotective action
Antiproliferative effect on human prostate cancer cells by a stinging nettle root (Urtica dioica) extract.
Konrad L, Muller HH, Lenz C, et al.
Planta Med. 2000 Feb; 66(1):44-7.
In the present study the activity of a 20% methanolic extract of stinging nettle roots (Urtica dioica L., Urticaceae) on the proliferative activity of human prostatic epithelial (LNCaP) and stromal (hPCPs) cells was evaluated using a colorimetric assay. A concentration-dependent and significant (p < 0.05) antiproliferative effect of the extract was observed only on LNCaP cells during 7 days, whereas stromal cell growth remained unaltered. The inhibition was time-dependent with the maximum of growth reduction (30%) at a concentration of 1.0E-6 mg/ml on day 5 compared to the untreated control. On day 4 and 6, the reduction in proliferation of LNCaP cells showed the minimal effective dose at 1.0E-9 mg/ml. No cytotoxic effect of ME-20 on cell proliferation was observed. The antiproliferative effect of ME-20 of stinging nettle roots observed both in an in vivo model and in an in vitro system clearly indicates a biologically relevant effect of compounds present in the extract
The antiatherosclerotic effect of Allium sativum.
Koscielny J, Klussendorf D, Latza R, et al.
Atherosclerosis. 1999 May; 144(1):237-49.
In a randomized, double-blind, placebo-controlled clinical trial, the plaque volumes in both carotid and femoral arteries of 152 probationers were determined by B-mode ultrasound. Continuous intake of high-dose garlic powder dragees reduced significantly the increase in arteriosclerotic plaque volume by 5-18% or even effected a slight regression within the observational period of 48 months. Also the age-dependent representation of the plaque volume shows an increase between 50 and 80 years that is diminished under garlic treatment by 6-13% related to 4 years. It seems even more important that with garlic application the plaque volume in the whole collective remained practically constant within the age-span of 50-80 years. These results substantiated that not only a preventive but possibly also a curative role in arteriosclerosis therapy (plaque regression) may be ascribed to garlic remedies
Inhibitory effects of ellagic acid on the direct-acting mutagenicity of aflatoxin B1 in the Salmonella microsuspension assay.
Loarca-Pina G, Kuzmicky PA, de Mejia EG, et al.
Mutat Res. 1998 Feb 26; 398(1-2):183-7.
Ellagic acid (EA) is a phenolic compound that exhibits both antimutagenic and anticarcinogenic activity in a wide range of assays in vitro and in vivo. It occurs naturally in some foods such as strawberries, raspberries, and grapes. In the previous work, we used the Salmonella microsuspension assay to examine the antimutagenicity of EA against the potent mutagen aflatoxin B1 (AFB1) using tester strains TA98 and TA100. Briefly, the microsuspension assay was approximately 10 times more sensitive than the standard Salmonella/microsome (Ames) test in detecting AFB1 mutagenicity, and EA significantly inhibited mutagenicity of all AFB1 doses in both tester strains with the addition of S9. The greatest inhibitory effect of EA on AFB1 mutagenicity occurred when EA and AFB1 were incubated together (with metabolic enzymes). Lower inhibition was apparent when the cells were first incubated with EA followed by a second incubation with AFB1, or when the cells were first incubated with AFB1 followed by a second incubation with EA alone, all with metabolic enzymes. The result of these sequential incubation studies indicates that one mechanism of inhibition could involve the formation of an AFB1-EA chemical complex. In the present study, we further examine the effect of EA on AFB1 mutagenicity, but without the addition of exogenous metabolic enzymes. We report the mutagenicity of AFB1 in the microsuspension assay using TA98 and TA100 without the addition of S9. Neither the concentrations of AFB1 (0.6, 1.2, and 2.4 microg/tube) nor the concentrations of EA (0.3, 1.5, 3, 10, and 20 microg/tube) were toxic to the bacteria. The results indicate that AFB1 is a direct-acting mutagen, and that EA inhibits AFB1 direct-acting mutagenicity
Vitamin E and vitamin C supplement use and risk of all-cause and coronary heart disease mortality in older persons: the Established Populations for Epidemiologic Studies of the Elderly.
Losonczy KG, Harris TB, Havlik RJ.
Am J Clin Nutr. 1996 Aug; 64(2):190-6.
We examined vitamin E and vitamin C supplement use in relation to mortality risk and whether vitamin C enhanced the effects of vitamin E in 11,178 persons aged 67-105 y who participated in the Established Populations for Epidemiologic Studies of the Elderly in 1984-1993. Participants were asked to report all nonprescription drugs currently used, including vitamin supplements. Persons were defined as users of these supplements if they reported individual vitamin E and/or vitamin C use, not part of a multivitamin. During the follow-up period there were 3490 deaths. Use of vitamin E reduced the risk of all-cause mortality [relative risk (RR) = 0.66; 95% CI: 0.53, 0.83] and risk of coronary disease mortality (RR = 0.53; 95% CI: 0.34, 0.84). Use of vitamin E at two points in time was also associated with reduced risk of total mortality compared with that in persons who did not use any vitamin supplements. Effects were strongest for coronary heart disease mortality (RR = 0.37; 95% CI: 0.15, 0.90). The RR for cancer mortality was 0.41 (95% CI: 0.15, 1.08). Simultaneous use of vitamins E and C was associated with a lower risk of total mortality (RR = 0.58; 95% CI: 0.42, 0.79) and coronary mortality (RR = 0.47; 95% CI: 0.25, 0.87). Adjustment for alcohol use, smoking history, aspirin use, and medical conditions did not substantially alter these findings. These findings are consistent with those for younger persons and suggest protective effects of vitamin E supplements in the elderly
Plasma homocyst(e)ine levels and graded risk for myocardial infarction: findings in two populations at contrasting risk for coronary heart disease.
Malinow MR, Ducimetiere P, Luc G, et al.
Atherosclerosis. 1996 Sep 27; 126(1):27-34.
Standardized mortality rates for coronary heart disease (CHD) in men are about 3-fold higher in Northern Ireland than in France. The differences could not be explained by the presence of conventional risk factors for atherosclerosis. We studied in subjects from these two countries, an additional risk factor, namely, concentration of plasma homocyst(e)ine which is frequently elevated in patients with CHD. We measured the plasma concentration of homocyst(e)ine in survivors of myocardial infarction (MI) and in control subjects from the Belfast, Strasbourg and Lille regions. Plasma homocyst(e)ine levels were higher in the Irish than in the French controls; subjects with MI had higher levels than controls. Results were compatible with global excess of risk for MI being graded across the distribution of plasma homocyst(e)ine concentrations, although the trends lost significance in Belfast after adjustment for other risk factors. The higher plasma homocyst(e)ine concentrations we observed in the Irish population could be the reason for the different CHD mortality rates. This epidemiological observation could prompt dietary and vitamin supplementation studies aimed at decreasing homocyst(e)ine levels as well as the incidence of arterial occlusive disease, under controlled conditions in high risk populations
Reduction of plasma homocyst(e)ine levels by breakfast cereal fortified with folic acid in patients with coronary heart disease.
Malinow MR, Duell PB, Hess DL, et al.
N Engl J Med. 1998 Apr 9; 338(15):1009-15.
BACKGROUND: The Food and Drug Administration (FDA) has recommended that cereal-grain products be fortified with folic acid to prevent congenital neural-tube defects. Since folic acid supplementation reduces levels of plasma homocyst(e)ine, or plasma total homocysteine, which are frequently elevated in arterial occlusive disease, we hypothesized that folic acid fortification might reduce plasma homocyst(e)ine levels. METHODS: To test this hypothesis, we assessed the effects of breakfast cereals fortified with three levels of folic acid, and also containing the recommended dietary allowances of vitamins B6 and B12, in a randomized, double-blind, placebo-controlled, crossover trial in 75 men and women with coronary artery disease. RESULTS: Plasma folic acid increased and plasma homocyst(e)ine decreased proportionately with the folic acid content of the breakfast cereal. Cereal providing 127 microg of folic acid daily, approximating the increased daily intake that may result from the FDA's enrichment policy, increased plasma folic acid by 31 percent (P=0.045) but decreased plasma homocyst(e)ine by only 3.7 percent (P= 0.24). However, cereals providing 499 and 665 microg of folic acid daily increased plasma folic acid by 64.8 percent (P<0.001) and 105.7 percent (P=0.001), respectively, and decreased plasma homocyst(e)ine by 11.0 percent (P<0.001) and 14.0 percent (P=0.001), respectively. CONCLUSIONS: Cereal fortified with folic acid has the potential to increase plasma folic acid levels and reduce plasma homocyst(e)ine levels. Further clinical trials are required to determine whether folic acid fortification may prevent vascular disease. Until then, our results suggest that folic acid fortification at levels higher than that recommended by the FDA may be warranted
Effects of a saw palmetto herbal blend in men with symptomatic benign prostatic hyperplasia.
Marks LS, Partin AW, Epstein JI, et al.
J Urol. 2000 May; 163(5):1451-6.
PURPOSE: We tested the effects of a saw palmetto herbal blend in men with symptomatic benign prostatic hyperplasia (BPH) via a randomized, placebo controlled trial. MATERIALS AND METHODS: We randomized 44 men 45 to 80 years old with symptomatic BPH into a trial of a saw palmetto herbal blend versus placebo. End points included routine clinical measures (symptom score, uroflowmetry and post-void residual urine volume), blood chemistry studies (prostate specific antigen, sex hormones and multiphasic analysis), prostate volumetrics by magnetic resonance imaging, and prostate biopsy for zonal tissue morphometry and semiquantitative histology studies. RESULTS: Saw palmetto herbal blend and placebo groups had improved clinical parameters with a slight advantage in the saw palmetto group (not statistically significant). Neither prostate specific antigen nor prostate volume changed from baseline. Prostate epithelial contraction was noted, especially in the transition zone, where percent epithelium decreased from 17.8% at baseline to 10.7% after 6 months of saw palmetto herbal blend (p <0.01). Histological studies showed that the percent of atrophic glands increased from 25. 2% to 40.9% after treatment with saw palmetto herbal blend (p <0.01). The mechanism of action appeared to be nonhormonal but it was not identified by tissue studies of apoptosis, cellular proliferation, angiogenesis, growth factors or androgen receptor expression. We noted no adverse effects of saw palmetto herbal blend. When the study was no longer blinded, 41 men elected to continue therapy in an open label extension. CONCLUSIONS: Saw palmetto herbal blend appears to be a safe, highly desirable option for men with moderately symptomatic BPH. The secondary outcome measures of clinical effect in our study were only slightly better for saw palmetto herbal blend than placebo (not statistically significant). However, saw palmetto herbal blend therapy was associated with epithelial contraction, especially in the transition zone (p <0.01), indicating a possible mechanism of action underlying the clinical significance detected in other studies
Importance of elevated plasma homocysteine levels as a risk factor for atherosclerosis.
Masser PA, Taylor LM, Jr., Porter JM.
Ann Thorac Surg. 1994 Oct; 58(4):1240-6.
Atherosclerosis is a leading cause of death and disability in the Western world, and an important risk factor for it may be an elevated level of the plasma amino acid homocysteine. The biochemical characteristics of homocysteine, along with historical, laboratory, and clinical evidence for its pathologic role in atherosclerosis, are reviewed. Possible therapies for reducing elevated homocysteine levels and the possible impact of therapy in atherosclerosis are examined
Elevated plasma homocysteine levels and risk of silent brain infarction in elderly people.
Matsui T, Arai H, Yuzuriha T, et al.
Stroke. 2001 May; 32(5):1116-9.
BACKGROUND AND PURPOSE: Silent brain infarction (SBI) on MRI is common in elderly people, and recent studies have demonstrated that SBI increases the risk of progression to clinically apparent stroke and cognitive decline. Therefore, an early and accurate detection of SBI and a search for potential treatable risk factors may have a significant impact on public health. METHODS: Community-dwelling elderly people aged >/=66 years who participated in the present study (n=153) underwent brain MRI and standardized physical and neuropsychological examinations as well as blood biochemistry determinations, including total plasma homocysteine (pHcy), renal function, vitamin status, and polymorphisms of the methylenetetrahydrofolate reductase gene. RESULTS: SBI was found in 24.8% of the participants. In the univariate analysis, the pHcy levels in subjects with SBI (13.6+/-4.1 micromol/L) were significantly higher (P=0.0004) than those in subjects without SBI (11.0+/-3.3 micromol/L). When pHcy levels were stratified into high (>/=15.1 mmol/L), moderate (11.6 to 15.0 mmol/L), and low (
Influence of advanced glycation end-products and AGE-inhibitors on nucleation-dependent polymerization of beta-amyloid peptide.
Munch G, Mayer S, Michaelis J, et al.
Biochim Biophys Acta. 1997 Feb 27; 1360(1):17-29.
Nucleation-dependent polymerization of beta-amyloid peptide, the major component of plaques in patients with Alzheimer's disease, is significantly accelerated by crosslinking through Advanced Glycation End-products (AGEs) in vitro. During the polymerization process, both nucleus formation and aggregate growth are accelerated by AGE-mediated crosslinking. Formation of the AGE-crosslinked amyloid peptide aggregates could be attenuated by the AGE-inhibitors Tenilsetam, aminoguanidine and carnosine. These experimental data, and clinical studies, reporting a marked improvement in cognition and memory in Alzheimer's disease patients after Tenilsetam treatment, suggest that AGEs might play an important role in the etiology or progression of the disease. Thus AGE-inhibitors may generally become a promising drug class for the treatment of Alzheimer's disease
Studies on the relationship between boron and magnesium which possibly affects the formation and maintenance of bones.
Magnes Trace Elem. 1990; 9(2):61-9.
Recent findings are reviewed indicating that changes in dietary boron and magnesium affect calcium, and thus bone, metabolism in animals and humans. In animals, the need for boron was found to be enhanced when they needed to respond to a nutritional stress which adversely affected calcium metabolism, including magnesium deficiency. A combined deficiency of boron and magnesium caused detrimental changes in the bones of animals. However, boron deprivation did not seem to enhance the requirement for magnesium. In two human studies, boron deprivation caused changes in variables associated with calcium metabolism in a manner that could be construed as being detrimental to bone formation and maintenance; these changes apparently were enhanced by low dietary magnesium. Changes caused by boron deprivation included depressed plasma ionized calcium and calcitonin as well as elevated plasma total calcium and urinary excretion of calcium. In one human study, magnesium deprivation depressed plasma ionized calcium and cholesterol. Because boron and/or magnesium deprivation causes changes similar to those seen in women with postmenopausal osteoporosis, these elements are apparently needed for optimal calcium metabolism and are thus needed to prevent the excessive bone loss which often occurs in postmenopausal women and older men
Effects of flavonoids and vitamin C on oxidative DNA damage to human lymphocytes.
Noroozi M, Angerson WJ, Lean ME.
Am J Clin Nutr. 1998 Jun; 67(6):1210-8.
This study assessed the antioxidant potencies of several widespread dietary flavonoids across a range of concentrations and compared with vitamin C as a positive control. The antioxidant effects of pretreatment with flavonoids and vitamin C, at standardized concentrations (7.6, 23.2, 93, and 279.4 micromol/L), on oxygen radical-generated DNA damage from hydrogen peroxide (100 micromol/L) in human lymphocytes were examined by using the single-cell gel electrophoresis assay (comet assay). Pretreatment with all flavonoids and vitamin C produced dose-dependent reductions in oxidative DNA damage. At a concentration of 279 micromol/L, they were ranked in decreasing order of potency as follows: luteolin (9% of damage from unopposed hydrogen peroxide), myricetin (10%), quercetin (22%), kaempferol (32%), quercitrin (quercetin-3-L-rhamnoside) (45%), apigenin (59%), quercetin-3-glucoside (62%), rutin (quercetin-3-beta-D-rutinoside) (82%), and vitamin C (78%). The protective effect of vitamin C against DNA damage at this concentration was significantly less than that of all the flavonoids except apigenin, quercetin-3-glucoside, and rutin. The ranking was similar with estimated ED50 (concentration to produce 50% protection) values. The protective effect of quercetin and vitamin C at a concentration of 23.2 micromol/L was found to be additive (quercetin: 71% of maximal DNA damage from unopposed hydrogen peroxide; vitamin C: 83%; both in combination: 62%). These data suggest that the free flavonoids are more protective than the conjugated flavonoids (eg, quercetin compared with its conjugate quercetin-3-glucoside, P < 0.001). Data are also consistent with the hypothesis that antioxidant activity of free flavonoids is related to the number and position of hydroxyl groups
Vitamin C deficiency and risk of myocardial infarction: prospective population study of men from eastern Finland.
Nyyssonen K, Parviainen MT, Salonen R, et al.
BMJ. 1997 Mar 1; 314(7081):634-8.
OBJECTIVE: To examine the association between plasma vitamin C concentrations and the risk of acute myocardial infarction. DESIGN: Prospective population study. SETTING: Eastern Finland. SUBJECTS: 1605 randomly selected men aged 42, 48, 54, or 60 who did not have either symptomatic coronary heart disease or ischaemia on exercise testing at entry to the Kuopio ischaemic heart disease risk factor study in between 1984 and 1989. MAIN OUTCOME MEASURES: Number of acute myocardial infarctions; fasting plasma vitamin C concentrations at baseline. RESULTS: 70 of the men had a fatal or non-fatal myocardial infarction between March 1984 and December 1992.91 men had vitamin C deficiency (plasma ascorbate < 11.4 mumol/l, or 2.0 mg/l), of whom 12 (13.2%) had a myocardial infarction; 1514 men were not deficient in vitamin C, of whom 58 (3.8%) had a myocardial infarction. In a Cox proportional hazards model adjusted for age, year of examination, and season of the year examined (August to October v rest of the year) men who had vitamin C deficiency had a relative risk of acute myocardial infarction of 3.5 (95% confidence interval 1.8 to 6.7, P = 0.0002) compared with those who were not deficient. In another model adjusted additionally for the strongest risk factors for myocardial infarction and for dietary intakes of tea fibre, carotene, and saturated fats men with a plasma ascorbate concentration < 11.4 mumol/l had a relative risk of 2.5 (1.3 to 5.2, P = 0.0095) compared with men with higher plasma vitamin C concentrations. CONCLUSIONS: Vitamin C deficiency, as assessed by low plasma ascorbate concentration, is a risk factor for coronary heart disease
Eat right and take a multivitamin.
Oakley GP, Jr.
N Engl J Med. 1998 Apr 9; 338(15):1060-1.
Dietary glucarate-mediated inhibition of initiation of diethylnitrosamine-induced hepatocarcinogenesis.
Oredipe OA, Barth RF, Dwivedi C, et al.
Toxicology. 1992 Sep; 74(2-3):209-22.
Previously, it has been reported that calcium glucarate is a potent inhibitor of chemical carcinogenesis, including phenobarbital-promoted diethylnitrosamine-initiated hepatic toxicity expressed as altered hepatic foci in rats. The purpose of the present study was to determine whether calcium glucarate could inhibit the immediate and delayed appearance of altered hepatic foci when fed to rats during the initiation phase of diethylnitrosamine-induced hepatocarcinogenesis. The effects of dietary mode of administration of calcium glucarate on the initiation phase of hepatocarcinogenesis were also examined. Since diethylnitrosamine is not known to undergo glucuronidation and calcium glucarate has been shown to enhance clearance of circulating estrogens, an indirect mechanism of action of calcium glucarate was also evaluated by pretreating rats with an anti-estrogen, tamoxifen, prior to partial hepatectomy and administration of diethylnitrosamine. Calcium glucarate significantly inhibited both the early and delayed appearance of altered hepatic foci and exerted maximal inhibition when administered by gavage prior to diethylnitrosamine. Maximal inhibition was obtained when calcium glucarate was provided continuously in the diet of animals up to 5 and 7 months. Pretreatment of animals with tamoxifen before partial hepatectomy and diethylnitrosamine resulted in maximal inhibition of the initiation phase of hepatocarcinogenesis. This suggests but does not prove that the anti-carcinogenic activity of calcium glucarate was due to decreased liver proliferation. In the present study, the proliferation of ductular epithelial and oval cells appeared to be associated with the administration of diethylnitrosamine. Collectively, our data suggest that calcium glucarate inhibited the initiation phase of diethylnitrosamine-induced hepatocarcinogenesis
Tea catechins inhibit cholesterol oxidation accompanying oxidation of low density lipoprotein in vitro.
Osada K, Takahashi M, Hoshina S, et al.
Comp Biochem Physiol C Toxicol Pharmacol. 2001 Feb; 128(2):153-64.
Endogenous oxidized cholesterols are potent atherogenic agents. Therefore, the antioxidative effects of green tea catechins (GTC) against cholesterol oxidation were examined in an in vitro lipoprotein oxidation system. The antioxidative potency of GTC against copper catalyzed LDL oxidation was in the decreasing order (-)-epigalocatechin gallate (EGCG)=(-)-epicatechin gallate (ECG)>(-)-epicatechin (EC)=(+)-catechin (C)>(-)-epigallocatechin (EGC). Reflecting these activities, both EGCG (74%) and ECG (70%) inhibited the formation of oxidized cholesterol, as well as the decrease of linoleic and arachidonic acids, in copper catalyzed LDL oxidation. The formation of oxidized cholesterol in 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH)-mediated oxidation of rat plasma was also inhibited when the rats were given diets containing 0.5% ECG or EGCG. In addition, EGCG and ECG highly inhibited oxygen consumption and formation of conjugated dienes in AAPH-mediated linoleic acid peroxidative reaction. These two species of catechin also markedly lowered the generation of hydroxyl radical and superoxide anion. Thus, GTC, especially ECG and EGCG, seem to inhibit cholesterol oxidation in LDL by combination of interference with PUFA oxidation, the reduction and scavenging of copper ion, hydroxyl radical generated from peroxidation of PUFA and superoxide anion
Effect of coenzyme Q10 (CoQ10) on superoxide dismutase activity in ET-1 and ET-3 experimental models of cerebral ischemia in the rat.
Folia Neuropathol. 1999; 37(4):247-51.
The aim of the work was to evaluate the influence of CoQ10 on superoxide dismutase (SOD) activity levels in the rat model of cerebral ischemia induced by endothelins (ET-1 or ET-3). ETs (20 pmol) were injected into the right lateral cerebral ventricle and immediately CoQ10 was given intraperitoneally (10 mg/kg b.w.). In the brains of experimental animals subjected both to ET-1 and ET-2 administration there was observed a decrease of SOD activity in the brain stem, in the cerebrallum and in the cerebral cortex at all time intervals. ET-1, as compared to ET-3 evoked longer lasting disturbances in SOD activity. In the cerebellum and in the cerebral cortex positive effect of CoQ10 and recovery to the control values was noted after 4 hours in the group subjected to ET-3 injection and after 24 hours in the ET-1 treated animal. Investigated brain areas showed different sensitivity to ETs. Above data may indicate on beneficial effect CoQ10 in the cerebral ischemia via decrease of free radicals concentration
Effect of coenzyme Q(10) on biochemical and morphological changes in experimental ischemia in the rat brain.
Brain Res Bull. 2000 Nov 1; 53(4):399-407.
The aim of the work was to evaluate an influence of CoQ(10) on lactate acidosis, adenosine-5'-triphosphate (ATP) concentrations, oxidized to reduced glutathione ratio and on superoxide dismutase activity in endothelin model of cerebral ischemia in the rat. Light microscopic studies in the central nervous system and morphometric analysis of pyramidal cells in the hippocampus were also performed. Endothelins (ET-1 or ET-3; 20 pmoles) were injected into the right lateral cerebral ventricle (intracerebroventricularly). CoQ(10) was given intraperitoneally (i.p.) just before the operation (i.p. 10 mgkg b. wt.). More severe changes of investigated biochemical parameters were observed in the animals treated with ET-1 in comparison with ET-3. Recovery was noted earlier in the group subjected to ET-3 and CoQ(10) administration, than in the animals subjected to ET-1 and CoQ(10) treatment. Histopathological observations showed sparse foci of a neuronal loss in the cerebral cortex and in the hippocampus only in the ET-1 model of ischemia. Additionally more numerous dark neurons were present in above brain structures following ET-1 administration comparing with ET-3 one. Morphometrical studies demonstrated that CoQ(10) diminished neuronal injury in the hippocampal CA1, CA2 and CA3 zones. Above data indicate on neuroprotective effect of CoQ(10) as a potent antioxidant and oxygen derived free radicals scavenger in the cerebral ischemia
Toxic effects of beta-amyloid(25-35) on immortalised rat brain endothelial cell: protection by carnosine, homocarnosine and beta-alanine.
Preston JE, Hipkiss AR, Himsworth DT, et al.
Neurosci Lett. 1998 Feb 13; 242(2):105-8.
The effect of a truncated form of the neurotoxin beta-amyloid peptide (A beta25-35) on rat brain vascular endothelial cells (RBE4 cells) was studied in cell culture. Toxic effects of the peptide were seen at 200 microg/ml A beta using a mitochondrial dehydrogenase activity (MTT) reduction assay, lactate dehydrogenase release and glucose consumption. Cell damage could be prevented completely at 200 microg/ml A beta and partially at 300 microg/ml A beta, by the dipeptide carnosine. Carnosine is a naturally occurring dipeptide found at high levels in brain tissue and innervated muscle of mammals including humans. Agents which share properties similar to carnosine, such as beta-alanine, homocarnosine, the anti-glycating agent aminoguanidine, and the antioxidant superoxide dismutase (SOD), also partially rescued cells, although not as effectively as carnosine. We postulate that the mechanism of carnosine protection lies in its anti-glycating and antioxidant activities, both of which are implicated in neuronal and endothelial cell damage during Alzheimer's disease. Carnosine may therefore be a useful therapeutic agent
Interleukin 6 production by lipopolysaccharide-stimulated human fibroblasts is potently inhibited by naphthoquinone (vitamin K) compounds.
Reddi K, Henderson B, Meghji S, et al.
Cytokine. 1995 Apr; 7(3):287-90.
Naphthoquinone vitamins (vitamins K) are widely recognized for their role in the gamma-carboxylation of specific glutamyl residues in coagulation, anti-coagulation and extra-hepatic proteins. Recently, however, there have been reports that these compounds can exert actions other than those normally associated with protein gamma-carboxylation. These observations suggest that naphthoquinones may have effects on the production of inflammatory mediators including cytokines. Fibroblasts are now recognized as a rich source of cytokines and we have examined the effect of various naphthoquinones on the production of interleukin 6 (IL-6) by lipopolysaccharide-stimulated human gingival fibroblasts. Compounds examined in this study include: phylloquinone (K1), menaquinone-4 (K2), menadione (K3), 2,3-dimethoxy-1,4-naphthoquinone (DMK) and a synthetic product of vitamin K catabolism, 2-methyl, 3-(2'methyl)-hexanoic acid-1,4-naphthoquinone (KCAT). All of these compounds are capable of inhibiting IL-6 production with a rank order of potency: KCAT > K3 > DMK > K2 > K1. The most potent compound, KCAT, inhibited IL-6 production with an IC50 of 3 x 10(-7)M. The mechanism of action of these naphthoquinones on fibroblast IL-6 production is unknown. Given that K3 and KCAT are inactive in the gamma-carboxylation reaction, we suggest that this activity is not essential for the inhibition of IL-6 production and that activity may be related to the redox capacity of these naphthoquinones
Prevention of restenosis after angioplasty in small coronary arteries with probucol.
Rodes J, Cote G, Lesperance J, et al.
Circulation. 1998 Feb 10; 97(5):429-36.
BACKGROUND: Restenosis remains the major limitation of coronary angioplasty. Coronary stents have reduced the incidence of restenosis in selected patients with relatively large vessels. No strategies to date have demonstrated a beneficial effect in vessels < 3.0 mm in diameter. We have shown in the MultiVitamins and Probucol (MVP) Trial that probucol, a potent antioxidant, reduces restenosis after balloon angioplasty. The purpose of this study was to determine whether the benefit of probucol therapy is maintained in the subgroup of patients with smaller coronary vessels. METHODS AND RESULTS: We studied a subgroup of 189 patients included in the MVP trial who underwent successful balloon angioplasty of at least one coronary segment with a reference diameter < 3.0 mm. One month before angioplasty, patients were randomly assigned to one of four treatments: placebo, probucol (500 mg), multivitamins (beta-carotene 30000 IU, vitamin C 500 mg, and vitamin E 700 IU), or probucol plus multivitamins twice daily. The treatment was maintained until follow-up angiography was performed at 6 months. The mean reference diameter of this study population was 2.49+/-0.34 mm. Lumen loss was 0.12+/-0.34 mm for probucol, 0.25+/-0.43 mm for the combined treatment, 0.35+/-0.56 mm for vitamins, and 0.38+/-0.51 mm for placebo (P=.005 for probucol). Restenosis rates per segment were 20.0% for probucol, 28.6% for the combined treatment, 45.1% for vitamins, and 37.3% for placebo (P=.006 for probucol). CONCLUSIONS: Probucol reduces lumen loss and restenosis rate after balloon angioplasty in small coronary arteries
Association between low plasma vitamin E concentration and progression of early cortical lens opacities.
Rouhiainen P, Rouhiainen H, Salonen JT.
Am J Epidemiol. 1996 Sep 1; 144(5):496-500.
The authors evaluated the association between plasma vitamin E content and progression of eye lens opacities. A total of 410 hypercholesterolemic eastern Finnish men participated in the study from January 1990 to September 1993 in Kuopio, Finland. Lens opacities were classified three times at 18-month intervals using the Lens Opacities Classification System II. A low plasma vitamin E level (lowest quartile) was associated with a 3.7-fold excess risk (95% confidence interval 1.2-11.8) of the progression of early cortical lens opacities compared with the highest quartile (p = 0.028). In addition, the number of cigarettes smoked daily was a significant predictor of the progression of cortical lens opacity (relative risk = 1.06 per cigarette, 95% confidence interval 1.003-1.12). The progression of nuclear lens opacities was not associated with either the plasma vitamin E content or smoking. The data suggest that low plasma vitamin E content may be associated with increased risk of the progression of early cortical lens opacity
Newer risk factors for stroke.
Neurology. 2001; 57(5 Suppl 2):S31-S34.
Stroke places a tremendous burden on health resources throughout the world. Improved detection and modification of risk factors could reduce the impact of this disease. Important non-modifiable risk factors for ischemic stroke include age, gender, ethnicity, and heredity. Modifiable risk factors include hypertension, cardiovascular disease, diabetes, hyperlipidemia, asymptomatic carotid stenosis, cigarette smoking, and alcohol abuse. Data from the Northern Manhattan Stroke Study provide new insights into these stroke risk factors. In this study, African-Americans and Hispanics had a greater incidence of stroke, with almost a twofold increase compared with Caucasians. The protective effect of physical activity and moderate alcohol consumption was confirmed and further established as modifiable risk factors. The independent effects of lipids, apolipoproteins, and lipoprotein were also clarified. High-density lipoprotein was shown to be protective against ischemic stroke (particularly atherosclerotic stroke subtypes). Conversely, lipoprotein-a increased the risk for stroke. The ratio of apolipoprotein b to apolipoprotein a-1 was shown to be associated with carotid atheroma. In addition, newer risk factors, including homocysteine and chronic infection (Chlamydia pneumoniae and periodontal disease), are being studied as predictors of ischemic stroke. With these recent advances in the understanding of risk factors, the ability to detect or modify the risk for ischemic stroke should lead to a substantial reduction in the number of people killed or disabled by stroke each year
Effect of vitamin K2 on experimental calcinosis induced by vitamin D2 in rat soft tissue.
Seyama Y, Horiuch M, Hayashi M, et al.
Int J Vitam Nutr Res. 1996; 66(1):36-8.
The effect of vitamin K2 on calcium (Ca) and inorganic phosphorus (P) levels in the aorta and kidney obtained from experimental calcinosis induced by vitamin D2(2.5 x 10(5) I.U./ kg b.w.) of male rats was investigated. A high dose of vitamin K2 (100 mg/kg b.w.) inhibited the increase in the aortic Ca and P or in the renal Ca and P induced by vitamin D2, and a low dose of vitamin K2 (10 mg/kg b.w.) showed the same tendency, but the degree of the efficacy was small. It may be suggested that a high dose of vitamin K2 suppressed experimental calcification of soft tissues induced by vitamin D2. Therefore, a pharmacological dose of vitamin K2 might have a usefulness for the prevention and treatment of arteriosclerosis with calcification
Oxidative damage and mitochondrial decay in aging.
Shigenaga MK, Hagen TM, Ames BN.
Proc Natl Acad Sci U S A. 1994 Nov 8; 91(23):10771-8.
We argue for the critical role of oxidative damage in causing the mitochondrial dysfunction of aging. Oxidants generated by mitochondria appear to be the major source of the oxidative lesions that accumulate with age. Several mitochondrial functions decline with age. The contributing factors include the intrinsic rate of proton leakage across the inner mitochondrial membrane (a correlate of oxidant formation), decreased membrane fluidity, and decreased levels and function of cardiolipin, which supports the function of many of the proteins of the inner mitochondrial membrane. Acetyl-L-carnitine, a high-energy mitochondrial substrate, appears to reverse many age-associated deficits in cellular function, in part by increasing cellular ATP production. Such evidence supports the suggestion that age-associated accumulation of mitochondrial deficits due to oxidative damage is likely to be a major contributor to cellular, tissue, and organismal aging
A possible role of coenzyme Q10 in the etiology and treatment of Parkinson's disease.
Shults CW, Haas RH, Beal MF.
Biofactors. 1999; 9(2-4):267-72.
Parkinson's disease (PD) is a degenerative neurological disorder. Recent studies have demonstrated reduced activity of complex I of the electron transport chain in brain and platelets from patients with PD. Platelet mitochondria from parkinsonian patients were found to have lower levels of coenzyme Q10 (CoQ10) than mitochondria from age/sex-matched controls. There was a strong correlation between the levels of CoQ10 and the activities of complexes I and II/III. Oral CoQ10 was found to protect the nigrostriatal dopaminergic system in one-year-old mice treated with MPTP, a toxin injurious to the nigrostriatal dopaminergic system. We further found that oral CoQ10 was well absorbed in parkinsonian patients and caused a trend toward increased complex I activity. These data suggest that CoQ10 may play a role in cellular dysfunction found in PD and may be a potential protective agent for parkinsonian patients
Acetyl-L-carnitine deficiency as a cause of altered nerve myo-inositol content, Na,K-ATPase activity, and motor conduction velocity in the streptozotocin-diabetic rat.
Stevens MJ, Lattimer SA, Feldman EL, et al.
Metabolism. 1996 Jul; 45(7):865-72.
Defective metabolism of long-chain fatty acids and/or their accumulation in nerve may impair nerve function in diabetes by altering plasma or mitochondrial membrane integrity and perturbing intracellular metabolism and energy production. Carnitine and its acetylated derivatives such as acetyl-L-carnitine (ALC) promote fatty acid beta-oxidation in liver and prevent motor nerve conduction velocity (MNCV) slowing in diabetic rats. Neither the presence nor the possible implications of putative ALC deficiency have been definitively established in diabetic nerve. This study explored sciatic nerve ALC levels and the dose-dependent effects of ALC replacement on sciatic nerve metabolites, Na,K-ATPase, and MNCV after 2 and 4 weeks of streptozotocin-induced diabetes (STZ-D) in the rat. ALC treatment that increased nerve ALC levels delayed (to 4 weeks) but did not prevent nerve myo-inositol (MI) depletion, but prevented MNCV slowing and decreased ouabain-sensitive (but not -insensitive) ATPase activity in a dose-dependent fashion. However, ouabain-sensitive ATPase activity was also corrected by subtherapeutic doses of ALC that did not increase nerve ALC or affect MNCV. These data implicate nerve ALC depletion in diabetes as a factor contributing to alterations in nerve intermediary and energy metabolism and impulse conduction in diabetes, but suggest that these alterations may be differentially affected by various degrees of ALC depletion
Structure-activity relationships of flavonoids and the induction of granulocytic- or monocytic-differentiation in HL60 human myeloid leukemia cells.
Takahashi T, Kobori M, Shinmoto H, et al.
Biosci Biotechnol Biochem. 1998 Nov; 62(11):2199-204.
The flavones apigenin and luteolin strongly inhibited the growth of HL60 cells and induced morphological differentiation into granulocytes. The flavonol quercetin inhibited the cell growth and induced a differentiation marker, i.e., NBT reducing ability. However quercetin-treated cells were not morphologically differentiated into granulocytes. The chalcone phloretin weakly induced NBT reducing ability and a marker of monocytic differentiation alpha-naphthyl butyrate esterase activity in the cells. Quercetin and phloretin appeared to induce the differentiation of HL60 cells into monocytes. The proportion of alpha-naphthyl butyrate esterase-positive cells induced by genistein was less than that of the NBT-positive cells. Some of the nuclei in genistein-treated HL60 cells morphologically changed. Genistein must have induced both granulocytic and monocytic differentiation of HL60 cells. The flavonols galangin and kaempferol, which had fewer hydroxyl group(s) in the B-ring than quercetin, and the flavanone naringenin inhibited the growth but did not induce the differentiation of HL60 cells
Ellagic acid binding to DNA as a possible mechanism for its antimutagenic and anticarcinogenic action.
Cancer Lett. 1986 Mar; 30(3):329-36.
Ellagic acid (EA), a plant phenol, is reported to possess antimutagenic and anticarcinogenic activity. In the present study, explants of esophagus, trachea, colon, forestomach and bladder from young male Sprague-Dawley rats were incubated in medium containing [3H]EA (4.5 mu Ci/ml) for 24 h at 37 degrees C. DNA from these explants was extracted, purified and quantitated to determine [3H]EA binding to the DNA. Significant covalent binding of [3H]EA to DNA occurred in all the explants. Calf thymus DNA incubated in 0.05 M sodium phosphate buffer containing [3H]EA covalently bound [3H]EA in a concentration dependent manner. Furthermore covalent binding of [3H]EA to calf thymus DNA was inhibited by the addition of unlabeled EA that was concentration dependent over a range of 50-150 microM and by the addition of unlabeled adenosine, cytidine, guanosine or thymidine at a concentration of 1.0 mM. These results suggest that one of the mechanisms by which EA inhibits mutagenesis and carcinogenesis is by forming adducts with DNA, thus masking binding sites to be occupied by the mutagen or carcinogen
[Cytokine secretion in whole blood of healthy subjects following oral administration of Urtica dioica L. plant extract].
Teucher T, Obertreis B, Ruttkowski T, et al.
Arzneimittelforschung. 1996 Sep; 46(9):906-10.
Twenty healthy volunteers ingested for 21 days 2 capsules b.i.d. of an IDS 23/1 containing nettle leaf extract (Rheuma-Hek). Before and after 7 and 21 days the basal and the lipopolysaccharide (LPS) stimulated tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6) concentrations were measured ex vivo. In vitro the effects of IDS 23/1 on the release of these cytokines were determined. Additionally basal interleukin-4 (IL-4) and interleukin-10 (IL-10) levels were recorded. Orally taken the test drug has ex vivo no effect on basal levels of TNF-alpha, IL-1 beta, IL-4, IL-6 or IL-10 which were always below detection limits. After 7 and 21 days ingestion ex vivo a decrease of LPS stimulated TNF-alpha release of 14.6 and 24.0%, respectively, was observed. IL-1 beta was reduced for 19.2 and 39.3%. In vitro IDS 23/1 added to whole blood resulted in an exceeded inhibition of LPS stimulated TNF-alpha and IL-1 beta secretion which correlated with the duration of the drug ingestion. Using the highest tested IDS 23/1 concentration the inhibition reached 50.5 (day 0) to 79.5% (day 21) for TNF-alpha and 90.0 (day 0) to 99.2% (day 21) for IL-1 beta, respectively. IDS 23/1 induced a pronounced release of IL-6 in absence of LPS only in vitro. The detected IL-6 concentrations were comparable to those after LPS stimulation, additive effects could not be observed. The absence of detectable IL-6 concentrations in whole blood ex vivo after oral ingestion of the tested drug as well as the differences in the inhibition patterns for TNF-alpha and IL-1 beta ex vivo and ex vivo in vitro suggest that the extract contains different pharmacological effective compounds with varying bioavailabilities
Inhibition of liver fibrosis by ellagic acid.
Thresiamma KC, Kuttan R.
Indian J Physiol Pharmacol. 1996 Oct; 40(4):363-6.
Chronic administration of carbon tetrachloride in liquid paraffin (1.7) ip; 0.15 ml, (20 doses) has been found to produce severe hepatotoxicity, as seen from the elevated levels of serum and liver glutamate-pyruvate transaminase, alkaline phosphatase and lipid peroxides. The chronic administration of carbon tetrachloride was also found to produce liver fibrosis as seen from pathological analysis as well as elevated liver-hydroxy proline. Oral administration of ellagic acid was found to significantly reduce the elevated levels of enzymes, lipid peroxide and liver hydroxy proline in these animals and rectified liver pathology. These results indicate that ellagic acid administration orally can circumvent the carbon tetrachloride toxicity and subsequent fibrosis
Evidence by in vivo and in vitro studies that binding of pycnogenols to elastin affects its rate of degradation by elastases.
Tixier JM, Godeau G, Robert AM, et al.
Biochem Pharmacol. 1984 Dec 15; 33(24):3933-9.
Procyanidol oligomers and (+) catechin bound to insoluble elastin markedly affect its rate of degradation by elastases. Insoluble elastin pretreated with procyanidol oligomers (PCO) was resistant to the hydrolysis induced by both porcine pancreatic and human leukocyte elastases. The quantitative adsorption of pancreatic elastase was similar on either untreated or PCO-treated elastin suggesting that the binding of this compound to elastin increases the non-productive catalytic sites of elastase molecules. (+) Catechin-insoluble elastin complexes were partially resistant to the degradation induced by human leukocyte elastase but were hydrolysed at the same rate as untreated samples by a constant amount of pancreatic elastase. In addition, the coacervation profile of kappa-elastin peptides as a function of temperature is greatly modified in presence of these flavonoids. We conclusively evidenced that PCOs bind to skin elastic fibres when injected intradermally into young rabbits. As a result, these elastic fibres were found more resistant to the hydrolytic action of porcine pancreatic elastase when injected to the same site. These in vivo studies further emphasized the potential effect of these compounds in preventing elastin degradation by elastase(s) as occurred in inflammatory processes
Induction of TIMP-1 expression in rat hepatic stellate cells and hepatocytes: a new role for homocysteine in liver fibrosis.
Torres L, Garcia-Trevijano ER, Rodriguez JA, et al.
Biochim Biophys Acta. 1999 Sep 20; 1455(1):12-22.
Elevated plasma levels of homocysteine have been shown to interfere with normal cell function in a variety of tissues and organs, such as the vascular wall and the liver. However, the molecular mechanisms behind homocysteine effects are not completely understood. In order to better characterize the cellular effects of homocysteine, we have searched for changes in gene expression induced by this amino acid. Our results show that homocysteine is able to induce the expression and synthesis of the tissue inhibitor of metalloproteinases-1 (TIMP-1) in a variety of cell types ranging from vascular smooth muscle cells to hepatocytes, HepG2 cells and hepatic stellate cells. In this latter cell type, homocysteine also stimulated alpha 1(I) procollagen mRNA expression. TIMP-1 induction by homocysteine appears to be mediated by its thiol group. Additionally, we demonstrate that homocysteine is able to promote activating protein-1 (AP-1) binding activity, which has been shown to be critical for TIMP-1 induction. Our findings suggest that homocysteine may alter extracellular matrix homeostasis on diverse tissular backgrounds besides the vascular wall. The liver could be considered as another target for such action of homocysteine. Consequently, the elevated plasma levels of this amino acid found in different pathological or nutritional circumstances may cooperate with other agents, such as ethanol, in the onset of liver fibrosis
Micronutrients and the risk of colorectal adenomas.
Tseng M, Murray SC, Kupper LL, et al.
Am J Epidemiol. 1996 Dec 1; 144(11):1005-14.
Recent studies suggest that micronutrients, especially folate, calcium, iron, and antioxidant vitamins, affect the risk of colorectal neoplasia. The objective of this case-control study was to examine the association between these micronutrients and the risk of colorectal adenomas. The study was based on 236 cases with adenomatous polyps or cancer and 409 controls, all colonoscopy patients at University of North Carolina Hospitals between July 1988 and March 1991. After colonoscopy, subjects were interviewed using a semi-quantitative food frequency questionnaire, and average daily nutrient intakes were calculated. Sex-specific odds ratios relative to the lowest quartile of intake for each micronutrient were determined using unconditional logistic regression while adjusting for a number of potential confounders. In women, folate, iron, and vitamin C were inversely related to the risk of adenomas. Folate appeared to be most protective, with women in the highest quartile only 40% as likely to develop adenomas compared with women in the lowest (odds ratio = 0.39, 95% confidence interval 0.15-1.01). In men, greater vitamin E and calcium intakes were associated with reduced risk of adenomas, with vitamin E showing the strongest inverse association. Men in the highest vitamin E quartile had a risk of 0.35 (95% confidence interval 0.14-0.92) relative to those in the lowest. These study results support previous research findings that selected micronutrients protect against colorectal neoplasia
Metabolism of S-adenosylmethionine in rat hepatocytes: transfer of methyl group from S-adenosylmethionine by methyltransferase reactions.
Tsukada K, Abe T, Kuwahata T, et al.
Life Sci. 1985 Aug 19; 37(7):665-72.
Treatment of rats with a methionine diet leads not only to a marked increase of S-adenosylmethionine synthetase in liver, but also to the increase of glycine, guanidoacetate and betaine-homocysteine methyltransferases. The activity of tRNA methyltransferase decreased with the increased amounts of methionine in the diets. However, the activities of phospholipids and S-adenosylmethionine-homocysteine methyltransferases did not show any significant change. When hepatocarcinogenesis induced by 2-fluorenylacetamide progresses, the activities of glycine and guanidoacetate methyltransferases in rat liver decreased, and could not be detected in tumorous area 8 months after treatment. The levels of S-adenosylmethionine in the liver also decreased to levels of one-fifth of control animals at 8 months. The uptake and metabolism of [methyl-3H]-methionine and -S-adenosylmethionine have been investigated by in vivo and isolated hepatocytes. The uptake of methionine and transfer of methyl group to phospholipid in the cells by methionine were remarkably higher than those by S-adenosylmethionine. These results indicate that phospholipids in hepatocytes accept methyl group from S-adenosylmethionine immediately, when it is synthesized from methionine, before mixing its pool in the cells
Vitamin E succinate induces Fas-mediated apoptosis in estrogen receptor-negative human breast cancer cells.
Turley JM, Fu T, Ruscetti FW, et al.
Cancer Res. 1997 Mar 1; 57(5):881-90.
Vitamin E succinate (VES), a derivative of the fat-soluble vitamin D-alpha-tocopherol (vitamin E), inhibited growth and induced apoptotic cell death of estrogen receptor-negative human breast cancer cells. VES-induced apoptosis in MDA-MB-231 and SKBR-3 cells occurred through a Fas pathway. Total protein levels of the Fas receptor (Fas; APO-1/CD-95) and the Fas ligand (Fas-L) were increased following VES treatment. In addition, VES increased cell surface Fas expression. Fas-neutralizing antibodies and Fas-L antisense oligonucleotides blocked VES-induced apoptosis. The presence of Fas-L antisense oligonucleotides also completely blocked the VES-mediated increase in Fas-L protein expression. These data indicate a role for Fas signaling in VES-mediated apoptotic cell death of human breast cancer cells. These findings also suggest that VES may be of clinical use in the treatment of aggressive human breast cancers, particularly those that are refractory to antiestrogen therapy
Glutathione and alpha-lipoate in diabetic rats: nerve function, blood flow and oxidative state.
van Dam PS, van Asbeck BS, Van Oirschot JF, et al.
Eur J Clin Invest. 2001 May; 31(5):417-24.
BACKGROUND: Increased oxidative stress is considered to be a causal factor in the development of diabetic complications, among which peripheral neuropathy. The pathophysiology of nerve dysfunction in diabetes has been explained both by reduced endoneurial microcirculation and alterations in endoneurial metabolism. It is unclear whether antioxidants primarily improve nerve blood flow or normalise systemic or endoneurial oxidative metabolism. Therefore, we evaluated the effects of the antioxidants glutathione and alpha-lipoic acid on both nerve microcirculation and the antioxidative capacity and lipid peroxidation in experimentally diabetic rats. MATERIALS AND METHODS: Streptozotocin-diabetic rats were treated with different doses of alpha-lipoic acid, reduced glutathione or placebo, and were compared with nondiabetic controls. We measured systemic and endoneurial antioxidants, malondialdehyde and whole blood hydrogen peroxide. Furthermore, we evaluated sciatic and tibial motor and sensory nerve conduction velocity, caudal nerve conduction velocity, and assessed sciatic nerve blood flow and vascular resistance by Laser-Doppler flowmetry. RESULTS: We observed a rise in erythrocyte glutathione by 27 % (P < 0.05), and a trend towards decreased plasma malondialdehyde in alpha-lipoic acid, but not in glutathione-treated animals in comparison with the placebo group. Simultaneously, sciatic nerve blood flow and vascular resistance were improved by daily alpha-lipoic acid administration by 38% (P < 0.05). Peripheral nerve conduction velocity and endoneurial glutathione were not significantly influenced by antioxidant treatment. CONCLUSIONS: Only minor beneficial effects of alpha-lipoic acid on nerve blood flow and oxidative state occur at the given doses; these effects were insufficient to improve nerve conduction deficits
Homocystinuria: what about mild hyperhomocysteinaemia?
van den BM, Boers GH.
Postgrad Med J. 1996 Sep; 72(851):513-8.
Hyperhomocysteinaemia is associated with an increased risk of atherosclerotic vascular disease and thromboembolism, in both men and women. A variety of conditions can lead to elevated homocysteine levels, but the relation between high levels and vascular disease is present regardless of the underlying cause. Pooled data from a large number of studies demonstrate that mild hyperhomocysteinaemia after a standard methionine load is present in 21% of young patients with coronary artery disease, in 24% of patients with cerebrovascular disease, and in 32% of patients with peripheral vascular disease. From such data an odds ratio of 13.0 (95% confidence interval 5.9 to 28.1), as an estimate of the relative risk of vascular disease at a young age, can be calculated in subjects with an abnormal response to methionine loading. Furthermore, mild hyperhomo-cysteinaemia can lead to a two- or three-fold increase in the risk of recurrent venous thrombosis. Elevated homocysteine levels can be reduced to normal in virtually all cases by simple and safe treatment with vitamin B6, folic acid, and betaine, each of which is involved in methionine metabolism. A clinically beneficial effect of such an intervention, currently under investigation, would make large-scale screening for this risk factor mandatory
Low plasma ascorbic acid independently predicts the presence of an unstable coronary syndrome.
Vita JA, Keaney JF, Jr., Raby KE, et al.
J Am Coll Cardiol. 1998 Apr; 31(5):980-6.
OBJECTIVES: This study sought to investigate the relations between plasma antioxidant status, extent of atherosclerosis and activity of coronary artery disease. BACKGROUND: Previous studies indicate that increased antioxidant intake is associated with decreased coronary disease risk, but the underlying mechanisms remain controversial. METHODS: Plasma samples were obtained from 149 patients undergoing cardiac catheterization (65 with stable angina, 84 with unstable angina or a myocardial infarction within 2 weeks). Twelve plasma antioxidant/oxidant markers were measured and correlated with the extent of atherosclerosis and the presence of an unstable coronary syndrome. RESULTS: By multiple linear regression analysis, age (p < 0.001), diabetes mellitus (p < 0.001), male gender (p < 0.001) and hypercholesterolemia (p = 0.02) were independent predictors of the extent of atherosclerosis. No antioxidant/oxidant marker correlated with the extent of atherosclerosis. However, lower plasma ascorbic acid concentration predicted the presence of an unstable coronary syndrome by multiple logistic regression (odds ratio [OR] 0.59, 95% confidence interval [CI] 0.40 to 0.89, p = 0.01). The severity of atherosclerosis also predicted the presence of an unstable coronary syndrome (OR 1.7, 95% CI 1.14 to 2.47, p = 0.008) when all patients were considered. When only patients with significant coronary disease were considered (at least one stenosis >50%), ascorbic acid concentration (OR 0.56, 95% CI 0.37 to 0.85, p = 0.008) and total plasma thiols (OR 0.52, 95% CI 0.34 to 0.80, p = 0.004) predicted the presence of an unstable coronary syndrome, whereas the extent of atherosclerosis did not. CONCLUSIONS: These data are consistent with the hypothesis that the beneficial effects of antioxidants in coronary artery disease may result, in part, by an influence on lesion activity rather than a reduction in the overall extent of fixed disease
The relationship between boron and magnesium status and bone mineral density in the human: a review.
Volpe SL, Taper LJ, Meacham S.
Magnes Res. 1993 Sep; 6(3):291-6.
Osteoporosis is a disease that characteristically afflicts postmenopausal women. It is estimated that millions of people are plagued yearly with this debilitating disease. Associated health care costs are in the billions of dollars, annually. Much research has been conducted in the area of osteoporosis and mineral supplementation, mainly focusing on calcium and vitamin D. Nonetheless, more recent studies have reported possible improvements in bone mineral density in women who were supplemented with the ultratrace mineral, boron. Boron may play a role in bone metabolism, but its role is most likely to be associated with its interactions with other minerals and vitamins such as calcium, magnesium and vitamin D. Although the focus of this review will be to discuss the interactive role of boron with magnesium and bone metabolism, some discussion of its interactive role with vitamin D is also necessary
Methyl groups in carcinogenesis: effects on DNA methylation and gene expression.
Wainfan E, Poirier LA.
Cancer Res. 1992 Apr 1; 52(7 Suppl):2071s-7s.
Lipotrope-deficient (methyl-deficient) diets cause fatty livers and increased liver-cell turnover and promote carcinogenesis in rodents. In rats prolonged intake of methyl-deficient diets results in liver tumor development. The mechanisms responsible for the cancer-promoting and carcinogenic properties of this deficiency remain unclear. The results of the experiments described here lend support to the hypothesis that intake of such a diet, by causing depletion of S-adenosylmethionine pools, results in DNA hypomethylation, which in turn leads to changes in expression of genes that may have key roles in regulation of growth. In livers of rats fed a severely methyl-deficient diet (MDD), lowered pools of S-adenosylmethionine and hypomethylated DNA were observed within 1 week. The extent of DNA hypomethylation increased when MDD was fed for longer periods. The decreases in overall levels of DNA methylation were accompanied by simultaneous alterations in gene expression, yielding patterns that closely resembled those reported to occur in livers of animals exposed to cancer-promoting chemicals and in hepatomas. Northern blot analysis of polyadenylated RNAs from livers of rats fed control or deficient diets showed that, after 1 week of MDD intake, there were large increases in levels of mRNAs for the c-myc and c-fos oncogenes, somewhat smaller increases in c-Ha-ras mRNA, and virtually no change in levels of c-Ki-ras mRNA. In contrast, mRNAs for epidermal growth factor receptor decreased significantly. The elevated levels of expression of the c-myc, c-fos, and c-Ha-ras genes were accompanied by selective changes in patterns of methylation within the sequences specifying these genes. Changes in DNA methylation and in gene expression induced in livers of rats fed MDD for 1 month were gradually reversed after restoration of an adequate diet. In hepatomas induced by prolonged dietary methyl deficiency, methylation patterns of c-Ki-ras and c-Ha-ras were abnormal. Although human diets are unlikely to be as severely methyl deficient as those used in these experiments, in some parts of the world intake of diets that are low in methionine and choline and contaminated with mycotoxins, such as aflatoxin, are common. Even in industrialized nations, deficiencies of folic acid and vitamin B12 are not uncommon and are exacerbated by some therapeutic agents and by substance abuse. Thus, it seems possible that interactions of diet and contaminants or drugs, by inducing changes in DNA methylation and aberrant gene expression, may contribute to cancer causation in humans
Dietary glucarate as anti-promoter of 7,12-dimethylbenz[a]anthracene-induced mammary tumorigenesis.
Walaszek Z, Hanausek-Walaszek M, Minton JP, et al.
Carcinogenesis. 1986 Sep; 7(9):1463-6.
Using as a criterion the inhibition of serum beta-glucuronidase activity, dietary calcium D-glucarate is shown to serve as an efficient slow-release source in vivo of D-glucaro-1,4-lactone, the potent endogenous inhibitor of this enzyme. Using the 7,12-dimethylbenz[a]anthracene model of mammary tumor induction in rats it is shown for the first time that feeding the rats calcium D-glucarate-supplemented diet after treatment with the carcinogen, inhibits tumor development by over 70%. Supportive evidence is presented for the theory that calcium D-glucarate inhibits or delays the promotion phase of mammary carcinogenesis by lowering endogenous levels of estradiol and precursors of 17-ketosteroids. Therefore, dietary glucarate can be used to lower blood and tissue levels of beta-glucuronidase, and in turn of those carcinogens and promoting agents which are excreted, at least in part, as glucuronide conjugates
Betaine:homocysteine methyltransferase--a new assay for the liver enzyme and its absence from human skin fibroblasts and peripheral blood lymphocytes.
Wang JA, Dudman NP, Lynch J, et al.
Clin Chim Acta. 1991 Dec 31; 204(1-3):239-49.
Chronic elevation of plasma homocysteine is associated with increased atherogenesis and thrombosis, and can be lowered by betaine (N,N,N-trimethylglycine) treatment which is thought to stimulate activity of the enzyme betaine:homocysteine methyltransferase. We have developed a new assay for this enzyme, in which the products of the enzyme-catalysed reaction between betaine and homocysteine are oxidised by performic acid before being separated and quantified by amino acid analysis. This assay confirmed that human liver contains abundant betaine:homocysteine methyltransferase (33.4 nmol/h/mg protein at 37 degrees C, pH 7.4). Chicken and lamb livers also contain the enzyme, with respective activities of 50.4 and 6.2 nmol/h/mg protein. However, phytohaemagglutinin-stimulated human peripheral blood lymphocytes and cultured human skin fibroblasts contained no detectable betaine:homocysteine methyltransferase (less than 1.4 nmol/h/mg protein), even after cells were pre-cultured in media designed to stimulate production of the enzyme. The results emphasize the importance of the liver in mediating the lowering of elevated circulating homocysteine by betaine
Randomized, double-blind, placebo-controlled study of the preventive effect of supplemental oral vitamin C on attenuation of development of nitrate tolerance.
Watanabe H, Kakihana M, Ohtsuka S, et al.
J Am Coll Cardiol. 1998 May; 31(6):1323-9.
OBJECTIVES: This study sought to evaluate the preventive effect of vitamin C, an antioxidant, on the development of nitrate tolerance. BACKGROUND: Decreased intracellular production of cyclic guanosine monophosphate (cGMP) is a mechanism of nitrate tolerance, and increased superoxide levels and reduced activation of guanylate cyclase have been observed in vitro. METHODS: In this double-blind, placebo-controlled study, 24 normal volunteers and 24 patients with ischemic heart disease (IHD) were randomized to receive either vitamin C (2 g three times daily [vitamin C group, n=12]) or placebo (placebo group, n=12). The vasodilator response to nitroglycerin was assessed with forearm plethysmography by measuring the change in FBF before and 5 min after sublingual administration of 0.3 mg of nitroglycerin. Blood samples were simultaneously obtained to measure platelet cGMP levels. FBF was measured, and blood sampling was performed serially at baseline (day 0), 3 days after administration of vitamin C or placebo (day 3) and 3 days after application of a 10-mg/24-h nitroglycerin tape concomitantly with oral vitamin C or placebo (day 6). RESULTS: There were no differences between the vitamin C and placebo groups in percent increases in FBF (%FBF) or platelet cGMP levels (%cGMP) after administration of sublingual nitroglycerin on day O (%FBF: normal volunteers 31+/-8 vs. 32+/-10; patients with IHD 32+/-9 vs. 32+/-8; %cGMP: normal volunteers 37+/-9 vs. 39+/-10; patients with IHD 38+/-10 vs. 39+/-10 [vitamin C group vs. placebo group]) or day 3 (%FBF: normal volunteers 32+/-9 vs. 33+/-9; patients with IHD 31+/-10 vs. 31+/-10; %cGMP: normal volunteers 36+/-8 vs. 37+/-9; patients with IHD 39+/-11 vs. 38+/-10 [vitamin C group vs. placebo group]). The %FBF and %cGMP in the placebo group were significantly lower on day 6 than in the vitamin C group (%FBF: normal volunteers 30+/-8 vs. 19 4, p < 0.01; patients with IHD 29+/-9 vs. 17+/-6, p < 0.01; %cGMP: normal volunteers 36 10 vs. 17+/-6, p < 0.01; patients with IHD 37+/-11 vs. 15+/-5, p < 0.01 [vitamin C group vs. placebo group]). CONCLUSIONS: These results indicate that combination therapy with vitamin C is potentially useful for preventing the development of nitrate tolerance
Dehydroepiandrosterone and diseases of aging.
Watson RR, Huls A, Araghinikuam M, et al.
Drugs Aging. 1996 Oct; 9(4):274-91.
Dehydroepiandrosterone (DHEA; prasterone) is a major adrenal hormone with no well accepted function. In both animals and humans, low DHEA levels occur with the development of a number of the problems of aging: immunosenesence, increased mortality, increased incidence of several cancers, loss of sleep, decreased feelings of well-being, osteoporosis and atherosclerosis. DHEA replacement in aged mice significantly normalised immunosenescence, suggesting that this hormone plays a key role in aging and immune regulation in mice. Similarly, osteoclasts and lymphoid cells were stimulated by DHEA replacement, an effect that may delay osteoporosis. Recent studies do not support the original suggestion that low serum DHEA levels are associated with Alzheimer's disease and other forms of cognitive dysfunction in the elderly. As DHEA modulates energy metabolism, low levels should affect lipogenesis and gluconeogenesis, increasing the risk of diabetes mellitus and heart disease. Most of the effects of DHEA replacement have been extrapolated from epidemiological or animal model studies, and need to be tested in human trials. Studies that have been conducted in humans show essentially no toxicity of DHEA treatment at dosages that restore serum levels, with evidence of normalisation in some aging physiological systems. Thus, DHEA deficiency may expedite the development of some diseases that are common in the elderly
Vitamin and calcium supplement use is associated with decreased adenoma recurrence in patients with a previous history of neoplasia.
Whelan RL, Horvath KD, Gleason NR, et al.
Dis Colon Rectum. 1999 Feb; 42(2):212-7.
INTRODUCTION: Although some have suggested that certain vitamins or calcium supplements may reduce adenoma recurrence, our own prior retrospective study found no such effects. The purpose of this case-control study was to further investigate whether regular vitamin or calcium supplement intake influenced the incidence of recurrent adenomatous polyps in patients with previous neoplasia who were undergoing follow-up colonoscopy. METHODS: This study enrolled 1,162 patients who underwent colonoscopy by one of three surgeons at Columbia-Presbyterian Medical Center in New York City between March 1993 and February 1997. Of these patients 448 (250 males) had a previous diagnosis of colorectal neoplasia (cancer, adenomas, or dysplasia). Of these, 183 (40.8 percent) had an adenoma at the index colonoscopy. Information was collected on personal and family history of colonic diseases, cigarette smoking, medication, and vitamin and micronutrient supplement usage on a questionnaire that was completed by the patients before the colonoscopy. Odds ratios were obtained by unconditional logistic regression analysis, adjusting for age and gender, and used adenoma recurrence at index colonoscopy as the outcome. RESULTS: The mean interval between colonoscopic examinations was 37 months for the recurrent adenoma group and 38 months for the nonrecurrent group of patients (P = not significant). In this case-control study we found a protective effect for the use of vitamin supplements in general (any vitamin) on the recurrence of adenomas (odds ratio, 0.41; 95 percent confidence interval, 0.27-0.61). Specifically, this protective effect was observed for the use of multivitamins (odds ratio, 0.47; 95 percent confidence interval, 0.31-0.72), vitamin E (odds ratio, 0.62; 95 percent confidence interval, 0.39-0.98), and for calcium supplementation (odds ratio, 0.51; 95 percent confidence interval, 0.27-0.96). Nonsignificant protective effects were noted for carotene/vitamin A, vitamin D, and vitamin C. CONCLUSIONS: The use of multivitamins, vitamin E, and calcium supplements were found to be associated with a lower incidence of recurrent adenomas in a population of patients with history of previous colonic neoplasia. Prospective, randomized trials are needed to better assess the impact of these agents and to determine whether the use of these supplements is associated with a protective effect against recurrent adenomas
Homocystinuria due to cystathionine beta-synthase deficiency--the effects of betaine treatment in pyridoxine-responsive patients.
Wilcken DE, Dudman NP, Tyrrell PA.
Metabolism. 1985 Dec; 34(12):1115-21.
Homocystinuria due to cystathionine beta-synthase deficiency may be responsive to pyridoxine, a precursor of the cofactor pyridoxal phosphate, and the amount of residual enzyme activity present is the probable determinant of this. In six treated pyridoxine-responsive patients whose biochemical control of fasting plasma amino acid levels appeared optimal, we assessed the effects on plasma amino acids of standard oral methionine loads (4g/m2 of body area) before and after adding betaine (trimethylglycine) 6 g/d, to the treatment regimen of pyridoxine and folic acid. Our aim was to define the capacity of these patients to metabolize methionine and to determine whether betaine would effect a reduction in postload homocysteine levels. During the 24 hours after the methionine challenge all patients had higher plasma methionine and homocysteine and lower cysteine than did 17 normal subjects. After betaine these homocysteine responses were reduced to near normal, and there was a trend toward increased methionine. There was a direct correlation between premethionine fasting homocysteine and mean homocysteine responses during the 24 hours following the methionine load, both before (r = 0.79) and after betaine (r = 0.71). Betaine also increased plasma cysteine levels in patients with the more severe biochemical abnormalities. After betaine there were modest increases in plasma serine (mean increase 25%; P less than 0.025). Since the vascular complications of homocystinuria are related to increased plasma homocysteine, betaine therapy may reduce this risk in patients receiving a standard pyridoxine and folic acid regimen in whom there are abnormal homocysteine responses after a standard methionine load
Dehydroepiandrosterone (DHEA) treatment of depression.
Wolkowitz OM, Reus VI, Roberts E, et al.
Biol Psychiatry. 1997 Feb 1; 41(3):311-8.
Dehydroepiandrosterone (DHEA) and its sulfate, DHEA-S, are plentiful adrenal steroid hormones that decrease with aging and may have significant neuropsychiatric effects. In this study, six middle-aged and elderly patients with major depression and low basal plasma DHEA f1p4or DHEA-S levels were openly administered DHEA (30-90 mg/d x 4 weeks) in doses sufficient to achieve circulating plasma levels observed in younger healthy individuals. Depression ratings, as well as aspects of memory performance significantly improved. One treatment-resistant patient received extended treatment with DHEA for 6 months: her depression ratings improved 48-72% and her semantic memory performance improved 63%. These measures returned to baseline after treatment ended. In both studies, improvements in depression ratings and memory performance were directly related to increases in plasma levels of DHEA and DHEA-S and to increases in their ratios with plasma cortisol levels. These preliminary data suggest DHEA may have antidepressant and promemory effects and should encourage double-blind trials in depressed patients
Signal pathways involved in apigenin inhibition of growth and induction of apoptosis of human anaplastic thyroid cancer cells (ARO).
Yin F, Giuliano AE, Van Herle AJ.
Anticancer Res. 1999 Sep; 19(5B):4297-303.
Recently we demonstrated that several flavonoids can inhibit the proliferation of certain human thyroid cancer cell lines. Among the flavonoids tested, apigenin and luteolin are the most effective inhibitors of these tumor cell lines. In the present study, we investigated the signal transduction mechanism associated with the growth inhibitory effect of apigenin, using a human anaplastic thyroid carcinoma cell line, ARO (UCLA RO-81-A-1). Using Western blot method, it was shown that the inhibitory effect of apigenin on ARO cell proliferation is associated with an inhibition of both EGFR tyrosine autophosphorylation and phosphorylation of its downstream effector mitogen activated protein (MAP) kinase. Protein levels of these signaling molecules were not affected. The inhibitor of phosphorylation by apigenin occurred within 30 min and continued for 4 h. A dose-dependent inhibition was demonstrable ranging from 12.5 microM to 50 microM. The level of phosphorylated c-Myc, a nuclear substrate for MAPK, was depressed from 16-48 h after apigenin treatment, finally leading to a programmed cell death involving DNA fragmentation. Furthermore, treatment with apigenin resulted in the inhibition of both anchorage-dependent and anchorage-independent thyroid cancer cell growth. In summary, apigenin is a promising inhibitor of signal transduction pathways that regulate the growth (anchorage-dependent and independent) and survival of human anaplastic thyroid cancer cells. Apigenin may provide a new approach for the treatment of human anaplastic thyroid carcinoma for which no effective therapy is presently available
Prediagnostic levels of serum beta-cryptoxanthin and retinol predict smoking-related lung cancer risk in Shanghai, China.
Yuan JM, Ross RK, Chu XD, et al.
Cancer Epidemiol Biomarkers Prev. 2001 Jul; 10(7):767-73.
Higher blood levels of beta-carotene have been found to be associated with reduced risk of lung cancer, but large intervention trials have failed to demonstrate reduced lung cancer incidence after prolonged high-dose beta-carotene supplementation. Data on blood levels of specific carotenoids other than beta-carotene in relation to lung cancer are scarce. Little is known about the relationship between prediagnostic serum levels of carotenoids, retinol, and tocopherols, and risk of lung cancer especially in non-Western populations. Between January 1986 and September 1989, 18,244 men ages 45-64 years participated in a prospective study of diet and cancer in Shanghai, China. Information on tobacco smoking and other lifestyle factors was obtained through in-person interviews. A serum sample was collected from each study participant at baseline. During the first 12 years of follow-up, 209 lung cancer cases, excluding those diagnosed within 2 years of enrollment, were identified. For each cancer case, three cancer-free control subjects were randomly selected from the cohort and matched to the index case by age (within 2 years), month and year of blood sample collection, and neighborhood of residence. Serum concentrations of retinol, alpha- and gamma-tocopherols, and specific carotenoids including alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, and lutein/zeaxanthin were determined on the 209 cases and 622 matched controls by high-performance liquid chromatography methods. A high prediagnostic serum level of beta-cryptoxanthin was significantly associated with reduced risk of lung cancer; relative to the lowest quartile, the smoking-adjusted relative risks (95% confidence intervals) for the 2nd, 3rd, and 4th quartile categories were 0.72 (0.41-1.26), 0.42 (0.21-0.84), and 0.45 (0.22-0.92), respectively (P for trend = 0.02). Increased serum levels of other specific carotenoids including alpha-carotene, beta-carotene, lycopene, and lutein/zeaxanthin were related to reduced risk of lung cancer although the inverse associations were no longer statistically significant after adjustment for smoking. A statistically significant 37% reduction in risk of lung cancer was noted in smokers with above versus below median level of total carotenoids. Serum retinol levels showed a threshold effect on lung cancer risk. Compared with the lowest quartile (<40 microg/dl), the smoking-adjusted relative risk (95% confidence interval) was 0.60 (0.39-0.92) for men in the 2nd-4th quartiles of retinol values combined; no additional decrease in risk was observed between individuals from the 2nd to 4th quartiles. There were no associations between prediagnostic serum levels of alpha- and gamma-tocopherols and lung cancer (all Ps for trend > or =0.4). The present data indicate that higher prediagnostic serum levels of total carotenoids and beta-cryptoxanthin were associated with lower smoking-related lung cancer risk in middle-aged and older men in Shanghai, China. Low level of serum retinol (with a threshold effect) is associated with increased lung cancer risk in this oriental population
Dietary carotenoids and vitamins A, C, and E and risk of breast cancer.
Zhang S, Hunter DJ, Forman MR, et al.
J Natl Cancer Inst. 1999 Mar 17; 91(6):547-56.
BACKGROUND: Data on intake of specific carotenoids and breast cancer risk are limited. Furthermore, studies of vitamins A, C, and E in relation to breast cancer risk are inconclusive. We have conducted a large, prospective study to evaluate long-term intakes of these nutrients and breast cancer risk. METHODS: We examined, by use of multivariate analysis, associations between intakes of specific carotenoids, vitamins A, C, and E , consumption of fruits and vegetables, and breast cancer risk in a cohort of 83234 women (aged 33-60 years in 1980) who were participating in the Nurses' Health Study. Through 1994, we identified 2697 incident cases of invasive breast cancer (784 premenopausal and 1913 postmenopausal). RESULTS: Intakes of beta-carotene from food and supplements, lutein/zeaxanthin, and vitamin A from foods were weakly inversely associated with breast cancer risk in premenopausal women. Strong inverse associations were found for increasing quintiles of alpha-carotene, beta-carotene, lutein/zeaxanthin, total vitamin C from foods, and total vitamin A among premenopausal women with a positive family history of breast cancer. An inverse association was also found for increasing quintiles of beta-carotene among premenopausal women who consumed 15 g or more of alcohol per day. Premenopausal women who consumed five or more servings per day of fruits and vegetables had modestly lower risk of breast cancer than those who had less than two servings per day (relative risk [RR] = 0.77; 95% confidence interval [CI] = 0.58-1.02); this association was stronger among premenopausal women who had a positive family history of breast cancer (RR = 0.29; 95% CI = 0.13-0.62) or those who consumed 15 g or more of alcohol per day (RR = 0.53; 95% CI = 0.27-1.04). CONCLUSIONS: Consumption of fruits and vegetables high in specific carotenoids and vitamins may reduce premenopausal breast cancer risk