Micronutrients, vitamins, and cancer risk.
Division of Clinical Sciences, Old Medical School, University of Leeds, United Kingdom.
Vitam Horm 1999;57:1-23
There is now considerable evidence that a high intake of fruit and vegetables can decrease the risk of developing cancer. While it is by no means clear how this particular diet alters cancer risk, there is substantial metabolic and experimental evidence to implicate antioxidant micronutrients, The dietary components include some vitamins, such as C and E, the carotenoids, and the flavinoids. In chemical systems, cell culture, and experimental animals, these components have the ability to quench the carcinogenic potential of reactive oxygen species and other carcinogens, such as N-nitrosocompounds. Some of these micronutrients can act synergistically, and high concentrations are often found in tissues, such as the leucocytes and mucosal cells, that are particularly prone to reactive species attack. Experimental systems containing these micronutrients also appear to be able to reduce DNA damage and mutagenesis. However, assessment of individual vitamin intake, as opposed to fruit and vegetable consumption, does not increase the protective association of these components, and the results of intervention studies in man, especially with carotenoids, have been disappointing. We await the results of other clinical trials, but as yet, there is insufficient evidence to recommend supplements of these particular micronutrients for the prevention of cancer. However, it would be prudent to suggest changes in diet that would increase consumption of fruit and vegetables, such as a diet is clearly associated with protection. (131 Refs.)
Hydrogen peroxide suppresses U937 cell death by two different mechanisms depending on its concentration.
Lee BR; Um HD
Yonsei Medical Research Center, Yonsei University College of Medicine, Seoul, Korea.
Exp Cell Res (United States) May 1 1999, 248 (2) p430-8
To investigate the mechanisms of H2O2 adaptation in mammalian cells, we exposed human U937 leukemia cells to 0.05 mM H2O2. This treatment significantly suppressed cell death and DNA fragmentation induced by a subsequent challenge with 1 mM H2O2. A more dramatic protection was observed when cells were pretreated with 0.25 mM H2O2. Pretreatment with either 0.05 or 0.25 mM H2O2 also imparted cells with a survival advantage against serum withdrawal and C2-ceramide treatment. H2O2 was found to be a mediator of cell death induced by serum withdrawal, but not by the addition of C2-ceramide. Interestingly, 0.25 mM H2O2 greatly induced glutathione peroxidase, a H2O2-consuming enzyme, whereas 0.05 mM H2O2 did not. Consistent with observation, pretreatment with 0.25 mM H2O2 resulted in a great reduction of cellular oxidant levels as determined by 2'7'-dichlorofluorescein fluorescence, and it also prevented elevation of oxidant levels upon subsequent challenge with 1 mM H2O2 or with serum withdrawal. These effects were not observed in cells pretreated with 0.05 mM H2O2. The sum of the data indicated that H2O2 suppresses cell death by two different mechanisms depending on its concentration: Relatively high concentrations enhance cellular antioxidant capacity, and lower concentrations block the lethal action of H2O2.
Involvement of N-acetylcysteine-sensitive pathways in ricin-induced apoptotic cell death in U937 cells.
Oda T; Iwaoka J; Komatsu N; Muramatsu T
Division of Biochemistry, Faculty of Fisheries, Nagasaki University, Japan
Biosci Biotechnol Biochem (Japan) Feb 1999, 63 (2) p341-8
We have found that the antioxidant N-acetylcysteine (NAC) strongly inhibited ricin-induced apoptotic cell death in U937 cells (human myeloid leukemia), as judged by cytotoxicity, nuclear morphological change, and DNA fragmentation. Consistent with these observations, a significant depletion of cellular glutathione was observed in ricin-treated cells, and NAC prevented the decrease in cellular glutathione. On the other hand, among the caspase inhibitors tested, Z-Asp-CH2-DCB, which inhibited ricin cytotoxicity, also suppressed ricin-mediated glutathione depletion, while NAC did not affect the generation of caspase-3 like activity in ricin-treated cells. These results suggest that glutathione loss takes place downstream from caspase activation during the ricin-induced apoptotic process. Treatment with a specific inhibitor of glutathione biosynthesis, buthionine sulfoximine (BSO) failed to induce apoptosis, and had no effect on the overall extent of ricin-induced apoptosis, even though the glutathione level was decreased to less than 5% of the control level. However, NAC still protected against ricin-induced apoptosis in the BSO-treated cells. We conclude that glutathione loss is one of several apoptotic changes caused by ricin, but is not a sufficient factor for the progress of apoptosis. NAC may prevent ricin-induced apoptosis through maintaining an intracellular reducing condition by acting as a thiol supplier.
Antioxidant therapy in the prevention of organ dysfunction syndrome and infectious complications after trauma: early results of a prospective randomized study.
Porter JM; Ivatury RR; Azimuddin K; Swami R
The Lincoln Medical Center, Bronx, New York, USA.
Am Surg 1999 May;65(5):478-83
Reactive oxygen species have been implicated in the etiology of multiorgan dysfunction syndrome and infectious complications in trauma patients by either direct cellular toxicity and/or the activation of intracellular signaling pathways. Studies have shown that the antioxidant defenses of the body are decreased in trauma patients; these include glutathione, for which N-acetylcysteine is a precursor, and selenium, which is a cofactor for glutathione. Eighteen trauma patients were prospectively randomized to a control or antioxidant group where they received N-acetylcysteine, selenium, and vitamins C and E for 7 days. As compared with the controls, the antioxidant group showed fewer infectious complications (8 versus 18) and fewer organs dysfunctioning (0 versus 9). There were no deaths in either group. We conclude that these preliminary data may support a role for the use of this antioxidant mixture to decrease the incidence of multiorgan dysfunction syndrome and infectious complications in the severely injured patient. This remains to be confirmed in larger trials.
Impact of trace elements and vitamin supplementation on immunity and infections in institutionalized elderly patients: a randomized controlled trial. MIN. VIT. AOX. geriatric network.
Girodon F; Galan P; Monget AL; Boutron-Ruault MC; Brunet-Lecomte P; Preziosi P; Arnaud J; Manuguerra JC; Herchberg S
Scientific and Technical Institute for Foods and Nutrition, Conservatiore National des Arts et Mettiers, Paris, France.
Arch Intern Med (United States) Apr 12 1999, 159 (7) p748-54
BACKGROUND: Antioxidant supplementation is thought to improve immunity and thereby reduce infectious morbidity. However, few large trials in elderly people have been conducted that include end points for clinical variables.
OBJECTIVE: To determine the effects of long-term daily supplementation with trace elements (zinc sulfate and selenium sulfide) or vitamins (beta carotene, ascorbic acid, and vitamin E) on immunity and the incidence of infections in institutionalized elderly people.
METHODS: This randomized, double-blind, placebo-controlled intervention study included 725 institutionalized elderly patients (>65 years) from 25 geriatric centers in France. Patients received an oral daily supplement of nutritional doses of trace elements (zinc and selenium sulfide) or vitamins (beta carotene, ascorbic acid, and vitamin E) or a placebo within a 2 x 2 factorial design for 2 years.
MAIN OUTCOME MEASURES: Delayed-type hypersensitivity skin response, humoral response to influenza vaccine, and infectious morbidity and mortality.
RESULTS: Correction of specific nutrient deficiencies was observed after 6 months of supplementation and was maintained for the first year, during which there was no effect of any treatment on delayed-type hypersensitivity skin response. Antibody titers after influenza vaccine were higher in groups that received trace elements alone or associated with vitamins, whereas the vitamin group had significantly lower antibody titers (P<.05). The number of patients without respiratory tract infections during the study was higher in groups that received trace elements (P = .06). Supplementation with neither trace elements nor vitamins significantly reduced the incidence of urogenital infections. Survival analysis for the 2 years did not show any differences between the 4 groups.
CONCLUSIONS: Low-dose supplementation of zinc and selenium provides significant improvement in elderly patients by increasing the humoral response after vaccination and could have considerable public health importance by reducing morbidity from respiratory tract infections.
Prevention of recurrent pancreatitis in familial lipoprotein lipase deficiency with high-dose antioxidant therapy.
Heaney AP; Sharer N; Rameh B; Braganza JM; Durrington PN
University of Manchester, Department of Medicine, Manchester Royal Infirmary, United Kingdom.
J Clin Endocrinol Metab (United States) Apr 1999, 84 (4) p1203-5
We describe a dramatic response to antioxidant therapy in three patients with familial lipoprotein lipase deficiency complicated by frequent severe episodes of pancreatitis who had failed to respond to other dietary and pharmacological measures. Antioxidant therapy may be an important advance in the management of this type of patient.
Ascorbate prevents prooxidant effects of urate in oxidation of human low density lipoprotein.
Institute of Biochemistry, SFB Biomembrane Research Center, University of Graz, Austria
FEBS Lett 1999 Mar 12;446(2-3):305-8
Uric acid and ascorbic acid are important low molecular weight antioxidants in plasma. Their interactions and combined effect on Cu(2+)-catalysed oxidation of human low density lipoprotein were studied in vitro. It was found that uric acid alone becomes strongly prooxidant whenever it is added to low density lipoprotein shortly after the start of oxidation (conditional prooxidant). Ascorbic acid, which is present in human plasma at much lower concentrations (20-60 microM) than urate (300-400 microM), is in itself not a conditional prooxidant. Moreover, ascorbate prevents prooxidant effects of urate, when added to oxidising low density lipoprotein simultaneously with urate, even at a 60-fold molar excess of urate over ascorbate. Ascorbate appears to have the same anti-prooxidant effect with other aqueous reductants, which, besides their antioxidant properties, were reported to be conditionally prooxidant. Such interactions between ascorbate and urate may be important in preventing oxidative modification of lipoproteins in the circulation and in other biological fluids.
Anti-oxidant effect of flavonoids on hemoglobin glycosylation.
Asgary S; Naderi G; Sarrafzadegan N; Ghassemi N; Boshtam M; Rafie M; Arefian A
Isfahan University of Med. Sciences, Health Services Cardiovascular Research Center, Isfahan, Iran
Pharm Acta Helv 1999 Feb;73(5):223-6
A high glucose concentration has been found to lead to the glycosylation of amino groups of lysine residue in proteins. The addition of reducing agent not only prevents this reaction but also reverses it. On the other hand, flavonoids which found in plant sources have antioxidant properties. Since the glycosylation of protein is an oxidation reaction, therefore, antioxidants should be able to prevent this reaction. In this study, the best concentration and time to incubate glucose with hemoglobin was investigated. Then the glycosylation degree of hemoglobin in the presence of flavonoids and their absence was measured by means of a colorimetric method. Different concentration of flavonoids (Quercetin, Rutin, Kaempferol) were used. The preventing effect on hemoglobin glycosylation by the three concentrations; 0.5, 5, 10 micrograms/ml was estimated as follows: for Rutin; 11%, 27%, 42%, Quercetin; 3%, 37%, 52%, Kaempferol; 10%, 12%, 15% respectively. So, the in vivo effect should be investigated and then plants that containing flavonoids can be utilized to prevent or treat complication of diabetes.
Inhibition of copper-induced LDL oxidation by vitamin C is associated with decreased copper-binding to LDL and 2-oxo-histidine formation.
Retsky KL; Chen K; Zeind J; Frei B
The Evans Memorial Department of Medicine, Whitaker Cardiovascular Institute, Boston University School of Medicine, MA, USA.
Free Radic Biol Med (United States) Jan 1999, 26 (1-2) p90-8
Oxidatively modified low-density lipoprotein (LDL) has numerous atherogenic properties, and antioxidants that can prevent LDL oxidation may act as antiatherogens. We have previously shown that vitamin C (L-ascorbic acid, AA) and its two-electron oxidation product dehydro-L-ascorbic acid (DHA) strongly inhibit copper (Cu)-induced LDL oxidation. These findings are unusual, as AA is known to act not only as an antioxidant, but also a pro-oxidant in the presence of transition metal ions in vitro, and DHA has no known reducing capacity. Here we report that human LDL (0.4 mg protein/ml) incubated with 40 microM Cu2+ binds 28.0 +/- 3.3 Cu ions per LDL particle (mean +/- SD, n = 10). Co-incubation of LDL with AA or DHA led to the time- and concentration-dependent release of up to 70% of bound Cu, which was associated with the inhibition of LDL oxidation. Incubation of LDL with Cu and AA or DHA also led to the time-dependent formation of 2-oxo-histidine, an oxidized derivative of histidine with a low affinity for Cu. Addition of free histidine prevented the formation of the LDL-Cu complexes and inhibited LDL oxidation, despite the fact that Cu remained redox-active. Interestingly, histidine was more effective than AA or DHA at limiting Cu binding to LDL, but at low concentrations AA and DHA were more effective than histidine at inhibiting LDL oxidation. These data suggest that there are at least two types of Cu binding sites on LDL: those that bind Cu in a redox-active form critical for initiation of LDL oxidation, and those that bind Cu in a redox-inactive form not contributing to LDL oxidation. The former sites may be primarily histidine residues of apolipoprotein B-100 that are oxidized to 2-oxo-histidine in the presence of Cu and AA or DHA, thus explaining, at least in part, the unusual inhibitory effect of vitamin C on Cu-induced LDL oxidation.
Lower prostate cancer risk in men with elevated plasma lycopene levels: results of a prospective analysis.
Gann PH; Ma J; Giovannucci E; Willett W; Sacks FM; Hennekens CH; Stampfer MJ
Department of Preventive Medicine, Northwestern University Medical School, Chicago, Illinois 60611, USA
Cancer Res (United States) Mar 15 1999, 59 (6) p1225-30
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.
NSAIDs and butyrate sensitize a human colorectal cancer cell line to TNF-alpha and Fas ligation: the role of reactive oxygen species.
Giardina C; Boulares H; Inan MS
Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269-3125, USA
Biochim Biophys Acta (Netherlands) Jan 11 1999, 1448 (3) p425-38
The nonsteroidal antiinflammatory drugs (NSAIDs) indomethacin and salicylic acid and the short chain fatty acid butyrate are effective colon cancer chemopreventive agents that increase reactive oxygen species (ROS) generation in colon cancer cells. Here we demonstrate that these agents sensitize the normally resistant human HT-29 colon cancer cell line to apoptosis induced by TNF-alpha or a Fas ligating antibody. The role of ROS in this sensitization is supported by the finding that direct exposure of the cells to H2O2 is sufficient for sensitization. Neither TNF-alpha nor Fas ligation alter basal or chemopreventive agent-activated ROS generation, suggesting that the death ligands and chemopreventive agents act in a complementary fashion. The dual chemopreventive agent/death ligand treatments do not increase Fas, TNF receptor 1, Bak or c-myc expression (although salicylic acid moderately induces of Fas expression). Cell death does correlate with alterations in NF-kappa B activity: the NSAIDs, butyrate and H2O2 enhance c-Rel complex formation by TNF-alpha and provide an overall enhancement of NF-kappa B activation by Fas. The antioxidant N-acetylcysteine (NAC) blocks cell death and NF-kappa B activation induced by Fas ligation, suggesting a potential role for NF-kappa B in Fas-induced apoptosis in these cells. The effects of NAC on TNF-alpha-induced cell death are more complex, with NAC being marginally protective and itself enhancing the formation of c-Rel containing complexes at higher concentrations (25 mM). The influence of NSAIDs and butyrate on ROS generation and death ligand sensitivity may be relevant to their ability to suppress colon carcinogenesis.
Manganese superoxide dismutase (MnSOD) genetic polymorphisms, dietary antioxidants, and risk of breast cancer.
Ambrosone CB; Freudenheim JL; Thompson PA; Bowman E; Vena JE; Marshall JR ; Graham S; Laughlin R; Nemoto T; Shields PG
Division of Molecular Epidemiology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
Cancer Res 1999 Feb 1;59(3):602-6
Oxidative stress, resulting from the imbalance between prooxidant and antioxidant states, damages DNA, proteins, cell membranes, and mitochondria and seems to play a role in human breast carcinogenesis. Dietary sources of antioxidants (chemical) and endogenous antioxidants (enzymatic), including the polymorphic manganese superoxide dismutase (MnSOD), can act to reduce the load of oxidative stress. We hypothesized that the valine-to-alanine substitution that seems to alter transport of the enzyme into the mitochondrion, changing its efficacy in fighting oxidative stress, was associated with breast cancer risk and that a diet rich in sources of antioxidants could ameliorate the effects on risk. Data were collected in a case-control study of diet and breast cancer in western New York from 1986 to 1991. Caucasian women with incident, primary, histologically confirmed breast cancer were frequency-matched on age and county of residence to community controls. Blood specimens were collected and processed from a subset of participants in the study (266 cases and 295 controls). Using a RFLP that distinguishes a valine (V) to alanine (A) change in the -9 position in the signal sequence of the protein for MnSOD, we characterized MnSOD genotypes in relation to breast cancer risk. We also evaluated the effect of the polymorphism on risk among low and high consumers of fruits and vegetables. Premenopausal women who were homozygous for the A allele had a 4-fold increase in breast cancer risk in comparison to those with 1 or 2 V alleles (odds ratio, 4.3; 95% confidence interval, 1.7-10.8). Risk was most pronounced among women below the median consumption of fruits and vegetables and of dietary ascorbic acid and alpha-tocopherol, with little increased risk for those with diets rich in these foods. Relationships were weaker among postmenopausal women, although the MnSOD AA genotype was associated with an almost 2-fold increase in risk (odds ratio, 1.8; confidence interval, 0.9-3.6). No appreciable modification of risk by diet was detected for these older women. These data support the hypothesis that MnSOD and oxidative stress play a significant role in breast cancer risk, particularly in premenopausal women. The finding that risk was greatest among women who consumed lower amounts of dietary antioxidants and was minimal among high consumers indicates that a diet rich in sources of antioxidants may minimize the deleterious effects of the MnSOD polymorphism, thereby supporting public health recommendations for the consumption of diets rich in fruits and vegetables as a preventive measure against cancer.
Docosahexaenoic acid is an antihypertensive nutrient that affects aldosterone production in SHR.
Engler MM; Engler MB; Goodfriend TL; Ball DL; Yu Z; Su P; Kroetz DL
Laboratory of Cardiovascular Physiology, Department of Physiological Nursing, University of California-San Francisco, California 94143-0610, USA. marguerite
Proc Soc Exp Biol Med (United States) May 1999, 221 (1) p32-8
The effects of dietary docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid, on blood pressure and some pressure-regulating systems were measured in young spontaneously hypertensive rats (SHR). Plasma aldosterone and corticosterone levels, adrenal aldosterone production in vitro, and characteristics of adrenal angiotensin receptors were measured after 6 weeks of diet. Renal cytochrome P450 (CYP) 4A gene expression and arachidonic acid metabolism by renal microsomes were also investigated. Plasma cholesterol, triglycerides, and high-density lipoprotein cholesterol were measured. Diets contained either corn/soybean oil alone (CSO), or oil enriched with DHA. After 6 weeks, rats fed DHA had systolic blood pressures averaging 34 mmHg less than controls (P < 0.001). Plasma aldosterone levels were 33% lower in the DHA-fed animals than in controls (22 +/- 3 vs. 33 +/- 3.7 ng/dl, P < 0.05). Plasma levels of corticosterone were 18% lower in animals fed DHA than in controls, but this difference was not statistically significant. Adrenal glomerulosa cells from DHA-fed rats produced less aldosterone in vitro in response to angiotensin II, ACTH, or potassium. The difference was less marked when aldosterone production was stimulated by supplying exogenous corticosterone, suggesting an effect of DHA on postreceptor steps in signal transduction or the early pathway of aldosteronogenesis. We found no significant differences in angiotensin receptor subtype, number, or affinity. Production of arachidonic epoxides by renal microsomes was 17% lower in DHA-fed animals than in controls (P < 0.05). Renal cortical mRNA levels of CYP4A genes and formation of 19- and 20-hydroxyeicosatetraenoic acid (HETE) did not differ between dietary groups. Plasma total cholesterol and high-density-lipoprotein (HDL) levels were significantly reduced in SHR fed the DHA supplement, but triglyceride levels were not significantly different. The effects of DHA on steroid and eicosanoid metabolism may be part of the mechanism by which this fatty acid prevents some of the hypertension in growing SHR.
Prevention of sudden cardiac death by dietary pure omega-3 polyunsaturated fatty acids in dogs.
Billman GE; Kang JX; Leaf A
Department of Physiology, The Ohio State University, Columbus, Ohio, USA.
Circulation (United States) May 11 1999, 99 (18) p2452-7
BACKGROUND: Rat diets high in fish oil have been shown to be protective against ischemia-induced fatal ventricular arrhythmias. Increasing evidence suggests that this may also apply to humans. To confirm the evidence in animals, we tested a concentrate of the free fish-oil fatty acids and found them to be antiarrhythmic. In this study, we tested the pure free fatty acids of the 2 major dietary omega-3 polyunsaturated fatty acids in fish oil: cis-5,8,11,14, 17-eicosapentaenoic acid (C20:5omega-3) and cis-4,7,10,13,16, 19-docosahexaenoic acid (C22:6omega-3), and the parent omega-3 fatty acid in some vegetable oils, cis-9,12,15-alpha-linolenic acid (C18:3omega-3), administered intravenously on albumin or a phospholipid emulsion.
METHODS AND RESULTS: The tests were performed in a dog model of cardiac sudden death. Dogs were prepared with a large anterior wall myocardial infarction produced surgically and an inflatable cuff placed around the left circumflex coronary artery. With the dogs running on a treadmill 1 month after the surgery, occlusion of the left circumflex artery regularly produced ventricular fibrillation in the control tests done 1 week before and after the test, with the omega-3 fatty acids administered intravenously as their pure free fatty acid. With infusion of the eicosapentaenoic acid, 5 of 7 dogs were protected from fatal ventricular arrhythmias (P<0.02). With docosahexaenoic acid, 6 of 8 dogs were protected, and with alpha-linolenic acid, 6 of 8 dogs were also protected (P<0.004 for each). The before and after control studies performed on the same animal all resulted in fatal ventricular arrhythmias, from which they were defibrillated.
CONCLUSIONS: These results indicate that purified omega-3 fatty acids can prevent ischemia-induced ventricular fibrillation in this dog model of sudden cardiac death.
Dietary n-3 PUFA increases the apoptotic response to 1,2-dimethylhydrazine, reduces mitosis and suppresses the induction of carcinogenesis in the rat colon.
Latham P; Lund EK; Johnson IT
Institute of Food Research-Norwich Laboratory, Norwich Research Park, Colney, UK.
Carcinogenesis 1999 Apr;20(4):645-50
The effect of dietary fish oil on colonic crypt cell apoptosis and proliferation was examined in male Wistar rats, 24 and 48 h after administration of 1,2-dimethylhydrazine (DMH), and its influence on the induction of aberrant crypt foci (ACF) in the distal colon was assessed. Rats (125-150 g) fed a high-fat semi-synthetic diet containing corn oil (CO) were given DMH (30 mg/kg body wt) or a sham injection of EDTA/NaCl. Animals were then fed either the CO diet or a diet in which fish oil (EPA 18.7%; DHA 8%) was substituted for corn oil. Subgroups of rats (n = 5) were killed after 24 and 48 h, and crypt cell apoptosis and proliferation were quantified by morphological criteria in isolated intact crypts from the mid and distal colon. Consumption of the fish oil diet (FO) was associated with increased apoptotic cell death (P < 0.001) and suppression of proliferation (P < 0.05) in colonic crypts both 24 and 48 h after DMH. In a second experiment, animals were given three injections of DMH or sham injections of carrier at weekly intervals. For 48 h after each injection animals were fed either the CO or FO diet, but otherwise maintained on the CO throughout. The number and crypt multiplicity of ACF in the distal colon were determined after 18 weeks, and animals given the FO diet for the 48 h period following carcinogen administration were found to have significantly fewer ACF than rats fed the CO diet (P < 0.05). The data demonstrate that the fatty acid composition of the diet is an important determinant in the induction of carcinogenesis by DMH. The proliferative and apoptotic response of the colonic crypt to carcinogen and fish oil, coupled with the reduced incidence of ACF, suggest n-3 PUFA can protect against the carcinogenic effects of DMH by mediating changes in the balance proliferation and cell death.
Prof. J.C. Beani, Service de Dermatologie, Hopital A.-Michallon, BP 217 X, 38043 Grenoble Cedex France
Revue Francaise d'Allergologie et d'Immunologie Clinique (France) 1999, 39/4 (311-323)
Most of the effects of the sun, particularly ultraviolet rays (UV), on the skin are harmful. Recent studies have clearly shown that UVA could be just as damaging as UVB via an indirect mechanism involving generation of oxygen-derived free radicals (OFR). Artificial photoprotection is designed to complete and palliate the deficiencies of natural photoprotection, either by passively preventing penetration of radiation to vital cell targets (clothing, sunscreens) or by blocking overproduction OFRs or by reinforcing or inducing an endogenous photoprotective mechanism. Artificial photoprotection has been largely based on sunscreens. Although these products are very effective against sunburn, their protection against the other effects of the sun is less apparent and must be clearly established. Moreover, they are not completely harmless, as they may induce cutaneous intolerance with long-term use. They are also expensive and fairly fastidious to apply for everyday use, which partly explains their poor use, which can limit their efficacy. Oral administration of free radical scavengers constitutes an attractive alternative. Unfortunately, the hopes raised by in vitro and animal studies have not yet been confirmed in man, due to the incomplete knowledge of anti-free radical defence and kinetic adapted to the redox potential of the cell. New studies should open up new horizons. The best photoprotection at the present time therefore remains avoidance of the sun and photoprotective clothing.
Effect of saturated, omega-3 and omega-6 polyunsaturated fatty acids on myocardial infarction
Nageswari K.; Banerjee R.; Menon V.P.
Dr. K. Nageswari, School of Biomedical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400 076 India
Journal of Nutritional Biochemistry (United States) 1999, 10/6 (338-344)
Dietary fatty acids have cholesterol lowering, antiatherogenic, and antiarrhythmic properties that decrease the risk of myocardial infarction (MI). This study was designed to study the effects of various oils rich in either polyunsaturated (omega-3 or omega-6) fatty acids (PUFA) or saturated fatty acids (SFA) on the severity of experimentally induced MI. Male albino Sprague-Dawley rats (100-150 g; n = 20) were fed diets enriched with fish oil (omega-3 PUFA), peanut oil (omega-6 PUFA), or coconut oil (SFA) for 60 days. Experimental MI was induced with isoproterenol. Mortality rates; serum enzymes aspartate amino transferase; alanine amino transferase; creatine phosphokinase (CPK); lipid profiles in serum, myocardium, and aorta; peroxide levels in heart and aorta; activities of catalase and superoxide dismutase; and levels of glutathione were measured. The results demonstrated that mortality rate, CPK levels, myocardial lipid peroxides, and glutathione levels were decreased in the omega-3 PUFA treated group. Maximum increase in parameters indicative of myocardial damage was seen in the coconut oil group. These findings suggest that dietary omega-3 PUFA offers maximum protection in experimentally induced MI in comparison to omega-6 PUFA and SFA enriched diets. SFA was found to have the least protective effect. Copyright (C) 1999 Elsevier Science Inc.
Serotonin-induced endothelial cell proliferation is blocked by omega-3 fatty acids
Pakala R.; Pakala R.; Radcliffe J.D.; Benedict C.R.
R. Pakala, Department of Internal Medicine, Division of Cardiology, University Texas Houston Med. School, 6431 Fannin, Houston, TX 77030 United States
Prostaglandins Leukotrienes and Essential Fatty Acids (United Kingdom) 1999, 60/2 (115-123)
Serotonin (5HT) released from aggregating platelets at sites of vascular injury is a known mitogen for vascular endothelial cells. Recent studies have indicated that regenerating endothelial cells at sites of vessel wall injury may play a role in the development of restenosis by synthesizing and releasing growth factors for vascular smooth muscle cells, proliferation of which may result in the development of neointima. Diets rich in fish oils (omega-3 fatty acids) are associated with reduced risk of cardiovascular disease including atherosclerosis and restenosis. This study examined the effect of the omega-3 and other fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on 5HT induced endothelial cell proliferation. Among the fatty acids examined only EPA and DHA could reverse the mitogenic effect of 5HT on vascular endothelial cells, whereas oleic acid or palmitic acid did not have any effect. When added together, EPA and DHA potentiate each other in reversing the mitogenic effect of 5HT. EPA and DHA also inhibited the 5HT-induced increase in the 5HT, receptor mRNA, without a change in the receptor density or affinity. This data suggests that one of the mechanisms by which omega-3 fatty acids may attenuate the development of atherosclerosis or restenosis is to inhibit the mitogen induced growth of vascular endothelial cells, which attenuates the release of growth factors for vascular smooth muscle cells.
Effects of eicosapentaenoic acid on the contraction of intact, and spontaneous contraction of chemically permeabilized mammalian ventricular myocytes
Rodrigo G.C.; Dhanapala S.; Macknight A.D.C.
G.C. Rodrigo, Department of Physiology, Otago Medical School, University of Otago, Dunedin New Zealand
Journal of Molecular and Cellular Cardiology (United Kingdom) 1999, 31/4 (733-743)
The n-3 polyunsaturated fatty acids appear to protect the heart from ischaemia-induced arrhythmias. We have used single adult guinea-pig and rat ventricular myocytes to investigate the effects of the n-3 polyunsaturated fatty acid eicosapentaenoic acid on, (i) the L-type Casup 2sup + current, (ii) twitch contraction, and (iii) the spontaneous mechanical activity induced in chemically skinned myocytes by an elevation of the superfusing [Casup 2sup +]. Eicosapentaenoic acid reduced the size of the L-type Casup 2sup + current in a dose-dependent manner in myocytes from both species. Inclusion of delipidated bovine serum albumin (BSA) to the Tyrode, which binds eicosapentaenoic acid, completely reversed the inhibition of the Casup 2sup + current in both guinea-pig and rat cells. The effects of eicosapentaenoic acid on contraction were species dependent. In guinea-pig myocytes it produced a reduction in contraction size which was complex, being described by three phases. In rat cells there was an initial increase in the size of contractions, followed by a simple reduction in contraction strength. Delipidated BSA completely reversed these effects in rat cells but only partially restored twitch contraction in guinea-pig cells (60%). In saponin permeabilized cells, the frequency of the spontaneous activity evoked by elevation of [Casup 2sup +] was reduced by micromolar concentrations of eicosapentaenoic acid in cells from both species. The reduction in the amplitude of contractions caused by eicosapentaenoic acid can be explained by an inhibition of the L-type Casup 2sup + current, and by a reduction in Casup 2sup + released from the sarcoplasmic reticulum (SR). The inhibition of the release of Casup 2sup + from the SR reduces the frequency of [Casup 2sup +] dependent spontaneous contractions in chemically skinned guinea-pig and rat ventricular myocytes.
Omega-3 fatty acids in adipose tissue and risk of myocardial infarction: The EURAMIC study
Guallar E.; Aro A.; Jimenez F.J.; Martin-Moreno J.M.; Salminen I.; Van't Veer P.; Kardinaal A.F.M.; Gomez-Aracena J.; Martin B.C.; Kohlmeier L.; Kark J.D.; Mazaev V.P.; Ringstad J.; Guillen J.; Riemersma R.A.; Huttunen J.K.; Thamm M.; Kok F.J.
E. Guallar, Depto. de Epidemiol./Bioestadistica, Escuela Nacional de Sanidad, Instituto de Salud Carlos III, Sinesio Delgado 8, 28029 Madrid Spain
Arteriosclerosis, Thrombosis, and Vascular Biology (United States) 1999, 19/4 (1111-1118)
Omega-3 fatty acids have potential antiatherogenic, antithrombotic, and antiarrhythmic properties, but their role in coronary heart disease remains controversial. To evaluate the association of omega-3 fatty acids in adipose tissue with the risk of myocardial infarction in men, a case-control study was conducted in eight European countries and Israel. Cases (n=639) included patients with a first myocardial infarction admitted to coronary care units within 24 hours from the onset of symptoms. Controls (n=700) were selected to represent the populations originating the cases. Adipose tissue levels of fatty acids were determined by capillary gas chromatography. The mean (+/-SD) proportion of alpha-linolenic acid was 0.77% (+/-0.19) of fatty acids in cases and 0.80% (+/-0.19) of fatty acids in controls (P=0.01). The relative risk for the highest quintile of alpha-linolenic acid compared with the lowest was 0.42 (95% confidence interval [CI] 0.22 to 0.81, P-trend=0.02). After adjusting for classical risk factors, the relative risk for the highest quintile was 0.68 (95% CI 0.31 to 1.49, P-trend=0.38). The mean proportion of docosahexaenoic acid was 0.24% (+/-0.13) of fatty acids in cases and 0.25% (+/-0.13) of fatty acids in controls (P=0.14), with no evidence of association with risk of myocardial infarction. In this large case-control study we could not detect a protective effect of docosahexaenoic acid on the risk of myocardial infarction. The protective effect of alpha-linolenic acid was attenuated after adjusting for classical risk factors (mainly smoking), but it deserves further research.
Procoagulant activity and cytokine expression in whole blood cultures from patients with atherosclerosis supplemented with omega-3 fatty acids
Seljeflot I.; Johansen O.; Arnesen H.; Eggesbo J.-B.; Westvik A.-B.; Kierulf P.
Dr. I. Seljeflot, Department of Medicine, Ulleval University Hospital, N-0407 Oslo Norway
Thrombosis and Haemostasis (Germany) 1999, 81/4 (566-570)
Omega-3 fatty acids (n-3 FA) may reduce atherogenesis and thrombosis. We investigated the effects of n-3 FAs on procoagulant activity and cytokine expression in whole blood cultures from patients with atherosclerosis. Eleven of the 23 included patients had received 5.1 g n-3 FA daily for 6 months (group I) whereas 12 patients had been on placebo (group II). All patients were then given 5.1 g n-3 FA daily for another 4 weeks. At baseline significantly lower levels of LPS-induced prothrombin fragmentinf 1inf +inf 2 were found in group I (p = 0.010), this difference being eliminated after 4 weeks. Il-6 and TNF(alpha) were significantly higher at baseline in group I and the differences in changes from baseline between the groups were statistically highly significant with increasing values in group II (Il-6 p = 0.001, TNF(alpha) p = 0.002). The present results indicate a reduction in pro-thrombotic potential in patients receiving highly concentrated n-3 FA, whereas some proinflammatory responses might be adverse.
Antithrombotic effects of (n-3) polyunsaturated fatty acids in rat models of arterial and venous thrombosis
Andriamampandry M.D.; Leray C.; Freund M.; Cazenave J.-P.; Gachet C.
C. Leray, INSERM U311, Etab. Transfus. Sanguine Strasbourg, 10 rue Spielmann, 67065 Strasbourg Cedex France
Thrombosis Research (United Kingdom) 01 JAN 1999, 93/1 (9-16)
The antithrombotic effects of dietary lipids were investigated in rat models of arterial and venous thrombosis. In the arterial model, thrombus formation was evaluated by determination of the occlusion time and the deposition of sup 1sup 1sup 1In-labeled platelets and 125-labeled fibrinogen in a collagen-coated glass capillary inserted into an arterio-arterial shunt. Venous thrombosis was evaluated by measurement of the thrombus weight after administration of thromboplastin as a source of tissue factor and establishment of stasis in the vena cava. Diets were supplemented with saturated (SAT group) or (n-3) fatty acids, the latter being added either as MaxEPA(R) oil (MaxEPA group), or as docosahexaenoic (DHA group) or eicosapentaenoic (EPA group) ethyl ester. Only the MaxEPA group displayed a prolonged occlusion time as compared with all other groups. Platelet accumulation, similar in the MaxEPA, EPA and DHA groups (13.3, 16,7 and 17.7 x 10sup 6 platelets/shunt, respectively), was significantly higher in the SAT group (25.3x10sup 6 platelets/shunt), while accumulation of fibrinogen-fibrin was similar whatever the group. There was a trend towards a lower venous thrombus weight in MaxEPA fed rats relative to those fed other diets. Our data indicate that the MaxEPA diet had antithrombotic effects in arterial and to a lesser extent venous thrombosis models, best attributed to its multiple targeting of platelets and coagulation.
PUFA and aging modulate cardiac mitochondrial membrane lipid composition and Casup 2sup + activation of PDH
Pepe S.; Tsuchiya N.; Lakatta E.G.; Hansford R.G.
S. Pepe, Cardiac Surg. Res./Transplant. Unit, Baker Medical Research Institute, Commercial Road, Melbourne, Vic. 3181 Australia
American Journal of Physiology - Heart and Circulatory Physiology (United States) 1999, 276/1 45-1 (H149-H158)
Aberrations in cell Casup 2sup + homeostasis have been known to parallel both changes in membrane lipid composition and aging. Previous work has shown that the lowered efficiency of work performance, which occurs in isolated hearts from rats fed a diet rich in n-6 polyunsaturated fatty acids (PUFA), relative to those fed n-3 PUFA, could be raised by mitochondrial (Mito) Casup 2sup + transport inhibition. We tested whether, after Casup 2sup +-dependent stress, the Casup 2sup +-dependent activation of pyruvate dehydrogenase (PDH(A)/PDH(Total)) and Mito Casup 2sup + cycling could be manipulated by varying the ratio of n-3 to n-6 PUFA in Mito membranes in young (6 mo) and aged (24 mo) isolated rat hearts treated to n-3 or n-6 PUFA-rich diet. Inotropic stimulation by 1 muM norepinephrine (NE) of 24-mo n-6 PUFA-rich hearts elevated total Mito Casup 2sup + content 38% more than in 6-mo hearts (P < 0.05). However, both the NE- induced rise in Mito Casup 2sup + and the difference in response between 6- and 24- mo hearts were partially abolished by n-3 PUFA treatment. NE increased the fractional activation of PDH by 44% above control levels in the 6-mo group compared with 49% in the 24-mo group after n-6 PUFA diet. However, NE stimulation of PDHA was attenuated by n-3 PUFA diet, attaining values only 29 and 23% above control levels in 6- and 24-mo mitochondria, respectively (P < 0.05). Global ischemia and reperfusion (I/R) in n-6 PUFA hearts gave rise to higher levels of total Mito Casup 2sup + concentration (P < 0.0001) and PDHA (P < 0.0001) compared with n-3 PUFA. Ruthenium red (3.4 muM) abolished the effects of I/R in all groups. With aging, heart Mito membrane phosphatidylcholine was increased after n-6 PUFA-rich diet (by -15%, P < 0.05), whereas cardiolipin and n-3 PUFA content were diminished by 31% (P < 0.05) and 73% (P < 0.05), respectively. These effects were prevented by n-3 PUFA-rich diet. The present study, by directly manipulating the cardiac Mito membrane n-3-to-n-6 PUFA ratio, shows that the activation of Casup 2sup +-dependent PDH can be augmented when the n-3-to-n-6 PUFA ratio is low (n-6 PUFA-rich diet; 24-mo hearts) or attenuated when this ratio is relatively high (n-3 PUFA-rich diet). We propose that one of the consequences of dietary-induced manipulation of membrane phospholipids and PUFAs may be the altered flux of Casup 2sup + across the Mito membrane and thus altered intramitochondrial Casup 2sup +-dependent processes.
Possibilities of fish oil application for food products enrichment with omega-3 PUFA
Kolanowski W.; Swiderski F.; Berger S.
W. Kolanowski, Warsaw Agricultural University-SGGW, Fac. Human Nutrition Home Economics, ul. Nowoursynowska 166, 02-787 Warsaw Poland
International Journal of Food Sciences and Nutrition (United Kingdom) 1999, 50/1 (39-49)
Polyunsaturated fatty acids of omega-3 series (omega-3 or n-3 PUFA), especially long chain EPA and DHA, exert strong positive influence on human health. Intake of these fatty acids is however usually too low: that brings many unfavourable health effects to the whole populations. Therefore the increased consumption of omega-3 fatty acids is recommended. A good way to raise the omega-3 PUFA content in the diet, without radical changes of eating habits, seems to be the enrichment of frequent and common consumed food products. The target of this study was to explore the possibility of selected food products enrichment with omega-3 PUFA, using fish oil preparations in liquid (30% EPA and DHA) and powder-micro-encapsulated (10%) form, without significant taste deterioration of the enriched foods. These were designed as functional food, useful in prevention of many diseases. It was shown that food product palatability was affected very differently by enrichment. The highest inclusion level was obtained in the case of instant powder-milk-based formulae concentrates (up to 18% that provided 1.8% EPA, DHA), fats (up to 1.5% that provided 0.5% EPA, DHA), and products of high sweetness and flavours intensity, that mask unpleasant fishy taste and odour. Enriched salad oil retained good quality during 4 months of storage: also concentrates - during 6 months. Shelf-life prolongation of low pH, water-based products (fruit beverages), requires additional technological treatment to decrease oxidation. Enrichment at significant level (up than 0.1% that provides 0.03% EPA, DHA) of low-flavours intensity products (milk, vegetable juice), strongly decreases their palatability. As a final conclusion authors suggest that frequent consumption of food products enriched at sensory acceptable levels may considerably increase EPA and DHA amount in the diet, improving its nutritional quality.
Fish oil supplementation prevents diabetes-induced nerve conduction velocity and neuroanatomical changes in rats
Gerbi A.; Maixent J.-M.; Ansaldi J.-L.; Pierlovisi M.; Coste T.; Pelissier J.-F.; Vague P.; Raccah D.
A. Gerbi, Diabetology Department, CHU Timone, 13385 Marseille Cedex 5 France
Journal of Nutrition (United States) 1999, 129/1 (207-213)
Diabetic neuropathy has been associated with a decrease in nerve conduction velocity, Na,K-ATPase activity and characteristic histological damage of the sciatic nerve. The aim of this study was to evaluate the potential effect of a dietary supplementation with fish oil [(n-3) fatty acids] on the sciatic nerve of diabetic rats. Diabetes was induced by intravenous streptozotocin injection. Diabetic animals (n = 20) were fed a nonpurified diet supplemented with either olive oil (DO) or fish oil (DM), and control animals (n = 10) were fed a nonpurified diet supplemented with olive oil at a daily dose of 0.5 g/kg by gavage for 8 wk. Nerves were characterized by their conduction velocity, morphometric analysis and membrane Na,K-ATPase activity. Nerve conduction velocity, as well as Na,K- ATPase activity, was improved by fish oil treatment. A correlation was found between these two variables (R = 0.999, P < 0.05). Moreover, a preventive effect of fish oil was observed on nerve histological damage [endoneurial edema, axonal degeneration (by 10-15%) with demyelination]. Moreover, the normal bimodal distribution of the internal diameter of myelinated fibers was absent in the DO group and was restored in the DM group. These data suggest that fish oil therapy may be effective in the prevention of diabetic neuropathy.
Cardiovasoprotective foods and nutrients: possible importance of magnesium intake.
Durlach J; Bac P; Bara M; Guiet-Bara A
Hopital St. Vincent-de-Paul, Paris, France.
Magnes Res (England) Mar 1999, 12 (1) p57-61
Various highly efficient cardiovasoprotective diets associate reduced intake of total and saturated fats, reasonable supply of monounsaturated fat and omega-3 fatty acids, moderate consumption of alcohol, increased intake of cereals, fruits, vegetables, fish and low fat dairy products. Among several protective nutrients magnesium should be given particular consideration because of the very frequent occurrence of chronic primary magnesium deficiency which appears to act as a cardiovascular risk factor and also reversely, because of the noticeable high level of the magnesium content in cardiovasoprotective diets. (48 Refs.)
Stimulation of cell division in the rat by NaCl, KCl, MgCl2, and CaCl2, and inhibition of the sodium chloride effect on the glandular stomach by ascorbic acid and beta-carotene.
Lugli SM; Lutz WK
Institute of Toxicology, Swiss Federal Institute of Technology and University of Zurich, Schwerzenbach.
J Cancer Res Clin Oncol (Germany) 1999, 125 (3-4) p209-13
Three questions associated with the stimulation of cell division by chloride salts have been investigated: (i) whether cations other than sodium show a similar effect, (ii) whether vitamins can have a preventive activity, and (iii) whether subchronic treatment with sodium chloride in the diet is also effective. Male Fischer 344 rats were given solutions of the chloride salts of sodium, potassium, magnesium, and calcium by oral gavage. Water was used for control. After 4 h, a 24-h osmotic minipump containing 5-bromo-2'-deoxyuridine was implanted subcutaneously. The forestomach and glandular stomach, as well as liver and bladder were analyzed immunohistochemically 24 h later for the proportion of cells in S phase as an indicator of the rate of replicative DNA synthesis. For both the forestomach and the glandular stomach, potassium was as potent as sodium, and the divalent cations Mg and Ca were even more potent on a molar basis. Supplementation of the diet with ascorbic acid (2 g/kg food) or beta-carotene (12.5 mg/kg food) for 1 week before gavage of the sodium chloride solution resulted in an inhibition of the stimulation of cell division. A putative tumor-chemopreventive activity of the two vitamins might therefore not only rely on their antioxidative properties but may include effects on the cell cycle. A 4-week treatment with a sodium chloride supplement in the diet (2% and 4% supplement) resulted in a significant stimulation of cell division not only in both parts of the stomach and in the bladder (with the 4% supplement) but also in the liver (even with the 2% supplement). Sodium-chloride-stimulated cell turnover therefore is a sustained effect.
Lifestyle modifications to prevent and control hypertension. 1. Methods and an overview of the Canadian recommendations. Canadian Hypertension Society, Canadian Coalition for High Blood Pressure Prevention and Control, Laboratory Centre for Disease Control at Health Canada, Heart and Stroke Foundation of Canada.
Campbell NR; Burgess E; Choi BC; Taylor G; Wilson E; Cleroux J; Fodor JG; Leiter LA; Spence D
Division of General Internal Medicine, University of Calgary, Alta.
CMAJ (Canada) May 4 1999, 160 (9 Suppl) pS1-6
OBJECTIVE: To provide updated, evidence-based recommendations for health care professionals on lifestyle changes to prevent and control hypertension in otherwise healthy adults (except pregnant women).
OPTIONS: For people at risk for hypertension, there are a number of lifestyle options that may avert the condition--maintaining a healthy body weight, moderating consumption of alcohol, exercising, reducing sodium intake, altering intake of calcium, magnesium and potassium, and reducing stress. Following these options will maintain or reduce the risk of hypertension. For people who already have hypertension, the options for controlling the condition are lifestyle modification, antihypertensive medications or a combination of these options; with no treatment, these people remain at risk for the complications of hypertension.
OUTCOMES: The health outcomes considered were changes in blood pressure and in morbidity and mortality rates. Because of insufficient evidence, no economic outcomes were considered.
EVIDENCE: A MEDLINE search was conducted for the period January 1996 to September 1996 for each of the interventions studied. Reference lists were scanned, experts were polled, and the personal files of the authors were used to identify other studies. All relevant articles were reviewed, classified according to study design and graded according to level of evidence.
VALUES: A high value was placed on the avoidance of cardiovascular morbidity and premature death caused by untreated hypertension.
BENEFITS, HARMS AND COSTS: Lifestyle modification by means of weight loss (or maintenance of healthy body weight), regular exercise and low alcohol consumption will reduce the blood pressure of appropriately selected normotensive and hypertensive people. Sodium restriction and stress management will reduce the blood pressure of appropriately selected hypertensive patients. The side effects of these therapies are few, and the indirect benefits are well known. There are certainly costs associated with lifestyle modification, but they were not measured in the studies reviewed. Supplementing the diet with potassium, calcium and magnesium has not been associated with a clinically important reduction in blood pressure in people consuming a healthy diet.
RECOMMENDATIONS: (1) It is recommended that health care professionals determine the body mass index (weight in kilograms/[height in metres]2) and alcohol consumption of all adult patients and assess sodium consumption and stress levels in all hypertensive patients. (2) To reduce blood pressure in the population at large, it is recommended that Canadians attain and maintain a healthy body mass index. For those who choose to drink alcohol intake should be limited to 2 or fewer standard drinks per day (maximum of 14/week for men and 9/week for women). Adults should exercise regularly. (3) To reduce blood pressure in hypertensive patients, individualized therapy is recommended. This therapy should emphasize weight loss for overweight patients, abstinence from or moderation in alcohol intake, regular exercise, restriction of sodium intake and, in appropriate circumstances, individualized cognitive behaviour modification to reduce the negative effects of stress.
VALIDATION: The recommendations were reviewed by all of the sponsoring organizations and by participants in a satellite symposium of the fourth international Conference on Preventive Cardiology. They are similar to those of the World Hypertension League and the Joint National committee, with the exception of the recommendations on stress management, which are based on new information. They have not been clinically tested. SPONSORS: The Canadian Hypertension Society, the Canadian Coalition for High Blood Pressure Prevention and Control, the Laboratory Centre for Disease Control at health Canada, and the Heart and Stroke Foundation of Canada.
Prevention of eclampsia.
Belfort MA; Anthony J; Saade GR
Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City, USA.
Semin Perinatol (United States) Feb 1999, 23 (1) p65-78
Eclampsia continues to be a major cause of maternal morbidity and mortality rates, especially in underdeveloped nations. Our data indicate that eclampsia may represent the end stage of at least two very different pathophysiological pathways: one in which cerebral perfusion is low because of vasospasm and another in which cerebral perfusion is increased because of abnormal autoregulation and a failure of the normal protective mechanisms. Magnesium sulfate has been extensively used in the management and prevention of eclamptic seizures in the United States and has been recently shown to be superior to both diphenylhydantoin and diazepam. We have shown that magnesium sulfate is a potent vasorelaxant and that its action may depend on improving cerebral perfusion. Nimodipine, a calcium channel blocker with selective cerebrovascular effect, is currently under investigation in severe preeclampsia. The data show that it is as effective as magnesium sulfate in preventing eclampsia, with less maternal and fetal side effects. Magnesium sulfate and nimodipine have opposite effects on the estimated cerebral perfusion pressure as determined with the Doppler ultrasound. We speculate that the estimated cerebral perfusion pressure may be used to determine the type of cerebrovascular abnormality and the most appropriate treatment in each individual patient with preeclampsia. (87 Refs.)
Coronary microvascular protection with mg2+: effects on intracellular calcium regulation and vascular function.
Matsuda N; Tofukuji M; Morgan KG; Sellke FW
Division of Cardiothoracic Surgery, Department of Surgery of Beth Israel Deaconess Medical Center and Harvard Medical School, Boston 02215, Massachusetts, USA.
Am J Physiol (United States) Apr 1999, 276 (4 Pt 2) pH1124-30
The use of Mg2+-supplemented hyperkalemic cardioplegia preserves microvascular function. However, the mechanism of this beneficial action remains to be elucidated. We investigated the effects of Mg2+ supplementation on the regulation of intracellular calcium concentration ([Ca2+]i) and vascular function using an in vitro microvascular model. Ferret coronary arterioles (80-150 micrometer in diameter) were studied in a pressurized (40 mmHg) no-flow, normothermic (37 degrees C) state. Simultaneous monitoring of internal luminal diameter and [Ca2+]i using fura 2 were made with microscopic image analysis. The microvessels (n = 6 each group) were divided into four groups according to the content of MgCl2 (nominally 0, 1.2, 5.0, and 25.0 mM) in a hyperkalemic cardioplegic solution ([K+] 25.0 mM). After baseline measurements, vessels were subjected to 60 min of hypoxia with hyperkalemic cardioplegia (equilibrated with 95% N2-5% CO2) containing each concentration of Mg2+ ([Mg2+]) and were then reoxygenated. During hyperkalemic cardioplegia, [Ca2+]i increased in a time-dependent manner in all groups. In the lower [Mg2+] cardioplegia groups, [Ca2+]i was significantly increased at the end of the 60-min cardioplegic period (247 +/- 44 nM and 236 +/- 49 nM in [Mg2+] 0 and 1.2 mM groups, respectively; both P < 0.05 vs. baseline) with 19.6-17.2% vascular contraction. Conversely, there was no significant [Ca2+]i increase in the higher [Mg2+] cardioplegia groups and less vascular contraction (5.4-4.1%, both P < 0.05 vs. [Mg2+] 1.2 mM group). After reperfusion, agonist (U-46619, thromboxane A2 analog)-induced vascular contraction was significantly enhanced in the lower [Mg2+] cardioplegia groups (both P < 0.05 vs. control) but was normalized in the higher [Mg2+] cardioplegia groups. Intrinsic myogenic contraction was significantly decreased in the lower [Mg2+] cardioplegia groups (both P < 0.05 vs. control) but was preserved in the higher [Mg2+] cardioplegia groups. These results suggest that supplementation of the solution with >5.0 mM [Mg2+] may prevent hyperkalemic cardioplegia-related intracellular Ca2+ overloading and preserve vascular contractile function in coronary microvessels.
Thromboxane Ainf 2 fails to induce proliferation of smooth muscle cells enriched with eicosapentaenoic acid and docosahexaenoic acid
Pakala R.; Pakala R.; Benedict C.R.
R. Pakala, Department of Internal Medicine, Division of Cardiology, University Texas HSC Medical School, 6431 Fannin, Houston, TX 77030 United States
Prostaglandins Leukotrienes and Essential Fatty Acids (United Kingdom) 1999, 60/4 (275-281)
Thromboxane Ainf 2 (TXAinf 2) released from aggregating platelets and injured vessel wall stimulates smooth muscle cell proliferation, which may contribute to the development of vascular lesion formation after percutaneous transluminal coronary angioplasty. Polyunsaturated fatty acids (n-3) present in the fish oils have been shown to have anti-atherosclerotic effects. In view of this, we examined the effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the active ingredients of fish oils on TXAinf 2 induced smooth muscle cell proliferation. To find out the specificity of these fatty acids we used gamma-linolenic acid (n-6) and oleic acid (n-9) as controls. It was found that TXAinf 2 failed to stimulate proliferation of smooth muscle cells preloaded with EPA or DHA but not with gamma-linolenic acid or oleic acid. Further, when smooth muscle cells were preloaded with both EPA and DHA, they acted together in preventing the TXAinf 2 induced smooth muscle cell proliferation. These results demonstrate that one of the mechanisms by which fish oils may prevent neointima formation is by making smooth muscle cells less responsive to TXAinf 2 induced proliferation of smooth muscle cells.
Fish oil-enriched nutritional supplement attenuates progression of the acute-phase response in weight-losing patients with advanced pancreatic cancer
Barber M.D.; Ross J.A.; Preston T.; Shenkin A.; Fearon K.C.H.
K.C.H. Fearon, University Department of Surgery, Royal Infirmary of Edinburgh, Edinburgh EH3 9YW United Kingdom
Journal of Nutrition (United States) 1999, 129/6 (1120-1125)
The presence of an acute-phase protein response (APPR) has been suggested to shorten survival and contribute to weight loss in patients with pancreatic cancer. Fatty acids derived from fish oil have been shown to alter proinflammatory cytokine production and acute-phase protein synthesis in vitro. The present study was designed to determine the effects of a fish oil- enriched nutritional supplement on the concentrations of a range of individual acute-phase proteins (APP) in patients with advanced pancreatic cancer. In a sequential series, 18 patients with pancreatic cancer received the supplement (providing 2 g eicosapentaenoic acid and 1 g docosahexaenoic acid/d) for 3 wk while another 18 received full supportive care alone. Six healthy subjects served as additional controls. Acute-phase proteins were measured before and after the 3-wk intervention period in cancer patients. At baseline, albumin, transferrin and pre-albumin were significantly reduced and fibrinogen, haptoglobin, alpha-1-acid glycoprotein, alpha-1-antitrypsin, ceruloplasmin and C-reactive protein (CRP) were significantly elevated in the cancer patients compared with healthy controls, reflecting their roles as negative and positive acute phase proteins, respectively. In the supplemented cancer group, the only significant change in APP concentrations over the 4- wk study period was an increase in transferrin. In the control cancer group there were further significant reductions in albumin, transferrin and pre- albumin, and a significant increase in CRP concentration. These results suggest that many positive and negative APP are altered in advanced pancreatic cancer. The APPR tends to progress in untreated patients but may be stabilized by the administration of a fish oil-enriched nutritional supplement. This may have implications for reducing wasting in such patients.
Choline deficiency-induced apoptosis in PC12 cells is associated with diminished membrane phosphatidylcholine and sphingomyelin, accumulation of ceramide and diacylglycerol, and activation of a caspase.
Yen CL; Mar MH; Zeisel SH
Department of Nutrition, School of Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7400, USA.
FASEB J (United States) Jan 1999, 13 (1) p135-42
It is not well appreciated that nutritional status can modulate apoptosis, a process that eliminates unwanted or damaged cells. Choline is an essential nutrient, and its absence induces apoptosis. When PC12 cells were cultivated in a choline-free medium, apoptosis was induced (27.4% of cells apoptotic at 72 h as compared to 4.4% in control medium). In choline-free medium at 72 h, there was a 49% decrease in phosphatidylcholine concentration (P<0.01) and a 34% decrease in sphingomyelin concentration (P<0.01); however, there was no change in phosphatidylethanolamine concentration. Before detecting increased apoptosis in choline-deficient cells, we measured a significant increase in ceramide (218% control) and diacyglycerol (155% control) concentrations. The addition of a cell-permeable ceramide to cells in control medium induced apoptosis; however, adding a cell-permeable diacyglycerol did not induce apoptosis. Caspase is a common mediator of apoptosis, and choline deficiency-induced apoptosis was prevented completely by replacing choline or adding a caspase inhibitor into the medium within 48 h of initial choline deprivation. In those cells rescued by replacing choline at 36 h, the concentrations of phosphatidylcholine, sphingomyelin, ceramide, and diacyglycerol returned to levels of control cells. In those cells rescued by adding a caspase inhibitor at 36 h, the concentrations of sphingomyelin and ceramide returned to control levels, but the concentrations of phosphatidylcholine and diacyglycerol did not return to normal. We propose that availability of dietary factors (choline in this model) can modulate apoptosis. Mechanisms that we identify using this model may help us to explain why dietary choline influences brain development.
Functional relationship between age-related immunodeficiency and learning deterioration.
Zhang Y; Moriguchi T; Saito H; Nishiyama N
Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Japan.
Eur J Neurosci (France) Dec 1998, 10 (12) p3869-75
Disordered immune responses are supposed to alter the function of the central nervous system through the neuroendocrine immunomodulation network. In this paper, we studied the influence of the immune function on learning performances from the angle of pharmacology using aged garlic extract (AGE), an immunomodulator. Splenocyte proliferation, induced by concanavalin A or lipopolysaccharide, and the antibody production response were declined in senescence accelerated mouse-prone 8 (SAMP8) aged 12 months compared with age-matched SAMR1 (SAM-resistant 1). Chronic oral administration of AGE-containing food (2%, w/w) significantly enhanced the immune responses of both SAMP8 and SAMR1. Male ddY mice were thymectomized 4 weeks after birth and fed AGE-containing food after the operation until the experiments were finished. Learning performances, brain monoamine content and choline acetyltransferase (ChAT) activity, as well as the immune response were evaluated 10 months after the operation. Thymectomy resulted in not only immunodeficiency, but also deteriorated learning ability. AGE treatment prevented the reduction of the antibody production response induced by thymectomy and improved the thymectomy-induced deterioration of learning behaviours in passive avoidance performance and in a spatial memory task. The contents of hypothalamic noradrenaline, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and the hypothalamic ChAT activity were increased in thymectomized mice compared to those of sham-operated control, while AGE treatment restored them to the control levels. These results suggest that the improvement of immune function is closely related to the amelioration of age-associated deterioration of learning and memory.
Protection against developmental retardation in apolipoprotein E-deficient mice by a fatty neuropeptide: implications for early treatment of Alzheimer's disease.
Gozes I; Bachar M; Bardea A; Davidson A; Rubinraut S; Fridkin M; Giladi E
Department of Clinical Biochemistry, Sackler Medical School, Tel Aviv University, Israel.
J Neurobiol (United States) Sep 1997, 33 (3) p329-42
Stearyl-Nle17-VIP (SNV) is a novel agonist of vasoactive intestinal peptide (VIP) exhibiting a 100-fold greater potency than the parent molecule and specificity for a receptor associated with neuronal survival. Here, mice deficient in apolipoprotein E (ApoE), a molecule associated with the etiology of Alzheimer's disease, served as a model to investigate the developmental and protective effects of SNV. In comparison to control animals, the deficient mice exhibited (a) reduced amounts of VIP messenger RNA; (b) decreased cholinergic activity (c) significant retardation in the acquisition of developmental milestones: forelimb placing behavior and cliff avoidance behavior; and (d) learning and memory impairments. Daily injections of SNV to ApoE-deficient newborn pups resulted in increased cholinergic activity and marked improvements in the time of acquisition of behavioral milestones, with peptide-treated animals developing as fast as control animals and exhibiting improved cognitive functions after cessation of peptide treatment. Specificity was demonstrated in that treatment with a related peptide (PACAP), pituitary adenylate cyclase-activating peptide, produced only limited amelioration. As certain genotypes of ApoE increase the probability of Alzheimer's disease, early counseling and preventive treatments may now offer an important route for therapeutics design.
The influence of DHEA on serum lipids, insulin and sex hormone levels in rabbits with induced hypercholesterolemia.
Bednarek-Tupikowska G; Milewicz A; Kossowska B; Bohdanowicz-Pawlak A; Sciborski R
Department of Endocrinology, Medical Academy, Wroclaw, Poland.
Gynecol Endocrinol (England) Mar 1995, 9 (1) p23-8
The authors estimated the influence of dehydroepiandrosterone (DHEA) administration, a potential antiatherogenic agent, on serum lipids, sex hormones and insulin levels in male rabbits fed on an atherogenic diet. They concluded that (1) DHEA administration has an unfavorable impact on the serum lipid profile; (2) an atherogenic diet causes insulin resistance; (3) the glucose and insulin levels are not related to DHEA in normally fed rabbits and in rabbits with hyperlipoproteinemia; (4) an atherogenic diet causes a slight increase of estradiol concentration; (5) DHEA treatment has no significant effect on testosterone and estradiol concentrations in both normally fed rabbits and those on an atherogenic diet; (6) DHEA administration has an anti-obesity effect.
The effect of administration of estradiol and testosterone on body growth of young male rats.
Cikos S; Kuchar S; Koppel J
Institute of Animal Physiology, Slovak Academy of Sciences, Kosice.
Physiol Res (Czechoslovakia) 1992, 41 (5) p387-92
The influence of estradiol and testosterone on body growth of young male Wistar rats was investigated. In the first experiment, estradiol was given to intact ad libitum fed male rats at 32, 37 and 42 days of age. Moreover, two untreated groups of animals were used: one was fed restrictedly according to the food intake of animals receiving estradiol and another was fed ad libitum. The animals were sacrificed at 47 days of age. Both untreated groups of animals achieved significantly higher body weight and length of tibia than estradiol treated animals. Also the growth of the tail of untreated animals was more intensive than that of estradiol treated animals. In the second experiment, estradiol was given to intact ad libitum fed male rats at 30, 35 and 45 days of age. Moreover, testosterone was given to a half of these animals at 45, 50 and 55 days of age. The animals were sacrificed at 60 days of age. Administration of testosterone significantly increased the growth of the tail and tibia in comparison to the animals which did not receive testosterone after estradiol administration. The results of the present study show that the inhibitory effect of estradiol on body growth of young male rats is not only the result of decreased food intake and that testosterone can improve the skeletal growth of male rats altered by previously given estradiol.
Homocysteine, a new crucial element in the pathogenesis of uremic cardiovascular complications.
Perna AF; Ingrosso D; Castaldo P; De Santo NG; Galletti P; Zappia V
Institute of Biochemistry of Macromolecules and Division of Nephrology, School of Medicine, Second University of Naples, Italy.
Miner Electrolyte Metab (Switzerland) Jan-Apr 1999, 25 (1-2) p95-9
Most large observational studies available today establish that moderate hyperhomocysteinemia, either genetically or nutritionally determined, is an independent risk factor for myocardial infarction, stroke, and thromboembolic disease. This is also true for chronic renal failure patients, who exhibit a high prevalence of hyperhomocysteinemia (85-100%), which reaches high plasma concentrations (20-40 microM, while control values range between 8 and 12 microM). After a renal transplant, homocysteine levels decrease, but tend to be higher than normal. The cause of hyperhomocysteinemia in renal failure is still obscure, since recent data have questioned the previous notion that a net homocysteine renal extraction and/or excretion take place in man. No matter the cause of its increase, the sulfur amino acid homocysteine is thought to induce an increment in cardiovascular risk through three basic biochemical mechanisms: (1) homocysteine oxidation, with H2O2 generation; (2) hypomethylation through S-adenosylhomocysteine accumulation, and (3) protein acylation by homocysteine thiolactone. The final result is membrane protein damage, endothelial damage, and endothelial cell growth inhibition, among other effects. Hyperhomocysteinemia, in general, is susceptible of therapeutic intervention with the vitamins involved in its metabolism. Depending on the cause, vitamin B6, vitamin B12, betaine, and/or folic acid can be effectively utilized. Chronic renal failure patients benefit from folic acid in high dosage: 1-2 mg are usually not effective ('relative folate resistance'), while 5-15 mg reduce homocysteine levels to a 'normative' range (<15 microM) in a substantial group of patients. Good results are also obtained in transplant patients, best with a combination of folic and vitamin B6. The results of the interventional trials focusing on the possible reduction in cardiovascular risk after homocysteine-lowering therapy, both in the general population and in end-stage renal disease, are expected soon, as well as the genetic and biochemical studies in suitable models, with the aim to clarify the cause-effect link suggested by the numerous observational and basic science studies. (24 Refs.)
Dietary folate from vegetables and citrus fruit decreases plasma homocysteine concentrations in humans in a dietary controlled trial.
Brouwer IA; van Dusseldorp M; West CE; Meyboom S; Thomas CM; Duran M; van het Hof KH; Eskes TK; Hautvast JG; Steegers-Theunissen RP
Division of Human Nutrition, Wageningen Agricultural University, 6700 EV Wageningen, The Netherlands.
J Nutr (United States) Jun 1999, 129 (6) p1135-9
Elevated total plasma homocysteine (tHcy) concentrations are considered a risk factor for neural tube defects (NTD) and cardiovascular disease. Supplementation with folic acid decreases the risk of women having children with NTD. In both sexes, it decreases tHcy levels. We investigated the efficacy of natural dietary folate in improving folate and homocysteine status. We performed a 4-wk dietary controlled, parallel design intervention trial with 66 healthy subjects (18-45 y) divided into 3 treatment groups: the dietary folate group, the folic acid group and the placebo group. Each day each group was fed a different diet. The dietary folate group received a diet high in vegetables and citrus fruit (total folate content approximately 560 microgram) plus a placebo tablet. The folic acid group received a diet naturally low in folate (approximately 210 microgram) plus 500 microgram folic acid and placebo tablet on alternate days, i.e., 250 microgram folic acid/d. And the placebo group received the same low-folate diet as the folic acid group plus a placebo tablet. After 4 wk of intervention, folate status improved, and tHcy concentrations decreased in both the dietary folate and the folic acid groups. From the amount of additional folate (350 microgram/d) and folic acid (250 microgram/d) consumed, the relative bioavailability of dietary folate compared to folic acid was calculated to be 60-98%, depending on the endpoint used. In conclusion, increasing the consumption of vegetables and citrus fruit, both good sources of folate, will improve folate status and decrease tHcy concentrations. This may contribute to the prevention of cardiovascular disease and NTD in the general population
[Folic acid supplementation by 200 microgram per day during the periconceptional period: a necessary public health approach to reducing incidence of spina bifida]
Bradai R; Siger D; Chakroun R
Service de Gynecologie-Obstetrique (Pr Raudrant), Hotel-Dieu, Lyon, Paris.
Contracept Fertil Sex (France) Mar 1999, 27 (3) p238-42
The incidence of neural tube closure abnormalities, and particularly Spina-bifida is correlated with a low dietary intake of folic acid, for which the marker is the erythrocyte folate concentration. Initially, preventive policies concerned women treated with anticonvulsant agents and those with a known family history of Spina-bifida. This constituted secondary prevention. The objective of this study was to demonstrate the methods and respective role of secondary and primary prevention in 1998. The evolution away from secondary prevention towards primary prevention, i.e. aimed at all women who intend to conceive has been based upon the fundamental epidemiological estimate that 95% of cases of Spina-bifida occur in babies born to women without a known family history of this type of disorder. The idea that dietary measures alone may suffice to ensure effective prevention is invalid. However, if used in addition to a mean dietary intake of 200 micrograms folic acid a day, the only use of pharmacological or synthetic supplementation of 200 micrograms/day makes it possible to achieve the desired threshold of Dietary Folate Equivalents of 600 micrograms/day. The dose of 200 micrograms/day has been judged by the authors as being the most effective and safe for use on a large scale in the general population. Today, in 1998, the primary prevention of neural tube closure abnormalities is the subject of an international consensus which recommends folate supplementation of 100 to 200 micrograms/day during the periconceptional period. Implementation of this solution in the context of a health education campaign would meet the expectations of many women, in as much as 66% of them have declared that they would be ready to comply with such primary preventive measures.