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Life Extension Magazine

LE Magazine March 1999

MEDICAL UPDATES

Studies from throughout the world that can help you live longer


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March 1999
Table Of Contents

  1. DHEA protects low density lipoproteins against peroxidation by free radicals
  2. Melatonin inhibits iron-induced epileptic discharges
  3. Pesticides may increase breast cancer risk
  4. The effect of melatonin chronic treatment upon macrophage and lymphocyte metabolism and function in Walker-256 tumour-bearing rats
  5. Olive oil health benefits questioned
  6. Obesity linked with pancreatic cancer
  7. "Fat hormone" stimulates blood vessel growth
  8. Moderate wine consumption cuts stroke risk
  9. Hormone therapy for patients with locally advanced prostate carcinoma
  10. Recent use of hormone replacement therapy and the prevalence of colorectal adenomas


  1. DHEA protects low density lipoproteins against peroxidation by free radicals

    Full source:Atherosclerosis, 1998, Vol 136, Iss 1, pp 99-107

    Oxidized low density lipoproteins (LDL) are believed to play a central role in the events that initiate atherosclerosis. Antioxidants have been shown to decrease the oxidation of LDL, leading to the diminution of atherosclerosis. It is well-known that decreased levels of dehydroepiandrosterone (DHEA) are linked to the development of atherosclerosis. This study looked at the modulation of the oxidation of LDL by DHEA. LDL were obtained from 10 healthy subjects and oxidized by free radicals produced by gamma-radiolysis of ethanol-water mixtures. It was found that DHEA was able to inhibit the oxidation of LDL by reducing over 90% of the conjugated dienes and TEARS (thiobarbituric acid-reactive substances) formation, reducing the vitamin E disappearance and significantly decreasing the chemotactic activity (cellular movement in response to chemicals) of oxidized LDL in the presence of DHEA towards monocytes. The results suggest that DHEA exerts its antioxidative effect by protecting the endogenous vitamin E of LDL.



  2. Melatonin inhibits iron-induced epileptic discharges

    Full source: Epilepsia, 1998, Vol 39, Iss 3, pp 237-243

    Injection of iron ion into the cerebral cortex of the brain induces recurrent seizures and epileptic discharges in the electrocorticogram (record of electrical activity). Melatonin exerts free radical scavenging properties. This study examined 1) the protective effect of melatonin against in vitro iron-induced oxidative damage in homogenates from rat cerebral cortex, by measuring the concentration of thiobarbituric acid reactive substances (TBARS), as an index of oxidative damage and 2) the effect of melatonin on the appearance of epileptic discharges in the EEG following injection of FeCl3 (iron) into the sensorimotor cortex in anesthetized rats, and by measuring the concentration of TBARS in the brain tissue. The iron increased the concentration of TBARS in brain, and melatonin reduced the iron-induced rise in TBARS in a dose-response fashion. Pretreatment with melatonin suppressed or delayed the development of iron-induced epileptic discharges and decreased the concentration of TBARS in brain tissues. The results suggest that iron ion generates oxygen free radical species that induce neuronal macromolecular peroxidation and seizure, and that melatonin inhibits iron-induced seizures by scavenging free radicals.



  3. Pesticides may increase breast cancer risk

    Full source:The Lancet 1998;352;1816-1820

    Certain pesticides, known as organo-chlorides, which are found in agricultural and industrial products, have a weak estrogen-like effect, which may play a role in the development of breast cancer. To clarify this link, Danish researchers measured levels of the chemicals in blood from more than 7,700 women and assessed their risks of breast cancer over 17 years. The team studied 240 of these women who developed breast cancer and 477 who did not. The risk of breast cancer was twice as high in women with the highest (blood) concentrations of dieldrin (an organochloride) as that in women with the lowest concentrations. Note: This report confirms our conclusion about the link of organochlorides to breast cancer. We reviewed the literature a few years ago, for our book, How To Prevent Breast Cancer (available at Amazon.com). Once again, one of our recommendations holds true years later. These chemicals act as forms of estrogen, so a higher risk for cancers that are stimulated by estrogen is to be expected



  4. The effect of melatonin chronic treatment upon macrophage and lymphocyte metabolism and function in Walker-256 tumour-bearing rats

    Full source: Journal of Neuroimmunology, 1998, Vol 82, Iss 1, pp 81-89

    Melatonin is the main hormone involved in the neuroendocrine-immune axis. It also presents antitumour activity. To evaluate the role of melatonin on the progression of Walker-256 tumour in rats we determined the effect of the hormone on some biochemical and functional aspects of macrophage and lymphocytes from cachectic rats. An important finding observed in immune cells from tumour-bearing (TB) rats is the impairment on glutamine and glucose metabolism in such cells. These changes are very similar to those observed in pinealectomized rats (PNX). The increased production of lactate and the flux of glucose through the Krebs cycle and the reduction in glutamine consumption seems to be involved in the immunosuppresion presented in the TB and PNX animals. Melatonin treatment restored the changes observed in the metabolism of glucose and glutamine and stimulated the proliferation of lymphocytes from tumour-bearing rats. The results indicate that the effect of melatonin upon tumour growth involves the stimulation of the immune system by the hormone. (c) 1998 Elsevier Science B.V.



  5. Olive oil health benefits questioned

    Full source: Arteriosclerosis, Thrombosis and Vascular Biology 1998;18:1818-1827

    Although past reports have suggested that monounsaturated fats, such as those found in olive oil, may protect against heart disease, a new study in mice suggests that this may not be true. In this study, mice fed a diet containing monounsaturated fats were more likely to develop atherosclerosis than mice fed a diet containing saturated fat, which is found in butter and meat, or mice fed polyunsaturated fat, the type of fat found in vegetable oil. The mice were prone to heart disease because they were genetically engineered to have high blood levels of LDL ("bad") cholesterol. Mice fed a regular rodent diet had the least amount of atherosclerosis, followed by mice fed polyunsaturated fat. Linoleic acid-rich oils such as corn and soybean appear to be more protective against coronary heart disease than olive or canola oil. The research team will study dietary fats over the next five years. Note: Another reason why we should be attempting to get more omega-3 essential fatty acids (flaxoil and fish oil) in our diet, rather than olive oil. The health benefits of the Mediterranean diet may be due to some other factor than olive oil. Perhaps cooking with canola oil (rape seed oil) is more healthy than olive oil.



  6. Obesity linked with pancreatic cancer

    Full source: Journal of the National Cancer Institute 1998;90:1710-1719

    The results of this new study suggest that obesity not only increases the risk of diabetes and heart disease, it also appears to increase the risk for pancreatic cancer as well. The researchers compared the dietary habits and body characteristics of 436 people with pancreatic cancer and 2,003 healthy people the same age. Obesity was associated with a 50% to 60% increase in risk of pancreatic cancer. There was also an association between calorie intake and cancer risk. The finding was true regardless of gender and for both blacks and whites. This reveals for the first time a significant interaction between body mass index and total caloric intake (energy balance) in relation to pancreatic cancer risk. It also suggests that fewer meals and high intake of cruciferous vegetables offered protection against pancreatic cancer. Note: Smoking is a very strong link to cancer of the pancreas. Michael Landon, the late actor, died of this cancer; he was said to have smoked up to three packs of cigarettes daily for most of his life. .



  7. "Fat hormone" stimulates blood vessel growth

    Full source: Science 1998;281:1582, 1683-1685

    Leptin has generated great scientific interest in recent years due to its apparent role in fat metabolism and weight gain. According to researchers, it may also play a role in angiogenesis, the development of blood vessels. At Yale University experiments have demonstrated leptin's "angiogenic activity." However, the hormone may also perform another important physiological function. When leptin was added to human endothelial cells cultured in the laboratory, the hormone "promoted the formation of capillary-like tubes," mimicking the development of tiny blood vessels, a process known as angiogenesis. Leptin also caused a vigorous angiogenic response "in the corneas of rats." Noting its association with fat cells, the authors speculate that leptin may help spur the production of blood vessels needed for the growth of fat tissue. The most intriguing possibilities lie in the role angiogenesis might play in cancer development and progression. Newly-developed anticancer drugs, such as endostatin, work by preventing tumor angiogenesis, effectively "starving" cancer cells of their blood supply. Tumors make angiogenic factors, so it's not at all remote to think that they may be making leptin. With cancer there is a lack of appetite and weight loss that occurs very rapidly and severely. The researchers speculate that leptin may play some role in this weight loss.



  8. Moderate wine consumption cuts stroke risk

    Full Source: Journal of the American Heart Association 1998:29:2467-2472

    According to a 16-year study of 13,300 men and women in Denmark, the moderate consumption of wine is associated with a reduced risk of stroke. (Moderate is defined as up to two 4 oz. drinks in a 24 hour period). Compared with abstainers, individuals who said they drank wine on a monthly, weekly, or daily basis had a 16%, 34%, and 32% reduced risk of stroke, respectively. The researchers believe wine's protective effects may be linked to disease-fighting compounds other than alcohol such as flavonoids and tannins. The researchers found "no association between intake of beer or spirits on risk of stroke." They speculate that drinking patterns specific to wine lovers may also influence cardiovascular health. One recent study concluded that mealtime alcohol consumption reduced unhealthy alterations in blood composition that can occur after eating. Note: In a press release, the American Heart Association notes that it "does not recommend that individuals start drinking to reduce their risk of heart disease and stroke." Experts point out that excessive drinking can actually raise the likelihood of cardiovascular disease, heart attack, and stroke.



  9. Hormone therapy for patients with locally advanced prostate carcinoma

    Full Source:Cancer, 1998, Vol 82, Iss 6, pp 1112-1117

    Locally advanced prostate carcinoma is usually not curable with surgery or radiation therapy. Primary hormone therapy is an alternative therapeutic option, but contemporary prospective studies of the outcomes of such therapy are not available. This study looked at gonadal androgen ablation with deferred antiandrogen therapy in 103 men with prostate carcinoma. Each patient experienced regression of the primary tumor, and none experienced significant sickness from the primary tumor during the study period. [The projected 5-year cause specific, metastasis free PSA, disease free (no PSA elevation > 1.0 ng/mL after beginning of antiandrogen therapy), and all-cause survival rates were 84%, 84%, 68%, and 58%, respectively]. Thus, primary hormone therapy is a reasonable treatment option for locally advanced prostate carcinoma in elderly men or in men with significant coexistence of two or more disease processes who request therapeutic intervention



  10. Recent use of hormone replacement therapy and the prevalence of colorectal adenomas

    Full Source: Cancer Epidemiology Biomarkers & Prevention 1998, Vol 7, Iss 3, pp 227-230

    The etiological role of hormone replacement therapy (HRT) (including estrogen only, combined estrogen-progesterone, and progesterone only) in colorectal neoplasia remains unclear. Several large studies have reported a reduced risk of colorectal cancer among HRT users; however, other studies have given inconsistent results. This study examined the association between hormone replacement therapy (HRT) and colorectal adenomatous polyps, precursors of colorectal cancer, among female participants. Subjects were members of a prepaid health plan in Los Angeles who underwent sigmoidoscopy (examination of the interior of the sigmoid colon) in 1991-1993. A total of 187 histologically confirmed cases and 188 controls, ages 50-75 years, were included in the analysis. Compared with women who did not use HRT during the year before sigmoidoscopy, recent users had an adjusted odds ratio of 0.57 (95% confidence interval, 0.35-0.94). Duration of use was inversely related to the prevalence of colorectal adenomas. There was a odds ratio of 0.49 (95% confidence interval, 0.25-0.97) for use of 5 years or more. These results support a protective effect of HRT on colorectal benign tumors.

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