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Life Extension Magazine

LE Magazine April 2000

MEDICAL UPDATES
Studies from throughout the world that can help you live longer

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April 2000
Table Of Contents

  1. Gamma-tocopherol vs. blood clotting
  2. Vitamin B-12 deficiency: A new risk factor for breast cancer?
  3. Tea flavonoids may protect against atherosclerosis
  4. Protective effect of N-acetylcysteine (NAC)
  5. Anti-platelet activity of soy sauce
  6. Oral vitamin c benefits arteries and platelets
  7. Risk factors and outlook for stroke
  8. Plant foods, antioxidants, and prostate cancer risk
  9. Longevity and decreased metabolic rate
  10. Inhibition of telomerase limits the growth of human cancer cells
  11. Long-term treatment prevents HIV expansion

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  1. Gamma-tocopherol vs. blood clotting

    Full source: JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY, 1999, Vol 34, Iss 4, pp 1208-1215

    A study indicates that both alpha- and gamma-tocopherol (vitamin E): 1) decrease blood platelet aggregation, thereby delaying blood clot formation in arteries (perhaps by an increase in endogenous antioxidant activity), 2) decrease superoxide free radical generation in arteries, lipid peroxidation and LDL oxidation, and 3) increase naturally produced superoxide dismutase (SOD) activity (a free radical scavenger). Gamma-tocopherol is significantly more potent than alpha-tocopherol in these effects.

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  2. Vitamin B-12 deficiency: A new risk factor for breast cancer?

    Full source: NUTRITION REVIEWS, 1999, Vol 57, Iss 8, pp 250-253

    An increased risk of breast cancer was observed among postmenopausal women, having low levels of vitamin B-12. This is the first observation to suggest that B-12 status may influence breast cancer growth and therefore may be a risk factor for breast cancer prevention that can be modified to achieve positive results.

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  3. Tea flavonoids may protect against atherosclerosis

    Full source: ARCHIVES OF INTERNAL MEDICINE, 1999, Vol 159, Iss 18, pp 2170-2174

    A study indicates a protective effect of tea drinking against ischemic heart disease. Tea is the major dietary source for flavonoids in Western populations. The association of drinking tea with the severity of hardening of the aorta (main artery) was studied in 3,454 men and women 55 years and older who were free of cardiovascular disease at the start of the study. There was a significant, association of low tea intake with severe aortic atherosclerosis and vice versa. The odds ratios of not getting atherosclerosis increased from 46% for drinking 1-2 cups of tea to 69% for drinking more than 4 cups per day. The associations were stronger in women than in men.

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  4. Protective effect of N-acetylcysteine (NAC)

    Full source: DRUG AND ALCOHOL DEPENDENCE, 1999, Vol 57, Iss 1, pp 61-67

    The use of N-acetylcysteine (NAC) 7 days after drinking alcohol: 1) reduced lipid peroxidation, 2) elevated the reduced glutathione level in the liver and in red blood cells, 3) and increased the activity of reduced glutathione-related enzymes in the blood, red blood cells and in the liver. Without NAC, drinking alcohol increased the concentration of the lipid peroxidation products, decreased the liver glutathione activities, and reduced the glutathione concentration and total antioxidant status. Alcohol is oxidized to formaldehyde and then to formate. This process is accompanied by formation of superoxide anion and hydrogen peroxide (both causing potential free radical damage). These results suggest that NAC exerts its protective effect by acting as a precursor for glutathione, the body's natural antioxidant, and as a free radical scavenger.

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  5. Anti-platelet activity of soy sauce

    Full source: JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, 1999, Vol 47, Iss 10, pp 4167-4174

    A study showed that soy sauce inhibited platelet aggregation (which causes blood clots). It produced a 50% inhibition of platelet aggregation response, which had been caused by the hormone, epinephrine, platelet-activating factor, collagen, adenosine 5'-diphosphate, and thrombin, respectively. Its inhibitory effect was much greater than that of 1- methyl-beta-carboline on platelet aggregation by all the tested causal agents. The significant amounts of both anti-platelet compounds were uniformly contained in commercially available soy sauce. From these results, soy sauce may be referred to as functional seasoning containing alkaloidal components with the potent preventive effect on the formation of blood clots.

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  6. Oral vitamin c benefits arteries and platelets

    Full source: JOURNAL OF CARDIOVASCULAR PHARMACOLOGY, 1999, Vol 34, Iss 5, pp 690-693

    Atherosclerosis is associated with stiffening of arteries and increased platelet activation. This is partly a result of reduced bioavailability of nitric oxide (NO). NO normally has a variety of protective effects on blood vessels and platelets. Increased levels of oxygen free radicals are a feature of atherosclerosis that contributes to reduced NO bioavailability and might lead to increased arterial stiffness and platelet activation. Vitamin C, being a dietary antioxidant, inactivates oxygen free radicals. After acute oral administration of vitamin C (2 g), vitamin C blood concentrations increased from 42 to 104 (mu M) at 6 hours after oral administration. It was associated with a significant reduction in augmentation index, which is a measure of arterial stiffness (by 9.6), and ADP-induced platelet aggregation (by 35). There was no change in these parameters after placebo was administered. Vitamin C, therefore, appears to have beneficial effects, even in healthy subjects. The mechanism responsible is likely to involve protection of nitric oxide from inactivation by oxygen free radicals. If similar effects are observed in patients with atherosclerosis or risk factors, vitamin C supplementation might prove an effective therapy in cardiovascular disease.

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  7. Risk factors and outlook for stroke

    Full source: NEUROLOGY, 1999, Vol 53, Iss 7, Suppl. 4, pp S15-S24

    Stroke is a leading cause of death and illness, but incidence rates vary dramatically from one population to another. The reasons for this heterogeneity are being explored in several large-scale studies around the world. Much of the heterogeneity in stroke can be related to the prevalence of risk factors, but some populations have a higher stroke incidence than would be predicted from risk factor levels. Hypertension, including borderline hypertension, is probably the most important stroke risk factor based on degree of risk and prevalence. However, heart disease, cigarette smoking, diabetes, physical inactivity, and high levels of alcohol consumption are also strongly related to stroke risk. High levels of blood cholesterol and homocysteine may also increase stroke risk. Risk of death after stroke is highest within the first 30 days but remains elevated to a degree that depends on the type of stroke, and other illnesses present. Lacunar strokes have the best short- and long-term prognoses. Strokes due to large-vessel atherosclerosis frequently worsen; these and cardioembolic strokes have the poorest long-term prognosis. The risk for recurrence is also highest within 30 days after a first stroke, depending on the type of cell death, history of hypertension, and blood glucose levels on admission. Predictors of the stroke reoccurring include heart disease, hypertension, and heavy alcohol use. Only about half of stroke survivors are independent 6 months after a stroke, and quality of life is decreased.

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  8. Plant foods, antioxidants, and prostate
    cancer risk

    Full source: NUTRITION AND CANCER-AN INTERNATIONAL JOURNAL, 1999, Vol 34, Iss 2, pp 173-184

    Certain dietary components of plant origin may reduce the risk of prostate cancer. A study consisted of 617 cases of prostate cancer and 636 disease free individuals as controls from Ontario, Quebec, and British Columbia. It found a decreasing, statistically significant association of prostate cancer with increased consumption of green vegetables (-46%), tomatoes (-36%), beans/lentils/nuts (-31%), and cruciferous vegetables (-31%). Higher intakes of citrus and non-citrus fruit were also associated with lower prostate cancer. Among the grains, refined-grain (white) bread intake was associated with a decrease in risk (-35%). However, whole-grain breakfast cereals were associated with a higher risk for prostate cancer.

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  9. Longevity and decreased metabolic rate

    Full source: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1999, Vol 96, Iss 20, pp 11399-11403

    In worms, longevity is increased when the metabolic rate goes down and vice versa. Mutations of the soil worm, Caenorhabditis elegans that increase its longevity could define genes involved in a process specific for aging. The actions from these gene mutations could reduce animal metabolic rate and increase longevity consequently. Environmental conditions that reduce the metabolic rate of the worm, C. elegans also extend longevity. In a study, it was found that the metabolic rate of long-lived C. elegans mutations is reduced compared with that of worms found in the wild. However, when a certain gene was "turned off," it restored normal longevity to the long-lived mutants along with restoring the normal higher metabolic rate. Thus, the increased longevity of some long-lived C. elegans mutants may be the result of a lowering of their metabolic rate, rather than an alteration of a genetic pathway that leads to enhanced longevity. The actual mechanism responsible for the relationship between metabolic rate and longevity remains unknown.

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  10. Inhibition of telomerase limits the growth of human cancer cells

    Full source: NATURE MEDICINE, 1999, Vol 5, Iss 10, pp 1164-1170

    A mutation of the human enzyme, telomerase results in the blocking of telomerase activity, reduction in telomere length and death of tumor cells. A study showed that the action of this mutant form of telomerase eliminated the growth of tumors in the body. Telomerase is an enzyme (in cell nucleus) that maintains the protective structures at the ends of chromosomes (chromosomes divide during cell division), called telomeres. In most normal human cells, the action of telomerase is repressed, and consequently telomeres shorten progressively with each cell division, a process recently thought to be a factor in the present human maximum life span. In contrast, most human tumors utilize telomerase, resulting in stabilized telomere length. Thus, for tumor cells to proliferate, they must maintain the telomeres. The disruption of telomere maintenance limits cellular life span in human cancer cells. This makes the human telomerase reverse transcriptase enzyme an important target for the development of anti-cancer therapies.

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  11. Long-term treatment prevents HIV expansion

    Full source: AIDS RESEARCH AND HUMAN RETROVIRUSES, 1999, Vol 15, Iss 15, pp 1333-1338

    Prolonged anti-viral therapy with a simple, well-tolerated combination of two affordable drugs can lead to sustained control of HIV, normalization of immune system parameters, and specific anti-HIV immune response. In a study treating the HIV virus, the drugs, hydroxyurea, and didanosine suppressed HIV replication for more than 2 years, with no viral breakthrough, in chronically infected patients. The fact that a two-drug combination reduced the amount of virus in the system was unusual, because the continuous gradual decrease in virus in the bloodstream persisted although there was residual viral replication. However, there was not a large increase in CD4(+) T cell counts (immune cells). On the other hand, unlike those of patients treated by other therapies, the CD4(+) T lymphocytes were very successful in combating the HIV virus. They launched a vigorous HIV-specific helper T cell response in half of these patients. In addition, the percentages of CD4(+) and CD8(+) T lymphocytes were the same as from those in uninfected individuals.

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