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Life Extension Magazine

LE Magazine August 2001

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Studies from throughout the world that can help you live longer

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August 2001 Table of Contents

  1. The impact of stroke
  2. Bioavailability of nutrients in the elderly
  3. Low-dose transdermal testosterone therapy improves angina
  4. Isoflavone consumption and CVD factors in postmenopausal women
  5. Fish oil protects against colon cancer
  6. Dietary fatty acids effect on cardiovascular syndrome
  7. SAMe protects mitochondrial injury in liver
  8. Doppler ultrasound for the brain
  9. Vitamin C and chronic heart failure
  10. Vitamin C concentration and atherosclerosis
  11. Deprenyl prevents cell hypoxia caused by neurotoxins
  12. L-arginine, heart rate and oxygen
  13. Deviations in immune system from occupational radiation

1. The impact of stroke

It is estimated that there are 4.5 million deaths a year from stroke in the world and over 9 million stroke survivors. Almost one in four men and nearly one in five women aged 45 years can expect to have a stroke if they live to their 85th year. The overall incidence rate of stroke is around 2 to 2.5 per thousand population. The risk of recurrence over 5 years is 15 to 40%. It is estimated that by the year 2023 there will be an absolute increase of about 30% in the number of those experiencing a first ever stroke compared with 1983. There is a total prevalence rate of around 5 per thousand population. Stroke comprises the major cause of adult disability.

BRITISH MEDICAL BULLETIN, 2000, Vol 56, Iss 2, pp 275-286


2. Bioavailability of nutrients in the elderly

Until a few years ago, little was known about bioavailability of micronutrients in the elderly. It was assumed by many basic investigators and geriatricians that malabsorption of both macronutrients and micronutrients was a common problem among elderly persons. We now know that this is not the case. Elderly persons who malabsorb macronutrients do so because of disease, not because of age.

JOURNAL OF NUTRITION, 2001, Vol 131, Suppl. 4, pp 1359S-1361S


3. Low-dose transdermal testosterone therapy improves angina

Studies suggest that male sex hormones (androgens) induce coronary vasodilatation (increased blood vessel diameter). A study examined the effects of long-term low-dose androgens in 46 men with stable angina (chest pain). The placebo group exercised 2-weeks on a treadmill. The study group took 5 mg testosterone daily by transdermal patch or matching placebo for 12 weeks in addition to their current medication. The treatment with testosterone resulted in a 2-fold increase in androgen levels and a delay before onset of reduction (from 309 seconds at start to 343 seconds after 4 weeks and to 361 seconds after 12 weeks). This change was statistically significant compared with that seen in the placebo group (from 266 seconds at start to 284 seconds after 4 weeks and to 292 seconds after 12 weeks. The magnitude of the response was greater in those with lower starting levels of bioavailable testosterone. There were no significant changes in prostate specific antigen, hemoglobin, lipids or coagulation profiles during the study. There were also significant improvements in perception of pain and acceptance of limitations resulting from physical problems in the testosterone-treated group. Low-dose supplemental testosterone thus reduces exercise-induced myocardial ischemia (insufficient blood flow to the heart muscle) in men with chronic stable angina.

CIRCULATION, 2000, Vol 102, Iss 16, pp 1906-1911


4. Isoflavone consumption and CVD factors in postmenopausal women

Few studies have looked at the cardiovascular disease (CVD) benefit of the usual consumption of dietary isoflavones. A study examined the association between usual dietary isoflavone intake and CVD risk factors, including lipids and lipoproteins, body mass index (BMI) and fat distribution, blood pressure, glucose and insulin in 208 postmenopausal women (aged 45-74). Dietary intake over the past year was assessed with a standardized questionnaire. Isoflavone consumption did not vary by age, exercise, smoking, education or years postmenopausal. The results showed that women with high genistein intake had a significantly lower BMI, waist circumference and fasting insulin level than those with no daily genistein consumption. Genistein, daidzein and total isoflavone intake were each positively associated with HDL cholesterol and oppositely related to insulin level. Thus, dietary soy exhibits protective qualities against cardiovascular disease in postmenopausal women.

JOURNAL OF NUTRITION, 2001, Vol 131, Iss 4, pp 1202-1206


5. Fish oil protects against colon cancer

Ras proteins are critical regulators of cell function, including growth, differentiation, and apoptosis. These are a family of oncogenes, which are genes, which can potentially cause tumor growth. A prerequisite for malignant transformation is membrane localization of the protein. Fish oil, compared with corn oil, decreases Ras membrane localization in the colon and reduces tumor formation in rats given a colon carcinogen. A study investigated whether docosahexaenoic acid (DHA), the major n-3 polyunsaturated fatty acid constituent found in fish oil, compared with linoleic acid (LA), found in corn oil, alters Ras processing and activation in mouse colon cells. The results showed that fish oil, compared with LA, reduces Ras localization to the cell plasma membrane without affecting lipidation. These results may partly explain why dietary fish oil protects against the development of colon cancer.

AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY, 2001, Vol 280, Iss 5, pp C1066-C1075


6. Dietary fatty acids effect on cardiovascular syndrome

A study investigated the effects of omega-3 and omega-6 polyunsaturated fatty acids on the metabolic syndrome associated with cardiovascular disease in rodents fed a high sugar diet. The metabolic syndrome-induced rats showed a significant increase in systolic blood pressure, blood insulin, nonfasting blood triglyceride (lipids) and blood cholesterol levels. Then they received either a omega-3 or omega-6 enriched diet or a control diet during 6 weeks. Those fed the omega-3 enriched diet had a significant reduction in blood pressure and blood insulin and triglyceride levels. Triglyceride levels were also significantly reduced in the omega-6-rich diet animals. Dietary PUFAs have a beneficial effect on the cardiovascular system.

JOURNAL OF NUTRITIONAL BIOCHEMISTRY, 2001, Vol 12, Iss 4, pp 207-212


7. SAMe protects mitochondrial injury in liver

S-adenosylmethionine (SAMe) is a compound with known therapeutic affects on cholestasis (stopping or suppressing bile flow) and liver toxicity. A study investigated the effect of SAMe on the prevention of mitochondrial injury, which was caused by liver ischemia (blood deficiency) and reperfusion (restoration of blood flow). Rodents received either SAMe or placebo 2 hours before ischemia was artificially induced. Results showed that in the placebo-treated ischemic animals, blood aspartate aminotransferase levels (stress marker) increased at 1 hour and at 5 hours of reperfusion. However, they were reduced by pre-treatment with SAMe. In addition, lipid peroxidation in mitochondria was elevated in the control group, but this elevation was weakened by SAMe. In contrast, mitochondrial glutamate dehydrogenase (enzyme that converts glutamate) activity and reduced glutathione (endogenous antioxidant) concentration both decreased in the control group, and this decrease was also inhibited by SAMe. Levels of liver ATP in the control group were found to be 42% lower 5 hours after reperfusion. However, treatment with SAMe elevated these ATP levels. SAMe increased the concentration of adenosine but inhibited the accumulation of hypoxanthine (a free radical marker) in the ischemic liver. Thus, SAMe protects against mitochondrial injury, which prevents mitochondrial free radical stress and improves liver energy metabolism.

JOURNAL OF HEPATOLOGY, 2001, Vol 34, Iss 3, pp 395-401


8. Doppler ultrasound for the brain

Transcranial Doppler ultrasound allows measurements of blood flow velocity to be made from the vessels in the cerebrum of the brain. The major advantages of transcranial Doppler ultrasound are that it is non-invasive, relatively cheap, does not use radiation and can be performed with portable machines. It allows monitoring for prolonged periods, and has a high temporal resolution making it ideal for studying dynamic cerebrovascular responses. It has recently been demonstrated that it can be used to detect circulating blood clots in the brain. These cannot be detected by any other currently available imaging modality.

BRITISH MEDICAL BULLETIN, 2000, Vol 56, Iss 2, pp 378-388


9. Vitamin C and chronic heart failure

Chronic heart failure (CHF) is a state subject to blood clotting, which may relate to increased platelet aggregation (clumping), endothelial (cells lining blood vessels) dysfunction and increased oxidative stress. A study investigated the effect of vitamin C (2 g or placebo) in CHF on platelet aggregation and platelet responsiveness to the aggregatory effects of two nitric oxide (NO) donors. It also examined parameters of oxidative stress and endothelial function in 10 participants with CHF. Vitamin C enhanced the inhibition of platelet aggregation caused by the NO donors (62.7 to 82.7 4.8%) and tended to increase responses to second NO donor (40.5 to 53.4). The beneficial effect of vitamin C on platelet responsiveness was oppositely related to the platelet aggregation caused by the NO donors. Vitamin C also increased flow-mediated dilation (FMD) in the brachial (arm) artery (1.9 to 5.8) and reduced free radicals by 19%, which were derived from blood lipids. Thus, in those with chronic heart failure, intravenous administration of vitamin C enhances platelet responsiveness to the aggregatory effects of NO donors and improves endothelial cell function. This suggests a potential role for vitamin C as a therapeutic agent in CHF.

JOURNAL OF CARDIOVASCULAR PHARMACOLOGY, 2001, Vol 37, Iss 5, pp 564-570


10. Vitamin C concentration and atherosclerosis

Peripheral arterial disease (PAD) is a severe atherosclerotic condition frequently accompanied by inflammation and production of free radicals. A study investigated vitamin C levels in three groups: 1) 85 people with PAD, 2) 106 hypertensives without PAD, and 3) the control group - 113 healthy people. The results showed lower vitamin C concentrations (14%) among those with PAD, despite comparable smoking status and dietary intake with the other groups. Blood C-reactive protein (CRP) concentrations were significantly higher (26%) in PAD participants; higher levels of vitamin C corresponded with lower CRP. C-reactive protein is produced in the liver during inflammation in various diseases, particularly immune diseases. Normally, it should be negative in the blood. Thus, a vitamin C deficiency in those with PAD was associated with high CRP level and smoking, as well as a shorter distance on a treadmill test. Future studies attempting to relate vitamin C levels to disease occurrence should include in their analysis an inflammatory marker such as CRP.

CIRCULATION, 2001, Vol 103, Iss 14, pp 1863-1868


11. Deprenyl prevents cell hypoxia caused by neurotoxins

A study looked at 2 strong mitochondrial toxins underlying Parkinson's disease and measured the extracellular lactate levels as a marker for the cell hypoxia (reduction of oxygen supply) in the brain of freely moving rats. The results showed that the perfusions (pouring through a vessel or over an organ) with the 2 toxins increased extracellular lactate levels in a dose-dependent manner. The increase in extracellular lactate levels was considered the reflection of the cell damage resulted from the impairment of mitochondrial function. These increases in lactate levels were significantly prevented when perfused with deprenyl, a selective monoamine oxidase (MAO)-B inhibitor. (MAO inhibitor is an antidepressive drug that interferes with the action of the enzyme, monoamine oxidase, and thus slows the breakdown of neurotransmitters in the central nervous system, such as serotonin, dopamine and norepinephrine, thus affecting mood). The results suggested that deprenyl would rescue nerve cells from these toxins through the direct influence on the mitochondrial electron transport.

NEUROSCIENCE LETTERS, 2001, Vol 302, Iss 2-3, pp 65-68


12. L-arginine, heart rate and oxygen

A study assessed whether L-arginine could improve some cardiovascular and metabolic parameters in anaesthetized hemorrhaged (bleeding) rabbits. The administration of L-arginine (300 mg/kg) increased heart rate (10%) and decreased hemoglobin (oxygen carrying protein) saturation in the veins with oxygen (app. 23%) 1 hour after bleeding stopped, without negative changes in arterial pressure. Thus, L-arginine produces beneficial effects on the heart rate and tissue oxygen extraction in rabbits with excessive bleeding.

PHARMACOLOGICAL RESEARCH, 2001, Vol 43, Iss 4, pp 321-327


13. Deviations in immune system from occupational radiation

The toxic effects to the genes due to occupational exposure to ionizing and non-ionizing radiation were investigated in 25 physicians and nurses working in hospitals and in 20 individuals working at radio-relay stations. The data showed that total number of chromosome aberrations in people exposed to ionizing and radio frequency radiation were both equally higher than those of non-irradiated individuals. The average numbers of aberrations (11.8 x 10(-3) and 14.8 x 10(-3) per cell, respectively) were significantly higher than 4.2 x 10(-3), in the unexposed control group. Chromosomal fragments were also frequent (4.8 x 10(-3) and 6.25 x 10(-3), respectively, vs. 0.52 x 10(-3) in the control group. The frequency of chromatid (strands formed from chromosome pairing) breaks increased only after ionizing radiation, (3.8 x 10(-3) vs. 0.26 x 10(-3) for controls). There was also a positive degree of association between the total number of chromosome aberrations and cumulative 6-year dose of radiation. The results emphasize the dangerous effects of prolonged exposure to both types of radiation.

ACTA MEDICA OKAYAMA, 2001, Vol 55, Iss 2, pp 117-127



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