Weight Loss Sale

Life Extension Magazine

LE Magazine December 2001

image

Studies from throughout the world that can help you live longer

Click here to access this year's Medical Updates.

Click here to access the Medical Update Archives.

Click here to access the Complete Scientific Abstracts Online.


December 2001 Table of Contents

  1. Ginkgo's effects on aging nerve cells in the eye
  2. Loss of energy from seizures linked to free radicals
  3. CoQ10 level low in heart and liver of diabetics
  4. DHEA-S causes an increase in melatonin secretion
  5. Nasal spray prevents recurrence of osteoporotic fractures
  6. Deprenyl improves cardiac function
  7. Effect of HRT on the arteries in perimenopausal women
  8. Cancer and Mediterranean dietary traditions
  9. Prostate cancer risk and physical activity
  10. Raloxifene vs. tamoxifen on lipid metabolism

1. Ginkgo's effects on aging nerve cells in the eye

Age-related changes of mitochondria (cell organelles that produce energy) were studied in glial cells of the retina of the eye from guinea pigs fed with or without externally applied ginkgo biloba extract (GBE), an established free radical scavenger. When cell mitochondria from aged animals were compared with those from young adults, they displayed (1) a diminished number of well-defined cristae, (2) a reduced membrane potential and (3) a slightly reduced index of vitality. Cell mitochondria were also studied in aged guinea pigs that had been fed daily by ginkgo biloba during the last two months before they were sacrificed. The results showed that the cell mitochondria displayed (1) many well-defined cristae, compared with mitochondria from untreated aged animals, (2) a significantly enhanced membrane potential and (3) a significantly enhanced index of vitality. Thus, the results suggest that many but not all structural and functional parameters of aging retinal cell mitochondria are impaired by accumulating free radical damage, and that externally applied radical scavengers may protect these organelles from the damaging actions of free radicals. Ginkgo biloba treatment enhances the intrinsic glutathione (endogenous antioxidant) content of aged guinea pig retinal cells.

OPHTHALMIC RESEARCH, 2000, Vol 32, Iss 5, pp 229-236


2. Loss of energy from seizures linked to free radicals

Impaired energy metabolism may play a critical role in the nerve injury caused by kainic acid (KA) induced by epilepsy. Following an acute dose of KA, rats developed epilepsy within one hour. Rats were sacrificed 1 or 72 hours after the onset of epilepsy. Control (not given KA) values were significantly higher in cortex (outer layer, 23-32%) than in other brain regions. Within one hour, seizures caused a marked decline in ATP (44-56%), PCr (49-64%), total adenine nucleotides (TAN, 45-50%) and total creatine compounds (TCC, 32-51%). Within three days, the hippocampus showed the greatest recovery, as the reduced values returned to normal. However, pretreatment of rats with vitamin E for three days (which did not prevent seizure activity), weakened the depletion of high-energy phosphates, caused by KA. Thus, the depletion of energy metabolites caused by KA-induced seizures may be linked to toxicity mediated by free radical stress.

PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 2000, Vol 440, Iss 5, Suppl. S, pp R160-R162


3. CoQ10 level low in heart and liver of diabetics

The dysfunction in the mitochondria of cells and free radical stress are involved in the development of diabetic complications. Coenzyme Q (COQ10) has an important function in mitochondrial bioenergetics and is a powerful antioxidant. COQ10 regenerates vitamin E to its active form and prevents atherogenesis (thickening of the arteries) by protecting low-density lipoproteins (LDL) against oxidation. A study looked at whether the experimentally induced diabetes is associated with changes in the content of endogenous antioxidants (vitamin E and COQ10) and in the intensity of lipoperoxidation in the blood and heart and liver mitochondria. Diabetic rats were administered insulin once a day for eight weeks. The concentrations of glucose, cholesterol, vitamin E and CoQ10 homologues in the blood of the diabetic rats were increased. In heart and liver mitochondria of the diabetic rats, there was an increased concentration of vitamin E, however, the concentration of COQ10 decreased. The formation of malondialdehyde (a marker of free radical stress) was enhanced in the blood and heart mitochondria. Diabetes is associated with increased lipoperoxidation, in spite of the increased blood concentrations of antioxidants vitamin E and CoQ10. An important finding here is that heart and liver mitochondria from the diabetic rats contain less CoQ10 in comparison with the controls. Thus, the deficit of CoQ10 can participate in disturbances of mitochondrial energy metabolism of diabetics.

PHYSIOLOGICAL RESEARCH, 2000, Vol 49, Iss 4, pp 411-418


4. DHEA-S causes an increase in melatonin secretion

Steroid hormones affect various metabolic activities, including melatonin synthesis. A study looked at the effects of dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEA-S), two steroids with weak androgen potency, on the levels of melatonin released by rat pineal glands removed in the middle of the light and dark spans. Result showed that DHEA-S had a direct action on beta-adrenergic-stimulated melatonin release. DHEA-S increased melatonin secretion by 50% to 80% dose-dependently in pineal glands obtained during the light span. This effect depended on the circadian stage, because at night, only the highest concentration of DHEA-S increased melatonin secretion by 25%. DHEA had no effect on melatonin release in pineals obtained during the light span. This work shows that DHEA-S but not DHEA was able to stimulate melatonin secretion by adrenergic-stimulated pineals removed during the light phase.

STEROIDS, 2000, Vol 65, Iss 9, pp 491-496


5. Nasal spray prevents recurrence of osteoporotic fractures

A study determined whether salmon calcitonin nasal spray (100, 200, or 400 IU) reduced the risk of new vertebral fractures in 1,255 postmenopausal women with osteoporosis. They also received elemental calcium (1,000 mg) and vitamin D (400 IU) daily. During five years, 1,108 participants had at least one follow-up radiograph. A total of 783 women completed three years of treatment, and 511 completed five years. The results showed that the 200-IU dose of salmon calcitonin nasal spray significantly reduced the risk of new vertebral fractures by 33% compared with placebo. In the 817 women with one to five prevalent vertebral fractures at enrollment, the risk was reduced by 36%. The reductions in vertebral fractures in the 100-IU (15%) and the 400-IU (16%) groups were not significantly different from placebo. Lumbar spine bone mineral density (BMD) increased significantly from start (1% to 1.5%) in all active treatment groups. Bone turnover was inhibited by 12% in the 200-IU group and by 14% in the 400-IU group as compared with placebo. Thus, salmon calcitonin nasal spray at a dose of 200 IU daily significantly reduces the risk of new vertebral fractures in postmenopausal women with osteoporosis.

Am J Med. 2000;109:267-276


6. Deprenyl improves cardiac function

Deprenyl has been shown to have neuroprotective properties. Deprenyl may be beneficial in heart failure that is characterized by increased sympathetic nervous activity. Twenty-seven rabbits with rapid heart beating (360 beats/min, 8 wk) and twenty-three rabbits with normal beating were randomly assigned to receive deprenyl (1 mg/day, 8 wk) or placebo. Rapid beating increased blood norepinephrine (NE, neurotransmitter) and decreased shortening of the heart left ventricle, baroreflex sensitivity, cardiac sympathetic nerve terminal profiles, cardiac NE uptake activity, and heart wall beta-adrenoceptor density. Deprenyl administration to animals with rapid ventricular beating weakened the increase in blood NE and decreases in shortening, baroreflex sensitivity, sympathetic nerve profiles, NE uptake activity and beta-adrenoceptor density. Thus, deprenyl appears to exert a heart neuroprotective effect in cardiomyopathy. The effect is potentially beneficial because deprenyl not only improves heart function but also increases baroreflex (sensory nerves stimulated by pressure changes) sensitivity in heart failure.

AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, 2000, Vol 279, Iss 3, pp H1283-H1290


7. Effect of HRT on the arteries in perimenopausal women

A study assessed the 2-year effects of hormone replacement therapy (HRT) compared to placebo on mechanical arterial properties in 99 perimenopausal women from the general population. They used a combined regimen of oral 17 beta-oestradiol and desogestrel (17 beta E-2-D) or combination of conjugated equine oestrogens and norgestrel (CEE-N). The results showed that for systolic blood pressure (SBP), diastolic blood pressure (DBP) and artery diameter, no changes were found. No significant differences in changes in distensibility were found between perimenopausal women using 17 beta E-2-D or CEE-N and women using placebo after 6 and 24 months.

ATHEROSCLEROSIS, 2000, Vol 152, Iss 1, pp 149-157


8. Cancer and Mediterranean dietary traditions

The overall incidence of cancer in Mediterranean countries is lower than in Scandinavian countries, the United Kingdom and the United States. This is because of the lower incidence among Mediterranean countries of cancer of the bowel, breast, endometrium and prostate. These forms of cancer have been linked to dietary factors, particularly low consumption of vegetables and fruit, and to a certain extent, high consumption of meat. The traditional Mediterranean diet is characterized by high consumption of foods of plant origin, relatively low consumption of red meat, and high consumption of olive oil, which in several studies has been reported to be more beneficial against cancer than other forms of added lipids. It can be calculated that up to 25% of the incidence of colon and rectal cancer, 15% of the incidence of breast cancer, and 10% of the incidence of prostate, pancreas and endometrial cancer could be prevented if the populations of highly developed Western countries could shift to the traditional healthy Mediterranean diet.

CANCER EPIDEMIOLOGY BIOMARKERS & PREVENTION, 2000, Vol 9, Iss 9, pp 869-873


9. Prostate cancer risk and physical activity

A study looked at the relationship of prostate cancer to physical activity among 5,377 African-American and Caucasian participants in the National Health and Nutrition Examination Survey I group. The group was first examined between 1971 and 1975 and then followed up in 1982-1984, 1986, 1987 and 1992. Men who reported low levels of nonrecreational physical activity had increased risk of prostate cancer compared with very active men. These findings were stronger for African-Americans. Lower levels of recreational activity were weakly associated with increased prostate cancer risk among African-Americans hut not among Caucasians. These results suggest that inactive men are at increased risk of prostate cancer.

CANCER EPIDEMIOLOGY BIOMARKERS & PREVENTION, 2000, Vol 9, Iss 9, pp 875-881


10. Raloxifene vs. tamoxifen on lipid metabolism

Tamoxifen and raloxifene, selective estrogen receptor modulators, decrease concentrations of total cholesterol in the blood. A study looked at the effect of raloxifene on lipid metabolism compared with tamoxifen. Liver intracellular concentrations of total cholesterol and triglyceride without oleic acid or very low density lipoprotein (VLDL) were not significantly different after treatment with tamoxifen or raloxifene. In contrast, although raloxifene with oleic acid did not increase the intracellular concentrations of triglyceride, tamoxifen treatment in the presence of oleic acid or VLDL significantly increased the triglyceride concentrations. This suggests that raloxifene does not increase intracellular triglyceride in the presence of oleic acid or very low density lipoprotein, in contrast to tamoxifen. Therefore, raloxifene might be safer than tamoxifen for treating unstable triglyceride levels or a history of hypertriglyceridemia (excess of triglycerides in the blood).

EUROPEAN JOURNAL OF ENDOCRINOLOGY, 2000, Vol 143, Iss 3, pp 427-430



Back to the Magazine Forum