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LE Magazine January 1999

MEDICAL UPDATES

Studies from throughout the world that can help you live longer

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January 1999
Table Of Contents

 


Dietary soy and hot flashes

Fifty-one patients (age range 48-61 years) took 60 grams of isolated soy protein daily. The changes of moderate-to-severe hot flashes (including night sweats) during treatment was analyzed. Soy was significantly superior to the placebo in the number of hot flashes per 24 hours after 4, 8, and 12 weeks of treatment. There was a 26% reduction in the mean number of hot flashes by week 3 and a 33% reduction by week 4. By the end of the 12th week, there was 45% reduction in daily hot flashes versus a 30% reduction obtained with the placebo. The overall rates of adverse effects were similar for soy and the casein-placebo. Thus, soy protein isolate, added daily to the diet, substantially reduced the frequency of hot flashes in climacteric (menopausal) women.

Obstetrics and Gynecology, 1998, Vol 91, Iss 1, pp 6-11



Ginkgo, cognition and longevity

Extracts of the leaves of the Ginkgo biloba tree are widely used throughout the world for their purportedly beneficial effects on brain function. A precession administration of ginkgo extract at a dose of 50 mg/kg in rats resulted in a trend toward fewer test sessions to reach criterion performance, as well as fewer errors. In addition, it was observed that rats chronically treated with the extract lived significantly longer than control subjects. Ginkgo administered prior to maze testing produced a dose-related decrease in total, retroactive, and proactive errors in 20-month-old rats. Following the dose-response determination, half the group at 26 months of age received ginkgo at a dose of 200 mg/kg precession and the other half sweetened condensed milk. A statistically significant positive effect of treatment with ginkgo was observed. The present data are consistent with the beneficial effects on cognitive performance which have been widely reported in human subjects. The results encourage a search for the pharmacologically active principles of ginkgo extract and for their mechanisms of action.

Physiology & Behavior, 1998, Vol 63, Iss 3, pp 425-433



Vitamins C and E versus sunburn

UV radiation causes acute adverse effects such as sunburn, photosensitivity reactions, or immunologic suppression, as well as long-term photo-aging or malignant skin tumors. UV radiation induces tissues to produce free radicals, eicosanoids and cytokines (proteins secreted by cells, which regulate the intensity and duration of immune responses). Inhibition of these mediators might reduce skin damage. Antioxidants such as vitamins C and E have been found to be photo-protective in some in-vitro studies and animal experiments. Ten subjects took either 2 grams of vitamin C combined with 1,000 IU of vitamin E, or a placebo every day. The sunburn reaction before and after 8 days of treatment was assessed by determination of the threshold UV dose (toleration of exposure) for eliciting sunburn, and by measuring the blood flow of skin irradiated with incremental UV doses against that of nonirradiated skin. The threshold of sunburn increased from 80 to 96.5 mJ/cm, whereas it declined from 80 to 68.5 mJ/cm in the placebo group. Cutaneous blood flow decreased in those given vitamins and increased in the placebo group. Combined vitamins C and E reduce the sunburn reaction, which might indicate a consequent reduced risk for later conditions due to UV-induced skin damage.

Journal of the American Academy of Dermatology, 1998, Vol 38, Iss 1, pp 45-48



Silymarin protects the pancreas

Silymarin can be extracted from the milk thistle, and silibinin is the main component of the plant extract. Possibly due to their antioxidant and membrane-stabilizing properties, the compounds have been shown to protect different organs and cells against a number of injuries. Thus liver, kidney, erythrocytes and platelets have been protected from the toxic effects of alcohol, carbon tetrachloride, cold ischemia and drugs. This study investigated whether silibinin treatment weakens cyclosporin A (CiA, an immunosuppressant, used to inhibit organ transplant rejection) toxicity on rat endocrine and exocrine pancreas. After 9 days treatment with CiA and/or silibinin, blood glucose levels were significantly higher in rats treated with CiA, while silibinin did not affect glucose levels. Insulin secretion was inhibited after treatment with silibinin, but amylase secretion was not affected. After treatment with CiA, both insulin and amylase secretion were reduced. Silibinin and CiA had an additive inhibitory effect on insulin secretion, but silibinin weakened CiA-induced inhibition of amylase secretion. Despite CiA treatment, amylase secretion was in fact restored to normal with the highest dose of silibinin. These data show that silibinin inhibits glucose-stimulated insulin release in-vitro, while not affecting blood glucose concentration in-vivo. This combination of effects could be useful in the treatment of non-insulin-dependent diabetes mellitus. In addition, silibinin protects the exocrine pancreas from CiA toxicity. Since this inhibitory effect is unspecific, silibinin may also protect the exocrine pancreas against other insult principles, such as alcohol.

Cellular and Molecular Life Sciences, 1997, Vol 53, Iss 11-12, pp 917-920



Vitamin C and impaired vitamin E retention

Guinea pigs were fed 15% oxidized frying oil (OFO) diets supplemented with vitamin C at 300, 600 or 1,500 mg/kg diet. Control animals were fed a diet containing 15% fresh untreated soybean oil with 300 mg/kg of vitamin C. After 60 days, plasma cholesterol concentration was highest in guinea pigs fed the OFO diet supplemented with 300 mg/kg vitamin C. Increasing vitamin C in OFO diets significantly reduced plasma cholesterol concentration. Plasma and tissue vitamins C and E concentrations were significantly lower in the OFO-fed guinea pigs receiving only 300 mg/kg vitamin C than in controls. Greater levels of supplemental vitamin C increased tissue vitamins C and E. Guinea pigs fed OFO diets also had significantly higher tissue levels of free radicals than controls. The results show that OFO feeding, which impaired vitamin E retention and increased tissue levels of free radicals, could be alleviated somewhat by vitamin C supplementation. Journal of Nutrition, 1998, Vol 128, Iss 1, pp 116-122



Thymic aging and T-cell regeneration

Studies of T-cell regeneration using animal models have consistently shown the importance of the thymus for T-cell regeneration. In humans, recent studies have shown that declines in thymic T-cell regenerative capacity begins relatively early in life, resulting in a limited capacity for T-cell regeneration by young adulthood. The limitations in T-cell regeneration have significant clinical implications in the setting of HIV infection and bone marrow transplantation and may also contribute to immunologic abnormalities associated with normal aging. The mechanisms responsible for thymic aging are not well-understood. Current evidence suggests that changes within the thymus itself are primary, while age-related changes in bone marrow T-cell precursors contribute to a lesser extent. The development of therapies which can reverse thymic aging are critical for improving outcome in clinical settings of T-cell depletion, and could potentially improve immunologic function in normal aged hosts.

Immunological Reviews, 1997, Vol 160, pp 91-102



Exogenous testosterone and the prostate

A total of 31 healthy volunteers 21 to 39 years old were randomized to receive either 100, 250 or 500 mg testosterone via intramuscular injection once a week for 15 weeks. Baseline measurements of serum testosterone, free testosterone and prostate specific antigen (PSA) were taken at week 1. Semen samples were also collected for PSA content, and prostate volumes were determined by transrectal ultrasound before testosterone injection. Blood was then drawn every other week before each testosterone injection for the 15 weeks, every other week thereafter until week 28, and again at week 40. After the first 15 weeks, semen samples were again collected, and prostate volumes were determined by repeat transrectal ultrasound. Free and total serum testosterone levels increased significantly in the 250- and 500-mg dose groups. No significant change occurred in the prostate volume or serum PSA levels at any dose of exogenous testosterone. Total semen PSA levels decreased following administration of testosterone but did not reach statistical significance. Thus, despite significant elevations in serum total and free testosterone, healthy young men do not demonstrate increased serum or semen PSA levels, or increased prostate volume, in response to exogenous testosterone injections.

Journal of Urology, 1998, Vol 159, Iss 2, pp 441-443



Flavonoids and cancer risk

The relation between the intake of antioxidant flavonoids and a subsequent risk of cancer was studied among 9,959 Finnish men and women aged 15 to 99 years who were initially cancer-free. Food consumption covering the previous year was estimated by the dietary history method. During a follow-up from 1967 to 1991, 997 cancer cases and 151 lung cancer cases were diagnosed. An inverse association was observed between the intake of flavonoids and incidence of all sites of cancer combined. The associationwas strongest in persons under 50 years of age. Of the major dietary flavonoid sources, the consumption of apples showed an inverse association with lung cancer incidence. The results are in line with the hypothesis that flavonoid intake in some circumstances may be involved in the cancer process, resulting in lowered risks. American Journal of Epidemiology, 1997, Vol 146, Iss 3, pp 223-230



Deprenyl and the brain

L-deprenyl (selegiline) was administered to rats beginning at 54 weeks of age (the estimated daily dose was 0.5 mg/kg/day). Beginning at 84 weeks of age, the rats were behaviorally evaluated using a sensorimotor battery, a motor-learning task, and the Morris water maze. At 118 weeks of age, cerebellar noradrenergic function was evaluated in the surviving rats using in-vivo electrochemistry. Brain monoamine oxidase activity was measured. The effects of ongoing deprenyl treatment on beta-adrenergic receptors in the cerebellum, adrenergic receptors in several brain regions, and dopamine receptors in the striatum were evaluated. Deprenyl treatment reduced brain monoamine oxidase B activity by 85%.

Also, several measures of central nervous system function were altered in the deprenyl-treated animals: 1) Spatial learning was improved; 2) the responsiveness to the reuptake blocker nomifensine (antidepressant) was enhanced in the cerebellum; 3) beta-adrenergic receptor binding affinity was increased in the cerebellum; 4) adrenergic receptor density was increased; and 5) dopamine receptor density was reduced, but binding affinity was enhanced. In contrast, chronic deprenyl treatment did not cause changes in sensorimotor function, as evaluated by balance beam, inclined screen, or wire hang tasks and motor learning. Thus, long-term oral administration of deprenyl extended the functional life span of rats with respect to cognitive, but not motor, performance.

Neurobiology of Aging, 1997, Vol 18, Iss 3, pp 309-318



Vitamin B6, C in the elderly

This study evaluated whether vitamin B6 and vitamin C metabolism may be altered by infection in the elderly. Eighteen subjects greater than or equal to 75 years were divided into 3 groups: Acute infection, malnourished, and control subjects. During the 3 weeks, vitamin B6 values were significantly higher in group III than in both groups I and II. Vitamin C values were significantly lower in group I than in both groups II and III. The data suggest that an acute catabolic state like infection may influence vitamin B6 and vitamin C metabolism.

Annals of Nutrition and Metabolism, 1997, Vol 41, Iss 6, pp 344-352



Red grape juice as antioxidant

This study examined whether the beneficial antioxidant effects of red wine can be reproduced by nonalcoholic red grape juice concentrate. Seven subjects consumed 125 mL red grape juice concentrate daily for 7 days. There was a rise in serum total antioxidant capacity from 441 to 478 mu mol/L at 60 minutes. On day 8, total antioxidant capacity was 50 mu mol/L higher than at the start. There was reduced susceptibility of low-density lipoprotein (LDL) to oxidation. Red grape juice concentrate ingestion results in increased serum antioxidant capacity and protection of LDL from oxidation. Thus nonalcoholic red grape extract may have similar beneficial effects to red wine.

Annals of Nutrition and Metabolism, 1997, Vol 41, Iss 6, pp 353-357

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