- Human longevity at the cost of reproductive success
Full source: Nature, 1998, Vol 396, Iss 6713, pp 743-746 The disposable soma theory on the evolution of aging states that longevity requires investments in somatic maintenance that reduce the resources available for reproduction. Experiments with the fruit fly (Drosophila melanogaster) indicate that trade-offs of this kind exist in non-human species. This study determined the interrelationship between longevity and reproductive success in humans using historical data from the British aristocracy. The number of progeny was small when women died at an early age, increased with the age of death, reaching a plateau through the sixth, seventh and eighth decades of life, but decreased again in women who died at an age of 80 years or over. Age at first childbirth was lowest in women who died early and highest for women who died at the oldest ages. When account was taken only of women who had reached menopause, who were aged 60 years and over, female longevity was oppositely associated with number of progeny and positively associated with age at first childbirth. The findings show that human life histories involve a trade-off between longevity and reproduction.
- Antioxidant supplementation reverses age-related neuronal changes
Full source: Neurobiology of Aging, 1998, Vol 19, Iss 5, pp 461-467 Evidence suggests that free radicals in the brain may play a role in the development of age-related neuronal impairments. The increase in the concentration of the proinflammatory cytokine (cells which regulate immune responses), interleukin-1 beta (can cause fever, induce synthesis of acute phase proteins, and initiate metabolic wasting), in aged brain tissue, may also be a contributory factor. This study analyzed changes in enzymatic and nonenzymatic antioxidant levels, in parallel with interleukin-1 beta concentration, in cortical brain tissue prepared from young and aged rats. Results showed an age-related increase in the activity of superoxide dismutase and an age-related decrease in the concentrations of vitamin E and C. These observations, coupled with age-related increases in lipid peroxidation and interleukin-1 beta concentration show a compromised antioxidant defense in cortex of aged rats. These negative changes were not observed in cortical tissue prepared from rats fed on a diet supplemented with vitamin E and C for 12 weeks.
- IGF-1 blocks the aging-related loss of skeletal muscle function
Full source: Proceedings of the National Academy of Sciences of the United States of America, 1998, Vol 95, Iss 26, pp 15603-15607 During the aging process, mammals lose up to a third of their skeletal muscle mass and strength. This study attempted to reduce the loss by increasing the regenerative capacity of muscle. This involved the injection of a virus causing an increase of insulin-like growth factor I (IGF-I) in muscle fibers. Results showed that the IGF-I increase promotes an average increase of 15% in muscle mass and a 14% increase in strength in young adult mice, and remarkably, prevents aging-related muscle changes in old adult mice, resulting in a 27% increase in strength as compared with uninjected old muscles. Muscle mass and fiber type distributions were maintained at levels similar to those in young adults. According to researchers, these effects are primarily due to stimulation of muscle regeneration via the activation of satellite cells by IGF-I. This supports the hypothesis that the primary cause of aging-related impairment of muscle function is a cumulative failure to repair damage sustained during muscle utilization. These results suggest that gene transfer of IGF-I into muscle could form the basis of a human gene therapy for preventing the loss of muscle function associated with aging and may be of benefit in diseases where the rate of damage to skeletal muscle is accelerated.
- Safflower oil vs. perilla oil on lipid metabolism
Full source: Comparative Biochemistry and Physiology B - Biochemistry & Molecular Biology, 1998, Vol 121, Iss 2, pp 223-231 Diets high in linoleic acid (20% safflower oil contained 77.3% linoleic acid, SO-diet) and a-linolenic acid (20% perilla oil contained 58.4% alpha-linolenic acid, PO-diet) were fed to rats for 3, 7, 20, and 50 days, and effects of the diets on lipid metabolism were compared. Levels of serum total cholesterol and phospholipids in the rats fed the PO-diet were markedly lower than those fed the SO-diet after the seventh day. In blood and liver phosphatidylcholine, the proportion of n-3 fatty acids showed a greater increase in the PO group than in the SO group. The results indicate that alpha-linolenic acid (perilla oil) has a more potent serum cholesterol-lowering ability than linoleic acid (safflower oil) both in short and long feeding terms.
- Estrogen therapy in preventing and slowing the progression of dementia
Full source: Controlled Clinical Trials, 1998, Vol 19, Iss 6, pp 604-621 Evidence from animal, human cross-sectional, case-control, and prospective studies indicate that hormone replacement therapy (HRT) is a promising treatment to delay the onset of symptoms of dementia. The Women's Health initiative Memory Study (WHIMS) is the first double-masked, randomized, placebo-controlled, long-term clinical trial designed to test the hypothesis that HRT reduces the incidence of all-cause dementia in women aged 65 and older. WHIMS, an ancillary study to the Women's Health Initiative (WHI) funded by the National Institutes of Health, will recruit a subgroup of women aged 65 and older from among those enrolling in the HRT trial of the WHI. The WHI clinical centers and 10 affiliated satellites plan to enroll approximately 8300 women into WHIMS over a 2-year period. Participants will be followed annually for 6 years, receiving cognitive assessments via the Modified Mini-Mental State (3MS) Examination. Women who screen positively for cognitive impairment on the basis of an educational and age-adjusted 3MS cutpoint proceed to more extensive neuropsychological testing and neurologic evaluation. Each woman suspected to have dementia then undergoes a series of laboratory tests that confirm the clinical diagnosis and classify the type of dementia. WHIMS is designed to provide more than 80% statistical power to detect a 40% reduction in the rate of all-cause dementia, an effect that could have profound public health implications for older women's health and functioning.
- Chronic pancreatitis and antioxidant therapy
Full source: Digestion, 1998, Vol 59, Suppl. 4, pp 36-48 According to The Manchester 'oxidant stress' hypothesis for the development of pancreatitis, oxidant stress, mainly from reactive foreign substances, are perceived as the key cause of disease in chronic pancreatitis, and by depleting glutathione, targets the exocytosis mechanism (process whereby cell membrane ruptures) of the pancreatic acinar cell. Inhalation exposure to petrochemical products is identified as an independent risk factor in patients at Manchester Royal Infirmary, where some 50% of patients referred have non-alcoholic disease. This paper describes the development of antioxidant therapy, using supplements of methionine, vitamin C and selenium, and its validation in a placebo-controlled trial, followed by a retrospective cross-sectional study in 94 consecutive patients for an average of 30 months. Antioxidant therapy emerges as a safe and effective medical alternative to surgery for painful chronic pancreatitis.
- Osteoporosis in men-prevention and management
Full source: Drugs & Aging, 1998, Vol 13, Iss 6, pp 421-434 Osteoporosis is increasingly recognized in men. Low bone mass, risk factors for falling and factors causing fractures in women are likely to cause fractures in men. Bone mass is largely genetically determined, but environmental factors also contribute. Greater muscle strength and physical activity are associated with higher bone mass, while radial bone loss is greater in cigarette smokers or those with a moderate alcohol intake. Sex hormones have important effects on bone physiology, In men, there is no abrupt cessation of testicular function or 'andropause' comparable with the menopause in women; however, both total and free testosterone levels decline with age. A common secondary cause of osteoporosis in men is hypogonadism. There is increasing evidence that estrogens are important in skeletal maintenance in men as well as women. Conversion of androgens to estrogens occurs. Human models exist for the effects of estrogens on the male skeleton. In men over 65, there is a positive association between bone mineral density (BMD) and greater serum estradiol levels at all skeletal sites and a negative association between BMD and testosterone at some sites. It is important to exclude pathological causes of osteoporosis here because 30 to 60% of men with vertebral fractures have another illness contributing to bone disease. Glucocorticoid (steroids) excess (mostly originating outside the body) is common. Gastrointestinal disease makes patients susceptible to bone disease as a result of intestinal malabsorption of calcium and vitamin D. Hypercalciuria and nephrolithiasis, anticonvulsant drug use, thyrotoxicosis, immobilization, liver and renal disease, multiple myeloma and systemic mastocytosis have all been associated with osteoporosis in men. It is possible that low-dose estrogen therapy or specific estrogen receptor-modulating drugs might increase BMD in men as well as in women. In the future, parathyroid hormones may be an effective treatment for osteoporosis, particularly in patients in whom other treatments, such as bisphosphonates, have failed. Men with osteoporosis of unknown origin have low circulating insulin-like growth factor-1 (IGF-1, somatomedin-l) concentrations, and IGF-1 administration. Studies of changes in BMD with IGF-I treatment in osteoporotic men and women are underway. Osteoporosis in men will become an increasing worldwide public health problem over the next 20 years, so it is vital that safe and effective therapies for this disabling condition become available.
- GH deficiency: Signs, symptoms, and diagnosis
Full source: Endocrinologist, 1998, Vol 8, Iss 6, Suppl. 1, pp 8S-14S The use of growth hormone (GH) for children with growth hormone deficiency (CHD) is well established. However, GHD is a syndrome that affects patients of all ages. Literature on pediatric GHD is extensive because treatment of this condition with GH replacement was approved about 12 years ago. Although GH-replacement therapy for adult GHD has been accepted practice in Europe for nearly 15 years, it was approved only recently for this indication in the United States. In adults, GHD has nonspecific symptoms, such as fatigue and impaired psychointellectual capacities, or no symptoms. Measurable alterations induced by GHD in adults may include altered body composition, reduced bone mineral density, impaired physical performance, abnormal lipid metabolism, and impaired quality of life. GHD is common in patients with treated or untreated pituitary tumors or other disorders of the pituitary, patients who have had cranial irradiation, and adults with a history of childhood-onset GHD. Isolated low levels of insulin-like growth factor-1 (IGF-1) may indicate GHD but cannot substitute for a testing process wherein there is an inadequate response of blood GH to insulin induced hypoglycemia.
- Curcumin and cell membrane dynamics
Full source: Experimental Cell Research, 1998, Vol 245, Iss 2, pp 303-312 Curcumin is a well-known natural compound with anti-inflammatory properties. Its antiproliferative effect and ability to modulate apoptosis (programmed cell death) are considered essential in cancer therapy. Due to the properties of curcumin, it targets local membranes. This prompted an investigation of the mechanisms of membrane changes evoked by curcumin. Curcumin was found to expand the cell membrane, inducing echinocytosis (overabundance of prickly cells). Changes in cell shape were accompanied by transient exposure of phosphatidylserine. Membrane disproportion was recovered by the action of an enzyme, which remained active in the presence of curcumin. Lipids rearrangements and drug partitioning caused changes of lipid fluidity. Based on these results, curcumin would produce various incidents of beneficial apoptosis.
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