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Biomedical subjects

J S Grigsby

Publications and source records attributed to J S Grigsby.

6 recordsLinked to original sources
PubMed1996

Aging and heterogeneity: genetics, social structure, and personality.

Life-course studies of human development suggest that birth cohorts become more internally differentiated with respect to personality characteristics as their members age. This article examines possible explanations for this macro-level phenomenon in terms of three micro-level research traditions: (1) individual differentiation, (2) social structure/allocation, and (3) behavioral genetics. We conclude that each tradition can marshal credible empirical support, and that, therefore, all three are needed for a full understanding of older-age heterogeneity processes. A model is developed, synthesizing all three approaches. Study designs in any one of these traditions that fail to take account of the others are likely to draw misleading or erroneous conclusions concerning sources of variation and covariation. Several types of study designs are suggested which would avoid such problems.

Aged↗
PubMed1991

Paths for future population aging.

Developed countries with low fertility and mortality rates are already experiencing population aging and will continue to do so. Some developing countries undergoing demographic transitions are beginning to acknowledge the issues of population aging. The projected declines in fertility in other developing countries will mean substantial population aging in the future. Alternative measures for population aging can clarify issues that arise with this process. Because population aging is inevitable, all countries need to incorporate aging policies with population policies.

Adolescent↗
PubMed1976

The effect of testosterone on skeletal muscle development and protein synthesis in rabbits.

The effect of testosterone administration on muscle development and protein synthesis was studied with intact male rabbits. Rabbits were randomized into three experimental groups; day 0 control (G-1), day 15 control (G-2) and day 15 testosterone (G-3). Testosterone (delta4-Androsten-17beta-ol-3-one in silastic tubing) was surgically implanted into the G-3 rabbits. On day (G-1) and day 15 (G-2 and 3) of the experiment all rabbits were injected IP with 50 mu Ci-3H-leucine. Rabbits were sacrificed at intervals after the 3H-leucine injection. Right and left semitendinosus muscles, pituitary and adrenal glands, testicles and blood samples were obtained for analysis. Testosterone improved (P less than .01) gain and feed efficiency, depressed testicle weight (P less than .01), increased serum testosterone and insulin (P less than 0.01) but did not affect adrenal and pituitary weights. Muscle moisture, fat and total protein, myofibrillar, sarcoplasmic and stromal protein fractions and RNA and DNA content were not significantly affected by testosterone although G-3 semitendinosus muscle had the highest total and myofibrillar protein, RNA, and DNA content. The testosterone treated rabbits (G-3) had higher (P less than 0.05) 3H-leucine incorporation into myofibrillar protein and lower 3H-leucine incorporation into sarcoplasmic protein than the day 0 and day 15 controls.

Adrenal Glands↗