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Biomedical subjects

A E Miller

Publications and source records attributed to A E Miller.

At least 55 records · Page 3Linked to original sources
PubMed1978

Hypothalamic LH-releasing activity in young and aged intact and gonadectomized rats.

Hypothalamic LH-releasing activity content was measured in young (3-5 mo) and aged (22-26 mo) intact and gonadectomized male and female rats. Hypothalamic extracts (0.25, 0.5 and 1.0 hypothalamus equivalents) from young and aged rats were incubated with untreated hemisectioned rat pituitaries in medium 199. All hypothalamic extract treatments stimulated LH release from the incubated pituitaries. Increased amounts of hypothalamic extracts added to to the incubation medium proportionally increased LH release. There were no differences in LH release stimulated by young or aged hypothalamic extracts from either the intact or gonadectomized groups. In addition serum testosterone concentrations were reduced in the aged male rats and serum LH was lower in aged male and female rats than in the young groups. Although serum LH was increased after gonadectomy in all groups, the increase was of smaller magnitude in the aged rats. These data indicate significant alterations in the responsiveness of the hypothalamus to steroid feedback in the aged rat. Although the hypothalamus contains sufficient LH-releasing activity to stimulate higher levels of pituitary and gonadal endocrine function, aging effects on the neuroendocrine control mechanisms inhibit hypothalamic hormone function.

Aging↗
PubMed1978

Serum testosterone and testicular response to HCG in young and aged male rats.

Serum testosterone and testicular response to HCG was measured in young (3 - 6 mo) and aged (20 - 30 mo) male Long-Evans rats. Serum testosterone was measured by radioimmunoassays on serial blood samples taken before and after injections of HCG. Control group serum testosterone concentrations were lower in aged compared to young groups. Intravenous injection of 1, 5, and 20 IU of HCG increased serum testosterone in both age groups and testosterone remained elevated throughout the 150-min sampling interval. The increase in serum testosterone concentrations following acute HCG stimulation was greater in young than in aged rats. Serum testosterone concentrations and testicular response to intravenous HCG injections were increased to similar levels in young and aged male rats following 7 days of daily subcutaneous injections of 5 IU of HCG/100 gm bw. These data suggest that while testicular secretion and responsiveness is reduced with age, the aged male rat retains the capacity to secrete more testosterone than it normally maintains.

Aging↗
PubMed1978

The changing urban-suburban distribution of medical practice in large American metropolitan areas.

The twenty largest multi-county SMSAs in the U. S. were studied for trends in the suburbanization of medical practice from 1959 to 1974. Fifteen of them allowed a distinction between suburbs and central city on the county level according to criteria developed from a New York City pilot study. In all SMSAs, the density of hospital-based physicians was higher in central cities than in suburbs and still increasing more rapidly there, though hospital practice is also starting to grow in the suburbs at an appreciable rate. The same trends were found for physicians in non-patient care activities. Office based specialists in large Northeastern SMSAs increased much more rapidly in the urbanized suburbs than in the central cities. In the Southern and Western SMSAs, on the contrary, office-based specialists continued to increase rapidly in the central cities despite concentrations already far greater than in the Northeast. Suburban desities were growing more slowly in these areas. General practitioners declined uniformly everywhere, apparently simply by attrition. Implications of these trends for health care are discussed.

Family Practice↗
PubMed1977

Effect of aging on hypothalamic LH-releasing and prolactin inhibiting activities and pituitary responsiveness to LHRH in the male laboratory rat.

Hypothalamic content of LH releasing and prolactin inhibiting activities and pituitary responsiveness to LH releasing hormone was measured in young (4 mo.) and aged (26 mo.) Long-Evans rats by in vitro methods. Hypothalamic extracts (0.5 and 1.0 hypothalamic equivalents) from young and aged male rats were incubated with untreated hemisected rat pituitaries in medium 199. Doses of 0.5 and 1.0 hypothalamic equivalents (HE) from both age group stimulated LH secretion. The increase in pituitary LH release stimulated by 0.5 HE from aged male rats was about half that stimulated by 0.5 HE from the young male group (p less than .20). The increase in LH secretion stimulated by hypothalamic extracts of either age group was not associated with a change in pituitary LH content. Although 0.5 and 1.0 HE from young male rats and 1.0 HE from the aged group reduced incubated pituitary prolactin release, 0.5 HE from the aged males did not affect prolactin release. Treatment with hypothalamic extracts also resulted in increased pituitary prolactin concentrations. Pituitaries from young and aged male rats were incubated in medium 199 containing 0, 25, or 100 ng of LH releasing hormone. Although LH releasing hormone stimulated LH secretion in all groups, the increase in release of LH was less in the aged groups than from pituitaries from the young male rats. Pituitary LH content of the aged male group was only about 1/4 that of the young group.

Aging↗
PubMed1976

Aging effects on hypothalamic dopamine and norepinephrine content in the male rat.

Hypothalamic content of dopamine and norepinephrine was measured in young (4 mo) and aged (24-26 mo) male rats by aluminum oxide adsorption and microfluorescence. Hypothalamic content of both dopamine and norepinephrine was significantly less in aged than in the young groups. Average dopamine content of the young and aged groups was 32.5 +/- 9.3 and 15.6 +/- 2.5 ng/hypothalamus, respectively. Norepinephrine content averaged 47.6 +/- 10.7 and 22.8 +/- 1.8 ng/hypothalamus in the young and aged groups. These data suggested that alterations in hypothalamic catecholamine function contribute to changes in endocrine control mechanisms during aging.

Aging↗
PubMed1975

Lessons from the Chinese experience: China's planned birth program and its transferability.

This article describes the most salient developments in the planned birth program of the People's Republic of China during the 1970s and discusses the potential for transfer of some features to other countries. Many Chinese activities are of interest because they are designed for a country with scarce resources for development and a low-income population. Some particular program features worth noting are: the encouragement of local initiative and experimentation: specific methods for the diffusion of innovation; and total integration of the health system with other development-political, administrative, economic, and social-at the grass-roots level.

Birth Rate↗
PubMed1973

Lymphocyte transformation during dinitrochlorobenzene contact sensitization. An in vitro and in vivo evaluation of the primary immune response in man.

An evaluation of cell-mediated immunity in man is described that combines the advantages of an in vitro technique, lymphocyte transformation, with the use of contact sensitization to a primary immunogen, dinitrochlorobenzene (DNCB). DNCB, when coupled to autologous or allogeneic peripheral blood leukocytes, forms a complex, DNCB-antigen, that induces lymphocyte transformation specifically in leukocyte cultures from subjects sensitized to DNCB. Sequential studies of lymphocyte transformation to DNCB-antigen show that specifically reactive lymphocytes are first detected at about 10 days after in vivo application of a sensitizing dose of DNCB and reach a peak at about 14-21 days.

Adult↗