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Biomedical subjects

D E Davis

Publications and source records attributed to D E Davis.

10 recordsLinked to original sources
PubMed1991

Seasonal change in irradiance: a zeitgeber for circannual rhythms in ground squirrels.

1. Zeitgebers for circannual rhythms have been elusive. Demonstration that an external factor is a zeitgeber requires proof of a phase-shift that endures for several years. 2. The California ground squirrel (Spermophilus beecheyi) is an ideal subject. Many features of behavior have circannual rhythms of which change in mass is the easiest to measure. The squirrels thrive in captivity for up to 10 years. The squirrels were kept in individual cages in an air conditioned room, fed lab chow ad lib, and weighed twice a month. They were exposed to a 6-month phase shift of (a) length of day (b) seasonal change in temperature, (c) both, (d) seasonal cycle of irradiance. 3. The squirrels maintained circannual rhythms for up to 9 years. Entrainment was evident only by squirrels exposed to seasonal change in irradiance.

Animals↗
PubMed1988

Septic arthritis due to gram negative bacilli: older patients with good outcome.

Previous studies of gram negative bacillary septic arthritis conclude it is an uncommon disease of older patients with poor outcome, or of younger patients with good outcome. We reviewed 22 cases of gram negative bacillary septic arthritis in a rural population. The mean age was 61 years, symptoms were of short duration (6.5 days mean), and a chronic illness was frequently present (77%). The knee was involved in 73% and E. coli was the usual causative organism (32%). Antibiotics plus aspiration was a successful initial therapy. Overall survival was 95% and a good outcome was achieved in 68%. Gram negative bacillary septic arthritis affects older patients, and the outcome appears good.

Aged↗
PubMed1987

Cricoarytenoid arthritis: a cause of laryngeal obstruction.

Cricoarytenoid arthritis, principally as a result of long-standing rheumatoid arthritis, is a disorder that may present to the emergency physician with a number of symptoms and signs referable to the larynx. The presentation of this disorder as acute laryngeal obstruction and collapse is uncommon. It is important to recognize early cricoarytenoid joint involvement and not mistakenly diagnose mild cases as asthma or psychoneurosis. The use of steroids in mild cases has been beneficial at times, but progressive airway obstruction and fatalities have occurred during their administration.

Arthritis, Rheumatoid↗
PubMed1986

Tuberculosis of peripheral joints: an often missed diagnosis.

Eleven elderly patients with tuberculous arthritis of 12 peripheral joints were studied retrospectively. The disease usually presented as a monoarticular arthritis often in the absence of other signs of tuberculosis. A delay in diagnosis was a common feature and synovial biopsies provided the highest diagnostic yield.

Aged↗
PubMed1976

Hibernation and circannual rhythms of food consumption in marmots and ground squirrels.

In order to understand better the evolution and adaptive value of hibernation, ecological aspects and experimental studies of closely related hibernators, the Marmotini, are examined. The central hypothesis is that annual changes in the environment integrate three or, perhaps, four physiological processes: torpor, reporduction, consumption of food, and metabolism. Reproduction occurs promptly after emergence from hibernation. For most species, the breeding season is very short. Although the experimental data are rather meager, no variation in external factors has consistently altered the season of reproduction. Consumption of food and change in weight increases until July or September and then decreases. The large members of the Marmotini store their energy as fat, but small species store their energy as seeds and nuts. Experiments to test the hypothesis that some aspect of the supply, such as fat content, might vary seasonally have produced negative results. Complex experiments on the length of the photoperiod on woodchucks and several species of ground squirrels failed to alter the annual cycle of consumption of food. Animals kept in constant conditions showed a cycle of about 11 months, but woodchucks sent tto Australia changed their cycle in two years to match the seasons of the southern hemisphere. Experiments with temperature and torpor and castration did not alter the annual did not alter the rhythm...

Adipose Tissue↗