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Biomedical subjects

I Leav

Publications and source records attributed to I Leav.

66 records · Page 4Linked to original sources
PubMed1977

An anesthetized dog heatstroke model.

This study was undertaken to develop an anesthetized dog heatstroke model. Forty-six animals were anesthetized with pentobarbital sodium (25 mg/kg) intravenously, and maintained at an ambient temperature of (42-46 degrees C) with a water-heated blanket over 2.5-3.0 h until rectal temperatures rose to 43.0-44.5 degrees C. Animals then cooled passively until death occurred or until 18 h elapsed, and were prepared for autopsy. Liver, kidney, and brain temperature, mean weighted skin temperature, mean weighted surface heat loss, and metabolic rates were obtained. There were no significant differences between liver, kidney, brain, and rectal temperatures during the heating and cooling periods. Cardiac output rose to 127% of initial value, and dropped rapidly to zero at 43.4 degrees C rectal temperature. The rapid decline was accompanied by a doubling of heart rate and a rapid drop in blood pressure and respiratory rate. Cheyne-Stokes respiration and apnea preceded bradycardia followed by asystole or ventricular fibrillation. Certain serum constituents demonstrated modest elevations suggestive of widespread tissue damage. Autopsy did not reveal a clear pattern of heat injury, with the exception of consistent congestion of the major organs and karyorrhexis of lymphocytes. These data are in agreement with similar data from human heatstroke victims and other heatstroke modeling in dogs, and support the concept that the anesthetized dog can in many respects provide an adequate model for human heatstroke.

Anesthesia, Intravenous↗
PubMed1977

Thyrotropin stimulation of 32P incorporation into the phospholipids of canine thyroid adenocarcinoma.

Six carcinomas of the canine thyroid were studied. Five of the six tumors were functional on 131I scan and caused hyperthyroidism in two cases. The tumors were all of predominantly compact cellular histology with rare to moderate numbers of microfollicles. After surgical removal tumor slices were incubated with 32P in Krebs-Ringer-tris buffer with or without 0.1 U/ml of bovine TSH, and the specific activity of the extracted phospholipids was measured. TSH stimulated phosphatide turnover clearly in 5 cases and probably also in the 6th. Analysis of fractionated phospholipids in 2 cases showed that the response to TSH was mainly in the phosphatidic acid and phosphatidylinositol. These studies show that a malignant tumor may still retain at least one complete control system extending from TSH receptors to the final metabolic response.

Adenocarcinoma↗
PubMed1976

The laboratory rat as a model for hyperthermic syndromes in humans.

To assess the lethal effects of work-induced hyperthermia on exercising animals, untrained rats were run to exhaustion at 5 and 20-26 degrees C or restrained at 41.5 degrees C. An exercise-induced core temperature of 40.4 degrees C represented a base line above which mortalities occurred. With increasing core temperature at exhaustion (between 40.4 and 43 degrees C), mortality increased within 24 h. A dose-respones curve with an LD50 equivalent to a core temperature of 41.5 +/- 0.1 degrees C was calculated. Although differences in body weight loss, core temperature at exhaustion, and cooling rate will clearly distinguish between survivors and fatalities, the severity of heat injury as inferred from survival times is best measured by the time versus intensity of hyperthermia in degree-minutes.

Acclimatization↗
PubMed1975

Distinctive intestinal mast cell neoplasms of domestic cats.

By use of histologic, histochemical, and ultrastructural techniques a group of distinctive intestinal neoplasms of domestic cats, previously thought to arise from enterochromaffin cells, were redefined as mast cell neoplasms. Although these tumors differed histologically from the more typical visceral mast cell neoplasm of cats, ultrastructural and histochemical similarities between cells comprising both tumors were encountered. Differences in granule morphology and histochemical characteristics were, however, consistently demonstrated when the neoplasms were compared. The intestinal neoplasms are not associated with ulceration of the gastrointestinal tract unlike many mast cell tumors involving viscera. We suggest that the differences between the cells in the typical visceral and intestinal tumors confirm and extend the concept of the existence of morphologic and functionally heterogeneous populations of mast cells occurring in different anatomical locations of the body.

Animals↗
PubMedDate not supplied

Androgen receptor levels and androgen contents in the prostate lobes of intact and testosterone-treated Noble rats.

Plasma testosterone (T) levels were correlated with androgen receptors, tissue content of T, and 5 alpha-dihydrotestosterone (DHT) in the three anatomically-discrete prostate lobes of intact and castrated Noble (Nb) rats bearing T-filled silastic capsules. Differences in androgen receptor content and tissue androgen levels were observed among the three prostatic lobes of intact Nb rats. Total (cytosolic and nuclear) androgen receptor levels were highest in the ventral prostate followed by the dorsolateral and anterior prostate lobes. In the ventral and anterior prostate, androgen receptors were found to be equally distributed between cytosols and nuclear extracts, whereas in the dorsolateral prostate, androgen receptors were predominantly nuclear (cytosolic: nuclear = 1.5). The ventral prostate had the highest total androgen content and DHT was the major tissue androgen in all three lobes. The ratio of tissue DHT:T varied among the lobes; the highest value was observed in the dorsolateral prostate. The higher proportions of nuclear androgen receptor, as well as the elevated tissue DHT:T found in the dorsolateral prostate compared to other lobes, suggest that differences in the androgen activation process may exist between the dorsolateral prostate and other prostatic lobes. Despite lower plasma and tissue T levels, the DHT content, weight and cytodifferentiation in all lobes of T-treated castrated rats closely approximated the situation found in intact animals. Total androgen receptor levels were, however, elevated in all prostatic lobes of T-treated, castrated rats as compared to intact controls. These increases were primarily attributed to the augmented levels of androgen receptor in the nuclear extracts of the three prostate lobes. Exposure of the prostate to a constant level of T, produced by silastic implantation, might be responsible for the higher total androgen receptor levels and enhanced nuclear androgen receptor retention found in the prostates of T-treated, castrated rats.

Androgens↗