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Biomedical subjects

R J Davidson

Publications and source records attributed to R J Davidson.

At least 163 records · Page 9Linked to original sources
PubMed1982

The toxic effects of combined administration of cyclosporin A and gentamicin.

The toxic properties of cyclosporin A and gentamicin give alone and in combination were investigated in groups of Sprague-Dawley rats over a 7-day period. Administration of each drug on its own caused minor impairment of renal and hepatic function: cyclosporin A had additional structural effects on renal tubules and lymphoid tissue. Combined therapy resulted in acute renal failure with two distinct zones of damage in the renal proximal tubules--gentamicin-induced necrosis of the convoluted segment and cyclosporin A-related vacuolation of the straight segment--and the effects on hepatic and haematological parameters were more pronounced. The results indicate the need for caution before cyclosporin A and another potentially nephrotoxic drug and administered together and for specific monitoring or renal function where such combined therapy is considered essential.

Acetylglucosaminidase↗
PubMed1981

The mean red cell volume in diabetes mellitus.

The Coulter mean red cell volume was found to be significantly elevated in a sample of 100 diabetic patients compared with 200 normal subjects (p less than 0.01). There was no correlation between the mean red cell volume level and the type of diabetes, its method of treatment or degree of control as measured by random blood glucose and glycosylated haemoglobin levels.

Adult↗
PubMed1981

Pathological changes developing in the rat during a 3-week course of high dosage cyclosporin A and their reversal following drug withdrawal.

Adult Sprague-Dawley rats given cyclosporin A (Cy A orally in a dose of 100 mg/kg/48 hr for 21 days displayed pronounced suppression of humoral immunity to sheep red blood cells. They showed hair loss and failure to gain weight and exhibited a progressive increase in serum urea, serum creatinine, and urinary N-acetyl-beta-D-glucosaminidase (NAG) activity, with a fall in urea clearance rate. Hypoalbuminemia and hyperbilirubinemia were observed in combination with a significant decrease in serum aspartate aminotransferase (AAT) and alkaline phosphatase levels. At 2 weeks, there was significant lymphopenia with the appearance of atypical lymphocytes in the peripheral blood. Autopsies performed on animals killed at 3 weeks revealed no light microscopic or ultrastructural differences between test and control animals, apart from some reduction in overall bone marrow cellularity in the former. During the 3-week period following withdrawal of Cy A, renal and hepatic function reverted to normal and a rebound lymphocytosis occurred. Only one of six rats autopsied 3 weeks after cessation of CY A administration showed reduced bone marrow cellularity. This study indicates that the rat may prove to be a useful experimental model for further investigation of te functional and structural changes which may be encountered in the clinical use of Cy A.

Alkaline Phosphatase↗
PubMed1981

Haematological changes following systemic injection of purified carrageenans (kappa, lambda and iota).

Kappa, lambda and iota carrageenans were administered i.p. (125 mg/kg) to groups of Sprague-Dawley rats. Each carrageenan (but especially kappa and lambda) caused thrombocytopenia and red-cell damage, particularly burring, within 2 days. This was followed by rebound thrombocytosis and persistent anaemia, accompanied by a reticulocytosis. A 2-fold increase in fibrinogen was observed at 24 or 48 h. All groups showed a leucopenia at 1 h, then a progressive leucocytosis, maximal at 48 h (kappa and lambda) or Day 7 (iota). Between 1 and 24 h there was a significant lymphopenia, followed by lymphocytosis (kappa and lambda) including Turk cells and pronounced neutrophilia in all groups. Monocytosis occurred in response to each carrageenan on Days 2-4 (kappa) or Day 7 (lambda and iota). Injection of kappa carrageenan was characterized by the presence (up to Day 7) of carrageenan-positive material, in the form of floccules, within the peripheral blood, and by Day 7 the appearance of histiocyte-type macrophages which exhibited haemo-phagocytosis. In the lambda group, carrageenan-positive granules were observed in the cytoplasm of mononuclear cells throughout the experimental period. No intracellular carrageenan was demonstrable in peripheral blood in the iota group or within neutrophils of any of the injected animals. Overall marrow cellularity was not altered by carrageenan, but small numbers of kappa- and lambda-containing macrophages were identified. Splenomegaly was consistently observed and in histological section carrageenan-positive macrophages were detected in the red pulp, particularly in the lambda group.

Animals↗
PubMed1980

Stressed power motivation, sympathetic activation, immune function, and illness.

Previous research has reported that individuals high in the need for Power, high in inhibition, and high in power stress (the HHH group) are more likely than other individuals to report more severe illnesses. The present study investigates the possibility that the mechanism underlying this relationship is greater sympathetic activation in the HHH group which has an immunosuppressive effect. College males with the HHH syndrome reported more frequent and more severe illnesses than other individuals, as in previous studies. More of the HHH than other subjects also showed above average epinephrine excretion rates in urine and below average concentrations of immunoglobulin A in saliva (S-IgA). Furthermore, higher rates of epinephrine excretion were significantly associated with lower S-IgA concentrations, and lower S-IgA concentrations were significantly associated with reports of more frequent illnesses. The findings are interpreted as consistent with the hypothesis that a strong need for Power, if it is inhibited and stressed, leads to chronic sympathetic overactivity which has an immunosuppressive effect making individuals characterized by this syndrome more susceptible to illness.

Adult↗
PubMed1980

Cytoplasmic vacuolation of peripheral blood cells in acute alcoholism.

Cytoplasmic vacuolation of peripheral blood leucocytes is reported in three patients with acute alcoholism. Apparently this is the first report of vacuolation of peripheral blood leucocytes associated with acute alcoholism. Apart from any direct cytotoxic effect of alcohol the metabolic acidosis and hypoglycaemia associated with acute alcoholic poisoning may be important factors in the pathogenesis of the morphological changes.

Adult↗
PubMed1979

Anaemia in twin pregnancy.

A total of 123 twin pregnancies were studied, 68 by records analysis only, and 55 by serial haematological assessment in detail. The incidence of low haemoglobin levels is found to be greater than in singleton pregnancy; evidence of iron and folic acid deficiency is common in sternal marrow aspirates but not in peripheral blood films. Routine haematinic prophylaxis in twin pregnancy is not advocated.

Anemia↗