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Biomedical subjects

D M Kirkham

Publications and source records attributed to D M Kirkham.

5 recordsLinked to original sources
PubMed1992

Demonstration of inhibitory guanine nucleotide regulatory protein (Gi) function in liver and hepatocyte membranes from streptozotocin-treated rats.

By using a defined plasma-membrane preparation, functional inhibition of adenylate cyclase activity by the inhibitory G-protein (Gi) was observed in liver and hepatocyte membranes from rats made diabetic by streptozotocin. These observations contrast with previous reports which have shown a defect in Gi in this diabetic animal model. These results suggest that Gi function is not impaired in the livers of streptozotocin-treated rats and that plasma-membrane preparation procedures should be clearly defined before ascribing Gi defects to a pathological state such as diabetes.

Adenylate Cyclase Toxin↗
PubMed1991

Evaluation of inhibitory guanine nucleotide regulatory protein Gi function in hepatocyte and liver membranes from obese Zucker (fa/fa) rats and their lean (Fa/?) littermates.

Previous studies have shown that hepatocyte and liver membranes from insulin resistant animals exhibit an impairment of inhibitory guanine nucleotide binding regulatory protein, Gi function, such that a Gi defect may contribute towards the diabetic syndrome. In the current studies, it is shown that the demonstration of Gi activity in liver and hepatocyte membranes is dependent critically on the membrane preparation technique. A technique is defined that allows functional Gi activity to be demonstrated in liver and hepatocyte membranes from both lean (Fa/?) and obese (fa/fa) Zucker rats. Consequently, previous reports on the loss of Gi function in insulin resistant states require revaluation.

Adenylyl Cyclases↗
PubMed1983

Lymphocyte enzyme activities in East African blacks: decrease in 5'nucleotidase and possible relation to immunosuppression.

Microanalysis of subcellular organelle marker enzymes was applied to cryopreserved lymphocytes (obtained and processed in the field) from East African blacks with moderate to severe malnutrition and subject to locally endemic parasitic and infectious diseases. An initial study demonstrated that activities of these enzymes, with the partial exception of catalase, were stable to cryopreservation. Cryopreserved and thawed lymphocyte specimens (1 to 3 X 10(6) viable cells) from 26 Africans and 20 Caucasian controls were studied. There was a highly significant decrease in 5'nucleotidase activity in these African subjects. Activity of another plasma membrane enzyme, gamma-glutamyl transferase, and of marker enzymes for other intracellular organelles, was not significantly different between the two groups, indicating that the nucleotidase alteration is highly specific. 5'Nucleotidase activity in a group of 17 East African blacks of high socio-economic status lay between the values obtained in the other two groups and was not significantly different from either. Further studies on 5'nucleotidase showed no evidence that the enzyme is functionally different in Africans. The differences in activity of this enzyme in Africans may reflect the known immuno-suppressive effects of infectious disease and malnutrition or may have a genetic basis which may in turn be associated with the pathogenesis of secondary immunodeficiency.

5'-Nucleotidase↗