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Biomedical subjects

M C Perry

Publications and source records attributed to M C Perry.

At least 145 records · Page 8Linked to original sources
PubMed1976

Lead and PCB's in canvasback ducks: relationship between enzyme levels and residues in blood.

Blood samples were taken for two successive years from canvasback ducks trapped in the Chesapeake Bay. The first winter (1972-1973) five plasma enzymes known to respond to organochlorine poisoning were examined. Abnormal enzyme elevations suggested that 20% of the population sampled (23/115 ducks) might contain organochlorine contaminants, but no residue analyses were performed. The second winter (1974) two of the same enzymes, aspartate aminotransferase and lactate dehydrogenase, and a third enzyme known to be specifically inhibited by lead, delta-aminolevulinic acid dehydratase, were assayed in 95 blood samples. Blood residues of organochlorine compounds and of lead were determined in representative samples, and the correlations between residue levels and enzyme changes were examined. The enzyme bioassays in 1974 indicated that lead was a more prevalent environmental contaminant than organochlorine compounds in canvasback ducks; 17% of the blood samples had less than one-half of the normal delta-aminole vulinic acid dehydratase activity, but only 11% exhibited abnormal aspartate aminotransferase or lactate dehydrogenase activities. These findings were confirmed by residue analyses that demonstrated lead concentrations four times higher than background levels, but only relatively low organochlorine concentrations. There was a highly significant inverse correlation between delta-aminolevulinic acid dehydratase activity and blood lead concentrations (P less than 0.01), and a weaker but significant correlation between plasma aspartate aminotransferase activity and blood PCB concentrations (P less than 0.05). It was apparent that delta-aminolevulinic acid dehydratase activity in the blood provided a sensitive and precise estimate of lead contamination in waterfowl. In canvasback ducks 200 ppb of lead in the blood caused a 75% decrease in delta aminolevulinic acid dehydratase activity, a magnitude of enzyme inhibition that disturbs heme synthesis and is regarded as detrimental in humans.

Alanine Transaminase↗
PubMed1976

Infection and mortality in captive wild-trapped canvasback ducks.

Fungal, bacterial and malarial infections, as well as malnutrition caused heavy mortality in a group of wild-trapped canvasbacks (Aythya valisineria) held in 10 X 3 X 2 m open-water pens. Deaths occurred between 21 and 158 days after confinement and were associated with infections of Aspergillus fumigatus, Escherichia coli, Staphylococcus sp., Streptococcus sp., Klebsiella sp., Enterobacter sp., and Plasmodium sp. Infection and mortality was believed to result from reduced resistance associated with confinement. Fourteen canvasbacks released onto large ponds survived throughout the period during which the penned birds died.

Animals↗
PubMed1976

Phase II studies of dianhydrogalactitol and VP-16-213 in colorectal cancer.

Phase II chemotherapy trials of dianhydrogalactitol and VP-16-213 were conducted in patients with metastatic colorectal cancer who had measurable malignant disease which served as indicators of response to therapy. Dianhydrogalactitol was given in a 5-day course at a dosage of 30 mg/m2/day. Toxic reactions included nausea, vomiting, leukopenia, thrombocytopenia, and anemia. There was a definite tendency to a compounding of hematologic toxicity with repeated courses. No evidence of objective therapeutic response was observed among 30 patients treated. VP-16-213 was given at a dosage of 130 mg/m2 on Days 1, 3, and 5. Toxic reactions included nausea, vomiting, alopecia, leukopenia, thrombocytopenia, and anemia. Hematologic toxicity was more severe in patients with elevated serum bilirubin levels. No evidence of objective therapeutic response was observed among 28 patients treated.

Adenocarcinoma↗
PubMed1975

The effect of digitonin of the stimulation by insulin of glucose uptake by isolated fat cells.

The effect of digitonin on glucose uptake by isolated fat cells in the presence and absence of insulin has been studied. At low concentrations of digitonin, the stimulation of glucose uptake by insulin was inhibited without severe cell damage as estimated by the leakage of lactate dehydrogenase from the cells. The inhibition of the insulin effect was not reversed by washing the cells or by the addition of cholesterol or lecithin-cholesterol liposomes to the incubation medium of the cells after treatment with digitonin. Cholesterol was shown to be present in the fat cells and it is suggested that the inhibition of the insulin effect is a consequence of the formation of digitonin-cholesterol complexes in the fat cell plasma membrane. Possible ways in which this may results in inhibition of the effect of insulin are discussed.

Adipose Tissue↗
PubMed1975

The clinical significance of Bence Jones proteinuria.

The detection of monoclonal light chains in the urine by the Bence Jones heat test is a useful adjuvant to the diagnosis of myeloma and other related diseases. The test is particularly helpful when no serum spike is noted. Overall, it is positive in approximately half of all patients with myeloma. In order to assess the accuracy of the test, we reviewed the records of all patients with a positive heat test for Bence Jones proteinuria during a single calendar year. Myeloma accounted for 68%, but patients with amyloidosis, the adult Fanconi syndrome, and others also had positive results. One-fifth of the results were false positive in that urine protein electrophoresis showed no spike and immunoelectrophoresis, no monoclonal protein. This group consisted largely of patients with connective tissue diseases, chronic renal failure, or nonplasmacytic malignancies. We also have seen patients who had monoclonal light chains in their urine but failed to show positive results to the heat test and were thus considered false negative. Although the heat test for Bence Jones proteins is a useful clinical test, one must be aware of both false-positive and false-negative results. Electrophoresis and immunoelectrophoresis of concentrated urine are the methods of choice for detection of a monoclonal light chain in the urine.

Amyloidosis↗
PubMed1971

The interaction of insulin with phospholipids.

1. A simple two-phase chloroform-aqueous buffer system was used to investigate the interaction of insulin with phospholipids and other amphipathic substances. 2. The distribution of (125)I-labelled insulin in this system was determined after incubation at 37 degrees C. Phosphatidic acid, dicetylphosphoric acid and, to a lesser extent, phosphatidylcholine and cetyltrimethylammonium bromide solubilized (125)I-labelled insulin in the chloroform phase, indicating the formation of chloroform-soluble insulin-phospholipid or insulin-amphipath complexes. Phosphatidylethanolamine, sphingomyelin, cholesterol, stearylamine and Triton X-100 were without effect. 3. Formation of insulin-phospholipid complex was confirmed by paper chromatography. 4. The two-phase system was adapted to act as a simple functional system with which to investigate possible effects of insulin on the structural and functional properties of phospholipid micelles in chloroform, by using the distribution of [(14)C]glucose between the two phases as a monitor of phospholipid-insulin interactions. The ability of phospholipids to solubilize [(14)C]glucose in chloroform increased in the order phosphatidylcholine<sphingomyelin<phosphatidylethanolamine<phosphatidic acid. Insulin decreased the [(14)C]glucose solubilized by phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid, but not by sphingomyelin. 5. The significance of these results and the molecular requirements for the formation of insulin-phospholipid complexes in chloroform are discussed.

Anti-Infective Agents, Local↗
PubMed1970

Factors affecting the permeability of isolated fat-cells from the rat to [42K] potassium and [36Cl] chloride ions.

1. The effluxes of (42)K(+) and (36)Cl(-) from isolated fat-cells from the rat were studied under a variety of conditions known to affect the metabolism of the cells. 2. (42)K(+) efflux from isolated fat cells was increased in a Na(+)-free-high-K(+) medium and decreased in a K(+)-free medium. The existence of K(+) exchange diffusion across the fat-cell membrane is suggested. 3. (36)Cl(-) efflux from isolated fat-cells was decreased when the Cl(-) component of the wash medium was replaced by acetate. The basal (36)Cl(-) efflux is suggested to be partly by Cl(-) exchange diffusion and partly in company with a univalent cation. 4. A variety of lipolytic stimuli, adrenaline, adrenocorticotrophic hormone, N-6,O-2'-dibutyryladenosine cyclic 3':5'-monophosphate and theophylline, increased (42)K(+) efflux from isolated fat-cells. The adrenaline stimulation was biphasic; an initial, rapid and transient increase in (42)K(+) loss from the fat-cells was followed by a slower, more prolonged, increase in (42)K(+) efflux. The initial phase was inhibited by phentolamine but not by propranolol. 5. Insulin increased (42)K(+) efflux only after preincubation with the cells.

Adipose Tissue↗
PubMed1969

Rates of effux and intracellular concentrations of potassium, sodium and chloride ions in isolated fat-cells from the rat.

1. The metabolism of K(+), Na(+) and Cl(-) has been investigated in isolated fat-cells prepared from the epididymal adipose tissue of rats. 2. Methods are described for measuring the intracellular water space, the rates of loss of intracellular (42)K(+), (22)Na(+) and (36)Cl(-) and the intracellular concentrations of K(+), Na(+) and Cl(-) in isolated fat-cells. 3. The intracellular water space, measured as the [(3)H]water space minus the [carboxylic acid-(14)C]inulin space, was 3.93+/-0.38mul./100mg. cell dry wt. 4. The first-order rate constants for radioisotope effluxes from isolated fat-cells were 0.029min.(-1) for (42)K(+), 0.245min.(-1) for (22)Na(+) and 0.158min.(-1) for (36)Cl(-). 5. The intracellular concentrations of K(+), Na(+) and Cl(-) were 146m-equiv./l., 18.6+/-2.9m-equiv./l. and 43+/-2.4m-equiv./l. respectively. 6. The total intracellular K(+) content of isolated fat-cells was determined by atomic-absorption spectrophotometry to confirm the value obtained from the radioisotope-efflux data. 7. The ion effluxes from isolated fat-cells were: K(+), 1.5pmoles/cm.(2)/sec., Na(+), 1.6pmoles/cm.(2)/sec., and Cl(-), 2.4pmoles/cm.(2)/sec. 8. The membrane potential of isolated fat-cells calculated from the Cl(-) distribution ratio was -28.7mv.

Adipose Tissue↗