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Biomedical subjects

J O'Brien

Publications and source records attributed to J O'Brien.

At least 235 records · Page 13Linked to original sources
PubMed1984

The effect of glucagon on urine amylase in various animal species.

Glucagon effects on the kidney include increased water, creatinine, and amylase clearance. We have compared these effects in several laboratory animal species. Although every species responded to glucagon, 1 mg iv, by some alteration in renal function there were differences in the degree and direction of the changes. Glucagon caused an increase in amylase clearance in four of the six species studied and an increase in creatinine clearance in four. An increase in urine flow tended to occur in all species. An increased amylase clearance is a feature of acute pancreatitis, and raised glucagon levels have been found during attacks. It is possible that the two are causally related. In the experimental situation, timing of urine collections and species differences were found to be of critical importance in exploring this possibility.

Amylases↗
PubMed1984

Amylase excretion after exercise.

Increase in amylase excretion in the urine in response to 8 days of aerobic running is delayed until after the athletes have rested for 24-48 h. In contrast, the amylase creatinine ratio is increased immediately after intense short-term exercise. The mechanism for these differences is unknown, but the timing of the amylase excretion pattern after long- and short-term exercise is similar to the urinary amylase after continuous and single bolus intravenous glucagon.

Amylases↗
PubMed1982

Role of veiled cells in lymphocyte activation.

Peripheral blood lymphocytes from normal rabbits or from rabbits hyperimmunized with human immunoglobulin were cultured in 20-microliters hanging droplets. The cultures were stimulated with concanavalin A or, in the case of cells from sensitized animals, with human immunoglobulin. The addition to the cultures of small numbers of autologous or allogeneic veiled cells separated from afferent lymph increased the responses to low doses of the stimulants, particularly when the cells were cultured at low cell densities or for short periods of time. At high cell densities or at longer periods of culture, stimulation occurred in the absence of added veiled cells and was associated with clumping of the lymphoid cells and development of cells which morphologically resembled veiled cells found in afferent lymph. The enhanced responses upon addition of small numbers of veiled cells were also correlated with the formation of lymphoid aggregates which were frequently held together by the elongated processes of a single veiled cell. The observations support the view that the veiled cells are lymph-borne precursors of dendritic cells in the lymph nodes. This may provide an in vitro model for the cellular relationships which occur in paracortical cords of lymph nodes following antigenic stimulation.

Animals↗
PubMed1982

Assessing methods for measuring compliance with a fat-controlled diet.

This study assessed the relative validity of the following non-laboratory measures of compliance with a fat-controlled diet by hypercholesterolemic males: quantitative and qualitative measures of compliance derived from three-day food records and structured interviews, and summary ratings by nutritionists and interviewers. The quantitative measures of consumption referred to: saturated fat, linoleic acid, polyunsaturated fat, P/S ratio and cholesterol. The non-laboratory measures were assessed using the following two laboratory measures as criteria of validity: serum cholesterol concentration and the proportion of linoleic acid among the fatty acids of the serum cholesteryl esters. The results showed that, with respect to quantitative measures, the food record and interview manifested approximately equal validity, with the former marginally more valid. However, under certain conditions qualitative measures, such as patients' self-ratings, were about as valid as the more rigorous and expensive quantitative measures. Characteristics of the patient influenced the validity of the various measures. Validity was enhanced by the simultaneous use of certain combinations of measures.

Adult↗
PubMed1980

Conditions for measuring DNA synthesis in PHA stimulated human lymphocytes in 20 microliters hanging drops with various cell concentrations and periods of culture.

We have studied conditions for measuring the uptake of [3H]thymidine ([3H]Tdr) by human lymphocytes in inverted microcultures, varying cell concentrations and periods in culture. Analysis of variance of the log values for [3H]Tdr uptake may be used to separate effects of variables and their interactions. A pulse time of 2 h, a total thymidine concentration of about 1 microgram/ml and a specific activity of [3H]Tdr of 2 Ci/mmole were optimal. Variables such as cell concentration, period of culture, type of serum and dose of PHA were shown to interact, suggesting that these variables should be examined together especially when comparing different samples of lymphocytes. Conditions for doing this simply in small volumes are now available for culturing, thymidine pulsing, harvesting and analysis of data.

Cell Division↗
PubMed1980

Metastable creatine kinase MM and complexes of creatine kinase BB and immunoglobulin G, "atypical" isoenzymes with similar electrophoretic mobility.

Metastable creatine kinase MM isoenzyme was isolated and partially purified from homogenates of myocardium and skeletal muscle by gradient elution on carboxymethyl cellulose. This variant isoenzyme migrated between the MM and MB isoenzymes on agarose electrophoresis, accounted for 3.5% of the total creatine kinase activity in each tissue, was not a macromolecule, and had stable electrophoretic mobility only in borate buffer (0.02 mol/L). By comparison, the creatine kinase isoenzymes with similar "atypical" electrophoretic mobility in serum specimens were complexes of the BB isoenzyme and immunoglobulin G. These complexes were measured by a radioimmunoassay specific for the creatine kinase B-subunit and eluted predominantly with the MB isoenzyme in a commercial anion-exchange reagent system.

Creatine Kinase↗
PubMed1979

A simple technique for harvesting lymphocytes cultured in Terasaki plates.

A simple method has been developed for harvesting lymphocytes from Terasaki microplates based on a culture technique where the plates are inverted and the cells grown on the hanging meniscus of the medium in each well. Sixty individual filter discs were prepared in wells in a polycarbonate harvesting plate. A dry Terasaki plate was used to cut these filters with the harvester acting as a die. The inverted culture plate was then lowered onto the harvester to allow the cells on the meniscus from each well to be absorbed on the appropriate filter disc. The culture plate was then discarded and the cells on the filters washed in the harvester. The wash solutions were removed by suction through holes below each filter. The time taken to harvest the cultures from 60 wells of a plate was 3--5 min.

Cell Separation↗
PubMed1978

Effect of levamisole on metabolism of phagocytic cells.

The effect of levamisole (LMS) on glucose metabolism was studied using a protozoan phagocytic model and human leukocytes. At concentrations of greater than 10 microgram/ml, LMS inhibited glucose metabolism in the protozoan phagocytic model. Glucose metabolism in both the phagocytic model and normal peripheral blood leukocytes was, however, minimally altered when exposed to levels of LMS of less than 10 microgram/ml. In contrast, myeloblasts from a child with leukemia seemed to have increased metabolic activity and 5 microgram/ml of LMS markedly reduced the glucose metabolism. These preliminary studies suggest that LMS can alter glucose metabolism of certain cells and that some malignant cells may be directly inhibited metabolically by LMS.

Child↗