Biomedical subjects

J Ross

Publications and source records attributed to J Ross.

At least 757 records · Page 42Linked to original sources

PubMed1975

Two techniques to make the lymphocytotoxic crossmatch more sensitive: prolonged incubation and the antiglobulin test.

Two techniques capable of increasing the sensitivity of the lymphocytotoxic crossmatch test were compared for sensitivity and practically using the fluorochromasia modification of the cytotoxicity test. Prolonging the incubation period after addition of complement in the standard test resulted in further positive reactions. Modification of the test by addition of antiglobulin reagent increased the reactivity more than prolonged incubation of the standard test. The fluorochromasia adaptation of the antiglobulin test had sensitivity equivalent to the original antiglobulin method. The antiglobulin technique had a number of disadvantages, and neither the prolonged incubation nor the antiglobulin procedure meet the requirements of a busy histocompatibility testing service in view of the time consumed for the first and the complexity of the second.

Coombs Test↗

PubMed1975

Induction of globin mRNA in Friend leukemia virus-infected cells and its presence in viral 60S RNA.

The Friend leukemia virus (FLV)-infected cell line, T-3-Cl-2, undergoes a form of erythroid differentiation in culture when treated with an appropriate inducer, such as dimethylsulfoxide ((CH3)2SO). Thus, whereas untreated cells contain no detectable hemoglobin, treated cells accumulate hemoglobin in quantities comparable to those in the mature mouse red blood cell. We have investigated the mechanism of hemoglobin induction by quantitating the number of globin genes and the amount of globin mRNA in cells before and during the period of hemoglobin accumulation. The results indicate the number of globin genes does not change as the cells accumulate hemogtobin: There are less than 5 globin genes per haploid genome. On the other hand, whereas cells lacking hemoglobin contain little, if any, globin mRNA, hemoglobin-containing cells accumulate, on the average, 8,000 molecules of globin mRNA per cell. The most direct, although, by no means, the only interpretation of these results is that the induction of hemoglobin synthesis involves transcriptional activation of the globin genes. Using this same cell line, we show that mouse globin mRNA sequences are also present in viral particles purified from the culture medium of globin-producing cells. These globin mRNA sequences are absent from viral particles derived from T-3-Cl-2 cells which are not producing globin mRNA. Virus-associated globin mRNA sequences sediment in association with 60S viral RNA complex as well as in free, 9S form. However, under mild denaturing conditions which result in the conversion of viral 60 S RNA to 30S and smaller forms, all the globin sequences sediment as 9S RNA. Appropriate control experiments indicate that the virus-associated globin mRNA is resistant to degradation by exogenous ribonuclease; that exogenously added globin mRNA does not become associated with the 60S viral RNA complex; and that globin mRNA can be detected in virions derived from cells both induced for and constitutively synthesizing globin mRNA. The presence of globin mRNA sequences in FLV particles has important implications in terms of our ability to distinguish between host and viral RNAs in viral particles and in terms of the possible role RNA tumor viruses might play in transduction of genetic information.

Animals↗

PubMed1975

Relationship of arterial-alveolar nitrogen tension to alveolar-arterial oxygen tension, lung volume, flow measurements, and diffusing capacity in cystic fibrosis.

Pulmonary function in children with cystic fibrosis was assessed by the arterial-alveolar PN2 difference adjusted to sublingual temperature. The resulting values were compared with the alveolar-arterial PO2 difference, arterial PCO2, and standard measurements of lung volume, flow, and diffusing capacity. The arterial-alveolar PN2 difference was nearly one half of the PO2 difference, both early in the disease and at a more advanced stage. Analysis taking into account the O2 dissociation curve and the possibility that alveolar temperature is higher than sublingual temperature suggested that all of the PO2 difference could be explained in terms of ventilation-perfusion imbalance in gas-filled units of the lung. Reduction of fractional CO uptake with increasing PN2 difference suggested that the decrease in diffusing capacity in cystic fibrosis may be explained by ventilation-perfusion inequality. A significant relationship between arterial PCO2 and the PN2 difference supported the view that ventilation-perfusion inequality is the cause of CO2 retention when present. The PN2 and PO2 differences were abnormal before the standard tests of lung volume and flow, but in general, the correlation was excellent. Because the PN2 difference was not superior to the PO2 difference in detecting early disease, and because the technical problems in its measurement are considerable, it is not recommended as a routine measurement.

Adolescent↗

PubMed1975

Increase in numbers of gonadotropin receptors on granulosa cells during follicle maturation.

The binding of both human chorionic gonadotropin (hCG) and human luteinizing hormone (hLH) to a homogeneous population of isolated intact granulosa cells from increasingly mature porcine ovaan follicles has been studied. The number of receptor sites per granulosa cell increases 35-fold as the follicle enlarges, although cell size remains constant. This may explain the increased biologic responsiveness to gonadotropin of mature cells from large follicles. The affinity for both hormones, as determined by equilibrium dissociation constants, is high, and does not appear to change significantly as the cells mature. Comparison of dissociation constants, numbers of binding sites, and competitive inhibition between hCH and hLH, indicates that these two hormones probably interact with the same receptor on the granulosa cells.

Animals↗

PubMed1975

Combined propranolol and digoxin therapy in angina pectoris.

The effects of oral propranolol and digoxin and digoxin alone and in combination on angina frequency, heart size, systolic time intervals and treadmill exercise tolerance, were assessed in 20 patients with coronary heart disease. Oral propranolol alone reduced the average frequency of angina pectoris from 16 to 7 attacks per week (P less than 0.02). However, the mean duration of exercise was not significantly improved because 8 patients with abnormal left ventricular function exhibited a decrease in exercise tolerance. Combined propranolol and digoxin improved exercise tolerance in these patients, and, consequently, mean exercise duration in all patients increased significantly from the control value of 390 +/- 42 to 458 +/- 46 s (P less than 0.01). Propranolol alone also resulted in a significant increase in left heart size from 46.5 +/- 1.3 to 47.7 +/- 1.5 mm/m2 (P less than 0.001), which was reversed by the addition of digoxin. Therefore, oral propranolol combined with digoxin is advantageous in patients with angina pectoris who have abnormal ventricular function or large hearts.

Administration, Oral↗

PubMed1975