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Biomedical subjects

C Miranda

Publications and source records attributed to C Miranda.

At least 109 records · Page 6Linked to original sources
PubMed1985

A bioassay method for studying factors stimulating erythropoiesis using as recipient the mouse with a functionally active erythron.

This novel bioassay method basically differs from the conventional plethoric mouse assay in the timing of the onset of induced polycythemia relative to the administration of the substances that are being tested. While the latter measures the regenerating action of erythropoietin at a time when erythropoiesis is virtually absent, the method here described evaluates the stimulatory action(s) required to maintain the normality of the process. This fact opens new approaches for studying factors involved in the quantitative govern of erythropoiesis in the steady state.

Animals↗
PubMed1984

Systemic oxygen transport and erythropoiesis in the mouse.

Removal of 15% of blood volume in the mouse increases erythropoiesis by a factor of 2.2 when measured 12 h after bleeding. Exposure of normal mice to 40% reduced barometric pressure for the same period of time increases erythropoiesis only by a factor of 1.6. The response to hypoxia takes place in the presence of a 40% reduction of oxygen consumption and tissue-venous PO2, changes which are concomitant with a 5-fold increase in plasma erythropoietin activity. The larger response in anemic animals on the other hand occurs without any detectable change in these parameters. These results cast serious doubts about the interpretation of the quantitative homeostatic control of erythropoiesis based solely on the action of erythropoietin.

Anemia↗
PubMed1983

Granada medium for detection and identification of group B streptococci.

A new starch serum medium, Granada medium, for isolation and identification of group B streptococci (GBS) anaerobically as red colonies is described. The medium contains 3.8% Proteose Peptone no. 3 (Difco), 15% soluble starch 1252 (Merck), 10% coagulated horse serum, 15 micrograms of trimethoprim per ml, and 0.06 M phosphate buffer (pH 7.8; medium pH 7.4). This medium inhibited fecal flora and at the same time supported growth of GBS. A new pigment-enhancing effect of folate inhibitors on GBS is reported and used in the formulation of the medium. The good selective and differential properties of the Granada medium favor quicker and easier detection of GBS in heavily contaminated specimens. Since the medium is convenient to use and requires only 18 h of incubation to detect and identify GBS, it should be useful in any clinical microbiology laboratory and would assist in the early detection of GBS in clinical specimens.

Bacteriological Techniques↗
PubMed1982

Effects of sphingolipids on erythroblastic maturation in the mouse.

The changes effected by injection of an extract of phospholipids obtained from the plasma of normal human donors (PLE) or an emulsion of commercially available sphingolipids on erythropoiesis in the mouse were studied. The parameters followed were 59Fe uptake by the erythroid tissue and the number of circulating reticulocytes. It was found that in the 12--24-h period following administration of PLE or purified sphingomyelin a significant increase in 59Fe uptake by circulating RBC an by their hemic fraction takes place. This change was associated with a higher 59Fe utilization by the bone marrow and with an increase in the number of circulating reticulocytes.

Animals↗
PubMed1980

Erythropoietic changes effected by foreign serum in the mouse.

Injection of foreign serum into mice increases erythrocyte formation as evaluated by ferrokinetics studies. When erythropoiesis is depressed either by fasting or plethora, the wave of erythropoiesis that follows a transient increase of endogenous erythropoietin is clearly enhanced by pretreatment of the recipients with foreign serum. The response includes a restoration of the responsiveness of the spleen of fasted mice to endogenous erythropoietin stimulation. These changes seem related to an effect of foreign serum on the transition of primitive hematopoietic progenitors into erythroid-committed progenitors.

Animals↗
PubMed1980

Acute hypocalcemia and erythropoiesis in the mouse.

Mice were made acutely hypocalcemic by injection of sodium oxalate. After the transient drop of plasma calcium marked changes in erythroblastic proliferation, number of erythroblasts and 59Fe kinetics were observed. The probable mechanism of this response that may reflect increased erythropoiesis is discussed.

Acute Disease↗
PubMed1980

Residual mannosidase activity in human mannosidosis: characterization of the mutant enzyme.

The prenatal diagnosis of affected fetuses in two families at risk for mannosidosis gave us the opportunity to study the residual alpha-mannosidase activity. We found an altered acidic alpha-mannosidase characterized by lowered affinity toward the substrate, displacement of maximal activity toward pH 4-5, thermal lability, different migration in electrophoresis, and apparent change in molecular weight at alkaline pHs. The immunological properties seem unchanged since the enzyme was precipitated by an antiacidic alpha-mannosidase antiserum. The mutant enzyme instability, provoked by dialysis, and its reactivation after addition of dialysis fluid, suggests an association-dissociation phenomenon. We propose a possible hypothesis that a low molecular weight ligand is necessary to maintain the activity of the mutant enzyme.

Centrifugation, Density Gradient↗