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Biomedical subjects

N Catsimpoolas

Publications and source records attributed to N Catsimpoolas.

At least 37 records · Page 2Linked to original sources
PubMed1976

The effect of cryogenic storage on human erythrocyte membrane proteins as determined by polyacrylamide-gel electrophoresis.

A study was conducted to determine the effects of freezing on the major membrane proteins of isolated human erythrocyte membranes. Membranes in low or normal ionic strength medium were frozen at slow or fast freezing rates. The membrane protein composition and elution of proteins from the membranes were studied utilizing polyacrylamide-gel electrophoresis in a sodium dodecyl sulfate or an acetic acid-urea-phenol solvent system. Neither a change in the composition of the membrane proteins nor any elution of membrane protein during freezing and thawing was observed. The data indicate that any human erythrocyte membrane damage during freezing and thawing was not related to a change in major membrane protein composition. Human red cell membranes were stable at --80 or --196degreesC in the absence of a cryoprotective agent.

Blood Preservation↗
PubMed1976

Density gradient electrophoresis of mouse spleen lymphocytes: separation of T and B cell fractions.

Preparative electrophoresis in an isotonic Ficoll--sucrose density gradient has been employed for the separation of mouse (C57Bl/6J) spleen lymphocyte subpopulations. The separated cells were pooled into six fractions according to their relative position (Rp) within the total cell distribution. In general, the high mobility cells were identified as T lymphocytes. These cells exhibited immunofluorescence upon reaction with fluorescein isothiocyanate-conjugated mouse anti-theta globulin and responded in vitro to phytohemagglutinin stimulation. The low mobility cells were activated in vitro by E. coli lipopolysaccharide and showed immunofluorescence upon reaction with fluorescein isothiocyanate-conjugated anti-mouse Ig which is typical of mouse B lymphocytes. Both T and B cells were completely isolated from each other in certain fractions of very high and very low mobility, respectively. Overlapping of the two distributions was observed in the intermediate mobility fractions. The method which utilizes an inexpensive commercially available apparatus should be useful for the preparation of other lymphocyte subpopulations differing in surface charge.

Animals↗
PubMed1976

Electrophoretic separation of radioisotopically labeled mouse lymphocytes.

A new preparative method is described for the separation and direct electrophoretic comparison of the distribution profile of radioisotopically labeled cells. The cell populations to be compared are labeled separately with different radioisotopes (e.g., 51Cr and 99mTc) and mixed. The cell mixture is subjected to density gradient electrophoresis and the distribution of each radioisotope in the collected fractions is ascertained by differential gamma counting. In the case of uniform label uptake by the cells in each distribution, the radioactivity counts represent cell frequency. Nonuniform labeling allows useful comparisons only in terms of relative mobility distribution. Model experiments performed with 51Cr- and 99mTc-labeled mouse thymocytes and spleen cells are in general agreement with mobility distribution results obtained previously by free flow electrophoresis.

Animals↗
PubMed1975

Size and charge heterogeneity of rat tissue ferritins.

Ferritins purified from horse spleen and from rat liver, kidney, heart and hepatoma were analyzed by quantitative polyacrylamide gel electrophoresis. From the migration characteristics of these ferritins at several gel concentrations, Ferguson plots were constructed and the molecular sizes and charges (apparent valences) together with their statistical variability were obtained by applying Rodbard computer programs to the data. Finally, ellipses were drawn describing the 95% confidence limits of these data for size and charge and were used to identify those ferritins that differed in size and/or charge. By these criteria, many of the tissue ferritins were differentiated from one another in terms of their molecular size and/or charge. Among the various tissue ferritin monomers, the molecular sizes were essentially similar (420 000-490 000) except for the two heart ferritins which were larger (530 000 and 626 000, respectively). However, the estimated charges on rat liver, kidney and hepatoma monomers (30-38 net protons per molecule) differed from that of spleen monomer (51 net protons per molecule) while the larger rat heart ferritin also had a greater charge (83 net protons) than the smaller (40 net protons). Apoferritins prepared chemically by removal of iron from the holoferritins had migration properties indistinguishable from the parent holoferritins. The migration properties of minor (dimeric) ferritin bands on the gels were compared with those of the monomer bands. The molecular sizes of the minor bands were larger than those of the major bands, and were not inconsistent with a doubling in size. However, charge differences varied, being either similar for major and minor forms (spleen ferritin), approximately twice for the minor form (rat hepatoma ferritin) or five times greater for the minor form (rat liver ferritin). These differences in behavior were confirmed by using minimally sieving gels, on which the major bands of horse spleen ferritin failed to separate whereas those of rat liver ferritin were readily separable. It is concluded that dimers of ferritins from different tissues may associate in different ways.

Animals↗
PubMed1975

Scanning isoelectric focusing of cholera enterotoxin in polyacrylamide gels.

Scanning isoelectric focusing has been employed for continuous monitoring of the isoelectric spectrum of highly purified cholera enterotoxin in 4% polyacrylamide gels containing 2% ampholytes pH 3-10. The resolution obtained by this technique is of high order because at no instance during focusing interruption of current occurs and thus diffusion of the isolated protein moieties is suppressed. An added aspect of scanning isoelectric focusing was that it allowed estimation of the minimal focusing time of cholera enterotoxin. Thus under the standard assay procedure, the main basic component of cholera enterotoxin was focused in 5800 sec, while the other at least 3 minor acidic and anodic components were focused in approximately 19000 sec. Focusing of cholera enterotoxin in the presence of 6 mu urea allowed the visualization of 5 well defined and about equal components. The proteinaceous nature of the observed peaks was verified by scanning at wavelenghts other than 280 nm, staining of gels for protein, and varying the concentration of the enterotoxin. The design of scanning isoelectric focusing equipment is presented. Reproducibility, economy of sample, and ampholytes and simplicity of experimental technique were some of the features of this apparatus. The resolution of scanning isoelectric focusing was found to be superior to that of ordinary disc and SDS gel electrophoresis.

Acrylamides↗