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Biomedical subjects

M Muto

Publications and source records attributed to M Muto.

At least 181 records · Page 10Linked to original sources
PubMed1977

Estimation of gene reiteration from hybridization kinetics in moderate deoxyribonucleic acid excess.

Theoretical calculations were carried out to clarify how the DNA/RNA or the DNA/cDNA (complementary DNA) ratio in the hybridization reaction mixture affects the kinetics of DNA-RNA or DNA-cDNA reassociation, and theoretical formulae were derived as a function of these ratios. From these formulae, it was found that the DNA/RNA of the DNA/cDNA ratio did not much affect the initial reaction rates of hybridization, but greatly affected the terminal value for the extent of hybrid formation. Therefore the results obtained when one normalizes the experimental data for hydridization and derives the reiteration frequency from a number called the 'half Cot' (Cot 1/2) are not accurate, especially in the presence of a moderate excess of DNA. A simple method for the estimation of gene reiteration was demonstrated that did not use the half Cot value in the determination. This simple method is useful even if DNA-RNA or DNA/cDNA hybridization are done with a moderate excess of DNA. With mouse myeloma cells as a model system, the gene reiteration of the 28S rRNA cristron was determined.

DNA↗
PubMed1977

Cellular transformation and differentiation. Effect of Rous sarcoma virus transformation on sulfated proteoglycan synthesis by chicken chondrocytes.

Incorporation of sulfate into sulfated proteoglycans by isolated chicken chondrocytes was inhibited up to 74% by transformation with the Rous sarcoma virus, and a similar inhibitory effect was observed on acetate incorporation into chondroitin sulfate. Slower sedimenting sulfated proteoglycans appear after the viral transformation. The ratio of chondroitin 4-sulfate to chondroitin 6-sulfate in these slower sedimenting sulfated proteoglycans was different from that of normal chondrocytes, but the chain lengths of sulfated glycosaminoglycans produced by normal chondrocytes and transformed chondrocytes were not significantly different. Chondrocytes were also infected with a temperature-sensitive mutant of RSV, ts LA24, which has a temperature-sensitive lesion in the transforming gene. Hyaluronic acid production by these cells was increased, and the slower sedimenting sulfated proteoglycan was produced only at the permissive temperature.

Acetates↗
PubMed1977

Immunochemical isolation of gamma-globulin mRNA and estimation of immunoglobulin gene reiteration.

The polyribosomes synthesizing gamma-globulin have been isolated by the achievement of specific precipitation using bentonite-treated anti-IgG antibody. The RNA extracted from the immunochemically precipitated polysomes was tested for its ability to direct the synthesis of proteins in a cell-free system. The specific gamma-globulin-synthesizing activity (cpm of gamma-globulin synthesized/microgram RNA) of this RNA was 10-fold greater than that from total polysomes. gamma-globulin mRNA (messenger RNA) isolated by immunoprecipitation was more than 89% pure with respect to contamination by other species of mRNA. The products synthesized by the cell-free system were also analyzed by sodium dodecyl sulphate(SDS)-polyacrylamide gel electrophoresis. This RNA has been hybridized with mouse myeloma DNA. The estimation of immunoglobulin gene reiteration was carried out using hybridization kinetics with consideration given to the DNA/RNA ratio since the estimation from the "half Cot value" is not accurate. The results suggest that in the mouse there are about 20 copies per subgroup of genes coding for the variable region of the H and L chains.

Alleles↗
PubMed1977

Transformation of chicken chondrocytes by Rous sarcoma virus.

Chicken chondrocytes isolated from 11-day-old chicken vertebrate cartilage were transformed by Rous sarcoma virus ts LA24 of the Prague strain as well as by the wild-type Prague strain of Rous sarcoma virus. The morphology of chondrocytes transformed by Rous sarcoma virus ts LA 24 was dependent on the temperature, and the change was reversible. A similar but irreversible change in morphology was observed with chondrocytes transformed by wild-type virus. Hyaluronic acid production and deoxyglucose transport were markedly increased in the transformed chondrocytes. A marked increase of labeled acetate incorporation was observed with the transformed chondrocytes. In contrast to the normal chondrocytes, the labeled hyaluronic acid synthesized by the transformed chondrocytes was mostly released into the culture medium.

Animals↗
PubMed1976

Transabdominal mucosal transection of the esophagus for the treatment of esophageal varices.

Transabdominal mucosal transection of the esophagus was applied to 20 patients with esophageal varices. The operative procedure involves a longitudinal incision of the muscular layers which follows transection and reanastomosis of the denuded mucosa. With the preservation the muscular structure, postoperative complications such as anastomotic leakage, stenosis or regurgitation, have been minimized. The effect of this procedure on the varices proved satisfactory.

Abdominal Muscles↗
PubMed1976

A scanning and transmission electron microscopic study on rat bone marrow sinuses and transmural migration of blood cells.

Bone marrow sinuses of young rats were examined under the scanning (SEM) and transmission electron microscopes (TEM). Marrow sinus wall was composed of three layers: an inner or luminal endothelium, an outer or adventitial cell layer, and a basal lamina in between. The luminal surface of the endothelial cells was quite smooth and showed some fenestrations, which could be divided into two types according to their size. One was represented by larger fenestrations (1-3 mum in diameter) which were presumed to be formed transiently at the site of blood cell migration, while the other by small pores (0.1 mum) grouped into a cribriform area. The adventitial cells showed a discontinuous layer in the TEM. Under the SEM, the discontinuity corresponded to the spaces formed between the cytoplasmic attenuations of the cells. Blood cell migration from the extravascular hemopoietic tissue into the sinus lumen was numerously observed. The migration occurred not through an intercellular gap, but through the larger intracellular fenestration of the endothelial lining mentioned above. A number of megakaryocytes were identified by their bulky cytoplasm in the parenchyme. Figures suggesting the sequence of platelet liberation from this cell could be demonstrated. First, the megakaryocyte extended its peripheral cytoplasmic processes into the sinus through endothelial fenestrations. The processes, being conspicuously extended, became periodically constricted. Finally, platelets were believed to be produced by separation at the constricted portions and liberated to circulation. The occurrence of a few endothelial fenestrations apparently unassociated with blood cell migration may possibly be ascribed to detachment of a blood cells due to vascular perfusion. The functional significance of the adventitial cell was discussed in association with blood cell migration.

Animals↗
PubMed1976

Production of immunoglobulins by tumor cell lines from avian lymphoid leukosis.

Two avian lymphoma cell lines, 1104-X-5 and 1104-B, were examined for ability to produce immunoglobulin. They were found to produce and release the components of immunoglobulins related to IgG and IgM. The analysis of sucrose density gradient and gel electrophoresis suggested that these components might consist of light chains and fragments of heavy chains.

Animals↗