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Biomedical subjects

Y Oka

Publications and source records attributed to Y Oka.

At least 577 records · Page 32Linked to original sources
PubMed1981

Agglutination antibody responses to Trypanosoma gambiense homogenate in mice treated with dextran sulfate 500 and carrageenan.

Dextran sulfate 500 and carrageenan, sulfated polysaccharides, have been considered as macrophage-toxic giving profound effects on the immune response. This work deals with agglutination antibody responses to T. gambiense homogenate in mice treated with dextran sulfate 500 and carrageenan. Antibody responses to the first immunization were suppressed in mice treated with the agents before the first immunization but reverse was the case with the response to the second immunization. These suppression and enhancement appeared to be dependent on the timing of treatment in regard to the time of the first immunization. The enhanced antibody response was abolished by either treating the mice with anti-thymocyte serum or transferring of spleen cells treated with anti-thymocyte serum into mice. Thus, the enhancement of antibody response is seemingly attributable for the most part to potent memory T cells induced by treatment with the agents.

Agglutination Tests↗
PubMed1980

The origins of the centrifugal fibers to the olfactory bulb in the goldfish, Carassius auratus: an experimental study using the fluorescent dye primuline as a retrograde tracer.

The origin of the centrifugal fibers to the olfactory bulb in the goldfish was examined by injecting a fluorescent dye, primuline, into the olfactory bulb by means of hydraulic pressure. Three to five days after the primuline injection, which was confined to the unilateral olfactory bulb, a large number of primuline-labeled perikarya appeared in two telencephalic areas on the ipsilateral side: the area ventralis telencephali pars dorsalis (Vd) and the ventral part of the area dorsalis telencephali pars lateralis (Dlv). No labeled cells were observed in the other olfactory bulb or in the contralateral telencephalic hemisphere or more posterior part of the brain. A combination of the primuline injection and the transection of either the medial or lateral olfactory tract showed that the main course of the centrifugal fibers was through the medial olfactory tract. These results may support Sheldon's opinion that the so-called tractus olfactorius ascendens, which corresponds to the medial part of the medial olfactory tract, is a centrifugal bundle originating from the cells in the nucleus medianus. The areas of the telencephalic hemisphere into which the olfactory bulbar fibers projected were also examined and compared with the originating areas of the centrifugal fibers. There was a considerable overlap between these two areas. This suggests a reciprocal connection between the olfactory bulb and the telencephalon.

Animals↗
PubMed1980

Effect of a high glucose diet on insulin binding and insulin action in rat adipocytes. A longitudinal study.

To elucidate the mechanisms whereby changes in dietary composition affect the action of insulin on glucose metabolism, insulin binding and glucose uptake and oxidation have been studied in epididymal fat pad adipocytes from rats fed high glucose diets for 5 and 10 days. After 5 days, insulin binding was increased, the mainly to an increased number of receptors (3.4 X 10(5) vs. 2.4 X 10(5) sites per cell) in spite of increased plasma insulin levels (3.0 +/- 0.2 vs. 2.1 +/- 0.1 microgram/l; P < 0.05). The maximal response of glucose oxidation to insulin was increased (925 +/- 55 vs. 510 +/- 58 n moles/2 X 10(5) cells/2h; P < 0.01) and the dose-response curve of glucose uptake was shifted to the left. After 10 days, receptor number decreased to the control level and the effect of insulin on glucose uptake and oxidation (% basal) were similar to controls. Thus, in the early stage of high glucose feeding, insulin receptor number, and insulin sensitivity of glucose uptake, and insulin responsiveness of glucose oxidation were increased.

Adipose Tissue↗
PubMed1980

Application of transesophageal echocardiography to continuous intraoperative monitoring of left ventricular performance.

Transesophageal M mode echocardiography was used for continuous monitoring of left ventricular dimensions in 21 patients (11 with valvular and 10 with coronary heart disease) undergoing open heart surgery. Echocardiograms were recorded in six stages of the procedure and simultaneous measurements of cardiac output (with dye dilution) and atrial pressures were made. Measurements of left ventricular diameters with the transesophageal technique correlated excellently with the corresponding measurements obtained with the standard parasternal method. In patients with volume overload, surgical correction was accompanied by a decrease in diastolic dimension, velocity of circumferential fiber shortening, mid wall stress and end-diastolic stiffness, and an increase in cardiac output. Pericardial and chest wall closures generally caused a significant decrease in cardiac output, and correlated with a decrease in diastolic diameter and an increase in the stiffness constant of the left ventricle. Thus, the decrease in cardiac output may have been due to decreased distensibility of the ventricular cavity secondary to mechanical restriction by the pericardium and chest wall. Pericardial opening caused a significant delay in septal motion that was reversed by closing the pericardium. This study confirms the validity of transesophageal echocardiography and its usefulness in monitoring changes in ventricular function during cardiac surgery.

Adult↗
PubMed1980

Inverted terminal repeat sequence in the macronuclear DNA of Stylonychia pustulata.

The structure of macronuclear DNA of a hypotrichous ciliate, Stylonychia pustulata, was examined by both electron microscopy and nucleotide sequence analysis. The DNA in the macronucleus consists of small linear molecules with average length of about 3400 base pairs (bp). Most, if not all, of these DNA molecules have identical inverted terminal repeat sequence of 20 nucleotide residues. This sequence is 5'-CCCCAAAACCCC-AAAACCCC.

Animals↗
PubMed1980

Effects of dextran sulfate 500 on protective responses to sublethal Trichomonas foetus infection in mice.

In order to analyze the host-parasite interactions in experimental trichomoniasis, the growth of Trichomonas foetus in the peritoneal cavity and changes in the peritoneal exudate cells were followed in mice treated with dextran sulfate 500 (DS 500), a known macrophage-toxic agent. Light microscopic observation showed that DS 500 treatment induced degeneration of peritoneal macrophages within about 48 hr after the treatment and the damaged macrophages did not phagocytize the parasites, whereas peritoneal neutrophils and lymphocytes were not affected by the drug. In the DS 500-treated mice, growth of parasites in the peritoneal cavity was accelerated and a high susceptibility of the mice to T. foetus infection was observed. These results indicate that macrophages play the most important role among the peritoneal exudate cells in resistance to T. foetus infection, especially during the early stage of infection.

Animals↗