Search PubMed⌕ Search

Biomedical subjects

T Tsuda

Publications and source records attributed to T Tsuda.

At least 631 records · Page 35Linked to original sources
PubMed1983

Effects of cold exposure on gaseous metabolism and body composition in the rat.

1. Exposure of rats to a temperature of 1 degree C resulted in a temporary decline in respiratory quotient to a minimum on the 4th day of exposure, with subsequent recovery. 2. Metabolism stabilized after 4-6 days of cold exposure. 3. Body composition was determined for control rats and rats exposed to 2 or 23 degrees C for 2 weeks. 4. Animals kept at 2 degrees C had a lower fat content than other groups, with a higher iodine value. 5. Mineral content indicated that bone growth continued during cold exposure.

Animals↗
PubMed1983

Purification of small polydisperse circular DNA of eukaryotic cells by use of ATP-dependent deoxyribonuclease.

Small polydisperse circular (spc) DNAs of mouse thymocytes were purified by a procedure involving nitrocellulose column chromatography and the treatment of ATP-dependent DNase, which acts only upon linear DNA molecules. Nitrocellulose column chromatography prior to the enzyme treatment was essential because digestion of linear DNA duplexes by the enzyme was inhibited by the presence of concomitant single-stranded DNAs. Mitochondrial DNAs were eliminated by linearization with XhoI and digestion with ATP-dependent DNase. The size distribution of the purified spc DNA molecules ranged from 0.2 micron to more than 28 micron, with a mean length of 5.4 micron. Circular molecules of more than 0.4 micron long (or 1.2 kb) were free from the contamination of linear DNA fragments and pure enough to be cloned into plasmids.

Animals↗
PubMed1983

Prolymphocytic leukemia with IgM hypogammaglobulinemia.

A case of prolymphocytic leukemia with IgM hypogammaglobulinemia in a 47-year-old man was presented. The leukemic cells possessed Ia-like antigen and receptors for the third component of complement but lacked surface immunoglobulins, cytoplasmic IgM, receptors for sheep red blood cells, or terminal deoxynucleotidyl transferase activity. In vitro immunoglobulin production experiments demonstrated that the leukemic cells did not have the capacity to produce IgM, while patient's T cells were shown to possess helper function on normal B cells to produce immunoglobulins. By these findings, together with the presence of selective IgM hypogammaglobulinemia, it was suggested that the leukemic cells were derived from a B-cell clone of a stage in differentiation and maturation of IgM-forming B-cell spectrum.

Cytoplasm↗
PubMed1983

A potential synergistic effect of donor antigenic extracts and cyclosporine on the prolongation of rat renal allografts.

Administration of five daily doses of 15 mg/kg Cyclosporine on the day before, the day of, and three days after, renal transplantation prolonged the survival of Buffalo (BUF) renal allografts in Wistar-Furth recipients from a mean survival time (MST) of 7.9 +/- 0.74 to 25.5 +/- 1.2 days. The immunologic effects of this brief cyclosporine course were assessed using spleen cells harvested five days after transplantation. Cyclosporine abrogated both the direct lymphocyte-mediated cytolysis of donor 51Cr-labelled BUF targets, and the early, three-day enhanced proliferation, and it stimulated lympholysis of labelled donor cells markedly after restimulation in vitro with BUF lymphocytes. Therefore, cyclosporine disrupts the maturation of both proliferative and cytotoxic precursors of the alloimmune response. A potentially synergistic effect of soluble donor antigen with cyclosporine was postulated, because 3 M KCl extracts are capable of directly stimulating both suppressor T cells and helper T cells. Because the activity of T helper cells appeared in these experiments to be dampened by cyclosporine, antigen stimulation of suppressor cells could lead to unresponsiveness. On the day prior to transplantation, 5 mg of a 3 M KCl extract of BUF spleen (Ag) was administered intravenously in addition to the cyclosporine regimen. Although there was no difference in the overall survival of grafts in the Ag-cyclosporine group and the cyclosporine only group, the Ag-cyclosporine regimen did prolong graft survival significantly in the subset of animals with grafts functioning more than 35 days (Ag-cyclosporine MST = 109.5, cyclosporine alone MST = 54 days). Therefore, it may be possible to exploit the selective properties of cyclosporine and of soluble antigen treatments to achieve unresponsiveness without the hazards of continued administration of immunosuppressive agents.

Animals↗
PubMed1983

Enhanced responsiveness to insulin in sheep exposed to cold.

The effects of cold exposure on tissue sensitivity and responsiveness to insulin were determined by the euglycemic insulin clamp technique. Insulin was infused at rates of 0.2, 0.5, 1.0, 6.0, and 30.0 mU x kg-1 x min-1 into five adult sheep in a warm environment and after cold exposure (0 degree C) from 7 to 23 days. Cold exposure increased basal plasma glucose concentration and basal glucose irreversible loss. Glucose metabolic clearance rate (MCR) was significantly increased by cold exposure at all rates of insulin infusion, with increases ranging from 44 to 72%. The insulin concentration causing half-maximal stimulation of glucose MCR was unchanged by environment (warm, 42 microU/ml; cold, 36 microU/ml). Combined alpha + beta-adrenergic blockade did not affect the increased response to insulin during cold exposure. Endogenous (hepatic) glucose production was inhibited by insulin to a similar extent in the two environments and was less sensitive to insulin than was glucose utilization or MCR. The results suggest that cold exposure increases the responsiveness to insulin of a postreceptor event in peripheral tissues.

Acclimatization↗
PubMed1983

Turnover and oxidation rates of blood glucose and heat production in sheep exposed to heat.

Five shorn sheep were used to study effects of heat exposure (30 degrees C, relative humidity 70%) on metabolism of blood glucose and heat production. The isotope dilution method was applied for determination of metabolism of blood glucose in a thermoneutral environment (20 degrees C, relative humidity 70%) and on the 4th and 10th days of heat exposure. Concentrations of free fatty acids and thyroxine of plasma decreased during heat exposure with no reduction in feed intake. At 20 degrees C, glucose turnover rate, percentage of glucose oxidized, and contribution of exhaled carbon dioxide derived from glucose to the total carbon dioxide production were 6.2 mg/kg.75 per min, 34%, and 11%. Glucose turnover rate decreased significantly during heat exposure, but the proportion of glucose oxidized was unchanged. Heat production decreased almost parallel to the glucose turnover rate during heat exposure, resulting in an unchanged contribution of carbon dioxide derived from glucose to the total production of carbon dioxide. Blood glucose metabolism and heat production of sheep decrease, but the contribution of blood glucose to heat production remains unchanged during exposure to 30 degrees C.

Animals↗
PubMed1983

Membrane phospholipid turnover in signal transduction; protein kinase C and mechanism of action of tumor promoters.

Protein kinase C distributed widely in tissues and organs has the potential to play a crucial role in signal transduction for a variety of biologically active substances including growth factors, which elicit activation of cellular functions and proliferation. When cells are stimulated, this protein kinase is transiently activated by diacylglycerol which is produced in the membrane during the signal-induced turnover of inositol phospholipids. Tumor-promoting phorbol esters are intercalated into the membrane, substitute for diacylglycerol, and permanently activate protein kinase C irrespective of the feedback control by cyclic AMP. Under normal conditions in many tissues this cyclic nucleotide blocks the signal-induced inositol phospholipid breakdown and thereby prevents the activation of this protein kinase. Available evidence suggests that protein kinase C is most likely a receptor protein of tumor promoters, and exploration of the roles of this enzyme may provide clues for understanding better the biochemical basis of cell growth and differentiation.

Animals↗
PubMed1983

[Indium-111-oxine labeled platelet scintigraphy for detection of intracardiac and intravascular thrombi].

This study was designed to evaluate the efficacy of scintigraphy by using 111In-oxine labeled platelets for the detection of either intracardiac or intravascular thrombi. Fourteen cases of thrombi diagnosed or suspected on the basis of either angiography or two-dimensional echography were examined. They included four cases of left ventricular thrombi, three of left atrial thrombi, four of vascular thrombi and three of inflammatory disease. Platelet samples from the patients were labeled by 111In-oxine according to the method originated by Yui et al. The labeling efficiency was 72.4 +/- 9.8%. The platelets retained good function except for collagen aggregability. Hot areas of high quality in the scintigram were demonstrated in six cases including two with left ventricular thrombi, two with left atrial thrombi and two with vascular thrombi. These areas accorded well with the findings of angiography, echography or surgery. The removed thrombi had a layer of aggregated platelets on the surface. Platelet survival was shortened in a case of prosthetic valve endocarditis without a hot area, and was normal in four out of five cases including two with a hot area. It is concluded that this method is potentially predictive in detecting thrombi.

Adult↗
PubMed1983

Gas chromatographic determination of glucono-delta-lactone in foods.

A method is described for the gas chromatographic (GC) determination of glucono-delta-lactone in foods. A sample was homogenized with 60-70 degrees C water and filtered. The filtrate was buffered with NH4OH-NH4Cl pH 10 solution, and was passed through a QAE-Sephadex A25 column. The column was washed with water and glucono-delta-lactone was eluted with 0.1N HCl. An aliquot of the eluate was evaporated to dryness and derivatized with pyridine, N,O-bis(trimethylsilyl)trifluoroacetamide, and trimethylchlorosilane at room temperature. GC separation of glucono-delta-lactone as the TMS derivative was performed on a 2% OV-17 column at 180 degrees C. Recoveries from bread, jelly, soybean curd, and other foods fortified with 0.1% glucono-delta-lactone ranged from 92 to 106%, with standard deviations from 2.2 to 9.8%. The detection limit was approximately 0.025%.

Chromatography, Gas↗