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H Yuasa

Publications and source records attributed to H Yuasa.

At least 289 records · Page 16Linked to original sources
PubMed1985

[Threshold of penicillin induced epileptiform afterdischarge in brain slices of guinea pig].

Investigation of the regional threshold for epilepsy in many structures in the brain would contribute to the study of epileptogenesis. So we studied the threshold for epileptiform afterdischarge in the neocortex, hippocampus and cerebellar cortex using Na-Penicillin -G (Pc) of which epileptogenesis has been intensively investigated. In order to eliminate the influence from the outside of these structures, the brain slice method was utilized. Procedures for preparation of the tissue and incubation were about the same as those described by Yamamoto. In summary, after sacrifice, brain of the guinea pig was taken out and the hippocampus, neocortex and cerebellum were cut with a razor blade under a microscope. The thickness of the section was about 0.3 mm. Slices were incubated at 37 degrees C for about 30 min in the standard medium perfused with 95% O2 and 0% CO2. The chamber was continuously perfused with the standard medium which composed of NaCl, 124 mM, KCl, 5: KH2PO4, 1.24; MgSO4, 1.3; CaCl2, 2.4; NaHCO3, 26; and glucose, 10. Evoked potentials were elicited by electrical stimulation in the standard medium. Mossy fibers were stimulated and responses were recorded from the CA3 area in the hippocampus by glass pipette microelectrode. Subcortical white matter was stimulated and responses were recorded from the Purkinje cell layer in the cerebellum. Pc was added in the standard medium until epileptiform afterdischarges were superimposed on the evoked potentials. The results of this experiment demonstrated that each structure in the brain has a regional own threshold for Pc induced epileptiform afterdischarge.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

A laminar flow absorption model for a carrier-mediated transport in the intestinal tract.

A laminar flow absorption model for a carrier-mediated transport was developed to analyze the data of the intestinal single perfusion experiment. By using this model, we calculated the absorption rate and the concentration of the substance (drug) at the aqueous-intestinal membrane interface (cwall). The absorption rate was smaller than that predicted by the Michaelis Menten equation, using the concentration at the inlet (c0). The apparent Michaelis constant (Km,app) was larger than the true Michaelis constant (Km), if the data were analyzed by using the simulation curve of the absorption rate vs. c0 as the usual method. This is because cwall was smaller than c0. But the maximal transport velocity (Vmax) was little affected, because cwall became almost equal to c0 when c0 was high. By using this model, we can determine the values of Vmax and Km which are not biased by the unstirred water layer in the intestinal tract.

Biological Transport↗
PubMed1984

Two distinct antigen systems in human B lymphocytes: identification of cell surface and intracellular antigens using monoclonal antibodies.

Two distinct antigen systems (L26 and L27) specifically expressed in human B lymphocytes were identified using TB2-2B3 (2B3) and T3-5B3 (5B3) monoclonal antibodies, respectively. Whereas L26 antigen defined by 2B3 were rarely expressed on the surface of B cells but abundant in the cytoplasm, 127 antigens detected by 5B3 was clearly expressed on the cell surface. These two antigens appeared to be restricted in their expression to B cells, as they were found in most B cells but not other cell types including thymocytes, T cells, monocytes and granulocytes. Functional studies demonstrated that L27 was more easily lost from B cells after activation with pokeweed mitogen than was L26. Likewise, plasma cell myeloma, as well as normal plasma cells, was devoid of both L26 and L27, whereas immunoblastic sarcoma of B cell type expressed L26 but not L27. These two antigens co-existed in the same B cell lines including Epstein-Barr virus transformed B cell lines, B cell type acute lymphatic leukaemia (B-ALL) cell line, Burkitt's lymphoma cell lines and myeloma cell lines, but pre-B and common ALL cell lines were entirely negative for both L26 and L27. Immunoprecipitation studies showed that L26 consisted of at least two polypeptide chains with molecular weights of 30K and 33K daltons, which were clearly distinct from HLA-DR antigens. The antigen L27 is presently under study.

Antibodies, Monoclonal↗
PubMed1984

[Estracyt (estradiol-nitrogen mustard complex)--estramustine binding protein and its specificity].

Estracyt (estramustine phosphate) is a nitrogen mustard derivative of estradiol-17 beta which is rapidly dephosphorylated to yield estramustine. Estramustine is metabolized to estromustine mainly in the liver. Both estramustine and estromustine are retained in rat prostate with a high degree of specificity. This retention is due to the binding of estramustine and/or estromustine to a protein called EMBP (estramustine binding protein). When estimated by HPLC, the molecular weights of these estramustine binding components in rat prostate are 45,000-50,000 and 25,000-30,000, respectively. HPLC and glycerol density gradient analysis clearly demonstrated the occurrence of EMBP in a cytosol preparation from human prostatic cancer tissue. When estimated by HPLC, the molecular weights of estramustine binding components are 45,000 and 25,000 daltons, respectively. In addition, results of effectiveness of Estracyt studied under a cooperative research group in Japan, are reported in this paper. Effectiveness was evaluated at 3 months of the treatment on 121 patients with untreated prostatic cancer (Study I) and 95 patients with reactivated cancer (Study II), at 12 months of the treatment on 68 patients in Study I and 85 patients in Study II, and at 24 months on 37 patients in Study I and 23 patients in Study II. At 3 months of the treatment, Estracyt was effective in 89% of untreated prostatic cancers, and 38% of reactivated prostatic cancers. At 24 months of the treatment, this drug was effective in 65% of untreated prostatic cancers and 30% of reactivated ones. Estracyt is especially recommended as a first-choice drug for both the untreated patients with poorly differentiated adenocarcinoma and reactivated cancer.

Animals↗
PubMed1984

Rat T lymphocyte antigens comparable with mouse Lyt-1 and Lyt-2,3 antigenic systems: characterization by monoclonal antibodies.

Rat T lymphocyte antigens were defined by using two distinct monoclonal antibodies (R1-3B3 and R1-10B5). R1-3B3 antibody, when tested for its reactivity with rat lymphoid cells by immunofluorescence, stained almost all of thymus and T cells but not the majority of B cells and bone marrow cells. The antigen defined by R1-3B3 existed more abundantly on medullary thymocytes and peripheral T cells than on cortical thymocytes. Immunochemical data showed that R1-3B3 antibody recognized a single glycoprotein with a m.w. of 67,000, showing marked electric charge heterogeneity with isoelectric points ranging from 5.4 to 7.3. R1-10B5 antibody, on the other hand, had more restricted reactivity with rat T cells and labeled approximately 85% of thymus cells and 30% of the peripheral T cells but neither B cells nor bone marrow cells. These T cells positive for R1-10B5 appeared to be negative for W3/25 antigen, which has been shown to be the marker for the rat T cell subset associated with helper function. R1-10B5 antibody detected a basic glycoprotein complex consisting of sulfhydryl-linked subunits with 30,000 and 34,000 m.w. Although the antigen defined by R1-3B3 was resistant to trypsin digestion, the one detected by R1-10B5 was much more sensitive to trypsin cleavage. All of these data obtained with either R1-3B3 or R1-10B5 are quite comparable to those reported for mouse Lyt-1 or Lyt-2,3 antigens, and thus suggest that the antigens defined by R1-3B3 and R1-10B5 antibodies represent rat homologues of Lyt-1 and Lyt-2,3 antigens in the murine system, respectively.

Animals↗
PubMed1984

[Penicillin induced epileptiform activity in hippocampal slice--comparison between CA 3 pyramidal cell and granule cell].

To investigate whether a different type of neurons has a different susceptibility to a drug in producing epileptiform activity, we compared penicillin induced epileptiform activities of the two types of neurons in the hippocampal formation of guinea pigs, i.e. the CA 3 pyramidal cells in the hippocampus proper and the granule cells in the dentate gyrus, using slice preparations. The thin slice of 0.4 mm thickness was cut nearly perpendicularly to the longitudinal axis of the hippocampus and was transferred to a nylon mesh in an observation chamber which was perfused with the oxygenated and warmed medium at a rate of 2 ml/min. Under tenfold magnification stimuli were delivered to the nerve fiber layer through bipolar electrodes and evoked field potentials were recorded from the cell body layer with glass micropipettes of 10 mu tip diameter filled with normal medium. In both cell body layers no epileptiform field potentials could be induced during perfusion of normal medium even if stimulus strength was increased. The CA 3 pyramidal cell body layer showed a delayed multipeaked field potential in response to threshold stimulus applied to the mossy fiber in penicillin-containing medium (Pc concentration = 500, 1000, 2000 I. U./ml). When the strength of stimulation increased, the latency shortened, but the amplitude and the duration of epileptiform activity did not change. The granule cell body layer generated no epileptiform activity in response to weak electrical stimulus applied to the perforant path in penicillin-containing medium (Pc concentration = 500, 1000, 2000 I. U./ml). However, at high penicillin concentrations (1000, 2000 I. U./ml) multiple population spikes having a short latency appeared on intense stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1983

Two distinct antigenic markers for rat thymus and T cells defined by monoclonal antibodies.

Rat thymus and T-cell antigens were defined by using two distinct monoclonal antibodies (R-1-3B3 and R-1-12C5). R-1-3B3 antibody, when tested for its reactivity with rat lymphoid cells by immunofluorescence, labelled virtually all thymus and T cells but not B cells and bone marrow cells. The antigen defined by this R-1-3B3 antibody occurred more abundantly on medullary thymocytes and peripheral T cells than on cortical thymocytes. Immunochemical data showed that R-1-3B3 antibody recognized a single glycoprotein with a molecular weight of 67,000, which were able to interact with Lens culinaris haemagglutinin. R-1-12C5 antibody, on the other hand, reacted with all of thymus and T cells as well as with a subpopulation (approximately 20%) of bone marrow cells. In contrast to the antigen defined by R-1-3B3, that detected by R-1-12C5 antibody existed largely on cortical thymocytes and to a much lesser extent on medullary thymocytes and peripheral T cells. R-1-12C5 antibody detected a single glycoprotein with a 95,000 molecular weight, which could also interact with Lens culinaris haemagglutinin. Based on these data described above and since both antigens defined by R-1-3B3 and R-1-12C5 antibodies were absent from rat brain tissue, we concluded that they were distinct from brain-associated thymic antigens in rats including Thy-1 and W3/13 antigen systems.

Animals↗