Biomedical subjects

K Taniguchi

Publications and source records attributed to K Taniguchi.

At least 757 records · Page 42Linked to original sources

PubMed1986

Differential effects of manganese and magnesium on two types of slowly adapting cutaneous mechanoreceptor afferent units in frogs.

While perfusing a frog leg with various solutions, the mechanical responsiveness of slowly adapting (SA) cutaneous mechanoreceptor afferent units innervating the plantar surface of the hindfoot was examined. Perfusion with normal Ringer solutions enhanced the mechanical responsiveness of two types of the SA units, irregularly discharging Frog type I units and regularly discharging Frog type II units, in comparison with that by normal blood supply. On the other hand, when the perfusion was made with Ringer solutions containing Ca blockers, i.e., Mn and Mg, the response magnitudes of both units were reversibly and dose-dependently decreased. Ringer solutions containing 3 mM Mn or 20 mM Mg almost abolished the maintained responses of the Frog type I units to ramp stimulation of the skin, while Ringer solutions of 10 mM Mn significantly decreased those of the Frog type II units. It is suggested that Ca in the medium is a prerequisite to mechanoelectric transduction and the spike generation process at the terminal regions of these slowly adapting cutaneous mechanoreceptor afferent units. Findings that the Frog type I units were quantitatively more sensitive to these Ca blockers than the Frog type II units suggest that an additional process of higher Ca-sensitivity, e.g., chemical synaptic transmission, may be involved on the way from mechanoelectric transduction to the spike generation of the Frog type I units.

Afferent Pathways↗

PubMed1986

Reactivity patterns to human rotavirus strains of a monoclonal antibody against VP2, a component of the inner capsid of rotavirus. Brief report.

A non-neutralizing monoclonal antibody (YO-60) against human rotavirus was found to be directed to VP2 (90,000-dalton protein), one of the two major components of the inner capsid. The reactivity patterns of the YO-60 antibody were very similar, though not identical, to those of subgroup II-specific YO-5 monoclonal antibody directed to VP6 (42,000-dalton protein), the other major component of the inner capsid. These results indicated the possible presence of a subgroup-specific antigen on VP2 in addition to the one on VP6.

Antibodies, Monoclonal↗

PubMed1986

Radiographic microstructures of early esophageal carcinoma: correlation of specimen radiography with pathologic findings and clinical radiography.

To clarify the exact radiologic features of mucosal carcinoma of the esophagus with a favorable prognosis, contact radiography was performed on 8 surgical specimens diagnosed preoperatively as showing early or superficial carcinoma. Mucosal carcinoma appeared as a well-defined smooth or nodular protrusion or as a feathered flat mucosa with tiny nodulations and barium poolings. Submucosal carcinoma showed a mound-like defect. The size of tumor was not a good index for estimating the depth of invasion. Protruded lesions were easily demonstrated on clinical radiographs and their profile was useful in determining the depth of invasion. Flat lesions were not easy to recognize; attention must therefore be paid not only to mucosal patterns but also to the contour of the esophageal wall.

Aged↗

PubMed1986

Indomethacin-induced sialic acid-mediated changes in surface markers from "cortical type" to "medullary type" in murine thymoma line EL-4.

The effect of indomethacin (INDO), a specific inhibitor of prostaglandin (PG) synthesis, on the expression of markers during thymocyte differentiation such as Thy-1, H-2K, and peanut agglutinin (PNA) receptor was examined by immunofluorescence, using poorly differentiated thymoma, EL-4, as the indicator cells. EL-4 cells grown in the culture medium in the presence of INDO exhibited lower levels of Thy-1 and PNA, and a higher level of H-2K, compared with the EL-4 cells grown in medium without INDO. The decrease in PNA level by INDO was attributed to an increased density of sialic acid bound to PNA receptors on the cell surface, because treatment with neuraminidase (Nase) released more sialic acid from such cells, as compared with control cells, and markedly increased the detectable amounts of PNA receptors. On the other hand, a decrease of Thy-1 or an increase of H-2K may be ascribed to the decrease of Nase-resistant sialic acid on the cell surface, determined by analyses with FITC-LPA, sialic acid-specific lectin, and by metabolic labeling of surface sialic acid. These results suggest that the PG-system modulates the metabolism of sialic acid located on the thymocyte surface and alters the expression of surface markers of thymocytes.

Animals↗

PubMed1986

T-cell recruitment from the thymus to the spleen in tumor-bearing mice. II. Functional characteristics of recruited T-cells.

The effect of prostaglandin E2 (PGE2) on characteristics of splenic T-cells in tumor-bearing mice (TBM) was studied from the viewpoint of PGE2-mediated cell-recruitment system from the thymus to the spleen. The splenic T-cells of TBM enhanced tumor growth. In the TBM, the total number of thymocytes decreased, and the number of splenic T-cells concurrently increased. In adult thymectomized tumor bearers, these tumor growth-enhancing T-cells were absent in the spleen, and the number of splenic T-cells remained unchanged. Such suppressor T-cells in the spleens of TBM may relate to recruitment of immature T-cells from the thymus. The levels of PGE2 in the plasma were depressed in the TBM. Replenishment by exogenous PGE2 prevented both an increase in splenic T-cell population and an augmented generation of T-cells that had an enhancing effect on tumor growth. Our findings show that a low level of PGE2 induced the T-cell recruitment from the thymus to the spleen and that such recruited cells led to an acceleration of tumor growth.

Animals↗

PubMed1986

Acceleration of the rate of fluorescence decrease by high concentrations of ATP under the condition of accumulation of ADP-sensitive phosphoenzyme in Na+,K+-ATPase.

Addition of up to 300 microM ATP in the presence of 2 M NaCl with MgCl2 to pig kidney Na+,K+-ATPase treated with N-[p-(2-benzimidazolyl)phenyl]maleimide seemed to be insufficient to saturate the rate of the fluorescence decrease. However, both the extent of the decrease and the amount of phosphoenzyme at a steady state were saturated below 20 microM ATP. Addition of Mg2+ with Na+ to the enzyme preincubated with 20 to 600 microM ATP gave nearly the same rate constant, which was below 50% of that obtained by adding 300 microM ATP to the Na+-form enzyme in the presence of Mg2+. High concentrations of ATP affected neither the rate of light-scattering change (Taniguchi, K. et al. (1986) J. Biol. Chem. 261, 3272-3281) after ADP-sensitive phosphoenzyme formation (E1P) nor that of the breakdown of E1P. A stoichiometric amount of [32P]Pi was liberated from [32P]E1P. The data suggested that ATP did not bind to E1P in such a way as to increase the extent of phosphorylation further or to accelerate dephosphorylation. The data also suggested that the reason for the large difference in the apparent affinity of ATP as evaluated from the rate and the extent of fluorescence change is the large dissociation constant for ATP of a Michaelis complex.

Adenosine Diphosphate↗

PubMed1986

Drug-induced in vitro tolerance to allogeneic antigens. I. Establishment of a tolerance induction system in a fully allogeneic murine combination.

C3H/HeSlc (H-2k) spleen cells were cultured with mitomycin C (MMC)-treated C57BL/6CrSlc (H-2b) spleen cells for 2 days and incubated with 5-fluorouracil (5-FU) for a further 9 hr. Thereafter, those C3H/He spleen cells were recultured with the same allogeneic cells for 5 days. Cell-mediated cytotoxicity (CMC) and mixed lymphocyte reaction (MLR) were profoundly suppressed, antigen-specifically, in such C3H/He spleen cells. In contrast, interleukin 2(IL-2) production was not impaired in the restimulating mixed lymphocyte culture (MLC) with C57BL/6. Moreover, an adequate amount of exogenous IL-2 added to the restimulating MLC did not lead to a restoration of the depressed CMC. Suppressor cell activity in the CMC assay was not detected in the C3H/He spleen cells exposed to such a tolerance induction. These results suggest that the unresponsiveness to alloantigens in CMC and MLR was induced through a clonal deletion mechanism, and there may exist a 5-FU-resistant--thus less-proliferative--cell population that can produce IL-2 even after the tolerance induction.

Animals↗

PubMed1986

Genetic reassortment between two human rotaviruses having different serotype and subgroup specificities.

Two reassortant viruses were selected from a mixed infection of MA104 cells with human rotavirus strains Wa (serotype 1-subgroup II) and HN126 (serotype 2-subgroup I). Antigenic characterization and genotype analysis by polyacrylamide gel electrophoresis revealed that they were reassortants with novel antigenic compositions, i.e. serotype 1-subgroup I (C116) and serotype 2-subgroup II (C15). Furthermore one of them, C15, was considered to have a mosaic antigenicity defined by two serotype-specific antigens, namely the serotype 1-specific VP3 antigen and the serotype 2-specific VP7 antigen. Although this reassortant was shown to be a serotype 2 virus on the basis of its preferential reactivity in neutralization reactions with serotype 2 antiserum, unexpectedly the antiserum prepared against C15 equally neutralized both serotype 1 and serotype 2 strains.

Antigens, Viral↗

PubMed1986

Thymus-dependent increase in splenic T cell population in postpartum mice.

Cell dynamics in the thymus and spleen of mice during the first allogeneic pregnancy and during postpartum were investigated. A considerable decrease in the number of thymocytes occurred at midpregnancy and was sustained until postpartum. There was an increase in the number of splenic T cells on the third postpartum day. These splenic T cells were shown to have the Lyt-1+ 2-phenotype, as determined by multiparameter analysis, and their responsiveness to Con A was increased compared with splenic T cells of virgin mice. Since such T cells were not observed in the postpartum spleen of adult thymectomized mice, they may have derived from the thymus. The response to Con A by normal virgin spleen cells was depressed when spleen cells from 3-day postpartum mice were added to the culture as the third party cells. Thus, the increased number of splenic T cells may act as inducer cells in the suppressor circuit during postpartum.

Animals↗

PubMed1986

Actuarial analysis of reoperation in patients undergoing open mitral commissurotomy for mitral stenosis.

Reoperation is one of the most seriously problematical events in postoperative follow-up of patients undergoing open mitral commissurotomy (OMC) for mitral stenosis. In 217 patients with pure mitral stenosis, even when associated with severe subvalvular changes, the actuarial rate of freedom from reoperation was 94% 12 years after OMC. In contrast, in 85 patients with MS combined with regurgitation, the rate was 66%. In postoperative management of patients undergoing OMC, it is mandatory to know preoperative anatomical findings of the stenosed mitral valve.

Actuarial Analysis↗

PubMed1986

Pharmacological studies on the TXA2 synthetase inhibitor (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoic acid (OKY-046).

The effects of (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoic acid (OKY-046) on thromboxane A2 (TXA2) synthetase in vitro and on experimental animal models of sudden death and cerebral infarction were studied. IC50 values of OKY-046 for the TXA2 synthetase of human, rabbit, dog and guinea pig washed platelets were 0.004, 0.004, 0.26 and 2.4 microM, respectively. OKY-046 at concentrations up to 1 mM, however, did not inhibit prostacyclin (PGI2) synthetase from bovine aorta microsomes or cyclooxygenase and PGE2 isomerase from sheep seminal vesicle microsomes. Similarly, platelet 12-lipoxygenase was not affected by OKY-046. Evidence for a re-direction of arachidonate metabolism from thromboxane synthesis toward PGI2 synthesis was obtained using rat peritoneal cells. Namely, OKY-046 increased PGI2 production accompanied by an inhibition of TXA2 production at a concentration of more than 1 microM. OKY-046 at a dose of 0.1 mg/kg (i.v.) in dogs inhibited the aortic and mesenteric arterial contraction of rabbit induced by the addition of arachidonate to extracorporated blood of the dogs. OKY-046 at a dose of 0.3 mg/kg (i.v.) prevented the arachidonate-induced sudden death and also decreased the incidence of cerebral infarction induced by injection of arachidonate into the internal carotid artery in rabbits. Aspirin also decreased the incidence of cerebral infarction at a dose of 30 mg/kg (i.v.). These results suggest that OKY-046 may be valuable for the treatment of cerebrovascular and cardiovascular diseases associated with vasoconstriction and thrombosis due to TXA2.

Acrylates↗

PubMed1986