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Biomedical subjects

T Shimada

Publications and source records attributed to T Shimada.

At least 883 records · Page 49Linked to original sources
PubMed1985

Activities of chlorinated ethane and ethylene compounds in the Salmonella/rat microsome mutagenesis and rat hepatocyte/DNA repair assays under vapor phase exposure conditions.

Three chlorinated ethane and ethylene solvent products were examined for their genotoxicity in the Salmonella/microsome mutagenesis and hepatocyte primary culture DNA repair assays using vapor phase exposures. The positive control in this study, monochloroethylene (vinyl chloride), induced reversion mutation of Salmonella tester strains TA100 and TA1535 with enhancement by an exogenous activation system and elicited unscheduled DNA synthesis in rat hepatocytes in culture. Exposures to 1,1,1-trichloroethane (methyl chloroform) or 1,1,2-trichloroethylene samples which contained stabilizers resulted in increased recovery of revertant colonies of Salmonella at concentrations causing greater than 96% cell killing. However, these stabilized materials did not induce DNA repair and low-stabilized trichloroethylene did not induce reversion mutation or DNA repair. Exposure of Salmonella tester strains and hepatocytes to highly toxic vapor concentrations of technical grade 1,1,2,2-tetrochloroethylene, low-stabilized and stabilized, increased reversion mutation and elicited DNA repair. Tetrachloroethylene of high purity was not genotoxic. With all of these test products, the presence of an Aroclor-induced rat liver subcellular enzyme preparation in the mutagenesis assay did not have any effect on the results. These observations suggest that stabilizers or unknown impurities normally present at low concentrations in these products are responsible for the positive responses observed at the high exposure concentrations achievable under in vitro test conditions.

Animals↗
PubMed1985

Interaction of 3,4,3',4'-tetrachlorobiphenyl metabolites formed by cytochrome P-450 in vitro with rat erythrocytes.

Incubation of 14C-labeled 3,4,3',4'-tetrachlorobiphenyl (TCB) with a reconstituted monooxygenase system containing cytochrome P-450 isolated from 3-methylcholanthrene (MC)-treated rats caused an increase in incorporation of radioactivity to added rat erythrocytes and resulted in covalent binding of reactive metabolites to hemoglobin. Both increases in incorporation and covalent binding to the proteins were dependent on incubation time and required cytochrome P-450-linked monooxygenase activity. In the absence of erythrocytes, the reactive TCB metabolites bound to cytochrome P-450, NADPH-cytochrome P-450 reductase, and high-molecular weight aggregates, as determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, whereas inclusion of the cells in the reaction mixture caused marked alkylation of hemoglobin and a decrease in binding to the electron transfer proteins. Several metabolites other than protein-bound metabolites were detected by thin-layer chromatography; some were found to be incorporated into the erythrocytes while others were not. These results suggest that several TCB metabolites formed by cytochrome P-450 can interact with rat erythrocytes in vitro, and that these interactions may be responsible for the persistence of TCB metabolites in blood observed in vivo.

Animals↗
PubMed1985

Activation of factor XII and prekallikrein with polysaccharide sulfates and sulfatides: comparison with kaolin-mediated activation.

The activation of Factor XII and prekallikrein by polysaccharide sulfates and sulfatides in the presence of high-molecular-weight (HMW) kininogen was studied, and compared with the kaolin-mediated activation reaction. Among a variety of artificially-sulfated polysaccharides and native polysaccharide sulfates, amylose sulfate (M.W.= 380,000 and sulfur content, 19.1%) and sulfatide were found to have the most efficient ability to trigger the activation of prekallikrein by Factor XII. The effects of these two kinds of negatively-charged surfaces on the following three activation reactions were compared; the activation of prekallikrein by Factor XII (reaction 1), the activation of Factor XII by kallikrein (reaction 2) and the activation of prekallikrein by Factor XIIa (reaction 3). All three reactions mediated by the selected surfaces were strongly accelerated by HMW kininogen and its derivatives, kinin-free protein and fragment 1.2-linked light chain, like the kaolin-mediated activation. However, this accelerating effect of HMW kininogen on the amylose sulfate- and sulfatide-mediated activations (reaction 1) was diminished after treatment with fluorescein iso-thiocyanate, whereas the effect on the kaolin-mediated activation was not influenced by fluorescein-labeling. In addition, reaction 2 mediated by amylose sulfate and sulfatide was extremely slow even in the presence of HMW kininogen, and the results also differed from those with kaolin. The sulfatide-mediated activation of reaction 1 was not inhibited by fragment 1.2 (His-rich fragment), which is released from HMW kininogen by the action of kallikrein, and is known to be a potent inhibitor of the kaolin-dependent activation. These results indicate that the mechanisms responsible for surface activation triggered by soluble amylose sulfate, sulfatide micelles and kaolin differ from each other as regards the molecular interaction with the contact factors.

Animals↗
PubMed1985

Interaction of factor XII, high-molecular-weight (HMW) kininogen and prekallikrein with sulfatide: analysis by fluorescence polarization.

The interaction of high-molecular-weight (HMW) kininogen, Factor XII and prekallikrein with sulfatide was studied by fluorescence polarization. Fluorescein-conjugated derivatives of HMW kininogen, Factor XII and prekallikrein were prepared by reacting the purified bovine factors with fluorescein isothiocyanate (FITC). The apparent dissociation constant (Kd) for the binding of FITC-labeled HMW kininogen (F-HMW kininogen) with sulfatide was calculated to be 3.2 (+/- 0.3) X 10(-8) M. This binding was partially inhibited by three kininogen derivatives, fragment 1 X 2, kinin-free protein and fragment 1 X 2-light chain, but not by kinin and fragment 1 X 2-free protein. In the presence of Factor XII, the binding of F-HMW kininogen with sulfatide was strongly inhibited, suggesting that the zymogen and the protein cofactor compete for the same or a closely related binding site on the sulfatide surface. In contrast, the binding of FITC-labeled Factor XII (F-Factor XII) with sulfatide was weakly inhibited by HMW kininogen but not by prekallikrein. The Kd value for binding of F-Factor XII with sulfatide was calculated to be 2.0 (+/- 0.3) X 10(-8) M. F-Prekallikrein did not interact with sulfatide. Moreover, the fluorescence polarization value of F-HMW kininogen decreased in the presence of prekallikrein, leveling off at a one-to-one molar ratio of prekallikrein to F-HMW kininogen. The Kd value for binding of F-HMW kininogen-light chain (F-light chain) with prekallikrein was calculated to be 3.8 (+/- 0.6) X 10(-8) M and the stoichiometry was estimated as 1 to 1.2 on a molar basis from the Scatchard plot.

Animals↗
PubMed1985

Light and electron microscopic studies on capillaries of the goat cardiac muscle with special reference to the topographical relationship between the vessels and Purkinje fibers.

The capillaries of the cardiac muscle were investigated in the goat by means of light microscopy, transmission electron microscopy and scanning electron microscopy, and the following results were obtained. The capillaries of the working cardiac muscles were numerous, arranged mainly parallel to the long axis of muscle cells and formed dense elongated networks. On the contrary, those of the terminal Purkinje fibers were relatively few in number, oriented in various directions and formed loose and circularly meshed networks surrounding the fibers. Such findings were discussed in correlation with the physiology and functional morphology of various types of the cardiac muscle cells.

Animals↗
PubMed1985

Effect of monensin on the synthesis, maturation and secretion of vesicular stomatitis virus proteins in a monensin-resistant Chinese hamster ovary cell line.

We compared the effects of the cationic ionophore, monensin, on the synthesis, maturation and release of vesicular stomatitis virus (VSV) in cultures of Chinese hamster ovary (CHO) cells and the monensin-resistant clone, MonR-31. Our results depended on the dose and time of the addition of monensin to the infected cells, from 1 h prior to VSV infection to 1 h after infection. VSV production was more resistant in MonR-31 than in CHO cells when the ionophore was added 1 h prior to VSV infection. Monensin added 1 h after VSV infection showed the opposite phenomenon; release of virus particles into the medium was 10- to 10(5)-fold less in MonR-31 cells than in CHO cells, and the intracellular virus number in the resistant cells was one-third to one-fourth of that in the parental CHO cells. Syntheses of all virus-associated G, N and M proteins were inhibited in both cell lines by monensin, but especially so in the MonR-31 cells. There were no marked qualitative changes in the biochemical properties of viral glycoprotein G in virus-infected CHO and MonR-31 cells treated with monensin after virus infection. An endoglycosidase H-resistant G with a molecular weight smaller than that of normal G and attachments of palmitate or fucose on the truncated G protein appeared. Alteration of the secretion of as well as the synthesis of the enveloped virus is discussed in relation to the monensin susceptibility of the resistant MonR-31 clone.

Animals↗
PubMed1985

Contraction independent of extracellular Ca by sodium vanadate in guinea-pig vas deferens.

The effects of Ca removal and Ca antagonists on sodium vanadate-induced contractions of the guinea-pig vas deferens were studied. Sodium vanadate-induced tension development could be observed even 120 minutes after the removal of Ca, whereas K-contracture disappeared within 20 minutes. Spontaneous contractions induced by sodium vanadate were abolished by the removal of Ca. Verapamil and nifedipine did not show any effect on sodium vanadate-induced contraction, contrastingly, they blocked spontaneous contractions initiated by sodium vanadate. The effects of sodium vanadate on Ca contracture of depolarized preparations were also studied. Though the drug potentiated phasic contraction, it did not potentiate tonic component of Ca contracture. It was demonstrated that sodium vanadate induced tension development independently of extracellular Ca, presumably by releasing intracellularly bound Ca.

Animals↗
PubMed1985

Effects of sodium vanadate on the smooth muscle of the guinea-pig vas deferens.

Effects of sodium vanadate on electrical and mechanical activities of smooth muscle of the guinea-pig vas deferens were investigated. Sodium vanadate of concentrations higher than 5 X 10(-6) M caused an elevation of basal tension and, at concentrations higher than 5 X 10(-4) M, initiated spontaneous contractions. These effects were not blocked by treatments with reserpine, tetrodotoxin or phentolamine. Treatment with ouabain also did not block the tension development by sodium vanadate. Sodium vanadate caused slight depolarization of membrane and potentiated spike activities. The phasic contraction of potassium contracture was potentiated by sodium vanadate in a similar manner to pretreatment with 15 mM K+ or with ouabain, both treatments occasioning slight depolarization. Sodium vanadate also caused tension development in K-depolarized preparetions. Contrastingly, drug-induced contractions were not significantly affected by sodium vanadate. It is suggested that sodium vanadate acts directly on smooth muscles and causes tension development without relation to Na, K-ATPase activity. Changes in the membrane electrical activities may be part of the cause of contraction. However, it can also initiate tension development without membrane potential changes, presumably acting on intracellular Ca binding sites.

Animals↗
PubMed1985

Effect of hydrogen ion-gradient on carrier-mediated transport of glycylglycine across brush border membrane vesicles from rabbit small intestine.

Glycylglycine (Gly-Gly) transport across rabbit small intestinal brush border membrane vesicles was studied in the presence and absence of a Na+ gradient or a pH gradient. The transport was found to be entirely independent of Na+ but significantly stimulated by lowering extravesicular pH (pHo). The maximum stimulation was seen at pHo 5.5, where the uptake rate was about 2-times higher than the control value. FCCP, a protonophore, abolished the stimulating effect of low pHo, and low pHo conditions without a pH gradient did not stimulate the uptake rate. Overshoot uptake of Gly-Gly was observed when a pH gradient of 2 pH units was imposed across the vesicular membrane. Valinomycin-induced inside-negative K+ diffusion potential also had a stimulating effect on the uptake, and fluorescence measurements of vesicular suspensions containing diS-C3-(5) revealed the occurrence of depolarization of the vesicular membranes when Gly-Gly was added to the suspensions. Kinetic study showed that a pH gradient caused a decrease of Kt for Gly-Gly without affecting Vmax. All the data obtained indicate that Gly-Gly transport is independent of Na+, dependent on a H+ gradient, and electrogenic, suggesting the mechanism of cotransport with H+.

Animals↗
PubMed1985

Peritrichous flagella in mesophilic strains of Aeromonas.

A total of 186 mesophilic strains of Aeromonas, comprising 151 A. hydrophila and 35 A. caviae, were tested for peritrichous flagella by Leifson's staining method. When incubated on solid medium for 18 hr at 22 C, peritrichous flagella were demonstrated in 28 (18.5%) of the 151 strains of A. hydrophila and in 6 (17.1%) of the 35 strains of A. caviae. The peritrichous flagella in these 34 mesophilic strains of Aeromonas were also observed by electron microscopy.

Aeromonas↗
PubMed1985

Peroneal island flap for skin defects in the lower extremity.

Two types of peroneal island-flap transfer were used in fourteen patients with a large defect in the soft tissues of the lower extremity. The peroneal artery and vein and their cutaneous branches form the pedicle, and an extensive transfer of skin is possible either from above the knee or from the lateral side of the leg to as far distal as the foot. Two methods were used: in the first we severed the peroneal artery and vein distally, with an island of skin attached, and elevated them proximally, and in the second we severed the proximal portions of the peroneal vessels, with an island of skin attached, and elevated them distally. The largest flap that we used in this series measured fourteen by 16.5 centimeters and the smallest, 2.5 by five centimeters. All fourteen transfers healed, with no necrosis of the flap.

Adult↗
PubMed1985

[Facial nerve neurinoma--report of 2 cases].

Two cases of facial nerve neurinoma (VII-Nm) were reported. The first case is a 41-year-old man who had 16 years of history of slowly progressive right facial palsy and hearing disturbance. The tumor originated in horizontal portion of the right facial nerve, and extended epidurally into the middle cranial fossa, as well as medially along the facial canal to the C-P angle. The second case is a 55-year-old man with 16 years of history of progressive right facial palsy which was followed by hearing disturbance. The tumor was found in the vertical portion of the right facial nerve, expanding in the petrous bone. Both tumors were removed surgically. 116 VII-Nm were reported in the literature including our 2 cases. Most were reported in the ENT field, and only 11 cases in the neurosurgical field. Facial palsy or hearing disturbance is the initial symptom, depending on the site of origin in the facial nerve. VII-Nm can originate in any part of the facial nerve. The most common part of origin is the vertical portion where the tumor tends to expand locally, but it may extend extracranially along the facial canal. The tumor which originates in the tympanic portion tends to extend into the middle ear cavity. The tumor originating in the horizontal portion extends to the epidural space in the middle cranial fossa and/or medially along the facial canal. VII-Nm in the cisternal portion of the facial nerve extends to the posterior cranial fossa and produces the signs of C-P angle tumor. Unlike the acoustic neurinoma, VII-Nm is associated with marked facial palsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗