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Biomedical subjects

N Shibata

Publications and source records attributed to N Shibata.

At least 235 records · Page 13Linked to original sources
PubMed1993

Neurosteroids in cerebrospinal fluid in neurologic disorders.

In order to investigate the role of "neurosteroids" in the central nervous system (CNS), cerebrospinal fluid (CSF) levels of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) were determined by radioimmunoassay in 57 patients with various neurologic disorders and 26 patients with non-neurologic disorders. The content of CSF DHEA and DHEAS in patients with Guillain-Barré syndrome (GBS), and the content of CSF DHEAS in patients with carcinomatous meningitis were significantly higher as compared to non-neurological control patients. These changes may be explained by the breakdown of blood-nerve barrier in these disorders. A significant positive correlation was observed between DHEAS and total protein in CSF. In males but not females, a negative correlation was observed between CSF DHEAS and aging. The level of CSF DHEAS, but not DHEA, was significantly higher in males than in females.

Adult↗
PubMed1993

Altered fibronectin-dependent cell adhesion by PDGF accompanies phenotypic modulation of vascular smooth muscle cells.

PDGF promotes growth of smooth muscle cells (SMCs) and induces morphological changes. We investigated the effects of PDGF on cell-matrix adhesion of SMCs. PDGF reorganized integrin distribution as well as actin filament structure. PDGF-treated cells attached more loosely to fibronectin than non-treated cells. Decreased expression of alpha-actin by PDGF was antagonized by coating culture dishes with fibronectin but not with vitronectin and laminin. The inhibition of cell adhesion by GRGDSP oligopeptide and anti-fibronectin receptor antibody led to the reduction in alpha-actin expression. These results suggest that PDGF may modulate phenotype of SMCs by altering fibronectin-integrin interaction.

Actins↗
PubMed1993

Structural study of a cell-wall mannan of Saccharomyces kluyveri IFO 1685 strain. Presence of a branched side chain and beta-1,2-linkage.

Acetolysis of the cell-wall mannan of Saccharomyces kluyveri under mild conditions, gave fragments with 1-6 mannose residues. The structures of mannopentaose and mannohexaose were determined to be [Formula; see text] respectively, by two-dimensional homonuclear Hartmann-Hahn spectroscopy and a sequential NMR assignment method that combines 1H-13C correlated spectroscopy, relayed coherence transfer spectroscopy, 1H-detected heteronuclear multiple-bond connectivity and methylation analysis. The H1 proton chemical shift of a neighboring alpha-1,2-linked mannose unit of the 3-O-substituted structure was shifted upfield by the addition of a mannose unit to the adjacent 3-O-substituted unit by an alpha-1,6 linkage. The characteristic H1--H2-correlated cross-peak of the alpha-1,3-linked mannose unit substituted by a beta-1,2 linkage, beta 1-->2Man alpha 1-->3, in the mannan of S. kluyveri, as also found by two-dimensional homonuclear Hartmann-Hahn spectroscopy in the mannan of Candida guilliermondii, a pathogenic yeast in man.

Carbohydrate Conformation↗
PubMed1993

Responses of smooth muscle cells to platelet-derived growth factor are inhibited by herbimycin-A tyrosine kinase inhibitor.

Platelet-derived growth factor (PDGF) plays important roles in proliferation of smooth muscle cells (SMCs). PDGF is also known to induce the cytoskeletal reorganization as a chemoattractant. In this communication, we demonstrate that the tyrosine kinase inhibitor herbimycin-A (HM-A) inhibited the effects of PDGF on SMCs in proliferation, phenotypic modulation, and reorganization of F-actin. Another tyrosine kinase inhibitor genistein also inhibited reorganization of F-actin. Since both tyrosine kinase inhibitors reduced PDGF-dependent tyrosine phosphorylation, tyrosine kinase activities may be involved not only in proliferation but also in reorganization of F-actin.

Actins↗
PubMed1993

Complete assignment of 1H and 13C nuclear magnetic resonance chemical shifts of beta-1,2-linked mannooligosaccharides isolated from the phosphomannan of the pathogenic yeast Candida albicans NIH B-792 strain.

To confirm correctness of the previous assignment study of H-1 protons of beta-1,2-linked mannooligosaccharides provided by Shibata et al. (Biochemistry 31, 5680-5686, 1992), another type of nonempirical assignment of the H-1 signals of the same oligosaccharides was achieved by adopting a sequential NMR assignment method that combines two-dimensional 1H-13C correlated spectroscopy, two-dimensional 1H-1H correlated spectroscopy, and two-dimensional heteronuclear multiple-bond connectivity. Based on the above results, all of the 1H and most of the 13C signals in each oligosaccharide could also be assigned. The results of the proton assignment study provided sufficient evidence to confirm the correctness of that obtained in the previous H-1 proton assignment study. Furthermore, the existence of a regularity rule between the order of mannose units and its 1H and 13C chemical shifts has been revealed.

Candida albicans↗
PubMed1993

Levels of complement regulatory molecules in lung cancer: disappearance of the D17 epitope of CD55 in small-cell carcinoma.

The levels of complement-regulatory molecules (complement receptor type one [CR1], decay-accelerating factor [DAF], membrane cofactor protein [MCP], and an inhibitor of membrane attack complex [CD59]) in lung cancer cells were analyzed to investigate the relation between their expression and histological subtypes, and the possibility of homologous complement deposition on cancer cells. In 25 cell lines (10 adenocarcinoma, 3 large-cell carcinoma, 7 small-cell lung cancer [SCLC], and 5 squamous cell carcinoma), flow cytometric analysis revealed that MCP was expressed in all cell lines, whereas none of the cell lines was CR1-positive. CD59 was detected in all cells. The DAF epitope defined by IA10 was expressed in all cells except one large cell carcinoma cell line. However, another epitope for anti-DAF monoclonal antibody, D17, was not detected in 5 (71.4%) SCLC and in 4 (22.2%) non-small-cell lung cancer. This disparity was seen in most cell lines, irrespective of histological subtypes. The loss of D17 reactivity seemed to be pertinent to malignant phenotype, because most of the normal pulmonary cells possessed the D17 epitope. Furthermore, a cell line lacking DAF (IA10-/D17-) allowed alternative pathway-mediated homologous complement (C3) deposition after pretreatment with anti-MCP antibody. This raises a new possibility for immunotargeting of cancer. These cell lines should be useful in studying the biology of lung cancer.

Antigens, CD↗
PubMed1993

Pharmacokinetics of cyclosporin A after intravenous administration to rats in various disease states.

We examine the pharmacokinetic profile of cyclosporin A (CyA) after intravenous administration to rats prepared as models of various disease states found in patients who receive organ transplantations. After intravenous bolus administration to normal rats, the total blood clearance (CLt) of CyA showed a dose-dependent increase. The CLt was reduced in anemic (ANE) rats prepared by venesection, in carbon tetrachloride-induced acute hepatic failure (AHF) rats, and in glycerol-induced acute renal failure (ARF) rats. On the other hand, the volume of distribution at a steady state (Vss) of CyA increased significantly in ANE and aged (AGE) rats. CyA distribution was tissue-specific, and the tissue CyA concentration was disease state-dependent. Linear relationships between the CyA concentration in whole blood and various tissues (liver, kidney and heart) were found in AGE, ANE and AHF animals. However, in ARF rats, tissue concentration was not increased to a great extent in comparison with the other disease models, even though the whole blood CyA concentration was increased. The tissue per blood concentration ratio (Kb), which represented the CyA tissue transfer from systemic circulation, was influenced by the disease state. In the liver, in particular, the Kb increased in the AHF and AGE groups, whereas it decreased in the ANE and ARF rats. The CLt of CyA was negatively related to the erythrocyte per plasma concentration ratio (E/P), and the E/P exhibited disease state-dependent changes, suggesting that this ratio is a valuable indicator for predicting variations in CyA total blood clearance in organ transplant patients during episodes of anemia, nephrotoxicity and hepatotoxicity.

Acute Kidney Injury↗
PubMed1993

Erythrocyte uptake and protein binding of cyclosporin A (CyA) in human blood: factors affecting CyA concentration in erythrocytes.

To further the understanding of the complexity of cyclosporin A (CyA) pharmacokinetics, we conducted an erythrocyte uptake and efflux study, and a protein binding study in human blood. The uptake study showed that the transport of CyA from the extracellular fraction to erythrocytes was retarded by increased human serum albumin (HSA) and lipid levels in this fraction. In addition, the concentration of CyA in erythrocytes increased with increases in CyA concentration in blood and reductions in hematocrit. The efflux study showed that the transport of CyA from erythrocytes to the extracellular fraction was essentially enhanced by increases of HSA and lipid levels in that fraction, but that these effects were relatively small. There were two affinity binding sites for CyA in ghost-free erythrocyte hemolysate, but not in the plasma fraction. The affinity binding constants for these binding sites were reduced by elevations in temperature, and under physiological conditions, 37 degrees C, almost all the CyA in erythrocytes was bound to a CyA binding protein, namely, cyclophillin. These findings suggest that CyA distribution in blood is of two different types which are present in the erythrocyte and plasma fractions, respectively. Monitoring of blood biochemistry variables showed that the concentration of CyA in erythrocytes had an interlocking relationship with these physiological factors, which were related to patient disease state, i.e., hematocrit, lipids, albumin, and total protein; the concentration of CyA in erythrocytes could be predicted from these physiological factors.

Amino Acid Isomerases↗
PubMed1993

Highly purified eicosapentaenoic acid attenuates tissue damage in experimental myocardial infarction.

We examined the effects of dietary supplementation with eicosapentaenoic acid (EPA) on experimental myocardial infarction in dogs. Twenty-five dogs were fed standard diets, 10 of which were supplemented with EPA-ester (100 mg/kg body weight/day) for 8 weeks, while 15 served as controls. After ingesting EPA for 8 weeks, the ratio of EPA to arachidonic acid (AA) in platelet cell membranes significantly increased (from 0.033 to 0.105; p < 0.01). The chemotactic response of neutrophils to leukotriene B4 (LTB4) was reduced in the EPA group (34% reduction at 10(-6) M LTB4, p < 0.01). Also in the EPA group, the amount of 12-hydroxyeicosatetraenoic acid, one of the chemotactic products of AA in infarcted myocardium, was reduced to 40% (p < 0.05). EPA treatment resulted in significant reduction in the ultimate size of the infarcted area. Contractile function of infarcted myocardium was well-preserved in the EPA group. Myeloperoxidase activity, an indication of the infiltration of neutrophils into the infarcted myocardium, was less in the EPA group than in the controls (0.68 +/- 0.25 U/0.1 gr. vs 1.22 +/- 0.55 U/0.1 gr., p < 0.05). Therefore, we conclude that dietary supplementation with EPA attenuates ischemic myocardial damage through inhibition of neutrophilic infiltration into the infarcted myocardium.

Animals↗
PubMed1993

Autoxidation of human hemoglobin: kinetic analysis of the pH-profile.

The autoxidation reaction of human hemoglobin A was studied over the pH range of 5.3-10.4 in 0.1 M buffer at 37 degrees C. In the first-order plot, hemoglobin showed a biphasic reaction, which consisted of a rapid initial reaction and was followed by a slower second phase in the acidic or neutral pH range (5.3-8). However, this difference decreased with increase of pH of the solution and only a single-phase reaction was observed in alkali solutions above pH 8. For the kinetic analysis of the time course of the reaction, computer fitting was made to obtain curves as a function of time by a non-linear least squares method using a biphasic first-order equation with rate constants of kf and ks for the initial fast component reaction and for the slower second reaction, respectively. The parameter of the molar fraction (P) with a rate constant of kf was computed in the range of 0.45-0.55, which means that hemoglobin was autoxidized with half of the component via the reaction process with the initial rapid rate (kf) and the other half via the reaction with the following slower rate (ks). kf and ks thus obtained versus pH plot also indicated that (1) both rate constants increase markedly with increase in hydrogen ion concentrations, but (2) when pH > 8, kf becomes equal to ks with P = 1.0, and (3) there appears a rate minimum at pH 8-8.5, followed by a considerable elevation of the rate with increase in hydroxyl ion concentration. In order to examine these complicated pH-profiles, some mechanistic models were proposed for the autoxidation reaction of hemoglobin. Fitting of their rate equations as a function of pH was examined for the experimental rate constants kf and ks versus pH plot by the least squares method with use of a computer. Both pH-profiles could be best explained by the "acid-base catalyzed model." This revealed not only the catalytic role of hydrogen ions but also the involvement of hydroxyl ions and water molecules in the autoxidation reaction of human hemoglobin.

Hemoglobin A↗
PubMed1993

Lectin-binding glycoconjugates in the tongues of the rat and guinea pig as revealed by lectin-gold-silver methods.

Lectin-gold-silver (LT-G-S) procedures using two lectins (RCA-I and Con A) were applied to appropriately prepared paraffin sections of tongues in the rat and guinea pig. In the lingual mucous membranes of the rat and guinea pig, positive RCA-I-G-S and Con A-G-S reactions were obtained in the intercellular spaces and the cytoplasm of epithelial cells of the basal and intermediate layers respectively. Likewise, the LT (RCA-I and Con A)-G-S techniques gave rise to varying intensities of positive reactions in the serous and mucous gland acini, nerve and muscle fiber bundles and connective tissue elements. The results obtained in the present study indicate that in the rat and guinea pig tongues the histologic structures mentioned contain varying amounts of beta-D-galactose and alpha-D-mannose or alpha-D-glucose residues of glycoconjugates, and that such histochemical properties of some of the lingual structures can be correlated with their possible histophysiological functions.

Animals↗
PubMed1992

Diphosphorylation of platelet myosin ex vivo in the initial phase of activation by thrombin.

We prepared anti-platelet 20-kDa myosin light chain (MLC-20) antibody and demonstrated diphosphorylation of MLC-20 in platelets ex vivo in the initial phase of activation by thrombin. Our results are as follows. (1) By Western blotting, using anti-MLC-20 antibody, both mono- and diphosphorylated myosin were seen in the initial phase of aggregation of platelets by thrombin. The peak of the diphosphorylation was later than that of monophosphorylation and the degree of both mono- and diphosphorylation reduced in the process of aggregation. (2) ML-7 (a synthetic inhibitor of MLCK) inhibited both mono- and diphosphorylation of myosin and also blocked aggregation of thrombin-activated platelets. However, H-7 (an inhibitor of protein kinase C) had little effect on either the (di)phosphorylation of myosin or the aggregation of thrombin-activated platelets. (3) Arg-Gly-Asp-Ser (RGDS) peptide, a synthetic anti-adhesive peptide, inhibited aggregation of thrombin-activated platelets in a dose-dependent manner (100-200 microM). However, it had little effect on either mono- or diphosphorylation of myosin in the process of the platelet aggregation stimulated by thrombin. From these results, we conclude that mono- and diphosphorylation of myosin by MLCK play a role in the initial phase of activation of thrombin-stimulated platelets in vivo and that mono- and diphosphorylation of myosin by MLCK precedes the secondary signal mediated by GPIIb/IIIa.

Azepines↗
PubMed1992

Structure of the D-mannan of the pathogenic yeast, Candida stellatoidea ATCC 20408 (type II) strain, in comparison with that of C. stellatoidea ATCC 36232 (type I) strain.

Acid treatment of the cell-wall D-mannas of Candida stellatoidea strains ATCC 36232 (Type I, A3 strain) and ATCC 20408 (Type II, A2 strain) gave (1----2)-linked beta-D-manno-oligosaccharides (dp 2-5), whereas treatment with alkali gave the (1----2)-linked alpha-D-mannobiose. Conventional acetolysis of the acid- and alkali-treated D-mannan of the A3 strain gave oligosaccharides consisting of (1----2)- and (1----3)-linked alpha-D-mannopyranose residues, similar to those of Candida albicans serotype B strain. Mild acetolysis of the acid- and alkali-treated D-mannan of the A2 strain gave higher oligosaccharides that were digested by the Arthrobacter GJM-1 strain exo-alpha-D-mannosidase. The results of 1H- and 13C-NMR analyses indicated this D-mannan to contain branches with the following structures: beta-D-Manp-(1----2)-alpha-D-Manp-(1----2)-alpha-D-Manp++ +-(1----2)-alpha-D-Manp- (1----2)-D-Man, beta-D-Manp-(1----2)-beta-D-Manp-(1----2)-alpha-D-Manp -(1----2)- alpha-D-Manp-(1----2)-D-Man, and beta-D-Manp-(1----2)-beta-D-Manp-(1----2)-beta- D-Manp-(1----2)-alpha-D-Manp-(1----2)-alpha-D-Manp-(1- ---2)-alpha-D-Manp- (1----2)-D-Man, in common with the D-mannans of C. albicans serotype A strains.

Agglutination Tests↗
PubMed1992

Sequential nuclear magnetic resonance assignment of beta-1,2-linked mannooligosaccharides isolated from the phosphomannan of the pathogenic yeast Candida albicans NIH B-792 strain.

The H-1 and H-2 signals of beta-1,2-linked mannooligosaccharides isolated from the phosphomannan of Candida albicans NIH B-792 strain by mild acid hydrolysis were assigned by a sequential NMR assignment method that combines two-dimensional 1H-1H correlated spectroscopy (COSY) and two-dimensional nuclear Overhauser enhancement and exchange spectroscopy (NOESY). The results indicated that the H-1 and H-2 of each beta-1,2-linked mannopyranose unit show largely different signals compared with those of the alpha-linked ones and that the correlation between linkages and signals could not be explained by a conventional additivity rule. Furthermore, a regular proportional downfield shift of the H-1 signal was observed in the order of the mannose unit from the reducing terminal except those of the reducing and nonreducing terminal positions. Although the 1H NMR spectra of these oligosaccharides were complicated due to the presence of a large portion of the beta-anomer from the reducing terminal mannose unit, reduction of the oligosaccharides with NaBH4 to the corresponding alcohols gave simple and more readily interpretable 1H NMR spectra. Unexpectedly, however, a shift of H-1 signals by this reduction occurred not only on the second mannose unit but also on the third and fourth mannose units from the modified reducing terminal group of each oligosaccharide alcohol. This result indicates that the reducing terminal mannose unit is able to affect up to the fourth mannose unit from the reducing terminal. The presence of a long-distance interresidue NOE also suggests that the beta-1,2-linked mannooligosaccharides have a compactly folded conformation in solution.

Alcohols↗