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Biomedical subjects

N Shibata

Publications and source records attributed to N Shibata.

At least 307 records · Page 17Linked to original sources
PubMed1987

Caldesmon specifically inhibits the effect of tropomyosin on actomyosin system in platelet.

Caldesmon, a calmodulin and actin binding protein, has been shown to exist in platelet. In this report, it is shown that caldesmon specifically inhibits the effect of tropomyosin to enhance the actomyosin ATPase activity in platelet. Platelet tropomyosin enhances the MgATPase activity of platelet actomyosin. This effect is abolished by platelet caldesmon. In the absence of tropomyosin, however, caldesmon has no effect on the ATPase activity. The inhibition is not due to displacement of the binding of tropomyosin to F-actin by caldesmon. The result indicates that caldesmon is the specific inhibitor of tropomyosin in resting platelet.

Actins↗
PubMed1987

Plasma monoaminergic metabolites and catecholamines in subarachnoid hemorrhage. Clinical implications.

We examined plasma catecholamines and monoaminergic metabolites (3-methoxy-4-hydroxyphenylethyleneglycol [MHPG], homovanillic acid [HVA], and 5-hydroxyindoleacetic acid) in patients with stroke successively up to three weeks after the initiation of symptoms. Plasma levels of free catecholamines were significantly elevated in patients with subarachnoid hemorrhage (SAH). However, no significant differences in plasma catecholamines were found when the patients with SAH were subdivided into noncomatose and comatose groups. In contrast, plasma HVA, MHPG, and 5-hydroxyindoleacetic acid levels in comatose patients with SAH significantly increased as compared not only with normal controls but also with noncomatose patients with SAH, and the peak levels of HVA and MHPG occurred within seven days poststroke. Such trends as observed in SAH were not observed in patients with cerebral hemorrhage. Our results suggest the usefulness of plasma monitoring of possibly centrally originating monoaminergic metabolites for predicting the degree of cerebral dysfunction in patients with SAH.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Structural study of phosphomannan-protein complex of Citeromyces matritensis containing beta-1,2 linkage. Application of partial acid degradation and acetolysis techniques under mild conditions.

The phosphomannan-protein complex of Citeromyces matritensis IFO 0651 strain was investigated for its chemical structure by a sequential degradation procedure, partial acid degradation followed by acetolysis under mild conditions. Upon treatment with 10 mM HCl at 100 degrees C for 1 h, this complex released mannotriose and mannotetraose consisting solely of 1,2-linked beta-D-mannopyranosyl residues, ca. 20% on weight basis of the parent complex. The acid-degraded complex was then subjected to acetolysis using an acetolysis medium of low sulfuric acid concentration, a 100:100:1 (v/v) mixture of acetic anhydride, acetic acid, and sulfuric acid at 40 degrees C for 36 h. A phosphate-containing manno-oligosaccharide fraction eluted in the void-volume region of a Bio-Gel P-2 column was found to consist of Manp beta 1----2Manp beta 1----2Manp alpha 1----2Man to which 1 mol of phosphate group was attached, while a manno-oligosaccharide fraction eluted in the diffusable region was a mixture of Manp beta 1----2Manp beta 1----2Manp beta 1----2Manp alpha 1----2Man, Manp beta 1----2Manp beta 1----2Manp alpha 1----2Man, Manp beta 1----2Manp alpha 1----2Man, Manp alpha 1----2Man, and mannose in the molar ratio of 0.08:0.33:0.19:0.32:1.00. Therefore, the structural analysis of the polysaccharide moiety of a beta-1,2 linkage-containing phosphomannan-protein complex of fungal origin can be achieved by means of a sequential degradation procedure, partial acid degradation followed by acetolysis under mild conditions.

Acetone↗
PubMed1987

Purification of caldesmon and myosin light chain (MLC) kinase from arterial smooth muscle: comparisons with gizzard caldesmon and MLC kinase.

We have developed a simple and conventional purification method for caldesmon and MLC kinase from bovine arterial smooth muscle, and compared the arterial and gizzard proteins. Arterial caldesmon shares the alternative binding to calmodulin or F-actin in a Ca2+-dependent manner and the antigenic determinants with the gizzard protein. Both caldesmons have the same association constant with F-actin (1.3-1.7 X 10(7) M-1) and the same maximum binding (1 caldesmon per 12-14 actins). However, the molecular weight of arterial caldesmon (dimer of a 148 kDa polypeptides) was slightly different from that of gizzard caldesmon (heterodimer of 150/147 kDa polypeptides). The molecular weight of arterial MLC kinase (160 kDa) was much larger than that of the gizzard enzyme (135 kDa). The enzyme activities of both MLC kinases were comparable (Km = 9.5 microM, Vmax = 12.5 mumol/min X mg). The association constant of the arterial enzyme to F-actin (5.1 X 10(6) M-1) was much larger than that of the gizzard enzyme (9.0 X 10(5) M-1) but the maximum binding was the same (1 enzyme per 12-13 actins). Immunocytochemical examinations showed that caldesmon and MLC kinase in cultured arterial cells have a restricted localization along the stress fibers, suggesting functional linkages between both proteins and actin filaments in vivo.

Animals↗
PubMed1987

Quantitative determination of cyclosporin A in whole blood and plasma by high performance liquid chromatography.

A simple, specific and sensitive method for monitoring therapeutic levels of the immunosuppressive agent cyclosporin A (CyA) in whole blood and plasma has been developed which uses a high performance liquid chromatography and involves a simple liquid-liquid extraction procedure. Samples were delipolysed with 0.1 mM dextran sulfate sodium salt, extracted with n-hexane, and chromatographed on a Lichrosorb Si-60 column with UV detection at 215 nm. Each of CyA and internal standard (cyclosporin D) is resoluted clearly as a single peak and no interfering peaks are observed on the chromatograms. The detection limit is 5 ng/ml in whole blood and plasma. The reproducibility assessed by repeated analysis is satisfactory, that is to say, each coefficient of variation of the within-run and between-run precision is below 4%. The analytical recovery of added CyA is almost complete. This method is sensitive enough for monitoring whole blood and plasma levels of CyA in renal transplant patients in the therapeutic dose range, and is also applicable to the study on the distribution of CyA between plasma and non-plasma fractions of blood in patients with renal allografts.

Adolescent↗
PubMed1987

Participation of peptide moieties in adhesive behavior of antigenic mannans of Candida albicans to the plastic microtiter plate in enzyme-linked immunosorbent assay.

We report our studies of the mechanism of the adhesion of mannans of Candida albicans NIH A-207 and C. albicans NIH B-792 strains to the surface of a polystyrene microtiter plate being utilized for enzyme-linked immunosorbent assay (EIA) of antigens of this pathogenic yeast species. This binding was manifested predominantly by the peptide moieties of the mannans forming hydrophobic bonds with the plastic molecule. Eliminating the peptide of each mannan by treating it with a hot aqueous alkaline solution of NaBH4 also eliminated color development in the EIA.

Adhesiveness↗
PubMed1986

Specific perfusion pattern in stress 201Tl myocardial scintigraphy of left main coronary artery disease.

The usefulness of stress 201Tl myocardial scintigraphy for identifying left main coronary artery disease was evaluated with data from 23 patients with 50% or more narrowing of the left main coronary artery and 56 patients with 75% or more narrowing of the major coronary arteries but without left main coronary artery involvement (no left main coronary artery disease). Quantitative evaluation of stress perfusion scintigrams in all five patients with narrowing of the left main coronary artery of 90% or more showed a characteristic perfusion pattern (left main pattern) of extensive homogeneous defect over the whole anterolateral segment and simultaneous defects in all radii of the high anteroseptal and high posterolateral segments. On the other hand, such a perfusion pattern was noted in only 1 of 18 patients with less than 90% stenosis of the left main coronary artery and in only 1 of 56 patients with no left main coronary artery disease.

Coronary Circulation↗
PubMed1986

Acetolysis of Pichia pastoris IFO 0948 strain mannan containing alpha-1,2 and beta-1,2 linkages using acetolysis medium of low sulfuric acid concentration.

To obtain manno-oligosaccharides containing beta-1,2-linked nonreducing terminal groups from the mannan of Pichia pastoris IFO 0948 strain by acetolysis, an attempt was made to establish the reaction conditions under which cleavage of the alpha-1,6 linkage took place preferentially leaving manno-oligosaccharides composed largely of beta-1,2 linkages. By the action of an ordinary acetolysis medium, a 10/10/1 (v/v) mixture of acetic anhydride, acetic acid, and sulfuric acid at 40 degrees C for 13 h or at 25 degrees C for 120 h, the O-acetyl derivative of this mannan gave mannose, mannobiose, mannotriose, and mannopentaose. However, treatment of the same O-acetyl mannan with a 50/50/1 (v/v) acetolysis medium at 40 degrees C for 15 h gave a mannotetraose in addition to mannose, mannobiose, mannotriose, and mannopentaose. Use of a 100/100/1 (v/v) acetolysis medium at 40 degrees C for 36 h gave a more satisfactory result, a mixture of oligosaccharides, from mannose to mannopentaose, which contained more mannotetraose than mannopentaose. Because both mannotetraose and mannopentaose contained alpha-1,2 and beta-1,2 linkages, it was concluded that an acetolysis medium containing a low concentration of sulfuric acid, up to 0.5% (v/v), facilitates the preferential cleavage of the alpha-1,6 linkage, leaving manno-oligosaccharides containing the beta-1,2 linkage which was found to be labile to the action of the 10/10/1 (v/v) acetolysis medium.

Acetylation↗
PubMed1986

Characterization of phosphomannan-protein complexes isolated from viable cells of yeast and mycelial forms of Candida albicans NIH B-792 strain by the action of Zymolyase-100T.

The isolation of phosphomannan-protein complexes from the viable cells of yeast (Y) and mycelial (M) forms of Candida albicans NIH B-792 strain was conducted by treatment with Zymolyase-100T followed by fractional precipitation with cetyltrimethylammonium bromide. The M-form complex was found to contain smaller amount of phosphate (1.3%) than that of the Y-form complex (1.6%). Proton magnetic resonance (PMR) spectra of these complexes indicated that the content of beta-1,2-linked oligomannosyl and nonreducing terminal alpha-1,3-linked mannopyranosyl residues in the M-form complex was lower than that of the Y-form complex. With hot 10 mM HCl, the Y-form complex released a mixture of oligosaccharides ranging from mannose to mannoheptaose, while the M-form complex produced lower oligosaccharides, from mannose to mannotetraose. Upon acetolysis, the acid-modified complex of the M form gave mainly mannotetraose, while that of the Y form produced mainly mannopentaose and mannohexaose in addition to mannotetraose. The average length of branching moieties of the mannan of Y-form cells was therefore longer than that of M-form cells. These results indicate that the Y to M transformation of this C. albicans strain accompanies the suppression of enzyme activity concerning the biosynthesis of mannan such as beta-1,2- and alpha-1,3-mannosyltransferases to synthesize the phosphomannan-protein complex containing mannan moiety with incomplete structure.

Candida albicans↗
PubMed1986

Altered glomerular localization of heparan sulfate proteoglycan in experimental nephritides.

The distribution of heparan sulfate proteoglycan (HS-PG) was examined electron microscopically by the high iron diamine (HID) method in puromycin aminonucleoside (PAN) nephrosis, accelerated Masugi nephritis (NTN), and serum sickness nephritis induced by bovine serum albumin (BSA nephritis) in the rat. In PAN nephrosis rats, no change was observed in the distribution of HS-PG in the lamina rara externa (LRE) of the glomerular basement membrane (GBM) throughout the experiment. In NTN rats, however, the loss of HS-PG was observed, and it was associated with subepithelial electron dense deposits formed possibly by serum sickness mechanism, but not with inflammatory cell infiltration. In BAS nephritis, immune deposits were seen in mesangial, subendothelial, intramembranous and subepithelial areas. The deposits in the former three areas seemed to have little reciprocity with the loss of HS-PG and proteinuria. Urinary protein increased in accordance with the development of subepithelial deposits and the loss of HS-PG in the area of the deposits in the LRE. These results indicate that HS-PG could be preserved even in marked proteinuric states in morphologically intact basement membrane, but altered and lost distribution of HS-PG associated with subepithelial immune deposits could in turn result in the development of proteinuria.

Animals↗
PubMed1986

Comparison of the defibrillation threshold and the upper limit of ventricular vulnerability.

To examine the relationship between the defibrillation threshold and the strength of shocks that induce ventricular fibrillation during the vulnerable period, we determined the defibrillation threshold in 22 open-chest dogs using epicardial defibrillation electrodes with the cathode at the ventricular apex and the anode at the right atrium. We also determined whether there was an upper limit of shock strength that induces fibrillation in the vulnerable period by giving shocks of various energy through these same electrodes during the repolarization phase of paced rhythm. The above determinations were also made with the anode at the ventricular apex and the cathode at the right atrium in eight of the dogs and with the cathode at the ventricular apex and the anode at the left atrium in another eight of the dogs. In all dogs for all electrode configurations, there was an upper limit to the shock strength that induced ventricular fibrillation during the vulnerable period. Depending on the electrode combination, this upper limit of ventricular vulnerability either was not significantly different from or was slightly lower than the defibrillation threshold. The correlation coefficient between the two was highly significant for all three electrode configurations. These results support the hypothesis that successful defibrillation with epicardial electrodes requires a shock strength that reaches or exceeds the upper limit of ventricular vulnerability and that shocks slightly lower than the defibrillation threshold fail because they reinitiate ventricular fibrillation by stimulating portions of the myocardium during their vulnerable period.

Animals↗
PubMed1986

Activation during ventricular defibrillation in open-chest dogs. Evidence of complete cessation and regeneration of ventricular fibrillation after unsuccessful shocks.

To test the hypothesis that a defibrillation shock is unsuccessful because it fails to annihilate activation fronts within a critical mass of myocardium, we recorded epicardial and transmural activation in 11 open-chest dogs during electrically induced ventricular fibrillation (VF). Shocks of 1-30 J were delivered through defibrillation electrodes on the left ventricular apex and right atrium. Simultaneous recordings were made from septal, intramural, and epicardial electrodes in various combinations. Immediately after all 104 unsuccessful and 116 successful defibrillation shocks, an isoelectric interval much longer than that observed during preshock VF occurred. During this time no epicardial, septal, or intramural activations were observed. This isoelectric window averaged 64 +/- 22 ms after unsuccessful defibrillation and 339 +/- 292 ms after successful defibrillation (P less than 0.02). After the isoelectric window of unsuccessful shocks, earliest activation was recorded from the base of the ventricles, which was the area farthest from the apical defibrillation electrode. Activation was synchronized for one or two cycles following unsuccessful shocks, after which VF regenerated. Thus, after both successful and unsuccessful defibrillation with epicardial shocks of greater than or equal to 1 J, an isoelectric window occurs during which no activation fronts are present; the postshock isoelectric window is shorter for unsuccessful than for successful defibrillation; unsuccessful shocks transiently synchronize activation before fibrillation regenerates; activation leading to the regeneration of VF after the isoelectric window for unsuccessful shocks originates in areas away from the defibrillation electrodes. The isoelectric window does not support the hypothesis that defibrillation fails solely because activation fronts are not halted within a critical mass of myocardium. Rather, unsuccessful epicardial shocks of greater than or equal to 1 J halt all activation fronts after which VF regenerates.

Animals↗
PubMed1986

Effect of administration route on the selective lymphatic delivery of cyclosporin A by lipid-surfactant mixed micelles.

The absorption and lymphatic delivery of a new immunosuppressive drug, cyclosporin A (CsA), with the aid of lipid surfactant mixed micelles (MM) system using different administration routes were studied in the thoracic duct cannulated rat model at a dose level of 7 mg/kg. The rectal or intraperitoneal (i.p.) administration of CsA indicated a small amount of CsA in the plasma and in the lymph for 6 h. As oral routes, intrastomach (i.s.) and intraduodenal (i.d.) administration of CsA were performed and high lymph CsA levels were obtained. The i.s. administration of CsA resulted in the highest CsA levels in the lymph, 16 micrograms/ml, about twenty times higher than the rectal or i.p. administration. These results strongly support the usefulness of an oral CsA dosage form for the selective lymphatic delivery of CsA in clinical immunosuppressive therapy by means of a new mixed micelles system.

Administration, Oral↗
PubMed1986

Degradation of myocardial structural proteins in myocardial infarcted dogs is reduced by Ep459, a cysteine proteinase inhibitor.

The purpose of this study is to clarify whether cysteine proteinases play an important role in the degradation of myocardial proteins in the infarcted tissue. We studied the effects of a cysteine proteinase inhibitor, Ep459, on degradation of cardiac structural proteins caused by ischemia due to coronary artery ligation for 24 h. Proteolytic effects of purified cysteine proteinases on isolated cardiac tissue were also examined. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, degradation of cardiac structural proteins, particularly of myosin heavy chain, alpha-actinin and troponin-I was observed in the infarcted tissue. Treatment with Ep459 significantly reduced protein degradation and total activity of cathepsins B and L in the infarcted tissue, compared with the findings in the untreated group. The electrophoretic pattern of the infarcted myocardium was similar to that of myofibrillar proteins degraded by cathepsins B and L. These results suggest that cysteine proteinases, particularly cathepsins B and L, are involved in degradation of myofibrillar proteins in myocardial infarction.

Animals↗