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Biomedical subjects

M Ogata

Publications and source records attributed to M Ogata.

At least 199 records · Page 11Linked to original sources
PubMed1993

Characterization and redox properties of high molecular mass cytochrome c3 (Hmc) isolated from Desulfovibrio vulgaris Miyazaki.

Two kinds of high molecular mass cytochrome c3 (Hmc) were isolated from Desulfovibrio vulgaris Miyazaki, one from the membrane (mHmc), the other from the soluble fraction (sHmc). Molecular masses of both Hmcs determined by SDS-PAGE are 65 kDa. Each Hmc molecule is composed of a single polypeptide chain and contains 16 hemes. sHmc and mHmc have identical UV-visible absorption spectra of a typical c-type cytochrome (three peaks at 530, 419, and 355 nm in the ferri form, and four peaks at 553, 523, 419, and 325 nm in the ferro form), and similar amino acid composition. There is no peak at 695 nm in the ferri form, but a Soret peak (423 nm) with a shoulder at 432 nm, indicative of the presence of a high-spin heme, appeared at low reduction stage. Hmcs are fragile proteins and readily denatured by bubbling with gas or by stirring. From the redox titration of sHmc monitored spectroscopically in the presence of standard redox dyes, the midpoint potentials of 16 hemes (E1 approximately E16) were determined. These hemes are classified into four groups based on their Eis: positive (E1 = 60, E2 = 15 mV), slightly negative (E3 = E4 = E5 = E6 = E7 = -120, E8 = -125, E9 = -135 mV), negative (E10 = E11 = -190, E12 = E13 = -195, E14 = -205 mV), and very negative (E15 = E16 = -260 mV) groups (may be deviated from the true microscopic values due to heme-heme interactions). The role of Hmc in the energy metabolism of this bacterium is discussed.

Amino Acids↗
PubMed1993

Dextran sulphate enhancement of lipopolysaccharide-induced tumour necrosis factor-alpha production by murine peritoneal macrophages: correlation with macrophage blockade.

Proteose peptone-induced murine peritoneal macrophages (M phi) were preincubated with 100-800 micrograms/ml of dextran sulphate (DS) 500 (M(r) 500,000) or DS1000 (M(r) 1,000,000). After 2-24 h of the preincubation, the M phi were stimulated with 1 microgram/ml of lipopolysaccharide (LPS) in vitro for 18 h in DS-free culture medium. The culture supernatants were then collected for TNF assay. The LPS-induced TNF activity of M phi supernatant preincubated with DS500 or DS1000 for 6 h was enhanced by up to about ten-fold compared with those preincubated without DS. This enhancing effect was not observed when M phi were preincubated with 100-800 micrograms/ml of low molecular weight DS5 (M(r) 5,000) or neutral dextran (Dex) 500 (M(r) 500,000). The enhancement of LPS-induced TNF-alpha production from M phi was observed after 2 or 4 h of incubation with DS1000 or DS500, respectively. The phagocytic activity of M phi was determined in vitro by the ingestion index and phagocytic capacity using Saccharomyces cerevisiae. Treatment with DS500 or DS1000 significantly suppressed the phagocytic activity from 2 h after the incubation, but this suppression was not observed in M phi incubated with DS5 or Dex500. Our experiments indicate that DS500 and DS1000 act directly on M phi and enhance LPS-induced TNF-alpha production from M phi, and that the enhancement is closely related to the suppression of M phi phagocytic function.

Animals↗
PubMed1993

An antagonist of platelet-activating factor suppresses endotoxin-induced tumor necrosis factor and mortality in mice pretreated with carrageenan.

We found that carrageenan (CAR), that is, sulfated polygalactose, can enhance both lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) production and the rate of lethality in mice (M. Ogata, S. Yoshida, M. Kamochi, A. Shigematsu, and Y. Mizuguchi, Infect. Immun. 59:679-683, 1991). It has been reported that platelet-activating factor (PAF) antagonists reduce the rate of mortality from endotoxin shock. However, there are few reports regarding the effect of PAF antagonists on TNF production. The aim of the present study is to examine the effect of TCV-309, a new PAF antagonist, on LPS-induced TNF production and mortality in mice pretreated with CAR. ddY mice (6 to 7 weeks old) were injected intraperitoneally with CAR (5 mg per mouse) and were then divided into two groups: mice treated with a PAF antagonist (TCV-309; Takeda Pharmaceutical Co.) and control mice. The mice treated with PAF antagonist received indicated doses of TCV-309 subcutaneously (s.c.) at 30 min before LPS injection, while the control mice received 1 ml of saline s.c. at the same time. All mice were stimulated by intravenous injection of LPS (50 micrograms per mouse) at 24 h after pretreatment with CAR. At intervals after injection of LPS, serum samples were obtained for a TNF assay in which cytotoxicity to L929 cells was measured. TCV-309 both significantly suppressed LPS-induced TNF production and reduced mortality in a dose-dependent manner. When TCV-309 was administered at 30 min before injection of LPS, the effect of TCV-309 on the suppression of TNF activity was at its peak. Treatment with TCV-309 (990 micrograms per mouse) s.c. significantly improved the survival rate after challenge with LPS compared with the survival rate of control mice. Although the 50% lethal dose of LPS was 15 micrograms per mouse for control mice, it increased to 102 micrograms per mouse for mice that were treated s.c. with TCV-309 (990 micrograms per mouse). Even in vitro, TCV-309 also inhibited LPS-induced TNF production in thioglycolate-elicited macrophages. It was concluded that PAF plays an important role in endotoxin-induced TNF production and mortality.

Animals↗
PubMed1993

Increased expression of PDGF A- and B-chain genes in rat lungs with hypoxic pulmonary hypertension.

To study the molecular basis of vascular remodeling in pulmonary hypertension, we developed an experimental system in which male Sprague-Dawley rats were exposed to hypoxia for up to 3 wk. Both the right ventricular systolic pressure and gravimetric index for right ventricular hypertrophy were higher in rats exposed to hypoxia for 3 wk than those of age-matched control rats (P < 0.01), indicating that pulmonary hypertension was established under conditions used. To examine the possible involvement of platelet-derived growth factor (PDGF) in the pulmonary vascular remodeling caused by hypoxia, we cloned rat PDGF A- and B-chain cDNA and prepared specific cRNA probes. Northern blot analysis revealed that PDGF B-chain mRNA levels in the lungs were increased, reached a maximum of day 1, and were sustained at day 3, whereas PDGF A-chain mRNA levels reached a maximum on day 3. Thus the increase in the PDGF B-chain mRNA level precedes that in the PDGF A-chain mRNA level. These results suggest that the PDGF A- and B-chain products may be coordinately and sequentially involved in hypoxic pulmonary vascular remodeling.

Amino Acid Sequence↗
PubMed1993

Effects of a combination therapy of anticoagulant and vasodilator on the long-term prognosis of primary pulmonary hypertension.

A therapy consisting of a combination of an anticoagulant and a vasodilator was investigated to determine its effects on the long-term prognosis of primary pulmonary hypertension (PPH). Twenty patients with PPH who had undergone diagnostic catheterization in our hospital were studied. The mean follow-up period after the initial catheterization was 6 years, with the longest follow-up being 24.4 years. Seven patients were treated with warfarin as an anticoagulant, combined with either isoproterenol (3 patients) or nifedipine (4 patients) as a vasodilator (AV group). The remaining 13 patients were not treated (control group). Although there were no significant differences in the physical activity or hemodynamics between the groups, improvement was seen in 43% of the AV group and in only 7.6% of the controls. The 5 year survival rate was significantly higher in the AV group (57% vs 15%; P < 0.05). Hemodynamics were evaluated repeatedly in 8 patients and improvement was seen only in the AV group. These results suggest that a therapy consisting of a combination of an anticoagulant and a vasodilator may improve the long-term prognosis of PPH.

Adolescent↗
PubMed1993

Congenital nephrogenic diabetes insipidus in an adult.

A 35-year-old man with congenital nephrogenic diabetes insipidus (NDI) is reported. Renal biopsy revealed miniaturized and rounded mitochondria of the proximal tubular cells and decreased brush-borders. Trichlormethiazide combined with triamterene resulted in an apparent reduction of daily urine volume and concomitant increment in urine osmolarity. The present case seems rare in that some morphological changes in the renal tissues could be demonstrated in an adult case with congenital NDI.

Adult↗
PubMed1993

Vestibular neuronitis evaluated by the combined galvanic test.

Forty-two patients with unilateral vestibular neuronitis were examined by the combined galvanic test (CGT), consisting of the galvanic eye movement test (GEMT) and the galvanic body sway test (GBST). Results of the CGT were evaluated with respect to the time period from the onset of vestibular neuronitis. A favorable recovery was observed earlier with the GBST than the GEMT. We believe that this discrepancy may be due to the difference in compensation between the vestibulo-ocular reflex and the vestibulo-spinal reflex.

Adult↗
PubMed1993

Interpretation of the combined galvanic test. Findings from cases with vestibular neuronitis.

The combined galvanic test (CGT) was developed in our department for simultaneous recording of galvanic eye movement test (GEMT) and galvanic body sway test (GBST). Twelve cases of vestibular neuronitis were studied first with the caloric test, and then with the CGT. The findings of the caloric test corresponded to those of the GEMT, but did not always correspond to those of the GBST. Thus we suggest that the GBST reflects an abnormality in a system different from that reflected by the caloric test and GEMT. It is likely that the caloric response mainly originates from the semicircular canal system. Thus the GEMT may reflect an abnormality in the semicircular canal system, while the GBST reflects an abnormality in the otolithic system. The CGT may thus be a feasible method of differentiating the disorders of the semicircular canal system from those of the otolithic system in the vestibular nervous system.

Adult↗
PubMed1993

The properties and mec A gene of the methicillin-resistant Staphylococcus aureus isolated in Fukushima Medical College Hospital.

The 106 methicillin-resistant strains of Staphylococcus aureus (MRSA) isolated in Fukushima Medical College Hospital were examined for their properties and mecA gene. The strains produced four types of coagulase, of which type II was the most common, produced by 84 (79.2%). Beta-lactamase was produced by 58 (50%). Enterotoxins were produced by 45 (42.5%), most of which (39/106, 36.8%) were of type A. Thirty-four strains (32.1%) produced both enterotoxins and toxic shock syndrome toxin-1. All strains were susceptible to vancomycin and arbekacin, although they were mostly resistant to many other antibiotics. Using the polymerase chain reaction (PCR) technique, the mecA gene was detected in 57 (91.9%) of the 62 strains used. In addition, one of the 42 methicillin-susceptible strains isolated had the mecA gene. These results indicate that detection of the mecA gene by the PCR technique is a rapid and accurate way to identify methicillin resistance.

Bacterial Proteins↗
PubMed1993

Inhibitory effect of alpha-tocopherol on methemoglobin formation by nitric oxide in normal and acatalasemic mouse hemolysates.

The inhibitory effect of alpha-tocopherol on methemoglobin formation in normal and acatalasemic mice was studied by exposing their hemolysates to nitric oxide. Methemoglobin formation in normal and acatalasemic mouse hemolysates exposed to nitric oxide were significantly inhibited by the addition of alpha-tocopherol at final concentrations ranging from 1.2 to 5.8 mM. Negative correlations were observed between the logarithm of alpha-tocopherol concentration and the methemoglobin formation. The formation of methemoglobin in acatalasemic mouse hemolysates was greater than that in normal mouse hemolysates with or without added alpha-tocopherol. The methemoglobin formation in acatalasemic mice was also significantly inhibited by addition of more than 500 units/ml of catalase, and the methemoglobin formation in normal and acatalasemic mice was also inhibited with sodium diethyldithiocarbamate at a final concentration of 1 M.

Acatalasia↗
PubMed1993

Thymic stroma-derived T-cell inhibitory factor (TSTIF) 1. TSTIF induces inhibition of antigen-stimulated T-cell proliferation.

The present study investigates the capacity of the MRL104.8a thymic stromal cell clone to modulate T-cell growth. The culture supernatant (SN) from the MRL104.8a stromal cell monolayer was added to cultures of Th-clones with or without T-cell receptor (TCR) stimulation as provided by antigen (Ag) plus splenic antigen-presenting cells (APC). The results demonstrated that the MRL104.8a SN containing IL-7 activity induced dose-dependent proliferation of Th cells when they were not stimulated with Ag/APC. In contrast, addition of the same SN to cultures of Th cells during stimulation with Ag/APC resulted in potent dose-dependent inhibition of their proliferation. IL-7 contained in the SN was neither responsible for, nor involved in the inhibition event, because the inhibition was not observed with rIL-7 and was not neutralized by anti-IL-7 antibody. The growth inhibition of the Th clone in the presence of Ag plus APC was also induced by IL-10 or TGF-beta. However, the MRL104.8a SN-induced growth inhibition was mediated by a factor distinct from these cytokines, because (1) IL-10 cDNA was not amplified in polymerase chain reaction (PCR) products derived from MRL104.8a cells; (2) TGF-beta cDNA was detected in the PCR products, but only marginal levels of TGF-beta activity in an active form were found in the MRL104.8a SN and the SN-induced inhibition was not prevented by anti-TGF-beta antibody; and (3) addition of rIL-7 to antigen-stimulated cultures containing rTGF-beta or rIL-10 induced IL-7 mediated Th proliferation, whereas the MRL104.8a SN-induced inhibition was still observed in the presence of excess rIL-7. Moreover, this factor, designated thymic stroma-derived T-cell inhibitory factor, was found to have a m.w. of 20-25 x 10(3) and to exhibit heparin-binding property. Thus, these results indicate that the MRL104.8a thymic stromal cell clone produces a potentially novel factor that induces inhibition of antigen-stimulated T-cell proliferation.

Animals↗
PubMed1993

[Plasma amino acid levels in alcoholics].

Plasma aromatic amino acid (AAA) and branched-chain amino acid (BCAA) concentrations were determined in 197 alcoholics. The BCAA/AAA molar ratio in patients with alcohol withdrawal symptoms was compared with the ratio in patients without such symptoms. The BCAA/AAA molar ratio in patients with emotional disturbance or with transient hallucination was significantly lower than that in patients without these symptoms. The BCAA/AAA molar ratio tended to be lower in patients with alcohol withdrawal convulsion or with delirium tremens as compared to patients without such symptoms. The BCAA/AAA molar ratio had a negative correlation with plasma total bilirubin and LDH and had a positive correlation with plasma choline esterase and albumin. Oral administration of amino acid preparations (Aminoleban EN) to the patients elevated the BCAA/AAA molar ratio and normalized liver function. These results indicate that abnormalities of amino acid metabolism caused by liver damage in alcohol dependence may have an important role in the pathogenesis of alcohol withdrawal syndrome.

Adult↗
PubMed1993

The effects of glucose on plasma amino acids and pyruvate during upper abdominal surgery.

To assess the potential benefits of perioperative glucose administration, the plasma concentrations of insulin, free fatty acids, ketone bodies, amino acids, lactate, and pyruvate were measured in 20 patients undergoing partial gastrectomy. Ten patients received intravenous glucose at 10 g/h during the operation, and the other 10 patients, as control, received no glucose. Plasma glucose, insulin activity, pyruvate and alanine concentrations in the glucose-receiving group increased significantly during the operation in comparison with the control group. In contrast, in the glucose-receiving group the plasma ketone bodies and branched-chain amino acids, especially leucine and isoleucine, decreased significantly during surgery. These results suggest that administration of glucose stimulated insulin secretion and resulted in accumulation of the substrates such as pyruvate and alanine which were utilized readily in the body. Glucose administration is useful in suppressing catabolism during upper abdominal surgery.

Amino Acids↗
PubMed1993

Investigation of high salt intake in a Nepalese population with low blood pressure.

The relation between BP and the factors influencing an increase in BP with age were investigated in the inhabitants of two representative hilly (Kotyang: 206 men and 212 women) and suburban (Bhadrakali: 265 and 244) villages in Nepal. BP for both sexes was statistically significantly higher in Bhadrakali than in Kotyang. Neither hypertension nor elevation of BP with age for men and very few women (1.4%) with hypertension were observed in Kotyang, while 10.9% of men and 4.9% of women were found to be hypertensive in Bhadrakali. Average urinary Na excretion was 183-221 mEq/day in both villages. Urinary Na/K ratio, percentage body fat (%Fat), total protein, total cholesterol and serum Ca were statistically significantly higher in Bhadrakali than in Kotyang, and maximal oxygen uptake and serum Mg were higher in Kotyang. In spite of high salt consumption, there was no increase in BP with age in Kotyang's males, suggesting that the BP may be influenced by physical activity, fat-free mass and nutrient consumption in addition to the high sodium intake, and that extremely high physical activity and very low %Fat could serve to mute the influence of high sodium intake.

Adult↗
PubMed1992

Cell-mediated cleavage of Pseudomonas exotoxin between Arg279 and Gly280 generates the enzymatically active fragment which translocates to the cytosol.

Pseudomonas exotoxin (PE) is a three-domain toxin which is cleaved by a cellular protease within cells and then reduced to generate two prominent fragments (Ogata, M., Chaudhary, V. K., Pastan, I., and FitzGerald, D. J. (1990) J. Biol. Chem. 265, 20678-20685). The N-terminal fragment is 28 kDa in size and contains the binding domain. The 37-kDa C-terminal fragment, which translocates to the cytosol, contains the translocation domain and the ADP-ribosylation domain. Cleavage followed by reduction is essential for toxicity since mutant forms of the toxin that cannot be cleaved by cells are nontoxic. Previous results with these mutants suggest that cleavage occurred in an arginine-rich (arginine residues are at positions 274, 276, and 279) disulfide loop near the beginning of the translocation domain, but the exact site of cleavage was not determined. Since very few molecules of the 37-kDa fragment are generated within cells it was not possible to determine the site of cleavage by performing a conventional N-terminal sequence analysis of the 37-kDa fragment. Two experimental approaches were used to overcome this limitation. First, existing amino acids near the cleavage sites were replaced with methionine residues; this was followed by the addition of [35S]methionine-labeled versions of these toxins to cells. The pattern of radioactive toxin fragments recovered from the cells indicated that the toxin was cleaved either just before or just after Arg279. Second, [3H]leucine-labeled toxin was produced and added to the cells. Sequential Edman degradations were performed on the small amount of radioactive 37-kDa fragment that could be recovered from toxin-treated cells. A peak of radioactivity in the fifth fraction indicated that leucine was the 5th amino acid on the C-terminal side of the cleavage site. This result confirmed that cleavage was between Arg279 and Gly280.

ADP Ribose Transferases↗
PubMed1992

Instability of assembled T-cell receptor complex that is associated with rapid degradation of zeta chains in immature CD4+CD8+ thymocytes.

The intracellular fate of newly synthesized T-cell receptor (TCR) chains was compared in CD4+CD8+ (double positive; DP) thymocytes and in CD4+CD8- or CD4-CD8+ (single positive; SP) thymocytes. Purified DP and SP thymocytes from normal adult mice were analyzed by pulse-chase metabolic labeling and immunoprecipitation with specific anti-TCR antibodies. Biosynthesis of invariant chains (CD3 gamma, -delta, -epsilon, and zeta) was comparable between DP and SP thymocytes, whereas DP thymocytes synthesized TCR alpha and TCR beta chains at lower and higher levels than SP thymocytes, respectively. These newly synthesized TCR chains were degraded at different rates in SP thymocytes based on their sensitivities for degradation as previously reported: TCR alpha, TCR beta, CD3 gamma, and CD3 delta chains were rapidly degraded and CD3 epsilon and zeta chains were stable. Although the degradation rates of clonotypic and invariant CD3 chains were similar in DP and SP thymocytes, the zeta subunit was rapidly degraded in DP thymocytes (t1/2, approximately 1.5 hr). Degradation of zeta was inhibited by NH4Cl, implicating lysosomes as the site of degradation. Comparison of TCR subunit assembly in DP and SP thymocytes demonstrated that, despite the same relative rate of formation of TCR complexes in a pulse period (30 min), complete complexes were unstable and degraded during the subsequent 6 hr of chase in DP thymocytes. This contrasted with the stability and a progressive increase in the levels of completely assembled complexes in SP thymocytes. Thus, these results demonstrate that a unique posttranslational regulation operates in the formation of TCR complexes in DP thymocytes and that lack of stability of complete TCR complexes is a crucial mechanism that may account for the limited surface TCR expression on this thymocyte subset.

Ammonium Chloride↗