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Biomedical subjects

T Horie

Publications and source records attributed to T Horie.

At least 253 records · Page 14Linked to original sources
PubMed1996

[Relationship between exercise induced ischemia and left ventricular dysfunction; simultaneous assessment of perfusion and function images with 99mTc-tetrofosmin myocardial scintigraphy].

The purpose of this study was to evaluate the relationship between exercise induced ischemia and left ventricular dysfunction, ergometer exercise 99mTc-tetrofosmin myocardial scintigraphy was performed using one day protocol (exercise/rest). Subjects consisted of 68 patients without previous myocardial infarction; without coronary artery disease (CAD) (n = 36) and with CAD (n = 32). Perfusion and function images were evaluated simultaneously. Perfusion image was taken by single photon emission tomography (SPECT). Quantitative analysis was performed with normal data-base. The area of abnormal perfusion, less than normal lower limits, was named as extent score (ES). Left ventricular ejection fraction (LVEF) was measured by first-pass study. According to ES on stress image, 32 patients with CAD were divided into 3 groups; ES < 10% (n = 15), ES = 10-20% (n = 7) and ES > 20% (n = 10). LVEF at rest among 4 groups were not different. LVEF at peak exercise was 61.7+/ -5.3% in CAD (-), 59.0 +/- 5.8% in ES < 10%, 57.4 +/- 6.6% in ES = 10-20% and 47.4 +/- 10.5% in ES > 20%. LVEF in ES > 20% at peak exercise was lowest significantly. Thus, simultaneous perfusion and function images were evaluated for the relationship between exercise induced ischemia and left ventricular dysfunction. If extent score on stress image was more than 20% of left ventricle, significant left ventricular dysfunction was observed.

Aged↗
PubMed1996

Imipramine-induced inactivation of a cytochrome P450 2D enzyme in rat liver microsomes: in relation to covalent binding of its reactive intermediate.

Preincubation of microsomes from male Wistar rats with imipramine (IMI) in the presence of NADPH caused a time-dependent loss of bunitrolol 4-hydroxylase activity, indicating that the CYP2D enzyme is inactivated during IMI metabolism, which has also been observed after in vivo administration of IMI. A similar effect was obtained when desipramine, an N-demethylated metabolite of IMI, was used as an inhibitor, whereas 2-hydroxy-IMI had no effect on the activity. Thus, it seems likely that the inactivation of the CYP2D enzyme is related to 2-hydroxylation process of IMI. Incubation of microsomes with [3H]IMI in the presence of NADPH resulted in covalent binding of a 3H-labeled material to microsomal protein. Formation rates of the reactive metabolites covalently bound to protein followed Michaelis-Menten kinetics, and the K(m) value (1.1 microM) was close to that for microsomal IMI 2-hydroxylation. The metabolism-dependent covalent binding of [3H]IMI was lower in Dark Agouti rats, which is an animal model of CYP2D deficiency, than in Wistar rats. The binding was inhibited by propranolol and quinidine, a substrate and an inhibitor of CYP2D, respectively, and by an antibody against CYP2D. Similar strain difference (Dark Agouti < Wistar) and inhibitory effects by the compounds and the antibody were observed in IMI 2-hydroxylase but not in N-demethylase activity. SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) of microsomal protein incubated with [3H]IMI and NADPH showed that the binding was prominent at the molecular mass of approximately 50 kDa, which would be consistent with the P450 protein being a target for the binding. Furthermore, proteins to which [3H]IMI metabolites covalently bound were immunoprecipitated with the anti-CYP2D antibody. These results suggest that IMI is biotransformed into a chemically reactive metabolite (probably arene-oxide) through its 2-hydroxylation step by the CYP2D enzyme in rat liver microsomes, and the metabolite binds covalently to the enzyme itself, resulting in the inactivation.

Amino Acid Sequence↗
PubMed1996

Purification and characterization of rhesus monkey liver amido hydrolases and their roles in the metabolic polymorphism for E6123, a platelet-activating factor receptor antagonist.

We previously showed that a polymorphism for E6123 [(S)-(+)-6- (2-chlorophenyl)-3-cyclopropanecarbonyl-8,11-dimethyl-2,3,4,5- tetrahydro-8H-pyrido[4',3':4,5]thieno[3,2-f][1,2,4]triazolo[4,3-a] [1,4]diazepine] metabolism exists only in rhesus monkeys. In the present study, we purified, from rhesus monkey hepatic microsomes, three amido hydrolases that are involved in the metabolic polymorphism. Two forms of amido hydrolase from an extensive metabolizer and one from a poor metabolizer were purified by Q-Sepharose Fast Flow, Red A-agarose, octylamino-Sepharose 4B, and hydroxyapatite-Ultrogel chromatography, after solubilization with Lubrol. The three purified enzymes had the same molecular mass (47 kDa), and their amino-terminal amino acid sequences were identical. The enzymes were different from various known carboxylesterases in terms of substrate specificity, molecular mass, and amino-terminal amino acid sequence. They resembled arylacetamide deacetylase from human hepatic microsomes with respect to molecular mass and amino-terminal amino acid sequence. The KM values of the high and low affinity enzymes in the extensive metabolizer and the sole enzyme in the poor metabolizer were 37.6, 73.0, and 76.5 microM, respectively. The Vmax values were 3312.4, 504.8, and 427.9 pmol/min/mg of protein, respectively. The high affinity enzyme in extensive metabolizer appears to be quite distinct, whereas the low affinity enzyme in extensive metabolizer in similar or identical to the sole enzyme in poor metabolizer. Thus, the metabolic polymorphism in rhesus monkey may depend upon the existence of the high affinity enzyme in extensive metabolizer.

Amidohydrolases↗
PubMed1996

[Exercise-induced asthma].

Exercise-induced asthma (EIA) is common in children. In our experience, the incidence of EIA in adults with asthma was 54.4% (37 of 68), and those with and without EIA similar in many ways. Anti-cholinergic drugs were effective in patients with central airway obstruction during episodes of EIA, but disodium cromoglycate protected 80% of EIA patients regardless of the site of airway obstruction. The relationship between chemical mediators and EIA remains controversial but our data show a close relationship between the production of neutrophil chemotactic factor and the severity of EIA. To investigate the mechanism of EIA, we used hyperpnea-induced bronchoconstriction in sensitized rabbits. In this model, bronchoconstriction followed inhalation of dry air regardless of temperature; there was a refractory period, and the bronchoconstriction was completely blocked by an anti-cholinergic drug. The results of studies of inhalation of hypertonic saline, hyperosomolar solutions and amiloride suggest that hyperpnea-induced bronchoconstriction is caused by degranulation of mast cells or by vagal stimulation secondary to changes in osmolarity and in sodium concentration in the airway surface, which result from water loss induced by inhalation of dry air. Vascular phenomena are probably not involved in EIA.

Adult↗
PubMed1995

Quantitative EEG in never-treated schizophrenic patients.

To clarify whether patients with schizophrenia still show EEG slowing in the absence of psychopharmacological treatment, EEG was analyzed in 20 acute never-treated schizophrenics and 20 age-matched healthy controls using the computerized wave-form recognition method. Compared to controls, schizophrenics had more fast theta (6-8 Hz) and slow alpha (8-9 Hz) activity, and less fast alpha activity (9-13 Hz). The average EEG frequency at O1 correlated negatively with total and positive symptom scores on the BPRS in the schizophrenic group. These findings confirm that the frequency of alpha rhythm is slowed in schizophrenia and that this slowing is possibly related to the expression of psychopathology in this disorder.

Adult↗
PubMed1995

Oxidative stress in isolated rat hepatocytes during naproxen metabolism.

Naproxen, a non-steroidal anti-inflammatory drug, induced lipid peroxidation in isolated hepatocytes of rats. The viability of the hepatocytes decreased upon lipid peroxidation, and this effect was accompanied by the formation of high molecular weight protein aggregates in the hepatocytes. Protein aggregation occurred slowly compared with the formation of thiobarbituric acid reactive substances (TBARS). The increase of TBARS was strongly correlated with the decrease of intracellular glutathione. Chemiluminescence was produced from the hepatocyte suspension during naproxen metabolism, and was correlated with the formation of TBARS. These results indicate that lipid peroxidation in the hepatocytes was provoked by reactive oxygens produced in the process of naproxen metabolism.

Animals↗
PubMed1995

Mechanisms of biliary excretion of lithocholate-3-sulfate in Eisai hyperbilirubinemic rats (EHBR).

Biliary excretion of lithocholate-3-sulfate is markedly impaired in EHBR. To examine the mechanism of biliary lithocholate-3-sulfate excretion in EHBR, the effects of colchicine treatment, a vesicular transport inhibitor, and infusion of taurocholate and organic anions were studied in EHBR and Sprague-Dawley rats. Colchicine treatment and taurocholate infusion had no effect of biliary lithocholate-3-sulfate excretion in EHBR, suggesting that biliary lithocholate-3-sulfate excretion is not mediated by the vesicular transport or by the bile acid excretory pathway. In control Sprague-Dawley rats, both sulfobromophthalein and dibromosulfophthalein infusion inhibited biliary lithocholate-3-sulfate excretion. In contrast, in EHBR dibromosulfophthalein infusion inhibited biliary lithocholate-3-sulfate excretion but BSP infusion did not. Indocyanine green and pravastatin infusion did not affect biliary lithocholate-3-sulfate excretion but pravastatin infusion had no effect in EHBR. These findings indicate that, whether physiologically important or not, two of more excretory pathways for organic anions exist at the canalicular membrane other than the ATP-dependent one.

Animals↗
PubMed1995

Relationship between responsiveness to colony stimulating factors (CSFs) and surface phenotype of leukemic blasts.

We examined the responsiveness of leukemic cells to colony stimulating factors (CSFs) as determined by 3H-TdR incorporation and surface phenotypes of leukemic blasts. In acute myeloid leukemia (AML), CD13 and/or CD33 positive and HLA-DR negative M1 and M3 cases tended to show high response to G-CSF, GM-CSFs and IL-3, however, all HLA-DR positive M1, M2, M4 and M5 cases were unresponsive to CSFs but showed high autonomous growth. In acute lymphocytic leukemia (ALL), no response was observed to any CSFs but high autonomous growth was found in mixed leukemia cases. Sole T or B lineage cases showed low autonomous growth. These results suggest the varied nature of the proliferative state in leukemia and the existence of a subgroup in M1.

Cell Division↗
PubMed1995

Kinetic analysis of hepatobiliary transport for conjugated metabolites in the perfused liver of mutant rats (EHBR) with hereditary conjugated hyperbilirubinemia.

PURPOSE: Previously, we found that the biliary excretion of the 6-hydroxy-5,7-dimethyl-2-methylamino-4-(3-pyridylmethyl) benzothiazole (E3040) glucuronide is severely impaired in Eisai hyperbilirubinemic rats (EHBR), while that of sulfate remains normal (Takenaka et al., J. Pharmacol. Exp. Ther., 274: 1362-1369, 1995). The purpose of the present study is to clarify the mechanisms for impairment of the biliary excretion of E3040 glucuronide in EHBR. METHODS: We kinetically analyzed the disposition of the conjugates in the perfused liver at steady state. The uptake of the conjugates into the isolated canalicular membrane vesicles (CMVs) was also examined. RESULTS: At steady state, the bile/liver unbound concentration ratios of the conjugates were 40-400 in both rat strains, indicating a highly concentrated process. The biliary excretion clearance (CLu,bile) of the glucuronide, defined for the unbound concentration in the liver, was decreased in EHBR to 1/30 of that in normal rats, whereas the CLu,bile of the sulfate was comparable between the two rat strains. In vitro, the transport of E3040 glucuronide into CMV prepared from SD rats exhibited the ATP dependency, whereas minimal effect of ATP was observed on the uptake of the glucuronide into CMV from EHBR. In contrast, the uptake of E3040 sulfate was comparable between SD rats and EHBR. Furthermore, ATP did not stimulate the uptake of sulfate into the CMVs. CONCLUSIONS: It was suggested (1) that the excretion of E3040 glucuronide across the bile canalicular membrane is mediated by the primary active transporter which is defective in EHBR and (2) that the bile canalicular transport system for E3040 sulfate is different from that for the glucuronide in that the former remains normal in EHBR.

Adenosine Triphosphate↗
PubMed1995

TNF-alpha regulates IL-4-induced Fc epsilon RII/CD23 gene expression and soluble Fc epsilon RII release by human monocytes.

We examined the regulatory effects of TNF-alpha on IL-4-induced gene expression of the low-affinity receptor for IgE (Fc epsilon RII/CD23) in human monocytes and IL-4-induced soluble Fc epsilon RII (sFc epsilon RII) release from monocytes. IL-4-induced Fc epsilon RII expression on the surface of monocytes was reduced by TNF-alpha as early as 1 day after culture and the effect of TNF-alpha increased with prolonged culture. The present analysis was designed to examine whether or not TNF-alpha could suppress IL-4-induced Fc epsilon RII mRNA expression and enhanced IL-4-induced sFc epsilon RII release. The addition of TNF-alpha to monocyte cultures with IL-4 significantly reduced Fc epsilon RII expression on the surface of monocytes and significantly increased sFc epsilon RII release from monocytes. Over time, there was an inverse relationship between the disappearance of cell surface Fc epsilon RII and the appearance of sFc epsilon RII in culture supernatants. Fc epsilon RII mRNA expression in monocytes cultured with IL-4 was not affected by TNF-alpha when examined at 6 h after cultivation. When the cells were cultured with TNF-alpha for more than 24 h, however, TNF-alpha down-regulated IL-4-induced Fc epsilon RII mRNA levels. This correlated with the kinetics of down-regulation of IL-4-induced Fc epsilon RII expression on the surface of monocytes by TNF-alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1995

Oxidative metabolism of bunitrolol by complementary DNA-expressed human cytochrome P450 isozymes in a human hepatoma cell line (Hep G2) using recombinant vaccinia virus.

We examined the oxidative metabolism of a beta-blocker bunitrolol (BTL) by 10 human cytochromes P450 (CYP) (1A2, 2A6, 2B6, 2C8, 2C9, 2D6, 2E1, 3A3, 3A4 or 3A5), which were individually expressed in Hep G2 cells with a vaccinia virus complementary DNA expression system. Among the 10 isozymes, only CYP2D6 and 1A2 at a substrate concentration of 5 microns, and CYP2C8 and 2C9 in addition to the two isozymes at a BTL concentration of 1 mM, exhibited detectable BTL 4-hydroxylase activities. The activities at 1 mM BTL were on the order of CYP2D6 (100% as relative activity) > CYP1A2 (86%) >> CYP2C8 and 2C9 (7-8%). Enzyme kinetic parameters of CYP2D6 were calculated to be 4.41 microns as a Km value and 0.442 nmol min-1 per nmol CYP as a Vmax value. Kinetic parameters of CYP1A2 were calculated as 295 microns and 0.411 nmol min-1 per nmol CYP for Km and Vm values, respectively. These results suggest that both CYP2D6 and 1A2 primarily catalyse BTL 4-hydroxylation, but that the former is a predominant isozyme responsible for the reaction at a low substrate concentration range of BTL in human liver.

Adrenergic beta-Antagonists↗
PubMed1995

Elevation of serum soluble vascular cell adhesion molecule-1 (sVCAM-1) levels in bronchial asthma.

We have previously shown the elevation of serum soluble intercellular adhesion molecule-1 (sICAM-1) and soluble E-selectin (sE-selectin) in patients with bronchial asthma during asthma attacks. In the present study, we extended our earlier study by measuring serum sVCAM-1 levels by ELISA in 45 patients with bronchial asthma (23 atopic and 22 non-atopic) during asthma attacks and in stable conditions in order to assess further the state of adhesion molecules in allergic inflammation of bronchial asthma. The levels of sVCAM-1 in sera obtained during bronchial asthma attacks were higher than those in sera obtained in stable conditions. These findings were observed regardless of atopic status. To examine the regulatory mechanism in the elevation of serum sVCAM-1 levels, serum tumor necrosis factor-alpha (TNF-alpha) levels were measured by ELISA. TNF-alpha levels in sera obtained during bronchial asthma attacks were higher than those in sera obtained in stable conditions. The nature of change in serum TNF-alpha levels correlated with the nature of change in serum sVCAM-1 levels, but serum TNF-alpha levels did not correlate with serum sVCAM-1 levels. These results suggest that higher levels of sVCAM-1 during asthma attacks may reflect the up-regulation of VCAM-1 expression in allergic inflammation, and that a soluble form of VCAM-1 molecules may be useful markers for the presence of allergic inflammation. TNF-alpha is shown to enhance the expression and release of VCAM-1 in vitro, however; the regulatory mechanism in the elevation of serum sVCAM-1 levels remains to be clarified.

Adult↗
PubMed1995

Interaction of the cell-binding domain of fibronectin with VLA-5 integrin induces monokine production in cultured human monocytes.

The effect of fibronectin on IL-1 alpha, IL-1 beta, tumour necrosis factor-alpha (TNF-alpha), and IL-6 production was investigated with cultured monocytes isolated from human peripheral blood. Monokine concentrations were determined by both ELISA and bioassay. Fibronectin markedly stimulated the secretion of IL-1 alpha, IL-1 beta, TNF-alpha and IL-6 from cultured monocytes in a dose-dependent manner, with the maximal effect apparent within 24 h. Northern blot analysis revealed a marked increase in the abundance of mRNA specific for each monokine on exposure of monocytes to fibronectin. Monoclonal antibodies to the alpha chain of very late antigen (VLA)-5, the beta 1 integrin, the alpha chain of Mac-1, and the beta 2 integrin, as well as the synthetic peptide of GRGDSP (which corresponds to the cell-binding domain of fibronectin), inhibited (> 50%) fibronectin-induced monokine production. Monoclonal antibodies to the alpha chain of VLA-4, and the alpha chain of LFA-1, as well as the synthetic peptide CS-1 (which corresponds to the alternatively spliced connecting segment of fibronectin) and the control peptide GRADSP, had no inhibitory effect on monokine production. A MoAb, R60, that recognizes an epitope of the fibronectin molecule that includes the RGD sequence, inhibited monokine production, whereas the MoAb Y16, which recognizes another epitope of fibronectin not including RGD, did not. These results indicate that fibronectin-induced production of IL-1 alpha, IL-1 beta, TNF-alpha and IL-6 from cultured monocytes is mediated predominantly by interaction of the cell-binding domain of fibronectin with VLA-5, although Mac-1 also may contribute to this effect of fibronectin. Our results indicate that the interaction of fibronectin with integrins may contribute to the cytokine network in inflammatory response.

Binding Sites↗