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Biomedical subjects

Y Matsuki

Publications and source records attributed to Y Matsuki.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Effects of ascorbic acid on the metabolic fate and the free radical formation of iproniazid].

The effects of ascorbic acid (AA) on the metabolic fate of iproniazid (IPN) and on the free radical intermediates derived from IPN were investigated in rats. After oral administration of IPN with or without AA, the plasma concentration and the urinary excretion of IPN and its metabolites were determined by gas chromatography-mass spectrometry using stable isotope labeled compounds as internal standards. In the excretion of IPN and its metabolites except hydrazine (Hy), the differences between co-administration and single administration were not observed. The excretion of Hy, which is a known hepatotoxic metabolite, decreased clearly in the co-administration of IPN and AA. When IPN and AA were co-administered orally, the profiles of plasma levels of IPN and its metabolites were almost similar after the administration of IPN alone. Furthermore, no differences between i.v. co-administration and i.v. administration alone were observed. These results indicated that AA did not affect both absorption and metabolism of IPN. By the electron spin resonance (ESR) spectroscopy and spin-trapping technique, the ESR signals due to the alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (4-POBN) adducts induced by isopropylhydrazine (IP-Hy) were two-fold higher than those by IPN in microsomal systems. The free radical formations of IPN and IP-Hy were significantly inhibited by AA in a dose dependent manner. The 4-POBN-trapped radical species generated from IPN and IP-Hy were presumed to be an isopropyl radical by the results of mass spectrometry.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Fluorescent probe-labeled lipid microsphere uptake by human endothelial cells: a flow cytometric study.

Lipid microspheres have been used as carriers of drugs such as prostaglandin E1 (lipo-PGE1) and corticosteroid (liposteroid). Lipo-PGE1 is used for the treatment of chronic arterial occlusive diseases because its activity is far greater than that of free PGE1 in vivo. To verify the fact that the drug carriers, lipid microspheres, are preferentially taken up by endothelial cells, we labeled lipid microspheres with a fluorescent probe, DiI (DiI-LM), and observed them in some in vitro models. Stoichiometric fluorescence was obtainable, and the fluorescence was stable between pH 3.3 and pH 8.9. Human umbilical vein endothelial cells and cells of a human endothelial cell line, ECV304, showed increased uptake of DiI-LM, 81% and 61%, respectively. In contrast, uptakes were less than 7% in human skin fibroblasts, 3T3 cells, and human neutrophils. Prominent perinuclear fluorescence was also observed in endothelial cells by fluorescence microscopy. DiI-LM and flow cytometric analysis will be useful for studies to elucidate the precise mechanism of the selective accumulation of lipid microspheres by cells in blood vessel walls.

Carbocyanines↗
PubMed1992

[A case of antiphospholipid syndrome associated with left subclavian artery thrombosis and left external iliac vein thrombosis].

Arterial thrombosis is one of the major symptoms of antiphospholipid syndrome (APS). However, thrombosis in a primary branch of the aorta has rarely been reported in APS. We report here a case of APS complicated by thromboses in both the left subclavian artery and the left external iliac vein. A 32-year-old woman was admitted in May, 1990 complaining of no pulse in the left superficial arteries (e.g., left radial artery) for the past 5 years and acute swelling of the left lower extremity. A left ascending phlebography showed an occlusion of the external iliac vein and arteriography revealed obstruction in the left subclavian artery. Collateral circulations were developed at the site of each thrombus. Clotting and immunological studies revealed a prolonged APTT, a high titer of anticardiolipin antibody and lupus anticoagulant positive. We ruled out various diseases and clinical risk factors predisposing to both arterial and venous thromboses. Accordingly, we concluded that both thromboses were based on APS. Following treatment with anticoagulants, aspirin and corticosteroid, the swelling of her left thigh was diminished and the antibody titer was decreased within 3 months.

Adult↗
PubMed1992

Detection of inflammatory cytokine messenger RNA (mRNA)-expressing cells in human inflamed gingiva by combined in situ hybridization and immunohistochemistry.

Cells expressing messenger RNA (mRNA) for inflammatory cytokines [interleukin-1 (IL-1), tumour necrosis factor-alpha (TNF-alpha), IL-6, IL-8] were demonstrated by in situ hybridization in human inflamed gingiva. When this technique was used in conjunction with immunohistochemistry, IL-1 alpha and/or beta and IL-8 messages were observed predominantly on macrophages infiltrating the gingiva. TNF-alpha messages were abundant on macrophages and T cells. In contrast, the IL-6 mRNA were more widely distributed on many types of cells such as macrophages, T cells, fibroblasts, endothelial cells and B cells. This study clearly identified the cells which express mRNA for inflammatory cytokines in inflamed gingiva and suggested an involvement of cytokine network in the generation of human periodontitis.

Adult↗
PubMed1991

Continuous removal of anti-DNA antibody, using a new extracorporeal immunoadsorption system, in patients with systemic lupus erythematosus.

We performed selective and continuous immunoadsorption of anti-DNA antibodies from the blood of 6 patients with systemic lupus erythematosus, using a newly developed extracorporeal immunoadsorption system equipped with twin dextran sulfate-cellulose columns with an automated regenerating unit. Levels of anti-DNA, which were initially high, were rapidly diminished after 2-4 apheresis procedures in each patient; in 3 patients with proteinuria and 4 patients with lymphocytopenia, these symptoms also improved. Analysis of the kinetics and the adsorbed amounts of anti-DNA during the apheresis indicates that both the intravascular and the extravascular pool of anti-DNA are reduced with this potent apheresis technique.

Adult↗
PubMed1991

Effects of glucose and ascorbic acid on absorption and first pass metabolism of isoniazid in rats.

We examined the effect of glucose (Glu) and ascorbic acid (AA) on absorption and metabolism of isoniazid (INAH). After p.o. administration of INAH with or without Glu or AA, plasma concentration and urinary excretion of INAH and its metabolites, acetyl INAH (AcINAH), acetyl hydrazine (AcHy) and hydrazine (Hy), were determined by means of gas chromatography-mass spectrometry using stable isotope labeled compounds as internal standard. The combined administration of INAH with Glu or AA led to a significant decrease in the excretion of INAH and Hy, and a significant increase in the excretion of AcINAH and AcHy. The absorption amount of INAH was reduced to about one-half by the addition of Glu and the absorption rate of INAH markedly decreased in the case of co-administration of AA. Comparing the oral case with the results of i.v. administration, Glu and AA only affect the absorption process containing the first pass metabolism of INAH.

Animals↗
PubMed1991

[Effects of ascorbic acid on the free radical formations of isoniazid and its metabolites].

By the use of electron spin resonance (ESR) spectroscopy and of spin-trapping technique, the effects of ascorbic acid on the formation of the free radical intermediates due to isoniazid (INAH) and its metabolites were investigated with a microsomal system. When alpha-(4-pyridyl 1-oxide)-N-tert butylnitrone (4-POBN) was used as a spin trapping agent, the ESR signal due to hydrazine (Hy) was formed to be most intensive among others. Therefore, it was presumed that Hy is a potent intermediate to cause an INAH-induced hepatic injury. In the presence of ascorbic acid (AA), the free radical formation of Hy, INAH and acetyl hydrazine was significantly inhibited, suggesting that AA may affect the INAH-hepatitis. By the addition of inhibitors of cytochrome P-450 like metyrapone and CO, the generation of the radical from Hy decreased, confirming that the radical is formed by the cytochrome P-450 dependent microsome systems. The 4-POBN-trapped radical species generated from Hy was presumed to be the hydrazyl radical by the results of mass spectrometry.

Animals↗
PubMed1991

[Isotopic fractionation of iproniazid and isopropylhydrazine from their deuterated analogues and application for isotope dilution analysis by capillary gas chromatography].

Quantitative analyses of iproniazid (IPN) and deuterated analogue (IPN-d6) and of isopropylhydrazine (IP-Hy) and deuterated analogue (IP-Hy-d6) after conversion to pyrazole derivatives (IDP) were carried out by gas chromatography. The complete separation of protio- from deutero-forms of IPN and IDP was achieved by using a fused-silica CBP1 capillary column (50 m). The resolution coefficients between two isotopic molecules were 1.10 for IPN and 1.62 for IDP, respectively. The present isotopic fractionation procedure was applied to the isotope dilution analyses of IPN and IP-Hy. By the measurement of the samples prepared by the addition of known amounts of IPN and IPN-d6 to the control plasma and urine of rat, a linear relationship between peak height ratio and added amount ratio was observed. The correlation coefficients obtained by regression analysis were 0.9990 for the plasma and 0.9999 for the urine, respectively. In the case of IP-Hy, a linear relationship was also observed, and the correlation coefficients were 0.9998 for the plasma and 0.9997 for the urine, respectively. The present method was compared with the gas chromatography-mass spectrometry method in urinary samples from rats treated with IPN. The results of these parallel determinations were comparable.

Animals↗
PubMed1991

Pharmacokinetics of nizatidine in dogs and rats.

1. Plasma levels of nizatidine and two metabolites (N-desmethyl nizatidine and nizatidine S-oxide) were studied in dogs and rats. 2. The time-courses of plasma concentration of nizatidine after i.v. and oral administration to dogs well fitted a two-compartment model. Absorption after oral administration was rapid, and the peak plasma level (Cmax) and area under the plasma concentration-time curve (AUC) were proportional to doses. Absolute bioavailability was close to 100%, indicating that nizatidine has a negligible first-pass effect. 3. Nizatidine was eliminated by apparent first-order kinetics after i.v. administration to rats, and the elimination in rats was faster than in dogs. Bioavailability in rats was 72.4%, indicating a slight first-pass effect in rats. 4. When plasma clearance (Clp), or volume of distribution (Vd.beta), of nizatidine were plotted against animal body weight on a log-log scale, good correlations were obtained for rats, dogs and humans. 5. Peak levels (Cmax) of two metabolites were reached at 0.5-1.0 h after oral and i.v. administration of nizatidine to dogs. The elimination curves of the two metabolites were similar to that of nizatidine. Significant relationships were found between doses of nizatidine and Cmax or AUC of both metabolites.

Administration, Oral↗
PubMed1991

Interleukin-1 mRNA-expressing macrophages in human chronically inflamed gingival tissues.

Interleukin-1 (IL-1)-producing cells in inflamed gingival tissues obtained from patients with periodontitis were examined by combined immunohistochemistry and in situ hybridization. Macrophages, T cells, B cells, and endothelial cells were visualized in the lesions by the immunoperoxidase method using specific antibodies to each cell type. Subsequent in situ hybridization using 35S-labeled synthetic oligonucleotide probes complementary to human IL-1 alpha and IL-1 beta mRNA showed IL-1 transcripts in macrophages predominantly but not in T cells or B cells. Neither fibroblasts nor keratinocytes contained the IL-1 message to any significant extent. Endothelial cells also were essentially negative for IL-1 messages. These findings indicate that IL-1 is produced principally by macrophages in inflamed gingival tissues of humans.

Adult↗
PubMed1990

Regioselective N-acetylation as a route of nitro-9-phenylenediamine metabolism by rat liver cytosol.

Regioselectivity in N-acetylation of nitro-0-phenylenediamine, a widely used hair dye component, by rat liver cytosolic N-acetyltransferases was studied in relation to its substituent effects on enzymatic N-acetylation of mono-substituted anilines. Nitro-p-phenylenediamine was acetylated specifically at the N4-position to afford the N4-monoacetate, a major urinary metabolite in the rat, when incubated with rat liver cytosol fortified with acetyl-coenzyme A. N1-Acetylation of nitro-p-phenylenediamine did not take place even when the N4-monoacetate was used as a substrate, suggesting a strong steric hindrance effect of the ortho nitro group on the enzymatic N1-acetylation. The steric hindrance effect of the nitro group on the cytosolic N-acetylation of the ortho amino group was revealed by a comparative study carried out by using aniline, three respective regioisomers of nitroanilines and phenylenediamines as model substrates. The comparative study also indicated the enzymatic N-acetylation of the mono-substituted anilines to be strongly influenced by the electronic effect of the substituents. Regioselective N-acetylation in the hepatic cytosol was also investigated with N1- and N4-monoacetates of 1,2,4-triaminobenzene. The monoacetates yielded the N1,N4-diacetate, another major urinary metabolite of the hair dye component, in the rat, without concomitant formation of the N2,N4-diacetate or the N1,N2,N4-triacetate. The triacetate was formed only from the N1,N2-diacetate in the enzymatic reactions. A comparative study, carried out by using N-mono-acetates of three regioisomeric phenylenediamines, indicated that the N-acetyl group had a potent steric hindrance effect on the primary amino group at the ortho position.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylation↗
PubMed1987

Determination of isofloxythepin in biological fluids by gas chromatography-mass spectrometry.

A method for the determination of isofloxythepin in biological fluids by gas chromatography-mass spectrometry is described. Isofloxythepin was readily converted into the trimethylsilyl ether by treatment with N,O-bis(trimethylsilyl)trifluoroacetamide. This derivative was separated on a 5% OV-101 column and determined, employing newly prepared isofloxythepin-d7 as an internal standard. Clean-up of isofloxythepin in blood and urine was efficiently achieved by back-extraction with hexane or hexane-toluene (9:1) under acidic and basic conditions, while isofloxythepin glucuronide in biological fluids was isolated by ion-exchange chromatography on Dowex 50W-X4 resin. The detection limit of isofloxythepin by this method was 50 pg. The blood and urine levels of isofloxythepin after oral administration of the drug to dogs were monitored by the proposed method.

Animals↗
PubMed1987

Sensitive method for determination of captopril in biological fluids by gas chromatography-mass spectrometry.

A sensitive method for the determination of captopril in blood and urine by gas chromatography-mass spectrometry is described. In order to prevent oxidative degradation of captopril, its sulph-hydryl group was immediately protected by treatment with N-ethylmaleimide (NEM), and the resulting NEM adduct was then converted into the bis(pentafluorobenzyl) derivative. Derivatized captopril was separated on a 2% OV-1 column, exhibiting a single peak of the correct theoretical shape. The detection limit was estimated to be 100 pg by using S-benzylcaptopril as an internal standard. The blood level and urinary excretion of unchanged captopril orally administered to dogs were determined by the proposed method. In addition, epimerization of the proline moiety and formation of the sulphoxide or sulphone through the esterification step are also described.

Captopril↗