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Biomedical subjects

K Chiba

Publications and source records attributed to K Chiba.

At least 289 records · Page 16Linked to original sources
PubMed1991

Occurrence of cholesterol 7 alpha- and 7 beta-hydroperoxides in rat skin as aging markers.

Evidence for presence of cholesterol 7 alpha- and 7 beta-hydroperoxides in rat skin was presented for the first time. The 7-hydroperoxides in rat skin were reduced with sodium borohydride and trimethylsilylated for identification with the authentic compounds by gas chromatography/mass spectrometry. A content of cholesterol 7-hydroperoxides in rat skin, determined by high performance liquid chromatography with a chemiluminescence detector, highly correlated with the age of rats (r = 0.874; between 1 and 45 weeks old), indicating that cholesterol 7 alpha- and 7 beta-hydroperoxides were good markers for aging.

Aging↗
PubMed1991

Biochemical characterization and tissue distribution of hamster complement C1s.

Several mAb (PG11, NG7, and ED4) against hamster complement C1s were obtained. PG11 and NG7 were shown to cross-react with human and rat C1s. By using an immunohistochemical method, we examined localization of C1s in tissues of hamsters and rats. Present results revealed a widespread yet specific staining of hamster C1s which is associated with endoderm-, mesoderm-, and neuroectoderm-derived cells. For example, chondrocyte of hyaline cartilage and surface epithelium of the stomach were strongly positive. Intestinal epithelium, muscle cells, pia mater and epithelium of the choroid plexus of the ventricle, and hepatocytes were also stained. The synthesis of hamster C1s in these organs was confirmed by RNA blot hybridization. Secretion of C1s into the culture medium was revealed by immunoblot analysis in cell lines of hepatocytes, kidney cells, and myoblasts of rat or hamster.

Animals↗
PubMed1991

Effect of NCO-700, an inhibitor of protease, on lysosomal rupture in the ischemic myocardium.

The effect of NCO-700 (1), a protease inhibitor, on subcellular distribution of lysosomal enzymes was studied in the ischemic perfused rat heart. Ischemia was induced by lowering the afterload pressure of the working heart preparation. The subcellular distribution of lysosomal enzymes was estimated by the ratio of the activities of cathepsin D, beta,N-acetylglucosaminidase, and acid phosphatase in the cytoplasm to the total enzyme activities. Ischemia caused subcellular redistribution of lysosomal enzymes from the lysosomes to the cytoplasm, indicating the rupture of lysosomes. Compound 1 (1.75 x 10(-4) M) was provided for the heart 5 min before the onset of ischemia. Compound 1 appeared to inhibit the rupture of lysosomes being caused by ischemia. The mechanism by which 1 protects the myocardium against ischemic injury may involve the inhibition of lysosomal rupture in the ischemic myocardium.

Acetylglucosaminidase↗
PubMed1991

Antiinflammatory properties of E5090, a novel orally active inhibitor of IL-1 generation.

E5090 is a novel orally active inhibitor of IL-1 generation without cyclooxygenase-inhibiting activity. The effects of E5090 on several inflammatory animal models were investigated in rats. In adjuvant arthritis, E5090 suppressed both the paw swelling and the enhancements of ESR and number of peripheral blood leucocytes, like the steroidal antiinflammatory drug prednisolone. However, the thymus was not withered by E5090 though it was by prednisolone. In type II collagen-induced arthritis, E5090 inhibited paw swelling and joint destruction. E5090 was effective in acute inflammatory models such as carrageenin-induced paw edema, and adjuvant-induced local hyperthermia, and also showed analgesic effects against inflammatory pain and antipyretic effects. The results suggest that this orally active inhibitor of IL-1 generation, E5090, may be a therapeutically useful antiinflammatory drug with a novel mechanism of action.

Acrylates↗
PubMed1991

A novel inhibitor of IL-1 generation, E5090: in vitro inhibitory effects on the generation of IL-1 by human monocytes.

E5090 is an orally active inhibitor of IL-1 generation, being converted in vivo into the pharmacologically active deacetylated form (DA-E5090). In vitro effects of DA-E5090 on the generation of IL-1 by human monocytes stimulated with LPS were examined. DA-E5090 inhibited both IL-1 alpha and IL-1 beta generation by human monocytes stimulated with 1 microgram/ml of LPS in a dose dependent-manner (1-10 microM), as determined by LAF assay and ELISA. Northern blotting analysis indicated that DA-E5090 inhibits transcription of IL-1 alpha and IL-1 beta m-RNAs.

Acrylates↗
PubMed1991

A novel inhibitor of IL-1 generation, E5090: in vivo inhibitory effect on the generation of IL-1-like factor and on granuloma formation in an air-pouch model.

The in vivo production of IL-1-like activity was investigated in the exudate of a rat air-pouch inflammatory model. An inflammatory reaction was induced by LPS injection into the air-pouch. IL-1 activity in the exudate reached the maximum level at 4 h and then rapidly decreased until 8 h after the injection of LPS. Orally administered E5090 and prednisolone dose-dependently inhibited the generation of IL-1 activity. Both compounds also suppressed chronic granuloma formation in parallel with the IL-1 inhibition. On the other hand, indomethacin had no effect on either IL-1 generation or granuloma formation in spite of the complete inhibition of PGE2 generation. These results suggest that E5090 inhibits the production of IL-1-like activity in the exudate and exhibits steroid-like antiinflammatory effects.

Acrylates↗
PubMed1991

Cerebral perfusion patterns in vascular dementia of Binswanger type compared with senile dementia of Alzheimer type: a SPECT study.

Cerebral perfusion patterns in 18 cases with vascular dementia of Binswanger type (VDBT) (8 moderate and 10 severe cases) were compared with 25 cases with senile dementia of Alzheimer type (SDAT) (16 moderate and 9 severe cases) and 14 controls by single photon emission computed tomography using N-isopropyl-p-123I iodoamphetamine (IMP) as a tracer. The cerebral: cerebellar IMP uptake ratio (%) (CCR) was used as a measured of relative cerebral perfusion. The CCRs were about 85-90% in all areas in controls. Moderate VDBT patients showed a remarkable decrease of CCRs in the basal grey region (thalamus and basal ganglia) (right 79%, left 77%) and in the frontal area (right 79%, left 80%) (P less than 0.01). In severe VDBT patients a significant decrease of the CCR was noted in all regions (P less than 0.01). The decrease of mean CCRs in the hemispheres was significantly correlated with the severity of disease determined by psychometric testing. Patients with SDAT showed a significant decrease of the CCR in the parietal (right 71%, left 74%) and right temporal (78%) areas in the moderate stage (P less than 0.01), and further progression of dementia was associated with low perfusion areas extending to the the frontal areas (78%, P less than 0.01). These differences in the perfusion patterns and their changes with progression of the illnesses may be reflected in characteristic clinical features.

Aged↗
PubMed1991

Collagenase production in the exudate of a novel adjuvant-induced air pouch inflammation model in rats.

To elucidate the role of collagenase in tissue destruction in chronic inflammation (e.g., in rheumatoid arthritis), we established a novel air pouch model in rats. Ten ml of air was injected subcutaneously on the dorsa of F344 rats, and 24 hours thereafter, Freund's complete adjuvant was injected into the air pouch. A remarkably high activity of trypsin-activated collagenase was detected dose-dependently in the pouch fluid at 8 days after the challenge injection. Concomitantly with the increase of collagenase activity, the weight of granuloma formed in the pouch decreased, suggesting that collagenase participates in the resorption of granuloma tissues.

Air↗
PubMed1991

Inhibition by cyclo-oxygenase inhibitors of interleukin-6 production by human peripheral blood mononuclear cells.

The effects of cyclo-oxygenase inhibitors on interleukin-6 (IL-6) production by human peripheral blood mononuclear cells were examined. Indomethacin and Y-9223, a novel cyclo-oxygenase inhibitor, inhibited the increases in the IL-6 level in the culture medium of both mitogen-stimulated adherent cells and non-adherent cells fractionated from mononuclear cells. Northern blotting showed that the mitogen-induced increase in the expression of IL-6 mRNA was inhibited by indomethacin and Y-9223, indicating that these agents inhibit IL-6 biosynthesis. Aspirin, ibuprofen, and phenylbutazone also inhibited IL-6 production by adherent cells stimulated with lipopolysaccharide (LPS). There was, however, no direct relationship between inhibition of IL-6 and prostaglandin E2 (PGE2) production by these agents. The addition of PGE2 corresponding to the amount produced by adherent cells stimulated with LPS slightly increased IL-6 production by unstimulated adherent cells, but to a lower level than that reached with LPS. An anti-PGE2 antibody partially blocked IL-6 production by adherent cells stimulated with LPS. These results suggest that, in addition to the inhibition of PGE2 production, other mediators including cyclooxygenase products or other action mechanisms are involved in the inhibition of IL-6 production by these drugs.

Benzopyrans↗
PubMed1991

Dose-dependent kinetics of orally administered 6-mercaptopurine in children with leukemia.

To determine whether the pharmacokinetics of 6-mercaptopurine (6-MP) would show dose dependency, we studied three different single oral doses in eight children (aged 3.6 to 15.1 years) with acute leukemia in remission. Marked interindividual differences in maximum plasma concentration (Cmax) and the area under the plasma concentration-time curve (AUC) were observed when children received the 50 mg/m2 dose. This variability decreased when the doses were increased. Six of the eight children showed a disproportionate increase in the AUC with increasing doses; the other two had a proportionate relationship between the AUC and dose. Overall mean (+/- SD) Cmax and AUC values increased disproportionately (88 +/- 123, to 326 +/- 194, to 653 +/- 344 ng/ml for Cmax, and 147 +/- 180, to 451 +/- 177, to 1291 +/- 415 ng/ml per hour for AUC, respectively) when the dose increased from 50 to 87.5 mg/m2 and then to 175 mg/m2. The results suggest that a saturable first-pass metabolism of oral 6-MP occurs with increasing oral doses in some, but not all, children. Whether and to what extent this pharmacokinetic character of oral 6-MP affects the interindividual difference in systemic exposure to the drug in children with leukemia receiving maintenance therapy require further studies.

Administration, Oral↗
PubMed1991

Corneal epithelium in diabetic patients.

The corneal epithelia of phakic control (n = 13), aphakic control (n = 10), diabetic phakic (n = 10), and diabetic aphakic patients (n = 13) were surveyed under a wide-field specular microscope with a special contact lens. In control patients, the corneal epithelium showed relatively hexagonal cells, which we divided into three groups: bright cells, medium-bright cells, and dark cells. These epithelial cells displayed a smooth-surface configuration. In diabetic phakic patients, the epithelium seemed almost normal, with slightly more irregularity. In diabetic aphakic patients, the epithelium appeared larger. The cells were irregular and easy to distinguish from normal cells. Morphometric analysis showed that the mean cell areas of phakic control, aphakic control, diabetic phakic, and diabetic aphakic patients were 648 +/- 152, 643 +/- 125, 658 +/- 146, and 821 +/- 203 microns 2, respectively. The increase in the average cell area in diabetic aphakic patients was statistically significant. Although no apparent changes of the epithelium could be detected in the diabetic corneal epithelium under biomicroscopy, abnormalities that could be evaluated by specular microscopic images and morphometric analysis were observed.

Aphakia↗
PubMed1991

Metoprolol oxidation polymorphism in a Korean population: comparison with native Japanese and Chinese populations.

We examined metoprolol oxidation capacity in 218 unrelated, healthy Korean subjects using the 8 h urinary metabolic ratio (MR) of metoprolol to alpha-hydroxymetoprolol after an oral dose of 100 mg metoprolol tartrate. The results were compared with those from 295 Japanese and 107 mainland Chinese whose metoprolol oxidation capacities were assessed in a similar manner. The frequency of occurrence of poor metabolisers (PMs) was 0.5% (1/218) in the Korean, 0.7% (2/295) in the Japanese and 0% in the Chinese population. However, the respective mean (+/- s.d.) MRs (0.84 +/- 1.14 and 0.87 +/- 0.90) in the Korean and Japanese extensive metabolisers (EMs) were significantly (P less than 0.001) less than that in the Chinese EMs (2.81 +/- 2.35), and the mode of the distribution histogram and the probit plot of data for Chinese EMs were shifted to the right compared with those for Korean and Japanese EMs. The results indicate that Koreans, like Japanese and mainland Chinese, have a much lower frequency of the PM phenotype of debrisoquine/sparteine-type oxidation compared with that reported for Caucasian populations. Chinese EMs appear to have a lower capacity to metabolise metoprolol to alpha-hydroxymetoprolol compared with Korean or Japanese EMs.

Adolescent↗
PubMed1991

Twenty-four-hour variation of blood pressure in vascular dementia of the Binswanger type.

Using a noninvasive portable blood pressure recorder, we compared 24-hour variations of blood pressure among 1) 35 patients with Binswanger-type dementia, 2) 43 with lacunar-type dementia, 3) 26 with a single lacunar stroke, and 4) 30 controls. Each group was divided into antihypertensive-treated and -untreated subgroups. Among the untreated subgroups, patients with Binswanger-type dementia had significantly greater 24-hour mean systolic blood pressures, 24-hour systolic blood pressure standard deviations, and maximal systolic blood pressure variations than the controls (p less than 0.05). Among the treated patients, blood pressure variability increased similarly in all subgroups with cerebrovascular lesions compared with the controls (p less than 0.05). The nocturnal blood pressure decreases seen in the controls were absent among both untreated and treated patients with Binswanger- or lacunar-type dementia (p less than 0.05). Our results suggest the importance of hypertension, short-term variations in blood pressure, and a sustained nighttime elevation of blood pressure for the pathogenesis of both Binswanger-type and lacunar-type dementia in patients receiving antihypertensive medication.

Aged↗
PubMed1991

Synthesis of [carbonyl-14C]sparfloxacin.

A new antimicrobial quinolone, sparfloxacin (5-amino-1-cyclopropyl-7- (cis-3,5-dimethyl-1-piperazinyl)-6,8-difluoro-1,4-dihydro-4-oxoquinoline -3- carboxylic acid, AT-4140; CAS 110871-86-8), was labeled by 14C for studies of disposition and metabolism. Ethyl pentafluoro[carbonyl-14C]benzoylacetate (I) was reacted with ethyl orthoformate, cyclopropylamine and then potassium tert-butoxide to give a quinolone intermediate (IV). A benzylamino derivative (V) obtained by condensation of IV and benzylamine was subject to catalytic hydrogenolysis and hydrolyzed to give the carboxyl derivative (VII), which was condensed with cis-2,6-dimethylpiperazine to form [carbonyl-14C]sparfloxacin. The average yield of 3 preparations was 41.5% and specific activities were 310.8-366.3 MBq (8.4-9.9 mCi)/mmol. Both chemical and radiochemical purities were greater than 99%.

Chromatography, Thin Layer↗
PubMed1991

[A case of follicular bronchiolitis with broncho-pleural fistula in rheumatoid arthritis].

A 67-year-old male diagnosed clinically as having rheumatoid pleuritis and bronchiolitis was treated with adrenocorticosteroid. His clinical findings improved, but following the tapering of the steroid dose, exacerbation occurred. After the steroid dose was increased, serological findings improved, but chest X-ray findings revealed no improvement. To re-evaluate the etiology of the bronchiolar lesion, open lung biopsy was performed. The biopsy specimen showed lymphocytic infiltration and formation of lymphoid follicles in and around the bronchioles. The pulmonary lesion was diagnosed as follicular bronchiolitis.

Aged↗
PubMed1991

Stereoselective disposition and metabolism of disopyramide in pediatric patients.

Pharmacokinetics of disopyramide (DP) enantiomers was studied in six pediatric patients, 5 to 12 years old, with arrhythmias after i.v. and p.o. administrations of racemic DP. The enantiomers of DP and its active metabolite, mono-N-dealkyldisopyramide, in plasma and urine were determined using a chiral, high-performance liquid chromatography. Plasma protein binding of DP was measured by ultrafiltration. Because the protein binding of DP was not only concentration-dependent but also stereoselective (i.e., S-DP binds to protein more extensively than R-DP), unbound pharmacokinetic parameters were used for evaluating the kinetic behaviors of DP enantiomers. The pediatric age patients had the mean (+/- S.D.) systemic clearance of 15.0 +/- 3.8 and 12.7 +/- 3.9 ml/min/kg for unbound S- and R-DP, respectively, which were not only stereoselectively different (P less than .05) but also at least about twice greater than the reported normal adult values. The mean postinfusion elimination half-life values for unbound S- and R-DP (2.7 +/- 0.5 and 2.8 +/- 0.4 hr, respectively) in pediatric patients were shorter than those reported from normal adults (approximately equal to 4 to 5 hr). The mean nonrenal (i.e., hepatic) clearance for unbound S- and R-DP (11.1 +/- 4.1 and 8.1 +/- 3.9 ml/min/kg, respectively) were also stereoselectively different (P less than .01) and accounted for approximately equal to 70% of the unbound systemic clearance of the respective enantiomers.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗