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Biomedical subjects

K Saitoh

Publications and source records attributed to K Saitoh.

At least 235 records · Page 13Linked to original sources
PubMed1993

Antithrombotic effect of recombinant human soluble thrombomodulin on endotoxin-induced disseminated intravascular coagulation in rats.

Thrombomodulin (TM) is an endothelial cell membrane glycoprotein which neutralizes thrombin procoagulant activity and accelerates the thrombin-catalyzed activation of protein C. We expressed recombinant human soluble TM (rhs-TM) in Chinese hamster ovary cells and compared the effects of rhs-TM and heparin on endotoxin-induced experimental disseminated intravascular coagulation (DIC) in rats. Experimental DIC was induced by a continuous intravenous infusion of endotoxin for four hours. rhs-TM or heparin was infused simultaneously with endotoxin. Treatment with rhs-TM significantly reversed the endotoxin-induced changes in significantly reversed the endotoxin-induced changes in following parameters: platelet count, fibrinogen level and fibrinogen and fibrin degradation products. Furthermore, glomerular fibrin deposits elevated by endotoxin treatment were reduced by the rhs-TM administration. Heparin showed the similar effects to rhs-TM. Activated partial thromboplastin time (APTT) in rats receiving rhs-TM were slightly longer than APTT in endotoxin-treated rats, but rats receiving heparin had much more prolonged APTT. From these results, we concluded that rhs-TM may be useful for the clinical treatment of DIC while having only minor adverse effects on APTT.

Animals↗
PubMed1993

Cloning and expression of large isoform of glutamic acid decarboxylase from human pancreatic islet.

Glutamic acid decarboxylase (GAD) catalyzes formation of gamma-aminobutyric acid from glutamic acid and is a major autoantigen in insulin-dependent diabetes mellitus. Its two isoforms, GAD65 and GAD67, are encoded by two separate genes. We prepared human islet cDNA library and screened it with cDNA probes of rat brain GAD67. We cloned the cDNA for GAD67, the large isoform of glutamic acid decarboxylase, and determined its nucleotide sequence. Sequencing of the resulting clone identified a 1,785 residue open-reading frame encoded a 594 amino acid polypeptide that showed a 99.4% similarity with GAD67 from human brain. The bacterially expressed human islet GAD67 protein was enzymatically active and immunoreactive. The isolation of cDNA for this additional islet GAD isoforms will be important in studying the etiology and pathogenesis of IDDM.

Amino Acid Sequence↗
PubMed1993

Case report: intestinal infarction after an aneurysmal occlusion of superior mesenteric artery in a patient with Behçet's disease.

A patient with Behçet's disease, accompanied by a large aneurysm of superior mesenteric artery, developed an ischemic enteritis with multiple perforated ulcers. The ischemic necrosis of the intestine preceded by recurrent abdominal pain was due to an aneurysmal occlusion of superior mesenteric artery, but not entero-Behçet's disease. This is the first case report of intestinal infarction that occurred in a patient with vasculo-Behçet's disease involving the superior mesenteric artery. Vasculo-Behçet's disease should be included in a differential diagnosis of acute mesenteric artery thrombosis.

Adult↗
PubMed1993

Pharmacokinetics and biochemical efficacy after single and multiple oral administration of losartan, an orally active nonpeptide angiotensin II receptor antagonist, in humans.

1. The pharmacokinetics and biochemical efficacy of losartan, an orally active nonpeptide angiotensin II (AII) receptor antagonist, were evaluated in healthy male volunteers after single and multiple oral administration. 2. Plasma and urinary concentrations of losartan and its active metabolite, E-3174, were determined by a specific high performance liquid chromatographic (h.p.l.c.) method. 3. Plasma concentrations of losartan were proportional to dose over the range of 25 to 200 mg and the terminal half-lives (t1/2,z) ranged from 1.5 to 2.5 h. The mean values of Cmax and AUC0-infinity increased in a dose-dependent manner. 4. Plasma concentrations of E-3174 were higher than those of losartan at all dose levels. The values of Cmax and AUC0-infinity for E-3174 were approximately 2 and 5-8 times higher than those for losartan, respectively. Also the value of t1/2,z was 2 times longer than that of losartan. 5. After multiple dosing for 7 days, the pharmacokinetics of losartan and E-3174 each did not change significantly between day 1 and day 7. 6. Plasma renin activity (PRA) and plasma concentrations of AII increased markedly at all dose levels. Plasma aldosterone levels were slightly reduced, but a similar decrease was also observed with placebo. 7. No clinically significant adverse reaction was observed in any of the volunteers during either study. Blood counts, routine laboratory tests, urine analyses, and electrocardiograms were also not modified by losartan. 8. Losartan appears to be a potent orally active angiotensin II antagonist with a relatively long duration of action.

Administration, Oral↗
PubMed1993

Cell proliferation kinetics of the bile duct epithelium of the rat.

Cell proliferation kinetics of the extrahepatic bile duct were studied by flash and cumulative labelling methods and immunohistochemical techniques. We compared the cell kinetics of the epithelium of the intra- and extra-pancreatic bile ducts and of the bile duct of the ampulla in rats administered intraperitoneally with bromodeoxyuridine (BrdUrd). After a single injection of BrdUrd (flash labelling), labelled cells appeared in the lower portion of the downgrowths of the epithelium in the intra- and extra-pancreatic bile ducts. A gradual accumulation of the labelled cells at the surface epithelium was observed during the cumulative labelling. After cumulative labelling the labelled cells gradually decreased in number and were finally confined to the degenerative cell zone of the surface epithelium 30 days later. Similarly, after a single injection of BrdUrd, the labelled cells in the bile duct of the ampulla appeared at the lower half of the crypt from where they migrated to the upper portion during cumulative labelling. These findings indicate that epithelial cells of the bile duct are renewed at the lower portion of the downgrowths of the epithelium, or crypt, and shed from the surface epithelium or upper portion of the fold. The labelling indices reached 23.83 +/- 7.47% in the intra-pancreatic bile duct, 14.74 +/- 7.99% in the extra-pancreatic bile duct and 43.42 +/- 4.40% in the bile duct of the ampulla at the end of 70 h cumulative labelling. The fluctuating values of the labelling index were higher in the bile duct of the ampulla than in the intra- or extra-pancreatic bile ducts. These results indicate that the bile-duct epithelium undergoes a slower renewal rate than the other parts of the gastrointestinal tract, and that the renewal time of the epithelial cells is shorter at the bile duct of the ampulla than at the intra- or extra-pancreatic bile ducts.

Animals↗
PubMed1993

Homologous desensitization of serotonin 5-HT2 receptor-stimulated intracellular calcium mobilization in C6BU-1 glioma cells via a mechanism involving a calmodulin pathway.

Serotonin 5-HT2 receptor-mediated intracellular Ca2+ mobilization was investigated in rat glioma C6BU-1 cells. The receptors became desensitized after previous exposure to 5-HT in a time- and concentration-dependent manner. The desensitization of 5-HT2 receptor-mediated intracellular signaling appeared to be homologous because previous exposure to 5-HT did not alter the response to other transmitters such as thrombin or isoproterenol and because previous exposure to thrombin or isoproterenol did not diminish the response to 5-HT. The desensitization induced by pretreatment with 5-HT was potently prevented by the naphthalenesulfonamide derivative W-7, a calmodulin antagonist, when it was cosupplied with 5-HT. Furthermore, the preventive effect of W-7 was greater than that of W-5, a weak analogue of W-7, and than that of H-7, a nonselective inhibitor of protein kinases. These results suggest that 5-HT2 receptor-mediated Ca2+ mobilization can be desensitized homologously after prolonged exposure to 5-HT in a calmodulin-dependent manner in rat glioma C6BU-1 cells.

Animals↗
PubMed1993

Diagnosis of childhood BK virus cystitis by electron microscopy and PCR.

A case of BK virus cystitis in a 5 year old boy is reported. This patient, who was not immunocompromised, had had acute cystitis for two weeks. Many intracytoplasmic inclusions were observed in urinary sediment smears stained by the Papanicolaou method. Electron microscopic examination showed virus particles, presumed to be human polyomavirus, in the nuclei of the degenerated urothelial cells. A DNA sequence of the BK virus was detected in 200-300 urothelial cells in Papanicolaou stained smears by the polymerase chain reaction. BK virus is an unusual cause of symptomatic cystitis in a healthy child.

BK Virus↗
PubMed1993

Dexamethasone potentiates serotonin-2 receptor-mediated intracellular Ca2+ mobilization in C6 glioma cells.

Serotonin (5-hydroxytryptamine; 5-HT) caused a transient increase in intracellular Ca2+ in C6BU-1 glioma cells in a concentration-dependent manner; half maximally at 73 nM. The 5-HT2 agonist 1-(4-iodo-2,5-dimethoxyphenyl)-2- aminopropane also increased the levels of intracellular Ca2+, whereas the 5-HT1C agonist 1-(3-chlorophenyl)piperazine and 5-HT1A agonist 8-hydroxy-2- (di-n-propylamino)tetralin were completely ineffective. Ketanserin and spiperone blocked the response to 5-HT at a nanomolar concentration, but the 5-HT3 antagonist MDL 72222 had no effect on it. Thus 5-HT2 receptors are responsible for activating Ca2+ mobilization in C6 glioma cells. Treatment of C6 glioma cells with dexamethasone potentiated the ability of 5-HT to cause intracellular Ca2+ mobilization in both a dose- and time-dependent manner. The dose-response curve for 5-HT was shifted 9-fold to the left compared to controls, and the Vmax value was also significantly enhanced. This enhanced Ca2+ mobilization was completely inhibited by ketanserin dose-dependently. In addition, the treatment with dexamethasone enhanced fluoride-activated Ca2+ mobilization, suggesting that the enhanced GTP binding protein function is one of the mechanisms responsible for the enhancement of the 5-HT response induced by dexamethasone treatment. This enhancement of agonist activity was mediated by the type II glucocorticoid receptor (GR) since RU 38486, an inhibitor of the type II GR, antagonized the dexamethasone-induced enhancement.

Amphetamines↗
PubMed1993

[Digestion method for detection of ferruginous bodies in human tissues from autopsy cases].

We compared three sodium hypochlorite digestion methods and two potassium hydroxide digestion methods for detection of ferruginous bodies in human tissues. The following results were obtained. 1. Methods using sodium hypochlorite were effective for digestion of lung tissue samples, but only in part for greater omentum tissue samples. The potassium hydroxide digestion method worked well for preparation of lung and greater omentum tissue samples. 2. Results obtained by the different digestion methods were compared by Kruskal-Wallis test and Mann-Whitney U-test. No significant difference was detected in concentrations of ferruginous bodies and naked fibers in samples of lung, and tumor and normal tissues of the greater omentum among the digestion methods. 3. A more simplified procedure for sample processing with potassium hydroxide digestion was recommended for detection of ferruginous bodies in human tissues.

Humans↗
PubMed1993

BMS-181184, a new pradimicin derivative. Screening, taxonomy, directed biosynthesis, isolation and characterization.

BMS-181184 is a new semisynthetic pradimicin derivative with a broad-spectrum antifungal activity. In a search for actinomycetes producing BMS-181184, 4 strains of Actinomadura sp. isolated from soil samples were found to produce the antibiotic under conditions of directed biosynthesis. Among them, Actinomadura sp. AB1236 proved most useful in the production of BMS-181184 when fermented in a medium containing D-serine and D-cycloserine. A minor product isolated from the broth of strain AB1236 was identified as the dexylosyl analog of BMS-181184, which was also obtained by acid hydrolysis of BMS-181184.

Actinomycetales↗
PubMed1993

Pradimicins L and FL: new pradimicin congeners from Actinomadura verrucosospora subsp. neohibisca.

Pradimicin L, a new congener of pradimicin A having the D-glucosyl-D-thomosamine moiety at the C-5 position, was isolated from Actinomadura verrucosospora subsp. neohibisca subsp. nov. The structure of pradimicin L was deduced to be N-[[(5S,6S)-5-O-[4,6-dideoxy-4-(methylamino)-3-O-(beta-D-glucopyranosyl) - beta-D-galactopyranosyl]-5,6,8,13-tetrahydro-1,5,6,9,14-pentahydroxy-11- methoxy-3-methyl-8,13-dioxobenzo[a]naphthacene-2-yl]carbonyl ]-D-alanine by MS and NMR spectrometry and degradation studies. Pradimicin FL which has the D-serine moiety instead of D-alanine was produced by directed biosynthesis in D-serine-supplemented medium. Pradimicins L and FL have a broad spectrum of in vitro antifungal activity. Pradimicin L was equiactive to pradimicin A and pradimicin FL was more active than pradimicin L.

Actinomycetaceae↗
PubMed1993

Pradimicins FS and FB, new pradimicin analogs: directed production, structures and biological activities.

Exogenous addition of D-serine to Actinomadura spinosa AA0851 resulted in directed production of pradimicin FS, a new D-serine analog of pradimicin S, together with pradimicin FB. Pradimicin FS was produced in higher yields by derivation of ferrous sulfate-resistant strains from strain AA0851. Pradimicin FB, a minor product, was identified as deglucosylpradimicin FL. Pradimicin FS was equivalent to pradimicin S in syncytium formation inhibition activity and in vitro and in vivo antifungal activities.

Actinomycetaceae↗
PubMed1993

Pradimicin S, a new pradimicin analog. II. Isolation and structure elucidation.

Pradimicin S was isolated from the culture filtrate of Actinomadura spinosa AA0851. NMR and MS analyses proved that pradimicin S is the 3'-O-(3''-O-sulfo-beta-D-glucopyranosyl) analog of pradimicin A, a new member of the pradimicin family of antibiotics. Stereochemical assignment was made by correlating pradimicin S with pradimicin L.

Actinomycetaceae↗
PubMed1993

Biosynthesis of the pradimicin family of antibiotics. I. Generation and selection of pradimicin-nonproducing mutants.

Germinated spores of Actinomadura verrucosospora subsp. neohibisca E-40, a high pradimicins producer, were mutagenized by N-methyl-N'-nitro-N-nitrosoguanidine and/or UV treatment. Thirty-seven mutants which did not produce pradimicin were selected to test for cosynthesis ability, and classified into nine classes. On the basis of their cosynthesis ability and bioconversion results, we concluded that strain JN-213 (class III) was a true converter and that strains JN-219 (class IV), JN-47 (class V) and JNU-46 (class VI) were secretors accumulating biosynthetic intermediates of pradimicin, and that strains JN-59 (class VII), JN-58 (class VIII) and JN-207 (class IX) were producers of shunt metabolites of pradimicin biosynthesis. TLC and HPLC analyses of the fermentation broths of individual strains showed that 8 new compounds were produced along with pradinone I, pradimicinone I, 11-O-demethylpradimicinone II and 7-O-methylpradimicinone II.

Actinomycetaceae↗