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Biomedical subjects

K Tabata

Publications and source records attributed to K Tabata.

At least 37 records · Page 2Linked to original sources
PubMed1995

Evaluation of intestinal absorption into the portal system in enterohepatic circulation by measuring the difference in portal-venous blood concentrations of diclofenac.

PURPOSE: We evaluated the first-pass effects in vivo by the intestine and liver during enterophepatic circulation (EHC) by simultaneously measuring the portal and venous plasma concentrations of the rat. METHODS: The venous and upper portal blood vessels were cannulated through the jugular and the pyloric veins, respectively, to obtain simultaneously blood samples from both sites. After diclofenac was injected as a bolus through the jugular vein, the concentrations of diclofenac in the portal and jugular veins were measured at time intervals. The absorption rate from the intestinal tract into the portal system was determined using the portal-venous difference in plasma concentrations of diclofenac, considering 40% partitioning of diclofenac into erythrocytes. RESULTS: After one hour, the plasma concentration in the portal vein was always higher than that in the jugular vein in awakening rats with intact EHC (portal-venous blood concentration difference). No portal-venous difference was observed in awakening rats with bile-duct cannulation. Therefore, it was concluded that this portal-venous concentration difference was not due to the hepatic clearance but to diclofenac reabsorption from the intestinal tract. CONCLUSIONS: Approximately 40% of the dose of diclofenac was reabsorbed over 8 hours from the intestinal tract into the portal system. By comparing the reabsorbed amounts in the portal system and in the systemic circulation, the hepatic extraction ratio in vivo (FH) of diclofenac was estimated to be 63%.

Animals↗
PubMed1995

Epitope analysis using anti-oligosaccharide (G4) monoclonal antibody.

A murine monoclonal antibody recognizing (1-->6)-beta-D-glucopyranosyl laminaritriose (G4) was prepared by immunizing BALB/c mice with G4-bovine serum albumin conjugate and fusing the splenocytes with mouse myeloma cells. The monoclonal antibody (IgM) provoked by the cloned cells showed low reactivity with schizophyllan, an antitumor polysaccharide, but notable reactivity with some low-molecular-weight schizophyllans. This antibody was useful for determination of the epitope of several polysaccharides. The extent of reactivity of this monoclonal antibody was related only to the molecular weight of schizophyllan.

Animals↗
PubMed1995

Influence of laparotomy on disposition kinetics of diclofenac in CCl4-intoxicated rats.

The effect of the acute hepatic failure induced by CCl4 on the pharmacokinetics of diclofenac, which is definitely subject to enterohepatic circulation (EHC) in normal rats, was evaluated. This hepatic failure extinguished the secondary peak on the plasma time course which is usually observed in normal rats due to EHC. In the group without EHC by means of bile cannulation, the total clearance (CL) markedly decreased by CCl4-intoxication from 0.7 l/h/kg down to 0.1 l/h/kg, and mean residence time (MRT) increased from 0.29 h up to 2.8 h. The plasma time curves of the rats with laparotomy and with bile duct-cannulation were almost the same in the CCl4-intoxicated group. The bile excretion ratio of diclofenac markedly decreased by CCl4-intoxication from 43% down to 13%. In both groups, 92% of the total diclofenac excreted into the bile was glucuronide. While EHC made area under the curve (AUC) and MRT obviously increase in the CCl4-free rats, the effect of EHC on these moments was negligible in the CCl4-intoxicated rats. In the CCl4-intoxicated condition, the elimination of diclofenac in the rats with laparotomy was considerably slower than that in the rats without laparotomy. The plasma time courses were obviously monoexponential in the former group, while those were almost biexponential in the latter group.

Animals↗
PubMed1995

Water-soluble viscous substance of Jew's mellow leaves lowers serum and liver cholesterol concentrations and increases fecal steroid excretion in rats fed a high cholesterol diet.

The effect of Jew's mellow leaf powder and its water soluble viscous substance on cholesterol metabolism in rats fed a high cholesterol diet was examined. When compared to the controls, total serum and liver cholesterol concentrations were significantly decreased or tended to decrease in the groups given dry powder of fresh Jew's mellow leaves, dry powder purchased from the market or residual powder after extracting with ethanol, whereas no difference was observed in those given residual powder after extracting with water. There were significant increases or increasing tendencies in the fecal excretion of bile acids, total neutral sterols and cholesterol in those fed the experimental diets when compared to the control group. Rats fed a diet containing a water-soluble viscous substance (1.7%, about 1% as dietary fiber) obtained from the dry powder of Jew's mellow leaves showed significant decreases in serum and liver cholesterol concentrations and increases in fecal excretions of bile acids and neutral sterols. Based on the above, the component of dry powder of Jew's mellow leaves that is effective in decreasing serum and liver cholesterol concentrations was found to be a soluble dietary fiber, and the mechanism was assumed to be largely due to the increased excretion of bile acids and neutral sterols.

Animals↗
PubMed1994

Molecular cloning and sequence analysis of the proBA operon from an extremely thermophilic eubacterium Thermus thermophilus.

A 3.6 kb DNA fragment carrying the Thermus thermophilus proBA region, which encodes the first two steps in the proline biosynthetic pathway, was cloned from the Thermus thermophilus gene library, and its complete nucleotide sequence was determined. The deduced amino acid sequence of gamma-glutamyl kinase (40,657 Da), the product of proB gene, and gamma-glutamyl phosphate reductase (48,747 Da), the product of proA gene, showed 44.1% and 44.4% identity to those of Escherichia coli, respectively. The termination codon of the proB gene and the initiation codon of the proA gene overlapped by 2 bp. A possible transcriptional termination structure was found downstream of the proA gene but not downstream of the proB gene. These results indicate that the proBA genes of T. thermophilus form a single operon as in E. coli.

Aldehyde Oxidoreductases↗
PubMed1994

An antitumor, branched (1-->3)-beta-D-glucan from a water extract of fruiting bodies of Cryptoporus volvatus.

A water-soluble, (1-->6)-branched (1-->3)-beta-D-glucan (H-3-B) was isolated from a hot-water extract of the fruiting bodies of the fungus, Cryptoporus volvatus (Basidiomycetes). Enzymatic analysis using exo-(1-->3)-beta-D-glucanase and methylation analysis indicated that this polysaccharide has a main chain composed of beta-(1-->3)-linked D-glucopyranosyl residues, and single, beta-(1-->6)-linked D-glucopyranosyl residues attached as side chains to, on average, every fourth sugar residue of the main chain. This structure was confirmed by 13C NMR spectra of the glucan in Me2SO-d6. The weight-average molecular weight (Mw) of H-3-B was determined to be 44.0 x 10(4) by gel permeation chromatography equipped with a low-angle laser-light-scattering photometer. The electron microscopic observations showed that H-3-B and its sonicated sample (S-H-3-B, Mw = 13.7 x 10(4)) can be described as linear worm-like chains. The mass per unit length for native and sonicated H-3-B was determined to be 1750 and 1780 g mol-1 nm-1, respectively, from the contour lengths obtained by electron microscopy and the molecular weights. These values are in good agreement with that expected for the triple stranded structure. A sample denatured in 0.1 M NaOH and subsequently renatured by neutralization showed a mixture of linear and cyclic structures, and larger aggregates with less well-defined morphology. The H-3-B and S-H-3-B had antitumor activity against the Sarcoma 180 tumor.

Animals↗
PubMed1994

A carotenogenic gene cluster exists on a large plasmid in Thermus thermophilus.

In Thermus thermophilus HB27, the crtB gene encoding phytoene synthase was found to exist on the large plasmid, pTT27. One of the carotenoid under-producing mutants, Crt31, carried a derivative of pTT27 (pTT27') in which deletion and inversion were observed near the crtB gene. T. thermophilus HB8 also contained a large plasmid which showed homology to pTT27 and the crtB gene. These results suggested that genes for carotenoid biosynthesis occurred as a cluster on a large plasmid in Thermus thermophilus. This is the first report to show directly that carotenogenesis is plasmid-encoded in microorganisms.

Alkyl and Aryl Transferases↗
PubMed1994

Molecular cloning and sequence analysis of the proC gene encoding delta 1-pyrroline-5-carboxylate reductase from an extremely thermophilic eubacterium Thermus thermophilus.

A gene library of the extremely thermophilic bacterium, Thermus thermophilus HB27, was constructed in Escherichia coli, and recombinant plasmids able to complement proC mutants of HB27 were obtained. Using the plasmids, the complete nucleotide sequence of the proC gene encoding delta 1-pyrroline-5-carboxylate reductase (P5CR) [EC 1.5.1.2] was determined. The deduced amino acid sequence showed a significant homology to those of P5CRs of E. coli, soybean and human. The proC gene of T. thermophilus was expressed in E. coli and the activity of heat-resistant P5CR was determined. The mutation sites of two HB27 proC mutants were also determined.

Amino Acid Sequence↗
PubMed1994

An improved sandwich ELISA method for the determination of immunoreactive schizophyllan (SPG).

As it is important to determine the optimal serum concentration of schizophyllan (SPG) when it is used as an anti-cancer drug, we devised a solid-phase ELISA. We also developed a sandwich ELISA using murine anti-SPG monoclonal antibody as the first antibody and rabbit anti-SPG serum as the second antibody in order to improve the detection sensitivity. This assay was able to determine SPG concentrations over 1.0 ng/ml and the absorbance at 490 nm was directly proportional to the SPG concentration. SPG in rabbit serum, obtained after intravenous and intramuscular injection (SPG; 10 mg/kg), was determined by this sandwich ELISA. Furthermore, the sensitivity of this ELISA method was compared with that of the Limulus test. The Limulus test is able to detect SPG in physiological saline (pH 6.3) at concentrations greater than 1.0 microgram/ml, but the sensitivity increased when SPG was dissolved in alkaline solution (pH 12.0), enabling SPG to be measured almost down to 1.0 ng/ml. These data suggest that our sandwich ELISA may be used for the measurement of SPG in blood or tissue.

Animals↗
PubMed1994

Monoclonal antibody to proteoglycan derived from Grifola frondosa (Maitake).

A murine monoclonal antibody (MAb) was prepared by immunizing BALB/c mice with a proteoglycan fraction derived from Grifola frondosa (Maitake mushroom), followed by the hybridization of spleen cells with mouse myeloma cells. The MAb (subclass; Ig G2b), designated MPG2, reacted with schizophyllan (SPG), curdlan, scleroglucan, laminarin and lentinan, but not with dextran, pullulan, mannan and xylan. Immunohistochemistry (ABC-GO method) showed that MAb MPG2 reacted with lysosomal proteoglycan and (1-->6)-beta-branched laminaritriose taken up by rabbit peritoneal macrophages. These results suggest that this MAb may recognize mainly (1-->3)-beta-D-glucan, and may be useful for determining the immunological properties of Grifola frondosa-derived proteoglycan.

Animals↗
PubMed1994

The inhibitory effect of sulfated schizophyllans and related oligosaccharides on coagulation and fibrinolysis.

Sulfated schizophyllans and sulfated oligosaccharides were prepared and their inhibitory effects on coagulation and fibrinolysis were examined. Some sulfated schizophyllans, which had a sulfur content of more than 10%, prolonged prothrombin time (PT) and thrombin time (TT). Interestingly, some sulfated schizophyllans and related oligosaccharides were able to inhibit plasmin toward fibrinolysis and amidolysis.

Amino Acid Sequence↗
PubMed1994

Construction of a new teichuronopeptide-defective derivative from alkaliphilic Bacillus sp. C-125 by cell fusion.

Cell walls of facultative alkaliphilic Bacillus sp. C-125 are composed of peptidoglycan, teichuronic acid, and teichuronopeptide. A mutant lacking teichuronic acid, or defective in both teichuronic acid and teichuronopeptide has been isolated from the organism. We now constructed another type of a cell-wall defective mutant that was defective in teichuronopeptide but had teichuronic acid, by cell fusion using protoplasts prepared from a wild-type strain and a mutant defective in teichuronopeptide and teichuronic acid. This mutant grew more poorly than wild type or a teichuronic acid-defective strain of C-125. The growth, however, was faster than that of the parental strain defective in both teichuronic acid and teichuronopeptide.

Bacillus↗
PubMed1994

[A case of "forme fruste" of tuberous sclerosis having been treated as genuine epilepsy].

A 30-year-old man had signs of a lumbosacral skin plaque, called "shagreen patch", and mental retardation. He had been treated as genuine epilepsy for more than twenty years. Neither significant abnormalities nor facial angiofibroma (adenoma sebaceum) were detected on physical and neurological examinations. Brain CT revealed calcified subependymal nodules. A T2-weighted brain MRI presented high signal intensity regions affecting the cerebral cortex, which suggested tuberous lesions. Echocardiography showed high echoic lesions on the left ventricular wall and papillary muscles, suggesting calcification. The case was diagnosed as suffering from "forme fruste" of tuberous sclerosis. The three criteria typical of tuberous sclerosis (facial angiofibroma, seizure and mental retardation) were not satisfied. The "forme fruste" variant is less known, because the pattern of involvement varies, and it may clinically simulate genuine epilepsy.

Adult↗
PubMed1993

Physical map of the extremely thermophilic bacterium Thermus thermophilus HB27 chromosome.

The physical map of the chromosome of Thermus thermophilus HB27 was constructed using three restriction enzymes; EcoRI, SspI and MunI by applying pulsed-field gel electrophoresis techniques. Although the genome size of 1.82 Mb was almost the same as that (1.74 Mb) reported for T. thermophilus HB8 [Borges, K.M., and P.L. Bergquist. (1993) J. Bacteriol. 175, 103-110], the MunI cleavage maps were different. A 240 kb plasmid was detected in HB27, and its physical map was also constructed. In addition, several genes were located on the chromosomal physical map.

Chromosome Mapping↗
PubMed1993

Augmentation of protective immune responses against Sendai virus infection by fungal polysaccharide schizophyllan.

When treated with fungal polysaccharide schizophyllan, mice survived otherwise lethal Sendai virus infection. Both intraperitoneal and oral administrations were effective when sonicated schizophyllan with a relative molecular mass (M(r)) of 4.6 x 10(5) was used. Antiviral antibody in the serum could be detected at an earlier time after virus infection and virus spread in the lung was more efficiently inhibited in schizophyllan-treated mice than in untreated controls. Schizophyllan also augmented protective immune responses induced by low doses of a live Sendai virus vaccine that were insufficient to confer complete protection against challenge infection with a virulent strain. On the other hand, schizophyllan did not influence interferon production in mice whether or not infected with Sendai virus. The present results suggest that schizophyllan confers better protection against virus infection through augmentation of antiviral immune responses and can be used as an immune enhancer.

Adjuvants, Immunologic↗
PubMed1993

Detection of immunoreactive schizophyllan by solid-phase enzyme-linked immunosorbent assay.

In order to detect immunoreactive schizophyllan (SPG), one of the beta-1,3-glucans in solution, a murine anti-schizophyllan monoclonal antibody, SPG1-HS, was used as a primary antibody for solid-phase enzyme-linked immunosorbent assay (ELISA). Polysaccharide-bovine serum albumin (BSA), and polysaccharide-bovine hemoglobin (Hb) conjugate were prepared as an antigen. The absorbance at 490 nm in ELISA was directly proportional to the SPG concentration in SPG-BSA or SPG-Hb conjugates, allowing the accurate measurement of SPG at concentrations of more than 1.0 microgram/ml. Also, this ELISA detected SPG in SPG-BSA and SPG-Hb conjugates in human serum in a similar manner. These results suggest that this ELISA is applicable for the determination of SPG concentration in SPG-BSA and SPG-Hb conjugates in human tissue and blood.

Animals↗
PubMed1993

Aquastatin A, an inhibitor of mammalian adenosine triphosphatases from Fusarium aquaeductuum. Taxonomy, fermentation, isolation, structure determination and biological properties.

A new inhibitor of mammalian adenosine triphosphatases, designated aquastatin A, has been isolated from a fungus identified as Fusarium aquaeductuum. The structure of this compound has been determined by MS and NMR analyses. It inhibits Na+/K(+)-ATPase with an IC50 value of 7.1 microM, and H+/K(+)-ATPase with an apparent IC50 value of 6.2 microM.

Adenosine Triphosphatases↗