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Biomedical subjects

S Kawata

Publications and source records attributed to S Kawata.

12 recordsLinked to original sources
PubMed1992

Changes in lipid composition of erythrocyte membranes with administration of S-adenosyl-L-methionine in chronic liver disease.

This study was undertaken to determine whether S-adenosyl-L-methionine (SAMe) changes the lipid composition and fluidity of erythrocyte membranes in chronic liver disease. SAMe was administered intravenously at a daily dose of 600 mg for 2 weeks to 10 patients; 6 patients with cirrhosis and four with primary biliary cirrhosis. The elevated free cholesterol to phospholipid molar (C/PL) ratio of the erythrocyte membranes of the patients (0.857 +/- 0.018) significantly decreased after the administration of SAMe (1 week, 0.823 +/- 0.021; 2 weeks, 0.823 +/- 0.013). In all of the four patients whose erythrocyte membrane fluidity was measured, fluidity improved with the administration of SAMe and correlated with the C/PL ratio of the membranes. These results suggest that SAMe decreases the C/PL ratio of erythrocyte membranes and thus improves membrane fluidity in chronic liver disease.

Adult↗
PubMed1992

Effect of dietary fiber on cytochrome P450IA1 induction in rat colonic mucosa.

The effect of dietary fiber on the induction of cytochrome P450IA1 in rat colonic mucosa after a single intragastric injection of 3-methylcholanthrene (3MC, 20 mg/kg) was investigated by examining the drug-metabolizing enzyme activity, immunoblotting for cytochrome P450IA1 and immunohistochemistry. 7-Ethoxycoumarin-O-deethylase activities were approximately 20-fold higher in microsomes from both proximal and distal portions of the colonic mucosa of control diet-fed 3MC-treated rats compared with those of control diet-fed untreated rats. Strong immunofluorescence for cytochrome P450IA1 was localized in the cytoplasm of the colonic mucosa surface epithelium from the control diet-fed 3MC-treated rats. 7-Ethoxycoumarin-O-deethylase activity and cytochrome P450IA1 content determined by immunoblotting were significantly lower in wheat bran-fed 3MC-treated rats than in control diet-fed 3MC-treated rats. Immunohistochemical analysis showed much weaker immunofluorescence for cytochrome P450IA1 in the surface epithelium of the colonic mucosa of the wheat bran-fed 3MC-treated rats. These observations suggested that dietary fiber can affect the induction of cytochrome P450IA1 in colonic mucosa by dietary inducers or carcinogens.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1992

Elevated levels of plasma transforming growth factor-beta in patients with hepatocellular carcinoma.

We measured the plasma transforming growth factor-beta (TGF-beta) concentration in 14 patients with human hepatocellular carcinoma (HCC) and 9 age-matched normal subjects using growth inhibition assay of mink lung epithelial cells. The calculated plasma TGF-beta concentration in the patients with HCC was 28.6 +/- 27.9 ng/ml (mean +/- SE), showing significant elevation compared with that in 9 normal subjects (5.3 +/- 3.3 ng/ml, P less than 0.01). In three cases, we could measure plasma TGF-beta levels before and after their treatment for HCC. The plasma TGF-beta levels decreased from 59.0 to 18.2 ng/ml after hepatic resection in one case, and from 24.0 to 10.7 ng/ml and from 12.4 to 3.4 ng/ml after transhepatic arterial embolization in the other two cases. These data indicate that plasma TGF-beta level is elevated in patients with HCC, probably due to release from HCC tissues.

Animals↗
PubMed1992

Effect of pravastatin, a potent 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, on survival of AH130 hepatoma-bearing rats.

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor is known to have an inhibitory effect on cell growth in addition to a cholesterol-lowering effect. This study examined the effect of pravastatin, a potent inhibitor of HMG-CoA reductase, on the survival of AH130 hepatoma-bearing rats. Pravastatin (1, 2, or 8 mg/kg body weight) was intraperitoneally injected once a day into tumor-bearing rats. The difference in the survival curves was significant between the controls and the rats treated with 8 mg/kg of pravastatin (P < 0.019 by logrank test) but not between the controls and the rats treated with 1 or 2 mg/kg of the inhibitor. The tumor volume was significantly decreased in the rats treated with 8 mg/kg of pravastatin (P < 0.05). These observations showed that intraperitoneal injection of pravastatin could improve the survival of AH130 hepatoma-bearing rats and had an inhibitory effect on the growth of the ascites form tumor.

Animals↗
PubMed1992

Application of the environmental SEM in human dentin bleached with hydrogen peroxide in vitro.

The environmental SEM (E-SEM) can be used unfixed biological samples under a low vacuum and wet condition. In this study, the fractured dentin of unfixed human teeth was treated with a 30% hydrogen peroxide solution (H2O2) for the examination of tooth-bleaching prior to the E-SEM and a conventional SEM. The peritubular matrix (PM) always showed a few cracks along the long axis of a dentinal tubule, and the ends of fine fibrils rose to the smoothly changed surface of the intertubular matrix (IM). The E-SEM with non-fixation and the conventional SEM following fixation indicated that the hydrogen peroxide solution easily permeated the PM and dissolved the non-fibrillar substance including the cracks of the PM by the constriction. In the IM, the solution may partially dissolve the organic parts within mineralized fibrils as well as non-fibrillar substance between the fibrils, although these remnants might precipitate again there.

Adolescent↗
PubMed1979

Adjuvant activities in production of reaginic antibody by bacterial cell wall peptidoglycan or synthetic N-acetylmuramyl dipeptides in mice.

This paper is concerned with the adjuvant activity in stimulatory immunoglobulin E production against ovalbumin (OA) by bacterial cell walls, cell wall peptidoglycan (PG), and their PG fragments and synthetic N-acetylmuramyl (MurNAc) dipeptides in A/J mice. A PG isolated from Streptococcus pyogenes, PG subunit polymer and dimer obtained from Staphylococcus epidermidis, and water-soluble fragments of cell walls or PG prepared from Nocardia corynebacteriodes and Streptomyces gardneri were found to enhance both the primary and secondary responses of anti-OA immunoglobulin E antibody production. It was suggested that the PG portion, either intact or highly degraded, was capable of enhancing the immunoglobulin E antibody production, and there was no need for the non-PG moiety or intactness of PG structure for the adjuvant activity. This finding was confirmed and extended by the use of synthetic MurNAc dipeptides. Among eight MurNAc dipeptides tested, MurNAc-l-Ala-d-isoGln, MurNAc-l-Ala-d-Gln, MurNAc-l-Ala-d-Glu, and MurNAc-l-Ser-d-isoGln were found active as an adjuvant in the stimulation of the primary and secondary reaginic anti-OA antibody production in a similar way to the cell wall PG and their fragments. None of the synthetic MurNAc-l-Ala-l-isoGln, MurNAc-l-Ala-l-Gln, MurNAc-l-Ala-l-Glu, and MurNAc-l-Ala-d-isoAsn, on the other hand, stimulated the anti-OA immunoglobulin E antibody production in either primary or secondary response, indicating the importance for the adjuvancy in immunoglobulin E production of the configuration of the glutamic acid residues adjacent to the l-Ala (or l-Ser) in muramyl dipeptides.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1979

Macrophage activation by bacterial cell walls and related synthetic compounds.

Activation of peritoneal macrophages from guinea pigs by various bacterial cell walls, M-1 endo-N-acetylmuramidase enzymatically digested bacterial cell walls and synthetic muramyl dipeptides was studied in terms of stimulation of [14C] glucosamine incorporation. All test bacterial cell wall preparations significantly increased a [14C]glucosamine uptake by the macrophages. Some of the water-soluble M-1 enzyme digests also exerted stimulating effects on macrophages, although the activity of the digests was found to be weaker than those of original cell walls. Furthermore, an adjuvant-active synthetic MurNAc-L-Ala-D-isoGln (MDP) showed a weak but significant activity, whereas an adjuvant-inactive analog, MurNAc-L-Ala-L-iso-Gln, did not show a significant activity, at least with the dose of 100 microgram. Additional studies with 6-O-acyl derivatives of MDP revealed that 6-O-(2-tetradecylhexadecanoyl)-MDP and 6-O-(3-hydroxy-2-tetradecyl-octadecanoyl)-MDP exhibit stronger macrophage-stimulating effects than MDP. It can be concluded from the above findings that MDP is the essential structure responsible for stimulating the activity of cell walls on guinea pig peritoneal macrophages, but it requires a particle state, which results from an additive character of lipophilicity, to exert the activity fully and effectively.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1979

Mitogenic effects of bacterial cell walls, their fragments, and related synthetic compounds on thymocytes and splenocytes of guinea pigs.

Stimulation of [(3)H]thymidine incorporation of thymocytes and splenocytes from guinea pigs by various bacterial cell walls and their peptidoglycans, by enzymatic digests, and by synthetic muramyl dipeptides was studied as an indication of mitogenic activity. Cell wall and peptidoglycan preparations, isolated from 19 strains belonging to 18 different species, definitely increased [(3)H]thymidine incorporation of thymocytes as well as splenocytes, regardless of mycolic acid contents as a non-peptidoglycan component. Both the cell walls from Nocardia corynebacteriodes (containing mycolic acids) and those from Streptomyces gardneri (lacking mycolic acids) showed far stronger mitogenic activities on splenocytes than other cell walls (stimulation index, 25 to 30). Furthermore, water-soluble enzymatic digests, notably the endopeptidase digests, which generally were greater in degree of polymerization of peptidoglycan subunits than the glycosidase digests obtained from representative cell walls, were found to have as distinct a stimulating activity on splenocytes as the original cell walls. In contrast, solubilization of the cell walls by enzymes, irrespective of endopeptidases or glycosidases, was accompanied by disappearance of the mitogenic activity on thymocytes. On the other hand, studies with synthetic 6-O-acyl-MurNAc-l-Ala-d-isoGln preparations (6-O-acyl-MDPs) revealed that 6-O-stearoyl-MDP and 6-O-(2-tetradecylhexadecanoyl)-MDP, unlike MDP, had distinct mitogenic activity on thymocytes, whereas their activity on splenocytes was rather weaker than MDP itself. The findings presented here suggest that MDP is the minimal structure for the mitogenic activities of bacterial cell walls on guinea pig splenocytes, but that MDP, though distinctively active by itself, requires a polymerized form to exert effectively its inherent stimulating activities on splenocytes. On the other hand, on thymocytes, MDP, unless it takes a particular form or has appropriate additive groups, cannot exert its mitogenic activities.

Acetylmuramyl-Alanyl-Isoglutamine↗