Biomedical subjects

Y Sakagami

Publications and source records attributed to Y Sakagami.

At least 91 records · Page 5Linked to original sources

PubMed1988

Release of peptide leukotrienes from rat Kupffer cells.

Kupffer cells isolated from the normal rat liver were incubated with calcium ionophore A23187, and the levels of peptide leukotrienes (LTC4, LTD4, and LTE4) contained in the culture supernatant were determined by the combined technique of reverse-phase high-performance liquid chromatography and radioimmunoassay. In response to A23187, Kupffer cells released LTC4, LTD4, and LTE4. After 10 min-preincubation of Kupffer cells with AA861, a 5-lipoxygenase inhibitor, the generation of LTC4, LTD4, and LTE4 from A23187-stimulated Kupffer cells was significantly suppressed. Platelet activating factor (PAF), a phospholipid mediator, significantly enhanced the release of LTC4, LTD4, and LTE4 from Kupffer cells stimulated with A23187. These results suggested that Kupffer cells may participate in inflammatory and immunologic events in the liver tissue by the release of peptide leukotrienes.

Animals↗

PubMed1988

Structure of cCF10, a peptide sex pheromone which induces conjugative transfer of the Streptococcus faecalis tetracycline resistance plasmid, pCF10.

The peptide pheromone, cCF10, which induces aggregation and high frequency plasmid transfer in Streptococcus faecalis cells carrying the tetracycline resistance plasmid, pCF10, was isolated and its structure determined. The molecular weight of cCF10 is 789, and its amino acid sequence is H-Leu-Val-Thr-Leu-Val-Phe-Val-OH. Pheromone activity, as determined by a clumping induction assay, was detectable at a concentration of 2.5 x 10(-11) M. A peptide of the same sequence as that of the cCF10 produced by S. faecalis cells was synthesized by the liquid-phase method. The synthetic pheromone showed biological activity and chromatographic behavior that was identical to that of the cCF10 of bacterial origin. When the response of S. faecalis cells to various concentrations of synthetic cCF10 was monitored by measuring both the frequency of plasmid transfer and the synthesis of pheromone-inducible antigens, an excellent correlation was observed between donor ability and the appearance of a 150-kilodalton protein that appears to be involved in formation of mating aggregates. The dose-response data in the range of concentrations where the amount of pheromone became limiting (10(-11)-10(-12) M) were consistent with the notion that as few as one or two molecules per donor cell may be sufficient to induce a mating response.

Amino Acid Sequence↗

PubMed1988

Effects of the polysaccharide chain of lipopolysaccharide in an experimental massive hepatic cell necrosis model.

When small amounts (1 microgram) of lipopolysaccharide (LPS) purified from Salmonella minnesota (SM) wild, SM R60 and SM R345 were intravenously injected into mice 7 days after heat-killed Propionibacterium acnes was intravenously injected, massive hepatic cell necrosis was induced and most of the mice died within 24 hours. However, when LPS from SM R345 treated galactosidase, SM R5 and SM R7 and lipid A from SM R595 were administered, the survival rate was much higher and no histological changes of the liver such as necrosis could be seen in any of the mice. In each of the LPS used in this study, the structure of the polysaccharide chain was different and it was shorter in the following order: SM wild----SM R60----SM R345----SM R345 treated with galactosidase----SM R5----SM R7----SM R595. This suggests that the polysaccharide chain of LPS plays an important role in the induction of massive hepatic cell necrosis in this experimental model.

Animals↗

PubMed1988

Effects of an anti-tumor polysaccharide, schizophyllan, on interferon-gamma and interleukin 2 production by peripheral blood mononuclear cells.

We examined the effect of schizophyllan, a neutral glucan isolated from the culture filtrate of Schizophyllum commune Fries, on the production of interferon-gamma (IFN-gamma) and interleukin 2 (IL 2) from the mitogen-stimulated human peripheral blood mononuclear cells (PBMC). When the levels of IFN-gamma and IL 2 in the culture medium of phytohemagglutin (PHA)- or concanavalin A (Con A)-stimulated PBMC were measured by radioimmunoassay and enzyme-linked immunosorbent assay (ELISA) respectively, a significant increase in the production of both cytokines by schizophyllan was demonstrated. These results suggest that the increased production of IFN-gamma and IL 2 may be responsible for the anti-tumor activity of this glucan.

Concanavalin A↗

PubMed1988

Effects of the polysaccharide chain of lipopolysaccharide in an experimental massive hepatic cell necrosis model in the mice.

When a small amount (1 microgram) of lipopolysaccharide (LPS) purified from Salmonella minnesota wild, Salmonella minnesota R60, and Salmonella minnesota R345 was intravenously injected into mice 7 days after heat-killed Propionibacterium acnes was intravenously injected, massive hepatic cell necrosis was induced and most of the mice died within 24 hours. However, when LPS from Salmonella minnesota R5 and Salmonella minnesota R7 and lipid A from Salmonella minnesota R595 were administered, the survival rate was much higher and no histological changes in the liver such as necrosis could be seen in any of the mice. In each of the LPS used in this study, the structure of the polysaccharide chain was different, and it decreased in the following order: Salmonella minnesota wild----Salmonella minnesota R60----Salmonella minnesota R345----Salmonella minnesota R5----Salmonella minnesota R7----Salmonella minnesota R595. This suggested that the polysaccharide chain of LPS played an important role in the induction of massive hepatic cell necrosis in this experimental model.

Animals↗

PubMed1988

Protective effects of a leukotriene inhibitor in an experimental massive hepatic cell necrosis model.

When heat-killed Propionibacterium acnes was intravenously injected into mice and seven days later, a small amount of gram-negative lipopolysaccharide was also intravenously injected, most of them died of massive hepatic cell necrosis. However, when azelastine hydrochloride, a leukotriene antagonist chemically known as 1(2H)-phthalazinone, 4-[(4-chlorophenyl)methyl]-2-(hexahydro-1-methyl-1H-azepine-4-yl)-, monohydrochloride, or AA861, 2-(12-hydroxydodeca-5, 10-diynyl)-3,5,6-trimethyl-1, 4-benzoquinone, a specific inhibitor of 5-lipoxygenase, was administered during this experimental induction of massive hepatic cell necrosis, the survival rate of the mice increased and the histological changes of the liver improved remarkably. These results suggested that leukotriene may be important for the induction of massive hepatic cell necrosis in our experimental model.

Animals↗

PubMed1988

Tryptophan metabolism in D-galactosamine-induced liver injury.

We have reported that in rats with D-galactosamine-induced liver injury, the serum level of indoleacetic acid (IAA), a metabolite of tryptophan (TRP), increases before the increase in serum transaminase activity. To determine whether this IAA is derived from hepatocytes, isolated hepatocytes were treated with D-galactosamine and loaded with TRP, and the changes in TRP and IAA levels in the culture supernatant of the isolated hepatocytes were measured at various time intervals. As a result, IAA level in the culture supernatant of hepatocytes treated with D-galactosamine and loaded with TRP significantly increased in a time-dependent manner. This indicates that in D-galactosamine-induced liver injury, a metabolic pathway which produces IAA from TRP through tryptamine is present in hepatocytes.

Animals↗

PubMed1988

Determination of serum cholestatic factor level by ELISA in drug-induced allergic hepatitis.

We have shown that intrahepatic cholestasis often observed in drug-induced allergic hepatitis may be induced by a kind of lymphokine, the cholestatic factor (CF). In this study, we measured the CF level in the serum of patients with jaundice by ELISA using anti-CF monoclonal antibody. As a result, CF was detected in the serum of most of the patients at the peak of jaundice, but it was not detected when the patients were recovering from jaundice. When the changes in the serum CF level were followed during the clinical course of a patient, it reached its maximum level before that of the serum total bilirubin level and quickly decreased thereafter. These results also suggest that intrahepatic cholestasis in drug-induced allergic hepatitis may be induced by CF.

Adult↗

PubMed1988

Effects of recombinant interleukin 2 on immunological effector cells of the peripheral blood in patients with HBe antigen-positive chronic hepatitis.

Changes in peripheral blood immunological effector cells after systemic administration of recombinant interleukin 2 (rIL2) were studied in 14 patients with HBe antigen-positive chronic hepatitis. The patients were intravenously injected with rIL2 for 4 weeks, and the experiments were performed using mononuclear cells isolated from the peripheral blood during and after rIL2 administration. No significant changes in OKT4-positive cell population, OKT8-positive cell population, OKT4/OKT8 ratio and Leu7-positive cell population were detected during and after intravenous injection of rIL2. However, the natural killer (NK) cell and lymphokine-activated killer (LAK) cell activities significantly increased in the fourth week of rIL2 administration, while the K cell activity in the antibody-dependent cell-mediated cytotoxicity reaction, antibody response, lectin-induced lymphocyte transformation and IL1 production of LPS-stimulated monocytes were not affected. These results suggest that IL2 increases the NK cell and LAK cell activities in vivo.

Adult↗

PubMed1988

Experimental immunological intrahepatic cholestasis model.

Heat-killed Propionibacterium acnes (P. acnes) was intravenously injected into tuberculin-sensitized guinea pigs, and 7 days later, purified protein derivative (PPD) was also injected intravenously resulting in marked reductions in bile flow and bile acid excretion. Serum levels of bile acids and cholesterol were increased, and the activities of alkaline phosphatase (ALK-p) and leucine aminopeptidase (LAP) were also elevated. Histological examination revealed dilatation of bile canaliculi and diminution of microvilli. These results indicated that intrahepatic cholestasis was induced. These pathological changes were not detected in guinea pigs in which PPD was not injected. In this experimental model, the tuberculin-sensitized lymphocytes were infiltrated into the liver by P. acnes injection and the cholestatic factor was produced by PPD injection, resulting in the induction of intrahepatic cholestasis.

Animals↗

PubMed1988

DNA repair test of disinfectants by liquid rec-assay.

The DNA-damaging capacity and the mutagenicity of 6 disinfectants were studied by liquid rec-assay and Ames test. 5 disinfectants were found to be positive in DNA-damaging capacity while only one of them showed clear mutagenicity in the Ames test. Liquid rec-assay by direct incubation with S9 mix was the most sensitive method and gave the best correlation between the growth ratio (R 50) and the time lag, both of which compared Rec+ and Rec-. Liquid rec-assay may be useful for detecting the DNA-damaging capacity of chemicals with a strong killing effect.

Bacillus subtilis↗

PubMed1988

Determinations of the DNA sequence of the mreB gene and of the gene products of the mre region that function in formation of the rod shape of Escherichia coli cells.

The 6.5-kilobase mre region at 71 min in the Escherichia coli chromosome map, where genes involved in formation of a rod-shaped cell form a gene cluster, was analyzed by in vivo protein synthesis in a maxicell system and by base sequencing of DNA. An open reading frame that may code for a protein with an Mr of about 37,000 on sodium dodecyl sulfate-polyacrylamide gels was found and was correlated with the mreB gene. N-terminal amino acid sequencing of the hybrid mreB-lacZ protein confirmed the production by mreB of a protein of 347 amino acid residues with a molecular weight of 36,958. The amino acid sequence of this protein deduced from the DNA sequence showed close similarity with that of a protein of the ftsA gene which is involved in cell division of E. coli. Three other contiguous genes that formed three proteins with Mrs of about 40,000, 22,000, and 51,000, respectively, were detected downstream of the mreB gene by in vivo protein synthesis. The mreB protein and some of these three proteins may function together in determination of cell shape.

Amino Acid Sequence↗

PubMed1988