Koji Yashiro

Asahi University, Gihu, Gifu, Japan

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Publications (26)41.49 Total impact

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    ABSTRACT: Although CD57+ lymphocytes are closely correlated with prognosis in various cancers, the role of subsets of CD57+ cells in hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC) is unclear. In the present study, peripheral blood (PB) from HCV-related HCC patients was analyzed. Plasma cytokine levels and in vitro cytokine-producing capabilities were analyzed with enzyme-linked immunosorbent assays, and CD57+ cell subsets were studied using a multi-color FACS system. Interferon (IFN)-γ was undetectable in the plasma of patients with tumors at any stage, whereas the plasma levels of tumor necrosis factor (TNF)-α, interleukin (IL)-10 and IL-18, but not that of IL-12, were significantly higher in stage IV patients compared to patients with earlier-stage tumors. In contrast, the IFN-γ-producing capability of PB was highest in stage I patients and gradually decreased with tumor progression. The IL-10-, IL-18- and IL-12-producing capabilities of PB increased from stage I to III. However, PB-TNF-α, IL-10- and IL-18-producing capabilities were reduced in stage IV patients, probably due to repeated anti-cancer treatments. The percentage of CD4+CD57+αβTCR+ cells (CD4+CD57+ T cells) in peripheral blood lymphocytes (PBLs) increased with tumor progression. Moreover, the percentage of CD4+CD57+ T cells in PBLs and the ratio of CD4+CD57+ T cells to CD4+αβTCR+ cells (CD4+ T cells), but not that of CD4+CD57+ T cells to CD57+αβTCR+ cells (CD57+ T cells), showed a significant inverse correlation with PB-IFN-γ-producing capability. The present results suggest that an increase in CD4+CD57+ T cells controls the capability of PB to produce the anti-tumor cytokine IFN-γ and that PB-IFN-γ production is impaired with HCC tumor progression.
    Oncology Reports 07/2011; 26(1):201-8. DOI:10.3892/or.2011.1258 · 2.19 Impact Factor
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    ABSTRACT: The activities of Se-dependent glutathione peroxidases and non-Se-dependent glutathione peroxidase in the submandibular gland were observed using specific substrates. The activities for H2O2, cumene hydroperoxide, tert-butyl hydroperoxide, and phosphatidylcholine hydroperoxide were strongly inhibited by iodoacetate. After correction for the activity toward cumene hydroperoxide, it was shown that cumene hydroperoxide is mainly reduced by cytosolic glutathione peroxidase. Although the specific activity was lower than that of cytosolic glutathione peroxidase, phospholipid hydroperoxide glutathione peroxidase showed activity toward not only phosphatidylcholine hydroperoxide but also phosphatidylethanolamine hydroperoxide. These results suggest that cytosolic glutathione peroxidase and phospholipid hydroperoxide glutathione peroxidase share a role in the reduction of hydroperoxide, but non-Se-dependent glutathione peroxidase (glutathione S-transferase) plays a lesser role.
    Journal of Oral Biosciences 12/2007; 49(4):278-285. DOI:10.2330/joralbiosci.49.278
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    ABSTRACT: An apical-enriched plasma membrane fraction (A-PM) was prepared from rat parotid gland by Mn2+ precipitation. In this fraction, phosphatidylcholine (PC) labelled at the sn-2 position was mainly decomposed into two labelled compounds (free fatty acid and 1,2-diacylglycerol) under Ca2+-free conditions. Studies using double-labelled PC and 2,3-diphosphoglycerate (as a phospholipase D inhibitor) showed that they were produced through different pathways: free fatty acid was released by phospholipase A2 (PLA2) while 1,2-diacylglycerol may be produced by sequential action of phospholipase D and phosphatidate phosphatase. The PLA2 in A-PM did not require Ca2+ for its activity and was highly activated by Triton X-100 and ATP. The inhibitor of the well-documented Ca2+-independent PLA2, bromoenol lactone, did not inhibit the PLA2 activity in A-PM. Although PLA2 activity was detected in other subcellular fractions, the highest specific activity was in A-PM. Its distribution among various fractions was roughly similar to that of the marker enzyme of apical plasma membranes. These findings suggested that Ca2+-independent PLA2 activity is present in apical plasma membranes from rat parotid gland. In addition, to clarify the involvement of the PLA2 in exocytosis, the fusion of exogenous PLA2-treated membranes with secretory granules was examined by fluorescence dequenching assay. This study clearly demonstrated the facilitation of fusion by PLA2 treatment, which suggests some involvement of apical PLA2 in saliva secretion.
    Archives of Oral Biology 10/2001; 46(9):789-99. DOI:10.1016/S0003-9969(01)00050-4 · 1.88 Impact Factor
  • M Mizuno-Kamiya · Y Kameyama · K Yashiro · A Fujita
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    ABSTRACT: We characterized the Ca2+-independent, membrane-associated phospholipase A2 (PLA2) from rat parotid secretory granules. Among four phosphatidylcholine species with different fatty acyl (palmitoyl, oleoyl, linoleoyl, and arachidonoyl) groups at the sn-2 position, 2-arachidonoyl-phosphatidylcholine was the preferred substrate. Such specificity was also apparent even when 2-arachidonoyl-phosphatidylcholine coexisted with another species. The various well-documented inhibitors of PLA2s, bromoenol lactone, arachidonyl trifluoromethyl ketone, methyl arachidonyl fluorophosphate, and diisopropyl fluorophosphate, did not inhibit granular PLA2 activity. The granular PLA2 was activated markedly by ATP, and to a lesser extent by GTP and ATPgammaS. GTP also partially suppressed the ATP-mediated activation. UTP, CTP, GTPgammaS, and the hydrolyzed products of ATP and GTP showed little activation of the enzyme. Neither addition of K-252a nor depletion of Mg2+ affected ATP-mediated activation. Although this enzyme was located in the granular membranes, the granular soluble contents or BSA were required for the full activity and full ATP-mediated activation. These results suggested that the PLA2 located in granular membranes may participate in the liberation of arachidonic acid in parotid cells and be regulated through a mechanism mediated by ATP.
    Journal of Biochemistry 02/1998; 123(2):205-12. DOI:10.1093/oxfordjournals.jbchem.a021923 · 3.07 Impact Factor
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    ABSTRACT: In order to investigate microsomal diacylglycerol acyltransferase activity, ethanol or several detergents have been used as a dispersing agent for water-insoluble substrates. However, ethanol acyltransferase interferes with the activity of this enzyme, and detergents inhibit it. We examined the properties of microsomal diacylglycerol acyltransferase in rat salivary glands without detergents or organic solvents. 1,2-Dioleoyl-sn-glycerol (1,2-diolein) was dispersed by sonication. The activity was measured as the formation rate of [14C]triglyceride using [1-14C]palmitoyl-CoA as an acyl-donor. The reaction was dependent on the microsomal protein and 1,2-diolein at least up to 145 micrograms/ml and 3.6 mM, respectively. The specific activities were 3.91 +/- 0.57 and 3.80 +/- 0.77 nmol/min per mg protein (SEM, n = 4) in the parotid and submandibular glands, respectively. They were 12- to 20-fold higher than the activities in liver, brain and spleen, and two orders of magnitude higher than that assayed with microsomal endogenous diacylglycerol. Adding tissue phospholipids to 1,2-diolein suspension reduced the concentration of 1,2-diolein required for the maximal velocity. A similar, but reduced, effect was induced by egg yolk phosphatidylcholine in place of the tissue phospholipids. The level of activity was recovered by adding another phospholipid class to the phosphatidylcholine. The results suggested that the physical condition of the substrate diacylglycerol affects diacylglycerol acyltransferase activity in rat salivary gland microsomes.
    The International Journal of Biochemistry & Cell Biology 09/1996; 28(8):895-903. DOI:10.1016/1357-2725(96)00026-X · 4.24 Impact Factor
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    ABSTRACT: We investigated the significance of the plasma membrane lipid composition in exocytosis in an in vitro interaction system using an intact secretory granular fraction (SG) isolated from the rat parotid gland. When various liposomes (as a model of plasma membranes) were added to this assay system, rapid and transient amylase release from the SG was evoked and increased by Ca2+ in a concentration-dependent manner. The extent depended upon not only the amount of liposomes but also their lipid composition. The addition of 1,2-diacylglycerol and phosphatidic acid to egg yolk phosphatidylcholine-liposomes remarkably facilitated the release. On the other hand, that of various free fatty acids had different effects depending upon their molecular species. Furthermore, a fluorescence de-quenching study demonstrated that membrane fusion actually occurred in this interaction system, and appeared to correlate with the amylase release. These results suggest that the transient alteration of the membrane lipid composition upon cell activation is a modulator of the exocytotic membrane interaction.
    Journal of Biochemistry 11/1995; 118(4):693-9. · 3.07 Impact Factor
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    ABSTRACT: Microsomal 1-acyl-sn-glycero-3-phosphoinositol (1-acyl-GPI) acyltransferase in the rat submandibular gland showed the highest specific activities for eicosanoid-related polyunsaturated acyl-CoAs, such as arachidonoyl-, bishomo-gamma-linolenoyl- and 5,8,11,14,17-eicosapentaenoyl-CoAs, with low Km values. High activities were also obtained with acyl-CoAs having long (more than 14 carbon atoms) and n - 6 unsaturated (more than 3 double bonds) acyl chains. This enzyme also utilized acyl-CoAs having trans-unsaturated or branched chains, but not short-chains, as substrates, although the activity levels for trans-unsaturated acyl-CoAs were lower than those for cis-unsaturated acyl-CoAs. Chronic administration of isoproterenol induced decreases of this enzyme activity and the content of arachidonic, bishomo-gamma-linolenic and 5,8,11,14,17-eicosapentaenoic acids at the sn-2 position of phosphatidylinositol. These results suggest that enrichment of arachidonic acid in the sn-2 position of phosphatidylinositol is established by the high specificity and affinity of 1-acyl-GPI acyltransferase for arachidonoyl-CoA. On the other hand, the low level of bishomo-gamma-linolenic and 5,8,11,14,17-eicosapentaenoic acids in the sn-2 position of phosphatidylinositol may be explained by their limited availability.
    Biochimica et Biophysica Acta 11/1995; 1258(3):288-96. DOI:10.1016/0005-2760(95)00136-Z · 4.66 Impact Factor
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    ABSTRACT: Chronic (5- and 10-day) administration of isoproterenol, an agent that induces the proliferation of salivary gland cells, produced increases in microsomal 1-acyl-sn-glycero-3-phosphate acyltransferase and 1-acyl-sn-glycero-3-phosphocholine acyltransferase activity in rat parotid glands in parallel with gland enlargement. This increased activity was reduced when the treatment was stopped, the reduction corresponding to the reduction in gland weight. There were significant correlations between lysophospholipid acyltransferase activity and gland weight, and between the activities of the two types of lysophospholipid acyltransferase. However, isoproterenol treatment did not affect any of the steps of the subsequent phospholipid N-methylation. These results suggest that the cell proliferation induced by chronic administration of isoproterenol in the parotid gland is accompanied by reversible and selective increases in microsomal lysophospholipid acyltransferases.
    Journal of Biochemistry 07/1994; 115(6):1040-6. · 3.07 Impact Factor
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    ABSTRACT: A secretory granular fraction (SG) and a plasma membrane rich fraction (PM) have been isolated from rat parotid gland by differential and Percoll gradient centrifugation. With these two fractions, a cell-free interaction system has been reconstituted to clarify the exocytotic interaction between the secretory granules and plasma membranes, and the conditions of amylase release from SG have been characterized in vitro. The addition of PM into this assay system induced a rapid and transient release of amylase from SG. Some other membranes such as erythrocyte ghosts also mimicked the effect of PM. This release was increased by Ca2+, but was not completely blocked by EGTA. Simultaneous addition of 1 mM ATP with 1 mM MgCl2 (Mg-ATP) in the presence of Ca2+ reduced this release. However, in spite of the existence of Mg-ATP, the stimulation of PM-induced amylase release was caused by Ca2+ in a concentration-dependent manner (10(-7)-10(-3) M). These results suggest that Ca2+ and Mg-ATP should participate as important regulators in the exocytotic interaction between secretory granules and plasma membranes in this system. Furthermore, the differences between our system and intact cells are also discussed.
    Biochimica et Biophysica Acta 05/1992; 1116(2):104-11. DOI:10.1016/0304-4165(92)90106-5 · 4.66 Impact Factor
  • X Y Yin · T Koshimizu · Y Yokota · K Shibayama · Y Ohyama · K Yashiro
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    ABSTRACT: Ontogenic expression of somatostatin (SRIF) -messenger RNA (mRNA) in the gastrointestinal tract was examined in neonatal rats aged from 1 day preterm to 60 days postpartum in comparison with that in the hypothalamus. SRIF-mRNA in the hypothalamus was already expressed in prenatal rats and its developmental change was relatively small. In contrast, a unique pattern of SRIF-mRNA expression was seen in the different intestinal regions, gastric antrum, duodenum, jejunum and colon. In the duodenum, SRIF-mRNA level was low at birth, markedly increased during the postnatal 3 days and declined to the previous level by day 21. Jejunal SRIF-mRNA was found in neonates but progressively decreased in a similar way to duodenum. On the contrary, gastric SRIF-mRNA level, which was low during early development, rose rapidly to a peak on day 21 and gradually declined to an adult level. In the colon age-related change was not conspicuous, remaining at a low level. These results indicate that (1) expression of SRIF gene in the intestinal tract is regulated by local factor(s) as well as developmental stage, and (2) shift of SRIF-mRNA pattern occurs during weaning from the duodenum-dominant infantile pattern to the gastric-dominant adult pattern.
    Acta paediatrica Japonica; Overseas edition 03/1992; 34(1):6-11.
  • K Yashiro · S O Shin · Y Sakashita · A Himejima · A Mori · M Yoshida · Y Yokota
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    ABSTRACT: The major constituent free fatty acid in rat parotid and submandibular glands was palmitic acid (about 40% of the total), followed by saturated and unsaturated fatty acids with 18 carbon atoms and arachidonic acid. The composition was changed by chronic administration of isoproterenol, with an increase of linoleic acid and a decrease of arachidonic acid coinciding with changes in the acyl composition of phospholipids. With respect to the metabolism of unsaturated fatty acids, delta 6-desaturation activity converting linoleic acid to gamma-linolenic acid was detected using [14C]linoleoyl-CoA in the submandibular gland. These results suggest that changes in the acyl composition of phospholipids induced by chronic administration of isoproterenol are in part due to changes in free fatty acid composition and that delta 6-desaturation activity may be involved in the regulation of unsaturated fatty acid composition.
    Gifu Shika Gakkai zasshi = The Journal of Gifu Dental Society 01/1991; 17(2):547-56.
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    ABSTRACT: 1. Chronic administration of isoproterenol caused similar alterations of membrane lipid profile in at least two rat parotid subcellular fractions, secretory granular and microsomal. 2. Typical changes in phospholipid classes and fatty-acyl chain groups were an increase of phosphatidylcholine and a decrease of sphingomyelin, and an increase of octadecadienoyl chain and a decrease of eicosatetraenoyl chain, respectively. 3. Electron spin resonance study showed that the isoproterenol-treatment also affected a membrane physical property, which may be through these compositional changes in membrane constituents.
    Comparative biochemistry and physiology. B, Comparative biochemistry 02/1990; 96(1):171-6. DOI:10.1016/0305-0491(90)90358-Z · 2.07 Impact Factor
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    ABSTRACT: Membrane phospholipid compositions of a secretory granule-rich fraction (SG) from rat parotid glands were analyzed and compared with those of a microsomal fraction (Ms) and homogenates. Remarkable differences were concentrated in their phospholipid composition rather than their side-chain composition. SG had significantly higher levels of lysophospholipids (lyso-PL, 8.3 %) and phosphatidylethanolamine (PE, 30.5 %), whereas it had lower levels of phosphatidylcholine (PC. 40.3%) and phosphatidylserine (PS, 2.4%) than those of Ms. Although these phospholipids showed a characteristic side-chain composition depending on each phospholipid class, few differences among the three fractions were found in individual phospholipid side-chain compositions. Only PE from SG was relatively poor in the alkenyl chain, especially the octadec-1'-enyl chain, and concomitantly rich in octadecanoyl chain compared with PE from Ms. The side-chain compositions of total phospholipids from SG, Ms and homogenates were nearly similar to one another. Furthermore, ESR analysis demonstrated that fluidity of hydrophilic region of liposomes prepared by the phospholipids which were extracted from individual fractions, increase in the order of Ms<homogenates<SG. On the contrary, there were no differences in the fluidity of their hydrophobic regions.These results suggest that the granular membranes have a characteristic phospholipid profile, which affects the physical property of granular membranes.
    Shika Kiso Igakkai zasshi = Japanese journal of oral biology 01/1990; 32(5):563-573. DOI:10.2330/joralbiosci1965.32.563
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    ABSTRACT: Rat submandibular gland phosphatidylcholine mainly consisted of the 1-saturated acyl-2-unsaturated acyl type. The high occupancy of unsaturated fatty acid at the C-2 position is in part explained by the preference of microsomal acyl-CoA:1-acyl-sn-glycero-3-phosphocholine (1-acyl-GPC) acyltransferase for unsaturated fatty acyl-CoAs. This enzyme activity was partially inhibited by divalent cations. Ca2+ may be important for regulation of a deacylation-reacylation cycle, suggested because Ca2+ is also known to activate the deacylation enzyme, phospholipase A2. Although the presence of 1-acyl-GPC acyltransferase activity is also observed in plasma membrane of the submandibular gland, the microsomal enzyme showed properties different from the enzyme in plasma membrane in terms of its susceptibility to neural salts and detergents. Cell proliferation caused by chronic administration of isoproterenol resulted in an increase of linoleic acid at the C-2 position of phosphatidylcholine. However, this alteration did not correlate with the changes of activity and substrate specificity of 1-acyl-GPC acyltransferase and the other C-2 acylation enzyme, 1-acyl-sn-glycero-3-phosphate acyltransferase, which suggests that the alteration of fatty acid by isoproterenol treatment is due to a change of supply of substrates or specific acyl breakdown of phosphatidylcholine.
    Biochimica et Biophysica Acta 10/1989; 1005(1):56-64. DOI:10.1016/0005-2760(89)90031-3 · 4.66 Impact Factor
  • K Yashiro · Y Kameyama · M Mizuno · A Okada · Y Yokota
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    ABSTRACT: Successive phospholipid N-methylation from phosphatidylcholine to phosphatidylethanolamine in submandibular gland and liver microsomes proceeded without the addition of exogenous phospholipid substrate. Methylation activity in the submandibular microsomes showed different susceptibilities to various detergents than the liver enzyme and also partially required Mg2+. However, the three methylation steps could not be distinguished by their Mg2+ requirements. Ca2+ had no effect on the activity. The methylation activity in submandibular gland was much lower than in liver. Chronic administration of isoproterenol, which causes an increase of phosphatidylcholine in membrane phospholipids of salivary glands, decreased methylation activity in the submandibular gland. Thus the increase in phosphatidylcholine in isoproterenol-treated rat salivary glands may not be derived from the phospholipid methylation pathway, but may be due to stimulation of other routes of phosphatidylcholine metabolism.
    Archives of Oral Biology 02/1989; 34(3):203-8. DOI:10.1016/0003-9969(89)90009-5 · 1.88 Impact Factor
  • K Yashiro · Y Kameyama · M Mizuno · Y Yokota
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    ABSTRACT: 1. In rat parotid gland, chronic administration of isoproterenol caused significant increase of linoleic acid and decrease of arachidonic acid at the sn-2 position of phosphatidylcholine. 2. The activities of 1-acyl-sn-glycero-3-phosphate and 1-acyl-sn-glycero-3-phosphocholine acyltransferases were increased 3-8-fold and 2-fold, respectively, in the parotid gland microsomes of isoproterenol-treated rat. 3. Furthermore, the specificity of these two enzymes for various acyl-CoAs was also changed by administration of isoproterenol. 4. The alteration of unsaturated fatty acid composition at the sn-2 position of phosphatidylcholine was at least in part due to the change of activity and substrate specificity of lysophospholipid acyltransferases.
    Comparative Biochemistry and Physiology Part C Comparative Pharmacology and Toxicology 02/1988; 90(2):397-402.
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    ABSTRACT: 1. 1-Acyl-sn-glycerol-3-phosphorylcholine and 1-acyl-sn-glycerol-3-phosphate acyltransferase activities were characterized in rat salivary gland microsomes. 2. The acyl-CoA selectivities between these two kinds of lysophospholipid acyltransferase activities were very different. 3. When the three major glands were compared (parotid, submandibular, sublingual), they showed their own particular acyltransferase activity, but they had very similar in acyl-CoA selectivity. 4. Those observations were also compared in rat liver microsomes.
    Comparative biochemistry and physiology. B, Comparative biochemistry 02/1988; 90(2):269-73. DOI:10.1016/0305-0491(88)90071-5 · 2.07 Impact Factor
  • Shika Kiso Igakkai zasshi = Japanese journal of oral biology 01/1988; 30(6):841-847. DOI:10.2330/joralbiosci1965.30.841
  • Shika Kiso Igakkai zasshi = Japanese journal of oral biology 01/1988; 30(2):234-238. DOI:10.2330/joralbiosci1965.30.234
  • M Mizuno · Y Kameyama · K Yashiro · Y Yokota
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    ABSTRACT: A secretory granular fraction isolated from rat parotid glands was remarkably different from a microsomal fraction in its phospholipid composition. It had higher levels of lysophospholipids (8%) and phosphatidylethanolamine (31%), while there were lower levels of phosphatidylcholine (40%) and phosphatidylserine (2.1%) than the microsomal fraction. However, fatty acid compositions of individual phospholipid classes from the two subfractions were found to be nearly similar to each other. ESR analysis demonstrated that extracted phospholipids from the secretory granular fraction were more fluid than those from microsomes. The relevance of these observations to physiological function of secretory granules is discussed.
    Cell Biology International Reports 10/1987; 11(9):629-36. DOI:10.1016/0309-1651(87)90096-8