Histamine downregulates CD14 expression via H2 receptors on human monocytes

Lipopolysaccharide (LPS) binds to LPS-binding protein (LBP) in plasma and is delivered to the cell surface receptor CD14 on human monocyte. LPS is transferred to the transmembrane signaling receptor toll-like receptor (TLR) 4. In the present study, the effect of histamine on the expression of CD14 on human monocytes was investigated. Histamine concentration- and time-dependently decreased the expression of cell surface CD14, whereas histamine did not decrease mRNA for CD14 nor increase soluble CD14 (sCD14). The inhibitory effects of histamine on CD14 expression were antagonized by H2-receptor antagonist, but not by H1 and H3/H4 antagonist. The effects of selective H2-receptor agonists, 4-methylhistamine and dimaprit, on CD14 expression mimicked that of histamine indicating that histamine regulated CD14 expression through the stimulation of H2-receptors. The pretreatment with histamine partially inhibited the LPS-induced TNF-alpha production in human peripheral blood mononuclear cells (PBMC). Such inhibition might be due to the down-regulation of CD14 expression on monocytes by histamine.     

Characterization and expression of cDNA encoding coproporphyrinogen oxidase from a patient with hereditary coproporphyria

Hereditary coproporphyria (HCP) is an acute hepatic porphyriawith autosomal dominant inheritance, but with a variable degreeof clinical expression. Molecular cloning, sequencing and expressionof the defective gene for coproporphyrinogen oxidase (CPO) ina patient with HCP were carried out. Enzyme assays revealedthat CPO activity in EBV-transformed lymphoblastoid cells fromthe proband and one of her sisters was     

Role of microfilaments in the exocytosis of rat peritoneal mast cells

When rat peritoneal mast cells were treated with the potent histamine releaser compound 48/80 in the presence of tetramethylrhodamine-labeled G-actin, the fluorescent G-actin particles were bound to the surface of extruded granules and to the cell surface. When rhodamine-phalloidin was incorporated into permeabilized rat mast cells in a Ca2+-free medium, rhodamine fluorescence was observed on the cell surface accompanied by serpentine ridges which appeared in the resting state. After perfusion with a cytosol-like solution containing Ca2+, rhodamine fluorescence appeared on the cell surface as a distinct network formation. In some cases, circular fluorescences which appeared to surround the extruded pores were observed in the cell membrane. These findings indicate the existence of actin filaments in the cell membrane and/or subplasmalemmal network. In whole-mount preparations, the granules were surrounded very densely with microfilaments of various widths. After exposure to compound 48/80, granules protruding through the cell membrane were wrapped in many filaments. The extruded granules located in the periphery of the cells were connected by many filamentous structures and disruptions in the middle of these connections were occasionally observed. In some cases, circular configurations of microfilaments were observed at the bottom of the extruded granules and in others dense gatherings of microfilaments were seen just beneath the granules, as if the latter were being pushed up and out of the cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunoelectron microscopic study on the cross-reactivity of antibodies to adult T-cell leukemia-associated antigens in human and monkey sera

The cross-reactivity of antibodies to adult T-cell leukemia (ATL)-associated antigens (ATLA) in human and monkey sera was investigated by indirect immunoperoxidase and immunoferritin methods using a human cell line (MT-2) carrying a type C virus (HTLV), two monkey cell lines (Si-1 and Si-3) carrying HTLV, and a monkey cell line (Si-2) carrying a type C virus isolated from an anti-ATLA-positive monkey. Anti-ATLA-positive but not-negative human and monkey sera gave positive immunoperoxidase reaction with all four virus-positive cell lines when studied by light microscopy. Electron microscopic findings revealed ferritin or peroxidase labeling of virus particles and plasma membranes of these four cell lines with antibody-positive but not-negative human and monkey sera. These results clearly indicate the cross-reactivity of anti-ATLA antibodies in human and monkey sera at light and electron microscopic levels, and the presence of antigenic determinants common to the surface of type C virus particles of human and monkey origin.     

Protective role of heme oxygenase-1 in renal ischemia

Oxidative stress, which has been implicated in the pathogenesis of ischemic renal injury, degrades heme proteins, such as cytochrome P450, and causes the elevation in the level of cellular free heme, which can catalyze the formation of reactive oxygen species. Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is induced not only by its substrate, heme, but also by oxidative stress. In various models of oxidative tissue injuries, the induction of HO-1 confers protection on tissues from further damages by removing the prooxidant heme, or by virtue of the antioxidative, antiinflammatory, and/or antiapoptotic actions of one or more of the three products, i.e., carbon monoxide, biliverdin IXalpha, and iron by HO reaction. In contrast, the abrogation of HO-1 induction, or chemical inhibition of HO activity, abolishes its beneficial effect on the protection of tissues from oxidative damages. In this article, we review the protective role of HO-1 in renal ischemic injury, and its potential therapeutic applications. In addition, we summarize recent findings in the regulatory mechanism of ho-1 gene expression.     

Synthesis of optically active polymers by asymmetric catalysts. IV. Dialkylzinc – alcohol system as catalyst for asymmetric-selective polymerization of propylene oxide

The system diethylzinc/optically active alcohol was examined as catalyst for asymmetric-selective polymerization of propylene oxide. Optically active alcohols with rigid structure are effective for the asymmetric selection. D (–)-1-Methoxypropanol-2 as well as poly(D -propylene oxide) of low molecular weight with hydroxyl end groups select L (–)-propylene oxide. ?Catalyst control”? mechanism of the stereoselection in the polymerization is suggested on this and other bases.     

Stereoregulating behaviour of organoalkali and organoalkaline earth compounds in polymerization of methyl methacrylate

Stereoregulating behaviour of organoalkali and organoalkaline earth metal compounds in methyl methacrylate (MMA) polymerization has been studied. Low temperature and polar solvents such as tetrahydrofuran (THF) favour formation of syndiotactic polymer when lithium and magnesium ketyls are used as catalysts. Whereas isotactic polymer is obtained with sodium ketyl even in THF at ?70°C. Lithium aluminum hydride (LiAlH₄) gave almost complete isotactic polymer in high conversion in diethyl ether or toluene even at low temperature, and lithium aluminum tetraethyl (LiAlEt₄), on the other hand, gave very highly syndiotactic polymer under the same conditions. The solvent, besides, showed very important role in stereoregulation, that is, LiAlH₄ could give syndiotactic polymer in a polar solvent at low temperature. Polymer structure was analyzed by NMR- and IR-spectroscopy. The electrical conductivities of these catalyst systems were measured and there was found a parallelism between those values and stereoregularities of polymers obtained by the respective catalyst systems.     

Correlation between the number of apoptotic cells and expression of the apoptosis-related antigens Fas, Ley and bcl-2 protein in non-Hodgkin's lymphomas

The relationship between the number of apoptotic cells and the expression of apoptosis-related antigens was examined In 56 cases of non-Hodgkin's lymphomas and in 10 cases of reactive hyperplastic lymph nodes (RHL). Apoptosis was visually quantified by the in situ end-labeling (ISEL) method, and the expression of Fas, Le^y antigens and bcl-2 protein was examined by Immunohistochemistry. The expression of Le^y antigen was observed in germinal centers of RHL and 45% of non-Hodgkin's lymphomas. The apoptotic cell count (AC) in follicular lymphomas was significantly less than that in diffuse lymphomas. The distribution pattern of apoptotic cells In follicular lymphomas was inverse to that in RHL. In follicular lymphomas, AC was lower in follicles than in inter-follicular areas. In contrast, AC was higher in follicles than in Interfollicular areas in RHL. Le^y antigen-positive lymphomas showed a significantly higher AC than the negative cases. The Fas antigen-positive lymphomas showed a higher AC than the negative cases. However, AC in bcl-2 protein-positive and negative cases was not significantly different. These results suggest that Le^y and Fas antigens appear to be involved in the apoptotic tendency of tumor cells in non-Hodgkin's lymphomas, whereas bcl-2 does not necessarily.