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Biomedical subjects

N Orsi

Publications and source records attributed to N Orsi.

At least 73 records · Page 4Linked to original sources
PubMed1989

Involvement of carbohydrates in vesicular stomatitis virus-cell early interaction.

The role of N-acetylneuraminic acid and N-acetyl-D-glucosamine containing molecules in vesicular stomatitis virus-cell interaction was studied using specific lectins (limulin and wheat germ agglutinin) and esoglycosidases (neuraminidase, beta-galactosidase, alpha-mannosidase, alpha-fucosidase, beta-N-acetyl-D-glucosaminidase). Lectin treatment of vesicular stomatitis virus (VSV) indicated that carbohydrates of the VSV G envelope glycoprotein were not required for virus infectivity, whereas sialic acid appeared directly involved in the attachment of virus to erythrocytes. The comparative results obtained after enzymatic digestion of cell membrane carbohydrates or their cross linking by lectins demonstrated that whereas VSV infectivity was strongly reduced by pretreatment of chick embryo cells, virus binding to erythrocytes was unaffected by such treatments. We conclude that sugar residues may participate at the host cell attachment site which differs, at least in part, from the membrane binding site of erythrocytes.

Acetylglucosamine↗
PubMed1989

Involvement of lipids in the interaction of Sindbis virus with goose erythrocytes.

The chemical nature of Sindbis virus receptors on goose erythrocytes was investigated by means of two different experimental approaches: by testing the capacity of human serum lipoproteins (HDL, LDL, VLDL) to compete with erythrocytes for virus binding and by enzymatic and chemical modifications of the cell membrane. Each class of lipoproteins was separated into its protein and lipid components which were tested for hemagglutination and hemolysis inhibiting activity. Only the lipid moieties were able to inhibit binding and fusion activities of the virus. Enzymatic treatments of the erythrocyte surface showed that sialic acid and trypsin-sensitive proteins were not involved in Sindbis virus membrane receptor and that some phospholipids probably represent important components of the cellular binding site.

Animals↗
PubMed1988

Characterization of rat brain cellular membrane components acting as receptors for vesicular stomatitis virus. Brief report.

The chemical nature of the binding sites for vesicular stomatitis virus (VSV) was studied by measuring the ability of solubilized rat brain cell membranes (SRBM) to compete with cultured cells for viral binding. SRBM significantly reduced both binding and infectivity of VSV. After separation of protein and lipid components from membranes, VSV infection was unaffected by the protein fraction, whereas the lipid moiety, specifically phospholipids and glycolipids, showed a dose-dependent inhibitory effect. The essential role of phospholipid and sialic acid-containing glycolipid molecules as receptors for VSV was also suggested by the sensitivity of the inhibitory activity of SRBM and lipid components to phospholipase C and neuraminidase digestion.

Animals↗
PubMed1988

Identification of lipid components of human serum lipoproteins involved in the inhibition of Sindbis virus infectivity, hemagglutination, and hemolysis.

Human serum high density lipoproteins (HDL), low density lipoproteins (LDL) and very low density lipoproteins (VLDL) were isolated and tested for their ability to inhibit Sindbis virus infectivity, hemagglutination and hemolysis. VLDL and LDL produced a strong reduction on both viral infectivity on Vero cell monolayers and attachment and fusion with erythrocytes, whereas HDL appeared to be only a weak inhibitor. Lipid and protein components were extracted from each class of lipoproteins to identify the molecules responsible for the inhibiting activity. Only the lipid moiety was found to inhibit Sindbis virus biological activities. Among the individual lipid components of lipoproteins, neutral lipids (cholesterol, oleic acid and palmitic acid) and negatively charged phospholipids (phosphatidylserine and phosphatidylinositol) and glycolipids (GM 3 ganglioside and cerebroside sulphate) were able to neutralize the virus suggesting that either hydrophobic or electrostatic interactions are involved in the inhibition.

Apoproteins↗
PubMed1988

Inhibition of rabies virus infection by a soluble membrane fraction from the rat central nervous system.

This paper describes the inhibitory effect of a normal rat brain solubilized membrane preparation (RBSM-liposomes) on rabies virus infection. Rabies virus was incubated with RBSM-liposomes or their separated components (proteins, phospholipids, gangliosides) before infection of CER or neuroblastoma cells. In addition, both RBSM-liposomes and target cells were treated with enzymes prior to the infection step. All these experimental procedures showed that the active components were mainly lipids.

Animals↗
PubMed1988

Effect of isoflavans and isoflavenes on rhinovirus 1B and its replication in HeLa cells.

The effect of newly synthesized halogenated isoflavans and isoflavenes on human rhinovirus 1B (HRV 1B) infection of HeLa cells has been examined. Both series of drugs inhibited virus plaque formation in cell cultures, isoflavans being more effective than isoflavenes. Cells pretreated with compounds before challenge with HRV 1B became resistant to the virus-induced cytopathic effect. The antiviral state induced by the most active compounds persisted for at least 10 h and did not appear to be mediated by interferon production. Experiments whereby the compounds were added at varying times indicated that the isoflavans and isoflavenes interfere with early events of virus replication without affecting virus binding to the cell membrane. In addition to their effects on virus multiplication, the isoflavans were also found to have a direct action on the virus. The inhibitory effect on virus infectivity required extraction with chloroform for reversal. Isoflavans also protected the virions against mild acid or heat inactivation.

Cell Survival↗
PubMed1988

Effect of cellular inhibitors on the infection of various susceptible cells with vesicular stomatitis virus.

The effect of some cellular function inhibitors on adsorption and successive events of penetration of vesicular stomatitis virus to phylogenetically unrelated permissive cells was investigated. Treatment of HeLa, CER, EPC and Aedes albopictus cells with colcemide and cytochalasin D which affect cytoskeleton organization indicated that microfilaments but not microtubules were involved in the early events of VSV infection. Inhibitors of oxidative phosphorylation such as dinitrophenol and sodium azide, and the glycolysis inhibitor 2-deoxy-D-glucose, did not allow multiplication of prebound virions, demonstrating that VSV replication is largely energy dependent in either host cells examined.

Adsorption↗
PubMed1988

Enhanced antimicrobial activity of lactoferrin by binding to the bacterial surface.

In order to elucidate the mechanisms involved in the antibacterial activity of lactoferrin, quantitative determinations of siderophore production and lactoferrin adsorption on various bacterial species were performed. The binding of lactoferrin took place both on Gram-positive and Gram-negative species and occurred with bacterial cells grown in stress or in excess of iron. The different degrees of sensitivity to lactoferrin observed could not be directly related to the type and amount of siderophores produced. However, it was possible to find a correlation between the capacity of some strains to bind lactoferrin and their sensitivity to this protein. These data suggest that the binding of lactoferrin on the cell surface can result in an antibacterial activity additional to iron witholding.

Adsorption↗
PubMed1987

Study of the chemical nature of Frp/3 cell recognition units for hepatitis A virus.

Research has been carried out in order to clarify the chemical nature of cell receptors interacting with a fast growing strain of hepatitis A virus (HAV) producing a cytopathic effect on Frp/3 cells. Cell surface susceptibility to HAV attachment has been studied after treatment with enzymes acting on different chemical groupings. Results obtained showed a lowering of cell susceptibility to HAV infection following the action of phospholipase A2, phospholipase C, trypsin and beta-galactosidase. These data suggested that phospholipids, proteins and galactose participate to the cellular receptorial area for HAV.

Cell Line↗
PubMed1987

The effect of saturation with Zn2+ and other metal ions on the antibacterial activity of ovotransferrin.

The antibacterial activity of metal complexes of ovotransferrin was tested "in vitro" against different bacterial species and the Zn2+ saturated ovotransferrin appeared to be the most active by comparison with the apo-protein and other metal complexes. Appropriate controls showed that such an effect was neither due to Zn2+ ions, nor to iron deprivation, but to a specific activity of the Zn-ovotransferrin complex. This antibacterial activity required a direct contact of Zn-ovotransferrin with the bacterial surface. In vivo experiments confirmed the higher antibacterial activity of Zn-ovotransferrin as compared with the apo-form.

Animals↗
PubMed1987

VSV binding to lipids from different cell lines. Brief report.

Gangliosides from different cells were tested for their inhibiting activity on VSV attachment to CER cells and goose erythrocytes. This inhibiting activity was enhanced when gangliosides were inserted into liposomes, in particular if containing phosphatidylserine.

Animals↗
PubMed1987

The effect of lipophilic amines on the growth of hepatitis A virus in Frp/3 cells.

The effect of lipophilic amines on hepatitis A virus infection in a monkey cell line (Frp/3 cells) was studied. Ammonium chloride, amantadine, methylamine and dansylcadaverine inhibited viral antigen synthesis when added to the cells at least one hour after the attachment step. Results obtained suggest that the HAV entry pathway in Frp/3 cells follows an endocytic route and that viral uncoating takes probably place in endosomes and/or lysosomes.

Amantadine↗
PubMed1987

Entry pathway of vesicular stomatitis virus into different host cells.

A biochemical and morphological investigation of the mechanism of entry of vesicular stomatitis virus (VSV) into host cells of mammalian (HeLa), avian (CER), piscine (EPC) and arthropod (Aedes albopictus) origin, is described. VSV was capable of infecting all cell lines tested by a endosome- and/or a lysosome-dependent step since ammonium chloride and amantadine blocked the early stages of infection. Complement-dependent immune lysis of infected host cells provided evidence that in none of the four different cell types examined did insertion of VSV antigens occur from the outside to any great extent on the cell surface. When the entry process was studied by electron microscopy, virus particles were seen to be bound to the cell surface at 0 degrees C. After warming at 37 degrees C for homeothermic cells or at 26 degrees C for poikilothermic cells, virus was detected within coated pits and coated vesicles and, later, in lysosomes. VSV entry was seen to take place by endocytosis in all four cell lines, which were derived from phylogenetically unrelated species.

Aedes↗
PubMed1987

Inhibition of BK virus haemagglutination by gangliosides.

The effect of gangliosides extracted from human group O Rh+ erythrocytes on haemagglutination by BK virus was investigated. Experiments were performed on both ganglioside mixtures and isolated fractions separated by column chromatography and characterized by thin-layer chromatography. These results were compared with those obtained with standard preparations of gangliosides, and the inhibiting activity was shown to be confined mainly to gangliosides with a RF lower than GM1. It was also observed that the insertion of gangliosides in liposomes increased the haemagglutination-inhibiting activity and that ganglioside coating restored the ability of glycosidase-treated human red blood cells to agglutinate.

BK Virus↗
PubMed1987

Characterization of membrane components of the erythrocyte involved in vesicular stomatitis virus attachment and fusion at acidic pH.

Goose erythrocyte membranes were isolated and tested for their ability to compete with red cell receptors for vesicular stomatitis virus (VSV) attachment and fusion at acidic pH. Crude membranes, solubilized with Triton X-100, Tween 80 and octyl-beta-D-glucopyranoside, showed a dose-dependent inhibitory effect on virus binding and haemolysis. The chemical nature of the active molecules was investigated by enzyme digestion and by separation of purified components. Only the lipid moiety, specifically phospholipid and glycolipid, was found to inhibit VSV attachment; a more detailed analysis of these molecules showed that phosphatidylinositol, phosphatidylserine and GM3 ganglioside were responsible for the inhibitory activity and could therefore represent VSV binding sites on goose erythrocyte membranes. Removal of negatively charged groups from these molecules by enzymic treatment significantly reduced their activity, suggesting that electrostatic interactions play an important role in the binding of VSV to the cell surface. Enzymic digestion of whole erythrocytes confirmed the involvement of membrane lipid molecules in the cell surface receptor for VSV.

Animals↗
PubMed1987

Adhesive properties of Pseudomonas aeruginosa isolated from urinary tract infections.

A research was carried out on the adhesive properties of 104 uropathogenic strains of P. aeruginosa. On the basis of the adhesiveness to various types of cell it was possible to identify the most frequent adhesive patterns. Moreover, the ability of some carbohydrates to inhibit the adhesiveness of P. aeruginosa and the effect of some enzymes on the agglutinability of human erythrocytes by non-hemagglutinating bacterial strains was studied.

Agglutination Tests↗
PubMed1987

In vitro inhibition of Trichomonas vaginalis growth by some ortho-phenacyloxy-benzyl alcohols and their derivatives.

Some phenacyl ethers of different ortho-hydroxy-benzyl alcohols and analogues have been synthesized and tested for the in vitro activity towards Trichomonas vaginalis. The most active compounds had a minimum inhibitory concentration of 6.25 micrograms/ml and appeared to be of a certain interest as representative of a new type of anti-Trichomonas substances not containing a nitro group.

Acetophenones↗