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Biomedical subjects

N Orsi

Publications and source records attributed to N Orsi.

At least 91 records · Page 5Linked to original sources
PubMed1986

Role of sialic acid in cell receptors for vesicular stomatitis virus.

The role of sialic acid in the receptors for vesicular stomatitis virus (VSV) was investigated by treating chick embryo related (CER) cells and goose erythrocytes with neuraminidases from different sources and studying the effects produced on both infection and haemagglutination. The virus attachment to CER cells was reduced by their treatment with C. perfringens and A. ureafaciens neuraminidases and the susceptibility to viral infection of desialylated CER cells was recovered by coating with gangliosides immediately after enzymatic treatment. By contrast, enzymatic treatment of goose erythrocytes enhanced their agglutinability by VSV. The experiments carried out to test the ability of sialoglycolipids (gangliosides) and asialoglycolipids (cerebrosides) to inhibit virus attachment to CER cells or to goose erythrocytes showed that only gangliosides were able to inhibit VSV infection and haemagglutination.

Animals↗
PubMed1986

Study of receptors for vesicular stomatitis virus in vertebrate and invertebrate cells.

Early interactions between vesicular stomatitis virus (VSV) and susceptible cells were examined in cell lines of mammalian (HeLa), bird (CER), piscine (EPC) and arthropod (Aedes albopictus) origin showing different permissiveness to VSV growth. The chemical nature of receptors was investigated either by modification of cell surfaces with different enzymes or by competition for VSV binding between extracted membrane components and whole cells. Results obtained indicate that in all cell models, membrane lipid components show receptor activity whereas glycid groups participate to the in virus binding to a different extent.

Aedes↗
PubMed1986

Effect of concanavalin A on early interactions of Sindbis virus with goose erythrocytes and BHK 21 cells.

The role of mannose containing molecules in Sindbis virus envelope glycoproteins and cell membrane receptors was investigated by means of concanavalin A (con A). Treatment of virus or BHK 21 cells with the lectin before infection reduced viral infectivity. Hemagglutination and hemolysis showed a different sensitivity to con A. Hemagglutination was not affected by the lectin and treatment of erythrocytes with con A produced an enhancement of agglutinability by the virus. Hemolytic activity was, on the contrary, strongly reduced by the lectin. The inhibition observed is due to an action on viral structures and not to an interaction with erythrocyte receptors because con A did not affect the hemolysis when preincubated with erythrocytes.

Animals↗
PubMed1985

Antifungal activity of ovotransferrin towards genus Candida.

The inhibiting activity of ovotransferrin was tested towards different species belonging to genus Candida. Of one hundred strains tested, only C. krusei showed a noticeable resistance, while the other species appeared to be more sensitive than bacteria to the action of ovotransferrin. The influence of anions, such as bicarbonate and citrate, on the inhibiting activity of ovotransferrin was also investigated. Moreover it was observed that iron saturated ovotransferrin retained its activity, thus suggesting an interaction between the protein and Candida cells.

Antifungal Agents↗
PubMed1985

E. coli adherence to CER cells infected by vesicular stomatitis virus.

Research was carried out on the adherence of a mannose-resistant uropathogenic E. coli strain to CER cells infected with vesicular stomatitis virus (vsv). A decrease in the bacterial adhesion was noticed during the early phases of viral infection, probably due to a close relationship between cell receptors for VSV and E. coli, both containing glycolipids and phospholipids. In a later phase of viral infection, on the contrary, corresponding to the appearance on the cell surface of newly synthesized viral antigens, bacterial adherence was enhanced. This last observation suggested a possible predisposition of the host to bacterial colonization during renal viral infection.

Adhesiveness↗
PubMed1985

Gangliosides in early interactions between vesicular stomatitis virus and CER cells.

In the present report an attempt was made to elucidate the role of gangliosides in early interactions between vesicular stomatitis virus (VSV) and CER cells. Research was carried out to test the ability of gangliosides from mammal brains and from CER cells to inhibit viral attachment to susceptible cells. The incubation of VSV in the presence of gangliosides decreased the subsequent infection of CER cells by the virus. When similar experiments were performed with gangliosides inserted in liposomes the inhibition of infection was enhanced. Since carbohydrate moieties could participate to rhabdovirus binding as a part of a glycolipid receptor, CER cells were subjected to the action of glycosidases and these produced a fall in the viral attachment. Deglycosilated CER cells reacquired their susceptibility to virus infection after coating with gangliosides immediately after enzyme treatment. Results obtained show the participation of gangliosides in the receptorial structure for vesiculovirus of susceptible CER cells.

Animals↗
PubMed1985

Effect of amantadine on rhabdovirus infection.

Enveloped viruses enter host cells by fusion or viropexis. The latter mechanism is the prevalent entry pathway of rhabdoviruses into susceptible cells. Amantadine, a lysosomotropic agent, inhibits the multiplication of various groups of viruses. The effect of this drug was investigated on vesicular stomatitis virus and rabies fixed virus strain replication in fibroblasts. Amantadine was added to cells before, during and after infection to detect the phase of viral replication affected by the drug. Cells were inoculated with viruses at 4 degrees C and the incubation temperature was progressively raised to 37 degrees C in order to observe the effect of amantadine on attachment and early stages of viral replication. Experimental results indicated that the compound inhibited rhabdovirus infection in CER cells. Viral attachment and penetration did not appear to be affected by the drug, while later steps were inhibited, probably at the level of uncoating when the virus is released from the lysosomes into the intracytoplasmic compartment.

Amantadine↗
PubMed1984

Role of phospholipids in rhabdovirus attachment to CER cells. Brief report.

The effect of phospholipases on rhabdovirus attachment to CER cells and the competitive binding of phospholipids and viruses to cells were studied. Results obtained indicate that, although to a different extent, some phospholipids represent a binding site for both Vesicular Stomatitis Virus (VSV) and rabies virus.

Animals↗
PubMed1984

Group B streptococci: extracellular neuraminidase production and virulence in mouse.

Neuraminidase production by reference strains of various group B streptococci serotypes was investigated before and after serial passages in mouse. The enzyme production was tested in culture filtrates using bovine submaxillary mucin as substrate. Although passages in mouse markedly increased the virulence of all the strains it was not possible to demonstrate a relationship between the increased virulence and the enzyme production.

Animals↗
PubMed1983

A study on the erythrocyte structures involved in the interaction with mannose-resistant E. coli adhesins.

Research has been carried out on the role of different chemical groups present on human group A erythrocyte membranes and involved in the interaction with mannose-resistant (MR) adhesins of a uropathogenic E. coli strain. For this purpose several enzymes specifically acting on protein, lipid and carbohydrate components have been used to modify the erythrocyte surface structures and the effect produced by these treatments on the agglutinability of red blood cells by E. coli has been studied. Moreover different biological compounds have been tested as possible competitive inhibitors for erythrocyte receptors involved in MR agglutination by E. coli.

Adhesins, Escherichia coli↗
PubMed1983

Activity of human serum lipoproteins on the infectivity of rhabdoviruses.

The inhibiting activity of various human serum lipoprotein classes and their lipid components on the infectivity of rhabdoviruses has been studied. The research has been carried out according to different experimental procedures on both the vesicular stomatitis virus (Indiana strain), and the fixed rabies virus (CVS strain). The results obtained have shown an inhibition of the infectivity of VSV and CVS, mainly linked to the very low and low density lipoprotein classes. It has also been demonstrated that the inhibitors act directly on viruses causing a decrease in their attachment to host cells.

Humans↗
PubMed1983

Studies of the antimicrobial activity of ovotransferrin.

The antibacterial activity of ovotransferrin (conalbumin) against different bacterial species was studied in vitro. The most sensitive species were Pseudomonas sp., E. coli, S. mutans; and the most resistant ones S. aureus, Proteus sp., Klebsiella. The bacteriostatic activity of conalbumin in various conditions was also tested. The presence of bicarbonate ions always increased the activity of conalbumin, while an antagonistic effect of citrate was observed in bacteria with a receptor for the iron-citrate complex. Experiments with conalbumin covalently linked to Sepharose 4B indicated that its antibacterial activity may not be due simply to the removal of iron from the medium, but probably involves other metals and an interaction with the bacterial surface. The in vitro studies carried out with conalbumin and lactoferrin demonstrated that the two proteins produced a similar inhibition of growth of E. coli and S. mutans. The in vivo studies showed that the protective effect of conalbumin in newborn guinea pigs with E. coli by gastrointestinal route was similar to that naturally provided by the lactoferrin present in milk.

Animals↗
PubMed1982

Antibacterial activity of matrix-bound ovotransferrin.

Ovotransferrin immobilized by covalent linkage to Sepharose 4B showed a bacteriostatic effect towards Escherichia coli similar to that of free ovotransferrin. The growth of the bacteria, after exposure to the gel-bound ovotransferrin and its removal, depended on the length of exposure. The results suggest that the antibacterial activity of transferrin is not due simply to the removal of iron from the medium.

Anti-Bacterial Agents↗
PubMed1982

Role of carbohydrates in cell membrane receptors for vesicular stomatitis virus.

A study has been made to clarify the importance of some carbohydrate components of goose red blood cell and BHK 21 cell membrane receptors for vesicular stomatitis virus (VSV). Experiments have been carried out by inducing enzymatic modifications on the surface of intact cells and following the interaction between VSV and treated cells. Results obtained indicate that the removal of mannose, galactose and fucose from cell membranes reduces the attachment of the virus to cell receptors.

Animals↗
PubMed1981

Receptors for BK virus on human erythrocytes.

The chemical nature of BK virus receptors on human erythrocytes was investigated. Glycosidases, KIO4, proteases, phospholipases and other substances acting specifically on different structures of plasma membranes were used to ascertain the role of surface cell components in the interaction with BK virus. The results obtained indicate an analogy between BK virus receptors on red cells and non-antibody serum inhibitors active against haemagglutination by the same virus.

BK Virus↗
PubMed1981

Resistance of genus Proteus to ovotransferrin.

A total of 100 strains of Proteus, clinically isolated, were tested for sensitivity to ovotransferrin and CrCl3. Only a minority of the tested strains were not capable of growing in the presence of these iron chelating substances. Significant differences in the resistance among the four species of Proteus were noticeable only by addition to the culture medium of CrCl3 5 mM. The fact that sensitive strains were capable of growing after addition of citrate to culture medium containing ovotransferrin or CrCl3 suggests the presence in the genus Proteus of a citrate-dependent iron transport system.

Chlorides↗