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S Paglini

Publications and source records attributed to S Paglini.

14 recordsLinked to original sources
PubMed2005

Cellular receptor for Pixuna virus in chicken embryonic fibroblasts.

In this study, we describe the isolation and partial characterization of a Pixuna virus receptor, which is a component of a plasma membrane fraction of chicken embryo fibroblast (CEF). Polyclonal antiserum was prepared from rabbits immunized with the membrane fraction. Said polyclonal antiserum reacted in a similar way as monoclonal antibodies raised against the membrane fraction. Both antisera were able to prevent CEF and Vero cells from infection with Pixuna virus. Immunofluorescence studies suggested that the receptors found in the fibroblasts and in the Vero cells shared at least some epitopes. The Western blot analysis of the purified membrane fraction antigens, which reacted with the monoclonal and polyclonal antibodies, detected a double band with a molecular mass of approximately 60 kDa. Not only immunofluorescence staining but also electron and immunoelectron microscopy studies evidenced the receptor localization in the plasma membrane. In this manner, we reported the isolation and partial characterization of a new Pixuna virus receptor in the plasma membrane of chicken embryo fibroblasts in culture. The data obtained demonstrated the receptor significance for the penetration of Pixuna virus into fibroblasts and mammalian cell and the related importance of designing new antiviral drugs by blocking the mechanism of receptor penetration of the virus into the cells.

Alphavirus↗
PubMed1985

[Proteolytic and elastase activities of Pseudomonas aeruginosa].

We studied 20 strains of Pseudomonas aeruginosa in its ability to produce proteolytic enzymes. Three different culture media were used: one containing salts and yeast; another one, the dialysed brain-heart-broth fluid and the third, brain-heart-broth. The best was the last one. The purification of the enzymes was performed by precipitation with ammonium sulphate and Sephadex G--100 gel filtration. The number of enzymes acting on casein were demonstrated by means of zymogram previously separated by polyacrylamide gel electrophoresis (Fig. 2). All the strains acted on gelatin and 80% of them on elastin. 80% of the 20 strains studied showed a correlation between the activity on elastin and the activity on casein (Fig. 1). 25% of the strains showed the presence of two enzymes using zymogram and 75% only one enzyme. The results were independent of the culture medium used. Strains recently isolated showed to produce a high level of proteolytic enzymes. When the strains were kept in the laboratory the activity decreased to low levels until almost disappeared (Fig. 1). When the recently isolated strains showed two proteolytic enzymes by zymogram, the less active one disappeared throughout the time when kept in the laboratory. The composition of the purified enzymes were proteic in nature; neither lipoprotein nor glycoprotein were evidenced.

Bacterial Proteins↗
PubMed1984

[Propagation of Pixuna virus in rat embryo cultures].

The behaviour of cell cultures from 11 to 18 days-old Swiss albino mouse embryo infected with Pixuna virus was studied. Eleven day-old embryo cultures showed to be a permissive system supporting a productive and cytocidal infection. In contrast, the 13 to 18 day-old embryo cultures were also permissive and productive but no evidence of cytopathic effect was observed. D-glucosamine did not affect the infectivity titer of the Pixuna virus when 11 day-old embryo cultures were used. In these cultures the eclipse phase was observed between 15 and 90 min post-absorption (Figure 1).

Animals↗
PubMed1983

[Fractions from mouse brain which non-specifically inhibit the hemagglutination of various togaviruses].

Brain fractions isolated from Swiss albino mice were studied from the physical, chemical and biological viewpoints. The isoionic point gave a value of 4.16 +/- 0.17 indicating the presence of acid groups. UV absorption experiments showed an opening of the structure when the fractions were heated. The presence of neuraminic acid group was demonstrated using o-phenanthroline and, when heated, the structure exposed the hidden neuraminic acid. The biological property of inhibiting viral hemagglutination increased when the fractions were heated. EEE virus was used as hemagglutinating antigen. The treatment with alpha-chymotrypsin destroyed the inhibiting viral hemagglutination property in 120 seconds. Polyacrylamide gel electrophoresis showed that the fractions are proteic in nature. Glyco- and lipoproteins were only present in the fraction with the inhibitory property. Only neutral lipids were demonstrated.

Animals↗
PubMed1975

Swiss albino mouse brain gangliosides: biophysical studies.

The brain gangliosides mixture of Swiss albino mice were studied from a biophysical viewpoint. The value of v found was 0.577 ml/g. The isoelectric point gave a value of 1.50, which is in agreement with the presence of sialic acid groups. The isoionic point, 2.76, is close to the pKa for sialic acid. The number average molecular weight determined in the presence of ions was 229000, while in the absence of ions it was 78000, this weight suggesting a low degree of aggregation. The[eta] value of 3.56 and 4.84 in both the presence and absence of ions would indicate an asymmetrical micelle and/or more solvate than a rigid or impermeable sphere. The value of S020, w in the presence of ions was 9.19, while in their absence it was 7.65, corresponding to a lower molecular weight coincident with that found for Mn. Hydrodynamic relations permit the supposition that the brain gangliosides mixture of Swiss albino mice is not a symmetrical micelle, since the frictional and symmetry ratio found is equal to 1.29, which corresponds to an axial ratio of 6. The value of D is equal to 2.30 X 10(-7) cm2/sec; this fact is even more suggestive that we are not dealing with a symmetrical micelle. It was not possible to calculate the molecular weight using equations under the assumption that gangliosides are a spherical micelle. It was concluded that they might be a prolate ellipsoid of revolution.

Animals↗
PubMedDate not supplied

[Partial characterization of the Pixuna virus receptor present on erythrocytes of one-day-old chicks].

A study was undertaken to evaluate the physical, chemical and immunological aspects of a receptor for Pixuna virus present on 1-day-old chicken erythrocytes. The proteases trypsin and chymotrypsin were able to expose more binding sites on the erythrocytes, increasing the hemagglutinating titer (p < 0.001). Membrane components from red blood cell membranes (ROG) were extracted with the nonionic detergent octyl glucoside. ROG could bind to Pixuna virus and prevent hemagglutination. When ROG was filtered through a 0.22 mu filter, the activity was lost, but the filtrate inhibited plaque formation in Vero cells. The membrane components did not lose activity when kept at temperatures from -5 degrees C to -134 degrees C for months. After heating at 37 degrees C for 1 h and/or at 75 degrees C for 15 min the activity remained constant. A rabbit policlonal antiserum against the membranes gave precipitin lines in ID and in CIEF that disappeared after the enzymatic treatment, but the proteases did not affect the activity to produce hemagglutination-inhibition. Similar results were obtained when a mouse antiserum against ROG was used. The present study showed that the receptor for Pixuna virus present on 1-day-old chicken erythrocytes is not proteic in nature. The membrane components, ROG, with the property of inhibiting hemagglutination, contain proteins but they were not essential for the activity. It appears that the active compound was not able to produce antibodies in these experimental conditions. ROG had two different kinds of receptors: one that was able to produce hemagglutination-inhibition and another one with the property to inhibit plaque formation in Vero cells. Apparently, lipids would be involved in the hemagglutination-inhibition activity.

Animals↗