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Biomedical subjects

N Orsi

Publications and source records attributed to N Orsi.

At least 109 records · Page 6Linked to original sources
PubMed1980

Relationship between enzymatic modifications of serum low density lipoproteins and their haemagglutination inhibiting activity towards Sindbis virus.

The chemical structure of human serum low density lipoproteins (LDL) involved in the inhibition of the haemagglutination by Sindbis virus was studied. Separation of lipoproteins into their protein and lipid components demonstrated that the inhibiting activity is almost completely due to the lipid moiety. The treatment of LDL and extracted lipoprotein lipids by phospholipase A2, C and D produced different effects and in particular a marked increase in the HI titre by the action of phospholipase A2. Moreover treatment with glycosidases significantly reduced the HI titre of LDL, thus suggesting the importance of carbohydrate moiety in the inhibiting lipoprotein molecule.

Apolipoproteins↗
PubMed1980

Capacity of staphylococci to grow in the presence of ovotransferrin or CrCl3 as a character of potential pathogenicity.

A total of 150 strains of staphylococci, clinically isolated, were tested for sensitivity to ovotransferrin (conalbumin). Among these, all the 50 coagulase-positive, mannitol-positive, and deoxyribonuclease-positive staphylococci appeared to be resistant to conalbumin, i.e., capable of growing in the presence of this transferrin. Among the other 100 strains, which were not classified as S. aureus, some appeared to be resistant and some were sensitive. The different behavior toward conalbumin is related to varying degrees of efficiency of the bacterial iron transport systems and, to test this, a simple method can be used, based on the addition of CrCl3 to the culture medium. The precipitation of iron produced by chromium salts has an effect on the growth of staphylococci similar to that produced by conalbumin and reveals the differences in the iron transport systems which occur in the genus Staphylococcus.

Biological Transport↗
PubMed1980

Separation by affinity chromatography of human very low and low density lipoproteins inhibiting Sindbis virus haemagglutination.

The haemagglutination-inhibiting activity of human serum towards Sindbis virus is linked to very low and low density lipoprotein classes, in particular to their lipid component. To investigate the specific role played in this inhibition by carbohydrates contained in the molecule, inhibitor separation was carried out by Concanavalin A-Sepharose affinity chromatography. A different behaviour among the inhibiting molecules in relation to the carbohydrate content was observed. The importance of mannose for the biological activity of the inhibitor is discussed.

Carbohydrates↗
PubMed1979

Different sensitivity of hemagglutinating and hemolytic activities of Sendai virus to non-antibody inhibitors.

Research was carried out in order to verify if some components of human serum, which are capable of inhibiting the hemagglutination by Sendai virus, are active even towards the hemolysis by the same virus. It was ascertained that both orosomucoid and low-density lipoproteins obtained by floatation had no action on the hemolysis by Sendai virus while lipoproteins precipitated with dextrane sulphate showed a certain inhibiting effect. This action however is not due to lipoproteins but is probably related to some substances used in the method of precipitation.

Antibodies, Viral↗
PubMed1978

[Studies of the possible importance of complement in increasing the hemagglutination-inhibiting activity of rabbit IgM against Sendai virus].

An investigation has been carried out in order to ascertain the effect of the presence of complement on the HI antibodies of the IgM class obtained in rabbit against Sendai virus. Contrary to the results obtained by some AA. with other viruses, in this case the presence of complement in the form of fresh guinea-pig serum has not modified the HI titre. It has however been demonstrated that in the guinea-pig serum an inhibitor is present, which is active towards Sendai virus and can be identified as a 19S alpha-globulin.

Animals↗
PubMedDate not supplied

Effect of isoflavans and isoflavenes on the infection of Frp/3 cells by hepatitis A virus.

The effect of 6,4'-dichloroflavan and of isoflavan and isoflavene derivatives on hepatitis A virus (HAV) infection in a monkey cell line (Frp/3 cells) was studied. These compounds were not virucidal and had no measurable effect on the adsorption of virus to the cells at 0 degrees C, whereas they exerted an inhibitory effect on viral antigen synthesis when incubated with the infected cells during HAV multiplication. Among the substances tested, 6,4'-dichloroflavan and 6,4'-dichloroisoflavan showed the highest activity. These compounds are postulated to interact with an early stage (penetration and/or uncoating) of HAV infection.

Antiviral Agents↗
PubMedDate not supplied

Electrostatic interactions in the early events of VSV infection.

The importance of electrostatic interactions in the early phases of vesicular stomatitis virus (VSV) infection has been investigated in susceptible cells of different origin, human (HeLa) and avian (CER), by using some polyanions (heparin, polygalacturonic acid and mucin) and polycations (polymyxin B sulphate, poly-L-lysine, protamine, histone and polybrene). In HeLa cells, the attachment of VSV was enhanced by polymers having a positive charge and inhibited by those having a negative charge. In CER cells, all the polyanions tested reduced virus infection. Among the polycations, histone, polymyxin B sulphate and poly-L-lysine enhanced virus plaque formation while protamine and polybrene reduced virus attachment. The effect of polyions on VSV particles and on cell membrane receptors has also been investigated. The analysis of the results obtained suggest that, although electrostatic interactions play an essential role in the binding of VSV to the cell membrane, more specific structural features appear to be required for viral attachment to occur.

Animals↗
PubMedDate not supplied

Inhibition of herpes simplex, rabies and rubella viruses by lectins with different specificities.

A series of eleven lectins were investigated for their inhibiting activity towards herpes simplex type 1, rabies and rubella viruses. Herpes simplex virus adsorption was inhibited by Limulus polyphemus (LPA), Canavalia ensiformis (ConA) and wheat germ (WGA) agglutinins, whereas Bauhinia purpurea (BPA) and soybean agglutinins were more effective if present during viral replication; rabies virus attachment to susceptible cells was prevented by LPA and Narcissus pseudonarcissus (NPA) agglutinin whereas WGA and BPA were inhibitory at a later step; rubella virus multiplication was affected only after the attachment step by NPA, ConA and WGA.

Animals↗
PubMedDate not supplied

Effect of natural and semisynthetic polymers on rabies virus infection in CER cells.

Different natural and semisynthetic polymeric carbohydrates inhibited rabies virus infection in chicken-embryo-related cells by interfering with the virus adsorption process; a dose-dependent relationship was exhibited. Among polysaccharides tested, the neutral polymer Scleroglucan and the negatively charged Keltrol, glyloid sulphate 4324, glyloid sulphate 4327 and alginic acid were the most effective and remained active at concentrations far below the cytotoxicity threshold. Data obtained indicated that the inhibition mechanism of polymers may be related to the ability of these compounds to bind to viral envelopes, although their interaction with cell surfaces cannot be excluded. The charge density and the polymeric backbone of the molecules seem to play a role in influencing the antiviral properties, whereas other features such as the sugar moieties do not appear to be relevant.

Adsorption↗
PubMedDate not supplied

Structure and in vitro antiviral activity of sesquiterpene glycosides from Calendula arvensis.

Previous research on the aerial parts of Calendula arvensis led to the isolation of the epicubebol glycoside 1 and of the sesquiterpene glycosides 2-5 based on the alloaromadendrane skeleton. A further investigation has revealed two new glycosides, 6 and 7, derived from the same sesquiterpene, the structures of which were elucidated by spectral studies. Furthermore a series of antiviral tests has been performed on glycosides 1-7 by examining their ability to interfere with rhinovirus 1B and vesicular stomatitis virus infection in vitro. Only glycoside 1 slightly reduced rhinovirus multiplication. All the compounds were able to inhibit vesicular stomatitis virus infection, 1 and 2 being the most effective.

Animals↗
PubMedDate not supplied

Detection and sequence analysis of human polyomaviruses DNA from autoptic samples of HIV-1 positive and negative subjects.

The distribution of DNA of BK and JC human polyomaviruses (BKV and JCV) was investigated in samples from autopsies of different organs in 2 groups of patients: Human Immunodeficiency Virus -1 (HIV) positive and negative. Samples from various organs were analysed by a nested polymerase chain reaction (PCR) for the non-coding control and for the VP1 regions of both viruses. The results obtained showed that BKV DNA was present in both males and females with a higher prevalence in HIV-positive subject samples (spleen: 33%; kidney: 44%; brain: 22%, uterine cervix:100%; prostatic urethra: 50%). In prostatic urethra samples of HIV-positive subjects, the JCV DNA was revealed in a low percentage (33%), while it was not found at all in uterine cervix samples of both groups. The varying presence of BK and JC viral DNA in the different organs seems to reflect the different pathogenetic attitude of these viruses. JCV was mainly present in the brain (55%), confirming its typical neurotropism and its etiological role in neurological disorders found in immunodeficient patients. BKV, on the other hand, was mainly present in the kidney (44%) and in genital organs (uterine cervix: 100%; prostatic urethra: 50%) with the latter finding favouring the hypothesis of a possible sexual transmission of BKV. Furthermore, our results confirm the crucial role of the immune system in the persistence of human polyomaviruses in the host.

Adult↗
PubMedDate not supplied

DNA content in human colon cancer and non-neoplastic adjacent mucosa.

DNA content was determined by flow cytometry in a series of 51 paired fresh tissue samples of primary colorectal carcinomas and the respective non-neoplastic adjacent mucosa in order to assess the relationship between DNA ploidy and the most commonly used prognostic factors. Aneuploidy was observed in 70.6% of the tumors and more than one aneuploid peak was present in 3.9%. Aneuploid tumor frequency was higher in left (93.3%) and right colon (64.7%) cancers than in rectal carcinomas (60.0%), and multiple aneuploid clones were detected more frequently in men than in women and in patients with advanced disease (Dukes stage D). Non-neoplastic mucosa adjacent to aneuploid tumors showed aneuploidy in 4 out of 51 samples (7.8%). The mucosa adjacent to diploid cancers had only diploid characteristics. Ploidy did not correlate with histological abnormalities. These findings suggest that DNA content as determined by flow cytometry needs further study with adequate follow-up to evaluate possible correlations with relapse-free and overall survival. Furthermore the aneuploidy of non-neoplastic mucosa provides evidence for a field defect in mucosa adjacent to colorectal cancer and supports the concept that this alteration may be of influence on carcinogenesis.

Adenocarcinoma↗
PubMedDate not supplied

[Effect of sub-bacteriostatic doses of aztreonam on the adhesion of Pseudomonas aeruginosa].

The effect of sub-inhibitory concentrations of Aztreonam towards the adhesiveness of an uropathogenic strain of P. aeruginosa was tested. The filamentous forms, morphologically altered by the action of the antibiotic, were not capable of adhering to human uroepithelial cells. This phenomenon was due to an alteration of bacterial structures responsible for the adhesion and was not related to a steric hindrance caused by the antibiotic on either the bacterial structures or the cell receptors.

Aztreonam↗
PubMedDate not supplied

[The rhabdovirus program at the Istituto Pasteur--Fondazione Cenci Bolognetti].

Studies carried out under the research program on Rhabdovirus sponsored by the Istituto Pasteur--Fondazione Cenci Bolognetti are reviewed. The program was mainly focused to investigate biologically relevant characteristics of this virus and to evaluate epidemiological and prophylactic aspects involved in sylvatic rabies control measures.

Animals↗