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Biomedical subjects

M A Longo

Publications and source records attributed to M A Longo.

8 recordsLinked to original sources
PubMed1998

Sporadic hepatitis C virus infection: a case-control study of transmission routes in a selected hospital sample of the general population in Italy.

A case-control study was performed on 9,175 Italian adult outpatients in 5 hospitals in Rome. The study was carried out to clarify the role of some less investigated risk factors (RF) in the spread of hepatitis C virus (HCV) infection. All subjects were contacted by interviewers, who completed a questionnaire. Their sera were stored and subsequently tested for both HCV and hepatitis B virus core (HBc) antibodies. 365 subjects, positive for anti-HCV and anti-HBc-negative, and who had denied intravenous drug use (IDU) (cases) were compared with an equal number of suitable random controls negative for anti-HCV and anti-HBc. Gender, age and region of birth and residence were matched. The prevalence of 13 RFs were statistically compared by univariate and multivariate analysis. A positive anti-HCV test was significantly associated, by multivariate analysis with intravenous treatments and minor surgical procedures (both before 1975) (p < 0.001), blood transfusions (before 1991) (p < 0.01), diabetes (p < 0.01), and deliveries in hospital (p < 0.05) (both before 1975). After 1975 (1991 for transfusions), all associations lost their significance. Intra-familial (sexual and non sexual), occupational RFs and dental care were not significantly associated with the presence of anti-HCV. We suggest that non-disposable syringes, commonly used until 1975 in Italy for i.v. treatments, have been the major route for HCV transmission in Italy among non-IDU subjects.

Adult↗
PubMed1997

Influence of surface hydrophilic/hydrophobic balance on enzyme properties.

Two different enzyme surface modifications were carried out in order to alter the protein hydrophilic/hydrophobic balance in opposite directions and to observe the effects induced on enzyme properties. First, a novel chemoenzymatic glycosylation method was applied, which resulted in a higher enzyme surface hydrophilic character. Then, an amphiphilic polymer, PEG, was bound to the enzymes by chemical means, and it brought about an increase in the global hydrophobic character. Two different enzymes, alpha-chymotrypsin and Candida rugosa lipase, were studied, and in all cases, several degrees of modification were obtained. Then, the modified biocatalysts were thoroughly investigated, and the influence of the variation of surface hydrophilic/hydrophobic balance on hydrolytic activity, hydrolysis kinetic parameters, synthetic activity and thermal stability was assessed.

Animals↗
PubMed1995

A novel chemoenzymatic glycosylation strategy: application to lysozyme modification.

Hen egg lysozyme has been non-specifically glycosylated using a novel two-step strategy. First, a number of sucrose molecules have been chemically bound to the protein surface lysines, then the glycosidic chains have been enzymically lengthened, using a glycosyltransferase. For this task, a fructosyltransferase and a levansucrase have been tested, the latter appearing as the most effective one. In all cases, reactions have been optimised and several degrees of modification have been obtained. Finally, the effects of the modifications on lysozyme hydrophobicity, hydrolytic activity, hydrolysis substrate affinity and thermostability have been assessed.

Animals↗
PubMed1992

Diffusion of proteases in calcium alginate beads.

Diffusion of proteases from Bacillus subtilis and Serratia marcescens within calcium alginate beads has been assayed, and the experimental data fitted into a mathematical model for diffusion into a finite volume liquid medium. Values of effective diffusivity were calculated for the studied proteases and compared with the available data in the literature for molecules of lower molecular weight.

Alginates↗
PubMed1989

[Tumors of the brain stem: anatomo-pathologic study of 35 necropsy cases].

Brain stem tumors are rare and are usually treated without histological diagnosis. Its incidence varies in literature between 1.09% and 17.5% of all cerebral tumors. The objective of our study is to present a casuistic of these tumors in 28500 necropsies performed from 1952 till 1985 at the Department of Pathology, Santa Casa Hospital, São Paulo. We emphasize neuropathologic aspects, and compare our cases with those of other series. Also, we point out those tumors which are most frequent in this region, with the aim of possibly contributing to a better therapeutic approach. We used some clinical data and pathological diagnosis, and localized the tumor in the brain stem. Its microscopic diagnosis was determined according to the World Health Organization criterion. Among 428 intracranial tumors observed, 35 were localized in the brain stem. Intrinsic tumors and metastasis were included, and excluded those tumors which infiltrated the brain stem. Greatest incidence occurred in the first decade and cerebral edema was the predominant cause of death. Preferential topography was in the pons and the most frequent tumor was glioblastoma multiformis (19 cases). Metastasis ranked second (9 cases), being mostly from lungs. Some authors oppose tumor biopsy in this region because of high surgical risk. We do not agree with this opinion. We believe that the diagnosis of glioma is important to rule out the characteristics of malignancy. We can not leave without considering the diagnosis of other pathologies which can cause expansion in the brain stem. Therapeutical approach can be more adequate with the histological diagnosis of glioma or of other possibilities as shown here.

Adolescent↗
PubMed1989

Nonfatal demyelinating encephalomyelitis induced by coronavirus (JHM strain) infection in mice.

C3H mice infected intravenously with the JHM strain of coronavirus showed high incidence of demyelination (44.8%) and low incidence of encephalitis-induced mortality (6.9%). High titers of virus were detectable in the brain and liver of mice only during the first 3 to 12 days of infection (10(3) and 10(4) PFU/g, respectively). Most of the animals recovered from the first phase of disease and some (11.1%) came down with paralysis 6 to 7 weeks after the infection, with no histological changes or virus detectable in their tissues.

Animals↗