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Biomedical subjects

E Romero

Publications and source records attributed to E Romero.

At least 91 records · Page 5Linked to original sources
PubMed1989

Detection of IgG anti-HIV antibodies in mice experimentally infected with HIV-1.

In the present work we report our preliminary data demonstrating the susceptibility of mouse to HIV infection. IgG antibodies were found in mice intraperitoneally inoculated with H9/HTLV-IIIB infected cells. Infected mice showed a humoral response and the antibodies detection includes specific immunoglobulin directed against the major gene product of HIV. Two weeks after infection with HIV infected cells we detected in mice IgG antibodies to p24, and the reactivity to gp41 was observed as early as reactivity to p24 and persisted throughout observation period. The persistence of specific antibody response to HIV after one year seems to demonstrate the possibility of the use of the mouse as animal model for HIV in vivo experiments. Studies concerning the degree and kinetic of HIV infection in mouse are in progress in our laboratory.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Beta-lactam resistant Pseudomonas aeruginosa strains emerging during therapy: synergistic resistance mechanisms.

The emergence of beta-lactam resistant strains of Pseudomonas aeruginosa during treatment was studied. Three different strains present before treatment persisted with changes in their beta-lactam resistance during treatment. The isolates before and after therapy were studied for beta-lactamase production and permeability barrier. The increased beta-lactam resistance was correlated with an increased permeability barrier. In order to verify if the permeability barrier was correlated with changes in outer membrane proteins, outer membrane preparations were analyzed by SDS-PAGE. Several differences were observed between the OMP profiles of the post therapy and the pre therapy isolates. Furthermore, an analysis of PBPs pattern of strains studied was carried out and alterations in target proteins were observed.

Anti-Bacterial Agents↗
PubMed1988

Antiviral activity of Chamaecyparis lawsoniana extract: study with herpes simplex virus type 2.

Ethanolic extract of the green part of Chamaecyparis Lawsoniana was tested for antiviral activity and toxicity in tissue culture. All experiments were carried out in confluent human embryo lung fibroblasts. Treatment of fibroblast cells with extracts after viral inoculation was effective in inhibiting the replication of herpes simplex virus type 2 (HSV-2). The critical time for virus inhibition was 4 to 5 h after virus absorption. The antiviral activity was assayed employing the techniques of viral plaque and yield reduction. Toxicity of Chamaecyparis Lawsoniana in uninfected cells was studied as alteration of cell morphology, cellular viability and inhibition of host cell DNA synthesis. Herpes simplex virus inhibition occurred in presence of extract concentration of 0.5 micrograms/ml, whereas concentrations exceeding 5 micrograms/ml and 140 micrograms/ml were found to be cytotoxic when evaluated with inhibition of host DNA synthesis and cellular viability respectively. Results suggest that further investigations concerning the isolation of substances responsible for antiviral activity and an effort to define the mechanisms of action are warranted.

Antiviral Agents↗
PubMed1987

Modifications of DNA-gyrase and of permeability in a norfloxacin-resistant clinical isolate of Providencia stuartii.

We obtained a clinical isolate of Providencia stuartii showing a high level of resistance to norfloxacin and to other 4-quinolones, whose target is the enzyme DNA-gyrase. This strain showed resistance also to beta-lactam and aminoglycoside antibiotics. In order to detect modification of DNA-gyrase, we performed supercoiling assays in vitro in presence of norfloxacin and ciprofloxacin. Furthermore, outer membrane proteins, which are involved in permeability mechanisms, were analyzed on SDS-polyacrylamide gels. Results showed that both modifications in DNA-gyrase and changes in outer membrane proteins can be held responsible for resistance to 4-quinolones; moreover, these modification are probably supported by a third mechanism of resistance.

Bacterial Outer Membrane Proteins↗
PubMed1987

Preliminary characterization of an inhibitory activity of fetal bovine serum on the infectivity of rotavirus strain SA-11.

In the present work we studied non antibody inhibiting activity present in fetal bovine serum and active to Rotavirus infectivity and growth in cell cultures. This inhibitor was revealed by an in vitro neutralization test and characterized by gel filtration and chemical and enzymatic treatments. Furthermore, commercial preparations of bovine serum proteins were tested for inhibitory activity. Our results show that serum inhibition is partially resistant to trypsin and neuraminidase treatments but completely destroyed by KIO4. A similar activity was observed in a commercial serum bovine fraction containing predominantly alpha-globulins. These results seem to indicate that glycoproteins, and their glucidic components are the molecules predominantly involved in serum inhibition towards Rotavirus infectivity.

Animals↗
PubMed1986

Prevalence of antibody to human coronaviruses 229E, OC43 and neonatal calf diarrhea coronavirus (NCDCV) in patients of Northern Italy.

A seroepidemiological study for detection of antibody to human coronaviruses OC43, 229E, and neonatal calf diarrhea coronavirus (NCDCV), has been carried out using sera collected from hospitalized patients or healthy persons through routine laboratory tests in Northern Italy. Patients tested were children and adults with different pathological diseases. Antibody detection was performed by using an indirect immunoperoxidase staining technique (for all viruses) and, in the case of OC43 and NCDCV, antibody detection was obtained even with a hemagglutination inhibition test and a plaque reduction neutralization assay. Results obtained show a significant difference in the prevalence of antibody to 229E between children and adult group. Furthermore, a different titer was observed, within the two groups, between patients affected by hematological diseases (leukemia) and patients with other diseases. Finally, our data seem to confirm previous studies reporting a very high prevalence of antibody to coronavirus OC43 but a less detectable seropositivity to coronavirus 229E.

Animals↗
PubMed1986

Coronavirus inhibitor in human sera: age distribution and prevalence.

We studied the distribution, in human sera, of non antibody serum inhibitor active towards human OC43 and bovine NCDCV coronaviruses. Antibodies to coronaviruses, present with high prevalence in human sera, were filtered by Protein A Sepharose CL 4B column. In the present work we tested sera of newborns, infants, young children and adults. Inhibitory activity was revealed in all sera except these from newborns. This non antibody inhibitor was tested by a plaque-reduction assay.

Adult↗
PubMed1986

Serum inhibitor of coronaviruses OC43 and NCDCV: a study in vivo.

It is well known that some strains of coronaviruses, such as human OC43 and bovine NCDCV, are highly inhibited by non antibody factors present in sera of different mammalian species and sensitive to phospholipase-C treatment. So far this inhibitor has only been revealed in vitro experimental procedures with coronavirus strains adapted to growth in human lung fibroblast cell cultures. The purpose of this work was to ascertain whether this inhibiting activity was also effective "in vivo". In order to detect the "in vivo" activity, we used suckling mice which have been shown to be the animals most sensitive to infection with these viruses. Our results demonstrated that the same non antibody inhibitor is able to neutralize viral infection both "in vivo" and "in vitro".

Animals↗
PubMed1986

Fluorescence polarization immunoassay to determine aminoglycoside modifying enzymes activity.

The possible use of polarized-immunofluorescence to evaluate aminoglycoside-modifying enzyme activities has been investigated. The TDX instrument was used to determine the residual quantity of aminoglycoside following inactivation during the assay procedure. Through the spectrum of the modified aminoglycoside antibiotics the enzymes encoded on eleven R-factors from clinical isolates of Enterobacteriaceae have been identified.

Acetyltransferases↗
PubMed1985

Degradation of human fibronectin by strains of E. coli K12 carrying R factors from Klebsiella pneumoniae.

We studied the ability to degrade human fibronectin by strains of E. coli K12 carrying R factors from Klebsiella pneumoniae, previously shown to possess a caseinolytic activity. The preliminary data obtained showed that at least two of these R+ strains are able to degrade fibronectin to small peptides retaining the gelatin-binding site of the molecule. We also found indications of non-fibronectin gelatin-binding polypeptides secreted by the strains tested into the culture broth. The possible significance of this bacterial property as a factor of pathogenicity is discussed.

Carrier Proteins↗
PubMed1985

R factor-mediated adhesiveness to mammalian cells in E. coli K12.

We checked the possible effects of the standard plasmids of known compatibility groups on the ability of three strains of E. coli K12, J62, J53 and C600, to agglutinate human and guinea pig erythrocytes and to adhere to cultures of human epithelial cells. The results obtained showed that under defined experimental conditions one plasmid, R478, from a clinical isolate of Serratia marcescens is able to modulate the adhesive properties of the strain J62 which lacks adhesiveness. On the contrary, the same factor did not alter the ability of strains J53 and C600 to agglutinate erythrocytes and to adhere to human epithelial cells in culture, nor did it induce adhesive properties in wild-type strains of E. coli from clinical isolates that lacked them. This would suggest a possible plasmidic control of chromosomally encoded surface structures that mediated adhesiveness of E. coli to mammalian cells.

Adhesiveness↗
PubMed1985

[Prospective use of immunofluorescence polarization in the study of enzymes modifying aminoglycosides].

A number of assays have been described for aminoglycoside-modifying enzymes; the aim of our investigation was to check the validity of polarized immunofluorescence assay for aminoglycoside enzymes. We have studied three enzymes encoded by R-factors from clinical isolates of Enterobacteriaceae conferring various patterns of aminoglycoside-resistance. The assay resulted valid: this is a simple, rapid and sensitive method.

Aminoglycosides↗
PubMed1985

[The role of beta-lactamases and the permeability barrier in resistance to beta-lactam antibiotics].

The role played by beta-lactamases and by permeability barrier in resistance to beta-lactam antibiotics was investigated in 250 clinical isolates of Enterobacteriaceae. The data obtained showed that in 73 strains (52.9%) was a significant correlation between the specific enzyme activity and resistance, however in 38 strains (27.5%) an essential role was played by permeability barrier because the addition of subinhibitory levels of EDTA produced markedly reduction in the MIC.

Anti-Bacterial Agents↗
PubMed1985

Phosphatidyl-serine inhibition of OC43 and NCDCV coronavirus infectivity.

Human OC43 and bovine neonatal calf diarrhoea coronavirus (NCDCV) are known to be inhibited by non-antibody factors present in sera of different mammalian species, including man and cattle. Such an inhibitor is also present in fetal calf serum generally used for growing and maintaining cell cultures, thus influencing the viral infectivity titer. Previous reports refer to the effectiveness of phospholipase C treatment in eliminating the inhibiting activity. In order to detect the compound possibly involved in coronavirus growth inhibition (among the phospholipids naturally present in mammalian sera), we tested several phospholipids with hemagglutino-inhibition test and plaque reduction assay. Only phosphatidyl-serine seemed to be effective on Coronavirus OC43 and NCDCV, as detected by plaque-reduction assay, but not by hemagglutino-inhibition test.

Animals↗
PubMed1984

The modulation of the calcium pump of human red cells by Na+ and K+.

The sidedness of Ca2+-pump activation by Na+ and K+ was studied by atomic absorption spectrophotometry in human erythrocyte ghosts, which had been prepared in dextran solutions and resealed to alkali cations. When ghosts were incubated in an all-choline medium, the increase in Na+i elicited an inhibitory-stimulatory effect on Ca2+ extrusion. By contrast, only a stimulatory action was induced when choline was replaced by Na+o. A dual effect on active Ca2+ efflux was also produced by increasing K+i or K+o. The biphasic response to the latter, however, was absent from high-K+ ghosts. Furthermore, the stimulation obtained at high K+o was additive to that elicited by K+i. The results suggest that Na+ and K+ stimulate the Ca2+ pump of human red cells through two different mechanisms. The first one appears to be an electric coupling between Ca2+ efflux and the external activating cation. The other seems associated with the molecular reactions of the Ca2+-pump protein.

Calcium↗