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Biomedical subjects

B Pozzetto

Publications and source records attributed to B Pozzetto.

At least 91 records · Page 5Linked to original sources
PubMed1992

Monoclonal antibody specific for the cellular receptor of echoviruses.

Cell lines of primate origin carry membrane receptors which are specific for echoviruses (EV). The present report describes isolation and characterization of a monoclonal antibody (Mab 143) reacting with the membrane of KB cells. The Mab was selected for its protection of different cell lines from primate origin against the CPE of EV-11. This protection was found to extend to most EV serotypes and to coxsackievirus A9, while the replication of several other picornaviruses was not affected. The fluorecein isothiocyanate labelled Mab did not react with cell lines from bovine, canine, or rabbit origin, but bound specifically to the cell lines from human or simian origin. These results suggest that a unique receptor site is used by most EV serotypes for binding onto and penetration into susceptible cells.

Animals↗
PubMed1992

Evaluation of five commercial tests: complement fixation, microparticle agglutination, indirect immunofluorescence, enzyme-linked immunosorbent assay and latex agglutination, in comparison to immunoblotting for Mycoplasma pneumoniae serology.

A panel of 68 serum specimens from 41 subjects exhibiting various immunological patterns to Mycoplasma pneumoniae as determined by detection of a 180 kDa protein in immunoblotting was used to compare five commercially available tests based on different methods: complement fixation test (CFT), microparticle agglutination (MAG), indirect immunofluorescence assay (IFA), enzyme-linked immunosorbent assay (Elisa), and latex agglutination (LA). The tests were performed according to the manufacturers' instructions. For the determination of immunity to M pneumoniae, the five tests were in good accordance with immunoblotting: sensitivity was 100% for all the five assays, specificity ranged from 95.6% (MAG) to 82.6% (Elisa) and overall agreement ranged from 98.2% (MAG) to 92.8% (Elisa). The comparisons of antibody rates obtained by the four quantitative tests (CFT, MAG, IFA, Elisa) showed correlation coefficients ranging from 0.87 (CFT-IFA) to 0.67 (CFT-Elisa). Six significant antibody rises demonstrated by immunoblotting patterns were detected by all the tests but Elisa in one case. As a whole, the commercial assays gave satisfactory results for routine determination of immune status to M pneumoniae: CFT was the cheapest test and MAG and LA were the easiest to perform.

Adolescent↗
PubMed1991

[In vitro bactericidal effect of temafloxacin and tosufloxacin against streptococci].

Tosufloxacin tosylate (TOSU) and temafloxacin hydrochloride (TEMA) were tested in vitro against 248 clinical isolates of various species of streptococci recovered in a hospital microbiology laboratory (Bellevue Regional Teaching Hospital). Species included S. pneumoniae (n = 20), group A streptococci (n = 22), group B streptococci (n = 30), group G streptococci (n = 17), group D S. bovis (n = 19), Enterococcus faecium (n = 45), Enterococcus faecalis (n = 28), S. sanguis (n = 21), S. milleri (n = 29) and S. mitis (n = 17). Activities of each of the two study drugs were evaluated comparatively with two other fluoroquinolones, i.e., ciprofloxacin (CIP) and pefloxacin (PEF). Activities of each of these four antibiotics, expressed as the MIC 90%, varied as follows according to the species of streptococci: TOSU, 0.25 to 1 mg/l, TEMA 0.5 to 2 mg/l, CIP, 1 to 4 mg/l and PEF 8 to 32 mgl. Overall, TOSU and TEMA exhibited the greatest activity of the various species. The size of the inoculum had no significant effect on MIC values.

Anti-Infective Agents↗
PubMed1991

[In vitro effect of new fluoroquinolones and betalactamines combinations against enterococci].

Combinations of one of the new fluoroquinolones (ciprofloxacin, temafloxacin or tosufloxacin) with a betalactam (amoxicillin, piperacillin, or imipenem) were tested in vitro using the checkboard method against 28 strains of Streptococcus faecalis recovered in 1990 from a variety of specimens. No instance of antagonism (FIC greater than 2) was recorded. Effects of the two agents were usually additive (0.5 less than FIC less than or equal to 1). An indifferent effect (1 less than FIC less than or equal to 2) was seen in 32.1% of cases (9 strains) with the amoxicillin-tosufloxacin combination. Synergy (FIC less than or equal to 0.5) was uncommon with combinations including imipenem: effects were synergistic for only three strains with imipenem and either ciprofloxacin or tosufloxacin and for six strains with the imipenem-temafloxacin combination. Synergy was more common with combinations including ciprofloxacin and either piperacillin (10 strains, 35.7%) or amoxicillin (13 strains, 46.4%).

Amoxicillin↗
PubMed1990

Detection of immunoglobulin G, M, and A antibodies to enterovirus structural proteins by immunoblot technique in echovirus type 4-infected patients.

Paired serum specimens from 24 patients with echovirus (EV) type 4 infection by virus isolation were tested by the immunoblot technique for the presence of IgG, IgM, and IgA antibodies to EV4 structural proteins. Single sera from 20 patients without neutralizing enterovirus IgM were used as controls. All the sera from EV4-infected patients had IgG antibodies to VP1 of EV4 but also 13 out of the 20 controls. 23 out of 24 EV4-infected patients elicited IgM and IgA specific antibodies to VP1, a pattern highly significant as compared with controls (3/20 for IgM and 8/20 for IgA). In 16 out of the 24 EV4-infected patients, the IgM antibodies were also directed against VP2 (versus 2 out of 20 in the control group). Anti-VP2 IgA were detected in 4 out of the 24 EV4 patients (versus 0 in controls). The 24 paired sera from EV4-infected subjects were also tested by immunoblot technique against three other enteroviruses: EV21, coxsackievirus A9 and poliovirus 1. Cross-reactivities were observed to a large extent against VP1 and VP2 proteins with the three classes of antibodies. These results confirm the data of previous studies on the reactivity of IgM antibodies to various structural proteins that IgG antibodies react exclusively to VP1. Furthermore, this study demonstrates the occurrence of circulating IgA antibodies directed to VP1 and sometimes VP2 in the course of enterovirus infection. The potential interest of this latter finding for diagnosis requires further investigation.

Adult↗
PubMed1990

Nosocomial infection with Legionella pneumophila serogroup 1 and 8 in a neonate.

A case of pneumonia related to 2 serogroups (1 and 8) of Legionella pneumophila (Lp) in a 10-day-old boy is described together with the epidemiological survey in the maternity ward which made it possible to establish its nosocomial origin. Rodshaped bacteria reacting with an Lp genus-specific monoclonal antibody and serogroup 1 and 8 polyclonal sera were detected in bronchoalveolar lavages (BAL) collected on day 13. Serogroups 1 and 8 were recovered from cultures of BAL collected on days 12 and 13. Fourfold or more antibody rises to serogroups 1, 5, 8 and 10 of Lp were observed in sequential serum specimens. Water samples collected from the tank and mixer of the maternity ward grew serogroups 1 and 8 of Lp. Serogroup 1 was detected in large amounts in water samples taken at several points of the hot water supply system and from the oxygen nebulizers and the feeding-bottle heater. Analysis of the Lp serogroup 1 strains isolated from the water by subgroup-specific monoclonal antibodies revealed the presence of 4 different subgroups, one of which was identical to the Lp 1 subgroup isolated from the neonate's BAL. This latter subgroup, reactive with McKinney monoclonal antibody Mab 2, has been described as highly virulent. No other case of legionellosis was recorded in the maternity ward.

Cross Infection↗
PubMed1989

Detection of neutralizing IgM antibodies in the diagnosis of enterovirus infections.

Data are presented of IgM detection by a neutralization test used routinely in 1,062 patients. Antigens isolated during the period of investigation were EV4, EV7, EV11, EV18, EV21, EV24, EV33, CA9, CB2, CB4, and CB5. No difference was observed in the distribution of IgM-positive sera according to age and sex. Total antibodies are at higher titres when IgM antibodies are present. Polytypic IgM responses are not frequent (less than 10%). The frequency of the IgM-positive sera for a given serotype correlated with the frequency of isolates for the serotype except for CA9. Other than for babies under age 6 months, IgM detection is more frequent than is isolation. The susceptibility of the elderly and the frequency of IgM-positive sera among adults over age 40 years suggests possible underestimation of enterovirus infections in adults. The duration of IgM remains a major question.

Adolescent↗
PubMed1989

Ganciclovir therapy of symptomatic cytomegalovirus infection in renal transplant recipients.

We used ganciclovir to treat 11 renal transplant recipients with symptomatic cytomegalovirus infection (seven primary), including one severe, five mild and five moderate cases. Two patients exhibited a non-mechanically ventilated pneumonitis and two others a gastrointestinal involvement. Ganciclovir was used intravenously according to a schedule which took into account renal function, for a median time of 14 days. All patients survived. Cytomegalovirus infection was cured in all patients but two: in the first an early clinical relapse required a second successful ganciclovir course; in the other graftectomy was needed to control infection. Graft was lost in an additional cured patient. Ganciclovir was well tolerated, especially with regard to haematological status. At the current follow-up of at least one month after the end of ganciclovir therapy, no further clinical relapse was observed; however, in one clinically cured patient cytomegalovirus was isolated from blood one week after ganciclovir cessation. These encouraging preliminary data suggest that ganciclovir therapy should be started as soon as cytomegalovirus infection is suspected, especially in cytomegalovirus seronegative recipients receiving a seropositive graft.

Adult↗
PubMed1989

Comparative evaluation of immunoglobulin M neutralizing antibody response in acute-phase sera and virus isolation for the routine diagnosis of enterovirus infection.

A total of 314 patients exhibiting symptoms consistent with a viral disease provided, during the early stage of hospitalization, at least one specimen from a peripheral site (throat or stools or both) and a serum specimen in order to evaluate the neutralizing immunoglobulin M (IgM) antibody response in acute-phase serum in comparison with virus isolation for the rapid diagnosis of enterovirus (EV) infection. IgM antibodies were fractionated by ion-exchange chromatography and tested by seroneutralization against the various types of EV that have been recently circulating. A total of 189 patients (60%) were negative, and 21 (7%) were positive by both methods; in 51 patients (16%), a virus was isolated without IgM antibody response; 53 patients (17%) showed the opposite pattern. In all age groups except for children under 6 months, the frequency of positive results was higher with IgM serology than with virus isolation (27 and 22%, respectively). Apart from meningitis, for which isolation was more efficient, the other clinical conditions were associated with similar percentages of positivity by both methods. Regarding the 21 cases with positive results by the two techniques, the same serotype was detected in 9 cases and different serotypes were detected in 12, suggesting crossreactivities. Thus, IgM neutralizing antibody response on acute-phase serum appears to be of limited value in the rapid diagnosis of acute EV infection but may prove useful for the investigation of the wide range of chronic diseases associated with EV.

Acute Disease↗
PubMed1988

Commercial monoclonal antibodies for rapid detection of respiratory syncytial virus by direct immunofluorescence.

A commercially available direct immunofluorescence (IF) test using a reagent consisting of a pool of two monoclonal antibodies against selected surface and internal proteins of respiratory syncytial virus (RSV) was evaluated in comparison with the indirect IF technique using a commercial bovine anti-RSV hyperimmune serum for the rapid detection of RSV in nasopharyngeal aspirates from 228 hospitalized children. Overall agreement between the two IF methods was 95%. The direct IF test was quicker to perform and easier to interpret than the indirect IF test.

Antibodies, Monoclonal↗
PubMed1988

Incidence of cytomegalovirus infections in renal transplant patients treated with conventional or cyclosporin therapy.

The incidence and severity of cytomegalovirus (CMV) infection was examined in groups of consecutive renal transplant patients: group A (50 patients) transplanted from August 1984 to October 1985 received cyclosporin (from the day of transplantation) and steroid therapy; group B (50 patients) transplanted between June and July 1984 received conventional therapy (azathioprine and steroids, and antilymphocyte globulin for 14 days). In groups A and B there were respectively 5 (10%) and 14 (28%) seronegative patients prior to transplantation (CMV antibody titre less than 128 by ELISA); the overall incidence of CMV was 38% vs 74% (P less than 0.001); the incidence of primary infection was 0% (0 of 5) vs 36% (5 of 14) (NS); the incidence of secondary infection was 42% (19 of 45) vs 89% (32 of 36) (P less than 0.00001); and the total incidence of symptomatic infection was 10% vs 26% (P = 0.04). Thus we conclude that initial cyclosporin therapy leads to a reduction in CMV infection.

Antilymphocyte Serum↗