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B Masquelier

Publications and source records attributed to B Masquelier.

27 records · Page 2Linked to original sources
PubMed1995

Genotypic evolution of HIV-1 isolates from patients after a switch of therapy from zidovudine to didanosine.

The existence of zidovudine (ZDV)-resistant and didanosine (ddI)-resistant human immunodeficiency-1 (HIV-1) variants mutated in the reverse transcriptase (RT) gene has been previously demonstrated. In this study, we tried to follow up the genotypic changes in the RT after the switch of therapy from ZDV to ddI. We studied HIV-1 isolates from 11 patients undergoing ddI therapy. Genotypic data were obtained with differential polymerase chain reaction (PCR) and with direct sequencing after PCR. The prevalence of ZDV resistance-related mutations showed a very slow decrease, particularly when patients had been treated with ZDV for a long time. The appearance of a mutation at codon 74 seemed to be independent of the presence or absence of ZDV resistance-related mutations. The broad genotypic heterogeneity of the isolates and the complexity of the evolution in one patient's isolates plead for large sequencing studies of the RT genome in new therapeutic approaches.

Base Sequence↗
PubMed1992

HIV-1 sensitivity to zidovudine: a consensus culture technique validated by genotypic analysis of the reverse transcriptase.

In order to select and standardize a reliable assay for the analysis of sensitivity of HIV isolates to AZT, we have compared two culture methods. The first assay (Cell-Associated Isolate Sensitivity Assay: CAISA) quantified AZT-resistant HIV isolates by end-point dilution cultures of peripheral blood mononuclear cells (PBMCs) in the presence of various concentrations of AZT. In the second assay (Cell-Free Isolate Sensitivity Assay: CFISA), following a conventional isolation of HIV, dilutions of infected cell-free supernatants were cultivated with fresh normal donor PBMCs in the presence of increasing concentrations of AZT. Samples from 64 untreated and AZT-treated patients were studied by CAISA (41), CFISA (43) or both assays (20). The CFISA, which allows the determination of titration parameters with respect to various kinetics patterns of viral replication was selected, and some of the CFISA phenotypically characterized isolates were further studied by nucleotide sequence analysis of the reverse transcriptase gene. CFISA showed that isolates from untreated patients were susceptible to AZT while the frequency of resistance increased with the duration of therapy. Genotypic analysis of CFISA-resistant isolates exhibited mutations at crucial positions, particularly at residue 215. We consider CFISA as a consensus culture technique for longitudinal studies of isolates from patients receiving AZT or other analogs of nucleosides.

Cell-Free System↗
PubMed1992

[In vitro activity of vancomycin and teicoplanin against gram-positive cocci].

The activities of vancomycin and teicoplanin against 148 strains of Gram-positive cocci were tested using agar diffusion and liquid microdilution MIC determination. Tested strains included 84 staphylococci, 32 S. aureus, 52 coagulase-negative staphylococci (CNS), 52 enterococci, and 12 streptococci. Most strains (136) were susceptible to both agents, with inhibition diameters of 17 mm or more. MRSA strains exhibited lower geometric MIC means with teicoplanin (0.90 micrograms/ml) than with vancomycin (1.79 micrograms/ml); this difference was found for methicillin-susceptible S. aureus strains (1.07 and 1.38 micrograms/ml for teicoplanin and vancomycin, respectively). In contrast, methicillin-susceptible and methicillin-resistant strains of CNS exhibited similar MICs (1.60 micrograms/ml approximately). Enterococci were more susceptible to teicoplanin (MIC 0.25 micrograms/ml) than to vancomycin (MIC 1.35 micrograms/ml). Both vancomycin and teicoplanin were thus found to be consistently effective against Gram-positive cocci; however, teicoplanin proved more effective than vancomycin against enterococci and methicillin-resistant S. aureus strains and may therefore be a valuable therapeutic alternative for these multiresistant organisms.

Anti-Bacterial Agents↗
PubMed1991

In vitro assays show a dissociation of reverse transcriptase activity and core antigen (p24) production in two HIV-1 isolates from a patient receiving long-term treatment with zidovudine (ZDV).

Two HIV-1 isolates were obtained from a patient receiving long-term treatment with zidovudine (ZDV). The in vitro sensitivity to ZDV triphosphate of the reverse transcriptase (RT) from both isolates appeared to be unchanged compared to that of the LAV-Bru HIV-1 reference strain. When isolates were grown in CEM cells (a T-lymphoblastoid tumor cell line) and their RT activity and core antigen (p24) production were determined, the level of p24 production compared to RT activity was high; in infected CEM cells treated with ZDV, RT activity was at background level while the p24 production was still significant, thus indicating a dissociation of RT activity and core antigen production.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

HIV1 quantitation in infected patients: a comparison of cell viraemia, plasma viraemia and R-HEV.

Anti-HIV1 trials require sensitive, reproducible and reliable parameters which measure virus load and virus production. The aim of the present study of 14 patients at different CDC stages was to compare results provided by three techniques which evaluate, respectively, cell-associated HIV1 infectivity (cell viraemia), plasma-associated HIV1 infectivity (plasma viraemia) and radiation-resistant expression ex vivo (R-HEV). For each patient, TCD4 lymphocytes were numbered and an HIV1 antigenaemia determination was carried out. We found no correlation between cellular viraemia and R-HEV; on the contrary, data concerning plasma viraemia and R-HEV were significantly correlated. While cellular viraemia and R-HEV were not correlated with TCD4 levels, plasma viraemia exhibited a significant negative correlation with TCD4 counts. Despite theoretical and practical differences, plasma viraemia and R-HEV may measure events in the viral replication cycle which bear a close resemblance; however, as designed, R-HEV seems to be far less discriminative than plasma viraemia.

CD4-Positive T-Lymphocytes↗
PubMedDate not supplied

Acquired immunodeficiency syndrome-associated Kaposi's sarcoma and human herpesvirus 8 DNA detection in serial peripheral blood mononuclear cell samples.

Human herpesvirus 8 (HHV8) DNA was amplified from peripheral blood mononuclear cells (PBMCs) using PCR in 120 HIV-seropositive in- and outpatients who were enrolled in a cohort study between January 1994 and June 1995. Risk factors for HIV infection were homosexuality/bisexuality alone in 64 cases (30 with Kaposi's sarcoma (KS) and 34 without KS, 4 of whom had KS lesions that appeared during follow-up in the cohort), heterosexual contact alone in 32 cases (among whom 1 woman with KS who was the spouse of a bisexual with KS), and transfusion of blood or blood products alone in 24 cases. Three blood samples at 3-4-month intervals were scheduled for each patient. Twenty-five HIV1-seronegative patients served as controls. A total of 47.1% of homo- or bisexual males with KS and 26.7% of homo- or bisexual males without KS had positive HHV8 DNA detection as compared with 21.9% of patients contaminated by heterosexual contact, 8.3% of blood product recipients and 0% of controls. HHV8 DNA detection was intermittent in all but 3 patients according to sequential sampling. Multivariate analysis showed that AIDS-KS was associated with sexual transmission, mainly homo- or bisexual practices and with HHV8 infection assessed by PCR in PBMCs.

Adult↗
PubMedDate not supplied

Asymmetric periflexural exanthem of childhood: microbiologic case-control study.

Our objective was to study possible etiologic factors of asymmetric periflexural exanthem of childhood (APEC) among a large panel of microbiologic agents not yet investigated. To do so, we designed a prospective case-control study using throat, stool, blood, and skin samples, and enlisted 37 children with APEC and 37 age-matched controls without eruption seen consecutively from February 1995 to April 1996 from a mixed referral center and community-based population. No interventions were done. Used as the main outcome measure was the differences in the two groups for microbiologic investigations. No significant statistical differences between cases and controls for virus and bacteria investigated were found. No microorganism was identified as a possible etiologic agent in any of the APEC patients. APEC is not a nonspecific cutaneous eruptive pattern to several common microbiologic agents. More sophisticated molecular approaches are needed to address its etiology.

Blood↗