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B Masquelier

Publications and source records attributed to B Masquelier.

5 recordsLinked to original sources
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↗