PubMed Health⌕ Search

Biomedical subjects

C Buffet-Janvresse

Publications and source records attributed to C Buffet-Janvresse.

15 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↗
PubMed1987

Rapid decrease in the levels of the double-stranded RNA-dependent protein kinase during virus infections.

The double-stranded RNA-dependent protein kinase from human cells is a 68,000 molecular weight protein (p68 kinase), the level of which is enhanced significantly in cells treated with interferon. With a monoclonal antibody specific for p68 kinase, here we show the phosphorylation and steady-state levels of p68 kinase during virus infection. The p68 kinase is phosphorylated in interferon-treated cells during infection with encephalomyocarditis virus (EMCV), vesicular stomatitis virus (VSV), and vaccinia virus, thus indicating activation of p68 kinase during these virus infections, an essential step required for autophosphorylation of p68 kinase. However, in spite of this activation, the level of p68 kinase is rapidly decreased in virus-infected cells. The half-life of p68 kinase in uninfected cells is 6 to 7 hr, whereas in EMCV-infected cells it is 2 to 3 hr. This decrease in the level of p68 kinase is dependent on the multiplicity of virus infection and it seems to be specific since other cellular proteins as well as the activity of 2'-5'-oligoadenylate synthetase are not modified. Decreased levels of p68 kinase are also observed in cells infected with VSV and vaccinia virus. In the absence of virus infection, decreased levels of p68 kinase occur in cells following incubation with poly(I).poly(C).

2',5'-Oligoadenylate Synthetase↗
PubMed1987

[Mycoplasmas and pregnancy].

The pathogenic role of mycoplasms during pregnancy remains quite controverted, depending on the studies; for some it has an incidence on prematurity, delayed growth in utero and premature rupture of the membranes. The purpose of this study was, from a population of patients with term delivery, without any specific pathology, to verify the frequency of mothers carrying Mycoplasma Hominis or ureaplasma, and to determine the possible consequences on the newborn. A linear analysis of the evolution of the samples between D0 and D6 in the mother and the new born, shows that the presence of mycoplasms in the genital passages is as frequent in this non-risk population, and that the child may be contaminated about every other time; but this contamination appears to be very transient and without any consequences on the immediate neo-natal pathology. Systematic screening of genital mycoplasms in pregnant women does not permit, therefore, to select a group of exposed patients. In newborns who are contaminated, the risk of infection appears to be very low, but it would perhaps be desirable to study the long range future evolution of healthy carriers.

Female↗
PubMed1986

Enhanced level of double-stranded RNA-dependent protein kinase in peripheral blood mononuclear cells of patients with viral infections.

The protein kinase activity dependent on double-stranded RNA was assayed in extracts of peripheral blood mononuclear (PBM) cells from healthy volunteers and in patients with different types of virus infections. The protein kinase was assayed after one-step purification on an immunoaffinity column containing monoclonal antibody against the 68,000 Mr protein, a subunit of the protein kinase. In healthy individuals, the activity of the protein kinase remains constant. In contrast, the activity of the protein kinase is enhanced significantly in patients with viral infections and is decreased during the course of the disease in parallel with clinical ameliorations and reversal of clinical symptoms. There is a strong correlation between the enhanced levels of the protein kinase activity and another interferon-mediated enzyme, 2-5A synthetase. Both of these enzymes, therefore, could be used as markers to evaluate the state of the disease and recovery. In the different populations of lymphocytes, most of the protein kinase activity was found to be present in T and B lymphocytes, T lymphocytes showing a higher activity than B lymphocytes.

2',5'-Oligoadenylate Synthetase↗
PubMed1985

Enhancement of natural killer cell activity and 2-5A synthetase in operable breast cancer patients treated with polyadenylic; polyuridylic acid.

Treatment of operable breast cancer patients with a single injection of 60 mg poly(A); poly(U) (polyadenylic, polyuridylic acid) resulted in an enhancement of natural killer (NK) cell cytotoxicity against human myeloid K562 target cells. Furthermore, the level of 2-5A synthetase in peripheral blood lymphocytes of such patients was increased after the treatment. Both of these effects, measured 24 and 48 hours after the injection of poly(A); poly(U), were statistically significant compared to their respective levels before the treatment. These events, therefore, may be used as markers to monitor the immediate response of patients toward treatment with this synthetic double-stranded RNA.

2',5'-Oligoadenylate Synthetase↗
PubMed1985

Continuous production of interferon in normal mice: effect of anti-interferon globulin, sex, age, strain and environment on the levels of 2-5A synthetase and p67K kinase.

Two interferon-mediated enzymes, a 2-5A synthetase and a kinase that phosphorylates a 67 000 mol. wt. (p67K) protein were found at variable levels in different organs of mice. Among the different strains of mice included in this study, germ-free mice had the lowest levels of these enzymes. The levels of 2-5A synthetase and p67K kinase were enhanced significantly in all mice following treatment with mouse (alpha + beta) interferon. Here, we show that the presence of 2-5A synthetase and p67K kinase in different organs of normal mice (untreated) was due, at least in part, to a constant production of interferon under different physiological conditions. Accordingly, injection of normal mice with anti-mouse interferon (alpha + beta) globulin led to a significant decrease in the level of 2-5A synthetase and p67K kinase. In conventional mice (C3H/He), the level of both of these enzymes was higher in female than in male animals and was decreased with age or when such animals were reared isolated in a pathogen-free protected unit. The levels of 2-5A synthetase and p67K kinase were also decreased in normal mice following injection with a powerful antibiotic against a very wide spectrum of Gram-positive and Gram-negative bacteria. These results suggest that the production of interferon was induced continuously in normal mice. Such induction was mediated by both internal and external agents.

2',5'-Oligoadenylate Synthetase↗
PubMed1984

Enzyme markers for the presence of circulating interferon: 2-5A synthetase in blood lymphocytes and protein kinase in platelet-rich plasma.

The level of 2-5A synthetase in extracts of peripheral blood lymphocytes and a specific protein kinase activity in platelet-rich plasma were measured in normal individuals and in patients suffering from viral or bacterial infections. The level of these enzymes was tested at different times during the disease. The level of 2-5A synthetase and the protein kinase activity was enhanced by several-fold during viral and bacterial infections and decreased during the course of the disease in parallel with clinical ameliorations and reversal of clinical symptoms. Among the different types of infections studied, higher levels of these enzymes were observed during viral than bacterial infections. Our results emphasize the use of these enzymes as markers to evaluate the state of the disease and recovery. Furthermore, they provide evidence for the production of interferon during different types of infection.

2',5'-Oligoadenylate Synthetase↗
PubMed1982

Plasma protein kinase activity enhanced by interferon is found in platelets.

A protein kinase activity analogous to that found in interferon-treated HeLa cells is detectable in human plasma rich in platelets. This kinase activity is manifested by the phosphorylation of an endogenous Mr 72000 protein which could be conveniently assayed after partial purification on poly(G)-Sepharose. Here, we show that the protein kinase system in the plasma consists of at least 2 components. The protein kinase is found to be localised in the platelets whereas most of the substrate (the Mr 72000 protein) is found free in the plasma and a fraction of it associated with the surface of platelets.

Blood Platelets↗
PubMedDate not supplied

Assay and the levels of 2-5A-synthetase in lymphocytes of patients with viral, bacterial and autoimmune diseases.

The level of 2-5A-synthetase in extracts of peripheral blood lymphocytes was estimated by the capacity of the enzyme to synthesize 2-5A in the presence of ATP. The 2-5A was then purified on a small column of DEAE-cellulose. Here we show that under or experimental conditions, the amount of 2-5A formed is proportional to the level of the enzyme. The concentration of 2-5A (nmol of AMP/10(6) lymphocytes) in an assay therefore reflects the level of the enzyme. Enhanced levels of 2-5A synthetase were observed in the lymphocytes of patients with viral and bacterial infections. In most of the cases studied, these enhanced levels of the enzyme decreased during the course of infection parallel to recovery. Thus, the level of 2-5A synthetase may indicate the state of the disease and its evolution during the period of treatment; furthermore, it may be a useful marker in monitoring the return to a normal physiological condition. In addition to patients with viral and bacterial infections, enhanced levels of 2-5A synthetase were observed in patients suffering from autoimmune diseases. In five patients studied here, the enhanced levels of 2-5A synthetase remained high at different periods during the course of the disease. These results suggest the presence of circulating interferon throughout the disease.

2',5'-Oligoadenylate Synthetase↗