Search PubMed⌕ Search

Biomedical subjects

F Lunel

Publications and source records attributed to F Lunel.

At least 55 records · Page 3Linked to original sources
PubMed1996

Antibody responses to hepatitis C envelope proteins in patients with acute or chronic hepatitis C.

Antibody responses to the hepatitis C virus (HCV) envelope proteins E1 and E2 were analyzed using two original assays in sera from 86 patients in different stages of disease. A Western blot assay and an immunofluorescence assay (IFA) were developed using envelope proteins produced, respectively, in Escherichia coli and in CV1 cells infected with a recombinant SV40. As a third method, the INNO-LIA HCV Ab III assay including E2 synthetic peptides was used. Of 38 chronically infected patients positive for anti-E2 antibodies by IFA, 26 were positive in the Western blot assay (68%) and 25 in the INNO-LIA test (66%). Thus, the detection of anti-envelope antibodies is highly dependent on the antigen formulation, and a native glycosylated form of the proteins is probably needed for their efficient detection. This study shows that the antibody response to HCV envelope proteins depends on the phase of infection. A few acutely infected patients displayed a response to E1 or E2 (36% by Western blot, 7% by IFA), and these antibodies seem to develop in patients evolving toward chronicity. The high prevalence in chronically infected subjects (62% to E2 by Western blot, 90% by IFA), particularly in subjects with essential mixed cryoglobulinemia (68% and 100%), confirms that the resolution of infection involves more than these antibodies. The antienvelope response in patients treated with interferon was investigated, but no significant relationship was found between antibody level prior to treatment and the evolution of hepatitis. The detection of anti-envelope antibodies, therefore, is not predictive of the response to antiviral therapy.

Acute Disease↗
PubMed1996

Hepatitis C virus genotypes and subtypes in patients with hepatitis C, with and without cryoglobulinemia.

BACKGROUND/AIMS: Recent reports have shown a high frequency of anti-hepatitis C virus antibodies in patients with cryoglobulinemia. The factors involved in the production of cryoglobulins in hepatitis C virus-infected patients are unknown. To assess the role of hepatitis C virus genotypes in the pathogenesis of mixed cryoglobulinemia, we analyzed their prevalence in a group of 118 hepatitis C virus-infected patients according to the presence or absence of cryoglobulins. METHODS: The hepatitis C virus genome was typed using the Line Probe Assay (LiPA, Innogenetics), for the most common genotypes (1a, 1b, 2a, 2b, 3, 4 or 5). RESULTS: Cryoglobulinemia was diagnosed in 60 (51%) patients, 33 (55%) of whom had type II and 27 (45%) type III cryoglobulins. Forty-four (37%) patients had no cryoglobulinemia and 14 (12%) patients had transient cryoglobulins. Cryoglobulins were significantly less prevalent in patients infected by genotype 1a. We found no statistical link between the hepatitis C virus genotype and the presence of symptomatic cryoglobulinemia, or the hepatitis C virus genotype and the type (II or III) of cryoglobulin. Interestingly, all six patients infected by hepatitis C virus genotype 4 or 5 had cryoglobulins. CONCLUSIONS: In patients with hepatitis C virus infection, cryoglobulinemia is not strongly associated with a particular HCV genotype or subtype. The mechanism by which cryoglobulins are produced remains to be elucidated.

Adult↗
PubMed1996

[Proposals for a strategy for evaluation and utilization of screening tests for hepatitis C].

New assays for the screening of anti-HCV antibodies are regularly proposed for registration. The evaluation of new tests is based on the measurement of their intrinsic value: sensitivity and specificity. To assess the sensitivity of a test, it is very important to be able to obtain sera samplets tested with a "Gold Standard", which is, for HCV, RNA detection. Sensitivity is defined as the ratio of the number of true positive to the number of true positive added to the number of false negative samples. The problem is to define the samples to be tested. It is methodologically impossible to use a serological test for samples selection. The Gold Standard might be performed on samples from the general population or more easily from risk groups. The estimation of the precocity is more difficult. The constitution of an acute hepatitis panel is of interest an the follow up of risk groups has to be encouraged. The estimation of the number of samples needed depends on the required precision in the sensitivity measurement. The confidence interval (CI) decreases when the number of samples tested increases and when the sensitivity is high. The important questions are opposite: if the test is positive what is the probability for the patient to be really positive? (positive predictive value PPV), and, if the test is negative, what is the probability for the patient to be non-infected? (negative predictive value: NPV). The NPV depends on the prevalence of HCV infection in the tested population and on the sensitivity of the test. PPV increases with the prevalence rate and the specificity. Regarding these results, one may suggest that donor screening assays and tests used for diagnose HCV infection in patients may be evaluated with different strategies. Regarding blood donors screening, sensitivity is the most important parameter, the best strategy is to eliminate risk groups, and then, to perform very sensitive assays on negative samples. On the other hand, for patients diagnosis, specificity (avoid false positive results) is more important. The best strategy is to select patients at risk from clinical findings and then, to perform a specific test. Screening strategies for the general population have to take into account these two different strategies.

Blood Banks↗
PubMed1996

Hepatitis C virus (HCV) genotype analysis in apparently healthy anti-HCV-positive Parisian blood donors.

BACKGROUND: As only a few studies have examined the prevalence of various hepatitis C virus (HCV) subtypes in blood donors, information about the variability and route of infection in apparently healthy persons is limited. STUDY DESIGN AND METHODS: Blood donations collected at a large Parisian hospital (52,441) were investigated for antibodies to HCV. Serum samples were screened with an enzyme immunoassay. All HCV-positive donations were retested with a second enzyme immunoassay and confirmed by immunoblot. The HCV genotype was determined for all polymerase chain reaction-positive subjects. Untypable genotypes were sequenced in the NS5B region. RESULTS: In total, 83 (0.26%) blood donors were anti-HCV positive. Men (0.34%) were significantly more likely to be infected (p < 0.001) than women (0.19%). Prevalence rates in men between 20 and 39 years of age were higher than those in similar women (p = 0.01), but greater in women aged from 50 to 65 years (p = 0.05). Fifty-five sera were viremic, of which 49 could be genotyped by a line probe assay. One new HCV type 1 subtype and three new HCV type 2 subtypes were discovered. In total, 28, 10, 11, 5, and 1 serum samples were grouped into HCV types 1 through 5, respectively, involving a total of 13 subtypes. The mean age of HCV type 2-infected donors was 42 +/- 11 years, but that for type 3-infected subjects was only 30 +/- 4 years (p = 0.0048). Forty-nine subjects showed elevated alanine aminotransferase levels; 39 (80%) of these subjects were viremic (p < 0.05). CONCLUSION: Among the sampled population, an HCV prevalence rate of 0.26 percent was found, with the five most common European genotypes causing the infections. Four new subtypes were discovered. Correlation between genotype and risk factors was not apparent, but links with age, sex, and ethnic origin emerged.

Adult↗
PubMed1996

Cyclosporin A-mediated cholestasis in patients with chronic hepatitis after heart transplantation.

Viral chronic hepatitis often occurs in heart transplant recipients receiving cyclosporin. This essential immunosuppressive drug may induce cholestasis. We investigated the effect of treatment with cyclosporin on serum conjugated bile acids in patients with chronic hepatitis developing after heart transplantation. Fifty-nine patients were studied: 17 with chronic hepatitis, 15 heart transplant patients with normal alanine aminotransferase activity, and 27 heart transplant patients with chronic hepatitis, the last two groups receiving cyclosporin. Hepatic biochemical tests and total bile acid concentration were determined on fasting blood samples. The individual glyco- and tauroconjugated bile acids were quantified by high-performance liquid chromatography and direct spectrometry. In patients taking cyclosporin the bilirubin concentration and the alkaline phosphatase activity were increased only when hepatitis was present, in association with a slight increase in cholic acid level (5.13 microM vs. 0.68 microM; P < 0.01). Conjugated lithocholate concentration was dramatically higher when hepatitis and immunosuppression with cyclosporin were associated (1.17 microM vs. 0.03 and 0.04 microM; P < 0.01). Chenodeoxycholate was the main circulating bile acid only in the heart transplant patients treated with cyclosporin but without hepatitis. These results suggest that the mechanisms which explain the cyclosporin-associated modifications of the bile acid pool are different according to the presence or absence of hepatitis. The occurrence of hepatitis in patients on cyclosporin led to an increase in serum lithocholate and primary bile acid concentrations. Further studies are required to assess the effect of ursodeoxycholic acid for this cholestasis.

Adult↗
PubMed1996

Long-term effects of interferon-alpha in five HIV-positive patients with chronic hepatitis B.

Chronic hepatitis B viral infection is common in human immunodeficiency virus (HIV) carriers, but the effectiveness of interferon therapy is still unknown. We report the results of a long-term pilot study of five patients, who were infected with HIV and chronic hepatitis B, treated by interferon. Five males co-infected with HIV and hepatitis B virus (HBV) (mean age 27 years) were given a 6-month course of interferon (IFN)-alpha 2b 5 million units (MU) three times weekly. On initiating the treatment, their CD4 lymphocyte count was 340-553 mm-3, their CDC stage was IIa-III; all had histologically proven chronic hepatitis, with Knodell's score ranging from 6-10, and active HBV replication (HBV DNA and hepatitis B e antigen (HBeAg) were detectable). There was no associated hepatitis delta virus (H delta V) or hepatitis C virus (HCV) infection. Follow-up was for 53 months on average (24-74 months). After the treatment, hepatitis B e antibody (HBeAb) and hepatitis B s antibody (HBsAb) seroconversion was observed in one patient, HBeAb seroconversion alone in two patients, HBV DNA was absent from serum in three patients, and HBV DNA significantly decreased in one patient. The serum alanine aminotransferase (ALT) activity was normal in four patients. Histological improvement was obtained in four patients. The HIV stage remained unchanged in all patients during the whole follow-up. These preliminary results suggest that interferon can be successfully used in immunocompetent HIV carriers with chronic hepatitis B as well as in HIV-negative patients.

Acyclovir↗
PubMed1996

Novel DNA assay for cytomegalovirus detection: comparison with conventional culture and pp65 antigenemia assay.

We compared conventional cytomegalovirus (CMV) isolation, rapid viral culture, a CMV pp65 antigenemia assay, and a novel CMV DNA hybrid capture system (HCS). A total of 309 blood samples from individuals in different risk groups were assessed by at least two of the methods mentioned above. Leukocytes were recovered either after centrifugation in Leucosep tubes containing 1.080 Ficoll for pp65 assay or after simple differential lysis steps for DNA detection. HCS was based on DNA hybridization with a CMV RNA probe and its capture by antibodies to DNA-RNA hybrids. The CMV pp65 lower matrix protein was detected by fluorescence with c10-c11 monoclonal antibody in formalin-fixed leukocytes. Concordant results were observed for 92.9, 78.3, and 82.7% of the patients when comparing (i) viral culture and the pp65 antigenemia assay, (ii) viral culture and HCS, and (iii) the pp65 antigenemia assay and HCS, respectively. Discordant results were observed between a positive HCS result and negative culture and/or pp65 results. These results were associated with relatively low DNA levels (< 20 pg/10(6) cells) and positive viruria. In conclusion, the pp65 antigenemia assay is a rapid and reliable method of detecting CMV and is preferable to culture, but the Murex HCS appears to be more sensitive for CMV detection.

Antigens, Viral↗
PubMed1995

Mechanisms underlying the monocyte-mediated antibody-dependent killing of Plasmodium falciparum asexual blood stages.

The relevance of the antibody-dependent cellular inhibition (ADCI) of Plasmodium falciparum to clinical protection has been previously established by in vitro studies of material obtained during passive transfer of protection by immunoglobulin G in humans. We here report further in vitro investigations aimed at elucidating the mechanisms underlying this ADCI effect. Results obtained so far suggest that (a) merozoite uptake by monocytes (MN) as well as by polymorphonuclear cells has little influence on the course of parasitemia; (b) the ADCI effect is mediated by a soluble factor released by MN; (c) this or these factors are able to block the division of surrounding intraerythrocytic parasites at the one nucleus stage; (d) the critical triggering antigen(s) targeted by effective Abs would appear to be associated with the surface of merozoites, as opposed to that of infected red blood cells; (e) the MN receptor for Abs effective in ADCI is apparently Fc gamma RII, and not RI; (f) MN function is up- and down-regulated by interferon-gamma and interleukin 4, respectively; and (g) of several potential mediators released by MN, only tumor necrosis factor (TNF) proved of relevance. The involvement of TNF in defense may explain the recently described increased frequency of the TNF-2 high-expression promoter in individuals living in endemic regions despite its compromising role in severe malaria.

Animals↗
PubMed1995

Essential mixed cryoglobulinemia. A comparative study of dermatologic manifestations in patients infected or noninfected with hepatitis C virus.

BACKGROUND AND DESIGN: An association between essential mixed cryoglobulinemia and hepatitis C virus (HCV) infection has been reported. Dermatologic manifestations are a classic presenting complaint in essential mixed cryoglobulinemia. The aim of this study was to compare the frequency and the nature of dermatologic manifestations in essential mixed cryoglobulinemia according to the presence of anti-HCV antibodies. Sixty-two consecutive patients with essential mixed cryoglobulinemia were tested for anti-HCV antibodies. Dermatologic manifestations were systematically assessed. RESULTS: Anti-HCV antibodies were detected in 35 patients. Palpable purpura corresponding histologically to leukocytoclastic vasculitis was the more frequently observed dermatologic manifestation and occurred mainly in HCV-antibody-positive patients. The patients with purpura had significantly higher serum cryoglobulin levels than patients without purpura. CONCLUSIONS: The frequency of palpable purpura is higher in HCV-antibody-positive patients and is related to the serum cryoglobulin levels.

Cryoglobulinemia↗
PubMed1995

HCV infection in a rural population of the Central African Republic (CAR): evidence for three additional subtypes of genotype 4.

The prevalence of hepatitis C virus (HCV) antibodies, HCV infection, and genotypes was studied in a rural population of the Central African Republic. In five villages, blood samples were taken from all the inhabitants present during the survey, belonging to Pygmies (299) and to Bantu and Banda ethnic groups (247). Using a second-generation ELISA screening and confirmation by immunoblot assay for the detection of HCV antibodies, all the Pygmies were negative, whereas seven Bantus/Bandas, aged > 35 years and with no familial relationship, were positive, giving a prevalence of 2.8% in this ethnic group. Five samples were also PCR positive; all belonged to genotype 4, but with three new subtypes identified by phylogenic analysis. These results indicate the co-existence of different HCV subtypes and raise questions about the natural transmission of HCV in this secluded population.

Adolescent↗
PubMed1995

Comparative study of conventional and novel strategies for the detection of hepatitis C virus RNA in serum: amplicor, branched-DNA, NASBA and in-house PCR.

The aim of this study was to compare the sensitivity and specificity of conventional procedures (in-house one-stage polymerase chain reaction (PCR) and in-house nested PCR) and of new technologies (rTth DNA polymerase (Amplicor), branched-DNA, NASBA (nucleic acid amplification system)) for the qualitative detection of hepatitis C virus (HCV) RNA in serum of HCV-infected individuals. Serum samples from 37 anti-HCV-positive individuals (15 with a normal alanine aminotransferase (ALT) level, 22 with an elevated ALT level) and 10 anti-HCV-negative individuals as negative controls were studied. A second panel, including 9 diluted serum samples (from 1/10 to 1/100,000) was constituted to establish the differences of sensitivity of the 5 procedures with small quantities of HCV RNA in the serum. The anti-HCV-positive individuals with elevated ALT gave positive results with all 5 procedures. In patients with a normal ALT level, the assays with the highest sensitivity were Amplicor, NASBA and nested RT-PCR, followed by one-stage RT-PCR, then branched-DNA. One false-positive result was observed with Amplicor, and two with in-house nested PCR. On diluted samples, Amplicor, NASBA and nested PCR appeared more sensitive than one-stage PCR and branched-DNA. It is concluded that new procedures have satisfactory sensitivity and specificity and could advantageously replace the conventional PCR procedures for the routine qualitative detection of serum HCV RNA.

Base Sequence↗
PubMed1995

Hepatitis C virus genotyping by means of 5'-UR/core line probe assays and molecular analysis of untypeable samples.

To test the theoretical possibility of 5'-UR mistyping between hepatitis C virus subtypes 1a and 1b, we combined a 5'-UR/Core line probe assay (LiPA) with a nested PCR system and retested 183 sera, previously genotyped as type 1a or 1b and originating mainly from Western Europe. Eight percent of these were found to be wrongly subtyped. Based on this method, 3 additional subtypes of type 1 were discovered (1d-1f). Randomly selected European type 2 sera (n = 18) were tested with a similar type 2 5'-UR/Core LiPA. They were unexpectedly found to belong to subtype 2c in the majority of cases. Among serum samples originating from South-East Asia, several additional genotypes (7a, 7c, 7d, and 9a) were detected which had 5'-UR sequence motifs indistinguishable from genotype 1. Based on 13,203 pairwise comparisons in the 340-bp NS5B region, classification into types, subtypes, and isolates was obtained in 99.8% of all cases by using the phylogenetic border value of 0.328 for subtypes/types and 0.127 for isolates/subtypes; and evidence for a 10th major type of HCV was provided. Combination of all available HCV sequence data from the 447-bp Core/E1 region and the NS5B 340-bp and 222-bp regions provided evidence for the existence of 10 types, including 50 subtypes. Previously, extensive studies involving genotypes 1a, 1b, 2a, and 2b indicated the importance of HCV subtyping in interferon treatment and progression of chronic liver disease. The herein described expansion in the number of HCV types and subtypes should help improve diagnosis, treatment and possibly prophylaxis of hepatitis C liver disease.

Base Sequence↗
PubMed1995

A comparative evaluation of the sensitivity of seven anti-hepatitis C virus screening tests.

The sensitivity of the most recent generation of anti-hepatitis C virus (anti-HCV) screening tests from seven manufacturers was evaluated with a common panel of 530 specimens from 320 HCV-infected subjects. This panel included 221 samples from 57 seroconverters (53 pre-sero conversion negative specimens and 168 positive samples) and 309 selected specimens from 263 other HCV-infected patients of which 19% exhibited NS3 or core reactivity alone with the presence of HCV-RNA assessed by PCR. None of the seven screening tests detected all infectious and antibody-positive specimens. However, important differences were observed between these assays in the number of false-negative results, which seemed mainly due to nonreactivity of antibody to the NS3 antigen.

Antigen-Antibody Reactions↗