Search PubMed⌕ Search

Biomedical subjects

J Pillot

Publications and source records attributed to J Pillot.

At least 19 recordsLinked to original sources
PubMed1992

Anti-pre-S responses and viral clearance in chronic hepatitis B virus infection.

Serial sera were collected prospectively during the clinical course of 13 HBsAg carriers with chronic liver disease and analyzed for ALT levels, pre-S1 and pre-S2 antigens and corresponding antibodies and other serological hepatitis B virus markers. In five patients, anti-pre-S1 and anti-pre-S2 antibodies became detectable in multiple serum samples, whereas in eight patients anti-pre-S was never detected or only appeared transiently during the follow-up. The first pattern was associated with normalization of ALT levels and undetectable pre-S antigens and viral DNA by the polymerase chain reaction assay at final follow-up. HBsAg clearance occurred in two of the five patients. The second pattern was one of persistence of HBsAg and pre-S antigens, associated with the presence of serum HBV DNA detectable by spot hybridization or polymerase chain reaction regardless of clinical outcome. These findings demonstrate the occurrence of anti-pre-S antibodies in chronic hepatitis B virus-induced liver disease and associate anti-pre-S appearance with the clearance of hepatitis B virus from serum.

Adult↗
PubMed1992

HBsAg in urine: a new approach for the detection of urinary antigens.

In order to define the optimal conditions for detection of microbial antigens in urine, urinary HBsAg excreted during hepatitis B was chosen as a model. Using commercial kits, which mainly involve anti-discontinuous epitopes, we found urinary HBsAg in only 50% of patients with HBsAg in their sera. In contrast, with an inhibition method involving a monoclonal antibody recognizing a continuous epitope, urinary HBsAg was found in 100% of these patients. Structural analysis of HBsAg showed that urinary HBsAg is denatured; it can escape detection by commercial kits well fitted for detection of native serum HBsAg. General implications for the revelation of urinary microbial antigens are discussed.

Antibodies, Monoclonal↗
PubMed1992

Detection of hepatitis C virus sequences in sera with controversial serology by nested polymerase chain reaction.

The specificity of first-generation enzyme-linked immunosorbent assays (ELIAs) for antibody detection in individuals with hepatitis C virus (HCV) infection has been questioned in some pathological situations. We observed a surprisingly high prevalence of anti-HCV antibodies in alcoholic patients, and thus, false-positive reactions in anti-HCV tests were strongly suspected. The introduction of new epitopes, particularly a core protein, C22 (second-generation tests), seems to increase the sensitivity of anti-HCV detection. In order to study the specificity of the second-generation tests, 60 serum samples from alcoholic patients found to be positive by the first-generation anti-HCV ELISA (Ortho) were reexamined by a second-generation anti-HCV enzyme immunoassay (Abbott) and a recombinant immunoblot assay (RIBA II; Chiron). Fifteen serum samples gave contradictory results when they were tested by the two assays. We performed nested polymerase chain reactions (PCRs) to confirm that the discrepancies that we observed could be due to the presence of low levels of anti-HCV antibodies, which were detected by a more sensitive test, or to unspecific positive reactions. Nested PCR revealed the presence of HCV RNA sequences in all anti-HCV-positive sera or sera that were weakly positive by ELISA. Anti-HCV positive by RIBA II was always correlated with the presence of viral RNA in serum, but HCV RNA was detected in RIBA II-negative sera. These results indicate that the specificity of the second-generation tests is an important improvement but that an HCV infection can still persist without detectable antibodies. PCR remains the reference assay to clear up controversial serology results and to detect HCV infection in patients with no anti-HCV-detectable immune response.

Base Sequence↗
PubMed1992

[Biological diagnosis of hepatitis e. Completion of a test for detection of infected patients].

The aim of this study is to set up a biological method for diagnosing hepatitis E using an immunoenzymatic technique. This technic attaches specific IgM of a monkey experimentally infected with the Hepatitis E virus to a solid phase. These antibodies capture the HEV antigen (AgHEV) present in the stools of patients with hepatitis E. Antigen was then revealed using purified and labelled IgG from the same monkey. Using this method, we were able to: prove the existence of sporadic cases of hepatitis E in Dakar, biologically confirm the diagnosis of hepatitis E in 53.33% of patients suffering from hepatitis during an epidemic in Constantine and in 26.3% of patients in Bangkok who contracted oral-fecal transmitted hepatitis. Confirmation by inhibition and control reactions demonstrated the specificity of this test and its usefulness as a tool for the biological diagnosis of hepatitis E.

Alanine Transaminase↗
PubMed1992

[Transmission of hepatitis B virus from mother to child in Bamako-Mali].

Results of a study about mother-infant transmission of hepatitis B virus (HBV) confirm the high degree of positivity of HBV markers in Bamako, Republic of Mali. Among 372 sera of mother-newborn pairs, seroprevalence of HBs Ag has been around 11% in mothers. The lack of anti HBc IgM in all sera agree probably with a relative old contamination. Pre-S2 epitope marker has been found in more than 70% of HBs Ag positive mothers and 50% of their children. Large discordance has been noted between the prevalence rate of this marker and the HBe Ag and viral DNA, other markers of HBV replication. Further studies are necessary for the clear understanding of HBV transmission systems in our country.

Adolescent↗
PubMed1991

Prognostic significance of pre-S2 antigen and antibody in fulminant hepatitis B. Evidence for heterogeneous serological responses.

Serial sera were collected prospectively and from early on in the clinical course of ten patients with fulminant hepatitis B. These were analysed for HBV DNA (dot-blot technique), HBsAg, HBeAg, pre-S2-Ag and their respective antibodies. Two patterns emerged in nine of the patients. The first and well-recognised pattern of rapid clearance of antigens and appearance of antibodies was seen in four patients, all of whom survived. The second pattern seen in five patients was one of persistence of HBsAg and pre-S2 antigen and failure to detect antibodies but only one patient survived. The first pattern may reflect a more rapid cessation of virus replication and this may favour liver cell regeneration and recovery. In contrast, the second pattern may indicate continuing virus replication and liver cell damage which could contribute to the high mortality in some patients with fulminant hepatitis B.

Adolescent↗
PubMed1991

Non-immune binding of human protein Fv to immunoglobulins from various mammalian and non-mammalian species.

Reactivity of the secretory protein Fv with immunoglobulins (Ig) from various species of vertebrates was investigated. Binding was observed throughout all taxonomic classes: mammalian, avian, reptilian, amphibian and fish. Contrasting with this wide spectrum, no significant binding was found with most mammalian ungulates, such as horse (Perissodactyl), cow, sheep and goat (Artiodactyls). Nevertheless, disruption of the hydrogen bonds of Ig allowed these non-reactive molecules to bind. Such a conserved reactivity during evolution, and our previous data on the effect of the cleavage of the intra-chain disulphide bonds, suggest that protein Fv recognizes a discontinuous framework structure involving both the FR1 and FR3 regions in the variable domain of the heavy chain of Ig.

Animals↗
PubMed1991

Non-immune VH-binding specificity of human protein Fv.

The specificity of human F(ab)-binding Protein Fv (previously called Protein F), a sialoprotein released into the digestive tract mainly during hepatitis, was investigated with fragments or chains of monoclonal immunoglobulins. Protein Fv bound an unreduced H-chain dimer of a monoclonal human IgA2m(1) molecule but neither the corresponding L-chain dimer, nor several Bence-Jones molecules. Using enzymatic subfragments of F(ab)mu, or F(ab')2 gamma, a significant binding was observed with Fv fragments (VH + VL), while Fb fragments (CH1 + CL) were inactive. Taken altogether, these results prove that the structure recognized by Protein Fv is located in the VH domain. This structure probably involves discontinuous epitopes linked by a disulphide bond, which are destroyed by combined reduction and dissociation. Protein Fv does not interfere with the antigen-binding site, since there was no reciprocal inhibition with the antigen-antibody reaction.

Chromatography, High Pressure Liquid↗
PubMed1991

Protection by human serum from the immunosuppression induced by spermine in vitro.

The in vitro suppressive activity of spermine to PHA-induced proliferation of human T lymphocytes is shown to be abolished by normal human serum. This protection acts within the first 4 hr of culture and is due to a protein of 67 kDa, showing an isoelectric charge of pH 4.9. This protein does not bind, or modify, spermine and does not inhibit spermine oxidase activity, an enzyme required for the in vitro suppression. Results with acrolein confirm that this eventual cleavage product is probably not involved in the spermine-induced suppression. Nevertheless, since serum also reduces acrolein-induced suppression, it is probable that both these protective mechanisms are related. Such a protection of T lymphocytes by a serum factor may play an important role by preventing diffusion, outside the genital tract area, of a potential spermine-induced immunosuppression.

Blood Physiological Phenomena↗
PubMed1991

Identification of a strong enhancer element upstream from the pregenomic RNA start site of the duck hepatitis B virus genome.

The genome of the duck hepatitis B virus (DHBV) contains an enhancer element. This sequence, of 192 bp, is located in the 3'-terminal coding region of the DNA polymerase gene (nucleotides 2159 to 2351), upstream from the pregenomic RNA start site. This enhancer potentiates a marked increased activity from the heterologous thymidine kinase promoter in an orientation-independent manner and at a proximal, as well as a distal, location. The DHBV enhancer activates transcription in a relatively cell-type-independent manner. Sequence homologies with the nuclear factor EF-C binding site are located in the DHBV enhancer. By using the HepG2 nuclear extracts and the DHBV enhancer as probes, a complex was observed in mobility shift assays.

Animals↗
PubMed1991

[High incidence of sporadic non-A, non-B hepatitis in Morocco: epidemiologic study].

Non-A, Non-B hepatitis and their sequelae seem to be as frequent as HBV infections in Morocco. These diseases represent an important problem of public health because their high incidence and high fatal rate. Some aspects of the epidemiology of Non-A, Non B acute hepatitis were evoking a high incidence of enterically transmitted hepatitis E. That was confirmed by serum studies having shown that hepatitis E antibodies were detected in more than 60% of patients with acute Non-A, Non-B hepatitis. However this type of hepatitis has been recognized only as sporadic (non-epidemic), mainly transmitted by personal contacts in low hygiene conditions. Other Non-A, Non-B acute hepatitis (around 35%) were certainly due to hepatitis C virus infection, because the presence of hepatitis C antibodies in the serum of the patients. However, in our study, hepatitis C seemed to be rarely transmitted by transfusion or other blood related route. Chronic liver diseases related to Non-A, Non-B virus infection appeared to be as frequent as the ones due to hepatitis B virus. Serological studies had shown that about seventy-four per cent of the studied cases were related to an infection by hepatitis C virus (presence of hepatitis C antibodies). Among other Non-A, Non-B chronic liver diseases the possible existence of some cases due to hepatitis E virus infection cannot be ruled out but this hypothesis needs further investigations to be verified. The prevalence of the markers of past hepatitis B infection in convalescent patients from Non-A, Non-B hepatitis is comparable to the prevalence of hepatitis B infection markers in blood donors. However, chronic HBV infection could be a factor facilitating the clinical expression of the Non-A, Non-B hepatitis.

Adolescent↗
PubMed1991

Independent risk factors for hepatocellular carcinoma in French drinkers.

The aim of this study was to assess whether markers of hepatitis B virus or hepatitis C virus infection are independent risk factors for hepatocellular carcinoma in drinkers after adjustment for three known risk factors: cirrhosis, age and male sex. Among 2,015 consecutive drinkers admitted, hepatitis C virus antibodies were found by sensitive radioimmunoassay in 1,259. The following five factors have been identified and ranked as risk factors for hepatocellular carcinoma in unidimensional and regression analysis: cirrhosis (p less than 0.001), age (p less than 0.001), male sex (p less than 0.001), presence of HBsAg (p less than 0.001) and presence of hepatitis C virus antibodies (p less than 0.03). Among drinkers with cirrhosis, the patients with hepatocellular carcinoma were older (64 +/- 11 yr vs. 56 +/- 9 yr; p less than 0.001), were more often male (93% vs. 65%; p less than 0.0001) and had higher prevalence of HBsAg (9% vs. 2%; p = 0.02) and hepatitis C virus antibodies (41% vs. 26%; p = 0.02). A simple algorithm permitted us to identify a high-risk population of drinkers: the male cirrhotic patient older than 50 yr. The relative risk of hepatocellular carcinoma in this selected population was 17.7 (95% confidence interval = 9.0 to 37.5; p less than 0.0001). From a pragmatic point of view, the detection of HBsAg or hepatitis C virus antibodies, although independently associated with hepatocellular carcinoma, is not useful in increasing the diagnostic value of this algorithm because of the poor sensitivity of these tests. The weak relationships observed between hepatitis C virus antibodies and hepatocellular carcinoma needs confirmation by more accurate tests.

Age Factors↗
PubMed1990

Protein F. A novel F(ab)-binding factor, present in normal liver, and largely released in the digestive tract during hepatitis.

Significant percentages of patients suffering from non-A non-B hepatitis (43%) and B hepatitis (35%) were found to release an Ig-binding factor in their stools. This factor, which we called "protein F" was less frequently observed (20%) in patients suffering from other liver disorders, and was found in only 6.7% of healthy subjects (p less than 10(-7), less than 10(-4), and less than 0.03, respectively). The specificity of the detection test (a nonimmune ELISA-like assay) was confirmed by inhibition experiments. Binding was located on the F(ab) fragment of Ig, irrespectively of their isotype. Protein F was inactivated by pepsin, neuraminidase, and high concentrations of subtilisin, whereas it was resistant to trypsin and chymotrypsin. Molecular sieving by HPLC indicated an apparent molecular mass of 175 kDa. In preparative SDS-PAGE, the molecular mass was 85 kDa in favor of a dimer disrupted under dissociating conditions. Preparative IEF showed the isoelectric charge to lie between 3.9 and 4.1. Analysis of liver extracts from two patients suffering fron non-A non-B hepatitis, and from a transplant donor, revealed the presence of the factor in the three cases.

Carrier Proteins↗
PubMed1990

A biphasic pattern of anti-pre-S responses in acute hepatitis B virus infection.

The clinical relevance of the immune response to the translation products of the pre-S1 and pre-S2 regions of hepatitis B virus was examined by testing sequential serum samples from 17 patients with acute self-limited hepatitis B and from two patients in whom chronic liver disease developed. Anti-pre-S antibodies were determined by enzyme immunoassays based on the inhibition of binding of monoclonal antibodies to epitopes in the pre-S1 and pre-S2 sequence. In acute, self-limited infection, anti-pre-S antibodies appeared in a biphasic pattern. The early antibodies were detected at the time of clinical signs of acute disease when HBsAg and often HBeAg were present, but hepatitis B virus DNA was no longer detectable in serum. Anti-pre-S levels then fell, but subsequently reappeared as the late antibody during the recovery phase, after development of anti-HBe, but before anti-HBs. Anti-pre-S responses were detected in 15 of 17 patients who recovered (88.2%) and in both patients with acute hepatitis B virus infection evolving to chronic liver disease. Although the early antibodies to pre-S1 and pre-S2 proteins appeared at the time of decreasing levels of infectious virus in serum in cases of self-limited infection, these antibodies also were transiently or continuously present with high levels of serum hepatitis B virus DNA in patients in whom chronic hepatitis B infection developed. Thus the anti-pre-S response in acute hepatitis is not a prognostic marker for clinical resolution.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗