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Biomedical subjects

C Trepo

Publications and source records attributed to C Trepo.

At least 145 records · Page 8Linked to original sources
PubMed1994

Absence of p53 mutation at codon 249 in duck hepatocellular carcinomas from the high incidence area of Qidong (China).

Dietary aflatoxin and hepatitis B virus infection may play a role in generating the p53 tumor suppressor gene codon 249 hotspot mutation found in human hepatocellular carcinomas (HCCs) from Qidong (China) and southern Africa. No data are available on the HCC site-specific mutation of the p53 gene in hepadnavirus-infected animals exposed to AFB1. We have searched for the presence of p53 gene codon 249 mutations in both duck hepatitis B virus (DHBV) positive and negative HCCs of domestic ducks from Qidong, where the human p53 hotspot is so prevalent, as well as in duck HCCs experimentally induced by AFB1. Direct sequencing of DNA amplification products encompassing p53 codon 249 did not reveal any mutations in 11 HCCs from Qidong ducks, regardless of the status of DHBV infection. In addition no mutation was detected in four HCCs from AFB1-treated ducks. This contrasts with the human data; however, in humans, the mutation and the preferential binding of AFB1 to codon 249 occurs at the third nucleotide G, while in duck, the codon 249 lacks this G residue. The DNA sequence of adjacent codons is also different in the two species even though the amino acid sequence is identical. This may explain the low frequency of mutation we have observed. In addition, species differences in metabolism and DNA repair could influence the occurrence of codon 249 mutations.

Aflatoxin B1↗
PubMed1994

Paromomycin: an effective treatment for cryptosporidial diarrhea in patients with AIDS.

Cryptosporidiosis is a common cause of diarrhea in patients with AIDS but remains one of the most challenging AIDS-related conditions to treat. We therefore carried out an open, uncontrolled, prospective study to evaluate the efficacy of oral paromomycin for the treatment of chronic diarrhea due to Cryptosporidium in 24 successive patients infected with human immunodeficiency virus. Twenty-two of the 24 patients responded clinically, with complete remission occurring in 18 cases and marked reduction of the diarrhea occurring in four. Clearance of cryptosporidia from stools and/or intestinal biopsy specimens occurred within 2-4 weeks. Furthermore, all 18 patients who achieved complete remission gained weight. Ten patients relapsed either during administration of maintenance therapy or after discontinuation of treatment, but diarrhea resolved again after increasing or restarting paromomycin therapy in all but two. Paromomycin appeared to be an active and well-tolerated treatment for cryptosporidiosis in patients with AIDS. Efficacy is dose-related, and continuous maintenance therapy is required to prevent relapses. These data suggest that paromomycin might be given as first-line therapy in AIDS-related cryptosporidiosis, but this should be confirmed by the findings of a controlled, randomized trial.

AIDS-Related Opportunistic Infections↗
PubMed1994

Fulminant hepatitis with severe lactate acidosis in HIV-infected patients on didanosine therapy.

We report two cases of fulminant hepatic failure in HIV-1-infected patients treated with didanosine (ddI). Clinical manifestations including vomiting, diarrhoea and dyspnoea were identical in both cases. Biological data mainly revealed hepatic failure and lactic acidosis. Histological examination of liver biopsies showed diffuse microvesicular steatosis. The outcome was fatal in both patients. The only comparable case previously reported (Lai et al., 1991) showed close similarities in the clinical, biological and histological manifestations with microvesicular steatosis. This prompted us to suspect that ddI might be responsible for fulminant hepatitis in all three AIDS patients. This toxic effect may be added to the list of potential adverse events occurring during ddI therapy.

AIDS-Related Opportunistic Infections↗
PubMed1994

Influence of hepatic impairment on the pharmacokinetics of nefazodone and two of its metabolites after single and multiple oral doses.

The pharmacokinetics of nefazodone, a new antidepressant, and two of its active metabolites, hydroxy-nefazodone and m-chlorophenylpiperazine, were determined after single and repeated oral escalating doses of 50, 100 and 200 mg, in healthy volunteers (n = 13) and patients with mild (n = 13) or severe (n = 6) hepatic impairment. All subjects were classified according to their dextromethorphan oxidation capacity. In healthy volunteers, nefazodone was rapidly absorbed after which the plasma concentrations declined with an apparent elimination half-life ranging from 2.7 +/- 1.7 h to 10.2 +/- 4.4 h according to the dosage. Hydroxy-nefazodone appeared rapidly in plasma and its time-course (half-life ranging 1.4 +/- 0.9 h to 6.5 +/- 1.6 h) paralleled that of nefazodone, while mCPP showed low and variable concentrations. The disproportionately longer half-life and more markedly increased Cmax and AUC0-48 which was observed with dosage and treatment duration, and moreover AUC0-12 at steady state significantly higher (P < 0.05) than AUC0-infinity after single dose demonstrated the non-linearity of the pharmacokinetics of nefazodone and hydroxy-nefazodone. The constant molar AUC0-48 hydroxy-nefazodone/nefazodone ratio (0.32 +/- 0.04) and the close correlation (r2 = 0.95) between kinetic parameters of nefazodone and hydroxy-nefazodone suggest that nefazodone hydroxylation is not a saturable process. The kinetics of nefazodone and metabolites were significantly affected by severe but not by mild liver insufficiency. As a consequence, on a pharmacokinetic basis nefazodone should be used with caution in severely hepatic impaired patients.

Adolescent↗
PubMed1993

Characterization of minor and major antigenic regions within the hepatitis B virus nucleocapsid.

Hepatitis B core antibodies (anti-HBc) appear very early during the course of the hepatitis B virus infection and often persist years after viral clearance. In order to characterize the immunodominant domain of the HBcAg, the human immune response against the HBV nucleocapsid (HBcAg) was analyzed by using 14 synthetic peptides. Anti-HBc antibodies were detected by an indirect enzyme-linked immunosorbent assay (ELISA) with HBc peptides. Results suggest that the anti-HBc response is heterogeneous and directed against the whole primary structure of the HBc protein. Results also indicate that the epitopes recognized by anti-HBc antibodies can vary with the stages of the disease. In most sera from patients with serological evidence of acute HBV infection, anti-HBc antibodies recognized all the HBc peptides; conversely, after the acute phase, anti-HBc antibodies recognized predominantly epitopes located within the central region of the HBc protein from residue 74 to 123. Our results suggest that the HBV core protein is made up of two antigenic regions: a major one expressing a family of immunodominant epitopes from residue 74 to 123, whereas the minor encompasses the rest of the protein. The concept of the conformational nature of the unique HBcAg determinant is discussed, suggesting numerous families of linear epitopes.

Amino Acid Sequence↗
PubMed1993

Fine mapping of neutralization epitopes on duck hepatitis B virus (DHBV) pre-S protein using monoclonal antibodies and overlapping peptides.

To define the residues involved in duck hepatitis B virus (DHBV) neutralization at the amino acid level, we have used a procedure combining monoclonal antibodies (MAbs) and overlapping octapeptides (Pepscan). Two neutralizing MAbs (SD20 and 900), specific for the pre-S protein were shown to reduce DHBV infectivity in vivo by 75 and 90%, respectively, while complete protection of ducklings was achieved with a polyclonal antiserum raised against the bacterially expressed first 131 amino acids of the DHBV pre-S region (DHBpre-S). Using fusion polypeptides, the binding sites of these MAbs were localized between aa 77 and 100 on pre-S protein. We have used octapeptides spanning the pre-S sequence from aa 64 to 115 for fine mapping of these epitopes. Within the sequence scanned, the polyclonal anti-DHBpre-S antiserum recognized a region exclusively limited to the residues E82-K95, suggesting immunodominance of this region in the sequence aa 64-115. The epitope recognized by Mab 900 was mapped within the same region, whereas the epitope recognized by Mab SD20 was localized downstream from this region. To define the amino acids essential for binding to the highly neutralizing Mab 900, we have used single amino acid replacement and demonstrated that two residues Q87 and W88 were important for antibody recognition.

Amino Acid Sequence↗
PubMed1993

Duck hepatitis B virus infection, aflatoxin B1 and liver cancer in ducks.

The association between chronic infection by hepadnaviruses isolated from human (HBV), woodchuck (WHV), ground squirrel (GSHV) and development of hepatocellular carcinoma (HCC) in their respective hosts is well established (reviewed in [11, 15, 17]). By contrast, the association of duck hepatitis B virus (DHBV) infection with HCC is less documented. Pekin ducks congenitally infected with DHBV and followed for several years throughout the world do not develop liver tumors: HCC has been found only in domestic ducks from a single area of China, Qidong. Several factors such as DHBV carrier rate, breed and age of ducks, subtype of DHBV and environmental carcinogens are suspected to contribute to this striking difference between the geographical repartition of liver cancer in DHBV-carrier ducks. In this brief review we will consider successively the role of these different factors in duck liver oncogenesis.

Aflatoxin B1↗
PubMed1993

Cyclosporin A treatment in primary biliary cirrhosis: results of a long-term placebo controlled trial.

BACKGROUND: Effective treatment for primary biliary cirrhosis (PBC) resulting in slower progression and improved survival remains elusive. Cyclosporin A (CyA), which has been so effective in preventing human allograft rejection, has shown promise in small numbers of patients in early studies. METHODS: Three hundred forty-nine patients with PBC were randomized to receive CyA, 3 mg.kg-1.day-1, or placebo in a multicenter study with follow-up for 6 years. The end point was death or liver transplantation. RESULTS: Cox multivariate analysis showed time from entry to death or transplantation was significantly prolonged (by up to 50%) in the CyA-treated group. Liver-related mortality was also significantly lower. However, a univariate analysis of survival showed no statistical differences between the two groups. Biochemical liver indices deteriorated more slowly in the CyA-treated group, but serum creatinine concentration was elevated > 150 mumol/L in 9%, necessitating permanent discontinuation in half of these. A reduction in the dose of CyA was required in 11% because of hypertension. CONCLUSIONS: CyA has some therapeutic potential in primary biliary cirrhosis, providing blood pressure and renal function are closely monitored.

Adult↗
PubMed1993

Specific detection of anti-HBc antibodies with an enzyme immunoassay using recombinant HBcAg and monoclonal antibodies.

An enzyme immunoassay for the detection of total anti-HBc antibodies in undiluted serum samples was developed. This assay utilizes an anti-HBc monoclonal antibody and a recombinant HBc antigen. The results of the clinical validation are now reported. A total of 1,301 sera were tested using both the Recombinant TOTAL HBc Ab EIA and a reference assay. The specificity was evaluated on a panel of 573 normal human sera and human sera from subjects with pathological findings unrelated to a hepatitis B virus infection. The sensitivity was studied on a total of 455 sera from HBV infected patients at different stages of infection. The final results indicate 99.8% sensitivity and 99.8% specificity. In addition, 273 sera with either isolated anti-HBc antibodies or with anti-HCV antibodies were tested. The agreement between the Recombinant and the reference assay for these two populations, 96.6 and 90.1%, respectively, is discussed.

Acute Disease↗
PubMed1993

Assessment of screening tests for transfusion-associated non-A non-B hepatitis.

Non-A non-B hepatitis is the most common serious sequela of blood transfusion, and its screening has become an essential goal of blood transfusion centers. Before 1989, two surrogate screening tests (for alanine aminotransferase and for antibody to hepatitis B core antigen) were used; in 1989, a direct test for the antibody to hepatitis C virus (the main agent of this hepatitis) was developed. The French National Agency for the Development of Medical Evaluation undertook an investigation to determine the optimal prevention strategy for posttransfusion non-A and non-B hepatitis (PTH). A detailed literature review was performed, complemented by expert group opinion. The performance of each test was derived indirectly by calculating the number of cases of PTH averted by each test. Hepatitis C virus testing is probably the most promising strategy, but different policies can be developed given the uncertainties of scientific data. Cost considerations should be taken into account in identifying the best screening strategy.

Alanine Transaminase↗
PubMed1993

Monitoring of early events of experimental woodchuck hepatitis infection: studies of peripheral blood mononuclear cells by cytofluorometry and PCR.

The peripheral blood mononuclear cells (PBMC) of woodchucks experimentally infected by woodchuck hepatitis virus (WHV) were examined simultaneously for the presence of membrane associated WHV antigens by cytofluorometry, and for WHV DNA and RNA sequences by the polymerase chain reaction (PCR). Four woodchucks were inoculated: two with a well-defined infectious inoculum and two with an inoculum obtained from an animal at the late incubation phase, which was positive for WHV DNA by PCR but still devoid of WHV markers. Infection was demonstrated in all four inoculated woodchucks by the appearance at different times of WHV DNA and WHV antigens in both leucocytes and serum. WHV DNA was first detected by PCR either in the serum (two cases) or in leucocytes (two cases). The mean percentage of cells positive for membrane associated WHsAg or WHcAg detected by cytofluorometry were 37% +/- 25 and 17% +/- 15 respectively. After 8 weeks, all inoculated animals were WHsAg positive in serum. These data suggest that PBMC are involved in the early events of hepadnavirus infection. They also show that sera which are positive by PCR for WHV DNA may transmit viral infection even while still seronegative for WHV markers and for WHV DNA by dot blot.

Animals↗
PubMed1993

Diagnostic value of amplification of human cytomegalovirus DNA from gastrointestinal biopsies from human immunodeficiency virus-infected patients.

In order to assess the value of human cytomegalovirus (HCMV) DNA amplification of gastrointestinal biopsies, we studied 57 human immunodeficiency virus-infected patients with and without gastrointestinal HCMV diseases. After DNA extraction, a 406-bp fragment from the unique short region of the HCMV genome was amplified by 35 cycles of polymerase chain reaction (PCR) and semiquantified from 80 to 80,000 HCMV genomic copies. Among 12 non-AIDS patients, the PCR assay was negative for 11 of 12 duodenal and 8 of 8 colorectal samples. It was also negative for 28 of 31 duodenal and 12 of 15 colorectal samples from 31 AIDS patients without gastrointestinal HCMV diseases. Among 14 AIDS patients with gastrointestinal HCMV diseases, the PCR assay was positive for 12 of 12 patients with HCMV duodenitis and for 13 of 13 patients with HCMV colitis. Results were dichotomized between high and low HCMV-DNA copy numbers. For duodenitis, sensitivity was 92% and specificity was 100%. For colitis, sensitivity was 92% and specificity was 93%. Specificity and sensitivity were not influenced by shedding status for HCMV or by other gastrointestinal infections. HCMV DNA amplification of gastrointestinal biopsies is a sensitive and specific tool for the diagnosis of gastrointestinal HCMV diseases in AIDS patients.

AIDS-Related Opportunistic Infections↗
PubMed1993

Treatment of polyarteritis nodosa related to hepatitis B virus with short term steroid therapy associated with antiviral agents and plasma exchanges. A prospective trial in 33 patients.

OBJECTIVE: To test the effectiveness and tolerance of antiviral agents associated with short term immunosuppression in the treatment of polyarteritis nodosa (PAN) related to hepatitis B virus (HBV). METHODS: We conducted a prospective, nonblinded, multicenter trial in which patients with multisystemic PAN related to HBV were included. Every patient initially underwent a short term (2 weeks) treatment with prednisone and then received vidarabine (Vira A) and plasma exchanges. The end point of the study was control of the disease (recovery or remission) or death. RESULTS: Thirty-three patients were included. Every patient had histopathologic or arteriographic evidence of vasculitis and was infected with actively replicating HBV. Disease activity during the first 6 months was controlled in 26 patients (78.8%). Among the 25 patients still alive at the end of the study, 24 (72.7%) had completely recovered with no clinical or laboratory evidence of systemic vasculitis after at least 18 months without treatment. Eight patients died during the study period; 3 of treatment failure, usually early in the course of the disease. One patient died of fulminant hepatitis 3 months after the entry in the study at time of seroconversion. The survival curve showed that at 7 years, 76% of the patients were alive. HBeAg/anti-HBeAb seroconversion was observed in 12 patients (36.3%) after one Vira A cycle. When a 2nd cycle of Vira A or alpha interferon was prescribed, HBeAg/anti-HBeAg seroconversion occurred in 15 patients (45.4%). Two other patients who underwent a 2nd cycle of Vira A administration, had lost HBeAg and no longer expressed serological evidence of replication as assessed by HBV DNA spot hybridization. At the end of the study, 17 (51.5%) no longer expressed serological evidence of HBV replication. This treatment was effective and only minor side effects were noted. CONCLUSIONS: We conclude that this new therapeutic approach to PAN related to HBV effectively controlled systemic vasculitis and was associated with a higher number of recoveries from chronic HBV infections. The development of new antiviral agents, such as interferon alpha 2b, allows us to hope that antiviral therapy will have a role to play as a first line treatment regimen of virus induced vasculitis.

Adult↗