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X Forns

Publications and source records attributed to X Forns.

At least 19 recordsLinked to original sources
PubMed2006

Sensitivity to antiviral therapy may change after liver transplantation in patients with chronic hepatitis C virus infection.

In hepatitis C virus (HCV)-infected patients, it is generally assumed that the pattern of response to antiviral therapy remains unaltered after liver transplantation (LT). However, changes in the circulating HCV quasispecies and in the gene expression profiles of the graft might influence response to treatment after LT. We evaluated 22 HCV-infected patients who received antiviral treatment while awaiting LT and in whom HCV infection recurred. Eleven of these patients underwent a new antiviral treatment course. Our study analyses the early virological response to both treatment courses to assess the influence of the changes in HCV on the response to therapy. Patients were considered early virological responders (EVR) if viral load declined > or = 2 log10 during the first 12 weeks of therapy. The remaining individuals were considered nonresponders (NR). HCV sequences from hypervariable region 1 and nonstructural 5A (NS5A) region before both treatment regimens were compared. Of 11 patients, 8 (73%) showed identical early response to both courses of therapy (group A: five EVR-EVR, three NR-NR). Interestingly, the response changed in three patients (27%) (group B): two NR became EVR after transplantation, whereas one EVR became NR. Fixation of mutations within the NS5A occurred preferentially in group B (100%) compared with group A (37%)(P = 0.12). However, the number of fixed mutations was not significantly different between groups, suggesting that the changes in sensitivity to therapy after LT are not exclusively dependent on variations in HCV strains. In conclusion, in HCV-infected patients undergoing LT, the pattern of response to antiviral treatment may change after transplantation, and this possibility needs to be incorporated in clinical practice.

Adult↗
PubMed2003

[Adult living donor liver transplantation. Analysis of the first 30 cases].

INTRODUCTION: In the last 2-3 years, adult living donor liver transplantation (ALDLT) has been developed on an international scale, multiplying the number of procedures performed. Despite this, analysis of the results is still incomplete. The aim of the present study was to perform a descriptive analysis of the results after the first 3 years of the initiation of the program. MATERIAL AND METHODS: During this period, 30 ALDLT were performed. In all procedures, right lobe grafts were used. The mean age of donors and recipients was 31.8 and 52.7 years, respectively. The main indication for liver transplantation was liver cirrhosis due to hepatitis C virus (70%) and 38% of recipients were stage C in the Child-Pugh classification. A total of 46.7% of recipients had hepatocellular carcinoma. RESULTS: Donors: The mean volume of the remnant liver was 632 cc (40.5% of the previous hepatic mass). Ten donors (33%) presented complications. The most frequent complication was biliary fistula (20%) and three patients required reintervention. The mean length of hospital stay among donors was 11.7 days. Recipients: The mean weight of the graft was 775 g, with a mean difference between graft weight and that of the recipient of 1.11. Fifteen recipients (50%) presented biliary leaks and nine of these (30%) required reintervention. There were no graft losses for technical reasons. Four patients died. With a median follow-up of 14 months, actuarial survival at 18 months was 92.9%. CONCLUSION: ALDLT is an effective method for reducing the number of patients on the waiting list. The probability of survival is similar to that of cadaveric transplantation. Biliary complications in the recipient constitute a problem, the long-term repercussions of which remain to be resolved.

Adolescent↗
PubMed2001

Long-term follow-up of chronic hepatitis C in patients diagnosed at a tertiary-care center.

BACKGROUND/AIMS: The natural history of chronic hepatitis C (HCV) is not completely understood. This study was aimed to evaluate the long-term outcome of the disease over a prolonged period of time and to identify factors associated with progression. METHODS: One hundred and sixteen patients with non-cirrhotic chronic non-A, non-B hepatitis consecutively diagnosed at a tertiary hospital between 1971 and 1977 were followed until December 1998 or until death. Patients with significant alcohol intake were excluded from the study. Variables obtained at the time of diagnosis, including epidemiological, clinical, laboratory, and histological data were recorded to determine risk factors associated with the development of liver cirrhosis and hepatic decompensation. RESULTS: Based on complete follow-up data, the development of liver cirrhosis and hepatic decompensation was evaluated in 94 and 114 of the 116 patients, respectively. Thirty-seven (39.3%) of 94 patients developed liver cirrhosis; an aspartate aminotransferase (AST) value higher than 70 IU/L was associated with development of cirrhosis (odds ratio (OR) 4.22, 95% CI 1.3-13.8). Hepatic decompensation occurred in 12 (10.5%) of 114 patients, its cumulative probability being 2.8% at 10 years, 5.2% at 15 years and 19.8% at 20 years. The only factor independently associated to the development of hepatic decompensation was the presence of fibrosis (stage 2 or 3) in the initial liver biopsy (OR 4.1, IC 95% 1.22-13.9). Liver-related death occurred only in seven (6%) of 114 patients. In comparison with the 116 patients diagnosed in the 1970's, patients with chronic hepatitis C diagnosed in 1999 were younger, more often asymptomatic, had lower AST and alanine aminotransferase (ALT) values and had significantly lower grade and stage histological scores. CONCLUSIONS: In summary, chronic hepatitis C had a high rate of progression to liver cirrhosis over a prolonged follow-up. However, this might be related to the fact that two decades ago the diagnosis was made at a significantly more advanced stage of the disease. Patients at high risk of progression can be identified by biochemical and histological variables at the time of diagnosis.

Adult↗
PubMed2001

High amino acid variability within the NS5A of hepatitis C virus (HCV) is associated with hepatocellular carcinoma in patients with HCV-1b-related cirrhosis.

Interferon therapy may decrease the risk of hepatocellular carcinoma in patients with hepatitis C virus (HCV)-related liver cirrhosis. Interaction of the cellular protein kinase PKR with the PKR-binding domain (PKR-bd) of HCV-NS5A protein may affect cellular growth control and viral resistance to interferon therapy. Mutations within the PKR-bd, which comprises the interferon sensitivity determining region (ISDR), have been associated with interferon sensitivity. To determine whether or not there is an association between HCV heterogeneity and the presence of hepatocellular carcinoma, HCV-1b genomic regions were amplified and directly sequenced from serum samples obtained from 82 patients with liver cirrhosis, 53 with, and 29 without hepatocellular carcinoma. None of them had received antiviral therapy. When compared with the deduced consensus sequence, the median number of amino acid changes in the PKR-bd was higher among samples from patients with (4.22) than from those without hepatocellular carcinoma (1.62; P <.001), and isolates with 3 or more amino acid changes were significantly more common among the former (60%) than among the later (6%, P <.001). No such differences were observed in other viral regions, including Core, E2-HVR-1, E2-PePHD, NS3, and the 5' and 3' PKR-bd flanking regions. In addition, amino acid variation in viral regions other than HVR-1 did not accumulate over time in the analyzed sequential serum samples obtained from patients with or without hepatocellular carcinoma. Therefore, a mutated HCV-PKR-bd phenotype is very common in cirrhotic patients with hepatocellular carcinoma.

Aged↗
PubMed2001

Studies of hepatitis C virus in chimpanzees and their importance for vaccine development.

Persistent infection with hepatitis C virus (HCV) is an important cause of chronic liver disease worldwide. Therefore, the development of vaccines to prevent HCV infection, or at least to prevent progression to chronicity, is a major goal. Potential HCV vaccine candidates include recombinant proteins, recombinant viruses, DNA constructs, synthetic peptides and virus-like particles. Various vaccine candidates have been shown to generate humoral and cellular immune responses in animals, primarily in mice. However, the efficacy of most vaccine candidates in protecting against HCV has not been tested because the chimpanzee, the only animal other than humans that is susceptible to HCV, is not readily available, requires special facilities, and is very expensive. The course of infection in chimpanzees is similar in its diversity to that in humans and detailed studies in this model are beginning to define the immune responses that can terminate HCV infection. Of relevance for vaccine evaluation was the titration in chimpanzees of different HCV variants to provide well-characterized challenge pools. In addition, monoclonal virus pools generated from chimpanzees infected with cloned viruses make it possible now to examine immunity to HCV without the confounding factor of antigenic diversity of the challenge virus (quasispecies). The vaccine trials performed in chimpanzees to date all have tested the efficacy of immunizations with various forms of the envelope proteins of HCV.

Animals↗
PubMed2001

Influence of the genetic heterogeneity of the ISDR and PePHD regions of hepatitis C virus on the response to interferon therapy in chronic hepatitis C.

Two genomic regions of hepatitis C virus (HCV), the interferon sensitivity-determining region (ISDR) of the non-structural 5A gene (NS5A) and the protein kinase-RNA activated (PKR)-eukariotic transcription factor (eIF2-alpha) phosphorylation homology domain (PePHD) of the structural E2 gene, interact in vitro with the interferon-inducible cellular PKR protein kinase. Mutations within these regions might, therefore, influence the response to interferon therapy. Viral load at baseline and sequence heterogeneity of HCV in NS5A and E2 regions was studied in 74 HCV-1b and in 12 HCV-3a infected patients with chronic hepatitis C who were treated with interferon. As previously reported by us, in a smaller series of patients in which the ISDR region was analyzed [Saiz et al. (1998) Journal Infectious Diseases 177:839-847], in the present study a low viral load and a high number of amino acid mutations within the ISDR, but not within the PePHD region, were significantly associated with long-term response to interferon among HCV-1b infected patients. No relationship between these viral features and response to therapy was disclosed in patients infected with HCV-3a.

Adult↗
PubMed2000

Hepatitis C virus envelope protein E2 binds to CD81 of tamarins.

Since recombinant envelope glycoprotein E2 of hepatitis C virus (HCV) binds to CD81 on human and chimpanzee cells, it has been suggested that CD81 may be a receptor for HCV. Humans and chimpanzees are the only species known to be susceptible to HCV infection. E2 has been reported not to bind to CD81 of the African green monkey, mouse, or rat, suggesting that binding of HCV to CD81 is species specific and may determine susceptibility to infection with HCV. We investigated the interaction between E2 of HCV and CD81 of tamarins, a group of small New World monkeys frequently used for the study of human viruses. Tamarins are not susceptible to HCV infection. Nonetheless, we found that three different forms of HCV E2 (intracellular, secreted, and cell surface-displayed) bound more efficiently to recombinant tamarin CD81 than to human CD81, as determined by ELISA and immunofluorescence. The affinity of the interaction was approximately 10-fold higher for tamarin than for human CD81. Binding of E2 to CD81 on cultured or primary tamarin cells was demonstrated by flow cytometry. In contrast to previous reports, there was also a low-affinity interaction between E2 and African green monkey CD81. Thus, the HCV E2 interaction with CD81 is not limited to humans and chimpanzees and does not predict susceptibility to HCV infection.

Amino Acid Sequence↗
PubMed2000

Hepatitis C virus lacking the hypervariable region 1 of the second envelope protein is infectious and causes acute resolving or persistent infection in chimpanzees.

Persistent infection with hepatitis C virus (HCV) is among the leading causes of chronic liver disease. Previous studies suggested that genetic variation in hypervariable region 1 (HVR1) of the second envelope protein, possibly in response to host immune pressure, influences the outcome of HCV infection. In the present study, a chimpanzee transfected intrahepatically with RNA transcripts of an infectious HCV clone (pCV-H77C) from which HVR1 was deleted became infected; the DeltaHVR1 virus was subsequently transmitted to a second chimpanzee. Infection with DeltaHVR1 virus resulted in persistent infection in the former chimpanzee and in acute resolving infection in the latter chimpanzee. Both chimpanzees developed hepatitis. The DeltaHVR1 virus initially replicated to low titers, but virus titer increased significantly after mutations appeared in the viral genome. Thus, wild-type HCV without HVR1 was apparently attenuated, suggesting a functional role of HVR1. However, our data indicate that HVR1 is not essential for the viability of HCV, the resolution of infection, or the progression to chronicity.

Animals↗
PubMed2000

Characterization of modified hepatitis C virus E2 proteins expressed on the cell surface.

The envelope proteins of hepatitis C virus (HCV) are the likely targets of neutralizing antibodies and their molecular and functional characterization is relevant for vaccine development. We previously showed that surface-expressed E2 is a better immunogen than intracellular E2 and, therefore, we were interested in exploring more efficient ways to present E2 protein on the cell surface. We found that E2 targeted to the cell surface by replacement of its transmembrane domain did not bring E1 to the surface although E1 could be expressed independently on the cell surface if its transmembrane domain was similarly replaced. FACS analysis suggested that E2 expressed on the cell surface acquired its native conformation more efficiently when truncated at aa 661 than when truncated at aa 715. The shorter form of truncated E2 better retained the ability to bind the second extracellular loop (EC2) of CD81, the putative HCV receptor. Interestingly, deletion of the hypervariable region 1 (HVR1) did not perceptibly alter E2 structure; cell-surface forms of E2 lacking the HVR1 remained reactive with conformation-sensitive MAbs and were able to bind recombinant EC2 of CD81.

Amino Acids↗
PubMed2000

Pre-treatment with prednisolone does not improve the efficacy of subsequent alpha interferon therapy in chronic hepatitis C.

BACKGROUND/AIMS: Alpha interferon administration is quite disappointing as a single therapy in chronic hepatitis C. A brief course of corticosteroid therapy might increase the effectiveness of subsequent alpha interferon administration, but data on this issue are controversial. METHODS: One hundred and fifty-six consecutive patients with chronic hepatitis C were randomly assigned to be treated blind with tapering doses of oral prednisolone or placebo for 4 weeks. Two weeks after cessation of therapy, patients received alpha interferon (3 MU t.i.w.) for 48 weeks and were followed for 24 additional weeks. Response was defined by the presence of normal alanine aminotransferase (ALT) and negative HCV-RNA in serum. RESULTS: ALT activity decreased during prednisolone administration and rebounded upon withdrawal in 38% of the patients treated with this drug. Significant changes in serum bilirubin were not observed. HCV-RNA serum concentration tended to increase during prednisolone administration and to decrease upon withdrawal. ALT and HCV-RNA did not change during administration of placebo. At the end of interferon administration, 33% of patients treated with prednisolone and 25% of those treated with placebo presented biochemical and virological response. At the end of post-treatment follow-up, response was maintained in 12% and 13% of patients treated with prednisolone or placebo respectively. Response was not related to ALT or HCV-RNA changes observed during the pre-interferon phase of the study. No adverse events related to prednisolone administration were observed. CONCLUSIONS: Prednisolone administration and withdrawal induced a rebound in ALT activity and a decrease in HCV-RNA serum concentration in about one third of the patients with chronic hepatitis C. However, these changes did not enhance the effectiveness of subsequent alpha interferon therapy.

Adult↗
PubMed2000

Vaccination of chimpanzees with plasmid DNA encoding the hepatitis C virus (HCV) envelope E2 protein modified the infection after challenge with homologous monoclonal HCV.

Hepatitis C virus (HCV) is an important cause of chronic liver disease worldwide. Development of vaccines to prevent HCV infection, or at least prevent progression to chronicity, is a major goal. In mice and rhesus macaques, a DNA vaccine encoding cell-surface HCV-envelope 2 (E2) glycoprotein stimulated stronger immune responses than a vaccine encoding intracellular E2. Therefore, we used DNA encoding surface-expressed E2 to immunize chimpanzees 2768 and 3001. Chimpanzee 3001 developed anti-E2 after the second immunization and antibodies to hypervariable region 1 (HVR1) after the third immunization. Although chimpanzee 2768 had only low levels of anti-E2 after the third immunization, an anamnestic response occurred after HCV challenge. CTL responses to E2 were not detected before challenge, but a strong response was detected after HCV challenge in chimpanzee 2768. An E2-specific CD4+ response was detected in chimpanzee 2768 before challenge and in both chimpanzees postchallenge. Three weeks after the last immunization, animals were challenged with 100 50% chimpanzee-infectious doses (CID(50)) of homologous monoclonal HCV. As a control, a naive chimpanzee was inoculated with 3 CID(50) of the challenge virus. The vaccine did not generate sterilizing immunity because both vaccinated chimpanzees were infected. However, both vaccinated chimpanzees resolved the infection early whereas the control animal became chronically infected. Compared with the control animal, hepatitis appeared earlier in the course of the infection in both vaccinated chimpanzees. Therefore, DNA vaccine encoding cell surface-expressed E2 did not elicit sterilizing immunity in chimpanzees against challenge with a monoclonal homologous virus, but did appear to modify the infection and might have prevented progression to chronicity.

Animals↗
PubMed1999

DNA immunization of mice and macaques with plasmids encoding hepatitis C virus envelope E2 protein expressed intracellularly and on the cell surface.

We analyzed the humoral immune response elicited by hepatitis C virus (HCV) E2 protein expressed in vivo after injection of plasmid DNA into mice and rhesus macaques. Three plasmids were used for immunization: a plasmid containing the entire sequence of the E2 and p7 genes (pE2); a plasmid encoding a truncated form of the E2 protein targeted to the cell surface (pE2surf); a control plasmid (pDisplay) lacking an HCV insert. Each plasmid was injected intramuscularly into 5 mice and intraepidermally (via gene gun) into 5 mice. Immunization was repeated three times at three week intervals. Five macaques were injected intramuscularly (two with pE2, two with pE2surf and one with pDisplay) and immunization was repeated after 8 weeks. All mice immunized via gene gun with pE2 or pE2surf developed anti-E2. The animals immunized with pE2surf developed an earlier and stronger humoral immune response than those immunized with pE2. Only 2 of the mice injected by the intramuscular route, both immunized with pE2surf, developed detectable anti-E2. One of the two macaques immunized with pE2 and both macaques immunized with pE2surf developed anti-E2; the humoral immune response was much stronger in the animals immunized with pE2surf. Our results suggest that presentation of HCV E2 on the cell surface may increase its immunogenicity while preserving its ability to react with antibodies generated during a natural infection.

Animals↗
PubMed1999

Comparative study of a modified competitive RT-PCR and Amplicor HCV monitor assays for quantitation of hepatitis C virus RNA in serum.

A modified competitive RT-PCR (mcRT-PCR) to measure HCV RNA in serum and the Amplicor HCV Monitor assay were compared. For mcRT-PCR, the RNA extracted was retrotranscribed and coamplified in one step with a known amount of a DNA internal control (IC). Digoxigenin-labeled amplified products were hybridized to specific HCV DNA and IC-DNA probes and quantified by colorimetry. HCV RNA concentration was calculated by plotting the ratio of HCV/IC ODs against a calibration curve. Multiple samples were analyzed in the same round and tedious titration of each sample with a competitor was unnecessary. The mcRT-PCR assay was linear from 6 x 10(3) to 6 x 10(7) copies/ml, whereas Amplicor was linear up to 1-2 x 10(6) copies/ml. HCV RNA was measured in samples from 75 carriers. There was agreement between both methods in type 1 infections but not in type 2 or type 3 infections, in which the values measured by Amplicor were, on average, 15 times lower than those measured by the mcRT-PCR. HCV RNA measured by Amplicor was higher in type 1 infections than in type 2 or 3 infections, but no differences were found when viral load was assessed by mcRT-PCR. The binding efficiency of the Amplicor-probe was greater for type 1 than for types 2 or 3, suggesting Amplicor underestimates the viral load in the latter types. In contrast, the mcRT-PCR is not affected by genotype-related variation of HCV. This study suggests that mcRT-PCR assay is reliable for sensitive and accurate measurement of HCV RNA over a broad range of values independently of the HCV genotype.

Genotype↗