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Biomedical subjects

R Zachoval

Publications and source records attributed to R Zachoval.

At least 55 records · Page 3Linked to original sources
PubMed1995

Possible mechanism involving T-lymphocyte response to non-structural protein 3 in viral clearance in acute hepatitis C virus infection.

In acute hepatitis C virus (HCV) infection only 20-50% of patients spontaneously clear the virus. To characterise the immune reaction during that phase we studied the response of peripheral blood mononuclear cells (PBMC) to the recombinant HCV proteins core, non-structural protein 3 (NS3), NS4, and NS5 in 14 patients with acute hepatitis C. All eight patients with self-limited disease compared with two of six with evolving chronic infection showed an NS3- specific PBMC response (p = 0.015). Of 65 patients with established chronic hepatitis C, five showed a PBMC response to NS3. NS3-specific CD4 T-cell clones from patients with self-limited infection predominantly produced interferon-gamma and may thus support cytotoxic effector mechanisms important for viral clearance.

Acute Disease↗
PubMed1995

Hepatitis C virus infection as a possible risk factor for ductopenic rejection (vanishing bile duct syndrome) after liver transplantation.

Irreversible ductopenic rejection (DR) after orthotopic liver transplantation (OLT) is a major cause of late hepatic allograft failure. A variety of risk factors for DR have been postulated, but they are controversial. All transplant recipients at our institution with graft survival of more than 1 month (n = 120) were examined retrospectively with a view to possible risk factors for DR. These factors included age, sex, underlying liver disease, hepatitis B and C infections, donor-recipient CMV status, post-OLT CMV infections, immunosuppressive regimen, ABO blood type, and HLA class I and class II mismatches. Statistical analysis was performed with the univariate chi-square test or the two-tailed Fischer's exact test. Ten patients (8.3%) developed DR. Seventeen patients had HCV infections after OLT. In this group, the incidence of DR was highest (4 of 17, or 23.5%). This was significantly higher than for all other OLT groups (6 of 103 patients, or 5.8%; P < 0.03). The other factors analyzed did not reach statistical significance, including those that other authors found important for the development of DR. It may well be that hepatitis C infection predisposes one to the development of DR after OLT.

Bile Duct Diseases↗
PubMed1995

A role for chronic hepatitis C virus infection in a patient with cutaneous vasculitis, cryoglobulinemia, and chronic liver disease. Effective therapy with interferon-alpha.

A six-year history of repeated attacks of fatigue, fever, arthralgias, skin changes, Raynaud's phenomenon, and neuropathy is reported in a patient with chronic liver disease. The following diagnoses were made: (1) leukocytoclastic vasculitis; (2) acute urticaria; (3) cryoglobulinemia type II with Raynaud's phenomenon and low serum level of C4; (4) peripheral polyneuropathy; (5) sicca syndrome; and (6) chronic hepatitis C virus infection. Despite therapy with corticosteroids symptoms increased gradually over years. In the first PCR of the nested PCR analysis, HCV-RNA was exclusively detected in the cryoglobulin fraction but not in the serum supernatant, suggesting that antibodies bind HCV particles, forming circulating immune complexes. As diagnoses 1-5 are well-known organ manifestations of cryoglobulinemia, we speculated whether treatment of hepatitis C with IFN-alpha (3 million IU IFN-alpha 2b three times a week) would inhibit HCV replication, decrease the cryocrit level and thereby ameliorate organ manifestations such as neuropathy and vasculitis. During treatment with IFN-alpha only a very weak or no signal could be detected for HCV-RNA in the cryoglobulin fraction as well as in the serum supernatant. This held true also for the serum supernatant in the second PCR. In parallel, cryoglobulin level, immunoglobulins, and liver enzymes decreased substantially to normal or near normal levels. Clinical symptoms-leukocytoclastic vasculitis and neuropathy-disappeared. We conclude that chronic HCV infection is involved in the pathogenesis of cryoglobulinemia and that IFN-alpha might be an effective treatment in these patients.

Chronic Disease↗
PubMed1995

Individuals with antibodies against hepatitis B core antigen as the only serological marker for hepatitis B infection: high percentage of carriers of hepatitis B and C virus.

BACKGROUND/AIMS: Several reports have unequivocally demonstrated that some individuals with antibodies against hepatitis B core antigen as the only serological marker for hepatitis B infection are chronic carriers of the hepatitis B virus. Nevertheless, conflicting data exist about the frequency of this phenomenon; its cause is unknown. METHODS: In a prospective study we tested individuals who were positive for anti-HBc alone for HBV-DNA as well as for coexisting infections with human immunodeficiency virus and hepatitis C virus. RESULTS: Using polymerase chain reaction with primer pairs from three different regions of the hepatitis B virus genome, we found 54 of 164 individuals (32.9%) with anti-HBc alone to be positive for hepatitis B virus, the majority of them showing very low hepatitis B virus concentrations. 14.3% were human immunodeficiency virus positive; half of them were also hepatitis B virus carriers. Surprisingly, 62 of 153 participants (40.5%) in this study showed antibodies against hepatitis C virus, and about two thirds of the latter were also positive for HCV-RNA. This finding could be confirmed by a retrospective analysis of all people tested for hepatitis B virus markers and anti-HCV in our institution during the 2 years before the prospective study was begun. Again, a high correlation was found between the presence of anti-HCV and anti-HBc alone: 49.2% of individuals with anti-HBc only were anti-HCV positive also, compared to 26.8% of HBsAg carriers and only 10% of individuals showing the serological pattern of past hepatitis B. CONCLUSIONS: Thus our study of individuals positive for anti-HBc alone revealed a high number of carriers of hepatitis B virus and hepatitis C virus among them; furthermore, we found some evidence that hepatitis C virus infection may favour this unusual hepatitis B virus marker pattern.

Adult↗
PubMed1995

Activation of a heterogeneous hepatitis B (HB) core and e antigen-specific CD4+ T-cell population during seroconversion to anti-HBe and anti-HBs in hepatitis B virus infection.

Overcoming hepatitis B virus infection essentially depends on the appropriate immune response of the infected host. Among the hepatitis B virus antigens, the core (HBcAg) and e (HBeAg) proteins appear highly immunogenic and induce important lymphocyte effector functions. In order to investigate the importance of HBcAg/HBeAg-specific T lymphocytes in patients with acute and chronic hepatitis B and to identify immunodominant epitopes within the HBcAg/HBeAg, CD4+ T-cell responses to hepatitis B virus-encoded HBcAg and HBcAg/HBeAg-derived peptides were studied in 49 patients with acute and 39 patients with chronic hepatitis B. The results show a frequent antigen-specific CD4+ T-cell activation during acute hepatitis B infection, a rare HBcAg/HBeAg-specific CD4+ T-cell response among HBeAg+ chronic carriers, and no response in patients with anti-HBe+ chronic hepatitis. An increasing CD4+ T-cell response to HBcAg/HBeAg coincides with loss of HBeAg and hepatitis B virus surface antigen (HBsAg). Functional analysis of peptide-specific CD4+ T-cell clones revealed a heterogeneous population with respect to lymphokine production. Epitope mapping within the HBcAg/HBeAg peptide defined amino acids (aa) 1 to 25 and aa 61 to 85, irrespective of the HLA haplotype, as the predominant CD4+ T-cell recognition sites. Other important sequences could be identified in the amino-terminal part of the protein, aa 21 to 45, aa 41 to 65, and aa 81 to 105. The immunodominant epitopes are expressed in both proteins, HBcAg and HBeAg. Our findings lead to the conclusion that activation of CD4+ T lymphocytes by HBcAg/HBeAg is a prerequisite for viral elimination, and further studies have to focus on the question of how to enhance or induce this type of T-cell response in chronic carriers. The immunodominant viral sequences identified may have relevance to synthetic vaccine design and to the use of peptide T-cell sites as immunotherapeutic agents in chronic infection.

Acute Disease↗
PubMed1995

Quantification of hepatitis B virus DNA over a wide range from serum for studying viral replicative activity in response to treatment and in recurrent infection.

A new standardized test for hepatitis B virus (HBV) DNA with increased sensitivity and range over previous assays (30 to 10(6) HBV genomes/test) was evaluated in this study. The quantitative results from the test have been validated using international reference specimens of known titer and a reference solution hybridization test. The test has small variability considering the wide dynamic range. The CV was 14% within one experiment and 32% to 39% between independent experiments. Hepatitis B surface antigen (HBsAg)-negative, anti-HBc-positive blood donor sera (n = 25) were all negative for HBV DNA in the new test, whereas 63% (n = 19) of HBsAg-positive healthy carriers had measurable quantities of HBV DNA. In five example cases of chronic hepatitis B patients responding to alfa-interferon treatment but remaining virus positive, HBV DNA was consistently present in posttreatment sera in a titer range 4 x 10(3) to 10(6)/mL not detectable by the conventional hybridization test. In two complete responders, the HBV DNA titer decreased over six orders of magnitude to below cutoff of the test. In four liver transplant recipients with chronic hepatitis B, viral recurrence was detected by the new test at an early stage much before the clinical relapse. Unlike serology, the test was suitable also in patients under anti-HBs immunoprophylaxis. In conclusion, the new colorimetric polymerase chain reaction (PCR) test allowed thousandfold increased sensitivity in quantification of HBV DNA in patient sera. The test may have future applications in improving assessment of efficacy of antiviral treatment and guiding therapeutic interventions.

Adult↗
PubMed1995

Mapping of immunodominant CD4+ T lymphocyte epitopes of hepatitis C virus antigens and their relevance during the course of chronic infection.

In acute and chronic viral disease the specific response of CD4+ T lymphocytes to certain viral proteins is an essential part of antiviral effector mechanisms. In hepatitis C virus infection, the contribution of the immune system and particularly of CD4+ T lymphocytes to the pathogenesis of disease is unknown. We serially determined the peripheral blood CD4+ T lymphocyte response to several recombinant hepatitis C virus proteins (core, NS3, NS4, NS5) and 17 overlapping synthetic peptides derived from the core sequence over up to 48 months in 43 patients with chronic hepatitis C; of these, 16 had been treated with interferon alfa (IFN). Twelve of 27 untreated patients, 4 of 4 sustained responders to IFN, 7 of 8 patients with a transient response, and 1 of 4 nonresponders showed a proliferative response to hepatitis C virus proteins. The hepatitis C virus core protein was the most immunogenic protein, and fine analysis with peptides indicated amino acids 23 to 42, 66 to 85, and 131 to 150 as immunodominant regions. In a subgroup of nine patients, proliferation assays were performed before or during IFN. In this subgroup, sustained responders but not those with a transient or no response to IFN showed a specific CD4+ immune reaction to hepatitis C viral antigens (P < .05). Infection with hepatitis C virus genotype 3a was significantly associated with a sustained response to IFN (P < .05). In general, a CD4+ T lymphocyte response was more common in patients with chronic hepatitis C who responded to interferon-alpha as compared with nonresponders.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Amanita phalloides intoxications in a family of russian immigrants. Case reports and review of the literature with a focus on orthotopic liver transplantation.

Alpha-amanitin, the main toxin of the death cap fungus (Amanita phalloides) is one of the most dangerous natural poison. This toxin damages eukaryotic cells by inhibiting their transcription. Lesions are seen in cells with rapid protein synthesis, particular in liver and renal cells, even at low toxin concentrations. Without adequate intensive therapy, the outcome of alpha-amanitin poisoning is very poor. This article reports various courses of amanitin intoxication in a family. In 3/4 patients, severe hepatic failure developed as assessed by a decrease of all coagulation factors, mainly Quick's test and factor V (< 10%-15%). Despite vigorous replacement of coagulation factors, in 1 of the patients orthotopic liver transplantation had to be performed on day 4, whereas in all other patients liver function improved spontaneously. All patients survived their intoxication. Both the pharmacological basis and clinical manifestations of Amanita intoxication are discussed. On this basis a treatment scheme is presented which the authors believe may be useful to clinicians.

Adult↗
PubMed1994

Strong transient expression of the type I interferon-induced MxA protein in hepatitis A but not in acute hepatitis B and C.

The human MxA protein is a new specific marker for type I interferon activity both in vitro and in vivo. In the study presented here, this interferon-induced marker, as well as the 2',5'-oligoadenylate synthetases, was measured in circulating mononuclear cells from 21 patients with acute hepatitis A, 20 patients with acute hepatitis B and 14 patients with acute hepatitis C for determination of the activation of the interferon system in these viral diseases. In acute hepatitis A a strong expression (10 of 10 patients) of the MxA protein and the 2',5'-oligoadenylate synthetase activity in peripheral-blood mononuclear cells was observed during the first 2 wk after onset of clinical symptoms. In this period the MxA protein concentrations reached levels similar to those measured in patients treated with up to 5 x 10(6) IU interferon-alpha three times a week. Beyond wk 3, in eight of eight patients with hepatitis A no increased MxA protein levels were found. In contrast, peripheral-blood mononuclear cells from patients with acute hepatitis B contained either no measurable MxA protein or only slightly higher levels of the MxA protein, as did those of most patients (12 of 14) with acute hepatitis C. The MxA protein levels of both hepatitis B and C patients were significantly lower (p < 0.05) than those found in hepatitis A patients. Furthermore, sera from 6 of 10 patients with hepatitis A, but none of 10 patients with acute hepatitis B and C, contained measurable MxA protein. This serum MxA protein may originate from interferon-exposed and subsequently damaged liver cells.(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗
PubMed1993

Increased frequency of CD8+ CD45R0+ memory T lymphocytes in acute hepatitis B virus infection.

CD8+ lymphocytes of the memory subset (= CD45R0+) encompass antigen-specific effector cells, which are believed to be decisive for virus elimination in several viral infections. To determine whether this can be extended to HBV infection naive and memory T cells were studied among CD(4+)- and CD(8+)-lymphocytes and used monoclonal antibodies in two-color flow cytometric analysis to quantitate functional T cell subsets in peripheral blood of patients with acute hepatitis B (n = 11), chronic hepatitis B (n = 24) and healthy individuals (n = 26). Compared to CD4+ populations of healthy individuals the number of total CD4+ lymphocytes in patients with both acute or chronic hepatitis was significantly reduced. In contrast CD8+ cells did not significantly change in either acute and chronic hepatitis. Analysis of naive and memory subsets demonstrated, however, a significant rise in CD45R0+ memory cells from 5 to 15% (70% of all CD8+ cells) in acute hepatitis. These changes within the CD8+ population were, however, restricted to the acute phase of hepatitis in that the frequency of CD8+CD45R0+ decreased within weeks post infection. Furthermore, patients with chronic hepatitis did exhibit normal values of CD8+ memory cells (30% of all CD8+ cells). These findings suggest that enrichment of CD8+CD45R0+ memory cells reflects an accumulation of functional effector cells, which may be specifically activated by viral antigens and determine the outcome of infection.

Acute Disease↗
PubMed1993

Production of human cloned antibodies specific for hepatitis D virus-encoded small and large protein.

Cloned antibodies to specific epitopes of hepatitis D virus were produced by transformation with Epstein-Barr virus and subsequent cloning of peripheral blood B lymphocytes from a patient with chronic hepatitis D virus infection. Several stable cloned B cell lines, derived from two parent cultures, produced hepatitis D-virus-specific IgG antibodies. Some cloned IgG antibodies detected hepatitis D virus-associated antigen in hepatitis D virus-infected woodchuck liver tissue sections by indirect immunofluorescence staining and some reacted in an inhibition ELISA test detecting hepatitis D virus antibodies; most cloned IgG lines detected hepatitis D antigen both in immunofluorescence tests and in inhibition ELISA. Cloned antibodies to hepatitis D antigen detected by ELISA and/or immunofluorescence staining recognized the two major specific native and denatured polypeptides, p27 and p29, in Western blot analysis. Such cloned antibodies for hepatitis D virus are potentially useful for clinical diagnosis and research.

Antibodies, Viral↗
PubMed1992

Detection and characterization of hepatitis C virus sequence in the serum of a patient with chronic HCV infection.

A cDNA fragment corresponding to the nonstructural gene region of Hepatitis C virus was cloned and sequenced. cDNA was obtained by reverse transcription of viral RNA extracted from serum of a German patient with chronic post transfusion hepatitis. "Nested" PCR resulted in a cDNA fragment of 345 nt. The sequence showed a homology of 96% to the American prototype HCV.

Base Sequence↗
PubMed1992

T lymphocytes from patients with primary biliary cirrhosis produce reduced amounts of lymphotoxin, tumor necrosis factor and interferon-gamma upon mitogen stimulation.

Primary biliary cirrhosis (PBC) is considered an autoimmune disease characterized by destruction of small intrahepatic bile ducts by lymphocytes. Altered functions of these lymphocytes might reflect an abnormal immune response leading to tissue damage. We investigated lymphokine secretion by mitogen-stimulated T lymphocytes from the liver biopsies of patients with PBC and for comparison also peripheral blood. In PBC, diminished synthesis of lymphotoxin (TNF beta), tumor necrosis factor (TNF alpha) and interferon-gamma (IFN gamma) was found both in T-cell lines from liver tissue and in peripheral blood. The reduction was most prominent for TNF beta in early histological stages of PBC, and appeared to be a stable phenomenon when T cells were tested after long-term tissue culture. Analysis of mRNA levels indicates a possible link between reduced TNF beta production and a defect in interleukin-2 transcription. The data suggest that diminished lymphokine production in patients with PBC may play an important role in the immunopathogenesis of this disease.

Adult↗
PubMed1991

Characterization of nucleotide sequences from European hepatitis C virus isolates.

We characterized the 5' end and parts of the structural genes of European isolates of hepatitis C virus (HCV) and compared them with recently published RNA sequences of American and Japanese HCV isolates. The cDNA, obtained by reverse transcription of viral RNA extracted from different sera, was amplified by nested PCR, cloned and sequenced. Within 239 nucleotides (nt) of the 5' end, we found only three single-nt exchanges compared to two sequences of Japanese origin and one exchange to the prototype HCV sequence (ptHCV) (homology greater than 99%). The sequence of the core region (534 nt) in two European isolates showed a homology of about 97-98% on the nt level, as compared to ptHCV and one Japanese isolate, and 90% to other Japanese isolates. The amino acid (aa) homology was between 98-99% among all published sequences. A greater discrepancy was found in the European isolates within the 434 nt sequenced from the N-terminus of the putative envelope region, where the nt homology to ptHCV and one Japanese isolate was 90-93% (aa homology 93-95%), and to other Japanese isolates was 72-73% (aa homology 77-78%), indicating that the European isolates may be more closely related to the ptHCV and one Japanese isolate than to the other Japanese isolates. Amplified genes encoding structural proteins (core, envelope) were expressed in Escherichia coli. Sera from chronically infected patients reacted strongly with the recombinant core protein, but no specific immunoreactivity occurred with the putative envelope protein.

Amino Acid Sequence↗
PubMed1991

Hepatitis B virus antigen-specific T-cell activation in patients with acute and chronic hepatitis B.

Since the hepatitis B virus is noncytopathic, it is generally believed that the individual specific immune response determines the course of infection. The lack of data about hepatitis B virus-specific T-cell reactions in acute infection led us to investigate the specific cellular immune response of infected individuals in terms of proliferation, and gamma-interferon and lymphotoxin production. Our results demonstrate that peripheral blood mononuclear cells (PBMNC) from patients with acute and chronic hepatitis B respond weakly to HBsAg. In contrast, patients with acute hepatitis show a vigorous response to the nucleocapsid antigen (HBcAg) in terms of proliferation and lymphokine production, while only few chronic virus carriers gave a proliferative response. Either of the antigens could activate lymphocytes to produce gamma-interferon and lymphotoxin, cytokines which may modulate antiviral immune response.

Acute Disease↗