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Biomedical subjects

R Zachoval

Publications and source records attributed to R Zachoval.

At least 73 records · Page 4Linked to original sources
PubMed1990

Endogenous interferon (IFN) in patients with acute hepatitis B.

The occurrence of serum interferon was studied in 39 patients with acute viral hepatitis B. Antiviral activity of interferon in serum was determined by measuring the inhibition of the CPE of vesicular stomatitis virus on bovine kidney cells (MDBK). Among these patients only 5 (12.8%) had detectable serum interferon level during the first week of hospitalization. The antiviral activity of the interferon-positive sera was low (5-10 IU/ml).

Acute Disease↗
PubMed1988

Interferon alpha in hepatitis type B and non-A, non-B. Defective production by peripheral blood mononuclear cells in chronic infection and development of serum interferon in acute disease.

The production in vitro of interferon alpha and gamma by peripheral blood mononuclear cells of 25 patients with chronic hepatitis B and 13 patients with chronic hepatitis non-A, non-B was compared to that of healthy controls. Following induction by Molt 4 leukemia cells (P less than 0.001) and influenza A/X31 virus (P less than 0.01), there was a significantly lower interferon alpha response in patients with chronic hepatitis B and chronic hepatitis non-A, non-B. Yields of interferon gamma in patients with chronic hepatitis were comparable to those of normal individuals. The degree of interferon deficiency did not correlate with severity of liver disease. In patients with chronic hepatitis B, viral replication (presence or absence of HBeAg) was not related to the defect in interferon alpha production. Three of 10 patients with acute hepatitis B had measurable antiviral activity in the serum for 3-5 days after the onset of jaundice.

Acute Disease↗
PubMed1986

Cytolytic T cell clones derived from liver tissue of patients with chronic hepatitis B.

To study the role of cell-mediated immunity in chronic hepatitis B (cHB) we have cloned T cells from liver biopsies of 14 patients with cHB. As a first step, T cell lines were established from lymphocytes infiltrating the liver by culturing the biopsied specimens with autologous feeder cells and interleukin 2 (IL2). Fifty-eight clones obtained by limiting dilution showed phenotypic stability over periods of 2-26 weeks. Of the 58 clones 50 were of the "cytotoxic/suppressor" T cell subset (CD8) as defined by the monoclonal antibody T811. Only 8 of 58 clones were of the "helper/inducer" phenotype (CD4) as defined by the monoclonal antibody T151. Functional studies on 9 clones (7 of CD8+ phenotype, 2 of CD4+ phenotype) revealed high cytotoxic activity of all of these clones in a lectin-dependent cell-mediated cytotoxicity assay reflecting the killing capacity of cytotoxic T lymphocytes. All 9 clones lacked significant natural killer activity, while two additional CD8+ clones that also expressed the VEP13 antigen showed significant natural killer activity. For none of the clones tested could killer cell activity (ADCC) be demonstrated. The studies demonstrate that the clonal expansion of T lymphocytes from liver biopsies of patients with cHB in the absence of detectable antigen is possible. The propagation of in vivo activated cytolytic T lymphocytes points to an active role of these cells in the pathogenesis of this disease.

Adult↗
PubMed1985

[Persistence of antibodies against hepatitis B surface antigens after vaccination against hepatitis B].

In 195 patients vaccinated against hepatitis B the course of anti-HBs concentration was followed over 4 years. Persistence of anti-HBs proved to be dependent on the level of anti-HBs concentration after basal immunization: in 14 subjects with a maximal anti-HBs level between 10 and 100 IU/l the level had dropped to less than 10 IU/l (considered to be the lowest prophylactic concentration), while 7 were anti-HBs negative. Of those who had 101-1000 IU/l after initial immunization 49% had anti-HBs levels under 10 IU/l after 4 years, while 18% were negative. Among subjects with concentrations 1001-10 000 IU/l after the third immunization only 7% had values below 10 IU/l after 4 years, 4.2% were negative. All those who, after the third immunization, had had anti-HBs levels above 10 000 IU/l, 4 years later still had anti-HBs levels of more than 100 IU/l (mean 581 IU/l). Quantitative anti-HBs determination after triple vaccination against hepatitis B thus makes it possible to predict the duration of protection and to determine the timing of re-vaccination.

Adult↗
PubMed1985

Production of interferon alpha and interferon gamma by peripheral blood leukocytes from patients with chronic hepatitis B virus infection.

Peripheral blood leukocytes from patients with chronic hepatitis B virus (HBV) infection were studied for their capacity to produce interferon (IFN) alpha or IFN gamma. Yields of IFN alpha in leukocyte cultures stimulated with influenza A virus or human leukemic cells were significantly lower than those obtained from healthy controls. Production of IFN gamma in response to induction with protein A of Staphylococcus aureus was also significantly diminished. Defects of IFN production in leukocyte cultures showed no correlation with active viral replication or the degree of severity of HBV-associated liver disease. The demonstration of partial defects of endogenous IFN production provides a rationale for using IFN replacement therapy in patients with chronic HBV infection.

Adolescent↗
PubMed1984

Passive/active immunization against hepatitis B.

No differences in eventual immune-response rates were found between 325 subjects immunized passively/actively against hepatitis B and a control group of 108 subjects vaccinated only actively. The geometric mean titers of antibodies to hepatitis B surface antigen were nearly identical in controls and in a group of 87 individuals immunized passively/actively with the same vaccine lot. Lower geometric mean titers of antibodies to hepatitis B surface antigen were seen in 238 individuals who were vaccinated passively/actively with a different vaccine lot, a difference that may be explained by a somewhat lower immunogenicity in this particular lot. The mean half-life of hepatitis B immunoglobulin was calculated as 24.8 days, and in approximately 90% of vaccines 300,000 mIU of hepatitis B immunoglobulin provided protection until an active immune response had developed.

Adult↗
PubMed1983

Comparison of hepatitis B core antigens derived from human liver or synthesized in Escherichia coli and evaluation of their use in diagnostic assays for anti-HBc IgM.

Hepatitis B core antigen (HBcAg) synthesized in Escherichia coli (clone PR1-11) was compared with HBcAg purified from a liver obtained at autopsy of a patient with chronic active hepatitis B. The molecular weight determined by SDS-PAGE with subsequent transfer of the proteins to nitrocellulose paper, incubation with 125I anti-HBc and exposure to X-ray film, was about 21,000 for HBcAg synthesized in E. coli and was slightly lower for the liver-derived HBcAg. In CsCl density gradients the liver-derived HBcAg had one peak at 1.32 g/ml, and the HBcAg synthesized in E. coli had two peaks at 1.34 and 1.30 g/ml. In a comparison of the immunological activity of both antigen preparations in an enzyme immunoassay, the liver-derived HBcAg was detected only up to a dilution of 1:320, whereas the HBcAg synthesized in E. coli was detected in dilutions up to 1:100,000. With both antigens, the same percentage of sera were positive for anti-HBc IgM from patients with acute (100%), convalescent (61%), past (5%) and chronic active (29-37%) hepatitis. These results indicate that tests for anti-HBc IgM performed with HBcAg synthesized in E. coli are at least as sensitive and specific as those using liver-derived HBcAg.

Antibodies, Viral↗
PubMed1982

Diagnostic significance of quantitative determination of hepatitis B surface antigen in acute and chronic hepatitis B infection.

HBsAg was determined quantitatively by radioimmunoassay and by Laurell electrophoresis in sera of 90 patients with acute hepatitis B, 57 patients with chronic hepatitis B, and 154 HBsAg positive blood donors. Of 55 patients with clearance of HBsAg from the circulation within six months, 54 (98%) showed an at least 50% reduction in concentration within 16 days. All 55 patients had such a decrease within 20 days. No such decrease was found in seven patients with acute hepatitis B who became HBsAg carriers. Therefore, quantitative HBsAg concentration in paired sera seems to be a reliable and early prognostic marker in acute hepatitis B. In patients with clearance of HBsAg most of the antigen is already present in the circulation at hospitalization and is eliminated with a mean half-life of 8.8 days. Patients with chronic hepatitis exhibit on average nearly the same HBsAg concentration (about 40,000 ng/ml) as patients with acute hepatitis B at hospitalization (about 39,000 ng/ml) and HBsAg positive blood donors on average a lower HBsAg concentration (about 8,000 ng/ml).

Blood Donors↗