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Biomedical subjects

B Flehmig

Publications and source records attributed to B Flehmig.

At least 55 records · Page 3Linked to original sources
PubMed1988

Partial purification of (a) low molecular weight ovine pineal compound(s) with an inhibiting effect on the growth of human melanoma cells in vitro.

An in vitro human melanoma cell assay was used to work up the partial purification of (a) low molecular weight (MW) substance(s) from aqueous extracts of ovine pineal tissue shown to contain a growth-inhibiting activity. A combination of paper chromatography, ion-exchange and reverse-phase high performance liquid chromatography with post-column antitumor assay has been developed. This allows a specific identification of an ovine pineal factor (MW less than 500) which inhibits the growth of human melanoma cells in vitro. The substance was partially purified to about 1,000 times as compared to the IC100-value of the starting material (retentate 5). The growth inhibition of human melanoma cells in culture was complete at a dose of 0.1 microgram/ml of purified pineal factor(s). It was demonstrated that the activity of this pineal compound differs from some substances known to be present in the pineal, such as melatonin, serotonin, peridines and beta-carbolines. The activity was not destroyed by treatment with proteolytic enzymes.

Animals↗
PubMed1988

Human gamma interferon production by cytotoxic T lymphocytes sensitized during hepatitis A virus infection.

The production of interferon (IFN) during a chromium-51 release assay with hepatitis A virus (HAV)-infected fibroblasts and autologous peripheral blood lymphocytes from patients with acute HAV infection was studied to determine whether IFN plays a role in immunopathogenesis of hepatitis A infection in humans. Skin fibroblasts of eight patients after acute HAV infection and from two control persons without history of current or past HAV infection were infected with HAV. Peripheral blood lymphocytes were collected at different times after the onset of icterus and tested in a chromium-51 release assay against autologous HAV-infected skin fibroblasts for their cytolytic and IFN-producing activity. The IFN produced during the assay was characterized and found to have the properties of human gamma IFN. Cytotoxicity and gamma IFN release were virus specific. The cell types responsible for both functions were characterized and found to be in the HLA-dependent T8+ lymphocyte subset. Considering that gamma IFN has an antiviral effect on persistent HAV infection in vitro and that it probably accounts for stimulation of HLA class I antigen expression on hepatocytes, our experimental results presented here demonstrate that human gamma IFN produced by HAV-specific T cells may participate in pathogenesis of hepatitis A infection in humans.

Cells, Cultured↗
PubMed1988

[Vaccines against hepatitis viruses].

A short characterization of hepatitis A virus and hepatitis B virus is given. The development of hepatitis B vaccines is described, including the presently available vaccines. Experimentally developed vaccines and possible vaccine developments against hepatitis B virus are discussed. The current status of the development in the field of hepatitis A virus vaccines is presented. Results of hepatitis A live vaccines as well as results of hepatitis A killed vaccine developments are reported.

Hepatitis B Surface Antigens↗
PubMed1987

Immunogenicity of a hepatitis A virus vaccine.

Hepatitis A virus (HAV) strain HAV/HFS/GBM was adapted to and grown in human diploid fibroblast cells. The HAV was concentrated by ammonium sulphate precipitation and high-speed centrifugation. The virus was inactivated by beta-propiolacton and purified by sedimentation through a 20% solution of sucrose and by CsCl gradient centrifugation. The immunogenicity of different preparations was tested in mice, guinea pigs, and goats. The immune response after vaccination was tested by determination of anti-HAV with RIA and of neutralizing antibodies with an appropriate test system. Results showed that anti-HAV titers of 1:1,000 and greater, as well as neutralizing antibody titers of 1:1,000 and greater, were found in sera of animals vaccinated with different preparations. It became evident that good anti-HAV titers persisted over a period of at least 1.5 years in goats and mice after immunization with a semipurified HAV vaccine, and titers up to 1:200 were present in mice 2 years after vaccination with a highly purified HAV vaccine.

Animals↗
PubMed1987

Growth-inhibiting effect of crude pineal extracts on human melanoma cells in vitro is different from that of known synthetic pineal substances.

The effect was studied of a number of synthetic indoleamines, pteridines, beta-carbolines, of AVT and of crude extracts from rat and ovine pineal glands on human melanoma cells in vitro. The identified pineal substances as well as some of their analogues showed an inhibitory effect only at non-physiologically high concentrations. However, crude pineal extracts were more active than the synthetic pineal substances tested. They contain a compound which may have a tumor-inhibiting potency comparable to that of methotrexate but a different mechanism of action.

Animals↗
PubMed1987

Properties of a hepatitis A virus candidate vaccine strain.

This paper describes the biophysical and biochemical properties as well as electron microscopical studies of a candidate hepatitis A vaccine strain propagated in human fibroblast cells. Our results indicated that, in CsCl, the density of hepatitis A virus (HAV) from cell culture supernatant and of HAV extracted from infected cells was influenced by the quantity of lipid material associated with HAV. Antigenicity of untreated HAV, therefore, was detected primarily in low density CsCl fractions (1.11 g/ml, 1.21 g/ml). After lipid reduction with NP40 detergent or chloroform/Genetron, antigenicity and infectivity were primarily detected in high density CsCl fractions (1.31 g/ml). Electron microscopy demonstrated a strong association between membranous material and virus particles of low density in CsCl as well as virus-like particles in ultrathin sections of HAV-infected human fibroblast cells. The uncovered virus particles banded in the 1.31 g/ml dense CsCl fraction lacked lipid material. The s value was 79 for 1.19 g/ml to 1.22 g/ml dense HAV and 147 for 1.29 g/ml to 1.33 g/ml HAV. Autoradiography of the radioiodinated dense HAV revealed some proteins with high Mr (120K to 67K) and others with low Mr (37K to 15K).

Fibroblasts↗
PubMed1987

Inhibition of in vitro hematopoiesis by hepatitis A virus.

Inoculation of human bone marrow with hepatitis A virus (HAV) resulted in a dose- and duration-of-incubation-dependent suppression of hematopoietic progenitor (CFU-GM, BFU-E, CFU-Mix) growth in vitro. Monocytic progenitors appeared to be least affected. While HAV inactivation by heat or beta-propiolactone and neutralization by specific antibodies completely abrogated hematopoietic inhibition, depletion of adherent bone marrow cells, and enrichment of progenitors did not alter the pattern of suppression, which also seemed to be independent of HuIFN-alpha, -beta, -gamma, and TNF. These findings support the concept that direct infection of progenitor cells by HAV may be responsible for hematologic changes commonly seen during early phases of infectious hepatitis and possibly for some cases of bone marrow failure.

Adult↗
PubMed1987

Characterization of cell mediated immune responses to the hepatitis B core protein in man.

Eight donors immune to hepatitis B (HB) after natural infection were studied for their cell-mediated immune response to hepatitis B core (HBc) protein in vitro. Significant specific activation was observed in highly purified peripheral blood lymphocytes and T cells from these donors after 5-8 days of incubation with HBc protein. This in vitro response was modulated by monocytic cells and maximal 3H-thymidine incorporation was elicited with low concentrations of the antigen (0.1-10 ng/ml). The cell-mediated immune reactivity towards HBc-protein was significantly (P less than 0.005) elevated compared to the envelope material of the virus (HBsAg) when analysed in the same donor population. In contrast, donors with plasma-derived hepatitis B vaccine induced immunity to HB exhibited only specific lymphocyte activation to HBsAg. These data indicate that the composition of immune responses conferring protection against HBV after natural infection is far more complex than after immunization with the hepatitis B vaccine. Further characterization of the cell-mediated immune response to HBc protein and its relation to protection against HBV seems warranted when strategies for new HB-vaccines are being designed.

Adult↗
PubMed1986

Lack of complement-dependent cytolytic antibodies in hepatitis A virus infection.

Sera collected from patients with acute hepatitis A virus (HAV) infection and convalescent sera were examined for cytolytic activity against HAV-infected human-embryo lung fibroblasts (HAV carrier fibroblasts). Using the 51chromium release assay, no complement dependent antibody mediated cytolytic activity against HAV carrier cells could be detected. In control experiments with identical cell strains, anti-herpes simplex virus (HSV) positive sera and complement caused specific lysis of HSV type 1 infected target cells. The data presented here do not support the hypothesis that in the possible immunopathogenesis of HAV infection, complement-dependent cytolytic antibodies play an essential role.

Antigens, Surface↗
PubMed1986

Preliminary characterization of a fast-growing strain of human hepatitis A virus.

A fast-growing strain of Human Hepatitis A (HHA) virus was selected by progressively shortening by the time between serial passages of the isolate in the simian cell line Frp/3. The virus so selected infected 90-95% of the cells in 7-10 days, and developed a strong cytopathic effect (CPE). The synthesis of HHA-specific antigens and the CPE were neutralized simultaneously by standard anti-HHA sera. This fast-growing strain has the characteristics of a picornavirus.

Animals↗
PubMed1984

Hepatitis A-virus in cell culture. V. Neutralizing antibodies against hepatitis A-virus.

A test system for the detection of neutralizing antibodies against hepatitis A-virus (anti-HAV-Nt) is presented. The anti-HAV-Nt assay is performed with Frhk-4/R cells and the hepatitis A virus (HAV) strain GBM/Frhk-4/R which has been adapted to these cells. Non-neutralized HAV is demonstrated 14 days after infection of Frhk-4/R cells using a radio-immunoassay for detecting newly grown HAV. The influence of differing amounts of HAV on the anti-HAV-Nt titre and the effect of variations in incubation time of virus-serum mixtures are described. The time course of anti-HAV-Nt is shown in sera from a hepatitis-A patient which were taken at different stages of the disease. Anti-HAV-Nt is compared with anti-HAV and anti-HAV-IgM. It is shown that anti-HAV-Nt correlates closely with anti-HAV and separated anti-HAV-IgG, but only slightly with anti-HAV-IgM. The test system presented makes possible the demonstration of neutralizing antibodies against HAV in gamma-globulin preparations and during vaccination studies.

Animals↗
PubMed1984

Hepatitis A-virus in cell culture. IV. Comparison of cell-culture-produced HAV with stool-derived HAV in diagnostic test systems.

Hepatitis A-virus produced in Frhk-4/R cells is used and compared with stool-derived HAV as an antigen in diagnostic test systems. It is shown that the two antigens react identically in the anti-HAV test with anti-HAV-IgG positive human sera. In the anti-HAV-IgM test, too, stool-derived HAV and cell-culture-produced HAV react very similarly. The titres of anti-HAV-IgG and anti-HAV-IgM positive sera, obtained with stool and cell-culture HAV in quantitative antibody determinations, are shown to be identical. It is shown that the problem of HAV antigen production can now be solved by propagation of HAV with Frhk-4/R cells and that this antigen is very useful in diagnostic test systems.

Animals↗
PubMed1984

Adsorption properties of different hepatitis B virus related antigens (HBsAg, HBcAg, HBeAg) on octanohydrazide-Sepharose 4B.

Chromatography of plasma containing hepatitis B virus and partially purified viral antigens on a hydrophobic gel derivative (octanohydrazide-Sepharose 4B) revealed that HbsAg and HbcAg were adsorbed to the gel in 0.75 mol/l ammonium bicarbonate and eluted by a detergent, Berol. HBeAg in a purified HBcAg preparation from human liver, but not HBeAg in plasma, was bound to the gel. Furthermore, HBeAg in the HBcAg preparation, but not HBeAg in plasma, lost its antigenic reactivity in the presence of Berol, indicating that the two HBeAgs were present in different molecular configurations. However, HBeAg could be released from HBV (HBcAg) and form a component which sedimented slowly and was immune-reactive in the presence of the detergent. The results contribute to knowledge of the interrelationship between hepatitis B-related antigens and indicate that chromatography on hydrophobic gel derivatives can be used not only for the purification (and removal) of HBsAg but also of HBcAg.

Adsorption↗
PubMed1984

A comparison of enzyme-immunoassay and radioimmunoassay for detection of hepatitis A virus and antibodies against hepatitis A virus.

A direct comparison has been made of tracers labelled with an enzyme and with 125I in solid phase enzyme-immunoassay (EIA) and solid phase radioimmunoassay (RIA) for the detection of hepatitis A virus (HAV) antigen and antibodies to HAV. By comparing the binding capacity of peroxidase-labelled anti-HAV-IgG and anti-HAV-F(ab)2 fragments tracers, anti-HAV-IgG was found to have a higher binding capacity than anti-HAV-F(ab)2 fragments in both EIA and RIA. For EIA 16.25-fold more anti-HAV-IgG was needed for one test probe compared to RIA and 32.5-fold more anti-HAV-F(ab)2 fragments. For the detection of HAV antigen from stool preparations and IgG and IgM antibodies against HAV, there were only minor quantitative differences in titre. EIA was as sensitive as RIA.

Antibodies, Viral↗