Current development of the human and environmental contamination in the Bryansk-Gomel Spot after the Chernobyl accident.

Up to 1991, it was assumed that after the Chernobyl accident in 1986 the time development of radioactive contamination with regard to environment, foodstuff, and man would decrease due to migration processes in the soil, radioactive decay, and protective measures. This assumption was confirmed by all measurements in the first few years after the accident. Since 1991, however, a change in this development has been observed, as many measurements show stagnation or in some cases even an increase of foodstuff and human contamination. If normalised to an average local ground contamination, only a few groups of foodstuffs (e.g., potatoes) show a slight decrease in radioactivity. In this paper, the time development of radioactive contamination in the Bryansk-Gomel Spot on the basis of measurements since 1991 is presented. The consequences for long-term dose assessment are discussed.

Fibronectin increases both non-adherent cells and CFU-GM while collagen increases adherent cells in human normal long-term bone marrow cultures.

Normal haematopoietic proliferation and differentiation occur within the human bone marrow microenvironment which is comprised of stromal cells including fibroblasts, adipocytes, macrophages and endothelial cells as well as the extracellular matrix made of collagen, fibronectin, laminin, vitronectin, thrombospondin and haemonectin. All haematopoietic progenitor cells including primitive LTC-IC, multilineage CFU-mix, myeloid CFU-GM and erythroid BFU-E adhere to the heparin-binding domains of the extracellular matrix component fibronectin. Human long-term bone marrow cultures (LTHBMC) represent the best available approximation for the in vivo marrow microenvironment in which the proliferation and differentiation of haematopoietic progenitor cells depend on the presence of marrow stromal cells and their attendant matrices. Since extracellular matrix components have been shown to promote myelopoiesis in long-term murine bone marrow cultures, we have examined the effect of two main components of the extracellular matrix: fibronectin and collagen type I on myelopoiesis in LTHBMC in an effort to increase the myeloid progenitor cell production. The present study revealed different modulatory effects for these two components. Collagen significantly increased the adherent fraction of LTHBMC (p < 0.05) but always resulted in a decreased myeloid progenitor cell (CFU-GM) production throughout the whole 8 weeks of culture. On the other hand, fibronectin significantly increased the number of both non-adherent cells. CFU-GMs (p < 0.01) and to a lesser extent the number of adherent cells as well as maintaining the LTHBMC up to 14 weeks. Fibronectin has been previously shown to stimulate the development of CFU-GMs in short-term semisolid cultures and to play an active role in haematopoietic progenitor cell-microenvironment interactions. Therefore, the presence of fibronectin in LTHBMC could increase both the productivity and longevity of myelopoiesis in the system. The integration of fibronectin in the ex vivo expansion systems currently undergoing development would ensure a sustained effective cumulative production of the myeloid progenitor cells (CFU-GMs), and consequently could accelerate the rate of haematological recovery in transplanted patients.

Mitogenic activity of high molecular polysaccharide fractions isolated from the cuppressaceae Thuja occidentalis L. enhanced cytokine-production by thyapolysaccharide, g-fraction (TPSg).

Thuja polysaccharide g fraction (TPSg) was shown to be an inducer of the CD4+ fraction of the human peripheral blood T-cell subset (1,2). Furthermore, it could be demonstrated that TPSg is a potent inhibitor of the expression of HIV-1-specific antigens and of the HIV-1-specific reverse transcriptase (3). This report deals with the cytokine pattern induced by TPSg in human peripheral blood lymphocyte (PBL) and purified monocyte/macrophage cultures. In addition, a further characterization of the CD4+ T-cell fraction stimulated by TPSg was performed by FACS analysis. TPSg is induces IL-1 beta, IL-2, IL-3, IL-6, gamma-IFN, G-CSF, GM-CSF, and TNF-beta production in PBL cultures; and IL-1 beta and IL-6 in monocyte/macrophage cultures. Enzyme-linked immunosorbent assays (ELISAs) demonstrated that no IL-4 was produced by PBL cultures under TPSg influence.

Mechanisms contributing to the virus persistence in Aleutian disease.

In this review published results and further studies concerning the persistence of Aleutian disease virus (ADV) isolate SL3 are presented. By Southern blot and in situ hybridization with strand-specific RNA probes focal replication of ADV-DNA was demonstrated in spleen, mesenteric lymph nodes, sporadically in mononuclear cells of the peripheral blood and bone marrow cells. These findings further support the concept of the lymphotropism of ADV. All cell culture-adapted ADV strains appear to have a ts-defect. Our in vitro studies indicate that the ADV isolate G(orham) induced the synthesis of comparable amounts of viral replicative DNA and viral proteins VP1 and VP2 at the non-permissive temperature of 37 degrees C. However, the viral progeny DNA synthesis was about threefold less at 37 degrees C compared to the permissive temperature of 32 degrees C. These findings suggest that the reduced level of viral progeny DNA at 37 degrees C accounts for the reduced production of infectious ADV. Finally, we provided experimental evidence that the apparent lack of neutralizing antibodies in AD is due to the masking of critical viral epitopes by cellular phospholipids.

Mitogenic activity of high molecular polysaccharide fractions isolated from the Cupressaceae Thuja occidentale L. I. Macrophage-dependent induction of CD-4-positive T-helper (Th+) lymphocytes.

The arborvitae or Thuja occidentale L., one of the Cupressaceae, has rarely been investigated until now. Several authors have demonstrated that allopathic extracts of this plant could be used as strong antiviral agents directed against plant and animal viruses. Polysaccharide fractions with molecular weights ranging between 20,000 and 1,000,000 and higher have been isolated from the aqueous alkaline extract of the herbal parts of T. occidentale L. by ethanol precipitation and fractionation by ultrafiltration. High molecular subfractions of Thujapolysaccharides (TPS) proved to be highly mitogenic on peripheral blood leukocytes. It was demonstrated by the alcalic immune phosphatase-antiphosphatase and Pappenheim staining methods that the mitogenic and cluster-forming activity of TPS cause T cell induction, in particular, of CD 4-positive T-helper/inducer cells as opposed to B cells. The CD-4+ T-helper/inducer cell induction is connected to an increased production of IL-2. The cluster-forming ability and mitogenity of TPS correlates well with the 3H-thymidine uptake and seems to be IL-1 and IFN-gamma dependent as could be shown by blocking the mitogenic effect using anti-IL-1- and anti-IFN antibodies. Whether it is possible to use these polysaccharide fractions as an adjuvant in the therapy of immune deficiency syndromes and cancer must now be further investigated.

Premature labor contractions and the value of serum ferritin during pregnancy.

In general, the diagnosis of pregnancy-related anemia relies on the estimation of the hemoglobin level. The findings of this study suggest that the additional estimation of serum ferritin - a reliable index of the iron stores - can improve the diagnosis of anemia. Hematological data of 150 pregnant women were retrospectively related to the courses of pregnancy, in particular to the incidence of premature labor contractions. 70% of the pregnant women included in the investigation had a serum ferritin value below 20 micrograms/l and thus iron deficiency. If the hemoglobin value alone had been estimated, 50.6% of the women with iron deficiency (serum ferritin less than 20 micrograms/l) would not have been detected among those pregnant women with a hemoglobin value of more than 11 g/dl. These findings are also of particular relevance as a significant correlation has been found between the incidence of premature labor contractions and the serum ferritin level: only 11% of the pregnant women investigated whose serum ferritin values exceeded 20 micrograms/l had premature labor contractions, whereas premature labor was recorded in 48% of the pregnant women with serum ferritin values below 10 micrograms/l.

Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice.

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c, DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.

Epitopic mapping of structural and nonstructural Aleutian disease virus proteins.

Common antigenic properties for p85 and p75 but a different antigenic character for p71 Aleutian disease virus (ADV) proteins were demonstrated by Western blot analysis with monoclonal antibodies. It was shown that four hybridomas (ADV-Hy 47, 66, 77 and 84) with specific reactivity for structural proteins p85 and p75 also recognized p25 but not the p71, nonstructural, protein. In turn, the monoclonal antibody ADV-Hy 2 recognized the p71 protein only. For further studies of their antigenic properties, the ADV proteins were subjected to enzymatic or chemical cleavage. The derived peptide fragments were analyzed by epitopic mapping. Depending on the cleavage reagent and monoclonal antibody applied, specific peptide maps were revealed. The maps of p85 and p75 were very similar, indicating that both proteins shared an extensive antigenic relationship. After cleavage with alpha-chymotrypsin and N-chlorosuccinimide and by using the ADV-Hy 84 monoclonal antibody, unique peptide fragments were identified with p85 which had no counterparts in p75 fragments.

Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice.

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c, DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.

Sequential studies of bovine leukemia virus antibody development in dairy cattle over a four-year period.

Serological examinations using the agar gel immunodiffusion and immunofluorescence tests were undertaken to study: a) the development of bovine leukemia virus infections in a given herd under field conditions monitored by antibody development, b) the reproducibility of the results of serological examination during 22 sequential tests, c) the antibody titre variations amongst individual animals. A total of 286 Friesian cattle representing 2,352 serum samples was tested at regular intervals over a period from 1974/75 to 1978. The percentage of animals with bovine leukemia virus antibodies continuously increased during the observation period from an initial 4.8% (1974/75), 9.7% (1976), 34.2% (1977) to 52.6% (1978). On the basis of 22 sequential tests representing 1,672 serum samples obtained from 76 animals no false positive reactions were seen in the immunodiffusion test. Thirty-six (14.2%) out of 254 animals, however, showed variations of the antibody titre leading to a shift from positive to negative or negative to positive results, respectively. AnothFr three cattle (1.2%) shifted from a positive to negative immunodiffusion result and maintained their negative reactivity for at least two following tests. But they still had specific antibodies if tested by the immunofluorescence test. A detailed analysis of the group of variable reactors supports the view that a more sensitive and quantitative test system may be helpful to complement the presently used immunodiffusion test for the eradication of enzootic bovine leukosis.