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R Neth

Publications and source records attributed to R Neth.

At least 19 recordsLinked to original sources
PubMed1990

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.

Aleutian Mink Disease↗
PubMed1986

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.

Animals↗
PubMed1986

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.

Aleutian Mink Disease Virus↗
PubMed1985

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.

Animals↗
PubMed1978

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.

Animals↗
PubMed1976

Cytologie and cytochemistry of colony cells in soft agar gel culture from normal and leukemic bone marrow.

In order to judge differentiation of cells in soft agar colonies, cytological and cytochemical classification of single cells within these colonies is necessary. In this study, 1,026 colonies from 15 normal and 95 leukemic bone marrows have been evaluated using cytological, cytochemical, and immunocytochemical techniques. In 180 colonies from 15 normal controls no segmented neutrophils have been observed. The colonies mostly consisted of monocytes and macrophages, rarely pure eosinophil colonies were observed. The number of monocyte/macrophage colonies in untreated AML and the percentage of pure eosinophil colonies in AML and ALL in remission are reduced, as compared to normal controls. In 174 colonies from a total of 926 colonies derived from bone marrows of leukemic patients, plasma cells and in 20 colonies, blast cells have been observed. In contrast to normal colonies, growth of colonies containing blast cells does not depend upon the conditioned medium of the leukocyte feederlayer. This investigation has demonstrated the necessity of cytological and cytochemical classification in addition to quantiative evaluation of soft agar colonies when studying the effect of factors on proliferation and differentiation of normal and leukemic stem cells.

Bone Marrow Cells↗
PubMed1975

[The effect of actinomycin d, acridine dyes and related substances on the biosynthesis of nucleic acids in normal and leukemic white blood cells. Comparative investigation in intact cells and in a cell-free system (author's transl)].

Acridine dyes inhibit the incorporation of 3H-thymidine and 3H-uridine in intact cells to the same extent as Actinomycin D. In contrast to Actinomycin D, RNA synthesis by DNA - dependent RNA polymerase in a cell-free system is inhibited at lo2 higher concentrations of acridine dyes, only. Possible differential effects on the cell membrane resulting in decreased intracellular pools of uridine and thymidine are discussed.

Acridines↗