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Biomedical subjects

T N Fredrickson

Publications and source records attributed to T N Fredrickson.

At least 91 records · Page 5Linked to original sources
PubMed1976

Diffusion chamber hematopoiesis in marrow and spleen cells from mice infected with Rauscher leukemia virus (RLV-A).

Preleukemic and terminal phase marrow cells from RLV-A-infected mice placed within diffusion chambers and implanted into normal mice, maintained elevated levels of both erythroid and myeloid precursor cells, whereas normal control marrow cells grown within diffusion chambers in normal hosts did not. Splenic tissue from preleukemic and terminal mice when placed as a cellular suspension into diffusion chambers and implanted into normal recipients also maintained high erythroblast numbers. However, while some transient growth of myeloid precursor elements occurred in preleukemic spleen cultures, terminal spleen cultures displayed essentially no granulocytic precursor cell growth. In control spleen cultures, erythropoiesis and granulocytic precursor cell numbers were reduced to nondetectable levels after 4 days of culture.

Animals↗
PubMed1975

Morphogenesis of marek's disease virus in feather follicle epithelium.

Three evaluative systems, immunodiffusion, fluorescent antibody (FA), and electron microscopy (EM), were used to follow the morphogenesis of Marek's disease virus in inoculated chickens. Of the three, EM and FA were the most sensitive in detecting early stages of infection. Virus particles were found in skin biopsy specimens as early as 12 days post inoculation. Immature naked particles appeared first in the nucleus; later particles were enveloped in the cytoplasm and enclosed in cytoplasmic inclusion bodies. No evidence for continued virus replication was seen in feather follicles after an initial burst of heavy virus production, which lasted several weeks. Residual virus, however, was found occasionally in cytoplasmic inclusion bodies within keratinized material near the feathers. This was believed to contribute to the long-term shedding of infectious virus into the environment.

Animals↗
PubMed1975

Granulopoiesis in "preleukemic" mice with anemia induced by Rauscher leukemia virus, variant a.

To understand further the hematopoietic dyscrasias induced by a variant (a) of Rauscher leukemia virus (RLV), we used Escherichia coli endotoxin to stress the hematopoietic system of control and RLV/a-infected BALB/c mice. During the preleukemic stages of virus infection, there was slight splenomegaly without peripheral blood erythroblastosis. Granulocyte release and tissue mobilization mechanisms appeared unaffected by the RLV/a infection. Both RLV/a-infected and control mice reacted to endotoxin with peripheral granulocytosis and peritoneal granulocyte mobilization, though the circulating granulocyte levels in RLV/a-treated mice initially were lower than those in controls. Spleen of RLV/a-infected animals were larger than those of controls, but both responded to endotoxin with elevated numbers of granulocytes and erythroblasts. Since numbers of bone marrow erythroblasts in both groups of mice were decreased after endotoxin, stem cell competition and/or shunting of stem cells from marrow to spleen may have been involved. Endotoxin also induced rapid falls in hematocrit levels in both groups. These studies suggested that RLV/a-infected mice can be a model to study 1) erythropoietic dysfunction uncomplicated by defective granulopoietic release and tissue mobilization control mechanisms, and 2) progression of evolving granulocytic leukemia.

Anemia↗
PubMed1975

Stimulation of erythropoietic differentiation in BALB/c mice infected with Rauscher leukemia virus.

The function of phenylhydrazine (PHZ) hemolysis in ameliorating the anemia induced in mice by a slow-acting strain of Rauscher leukemia virus (RLV-A) was described. After cessation of treatment with PHZ, mid-stage RLV-A-infected, anemic mice responded with massive reticulocytoses and a rebound in hematocrit above control levels. RLV-infected mice, subjected to PHZ-induced hemolysis or phlebotomy, produced high levels of plasma erythropoietin (Ep); this suggested that Ep mediated the PHZ-induced differentiation. In addition, administration of exogenous Ep induced a wave of erythroid maturation in RLV-infected anemic mice, which indicated that virus-infected erythroid precursors could still respond to the hormone governing normal differentiation.

Anemia↗
PubMed1975

Marek's disease in immunosuppressed chickens: growth of a transplantable lymphoma and development of the disease by natural exposure.

Evidence indicated that treatment of chickens with Cytoxan at hatching (bursectomy) had little effect on the development of transplantable Marek's disease (md) lymphoma. Cytoxan treatment of chickens at 2 and 3 weeks of age, however, apparently reduced the incidence of visceral tumors in chickens naturally exposed to MD. Amelioration of MD in immunosuppressed chickens was possibly mediated through suppression of MD-induced T-cell proliferation.

Age Factors↗
PubMed1973

Neutralization studies with Marek's disease virus and turkey herpesvirus.

Use of Marek's disease virus (MDV) in a neutralization test presents several problems, which are described, making this potentially useful test difficult. To obviate these difficulties, a plaque reduction test has been designed based on cross-neutralization of turkey herpesvirus (HVT) by serum-neutralizing MDV. The technique for such a neutralization test is outlined. Kinetics of development of neutralizing antibodies in chickens inoculated with HVT and MDV are described. The neutralization test can be used to evaluate viability of HVT vaccines and the possible role of neutralizing antibodies in the protection afforded by vaccination against MDV-induced tumors.

Animals↗