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D Zipori

Publications and source records attributed to D Zipori.

83 records · Page 5Linked to original sources
PubMed1979

Changes in the fibroblastoid colony forming unit population from mouse bone marrow in early stages of Soule virus induced murine leukemia.

Fibroblastoid cells from mouse bone marrow belong to the hemopoietic inductive microenvironment involved in the regulation of hemopoiesis (1). We observed a decline in the incidence of precursors of these cells (fibroblastoid colony forming units) in the early stages of viral leukemogenesis. This was not accompanied by similar changes in bone marrow derived hemopoietic colony forming cell populations (CFU-s and CFU-c). Cultured fibroblastoid colonies from the bone marrow of young AKR mice or Soule murine leukemia virus inoculated BALB/c mice were found to produce type-C ecotropic virus. No such production was observed when similarly cultured granulocyte macrophage colonies (CFU-c) from the bone marrow of these mice were examined. The possibility that the fibroblastoid cell population is a major source of ecotropic leukemia viruses in the early stages of viral leukemogenesis is discussed.

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PubMed1979

The role of fibroblastoid cells and macrophages from mouse bone marrow in the in vitro growth promotion of haemopoietic tumour cells.

Adherent cells from mouse bone marrow have been shown to promote the in vitro growth of the AVRij-1 tumour cell line. The experiments presented here suggest that the adherent cells involved in this phenomenon are the progeny of bone marrow derived fibroblastoid colony forming units. The latter were characterized by means of cell density distribution analysis. They had a broad distribution pattern and an average peak cell density of 1.069 g.cm-3. The growth promotion activity exerted by adherent cell layers from the various density fractions on the AVRij-1 tumour cell line coincided with the distribution of fibroblastoid colony forming units. On the other hand, the presence of macrophages in the adherent layers seemed to be non-essential for the in vitro promotion of growth of the AVRij-1 cell line.

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PubMed1975

Recent studies on the role of the thymus in early stages of lymphopoiesis and immune differentiation.

The influence of thymus deprivation and thymus restoration was studied: a) on the cycling capacity of colony forming cells (CFU-S) in the bone marrow and b) on the establishment of tolerance in liver radiation chimeras. After neonatal thymectomy a reduction in the number of CFU-S in the bone marrow was observed. This reduction was accompanied by a striking decrease in the proportion of cycling cells in the bone marrow of thymus deprived mice. On the other hand, restoration of thymus function by thymic hormone (THF), by implantation of thymus in semi-impermeable cellophane bags, or by pregnancy, raised the number of cycling cells in the bone marrow to that of normal controls. Parental embryonic liver cells reconstitute lethally irradiated mice, and permit establishment of tolerance to further challenges of immunocompetent cells syngeneic to liver donors. We found here that adult thymectomy prevents the establishment of permanent tolerance in liver chimeras. Again, restoration of thymic function by THF permitted liver chimeric mice to resist the immunologic attack of parental spleen lymphocytes syngeneic to donor liver cells.

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PubMed1975

Impaired radioprotective capacity and reduced proliferative rate of bone marrow from neonatally thymectomized mice;.

The colony forming capacity of bone marrow from neonatally thymectomized mice is reduced in comparison with that of normal animalsmin addition to this quantitative change, we observed that the bone marrow of thymectomized animals has a reduced radioprotective effect upon inoculation into lethally irradiated recipient mice. It was also found that the cellularity of spleen colonies derived from bone marrow of thymectomized animals is lower than that of intact controls. In vitro uptake of 3H-thymidine into cells of spleen colonies, and rate of DNA synthesis measured in vitro were found to be reduced in cells derived from bone marrow of thymectomized donors; The initially observed reduction in colony forming capactiy of bone marrow from neonatally thymectomized mice could be reversed by thymus reimplantation=

Animals↗
PubMed1975

The role of a thymus humoral factor in the proliferation of bone marrow CFU-S from thymectomized mice.

The colony forming capacity of bone marrow cells from thymectomized mice was shown to be reduced as compared to that of bone marrow cells from normal donors. A further indication of changes in the proliferative capacity of colony forming cells (CFU-S), following thymectomy, was given by examination of the sensitivity of these cells to chlorambucil and by 3H-thymidine 'suicide' experiments; both showed that CFU-S from thymectomized mice were not cycling at the same rate as normals. It was also found that in late pregnancy of thymectomized females, there is an elevation in the number of bone marrow CFU-S and an increase in cell cycling. Such an increase could also be achieved by implantation, into thymectomized mice, of thymus lobes in closed diffusion chambers. Finally, in vitro administration of a thymus hormone (THF) reversed the suppressive effect of thymectomy on DNA synthesis in bone marrow CFU-S. Since the action of THF was restricted to bone marrow cells of thymectomized mice it is plausible that normal bone marrow contains at least two subpopulations of CFU-S, one of which is dependent upon a humoral product of the thymus.

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