Biomedical subjects
Publications and source records attributed to H Jackson.
Pleomorphism of Cellulomonas acidula in liquid and on solid media is described. Growth in liquid medium is characterized initially by the formation of club-shaped rods and later by cocci. On solid media the organism formed irregular branched cells and large swollen cells.
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Murine pluripotent hematopoietic stem cells and precursor cells with restricted commitment to erythrocytes, granulocytes and macrophages as well as megakaryocytes have been purified 30- to 50-fold from mouse bone marrow cells. Purification was achieved by a three-step procedure. Bone marrow cell populations free of erythroid cells and lymphocytes were obtained by culturing the cells for several weeks. Macrophages and adherent polymorphic neutrophils (PMN) were removed by adherence to plastic. The remainder of the PMN along with more primitive granulocytes (but not promyelocytes and some monocytoid cells) were removed either by neutral density centrifugation or by differential centrifugation after rosette formation with sheep erythrocytes coated with immunoglobulin (EA rosettes). The remaining population of marrow-derived cells contained 40-66% blast cells, 20-35% promyelocytes and 5-10% other cells (usually PMNs and monocytes). Using cloning techniques to detect immature hemopoietic cells, this population contained 15-35% granulocyte-macrophage progenitor cells, approximately 0.2% erythroid burst-forming cells, approximately 0.1% megakaryocyte progenitor cells and 1-3% pluripotent stem cells (based on seeding efficiency 0.06).
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The phosphate esters of racemic (+/-) alpha-chlorohydrin and its S(+)-optical isomer have been prepared as cyclohexylamine salts. In vitro both inhibited glyceraldehyde-3-phosphate dehydrogenase by a competitive mechanism, whereas (+/-) alpha-chlorohydrin did not. The S(+)-isomer was approximately four times as potent as the racemate. These results correlate with data concerning the relative contraceptive activity in rats of racemic and S(+) alpha-chlorohydrin. They support the view that the antifertility mechanism involves in vivo formation of S(+) alpha-chlorohydrin-1-phosphate, with resulting inhibition of glycolysis in sperm.
Megakaryocytes and their precursor cells were sustained in mouse bone marrow suspension cultures for over 4-6 wk. Megakaryocyte precursor cells were detected by their capacity to form colonies of megakaryocytes in semisolid agar cultures. Colony formation was dependent on the presence of medium conditioned by a myelomonocytic leukemic cell line (WEHI-3CM). Megakaryocytes from the liquid and semisolid cultures were identified by cytoplasmic acetylcholine esterase and by ultrastructural analysis. The suspension medium from the bone marrow liquid cultures which sustained megakaryopoiesis was not directly acitive in stimulating megakaryocyte colony formation in the semisolid agar cultures, but potentiated the number of colonies detected when WEHI-3CM was present. Bone marrow-conditioned medium increased the sensitivity of megakaryocyte progenitor cells to the stimulus in WEHI-3CM. Addition of the activities present in the two sources produced a quantitative assay for the detection of mouse megakaryocyte progenitor cells. These studies showed: (1) that no inductive regulator of in vitro clones of megakaryocytes was present in the supernatants from the long-term marrow cultures and, (2) that at least two factors were necessary for the induction of megakaryocyte progenitors to proliferate and differentiate in semisolid cultures in vitro.
The extent to which mouse megakaryocyte progenitor cells (colony-forming unit-megakaryocyte, CFU-M) can proliferate in semisolid cultures prior to endomitosis, and conditions that may regulate that differentiation step, were investigated. The proliferative capacity of CFU-M was determined by estimating the number of megakaryocytes per colony. A bimodal distribution was observed (modal values, 10-15 and 25-30 cells/colony), indicating that separate megakaryocyte progenitor cells may be biased in their capacity for proliferation versus endomitosis. Differences were observed in the cell cycle characteristics of CFU-M as determined in vivo and in vitro that suggest that maturation of CFU-M into megakaryocytes may be regulated within the marrow by control of the cell cycle of the megakaryocyte precursor cell.
Modified conditions are reported for successful continuous bone marrow cultures with stem cell self-renewal and granulocyte-macrophage differentiation. Cells cultured over several weeks were found to be identical to freshly isolated bone marrow cells. Polymorphic neutrophils derived from cultures and primary bone marrow neutrophils both showed C3 AND IgG receptors and both actively phagocytosed foreign particles. Cultured and normal CFU-c were identical, both in their dose responsiveness to CFS and in their sedimentation rate characteristics.
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Granulocyte and macrophage progenitor cells which clone in semi-solid agar cultures were characerized by separating murine bone marrow cells by equilibrium density centrifugation. These in vitro colony forming cells (CFU-c), when induced by stimuli in mouse lung-conditioned medium, were found to be heterogeneous in their density properties. Differences were found in the dose responsiveness of two major subpopulations of these progenitor cells. One population (modal density 1.074 gcm-3) responded in an identical manner to stimuli present in mouse lung-conditioned medium and pregnant mouse uterus extract. A second population (modal density 1.070 gcm-3) was found to be markedly different in its dose responsiveness to mouse lung-conditioned medium, from the other subset (1.074 gcm-3). The cloning of the low density progenitor cells and the observed dose responsiveness was found to correlate with an activity present in a stimulus in mouse lung-conditioned medium but was not identical to the stimulus in pregnant mouse uterus extract. No subpopulation, however, gave exclusively granulocyte or macrophage colonies.
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