Biomedical subjects

R Geller

Publications and source records attributed to R Geller.

29 records · Page 2Linked to original sources

PubMed1978

Significance of the cell cycle in commitment of murine erythroleukemia cells to erythroid differentiation.

The relationship between differentiation of murine erythroleukemia cells (MEL) induced by DMSO and the cell division cycle has been analyzed. We demonstrate that incubation in the presence of DMSO increases the length of the G1 phase of the cell cycle. A method of synchronization of MEL cells by unit gravity sedimentation has been developed and characterized. Using this method, a series of synchronized cell populations covering the entire cell division cycle can be generated simultaneously. Cells synchronized by this technique were challenged with DMSO and analyzed for kinetics of commitment to the differentiation program. Our results indicate that populations of cells in G1 or G2 at the time of addition of inducer give rise to a greater proportion of committed cells than an unfractionated population, while cells in S phase result in a lower percentage of committed cells than the unfractionated population when cultured in DMSO.

Animals↗

PubMed1977

Anemia in primary hyperparathyroidism.

Although anemia has not been widely appreciated as a complication of primary hyperparathyroidism, 5.1% of the individuals with this disorder seen at the Massachusetts General Hospital since 1962 had a normochromic, normocytic anemia that could not be related to blood loss,a deficiency state, or uremia. The anemic group had more advanced bone disease and higher levels of serum calcium, alkaline phosphatase, and parathyroid hormone than the nonanemic group. Results of bone marrow biopsies performed in five patients showed variable degrees of myelofibrosis. However, none of the patients had hepatosplenomegaly, a myelophthisic peripheral blood smear, leukopenia, or thrombocytopenia. Removal of the abnormal parathyroid glands led to improvement or correction of the anemia.

Adolescent↗

PubMed1976

Commitment to erythroid differentiation by friend erythroleukemia cells: a stochastic analysis.

A method for the clonal analysis of murine erythroleukemia cells has been developed which allows the precise characterization of the number of progeny produced by each cell and the degree of differentiation of each progeny cell. The potential of almost every cell in the culture can be monitored because a plating efficiency close to 100% has been achieved. The effects of treatment with an inducer of differentiation (DMSO) on the proliferative capacity of the treated cells have been studied with this technique. Cells from a mass culture treated with inducer give rise to colonies of differentiated progeny when subsequently cloned in the absence of inducer. Colonies exhibiting this phenotype represent the progeny of cells committed to the differentiation pathway by treatment with inducer. We observe that the commitment decision limits the subsequent proliferative capacity of the cell to four additional cell divisions. A quantitative analysis suggests that the commitment decision for each cell is made in a stochastic manner. Irreversible commitment to the expression of differentiated functions occurs with discrete probability per cell generation for many cell generations. The value for this probability is a function of the concentration of inducer (DMSO). A correlative biochemical study suggests that an irreversible commitment decision by a significant proportion of the population precedes or accompanies increases in cytoplasmic globin mRNA levels, one of the earliest detectable biochemical markers for erythroid differentiation in this system. A specific kinetic model based on these considerations has been developed to predict clonal phenotypes as a function of time and probability of commitment. Quantitative predictions based on this model are in excellent agreement with experimental observations. The effectiveness of a stochastic model in predicting the behavior of this system is discussed in relation to the stochastic behavior of normal hematopoiesis and the biochemical mechanisms which control these differentiation programs.

Cell Division↗

PubMed1974