Biomedical subjects

E G Wright

Publications and source records attributed to E G Wright.

93 records · Page 6Linked to original sources

PubMed1976

Inhibitor of stem cell proliferation in normal bone marrow.

A saline extract from normal bone marrow cells having a molecular weight in the range 50000-1000000 daltons has been found to protect rapidly proliferating haemopoietic spleen colony forming cells (CFUs) from the lethal effects of large doses of tritiated thymidine. This extract is non-toxic to the cells. It is not found in regenerating marrow where the CFUs population is rapidly proliferating. Its effect appears to be specific for the CFUs since it has no effect on the proliferation of its close descendant, the granulocytic precursor cell (CFUc), and no effect on the average cytoplasmic structuredness of the whole bone marrow cell population. The active material is probably protein since it is degraded by trypsin.

Animals↗

PubMedDate not supplied

Inducible genomic instability: new insights into the biological effects of ionizing radiation.

The biological consequences of exposure to ionizing radiation include gene mutation, chromosome aberrations, malignant transformation and cell death. These effects are attributed to the production of irreversible damage at the time of the irradiation. However, there is now considerable evidence that cells that have survived irradiation may produce descendants in which a high frequency of de novo chromosome aberrations and gene mutations arise or in which there is an enhanced death rate. These delayed effects are manifestations of an induced genomic instability. All the various delayed effects are induced at very high frequency and are unlikely to be due to conventional mutational changes. At present little is understood of the processes involved in the initiation of inducible instabilities and in the maintenance and transmission of the phenotype over many generations of cell replication. However, it is becoming evident that the expression of inducible instability has a strong dependence on the type of radiation exposure, the cell type irradiated and the 'genetic predisposition' of the irradiated cell. Radiation-induced genomic instability presents a major challenge to conventional radiobiology concepts and has important implications for mechanistic studies of radiation action particularly in the context of radiogenic malignancy.

Animals↗

PubMedDate not supplied

Production of stem cell proliferation stimulators and inhibitors by haemopoietic cell suspensions.

In mice treated with phenylhydrazine haemopoietic spleen colony forming cells (CFU-S) are proliferating rapidly in the bone marrow but not in the spleen. Using such mice we have investigated the production of factors responsible for the control of CFU-S proliferation. When irradiated spleen cells are incubated with non-irradiated bone marrow cells there is a marked fall in the proportion of femoral CFU-S in DNA synthesis. In the converse experiments, rapid triggering of splenic CFU-S is achieved. Both these effects can be eliminated by washing the irradiated cells prior to incubation; they are, however, retained in the supernatant media "conditioned" by these cells. When the washed cells are incubated in fresh medium at 37 degrees C both stimulatory and inhibitory activities reappear but after different incubation periods. The data demonstrate that both proliferation stimulatory and inhibitory factors acting on CFU-S can be produced by the same haemopoietic cell suspension.

Animals↗