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Biomedical subjects

M C Williamson

Publications and source records attributed to M C Williamson.

5 recordsLinked to original sources
PubMed1995

In vitro effects of growth factors and dexamethasone on rat marrow stromal cells.

Bone marrow contains multipotential stromal stem cells that can differentiate into fibroblastic, osteogenic, adipocytic, and other cell lines. There is evidence for a considerable degree of plasticity in the differentiation of these different marrow stromal lines. Additional studies have been undertaken investigating the effects of basic fibroblastic growth factor (bFGF), transforming growth factor beta (TGF beta), and dexamethasone on the proliferation and differentiation of rat marrow stromal cells in in vitro cultures. Cell proliferation was stimulated by bFGF and inhibited by dexamethasone and TGF beta. Alkaline phosphatase activity was stimulated by TGF beta and dexamethasone, whereas the expression of the enzyme was inhibited by bFGF. Adipogenesis was induced in cultures containing dexamethasone, but this was depressed by the presence of TGF beta. These observations support the authors' previous hypothesis that there may be an inverse relationship between the differentiation of osteogenic and adipocytic cell lines. The results are relevant to osteoporosis and the aging skeleton, where excess marrow fat is a common feature, and have implications for the pathology of bone and marrow.

Alkaline Phosphatase↗
PubMed1986

Kinetics and differentiation of marrow stromal cells in diffusion chambers in vivo.

Rabbit marrow cells inoculated into diffusion chambers (10(7) cells/chamber) were implanted intraperitoneally into athymic mouse hosts and cultured in vivo for 20 days. A connective tissue consisting of bone, cartilage and fibrous tissues is formed by the stromal fibroblastic cells of marrow within the chambers. Cell kinetics and tissue differentiation have been studied using histomorphometric and biochemical analyses. Haemopoietic cell numbers decrease to less than 0.05% of the initial inoculum during the 20-day period. At 3 days an average of 15 stromal fibroblastic cells only are identifiable within the chambers. After 3 days there is a high rate of stromal cell proliferation with a doubling time of 14.5 h during the period from 3 to 8 days and an increase in the total stromal cell population by more than six orders of magnitude from 3 to 20 days. Thirteen to fourteen population doublings occur before expression of the first observable differentiation parameter, alkaline phosphatase activity. The data demonstrate that the mixture of connective tissues formed within the chamber is generated by a small number of cells with high capacity for proliferation and differentiation. This is consistent with the current hypothesis that stromal stem cells are present in bone marrow.

Alkaline Phosphatase↗
PubMed1977

Reasons for health office visits in an urban school district.

A survey of 3,048 school clinic visits (a 5% random sample by school of all visits during one school year) revealed the most frequent complaints or reasons for visits of school children in grades kindergarten through twelve. Minor trauma was the complaint identified in the largest proportion of clinic visits at all levels. Taking prescribed medication was the second most frequent reason for clinic visits at the elementary level. Headache was a frequent complaint presented in high school clinic visits.

Age Factors↗