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Biomedical subjects

D Ratcliff

Publications and source records attributed to D Ratcliff.

6 recordsLinked to original sources
PubMed1993

Fibroblast behavior in the embryonic chick heart.

Intracardiac fibroblasts (mesenchymal cells) of Hamburger and Hamilton stage 36 chick heart reside in the epicardium and atrioventricular valves. The characteristics of the epicardial fibroblasts include segregation from the myocytes of the heart wall myocardium, voluminous extracellular matrix production, and some cell proliferation activity. The atrioventricular fibroblasts intermingle with myocytes at the mutual border between these tissues, produce smaller amounts of extracellular matrix, and show very active cell proliferation. Is the behavior of each population of fibroblasts predetermined or is each responding in a reversible fashion to local environment? A cell aggregate culture system, which permits 3-dimensional cell-cell and cell-matrix interactions, is used to study the behavior of each isolated population of fibroblasts in vitro. In the presence of serum-free medium, each population produces very little extracellular matrix, has relatively low mitotic activity, and does not segregate from myocytes when the aggregate is composed of randomly intermixed myocytes and fibroblasts. In the presence of chicken serum, each population increases matrix production, increases cell proliferation, and sorts from myocytes. Thus, we suggest that the two populations of fibroblasts in the developing heart are responding to local environments and the differences observed in vivo are not the consequence of irreversible states of cellular differentiation.

Animals↗
PubMed1992

Statement: occupational therapy services in work practice.

Occupational therapy practitioners focus on the individual's ability to participate in productive occupations throughout their life span. Through prevention, assessment, and intervention strategies, occupational therapy practitioners often collaborate with other members of the health care team and assist persons to optimize their ability to engage in purposeful occupation while facilitating a safe and successful entry into or return to work.

Accidents, Occupational↗
PubMed1979

Phosphorus content of bovine rib: influence of earlier biopsy of the same rib.

Serial sampling of bovine rib is undertaken experimentally to monitor changes in the degree of skeletal mineralisation. The validity of this approach depends on the assumption that the previous sampling of a bone does not influence the composition of a sample obtained subsequently. To test this, the effect of a prior biopsy sampling on phosphorus content of the remaining bone was determined at various times after the initial sampling. A preliminary biopsy sample was taken with a 1.5 cm diameter trephine from the left 12th rib of 40 cattle; experimental samples were taken from the same rib of 10 of the cattle at three, six, nine and 12 months later, for comparison with similar samples taken concurrently from the right 12th rib. The phosphorus content of the second left rib was significantly lower than that of the right (control) rib at the three-month interval, particularly where the sampling site was ventral, rather than dorsal, to the site from which the initial biopsy was obtained. No effects of previous biopsy sampling were observed after six, nine or 12 months.

Animals↗