Biomedical subjects
Publications and source records attributed to C Merrill.
We have developed a living skin equivalent, which serves as a skin substitute in experimental animals. On application it is rapidly vascularized, it inhibits wound contraction, and it is immunologically tolerated and persists for as long as it is allowed to remain in place. It comes to resemble normal skin, although it lacks secondary derivatives, the cells for which may in time be available for incorporation into the fabricated tissue.
A weight control program for junior high school students was developed to change eating, exercise and habit patterns. The course included dietary management, physical activity and behavior modification techniques. Classes were structured to emphasize peer group involvement and daily practical application. The curriculum was compiled in a book for educational personnel. The program was tested as a pilot project with a selected group of eighth grade obese adolescent girls and a comparison group. Immediately after the course, the subjects' percent of overweight had decreased; at a subsequent eight-month follow-up, additional losses were noted. The percent of overweight of the girls in the comparison group remained relatively unchanged. While the program was successful with this particular group of students, several key questions, requiring further study, were defined.
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Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the concentration of an inhibitor such as Colcemid. Fibroblasts of high population doubling level propagated in vitro, which have left the cell cycle, can carry out the contraction at least as efficiently as cycling cells. The potential uses of the system as an immunologically tolerated "tissue" for wound healing and as a model for studying fibroblast function are discussed.
We have developed an interactive computer system for analysing cell lineage data. It can be utilized in studies of cell motility, cell division, cell differentiation, and cell aging. It has enabled us to document the heterogeneity of human foreskin fibroblasts in culture and to propose that loss of proliferative potential may mean that cells enter a state of differentiation which makes them unable to respond to mitotic stimulation. Our method, which enables us to apply immunological and cytochemical probes after recording the history of a cell lineage, should allow us to define precisely features which uniquely distinguish cycling from noncycling cells on an individual cell basis.
We have examined the hypothesis that diploid cells grown in vitro age, and propose that only proliferative potential and not life-span is telescoped. We suggest that explanted or transplanted diploid cells are driven to divide by the process of subculturing in vitro or in vivo and, in response to this pressure, also complete their differentiation and become refractory to further mitotic stimulation. We conclude that differentiation rather than "mortality" distinguishes diploid from transformed cells and that the former may not age in vitro, but are lost because culture methods are selective for cycling cells.
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4CMB, 4HMB and BC were assayed for mutagenic activity using the 'microtitre' bacterial fluctuation test without metabolic activation. 4CMB was positive in strains of Salmonella typhimurium detecting both base-substitution and frameshift mutation. BC was weakly positive only in the strain which detects base-substitution mutation. 4HMB was negative in both strains. 4CMB and 4HMB were equally toxic to the strains, whilst BC was comparatively less toxic.
Arteriovenous fistulas of the internal mammary artery are rare. This second recorded instance of congestive heart failure from such a fistula occurred in an aged patient 19 years after a gunshot wound. The etiologic and pathophysiologic classifications of 19 cases already reported in the world literature are discussed, as are symptoms, diagnostic methods, and observations during management of this type of fistula.