No abstract

The quantitative method of measuring fibroblart precursors in populations of hcmatopoietic cella dcmonstrates that their concentration in blood doea not depend on the number of heart puncturw during blood collection. This meana that fibroblaat colonies, originating in monolayer culturw of blood cella, develop from circulating blood ah. From the indices of aH-thymidine labeling it is calculated that the mean generation time for fibroblasts in seven and llday cultures is 34 to 43 hours and that the proliferative pool in fibroblast colonier ia not less than 84 and 79 per cent respectively. The concentration of fibroblast precursors among nucleated cells of peripheral blood of guinea pigs ranges between 0.2 and 2 x 1 4 6 .

No abstract

Levels of cAMP were decreased and cGMP increased in progressive systemic sclerosis (PSS) fibroblasts compared with normal fibroblasts. PSS cells took up unusually large quantities of Ca++. The epinephrine‐induced increases in cAMP were diminished sixfold and epinephrine‐induced Ca++ uptake was abnormal in PSS cells. Considerable heterogeneity was observed in rheumatoid arthritis fibroblasts. Membrane‐bound abnormalities in (PSS) cells may be of importance in the defective control of collagen production in progressive systemic sclerosis.

No abstract