RESUMEN
Asymmetrical pulsing low voltage current was supplied via electrodes to cultured rat fracture callus cells and human peripheral blood lymphocytes. The [3H]thymidine incorporation of the callus cells and 5-[125I]iodo-2'-deoxyuridine incorporation of the lymphocytes were determined. The growth pattern of callus cells (estimated by cellular density) did not respond to electrical stimulation. However, the uptake of [3H]thymidine was increased at the early phase of cell proliferation and inhibited at later phases of proliferation. The [3H]thymidine uptake of confluent callus cell cultures did not respond to electrical stimulation. Lymphocytes reacted in a similar way; stimulated cells took up more DNA precursor than control cells at the early phase of stimulation. During cell division, induced by the mitogens phytohemagglutinin and Concanavalin-A, the uptake of DNA precursor by stimulated cells was constantly inhibited. The results suggest that electrical stimuli affect the uptake mechanisms of cell membranes. The duality of the effect seems to be dependent on the cell cycle.
Asunto(s)
Callo Óseo/citología , Linfocitos/citología , Animales , Callo Óseo/efectos de los fármacos , División Celular , Células Cultivadas , Concanavalina A/farmacología , Estimulación Eléctrica , Humanos , Idoxuridina/metabolismo , Radioisótopos de Yodo , Linfocitos/efectos de los fármacos , Fitohemaglutininas/farmacología , Ratas , Ratas Endogámicas , Estimulación Química , Timidina/metabolismo , TritioRESUMEN
The effect of rigid plate fixation on the chemical composition of cancellous interposition grafts was studied in rabbit-fibular bones. The concentrations of hexosamines and, to a lesser degree, of hydroxyproline and nitrogen, were high in the graft for the first 6 weeks, decreased from weeks 6 to 12, but remained higher than the corresponding values for the controls throughout the experiment (52 weeks). The ratio of hexosamines to hydroxyproline was highest for the graft at 3 weeks, indicating formation of cartilage and osteoid. The initially low calcium concentration of the graft increased by 35 per cent from weeks 1 to 6, decreased from weeks 6 to 12, and remained below normal thereafter in comparison with corresponding values for the cortical host bone. The ratio of calcium to hydroxyproline increased throughout the experiment, reflecting maturation of the graft to lamellar bone. Thus, biochemically the early incorporation of rigidly fixed cancellous interposition grafts resembles the healing of unimmobilized fractures by callus formation.
Asunto(s)
Placas Óseas/efectos adversos , Huesos/metabolismo , Fracturas Óseas/metabolismo , Animales , Trasplante Óseo , Calcio/metabolismo , Fijación de Fractura/métodos , Hexosaminas/metabolismo , Hidroxiprolina/metabolismo , Nitrógeno/metabolismo , Fósforo/metabolismo , Conejos , Cicatrización de HeridasRESUMEN
The effect of rigid plate fixation on the chemical composition of cortical interposition grafts were studied in rabbit tibio-fibular bones. The concentration of hexosamines increased both in the graft and in the host bone during the first 6 weeks, but thereafter decreased. The concentrations of hydroxyproline and nitrogen increased throughout the experiment. The ratio of hexosamines to hydroxyproline increased in the graft for the first 6 weeks, indicating formation of immature osteoid and bone during this period, but thereafter decreased. The calcium concentration of the graft decreased significantly during the first 12 weeks and remained below normal (-10 to -19 per cent). The mineralization of the graft, assessed by the ratio of calcium to hydroxyproline, decreased continually. The results suggest that cortical bone grafts stabilized with rigid plates heal with only slight chemical signs of callus formation. The demineralization of the graft reflects the porotic changes that take place under the plate.