Biomedical subjects
R Kirsner
Publications and source records attributed to R Kirsner.
The effects of endothelin-1 on human dermal fibroblast growth and synthetic activity.
Endothelin-1 (ET-1) is the most potent vasoconstricting substance known, and is believed to have a fundamental role in the regulation of blood flow. It is a peptide produced and secreted by endothelial cells in response to hypoxia and injury, as well as by macrophages. These properties suggest that ET-1 may play a role during tissue repair. In this study, we have examined the effects of ET-1 on the growth and synthetic activity of human dermal fibroblasts. ET-1 stimulated DNA synthesis in serum-deprived cultures: this effect reached a mean value of 64% more than control (P < 0.01) at 2.5 ng/ml (10(-9) M) of ET-1. In contrast, the addition of ET-1 to fibroblasts at different densities and in 0, 3, or 10% fetal bovine serum (FBS) failed to increase cell counts. In 1% FBS, a 41% mean increase in cell counts compared to control values was observed in cultures treated with 2.5 ng/ml of ET-1 (P < 0.01). Incubation of dermal fibroblast cultures at 37 degrees C for 1 hr with increasing concentrations of 125I-ET-1 resulted in saturable binding and a half-maximal specific binding of 27.5 pM. Scatchard plot analysis of the binding showed a Kd of 224 pM and 11,400 high-affinity binding sites per cell. ET-1 had no effect on [14C]-glucosamine incorporation by fibroblasts and caused no increase in collagen synthesis, as measured by collagenase-sensitive [3H]proline incorporation and by salt precipitation of 3H-labeled collagen at acid and neutral pH successively.(ABSTRACT TRUNCATED AT 250 WORDS)
Pericapillary fibrin cuffs in venous ulceration. Persistence with treatment and during ulcer healing.
A recent hypothesis suggests that venous hypertension leads to ulceration through the formation of pericapillary fibrin cuffs, which are presumed to impede the exchange of oxygen and other nutrients. In this report, we evaluated by direct immunofluorescence the presence of pericapillary fibrin at the edge of venous ulcers during the course of treatment with elastic compression. In an initial group of 23 patients studied at baseline, pericapillary fibrin cuffs were detected in 20 (91%) of 22 patients. The intensity of fibrin staining, rated blindly on a scale of 0 to 3, could not be correlated with several baseline parameters, including the clinical presence and extent of lipodermatosclerosis, ulcer size, venous recovery time, and transcutaneous oxygen measurements (TcPO2) taken next to the ulcer. Eleven of this initial group of 23 patients were randomly selected to receive elastic compression treatment, and were evaluated for the persistence of pericapillary fibrin at 60 and 120 days. Although a reduction (mean +/- SD = 50.2% +/- 25.7) in ulcer size occurred in 10 of the 11 patients, pericapillary fibrin was still present at the ulcer edge and with undiminished intensity. We conclude that pericapillary fibrin cuffs in venous ulcers persist with compression treatment and in spite of healing, and are unlikely to be directly related to the development of ulceration.
Electrical stimulation and wound healing.
Living tissues possess direct current surface electropotentials that regulate, at least in part, the healing process. Following tissue damage, a current of injury is generated that is thought to trigger biological repair. In addition, exogenous electrical stimuli have been shown to enhance the healing of wounds in both human subjects and animal models. Intractable ulcers have demonstrated accelerated healing and skin wounds have resurfaced faster and with better tensile properties following exposure to electrical currents. This article examines the bioelectric properties of living systems and reviews the existing literature on electrical stimulation and wound healing.