Basic research of factors affecting the formation of granulation tissue in wound healing.

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1. Intraperitoneal and oral administration of Piracetam accelerated wound healing in rats. In both incisional wounds and open wounds, piracetam raised wound breaking strength.2. S- 1452 ; thromboxane A2 blockade, did not show any beneficial effects of rat wound healing. The failure of this study would be attributed to the antiplatelet actions.3. We examined a simple experimental model in the rat and investigated the mechanism of formation of pressure ulcers. We planned three patterns of ischemia-reperfusion procedure. In each pattern the pressure of the treated site and total time of ischemia was same. Monitoring the skin blood flow, reactive hyperemia was not seen in one pattern. One week after experiment, in two patterns, skin necrosis of the treated sites were recognized. By this experiment, it is suggested that the formation of pressure ulcers is not dependent upon only the total pressure but also the patterns of pressure.4. We estimated the efficacy of keloid implantation to nude mouse and creating hypertrophic scar in the rabbit ears. The implanted keloid disappeared rapidly. The rabbit ear wound were got hypertrophic with cauterized the wound margin. So the delay of epithelization has the key role for keloid formation.5. The expression of markers of epidermal proliferation and differentiation was assessed immunohistologically in hypertrophic scar tissue and site-matched controls from the same patients. The epidermis appeared thicker in all-hypertrophic scars when comparing with controls. Staining for Ki-67 antigen revealed an increase in hypertrophic scar basal cells in twelve cases out of fourteen cases. No difference in the expression of differentiation markers was observed between hypertrophic scars and controls.Our results raise the" possibility that acanthosis in hypertrophic scar represents a feature, which is shared with tissue expansion and, a number of conditions with the epidermis covering proliferative dermal tumors.