Growth factor expression with different wound treatments after laser resurfacing.

BACKGROUND: Many studies have demonstrated that the specific method of wound dressing used may affect the healing process. However, the effect of the method of wound dressings on the expression of growth factors is not well documented. OBJECTIVE: The aim of this study was to evaluate the effects of different methods of treatment on the healing process and the expression of growth factors (epidermal growth factor, basic fibroblast growth factor, transforming growth factor-beta(2) [TGF-beta(2)], platelet-derived growth factor-A, and platelet-derived growth factor-B) by histologic study, immunohistochemistry, and reverse transcription-polymerase chain reaction. METHODS: In this study, we produced wounds with a CO(2) laser on the backs of rats and used 4 different methods of wound treatment: occlusive dressing material, petrolatum ointment, beta-sitosterol ointment, and exposure to air (untreated) as a control. Five-millimeter biopsy specimens were obtained 1, 3, 5, 7, and 10 days after surgery for histologic evaluation and expression of growth factors from four different dressing sites. RESULTS: By microscopic examination, there was an acceleration of wound healing in the occlusive dressing wounds, as well as a lesser improvement in healing times with the petrolatum and beta-sitosterol-treated wounds, compared with the air-exposed control subjects. With immunohistochemistry, we observed that the tissue expression of TGF-beta(2) remained at a clearly lower level during the entire duration of wound healing in the occlusive dressing wound compared with the other treatment wounds. With reverse transcriptase-polymerase chain reaction, however, our data did not reveal statistically significant differences among the messenger RNA levels. CONCLUSIONS: Our results suggest that a decrease in the expression level of TGF-beta(2) under occlusive dressings could provide an environment in which the growth of human epidermal keratinocytes and re-epithelialization is promoted.

A Cochlear Implant System with Infra-red Telemetry for Behaving Animals.

A new cochlear implant system for animal experiments is proposed. The system uses a DSP-based sound processor to implement the six-channel continuous interleaved sampling (CIS) speech processing strategy. An infra-red telemetry is designed to remotely connect the power-demanding sound processor to receiver/stimulator attached on the animal. This enables the animal to move freely. The receiver/stimulator consumes about 40mW, thus can operates for about 200hours without changing battery.