Both dermal matrix and epidermis contribute to an inhibition of wound contraction

Contracture is a major detriment to functional recovery from large wounds. To determine the relative value of dermal replacement and epidermal coverage in inhibiting wound contraction, five full-thickness wounds (all 5 x 5 cm2) were placed on the back of 8 swine and treated in the following manner: (1) open wound, (2) porcine acellular dermis (analogous to AlloDerm for human use), (3) porcine acellular dermis with epidermal autograft placed 7 days postwounding, (4) porcine acellular dermis with immediate epidermal autograft, and (5) conventional-thickness autograft. Scar dimensions and punch biopsies were taken at days 14 and 30 postwounding. The planimetry results demonstrated that wound contraction was significantly greater with the open wounds (group 1) than all other wounds with a dermal substitute. Furthermore, wounds with initial epidermal coverage had significantly less contraction than unepithelialized wounds (14.8 +/- 1.1 cm2 at day 14 in wound group 2 vs. 20.4 +/- 0.6 cm2 in wound group 4; p < 0.05). Biopsy results revealed that wounds with initial epithelial coverage had the least amount of inflammation. These findings suggest that both dermal matrix and epidermal coverage contribute to an inhibition of wound contraction and that prompt epithelial coverage appears to impede contraction by reducing inflammation.

Enhancing high-speed digitization of single-unit neuronal activity on a microcomputer using a hybrid software-hardware technique

A new data acquisition technique allows a microcomputer simultaneously to digitize spikes at high rates, analyze spike waveforms for computer-based spike separation and manage other control tasks. The technique has two key features: a software scheduling routine written in a high-level language and a hardware analog delay of neuronal signals using simple hardware external to the computer. The technique provides an alternative for real-time data acquisition and can be used on microcomputers without requiring interrupt processing and assembly language programming.