Biomedical subjects
Publications and source records attributed to J H Haynes.
Erysipelas is a superficial cellulitis that affects the skin and subcutaneous tissues. There is also prominent lymphatic involvement. Group A streptococci are the usual cause of this painful infection, but the responsible organisms cannot always be cultured from the fiery red, edematous, sometimes vesicular rash. A fulminating case developed in the left leg of a man whose veins had been harvested four months earlier for coronary artery bypass surgery.
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In many species, open cutaneous fetal wounds do not heal in utero. Such open wounds have been shown to close only after their exclusion from amniotic fluid, thus leading to the hypothesis that amniotic fluid inhibits open wound healing. Therefore the effect of amniotic fluid exposure on the healing of open fetal skin wounds was studied. Fetuses of New Zealand White rabbits received a full-thickness circular 4 mm diameter skin punch biopsy wound. Wounds were left uncovered, covered with a latex patch, or covered with a latex patch with a central hole (doughnut). This third group provided for wound exposure to amniotic fluid while controlling for any wound splinting effect of the patch. Wounds were harvested after 5 days, the wound area was determined planimetrically, and wound edges were examined by means of light microscopy. Analysis of glycosaminoglycans in the wound extra-cellular matrix was performed on a separate group of wounds treated similarly. Uncovered wounds enlarged by an average of 60%, whereas wounds covered with the doughnut patch enlarged by an average of 24%. In contrast, the wounds in the patch-covered group decreased in size by an average of 84%. Histologically all groups contained proliferating fibroblasts and epithelial migration at the wound edge but also an absence of granulation tissue. The patch-covered wounds, which had decreased wound area, were significantly enriched in hyaluronic acid. These results suggest that the healing of the patch-covered wounds occurs without the formation of granulation tissue, presumably through a process of cellular migration and proliferation and that healing was inhibited by exposure to amniotic fluid. Hyaluronic acid has been shown to be permissive of cellular migration and to play a key role in tissue regeneration. Therefore, we speculate that direct exposure of open wounds to amniotic fluid during the late stages of fetal development in the rabbit prevents hyaluronic acid deposition, which in turn may alter wound closure.
Fetal wound healing proceeds rapidly with minimal inflammation and fibroplasia and little or no scar formation. These observations have led to the hypothesis that fetal wound healing more closely resembles regeneration rather than adult wound repair. To test this hypothesis, this study used ultrastructural analysis of fetal and adult fibroblasts and collagen to gain greater insight into differences in the healing processes. Full-thickness, primarily closed linear incisions were created dorsally on 24-day gestational age fetal rabbits (n = 9). The fetuses were killed 5 days later, and the wounds were excised and evaluated with transmission electron microscopy. Similarly, uninjured fetal skin of the same gestational age was obtained and analyzed. Adult rabbit dermal wounds were analyzed after 8 days of healing. Resting adult dermal fibroblasts had features of quiescent, inactive cells, whereas adult wound fibroblasts were highly active and filled with secretory vesicles. In contrast, both fetal normal dermal and wound fibroblasts appeared highly active and contained numerous secretory vesicles. In the adult wound, collagen fibril diameter was only 45% of the diameter of normal dermal collagen. However, fetal wound collagen fibrils were basically the same as normal dermal collagen, having a diameter that was 82% of the size of dermal collagen. These observations suggest that fetal wound fibroblasts do not require activation from an inactivated state and that fetal wound collagen deposition undergoes more rapid organization and maturation. These findings have significance in extending our understanding of the rapidity and functional superiority of fetal wound healing compared with adult wound healing.