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INTRODUCTION: The care and healing of skin defects resulting from different causes has been the object of research to achieve rapid and complete skin regeneration. Hydrogels have been used for their ability to maintain hydration during wound healing, absorb wound exudate, and cover the underlying tissue without adherence while being transparent. In this study, we evaluated the efficacy of a hydrogel (H) with encapsulated porphyrin (H+P) on a rat model of surgically-induced skin defects. METHODS: Four round 6 mm diameter skin defects were performed under general anesthesia on the dorsal area of 24 three-month-old "Young" and 24 twelve-month-old "Mature" male rats. Each age group was separated into the Control, H, and H+P groups, n=8 each, where no therapy, H, or H+P was respectively applied daily for 20 days. Digital photographs and skin biopsies were taken on the third, seventh, 10th, and 20th postoperative days and evaluated by planimetry, histology, and immunohistochemistry. RESULTS: Planimetry results demonstrated significantly decreased perimeter, diameter, and area measurements (p<0.005) of group H+P compared to Control and H groups on days 10 and 20 in the young rats, while in the mature rats, the significant differences were evident earlier (perimeter third day p<0.05; diameter and area seventh day p<0.05 and p<0.005, respectively vs. H). Granulation and scar tissue formation were also reduced in the H+P groups although they were not statistically significant. CONCLUSIONS: The application of H+P on the skin defects benefited the healing process in both young and mature animal groups, as evidenced by the statistically significant findings of planimetry. The beneficial healing process was more pronounced in the mature animals, both in the level of statistical significance as well as regarding time (evident already on the third day of healing), probably due to porphyrin assisting the reduced healing rate, which is observed in organisms of advanced age.
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BACKGROUND: Erythema can be described only through subjective evaluation, except when it is quantified by digital image analysis software. Using such software, the authors performed comparisons of the erythema produced after skin closure of clean surgical wounds. Five suture materials were compared with respect to the local skin irritation that was caused. Different quantities of erythema are produced by suture material after the skin closure of clean surgical wounds. The authors present an objective method of measuring how unreactive a suture material is in comparison with another when applied to the skin. METHODS: The suture materials polydioxanone, polypropylene blue, polyamide 6, metallic clips, and polyglactin were compared in the present study. Digital photographs of 100 patients were compared by means of software, evaluating red color superiority (mean value of red color) in the region surrounding the wound. RESULTS: The least to most irritation caused to the skin by different suture materials was established for paired data. The Kolmogorov-Smirnov criterion and the Wilcoxon signed rank test were used. Polydioxanone was found to have the best performance, followed in order by polyglactin, polyamide, polypropylene, and metallic clips. Immediately after suture removal, differences between the effects of suture materials were statistically significant on postoperative day 10. CONCLUSIONS: Absorbable sutures can be used in skin closure of clean surgical wounds and can produce less erythematous reaction than nonabsorbable ones. Digital image analysis is a reliable method of quantitative evaluation of skin erythema resulting after skin closure of surgical wounds.