Vascularized collagen-glycosaminoglycan matrix provides a dermal substrate and improves take of cultured epithelial autografts.

Cultured epithelial autografts are an important adjunct in treating severely burned patients, greatly expanding the epidermis using a small donor site. Problems with cultured epithelial autografts include the time delay to culture cells to confluence and variable take on full-thickness wounds. Dermal allografts have been used as a substrate to improve the take of cultured epithelial autografts. This study examined the effect of a vascularized collagen-glycosaminoglycan matrix as a substrate for cultured epithelial autografts. The matrix was grafted onto 12 full-thickness wounds in Yorkshire pigs and allowed to vascularize for 10 days. The cultured epithelial autografts were applied over the vascularized collagen-glycosaminoglycan matrix (n = 12) or onto freshly excised full-thickness wounds (n = 10). Gross and histologic observations were made over a 3-week period. Gross observations at 7 days indicated cultured epithelial autografts to have nearly complete confluence when applied to wounds treated by collagen-glycosaminoglycan, whereas cultured epithelial autografts applied to freshly excised wounds did not take. Gross determination of epithelial confluence was verified by histologic analysis of randomly selected wounds. Histologic epithelial confluence of cultured epithelial autografts on collagen-glycosaminoglycan (98 +/- 4 percent) was significantly greater than that on full-thickness wounds (4 +/- 10 percent). Electron microscopy of the cultured epithelial autografts/collagen-glycosaminoglycan construct demonstrated anchoring fibrils at the dermal-epidermal junction at day 7. The neoepidermis of wounds treated by cultured epithelial autografts/collagen-glycosaminoglycan was hyperplastic at day 7 but developed a normal maturation sequence by 21 days. Results from this study suggest that vascularized collagen-glycosaminoglycan matrices produce a favorable substrate for cultured epithelial autografts and may improve cultured epithelial autografts take in burn patients.

A finite-element model predicts thermal damage in cutaneous contact burns.

Thermal injury results from exposure of skin elements to an externally applied heat source. Finite-element analysis of heat transfer in cutaneous burns allows for an accurate prediction of tissue time-temperature relationships throughout the exposed tissue. A two-dimensional, axisymmetric, finite-element model of a contact burn was constructed, and damage integrals were calculated by applying the Arrhenius equation to the time-temperature profiles at each point. The epidermis, dermis, and subcutaneous fat were modeled as uniform elements with distinct thermal properties. Heated aluminum blocks were applied to Yorkshire pigs for 10 to 80 seconds to produce contact burns. Wound biopsies taken at 1, 24, and 48 hours were examined histologically and measured for the depth of burn. A significant deepening of the gelatinized tissue was observed in tissue taken from 1 hour to 24 hours. The finite-element prediction of cutaneous contact burn damage correlated well with histologic observations in this porcine model.

Effect of third-party reimbursement on use of services and indexes of management among indigent diabetic patients.

OBJECTIVE: To determine the effect of third-party reimbursement on the use of services and indexes of diabetes-related health management among inner-city diabetic patients. RESEARCH DESIGN AND METHODS: Adult diabetic patients (n = 158; 67% women, 33% men) from an inner-city diabetes clinic were categorized by level of third-party medical coverage: complete reimbursement for all services (full); partial reimbursement (part); and no reimbursement (none). Patients were followed for 13 mo. Use of billable medical services, diabetes clinic visits, emergency room visits, and hospital admissions were recorded. Use of a free, day-time diabetes telephone hot line was also documented. Indexes of diabetes-related health management, HbA1, blood pressure, and weight were compared from the beginning and the end of the study. Diabetes complications were scored and tabulated. RESULTS: Univariate analysis showed that patients with full reimbursement were more likely to use services than patients without reimbursement. When the combined effects of reimbursement status, age, sex, type of diabetes, and diabetes complications on use of services were analyzed together in a multivariate analysis, complications was the best predictor of admissions to the hospital and whether a patient called the hot line. IDDM patients and patients with full reimbursement were most likely to have an emergency room visit. Age was the best predictor of diabetes clinic attendance. No difference was noted in blood pressure or weight among the reimbursement groups at the beginning and end of study. However, the trend was toward (P < 0.05) an increase in HbA1 in the none group. CONCLUSIONS: Among inner-city diabetic patients, multiple factors influence use of medical services. Indigent diabetic patients without third-party reimbursement were observed to have a rise in HbA1. These factors should be taken into consideration when planning strategies to prevent diabetes complications and the most effective allocation of health-care resources.