Clinical and Molecular Perspectives of Deep Tissue Injury: Changes in Molecular Markers in a Rat Model

Undermining incision and healing of deep pressure ulcers: a prospective cohort study of pressure ulcers by the Japanese national hospital organization

Undermining is one of the most challenging complications of deep pressure ulcers. Recommendations in most guidelines are based only on expert opinions. Here, we examined the relationship between surgical incision of the undermined space and pressure ulcer healing through a Japanese multicenter prospective cohort study. A total of 162 patients with undermining in 40 national hospitals in Japan were enrolled from July 2007 to June 2009. The incision group included 39 patients (24.1%) whose undermining was surgically incised during the observational period. Their 4-week follow-up data on pressure ulcer severity and areas of healthy granulation tissue were recorded as outcome variables using the DESIGN-R pressure ulcer assessment tool. The 4-week follow-up was restarted after the incision in the incision group. The outcome variables over time were compared between the two groups using a linear mixed model with or without adjustment for demographic and other variables. The incision group showed more rapid improvement in the total and granulation DESIGN-R scores compared with the nonincision group (p < 0.001 and p = 0.007, respectively, in the crude models). This study may provide the first considerable evidence to support that surgical incision of undermining may promote healing of deep pressure ulcers.

Aging-like skin changes induced by ultraviolet irradiation in an animal model of metabolic syndrome

Both physiological skin aging and pathologic photo-aging caused by ultraviolet (UV) irradiation are mediated by latent inflammation and oxidative stress. Although numerous animal skin-aging models have used UV irradiation, most require massive doses or long-term irradiation. To establish a more refined skin-aging model, we focused on an animal model of metabolic syndrome (MS) because MS involves damage to various organs via oxidative stress or inflammation, similar to the changes associated with aging. We hypothesized that MS skin might exhibit more aging-like changes after milder, shorter-term UV irradiation than would normal animal skin under similar conditions, thus providing a useful model for skin aging. The authors therefore examined the skin from Tsumura Suzuki obese diabetic (TSOD) mice (MS model) and control Tsumura Suzuki non-obese (TSNO) mice before and after UV irradiation. Skin from TSOD mice had a thinner epidermis and dermis, a thicker fatty layer, reduced density and convolution of the fragmented collagen fibers, and upregulated expression of tumor necrosis factor (TNF)-α, a dual marker for inflammation and aging, compared to the skin from TSNO mice. UV irradiation affected TSOD skin more severely than TSNO skin, resulting in various changes resembling those in aged human skin, including damage to the dermis and subcutaneous fatty tissue, infiltration of inflammatory cells, and further upregulation of TNF-α expression. These results suggest that UV-irradiated TSOD mice may provide a new model of skin aging and imply that skin from humans with MS is more susceptible to UV- or aging-related damage than normal human skin.