Xanthine oxidase contributes to lung leak in rats subjected to skin burn

Therapeutic effects of xanthine oxidase inhibitors: renaissance half a century after the discovery of allopurinol

The prototypical xanthine oxidase (XO) inhibitor allopurinol, has been the cornerstone of the clinical management of gout and conditions associated with hyperuricemia for several decades. More recent data indicate that XO also plays an important role in various forms of ischemic and other types of tissue and vascular injuries, inflammatory diseases, and chronic heart failure. Allopurinol and its active metabolite oxypurinol showed considerable promise in the treatment of these conditions both in experimental animals and in small-scale human clinical trials. Although some of the beneficial effects of these compounds may be unrelated to the inhibition of the XO, the encouraging findings rekindled significant interest in the development of additional, novel series of XO inhibitors for various therapeutic indications. Here we present a critical overview of the effects of XO inhibitors in various pathophysiological conditions and also review the various emerging therapeutic strategies offered by this approach.

Caffeic Acid Phenethyl Ester Improves Oxidative Erythrocyte Damage in a Rat Model of Thermal Injury

Oxygen-derived free radicals impair cell membrane functions and induce circulatory disturbances, and free radicals, such as superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite, have been suggested to play important roles in the pathogenesis of major burn injuries. The present study investigated the effects of thermal injury on erythrocyte lipid peroxidation and antioxidant status and investigated the effects of caffeic acid phenethyl ester (CAPE), a new antioxidant and anti-inflammatory agent, in rats subjected to thermal injury. Burn injury caused a remarkable increase in erythrocyte lipid peroxidation, levels of nitric oxide (NO), and activities of antioxidant enzymes and xanthine oxidase (XO). The treatment with CAPE decreased both activity of burn-induced XO activity and levels of NO in the erythrocytes. In conclusion, CAPE treatment resulted in decreased erythrocyte lipid peroxidation in thermal injury and helped to prevent oxidative damage by decreasing activity of XO and levels of NO.

A primary burn wound does not slow the contraction rate of an adjacent excisional wound

The response to major burn injury includes systemic release of mediators that may have an effect on wound healing. The authors evaluated the effect of a burn injury on the contraction of an excisional wound adjacent to the burn, and the effect of plasma derived from burn-injured animals on the contraction of the fibroblast-populated collagen matrix (FPCM). Nine rats (90-100 days old) under anesthesia received a standardized 40% total body surface area burn to the dorsum, and eight rats (controls) were sham burned. Immediately thereafter all animals had a square (2.25 cm2) of unburned dermis excised from the dorsum, superior to the burn wound. The excisional wound area was measured at 2 to 3-day intervals postoperatively. Plasma was collected from some animals on postburn day 15; the contraction-stimulating ability of burn vs. control plasma was measured in the FPCM. All animals remained free of sepsis. The excisional wound area in all animals decreased to 50% and then 25% of the initial area after approximately 4 and 8 days respectively. The rate of wound contraction (i.e., wound area reduction) did not differ between burn and control animals. Contraction stimulated by 5% plasma in the FPCM (expressed as a percentage of the original matrix area) was 70.2+/-6.4 (standard deviation) mm2 vs. 62.4 +/-3.9 mm2 for burn vs. control rats respectively (p>0.05). Burn injury in this model did not alter the contraction of an excisional wound at an unburned site. There was no significant difference in the contraction-stimulating ability (FPCM model) of plasma from the burned rats compared with plasma from unburned control rats. Burn injury appears to have an inconsequential effect on the contraction of an adjacent wound.

Mucosal protection from intestinal ischemia-reperfusion reduces oxidant injury to the lung

The authors investigated whether amelioration of intestinal mucosal injury, due to ischemia-reperfusion (I/R), with oxygenated perfluorocarbon (PFC) would reduce an oxidant-generated lung injury. The small intestine is increasingly recognized as a primary effector of distant organ injury. Clinical and experimental studies suggest oxidant species and activated neutrophils as the agents responsible for lung injury after intestinal I/R. The role of intestinal mucosal injury has not been defined. Oxygenated PFC was perfused through the lumen of the intestine during periods of I/R. Portal venous effluent was examined for reactive oxygen species and lung tissue was examined for lipid peroxidation. Luminal perfusion of oxygenated PFC during intestinal I/R reduced oxidant species in the portal blood. This correlated with a reduction in lung lipid peroxidation. Oxygenated PFC prevented intestinal mucosal injury resulting from induced I/R. Amelioration of mucosal injury reduced oxidant generation in the portal venous circulation that was proportional to the reduction in measured lung injury. Protection of the mucosa with intraluminal oxygen may prevent I/R-associated lung injury.