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Proteolytic enzyme activity in the granulation tissue of the human burn wound.

A procedure for adsorbing enzymes from the human burn wound onto solid sheets of substrate is described. Using this technique, low levels of enzyme activity with chymotrypsin-like specificity can be demonstrated in the wound approximately 2 weeks after injury. This activity disappears at about 5 weeks after the burn. The enzyme activity corresponds with the clinical experience for the time course of natural loss of the burn eschar. A trypsin-like enzyme of very low level activity is present in the wound. No collagenase was detected in the human burn wound. Preliminary evidence shows an additional leucine-specific enzyme in the human burn wound. A more detailed analysis of enzymes in the human burn wound should permit the development of a useful artificial debriding agent. Presently these preparations must be used with caution.

Adolescent↗

Hyaluronic acid prevents oxygen free-radical damage to granulation tissue: a study in rats.

Oxygen free-radicals are known to impair wound healing after ischaemia-reperfusion or polymorphonuclear cell stimulation. Furthermore, they reduce the breaking strength of all recent wounds and might be a cause of wound leakage. This study was performed to evaluate whether or not hyaluronic acid can reduce the risk of wound impairment caused by free-radicals, in rats with abdominal sepsis, polymorphonuclear cell stimulation or cytochrome C function derangement produced by xenobiotics. Male Sprague-Dawley rats with open wounds received phenazine methosulfate or zimosan, or had abdominal sepsis to induce oxygen free-radical generation. There were three groups of treatment: hyaluronic acid cream, hyaluronic acid ethyl ester gel, and placebo. The reduction in wound size was measured from the 1st to the 11th postoperative day; biopsies were taken for histological evaluation. Every other day, a gentle debridement was performed in all the groups of animals. We found that hyaluronic acid and its ethyl ester derivative significantly improved the wound healing of rats subjected to an increased generation of oxygen free-radicals. It remains to be established whether or not hyaluronic acid acts as a scavenger of free-radicals.

Animals↗

Murine chemokine CXCL2/KC is a surrogate marker for angiogenic activity in the inflammatory granulation tissue.

OBJECTIVES: A wide range of compounds inhibit formation of new blood vessels in a variety of models, accompanied by decreases in pro-angiogenic cytokines. The authors sought a surrogate marker for the complex process of neovascularization by correlating inhibition of cytokine production with anti-angiogenic effect. METHODS: Three anti-angiogenic compounds, clotrimazole (120 mg kg(-1) day(-1)), thalidomide (100 mg kg(-1) day(-1)), and rosiglitazone (10 mg kg(-1) day(-1)), were used to inhibit angiogenesis developing over 9 days, in sponges implanted subcutaneously in Swiss mice. Angiogenesis was assessed by hemoglobin content and by histology. Content of cytokines in implants was measured by specific immunoassays and accumulation of neutrophils or macrophages in implants by measuring myeloperoxidase or N-acetylglucosaminidase activity, respectively. RESULTS: These compounds caused equal inhibition of angiogenesis (about 40%). However, implant levels of vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF-alpha) or the macrophage chemoattractant cytokine, CCL2/MCP-1/JE, and accumulation of macrophages were more variably inhibited. Only the neutrophil chemokine, CXCL2/KC, was inhibited equally by the three compounds, in this model. CONCLUSIONS: Anti-angiogenic effect was most clearly and closely correlated with levels of the chemokine KC. Thus, measurement of the chemokine KC might provide an adequate surrogate marker for the functional process of neovascularization in our model.

Angiogenesis Inhibitors↗

The evaluation of subatmospheric pressure and hyperbaric oxygen in ischemic full-thickness wound healing.

We evaluated the efficacy of subatmospheric pressure and hyperbaric oxygen (HBO) as adjuncts in the treatment of hypoxic full-thickness wounds in a rabbit model. We hypothesized that subatmospheric pressure and HBO independently are effective in improving wound healing in the ischemic wound model and that when they are used in combination there is an increased positive effect on wound healing. Using a standard ischemic wound model four full-thickness wounds were created on each ear of 41 male New Zealand white rabbits (N = 82 ears). On each rabbit one ear was dressed with the vacuum-assisted closure (VAC) device and connected to suction; the other was dressed identically without the suction and suction tubing. Twenty rabbits were treated with HBO daily for 10 days at 2.0 atmospheres absolute for 90 minutes plus descent and ascent times. Necropsy on all rabbits was performed on postoperative day 10. Four ischemic wound treatment groups were evaluated: Group 1 (N = 21) VAC dressing alone; Group 2 (N = 20) VAC dressing plus HBO; Group 3 (N = 21) VAC dressing to suction alone; and Group 4 (N = 20) VAC dressing to suction and HBO. Using light microscopy a veterinary pathologist blinded to treatment groups quantified peak granulation tissue, granulation tissue gap, and epithelialization tissue gap. Data were analyzed by analysis of variance with significance indicated by P < 0.05. Statistical significance was found in a comparison of VAC dressing to suction and VAC dressing alone for peak granulation tissue and granulation tissue gap both with and without use of HBO. VAC device use appears to increase the rate of healing in a rabbit ischemic wound model. HBO therapy did not significantly affect the rate of healing in this model.

Analysis of Variance↗

Lipid peroxidation dependent aldrin epoxidation in liver microsomes, hepatocytes and granulation tissue cells.

Lipid peroxidation activity was determined in liver microsomes, hepatocytes and cultured granuloma cells by measuring ethane and pentane production with an improved capillary gas chromatographic method. Lipid peroxidation initiated by ferrous ions and NADPH produced significantly more hydrocarbons at 4% O2 than under atmospheric (21% O2), hyperoxic or hypoxic conditions. In liver microsomes ferrous ions and ascorbic acid stimulated the non-enzymatic lipid peroxidation and concomitantly the epoxidation of aldrin. The results demonstrate that epoxidation of aldrin can be triggered by the iron initiated lipid peroxidation.

Aldrin↗

Alterations in granulation tissue growth induced in vivo by lymphocytes from adjuvant-diseased rats.

Lymph node cells from Lewis and Wistar rats, treated 9 or 11 days previously with Freund's complete (FCA) or incomplete adjuvant (FIA), were transferred into polyether sponges implanted subcutaneously into syngeneic, recipient rats. FCA-treated lymphocytes enhanced or reduced granuloma formation (measured after 8 days), when compared with FIA-treated controls, depending on the strain of mycobacterium present in the FCA. The stimulatory effects of lymphocytes from FCA-treated, Lewis rats were abolished by pre-incubation with mitomycin C (25 microgram/ml). Whole serum and isolated serum immunoglobulin from adjuvant-diseased rats had no effect on the sponge granulomas. These data confirm that cell-mediated immunity is involved in the articular granuloma formation of adjuvant arthritis.

Animals↗

Stimulation of granulation tissue formation by platelet-derived growth factor in normal and diabetic rats.

Subcutaneous implantation of Hunt-Schilling wound chambers in rats induces a wound repair response causing the chamber first to fill with fluid and subsequently with connective tissue. The presence of a type I collagen gel encouraged a more rapid dispersion of cells throughout the chamber but had no effect on the rate of new collagen deposition. Addition of platelet-derived growth factor (PDGF; 50 ng/chamber) to the collagen-filled chambers caused an earlier influx of connective tissue cells, a marked increase in DNA synthesis, and a greater collagen deposition in the chamber during the first 2 wk after implantation. After 3 wk, however, the levels of collagen were similar in PDGF-supplemented and control chambers. Diabetic animals exhibited a decreased rate of repair which was restored to normal by addition of PDGF to the wound chamber. Combinations of PDGF and insulin caused an even more rapid increase in collagen deposition. These results suggest that the levels of various growth factors, particularly PDGF, may be limiting at wound sites and that supplementation of wounds with these factors can accelerate the rate of new tissue formation.

Animals↗