Ileocolonic Healing after Small Ileocecal Resection in Mice: NOD2 Deficiency Impairs Anastomotic Healing by Local Mechanisms.

Ileocecal resection (ICR) is frequently performed in Crohn's disease (CD). NOD2 mutations are risk factors for CD. Nod2 knockout (ko) mice show impaired anastomotic healing after extended ICR. We further investigated the role of NOD2 after limited ICR. C57B16/J (wt) and Nod2 ko littermates underwent limited ICR including 1-2 cm terminal ileum and were randomly assigned to vehicle or MDP treatment. Bursting pressure was measured on POD 5, and the anastomosis was analyzed for matrix turn-over and granulation tissue. Wound fibroblasts from subcutaneously implanted sponges were used for comparison. The M1/M2 macrophage plasma cytokines were analyzed. Mortality was not different between groups. Bursting pressure was significantly decreased in ko mice. This was associated with less granulation tissue but was not affected by MDP. However, anastomotic leak (AL) rate tended to be lower in MDP-treated ko mice (29% vs. 11%, p = 0.07). mRNA expression of collagen-1α (col1 α), collagen-3α (col3 α), matrix metalloproteinase (mmp)2 and mmp9 was increased in ko mice, indicating increased matrix turn-over, specifically in the anastomosis. Systemic TNF-α expression was significantly lower in ko mice. Ileocolonic healing is impaired in Nod2 ko mice after limited ICR by local mechanisms maybe including local dysbiosis.

Reconstructive Surgery for Intestinal Failure.

BACKGROUND: Intestinal failure (IF) in the adult is the result of a wide spectrum of disease. Acute mesenteric ischemia, postoperative short bowel due to a complicative course, and Crohn's disease are major causes of IF. Reconstructive surgery in the context of IF comprises a spectrum of procedures including stoma takedown, reversal of laparostomies, and closure of enteric fistulas. METHODS: This article is based on a PubMed-based literature search and personal experience in adult patients with IF. RESULTS: This review summarizes therapeutic options of reconstructive surgery in adult patients focusing on the main reasons of IF such as mesenteric ischemia, complicative previous surgery, and Crohn's disease. Indications and contraindications are discussed as well as the optimal time point of reconstructive surgery. CONCLUSION: This overview summarizes surgical aspects in a special cohort of patients with a rare disease entity necessitating an interdisciplinary approach.

Aging influences wound healing in patients with chronic lower extremity wounds treated in a specialized Wound Care Center.

With the dramatic increase in the aging population, the study and care of wounds in the elderly have become priority topics for both researchers and clinicians. The effects of aging on wound healing in humans have remained controversial. The study was a 5-year epidemiological evaluation of standardized data collected regularly during patients' visits at a specialized Wound Care Center with the aim to determine the key factors influencing the healing of chronic lower extremity wounds. In this analysis of 1,158 chronic wounds, the frequency of wound closure was statistically significantly lower in older patients compared with younger patients. The share of closed wounds decreased by nearly 25% in the elderly patients (>or=70 years). The relationship between the patient's age and the proportion of wound closure was nonlinear. The effect of aging on the frequency of wound closure of chronic wounds became clinically apparent after age 60. The chronicity of the wounds was illustrated by their recurrent nature, their long duration, the presence of multiple wounds, and the frequency of concurrent infection. Comorbidity was documented by the coprevalence of up to three underlying diseases related to impaired wound healing. The present study clearly showed that aging affects chronic wound healing negatively.

The impact of the Micro-Lightguide O2C for the quantification of tissue ischemia in diabetic foot ulcers.

OBJECTIVE: Tissue oxygen supply is crucial for wound healing. Especially in diabetic foot lesions, the chances for healing are mainly dependent on the presence or absence of ischemia. This study investigates the impact of the tissue O2 analysis system "O2C" for noninvasive quantification of tissue oxygenation in diabetic foot ulcer patients. RESEARCH DESIGN AND METHODS: O2C assessed relative blood flow (flow), flow velocity (velo), and hemoglobin concentration (rHb) and hemoglobin oxygenation (SO2) at 2 and 6 mm depth (means +/- SE). 1) Measurements were performed on intact skin of the forefoot and forearm of 20 healthy volunteers on 2 consecutive days. 2) Parameters were assessed on intact skin of the forefoot of diabetic foot ulcer patients (n=14). 3) Measurements were performed directly at the wound site in diabetic patients (n = 14). RESULTS: 1) Flow, velo, rHb, and SO2 at 2 and 6 mm depth were not significantly different when measured at 2 consecutive days. 2) There were no significant differences between diabetic subjects and healthy volunteers. Only flow in 6 mm depth was significantly higher in diabetic subjects (75 +/- 13 vs. 51 +/- 0.4 arbitrary units [AU], P <0.05). When diabetic foot ulcer patients were split into healers and nonhealers, initial readings of SO2 at 2 mm (32 +/- 6 vs. 44 +/- 3%, P <0.05) and flow in 6 mm (28 +/- 1 vs. 51 +/- 0.6 AU, P <0.05) were significantly reduced in nonhealers compared with control subjects, whereas in healers flow in 6 mm (70 +/- 0.6 vs. 51 +/- 0.6 AU, P <0.05) was significantly higher than that in control subjects. 3) Initial SO2, rHb, flow, and velo were significantly lower in nonhealing compared with healing wounds. CONCLUSIONS: O2C is a new reliable and valid method for noninvasive measurement of tissue oxygenation and microvascular blood flow in patients with diabetic foot ulcers.

Nitric oxide and wound healing.

Nitric oxide is a short-lived free radical that acts at the molecular, cellular, and physiologic level. Since its discovery almost 20 years ago it has proven itself as an important element in wound healing. This review highlights many of the important aspects of nitric oxide in wound healing, including a review of the basic biology of nitric oxide, its role as part of the cytokine cascade and as a promoter of angiogenesis, as well as its more recently elucidated role in apoptosis.

Arginine physiology and its implication for wound healing.

Arginine is a basic amino acid that plays several pivotal roles in cellular physiology. Like any amino acid, it is involved with protein synthesis, but it is also intimately involved with cell signaling through the production of nitric oxide and cell proliferation through its metabolism to ornithine and the other polyamines. Because of these multiple functions, arginine is an essential substrate for wound healing processes. Numerous studies have shown that arginine supplementation can lead to normalization or improvement of healing. This article reviews the basic biochemistry and cell signaling within which arginine performs its functions. In particular, the requirement for this amino acid in tissue repair is highlighted.

Repair of full-thickness bowel injury.

OBJECTIVE: Colon surgery is more and more often performed in complex situations such as after trauma, under immunosuppression, or in the elderly. Even under optimal conditions, anastomosis fails in certain situations. The objective of this study was to demonstrate the normal phases of bowel healing and to review the local and systemic factors affecting healing with special attention to critical care variables such as major surgery, acute hemorrhage, and infections. DATA SOURCE: MEDLINE cited and/or published articles. DESIGN: Review analysis. RESULTS: Colon healing is a structured cascade of different phases that can be affected by a multitude of local (infection, ischemia) and systemic (diabetes, malnutrition, anemia, hypothermia, trauma) factors. The normal phases of repair, the resulting bursting pressure as an experimental index of healing, and the available published data on local and systemic factors affecting healing are summarized. CONCLUSION: Several local and systemic factors negatively affect bowel healing; there is still a small portion of patients who fail to heal, suggesting that intrinsic factors need to be analyzed.

Supplemental L-arginine enhances wound healing in diabetic rats.

L-arginine has been shown to enhance wound strength and collagen deposition in rodents and humans. Diabetes mellitus, which impairs wound healing, is accompanied by a reduction in nitric oxide at the wound site. The amino acid L-arginine is the only substrate for nitric oxide synthesis. We sought to determine whether supplemental L-arginine can restore the impaired wound healing of diabetic rats. Fifty-six male Lewis rats were used in this study, of which twenty-nine rats were rendered diabetic 7 days prior to surgery with intraperitoneal streptozotocin. Twenty-seven untreated rats served as controls. Animals underwent a dorsal skin incision with implantation of polyvinyl-alcohol sponges. Sixteen diabetic and 14 normal rats received 1 g/kg/day of L-arginine by injection, while the remainder received saline injections only. Animals were euthanized 10 days postwounding, and their wounds were analyzed for breaking strength. The wound sponges were assayed for total hydroxyproline and nitrite/nitrate content. Plasma and wound fluid concentrations of L-arginine, ornithine, and citrulline were determined. Wound sponge RNA was extracted and subjected to Northern blot analysis for procollagen I and III. Diabetic wounds had greatly decreased breaking strengths compared with controls. L-arginine significantly enhanced wound breaking strengths in both control (+23%) and diabetic animals (+44%), and also increased wound hydroxyproline levels in both diabetic (+40%) and control animals (+24%) as compared to their saline-treated counterparts. mRNA for procollagen I and III were elevated by L-arginine treatment in both diabetic rats and controls. Treatment with L-arginine significantly increased wound fluid nitrite/nitrate levels in diabetic animals. The data show that the impaired healing of diabetic wounds can be partially corrected by L-arginine supplementation, and that this effect is accompanied by enhanced wound nitric oxide synthesis.

L-Arginine supplementation enhances diabetic wound healing: involvement of the nitric oxide synthase and arginase pathways.

Diabetes impairs wound healing and there are few therapeutic options to reverse it. Previous work has demonstrated the importance of nitric oxide for successful wound healing. In diabetes, NO synthesis is reduced in the wound milieu. The amino acid L-arginine is the only substrate for NO synthesis. We hypothesized that L-arginine supplementation would enhance wound healing by restoring NO synthesis. Thirty-six male Sprague-Dawley rats (body weight, 225 to 250 g) were separated in 4 groups: 20 rats were rendered diabetic 7 days prior to wounding by intraperitoneal streptozotocin (STZ) injection (70 mg/kg). Sixteen rats served as controls. Half of the animals of each group received 1 g/kg supplemental L-arginine administered by gavage twice daily. Control rats were gavaged with water. Treatment was started 3 days before wounding. All rats underwent a dorsal skin incision and subcutaneous implantation of polyvinyl alcohol (PVA) sponges. The rats were killed 10 days post wounding and wound breaking strength, hydroxyproline content of the sponges, nitrite/nitrate (NO(x)) concentration, arginase activity, and amino acid composition of the wound fluid and plasma were analyzed. Wound fluid NO(x) concentrations and wound breaking strength were significantly reduced in the diabetic group compared to the controls. L-Arginine treatment restored diabetic NO(x) levels toward normal values and significantly enhanced wound breaking strength. Wound fluid arginase activity and ornithine concentrations were significantly lower in the diabetic animals but unaffected by treatment. The data demonstrate that the impaired NO synthesis in the diabetic wound milieu can at least partially be reversed by arginine supplementation. In view of previous results on the importance of NO for wound healing, the data suggest that arginine supplementation restores impaired healing in this acute wound model by normalizing the NO pathway but without affecting arginase activity.

Upregulation of arginase expression in wound-derived fibroblasts.

BACKGROUND: Wound-derived fibroblasts (WFBs) are phenotypically different from normal dermal fibroblasts (NFBs). We have previously shown that the wound phenotype correlates with expression of the inducible isoform of nitric oxide synthase (iNOS) in fibroblasts. l-Arginine is the sole substrate for iNOS. Arginase is an alternative pathway of l-arginine metabolism in wounds. To clarify the role of l-arginine in wound healing, we investigated arginase expression and activity in WFB. METHODS: Male Lewis rats underwent dorsal skin incisions and subcutaneous PVA sponge implantation. WFBs were harvested from sponges retrieved at different days postimplantation. Normal fibroblasts were obtained from uninjured skin by an explant technique. Arginase activity was measured by newly formed urea (nmol/min/mg protein) and protein expression was detected by Western blotting using specific antibodies for type I (AI) and type II (AII). The effect of transforming growth factor beta1 (TGF-beta1), interleukin-4 (IL-4), lipopolysaccharide, and wound fluid on arginase activity was also investigated. RESULTS: WFB arginase activity was significantly elevated compared with NFB activity at all times postwounding. This was paralleled by increased AI protein expression by Western blotting. AII was not detectable. TGF-beta and IL-4 significantly increased arginase activity and protein expression whereas lipopolysaccharide and wound fluid did not affect it. CONCLUSIONS: The upregulation of the arginase expression in WFB underlines the distinct regulation of l-arginine metabolism in WFBs. Further work is needed to elucidate the functional implications.

Role of nitric oxide in wound repair.

After injury, wound healing is essential for recovery of the integrity of the body. It is a complex, sequential cascade of events. Nitric oxide (NO) is a small radical, formed from the amino acid L-arginine by three distinct isoforms of nitric oxide synthase. The inducible isoform (iNOS) is synthesized in the early phase of wound healing by inflammatory cells, mainly macrophages. However many cells participate in NO synthesis during the proliferative phase after wounding. NO released through iNOS regulates collagen formation, cell proliferation and wound contraction in distinct ways in animal models of wound healing. Although iNOS gene deletion delays, and arginine and NO administration improve healing, the exact mechanisms of action of NO on wound healing parameters are still unknown. The current review summarizes what is known about the role of NO in wound healing and points out path for further research.