WHS guidelines for the treatment of pressure ulcers-2023 update

The major populations at risk for developing pressure ulcers are older adults who have multiple risk factors that increase their vulnerability, people who are critically ill and those with spinal cord injury/disease. The reported prevalence of pressure ulcers in the United States is 2.5 million. However, this estimate is derived from acute care facilities and does not include people who are living at home or in nursing facilities. Despite the implementation of hospital and facility-based preventive measures, the incidence of pressure ulcers has not decreased in decades. In addition to the burden of pain, infection and death, it is estimated that hospital-acquired pressure ulcers cost the health system $26.8 billion annually with over 50% of the cost attributed to treating Stage 3 and 4 pressure injuries. Thus, it is critical to examine the literature and develop guidelines that will improve the outcomes of this complex and costly condition. This guideline update is a compendium of the best available evidence for the treatment of Pressure Ulcers published since the last update in 2015 and includes a new section based on changing demographics entitled 'Palliative wound care for seriously ill patients with pressure ulcers'. The overall goal of the Wound Healing Society Guideline project is to present clear, concise and commercial free guidelines that clinicians can use to guide care, that researchers can use to develop studies that will improve treatment and that both clinicians and researchers can use to understand the gaps in our knowledge base.

Changes in the negative logarithm of end-tidal hydrogen partial pressure indicate the variation of electrode potential in healthy Japanese subjects

Molecular hydrogen (H2) is produced by human colon microbiomes and exhaled. End-tidal H2 sampling is a simple method of measuring alveolar H2. The logarithm of the hydrogen ion (H+)/H2 ratio suggests the electrode potential in the solution according to the Nernst equation. As pH is defined as the negative logarithm of the H+ concentration, pH2 is defined as the negative logarithm of the H2 effective pressure in this study. We investigated whether changes in pH2 indicated the variation of electrode potential in the solution and whether changes in end-tidal pH2 could be measured using a portable breath H2 sensor. Changes in the electrode potential were proportional to ([Formula: see text]) in phosphate-buffered solution (pH = 7.1). End-tidal H2 was measured in the morning (baseline) and at noon (after daily activities) in 149 healthy Japanese subjects using a handheld H2 sensor. The median pH2 at the baseline was 4.89, and it increased by 0.15 after daily activities. The variation of electrode potential was obtained by multiplying the pH2 difference, which suggested approximately + 4.6 mV oxidation after daily activities. These data suggested that changes in end-tidal pH2 indicate the variation of electrode potential during daily activities in healthy human subjects.

The Economic Impact of Living Cell Tissue Products in Treating Diabetic Foot Ulcers and Venous Leg Ulcers in Patients with Commercial Insurance: A Retrospective Matched-Cohort Study

OBJECTIVE

Previous studies demonstrated that costs paid on behalf of Medicare recipients for diabetic foot ulcers and venous leg ulcers treated with cellular and/or tissue-based products (CTPs) varied in part based on the CTP chosen. This study extends previous work to determine how costs vary when paid by commercial insurance carriers.

METHODS

A retrospective matched-cohort intent-to-treat design was used to analyze commercial insurance claims data between January 2010 and June 2018. Study participants were matched using Charlson Comorbidity Index, age, sex, type of wound, and geographic location within the US. Patients treated with a bilayered living cell construct (BLCC), dermal skin substitute (DSS), or cryopreserved human skin (CHSA) were included.

RESULTS

Wound-related costs and number of CTP applications were significantly lower for CHSA relative to BLCC and DSS at all time intervals (60, 90, and 180 days and 1 year after first application of the CTP). Further, CHSA was associated with significantly fewer amputations at 1 year relative to DSS (14.9% vs 19.7%, P = .03).

CONCLUSIONS

There was a statistically significant reduction in cost of treating diabetic foot ulcers (BLCC, DSS, CHSA) and venous leg ulcers (BLCC, CHSA) with CHSA as compared with the other CTPs. These findings are attributed to fewer applications, lower wound care costs, and comparable or reduced incidence of amputation. These commercial insurance data are consistent with prior studies that examined Medicare expenditures.

Reactive oxygen species-degradable polythioketal urethane foam dressings to promote porcine skin wound repair

Porous, resorbable biomaterials can serve as temporary scaffolds that support cell infiltration, tissue formation, and remodeling of nonhealing skin wounds. Synthetic biomaterials are less expensive to manufacture than biologic dressings and can achieve a broader range of physiochemical properties, but opportunities remain to tailor these materials for ideal host immune and regenerative responses. Polyesters are a well-established class of synthetic biomaterials; however, acidic degradation products released by their hydrolysis can cause poorly controlled autocatalytic degradation. Here, we systemically explored reactive oxygen species (ROS)-degradable polythioketal (PTK) urethane (UR) foams with varied hydrophilicity for skin wound healing. The most hydrophilic PTK-UR variant, with seven ethylene glycol (EG7) repeats flanking each side of a thioketal bond, exhibited the highest ROS reactivity and promoted optimal tissue infiltration, extracellular matrix (ECM) deposition, and reepithelialization in porcine skin wounds. EG7 induced lower foreign body response, greater recruitment of regenerative immune cell populations, and resolution of type 1 inflammation compared to more hydrophobic PTK-UR scaffolds. Porcine wounds treated with EG7 PTK-UR foams had greater ECM production, vascularization, and resolution of proinflammatory immune cells compared to polyester UR foam-based NovoSorb Biodegradable Temporizing Matrix (BTM)-treated wounds and greater early vascular perfusion and similar wound resurfacing relative to clinical gold standard Integra Bilayer Wound Matrix (BWM). In a porcine ischemic flap excisional wound model, EG7 PTK-UR treatment led to higher wound healing scores driven by lower inflammation and higher reepithelialization compared to NovoSorb BTM. PTK-UR foams warrant further investigation as synthetic biomaterials for wound healing applications.

The Effect of Comorbidities on Wound Healing

Wound healing is affected by several factors. Preexisting diagnoses may significantly alter, delay, or inhibit normal wound healing. This is most commonly seen with chronic disorders, such as diabetes and renal failure, but also occurs secondary to aging and substance abuse. Less commonly, genetic or inflammatory disorders are the cause of delayed wound healing. In some cases, it is not the illness, but the treatment that can inhibit wound healing. This is seen in patients getting chemotherapy, radiation, steroids, methotrexate, and a host of other medications. Understanding these processes may help treat or avoid wound healing problems.

Matched-cohort study comparing bioactive human split-thickness skin allograft plus standard of care to standard of care alone in the treatment of diabetic ulcers: A retrospective analysis across 470 institutions

This retrospective, matched‐cohort study analyzed 1,556 patients with diabetic ulcers treated at 470 wound centers throughout the United States to determine the effectiveness of a cryopreserved bioactive split‐thickness skin allograft plus standard of care when compared to standard of care alone. There were 778 patients treated with the graft in the treatment cohort, who were paired with 778 patients drawn from a pool of 126,864 candidates treated with standard of care alone (controls), by using propensity matching to create nearly identical cohorts. Both cohorts received standard wound care, including surgical debridement, moist wound care, and offloading. Logistic regression analysis of healing rates according to wound size, wound location, wound duration, volume reduction, exposed deep structures, and Wagner grade was performed. Amputation rates and recidivism at 3 months, 6 months, and 1 year after wound closure were analyzed. Diabetic ulcers were 59% more likely to close in the treatment cohort compared to the control cohort (p = 0.0045). The healing rate with the graft was better than standard of care across multiple subsets, but the most significant improvement was noted in the worst wounds that had a duration of 90‐179 days prior to treatment (p = 0.0073), exposed deep structures (p = 0.036), and/or Wagner Grade 4 ulcers (p = 0.04). Furthermore, the decrease in recidivism was statistically significant at 3 months, 6 months, and 1 year, with and without initially exposed deep structures (p < 0.05). The amputation rate in the treatment cohort was 41.7% less than that of the control cohort at 20 weeks (0.9% vs. 1.5%, respectively). This study demonstrated that diabetic ulcers treated with a cryopreserved bioactive split‐thickness skin allograft were more likely to heal and remain closed compared to ulcers treated with standard of care alone.

The Role of Vitamin A in Wound Healing

Vitamin A is an essential micronutrient that comes in multiple forms, including retinols, retinals, and retinoic acids. Dietary vitamin A is absorbed as retinol from preformed retinoids or as pro-vitamin A carotenoids that are converted into retinol in the enterocyte. These are then delivered to the liver for storage via chylomicrons and later released into the circulation and to its biologically active tissues bound to retinol-binding protein. Vitamin A is a crucial component of many important and diverse biological functions, including reproduction, embryological development, cellular differentiation, growth, immunity, and vision. Vitamin A functions mostly through nuclear retinoic acid receptors, retinoid X receptors, and peroxisome proliferator-activated receptors. Retinoids regulate the growth and differentiation of many cell types within skin, and its deficiency leads to abnormal epithelial keratinization. In wounded tissue, vitamin A stimulates epidermal turnover, increases the rate of re-epithelialization, and restores epithelial structure. Retinoids have the unique ability to reverse the inhibitory effects of anti-inflammatory steroids on wound healing. In addition to its role in the inflammatory phase of wound healing, retinoic acid has been demonstrated to enhance production of extracellular matrix components such as collagen type I and fibronectin, increase proliferation of keratinocytes and fibroblasts, and decrease levels of degrading matrix metalloproteinases.

Gastrointestinal symptoms in postural tachycardia syndrome: a systematic review

Gastrointestinal symptoms are among the most common complaints in patients with postural tachycardia syndrome (POTS). In some cases, they dominate the clinical presentation and cause substantial disabilities, including significant weight loss and malnutrition, that require the use of invasive treatment to support caloric intake. Multiple cross-sectional studies have reported a high prevalence of gastrointestinal symptoms in POTS patients with connective tissue diseases, such as Ehlers-Danlos, hypermobile type, and in patients with evidence of autonomic neuropathy. Previous studies that evaluated gastric motility in these patients reported a wide range of abnormalities, particularly delayed gastric emptying. The pathophysiology of gastrointestinal symptoms in POTS is likely multifactorial and probably depends on the co-morbid conditions. In patients with POTS and Ehlers-Danlos syndromes, structural and functional abnormalities in the gastrointestinal connective tissue may play a significant role, whereas in neuropathic POTS, the gastrointestinal tract motility and gut hormonal secretion may be directly impaired due to localized autonomic denervation. In patients with normal gastrointestinal motility but persistent gastrointestinal symptoms, gastrointestinal functional disorders should be considered. We performed a systematic review of the literature related to POTS and gastrointestinal symptoms have proposed possible mechanisms and discussed diagnosis and treatment approaches for delayed gastric emptying, the most common gastrointestinal abnormality reported in patients with POTS.

Nutrition and Lower Extremity Ulcers: Causality and/or Treatment

The association between malnutrition, impaired wound healing, and the presence of chronic wounds has been recognized for a long time. It is widely believed that the lack of adequate nutrition increases the risk of developing wounds which have a great likelihood of progressing to chronicity due to lack of appropriate healing responses. This risk is particularly high in the aging population. For the individual patient, as well as patient populations, the diagnosis of malnutrition has been in dispute; further, there is lack of agreement of when and how to intervene nutritionally in those with wounds or healing deficits. This article examines the relationship of nutritional status with the presence and clinical evolution of leg ulcers in humans, focusing on diabetic and venous leg ulcers; we will further review the effect of nutritional therapy on the outcome of these ulcers.

Proline Precursors and Collagen Synthesis: Biochemical Challenges of Nutrient Supplementation and Wound Healing

Wound healing is a complex process marked by highly coordinated immune fluxes into an area of tissue injury; these are required for re-establishment of normal tissue integrity. Along with this cascade of cellular players, wound healing also requires coordinated flux through a number of biochemical pathways, leading to synthesis of collagen and recycling or removal of damaged tissues. The availability of nutrients, especially amino acids, is critical for wound healing, and enteral supplementation has been intensely studied as a potential mechanism to augment wound healing-either by increasing tensile strength, decreasing healing time, or both. From a practical standpoint, although enteral nutrient supplementation may seem like a reasonable strategy to augment healing, a number of biochemical and physiologic barriers exist that limit this strategy. In this critical review, the physiology of enteral amino acid metabolism and supplementation and challenges therein are discussed in the context of splanchnic physiology and biochemistry. Additionally, a review of studies examining various methods of amino acid supplementation and the associated effects on wound outcomes are discussed.

Arginine-Dual roles as an onconutrient and immunonutrient

Arginine is an important player in numerous biologic processes and studies have demonstrated its importance for cellular growth that becomes limiting in states of rapid turnover (e.g., malignancy). Thus, arginine deprivation therapy is being examined as an adjuvant cancer therapy, however, arginine is also necessary for immune destruction of malignant cells. Herein we review the data supporting arginine deprivation or supplementation in cancer treatment and the currently registered trials aimed at understanding these divergent strategies. J. Surg. Oncol. 2017;115:273-280. © 2016 Wiley Periodicals, Inc.

Nutritional Aspects of Gastrointestinal Wound Healing

Significance: Although the wound healing cascade is similar in many tissues, in the gastrointestinal tract mucosal healing is critical for processes such as inflammatory bowel disease and ulcers and healing of the mucosa, submucosa, and serosal layers is needed for surgical anastomoses and for enterocutaneous fistula. Failure of wound healing can result in complications including infection, prolonged hospitalization, critical illness, organ failure, readmission, new or worsening enterocutaneous fistula, and even death. Recent Advances: Recent advances are relevant for the role of specific micronutrients, such as vitamin D, trace elements, and the interplay between molecules with pro- and antioxidant properties. Our understanding of the role of other small molecules, genes, proteins, and macronutrients is also rapidly changing. Recent work has elucidated relationships between oxidative stress, nutritional supplementation, and glucose metabolism. Thresholds have also been established to define adequate preoperative nutritional status. Critical Issues: Further work is needed to establish standards and definitions for measuring the extent of wound healing, particularly for inflammatory bowel disease and ulcers. In addition, a mounting body of evidence has determined the need for adequate preoperative nutritional supplementation for elective surgical procedures. Future Directions: A large portion of current work is restricted to model systems in rodents. Therefore, additional clinical and translational research is needed in this area to promote gastrointestinal wound healing in humans, particularly those suffering from critical illness, patients with enterocutaneous fistula, inflammatory bowel disease, and ulcers, and those undergoing surgical procedures.

Immunonutrition: Role in Wound Healing and Tissue Regeneration

Significance: The role of immunonutrition in wound healing has been an area of both interest and controversy for many years. Although deficiencies in certain nutrients have long been known to impair healing, supplementation of specific immune modulating nutrients has not consistently yielded improvements in wound healing. Still, the prospect of optimizing nutrition to assist the immune system in wound repair bears great significance in both medical and surgical fields, as the costs of wound care and repair cannot be ignored. Recent Advances: Recent studies have rekindled efforts to elucidate the roles of specific immunonutrients, and we now have a better understanding of the conditionally essential role of various nutrients such as arginine, which becomes essential in certain clinical situations such as for the trauma patient or patients at high risk for malnutrition. Immunonutrition in its current formulation usually includes supplementation with arginine, glutamine, omega-3 fatty acids, vitamins, and trace minerals, and its use has often been associated with decreased infectious complications and sometimes with improvements in wound healing. Critical Issues: A key to understanding the role of immunonutrition in wound healing is recognizing the distinct contributions and importance of the various elements utilized. Future Directions: Critical areas for future study include identifying the specific populations, timing, and ideal composition of immunomodulating diets in order to optimize the wound healing process.

Excessive nitric oxide impairs wound collagen accumulation

BACKGROUND

Nitric oxide (NO) plays a major regulatory role in wound collagen synthesis. We hypothesized that this regulatory role is tightly controlled by the levels of NO in the wound environment and that supranormal wound NO generation impairs wound collagen accumulation.

MATERIALS AND METHODS

We used the model of turpentine-induced granuloma in male Sprague-Dawley rats as a sterile inflammatory stimulus generating large amounts of NO. In this environment, NO generation increased by 260%, whereas collagen deposition was significantly reduced by 38.5% (729.7 ± 81.5 versus 449.4 ± 76.3 μg hydroxyproline/100 mg sponge, P<0.05). Inhibition of NO synthase activity using 300 mM L-N6-(1-iminoethyl)-lysine, a highly potent and selective inhibitor of inducible NO synthase, significantly reduced NO elevation by 43.3% and increased wound collagen deposition by 37.3% (P<0.05). These effects occurred without any anti-inflammatory effects of L-N6-(1-iminoethyl)-lysine as assessed by the white blood cell counts and levels of interleukins 1 and 6.

CONCLUSIONS

The data show that high levels of NO within the wound environment significantly reduce wound collagen deposition. Inhibition of NO generation restores collagen levels to normal levels. The regulatory effects of NO on wound collagen appear to be highly correlated with the amount of NO generated.

Arginase inhibition promotes wound healing in mice

OBJECTIVE

Arginase plays important regulatory roles in polyamine, ornithine, and nitric oxide syntheses. However, its role in the healing process has not been delineated. In this study, we used a highly potent and specific inhibitor of arginase, namely 2(S)-amino-6-boronohexanoic acid NH4 (ABH) to evaluate the role of arginase function in wound healing.

MATERIALS AND METHODS

ABH or saline was applied topically to full thickness, dorsal, excisional wounds in C57BL/6 mice every 8 hours for 14 days post surgery and the rate of wound closure was estimated planimetrically. Wound tissue was harvested from mice sacrificed on postoperative days 3 and 7 and examined histologically. The extent of epithelial, connective, and granulation tissue present within the wound area was estimated histomorphometrically. The effect of ABH on wound arginase activity, production of nitric oxide metabolites (NO(x)), and presence of smooth muscle actin positive cells (myofibroblasts) was evaluated.

RESULTS

While arginase activity was inhibited in vivo, the rate of wound closure significantly increased 7 days post-surgery, (21 ± 4%: P < .01; Student t test) in ABH treated animals. This was accompanied by an early increase in wound granulation tissue and accumulation of NO(x) followed by enhanced re-epithelialization and localization of myofibroblasts beneath the wound epithelium.

CONCLUSION

Arginase inhibition improves excisional wound healing and may be used to develop therapeutics for early wound closure.

Peptide inhibitors of MK2 show promise for inhibition of abdominal adhesions

BACKGROUND

Abdominal adhesions are a common side effect of surgical procedures with complications including infertility, chronic pain, and bowel obstruction, which may lead to the need for surgical lyses of the adhesions. Mitogen-activated protein kinase-activated protein kinase 2 (MK2) has been implicated in several diseases, involving inflammation and fibrosis. Thus, the development of a cell-penetrating peptide (CPP) that modulates MK2 activity may confer therapeutic benefit after abdominal surgery in general and more specifically after bowel anastomosis.

METHODS

This study evaluated the function of a CPP inhibitor of MK2 in human mesothelial cells and in a rat bowel anastomosis model. To determine IC50 and basic specificity, kinase inhibition was performed using a radiometric assay. Enzyme-linked immunoassay (ELISA) was used to evaluate interleukin-6 (IL-6) expression in response to IL-1β and tumor necrosis factor-α (TNF-α) stimulation in vitro to validate MK2 kinase inhibition. Following bowel anastomosis (10 rats for each control and treatment at 4 and 10 d), the rats were evaluated for weight loss, normal healing (colonic burst strength and hydroxyproline content at the anastomosis), and number and density of adhesions.

RESULTS

The IC50 of the MK2 inhibitor peptide (22 μM) was similar to that of the nonspecific small molecule rottlerin (IC50 = 5 μM). The MK2 inhibitor peptide was effective at suppressing IL-1β and TNF-α stimulated IL-6 expression in mesothelial cells. In vivo, the MK2 inhibitor peptide was effective at suppressing both the density and number of adhesions formed as a result of bowel an anastamosis. Importantly, the peptide had no negative effect on normal healing.

CONCLUSIONS

In conclusion, the peptide inhibitor of MK2, MMI-0100, has the potential to significantly reduce inflammation through suppression of inflammatory cytokine expression and showed promise as a therapeutic for abdominal adhesions.

Intra-abdominal healing: gastrointestinal tract and adhesions

The abdominal cavity represents one of the most active areas of surgical activity. Surgical procedures involving the gastrointestinal (GI) tract are among the most common procedures performed today. Healing of the GI tract after removal of a segment of bowel and healing of the peritoneal surfaces with subsequent adhesion formation remain vexing clinical problems. Interventions to modify both the responses are myriad, yet a full understanding of the pathophysiology of these responses remains elusive. Different aspects of GI and peritoneal healing, with associated factors, are discussed in this article.

Complex wounds and their management

Complex wounds present a challenge to both the surgeon and patient in operative management, long-term care, cosmetic outcome, and effects on lifestyle, self-image, and general health. Each patient with complex wounds usually manifests multiple risk factors for their development. This article focuses on complex wounds involved with traumatic and orthopedic blunt or penetrating injuries, particularly in the extremities, as well as massive soft tissue infections including necrotizing fasciitis, gas gangrene, and Fournier gangrene. The principles of management of complex wounds involve assessing the patient's clinical status and the wound itself, appropriate timing of intervention, providing antibiotic therapy when necessary, and planning and executing surgical therapy, including the establishment of a clean wound bed and closure/reconstructive strategies.

Effect of preinjury statin use on mortality and septic shock in elderly burn patients

BACKGROUND

Premorbid statin use has been associated with decreased mortality in septic and trauma patients. This has been ascribed to the pleiotropic, anti-inflammatory effects of HMG-CoA reductase inhibitors. This association has not been investigated in burn victims.

METHODS

A retrospective review of 223 consecutive patients, aged 55 years and older admitted to Vanderbilt University Regional Burn Center from January 2006 to December 2008, was performed. Multivariate regression analysis determined odds ratios of death and sepsis by statin use, adjusting for cardiovascular comorbidities.

RESULTS

Of 223 patients, 70 (31.4%) were taking statins before admission. Mean age and mean total body surface area burn were not significantly different by statin use. The odds ratio of inhospital death was 0.17 (95% confidence interval 0.05-0.57; p = 0.004) if on statins. The odds ratio of mortality when stratified by cardiovascular comorbidities did not change. Sepsis developed in 30 patients (13.5%), with an odds ratio in statin users of 0.50 (95% confidence interval 0.20-1.30; p = 0.155).

CONCLUSION

Preinjury statin use was associated with an 83% reduction in the odds of death after thermal injury. The odds of sepsis decreased by 50%, although not statistically significant. Further study is warranted to investigate the potential benefits of statin therapy in the management of burn victims.

Acute wounds accelerate tumorigenesis by a T cell-dependent mechanism

We investigated the influence of acute wounding on tumor growth in a syngeneic mouse breast cancer model. Metastatic mouse breast cancer cells (4T1) were orthotopically injected into the mammary fat pads of BALB/c mice, and animals were wounded locally by full thickness dermal incisions above the mammary fat pads or remotely above the scapula 9 days later. Local, but not remote, wounding increased tumor size when compared with sham treatment. Injection of wound fluid close to the tumor site increased tumor growth, whereas in vitro wound fluid compared with serum increased the proliferation rate of 4T1 cells. Our results show that wound stroma can unfavorably influence growth of nearby tumors. This effect is T cell-dependent, as local wounding had no effect on tumor growth in nu/nu mice. The effect of wounding on tumor growth can be mimicked by acellular wound fluid, suggesting that T cells secrete or mediate secretion of cytokines or growth factors that then accelerate tumor growth. Here, we define an experimental model of wound-promoted tumor growth that will enable us to identify mechanisms and therapeutic targets to reduce the negative effect of tissue repair on residual tumors.

Proline precursors to sustain Mammalian collagen synthesis

Biochemically, one-third of the collagen molecule is composed of glycine. The next largest amino acid component is formed by proline (PRO) and hydroxyproline, which together comprise approximately 23% of the collagen molecule. The best method to support wound collagen biosynthesis is to provide adequate host nutrition, assuring adequate provision of calories and protein. However, despite adequate nutrition, clinically, there is a need to enhance collagen synthesis and research has focused on methods to enhance collagen precursor availability. PRO biosynthesis is related to both the citric acid cycle and the urea cycle. During the early phases of wound healing, wound fluid PRO levels are at least 50% higher than plasma levels, suggesting active import of PRO into the wound. Providing additional PRO in the diet to enhance PRO bioavailability for collagen biosynthesis does not result in increased collagen accumulation. Provision of other citric cycle precursors such as glutamine also does not enhance wound collagen synthesis. In looking at other PRO biosynthetic pathways, the arginine (ARG) --> ornithine (ORN) --> glutamic semialdehyde --> PRO pathway looks the most promising. ARG administration in quantities above those required for growth and reproduction results in a marked enhancement in wound collagen deposition. This effect is also shared by ORN, which cannot replace ARG for growth requirement but shares many of its biological and pharmacological activities. Several mechanisms have been postulated to explain the positive effect of ARG on wound healing, although none have been firmly proven. In conclusion, ARG and ORN supplementation are most effective in increasing collagen deposition, but whether this is accomplished by conversion to PRO is uncertain.

Proline precursors to sustain Mammalian collagen synthesis

Biochemically, one-third of the collagen molecule is composed of glycine. The next largest amino acid component is formed by proline (PRO) and hydroxyproline, which together comprise approximately 23% of the collagen molecule. The best method to support wound collagen biosynthesis is to provide adequate host nutrition, assuring adequate provision of calories and protein. However, despite adequate nutrition, clinically, there is a need to enhance collagen synthesis and research has focused on methods to enhance collagen precursor availability. PRO biosynthesis is related to both the citric acid cycle and the urea cycle. During the early phases of wound healing, wound fluid PRO levels are at least 50% higher than plasma levels, suggesting active import of PRO into the wound. Providing additional PRO in the diet to enhance PRO bioavailability for collagen biosynthesis does not result in increased collagen accumulation. Provision of other citric cycle precursors such as glutamine also does not enhance wound collagen synthesis. In looking at other PRO biosynthetic pathways, the arginine (ARG) --> ornithine (ORN) --> glutamic semialdehyde --> PRO pathway looks the most promising. ARG administration in quantities above those required for growth and reproduction results in a marked enhancement in wound collagen deposition. This effect is also shared by ORN, which cannot replace ARG for growth requirement but shares many of its biological and pharmacological activities. Several mechanisms have been postulated to explain the positive effect of ARG on wound healing, although none have been firmly proven. In conclusion, ARG and ORN supplementation are most effective in increasing collagen deposition, but whether this is accomplished by conversion to PRO is uncertain.

Laparoscopy-assisted distal gastrectomy for gastric cancer

OBJECTIVE

The purpose of this study was to evaluate the safety and value of laparoscopy-assisted distal gastrectomy (LADG) for early stage gastric cancer (stages IA, IB, and II).

MATERIALS AND METHODS

We retrospectively assessed 101 cases treated by LADG and compared to 49 contemporaneous cases treated by open distal gastrectomy (DG) between 2001 and 2006. Clinical variables, such as tumor diameter, operation time, blood loss, number of lymph nodes dissected, and length of stay were investigated.

RESULTS

Tumor size (mm) was significantly smaller in the LADG group (p < 0.0001). Although operation time (min) in the two groups was similar (278 +/- 57 vs. 268 +/- 55), mean blood loss was significantly higher in the DG group (139 +/- 181 vs. 460 +/- 301, p < 0.0001). Fewer lymph nodes were harvested in the LADG group (27 +/- 14 vs. 34 +/- 19, p = 0.012). Hospital stay was longer in the DG group (13.3 +/- 8.5 vs. 16.7 +/- 10.5, p = 0.034). There was no mortality in either group. Postoperative surgical complications occurred in six (6%) of the LADG and four (8%) of the DG.

CONCLUSIONS

The authors conclude that laparoscopy-assisted distal gastrectomy is a safe and useful operation for early-stage gastric cancers. If patients are selected properly, laparoscopy-assisted distal gastrectomy can be a curative and minimally invasive treatment for gastric cancer.

Phase I trial on the safety of topical rhVEGF on chronic neuropathic diabetic foot ulcers

OBJECTIVE

To assess the safety/tolerability and perform a preliminary efficacy evaluation of a multiple-dosing regimen of recombinant human vascular endothelial growth factor (VEGF165 or rhVEGF; telbermin) applied topically to chronic diabetic neuropathic foot ulcers.

METHOD

Subjects with type 1 or 2 diabetes mellitus were randomised to receive either topical applied telbermin (72 microg/cm2) (n=29) or placebo (n=26) treatment to the foot ulcer surface in conjunction with standard ulcer care. Subjects received treatment every 48 hours (maximum three doses per week) for up to six weeks. Weekly 35mm photography, quantitative planimetry and physical examinations documented the ulcer appearance, surface area and stage. Safety endpoints included incidence of clinically significant hypotension, adverse events and ulcer infection. Exploratory efficacy endpoints included percentage reduction in total ulcer surface area, incidence of complete ulcer healing and time to complete ulcer healing.

RESULTS

Incidence of adverse events was comparable in the two treatment groups. None of the adverse events were attributed to study drug, and no hypotension was observed as a result of telbermin treatment. Occurrence of infected study ulcers appeared to be balanced between the treatment groups. Positive trends suggestive of potential signals of biological activity were observed for incidence of complete ulcer healing (41.4% telbermin versus 26.9% placebo at day 43 [P=0.39]) and time to complete ulcer healing (25th percentile of 32.5 days telbermin versus 43.0 days placebo [log-rank P=0.13]).

CONCLUSION

The topical application of telbermin 72 microg/cm2 three times a week for up to six weeks appeared to be well tolerated. Further studies are required to characterise the safety/efficacy of telbermin more completely.

Use of exogenous arginine in multiple organ dysfunction syndrome and sepsis

Given the multiple biological, metabolic, and pharmacologic effects of supplemental arginine, much effort has been devoted to defining its role in numerous clinical conditions. Herein, we review the multiple pathways of arginine metabolism with its various enzyme systems; the effect of arginine on nutrition, healing, and immune system; and its clinical use. Sepsis has been postulated to be an arginine-deficient state and/or a syndrome with elevated levels of nitric oxide. So-called immunonutritional formulations containing various nutritional components have been used most often, yet the effects often are attributed to arginine alone. Such conclusions led to guidelines recommending against the use of arginine-supplemented diets in critically ill patients. While caution in the face of a lack of evidence for benefit in sepsis is commended, well-defined studies examining arginine monotherapy in the context of full nutritional support should be carried out so as to define the possible clinical uses of arginine in critically ill and septic patients.

Supplemental l-arginine enhances wound healing following trauma/hemorrhagic shock

To determine whether parenteral L-arginine supplementation enhances the impaired wound healing of rats subjected to trauma/hemorrhagic shock. Impaired wound healing after trauma and shock has been documented experimentally and clinically. L-arginine has been shown to enhance wound strength and collagen synthesis in rodents and humans. Its efficacy under conditions of impaired wound healing is less well defined. Forty-eight male Lewis rats were used in this study. Using a well-defined model, 24 rats underwent trauma/hemorrhagic shock before wounding. Twenty-four untreated rats served as controls. All animals underwent a dorsal skin incision with implantation of polyvinyl-alcohol sponges. Half of the animals in each group were assigned to receive 1 g/kg/day of L-arginine by intraperitoneal injection in three divided doses, while the other half received saline injections only. Animals were sacrificed 10 days postwounding, and wound-breaking strength (WBS) and wound sponge total hydroxyproline (OHP) and nitrite/nitrate (NO(x)) content were determined. Wound sponge RNA was collected and subjected to Northern blot analysis for procollagens I and III. Trauma/hemorrhage greatly decreased WBS with a concomitant diminution in collagen (OHP) deposition. L-arginine significantly enhanced WBS (19%) and increased OHP (21%) levels in control animals as well as in rats subjected to trauma/hemorrhage (WBS +29%, OHP 40%) compared with their saline-treated counterparts. Procollagen I and III mRNA levels were elevated by L-arginine treatment in both trauma/hemorrhage and control rats. Arginine treatment had no effect on wound fluid and plasma NO(x). The data demonstrate that the impaired healing subsequent to trauma/hemorrhage can be greatly alleviated by L-arginine supplementation.

Exogenous pro-angiogenic stimuli cannot prevent physiologic vessel regression

BACKGROUND

In healing wounds, rising levels of vascular endothelial growth factor (VEGF) induce a period of robust angiogenesis. The levels of pro-angiogenic factors in the wound begin to decline just before a period of vascular regression, suggesting that these mediators are necessary to sustain vessel density. The purpose of this study was to determine if the maintenance of pro-angiogenic stimuli in the wound would prevent physiological vessel regression.

MATERIALS AND METHODS

A standard subcutaneous sponge wound model was modified by the addition of a mini-osmotic pump, allowing manipulation of the wound milieu by the addition of exogenous growth factors. After initial characterization of this model, exogenous VEGF (10 microg/mL), FGF (10 microg/mL), PDGF (10 microg/mL), or VEGF (10 microg/mL) plus FGF (10 microg/mL) were delivered to wounds and blood vessel density analyzed by immunohistochemistry.

RESULTS

VEGF administration resulted in a transient increase in wound vessel density (P < 0.05). None of the pro-angiogenic growth factors (VEGF, FGF, PDGF, VEGF/FGF) were able to prevent vascular regression (P = NS).

CONCLUSIONS

These findings suggest that the anti-angiogenic signals that mediate physiological vascular regression in wounds are strongly dominant over pro-angiogenic stimuli during the later phases of wound healing. Clinical manipulation of anti-angiogenic signals in addition to the currently used pro-angiogenic targets may be needed to achieve therapeutic modulation of blood vessel density.