Reepithelialization of experimental scalds effected by topically applied superoxide dismutase: controlled animal studies

Dexmedetomidine on the interplay of IL-6 and STAT3 pathways in adrenal gland damage-induced scalding burns in rats

Scalding burns are a common form of thermal injury that often leads to systemic complications. Pro-inflammatory cytokines like interleukin-6 (IL-6) and the activation of signal transducer and activator of transcription 3 (STAT3) pathways have been linked to the pathophysiology of organ damage caused by burns. This study aimed to investigate the potential therapeutic effects of dexmedetomidine, an α2-adrenergic receptor agonist with anti-inflammatory properties, on the interplay of IL-6 and STAT3 pathways in adrenal gland damage following scalding burns in rats. Twenty-eight rats were divided randomly into four groups. Rats in group 1 (n=7, control) were given only 0.9% intraperitoneal (i.p.) NaCl. Rats in group 2 (n=7, DEX) were exposed to 25°C water for 17 s on day 1 and received 100 mcg/kg/day dexmedetomidine i.p. for 3 days; for rats in group 3 (n=7, Burn), boiling water of 94°C was applied inside for 17 s. Rats in group 4 (n=7, Burn+DEX) were exposed to 94°C water for 17 s and received 100 mcg/kg/day dexmedetomidine i.p. for 3 days. Adrenal gland tissues were histopathological examined, and STAT3, IL-6, and TUNEL staining were performed using immunohistochemically. Our results revealed that scalding burns increased IL-6 and STAT3 expression in the adrenal glands of rats. Histological analysis demonstrated that dexmedetomidine administration ameliorated adrenal gland damage and reduced inflammatory cell infiltration. Our findings suggest that dexmedetomidine protects the adrenal glands in scalding burns. This protection appears to be mediated, at least in part, by its modulation of IL-6 and STAT3 pathways.

Enzymes for dermatological use

Skin is the ultimate barrier between body and environment and prevents water loss and penetration of pathogens and toxins. Internal and external stressors, such as ultraviolet radiation (UVR), can damage skin integrity and lead to disorders. Therefore, skin health and skin ageing are important concerns and increased research from cosmetic and pharmaceutical sectors aims to improve skin conditions and provide new anti-ageing treatments. Biomolecules, compared to low molecular weight drugs and cosmetic ingredients, can offer high levels of specificity. Topically applied enzymes have been investigated to treat the adverse effects of sunlight, pollution and other external agents. Enzymes, with a diverse range of targets, present potential for dermatological use such as antioxidant enzymes, proteases and repairing enzymes. In this review, we discuss enzymes for dermatological applications and the challenges associated in this growing field.

Antioxidant-biocompatible and stable catalase-based gelatin-alginate hydrogel scaffold with thermal wound healing capability: immobilization and delivery approach

Hydrogel-based matrix prepared using biopolymers is a new frontier of emerging platforms for enzyme immobilization for biomedical applications. Catalase (CAT) delivery can be effective in inhibiting reactive oxygen species (ROS)-mediated prolongation of the wound healing process. In this study, to improve CAT stability for effective application, gelatin(Gel)–alginate (Alg) biocompatible hydrogel (Gel–Alg), as immobilization support, was prepared using calcium chloride as an ionic cross-linker. High entrapment efficiency of 92% was obtained with 2% Gel and 1.5% Alg. Hydrogel immobilized CAT (CAT–Gel–Alg) showed a wide range of pH from 4 to 9 and temperature stability between 20 to 60 °C, compared to free CAT. CAT–Gel–Alg kinetic parameters revealed an increased K_m (24.15 mM) and a decreased V_max (1.39 µmol H₂O₂/mg protein min) × 10⁴. CAT–Gel–Alg retained 52% of its original activity after 20 consecutive catalytic runs and displayed improved thermal stability with a higher t_1/2 value (half-life of 100.43 vs. 46 min). In addition, 85% of the initial activity was maintained after 8 weeks’ storage at 4 °C. At 24 h after thermal injury, a statistically significant difference in lesion sizes between the treated group and the control group was reported. Finally, our findings suggest that the superior CAT–Gel–Alg stability and reusability are resonant features for efficient biomedical applications, and ROS scavenging by CAT in the post-burn phase offers protection for local treatment of burned tissues with encouraging wound healing kinetics.

The Yin and Yang dualistic features of autophagy in thermal burn wound healing

Burn healing should be regarded as a dynamic process consisting of two main, interrelated phases: (a) the inflammatory phase when neutrophils and monocytes infiltrate the injury site, through localized vasodilation and fluid extravasation, and (b) the proliferative-remodeling phase, which represents a key event in wound healing. In the skin, both canonical autophagy (induced by starvation, oxidative stress, and environmental aggressions) and non-canonical or selective autophagy have evolved to play a discrete, but, essential, “housekeeping” role, for homeostasis, immune tolerance, and survival. Experimental data supporting the pro-survival roles of autophagy, highlighting its Yang, luminous and positive feature of this complex but insufficient explored molecular pathway, have been reported. Autophagic cell death describes an “excessive” degradation of important cellular components that are necessary for normal cell function. This deadly molecular mechanism brings to light the darker, concealed, Yin feature of autophagy. Autophagy seems to perform dual, conflicting roles in the angiogenesis context, revealing once again, its Yin–Yang features. Autophagy with its Yin–Yang features remains the shadow player, able to decide quietly whether the cell survives or dies.

Nigella sativa and Its Active Compound, Thymoquinone, Accelerate Wound Healing in an In Vivo Animal Model: A Comprehensive Review

Nigella sativa (NS) has been reported to have a therapeutic effect towards skin wound healing via its anti-inflammatory, tissue growth stimulation, and antioxidative properties. This review examines all the available studies on the association of Nigella sativa (NS) and skin wound healing. The search was performed in Medline via EBSCOhost and Scopus databases to retrieve the related papers released between 1970 and March 2020. The principal inclusion criteria were original article issued in English that stated wound healing criteria of in vivo skin model with topically applied NS. The search discovered 10 related articles that fulfilled the required inclusion criteria. Studies included comprise different types of wounds, namely excisional, burn, and diabetic wounds. Seven studies unravelled positive results associated with NS on skin wound healing. Thymoquinone has anti-inflammatory, antioxidant, and antibacterial properties, which mainly contributed to wound healing process.

Novel pharmacotherapy for burn wounds: what are the advancements

INTRODUCTION

The prognosis for severe burns has improved significantly over the past 50 years. Meanwhile, burns have become an affliction mainly affecting the less well-developed regions of the world. Early excision and skin grafting has led to major improvements in therapeutic outcomes.

AREAS COVERED

The purpose of this article is to survey the use of pharmacotherapy to treat different pathophysiological complications of burn injury. The author, herein, discusses the use of drug treatments for a number of systemic metabolic disturbances including hyperglycemia, elevated catabolism, and gluconeogenesis.

EXPERT OPINION

Advancements in personalized and molecular medicine will make an impact on burn therapy. Similarities between severe burns and other critically ill patients will lead to cross-fertilization between different medical specialties. Furthermore, advances in stem cells and tissue regeneration will lead to improved healing and less lifelong disability. Indeed, research in new drug therapy for burns is actively progressing for many different complications.

Redox Profiling Reveals Clear Differences between Molecular Patterns of Wound Fluids from Acute and Chronic Wounds

Wound healing is a complex multiphase process which can be hampered by many factors including impaired local circulation, hypoxia, infection, malnutrition, immunosuppression, and metabolic dysregulation in diabetes. Redox dysregulation is a common feature of many skin diseases demonstrated by virtually all cell types in the skin with overproduction of reactive oxygen and nitrogen species. The objective of this study was to characterize the redox environment in wound fluids and sera from patients suffering from chronic leg ulcers (n = 19) and acute wounds (bulla fluids from second degree burns; n = 11) with serum data also compared to those from healthy volunteers (n = 7). Significantly higher concentrations of TNF-α, interleukine-8, vascular endothelial growth factor, and lactate dehydrogenase (measure of cell damage) were found in fluids from chronic wounds compared to acute ones. The extent of protein carbonylation (measure of protein oxidation), lipid peroxidation, and tyrosine nitration (indicator of peroxynitrite production) was similar in acute and chronic wound fluids, while radical scavenging activity and glutathione (GSH) levels were elevated in chronic wound fluids compared to acute wounds. Sera were also assessed for the same set of parameters with no significant differences detected. Nitrotyrosine (the footprint of the potent oxidant peroxynitrite) and poly(ADP-ribose) (the product of the DNA damage sensor enzyme PARP-1) could be detected in wound biopsies. Our data identify multiple signs of redox stress in chronic wounds with notable differences. In chronic wounds, elevations in antioxidant levels/activities may indicate compensatory mechanisms against inflammation. The presence of nitrotyrosine and poly(ADP-ribose) in tissues from venous leg ulcers indicate peroxynitrite production and PARP activation in chronic wounds.

Monitoring wound healing in minor burns-A novel approach

Assessment of minor burn wound closure is predominately determined by visual inspection and clinical specialist assessment, which remains largely a subjective analysis and results may vary depending on the clinician's experience. Bioimpedance spectroscopy (BIS) is an instrument that has a demonstrated ability to objectively monitor the wound healing process in various patient populations but has not yet been used in acute burn wounds. The aim of the pilot study was to examine whether the BIS technique is a valid measure of wound healing. Localised BIS resistance and phase angle triplicate measures, of minor limb burns, were collected on two serial occasions. Circumference limb measures were taken at the localised burn site to determine a truncated limb volume. Proportional-odds ordered logistic regression analyses determined resistance at zero frequency (R₀, indicative of edema) and resistance of total body fluid (R_inf) were significantly associated with healing after adjustment for the influence of surgery. A one unit increase in R₀ and R_inf increased the odds of wound healing by 6% and 5% respectively (p<0.01). Phase angle at 50kHz and R_i were not significantly associated with the markers of the wound healing process. Spearman's correlation determined there was a significant association between a healing wound and limb segment volume (ml) (rho -0.30, p<0.01). BIS is a technique, which has the potential to monitor the progress of wound healing.

Current concepts on burn wound conversion-A review of recent advances in understanding the secondary progressions of burns

Burn wound conversion describes the process by which superficial partial thickness burns convert into deeper burns necessitating surgical intervention. Fully understanding and thus controlling this phenomenon continues to defy burn surgeons. However, potentially guiding burn wound progression so as to obviate the need for surgery while still bringing about healing with limited scarring is the major unmet challenge. Comprehending the pathophysiologic background contributing to deeper progression of these burns is an essential prerequisite to planning any intervention. In this study, a review of articles examining burn wound progression over the last five years was conducted to analyze trends in recent burn progression research, determine changes in understanding of the pathogenesis of burn conversion, and subsequently examine the direction for future research in developing therapies. The majority of recent research focuses on applying therapies from other disease processes to common underlying pathogenic mechanisms in burn conversion. While ischemia, inflammation, and free oxygen radicals continue to demonstrate a critical role in secondary necrosis, novel mechanisms such as autophagy have also been shown to contribute affect significantly burn progression significantly. Further research will have to determine whether multiple mechanisms should be targeted when developing clinical therapies.

Evaluation of the effect of thymoquinone treatment on wound healing in a rat burn model

Thymoquinone (TQ) is a plant extract that has been shown to have antimicrobial, anti-inflammatory, and antioxidant effects. Because of these activities, the authors hypothesized that TQ would reduce inflammation and oxidative stress and accelerate wound closure in a rat model of deep second-degree burns. For the purposes of this study, 40 Sprague-Dawley rats were divided into five groups of eight rats each. Group 1 was the control group, group 2 was the silver sulfadiazine group, group 3 was treated with systemic TQ, group 4 received topical TQ, and group 5 was administered topical and systemic TQ. After the deep second-degree burn damage was created, daily dressing changes and TQ administration were continued in the study groups for a period of 21 days. Systemic TQ was administered intraperitoneally at a dose of 2 mg/kg/day, whereas the topical treatment was applied using a 0.5% solution. The changes in the wound site were observed macroscopically, histopathologically, microbiologically, and biochemically in all groups. The smallest necrotic areas were observed at the end of the study in the groups that were administered a combination of systemic and topical TQ, or solely topical TQ (6.1 ± 1.6 cm and 6.7 ± 0.4 cm, respectively), whereas the largest necrotic areas were observed in the control group (11.2 ± 1.2cm). The total antioxidant state levels in the control group were significantly lower than in the other groups (P < .05), whereas the total oxidative stress levels were lower in the TQ groups compared with the control group (P < .05). The lowest bacterial counts were observed in the groups treated with both topical and systemic TQ (P < .05). TQ given systemically and/or topically reduced inflammation and oxidative stress and accelerated the rate of wound closure or reepithelialization.

An effective antioxidant drug on prevention of the necrosis of zone of stasis: N-acetylcysteine

The zone of stasis, the encircling area of the zone of coagulation, is a critical area which determines the depth and width of the necrosis in burns. Many agents were proposed to salvage the zone of stasis. Due to the known preventive and therapeutic effects of N-acetylcysteine on hepatotoxicity, nephrotoxicity, pulmonary injury, and multiple organ failure in humans, the effect of N-acetylcysteine on saving the zone of stasis was investigated in this experimental study. The effects of N-acetylcysteine administration via oral or intraperitoneal route was compared in a rat comb-burn model. The extent of burn wounds was evaluated by photography and planimetry in the groups. Additionally, skin samples were obtained to analyze malondialdehyde levels to see the antioxidant effect of N-acetylcysteine. In control group (no treatment), the burn areas went to near total necrosis. In intraperitoneal and oral treatment groups, skin survival occurred in the interspace area of the comb. There was no difference between the groups in terms of MDA concentrations. In conclusion, this study showed us the possible saving effect of N-acetylcysteine on the zone of stasis. N-acetylcysteine may be used in the cases of severe burns, not only for its effects on wound healing but also the systemic effects of the drug.

Superabsorbent polymer-containing wound dressings have a beneficial effect on wound healing by reducing PMN elastase concentration and inhibiting microbial growth

A comprehensive in vitro approach was used to assess the effects of superabsorbent polymer (SAP) containing wound dressings in treatment of non-healing wounds. A slight negative effect on HaCaT cells was noted in vitro which is most likely due to the Ca(2+) deprivation of the medium by binding to the SAP. It could be shown that SAP wound dressings are able to bind considerable amounts of elastase reducing enzyme activity significantly. Furthermore, SAP's inhibit the formation of free radicals. The SAP-containing wound dressings tested also exhibited a significant to strong antimicrobial activity effectively impeding the growth of gram-negative and gram-positive bacteria as well as yeasts. In conclusion, in vitro data confirm the positive effect of SAP wound dressings observed in vivo and suggest that they should be specifically useful for wound cleansing.

Rapid recruitment and activation of macrophages by anti-Gal/α-Gal liposome interaction accelerates wound healing

Macrophages are pivotal in promoting wound healing. We hypothesized that topical application of liposomes with glycolipids that carry Galα1-3Galβ1-4GlcNAc-R epitopes (α-gal liposomes) on wounds may accelerate the healing process by rapid recruitment and activation of macrophages in wounds. Immune complexes of the natural anti-Gal Ab (constituting ∼1% of Ig in humans) bound to its ligand, the α-gal epitope on α-gal liposomes would induce local activation of complement and generation of complement chemotactic factors that rapidly recruit macrophages. Subsequent binding of the Fc portion of anti-Gal coating α-gal liposomes to FcγRs on recruited macrophages may activate macrophage genes encoding cytokines that mediate wound healing. We documented the efficacy of this treatment in α1,3galactosyltrasferase knockout mice. In contrast to wild-type mice, these knockout mice lack α-gal epitopes and can produce the anti-Gal Ab. The healing time of excisional skin wounds treated with α-gal liposomes in these mice is twice as fast as that of control wounds. Moreover, scar formation in α-gal liposome-treated wounds is much lower than in physiologic healing. Additional sonication of α-gal liposomes resulted in their conversion into submicroscopic α-gal nanoparticles. These α-gal nanoparticles diffused more efficiently in wounds and further increased the efficacy of the treatment, resulting in 95-100% regeneration of the epidermis in wounds within 6 d. The study suggests that α-gal liposome and α-gal nanoparticle treatment may enhance wound healing in the clinic because of the presence of high complement activity and high anti-Gal Ab titers in humans.

Immobilizing Cu,Zn-superoxide dismutase in hydrogels of carboxymethylcellulose improves its stability and wound healing properties

Hydrogels of carboxymethylcellulose (CMC) with 50 and 90% cross-linking degree (CMC50% and CMC90%, respectively) were prepared and loaded with bovine erythrocyte Cu,Zn-superoxide dismutase (SOD) to obtain two drug delivery systems: SOD-CMC50% and SOD-CMC90%. Resistance of native SOD to inactivation by H2O2 and the effect of applying SOD-CMC hydrogels to open wounds of rats' back skin were examined and compared to that of SOD trapped into CMC50% and CMC90% hydrogels. Also, the effect of CMC50% and SOD-CMC90% on human fibroblasts proliferation was evaluated at different times. It was found that SOD in the hydrogel was more resistant to H2O2 inactivation than the native enzyme and at the same time it reduced the time necessary for wound healing. Furthermore, the highest cell proliferation value was found for the CMC50% hydrogels, which had a three-dimensional structure suitable for gas and nutrient exchanges and improving cell life conditions.

Les formulations topiques à base d’enzymes

Research studies aimed at improving the enzyme catalytic efficiency and operational stability are considered as a recurrent challenge with topical enzyme-based formulations. A large number of plant and bacterial proteolytic enzymes have been studied as an early substitutive replacement for the mechanical debridement of partial-thickness burns. In addition, progress in protein engineering and vectorisation of drugs provide improvements in the approach of topical and photoprotective enzyme therapy.

Repetitive Ischemia–Reperfusion Injury: A Plausible Mechanism for Documented Clinical Burn-Depth Progression After Thermal Injury

Our previous studies confirmed the phenomenon of burn depth progression despite adequate Parkland formula resuscitation [Kim et al. J Burn Care Rehabil 2001;22960:406-6]. Repetitive ischemia-reperfusion injury (I-R) is a plausible explanation and is suggested by the concomitant swings we have observed in serum base deficit (BD) during resuscitation from burn shock. We chose to explore whether laser Doppler imaging (LDI) evidence of burn depth progression mirrored cycles of I-R (episodic swings in continuously measured BD). Positive findings would support the hypothesis that repetitive episodes of I-R is a factor in burn depth progression despite apparently adequate resuscitation. A total of 14 patients with severe life-threatening burns (median 51% TBSA) underwent continuous BD monitoring using a Paratrend 7 (Malvern PA) during 48 hours of resuscitation. Fluid needs were estimated using the Parkland formula, then were titrated to urine output. The slopes of BD changes were then analyzed. Worsening of BD greater than 0.2 mmol/l/min was noted, and a proportion derived relative to pooled data on 5-minute intervals. In four of the patients, LDI scans were performed on six representative areas sequentially every 4 hours. The analysis of median flux in these LDI images provided real-time determination of burn depth progression. Eight patients eventually died. Only four patients achieved a normal BD within 12 hours of monitoring despite exceeding the Parkland formula estimate and meeting urinary output parameters. Our analysis also showed cyclical peaks and valleys in the BD curve (P < .001), suggesting repetitive I-R insults. All increases in BD preceded changes that could be detected in vital signs or urine output. Finally, LDI confirmed that the burn depths continued to progress despite apparently adequate resuscitation, and also showed that there are similar peaks and valleys in the perfusion of the wounds (P < .0001), which mimic the changes in the BD curve. Responses to fluid resuscitation do not follow a linear pattern in the case of massive burns. These results in repetitive periods of tissue hypoperfusion evidenced by BD alterations and may contribute to progressive deepening of the burn wound.

GMP production of liposomes--a new industrial approach

A new scalable liposome production system is presented, which is based on the ethanol injection technique. The system permits liposome manufacture regardless of production scale, as scale is determined only by free disposable vessel volumes. Once the parameters are defined, an easy scale up can be performed by just changing the process vessels. These vessels are fully sterilizeable and all raw materials are transferred into the sanitized and sterilized system via 0.2 microm filters to guarantee an aseptic production. Liposome size can be controlled by the local lipid concentration at the injection point depending on process parameters like injection pressure, lipid concentration and injection rate. These defined process parameters are furthermore responsible for highly reproducible results with respect to vesicle diameters and encapsulation rates Compared to other technologies like the film method which is normally followed by size reduction through high pressure homogenization, ultrasonication or extrusion, no mechanical forces are needed to generate homogeneous and narrow distributed liposomes. Another important advantage of this method is the suitability for the entrapment of many different drug substances such as large hydrophilic proteins by passive encapsulation, small amphiphilic drugs by a one step remote loading technique or membrane association of antigens for vaccination approaches.

Effect of Polyvinylpyrrolidone-Iodine Liposomal Hydrogel on Wound Microcirculation in SKH1-hr Hairless Mice

AIM

Polyvinylpyrrolidone-iodine liposomal hydrogel (PVP-ILH) is a hydrogel formulation based on polyvinylpyrrolidone-iodine (PVP-I) and liposomes. The beneficial effects of PVP-ILH on wound healing have been previously shown. The aim of this study was to investigate the effects of topically applied PVP-ILH on wound microcirculation.

MATERIALS AND METHODS

Experiments were performed on wounds in male SKH1-hr hairless mice (n = 48). Mice were randomized into five treatment groups: mice treated with polyacrylic acid (PAA) and PAA 1:10 as well as PVP-ILH and PVP-ILH 1:10. Mice treated with sodium chloride served as control. Immediately as well as 3, 7, and 14 days after wounding, intravital fluorescent microscopy (IFM) was performed to determine wound surface area and standard microcirculatory parameters.

RESULTS

Topically administered PVP-ILH reduced wound size significantly faster compared to controls. Standard microcirculatory parameters, e.g. functional capillary density (FCD) and plasma leakage, showed no differences. FCD increases in all groups after wound creation. Using PVP-ILH, a trend towards higher FCD was observed.

CONCLUSION

The wound model in hairless mice in combination with IFM is suitable to qualitatively assess wound microcirculation over a period of 2 weeks even after topical application of pigmented ointments. PVP-ILH showed a positive effect on dermal wound healing and wound microcirculation.

Effect of Vacuum Assisted ClosureR Therapy on early systemic cytokine levels in a swine model

Vacuum Assisted Closure (V.A.C.) Therapy has previously been shown to facilitate healing of wounds. However, the physiological mechanism(s) of this treatment modality and its systemic effects require further investigations. The goal of this porcine study was to investigate the effect of V.A.C. Therapy on the systemic distribution of the inflammatory cytokines interleukin (IL)-6, IL-8, IL-10, and transforming growth factor-beta1. Twelve pigs were each given one full-thickness excisional wound, using electrocautery. Six of the pigs were treated with V.A.C. Therapy and six with saline-moistened gauze. Serum samples were collected immediately after wound creation, and hourly for 4 hours. Samples were analyzed using commercially available enzyme-linked immunosorbent assay kits. During the initial 4 hours of treatment, V.A.C. Therapy resulted in earlier and greater peaking of IL-10 and maintenance of IL-6 levels compared with saline-moistened gauze controls, which showed decreased IL-6 values over the first hour (both at p<0.05). No other treatment-based differences were detected.

Effect of low-level helium-neon laser therapy on the healing of third-degree burns in rats

This paper presents the results of a study on the effects of low-level helium-neon laser therapy (LL He-Ne LT) on the healing of burns. Seventy-eight adult male rats, having been subjected to third-degree burns, were randomly divided into four groups: two laser treated groups (n=20, each), one control group (n=19) and one nitrofurazone treated group (n=19). In the two laser treated groups, the burns were treated on a daily basis with LL He-Ne LT with an energy density of 1.2 and 2.4 J/cm(2), respectively. The response to treatment was assessed histologically at 7, 16 and 30 days after burning, and microbiologically at day 15. Analysis of variance showed that the mean of blood vessel sections in the 1.2J/cm(2) laser group was significantly higher than those in the other groups and the mean of the depth of new epidermis in the 2.4 J/cm(2) laser group on day 16 was significantly lower than in the nitrofurazone treated group (P=0.025, P=0.047, respectively). When Staphylococcus aureus and Pseudomonas aeruginosa grew in more than 50% of samples obtained from control group, there were no S. aureus and P. aeruginosa in the samples of 2.4 J/cm(2) laser group. It is concluded that LL He-Ne LT induced the destruction of S. aureus and P. aeruginosa in third-degree burns of rats, yet at the same time our histological findings showed that LL He-Ne LT caused a significant increase in the mean of blood vessel sections on day 7 after third degree burns and a decrease in the mean of the depth of new epidermis on day 16 after the same burns in rats.

Reactive oxygen species scavenging activity during periodontal mucoperiosteal healing: An experimental study in dogs

Excessive release of reactive oxygen species (ROS) in wounded tissue due to inflammation and ischaemia is a deleterious and destructive phenomenon for the healing process. Hence, scavenging of ROS is one of the essential steps in normal wound repair. In this study, we presented a profile of free radical scavenging enzyme (FRSE) activity of periodontal mucoperiosteal wounds in order to investigate ROS activity during periodontal wound healing. Mucoperiosteal periodontal flaps were elevated in the mandibular buccal region of seven dogs between the first premolar and first molar teeth, creating acute incisional wounds in the inner side of the flaps and they were replaced 30 min after elevation. Gingival samples taken from certain biopsy regions at baseline (before flap elevation), day 3, 12, 21 and 30 were processed for detection of active amounts of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX). All enzyme activities had increased by more than 100% of their baseline levels by day 3. SOD activity decreased gradually from days 3 to 30 and reached a level lower than the baseline value. The increase in CAT activity continued until day 21, and decreased to a level higher than the baseline value by day 30. GPX also decreased from day 3, and reached a level less than its baseline value by day 30. Our results suggest that FRSEs may contribute to the detoxification of ROS during periodontal mucoperiosteal healing. This relationship may be utilized to facilitate soft tissue and/or flap management in periodontal or intra-oral treatments.

Influence of selected wound dressings on PMN elastase in chronic wound fluid and their antioxidative potential in vitro

Exudates from non-healing wounds contain elevated levels of proteolytic enzymes, like elastase from polymorphonuclear granulocytes (PMN elastase), reactive oxygen species (ROS) and reactive nitrogen species (RNS). The overproduction of proteolytic enzymes leads to reduced concentrations of growth factors and proteinase inhibitors, resulting in an imbalance between degradation and remodelling processes. Thus, the reduction of protein-degrading enzymes and scavenging of ROS and RNS seem to be suitable ways to support the healing process of chronic stagnating wounds. The aim of this study was to test selected wound dressings from different biomaterials (collagen, oxidized regenerated cellulose (ORC) and ORC/collagen mixture), regarding their antioxidative potential in vitro and their influence on the concentration and activity of PMN elastase in chronic wound fluid. Antioxidant capacity of the investigated wound dressing was determined by a pholasin-based chemiluminescent assay. PMN elastase concentration was determined by means of ELISA. Enzyme activities could be measured by a fluorescence assay. As the presented data demonstrates, all tested materials showed antioxidant capacity. In addition, the investigated materials were able to reduce the concentration and activity of PMN elastase. Beside other aspects, such as biocompatibility, biodegradability, fluid absorption and clinical effects (e.g. angiogenesis and microcirculation), the understanding of these properties may help to support the further refinement of wound dressings for improved wound healing.

Leukotriene receptor blocker montelukast protects against burn-induced oxidative injury of the skin and remote organs

Thermal injury elicits several systemic consequences, among them the systemic inflammatory response where the generation of reactive oxygen radicals and lipid peroxidation play important roles. In the present study, we investigated whether the leukotriene receptor blocker montelukast is protective against burn-induced remote organ injury. Under brief ether anaesthesia, shaved dorsum of the rats was exposed to 90 degrees C (burn group) or 25 degrees C (control group) water bath for 10 s. Montelukast (10 mg/kg) or saline was administered intraperitoneally immediately after and at the 12th hour of the burn injury. Rats were decapitated 24 h after burn injury and the tissue samples from lung, liver, kidney and skin were taken for the determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and collagen contents. Tissues were also examined microscopically. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels and creatinine, urea (BUN) concentrations were determined to assess liver and kidney function, respectively. Tumor necrosis factor-alpha (TNF-alpha) and lactate dehydrogenase (LDH) were also assayed in serum samples. Severe skin scald injury (30% of total body surface area) caused a significant decrease in GSH level, which was accompanied with significant increases in MDA level, MPO activity and collagen content of tissues. Similarly, serum ALT, AST and BUN levels, as well as LDH and TNF-alpha, were elevated in the burn group as compared to control group. On the other hand, montelukast treatment reversed all these biochemical indices, as well as histopathological alterations, which were induced by thermal trauma. Findings of the present study suggest that montelukast possesses an anti-inflammatory effect on burn-induced damage in remote organs and protects against oxidative organ damage by a neutrophil-dependent mechanism.

Effect of low-level laser therapy on the healing of second-degree burns in rats: a histological and microbiological study

This paper presents the results of a study on the effects of two different doses of low-level laser therapy on healing of deep second-degree burns. Sixty rats were randomly allocated to one of four groups. A deep second-degree burn was inflicted in each rat. In the control group burns remained untreated; in two laser treated groups the burns were irradiated daily with low-level helium-neon laser with energy densities of 1.2 and 2.4 J/cm2, respectively. In the fourth group the burns were treated topically with 0.2% nitrofurazone cream every day. The response to treatments was assessed histologically at 7, 16 and 30 days after burning, and microbiologically at Day 15. The number of macrophages at day 16, and the depth of new epidermis at day 30, was significantly less in the laser treated groups in comparison with control and nitrofurazone treated groups (P=0.000). Staphylococcus epidermidis was found in the 70% of rat wounds in the laser treated groups in comparison with 100% of rats in the control group. S. aureus was found in the 40% rat wounds in the nitrofurazone treated group, but there was not found in the wounds of laser treated, and control groups. It is concluded that low-level laser therapy of deep second-degree burn caused significant decrease in the number of macrophage and depth of new epidermis. In addition, it decreased incidence of S. epidermidis and S. aureus.

Burn-induced oxidative injury of the gut is ameliorated by the leukotriene receptor blocker montelukast

There is increasing evidence that oxidative stress has an important role in the development of multiorgan failure after major burn injury. In the present study, we investigated whether the leukotriene receptor blocker montelukast is protective against burn-induced injury of the gut. Under brief ether anaesthesia, shaved dorsum of the rats was exposed to 90 degrees C (burn group) or 25 degrees C (control group) water bath for 10 s. Montelukast (10 mg/kg) or saline was administered intraperitoneally immediately after and at the 12th hour of the burn injury. Rats were decapitated 24 h after burn injury and the skin samples, as well as tissue samples from stomach, ileum and colon, were taken for the determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and collagen contents. Tissues were also examined microscopically. Tumor necrosis factor-alpha (TNF-alpha) and lactate dehydrogenase (LDH) were assayed in serum samples. Severe skin scald injury (30% of total body surface area) caused a significant decrease in GSH level, which was accompanied with significant increases in MDA level, MPO activity and collagen content of tissues. Similarly, serum TNF-alpha and LDH were elevated in the burn group as compared to control group. On the other hand, montelukast treatment reversed all these biochemical indices, as well as histopathological alterations, which were induced by thermal trauma. Findings of the present study suggest that montelukast possesses an anti-inflammatory effect on burn-induced gastrointestinal damage and protects against oxidative injury by a neutrophil-dependent mechanism.

Rat models of skin wound healing: a review

Rats have been widely used in the study of skin wound healing and the efficacy of different treatment modalities. This particular animal species is often selected for its availability, low cost, and small size. To define the current use of rat skin wound healing models, this manuscript provides a review of articles published between 2000 and 2003 that chose rats as their research animals. Of the 55 articles reviewed, it was found that 38.2% of the studies used incisional models and 38.2% used excisional models, with some studies using combinations. The majority of the studies (78.2%) used the rat's dorsum as the wound location. Male Sprague Dawley in the 250-300 gram weight range were the most preferred rats. Sodium pentobarbital/pentobarbitone was the most commonly used anesthetic choice. Similarities and differences in the selected experimental conditions are noted and questions are raised with regard to comparability between studies and the ability to transfer the data from the animal model to the human clinical situation. Attempts to compare studies for the advancement of wound healing knowledge are being hampered by the differences found between the studies. Standardization in reporting could facilitate comparisons and may instigate additional research that favors the inevitable comparisons between the studies. Thus, universal reporting requirements need to be developed for animal wound healing studies.