Progressive tissue injury in burns is reduced by rNAPc2

Intradermal methylene blue administration on the progression of burn injuries

OBJECTIVE

A burn injury has two defined areas: central necrosis and an adjacent area of ischaemia, which may or may not progress to necrosis. The concentration of nitric oxide (NO) increases after burn injury and may originate from potent oxidising agents. Methylene blue (MB) may act as an antioxidant and is supposed to reduce burn progression. This investigation was carried out to evaluate the effects of intradermal MB on necrosis progression in burns.

METHODS

Full-thickness burn injuries were performed by applying a heated metal comb on the shaved back of male Wistar rats. The animals were divided into three groups: Control (C, n=7); MB (2mg/kg) one hour after burn injury (MB1h, n=11); and MB (2mg/kg) six hours after burn injury (MB6h, n=8). After seven days the lesions were photographed for visual assessment of burn necrosis; full-thickness cuts of lesions were dyed with Masson and Giemsa for microscopic histopathology; and tissue fragments of unburned interspaces were processed for chemiluminescence with nitrite/nitrate (NOX) and malondialdehyde (MDA) as oxidative stress markers.

RESULTS

No statistically significant differences between groups were observed during visual analysis and NOX dosage. However, in microscopic analysis, the MB1h and MB6h groups showed smaller areas of necrosis, less inflammatory infiltration, and a more significant extension of interspaces. Furthermore, the dosage of MDA revealed that the MB1h group showed lower values when compared with the control group (p=0.001).

CONCLUSIONS

The study provided good evidence that MB intradermal injection can reduce necrosis progression in ischaemic perilesional areas and suggests an alternative to treating burns.

Histological Studies on a Newly Isolated Bacillus subtilis D10 Protease in the Debridement of Burn Wound Eschars Using Mouse Model

Background: Proteases are among the most important industrial enzymes, playing a critical role in the physiological, biochemical, and regulatory processes of all living organisms. This study evaluated the histological effects of a Bacillus subtilis D10 protease in combination with the antibacterial ointment silver sulfadiazine (SSD) on the burned skin of mice. Materials and Methods: The bacterial proteolytic enzyme was produced and purified through DEAE-Sepharose CL-6B and Sephadex G-100 FF. The in vitro protease specificity was then determined. The dorsal skin of albino mice was burned with 80% HCl solution, then treated under three conditions: cold cream, SSD, and SSD combined with the tested protease. After 15 days of daily treatment, the mice were sacrificed and skin tissue samples were histopathologically examined using hematoxylin eosin, and Masson trichrome staining. Results: The D10 protease hydrolyzed the proteinaceous components of eschars (fibrin, normal collagen, and denatured collagen) in vitro. Mice skins treated with protease and SSD mixture showed promising results, with more rapid healing than the other treatments. This group regenerated epidermis and dermis with newly formed granulated follicles, fibroblasts and blood capillaries in the dermis, and collagen fibers in the hypodermis. Conclusions: These results suggest that the serine protease produced by B. subtilis D10 promotes wound healing of mice skin burnt with HCl and restores the normal architectural pattern in a shorter time than the standard treatments.

Effects of Carnosine, Ankaferd, and Silver Sulfadiazine on an Experimental Burn Model: Roles of Irisin and HSP70

In this study, the effects of carnosine, ankaferd, and 1% silver sulfadiazine applied topically on second-degree burns were investigated and the roles of irisin and Heat shock protein 70 (HSP70) in this healing process were evaluated. Ninety male albino rats were used and divided into five groups. The groups were classified as control, burn, burn + carnosine (CAR), burn + ankaferd (ABS), and burn + silver sulfadiazine (SS). It was found that level of irisin increased in the first week and decreased in the second week in the burn and CAR groups. In the ABS and SS groups, the level of irisin was determined that started to increase in the first week and continued to increase in the second week. The level of HSP70 was found to increased in the first week in burn and CAR groups and decreased in the second week, but started to increase in the second week in ABS and SS groups. Both levels of irisin and HSP70 were observed to decreased in all treatment groups in the third week. In this study, it was shown that ankaferd and silver sülfadiazine treatments cause an increase in the irisin levels in the early period and a gradually increase in HSP70 levels in the later period in burns. The inflammatory response was observed to be limited in the early period in the ankaferd and sulfadiazin groups. It was concluded that these findings were effective in early wound healing in burns.

Role of autophagy and apoptosis in wound tissue of deep second-degree burn in rats

OBJECTIVES

The pathogenesis of burn wound progression is poorly understood. Contributing factors include continuous loss of blood perfusion, excessive inflammation, and elevated apoptosis levels in wound tissue. Macroautophagy (here referred to simply as "autophagy") is associated with many chronic diseases. The authors hypothesized that autophagy is involved in burn wound progression in a rat model of deep second-degree burn.

METHODS

Deep second-degree burns were modeled using a brass rod heated to 100°C applied for 6 seconds to the back skin of Wistar rats. Full-thickness biopsies were obtained from burned and nonburned controls at several times postburn. Western blotting and immunohistochemical (IHC) staining determined expression of the autophagy markers Light Chain 3 (LC3) and beclin-1. Apoptosis was determined by terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) assay and laser Doppler flowmetry (LDF)-measured tissue perfusion. Myeloperoxidase (MPO) activity assay measured inflammation. Hematoxylin and eosin (H&E) and Masson's trichrome staining-determined pathology and wound depth.

RESULTS

The LC3 and beclin-1 protein level in burn wounds decreased to one-fourth of normal levels (p<0.01) over 24 hours and then began to increase but still did not reach their normal level. TUNEL-positive cells in burn wounds were 3.7-fold (p<0.01) elevated over 48 hours and then decreased slightly, yet still remained higher than in normal skin. The burn wound progressed in depth over 72 hours. In addition, significant decrease in LDF values and upregulation of MPO activity were observed. Enhanced LC3-positive cells were observed in the deep dermal layer of burn wounds as shown by IHC staining.

CONCLUSIONS

A reduction in autophagy and blood flow and an increase in apoptosis and inflammation were observed in burn wounds early during the course of burn injury progression. This suggests that autophagy, complemented by apoptosis, play important roles in burn progression. Enhanced autophagy in the deep dermis may be a prosurvival mechanism against ischemia and inflammation after burn injury.

The effect of subcutaneous mesenchymal stem cell injection on statis zone and apoptosis in an experimental burn model

BACKGROUND

In an acute burn injury the zone of stasis is initially vital but may progress to coagulation necrosis with time. In this study, salvage of the zone of stasis was aimed at by subcutaneous mesenchymal stem cell injection.

METHODS

Mesenchymal stem cells were obtained from the bone marrow of Sprague-Dawley rats (n = 10). Twenty Sprague-Dawley rats received thermal injury on the back according to the previously described "comb burn" model. Thirty minutes after the burn injury, mesenchymal stem cells were injected subcutaneously to the stasis zone of the experimental group (n = 10). Animals in the control group (n = 10) were given the same amount of saline without mesenchymal stem cells. Animals in the sham group (n = 6) did not receive any thermal trauma. Seventy-two hours after the burn injury, scintigraphic examination was applied to determine average vital tissue at the stasis zone. Thereafter, skin samples were assessed by immunohistochemistry assay for apoptosis count. The blood samples drawn before and 72 hours after the burn injury were analyzed to determine systemic cytokine levels.

RESULTS

The apoptosis count of the control group was found to be significantly higher than that of the experimental group. Vital tissue percentage of the stasis zone was significantly higher for the experimental group than for the control group. The cytokine levels did not reveal any statistically significant difference between the groups.

CONCLUSION

Apoptosis count and scintigraphic results of this study confirm that mesenchymal stem cell treatment has a statistically significant benefit for the survival of the stasis zone in acute burn.

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.

Erythropoietin in the prevention of experimental burn progression

Background

Damage control is essential in first aid of burn lesions. The aim of the present study was to investigate whether systemic erythropoietin (EPO) administration could prevent secondary burn progression in an experimental model.

Methods

The burn comb model creates four rectangular burn surfaces intercalated by three unburned zones prone to progression. Twenty-one Wistar rats were randomized to a control group or to receive intraperitoneal EPO (500 units per kg) once a day for 5 days starting 45 min (EPO45min) or 6 h (EPO6h) after burn injury. Histological analyses assessing burn depth, inflammation and neoangiogenesis, planimetric evaluation of burn progression, and laser Doppler flowmetry to assess perfusion were performed after 1, 4 and 7 days. Final scarring time and contracture rate were assessed once a week.

Results

Burn progression was decreased significantly with EPO45min but not EPO6h; progression of burn depth stopped in the intermediate dermis (mean(s.e.m.) burn depth score 3·3(0·6) for EPO45min versus 4·7(0·3) and 5·0(0·0) for EPO6h and control respectively on day 7; P = 0·026) and the surface extension was significantly reduced (45(8), 65(4) and 78(4) respectively on day 7; P = 0·017). This was paralleled by faster re-establishment of perfusion with EPO45min (114(5) per cent on day 4 versus 85(6) and 91(3) per cent for EPO6h and control respectively; P = 0·096). The reduction in progression resulted in a decreased healing time (7·3(0·7) weeks for EPO45min versus 11·5(1·0) and 10·8(0·5) weeks for EPO6h and control; P = 0·020) and contracture rate (P = 0·024).

Conclusion

Early EPO prevented burn progression, mainly by improved vascular perfusion.

Local and systemic treatments for acute edema after burn injury: a systematic review of the literature

Burn injury is a complex trauma that results in local and generalized edema. Edema fluid limits the exchange of vital nutrients in healing the burn wound and will compromise vulnerable tissues. Although the importance of edema control in tissue salvage is recognized, treatments targeted at edema control have not been critically reviewed. Thus, the objective was to assess the evidence for the effectiveness of local and systemic treatments for edema management immediately after burn injury. Searches for randomized controlled trials were conducted of online databases, research and thesis registers, and grey literature repositories. Handsearches included journals, bibliographies, and proceedings. Authors were contacted to clarify and submit extra study details. Eight studies were included. Management of acute major burn resuscitation including colloid increases lung edema (mean difference [MD], 0.04 ml/ml alv vol; 95% confidence interval [CI], 0.03-0.04; P < .00001) and mortality (risk ratio, 3.67; 95% CI, 1.16-11.58; P = .03). Continuous administration of vitamin C in acute burn resuscitation reduces local wound edema (MD, -3.50 ml/g; 95% CI, -4.63 to -2.37; P < .00001) and systemic fluid retention (MD, -8.60 kg; 95% CI, -13.47 to -3.73; P = .0005). Local acute hand burn edema is reduced (MD, -29.00 ml; 95% CI, -53.14 to -4.86; P = .02), and active hand motion increased (MD, 10.00°; 95% CI, 4.58-15.42; P = .0003), using electrical stimulation with usual physiotherapy. Each review outcome was based on a small single-facility study. Thus, future research in intervention for acute burn edema must focus on multicentre trials and validation of outcome measures in the burn population.

Saving the zone of stasis in burns with activated protein C: an experimental study in rats

Salvage of the zone of stasis is a major subject of focus in burn research. Use of various antithrombotic, anti-inflammatory and antioxidant drugs have been studied experimentally, with reports of favourable results; however, none became popular in clinical practice. Activated protein C (APC) is a well-known physiologic anticoagulant. Recent studies revealed that APC contributes not only to systemic anticoagulant activities but also to anti-inflammatory activities by inhibiting leucocyte activation associated with TNF production. The likely favourable effects of APC on salvage of the zone of stasis were investigated on a well-described experimental rat burn model representing the zone of stasis according to the 'burn comb model'. Twenty Sprague-Dawley rats were used and randomly separated into experimental and control groups. Two hours after inducing injury, 100 microg kg(-1) APC (Sigma, Boehringer Ingelheim, Germany) was administered to the experimental group through the caudal vein while 0.9% saline was injected through the same route in the control group. Laser Doppler flowmetry measurements and autoradiography were used for evaluation of perfusion and viability in the zone of stasis. At day 3, the differences between the results obtained from the treatment and the control groups were found to be statistically significant (p<0.05). Our experimental study revealed that APC improved tissue perfusion and decreased the area of skin necrosis in the zone of stasis in rats. The dual effect of APC, each of which has been shown to be favourable in saving the zone of stasis, may make this agent effective with a single effect in treatment of burn injury.

Helminth infections: the great neglected tropical diseases

Helminths are parasitic worms. They are the most common infectious agents of humans in developing countries and produce a global burden of disease that exceeds better-known conditions, including malaria and tuberculosis. As we discuss here, new insights into fundamental helminth biology are accumulating through newly completed genome projects and the nascent application of transgenesis and RNA interference technologies. At the same time, our understanding of the dynamics of the transmission of helminths and the mechanisms of the Th2-type immune responses that are induced by infection with these parasitic worms has increased markedly. Ultimately, these advances in molecular and medical helminth biology should one day translate into a new and robust pipeline of drugs, diagnostics, and vaccines for targeting parasitic worms that infect humans.

The canine hookworm genome: analysis and classification of Ancylostoma caninum survey sequences

Hookworms infect nearly a billion people. The Ancylostoma caninum hookworm of canids is a model for studying human infections and information from its genome coupled with functional genomics and proteomics can accelerate progress towards hookworm control. As a step towards a full-scale A. caninum genome project, we generated 104,000 genome survey sequences (GSSs) and determined the genome size of the canine hookworm. GSSs assembled into 57.6 Mb of unique sequence from a genome that we estimate by flow cytometry of isolated nuclei to be 347 +/- 1.2 Mb, substantially larger than other Rhabditina species. Gene finding identified 5538 genes in the GSS assembly, for a total of 9113 non-redundant A. caninum genes when EST sequences are also considered. Functional classifications of many of the 70% of genes with homology to genes in other species are provided based on gene ontology and KEGG associations and secreted and membrane-bound proteins are also identified.