Morphological parameters for assessment of burn severity in an acute burn injury rat model

Aesthetic Treatment of Acute Burns of the Face Using Electro-Photobiomodulation

The quicker a second-degree burn wound heals, the less surgery is required. Low-energy laser therapy may expedite the healing of wounds, according to recent literature findings. To establish this, it was decided to carry out a clinical trial on acute burn patients to demonstrate whether electro-photobiomodulation (EPBM) therapy can hasten wound closure, thereby obviating the need for surgery without worsening hypertrophic scarring and contracture. In clinical prospective analysis, 42 acute burn patients with recent burns to the face alone (13) or the face and additional areas (29). Twenty-six males and 16 women were included. All patients received twice-weekly sessions of intense pulsed light (IPL) and radiofrequency for the face and other areas. Clinical assessment showed excellent results in 34 (81%) patients, good results in 6 (14.3%) patients, fair results in two (4.7%) patients, and no poor results were reported. The results of this clinical trial showed that IPL and radiofrequency therapy can rapidly heal deep skin burns without the need for surgery. and lowered the incidence of hypertrophic scarring and contractures. EPBM induces better aesthetic and functional outcomes (particularly in burns of the face).

Triage of in vivo burn injuries and prediction of wound healing outcome using neural networks and modeling of the terahertz permittivity based on the double Debye dielectric parameters

The initial assessment of the depth of a burn injury during triage forms the basis for determination of the course of the clinical treatment plan. However, severe skin burns are highly dynamic and hard to predict. This results in a low accuracy rate of about 60 - 75% in the diagnosis of partial-thickness burns in the acute post-burn period. Terahertz time-domain spectroscopy (THz-TDS) has demonstrated a significant potential for non-invasive and timely estimation of the burn severity. Here, we describe a methodology for the measurement and numerical modeling of the dielectric permittivity of the in vivo porcine skin burns. We use the double Debye dielectric relaxation theory to model the permittivity of the burned tissue. We further investigate the origins of dielectric contrast between the burns of various severity, as determined histologically based on the percentage of the burned dermis, using the empirical Debye parameters. We demonstrate that the five parameters of the double Debye model can form an artificial neural network classification algorithm capable of automatic diagnosis of the severity of the burn injuries, and predicting its ultimate wound healing outcome by forecasting its re-epithelialization status in 28 days. Our results demonstrate that the Debye dielectric parameters provide a physics-based approach for the extraction of the biomedical diagnostic markers from the broadband THz pulses. This method can significantly boost dimensionality reduction of THz training data in artificial intelligence models and streamline machine learning algorithms.

Efficacy of stromal vascular fraction and enzyme-free mechanical isolation therapy in experimental full thickness burn wounds

BACKGROUND

Autologous cell suspensions obtained by a stromal vascular fraction (SVF) and enzyme-free mechanical isolation (EMI) are an alternative in the treatment of burn wounds. In this study, we aimed to investigate the effect of autologous cell suspensions obtained by SVF and EMI on full-thickness skin burn wounds.

METHODS

A total of 45 male Sprague-Dawley rats were divided into three groups, SVF group, EMI group, and SVF + EMI group. The groups were also classified as the first, second, and third week of the burn to reveal the effect of the treatment on the burn in the early, middle, and late stages. For treatment, 0.2 ml SVF or 0.2 ml EMI was injected subcutaneously into the burn lesions of the subjects. Histopathological examination was performed on the burn wounds taken at the end of the experiment, and Ki67, CD44, CD73, CD90, and CK17 expressions were evaluated.

RESULTS

Histological examination revealed that there was no improvement in the control samples, but the skin was multicellular, vascularization was present. Histologic scores in all groups was significantly better than control, and SVF + EMI was the best group in terms of recovery (p < 0.05). Ki67, CK17, CD44, CD73, and CD90 expressions were significantly higher in the treatment groups compared to the control (p < 0.05).

CONCLUSION

We found in our study that both applications significantly increased the healing of the burn wound. Moreover, SVF + EMI application provided more improvement than SVF or EMI alone.

Measuring collagen injury depth for burn severity determination using polarization sensitive optical coherence tomography

Determining the optimal treatment course for a dermatologic burn wound requires knowledge of the wound’s severity, as quantified by the depth of thermal damage. In current clinical practice, burn depth is inferred based exclusively on superficial visual assessment, a method which is subject to substantial error rates in the classification of partial thickness (second degree) burns. Here, we present methods for direct, quantitative determination of the depth extent of injury to the dermal collagen matrix using polarization-sensitive optical coherence tomography (PS-OCT). By visualizing the depth-dependence of the degree of polarization of light in the tissue, rather than cumulative retardation, we enable direct and volumetric assessment of local collagen status. We further augment our PS-OCT measurements by visualizing adnexal structures such as hair follicles to relay overall dermal viability in the wounded region. Our methods, which we have validated ex vivo with matched histology, offer an information-rich tool for precise interrogation of burn wound severity and healing potential in both research and clinical settings.

A modified burn comb model with a new dorsal frame that allows for local treatment in partial-thickness burns in rats

Burn wound progression (BWP) leads to vertical and horizontal injury extension. The "burn comb model" is commonly used, in which a full-thickness burn with intercalated unburned interspaces is induced. We aimed to establish an injury progressing to the intermediate dermis, allowing repeated wound evaluation. Furthermore, we present a new dorsal frame that enables topical drug application. 8 burn field and 6 interspaces were induced on each of 17 rats' dorsa with a 10-second burn comb application. A developed 8-panel aluminum frame was sutured onto 12 animals and combined with an Elizabethan collar. Over 14 days, macroscopic & histologic wound assessment and Laser-Speckle-Contrast-Imaging (LSCI) were performed besides evaluation of frame durability. The 10-second group was compared to 9 animals injured with a full-thickness 60-second model. Frame durability was sufficient up to day 4 with 8 of 12 frames (67%) still mounted. The 60-second burn led to an increased extent of interspace necrosis (p=0.002). The extent of necrosis increased between days 1 and 2 (p=0.001), following the 10-second burn (24%±SEM 8% to 40%±SEM 6%) and the 60-second burn (57%±SEM 6% to 76%±SEM 4%). Interspace LSCI perfusion was higher than burn field perfusion. It earlier reached baseline levels in the 10-second group (on day 1: 142%±SEM 9% vs. 60%±SEM 5%; p<0.001). Within day 1, the 10-second burn showed histological progression to the intermediate dermis, both in interspaces and burn fields. This burn comb model with its newly developed fixed dorsal frame allows investigation of topical agents to treat BWP in partial-thickness burns.

Experimental models for controlled burn injuries in rats: a systematic analysis of original methods and burn devices

AIM

Despite a wide variety of models found in literature, choosing the right one can be difficult as many of them are lacking precise methodology. This study aims to analyze and compare original burn models in terms of burn device and technique, parameters, and wound depth assessment.

METHODS

A systematic search was performed according to PRISMA guidelines on studies describing original experimental burn models in rats. The adapted PICO formula and ARRIVE checklist were followed for inclusion and assessment of quality of studies. Characteristics of animals, burn technique, burn parameters and method of histological confirmation of burn depth were recorded.

RESULTS

Twenty-seven studies were included in the final analysis. Most studies used direct contact with skin for burn infliction (n=20). The rat's dorsum was the most common site (n=18). Ten studies used manually controlled burn devices, while ten designed automatic burn devices with control over temperature (n=10), exposure time (n=5), and pressure (n=5). Most studies (n=7) used a single biopsy taken from the center of the wound to confirm burn depth immediately after burn infliction.

CONCLUSION

From the wide variety of burn models in current literature, our study provides an overview of the most relevant experimental burn models in rats aiding researchers to understand what needs to be addressed when designing their burn protocol. Models cannot be compared as burn parameters variate significantly. Assessment of burn depth should be done in a standardized, sequential fashion in future burn studies to increase reproducibility.

A Quantitative Assessment of Wound Healing With Oxygenated Micro/Nanobubbles in a Preclinical Burn Model

BACKGROUND

Burns are devastating injuries, carry significant morbidity, and require long-term treatment or multiple reconstructive procedures. Wound healing and secondary insults caused by burn wound conversion are amendable to therapeutic intervention, where ischemia has been cited as one of the major factors (Dermatol Surg. 2008;34:1159-1169). Halting injury progression in the zone of stasis is crucial as conversion creates increased burn surface area and depth, leading to local and systemic consequences (J Burns Wounds. 2006;5:e2). Oxygen-carrying micro/nanobubbles, MNB(O2), offer a novel technology that can be used to effectively deliver oxygen to burn wounds and potentially counteract burn wound ischemia.

METHODS

Topical irrigation with MNB(O2) of full-thickness burn wounds on a rodent model (n = 3) was compared against saline-treated controls (n = 3). Tissue structure (reduced scattering coefficient, μs'), oxyhemoglobin concentration (cHbO2), and tissue perfusion were quantified over the course of 28 days through spatial frequency domain imaging and laser speckle imaging. Histological samples taken at the end of the experiment were examined for evidence of wound healing.

RESULTS

Findings in this preliminary study showed hastened healing with significant differences in spatial frequency domain imaging-measured μs' during wound healing (days 11-28) in MNB(O2) group. The healing "tipping point" seemed to occur at days 9 to 11 with increased collagen organization and increased cHbO2 occurring around that period confirming the gross healing improvements observed. In addition, histological evidence indicated that only the MNB(O2) burns had reached the remodeling phase by the end of 28-day study period.

CONCLUSIONS

These preliminary findings propose the potential of MNB(O2) as a topical method for improving burn wound healing.

A Pilot Study of Negative Pressure Therapy with Autologous Skin Cell Suspensions in a Porcine Model

BACKGROUND

Negative pressure wound therapy (NPWT) is an option for securing meshed split thickness skin grafts (mSTSGs) after burn excision to optimize skin graft adherence. Recently, the use of autologous skin cell suspension (ASCS) has been approved for use in the treatment of burn injuries in conjunction with mSTSGs.To date, limited data exists regarding the impact of NPWT on healing outcomes when the cellular suspension is utilized. It was hypothesized that NPWT would not negatively impact wound healing of ASCS+mSTSG.

MATERIALS AND METHODS

A burn, excision, mSTSG, ASCS ± NPWT model was used. Two Duroc pigs were utilized in this experiment, each with 2 sets of paired burns. Four wounds received mSTSG+ASCS+NPWT through post-operative day 3, and 4 wounds received mSTSG+ACSC+ traditional ASCS dressings. Cellular viability was characterized prior to spraying. Percent re-epithelialization, graft-adherence, pigmentation, elasticity, and blood perfusion and blood vessel density were assessed at multiple time points through 2 weeks.

RESULTS

All wounds healed within 14 days with minimal scar pathology and no significant differences in percent re-epithelialization between NPWT, and non-NPWT wounds were observed. Additionally, no differences were detected for pigmentation, perfusion, or blood vessel density. NPWT treated wounds had less graft loss and improved elasticity, with elasticity being statistically different.

CONCLUSIONS

These data suggest the positive attributes of the cellular suspension delivered are retained following the application of negative pressure. Re-epithelialization, revascularization, and repigmentation are not adversely impacted. The use of NPWT may be considered as an option when using ASCS with mSTSGs for the treatment of full-thickness burns.

Gastric ablation as a novel technique for modulating electrical conduction in the in vivo stomach

Gastric motility is coordinated by underlying bioelectrical "slow wave" activity. Slow wave dysrhythmias are associated with motility disorders, including gastroparesis, offering an underexplored potential therapeutic target. Although ablation is widely used to treat cardiac arrhythmias, this approach has not yet been trialed for gastric electrical abnormalities. We hypothesized that ablation can create localized conduction blocks and modulate slow wave activation. Radiofrequency ablation was performed on the porcine serosa in vivo, encompassing a range of parameters (55-85°C, adjacent points forming a line, 5-10 s/point). High-resolution electrical mapping (16 × 16 electrodes; 6 × 6 cm) was applied to define baseline and acute postablation activation patterns. Tissue damage was evaluated by hematoxylin and eosin and c-Kit stains. Results demonstrated that RF ablation successfully induced complete conduction block and a full thickness lesion in the muscle layer at energy doses of 65-75°C for 5-10 s/point. Gastric ablation may hold therapeutic potential for gastric electrical abnormalities in the future.NEW & NOTEWORTHY This study presents gastric ablation as a new method for modulating slow wave activation and propagation in vivo, by creating localized electrical conduction blocks in the stomach, validated by high-resolution electrical mapping and histological tissue analysis. The results define the effective energy dose range for creating conduction blocks, while maintaining the mucosal and submucosal integrity, and demonstrate the electrophysiological effects of ablation. In future, gastric ablation can now be translated toward disrupting dysrhythmic slow wave activation.

Coming to Consensus: What Defines Deep Partial Thickness Burn Injuries in Porcine Models?

Deep partial thickness burns are clinically prevalent and difficult to diagnose. In order to develop methods to assess burn depth and therapies to treat deep partial thickness burns, reliable, accurate animal models are needed. The variety of animal models in the literature and the lack of precise details reported for the experimental procedures make comparison of research between investigators challenging and ultimately affect translation to patients. They sought to compare deep partial thickness porcine burn models from five well-established laboratories. In doing so, they uncovered a lack of consistency in approaches to the evaluation of burn injury depth that was present within and among various models. They then used an iterative process to develop a scoring rubric with an educational component to facilitate burn injury depth evaluation that improved reliability of the scoring. Using the developed rubric to re-score the five burn models, they found that all models created a deep partial thickness injury and that agreement about specific characteristics identified on histological staining was improved. Finally, they present consensus statements on the evaluation and interpretation of the microanatomy of deep partial thickness burns in pigs.

Indocyanine green dye angiography as an adjunct to assess indeterminate burn wounds: A prospective, multicentered, triple-blinded study

Supplemental digital content is available in the text.

BACKGROUND

Clinical assessment of indeterminate burn wounds has been reported to yield poor accuracy, even when performed by burn experts. Indocyanine green (ICG) dye angiography has been found to be highly accurate in assessing burn depth, but there is still limited evidence of its use in indeterminate burn wounds. This study aims to compare the accuracy of ICG angiography to that of clinical assessment in assessing indeterminate burn wounds.

METHODS

This is a prospective, multicentered, triple-blinded, experimental study. Participants were stable patients, admitted to the hospital with burn wounds of indeterminate depth. The burn wounds were clinically assessed by an attending plastic surgeon. ICG angiography was performed and evaluated by another surgeon. Tissue biopsies were obtained and sent for histological study to be assessed as the gold standard.

RESULTS

In the 30 burn sites that were assessed, the accuracy of ICG angiography was 100.0%, compared with 50.0% for clinical assessment (p < 0.001). Clinical assessment yielded a sensitivity of 33.3% and specificity of 66.7%, while ICG angiography yielded both a sensitivity and specificity of 100.0%. Therefore, the number needed to treat for using ICG angiography in indeterminate burn wounds was two.

CONCLUSION

Indocyanine green angiography yields a significantly higher accuracy than clinical assessment in indeterminate burn wounds. This intervention can, thus, be a useful tool to aid clinical judgment.

TRIAL REGISTRATION

Thai Clinical Trials Registry, number TCTR20170821001.

LEVEL OF EVIDENCE

Diagnostic test, level I.

Short-wave infrared light imaging measures tissue moisture and distinguishes superficial from deep burns

Existing clinical approaches and tools to measure burn tissue destruction are limited resulting in misdiagnosis of injury depth in over 40% of cases. Thus, our objective in this study was to characterize the ability of short-wave infrared (SWIR) imaging to detect moisture levels as a surrogate for tissue viability with resolution to differentiate between burns of various depths. To accomplish our aim, we constructed an imaging system consisting of a broad-band Tungsten light source; 1,200-, 1,650-, 1,940-, and 2,250-nm wavelength filters; and a specialized SWIR camera. We initially used agar slabs to provide a baseline spectrum for SWIR light imaging and demonstrated the differential absorbance at the multiple wavelengths, with 1,940 nm being the highest absorbed wavelength. These spectral bands were then demonstrated to detect levels of moisture in inorganic and in vivo mice models. The multiwavelength SWIR imaging approach was used to diagnose depth of burns using an in vivo porcine burn model. Healthy and injured skin regions were imaged 72 hours after short (20 seconds) and long (60 seconds) burn application, and biopsies were extracted from those regions for histologic analysis. Burn depth analysis based on collagen coagulation histology confirmed the formation of superficial and deep burns. SWIR multispectral reflectance imaging showed enhanced intensity levels in long burned regions, which correlated with histology and distinguished between superficial and deep burns. This SWIR imaging method represents a novel, real-time method to objectively distinguishing superficial from deep burns.

Experimental models of scald burns. A scope review

Purpose:

To conduct a scope review of the experimental model described by Walker and Mason, by identifying and analyzing the details of the method.

Methods:

The authors searched Pubmed-Medline, Cochrane-Bireme and PEDro databases for articles published between January 2016 and December 2018, using the following search queries: burns, burn injuries, models animal, and animal experimentation. All articles whose authors used Walker and Mason's model - with or without changes to the method in Wistar rats - were included in this study.

Results:

The search identified 45 mentions of Walker and Mason's model; however, after reading each summary, 20 were excluded (of which 5 due to duplicity). The inconsistencies observed after the scope review were: water temperature, length of time of exposure of the experimental model's skin to water, extent of the burnt area, and the description of the thickness/depth of the injury.

Conclusions:

Reproducibility of a scientific method is the basis to prove the veracity of the observed results. Thus, it is necessary to have a greater number of publications that adopt a reproducible scientific method, for this review found inconsistencies in the description of Walker and Mason's model.

A systematic review on the quality of measurement techniques for the assessment of burn wound depth or healing potential

PURPOSE

Reliable and valid assessment of burn wound depth or healing potential is essential to treatment decision-making, to provide a prognosis, and to compare studies evaluating different treatment modalities. The aim of this review was to critically appraise, compare and summarize the quality of relevant measurement properties of techniques that aim to assess burn wound depth or healing potential.

METHODS

A systematic literature search was performed using PubMed, EMBASE and Cochrane Library. Two reviewers independently evaluated the methodological quality of included articles using an adapted version of the Consensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist. A synthesis of evidence was performed to rate the measurement properties for each technique and to draw an overall conclusion on quality of the techniques.

RESULTS

Thirty-six articles were included, evaluating various techniques, classified as (1) laser Doppler techniques; (2) thermography or thermal imaging; (3) other measurement techniques. Strong evidence was found for adequate construct validity of laser Doppler imaging (LDI). Moderate evidence was found for adequate construct validity of thermography, videomicroscopy, and spatial frequency domain imaging (SFDI). Only two studies reported on the measurement property reliability. Furthermore, considerable variation was observed among comparator instruments.

CONCLUSIONS

Considering the evidence available, it appears that LDI is currently the most favorable technique; thereby assessing burn wound healing potential. Additional research is needed into thermography, videomicroscopy, and SFDI to evaluate their full potential. Future studies should focus on reliability and measurement error, and provide a precise description of which construct is aimed to measure.

Heterogeneity of mast cells and expression of Annexin A1 protein in a second degree burn model with silver sulfadiazine treatment

Mast cells (MCs) participate in all stages of skin healing and one of their mediators is the Annexin A1 protein (AnxA1), linked to inflammation, proliferation, migration and apoptosis processes, but not studied in thermal burns yet. Therefore, our objectives were to evaluate the behavior of MCs and AnxA1 in a second degree burn model, treated or not with silver sulfadiazine 1% (SDP 1%) and associated to macrophages quantification and cytokines dosages. MCs counts showed few cells in the early stages of repair but increased MCs in the final phases in the untreated group. The normal skin presented numerous tryptase-positive MCs that were reduced after burning in all analyzed periods. Differently, few chymase-positive MCs were observed in the early stages of healing, however, increased chymase-positive MCs were found at the final phase in the untreated group. MCs also showed high immunoreactivity for AnxA1 on day 3 in both groups. In the tissue there was a strong protein expression in the early stages of healing, but in the final phases only in the SDP treated animals. TNF-α, IL-1β, IL-6, IL-10 and MCP-1 levels and macrophages quantification were increased in inflammation and reepithelialization phases. Reduced IL-1β, IL-6 and IL-10 levels and numerous macrophages occurred in the treated animals during tissue repair. Our results indicate modulation in the profile of MCs and AnxA1expression during healing by the treatment with SDP 1%, pointing them as targets for therapeutic interventions on skin burns.

Multimodal evaluation of ultra-short laser pulses treatment for skin burn injuries

Thousands of people die every year from burn injuries. The aim of this study is to evaluate the feasibility of high intensity femtosecond lasers as an auxiliary treatment of skin burns. We used an in vivo animal model and monitored the healing process using 4 different imaging modalities: histology, Optical Coherence Tomography (OCT), Second Harmonic Generation (SHG), and Fourier Transform Infrared (FTIR) spectroscopy. 3 dorsal areas of 20 anesthetized Wistar rats were burned by water vapor exposure and subsequently treated either by classical surgical debridement, by laser ablation, or left without treatment. Skin burn tissues were non-invasively characterized by OCT images and biopsied for further histopathology analysis, SHG imaging and FTIR spectroscopy at 3, 5, 7 and 14 days after burn. The laser protocol was found as efficient as the classical treatment for promoting the healing process. The study concludes to the validation of femtosecond ultra-short pulses laser treatment for skinburns, with the advantage of minimizing operatory trauma.

Quantitative long-term measurements of burns in a rat model using Spatial Frequency Domain Imaging (SFDI) and Laser Speckle Imaging (LSI)

BACKGROUND AND OJECTIVES

The current standard for diagnosis of burn severity and subsequent wound healing is through clinical examination, which is highly subjective. Several new technologies are shifting focus to burn care in an attempt to help quantify not only burn depth but also the progress of healing. While accurate early assessment of partial thickness burns is critical for dictating the course of treatment, the ability to quantitatively monitor wound status over time is critical for understanding treatment efficacy. SFDI and LSI are both non-invasive imaging modalities that have been shown to have great diagnostic value for burn severity, but have yet to be tested over the course of wound healing.

METHODS

In this study, a hairless rat model (n = 6, 300-450 g) was used with a four pronged comb to create four identical partial thickness burns (superficial n = 3 and deep n = 3) that were used to monitor wound healing over a 28 days period. Weekly biopsies were taken for histological analysis to verify wound progression. Both SFDI and LSI were performed weekly to track the evolution of hemodynamic (blood flow and oxygen saturation) and structural (reduced scattering coefficient) properties for the burns.

RESULTS

LSI showed significant changes in blood flow from baseline to 220% in superficial and 165% in deep burns by day 7. In superficial burns, blood flow returned to baseline levels by day 28, but not for deep burns where blood flow remained elevated. Smaller increases in blood flow were also observed in the surrounding tissue over the same time period. Oxygen saturation values measured with SFDI showed a progressive increase from baseline values of 66-74% in superficial burns and 72% in deep burns by day 28. Additionally, SFDI showed significant decreases in the reduced scattering coefficient shortly after the burns were created. The scattering coefficient progressively decreased in the wound area, but returned towards baseline conditions at the end of the 28 days period. Scattering changes in the surrounding tissue remained constant despite the presence of hemodynamic changes.

CONCLUSIONS

Here, we show that LSI and SFDI are capable of monitoring changes in hemodynamic and scattering properties in burn wounds over a 28 days period. These results highlight the potential insights that can be gained by using non-invasive imaging technologies to study wound healing. Further development of these technologies could be revolutionary for wound monitoring and studying the efficacy of different treatments. Lasers Surg. Med. 49:293-304, 2017. © 2017 Wiley Periodicals, Inc.

Anti-inflammatory and burn injury wound healing properties of the shell of Haliotis diversicolor

Background

The shell of Haliotis diversicolor, or shijueming (SJM), is a type of traditional Chinese medicine. The SJM has appeared in historical records as early as the third and fourth centuries. Historical records have revealed that SJM had mainly been used to treat eye diseases. After the Qing Dynasty (1757), records had emerged, detailing the use of SJM for treating skin injuries, particularly for treating poorly managed ulcers or traumatic wounds. Furthermore, in our anti-inflammation-screening system, SJM significantly inhibited the expression of pro-inflammatory proteins. Previous studies have yet to adopt an animal model to verify the phenomenon and described in the historical records regarding the efficacy of SJM in promoting wound healing. Besides, the mechanism of wound healing effect of SJM is also not clear.

Methods

This study applied in vitro and in vivo models, tissue section analysis, and western blotting to evaluate the effect of SJM on wound healing. The RAW 264.7 cells were used in anti-inflammatory activity assay and phagocytic assay. Male Wistar rats were used to evaluate the effect of SJM on burn injury healing. A copper block (2 × 2 cm, 150 g) preheated to 165 °C in a dry bath was used to contact the skin area for 10 s, thus creating a full-thickness burn injury. The results were analyzed by hematoxylin and eosin staining, picrosirius red staining and Western blotting.

Results

The results revealed that in the in vitro model, the presence of SJM decreased the inducible nitric oxide synthase (iNOS) expression and enhanced the functions of macrophages. The results of the rat burn injury model revealed that SJM decreased neutrophil infiltration, promoted wound healing, thus increasing the collagen I content and promoting the expression of transforming growth factor-beta 1 (TGF-β1) protein. We speculate that the effect and mechanism of SJM on promoting wound healing is related to macrophage activation. In the inflammation phase, SJM alleviates inflammation by inhibiting iNOS expression and removing neutrophils through phagocytosis. Furthermore, SJM induces the secretion of TGF-β1, converting collagen during the tissue remodeling phase.

Conclusions

According to our review of relevant literature, this is the first study that applied an evidence-based method to verify that SJM alleviates inflammation, enhances phagocytosis, and triggers wound healing after burn injury. The study findings reveal that SJM provides a promising therapeutic option for treating burn injury.

Development of a guinea pig cutaneous radiation injury model using low penetrating X-rays

PURPOSE

A guinea pig skin model was developed to determine the dose-dependent response to soft X-ray radiation into the dermis.

MATERIALS AND METHODS

X-ray exposure (50 kVp) was defined to a 4.0 × 4.0 cm area on the lateral surface of a guinea pig using lead shielding. Guinea pigs were exposed to a single fraction of X-ray irradiation ranging from 25-79 Gy via an XRAD320ix Biological Irradiator with the collimator removed. Gross skin changes were measured using clinical assessments defined by the Kumar scale. Skin contracture was assessed, as well as histological evaluations.

RESULTS

Loss of dermal integrity was shown after a single dose of soft X-ray radiation at or above 32 Gy with the central 2.0 × 2.0 cm of the exposed site being the most affected. Hallmarks of the skin injury included moist desquamation, ulceration and wound contracture, as well as alterations in epithelium, dermis, muscle and adipose. Changes in the skin were time- and radiation dose-dependent. Full-thickness injury occurred without animal mortality or gross changes in the underlying organs.

CONCLUSIONS

The guinea pig is an appropriate small animal model for the short-term screening of countermeasures for cutaneous radiation injury (CRI).

Acute discrimination between superficial-partial and deep-partial thickness burns in a preclinical model with laser speckle imaging

A critical need exists for a robust method that enables early discrimination between superficial-partial and deep-partial thickness burn wounds. In this study, we report on the use of laser speckle imaging (LSI), a simple, non-invasive, optical imaging modality, to measure acute blood flow dynamics in a preclinical burn model. We used a heated brass comb to induce burns of varying severity to nine rats and collected raw speckle reflectance images over the course of three hours after burn. We induced a total of 12 superficial-partial and 18 deep-partial thickness burn wounds. At 3h after burn we observed a 28% and 44% decrease in measured blood flow for superficial-partial and deep-partial thickness burns, respectively, and that these reductions were significantly different (p=0.00007). This preliminary data suggests the potential role of LSI in the clinical management of burn wounds.

Utilization of laser Doppler flowmetry and tissue spectrophotometry for burn depth assessment using a miniature swine model

Currently, the diagnosis of burn depth is primarily based on a visual assessment and can be dependent on the surgeons' experience. The goal of this study was to determine the ability of laser Doppler flowmeter combined with a tissue spectrophotometer to discriminate burn depth in a miniature swine burn model. Burn injuries of varying depth, including superficial-partial, deep-partial, and full thickness, were created in seven Göttingen minipigs using an aluminium bar (100 °C), which was applied to the abdominal skin for periods of 1, 3, 6, 12, 30, and 60 seconds with gravity alone. The depth of injury was evaluated histologically using hematoxylin and eosin staining. All burns were assessed 3 hours after injury using a device that combines a laser light and a white light to determine blood flow, hemoglobin oxygenation, and relative amount of hemoglobin. The blood flow (41 vs. 124 arbitrary units [AU]) and relative amount of hemoglobin (32 vs. 52 AU) were significantly lower in full thickness compared with superficial-partial thickness burns. However, no significant differences in hemoglobin oxygenation were observed between these depths of burns (61 vs. 60%). These results show the ability of laser Doppler flowmeter and tissue spectrophotometer in combination to discriminate between various depths of injury in the minipig model, suggesting that this device may offer a valuable tool for burn depth assessment influencing burn management.

In vitro burn model illustrating heat conduction patterns using compressed thermal papers

To date, heat conduction from heat sources to tissue has been estimated by complex mathematical modeling. In the present study, we developed an intuitive in vitro skin burn model that illustrates heat conduction patterns inside the skin. This was composed of tightly compressed thermal papers with compression frames. Heat flow through the model left a trace by changing the color of thermal papers. These were digitized and three-dimensionally reconstituted to reproduce the heat conduction patterns in the skin. For standardization, we validated K91HG-CE thermal paper using a printout test and bivariate correlation analysis. We measured the papers' physical properties and calculated the estimated depth of heat conduction using Fourier's equation. Through contact burns of 5, 10, 15, 20, and 30 seconds on porcine skin and our burn model using a heated brass comb, and comparing the burn wound and heat conduction trace, we validated our model. The heat conduction pattern correlation analysis (intraclass correlation coefficient: 0.846, p < 0.001) and the heat conduction depth correlation analysis (intraclass correlation coefficient: 0.93, p < 0.001) showed statistically significant high correlations between the porcine burn wound and our model. Our model showed good correlation with porcine skin burn injury and replicated its heat conduction patterns.

Decomposition and entomological colonization of charred bodies - a pilot study

Aim

To use forensic entomological approach to estimate the post mortem interval (PMI) in burnt remains.

Methods

Two experiments were performed in a field in the outskirts of Milan, in winter and summer 2007. Four 60-kg pigs were used: two for each experiment. One pig carcass was burnt until it reached the level 2-3 of the Glassman-Crow scale and the not-burnt carcass was used as a control. In order to describe the decomposition process and to collect the data useful for minimum PMI estimation, macroscopic, histological, and entomological analyses were performed.

Results

In the winter part of the experiment, the first insect activity on the burnt carcass began in the third week (Calliphora vomitoria) and at the beginning of the fourth week an increase in the number of species was observed. In the summer part, adult flies and first instar maggots (Phormia regina) appeared a few minutes/hours after the carcass exposure. Both in winter and summer, flies belonging to the first colonization wave (Calliphoridae) appeared on burnt and control pigs at the same time, whereas other species (Diptera and Coleoptera) appeared earlier on burnt pigs.

Conclusion

In forensic practice, burnt bodies are among the most neglected fields of entomological research, since they are supposed to be an inadequate substratum for insect colonization. Entomological approach for PMI estimation proved to be useful, although further studies on larger samples are needed.

Evaluation of the effects of honey on acute-phase deep burn wounds

This study aimed to clarify the effects of honey on acute-phase deep burn wounds. Two deep burn wounds were created on mice which were divided into four groups: no treatment, silver sulfadiazine, manuka honey, and Japanese acacia honey. Wound sizes were calculated as expanded wound areas and sampled 30 minutes and 1–4 days after wounding for histological observation. The wound sections were subjected to hematoxylin and eosin and immunohistological staining to detect necrotic cells, apoptotic cells, neutrophils, and macrophages. The no treatment group formed a scar. The redness around the wound edges in the silver sulfadiazine group was the most intense. All groups exhibited increased wound areas after wounding. The proportions of necrotic cells and the numbers of neutrophils in the manuka and acacia honey groups were lower than those in the no treatment and silver sulfadiazine groups until day 3; however, there were no significant differences between all groups on day 4. These results show that honey treatment on deep burn wounds cannot prevent wound progression. Moreover, comparing our observations with those of Jackson, there are some differences between humans and animals in this regard, and the zone of hyperemia and its surrounding area fall into necrosis, which contributes to burn wound progression.

Laserterapia e microcorrente na cicatrização de queimadura em ratos: terapias associadas ou isoladas?

Este estudo teve o objetivo de investigar se há diferenças entre as terapias associadas e isoladas do laser e microcorrentes no reparo de lesão por queimadura em ratos. Um total de 40 animais foi dividido aleatoriamente em quatro grupos: grupo controle (GC); grupo microcorrente (GM), grupo laser (GL) e grupo laser/microcorrente (GLM), tratados com laser associado a microcorrentes. Após lesões térmicas induzidas no dorso do animal, foi realizado um total de dez dias de tratamento. Amostras do tecido foram coletadas para estudo histopatológico semiquantitativo com Hematoxilina Eosina e Tricrômico de Masson. Foram utilizados os testes de Kruskal-Wallis e post-hoc de Dunn. Houve diferença significativa entre os grupos para a produção de fibroblastos (p=0,0003), colágeno (p=0,0153), neoangiogênese (p=0,0031) e anexos cutâneos (p=0,0004). Na análise histológica semiquantitativa, o GLM apresentou valores menores nos parâmetros histológicos de presença de colágeno, número de fibroblastos e anexos cutâneos (p<0,05) em relação às terapias isoladas, exceto para a neoangiogênese, cujos valores da terapia associada foram semelhantes aos grupos de terapia com modalidade única. Apesar do laser e da microcorrente separadamente terem efeitos benéficos para a cicatrização tecidual, a associação das modalidades parece ter diminuído a ação de reparo. No entanto, sugere-se que a associação destes recursos parece diminuir os efeitos do tratamento quando se comparam os grupos de modalidade única.

Pharmacologic modification to resuscitation fluid after thermal injury--is drotrecogin alfa the answer to arrest burn depth progression?

HYPOTHESIS

The addition of drotrecogin alfa (DA), an anti-inflammatory useful in septic shock, to standard burn shock resuscitation fluids will protect burned, injured skin from further injury.

METHODS

Anesthetized animals were subjected to a standardized burn pattern by applying a branding iron to 10 different locations on the back of the rat for 1 seconds to 14 seconds, creating a range of burn depths and severities.

DESIGN

Animal burn shock and resuscitation model.

PARTICIPANTS

Thirty-one male adult Sprague-Dawley rats.

INTERVENTIONS

Control animals were resuscitated with lactated Ringer's solution (LRS) at 2 mL/kg/percent total body surface area/24 h; experimental animals received LRS plus DA 24 microg/kg/h (LRS + DA).

OUTCOME MEASURES

Perfusion to each burned area was assessed using a laser Doppler imaging technology. Punch biopsies at each burned area were stained with hematoxylin and eosin and assessed for burn depth and for inflammation using previously reported measures. Samples from 14 animals were stained for terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and caspase-3 (apoptosis markers).

RESULTS

Increasing branding iron contact times worsened perfusion, burn depth, and apoptotic ratios. There was no correlation between inflammatory markers and burn contact time. The addition of DA leads to worse perfusion, deeper burns, worse inflammation, and decreased apoptotic ratios.

CONCLUSIONS

Laser Doppler imaging is a useful technology to assess burn depth. The addition of DA to traditional resuscitation fluids for burn shock is deleterious to the injured, burned skin. Modifying the traditional burn shock resuscitation fluids, although intellectually attractive, needs to be rigorously studied.