Full-thickness Thermal Injury Research Articles

36. Spironolactone Mitigates Fibrosis and Improves Healing of Burn Wounds

Purpose: Adhesion, contracture, and the formation of disfiguring, hypertrophic scars remain some of the most recalcitrant problems in care of the burned patient. The central pathology driving fibrosis is an imbalance of extracellular matrix (ECM). The mineralocorticoid receptor (MR) is a nuclear receptor with shared ligand-activity from both its primary activator, aldosterone, and glucocorticoids and has cell specific effects on proliferation, migration, and ECM production in fibroblasts and keratinocytes. Here we demonstrate that MR-inhibition with FDA approved spironolactone enhances epithelialization healing and mitigates hypertrophic collagen deposition after burns in mice. Methods: Female athymic mice sustained bilateral 1 cm full-thickness thermal injury and were stratified into either a) vehicle, b) spironolactone, c) aldosterone, or d) aldosterone + spironolactone. Aldosterone applied via subcutaneous pump (Alzet) spironolactone delivered intraperitoneally. Mice followed photographically for 4-to-6-weeks. At sacrifice wound biopsies were collected for H&E, Trichrome, and protein. An additional subset of samples were assessed via Pentachrome staining to assess relative ratio of collagen, fibrin, and elastic fibers. Pentachrome samples were analyzed using ImageJ (RGB Hue threshold) to isolate elastin, GAG and collagen for quantification. Results: Histologic evaluation of healing wounds from burned mice demonstrated persistence of inflammation, wound edema, and immature ECM. In mice treated with spironolactone this effect if alleviated by 4-weeks post-injury concurrent with gross findings of rapid wound epithelialization. Spironolactone treatment additionally enhanced gross and histologic evidence of scar resolution and resulted in a decreased in collagen staining vs. controls. Conclusion: We found a significant early improvement in wound epithelialization with spironolactone therapy. This suggests a potentially distinct effect from the proposed ECM-modifying strategy hypothesized. More analysis is needed but this data supports that MR-inhibition may be a valuable new therapeutic in treatment of burn scars.

P31. CONTROL OF THE MINERALOCORTICOID RECEPTOR ENHANCES WOUND HEALING AND MITIGATE FIBROSIS AFTER THERMAL INJURY

PURPOSE: Adhesion, contracture, and the formation of disfiguring, hypertrophic scars remain some of the most recalcitrant problems in care of the burned patient. The central pathology driving fibrosis is an imbalance of extracellular matrix (ECM). The mineralocorticoid receptor (MR) is a nuclear receptor with shared ligand-activity from both its primary activator, aldosterone, and glucocorticoids and has cell specific effects on proliferation, migration, and ECM production in fibroblasts and keratinocytes. Here we demonstrate that MR-inhibition with FDA approved spironolactone enhances epithelialization healing and mitigates hypertrophic collagen deposition after burns in mice. METHODS: Female athymic mice sustained bilateral 1 cm full-thickness thermal injury and were stratified into either a) vehicle, b) spironolactone, c) aldosterone, or d) aldosterone + spironolactone. Aldosterone applied via subcutaneous pump (Alzet) spironolactone delivered intraperitoneally. Mice followed photographically for 4-to-6-weeks. At sacrifice wound biopsies were collected for H&E, Trichrome, and protein. RESULTS: Histologic evaluation of healing wounds from burned mice demonstrated persistence of inflammation, wound edema, and immature ECM. In mice treated with spironolactone this effect if alleviated by 4-weeks post-injury concurrent with gross findings of rapid wound epithelialization. Spironolactone treatment additionally enhanced gross and histologic evidence of scar resolution and resulted in a decreased in collagen staining vs. controls. CONCLUSION: We found a significant early improvement in wound epithelialization with spironolactone therapy. This suggests a potentially distinct effect from the proposed ECM-modifying strategy hypothesized. More analysis is needed but this data supports that MR-inhibition may be a valuable new therapeutic in treatment of burn scars.

Evaluation of KP-1199: a novel acetaminophen analog for hemostatic function and antinociceptive effects.

Acetaminophen (APAP) is a widely self-prescribed analgesic for mild to moderate pain, but overdose or repeat doses can lead to liver injury and death. Kalyra Pharmaceuticals has developed a novel APAP analog, KP-1199, currently in Phase 1 clinical studies, which lacks hepatotoxicity. In this study, the authors evaluated the antinociceptive effect of KP-1199 on thermal injury-induced nociceptive behaviors as well as hemostatic parameters using human blood samples. Full-thickness thermal injury was induced in anesthetized adult male Sprague-Dawley rats. On day 7 post-injury, KP-1199 (30 and 60 mg/kg) or APAP (60 mg/kg) was administered orally. Antinociception of KP-1199 and APAP were assessed at multiple time points using Hargreaves' test. In separate experiments, human whole blood was collected and treated with either KP-1199, APAP, or Vehicle (citrate buffer) at 1× (214 μg/ml) and 10× (2140 μg/ml) concentrations. The treated blood samples were assessed for: clotting function, thrombin generation, and platelet activation. APAP did not produce antinociceptive activity. KP-1199 treatment significantly increased the nociceptive threshold, and the antinociceptive activity persisted up to 3h post-treatment. In human samples, 10× APAP caused significantly prolonged clotting times and increased platelet activation, whereas KP-1199 had caused no negative effects on either parameter tested. These results suggest that KP-1199 possesses antinociceptive activity in a rat model of thermal injury. Since KP-1199 does not induce platelet activation or inhibit coagulation, it presents an attractive alternative to APAP for analgesia, especially for battlefield or surgical scenarios where blood loss and blood clotting are of concern.

Mitochondrial DNA-Induced Inflammatory Responses and Lung Injury in Thermal Injury Murine Model: Protective Effect of Cyclosporine-A.

Burn trauma is generally associated with profound inflammation and organ injuries, especially the lung. Damage-associated molecular patterns (DAMPs), such as mitochondrial DNA (mtDNA), released after tissue injuries, play a crucial role in the development of the inflammation. The aim of our study was to investigate the protective profiles of cyclosporine-A (CsA) in murine models with thermal injury. We studied 24 C57BL/6 mice which were randomly subjected to four groups: a sham-operation group (SO group, n = 6), an experiment group (a full-thickness thermal injury covered 30% of the TBSA, n = 6), a low-CsA group (injection of 2.5 mg/kg of CsA 15 min before the thermal injury, n = 6) and a high-CsA group (injection of 25 mg/kg of CsA 15 min before the thermal injury, n = 6). Systemic inflammatory mediators and plasma mtDNA were measured while lung injury was evaluated pathologically and cytosolic cytochrome c and mtDNA were detected. Noticeable increases in concentration of mtDNA and inflammatory mediators were obtained in the experiment group and two CsA groups comparing with the SO group (P < .05). There were significant decreases in the concentrations of mtDNA and inflammatory mediators with increasing doses of CsA (P < .05). Similarly, severity of lung injury was mitigated with increasing doses of CsA. Meanwhile, CsA also attenuated oxidative stress and release of cytochrome c and mtDNA in the lung tissue on a dose-dependent manner (P < .05). Our results suggested mtDNA contributes to the development of thermal injury-induced inflammation and lung injury. CsA might exert dual protective effects, reducing the release of mtDNA and limiting the mtDNA-induced mitochondrial dysfunction in the lung, on the thermal injury-induced acute lung injury.

Optimal skin regeneration after full thickness thermal burn injury in the spiny mouse, Acomys cahirinus

The spiny mouse, Acomys cahirinus, shows remarkable regenerative abilities after excisional skin wounding by regrowing hair, sebaceous glands, smooth muscle, skeletal muscle and dermis without scarring. We have asked here whether this same regeneration can be seen after full thickness thermal burn injuries. Using a brass rod thermal injury model we show that in contrast to the lab mouse, Mus musculus, which forms a thick scar covered by a hairless epidermis, the spiny mouse regenerates all the tissues injured — skeletal muscle, dermis, hairs, sebaceous glands such that the skin is externally indistinguishable from its original appearance. Re-epithelialization is faster in Acomys than in Mus but ingression and proliferation of dermal fibroblasts is the same in both species. After 3 weeks the wound epithelium of Acomys has developed a covering of new hair follicles in contrast to Mus. The skeletal muscle of the panniculus carnosus in Mus shows some regeneration but it is incomplete and fibrotic whereas the Acomys muscle is replaced perfectly. There are differences in the macrophage profiles which invade the damaged tissues such as the absence of F4/80 or MOMA-2 +ve cells in Acomys which likely reflect different cytokine profiles resulting from the same injury in these two species.

Antinociceptive effects of pluronic lecithin organo (PLO)-opioid gels in rats with thermal injury

Opioids are extensively used as analgesics to control burn pain. However, systemic administration of opioids induces multiple adverse effects that are primarily CNS mediated. Alternately, topical application of low dose of opioids directly at the site of injury could attenuate pain while avoiding CNS-mediated side effects. Pluronic lecithin organogels (PLO) have been extensively used as vehicles to deliver topical drugs. In this study, we for the first time assessed the analgesic efficacy of three opioid-PLO formulations (fentanyl, methadone & morphine) in a rat full-thickness thermal injury (FTTI) pain model. Experiments were performed using 44 adult male Sprague-Dawley rats. A single 0.1mL topical application of either morphine (5mg/mL, n=6), fentanyl (10μg/mL, n=8), methadone gel (5mg/mL, n=8), ketamine (50mg/mL, n=6), saline (0.1mL, n=8) or PLO gel alone (0.1mL, n=8) was administered to the plantar surface of the injured hindpaw on days 4 and 7 following thermal injury. The anti-hyperalgesic effects were then measured (5, 15, 30, 60 and 120min post-drug application) using the Hargreaves’ thermal test. All three opioids produced statistically significant increases in paw withdrawal latency (PWL), taken as a measure of anti-hyperalgesia, in comparison to saline-treated group (P<0.05), at both 4 and 7days post injury, with fentanyl showing greatest efficacy. Taken together, a low dose of topical application of opioids can reduce thermal hyperalgesia in a rat hindpaw FTTI model, supporting the development of topical formulations of these drugs for burn pain treatment in the clinic.

Thermal injury model in the rabbit ear with quantifiable burn progression and hypertrophic scar.

Hypertrophic scar is a major clinical outcome of deep-partial thickness to full thickness thermal burn injury. Appropriate animal models are a limitation to burn research due to the lack of, or access to, animal models which address the endpoint of hypertrophic scar. Lower species, such as rodents, heal mainly by contracture, which limits the duration of study. Higher species, such as pigs, heal more similarly to humans, but are associated with high cost, long duration for scar development, challenges in quantifying scar hypertrophy, and poor manageability. Here, we present a quantifiable deep-partial thickness burn model in the rabbit ear. Burns were created using a dry-heated brass rod for 10 and 20 seconds at 90 °C. At the time of eschar excision on day 3, excisional wounds were made on the contralateral ear for comparison. Burn wound progression, in which the wound size expands over time is a major distinction between excisional and thermal injuries, was quantified at 1 hour and 3 days after the injuries using calibrated photographs and histology and the size of the wounds was found to be unchanged from the initial wound size at 1 hour, but 10% in the 20 seconds burn wounds at 3 days. A quantifiable hypertrophic scar, measured by histology as the scar elevation index, was present in both 20 seconds burn wounds and excisional wounds at day 35. ImageJ measurements revealed that the 20 seconds burn wound scars were 22% larger than the excisional wound scars and the 20 seconds burn scar area measurements from histology were 26% greater than in the excisional wound scar. The ability to measure both burn progression and scar hypertrophy over a 35-day time frame suits this model to screening early intervention burn wound therapeutics or scar treatments in a burn-specific scar model.

Mitochondrial DNA-Induced Inflammatory Responses and Lung Injury in Thermal Injury Rat Model: Protective Effect of Epigallocatechin Gallate.

Lungs are easily damaged by the inflammatory responses induced after extensive burns. The aim here was to investigate the protective role of epigallocatechin gallate (EGCG) in mitochondrial DNA (mtDNA)-mediated inflammatory responses and acute respiratory distress syndrome (ARDS) in a rat model of thermal injury. Male Sprague-Dawley rats were randomly assigned to five groups. In the first experiment, a full-thickness thermal injury or control procedure, covering 30% of the TBSA, was inflicted on three groups designated as the thermal injury, EGCG, and sham control groups. In the second experiment, another two groups were established by transfusion with either mtDNA (mtDNA group) or phosphate-buffered saline (phosphate-buffered saline group). Blood samples and lung tissue from all five groups were collected and the plasma concentrations of mtDNA and inflammatory mediators were measured. Bronchoalveolar lavage fluid was collected and histological analysis of the lung tissue was performed to evaluate the severity of ARDS. Significant increases in mtDNA and inflammatory mediator plasma concentrations were seen in the thermal injury and EGCG groups when compared with controls (P < .05). The plasma concentrations of mtDNA and inflammatory mediators were significantly decreased after the administration of EGCG (P < .05). EGCG also significantly reduced the severity of acute lung injury (P < .05). Intravenous administration of mtDNA significantly increased concentrations of inflammatory mediators and caused severe ARDS (P < .05). Our results suggest that mtDNA is important for thermal injury-induced inflammation and associated ARDS. EGCG possesses anti-inflammatory and lung-protective properties, and might act by limiting mtDNA release after thermal injury.

Local Resiniferatoxin Induces Long-Lasting Analgesia in a Rat Model of Full Thickness Thermal Injury.

Opioid-based analgesics are a major component of the lengthy pain management of burn patients, including military service members, but are problematic due to central nervous system-mediated side effects. Peripheral analgesia via targeted ablation of nociceptive nerve endings that express the transient receptor potential vanilloid channel 1 (TRPV1) may provide an improved approach. We hypothesized that local injection of the TRPV1 agonist resiniferatoxin (RTX) would produce long-lasting analgesia in a rat model of pain associated with burn injury. Baseline sensitivities to thermal and mechanical stimuli were measured in male and female Sprague-Dawley rats. Under anesthesia, a 100 °C metal probe was placed on the right hind paw for 30 seconds, and sensitivity was reassessed 72 hours following injury. Rats received RTX (0.25 μg/100 μL; ipl) into the injured hind paw, and sensitivity was reassessed across three weeks. Tissues were collected from a separate group of rats at 24 hours and/or one week post-RTX for pathological analyses of the injured hind paw, dorsal spinal cord c-Fos, and primary afferent neuropeptide immunoreactivity. Local RTX reversed burn pain behaviors within 24 hours, which lasted through recovery at three weeks. At one week following RTX, decreased c-Fos and primary afferent neuropeptide immunoreactivities were observed in the dorsal horn, while plantar burn pathology was unaltered. These results indicate that local RTX induces long-lasting analgesia in a rat model of pain associated with burn. While opioids are undesirable in trauma patients due to side effects, RTX may provide valuable long-term, nonopioid analgesia for burn patients.

Development of a combined radiation and full thickness burn injury minipig model to study the effects of uncultured adipose-derived regenerative cell therapy in wound healing

Purpose: To develop an approach that models the cutaneous healing that occurs in a patient with full thickness thermal burn injury complicated by total body radiation exposure sufficient to induce sub-lethal prodromal symptoms. An assessment of the effects of an autologous cell therapy on wound healing on thermal burn injury with concomitant radiation exposure was used to validate the utility of the model.Methods: Göttingen minipigs were subjected to a 1.2 Gy total body irradiation by exposure to a 6 MV X-ray linear accelerator followed by ∼10 cm2 full thickness burns (pre-heated brass block with calibrated spring). Three days after injury, wounds were excised to the underlying fascia and each animal was randomized to receive treatment with autologous adipose-derived regenerative cells (ADRC) delivered by local or intravenous injection, or vehicle control. Blood counts were used to assess radiation-induced marrow suppression. All animals were followed using digital imaging to assess wound healing. Full-thickness biopsies were obtained at 7, 14, 21 and 30 days’ post-treatment.Results: Compared to animals receiving burn injury alone, significant transient neutropenia and thrombocytopenia were observed in irradiated subjects with average neutrophil nadir of 0.79 × 103/μl (day 15) and platelet nadir of 60 × 103/μl (day 12). Wound closure through a combination of contraction and epithelialization from the wound edges occurred over a period of approximately 28 days’ post excision and treatment. Re-epithelialization was accelerated in wounds treated with ADRC (mean 3.5-fold increase at 2 weeks post-treatment relative to control). This acceleration was accompanied by an average 67% increase in blood vessel density and 30% increase in matrix (collagen) deposition. Similar results were observed when ADRC were injected either directly into the wound or by intravenous administration.Conclusions: Although preliminary, this study provides a reproducible minipig model of thermal burn injury complicated by myelosuppressive total body irradiation that utilizes standardized procedures to evaluate novel countermeasures for potential use following attack by an improvised nuclear device.

Prior stress exposure increases pain behaviors in a rat model of full thickness thermal injury

Thermal burns among individuals working in highly stressful environments, such as firefighters and military Service Members, are common. Evidence suggests that pre-injury stress may exaggerate pain following thermal injury; however current animal models of burn have not evaluated the potential influence of pre-burn stress. This sham-controlled study evaluated the influence of prior stress exposure on post-burn thermal and mechanical sensitivity in male Sprague-Dawley rats. Rats were exposed to 20min of inescapable swim stress or sham stress once per day for three days. Exposure to inescapable swim stress (1) increased the intensity and duration of thermal hyperalgesia after subsequent burn and (2) accelerated the onset of thermal hyperalgesia and mechanical allodynia after subsequent burn. This stress-induced exacerbation of pain sensitivity was reversed by pretreatment and concurrent treatment with the serotonin-norepinephrine reuptake inhibitor (SNRI) duloxetine. These data suggest a better understanding of mechanisms by which prior stress augments pain after thermal burn may lead to improved pain treatments for burn survivors.

Tetrodotoxin suppresses thermal hyperalgesia and mechanical allodynia in a rat full thickness thermal injury pain model

Burn injuries have been identified as the primary cause of injury in 5% of U.S. military personnel evacuated from Operations Iraqi Freedom and Enduring Freedom. Severe burn-associated pain is typically treated with opioids such as fentanyl, morphine, and methadone. Side effects of opioids include respiratory depression, cardiac depression, decrease in motor and cognitive function, as well as the development of hyperalgesia, tolerance and dependence. These effects have led us to search for novel analgesics for the treatment of burn-associated pain in wounded combat service members. Tetrodotoxin (TTX) is a selective voltage-gated sodium channel blocker currently in clinical trials as an analgesic. A phase 3 clinical trial for cancer-related pain has been completed and phase 3 clinical trials on chemotherapy-induced neuropathic pain are planned. It has also been shown in mice to inhibit the development of chemotherapy-induced neuropathic pain. TTX was originally identified as a neurotoxin in marine animals but has now been shown to be safe in humans at therapeutic doses. The antinociceptive effects of TTX are thought to be due to inhibition of Na+ ion influx required for initiation and conduction of nociceptive impulses. One TTX sensitive sodium channel, Nav1.7, has been shown to be essential in lowering the heat pain threshold after burn injuries. To date, the analgesic effect of TTX has not been tested in burn-associated pain. Male Sprague-Dawley rats were subjected to a full thickness thermal injury on the right hind paw. TTX (8μg/kg) was administered once a day systemically by subcutaneous injection beginning 3 days post thermal injury and continued through 7 days post thermal injury. Thermal hyperalgesia and mechanical allodynia were assessed 60 and 120min post injection on each day of TTX treatment. TTX significantly reduced thermal hyperalgesia at all days tested and had a less robust, but statistically significant suppressive effect on mechanical allodynia. These results suggest that systemic TTX may be an effective, rapidly acting analgesic for battlefield burn injuries and has the potential for replacing or reducing the need for opioid analgesics.

(362) Combined serotonin and norepinephrine reuptake inhibition reduces the effects of stress on post-injury pain behaviors in a rat model of burn injury

Even with currently available medications, moderate or severe pain after burn injuries is typical and remains a major clinical challenge. There is an urgent need for improvement in the understanding of mechanisms that mediate pain after thermal burn injury in order to reduce patient suffering and enhance recovery. Previous studies suggest that stress may exaggerate pain processing, reduce sensitivity to pain therapeutics, and increase the probability of developing chronic post-burn pain. However, the potential influence of stress has not been incorporated into animal models of thermal burn injury. This sham-controlled study evaluated the influence of prior stress exposure on post-burn thermal and mechanical sensitivity in male Sprague-Dawley rats. Rats were exposed to twenty minutes of inescapable swim stress or sham stress once per day for three days. Prior to the first session, and 24 hours following the third session, mechanical and thermal hindpaw sensitivity was recorded. Pain behaviors were determined as the force required to elicit voluntary withdrawal of the hindpaw from a non-noxious mechanical stimulus and the latency to remove the hindpaw from a noxious thermal stimulus. Rats then received a standardized full thickness thermal injury to the right hindpaw and subsequent pain behaviors were recorded at 24 hours, 96 hours, 1 week, 2 weeks, and 3 weeks following thermal injury. Exposure to inescapable swim stress (1) increased the intensity and duration of thermal hyperalgesia after subsequent burn injury and (2) accelerated the onset of both thermal hyperalgesia and mechanical allodynia after subsequent burn injury. This stress-induced exacerbation of pain sensitivity was reversed by seven days of pretreatment with the SNRI, duloxetine. These data suggest a better understanding of mechanisms by which prior stress augments pain after thermal burn injury may lead to improved pain treatments for burn injury survivors. Even with currently available medications, moderate or severe pain after burn injuries is typical and remains a major clinical challenge. There is an urgent need for improvement in the understanding of mechanisms that mediate pain after thermal burn injury in order to reduce patient suffering and enhance recovery. Previous studies suggest that stress may exaggerate pain processing, reduce sensitivity to pain therapeutics, and increase the probability of developing chronic post-burn pain. However, the potential influence of stress has not been incorporated into animal models of thermal burn injury. This sham-controlled study evaluated the influence of prior stress exposure on post-burn thermal and mechanical sensitivity in male Sprague-Dawley rats. Rats were exposed to twenty minutes of inescapable swim stress or sham stress once per day for three days. Prior to the first session, and 24 hours following the third session, mechanical and thermal hindpaw sensitivity was recorded. Pain behaviors were determined as the force required to elicit voluntary withdrawal of the hindpaw from a non-noxious mechanical stimulus and the latency to remove the hindpaw from a noxious thermal stimulus. Rats then received a standardized full thickness thermal injury to the right hindpaw and subsequent pain behaviors were recorded at 24 hours, 96 hours, 1 week, 2 weeks, and 3 weeks following thermal injury. Exposure to inescapable swim stress (1) increased the intensity and duration of thermal hyperalgesia after subsequent burn injury and (2) accelerated the onset of both thermal hyperalgesia and mechanical allodynia after subsequent burn injury. This stress-induced exacerbation of pain sensitivity was reversed by seven days of pretreatment with the SNRI, duloxetine. These data suggest a better understanding of mechanisms by which prior stress augments pain after thermal burn injury may lead to improved pain treatments for burn injury survivors.

Full-Thickness Thermal Injury Delays Wound Closure in a Murine Model.

Objective: The contemporary treatment of a full-thickness burn consists of early eschar excision followed by immediate closure of the open wound using autologous skin. However, most animal models study burn wound healing with the persistence of the burn eschar. Our goal is to characterize a murine model of burn eschar excision to study wound closure kinetics. Approach: C57BL/6 male mice were divided into three groups: contact burn, scald burn, or unburned control. Mice were burned at 80°C for 5, 10, or 20 s. After 2 days, the eschar was excised and wound closure was documented until postexcision day 13. Biopsies were examined for structural morphology and α-smooth muscle actin. In a subsequent interval-excision experiment (80°C scald for 10 s), the burn eschar was excised after 5 or 10 days postburn to determine the effect of a prolonged inflammatory focus. Results: Histology of both contact and scald burns revealed characteristics of a full-thickness injury marked by collagen coagulation and tissue necrosis. Excision at 2 days after a 20-s burn from either scald or contact showed significant delay in wound closure. Interval excision of the eschar, 5 or 10 days postburn, also showed significant delay in wound closure. Both interval-excision groups showed prolonged inflammation and increased myofibroblasts. Innovation and Conclusions: We have described the kinetics of wound closure in a murine model of a full-thickness burn excision. Both contact and scald full-thickness burn resulted in significantly delayed wound closure. In addition, prolonged interval-excision of the eschar appeared to increase and prolong inflammation.

A rat model of full thickness thermal injury characterized by thermal hyperalgesia, mechanical allodynia, pronociceptive peptide release and tramadol analgesia

Opioid-related side effects are problematic for burn patients. Dual mechanism therapeutics targeting opioid and non-opioid mechanisms may have reduced side effects with similar analgesic efficacy. Tramadol combines mu opioid receptor agonism with norepinephrine reuptake inhibition and has been effective in treating some types of pain. The effectiveness of tramadol in treating pain associated with burns is unclear. We hypothesized that tramadol is effective in reducing thermal injury-evoked pain behaviors in a rat model. Rats were anesthetized and a 100°C metal probe was placed on the hindpaw for 30s to induce a full thickness thermal injury. A subset of rats was perfusion fixed and hindpaw tissue and spinal cord collected for anatomical analysis. Rats received morphine (5mg/kg; i.p.), tramadol (10–30mg/kg; i.p.) or vehicle and latency to paw withdrawal from a noxious thermal or non-noxious mechanical stimulus was recorded every 10min over 70min and again at 2h. We report that pain behaviors developed within 48h and peaked at 1 week; paralleled by enhanced expression of pronociceptive neuropeptides in the spinal cord. Morphine and tramadol significantly attenuated hyperalgesia and allodynia, while not significantly altering motor coordination/sedation. These data indicate dual mechanism therapeutics may be effective for treating pain associated with burns.

The anti-inflammatory and analgesic activity of curcumin in a rat model of full thickness thermal injury

The anti-inflammatory and analgesic activity of curcumin in a rat model of full thickness thermal injury

Radiation Combined With Thermal Injury Induces Immature Myeloid Cells

The continued development of nuclear weapons and the potential for thermonuclear injury necessitates the further understanding of the immune consequences after radiation combined with injury (RCI). We hypothesized that sublethal ionization radiation exposure combined with a full-thickness thermal injury would result in the production of immature myeloid cells. Mice underwent either a full-thickness contact burn of 20% total body surface area or sham procedure followed by a single whole-body dose of 5-Gy radiation. Serum, spleen, and peripheral lymph nodes were harvested at 3 and 14 days after injury. Flow cytometry was performed to identify and characterize adaptive and innate cell compartments. Elevated proinflammatory and anti-inflammatory serum cytokines and profound leukopenia were observed after RCI. A population of cells with dual expression of the cell surface markers Gr-1 and CD11b were identified in all experimental groups, but were significantly elevated after burn alone and RCI at 14 days after injury. In contrast to the T-cell-suppressive nature of myeloid-derived suppressor cells found after trauma and sepsis, myeloid cells after RCI augmented T-cell proliferation and were associated with a weak but significant increase in interferon γ and a decrease in interleukin 10. This is consistent with previous work in burn injury indicating that a myeloid-derived suppressor cell-like population increases innate immunity. Radiation combined injury results in the increase in distinct populations of Gr-1CD11b cells within the secondary lymphoid organs, and we propose these immature inflammatory myeloid cells provide innate immunity to the severely injured and immunocompromised host.

Expressions of endoplasmic reticulum stress associated proteins in livers of severely burned rats

To explore the expression of endoplasmic reticulum stress (ERS) associated proteins in livers of severely burned rats and examine its potential significance. Sixty-four Wistar rats were randomly divided into the control and burn groups (30% total body surface area full-thickness thermal injury) (n = 32 each). Livers were harvested at Day 1, 4, 7, 14 post-burn. Western blot was used to detect the expressions of endoplasmic reticulum stress associated proteins glucose regulated protein 78 (GRP78), C/EBP-homologous protein (CHOP), active caspase-12 and active caspase-3. Hepatic apoptosis was assessed by the assay of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). Compared with the control group, the expression of GRP78 became elevated at Day 1, 4, 7, 14 post-burn (1.29 ± 0.11 vs 1.00 ± 0.00, 1.28 ± 0.12 vs 0.95 ± 0.16, 1.29 ± 0.14 vs 0.93 ± 0.06, 1.41 ± 0.17 vs 1.02 ± 0.13 respectively); the expression of CHOP was higher at Day 1, 4 (1.72 ± 0.07 vs 1.00 ± 0.00, 1.82 ± 0.18 vs 1.46 ± 0.08 respectively) while active caspase-12 and active caspase-3 increased at Day 1, 4, 7 post-burn (2.05 ± 0.65 vs 1.00 ± 0.00, 2.16 ± 0.69 vs 0.95 ± 0.21, 1.98 ± 0.56 vs 0.90 ± 0.22; 1.96 ± 0.15 vs 1.00 ± 0.00, 1.40 ± 0.14 vs 1.07 ± 0.12, 1.77 ± 0.17 vs 1.15 ± 0.21 respectively); the apoptotic index(%) of hepatocytes was higher at Day 1, 4, 7, 14 post-burn (27.20 ± 3.63 vs 5.00 ± 0.71, 16.40 ± 1.52 vs 5.40 ± 1.14, 27.60 ± 1.82 vs 7.40 ± 1.14, 10.20 ± 1.92 vs 5.20 ± 1.64 respectively). All results were statistically significant (all P < 0.05). ERS activates and expressions of associated proteins GRP78, CHOP, active caspase-12 and active caspase-3 increase in livers of severely burned rats.

Association of Heat Production with 18F-FDG Accumulation in Murine Brown Adipose Tissue After Stress

Previous studies have demonstrated that cold stress results in increased accumulation of (18)F-FDG in brown adipose tissue (BAT). Although it has been assumed that this effect is associated with increased thermogenesis by BAT, direct measurements of this phenomenon have not been reported. In the current investigation, we evaluated the relationship between stimulation of (18)F-FDG accumulation in BAT by 3 stressors and heat production measured in vivo by thermal imaging. Male SKH-1 hairless mice were subjected to full-thickness thermal injury (30% of total body surface area), cold stress (4°C for 24 h), or cutaneous wounds. Groups of 6 animals with each treatment were kept fasting overnight and injected with (18)F-FDG. Sixty minutes after injection, the mice were sacrificed, and biodistribution was measured. Other groups of 6 animals subjected to the 3 stressors were studied by thermal imaging, and the difference in temperature between BAT and adjacent tissue was recorded (ΔT). Additional groups of 6 animals were studied by both thermal imaging and (18)F-FDG biodistribution in the same animals. Accumulation of (18)F-FDG in BAT was significantly (P < 0.0001) increased by all 3 treatments (burn, ∼5-fold; cold, ∼15-fold; and cutaneous wound, ∼15-fold), whereas accumulation by adjacent white adipose tissue was unchanged. Compared with sham control mice, in animals exposed to all 3 stressors, ΔTs showed significant (P < 0.001) increases. The ΔT between stressor groups was not significant; however, there was a highly significant linear correlation (r(2) = 0.835, P < 0.0001) between the ΔT measured in BAT versus adjacent tissue and (18)F-FDG accumulation. These results establish, for the first time to our knowledge, that changes in BAT temperature determined in vivo by thermal imaging parallel increases in (18)F-FDG accumulation.

Die Behandlung der brandverletzten Hand

Although burn injuries of the hand only account for approximately 2.5-3% of the total body surface area (TBSA), they are of great importance due to functional outcome, appearance and economic aspects. Initial treatment and diagnosis are important factors, which influence the further course of thermal injuries of the hand and which are found in up to 80% of treated burn injuries. Early decision-making is necessary if escharotomy or skin grafting is indicated. After preliminary evaluation and wound management a differentiation between non-surgical and surgical procedures is necessary. In the case of full thickness thermal injuries, debridement and skin grafting should be carried out. Further interdisciplinary management involves different professional groups as surgeons and physical therapists. Fitting pressure garments and treatment of scar formation are integral parts of the successful rehabilitation of hand burns.