Thermal Injury In Rats Research Articles

In vivo monitoring of hemoglobin derivatives in a rat thermal injury model using spectral diffuse reflectance imaging

IntroductionTo demonstrate the feasibility of our previously proposed Diffuse reflectance spectral imaging (DRSI) method for in vivo monitoring of oxygenated hemoglobin, deoxygenated hemoglobin, methemoglobin, tissue oxygen saturation, and methemoglobin saturation in a rat scald burn wound model and assess whether the method could be used for differentiating the burn depth groups in rats based on the hemoglobin parameters. MethodologySuperficial dermal burns (SDBs), deep dermal burns (DDBs), and deep burns (DBs) were induced in rat dorsal skin using a Walker–Mason method. An approach based on multiple regression analysis for spectral diffuse reflectance images aided by Monte Carlo simulations for light transport was used to quantify the hemoglobin parameters. Canonical discriminant analysis (CDA) was performed to discriminate SDB, DDB, and DB. ResultsCDA using the total hemoglobin concentration, tissue oxygen saturation, and methemoglobin saturation as the independent variables showed good performance for discriminating the SDB, DDB, and DB groups immediately after burn injury and the SDB group from the DDB and DB groups 24–72 h after burn injury. ConclusionsThe DRSI method with multiple regression analysis for quantification of oxygenated hemoglobin, deoxygenated hemoglobin, and methemoglobin proved to be reliable for monitoring these hemoglobin derivatives in the rat experimental burn injury model. The parameters of tissue oxygen saturation, methemoglobin saturation, and total hemoglobin concentration are promising for the differentiating the degree of burn injury using CDA.

ASMq protects against early burn wound progression in rats by alleviating oxidative stress and secondary mitochondria‑associated apoptosis via the Erk/p90RSK/Bad pathway.

Burn wounds present an evolutionary progression, in which the initial wound tissue deepens and expands following thermal injury. Progressive tissue damage in the zone of stasis may worsen burn injury, which is associated with oxidative stress and secondary apoptosis, and worsen the prognosis of patients with burn wounds. The mitochondrial apoptotic pathway is involved in receiving oxidative signals and regulating tissue apoptosis. Previously, Abnormal Savda Munziq (ASMq), a natural compound of traditional Uyghur Medicine, which includes ten types of herb, has been reported to exhibit a number of effects, including anti-inflammatory, antioxidative and anti-apoptotic activities. The present study demonstrated that ASMq protected against early burn wound progression following thermal injury in rats; this effect may be mediated by its ability to attenuate oxidative stress-induced mitochondria-associated apoptosis. The present study may provide a novel therapeutic method to prevent early burn wound progression following burn injury.

CRYSTALLOGENIC PROPERTIES OF THE BLOOD SERUM OF RATS UNDER MODELING A THERMAL INJURY

Aim. To study the crystallogenic and initiating potential of biological fluids in rats under normal conditions and when modeling a contact thermal injury. Material and methods. To this end, we used our own model of contact thermal burn. This experiment involved the impact of a hot plate on the back of the animal, with the lesion area amounting to 20% of the body surface (3rd degree burn). This model of thermal injury was reproduced in 30 Wistar rats. 24 hours after the burn experiment, the animals were subjected to blood tests. Subsequently, an evaluation of the blood crystallogenic and initiating properties was performed. The range of basic substances used in teziographic tests was rather conventional and included 0.45, 0.9 and 3% sodium chloride solutions, as well as 0.1 N hydrochloric acid and sodium hydroxide solutions. The results of own and initiated crystallization of biological fluids were evaluated using the authors’ system of semi-quantitative indicators. Results. It is found that, in comparison with intact animals, micro-preparations of dried blood serum from rats after thermal trauma demonstrate a significant inhibition of both own crystallization and that initiated by various basic substances. This phenomenon is manifested in a significant decrease in the index of structural facies (in a crystalloscopic test), the main teziographic coefficient and the belt coefficient. The pathological nature of the observed shifts in the crystallogenic properties of biological fluids emphasizes a sharp increase in the degree of destruction demonstrated by the crystalline elements of the blood samples of rats in the main group. Conclusion. The conducted research shows that a model thermal injury in rats is accompanied by significant shifts in the crystallostasis of an animal organism, which are manifested in a significant change in the crystallogenic and initiating properties of the blood serum.

(371) Evaluation of Analgesia and Clotting Time of Novel Acetaminophen Analogs

Background: Acetaminophen and combinations of acetaminophen with opioids such as oxycodone are widely used in the management of mild to moderate pain. At the upper threshold of therapeutic doses, acetaminophen has a profound negative impact on coagulation that is amplified when combined with oxycodone. Kalyra Pharmaceuticals has developed novel acetaminophen analogs which lack hepatotoxicity. This study demonstrates that these novel acetaminophen analogs demonstrate analgesic activity and less interference on coagulation. These novel analogues therefore present a potentially better option for analgesia in battlefield and surgical scenarios where blood loss and blood clotting is a concern. Methods: Blood was collected in sodium citrate tubes and centrifuged at 1500G for 15 minutes two times to produce platelet poor plasma (PPP). PPP was treated with the novel analogs, acetaminophen, and oxycodone with combinations of each at both the recommended therapeutic dose and at 10X. Activated partial thromboplastin time was used to measure the amount of time needed for blood to clot. Analgesic efficacy of the analogs and acetaminophen was tested using our rat thermal injury model. Rats are tested at peak pain threshold using thermal hyperalgesia behavior by introducing a noxious stimulus to a burn injury and measuring paw withdraw latency. Results: Behavior testing showed a significant reduction in paw withdraw latency indicating the presence of thermal hyperalgesia. Paw withdraw latency increased after administration of acetaminophen analogs or oxycodone demonstrating analgesic efficacy of the new compounds. Our results also demonstrated that acetaminophen, but not the novel analogs or oxycodone, greatly prolonged clotting time. When combined with oxycodone, acetaminophen inhibited the clotting time by eight fold while the analogs had little deviation from un-treated plasma. Conclusion: These findings show that the novel acetaminophen analogs which lack liver toxicity demonstrate analgesic effect and are significantly less inhibitive of coagulation than acetaminophen and acetaminophen/oxycodone combinations.

Anti-inflammative effect of glycyrrhizin on rat thermal injury via inhibition of high-mobility group box 1 protein

AimGlycyrrhizin (Gly) has been reported as an inhibitor of extracellular HMGB1 (high-mobility group box 1 protein) cytokine's activity, and protects spinal cord, liver, heart and brain against ischemia-reperfusion-induced injury in rats. The purpose of this study was to investigate the protective effect of Gly in rat skin thermal injury model and to elucidate the underlying mechanisms. MethodsTwenty-four male Sprague-Dawley rats (200–250g) were randomly divided into control group, vehicle-treated and Gly-treated burn groups, each group contained eight animals. In the latter two groups, rats were subjected to 30% TBSA (Total Body Surface Area) full-thickness scald injury. In Gly-treated burn group, glycyrrhizin (60mg/kg) was administered intraperitoneally immediately after and at 24th hour burn; in vehicle-treated burn group, Ringer's solution (4ml/kg, as a vehicle) was administered intraperitoneally immediately after and at 24th hour burn. The animals were sacrificed at 48h after injury. Aortic blood samples were obtained to detect tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) with ELISA (Enzyme-Linked Immuno Sorbent Assay) kits. Lung, liver and kidney tissue samples were collected to determine the expression of HMGB1 mRNA and protein. HMGB1 mRNA level was semiquantitatively measured by Real-Time PCR using β-actin as an internal standard, and protein expression of HMGBI was determined by Western blot. ResultsSevere skin scald injury caused a significant increase in plasma TNF-α and IL-1β versus the control group (P<0.001) in 48h after burns. Intraperitoneal administration of Gly (60mg/kg) significantly reduced the levels of serum TNF-α and IL-1β (P<0.01). Gly treatment reduced these biochemical indices accompanied by lower level of HMGB1 protein (P<0.05) and mRNA expression (P<0.01). ConclusionThese results demonstrate that Gly possesses an anti-inflammation effect to protect the remote organs from burn-induced injury.

Anti-RAGE antibody ameliorates severe thermal injury in rats through regulating cellular immune function.

The receptor of advanced glycation end products (RAGE) participates in a variety of pathophysiological processes and inflammatory responses. The aim of this study was to investigate the therapeutic potential of an anti-RAGE neutralizing antibody for severe thermal injury in rats, and to determine whether the treatment worked via modulating cellular immune function. Full-thickness scald injury was induced in Wistar rats, which were treated with the anti-RAGE antibody (1 mg/kg, iv) at 6 h and 24 h after the injury. The rats were sacrificed on d 1, 3, 5, and 7. Blood and spleen samples were harvested to monitor organ function and to analyze dendritic cell (DC) and T cell cytokine profiles. The survival rate was analyzed up to d 7 after the injury. Administration of the antibody significantly increased the 7 d survival rate in thermally injured rats (6.67% in the model group; 33.33% in anti-RAGE group). Treatment with the antibody also attenuated the multiple organ dysfunction syndrome (MODS) following the thermal injury, as shown by significant decreases in the organ dysfunction markers, including serum ALT, AST, blood urea nitrogen, creatinine and CK-MB. Moreover, treatment with the antibody significantly promoted DC maturation and T cell activation in the spleens of thermally injured rats. Blockade of the RAGE axis by the antibody effectively ameliorated MODS and improved the survival rate in thermally injured rats, which may be due to modulation of cellular immune function.

Antinociceptive and anti-inflammatory effects of Aloe saponaria Haw on thermal injury in rats

Ethnopharmacological relevanceIn Brazil, the plant Aloe saponaria Haw, popularly known as “babosa pintadinha”, has been empirically used for its potential effect on thermal injury. Because there are no scientific data confirming its popular use, the aim of the present study was to investigate the effects of Aloe saponaria on nociceptive and inflammatory parameters in a rat model of thermal injury. Materials and methodsAdult male Wistar rats were subjected to a thermal injury or sham procedure (immersion in water at 70 or 37°C, respectively, for 5 or 8s). Burned animals were topically treated with vehicle (base cream), sulfadiazine 1% (positive control) or Aloe saponaria cream (0.3%–30%) once a day for 2 or 6 days. Each day, 30min before the treatment, we measured nociceptive (static and dynamic mechanical allodynia, thermal allodynia and spontaneous pain) and inflammatory (paw edema) parameters. Moreover, enzymatic indicators of leukocyte infiltration into burned tissue were also determined 2 or 6 days after the thermal injury. ResultsThe thermal injury (fist and second-degree) procedure, but not the sham procedure, induced nociception and inflammation from 1 to 6 days after the injury. The topical treatment with Aloe saponaria cream (10%) reduced nociceptive behaviors from day 1 to 6 (peak at day 2), edema at days 5 and 6 (peak at day 6) and myeloperoxidase, N-acetyl-glucosaminidase and eosinoperoxidase activities at day 6. The antinociceptive and anti-inflammatory effects of Aloe saponaria were obtained with doses of 3%–30%, with maximal inhibition obtained with a dose of 10% (reductions of 39±9%, 41±9%, 31±7%, 83±7% and 23±2% for static and dynamic mechanical allodynia, thermal allodynia, spontaneous pain and paw edema, respectively). ConclusionOur results demonstrate that topically applied Aloe saponaria presented antinociceptive and anti-inflammatory effects in rats subjected to a thermal injury, which supports its traditional use for burn injuries.

Melatonin modulates the expression of Bcl-2 family proteins in liver after thermal injury in rats

Melatonin, the principal secretory product of the pineal gland, functions as a potent antioxidant and free radical scavenger. Additionally, the antiapoptotic effect of melatonin has been observed both in vivo and in vitro. The aim of this study was to investigate the protective effects of melatonin against burn-induced injury in rat liver and whether these changes were associated with oxidative stress and changes in the expression of apoptosis related genes Bcl-2 and Bax. Melatonin (10 mg/kg, i.p.) was applied immediately after 30% of total body surface area (TBSA) burns of male Wistar rats. Malondialdehyde (MDA) as marker of oxidative stress and tumor necrosis factor (TNF-α) as inflammatory marker were assayed by biochemical methods. The hepatic apoptosis related genes Bcl-2 and Bax using light immunоchistochemistry were investigated, too. Hepatic TNF-α and MDA levels were increased significantly following severe burn. Thermal trauma increased the Bax expression without any changes of anti-apoptotic Bcl-2 protein in sinusoidal endothelial cells (SECs) of burn-treated animals compared with the control group animals as well as elevated ratio Bax/Bcl-2 suggesting the susceptibility of these cells to apoptosis. Melatonin significantly decreased the MDA and TNF-α levels in the liver tissue. It decreased also expression of Bax, increased expression of Bcl-2 and reduced Bax/Bcl-2 ratio. In conclusion, experimental data show that melatonin modulates the expression of Bcl-2 family proteins by increasing anti-apoptotic Bcl-2, inhibits apoptosis and restricts the burn-induced damage.

17β-Estradiol reappropriates mass lost to the hypermetabolic state in thermally injured rats

BackgroundThe hypermetabolic response to severe thermal injury is unlike any physiologic response seen in medicine. While some parallels can be drawn to shock and sepsis states, this response is typified by its intensity and duration. Our group has been interested in the myriad effects of estrogens after injury, specifically the ability of estrogens to reduce inflammatory responses. Given this, and the known link between severe inflammation and the hypermetabolic response, we examined the effects of a single dose of 17β estradiol administered after a severe thermal injury in rats. MethodsTwelve male Sprague-Dawley rats were subject to either a sham burn or a 40% total body surface area burn, followed by fluid resuscitation. Burned animals were divided into a vehicle and treatment group, with injections given 15 min after the injury. Animals were monitored for a period of 45 d, with markers of hypermetabolism (weight, fecal output, food intake, and serum insulin and glucose) measured daily. ResultsWe identified a significant difference in daily measured weights between the burned groups. We observed a sparing of body mass during the acute phase lasting 2 wk after the injury and an improved recovery phase during the remainder of the study. Glucose and insulin levels during the first week of the study did not differ between the treatment groups. ConclusionEstrogen may have a role in preserving body mass after severe thermal injury. Further studies are required to determine if this spared body mass composition.

Role of tumor necrosis factor–α and matrix metalloproteinase–9 in blood-brain barrier disruption after peripheral thermal injury in rats: Laboratory investigation

Role of tumor necrosis factor–α and matrix metalloproteinase–9 in blood-brain barrier disruption after peripheral thermal injury in rats: Laboratory investigation

Melatonin Plays a Protective Role in Postburn Rodent Gut Pathophysiology

Melatonin is a possible protective agent in postburn gut pathophysiological dynamics. We investigated the role of endogenously-produced versus exogenously-administered melatonin in a major thermal injury rat model with well-characterized gut inflammatory complications. Our rationale is that understanding in vivo melatonin mechanisms in control and inflamed tissues will improve our understanding of its potential as a safe anti-inflammatory/antioxidant therapeutic alternative. Towards this end, we tested the hypothesis that the gut is both a source and a target for melatonin and that mesenteric melatonin plays an anti-inflammatory role following major thermal injury in rats with 3rd degree hot water scald over 30% TBSA. Our methods for assessing the gut as a source of melatonin included plasma melatonin ELISA measurements in systemic and mesenteric circulation as well as rtPCR measurement of jejunum and terminal ileum expression of the melatonin synthesizing enzymes arylalkylamine N-acetyltransferase (AA-NAT) and 5-hydroxyindole-O-methyltransferase (HIOMT) in sham versus day-3 postburn rats. Our melatonin ELISA results revealed that mesenteric circulation has much higher melatonin than systemic circulation and that both mesenteric and systemic melatonin levels are increased three days following major thermal injury. Our rtPCR results complemented the ELISA data in showing that the melatonin synthesizing enzymes AA-NAT and HIOMT are expressed in the ileum and jejunum and that this expression is increased three days following major thermal injury. Interestingly, the rtPCR data also revealed negative feedback by melatonin as exogenous melatonin supplementation at a dose of 7.43 mg (32 micromole/kg), but not 1.86 mg/kg (8 micromole/kg) drastically suppressed AA-NAT mRNA expression. Our methods also included an assessment of the gut as a target for melatonin utilizing computerized immunohistochemical measurements to quantify the effects of exogenous melatonin supplementation on postburn gut mucosa barrier inflammatory profiles. Here, our results revealed that daily postburn intraperitoneal melatonin administration at a dose of 1.86 mg/kg (8 micromole/kg) significantly suppressed both neutrophil infiltration and tyrosine nitrosylation as revealed by Gr-1 and nitrotyrosine immunohistochemistry, respectively. In conclusion, our results provide support for high mesenteric melatonin levels and dynamic de novo gut melatonin production, both of which increase endogenously in response to major thermal injury, but appear to fall short of abrogating the excessive postburn hyper-inflammation. Moreover, supplementation by exogenous melatonin significantly suppresses gut inflammation, thus confirming that melatonin is protective against postburn inflammation.

Effect of vagus nerve stimulation on thermal injury in rats

Objective To investigate the effects of vagus nerve stimulation on haemodynamics, pulmonary histopathology, arterial blood gas and pro-inflammatory responses to thermal injury. Interventions Forty-eight male Sprague–Dawley (SD) rats were randomly divided into six equal groups: normal control (NC) group; thermal injury (TEM) group subjected to 40% total body surface area (%TBSA) third-degree thermal injury; vagotomy (VGX) group subjected to bilateral cervical vagotomy after thermal injury; electrical stimulation (STM) group subjected to bilateral cervical vagotomy plus the left vagus nerve trunk electrical stimulation (5 V, 2 ms and 1 Hz) after thermal injury; the antagonist of muscarinic acetylcholine receptor (MRA) group administrated with atropine (0.1 mg kg −1) before electrical stimulation and the antagonist of nicotinic acetylcholine receptor (NRA) group administrated with hexamethonium (10 mg kg −1) before electrical stimulation. Measurements and main results The haemodynamics, histopathology of lung tissue, arterial blood gas, lactic acid, tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were measured. Vagus nerve electrical stimulation not only significantly increased the mean arterial pressure (MAP) and heart rate (HR), but also decreased the infiltration of inflammatory cells into interstitial and alveolar spaces after thermal challenge and attenuated TNF-α and IL-6 production. Hexamethonium pre-treatment significantly reversed the effects of vagal electrical stimulation, but atropine administration before electrical stimulation had no such effects. Conclusions Direct electrical stimulation of the vagus nerve might produce therapeutic effect on thermal injury. The effect may be realised by limiting the inflammatory response via nicotinic acetylcholine receptors in rats.

Role of tumor necrosis factor–α and matrix metalloproteinase–9 in blood-brain barrier disruption after peripheral thermal injury in rats

A relationship has been found between peripheral thermal injury and cerebral complications leading to injury and death. In the present study, the authors examined whether tumor necrosis factor-alpha (TNF-alpha) and matrix metalloproteinase-9 (MMP-9) play a causative role in blood-brain barrier (BBB) disruption after peripheral thermal injury. Thirty-two male Sprague-Dawley rats were subjected to thermal injury. One hour later, 8 rats were injected with TNF-alpha neutralizing antibody, and 8 were injected with doxycycline, an inhibitor of the MMP family proteins; 16 rats did not receive any treatment. Brain tissue samples obtained 7 hours after injury in the treated animals were examined for BBB function by using fluorescein isothiocyanate-dextran and by assessing parenchymal water content. Protein expression of basement membrane components (collagen IV, laminin, and fibronectin) was quantified on Western blot analysis, and MMP-9 protein expression and enzyme activity were determined using Western blot and gelatin zymography. Thermally injured rats that did not receive treatment were killed at 3, 7, or 24 hours after injury and tested for BBB functioning at each time point. Histological analysis for basement membrane proteins was also conducted in untreated rats killed at 7 hours after injury. Results of testing in injured rats were compared with those obtained in a control group of rats that did not undergo thermal injury. At 7 hours after thermal injury, a significant increase in the fluorescein isothiocyanate-dextran and water content of the brain was found (p < 0.05), but BBB dysfunction was significantly decreased in the rats that received TNF-alpha antibody or doxycycline (p < 0.05). In addition, the components of the basal lamina were significantly decreased at 7 hours after thermal injury (p < 0.01), and there were significant increases in MMP-9 protein expression and enzyme activity (p < 0.05). The basal lamina damage was reversed by inhibition of TNF-alpha and MMP-9, and the increase in MMP-9 protein was reduced in the presence of doxycycline (p < 0.05). The authors found that MMP-9 enzyme activity was significantly increased after thermal injury (p < 0.01) but decreased in the presence of either TNF-alpha antibody or doxycycline (p < 0.01). The dual, inhibitory activity of both TNF-alpha and MMP-9 in brain injury suggests that a TNF-alpha and MMP-9 cascade may play a key role in BBB disruption. These results offer a better understanding of the pathophysiology of burn injuries, which may open new avenues for burn treatment beyond the level of current therapies.

Intestinal Dipeptide Absorption Is Preserved During Thermal Injury and Cytokine Treatment

Intestinal barrier function is impaired during thermal injury; however, the effects of thermal injury on the absorption of dietary peptides are not well characterized. The purpose of this study was to determine the impact of thermal injury on dipeptide absorption in rats and to describe the influence of inflammatory cytokines on the expression of the oligopeptide transporter PEPT1 and dipeptide permeability in cultured intestinal cells (Caco-2 cells). Sprague Dawley rats were assigned to 30% body surface area burn (n = 7) or sham (n = 8) groups. Twenty-four hours following burn/sham, the proximal jejunum was cannulated. The jejunal segment was perfused with buffer containing the dipeptide glycylsarcosine (Gly-Sar), and intestinal permeability (P(eff)) was calculated. For in vitro experiments, Caco-2 cells were grown on permeable supports and treated with tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-10 (10 ng/mL) alone and in combination for 48 hours. The effective apical-to-basolateral permeabilities (P(eff)) of Gly-Sar were measured, and PEPT1 expression was determined using reverse transcription-polymerase chain reaction. Gly-Sar P(eff) was similar in burn and sham rats (6.67 +/- 2.27 x 10(-5) vs 7.58 +/- 2.20 x 10(-5) cm/s, respectively, P = .45). In Caco-2 cells, cytokine treatment did not alter PEPT1 expression (P = .954) or the P(eff) of Gly-Sar (P = .806). Intestinal absorption of the dipeptide Gly-Sar is preserved 24 hours following thermal injury in rats. Likewise, PEPT1 expression and peptide absorption are preserved following treatment with TNF-alpha, IL-6, and IL-10 in Caco-2 monolayers. These findings imply that intestinal dipeptide absorption may be preserved during burn injury. This may lead to new strategies to optimize enteral protein delivery in burn patients.

Preliminary study of skeletal muscle apoptosis after severe thermal injury in rats

To investigate changes in skeletal muscle apoptosis after a severe thermal injury in rats. One hundred Wistar rats were randomly divided into two groups: sham thermal injury group and severe thermal injury group. They were subdivided into 1, 4, 7, 10, 14 days post-injury with 10 rats in each subgroup. Rats in severe thermal injury group were subjected to a 40% total body surface area full-thickness scald injury. Both weight and tibialis anterior (TA) mass of rats were weighed on 1, 4, 7, 10, 14 days post-injury. Electron microscope was used for observing ultrastructural changes in skeletal muscle, including apoptosis. Tissues of tibialis anterior from burn and sham burn animals were then examined by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and immunohistochemistry. Compared with sham thermal injury group, body weight and TA mass of rats were decreased from first day on, and it dropped to the lowest level at 4 days (P<0.05 and P<0.01), and started to regain from 7 days on (all P<0.01). Electron micrographs showed condensation of chromatin around the periphery of the nucleus, blebbing of the sarcolemma, and free of myofibrils near myonuclei in a large area in skeletal muscle of thermally injured rats. Sporadic TUNEL positive myonuclei were also seen under light microscope in skeletal muscle in thermal injury group. There were no characteristic signs of apoptosis in skeletal muscle in rats of sham group. There are skeletal muscle apoptosis after severe thermal injury. It may contribute to atrophy of skeletal muscle after burn injury in rats.

Maté attenuates DNA damage and carcinogenesis induced by diethylnitrosamine and thermal injury in rat esophagus

Drinking hot maté has been associated with risk for esophageal cancer in South America. Thus, the aims of this study were to evaluate the modifying effects of maté intake on DNA damage and esophageal carcinogenesis induced by diethylnitrosamine (DEN) and thermal injury (TI) in male Wistar rats. At the initiation phase of carcinogenesis, rats were treated with DEN (8 × 80 mg/kg) and submitted to TI (water at 65 °C, 1 ml/rat, instilled into the esophagus). Concomitantly, the animals received maté (2.0% w/v) for 8 weeks. Samples of peripheral blood were collected 4 h after the last DEN application for DNA damage analysis. At weeks 8 and 20, samples from esophagus and liver were also collected for histological and immunohistochemical analysis. Maté significantly decreased DNA damage in leukocytes, cell proliferation rates in both esophagus and liver and the number of preneoplastic liver lesions from DEN/TI-treated animals at week 8. A significant lower incidence of esophageal papillomas and liver adenomas and tumor multiplicity was observed in the animals previously treated with maté at week 20. Thus, maté presented protective effects against DNA damage and esophageal and liver carcinogenesis induced by DEN.

Peripheral thermal injury causes early blood–brain barrier dysfunction and matrix metalloproteinase expression in rat

High mortality incidence after serious systemic thermal injury is believed to be linked to significant increases in cerebral permeability, ultimately leading to irreversible blood–brain barrier (BBB) breakdown. The aim of this study was to investigate whether disruption of microvascular integrity in a rat thermal injury model is associated with early matrix metalloproteinase (MMP) expression.A total of 35 Sprague–Dawley rats were studied in thermal injury and control groups, each group containing two subgroups, one for brain edema and Evans blue analysis and another for MMP mRNA analysis. Thermally injured animals were anesthetized and submerged vertically in 85°C water to the neck for 6 seconds producing a third degree burn affecting 70% of the total body surface area. BBB integrity was determined by measuring amount of Evans blue after 7 hours of injury with a spectrophotometer. Brain edema was detected by calculating water content. Brain mRNA levels were determined with real-time PCR 3 and 7 hours post-injury.Brain water content was significantly increased after peripheral injury at hour 7. Evans blue leakage was also significantly increased at the same time, suggesting an impaired BBB function after injury. Expressions of MMP-2 and MMP-9 mRNA in brain were increased as early as 3 hours after injury and remained at hour 7.Our study demonstrated a significant increase in cerebral permeability that occurs after serious systemic thermal injury. The underlying mechanisms could be related to early expression of MMPs.

Bioinformatics analysis of the early inflammatory response in a rat thermal injury model.

BackgroundThermal injury is among the most severe forms of trauma and its effects are both local and systemic. Response to thermal injury includes cellular protection mechanisms, inflammation, hypermetabolism, prolonged catabolism, organ dysfunction and immuno-suppression. It has been hypothesized that gene expression patterns in the liver will change with severe burns, thus reflecting the role the liver plays in the response to burn injury. Characterizing the molecular fingerprint (i.e., expression profile) of the inflammatory response resulting from burns may help elucidate the activated mechanisms and suggest new therapeutic intervention. In this paper we propose a novel integrated framework for analyzing time-series transcriptional data, with emphasis on the burn-induced response within the context of the rat animal model. Our analysis robustly identifies critical expression motifs, indicative of the dynamic evolution of the inflammatory response and we further propose a putative reconstruction of the associated transcription factor activities.ResultsImplementation of our algorithm on data obtained from an animal (rat) burn injury study identified 281 genes corresponding to 4 unique profiles. Enrichment evaluation upon both gene ontologies and transcription factors, verifies the inflammation-specific character of the selections and the rationalization of the burn-induced inflammatory response. Conducting the transcription network reconstruction and analysis, we have identified transcription factors, including AHR, Octamer Binding Proteins, Kruppel-like Factors, and cell cycle regulators as being highly important to an organism's response to burn response. These transcription factors are notable due to their roles in pathways that play a part in the gross physiological response to burn such as changes in the immune response and inflammation.ConclusionOur results indicate that our novel selection/classification algorithm has been successful in selecting out genes with play an important role in thermal injury. Additionally, we have demonstrated the value of an integrative approach in identifying possible points of intervention, namely the activation of certain transcription factors that govern the organism's response.

Peripheral thermal injury causes blood–brain barrier dysfunction and matrix metalloproteinase (MMP) expression in rat

Mortality after serious systemic thermal injury may be linked to significant increases in cerebral vascular permeability and edema due to blood–brain barrier (BBB) breakdown. This BBB disruption is thought to be mediated by a family of proteolytic enzymes known as matrix metalloproteinases (MMPs). The gelatinases, MMP-2 and MMP-9, digest the endothelial basal lamina of the BBB, which is essential for maintaining BBB integrity. The current study investigated whether disruption of microvascular integrity in a rat thermal injury model is associated with gelatinase expression and activity. Seventy-two adult Sprague-Dawley rats were anesthetized and submerged horizontally, in the supine position, in 100 °C (37 °C for controls) water for 6 s producing a third-degree burn affecting 60–70% of the total body surface area. Brain edema was detected by calculating water content. Real time PCR, Western blot, and zymography were used to quantify MMP mRNA, protein, and enzyme activity levels. Each group was quantified at 3, 7, 24, and 72 h post thermal injury. Brain water content was significantly increased 7 through 72 h after burn. Expression of brain MMP-9 mRNA was significantly increased as early as 3 h after thermal injury compared to controls, remained at 7 h ( p < 0.01), and returned to control levels by 24 h. MMP-9 protein levels and enzyme activity began to increase at 7 h and reached significant levels between 7 and 24 h after thermal injury. While MMP-9 protein levels continued to increase significantly through 72 h, enzyme activity returned to control level. The increase in MMP-9 expression and activity, associated with increased BBB permeability following thermal injury, indicates that MMP-9 may contribute to observed cerebral edema in peripheral thermal injury.

The Role of Bifidobacteria in Gut Barrier Function After Thermal Injury in Rats

Early multiple organ dysfunction syndrome appears to be facilitated with bacterial translocation in severe burn injury, yet the mechanisms of bacterial translocation remain in dispute. The aim of this study was to characterize the potential role of intestinal bifidobacteria in the pathogenesis of gut-derived bacterial translocation after burns and to analyze the effects of bifidobacterial supplement on gut barrier function. Wistar rats were randomly divided into burn group (Burn, n = 60), sham burn group (SB, n = 10) in experiment 1, and burn + saline group (BS, n = 30), burn + bifidobacteria group (BB, n = 30), and sham-burn + saline group (SS, n = 30) in experiment 2. Animals in BB group were fed bifidobacterial preparation (5 x 10(9) CFU/mL) after burns, 1.5 mL, twice daily. Animals in BS and SS were fed saline. Samples were taken on postburn days 1, 3, and 5. The incidence of bacterial translocation and counts of Bifidobacterium, fungi and Escherichia coli in gut mucosa, as well as the sIgA levels in mucus of the small intestine were determined. The positive sIgA expression in lamina propria and ileum mucosal injury were evaluated light microscopically by blinded examiners. The incidence of bacterial translocation was increased after burns, which was accompanied by significant decrease in number of bifidobacteria but significant increase in E. coli and fungi in gut mucosa, and elevation of levels of plasma endotoxin and IL-6 (p < 0.001). The incidence of bacterial translocation was markedly reduced after 3- and 5-day supplementation of bifidobacteria compared with control group (p < 0.05). The counts of mucosal bifidobacteria were increased by 4- to 40-fold, whereas E. coli and fungi were decreased by 2- to 30-fold and 10- to 150-fold, respectively, after bifidobacterial supplementation. The damage of mucosa tended to be less pronounced after 3-day bifidobacteria-supplemented formula compared with control group (grade 2 [0-6] versus grade 4 [3-6], p < 0.05). Moreover, the expression and release of sIgA was markedly augmented after 3-days of bifidobacteria-supplementation formula and it returned to normal range on postburn day 5. The decrease in counts and proportion of bifidobacteria to other flora in gut may play an important role in the development of bacterial translocation after thermal injury. Supplementation of exogenous bifidobacteria could improve gut barrier function, and attenuate bacterial/endotoxin translocation secondary to major burns.