Insulin increases resistance to burn wound infection-associated sepsis

Lung Protection After Severe Thermal Burns With Adenosine, Lidocaine, and Magnesium (ALM) Resuscitation and Importance of Shams in a Rat Model

The management of severe burns remains a complex challenge. Adenosine, lidocaine, and magnesium (ALM) resuscitation therapy has been shown to protect against hemorrhagic shock and traumatic injury. The aim of the present study was to investigate the early protective effects of small-volume ALM fluid resuscitation in a rat model of 30% total body surface area (TBSA) thermal injury. Male Sprague-Dawley rats (320-340 g; n = 25) were randomly assigned to: 1) Sham (surgical instrumentation and saline infusion, without burn, n = 5), 2) Saline resuscitation group (n = 10), or 3) ALM resuscitation group (n = 10). Treatments were initiated 15-min after burn trauma, including 0.7 mL/kg 3% NaCl ± ALM bolus and 0.25-0.5 mL/kg/h 0.9% NaCl ± ALM drip, with animals monitored to 8.25-hr post-burn. Hemodynamics, cardiac function, blood chemistry, hematology, endothelial injury markers and histopathology were assessed. Survival was 100% for Shams and 90% for both ALM and Saline groups. Shams underwent significant physiological, immune and hematological changes over time as a result of surgical traums. ALM significantly reduced malondialdehyde levels in the lungs compared to Saline (P = .023), and showed minimal alveolar destruction and inflammatory cell infiltration (P < .001). ALM also improved cardiac function and oxygen delivery (21%, P = .418 vs Saline), reduced gut injury (P < .001 vs Saline), and increased plasma adiponectin (P < .001 vs baseline). Circulating levels of the acute phase protein alpha 1-acid glycoprotein (AGP) increased 1.6-times (P < .001), which may have impacted ALM's therapeutic efficacy. We conclude that small-volume ALM therapy significantly reduced lung oxidative stress and preserved alveolar integrity following severe burn trauma. Further studies are required to assess higher ALM doses with longer monitoring periods.

Insulin Regulation of Escherichia coli Abiotic Biofilm Formation: Effect of Nutrients and Growth Conditions

Escherichia coli plays an important role in biofilm formation across a wide array of disease and ecological settings. Insulin can function as an adjuvant in the regulation of biofilm levels. The modulation of insulin-regulated biofilm formation by environmental conditions has not been previously described. In the present study, the effects that various environmental growth conditions and nutrients have on insulin-modulated levels of biofilm production were measured. Micropipette tips were incubated with E. coli ATCC^® 25922™ in a Mueller Hinton broth (MH), or a yeast nitrogen base with 1% peptone (YNBP), which was supplemented with glucose, lactose, galactose and/or insulin (Humulin^®-R). The incubation conditions included a shaking or static culture, at 23 °C or 37 °C. After incubation, the biofilm production was calculated per CFU. At 23 °C, the presence of insulin increased biofilm formation. The amount of biofilm formation was highest in glucose > galactose >> lactose, while the biofilm levels decreased in shaking cultures, except for galactose (3-fold increase; 0.1% galactose and 20 μU insulin). At 37 °C, regardless of condition, there was more biofilm formation/CFU under static conditions in YNBP than in MH, except for the MH containing galactose. E. coli biofilm formation is influenced by aeration, temperature, and insulin concentration in combination with the available sugars.

Evaluation of the use of sitagliptin for insulin resistance in burn patients

BACKGROUND

Following severe burn injury, patients undergo profound metabolic changes, including insulin resistance and hyperglycemia. Hyperglycemia has been linked to impaired wound healing, increased risk of skin graft loss, increased muscle catabolism, increased infections, and mortality. Sitagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that improves glycemic control by slowing the inactivation of incretin hormones, increasing insulin synthesis and release from pancreatic beta cells and lowering glucagon secretion from pancreatic alpha cells. The objective of this study was to describe our institution's experience with using sitagliptin to help mitigate insulin resistance after burn injury.

METHODS

This was a retrospective chart review that included 22 adult burn patients. Burn patients were prescribed sitagliptin regardless of their previous medical history of type 2 diabetes mellitus. Patients were included in this analysis if they were adults admitted for burn injury during a 13-month period and received at least 3 consecutive doses of sitagliptin. Patients were excluded if they did not have insulin use data 3 days pre- and 3 days post-sitagliptin initiation. The first day of sitagliptin initiation was considered day 0; data from day 0 were not included in either the pre- or post-sitagliptin analysis.

RESULTS

In the 3 days prior to sitagliptin initiation, patients received a median of 114.3 units per day (IQR 49.1, 228) in an attempt to maintain a blood glucose goal of less than 180 mg/dL. In the 3 days after sitagliptin was started, exogenous insulin requirements significantly decreased to a median to 36.3 units per day (IQR 11.7, 95) (P=0.009). Seven patients were on insulin infusions at the time of sitagliptin initiation. After sitagliptin was started, it took a median of 3 days (IQR 2, 3.25) to be liberated from the insulin infusion. In terms of safety, there were two episodes of hypoglycemia (BG<70 mg/dL) after sitagliptin initiation, compared to three episodes prior to sitagliptin initiation (P=0.7).

CONCLUSION

The addition of sitagliptin to burn patients' medication regimens significantly reduced insulin requirements over a 3-day period and allowed liberation from insulin drips.

Insulin treatment enhances pseudomonas aeruginosa biofilm formation by increasing intracellular cyclic di-GMP levels, leading to chronic wound infection and delayed wound healing

Diabetes-related infections have become challenging and important public health problems in China and around the world. P. aeruginosa plays an important role in diabetic foot infections. As a gram-negative opportunistic pathogen, P. aeruginosa causes recurrent and refractory infections that are characterized by biofilm formation. Previous studies have demonstrated that biofilm-challenged wounds typically take longer to heal than non-biofilm-challenged normal wounds in diabetic mouse models. In the present study, we sought to explore the mechanism via which insulin treatment affects cyclic di-GMP signaling in P. aeruginosa-infected chronic wounds in db/db diabetic mice. We found that the wounds of diabetic mice healed more slowly than those of nondiabetic mice. Moreover, wound healing in diabetic mice treated with insulin exhibited a considerable delay. Peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH) was used to detect biofilms on P. aeruginosa-infected wound tissues. Increased intracellular c-di-GMP levels promoted biofilm formation in wound tissues from nondiabetic mice. Greater biofilm formation was observed in the wounds of insulin-treated diabetic mice than in the wounds of untreated diabetic mice or nondiabetic mice, in both the PAO1/p_lac-yhjH- and PAO1-infected groups. Quantitative RT-PCR indicated that upon infection with PAO1/P_lac-yhjH (the low c-di-GMP expression strain), the expression of IL-4 RNA was significantly higher in diabetic mice treated with insulin than in untreated diabetic mice or nondiabetic mice at each observation time point. Peak expression of IFN-γ occurred earlier in diabetic mice treated with insulin than in untreated diabetic mice with each of the experimental strains. Finally, P. aeruginosa harboring the plasmid pCdrA: gfp ^s was used as a reporter strain to monitor c-di-GMP levels. We found that insulin could promote biofilm formation by increasing intracellular c-di-GMP levels in vitro. Taken together, these data demonstrate that insulin treatment increases intracellular c-di-GMP levels, promotes biofilm formation and prolongs the inflammation period during the healing of infected wounds, resulting in delayed wound healing.

Insulin Resistance in Macrophages Alters Their Metabolism and Promotes an M2-Like Phenotype

Obesity and insulin resistance influences metabolic processes, but whether it affects macrophage metabolism is not known. In this study, we demonstrate that chronic exposure of macrophages to insulin either in culture or in vivo in diet-induced, glucose-intolerant mice rendered them resistant to insulin signals marked by failure to induce Akt2 phosphorylation. Similarly, macrophages lacking Akt2 or IGF1 receptor were also resistant to insulin signals. Insulin-resistant macrophages had increased basal mTORC1 activity, possessed an M2-like phenotype, and reduced LPS responses. Moreover, they exhibited increased glycolysis and increased expression of key glycolytic enzymes. Inhibition of mTORC1 reversed the M2-like phenotype and suppressed glycolysis in insulin-resistant macrophages. In the context of polymicrobial sepsis, mice harboring insulin-resistant macrophages exhibited reduced sepsis-induced lung injury. Thus, macrophages obtain resistance to insulin characterized by increased glycolysis and a unique M2-like phenotype, termed M-insulin resistant, which accounts for obesity-related changes in macrophage responses and a state of trained immunity.

IL-6 Signal From the Bone Marrow is Required for the Browning of White Adipose Tissue Post Burn Injury

The hypermetabolic stress response after burn contributes to multi-organ failure, sepsis, morbidity, and mortality. The cytokine interleukin 6 (IL-6) has been hypothesized to mediate not only white adipose tissue (WAT) browning in burns, but also other hypermetabolic conditions. In addition to its inflammatory effects, IL-6 also acts as a metabolic mediator that affects metabolic tissues. Therefore, we sought to uncover the origin of circulating IL-6 post burn injury that regulates WAT browning. WAT and sera samples were collected from both adult burn patients admitted to the Ross Tilley Burn Centre at Sunnybrook Hospital and mice subjected to a burn injury. Collected tissues were analyzed for browning markers and metabolic state via histology, gene expression, and resting energy expenditure. Increased WAT browning was observed in burn patients as well as mice subjected to burn injury. Circulating IL-6 levels were significantly elevated post burn injury in mice (<0.05) and in burn patients (<0.05), the latter of which was positively correlated with elevated REE. Genetic loss of whole body IL-6 in mice prevented burn-induced WAT browning. Transplanting IL-6 knockout (KO) mice with bone marrow (BM) from wild-type (WT) mice, recovered the browning phenotype in these mice, as evaluated by increased uncoupling protein 1 (UCP1) expression (<0.05). Conversely, transplanting irradiated WT mice with BM from IL-6 KO mice impaired burn induced browning with no significant expression of UCP1. Together, our findings implicate BM derived IL-6 as the source controlling browning of WAT post burn injury. Thus, targeting IL-6 is a promising target for hypermetabolism in burns.

Specific Etiologies Associated With the Multiple Organ Dysfunction Syndrome in Children: Part 2

OBJECTIVE

To describe a number of conditions and therapies associated with multiple organ dysfunction syndrome presented as part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Multiple Organ Dysfunction Workshop (March 26-27, 2015). In addition, the relationship between burn injuries and multiple organ dysfunction syndrome is also included although it was not discussed at the workshop.

DATA SOURCES

Literature review, research data, and expert opinion.

STUDY SELECTION

Not applicable.

DATA EXTRACTION

Moderated by an expert from the field, issues relevant to the association of multiple organ dysfunction syndrome with a variety of conditions and therapies were presented, discussed, and debated with a focus on identifying knowledge gaps and the research priorities.

DATA SYNTHESIS

Summary of presentations and discussion supported and supplemented by relevant literature.

CONCLUSIONS

Sepsis and trauma are the two conditions most commonly associated with multiple organ dysfunction syndrome both in children and adults. However, many other pathophysiologic processes may result in multiple organ dysfunction syndrome. In this article, we discuss conditions such as liver failure and pancreatitis, pathophysiologic processes such as ischemia and hypoxia, and injuries such as trauma and burns. Additionally, therapeutic interventions such as medications, blood transfusions, transplantation may also precipitate and contribute to multiple organ dysfunction syndrome. The purpose of this article is to describe the association of multiple organ dysfunction syndrome with a variety of conditions and therapies in an attempt to identify similarities, differences, and opportunities for therapeutic intervention.

Postburn Hypermetabolism: Past, Present, and Future

Hypermetabolism is the ubiquitous response to a severe burn injury, which was first described in the nineteenth century. Despite identification of important components of this complex response, hypermetabolism is still not well understood in its entirety. This article describes this incredibly fascinating response and the understanding we have gained over the past 100 years. Additionally, this article describes novel insights and delineates treatment options to modulate postburn hypermetabolism with the goal to improve outcomes of burn patients.

Cardiovascular Dysfunction Following Burn Injury: What We Have Learned from Rat and Mouse Models

Severe burn profoundly affects organs both proximal and distal to the actual burn site. Cardiovascular dysfunction is a well-documented phenomenon that increases morbidity and mortality following a massive thermal trauma. Beginning immediately post-burn, during the ebb phase, cardiac function is severely depressed. By 48 h post-injury, cardiac function rebounds and the post-burn myocardium becomes tachycardic and hyperinflammatory. While current clinical trials are investigating a variety of drugs targeted at reducing aspects of the post-burn hypermetabolic response such as heart rate and cardiac work, there is still a paucity of knowledge regarding the underlying mechanisms that induce cardiac dysfunction in the severely burned. There are many animal models of burn injury, from rodents, to sheep or swine, but the majority of burn related cardiovascular investigations have occurred in rat and mouse models. This literature review consolidates the data supporting the prevalent role that β-adrenergic receptors play in mediating post-burn cardiac dysfunction and the idea that pharmacological modulation of this receptor family is a viable therapeutic target for resolving burn-induced cardiac deficits.

Pathophysiologic Response to Burns in the Elderly

Over the last decades advancements have improved survival and outcomes of severely burned patients except one population, elderly. The Lethal Dose 50 (LD50) burn size in elderly has remained the same over the past three decades, and so has morbidity and mortality, despite the increased demand for elderly burn care. The objective of this study is to gain insights on why elderly burn patients have had such a poor outcome when compared to adult burn patients. The significance of this project is that to this date, burn care providers recognize the extreme poor outcome of elderly, but the reason remains unclear. In this prospective translational trial, we have determined clinical, metabolic, inflammatory, immune, and skin healing aspects. We found that elderly have a profound increased mortality, more premorbid conditions, and stay at the hospital for longer, p < 0.05. Interestingly, we could not find a higher incidence of infection or sepsis in elderly, p > 0.05, but a significant increased incidence of multi organ failure, p < 0.05. These clinical outcomes were associated with a delayed hypermetabolic response, increased hyperglycemic and hyperlipidemic responses, inversed inflammatory response, immune-compromisation and substantial delay in wound healing predominantly due to alteration in characteristics of progenitor cells, p < 0.05. In summary, elderly have substantially different responses to burns when compared to adults associated with increased morbidity and mortality. This study indicates that these responses are complex and not linear, requiring a multi-modal approach to improve the outcome of severely burned elderly.

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The outcome of elderly burn management is low with reasons that remain unclear.

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Elderly have a higher mortality, more premorbid conditions and a higher incidence of multi organ failure.

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Elderly stay at the hospital for longer time.

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The incidence of infection or sepsis is not higher than young adult.

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Elderly show delayed hyper-metabolic response, increased hyperglycemic and hyperlipidemic responses.

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Elderly present inversed inflammatory response.

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Elderly show substantial delay in wound healing, predominantly due to alteration in characteristics of progenitor cells.

Despite advancements in treatment of severely burned patients, the death rate is still high in elderly. In this project, we investigate the reason behind this poor outcome. Our report highlights some of the deficiencies that we have observed in elderly patients and compare them to the young adults. Elderly have late immune responses which are necessary to fight the disease. Their body lacks some of the essential stem cells which are essential for skin healing. By learning the major deficiencies that come with this age group, we will be able to help elderly who have been subjected to burn injury.

Survivors versus nonsurvivors postburn: differences in inflammatory and hypermetabolic trajectories

OBJECTIVE

To evaluate whether a panel of common biomedical markers can be utilized as trajectories to determine survival in pediatric burn patients.

BACKGROUND

Despite major advances in clinical care, of the more than 1 million people burned in the United States each year, more than 4500 die as a result of their burn injuries. The ability to predict patient outcome or anticipate clinical trajectories using plasma protein expression would allow personalization of clinical care to optimize the potential for patient survival.

METHODS

A total of 230 severely burned children with burns exceeding 30% of the total body surface, requiring at least 1 surgical procedure were enrolled in this prospective cohort study. Demographics, clinical outcomes, and inflammatory and acute-phase responses (serum cytokines, hormones, and proteins) were determined at admission and at 11 time points for up to 180 days postburn. Statistical analysis was performed using a 1-way analysis of variance, the Student t test, χ test, and Mann-Whitney test where appropriate.

RESULTS

Survivors and nonsurvivors exhibited profound differences in critical markers of inflammation and metabolism at each time point. Nonsurvivors had significantly higher serum levels of interleukin (IL)-6, IL-8, granulocyte colony-stimulating factor, monocyte chemoattractant protein-1, C-reactive protein, glucose, insulin, blood urea nitrogen, creatinine, and bilirubin (P < 0.05). Furthermore, nonsurvivors exhibited a vastly increased hypermetabolic response that was associated with increases in organ dysfunction and sepsis when compared with survivors (P < 0.05).

CONCLUSIONS

Nonsurvivors have different trajectories in inflammatory, metabolic, and acute phase responses allowing differentiation of nonsurvivors from survivors and now possibly allowing novel predictive models to improve and personalize burn outcomes.

Insulin treatment modulates the host immune system to enhance Pseudomonas aeruginosa wound biofilms

Diabetes affects 25.8 million people in the United States, or 8.3% of the population, and these numbers are even higher in developing countries. Diabetic patients are more susceptible to the development of chronic wounds with debilitating bacterial infections than nondiabetics. Previously, we compared the ability of the opportunistic pathogen Pseudomonas aeruginosa to cause biofilm-associated infections in chronic wounds of diabetic and nondiabetic mice (C. Watters, K. DeLeon, U. Trivedi, J. A. Griswold, M. Lyte, K. J. Hampel, M. J. Wargo, and K. P. Rumbaugh, Med. Microbiol. Immunol. 202:131-141, 2013). Unexpectedly, we observed that insulin-treated diabetic mice had significantly more biofilm in their wounds, which correlated with higher antibiotic tolerance. Here, we investigated whether insulin treatment modulates the diabetic immune system to favor P. aeruginosa biofilm formation. Utilizing a murine chronic wound model, we found that DNA protected P. aeruginosa in the wounds of insulin-treated diabetic mice from antibiotic treatment. We also observed increased numbers of neutrophils, reduced numbers of macrophages, and increased cell death in the wounds of diabetic mice on insulin therapy. Taken together, these data suggest that high levels of lysed neutrophils in the wounds of diabetic mice on insulin, combined with fewer macrophages to remove the cellular debris, contribute to increased DNA levels, which enhance P. aeruginosa biofilms.

Clinical review: Glucose control in severely burned patients - current best practice

Tight glucose control changed the way many burn centers practice burn ICU care. However, after the initial impressive data, various clinical trials followed that showed mixed results. The objective of the present review is to discuss recent studies in the area of burn and critical care, and to identify the current best practice for current burn care providers. We reviewed relevant publications from PubMed and selected high-impact publications on tight glycemic control in various patient populations with a focus on burn patients. We conclude that in burns there seems to be a signal that insulin administration to a target range of 130 to 150 mg/dl is beneficial in terms of morbidity and mortality without the risk of hypoglycemia.

Tight glycemic control versus standard care after pediatric cardiac surgery

BACKGROUND

In some studies, tight glycemic control with insulin improved outcomes in adults undergoing cardiac surgery, but these benefits are unproven in critically ill children at risk for hyperinsulinemic hypoglycemia. We tested the hypothesis that tight glycemic control reduces morbidity after pediatric cardiac surgery.

METHODS

In this two-center, prospective, randomized trial, we enrolled 980 children, 0 to 36 months of age, undergoing surgery with cardiopulmonary bypass. Patients were randomly assigned to either tight glycemic control (with the use of an insulin-dosing algorithm targeting a blood glucose level of 80 to 110 mg per deciliter [4.4 to 6.1 mmol per liter]) or standard care in the cardiac intensive care unit (ICU). Continuous glucose monitoring was used to guide the frequency of blood glucose measurement and to detect impending hypoglycemia. The primary outcome was the rate of health care-associated infections in the cardiac ICU. Secondary outcomes included mortality, length of stay, organ failure, and hypoglycemia.

RESULTS

A total of 444 of the 490 children assigned to tight glycemic control (91%) received insulin versus 9 of 490 children assigned to standard care (2%). Although normoglycemia was achieved earlier with tight glycemic control than with standard care (6 hours vs. 16 hours, P<0.001) and was maintained for a greater proportion of the critical illness period (50% vs. 33%, P<0.001), tight glycemic control was not associated with a significantly decreased rate of health care-associated infections (8.6 vs. 9.9 per 1000 patient-days, P=0.67). Secondary outcomes did not differ significantly between groups, and tight glycemic control did not benefit high-risk subgroups. Only 3% of the patients assigned to tight glycemic control had severe hypoglycemia (blood glucose <40 mg per deciliter [2.2 mmol per liter]).

CONCLUSIONS

Tight glycemic control can be achieved with a low hypoglycemia rate after cardiac surgery in children, but it does not significantly change the infection rate, mortality, length of stay, or measures of organ failure, as compared with standard care. (Funded by the National Heart, Lung, and Blood Institute and others; SPECS ClinicalTrials.gov number, NCT00443599.).

Pseudomonas aeruginosa biofilms perturb wound resolution and antibiotic tolerance in diabetic mice

Diabetic patients are more susceptible to the development of chronic wounds than non-diabetics. The impaired healing properties of these wounds, which often develop debilitating bacterial infections, significantly increase the rate of lower extremity amputation in diabetic patients. We hypothesize that bacterial biofilms, or sessile communities of bacteria that reside in a complex matrix of exopolymeric material, contribute to the severity of diabetic wounds. To test this hypothesis, we developed an in vivo chronic wound, diabetic mouse model to determine the ability of the opportunistic pathogen, Pseudomonas aeruginosa, to cause biofilm-associated infections. Utilizing this model, we observed that diabetic mice with P. aeruginosa-infected chronic wounds displayed impaired bacterial clearing and wound closure in comparison with their non-diabetic littermates. While treating diabetic mice with insulin improved their overall health, it did not restore their ability to resolve P. aeruginosa wound infections or speed healing. In fact, the prevalence of biofilms and the tolerance of P. aeruginosa to gentamicin treatment increased when diabetic mice were treated with insulin. Insulin treatment was observed to directly affect the ability of P. aeruginosa to form biofilms in vitro. These data demonstrate that the chronically wounded diabetic mouse appears to be a useful model to study wound healing and biofilm infection dynamics, and suggest that the diabetic wound environment may promote the formation of biofilms. Further, this model provides for the elucidation of mechanistic factors, such as the ability of insulin to influence antimicrobial effectiveness, which may be relevant to the formation of biofilms in diabetic wounds.

What, how, and how much should patients with burns be fed?

The hypermetabolic response to severe burn injury is characterized by hyperdynamic circulation and profound metabolic, physiologic, catabolic, and immune system derangements. Failure to satisfy overwhelming energy and protein requirements after, and during, severe burn injury results in multiorgan dysfunction, increased susceptibility to infection, and death. Attenuation of the hypermetabolic response by various pharmacologic modalities is emerging as an essential component of the management of patients with severe burn injury. This review focuses on the more recent advances in therapeutic strategies to attenuate the hypermetabolic response and its postburn-associated insulin resistance.

Animal models of external traumatic wound infections

BACKGROUND

Despite advances in traumatic wound care and management, infections remain a leading cause of mortality,morbidity and economic disruption in millions of wound patients around the world. Animal models have become standard tools for studying a wide array of external traumatic wound infections and testing new antimicrobial strategies.

RESULTS

Animal models of external traumatic wound infections reported by different investigators vary in animal species used, microorganism strains, the number of microorganisms applied, the size of the wounds and for burn infections, the length of time the heated object or liquid is in contact with the skin.

METHODS

This review covers experimental infections in animal models of surgical wounds, skin abrasions, burns, lacerations,excisional wounds and open fractures.

CONCLUSIONS

As antibiotic resistance continues to increase,more new antimicrobial approaches are urgently needed.These should be tested using standard protocols for infections in external traumatic wounds in animal models.

Insulin protects against hepatic damage postburn

Burn injury causes hepatic dysfunction associated with endoplasmic reticulum (ER) stress and induction of the unfolded protein response (UPR). ER stress/UPR leads to hepatic apoptosis and activation of the Jun-N-terminal kinase (JNK) signaling pathway, leading to vast metabolic alterations. Insulin has been shown to attenuate hepatic damage and to improve liver function. We therefore hypothesized that insulin administration exerts its effects by attenuating postburn hepatic ER stress and subsequent apoptosis. Male Sprague Dawley rats received a 60% total body surface area (TBSA) burn injury. Animals were randomized to receive saline (controls) or insulin (2.5 IU/kg q. 24 h) and euthanized at 24 and 48 h postburn. Burn injury induced dramatic changes in liver structure and function, including induction of the ER stress response, mitochondrial dysfunction, hepatocyte apoptosis, and up-regulation of inflammatory mediators. Insulin decreased hepatocyte caspase-3 activation and apoptosis significantly at 24 and 48 h postburn. Furthermore, insulin administration decreased ER stress significantly and reversed structural and functional changes in hepatocyte mitochondria. Finally, insulin attenuated the expression of inflammatory mediators IL-6, MCP-1, and CINC-1. Insulin alleviates burn-induced ER stress, hepatocyte apoptosis, mitochondrial abnormalities, and inflammation leading to improved hepatic structure and function significantly. These results support the use of insulin therapy after traumatic injury to improve patient outcomes.

Nonantibiotic therapy for multidrug-resistant Pseudomonas aeruginosa in a patient with chronic burn wounds

The authors report a special case of nonantibiotic therapy in a adolescent boy with chronically infected wounds induced by inappropriate use of antibiotics. The result of microbial cultures of the secretions on the wounds indicated that the infection of multidrug-resistant Pseudomonas aeruginosa was resistant to aminoglycoside and cephalosporin but sensitive to carbapenem and quinolones. We formulated a management strategy including daily hydrotherapy, thermal radiation therapy, balanced fluid and electrolytes and intermittent transfusion of blood products, but antibiotics were not used. Twenty-four days after his hospitalization, an autologous split-meshed skin grafting was successfully performed. He was followed up for 6 months after discharge; both lower extremities had an excellent functional recovery. The therapy introduced in this report may be beneficial for chronic infected wounds.

Intensive insulin therapy in severely burned pediatric patients: a prospective randomized trial

RATIONALE

Hyperglycemia and insulin resistance have been shown to increase morbidity and mortality in severely burned patients, and glycemic control appears essential to improve clinical outcomes. However, to date no prospective randomized study exists that determines whether intensive insulin therapy is associated with improved post-burn morbidity and mortality.

OBJECTIVES

To determine whether intensive insulin therapy is associated with improved post-burn morbidity.

METHODS

A total of 239 severely burned pediatric patients with burns over greater than 30% of their total body surface area were randomized (block randomization 1:3) to intensive insulin treatment (n = 60) or control (n = 179).

MEASUREMENTS AND MAIN RESULTS

Demographics, clinical outcomes, sepsis, glucose metabolism, organ function, and inflammatory, acute-phase, and hypermetabolic responses were determined. Demographics were similar in both groups. Intensive insulin treatment significantly decreased the incidence of infections and sepsis compared with controls (P < 0.05). Furthermore, intensive insulin therapy improved organ function as indicated by improved serum markers, DENVER2 scores, and ultrasound (P < 0.05). Intensive insulin therapy alleviated post-burn insulin resistance and the vast catabolic response of the body (P < 0.05). Intensive insulin treatment dampened inflammatory and acute-phase responses by deceasing IL-6 and acute-phase proteins compared with controls (P < 0.05). Mortality was 4% in the intensive insulin therapy group and 11% in the control group (P = 0.14).

CONCLUSIONS

In this prospective randomized clinical trial, we showed that intensive insulin therapy improves post-burn morbidity. Clinical trial registered with www.clinicaltrials.gov (NCT00673309).