Showing papers by "Shriners Hospitals for Children - Galveston published in 2008"

Insulin resistance postburn: underlying mechanisms and current therapeutic strategies.

Abstract: The profound hypermetabolic response to burn injury is associated with insulin resistance and hyperglycemia, significantly contributing to the incidence of morbidity and mortality in this patient population. These responses are present in all trauma, surgical, or critically ill patients, but the severity, length, and magnitude is unique for burn patients. Although advances in therapeutic strategies to attenuate the postburn hypermetabolic response have significantly improved the clinical outcome of these patients during the past years, therapeutic approaches to overcome stress-induced hyperglycemia have remained challenging. Intensive insulin therapy has been shown to significantly reduce morbidity and mortality in critically ill patients. High incidence of hypoglycemic events and difficult blood glucose titrations have led to investigation of alternative strategies, including the use of metformin, a biguanide, or fenofibrate, a peroxisome proliferator-activated receptor (PPAR)-gamma agonist. Nevertheless, weaknesses and potential side affects of these drugs reinforces the need for better understanding of the molecular mechanisms underlying insulin resistance postburn that may lead to novel therapeutic strategies further improving the prognosis of these patients. This review aims to discuss the mechanisms underlying insulin resistance induced hyperglycemia postburn and outlines current therapeutic strategies that are being used to modulate hyperglycemia after thermal trauma.

NK but not CD1-restricted NKT cells facilitate systemic inflammation during polymicrobial intra-abdominal sepsis.

Abstract: Evidence suggests that NK and NKT cells contribute to inflammation and mortality during septic shock caused by cecal ligation and puncture (CLP). However, the specific contributions of these cell types to the pathogenesis of CLP-induced septic shock have not been fully defined. The goal of the present study was to determine the mechanisms by which NK and NKT cells mediate the host response to CLP. Control, NK cell-deficient, and NKT cell-deficient mice underwent CLP. Survival, cytokine production, and bacterial clearance were measured. NK cell trafficking and interaction with myeloid cells was also studied. Results show that mice treated with anti-asialoGM1 (NK cell deficient) or anti-NK1.1 (NK/NKT cell deficient) show less systemic inflammation and have improved survival compared with IgG-treated controls. CD1 knockout mice (NKT cell deficient) did not demonstrate decreased cytokine production or improved survival compared with wild type mice. Trafficking studies show migration of NK cells from blood and spleen into the inflamed peritoneal cavity where they appear to facilitate the activation of peritoneal macrophages (F4-80 + GR-1 − ) and F4-80 + Gr-1 + myeloid cells. These findings indicate that NK but not CD1-restricted NKT cells contribute to acute CLP-induced inflammation. NK cells appear to mediate their proinflammatory functions during septic shock, in part, by migration into the peritoneal cavity and amplification of the proinflammatory activities of specific myeloid cell populations. These findings provide new insights into the mechanisms used by NK cells to facilitate acute inflammation during septic shock.

Are serum cytokines early predictors for the outcome of burn patients with inhalation injuries who do not survive

Abstract: Introduction Severely burned patients suffering from inhalation injury have a significantly increased risk for mortality compared with burned patients without inhalation injury. Severe burn is associated with a distinct serum cytokine profile and alterations in cytokines that contribute to morbidity and mortality. The aim of the present study was therefore to determine whether severely burned pediatric patients with concomitant inhalation injury who had a fatal outcome exhibited a different serum cytokine profile compared with burn patients with inhalation injury who survived. Early identification followed by appropriate management of these high-risk patients may lead to improved clinical outcome. Methods Thirteen severely burned children with inhalation injury who did not survive and 15 severely burned pediatric patients with inhalation injury who survived were enrolled in the study. Blood was collected within 24 hours of admission and 5 to 7 days later. Cytokine levels were profiled using multiplex antibody coated beads. Inhalation injury was diagnosed by bronchoscopy during the initial surgery. The number of days on the ventilator, peak inspiratory pressure rates, arterial oxygen tension (PaO2)/ fraction of inspired oxygen (FiO2) ratio and incidence of acute respiratory distress syndrome were recorded for those patients. Results Significantly altered levels of IL-4, IL-6, IL-7, IL-10, and IL-13 were detected within the first 7 days after admission in serum from burn pediatric patients with concomitant inhalation injury who did not survive when compared with similar patients who did (P < 0.05). Alterations in these cytokines were associated with increased incidence of acute respiratory distress syndrome, number of days under ventilation, increased peak inspiratory pressure, and lower PaO2/FiO2 ratio in this patient population. Multiple logistic regression analysis revealed that patients with increased IL-6 and IL-10 as well as decreased IL-7 serum levels had a significantly greater risk for mortality (P < 0.05).

Urinary Cortisol and Catecholamine Excretion after Burn Injury in Children

Abstract: Introduction: A severe burn causes increased levels of urine cortisol and catecholamines. However, little is known about the magnitude of this increase or how and when the levels return to normal. The purpose of this study was to determine in a large clinical prospective trial the acute and long-term pattern of urine cortisol and catecholamine expression in severely burned children. Methods: Pediatric patients with burns greater than 40% total body surface area (TBSA), admitted to our unit over a 6-yr period, were included into the study. Clinical data including length of stay, number of operations, and duration and number of infections were determined. Patients had regular 24-h urine collections during their acute admission and reconstructive periods. Urine collections were analyzed for cortisol, epinephrine, and norepinephrine. Each urine cortisol was compared with age-adjusted reference ranges. Ninety-five percent confidence intervals and ANOVA analysis were used where appropriate. Results: Two hundred...

Prophylactic Treatment with Fms-Like Tyrosine Kinase-3 Ligand after Burn Injury Enhances Global Immune Responses to Infection

Abstract: Severely burned patients are susceptible to infections with opportunistic organisms due to altered immune responses and frequent wound contamination. Immunomodulation to enhance systemic and local responses to wound infections may be protective after burn injury. We previously demonstrated that pretreatments with fms-like tyrosine kinase-3 (Flt3) ligand (Flt3L), a dendritic cell growth factor, increase the resistance of mice to a subsequent burn injury and wound infection by a dendritic cell-dependent mechanism. This study was designed to test the hypothesis that Flt3L administration after burn injury decreases susceptibility to wound infections by enhancing global immune cell activation. Mice were treated with Flt3L after burn injury and examined for survival, wound and systemic bacterial clearance, and immune cell activation after wound inoculation with Pseudomonas aeruginosa. To gain insight into the local effects of Flt3L at the burn wound, localization of Langerhans cells was examined. Mice treated with Flt3L had significantly greater numbers of CD25-expressing T cells and CD69-expressing T and B cells, neutrophils, and macrophages after, but not before, infection. Overall leukocyte apoptosis in response to infection was decreased with Flt3L treatment. Survival and local and systemic bacterial clearance were enhanced by Flt3L. Langerhans cells appeared in the dermis of skin bordering the burn wound, and further increased in response to wound infection. Flt3L augmented the appearance of Langerhans cells in response to both injury and infection. These data suggest that dendritic cell enhancement by Flt3L treatments after burn injury protects against opportunistic infections through promotion of local and systemic immune responses to infection.

Effects of a 12-week rehabilitation program with music & exercise groups on range of motion in young children with severe burns.

Abstract: Previous studies indicate that rehabilitation programs supplemented with a strength and endurance-based exercise program improve lean body mass, pulmonary function, endurance, strength, and functional outcomes in severely burned children over the age of 7-years when compared with standard of care (SOC). To date, supplemental exercise programming for severely burned children under the age of 7-years has not yet been explored. The purpose of this study was to determine if a 12-week rehabilitation program supplemented with music & exercise, was more effective in improving functional outcomes than the SOC alone. This is a descriptive study that measured elbow and knee range of motion (ROM) in 24 severely burned children between ages 2 and 6 years. Groups were compared for demographics as well as active and passive ROM to bilateral elbows and knees. A total of 15 patients completed the rehabilitation with supplemental music and exercise, and data was compared with 9 patients who received SOC. Patients receiving the 12-week program significantly improved ROM in all joints assessed except for one. Patients receiving SOC showed a significant improvement in only one of the joints assessed. Providing a structured supplemental music and exercise program in conjunction with occupational and physical therapy seems to improve both passive and active ROM to a greater extent than the SOC alone.

Combined anticoagulants ameliorate acute lung injury in sheep after burn and smoke inhalation.

Abstract: Burn and smoke inhalation-related multiple organ dysfunction is associated with a severe fall in the plasma concentration of antithrombin. Therefore the aim of the present study was to test the hypothesis that intravenous administration of recombinant human antithrombin in combination with aerosolized heparin will ameliorate acute lung injury in sheep exposed to cutaneous burn and smoke inhalation. Sheep were prepared operatively for study and, 7 days post-surgery, sheep were given a cutaneous burn (40% of total body surface area, third-degree burn) and insufflated with cotton smoke (48 breaths, <40 degrees C) under halothane anaesthesia. After injury, sheep were placed on a ventilator and resuscitated with Ringer's lactate solution. The animals were divided into three groups: sham group (non-injured and non-treated; n=6), saline group (injured and received saline; n=6) and rhAT.iv.+Hep group [injured and treated with rhAT (recombinant human antithrombin) and heparin; n=6]. In the rhAT.iv.+Hep group, rhAT was infused continuously for 48 h starting 1 h post-injury with a dose of 0.34 mg.h(-1).kg(-1) of body weight and heparin (10000 units) was aerosolized every 4 h starting at 1 h post-injury. The experiment lasted 48 h. Haemodynamics were stable in sham group, whereas the saline-treated sheep developed multiple signs of acute lung injury, including decreased pulmonary gas exchange, increased inspiratory pressures, extensive airway obstruction and increased pulmonary oedema. These pathological changes were associated with a severe fall in plasma antithrombin concentration, lung tissue accumulation of leucocytes and excessive production of NO. Treatment of injured sheep with anticoagulants attenuated all of the pulmonary pathophysiology observed. In conclusion, the results provide definitive evidence that anticoagulant therapy may be a novel and effective treatment tool in the management of burn patients with concomitant smoke inhalation injury.

Human Mitochondrial Oxidative Capacity Is Acutely Impaired After Burn Trauma

Abstract: Background Mitochondrial proteins and genes are damaged after burn injury in animals and are assessed in human burn patients in this study. Methods The rates of maximal muscle mitochondrial oxidative capacity (adenosine triphosphate production) and uncoupled oxidation (heat production) for both palmitate and pyruvate were measured in muscle biopsies from 40 children sustaining burns on more than 40% of their body surface area and from 13 healthy children controls. Results Maximal mitochondrial oxidation of pyruvate and palmitate were reduced in burn patients compared with controls (4.0 ± .2:1.9 ± .1 μmol O 2 /citrate synthase activity/mg protein/min pyruvate; control:burn; P 2 /citrate synthase activity/mg protein/min palmityl CoA; control:burn; P = .003). Uncoupled oxidation was the same between groups. Conclusions The maximal coupled mitochondrial oxidative capacity is severely impaired after burn injury, although there are no alterations in the rate of uncoupled oxidative capacity. It may be that the ratio of these indicates that a larger portion of energy production in trauma patients is wasted through uncoupling, rather than used for healing.

Insulin decreases inflammatory signal transcription factor expression in primary human liver cells after LPS challenge.

Abstract: Hepatic homeostasis is essential for survival in critically ill and burned patients. Insulin administration improves survival and decreases infections in these patients. To determine the molecular mechanisms, the aim of the present study was to establish a stress model using primary human hepatocytes (PHHs) and to study the effects of insulin on the hepatic inflammatory signaling cascade. Liver tissue was obtained from general surgical patients, and PHHs were isolated and maintained in culture. Primary hepatocyte cultures were challenged with various doses of lipopolysaccharide (LPS), and the inflammatory signal transcription cascade was determined by real-time PCR. In subsequent experiments, primary hepatocyte cultures were challenged with LPS and insulin was added in various doses. Glucose was determined by colorimetric assays. PHHs treated with 100 µg/mL LPS showed a profound inflammatory reaction with increased expression of interleukin (IL)-6, IL-10, IL-1β, tumor necrosis factor (TNF), and signal transducer and activator of transcription 5 (STAT-5). Insulin at 10 IU/mL significantly decreased IL-6, TNF, and IL-1β at pretranslational levels, an effect associated with decreased STAT-5 mRNA expression (P < 0.05). Glucose concentration and cellular metabolic activity were not different between controls and insulin-treated cells. Based on our results, we suggest that primary hepatocyte cultures can be used to study the effect of LPS on the inflammatory cascade. Insulin decreases hepatic cytokine expression, which is associated with decreased STAT-5 expression.

Lipid Metabolism in Diet-Induced Obese Rabbits Is Similar to That of Obese Humans

Abstract: Whereas diet-induced obese rabbits have been used to study various aspects of obesity, alterations of lipid metabolism in this model have not been clarified. This study aimed to compare plasma nonesterified fatty acid (NEFA) and triglyceride (TG) kinetics in obese and lean rabbits by means of U-(13)C16-palmitate infusion. Young female rabbits consumed either a high-fat diet (49% energy from fat) ad libitum to develop obesity (n = 6) or a normal diet (7.9% energy from fat) as lean control (n = 5). After 10 wk of feeding, the body weight of obese rabbits (5.33 +/- 0.05 kg) was greater (P < 0.001) than that of lean rabbits (3.89 +/- 0.07 kg). The obese rabbits had higher concentrations of plasma NEFA and TG and a greater rate of fatty acid (FA) turnover. Whereas the fractional secretion rates of hepatic TG did not differ, 100% of hepatic secretory TG was synthesized from plasma NEFA in the lean rabbits compared to 59% in the obese rabbits (P < 0.001). In the lean rabbits, hepatic lipase-mediated hydrolysis of lipoprotein TG did not contribute to the FA pool for synthesis of secretory TG, consistent with the naturally occurring deficit in hepatic lipase in this species. We conclude that lipid metabolism in diet-induced obese rabbits is similar to that in obese humans. The deficiency in hepatic lipase in rabbits simplifies the quantitation of hepatic lipid kinetics.

Role of Polymorphonuclear Neutrophils on Infectious Complications Stemming from Enterococcus faecalis Oral Infection in Thermally Injured Mice

Abstract: Thermally injured mice are susceptible to Enterococcus faecalis translocation. In this study, the role of polymorphonuclear neutrophils (PMN) on the development of sepsis stemming from E. faecalis translocation was studied in SCID-beige (SCIDbg) mice depleted of PMN (SCIDbgN mice) or macrophages (Mphi) and PMN (SCIDbgMN mice). Sepsis was not developed in SCIDbgN mice orally infected with E. faecalis, while the orally infected pathogen spread systemically in the same mice inoculated with PMN from thermally injured mice (TI-PMN). SCIDbgMN mice were shown to be greatly susceptible to sepsis caused by E. faecalis translocation, while orally infected E. faecalis did not spread into sepsis in the same mice that were previously inoculated with Mphi from unburned SCIDbg mice (resident Mphi). In contrast, orally infected E. faecalis spread systemically in SCIDbgMN mice inoculated with resident Mphi and TI-PMN, while all SCIDbgMN mice inoculated in combination with resident Mphi and PMN from unburned SCIDbg mice survived after the infection. After cultivation with TI-PMN in a dual-chamber transwell, resident Mphi converted to alternatively activated Mphi, which are inhibitory on the generation of classically activated Mphi (typical effector cells in host antibacterial innate immunities). TI-PMN were characterized as immunosuppressive PMN (PMN-II) with abilities to produce cc-chemokine ligand-2 and IL-10. These results indicate that PMN-II appearing in response to burn injury impair host antibacterial resistance against sepsis stemming from E. faecalis translocation through the conversion of resident Mphi to alternatively activated Mphi.

Gr-1(+)CD11b(+) cells as an accelerator of sepsis stemming from Pseudomonas aeruginosa wound infection in thermally injured mice.

Abstract: Using a mouse model of thermal injury, we studied why antimicrobial peptides are not produced at the burn-site tissues and how this defect contributes to the increased susceptibility to Pseudomonas aeruginosa burn-wound infection. Logarithmic growth of P. aeruginosa was demonstrated locally (at the burn site) and systemically (in circulation) in thermally injured mice exposed to 10(2) CFU/mouse of the pathogen beneath the burn wound. However, neither systemic nor local growth of the pathogen was observed in sham burn mice when they were infected intradermally with 10(6) CFU/mouse P. aeruginosa. Murine beta-defensins (MBDs) were detected in the skin homogenates of sham burn mice. However, the amounts of MBDs were reduced greatly in the same tissue homogenates from thermally injured mice. Gr-1(+)CD11b(+) cells, with an ability to suppress antimicrobial peptide production by skin keratinocytes, were isolated from tissues surrounding the burn areas, and these cells were not obtained from skin tissues of sham burn mice. After intradermal inoculation of Gr-1(+)CD11b(+) cells, which were isolated from burn-site tissues, the production of antimicrobial peptides around the cell-inoculation site of sham burn mice decreased. Also, like thermally injured mice, these mice were shown to be susceptible to P. aeruginosa intradermal infection. These results indicate that sepsis stemming from P. aeruginosa burn-wound infection is accelerated by burn-induced Gr-1(+)CD11b(+) cells with abilities to suppress antimicrobial peptide production by epidermal keratinocytes.

CD4+ T-cell depletion is not associated with alterations in survival, bacterial clearance, and inflammation after cecal ligation and puncture.

Abstract: Our recent studies indicate that mice depleted of T cells that bear the alphabeta T-cell receptor (alphabeta T cells) show less inflammation, less physiological dysfunction, and improved survival after cecal ligation and puncture (CLP) compared with control mice. Classic CD4(+) and CD8(+) T cells comprise most of the alphabeta T-cell population. We previously showed that CD8(+) T cells, in conjunction with natural killer (NK) cells, participate in CLP-induced inflammation. However, the contribution of CD4(+) T cells to the early inflammatory response caused by CLP is largely undefined. In the present study, we evaluated CLP-induced mortality, bacterial clearance, and inflammation in mice that were depleted of CD4(+) T cells. Compared with control mice, CD4 knockout mice and wild-type mice treated with anti-CD4 did not show significant differences in survival, cytokine production, and systemic bacterial counts. The combined depletion of CD4(+) T and NK cells resulted in improved survival and decreased cytokine production compared with mice possessing a full lymphocyte complement, especially when CD4(+) T and NK cell-deficient mice were treated with imipenem. These improvements were nearly identical to those observed in mice depleted only of NK cells. These studies show that CD4(+) T cells do not seem to play a critical role in facilitating the early inflammatory response caused by CLP.

Mixed-methods exploration of parents' health information understanding.

Abstract: Health literacy—the ability to read, understand, and use health information to make health care decisions—affects health care outcomes, hospitalization costs, and readmission. The purpose of this exploratory mixed-methods study is to determine how two different parent groups (English speaking and Spanish speaking) understand medical care for their children and the procedural and research consent forms required by that care. Quantitative and qualitative data are gathered and compared concurrently. Differences between groups are found in age, grade completed, Short Test of Functional Health Literacy in Adults scores, and ways of understanding health information. Identifying how parents understand health information is the first step in providing effective family-centered health care education.

Insulin sensitivity is related to fat oxidation and protein kinase C activity in children with acute burn injury.

Abstract: Impaired fatty acid oxidation occurs with type 2 diabetes and is associated with accumulations of intracellular lipids, which may increase diacylglycerol (DAG), stimulate protein kinase C activity, and inactivate insulin signaling. Glucose and fat metabolism are altered in burn patients, but have never been related to intracellular lipids or insulin signaling. Thirty children sustaining >40% total body surface area burns were studied acutely with glucose and palmitate tracer infusions and a hyper-insulinemic euglycemic clamp. Muscle triglyceride, DAG, fatty acyl CoA, and insulin signaling were measured. Liver and muscle triglyceride levels were measured with magnetic resonance spectroscopy. Muscle samples from healthy children were controls for DAG concentrations. Insulin sensitivity was reduced and correlated with whole body palmitate beta-oxidation (P = .004). Muscle insulin signaling was not stimulated by hyper-insulinemia. Tissue triglyceride concentrations and activated protein kinase C-beta were elevated, whereas the concentration of DAG was similar to the controls. Free fatty acid profiles of muscle triglyceride did not match DAG. Insulin resistance following burn injury is accompanied by decreased insulin signaling and increased protein kinase C-beta activation. The best metabolic predictor of insulin resistance in burned patients was palmitate oxidation.

Assessment of Lung Inflammation in a Mouse Model of Smoke Inhalation and Burn Injury: Strain-Specific Differences

Abstract: To test concepts developed in our ovine model of acute respiratory distress syndrome, specifically the roles of neuropeptides and other peptide mediators, a recently developed murine model of combined smoke inhalation and burn (SB) injury was extended by applying methods for quantitative assessment of acute inflammation in the lung. Mice received SB injury per protocol, n = 5 to 7 per group. Mice were anesthetized with i.p. ketamine/xylazine, endotracheally intubated, and exposed to cooled cotton smoke (4 × 30 sec for Balb/C, 2 × 30 sec for C57BL/6). After s.c. injection of 1 mL 0.9% saline, each received a 40% total body surface area (TBSA) flame burn. Buprenorphine (0.1 mg/kg) was given i.p. for postoperative analgesia; 0.9% saline was given i.p. at 4 mL/kg per %TBSA burn. Evans Blue dye (EB) was injected i.v. 15 min before sacrifice. Lung wet/dry weight ratio was measured. In other animals, after vascular perfusion with buffered saline, lungs were sampled and analyzed for myeloperoxidase (MPO),...

Brussels 2007 Roundtable on Metabolism in Sepsis and Multiple Organ Failure

Abstract: At the 2007 International Symposium on Intensive Care and Emergency Medicine (ISICEM) in Brussels, a roundtable conference on "Metabolic Support in Sepsis and Multiple Organ Failure" was held The roundtable was endorsed by the European Society of Intensive Care Medicine, the Society of Critical Care Medicine, the European Society for Clinical Nutrition and Metabolism, and the American Society for Parenteral and Enteral Nutrition Metabolic support in intensive care has become an exciting topic in recent years, with improved understanding of the effects of compromised mitochondrial function, studies demonstrating outcome benefits of tight glucose control, new insights into the mechanisms behind insulin resistance, recognition of glutamine and antioxidants as key nutrients, and emerging knowledge concerning the interactions between metabolism and endocrinology Together, these aspects have generated an increased interest in the importance of metabolism in intensive care medicine, reflected in the programs and abstracts at international congresses of the past few years This roundtable's participants each gave a presentation within their specific area of expertise, and each was followed by general discussion Discussions became heated as new concepts and ideas were debated New data will be discussed in this summary which reveals metabolic and nutrition interventions that could lead to major improvements in clinically relevant outcomes