Amino Acid Availability Regulates the Effect of Hyperinsulinemia on Skin Protein Metabolism in Pigs.

The effects of amino acid supply and insulin infusion on skin protein kinetics (fractional synthesis rate (FSR), fractional breakdown rate (FBR), and net balance (NB)) in pigs were investigated. Four-month-old pigs were divided into four groups as follows: control, insulin (INS), amino acid (AA), and INS + AA groups based on the nutritional and hormonal conditions. l-[ring-(13)C6]Phenylalanine was infused. FBR was estimated from the enrichment ratio of arterial phenylalanine to intracellular free phenylalanine. Plasma INS was increased (p < 0.05) in the INS and INS + AA groups. Plasma glucose was maintained by infusion of glucose in the groups receiving INS. The interventions did not change the NB of skin protein. However, the interventions affected the FSR and FBR differently. An infusion of INS significantly increased both FSR and FBR, although AA infusion did not. When an AA infusion was added to the infusion of insulin (INS + AA group), FSR and FBR were both lower when compared with the INS group. Our data demonstrate that in anesthetized pigs INS infusion did not exert an anabolic effect, but rather it increased AA cycling into and out of skin protein. Because co-infusion of AAs with INS ameliorated this effect, it is likely that the increased AA cycling during INS infusion was related to AA supply. Although protein kinetics were affected by both INS and AAs, none of the interventions affected the skin protein deposition. Thus, skin protein content is closely regulated under normal circumstances and is not subject to transient changes in AAs or hormonal concentrations.

A novel stable isotope tracer method to measure muscle protein fractional breakdown rate during a physiological non-steady-state condition.

The measurement of the fractional breakdown rate (FBR) of muscle proteins during physiological non-steady state of amino acids (AAs) presents some challenges. Therefore, the goal of the present experiment was to modify the bolus stable isotope tracer injection approach to determine both fractional synthesis rate (FSR) and FBR of leg muscle protein during a physiological non-steady state of AAs. The approach uses the traditional precursor-product principle but is modified with the assumption that inward transport of AAs is proportional to their plasma concentrations. The FBR value calculated from the threonine tracer served as a reference to evaluate the validity of the FBR measurement from the phenylalanine tracer, which was under a non-steady-state condition due to the concomitant injection of unlabeled phenylalanine. Plasma phenylalanine concentration increased more than fourfold after the bolus injection, and thereafter it decreased exponentially, whereas the threonine concentration remained stable. FBR values were similar with the two tracers [0.133 ± 0.003 and 0.148 ± 0.003%/h (means ± SE) for the phenylalanine and threonine tracers, respectively, P > 0.05]. In addition, FSR values for the two tracers were similar (0.069 ± 0.002 and 0.067 ± 0.001%/h for the phenylalanine and threonine tracers, respectively, P > 0.05), indicating that the traditional FSR approach can also be used in the non-steady state. Accordingly, net balance (NB) values were similar (-0.065 ± 0.002 and -0.081 ± 0.002%/h for the phenylalanine and threonine tracers, respectively, P > 0.05). This new method of measuring muscle protein FBR during physiological non-steady state gives reliable results and allows simultaneous measurement of muscle protein FSR and thus a calculation of NB.

Skeletal muscle is anabolically unresponsive to an amino acid infusion in pediatric burn patients 6 months postinjury.

OBJECTIVE: To evaluate leg muscle, whole-body muscle, and whole-body nonmuscle protein response to anabolic signaling of amino acids in pediatric burn patients at 6 months after injury. BACKGROUND: Burn injury is associated with a catabolic state persisting years after the injury. The tissue response to nutritional signaling (eg, amino acids) plays a critical role in tissue protein net balance via coordination of protein synthesis and breakdown mechanisms. METHODS: A total of 10 patients (7.4 ± 3.8 years; 27.4 ± 14.7 kg) and 5 healthy young males (22 ± 3 years; 76 ± 15 kg) underwent an 8-hour stable isotope infusion study. During the last 3 hours, an amino acid solution (10% Travasol, Clintec Nutrition, Deerfield, IL) was infused. Femoral arterial and venous blood samples and muscle biopsy samples were collected throughout the study. A P value of less than 0.05 was considered statistically different. RESULTS: During amino acid infusion, leg muscle protein synthesis rate significantly increased (P < 0.05) in both groups, however, in the burn group, protein breakdown also increased, although nonsignificantly. As a result, protein net balance remained negative. In the control group, breakdown nonsignificantly decreased resulting in a significant increase (P < 0.05) in muscle protein net balance. Whole-body protein breakdown was significantly higher in the burn patients. CONCLUSION: In pediatric burn patients at 6 months postinjury, leg muscle protein net deposition is unresponsive to amino acid infusion; and whole-body protein breakdown is significantly higher than in the control group.

Beneficial effects of insulin on cell proliferation and protein metabolism in skin donor site wound.

BACKGROUND: Insulin has been demonstrated to accelerate skin wound healing; however, its effects on wound metabolism have not been adequately studied. MATERIALS AND METHODS: Adult rabbits were prepared by creation of skin donor site wound on the back, catheterization of the carotid artery and jugular vein, and placement of a nasogastric feeding tube under general anesthesia. The rabbits were given total enteral nutrition thereafter. On day 5 stable isotope tracers were infused to measure the kinetics of protein (reflecting tissue repair) and DNA (reflecting cell proliferation) in the wound. During the isotope tracer infusion, regular human insulin was infused at 2.5 mU/kg per min with concomitant glucose infusion for euglycemia in an insulin group but not in a control group. RESULTS: Plasma insulin concentration was 140±26 µU/mL in the insulin group (n=8), greater (P<0.001) than that of 16±3 µU/mL in the control group (N=8). In the insulin group the fractional synthetic rates of wound protein and DNA were 9.0±1.2 and 5.4±0.5%/day, greater (P < or=0.05) than those of 6.4±0.5 and 4.0±0.6%/day in the control group, respectively. Wound protein fractional breakdown rates were not significantly (P =0.2) different; net protein deposition rate was ~50% greater in the insulin than in the control group, although the difference was not statistically different (P=0.2). CONCLUSIONS: Insulin infusion increased wound protein and DNA synthesis, which are anticipated to promote tissue repair and reepithelialization.

Intensive insulin therapy improves insulin sensitivity and mitochondrial function in severely burned children.

OBJECTIVE: To institute intensive insulin therapy protocol in an acute pediatric burn unit and study the mechanisms underlying its benefits. DESIGN: Prospective, randomized study. SETTING: An acute pediatric burn unit in a tertiary teaching hospital. PATIENTS: Children, 4-18 yrs old, with total body surface area burned > or =40% and who arrived within 1 wk after injury were enrolled in the study. INTERVENTIONS: Patients were randomized to one of two groups. Intensive insulin therapy maintained blood glucose levels between 80 and 110 mg/dL. Conventional insulin therapy maintained blood glucose < or =215 mg/dL. MEASUREMENTS AND MAIN RESULTS: Twenty patients were included in the data analysis consisting of resting energy expenditure, whole body and liver insulin sensitivity, and skeletal muscle mitochondrial function. Studies were performed at 7 days postburn (pretreatment) and at 21 days postburn (posttreatment). Resting energy expenditure significantly increased posttreatment (1476 +/- 124 to 1925 +/- 291 kcal/m(2) x day; p = .02) in conventional insulin therapy as compared with a decline in intensive insulin therapy. Glucose infusion rate was identical between groups before treatment (6.0 +/- 0.8 conventional insulin therapy vs. 6.8 +/- 0.9 mg/kg x min intensive insulin therapy; p = .5). Intensive insulin therapy displayed a significantly higher glucose clamp infusion rate posttreatment (9.1 +/- 1.3 intensive insulin therapy versus 4.8 +/- 0.6 mg/kg x min conventional insulin therapy, p = .005). Suppression of hepatic glucose release was significantly greater in the intensive insulin therapy after treatment compared with conventional insulin therapy (5.0 +/- 0.9 vs. 2.5 +/- 0.6 mg/kg x min; intensive insulin therapy vs. conventional insulin therapy; p = .03). States 3 and 4 mitochondrial oxidation of palmitate significantly improved in intensive insulin therapy (0.9 +/- 0.1 to 1.7 +/- 0.1 microm O(2)/CS/mg protein/min for state 3, p = .004; and 0.7 +/- 0.1 to 1.3 +/- 0.1 microm O(2)/CS/mg protein/min for state 4, p < .002), whereas conventional insulin therapy remained at the same level of activity (0.9 +/- 0.1 to 0.8 +/- 0.1 microm O(2)/CS/mg protein/min for state 3, p = .4; 0.6 +/- 0.03 to 0.7 +/- 0.1 microm O(2)/CS/mg protein/min, p = .6). CONCLUSION: Controlling blood glucose levels < or =120 mg/dL using an intensive insulin therapy protocol improves insulin sensitivity and mitochondrial oxidative capacity while decreasing resting energy expenditure in severely burned children.

Donor site wound protein synthesis correlates with length of acute hospitalization in severely burned children.

Autografting of burn wounds results in generation of donor site wounds. Here we measured donor site wound protein fractional synthesis rate (FSR) in a burn pediatric population and showed that FSR increases over time postsurgery and correlates with the length of hospital stay (LOS) normalized for total body surface area (TBSA) burn size. 3.9 +/- 1.1 days after the grafting surgery patients participated in a metabolic study consisting of continuous infusion of l-[ring-(2)H(5)]-phenylalanine and donor site wound punch biopsies. Donor site wound protein FSR was 10.4 +/- 7.5%/day. Wound FSR demonstrated linear correlation with the time postsurgery (p<0.05). Multiple regression analysis showed that LOS/TBSA correlated with donor site wound protein FSR and time postsurgery (p<0.001) and the following equation describes the relationship: estimated LOS/TBSA=(FSR-12.95-1.414 x postsurgery day)/(-17.8). This equation predicted that FSR corrected for the postsurgery day when the metabolic study was conducted accounted for 67% of the variability (r(2)=0.673) in the LOS/TBSA. Donor site wound protein FSR correlated to LOS/TBSA of burn patients admitted to the intensive care unit. Measurement of protein deposition in regenerating donor site wound using stable isotope technique provides a quantitative measure of wound healing.

Randomized controlled trial to determine the efficacy of long-term growth hormone treatment in severely burned children.

BACKGROUND: Recovery from a massive burn is characterized by catabolic and hypermetabolic responses that persist up to 2 years and impair rehabilitation and reintegration. The objective of this study was to determine the effects of long-term treatment with recombinant human growth hormone (rhGH) on growth, hypermetabolism, body composition, bone metabolism, cardiac work, and scarring in a large prospective randomized single-center controlled clinical trial in pediatric patients with massive burns. PATIENTS AND METHODS: A total of 205 pediatric patients with massive burns over 40% total body surface area were prospectively enrolled between 1998 and 2007 (clinicaltrials.gov ID NCT00675714). Patients were randomized to receive either placebo (n = 94) or long-term rhGH at 0.05, 0.1, or 0.2 mg/kg/d (n = 101). Changes in weight, body composition, bone metabolism, cardiac output, resting energy expenditure, hormones, and scar development were measured at patient discharge and at 6, 9, 12, 18, and 24 months postburn. Statistical analysis used Tukey t test or ANOVA followed by Bonferroni correction. Significance was accepted at P < 0.05. RESULTS: RhGH administration markedly improved growth and lean body mass, whereas hypermetabolism was significantly attenuated. Serum growth hormone, insulin-like growth factor-I, and IGFBP-3 was significantly increased, whereas percent body fat content significantly decreased when compared with placebo, P < 0.05. A subset analysis revealed most lean body mass gain in the 0.2 mg/kg group, P < 0.05. Bone mineral content showed an unexpected decrease in the 0.2 mg/kg group, along with a decrease in PTH and increase in osteocalcin levels, P < 0.05. Resting energy expenditure improved with rhGH administration, most markedly in the 0.1 mg/kg/d rhGH group, P < 0.05. Cardiac output was decreased at 12 and 18 months postburn in the rhGH group. Long-term administration of 0.1 and 0.2 mg/kg/d rhGH significantly improved scarring at 12 months postburn, P < 0.05. CONCLUSION: This large prospective clinical trial showed that long-term treatment with rhGH effectively enhances recovery of severely burned pediatric patients.

The leading causes of death after burn injury in a single pediatric burn center.

INTRODUCTION: Severe thermal injury is characterized by profound morbidity and mortality. Advances in burn and critical care, including early excision and grafting, aggressive resuscitation and advances in antimicrobial therapy have made substantial contributions to decrease morbidity and mortality. Despite these advances, death still occurs. Our aim was to determine the predominant causes of death in burned pediatric patients in order to develop new treatment avenues and future trajectories associated with increased survival. METHODS: Primary causes of death were reviewed from 144 pediatric autopsy reports. Percentages of patients that died from anoxic brain injuries, sepsis, or multi-organ failure were calculated by comparing to the total number of deaths. Data was stratified by time (from 1989 to 1999, and 1999 to 2009), and gender. Statistical analysis was done by chi-squared, Student's t-test and Kaplan-Meier for survival where applicable. Significance was accepted as P < 0.05. RESULTS: Five-thousand two-hundred-sixty patients were admitted after burn injury from July 1989 to June 2009, and of those, 145 patients died after burn injury. Of these patients, 144 patients had an autopsy. The leading causes of death over 20 years were sepsis (47%), respiratory failure (29%), anoxic brain injury (16%), and shock (8%). From 1989 to 1999, sepsis accounted for 35% of deaths but increased to 54% from 1999 to 2009, with a significant increase in the proportion due to antibiotic resistant organisms (P < 0.05). CONCLUSIONS: Sepsis is the leading cause of death after burn injury. Multiple antibiotic resistant bacteria now account for the bulk of deaths due to sepsis. Further improvement in survival may require improved strategies to deal with this problem.

Urinary cortisol and catecholamine excretion after burn injury in children.

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 twelve patients were included in the study (75 females and 137 males), with a mean +/- sem TBSA of 58 +/- 1% (third-degree 45 +/- 2%) and mean age of 9 +/- 0.4 yr. Urinary cortisol levels were significantly increased (3- to 5-fold) up to 100 d after the burn and then approached normal levels (P < 0.05). The rise in urine cortisol was significantly higher in male than female patients (P < 0.05). Early hypercortisolemia was associated with increased duration of severe infection (P < 0.05). Persistent hypercortisolemia was associated with increases in both infection rates and duration of severe infection (P < 0.05). Urinary catecholamines showed a significant increase at 11-20 d after the burn (P < 0.05). Urinary norepinephrine levels were significantly increased up to 20 d and then returned to normal (P < 0.05). CONCLUSIONS: Urinary levels of cortisol, epinephrine, and norepinephrine are significantly increased after a major burn. Early hypercortisolemia is associated with increased duration of severe infection. Persistent hypercortisolemia is associated with increases in both infection rates and duration of severe infection.

Pathophysiologic response to severe burn injury.

OBJECTIVE: To improve clinical outcome and to determine new treatment options, we studied the pathophysiologic response postburn in a large prospective, single center, clinical trial. SUMMARY BACKGROUND DATA: A severe burn injury leads to marked hypermetabolism and catabolism, which are associated with morbidity and mortality. The underlying pathophysiology and the correlations between humoral changes and organ function have not been well delineated. METHODS: Two hundred forty-two severely burned pediatric patients [>30% total body surface area (TBSA)], who received no anabolic drugs, were enrolled in this study. Demographics, clinical data, serum hormones, serum cytokine expression profile, organ function, hypermetabolism, muscle protein synthesis, incidence of wound infection sepsis, and body composition were obtained throughout acute hospital course. RESULTS: Average age was 8 +/- 0.2 years, and average burn size was 56 +/- 1% TBSA with 43 +/- 1% third-degree TBSA. All patients were markedly hypermetabolic throughout acute hospital stay and had significant muscle protein loss as demonstrated by a negative muscle protein net balance (-0.05% +/- 0.007 nmol/100 mL leg/min) and loss of lean body mass (LBM) (-4.1% +/- 1.9%); P < 0.05. Patients lost 3% +/- 1% of their bone mineral content (BMC) and 2 +/- 1% of their bone mineral density (BMD). Serum proteome analysis demonstrated profound alterations immediately postburn, which remained abnormal throughout acute hospital stay; P < 0.05. Cardiac function was compromised immediately after burn and remained abnormal up to discharge; P < 0.05. Insulin resistance appeared during the first week postburn and persisted until discharge. Patients were hyperinflammatory with marked changes in IL-8, MCP-1, and IL-6, which were associated with 2.5 +/- 0.2 infections and 17% sepsis. CONCLUSIONS: In this large prospective clinical trial, we delineated the complexity of the postburn pathophysiologic response and conclude that the postburn response is profound, occurring in a timely manner, with derangements that are greater and more protracted than previously thought.

Upper airway mucus deposition in lung tissue of burn trauma victims.

Previous study in an ovine model of smoke inhalation and burn (S + B) injury has shown distal migration of upper airway mucus. This study examines the localization of an upper airway gland specific mucus, mucin 5B (MUC5B) in lung autopsy tissues of burn-only injury and in victims of S + B injury. We hypothesize that victims with S + B injury would exhibit increased distal migration of MUC5B than that seen in victims of burn-only injury. Autopsy lung tissue from victims of burn injury alone (n = 38) and combined S + B injury (n = 22) were immunostained for MUC5B. No normal lung tissues were included in the study. Semiquantitative analysis of the extent of MUC5B in bronchioles and parenchyma was performed on masked slides. Irrespective of injury conditions, all victims showed MUC5B in bronchioles. Mucin 5B was seen in the parenchyma except in two burn victims. No statistically significant difference was seen in the mean bronchiolar and parenchyma MUC5B scores between S + B and burn-only victims (P > 0.05). No strong statistical correlation of MUC5B scores with days postinjury or to the number of ventilatory days was evident. The percentage of pneumonia, identified histologically, was also similar between study groups. This study did not confirm our results in an ovine model of S + B injury. In contrast, virtually all pediatric burn victims, regardless of concomitant inhalation injury, showed MUC5B in their bronchioles and parenchyma. Increased mucus synthesis and/or impaired mucociliary function may contribute to the pulmonary pathophysiology associated with burn injury.

Lipid metabolism in diet-induced obese rabbits is similar to that of obese humans.

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.

Resistance exercise increases human skeletal muscle AS160/TBC1D4 phosphorylation in association with enhanced leg glucose uptake during postexercise recovery.

Akt substrate of 160 kDa (AS160/TBC1D4) is associated with insulin and contraction-mediated glucose uptake. Human skeletal muscle AS160 phosphorylation is increased during aerobic exercise but not immediately following resistance exercise. It is not known whether AS160 phosphorylation is altered during recovery from resistance exercise. Therefore, we hypothesized that muscle AS160/TBC1D4 phosphorylation and glucose uptake across the leg would be increased during recovery following resistance exercise. We studied 9 male subjects before, during, and for 2 h of postexercise recovery. We utilized femoral catheterizations and muscle biopsies in combination with indirect calorimetry and immunoblotting to determine whole body glucose and fat oxidation, leg glucose uptake, muscle AMPKalpha2 activity, and the phosphorylation of muscle Akt and AS160/TBC1D4. Glucose oxidation was reduced while fat oxidation increased ( approximately 35%) during postexercise recovery (P

Aging does not impair the anabolic response to a protein-rich meal.

BACKGROUND: Sarcopenia is a debilitating condition afflicting the elderly that may be facilitated by insufficient or ineffectual intake of dietary protein. We previously showed that free-form essential amino acids acutely stimulate muscle protein synthesis in both the young and the elderly. However, the ability of an actual protein-rich food to stimulate anabolism in the young and the elderly has not been explored. OBJECTIVE: We aimed to characterize changes in plasma amino acid concentrations and to quantify muscle protein synthesis in healthy young (41 +/- 8 y old; n = 10) and elderly (70 +/- 5 y old; n = 10) persons after ingestion of a 113-g (4-oz) serving of lean beef. DESIGN: Venous blood samples and vastus lateralis muscle biopsy samples were obtained during a primed (2.0 mumol/kg) constant infusion (0.08 mumol.kg(-1).min(-1)) of l-[ring-(13)C(6)] phenylalanine. Plasma amino acid concentrations were measured and a mixed-muscle fractional synthesis rate (FSR) was calculated during the premeal period and for 5 h after beef ingestion. RESULTS: Mixed-muscle FSR increased by approximately 51% in both the elderly (mean +/- SE measurements: 0.072 +/- 0.004%/h and 0.108 +/- 0.006%/h before and after the meal, respectively) and the young (0.074 +/- 0.005%/h and 0.113 +/- 0.005%/h before and after the meal, respectively) after beef ingestion (P < 0.001). Plasma amino acid concentrations peaked at approximately 100 min after beef ingestion in both age groups but were substantially higher in the elderly (2185 +/- 134 nmol/mL compared with 1403 +/- 96 nmol/mL; P < 0.001). CONCLUSION: Despite differences in the concentration of amino acids in the plasma precursor pool, aging does not impair the ability to acutely synthesize muscle protein after ingestion of a common protein-rich food.

Pamidronate preserves bone mass for at least 2 years following acute administration for pediatric burn injury.

We have previously shown that pamidronate, when given within 10 days of burn injury, preserves lumbar spine bone mineral content from admission to discharge in 6-8 weeks and at 6 months increases both lumbar spine and total body bone mineral content (BMC) over placebo. We followed patients unblinded after 6 months every 3 months up to 2 years post-burn to see if the effects of pamidronate were sustained. Additionally, we assessed bone remodeling at 1 year post-burn by iliac crest bone biopsy. We enrolled 57 subjects who were initially randomized to pamidronate (n=32) and placebo (n=25). After 2 years, 21 subjects (pamidronate=8, placebo=13) remained. Analysis of bone densitometry by dual energy X-ray absorptiometry revealed an effect of both treatment (p<0.012 for total body BMC, p<0.001 for lumbar spine BMC, p<0.014 for lumbar spine bone area and p<0.003 for lumbar spine bone density (BMD)) and time (p<0.0003 on total body BMC, p<0.001 on lumbar spine BMC, p<0.001 on lumbar spine bone area, and no significant difference on lumbar spine BMD). There was no interaction between treatment and time. Results for bone histomorphometry revealed no effect of treatment on either static or dynamic parameters but did show an effect of time on osteoid area (p=0.004, surface p<0.001, and width, p<0.001). We conclude that acute administration of pamidronate resulted in sustained therapeutic effect on bone and that this type of administration may serve as a useful adjunct to other therapies in the preservation and augmentation of bone mass following severe burns.

Serum cytokine differences in severely burned children with and without sepsis.

The aim was to determine whether serum cytokine profiling early after burn can be used to identify patients at high risk of developing and subsequently dying of sepsis. A case series study was designed to determine whether serum cytokine profiling allows identification of patients at highest risk of developing and dying of sepsis at the time of hospital admission. All patients were treated according to the standard of burn care at our facility. Forty-four children (1-19 years old) with more than 40% of total body surface area and admitted within 7 days postburn were studied. None had infections or sepsis at the time of admission. Serum was collected before the first operation, and concentrations of 17 cytokines were measured. Diagnosis of sepsis was made at autopsy with identification of the pathogen. Fifteen patients developed sepsis and died, whereas 29 patients did not develop sepsis and survived. Significant elevations in serum interleukin (IL) 6, IL-8, IL-10, granulocyte-monocyte colony-stimulating factor, interferon gamma (IFN-gamma), tumor necrosis factor (TNF), and IL-12 p70 were found at the time of admission of patients who subsequently developed and died of sepsis when compared with burned patients who did not develop sepsis (P < 0.05). Multiple logistic regression analysis revealed that patients with a combination of elevated IL-6 and IL-12 p70 and lower TNF had an elevated risk of dying of sepsis. Serum IL-6, IL-8, IL-10, granulocyte-monocyte colony-stimulating factor, IFN-gamma, TNF, and IL-12 p70 are expressed differently in patients who die of sepsis versus those who never become septic. In addition, serum IL-6, IL-12 p70, and TNF can be used to identify burned patients who are at high risk of death from sepsis.

The effects of gammahydroxybutyrate on hypermetabolism and wound healing in a rat model of large thermal injury.

BACKGROUND: Growth hormone (GH) improves wound healing and ameliorates pediatric postburn tissue catabolism associated with deficient endogenous GH/IGF-1 levels. Expense, parenteral administration, and compliance have limited widespread usage. Gammahydroxybutyrate (GHB), an upstream neuromodulatory gamma-amino butyric acid (GABA) derivative, is known to increase slow wave sleep and stimulate endogenous GH secretion. In this study, improvement in GH levels in turn has been shown to accelerate wound healing. METHODS: Body composition in male Sprague-Dawley rats with > or =40% total body surface area scald burn, receiving incremental GHB doses orally, was assessed by Dual Energy X-Ray Absorptiometry. Serum GH and IGF-1 levels were measured. Wound cross sections were scored semiquantitatively for wound healing variables. RESULTS: Incremental elevation in GH and IGF-1 were associated with significantly improved wound edge epithelialization and cell-layer thickness at high doses (p < 0.005). However, body composition was similar to that of burned controls. CONCLUSIONS: GHB sufficiently elevated serum GH and IGF-1 levels to significantly improve epithelialization rates and layer thickness at high doses. Substantially greater elevations of serum GH and IGF-1 levels are required in the rat burn model than for humans. GHB may improve postburn hypermetabolism in humans by elevating endogenous GH levels, though only improved epithelialization was demonstrated in this study.

Assessment of adverse events in the demise of pediatric burn patients.

BACKGROUND: Given the contention that survival is to be expected from even the most severely burned child, then, intuitively, at least some pediatric burn victims die because of suboptimal care. The purpose of this study is to assess the impact of any adverse events that may have contributed to the death of burned children. METHODS: Four surgeons with specialty training in pediatric burn care reviewed the clinical course and autopsy findings of 71 burned children who died after admission to a burn center during a 10-year interval. Reviewers were asked to determine the predominant factor or factors contributing to each child's demise and to assess the significance of any deviations from optimal care. RESULTS: For the 10 years under review, overall mortality for all pediatric burns was 2.4%. Of these deaths, 25% had burns encompassing less than 50% body surface area. The reviewers identified lung damage as the most frequent cause of death, which was deemed largely unpreventable. Conversely, hypovolemia related to inadequate prehospital fluid resuscitation and failure to obtain and maintain a patent airway were considered the second and third most common factors in a child's death and deemed preventable under ideal circumstances. CONCLUSIONS: This review implies that deficiencies in health care contribute to the demise of many burned children. The most notable areas for improvement are in fluid resuscitation and airway control. This suggests that quality assurance and educational initiatives to improve these aspects of care may have the greatest impact on further improving survival of burned children.

A multicompartmental model of in vivo adipose tissue glycerol kinetics and capillary permeability in lean and obese humans.

Lipolysis of adipose tissue triglycerides releases glycerol. Twenty-four volunteers, of whom 6 were obese and 13 were women, received a primed-constant infusion of 2H5-glycerol for 120 min during postabsorptive steady-state conditions. Arterial, abdominal venous, and interstitial (microdialysis) samples were taken, and a four-compartment model was applied to assess subcutaneous abdominal adipose tissue glycerol kinetics. Adipose tissue blood flow was measured using 133Xe washout. Venous glycerol concentrations (median 230 micromol/l [interquartile range 210-268]) were consistently greater than those of arterial blood (69.1 micromol/l [56.5-85.5]), while glycerol isotopic enrichments (tracer-to-tracee ratio) were greater in arterial blood (8.34% [7.44-10.1]) than venous blood (2.34% [1.71-2.69], P < 0.01). Microdialysate glycerol enrichment was 1.44% (1.11-1.79), indicating incomplete permeability of glycerol between capillary blood and interstitium. Calculated interstitial glycerol concentrations were between 270 micromol/l (256-350) and 332 micromol/l (281-371) (examining different boundary conditions). The calculated capillary diffusion capacity (ps) was between 2.21 ml . 100 g tissue(-1) . min(-1) (1.31-3.13) and 3.09 ml . 100 g tissue(-1) . min(-1) (1.52-4.90) and correlated inversely with adiposity (Rs< or = -0.45, P < 0.05). Our results support previous estimates of interstitial glycerol concentration within adipose tissue and reveal capillary diffusion capacity is reduced in obesity.

Effects of hemorrhage and lactated Ringer's resuscitation on coagulation and fibrinogen metabolism in swine.

Hemorrhagic coagulopathy is a significant complication after traumatic injury, and much of the underlying mechanism remains unclear. We investigated the changes in fibrinogen metabolism and coagulation after a moderate hemorrhage and resuscitation. Pigs of either sex (weight, 40.9+/-0.8 kg) were anesthetized and instrumented with arterial and venous catheters and a thermodilution cardiac output catheter. Pigs were randomized into control (C; n=6), hemorrhage (H; n=6), and hemorrhage and resuscitation (H-LR; n=6) groups. Hemorrhage was induced by bleeding 35% of total blood volume for 30 min in H and H-LR groups. Resuscitation in H-LR group was performed using lactated Ringer's solution (LR) at 3 times the bled volume for 30 min. Fibrinogen metabolism was quantified using a primed constant infusion of 1-13C-phenylalanine (6 h) and d5-phenylalanine (4 h) and subsequent analysis by gas chromatograph-mass spectrometry, together with measurements of hemodynamics (hourly) and coagulation by thromboelastography (at baseline and 4 h after hemorrhage and resuscitation). Hemorrhage caused decreases in arterial pH and base excess, and an increase in arterial lactate content. Fluid resuscitation corrected these changes toward normal levels. Fibrinogen level was unchanged in C and decreased to 76%+/-4% in H and to 73%+/-3% in H-LR (both P<0.05, compared with baseline) after hemorrhage and resuscitation. Fibrinogen breakdown was increased from 3.0+/-0.4 mg kg-1 h-1 in C to 5.4+/-0.6 mg kg-1 h-1 in H and to 5.6+/-0.5 mg kg-1 h-1 in H-LR (both P<0.05, compared with control), but synthesis was unchanged. The clotting reaction time was unchanged in C and shortened to 93%+/-3% in H and to 91%+/-1% in H-LR (both P<0.05, compared with baseline). We conclude that hemorrhagic shock caused accelerated fibrinogen breakdown and coagulation. The LR resuscitation reduced tissue hypoxia indexes but did not affect the changes in fibrinogen metabolism and coagulation from hemorrhage. Thus, effective treatment of hemorrhage should include combining standard-of-care resuscitation with interventions to correct alterations in coagulation.