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Objective: The purpose of this study was to identify gene-expression changes in leg muscle for up to 24 months after a severe thermal injury., Summary Background Data: Hypermetabolism associated with severe burns was thought to cease with wound healing and closure. It has been recently shown that hypermetabolism does not completely resolve after healing, and muscle catabolism continues after hospital discharge; however, just how long after discharge has not been established., Methods: : Six children, admitted to our hospital within 1 week after injury, were studied. Patients ranged in age from 3 to 18 years, with flame or scald burns covering more than 40% of their body surface area. At 1.5, 6, 12, 18, and 24 months postburn, a biopsy of the vastus lateralis muscle was taken and snap frozen at -80 degrees C. Total RNA was isolated and in vitro transcribed and hybridized to HG-U95 Av.2 Affymetrix arrays. The images were scanned and analyzed using Affymetrix GeneChip Analysis Suite 5.2 and dChip programs. Using 1 to 7 days after injury as baseline, comparisons were made of expression profiles at the various time intervals after injury., Results: When comparisons are made to nonburned children, 38 genes were significantly altered at 1.5 months, 10 genes remained altered at 6 months, 4 remained altered at 12 months, and 2 at 18 months. No differences could be shown at 24 months. Western blot analysis of beta-2 microglobulin and myosin light chain was used to corroborate the microarray data., Conclusions: Gene changes can be identified for up to 18 months after burn but not at 24 months. These gene changes may provide information concerning what genes in skeletal muscle contribute to recovery from burn trauma.

Background: Thermal injury is associated with a pronounced catabolic response in skeletal muscle. This study identifies gene expression changes in skeletal muscle of thermally injured girls and boys using high-density oligonucleotide arrays., Methods: Six burned children with a mean age of 8.3 +/- 1.3 years and TBSA burn size covering 51 +/- 6% admitted to our hospital with in 48 h of injury and six cleft lip and cleft palate patients were studied. Total RNA was isolated, in vitro transcribed, and hybridized to HG-U95 Av.2 Affymetrix arrays. Messenger RNA expression patterns of controls and burn patients were compared using Affymetrix GeneChip Analysis Suite 5.2 and dChip., Results: Statistical analysis of the 12,625 genes on each array showed a significant increase in the expression of 77 genes in burn children and a decrease in 21 genes when compared to controls (P < 0.05). We found three genes in burned males and two genes in burned females with decreased expression in muscle compared to controls. Chromosomes 1, 2, 7, 12, and 16 showed genes with increased expression in muscle from burned children, while chromosomes 3, 7, 8, 19, and 22 had genes with decreased expression. Categories of genes affected were related to metabolism, proliferation, transcription/translation, immune response, stress response, angiogenesis, and signal transduction., Conclusions: Genes that are differentially expressed in skeletal muscle of burned children, but whose function in muscle is unknown, include those related to various transcription factors and those known to encode proteins involved in signaling pathways. Further analysis is required to achieve the ultimate goal of making functionally relevant conclusions about the molecular pathology of burn injury.

The liver plays an important role in a severe thermal injury by modulating immune function, inflammatory processes and the acute phase response, which are an orchestrated attempt to restore homeostasis. Using high-density oligonucleotide arrays, we examined the gene expression profile in the livers of rats between 2 and 240 h after a 40% total body surface area (TBSA) burn. Alterations in gene expression unique to a thermal injury were identified. Approximately 39 genes out of 8700 genes on each array across all the time points showed a significant change in expression patterns. Real time reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses verified significant changes in early growth response-1 (Egr-1) messenger RNA (mRNA) and protein levels corresponding to the array data. Significant increases in serum levels of alpha-2-macroglobulin that correspond to changes in its mRNA levels were observed at 6 and 24 h after burn, p<0.05. The genomic pattern for liver in the hypermetabolic phase after the burn injury involves transcription factors, stress and inflammatory responses, cytoskeletal and extracellular matrix modifications, and regulation of cell proliferation and differentiation. During the initial phase of thermal injury gene expression profiles in the liver may provide some insight into how cellular protection mechanisms and systemic hypermetabolism are initiated and controlled. The genome wide changes observed may provide a rational therapeutic strategy to improve burn care.

Objective: To analyze gene expression patterns in skeletal muscle from burned children., Summary Background Data: Analysis of gene expression patterns in skeletal muscle from burned children can help provide a fundamental understanding of muscle wasting at the molecular level. This study is the first to use such an approach in burned children receiving anabolic treatment., Methods: Children who received 0.1 mg/kg oxandrolone twice a day (n = 7) were compared to placebo (n = 7). Net protein balance was determined before and after treatment with oxandrolone. Total RNA, extracted from muscle biopsies obtained from burned children age 3 to 18 years, was purified, reverse transcribed, and biotinylated cRNA hybridized to the human high-density oligonucleotide array (U95Av2). Western blot analysis verified the mRNA changes at their protein level., Results: DNA microarray analysis showed two genes significantly changed in muscle from burned children receiving placebo, while the expression of 21 genes was altered with oxandrolone. Muscle net protein balance increased with oxandrolone treatment compared to placebo., Conclusions: DNA microarray technology will help identify molecular changes that can serve as targets for new therapies to attenuate muscle wasting in severely burned children and thus improve recovery and early rehabilitation.

The events occurring early in the burn wound trigger a sequence of local and systemic responses that influence cell and tissue survival and, consequently, wound healing and recovery. Using high-density oligonucleotide arrays we identified gene expression patterns in skin samples taken from a region of injury in the burn rat model. The associated genomic events include the differential expression of genes involved in cell survival and death, cell growth regulation, cell metabolism, inflammation, and immune response. The functional gene cluster detected and their time appearance matched the time sequence known to occur in burn wound healing.