Project description:Objective: It is unclear whether the host response of gram-positive sepsis differs from gram-negative sepsis at a transcriptome level. Using microarray technology, we compared the gene-expression profiles of gram-positive sepsis and gram-negative sepsis in critically ill patients. Design: A prospective cross-sectional study. Setting: A 20-bed general intensive care unit of a tertiary referral hospital. Patients: Seventy-two patients admitted to the intensive care unit. Interventions: Intravenous blood was collected for leukocyte separation and RNA extraction. Microarray experiements were then performed examing the expression level of 19,232 genes in each sample. Measurements and Main Results: There was no difference in the expression profile between gram-positive and gram-negative sepsis. The finding remained unchanged even when genes with lower expression level were included or after statistical stringency was lowered. There were, however, ninety-four genes differentially expressed between sepsis and control patients. These genes included those involved in immune regulation, inflammation and mitochondrial function. Hierarchical cluster analysis confirmed that the difference in gene expression profile existed between sepsis and control patients, but not between gram-positive and gram-negative patients. Conclusion: Gram-positive and gram-negative sepsis share a common host response at a transcriptome level. These findings support the hypothesis that the septic response is non-specific and is designed to provide a more general response that can be elicited by a wide range of different micro-organisms. Keywords: disease state analysis, gram-positive sepsis, gram-negative sepsis
Project description:Objective: It is unclear whether the host response of gram-positive sepsis differs from gram-negative sepsis at a transcriptome level. Using microarray technology, we compared the gene-expression profiles of gram-positive sepsis and gram-negative sepsis in critically ill patients. Design: A prospective cross-sectional study. Setting: A 20-bed general intensive care unit of a tertiary referral hospital. Patients: Seventy-two patients admitted to the intensive care unit. Interventions: Intravenous blood was collected for leukocyte separation and RNA extraction. Microarray experiements were then performed examing the expression level of 19,232 genes in each sample. Measurements and Main Results: There was no difference in the expression profile between gram-positive and gram-negative sepsis. The finding remained unchanged even when genes with lower expression level were included or after statistical stringency was lowered. There were, however, ninety-four genes differentially expressed between sepsis and control patients. These genes included those involved in immune regulation, inflammation and mitochondrial function. Hierarchical cluster analysis confirmed that the difference in gene expression profile existed between sepsis and control patients, but not between gram-positive and gram-negative patients. Conclusion: Gram-positive and gram-negative sepsis share a common host response at a transcriptome level. These findings support the hypothesis that the septic response is non-specific and is designed to provide a more general response that can be elicited by a wide range of different micro-organisms. The study included seventy-two critically ill patients admitted to the intensive care unit (ICU) of Nepean Hospital, Sydney, Australia. Of these, fifty-five patients were diagnosed to have sepsis, as confirmed by microbiological culture. The remaining seventeen patients did not have sepsis and were therefore used as controls. The study was approved by the hospital ethics committee and informed consent was obtained from all patients or their relatives. Patient Samples. Whole blood was taken from each patient on admission to ICU. Neutrophils were separated from whole blood using density-gradient separation with Ficoll-PaqueP P(Amersham). Subsequent neutrophil RNA extraction was performed using guanidinium thiocyanate (Ambion). Microarray Experiment. The neutrophil RNA was converted to cDNA, fluorescently labeled and hybridized to its complimentary sequences on the microarray (Invitrogen). The fluorescent signals on each micrroarray were captured using the GenePix 4000B laser scanner (Axon Instruments). Expression level of each gene was represented by the intensity of its fluorescent signal. Data Extraction. All signal intensity values were processed using background-subtraction method. Prior to analysis, all values were log-transformed and normalized by fitting a print-tip group Lowess curve. Normalization minimizes bias due to dye chemistry, signal intensity or location of a gene on the array. It ensures the detection of genes that are truly differentially expressed, instead of those caused by experimental artifacts or variation in the hybridization process. After normalization, genes that had more than 50% of data missing were removed. We then selected genes that had at least 80% of the data showing two-fold changes from the geneâs median values. After filtering, 1617 genes were available for further analysis.
Project description:#G017 Burn/Trauma Study. This is a Glue Grant Study comparison between gene expression analyses performed in eight trauma/burn subjects using either a buffy coat isolation of whole blood or using the PAXgene system Keywords: other
Project description:Animal experiments were performed with male Sprague-Dawley rats (Charles River Laboratories, Boston, MA) weighing 150 ? 200 grams. All experimental protocols used in this study were approved by the Subcommittee on Research Animal Care, Massachusetts General Hospital. Rats were individually housed in a temperature-controlled (25oC) and light-controlled room (12h light-dark cycle) and allowed to adjust to their new surroundings for at least 5 days prior to the experiment. Water and rat chow were provided ad libitum to the animals. On the day of the treatment, the animals were randomly divided into two groups, burned and sham-burned. The burn injury consisted of a full-skin-thickness scald burn of the dorsum, calculated to be ~ 20% of the rat?s total body surface area (TBSA), induced by immersing the designated area in boiling water for 10 s (45). Rats were resuscitated with an intra-peritoneal injection of sterile saline solution (1.5 mL/Kg body weight/% TBSA) immediately after burn. The mortality rate of this treatment was negligible. At each time point (1, 2, 4, and 7d), three animals belonging to each group were sacrificed, the liver and serum collected, and stored at ?80oC after being inflicted with 20% TBSA burn injury. Sham-burn rats (n=3) considered as the control were treated identically except that they were immersed into a 37oC water bath and immediately sacrificed to collect the livers. Keywords = Burn Liver microarray genechip time course Keywords: time-course
Project description:Burn wound blister fluid is a valuable matrix for understanding the biological pathways associated with burn injury. In this study, 152 blister fluid samples collected from paediatric burn wounds at two different hospitals were analysed using mass spectrometry proteomic techniques. The protein abundance profile at different days post-burn indicated that there were more proteins associated with cellular damage/repair in the first 24 hours, whereas after this point there were more proteins associated with antimicrobial defence and inflammation. The inflammatory proteins persisted at a high level in the blister fluid for more than 7 days. This may indicate that removal of burn blisters prior to two days post-burn is optimal to prevent excessive or prolonged inflammation in the wound environment. Additionally, many proteins associated with the neutrophil extracellular trap (NET) pathway were increased post-burn, further implicating NETs in the post-burn inflammatory response. NET inhibitors may therefore be a potential treatment to reduce post-burn inflammation and coagulation pathology and enhance burn wound healing outcomes.
Project description:Burn injury remains a major clinical challenge to both survival and to quality of life. Its progressive, aberrant inflammation underlies the lethal dysfunction of various organs and the pain it induces is excruciating and notoriously difficult to manage. While it is known that burn injury’s complex local and disseminating pathology is orchestrated from the burned tissue, few studies have sought to characterise the local signalling environment. An enhanced understanding of the local and acutely temporally-dynamic processes defining burn injury and its progression is required for the development of novel therapeutic interventions. Microdialysis was used as an interstitial sampling technique, conducted over three hours post-burn. Samples were analysed by metabolomics and a multiplex cytokine immunoassay. Next-Generation sequencing libraries of the burn and control microdialysis sites were prepared to measure transcriptional changes potentially underlying the interstitial profile characterising burn injury.