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:To identify signature genes that help distinguish (1) sepsis from non-infectious causes of systemic inflammatory response syndrome, (2) between Gram-positive and Gram-negative sepsis. Experiment Overall Design: A total of 70 critically ill patients (46 sepsis and 24 control) were enrolled in a single-centre observational study. Gene-expression profiling was performed using Affymetrix microarray (U133plus2) with 54,675 transcript. Data was divided into a training set (n=35) and a validation set (n=35). A molecular signature was developed in the training set and was then validated in the validation set.
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:A microarray analysis involving whole blood samples isolated from critically ill patients in the medical intensive care unit at Brigham and Women's Hospital. Four groups of intubated subjects undergoing mechanical ventilation were recruited for the study: those with sepsis alone (Sepsis), those with sepsis + ARDS (se/ARDS), those with SIRS (SIRS), and those whithout sepsis, SIRS, or ARDS (untreated). Blood was obtained from patients on the day of admission (day 0) and 7 days later. RNA was isolated from the whole blood samples and microarrays were prepared to determine differential gene expression between the four groups. Total RNA obtained from whole blood samples of critically ill patients
Project description:Clinical study of critically ill patients with sepsis and sepsis-related ARDS with whole blood RNA collected within the first 24 hours of admission Goal of the study was to determine whether biologically relevant genes were identified to be differentially expressed genes in patients with sepsis alone and sepsis with ARDS Prospective observational study, case cohort design
Project description:Clinical study of critically ill patients with sepsis and sepsis-related ARDS with whole blood RNA collected within the first 24 hours of admission Goal of the study was to determine whether biologically relevant genes were identified to be differentially expressed genes in patients with sepsis alone and sepsis with ARDS
Project description:To identify signature genes that help distinguish (1) sepsis from non-infectious causes of systemic inflammatory response syndrome, (2) between Gram-positive and Gram-negative sepsis. Keywords: Class prediction study
Project description:Genome-wide gene expression profiling of whole blood leukocytes in critically ill patients with sepsis or non-infectious disease has been used extensively in search of diagnostic biomarkers, as well as prognostic signatures reflecting diseases severity and outcome. Through technological advances in genomics it has become clear that transcription is not limited to protein-coding regions of the genome. Here, we describe a comprehensive analysis of RNA expression in blood leukocytes of critically ill patients with sepsis, a non-infectious condition and healthy subjects
Project description:We here sought to firstly identify differentially abundant circulatory small non-coding RNA in critically ill patients with sepsis due to community-acquired pneumonia (CAP) patients as compared to healthy subjects, and secondly delineate those putatively targeted cellular pathways.