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Series GSE6535 Query DataSets for GSE6535
Status Public on Dec 01, 2007
Title Critically ill patients with either gram-positive sepsis or gram-negative sepsis
Organism Homo sapiens
Experiment type Expression profiling by array
Summary 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
Overall design 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 gene’s median values. After filtering, 1617 genes were available for further analysis.
Contributor(s) Tang BM
Citation(s) 18379237, 23036193
Submission date Dec 14, 2006
Last update date Aug 23, 2019
Contact name Benjamin Man Piu Tang
Phone 61415614883
Organization name Nepean Hospital
Department Intensive Care Medicine
Street address 12/29 Cook Street
City Glebe
State/province NSW
ZIP/Postal code 2037
Country Australia
Platforms (1)
GPL4274 NHICU Human 19K v1.0
Samples (72)
GSM151369 Control Patient C1
GSM151370 Control Patient C2
GSM151371 Control Patient C3
BioProject PRJNA98813

Download family Format
SOFT formatted family file(s) SOFTHelp
MINiML formatted family file(s) MINiMLHelp
Series Matrix File(s) TXTHelp

Supplementary file Size Download File type/resource
GSE6535_RAW.tar 146.4 Mb (http)(custom) TAR (of GPR)
Raw data provided as supplementary file

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