| 1. |
- Hedtjärn, Maj, 1973, et al.
(författare)
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Global gene expression in the immature brain after hypoxia-ischemia
- 2004
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Ingår i: J Cereb Blood Flow Metab. ; 24:12, s. 1317-32
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Tidskriftsartikel (refereegranskat)abstract
- Ischemia induces a complex response of differentially expressed genes in the brain. In order to understand the specific mechanisms of injury in the developing brain, it is important to obtain information on global changes in the transcriptome after neonatal hypoxia-ischemia. In this study, oligonucleotide arrays were used to investigate genomic changes at 2, 8, 24, and 72 hours after neonatal hypoxia-ischemia, which was induced in 9-day-old mice by left carotid artery ligation followed by hypoxia (10% O2). In total, 343 genes were differentially expressed in cortex, hippocampus, thalamus, and striatum 2 to 72 hours after hypoxia-ischemia, when comparing ipsilateral with contralateral hemispheres and with controls, using the significance analysis for microarrays. A total of 283 genes were upregulated and 60 were downregulated, and 94% of the genes had not previously been shown after neonatal hypoxia-ischemia. Genes related to transcription factors and metabolism had mostly upregulated transcripts, whereas most downregulated genes belonged to the categories of ion and vesicular transport and signal transduction. Genes involved in transcription, stress, and apoptosis were induced early after the insult, and many new genes that may play important roles in the pathophysiology of neonatal hypoxia-ischemia were identified.
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| 2. |
- Hedtjärn, Maj, 1973, et al.
(författare)
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Inflammatory gene profiling in the developing mouse brain after hypoxia-ischemia
- 2004
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Ingår i: J Cereb Blood Flow Metab. ; 24:12, s. 1333-51
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Tidskriftsartikel (refereegranskat)abstract
- Brain ischemia triggers an inflammatory reaction that progresses for days to weeks and seems to have a role in secondary progression of injury. Inflammation induces a complex pattern of signaling molecules with partly contradictory actions, and the responses may be different in the immature and adult brain. The authors characterized the global inflammatory gene expression in the developing brain as a first step toward understanding the protective and deleterious effects of inflammation after hypoxia-ischemia. Oligonucleotide arrays were used to investigate inflammatory genes in cortex, hippocampus, thalamus, and striatum at 2, 8, 24, and 72 hours after hypoxia-ischemia, which was induced in 9-day-old mice by left carotid artery ligation followed by hypoxia. After hypoxia-ischemia, 148 inflammatory genes were differentially expressed. More than 97% of the genes were upregulated and 93% had not previously been reported after hypoxia-ischemia in the immature brain. The results indicate that microglia/macrophages, T- and B-cells, NK-cells, mast cells, dendritic cells, and polymorphonuclear leukocytes may participate in the response to hypoxia-ischemia. In addition, novel cytokines/chemokines, complement-related, interferon-regulated, components of the TIR/nuclear factor-kappaB pathway, and a number of immunomodulatory genes were induced. Several of these genes may of pathophysiologic significance after neonatal hypoxia-ischemia.
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| 3. |
- Hedtjärn, Maj, 1973
(författare)
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Inflammatory response in the immature brainafter hypoxia-ischemia. Application of microarray and transgenic technology
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hypoxic-ischemic (HI) brain injury remains a common problem encountered during theneonatal period, and it is a major cause of perinatal mortality and long term neurologicalimpairments. After HI, an inflammatory reaction is elicited in the brain, which is believedto contribute to the secondary progression of brain injury.The aim of this thesis was to investigate the inflammatory response and its possiblepathophysiological role after HI in the immature brain.Using a model of cerebral HI in 7-day-old rats, the expression of caspase-1 and IL-18 wasinvestigated by RT-PCR, Western blot and immunohistochemistry and the expression ofIL-1beta by ELISA and immunohistochemistry at various time points after HI. Theinvolvement of different members of the IL-1 family in the development of HI injury wasinvestigated in 9-day-old mice by using different transgenic mice and comparing theirsusceptibility to HI injury with wild-type mice. Global changes in gene expression atvarious time points after HI was investigated with Affymetrix Gene Chips (MG-U74Av2).After HI, caspase-1 and IL-18 mRNA and protein were increased in a similar pattern,starting at 1 day of reperfusion and reaching maximal levels 14 days after the insult. IL-1betawas expressed maximally at 8h after HI, when a 7-fold increase was detected comparedwith contralateral hemispheres. IL-18 deficient mice showed reduced injury after HIcompared with wild-type mice in both gray (-21% overall injury) and white matter(remaining amount MBP and NF was 92% and 78% higher, respectively, in IL-18-deficient compared with control mice). Mice deficient for IL-1beta or the combination ofIL-1alfabeta showed no reduced injury after HI compared with wild-type. When studyingchanges in global gene expression, a total of 491 genes were differentially expressed 2h to72h after HI, using the Significance analysis of microarray (SAM) statistical program withthe following criteria (FDR <10%, fold change 1.5). More than 90% of the differentiallyexpressed genes were previously unreported after HI in the immature brain. Real-timePCR confirmed the expression of 11 upregulated genes. Of the differentially expressedgenes, 29% belonged to the group of immune-inflammatory related genes. Our dataindicate that microglia/macrophages, T- and B- cells, NK-cells, mast cells, dendritic cells,and polymorphonuclear leukocytes may participate in the response to HI. In addition,novel cytokines/chemokines, complement-related, IFN-regulated, components of theTIR/NF-kB pathway and a number of immuno-modulatory genes were induced.In conclusion, the results from this thesis indicate that IL-18 is involved in HI injury inboth gray and white matter, while IL-1 does not seem to be a contributor. In addition,this study has provided novel information about changes in inflammatory gene expressionafter HI, and several inflammatory mediators which may be of pathophysiologicalsignificance after neonatal HI have been identified.
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