The effect of extracellular glutamate release on repetitive transient ischemic injury in global ischemia model.

During operations, neurosurgeons usually perform multiple temporary occlusions of parental artery, possibly resulting in the neuronal damage. It is generally thought that neuronal damage by cerebral ischemia is associated with extracellular concentrations of the excitatory amino acids. In this study, we measured the dynamics of extracellular glutamate release in 11 vessel occlusion (VO) model to compare between single occlusion and repeated transient occlusions within short interval. Changes in cerebral blood flow were monitored by laser-Doppler flowmetry simultaneously with cortical glutamate level measured by amperometric biosensor. From real time monitoring of glutamate release in 11 VO model, the change of extracellular glutamate level in repeated transient occlusion group was smaller than that of single occlusion group, and the onset time of glutamate release in the second ischemic episode of repeated occlusion group was delayed compared to the first ischemic episode which was similar to that of single 10 min ischemic episode. These results suggested that repeated transient occlusion induces less glutamate release from neuronal cell than single occlusion, and the delayed onset time of glutamate release is attributed to endogeneous protective mechanism of ischemic tolerance.

A comprehensive profile of DNA copy number variations in a Korean population: identification of copy number invariant regions among Koreans.

To examine copy number variations among the Korean population, we compared individual genomes with the Korean reference genome assembly using the publicly available Korean HapMap SNP 50 k chip data from 90 individuals. Korean individuals exhibited 123 copy number variation regions (CNVRs) covering 27.2 mb, equivalent to 1.0% of the genome in the copy number variation (CNV) analysis using the combined criteria of P value (P<0.01) and standard deviation of copy numbers (SD>or= 0.25) among study subjects. In contrast, when compared to the Affymetrix reference genome assembly from multiple ethnic groups, considerably more CNVRs (n=643) were detected in larger proportions (5.0%) of the genome covering 135.1 mb even by more stringent criteria (P<0.001 and SD>or=0.25), reflecting ethnic diversity of structural variations between Korean and other populations. Some CNVRs were validated by the quantitative multiplex PCR of short fluorescent fragment (QMPSF) method, and then copy number invariant regions were detected among the study subjects. These copy number invariant regions would be used as good internal controls for further CNV studies. Lastly, we demonstrated that the CNV information could stratify even a single ethnic population with a proper reference genome assembly from multiple heterogeneous populations.

Catalposide, a compound isolated from catalpa ovata, attenuates induction of intestinal epithelial proinflammatory gene expression and reduces the severity of trinitrobenzene sulfonic Acid-induced colitis in mice.

Certain irinoid-producing plants have been used as herbal anti-inflammatory remedies. Here we evaluated whether catalposide (CATP), a single compound isolated from irinoid-producing plant Catalpa ovata, has a potential for preventing or ameliorating diseases characterized by mucosal inflammation. Preliminary microarray-based gene expression test revealed that CATP, which alone did not significantly affect expression of any of the >8,000 genes analyzed, attenuated the expression of tumor necrosis factor-alpha (TNF-alpha)-induced proinflammatory genes including interleukin-8 (IL-8) in human intestinal epithelial HT-29 cells. Down-regulation of IL-8 mRNA accumulation was also reflected by the decreased IL-8 secretion in CATP-treated HT-29 cells. The signal transduction study revealed that CATP significantly attenuates TNF-alpha-mediated p38 and extracellular signal-regulated kinase (ERK) phosphorylation. Further, CATP reduced NF-kappaB-mediated transcriptional activation as well as Ikappa-Balpha degradation. To establish the in vivo relevance of these findings, we examined whether CATP could affect intestinal inflammation in vivo using the mouse model of trinitrobenzene sulfonic acid (TNBS)-induced inflammatory colitis. Intrarectal administration of CATP dramatically reduced the weight loss, colonic damage, and mucosal ulceration that characterize TNBS colitis. Moreover, CATP suppressed the expression of TNF-alpha, interleukin-1beta, and intercellular adhesion molecule-1 along with the inhibition of NF-kappa B p65 translocation into nucleus in TNBS colitis. Collectively, current results demonstrate that CATP may be an effective agent for the treatment of diseases characterized by mucosal inflammation.

Iron chelator triggers inflammatory signals in human intestinal epithelial cells: involvement of p38 and extracellular signal-regulated kinase signaling pathways.

Competition for cellular iron (Fe) is a vital component of the interaction between host and pathogen. Most bacteria have an obligate requirement for Fe to sustain infection, growth, and survival in host. To obtain iron required for growth, many bacteria secrete iron chelators (siderophores). This study was undertaken to test whether a bacterial siderophore, deferoxamine (DFO), could trigger inflammatory signals in human intestinal epithelial cells as a single stimulus. Incubation of human intestinal epithelial HT-29 cells with DFO increased the expression of IL-8 mRNA, as well as the release of IL-8 protein. The signal transduction study revealed that both p38 and extracellular signal-regulated kinase-1/2 were significantly activated in response to DFO. Accordingly, the selective inhibitors for both kinases, either alone or in combination, completely abolished DFO-induced IL-8 secretion, indicating an importance of mitogen-activated protein kinases pathway. These proinflammatory effects of DFO were, in large part, mediated by activation of Na(+)/H(+) exchangers, because selective blockade of Na(+)/H(+) exchangers prevented the DFO-induced IL-8 production. Interestingly, however, DFO neither induced NF-kappaB activation by itself nor affected IL-1beta- or TNF-alpha-mediated NF-kappaB activation, suggesting a NF-kappaB-independent mechanism in DFO-induced IL-8 production. Global gene expression profiling revealed that DFO significantly up-regulates inflammation-related genes including proinflammatory genes, and that many of those genes are down-modulated by the selective mitogen-activated protein kinase inhibitors. Collectively, these results demonstrate that, in addition to bacterial products or cell wall components, direct chelation of host Fe by infected bacteria may also contribute to the evocation of host inflammatory responses.