Shock : molecular, cellular, and systemic pathobiological aspects and therapeutic approaches : the official journal the Shock Society, the European Shock Society, the Brazilian Shock Society, the International Federation of Shock Societies
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High-mobility group box 1 (HMGB1) is a nuclear factor and a secreted protein. During inflammation, HMGB1 is secreted into the extracellular space where it can interact with the receptor for advanced glycation end products and trigger proinflammatory signals. Extracellular HMGB1 plays a critical role in several inflammatory diseases such as sepsis and rheumatoid arthritis. ⋯ The MEK1/2 inhibitor PD98059 also suppressed HMGB1 release and activation of nuclear factor κB induced by VPA. Valproic acid induced expression of γ-aminobutyric acid receptors in macrophages, and picrotoxin, a γ-aminobutyric acid A receptor antagonist, inhibited the VPA-activated phosphorylation of ERK and VPA-induced HMGB1 release. These results suggest that VPA may exacerbate innate immune responses to endotoxin through enhanced release of HMGB1.
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Hemorrhagic-traumatic shock (HTS) followed by reperfusion induces heme oxygenase (HO) 1. Free iron (Fe2+) may cause oxidative stress, if not adequately sequestered. We aimed to characterize HO-1-mediated effects on Fe2+ levels in liver and transferrin-bound iron (TFBI) in plasma following HTS, including laparotomy, bleeding, and inadequate and adequate reperfusion. ⋯ All animals undergoing HTS displayed increased TFBI levels after reperfusion; however, in animals pretreated with hemin, TFBI levels increased less. Our data indicate that increase in Fe2+ levels in liver and plasma early after HTS is not mediated by HO-1 upregulation, but possibly reflects an increased mobilization from internal iron stores or increased cell damage. Thus, upregulation of HO activity by hemin does not increase Fe2+ levels following HTS and reperfusion.
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Translocation of bacteria and other luminal factors from the intestine following surgical injury can be a major driver of critical illness. Bile acids have been shown to play a key role in the loss of intestinal epithelial barrier function during states of host stress. Experiments to study the ability of nonionic block copolymers to abrogate barrier failure in response to bile acid exposure are described. ⋯ Preliminary transepithelial electrical resistance-based studies examining structure-function correlates of polymer protection against bile acid damage were performed with a small library of PEG-based copolymers. Polymer properties associated with optimal protection against bile acid-induced barrier disruption were PEG-based compounds with a molecular weight greater than 10 kd and amphiphilicity. The data demonstrate that PEG-based copolymer architecture is an important determinant that confers protection against bile acid injury of intestinal epithelia.
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Sepsis is a poorly understood syndrome. Therefore, we examined the mechanisms underlying failed regeneration in sham-operated (SO), mildly septic (cecal ligation and single puncture [CLP]), and severely septic (cecal ligation with two punctures [2CLP]) C57Bl6 mice. Relative to no operation (T0) or SO, CLP, but not 2CLP, increased the number of cells staining for proliferating cell nuclear antigen, a marker for cell division. ⋯ Finally, CLP increased the steady-state abundance of the mRNAs encoding thymidine kinase, DNA polymerase α, and dihydrofolate reductase, all required for DNA replication. No changes were noted after 2CLP. We conclude that 2CLP impaired hepatocyte proliferation following 2CLP in part via impaired cyclin D1/cdk-4-induced phosphorylation of pRb, maintaining the association between pRb and E2F and inhibited E2F transcriptional activity.