Serum Lipopolysaccharide-Binding Protein Concentrations in Trauma Victims

Background: In low concentrations, lipopolysaccharide-binding protein (LBP), an acute-phase protein recognizing lipopolysaccharide (LPS), catalyzes its transfer to the cellular receptor consisting of CD14 and Toll-like receptor-4. Previous studies have documented increased serum LBP concentrations in patients with sepsis, systemic inflammatory response syndrome (SIRS), or acute pancreatitis and after cardiopulmonary bypass. No prior studies have examined LBP expression in trauma victims. We hypothesized that admission LBP plasma concentrations are predictive of outcome (mortality) in trauma. This study assessed time-dependent changes in serum LBP concentrations in trauma patients soon after injury. Methods: A prospective, single-institution, observational cohort study of 121 adult trauma patients (age ≥17 years) with moderate to severe injury who required hospitalization. The trauma patients were male in 79.6% of the cases and had a mean age of 43.0 ± 20.6 years. The mean injury severity score (ISS) was 23 ± 12, and the crystalloid resuscitation volume given in the first 24 h averaged 6,640 ± 3,729 mL. Informed consent was obtained on admission, and blood samples were drawn on admission and at 24 h postadmission. Prospective data were collected for daily SIRS score, multiple organ dysfunction score (MODS), and sequential organ failure assessment (SOFA) score, complications, and outcomes. Plasma concentrations of LBP were measured by enzyme-linked immunosorbent assay. Results: Sixty patients (48.8% of the study cohort) required emergency surgical intervention and sustained a substantial intraoperative blood loss (mean 1,404 ± 2,757 mL). The hospital mortality rate was 16.3% (20 patients). The mean intensive care unit stay was 8.9 ± 16.4 days, and the hospital stay was 14.8 ± 19.6 days. The patients had a significantly higher serum concentrations of LBP on admission (mean 28.0 ± 25.3 mg/L; range 2–100 mg/L) than did control subjects (mean 6.2 ± 2.1 mg/L; range 1.3–12.8 mg/L; p < 0.01), similar to the plasma concentrations previously reported in septic patients. A significant increase in LBP concentration was noted at 24 h (mean 72.3 ± 45.7 mg/L; range 8–210 mg/L; p < 0.05). The admission LBP concentration was significantly greater in nonsurvivors than in survivors. However, after controlling for age and ISS, the admission LBP concentration did not predict death.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63423/1/sur.2006.7.251.pd

Polyamine depletion induces nucleophosmin modulating stability and transcriptional activity of p53 in intestinal epithelial cells

Our previous studies have shown that polyamines are required for normal intestinal mucosal growth and that decreased levels of polyamines inhibit intestinal epithelial cell (IEC) proliferation by stabilizing p53 and other growth-inhibiting proteins. Nucleophosmin (NPM) is a multifunctional protein that recently has been shown to regulate p53 activity. In the present study, we sought to determine whether polyamine depletion increases NPM modulating, the stability and transcriptional activity of p53 in a normal IEC-6 intestinal epithelial cell line. Depletion of cellular polyamines by α- difluoromethylornithine, the specific inhibitor of polyamine biosynthesis, stimulated expression of the NPM gene and induced nuclear translocation of NPM protein. Polyamine depletion stimulated NPM expression primarily by increasing NPM gene transcription and its mRNA stability, and it induced NPM nuclear translocation through activation of phosphorylation of mitogen-activated protein kinase kinase. Increased NPM interacted with p53 and formed a NPM/p53 complex in polyamine-deficient cells. Inhibition of NPM expression by small interfering RNA targeting NPM (siNPM) not only destabilized p53 as indicated by a decrease in its protein half-life but also prevented the increased p53-dependent transactivation as shown by suppression of the p21 promoter activity. Decreased expression of NPM by siNPM also promoted cell growth in polyamine-deficient cells. These results indicate that 1) polyamine depletion increases expression of the NPM gene and enhances NPM nuclear translocation and 2) increased NPM interacts with and stabilizes p53, leading to inhibition of IEC-6 cell proliferation

Cation flux through SUR1-TRPM4 and NCX1 in astrocyte endfeet induces water influx through AQP4 and brain swelling after ischemic stroke

Brain swelling causes morbidity and mortality in various brain injuries and diseases but lacks effective treatments. Brain swelling is linked to the influx of water into perivascular astrocytes through channels called aquaporins. Water accumulation in astrocytes increases their volume, which contributes to brain swelling. Using a mouse model of severe ischemic stroke, we identified a potentially targetable mechanism that promoted the cell surface localization of aquaporin 4 (AQP4) in perivascular astrocytic endfeet, which completely ensheathe the brain\u27s capillaries. Cerebral ischemia increased the abundance of the heteromeric cation channel SUR1-TRPM4 and of the Na/Ca exchanger NCX1 in the endfeet of perivascular astrocytes. The influx of Na through SUR1-TRPM4 induced Ca transport into cells through NCX1 operating in reverse mode, thus raising the intra-endfoot concentration of Ca. This increase in Ca stimulated calmodulin-dependent translocation of AQP4 to the plasma membrane and water influx, which led to cellular edema and brain swelling. Pharmacological inhibition or astrocyte-specific deletion of SUR1-TRPM4 or NCX1 reduced brain swelling and improved neurological function in mice to a similar extent as an AQP4 inhibitor and was independent of infarct size. Thus, channels in astrocyte endfeet could be targeted to reduce postischemic brain swelling in stroke patients