Activation of complement factor B contributes to murine and human myocardial ischemia/reperfusion injury.

The pathophysiology of myocardial injury that results from cardiac ischemia and reperfusion (I/R) is incompletely understood. Experimental evidence from murine models indicates that innate immune mechanisms including complement activation via the classical and lectin pathways are crucial. Whether factor B (fB), a component of the alternative complement pathway required for amplification of complement cascade activation, participates in the pathophysiology of myocardial I/R injury has not been addressed. We induced regional myocardial I/R injury by transient coronary ligation in WT C57BL/6 mice, a manipulation that resulted in marked myocardial necrosis associated with activation of fB protein and myocardial deposition of C3 activation products. In contrast, in fB-/- mice, the same procedure resulted in significantly reduced myocardial necrosis (% ventricular tissue necrotic; fB-/- mice, 20 ± 4%; WT mice, 45 ± 3%; P < 0.05) and diminished deposition of C3 activation products in the myocardial tissue (fB-/- mice, 0 ± 0%; WT mice, 31 ± 6%; P<0.05). Reconstitution of fB-/- mice with WT serum followed by cardiac I/R restored the myocardial necrosis and activated C3 deposition in the myocardium. In translational human studies we measured levels of activated fB (Bb) in intracoronary blood samples obtained during cardio-pulmonary bypass surgery before and after aortic cross clamping (AXCL), during which global heart ischemia was induced. Intracoronary Bb increased immediately after AXCL, and the levels were directly correlated with peripheral blood levels of cardiac troponin I, an established biomarker of myocardial necrosis (Spearman coefficient = 0.465, P < 0.01). Taken together, our results support the conclusion that circulating fB is a crucial pathophysiological amplifier of I/R-induced, complement-dependent myocardial necrosis and identify fB as a potential therapeutic target for prevention of human myocardial I/R injury.

Activated Complement Factors as Disease Markers for Sepsis.

Sepsis is a leading cause of death in the United States and worldwide. Early recognition and effective management are essential for improved outcome. However, early recognition is impeded by lack of clinically utilized biomarkers. Complement factors play important roles in the mechanisms leading to sepsis and can potentially serve as early markers of sepsis and of sepsis severity and outcome. This review provides a synopsis of recent animal and clinical studies of the role of complement factors in sepsis development, together with their potential as disease markers. In addition, new results from our laboratory are presented regarding the involvement of the complement factor, mannose-binding lectin, in septic shock patients. Future clinical studies are needed to obtain the complete profiles of complement factors/their activated products during the course of sepsis development. We anticipate that the results of these studies will lead to a multipanel set of sepsis biomarkers which, along with currently used laboratory tests, will facilitate earlier diagnosis, timely treatment, and improved outcome.

Loss of plasma membrane integrity, complement response and formation of reactive oxygen species during early myocardial ischemia/reperfusion.

Loss of plasma membrane integrity (LPMI) is a hallmark of necrotic cell death. The involvement of complement and ROS in the development of LPMI during the early stages of murine myocardial ischemia-reperfusion injury was investigated. LPMI developed within 1 h of reperfusion to a level that was sustained through 24 h. C3 deposition became significant at 3-h reperfusion and thus contributed little to LPMI prior to this time. SOD1 transgenic mice had significantly less LPMI compared with WT mice at 1 h of reperfusion but not at later time points. Catalase transgenic mice were not protected from LPMI at 1-h reperfusion compared with WT mice, but had 69% less LPMI at 3-h reperfusion. This protection was transient. At 24-h reperfusion the LPMI of catalase transgenic mice was identical to that of WT mice. The delayed benefits of over-expressed catalase compared with SOD1 are consistent with its antioxidant action downstream of SOD1. The onset of LPMI occurs within 1 h of reperfusion at a level that is maintained through 24 h. ROS contribute significantly to LPMI during the first 3 h of reperfusion, while complement deposition, which becomes significant after 3-h reperfusion, may contribute thereafter.

Patients with detectable cocaethylene are more likely to require intensive care unit admission after trauma.

Cocaethylene (CE) is a toxic metabolite that is formed after simultaneous consumption of cocaine and ethanol. This potent stimulant is more toxic than cocaine and has a longer half-life. The deleterious hemodynamic and cardiovascular effects of CE have been proven in animal models. The aim of this study is to assess the impact of CE on clinical outcomes after trauma. We prospectively enrolled adult (≥13 years) trauma patients requiring admission. Predictor variables were age, sex, mechanism of injury, Injury Severity Score, base deficit, and toxicology groups (ethanol alone, cocaine alone, CE, and none). The outcomes examined were mortality, intensive care unit (ICU) admission, and length of hospital stay (LOS). We used nonparametric tests to compare continuous variables and χ² test to compare categorical data. We constructed a logistic regression to identify variables that could predict mortality and ICU admission. We enrolled 417 patients (74% male; 70% blunt injury; median age, 40 [range, 13-95]; overall mortality, 2.2%). Urine toxicology and serum ethanol level screens classified patients into the following groups: 13.4% ethanol only, 4.1% cocaine only, 8.9% CE, and 46% none. Mortality and LOS were not statistically different among the groups. In logistic regression analysis, none of the variables were statistically significant in predicting mortality. However, the presence of CE significantly increased the likelihood of ICU admission (odds ratio, 5.9; 95% confidence interval, 1.6-22). The presence of detectable CE in the urine does not increase the mortality or LOS in trauma patients requiring admission but does increase the likelihood of ICU admission.

Cpc2/RACK1 is a ribosome-associated protein that promotes efficient translation in Schizosaccharomyces pombe.

Cpc2/RACK1 is a highly conserved WD domain protein found in all eucaryotes. Cpc2/RACK1 functions on mammalian signal transduction pathways most notably as an adaptor protein for the betaII protein kinase C isozyme. In single cell eucaryotes, Cpc2/RACK1 regulates growth, differentiation, and entry into G0 stationary phase. The exact biochemical function of Cpc2/RACK1 is unknown. Here, we provide evidence that Cpc2 is associated with the ribosome. Using immunoaffinity purification, we isolated ribosomal proteins in association with Cpc2/RACK1. Polysome and ribosomal subunit analysis using velocity gradient centrifugation of cell lysates demonstrated that Cpc2 co-sediments with the 40 S ribosomal subunit and with polysomes. Conditions known to disrupt ribosome structure alter sedimentation of the ribosome and of Cpc2/RACK1 coordinately. Loss of cpc2 does not dramatically alter the rate of cellular protein synthesis but causes a decrease in the steady state level of numerous proteins, some of which regulate methionine metabolism. Whereas real time PCR analysis demonstrated that transcriptional mechanisms are responsible for down-regulation of some of these proteins, one protein, ribosomal protein L25, is probably regulated at the level of translation.

Hidden errors of aneroid sphygmomanometers.

BACKGROUND: Measurement of blood pressure remains the most commonly performed screening test in medical practice. With the likely removal of mercury sphygmomanometers from the workplace alternative devices are required. Of these the aneroid sphygmomanometer is popular both in the community and hospital setting. We investigated the accuracy of all the aneroid and mercury sphygmomanometers during dynamic calibration within a tertiary referral maternity hospital. METHODS: We compared the accuracy of 39 aneroid and 36 mercury sphygmomanometers to a recently calibrated and serviced mercury sphygmomanometer (the accepted gold standard). All devices were in current clinical use. Using three blinded, trained observers, 30 different pressures were checked throughout the pressure range following British Hypertension Society protocol guidelines. RESULTS: Only 31 (86%) of the mercury devices and 36 (92%) of the aneroid devices were in adequate working condition and suitable for analysis. Significantly more aneroid devices had systematic errors of > 5 mmHg (19 versus 3%, < 0.05). Fifty percent of aneroid devices had at least one reading > 10 mmHg out compared to only 10% of mercury devices (chi square programme). CONCLUSIONS: Aneroid sphygmomanometers in apparent good working order are inaccurate compared to mercury devices. Some of these faults can only be detected during dynamic testing. To minimize the risk of erroneous blood pressure recording, aneroid devices should be regularly checked for accuracy using dynamic calibration methods as recommended in validation protocols.