Hemodynamic and Cardiac Contractile Function During Sepsis Caused by Cecal Ligation and Puncture in Mice

EFFECT OF SESAME OIL ON OXIDATIVE-STRESS-ASSOCIATED RENAL INJURY IN ENDOTOXEMIC RATS: INVOLVEMENT OF NITRIC OXIDE AND PROINFLAMMATORY CYTOKINES

This study aimed to investigate the effect of sesame oil on oxidative stress-associated renal injury induced by lipopolysaccharide in rats. The effects of sesame oil on renal injury, oxidative stress, hydroxyl radical, superoxide anion, nitric oxide, and proinflammatory cytokines were assessed after a lipopolysaccharide challenge. Sesame oil attenuated lipopolysaccharide-induced renal injury, decreased lipid peroxidation, increased the activities of superoxide dismutase, catalase, and glutathione peroxidase, reduced hydroxyl radical generation and nitric oxide production, and had no effect on superoxide anion generation in lipopolysaccharide-challenged rats. In addition, sesame oil significantly decreased tumor necrosis factor-alpha and interleukin 1beta production 1 and 6 h, respectively, after lipopolysaccharide administration in mice. Thus, sesame oil attenuates oxidative stress-associated renal injury via reduction of the production of nitric oxide and the generation of proinflammatory cytokines in endotoxemic rats.

Targeted complement inhibition by C3d recognition ameliorates tissue injury without apparent increase in susceptibility to infection

Previous studies indicate a pivotal role for complement in mediating both local and remote injury following ischemia and reperfusion of the intestine. Here, we report on the use of a mouse model of intestinal ischemia/reperfusion injury to investigate the strategy of targeting complement inhibition to sites of complement activation by linking an iC3b/C3dg-binding fragment of mouse complement receptor 2 (CR2) to a mouse complement-inhibitory protein, Crry. We show that the novel CR2-Crry fusion protein targets sites of local and remote (lung) complement activation following intestinal ischemia and reperfusion injury and that CR2-Crry requires a 10-fold lower dose than its systemic counterpart, Crry-Ig, to provide equivalent protection from both local and remote injury. CR2-Crry has a significantly shorter serum half-life than Crry-Ig and, unlike Crry-Ig, had no significant effect on serum complement activity at minimum effective therapeutic doses. Furthermore, the minimum effective dose of Crry-Ig significantly enhanced susceptibility to infection in a mouse model of acute septic peritonitis, whereas the effect of CR2-Crry on susceptibility to infection was indistinguishable from that of PBS control. Thus, compared with systemic inhibition, CR2-mediated targeting of a complement inhibitor of activation improved bioavailability, significantly enhanced efficacy, and maintained host resistance to infection.

Direct comparison of magnetic resonance imaging and conductance microcatheter in the evaluation of left ventricular function in mice

The aim of the present work was to study the reliability of conductance microcatheter volumetric measurements as compared to magnetic resonance imaging (MRI) in the same set of mice. Mice left ventricular (LV) volumes were monitored under basal conditions and in a hypertrophy model induced by transverse aortic constriction (TAC). Cardiac function was evaluated in isoflurane anesthetized mice (n = 8) by MRI followed by 1.4 F Millar microtip catheter measurements. The second group of mice with TAC-induced cardiac hypertrophy was studied eight weeks after surgery. Reliability of 3D-reconstructed MRI data was confirmed by comparison with autopsy masses (autopsy LV mass = 73.6 +/- 3.4 mg; MRI LV mass = 76.9 +/- 3.7 mg). Conduction catheter was found to greatly underestimate end-diastolic and end-systolic volumes and thus stroke volume as well as cardiac output in control mice (MRI: EDV = 79 +/- 8 microl, ESV = 27+/-9 microl, SV = 51 +/- 9 microl, CO = 25 +/- 6 ml/min; Catheter: EDV = 28 +/- 5 microl, ESV = 8 +/- 4 microl, SV = 19 +/- 4 microl, CO = 10 +/- 2 ml/min). However, values for ejection fraction showed no significant differences between the two methods. In the hypertrophy model, stroke volume and cardiac output were increased when measured with MRI (SV: +19 +/- 20%; CO: +28 +/- 27%), whereas catheter data showed opposite directional changes (SV: -22 +/- 37%; CO: -31 +/- 37%). Ejection fraction was found to be reduced only in catheter measurements (-31 +/- 26%). In summary, our data demonstrate that absolute volumetric values are strikingly underestimated by conduction catheter measurements and that even detection of directional changes with this method may not always be feasible.

Cardiovascular dysfunction caused by cecal ligation and puncture is attenuated in CD8 knockout mice treated with anti-asialoGM1

The present study was designed to assess hemodynamics and myocardial function at 18 h after injury caused by cecal ligation and puncture (CLP) in CD8-knockout mice treated with anti-asialoGM1 (CD8KO/alphaAsGM1 mice). Arterial pressure was measured by carotid artery cannulation, and left ventricular pressure-volume measurements were obtained by use of a 1.4-Fr conductance catheter. Blood acid-base balance and indexes of hepatic, renal, and pulmonary injury were also measured. CD8KO/alphaAsGM1 mice exhibited higher mean arterial pressure and increased systemic vascular resistance compared with wild-type mice. Cardiac output was significantly decreased in wild-type, but not CD8KO/alphaAsGM1, mice compared with sham controls. Myocardial function was better preserved in CD8KO/alphaAsGM1 mice as indicated by less impairment of left ventricular pressure development over time, time varying maximum elastance, end-systolic pressure-volume relationship, and preload recruitable stroke work. The impairment in myocardial function was associated with induction of proinflammatory cytokine mRNAs in the hearts of wild-type mice. The hemodynamic derangements in wild-type mice were coupled with significant metabolic acidosis and elevated serum creatinine levels. Overall, this study shows that cardiovascular collapse and shock characterized by hypotension, myocardial depression, low systemic vascular resistance, and metabolic acidosis occurs after CLP in wild-type mice but is attenuated in CD8KO/alphaAsGM1 mice. These observations likely explain, in part, the previously observed survival advantage of CD8KO/alphaAsGM1 mice following CLP.

Cecal ligation and puncture versus colon ascendens stent peritonitis: two distinct animal models for polymicrobial sepsis

Colon ascendens stent peritonitis (CASP) and cecal ligation and puncture (CLP), two animal models designed to closely mimic the clinical course of intra-abdominal sepsis, were compared. In the past, immunomodulatory therapies developed in animal studies failed to be successful in humans. As a consequence, the established animal sepsis models were criticized. It has been proposed that present models had to be reevaluated, and new, clinically more relevant models should be evolved. CLP procedure was performed puncturing once (CLP[1]) or twice (CLP[2]) the ligated cecum of C57BL/6 mice. In the CASP model, a stent with defined diameter was surgically inserted into the ascending colon. Survival, bacterial load, immunohistochemistry, and serum cytokine levels were analyzed in the groups. Survival after CASP procedure correlated strongly with the stent diameter, whereas the number of punctures in CLP did not significantly change survival rate. Bacterial loads of peritoneal lavage, liver, and lung, as well as serum cytokine levels (tumor necrosis factor, interleukin 1 beta, interleukin 10) steadily increased from 6 to 24 h after the CASP procedure. In contrast, continuously low amounts of bacteria and cytokines were found in CLP mice at any point of time. Twenty-four hours after CLP surgery, the ligated cecum was covered by adhesive small bowel loops, whereas in CASP mice, the intestinal leakage was then still present. The CASP model mimics closely the clinical course of diffuse peritonitis with early and steadily increasing systemic infection and inflammation (systemic inflammatory response syndrome). In contrast, CLP reveals a model of intra-abdominal abscess formation with sustained and minor signs of systemic inflammation.

Beta2-microglobulin knockout mice treated with anti-asialoGM1 exhibit improved hemodynamics and cardiac contractile function during acute intra-abdominal sepsis

We previously showed that beta2-microglobulin knockout mice treated with anti-asialoGM1 (beta2M/alphaAsGM1 mice) exhibit less hypothermia, reduced production of proinflammatory cytokines, less metabolic acidosis, and improved survival after cecal ligation and puncture (CLP) compared with wild-type mice. The present study was designed to assess hemodynamics and left ventricular contractility at 18 h after CLP. Arterial pressure was measured by carotid artery cannulation, and left ventricular pressure-volume loops were obtained by insertion of a 1.4-F conductance catheter into the left ventricle. Heart rate, stroke volume, and cardiac output were not significantly different between wild-type and beta2M/alphaAsGM1 mice after CLP. However, beta2M/alphaAsGM1 mice exhibited improved mean arterial pressure and systemic vascular resistance compared with wild-type mice. Myocardial function was also better preserved in beta2M/alphaAsGM1 mice as indicated by improved left ventricular pressure development over time, time-varying maximum elastance, endsystolic pressure-volume relationship, and preload recruitable stroke work. Overall, this study shows that cardiovascular collapse characterized by hypotension, myocardial depression, and low systemic vascular resistance occurs after CLP in wild-type mice. However, beta2M/alphaAsGM1 mice exhibit improved hemodynamics and cardiac contractile function after CLP that may account, in part, for our previously observed survival benefit.