Lidocaine attenuates sepsis-induced diaphragmatic dysfunction in hamsters

OBJECTIVES: Sepsis or endotoxemia causes diaphragmatic dysfunction, which may contribute to respiratory distress. Toxic free radicals are partly responsible for the pathogenesis. Lidocaine scavenges the reactive molecules. The purpose of the current study was to examine whether lidocaine prevents the diaphragmatic dysfunction of sepsis. DESIGN: Prospective, randomized animal study. SETTING: University research laboratory. SUBJECTS: A total of 40 male Golden-Syrian hamsters. INTERVENTIONS: The animals were randomly allocated to one of five groups (n = 8 each): hamsters undergoing sham laparotomy alone and receiving saline infusion (Sham group), those undergoing cecal ligation with puncture (CLP) and receiving an infusion of saline (Sepsis group), those undergoing sham laparotomy and receiving infusion of lidocaine, 2 mg/kg/hr (Sham-LID group), those undergoing CLP and receiving infusion of lidocaine, 1 mg/kg/hr (Sepsis-LID 1 group), and those undergoing CLP and receiving infusion of lidocaine, 2 mg/kg/hr (Sepsis-LID 2 group). Subcutaneous infusion of saline or lidocaine was started 6 hrs before surgery and continued until 24 hrs after the operation when all hamsters were killed. MEASUREMENTS AND MAIN RESULTS: Diaphragmatic contractility and fatigability were assessed in vitro by using muscle strips excised from the costal diaphragms. Diaphragmatic levels of malondialdehyde (MDA), an index of free radicals-mediated lipid peroxidation, were also measured. Twitch and tetanic tensions in the Sepsis group were reduced compared with the Sham group. Tensions generated during fatigue trials were decreased, and MDA levels were elevated in diaphragms from the Sepsis group. An infusion of 2 mg/kg/hr lidocaine attenuated contractile dysfunction, aggravation of fatigability, and the increase in MDA formation. In contrast, 1 mg/kg/hr lidocaine failed to do so. Electrophysiologic diaphragmatic characteristics in the Sham-LID group were similar to those in the Sham group. CONCLUSIONS: Pretreatment with 2 mg/kg/hr but not 1 mg/kg/hr lidocaine attenuated sepsis-induced diaphragmatic dysfunction in hamsters assessed by contractile profiles and endurance capacity. This beneficial effect of lidocaine may be attributable, in part, to inhibition of lipid peroxidation in the diaphragm.     

Treatment with N-acetylcysteine plus deferoxamine protects rats against oxidative stress and improves survival in sepsis

OBJECTIVE: Oxidative stress plays an important role in the development of multiple organ failure and septic shock. Here we have evaluated the effects of a combination of antioxidants (N-acetylcysteine plus deferoxamine) in a murine model of polymicrobial sepsis induced by cecal ligation and puncture (CLP). DESIGN: Prospective, randomized, controlled experiment. SETTING: Animal basic science laboratory. SUBJECTS: Male Wistar rats, weighing 300-350 g. INTERVENTIONS: Rats subjected to CLP were treated with either N-acetylcysteine (20 mg/kg, 3 hrs, 6 hrs, 12 hrs, 18 hrs, and 24 hrs after CLP, subcutaneously) plus deferoxamine (20 mg/kg, 3 hrs and 24 hrs after CLP, subcutaneously) or vehicle with or without "basic support" (saline at 50 mL/kg immediately and 12 hrs after CLP plus ceftriaxone at 30 mg/kg and clindamycin 25 mg/kg every 6 hrs). MEASUREMENTS AND MAIN RESULTS: After 12 hrs, tissue myeloperoxidase (indicator of neutrophil infiltration), thiobarbituric acid reactive species (as a marker of oxidative stress), catalase and superoxide dismutase activities (antioxidant enzymes), and mitochondrial superoxide production (index of uncoupling of electron transfer chain) were measured in major organs involved in septic response. Rats treated with antioxidants had significantly lower myeloperoxidase activity and thiobarbituric acid reactive species formation in all organs studied. Mitochondrial superoxide production was significantly reduced by antioxidant treatment. Furthermore, antioxidants significantly improved the balance between catalase and superoxide dismutase activities. Survival in untreated septic rats was 10%. Survival increased to 40% with fluids and antibiotics. In rats treated only with N-acetylcysteine plus deferoxamine, survival was also significantly improved (47%) in a manner similar to basic support. Survival increased to 66% with basic support with N-acetylcysteine plus deferoxamine. CONCLUSIONS: Our data provide the first experimental demonstration that N-acetylcysteine plus deferoxamine reduces the consequences of septic shock induced by CLP in the rat, by decreasing oxidative stress and limiting neutrophil infiltration and mitochondrial dysfunction, thereby improving survival.     

Geranylgeranylacetone attenuates septic diaphragm dysfunction by induction of heat shock protein 70

OBJECTIVE: The purposes of the present study were to evaluate the induction of heat shock protein (HSP) 70 expression in the diaphragm by geranylgeranylacetone (GGA) administration and to determine the effect of HSP70 induction on diaphragm contractility measured in vitro and the production of oxygen-derived free radicals during experimental septic peritonitis. DESIGN: Prospective laboratory study. SETTING: University laboratory. SUBJECTS: One-hundred sixty male Wistar rats. INTERVENTIONS: In experiment 1, rats received GGA intragastrically, and time-dependent induction of HSP70 expression in the diaphragm was determined at 0, 12, 24, and 36 hrs after GGA administration. To evaluate dose-dependent inhibition of GGA-induced HSP70 expression by quercetin, rats were pretreated with progressive doses of quercetin before GGA administration. In experiment 2, rats received gum arabic solution (vehicle), 100, 200, or 400 mg/kg of GGA. In experiment 3, rats were pretreated with quercetin or glycerol before GGA or vehicle administration. Intra-abdominal sepsis was induced by cecal ligation and perforation (CLP) under inhalation anesthesia after GGA or vehicle administration in experiments 2 and 3. MEASUREMENTS AND MAIN RESULTS: Western blot analysis using diaphragm homogenates obtained from normal rats showed that HSP70 expression peaked at 24 or 36 hrs after GGA administration and that pretreatment with >10 mg/kg of quercetin blocked the induction of HSP70 expression by GGA. CLP induced diaphragmatic dysfunction and increased diaphragmatic malondialdehyde concentrations and superoxide dismutase and glutathione peroxidase activities. GGA attenuated CLP-induced diaphragm dysfunction and increased malondialdehyde concentrations in a dose-dependent manner but did not affect superoxide dismutase and glutathione peroxidase activities after CLP. Diaphragm dysfunction and increased diaphragmatic malondialdehyde concentrations after CLP were maintained on quercetin pretreatment despite GGA administration. CONCLUSIONS: GGA induces HSP70 expression in the diaphragm, and this induction attenuates septic diaphragm impairment by inhibiting the production of oxygen-derived free radicals.     

Transdermal treatment with tulobuterol increases isometric contractile properties of diaphragm muscle in mice

Clinically, patients suffering from bronchial asthma are often treated transdermally with tulobuterol patches to dilate the bronchi. Tulobuterol, a synthetic beta(2) agonist, is also thought to act as a diaphragm muscle contractor, like other beta(2) sympathomimetic drugs. However, it has not been clarified that transdermal treatment with tulobuterol influences diaphragm muscle contractility. We therefore examined its effects on contractile properties of such muscles obtained from BALB/c mice. Two systems, a tulobuterol incubation group (in vitro) and a tulobuterol transdermal treatment group (in vivo), were employed. In both groups, the contractile properties of the dissected diaphragm muscles were measured by field stimulation in an organ bath. In the incubation group, the diaphragm muscle of untreated mice was incubated in an organ buffer at 10(-7), 10(-6), or 10(-5) M tulobuterol for 1 hr and then measured for contractility. Tulobuterol significantly increased force-frequency curves at a concentration of 10(-5) M at 1 (p < 0.01), 30, 50, 70, 100, and 120 Hz (p < 0.05, each) compared with the values at 0 M. In the transdermal treatment group, the diaphragm muscle was dissected from animals at 1, 4, 8, 12, or 24 hrs after treatment and measured for contractility, showing that the force-frequency curves were significantly increased and maintained from 4 to 24 hrs (each p < 0.01 as compared with the sham-treated group). We suggest that transdermal tulobuterol treatment in case of bronchial asthma is useful not only for bronchial dilatation, but also for increasing diaphragm muscle contractility.     

Time course of nitric oxide,peroxynitrite, and antioxidants in the endotoxemic heart

OBJECTIVES: To determine the time course for myocardial production of nitric oxide, peroxynitrite, and glutathione, to determine the activities of the myocardial antioxidant enzymes glutathione peroxidase, superoxide dismutase, and glutathione reductase throughout endotoxemia and into recovery, and to correlate the levels of these variables to left ventricular contractility in endotoxemia. DESIGN: Rats were treated with lipopolysaccharide. Endotoxemic hearts were examined at baseline, 4, 16, 24, and 48 hrs after lipopolysaccharide. Saline time-control groups were treated identically. SETTING: A pulmonary research laboratory of a university teaching hospital. MEASUREMENTS AND MAIN RESULTS: Lipopolysaccharide administration resulted in decreased contractility at 16 hrs as assessed by the isolated papillary muscle technique. Contractility recovered by 24 hrs. Myocardial glutathione content initially increased, but it was decreased from baseline by 16 hrs, as was glutathione peroxidase activity. Both superoxide dismutase and glutathione reductase activities were increased early (4 hrs) and remained elevated throughout the course of the experiment. Myocardial nitric oxide content (assessed by the chemiluminescence technique) was increased by 4 hrs and was markedly elevated by 16 hrs. Nitric oxide levels remained elevated despite recovery of contractility at 24 hrs. Similarly, peroxynitrite (assessed by measurement of 3-nitrotyrosine by high-pressure liquid chromatography) was elevated at 16 hrs and remained elevated despite normalization of contractility at 24 and 48 hrs. CONCLUSIONS: Myocardial dysfunction in endotoxemia correlates mainly with decreased glutathione content and glutathione peroxidase activity rather than nitric oxide or peroxynitrite formation. These data indicate that lipopolysaccharide-induced myocardial dysfunction is not solely caused by elevated myocardial nitric oxide levels but rather caused by the sum of complex interactions between various oxygen- and nitrogen-derived radicals.     

Is prostacyclin responsible for producing the hyperdynamic response during early sepsis?

OBJECTIVE: Although polymicrobial sepsis is characterized by an early hyperdynamic phase (2-10 hrs after cecal ligation and puncture [CLP]), followed by a late hypodynamic phase (20 hrs after CLP), it remains unknown whether prostacyclin or prostaglandin I2 (PGI2) plays a significant role in modulating the hyperdynamic state during early sepsis. The aim of this study was to determine whether inhibition of PGI2 synthesis prevents the occurrence of the hyperdynamic response during early sepsis. DESIGN: Prospective, controlled animal study. SETTING: A university research laboratory. SUBJECTS: Adult male Sprague-Dawley rats were subjected to sepsis by CLP. INTERVENTIONS AND MEASUREMENTS: Blood samples were collected at 2, 5, 10, or 20 hrs after CLP, and plasma concentrations of PGI2, in the form of its stable product 6-keto-PGF1alpha, were measured by radioimmunoassay. In additional studies, a PGI2 synthase inhibitor, tranylcypromine, was administered subcutaneously at the time of CLP and again at 3 hrs after CLP. At 5 hrs after the onset of sepsis, the maximal rates of the left ventricular pressure rise (+dP/dtmax) and fall (-dP/dtmax) were determined by an in vivo heart performance analyzer. Microvascular blood flow in the liver, small intestine, and spleen was assessed by laser Doppler flowmetry. MAIN RESULTS: Plasma concentrations of 6-keto-PGF1alpha increased significantly at 2-20 hrs after CLP. At 5 hrs after the onset of sepsis, +/-dP/dt(max) and microvascular blood flow in the tested tissues increased significantly. Inhibition of PGI2 synthase activity did not prevent the occurrence of hypercardiovascular responses under such conditions. Moreover, the administration of tranylcypromine significantly reduced circulating concentrations of 6-keto-PGF1alpha at 5 hrs after CLP. CONCLUSIONS: Because inhibition of PGI2 production did not prevent the occurrence of the hyperdynamic and hypercardiovascular response during the early stage of sepsis, mediators other than PGI2 appear to play a major role in producing the hyperdynamic response under such conditions.     

Interleukin-13 prevents diaphragm muscle deterioration in a septic animal model

The effects of an intravenous injection of Interleukin-13 (IL-13) after endotoxin administration on diaphragm muscle were studied using Wistar rats. Two treatment groups, a control (saline+endotoxin) group and an IL-13 (IL-13+endotoxin) group were studied. E. coli endotoxin (10 mg/kg) was injected intraperitoneally 5 minutes after saline or IL-13 (0.25 microg) injection. The force-frequency curves, twitch kinetics and fatigability were measured at 0 and 4 hours after endotoxin injection. The force-frequency curves and twitch tension in the control group were significantly lower at 4 hours than those at 0 hour due to endotoxin. On the other hand, IL-13 prevented the decrement of the force-frequency curves and twitch tension induced by endotoxin. Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry showed positive staining at 4 hours due to endotoxin in the control group; however, IL-13 also blocked NADPH diaphorase staining at 4 hours. Furthermore, the positive muscle fibers detected by the NADPH diaphorase staining were classified as type I (slow twitch) muscle fibers by ATPase staining. We conclude that IL-13 prevents the deterioration of contraction induced by endotoxin by inhibiting nitric oxide production in the diaphragm muscle, mainly the type I muscle fibers.     

Fasting augments lipid peroxidation during reperfusion after ischemia in the perfused rat liver

OBJECTIVE: To test the hypothesis that fasting would aggravate postischemic lipid peroxidation in a perfused rat liver model. DESIGN: Prospective, randomized study in a rat perfused liver model. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Livers isolated from fed and fasted male Sprague-Dawley rats (n = 16) were exposed to 2.5 hrs of normothermic (38 degrees C) ischemia followed by 2 hrs of reperfusion. MEASUREMENTS AND MAIN RESULTS: Lipid peroxidation was measured by chemiluminescence and thiobarbituric acid reactive substances (TBARS). Injury parameters, potassium, lactate dehydrogenase efflux, and oxygen extraction were measured every 30 mins. Chemiluminescence and TBARS were greater in the fasted ischemic group during reperfusion. (fasted vs. fed: chemiluminescence, 946.8+/-205.5 [SEM] vs. 98.1+/-8.2 counts per second, p = .0004; thiobarbituric acid reactive substances, 1.11+/-0.25 vs. 0.21+/-0.032 nM/g of liver wt/min, p = .0019). Potassium efflux in the fasted group was greater than in the fed group. (1.568+/-0.082 vs. 1.28+/-0.079 microEq/g liver weight/min, p = .0184). Fasted livers extracted less oxygen after ischemia (1.94+/-0.22 vs. 1.14+/-0.46 microM/g liver wt/min, p = .0048). Lactate dehydrogenase levels showed no significant differences. CONCLUSION: Fasting augmented lipid peroxidation markedly. Nutrition may be an important mechanism that protects organs from oxidative injury.     

Attenuation of hyperoxia-induced diaphragmatic dysfunction with lidocaine in hamsters

OBJECTIVE: Toxic free radicals cause dysfunction of respiratory muscles, probably leading to respiratory distress. Exposure to high concentrations of oxygen generates plenty of free radicals. Lidocaine scavenges the reactive molecules. The purposes of the current study were first to examine whether hyperoxia impairs diaphragmatic function, and second, to assess the effects of lidocaine on hyperoxia-induced diaphragmatic dysfunction, if developed. DESIGN: Prospective, randomized animal study. SETTING: University research laboratory. SUBJECTS: Forty and 48 adult male Golden-Syrian hamsters (110-150 g) in parts I and II studies, respectively. INTERVENTION: In the part I study, hyperoxia for 5 and 6 days reduced diaphragmatic contractility and enhanced fatigue. In the part II study, hamsters were randomly allocated to one of six groups (n = 8 each): exposure to air for 6 days with saline (group A-S) or lidocaine infusion (group A-L), exposure to 100% oxygen for 5 days with saline (group 05-S) or lidocaine (group 05-L), and exposure to 100% oxygen for 6 days with saline (group 06-S) or lidocaine (group 06-L). Saline or lidocaine (2 mg/kg/hr) was subcutaneously given immediately before exposure to air or oxygen. Diaphragmatic contractility and fatigability were assessed in vitro using muscle strips excised from the costal diaphragms. Diaphragmatic levels of malondialdehyde (MDA), an index of free radical-mediated lipid peroxidation, were measured. These variables were compared between groups. MEASUREMENTS AND MAIN RESULTS: Twitch and tetanic tensions in groups 05-S and 06-S were reduced compared with group A-S. Tensions generated during fatigue trials were also decreased in groups 05-S and 06-S. MDA levels were elevated in diaphragms from these groups. In groups 05-L and 06-L, contractile dysfunction, deterioration of fatigability, and MDA formation in the diaphragm were attenuated. CONCLUSIONS: Lidocaine attenuated hyperoxia-induced diaphragmatic dysfunction assessed by contractile profiles and fatigability in hamsters. This beneficial effect may be attributable, in part, to inhibition of lipid peroxidation.     

Heparin binding protein increases survival in murine fecal peritonitis

OBJECTIVE: To test the effectiveness of recombinant heparin-binding protein (HBP), a neutrophil-derived multifunctional protein with monocytic-specific properties, in fecal peritonitis and polymicrobial sepsis. DESIGN: Prospective, controlled animal trial. SETTING: Animal research laboratory. SUBJECTS: Swiss Webster mice challenged with cecal ligation and puncture (CLP) and treated with recombinant HBP and 60 mg/kg cefoxitin twice a day. INTERVENTIONS: HBP was administered to mice at different concentrations and different intervals before and after CLP. Rat albumin (1%) was administered to control animals. MEASUREMENTS AND MAIN RESULTS: MORTALITY RATE: Survival was increased in mice pretreated intraperitoneally 24 hrs before CLP with 10 microg or 100 microg of HBP without cefoxitin (p = .01, Cox-Mantel log-rank test). Compared with control animals, survival was increased significantly (from 5% to 47%, p = .014) in mice that received cefoxitin and 50 microg ip HBP immediately after CLP, followed by continuous administration of HBP (12 microg/24 hrs). Intravenous administration of HBP (0.1, 1, and 10 microg) at the time of CLP showed an opposite dose effect; low doses (0.1 microg) prolonged early survival, whereas high dose (10 microg) shortened survival (p = .036). Compared with control animals, overall survival was not different. CHEMOTAXIS: Cytospin preparations from peritoneal exudate cells (PECs) 48 hrs after administration of 10 microg and 100 microg ip HBP demonstrated a 1.7-fold increase in the total number of macrophages compared with carrier control (p < .05). PHAGOCYTOSIS: A flow cytometric in vitro assay demonstrated that administration of 10 microg ip HBP alone did not enhance phagocytosis of fluorescent Escherichia coli in PECs. However, 24-hr pretreatment with 10 microg of HBP followed by CLP increased phagocytosis in PECs 1.8-fold compared with the control CLP group (p = .04). RECEPTOR EXPRESSION: CD16/CD32w expression in PECs did not change after HBP or CLP. CD11b and CD18 expression in PECs was increased significantly after CLP compared with PECs from non-CLP-challenged animals (p < .05). Pretreatment with 10 microg of HBP did not further enhance CD11b/CD18 expression in PECs. CONCLUSIONS: Recombinant HBP increases survival in murine fecal peritonitis. The mechanisms by which HBP reduces septic death are not fully understood, but they include monocyte chemotaxis and increased phagocytosis of E. coli by PECs. Our data suggest that the inflammatory response induced by CLP is important for the effect of HBP to enhance phagocytosis.     

ONO-1714, a new inducible nitric oxide synthase inhibitor, attenuates diaphragmatic dysfunction associated with cerulein-induced pancreatitis in rats

OBJECTIVES: Acute experimental pancreatitis (induced by cerulein) recently has been reported to cause marked diaphragmatic dysfunction, which may contribute to respiratory distress in this setting. In cerulein-induced acute pancreatitis, expression of inducible nitric oxide synthase is induced to produce a large amount of nitric oxide. Nitric oxide excessively produced has been implicated in diaphragmatic dysfunction induced by a variety of etiologies. The aims of the current study were, first, to examine whether nitric oxide overproduced through inducible nitric oxide synthase is involved in cerulein-induced impairment of diaphragmatic function, and second, if demonstrated, to assess effects of ONO-1714, an inducible nitric oxide synthase inhibitor, on diaphragmatic dysfunction associated with cerulein-induced acute pancreatitis. DESIGN: Prospective, randomized animal study. SETTING: University research laboratory. SUBJECTS: Ninety-one male Sprague-Dawley rats, weighing 200-250 g. INTERVENTIONS: Rats were randomly divided into seven groups (n = 8 each): CONT-SAL, CAER-SAL, CONT-ONO, CAER-DEX, CAER-AMI, CAER-ONOhigh, and CAER-ONOlow. Groups labeled CAER received two consecutive intraperitoneal doses (50 microg/kg) of cerulein, whereas groups labeled CONT received two consecutive intraperitoneal injections of saline. Groups labeled SAL received intraperitoneal saline before cerulein or saline. The group labeled DEX received 2 mg/kg intraperitoneal dexamethasone, and the group labeled AMI received 100 mg/kg intraperitoneal aminoguanidine. The groups labeled ONO, ONOhigh, and ONOlow received ONO-1714 at 0.1 mg/kg, 0.1 mg/kg, and 0.03 mg/kg, respectively, before cerulein or saline. MEASUREMENTS AND MAIN RESULTS: Diaphragmatic contractility and fatigability were assessed in vitro by using muscle strips excised from the costal diaphragms 6 hrs after the first dose of cerulein or saline. Expression of inducible nitric oxide synthase protein in the diaphragm was assessed by immunohistochemistry by using anti-inducible nitric oxide synthase antibody. Plasma concentrations of nitrite plus nitrate and diaphragmatic concentrations of malondialdehyde were measured. With another set of rats (n = 5 each group), diaphragmatic inducible nitric oxide synthase activity was determined. Twitch and tetanic tensions and tensions generated during fatigue trial were lower in group CAER-SAL than in group CONT-SAL. Cerulein increased diaphragmatic malondialdehyde and plasma nitrite plus nitrate concentrations. Positive immunostaining for inducible nitric oxide synthase protein was found in group CAER-SAL. Dexamethasone and aminoguanidine attenuated the diaphragmatic mechanical damages. A high dose of ONO-1714 attenuated cerulein-induced impairment of diaphragmatic contractility and endurance capacity, although a low dose of the drug failed to do so. CONCLUSIONS: Cerulein-induced diaphragmatic dysfunction was attributable, in part, to nitric oxide overproduced via inducible nitric oxide synthase. Pretreatment with ONO-1714 at a dose of 0.1 mg/kg attenuated diaphragmatic dysfunction associated with cerulein-induced pancreatitis in rats assessed by contractile profiles and endurance capacity. This beneficial effect of ONO-1714 may be attributable, in part, to inhibition of diaphragmatic lipid peroxidation induced by nitric oxide-derived free radicals.     

Hyperbaric oxygen protects from sepsis mortality via an interleukin-10-dependent mechanism

OBJECTIVE: This study was performed to determine whether hyperbaric oxygen (HBO2) therapy is protective in cecal ligation and puncture (CLP)-induced sepsis and if protection is dependent on oxygen dosing. We also wished to determine whether HBO2 affected bacterial clearance or altered macrophage production of interleukin-10 (IL-10)s in the setting of CLP sepsis. Finally, we wished to determine whether the mechanism of HBO2 protection in sepsis was dependent on IL-10 production. DESIGN: Prospective, experimental study. SETTING: University experimental research laboratory. SUBJECTS: C57BL/6 and C57BL/6 IL-10 mice. INTERVENTIONS: Sepsis was induced by CLP. Mice were randomized to receive a 1.5-hr HBO2 treatment at either 1, 2.5, or 3 atmospheres absolute every 12 hrs or HBO2 at 2.5 atmospheres absolute every 24 hrs. Mice were also harvested at 24 hrs for determination of bacterial load and isolation and study of CD11b peritoneal macrophages. MEASUREMENTS AND MAIN RESULTS: Survival was monitored for 100 hrs after CLP +/- HBO2 treatment. HBO2 significantly improved survival when administered at 2.5 atmospheres absolute every 12 hrs. Other treatment schedules were not protective, and treatment at 3.0 atmospheres absolute significantly worsened survival outcome. Bacterial load was significantly reduced in splenic homogenates but not peritoneal fluid at 24 hrs. Macrophages isolated from HBO2-treated mice demonstrated enhanced IL-10 secretion in response to lipopolysaccharide as compared with CLP controls. Mice genetically deficient in IL-10 expression treated with HBO2 at 2.5 atmospheres absolute every 12 hrs were not protected from CLP-induced mortality. CONCLUSION: HBO2 may be protective in CLP sepsis within a window of oxygen dosing. The mechanism of HBO2 protection may be potentially linked in part to expression of IL-10, as peritoneal macrophages demonstrated enhanced IL-10 expression and IL-10 mice were not protected by HBO2 treatment.     

The anti-inflammatory effect of curcumin in an experimental model of sepsis is mediated by up-regulation of peroxisome proliferator-activated receptor-gamma

OBJECTIVE: Although phytochemical curcumin has been shown to possess anti-inflammatory properties, it remains unknown whether this agent has any beneficial effects in sepsis. The purpose of this study was to demonstrate whether curcumin protects septic animals and, if so, whether activation of peroxisome proliferator-activated receptor (PPAR)-gamma, an anti-inflammatory nuclear receptor, plays any role. DESIGN: Prospective, controlled, and randomized animal study. SETTING: A research institute laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: A bolus injection of 0.2 micromol of curcumin was given intravenously to male adult rats, followed by continuous infusion of curcumin (0.24 micromol/day) for 3 days via a primed 2-mL mini-pump. The rats were then subjected to sepsis by cecal ligation and puncture (CLP). MEASUREMENTS AND MAIN RESULTS: Serum levels of liver enzymes (alanine aminotransferase and aspartate aminotransferase), lactate, albumin, and tumor necrosis factor (TNF)-alpha were measured at 20 hrs after CLP (i.e., late stage of sepsis). In addition, a 10-day survival curve was conducted following CLP and cecal excision with or without curcumin treatment. Furthermore, macrophages cell line RAW 264.7 cells were treated with curcumin followed by stimulation with endotoxin. TNF-alpha and PPAR-gamma expression were then measured. The results indicate that intravenous administration of curcumin before the onset of sepsis attenuated tissue injury, reduced mortality, and decreased the expression of TNF-alpha in septic animals. Similar results were also found when curcumin was administered after the onset of sepsis. Moreover, the down-regulated PPAR-gamma in the liver at 20 hrs after CLP was significantly improved by curcumin treatment. Concurrent administration of curcumin and GW9662, a specific PPAR-gamma antagonist, completely abolished the beneficial effects of curcumin under such conditions. In cultured RAW 264.7 cells, curcumin inhibited endotoxin-induced increases in TNF-alpha expression and markedly up-regulated PPAR-gamma expression without affecting cell viability. Curcumin also prevented morphologic alterations in macrophages induced by endotoxin. CONCLUSIONS: The protective effect of curcumin makes it or its analogues strong candidates as a novel therapy for sepsis. The beneficial effect of curcumin appears to be mediated by up-regulation of nuclear receptor PPAR-gamma.     

The activity of tissue factor pathway inhibitor in experimental models of superantigen-induced shock and polymicrobial intra-abdominal sepsis

OBJECTIVES: To study recombinant human tissue factor pathway inhibitor (rhTFPI) in a superantigen-induced shock model and in a cecal ligation and puncture (CLP) model of peritonitis in mice. DESIGN: Prospective, randomized, experimental study. SETTING: An experimental animal research laboratory. SUBJECTS: Eighty BALB/c mice for the superantigen model, and 56 BALB/c mice for the CLP model. INTERVENTIONS: In the superantigen-induced shock model, animals received rhTFPI (350 mg/kg) subcutaneously every 12 hrs (n = 30) or saline control (n = 30) for 60 hrs after staphylococcal enterotoxin B (SEB; 10 microg iv) and a sublethal dose of E. coli 0111:B4 lipopolysaccharide (LPS; 75 microg ip). Control groups received SEB alone (n = 10) and LPS alone (n = 10). In the CLP model, rhTFPI or saline was given every 8 hrs for 48 hrs by using a 21-gauge needle (n = 9) or 23-gauge needle (n = 14) for CLP. A sham surgery control group (n = 10) was also included. MEASUREMENTS AND MAIN RESULTS: There was 0% mortality in the SEB and LPS control groups. The mortality rate was 64% in the saline control group that received both SEB and LPS (19 of 30), whereas the rhTFPI- treated animals had a mortality rate of 20% (6 of 30; p < .01). The rhTFPI-treated group had significantly lower interleukin-6 levels (61.8 +/- 41 pg/mL vs. 285 +/- 63 pg/mL; p < .05) than the control group but no differences in tumor necrosis factor-alpha or interferon-gamma levels. In the CLP experiment, rhTFPI-treated animals did not have any survival advantage over the control group after the large-bore (21-gauge) needle puncture. The rhTFPI group had significantly improved 7-day mortality rate after CLP with the small-bore needle (23-gauge; 21.4% [rhTFPI] vs. 71.4% [control], p < .01). Plasma LPS, interleukin-6, interferon-gamma, and tumor necrosis factor-alpha levels were unchanged by rhTFPI treatment, but significantly reduced LPS (p = .006) and IFNgamma (p = .001) levels were found in the peritoneal fluid. CONCLUSIONS: Tissue factor pathway inhibitor significantly improves the mortality rate in models of superantigen-induced shock and polymicrobial intra-abdominal infection, supporting its potential use in clinical trials for septic shock.     

Measurement of twitch transdiaphragmatic, esophageal, and endotracheal tube pressure with bilateral anterolateral magnetic phrenic nerve stimulation in patients in the intensive care unit.

OBJECTIVE: In the critically ill, respiratory muscle strength usually has been assessed by measuring maximum inspiratory pressure. The maneuver is volitional, and results can be unreliable. The nonvolitional technique of bilateral anterolateral magnetic stimulation of the phrenic nerves, producing twitch transdiaphragmatic pressure, has been successful in normal subjects and ambulatory patients. In this study we used the technique in the intensive care unit and explored the measurement of twitch endotracheal tube pressure as a less invasive technique to assess diaphragmatic contractility. DESIGN: Clinical study to quantify diaphragm strength in the intensive care unit. SETTING: Patients from three London teaching hospital intensive care units and high-dependency units. PATIENTS: Forty-one intensive care patients were recruited. Of these, 33 (20 men, 13 women) were studied. INTERVENTIONS: Esophageal and gastric balloon catheters were passed through the anaesthetized nose, and an endotracheal tube occlusion device was placed in the ventilation circuit, next to the endotracheal tube. Two 43-mm magnetic coils were placed anteriorly on the patient's neck, and the phrenic nerves were stimulated magnetically. MEASUREMENTS AND MAIN RESULTS: On phrenic nerve stimulation, twitch gastric pressure, twitch esophageal pressure, twitch transdiaphragmatic pressure, and twitch endotracheal tube pressure were measured. Forty-one consecutive patients consented to take part in the study, and twitch pressure data were obtained in 33 of these. Mean transdiaphragmatic pressure was 10.7 cm H2O, mean twitch esophageal pressure was 6.7 cm H2O, and mean twitch endotracheal tube pressure was 6.7 cm H2O. The mean difference between twitch esophageal pressure and twitch endotracheal tube pressure was 0.02 cm H2O. Correlation of the means of twitch endotracheal tube pressure to twitch esophageal pressure was 0.93, and that for twitch endotracheal tube pressure to transdiaphragmatic pressure was 0.78. CONCLUSIONS: Transdiaphragmatic pressure can be measured in the critically ill to give a nonvolitional assessment of diaphragm contractility, but not all patients can be studied. At present, the relationship of twitch endotracheal tube pressure to transdiaphragmatic pressure is too variable to reliably represent a less invasive measure of diaphragm strength.     

Cognitive impairment in sepsis survivors from cecal ligation and perforation

OBJECTIVE: Critical illness survivors present long-term cognitive impairment, including problems with memory and learning. We evaluated cognitive performance in rats that survived from sepsis induced by cecal ligation and puncture (CLP). DESIGN: Prospective, controlled experiment. SETTING: Animal basic science laboratory. SUBJECTS: Male Wistar rats, weighing 300-350 g. INTERVENTIONS: The rats underwent CLP (sepsis group) with "basic support" (saline at 50 mL/kg immediately and 12 hrs after CLP plus ceftriaxone at 30 mg/kg and clindamycin at 25 mg/kg 6, 12, and 18 hrs after CLP) or sham-operated (control group). MEASUREMENTS AND MAIN RESULTS: Ten days after surgery, the animals underwent three behavioral tasks: a) inhibitory avoidance task; b) habituation to an open field; and c) continuous multiple-trials step-down inhibitory avoidance task (CMSIA). In the habituation to an open-field task, there were no differences in the number of crossings and rearings. The sepsis group showed significantly decreased performance in latency retention compared with the sham group in inhibitory avoidance. Furthermore, when tested by the habituation to an open-field task, the sepsis group did not show any difference between training and test, indicating memory impairment. In the CMSIA, the sepsis group showed a significant increase in the number of training trials required to reach the acquisition criterion. CONCLUSION: Our data provide the first experimental demonstration that survivors from CLP show learning and memory impairment after complete physical recovery from sepsis.