Effects of Sodium Thiosulfate During Resuscitation From Trauma-and-Hemorrhage in Cystathionine-γ-Lyase Knockout Mice With Diabetes Type 1.

Background: Sodium thiosulfate (STS) is a recognized drug with antioxidant and H2S releasing properties. We recently showed that STS attenuated organ dysfunction and injury during resuscitation from trauma-and-hemorrhage in CSE-ko mice, confirming its previously described organ-protective and anti-inflammatory properties. The role of H2S in diabetes mellitus type 1 (DMT1) is controversial: genetic DMT1 impairs H2S biosynthesis, which has been referred to contribute to endothelial dysfunction and cardiomyopathy. In contrast, development and severity of hyperglycemia in streptozotocin(STZ)-induced DMT1 was attenuated in CSE-ko mice. Therefore, we tested the hypothesis whether STS would also exert organ-protective effects in CSE-ko mice with STZ-induced DMT1, similar to our findings in animals without underlying co-morbidity. Methods: Under short-term anesthesia with sevoflurane and analgesia with buprenorphine CSE-ko mice underwent DMT1-induction by single STZ injection (100 µg⋅g-1). Seven days later, animals underwent blast wave-induced blunt chest trauma and surgical instrumentation followed by 1 h of hemorrhagic shock (MAP 35 ± 5 mmHg). Resuscitation comprised re-transfusion of shed blood, lung-protective mechanical ventilation, fluid resuscitation and continuous i.v. norepinephrine together with either i.v. STS (0.45 mg⋅g-1) or vehicle (n = 9 in each group). Lung mechanics, hemodynamics, gas exchange, acid-base status, stable isotope-based metabolism, and visceral organ function were assessed. Blood and organs were collected for analysis of cytokines, chemokines, and immunoblotting. Results: Diabetes mellitus type 1 was associated with more severe circulatory shock when compared to our previous study using the same experimental design in CSE-ko mice without co-morbidity. STS did not exert any beneficial therapeutic effect. Most of the parameters measured of the inflammatory response nor the tissue expression of marker proteins of the stress response were affected either. Conclusion: In contrast to our previous findings in CSE-ko mice without underlying co-morbidity, STS did not exert any beneficial therapeutic effect in mice with STZ-induced DMT1, possibly due to DMT1-related more severe circulatory shock. This result highlights the translational importance of both integrating standard ICU procedures and investigating underlying co-morbidity in animal models of shock research.

Effects of Sodium Thiosulfate During Resuscitation From Trauma-and-Hemorrhage in Cystathionine Gamma Lyase (CSE) Knockout Mice.

BACKGROUND: Sodium thiosulfate (Na2S2O3) is a clinically established drug with antioxidant and sulphide-releasing properties. Na2S2O3 mediated neuro- and cardioprotective effects in ischemia/reperfusion models and anti-inflammatory effects in LPS-induced acute lung injury. Moreover, Na2S2O3 improved lung function during resuscitation from hemorrhagic shock in swine with pre-existing atherosclerosis, characterized by decreased expression of cystathionine γ-lyase (CSE), a major source of hydrogen sulfide (H2S) synthesis in the vasculature. Based on these findings, we investigated the effects of Na2S2O3 administration during resuscitation from trauma-and-hemorrhage in mice under conditions of whole body CSE deficit. METHODS: After blast wave-induced blunt chest trauma and surgical instrumentation, CSE knockout (CSE-/-) mice underwent 1 h of hemorrhagic shock (MAP 35 ±â€Š5 mm Hg). At the beginning of resuscitation comprising retransfusion, norepinephrine support and lung-protective mechanical ventilation, animals received either i.v. Na2S2O3 (0.45 mg g-1, n = 12) or vehicle (saline, n = 13). Hemodynamics, acid-base status, metabolism using stable isotopes, and visceral organ function were assessed. Blood and organs were collected for analysis of cytokines, mitochondrial respiratory capacity, and immunoblotting. RESULTS: Na2S2O3 treatment improved arterial paO2 (P = 0.03) coinciding with higher lung tissue glucocorticoid receptor expression. Norepinephrine requirements were lower in the Na2S2O3 group (P < 0.05), which was associated with lower endogenous glucose production and higher urine output. Na2S2O3 significantly increased renal tissue IκBα and heme oxygenase-1 expression, whereas it lowered kidney IL-6 and MCP-1 levels. CONCLUSION: Na2S2O3 exerted beneficial effects during resuscitation of murine trauma-and-hemorrhage in CSE-/- mice, confirming and extending the previously described organ-protective and anti-inflammatory properties of Na2S2O3. The findings make Na2S2O3 a potentially promising therapeutic option in the context of impaired CSE activity and/or reduced endogenous H2S availability.

Cardiac Effects of Hyperoxia During Resuscitation From Hemorrhagic Shock in Swine.

Hyperoxia (ventilation with FIO2 = 1.0) has vasoconstrictor properties, in particular in the coronary vascular bed, and, hence, may promote cardiac dysfunction. However, we previously showed that hyperoxia attenuated myocardial injury during resuscitation from hemorrhage in swine with coronary artery disease. Therefore, we tested the hypothesis whether hyperoxia would also mitigate myocardial injury and improve heart function in the absence of chronic cardiovascular comorbidity.After 3 h of hemorrhage (removal of 30% of the calculated blood volume and subsequent titration of mean arterial pressure to 40 mm Hg) 19 anesthetized, mechanically ventilated, and instrumented pigs received FIO2 = 0.3(control) or hyperoxia(FIO2 = 1.0) during the first 24 h. Before, at the end of and every 12 h after shock, hemodynamics, blood gases, metabolism, cytokines, and cardiac function (pulmonary artery thermodilution, left ventricular pressure-conductance catheterization) were recorded. At 48 h, cardiac tissue was harvested for western blotting, immunohistochemistry, and mitochondrial respiration.Except for higher left ventricular end-diastolic pressures at 24 h (hyperoxia 21 (17;24), control 17 (15;18) mm Hg; P = 0.046), hyperoxia affected neither left ventricular function cardiac injury (max. Troponin I at 12 h: hyperoxia:9 (6;23), control:17 (11;24) ng mL; P = 0.395), nor plasma cytokines (except for interleukin-1ß: hyperoxia 10 (10;10) and 10 (10;10)/control 14 (10;22), 12 (10;15) pg mL, P = 0.023 and 0.021 at 12 and 24 h, respectively), oxidation and nitrosative stress, and mitochondrial respiration. However, hyperoxia decreased cardiac tissue three-nitrotyrosine formation (P < 0.001) and inducible nitric oxide synthase expression (P = 0.016). Ultimately, survival did not differ significantly either.In conclusion, in contrast to our previous study in swine with coronary artery disease, hyperoxia did not beneficially affect cardiac function or tissue injury in healthy swine, but was devoid of deleterious side effects.

Effects of Hyperoxia During Resuscitation From Hemorrhagic Shock in Swine With Preexisting Coronary Artery Disease.

OBJECTIVES: Investigation of the effects of hyperoxia during resuscitation from hemorrhagic shock in swine with preexisting coronary artery disease. DESIGN: Prospective, controlled, randomized trial. SETTING: University animal research laboratory. SUBJECTS: Nineteen hypercholesterolemic pigs with preexisting coronary artery disease. INTERVENTIONS: Anesthetized, mechanically ventilated, and surgically instrumented pigs underwent 3 hours of hemorrhagic shock (removal of 30% of the calculated blood volume and subsequent titration of mean arterial blood pressure ≈40 mm Hg). Postshock resuscitation (48 hr) comprised retransfusion of shed blood, crystalloids (balanced electrolyte solution), and norepinephrine support. Pigs were randomly assigned to "control" (FIO2 0.3, adjusted for arterial oxygen saturation ≥ 90%) and "hyperoxia" (FIO2 1.0 for 24 hr) groups. MEASUREMENTS AND MAIN RESULTS: Before, at the end of shock and every 12 hours of resuscitation, datasets comprising hemodynamics, calorimetry, blood gases, cytokines, and cardiac and renal function were recorded. Postmortem, organs were sampled for immunohistochemistry, western blotting, and mitochondrial high-resolution respirometry. Survival rates were 50% and 89% in the control and hyperoxia groups, respectively (p = 0.077). Apart from higher relaxation constant τ at 24 hours, hyperoxia did not affect cardiac function. However, troponin values were lower (2.2 [0.9-6.2] vs 6.9 [4.8-9.8] ng/mL; p < 0.05) at the end of the experiment. Furthermore, hyperoxia decreased cardiac 3-nitrotyrosine formation and increased inducible nitric oxide synthase expression. Plasma creatinine values were lower in the hyperoxia group during resuscitation coinciding with significantly improved renal mitochondrial respiratory capacity and lower 3-nitrotyrosine formation. CONCLUSIONS: Hyperoxia during resuscitation from hemorrhagic shock in swine with preexisting coronary artery disease reduced renal dysfunction and cardiac injury, potentially resulting in improved survival, most likely due to increased mitochondrial respiratory capacity and decreased oxidative and nitrosative stress. Compared with our previous study, the present results suggest a higher benefit of hyperoxia in comorbid swine due to an increased susceptibility to hemorrhagic shock.

Impact of hyperglycemia on cystathionine-γ-lyase expression during resuscitated murine septic shock.

BACKGROUND: Cystathionine-γ-lyase (CSE) was shown to have a regulatory role in glucose metabolism. Circulatory shock can induce metabolic stress, thereby leading to hyperglycemia and mitochondrial dysfunction. In vitro data suggest an effect of high glucose on CSE expression. Therefore, the aim of this study was to investigate the effects of hyperglycemia on CSE expression in resuscitated murine septic shock. METHODS: Normo- (80-150 mg/dl) and hyperglycemic (>200 mg/dl) male C57/BL6J mice (n = 5-6 per group) underwent cecal ligation and puncture (CLP)-induced polymicrobial sepsis or sham procedure (n = 6 per group) and, 15 h afterwards, were anesthetized again, surgically instrumented and received intensive care treatment, including antibiotics, lung protective mechanical ventilation, circulatory support, and intravenous (i.v.) glucose infusion (50% as stable-isotope labeled 1,2,3,4,5,6-13C6 glucose). Blood and breath gas were sampled hourly to quantify parameters of glucose metabolism. 5 h later, mice were sacrificed and organs were harvested. The liver mitochondrial respiratory activity was determined via high resolution respirometry; CSE, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), and adipocyte differentiation-related protein (ADRP) expression was immunohistochemically investigated. RESULTS: In sepsis combined with hyperglycemia the least CSE and PGC1α expression could be detected, along with reduced mitochondrial respiratory activity, and enhanced ADRP expression, a marker of lipid droplet formation, in the liver. A novel in vivo finding is the CSE translocation from the cytosol to the nucleus triggered by metabolic stress. CONCLUSIONS: A relationship between CSE and glucose metabolism was established, which, when dysregulated, may contribute to fatty liver disease and hepatic steatosis.

Hyperoxia or Therapeutic Hypothermia During Resuscitation from Non-Lethal Hemorrhagic Shock in Swine.

We previously demonstrated beneficial effects of 22 h of hyperoxia following near-lethal porcine hemorrhagic shock, whereas therapeutic hypothermia was detrimental. Therefore, we investigated whether shorter exposure to hyperoxia (12 h) would still improve organ function, and whether 12 h of hypothermia with subsequent rewarming could avoid deleterious effects after less severe hemorrhagic shock.Twenty-seven anesthetized and surgically instrumented pigs underwent 3 h of hemorrhagic shock by removal of 30% of the blood volume and titration of the mean arterial blood pressure (MAP) to 40 mm Hg. Post-shock, pigs were randomly assigned to control, hyperoxia (FIO2 100% for 12 h) or hypothermia group (34°C core temperature for 12 h with subsequent rewarming). Before, at the end of shock, after 12 and 23 h of resuscitation, data sets comprising hemodynamics, blood gases, and parameters of inflammation and organ function were acquired. Postmortem, kidney samples were collected for immunohistochemistry and western blotting.Hyperoxia exerted neither beneficial nor detrimental effects. In contrast, mortality in the hypothermia group was significantly higher compared with controls (67% vs. 11%). Hypothermia impaired circulation (MAP 64 (57;89) mm Hg vs. 104 (98; 114) mm Hg) resulting in metabolic acidosis (lactate 11.0 (6.6;13.6) mmol L vs. 1.0 (0.8;1.5) mmol L) and reduced creatinine clearance (26 (9;61) mL min vs. 77 (52;80) mL min) compared to the control group after 12 h of resuscitation. Impaired kidney function coincided with increased renal 3-nitrotyrosine formation and extravascular albumin accumulation.In conclusion, hyperoxia proved to be safe during resuscitation from hemorrhagic shock. The lacking organ-protective effects of hyperoxia compared to resuscitation from near-lethal hemorrhage suggest a dependence of the effectiveness of hyperoxia from shock severity. In line with our previous report, therapeutic hypothermia (and rewarming) was confirmed to be detrimental most likely due to vascular barrier dysfunction.

Prehepatic secretion and disposal of insulin in obese adolescents as estimated by three-hour, eight-sample oral glucose tolerance tests.

The body compensates for early-stage insulin resistance by increasing insulin secretion. A reliable and easy-to-use mathematical assessment of insulin secretion and disposal could be a valuable tool for identifying patients at risk for the development of type 2 diabetes. Because the pathophysiology of insulin resistance is incompletely understood, assessing insulin metabolism with minimal assumptions regarding its metabolic regulation is a major challenge. To assess insulin secretion and indexes of insulin disposal, our marginalized and regularized absorption approach (MRA) was applied to a sparse sampling oral glucose tolerance test (OGTT) protocol measuring the insulin and C-peptide concentrations. Identifiability and potential bias of metabolic parameters were estimated from published data with dense sampling. The MRA was applied to OGTT data from 135 obese adolescents to demonstrate its clinical applicability. Individual prehepatic basal and dynamic insulin secretion and clearance levels were determined with a precision and accuracy greater than 10% of the nominal value. The intersubject variability in these parameters was approximately four times higher than the intrasubject variability, and there was a strong negative correlation between prehepatic secretion and plasma clearance of insulin. MRA-based analysis provides reliable estimates of insulin secretion and clearance, thereby enabling detailed glucose homeostasis characterization based on restricted datasets that are obtainable during routine patient care.

Effects of Hyperoxia and Mild Therapeutic Hypothermia During Resuscitation From Porcine Hemorrhagic Shock.

OBJECTIVE: Hemorrhagic shock-induced tissue hypoxia induces hyperinflammation, ultimately causing multiple organ failure. Hyperoxia and hypothermia can attenuate tissue hypoxia due to increased oxygen supply and decreased demand, respectively. Therefore, we tested the hypothesis whether mild therapeutic hypothermia and hyperoxia would attenuate postshock hyperinflammation and thereby organ dysfunction. DESIGN: Prospective, controlled, randomized study. SETTING: University animal research laboratory. SUBJECTS: Thirty-six Bretoncelles-Meishan-Willebrand pigs of either gender. INTERVENTIONS: After 4 hours of hemorrhagic shock (removal of 30% of the blood volume, subsequent titration of mean arterial pressure at 35 mm Hg), anesthetized and instrumented pigs were randomly assigned to "control" (standard resuscitation: retransfusion of shed blood, fluid resuscitation, norepinephrine titrated to maintain mean arterial pressure at preshock values, mechanical ventilation titrated to maintain arterial oxygen saturation > 90%), "hyperoxia" (standard resuscitation, but FIO2, 1.0), "hypothermia" (standard resuscitation, but core temperature 34°C), or "combi" (hyperoxia plus hypothermia) (n = 9 each). MEASUREMENTS AND MAIN RESULTS: Before, immediately at the end of and 12 and 22 hours after hemorrhagic shock, we measured hemodynamics, blood gases, acid-base status, metabolism, organ function, cytokine production, and coagulation. Postmortem kidney specimen were taken for histological evaluation, immunohistochemistry (nitrotyrosine, cystathionine γ-lyase, activated caspase-3, and extravascular albumin), and immunoblotting (nuclear factor-κB, hypoxia-inducible factor-1α, heme oxygenase-1, inducible nitric oxide synthase, B-cell lymphoma-extra large, and protein expression of the endogenous nuclear factor-κB inhibitor). Although hyperoxia alone attenuated the postshock hyperinflammation and thereby tended to improve visceral organ function, hypothermia and combi treatment had no beneficial effect. CONCLUSIONS: During resuscitation from near-lethal hemorrhagic shock, hyperoxia attenuated hyperinflammation, and thereby showed a favorable trend toward improved organ function. The lacking efficacy of hypothermia was most likely due to more pronounced barrier dysfunction with vascular leakage-induced circulatory failure.

Effects of glycemic control on glucose utilization and mitochondrial respiration during resuscitated murine septic shock.

BACKGROUND: This study aims to test the hypothesis whether lowering glycemia improves mitochondrial function and thereby attenuates apoptotic cell death during resuscitated murine septic shock. METHODS: Immediately and 6 h after cecal ligation and puncture (CLP), mice randomly received either vehicle or the anti-diabetic drug EMD008 (100 µg · g(-1)). At 15 h post CLP, mice were anesthetized, mechanically ventilated, instrumented and rendered normo- or hyperglycemic (target glycemia 100 ± 20 and 180 ± 50 mg · dL(-1), respectively) by infusing stable, non-radioactive isotope-labeled (13)C6-glucose. Target hemodynamics was achieved by colloid fluid resuscitation and continuous i.v. noradrenaline, and mechanical ventilation was titrated according to blood gases and pulmonary compliance measurements. Gluconeogenesis and glucose oxidation were derived from blood and expiratory glucose and (13)CO2 isotope enrichments, respectively; mathematical modeling allowed analyzing isotope data for glucose uptake as a function of glycemia. Postmortem liver tissue was analyzed for HO-1, AMPK, caspase-3, and Bax (western blotting) expression as well as for mitochondrial respiratory activity (high-resolution respirometry). RESULTS: Hyperglycemia lowered mitochondrial respiratory capacity; EMD008 treatment was associated with increased mitochondrial respiration. Hyperglycemia decreased AMPK phosphorylation, and EMD008 attenuated both this effect as well as the expression of activated caspase-3 and Bax. During hyperglycemia EMD008 increased HO-1 expression. During hyperglycemia, maximal mitochondrial oxidative phosphorylation rate was directly related to HO-1 expression, while it was unrelated to AMPK activation. According to the mathematical modeling, EMD008 increased the slope of glucose uptake plotted as a function of glycemia. CONCLUSIONS: During resuscitated, polymicrobial, murine septic shock, glycemic control either by reducing glucose infusion rates or EMD008 improved glucose uptake and thereby liver tissue mitochondrial respiratory activity. EMD008 effects were more pronounced during hyperglycemia and coincided with attenuated markers of apoptosis. The effects of glucose control were at least in part due to the up-regulation of HO-1 and activation of AMPK.

Multivariate determination of 13CO2/12CO2 ratios in exhaled mouse breath with mid-infrared hollow waveguide gas sensors.

The (12)CO2/(13)CO2 isotope ratio is a well-known marker in breath for a variety of biochemical processes and enables monitoring, e.g., of the glucose metabolism during sepsis. Using animal models-here, at a mouse intensive care unit-the simultaneous determination of (12)CO2 and (13)CO2 within small volumes of mouse breath was enabled by coupling a novel low-volume hollow waveguide gas cell to a compact Fourier transform infrared spectrometer combined with multivariate data evaluation based on partial least squares regression along with optimized data preprocessing routines.

Effects of pretreatment hypothermia during resuscitated porcine hemorrhagic shock.

OBJECTIVES: Accidental hypothermia increases mortality and morbidity after hemorrhage, but controversial data are available on the effects of therapeutic hypothermia. Therefore, we tested the hypothesis whether moderate pretreatment hypothermia would beneficially influence organ dysfunction during long-term, porcine hemorrhage and resuscitation. DESIGN: Prospective, controlled, randomized study. SETTING: University animal research laboratory. SUBJECTS: Twenty domestic pigs of either gender. INTERVENTIONS: Using an extracorporeal heat exchanger, anesthetized and instrumented animals were maintained at 38°C, 35°C, or 32°C core temperature and underwent 4 hours of hemorrhage (removal of 40% of the blood volume and subsequent blood removal/retransfusion to maintain mean arterial pressure at 30 mm Hg). Resuscitation comprised of hydroxyethyl starch and norepinephrine infusion titrated to maintain mean arterial pressure at preshock values. MEASUREMENTS AND MAIN RESULTS: Before, immediately at the end of, and 12 and 22 hours after hemorrhage, we measured systemic and regional hemodynamics (portal vein, hepatic and right kidney artery ultrasound flow probes) and oxygen transport, and nitric oxide and cytokine production. Hemostasis was assessed by rotation thromboelastometry. Postmortem biopsies were analyzed for histomorphology (hematoxylin and eosin staining) and markers of apoptosis (kidney Bcl-xL and caspase-3 expression). Hypothermia at 32°C attenuated the shock-related lactic acidosis but caused metabolic acidosis, most likely resulting from reduced carbohydrate oxidation. Although hypothermia did not further aggravate shock-related coagulopathy, it caused a transitory attenuation of kidney and liver dysfunction, which was ultimately associated with reduced histological damage and more pronounced apoptosis. CONCLUSIONS: During long-term porcine hemorrhage and resuscitation, moderate pretreatment hypothermia was associated with a transitory attenuation of organ dysfunction and less severe histological tissue damage despite more pronounced metabolic acidosis. This effect is possibly due to a switch from necrotic to apoptotic cell death, ultimately resulting from reduced tissue energy deprivation during the shock phase.

Estimation of parameters for the elimination of an orally administered test substance with unknown absorption.

Assessment of the elimination of an oral test dose based on plasma concentration values requires correction for the effect of gastric release and absorption. Irregular uptake processes should be described 'model independently', which requires estimation of a large number of absorption parameters. To limit the associated computational effort a new approach is developed with a reduced number of unknown parameters. A marginalized and regularized absorption approach (MRA) is defined, which uses for the uptake just one parameter to control rigidity of the uptake curve. For validation, elimination and absorption were reproduced using published IVIVC data and a synthetic data set for comparison with approaches using a 'model-free'--staircase function or mechanistic models to describe absorption. MRA performed almost as accurate as well specified mechanistic models, which gave the best reproduction. MRA demonstrated a 50fold increase in computational efficiency compared to other approaches. The absorption estimated for the IVIVC study demonstrated an in vivo-in vitro correlation comparable to published values. The newly developed MRA approach can be used to efficiently and accurately estimate elimination and absorption with a restricted number of adaptive parameters and with automatic adjustment of the complexity of the uptake.

Adrenomedullin binding improves catecholamine responsiveness and kidney function in resuscitated murine septic shock.

PURPOSE: Adrenomedullin (ADM) has been referred to as a double-edged sword during septic shock: On one hand, ADM supplementation improved organ perfusion and function, attenuated systemic inflammation, and ultimately reduced tissue apoptosis and mortality. On the other hand, ADM overproduction can cause circulatory collapse and organ failure due to impaired vasoconstrictor response and reduced myocardial contractility. Since most of these data originate from un-resuscitated shock models, we tested the hypothesis whether the newly developed anti-ADM antibody HAM1101 may improve catecholamine responsiveness and thus attenuate organ dysfunction during resuscitated murine, cecal ligation and puncture (CLP)-induced septic shock. METHODS: Immediately after CLP, mice randomly received vehicle (phosphate-buffered saline, n = 11) or HAM1101 (n = 9; 2 µg·g(-1)). Fifteen hours after CLP, animals were anesthetized, mechanically ventilated, instrumented, and resuscitated with hydroxyethylstarch and continuous i.v. norepinephrine to achieve normotensive hemodynamics (mean arterial pressure > 50 to 60 mmHg). RESULTS: HAM1101 pretreatment reduced the norepinephrine infusion rates required to achieve hemodynamic targets, increased urine flow, improved creatinine clearance, and lowered neutrophil gelatinase-associated lipocalin blood levels, which coincided with reduced expression of the inducible nitric oxide synthase and formation of peroxynitrite (nitrotyrosine immunostaining) in the kidney and aorta, ultimately resulting in attenuated systemic inflammation and tissue apoptosis. CONCLUSIONS: During resuscitated murine septic shock, early ADM binding with HAM1101 improved catecholamine responsiveness, blunted the shock-related impairment of energy metabolism, reduced nitrosative stress, and attenuated systemic inflammatory response, which was ultimately associated with reduced kidney dysfunction and organ injury.

Effects of the PPAR-ß/δ agonist GW0742 during resuscitated porcine septic shock.

BACKGROUND: In un-resuscitated rodent models of septic shock, the peroxisome proliferator-activated receptor-ß/δ (PPAR-ß/δ) agonist GW0742 improved visceral organ function. Therefore, we tested the hypothesis whether GW0742 would attenuate kidney injury during long-term, resuscitated, porcine polymicrobial septic shock. METHODS: Six, 12, and 18 h after the induction of fecal peritonitis by inoculation of autologous feces, anesthetized, mechanically ventilated, and instrumented male pigs with pre-existing atherosclerosis resulting from familial hypercholesteremia and atherogenic diet randomly received either vehicle (dimethyl sulfoxide, n = 12) or GW0742 (n = 10). Resuscitation comprised hydroxyethyl starch and norepinephrine infusion titrated to maintain mean arterial pressure at baseline values. RESULTS: Despite aggressive fluid resuscitation, fecal peritonitis was associated with arterial hypotension requiring norepinephrine infusion, ultimately resulting in progressive lactic acidosis and acute kidney injury. GW0742 did not beneficially affect any parameter of systemic and regional hemodynamics, gas exchange, metabolism, or organ function. The parameters of inflammation, oxidative and nitrosative stress, and organ injury (post-mortem analysis for histomorphology and markers of apoptosis) were not influenced either. Immunohistochemistry of pre-shock kidney biopsies from a previous study in this swine strain showed markedly lower PPAR-ß/δ receptor expression than in healthy animals. CONCLUSIONS: In swine with pre-existing atherosclerosis, the PPAR-ß/δ agonist GW0742 failed to attenuate septic shock-induced circulatory failure and kidney dysfunction, most likely due to reduced receptor expression coinciding with cardiovascular and metabolic co-morbidity.

Effects of intravenous sulfide during resuscitated porcine hemorrhagic shock*.

OBJECTIVE: Controversial data are available on the effects of hydrogen sulfide during hemorrhage. Because the clinical significance of hydrogen sulfide administration in rodents may not be applicable to larger species, we tested the hypothesis whether intravenous Na2S (sulfide) would beneficially influence organ dysfunction during long-term, porcine hemorrhage and resuscitation. DESIGN: Prospective, controlled, randomized study. SETTING: University animal research laboratory. SUBJECTS: Forty-five domestic pigs of either gender. INTERVENTIONS: Anesthetized and instrumented animals underwent 4 hrs of hemorrhage (removal of 40% of the blood volume and subsequent blood removal/retransfusion to maintain mean arterial pressure at 30 mm Hg). Sulfide infusion was started 2 hrs before hemorrhage, simultaneously with blood removal or at the beginning of retransfusion of shed blood, and continued for 12 hrs. Resuscitation comprised hydroxyethyl starch and norepinenephrine infusion titrated to maintain mean arterial pressure at preshock values. MEASUREMENTS AND MAIN RESULTS: Before, immediately at the end of and 12 and 22 hrs after hemorrhage, we measured systemic and regional hemodynamics (portal vein, hepatic and right kidney artery ultrasound flow probes) and oxygen transport, nitric oxide and cytokine production (nitrate+nitrite, interleukin-6, tumor necrosis factor-α levels). Postmortem biopsies were analyzed for histomorphology (hematoxylin and eosin staining) and DNA damage (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling staining). The progressive kidney (creatinine levels, creatinine clearance), liver (transaminase activities, bilirubin levels), and cardiocirculatory (norepipnehrine requirements, troponin I levels) dysfunction was attenuated in the simultaneous treatment group only, which coincided with reduced lung, liver, and kidney histological damage. Sulfide reduced mortality, however, irrespective of the timing of its administration. CONCLUSIONS: While the sulfide-induced protection against organ injury was only present when initiated simultaneously with blood removal, it was largely unrelated to hypothermia. The absence of sulfide-mediated protection in the pretreatment protocol may be due to the accumulation of sulfide during low flow states. In conclusion, sulfide treatment can be effective in hemorrhagic shock, but its effectiveness is restricted to a narrow timing and dosing window.

Toward the quantification of the 13CO2/12CO2 ratio in exhaled mouse breath with mid-infrared hollow waveguide gas sensors.

Mouse sepsis models are used to gain insight into the complex processes involved with patients suffering from glucose metabolism disorders. Measuring the expiratory release of (13)CO(2) after administering stable labeled (13)C(6)-glucose enables assessment of the in vivo integrity and functionality of key metabolic processes. In the present study, we demonstrate that Fourier transform infrared spectroscopy operating in the mid-infrared spectral regime (2-20 µm) combined with hollow waveguide gas sensing modules simultaneously serving as a miniaturized gas cell and as a waveguide are capable of quantitatively monitoring (13)CO(2) enrichment levels in low volume mouse breath samples.

13CO2 breath tests, a tool to assess intestinal and liver function in the ICU?

PURPOSE OF REVIEW: CO2 breath tests, based on nondispersive infrared (NDIR) measurement technology, offer the chance for a noninvasive online quantitation of physiological processes. With recent extensions of the NDIR measurement technology breath tests could be used in an ICU setting without any restriction. Since online tools to assess feed intolerance with gastric emptying and to quantify gradual changes in liver function are still missing, this review explores the potential of breath tests to fill this gap. RECENT FINDINGS: Gastric emptying may be correctly quantified; however, the corresponding tests fail to capture aberrations in nutrient absorption, which appear to be linked to hyperglycemia and insulin resistance and may contribute to feed intolerance. The progression or ameloriation of liver injury could be assessed with breath tests, which cannot, however, distinguish between functional and macrocirculatory or microcirculatory disorders. SUMMARY: Breath tests for liver function and gastric emptying taken alone may fail in their ability to specifically quantify the clinical disorders. However, invasive test extensions could help to characterize their validity and thus to identify additional, noninvasive measurements to assure and expand this domain.

Cardiac and metabolic effects of hypothermia and inhaled hydrogen sulfide in anesthetized and ventilated mice.

OBJECTIVE: To test the hypothesis whether inhaled hydrogen sulfide amplifies the effects of deliberate hypothermia during anesthesia and mechanical ventilation as hypothermia is used to provide organ protection after brain trauma or circulatory arrest. Awake mice inhaling hydrogen sulfide exhibit reduced energy expenditure, hypothermia, and bradycardia despite unchanged systolic heart function. In rodents, anesthesia alone causes decreased metabolic rate and thus hypothermia and bradycardia. DESIGN: Prospective, controlled, randomized study. SETTING: University animal research laboratory. SUBJECTS: Male C57/B6 mice. INTERVENTIONS: After surgical instrumentation (central venous, left ventricular pressure-conductance catheters, ultrasound flow probes on the portal vein and superior mesenteric artery), normo- or hypothermic animals (core temperature = 38 degrees C and 27 degrees C) received either 100 ppm hydrogen sulfide or vehicle over 5 hrs (3 hrs hydrogen sulfide during normothermia). MEASUREMENTS AND MAIN RESULTS: During normothermia, hydrogen sulfide had no hemodynamic or metabolic effect. With or without hydrogen sulfide, hypothermia decreased blood pressure, heart rate, and cardiac output, whereas stroke volume, ejection fraction, and end-diastolic pressure remained unaffected. Myocardial and hepatic oxidative deoxyribonucleic acid damage (comet assay) and endogenous glucose production (rate of appearance of 1,2,3,4,5,6-13C6-glucose) were similar in all groups. Hypothermia comparably decreased CO2 production with or without inhaled hydrogen sulfide. During hypothermia, inhaled hydrogen sulfide increased the glucose oxidation rate (derived from the expiratory 13CO2/12CO2 ratio). This shift toward preferential carbohydrate utilization coincided with a significantly attenuated responsiveness of hepatic mitochondrial respiration to stimulation with exogenous cytochrome-c-oxidase (high-resolution respirometry). CONCLUSIONS: In anesthetized and mechanically ventilated mice, inhaled hydrogen sulfide did not amplify the systemic hemodynamic and cardiac effects of hypothermia alone. The increased aerobic glucose oxidation together with the reduced responsiveness of cellular respiration to exogenous cytochrome-c stimulation suggest that, during hypothermia, inhaled hydrogen sulfide improved the yield of mitochondrial respiration, possibly via the maintenance of mitochondrial integrity. Hence, inhaled hydrogen sulfide may offer metabolic benefit during therapeutic hypothermia.

Comparison of cardiac, hepatic, and renal effects of arginine vasopressin and noradrenaline during porcine fecal peritonitis: a randomized controlled trial.

INTRODUCTION: Infusing arginine vasopressin (AVP) in vasodilatory shock usually decreases cardiac output and thus systemic oxygen transport. It is still a matter of debate whether this vasoconstriction impedes visceral organ blood flow and thereby causes organ dysfunction and injury. Therefore, we tested the hypothesis whether low-dose AVP is safe with respect to liver, kidney, and heart function and organ injury during resuscitated septic shock. METHODS: After intraperitoneal inoculation of autologous feces, 24 anesthetized, mechanically ventilated, and instrumented pigs were randomly assigned to noradrenaline alone (increments of 0.05 microg/kg/min until maximal heart rate of 160 beats/min; n = 12) or AVP (1 to 5 ng/kg/min; supplemented by noradrenaline if the maximal AVP dosage failed to maintain mean blood pressure; n = 12) to treat sepsis-associated hypotension. Parameters of systemic and regional hemodynamics (ultrasound flow probes on the portal vein and hepatic artery), oxygen transport, metabolism (endogenous glucose production and whole body glucose oxidation derived from blood glucose isotope and expiratory 13CO2/12CO2 enrichment during 1,2,3,4,5,6-13C6-glucose infusion), visceral organ function (blood transaminase activities, bilirubin and creatinine concentrations, creatinine clearance, fractional Na+ excretion), nitric oxide (exhaled NO and blood nitrate + nitrite levels) and cytokine production (interleukin-6 and tumor necrosis factor-alpha blood levels), and myocardial function (left ventricular dp/dtmax and dp/dtmin) and injury (troponin I blood levels) were measured before and 12, 18, and 24 hours after peritonitis induction. Immediate post mortem liver and kidney biopsies were analysed for histomorphology (hematoxylin eosin staining) and apoptosis (TUNEL staining). RESULTS: AVP decreased heart rate and cardiac output without otherwise affecting heart function and significantly decreased troponin I blood levels. AVP increased the rate of direct, aerobic glucose oxidation and reduced hyperlactatemia, which coincided with less severe kidney dysfunction and liver injury, attenuated systemic inflammation, and decreased kidney tubular apoptosis. CONCLUSIONS: During well-resuscitated septic shock low-dose AVP appears to be safe with respect to myocardial function and heart injury and reduces kidney and liver damage. It remains to be elucidated whether this is due to the treatment per se and/or to the decreased exogenous catecholamine requirements.

Hemodynamic, metabolic, and organ function effects of pure oxygen ventilation during established fecal peritonitis-induced septic shock.

OBJECTIVE: To test the hypothesis whether pure oxygen ventilation is equally safe and beneficial in fully developed fecal peritonitis-induced septic shock as hyperoxia initiated at the induction of sepsis. DESIGN: Prospective, randomized, controlled, experimental study with repeated measures. SETTING: Animal research laboratory at a university medical school. SUBJECTS: Twenty anesthetized, mechanically ventilated, and instrumented pigs. INTERVENTIONS: Twelve hours after induction of fecal peritonitis by inoculation of autologous feces, swine, which were resuscitated with hydroxyethyl starch and norepinephrine to maintain mean arterial pressure at baseline values, were ventilated randomly with an Fio2 required to keep Sao2 >90% (controls: n = 10) or Fio2 1.0 (hyperoxia, n = 10) during the next 12 hrs. MEASUREMENTS AND MAIN RESULTS: Despite similar hemodynamic support (hydroxyethyl starch and norepinephrine doses), systemic and regional macrocirculatory and oxygen transport parameters, hyperoxia attenuated pulmonary hypertension, improved gut microcirculation (ileal mucosal laser Doppler flowmetry) and portal venous acidosis, prevented the deterioration in creatinine clearance (controls 61 (44;112), hyperoxia: 96 (88;110) mL.min(-1), p = .074), and attenuated the increase in blood tumor necrosis factor-alpha concentrations (p = .045 and p = .112 vs. controls at 18 hrs and 24 hrs, respectively). Lung and liver histology (hematoxyline eosine staining) were comparable in the two groups, but hyperoxia reduced apoptosis (Tunel test) in the liver (4 (3;8) vs. 2 (1;5) apoptotic cells/field, p = .069) and the lung (36 (31;46) vs. 15 (13;17) apoptotic cells/field, p < .001). Parameters of lung function, tissue antioxidant activity, blood oxidative and nitrosative stress (nitrate + nitrite, 8-isoprostane levels; deoxyribonucleic acid (DNA) damage measured using the comet assay) were not further affected during hyperoxia. CONCLUSIONS: When compared with the previous report on hyperoxia initiated simultaneously with induction of sepsis, i.e., using a pretreatment approach, pure oxygen ventilation started when porcine fecal peritonitis-induced septic shock was fully developed proved to be equally safe with respect to lung function and oxidative stress, but exerted only moderate beneficial effects.