Oscar McCook

Universität Ulm, Ulm, Baden-Württemberg, Germany

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Publications (25)78.34 Total impact

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    ABSTRACT: Our aim was to study the ability of an immortalized cell line (AMJ2-C11) to sustain aerobic cell respiration at decreasing oxygen concentrations under continuous sulfide exposure. We assumed that the rate of elimination of sulfide through the pathway linked to the mitochondrial respiratory chain and therefore operating under aerobic conditions, should decrease with limiting oxygen concentrations. Thus, sulfide's inhibition of cellular respiration would occur faster under continuous sulfide exposure when the oxygen concentration is in the very low range. The experiments were performed with an O2K-oxygraph (Oroboros Instruments) by suspending 0.5 - 1 x 10(6) cells in 2 ml of continuously stirred respiration medium at 37°C and calculating the oxygen flux (JO2) as the negative derivative of the oxygen concentration in the medium. The cells were studied in two different metabolic states, namely under normal physiologic respiration (1) and after uncoupling of mitochondrial respiration (2). Oxygen concentration was controlled by means of a titration-injection pump, resulting in average concentration values of 0.73 ± 0.05 μM, 3.1 ± 0.2 μM, and 6.2 ± 0.2 μM. Simultaneously we injected a 2 mM Na2S solution at a continuous rate of 10 μl/s in order to quantify the titration-time required to reduce the JO2 to 50% of the initial respiratory activity. Under the lowest oxygen concentration this effect was achieved after 3.5 [0.3;3.5] and 11.7 [6.2;21.2] min in the uncoupled and coupled state, respectively. This time was statistically significantly shorter when compared to the intermediate and the highest O2 concentrations tested, which yielded values of 24.6[15.5;28.1] min (coupled) and 35.9[27.4;59.2] min (uncoupled), as well as 42.4 [27.5;42.4] min (coupled) and 51.5 [46.4;51.7] min (uncoupled). All data are medians [25%, and 75% percentiles]. Our results confirm that the onset of inhibition of cell respiration by sulfide occurs earlier under a continuous exposure when approaching the anoxic condition. This property may contribute to the physiological role of sulfide as an oxygen sensor.
    Nitric oxide : biology and chemistry / official journal of the Nitric Oxide Society. 06/2014;
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    ABSTRACT: Numerous papers have been published on the role of H2S during circulatory shock. Consequently, knowledge about vascular sulfide concentrations may assume major importance, in particular in the context of “acute on chronic disease”, i.e., during circulatory shock in animals with pre-existing chronic disease. This review addresses the questions i) of the “real” sulfide levels during circulatory shock, and, ii) to which extent injury and pre-existing co-morbidity may affect the expression of H2S producing enzymes under these conditions. In the literature there is a huge range on sulfide blood levels during circulatory shock, in part as a result of the different analytical methods used, but also due to the variable of the models and species studied. Clearly, some of the very high levels reported should be questioned in the context of the well-known H2S toxicity. As long as “real” sulfide levels during circulatory shock are unknown and/or undetectable “on line” due to the lack of appropriate techniques, it appears to be premature to correlate the measured blood levels of hydrogen sulfide with the severity of shock or the H2S therapy-related biological outcomes. The available data on the tissue expression of the H2S-releasing enzymes during circulatory shock suggest that a “constitutive” CSE expression may play a crucial role of for the maintenance of organ function, at least in the kidney. The data also indicate that increased CBS and CSE expression, in particular in the lung and the liver, represents an adaptive response to stress states.
    Nitric Oxide 01/2014; · 3.27 Impact Factor
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    ABSTRACT: Our aim was to study the ability of an immortalized cell line (AMJ2-C11) to sustain aerobic cell respiration at decreasing oxygen concentrations under continuous sulfide exposure. We assumed that the rate of elimination of sulfide through the pathway linked to the mitochondrial respiratory chain and therefore operating under aerobic conditions, should decrease with limiting oxygen concentrations. Thus, sulfide’s inhibition of cellular respiration would occur faster under continuous sulfide exposure when the oxygen concentration is in the very low range. The experiments were performed with an O2K-oxygraph (Oroboros Instruments) by suspending 0.5–1 × 106 cells in 2 ml of continuously stirred respiration medium at 37 °C and calculating the oxygen flux (JO2) as the negative derivative of the oxygen concentration in the medium. The cells were studied in two different metabolic states, namely under normal physiologic respiration (1) and after uncoupling of mitochondrial respiration (2). Oxygen concentration was controlled by means of a titration-injection pump, resulting in average concentration values of 0.73 ± 0.05 μM, 3.1 ± 0.2 μM, and 6.2 ± 0.2 μM. Simultaneously we injected a 2 mM Na2S solution at a continuous rate of 10 μl/s in order to quantify the titration-time required to reduce the JO2 to 50% of the initial respiratory activity. Under the lowest oxygen concentration this effect was achieved after 3.5 [0.3;3.5] and 11.7 [6.2;21.2] min in the uncoupled and coupled state, respectively. This time was statistically significantly shorter when compared to the intermediate and the highest O2 concentrations tested, which yielded values of 24.6 [15.5;28.1] min (coupled) and 35.9 [27.4;59.2] min (uncoupled), as well as 42.4 [27.5;42.4] min (coupled) and 51.5 [46.4;51.7] min (uncoupled). All data are medians [25%, and 75% percentiles]. Our results confirm that the onset of inhibition of cell respiration by sulfide occurs earlier under a continuous exposure when approaching the anoxic condition. This property may contribute to the physiological role of sulfide as an oxygen sensor.
    Nitric Oxide. 01/2014;
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    Intensive Care Medicine Experimental. 10/2013; 1:2.
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    ABSTRACT: Background: In un-resuscitated rodent models of septic shock, the peroxisome proliferator-activated receptor-beta/delta (PPAR-beta/delta) 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 18h 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-beta/delta receptor expression than in healthy animals. Conclusions: In swine with pre-existing atherosclerosis, the PPAR-beta/delta 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.
    Intensive Care Med Exp. 10/2013; 1:9.
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    ABSTRACT: The reported sulfide absorption values and baseline blood concentrations are still controversial [1]. We modified an existing gas chromatographic/mass spectrometric method of routine sulfide quantification using a bis-pentafluorobenzyl derivative [2]. This approach allows sensitive determination of sulfide in small sample volumes under mild chemical conditions. In addition, in in vitro experiments, it allows to distinguish between endogenous and exogenous sulfide by administration of the stable isotope (34)S(2-). A standard protocol utilises 100μl of blood, but can be scaled down to 25μl for rodent samples . In brief, a mixture, consisting of 400μl internal standard (5μg/ml tribromobenzene in isooctane), 200μl of alkylation reagent (10μl/ml pentafluorobenzylbromide in isooctane) and 400μl of phase transfer catalyst (2mg/ml tetradecyldimethylbenzylammonium chloride in sodium tetraborate saturated water) was prepared. After addition of 100μl sample, the mixture was vigorously shaken for 1min, 400μl of saturated potassium dihydrogenphosphate solution were added and the cup was shaken for another 10s. 2μl of the isooctane phase were injected into an Agilent 5890/5970 gas chromatography/mass spectrometry instrument, housing a 12m Macherey-Nagel Optima-5MS capillary column. In sim mode ions m/z 313.7 for the internal standard and 394.0 for the sulfide derivative (or 396.0 for (34)S(2-)) were recorded. The method was used to determine basal sulfide blood concentrations in pigs and to measure the sulfide release from the sulfide releasing drug GYY4137 over 24h in cell culture medium. In addition this method reproducibly was used to determine the absorption of a spike of 100μM (34)S(2-) at pH 7.4 in buffer, blood, plasma, cysteine, glutathione and albumine. Baseline blood sulfide concentrations in pigs were between 0.2 and 2.1μM. Sulfide concentrations of a 300μM solution of GYY4137 in cell culture medium (in cell culture flask, gas exchange enabled) were 1.02μM (10min after GYY addition), 1.32μM (2h), 1.37μM (4h), 1.60μM (8h), 1.58μM (12h) and 1.81μM (24h). The sulfide concentration of the corresponding medium without GYY4137 ranged between 0.25 and 0.50μM. An initial 100μM spike of (34)S(2-) in blood decreased to 23μM after 1min, 12μM after 10 and 1μM after 60min. The corresponding values for plasma were 60, 41 and 3μM, for phosphate buffer (pH 7.4) 103, 96 and 85μM. In a 50mg/ml solution of albumine the (34)S(2-) concentration decreased to 22, 15, 3μM, in 5mg/ml oxidized glutathione to 32, 18, 3μM, in 5mg/ml reduced glutathione to 79, 76, 75μM, in 120μg/ml cystine to 91, 64, 12μM and in 1mg/ml cysteine to 110, 102, 99μM. Our findings show, that sulfide baseline concentrations in blood are in the low micromolar range. Added sulfide is rapidly absorbed by blood, plasma and disulfide bridge containing peptides and proteins, but much lower by the reduced species. Adding the sulfide releasing drug GYY4137, increased the sulfid concentration of cell culture media for 24h.
    Nitric oxide : biology and chemistry / official journal of the Nitric Oxide Society. 09/2013; 31 Suppl 2:S58-9.
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    ABSTRACT: The reported sulfide absorption values and baseline blood concentrations are still controversial [1]. We modified an existing gas chromatographic/mass spectrometric method of routine sulfide quantification using a bis-pentafluorobenzyl derivative [2]. This approach allows sensitive determination of sulfide in small sample volumes under mild chemical conditions. In addition, in in vitro experiments, it allows to distinguish between endogenous and exogenous sulfide by administration of the stable isotope (34)S(2-). A standard protocol utilises 100μl of blood, but can be scaled down to 25μl for rodent samples. In brief, a mixture, consisting of 400μl internal standard (5μg/ml tribromobenzene in isooctane), 200μl of alkylation reagent (10μl/ml pentafluorobenzylbromide in isooctane) and 400μl of phase transfer catalyst (2mg/ml tetradecyldimethylbenzylammonium chloride in sodium tetraborate saturated water) was prepared. After addition of 100μl sample, the mixture was vigorously shaken for 1min, 400μl of saturated potassium dihydrogenphosphate solution were added and the cup was shaken for another 10s. 2μl of the isooctane phase were injected into an Agilent 5890/5970 gas chromatography/mass spectrometry instrument, housing a 12m Macherey-Nagel Optima-5MS capillary column. In sim mode ions m/z 313.7 for the internal standard and 394.0 for the sulfide derivative (or 396.0 for (34)S(2-)) were recorded. The method was used to determine basal sulfide blood concentrations in pigs and to measure the sulfide release from the sulfide releasing drug GYY4137 over 24h in cell culture medium. In addition this method reproducibly was used to determine the absorption of a spike of 100μM (34)S(2-) at pH 7.4 in buffer, blood, plasma, cysteine, glutathione and albumine. Baseline blood sulfide concentrations in pigs were between 0.2 and 2.1μM. Sulfide concentrations of a 300μM solution of GYY4137 in cell culture medium (in cell culture flask, gas exchange enabled) were 1.02μM (10min after GYY addition), 1.32μM (2h), 1.37μM (4h), 1.60μM (8h), 1.58μM (12h) and 1.81μM (24h). The sulfide concentration of the corresponding medium without GYY4137 ranged between 0.25 and 0.50μM. An initial 100μM spike of (34)S(2-) in blood decreased to 23μM after 1min, 12μM after 10 and 1μM after 60min. The corresponding values for plasma were 60, 41 and 3μM, for phosphate buffer (pH 7.4) 103, 96 and 85μM. In a 50mg/ml solution of albumine the (34)S(2-)concentration decreased to 22, 15, 3μM, in 5mg/ml oxidized glutathione to 32, 18, 3μM, in 5mg/ml reduced glutathione to 79, 76, 75μM, in 120μg/ml cystine to 91, 64, 12μM and in 1mg/ml cysteine to 110, 102, 99μM. Our findings show, that sulfide baseline concentrations in blood are in the low micromolar range. Added sulfide is rapidly absorbed by blood, plasma and disulfide bridge containing peptides and proteins, but much lower by the reduced species. Adding the sulfide releasing drug GYY4137, increased the sulfide concentration of cell culture media for 24h.
    Nitric oxide : biology and chemistry / official journal of the Nitric Oxide Society. 09/2013; 31 Suppl 2:S20.
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    ABSTRACT: H2S production in the kidney, both before and after ischemic injury, and its regulation via endogenous synthesizing enzymes: cystathionine β synthase (CBS), γ lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (MST) remains controversial. The conflicting results were all reported in non-resuscitated young and healthy rodent models that have come into question with regard to their applicability to humans, let alone the co-morbidity frequently present in ICU patients. To understand the endogenous H2S synthesis in disease states, we compared kidneys from swine strains with and without pre-existing cardiovascular co-morbidity. CSE, CBS and MST expression was quantified by immunohistochemistry (densitometric image analysis, presented as mean sum of densitometric units x10(5)) of formalin-fixed paraffin sections from both pre-injury and post-ischemia/reperfusion (I/R) kidney biopsies taken in young and healthy pigs (German Landrace, n=8 ) as well as swine strain with familial hypercholesterolemia (FBM, n=8) (11.1 (7.4;12.3) vs. 1.4 (1.3;1.5) mmol/L, p<0.01, n=20 and 15, resp.) and consecutive, diet-induced atherosclerosis. Arterial blood 8-isoprostane (commercially available ELISA kit) and nitrite+nitrate (chemiluminescence) concentrations were measured as markers of lipid peroxidation and NO production. Urine was sampled during 2 hours before aortic occlusion and 8 hours of reperfusion. Urinary and blood creatinine and Na(+) levels allowed calculating creatinine clearance (glomerular filtration) and fractional Na(+) excretion (tubular re-absorption). Atherosclerotic swine presented with reduced glomerular filtration (creatinine clearance 76 (60;83) vs. 103 (79;120) mL/min, n=19 each, p<0.004) and chronic histological kidney injury (dilatation of Bowman's space, swelling of Bowman's capsule, tubular dilatation). Baseline isoprostane levels were higher than in the healthy German Landrace swine (111±47 vs. 74±16pg/mL, p<0.005), while endogenous NO production rate was lower as indicated by the lower nitrate+nitrite levels (baseline levels 140±360 vs. 770±800μmol/L, p<0.001). There was no difference in the CSE expression of native kidneys specimens (1520 (1430;1570) vs. 1590 (1430;1590) AU). Kidney I/R injury was associated with down-regulation of CSE expression, which was significantly more pronounced in the FBM swine (400 (280;460) AU, p=0.003 vs. before I/R injury; young and healthy German landrace swine 1110 (1020;1210) AU, p=0.028 vs. before I/R injury; p=0.001 between groups). CBS expression was not present in native biopsies, and minimal only post I/R, i.e. in necrotic tubules and cells only. FBM swine presented with higher MST expression prior to I/R injury (p=0.030 vs. healthy German Landrace swine). I/R injury increased MST expression (FBM swine 476 (200;770) vs. 91 (30;150) AU; young and healthy German Landrace swine (156 (138;231) vs. 0.06 (0.001;1) AU; both p=0.004 vs. before I/R), the difference between FBM and healthy domestic swine being less pronounced than prior to kidney I/R (p=0.002 between groups). I/R injury caused a down-regulation of the CSE enzyme in young and healthy swine. This response was significantly more pronounced in swine with underlying atherosclerotic disease, possibly due to systemically reduced NO and increased reactive oxygen species formation. MST up-regulation coincides with increased kidney injury and may be playing a detoxifying role.
    Nitric oxide : biology and chemistry / official journal of the Nitric Oxide Society. 09/2013; 31 Suppl 2:S48-9.
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    ABSTRACT: Disturbed endogenous H2S production as a result down-regulation of the H2S-catalyzing enzymes cysthathionine-γ-lyase (CSE) and cysthathione-β-synthase (CBS) is associated with chronic cardiovascular pathology, e.g. hypertension, atherosclerosis, and chronic kidney disease [1-3]. CSE and CBS up-regulation was found during acute hyperinflammatory states resulting from circulatory shock [4-11], but little is known on the effect of acute stress states on CSE and CBS expression during chronic disease. Therefore we measured CBS and CSE expression before and after porcine kidney ischemia/reperfusion (I/R) injury comparing otherwise healthy animals and swine with ubiquitous atherosclerosis resulting from a mutation of the LDL receptor together with a cholesterol-enriched diet [12,13]. CBS expression was not present in native biopsies, and minimal only post I/R, i.e. in necrotic tubules and cells only. Atherosclerotic swine had lower CSE expression in native biopsies. I/R injury caused a down-regulation of the CSE enzyme in both groups, which was more pronounced in the atherosclerotic animals. In the atherosclerotic swine fecal peritonitis-induced septic shock also caused marked down-regulation of kidney CSE expression when compared to sham-operated animals. Therefore, the effect of H2S-supplementation using the slow-releasing H2S donor GYY4137 [14] in atherosclerotic swine with septic shock will be shown. GYY4137 is used to avoid the short and high and therefore potentially deleterious peak sulfide concentrations associated with NaSH or Na2S administration. Equivocal data are available on H2S-catalyzing enzymes during cigarette smoke-induced lung disease: both reduced [15,16] and increased [16,17] CSE expression were reported. So far, no data are available whether chronic lung disease affects the otherwise pronounced increase in CSE and CBS expression after trauma [18] or sepsis [4-7,10,11]. Therefore, the effects of genetic CSE deletion and H2S-supplementation using the slow-releasing H2S donor GYY4137 in mice with cigarette smoke-induced COPD undergoing pressure wave-generated blunt chest trauma [18] will be shown.
    Nitric oxide : biology and chemistry / official journal of the Nitric Oxide Society. 09/2013; 31 Suppl 2:S12-3.
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    ABSTRACT: 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.
    Critical care medicine 03/2013; · 6.37 Impact Factor
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    ABSTRACT: PURPOSE: To test the hypothesis that a carbamylated EPO-FC fusion protein (cEPO-FC) or recombinant human erythropoietin (rhEPO) would protect against kidney ischemia/reperfusion (I/R) injury in pigs with atherosclerosis. METHODS: Anesthetized and mechanically ventilated animals received cEPO-FC (50 μg kg(-1)), rhEPO (5,000 IU kg(-1)), or vehicle (n = 9 per group) prior to 120 min of aortic occlusion and over 4 h of reperfusion. During aortic occlusion, mean arterial pressure (MAP) was maintained at 80-120 % of baseline values by esmolol, nitroglycerin, and ATP. During reperfusion, noradrenaline was titrated to keep MAP at pre-ischemic levels. Blood creatinine and neutrophil gelatinase-associated lipocalin (NGAL) levels, creatinine clearance, fractional Na(+) excretion, and HE and PAS staining were used to assess kidney function and histological damage. Plasma interleukin-6, tumor necrosis factor-α, nitrate + nitrite and 8-isoprostane levels were measured to assess systemic inflammation, and nitrosative and oxidative stress. RESULTS: I/R caused acute kidney injury with reduced creatinine clearance, increased fractional Na(+) excretion and NGAL levels, moderate to severe glomerular and tubular damage and apoptosis, systemic inflammation and oxidative and nitrosative stress, but there were no differences between the treatment groups. Pre-ischemia nitrate + nitrite and 8-isoprostanes levels were lower and higher, respectively, than in healthy animals of a previous study, and immune histochemistry showed higher endothelial nitric oxide synthase and lower EPO receptor expression in pre-ischemia kidney biopsies than in biopsies from healthy animals. CONCLUSIONS: In swine with atherosclerosis, rhEPO and cEPO-FC failed to attenuate prolonged ischemia-induced kidney injury within an 8-h reperfusion period, possibly due to reduced EPO receptor expression resulting from pre-existing oxidative stress and/or reduced NO release.
    European Journal of Intensive Care Medicine 01/2013; · 5.17 Impact Factor
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    ABSTRACT: There is a plethora of experimental data on the potential therapeutic benefits of recombinant human erythropoietin (rhEPO) and its synthetic derivatives in critical care medicine, in particular in ischemia/reperfusion injury. Most of the recent clinical trials have not shown clear benefits, and, in some patients, EPO-aggravated morbidity and mortality was even reported. Treatment with rhEPO has been successfully used in patients with anemia resulting from chronic kidney disease, but even a subset of this patient population does not adequately respond to rhEPO therapy. The following viewpoint uses rhEPO as an example to highlight the possible pitfalls in current practice using young healthy animals for the evaluation of therapies to treat patients of variable age and underlying chronic co-morbidity.
    Critical care (London, England) 09/2012; 16(5):319. · 4.72 Impact Factor
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    ABSTRACT: Previous studies suggest that sulfide-induced inhibition of cytochrome c oxidase (cCox) and, consequently, the metabolic and toxic effects of sulfide are less pronounced at low body temperature. Because the temperature-dependent effects of sulfide on the inflammatory response are still a matter of debate, we investigated the impact of varying temperature on the cCox excess capacity and the mitochondrial sulfide oxidation by the sulfide-ubiquinone oxidoreductase in macrophage-derived cell lines (AMJ2-C11 and RAW 264.7). Using an oxygraph chamber, the inhibition of mitochondrial respiration was measured by stepwise titrations with sulfide and the nonmetabolizable cCox inhibitor sodium azide at 25°C and 37°C. Using the latter of the two inhibitors, the excess capacity of the cCox was obtained. Furthermore, we quantified the capacity of these cells to withstand sulfide inhibition by measuring the amount required to inhibit respiration by 50% and 90% and the viability of the cells after 24-h exposure to 100 ppm of hydrogen sulfide. At low titration rates, the AMJ2-C11 cells, but not the RAW 264.7 cells, increased their capacity to withstand exogenously added sulfide. This effect was even greater at 25°C than at 37°C. Furthermore, only the AMJ2-C11 cells remained viable after sulfide exposure for 24 h. In contrast, only in the RAW 264.7 cells that an increase in cCox excess capacity was found at low temperatures. In macrophage-derived cell lines, both the excess capacity of cCox and the efficiency of sulfide elimination may increase at low temperatures. These properties may modify the effects of sulfide in immune cells and, potentially, the inflammatory response during sulfide exposure at different body temperatures.
    Shock (Augusta, Ga.) 07/2012; 38(4):367-74. · 2.87 Impact Factor
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    ABSTRACT: 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. Prospective, controlled, randomized study. University animal research laboratory. Forty-five domestic pigs of either gender. 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. 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. 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.
    Critical care medicine 07/2012; 40(7):2157-67. · 6.37 Impact Factor
  • Critical Care 03/2012; 16(1). · 4.93 Impact Factor
  • Critical Care 03/2012; 16(1). · 4.93 Impact Factor
  • Critical Care 03/2012; 16(1). · 4.93 Impact Factor
  • Critical Care 03/2012; 16(1). · 4.93 Impact Factor
  • Critical Care 03/2012; 16(1). · 4.93 Impact Factor
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    ABSTRACT: Recombinant human erythropoietin (rhEPO) attenuated ischemia/reperfusion (I/R) injury-induced spinal cord damage. Since carbamylated EPO derivatives are stated to be devoid of rhEPO side effects, we tested the hypothesis that a newly developed carbamylated EPO-FC fusion protein (cEPO-FC) would compare favorably with rhEPO. Anesthetized and mechanically ventilated pigs randomly received cEPO-FC (50 μg kg(-1)), rhEPO (5,000 IU kg(-1)) or vehicle (n = 9 per group) 30 min prior to 30 min of aortic occlusion and over the 4 h of reperfusion. During aortic occlusion, mean arterial pressure (MAP) was maintained at 80-120% of baseline values by esmolol, nitroglycerin, and adenosine-5'-triphosphate (ATP). During reperfusion, noradrenaline was titrated to keep MAP at pre-ischemic levels. Spinal cord function was assessed by motor evoked potentials (MEP) and lower limb reflexes. Tissue damage was evaluated using hematoxylin and eosin, Nissl, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. Plasma levels of interleukin-6, tumor necrosis factor-α, and 8-isoprostanes were measured as markers of systemic inflammation and oxidative stress. While only cEPO-FC restored MEP amplitude to values close to pre-occlusion levels, both cEPO-FC and rhEPO comparably restored lower limb reflexes and reduced the percentage of damaged neurons. Infiltration of mononuclear inflammatory cells was moderate without intergroup difference; positive TUNEL staining was barely detectable in any group. I/R injury increased blood cytokine levels without intergroup difference, whereas both cEPO-FC and rhEPO significantly lowered 8-isoprostane levels. In a porcine model of aortic balloon occlusion-induced spinal cord I/R injury, cEPO-FC and rhEPO comparably protected against ischemic spinal cord dysfunction and neuronal damage. This effect coincided with attenuated oxidative stress.
    European Journal of Intensive Care Medicine 09/2011; 37(9):1525-33. · 5.17 Impact Factor