Measures of injury severity and prediction of acute traumatic brain injury outcomes.

OBJECTIVE: To examine the comparative efficacy of 3 common measures of traumatic brain injury (TBI) severity for predicting inpatient outcomes upon hospital discharge. SETTING: Acute brain injury rehabilitation unit at level 1 trauma center. PARTICIPANTS: 100 patients with TBI. DESIGN: Retrospective analysis of injury severity, demographic, and outcome data. MAIN MEASURES: Glasgow Coma Scale (GCS) at admission, time to follow commands (TTC), duration of posttraumatic amnesia (PTA), and Functional Independence Measure at hospital discharge. RESULTS: A hierarchal multiple regression revealed that duration of PTA was a significant and powerful unique predictor of Functional Independence Measure scores at discharge (ß = -0.46, P = .001), while TTC (ß = 0.26, P = .056) and GCS (ß = 0.16, P = .143) were not. These effects were present even after controlling for age, gender, educational level, racial/ethnic minority status, cause of injury, history of substance abuse, and neurosurgical intervention. CONCLUSION: Although clinicians often use GCS scores and TTC when assessing acute TBI severity and during treatment formulation, this study provides evidence that duration of PTA may be a more meaningful predictor of patients' functional levels at discharge.

A soluble guanylate cyclase stimulator, BAY 41-8543, preserves right ventricular function in experimental pulmonary embolism.

Pulmonary embolism (PE) increases pulmonary vascular resistance, causing right ventricular (RV) dysfunction, and poor clinical outcome. Present studies test if the soluble guanylate cyclase stimulator BAY 41-8543 reduces pulmonary vascular resistance and protects RV function. Experimental PE was induced in anesthetized, male Sprague-Dawley rats by infusing 25 µm polystyrene microspheres (1.95 million/100 g body wt, right jugular vein) producing moderate PE. Pulmonary artery vascular resistance, estimated as RVPSP/CO, increased 3-fold after 5 h of PE. Treatment with BAY 41-8543 (50 µg/kg, I.V.; given at the time of PE induction) normalized this index by reducing RVPSP and markedly increasing CO, via preservation of heart rate and stroke volume. Ex vivo RV heart function showed minimal changes at 5 h of PE, but decreased significantly after 18 h of PE, including peak systolic pressure (PSP, Control 39 ± 1 mmHg vs. 19 ± 3 PE), +dP/dt (1192 ± 93 mmHg/s vs. 444 ± 64) and -dP/dt (-576 ± 60 mmHg/s vs. -278 ± 40). BAY 41-8543 significantly improved all three indices of RV heart function (PSP 35 ± 3.5, +dP/dt 1129 ± 100, -dP/dt -568 ± 87). Experimental PE produced increased PVR and RV dysfunction, which were ameliorated by treatment with BAY 41-8543. Thus, there is vasodilator reserve in this model of experimental PE that can be exploited to reduce the stress upon the heart and preserve RV contractile function.

Arginase depletes plasma l-arginine and decreases pulmonary vascular reserve during experimental pulmonary embolism.

The experiments test if experimental PE causes red blood cell hemolysis, arginase release and depletion of l-arginine and determine if arginase inhibition preserves l-arginine and improves pulmonary hemodynamics during PE. Experimental PE was induced in male Sprague-Dawley rats by infusing 25 µm microspheres (1.8 million/100 g body wt) in the jugular vein, producing moderate pulmonary hypertension. Pulmonary vascular resistance was estimated from the quotient of the right ventricular peak systolic pressure/cardiac output. Arterial plasma hemoglobin (ELISA), arginase activity (colorimetric assay) and l-arginine (high performance liquid chromatography) were determined. Arginase activity was inhibited by infusion of N-omega-hydroxy-nor-l-arginine (nor-NOHA, 400 mg/kg body wt, i.v.). Values are means ± s.e. Five hours of PE caused red blood cell hemolysis (15-fold increase in plasma hemoglobin) and release of arginase activity (2.7-fold increase). Plasma l-arginine concentration decreased significantly from 250 ± 20.6 to 118 ± 6.0 µmol/L (Control vs. PE) and estimated pulmonary vascular resistance increased 3-fold. Treatment with nor-NOHA prevented the depletion of plasma l-arginine (229 ± 15 µmol/L) and reduced the rise in pulmonary vascular resistance by 40%. In conclusion, experimental PE causes hemolysis, release of arginase activity, depletion of plasma l-arginine and increased estimated pulmonary vascular resistance. Inhibition of arginase activity preserves plasma l-arginine levels and improves estimated resistance, suggesting that the release of arginase during hemolysis contributes to the rise in estimated pulmonary resistance during experimental PE.

Pulmonary vascular reserve during experimental pulmonary embolism: effects of a soluble guanylate cyclase stimulator, BAY 41-8543.

OBJECTIVES: Pulmonary embolism causes pulmonary hypertension by mechanical obstruction and vasoconstriction. Therapeutic potential of pharmacologic dilation of unblocked vessels has received limited attention. We tested pulmonary vasodilator reserve using a soluble guanylate cyclase stimulator, BAY 41-8543. DESIGN: Controlled animal study. SETTING: Medical center research laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Pulmonary embolism was induced by infusing 25-µm plastic microspheres in the right jugular vein, producing mild or moderate pulmonary hypertension. Control animals with no pulmonary embolism received suspension medium for microspheres. MEASUREMENTS AND MAIN RESULTS: Mild pulmonary embolism increased right ventricular peak systolic pressure (from 28 to 38 mm Hg) and decreased cardiac output (from 46 to 34 mL/min) with no change in mean arterial pressure. Infusion of BAY 41-8543 (50-200 µg/kg) decreased right ventricular peak systolic pressure. Five hrs moderate pulmonary embolism increased right ventricular peak systolic pressure (from 28 to 47 mm Hg) and decreased cardiac output (from 48 to 27 mL/min), causing right ventricular peak systolic pressure/cardiac output to increase from 0.6 control with no pulmonary embolism to 1.8 mm Hg/mL/min in 5-hr moderate pulmonary embolism + solvent for BAY 41-8543. Treatment of 5-hr moderate pulmonary embolism with BAY 41-8543 (50 µg/kg) caused a 2.2-fold increase in cardiac output (59 mL/min) with a 46% reduction in right ventricular peak systolic pressure (38 mm Hg), suggesting significant pulmonary vasodilation. Moderate pulmonary embolism decreased arterial sO2 (from 83% to 71%) and increased lactate (from 0.5 to 2.3 mmol/L). Treatment with BAY 41-8543 normalized sO2 and lactate. Hemolysis occurred during moderate experimental pulmonary embolism (60-fold increase in plasma hemoglobin). Treatment with BAY 41-8543 reduced free plasma hemoglobin content by 80%. CONCLUSIONS: In the setting of moderate impervious pulmonary embolism, treatment with a guanylate cyclase stimulator normalized pulmonary hemodynamics, reduced hemolysis, and improved oxygenation. These data support the hypothesis that pharmacologic dilation of nonobstructed pulmonary vasculature can effectively treat acute pulmonary hypertension from pulmonary embolism.

Up-regulation of arginase II contributes to pulmonary vascular endothelial cell dysfunction during experimental pulmonary embolism.

Pulmonary embolism (PE) causes pulmonary hypertension by mechanical obstruction and constriction of non-obstructed vasculature. We tested if experimental PE impairs pulmonary vascular endothelium-dependent dilation via activation of arginase II. Experimental PE was induced in male Sprague-Dawley rats by infusing 25 µm microspheres in the right jugular vein, producing moderate pulmonary hypertension. Shams received vehicle injection. Pulmonary arterial rings were isolated after 18 h and isometric tensions were determined. Dilations were induced with acetylcholine, calcium ionophore A23187 or nitroglycerin (NTG) in pre-contracted rings (phenylephrine). Protein expression was assessed by Western blot and immunohistochemistry. Arginase activity was inhibited by intravenous infusion of N(w)-hydroxy-nor-l-arginine (nor-NOHA). l-Arginine supplementation was also given. Endothelium-dependent dilation responses were significantly reduced in PE vs. vehicle-treated animals (ACh: 50 ± 9% vs. 93 ± 3%; A23187: 19 ± 7% vs. 85 ± 7%, p < 0.05), while endothelium-independent dilations (NTG) were unchanged. Endothelial nitric oxide synthase (eNOS) protein content was unchanged by PE. Expression of arginase II increased 4.5-fold and immunohistochemistry revealed increased arginase II staining. Nor-NOHA treatment and l-arginine supplementation significantly improved pulmonary artery ring endothelium-dependent dilation in PE (ACh: 58 ± 6% PE, 88 ± 6% PE + nor-NOHA, 84 ± 4% PE + l-arginine). Experimental PE impairs endothelium-dependent pulmonary artery dilation, while endothelium-independent dilation remains unchanged. The data support the conclusion that up-regulation of arginase II protein expression contributes to pulmonary artery endothelial dysfunction in this model of experimental PE.

Right ventricular heart failure from pulmonary embolism: key distinctions from chronic pulmonary hypertension.

BACKGROUND: The right ventricle normally operates as a low pressure, high-flow pump connected to a high-capacitance pulmonary vascular circuit. Morbidity and mortality in humans with pulmonary hypertension (PH) from any cause is increased in the presence of right ventricular (RV) dysfunction, but the differences in pathology of RV dysfunction in chronic versus acute occlusive PH are not widely recognized. METHODS AND RESULTS: Chronic PH that develops over weeks to months leads to RV concentric hypertrophy without inflammation that may progress slowly to RV failure. In contrast, pulmonary embolism (PE) results in an abrupt vascular occlusion leading to increased pulmonary artery pressure within minutes to hours that causes immediate deformation of the RV. RV injury is secondary to mechanical stretch, shear force, and ischemia that together provoke a cytokine and chemokine-mediated inflammatory phenotype that amplifies injury. CONCLUSIONS: This review will briefly describe causes of pulmonary embolism and chronic PH, models of experimental study, and pulmonary vascular changes, and will focus on mechanisms of right ventricular dysfunction, contrasting mechanisms of RV adaptation and injury in these 2 settings.

Development and comparison of a minimally-invasive model of autologous clot pulmonary embolism in Sprague-Dawley and Copenhagen rats.

BACKGROUND: Experimental models of pulmonary embolism (PE) that produce pulmonary hypertension (PH) employ many different methods of inducing acute pulmonary occlusion. Many of these models induce PE with intravenous injection of exogenous impervious objects that may not completely reproduce the physiological properties of autologous thromboembolism. Current literature lacks a simple, well-described rat model of autlogous PE. OBJECTIVE: Test if moderate-severity autologous PE in Sprague-Dawley (SD) and Copenhagen (Cop) rats can produce persistent PH. METHODS: blood was withdrawn from the jugular vein, treated with thrombin-Ca++ and re-injected following pretreatment with tranexamic acid. Hemodynamic values, clot weights and biochemical measurements were performed at 1 and 5 days. RESULTS: Infusion of clot significantly increased the right ventricular peak systolic pressure to 45-55 mm Hg, followed by normalization within 24 hours in SD rats, and within 5 days in COP rats. Clot lysis was 95% (24 hours) and 97% (5 days) in SD rats and was significantly lower in COP rats (70%, 24 hours; 87% 5 days). Plasma D-dimer was elevated in surgical sham animals and was further increased 8 hours after pulmonary embolism. Neither strain showed a significant increase in bronchoalveolar chemotactic activity, myeloperoxidase activity, leukocyte infiltration, or chemokine accumulation, indicating that there was no significant pulmonary inflammation. CONCLUSIONS: Both SD and COP rats exhibited near complete fibrinolysis of autologous clot PE within 5 days. Neither strain developed persistent PH. Experimental models of PE designed to induce sustained PH and a robust inflammatory response appear to require significant, persistent pulmonary vascular occlusion.

Transcriptional changes in right ventricular tissues are enriched in the outflow tract compared with the apex during chronic pulmonary embolism in rats.

Moderate to severe pulmonary embolism (PE) can cause pulmonary arterial hypertension and right ventricular (RV) heart damage. Previous studies from our laboratory indicate that the basal outflow tract of the RV is injured and has acute inflammation followed by tissue remodeling while the apex appears normal. The present studies examine transcription responses to chronic PE in RV apex and outflow tracts using DNA microarrays to identify transcription responses by region. Changes predominated in the RV outflow tract (8,575 genes showed >/=1.5-fold expression change). Gene ontology and KEGG analyses indicated a significant decrease in genes involved in cellular respiration and energy metabolism and increases in inflammatory cell adhesion molecules and extracellular matrix proteins. Signal pathways for wound healing such as fibroblast growth factor, collagen synthesis, and CCN proteins (named for the first three members of the family: cysteine-rich protein 61, connective tissue growth factor, and nephroblastoma overexpressed gene) were strongly upregulated. In comparison, few genes (422) showed significant change in the RV apex tissue. Apex-selective genes included two genes affecting metabolism and a stretch-sensitive transcription factor (ankyrin repeat domain 1). We conclude that the RV outflow tract is subject to strong proinflammatory and profibrotic remodeling transcriptional responses in chronic PE. Severe loss of genes involved in cellular respiration is consistent with previous histology indicating a shift in cell types present within the outflow tract tissue away from highly energy-dependant cardiomyocytes to less metabolically active cells during remodeling. The apex region of the RV had few compensating adaptations.

Proinflammatory events in right ventricular damage during pulmonary embolism: effects of treatment with ketorolac in rats.

Right ventricular (RV) damage contributes to poor clinical outcome after pulmonary embolism (PE). Our studies show that neutrophils contribute to RV dysfunction in rat PE. Present studies examine effects of the nonsteroidal anti-inflammatory drug, ketorolac, upon RV inflammation and dysfunction. RV inflammatory gene expression significantly increased 6 and 18 hours after PE [cytokine-induced neutrophil chemoattractant-1 (CINC-1) 18-fold and 24-fold; cyclooxygenase-2 21-fold and 32-fold]. Eighteen hours after PE, there was significant upregulation of adhesion molecules (selectin E 18-fold; intercellular adhesion molecule 1 14-fold), influx of neutrophils (myeloperoxidase activity 21-fold), depressed RV function (RV peak systolic pressure = 24 +/- 3 vs. 40 +/- 1 mm Hg; maximum rate of pressure development = 444 +/- 79 vs. 1533 +/- 146; maximum rate of pressure decrease = -357 +/- 50 vs. -651 +/- 44), and release of cardiac troponin I (7.8 +/- 1.9 ng/mL) compared with vehicle. Ketorolac (10 mg/kg, intraperitoneally) significantly reduced expression of CINC-1, cyclooxygenase-2, selectin E, and intercellular adhesion molecule 1, lowered neutrophil influx, improved RV function (RV peak systolic pressure was 34 +/- 3 mm Hg; maximum rate of pressure development = 1288 +/- 146; maximum rate of pressure decrease = -611 +/- 92), and marginally reduced cardiac troponin I release (P < 0.07) compared with PE alone. Ketorolac reduced CINC-1 stimulated chemotaxis of isolated neutrophils. PE converted cardiac tissue into a proinflammatory phenotype. Ketorolac reduced RV inflammatory genes, reduced neutrophil influx, and improved RV function in rat PE.

Transcriptional profile of right ventricular tissue during acute pulmonary embolism in rats.

Acute pulmonary embolism (PE) is the third leading cause of cardiovascular death in the United States. Moderate to severe PE can cause pulmonary arterial hypertension (PH) with resultant right ventricular (RV) heart damage. The mechanisms leading to RV failure after PE are not well defined, although it is becoming clear that PH-induced inflammatory responses are involved. We previously demonstrated profound neutrophil-mediated inflammation and RV dysfunction during PE that was associated with increased expression of several chemokine genes. However, a complete assessment of transcriptional changes in RVs during PE is still lacking. We have now used DNA microarrays to assess the alterations in gene expression in RV tissue during acute PE/PH in rats. Key results were confirmed with real-time RT-PCR. Nine CC-chemokine genes (CCL-2, -3, -4, -6, -7, -9, -17, -20, -27), five CXC-chemokine genes (CXCL-1, -2, -9, -10, -16), and the receptors CCR1 and CXCR4 were upregulated after 18 h of moderate PE, while one C-chemokine (XCL-1) and one CXC-chemokine (CXCL-12) were downregulated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated increased expression of many inflammatory genes. There was also a major shift in the expression of components of metabolic pathways, including downregulation of fatty acid transporters and oxidative enzymes, a change in glucose transporters, and upregulation of stretch-sensing and hypoxia-inducible transcription factors. This pattern suggests an extensive shift in cardiac physiology favoring the expression of the "fetal gene program."

Tissue-specific expression of ALA synthase-1 and heme oxygenase-1 and their expression in livers of rats chronically exposed to ethanol.

5-Aminolevulinic acid synthase-1 (ALAS1) and heme oxygenase-1 (HO-1) are the rate-controlling enzymes for heme biosynthesis and degradation, respectively. Expression of these two genes showed tissue-specific expression pattern at both mRNA and protein levels in selected non-treated rat tissues. In the livers of rats receiving oral ethanol for 10 weeks, ALAS1 mRNA levels were increased by 65%, and the precursor and mature ALAS1 protein levels were increased by 1.8- and 2.3-fold, respectively, while no changes were observed in HO-1 mRNA and protein levels, compared with pair-fed controls. These results provide novel insights into the effects of chronic ethanol consumption on hepatic heme biosynthesis and porphyrias.

Early alterations in platelet mitochondrial function are associated with survival and organ failure in patients with septic shock.

INTRODUCTION: The objective of the study is to determine if changes in platelet mitochondrial function in patients with sepsis are present early after presentation and the association of these changes with clinical outcomes and systemic metabolic function. MATERIALS AND METHODS: This is a prospective observational cohort study of a convenience sample of patients with severe sepsis. Mitochondrial function of intact, nonpermeabilized platelets suspended in their own plasma was estimated using high-resolution respirometry. Unstimulated basal respiration, oligomycin-induced state 4, and maximal respiratory rate after serial titrations of carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone were measured. Organ failure was estimated using Sequential Organ Failure Assessment score, and patients were followed up until 28 days to determine survival. Lactate levels were measured in all patients, and a subset of patients had lactate/pyruvate (L/P) ratios measured. RESULTS: Twenty-eight patients were enrolled, 21 of whom survived. Initial Sequential Organ Failure Assessment score and lactate levels were 8.5 (interquartile range [IQR], 6-10) and 2.3 (IQR, 1.2-3.5) respectively, whereas the median L/P ratio was 23.4 (IQR, 15.2-38). Basal and maximal respiratory rates were significantly higher among nonsurvivors compared to survivors (P = .02 and P = .04), whereas oligomycin-induced state 4 respiration was not statistically different between groups (P = .15). We found a significant association between maximal respiration and organ failure (P = .03) and both basal and maximal rates with initial lactate level (P = .04, P = .02), but not with L/P ratio. CONCLUSIONS: Differences in platelet mitochondrial function between survivors and nonsurvivors are present very early in the hospital course and are associated with organ failure and lactate.

Leukocyte expression of heme oxygenase-1 [hmox1] varies inversely with severity of tricuspid regurgitation in acute pulmonary embolism.

OBJECTIVE: Pulmonary embolism (PE) can cause intracardiac hemolysis and increased plasma hemoglobin and arginase-1, which can worsen pulmonary vasoconstriction. We test the hypothesis that patients with PE that causes tricuspid regurgitation (TR), indicative of higher pulmonary arterial pressures, have decreased leukocyte expression of hmox-1 compared with patients with PE and no TR and patients without PE. DESIGN: Prospective, noninterventional study. PATIENTS: Normotensive patients with suspected PE (n=87) who underwent CT pulmonary angiography and transthoracic Doppler-echocardiography. MEASUREMENTS: Significant TR was defined as a jet velocity >2.7m/s. Leukocyte expression of hmox-1, haptoglobin, haptoglobin related gene, the haptoglobin receptor, CD163 and cox-2 genes were assessed by quantitative rtPCR, and the hmox-1 promoter was examined for the -413 A→T SNP and GT repeat polymorphisms. RESULTS: Of the 44 (50%) with PE+, 22 had TR+, and their mean pulmonary vascular occlusion (39±32%) did not differ significantly from patients who were TR- (28±26%, P=0.15). Patients with PE+ and TR+ had significantly lower expression of hmox-1 and haptoglobin genes than patients without PE+ and no TR. Expression of hmox-1 varied inversely with TR velocity (r(2)=0.45, P<0.001) for PE+ (n=22) but not patients without PE. Hmox-1 expression did not vary significantly with genotype. Cox-2 did not differ between groups and had no correlation with TR. CONCLUSIONS: Severity of TR varied inversely with hmox-1 expression, suggesting that hmox-1 expression affects pulmonary vascular reactivity after PE.

Cardiac UCP2 expression and myocardial oxidative metabolism during acute septic shock in the rat.

UNLABELLED: Septic shock decreases cardiac hydraulic work relative to the rate of myocardial oxygen consumption, causing decreased mechanical efficiency (hydraulic work/myocardial oxygen consumption). This study tested whether the mitochondrial uncoupling protein UCP2 was responsible for decreased cardiac mechanical efficiency after polymicrobial septic shock. Sepsis was initiated in ketamine/xylazine-anesthetized rats by cecal ligation and puncture (CLP). Steady-state mRNA content was quantified by Northern blot analysis, and protein content was estimated by western blot. Additional hearts were removed after 12 h and perfused in working mode to measure work (mmHg x mL/min/100 g dry wt) and efficiency (CE = work/oxygen consumption, %). The 72-h mortality rate was 80%, and deaths occurred between 12-32 h. Cardiac work (152 +/- 15, shock vs. 235 +/- 16, control; P < 0.05) and cardiac efficiency (4.0 +/- 0.4 vs. 5.6 +/- 0.3; P < 0.05) were significantly decreased when hearts were isolated 12 h after CLP. Myocardial UCP2 mRNA expression was increased by 52% (12 h) compared with control hearts; however, there was no detectable UCP2 protein in mitochondria isolated from either control or septic hearts. CONCLUSIONS: Although polymicrobial sepsis decreased cardiac mechanical efficiency and increased UCP-2 expression coincident with premortal hypothermia, we did not detect any evidence of UCP-2 protein in septic heart muscle. These data argue against the hypothesis that UCP-2 causes decreased cardiac mechanical efficiency in septic shock.

End tidal CO(2) is reduced during hypotension and cardiac arrest in a rat model of massive pulmonary embolism.

BACKGROUND: We investigated the effect of massive pulmonary embolism (MPE) on end tidal CO(2) (etCO(2)) and tested two hypotheses: (1) that etCO(2) can distinguish massive PE from hemorrhagic shock and (2) that PE with cardiac arrest reduces etCO(2) during resuscitation to a greater extent than arrhythmic cardiac arrest. METHODS: Anesthetized, mechanically ventilated rats (N=10 per group), were subjected to either graded PE (latex microspheres), or graded hemorrhagic shock to produce a final mean arterial blood pressure, (MAP) of 40 mmHg; a third group was subjected to surgical/anesthetic control conditions. Cardiac arrest was induced by the following methods: intravenous injection of a large bolus of microspheres in the PE group, aortic puncture in the hemorrhage group, and intravenous tetrodotoxin (TTX) to produce arrhythmic cardiac arrest in the control group. RESULTS: At a MAP of 40 mmHg, etCO(2) was significantly decreased in the PE group (18.3+/-1.9 torr) compared with both the hemorrhage (24.3+/-1.3) and the control group (35.0+/-1.3 torr; ANOVA P<0.001). The decreased etCO(2) occurred coincident with an increase in alveolar dead space fraction in the PE group. In the first minute of ventilation after cardiac arrest, the etCO(2) was significantly decreased in the PE group (6.5+/-0.9) versus both hemorrhage (16.5+/-1.1) and TTX (34.2+/-2.4 torr). CONCLUSIONS: Massive PE with shock decreases the etCO(2) and increases the dead space fraction to a greater extent than hemorrhagic shock at the same MAP. Cardiac arrest from PE is associated with extremely low etCO(2) readings during CPR.

Bench to bedside: the role of mitochondrial medicine in the pathogenesis and treatment of cellular injury.

Interest in the study of mitochondria has undergone a revival. The term mitochondrial medicine developed around evidence pointing to the mitochondria as a logical target for therapy. This article reviews the normal functions of mitochondria and integration of mitochondrial processes in cells. Changes in mitochondria that occur in ischemia and reperfusion, production of reactive oxygen species by mitochondria, stimulation of apoptosis, and roles of mitochondria in sepsis also are reviewed. The authors also review therapies that are based on targeting drugs to mitochondria, regulating calcium availability, substrate preferences, and activation of poly (ADP-ribose) polymerase and apoptosis. The purpose of this article is to provide a framework for emergency medicine academicians to understand the roles of mitochondria in pathology and to facilitate the transition of this information into therapeutic strategies based on mitochondrial medicine. For individuals interested in the biochemistry of mitochondria, knowledge of this fundamental organelle is expanding at a rapid rate.

Hyperbaric oxygen does not prevent neurologic sequelae after carbon monoxide poisoning.

UNLABELLED: Delayed neurologic sequelae occur in up to 40% of severe carbon monoxide (CO) poisonings. Conflicting clinical data support the efficacy of hyperbaric oxygen (HBO) therapy in the acute treatment of CO poisoning. OBJECTIVE: To determine whether oxygen therapy reduces neurologic sequelae after CO poisoning in mice. METHODS: Male Swiss-Webster mice were exposed to CO at 1,000 ppm for 40 minutes and then 50,000 ppm until loss of consciousness (LOC) (4-9 additional minutes). Total time of both phases of CO exposure was 40-49 minutes. Treatment included HBO with 3 atmospheres (ATA) 100% oxygen, normobaric oxygen (NBO) with 1 ATA 100% oxygen, or ambient air 15 minutes after LOC. All animals underwent passive avoidance training and memory was assessed by measuring step-down latency (SDL) and step-up latency (SUL) seven days following CO exposure. RESULTS: Carbon monoxide poisoning induced significant memory deficits (SDL(CO) = 156 sec; SUL(CO) = 75%) compared with nonpoisoned (NP) animals (SDL(NP) = 272 sec; SUL(NP) = 100%). Both HBO and NBO did not prevent these neurologic sequelae. Furthermore, no significant neurobehavioral differences were found between HBO and NBO. Histologic examination of the CA1 layer of the hippocampus for pyknotic cells showed significant damage from CO in the air-treated animals (9.6%) but not in the nonpoisoned animals (3.8%). No significant neuroprotection was seen histologically with NBO and HBO compared with ambient air. CONCLUSIONS: These results suggest that HBO is not effective in preventing neurologic sequelae in mice and that there is no benefit of HBO over NBO following severe CO neurotoxicity.

Mitochondrial bioenergetics, mass, and morphology are altered in cells of the degenerating human annulus.

Back pain and intervertebral disc degeneration have a growing socioeconomic healthcare impact. Information on mitochondrial function in human intervertebral disc cells, however, is surprisingly sparse. We assessed mitochondrial bioenergetics, mass, and ultrastructure in annulus cells cultured from human discs of varying degenerative stages. Citrate synthase activity (reflecting mitochondrial mass) declined significantly with increasing Thompson grade (p < 0.0001). Both mitochondrial (p = 0.009) and non-mitochondrial (p = 0.0029) respiration showed significant changes with increasing stages of disc degeneration. No significant relationships were found for the association of respiration data with herniated or non-herniated status, or with subject age. Examination of mitochondrial ultrastructure in cultured annulus cells revealed unusual features which included mitochondrial inclusion bodies, poorly defined cristae and dark staining. Findings reported here are novel and document biochemical, metabolic, and morphologic abnormalities in mitochondria in cells from more degenerated annulus cells. Data suggest that the disc degenerative, not age, is a major factor associated with mitochondrial impairment, and also implicate oxidative stress, driven by mitochondrial dysfunction, as a major component within the degenerating disc. Findings have relevance to advancements in cell-based therapies to treat disc degeneration.

Assessing the influence of insulation on intravenous fluid infusion temperature.

OBJECTIVES: Inducing therapeutic hypothermia using chilled saline in resuscitated cardiac arrest patients has been shown to be feasible and effective. Limited research exists assessing the efficiency of this cooling method. The objective of this study was to assess the change in temperature of 4°C saline upon exiting an infusion set in the laboratory setting while varying conditions of fluid delivery. METHODS: Efficiency was studied by assessing change in fluid temperature (°C) during the infusion under four laboratory conditions. Each condition was performed four times using 1-L bags of normal saline. Fluid was infused into a 1000-mL beaker through 10 gtt/mL tubing. Flow rate was controlled using a tubing clamp and in-line transducer with a flow meter, while temperature was continuously monitored in a side port at the terminal end of the intravenous (IV) tubing using a digital thermometer. The four conditions included different insulation methods. Descriptive statistics and analysis of variance were performed to assess changes in fluid temperature. RESULTS: The mean (±SD) fluid temperature at time 0 was 3.2°C (95% confidence interval [CI] = 3.0 to 3.4 °C) with no significant difference in starting temperature between groups (p = 0.45). When flow rate was constant, it was determined that fluid temperatures were significantly cooler when infused using a chilled, gel-filled sleeve around the saline bag (p < 0.006). CONCLUSIONS: In a laboratory setting, the most efficient method of infusing cold fluid appears to be a method that both keeps the bag of fluid insulated and infused at a faster rate.

Proteomics of microparticles after experimental pulmonary embolism.

INTRODUCTION: Microparticles (MPs) are small fragments of apoptotic or activated cells that may contribute to pathological processes in cardiovascular diseases. In studies of MPs in clinical cohorts, it is unclear if observed changes in MP composition are a cause or a result of the cardiovascular disease being studied. The present studies employed a well-characterized rat model of experimental pulmonary embolism (PE) to determine if there were changes in MP characteristics as a result of pulmonary vascular occlusion. METHODS: PE was produced by infusing 25 µm polystyrene microspheres into the jugular vein of anesthetized rats. MPs were isolated by differential centrifugation of arterial blood 18 hr after PE. Proteins were separated by 1D gel electrophoresis and identified from tryptic digests by ultraperformance liquid chromatography (UPLC) coupled with tandem mass spectrometry. Statistical analysis was conducted using the Power Law Global Error Model (PLGEM). Changes in two proteins were confirmed by Western blot. RESULTS: Experimental PE produced pulmonary hypertension, mild systemic hypotension, hypoxia, hypercapnia and lactic acidosis. MPs showed significant elevation in proteins involved in clotting (fibronectin precursor, fibrinogen alpha, beta and gamma and von Willebrand factor) and several macroglobulin proteins, such as alpha-2-macroglobulin precursor compared with vehicle-treated control rats. Consistent with recent observations of hemolysis in PE, haptoglobin precursor protein, a major protein of hemoglobin clearance, decreased significantly in the PE animals. Plasma d-Dimer concentrations were significantly elevated, indicating that experimental PE produced a pro-coagulant state. CONCLUSIONS: These findings suggest that experimental PE produced significant, changes in MP characteristics to a prothrombotic phenotype.