Resting-State Brain Activity for Early Prediction Outcome in Postanoxic Patients in a Coma with Indeterminate Clinical Prognosis.

BACKGROUND AND PURPOSE: Early outcome prediction of postanoxic patients in a coma after cardiac arrest proves challenging. Current prognostication relies on multimodal testing, using clinical examination, electrophysiologic testing, biomarkers, and structural MR imaging. While this multimodal prognostication is accurate for predicting poor outcome (ie, death), it is not sensitive enough to identify good outcome (ie, consciousness recovery), thus leaving many patients with indeterminate prognosis. We specifically assessed whether resting-state fMRI provides prognostic information, notably in postanoxic patients in a coma with indeterminate prognosis early after cardiac arrest, specifically for good outcome. MATERIALS AND METHODS: We used resting-state fMRI in a prospective study to compare whole-brain functional connectivity between patients with good and poor outcomes, implementing support vector machine learning. Then, we automatically predicted coma outcome using resting-state fMRI and also compared the prediction based on resting-state fMRI with the outcome prediction based on DWI. RESULTS: Of 17 eligible patients who completed the study procedure (among 351 patients screened), 9 regained consciousness and 8 remained comatose. We found higher functional connectivity in patients recovering consciousness, with greater changes occurring within and between the occipitoparietal and temporofrontal regions. Coma outcome prognostication based on resting-state fMRI machine learning was very accurate, notably for identifying patients with good outcome (accuracy, 94.4%; area under the receiver operating curve, 0.94). Outcome predictors using resting-state fMRI performed significantly better (P < .05) than DWI (accuracy, 60.0%; area under the receiver operating curve, 0.63). CONCLUSIONS: Indeterminate prognosis might lead to major clinical uncertainty and significant variations in life-sustaining treatments. Resting-state fMRI might bridge the gap left in early prognostication of postanoxic patients in a coma by identifying those with both good and poor outcomes.

Survival in patients without acute ST elevation after cardiac arrest and association with early coronary angiography: a post hoc analysis from the TTM trial.

PURPOSE: To investigate whether early coronary angiography (CAG) after out-of-hospital cardiac arrest of a presumed cardiac cause is associated with improved outcomes in patients without acute ST elevation. METHODS: The target temperature management after out-of-hospital cardiac arrest (TTM) trial showed no difference in all-cause mortality or neurological outcome between an intervention of 33 and 36 °C. In this post hoc analysis, 544 patients where the admission electrocardiogram did not show acute ST elevation were included. Early CAG was defined as being performed on admission or within the first 6 h after arrest. Primary outcome was mortality at the end of trial. A Cox proportional hazard model was created to estimate hazard of death, adjusting for covariates. In addition, a propensity score matched analysis was performed. RESULTS: A total of 252 patients (46 %) received early CAG, whereas 292 (54 %) did not. At the end of the trial, 122 of 252 patients who received an early CAG (48 %) and 159 of 292 patients who did not (54 %) had died. The adjusted hazard ratio for death was 1.03 in the group that received an early CAG; 95 % CI 0.80-1.32, p = 0.82. In the propensity score analysis early CAG was not significantly associated with survival. CONCLUSIONS: In this post hoc observational study of a large randomized trial, early coronary angiography for patients without acute ST elevation after out-of-hospital cardiac arrest of a presumed cardiac cause was not associated with improved survival. A randomized trial is warranted to guide clinical practice.

Analysis of the expression of nine secreted matrix metalloproteinases and their endogenous inhibitors in the brain of mice subjected to ischaemic stroke.

Matrix metalloproteinases (MMPs) are a family of more than twenty secreted and cell-surface endopeptidases. Among them, MMP2, MMP3 and MMP9 are involved in blood-brain barrier injury and neuronal death after cerebral ischaemia. On the other hand, very little is known about the expression of the other secreted MMPs. Herein, we compared the global changes in MMP1, MMP2, MMP3, MMP7, MMP8, MMP9, MMP10, MMP12 and MMP13, and their endogenous inhibitors TIMP1 and TIMP2, both at the mRNA and protein levels, during the hyperacute (6 h), acute (24 h) and subacute (72 h) stages following transient focal cerebral ischaemia and treatment with recombinant tissue plasminogen activator (rtPA). We observed a significant increase in MMP1, MMP2, MMP9, MMP10, MMP13 and TIMP1 levels during the acute stage of reperfusion, which was further amplified during the subacute stage for MMP1, MMP2, MMP10 and TIMP1. In general, no change of MMP3, MMP7, MMP8, MMP12 and TIMP2 was observed. However, rtPA treatment induced a rapid increase in MMP1/TIMP2, MMP2/TIMP2, MMP8/TIMP2 and MMP9/TIMP2 ratios during the hyperacute stage of reperfusion compared to saline treatment, which may have potential implications in the early disruption of the blood-brain barrier after rtPA treatment.

[Continuous EEG monitoring for aneurysmal subarachnoid hemorrhage]. / Intérêt du monitoring EEG continu dans la prise en charge de l'hémorragie sous-arachnoidienne.

Subarachnoid hemorrhage (SAH) still carries a high morbidity and mortality, despite improvement in surgical and medical management. Seizures and delayed cerebral ischemia (DCI) secondary to vasospasm or cortical spreading depression are frequent after SAH. Continuous EEG allows early detection of non-convulsive seizures or delayed cerebral ischemia and may become a promissing tool in the monitoring of SAH patients. However, its use in clinical practice is still limited because many resources are required for recording and analyzing continuous EEG. Moreover, we require more data to confirm the relationship between aggressive treatment of non-convulsive seizure or delayed cerebral ischemia triggered by continuous EEG and outcome.

[Adverse effects of proton pump inhibitors: should we worry about long-term exposure?]. / Effets indésirables des inhibiteurs de la pompe à proton : faut-il craindre de les prescrire au long cours ?

Long-term treatment with proton pump inhibitors (PPI) is becoming more prevalent. Although they are well tolerated in the short term, serious concerns about long-term use have arisen. Recent data suggest that the latter is associated with an increased risk for osteoporotic fracture (especially vertebral), Clostridium difficile infection and rebound acid hypersecretion after treatment discontinuation. Acute interstitial nephritis is rare but may progress to chronic renal failure. An increased risk of community-acquired pneumonia has not been established in the general population and seems limited to the most vulnerable patients. Consistent data are still missing to correctly assess the risk of iron deficiency, vitamin B12 deficiency or hypomagnesaemia and the risk of digestive malignant diseases, despite the pathophysiological basis that exists concerning gastric malignancy. Many drug interactions can occur on long-term treatment, including some that imply the cytochrome P450 enzymes. Finally, the risk-benefit balance for a chronic PPI use in children seems unfavorable in most cases.

Two structurally different T-type Ca 2+ channel inhibitors, mibefradil and pimozide, protect CA1 neurons from delayed death after global ischemia in rats.

Recent in vitro evidence suggests that T-type Ca(2+) channels are implicated in the mechanisms of ischemia-induced delayed neuronal cell death. The aim of this work was to study the neuroprotective potential of mibefradil and pimozide, both T-type Ca(2+) channel inhibitors, in an in vivo rat model of global ischemia. We performed blinded and randomized placebo vs. treatment experiments using 57 animals to test mibefradil and fourteen animals to test pimozide. Each treated animal received a single stereotactic intraventricular injection of mibefradil or intraperitoneal injection of pimozide prior to transient global cerebral ischemia. The primary endpoint was the number of neurons surviving in the CA1 region 72 h after insult as evaluated by NeuN-labeled cell counts. All physiological variables monitored immediately before and after ischemic insult were equivalent between all groups. Surviving neurons in the CA1 region were significantly more frequent in the treated groups compared to the placebo group (mibefradil: 36.8 ± 2.8 cells in a 200 × 100 µm counting area vs. placebo: 25.2 ± 3.2 [P < 0.01]; pimozide: 39.4 ± 1.12 vs. placebo: 27.8 ± 0.7 [P < 0.0001]). Thus, administration of mibefradil or pimozide effectively prevents neuronal death after ischemia in a rat model of global ischemia. This study provides further support for a neuroprotective effect of T-type Ca(2+) current inhibition during ischemia.

[Blood-brain barrier pathophysiology and ischaemic brain oedema]. / Physiopathologie de la barrière hématoencéphalique et oedème cérébral d'origine ischémique.

Cerebral oedema is a potentially lethal complication of brain infarction. Ischemia, by altering membrane ionic pump function, induces cell swelling and cytotoxic oedema. It also initiates early oxidative and inflammatory cascades leading to blood-brain barrier disruption, vasogenic oedema and haemorrhagic transformation. The mechanisms of blood-brain barrier disruption involve endothelial cell activation and endothelial basal membrane degradation by matrix metalloproteinases. Reperfusion by tissue plasminogen activators is the only treatment improving stroke prognosis. This treatment also increases vasogenic oedema and the risk of symptomatic haemorrhagic transformation, reducing the benefit of reperfusion. Experimental studies suggest that the inhibition of blood-brain barrier proteolysis reduces vasogenic oedema and the risk of haemorrhage. This recent progress in the understanding of blood-brain barrier disruption during ischaemia brings forward new therapeutic strategies using agents capable of interfering with the ischaemic cascade in order to increase the therapeutic window between the onset of ischaemia and thrombolytic reperfusion.

[Morphology and physiology of the blood-brain barrier]. / Morphologie et physiologie de la barrière hématoencéphalique.

The blood-brain barrier (BBB) is a complex biological system that consists of endothelial cells, pericytes and astrocytes, which are involved in the induction and maintenance of its physiological and ultrastructural characteristics. The BBB plays a primordial role in isolating the cerebral parenchyma as well as in controlling brain homeostasis by its selective permeability to nutriments and other molecules flowing through the cerebral microcapillaries. A better knowledge of this system is crucial in order to improve the efficiency of brain penetration by drugs, and in order to prevent BBB opening, leading to brain edema, in physiopathological situations such as brain ischemia, trauma or inflammatory processes.

Slaughterhouse blood as a perfusate for studying myocardial function under ischemic conditions.

Metabolic studies using the in vitro non-recirculating blood-perfused isolated heart model require large volumes of blood. The present study was designed to determine whether heterologous pig blood collected from a slaughterhouse can be used as perfusate for isolated pig hearts perfused under aerobic and constant reduced flow conditions. Eight isolated working pig hearts perfused for 90 min at a constant flow of 1.5 ml g(-1) min(-1) with non-recirculated blood diluted with Krebs-Henseleit bicarbonate buffer at a hematocrit of 23% were compared to eight hearts subjected to the same protocol but perfused only with Krebs-Henseleit bicarbonate buffer solution. Hearts were paced at 100 bpm and subjected to aerobic perfusion at 38 degrees C. Hearts were weighed before perfusion and at the end of the experiment and the results are reported as percent weight gain (mean +/- SD). Comparisons between groups were performed by the Student t-test (P<0.05). After 90 min of perfusion with modified Krebs-Henseleit, perfused hearts presented a larger weight gain than blood-perfused hearts (39.34 +/- 9.27 vs 23.13 +/- 5.42%, P = 0.003). Left ventricular end-diastolic pressure was higher in the modified Krebs-Henseleit-perfused group than in the blood group (2.8 +/- 0.4 vs 2.3 +/- 0.3 mmHg, respectively, P = 0.01). We conclude that heterologous blood perfusion, by preserving a more physiological myocardial water content, is a better perfusion fluid than modified Krebs-Henseleit solution for quantitative studies of myocardial metabolism and heart function under ischemic conditions.

Slaughterhouse blood as a perfusate for studying myocardial function under ischemic conditions

Metabolic studies using the in vitro non-recirculating blood-perfused isolated heart model require large volumes of blood. The present study was designed to determine whether heterologous pig blood collected from a slaughterhouse can be used as perfusate for isolated pig hearts perfused under aerobic and constant reduced flow conditions. Eight isolated working pig hearts perfused for 90 min at a constant flow of 1.5 ml g-1 min-1 with non-recirculated blood diluted with Krebs-Henseleit bicarbonate buffer at a hematocrit of 23 percent were compared to eight hearts subjected to the same protocol but perfused only with Krebs-Henseleit bicarbonate buffer solution. Hearts were paced at 100 bpm and subjected to aerobic perfusion at 38ºC. Hearts were weighed before perfusion and at the end of the experiment and the results are reported as percent weight gain (mean ± SD). Comparisons between groups were performed by the Student t-test (P<0.05). After 90 min of perfusion with modified Krebs-Henseleit, perfused hearts presented a larger weight gain than blood-perfused hearts (39.34 ± 9.27 vs 23.13 ± 5.42 percent, P = 0.003). Left ventricular end-diastolic pressure was higher in the modified Krebs-Henseleit-perfused group than in the blood group (2.8 ± 0.4 vs 2.3 ± 0.3 mmHg, respectively, P = 0.01). We conclude that heterologous blood perfusion, by preserving a more physiological myocardial water content, is a better perfusion fluid than modified Krebs-Henseleit solution for quantitative studies of myocardial metabolism and heart function under ischemic conditions

Matrix metalloproteinase inhibition prevents oxidative stress-associated blood-brain barrier disruption after transient focal cerebral ischemia.

Oxidative stress generated during stroke is a critical event leading to blood-brain barrier (BBB) disruption with secondary vasogenic edema and hemorrhagic transformation of infarcted brain tissue, restricting the benefit of thrombolytic reperfusion. In this study, the authors demonstrate that ischemia-reperfusion-induced BBB disruption in mice deficient in copper/zinc-superoxide dismutase (SOD1) was reduced by 88% ( P < 0.0001) and 73% ( P < 0.01), respectively, after 3 and 7 hours of reperfusion occurring after 1 hour of ischemia by the inhibition of matrix metalloproteinases. Accordingly, the authors show that local metalloproteinase-generated proteolytic imbalance is more intense in ischemic regions of SOD1 mice than in wild-type litter mates. Moreover, active in situ proteolysis is, for the first time, demonstrated in ischemic leaking capillaries that produce reactive oxygen species. By showing that oxidative stress mediates BBB disruption through metalloproteinase activation in experimental ischemic stroke, this study provides a new target for future therapeutic strategies to prevent BBB disruption and potentially reperfusion-triggered intracerebral hemorrhage.

Oxidative cellular damage and the reduction of APE/Ref-1 expression after experimental traumatic brain injury.

The DNA repair enzyme, apurinic/apyrimidinic endonuclease (or redox effector factor-1, APE/Ref-1), is involved in base excision repair of apurinic/apyrimidinic sites after oxidative DNA damage. We investigated the expression of APE/Ref-1 and its relationship to oxidative stress after severe traumatic brain injury produced by controlled cortical impact in normal mice, and in mice over- or underexpressing copper-zinc superoxide dismutase (SOD1TG and SOD1KO, respectively). Oxygen free radical-mediated cellular injury was visualized with 8-hydroxyguanine immunoreactivity as a marker for DNA oxidation, and in situ hydroethidine oxidation as a marker for superoxide production. After trauma there was a reduced expression of APE/Ref-1 in the ipsilateral cortex and hippocampus that correlated with the gene dosage levels of cytosolic superoxide dismutase. The decrease in APE/Ref-1 expression preceded DNA fragmentation. There was also a close correlation between APE/Ref-1 protein levels 4 h after trauma and the volume of the lesion 1 week after injury. Our data have demonstrated that reduction of APE/Ref-1 protein levels correlates closely with the level of oxidative stress after traumatic brain injury. We suggest that APE/Ref-1 immunoreactivity is a sensitive marker for oxidative cellular injury.

Prolonged hypoxia during cell development protects mature manganese superoxide dismutase-deficient astrocytes from damage by oxidative stress.

Mouse astrocytes deficient in the mitochondrial form of superoxide dismutase do not grow in culture under 20% atmospheric O2 levels. By flow cytometry, immunocytochemistry, and enzymatic analysis we have shown that the oxygen block of cell division is due to a decrease in the number of cells entering the S phase of the cell cycle and is concomitant with higher DNA oxidation and impairment of mitochondrial functions. Seeding the cells under 5% O2 until the cultures become confluent can circumvent this problem. An initial hypoxic environment increases the resistance of manganese superoxide dismutase-deficient astrocytes to superoxide radicals artificially produced by paraquat treatment, preserves respiratory activity, and allows normoxic division during a subsequent passage. DNA oxidation is then not higher than in wild-type control cells. However, the adaptation of the cells is not due to compensation by other enzymes of the antioxidant defense system and is specific to cells totally lacking manganese superoxide dismutase. Alteration of the phenotype by prior hypoxia exposure in the SOD2-deficient mutant provide a unique model to study adaptative mechanisms of cellular resistance to oxygen toxicity.

Matrix metalloproteinases correlate with alveolar-capillary permeability alteration in lung ischemia-reperfusion injury.

BACKGROUND: Matrix metalloproteinases (MMPs) are able to degrade the endothelial basal lamina and increase vascular permeability. METHODS: In a porcine model of isolated-reperfused lung, we studied the alveolar-capillary permeability and the zymographic expression of MMP-9 and MMP-2 in the bronchoalveolar lavage fluid of lungs submitted ex vivo to ischemia in three preservation solutions [modified Euro-Collins (EC), low-potassium-dextran, modified-blood]. Twenty-two pigs were randomly divided into three groups according to the preservation solution used. One lung of each pig was rapidly reperfused and analyzed (control lung) although the other lung was reperfused and analyzed after 8 hr of ischemia (ischemic lung). RESULTS: Alveolar-capillary permeability, evaluated by the transferrin leak index, was increased after 8 hr of ischemia compared with controls in the three groups, but was significantly higher in the modified EC group. In the EC group, after 8 hr of ischemia, both proMMP-9 and MMP-9 increased significantly (8.8- and 22-fold, respectively) compared with controls and this increase correlated with the transferrin leak index. Neither proMMP-9 nor MMP-9 increased with the other two preservation solutions. The MMP-2 increase after ischemia was smaller and was also restricted to the EC group. CONCLUSION: MMP expression is enhanced during lung ischemia-reperfusion, especially in the presence of EC and this phenomenon correlates with the alteration of alveolar-capillary permeability.

Effect of hypotension severity on hippocampal CA1 neurons in a rat global ischemia model.

Neuronal death in the hippocampal CA1 subregion has been shown to occur in a delayed manner after transient global ischemia. The 2-vessel occlusion model is one of the most frequently used global ischemia paradigms in rodents. Although researchers often fail to induce bilateral delayed CA1 neuronal death, the importance of hypotension severity has not been fully discussed. We induced 10 min of global ischemia with 2-vessel occlusion and various severities of hypotension in rats, and the subsequent neuronal damage and neurogenesis in the hippocampal CA1 pyramidal cell layer were immunohistochemically studied. Neuronal apoptosis after global ischemia was also characterized by terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL). The mean arterial blood pressure of 31-35 mmHg was the most appropriate range of hypotension in this model because of low mortality and consistent bilateral CA1 injury. Most of the neurons in the CA1 pyramidal cell layer lost neuron specific nuclear protein and became TUNEL-positive 3 days after ischemia. There was no evidence of apoptosis or neurogenesis at 7-28 days. There were ischemia-tolerant neurons in the CA1 pyramidal cell layer that survived delayed neurodegeneration, however, further studies are necessary to characterize the property of these neurons.

Overexpression of copper/zinc superoxide dismutase does not prevent neonatal lethality in mutant mice that lack manganese superoxide dismutase.

There are two types of intracellular superoxide dismutases: the mitochondrial manganese SOD (MnSOD) and the cytoplasmic copper/zinc SOD (CuZnSOD). Mutant mice that lack MnSOD die shortly after birth because of cardiomyopathy and mitochondrial injury. In order to verify if CuZnSOD could compensate for MnSOD deficiency, a new mutant mouse that overexpresses CuZnSOD but is deficient in MnSOD was generated by crossing MnSOD knockout mice with CuZnSOD transgenic mice. CuZnSOD activity was significantly increased in the blood, brain, liver, and heart of MnSOD knockout, CuZnSOD transgenic mice when compared with nontransgenic mice. However, overexpression of CuZnSOD did not prevent neonatal lethality in mice that lack MnSOD, nor did it prevent oxidative aconitase inactivation, nor did it rescue MnSOD-deficient astrocytes in culture. Based on our findings, which emphasize the strong enzymatic compartmentalization of CuZnSOD and MnSOD, therapeutic antioxidant strategies should consider the final intracellular localization of the antioxidant used, especially when those strategies are directed against mitochondrial diseases.

Overexpression of copper and zinc superoxide dismutase in transgenic mice prevents the induction and activation of matrix metalloproteinases after cold injury-induced brain trauma.

Matrix metalloproteinases (MMPs), a family of proteolytic enzymes which degrade the extracellular matrix, are implicated in blood-brain barrier disruption, which is a critical event leading to vasogenic edema. To investigate the role of reactive oxygen species (ROS) in the expression of MMPs in vasogenic edema, the authors measured gelatinase activities before and after cold injury (CI) using transgenic mice that overexpress superoxide dismutase-l. A marked induction of pro-gelatinase B (pro-MMP-9) was seen 2 hours after CI and was maximized at 12 hours in wild-type mice. The pro-MMP-9 level was significantly lower in transgenic mice 4 hours (P < 0.001) and 12 hours (P < 0.05) after CI compared to wild-type mice. The activated MMP-9 was detected from 6 to 24 hours after injury. A mild induction of pro-gelatinase A (pro-MMP-2) was seen at 6 hours and was sustained until 7 days. In contrast. the activated form of MMP-2 appeared at 24 hours, was maximized at 7 days, and was absent in transgenic mice. Western blot analysis showed that the tissue inhibitors of metalloproteinases were not modified after CI. The results suggest that ROS production after CI may contribute to the induction and/or activation of MMPs and could thereby exacerbate endothelial cell injury and the development of vasogenic edema after injury. Key Words: Metalloproteinases-Brain-Vasogenic edema-Reactive oxygen species-Superoxide dismutase.

Early appearance of activated matrix metalloproteinase-9 and blood-brain barrier disruption in mice after focal cerebral ischemia and reperfusion.

Blood-brain barrier (BBB) disruption is thought to play a critical role in the pathophysiology of ischemia/reperfusion. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that can degrade all the components of the extracellular matrix when they are activated. Gelatinase A (MMP-2) and gelatinase B (MMP-9) are able to digest the endothelial basal lamina, which plays a major role in maintaining BBB impermeability. The present study examined the expression and activation of gelatinases before and after transient focal cerebral ischemia (FCI) in mice. Adult male CD1 mice were subjected to 60 min FCI and reperfusion. Zymography was performed from 1 to 23 h after reperfusion using the protein extraction method with detergent extraction and affinity-support purification. MMP-9 expression was also examined by both immunohistochemistry and Western blot analysis, and tissue inhibitors to metalloproteinase-1 was measured by reverse zymography. The BBB opening was evaluated by the Evans blue extravasation method. The 88-kDa activated MMP-9 was absent from the control specimens, while it appeared 3 h after transient ischemia by zymography. At this time point, the BBB permeability alteration was detected in the ischemic brain. Both pro-MMP-9 (96 kDa) and pro-MMP-2 (72 kDa) were seen in the control specimens, and were markedly increased after FCI. A significant induction of MMP-9 was confirmed by both immunohistochemistry and Western blot analysis. The early appearance of activated MMP-9, associated with evidence of BBB permeability alteration, suggests that activation of MMP-9 contributes to the early formation of vasogenic edema after transient FCI.