Targeting autophagy to prevent neonatal stroke damage.

Cell death due to cerebral ischemia has been attributed to necrosis and apoptosis, but autophagic mechanisms have recently been implicated as well. Using rats exposed to neonatal focal cerebral ischemia, we have shown that lysosomal and autophagic activities are increased in ischemic neurons, and have obtained strong neuroprotection by post-ischemic inhibition of autophagy.

Role of Mitogen-Activated Protein Kinases in Myocardial Ischemia-Reperfusion Injury during Heart Transplantation.

In solid organ transplantation, ischemia/reperfusion (IR) injury during organ procurement, storage and reperfusion is an unavoidable detrimental event for the graft, as it amplifies graft inflammation and rejection. Intracellular mitogen-activated protein kinase (MAPK) signaling pathways regulate inflammation and cell survival during IR injury. The four best-characterized MAPK subfamilies are the c-Jun NH2-terminal kinase (JNK), extracellular signal- regulated kinase-1/2 (ERK1/2), p38 MAPK, and big MAPK-1 (BMK1/ERK5). Here, we review the role of MAPK activation during myocardial IR injury as it occurs during heart transplantation. Most of our current knowledge regarding MAPK activation and cardioprotection comes from studies of preconditioning and postconditioning in nontransplanted hearts. JNK and p38 MAPK activation contributes to myocardial IR injury after prolonged hypothermic storage. p38 MAPK inhibition improves cardiac function after cold storage, rewarming and reperfusion. Small-molecule p38 MAPK inhibitors have been tested clinically in patients with chronic inflammatory diseases, but not in transplanted patients, so far. Organ transplantation offers the opportunity of starting a preconditioning treatment before organ procurement or during cold storage, thus modulating early events in IR injury. Future studies will need to evaluate combined strategies including p38 MAPK and/or JNK inhibition, ERK1/2 activation, pre- or postconditioning protocols, new storage solutions, and gentle reperfusion.

Transcranial Doppler for predicting delayed cerebral ischemia after subarachnoid hemorrhage.

OBJECTIVE: Transcranial Doppler (TCD) is widely used to monitor the temporal course of vasospasm after subarachnoid hemorrhage (SAH), but its ability to predict clinical deterioration or infarction from delayed cerebral ischemia (DCI) remains controversial. We sought to determine the prognostic utility of serial TCD examination after SAH. METHODS: We analyzed 1877 TCD examinations in 441 aneurysmal SAH patients within 14 days of onset. The highest mean blood flow velocity (mBFV) value in any vessel before DCI onset was recorded. DCI was defined as clinical deterioration or computed tomographic evidence of infarction caused by vasospasm, with adjudication by consensus of the study team. Logistic regression was used to calculate adjusted odds ratios for DCI risk after controlling for other risk factors. RESULTS: DCI occurred in 21% of patients (n = 92). Multivariate predictors of DCI included modified Fisher computed tomographic score (P = 0.001), poor clinical grade (P = 0.04), and female sex (P = 0.008). After controlling for these variables, all TCD mBFV thresholds between 120 and 180 cm/s added a modest degree of incremental predictive value for DCI at nearly all time points, with maximal sensitivity by SAH day 8. However, the sensitivity of any mBFV more than 120 cm/s for subsequent DCI was only 63%, with a positive predictive value of 22% among patients with Hunt and Hess grades I to III and 36% in patients with Hunt and Hess grades IV and V. Positive predictive value was only slightly higher if mBFV exceeded 180 cm/s. CONCLUSION: Increased TCD flow velocities imply only a mild incremental risk of DCI after SAH, with maximal sensitivity by day 8. Nearly 40% of patients with DCI never attained an mBFV more than 120 cm/s during the course of monitoring. Given the poor overall sensitivity of TCD, improved methods for identifying patients at high risk for DCI after SAH are needed.

New evidence of neuroprotection by lactate after transient focal cerebral ischaemia: extended benefit after intracerebroventricular injection and efficacy of intravenous administration.

BACKGROUND: Lactate protects mice against the ischaemic damage resulting from transient middle cerebral artery occlusion (MCAO) when administered intracerebroventricularly at reperfusion, yielding smaller lesion sizes and a better neurological outcome 48 h after ischaemia. We have now tested whether the beneficial effect of lactate is long-lasting and if lactate can be administered intravenously. METHODS: Male ICR-CD1 mice were subjected to 15-min suture MCAO under xylazine + ketamine anaesthesia. Na L-lactate (2 µl of 100 mmol/l) or vehicle was administered intracerebroventricularly at reperfusion. The neurological deficit was evaluated using a composite deficit score based on the neurological score, the rotarod test and the beam walking test. Mice were sacrificed at 14 days. In a second set of experiments, Na L-lactate (1 µmol/g body weight) was administered intravenously into the tail vein at reperfusion. The neurological deficit and the lesion volume were measured at 48 h. RESULTS: Intracerebroventricularly injected lactate induced sustained neuroprotection shown by smaller neurological deficits at 7 days (median = 0, min = 0, max = 3, n = 7 vs. median = 2, min = 1, max = 4.5, n = 5, p < 0.05) and 14 days after ischaemia (median = 0, min = 0, max = 3, n = 7 vs. median = 3, min = 0.5, max = 3, n = 7, p = 0.05). Reduced tissue damage was demonstrated by attenuated hemispheric atrophy at 14 days (1.3 ± 4.0 mm(3), n = 7 vs. 12.1 ± 3.8 mm(3), n = 5, p < 0.05) in lactate-treated animals. Systemic intravenous lactate administration was also neuroprotective and attenuated the deficit (median = 1, min = 0, max = 2.5, n = 12) compared to vehicle treatment (median = 1.5, min = 1, max = 8, n = 12, p < 0.05) as well as the lesion volume at 48 h (13.7 ± 12.2 mm(3), n = 12 vs. 29.6 ± 25.4 mm(3), n = 12, p < 0.05). CONCLUSIONS: The beneficial effect of lactate is long-lasting: lactate protects the mouse brain against ischaemic damage when supplied intracerebroventricularly during reperfusion with behavioural and histological benefits persisting 2 weeks after ischaemia. Importantly, lactate also protects after systemic intravenous administration, a more suitable route of administration in a clinical emergency setting. These findings provide further steps to bring this physiological, commonly available and inexpensive neuroprotectant closer to clinical translation for stroke.

Severe ischemia of the hand following intra-arterial promazine injection: effects of vasodilation, anticoagulation, and local thrombolysis with tissue-type plasminogen activator.

Promazine hydrochloride was injected accidentally in the antecubital artery of a 42-year-old woman, resulting in severe ischemia of the second and third fingers of her right hand which lasted for four days before she was hospitalized. Vasodilation by combining axillary plexus block and intravenous sodium nitroprusside did not improve ischemia and local thrombolysis was performed using recombinant tissue-type plasminogen activator (50 mg over 8 hours), resulting in normalization of digital pressure in one of the two affected fingers. The outcome was favourable and amputation could be avoided.

Thoracic aortic dissection associated with cocaine abuse.

Cardiovascular complications of cocaine abuse include myocardial ischemia and infarction, dysrhythmias, cardiomyopathies and aortic dissection. The case in point pertains to a 26-year-old, Caucasian male, substance abuser who suffered a thoracic aortic dissection following the use of crack cocaine. The autopsy and histological findings showed a connective tissue abnormality including a focal microcystic medial necrosis and a fragmentation of the elastic fibers in the arterial walls. Blood concentrations of cocaine and benzoylecgonine, taken individually, were considered to be within a potentially toxic range. Blood concentrations of methadone also indicated use of this drug at the same time. The small amounts of morphine found in the blood and urine were compatible with heroine or morphine use more than 24 h before death.

Characterization of fortuitously discovered focal liver lesions: additional information provided by shearwave elastography.

OBJECTIVES: To prospectively assess the stiffness of incidentally discovered focal liver lesions (FLL) with no history of chronic liver disease or extrahepatic cancer using shearwave elastography (SWE). METHODS: Between June 2011 and May 2012, all FLL fortuitously discovered on ultrasound examination were prospectively included. For each lesion, stiffness was measured (kPa). Characterization of the lesion relied on magnetic resonance imaging (MRI) and/or contrast-enhanced ultrasound, or biopsy. Tumour stiffness was analysed using ANOVA and non-parametric Mann-Whitney tests. RESULTS: 105 lesions were successfully evaluated in 73 patients (61 women, 84%) with a mean age of 44.8 (range: 20‒75). The mean stiffness was 33.3 ± 12.7 kPa for the 60 focal nodular hyperplasia (FNH), 19.7 ± 9.8 k Pa for the 17 hepatocellular adenomas (HCA), 17.1 ± 7 kPa for the 20 haemangiomas, 11.3 ± 4.3 kPa for the five focal fatty sparing, 34.1 ± 7.3 kPa for the two cholangiocarcinomas, and 19.6 kPa for one hepatocellular carcinoma (p < 0.0001). There was no difference between the benign and the malignant groups (p = 0.64). FNHs were significantly stiffer than HCAs (p < 0.0001). Telangiectatic/inflammatory HCAs were significantly stiffer than the steatotic HCAs (p = 0.014). The area under the ROC curve (AUROC) for differentiating FNH from other lesions was 0.86 ± 0.04. CONCLUSION: SWE may provide additional information for the characterization of FFL, and may help in differentiating FNH from HCAs, and in subtyping HCAs. KEY POINTS: ? SWE might be helpful for the characterization of solid focal liver lesions ? SWE cannot differentiate benign from malignant liver lesions ? FNHs are significantly stiffer than other benign lesions ? Telangiectatic/inflammatory HCA are significantly stiffer than steatotic ones.

The monocarboxylate transporter MCT4 : mechanism of regulation in astrocytes and its putative role in cerebral ischemia

Despite its small fraction of the total body weight (2%), the brain contributes for 20% and 25% respectively of the total oxygen and glucose consumption of the whole body. Indeed, glucose has been considered the energy substrate par excellence for the brain. However, evidence accumulated over the last half century revealed an important role for the monocarboxylate lactate in fulfilling the energy needs of neurons. This is particularly true during physiological neuronal activation and in pathological conditions. Lactate transport into and out of the cell is mediated by a family of proton-linked transporters called monocarboxylate transporters (MCTs). In the central nervous system, only three of them have been well characterized: MCT2 is the predominant neuronal isoform, while the other non¬neuronal cell types of the brain express the ubiquitous isoform MCT1. Quite recently, the MCT4 isoform has been described in astrocytes. Due to its high transport capacity compared to the other two isoforms, MCT4 is particularly adapted for glycolytic cells. Because of its recent discovery in the brain, nothing was known about its regulation in the central nervous system. Here we show that MCT4 is regulated by oxygen levels in primary cultures of astrocytes in a time- and concentration-dependent manner via the hypoxia inducible factor-la (HIF-la). Moreover, we showed that MCT4 expression is essential for astrocyte survival under low oxygen conditions. In parallel, we investigated the possible implication of the pyruvate kinase isoform Pkm2, a strong enhancer of glycolysis, in its regulation. Then we showed that MCT4 expression, as well as the expression of the other two MCT isoforms, is altered in a murine model of stroke. Surprisingly, neurons started to express MCT4, as well as MCT1, under such conditions. Altogether, these data suggest that MCT4, due to its high transport capacity for lactate, may be the isoform that enables cells to operate a major metabolic adaptation in response to pathological situations that alter metabolic homeostasis of the brain. -- Le cerveau représente 2% du poids corporel total, mais il contribue pour 20% de la consommation totale d'oxygène et 25% de celle de glucose au repos. Le glucose est considéré comme le substrat énergétique par excellence pour le cerveau. Néanmoins, depuis un demi- siècle maintenant, de plus en plus de travaux ont démontré que le lactate joue un rôle majeur dans le métabolisme cérébral et est capable du subvenir aux besoins énergétiques des neurones. Le lactate est tout particulièrement nécessaire pendant l'activation neuronale ainsi qu'en situation pathologique. Le transport du lactate à travers la barrière hématoencéphalique ainsi qu'à travers les membranes cellulaires est assuré par la famille des transporteurs aux monocarboxylates (MCTs). Dans le système nerveux central, uniquement trois d'entre eux ont été décrits: MCT2 est considéré comme le transporteur neuronal, alors que les autres types cellulaires qui constituent le cerveau expriment l'isoforme ubiquitaire MCT1. Récemment, l'isoforme MCT4 a été rapportée sur les astrocytes. Dû à sa grande capacité de transport pour le lactate, MCT4 est tout particulièrement adapté pour soutenir le métabolisme des cellules hautement glycolytiques, comme les astrocytes. En raison de sa toute récente découverte, les aspects comprenant sa régulation et son rôle dans le cerveau sont pour l'instant méconnus. Les résultats exposés dans ce travail démontrent dans un premier temps que l'expression de MCT4 est régulée par les niveaux d'oxygène dans les cultures d'astrocytes corticaux par le biais du facteur de transcription HIF-la. De plus, nous avons démontré que l'expression de MCT4 est essentielle à la survie des astrocytes quand le niveau d'oxygénation baisse. En parallèle, des résultats préliminaires suggèrent que l'isoforme 2 de la pyruvate kinase, un puissant régulateur de la glycolyse, pourrait jouer un rôle dans la régulation de MCT4. Dans la deuxième partie du travail nous avons démontré que l'expression de MCT4, ainsi que celle de MCT1 et MCT2, est altérée dans un modèle murin d'ischémie cérébrale. De façon surprenante, les neurones expriment MCT4 dans cette condition, alors que ce n'est pas le cas en condition physiologique. En tenant compte de ces résultats, nous suggérons que MCT4, dû à sa particulièrement grande capacité de transport pour le lactate, représente le MCT qui permet aux cellules du système nerveux central, notamment les astrocytes et les neurones, de s'adapter à de très fortes perturbations de l'homéostasie métabolique du cerveau qui surviennent en condition pathologique.

New genes for focal epilepsies with speech and language disorders.

The last 2 years have seen exciting advances in the genetics of Landau-Kleffner syndrome and related disorders, encompassed within the epilepsy-aphasia spectrum (EAS). The striking finding of mutations in the N-methyl-D-aspartate (NMDA) receptor subunit gene GRIN2A as the first monogenic cause in up to 20 % of patients with EAS suggests that excitatory glutamate receptors play a key role in these disorders. Patients with GRIN2A mutations have a recognizable speech and language phenotype that may assist with diagnosis. Other molecules involved in RNA binding and cell adhesion have been implicated in EAS; copy number variations are also found. The emerging picture highlights the overlap between the genetic determinants of EAS with speech and language disorders, intellectual disability, autism spectrum disorders and more complex developmental phenotypes.

JNK Inhibition Reduced Retinal Ganglion Cell Death after Ischemia/Reperfusion In Vivo and after Hypoxia In Vitro.

Mitogen-activated protein kinases (MAPKs) are key regulators that have been linked to cell survival and death. Among the main classes of MAPKs, c-jun N-terminal kinase (JNK) has been shown to mediate cell stress responses associated with apoptosis. In Vitro, hypoxia induced a significant increase in 661W cell death that paralleled increased activity of JNK and c-jun. 661W cells cultured in presence of the inhibitor of JNK (D-JNKi) were less sensitive to hypoxia-induced cell death. In vivo, elevation in intraocular pressure (IOP) in the rat promoted cell death that correlated with modulation of JNK activation. In vivo inhibition of JNK activation with D-JNKi resulted in a significant and sustained decrease in apoptosis in the ganglion cell layer, the inner nuclear layer and the photoreceptor layer. These results highlight the protective effect of D-JNKi in ischemia/reperfusion induced cell death of the retina.

Multicontrast MRI Quantification of Focal Inflammation and Degeneration in Multiple Sclerosis.

INTRODUCTION: Local microstructural pathology in multiple sclerosis patients might influence their clinical performance. This study applied multicontrast MRI to quantify inflammation and neurodegeneration in MS lesions. We explored the impact of MRI-based lesion pathology in cognition and disability. METHODS: 36 relapsing-remitting MS subjects and 18 healthy controls underwent neurological, cognitive, behavioural examinations and 3 T MRI including (i) fluid attenuated inversion recovery, double inversion recovery, and magnetization-prepared gradient echo for lesion count; (ii) T1, T2, and T2(*) relaxometry and magnetisation transfer imaging for lesion tissue characterization. Lesions were classified according to the extent of inflammation/neurodegeneration. A generalized linear model assessed the contribution of lesion groups to clinical performances. RESULTS: Four lesion groups were identified and characterized by (1) absence of significant alterations, (2) prevalent inflammation, (3) concomitant inflammation and microdegeneration, and (4) prevalent tissue loss. Groups 1, 3, 4 correlated with general disability (Adj-R (2) = 0.6; P = 0.0005), executive function (Adj-R (2) = 0.5; P = 0.004), verbal memory (Adj-R (2) = 0.4; P = 0.02), and attention (Adj-R (2) = 0.5; P = 0.002). CONCLUSION: Multicontrast MRI provides a new approach to infer in vivo histopathology of plaques. Our results support evidence that neurodegeneration is the major determinant of patients' disability and cognitive dysfunction.

A probable dual mode of action for both L- and D-lactate neuroprotection in cerebral ischemia.

Lactate has been shown to offer neuroprotection in several pathologic conditions. This beneficial effect has been attributed to its use as an alternative energy substrate. However, recent description of the expression of the HCA1 receptor for lactate in the central nervous system calls for reassessment of the mechanism by which lactate exerts its neuroprotective effects. Here, we show that HCA1 receptor expression is enhanced 24 hours after reperfusion in an middle cerebral artery occlusion stroke model, in the ischemic cortex. Interestingly, intravenous injection of L-lactate at reperfusion led to further enhancement of HCA1 receptor expression in the cortex and striatum. Using an in vitro oxygen-glucose deprivation model, we show that the HCA1 receptor agonist 3,5-dihydroxybenzoic acid reduces cell death. We also observed that D-lactate, a reputedly non-metabolizable substrate but partial HCA1 receptor agonist, also provided neuroprotection in both in vitro and in vivo ischemia models. Quite unexpectedly, we show D-lactate to be partly extracted and oxidized by the rodent brain. Finally, pyruvate offered neuroprotection in vitro whereas acetate was ineffective. Our data suggest that L- and D-lactate offer neuroprotection in ischemia most likely by acting as both an HCA1 receptor agonist for non-astrocytic (most likely neuronal) cells as well as an energy substrate.