Enhanced cerebral expression of MCT1 and MCT2 in a rat ischemia model occurs in activated microglial cells.

Monocarboxylate transporters (MCTs) are essential for the use of lactate, an energy substrate known to be overproduced in brain during an ischemic episode. The expression of MCT1 and MCT2 was investigated at 48 h of reperfusion from focal ischemia induced by unilateral extradural compression in Wistar rats. Increased MCT1 mRNA expression was detected in the injured cortex and hippocampus of compressed animals compared to sham controls. In the contralateral, uncompressed hemisphere, increases in MCT1 mRNA level in the cortex and MCT2 mRNA level in the hippocampus were noted. Interestingly, strong MCT1 and MCT2 protein expression was found in peri-lesional macrophages/microglia and in an isolectin B4+/S100beta+ cell population in the corpus callosum. In vitro, MCT1 and MCT2 protein expression was observed in the N11 microglial cell line, whereas an enhancement of MCT1 expression by tumor necrosis factor-alpha (TNF-alpha) was shown in these cells. Modulation of MCT expression in microglia suggests that these transporters may help sustain microglial functions during recovery from focal brain ischemia. Overall, our study indicates that changes in MCT expression around and also away from the ischemic area, both at the mRNA and protein levels, are a part of the metabolic adaptations taking place in the brain after ischemia.

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.

Limited role of the c-Jun N-terminal kinase pathway in a neonatal rat model of cerebral hypoxia-ischemia

D-JNKI1, a cell-permeable peptide inhibitor of the c-Jun N-terminal kinase (JNK) pathway, has been shown to be a powerful neuroprotective agent after focal cerebral ischemia in adult mice and young rats. We have investigated the potential neuroprotective effect of D-JNKI1 and the involvement of the JNK pathway in a neonatal rat model of cerebral hypoxia-ischemia. Seven-day-old rats underwent a permanent ligation of the right common carotid artery followed by 2h of hypoxia (8% oxygen). Treatment with D-JNKI1 (0.3mg/kg intraperitoneally) significantly reduced early calpain activation, late caspase-3 activation and, in the thalamus, autophagosome formation, indicating an involvement of JNK in different types of cell death: necrotic, apoptotic and autophagic. However the size of the lesion was unchanged. Further analysis showed that neonatal hypoxia-ischemia induced an immediate decrease in JNK phosphorylation (reflecting mainly P-JNK1) followed by a slow progressive increase (including P-JNK3 54kDa), whereas c-jun and c-fos expression were both strongly activated immediately after hypoxia-ischemia. In conclusion, unlike in adult ischemic models, JNK is only moderately activated after severe cerebral hypoxia-ischemia in neonatal rats and the observed positive effects of D-JNKI1 are insufficient to give neuroprotection. Thus, for perinatal asphyxia, D-JNKI1 can only be considered in association with other therapies.

Efficiency of coronary artery disease screening guidelines in asymptomatic and atypical chest pain type 2 diabetic patients

RESUME Objectifs. Évaluer la prévalence de maladie coronarienne chez les patients diabétiques de type 2 asymptomatiques ou avec angor atypique selon les recommandations américaines de l'American Diabetes Association et de l'American College of Cardiology. Méthodes. Cent cinquante-quatre patients diabétiques de type 2 asymptomatiques ou avec angor atypique et présentant au minimum 2 facteurs de risque cardio-vasculaires additionnels ont été dépistés par échocardiographie de stress (71%, n=109), scintigraphie myocardique de perfusion (26%, n=40) ou l'association des 2 examens (3%, n=5). Résultats. L'échocardiographie de stress s'est révélée positive chez 16 patients (14%) et 14 ont eu une coronarographie révélant des sténoses significatives chez 12 (86%). La scintigraphie myocardique de perfusion était positive chez 16 patients (36%). Huit patients ont eu une coronarographie et 4 (50%) présentaient des sténoses significatives. Au total, 31 patients (20%) ont montré des signes d'ischémie lors de l'examen non-invasif et 15 (10%) ont présenté des sténoses significatives à la coronarographie. Les facteurs prédictifs indépendants de la maladie coronarienne étaient le tabagisme (OR 6.5, p=0.05), la microalbuminurie (OR 3.9, p=0.03), ainsi que les souffles fémoraux (OR 17.1, p=0.008). Conclusions. En suivant les recommandations américaines, un patient sur cinq présentait une ischémie lors des examens non-invasifs, tandis que 1 sur 10 avait des sténoses significatives à la coronarographie. L'analyse multivariée suggère que des marqueurs des complications micro- et macro-vasculaires en combinaison avec des facteurs de risque cardio-vasculaire classiques pourraient améliorer le pouvoir diagnostic de ces recommandations. SUMMARY Aims. We evaluated the prevalence of coronary artery disease in asymptomatic and atypical chest pain type 2 diabetic patients according to the American Diabetes Association and American College of Cardiology guidelines. Methods. Asymptomatic or atypical chest pain type 2 diabetic patients (n=154), with at least two additional cardiovascular risk factors, were screened for coronary artery disease using stress echocardiography (71%, n=109), myocardial perfusion imaging (26%, n=40) or both (3%, n=5). Results. Stress echocardiography was positive in 16 patients (14%) and 14 had a coronary angiography, revealing significant stenoses in 12 (86%). Myocardial perfusion imaging was positive in 16 patients (36%). Eight patients underwent angiography and 4 (50%) presented significant stenoses. Overall, 31 patients (20%) demonstrated signs of ischemia on non-invasive tests and 15 (10%) presented significant stenoses on coronary angiography. Independent predictors of coronary artery disease were smoking (OR 6.5, p=0.05), microalbuminuria (OR 3.9, p=0.03) and femoral murmur (OR 17.1, p=0.008). Conclusions. Following the guidelines, one in five diabetic patient presented ischemia on noninvasive tests, while one in ten presented significant coronary stenoses. Multivariate analysis suggests that adding markers of micro- and macro-vascular complications to classical cardiovascular risk factors may enhance the diagnostic efficiency of the guidelines.

Dynamic model of the left ventricle for use in simulation of myocardial perfusion SPECT and gated SPECT

Simulation is a useful tool in cardiac SPECT to assess quantification algorithms. However, simple equation-based models are limited in their ability to simulate realistic heart motion and perfusion. We present a numerical dynamic model of the left ventricle, which allows us to simulate normal and anomalous cardiac cycles, as well as perfusion defects. Bicubic splines were fitted to a number of control points to represent endocardial and epicardial surfaces of the left ventricle. A transformation from each point on the surface to a template of activity was made to represent the myocardial perfusion. Geometry-based and patient-based simulations were performed to illustrate this model. Geometry-based simulations modeled ~1! a normal patient, ~2! a well-perfused patient with abnormal regional function, ~3! an ischaemic patient with abnormal regional function, and ~4! a patient study including tracer kinetics. Patient-based simulation consisted of a left ventricle including a realistic shape and motion obtained from a magnetic resonance study. We conclude that this model has the potential to study the influence of several physical parameters and the left ventricle contraction in myocardial perfusion SPECT and gated-SPECT studies.

Percutaneous coronary interventions prior to coronary artery bypass surgery.

BACKGROUND AND AIM OF THE STUDY: Percutaneous coronary interventions (PCI) are frequently performed before coronary artery bypass graft (CABG) surgery. This study sought to evaluate postoperative outcomes, and incidence of recurrent target ischemia in vessels with prior PCI in patients who had PCI prior to CABG compared to only CABG patients. METHODS: A review included CABG patients operated from 2000 to 2012. PCI prior to CABG patients were compared with patients having had CABG on native coronary arteries. Demographic and risk factors, including hospital morbidity, mortality, and recurrent target vessel ischemia at follow-up (FU), were compared. Major end-points were statistical differences of postoperative morbidity and reintervention rates due to symptomatic graft failure or target vessel ischemia during FU. RESULTS: Twenty-four percent of 1669 isolated CABG patients had PCI prior to CABG, with an increasing percentage during recent years. Demographics, risk factors, comorbidities and mortality rates were similar. Incidence of postoperative hemorrhage (OR 1.9; 95% CI 1.1-3.2; p = 0.02), perioperative myocardial infarction rate (p = 0.02), neurological deficits (OR 3.5; 95% CI 1.2-9.7; p = 0.02) and re-intervention rate for symptomatic graft or target vessel occlusion were higher in pretreated patients (OR 1.8; 95% CI 1.1-3.0; p = 0.01). CONCLUSIONS: PCI prior to CABG increases the risk for postoperative morbidity. Increased postoperative hemorrhage could be attributed to ongoing double anti-platelet therapy. doi: 10.1111/jocs.12514 (J Card Surg 2015;30:313-318).

Genome-wide profiling of the cardiac transcriptome after myocardial infarction identifies novel heart-specific long non-coding RNAs.

AIM: Heart disease is recognized as a consequence of dysregulation of cardiac gene regulatory networks. Previously, unappreciated components of such networks are the long non-coding RNAs (lncRNAs). Their roles in the heart remain to be elucidated. Thus, this study aimed to systematically characterize the cardiac long non-coding transcriptome post-myocardial infarction and to elucidate their potential roles in cardiac homoeostasis. METHODS AND RESULTS: We annotated the mouse transcriptome after myocardial infarction via RNA sequencing and ab initio transcript reconstruction, and integrated genome-wide approaches to associate specific lncRNAs with developmental processes and physiological parameters. Expression of specific lncRNAs strongly correlated with defined parameters of cardiac dimensions and function. Using chromatin maps to infer lncRNA function, we identified many with potential roles in cardiogenesis and pathological remodelling. The vast majority was associated with active cardiac-specific enhancers. Importantly, oligonucleotide-mediated knockdown implicated novel lncRNAs in controlling expression of key regulatory proteins involved in cardiogenesis. Finally, we identified hundreds of human orthologues and demonstrate that particular candidates were differentially modulated in human heart disease. CONCLUSION: These findings reveal hundreds of novel heart-specific lncRNAs with unique regulatory and functional characteristics relevant to maladaptive remodelling, cardiac function and possibly cardiac regeneration. This new class of molecules represents potential therapeutic targets for cardiac disease. Furthermore, their exquisite correlation with cardiac physiology renders them attractive candidate biomarkers to be used in the clinic.

A hypoxic episode during cardiogenesis downregulates the adenosinergic system and alters the myocardial anoxic tolerance.

To what extent hypoxia alters the adenosine (ADO) system and impacts on cardiac function during embryogenesis is not known. Ectonucleoside triphosphate diphosphohydrolase (CD39), ecto-5'-nucleotidase (CD73), adenosine kinase (AdK), adenosine deaminase (ADA), equilibrative (ENT1,3,4), and concentrative (CNT3) transporters and ADO receptors A1, A2A, A2B, and A3 constitute the adenosinergic system. During the first 4 days of development chick embryos were exposed in ovo to normoxia followed or not followed by 6 h hypoxia. ADO and glycogen content and mRNA expression of the genes were determined in the atria, ventricle, and outflow tract of the normoxic (N) and hypoxic (H) hearts. Electrocardiogram and ventricular shortening of the N and H hearts were recorded ex vivo throughout anoxia/reoxygenation ± ADO. Under basal conditions, CD39, CD73, ADK, ADA, ENT1,3,4, CNT3, and ADO receptors were differentially expressed in the atria, ventricle, and outflow tract. In H hearts ADO level doubled, glycogen decreased, and mRNA expression of all the investigated genes was downregulated by hypoxia, except for A2A and A3 receptors. The most rapid and marked downregulation was found for ADA in atria. H hearts were arrhythmic and more vulnerable to anoxia-reoxygenation than N hearts. Despite downregulation of the genes, exposure of isolated hearts to ADO 1) preserved glycogen through activation of A1 receptor and Akt-GSK3β-GS pathway, 2) prolonged activity and improved conduction under anoxia, and 3) restored QT interval in H hearts. Thus hypoxia-induced downregulation of the adenosinergic system can be regarded as a coping response, limiting the detrimental accumulation of ADO without interfering with ADO signaling.

Pontages veineux in situ. Indications, technique et résultats. A propos d'une étude prospective de 26 cas consécutifs [In situ venous grafts. Indications, technique and results. Prospective study of 26 consecutive cases].

The in situ saphenous vein bypass has been introduced in our department since 1989. A total of 26 bypasses in 22 patients have been followed prospectively. Indications for revascularisation have been severe arterial insufficiency in 73% of the cases (stage III or IV). With the exception of one postoperative death (myocardial infarction), all the patients have recovered uneventfully, with a regression to stage I. No amputation has been necessary. Morbidity has been 30%, with mainly minor local complications. The primary patency rate is 83% at one year and 78% after 2 and 3 years, whereas the secondary patency rate is 91% at one year, and remains constant thereafter up to 3 years. Considering our results and those from the literature, we believe that the in situ technique is very valuable, especially for below-knee vascular reconstruction. Technical difficulties of the method are analysed.

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.

Toll-like receptor 5 deficiency exacerbates cardiac injury and inflammation induced by myocardial ischaemia-reperfusion in the mouse.

Myocardial ischaemia-reperfusion (MIR) triggers a sterile inflammatory response important for myocardial healing, but which may also contribute to adverse ventricular remodelling. Such inflammation is initiated by molecular danger signals released by damaged myocardium, which induce innate immune responses by activating toll-like receptors (TLRs). Detrimental roles have been recently reported for TLR2, TLR3 and TLR4. The role of other TLRs is unknown. We therefore evaluated the role of TLR5, expressed at high level in the heart, in the development of myocardial damage and inflammation acutely triggered by MIR. TLR5-/- and wild-type (WT) mice were exposed to MIR (30 min ischaemia, 2 h reperfusion). We measured infarct size, markers of cardiac oxidative stress, myocardial phosphorylation state of mitogen-activated protein (MAP) kinases and AKT, expression levels of chemokines and cytokines in the heart and plasma, as well as cardiac function by echography and conductance volumetry. TLR5-deficient mice had normal cardiac morphology and function under physiological conditions. After MIR, the absence of TLR5 promoted an increase in infarct size and myocardial oxidative stress. Lack of TLR5 fostered p38 phosphorylation, reduced AKT phosphorylation and markedly increased the expression of inflammatory cytokines, whereas it precipitated acute LV (left ventricle) dysfunction. Therefore, contrary to the detrimental roles of TLR2, TLR3 and TLR4 in the infarcted heart, TLR5 is important to limit myocardial damage, inflammation and functional compromise after MIR.

Bivalirudin for patients with acute coronary syndromes

Background: Current guidelines for patients with moderate- or high-risk acute coronary syndromes recommend an early invasive approach with concomitant antithrombotic therapy, including aspirin, clopidogrel, unfractionated or low-molecular-weight heparin, and glycoprotein IIb/IIIa inhibitors. We evaluated the role of thrombin-specific anticoagulation with bivalirudin in such patients. Methods: We assigned 13,819 patients with acute coronary syndromes to one of three antithrombotic regimens: unfractionated heparin or enoxaparin plus a glycoprotein IIb/IIIa inhibitor, bivalirudin plus a glycoprotein IIb/IIIa inhibitor, or bivalirudin alone. The primary end points were a composite ischemia end point (death, myocardial infarction, or unplanned revascularization for ischemia), major bleeding, and the net clinical outcome, defined as the combination of composite ischemia or major bleeding. Results: Bivalirudin plus a glycoprotein IIb/IIIa inhibitor, as compared with heparin plus a glycoprotein IIb/IIIa inhibitor, was associated with noninferior 30-day rates of the composite ischemia end point (7.7% and 7.3%, respectively), major bleeding (5.3% and 5.7%), and the net clinical outcome end point (11.8% and 11.7%). Bivalirudin alone, as compared with heparin plus a glycoprotein IIb/IIIa inhibitor, was associated with a noninferior rate of the composite ischemia end point (7.8% and 7.3%, respectively; P = 0.32; relative risk, 1.08; 95% confidence interval [CI], 0.93 to 1.24) and significantly reduced rates of major bleeding (3.0% vs. 5.7%; P<0.001; relative risk, 0.53; 95% CI, 0.43 to 0.65) and the net clinical outcome end point (10.1% vs. 11.7%; P = 0.02; relative risk, 0.86; 95% CI, 0.77 to 0.97). Conclusions: In patients with moderate- or high-risk acute coronary syndromes who were undergoing invasive treatment with glycoprotein IIb/IIIa inhibitors, bivalirudin was associated with rates of ischemia and bleeding that were similar to those with heparin. Bivalirudin alone was associated with similar rates of ischemia and significantly lower rates of bleeding. (ClinicalTrials.gov number, NCT00093158.)