Clusterin in neurological disorders: molecular perspectives and clinical relevance.

Firstly discovered in rete testis fluid, clusterin is a glycoprotein present in most of the other biological fluids. Several isoforms of clusterin are encoded from a single gene located on chromosome 8 in human species. Among the different isoforms, the secreted form of clusterin is expressed by a variety of tissues, including the nervous system under normal conditions. This form is presumed to play an anti-apoptotic role and seems to be a major determinant in cell survival and neuroplasticity after stroke. In animal models of this pathology, both neuronal and astroglial subpopulations express high levels of clusterin early after the ischemic damage. Recent lines of evidence point also to its possible involvement in neurodegenerative disorders. It is thought that in Alzheimer's disease the association between amyloidogenic peptides and clusterin contributes to limit Aβ species misfolding and facilitates their clearance from the extracellular space. Thus, intercellular and intracellular factors that modulate local clusterin expression in the nervous system may represent potent targets for neurodegenerative disease therapies. In this review we provide a critical overview of the most recent data on the involvement of clusterin in neurodegenerative diseases with special reference to their putative clinical relevance.

Hypoxie-ischémie cérébrale néonatale : rôle de la voie de JNK et implication de l'autophagie dans la mort neuronale

Résumé : Malgré les immenses progrès réalisés depuis plusieurs années en médecine obstétricale ainsi qu'en réanimation néonatale et en recherche expérimentale, l'asphyxie périnatale, une situation de manque d'oxygène autour du moment de la naissance, reste une cause majeure de mortalité et de morbidité neurologique à long terme chez l'enfant (retard mental, paralysie cérébrale, épilepsie, problèmes d'apprentissages) sans toutefois de traitement pharmacologique réel. La nécessité de développer de nouvelles stratégies thérapeutiques pour les complications de l'asphyxie périnatale est donc aujourd'hui encore essentielle. Le but général de ce travail est l'identification de nouvelles cibles thérapeutiques impliquées dans des mécanismes moléculaires pathologiques induits par l'hypoxie-ischémie (HI) dans le cerveau immature. Pour cela, le modèle d'asphyxie périnatale (proche du terme) le plus reconnu chez le rongeur a été développé (modèle de Rice et Vannucci). Il consiste en la ligature permanente d'une artère carotide commune (ischémie) chez le raton de 7 jours combinée à une période d'hypoxie à 8% d'oxygène. Il permet ainsi d'étudier les lésions de type hypoxique-ischémique dans différentes régions cérébrales dont le cortex, l'hippocampe, le striatum et le thalamus. La première partie de ce travail a abordé le rôle de deux voies de MAPK, JNK et p38, après HI néonatale chez le raton à l'aide de peptides inhibiteurs. Tout d'abord, nous avons démontré que D-JNKI1, un peptide inhibiteur de la voie de JNK présentant de fortes propriétés neuroprotectrices dans des modèles d'ischémie cérébrale adulte ainsi que chez le jeune raton, peut intervenir sur différentes voies de mort dont l'activation des calpaïnes (marqueur de la nécrose précoce), l'activation de la caspase-3 (marqueur de l'apoptose) et l'expression de LC3-II (marqueur de macroautophagie). Malgré ces effets positifs le traitement au D-JNKI1 ne modifie pas l'étendue de la lésion cérébrale. L'action limitée de D-JNKI1 peut s'expliquer par une implication modérée des JNKs (faiblement activées et principalement l'isotype JNK3) après HI néonatale sévère. Au contraire, l'inhibition de la voie de nNOS/p38 par le peptide DTAT-GESV permet une augmentation de 20% du volume du tissu sain à court et long terme. Le second projet a étudié les effets de l'HI néonatale sur l'autophagie neuronale. En effet, l'autophagie est un processus catabolique essentiel au bien-être de la cellule. Le type principal d'autophagie (« macroautophagie » , que nous appellerons par la suite « autophagie ») consiste en la séquestration d'éléments à dégrader (protéines ou organelles déficients) dans un compartiment spécialisé, l'autophagosome, qui fusionne avec un lysosome pour former un autolysosome où le contenu est dégradé par les hydrolases lysosomales. Depuis peu, l'excès ou la dérégulation de l'autoptiagie a pu être impliqué dans la mort cellulaire en certaines conditions de stress. Ce travail démontre que l'HI néonatale chez le raton active fortement le flux autophagique, c'est-à-dire augmente la formation des autophagosomes et des autolysosomes, dans les neurones en souffrance. De plus, la relation entre l'autophagie et l'apoptose varie selon la région cérébrale. En effet, alors que dans le cortex les neurones en voie de mort présentent des caractéristiques mixtes apoptotiques et autophagiques, ceux du CA3 sont essentiellement autophagiques et ceux du CA1 sont principalement apoptotiques. L'induction de l'autophagie après HI néonatale semble donc participer à la mort neuronale soit par l'enclenchement de l'apoptose soit comme mécanisme de mort en soi. Afin de comprendre la relation pouvant exister entre autophagie et apoptase un troisième projet a été réalisé sur des cultures primaires de neurones corticaux exposés à un stimulus apoptotique classique, la staurosporine (STS). Nous avons démontré que l'apoptose induite par la STS était précédée et accompagnée par une forte activation du flux autophagique neuronal. L'inhibition de l'autophagie de manière pharmacologique (3-MA) ou plus spécifiquement par ARNs d'interférence dirigés contre deux protéines autophagiques importantes (Atg7 et Atg5) a permis de mettre en évidence des rôles multiples de l'autophagie dans la mort neuronale. En effet, l'autophagie prend non seulement part à une voie de mort parallèle à l'apoptose pouvant être impliquée dans l'activation des calpaïnes, mais est également partiellement responsable de l'induction des voies apoptotiques (activation de la caspase-3 et translocation nucléaire d'AIF). En conclusion, ce travail a montré que l'inhibition de JNK par D-JNKI1 n'est pas un outil neuroprotecteur efficace pour diminuer la mort neuronale provoquée par l'asphyxie périnatalé sévère, et met en lumière deux autres voies thérapeutiques beaucoup plus prometteuses, l'inhibition de nNOS/p38 ou de l'autophagie. ABSTRACT : Despite enormous progress over the last«decades in obstetrical and neonatal medicine and experimental research, perinatal asphyxia, a situation of lack of oxygen around the time of the birth, remains a major cause of mortality and long term neurological morbidity in children (mental retardation, cerebral palsy, epilepsy, learning difficulties) without any effective treatment. It is therefore essential to develop new therapeutic strategies for the complications of perinatal asphyxia. The overall aim of this work was to identify new therapeutic targets involved in pathological molecular mechanisms induced by hypoxia-ischemia (HI) in the immature brain. For this purpose, the most relevant model of perinatal asphyxia (near term) in rodents has been developed (model of Rice and Vannucci). It consists in the permanent ligation of one common carotid artery (ischemia) in the 7-day-old rat combined with a period of hypoxia at 8% oxygen. This model allows the study of the hypoxic-ischemic lesion in different brain regions including the cortex, hippocampus, striatum and thalamus. The first part of this work addressed the role of two MAPK pathways (JNK and p38) after rat neonatal HI using inhibitory peptides. First, we demonstrated that D-JNKI1, a JNK peptide inhibitor presenting strong neuroprotective properties in models of cerebral ischemia in adult and young rats, could affect different cell death mechanisms including the activation of calpain (a marker of necrosis) and caspase-3 (a marker of apoptosis), and the expression of LC3-II (a marker of macroautophagy). Despite these positive effects, D-JNKI1 did not modify the extent of brain damage. The limited action of D-JNKI1 can be explained by the fact that JNKs were only moderately involved (weakly activated and principally the JNK3 isotype) after severe neonatal HI. In contrast, inhibition of nNOS/p38 by the peptide D-TAT-GESV increased the surviving tissue volume by around 20% at short and long term. The second project investigated the effects of neonatal HI on neuronal autophagy. Indeed, autophagy is a catabolic process essential to the well-being of the cell. The principal type of autophagy ("macroautophagy", that we shall henceforth call "autophagy") involves the sequestration of elements to be degraded (deficient proteins or organelles) in a specialized compartment, the autophagosome, which fuses with a lysosome to form an autolysosome where the content is degraded by lysosomal hydrolases. Recently, an excess or deregulation of autophagy has been implicated in cell death in some stress conditions. The present study demonstrated that rat neonatal HI highly enhanced autophagic flux, i.e. increased autophagosome and autolysosome formation, in stressed neurons. Moreover, the relationship between autophagy and apoptosis varies according to the brain region. Indeed, whereas dying neurons in the cortex exhibited mixed features of apoptosis and autophagy, those in CA3 were primarily autophagíc and those in CA1 were mainly apoptotic. The induction of autophagy after neonatal HI seems to participate in neuronal death either by triggering apoptosis or as a death mechanism per se. To understand the relationships that may exist between autophagy and apoptosis, a third project has been conducted using primary cortical neuronal cultures exposed to a classical apoptotic stimulus, staurosporine (STS). We demonstrated that STS-induced apoptosis was preceded and accompanied by a strong activation of neuronal autophagic flux. Inhibition of autophagy pharmacologically (3-MA) or more specifically by RNA interference directed against two important autophagic proteins (Atg7 and AtgS) showed multiple roles of autophagy in neuronal death. Indeed, autophagy was not only involved in a death pathway parallel to apoptosis possibly involved in the activation of calpains, but was also partially responsible for the induction of apoptotic pathways (caspase-3 activation and AIF nuclear translocation). In conclusion, this study showed that JNK inhibition by D-JNKI1 is not an effective neuroprotective tool for decreasing neuronal death following severe perinatal asphyxia, but highlighted two more promising therapeutic approaches, inhibition of the nNOSlp38 pathway or of autophagy.

Floating arterial thrombus related stroke treated by intravenous thrombolysis.

BACKGROUND: The effects of intravenous thrombolysis on floating thrombi in cervical and intracranial arteries of acute ischemic stroke patients are unknown. Similarly, the best prevention methods of early recurrences remain controversial. This study aimed to describe the clinical and radiological outcome of thrombolyzed strokes with floating thrombi. METHODS: We retrospectively analyzed all thrombolyzed stroke patients in our institution between 2003 and 2010 with floating thrombi on acute CT-angiography before the intravenous thrombolysis. The floating thrombus was diagnosed if an elongated thrombus of at least 5 mm length, completely surrounded by contrast on supra-aortic neck or intracerebral arteries, was present on CT-angiography. Demographics, vascular risk factors, and comorbidities were recorded and stroke etiology was determined after a standardized workup. Repeat arterial imaging was performed by CTA at 24 h or before if clinical worsening was noted and then by Doppler and MRA during the first week and at four months. RESULTS: Of 409 thrombolyzed stroke patients undergoing acute CT Angiography, seven (1.7%) had a floating thrombus; of these seven, six had it in the anterior circulation. Demographics, risk factors and stroke severity of these patients were comparable to the other thrombolyzed patients. After intravenous thrombolysis, the floating thrombi resolved completely at 24 h in four of the patients, whereas one had an early recurrent stroke and one developed progressive worsening. One patient developed early occlusion of the carotid artery with floating thrombus and subsequently a TIA. The two patients with a stable floating thrombus had no clinical recurrences. In the literature, only one of four reported cases were found to have a thrombolysis-related early recurrence. CONCLUSIONS: Long-term outcome seemed similar in thrombolyzed patients with floating thrombus, despite a possible increase of very early recurrence. It remains to be established whether acute mechanical thrombectomy could be a safer and more effective treatment to prevent early recurrence. However, intravenous thrombolysis should not be withheld in eligible stroke patients.

Neuroprotection by inhibiting the c-Jun N-terminal kinase pathway after cerebral ischemia occurs independently of interleukin-6 and keratinocyte-derived chemokine (KC/CXCL1) secretion.

BACKGROUND: Cerebral ischemia is associated with the activation of glial cells, infiltration of leukocytes and an increase in inflammatory mediators in the ischemic brain and systemic circulation. How this inflammatory response influences lesion size and neurological outcome remains unclear. D-JNKI1, an inhibitor of the c-Jun N-terminal kinase pathway, is strongly neuroprotective in animal models of stroke. Intriguingly, the protection mediated by D-JNKI1 is high even with intravenous administration at very low doses with undetectable drug levels in the brain, pointing to a systemic mode of action, perhaps on inflammation. FINDINGS: We evaluated whether D-JNKI1, administered intravenously 3 h after the onset of middle cerebral artery occlusion (MCAO), modulates secretion of the inflammatory mediators interleukin-6 and keratinocyte-derived chemokine in the plasma and from the spleen and brain at several time points after MCAO. We found an early release of both mediators in the systemic circulation followed by an increase in the brain and went on to show a later systemic increase in vehicle-treated mice. Release of interleukin-6 and keratinocyte-derived chemokine from the spleen of mice with MCAO was not significantly different from sham mice. Interestingly, the secretion of these inflammatory mediators was not altered in the systemic circulation or brain after successful neuroprotection with D-JNKI1. CONCLUSIONS: We demonstrate that neuroprotection with D-JNKI1 after experimental cerebral ischemia is independent of systemic and brain release of interleukin-6 and keratinocyte-derived chemokine. Furthermore, our findings suggest that the early systemic release of interleukin-6 and keratinocyte-derived chemokine may not necessarily predict an unfavorable outcome in this model.

Myocardial infarct size and mortality depend on the time of day-a large multicenter study.

BACKGROUND: Different studies have shown circadian variation of ischemic burden among patients with ST-Elevation Myocardial Infarction (STEMI), but with controversial results. The aim of this study was to analyze circadian variation of myocardial infarction size and in-hospital mortality in a large multicenter registry. METHODS: This retrospective, registry-based study was based on data from AMIS Plus, a large multicenter Swiss registry of patients who suffered myocardial infarction between 1999 and 2013. Peak creatine kinase (CK) was used as a proxy measure for myocardial infarction size. Associations between peak CK, in-hospital mortality, and the time of day at symptom onset were modelled using polynomial-harmonic regression methods. RESULTS: 6,223 STEMI patients were admitted to 82 acute-care hospitals in Switzerland and treated with primary angioplasty within six hours of symptom onset. Only the 24-hour harmonic was significantly associated with peak CK (p = 0.0001). The maximum average peak CK value (2,315 U/L) was for patients with symptom onset at 23:00, whereas the minimum average (2,017 U/L) was for onset at 11:00. The amplitude of variation was 298 U/L. In addition, no correlation was observed between ischemic time and circadian peak CK variation. Of the 6,223 patients, 223 (3.58%) died during index hospitalization. Remarkably, only the 24-hour harmonic was significantly associated with in-hospital mortality. The risk of death from STEMI was highest for patients with symptom onset at 00:00 and lowest for those with onset at 12:00. DISCUSSION: As a part of this first large study of STEMI patients treated with primary angioplasty in Swiss hospitals, investigations confirmed a circadian pattern to both peak CK and in-hospital mortality which were independent of total ischemic time. Accordingly, this study proposes that symptom onset time be incorporated as a prognosis factor in patients with myocardial infarction.

Influence of the timing of cardiac surgery on the outcome of patients with infective endocarditis and stroke.

BACKGROUND: The timing of cardiac surgery after stroke in infective endocarditis (IE) remains controversial. We examined the relationship between the timing of surgery after stroke and the incidence of in-hospital and 1-year mortalities. METHODS: Data were obtained from the International Collaboration on Endocarditis-Prospective Cohort Study of 4794 patients with definite IE who were admitted to 64 centers from June 2000 through December 2006. Multivariate logistic regression and Cox regression analyses were performed to estimate the impact of early surgery on hospital and 1-year mortality after adjustments for other significant covariates. RESULTS: Of the 857 patients with IE complicated by ischemic stroke syndromes, 198 who underwent valve replacement surgery poststroke were available for analysis. Overall, 58 (29.3%) patients underwent early surgical treatment vs 140 (70.7%) patients who underwent late surgical treatment. After adjustment for other risk factors, early surgery was not significantly associated with increased in-hospital mortality rates (odds ratio, 2.308; 95% confidence interval [CI], .942-5.652). Overall, probability of death after 1-year follow-up did not differ between 2 treatment groups (27.1% in early surgery and 19.2% in late surgery group, P = .328; adjusted hazard ratio, 1.138; 95% CI, .802-1.650). CONCLUSIONS: There is no apparent survival benefit in delaying surgery when indicated in IE patients after ischemic stroke. Further observational analyses that include detailed pre- and postoperative clinical neurologic findings and advanced imaging data (eg, ischemic stroke size), may allow for more refined recommendations on the optimal timing of valvular surgery in patients with IE and recent stroke syndromes.

Leadership in cardiac surgery.

Despite the efficacy of cardiac surgery, less invasive interventions with more uncertain long-term outcomes are increasingly challenging surgery as first-line treatment for several congenital, degenerative and ischemic cardiac diseases. The specialty must evolve if it is to ensure its future relevance. More importantly, it must evolve to ensure that future patients have access to treatments with proven long-term effectiveness. This cannot be achieved without dynamic leadership; however, our contention is that this is not enough. The demands of a modern surgical career and the importance of the task at hand are such that the serendipitous emergence of traditional charismatic leadership cannot be relied upon to deliver necessary change. We advocate systematic analysis and strategic leadership at a local, national and international level in four key areas: Clinical Care, Research, Education and Training, and Stakeholder Engagement. While we anticipate that exceptional individuals will continue to shape the future of our specialty, the creation of robust structures to deliver collective leadership in these key areas is of paramount importance.

Severe stroke: patient profile and predictors of favorable outcome.

Summary.  Background:  Severe stroke carries high rates of mortality and morbidity. The aims of this study were to determine the characteristics of patients who initially presented with severe ischemic stroke, and to identify acute and subacute predictors of favorable clinical outcome in these patients. Methods:  An observational cohort study, Acute Stroke Registry and Analysis of Lausanne (ASTRAL), was analyzed, and all patients presenting with severe stroke - defined as a National Institute of Health Stroke Scale score of ≥ 20 on admission - were compared with all other patients. In a multivariate analysis, associations with demographic, clinical, pathophysiologic, metabolic and neuroimaging factors were determined. Furthermore, we analyzed predictors of favorable outcome (modified Rankin scale score of ≤ 3 at 3 months) in the subgroup of severe stroke patients. Results:  Of 1915 consecutive patients, 243 (12.7%) presented with severe stroke. This was significantly associated with cardio-embolic stroke mechanism (odds ratio [OR] 1.74, 95% confidence interval [CI] 1.19-2.54), unknown stroke onset (OR 2.35, 95% CI 1.14-4.83), more neuroimaging signs of early ischemia (mostly computed tomography; OR 2.65, 95% CI 1.79-3.92), arterial occlusions on acute imaging (OR 27.01, 95% CI 11.5-62.9), fewer chronic radiologic infarcts (OR 0.43, 95% CI 0.26-0.72), lower hemoglobin concentration (OR 0.97, 95% CI 0.96-0.99), and higher white cell count (OR 1.05, 95% CI 1.00-1.11). In the 68 (28%) patients with favorable outcomes despite presenting with severe stroke, this was predicted by lower age (OR 0.94, 95% CI 0.92-0.97), preceding cerebrovascular events (OR 3.00, 95% CI 1.01-8.97), hypolipemic pretreatment (OR 3.82, 95% CI 1.34-10.90), lower acute temperature (OR 0.43, 95% CI 0.23-0.78), lower subacute glucose concentration (OR 0.74, 95% CI 0.56-0.97), and spontaneous or treatment-induced recanalization (OR 4.51, 95% CI 1.96-10.41). Conclusions:  Severe stroke presentation is predicted by multiple clinical, radiologic and metabolic variables, several of which are modifiable. Predictors in the 28% of patients with favorable outcome despite presenting with severe stroke include hypolipemic pretreatment, lower acute temperature, lower glucose levels at 24 h, and arterial recanalization.

Postmortem imaging of sudden cardiac death

Postmortem imaging is increasingly used in forensic practice in cases of natural deaths related to cardiovascular diseases, which represent the most common causes of death in developed countries. While radiological examination is generally considered to be a good complement for conventional autopsy, it was thought to have limited application in cardiovascular pathology. At present, multidetector computed tomography (MDCT), CT angiography, and cardiac magnetic resonance imaging (MRI) are used in postmortem radiological investigation of cardiovascular pathologies. This review presents the actual state of postmortem imaging for cardiovascular pathologies in cases of sudden cardiac death (SCD), taking into consideration both the advantages and limitations. The radiological evaluation of ischemic heart disease (IHD), the most frequent cause of SCD in the general population of industrialized countries, includes the examination of the coronary arteries and myocardium. Postmortem CT angiography (PMCTA) is very useful for the detection of stenoses and occlusions of coronary arteries but less so for the identification of ischemic myocardium. MRI is the method of choice for the radiological investigation of the myocardium in clinical practice, but its accessibility and application are still limited in postmortem practice. There are very few reports implicating postmortem radiology in the investigation of other causes of SCD, such as cardiomyopathies, coronary artery abnormalities, and valvular pathologies. Cardiomyopathies representing the most frequent cause of SCD in young athletes cannot be diagnosed by echocardiography, the most widely available technique in clinical practice for the functional evaluation of the heart and the detection of cardiomyopathies. PMCTA and MRI have the potential to detect advanced stages of diseases when morphological substrate is present, but these methods have yet to be sufficiently validated for postmortem cases. Genetically determined channelopathies cannot be detected radiologically. This review underlines the need to establish the role of postmortem radiology in the diagnosis of SCD.

The C-Jun N-Terminal Kinase Inhibition in Intracerebral Hemorrhage

Background: In intracerebral hemorrhage (ICH), a subtype of stroke, the bloodentry into the brain triggers toxicity resulting in a strong loss of neurons andinflammation. Water content is also increases leading to growing intracranial pressure,which worsens neurological outcome. C-Jun N-terminal kinases (JNKs) areactivated in response to stress stimuli. Specific inhibition of JNK by a TAT-coupledpeptide (XG-102) mediates neuroprotection in several models of ischemic stroke.Recently, we have noted that the JNK pathway is also activated in a mouse modelof ICH, raising the question of the efficacy of XG-102 in this model.Method: ICH was induced in the mouse by intrastriatal injection of bacterialcollagenase (0,1U). Three hours later, animals received an i.v. injection of XG-102(100μg/kg). The neuroscore was assessed using a scale (from 0 to 9) based on 3behavioral tests performed daily. Then, mice were sacrificed at 6h, 24h, 48h and 5dafter ICH and histological studies performed.Results: XG-102 significantly improves neurological outcome at 24h (mean score:1,8±1.4 vs 3,4±1.8, p<0.01). Analysis of the lesion volume revealed a significantdecrease of the lesion area in the treated group at 48h (29±11 mm3 vs 39±5 mm3,p = 0.04). XG-102 mainly inhibits the edema component of the lesion. Indeed, asignificant decrease of the brain swelling was observed in treated animals at 48h(14±13% vs 26±9%, p=0.04) and 5d (-0,3±4.5% vs 5,1±3.6%, p=0.01).Conclusions: Inhibition of the JNK pathway by XG-102 appears to lead to asignificant decrease of the cerebral edema in the ICH model providing a furtherbeneficial effect of the XG-102 treatment. This result is of interest becausecurrently, clinical treatment for brain edema is limited. Importantly, the beneficialeffects observed with XG-102 in both stroke models open the possibility to rapidlytreat patients before identifying the stroke subtype by imaging.

Protonation controls ASIC1a activity via coordinated movements in multiple domains.

Acid-sensing ion channels (ASICs) are neuronal Na(+)-conducting channels activated by extracellular acidification. ASICs are involved in pain sensation, expression of fear, and neurodegeneration after ischemic stroke. Functional ASICs are composed of three identical or homologous subunits, whose extracellular part has a handlike structure. Currently, it is unclear how protonation of residues in extracellular domains controls ASIC activity. Knowledge of these mechanisms would allow a rational development of drugs acting on ASICs. Protonation may induce conformational changes that control the position of the channel gate. We used voltage-clamp fluorometry with fluorophores attached to residues in different domains of ASIC1a to detect conformational changes. Comparison of the timing of fluorescence and current signals identified residues involved in movements that preceded desensitization and may therefore be associated with channel opening or early steps leading to desensitization. Other residues participated in movements intimately linked to desensitization and recovery from desensitization. Fluorescence signals of all mutants were detected at more alkaline pH than ionic currents. Their midpoint of pH dependence was close to that of steady-state desensitization, whereas the steepness of the pH fluorescence relationship was closer to that of current activation. A sequence of movements was observed upon acidification, and its backward movements during recovery from desensitization occurred in the reverse order, indicating that the individual steps are interdependent. Furthermore, the fluorescence signal of some labeled residues in the finger domain was strongly quenched by a Trp residue in the neighboring β-ball domain. Upon channel activation, their fluorescence intensity increased, indicating that the finger moved away from the β ball. This extensive analysis of activity-dependent conformational changes in ASICs sheds new light on the mechanisms by which protonation controls ASIC activity.

Non-invasive diagnostic biomarkers for estimating the onset time of permanent cerebral ischemia.

The treatments for ischemic stroke can only be administered in a narrow time-window. However, the ischemia onset time is unknown in ~30% of stroke patients (wake-up strokes). The objective of this study was to determine whether MR spectra of ischemic brains might allow the precise estimation of cerebral ischemia onset time. We modeled ischemic stroke in male ICR-CD1 mice using a permanent middle cerebral artery filament occlusion model with laser Doppler control of the regional cerebral blood flow. Mice were then subjected to repeated MRS measurements of ipsilateral striatum at 14.1 T. A striking initial increase in γ-aminobutyric acid (GABA) and no increase in glutamine were observed. A steady decline was observed for taurine (Tau), N-acetyl-aspartate (NAA) and similarly for the sum of NAA+Tau+glutamate that mimicked an exponential function. The estimation of the time of onset of permanent ischemia within 6 hours in a blinded experiment with mice showed an accuracy of 33±10 minutes. A plot of GABA, Tau, and neuronal marker concentrations against the ratio of acetate/NAA allowed precise separation of mice whose ischemia onset lay within arbitrarily chosen time-windows. We conclude that (1)H-MRS has the potential to detect the clinically relevant time of onset of ischemic stroke.

Intravenous thrombolysis in patients with stroke attributable to small artery occlusion.

BACKGROUND: Intravenous thrombolysis (IVT) for stroke seems to be beneficial independent of the underlying etiology. Recent observations raised concern that IVT might cause harm in patients with strokes attributable to small artery occlusion (SAO). OBJECTIVE: The safety of IVT in SAO-patients is addressed in this study. METHODS: We used the Swiss IVT databank to compare outcome and complications of IVT-treated SAO-patients with IVT-treated patients with other etiologies (non-SAO-patients). Main outcome and complication measures were independence (modified Rankin scale <or=2) at 3 months, intracranial hemorrhage (ICH), and recurrent ischaemic stroke. RESULTS: Sixty-five (6.2%) of 1048 IVT-treated patients had SAO. Amongst SAO-patients, 1.5% (1/65) patients died, compared to 11.2% (110/983) in the non-SAO-group (P = 0.014). SAO-patients reached independence more often than non-SAO-patients (75.4% versus 58.9%; OR 2.14 (95% CI 1.20-3.81; P = 0.001). This association became insignificant after adjustment for age, gender, and stroke severity (OR 1.41 95% CI 0.713-2.788; P = 0.32). Glucose level and (to some degree) stroke severity but not age predicted 3-month-independence in IVT-treated SAO-patients. ICHs (all/symptomatic) were similar in SAO- (12.3%/4.6%) and non-SAO-patients (13.4%/5.3%; P > 0.8). Fatal ICH occurred in 3.3% of the non-SAO-patients but none amongst SAO-patients. Ischaemic stroke within 3 months after IVT reoccurred in 1.5% of SAO-patients and in 2.3% of non-SAO-patients (P = 0.68). CONCLUSION: IVT-treated SAO-patients died less often and reached independence more often than IVT-treated non-SAO-patients. However, the variable 'SAO' was a dependent rather than an independent outcome predictor. The absence of an excess in ICH indicates that IVT seems not to be harmful in SAO-patients.

Artificial Urinary Sphincter based on smart materials

Objective: There are only a few established artificial urinary sphincters for treatment of incontinence. We have developed a new device composed by three parts: the actuator, three contractile rings and a control unit. The actuator is made of Nitinol fibers, driven by microprocessor. The fibers are linked to the rings placed around the urethra. They function with alternance in their open and closed position. This concept is called piano concept. With this set-up, the constant compression on the urethra is strongly reduced. Methods: Six male sheep have been used for this study. The sphincter was open each hour for a period of 10 min., to guaranty urination. The bladder was filled with water while one cuff was closed and bladder pressure was monitored. The animals were sacrificed. Two biopsies around two cuffs of each explant and all three cuffs from each explant including urethra were analyzed. Urethra not surrounded by a cuff was taken as control. Results: The pressure exerted by the sphincter around the urethra provided continence. Simulated incontinence occurred at a pressure of 1bar measured on the bladder wall using a pressure probe. The closing force of the cuff was approx. 0·7N. No difference in tissue structure and organization of the urethra with and without artificial sphincter was observed. Conclusions: This device has several advantages compared to other urinary sphincters. It is easy to implant, has no hydraulic nature and reduces ischemic injury of the urethra by the alternance of urethral part compressed. Proof of concept in vivo has been demonstrated. Other studies are planned to determine long-term outcome.

Predicting stroke through genetic risk functions: the CHARGE Risk Score Project.

BACKGROUND AND PURPOSE: Beyond the Framingham Stroke Risk Score, prediction of future stroke may improve with a genetic risk score (GRS) based on single-nucleotide polymorphisms associated with stroke and its risk factors. METHODS: The study includes 4 population-based cohorts with 2047 first incident strokes from 22,720 initially stroke-free European origin participants aged ≥55 years, who were followed for up to 20 years. GRSs were constructed with 324 single-nucleotide polymorphisms implicated in stroke and 9 risk factors. The association of the GRS to first incident stroke was tested using Cox regression; the GRS predictive properties were assessed with area under the curve statistics comparing the GRS with age and sex, Framingham Stroke Risk Score models, and reclassification statistics. These analyses were performed per cohort and in a meta-analysis of pooled data. Replication was sought in a case-control study of ischemic stroke. RESULTS: In the meta-analysis, adding the GRS to the Framingham Stroke Risk Score, age and sex model resulted in a significant improvement in discrimination (all stroke: Δjoint area under the curve=0.016, P=2.3×10(-6); ischemic stroke: Δjoint area under the curve=0.021, P=3.7×10(-7)), although the overall area under the curve remained low. In all the studies, there was a highly significantly improved net reclassification index (P<10(-4)). CONCLUSIONS: The single-nucleotide polymorphisms associated with stroke and its risk factors result only in a small improvement in prediction of future stroke compared with the classical epidemiological risk factors for stroke.