Abstract Stroke is a potentially lethal cerebrovascular event. Many research studies devoted to the treatment of stroke. In a recent study, sphingosine-1-phosphate (S1P) has the function of reducing the brain infarct volume. However, no study has yet demonstrated that lysophosphatidic acid (LPA) has this function. LPA and S1P are thought to be the two functionally important LPLs with high structural similarity. Although the neuroprotective function of S1P in TIA rat was confirmed, the effects of LPA on the brain damage after ischemic stroke of animal remain unclear. In this study we evaluated the neuroprotective effects of LPA1/3 receptor agonist (VPC31143; VPC) on rat brains subjecting to permanent middle cerebral artery occlusion (PMCAO). A reliable surgical model of rat PMCAO was first established. Thereafter, the animals were divided into control, vehicle, high-dose VPC, and low-dose VPC groups. The vehicle group received intraperitoneal (i.p.) injection of 3% bovine serum albumin (BSA; 1 ml/kg) 30 minutes after PMCAO surgery. The high-dose VPC and the low-dose VPC group respectively received 0.8 mg/kg and 0.25 mg/kg of i.p. injection of VPC (in 3% BSA) 30 minutes after PMCAO surgery. The mortality rate, infarct volume ratio, and the neurobehavioral outcome were measured 24 hours after PMCAO and statistically analyzed for the difference between treatments. Analyses of the experimental results showed that VPC treatment significantly reduced the mortality rate and the infarct volume ratio of the rats 24 hours after PMCAO. The neurobehavioral scores also showed the improved outcome in stroke rats treated with VPC. The beneficial effect of VPC to the ischemic brain was thought to be mediated through the PI3K signal transduction pathway. Further studies at the transcriptional and the translational levels will further confirm this postulation.

The purpose of this study was to gain understanding of the early symptom experience of ischemic stroke in women. This is the only study of which the researcher is aware in which narrative inquiry was used to examine the period of time from symptom onset until emergency department arrival in women. Data collection was achieved by in-depth interviews during which participants’ stories of stroke were elicited. Individual narrative accounts were created and analyzed using within and across case techniques. The participants were nine women ranging in age from 24-86 years (average age 53). Four participants were Caucasian, three were Hispanic, one was African American and one woman was of mixed race. The participants experienced the onset of stroke as the inability to carry out accustomed activities in usual ways. There was a tendency to objectify the body. Only two participants considered stroke as a possible cause for their symptoms, and the other women attributed symptoms everyday bodily experiences and/or other health conditions. Most participants did not perceive themselves at risk for stroke although all but one woman had risk factors. The participants displayed a variety of responses to symptoms, including trying to continue with usual activities and seeking help as well as deciding not to tell anyone about their symptoms. Symptom response was related to women’s evaluation of and emotional response to symptoms. The actions taken by the participants in response to symptoms were informed by the meaning of the symptoms, and meaning was formed within the context of each woman’s life situation. Few women made the decision to seek medical care on their own, and in every case family members or co-workers were reported to take an active role in getting the participant to the hospital. Some family members were reported to consult with one another before making the decision to call EMS or transporting the participant to the emergency department. Consistent with what was expected from extant research the majority of the participants did not arrive at the hospital in time to be offered treatment with t-PA. Recommendations for future research, stroke education and practice were discussed. / text

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Background: Various randomized-controlled clinical trials (RCTs) have investigated the neuroprotective role of minocycline in acute ischemic stroke (AIS) or acute intracerebral hemorrhage (ICH) patients. We sought to consolidate and investigate the efficacy and safety of minocycline in patients with acute stroke. Methods: Literature search spanned through November 30, 2017 across major databases to identify all RCTs that reported following efficacy outcomes among acute stroke patients treated with minocycline vs. placebo: National Institute of Health Stroke Scale (NIHSS), Barthel Index (BI), and modified Rankin Scale (mRS) scores. Additional safety, neuroimaging and biochemical endpoints were extracted. We pooled mean differences (MD) and risk ratios (RR) from RCTs using random-effects models. Results: We identified 7 RCTs comprising a total of 426 patients. Of these, additional unpublished data was obtained on contacting corresponding authors of 5 RCTs. In pooled analysis, minocycline demonstrated a favorable trend towards 3-month functional independence (mRS-scores of 0–2) (RR = 1.31; 95% CI 0.98–1.74, p = 0.06) and 3-month BI (MD = 6.92; 95% CI − 0.92, 14.75; p = 0.08). In AIS subgroup, minocycline was associated with higher rates of 3-month mRS-scores of 0–2 (RR = 1.59; 95% CI 1.19–2.12, p = 0.002; I2 = 58%) and 3-month BI (MD = 12.37; 95% CI 5.60, 19.14, p = 0.0003; I2 = 47%), whereas reduced the 3-month NIHSS (MD − 2.84; 95% CI − 5.55, − 0.13; p = 0.04; I2 = 86%). Minocycline administration was not associated with an increased risk of mortality, recurrent stroke, myocardial infarction and hemorrhagic conversion. Conclusions: Although data is limited, minocycline demonstrated efficacy and seems a promising neuroprotective agent in acute stroke patients, especially in AIS subgroup. Further RCTs are needed to evaluate the efficacy and safety of minocycline among ICH patients. / Revisión por pares / Revisión por pares

CADASIL est une forme héréditaire, autosomique dominante, de maladie des petits vaisseaux cérébraux dans laquelle surviennent précocement des lésions de la substance blanche cérébrale qui progressent avec le temps, mais dont la nature histopathologique demeure très mal connue. La maladie est causée par des mutations très stéréotypées du récepteur Notch3. Une des signatures de CADASIL est la présence, dans les vaisseaux, d’une accumulation du domaine extracellulaire de NOTCH3 (Notch3ECD). Un faisceau d’arguments suggère que le processus pathogène de CADASIL résulte d’un effet toxique de ces dépôts de Notch3ECD, qui passerait par l’accumulation avec le NOTCH3ECD d’autres protéines de la matrice extracellulaire. Il a cependant été montré que des mutations CADASIL affectent les capacités de signalisation du récepteur, de manière constitutive ou avec le temps, ce qui a conduit à formuler l’hypothèse qu’une perte de fonction Notch3 pourrait également constituer un déterminant important du processus pathogène.Nous avons réalisé une analyse détaillée des lésions de la substance blanche dans un modèle murin de la maladie CADASIL obtenu par surexpression d’un allèle Notch3 avec la mutation R169C / R170C, qui en récapitule les stades précliniques (TgPACNotch3R169C). Ceci a permis de mettre en évidence aux stades précoces un oedème intramyélinique associé à une dégradation / décompaction de la myéline détectable en immunohistochimie dès l’âge de 6 mois. L’analyse de l’intégrité axonale au sein des lésions de la myéline suggère une perte secondaire. Une méthode de quantification semi-automatisée des débris myélinique a été élaborée.Nous avons ensuite testé l’hypothèse qu’une perte de fonction Notch3 pourrait constituer un déterminant majeur dans le processus pathogène de CADASIL. Nous avons pour cela identifié un set de gènes dont l’expression est sensible à la quantité de Notch3, capable de détecter une diminution de moitié de la dose de Notch3. La mesure de l’expression de ces gènes chez des souris Knock-in pour la mutation R170C, hétérozygotes ou homozygotes, a montré que l’activité Notch3 n’était pas diminuée dans ce modèle. Nous avons ensuite étudié l’impact de la suppression des copies endogènes de Notch3 sur les lésions de la substance blanche chez les souris TgPACNotch3R169C, qui n’apparaissent pas aggravées. Ces résultats plaident contre un effet hypomorphe commun à toutes les mutations CADASIL et suggèrent que les lésions de la substance blanche ne sont pas secondaires à un tel effet.Nous avons enfin étudié le rôle pathogène de l’excès de TIMP3 et vitronectine, deux protéines dont il a été démontré qu’elles s’accumulent précocement avec le NOTCH3ECD. En utilisant des approches d’interaction génétique (diminution et/ou augmentation de la quantité de TIMP3 et vitronectine chez les souris TgPACNotch3R169C), nous avons observé un effet différent de l’excès des deux protéines sur les anomalies de la réactivité cérébrovasculaire et celles de la substance blanche. En effet, la réduction de la quantité de vitronectine limite les lésions de la substance blanche sans effet sur la réactivité cérébrovasculaire alors que la réduction de TIMP3 corrige les anomalies vasculaires fonctionnelles sans effet sur la substance blanche. Ces résultats apportent la preuve de concept du rôle pathogène de l’accumulation des protéines TIMP3 et vitronectine dans le processus pathogène de CADASIL et remettent en question les dogmes faisant de l’hypoperfusion le facteur promoteur des lésions de la substance blanche dans la maladie. / CADASIL is an autosomal dominant, hereditary, small vessel disease of the brain causing early and progressive white matter lesions. The histopathological characteristics of these lesions remain poorly known. The disease is caused by stereotyped mutations in the gene coding for the NOTCH3 receptor. One of CADASIL hallmarks is the presence in vessels of an abnormal accumulation of NOTCH3 extracellular domain (NOTCH3ECD). Data suggest that CADASIL pathophysiological process may be caused by a toxic effect resulting from NOTCH3ECD deposits, due to an abnormal recruitment of other extracellular matrix components. However, it has been shown that CADASIL mutations differentially affect Notch3 signaling, constitutively or progressively. The latter observations led scientists to propose the hypothesis that Notch3 loss of function may play an important role in CADASIL pathogenesis.We conducted a detailed white matter analysis in a CADASIL mouse model that overexpresses a Notch3 allele with the R169C/R170C mutation and that recapitulates the preclinical stages of the disease (TgPACNotch3R169C). In this model, we observed intramyelinic edema associated with myelin degradation / decompaction detectable by immunochemistry in the brain of mice as young as 6 months of age. Axonal integrity analysis in myelin lesions suggested that axonal loss may appear secondarily. A semi-quantitative method for the quantification of myelin debris has been developed.Next, we tested the hypothesis that Notch3 loss of function might play a key role in CADASIL pathophysiology. We first identified a set of genes that are sensitive to a reduction in Notch3 dosage by half. Quantification of these genes expression in both heterozygous and homozygous mice Knock-in for the R170C mutation showed that Notch3 activity was not lowered in this model. In addition, we analyzed the effect of a suppression of endogenous Notch3 copies on white matter lesions observed in TgPACNotch3R169C mice and observed no worsening of these lesions. Together these results suggest that hypomorphism is not a feature common to all CADASIL mutations, and that white matter lesions in CADASIL do no result from Notch3 loss of function.Finally, we studied the pathogenic effect of Timp3 and vitronectine accumulation, both proteins having been shown to accumulate with NOTCH3ECD early in the course of the disease. By the use of genetic interaction approaches (lowering and increase in Timp3 and vitronectine in TgPACNotch3R169C mice), we observed differential effects of the proteins on white matter lesions and cerebrovascular reactivity impairment. Indeed, vitronectine lowering improves white matter lesions without any effect on cerebrovascular reactivity while Timp3 diminution restores cerebrovascular reactivity without any effect on white matter lesions. These results provide proof of concept for the implication of TIMP3 and vitronectin excess in CADASIL pathogenesis and questions the dogma that make hypoperfusion the main determinant of white matter lesions in CADASIL.

No description available.

No description available.

Strokes are a leading cause of death and disability in the United States, predominantly caused by ischemic events. Ischemic strokes occur when a clot or other obstruction lodges in a blood vessel of the brain, restricting the movement of blood. Subsequent rapid cell death occurs and often leads to long term neurological deficits. Pial collaterals are a well-established determinant of patient outcome due to their unique ability to remodel into conductance arteries that can reroute blood back to the ischemic tissue. During development, pial collaterals arise within the pia mater and establish connections between distant arterioles of cerebral arteries. Under healthy conditions, these vessels are exposed to bidirectional blood flow, keeping them small and dormant. Following vascular obstruction, pial collaterals are exposed to unidirectional blood flow, triggering them to expand through an adaptive process termed, arteriogenesis, allowing for retrograde perfusion into the obstructed artery and its affected tissue. However, hyperacute arteriogenesis following ischemic stroke has been poorly investigated. The following dissertation aims to address this research gap and leverage the findings to develop therapeutics that enhance arteriogenesis. Previous research has revealed EphA4 restricts arteriogenesis through the Tie2 signaling axis, therefore this work sought to evaluate the endothelial cell (EC) specific role of the EphA4/Tie2 axis in acute arteriogenesis. EC-specific EphA4 KO mice displayed increased pial collateral size from 4.5 to 24-hours post-injury, which was associated with reduced tissue damage, improved cerebral blood flow, and enhanced motor function. Additionally, pharmaceutical stimulation of the Tie2 axis using Vasculotide, an angiopoietin-1 memetic peptide, replicates these findings. Administration of 3ug/kg Vasculotide to wildtype mice immediately after permanent middle cerebral artery occlusion leads to significantly larger pial collateral diameters, correlating with reduced tissue damage and improved functional recovery. Unlike Vasculotide, device stimulation using low intensity focused ultrasound failed to increase collateral diameter, despite resulting in profound neuroprotection. Taken together, this dissertation work demonstrates that the EphA4/Tie2 signaling pathway can be pharmacologically targeted to improve arteriogenesis following ischemic stroke. / Ph.D. / Worldwide, strokes are a leading cause of death and long-term disability with many cases being ischemic strokes, where a blood clot blocks blood flow to the brain. Without the critical oxygen and nutrients that the blood provides, cells in the affected region of the brain begin to rapidly die, leading to neurological deficits. While current treatments focus on removing the clot, it does not guarantee the restoration of blood flow to the damaged area. In contrast, our research focuses on pre-existing blood vessels in the brain, called pial collaterals, that can ease the loss of blood flow after stroke. These vessels, although relatively inactive under normal conditions, can enlarge after a stroke to reroute blood flow to the injured tissue. Thus, pial collateral growth is a critical process in the initial hours after stroke when this blood flow can prevent brain cells from dying. Previous work has shown EphA4, a receptor known for its role in nervous system development, restricts pial collateral size by inhibiting the Tie2 signaling pathway. Loss of EphA4 in endothelial cells allows for Tie2 receptor activation, increased pial collateral size, and decreased tissue damage. To explore therapeutic enhancement of pial collaterals, we administered Vasculotide, a drug that activates the Tie2 receptor, to wildtype mice expressing EphA4 after a stroke. The mice treated with Vasculotide displayed significantly larger pial collateral vessels one day after the stroke, compared to control mice. Moreover, Vasculotide-treated mice exhibited reduced tissue damage and performed better on behavioral assessments. In addition to pharmaceutical stimulation with Vasculotide, we also investigated the effects of low-intensity focused ultrasound (LIFU) on collateral size. LIFU treatment resulted in decreased tissue damage compared to untreated controls; however, it did not impact collateral size. These findings suggest that inhibiting EphA4 or stimulating Tie2 could serve as novel therapeutic targets to promote the expansion of pial collateral blood vessels, thereby restoring critical blood flow to injured areas of the brain.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In ischemic stroke, damage to the brain is caused by a reduction or complete blockage of blood flow to parts of the brain, resulting in glucose and oxygen deficiency. It is a leading cause of mortality and disability particularly in the elderly. The majority of strokes are not fatal and survivors are at a high risk of subsequent vascular complications and new vascular accidents. Hypertension is the most important risk factor in strokes, being that it is present in 70% of all cases. Oxidative stress is believed to be one of the mechanisms taking part in neuronal damage in stroke. The key role the cholinergic system plays in normal brain functions and in memory disturbances of several pathological processes, such as in cerebral blood flow regulation, has been well documented. This study investigated the oxidative status and acetylcholinesterase (AChE) activity in whole blood in patients diagnosed with the acute and chronic stage of ischemia, as well as with hypertension. We determined the catalase activity in the blood, reduced glutathione (GSH) in erythrocytes, and TBARS and protein carbonyl content from serum samples. The oxidative profile of lipids and proteins represented by MDA levels and protein carbonylation content, respectively, showed increased levels both in the acute ischemic group and in the hypertensive group, when compared to the control. Catalase activity and GSH levels in the acute group also were higher than in the hypertensive and control groups. No difference was found between the catalase activity of the chronic ischemic group and the hypertensive group (p< 0.05). The activity of AChE in acute ischemic patients was significantly higher than that presented by the control, hypertensive and chronic ischemic patients (p<0.05). No significant difference was observed between the chronic and control groups. The hypertensive group presented AChE activity significantly lower than the other groups. The results suggest increased antioxidant defense as a compensatory mechanism in consequence of the overproduction of reactive oxygen species (ROS) after acute stroke. This sudy also demonstrated that hypertension, in and of itself, acts as a prevalent risk factor of stroke, contributing to oxidative cellular damage. Futhermore, the results revealed that ischemia exerted a modulator effect on AChE activity in erythrocytes, in an attempt to maintain adequate levels of the neurotransmitter acetylcholine (ACh), as a response to the differents phases following neurological injury caused by ischemia. The ischemic event, in spite of having a defined location, results in a systemic disorder that induces changes, which can be detect by mesuring the peripheral markers of oxidative stress and AChE activity in erytrocytes. / No acidente vascular isquêmico, o dano ao encéfalo é causado por uma redução ou um bloqueio completo do fluxo sangüíneo resultando em liberação deficiente de glicose e oxigênio. É uma das principais causas de mortalidade e incapacitação entre os idosos. Em sua maioria não são fatais e os sobreviventes têm alto risco de complicações vasculares subseqüentes. A hipertensão é o mais importante fator de risco para o acidente vascular cerebral, presente em 70% de todos os casos. Acredita-se que o estresse oxidativo é um dos mecanismos associados ao dano neuronal após o evento isquêmico. O papel chave que o sistema colinérgico desempenha nas funções normais do encéfalo e distúrbios de memória de vários processos patológicos assim como no controle do fluxo sanguíneo cerebral vem sendo bem documentado. Este trabalho investigou o perfil oxidativo e a atividade da enzima acetilcolinesterase sangüínea em pacientes com diagnóstico de acidente vascular cerebral isquêmico, na fase aguda e crônica assim como a influência da hipertensão em tal patologia. Determinou-se a atividade da catalase em sangue total, os níveis de glutationa reduzida em eritrócitos, TBARS e o conteúdo de proteína carbonil em amostras de soro da população estudada. O perfil oxidativo de lipídeos e proteínas, representado pelos níveis de MDA e conteúdo de proteína carbonil mostrou-se aumentado na fase aguda do evento isquêmico e no grupo hipertenso quando comparado com o controle. A atividade da catalase e os níveis de glutationa reduzida nos pacientes pertencentes ao estágio agudo encontraram-se aumentadas em relação aos grupos hipertenso e controle. Nenhuma diferença na atividade da catalase foi encontrada entre pacientes do estágio crônico da isquemia carebral e aqueles do grupo hipertenso (p<0,05). A atividade da AChE sangüínea durante a fase aguda do acidente vascular isquêmico foi aumentada em relação àquela apresentada pelos grupos controle, hipertenso e crônico (p< 0,05). Também, nenhuma diferença foi observada entre o grupo crônico e o controle. O grupo hipertenso apresentou atividade da AChE significativamente menor que os outros grupos. Os resultados sugerem que o aumento da defesa antioxidante age como um mecanismo compensatório como consequência da superprodução de espécies reativas de oxigênio (EROs) após o evento isquêmico agudo. Este estudo também demonstrou que a hipertensão atua como um fator de risco prevalente para o acidente vascular isquêmico, contribuindo para o dano oxidativo celular. Os resultados também revelaram que a isquemia exerce efeito modulador na atividade da AChE em eritrócitos, a fim de manter adequados níveis do neurotransmissor acetilcolina (ACh) em resposta as diferentes fases da injúria neurológica causada pela isquemia. Conclui-se então que o evento isquêmico, apesar de ter localização definida, resulta em uma desordem sistêmica, induzindo mudanças, as quais podem ser detectadas pela medida de marcadores periféricos do estresse oxidativo e atividade da AChE sangüínea.

Epidemiological studies report that infarct size is decreased and stroke outcomes are improved in young females when compared to males. However, mechanistic insight is lacking. We posit that sex-specific differences in glial cell functions occurring immediately after ischemic stroke are a source of dichotomous outcomes. In this study we assessed astrocyte Ca2+ dynamics, aquaporin 4 (AQP4) polarity, Sloop expression pattern, as well as, microglia morphology and phagocytic marker CD11b in male and female mice following 60 min of middle cerebral artery (MCA) occlusion. We reveal sex differences in the frequency of intracellular astrocyte Ca2+ elevations (F-(1,F-86) = 8.19, P = 0.005) and microglia volume (F-(1,F-40) = 12.47, P = 0.009) immediately following MCA occlusion in acute brain slices. Measured in fixed tissue, AQP4 polarity was disrupted (F-(5,F-86) = 3.30, P = 0.009) and the area of non-S100 beta immunoreactivity increased in ipsilateral brain regions after 60 min of MCA occlusion (F-(5,F-86) = 4.72, P = 0.007). However, astrocyte changes were robust in male mice when compared to females. Additional sex differences were discovered regarding microglia phagocytic receptor CD11b. In sham mice, constitutively high CD11b immunofluorescence was observed in females when compared to males (P = 0.03). When compared to sham, only male mice exhibited an increase in CD11b immunoreactivity after MCA occlusion (P = 0.006). We posit that a sex difference in the presence of constitutive CD11b has a role in determining male and female microglia phagocytic responses to ischemia. Taken together, these findings are critical to understanding potential sex differences in glial physiology as well as stroke pathobiology which are foundational for the development of future sex-specific stroke therapies. (C) 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Remote ischemic conditioning (RIC) is a noninvasive procedure where blood flow to a limb is repetitively reduced, sometimes called an “exercise memetic”. RIC delivered before (pre-RIC) or after (post-RIC) stroke is reportedly neuroprotective in preclinical stroke models. A review of the preclinical RIC literature revealed that studies almost exclusively use male subjects and a single stroke model (MCAO) that produces a large injury (~34% of hemisphere). To improve clinical translation, efficacy should be demonstrated in multiple stroke models and both sexes. Furthermore, the restorative potential of RIC (delivered past the neuroprotection window) to improve stroke recovery remains to be investigated. In male and female Sprague-Dawley rats (n=129) a standardized session (5min inflation, 5min deflation, 4 repetitions) of RIC was delivered using a pressurized cuff on the hindlimb. RIC was either delivered once 18h before, once 4hr acutely after or daily for 28 days beginning day 5 after endothelin-1 (ET-1) stroke. Infarct volumes were assessed 24hrs after stroke using MRI. To determine if RIC efficacy varied across stroke size, a hierarchical cluster analysis was used to divide rats into subgroups based on stroke size (small/large). RIC was effective in ET-1 which produced smaller strokes (“small”:5.2%, “large”:18.0% of hemisphere) than MCAO (~34%). This is more comparable to injury sizes seen clinically (4.5-14.0%). “Small” (42±4mm3) strokes were reduced by 39% (p=0.010, d=0.29) and “large” (146±8mm3) strokes were reduced by and 35% (p<.00001, d=1.41). Pre-RIC reduced infarct volume by 41% (p=<0.0001, d=0.92) versus 29% (p=0.009, d=0.43) in post-RIC. Interestingly, RIC is more effective in males, with double the infarct volume reduction of 46% (p<0.0001, d=0.94) compared with 23% (p=0.013, d=0.42) in females. Although RIC did not show restorative potential to improve motor stroke recovery, RIC is neuroprotective now with stronger clinically relevant evidence. RIC is effective across stroke models, stroke sizes and sex. Application of RIpreC to prevent stroke following a transient ischemic attack or recurrent stroke (especially in males with “large" strokes) would have the greatest potential.