The role of chemokines in immune function is clearly established. Recent evidence suggests that these molecules also play an important role in the CNS as modulators of neuronal activity. The chemokine CXCL12 has been identified in several regions of the adult rat brain including the substantia nigra, ventral tegmental area and caudate putamen. CXCR4, a receptor activated by CXCL12, is expressed by dopaminergic neurons in the substantia nigra. The research presented herein explored the behavioral modulation of CXCL12, expression of the CXCR4 receptor in the forebrain of the adult rat and the effect of CXCL12 administration on extracellular dopamine and glutamate release in the medial shell of the nucleus accumbens. This research furthered our understanding of how CXCL12 can affect behavior and suggested that the modulation of cocaine-induced behavior by CXCL12 is due to an interaction with CXCR4 receptors in the mesolimbic and nigrostriatal dopamine pathways. The data presented tested the effects of intracranial injections of CXCL12 on cocaineinduced locomotion and stereotypic activity in adult male Sprague Dawley rats. Results demonstrate that intracerebroventricular administration of CXCL12 (25 ng/4 μl) 15 minutes prior to cocaine (20 mg/kg IP) produced a significant potentiation of both ambulatory and stereotypic activity as compared to cocaine alone. The effects of CXCL12 were blocked by administration of the selective CXCR4 antagonist, AMD 3100. Administration of CXCL12 into specific brain regions was performed to further understand the site of action of CXCL12. Bilateral administration of CXCL12 (25 ng/0.5 μl) into the ventral tegmental area 15 minutes prior to cocaine (20 mg/kg IP) significantly potentiated cocaine-induced ambulatory activity, whereas microinjections of CXCL12 into the caudate putamen selectively increased stereotypy. Conversely, administration of CXCL12 into the lateral shell of the nucleus accumbens resulted in an inhibition of cocaine-stimulated ambulatory activity. No alterations in ambulatory or stereotypic activity were observed following CXCL12 administration into the core of the nucleus accumbens. Immunohistochemistry results showed evidence of CXCR4 within the caudate putamen and lateral shell of the nucleus accumbens. Dual labeling immunofluorescence demonstrated that CXCR4 is co-expressed on cholinergic and GABAergic neurons, including co-localization with the D1 dopamine receptor in both the caudate putamen and lateral shell of the nucleus accumbens. Results demonstrated that CXCR4 is co-expressed with choline acetyl transferase, a marker for cholinergic neurons, with GAD C38, a marker for GABAergic neurons, and with the D1 dopamine receptor, also a marker for GABAergic medium spiny neurons. High pressure liquid chromatography studies were conducted using brain dialysate collected from microdialysis probes surgically implanted in the medial shell of the nucleus accumbens. Results demonstrated no significant change in extracellular dopamine or glutamate following an acute administration of CXCL12. The research presented herein sought to determine the behavioral modifications of CXCL12 as well as the localization of CXCR4 in the forebrain of the adult rat. This research also examined changes in extracellular dopamine and glutamate levels following CXCL12 administration. Results demonstrated that CXCL12 does alter the behavioral activity of cocaine. Results also showed that CXCR4 is localized on cholinergic and GABAergic neurons that could be contributing to the behavioral modification. These results have extended our understanding of the complex mechanisms of CXCL12 and CXCR4 in the mesolimbic and nigrostriatal dopamine pathways of the adult rat brain. / Pharmacology

No description available.

Balali_Pargol_MSc thesis_Neuroscience department_2023Sep / Background: Cerebral microbleeds are asymptomatic neuroimaging markers of small vessel disease (SVD), visualized as small hypointensities on blood-sensitive magnetic resonance imaging (MRI) sequences. Patients with ischemic stroke and microbleeds are at a higher risk of future ischemic stroke and intracranial hemorrhage. Antithrombotic therapies, the mainstay treatment of secondary stroke prevention, are associated with an increased risk of bleeding. This raises concerns surrounding the net benefit of antithrombotic therapies in these hemorrhage-prone patients. The overarching aim of this thesis is to determine the safety of antithrombotic treatments in patients with hemorrhage-prone SVD marked by microbleeds on MRI or prior intracerebral hemorrhage (ICH). I aimed to characterize the association between baseline microbleeds and the risk of future clinical outcomes in patients with ischemic stroke and whether there exists treatment effect modification of different anticoagulants on clinical outcomes according to microbleeds presence, location, and number. Methods: We performed post hoc analyses on two multicenter previously conducted randomized trials in patients with non-cardioembolic ischemic stroke. For the PACIFIC-STROKE trial, we used multivariable regression models to determine the contribution of microbleeds to the risk of new microbleeds, hemorrhagic transformation (HT), ischemic stroke, intracranial hemorrhage, and death. We assessed the treatment effect of asundexian, a factor XIa inhibitor, vs. placebo on these clinical outcomes, stratified by microbleeds presence, location, and number. I was trained on standardized rating of microbleeds on MRI, achieved excellent interrater reliability, and rated all DATAS-II participant MRIs. I used multivariable logistic regression models to identify the association between microbleeds and HT and 90-day excellent functional outcome. I assessed the interaction between treatment with dabigatran, a direct thrombin inhibitor, vs. aspirin and microbleeds for these outcomes. Separately, I performed a review of the literature and wrote an editorial discussing the optimum timing of antiplatelet re-initiation after ICH. Results: The PACIFIC-STROKE post hoc analyses showed that microbleeds are associated with a 1.6-fold and 4.4-fold higher risk of HT and new microbleeds, respectively. The DATAS-II exploratory analyses demonstrated no association between the risk of outcomes and microbleeds presence. We found no interaction between treatment assignment and microbleed presence for any of the clinical outcomes investigated in either of these studies. Based on the totality of evidence, we concluded that early resumption of antiplatelets in ICH survivors is likely to be safe. Conclusion: Our findings do not support existing concerns surrounding the use of anticoagulants in patients with acute ischemic stroke and microbleeds on MRI, nor for the early resumption of antiplatelets in ICH survivors. / Thesis / Master of Science (MSc) / Diseases of small brain blood vessels can lead to strokes due to blockage or bleeding. Small, asymptomatic brain bleeds on MRIs (microbleeds) are common among affected patients. Patients with clot-induced stroke and microbleeds have a higher risk of both types of strokes. Blood thinners are standard treatments to prevent future clotting events after clot-induced stroke. However, their potential to increase the risk of brain bleeding has raised concerns regarding their use in patients with microbleeds or bleeding-induced stroke. We assessed information from two large, previously completed randomized trials to evaluate the safety of strong blood thinners (anticoagulants) in patients with clot-induced stroke and microbleeds. Additionally, we evaluated the risk vs. benefit of restarting milder blood thinners (antiplatelets) early after bleeding-induced stroke. Bleeding was more prevalent in patients with microbleeds; however, the effect of the anticoagulants tested on bleeding outcomes was not modified by microbleed presence. Overall, our findings suggest that blood thinners are safe in patients with clot-induced stroke and microbleeds, and that early resumption of antiplatelets seems safe in patients with bleeding-induced stroke.

Part A of two Project Reports; Part B can be found at http://hdl.handle.net/11375/17660 / <p> The recent development of a technique for the synthesis of the molecule 5-(¹⁸F) fluoro-dopa has opened a vast field of research into the study of the intracerebral metabolism. In order to take full advantage of this new tracer compound it will be necessary to use an imaging system which will be capable of providing three dimensional information concerning the rapid changes in activity as the ¹⁸F travels through the brain. This report describes the results os investigations into a possible design for a device which would be capable of this type of dynamic imaging. The design in question employs multiwire proportional chambers (MWPC) as detectors of the .511 MeV gamma rays which result from the annihilation of the positron emitted in the decay of ¹⁸F. </p> <p> For comparison purposes, a breif review of various other types of positron tomographic systems which are presently in use or under development is presented. This review emphasises the resolution, data aquisition speed, and instalation cost for each of these designs. </p> <p> In order to eliminate the need for costly research into the various design aspects of multiwire proportional chambers for use with positron annihilation radiation, the design presented here relies exclusively on methods and designs developed and proven feasible by other groups. These are incorporated into a system to suit the present needs. </p> <p> The design presented uses two pairs of 50x50 cm² MWPC's at 180° to each other and separated by approximately 50 cm. The chambers utilize electromagnetic delay-line readout techniques for the anode and wound bi-filar cathode planes. They are filled with a "magic gas" mixture at a slightly positive pressure. The effeciency of the chambers for .511 MeV photons is increased by employing "sandwich" type converters. Signals from the detectors are transfered to a small computer where they are stored for later tomographic reconstruction off-line. </p> <p> On the basis of the working designs from which the present design has been drawn, one would expect the positron camera to have a sensitivity of better than 1000 counts/second-microcurie. The total costs of development and construction leading up to a working device suitable for clinical use, not including the cost of a dedicated computer, are estimated to be less than seventy five thousand dollars. </p> / Thesis / Master of Engineering (ME)

No description available.

Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor in adults for which overall prognosis remains poor despite recent treatment advances, thus emphasizing the need for developing effective therapeutic agents. Styryl sulfones belong to a class of non-ATP competitive antineoplastic agents in early stage clinical trials. Detailed investigation of the pharmacokinetics (PKs) and pharmacodynamics (PDs) of novel agents in the preclinical stage plays a pivotal role in drug development that could be applied to guide clinical trials. The main goal of the project was to undertake comprehensive PK and PD evaluation of new agents for brain tumor therapy and in the process establish a PK/PD strategy for the development of such novel agents. The current project was aimed to evaluate the potential of a styryl benzyl sulfone compound, ON01910.Na, as a chemotherapeutic agent for the treatment of GBMs using PK/PD approaches. First, the systemic pharmacokinetics of ON01910 was characterized following single dose intravascular administration of ON01910.Na in healthy mice over a 50-fold dose range of 5 mg/kg - 250 mg/kg. Secondly, an evaluation of the brain and brain tumor disposition of ON01910 was conducted in an orthotopic U87 glioma model in mice using a steady-state dosing regimen, and, in addition, using the same brain tumor model its pharmacodynamic and antiangiogenic activity were determined following multiple dosing. ON01910 exhibited nonlinear pharmacokinetics in the dose range of 50 mg/kg - 250 mg/kg. It showed inadequate brain and brain tumor penetration and insignificant antiangiogenic and antiproliferative activity. The limited brain tumor penetration and activity of ON01910 in the intracerebral glioma model led to the evaluation of ON013105, a prodrug of its more lipophilic anticancer congener, ON013100. A similar PK/PD approach as for ON01910.Na was applied wherein systemic pharmacokinetic properties of ON013105 and its active form, ON013100 in healthy mice, as well as an analysis of their brain and brain tumor distribution following steady-state dosing regimen were determined following administration of prodrug. The active form, ON013100 showed appreciable brain and brain tumor penetration while the prodrug did not. Subsequent pharmacodynamic investigations conducted in vitro identified phosphorylated-ERK (pERK) as a PD marker. To assess time-dependent PK/PD characteristics, mice bearing intracerebral U87 glioma were administered ON013105 at 100 mg/kg intravenously and plasma, brain and brain tumor concentrations of ON013105 and its active form, ON013100 were quantitated as well as tumoral pERK levels. Further, a PK-PD model was developed that characterized plasma, brain and brain tumor concentration-time profiles of ON013105 and ON013100 and tumoral pERK levels. In summary, a PK/PD-driven approach was applied to evaluate and select novel compounds that may have potential in the treatment of brain tumors. The progression of studies yielded one compound, ON013100 that possessed favorable brain tumor distribution and showed PD activity that warrant continued evaluation. / Pharmaceutical Sciences

Stroke is a common and multifactorial disease influenced by genetic and environmental risk factors. It is a highly heterogeneous entity consisting of two main types, ischemic (80%) and hemorrhagic (20%) stroke. The most common form of hemorrhagic stroke is intracerebral hemorrhage (ICH). Ischemic stroke mainly results from thrombotic or embolic events, while ICH is caused by the rupture of an artery in the brain. The mean age of first-ever stroke is 75 years (73 vs. 78 years, for men and women, respectively) and the age-specific stroke incidence is higher for men as compared to women, suggesting that hormonal factors confer protection. A large body of experimental and observational studies shows that estrogens exert beneficial effects in the cardiovascular system. However, large, recent, clinical randomized trials have failed to demonstrate a lower risk of stroke with hormone replacement therapy (HRT) in elderly postmenopausal women. It is possible that HRT may only protect a subgroup of women. Here, genetic predisposition might be involved. Stroke incidence is 50% higher in northern compared to southern Sweden, suggesting a genetic predisposition in this population. This relatively homogeneous population displays founder effects, making it well suited for genetic studies. Since 1985, the MONICA and VIP projects have conducted large-scale cardiovascular health surveys in this population. Information about conventional stroke risk determinants and also DNA have been collected, and two prospective, nested case-referent cohorts (113 cases and 226 controls; 275 cases and 549 controls) have been sampled. To investigate whether genes of the estrogen signaling system may be important in stroke development, we performed genetic association studies, including specific functional single nucleotide polymorphisms in the genes for estrogen receptor alpha (ERα, ESR1), and its target genes osteoprotegerin (OPG, TNFRS11B) and interleukin-6 (IL-6, IL6). We found a significant association between the common c.454-397T/T genotype in ESR1 and ICH, remaining after adjustments for conventional stroke risk factors. The c.454-397T/T genotype also associated with increased systolic (SBP) and diastolic blood pressure (DBP). The combination of c.454- 397T/T and either hypertension, increased SBP, or increased DBP boosted this association substantially and significant synergistic effects on ICH risk between this genotype and increased blood pressure were demonstrated. In a second study, we found a similar association between the common OPG-1181C/C genotype and ICH. Cognitive impairments, including spatial memory and learning deficiencies, are common after stroke. Estrogens improve cognitive functions, including memory and learning processes, in postmenopausal women and ovariectomized rodents. Post-ischemic housing of rats in an enriched environment (EE) improves recovery of spatial memory and learning impairments. Both estrogen and EE induce neuroplasticity in the hippocampus. We hypothesized that 17β- estradiol combined with EE would accelerate recovery after experimental focal brain ischemia in ovariectomized rats and that such improvements could be related to expression of nerve growth factor-induced gene A (NGFI-A) in the hippocampus. Five to six weeks after middle cerebral artery occlusion, 17β-estradiol–treated rats housed in an EE showed significant improvements in cognitive function (i.e., shorter latency and path in the Morris water maze task) and significantly higher NGFI-A mRNA expression in bilateral cornu ammonis 1 (CA1) and ipsilateral dentate gyrus (DG) compared to placebo-treated animals in EE. In conclusion, we present evidence for the association between polymorphic variants in the ESR1 and TNFRS11B genes and ICH and show that 17β-estradiol in combination with EE accelerates cognitive functions in a rat stroke model, putatively through upregulation of NGFI-A in hippocampal subregions. These findings may contribute to an increased understanding of the underlying genetic etiology of ICH and may be informative for the primary prevention of this disease. They also provide hope for 17β-estradiol combined with early environmental enrichment as a novel therapeutic option following ischemic stroke.

O Acidente Vascular Encefálico (AVE) Hemorrágico representa mais de 10% de todos os casos de AVE e possui altas taxas de morbidade e de mortalidade. Os pacientes que sobrevivem a este evento permanecem com alguma disfunção motora, que algumas vezes é incapacitante. O extravasamento de sangue em um AVE hemorrágico ocorre, geralmente, em regiões onde há bifurcação de pequenas arteríolas penetrantes, como na região dos núcleos da base. O estriado, importante componente dessa região, está relacionado a funções motoras superiores, como o planejamento e a execução do movimento. Alguns estudos demonstram que o pré-condicionamento (PC) isquêmico pode gerar a tolerância a outros eventos que acometem o sistema nervoso. O PC é definido como fenômeno decorrente da exposição de um tecido ou órgão a um insulto sub-letal capaz de resultar em adaptações determinantes para a tolerância tecidual. Isso ocorre mesmo quando esses dois estímulos são de origens diferentes; neste caso diz-se que o PC desenvolveu tolerância cruzada. Desta forma, o presente estudo dedicou-se ao estudo de efeitos celulares e funcionais do pré-condicionamento isquêmico, por oclusão bilateral das artérias carótidas durante 10 minutos, sobre o modelo de hemorragia intracerebral (HIC), por administração intraestriatal de colagenase do tipo IV-S em ratos. A hipótese de trabalho era de que o PC causaria tolerância cruzada para a HIC, e consequente neuroproteção avaliada por testes motores, volume de lesão, com envolvimento de astrocitose e de micróglia reativa Foram usados 67 ratos machos Wistar adultos, divididos em 4 grupos: Sham (controle cirúrgico), PC, HIC, PC+HIC. Assim, os animais dos grupos PC e PC+HIC foram submetidos ao pré-condicionamento e 24 horas depois os animais HIC e PC+HIC receberam a injeção de colagenase, enquanto os animais Sham e PC receberam uma injeção de salina. A avaliação motora dos animais foi realizada a partir dos testes do cilindro e do Staircase. Trinta e quatro dias após a HIC os animais foram perfundidos e o estriado ipsilateral à injeção foi dissecada para obtenção de amostras teciduais necessárias à avaliação da perda tecidual e quantificação de intensidade de fluorescência de GFAP (proteína glial fibrilar ácida) e OX-42, importantes marcadores de astrócitos e microglia, respectivamente. Os resultados demonstram que: a) a HIC causa deficits motores em ambos os testes realizados, e que o PC reverte este efeito; b) a HIC causa lesão estriatal que não é revertido pelo pré-condicionamento; c) a HIC causa aumento da intensidade de fluorescência para GFAP e para OX-42, e o PC reverte apenas a reatividade da micróglia. Em conjunto, sugere-se que o pré-condicionamento isquêmico causa tolerância cruzada com a hemorragia intracerebral experimental, resultando em proteção funcional, mas não morfológica, possivelmente associada a uma diminuição da reatividade da microglia após o evento hemorrágico. / Hemorrhagic Vascular Stroke (EVA) represents more than 10% of all stroke cases with high rates of morbidity and mortality. Patients who survive this event, remain with some motor dysfunction, which is sometimes disabling. The extravasation of blood in a hemorrhagic stroke occurs, generally, in regions where there is bifurcation of small vessels, as in the region of striatum. The striatum is related to the higher motor functions, such as the planning and execution of the movement. Some studies have shown that preconditioning (PC) can generate a tolerance to other events that accompany the nervous system. The PC is presented as the source of the exposure of a sub-lethal, resulting in an adaptation of determinants to a tissue tolerance. Thus, the present study aimed shows the ischemic preconditioning effects, by bilateral occlusion of the carotid arteries for 10 minutes, on the intracerebral hemorrhage (ICH) model, by intra- striatum administration of type IV S collagenase in rats. The working hypothesis was tolerance to HIC, and consequent neuroprotection by motor function, lesion volume, astrocytosis and reactive microglia. A total of 84 male Wistar adult rats were divided into 4 groups: Sham (surgical control), PC, HIC, PC + HIC Thus, the animals of the PC and PC + HIC groups were introduced to the preconditioning and 24 hours later, the HIC and PC + HIC animals received a collagenase injection, while the Sham and PC animals received a saline injection. The evaluation of the animal function was performed from cylinder and Staircase tests. Thirty-four days after the surgery, the striatum was dissected and prepared to lesion volume analysis and fluorescence intensity of GFAP quantification (acid glial fibrillary protein) and OX-42, important astrocyte and microglia markers respectively. The results demonstrate that: a) an HIC causes motor deficits in both tests performed, and that the PC reverses this effect; b) an ICH causes a striatal lesion that is not reversed by preconditioning; c) an HIC promoted high fluorescence intensity for GFAP and OX-42, and PC reverses the microglia reactivity. Taken together, we suggest that ischemic preconditioning combined with experimental intracerebral hemorrhage, promotes functional but not morphological protection, being associated with the microglial reactivity decrease after the hemorrhagic event.

The neurological wake-up test, NWT, is a clinical monitoring tool that can be used to evaluate the level of consciousness in patients with traumatic brain injury (TBI) and subarachnoid haemorrhage (SAH) during neurocritical care (NCC). Since patients with severe TBI or SAH are often treated with mechanical ventilation and sedation, the NWT requires that the continuous sedation is interrupted. However, interruption of continuous sedation may induce a stress response and the use of the NWT in NCC is controversial. The effects of the NWT on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were evaluated in 21 patients with TBI or SAH. Compared to baseline when the patients were sedated with continuous propofol sedation, the NWT resulted in increased ICP and CPP (p&lt;0.05). Next, the effects of the NWT on the stress hormones adrenocorticotrophic hormone (ACTH), cortisol, epinephrine and norepinephrine were evaluated in 24 patients. Compared to baseline, the NWT caused a mild stress response resulting in increased levels of all evaluated stress hormones (p&lt;0.05). To compare the use of routine NCC monitoring tools, the choice of sedation and analgesia and the frequency of NWT in Scandinavian NCC units, a questionnaire was used. The results showed that all 16 Scandinavian NCC units routinely use ICP and CPP monitoring and propofol and midazolam were primary choices for patient sedation in an equal number of NCC units. In 2009, the NWT was not routinely used in eight NCC units whereas others used the test up to six times daily. Finally, intracerebral microdialysis (MD), brain tissue oxygenation (PbtiO2) and jugular bulb oxygenation (SjvO2) were used in 17 TBI patients to evaluate the effect of the NWT procedure on focal neurochemistry and cerebral oxygenation. The NWT did not negatively alter interstitial markers of energy metabolism or cerebral oxygenation. In conclusion, the NWT induced a mild stress response in patients with TBI or SAH that did not result in a detectable, significant secondary insult to the injured brain. These results suggest that the NWT may safely be used as a clinical monitoring tool in the NCC of severe TBI and SAH in a majority of patients.

Patients with mechanical heart valves who present with intracranial haemorrhage are initially treated by reversing their coagulopathy. However, these patients will ultimately require that their oral anticoagulant be restarted. The time at which oral anticoagulants are restarted is critical since restarting too early may increase the risk of recurrent bleeding, while withholding anticoagulants increases the patient’s risk of thromboembolic events. The ideal time to restart patients on their oral anticoagulant medication is defined as the time at which all these risks are minimized. This thesis includes a systematic review and meta-analysis of the literature. The main outcomes were recurrent haematoma, valve thrombosis, stroke and peripheral emboli. Results were stratified by types of intracranial haemorrhage. We also conducted a survey to gain insight into current practices of neurosurgeons and thrombosis experts in Canada and USA when they are faced with deciding on anticoagulant restart times in patients with ICH. Results were stratified by type of intracranial bleed and participants’ characteristics and demographics. The systematic review identified that the ideal time for restarting anticoagulant therapy in patients following an ICH is unknown. Meta-analysis was limited by the heterogeneity of the studies. The survey results indicated that physicians had a wide range of practice and that their practice was dependent on the patient’s clinical features, but many physicians would restart oral anticoagulants between 4 and 14 days after the haemorrhage. For this reason we have proposed a multi centre cohort study to investigate the safety and efficacy of restarting patients on anticoagulation therapy between day 5 and 9 post haemorrhage. A full study protocol is presented in this thesis.