Exploring the role of in-patient magnetic resonance imaging use among admitted ischemic stroke patients in improving patient outcomes and reducing healthcare resource utilization.

Purpose: Despite the diagnostic and etiological significance of in-patient MRI in ischemic stroke (IS), its utilization is considered resource-intensive, expensive, and thus limiting feasibility and relevance. This study investigated the utilization of in-patient MRI for IS patients and its impact on patient and healthcare resource utilization outcomes. Methods: This retrospective registry-based study analyzed 1,956 IS patients admitted to Halifax's QEII Health Centre between 2015 and 2019. Firstly, temporal trends of MRI and other neuroimaging utilization were evaluated. Secondly, we categorized the cohort into two groups (MRI vs. No MRI; in addition to a non-contrast CT) and investigated adjusted differences in patient outcomes at admission, discharge, and post-discharge using logistic regression. Additionally, we analyzed healthcare resource utilization using Poisson log-linear regression. Furthermore, patient outcomes significantly associated with MRI use underwent subgroup analysis for stroke severity (mild stroke including transient ischemic attack vs. moderate and severe stroke) and any acute stage treatment (thrombolytic or thrombectomy or both vs. no treatment) subgroups, while using an age and sex-adjusted logistic regression model. Results: MRI was used in 40.5% patients; non-contrast CT in 99.3%, CT angiogram in 61.8%, and CT perfusion in 50.3%. Higher MRI utilization was associated with male sex, younger age, mild stroke, wake-up stroke, and no thrombolytic or thrombectomy treatment. MRI use was independently associated with lower in-hospital mortality (adjusted OR, 0.23; 95% CI, 0.15-0.36), lower symptomatic neurological status changes (0.64; 0.43-0.94), higher home discharge (1.32; 1.07-1.63), good functional outcomes at discharge (mRS score 0-2) (1.38; 1.11-1.72), lower 30-day stroke re-admission rates (0.48; 0.26-0.89), shorter hospital stays (regression coefficient, 0.92; 95% CI, 0.90-0.94), and reduced direct costs of hospitalization (0.90; 0.89-0.91). Subgroup analysis revealed significantly positive association of MRI use with most patient outcomes in moderate and severe strokes subgroup and non-acutely treated subgroup. Conversely, outcomes in mild strokes (including TIAs) subgroup and acute treatment subgroup were comparable regardless of MRI use. Conclusion: A substantial proportion of admitted IS patients underwent MRI, and MRI use was associated with improved patient outcomes and reduced healthcare resource utilization. Considering the multifactorial nature of IS patient outcomes, further randomized controlled trials are suggested to investigate the role of increased MRI utilization in optimizing in-patient IS management.

Impact of early MRI in ischemic strokes beyond hyper-acute stage to improve patient outcomes, enable early discharge, and realize cost savings.

BACKGROUND: Early in-patient MR Imaging may assist in identifying stroke etiology, facilitating prompt secondary prevention for ischemic strokes (IS), and potentially enhancing patient outcomes. This study explores the impact of early in patient MRI on IS patient outcomes and healthcare resource use beyond the hyper-acute stage. METHODS: In this retrospective registry-based study, 771 admitted transient ischemic attack (TIA) and IS patients at Halifax's QEII Health Centre from 2015 to 2019 underwent in-patient MRI. Cohort was categorized into two groups based on MRI timing: early (within 48 h) and late. Logistic regression and Poisson log-linear models, adjusted for age, sex, stroke severity, acute stroke protocol (ASP) activation, thrombolytic, and thrombectomy, were employed to examine in-hospital, discharge, post-discharge, and healthcare resource utilization outcomes. RESULTS: Among the cohort, 39.6 % received early in-patient MRI. ASP activation and TIA were associated with a higher likelihood of receiving early MRI. Early MRI was independently associated with a lower rate of symptomatic changes in neurological status during hospitalization (adjusted odds ratio [OR], 0.42; 95 % confidence interval [CI], 0.20-0.88), higher odds of good functional outcomes at discharge (1.55; 1.11-2.16), lower rate of non-home discharge (0.65; 0.46-0.91), shorter length of stay (regression coefficient, 0.93; 95 % CI, 0.89-0.97), and reduced direct cost of hospitalization (0.77; 0.75-0.79). CONCLUSION: Early in-patient MRI utilization in IS patients post-hyper-acute stage was independently associated with improved patient outcomes and decreased healthcare resource utilization, underscoring the potential benefits of early MRI during in-patient management of IS. Further research, including randomized controlled trials, is warranted to validate these findings.

Is improved access to magnetic resonance imaging imperative for optimal ischemic stroke care?

Neuroimaging, including CT and MRI, is integral to ischemic stroke (IS) treatment, management, and prevention. However, the use of MRI for IS patients is limited despite its potential to provide high-quality images that yield definitive information related to the management of IS. MRI is beneficial when the information provided by CT is insufficient for decisions related to the diagnosis, etiology, or treatment of IS. In the emergency setting, MRI can improve the diagnostic accuracy of CT-negative acute ischemic strokes (AIS) and ensure a better selection of patients for reperfusion therapies with thrombolysis and/or thrombectomy. Moreover, MR imaging may help avoid hospital admissions for patients with stroke mimics, facilitate earlier discharge, and reduce overall hospital costs. MRI in the in-patient setting can help determine stroke etiology to aid in stroke prevention management upon discharge. Furthermore, early access to MRI in IS out-patients can aid in diagnosing, risk stratifying, and determining optimal management strategies for patients with a TIA or a minor stroke. Recent technological advances, particularly low-to-mid-field MR scanners, can improve access to MRI. These MR scanners provide faster protocols, cost-effectiveness, smaller footprints, safety, and lower power requirements. In conclusion, MRI use for IS treatment, management, and prevention is imperative and justifiable, and the latest technological advancements in MR scanners hold the potential to enhance access.

Mortality After Total Anterior Circulation Stroke: A 25-Year Observational Study.

BACKGROUND: Mortality remains a substantial problem after acute ischemic stroke, despite advances in acute stroke treatment over the past three decades. Mortality is particularly high among patients with Total Anterior Circulation Stroke (TACS), generally representing patients with middle cerebral artery occlusions. Notably however, these patients also stand to benefit most from new therapies including endovascular thrombectomy (EVT). In this study, we aimed to examine temporal trends in, and factors associated with, 30-day in-hospital mortality after TACS. METHODS: Information on all patients with community-onset TACS from 1994 through 2019 was extracted from a prospective acute stroke registry. Multivariate analysis was performed on the primary outcome of 30-day in-hospital mortality, as well as secondary functional outcomes. RESULTS: We studied 1106 patients hospitalized for community-onset TACS, 456 (41%) of whom experienced 30-day in-hospital mortality. Over the 25 years of observation, 30-day in-hospital mortality rose and then fell. Increased odds of mortality was associated with age and stroke severity. Decreased odds of mortality was associated with alteplase therapy and EVT, as well as presentation to hospital more than 12 hours after stroke onset. Treatment with alteplase, EVT, or both was associated with higher odds of functional independence and discharge home, and shorter lengths of stay in acute care. CONCLUSIONS: Patients receiving alteplase, EVT, or both had lower 30-day in-hospital mortality and better functional outcomes than those who were untreated. These observational data demonstrate the benefits of recanalization therapy in routine clinical practice.

Dose-dependent effect of retrieval-extinction on preventing reinstatement of cocaine-associated memory in mice.

As a noninvasive behavioral intervention, the retrieval-extinction (R-E) procedure has drawn much research attention for its capacity to target the reconsolidation of maladaptive memories. However, later research findings suggest that the cause and consequence of R-E may be more complicated than previously suggested. For example, the R-E procedure could increase an animal's motivation for drug-seeking under certain circumstances, and the reversed extinction-retrieval (E-R) procedure could also suppress the drug memory. Two possible mechanisms underlying the R-E procedure have been proposed: the reconsolidation-update and extinction-facilitation hypotheses. To elucidate the paradoxical prior findings and examine these two hypotheses, we systematically examined the efficacy of the extinction (E), R-E, and E-R procedures in mice's low-dose versus high-dose cocaine-induced conditioned place preference (CPP) memory. We showed that the dose of cocaine is a crucial determinant of the efficacy of the three behavioral interventions. The E procedure exerted a long-lasting suppression of the low-dose cocaine CPP memory, while the R-E procedure induced more memory defects than the E and E-R procedures in its long-term suppression of the high-dose cocaine CPP memory. It warrants further investigation of whether the R-E procedure's underlying neurochemical and molecular mechanisms differ from the E and E-R procedures.

Sex differences in cocaine-associated memory: The interplay between CB1, mGluR5, and estradiol.

We know surprisingly little about the sex differences in the neurobiology of cocaine addiction, except females are more susceptible to the rewarding effects of cocaine than their male counterparts. Only a handful of recent studies have examined the neurobiology of cocaine-induced conditioned place preference (CPP) memory among female rodents. We contribute to this emerging line of research by documenting sex differences in cocaine-associated memory and illustrating the underlying signaling pathways in five experiments. Rimonabant (Rim), a cannabinoid CB1 antagonist and inverse agonist, exerted a facilitating effect for low-dose cocaine and an impairing effect for high-dose cocaine CPP memory in male mice, as in our previous study, but not in female mice. Nor did we observe the effect exist among CB1 knockout male mice, which indicated that the CB1 receptors played a mediating role. We also found that the metabotropic glutamate receptor 5 (mGluR5) was located in the same signaling pathway as CB1 in male mice. To clarify the mechanisms behind the sex differences, we used ovariectomized (OVX) female mice with estradiol benzoate (EB) replacement. In the OVX female mice, we showed that Rim-alone and EB-alone, but not Rim-and-EB-combined, facilitated the low-dose cocaine CPP memory. Moreover, 4-hydroxytamoxifen (4-OHT), an estrogen receptor (ER) antagonist, blocked Rim's and EB's facilitating effect. Finally, 2-methyl-6-(phenylethynyl)pyridine (MPEP), an mGluR5 antagonist, partially blocked EB's facilitating effect. In sum, we identified sex-specific effects of Rim on cocaine-induced CPP memory and the respective signaling pathways: mGluR5-CB1 for male mice and ER-mGluR5-CB1 for female mice. These findings may have merits for the development of sex-specific treatment for cocaine addiction.

Rottlerin, BDNF, and the impairment of inhibitory avoidance memory.

RATIONALE AND OBJECTIVE: As a eukaryotic elongation factor 2 kinase (eEF2K) inhibitor and a mitochondrial uncoupler, oncologists have extensively studied rottlerin. Neuroscientists, however, have accumulated scarce data on the role of rottlerin in affective and cognitive functions. Only two prior studies have, respectively, documented its antidepressant-like effect and how it impairs psychostimulant-supported memory. Whether or not rottlerin would affect aversive memory remains unknown. Hence, we sought to investigate the effects of rottlerin on aversive memory in the inhibitory avoidance (IA) task in mice. MATERIALS AND METHODS: Male C57BL/6J mice were trained to acquire the IA task. Rottlerin (5 mg/kg, i.p. or 3 µg bilaterally in the hippocampus) or the vehicle was administered before footshock training (acquisition), after footshock training (consolidation), after the memory reactivation (reconsolidation), and before the test (retrieval) in the IA task. RESULTS: Systemic and intrahippocampal rottlerin impaired the acquisition, consolidation, and retrieval of IA memory, without affecting the reconsolidation process. Rottlerin (5 mg/kg, i.p.) induced a fast-onset and long-lasting increase in the brain-derived neurotrophic factor (BDNF) protein levels in the mouse hippocampus. Systemic injection of 7,8-dihydroxyflavone (7,8-DHF, 30 mg/kg), a BDNF tropomyosin receptor kinase B (TrkB) agonist impaired IA memory consolidation, and treatment with K252a (5 µg/kg), a Trk receptor antagonist, reversed the suppressing effect of rottlerin on IA memory consolidation. CONCLUSION: Rottlerin impairs IA memory consolidation through the enhancement of BDNF signaling in the mouse hippocampus. Excessive brain BDNF levels can be detrimental to cognitive function. Rottlerin is likely to affect the original memory-associated neuroplasticity. Thus, it can be combined with exposure therapy to facilitate the forgetting of maladaptive aversive memory, such as post-traumatic stress disorder (PTSD).

The facilitating effect of MK-801 on inhibitory avoidance memory via mTOR signaling in the mouse hippocampus.

Despite the widespread belief that MK-801 induces memory deficits associated with dementia and schizophrenia in animal models, data regarding the impairing effect of MK-801 on aversive memory have been inconclusive. In this study, we investigated the effect of MK-801 on multiple memory stages of the inhibitory avoidance task, as well as its underlying signaling mechanism in the mouse hippocampus. We successfully replicated a previous finding suggesting that systemic injection of MK-801 impaired memory acquisition, but we observed that an intrahippocampal infusion of MK-801 facilitated the same memory process. We also found that both systemic and intrahippocampal administration of MK-801 facilitated memory consolidation and memory retrieval of the inhibitory avoidance task. We demonstrated that MK-801-induced increases in shock sensitivity and locomotor activity in the pre-training regimen confounded the detrimental effect of MK-801 on memory acquisition, thereby reconciling the inconsistent results in previous studies. In addition, the memory-facilitating effect of MK-801 was found to be dependent on drug dose and shock intensity. We next showed that MK-801 induced a fast-onset increase in the extent of mammalian target of rapamycin (mTOR) phosphorylation in the hippocampus. Finally, we observed that rapamycin, an mTOR inhibitor, blocked both the MK-801-induced increases in phosphorylated mTOR and the facilitating effect of MK-801 on memory consolidation. These results indicate that hippocampal mTOR signaling mediates the facilitating effect of MK-801 on memory consolidation of the inhibitory avoidance task. These findings further imply that MK-801 indeed functions as a memory enhancer and that mTOR signaling serves as a therapeutic target for memory disorders.

Endovascular Thrombectomy for Stroke Effectiveness Study-An Audit From a Small Tertiary Care Center.

PURPOSE: Endovascular thrombectomy (EVT) treatment for acute ischemic stroke is now recommended as a standard of care. However, implementing EVT in routine clinical practice poses many challenges, even in countries with advanced health-care systems. The aim of the current study is to delineate if EVT at our institution is an effective treatment for acute ischemic stroke. METHODS: All patients who underwent EVT at our institution between December 2011 and July 2017 were retrospectively assessed from our prospective registry. Clinical and imaging (including the Alberta Stroke Program Early CT [ASPECT] score, single-phase computed tomography angiography, and computed tomography perfusion) criteria were utilized to determine EVT suitability. Primary outcomes included modified Rankin score (mRS) at 90 days and recanalization determined by the modified Treatment in Cerebral Infarction score. Effectiveness was assessed by comparing our cohort with patients receiving EVT in the ESCAPE (Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke) trial. RESULTS: Eighty-eight patients presented to our hospital after a median of 87 minutes last seen normal. Of these, median ASPECT score was 9. A majority (72%) also received intravenous alteplase. Successful recanalization (≥TICI 2b) was achieved in 79%. At 90 days, 48% (36/75) were functionally independent (mRS score of 0-2) and 28% (21/75) were disabled (mRS score of 3-5); 24% (18/75) died (mRS of 6) within 90 days. CONCLUSIONS: An audit of our initial experience with EVT for the treatment of acute ischemic stroke in a small tertiary care center yielded similar results compared to the ESCAPE trial, which is encouraging for implementing this treatment in routine clinical practice.

Case-Control Study of Endovascular Thrombectomy in a Canadian Stroke Center.

BACKGROUND: Although the efficacy of endovascular thrombectomy (EVT) for acute ischemic stroke caused by intracranial anterior circulation large vessel occlusion (LVO) is proven, demonstration of local effectiveness is critical for health system planning and resource allocation because of the complexity and cost of this treatment. METHODS: Using our prospective registry, we identified all patients who underwent EVT for out-of-hospital LVO stroke from February 1, 2013 through January 31, 2017 (n = 44), and matched them 1:1 in a hierarchical fashion with control patients not treated with EVT based on age (±5 years), prehospital functional status, stroke syndrome, severity, and thrombolysis administration. Demographics, in-hospital mortality, discharge disposition from acute care, length of hospitalization, and functional status at discharge from acute care and at follow-up were compared between cases and controls. RESULTS: For EVT-treated patients (median age 66, 50% women), the median onset-to-recanalization interval was 247 min, and successful recanalization was achieved in 30/44 (91%). Alteplase was administered in 75% of cases and 57% of controls (p = 0.07). In-hospital mortality was 11% among the cases and 36% in the control group (p = 0.006); this survival benefit persisted during follow-up (p = 0.014). More EVT patients were discharged home from acute care (50% vs. 18%, p = 0.002). Among survivors, there were nonsignificant trends in favor of EVT for median length of hospitalization (14 vs. 41 days, p = 0.11) and functional independence at follow-up (51% vs. 32%, p = 0.079). CONCLUSION: EVT improved survival and decreased disability. This demonstration of single-center effectiveness may help facilitate expansion of EVT services in similar health-care jurisdictions.

Étude cas-témoin portant sur la thrombectomie endovasculaire dans un centre canadien de prise en charge des AVC. Contexte : Bien qu'on ait prouvé l'efficacité de la thrombectomie endovasculaire dans le cas d'accidents ischémiques cérébraux aigus causés par l'occlusion de grosses artères affectant la circulation antérieure intracrânienne, la démonstration de son efficacité sur le terrain est essentielle à la planification du réseau la santé et à l'allocation des ressources en raison de la complexité de ce traitement et des coûts qui y sont associés. Méthodes : À l'aide d'un registre prospectif, nous avons identifié tous les patients ayant bénéficié (n = 44), du 1er février 2013 au 31 janvier 2017, d'une thrombectomie endovasculaire à la suite d'un AVC survenu en dehors d'un établissement de la santé, AVC causé par l'occlusion de grosses artères. De manière hiérarchique, nous avons fait correspondre nos patients dans un rapport de 1 à 1 à nos témoins non traités par thrombectomie endovasculaire, et ce, en nous basant sur leur âge (± 5 ans), sur leur situation fonctionnelle avant d'être admis, sur les signes cliniques et la gravité de leur AVC, et sur l'administration d'un traitement thrombolytique. Nous avons également comparé leurs caractéristiques démographiques, leur taux de mortalité hospitalière, les modalités d'obtention d'un congé des soins intensifs, la durée de leur hospitalisation et leur situation fonctionnelle au moment de quitter les soins intensifs et à l'occasion d'un suivi. Résultats : Dans le cas de nos patients traités par thrombectomie endovasculaire (âge médian : 66 ans ; 50 % de femmes), l'intervalle médian entre les premiers signes d'un AVC et la recanalisation a été de 247 minutes. Fait à souligner, une recanalisation réussie a été accomplie dans 30 cas sur 44 (91 %). L'altéplase a été administré dans 75 % des cas et chez 57 % des témoins (p = 0,07). En ce qui concerne le taux de mortalité hospitalière, il a été de 11 % parmi tous nos cas et de 36 % chez nos témoins (p = 0,006) ; À noter que cet avantage en termes de survie a persisté au moment des suivis (p = 0,014). Plus de patients traités par thrombectomie endovasculaire ont obtenu leur congé des soins intensifs et sont revenus à la maison (50 % contre 18 % ; p = 0,002). Parmi les survivants à ces AVC, on a noté des tendances non significatives en faveur des patients traités par thrombectomie endovasculaire pour ce qui est de la durée médiane d'hospitalisation (14 jours contre 41 jours ; p = 0,11) et de l'autonomie fonctionnelle au moment des suivis (51 % contre 32 % ; p = 0,079). Conclusion : En somme, la thrombectomie endovasculaire a permis d'améliorer le taux de survie des patients ainsi que leur niveau d'autonomie fonctionnelle. Effectuée dans un seul établissement hospitalier, cette démonstration de l'efficacité de ce traitement pourrait contribuer à faciliter l'essor des traitements de thrombectomie endovasculaire dans d'autres systèmes de santé similaires.

A Cost-Utility Analysis of Endovascular Thrombectomy in a Real-World Setting.

OBJECTIVE: Endovascular thrombectomy (EVT) is efficacious for ischemic stroke caused by proximal intracranial large-vessel occlusion involving the anterior cerebral circulation. However, evidence of its cost-effectiveness, especially in a real-world setting, is limited. We assessed whether EVT ± tissue plasminogen activator (tPA) was cost-effective when compared with standard care ± tPA at our center. METHOD: We identified patients treated with EVT ± tPA after the Endovascular treatment for Small Core and Anterior circulation Proximal occlusion with Emphasis on minimizing computed tomography to recanalization times trial from our prospective stroke registry from February 1, 2013 to January 31, 2017. Patients admitted before February 2013 and treated with standard care ± tPA constitute the controls. The sample size was 88. Cost-effectiveness was assessed using the net monetary benefit (NMB). Differences in average costs and quality-adjusted life years (QALYs) were estimated using the augmented inverse probability weighted estimator. We accounted for sampling and methodological uncertainty in sensitivity analyses. RESULTS: Patients treated with EVT ± tPA had a net gain of 2.89 [95% confidence interval (CI): 0.93-4.99] QALYs at an additional cost of $22,200 (95% CI: -28,902-78,244) per patient compared with the standard care ± tPA group. The NMB was $122,300 (95% CI: -4777-253,133) with a 0.85 probability of being cost-effective. The expected savings to the healthcare system would amount to $321,334 per year. CONCLUSION: EVT ± tPA had higher costs and higher QALYs compared with the control, and is likely to be cost-effective at a willingness-to-pay threshold of $50,000 per QALY.

Analyse coût-efficacité de la thrombectomie endovasculaire dans un contexte réel. Objectif : La thrombectomie endovasculaire (TE) est efficace dans le cas d'accidents ischémiques cérébraux (AIC) causés par une occlusion proximale de l'artère cérébrale antérieure. Toutefois, les preuves d'un bon rapport coût-efficacité, particulièrement dans le cadre d'une pratique réelle, demeurent limitées. Nous avons ainsi évalué au sein de notre établissement dans quelle mesure la thrombectomie endovasculaire jumelée à un traitement au moyen d'un activateur tissulaire du plasminogène (t-PA) étaient davantage rentables en comparaison avec des soins usuels également jumelés à un traitement de t-PA. Méthodes : En consultant nos registres prospectifs, nous avons identifié des patients traités par une thrombectomie endovasculaire jumelée à un traitement de t-PA après avoir subi, du 1er février 2013 au 31 janvier 2017, un traitement endovasculaire destiné à un petit AVC central et ischémique à occlusion proximale avec un accent mis sur la minimisation du temps de recanalisation par tomodensitométrie. Les patients hospitalisés avant février 2013 et auxquels des soins usuels avaient été prodigués de concert avec l'administration d'un t-PA ont fait partie de notre groupe témoin. Au total, notre échantillon était formé de 88 patients. Nous avons évalué le rapport coût-efficacité au moyen du concept d'avantage monétaire net (AMN). Nous avons également estimé les différences en ce qui concerne les coûts moyens et l'indicateur QALY (quality-adjusted life years) en faisant appel à un estimateur pondéré par l'inverse de la probabilité inverse (augmented inverse probability weighted estimator). Enfin, nous avons tenu compte de l'incertitude de notre échantillonnage et de nos choix méthodologiques dans nos analyses de sensibilité. Résultats : Les patients traités par thrombectomie endovasculaire et l'administration d'un t-PA ont donné à voir un gain net de 2,89 années selon l'indicateur QALY (IC 95 % : 0,93 ­ 4,99) pour un coût additionnel de 22 200 $ (IC 95 % : −28,902 ­ 78,244) par patient si on les compare à notre groupe témoin. L'AMN s'est quant à lui élevé à 122 300 $ (IC 95 % : −4 777 ­ 253 133), sa probabilité d'être rentable atteignant 0,85. À cet égard, les économies annuelles pour le système de soins de santé pourraient atteindre les 321 334 $. Conclusion : Il appert que la thrombectomie endovasculaire jumelée à un traitement de t-PA entraînent des coûts plus élevés et un meilleur indicateur QALY en comparaison avec notre groupe témoin. Il est probable qu'une telle approche soit rentable en vertu d'un seuil de disposition à payer (willingness-to-pay threshold) avoisinant les 50 000 $ par année selon le QALY.

Cannabinoid receptor-mediated modulation of inhibitory inputs to mitral cells in the main olfactory bulb.

The endocannabinoid (eCB) signaling system has been functionally implicated in many brain regions. Our understanding of the role of cannabinoid receptor type 1 (CB1) in olfactory processing remains limited. Cannabinoid signaling is involved in regulating glomerular activity in the main olfactory bulb (MOB). However, the cannabinoid-related circuitry of inputs to mitral cells in the MOB has not been fully determined. Using anatomical and functional approaches we have explored this question. CB1 was present in periglomerular processes of a GAD65-positive subpopulation of interneurons but not in mitral cells. We detected eCBs in the mouse MOB as well as the expression of CB1 and other genes associated with cannabinoid signaling in the MOB. Patch-clamp electrophysiology demonstrated that CB1 agonists activated mitral cells and evoked an inward current, while CB1 antagonists reduced firing and evoked an outward current. CB1 effects on mitral cells were absent in subglomerular slices in which the olfactory nerve layer and glomerular layer were removed, suggesting the glomerular layer as the site of CB1 action. We previously observed that GABAergic periglomerular cells show the inverse response pattern to CB1 activation compared with mitral cells, suggesting that CB1 indirectly regulates mitral cell activity as a result of cellular activation of glomerular GABAergic processes . This hypothesis was supported by the finding that cannabinoids modulated synaptic transmission to mitral cells. We conclude that CB1 directly regulates GABAergic processes in the glomerular layer to control GABA release and, in turn, regulates mitral cell activity with potential effects on olfactory threshold and behavior.NEW & NOTEWORTHY Cannabinoid signaling with cannabinoid receptor type 1 (CB1) is involved in the regulation of glomerular activity in the main olfactory bulb (MOB). We detected endocannabinoids in the mouse MOB. CB1 was present in periglomerular processes of a GAD65-positive subpopulation of interneurons. CB1 agonists activated mitral cells. CB1 directly regulates GABAergic processes to control GABA release and, in turn, regulates mitral cell activity with potential effects on olfactory threshold and behavior.

Evidence for a GPR18 Role in Chemotaxis, Proliferation, and the Course of Wound Closure in the Cornea.

PURPOSE: We previously showed that cannabinoid-related GPR18 receptors are present in the murine corneal epithelium, but their function remains unknown. The related CB1 receptors regulate corneal healing, possibly via chemotaxis. We therefore examined a potential role for GPR18 in corneal epithelial chemotaxis and wound healing. METHODS: We examined GPR18 messenger RNA (mRNA) and protein expression in the cornea. We additionally examined GPR18 action in cultured bovine corneal epithelial cells (bCECs) using Boyden and tracking assays, as well as proliferation and signaling. Finally, we examined wound closure in murine corneal explants. RESULTS: GPR18 mRNA was upregulated with injury in the mouse cornea. GPR18 protein was present in basal epithelial cells of the mouse and cow and redistributed to the wound site upon injury. GPR18 ligand N-arachidonoylglycine induced bCEC chemotaxis. The endocannabinoid arachidonoylethanolamine also induced chemotaxis via fatty acid amide hydrolase-mediated metabolism to N-arachidonoylglycine. GPR18 receptor activation additionally induced bCEC proliferation. In an explant model, the GPR18 antagonist O-1918 slowed corneal epithelial cell migration and the rate of corneal wound closure. CONCLUSIONS: Corneal GPR18 activation induced both chemotaxis and proliferation in corneal epithelial cells in vitro and impacted wound healing. GPR18 may contribute to the maintenance of corneal integrity.

A GPR119 Signaling System in the Murine Eye Regulates Intraocular Pressure in a Sex-Dependent Manner.

Purpose: GPR119 is a G protein-coupled receptor that may be the endogenous target for 2-oleoylglycerol (2-OG), a lipid related to the endocannabinoid family of neuromodulators. Interest in GPR119 has centered on its role in regulating insulin secretion; however, the role of GPR119 has not been examined in the eye. The purpose of this study was to explore a potential GPR119-based signaling system in the murine eye. Methods: We used a combination of RT-PCR, immunohistochemistry, lipid measurement, and IOP measurement in a normotensive mouse model, with GPR119 knockout mice as controls. Results: We detected GPR119 mRNA and protein in the anterior eye of the mouse and cow, with GPR119 mRNA levels elevated in female relative to male mice. GPR119 protein expression is most prominent in structures near the angle, including trabecular meshwork, as well as iris and corneal epithelium. We detected 2-OG in the anterior eye and detected alterations in lipid levels in GPR119 knockout versus wild type and also by sex. Last, we found that 2-OG preferentially reduces IOP in female mice in a normotensive model. Conclusions: In summary, we offer evidence for a GPR119-based signaling system in the mammalian eye, with receptors, ligands, and function in the form of a reduction in IOP. Notably this reduction in pressure is restricted to female mice.

Harnessing the Endocannabinoid 2-Arachidonoylglycerol to Lower Intraocular Pressure in a Murine Model.

PURPOSE: Cannabinoids, such as Δ9-THC, act through an endogenous signaling system in the vertebrate eye that reduces IOP via CB1 receptors. Endogenous cannabinoid (eCB) ligand, 2-arachidonoyl glycerol (2-AG), likewise activates CB1 and is metabolized by monoacylglycerol lipase (MAGL). We investigated ocular 2-AG and its regulation by MAGL and the therapeutic potential of harnessing eCBs to lower IOP. METHODS: We tested the effect of topical application of 2-AG and MAGL blockers in normotensive mice and examined changes in eCB-related lipid species in the eyes and spinal cord of MAGL knockout (MAGL-/-) mice using high performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). We also examined the protein distribution of MAGL in the mouse anterior chamber. RESULTS: 2-Arachidonoyl glycerol reliably lowered IOP in a CB1- and concentration-dependent manner. Monoacylglycerol lipase is expressed prominently in nonpigmented ciliary epithelium. The MAGL blocker KML29, but not JZL184, lowered IOP. The ability of CB1 to lower IOP is not desensitized in MAGL-/- mice. Ocular monoacylglycerols, including 2-AG, are elevated in MAGL-/- mice but, in contrast to the spinal cord, arachidonic acid and prostaglandins are not changed. CONCLUSIONS: Our data confirm a central role for MAGL in metabolism of ocular 2-AG and related lipid species, and that endogenous 2-AG can be harnessed to reduce IOP. The MAGL blocker KML29 has promise as a therapeutic agent, while JZL184 may have difficulty crossing the cornea. These data, combined with the relative specificity of MAGL for ocular monoacylglycerols and the lack of desensitization in MAGL-/- mice, suggest that the development of an optimized MAGL blocker offers therapeutic potential for treatment of elevated IOP.

Rottlerin impairs the formation and maintenance of psychostimulant-supported memory.

RATIONALE AND OBJECTIVE: Since brain proteins such as protein kinase C (PKC), brain-derived neurotrophic factor (BDNF), and mammalian target of rapamycin (mTOR) are involved in the establishment and maintenance of psychostimulant memory, we sought to determine if systemic treatment with rottlerin, a natural compound affecting all these proteins, may modulate stimulant-supported memory. MATERIALS AND METHODS: Stimulant-induced conditioned place preference (CPP) was used in modeling stimulant-supported memory. RESULTS: Three cocaine (10 mg/kg; COC) or three methamphetamine (1 mg/kg; MA) conditioning trials reliably established the drug-induced CPP in male C57BL/6 mice. An intra-peritoneal rottlerin injection (5 mg/kg) at least 24 h prior to the first COC or first MA conditioning trial prevented the establishment of CPP. Following the establishment of the COC- or MA-induced CPP, saline conditioning trial was used to extinguish the CPP. Rottlerin (5 mg/kg, intra-peritoneal (i.p.)) administered 20 h prior to the first saline conditioning trial diminished subsequent drug- and stressor-primed reinstatement of the extinguished CPP. Rottlerin (5 mg/kg, i.p.) produced a fast-onset and long-lasting increase in hippocampal BDNF levels. However, treatment with a BDNF tropomyosin receptor kinase B (TrkB) receptor antagonist, K252a (5 µg/kg), did not affect rottlerin's suppressing effect on COC-induced CPP and treatment with 7,8-dihydroxyflavone (10 mg/kg x 6, 7,8-DHF), a selective TrkB agonist, prior to each conditioning trial did not affect COC-induced CPP. CONCLUSION: These results suggest that systemic rottlerin treatment may impair the formation of COC- and MA-supported memory. Importantly, such a treatment may advance our understanding of the underlying mechanism through which extinction training resulted in the "forgetting" of the COC- and MA-supported memory.

Involvement of TRPV1 in the Olfactory Bulb in Rimonabant-Induced Olfactory Discrimination Deficit.

Rimonabant is well recognized as a cannabinoid CB1 receptor antagonist/inverse agonist. Rimonabant not only antagonizes the effects induced by exogenous cannabinoids and endocannabinoids at CB1 receptors, it also exerts several pharmacological and behavioral effects independent of CB1 receptor inactivation. For example, rimonabant can function as a low-potency mixed agonist/antagonist of the transient receptor potential vanilloid receptor 1 (TRPV1). Hence, it is important to explain the underlying mechanisms of the diverse physiological effects induced by rimonabant with caution. Interestingly, CB1 receptor has recently been suggested to play a role in olfactory functions. Olfaction not only is involved in food intake, visual perception and social interaction, but also is proposed as a putative marker for schizophrenia and autism. Therefore, the present study aimed to investigate whether CB1 receptor and TRPV1 played a role in olfactory functions. We first used the genetic disruption approach to examine the role of CB1 receptor in olfactory functions and found that CB1 knockout mice exhibited olfactory discrimination deficit. However, it is important to point out that these CB1 knockout mice, despite their normal locomotivity, displayed deficiencies in the olfactory foraging and novel object exploration tasks. These results imply that general exploratory behaviors toward odorant and odorless objects are compromised in CB1 knockout mice. We next turned to the pharmacological approach to examine the role of CB1 receptor and TRPV1 in olfactory functions. We found that the short-term administration of rimonabant, injected systemically or directly into the olfactory bulb (OB), impaired olfactory discrimination that was rescued by the TRPV1 antagonist capsazepine (CPZ), via the same route of rimonabant, in wild-type mice. These results suggest that TRPV1 in the OB is involved in rimonabant-induced olfactory discrimination deficit. However, the rimonabant and/or CPZ treatments neither affected locomotivity nor general exploratory behaviors in wild-type mice. Finally, the acute systemic administration of rimonabant, unlike the short-term administration regimen, did not affect olfactory discrimination. Taken together, this study not only is the first one, to the best of our knowledge, suggests that the olfactory TRPV1 plays a role in olfactory functions, but also provides a possible mechanism for the olfactory discrimination deficit induced by rimonabant.

Patient perspectives of methadone formulation change in British Columbia, Canada: outcomes of a provincial survey.

BACKGROUND: In British Columbia, Canada, methadone maintenance treatment formulation transitioned from the oral liquid compound Tang™-flavoured methadone to the ten-times more concentrated cherry-flavoured Methadose™ in February 2014. We quantitatively describe perceptions and reported consequences among a sample of patients on methadone maintenance treatment following this transition. METHODS: A province-wide survey was used. Bivariable analyses utilized independent samples t-tests, Phi associations, and Chi-square tests. Multivariable logistic regression analyses evaluated factors related to dependent variables - namely, increases in dose, pain, dope sickness, and the need to supplement with additional opioids. RESULTS: Four hundred five methadone maintenance treatment patients from fifty harm reduction sites across British Columbia reported transitioning to Methadose™ in February 2014. The majority (n = 258; 73.1 %) heard about the formulation change from their methadone provider or pharmacist. Adjusted models show worse taste was positively associated with reporting an increasing dose (OR = 2.46; CI:1.31-4.61), feeling more dope sick (OR = 3.39; CI:1.88-6.12), and worsening pain (OR = 4.65; CI:2.45-8.80). Feeling more dope sick was positively associated with dose increase (OR = 2.24; CI:1.37-3.66), and supplementing with opioids (OR = 8.81; CI:5.16-15.05). CONCLUSIONS: Methadone maintenance treatment policy changes in British Columbia affect a structurally vulnerable population who may be less able to cope with transitions and loss of autonomy. There may be a psychosocial component contributing to the perception of Methadose™ tasting worse, and increased dope sickness, pain, and dose. Our study shows the pronounced negative impacts medication changes can have on patients without informed, coordinated efforts. We stress the need to engage all stakeholders allowing for communication about the reasons, risks and consequences of medication policy changes and provision of additional psychosocial support.

Quantification of type VI secretion system activity in macrophages infected with Burkholderia cenocepacia.

The Gram-negative bacterial type VI secretion system (T6SS) delivers toxins to kill or inhibit the growth of susceptible bacteria, while other secretion systems target eukaryotic cells. Deletion of atsR, a negative regulator of virulence factors in B. cenocepacia K56-2, increases T6SS activity. Macrophages infected with a K56-2 ΔatsR mutant display dramatic alterations in their actin cytoskeleton architecture that rely on the T6SS, which is responsible for the inactivation of multiple Rho-family GTPases by an unknown mechanism. We employed a strategy to standardize the bacterial infection of macrophages and densitometrically quantify the T6SS-associated cellular phenotype, which allowed us to characterize the phenotype of systematic deletions of each gene within the T6SS cluster and ten vgrG genes in K56-2 ΔatsR. None of the genes from the T6SS core cluster nor the individual vgrG genes were directly responsible for the cytoskeletal changes in infected cells. However, a mutant strain with all vgrG genes deleted was unable to cause macrophage alterations. Despite not being able to identify a specific effector protein responsible for the cytoskeletal defects in macrophages, our strategy resulted in the identification of the critical core components and accessory proteins of the T6SS assembly machinery and provides a screening method to detect T6SS effectors targeting the actin cytoskeleton in macrophages by random mutagenesis.