Stroke is a major global health problem. It is the third leading cause of death and the leading cause of adult disability. INTERHEART, a global case-control study of acute myocardial infarction in 52 countries (29,972 participants), identified nine modifiable risk factors that accounted for >90% of population-attributable risk. However, traditional risk factors (e.g. hypertension, cholesterol) appear to exert contrasting risks for stroke compared with coronary heart disease, and the etiology of stroke is far more heterogeneous. In addition, our knowledge of risk factors for stroke in low-income countries is inadequate, where a very large burden of stroke occurs. Accordingly, a similar epidemiological study is required for stroke, to inform effective population-based strategies to reduce the risk of stroke. Methods: INTERSTROKE is an international, multicenter case-control study. Cases are patients with a first stroke within 72 h of hospital presentation in whom CT or MRI is performed. Proxy respondents are used for cases unable to communicate. Etiological and topographical stroke subtype is documented for all cases. Controls are hospital- and community-based, matched for gender, ethnicity and age (±5 years). A questionnaire (cases and controls) is used to acquire information on known and proposed risk factors for stroke. Cardiovascular (e.g. blood pressure) and anthropometric (e.g. waist-to-hip ratio) measurements are obtained at the time of interview. Nonfasting blood samples and random urine samples are obtained from cases and controls. Study Significance: An effective global strategy to reduce the risk of stroke mandates systematic measurement of the contribution of the major vascular risk factors within defined ethnic groups and geographical locations.

BackgroundMRI is a sensitive method for the assessment of brain abnormalities in Wilson disease, that is, T2 hyperintensities, T2 hypointensities, and atrophy, but a validated scoring system for the classification of radiological severity is lacking. The objective of this study was to develop and validate a brain MRI visual rating scale for Wilson disease.MethodsThe proposed Wilson disease brain MRI severity scale consists of acute toxicity and chronic damage subscores from predefined structures. The former, calculated by summing scores of T2 hyperintensities (excluding cavitation), is likely to be partially reversible with treatment. The latter, representing the sum of scores of T2 hypointensities and brain atrophy, reflects pathology that is not readily reversible. Validation was performed on MRI scans acquired using 1.5T system from 39 Wilson disease patients examined at baseline and after 24 months on anticopper treatment. Intraclass correlation coefficients of 5 ratings from 3 raters were calculated. Temporal evolution of the MRI severity score and its association with clinical severity, assessed using the Unified Wilson Disease Rating Scale part III, was calculated.ResultsIntrarater and interrater agreement were good (r > 0.93; P < 0.001; and r > 0.74; P < 0.001, respectively). In neurologic Wilson disease patients, the total MRI severity score improved over 2 years (P = 0.032), mainly because of reduced acute toxicity (P = 0.0015), whereas the chronic damage score deteriorated (P = 0.035). Unified Wilson Disease Rating Scale part III score was positively associated with chronic damage and total score at baseline (P = 0.005 and P = 0.003, respectively) and in month 24 (P < 0.001 and P = 0.001, respectively).ConclusionsThe Wilson disease brain MRI severity scale is a simple, reliable, and valid instrument that allows semiquantitative assessment of radiological Wilson disease severity. © 2020 International Parkinson and Movement Disorder Society

HIV-infected brains are characterized by increased amyloid beta (Aβ) deposition. It is believed that the blood-brain barrier (BBB) is critical for Aβ homeostasis and contributes to Aβ accumulation in the brain. Extracellular vesicles (ECV), like exosomes, recently gained a lot of attention as potentially playing a significant role in Aβ pathology. In addition, HIV-1 hijacks the exosomal pathway for budding and release. Therefore, we investigated the involvement of BBB-derived ECV in the HIV-1-induced Aβ pathology in the brain. Our results indicate that HIV-1 increases ECV release from brain endothelial cells as well as elevates their Aβ cargo when compared to controls. Interestingly, brain endothelial cell-derived ECV transferred Aβ to astrocytes and pericytes. Infusion of brain endothelial ECV carrying fluorescent Aβ into the internal carotid artery of mice resulted in Aβ fluorescence associated with brain microvessels and in the brain parenchyma. These results suggest that ECV carrying Aβ can be successfully transferred across the BBB into the brain. Based on these observations, we conclude that HIV-1 facilitates the shedding of brain endothelial ECV carrying Aβ; a process that may increase Aβ exposure of cells of neurovascular unit, and contribute to amyloid deposition in HIV-infected brain.

Ammonia is a neurotoxin involved in the pathogenesis of neurological conditions associated with hyperammonemia, including hepatic encephalopathy, a condition associated with acute—(ALF) or chronic liver failure. This article reviews evidence that apart from directly affecting the metabolism and function of the central nervous system cells, ammonia influences the passage of different molecules across the blood brain barrier (BBB). A brief description is provided of the tight junctions, which couple adjacent cerebral capillary endothelial cells to each other to form the barrier. Ammonia modulates the transcellular passage of low-to medium-size molecules, by affecting their carriers located at the BBB. Ammonia induces interrelated aberrations of the transport of the large neutral amino acids and aromatic amino acids (AAA), whose influx is augmented by exchange with glutamine produced in the course of ammonia detoxification, and maybe also modulated by the extracellularly acting gamma-glutamyl moiety transferring enzyme, gamma-glutamyl-transpeptidase. Impaired AAA transport affects neurotransmission by altering intracerebral synthesis of catecholamines (serotonin and dopamine), and producing “false neurotransmitters” (octopamine and phenylethylamine). Ammonia also modulates BBB transport of the cationic amino acids: the nitric oxide precursor, arginine, and ornithine, which is an ammonia trap, and affects the transport of energy metabolites glucose and creatine. Moreover, ammonia acting either directly or in synergy with liver injury-derived inflammatory cytokines also evokes subtle increases of the transcellular passage of molecules of different size (BBB “leakage”), which appears to be responsible for the vasogenic component of cerebral edema associated with ALF.

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Energetic regulation at the blood-brain barrier is critical for maintaining its integrity, transport capabilities, and brain demands for glucose. However, the underlying mechanisms that regulate these processes are still poorly explored. We recently characterized the protein occludin as a NADH oxidase and demonstrated its influence on the expression and activation of the histone deacetylase SIRT-1. Because SIRT-1 works in concert with AMP-activated protein kinase (AMPK) (AMPK), we investigated the impact of occludin on this metabolic switch. Here we show that in blood-brain barrier pericytes, occludin promotes AMPK expression and activation, influencing the expression of glucose transporters GLUT-1 and GLUT-4, glucose uptake, and ATP content. Furthermore, occludin expression, AMP-dependent protein kinase activity, and glucose uptake were altered under inflammatory (TNFα) and infectious (HIV) conditions. We also show that pericytes share glucose and mitochondria with astrocytes, and that occludin levels modify the ability of pericytes to share those energetic resources. In addition, we demonstrate that murine mitochondria can be transferred from live brain microvessels to energetically impaired human astrocytes, promoting their survival. Our findings demonstrate that occludin plays an important role in blood-brain barrier pericyte metabolism by influencing AMPK protein kinase activity, glucose uptake, ATP production, and by regulating the ability of pericytes to interact metabolically with astrocytes.

Ammonia is responsible for cerebral edema (CE) associated with acute liver failure (ALF), but the role of the vasogenic mechanism has been a matter of dispute. Here, we tested the hypothesis that ammonia induces changes in blood-brain barrier (BBB) permeability by a mechanism coupled to oxidative/ nitrosative stress (ONS) evoked in the BBB-forming cerebral capillary endothelial cells. Treatment of a rat brain endothelial cell line (RBE-4) with ammonia (5 mmol/L, 24h) caused accumulation of ONS markers: reactive oxygen species (ROS), nitric oxide (NO) and peroxidation products of phospholipid-bound arachidonic acid, F2-isoprostanes (F2-IsoPs). Concurrently, ammonia increased the activity of extracellular matrix metalloproteinases (MMP-2/MMP-9), increased cell permeability to fluorescein isothiocyanate (FITC)-dextran (40 kDa), and increased the expression of y+LAT2, a transporter that mediates the uptake to the cells of the NO precursor, arginine (Arg). The increase of cell permeability was ameliorated upon co-treatment with a MMP inhibitor, SB-3CT and with an antioxidant, glutathione diethyl ester (GEE), which also reduced F2-IsoPs. Ammonia-induced ONS was attenuated by cytoprotective agents L- ornithine (Orn), phenylbutyrate (PB), and their conjugate L-ornithine phenylbutyrate (OP), an ammonia-trapping drug used to treat hyperammonemia. The results support the concept that ONS and ONS-related activation of MMPs in cerebral capillary endothelial cells contribute to the alterations in BBB permeability and to the vasogenic component of CE associated with ALF.

HIV-1 infection and methamphetamine (METH) abuse frequently occur simultaneously and may have synergistic pathological effects. Although HIV-positive/active METH users have been shown to have higher HIV viral loads and experience more severe neurological complications than non-users, the direct impact of METH on HIV infection and its link to the development of neurocognitive alternations are still poorly understood. In the present study, we hypothesized that METH impacts HIV infection of neural progenitor cells (NPCs) by a mechanism encompassing NFκB/SP1-mediated HIV LTR activation. Mouse and human NPCs were infected with EcoHIV (modified HIV virus infectious to mice) and HIV, respectively, in the presence or absence of METH (50 or 100 μm). Pretreatment with METH, but not simultaneous exposure, significantly increased HIV production in both mouse and human NPCs. To determine the mechanisms underlying these effects, cells were transfected with different variants of HIV LTR promoters and then exposed to METH. METH treatment induced transcriptional activity of the HIV LTR promotor, an effect that required both NFκB and SP1 signaling. Pretreatment with METH also decreased neuronal differentiation of HIV-infected NPCs in both and settings. Importantly, NPC-derived daughter cells appeared to be latently infected with HIV. This study indicates that METH increases HIV infectivity of NPCs, through the NFκB/SP1-dependent activation of the HIV LTR and with the subsequent alterations of NPC neurogenesis. Such events may underlie METH- exacerbated neurocognitive dysfunction in HIV-infected patients.