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Dysfunctional endothelium is increasingly recognized as a mechanistic link between cardiovascular risk factors and dementia, including Alzheimer disease. BACE1 (β-site amyloid-β precursor protein-cleaving enzyme 1) is responsible for β-processing of APP (amyloid-β precursor protein), the first step in the production of Aβ (amyloid-β) peptides, major culprits in the pathogenesis of Alzheimer disease. Under pathological conditions, excessive activation of BACE1 exerts detrimental effects on endothelial function by Aβ-dependent and Aβ-independent mechanisms. High local concentration of Aβ in the brain blood vessels is responsible for the loss of key vascular protective functions of endothelial cells. More recent studies recognized significant contribution of Aβ-independent proteolytic activity of endothelial BACE1 to the pathogenesis of endothelial dysfunction. This review critically evaluates existing evidence supporting the concept that excessive activation of BACE1 expressed in the cerebrovascular endothelium impairs key homeostatic functions of the brain blood vessels. This concept has important therapeutic implications. Indeed, improved understanding of the mechanisms of endothelial dysfunction may help in efforts to develop new approaches to the protection and preservation of healthy cerebrovascular function., Competing Interests: None.

Revascularization and angiogenesis, as substrates of sustained collateral circulation, play a crucial role in determining the severity and clinical outcome of acute ischemic stroke (AIS) due to large vessel occlusion (LVO). Developing an adjunct biomarker to help identify and monitor collateral status would aid stroke diagnosis and prognosis. To screen the potential biomarkers, proteomic analysis was performed in this study to identify those distinct plasma protein profiles in AIS due to LVO with different collateral status. Interestingly, we found that levels of Plasma Factor VII Activating Protease (FSAP) significantly increased in those AIS patients with poor collaterals, and were correlated with worse neurological outcome. Furtherly, both in vitro and in vivo models of ischemic stroke were used to explore pathological mechanisms of FSAP in endothelial dysfunction. We demonstrated that the FSAP inhibitor, high-molecular-weight hyaluronan (HMW-HA), enhanced the pro-angiogenic vascular factors, improved the integrity of brain blood barrier, and promoted newly formed cerebral microvessels in the ischemic penumbra, consequently improving neurological function. To elucidate the pathways that might contribute to revascularization during LVO, we applied transcriptomic analysis via unbiased RNA sequencing and showed that Wnt signaling was highly involved in FSAP mediated endothelial dysfunction. Notably, inhibition of Wnt5a largely reversed the protective effects from HMW-HA treatment, implying that FSAP might aggravate endothelial dysfunction and neurological deficits by regulating Wnt5a signaling. Therefore, FSAP may represent a potential biomarker for collateral status after LVO and a promising therapeutic target to be explored in the treatment of stroke., (© 2021. The Author(s).)

Ischemic episodes are a leading cause of death worldwide with limited therapeutic interventions. The current study explored mitochondrial phosphate-activated glutaminase (GLS1) activity modulation by PKCβII through GC-MS untargeted metabolomics approach. Mitochondria were used to elucidate the endogenous resistance of hippocampal CA2-4 and dentate gyrus (DG) to transient ischemia and reperfusion in a model of ischemic episode in gerbils. In the present investigation, male gerbils were subjected to bilateral carotids occlusion for 5 min followed by reperfusion (IR). Gerbils were randomly divided into three groups as vehicle-treated sham control, vehicle-treated IR and PKCβII specific inhibitor peptide βIIV5-3-treated IR. Vehicle or βIIV5-3 (3 mg/kg, i.v.) were administered at the moment of reperfusion. The gerbils hippocampal tissue were isolated at various time of reperfusion and cell lysates or mitochondria were isolated from CA1 and CA2-4,DG hippocampal regions. Recombinant proteins PKCβII and GLS1 were used in in vitro phosphorylation reaction and organotypic hippocampal cultures (OHC) transiently exposed to NMDA (25 μM) to evaluate the inhibition of GLS1 on neuronal viability. PKCβII co-precipitates with GAC (GLS1 isoform) in CA2-4,DG mitochondria and phosphorylates GLS1 in vitro. Cell death was dose dependently increased when GLS1 was inhibited by BPTA while inhibition of mitochondrial pyruvate carrier (MPC) attenuated cell death in NMDA-challenged OHC. Fumarate and malate were increased after IR 1h in CA2-4,DG and this was reversed by βIIV5-3 what correlated with GLS1 activity increases and earlier showed elevation of neuronal death (Krupska et al., 2017). The present study illustrates that CA2-4,DG resistance to ischemic episode at least partially rely on glutamine and glutamate utilization in mitochondria as a source of carbon to tricarboxylic acid cycle. This phenomenon depends on modulation of GLS1 activity by PKCβII and remodeling of MPC: all these do not occur in ischemia-vulnerable CA1.

Background: Coronary artery disease (CAD) increases risk for vascular cognitive impairment-no dementia (VCIND), a precursor to dementia, potentially through persistent oxidative stress., Objective: This study assessed peripheral glutathione peroxidase activity (GPX), which is protective against oxidative stress, in VCIND versus cognitively normal CAD controls (CN). GPX activity was also evaluated as a biomarker of cognition, particularly verbal memory., Methods: 120 CAD patients with VCIND (1SD below norms on executive function or verbal memory (VM)) or without (CN) participated in exercise rehabilitation for 24 weeks. Neurocognitive and cardiopulmonary fitness (VO2peak) assessments and plasma were collected at baseline and 24-weeks., Results: GPX was higher in VCIND compared to CN (F1,119 = 3.996, p = 0.048). Higher GPX was associated with poorer baseline VM (β= -0.182, p = 0.048), and longitudinally with VM decline controlling for sex, body mass index, VO2peak, and education (b[SE] = -0.02[0.01], p = 0.004). Only CN participants showed improved VM performance with increased fitness (b[SE] = 1.30[0.15], p < 0.005)., Conclusion: GPX was elevated in VCIND consistent with a compensatory response to persistent oxidative stress. Increased GPX predicted poorer cognitive outcomes (verbal memory) in VCIND patients despite improved fitness.

While activation of cannabinoid (CB2) receptors has been shown to be neuroprotective, no studies have examined whether this neuroprotection is directed at cerebral arterioles and no studies have examined whether activation of CB2 receptors can rescue cerebrovascular dysfunction during a chronic disease state such as type 1 diabetes (T1D). Our goal was to test the hypothesis that administration of a CB2 agonist (JWH-133) would improve impaired endothelial (eNOS)- and neuronal (nNOS)-dependent dilation of cerebral arterioles during T1D. In vivo diameter of cerebral arterioles in nondiabetic and T1D rats was measured in response to an eNOS-dependent agonist (adenosine 5'-diphosphate; ADP), an nNOS-dependent agonist (N-methyl-d-aspartate; NMDA), and an NOS-independent agonist (nitroglycerin) before and 1 h following JWH-133 (1 mg/kg IP). Dilation of cerebral arterioles to ADP and NMDA was greater in nondiabetic than in T1D rats. Treatment with JWH-133 increased responses of cerebral arterioles to ADP and NMDA in both nondiabetic and T1D rats. Responses of cerebral arterioles to nitroglycerin were similar between nondiabetic and T1D rats, and JWH-133 did not influence responses to nitroglycerin in either group. The restoration in responses to the agonists by JWH-133 could be inhibited by treatment with a specific inhibitor of CB2 receptors (AM-630; 3 mg/kg IP). Thus, activation of CB2 receptors can potentiate reactivity of cerebral arterioles during physiologic and pathophysiologic states. We speculate that treatment with CB2 receptor agonists may have potential therapeutic benefits for the treatment of cerebral vascular diseases via a mechanism that can increase cerebral blood flow., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Oxidative stress caused by an imbalance in the formation and removal of reactive oxygen species (ROS) plays an important role in the development of several cardiovascular diseases. ROS originate from various cellular origins; however, the highest amount of ROS is produced by mitochondria. One of the proteins contributing to mitochondrial ROS formation is the adaptor protein p66shc, which upon cellular stresses translocates from the cytosol to the mitochondria. In the present review, we focus on the role of p66shc in longevity, in the development of cardiovascular diseases including diabetes, atherosclerosis and its risk factors, myocardial ischemia/reperfusion injury and the protection from it by ischemic preconditioning. Also, the contribution of p66shc towards cerebral pathologies and the potential of the protein as a therapeutic target for the treatment of the aforementioned diseases are discussed.

Over the past four decades, Alzheimer disease has become near synonymous with dementia and the amyloid/tau hypothesis as its dominant explanation. However, this monorail approach to etiology has failed to yield a single disease-modifying drug. Part of the explanation stems from the fact that most dementias in the elderly result from interactive Alzheimer and cerebrovascular pathologies. Stroke and dementia share the same risk factors and their control is associated with a decrease in stroke and some dementias. Additionally, intensive control of risk factors and enhancement of protective factors improve cognition. Moreover, anticoagulation of atrial fibrillation patients decreases their chance of developing dementia by 48%. Preliminary data suggest that treating blood pressure to a target of 120 mmHg systolic compared to a target of 140 mmHg decreases the chances of mild cognitive impairment by 19%. The Berlin Manifesto establishes the scientific bases of "preventing dementia by preventing stroke." Enlarging our vista of dementia to include cerebrovascular disease offers the opportunity of preventing not only stroke, but some dementias, beginning now.

Objective- Mitochondria are the important yet most underutilized target for cardio-cerebrovascular function integrity and disorders. The Tom (translocases of outer membrane) complex are the critical determinant of mitochondrial homeostasis for making organs acclimate physiological and pathological insults; however, their roles in the vascular system remain unknown. Approach and Results- A combination of studies in the vascular-specific transgenic zebrafish and genetically engineered mice was conducted. Vascular casting and imaging, endothelial angiogenesis, and mitochondrial protein import were performed to dissect potential mechanisms. A loss-of-function genetic screening in zebrafish identified that selective inactivation of the tomm7 (translocase of outer mitochondrial membrane 7) gene, which encodes a small subunit of the Tom complex, specially impaired cerebrovascular network formation. Ablation of the ortholog Tomm7 in mice recapitulated cerebrovascular abnormalities. Restoration of the cerebrovascular anomaly by an endothelial-specific transgenesis of tomm7 further indicated a defect in endothelial function. Mechanistically, Tomm7 deficit in endothelial cells induced an increased import of Rac1 (Ras-related C3 botulinum toxin substrate 1) protein into mitochondria and facilitated the mitochondrial Rac1-coupled redox signaling, which incurred angiogenic impairment that underlies cerebrovascular network malformation. Conclusions- Tomm7 drives brain angiogenesis and cerebrovascular network formation through modulating mitochondrial Rac1 signaling within the endothelium.

Progress in clinical development of magnetic resonance imaging (MRI) substrate-sensors of enzymatic activity has been slow partly due to the lack of human efficacy data. We report here a strategy that may serve as a shortcut from bench to bedside. We tested ultra high-resolution 7T MRI (µMRI) of human surgical histology sections in a 3-year IRB approved, HIPAA compliant study of surgically clipped brain aneurysms. µMRI was used for assessing the efficacy of MRI substrate-sensors that detect myeloperoxidase activity in inflammation. The efficacy of Gd-5HT-DOTAGA, a novel myeloperoxidase (MPO) imaging agent synthesized by using a highly stable gadolinium (III) chelate was tested both in tissue-like phantoms and in human samples. After treating histology sections with paramagnetic MPO substrate-sensors we observed relaxation time shortening and MPO activity-dependent MR signal enhancement. An increase of normalized MR signal generated by ultra-short echo time MR sequences was corroborated by MPO activity visualization by using a fluorescent MPO substrate. The results of µMRI of MPO activity associated with aneurysmal pathology and immunohistochemistry demonstrated active involvement of neutrophils and neutrophil NETs as a result of pro-inflammatory signalling in the vascular wall and in the perivascular space of brain aneurysms.

Background: Inconsistent conclusions have been reported for the genetic relationship between CYP4F2 (Cytochrome P450 Family 4 Subfamily F Member 2) polymorphisms and the susceptibility to cardiovascular and cerebrovascular diseases., Methods: We performed a meta-analysis to assess the potential role of rs1558139 C/T and rs2108622 G/A polymorphisms of CYP4F2 in the risks of cardiovascular and cerebrovascular diseases. The retrieval of four databases, including PubMed, Web of Science (WOS), China National Knowledge Infrastructure (CNKI) and WANFANG DATA, was conducted. Mantel-Haenszel statistics for association test, Cochran's Q statistic, sensitivity analysis for heterogeneity assessment, and Begg's/Egger's tests for publication bias evaluation were performed under allele, homozygote, heterozygote, dominant, and recessive models, respectively., Results: A total of 597 articles were initially obtained by database searching, and twenty eligible articles were finally included. For rs1558139, a decreased risk of cardiovascular and cerebrovascular diseases was observed in the overall meta-analysis and in "hypertension", "population-based" and "male" subgroups under models of T vs. C, CT vs. CC, and CT + TT vs. CC [all P values in association tests < 0.05, odds ratio (OR) < 1]. For rs2108622, a decreased coronary artery disease (CAD) risk was observed in the subgroup meta-analysis based on disease type under all genetic models (all P values in association tests < 0.05, OR< 1). Begg's/Egger's tests excluded the potential publication bias, while sensitivity analysis data supported the stability of the above results., Conclusion: C/T genotype of CYP4AF2 rs1558139 may be linked to the decreased risk of hypertension in the male patients of Asian populations, while CYP4F2 rs2108622 is likely associated with reduced susceptibility to CAD.

von Willebrand factor (VWF) is a key player in hemostasis, acting as a carrier for factor VIII and capturing platelets at sites of vascular damage. To capture platelets, it must undergo conformational changes, both within its A1 domain and at the macromolecular level through A2 domain unfolding. Its size and this function are regulated by the metalloproteinase ADAMTS-13. Recently, it has been shown that ADAMTS-13 undergoes a conformational change upon interaction with VWF, and that this enhances its activity towards its substrate. This review summarizes recent work on these conformational transitions, describing how they are controlled. It points to their importance in hemostasis, bleeding disorders, and the developing field of therapeutic application of ADAMTS-13 as an antithrombotic agent in obstructive microvascular thrombosis and in cardiovascular disease., (© 2017 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals, Inc. on behalf of International Society on Thrombosis and Haemostasis.)

TIGAR-regulated pentose phosphate pathway (PPP) plays a critical role in the neuronal survival during cerebral ischemia/reperfusion. Glucose-6-phosphate dehydrogenase (G6PD) is a rate-limiting enzyme in PPP and thus, we hypothesized that it plays an essential role in anti-oxidative defense through producing NADPH. The present study investigated the regulation and the role of G6PD in ischemia/reperfusion-induced neuronal injury with in vivo and in vitro models of ischemic stroke. The results showed that the levels of G6PD mRNA and protein were increased after ischemia/reperfusion. In vivo, lentivirus-mediated G6PD overexpression in mice markedly reduced neuronal damage after ischemia/reperfusion insult, while lentivirus-mediated G6PD knockdown exacerbated it. In vitro, overexpression of G6PD in cultured primary neurons decreased neuronal injury under oxygen and glucose deprivation/reoxygenation (OGD/R) condition, whereas knockdown of G6PD aggravated it. Overexpression of G6PD increased levels of NADPH and reduced form of glutathione (rGSH), and ameliorated ROS-induced macromolecular damage. On the contrary, knockdown of G6PD executed the opposite effects in mice and in primary neurons. Supplementation of exogenous NADPH alleviated the detrimental effects of G6PD knockdown, whereas further enhanced the beneficial effects of G6PD overexpression in ischemic injury. Therefore, our results suggest that G6PD protects ischemic brain injury through increasing PPP. Thus G6PD may be considered as potential therapeutic target for treatment of ischemic brain injury., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Events responsible for cerebrovascular disease in diabetes are not fully understood. Pericyte loss is an early event that leads to endothelial cell death, microaneurysms, and cognitive impairment. A biochemical mechanism underlying pericyte loss is rapid respiration (oxidative metabolism of glucose). This escalation in respiration results from free influx of glucose into insulin-insensitive tissues in the face of high glucose levels in the blood. Rapid respiration generates superoxide, the precursor to all reactive oxygen species (ROS), and results in pericyte death. Respiration is regulated by carbonic anhydrases (CAs) VA and VB, the two isozymes expressed in mitochondria, and their pharmacologic inhibition with topiramate reduces respiration, ROS, and pericyte death. Topiramate inhibits both isozymes; therefore, in the earlier studies, their individual roles were not discerned. In a recent genetic study, we showed that mitochondrial CA VA plays a significant role in regulation of reactive oxygen species and pericyte death. The role of CA VB was not addressed. In this report, genetic knockdown and overexpression studies confirm that mitochondrial CA VA regulates respiration in pericytes, whereas mitochondrial CA VB does not contribute significantly. Identification of mitochondrial CA VA as a sole regulator of respiration provides a specific target to develop new drugs with fewer side effects that may be better tolerated and can protect the brain from diabetic injury. Since similar events occur in the capillary beds of other insulin-insensitive tissues such as the eye and kidney, these drugs may also slow the onset and progression of diabetic disease in these tissues., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

Marfan syndrome (MFS) is a connective tissue disorder that is often associated with the fibrillin-1 (Fbn1) gene mutation and characterized by cardiovascular alterations, predominantly ascending aortic aneurysms. Although neurovascular complications are uncommon in MFS, the improvement in Marfan patients' life expectancy is revealing other secondary alterations, potentially including neurovascular disorders. However, little is known about small-vessel pathophysiology in MFS. MFS is associated with hyperactivated transforming growth factor (TGF)-β signaling, which among numerous other downstream effectors, induces the NADPH oxidase 4 (Nox4) isoform of NADPH oxidase, a strong enzymatic source of H2O2 We hypothesized that MFS induces middle cerebral artery (MCA) alterations and that Nox4 contributes to them. MCA properties from 3-, 6-, or 9-mo-old Marfan (Fbn1(C1039G/+)) mice were compared with those from age/sex-matched wild-type littermates. At 6 mo, Marfan compared with wild-type mice developed higher MCA wall/lumen (wild-type: 0.081 ± 0.004; Marfan: 0.093 ± 0.002; 60 mmHg; P < 0.05), coupled with increased reactive oxygen species production, TGF-β, and Nox4 expression. However, wall stiffness and myogenic autoregulation did not change. To investigate the influence of Nox4 on cerebrovascular properties, we generated Marfan mice with Nox4 deficiency (Nox4(-/-)). Strikingly, Nox4 deletion in Marfan mice aggravated MCA wall thickening (cross-sectional area; Marfan: 6,660 ± 363 μm(2); Marfan Nox4(-/-): 8,795 ± 824 μm(2); 60 mmHg; P < 0.05), accompanied by decreased TGF-β expression and increased collagen deposition and Nox1 expression. These findings provide the first evidence that Nox4 mitigates cerebral artery structural changes in a murine model of MFS., (Copyright © 2016 the American Physiological Society.)

Endothelial nitric oxide (NO) is a significant signaling molecule that regulates cerebral blood flow (CBF), playing a pivotal role in the prevention and treatment of cerebrovascular diseases. However, achieving the expected therapeutic efficacy is difficult using direct administration of NO donors. Therefore, endothelial nitric oxide synthase (eNOS) becomes a potential therapeutic target for cerebrovascular diseases. This review summarizes the current evidence supporting the importance of CBF to cerebrovascular function, and the roles of NO and eNOS in CBF regulation.

Vascular cognitive impairment (VCI) is a heterogeneous group of diseases linked together by cerebrovascular disease. Treatment of VCI has been hindered by the lack of a coherent pathophysiological process that could provide molecular targets. Of the several forms of VCI, the small vessel disease form is both the most prevalent and generally has a progressive course. Binswanger's disease (BD) is the small vessel form of VCI that involves extensive injury to the deep white matter. Growing evidence suggests that there is disruption of the blood-brain barrier (BBB) secondary to an inflammatory state. Matrix metalloproteinases (MMPs) are increased in the brain and CSF of patients with BD, and have been shown to disrupt the BBB in animal studies, suggesting that they may be biomarkers and therapeutic targets. Multimodal biomarkers derived from clinical, neuropsychological, imaging, and biochemical data can be used to narrow the VCI population to the progressive inflammatory form that will be optimal for treatment trials. This review describes the role of the MMPs in pathophysiology and their use as biomarkers.

The development of novel pharmaceutical treatments for disorders of the cerebral vasculature is a serious unmet medical need. These vascular disorders are typified by a disruption in the delicate Rho signaling equilibrium within the blood vessel wall. In particular, Rho kinase overactivation in the smooth muscle and endothelial layers of the vessel wall results in cytoskeletal modifications that lead to reduced vascular integrity and abnormal vascular growth. Rho kinase is thus a promising target for the treatment of cerebral vascular disorders. Indeed, preclinical studies indicate that Rho kinase inhibition may reduce the formation/growth/rupture of both intracranial aneurysms and cerebral cavernous malformations.

Alcohol abuse increases the incidence of cerebral accidents, which correlates with cerebrovascular structural changes. The present study was designed to observe the cerebrovascular remodeling of drinking rats with light microscopy and transmission electron microscopy (TEM). Short-term alcohol administration induced apparent amplification of perivascular spaces around small vessels in brain tissue, while long-term administration caused pathological changes of basilar arteries (BAs), including endothelial exfoliation, inner elastic lamina (IEL) fragmentation and thickening of tunica media and adventitia. In addition, the relationship between cerebrovascular remodeling and MMP-2 and MMP-9 synthesized by endothelial cells and vascular smooth muscle cells was explored by immunohistochemistry. The two protein expression in cerebral vessels changed dynamically, peaking at 1-2 weeks after treatment, and decreasing as treatment continued. These results suggest that MMP-2 and MMP-9 may play a significant role in blood-brain barrier disruption after alcohol abuse. But the chronic changes of cerebral arteries resulted from drinking are not coincident with time course of MMP-2 and MMP-9 expression in situ.

Herein, we report the biological evaluation of a series of indole substituted hydrazides and hydrazines throughout the assessment of their multipotent inhibitory potency towards monoamine oxidase (MAO) A and B, semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1), and the cholinesterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Hydrazine JL72 (3-(3-hydrazinylpropyl)-1H-indole) showed a potent, reversible and non-time-dependent inhibition of MAO-A, which suggests its capacity in restoring serotoninergic neurotransmission being devoid of the side effects observed for classic MAO-A inhibitors. In addition, JL72 behaved as a moderate BuChE inhibitor. Finally, both hydrazines and hydrazides derivatives showed high affinity towards SSAO/VAP-1. Among them, JL72 behaved as a noncompetitive and the most potent inhibitor (IC50 = 0.19 ± 0.04 μM), possessing also a significant anti-inflammatory activity. The combined inhibition of SSAO/VAP-1, MAO (A and B), AChE and BuChE appear as an important therapeutic target to be considered in the treatment of cerebrovascular and neurological disorders such as Alzheimer's disease.

Nitric oxide, derived from nitric oxide synthase (NOS), plays an important role in regulating sympathetic nerve activity. Neuronal NOS (nNOS) is expressed throughout the central and peripheral nervous system. nNOS has a sympathoinhibitory effect under physiological conditions by acting on different sites of the nervous system, including the paraventricular nucleus, the nucleus of the solitary tract, the rostral ventrolateral medulla, the carotid body and nerves in the kidney. nNOS is sympathoinhibitory in a range of diseases including chronic heart failure, chronic renal failure, hypertension and diabetes. nNOS is believed to mediate sympathoinhibitory effects induced by a range of signaling pathways including those promoted by angiotensin-converting enzyme 2 over-expression; statin therapy; angiotensin II type 1 receptor blockers; exercise training; tumor necrosis factor-α blockade; superoxide dismutase mimetics; and estrogen replacement therapy. Increase in nNOS can increase sympathoinhibitory γ-aminobutyric acid activity and decrease sympathoexcitatory angiotensin II signaling and glutamate activity. nNOS may have sympathoexcitatory effects in some circumstances such as chronic heart failure induced by prolonged high salt treatment. The effectiveness of nNOS upregulation in treating sympathetic overactive conditions including chronic heart failure needs to be further investigated.

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) was originally identified in immune cells as playing an important microbicidal role. In stroke and cerebrovascular disease, inflammation is increasingly being recognized as contributing negatively to neurological outcome, with NOX as an important source of superoxide. Several labs have now shown that blocking or deleting NOX in the experimental stroke models protects from brain ischemia. Recent work has implicated glucose as an important NOX substrate leading to reperfusion injury, and that NOX inhibition can improve the detrimental effects of hyperglycemia on stroke. NOX inhibition also appears to ameliorate complications of thrombolytic therapy by reducing blood-brain barrier disruption, edema formation, and hemorrhage. Further, NOX from circulating inflammatory cells seems to contribute more to ischemic injury more than NOX generated from endogenous brain residential cells. Several pharmacological inhibitors of NOX are now available. Thus, blocking NOX activation may prove to be a promising treatment for stroke as well as an adjunctive agent to prevent its secondary complications.

Vascular perturbations and hypoxia are increasingly implicated in Alzheimer's disease (AD) pathogenesis. Cerebral hypoxia induces a large number of inflammatory proteins in brain endothelial cells via signaling pathways that have not been defined. The p38 mitogen-activated protein kinase (MAPK) signaling system has been implicated in endothelial injury and inflammation. The objective of this study is to examine p38 MAPK levels in the cerebromicrovasulature in AD and AD animal models and determine the role of p38 MAPK signaling in hypoxia-mediated effects on brain endothelial cells. Western blot analysis of isolated human brain microvessels show that the phosphorylated (active) form of p38 MAPK (pp38 MAPK) is increased in vessels derived from AD brains compared to control-derived vessels. Similarly, immunofluorescent analysis reveals an increase in cerebrovascular pp38 MAPK as well as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in transgenic AD mice. Exposure of brain endothelial cells to hypoxia (2-6 hours) shows a time-dependent increase in pp38 MAPK. Examination of these cultures at 6 hours hypoxia shows that iNOS and COX-2 are significantly elevated and that the selective p38 MAPK inhibitor SB203580 significantly reduces the hypoxia-mediated increase in their expression. Inhibition of p38 MAPK in cultured brain endothelial cells also significantly decreases the hypoxia-induced increase in the inflammatory proteins, matrix metalloproteinase-2 and angiopoietin-2. These data demonstrate that pp38 MAPK is a key regulator of hypoxia in the cerebrovasculature and suggest that control of this signaling pathway could have therapeutic value in AD and other disorders where hypoxia is involved.

Purpose: Clopidogrel is a prodrug that requires transformation into an active metabolite by cytochrome P450 (CYP) in the liver in order to irreversibly inhibit the P2Y12 adenosine diphosphate platelet receptor. CYP2C19 polymorphism has been reported to correlate with reduced antiplatelet activity of clopidogrel in coronary artery disease. We assessed the association between CYP2C19 polymorphism and clopidogrel resistance in patients with cerebrovascular disease., Materials and Methods: We retrospectively gathered data from patients who experienced cerebrovascular disease, received clopidogrel, and were tested for clopidogrel resistance and CYP2C19 polymorphism. Clopidogrel resistance was tested by the VerifyNow P2Y12 system, and the CYP2C19 polymorphism was tested by the Seeplex CYP2C19 ACE Genotyping system. Clopidogrel resistance was expressed in P2Y12 reaction units (PRU) and percent inhibition. High PRU and low percent inhibition suggests clopidogrel resistance. CYP2C19 polymorphisms were expressed as extensive, intermediate, and poor metabolizers. Clopidogrel resistance was assessed according to the subgroup of CYP2C19 polymorphism., Results: A total of 166 patients were evaluated. The PRU values of extensive CYP2C19 metabolizers (195.0±84.9) were significantly lower than those of intermediate and poor metabolizers (237.9±88.0, 302.2±58.9). The percent inhibition of extensive metabolizers (44.6±21.8) was significantly higher than that of intermediate and poor metabolizers (30.5±21.5, 14.0±13.4)., Conclusion: Intermediate and poor metabolizing CYP2C19 polymorphism is associated with reduced clopidogrel antiplatelet activity in patients with cerebrovascular disease. The clinical implications of this finding require further investigation.

Cerebral small-vessel disease is a common disorder in elderly populations; however, its molecular basis is not well understood. We recently demonstrated that mutations in the high-temperature requirement A (HTRA) serine peptidase 1 (HTRA1) gene cause a hereditary cerebral small-vessel disease, cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL). HTRA1 belongs to the HTRA protein family, whose members have dual activities as chaperones and serine proteases and also repress transforming growth factor-β (TGF-β) family signaling. We demonstrated that CARASIL-associated mutant HTRA1s decrease protease activity and fail to decrease TGF-β family signaling. However, the precise molecular mechanism for decreasing the signaling remains unknown. Here we show that increased expression of ED-A fibronectin is limited to cerebral small arteries and is not observed in coronary, renal arterial or aortic walls in patients with CARASIL. Using a cell-mixing assay, we found that HTRA1 decreases TGF-β1 signaling triggered by proTGF-β1 in the intracellular space. HTRA1 binds and cleaves the pro-domain of proTGF-β1 in the endoplasmic reticulum (ER), and cleaved proTGF-β1 is degraded by ER-associated degradation. Consequently, the amount of mature TGF-β1 is reduced. These results establish a novel mechanism for regulating the amount of TGF-β1, specifically, the intracellular cleavage of proTGF-β1 in the ER.

Modern view on pathogenesis and clinics of one of the most important forms of chronic cerebrovascular insufficiency--discirculatory encephalopathy has been presented in this article. The author has analyzed requirements to optimal treatment choice of this pathology. Action mechanisms and peculiarities of clinical use of Vasonat medication were detailed. This medication with good clinical and pharmacological properties allows to realize the strategy of pathogenetically proved neuromethabolical pharmacotherapy in angioneurology. Clinical advantage of Vasonat, its safety characteristics, and recommendations of practical use have been detailed.

Background and Purpose: Data on the prevalence of Fabry disease in patients with central nervous system pathology are limited and controversial. In this study, we assessed the prevalence of Fabry disease in young patients presenting with cerebrovascular disease in Belgium., Methods: In this national, prospective, multicenter study, we screened for Fabry disease in 1000 patients presenting with ischemic stroke, transient ischemic attack, or intracranial hemorrhage; unexplained white matter lesions; or vertebrobasilar dolichoectasia. In male patients, we measured alpha-galactosidase A (alpha-GAL A) activity in dried blood spots. Female patients were screened for mutations by exonic DNA sequencing of the alpha-GAL A gene., Results: alpha-GAL A activity was deficient in 19 men (3.5%), although all had normal alpha-GAL A gene sequences. Enzymatic deficiency was confirmed on repeat assessment in 2 male patients (0.4%). We identified missense mutations in 8 unrelated female patients (1.8%): Asp313Tyr (n=5), Ala143Thr (n=2), and Ser126Gly (n=1). The pathogenicity of the 2 former missense mutations is controversial. Ser126Gly is a novel mutation that can be linked to late-onset Fabry disease., Conclusions: alpha-GAL A deficiency may play a role in up to 1% of young patients presenting with cerebrovascular disease. These findings suggest that atypical variants of Fabry disease with late-onset cerebrovascular disease exist, although the clinical relevance is unclear in all cases.

Background and Purpose: Matrix metalloproteinases (MMP) may play a role in blood-brain barrier (BBB) disruption after ischemic stroke. We hypothesized that plasma concentrations of MMP-9 are associated with a marker of BBB disruption in patients evaluated for acute stroke., Methods: Patients underwent MRI on presentation and approximately 24 hours later. The MRI marker, termed hyperintense acute reperfusion injury marker (HARM), is gadolinium enhancement of cerebrospinal fluid on fluid-attenuated inversion recovery MRI. Plasma MMP-9 and tissue inhibitor of matrix metalloproteinase-1 were measured by enzyme-linked immunosorbent assay. Logistic regression models tested for predictors of HARM on 24-hour follow-up scans separately for MMP-9 and the ratio of MMP-9 to TIMP-1., Results: For the 41 patients enrolled, diagnoses were: acute ischemic cerebrovascular syndrome, 33 (80.6%); intracerebral hemorrhage, 6 (14.6%); stroke mimic, 1 (2.4%); and no stroke, 1 (2.4%). HARM was present in 17 (41.5%) patients. In model 1, HARM was associated with baseline plasma MMP-9 concentration (odds ratio [OR], 1.01; 95% confidence interval [CI], 1.001-1.019; P=0.033). In model 2, HARM was associated with the ratio of MMP-9 to tissue inhibitor of matrix metalloproteinase-1 (OR, 4.94; 95% CI, 1.27-19.14; P=0.021)., Conclusions: Baseline MMP-9 was a significant predictor of HARM at 24-hour follow-up, supporting the hypothesis that MMP-9 is associated with BBB disruption. If the association between MMP-9 and BBB disruption is confirmed in future studies, HARM may be a useful imaging marker to evaluate MMP-9 inhibition in ischemic stroke and other populations with BBB disruption.

Objective: Relevant soluble matrix metalloproteinases (MMPs), their inhibitors, tissue inhibitor of metalloproteinases (TIMPs), and serological factors were analyzed as possible biomarkers for neurological symptoms in patients with carotid artery stenosis., Methods and Results: Asymptomatic (n = 76) and symptomatic (n = 69) patients were evaluated. Serum levels of collagenases (MMP-1, -8), gelatinases (MMP-2, -9), stromelysin (MMP-3), matrilysin (MMP-7), and TIMP-1, -2 were determined by enzyme-linked immunosorbant assay (ELISA). Furthermore, fibrinogen, C-reactive protein (CRP), leukocytes, and further serological parameters were measured. Circulating MMP-7, -8, -9, and TIMP-1 were significantly enhanced in symptomatic individuals with P < .001 for MMP-7 and P < .05 for MMP-8, -9, and TIMP-1. Significant correlations were found between various MMPs with highest correlation coefficient of r = .749 between MMP-8 and -9. In addition, MMP-1, -3, -7, -9 correlated significantly with leukocytes, MMP-1, and TIMP-1 with thrombocytes, MMP-8 with fibrinogen, and MMP-7 with creatinine. Combination of more than one biomarker led to significantly enhanced positive predictive value (PPV) for neurological symptom compared to single MMP (MMP-7 + MMP-9: PPV = 73.1%, MMP-7 + MMP-8 + MMP-9: PPV = 73.8% vs. PPV = 62.5%; P < .001)., Conclusions: Thus, using appropriate analytical approaches, we showed for the first time the possibility to use set of relevant biomarkers as predictors of neurological symptoms. Such biomarkers together with current diagnostic techniques may further contribute to recognize vulnerable lesions to define patients at risk.

Alzheimer disease (AD) and stroke are two leading causes of age-associated dementia. Increasing evidence points to vascular damage as an early contributor to the development of AD and AD-like pathology. In this review, we discuss the role of G protein-coupled receptor kinase 2 (GRK2) as it relates to individuals affected by AD and how the cardiovasculature plays a role in AD pathogenesis. The possible involvement of GRKs in AD pathogenesis is an interesting notion, which may help bridge the gap in our understanding of the heartbrain connection in relation to neurovisceral damage and vascular complications in AD, since kinases of this family are known to regulate numerous receptor functions both in the brain, myocardium, and elsewhere. The aim of this review is to discuss our findings of overexpression of GRK2 in the context of the early pathogenesis of AD, because increased levels of GRK2 immunoreactivity were found in vulnerable neurons of AD patients as well as in a two-vessel occlusion (2-VO) mammalian model of ischaemia. Also, we consider the consequences for this overexpression as a loss of G-protein coupled receptor (GPCR) regulation, as well as suggest a potential role for GPCRs and GRKs in a unifying theory of AD pathogenesis, particularly in the context of cerebrovascular disease. We synthesize this newer information and attempt to put it into context with GRKs as regulators of diverse physiological cellular functions that could be appropriate targets for future pharmacological intervention.

Subnormal leukocyte α-galactosidase (α-Gal) activity was found during evaluation of an adolescent male with cryptogenic cerebrovascular small-vessel disease. The only molecular abnormality found was the g.1170C>T single-nucleotide polymorphism (SNP) in the 5' untranslated region of exon 1 in the α-Gal gene (GLA). Historically, this polymorphism has been considered to be biologically neutral. To test the hypothesis that the g.1170T allele might be associated with lower α-Gal expression, we genotyped GLA exon 1 and measured leukocyte and plasma α-Gal in the parents, brother and sister of the index case. The g.1170T allele co-segregated with a subnormal leukocyte α-Gal activity in the three siblings. Although plasma enzyme activities were within the normal range in all five relatives, the ranking of their values suggested a dosage effect of the g.1170T allele. Western blotting assays of leukocyte protein extracts showed that the relative expression of α-Gal in both the patient and his sister was significantly lower than in sex-matched hemizygous or homozygous controls for the g.1170C allele, either normalized to the β-actin immunoblot expression or standardized to a known amount of recombinant human α-Gal. These family data, in combination with results from a recent GLA SNP screening study among healthy Portuguese individuals, suggest that the g.1170C>T SNP may be co-dominantly associated with a relatively decreased GLA expression at the transcription and/or translation level. Larger population studies are needed to confirm these findings and to test the hypothesis that the GLA g.1170C>T may contribute to the multifactorial risk of ischaemic small-vessel cerebrovascular disease.

A 24-year-old female with an anomalous systemic arterial (ASA) supply to normal basal segments of the left lower lobe (LLL) has been suffering from occasional hemoptysis for the last 4.5 years. Our hospital has been following her up for the last 2.5 years. In the first chest radiograph, an unobvious retrocardiac hazy nodule was shown. The following chest computed tomography scan performed indicated clearly this anomaly. According to our analysis of similar reported cases in the English medical literature, the statistics suggest a close relation between Asian population and this anomaly. Therefore, ASA supply to normal basal segments of the LLL should be put into consideration when examining an Asian patient with symptoms of hemoptysis or exertional dyspnea but showing no obvious image findings in chest radiographs.

The study of reactive oxygen species (ROS) and oxidative stress remains a very active area of biological research, particularly in relation to cellular signaling and the role of ROS in disease. In the cerebral circulation, oxidative stress occurs in diverse forms of disease and with aging. Within the vessel wall, ROS produce complex structural and functional changes that have broad implications for regulation of cerebral perfusion and permeability of the blood-brain barrier. These oxidative-stress-induced changes are thought to contribute to the progression of cerebrovascular disease. Here, we highlight recent findings in relation to oxidative stress in the cerebral vasculature, with an emphasis on the emerging role for NADPH oxidases as a source of ROS and the role of ROS in models of disease.

Objective: The risk of cerebrovascular events in patients with mild to moderate peripheral vascular disease is significant. Cilostazol is a phosphodiesterase type 3 (PDE3) inhibitor that is effective in the treatment of symptoms of peripheral arterial occlusive disease. The method of action includes antithrombotic, vasodilatory, and antiproliferative effects., Methods: The Cilostazol: A Study in Long-Term Effects (CASTLE) trial was a prospective randomized double-blinded trial to establish the safety of this PDE3 inhibitor use in 1435 patients with mild to moderate peripheral arterial occlusive disease. A post hoc analysis of the CASTLE trial was undertaken to evaluate cilostazol use on cerebrovascular events. Blinded adjudication of all cerebrovascular events (stroke, transient ischemic attack, and carotid revascularization) in this trial was performed. Kaplan-Meier analysis was used for statistical evaluation., Results: The overall rate of cerebrovascular events was 4.6% (67 of 1435 patients) with a mean follow-up of 515 days. Ischemic vascular events were more common (2.5%) than hemorrhagic events (0.3%; P < .05). The placebo group demonstrated a greater risk for events (6.1%; 43 of 718 patients) versus the cilostazol treated group (3.2%; 24 of 717 patients; P < .05). Cerebrovascular risk factors were similar in both groups., Conclusion: The risk of cerebrovascular events in patients with mild to moderate peripheral arterial occlusive disease is 4.6% with a mean follow-up of 515 days. Treatment with PDE3 inhibitors may reduce this risk. Further evaluation of the use of PDE3 inhibitors for prevention of cerebrovascular events should be considered.

Background: Macrophage infiltration and expression of matrix metalloproteinase-9 (MMP-9) are markers of high-risk atherosclerotic carotid plaques and strong indicators of plaque instability. Use of statins is associated with a decreased risk of stroke and reportedly improves stability of atherosclerotic plaques, but available data addressing the mechanism of this effect are conflicting., Methods: We retrospectively analyzed data from 94 consecutive patients with internal carotid artery stenosis who underwent carotid endarterectomy. Excised plaques underwent systematic quantitative immunohistochemical analysis to determine the percentage of macrophage area and the percentage of MMP-9 area. Associations between percentage of macrophage area and percentage of MMP-9 area and use of statins and cerebrovascular disease were examined by univariate and multivariate analysis., Results: We found significantly higher values of percentage of macrophage area and of MMP-9 area in recently symptomatic (n = 26) compared with asymptomatic (n = 68) internal carotid artery stenoses: median (IQR) percentage of macrophage area was 2.29 (1.53-4.129) vs 0.53 (0.27-0.96) and percentage of MMP-9 area was 0.61 (0.36-0.89) vs 0.08 (0.02-0.27; both P < .0005). Patients treated with statins (n = 49) showed lower percentage values of macrophage area and MMP-9 area than untreated patients: the percentage of macrophage area was 0.54 (0.31-1.18) vs 1.03 (0.57-2.08; P = .01) and percentage of MMP-9 area was 0.06 (0.02-0.22) vs 0.36 (0.16-0.62; P < .0005). These associations between statin treatment and percentages of macrophage area and MMP-9 area did not change after controlling for symptomatic cerebrovascular disease and the effects of other potential confounders in multivariable analysis., Conclusions: Our results confirm the value of percentage of macrophage area and percentage of MMP-9 area as markers of plaque instability and provide further evidence to support the hypothesis that statins reduce inflammatory responses and thereby stabilize carotid atherosclerotic plaques.

The constitutive isoform of heme oxygenase, HO-2, is highly expressed in the brain and in cerebral vessels. HO-2 functions in the brain have been evaluated using pharmacological inhibitors of the enzyme and HO-2 gene deletion in in vivo animal models and in cultured cells (neurons, astrocytes, cerebral vascular endothelial cells). Rapid activation of HO-2 via post-translational modifications without upregulation of HO-2 expression or HO-1 induction coincides with the increase in cerebral blood flow aimed at maintaining brain homeostasis and neuronal survival during seizures, hypoxia, and hypotension. Pharmacological inhibition or gene deletion of brain HO-2 exacerbates oxidative stress induced by seizures, glutamate, and inflammatory cytokines, and causes cerebral vascular injury. Carbon monoxide (CO) and bilirubin, the end products of HO-catalyzed heme degradation, have distinct cytoprotective functions. CO, by binding to a heme prosthetic group, regulates the key components of cell signaling, including BK(Ca) channels, guanylyl cyclase, NADPH oxidase, and the mitochondria respiratory chain. Cerebral vasodilator effects of CO are mediated via activation of BK(Ca) channels and guanylyl cyclase. CO, by inhibiting the major components of endogenous oxidant-generating machinery, NADPH oxidase and the cytochrome C oxidase of the mitochondrial respiratory chain, blocks formation of reactive oxygen species. Bilirubin, via redox cycling with biliverdin, is a potent oxidant scavenger that removes preformed oxidants. Overall, HO-2 has dual housekeeping cerebroprotective functions by maintaining autoregulation of cerebral blood flow aimed at improving neuronal survival in a changing environment, and by providing an effective defense mechanism that blocks oxidant formation and prevents cell death caused by oxidative stress.

Purpose: To assess baseline and follow-up plasma concentrations of metalloproteinase-9 (MMP-9), MMP-2, and tissue inhibitor of metalloproteinase-2 (TIMP-2) in patients undergoing carotid thromboendarterectomy (TEA) in relation to tissue expression and diagnostic features., Basic Methods: Using sandwich enzyme-linked immunosorbent assay, plasma levels of enzymes were determined in 15 patients undergoing carotid TEA. Tissue sections were incubated with specific antibodies and fluorescence intensity was analyzed., Principal Findings: MMP-9 levels were higher in patients with carotid stenosis versus controls, significantly in those with cerebral lesions at neuroimaging. MMP-9 levels decreased in 93.4% of the patients at 1 month. MMP-2 levels tended to increase 30 days after surgery. TIMP-2 showed no difference., Conclusions: High concentrations of MMP-9 found in patients with carotid stenosis and cerebral lesions suggest that MMP-9 assay could be useful in the evaluation of all carotid lesions to help identify those at highest risk of a neurologic event.

In dyscirculatory encephalopathy and moderate ischemic stroke there are single changes of components of glutathione metabolism. In moderate and severe ischemic stroke frequent and considerable changes have been revealed. Changes in hemorrhagic stroke are also expressed. An increase of activities of glutathione peroxidase and glutathione transferase is the most typical, rarely the increase of glutathione reductase and GSH is observed. The increase of enzymes activity was absent at the delayed oneset of treatment (more than 3 days) and in severe cases patients who died later. Glutathione system is important in the tolerance to cerebral ischemia.

The present study was performed to assess the prophylactic effect of 7-nitroindazole (7-NI), an inhibitor of neuronal nitric oxide synthase (nNOS), in an animal model of heatstroke. Anesthetized rats, immediately before the start of heat stress, were divided into two major groups and given the following: vehicle solution (1 mL per kg body weight) or 7-NI (5-20mg/mL per kg body weight) intraperitoneally. They were exposed to ambient temperature of 43 degrees C to induce heatstroke. Another group of rats were exposed to room temperature (24 degrees C) and used as normothermic controls. Their physiologic and biochemical parameters were continuously monitored. When the vehicle-pretreated rats underwent heat stress, their survival time values were found to be 21-25 min. Pretreatment with intraperitoneal doses of 7-NI significantly improved survival during heatstroke (55-164 min). As compared to those of normothermic controls, all vehicle-pretreated heatstroke animals displayed higher levels of core temperature, intracranial pressure, nitric oxide metabolite (NO(2)(-)), glutamate, glycerol, lactate/pyruvate ratio, neuronal damage score and nNOS expression in the hypothalamus, and tumor necrosis factor-alpha (TNF-alpha) in the serum. In contrast, all vehicle-pretreated heatstroke animals had lower levels of mean arterial pressure, cerebral perfusion pressure, cerebral blood flow, and brain PO(2). Administration of 7-NI before the start of heat exposure significantly reduced the hyperthermia, intracranial hypertension, nNOS-dependent NO(2)(-), glutamate, glycerol, lactate/pyruvate ratio, and neuronal damage score in the hypothalamus, as well as overproduction of TNF-alpha in the serum that occurred during heatstroke. The data show that reduction of nNOS-dependent NO(2)(-) with 7-NI causes attenuation of cerebrovascular dysfunction, hyperthermia, and TNF-alpha overproduction during heatstroke in the rat.

Background and Purpose: The small G protein rhoA and its downstream effector rho-kinase are both expressed in vascular cells and are involved in several cellular processes. One of these processes is the regulation of the phosphorylation state of myosin light chain in vascular muscle and thus, the development of force. Recently, considerable evidence for increased activity of this pathway in cerebral and noncerebral vessels has been reported in several cardiovascular diseases associated with increased vascular tone., Summary of Review: The main aim of this brief review is to summarize current evidence for the involvement of rhoA/rho-kinase signaling in dysfunction of the cerebral circulation in disease states, such as cerebral vasospasm, hypertension, diabetes, and ischemic brain injury. We will also briefly consider the novel hypothesis that augmented activity of endothelial rho-kinase decreases nitric oxide production and contributes to increased vascular tone in disease and the possibility of this action being a key therapeutic target of statins (inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase) in cerebral and noncerebral arteries., Conclusions: Considerable evidence indicates that rhoA/rho-kinase activity is commonly increased in cerebral vascular disease, not only in vascular muscle, but also in the endothelium and possibly in inflammatory cells and neurons.

Background: Methionine synthase (MS) catalyzes the folate-dependent remethylation of homocysteine to methionine. We tested the hypothesis that deficiency of MS impairs endothelial function in mice heterozygous for disruption of the Mtr gene, which encodes MS., Methods and Results: Plasma total homocysteine was similar in wild-type (Mtr(+/+)) and heterozygous (Mtr(+/-)) mice fed a control diet (4.5+/-0.3 and 5.3+/-0.4 micromol/L, respectively) and mildly elevated in Mtr(+/+) and Mtr(+/-) mice fed a low-folate (LF) diet (7.5+/-0.7 and 9.6+/-1.2 micromol/L, respectively; P<0.001 versus control diet). Dilatation of cerebral arterioles to the endothelium-dependent dilator, acetylcholine (10 micromol/L) was blunted in Mtr(+/-) mice compared with Mtr(+/+) mice fed the control diet (21+/-4 versus 32+/-4%; P<0.05). Both Mtr(+/+) and Mtr(+/-) mice exhibited impaired dilatation of cerebral arterioles to acetylcholine when they were fed the LF diet (12+/-2 and 14+/-2%, respectively; P<0.01 versus Mtr(+/+) mice fed the control diet). Elevated levels of superoxide and hydrogen peroxide were detected by confocal microscopy in cerebral arterioles of Mtr(+/-) mice fed the control diet and in both Mtr(+/+) and Mtr(+/-) mice fed the LF diet., Conclusions: These findings demonstrate that defective homocysteine remethylation caused by deficiency of either MS or folate produces oxidative stress and endothelial dysfunction in the cerebral microcirculation of mice.

Despite biological support for a role of angiotensin converting enzyme (ACE) in Alzheimer's disease (AD), studies assessing the ACE I/D polymorphism in AD are conflicting. We re-evaluated this association in the Rotterdam Study, a population-based cohort study. The mechanism of association was further explored by adjusting for vascular factors, and by analysing atrophy, white matter lesions and infarcts on MRI in non-demented individuals. Genotypes were available for 6488 participants. During average follow-up of 6 years 250 subjects developed AD. MRI data were available for 494 non-demented participants. Homozygosity for the I-allele conferred a slightly increased risk of AD compared to carrying a D-allele (RR 1.12 (95% CI 0.99-1.25)). This increase was only significant in women, and independent of vascular factors (RR 1.39 (95% CI 1.14-1.69)). Non-demented women with the II genotype had smaller hippocampal and amygdalar volumes. Vascular pathology was not significantly associated with ACE. This suggests a modest but significant increase in risk of AD and early AD pathology in women homozygous for the ACE I-allele independent of vascular factors.

Matrix metalloproteinases are important factors for tissue remodelling and are activated during several physiological and pathological conditions, including cerebrovascular diseases. We give an overview of the structure, production and physiological effects of these widely distributed proteases and describe the genetic background and regulation pathways. In particular, we discuss the role of matrix metalloproteinases in vascular remodelling concerning ischaemic stroke, brain haemorrhage, vascular dementia, carotid artery plaques and cerebral aneurysms., (Copyright (c) 2005 S. Karger AG, Basel.)

Huperzine A (HupA), isolated from Chinese herb Huperzia serrata, is a potent, highly specific and reversible inhibitor of acetylcholinesterase. It has been found to reverse or attenuate cognitive deficits in a broad range of animal models. Clinical trials in China have demonstrated that HupA significantly relieves memory deficits in aged subjects, patients with benign senescent forgetfulness, Alzheimer's disease (AD) and vascular dementia (VD), with minimal peripheral cholinergic side effects compared with other AChEIs in use. HupA possesses the ability to protect cells against hydrogen peroxide, beta-amyloid protein (or peptide), glutamate, ischemia and staurosporine-induced cytotoxicity and apoptosis. These protective effects are related to its ability to attenuate oxidative stress, regulate the expression of apoptotic proteins Bcl-2, Bax, P53 and caspase-3, protect mitochondria, and interfere with APP metabolism. Antagonizing effects on NMDA receptors and potassium currents may contribute to the neuroprotection as well. It is also possible that the non-catalytic function of AChE is involved in neuroprotective effects of HupA. The therapeutic effects of HupA on AD or VD are probably exerted via a multi-target mechanism., (2005 S. Karger AG, Basel)

Matrix metalloproteinases (MMP) are a family of proteases involved in the remodelling of the extracellular matrix. In physiological conditions, the activity of MMP is regulated on several levels: gene transcription, activation of inactive precursors, and inhibition by endogenous factors. Loss of control and increased expression and activity of MMP have been implicated in various diseases (cancer, arthritis, vascular aneurysms, atherosclerosis, etc.). In the central nervous system, MMP are involved in the mechanisms associated with neuroinflammation, which is different in vascular and non-vascular diseases. MMP, especially MMP-9, have been shown to induce a high breakdown capacity, especially in the arteriolar basement membrane, leading to cerebral edema and secondary hemorrhage. In human clinical aspects, MMP are associated to intracerebral hemorrhage growth and with the development of complications in ischemic stroke. Combination therapies explicitly involving MMP inhibition could be of value in future treatment strategies.

Nitric oxide (NO) is an enzymatic product of nitric oxide synthase (NOS). NO has significant physiological functions and an increasing body of evidence suggests that NO pathways are implicated in a number of neurological disorders, including Alzheimer's disease (AD) and other neurodegenerative dementias. NO is continuously released by endothelial cells in the vascular system, whereas advanced age in the presence of vascular risk factor causes a decrease in cerebral blood flow, involving microvasculopathy with impaired NO release, which in turn results in regional metabolic dysfunction. This finding suggests that vascular pathology plays a crucial role in the pathogenesis of so-called neurodegenerative dementias. Inflammatory responses are commonly found in the brain under a variety of neurodegenerative dementias, including AD and dementia with Lewy bodies, in which up-regulation of NOS expression, suggesting overproduction of NO, is found in neurons and glia. NO is thought to be involved in such neuroinflammation due to its free radical properties, which compromise cellular integrity and viability via mitochondrial damage. Further studies to elucidate NO pathways in neurodegenerative dementias could lead to a better understanding of their pathogenesis and improved therapeutic strategies, and therefore are certainly warranted.

Nitric oxide (NO) is a short-life key bioregulatory active molecule in the cardiovascular, immune and nervous systems. NO is synthesized by converting L-arginine to L-citrulline by enzymes called NO synthase (NOS). The growing body of evidence strongly supports the theory that this molecule appears to be one of the key targets for the disruption of normal brain homeostasis, which causes the development of brain lesions and pathology such as in Alzheimer's disease (AD) or other related dementia. The vascular content of NO activity appears especially to be a main contributor to this pathology before the over-expression of other NOS isoforms activity in a different brain cellular compartment. We speculate that pharmacological intervention using NO donors and/or NO suppressors will be able to delay or minimize the development of brain pathology and further progression of mental retardation.

Obstructive sleep apnea, apnea of prematurity, and sudden infant death syndrome are associated with a high risk of morbidity and mortality secondary to the neuronal and cerebrovascular consequences of the associated intermittent hypoxia. We hypothesized that episodic hypoxia (EH) promotes inflammation in the cerebral microcirculation and that nitric oxide (NO) produced by the endothelial and neuronal isoforms of NO synthase (eNOS and nNOS, respectively) modulates this response. Anesthetized and ventilated Swiss-Webster ND4 mice, wild-type mice, and NO synthase knockout mice were subjected to a 1-h period of EH (twelve 30-s periods of hypoxia every 5 min). Four, 24, or 48 h later, mice were reanesthetized for imaging of leukocyte dynamics in the cortical venular microcirculation by epifluorescence videomicroscopy through closed cranial windows. In Swiss-Webster ND4 mice, leukocyte adherence increased 2.1-fold at 4 h, 3.4-fold at 24 h, and 1.8-fold at 48 h relative to time-matched, normoxic controls; there was no evidence of delayed hippocampal CA1 pyramidal cell death. A similar response was noted in wild-type mice. However, in eNOS knockouts, leukocyte-endothelial cell adherence was elevated to 4.4-fold over baseline 24 h after EH, and a significant fraction of these animals showed evidence of delayed CA1 cell death. Conversely, in nNOS knockouts, no increase in adherence was noted at 24 h and CA1 viability remained unaffected. We conclude that NO derived from nNOS promotes an inflammatory response in the cerebrovascular microcirculation after short-term EH and that NO produced by eNOS blunts the extent of this response and exerts neuroprotective effects.

Antithrombotic activity of catalase (CAT) and chondroitin sulfate (CHS) preparations was studied in a rat model of arterial injury induced by ferrous chloride. Equal doses (according to catalytically active CAT) were used to examine the effect of native CAT, CAT-CHS covalent conjugate and mixture of native CAT and free CHS in a ratio corresponding to their contents in the conjugate. The antithrombotic activity of the derivatives was determined by the time during which arterial occlusion developed (occlusion time) and by the mass of the formed thrombus. The antithrombotic activities of the conjugate and mixture were similar and markedly higher than that of native CAT. The conjugate was more effective with respect to deceleration and prevention of arterial occlusion. Small doses of the preparations altered the structure of the formed thrombus, promoting sustained blood flow. Further investigations of the antithrombotic activity of CAT, superoxide dismutase and CHS derivatives have been outlined.