Prevention of stroke in patients with hypertension

Prognostic identifier of cerebrovascular complications in tuberculous meningitis: Meta-analysis

INTRODUCTION

Cerebrovascular complications could occur in 15-57 % of patients with tuberculous meningitis (TBM). It is crucial to rapidly identify TBM patients who are at risk for stroke. This study aimed to find predictors of stroke in patients with TBM.

METHODS

This systematic review and meta-analysis were done using literature searches through online databases up to April 30th, 2022. Three independent authors performed literature screening, data extraction, and critical appraisal of the studies. Eight studies involving 1535 samples were included.

RESULTS

We analyzed data regarding demographic, comorbidity, clinical presentation, radiologic, and laboratory parameters. Overall, clinical presentation that showed outcome difference was found in patients with findings of vomiting (OR = 2.71, 95 % CI: 1.30-5.63), cranial nerve deficit (OR = 4.10, 95 % CI: 1.83-9.21), focal deficit (OR = 5.56, 95 % CI: 2.24-13.79), and altered consciousness (OR = 1.90, 95 % CI: 1.24-2.92). Some comorbidities showed significant differences such as diabetes mellitus (OR = 2.58, 95 % CI: 1.51-4.41), hypertension (OR = 5.73, 95 % CI: 3.36-9.77), ischemic heart disease (OR = 2.18, 95 % CI: 1.02-4.63), and smoking (OR = 2.65, 95 % CI: 1.22-5.77). Two radiological changes shown to have significantly higher proportions are hydrocephalus (OR = 2.50, 95 % CI: 1.74-3.58) and meningeal enhancements (OR = 3.99, 95 % CI: 1.73-9.20).

CONCLUSION

Our analysis indicated that clinical presentations of vomiting, cranial nerve deficit, focal deficit, altered consciousness; comorbidity of diabetes mellitus, hypertension, smoking history, ischemic heart disease; and radiological findings of meningeal enhancement and hydrocephalus showed significant association with stroke incidence in tuberculous meningitis.

Mechanisms linking obesity and its metabolic comorbidities with cerebral grey and white matter changes

Obesity is a preventable risk factor for cerebrovascular disorders and it is associated with cerebral grey and white matter changes. Specifically, individuals with obesity show diminished grey matter volume and thickness, which seems to be more prominent among fronto-temporal regions in the brain. At the same time, obesity is associated with lower microstructural white matter integrity, and it has been found to precede increases in white matter hyperintensity load. To date, however, it is unclear whether these findings can be attributed solely to obesity or whether they are a consequence of cardiometabolic complications that often co-exist with obesity, such as low-grade systemic inflammation, hypertension, insulin resistance, or dyslipidemia. In this narrative review we aim to provide a comprehensive overview of the potential impact of obesity and a number of its cardiometabolic consequences on brain integrity, both separately and in synergy with each other. We also identify current gaps in knowledge and outline recommendations for future research.

Changes in the choroid plexuses and brain barriers associated with high blood pressure and ageing

INTRODUCTION

The choroid plexuses, blood vessels, and brain barriers are closely related both in terms of morphology and function. Hypertension causes changes in cerebral blood flow and in small vessels and capillaries of the brain. This review studies the effects of high blood pressure (HBP) on the choroid plexuses and brain barriers.

DEVELOPMENT

The choroid plexuses (ChP) are structures located in the cerebral ventricles, and are highly conserved both phylogenetically and ontogenetically. The ChPs develop during embryogenesis, forming a functional barrier during the first weeks of gestation. They are composed of highly vascularised epithelial tissue covered by microvilli, and their main function is cerebrospinal fluid (CSF) production. The central nervous system (CNS) is protected by the blood-brain barrier (BBB) and the blood-CSF barrier (BCSFB). While the BBB is formed by endothelial cells of the microvasculature of the CNS, the BCSFB is formed by epithelial cells of the choroid plexuses. Chronic hypertension induces vascular remodelling. This prevents hyperperfusion at HBPs, but increases the risk of ischaemia at low blood pressures. In normotensive individuals, in contrast, cerebral circulation is self-regulated, blood flow remains constant, and the integrity of the BBB is preserved.

CONCLUSIONS

HBP induces changes in the choroid plexuses that affect the stroma, blood vessels, and CSF production. HBP also exacerbates age-related ChP dysfunction and causes alterations in the brain barriers, which are more marked in the BCSFB than in the BBB. Brain barrier damage may be determined by quantifying blood S-100β and TTRm levels.

Pathogenetic Mechanisms of Hypertension-Brain-Induced Complications: Focus on Molecular Mediators

There is growing evidence that hypertension is the most important vascular risk factor for the development and progression of cardiovascular and cerebrovascular diseases. The brain is an early target of hypertension-induced organ damage and may manifest as stroke, subclinical cerebrovascular abnormalities and cognitive decline. The pathophysiological mechanisms of these harmful effects remain to be completely clarified. Hypertension is well known to alter the structure and function of cerebral blood vessels not only through its haemodynamics effects but also for its relationships with endothelial dysfunction, oxidative stress and inflammation. In the last several years, new possible mechanisms have been suggested to recognize the molecular basis of these pathological events. Accordingly, this review summarizes the factors involved in hypertension-induced brain complications, such as haemodynamic factors, endothelial dysfunction and oxidative stress, inflammation and intervention of innate immune system, with particular regard to the role of Toll-like receptors that have to be considered dominant components of the innate immune system. The complete definition of their prognostic role in the development and progression of hypertensive brain damage will be of great help in the identification of new markers of vascular damage and the implementation of innovative targeted therapeutic strategies.

Post-traumatic stress disorder and its association with stroke and stroke risk factors: A literature review

Stroke is a major cause of mortality and disability globally that has multiple risk factors. A risk factor that has recently gained more attention is post-traumatic stress disorder (PTSD). Literature searches were carried out for updated PTSD information and for the relationship between PTSD and stroke. The review was divided into two sections, one exploring PTSD as an independent risk factor for stroke, with a second concentrating on PTSD's influence on stroke risk factors. The study presents accumulating evidence that shows traumatic stress predicts stroke and is also linked to many major stroke risk factors. The review contributes knowledge to stroke aetiology and acts as a reference for understanding the relationship between PTSD and stroke. The information presented indicates that screening and identification of traumatic experience would be beneficial for directing stroke patients to appropriate psychological and lifestyle interventions. In doing so, the burden of stroke may be reduced worldwide.

Neurological complications of systemic hypertension

Systemic hypertension is the most common, most easily diagnosed, and one of the most reversible risk factors for neurologic pathology. Acute severe hypertension above a mean arterial pressure of approximately 150mmHg exceeds the brain's autoregulatory capacity and results in increased cerebral blood flow leading to hypertensive encephalopathy. Chronic hypertension predisposes to cerebral vasculature atherosclerosis, medial hypertrophy, luminal narrowing, endothelial dysfunction, impaired arterial relaxation, and decreased ability to augment cerebral blood flow at low blood pressures. The pathologic effects of hypertension increase stroke risk by three- to fivefold. With three-fourths of strokes incident events, primary prevention is essential. Multiple studies have demonstrated the benefit of blood pressure lowering in reducing incident and recurrent strokes. Even more, hypertension is a risk factor for cognitive impairment and dementia through multifactorial mechanisms including vascular compromise, cerebral small vessel disease, white matter disease (leukoaraiosis), cerebral microbleeds, cerebral atrophy, amyloid plaque deposition, and neurofibrillary tangles. In patients without hypotension, treatment with antihypertensives slows progression and assuages the degree of cognitive decline. While the choice of antihypertensive did not make a significant difference in most cognitive outcome studies, some large meta-analyses have pointed to angiotensin receptor blockers as the favored agent. Because of the well-documented morbidity and mortality associated with unchecked hypertension, treating and preventing hypertension are universally critical pillars in healthcare.

MRI study of cerebral blood flow, vascular reactivity, and vascular coupling in systemic hypertension

Chronic hypertension alters cerebrovascular function, which can lead to neurovascular pathologies and increased susceptibility to neurological disorders. The purpose of this study was to utilize in vivo MRI methods with corroborating immunohistology to evaluate neurovascular dysfunction due to progressive chronic hypertension. The spontaneously hypertensive rat (SHR) model at different stages of hypertension was studied to evaluate: i) basal cerebral blood flow (CBF), ii) cerebrovascular reactivity (CVR) assessed by CBF and blood-oxygenation level dependent (BOLD) signal changes to hypercapnia, iii) neurovascular coupling from CBF and BOLD changes to forepaw stimulation, and iv) damage of neurovascular unit (NVU) components (microvascular, astrocyte and neuron densities). Comparisons were made with age-matched normotensive Wistar Kyoto (WKY) rats. In 10-week SHR (mild hypertension), basal CBF was higher (p < 0.05), CVR trended higher, and neurovascular coupling response was higher (p < 0.05), compared to normotensive rats. In 40-week SHR (severe hypertension), basal CBF, CVR, and neurovascular coupling response were reversed to similar or below normotensive rats, and were significantly different from 10-week SHR (p < 0.05). Immunohistological analysis found significantly reduced microvascular density, increased astrocytes, and reduced neuronal density in SHR at 40 weeks (p < 0.05) but not at 10 weeks (p > 0.05) in comparison to age-matched controls. In conclusion, we observed a bi-phasic basal CBF, CVR and neurovascular coupling response from early to late hypertension using in vivo MRI, with significant changes prior to changes in the NVU components from histology. MRI provides clinically relevant data that might be useful to characterize neurovascular pathogenesis on the brain in hypertension.

Association between the A46G polymorphism (rs1042713) in the β2-adrenergic receptor gene and essential hypertension susceptibility in the Chinese population: A PRISMA-compliant meta-analysis

BACKGROUND

Recently, many studies have been conducted to investigate the relationship between the A46G polymorphism in the β2-adrenergic receptor (ADRB2) gene and essential hypertension risk in the Chinese population. However, the results of previous studies were conflicting.

OBJECTIVES

The present study aimed to investigate the association between the ADRB2 A46G polymorphism and the risk of essential hypertension in the Chinese population.

METHODS

We performed a systematic search of possible relevant studies on PubMed, Embase, Ovid, Web of Science, China National Knowledge Infrastructure, Wanfang, and China Biology Medicine disc databases up to January 3, 2020. Two authors independently extracted information from included articles and assessed the quality of each study by the use of the Newcastle-Ottawa Scale. According to the extent of interstudy heterogeneity, either a random-effect model or a fixed-effect model was used to calculate the combined odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Finally, 16 studies containing 3390 cases and 2528 controls were included in our meta-analysis. Significant associations were found between the ADRB2 A46G polymorphism and essential hypertension risk in the Chinese population under four genetic models: allele genetic model (OR: 1.14, 95% CI: 1.06-1.23, P = .001, Pheterogeneity = .09), homozygote genetic model (OR: 1.29, 95% CI: 1.11-1.51, P = .001, Pheterogeneity = .25), dominant genetic model (OR: 1.17, 95% CI: 1.05-1.32, P = .005, Pheterogeneity = .04), and recessive genetic model (OR: 1.21, 95% CI: 1.05-1.38, P = .007, Pheterogeneity = .72).

CONCLUSION

The ADRB2 A46G polymorphism may increase the risk of essential hypertension in the Chinese population.

The Roles of Monocyte and Monocyte-Derived Macrophages in Common Brain Disorders

The brain is the most important and complex organ in most living creatures which serves as the center of the nervous system. The function of human brain includes controlling of the motion of the body and different organs and maintaining basic homeostasis. The disorders of the brain caused by a variety of reasons often severely impact the patients' normal life or lead to death in extreme cases. Monocyte is an important immune cell which is often recruited to the brain in a number of brain disorders. However, the role of monocytes may not be simply described as beneficial or detrimental. It significantly depends on the disease models and the stages of disease progression. In this review, we summarized the current knowledge about the role of monocytes and monocyte-derived macrophages during several common brain disorders. Major focuses include ischemic stroke, Alzheimer's disease, multiple sclerosis, intracerebral hemorrhage, and insomnia. The recruitment, differentiation, and function of monocyte in these diseases are reviewed.

Retinal Vascular and Anatomical Features in the Spontaneously Hypertensive Rat

Purpose: To evaluate whether in vivo optical imaging methods and histology can detect comparable vascular and neuronal damage in the retina due to the effects of progressive chronic hypertension on the retinal vasculature and neurons using the spontaneously hypertensive rat (SHR) model at young and old ages. Methods: Male SHR and normotensive Wistar Kyoto (WKY) rats were studied at 10 and 40 weeks of age (n = 6 each group). Arterial blood pressure was measured with a tail-cuff. Under anesthesia, fundus photography was used to measure retinal arterial diameters and optical coherence tomography was used to measure retinal layer thicknesses. Histology was then used to measure microvascular and cell density in different retinal layers. Results: Blood pressure was significantly higher in SHR than WKY in both age groups (p < .05). Fundus images showed no gross abnormalities, hemorrhage, or stenosis in all groups. Retinal vessels, however, appeared more tortuous in SHR compared to WKY at both ages. Retinal vessel diameters in SHR were significantly narrower than in WKY at both age groups (p < .05). Microvascular densities at 10 weeks were not significantly different (p > .05) but were markedly reduced in SHR at 40 weeks compared to WKY (p < .05). The outer nuclear layer thickness of SHR was significantly thinner than that of WKY at both ages (p < .05), consistent with histological cell density measurements (p < .05). The ganglion cell layer and inner nuclear layer thicknesses were not significantly different between SHR and WKY (p > .05), consistent with the corresponding histological cell density measurements (p > .05). Conclusion: In vivo optical imaging showed that systemic hypertension progressively reduces retinal arterial diameter and thicknesses of the outer retina in spontaneously hypertensive rats, with consistent vascular and neuronal findings from histology.

Hypertension and Its Impact on Stroke Recovery: From a Vascular to a Parenchymal Overview

Hypertension is the first modifiable vascular risk factor accounting for 10.4 million deaths worldwide; it is strongly and independently associated with the risk of stroke and is related to worse prognosis. In addition, hypertension seems to be a key player in the implementation of vascular cognitive impairment. Long-term hypertension, complicated or not by the occurrence of ischemic stroke, is often reviewed on its vascular side, and parenchymal consequences are put aside. Here, we sought to review the impact of isolated hypertension or hypertension associated to stroke on brain atrophy, neuron connectivity and neurogenesis, and phenotype modification of microglia and astrocytes. Finally, we discuss the impact of antihypertensive therapies on cell responses to hypertension and functional recovery. This attractive topic remains a focus of continued investigation and stresses the relevance of including this vascular risk factor in preclinical investigations of stroke outcome.

Bioactive Peptide VHVV Upregulates the Long-Term Memory-Related Biomarkers in Adult Spontaneously Hypertensive Rats

Hypertension is one of the growing risk factors for the progression of long-term memory loss. Hypertension-mediated memory loss and treatment remain not thoroughly elucidated to date. Plant-based natural compounds are an alternative solution to treating human diseases without side effects associated with commercial drugs. This study reveals that bioactive peptides extracted from soy hydrolysates mimic hypertension-mediated memory loss and neuronal degeneration and alters the memory molecular pathway in spontaneously hypertensive rats (SHR). The SHR animal model was treated with bioactive peptide VHVV (10 mg/kg/oral administration) and angiotensin-converting-enzyme (ACE) inhibitors (5 mg/kg/oral administration) for 24 weeks. We evaluated molecular level expression of brain-derived neurotrophic factor (BDNF), cAMP response element binding protein (CREB), and survival markers phospho-protein kinase B (P-AKT) and phosphoinositide 3-kinase (PI3K) after 24 weeks of treatment for SHR in this study. Western blotting, hematoxylin and eosin (H&E) staining, and immunohistochemistry showed long-term memory loss and neuronal degeneration in SHR animals. Bioactive peptide VHVV-treated animals upregulated the expression of long-term memory-relate proteins and neuronal survival. Spontaneously hypertensive rats treated with oral administration of bioactive peptide VHVV had activated CREB-mediated downstream proteins which may reduce hypertension-mediated long-term memory loss and maintain neuronal survival.

Hypertension prevents a sensory stimulation-based collateral therapeutic from protecting the cortex from impending ischemic stroke damage in a spontaneously hypersensitive rat model

Assessing potential stroke treatments in the presence of risk factors can improve screening of treatments prior to clinical trials and is important in testing the efficacy of treatments in different patient populations. Here, we test our noninvasive, nonpharmacological sensory stimulation treatment in the presence of the main risk factor for ischemic stroke, hypertension. Utilizing functional imaging, blood flow imaging, and histology, we assessed spontaneously hypertensive rats (SHRs) pre- and post-permanent middle cerebral artery occlusion (pMCAO). Experimental groups included a treatment SHR group (sensory-stimulated group), control untreated SHR group (no sensory stimulation), and a treated (sensory-stimulated) Wistar-Kyoto normotensive group. Unlike our previous studies, which showed sensory-based complete protection from impending ischemic cortical stroke damage in rats as seen in the treated Wistar-Kyoto group, we found that SHRs at 24hr post-pMCAO lacked evoked cortical activation, had a significant reduction in blood flow within the MCA, and sustained very large infarcts regardless of whether they received stimulation treatment. If translatable, this work highlights a potential need for a combined treatment plan when delivering sensory stimulation treatment in this patient population.

Involvement of Epithelial Na+ Channel in the Elevated Myogenic Response in Posterior Cerebral Arteries from Spontaneously Hypertensive Rats

Hypertension is characterized by increased peripheral vascular resistance which is related with elevated myogenic response. Recent findings have indicated that epithelial sodium channel (ENaC) is involved in mechanotransduction of the myogenic response. The purpose of this study was to investigate the involvement of ENaC in the elevated myogenic response of posterior cerebral arteries (PCAs) from spontaneously hypertensive rats (SHRs). Sixteen to eighteen weeks old male wistar kyoto rats (WKYs) and SHRs were used in this study. We found that wall to lumen (W/L) ratio was increased in the PCAs from SHRs compared with WKYs at the resting state. Interestingly, amiloride significantly inhibited myogenic response in the PCAs from SHRs and WKYs, however, the magnitude of the blockade was greater in SHRs. The transfection of γENaC-siRNA significantly reduced the expression of γENaC protein and inhibited myogenic response in the PCAs from SHRs. Furthermore, these data were supported by the findings that serum/glucocorticoid-induced kinase (Sgk1) and neural precursor cell-expressed developmentally downregulated gene 4-2 (Nedd4-2) were increased in SHRs compared with WKYs. Our results suggest that γENaC may play an important role in the elevated myogenic response in PCAs from SHRs.

Peripheral and Cerebral Resistance Arteries in the Spontaneously Hypertensive Heart Failure Rat: Effects of Stilbenoid Polyphenols

Hypertension is associated with aberrant structure and mechanical properties of resistance arteries. We determined the effects of resveratrol, a non-flavonoid polyphenol found in foods such as red grapes, and structurally-similar analogues (pterostilbene and gnetol) on systolic blood pressure (SBP) and resistance arteries from the spontaneously hypertensive heart failure (SHHF) rat. SBP was elevated in 17-week-old SHHF vs. Sprague-Dawley rats (normotensive control; 194 ± 3 vs. 142 ± 6 mmHg, p < 0.01) and was unaffected by resveratrol, pterostilbene, or gnetol (2.5 mg/kg/d). Geometry and mechanical properties of pressurized mesenteric resistance arteries and middle cerebral arteries were calculated from media and lumen dimensions measured at incremental intraluminal pressures. SHHF arteries exhibited remodeling which consisted of augmented media-to-lumen ratios, and this was attenuated by stilbenoid treatment. Compliance was significantly reduced in SHHF middle cerebral arteries but not mesenteric arteries vis-à-vis increased wall component stiffness; stilbenoid treatment failed to normalize compliance and wall component stiffness. Our data suggest that neither AMPK nor ERK mediate stilbenoid effects. In conclusion, we observed arterial bed-specific abnormalities, where mesenteric resistance arteries exhibited remodeling and cerebral arteries exhibited remodeling and stiffening. Resveratrol, pterostilbene, and gnetol exhibited similar abilities to attenuate vascular alterations.

Testing a Model of Sodium Reduction in Hypertensive Older Thai Adults

Hypertensive older adults will benefit if there is a clear understanding of the factors related to sodium reduction. That would raise awareness of the causes, consequently reducing many health risks, lowering health care costs, and diminishing economic and social burden from high blood pressure. This study explored predictors of urinary sodium excretion. A cross-sectional, correlational study was conducted in 312 hypertensive older Thai adults. Questionnaires related to knowledge, self-care agency, self-care behavior of sodium reduction, and 24-hour urinary sodium analyses were used, followed by the application of structural equation modeling and the Analysis of Moment Structures program. Self-care agency, knowledge, self-care behavior, rural/urban location, and education accounted for 61% of urinary sodium excretion. Self-care agency, knowledge, and self-care behavior were the main predictors in the urinary sodium excretion model. This study suggests establishing supportive educative sodium reduction-related programs that improve knowledge and enhance self-care agency, as well as a comparison of the changes of sodium reduction self-care behavior and urinary sodium excretion over time after the intervention.

Hypertension and Dementia: Epidemiological and Experimental Evidence Revealing a Detrimental Relationship

Hypertension and dementia represent two major public health challenges worldwide, notably in the elderly population. Although these two conditions have classically been recognized as two distinct diseases, mounting epidemiological, clinical and experimental evidence suggest that hypertension and dementia are strictly intertwined. Here, we briefly report how hypertension profoundly affects brain homeostasis, both at the structural and functional level. Chronic high blood pressure modifies the cerebral vasculature, increasing the risk of Aβ clearance impairment. The latter, excluding genetic etiologies, is considered one of the main causes of Aβ deposition in the brain. Studies have shown that hypertension induces cerebral arterial stiffening and microvascular dysfunction, thus contributing to dementia pathophysiology. This review examines the existing and the updated literature which has attempted to explain and clarify the relationship between hypertension and dementia at the pathophysiological level.

Ischemic Stroke: Risk Stratification, Warfarin Teatment and Outcome Measure

Stroke is a focal neurological syndrome of vascular basis, which may be due to ischemic thrombo-embolism or intra-cerebral haemorrhage. This condition has to be treated on emergency basis as it may cause an irreversible neurological damage. Warfarin has been a widely used oral anti-coagulant in treating ischemic stroke patients. This review highlights the benefits and challenges of warfarin treatment in stroke patients and discusses about the importance of risk stratification scores and bleeding scores in estimating the bleeding risk associated with warfarin treatment. This review also highlights the use of stroke outcome measures in identifying the patients with post-stroke disabilities to provide patient specific treatment.

Role of the renin-angiotensin system, renal sympathetic nerve system, and oxidative stress in chronic foot shock-induced hypertension in rats

OBJECTIVE

The renin-angiotensin system (RAS) and renal sympathetic nerve system (RSNS) are involved in the development of hypertension. The present study is designed to explore the possible roles of the RAS and the RSNS in foot shock-induced hypertension.

METHODS

Male Sprague-Dawley rats were divided into six groups: control, foot shock, RSNS denervation, denervation plus foot shock, Captopril (angiotensin I converting enzyme inhibitor, ACE inhibitor) plus foot shock, and Tempol (superoxide dismutase mimetic) plus foot shock. Rats received foot shock for 14 days. We measured the quantity of thiobarbituric acid reactive substances (TBARS), corticosterone, renin, and angiotensin II (Ang II) in plasma, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and renal noradrenaline content. RAS component mRNA and protein levels were quantified in the cerebral cortex and hypothalamus.

RESULTS

The two week foot shock treatment significantly increased systolic blood pressure, which was accompanied by an increase in angiotensinogen, renin, ACE1, and AT1a mRNA and protein expression in the cerebral cortex and hypothalamus, an increase of the plasma concentrations of renin, Ang II, corticosterone, and TBARS, as well as a decrease in plasma SOD and GSH-Px activities. Systolic blood pressure increase was suppressed by denervation of the RSNS or treatment with Captopril or Tempol. Interestingly, denervation or Tempol treatment both decreased main RAS components not only in the circulatory system, but also in the central nervous system. In addition, decreased antioxidant levels and increased TBARS and corticosterone levels were also partially restored by denervation or treatment with Tempol or Captopril.

CONCLUSIONS

RAS, RSNS and oxidative stress reciprocally potentiate to play important roles in the development of foot shock-induced hypertension.

Cerebral angiography, blood flow and vascular reactivity in progressive hypertension

Chronic hypertension alters cerebral vascular morphology, cerebral blood flow (CBF), cerebrovascular reactivity, and increses susceptibility to neurological disorders. This study evaluated: i) the lumen diameters of major cerebral and downstream arteries using magnetic resonance angiography, ii) basal CBF, and iii) cerebrovascular reactivity to hypercapnia of multiple brain regions using arterial-spin-labeling technique in spontaneously hypertensive rats (SHR) at different stages. Comparisons were made with age-matched normotensive Wistar Kyoto (WKY) rats. In 10-week SHR, lumen diameter started to reduce, basal CBF, and hypercapnic CBF response were higher from elevated arterial blood pressure, but there was no evidence of stenosis, compared to age-matched WKY. In 20-week SHR, lumen diameter remained reduced, CBF returned toward normal from vasoconstriction, hypercapnic CBF response reversed and became smaller, but without apparent stenosis. In 40-week SHR, lumen diameter remained reduced and basal CBF further decreased, resulting in larger differences compared to WKY. There was significant stenosis in main supplying cerebral vessels. Hypercapnic CBF response further decreased, with some animals showing negative hypercapnic CBF responses in some brain regions, indicative of compromised cerebrovascular reserve. The territory with negative hypercapnia CBF responses corresponded with the severity of stenosis in arteries that supplied those territories. We also found enlargement of downstream vessels and formation of collateral vessels as compensatory responses to stenosis of upstream vessels. The middle cerebral and azygos arteries were amongst the most susceptible to hypertension-induced changes. Multimodal MRI provides clinically relevant data that might be useful to characterize disease pathogenesis, stage disease progression, and monitor treatment effects in hypertension.

Impaired myogenic response and autoregulation of cerebral blood flow is rescued in CYP4A1 transgenic Dahl salt-sensitive rat

We have reported that a reduction in renal production of 20-HETE contributes to development of hypertension in Dahl salt-sensitive (SS) rats. The present study examined whether 20-HETE production is also reduced in the cerebral vasculature of SS rats and whether this impairs the myogenic response and autoregulation of cerebral blood flow (CBF). The production of 20-HETE, the myogenic response of middle cerebral arteries (MCA), and autoregulation of CBF were compared in SS, SS-5(BN) rats and a newly generated CYP4A1 transgenic rat. 20-HETE production was 6-fold higher in cerebral arteries of CYP4A1 and SS-5(BN) than in SS rats. The diameter of the MCA decreased to 70 ± 3% to 65 ± 6% in CYP4A1 and SS-5(BN) rats when pressure was increased from 40 to 140 mmHg. In contrast, the myogenic response of MCA isolated from SS rats did not constrict. Administration of a 20-HETE synthesis inhibitor, HET0016, abolished the myogenic response of MCA in CYP4A1 and SS-5(BN) rats but had no effect in SS rats. Autoregulation of CBF was impaired in SS rats compared with CYP4A1 and SS-5(BN) rats. Blood-brain barrier leakage was 5-fold higher in the brain of SS rats than in SS-5(BN) and SS.CYP4A1 rats. These findings indicate that a genetic deficiency in the formation of 20-HETE contributes to an impaired myogenic response in MCA and autoregulation of CBF in SS rats and this may contribute to vascular remodeling and cerebral injury following the onset of hypertension.

Contribution of the renin-angiotensin system in chronic foot-shock induced hypertension in rats

AIMS

Chronic foot shock has been demonstrated to induce hypertension. The present study was designed to explore whether the renin-angiotensin system (RAS) plays a role in this process and the possible mechanisms involved in chronic-foot-shock-induced hypertension.

MAIN METHODS

Male Sprague-Dawley rats were subjected to a two-week foot shock with or without an angiotensin II (Ang II) type 1 receptor blocker (ARB, candesartan) or an angiotensin I converting enzyme inhibitor (ACEI, captopril). The expression of RAS components in the central nervous and circulatory systems was examined. Antioxidant levels in the plasma were monitored.

KEY FINDINGS

Two-week foot shock significantly increased systolic blood pressure (SBP). Angiotensinogen, angiotensin I converting enzyme (ACE)-1, ACE-2, angiotensin type 1a and type 1b receptors, and vasopressin (VAP) mRNA expression in the cerebral cortex and hypothalamus were increased along with the concentration of renin and Ang II in the plasma; these changes were accompanied by decreased glutathione peroxidase activity and increased lipid peroxidation levels and plasma corticosterone concentrations. Both candesartan and captopril suppressed not only the increases in SBP but also the increases in VAP expression in the hypothalamus and RAS components in the central nervous system and the circulatory system. The decreases in antioxidant levels and the increases in lipid peroxidation and corticosterone levels were also partially reversed by candesartan or captopril treatment.

SIGNIFICANCE

Chronic foot shock increases expression of the main RAS components, which play an important role in the development of high blood pressure through increased VAP levels, oxidative stress levels and stress hormone levels.

Hypertension alters phosphorylation of VASP in brain endothelial cells

Hypertension impairs cerebral vascular function. Vasodilator-stimulated phosphoprotein (VASP) mediates active reorganization of the cytoskeleton via membrane ruffling, aggregation and tethering of actin filaments. VASP regulation of endothelial barrier function has been demonstrated by studies using VASP(-/-) animals under conditions associated with tissue hypoxia. We hypothesize that hypertension regulates VASP expression and/or phosphorylation in endothelial cells, thereby contributing to dysfunction in the cerebral vasculature. Because exercise has direct and indirect salutary effects on vascular systems that have been damaged by hypertension, we also investigated the effect of exercise on maintenance of VASP expression and/or phosphorylation. We used immunohistochemistry, Western blotting and immunocytochemistry to examine the effect of hypertension on VASP expression and phosphorylation in brain endothelial cells in normotensive [Wistar-Kyoto (WKY)] and spontaneously hypertensive (SH) rats under normal and exercise conditions. In addition, we analyzed VASP regulation in normoxia- and hypoxia-induced endothelial cells. Brain endothelial cells exhibited significantly lower VASP immunoreactivity and phosphorylation at the Ser157 residue in SHR versus WKY rats. Exercise reversed hypertension-induced alterations in VASP phosphorylation. Western blotting and immunocytochemistry indicated reduction in VASP phosphorylation in hypoxic versus normoxic endothelial cells. These results suggest that diminished VASP expression and/or Ser157 phosphorylation mediates endothelial changes associated with hypertension and exercise may normalize these changes, at least in part, by restoring VASP phosphorylation.

Examining the Association of Olmesartan and Other Angiotensin Receptor Blockers With Overall and Cause-Specific Mortality

Concerns about an increased cardiovascular risk with the angiotensin receptor blocker, olmesartan, prompted the current study to examine associations between olmesartan and other angiotensin receptor blockers with overall and cause-specific mortalities. We collected patients who started to use losartan, valsartan, irbesartan, candesartan, telmisartan, and olmesartan between January 1, 2004, and December 31, 2009, from Taiwan’s National Health Insurance claims database. Prescribed drug types, dosage, and other clinical information were collected. Overall mortality and cause-specific mortality were ascertained through linkages with Taiwan’s National Death Registry. Two follow-up analyses, labeled intention-to-treat and as-treated, were conducted. A Cox proportional hazard regression model was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) using losartan as the reference group. A total of 690 463 subjects were included, with a mean follow-up ranging from a low of 2.8 years for olmesartan to a high of 4.1 years for irbesartan. Subjects who began with valsartan had a modest but significantly increased risk of overall mortality (HR, 1.04; 95% CI, 1.02–1.06) compared with losartan. Irbesartan (HR, 0.96; 95% CI, 0.94–0.99), candesartan (HR, 0.95; 95% CI, 0.92–0.99), telmisartan (HR, 0.93; 95% CI, 0.90–0.96), and olmesartan (HR, 0.93; 95% CI, 0.88–0.97) were associated with a slightly lower overall mortality risk than losartan. The analysis indicates that the differences in mortality risk among individual angiotensin receptor blockers were only marginal and thus less likely to be clinically important. Although uncontrolled confounding might still exist, olmesartan does not seem to increase cardiovascular risk compared with losartan.

Prevalence of hypertension in china: a cross-sectional study

Aims

The present study aimed to assess the prevalence of hypertension among Chinese adults.

Methods

Data were obtained from sphygmomanometer measurements and a questionnaire administered to 46239 Chinese adults ≥20 years of age who participated in the 2007–2008 China National Diabetes and Metabolic Disorders Study. Hypertension was defined as blood pressure ≥140/90 mm Hg or use of antihypertensive medication.

Results

A total of 26.6% of Chinese adults had hypertension, and a significantly greater number of men were hypertensive than women (29.2% vs 24.1%, p<0.001). The age-specific prevalence of hypertension was 13.0%, 36.7%, and 56.5% among persons aged 20 to 44 years (young people), 45 to 64 years (middle-aged people), and ≥65 years (elderly people), respectively. In economically developed regions, the prevalence of hypertension was significantly higher among rural residents than among urban residents (31.3% vs 29.2%, p = 0.001). Among women or individuals who lived in the northern region, the disparity in the prevalence of hypertension between urban and rural areas disappeared (women: 24.0% vs. 24.0%, p = 0.942; northern region: 31.6% vs. 31.2%, p = 0.505). Among hypertensive patients, 45.0% were aware of their condition, 36.2% were treated, and 11.1% were adequately controlled.

Conclusions

The prevalence of hypertension in China is increasing. The trend of an increase in prevalence is striking in young people and rural populations. Hypertension awareness, treatment, and control are poor. Public health efforts for further improving awareness and enhancing effective control are urgently needed in China, especially in emerging populations.

Multimodal imaging in rats reveals impaired neurovascular coupling in sustained hypertension

BACKGROUND AND PURPOSE

Arterial hypertension is an important risk factor for cerebrovascular diseases, such as transient ischemic attacks or stroke, and represents a major global health issue. The effects of hypertension on cerebral blood flow, particularly at the microvascular level, remain unknown.

METHODS

Using the spontaneously hypertensive rat (SHR) model, we examined cortical hemodynamic responses on whisker stimulation applying a multimodal imaging approach (multiwavelength spectroscopy, laser speckle imaging, and 2-photon microscopy). We assessed the effects of hypertension in 10-, 20-, and 40-week-old male SHRs and age-matched male Wistar Kyoto rats (CTRL) on hemodynamic responses, histology, and biochemical parameters. In 40-week-old animals, losartan or verapamil was administered for 10 weeks to test the reversibility of hypertension-induced impairments.

RESULTS

Increased arterial blood pressure was associated with a progressive impairment in functional hyperemia in 20- and 40-week-old SHRs; baseline capillary red blood cell velocity was increased in 40-week-old SHRs compared with age-matched CTRLs. Antihypertensive treatment reduced baseline capillary cerebral blood flow almost to CTRL values, whereas functional hyperemic signals did not improve after 10 weeks of drug therapy. Structural analyses of the microvascular network revealed no differences between normo- and hypertensive animals, whereas expression analyses of cerebral lysates showed signs of increased oxidative stress and signs of impaired endothelial homeostasis upon early hypertension.

CONCLUSIONS

Impaired neurovascular coupling in the SHR evolves upon sustained hypertension. Antihypertensive monotherapy using verapamil or losartan is not sufficient to abolish this functional impairment. These deficits in neurovascular coupling in response to sustained hypertension might contribute to accelerate progression of neurodegenerative diseases in chronic hypertension.

Death by a thousand cuts in Alzheimer's disease: hypoxia--the prodrome

A wide range of clinical consequences may be associated with obstructive sleep apnea (OSA) including systemic hypertension, cardiovascular disease, pulmonary hypertension, congestive heart failure, cerebrovascular disease, glucose intolerance, impotence, gastroesophageal reflux, and obesity, to name a few. Despite this, 82 % of men and 93 % of women with OSA remain undiagnosed. OSA affects many body systems, and induces major alterations in metabolic, autonomic, and cerebral functions. Typically, OSA is characterized by recurrent chronic intermittent hypoxia (CIH), hypercapnia, hypoventilation, sleep fragmentation, peripheral and central inflammation, cerebral hypoperfusion, and cerebral glucose hypometabolism. Upregulation of oxidative stress in OSA plays an important pathogenic role in the milieu of hypoxia-induced cerebral and cardiovascular dysfunctions. Strong evidence underscores that cerebral amyloidogenesis and tau phosphorylation--two cardinal features of Alzheimer's disease (AD), are triggered by hypoxia. Mice subjected to hypoxic conditions unambiguously demonstrated upregulation in cerebral amyloid plaque formation and tau phosphorylation, as well as memory deficit. Hypoxia triggers neuronal degeneration and axonal dysfunction in both cortex and brainstem. Consequently, neurocognitive impairment in apneic/hypoxic patients is attributable to a complex interplay between CIH and stimulation of several pathological trajectories. The framework presented here helps delineate the emergence and progression of cognitive decline, and may yield insight into AD neuropathogenesis. The global impact of CIH should provide a strong rationale for treating OSA and snoring clinically, in order to ameliorate neurocognitive impairment in aged/AD patients.

Pivotal roles of monocytes/macrophages in stroke

Stroke is an important issue in public health due to its high rates both of morbidity and mortality, and high rate of disability. Hypertension, cardiovascular disease, arterial fibrillation, diabetes mellitus, smoking, and alcohol abuse are all risk factors for stroke. Clinical observations suggest that inflammation is also a direct risk factor for stroke. Patients with stroke have high levels of inflammatory cytokines in plasma, and immune cells, such as macrophages and T-lymphocytes, are noted within stroke lesions. These inflammatory events are considered as a result of stroke. However, recent studies show that plasma levels of inflammatory cytokines or soluble adhesion molecules are high in patients without stroke, and anti-inflammatory therapy is effective at reducing stroke incidence in not only animal models, but in humans as well. Statins have been shown to decrease the stroke incidence via anti-inflammatory effects that are both dependent and independent of their cholesterol-lowering effects. These reports suggest that inflammation might directly affect the onset of stroke. Microglial cells and blood-derived monocytes/macrophages play important roles in inflammation in both onset and aggravation of stroke lesions. We review the recent findings regarding the role of monocytes/macrophages in stroke.

Development and validation of the dietary sodium reduction self-care agency scale

A scale did not exist for measuring the capability or self-care agency of lowering salt consumption in older adults with hypertension. Therefore, our objectives were to develop and validate the Dietary Sodium Reduction Self-Care Agency Scale (DSR-SCA Scale). A 24-item scale was developed and tested in 242 older adults with hypertension. Exploratory factor analysis using principal components extraction, Rasch analysis, and internal consistency reliability were used to evaluate the DSR-SCA Scale. Principal components extraction with Promax rotation was used. An 11-item DSR-SCA Scale with three factor loadings, which measure proficiency, persuasiveness, and resourcefulness, was finalized after it was found to meet the criteria of a minimal factor loading of 0.40, with eigenvalues of 2.20, 1.73, and 1.64, respectively. The Kaiser-Meyer-Olkin was 0.80, and Bartlett's test was significant, χ(2) (df = 55) 403.71, p < 0.0001. The measures accounted for 51% of the total variance. Item infit and outfit mean square ranged from 0.88 to 1.18 and the infit and outfit standardized mean square was -1.8 to 1.7. The 11-item scale demonstrated internal consistency with a Cronbach's alpha coefficient of 0.73 for the total scale. The results showed that the DSR-SCA Scale consisted of three factors that have adequate construct validity and reliability to measure power components and enabling capability related to Orem's self-care theory. This scale is brief, easy-to-complete, and useful for measuring salt reduction self-care agency in older adults with hypertension

From hypertension to stroke: mechanisms and potential prevention strategies

Stroke is a major cause of disability and death worldwide. Prevention aimed at risk factors of stroke is the most effective strategy to curb the stroke pandemic. Hypertension is one of the most important risk factors for stroke. Despite the substantial evidence of the benefits of lowering blood pressure, conventional treatment does not normalize the burden of major cardiovascular events in patients with hypertension. Fully understanding the factors involved in the hypertension-induced stroke helps to develop new strategies for stroke prevention. Antihypertensive therapies selected should have positive blood pressure-independent effects on stroke risk. This review summarizes the factors involved in the hypertension-induced stroke, such as oxidative stress, inflammation, and arterial baroreflex dysfunction, and potential strategies for its prevention, therefore, provides clues for clinicians.

Epidemiology, pathophysiology, and treatment of hypertension in ischaemic stroke patients

Stroke continues to be one of the leading causes of mortality and morbidity worldwide. There are 2 main types of stroke: ischaemic strokes, which are caused by obstruction of the blood vessels leading to or within the brain, and haemorrhagic strokes, which are induced by the disruption of blood vessels. Stroke is a disease of multifactorial aetiology that may develop as an end state in patients with serious vascular conditions--most notably, uncontrolled arterial hypertension--thereby necessitating the effective control of this risk factor to prevent stroke or its recurrence. This paper focuses specifically on the epidemiology and pathogenesis of ischaemic stroke mainly in chronically hypertensive patients and pays particular attention to the efficacy of a select group of routinely used major antihypertensive drugs (i.e., angiotensin-converting enzyme inhibitors, angiotensin II type 1 receptor blockers, and calcium channel blockers) in the treatment of strokes.

Understanding the PRoFESS Study for Secondary Stroke Prevention

The Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial is the largest secondary stroke prevention study completed to date. It compared extended-release dipyridamole plus aspirin (eDYP-ASA) versus clopidogrel and telmisartan versus antihypertensive regimens excluding angiotensin receptor blockers (ARBs). No statistical differences were found in either arm for the primary outcome of fatal or nonfatal stroke or prespecified secondary end points. eDYP-ASA also was associated with increases in major hemorrhagic events but not with statistical increases in combined rates of stroke recurrence or hemorrhage. Despite PRoFESS, the role of ARBs post stroke remains unclear, as concomitant angiotensin-converting enzyme inhibitor use in PRoFESS obscured whether just blood pressure lowering or renin-angiotensin system blockade is important. The resulting interpretation that eDYP-ASA is "not noninferior" has raised questions about how to interpret noninferiority analyses. Also, although the PRoFESS editorialists suggested that aspirin, the historical bystander control, was the "winner," a review of prior antiplatelet studies suggests that the benefits of aspirin, either as combination or monotherapy, are outweighed by its bleeding hazards. The benefits of clopidogrel or eDYP-ASA, compared with aspirin, are small but real, and both remain preferred agents in secondary stroke prevention.

Prestroke proteomic changes in cerebral microvessels in stroke-prone, transgenic[hCETP]-Hyperlipidemic, Dahl salt-sensitive hypertensive rats

Stroke is the third leading cause of death in the United States with high rates of morbidity among survivors. The search to fill the unequivocal need for new therapeutic approaches would benefit from unbiased proteomic analyses of animal models of spontaneous stroke in the prestroke stage. Since brain microvessels play key roles in neurovascular coupling, we investigated prestroke microvascular proteome changes. Proteomic analysis of cerebral cortical microvessels (cMVs) was done by tandem mass spectrometry comparing two prestroke time points. Metaprotein-pathway analyses of proteomic spectral count data were done to identify risk factor-induced changes, followed by QSPEC-analyses of individual protein changes associated with increased stroke susceptibility. We report 26 cMV proteome profiles from male and female stroke-prone and non-stroke-prone rats at 2 months and 4.5 months of age prior to overt stroke events. We identified 1,934 proteins by two or more peptides. Metaprotein pathway analysis detected age-associated changes in energy metabolism and cell-to-microenvironment interactions, as well as sex-specific changes in energy metabolism and endothelial leukocyte transmigration pathways. Stroke susceptibility was associated independently with multiple protein changes associated with ischemia, angiogenesis or involved in blood brain barrier (BBB) integrity. Immunohistochemical analysis confirmed aquaporin-4 and laminin-α1 induction in cMVs, representative of proteomic changes with >65 Bayes factor (BF), associated with stroke susceptibility. Altogether, proteomic analysis demonstrates significant molecular changes in ischemic cerebral microvasculature in the prestroke stage, which could contribute to the observed model phenotype of microhemorrhages and postischemic hemorrhagic transformation. These pathways comprise putative targets for translational research of much needed novel diagnostic and therapeutic approaches for stroke.

Angiotensin II induced cerebral microvascular inflammation and increased blood-brain barrier permeability via oxidative stress

Although hypertension has been implicated in the pathogenesis of vascular disease, its role in inflammatory responses, especially in brain, remains unclear. In this study we found key mechanisms by which angiotensin II (AngII) mediates cerebral microvascular inflammation. C57BL/6 male mice were subjected to slow-pressor dose of AngII infusion using osmotic mini-pumps at a rate of 400 ng/kg/min for 14 days. Vascular inflammation in the brain was evaluated by analysis of leukocyte-endothelial interaction and blood-brain barrier (BBB) permeability. Results from intravital microscopy of pial vessels in vivo, revealed a 4.2 fold (P<0.05, compared to vehicle) increase in leukocyte adhesion on day 4 of AngII infusion. This effect persisted through day 14 of AngII infusion, which resulted in a 2.6 fold (P<0.01, compared to vehicle) increase in leukocyte adhesion. Furthermore, evaluation of BBB permeability by Evans Blue extravasation showed that Ang II significantly affected the BBB, inducing 3.8 times (P<0.05, compared to vehicle) higher permeability. Previously we reported that AngII mediated hypertension promotes oxidative stress in the vasculature. Thus, we used the superoxide scavenger; 4-hydroxy-TEMPO (Tempol) to determine whether AngII via oxidative stress could contribute to higher leukocyte adhesion and increased BBB permeability. Tempol was given via drinking water (2 mmol) on day 4th following Ang II infusion, since oxidative stress increases in this model on day 4. Treatment with Tempol significantly attenuated the increased leukocyte/endothelial interactions and protected the BBB integrity on day 14 of AngII infusion. In conclusion, AngII via oxidative stress increases cerebral microvasculature inflammation and leads to greater immune-endothelial interaction and higher BBB permeability. This finding may open new avenues for the management of nervous system pathology involving cerebrovascular inflammation.

Increasing frequency and burden of cerebral artery atherosclerosis in Korean stroke patients

PURPOSE

Koreans have been undergoing rapid lifestyle changes that may have an effect on patterns of cerebral artery atherosclerosis. This study was aimed at determining the frequency and distribution of atherosclerosis in the cerebral arteries and associated temporal changes over the past eight-year period among Korean stroke patients.

MATERIALS AND METHODS

By using stroke registry data registered between April 1999 and March 2007, we investigated the presence, severity, and location of cerebral artery atherosclerosis as determined by angiographic findings. Their annual patterns and association with vascular risk factors were investigated.

RESULTS

Of 1,955 patients, 1,517 patients (77.6%) demonstrated atherosclerosis in one or more arteries. A significantly increasing trend of atherosclerosis was observed during the past eight years, which was ascribed to an increase of combined extracranial (EC) and intracranial (IC) atherosclerosis. The number of atherosclerotic arteries increased as the number of risk factors increased. In the multivariate analysis, the year and vascular risk factors were independent predictors of the presence of atherosclerosis.

CONCLUSION

We found that the atherosclerotic burden has been increasing for the past eight years in Korean stroke patients, particularly the combined EC and IC subtype. Lifestyle changes and increase in vascular risk factors may be contributing factors.

Management of essential hypertension

INTRODUCTION

Epidemiological studies have unequivocally shown that hypertension (HT)is a major cardiovascular (CV) risk factor and that a direct linear relationship exists between the severity of the blood pressure (BP) elevation and the occurrence of CV events.

AREAS OF AGREEMENT AND CONTROVERSY

The beneficial effects of the BP-lowering interventions have been recognized since a number of years. These include not only the reduction in CV morbidity and mortality but also the regression (or the delay of progression) of HT-related end-organ damage, such as left ventricular hypertrophy, vascular remodelling, endothelial dysfunction and renal damage. Along with these well-established features, antihypertensive drug treatment still faces a number of unmet goals and unanswered questions, such as the target BP values to achieve in high-risk patients, the threshold of treatment in low-risk patients as well as the choice of the therapeutic approach more likely to offer greater CV protection.

CONCLUSION

Despite unmet goals, antihypertensive treatment has provided throughout the years successful results. Future efforts will be need to achieve a better BP control in the population and thus to obtain a greater CV protection.

Estrous cycle-dependent neurovascular dysfunction induced by angiotensin II in the mouse neocortex

Female mice are protected from the cerebrovascular dysfunction induced by angiotensin II (Ang II), an effect attributed to estrogen. We examined whether such cerebrovascular protection from Ang II is related to the estrous cycle. Cerebral blood flow was monitored by laser-Doppler flowmetry in anesthetized (urethane-chloralose) C57BL/6 female mice equipped with a cranial window. The phase of the estrous cycle was determined by vaginal smear cytology and plasma estrogen measurement. Ang II (0.25 microg/kg per minute, IV, 30 to 45 minutes) elevated arterial pressure (15 to 20 mm Hg) equally across the estrous cycle. However, in proestrus and estrus, phases in which estrogen is relatively high, Ang II did not impair the increase in the cerebral blood flow induced by neural activity or by endothelium-dependent vasodilators (P>0.05 from vehicle). In contrast, in diestrus (lower estrogen), Ang II induced a marked cerebrovascular dysfunction comparable to that of male mice. For example, the cerebral blood flow responses to whisker stimulation and to the endothelium-dependent vasodilator acetylcholine were attenuated by 41+/-12% and 49+/-12%, respectively (P<0.05; n=6 per group). The protection from the cerebrovascular effects of Ang II in proestrus was abolished by the estrogen receptor inhibitor ICI182,780. Ang II also increased production of free radicals in cerebral blood vessels in diestrus (+116+/-13%; P<0.05) but not in proestrus and estrus (P>0.05 from control). Topical treatment with ICI182,780 reestablished Ang II-induced oxidative stress in proestrus (P>0.05 from diestrus). We conclude that the protection from the neurovascular dysfunction induced by acute administration of Ang II in females depends on the estrous cycle and may underlie the increased propensity to cerebrovascular damage associated with low estrogen states.

Early-life sodium exposure unmasks susceptibility to stroke in hyperlipidemic, hypertensive heterozygous Tg25 rats transgenic for human cholesteryl ester transfer protein

BACKGROUND

Early-life risk factor exposure increases aortic atherosclerosis and blood pressure in humans and animal models; however, limited insight has been gained as to end-organ complications.

METHODS AND RESULTS

We investigated the effects of early-life Na exposure (0.23% versus 0.4% NaCl regular rat chow) on vascular disease outcomes using the inbred, transgenic [hCETP](25) Dahl salt-sensitive hypertensive rat model of male-predominant coronary atherosclerosis, Tg25. Rather than the expected increase in coronary heart disease, fetal 0.4% Na exposure (< or =2 g of Na per 2-kcal/d diet) induced adult-onset stroke in both sexes (ANOVA P<0.0001), with earlier stroke onset in Tg25 females. Analysis of later onset of 0.4% Na exposure resulted in decreased stroke risk and later stroke onset despite longer 0.4% Na exposure durations, which indicates increasing risk with earlier onset of 0.4% Na exposure. Histological analysis of stroke-positive rat brains revealed cerebral cortical hemorrhagic infarctions, microhemorrhages, neuronal ischemia, and microvascular injury. Ex vivo MRI of stroke-positive rat brains detected cerebral hemorrhages, microhemorrhages, and ischemia with middle cerebral artery distribution and cerebellar noninvolvement. Ultrasound microimaging detected carotid artery disease. Prestroke analysis detected neuronal ischemia and decreased mass of isolated cerebral but not cerebellar microvessels.

CONCLUSIONS

Early-life Na exposure exacerbated hypertension and unmasked stroke susceptibility, with greater female vulnerability in hypertensive, hyperlipidemic Tg25 rats. The reproducible modeling in stroke-prone Tg25 rats of carotid artery disease, cerebral hemorrhagic infarctions, neuronal ischemia, microhemorrhages, and microvascular alterations suggests a pathogenic spectrum with causal interrelationships. This "mixed-stroke" spectrum could represent paradigms of ischemic-hemorrhagic transformation and/or a microangiopathic basis for the association of ischemic lesions, microhemorrhages, and strokes in humans. Together, the data reveal early-life Na exposure to be a significant modifier of hypertension and stroke disease course and hence a potentially modifiable prevention target that deserves systematic study.

Combining RAAS and calcium channel blockade: ACCOMPLISH in perspective

The Avoiding Cardiovascular events through COMbination therapy in Patients LIving with Systolic Hypertension (ACCOMPLISH) trial was the first trial to compare the cardiovascular outcomes of initial fixed-dose combination angiotensin-converting enzyme inhibitor (ACEI)/calcium channel blocker (CCB) and ACEI/diuretic therapy in patients with hypertension and high risk of cardiovascular events. The initial combination therapy was effective in this population, with ACEI/CCB therapy providing the greatest benefit (reduction in risk of cardiovascular events). Whether or not the findings of ACCOMPLISH can be applied to other renin-angiotensin-aldosterone system (RAAS) inhibitor/CCB combinations, such as angiotensin receptor blocker (ARB)/CCB combinations, has yet to be investigated. The present report reviews the results of ACCOMPLISH, data from trials comparing ARB and ACEI therapies, and findings from studies of ARB/CCB combination therapy that support the use and further study of combination therapy with RAAS inhibitors and CCBs.

Hypertension and cerebrovascular dysfunction

Essential hypertension has devastating effects on the brain, being the major cause of stroke and a leading cause of dementia. Hypertension alters the structure of cerebral blood vessels and disrupts intricate vasoregulatory mechanisms that assure an adequate blood supply to the brain. These alterations threaten the cerebral blood supply and increase the susceptibility of the brain to ischemic injury as well as Alzheimer's disease. This review focuses on the mechanisms by which hypertension disrupts cerebral blood vessels, highlighting recent advances and outstanding issues.