Effect of losartan in aging-related endothelial impairment

Angiotensin-(1-7), a protective peptide against vascular aging

Vascular aging is a complex and multifaceted process that provokes profound molecular, structural, and functional changes in the vasculature. Eventually, these profound aging alterations make arteries more prone to vascular disease, including hypertension, atherosclerosis and other arterial complications that impact the organism beyond the cardiovascular system and accelerate frailty. For these reasons, preventing or delaying the hallmarks of vascular aging is nowadays a major health goal, especially in our aged societies. In this context, angiotensin(Ang)-(1-7), a major player of the protective branch of the renin-angiotensin system, has gained relevance over recent years as growing knowledge on its anti-aging properties is being unveiled. Here, we briefly review the main actions of Ang-(1-7) against vascular aging. These include protection against vascular cell senescence, anti-inflammatory and antioxidant effects together with the induction of cytoprotective systems. Ang-(1-7) further ameliorates endothelial dysfunction, a hallmark of vascular aging and disease, attenuates fibrosis and calcification and promotes protective angiogenesis and repair. Although further research is needed to better understand the anti-aging properties of Ang-(1-7) on the vasculature, this heptapeptide arises as a promising pharmacological tool for preventing vascular aging and frailty.

Angiotensin Receptor Blockers Are Not Just for Hypertension Anymore

Beyond blood pressure control, angiotensin receptor blockers reduce common injury mechanisms, decreasing excessive inflammation and protecting endothelial and mitochondrial function, insulin sensitivity, the coagulation cascade, immune responses, cerebrovascular flow, and cognition, properties useful to treat inflammatory, age-related, neurodegenerative, and metabolic disorders of many organs including brain and lung.

Angiotensin II type 1 receptor is involved in flow-induced vasomotor responses of isolated middle cerebral arteries: role of oxidative stress

This study aimed to determine the mechanosensing role of angiotensin II type 1 receptor (AT1R) in flow-induced dilation (FID) and oxidative stress production in middle cerebral arteries (MCA) of Sprague-Dawley rats. Eleven-week old, healthy male Sprague-Dawley rats on a standard diet were given the AT1R blocker losartan (1 mg/mL) in drinking water (losartan group) or tap water (control group) ad libitum for 7 days. Blockade of AT1R attenuated FID and acetylcholine-induced dilation was compared with control group. Nitric oxide (NO) synthase inhibitor Nω-nitro-l-arginine methyl ester (l-NAME) and cyclooxygenase inhibitor indomethacin (Indo) significantly reduced FID in control group. The attenuated FID in losartan group was further reduced by Indo only at Δ100 mmHg, whereas l-NAME had no effect. In losartan group, Tempol (a superoxide scavenger) restored dilatation, whereas Tempol + l-NAME together significantly reduced FID compared with restored dilatation with Tempol alone. Direct fluorescence measurements of NO and reactive oxygen species (ROS) production in MCA, in no-flow conditions revealed significantly reduced vascular NO levels with AT1R blockade compared with control group, whereas in flow condition increased the NO and ROS production in losartan group and had no effect in the control group. In losartan group, Tempol decreased ROS production in both no-flow and flow conditions. AT1R blockade elicited increased serum concentrations of ANG II, 8-iso-PGF2α, and TBARS, and decreased antioxidant enzyme activity (SOD and CAT). These results suggest that in small isolated cerebral arteries: 1) AT1 receptor maintains dilations in physiological conditions; 2) AT1R blockade leads to increased vascular and systemic oxidative stress, which underlies impaired FID.NEW & NOTEWORTHY The AT1R blockade impaired the endothelium-dependent, both flow- and acetylcholine-induced dilations of MCA by decreasing vascular NO production and increasing the level of vascular and systemic oxidative stress, whereas it mildly influenced the vascular wall inflammatory phenotype, but had no effect on the systemic inflammatory response. Our data provide functional and molecular evidence for an important role of AT1 receptor activation in physiological conditions, suggesting that AT1 receptors have multiple biological functions.

Are losartan and imatinib effective against SARS-CoV2 pathogenesis? A pathophysiologic-based in silico study

Proposing a theory about the pathophysiology of cytokine storm in COVID19, we were to find the potential drugs to treat this disease and to find any effect of these drugs on the virus infectivity through an in silico study. COVID-19-induced ARDS is linked to a cytokine storm phenomenon not explainable solely by the virus infectivity. Knowing that ACE2, the hydrolyzing enzyme of AngII and SARS-CoV2 receptor, downregulates when the virus enters the host cells, we hypothesize that hyperacute AngII upregulation is the eliciting factor of this ARDS. We were to validate this theory through reviewing previous studies to figure out the role of overzealous activation of AT1R in ARDS. According to this theory losartan may attenuate ARDS in this disease. Imatinib, has previously been elucidated to be promising in modulating lung inflammatory reactions and virus infectivity in SARS and MERS. We did an in silico study to uncover any probable other unconsidered inhibitory effects of losartan and imatinib against SARS-CoV2 pathogenesis. Reviewing the literature, we could find that over-activation of AT1R could explain precisely the mechanism of cytokine storm in COVID19. Our in silico study revealed that losartan and imatinib could probably: (1) decline SARS-CoV2 affinity to ACE2. (2) inhibit the main protease and furin, (3) disturb papain-like protease and p38MAPK functions. Our reviewing on renin-angiotensin system showed that overzealous activation of AT1R by hyper-acute excess of AngII due to acute downregulation of ACE2 by SARS-CoV2 explains precisely the mechanism of cytokine storm in COVID-19. Besides, based on our in silico study we concluded that losartan and imatinib are promising in COVID19.

Candesartan Neuroprotection in Rat Primary Neurons Negatively Correlates with Aging and Senescence: a Transcriptomic Analysis

Preclinical experiments and clinical trials demonstrated that angiotensin II AT₁ receptor overactivity associates with aging and cellular senescence and that AT₁ receptor blockers (ARBs) protect from age-related brain disorders. In a primary neuronal culture submitted to glutamate excitotoxicity, gene set enrichment analysis (GSEA) revealed expression of several hundred genes altered by glutamate and normalized by candesartan correlated with changes in expression in Alzheimer's patient's hippocampus. To further establish whether our data correlated with gene expression alterations associated with aging and senescence, we compared our global transcriptional data with additional published datasets, including alterations in gene expression in the neocortex and cerebellum of old mice, human frontal cortex after age of 40, gene alterations in the Werner syndrome, rodent caloric restriction, Ras and oncogene-induced senescence in fibroblasts, and to tissues besides the brain such as the muscle and kidney. The most significant and enriched pathways associated with aging and senescence were positively correlated with alterations in gene expression in glutamate-injured neurons and, conversely, negatively correlated when the injured neurons were treated with candesartan. Our results involve multiple genes and pathways, including CAV1, CCND1, CDKN1A, CHEK1, ICAM1, IL-1B, IL-6, MAPK14, PTGS2, SERPINE1, and TP53, encoding proteins associated with aging and senescence hallmarks, such as inflammation, oxidative stress, cell cycle and mitochondrial function alterations, insulin resistance, genomic instability including telomere shortening and DNA damage, and the senescent-associated secretory phenotype. Our results demonstrate that AT₁ receptor blockade ameliorates central mechanisms of aging and senescence. Using ARBs for prevention and treatment of age-related disorders has important translational value.

Role of endothelial NAD+ deficiency in age-related vascular dysfunction

Age-related alterations in endothelium and the resulting vascular dysfunction critically contribute to a range of pathological conditions associated with old age. To develop therapies rationally that improve vascular health and thereby increase health span and life span in older adults, it will be essential to understand the cellular and molecular mechanisms contributing to vascular aging. Preclinical studies in model organisms demonstrate that NAD+ availability decreases with age in multiple tissues and that supplemental NAD+ precursors can ameliorate many age-related cellular impairments. Here, we provide a comprehensive overview of NAD+-dependent pathways [including the NAD+-using silent information regulator-2-like enzymes and poly(ADP-ribose) polymerase enzymes] and the potential consequences of endothelial NAD+ deficiency in vascular aging. The multifaceted vasoprotective effects of treatments that reverse the age-related decline in cellular NAD+ levels, as well as their potential limitations, are discussed. The preventive and therapeutic potential of NAD+ intermediates as effective, clinically relevant interventions in older adults at risk for ischemic heart disease, vascular cognitive impairment, and other common geriatric conditions and diseases that involve vascular pathologies (e.g., sarcopenia, frailty) are critically discussed. We propose that NAD+ precursors [e.g., nicotinamide (Nam) riboside, Nam mononucleotide, niacin] should be considered as critical components of combination therapies to slow the vascular aging process and increase cardiovascular health span.

Recent Progress in Vascular Aging: Mechanisms and Its Role in Age-related Diseases

As with many age-related diseases including vascular dysfunction, age is considered an independent and crucial risk factor. Complicated alterations of structure and function in the vasculature are linked with aging hence, understanding the underlying mechanisms of age-induced vascular pathophysiological changes holds possibilities for developing clinical diagnostic methods and new therapeutic strategies. Here, we discuss the underlying molecular mediators that could be involved in vascular aging, e.g., the renin-angiotensin system and pro-inflammatory factors, metalloproteinases, calpain-1, monocyte chemoattractant protein-1 (MCP-1) and TGFβ-1 as well as the potential roles of testosterone and estrogen. We then relate all of these to clinical manifestations such as vascular dementia and stroke in addition to reviewing the existing clinical measurements and potential interventions for age-related vascular dysfunction.

Flow-Mediated Dilation and Neurocognition: Systematic Review and Future Directions

BACKGROUND

Previous literature indicates that flow-mediated dilation (FMD) is associated with impaired cognition among patients with stroke. The relationship between FMD and cognition in individuals without cerebrovascular disease has yet to be systematically reviewed.

METHODS

The literature was searched using MEDLINE. Exclusion criteria were as follows: focus on neurological disease (e.g., stroke), animal studies, no quantitative measure of endothelial function or cognition, newborn studies, articles with no original data, and articles that are irrelevant to the topic of interest. Neurocognitive tests were categorized in the following domains: executive function, memory (general, working, episodic/semantic, verbal, visual), global cognitive function, information processing speed, language, psychomotor speed, and visual-spatial ability.

RESULTS

The search yielded 700 articles, of which 10 articles, consisting of 2791 participants, met the criteria for inclusion. Most studies conclude that impaired FMD is associated with poorer neuropsychological functioning, particularly in executive functioning (effect sizes: r = 0.07-0.58) and working memory tasks (effect sizes: r = 0.19-0.39). No association was found between other subdomains of memory and FMD. Visual spatial tasks, information processing speed, language tasks, and global cognition were not associated with FMD overall; however fewer studies examined these domains.

CONCLUSIONS

Even in the absence of cerebrovascular disease, there are links between cognition, particularly executive tasks, and vascular function. Public health implications include the potential value of examining FMD as a predictor of cognitive decline, as well as the potential value of improving cognition through pharmacological and behavioral interventions that improve vascular function. Future studies incorporating neuroimaging measures of cerebral blood flow are warranted.

You're only as old as your arteries: translational strategies for preserving vascular endothelial function with aging

Endothelial dysfunction develops with age and increases the risk of age-associated vascular disorders. Nitric oxide insufficiency, oxidative stress, and chronic low-grade inflammation, induced by upregulation of adverse cellular signaling processes and imbalances in stress resistance pathways, mediate endothelial dysfunction with aging. Healthy lifestyle behaviors preserve endothelial function with aging by inhibiting these mechanisms, and novel nutraceutical compounds that favorably modulate these pathways hold promise as a complementary approach for preserving endothelial health.

Effect of Angiotensin Receptor Blockers on Flow-Mediated Vasodilation: A Meta-Analysis of Randomized Controlled Trials

Background: In a meta-analysis, we investigated the effects of angiotensin receptor blockers (ARBs) in comparison to placebo or other classes of antihypertensive drugs on endothelial function, which was measured by brachial flow-mediated vasodilation (FMD). Methods: We searched for randomized controlled trials that compared ARBs with placebo or other classes of antihypertensive drugs in improving FMD. A random-effect model was used to compute pooled estimates. Results: In 13 trials (n = 529), ARBs were more efficacious in improving brachial FMD than placebo [pooled weighted mean change difference (WMD) 1.34%, 95% CI, 0.93-1.75%, p < 0.001]. In 15 trials (n = 918), treatment with ARBs had a significant effect on brachial FMD when compared with other antihypertensive drugs (pooled WMD 0.59%, 95% CI, 0.20-0.98%, p = 0.003 with significant heterogeneity). ARBs were also more efficacious in improving brachial FMD than calcium channel blockers (CCBs; pooled WMD 1.61%, 95% CI, 0.72-2.49%, p < 0.001) but not the other classes of drugs (p ≥ 0.072). Conclusions: This meta-analysis shows that ARBs improve brachial FMD, a marker of endothelial function, and that they are superior to placebo and CCBs. There was no significant difference in the effect on brachial FMD between ARBs and the other antihypertensive drugs.

Oxidative stress and vascular inflammation in aging

Vascular aging, a determinant factor for cardiovascular disease and health status in the elderly, is now viewed as a modifiable risk factor. Impaired endothelial vasodilation is a early hallmark of arterial aging that precedes the clinical manifestations of vascular dysfunction, the first step to cardiovascular disease and influencing vascular outcomes in the elderly. Accordingly, the preservation of endothelial function is thought to be an essential determinant of healthy aging. With special attention on the effects of aging on the endothelial function, this review is focused on the two main mechanisms of aging-related endothelial dysfunction: oxidative stress and inflammation. Aging vasculature generates an excess of the reactive oxygen species (ROS), superoxide and hydrogen peroxide, that compromise the vasodilatory activity of nitric oxide (NO) and facilitate the formation of the deleterious radical, peroxynitrite. Main sources of ROS are mitochondrial respiratory chain and NADPH oxidases, although NOS uncoupling could also account for ROS generation. In addition, reduced antioxidant response mediated by erythroid-2-related factor-2 (Nrf2) and downregulation of mitochondrial manganese superoxide dismutase (SOD2) contributes to the establishment of chronic oxidative stress in aged vessels. This is accompanied by a chronic low-grade inflammatory phenotype that participates in defective endothelial vasodilation. The redox-sensitive transcription factor, nuclear factor-κB (NF-κB), is upregulated in vascular cells from old subjects and drives a proinflammatory shift that feedbacks oxidative stress. This chronic NF-κB activation is contributed by increased angiotensin-II signaling and downregulated sirtuins and precludes adequate cellular response to acute ROS generation. Interventions targeted to recover endogenous antioxidant capacity and cellular stress response rather than exogenous antioxidants could reverse oxidative stress-inflammation vicious cycle in vascular aging. Lifestyle attitudes such as caloric restriction and exercise training appear as effective ways to overcome defective antioxidant response and inflammation, favoring successful vascular aging and decreasing the risk for cardiovascular disease.

Increased inflammatory biomarkers in hypertensive type 2 diabetic patients: improvement after angiotensin II type 1 receptor blockade

Diabetes and hypertension increasingly are recognized as pro-inflammatory conditions. We tested the hypothesis that in patients with hypertension and type 2 diabetes, blood pressure (BP) reduction with an angiotensin receptor blocker (ARB), valsartan, or with a beta blocker, atenolol, is associated with a decreased inflammatory response. Normotensive subjects and hypertensive patients with type 2 diabetes (40 to 70 years of age) participated in the study. Patients (n = 28) were randomized to double-blind treatment for 1 year with valsartan (80-160 mg) or atenolol (50-100 mg) daily, added to previous therapy. Age-matched controls (n = 12) were also studied. Serum levels of cytokines (IL-6, IL-18), chemokines (MCP-1), and adhesion molecules (sICAM, sE-selectin) were measured by enzyme-linked immunosorbent assay (ELISA) as indices of systemic and vascular inflammation, before and 1 year after treatment. BP was similarly reduced by valsartan and atenolol. Glycemic control and lipid profiles were comparable in the two groups and did not change significantly with antihypertensive therapy. Serum levels of all inflammatory markers were increased in patients before treatment (by two- to four-fold vs. controls, P < .05). IL-6, IL-18, sICAM, and MCP-1 levels were reduced by valsartan (three-fold, P < .05). Only IL-18 was reduced by atenolol compared with pretreatment levels (P < .05). These data indicate that proinflammatory mediators are significantly increased in hypertensive type 2 diabetic patients and that despite similar BP lowering by valsartan and atenolol and similar glucose levels in both treated groups, global inflammatory status was improved only in the valsartan group. Our findings suggest that antihypertensive treatment, particularly with an ARB, ameliorates inflammatory processes in diabetic hypertensive patients. Such effects, which are independent of BP and glycemic control, may contribute to cardiovascular protection.

Mechanisms involved in the aging-induced vascular dysfunction

Vascular aging is a key process determining health status of aged population. Aging is an independent cardiovascular risk factor associated to an impairment of endothelial function, which is a very early and important event leading to cardiovascular disease. Vascular aging, formerly being considered an immutable and inexorable risk factor, is now viewed as a target process for intervention in order to achieve a healthier old age. A further knowledge of the mechanisms underlying the age-related vascular dysfunction is required to design an adequate therapeutic strategy to prevent or restore this impairment of vascular functionality. Among the proposed mechanisms that contribute to age-dependent endothelial dysfunction, this review is focused on the following aspects occurring into the vascular wall: (1) the reduction of nitric oxide (NO) bioavailability, caused by diminished NO synthesis and/or by augmented NO scavenging due to oxidative stress, leading to peroxynitrite formation (ONOO(-)); (2) the possible sources involved in the enhancement of oxidative stress; (3) the increased activity of vasoconstrictor factors; and (4) the development of a low-grade pro-inflammatory environment. Synergisms and interactions between all these pathways are also analyzed. Finally, a brief summary of some cellular mechanisms related to endothelial cell senescence (including telomere and telomerase, stress-induced senescence, as well as sirtuins) are implemented, as they are likely involved in the age-dependent endothelial dysfunction, as well as in the lower vascular repairing capacity observed in the elderly. Prevention or reversion of those mechanisms leading to endothelial dysfunction through life style modifications or pharmacological interventions could markedly improve cardiovascular health in older people.

Evaluation of systemic microvascular endothelial function using laser speckle contrast imaging

OBJECTIVE

The aim of this study was to compare cutaneous microvascular function in young healthy subjects (n=50) with that of cardiometabolic diseased patients (n=50) using laser speckle contrast imaging (LSCI) coupled with transdermal iontophoretic delivery of acetylcholine (ACh) and post-occlusive reactive hyperemia (PORH).

METHODS

Cutaneous blood flow was assessed in the forearm using LSCI at rest, during PORH and during iontophoresis of ACh with increasing anodal currents of 30, 60, 90, 120, 150 and 180 μA during 10-second intervals spaced 1 min apart.

RESULTS

Endothelium-dependent skin microvascular vasodilator responses induced by both ACh and PORH were significantly reduced in cardiometabolic diseased patients compared to healthy subjects. Vasodilator responses induced by ACh were significantly higher in young women than in young men. Iontophoresis charges up to 1.5 mC do not induce nonspecific effects on skin microvascular flux.

CONCLUSION

LSCI appears to be a promising noninvasive technique for evaluating systemic microvascular endothelial function.

Aging and vascular endothelial function in humans

Advancing age is the major risk factor for the development of CVD (cardiovascular diseases). This is attributable, in part, to the development of vascular endothelial dysfunction, as indicated by reduced peripheral artery EDD (endothelium-dependent dilation) in response to chemical [typically ACh (acetylcholine)] or mechanical (intravascular shear) stimuli. Reduced bioavailability of the endothelium-synthesized dilating molecule NO (nitric oxide) as a result of oxidative stress is the key mechanism mediating reduced EDD with aging. Vascular oxidative stress increases with age as a consequence of greater production of reactive oxygen species (e.g. superoxide) without a compensatory increase in antioxidant defences. Sources of increased superoxide production include up-regulation of the oxidant enzyme NADPH oxidase, uncoupling of the normally NO-producing enzyme, eNOS (endothelial NO synthase) (due to reduced availability of the cofactor tetrahydrobiopterin) and increased mitochondrial synthesis during oxidative phosphorylation. Increased bioactivity of the potent endothelial-derived constricting factor ET-1 (endothelin-1), reduced endothelial production of/responsiveness to dilatory prostaglandins, the development of vascular inflammation, formation of AGEs (advanced glycation end-products), an increased rate of endothelial apoptosis and reduced expression of oestrogen receptor α (in postmenopausal females) also probably contribute to impaired EDD with aging. Several lifestyle and biological factors modulate vascular endothelial function with aging, including regular aerobic exercise, dietary factors (e.g. processed compared with non-processed foods), body weight/fatness, vitamin D status, menopause/oestrogen deficiency and a number of conventional and non-conventional risk factors for CVD. Given the number of older adults now and in the future, more information is needed on effective strategies for the prevention and treatment of vascular endothelial aging.

Effects of prasterone (dehydroepiandrosterone) on markers of cardiovascular risk and bone turnover in premenopausal women with systemic lupus erythematosus: a pilot study

DHEA (dehydroepiandrosterone) is a weak androgen with proposed efficacy in the treatment of mild to moderate lupus, and possible beneficial effects on cardiovascular risk and bone mineral density. We hypothesized that treatment with 200 mg a day of Prasterone (DHEA) would improve pre-clinical measures of atherosclerosis: flow-mediated dilatation (FMD), nitroglycerin-mediated dilatation (NMD), and circulating apoptotic endothelial cells (CD 146(AnnV +)), as well markers of bone metabolism. Thirteen premenopausal female patients with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) <or=8 were enrolled in a double-blind placebo-controlled crossover trial for 22 weeks with a 6-week washout between treatment periods. Results reveal high-density lipoprotein (HDL) levels significantly decreased with Prasterone (48.5 versus 56.3 with placebo, p <or= 0.001), and there was a trend towards impairment of endothelial function with Prasterone (brachial artery FMD 3.4% versus 4.4% with placebo, mean difference -1.07, NMD 19.5% versus 24.4% with placebo, mean difference -4.9, p = NS). There were no differences between groups in SLEDAI, CD146( AnnV+) cells, or receptor activator for nuclear factor kB ligand (RANKL)/osteoprotegerin, although RANKL was higher after treatment with Prasterone (mean difference -29.5 units; p = 0.097). This pilot study does not support the use of Prasterone in mild lupus for prevention of atherosclerosis or osteoporosis, and confirms other findings of potentially harmful effects on lipids.

The effect of angiotensin receptor blockers on C-reactive protein and other circulating inflammatory indices in man

Anti-inflammatory properties may contribute to the pharmacological effects of angiotensin II receptor blockers (ARBs), a leading therapeutic class in the management of hypertension and related cardiovascular and renal diseases. That possibility, supported by consistent evidence from in-vitro and animal studies showing pro-inflammatory properties of angiotensin II, has been evaluated clinically by measuring the effect of ARBs on C-reactive protein and other circulating indices of inflammation (e-selectin, adhesion molecules, interleukin-6, tissue necrosis factor-alpha, monocyte chemoattractant protein-1) of potential clinical relevance, a body of evidence that this paper aims to review.

Paradoxical role of angiotensin II type 2 receptors in resistance arteries of old rats

The role of angiotensin II type 2 receptors (AT2Rs) remains a matter of controversy. Its vasodilatory and antitrophic properties are well accepted. Nevertheless, in hypertensive rats, AT2R stimulation induces a vasoconstriction counteracting flow-mediated dilation (FMD). This contraction is reversed by hydralazine. Because FMD is also decreased in aging, another risk factor for cardiovascular diseases, we hypothesized that AT2R function might be altered in old-rat resistance arteries. Mesenteric resistance arteries (250 mum in diameter) were isolated from old (24 months) and control (4 months) rats receiving hydralazine (16 mg/kg per day; 2 weeks) or water. FMD, NO-mediated dilation, and endothelial NO synthase expression were lower in old versus control rats. AT2R blockade improved FMD in old rats, suggesting that AT2R stimulation produced vasoconstriction. AT2R expression was higher in old rats and mainly located in the smooth muscle layer. In old rats, AT2R stimulation induced endothelium-independent contraction, which was suppressed by the antioxidant Tempol. Reactive oxygen species level was higher in old-rat arteries than in controls. Hydralazine improved FMD and NO-dependent dilation in old rats without change in AT2R expression and location. In old rats treated with hydralazine, reactive oxygen species level was reduced in endothelial and smooth muscle cells, and AT2R-dependent contraction was abolished. Thus, AT2R stimulation induced vasoconstriction through activation of reactive oxygen species production, contributing to decrease FMD in old-rat resistance arteries. Hydralazine suppressed AT2R-dependent reactive oxygen species production and AT2R-dependent contraction, improving FMD. Importantly, endothelial alterations in aging were reversible. These findings are important to consider in the choice of vasoactive drugs in aging.

Angiotensin Receptor Blockade Improves Vascular Compliance in Healthy Normotensive Elderly Individuals: Results From a Randomized Double‐Blind Placebo‐Controlled Trial

The renin-angiotensin system (RAS) may play a role in vascular aging. The authors hypothesized that blockade of the angiotensin II type 1 receptor with an angiotensin receptor blocker in healthy elderly subjects improves vascular compliance and endothelial function. Thirty-five healthy elderly subjects were randomized to valsartan or placebo in a double-blind crossover study after baseline testing for pulse wave velocity, aortic augmentation index, and brachial artery flow-mediated dilation. Angiotensin II type 1 receptor blockade with valsartan improved vascular compliance but not flow-mediated dilation. Changes in pulse wave velocity with valsartan were correlated with change in central systolic blood pressure and pulse pressure and remained associated on multivariate analysis. Change in pulse wave velocity after adjusting for degree of blood pressure change, age, and sex remained correlated with assignment to the angiotensin receptor blocker but not placebo. These data suggest that angiotensin II type 1 receptor blockade improves aging-related vascular compliance without alterations in flow-mediated dilation. Mechanisms regulating compliance and endothelial function are complex and may not necessarily converge in aging.

Review of the molecular pharmacology of Losartan and its possible relevance to stroke prevention in patients with hypertension

BACKGROUND

The Losartan Intervention For End-point reduction in hypertension (LIFE) study found that a losartan-based regimen, compared with an atenolol-based regimen, resulted in a significantly lower risk of stroke in hypertensive patients with left ventricular hypertrophy, despite similar reductions in blood pressure.

OBJECTIVE

The purpose of this review was to examine the molecular and pharmacologic mechanisms that may be associated with the different outcomes observed in the LIFE study.

METHODS

A PubMed/MEDLINE search of English-language articles (1990 to February 2006) with the terms angiotensin II antagonists or AIIAs or angiotensin receptor blockers or losartan or atenolol or beta blocker and terms including, but not limited to, atherosclerosis, left ventricular hypertrophy, carotid artery hypertrophy, fatty streaks, atrial fibrillation, arrhythmias, endothelial function, myocyte hypertrophy, myocardial fibrosis, platelet aggregation, tissue factor, plasminogen activator inhibitor-1, PAI-1, anti-inflammatory, uric acid, or oxidative stress.

RESULTS

Losartan's significant effect on stroke may be related to several possible mechanisms that are independent of blood-pressure reductions. These include improvements in endothelial function and vascular structure; decreases in vascular oxidative stress; reductions in left ventricular hypertrophy, reductions in myocardial fibrosis, or both; and modulation of atherosclerotic disease progression. Although some of these effects may be shared by other angiotensin II receptor antagonists (AIIAs), and perhaps other anti-hypertensive classes (eg, angiotensin-converting enzyme inhibitors), the ability of losartan to lower serum uric acid levels-a proposed independent risk factor for cardiovascular disease-appears to be a molecule-specific effect. Alternative explanations of the results of the LIFE study have also been hypothesized, including inappropriate choice of atenolol as an active comparator and differences in central pulse pressures between study groups.

CONCLUSIONS

This review of the literature suggests that losartan (and perhaps other AIIAs) may possess a number of properties, independent of its antihypertensive effects, that may be associated with decreased vulnerability of the plaque, myocardium, and blood.

Plasminogen activator inhibitor-1 is associated with impaired endothelial function in women with systemic lupus erythematosus

Endothelial function, measured noninvasively by brachial artery flow-mediated dilatation (FMD), has been shown to be impaired in patients with systemic lupus erythematosus (SLE). We hypothesized that depressed FMD in SLE patients is associated with increased levels of plasminogen activator inhibitor-1 (PAI-1), an inhibitor of fibrinolysis and regulator of vasoactivity. In this cross-sectional study of female SLE patients under the age of 55, putative markers of cardiovascular disease (CVD) such as PAI-1 were measured in addition to lupus-related disease activity (SLEDAI). The primary outcome, FMD, was measured using high-resolution ultrasound of the brachial artery gated to the R wave to determine endothelial-dependent vasomotion. Endothelial-independent vasomotion was measured in response to nitroglycerin (NMD). Seventy-six female SLE patients, mean age 38.3 +/- 9.4 years, were included. All patients demonstrated normal NMD responses, indicating that depression of FMD was related to decreased endothelial nitric oxide production. Increased PAI-1 was related to depressed FMD by univariate regression (P = 0.004). In a multivariable regression model adjusting for t-PA (tissue plasminogen activator)/PAI-1 ratio, SLEDAI, age at visit, family history of cardiovascular disease, SLE disease duration and body mass index, every 1 ng/mL increase in PAI-1 was associated with a reduction of 0.07 units FMD (P = 0.039). PAI-1 was associated with impaired endothelial dysfunction, after controlling for several potential confounders. Given the high incidence of cardiovascular disease in SLE, further investigation of the role of subclinical markers of CVD is needed.

Blockade of the renin-angiotensin-aldosterone system: a key therapeutic strategy to reduce renal and cardiovascular events in patients with diabetes

Diabetes (particularly type 2 diabetes) represents a global health problem of epidemic proportions. Individuals with diabetes are not only more likely to develop hypertension, dyslipidemia, and obesity, but are also at a significantly higher risk for coronary heart disease, peripheral vascular disease, and stroke. Angiotensin II plays a key pathophysiological role in the progression of diabetic renal disease, and blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II antagonists has therefore become an important therapeutic strategy to reduce renal and cardiovascular events in patients with diabetes. Several studies have demonstrated the effects of angiotensin II antagonists on the reduction of albuminuria and the progression of renal disease from microalbuminuria to macroalbuminuria. More importantly, several endpoint trials have shown that the antiproteinuric effects of losartan and irbesartan translate into cardiovascular and renoprotective benefits beyond blood pressure lowering, thereby delaying the need for dialysis or kidney transplantation by several years. These and other studies indicate that angiotensin II antagonists not only improve survival and quality of life of patients with diabetic nephropathy, but also have the potential to reduce the substantial healthcare burden associated with managing these patients. ACEi also appear to exert similar beneficial effects in diabetic patients, but whether clinically significant differences in renoprotection or mortality exist between angiotensin II antagonists and ACEi in patients with type 2 diabetes remains to be fully investigated in appropriate head-to-head studies.

Renal and vascular hypertension-induced inflammation: role of angiotensin II

PURPOSE OF REVIEW

We will focus on the recent findings concerning the inflammatory response in vascular and renal tissues caused by hypertension.

RECENT FINDINGS

Angiotensin II is one of the main factors involved in hypertension-induced tissue damage. This peptide regulates the inflammatory process. Angiotensin II activates circulating cells, and participates in their adhesion to the activated endothelium and subsequent transmigration through the synthesis of adhesion molecules, chemokines and cytokines. Among the intracellular signals involved in angiotensin II-induced inflammation, the production of reactive oxygen species and the activation of nuclear factor-kappaB are the best known.

SUMMARY

The pharmacological blockade of angiotensin II actions, by angiotensin-converting enzyme inhibitors or angiotensin receptor antagonists, results in beneficial organ protective effects, in addition to the effects of these agents on blood pressure control, that can be explained by the blockade of the angiotensin II-induced pro-inflammatory response. These data provide a rationale for the use of blockers of the renin-angiotensin system to prevent vascular and renal inflammation in patients with hypertension.

Xanthine oxidase does not contribute to impaired peripheral conduit artery endothelium-dependent dilatation with ageing

Vascular oxidative stress is the key mechanism involved in the age-related decline in endothelium-dependent dilatation (EDD). We tested the hypothesis that xanthine oxidase (XO), a major vascular source of reactive oxygen species, contributes to the impairment in EDD with ageing. At baseline, brachial artery flow-mediated dilatation (FMD) was 55% lower in older (n = 9, 64 +/- 2 years, 8M/1F, mean +/- S.E.M.) versus young (n = 9, 26 +/- 1 years, 8M/1F) healthy adults (3.41 +/- 0.44 versus 7.53 +/- 0.67%, P < 0.001), whereas endothelium-independent dilatation (EID; sublingual nitroglycerin) did not differ between groups. Plasma oxidized low-density lipoprotein (oxi-LDL), a measure of systemic oxidative stress, was greater at baseline in the older subjects (58.3 +/- 5.9 versus 46.8 +/- 2.4 U l(-1), P < 0.05) and inversely correlated with baseline FMD (r = - 0.54; P < 0.05). Acute administration of allopurinol, a competitive inhibitor of XO, reduced plasma uric acid concentrations similarly in both groups (P < 0.001), but did not affect FMD, EID, or oxi-LDL in either group. Vascular endothelial protein expression of XO (immunofluorescence) was not different in antecubital venous cells from the young and older subjects (0.56 +/- 0.12 versus 0.68 +/- 0.19 XO intensity/human umbilical vein endothelial cell intensity, P = 0.49). We conclude that XO does not contribute to oxidative stress-associated reductions in peripheral conduit artery EDD with ageing in humans, possibly due to an absence of age-associated up-regulation of endothelial XO.

Opposing actions of angiotensin II type 1 and 2 receptors on plasma cholesterol levels in rats

OBJECTIVE

There have been very few studies to examine how angiotensin II (AII) affects lipid metabolism. We examined the roles of AII type 1 and type 2 receptors (AT1R and AT2R) in cholesterol metabolism in rats fed either normal chow or high-fructose diets.

METHODS AND RESULTS

AII (100 ng/kg per min) or vehicle (saline) was continuously infused through an osmotic mini-pump to normal chow-fed or 60% fructose-fed rats for 2 weeks. AII infusion markedly elevated both the systolic and diastolic blood pressure in the two animal groups. AII did not affect the plasma total cholesterol (TC) in the chow-fed rats. In the AII-infused rats treated with olmesartan medoxomil, an AT1R blocker, we were interested to observe significant decreases in plasma TC and non-high-density lipoprotein (HDL)-cholesterol (C) (TC minus HDL-C), and liver cholesterol content were also decreased. Simultaneous infusion of AII and PD123319, an AT2R blocker, markedly increased non-HDL-C and hepatic cholesterol. The infusion of CGP42112A, an AT2R agonist, decreased non-HDL-C by 30% in normal rats. The AII infusion led to significant elevations in TC and non-HDL-C in the fructose-fed rats, and olmesartan treatment completely rectified this AII-induced hypercholesterolemia.

CONCLUSIONS

These results suggest that the AII receptors exert opposing effects on the plasma cholesterol level; that is, AT1R increases plasma cholesterol while AT2R decreases it. Fructose feeding may selectively augment the action of AT1R and thereby enhance the increase in plasma cholesterol levels in response to AII infusion.

Aggressive antihypertensive therapy based on hydrochlorothiazide, candesartan or lisinopril as initial choice in hypertensive type II diabetic individuals: effects on albumin excretion, endothelial function and inflammation in a double-blind, randomized clinical trial

We investigated the effects of aggressive antihypertensive therapy based on hydrochlorothiazide, candesartan or lisinopril on urinary albumin excretion, endothelial function and inflammatory activity in hypertensive type II diabetic individuals. A total of 70 hypertensive type II diabetic individuals were treated with three antihypertensive strategies in a randomized, double-blind, double-dummy design. Blood pressure was titrated to levels below 130/85 mmHg or a decrease in systolic pressure of 10% with a diastolic pressure below 85 mmHg. After titration, patients were treated for 12 months. Mean blood pressures changed from 157/93, 151/94 and 149/93 at baseline to 135/80, 135/82 and 131/80 mmHg after titration in the hydrochlorothiazide (n=24), candesartan (n=24) and lisinopril (n=22) groups. About 70% reached target blood pressures. However, only 45% had blood pressures <130/85 mmHg. Urinary albumin excretion and levels of soluble vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 decreased (GEE regression coefficients, -2.40 mg/24 h (P<0.001), -85 ng/ml (P=0.01) and -50 ng/ml (P=0.02)), but brachial artery endothelium-dependent and -independent vasodilation and levels of von Willebrand factor and C-reactive protein did not change (GEE regression coefficients, 0.21 mm (P=0.07), 0.04 mm (P=0.43), 0.04 IU/ml (P=0.33) and -1.15 mg/l (P=0.64)). No differences in outcome variables between treatment groups were observed. These data show that achievement of target blood pressures below 130/85 mmHg in hypertensive type II diabetes is difficult. Aggressive antihypertensive therapy can improve urinary albumin excretion, endothelial function and inflammatory activity in hypertensive type II diabetic individuals, regardless of the type of antihypertensive therapy used.

Losartan and simvastatin inhibit platelet activation in hypertensive patients

BACKGROUND

Diabetic patients also show hypercoagulability and platelet hyperaggregability, with increased levels of platelet activation-markers such as P-selectin (CD62P) and platelet-derived microparticles. We investigated the effects of losartan and simvastatin on circulating levels of platelet activation markers, microparticles, soluble selectins, and soluble cell adhesion molecules in hypertensive and hyperlipidemic patients with or without Type 2 diabetes.

METHODS

The subjects included 25 normotensive healthy controls and 41 hypertensive patients. The 41 hypertensive patients were divided into three groups: group A had hypertension and hyperlipidemia (n = 11), group B had hypertension and Type 2 diabetes (n = 14), and group C had hypertension, hyperlipidemia, and diabetes (n = 16). Losartan was administered to all of the patients at a dose of 50 mg/day for 24 weeks. In addition, simvastatin was administered to the hyperlipidemic patients at a dose of 10 mg/day for 24 weeks.

RESULTS

There were significant differences in the levels of CD62P, CD63, PAC-1, platelet microparticles, endothelial microparticles, sE-selectin, and sVCAM-1 between the hypertensive patients and healthy controls. These markers were all significantly increased in hypertensive and hyperlipidemic patients with Type 2 diabetes. In hypertensive patients with diabetes, CD62P, CD63, PAC-1, platelet and endothelial microparticles, and soluble adhesion markers were all decreased by losartan monotherapy. The decrease of each marker in hypertensive and hyperlipidemic patients given combined therapy with losartan plus simvastatin was greater among those with than without Type 2 diabetes. Low-density lipoprotein was decreased significantly by simvastatin and was correlated with CD62P or platelet microparticles in all of the patients.

CONCLUSION

Administration of losartan plus simvastatin to hypertensive and hyperlipidemic patients with Type 2 diabetes may prevent the development of cardiovascular complications caused by activated platelets and microparticles via another mechanism in addition to reduction of the blood pressure or lipid levels.

Valsartan versus ACE inhibition after bare metal stent implantation—results of the VALVACE trial

The use of ACE inhibitors (ACE-i) represents an Ia recommendation in the treatment of patients with STEMI and NSTEMI. However, results of smaller studies suggest an increase of in-stent-restenosis under ACE-i administration. The effects of ACE-i and valsartan after bare metal stent implantation of the culprit type B2/C lesion should be compared. Seven hundred patients were treated either by ACE-i in cases of LVEF<50% or 80 mg valsartan in cases of LVEF> or =50%. Restenosis rates after 6 months were analysed in 399 patients under valsartan and 224 patients under ACE-i with control angiography and major adverse cardiac events (death, infarction, reintervention) in a follow-up of up to 4 (mean 2.6) years in all patients. In-stent-restenosis was found in 19.5% under valsartan and in 34% under ACE-i (p<0.005). In diabetic patients, restenosis occurred in 24% under valsartan and in 43% under ACE-i (p<0.01). In initial acute coronary syndrome (ACS), restenosis rate was 14% under valsartan and 43% under ACE-i (p<0.0001). In stable angina, restenosis rates were 26.5% and 27.5%, respectively. Total MACE rates revealed significant differences in ACS due to reintervention rates of 22% and 7% under ACE-i and valsartan (p<0.0001). The administration of 80 mg valsartan after bare metal stent implantation leads to a reduction of in-stent-restenosis compared to ACE-i. This effect is mainly due to beneficial effects of valsartan in cases with initial ACS. Major differences between ACE-i and valsartan are discussed including inflammation, activation of neutrophils, mode of bradykinin activation, AT2 receptor stimulation and apoptosis of smooth muscle cells.

Angiotensin receptor blockade decreases markers of vascular inflammation

A protective role against atherosclerosis can be attributed to angiotensin converting enzyme inhibitors (ACE-I), since they have been shown to reduce mortality in patients at cardiovascular risk. Since plasma levels of adhesion molecules are considered surrogate markers of endothelial cell activation and atherogenesis, we compared the levels of adhesion molecules after treatment with the ACE-I enalapril or the direct angiotensin- receptor antagonist losartan or placebo. In a randomized, controlled trial, 21 hypercholesterolemic volunteers received 50 mg/d losartan or 20 mg/d enalapril or placebo for twelve weeks. Plasma levels of circulating intercellular adhesion molecule-1 (cICAM-1), vascular adhesion molecule-1 (cVCAM-1), and E-selectin (cE-SEL) were measured by ELISA. Surface expression of ICAM-1 on circulating leukocytes was determined by flow cytometry. Enalapril and losartan but not placebo induced a small but stable decrease of cICAM-1 and cVCAM-1, while cE-SEL and leukocyte expression of ICAM-1 remained unchanged. The lowering of plasma adhesion molecules may indicate an antiatherogenic effect of angiotensin II blockade in hypercholesterolemia. While such preventive effect will have to be proven in clinical trials, our results do not support a preference for either enalapril or losartan with regard to their possible vasoprotective role.

Effects of losartan and simvastatin on monocyte-derived microparticles in hypertensive patients with and without type 2 diabetes mellitus

Monocyte-derived microparticles play an important role in the pathogenesis of diabetic vasculopathy, and angiotensin II receptor blocker and statin have been shown to have a beneficial effect on the angiopathies of hypertension and hyperglycemia in patients with type 2 diabetes mellitus. However, the interaction between angiotensin II receptor blocker and statin, and monocyte-derived microparticles in atherosclerosis is poorly understood. The effects of losartan and simvastatin on circulating concentrations of monocyte-derived microparticles, chemokines, and soluble adhesion markers were studied in hypertensive patients with or without type 2 diabetes mellitus. Monocyte-derived microparticles were measured by flow cytometry, and levels of serum chemokines (MCP-1 and RANTES) and soluble adhesion markers (sP-selectin and sVCAM-1) were measured by enzyme-linked immunosorbent assay. Losartan decreased both the systolic and diastolic blood pressure in hypertensive patients with and without type 2 diabetes mellitus. The concentrations of monocyte-derived microparticles, chemokines, and soluble adhesion molecules were higher in hypertensive patients who also had type 2 diabetes mellitus vs. those who did not. The administration of angiotensin II receptor blocker decreased the circulating concentration of all these markers. In addition, all markers were decreased by combination therapy, and monocyte-derived microparticles were decreased more with combination therapy with losartan and simvastatin than monotherapy with losartan. The administration of angiotensin II receptor blocker inhibited monocyte-derived microparticle generation and suggests that angiotensin II is intimately related to vascular changes that occur in type 2 diabetes mellitus. Combination therapy with a statin and angiotensin II receptor blocker might be valuable as anti-atherosclerotic therapy in patients with type 2 diabetes mellitus and nephropathy.

Endothelial cell apoptosis in systemic lupus erythematosus: a common pathway for abnormal vascular function and thrombosis propensity

Women with systemic lupus erythematosus (SLE) are at risk for premature atherothrombosis independent of Framingham risk factors. We investigated whether endothelial cell (EC) apoptosis predicts abnormal vasomotor tone and contributes to circulating tissue factor (TF) levels in this disease. Brachial artery flow-mediated dilation (FMD) and nitroglycerin-mediated dilation were determined in women with SLE, healthy control subjects, and subjects with coronary artery disease (CAD) (n = 43/group). Quantification of circulating apoptotic ECs was performed by flow cytometry (CD146+ cells that stained for Annexin V [CD146AnnV+]) and immunofluorescent microscopy. Plasma TF was measured by enzyme-linked immunosorbent assay (ELISA). Compared with healthy control and CAD subjects, patients with SLE had higher numbers of circulating CD146AnnV+ cells (10 ± 3, 18 ± 5, and 89 ± 32 cells/mL, respectively, mean ± SEM; P &lt; .01). Increased CD146AnnV+ cells correlated strongly with abnormal vascular function (P = .037). After adjusting for known predictors of endothelial function, CD146AnnV+ was the only variable that predicted FMD (β = –4.5, P &lt; .001). Increased CD146AnnV+ was strongly associated with elevated levels of circulating TF (r = .46, P = .002). Circulating apoptotic ECs are elevated in young women with SLE and strongly correlate with markedly abnormal vascular function and elevated TF levels. Heightened endothelial apoptosis may represent an important mechanism for development of atherothrombosis in SLE.

Interactive effects of the ACE DD polymorphism with the NOS III homozygous G849T (Glu298-->Asp) variant in determining endothelial function in coronary artery disease

The products of nitric oxide synthase (NOS) and angiotensin-converting enzyme (ACE) play a critical role in determining vessel wall structure and function. Polymorphisms in both genes have been independently demonstrated to influence propensity to cardiovascular events. The purpose of this study was to determine the influence of the homozygous G849T (Glu298-->Asp) polymorphism in NOS III on peripheral conduit artery endothelial function and to elucidate the modifier role, if any, of a common ACE polymorphism. Three hundred and ninety-seven consecutive subjects presenting to the cardiac catheterization laboratory of the University of Michigan over a period of 18 months were recruited. DNA was extracted and polymerase chain reaction (PCR) analysis for ACE and NOS polymorphisms performed. Patients with homozygosity for G849T at both loci (TT) who belong to DD and II ACE genotype (groups 1 and 2) and those who are negative for this polymorphism (GG) and belong to either DD or II genotype (groups 3 and 4) were identified. The four groups then underwent determination of conduit endothelial function. Heterozygosity of Glu298-Asp or the ID variant of the ACE were not studied. Median FMD value in the TT-DD group was 0.20 (-3.17, 2.01) compared with 2.23% (-0.29, 4.17) in the GG-II group. Median values in the TT-II and the GG-DD groups were 3.04 (-1.16, 6.61) and 2.46% (-1.83, 6.52) respectively. These values were not statistically significant (p > 0.05 by one-way ANOVA). Median nitroglycerin-mediated dilation in the four groups did not differ between the four groups (p = NS by ANOVA). Atherosclerosis burdens as assessed by angiography were not different across the groups. In conclusion, the homozygous NOS III variant (GG) status does not seem to interact additively with the ACE homozygous DD genotype in determining flow-mediated vasodilation in individuals with established atherosclerosis and pre-existent endothelial dysfunction.

Effects of cilostazol in patients with Raynaud's syndrome

Raynaud's syndrome (RS), which is characterized by recurrent episodes of vasospasm with exposure to cold, may occur alone (primary RS) or in association with connective tissue diseases or other underlying conditions (secondary RS). We investigated the effect of cilostazol on vessel wall responses in RS. Patients were diagnosed (primary or secondary RS associated with connective tissue diseases) and randomized to placebo or cilostazol 100 mg twice daily for 6 weeks in a double-blind manner. Brachial artery vasoreactivity, laser Doppler fluxmetry, and cold pressor testing (CPT) were performed at study initiation and completion. Symptoms were assessed using standardized questionnaires. Forty subjects completed the study (19 with primary RS and 21 with secondary RS). Cilostazol significantly increased the mean brachial artery diameter at 6 weeks (primary RS, p = 0.006; secondary RS, p = 0.06). There was no change in median flow-mediated dilation (FMD) with cilostazol in primary RS (25th, 75th percentiles) (4.06% [2.5, 6.1] to -0.77% [-2.4, 3.4] or secondary RS (2.2% [0.05, 6.3] to 2.95% [1.7, 7.4]). There were no changes in nitroglycerin-mediated dilation or microvascular flow indexes in either cohort. In patients with primary RS, cilostazol treatment yielded a positive change in the slope of brachial responsiveness to CPT (increase of 0.32 mm/min; p = 0.002 vs placebo). Cilostazol treatment remained significantly associated with increased brachial artery diameter when controlling for baseline values (p = 0.018). Cilostazol increased conduit vessel diameter in patients with primary and secondary RS, with a favorable impact on conduit vessel responsiveness to cold in patients with primary RS without affecting microvascular flow or symptoms.

Age-related endothelial dysfunction : potential implications for pharmacotherapy

Aging per se is associated with abnormalities of the vascular wall linked to both structural and functional changes that can take place at the level of the extracellular matrix, the vascular smooth muscle and the endothelium of blood vessels. Endothelial dysfunction is generally defined as a decrease in the capacity of the endothelium to dilate blood vessels in response to physical and chemical stimuli. It is one of the characteristic changes that occur with age, independently of other known cardiovascular risk factors. This may account in part for the increased incidence of cardiovascular events in elderly people that can be reversed by restoring endothelial function. A better understanding of the mechanisms involved and the aetiopathogenesis of this process will help in the search for new therapeutic agents.Age-dependent alteration of endothelium-dependent relaxation seems to be a widespread phenomenon both in conductance and resistance arteries from several species. In the course of aging, there is an alteration in the equilibrium between relaxing and contracting factors released by the endothelium. Hence, there is a progressive reduction in the participation of nitric oxide and endothelium-derived hyperpolarising factor associated with increased participation of oxygen-derived free radicals and cyclo-oxygenase-derived prostanoids. Also, the endothelin-1 and angiotensin II pathways may play a role in age-related endothelial dysfunction. The use of drugs acting at different levels of these signalling cascades, including antioxidant therapy, lipid-lowering drugs and estrogens, seems to be promising.

Increased asymmetric dimethylarginine and endothelin 1 levels in secondary Raynaud's phenomenon: implications for vascular dysfunction and progression of disease

OBJECTIVE

To compare microvascular and macrovascular functions in a cohort of patients with primary and secondary Raynaud's phenomenon (RP) who were matched for demographic, risk factor, and severity profiles.

METHODS

Forty patients with primary or secondary RP matched for vascular risk factors and severity scores underwent testing of endothelial function and cold pressor responsiveness of the brachial artery. Microvascular perfusion of the digital vasculature was assessed using laser Doppler fluxmetry in response to reactive hyperemia. Plasma was assayed for endothelin 1 (ET-1), asymmetric dimethylarginine (ADMA), intercellular adhesion molecule 1, vascular cell adhesion molecule 1 (VCAM-1), and monocyte chemoattractant protein 1 (MCP-1).

RESULTS

Patients with RP had abnormal vasoconstrictor responses to cold pressor tests (CPT) that were similar in primary and secondary RP. There were no differences in median flow-mediated and nitroglycerin-mediated dilation or CPT of the brachial artery in the 2 populations. Patients with secondary RP were characterized by abnormalities in microvascular responses to reactive hyperemia, with a reduction in area under the curve adjusted for baseline perfusion, but not in time to peak response or peak perfusion ratio. Plasma ET-1, ADMA, VCAM-1, and MCP-1 levels were significantly elevated in secondary RP compared with primary RP. There was a significant negative correlation between ET-1 and ADMA values and measures of microvascular perfusion but not macrovascular endothelial function.

CONCLUSION

Secondary RP is characterized by elevations in plasma ET-1 and ADMA levels that may contribute to alterations in cutaneous microvascular function.

Detection of endothelial dysfunction with brachial artery ultrasound scanning

The role of the endothelium in human disease recently has become the focus of intense scientific investigation. Impaired endothelial function is associated with a number of disease states, including cardiovascular disease (CVD) and its major risk factors. Endothelial dysfunction precedes overt vascular disease by years and may itself be a potentially modifiable CVD risk factor. Although no gold standard for the measurement of endothelial function exists, the measurement of flow-mediated dilation (FMD) in the brachial artery, assessed with Doppler ultrasonography, is the most studied method and shows the most promise for clinical application. It is a well-tolerated, noninvasive, and low-risk procedure. Brachial artery FMD after transient vascular occlusion may serve as an index of nitric oxide bioavailability, and its impairment correlates with coronary arterial abnormalities. These factors, with the wide availability of vascular ultrasound scanning in clinical practice, make brachial artery FMD an attractive screening tool for endothelial dysfunction. Present limitations of this procedure include the lack of a consensus definition of normal FMD and the variability among centers in both procedural technique and image analysis. However, these limitations are likely to be overcome with increasing experience and advances in technology, and with further refinements, the measurement of brachial artery FMD will likely become the clinical technique of choice for the evaluation of endothelial disease.

Raised plasma oxidised LDL in acute cerebral infarction

BACKGROUND

The association between oxidised low density lipoprotein (OxLDL) and cerebral infarction is suspected but not established.

OBJECTIVES

To determine whether plasma OxLDL is a useful marker for monitoring oxidative stress in stroke patients.

METHODS

Plasma OxLDL concentrations were determined in 56 stroke patients with cerebral infarction (n = 45) or cerebral haemorrhage (n = 11), and in 19 age matched controls, using a novel sandwich enzyme linked immunosorbent assay.

RESULTS

Compared with the controls (0.130 (0.007) ng/ micro g LDL, mean (SEM)), OxLDL was significantly raised in patients with cerebral infarction (0.245 (0.022); p < 0.0001) but not in those with haemorrhage (0.179 (0.023)). Patients with cortical ischaemic infarcts (n = 22) had higher OxLDL levels than either the controls (p < 0.0001) or the patients with non-cortical ischaemic infarcts (n = 23) (p < 0.001). Increased OxLDL concentrations in patients with cortical infarcts persisted until the third day after stroke onset. The National Institutes of Health stroke scales in patients with cortical infarction were higher than in those with non-cortical infarction (p < 0.01).

CONCLUSIONS

There is a significant association between raised plasma OxLDL and acute cerebral infarction, especially cortical infarction. Plasma OxLDL may reflect oxidative stress in stroke patients.