Valsartan improves fibrinolytic balance in atherosclerotic rabbits

In-silico simulated prototype-patients using TPMS technology to study a potential adverse effect of sacubitril and valsartan

Unveiling the mechanism of action of a drug is key to understand the benefits and adverse reactions of a medication in an organism. However, in complex diseases such as heart diseases there is not a unique mechanism of action but a wide range of different responses depending on the patient. Exploring this collection of mechanisms is one of the clues for a future personalized medicine. The Therapeutic Performance Mapping System (TPMS) is a Systems Biology approach that generates multiple models of the mechanism of action of a drug. Each molecular mechanism generated could be associated to particular individuals, here defined as prototype-patients, hence the generation of models using TPMS technology may be used for detecting adverse effects to specific patients. TPMS operates by (1) modelling the responses in humans with an accurate description of a protein network and (2) applying a Multilayer Perceptron-like and sampling strategy to find all plausible solutions. In the present study, TPMS is applied to explore the diversity of mechanisms of action of the drug combination sacubitril/valsartan. We use TPMS to generate a wide range of models explaining the relationship between sacubitril/valsartan and heart failure (the indication), as well as evaluating their association with macular degeneration (a potential adverse effect). Among the models generated, we identify a set of mechanisms of action associated to a better response in terms of heart failure treatment, which could also be associated to macular degeneration development. Finally, a set of 30 potential biomarkers are proposed to identify mechanisms (or prototype-patients) more prone of suffering macular degeneration when presenting good heart failure response. All prototype-patients models generated are completely theoretical and therefore they do not necessarily involve clinical effects in real patients. Data and accession to software are available at http://sbi.upf.edu/data/tpms/

Role of the renin-angiotensin system in the pathogenesis of intimal hyperplasia: therapeutic potential for prevention of vein graft failure?

The saphenous vein remains the most widely used conduit for peripheral and coronary revascularization despite a high rate of vein graft failure. The most common cause of vein graft failure is intimal hyperplasia. No agents have been proven to be successful for the prevention of intimal hyperplasia in human subjects. The renin-angiotensin system is essential in the regulation of vascular tone and blood pressure in physiologic conditions. However, this system mediates cardiovascular remodeling in pathophysiologic states. Angiotensin II is becoming increasingly recognized as a potential mediator of intimal hyperplasia. Drugs modulating the renin-angiotensin system include angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. These drugs are powerful inhibitors of atherosclerosis and cardiovascular remodeling, and they are first-line agents for management of several medical conditions based on class I evidence that they delay progression of cardiovascular disease and improve survival. Several experimental models have demonstrated that these agents are capable of inhibiting intimal hyperplasia. However, there are no data supporting their role in prevention of intimal hyperplasia in patients with vein grafts. This review summarizes the physiology of the renin-angiotensin system, the role of angiotensin II in the pathogenesis of cardiovascular remodeling, the medical indications for these agents, and the experimental data supporting an important role of the renin-angiotensin system in the pathogenesis of intimal hyperplasia.

Clot lysis time in platelet-rich plasma: method assessment, comparison with assays in platelet-free and platelet-poor plasmas, and response to tranexamic acid

Fibrinolysis dysfunctions cause bleeding or predisposition to thrombosis. Platelets contain several factors of the fibrinolytic system, which could up or down regulate this process. However, the temporal relationship and relative contributions of plasma and platelet components in clot lysis are mostly unknown. We developed a clot lysis time (CLT) assay in platelet-rich plasma (PRP-CLT, with and without stimulation) and compared it to a similar one in platelet-free plasma (PFP) and to another previously reported test in platelet-poor plasma (PPP). We also studied the differential effects of a single dose of tranexamic acid (TXA) on these tests in healthy subjects. PFP- and PPP-CLT were significantly shorter than PRP-CLT, and the three assays were highly correlated (p < 0.0001). PFP- and PPP-, but more significantly PRP-CLT, were positively correlated with age and plasma PAI-1, von Willebrand factor, fibrinogen, LDL-cholesterol, and triglycerides (p < 0.001). All these CLT assays had no significant correlations with platelet aggregation/secretion, platelet counts, and pro-coagulant tests to explore factor X activation by platelets, PRP clotting time, and thrombin generation in PRP. Among all the studied variables, PFP-CLT was independently associated with plasma PAI-1, LDL-cholesterol, and triglycerides and, additionally, stimulated PRP-CLT was also independently associated with plasma fibrinogen. A single 1 g dose of TXA strikingly prolonged all three CLTs, but in contrast to the results without the drug, the lysis times were substantially shorter in non-stimulated or stimulated PRP than in PFP and PPP. This standardized PRP-CLT may become a useful tool to study the role of platelets in clot resistance and lysis. Our results suggest that initially, the platelets enmeshed in the clot slow down the fibrinolysis process. However, the increased clot resistance to lysis induced by TXA is overcome earlier in platelet-rich clots than in PFP or PPP clots. This is likely explained by the display of platelet pro-fibrinolytic effects. Focused research is needed to disclose the mechanisms for the relationship between CLT and plasma cholesterol and its potential pathophysiologic and clinical relevance.

Proxisome proliferator-activated receptor-α mediates high-fat, diet-enhanced daily oscillation of plasminogen activator inhibitor-1 activity in mice

Acute thrombotic events frequently occur in the early morning among hyperlipidemic patients. The activity of plasminogen activator inhibitor-1 (PAI-1), a potent inhibitor of the fibrinolytic system, oscillates daily, and this is considered one mechanism that underlies the morning onset of acute thrombotic events in hyperlipidemia. Although several studies have reported the expression of the PAI-1 gene is under the control of the circadian clock system, the molecular mechanism of the circadian transactivation of PAI-1 gene under hyperlipidemic conditions remains to be elucidated. Here, the authors investigated whether hyperlipidemia induced by a high-fat diet (HFD) enhances the daily oscillation of plasma PAI-1 activity in mice. The mRNA levels of the PAI-1 gene were increased and rhythmically fluctuated with high-oscillation amplitude in the livers of wild-type mice fed with the HFD. Circadian expression of proxisome proliferator-activated receptor-α (PPARα) mRNA was also augmented as well as that of PAI-1. Chromatin immunoprecipitation showed the HFD-induced hyperlipidemia significantly increased the binding of PPARα to the PAI-1 promoter. Luciferase reporter analysis using primary hepatocytes revealed CLOCK/BMAL1-mediated PAI-1 promoter activity was synergistically enhanced by cotransfection with PPARα/retinoid X receptor-α (RXRα), and this synergistic transactivation was repressed by negative limbs of the circadian clock, PERIOD2 and CRYPTOCHROME1. As expected, HFD-induced PAI-1 mRNA expression was significantly attenuated in PPARα-null mice. These results suggest a molecular link between the circadian clock and lipid metabolism system in the regulation of PAI-1 gene expression, and provide an aid for understanding why hyperlipidemia increases the risk of acute thrombotic events in the morning.

Angiotensin-converting enzyme inhibition and novel cardiovascular risk biomarkers: results from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors (TRAIN) study

BACKGROUND

Beneficial effects of angiotensin-converting enzyme (ACE) inhibitors seem to be mediated by mechanisms that are partly independent of blood pressure lowering. The present study evaluates effects of an ACE inhibitor (ie, fosinopril) intervention on novel cardiovascular risk factors.

METHODS

Data are from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors (TRAIN) study, a double-blind, crossover, randomized, placebo-controlled trial enrolling subjects > or =55 years old with high cardiovascular disease risk profile. Biomarkers of hemostasis (ie, plasminogen activator inhibitor 1, D-dimer), inflammation (ie, C-reactive protein, interleukin-6), and endothelial function (ie, endothelin 1, vascular cell adhesion molecule 1) were measured at the baseline, at the midterm, and at end of follow-up (after 1 year) clinic visits. Paired t test analyses (after Sidak's adjustment, P < .009) were performed to compare biomarkers modifications after fosinopril/placebo interventions.

RESULTS

Mean age of the sample (n = 290, women 43.4%) was 66.0 years old. No significant differences were reported for C-reactive protein, interleukin 6, plasminogen activator inhibitor 1, vascular cell adhesion molecule 1, and endothelin 1 levels in the comparisons between fosinopril and placebo interventions. D-dimer was the only biomarker showing a significant difference between fosinopril intervention (median 0.32 microg/mL, interquartile range 0.22-0.52 microg/mL) and placebo (median 0.29 microg/mL, interquartile range 0.20-0.47 microg/mL, P = .007) when analyses were restricted to participants with higher compliance to treatment and receiving the maximum ACE inhibitor dosage.

CONCLUSIONS

Angiotensin-converting enzyme inhibition does not significantly modify major biomarkers of inflammation, hemostasis, and endothelial function. Further studies should confirm the possible effect of ACE inhibitors on the fibrinolysis pathway.

Multifunctional actions of approved and candidate stroke drugs

Ischemic stroke causes brain damage by multiple pathways. Previous stroke trials have demonstrated that drugs targeting one or only a few of these pathways fail to improve clinical outcome after stroke. Drugs with multimodal actions have been suggested to overcome this challenge. In this review, we describe the mechanisms of action of agents approved for secondary prevention of ischemic stroke, such as antiplatelet, antihypertensive, and lipid-lowering drugs. These drugs exhibit considerable properties beyond their classical mechanisms, including neuroprotective and neuroregenerative properties. In addition, candidate stroke drugs currently studied in clinical phase III trials are described. Among these, albumin, hematopoietic growth factors, and citicoline have been identified as promising agents with multiple mechanisms. These drugs offer hope that additional treatment options for the acute phase after a stroke will become available in the near future.

Association of aortic valve sclerosis with thrombin generation in hypertensive patients

Aortic valve sclerosis (AVS) may predispose to a prothrombotic state, as AVS is predictor of cardiovascular events in hypertensive populations. Thrombin exerts non-thrombotic effects such as vessel tone regulation, progression of atherosclerosis and stimulation of atrial natriuretic peptide (ANP) secretion. We hypothesized that hypertensive patients with AVS may have a persistently activated thrombin generation. We studied 234 asymptomatic never-treated hypertensive patients (73 of them with AVS). Prothrombin F1+2 (F1+2), as a marker of thrombin generation and fibrin D-dimer, as a marker of thrombus formation, ANP and brain natriuretic peptide (BNP) were measured. Presence of AVS, aortic jet velocity and left ventricular diameter at diastole were determined by echocardiography. Glomerular filtration rate was estimated using the Modification of Diet in Renal Disease formula. F1+2 (median and interquartile range (IQR) = 1.05, 0.87-1.38 nM vs. 0.93, 0.72-1.16) and ANP (22, 14-37 pg ml(-1) vs. 17, 11-25) levels were greater, and glomerular filtration rate values (65+/-9 ml min(-1)/1.73 m2 vs. 68+/-11) were lower in hypertensive patients with AVS than in those without AVS. F1+2 (odds ratio, 95% CI = 2.94, 1.07-8.6) was independently associated with AVS after being adjusted for age, gender and the variables of cardiorenal functions measured. After 6 months of treatment using valsartan, F1+2 levels remained elevated in hypertensive patients with AVS (1.14, 0.83-1.42 nM vs. 1.07, 0.84-1.5, n=19), but decreased in those without AVS (1.01, 0.85-1.31 vs. 0.8, 0.84-1.78, n=27). Thrombin generation was associated with AVS in untreated hypertensive patients, and this association was persistent after blood-pressure-lowering treatment using valsartan.

Vascular benefits of angiotensin receptor blockers

There is convincing evidence that angiotensin II, through activation of the angiotensin II type 1 (AT1) receptor, is involved in the atherosclerotic process. Similarly, angiotensin receptor blockers decrease vascular inflammation, hypertrophy and thrombosis, which are the key components of the progression of atherosclerosis. In addition, in several animal models, angiotensin receptor blockade was able to inhibit atherosclerosis. However, the effects of angiotensin receptor blockers on clinical outcome in cardiovascular patients remains to be established. Contradictory results have been found on the reduction of the risk on myocardial infarctions and in-stent restenosis, although there is solid evidence for cerebroprotective effects of these receptor blockers. These differences may be related to the role of the AT2 receptor. This review discusses the role of angiotensin II and angiotensin receptor blockers in the atherosclerotic process and its translation into clinical practice.

Targeting mechanisms of hypertensive vascular disease with dual calcium channel and renin-angiotensin system blockade

Patients with hypertension, particularly those with diabetes mellitus, are at heightened risk for cardiovascular and renal disease. Accumulated evidence indicates that the majority of hypertensive patients at high risk will require more than one antihypertensive agent to reach their blood pressure (BP) target. A reasonable strategy is to use agents with complementary mechanisms of action to enhance BP-lowering efficacy and prevent target organ damage. In experimental models, the combination of a calcium channel blocker (CCB) with an agent that blocks the renin-angiotensin system (RAS), an angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker, improves measures of endothelial function, inflammation, ventricular remodelling and renal function to a greater degree than these classes given as monotherapy. In clinical trials, calcium channel/RAS blockade combination therapy has been shown to provide greater BP reductions and improve renal function in patients with diabetic and nondiabetic renal disease earlier and to a greater extent than monotherapy. In addition, dual calcium channel/RAS blockade increases arterial compliance, arterial distensibility and flow-mediated vasodilation. Expanding upon extensive research on the benefits of calcium channel blockade and RAS blockade for the prevention of vascular events and preclinical and clinical trial evidence suggests added effects of combination therapy by targeting the underlying mechanisms of hypertensive vascular disease.

Study of potential systemic oxidative stress animal models for the evaluation of antioxidant activity: status of lipid peroxidation and fat-soluble antioxidants

Although many compounds have already been tested in-vitro to determine their antioxidant profile, it is necessary to investigate the in-vivo effect of potential antioxidants. However, representative models of systemic oxidative stress have been poorly studied. Here, different potential systemic oxidative stress animal models have been investigated. These included a vitamin E-deficient rat, a diabetic rat and an atherosclerotic rabbit model. Plasma/serum malondialdehyde was measured as a parameter of oxidative damage. Plasma/serum fat-soluble antioxidants were determined as markers of antioxidant defence. We demonstrated that vitamin E-deficient rats were not suitable as a model of systemic oxidative stress, whereas diabetic and atherosclerotic animals showed increased systemic oxidative damage, as reflected by significantly augmented plasma/serum malondialdehyde. Moreover, plasma coenzyme Q9 increased by 80% in diabetic rats, confirming systemic oxidative stress. In view of these observations and economically favouring factors, the diabetic rat appeared to be the most appropriate systemic oxidative stress model. These findings have provided important information concerning systemic oxidative stress animal models for the in-vivo study of antioxidants.

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.

Direct regulation of insulin secretion by angiotensin II in human islets of Langerhans

AIMS/HYPOTHESIS

This study aimed to identify the expression of angiotensin II receptors in isolated human islets and beta cells and to examine the functional consequences of their activation.

MATERIALS AND METHODS

Single-cell RT-PCR was used to identify whether human islet cells express mRNA for type 1 angiotensin II receptors (AT(1)), and western blotting was used to determine AT(1) protein expression by human islets and MIN6 beta cells. We measured changes in intracellular calcium by microfluorimetry using Fura 2-loaded MIN6 cells and human islet cells. Dynamic insulin secretory responses were determined by RIA following perifusion of human islets and MIN6 cells.

RESULTS

Human islets expressed mRNAs for both the angiotensin precursor, angiotensinogen, and for angiotensin-converting enzyme. In addition, human and mouse beta cells expressed AT(1). These were functionally coupled to increases in intracellular calcium, which occurred at least in part through phospholipase-C-sensitive mechanisms and calcium influx through voltage-operated calcium channels. Short-term exposure of human islets and MIN6 cells to angiotensin II caused a rapid, short-lived initiation of insulin secretion at 2 mmol/l glucose and potentiation of insulin secretion induced by glucose (at 8 and 16.7 mmol/l).

CONCLUSIONS/INTERPRETATION

These data demonstrate that the AT(1) is expressed by beta cells and that angiotensin II effects a short-lived and direct stimulation of human and mouse beta cells to promote insulin secretion, most probably through elevations in intracellular calcium. Locally produced angiotensin II may be important in regulating a coordinated insulin secretory response from beta cells.

Effect of antihypertensive treatment on plasma fibrinogen and serum HDL levels in patients with essential hypertension

The influence of hypertension, and its treatment, on circulating lipid and fibrinogen (Fib) concentrations in patients with essential hypertension was investigated. The lipid profile and Fib levels were measured in 353 patients (131 men) with essential hypertension. Their median age was 60 years (range: 18-85 years). All patients had normal results from liver, renal, and thyroid function tests. There were 162 patients (45.9%) who were not receiving antihypertensive treatment. Of the remaining patients, 117 were taking 'lipid-hostile' beta-blockers, thiazide diuretics) antihypertensives and 74 were taking 'lipid-neutral' (angiotensin-converting enzyme inhibitors, calcium channel blockers, angiotensin-II receptor blockers) agents. Patients who were taking 'lipid-hostile' antihypertensive drugs had significantly higher plasma Fib concentrations when compared with those taking 'lipid-neutral' antihypertensives or those not receiving antihypertensive treatment. These differences were not attributable to established factors that influence plasma Fib levels, since when smokers and patients with diabetes mellitus and/or vascular disease were excluded, the difference remained significant. In addition, in these more homogeneous groups, patients receiving 'lipid-neutral' treatment had significantly higher serum high-density lipoprotein (HDL) cholesterol levels when compared with both those taking 'lipid-hostile' antihypertensives and untreated ones. There were no significant differences in the other lipid variables, independently of the presence/absence or the type of antihypertensives. These results suggest that antihypertensive drugs have additional effects, beyond lowering blood pressure, on other vascular risk factors, like Fib and HDL. These effects may depend on the type of drug used.

Sesamol regulates plasminogen activator gene expression in cultured endothelial cells: a potential effect on the fibrinolytic system

Sesamol is a component in the nutritional makeup of sesame that was identified as an antioxidant. In recent years, the importance of the plasminogen activator (PA) and its adjustment factor, plasminogen activator inhibitor-1 (PAI-1), in the prevention of atherosclerosis has gradually received recognition. The objective of this in vitro study was to demonstrate the effects of sesamol on PA and PAI-1. We also compared the effects of sesamol with two well-known antioxidants, vitamins C and E, by using human umbilical vein endothelial cells as an experimental model and by treating them with the above-mentioned three nutrients with doses up to 100 micromol/L. After 24 h, cells and cultural medium were collected for analysis. The concentrations of tissue PA (tPA), urokinase PA (uPA) and PAI-1 were measured by an enzymatic immunity method. Northern blot method was used to analyze the expression of mRNA of these three types of proteins. The results showed that sesamol increased the production of uPA and tPA significantly and also up-regulated the mRNA expressions of these proteins. On the other hand, vitamins C and E could induce tPA but not uPA. As for PAI-1, none of the nutrients induced any evident response. These findings suggest that the overall vascular fibrinolytic capacity may be enhanced by using sesamol to regulate PA gene expression.

Efficacy and tolerability of combination therapy with valsartan plus hydrochlorothiazide compared with amlodipine monotherapy in hypertensive patients with other cardiovascular risk factors: The VAST study

BACKGROUND

Recent antihypertensive treatment guidelines recommend greater use of combination therapies.

OBJECTIVES

The primary objective of this study was to determine whether combination therapy with valsartan 160 mg plus hydrochlorothiazide (HCTZ) 25 mg OD would be more effective than monotherapy with amlodipine 10 mg OD in reducing systolic blood pressure (SBP) in patients with moderate (stage II) hypertension and > or =1 other cardiovascular risk factor or concomitant condition. A secondary objective was to assess the effects of the study treatments on circulating markers of endothelial dysfunction and vascular inflammation.

METHODS

This was a multicenter, randomized, double-blind, active-controlled, 24-week study. After a 2-week, single-blind, placebo run-in period, patients were randomized to 3 groups, 2 of them receiving valsartan 160 mg OD and 1 receiving amlodipine 5 mg OD. At week 4, HCTZ 12.5 mg OD was added to valsartan in one of the treatment groups (V+HCTZ12.5), HCTZ 25 mg OD was added to the other (V+HCTZ25), and the amlodipine dose was force-titrated to 10 mg OD (A10). The primary efficacy variable was change in mean sitting SBP at week 24. Other variables were changes in mean sitting diastolic blood pressure (DBP) and mean pulse pressure (PP) from baseline, and response rate (systolic response defined as mean sitting SBP <140 mm Hg or a reduction in mean sitting SBP of > or =20 mm Hg from baseline; diastolic response defined as mean sitting DBP <90 mm Hg or a reduction in mean sitting DBP of > or =10 mm Hg from baseline). Changes in the following markers of endothelial dysfunction were determined at baseline and weeks 4, 12, and 24 in all randomized patients from the participating European and South African centers: high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), vascular tissue plasminogen activator (t-PA) antigen, and oxidized low-density lipoprotein (LDL).

RESULTS

The study enrolled 1088 patients with moderate hypertension (mean age, 61 years; 82% white; 53% women). The intent-to-treat population consisted of 1079 patients: 357 in the V+HCTZ12.5 group, 363 in the V+HCTZ25 group, and 359 in the A10 group. At baseline, the groups were comparable in terms of blood pressure and most other characteristics; the only statistically significant difference between groups was in the proportion of patients aged > or =65 years, which was lower in the amlodipine group (P = 0.01). At the end of the study, the least squares mean (SD) changes from baseline in mean sitting SBP were 27.1 (13.7), 29.7 (13.7), and 27.6 (13.8) mm Hg in the V+HCTZ12.5, V+HCTZ25, and A10 groups, respectively, with corresponding percent changes of 16%, 18%, and 17% (P < 0.05, V+HCTZ25 vs A10). The changes in mean sitting DBP did not differ significantly between groups. The reductions in PP were 17.5 (11.3), 18.7 (11.3), and 16.9 (11.3) mm Hg, with percent changes of 24%, 26%, and 23% (P < 0.05, V+HCTZ25 vs A10). Significant reductions in t-PA antigen were observed in both combination-therapy groups compared with the amlodipine monotherapy group at week 12 (P < 0.05); the reductions remained significant through the end of the study in the V+HCTZ12.5 group. There was a significant reduction in IL-6 and hs-CRP at week 12 with V+HCTZ25 compared with A10 (P < 0.05). Oxidized LDL values were reduced by approximately 10% with all treatments. Rates of total adverse events were significantly lower with the valsartan-based treatments compared with amlodipine monotherapy (49.7%, 49.6%, and 67.5% with V+HCTZ12.5, V+HCTZ25, and A10, respectively; P < 0.05). Rates of total discontinuations were a respective 10.1%, 9.0%, and 24.5%, and discontinuation rates due to AEs were 4.2%, 3.5%, and 18.2%. Leg edema was more common with amlodipine monotherapy than with the valsartan-based combinations (P < 0.05).

CONCLUSION

In this group of patients with moderate hypertension and > or =1 other cardiovascular risk factor or concomitant condition, similar and greater antihypertensive effects were seen with the fixed-dose combinations of valsartan 160 mg and HCTZ 12.5 and 25 mg OD, respectively, compared with amlodipine 10 mg OD, with significantly lower rates of treatment-related adverse events and possible beneficial effects on vascular markers.

The angiotensin II type 1 receptor blocker valsartan attenuates graft vasculopathy

OBJECTIVE

Transplant arteriosclerosis remains the major cause of graft failure after cardiac transplantation. Here, we investigated the effects of the angiotensin II type 1 receptor blocker valsartan on the development of transplant arteriosclerosis in a murine model of cardiac transplantation.

METHODS

Hearts from DBA/2 (H-2(d)) mice were heterotopically transplanted into B10.D2 (H-2(d)) mice. Recipients were treated with oral administration of valsartan (10 mg/kg/day) or vehicle.

RESULTS

Morphometrical analysis of the cardiac allografts harvested at 30 days revealed that valsartan significantly reduced the development of coronary atherosclerosis (intima/media ratio: 0.39 +/- 0.05 vs. 0.66 +/- 0.08, P < 0.01). At two weeks after transplantation, there was no significant difference between the two groups in expression of adhesion molecules and cytokines. Valsartan significantly reduced the number of peripheral mononuclear cells that differentiated into smooth muscle-like cells in the presence of basic fibroblast growth factor and platelet-derived growth factor BB (18.0 +/- 1.5 vs. 30.3 +/- 4.4 cells/HPF, P = 0.01).

CONCLUSIONS

These results suggest that angiotensin II plays a role in the pathogenesis of transplant arteriosclerosis and that blockade of angiotensin II type 1 receptor might be effective as a prophylactic therapy for transplant arteriosclerosis along with conventional immunosuppressive drugs.

Cholesterol diet enhances daily rhythm of Pai-1 mRNA in the mouse liver

Myocardial infarction frequently occurs in the morning, a phenomenon in part resulting from the downregulation of fibrinolytic activity. Plasminogen activator inhibitor-1 (PAI-1) is a key factor behind fibrinolytic activity, and its gene expression is controlled under the circadian clock gene in the mouse heart and liver. Hypercholesterolemia has been associated with impaired fibrinolysis due to enhanced PAI-1 activity, which has also been implicated in atherosclerosis. The aim of this study was to decipher whether the Pai-1 gene is still expressed daily with hypercholesterolemia. Hypercholesterolemia (1% cholesterol diet) did not significantly affect the daily expression of clock genes (Per2 and Bmal1) and clock-controlled genes (Dbp and E4bp4) in the liver (P > 0.05); however, daily expression of the Pai-1 gene and Pai-1 promoter regulating factor genes such as Nr4a1 was significantly upregulated (P < 0.01). Daily restricted feeding for 4 h during the day reset the gene expression of Per2, Pai-1, Nr4a1, and Tnf-alpha. Lesion of the suprachiasmatic nucleus, the location of the main clock system, led to loss of Per2 and Pai-1 daily expression profiles. In the present experiments, we demonstrated that hypercholesterolemia enhanced daily expression of the Pai-1, Tnf-alpha, and Nr4a1 genes in the mouse liver without affecting clock and clock-controlled genes. Therefore, the risk or high frequency of acute atherothrombotic events in the morning still seems to be a factor that may be augmented under conditions of hypercholesterolemia.

The ongoing telmisartan alone and in combination with ramipril global endpoint trial program

The renin-angiotensin system evolved to maintain volume homeostasis and blood pressure and to prevent ischemia during acute volume loss. But in the present age, these mechanisms are redundant, and the clinical significance of angiotensin II results from its pathologic effects, which are mediated by the angiotensin II type 1 (AT(1)) receptor. Activation of AT(1) receptors has been linked to pathologic processes that contribute to atherosclerosis and ischemic events, including oxidative stress, inflammatory processes, low-density lipoprotein cholesterol trafficking, and prothrombotic states. The Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) program will compare the efficacy of the angiotensin II receptor blocker (ARB) telmisartan, the angiotensin-converting enzyme (ACE) inhibitor ramipril, and combination therapy with telmisartan plus ramipril for reducing cardiovascular risk. The ARB telmisartan is distinguished by its long duration of action, which compares favorably with some other ARBs and conventional antihypertensives. Ramipril was shown in the Heart Outcomes Prevention Evaluation (HOPE) study to reduce the risk for myocardial infarction (MI) and other cardiovascular events in patients at high risk for cardiovascular events but without heart failure or a low ejection fraction. The ONTARGET program consists of 2 randomized, double-blind, multicenter international trials: a principal trial, ONTARGET, and a parallel trial, Telmisartan Randomized Assessment Study in ACE-I Intolerant Patients with Cardiovascular Disease (TRANSCEND). The treatment arms for the principal ONTARGET study are telmisartan 80 mg, ramipril 10 mg, and combination therapy with telmisartan 80 mg plus ramipril 10 mg; for the parallel study TRANSCEND, the treatment arms are telmisartan 80 mg and placebo. Both trials will assess cardiovascular outcomes in patients at high risk using the same criteria as that of the HOPE study, with a single exception: the TRANSCEND trial will enroll patients who do not tolerate ACE inhibitor treatment. The primary end points in both ONTARGET and TRANSCEND are death caused by cardiovascular disease, acute MI, stroke, and hospitalization because of congestive heart failure. The secondary end points include newly diagnosed heart failure, revascularization, new-onset type 2 diabetes mellitus, nephropathy, cognitive decrease and dementia, and newly diagnosed atrial fibrillation; these will be used for hypothesis generation.

Angiotensin II and nitric oxide interaction

Nitric oxide degradation linked to endothelial dysfunction plays a central role in cardiovascular diseases. Superoxide producing enzymes such as NADPH oxidase and xanthine oxidase are responsible for NO degradation as they generate a variety of reactive oxygen species (ROS). Moreover, superoxide is rapidly degraded by superoxide dismutase to produce hydrogen peroxide leading to the uncoupling of NO synthase and production of increased amount of superoxide. Angiotensin II is an important stimulus of NADPH oxidase. Through its AT(1) receptor, Ang II stimulates the long-term increase of several membrane component of NADPH oxidase such as P(22) phox or nox-1 and causes an increased activity of NADPH oxidase with inactivation of NO leading to impaired endothelium-dependent vasorelaxation, vascular smooth muscle cell hypertrophy, proliferation and migration, extracellular matrix formation, thrombosis, cellular infiltration and inflammatory reaction. Several preclinical and clinical studies have now confirmed the involvement of the AT(1) receptor in endothelial dysfunction. It is proposed that the AT(2) receptor counterbalances the deleterious effect of the Ang II-induced AT(1) receptor stimulation through bradykinin and NOS stimulation. This mechanism could be especially relevant in pathological cases when the NADPH oxidase activity is blocked with an AT(1) receptor antagonist.