Effects of olmesartan and enalapril at low or high doses on cardiac, renal and vascular interstitial matrix in spontaneously hypertensive rats

Changes in extracellular matrix in subcutaneous small resistance arteries of patients with essential hypertension

BACKGROUND

In the development of hypertensive microvascular remodeling, a relevant role may be played by changes in extracellular matrix proteins. Aim of this study was the to evaluate some extracellular matrix components within the tunica media of subcutaneous small arteries in 9 normotensive subjects and 12 essential hypertensive patients, submitted to a biopsy of subcutaneous fat from the gluteal or the anterior abdominal region.

PATIENTS AND METHODS

Subcutaneous small resistance arteries were dissected and mounted on an isometric myograph, and the tunica media to internal lumen ratio was measured. In addition, fibronectin, laminin, transforming growth factor-beta-1 (TGF-β1) and emilin-1 contents within the tunica media were evaluated by immunofluorescence and relative immunomorphometrical analysis (immunopositivity % of area). The total collagen content and collagen subtypes within the tunica media were evaluated using both Sirius red staining (under polarized light) and immunofluorescence assay.

RESULTS

Normotensive controls had less total and type III collagen in respect with hypertensive patients. Fibronectin and TGF-β1 tunica media content was significantly greater in essential hypertensive patients, compared with normotensive controls, while laminin and emilin-1 tunica media content was lesser in essential hypertensive patients, compared with normotensive controls. A significant correlation was observed between fibronectin tunica media content and media to lumen ratio.

CONCLUSIONS

Our results indicate that, in small resistance arteries of patients with essential hypertension, a relevant fibrosis may be detected; fibronectin and TGF-β1 tunica media content is increased, while laminin and emilin-1 content is decreased; these changes might be involved in the development of small resistance artery remodeling in humans.

Differential renal effects of candesartan at high and ultra-high doses in diabetic mice-potential role of the ACE2/AT2R/Mas axis

High doses of Ang II receptor (AT1R) blockers (ARBs) are renoprotective in diabetes. Underlying mechanisms remain unclear. We evaluated whether high/ultra-high doses of candesartan (ARB) up-regulate angiotensin-converting enzyme 2 (ACE2)/Ang II type 2 receptor (AT2R)/Mas receptor [protective axis of the of the renin–angiotensin system (RAS)] in diabetic mice. Systolic blood pressure (SBP), albuminuria and expression/activity of RAS components were assessed in diabetic db/db and control db/+ mice treated with increasing candesartan doses (intermediate, 1 mg/kg/d; high, 5 mg/kg/d; ultra-high, 25 and 75 mg/kg/d; 4 weeks). Lower doses candesartan did not influence SBP, but ultra-high doses reduced SBP in both groups. Plasma glucose and albuminuria were increased in db/db compared with db/+ mice. In diabetic mice treated with intermediate dose candesartan, renal tubular damage and albuminuria were ameliorated and expression of ACE2, AT2R and Mas and activity of ACE2 were increased, effects associated with reduced ERK1/2 phosphorylation, decreased fibrosis and renal protection. Ultra-high doses did not influence the ACE2/AT2R/Mas axis and promoted renal injury with increased renal ERK1/2 activation and exaggerated fibronectin expression in db/db mice. Our study demonstrates dose-related effects of candesartan in diabetic nephropathy: intermediate–high dose candesartan is renoprotective, whereas ultra-high dose candesartan induces renal damage. Molecular processes associated with these effects involve differential modulation of the ACE2/AT2R/Mas axis: intermediate–high dose candesartan up-regulating RAS protective components and attenuating pro-fibrotic processes, and ultra-high doses having opposite effects. These findings suggest novel mechanisms through the protective RAS axis, whereby candesartan may ameliorate diabetic nephropathy. Our findings also highlight potential injurious renal effects of ultra-high dose candesartan in diabetes.

Risk of hyperkalemia in patients with moderate chronic kidney disease initiating angiotensin converting enzyme inhibitors or angiotensin receptor blockers: a randomized study

Background

Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers are renoprotective but both may increase serum potassium concentrations in patients with chronic kidney disease (CKD). The proportion of affected patients, the optimum follow-up period and whether there are differences between drugs in the development of this complication remain to be ascertained.

Methods

In a randomized, double-blind, phase IV, controlled, crossover study we recruited 30 patients with stage 3 CKD under restrictive eligibility criteria and strict dietary control. With the exception of withdrawals, each patient was treated with olmesartan and enalapril separately for 3 months each, with a 1-week wash-out period between treatments. Patients were clinically assessed on 10 occasions via measurements of serum and urine samples. We used the Cochran–Mantel–Haenszel statistics for comparison of categorical data between groups. Comparisons were also made using independent two-sample t-tests and Welch’s t-test. Analysis of variance (ANOVA) was performed when necessary. We used either a Mann–Whitney or Kruskal-Wallis test if the distribution was not normal or the variance not homogeneous.

Results

Enalapril and olmesartan increased serum potassium levels similarly (0.3 mmol/L and 0.24 mmol/L respectively). The percentage of patients presenting hyperkalemia higher than 5 mmol/L did not differ between treatments: 37% for olmesartan and 40% for enalapril. The mean e-GFR ranged 46.3 to 48.59 ml/mint/1.73 m² in those treated with olmesartan and 46.8 to 48.3 ml/mint/1.73 m² in those with enalapril and remained unchanged at the end of the study. The decreases in microalbuminuria were also similar (23% in olmesartan and 29% in enalapril patients) in the 4 weeks time point. The percentage of patients presenting hyperkalemia, even after a two month period, did not differ between treatments. There were no appreciable changes in sodium and potassium urinary excretion.

Conclusions

Disturbances in potassium balance upon treatment with either olmesartan or enalapril are frequent and without differences between groups. The follow-up of these patients should include control of potassium levels, at least after the first week and the first and second month after initiating treatment.

Trial registration

The trial EudraCT “2008-002191-98”.

Reduction of Cardiovascular Risk through Angiotensin II Type 1 Receptor Antagonism : Focus on Olmesartan Medoxomil

It is well recognized that angiotensin II is involved in the pathogenesis of hypertension. Less well recognized - until recently, at least - is its involvement in the pathogenesis of atherosclerosis. However, it is now evident that angiotensin II promotes oxidative stress, vascular remodelling, inflammation, and the formation of atherosclerotic lesions. These actions, which are mediated almost exclusively by the angiotensin II type 1 (AT(1)) receptor, can be blocked by administration of angiotensin II type 1 receptor antagonists (angiotensin receptor blockers [ARBs]). Of the seven ARBs currently in clinical use, olmesartan is one of the most effective. The rapid and consistent antihypertensive efficacy of this drug, which allows a high proportion of patients to achieve their target blood pressure (BP), is associated with beneficial effects on oxidative stress, vascular remodelling, inflammation, and atherosclerotic lesion formation. These effects appear to be independent of the BP-lowering activity of olmesartan. In clinical trials, olmesartan has been shown to control microinflammation in hypertensive patients, to reduce oxidative stress in patients with type 2 diabetes mellitus, and to normalize the wall: lumen ratio of small resistance arteries (a measure of vascular remodelling) in patients with hypertension. Moreover, in a 2-year study involving hypertensive patients with carotid atherosclerosis (the MORE [Multicentre Olmesartan atherosclerosis Regression Evaluation] trial), olmesartan reduced the intima-media thickness of the carotid artery and significantly reduced the volume of large atherosclerotic plaques. These data suggest that olmesartan may reduce cardiovascular risk by simultaneously normalizing BP and reversing the proatherogenic effects of angiotensin II.

Lisinopril attenuates renal oxidative injury in L-NAME-induced hypertensive rats

Hypertension and related oxidative stress are involved in the pathogenesis of any renal diseases. Angiotensin-converting enzyme inhibitors have multi-directional renoprotective effects. In this study, we aimed to investigate whether lisinopril treatment has any biochemical alterations on renal tissue in L-NAME (Nε-nitro-L-arginine methyl ester) induced hypertension model. Twenty-eight Sprague-Dawley rats were included in this study and divided into four equal groups (n = 7): control group, L-NAME treated group (75 mg/kg/day), L-NAME plus lisinopril treated group and only lisinopril treated group (10 mg/kg/day). L-NAME and lisinopril were continued for 6 weeks. Systolic blood pressures were measured by using tail cuff method. In biochemical analysis, malondialdehyde (MDA, an index of lipid peroxidation) levels, the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in renal tissues were used as markers of oxidative stress-induced renal impairment. Microalbumin and N-acetyl-β-D-glucosaminidase (NAG) in urine were determined as markers of renal tubular damage related to hypertension. Chronic L-NAME administration resulted in a significant depletion of serum nitric oxide (NO). When compared with control group, serum creatinine, microalbumin, urine NAG, renal tissue MDA level, and CAT activities were significantly high, while renal tissue SOD and GSH-Px activities low in L-NAME group. In the L-NAME plus lisinopril treated group, serum creatinine, microalbumin and urine NAG, renal MDA level and CAT activity decreased, whereas SOD, GSH-Px activities in renal tissue and serum NO levels were increased. Thus, lisinopril treatment reversed these effects. There were not any significant difference between L-NAME plus lisinopril treated group and control group concerning serum creatinine, renal tissue MDA level and SOD, GSH-Px, CAT activities. These results suggest that lisinopril could diminish biochemical alterations in L: -NAME induced hypertensive renal damage that occurs by oxidative stress.

Efficacy of ACE inhibitors in chronic heart failure with preserved ejection fraction--a meta analysis of 7 prospective clinical studies

BACKGROUND

The effect of ACE inhibitors on the prognosis of chronic heart failure patients with preserved left ventricular ejection fraction remains controversial.

AIMS

To assess the impact of ACE inhibitors on the prognosis of chronic heart failure patients with preserved left ventricular ejection fraction.

METHODS AND RESULTS

Seven prospective studies evaluating the effect of ACE inhibitors compared to placebo or other classes of drugs, such as monotherapy or first-line therapy, on the prognosis of chronic heart failure patients with preserved left ventricular ejection fraction were included. A total of 2554 patients (mean age: 75.1 years, female: 58%) were recruited with an average follow up of 20.9 months. The primary etiology of heart failure with preserved ejection fraction was ischemic heart disease (33.7%), hypertension (69.1%) and diabetes mellitus (25.8%). Our results demonstrated that ACE inhibitors significantly reduced all-cause mortality (odds ratio, OR = 0.52; 95% Confidence Interval (CI), 0.41 to 0.64; P<0.01). Furthermore, ACE inhibitors were able to reduce heart failure related rehospitalization or treatment over 20.9 months (p<0.05) in a subgroup of patients aged over 75 years. However, death due to worsening of heart failure, heart failure related rehospitalization and any-cause readmission were not affected (OR = 0.88; 95% CI: 0.66 to 1.17; P = 0.37 for death due to worsening of heart failure; OR = 0.81; 95% CI: 0.63 to 1.05; P = 0.11 for heart failure related rehospitalization and OR = 0.88; 95% CI: 0.68 to 1.14; P = 0.33 for any-cause readmission, respectively).

CONCLUSIONS

In patients with chronic heart failure with preserved ejection fraction, ACE inhibitors reduced all-cause mortality without affecting mortality due to heart failure and any-cause rehospitalization.

Blockade of AT1 receptors protects the blood-brain barrier and improves cognition in Dahl salt-sensitive hypertensive rats

BACKGROUND

The present study tested the hypothesis that inappropriate activation of the brain renin-angiotensin system (RAS) contributes to the pathogenesis of blood-brain barrier (BBB) disruption and cognitive impairment during development of salt-dependent hypertension. Effects of an angiotensin II (AngII) type-1 receptor blocker (ARB), at a dose that did not reduce blood pressure, were also examined.

METHODS

Dahl salt-sensitive (DSS) rats at 6 weeks of age were assigned to three groups: low-salt diet (DSS/L; 0.3% NaCl), high-salt diet (DSS/H; 8% NaCl), and high-salt diet treated with ARB, olmesartan at 1 mg/kg.

RESULTS

DSS/H rats exhibited hypertension, leakage from brain microvessels in the hippocampus, and impaired cognitive functions, which were associated with increased brain AngII levels, as well as decreased mRNA levels of tight junctions (TJs) and collagen-IV in the hippocampus. In DSS/H rats, olmesartan treatment, at a dose that did not alter blood pressure, restored the cognitive decline, and ameliorated leakage from brain microvessels. Olmesartan also decreased brain AngII levels and restored mRNA expression of TJs and collagen-IV in DSS/H rats.

CONCLUSIONS

These results suggest that during development of salt-dependent hypertension, activation of the brain RAS contributes to BBB disruption and cognitive impairment. Treatment with an ARB could elicit neuroprotective effects in cognitive disorders by preventing BBB permeability, which is independent of blood pressure changes.

Regulatory function of a malleable protein matrix as a novel fermented whey product on features defining the metabolic syndrome

Previously, we reported that a malleable protein matrix (MPM), composed of whey fermented by a proprietary Lactobacillus kefiranofaciens strain, has immunomodulatory and anti-inflammatory properties. MPM consumption leads to a considerable reduction in the cytokine and chemokine production (tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6), thus lowering chronic inflammation or metaflammation. Inhibition of metaflammation should provide positive impact, particularly in the context of dyslipidemia, insulin resistance, and hypertension. In this study, we investigated whether short-term MPM supplementation ameliorates those features of metabolic syndrome (MetS). The ability of MPM to potentially regulate triglyceride level, cholesterol level, blood glucose level, and hypertension was evaluated in different animal models. MPM lowers triglyceride level by 37% (P < .05) in a poloxamer 407 dyslipidemia-induced rat model. It also reduces total cholesterol by 18% (P < .05) and low-density lipoprotein-cholesterol level by 32% (P < .05) and raises high-density lipoprotein-cholesterol level by 17% (P < .01) in Syrian Golden hamsters fed a high fat/high cholesterol diet for 2 weeks. MPM reestablishes the fasting glucose insulin ratio index to normal levels (P = .07) in this latter model and lowers the plasma glucose level area under the curve (-10%, P = .09) in fructose-fed rats after 2 weeks of treatment. In spontaneously hypertensive rats, MPM-treated animals showed a reduction of SBP by at least 13% (P < .05) for 4 weeks. Results from this study suggest that MPM is a functional ingredient with beneficial effects on lipid metabolism, blood glucose control, and hypertension that might contribute to the management of MetS and thus reducing the risk of cardiovascular diseases.

Effects of Melatonin and Pycnogenol on Small Artery Structure and Function in Spontaneously Hypertensive Rats

It was suggested that oxidative stress has a key role in the development of endothelial dysfunction, as well as microvascular structural alterations. Therefore, we have investigated 2 substances with antioxidant properties: melatonin and Pycnogenol. We treated 7 spontaneously hypertensive rats (SHRs) with melatonin and 7 with Pycnogenol for 6 weeks. We compared results obtained with those observed in 7 SHRs and 7 Wistar-Kyoto normotensive control rats kept untreated. Mesenteric small resistance arteries were dissected and mounted on a wire myograph, and a concentration-response curve to acetylcholine was performed. Aortic contents of metalloproteinase 2, Bax, inducible NO synthase, and cyclooxygenase 2 were evaluated, together with the aortic content of total collagen and collagen subtypes and apoptosis rate. A small reduction in systolic blood pressure was observed. A significant improvement in mesenteric small resistance artery structure and endothelial function was observed in rats treated with Pycnogenol and melatonin. Total aortic collagen content was significantly greater in untreated SHRs compared with Wistar-Kyoto control rats, whereas a full normalization was observed in treated rats. Apoptosis rate was increased in the aortas of untreated SHRs compared with Wistar-Kyoto control rats; an even more pronounced increase was observed in treated rats. Bax and metalloproteinase 2 expressions changed accordingly. Cyclooxygenase 2 and inducible NO synthase were more expressed in the aortas of untreated SHRs compared with Wistar-Kyoto control rats; this pattern was normalized by both treatments. In conclusion, our data suggest that treatment with Pycnogenol and melatonin may protect the vasculature, partly independent of blood pressure reduction, probably through their antioxidant effects.

Use of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker therapy to reduce cardiovascular events in high-risk patients: part 2

As presented previously in Part 1 of this 2-part article, many long-term clinical trials provide overwhelming evidence of the benefits of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) across the cardiovascular continuum. Trials also indicate additive or synergistic effects of combination therapy in renal disease and heart failure. Part 2, which is presented here, discusses the extensive interaction of the renin-angiotensin system (RAS) with the cellular and molecular pathophysiology of cardiovascular disease and the cross-continuum effects of ARBs and ACE inhibitors, which raises the possibility that RAS inhibition can offer protection in high-risk patients who do not have symptoms. Although trial evidence supports the effectiveness of monotherapy, the benefits of combined ACE inhibitor/ARB therapy in high-risk patients await confirmation. Ongoing clinical research will provide new and important information regarding the efficacy of specific combination (ACE inhibitor/ARB) therapies.

Effect of angiotensin receptor blockade on endothelial function: focus on olmesartan medoxomil

Endothelial dysfunction is the common link between cardiovascular disease risk factors and the earliest event in the cascade of incidents that results in target organ damage. Angiotensin II, the terminal pressor effector arm of the renin-angiotensin-aldosterone system, increases blood pressure (BP) by vasoconstriction and sodium and fluid retention, and has a pro-oxidative action that induces endothelial dysfunction and contributes to vascular remodeling. Angiotensin receptor blockers (ARBs) reduce BP and morbidity and mortality in patients with hypertension, ventricular hypertrophy, diabetes mellitus, and renal disease. Olmesartan medoxomil is a long-acting, well-tolerated, effective ARB that prevents or reverses endothelial dysfunction in animal models of atherosclerosis, hypertension, diabetes, nephropathy, and retinopathy. Olmesartan medoxomil, a prodrug of olmesartan approved for the treatment of hypertension, has been shown to ameliorate endothelial dysfunction in patients with hypertension or diabetes. In randomized studies, the drug reduces vascular inflammation and the volume of large atherosclerotic plaques, increases the number of regenerative endothelial progenitor cells in the peripheral circulation, improves endothelium-dependent relaxation, and restores the normal resistance vessel morphology. Importantly, the impact of olmesartan medoxomil on endothelial dysfunction is thought to be independent of BP lowering.

Olmesartan medoxomil: a review of its use in the management of hypertension

Olmesartan medoxomil (Olmetec, Benicar) is an angiotensin II type 1 (AT(1)) receptor antagonist (angiotensin receptor blocker [ARB]) that inhibits the actions of angiotensin II on the renin-angiotensin-aldosterone system, which plays a key role in the pathogenesis of hypertension. Oral olmesartan medoxomil 10-40 mg once daily is recommended for the treatment of adult patients with hypertension. In those with inadequate BP control using monotherapy, fixed-dose olmesartan medoxomil/hydrochlorothiazide (HCTZ) [Olmetec plus, Benicar-HCT] combination therapy may be initiated. Extensive clinical evidence from several large well designed trials and the clinical practice setting has confirmed the antihypertensive efficacy and good tolerability profile of oral olmesartan medoxomil, as monotherapy or in combination with HCTZ, in patients with hypertension, including elderly patients with isolated systolic hypertension (ISH). Notably, BP control is sustained throughout the 24-hour dosage interval, including during the last 4 hours of this period. In clinical trials, olmesartan medoxomil monotherapy provided better antihypertensive efficacy than losartan, candesartan cilexetil or irbesartan monotherapy, and was at least as effective as valsartan treatment, with a faster onset of action than other ARBs in terms of reductions from baseline in diastolic BP (DBP) and, in most instances, systolic BP (SBP). Combination therapy with olmesartan medoxomil plus HCTZ was superior to that with benazepril plus amlodipine, as effective as that with losartan plus HCTZ, noninferior to that with atenolol plus HCTZ, but less effective than that with telmisartan plus HCTZ, in individual trials. Data from ongoing clinical outcome trials are required to more fully determine the relative position of olmesartan medoxomil therapy in the management of hypertension. In the meantime, the consistent antihypertensive efficacy during the entire 24-hour dosage interval and good tolerability profile of olmesartan medoxomil, with or without HCTZ, make it a valuable option for the treatment of adult patients with hypertension, including the elderly.

Supratherapeutic doses of angiotensin receptor blockers to decrease proteinuria in patients with chronic kidney disease

An important endpoint in treating chronic kidney disease, a prevalent disease that can lead to kidney failure and cardiovascular disease, is reducing proteinuria. Proteinuria is an independent risk factor for disease progression and the development of cardiovascular disease and is a key factor that can be used to guide therapy designed to maximize kidney protection. Proteinuria is targeted by using pharmacologic agents that suppress the renin-angiotensin-aldosterone system (RAAS), a regulator of intravascular volume and blood pressure; this has been shown to decrease proteinuria, slow disease progression, and improve coronary disease outcome, independent of effects on blood pressure. The efficacy of RAAS blockers, including angiotensin receptor blockers and angiotensin-converting enzyme inhibitors, may be limited by currently recommended doses, which are based on treatment of hypertension. Data are now emerging from clinical trials demonstrating that use of 'supratherapeutic doses' (doses greater than those approved for lowering blood pressure), compared with standard doses, has favorable safety, tolerability, and efficacy in reducing proteinuria in both diabetic and nondiabetic patients with chronic kidney disease. Supratherapeutic dosing may be a valuable approach for optimizing RAAS blockade and providing renoprotection.

Atherosclerosis and the protective role played by different proteins in apolipoprotein E-deficient mice

The aim of the present study was to analyze the early events in atherogenesis and the role of pro- or anti-atherosclerotic proteins in the development of atherosclerotic lesions. We used apolipoprotein E-deficient (E(0)) mice that spontaneously develop hypercholesterolemia and atherosclerotic lesions in the aorta in a time-dependent manner. Aortas of mice aged 6, 8, 10 and 12 weeks were examined to determine histopathological changes. In mice aged 8-12 weeks, developing atherosclerotic lesions were present in different regions of the aortas. These lesions protruded into the lumen of the vessel and showed lipid deposits, lipid-filled macrophages and extensive accumulation of collagen and elastic fibers throughout the entire arterial wall. A parallel immunohistochemical study included analysis of three proteins known to be involved in atherosclerosis, i.e. inducible nitric oxide synthase (iNOS, NOS2), vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 (MMP2). Increased immunolabelling of iNOS and VEGF accompanied atherosclerosis development in E(0) mice aged 8, 10 and 12 weeks. On the contrary, immunolabelling for MMP2 was negative in E(0) mice aged 10 and 12 weeks. Our results indicate morphological alterations in the Tunica intima and Tunica media of atherosclerotic aortas and possible protective roles for iNOS and VEGF proteins against atherosclerosis development. These data may be relevant for developing therapeutic strategies for atherosclerosis development.

Long-term, high-dosage candesartan suppresses inflammation and injury in chronic kidney disease: nonhemodynamic renal protection

Recent evidence suggests that higher-than-usual antihypertensive dosages of renin-angiotensin-aldosterone system blockers may provide additional protection from progression of chronic renal disease; however, there have been few long-term studies, and the underlying mechanisms remain uncertain. This study examined the effects of long-term (14 mo) administration of ultrahigh dosages of the angiotensin receptor blocker candesartan on the progression of renal injury in spontaneously hypertensive rats (SHR). Beginning 8 wk after birth, SHR underwent unilateral nephrectomy and were given vehicle (control), or candesartan at a standard 5 mg/kg per d (T5), high 25 mg/kg per d (T25), or ultrahigh 75 mg/kg per d dosage (T75). After 2 wk, BP was reduced in all treated groups; however, it was better controlled in the high-dosage groups (T25 and T75). Urinary protein was significantly reduced in T75 after 2 wk of treatment and was also declined in the other two treatment groups but only after 2 mo. Exogenous angiotensin II test showed that complete angiotensin receptor blockade was achieved only in the high-dosage groups. Renal inflammation and macrophage (ED-1) infiltration were significantly ameliorated in both T25 and T75 but not in T5 rats. This was associated with the changes of tubular expression of monocyte chemoattractant protein-1, RANTES (regulated upon expression normal T cell expressed and secreted), and the phosphorylated NF-kappaB, a marker for activation. Suppression of ED-1, monocyte chemoattractant protein-1, and RANTES expression and NF-kappaB activation were greater in T75 as compared with T25. These findings suggest that candesartan has dosage-dependent, anti-inflammatory effects that are mediated by suppression of NF-kappaB activation and chemokine expression. Renal protection with high-dosage therapy may depend on these nonhemodynamic effects.