Reinventing the ACE inhibitors: some old and new implications of ACE inhibition

Mortality among patients due to adverse drug reactions that lead to hospitalization: a meta-analysis

PURPOSE

The aim of this study was to estimate the prevalence of mortality among patients due to adverse drug reactions that lead to hospitalisation (fatal ADR_Ad), to explore the heterogeneity in its estimation through subgroup analysis of study characteristics, and to identify system-organ classes involved and causative drugs for fatal ADR_Ad.

METHODS

We identified prospective ADR_Ad-related studies via screening of the PubMed and Google Scholar databases with appropriate key terms. We estimated the prevalence of fatal ADR_Ad using a double arcsine method and explored heterogeneity using the following study characteristics: age groups, wards, study region, ADR definitions, ADR identification methods, study duration and sample size. We examined patterns of fatal ADR_Ad and causative drugs.

RESULTS

Among 312 full-text articles assessed, 49 studies satisfied the selection criteria and were included in the analysis. The mean prevalence of fatal ADR_Ad was 0.20% (95% CI: 0.13-0.27%; I² = 93%). The age groups and study wards were the important heterogeneity modifiers. The mean fatal ADR_Ad prevalence varied from 0.01% in paediatric patients to 0.44% in the elderly. Subgroup analysis showed a higher prevalence of fatal ADR_Ad in intensive care units, emergency departments, multispecialty wards and whole hospitals. Computer-based monitoring systems in combination with other methods detected higher mortality. Intracranial haemorrhage, renal failure and gastrointestinal bleeding accounted for more than 50% of fatal ADR_Adcases. Warfarin, aspirin, renin-angiotensin system (RAS) inhibitors and digoxin accounted for 60% of fatal ADR_Ad.

CONCLUSIONS

ADR_Ad is an important cause of mortality. Strategies targeting the safer use of warfarin, aspirin, RAS inhibitors and digoxin could reduce the large number of fatal ADR_Adcases.

New Quantitative Structure-Activity Relationship Model for Angiotensin-Converting Enzyme Inhibitory Dipeptides Based on Integrated Descriptors

Angiotensin-converting enzyme (ACE) inhibitory peptides derived from food proteins have been widely reported for hypertension treatment. In this paper, a benchmark data set containing 141 unique ACE inhibitory dipeptides was constructed through database mining, and a quantitative structure-activity relationships (QSAR) study was carried out to predict half-inhibitory concentration (IC₅₀) of ACE activity. Sixteen descriptors were tested and the model generated by G-scale descriptor showed the best predictive performance with the coefficient of determination (R²) and cross-validated R² (Q²) of 0.6692 and 0.6220, respectively. For most other descriptors, R² were ranging from 0.52 to 0.68 and Q² were ranging from 0.48 to 0.61. A complex model combining all 16 descriptors was carried out and variable selection was performed in order to further improve the prediction performance. The quality of model using integrated descriptors (R² 0.7340 ± 0.0038, Q² 0.7151 ± 0.0019) was better than that of G-scale. An in-depth study of variable importance showed that the most correlated properties to ACE inhibitory activity were hydrophobicity, steric, and electronic properties and C-terminal amino acids contribute more than N-terminal amino acids. Five novel predicted ACE-inhibitory peptides were synthesized, and their IC₅₀ values were validated through in vitro experiments. The results indicated that the constructed model could give a reliable prediction of ACE-inhibitory activity of peptides, and it may be useful in the design of novel ACE-inhibitory peptides.

Relationship of quadriceps muscle power and optimal shortening velocity with angiotensin-converting enzyme activity in older women

BACKGROUND

The goal of this study was to assess whether angiotensin-converting enzyme (ACE) activity is related to muscle function (strength, power and velocity), as well as to assess if ACE inhibitors (ACEIs) and other angiotensin system blocking medications (ASBMs) influence muscle performance in elderly women.

SUBJECTS AND METHODS

Ninety-five community-dwelling elderly women took part in this study. Anthropometric data, blood ACE activity analysis, maximum power (Pmax) and optimal shortening velocity (υopt) of the knee extensor muscles, handgrip strength, physical activity (PA) and functional performance were measured.

RESULTS

Women taking ACEI were on average almost 2 years older than the women who did not take ACEI. They took more medicines and were also characterized by significantly lower level of ACE, but they did not differ in terms of PA level, results of functional performance and parameters characterizing muscle functions. No correlations of ACE activity with Pmax and handgrip strength, as well as with PA or functional performance were found. Higher ACE activity was connected with lower υopt for women who did not take any ASBMs (rho =-0.37; p=0.01).

CONCLUSION

Serum ACE activity was not associated with muscle strength, power and functional performance in both ASBM users and nonusers, but was associated with optimal shortening velocity of quadriceps muscles in older women. Further prospective studies are needed to assess if ACEIs or other ASBMs may slow down the decline in muscle function and performance.

Perindopril Induces TSP-1 Expression in Hypertensive Patients with Endothelial Dysfunction in Chronic Treatment

Thrombospondin-1 (TSP-1) is a potent endogenous inhibitor of both physiological and pathological angiogenesis, widely studied as a target in drug development for treating cancer. Several studies performed in the cardiovascular field on TSP-1 are contradictory, the role of TSP-1 in the physiopathology of cardiovascular disorders (CVDs) being, for the moment, incompletely understood and may be due to the presence of several domains in its structure which can stimulate many cellular receptors. It has been reported to inhibit NO-mediated signaling and to act on the angiogenesis, tissue perfusion, endothelial cell proliferation, and homeostasis, so we aimed to quantify the effect Perindopril has on TSP-1 plasma levels in hypertensive patients with endothelial dysfunction in comparison with other antihypertensive drugs, such as beta blockers, calcium channel blockers, and diuretics, in a chronic treatment. As a conclusion, patients under treatment with Perindopril had increased plasma levels of TSP-1 compared with other hypertensive patients and with the control group. The results of this study confirms the pleiotropic properties of Perindopril: anti-proliferative, anti-inflammatory, with effects showed by quantifying a single biomarker: TSP-1.

Comparative Solid-State Stability of Perindopril Active Substance vs. Pharmaceutical Formulation

This paper presents the results obtained after studying the thermal stability and decomposition kinetics of perindopril erbumine as a pure active pharmaceutical ingredient as well as a solid pharmaceutical formulation containing the same active pharmaceutical ingredient (API). Since no data were found in the literature regarding the spectroscopic description, thermal behavior, or decomposition kinetics of perindopril, our goal was the evaluation of the compatibility of this antihypertensive agent with the excipients in the tablet under ambient conditions and to study the effect of thermal treatment on the stability of perindopril erbumine. ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared) spectroscopy, thermal analysis (thermogravimetric mass curve (TG-thermogravimetry), derivative thermogravimetric mass curve (DTG), and heat flow (HF)) and model-free kinetics were chosen as investigational tools. Since thermal behavior is a simplistic approach in evaluating the thermal stability of pharmaceuticals, in-depth kinetic studies were carried out by classical kinetic methods (Kissinger and ASTM E698) and later with the isoconversional methods of Friedman, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa. It was shown that the main thermal degradation step of perindopril erbumine is characterized by activation energy between 59 and 69 kJ/mol (depending on the method used), while for the tablet, the values were around 170 kJ/mol. The used excipients (anhydrous colloidal silica, microcrystalline cellulose, lactose, and magnesium stearate) should be used in newly-developed generic solid pharmaceutical formulations, since they contribute to an increased thermal stability of perindopril erbumine.

Cardiac remodeling following reperfused acute myocardial infarction is linked to the concomitant evolution of vascular function as assessed by cardiovascular magnetic resonance

BACKGROUND

Left ventricular (LV) remodeling following acute myocardial infarction (MI) is difficult to predict at an individual level although a possible interfering role of vascular function has yet to be considered to date. This study aimed to determine the extent to which this LV remodeling is influenced by the concomitant evolution of vascular function and LV loading conditions, as assessed by phase-contrast Cardiovascular Magnetic Resonance (CMR) of the ascending aorta.

METHODS

CMR was performed in 121 patients, 2-4 days after reperfusion of a first ST-segment elevation myocardial infarction and 6 months thereafter. LV remodeling was: (i) assessed by the 6-month increase in end-diastolic volume (EDV) and/or ejection fraction (EF) and (ii) correlated with the indexed aortic stroke volume (mL.m-2), determined by a CMR phase-contrast sequence, along with derived functional vascular parameters (total peripheral vascular resistance (TPVR), total arterial compliance index, effective arterial elastance).

RESULTS

At 6 months, most patients were under angiotensin enzyme converting inhibitors (86%) and beta-blockers (84%) and, on average, all functional vascular parameters were improved whereas blood pressure levels were not. An increase in EDV only (EDV+/EF-) was documented in 17% of patients at 6 months, in EF only (EDV-/EF+) in 31%, in both EDV and EF (EDV+/EF+) in 12% and neither EDV nor EF (EDV-/EF-) in 40%. The increase in EF was mainly and independently linked to a concomitant decline in TPVR (6-month change in mmHg.min.m2.L-1, EDV-/EF-: +1 ± 8, EDV+/EF-: +3 ± 9, EDV-/EF+: -7 ± 6, EDV+/EF+: -15 ± 20, p < 0.001) while the absence of any EF improvement was associated with high persisting rates of abnormally high TPVR at 6 months (EDV-/EF-: 31%, EDV+/EF-: 38%, EDV-/EF+: 5%, EDV+/EF+: 13%, p = 0.007). By contrast, the 6-month increase in EDV was mainly dependent on cardiac as opposed to vascular parameters and particularly on the presence of microvascular obstruction at baseline (EDV-/EF-: 37%, EDV+/EF-: 76%, EDV-/EF+: 38%, EDV+/EF+: 73%, p = 0.003).

CONCLUSION

LV remodeling following reperfused MI is strongly influenced by the variable decrease in systemic vascular resistance under standard care vasodilating medication. The CMR monitoring of vascular resistance may help to tailor these medications for improving vascular resistance and consequently, LV ejection fraction.

TRIAL REGISTRATION

NCT01109225 on ClinicalTrials.gov site (April, 2010).

The association of renin-angiotensin system blockades and pneumonia requiring admission in patients with COPD

BACKGROUND

The hallmark of COPD is chronic airway inflammation, which may be mediated by renin-angiotensin system. The renin-angiotensin system blockers such as angiotensin-converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (ARBs) have exhibited anti-inflammatory and immunomodulatory effects in patients with various diseases. We explored the effects of ACEi and ARBs on the risk of pneumonia in patients with COPD.

METHODS

A nested case-control study was performed on COPD patients recruited from January 2010 to August 2013 in two referral hospitals in Korea. A total of 130 COPD patients admitted with pneumonia were included, and 245 COPD patients without pneumonia were selected as controls from a total of 1,646 such patients. Controls were matched with test patients by age, sex, and severity of airflow limitation. The effects of ACEi/ARBs use on the odds ratio (OR) for the development of pneumonia were tested through conditional logistic regression.

RESULTS

Elderly patients (over 70 years of age) constituted ~30% of each group; most of the patients were male (85%). Of the COPD patients with pneumonia, 21.5% had taken ACEi/ARBs for a mean of 9.8 months (standard deviation ±3.5 months). The proportions of ACEi/ARBs users and the mean duration of such use did not differ when compared to those of the control patients (26.9%, P=0.25; 9.6±3.6 months, P=0.83). Univariate analyses indicated that the use of ACEi/ARBs was not associated with a decreased risk of pneumonia (OR =0.70, 95% confidence interval 0.41-1.23, P=0.21), whereas both a history of pulmonary tuberculosis (OR =1.85, 95% confidence interval 1.12-3.06, P=0.02) and exposure to systemic steroids (OR =2.33, 95% confidence interval 1.28-4.23, P=0.005) did show an association. After adjustment for a history of tuberculosis, comorbid chronic renal disease, and exposure to corticosteroids, ACEi/ARBs reduced the risk of pneumonia in COPD patients (OR =0.51, 95% confidence interval 0.27-0.98, P=0.04).

CONCLUSION

This study revealed that the use of ACEi/ARBs was associated with reducing the risk of pneumonia in patients with COPD. Further prospective studies are necessary to confirm the protective effect of ACEi/ARBs and elucidate the underlying mechanisms in COPD patients.

Association between higher rates of cardioprotective drug use and survival in patients on dialysis

BACKGROUND

While cardiovascular (CV) disease is a leading cause of morbidity and mortality in patients on chronic dialysis, utilization rates of cardioprotective drugs for dialysis patients remain low. This study sought to determine whether higher rates of cardioprotective drug use among dialysis patients might increase survival.

METHODS

A retrospective cohort of incident dialysis patients (n = 50,468) with dual eligibility for U.S. Medicare and Medicaid was constructed using USRDS data linked with billing claims. Medication exposures included angiotensin converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs), β-blockers, calcium channel blockers (CCBs), and HMG-CoA reductase inhibitors (statins) prescribed within 90 days of dialysis initiation. The outcomes were one- and two-year survival and CV event-free survival. Variation in treatment rates based on local area practice styles were used as instruments in instrumental variable (IV) estimation, yielding average treatment effect estimates for patients whose treatment choices were affected by local area practice styles.

RESULTS

Patients aged 65 years and older comprised 47.4% of the sample, while 59.5% were female and 35.0% were white. The utilization rate was 40.7% for ACEIs/ARBs, 43.0% for β-blockers, 50.7% for CCBs and 26.4% for statins. The local area practice style instruments were highly significantly related to cardioprotective drug use in dialysis patients (Chow-F values > 10). IV estimates showed only that higher rates of β-blockers increased one-year survival (β = 0.161, P-value = 0.020) and CV event-free survival (β = 0.189, P-value = 0.033), but that higher rates of CCBs decreased two-year CV event-free survival (β = -0.520, P-value = 0.009).

CONCLUSIONS

This study suggests that higher utilization rates of β-blockers might yield higher survival rates for dialysis patients. However, higher rates of the other drugs studied had no correlations with survival, and higher CCB rates might actually reduce CV-event free survival. Since the benefits of cardioprotective drugs may vary across dialysis patients, the study findings should be interpreted only with respect to changes of utilization rates around the rates observed in this study.

Activity prediction and molecular mechanism of bovine blood derived angiotensin I-converting enzyme inhibitory peptides

Development of angiotensin I-converting enzyme (ACE, EC 3.4.15.1) inhibitory peptides from food protein is under extensive research as alternative for the prevention of hypertension. However, it is difficult to identify peptides released from food sources. To accelerate the progress of peptide identification, a three layer back propagation neural network model was established to predict the ACE-inhibitory activity of pentapeptides derived from bovine hemoglobin by simulated enzyme digestion. The pentapeptide WTQRF has the best predicted value with experimental IC50 23.93 μM. The potential molecular mechanism of the WTQRF / ACE interaction was investigated by flexible docking.

The role of kinin receptors in cancer and therapeutic opportunities

Kinins are generated within inflammatory tissue microenvironments, where they exert diverse functions, including cell proliferation, leukocyte activation, cell migration, endothelial cell activation and nociception. These pleiotropic functions depend on signaling through two cross talking receptors, the constitutively expressed kinin receptor 2 (B2R) and the inducible kinin receptor 1 (B1R). We have reviewed evidence, which supports the concept that kinin receptors, especially kinin receptor 1, are promising targets for cancer therapy, since (1) many tumor cells express aberrantly high levels of these receptors; (2) some cancers produce kinins and use them as autocrine factors to stimulate their growth; (3) activation of kinin receptors leads to activation of macrophages, dendritic cells and other cells from the tumor microenvironment; (4) kinins have pro-angiogenic properties; (5) kinin receptors have been implicated in cancer migration, invasion and metastasis; and (6) selective antagonists for either B1R or B2R have shown anti-proliferative, anti-inflammatory, anti-angiogenic and anti-migratory properties. The multiple cross talks between kinin receptors and renin-angiotensin system (RAS) as well as its implications for targeting KKS or RAS for the treatment of malignancies are also discussed. It is expected that B1R antagonists would interfere less with housekeeping functions and therefore would be attractive compounds to treat selected types of cancer. Reliable clinical studies are needed to establish the translatability of these data to human settings and the usefulness of kinin receptor antagonists.

Pioglitazone, extract of compound Danshen dripping pill, and quercetin ameliorate diabetic nephropathy in diabetic rats

BACKGROUND

Oxidative stress appears to play a role in the pathogenesis of diabetes mellitus (DM), and disruption of the ubiquitin-proteasome system may underlie these pathological changes. We tested the effect of pioglitazone (PIO), an extract of Danshen dripping pill (DSP), and quercetin (QUE) on the pathogenesis of DM in a rat model.

METHODS

Male Sprague Dawley rats were maintained in a normal control (NC) group or given a modified diet and streptozotocin (STZ) to induce DM. After STZ treatment, rats were given intragastric placebo, PIO, DSP, or QUE for 8 weeks. At the end of the treatment period, serum and urine chemistry, renal hypertrophy, renal histopathology, and renal expression of ubiquitin and nuclear factor (NF)-κB p65 were analyzed.

RESULTS

DM rats had altered body and kidney weight, altered serum and urine chemistry, increased accumulation of glomerular extracellular matrix (ECM), and increased renal expression of ubiquitin and NF-κB p65, indicating successful establishment of our DM model. Treatment with PIO, DSP, or QUE significantly ameliorated these pathological changes, although treated rats still had some symptoms of DM.

CONCLUSION

DM rats have increased expression of ubiquitin and NF-κB p65 in their renal tubules and glomeruli. PIO, DSP, and QUE ameliorated the pathological changes associated with DM and also reduced the renal expression of ubiquitin and NF-κB p65. These agents may provide protection from renal pathology associated with DM due to their anti-oxidant effects.

Activation of the kinin B1 receptor attenuates melanoma tumor growth and metastasis

Melanoma is a very aggressive tumor that does not respond well to standard therapeutic approaches, such as radio- and chemotherapies. Furthermore, acquiring the ability to metastasize in melanoma and many other tumor types is directly related to incurable disease. The B1 kinin receptor participates in a variety of cancer-related pathophysiological events, such as inflammation and angiogenesis. Therefore, we investigated whether this G protein-coupled receptor plays a role in tumor progression. We used a murine melanoma cell line that expresses the kinin B1 receptor and does not express the kinin B2 receptor to investigate the precise contribution of activation of the B1 receptor in tumor progression and correlated events using various in vitro and in vivo approaches. Activation of the kinin B1 receptor in the absence of B2 receptor inhibits cell migration in vitro and decreases tumor formation in vivo. Moreover, tumors formed from cells stimulated with B1-specific agonist showed several features of decreased aggressiveness, such as smaller size and infiltration of inflammatory cells within the tumor area, higher levels of pro-inflammatory cytokines implicated in the host anti-tumor immune response, lower number of cells undergoing mitosis, a poorer vascular network, no signs of invasion of surrounding tissues or metastasis and increased animal survival. Our findings reveal that activation of the kinin B1 receptor has a host protective role during murine melanoma tumor progression, suggesting that the B1 receptor could be a new anti-tumor GPCR and provide new opportunities for therapeutic targeting.

Angiotensin-(1-7) reduces proliferation and angiogenesis of human prostate cancer xenografts with a decrease in angiogenic factors and an increase in sFlt-1

BACKGROUND

Prostate cancer is the most frequently diagnosed malignancy and the second-leading cause of cancer death in men. The purpose of this study was to determine the anti-proliferative and anti-angiogenic efficacy of angiotensin-(1-7) [Ang-(1-7)], an endogenous peptide hormone, in human prostate cancer xenografts.

METHODS

Human LNCaP prostate cancer cells were injected into the flank of athymic mice and tumors were treated with Ang-(1-7) for 54 days. Tumor growth and angiogenesis were determined by immunohistochemistry and western blot hybridization.

RESULTS

Ang-(1-7) markedly reduced the volume and wet weight of LNCaP xenograft tumors. Histological analysis of tumor sections from saline-treated mice showed increased Ki67 immunoreactivity and enhanced phosphorylation of the MAP kinases ERK1/2 compared to tumors from Ang-(1-7)-treated mice, suggesting that the heptapeptide reduces cell proliferation. Intratumoral vessel density was decreased in Ang-(1-7)-treated mice with an associated reduction in vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), suggesting that the heptapeptide attenuates vascularization by reducing angiogenic factors. Ang-(1-7) administration markedly increased the soluble fraction of VEGF receptor 1 (sFlt-1), with a concomitant reduction in VEGF receptors 1 and 2. sFlt-1 serves as a decoy receptor that traps VEGF and PlGF, making the ligands unavailable to membrane-bound VEGF receptors and preventing activation of pro-angiogenic signaling.

CONCLUSIONS

The decrease in PlGF and VEGF coupled with the increase in sFlt-1 suggests that Ang-(1-7) may serve as a novel anti-angiogenic therapy for prostate cancer. Further, the pleiotropic mechanisms of action by Ang-(1-7) may limit angiogenic resistance that occurs with VEGF inhibitors or receptor blockers.

Renin-angiotensin system blockade: a novel therapeutic approach in chronic obstructive pulmonary disease

ACE (angiotensin-converting enzyme) inhibitors and ARBs (angiotensin II receptor blockers) are already widely used for the treatment and prevention of cardiovascular disease and their potential role in other disease states has become increasingly recognized. COPD (chronic obstructive pulmonary disease) is characterized by pathological inflammatory processes involving the lung parenchyma, airways and vascular bed. The aim of the present review is to outline the role of the RAS (renin-angiotensin system) in the pathogenesis of COPD, including reference to results from fibrotic lung conditions and pulmonary hypertension. The review will, in particular, address the emerging evidence that ACE inhibition could have a beneficial effect on skeletal muscle function and cardiovascular co-morbidity in COPD patients. The evidence to support the effect of RAS blockade as a novel therapeutic approach in COPD will be discussed.

Top Three Pharmacogenomics and Personalized Medicine Applications at the Nexus of Renal Pathophysiology and Cardiovascular Medicine

Pharmacogenomics is a field with origins in the study of monogenic variations in drug metabolism in the 1950s. Perhaps because of these historical underpinnings, there has been an intensive investigation of 'hepatic pharmacogenes' such as CYP450s and liver drug metabolism using pharmacogenomics approaches over the past five decades. Surprisingly, kidney pathophysiology, attendant diseases and treatment outcomes have been vastly under-studied and under-theorized despite their central importance in maintenance of health, susceptibility to disease and rational personalized therapeutics. Indeed, chronic kidney disease (CKD) represents an increasing public health burden worldwide, both in developed and developing countries. Patients with CKD suffer from high cardiovascular morbidity and mortality, which is mainly attributable to cardiovascular events before reaching end-stage renal disease. In this paper, we focus our analyses on renal function before end-stage renal disease, as seen through the lens of pharmacogenomics and human genomic variation. We herein synthesize the recent evidence linking selected Very Important Pharmacogenes (VIP) to renal function, blood pressure and salt-sensitivity in humans, and ways in which these insights might inform rational personalized therapeutics. Notably, we highlight and present the rationale for three applications that we consider as important and actionable therapeutic and preventive focus areas in renal pharmacogenomics: 1) ACE inhibitors, as a confirmed application, 2) VDR agonists, as a promising application, and 3) moderate dietary salt intake, as a suggested novel application. Additionally, we emphasize the putative contributions of gene-environment interactions, discuss the implications of these findings to treat and prevent hypertension and CKD. Finally, we conclude with a strategic agenda and vision required to accelerate advances in this under-studied field of renal pharmacogenomics with vast significance for global public health.

Use of angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers and cancer risk: a meta-analysis of observational studies

BACKGROUND

Epidemiologic studies have reported inconsistent findings regarding the association between the use of angiotensin-converting-enzyme (ACE) inhibitors or angiotensin-receptor blockers and the risk of cancer. We performed a meta-analysis of observational studies to assess the association.

METHODS

We searched MEDLINE, EMBASE and the Cochrane Library to identify studies through January 2011. Two evaluators independently reviewed and selected articles of cohort and case-control studies on the basis of predetermined selection criteria.

RESULTS

Of 3970 screened articles, 12 cohort studies and 16 case-control studies were selected for analysis. We found no significant association between the use of ACE inhibitors or angiotensin-receptor blockers and the overall risk of cancer (relative risk [RR] 0.96, 95% confidence interval [CI] 0.90-1.03). We found a decreased risk of cancer associated with use of either medication when we restricted the analyses to cohort and nested case-control studies (RR 0.90, 95% CI 0.83-0.97) or to studies with long-term follow-up of more than five years (RR 0.89, 95% CI 0.83-0.96). In the subgroup meta-analyses by cancer site, a decreased risk was identified for esophageal cancer, whereas an increased risk was found for melanoma and kidney cancer.

INTERPRETATION

No significant association was found between the use of ACE inhibitors or angiotensin-receptor blockers and overall risk of cancer. A possible beneficial effect associated with use of either medication was suggested in sensitivity analyses, including those of studies with long-term follow-up. Large randomized controlled trials with long-term follow-up are needed to specifically test the effect of each of these medications on the risk of cancer.

Effect of treatment of high fat fed/low dose streptozotocin-diabetic rats with Ilepatril on vascular and neural complications

We have previously shown that treating streptozotocin-induced diabetic rats, an animal model of type 1 diabetes, with Ilepatril (an inhibitor of neutral endopeptidase and angiotensin converting enzyme (ACE)) improves vascular and neural functions. In this study we sought to determine the effect of Ilepatril treatment of high fat fed/low dose streptozotocin-diabetic rats, a model for type 2 diabetes, on vascular and neural complications. Following 8 weeks on a high fat diet rats were treated with 30 mg/kg streptozotocin (i.p.) and after 4 additional weeks a group of these rats was treated for 12 weeks with Ilepatril followed by analysis of neural and vascular functions. Included in these studies were age-matched control rats and rats fed a high fat diet and treated with or without Ilepatril. Diabetic and diet induced obese rats have characteristics of insulin resistance, slowing of nerve conduction velocity, thermal hypoalgesia, reduction in intraepidermal nerve fiber density in the hindpaw and impairment in vascular relaxation to acetylcholine and calcitonin gene-related peptide in epineurial arterioles of the sciatic nerve. Treatment with Ilepatril was efficacious in improving all of these endpoints although improvement of insulin resistance in diabetic rats was minimal. These studies suggest that dual inhibition of angiotensin converting enzyme and neutral endopeptidase activity of type 2 diabetic rats is an effective approach for treatment of diabetic neural and vascular complications.

Antihypertensive effects exerted by enalapril in mild to moderate hypertension are not associated with changes in the circulating levels of nitric oxide-related markers

PURPOSE

The antihypertensive effects of angiotensin-converting enzyme inhibitors (ACEi) are explained, at least in part, by enhanced bradykinin-dependent nitric oxide (NO) formation and decreased angiotensin II-induced oxidative stress and vasoconstriction. We examined for the first time whether treatment with enalapril increases the plasma levels of markers of NO formation and decreases oxidative stress in mild to moderate hypertensive patients.

METHODS

Eighteen untreated hypertensive patients were treated with enalapril 10 mg/day (n=10) or 20 mg/day (n=8) for 60 days. Eighteen normotensive healthy controls were followed for the same period. Venous blood samples were collected at baseline and after 30/60 days of treatment with enalapril. Plasma NOx (nitrites + nitrates) concentrations were determined by using the Griess reaction. Plasma nitrite and whole blood nitrite concentrations were determined by using an ozone-based chemiluminescence assay. Plasma thiobarbituric acid-reactive species (TBARS) and 8-isoprostane concentrations were determined by a fluorimetric method and by ELISA, respectively.

RESULTS

Treatment with enalapril decreased blood pressure in hypertensive patients. However, we found no significant changes in plasma NOx, nitrite, whole blood nitrite, and in the levels of markers of oxidative stress in both normotensive controls and hypertensive patients treated with enalapril.

CONCLUSIONS

Our data show that enalapril 10-20 mg/day does not affect the concentrations of relevant markers of NO formation or markers of oxidative stress in mild to moderately hypertensive subjects, despite satisfactory blood pressure control. Our findings do not rule out the possibility that ACEi may produce such effects in more severely hypertensive patients treated with higher doses of ACEi.

Have the renin-angiotensin-aldosterone system perturbations in cardiovascular disease been exhausted?

The renin-angiotensin-aldosterone system (RAAS) plays an important role in blood pressure control and volume homeostasis. Inappropriate activation of the RAAS has been implicated in the pathogenesis of hypertension and related cardiovascular disease. Several classes of agents that block RAAS signaling have been shown to be effective antihypertensives and to have cardioprotective and renoprotective properties. Because blockade of the RAAS is incomplete with any of the currently available monotherapies, combinations of these agents have been tested and shown to provide additional clinical benefit in patients with hypertension and various forms of cardiovascular and renal disease.

Role of the effect of inhibition of neutral endopeptidase on vascular and neural complications in streptozotocin-induced diabetic rats

We have previously shown that treating streptozotocin-induced diabetic rats, an animal model of type 1 diabetes, with Ilepatril (an inhibitor of neutral endopeptidase and angiotensin converting enzyme (ACE)) improves vascular and neural function. In this study we sought to determine the individual effect of inhibition of neutral endopeptidase and ACE on diabetes-induced vascular and neural dysfunction. After 4 weeks of untreated diabetes, rats were treated for 12 weeks with Ilepatril, Enalapril (ACE inhibitor) or Candoxatril (neutral endopeptidase inhibitor) followed by analysis of neural and vascular function. Diabetes caused slowing of motor and sensory nerve conduction, thermal hypoalgesia, reduction in intraepidermal nerve fiber density in the hindpaw and impairment in vascular relaxation to acetylcholine and calcitonin gene-related peptide in epineural arterioles of the sciatic nerve and to atrial natriuretic peptide and calcitonin gene-related peptide in renal arteries. Inhibition of neutral endopeptidase or ACE improved neural function; however, dual inhibition of neutral endopeptidase and ACE with Ilepatril tended to have the greatest efficacy. Ilepatril and Candoxatril treatment of diabetic rats was more efficacious in improving vascular responsiveness in epineurial arterioles than treatment with Enalapril. Ilepatril, Enalapril or Candoxatril treatment of diabetic rats were all efficacious in renal arteries. These studies suggest that combination therapy may be the most effective approach for treatment of diabetic neural and vascular complications.

Autonomic nervous system and nitric oxide in antihypertensive and cardiac inhibitory effects induced by red mold rice in spontaneously hypertensive rats

The aim of this study was to investigate the antihypertensive activity of the ethanol extract (EE) of red mold rice (RMR) and to explore its mechanism of action. In comparison to EE of nonfermented rice, the EE of RMR contained higher levels of total phenolic, total flavonoids, gamma-aminobutyric acid, and monacolin K. Intravenous bolus administration of the EE (10-50 mg/kg) resulted in biphasic, dose-dependent antihypertensive effects and decreases in heart rate, cardiac contractility, and sympathetic vasomotor tone in spontaneously hypertensive rats. The initial and delayed antihypertensive responses, and the negative inotropic and chronotropic effects of EE treatment (30 mg/kg, i.v.) were significantly reduced by pretreatment with hexamethonium (30 mg/kg, i.v.) and N(G)-nitro-l-arginine methyl ester (20 mg/kg, i.v.). Pretreatment with methylatropine (1 mg/kg, i.v.), however, reversed the initial but not the delayed bradycardiac and negative inotropic effects of EE. We conclude that systemic administration of the EE of RMR elicited both transient and delayed antihypertensive actions that were mediated by the withdrawal of sympathetic tone and the production of nitric oxide (NO). The negative inotropic and chronotropic effects of EE may result from a direct sympathetic inhibition of the heart as well as an activation of the NO-dependent pathway.