Angiotensin II-converting Enzyme Research Articles

Renoprotective Effects of Mineralocorticoid Receptor Antagonists Against Diabetic Kidney Disease.

Diabetic kidney disease (DKD) is a growing epidemic worldwide and a leading cause of end-stage kidney disease. Mineralocorticoid receptor (MR) blockade using Finerenone is a recently approved therapeutic approach to slow down the progression of DKD in patients with type 2 diabetes in addition to other therapies such as angiotensin-II converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), sodium-glucose co-transporter 2 (SGLT2) inhibitors, and glucagon-like peptide 1 (GLP-1) analogs. This review elaborates on the pathophysiologic pathways activated by aldosterone (the human mineralocorticoid) in DKD, the pharmacology of three different generations of mineralocorticoid receptor antagonists (MRAs), specifically, spironolactone, eplerenone, and finerenone, and the mechanisms by which these MRAs elicit their protective effects on the kidney under diabetic settings.

Angiotensinergic and GABAergic transmission in the medial preoptic area: role in urinary bladder and cardiovascular control in female rats.

Introduction: The medial preoptic area (mPOA) participates in thermoregulatory control and blood pressure modulation as shown by studies with electrical stimulation of this area or cobalt chloride injection, a non-selective synapse inhibitor. This study aimed to investigate whether angiotensin II (Ang II) and GABA could act or not in the mPOA to mediate the cardiovascular and micturition control pathways. Methods: Female Wistar rats were submitted to stereotaxic surgery for implantation of a guide cannula into the mPOA 7days prior to the experiments. Afterwards, the animals were isoflurane- anesthetized and submitted to the catheterization of the femoral artery and vein and urinary bladder cannulation for mean arterial pressure (MAP), heart rate (HR), and intravesical pressure (IP) recordings, respectively. After the baseline MAP, HR, and IP recordings for 15min, Ang II (0.1nM, 1μL), losartan (AT-1 receptor antagonist, 100nM, 1μL), GABA (50mM, 1μL) or saline (1μL) were injected into the mPOA, and the variables were measured for additional 30min. In a different group of rats, the AT-1 receptor, angiotensin II converting enzyme (ACE), and GABAa receptor gene expression was evaluated in mPOA samples by qPCR. The data are as mean ± SEM and submitted to One-way ANOVA (Tukey posttest) or paired Student t-test (P <0.05). Results: The injection of Ang II into the mPOA evoked a significant hypotension (-37±10mmHg, n = 6, p = 0.024) and bradycardia (-47 ± 20bpm, p = 0.030) compared to saline (+1 ± 1mmHg and +6 ± 2bpm, n = 6). A significant increase in IP was observed after Ang II injection into the mPOA (+72.25 ± 17.91%, p = 0.015 vs. -1.80 ± 2.98%, n = 6, saline). No significant changes were observed in MAP, HR and IP after the losartan injection in the mPOA compared to saline injection. Injection of GABA into the mPOA evoked a significant fall in MAP and HR (-68 ± 2mmHg, n = 6, p < 0.0001 and -115 ± 14bpm, n = 6, p = 0.0002 vs. -1 ± 1mmHg and +4 ± 2bpm, n = 6, saline), but no significant changes were observed in IP. The AT-1 receptor, ACE and GABAa receptor mRNA expression was observed in all mPOA samples. Discussion: Therefore, in female rats, Ang II mediated transmission in the mPOA is involved in the cardiovascular regulation and in the control of central micturition pathways. A phasic control dependent on AT-1 receptors in the mPOA seems to be involved in the regulation of those cardiovascular and intravesical 3 parameters. In contrast, GABAergic transmission in the mPOA participates in the pathways of cardiovascular control in anesthetized female rats, nevertheless, this neurotransmission is not involved in the micturition control.

COVID-19 and the Use of Angiotensin II Receptor Blockers in Older Chronic Hypertensive Patients: Systematic Review and Meta-Analysis.

Angiotensin II-converting enzyme inhibitors (ACEIs) and selective angiotensin II receptor antagonists (ARAIIs) are widely used antihypertensive agents. Their use has generated controversy due to their possible influence on the health status of chronic patients infected with COVID-19. The objective of this work is to analyze the influence of COVID-19 on chronic hypertensive patients treated with ACEI and ARAII inhibitors. A systematic review and meta-analysis in the databases Pubmed, Pro-Quest and Scopus were carried out. The systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search equation descriptors were obtained from the Medical Subject Headings (MeSH) thesaurus. The search equation was: "Older AND hypertension AND (COVID-19 OR coronavirus) AND primary care" and its equivalent in Spanish. Nineteen articles were obtained, with n = 10,806,159 subjects. Several studies describe the COVID-19 association with ACEI or ARAII treatment in hypertension patients as a protective factor, some as a risk factor, and others without a risk association. In the case of ACEI vs. ARAII, the risk described for the former has an odds ratio (OR) of 0.55, and for ARAII, an OR of 0.59. Some authors talk about mortality associated with COVID-19 and ACEI with a half ratio (HR) of 0.97, and also associated ARAIIs with an HR of 0.98. It is recommended to maintain the use of the renin-angiotensin-aldosterone axis in the context of the COVID-19 disease.

Sacubitril/Valsartan in Dialysis Patients: Update on Current Perspectives.

Sacubitril/Valsartan is a combination of neprilysin inhibitor and angiotensin II receptor blocker that proved its own efficacy and safety in heart failure patients to ameliorate cardiovascular morbidity and mortality compared to angiotensin II-converting enzyme inhibitors alone. However, end-stage renal disease patients have not been included in the randomized controlled trials, so the beneficial effects as well as the risk profile of this association remain still undefined in these patients. Only observational studies on this drug association have been carried out in end-stage renal disease patients investigating mostly biohumoral or echocardiographic markers. Therefore, its application is still controversial and not free of complications due to the potential risk of hypotension and hyperkaliemia. The efficacy to improve biohumoral markers and cardiac function in dialysis patients and the potential application especially in those patients with severe and resistant hypertension and/or left ventricular dysfunction could be crucial in end-stage renal disease patients. Ongoing long-term randomized controlled trials should thoroughly define the effective benefits and/or adverse effects in patients on substitutive treatment.

Baculovirus-Free SARS-CoV-2 Virus-like Particle Production in Insect Cells for Rapid Neutralization Assessment.

Virus-like particles (VLPs) resemble authentic virus while not containing any genomic information. Here, we present a fast and powerful method for the production of SARS-CoV-2 VLP in insect cells and the application of these VLPs to evaluate the inhibition capacity of monoclonal antibodies and sera of vaccinated donors. Our method avoids the baculovirus-based approaches commonly used in insect cells by employing direct plasmid transfection to co-express SARS-CoV-2 envelope, membrane, and spike protein that self-assemble into VLPs. After optimization of the expression plasmids and vector ratios, VLPs with an ~145 nm diameter and the typical “Corona” aura were obtained, as confirmed by nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). Fusion of the membrane protein to GFP allowed direct quantification of binding inhibition to angiotensin II-converting enzyme 2 (ACE2) on cells by therapeutic antibody candidates or sera from vaccinated individuals. Neither VLP purification nor fluorescent labeling by secondary antibodies are required to perform these flow cytometric assays.

Effects of angiotensin peptides on colonic motility in rats.

Renin-angiotensin system (RAS) is involved in the pathophysiology of colonic inflammation. The aim of this study was to investigate whether small angiotensins (Angs) peptides play a role in the regulation of colonic motility and their roles are modulated in colitis. Experimental colitis was induced by an intake of 5% dextran sulfate sodium (DSS) dissolved in tap water for 7 days in Sprague-Dawley rats. After sacrifice, plasma hormone concentrations and messenger RNAs (mRNAs) for RAS were measured. Functional analysis of colonic motility in response to Angs peptides was performed using Taenia coli. DSS-treated colon showed an increased necrosis with massive infiltration of inflammatory cells. The mRNA level of colonic angiotensin II receptor type 2 (AT2R) in DSS-treated rats was higher than that in control rats whereas the mRNA levels of angiotensin II converting enzyme (ACE), ACE2, AT1R, AT4R, and Mars receptor were not different from those in control rats. Ang III, Ang IV, and Ang-(1-9) (1, 3 μM) increased the frequency of basal colonic motility. Ang-(1-7) did not cause any significant changes in frequency and amplitude of basal motility. The order of potency for an increased frequency of basal motility seems to be Ang II>>Ang IV>Ang III=Ang-(1-9). The increased frequency of basal motility by Ang-(1-9) but not Ang IV was significantly enhanced in DSS-treated rat colon. In conclusion, these data suggest that small Angs peptides are partly involved in the pathophysiological regulation of colonic motility in experimental colitis.

Abstract LB075: Development of SARS-CoV-2 neutralizing protein by ACE2 receptor engineering for severe infection and patients with underlying diseases

Abstract Since the Spike protein on the surface of SARS coronavirus 2 (SARS-CoV-2) binds to the ACE2 receptor in human cells, the development of neutralizing proteins or antibodies targeting the receptor binding domain (RBD) of the spike protein is an important strategy for SARS-COV-2 therapy. We chose to develop molecularly-evolved soluble ACE2 protein on three grounds; 1) it can trap and neutralize the SARS-CoV-2 as neutralizing antibodies do, 2) it can supplement angiotensin II-converting enzyme activities that protect lung, heart, and kidneys of severe cases of infections and patients with underlying diseases, and 3) it may trap effectively SARS-CoV-2 mutants even though the mutations compromise the protection by neutralizing antibodies or vaccine. For the enhancement of ACE2 binding affinity to RBD, we used the 3D complex structure between ACE2 and RBD to select the major contributing ACE2 amino acids, a library targeting selected amino acids and random mutations were constructed and screened using yeast surface display. The engineered ACE2, EU129, was fused with the human IgG1 Fc for long half-life and viral clearance. The binding affinity of EU129 to RBD was increased by about 500-folds compared to ACE2 wild-type in SPR analysis, and the neutralizing activity was also increased by about 130-folds compared to ACE2 wild-type in surrogate virus neutralization test (sVNT). In addition, it was confirmed that the enzymatic activity of ACE2, which prevents organ damage due to SARS-CoV-2 infection in the human, is maintained at a level similar to that of ACE2 wild-type. In vitro assays using live SARS-CoV-2 virus and Vero E6 cells, EU129 was shown to be more effective in inhibiting viral infection and amplification than ACE2 wild-type, which was confirmed through protein and RNA level and cell morphology change of the live virus. In vivo stability assays using BALB/c mice, EU129 showed enhanced binding to the RBD and maintained enzymatic activity similar to ACE2 wild-type. We generated EU129 with the improved binding affinity and neutralizing activity through ACE2 receptor engineering. It has angiotensin II-converting enzymatic activity for organ protection, thus EU129 is a better therapeutic candidate for severe cases of SARS-CoV-2 infection and patients with underlying diseases such as cancers. Citation Format: Byoung S. Kwon, Seunghyun Lee, Jin-Kyung Choi, Bora Hwang, Sun-Woo Im, Yun-Sook Lim, Bumseok Kim, Soon B. Hwang, HoonSung Jeh. Development of SARS-CoV-2 neutralizing protein by ACE2 receptor engineering for severe infection and patients with underlying diseases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB075.

Polygalacto-fucopyranose from marine alga as a prospective antihypertensive lead

Consumption of marine alga-based polysaccharides as additional functional foods can endow with health benefits by diminishing the risk of chronic diseases. A polygalacto-fucopyranose characterized as [→1)-2, 4-SO3-α-Fucp-(3 → 1)-{2-SO3-α-Fucp-(3→}] with [(4 → 1)-6-OAc-β-Galp-(4→] side chain isolated from marine alga Sargassum wightii exhibited potential antihypertensive activity. Upon treatment with studied polygalactofucan (50 mg/kg BW), serum hypertension biomarkers troponin-T (1.3 pg/mL), troponin-I (1.2 μg/dL) and angiotensin-II converting enzyme (0.18 pg/mL) were significantly recovered in hypertensive rats compared to disease control. Serum cardiovascular risk indices of diseased rats were significantly decreased (< 10%, p < 0.05) after administration of the studied galactofucan (50 mg/kg BW) related to hypertension group (> 17%), and were comparable with standard antihypertensive agent telmisartan (8.3–10.2% at 2 mg/kg BW). The studied compound was safe for consumption as obvious from the high LD50 value (>5 g/kg), and could be developed as a prospective functional food ingredient attenuating the pathophysiological attributes causing hypertension-related conditions.

Breastfeeding importance and its therapeutic potential against SARS-CoV-2.

During postnatal development, colostrum and breastmilk are sequentially the first sources of nutrition with protein components and bioactive molecules that confer protection and immunostimulatory function to the gut. Caseins, whey proteins, secretory immunoglobulin A (sIgA), mucins, tryptophan, and growth factors are among milk‐borne elements that are directly important in the control of mucosa development and protection. Consequently, breastfeeding is associated with the low incidence of gastrointestinal inflammation and with the decrease in respiratory diseases during postnatal period. The novel coronavirus (SARS‐CoV‐2) binds to angiotensin II‐converting enzyme (ACE2) on the cell membrane, allowing virus entrance, replication, and host commitment. ACE2 is expressed by different cell types, which include ciliated cells in the lungs and enterocytes in the intestine. Such cells are highly active in metabolism, as they internalize molecules to be processed and used by the organism. The disruption of ACE2 impairs leads to intestinal inflammation and decreased synthesis of serotonin, affecting motility. By reviewing the effects of SARS‐CoV‐2 in the gastrointestinal and respiratory tracts in infants, and gut responses to breastfeeding interruption, we suggest that it is important to maintain breastfeeding during SARS‐CoV‐2 infection, as it might be essential to protect newborns from gastrointestinal‐associated disorders and relieve disease symptoms.

Computational insights into the membrane fusion mechanism of SARS-CoV-2 at the cellular level

The membrane fusion mechanism of SARS-CoV-2 offers an attractive target for the development of small molecule antiviral inhibitors. Fusion involves an initial binding of the crown-like trimeric spike glycoproteins of SARS-CoV-2 to the receptor angiotensin II-converting enzyme 2 (ACE2) on the permissive host cellular membrane and a prefusion to post-fusion conversion of the spike trimer. During this conversion, the fusion peptides of the spike trimer are inserted into the host membrane to bring together the host and viral membranes for membrane fusion in highly choreographic events. However, geometric constraints due to interactions with the membranes remain poorly understood. In this study, we build structural models of super-complexes of spike trimer/ACE2 dimers based on the molecular structures of the ACE2/neutral amino acid transporter B(0)AT heterodimer. We determine the conformational constraints due to the membrane geometry on the enzymatic activity of ACE2 and on the viral fusion process. Furthermore, we find that binding three ACE2 dimers per spike trimer is essential to open the central pore as necessary for triggering productive membrane fusion through an elongation of the central stalk. The reported findings thus provide valuable insights for targeting the membrane fusion mechanism for drug design at the molecular level.

Angiotensin axis antagonists increase the incidence of haemodynamic instability in dihydropyridine calcium channel blocker poisoning

Context Amlodipine, a dihydropyridine calcium channel blocker (CCB), is the leading cause of cardiovascular drug-related overdose deaths in the USA. In contrast, angiotensin-II receptor blockers (ARBs) and angiotensin converting enzyme inhibitors (ACEIs) cause minimal toxicity in overdose. ACEIs/ARBs are often combined with dihydropyridines in hypertension treatment. Co-ingested ARBs/ACEIs may significantly contribute to the toxicity of dihydropyridine, but this has not been investigated. Objective To investigate the clinical outcomes from dihydropyridine overdoses with ARBs/ACEIs versus dihydropyridine overdoses alone. Methods This was a retrospective study of patients reported to the New South Wales Poisons Information Centre (NSW PIC) and 3 toxicology units (Jan 2016 to Jun 2019) in Australia. Patients >14 years who took an overdose of dihydropyridines (amlodipine, felodipine, lercanidipine, nifedipine) were included. Concurrent overdoses with non-dihydropyridine CCBs, alpha-blockers and beta-blockers were excluded. Patient demographics, drugs exposure details, serial vital signs, treatments and outcome were collected. Results There were 100 patients. 68 took mixed overdoses of dihydropyridines with ARBs/ACEIs and 32 took single overdoses of dihydropyridines without ARBs/ACEIs. The mixed group had lower median nadir mean arterial pressures (62 vs 75 mmHg, p < 0.001), more frequently had hypotension (OR 4.5, 95%CI: 1.7–11.9) or bradycardia (OR 8.8, 95%CI: 1.1–70). Multivariable analysis indicated the mixed overdoses had an 11.5 mmHg (95%CI: 4.9–18.1) lower minimum systolic blood pressure (SBP) compared with the single group; other factors associated with a lower minimum SBP were higher doses [2.3 mmHg (95%CI: 1.1–3.5) lower per 10 defined daily doses] and younger age [2.2 mmHg (95%CI: 0.3–4.2) higher per decade]. A larger proportion of the mixed ingestion group received intravenous fluids (OR 5.7, 95%CI: 1.8–18.6) and antidotes and/or vasopressors (OR 2.9, 95%CI: 1.004–8.6). Conclusion Combined overdoses of dihydropyridines with ARBs/ACEIs caused more significant hypotension and required more haemodynamic support than overdoses of dihydropyridines alone.

Human Endomyocardial Biopsy Specimen-Derived Stromal Cells Modulate Angiotensin II-Induced Cardiac Remodeling.

Despite effective pharmacological treatment with angiotensin II type I receptor antagonists or angiotensin II-converting enzyme inhibitors, morbidity and mortality associated with heart failure are still substantial, prompting the search of novel therapeutic strategies. There is accumulating evidence supporting the use of cell therapy for cardiac repair. This study demonstrates that cells derived from human endomyocardial biopsies, cardiac-derived adherent proliferating cells (CardAPs), have the potential to reduce angiotensin II-induced cardiac remodeling and improve left ventricular function in angiotensin II mice. The mechanism involves antifibrotic and antihypertrophic effects via paracrine actions and immunomodulatory properties. These findings support the potential of CardAPs for the treatment of heart failure.

Recent trends in the use of antidiabetic medications from 2008 to 2013: A nation-wide population-based study from Taiwan.

Studies from other countries indicate that utilization patterns of antidiabetic drugs change significantly after the introduction of newer classes of antidiabetic drugs (e.g. dipeptidyl peptidase-4 inhibitors [DPP-4i]). Evidence on recent trends regarding antidiabetic drug use in Taiwan is lacking, especially for times after the introduction of newer classes of drugs (e.g. DPP-4i). Therefore, the aim of the present study was to assess: (i) recent trends in the use and spending on antidiabetic drugs; (ii) changes in utilization patterns after introduction of newer classes of antidiabetic drugs; and (iii) factors associated with the choice of newer versus older classes of antidiabetic drugs. Cases of type 2 diabetes were derived from Taiwan's National Health Insurance Research Database. Antidiabetic drug use was measured in terms of total quantity of drug exposure and healthcare spending in each calendar year from 2008 to 2103. Multiple logistic regression analysis was used to assess factors associated with drug choice. The use of and healthcare spending on DPP-4i increased significantly from 2008 to 2013, whereas healthcare spending on sulfonylureas decreased. For monotherapy, sulfonylureas were the most common alternatives to metformin, whereas in dual and triple antidiabetic therapies, a DPP-4i was the most common alternative to initial regimens. The use of a DPP-4i was positively associated with the use of beta-blockers, angiotensin II-converting enzyme inhibitors and/or angiotensin receptor blockers, and lipid-lowering agents, but negatively correlated with age, hypertension, severity of diabetes complications, and the use of diuretics and calcium channel blockers. With growing spending on newer antidiabetic drugs, future research on the comparative cost-effectiveness and safety of antidiabetic drugs is anticipated.

Enalapril in Combination with Benznidazole Reduces Cardiac Inflammation and Creatine Kinases in Mice Chronically Infected with Trypanosoma cruzi.

The protozoan Trypanosoma cruzi triggers an inflammatory process in mammalian heart causing events such as fibrosis, changes in the architecture and functionality in this organ. Enalapril, an angiotensin II-converting enzyme inhibitor, is a drug prescribed to ameliorate this heart dysfunction, and appears to exert a potential role in immune system regulation. Our aim was to evaluate the chronic cardiac inflammatory parameters after therapeutic treatment with enalapril and benznidazole in C57BL/6 mice infected with the VL-10 strain of T. cruzi. After infection, animals were treated with oral doses of enalapril (25 mg/kg), benznidazole (100 mg/kg), or both during 30 days. Morphometric parameters and levels of chemokines (CCL2, CCL5), IL-10, creatine kinases (CKs), and C-reactive protein were evaluated in the heart and serum at the 120th day of infection. Enalapril alone or in combination with benznidazole did not change the number of circulating parasites, but reduced cardiac leukocyte recruitment and total collagen in the cardiac tissue. Interestingly, the combination therapy (enalapril/benznidazole) also reduced the levels of chemokines, CK and CK-MB, and C-reactive proteins in chronic phase. In conclusion, during the chronic experimental T. cruzi infection, the combination therapy using enalapril plus benznidazole potentiated their immunomodulatory effects, resulting in a low production of biomarkers of cardiac lesions.

Characterization of the renal renin-angiotensin system in transgenic mice that express rat tonin.

Tonin is an enzyme that is able to generate angiotensin II (Ang II) from angiotensin I (Ang I) or directly from angiotensinogen. Our goal was to characterize the renal renin-angiotensin system in transgenic mice that express rat tonin (TGM`(rTon)). Mice were euthanized and the kidneys removed for analysis. Tonin activity was evaluated by radioimmunoassay and angiotensin I-converting enzyme (ACE) activity by HPLC. Tonin, ACE and angiotensin II-converting enzyme (ACE2) expression was analyzed by Western blotting. Tonin activity was significantly increased in TGM`(rTon) compared to their respective wild-type (WT) littermates (1.7 ± 0.21 vs 0.11 ± 0.02 nmol of Ang II/min/mg of protein). Tonin activity had a strong positive correlation with tonin expression in both TGM`(rTon) and their respective wild-type littermates. The ACE activity and expression levels of 65-kDa N-domain angiotensin I-converting enzyme isoform were significantly increased in the TGM`(rTon) when compared with WT. ACE2 expression levels were statistically significantly higher in the TGM`(rTon) when compared with WT. Angiotensin 1-7 (Ang(1-7)) and Ang I levels were significantly lower in the TGM`(rTon). We suggest that the environment of tonin abundance may increase N-domain ACE activity liberated by a secretase able to cleave somatic ACE.

Mitogen-activated protein kinase kinase 1/2 inhibition and angiotensin II converting inhibition in mice with cardiomyopathy caused by lamin A/C gene mutation

BackgroundMutations in the LMNA gene encoding A-type nuclear lamins can cause dilated cardiomyopathy with or without skeletal muscular dystrophy. Previous studies have shown abnormally increased extracellular signal-regulated kinase 1/2 activity in hearts of LmnaH222P/H222P mice, a small animal model. Inhibition of this abnormal signaling activity with a mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor has beneficial effects on heart function and survival in these mice. However, such treatment has not been examined relative to any standard of care intervention for dilated cardiomyopathy or heart failure. We therefore examined the effects of an angiotensin II converting enzyme (ACE) inhibitor on left ventricular function in LmnaH222P/H222P mice and assessed if adding a MEK1/2 inhibitor would provide added benefit. MethodsMale LmnaH222P/H222P mice were treated with the ACE inhibitor benazepril, the MEK1/2 inhibitor selumetinib or both. Transthoracic echocardiography was used to measure left ventricular diameters and fractional shortening was calculated. ResultsTreatment of LmnaH222P/H222P mice with either benazepril or selumetinib started at 8weeks of age, before the onset of detectable left ventricular dysfunction, lead to statistically significantly increased fractional shortening compared to placebo at 16weeks of age. There was a trend towards a great value for fractional shortening in the selumetinib-treated mice. When treatment was started at 16weeks of age, after the onset of left ventricular dysfunction, the addition of selumetinib treatment to benazepril lead to a statistically significant increase in left ventricular fractional shortening at 20weeks of age. ConclusionsBoth ACE inhibition and MEK1/2 inhibition have beneficial effects on left ventricular function in LmnaH222P/H222P mice and both drugs together have a synergistic benefit when initiated after the onset of left ventricular dysfunction. These results provide further preclinical rationale for a clinical trial of a MEK1/2 inhibitor in addition to standard of care in patients with dilated cardiomyopathy caused by LMNA mutations.

Isolation of novel bioactive regions from bovine Achilles tendon collagen having angiotensin I-converting enzyme-inhibitory properties

Collagen, a structural biopolymer of the extracellular matrix, is known to conceal several bioactive peptides which, when excised, can display physiological actions including angiotensin II-converting enzyme (ACE) inhibition. ACE is a key protease controlling the blood pressure (BP) by cleaving dipeptides from an inactive propeptide to produce angiotensin II, a potent BP regulator. Natural inhibitors of ACE, though less potent, have the advantage of being biocompatible and non-toxic. This study was undertaken to identify such cryptic regions from bovine Achilles tendon collagen. Bacterial collagenase was used to hydrolyze collagen and the hydrolysate was subjected to separation through ion-exchange column chromatography. Fractions were subjected to ACE inhibition assays and further purified by gel permeation chromatography. Two biologically active cryptic peptides were obtained displaying potent inhibition abilities; D1 and E2. The peptides were in the mass range of 1.5–3.5kDa and the inhibition was found to be competitive. Sequence analysis confirmed a relatively higher % occurrence of amino acids A and N in comparison to collagen and a hydrophobic C-terminal with P as the terminus. Both peptides were found to retain 80% of activity, even after digestive enzyme treatment. IC50 values revealed D1 to be the most potent inhibitor. Docking studies revealed that both peptides were using the C-terminal to interact with ACE-binding site. A comparison with other peptides displaying competitive inhibition hinted at the presence of a unique sequence GX′Y′ where X′ is often P, L, I or A and Y′ often P as the probable C-terminal for effective inhibition.

Renal oxygen content is increased in healthy subjects after angiotensin-converting enzyme inhibition

OBJECTIVE:The association between renal hypoxia and the development of renal injury is well established. However, no adequate method currently exists to non-invasively measure functional changes in renal oxygenation in normal and injured patients.METHOD:R2* quantification was performed using renal blood oxygen level-dependent properties. Five healthy normotensive women (50±5.3 years) underwent magnetic resonance imaging in a 1.5T Signa Excite HDx scanner (GE Healthcare, Waukesha, WI). A multiple fast gradient-echo sequence was used to acquire R2*/T2* images (sixteen echoes from 2.1 ms/slice to 49.6 ms/slice in a single breath hold per location). The images were post-processed to generate R2* maps for quantification. Data were recorded before and at 30 minutes after the oral administration of an angiotensin II-converting enzyme inhibitor (captopril, 25 mg). The results were compared using an ANOVA for repeated measurements (mean ± standard deviation) followed by the Tukey test. ClinicalTrials.gov: NCT01545479.RESULTS:A significant difference (p<0.001) in renal oxygenation (R2*) was observed in the cortex and medulla before and after captopril administration: right kidney, cortex = 11.08±0.56ms, medulla = 17.21±1.47ms and cortex = 10.30±0.44ms, medulla = 16.06±1.74ms, respectively; and left kidney, cortex = 11.79±1.85ms, medulla = 17.03±0.88ms and cortex = 10.89±0.91ms, medulla = 16.43±1.49ms, respectively.CONCLUSIONS:This result suggests that the technique efficiently measured alterations in renal blood oxygenation after angiotensin II-converting enzyme inhibition and that it may provide a new strategy for identifying the early stages of renal disease and perhaps new therapeutic targets.

Recommendations for the treatment of hypertension in the elderly and very elderly: a scotoma within international guidelines

The recommendations of international scientific societies for the treatment of hypertension in the geriatric population are different. Lack of outcome trials, non-standardised terminology as well as differing levels of evidence contribute to the inconsistencies in the guidelines. This review article compares six international guidelines (ESH-ESC 2007/2009, SHG 2009, DHL 2008, CHEP 2010, NICE 2011 and JNC7 2003) as well as the consensus document of the ACCF/AHA 2011 in terms of their recommendations of drug classes, target blood pressure values and the use of combination therapy. Generally, antihypertensive therapy appears to be clinically beneficial in geriatric patients. Target blood pressure values of <140-150/90 mm Hg and <140/90 mm Hg can be used as a general guideline for octogenarians (80-89 yrs) and septuagenarians (70-79 yrs) respectively. While angiotensin-II converting enzyme inhibitors and diuretics appear to be advantageous in treating combined systolic-diastolic hypertension, calcium-channel blockers and diuretics are to be recommended in the management of isolated systolic hypertension. Combination therapy often increases the efficacy of the treatment as well as patient medication adherence. Furthermore, by making the most of drug combination synergy, lower doses may be used resulting in fewer side-effects.

Chemiluminometric determination of captopril in a multi-pumping flow system

In this work, a simple, versatile and fully automated analytical methodology for the chemiluminometric determination of captopril – an angiotensin II-converting-enzyme (ACE) inhibitor – in pharmaceutical formulations, is proposed. The developed methodology was based on the enhancement by captopril of the chemiluminescence emission of tris(2,2′-bipyridyl)ruthenium(II). In sulphuric acid medium tris(2,2′-bipyridyl)ruthenium(II) was oxidized by cerium(IV) and converted into a reactive oxidant specie [Ru(bpy)3]3+, which was subsequently reduced with captopril in order to yield a significant enhancement of the original chemiluminescence emission that was directly related to captopril concentration. The analytical process was implemented by resorting to an automated multi-pumping flow system (MPFS) that enabled the establishment of multiple reaction interfaces, which, in combination with the created pulsed flowing stream assured a fast and reproducible sample/reagent mixing and reaction development essential to guarantee the generation and subsequent measurement of the short-lived species involved in the chemiluminescent process. The developed system employed three solenoid micro-pumps as the only flow manifold active components. These assured the insertion, propelling and commuting of all solutions. The automatic actuation of the solenoid micro-pumps provided an easily programmed, operated and controlled analytical flow system, exhibiting high versatility, efficiency and compactness at a low cost.Under the optimized experimental conditions, the proposed method allowed the determination of captopril for concentrations between 2×10−3 and 1.5×10−1mmolL−1 (r=0.9996, n=6) and a sampling frequency of about 58 determinations per hour, producing 620μL of waste per determination. The results obtained for pharmaceutical formulations were statistically comparable to those provided by the reference procedure with a relative deviation between −2.32 and 1.39%. The possible mechanism of the chemiluminescence reaction was also discussed in this work.