Abstract Angiotensin Converting Enzyme Research Articles

Angiotensin I converting enzyme gene polymorphisms and risk of psychiatric disorders

Angiotensin-converting enzyme (ACE) as an important enzyme in the renin-angiotensin system facilitates biogenesis of the functionally active product angiotensin II from angiotensin I. ACE gene contains a number of functional polymorphisms which modulate activity of the encoded protein. In the current case–control study, we appraised the association between the rs4359 and rs1799752 polymorphisms and risk of bipolar disorder (type I and type II; BPDI and BPDII), schizophrenia (SCZ) and obsessive–compulsive disorder (OCD). The rs4359 was associated with risk of OCD, BPDI and BPDII in co-dominant and dominant models. The rs1799752 was associated with all assessed psychiatric conditions in four inheritance models except for BPDII whose association was not significant in recessive model. The I allele of rs1799752 was associated with OCD (adjusted FDR q-Value = 4.04E-04), SCZ (adjusted FDR q-Value = 6.00E-06), BPDI (adjusted FDR q-Value = 8.40E-03) and BPDII (adjusted FDR q-Value = 6.00E-06). The effective T allele of rs4359 showed a significant association with disease risk for BPDII group. The estimated haplotypes of these polymorphisms have been distributed differently among patients and controls. Taken together, ACE polymorphisms can be regarded as risk factors for a variety of psychiatric disorders.

Effect of rs4646994 polymorphism of angiotensin-converting enzyme on the risk of nonischemic cardiomyopathy.

Background: Angiotensin-converting enzyme (ACE) gene polymorphisms have recently been shown to be associated with risk of developing left ventricular hypertrophy (LVH). However, the results were controversial. We aimed to conduct this meta-analysis to further confirm the association between ACE rs4646994 polymorphism and hypertrophic cardiomyopathy (HCM)/dilated cardiomyopathy (DCM).Methods: PubMed, Embase, the Chinese National Knowledge Information, and Wanfang databases were searched for eligible studies. The Newcastle–Ottawa Scale (NOS) was used to evaluate the quality of included studies. Then we evaluated the association between ACE gene mutation and HCM/DCM by calculating odds ratios (ORs) and 95% confidence intervals (95% CIs). Subgroup analysis was further performed to explore situations in specialized subjects. Sensitivity analysis and publication bias was assessed to confirm the study reliability.Results: There were 13 studies on DCM (2004 cases and 1376 controls) and 16 studies on HCM (2161 controls and 1192 patients). ACE rs4646994 polymorphism was significantly associated with DCM in all genetic models. However, in HCM, four genetic models (allele model, homozygous model, heterozygous model, and dominant model) showed significant association between ACE rs4646994 polymorphism and DCM. In subgroup analysis, we found that ACE rs4646994 polymorphism was significantly associated with DCM/HCM in Asian population. Finally, we also conducted a cumulative meta-analysis, which indicates that the results of our meta-analysis are highly reliable.Conclusion: ACE rs4646994 polymorphism increases the risk of DCM/HCM in Asians, but not in Caucasians. More case–control studies are needed to strengthen our conclusions and to assess the gene–gene and gene–environment interactions between ACE rs4646994 polymorphism and DCM/HCM.

A UPLC-DAD-Based Bio-Screening Assay for the Evaluation of the Angiotensin Converting Enzyme Inhibitory Potential of Plant Extracts and Compounds: Pyrroquinazoline Alkaloids from Adhatoda vasica as a Case Study.

Angiotensin converting enzyme (ACE) plays a crucial role in regulating blood pressure in the human body. Identification of potential ACE inhibitors from medicinal plants supported the idea of repurposing these medicinal plants against hypertension. A method based on ultra-performance liquid chromatography (UPLC) coupled with a diode array detector (DAD) was used for the rapid screening of plant extracts and purified compounds to determine their ACE inhibitory activity. Hippuryl-histidiyl-leucine (HHL) was used as a substrate, which is converted into hippuric acid (HA) by the action of ACE. A calibration curve of the substrate HHL was developed with the linear regression 0.999. The limits of detection and quantification of this method were found to be 0.134 and 0.4061 mM, respectively. Different parameters of ACE inhibitory assay were optimized, including concentration, incubation time and temperature. The ACE inhibition potential of Adhatoda vasica (methanolic-aqueous extract) and its isolated pyrroquinazoline alkaloids, vasicinol (1), vasicine (2) and vasicinone (3) was evaluated. Compounds 1–3 were characterized by various spectroscopic techniques. The IC50 values of vasicinol (1), vasicine (2) and vasicinone (3) were found to be 6.45, 2.60 and 13.49 mM, respectively. Molecular docking studies of compounds 1–3 were also performed. Among these compounds, vasicinol (1) binds as effectively as captopril, a standard drug of ACE inhibition.

Aspecte clinice privind profilul de siguranță al inhibitorilor enzimei de conversie a angiotensinei

Angiotensin converting enzyme (ACE) inhibitors represent a therapeutic class largely used in clinical practice for about 40 years and extensively studied globally. They are mainly recommended for treatment of hypertension and heart failure with reduced ejection fraction, but were also effective in patients with myocardial infarction, stroke and diabetes, proving significant reduction of cardiovascular morbidity and mortality. Besides their undeniable benefits, proven by clinical practice and epidemiological studies, the use of these drugs involves some side effects, the most common being persistent cough and recurrent angioedema. The mechanism of these side effects is the increase in plasma and pulmonary bradykinin levels, as consequence of blocking the angiotensin converting enzyme. ACE-induced cough occurs relatively frequently, usually within the first months of treatment, but sometimes later, leading to multiple investigations and different specialist consultations. ACE-induced angioedema has a lower frequency, is influenced by some individual factors and can occur at any time during the treatment with IECA, making difficult to confirm the diagnosis. The aim of our paper is to present the main current clinical aspects regarding the safety profile of ACE inhibitors, the peculiarities and difficulties of diagnosis, some individual risk factors and the main recommendations for therapeutic approach.

Abstract MP43: Knockout Of ACE-N Facilitates Improved Cardiac Function After Myocardial Infarction

Angiotensin-converting enzyme (ACE) hydrolyzes N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) into inactive fragments through its N-terminal domain (ACE-N). We reported that cardioprotective effects of ACE inhibitor in angiotensin II-induced hypertension were partially mediated through increased Ac-SDKP bioavailability. Whether increased endogenous Ac-SDKP by knocking out ACE-N leads to improved cardiac function in myocardial infarction (MI) is unknown. Wild-type (WT) and ACE-N knockout (ACE-N -/- ) mice were subjected to MI induced by ligating the left anterior descending artery and treated with either vehicle or Ac-SDKP (1.6 mg/kg/day, s.c.) for 5 weeks. Echocardiography was performed on awake mice at the end of experiment and left ventricles (LV) were harvested for histology and molecular biology studies. ACE-N-/- mice showed increased plasma Ac-SDKP level in Sham or MI group compared to WT. Exogenous Ac-SDKP further increased Ac-SDKP level in both WT and ACE-N-/-. SF and EF were significantly decreased in both WT and ACE-N-/- mice post-MI, . Exogenous Ac-SDKP further increased EF and SF post-MI only in WT, but not in ACE-N-/- mice. Sarcoendoplasmic reticulum calcium transport ATPase 2 (SERCA2), a marker of cardiac calcium homeostatsis, significantly decreased in WT post-MI was rescued with Ac-SDKP, whereas ACE-N-/- mice displayed less reduction in SERCA2 expression. These results demonstrate that gene deletion of ACE-N improves cardiac function in mice post-MI, which was associated with increased Ac-SDKP level and minimally reduced expression of SERCA2.Therefore,this study illustrates that endogenous Ac-SDKP results in cardioprotective role in MI.

Serum INHB levels and ACE gene I/D polymorphism with increased risk for unexplained infertility.

Angiotensin converting enzyme (ACE) has a significant role in the angiogenesis of ovarian endothelium and the resumption of meiosis and folicular growth. However, there is no any study concerning ACE polymorphism and unexplained infertility (UI). The main aim of this study is that both identify ACE polymorphism and measure the serum ACE, anti-Mullerian hormone (AMH) and inhibin-B (INHB) levels in UI patients and controls in Turkish population. Forty-seven UI patients and 41 controls were involved in this study. To determine the ACE polymorphisms, DNA isolation and PCR were performed. Then, serum ACE, AMH and INHB levels were measured spectrophotometrically. Patients with UI had significantly higher serum INHB levels compared with controls (P < 0.05). Serum ACE levels were decreased, compared to controls; however, the decrease was not significant. Serum AMH levels did not significantly differ from controls. When the relationship was analysed between ACE insertion/deletion (I/D) polymorphism and infertility risk, and ID genotype was chosen as reference, it was found to be 2.33 times more risk of UI than the women have DD genotype [DD versus ID: odds ratio = 2.33, 95% confidence interval (0.88-6.19); P = 0.086]. This finding indicates that DD genotype may be high risk for UI. Further studies are warranted to confirm this finding, especially with a larger population.

Renin-angiotensin system is involved in embryonic emergence of hematopoietic stem/progenitor cells.

Angiotensin-converting enzyme (ACE), a key element of the renin-angiotensin system (RAS), has recently been identified as a new marker of both adult and embryonic human hematopoietic stem/progenitor cells (HSPCs). However, whether a full renin-angiotensin pathway is locally present during the hematopoietic emergence is still an open question. In the present study, we show that this enzyme is expressed by hematopoietic progenitors in the developing mouse embryo. Furthermore, ACE and the other elements of RAS-namely angiotensinogen, renin, and angiotensin II type 1 (AT1) and type 2 (AT2) receptors-are expressed in the paraaortic splanchnopleura (P-Sp) and in its derivative, the aorta-gonad-mesonephros region, both in human and mouse embryos. Their localization is compatible with the existence of a local autocrine and/or paracrine RAS in these hemogenic sites. in vitro perturbation of the RAS by administration of a specific AT1 receptor antagonist inhibits almost totally the generation of blood CD45-positive cells from dissected P-Sp, implying that angiotensin II signaling is necessary for the emergence of hematopoietic cells. Conversely, addition of exogenous angiotensin II peptide stimulates hematopoiesis in culture, with an increase in the number of immature c-Kit+ CD41+ CD31+ CD45+ hematopoietic progenitors, compared to the control. These results highlight a novel role of local-RAS during embryogenesis, suggesting that angiotensin II, via activation of AT1 receptor, promotes the emergence of undifferentiated hematopoietic progenitors.

ACE2 and ACE: structure-based insights into mechanism, regulation and receptor recognition by SARS-CoV.

Angiotensin converting enzyme (ACE) is well-known for its role in blood pressure regulation via the renin–angiotensin aldosterone system (RAAS) but also functions in fertility, immunity, haematopoiesis and diseases such as obesity, fibrosis and Alzheimer’s dementia. Like ACE, the human homologue ACE2 is also involved in blood pressure regulation and cleaves a range of substrates involved in different physiological processes. Importantly, it is the functional receptor for severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 responsible for the 2020, coronavirus infectious disease 2019 (COVID-19) pandemic. Understanding the interaction between SARS-CoV-2 and ACE2 is crucial for the design of therapies to combat this disease. This review provides a comparative analysis of methodologies and findings to describe how structural biology techniques like X-ray crystallography and cryo-electron microscopy have enabled remarkable discoveries into the structure–function relationship of ACE and ACE2. This, in turn, has enabled the development of ACE inhibitors for the treatment of cardiovascular disease and candidate therapies for the treatment of COVID-19. However, despite these advances the function of ACE homologues in non-human organisms is not yet fully understood. ACE homologues have been discovered in the tissues, body fluids and venom of species from diverse lineages and are known to have important functions in fertility, envenoming and insect–host defence mechanisms. We, therefore, further highlight the need for structural insight into insect and venom ACE homologues for the potential development of novel anti-venoms and insecticides.

Abstract MP25: Expression Of Urinary Somatic And Soluble N-domain Isoforms Of Angiotensin Converting Enzyme And Association With Different Nutritional Status And Cardiovascular Risk Profile

Angiotensin converting enzyme (ACE) plays a dominant role in renal and cardiovascular diseases, obesity and diabetes. The somatic ACE (130-190 kDa) is composed of two homologous N- and C- domains. Two soluble N-domain isoforms have been described in human urine with 65 and 90KDa. Studies have supported that N-domain ACE with 90KDa is a biomarker for hypertension, pre-eclampsia and inflammation. We analyzed the expression of somatic and soluble N-domain ACE isoforms in urine of children and adolescents with different nutritional status and cardiovascular risk profile. The volunteers aged from 6 to 19 years were classified into four groups according to their BMI percentile; underweight (n=51), normal weight (n = 53), overweight (n=53) and obese (n=49). Waist-height-ratio (WHtR) was used to assess cardiovascular risk profile dividing the participants into normal risk (n=105) and high risk (n=101). The urines were concentrated 10-fold and dialyzed with Tris-HCl pH 8 and pure water. Then, we performed western blot analysis using 50μg of lyophilized urinary protein, using the ACE polyclonal antibody Y1. Protein detection was performed by chemiluminescent and analysis in Image Lab software utilizing total protein stain for normalization. ACE expression is augmented in obese children when compared with normal weight children ( 0.09 vs 0.53 arbitrary units, p=0,04 ). The higher cardiovascular risk group also presented increased expression of ACE ( 0.27 vs 0.09 arbitrary units, p=0.046 ). The 90KDa N-domain isoform is frequently found in the high cardiovascular risk children ( p= 0.02 ). According to Spearman correlation test, the expression of 90 kDa N-domain ACE correlates positively with waist circumference, WHtR, BMI percentile and Z-score of BMI. Increased ACE expression in obese children contributes to higher cardiovascular risk once this enzyme biosynthesizes Angiotensin II which promotes blood pressure increase, sympathetic nervous system activation and release of glucocorticoids from adrenal gland. ACE expression is also augmented in children with high cardiovascular risk. Presence of 90 KDa N-domain ACE in urine of children and adolescents is a biomarker of poor prognostic for cardiovascular disease in childhood obesity.

1670-P: Enalapril Maleate, Angiotensin-Converting Enzyme Inhibitor, Suppresses the Expression of the MHC Molecules in Mucosal Cells of the Small Intestine Leading to the Delayed Onset of Autoimmune Type 1 Diabetes Mellitus in NOD Mice

Angiotensin-converting enzyme (ACE) exists in the kidney, lung and small intestine of the NOD mouse (autoimmune type 1 diabetes animal model). ACE changes Angiotensin I to Angiotensin II. ACE exists in the small intestinal epithelial cells and villi, and digests the protein antigen molecules in the small intestine. ACE plays an important role in the antigen presenting process in the mucosal immune system of the duodenum and jejunum. To examine if ACE has a role in the development of type 1 diabetes of the NOD mouse, ACE Inhibitors, enalapril maleate (EM) or captopril (CA) was dissolved in a drinking water at the concentration of 12.5μg/ml and given daily to 28-day-old NOD mice ad libitum (89 females and 70 males in CA, 72 and 52 in EM, 120 and 87 in water control group, respectively). The animals were screened for the development of diabetes twice a week for 7 months and subjected to the Life Table analysis. The incidence of diabetes in our NOD/Kmc colony is 83% in females and 40% in males at 210 days of age. The EM-treated NOD mice showed a significant delay of the onset of diabetes at 120 days of age in comparison with the controls (25% vs. 45% in females, P=0.002; 0% vs. 8% in males, P=0.037). The CA treatment was ineffective to delay the onset of diabetes. The histological examination of the pancreata showed that the EM-treated females had more islets without lymphocytic infiltration than the water-control females (mean number of undamaged islets±SD: 11.1±8.5 in EM vs. 1.9±2.5 in Control, P=0.009). The undamaged islets weighed 0.772±0.383 in EM and 0.441±0.386 in water-control (mg: mean±SE). The mRNA expression of MHC K and A genes was suppressed in the duodenum and jejunum of the NOD mice by EM- or CA-water for 14 days. Flow cytometric analysis showed suppression of the MHC K and I-A expression in the pancreatic lymphocytes of the EM- and CA-treated mice in comparison with the control mice. Disclosure M. Hattori: None. A. Ueda: None. R. Katoh: None. M. Hirai: None. A. Noda: None. K. Mayanagi: None. Y. Furuichi: None. K. Hattori: None. T. Lund: None. K. Kobayashi: None. Y. Nakamura: None.

Angiotensin-Converting Enzyme Inhibitor (ACEI) suppresses the expression of the MHC molecules in mucosal cells of the small intestine leading to the delayed onset of autoimmune type 1 diabetes mellitus in NOD mice

Abstract Angiotensin-converting enzyme (ACE) exists in the kidney, lung and small intestine of the NOD mouse (autoimmune type 1 diabetes animal model). ACE changes Angiotensin I to Angiotensin II. ACE exists in the small intestinal epithelial cells and villi, and digests the protein antigen molecules in the small intestine. ACE plays an important role in the antigen presenting process in the mucosal immune system of the duodenum and jejunum. To examine the role of ACE in the development of type 1 diabetes of the NOD mouse, ACE-Inhibitors (ACEI): captopril (CA) or enalapril maleate (EM) was dissolved in a drinking water at the concentration of 12.5mg/ml and given daily to 28-day-old NOD females and males ad libitum (89 females and 70 males in CA, 72 and 52 in EM, 120 and 87 in water control group, respectively). The animals were screened for the development of diabetes twice a week for 7 months and subjected to the Life Table analysis. The incidence of diabetes in our NOD/Kmc colony is 83% in females and 40% in males at 210 days of age. The EM-treated NOD mice showed a significant delay of the onset of diabetes at 120 days of age in comparison with the controls (25% vs. 45% in females, p=0.002; 0% vs. 8% in males, p=0.037). The CA treatment was ineffective to delay the onset of diabetes. The histopathological examination of the pancreata showed that the EM-treated females had more islets without lymphocytic infiltration than the CA-treated or the water-control females. The mRNA expression of MHC K and A genes was suppressed in the duodenum and jejunum of the NOD mice by EM- or CA-water for 14 days. Flow cytometric analysis showed suppression of the MHC K and I-A expression in the pancreatic lymphocytes of the EM- and CA-treated mice in comparison with the control mice.

Structural basis for the C-domain-selective angiotensin-converting enzyme inhibition by bradykinin-potentiating peptide b (BPPb).

Angiotensin-converting enzyme (ACE) is a zinc metalloprotease best known for its role in blood pressure regulation. ACE consists of two homologous catalytic domains, the N- and C-domain, that display distinct but overlapping catalytic functions in vivo owing to subtle differences in substrate specificity. While current generation ACE inhibitors target both ACE domains, domain-selective ACE inhibitors may be clinically advantageous, either reducing side effects or having utility in new indications. Here, we used site-directed mutagenesis, an ACE chimera and X-ray crystallography to unveil the molecular basis for C-domain-selective ACE inhibition by the bradykinin-potentiating peptide b (BPPb), naturally present in Brazilian pit viper venom. We present the BPPb N-domain structure in comparison with the previously reported BPPb C-domain structure and highlight key differences in peptide interactions with the S4 to S9 subsites. This suggests the involvement of these subsites in conferring C-domain-selective BPPb binding, in agreement with the mutagenesis results where unique residues governing differences in active site exposure, lid structure and dynamics between the two domains were the major drivers for C-domain-selective BPPb binding. Mere disruption of BPPb interactions with unique S2 and S4 subsite residues, which synergistically assist in BPPb binding, was insufficient to abolish C-domain selectivity. The combination of unique S9-S4 and S2' subsite C-domain residues was required for the favourable entry, orientation and thus, selective binding of the peptide. This emphasizes the need to consider factors other than direct protein-inhibitor interactions to guide the design of domain-selective ACE inhibitors, especially in the case of larger peptides.

Abstract 035: Increasing Renal AcSDKP by Eliminating the ACE N-Domain Blocks Renal Inflammation and Sodium Retention During Diabetic Nephropathy

Angiotensin-converting enzyme (ACE) plays a key role in renal inflammation and sodium retention associated with diabetic nephropathy. Although most effects of ACE have been classically related to angiotensin (Ang) II synthesis, studies highlight an Ang II-independent role of ACE in inflammation. Indeed, ACE has two catalytic domains, the N- and C-domains, that can process a wide diversity of substrates besides Ang I. Here, we study the relative contributions of ACE domains to renal inflammation and sodium retention during diabetic nephropathy. Diabetes was induced with streptozotocin in wild-type (WT) mice and mice lacking either a functional ACE N-domain (NKO) or C-domain (CKO) (n=5-8). After 6 months of diabetes, we evaluated the natriuretic response to volume expansion. For this, mice were injected with 0.9% NaCl equivalent to 10% of their body weight. After 5 hours, diabetic NKO mice excreted 30% more urinary sodium in response to the saline challenge compared to diabetic WT or CKO mice ( P &lt;0.05). This enhanced natriuretic response was associated with a 47% reduction ( P &lt;0.05) of renal epithelial sodium channel (ENaC) cleaved (active) α and γ subunits. Further, diabetic NKO displayed lower levels of renal fibrosis (46% reduction, P &lt;0.05), IL-1β (56% reduction, P &lt;0.05), TNFα (50% reduction, P &lt;0.05) and albuminuria (53% reduction, P &lt;0.01) compared to WT and CKO diabetic mice. This protective phenotype was not associated with changes in renal Ang II levels (WT: 237 ± 73; NKO: 283 ± 53 CKO: 245 ± 39 fmol/g kidney, P =NS). We next evaluated whether the anti-inflammatory tetrapeptide N-acetyl-seryl-asparyl-lysyl-proline (AcSDKP), an ACE N-domain specific substrate, mediates the protective phenotype of NKO. For this, diabetic mice were treated with the prolyl oligopeptidase inhibitor, S17092 (10 mg/kg, IP), that prevents the synthesis of AcSDKP. In diabetic NKO mice receiving S17092, sodium excretion in response to a saline challenge, ENaC α and γ subunit cleavage, renal inflammation and renal injury were indistinguishable from equally treated diabetic WT mice. In summary, these data indicate that increasing AcSDKP by blocking the ACE N-domain improves sodium handling and ameliorates diabetic kidney disease independently of intrarenal Ang II regulation.

The Evaluation of Angiotensin-Converting Enzyme Inhibitors in Renal Elimination with Selected Molecular Descriptors

Abstract Angiotensin-converting enzyme (ACE) inhibitors modulate the function of the renin-angiotensin-aldosterone system, and they are commonly prescribed antihypertensive drugs especially in patients with renal failure. In this study, the relationships between several molecular properties of eight ACE inhibitors (enalapril, quinapril, fosinopril, ramipril, benazepril, perindopril, moexipril, trandolapril) and their renal elimination data, from relevant literature, were investigated. The ’molecular descriptors of the ACE inhibitors, which included aqueous solubility data (logS); an electronic descriptor, polar surface area (PSA);, a constitutional parameter, molecular mass (Mr); and a geometric descriptor, volume value (Vol), as well as lipophilicity descriptors (logP values), were calculated using different software packages. Simple linear regression analysis showed the best correlation between renal elimination data and lipophilicity descriptor AClogP values (R2 = 0.5742). In the next stage of the study, multiple linear regression was applied to assess a higher correlation between the ACE inhibitors’ renal elimination data and lipophilicity, AClogP, with one additional descriptor as an independent variable. Good correlations were established between renal elimination data from the literature and the AClogP lipophilicity descriptor using the constitutional parameter (molecular mass (R2 = 0.7425)) or the geometric descriptor (volume value (R2 = 0.7224)) as an independent variable. The application of computed molecular descriptors in evaluating drug elimination is of great importance in drug research.

Association of I/D angiotensin-converting enzyme genotype with erythropoietin stimulation in kidney failure

Angiotensin-converting enzyme (ACE)-gene polymorphism is a possible predisposing factor of erythropoietin response under hypoxic conditions. However, it is not completely clear whether the ACE insertion/deletion (I/D) genotype has an impact on anemia in patients with permanent kidney failure. A 9-month prospective trial was conducted on 53 patients on hemodialysis aimed at determining the beneficial effect of oral vs intravenous iron in anemia management with recombinant human erythropoietin (rHuEpo), and identifying a possible association of the ACE gene I/D polymorphism with the response to rHuEpo. Patients were randomly allocated to receive 50-100 mg daily of ferrous gluconate orally (N=26) or intravenously every two weeks (N=27), together with rHuEpo-beta (200 IU/kg) subcutaneously, to achieve a hemoglobin increase to 105 g/L; subsequently the rHuEpo dose was adjusted at one or two week intervals. In 34 patients who regularly received ACE-inhibitor (ACEi) medication, genotyping for ACE-gene I/D polymorphism was performed using PCR, gel analysis and appropriate restriction digestion. After prolonged rHuEpo treatment, 24.5% of patients attained the targeted 9th-month hemoglobin concentration (105 g/L). Of these, 6/26 of patients received elemental iron orally and 7/27 received it intravenously. We observed an association between homozygous DD (deletion) of the ACE gene and a remarkable early increase in blood hemoglobin (p=0.028), erythrocyte count (p=0.020) and hematocrit (p=0.043) after reduction of the dose of rHuEpo (F=3.95; p=0.029), irrespective of the iron repletion mode (p=0.960). This is the first report on DD genotype as a linkage marker for the optimization of rHuEpo dose for anemia management in hemodialysis patients.

The influence of angiotensin-converting enzyme gene ID polymorphism on human physical fitness performance in European and other populations

Angiotensin-converting enzyme (ACE) is a component of the circulating renin–angiotensin system, which influences circulatory homeostasis through the degradation of vasodilator kinins and the generation of vasopressor angiotensin II. Various phenotypic characteristics such as diseases and human performances could be associated with genetic polymorphisms within the ACE gene. To date, one of the most well-studied genetic polymorphisms that has been shown to be associated with athletic performance is that of the ACE gene. Previous studies investigating the influences of polymorphisms and various phenotypic characteristics have produced inconsistent findings due to inter-ethnic variations in the distribution of the different ACE alleles. For example, some studies showed that the I allele was associated with fatigue resistance in skeletal muscle and endurance performance while the D allele had been associated with power or sprint performance. Nevertheless, controversy still exists regarding the above conclusion as related studies reported that the I allele was associated with a better power or sprint performance rather than with athletic endurance abilities. This article discusses the inter-ethnic variations of the distribution of the different ACE alleles in several ethnic groups such as in European, African, American, and Asian populations. Additionally, the influences of the ACE ID polymorphism on human physical fitness performances in European and other populations are discussed.

Abstract P316: Angiotensin-(1-7) Contributes to the Insulin-sensitizing Effects of Renin-angiotensin System Blockade in High Fat Fed Mice

Angiotensin-converting enzyme (ACE) inhibitors reduce body weight, lower blood pressure, and improve glucose homeostasis in animal models of the cardiometabolic syndrome. These effects are generally attributed to a reduction in angiotensin (Ang) II formation; however, these therapies also increase circulating levels of Ang-(1-7), a peptide with direct anti-hypertensive and insulin-sensitizing effects. In this study, it was hypothesized that endogenous Ang-(1-7) generation contributes to the beneficial cardiometabolic effects of ACE inhibition. To test this hypothesis, diet-induced obesity was produced in adult male C57BL/6J mice by placing them on a 60% high fat diet for 11 weeks. The Ang-(1-7) mas receptor antagonist A779 (400 ng/kg/min) or saline was given after 8 weeks of the high fat diet by subcutaneous osmotic mini-pumps. Immediately following mini-pump implantation, mice received water containing the ACE inhibitor captopril (50 mg/L) or plain tap water. Hyperinsulinemic (4 mU/kg/min) euglycemic clamps were performed in conscious, unrestrained vehicle (n=6), captopril (n=6), or captopril plus A779 (n=13) mice at the end of the 3-week treatment period. Blood pressure was measured via an indwelling carotid artery catheter connected to a transducer on the morning of the clamp. Captopril reduced body weight (28±2 vs. 41±2 g vehicle; p=0.001), lowered blood pressure (systolic: 109±6 vs.144±7 mmHg vehicle; p=0.003), and improved whole-body insulin sensitivity (steady-state glucose infusion rate: 31±4 vs. 16±2 mg/kg/min; p=0.008) in high-fat fed mice. Mas receptor antagonism with A779 attenuated the improvement in insulin sensitivity produced by captopril in high fat fed mice (23±2 mg/kg/min; p=0.042). There was no effect of A779 on the weight loss (32±2 g) or blood pressure lowering effects (111±7 mmHg) of captopril. These findings suggest that the improvement in insulin sensitivity produced by ACE inhibition is at least partly mediated by Ang-(1-7) pathways, and provide new insight into potential mechanisms involved in renin-angiotensin system blockade.

Isolation and Characterization of a New Angiotensin-converting Enzyme Inhibitory Peptide from Heterobronchus bidorsalis

Angiotensin converting enzyme (ACE) plays an important physiological role in the regulation of blood pressure by converting angiotensin I to angiotensin II, a potent vasoconstrictor; hence, its inhibition is a major target in the prevention and treatment of hypertension. In this study a novel ACE inhibitory peptide from Heterobronchus bidorsalis (cat fish) was isolated, purified and characterized. The peptide was purified by ammonium sulphate precipitation, dialysis and gel filtration chromatography (sephadex G-50). The amino acid sequence of the seventeen amino acid peptide was found to be KHRDTSEPGACVMILYF with a final inhibitory activity of 0.07 μmol/ml and a purification fold of 2.93 having a percentage yield of 34 %. The peptide had an optimum temperature and pH of 37°C and 8.3, respectively. The ACE inhibitory activity of the peptide reduced in the presence of sodium, calcium, magnesium, and potassium ions, while EDTA increased it when compared to the control. Treatment with trypsin also increased the inhibitory activity of the peptide. The peptide exhibited a non-competitive-type of inhibition, indicating that it binds to a site other than the active site. In conclusion, peptides from H. bidorsalis may be promising ACE inhibitors that can serve as nutraceuticals or drugs for blood pressure regulation in hypertensive patients.

Association between ACE polymorphism, cognitive phenotype and APOE E4 allele in a Tunisian population with Alzheimer disease.

Angiotensin-converting enzyme (ACE) has shown altered activity in patients with neurological diseases. An insertion/deletion (I/D) polymorphism of the ACE gene encoding angiotensin-converting enzyme has been reported to be associated with the risk for Alzheimer's disease (AD), and is generally considered to be a disorder primarily affecting memory. We conducted a case-control study in a sample composed of 85 sporadic AD patients and 90 age- and sex-matched controls to investigate the possible effect of the polymorphism and cognitive profile. Our data revealed an association between the ACE polymorphism and AD risk. There was a significant difference in the ACE allele or genotype frequencies between cases and controls. The D/D genotype showed an increased risk for AD and in the amnestic group and the effect was independent on ApoE genotypes.

Changes in Some Quality Properties of Kefir during Storage and Inhibition Effect of Water Soluble Extracts on Angiotensin-I Converting Enzyme Purified by Human Plasma

Abstract Angiotensin converting enzyme (ACE)-inhibitory activity in water soluble extracts (WSEs) of kefir was investigated. Kefir was produced traditionally using kefir grains and stored at refrigerated temperature for 20 days. During storage period (on 1, 5, 10, 15 and 20 days) in vitro ACE-inhibitory activity in WSEs was determined. ACE was purified from human plasma to determine kinetic parameters. Purified ACE had a specific activity of 20.75 EU.mg−1, a yield of 16.6% with a factor of 22100. The inhibition effects of kefir on ACE increased at 15 storage days than other storage days. Some microbiological and physicochemical characteristics of kefir were also studied. Counts of presumptive LAB on M-17 and presumptive LAB on MRS in the kefir were about 108 CFU.ml−1 throughout the storage period. Yeast counts were lower than lactic acid bacteria counts and the average of the counts was approximately 106 log CFU.ml−1. Storage period had a significant effect (P &lt; 0.05) on titratable acidity and pH values. On the contrary, it had no significant effect (P &gt; 0.05) on viscosity and serum separation values of kefir.