Aortic atherosclerosis in diabetes mellitus is associated with an insertion/deletion polymorphism in the angiotensin I-converting enzyme gene. No relation between the polymorphism and aortic collagen content

Triterpenoids from the roots of Sanguisorba tenuifolia var. Alba

The ethyl acetate soluble fraction from the roots of Sanguisorba tenuifolia was found to have a hypoglucemic effect in alloxan-induced diabetic rats. Two new triterpenoids, identified as 2-oxo-3β,19α-dihydroxyolean-12-en-28-oic acid β-D-gluco-pyranosyl ester (1) and 2α,19α-dihydroxy-3-oxo-12-ursen-28-oic acid β-D-glucopyranosyl ester (4) were isolated from this fraction, along with thirteen known triterpenoids. Their structures were elucidated by chemical and spectroscopic methods. All these compounds demonstrated inhibitory activities against α-glucosidase with IC₅₀ values in the 0.62-3.62 mM range.

Angiotensin converting enzyme DD genotype not associated with increased risk of coronary artery disease in the Iranian population

The coronary artery disease (CAD) is of the main causes of heart failure and there is evidence supporting the association of angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and the susceptibility to CAD. Therefore, the relevance of ACE polymorphism for CAD was determined in the Iranian population. 487 age-matched individuals including 224 patients with >50% angiographically established coronary stenosis and 263 healthy subjects genotyped for ACE gene I/D polymorphism by a standard method. Paraclinical characteristics including lipid profile were also determined for both groups. While the systolic (p<0.0001) and diastolic (p<0.0001) blood pressure, serum cholesterol (p<0.005) and LDL-C (p<0.05) were significantly increased in CAD patients, our results show that there was no increased risk of CAD in association with DD genotype in Iranian population. Allele frequencies were also similar in both groups. Although, we found a significant difference in ID (p<0.005) and II (p<0.05) genotype between patients and healthy subjects. The present study showed that DD genotype does not increase the CAD susceptibility in the studied Iranian population and may not be as a risk factor. Therefore, further studies together with the other polymorphisms of ACE gene may be required to determine the relation between cardiovascular disease susceptibility and ACE genetic variations in Iranian population.

Early sign of atherosclerosis in slow coronary flow and relationship with angiotensin-converting enzyme I/D polymorphism

Increase in carotid artery intima-media thickness (IMT) is an early sign of atherosclerosis. Slow coronary flow (SCF) is characterized by delay of opacification of coronary arteries in coronary angiography in the absence of any evident obstructive lesion, but its etiopathogenesis remains unclear. Genes that regulate the renin angiotensin system also play a role in developing cardiovascular system disorders. The presence of deletion (D) allele in angiotensin converting enzyme (ACE) gene polymorphism is associated with coronary artery disease. The aim of this study was to investigate the carotid artery IMT measurement, as an early sign of atherosclerosis, in patients with SCF and without SCF and also to assess the effect of the renin-angiotensin gene system on carotid IMT. Forty-four patients with angiographically proven SCF and 44 cases with normal coronary flow (NCF) pattern with similar risk profile were enrolled in the study. Coronary flow patterns of the cases were determined by thrombolysis in myocardial infarction (TIMI) frame count method. Intima-media thickness was measured by recording ultrasonographic images of both the left and right common carotid artery with a 12-MHz linear array transducer. ACE I/D polymorphism and Angiotensin II tip 1 receptor (AT1R) A/C gene polymorphism were determined by polymerase chain reaction (PCR) amplification. Demographic characteristics and coronary artery disease risk factors of SCF and NCF groups were similar. Mean TIMI frame count and carotid IMT (mm) were significantly higher in the SCF group than controls (45.9 +/- 12 vs 23.3 +/- 3.7, P = 0.0001; 0.75 +/- 0.08 vs 0.69 +/- 0.06, P = 0.0001, respectively). Mean TIMI frame count was positively correlated with IMT of carotid artery in correlation analysis (r = 0.45, P = 0.0001). When analyzed in regard to ACE genotype in all subjects, IMT values were statistically different (0.78 +/- 0.06 for DD genotype, 0.72 +/- 0.05 for ID genotype, and 0.64 +/- 0.06 for II genotype, P = 0.0001). This difference remained significant in subgroup analyses for each genotype. No association could be observed between the AT1R A/C(1166) polymorphism and IMT of carotid artery measurement (P > 0.05). Lack of association was still observed with analysis carried out when genotype effect was assumed to be inherited as additive (CC versus AA versus AC) or dominant (AA versus AC+CC). Increased IMT in patients with SCF shows that subclinical atherosclerosis may play role in this phenomenon. This increase was most marked in the presence of D allele of ACE genotype, which is associated with vascular hypertrophy.

Combination of multiple genetic risk factors is synergistically associated with carotid atherosclerosis in Japanese subjects with type 2 diabetes

OBJECTIVE

Several genetic risk factors, such as single nucleotide polymorphisms (SNPs), in candidate genes have been reported to be responsible for intima-media thickness (IMT), which is one of the surrogate end points of cardiovascular events. However, the synergistic effects of SNPs have not been evaluated in detail.

RESEARCH DESIGN AND METHODS

We measured the average IMT of the common and internal carotid artery in Japanese type 2 diabetic patients (n = 690) (>50 years old) using ultrasonography. We also determined their genotypes regarding 106 SNPs in candidate genes responsible for cardiovascular diseases. Among the 106 SNPs, we selected 40 common (frequency of minor allele >/=10%) SNPs. We compared the average IMT of subjects with and without any pairs of four genotypes selected from the 40 common SNPs.

RESULTS

The combination of methylen-tetrahydrofolate reductase 677 TT genotype and lymphotoxin-alpha (LTA) 252 GG genotype and that of ACE DD genotype and LTA 252 GG genotype were evaluated as responsible for a statistically significant (P = 2.7 x 10(-9) and 3.5 x 10(-6), respectively) increase in average IMT (mean [+/-SD] 1.54 +/- 0.60 and 1.43 +/- 0.58 mm, respectively) compared with those of the subjects without these combinations (1.04 +/- 0.34 and 1.04 +/- 0.34 mm, respectively). No single genotype was shown to be responsible for the statistically significant difference in average IMT after Bonferroni's multiple comparison procedure.

CONCLUSIONS

The present analysis demonstrates an approach to evaluate combinations of multiple genetic risk factors that are synergistically associated with carotid atherosclerosis.

ACEPolymorphisms

Angiotensin converting enzyme (ACE) plays an essential role in two physiological systems, one leading to the production of angiotensin II and the other to the degradation of bradykinin. The wide distribution and multifunctional properties of these peptides suggest that ACE could be involved in various pathophysiological conditions. The discovery that ACE levels are under genetic control ushered in a new era of investigation; most studies focused on an insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene as a marker for a functional polymorphism. Recently, many single nucleotide polymorphisms were detected in the gene and the search for the locations of functional polymorphisms became a topic of extensive investigation. Nevertheless, association studies on the I/D polymorphism and clinical outcomes continued, mostly with conflicting results. This article reviews the current state of knowledge regarding ACE polymorphisms and suggests that a functional polymorphism is most likely located between intron 18 and the 3' UTR. The potential existence of another functional polymorphism in the 5' UTR, however, cannot be excluded. This review also presents an overview of ACE function in different pathophysiological systems, and summarizes previous reports on ACE and clinical outcomes. Although findings on the I/D polymorphism and disorders like diabetic nephropathy and Alzheimer disease can be considered conclusive, reports on most of the cardiovascular phenotypes are still controversial. Genotypic and phenotypic misclassifications, insufficient power in some studies, and the presence of interaction with other genes or environmental factors are possible explanations for the contradictory findings.

Frequency of angiotensin-converting enzyme gene polymorphism in Turkish type 2 diabetic patients

We aimed to investigate the angiotensin-converting enzyme (ACE) gene polymorphism, ACE activity and their associations with diabetic complications in Turkish patients with type 2 diabetes mellitus. A total of 143 patients and 133 controls were screened for ACE gene I/D polymorphism by using polymerase chain reaction. Serum ACE activities were determined spectrophotometrically. There was no significant difference in the distribution of ACE I/D genotypes between patients and controls. The patients with DD genotype had a higher ACE activity than those with ID and II. Hypertensive diabetic patients with DD genotype had higher ACE activities than those with ID and II. There was no significant difference in the distribution of ACE I/D genotypes between patients with and without nephropathy, retinopathy and hypertension except for patients with and without neuropathy. In patients with DD genotype, creatinine clearance correlated with duration of diabetes. The grade of retinopathy was correlated with duration of diabetes in DD and ID genotypes. The highest ACE activity was measured in hypertensive diabetics with DD genotype. ID genotype was suggested to be a risk factor and II was suggested to be protective for diabetic neuropathy. The DD and ID genotypes might be a predictor for the development of retinopathy in relation to duration of diabetes.

Abdominal Aortic Aneurysm in Normotensive Patients: Association with Angiotensin-converting Enzyme Gene Polymorphism

OBJECTIVE AND DESIGN

to assess if deletion of the angiotensin-converting enzyme (ACE) gene is a risk factor for abdominal aortic aneurysms (AAAs) in normotensive patients.

MATERIALS AND METHODS

ACE gene polymorphism was examined by polymerase chain reaction in 124 subjects with AAA and in 112 control subjects. AAA normotensive patients (group A, n=56) were compared to normotensive control subjects (group B, n =112) and to AAA hypertensive patients (group C, n =68). All subjects enrolled in this study were Caucasian and from central and southern Italy.

RESULTS

the distribution of ACE genotypes was: normotensive patients with AAAs (group A): 3 II, 14 ID, 39 DD; normotensive control subjects (group B): 36 II, 48 ID, 28 DD; hypertensive patients with AAAs (group C): 14 II, 32 ID, 22 DD. The DD genotype was more common in group A than in control groups (A vs B p<0.001; A vs C p <0.001). The ID genotype was more common in group A as well (A vs B p <0.05; A vs C p <0.005).

CONCLUSIONS

our data suggest a role for ACE I/D gene polymorphism in the pathogenesis of AAA in normotensive patients.

Insertion/deletion polymorphism of the angiotensin I-converting enzyme gene is associated with coronary artery plaque calcification as assessed by intravascular ultrasound

OBJECTIVES

We evaluated the influence of the insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) gene on coronary plaque morphology and calcification in patients with angiographically documented coronary artery disease (CAD).

BACKGROUND

The ACE I/D polymorphism has been associated with an increased risk of myocardial infarction in patients with the DD genotype but not with the presence of native CAD.

METHODS

We studied 146 patients undergoing percutaneous transluminal coronary angioplasty for stable angina pectoris by means of preinterventional intravascular ultrasound (IVUS). Qualitative and quantitative criteria were used to classify the target lesions as poorly or highly echoreflective or as calcified. Genomic deoxyribonucleic acid was analyzed by polymerase chain reaction (PCR) to identify the I/D polymorphism, with a second insertion-specific PCR in DD genotypes to prevent mistyping.

RESULTS

The ACE genotype groups (DD 46, ID 68, II 32) were well matched for the basic characteristics. Patients with the DD genotype had significantly more calcified lesions (DD 80%, ID 57%, II 66%; unadjusted odds ratio [OR] 2.88, 95% confidence interval [CI] 1.30 to 6.92, p = 0.008) and more calcifications >180 degrees of the vessel circumference (DD 22%, ID 10%, II 6%; OR 2.80, 95% CI 1.05 to 7.63, p = 0.03). The prevalence of myocardial infarction was not significantly associated with coronary calcification (OR 1.44, 95% CI 0.72 to 2.88, p = 0.31).

CONCLUSIONS

Patients with CAD and the ACE DD genotype have a significantly higher incidence and greater extent of coronary lesion calcification, as determined by IVUS. This finding indicates that the ACE I/D gene polymorphism is related to the development or progression of atherosclerotic plaque calcification.

The deletion/insertion polymorphism of the angiotensin converting enzyme gene and cardiovascular-renal risk

OBJECTIVE

This meta-analysis attempted to derive pooled estimates for the associations between various cardiovascular-renal disorders and the deletion/insertion (D/I) polymorphism of the angiotensin converting enzyme (ACE) gene.

METHODS

Case-control studies were combined, using the Mantel-Haenszel approach. Joint P values for continuous variables were calculated by Stouffer's method. Continuous measurements reported in different units were expressed on a percentage scale using the within-study mean of the II genotype as the denominator.

RESULTS

The computerized database used for this analysis included 145 reports with an overall sample size of 49 959 subjects. Overall, possession of the D allele was associated with an increased risk of atherosclerotic and renal microvascular complications. In comparison with the II reference group, the excess risk in DD homozygotes (P < 0.001) was 32% for coronary heart disease (CHD; 30 studies), 45% for myocardial infarction (20 studies), 94% for stroke (five studies) and 56% for diabetic nephropathy (11 studies). The corresponding risk in DI heterozygotes amounted to 11% (P= 0.02), 13% (P= 0.02), 22% (P= 0.10) and 40% (P < 0.001), respectively. Hypertension (23 studies), left ventricular hypertrophy (five studies), hypertrophic or dilated cardiomyopathy (eight studies) and diabetic retinopathy (two studies) were not related to the DI polymorphism. Publication bias was observed for CHD, myocardial infarction and microvascular nephropathy, but not hypertension. In studies with DNA amplification in the presence of insertion-specific primers, the risk associated with the DD genotype increased to 150% [95% confidence interval (CI) 76-256; four studies] for diabetic nephropathy, but decreased to 12% (95% CI -3 to 28; seven studies) for CHD and 14% (95% CI -6 to 37; four studies) for myocardial infarction. On the other hand, the pooled odds ratios did not materially change if the meta-analysis was limited to articles published in journals with an impact factor of at least 4. Furthermore, compared with the II control group, the circulating ACE levels (29 studies) were raised 58 and 31% (P < 0.001) in DD and DI subjects, respectively. In contrast, plasma renin (10 studies), systolic and diastolic blood pressure (46 studies) and body mass index (30 studies) were not associated with the D allele.

CONCLUSION

The D allele is not associated with hypertension, but behaves as a marker of atherosclerotic cardiovascular complications and diabetic nephropathy. These associations do not necessarily imply a causal relationship and may have been inflated by publication bias. Nevertheless, their possible therapeutic implications may be subject to further investigation in prospective (intervention) studies.