Association between plasma activities of semicarbazide-sensitive amine oxidase and angiotensin-converting enzyme in patients with type 1 diabetes mellitus.

AIMS/HYPOTHESIS: Plasma semicarbazide-sensitive amine oxidase (SSAO) is elevated in patients with type 1 and type 2 diabetes and has been implicated in the pathophysiology of diabetic late complications. The regulation of SSAO production remains unknown. We studied correlations between plasma SSAO activity and parameters associated with diabetic late complications. METHODS: Plasma SSAO was measured in a well-characterised group of 287 patients with type 1 diabetes. Standard statistical methods were used to investigate correlations with clinical parameters and components of the renin-angiotensin system. RESULTS: Overall, plasma SSAO was elevated, at 693+/-196 mU/l (mean+/-SD; normal controls 352+/-102 mU/l). Plasma SSAO was higher in the group with late complications or hypertension, and in patients treated with ACE-inhibitors. In univariate analysis a significant positive correlation (p<0.001, r=0.27) was found between plasma SSAO and serum ACE activity in patients untreated with ACE inhibitors or angiotensin II receptor antagonists (n=221), but plasma SSAO did not differ by ACE I/D genotype. Plasma SSAO correlated positively with duration of diabetes, HbA(1)c and plasma renin, and negatively with plasma angiotensinogen and body mass index. A multiple regression analysis including these variables resulted in serum ACE activity (p<0.001), ACE genotype (negatively, p<0.001) and HbA(1)c (p=0.023) as explaining variables. CONCLUSIONS/INTERPRETATION: Results suggest that a common factor is involved in the regulation of both plasma SSAO and serum ACE, which is different from the genetic determination of ACE activity.

Prediction of severe hypoglycaemia by angiotensin-converting enzyme activity and genotype in type 1 diabetes.

AIMS/HYPOTHESIS: We have previously shown a strong relationship between high angiotensin-converting enzyme (ACE) activity, presence of the deletion (D) allele of the ACEgene and recall of severe hypoglycaemic events in patients with Type 1 diabetes. This study was carried out to assess this relationship prospectively. METHODS: We followed 171 adult outpatients with Type 1 diabetes in a one-year observational study with the recording of severe hypoglycaemia. Participants were characterised by serum ACE activity and ACE genotype and not treated with ACE inhibitors or angiotensin II receptor antagonists. RESULTS: There was a positive relationship between serum ACE activity and rate of severe hypoglycaemia with a 2.7 times higher rate in the fourth quartile of ACE activity compared to the first quartile (p=0.0007). A similar relationship was observed for the subset of episodes with coma (2.9 times higher rate in fourth quartile compared to first quartile; p=0.048). The impact of serum ACE activity was most pronounced in C-peptide negative subjects (4.2 times higher rate in fourth quartile compared to first quartile; p=0.003), and in this subgroup carriers of the D allele of the ACEgene had higher rates of severe hypoglycaemia compared to the group homozygous for the insertion (I) allele. In a multiple regression analysis high serum ACE activity and impaired awareness of hypoglycaemia were identified as the only significant predictors of severe hypoglycemia. CONCLUSION: High ACE activity and the presence of the D allele of the ACE gene predict a high rate of severe hypoglycaemia in Type 1 diabetes.

Activity of angiotensin-converting enzyme and risk of severe hypoglycaemia in type 1 diabetes mellitus.

BACKGROUND: The insertion (I) allele of the angiotensin-converting-enzyme (ACE) gene occurs at increased frequency in endurance athletes. This association suggests that low ACE activity is favourable for performance in conditions with limited substrate availability. Such conditions occur in endurance athletes during competition and in diabetic patients during insulin-induced hypoglycaemia. Patients rely on preserved functional capacity to recognise hypoglycaemic episodes and avoid progression by self-treatment. We studied whether ACE activity is related to the risk of severe hypoglycaemia in type 1 diabetes. METHODS: Consecutive adult outpatients with type 1 diabetes, untreated with ACE inhibitors or angiotensin-II-receptor antagonists (n=207) reported their experience of mild and severe hypoglycaemia during the previous 1 year and 2 years. The patients were further characterised by diabetes history, degree of hypoglycaemia awareness, measurement of C-peptide, haemoglobin A(1c), and serum ACE concentrations, and determination of ACE genotype. FINDINGS: Patients with the DD genotype had a relative risk of severe hypoglycaemia in the preceding 2 years of 3.2 (95% CI 1.4-7.4) compared with those who had the II genotype. There was a significant relation between serum ACE activity and the rate of severe hypoglycaemia (relative risk per 10 U/L increment 1.4 [1.2-1.6]), corresponding to a 3.5 times higher risk for patients in the highest quartile than for those in the lowest quartile. Multiple regression analysis showed that the effect of the ACE genotype was explained by its influence on serum ACE activity and that the only other significant determinants of the risk of severe hypoglycaemia were the degree of hypoglycaemia awareness, b-cell function, and duration of diabetes of more than 20 years. INTERPRETATION: ACE activity is a clinically significant marker of the risk of severe hypoglycaemia in patients with type 1 diabetes, especially in those with impaired defence against hypoglycaemia. These findings need to be confirmed in prospective studies.

Angiotensinogen polymorphisms and elevated blood pressure in the general population: the Copenhagen City Heart Study.

In the present study, we tested the hypothesis that the Met235Thr and Thr174Met mutations were associated or not with elevated blood pressure. We genotyped 9100 women and men from the Danish general population, of whom 54% had elevated blood pressure. Of the 9100, 41% and 12% carried the Thr235 and Met174 mutations, respectively; the Met174 mutation always occurred on the same allele as the Thr235 mutation. On multifactorial logistic regression analysis, women homozygous for Thr235 versus noncarriers had an odds ratio for elevated blood pressure of 1.29 (95% CI 1.05 to 1.58), which increased to 1.50 (1.15 to 1.96) if they also were homozygous for Thr174 (noncarrier of Met174). Women homozygous for Thr235 also had an increased risk of isolated elevated systolic blood pressure (1.37; 1.02 to 1.84) and of mild blood pressure elevation (1.40; 1.10 to 1.77). We found no statistically significant association between elevated blood pressure and genotype in men or among genotype and systolic blood pressure, diastolic blood pressure, or pulse pressure in either gender. Homozygosity for both Thr235 and Thr174 was associated with a 10% increase in plasma angiotensinogen levels in both genders compared with homozygosity for Met235 and Thr174; however, systolic and diastolic blood pressures were positively correlated to plasma angiotensinogen levels in women only. In conclusion, in this large-scale study of the general population, double homozygosity for Thr235 and Thr174 in the angiotensinogen gene is associated with a 10% increase in angiotensinogen levels and is a risk factor for elevated blood pressure in women but not in men.

Common cholesteryl ester transfer protein mutations, decreased HDL cholesterol, and possible decreased risk of ischemic heart disease: The Copenhagen City Heart Study.

BACKGROUND: Cholesteryl ester transfer protein (CETP) mediates the transfer of cholesteryl ester from HDL in exchange for triglycerides in apolipoprotein B-containing lipoproteins. METHODS AND RESULTS: We studied 2 common mutations in CETP, A373P and R451Q, in 8467 healthy women and men from the Danish general population and in 1636 Danish women and men with ischemic heart disease. The prevalence of 373P and 451Q was 0.10 and 0.07, respectively, for heterozygous carriers and 0.003 and 0.002, respectively, for homozygous carriers. All carriers of the 451Q allele also carried the 373P allele. HDL cholesterol in female noncarriers, heterozygotes, and homozygotes of 373P was 1.74+/-0.01 (mean+/-SE), 1.62+/-0.02, and 1.38+/-0.09 mmol/L, respectively (ANOVA, P:<0.001). In men, equivalent values were 1.40+/-0.01, 1.26+/-0.02, and 1.19+/-0.09 mmol/L, respectively (ANOVA, P:<0.001). HDL cholesterol decreased similarly as a function of 451Q genotypes and all 373P/451Q genotype combinations. Furthermore, apolipoprotein AI and the HDL cholesterol/apolipoprotein AI ratio was also lower in carriers of either of these mutations for both sexes. Finally, the CETP genotype was not associated with risk of ischemic heart disease unless we adjusted for HDL cholesterol: female heterozygous and homozygous carriers versus noncarriers had 36% lower risk of ischemic heart disease (95% CI 4% to 57%); in male carriers, we observed a similar trend. CONCLUSIONS: The A373P/R451Q polymorphism in CETP is associated with decreases in HDL cholesterol of 0.12 to 0.36 mmol/L in women and 0.14 to 0.21 mmol/L in men and possibly with a paradoxical 36% decrease in the risk of ischemic heart disease in women.

Context-dependent and invariant associations between lipids, lipoproteins, and apolipoproteins and apolipoprotein E genotype.

Variation in apolipoprotein (apo)E genotypes predicts variation in plasma cholesterol and apoB; however, the context-dependent associations between high density lipoprotein (HDL) cholesterol, apoA-I, triglycerides, and lipoprotein[a] (Lp[a]) and this polymorphism remain unsettled. We genotyped 5,025 women and 4,035 men sampled to represent a white general population in the age range 20 to 80+ years (mean ages 58 and 57 years for women and men, respectively). The relative frequencies of the varepsilon22, varepsilon32, varepsilon42, varepsilon33, varepsilon43, and varepsilon44 genotypes were 0.005, 0.127, 0.027, 0.564, 0.251, and 0. 027, respectively. Variations in apoE genotype (in the order listed above) predicted stepwise increases in cholesterol and apoB in both genders (all ANOVAs: P < 0.001), and stepwise decreases in HDL cholesterol and apoA-I in women (both ANOVAs: P < 0.001), but not in men. In both genders varepsilon33 individuals had the lowest levels of nonfasting triglycerides, whereas the highest levels were found in individuals with varepsilon22 and varepsilon44 genotypes (both ANOVAs: P < 0.001). Finally, a stepwise increase in Lp[a] was seen in women (ANOVA: P < 0.001), but not in men. In women, the association between variation in nonfasting triglycerides and Lp[a], and variation in apoE genotypes was mainly seen in those with the highest alcohol consumption, similar to the consumption of most men. Variations in apoE genotype predicted 5% and 11% in women, and 2% and 6% in men, of the total variation in plasma cholesterol and apoB, respectively. Variation in levels of plasma lipoproteins is associated with variation in apoE genotypes in the population at large, with the most pronounced association in women, except for nonfasting triglycerides, for which the association is most pronounced in men.Whereas the associations between variation in plasma cholesterol and apoB and the variation in apoE genotypes seem invariant, the associations with variation in plasma HDL cholesterol, apoA-I, nonfasting triglycerides, and Lp[a] seem context dependent.

Elevated HDL cholesterol is a risk factor for ischemic heart disease in white women when caused by a common mutation in the cholesteryl ester transfer protein gene.

BACKGROUND: The level of HDL cholesterol is inversely related to the risk of ischemic heart disease. METHODS AND RESULTS: In 9168 women and men from a general population and 946 women and men with ischemic heart disease (all white), we tested the hypothesis that the Ile405Val mutation in the cholesteryl ester transfer protein gene (CETP) affects HDL cholesterol levels and the risk of ischemic heart disease. The relative frequencies of Ile/Ile, Ile/Val, and Val/Val carriers were 0.46, 0.43, and 0.11 for both women and men. Women with these 3 genotypes had mean HDL cholesterol levels of 1.68, 1.75, and 1.82 mmol/L, respectively (P<0.001, ANOVA), as well as a significant decrease in the ratio of total to HDL cholesterol (P=0. 002, ANOVA). On multiple logistic regression analysis, women not treated with hormone replacement therapy who were heterozygous or homozygous for Val405 had a 1.4-fold (95% CI 1.0 to 1.9) to 2.1-fold (95% CI 1.3 to 3.4) increase in the risk of ischemic heart disease. No significant associations were found in men. CONCLUSIONS: Increased HDL cholesterol levels caused by mutations in CETP are associated with an increased risk of ischemic heart disease in white women.

ACE gene polymorphism in cardiovascular disease: meta-analyses of small and large studies in whites.

The objective of this study was to assess the influence of the ACE gene insertion (I)/deletion (D) polymorphism on plasma ACE activity; blood pressure; and risk of myocardial infarction, ischemic heart disease, and ischemic cerebrovascular disease by comparing small and large studies. The meta-analyses are based on a literature search of MEDLINE up until April 1998 and assessment of bibliographies of published studies and reviews. Forty-six studies were selected, including a total of 32 715 white individuals. Plasma ACE activity was increased 40% and 71% for ID and DD versus II in small studies and 21% and 48% in large studies (small versus large: P<0.001 and P<0.001). Blood pressure was not influenced by genotype. Risk of myocardial infarction and ischemic heart disease was increased by 47% and 29%, respectively, for DD versus ID and II genotypes in small studies but not in large studies (small versus large: P<0.001 for risk of myocardial infarction and P=0.01 for risk of ischemic heart disease). Risk of ischemic cerebrovascular disease was not increased either in the small or in the largest study. In conclusion, the ACE gene polymorphism affects plasma ACE activity but not blood pressure and is not associated with increased risk of myocardial infarction, ischemic heart disease, or ischemic cerebrovascular disease in the largest studies.

ACE gene polymorphism as a risk factor for ischemic cerebrovascular disease.

BACKGROUND: Researchers have suggested that the deletional allele of the ACE (angiotensin-converting enzyme) gene insertion-deletion polymorphism is a potent risk factor for myocardial infarction. This association could not be confirmed in the Copenhagen City Heart Study, in which 10,150 persons were studied. The ACE gene polymorphism has also recently been suggested as a potent risk factor for ischemic cerebrovascular disease. OBJECTIVE: To investigate the association between ACE gene polymorphism and ischemic cerebrovascular disease. DESIGN: Two case-referent studies and a cross-sectional study. SETTING: University hospital in Copenhagen, Denmark. PARTICIPANTS: Case-referent study 1: 35 women and 38 men who developed ischemic cerebrovascular disease before 50 years of age compared with 1454 women and 1737 men from a general population sample. Case-referent study 2: 82 women and 137 men with ischemic cerebrovascular disease and carotid stenosis greater than 40% compared with 4273 women and 3091 men from the general population sample. Cross-sectional study of the general population sample: 67 women and 93 men with ischemic cerebrovascular disease compared with 4077 women and 3156 men without such disease. MEASUREMENTS: Genotype; age; body mass index; smoking habits; levels of lipids, lipoproteins, apolipoproteins, and fibrinogen; and diagnosis of hypertension, diabetes mellitus, and ischemic cerebrovascular disease. RESULTS: Odds ratios for ischemic cerebrovascular disease by ACE genotype classes were not significantly different from 1.0 in women or men in any of the three studies, separately or combined. In a logistic regression analysis that controlled for age and conventional cardiovascular risk factors, odds ratios in either sex still did not significantly differ from 1.0 in any study, separately or combined. CONCLUSION: In two case-referent studies, a cross-sectional study, and the three studies combined, no statistically significant difference was found in the development of ischemic cerebrovascular disease between genotype classes of the ACE gene polymorphism in women or men.

A common mutation (G-455--> A) in the beta-fibrinogen promoter is an independent predictor of plasma fibrinogen, but not of ischemic heart disease. A study of 9,127 individuals based on the Copenhagen City Heart Study.

A common mutation (G-455--> A) in the promoter region of the beta-fibrinogen gene has been associated with elevated plasma fibrinogen levels. Whether fibrinogen genotype affects plasma fibrinogen levels and risk of ischemic heart disease in the general population has not been studied. We investigated the association between fibrinogen genotype, plasma fibrinogen levels, and ischemic heart disease in a general population sample (n = 9,127). The A-allele (relative frequency, 0.20) was associated with elevated plasma fibrinogen levels in both genders (P < 0.001). While the effect of the A-allele on fibrinogen level was additive in men, the effect was dominant in postmenopausal women. The A-allele raising effect appeared to be two- to threefold greater in individuals with ischemic heart disease than in those without. An increase of 1 SD in plasma fibrinogen increased the odds ratio for ischemic heart disease by approximately 20% (P < 0.01 for women and < 0.005 for men). However, the frequency of the A-allele was similar in those with and without ischemic heart disease, and genotype was not a predictor of disease. These results demonstrate that the (G-455--> A) mutation in the promoter region of the beta-fibrinogen gene is associated with an increase in plasma fibrinogen in both genders in the general population. This increase does not appear to cause ischemic heart disease.

ACE gene polymorphism: ischemic heart disease and longevity in 10,150 individuals. A case-referent and retrospective cohort study based on the Copenhagen City Heart Study.

BACKGROUND: Homozygosity for the deletion allele (D) of the angiotensin-converting enzyme (ACE) gene insertion-deletion polymorphism has been suggested to be a potent risk factor for myocardial infarction. With one exception, the samples studied so far have been small and/or ethnically heterogeneous, and most investigators have studied men only. METHODS AND RESULTS: We investigated the association between ACE genotype and myocardial infarction as well as other manifestations of ischemic heart disease for both women and men in a case-referent study (n = 10,150) as well as in a retrospective cohort study (n = 7263). The cohort was from the ethnically homogeneous Danish population. Case subjects were from the same geographic area and had ischemic heart disease. Irrespective of the assumed degree of relative penetrance of the D allele, the odds ratios were not significantly different from 1.0 (P > .05) for ischemic heart disease, severe stenosis on coronary angiography, or myocardial infarction. There was also no association between ACE genotype and phenotypic variation in recognized risk factors for ischemic heart disease. Finally, the relative frequency of the D allele did not change as a function of age in subjects aged from 20 to > or = 80 years. CONCLUSIONS: In two large studies, a case-referent study and a retrospective cohort study in an ethnically homogeneous white population, there was no evidence for a statistically significant difference in the development of myocardial infarction or any other manifestations of ischemic heart disease between genotype classes of the ACE gene polymorphism in either women or men.

Effect of exogenous hyperinsulinaemia on atherogenesis in cholesterol-fed rabbits.

To examine the hypothesis that hyperinsulinaemia promotes atherosclerosis, cholesterol-fed rabbits were injected subcutaneously with 6 i.u. of human insulin (n = 16) or placebo (n = 20) daily for 24 weeks; injection of insulin resulted in hyperinsulinaemia for up to 16 h after injection. Compared to placebo rabbits, insulin-treated rabbits had higher levels of insulin antibodies in plasma, similar levels of intermediate density, low density and high density lipoprotein cholesterol and similar activities of hepatic and lipoprotein lipase in post-heparin plasma, but lower levels of plasma C-peptide, blood glucose, postprandial plasma triglycerides, plasma cholesterol and very low density lipoprotein cholesterol. On univariate analysis, with and without adjustment for differences in plasma cholesterol levels between the two groups, there were no significant differences in extent or severity of atherosclerosis between insulin and placebo rabbits. Furthermore, after combining the results from all the rabbits to examine plasma insulin levels and the other variables mentioned above as predictors of atherosclerosis severity, plasma insulin level was not a predictor, on univariate or multiple linear regression analysis; the first ranked independent predictors were postprandial intermediate density lipoprotein cholesterol in the arch, and postprandial plasma triglyceride in both the thoracic and abdominal aorta. These results suggest that exogenous hyperinsulinaemia does not promote atherogenesis in cholesterol-fed rabbits, but that postprandial levels of intermediate density lipoprotein cholesterol or plasma triglycerides may be involved in atherogenesis.

A prospective cardiovascular population study used in genetic epidemiology. The Copenhagen City Heart Study.

Rapid advances in molecular biology will in the near future allow insight into which mutations are important for determining an individual's susceptibility to cardiovascular disease, as well as to other multifactorial diseases. Methods for diagnosing mutations are today easy to use; however, strategies for determining the effect of a given mutation on phenotype, as well as on the susceptibility of carriers to disease, are less well established. In the present paper, we describe a DNA bank, consisting of more than 10,000 individuals, which--for a given mutation--will allow us to determine its frequency in the general population, the effect of the mutation on phenotype, and its influence on the development of cardiovascular as well as other diseases.