Coronary heart disease risks in Asian Indians

Conventional and Advanced Lipid Parameters in Premature Coronary Artery Disease Patients in India

BACKGROUND

Coronary artery disease (CAD) is the leading cause of death worldwide and has assumed alarming proportions in India with gradual increase in its incidence and prevalence over the last decade. India is in the middle of epidemic of coronary artery disease which is leading cause of hospital admissions, morbidity and mortality. In the Indian population, there is higher tendency to develop CAD at a younger age, which cannot be explained on the basis of conventional lipid parameters.

AIM

The purpose of this study is to find advanced lipid parameters which correlate better with premature CAD, as compared to the conventional lipid parameters.

MATERIALS AND METHODS

Thirty middle aged individuals suffering from premature CAD and 30 age and gender matched healthy individuals without any history of clinical evidence suggestive of CAD were studied. Fasting venous blood samples of all the subjects under study were collected after an overnight fasting and conventional lipid parameters and advanced lipid parameters (i.e. oxidized LDL, Lp (a), ApoA-1, small dense LDL, ApoB) were estimated. Correlation of conventional and advanced lipid parameters with premature CAD and among each other was calculated using Pearson correlation coefficient.

RESULTS

In our study the values of ox-LDL, sdLDL, Lp (a) and ApoB, total cholesterol, TG, LDL-C were significantly higher while HDL-C and Apo A1 and were significantly lower in cases than in controls. Advanced lipid parameters have higher correlation with premature CAD as compared to conventional lipid parameters. Ox-LDL show the highest correlation coefficient (r=+0.89) among these parameters followed by Lp (a) (r=+0.86) and ApoB (r=+0.79).

CONCLUSION

Advanced lipid parameters (i.e. oxidized LDL, Lp (a), ApoA-1, small dense LDL, ApoB) are better discriminator of premature CAD as compared to conventional lipid parameters (total cholesterol, triglycerides, low density lipoprotein and high density lipoprotein). Oxidised LDL, small dense LDL and lipoprotein (a) can explain occurrence of CAD in normolipidemic patients and proved to be better markers for explaining high degree of prematurity, morbidity and mortality of CAD in Indian population. They can prove to be better marker for early detection and intervention in premature CAD and site for targeted drug therapy.

APOA1 gene polymorphisms in the South Asian immigrant population in the United States

BACKGROUND:

Coronary artery disease (CAD) is a leading cause of death in the United States. South Asian immigrants (SAIs) from the Indian subcontinent living in the US are disproportionately at higher risk of CAD than other immigrant populations. Unique genetic factors may predispose SAIs to increased risk of developing CAD when adopting a Western lifestyle including a higher-fat diet, more sedentary behavior and additional gene-environment interactions. SAIs are known to have low levels of the protective high density lipoprotein (HDL) and an altered function for Apo-lipoprotein A-1 (ApoA1), the main protein component of HDL cholesterol. One gene that may be genetically distinctive in this population is APOA1 which codes for ApoA-1 protein, a potentially important contributing factor in the development of CAD.

MATERIALS AND METHODS:

DNA sequencing was performed to determine the status of the seven single-nucleotide polymorphisms (SNPs) in the APOA1 gene from 94 unrelated SAI adults. Genotypes, allelic frequencies, and intragenic linkage disequilibrium of the APOA1 SNPs were calculated.

RESULTS:

Several polymorphisms and patterns were common among persons of south Asian ethnicity. Frequencies for SNPs T655C, T756C and T1001C were found to be different than those reported in European Caucasian individuals. Linkage disequilibrium was found to be present between most (13 of 15) SNP pairings indicating common inheritance patterns.

CONCLUSIONS:

SAIs showed variability in the sequence of the APOA1 gene and linkage disequilibrium for most SNPS. This pattern of APOA1 SNPs may contribute to decreased levels of HDL cholesterol reported in SAIs, leading to an increased risk for developing CAD in this population.

Cardiovascular disease risk in immigrants: what is the evidence and where are the gaps?

OBJECTIVES

This study systematically reviewed the peer-reviewed literature to establish morbidity and mortality from myocardial infarction (MI) and stroke among immigrant populations.

METHODS

The review considered only studies published between 1986 and 2008 that provided data on MI or stroke morbidity/mortality among first-generation immigrants. A prespecified search strategy identified 58 studies for possible inclusion. Of these, 12 met the inclusion criteria.

RESULTS

Immigrant MI mortality and morbidity varied by host country with no consistent pattern from one country or region. However, there was an overall trend for increasing risk of MI among immigrants worldwide. Chinese and African immigrants had consistently higher stroke mortality.

CONCLUSION

MI and stroke incidence and prevalence among first-generation immigrants are related to both genetic and environmental factors, but the relative contribution of each is unclear. Prospective studies are needed to identify genetic and behavioral characteristics associated with stroke among Chinese immigrant populations.

Possible ethnic differences in plasma homocysteine levels associated with coronary artery disease between south Asian and east Asian immigrants

BACKGROUND

Hyperhomocysteinemia has been identified as a risk factor for coronary artery disease (CAD). South Asians appear to have a high incidence of CAD, while East Asians have a very low incidence.

HYPOTHESIS

The present study was undertaken because the relative association of plasma homocysteine levels (PH) with CAD in South Asians (SA = Indian, Pakistani, Sri Lankan) and East Asians (EA = Chinese, Japanese) is not known.

METHODS

Fasting PH were drawn on all patients with CAD of SA (age 62.4+/-1.1 years, 72 men, 14 women) and EA (age 61.8+/-3.0 years, 13 men, 4 women) descent. These were compared with PH available from Caucasian (CA) patients (age 61.1+/-1.1 years, 89 men, 17 women) with CAD.

RESULTS

The PH in SA, EA, and CA patients were 11.0+/-0.5, 7.6+/-0.5, and 10.8+/-0.6 micromol/l, respectively (p<0.001 between EA and SA/CA). Percentages of SA, EA, and CA with elevated PH (> 12.0 micromol/l) were 33.7, 5.9, and 28.2%, respectively. There were no significant differences in the lipid subfractions between the SA and EA group. History of smoking was significantly higher in the EA (52.9 vs. 26.2%), while hypertension and diabetes mellitus had similar prevalences.

CONCLUSION

Significant differences in PH of SA versus EA patients with CAD exist. The relative contribution of homocysteine in the development of CAD appears to be less in EA immigrants. In contrast, the association between CAD and PH in SA immigrants appears to be similar to that of Caucasians.

Long-term prognosis of south Asians following acute coronary syndromes

BACKGROUND

South Asians (SAs) have a higher prevalence of coronary artery disease than Caucasians. The long-term prognosis following acute coronary syndromes (ACS) in SA compared with non-SA patients is unclear.

OBJECTIVES

To compare the long-term adverse cardiovascular outcomes between SA and non-SA patients who have ACS.

METHODS

A case-control study of 65 consecutive SA patients admitted with ACS to the McGill University Health Centre (Montreal, Quebec) between 1995 and 2000 was conducted. Control subjects included 65 non-SA patients admitted to the same hospital with ACS matched by age, sex and year of hospitalization.

RESULTS

The mean +/- SD age was 59.7+/-9.9 years and 12% of patients were women. There were more cases of diabetes mellitus among the SA patients than non-SA patients (43% versus 23%, respectively). Only 19% of SA patients were active smokers, compared with 34% of non-SA patients. At one year, 35% of SA patients had undergone coronary artery bypass graft surgery, compared with 22% of non-SA patients. One-year mortality was increased among the SA patients compared with the non-SA patients (6% versus 2%, respectively). However, SA ethnicity was not an independent predictor of one-year adverse cardiovascular outcomes.

CONCLUSIONS

The present study demonstrated an increased prevalence of diabetes mellitus among the SA patients with ACS compared with non-SA patients. SA patients had increased one-year mortality compared with non-SA patients. However, SA ethnicity was not an independent predictor of one-year mortality and coronary intervention.

The trend of cardiovascular disease in immigrants in Sweden

Little is known as to whether the declining trend in cardiovascular disease (CVD) and coronary heart disease (CHD) in the Western countries has reached the immigrant populations. Incidence rates of CVD and CHD between 1991-1993 and 1997-1999 were compared by analysing the relative risk (RR) using the Poisson regression model and the data from 1991-1993 within each group as a reference. The whole Swedish population aged 35-74 years was included and we focused on 12 different immigrant groups. The morbidity from CHD in men from Sweden, Finland and countries in the OECD decreased slightly in an age-adjusted model (RR: 0.91, 0.93, and 0.88, respectively) during the 1990s. The opposite results were observed in women from Southern Europe, Turkey and Iran, in whom CHD morbidity increased (RR: 1.35, 1.54 and 1.40, respectively). The declining trend in CVD and CHD is continuing among men from Sweden, Finland and the OECD countries, but it is unchanged for women from these countries and all other groups studied, and even with increases in some female groups. This might be a sign of a breaking trend in these diseases.

Hospitalization for heart disease, stroke, and diabetes mellitus among Indian-born persons: a small area analysis

BACKGROUND

We set out to describe the risk of hospitalization from heart disease, stroke, and diabetes among persons born in India, all foreign-born persons, and U.S.-born persons residing in New York City.

METHODS

We examined billing records of 1,083,817 persons hospitalized in New York City during the year 2000. The zip code of each patient's residence was linked to corresponding data from the 2000 U.S. Census to obtain covariates not present in the billing records. Using logistic models, we evaluated the risk of hospitalization for heart disease, stroke and diabetes by country of origin.

RESULTS

After controlling for covariates, Indian-born persons are at similar risk of hospitalization for heart disease (RR = 1.02, 95% confidence interval 1.02, 1.03), stroke (RR = 1.00, 95% confidence interval, 0.99, 1.01), and diabetes mellitus (RR = 0.96 95% confidence interval 0.94, 0.97) as native-born persons. However, Indian-born persons are more likely to be hospitalized for these diseases than other foreign-born persons. For instance, the risk of hospitalization for heart disease among foreign-born persons is 0.70 (95% confidence interval 0.67, 0.72) and the risk of hospitalization for diabetes is 0.39 (95% confidence interval 0.37, 0.42) relative to native-born persons.

CONCLUSIONS

South Asians have considerably lower rates of hospitalization in New York than reported in countries with national health systems. Access may play a role. Clinicians working in immigrant settings should nonetheless maintain a higher vigilance for these conditions among Indian-born persons than among other foreign-born populations.

Genes, diet and serum lipid concentrations: lessons from ethnically diverse populations and their relevance to coronary heart disease in Asia

PURPOSE OF REVIEW

The burden of coronary heart disease (CHD) in Asia has risen in tandem with socio-economic development and urbanization. Although all ethnic groups have been affected, some appear to be at particularly high risk. The basis of these ethnic differences remains poorly understood.

RECENT FINDINGS

Differing levels of risk factors for CHD have been observed between ethnic groups. Previous studies, however, may be confounded by a large ethnic variation in socio-economic status and place of residence. Few studies have taken dietary factors into account. Recent studies involving Chinese, Malays and Asian Indians living in Singapore suggest that neither dietary nor genetic factors, taken in isolation, sufficiently explain ethnic differences in serum lipid profiles. Several genetic variants in key candidate genes (apolipoprotein E, APOE, cholesteryl ester transfer protein, CETP and hepatic lipase, LIPC) have recently been found to modulate the association between dietary factors and serum lipid concentrations in these ethnic groups and in other populations.

SUMMARY

To fully evaluate the differences in CHD risk between ethnic groups, environmental exposures, including dietary factors need to be carefully evaluated, and gene-environment interactions that may give rise to these differences need to be taken into account. These are critical steps in the development of targeted strategies to contain the epidemic of coronary heart disease in Asia. An understanding of the basis of these differences may also provide insights into the pathogenesis of disease that one cannot get through the examination of more homogenous populations.

Lipids and coronary heart disease in Asia

In Western countries, it has been shown that coronary heart disease (CHD) is related to high serum total cholesterol (TC) levels. In less developed continents such as Asia and Africa, serum lipid levels are low and CHD incidence is much lower as compared with Western countries. With growing urbanization and industrialization in Asia, it has been shown that there is a concomitant rise in the level of serum TC and with it a rise in CHD. In all the Asian countries, serum TC levels are also higher in the urban compared with the rural population. Singapore, the only Asian country which is 100% urbanized since 1980, showed a rise of serum TC similar to that seen in the US and UK from the 1950s to the 1980s followed thereafter by a fall. This is reflected in the trend (rise followed by a fall) of CHD morbidity and mortality as well. In spite of a declining trend in serum TC level, CHD morbidity and mortality are still high in Singapore and comparable to the Western countries. The rest of the Asian countries show a different pattern from Singapore. In general, there is still a rising trend in serum TC level and in CHD mortality in most Asian countries. However, Japan is considered an exception in having a decreasing CHD mortality in spite of an increasing trend in serum TC. This may be attributed to a better control of other CHD risk factors such as hypertension and smoking. The rising trend in serum TC level remains a cause for concern, as this will emerge as a major problem for CHD morbidity and mortality in the future.

Analysis of the apo(a) size polymorphism in Asian Indian populations: association with Lp(a) concentration and coronary heart disease

Most studies aiming to detect associations of genetic variation with common complex diseases, e.g. coronary heart disease (CHD) have been performed in populations with a western lifestyle but it is unclear whether associations detected in one geographic group exist also in others. We here have determined lipoprotein(a) levels and apo(a) K-IV-2 repeat genotypes in CHD patients (N=254) and controls (N=480) from two Asian Indian populations (Tamil Nadu and New Delhi). In both populations and also in the pooled dataset median Lp(a) levels were significantly elevated in the patients (27.4 mg/dl) compared with the controls (17.6 mg/dl). Apo(a) K-IV-2 allele frequencies were not different between the CHD patients and controls and thus did not explain the increased Lp(a) levels in CHD patients. Contrary to what has recently been observed in Black and White men short (K-IV<or=22) alleles associated with high Lp(a) concentration were not overrepresented in the patients. Rather, short (K-IV<or=22), intermediate (K-IV 23-29) and long (K-IV>or=30) apo(a) alleles were all associated with higher Lp(a) levels in the patients. Accordingly relative risk (estimated as odds ratio) for CHD rose continuously with increasing Lp(a) but was independent of apo(a) allele length. Together with previous studies our results indicate that the relation between apo(a) genotypes, Lp(a) levels, and CHD may be heterogeneous across ethnic groups and that it depends on the genetic architecture of the Lp(a) trait in a given population whether an association of K-IV-2 repeat length with CHD exists or not.

Cardiovascular risk factors in ethnic minority women aged < or =30 years

Men and women of African and South Asian ancestry in the United States are increasingly recognized as being at greater risk for coronary heart disease (CHD) than Caucasians of European ancestry. Relatively little data on the genetic and lifestyle risk factors that predispose women to CHD in these ethnic minorities are available. We compared coronary risk factors in a volunteer sample of African-American, Asian Indian American, and Caucasian American women of college age. Life style, dietary, hemodynamic and anthropometric parameters, and laboratory data were sought from 70 subjects in each ethnic group. African-American women were found to have lower triglyceride levels and higher apolipoproten A-1, high-density lipoprotein (HDL), lipoprotein (a) (Lp(a)), fibrinogen, and fasting insulin levels. They also consumed more fat and cholesterol than their peers, had a higher percentage of body fat, body weight, and body mass indexes, and reported less physical activity than Caucasians. Asian Indian American women had higher Lp(a), HDL, and fibrinogen levels than Caucasian American women, and also reported less physical activity. Thus, young African- American and Asian Indian American women have several modifiable risk factors as well as some nontraditional lipid risk factors that warrant consideration for explaining the increased prevalence of CHD in these ethnic groups. The tendency toward peripheral insulin insensitivity and increased body fat in this age group of African-American women suggests diet and exercise may reduce the risk of subsequent CHD.

Postprandial lipid metabolism and insulin sensitivity in young Northern Europeans, South Asians and Latin Americans in the UK

The aim of this study was to determine whether the higher susceptibility to coronary heart disease and diabetes in South Asian immigrants to the United Kingdom compared with the Caucasian population may reflect insulin resistance and altered postprandial lipid metabolism. We also wished to study Latin Americans, an ethnic group that has not been previously studied in the United Kingdom. The intention was to carry out a detailed study in a relatively small number of subjects to provide essential baseline information for larger epidemiological studies. Postprandial lipaemia was measured in 25 subjects (eight South Asians, eight Latin Americans and nine Northern Europeans) who resided in the United Kingdom. Results from the postprandial studies were correlated to insulin sensitivity measured by the insulin tolerance test, food intake, anthropometry and adipose tissue fatty acid composition. In South Asians, postprandial glucose and insulin concentrations were greater than in the other groups (P<0.01 and <0.05, respectively), although there were no differences in postprandial triacylglycerol concentrations or in insulin sensitivity assessed with the insulin tolerance test. The decreased glucose tolerance in this group could not be explained by differences in percentage body fat, body mass index, or by dietary intake measured by food records or adipose tissue fatty acid composition. We conclude that postprandial lipaemia is not affected in young South Asians compared to Northern Europeans although glucose intolerance is detectable. The results from the present study should help in the design of further postprandial lipid studies in different ethnic groups.

Prevalence of coronary artery disease and its relationship to lipids in a selected population in South India: The Chennai Urban Population Study (CUPS No. 5)

OBJECTIVES

The aim of this study was to assess the prevalence and risk factors for coronary artery disease (CAD) in a native urban South Indian population.

BACKGROUND

High prevalence rates of premature CAD have been reported in migrant Asian Indians. There are very few studies on CAD in native Indians living in the Indian subcontinent.

METHODS

The Chennai Urban Population Study (CUPS) is an epidemiological study involving two residential areas in Chennai in South India. Of the total of 1,399 eligible subjects (age > or =20 years), 1,262 (90.2%) participated in the study. All the study subjects underwent a glucose tolerance test and were categorized as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT) or diabetes. Twelve-lead electrocardiogram (ECG) was performed in 1,175 individuals (84%). Coronary artery disease was diagnosed based on previous medical history or Minnesota coding of ECGs.

RESULTS

The overall prevalence rate of CAD is 11.0% (age standardized, 9.0%). The prevalence rates of CAD were 9.1%, 14.9% and 21.4% in those with NGT, IGT and diabetes, respectively. Prevalence of CAD increased with an increase in total cholesterol (trend chi-square: 26.2, p < 0.001), low-density lipoprotein (LDL) cholesterol (trend chi-square: 24.5, p < 0.001), triglycerides (trend chi-square: 9.96, p = 0.002) and total cholesterol/high-density lipoprotein ratio (trend chi-square: 6.14, p = 0.0132). Multiple logistic regression analysis identified age (odds ratio [OR]: 1.05, p < 0.001) and LDL cholesterol (OR: 1.009, p = 0.051) as the risk factors for CAD.

CONCLUSIONS

The prevalence of CAD is rising rapidly in urban India. Lifestyle changes and aggressive control of risk factors are urgently needed to reverse this trend.

Cord blood apolipoprotein-E genotype distribution and plasma lipid indices in newborns of different ethnicity

We hypothesized that apolipoprotein-E (apo-E) genotypes would be associated with plasma lipid indices in newborns of South Asian (SA) ancestry but not in newborns of African (Afr) ancestry. Cord blood was obtained by consecutive sampling at maternity hospitals in the Caribbean Islands of Trinidad and Curaçao. Apolipoprotein-E genotypes, cholesterol, triglycerides, apo-A, apo-B and Lipoprotein (a) (Lp(a)) were measured in 294 newborns in Trinidad and 234 in Curaçao. The apo-B/apo-AI ratio and an adapted lipid tetrad index (i.e. cholesterol x triglycerides x Lp(a)/apo-AI) were calculated. In Trinidad, apo-E allele frequencies and genotype distributions of Afr and SA were significantly (p < 0.001) different (Afr: n = 71: apo-e2 : e3 : e4 = 10.4 : 66.4 : 23.2%; SA: n = 98; e2 : e3 : e4 = 3.5 : 83.1: 13.4%). The Mixed group (SA + Afr) had apo-E allele frequencies in between those of SA and Afr groups (n = 115; e2 : e3 : e4 = 7 : 76 : 17%). Lipid indices of appropriate for gestational age and term newborns were comparable, except for lower Lp(a) (SA = 29+/-4; Afr = 46+/-5; Mixed = 41+/-5 mg L(-1)) and lower adapted lipid tetrad index (29.4+/-4.8; 41.9+/-5.4; 41.4+/-7.0) in SA. Apo-E allele frequencies of Curaçao newborns were: apo-e2 : e3 : e4 = 10.5 : 72.6 : 16.9%. Their Lp(a) levels were significantly higher (68+/-3 mg L(-1)) than that of the Trinidadian sample (38+/-3; p < 0.0001). Apolipoprotein-E4 had an apo-B-increasing effect and apo-E2 an apo-B-decreasing effect in Afr (r = 0.192, p = 0.003). Among Africans from Trinidad and Curaçao variations in apo-E4 and apo-E2 are associated with an apo-B-increasing effect and an apo-B-decreasing effect, respectively. There was no relationship between apo-E polymorphism and lipids among South Asians.

Increased prevalence of smaller and denser LDL particles in Asian Indians

There is increasing evidence to believe that Asian Indians are at an increased risk of coronary heart disease (CHD), which cannot be attributed to the common risk factors. Individuals with small, dense LDL phenotype are also known to be at increased risk of CHD. Our objective was to examine whether the prevalence of smaller and denser LDL particles is increased in Asian Indians. Thirty-nine Asian Indians (22 men and 17 women), aged 25 to 45 years, were matched with 39 whites for age and gender. Cholesterol profiles of lipoprotein classes and LDL subclasses were measured using the Vertical Auto Profile-II (VAP-II) and LDL-VAP-II methods, respectively. Six LDL subclasses (LDL1 to LDL6) have been identified using the LDL-VAP-II, with LDL1 and LDL6, respectively, being the most and least buoyant subclasses. The prevalence of small, dense LDL type (subjects with major LDL subclass 5 or 6) was significantly higher in Asian Indians compared with white subjects (44% versus 21%; P<0.05). The relative position of the major LDL density peak (LDL-Rf) on 0 to 1 scale in LDL-VAP-II density gradient was also significantly decreased in Asian Indians (0.462+/-0.076 versus 0. 505+/-0.086; P<0.02), suggesting an increased LDL density. Furthermore, this increased prevalence of small, dense LDL type appears to be due to the increased triglycerides (TG) (r for LDL-Rf versus TG=0.681, P<0.001), with fasting insulin being one of the important determinants of TG (r for TG versus fasting insulin=0.572, P<0.001). In addition, fasting insulin was significantly increased in Asian Indians with small, dense LDL type compared with other Asian Indians, suggesting a significant role of insulin resistance in increasing the prevalence of small, dense LDL type. We conclude that the increased prevalence of small, dense LDL observed in Asian Indians might contribute to their increased CHD risk.

Potential new cardiovascular risk factors: left ventricular hypertrophy, homocysteine, lipoprotein(a), triglycerides, oxidative stress, and fibrinogen

The 1996 Bethesda Conference acknowledged left ventricular hypertrophy, hyperhomocysteinemia, lipoprotein(a) excess, hypertriglyceridemia, oxidative stress, and hyperfibrinogenemia as possible new cardiac risk factors. This review summarizes the current literature that supports these conditions as cardiac risk factors. Left ventricular hypertrophy is an independent risk factor for vascular disease. Improvement or progression of left ventricular hypertrophy influences subsequent cardiovascular complications. Clinical trials are under way to assess the potential benefit of decreasing homocysteine levels. The role of lipoprotein(a) excess in vascular disease is controversial. The atherogenic potential of lipoprotein(a) seems to be neutralized by effective reduction of low-density lipoprotein cholesterol levels. Increasing evidence supports an independent role of hypertriglyceridemia in cardiovascular disease and a possible clinical benefit from decreasing triglyceride levels. Among antioxidant micronutrients, supplementation with vitamin E has been shown to be beneficial in primary and secondary prevention studies. Data supporting the use of other antioxidants are much weaker. Preliminary evidence suggests that reducing fibrinogen levels in patients with high baseline levels and coronary disease may be beneficial. Despite the potential relation between new risk factors and cardiovascular disease, routine clinical application of these conditions as cardiovascular risk factors would be premature. Evidence is needed that these conditions extend prognostic ability beyond conventional risk factors and that modification of these conditions can reduce the risk for cardiovascular events.

Paraoxonase genes and disease

The paraoxonase gene family contains at least three members, including PON1, PON2 and PON3, which are located on chromosome 7q21.3-22.1. Until recently, there has been little insight into the role of the respective gene products in human physiology and pathology. However, emerging evidence from biochemical and genetic experiments is providing clues about the role(s) of the products of these genes. For example, the PON1 gene product is serum paraoxonase, which is expressed mainly in the liver and which hydrolyzes organophosphates. Serum paraoxonase circulates on a subfraction of high-density lipoproteins and appears to use phospholipids on both low and high-density lipoprotein particles as a physiological substrate. This functional relationship could explain the reported associations between common variation in the PON1 gene and phenotypes related to atherosclerosis and lipoprotein metabolism. In contrast, the PON2 mRNA is expressed ubiquitously, and to date there are no mechanistic experiments that yield insights into its physiological role. However, there have been reports of association between common variation in PON2 and some metabolic quantitative phenotypes, such as plasma lipoproteins, plasma glucose, birthweight and atherosclerosis. Such genetic associations could point to the possible physiological role(s) of PON2. At present, the role of the PON3 gene product is very poorly understood. Complementary lines of research should soon clarify whether there might be merit in clinical testing for genetic variation in the paraoxonase gene family or whether the gene products might be good candidates for therapeutic interventions.

Quantitative comparison of angiographic characteristics of coronary artery disease in patients with noninsulin-dependent diabetes mellitus compared with matched nondiabetic control subjects

The angiographic characteristics of coronary artery disease (CAD) in noninsulin-dependent diabetes mellitus (NIDDM) patients were studied by quantitative coronary angiography (QCA). Fifty-seven consecutive NIDDM patients undergoing clinically indicated elective coronary angiography and 57 nondiabetic coronary artery disease (CAD) patients were individually matched for sex, age, and body mass index. Technically adequate coronary angiograms, available for 55 subjects in each group, were analyzed with third-generation QCA software. To evaluate the anatomic severity and extent of CAD, several QCA-derived parameters were incorporated into indexes describing various per-patient features of CAD. These measures reflect CAD severity, extent, and overall "atheroma burden," and were calculated separately for different coronary segments (i.e., left main, proximal, mid, and distal segments), for the different coronary arterial territories (i.e., left main, left anterior descending, left circumflex, and right), and for the entire coronary tree. No significant differences were found between the NIDDM and nondiabetic groups (global severity index, 51 +/- 14 vs 54 +/- 13, p = NS; global extent index, 34 +/- 13 vs 32 +/- 12, p = NS; global atheroma burden index, 27 +/- 16 vs 24 +/- 12, p = NS). We also found no between-group differences in proximal, mid, or distal segments, in separate vessel territories, or in left ventricular function. Our data suggest that CAD patients, with and without NIDDM, who have similar symptoms at a given age, have similar severity and extent of CAD.