Ethnic differences in the formation of small LDL particles in Asians: a comparison of Koreans, Japanese and Mongolians

LDL particle heterogeneity, and its association with other established cardiovascular risk factors in a young Indian industrial population

OBJECTIVE

Low density lipoprotein (LDL) particles are heterogeneous in terms of size, density, chemical composition and electric charge with certain particle of LDL being more atherogenic than the others. The present study aimed to look at the LDL particle heterogeneity, particle size and association with other cardiovascular disease (CVD) risk factors in young Indian industrial population.

METHODOLOGY

600 employees of an industry of Delhi, aged 20-39 years were selected for the study. Data on demographics, individual characteristics associated with major risk factors of CVD, past medical history, clinical and anthropometric profile was collected. Fasting glucose, lipid profile, apolipoprotein (A1, B, and E), lipoprotein (a), high sensitive C-reactive protein (hsCRP) and insulin were estimated. LDL particle size was determined in ethylenediamminetetraacetate (EDTA) plasma by 3% polyacrylamide gel electrophoresis.

RESULT

We found a prevalence of small dense LDL phenotype (LDL size ≤ 26.3) in 27.4% of males and 24.0% of females. The mean waist circumference, blood pressure, triglycerides (TAG), cholesterol, hsCRP, apolipoprotein (A1, B and E) and insulin were higher in males whereas mean high density lipoprotein was higher in females. Females also had a significantly higher mean LDL particle diameter as compared to males.

CONCLUSION

TAG, physical activity and lipoprotein (a) correlated with small dense LDL in this young Indian population.

Comparative study of the cardio-ankle vascular index and ankle-brachial index between young Japanese and Mongolian subjects

Mongolian people have higher mortality and morbidity rates due to cardiovascular disease (CVD) than Japanese people. The cardio-ankle vascular index (CAVI) and ankle-brachial index (ABI) are both atherosclerosis-related indexes. Presently, there is no comparative information on CAVI and ABI among young subjects between Mongolian and Japanese people. A total of one hundred Mongolian (men: 39%, mean age: 20.9+/-2.2 years) and 115 Japanese volunteers (men: 39%, mean age: 22.0+/-1.8 years) were recruited from among university students. The body mass index (BMI), heart rate (HR), blood pressure (BP), CAVI, ABI, carotid intima-media thickness, blood total cholesterol (TC), glucose and C reactive protein levels were measured. The levels of BMI, HR and diastolic BP were significantly higher, and TC and glucose were significantly lower in the Mongolian subjects than in the Japanese subjects. The CAVI values (median (interquartile range): 6.5 (5.8-7.0) vs. 5.6 (5.2-6.0)) and ABI (1.11 (1.05-1.17) vs. 1.09 (1.05-1.15)) were significantly higher in the Mongolian subjects than in the Japanese subjects. The patterns of correlation between CAVI, ABI and other atherosclerotic parameters were different: in age-, gender- and BMI-adjustment correlation tests for CAVI and ABI, HR (r=-0.25 for CAVI and ABI) showed a correlation in the Mongolian subjects, and for ABI systolic BP (r=-0.28) showed a correlation in the Japanese subjects. These results suggest that Mongolian subjects may be at higher risk of CVD, even among younger individuals, than Japanese subjects.

Greater adverse effects of cholesterol and diabetes on carotid intima-media thickness in South Asian Indians: comparison of risk factor-IMT associations in two population-based surveys

Asian Indians appear particularly susceptible to coronary heart disease compared with other ethnic groups. We compared the effects of vascular risk factors on carotid intima-media thickness (IMT) in a population of South Asians from Andhra Pradesh, India with a population of Caucasians from Perth, Australia. Cardiovascular risk factors and ultrasound-assessed carotid IMT were measured in randomly selected adults from two villages in rural India (n=303) and compared to those for randomly sampled adults from Australia (n=1111). Regression models with interaction terms were used to compare the strengths of associations between risk factors and carotid IMT, in these two populations. There were stronger associations of cholesterol (p for interaction=0.009) and diabetes (p=0.04) with carotid IMT in the Indian compared to the Australian population. Also, while increasing HDL-cholesterol was associated with decreasing carotid IMT in the Australian population the reverse was true for the Indian population (p<0.001). The associations with IMT of blood pressure, triglycerides, age, HDL to total cholesterol ratio, glucose, BMI, waist, waist to hip ratio and smoking were not different between the populations. Greater adverse effects of total cholesterol and diabetes on atherosclerosis and no protective effect of HDL-cholesterol amongst Asian Indians provide a novel possible explanation for observed excess rates of cardiovascular disease amongst these populations.