Specific elevation in plasma tissue plasminogen activator antigen concentrations in South Asians relative to Europeans

Review: Diabetes and cardiac disease in South Asians

South Asians have a higher prevalence of diabetes, coronary heart disease and cardiovascular death. Their predisposition to insulin resistance partly explains this excess risk. After immigration, the adoption of a western diet allied to increased sedentary behaviour leads to weight gain, hypertension and hyperlipidaemia, factors which in turn combine to amplify the chances of getting heart disease. Further contributory factors are increased sub-clinical inflammation, increased thrombogenic tendency and higher serum homocysteine levels. South Asians with diabetes might do as well as White people with respect to intensive glycaemic and blood pressure control. However, there is little evidence for measures to reduce cardiovascular risk as South Asians have not been included as a subgroup in most large trials. Future prospective studies, including studies on the prevention of diabetes and cardiovascular disease in this high-risk population, are therefore urgently required.

Is hyperlipidemia a potential protective factor against intraoperative awareness in cardiac surgery?

Background

Intraoperative awareness is a dreaded complication that leads to psychological sequelae such as posttraumatic stress disorder, especially in patients undergoing cardiac surgery. This study investigated the incidence of awareness among patients receiving cardiac surgery and sought to identify the risk factors contributing to intraoperative awareness.

Methods

Patients with informed consent undergoing cardiac surgery from June to September in 2012 were enrolled. At least one structured interview was performed postoperatively with the modified Brice Interview Questionnaire to identify intraoperative awareness as confirmed awareness, possible awareness, and no awareness. Confirmed awareness events reported by patients were classified into different categories with the Michigan Awareness Classification Instrument. The questionnaire results were combined with the patient medical records. A logistic regression model was used to analyze the risk factors that may have led to intraoperative awareness.

Results

An estimated 2136 patients were included, and 1874 patients completed at least one interview. 83 patients (4.4 %) were identified as possible or confirmed awareness, among which 46 (2.5 %) reported confirmed awareness. Patients who experienced confirmed awareness were mostly of Class 1 and 2, 15 and 24 patients respectively, which represented isolated auditory and tactile perceptions. And 11 patients reported feelings of distress intraoperatively. Hyperlipidemia was associated with intraoperative awareness (OR = 0.499, 95 % CI = 0.252–0.989, p = 0.043) and using chi-square test, however, no significance was found with logistic regression.

Conclusion

Patients undergoing cardiac surgery are at high risk for intraoperative awareness. Distress is a common feeling in patients with intraoperative awareness. Hyperlipidemia is a potential protective factor for intraoperative awareness in cardiac surgery.

Explanatory models of coronary heart disease among South Asian immigrants

OBJECTIVE

This study investigated South Asians' explanatory models (EM) of CHD and compared them to the biomedical model as part of an effort to inform the development of culturally targeted CHD prevention messages.

METHODS

We conducted in-depth, semi-structured interviews in English, Hindi and Urdu with 75 respondents from a federally qualified health center and at a community center for South Asian immigrants in Chicago, Illinois.

RESULTS

While EMs of CHD included risk factors from the biomedical model, they also included psychosocial and spiritual risk factors. Respondents emphasized that stress causes CHD and suggested that CHD was caused by sudden or inexplicable factors. Few respondents discussed cholesterol, blood pressure, or diabetes as part of CHD prevention. Women and those with lower education had low perceptions of being at-risk for CHD.

CONCLUSION

South Asians' EMs of CHD encompassed the biomedical model; however, EMs also included psychosocial and spiritual factors.

PRACTICE IMPLICATIONS

Clinicians and health educators should be aware that South Asian individual's EM of CHD may include psychosocial and spiritual factors which can affect CHD prevention behaviors.

Type 2 diabetes and cardiovascular disease in South Asians

Type 2 diabetes (T2DM) is growing at a pandemic scale and is associated with a rapid increase in its complications such as cardiovascular diseases (CVD). This problem is even worse in South Asian population with South Asian people having a much higher prevalence of T2DM and CVD, occurring at an earlier age and being associated with premature and high mortality. This review looks in detail at the current knowledge on epidemiology and characteristic pathophysiology of T2DM and CVD (coronary heart disease, heart failure, stroke and peripheral vascular disease) in South Asian migrant population. Specific attention is also drawn to the role of novel risk factors and cultural and socioeconomic factors on occurrence and outcomes of these chronic diseases in this population. Finally the review makes recommendations on various measures including need for further research to tackle this serious health challenge facing the South Asian community.

Fat oxidation, fitness and skeletal muscle expression of oxidative/lipid metabolism genes in South Asians: implications for insulin resistance?

Background

South Asians are more insulin resistant than Europeans, which cannot be fully explained by differences in adiposity. We investigated whether differences in oxidative capacity and capacity for fatty acid utilisation in South Asians might contribute, using a range of whole-body and skeletal muscle measures.

Methodology/Principal Findings

Twenty men of South Asian ethnic origin and 20 age and BMI-matched men of white European descent underwent exercise and metabolic testing and provided a muscle biopsy to determine expression of oxidative and lipid metabolism genes and of insulin signalling proteins. In analyses adjusted for age, BMI, fat mass and physical activity, South Asians, compared to Europeans, exhibited; reduced insulin sensitivity by 26% (p = 0.010); lower VO_2max (40.6±6.6 vs 52.4±5.7 ml.kg⁻¹.min⁻¹, p = 0.001); and reduced fat oxidation during submaximal exercise at the same relative (3.77±2.02 vs 6.55±2.60 mg.kg⁻¹.min⁻¹ at 55% VO_2max, p = 0.013), and absolute (3.46±2.20 vs 6.00±1.93 mg.kg⁻¹.min⁻¹ at 25 ml O₂.kg⁻¹.min⁻¹, p = 0.021), exercise intensities. South Asians exhibited significantly higher skeletal muscle gene expression of CPT1A and FASN and significantly lower skeletal muscle protein expression of PI3K and PKB Ser473 phosphorylation. Fat oxidation during submaximal exercise and VO_2max both correlated significantly with insulin sensitivity index and PKB Ser473 phosphorylation, with VO_2max or fat oxidation during exercise explaining 10–13% of the variance in insulin sensitivity index, independent of age, body composition and physical activity.

Conclusions/Significance

These data indicate that reduced oxidative capacity and capacity for fatty acid utilisation at the whole body level are key features of the insulin resistant phenotype observed in South Asians, but that this is not the consequence of reduced skeletal muscle expression of oxidative and lipid metabolism genes.

Effects of aprotinin on short-term and long-term outcomes after coronary artery bypass grafting surgery

BACKGROUND

Recent studies demonstrated that aprotinin use would increase the short-term and long-term mortality and complications after coronary artery bypass grafting (CABG). This study was to investigate effects of aprotinin during isolated primary CABG on short-term and long-term outcomes in Chinese patients.

METHODS

We studied 5,103 consecutive Chinese patients who underwent isolated primary CABG from 1999 to 2005. Of all the patients, 4,122 received aprotinin during operation (aprotinin group) and 981 received no aprotinin or other antifibrinolytic therapy (control group). Short-term and long-term mortality and major complications were analyzed with multivariate regression analysis. Propensity adjustment method was used to minimize the selection bias between the two groups, and propensity matching method was used to yield two well-matched groups for further comparison.

RESULTS

Blood loss after operation was significantly reduced in the aprotinin group compared with the control group (p < 0.001). Aprotinin use was neither associated with the perioperative mortality (p = 0.45, relative risk, 1.34) or major complications, nor was it associated with long-term mortality (p = 0.21, relative risk, 1.26) and major adverse cardiac and cerebrovascular events (p = 0.82, relative risk, 0.98). After propensity adjustment for the baseline characteristics, we obtained similar results. In addition, comparison between the two well-matched groups showed no significant difference either in baseline characteristics or in short-term and long-term outcomes.

CONCLUSIONS

Aprotinin use during isolated primary CABG reduced blood loss significantly, but was not associated with short-term or long-term mortality and complications. Aprotinin use in relatively low-risk CABG patients was effective and safe in a Chinese (Asian) population.

Prevalence of metabolic syndrome and associated risk factors in Asian Indians

OBJECTIVE

This study examined the association between metabolic syndrome, lifestyle behaviors, and perception and knowledge of current health and cardiovascular disease (CVD) among Asian Indians in the US.

METHOD

The sample comprised of 143 adult Asian Indians recruited through health fairs for survey and bioclinical measures.

RESULTS

The prevalence of metabolic syndrome was 32%, much higher than other ethnic groups, did not vary by gender but increased with age. Respondents had high physical inactivity and poor knowledge of CVD risk factors. Dietary behavior, age, number of years lived in the US, self-rated physical and mental health and BMI were significant predictors and explained 40.1% of variance in metabolic syndrome score. Poorer physical health status had the greatest predictive influence on metabolic syndrome.

CONCLUSION

Asian Indians are a high risk group for CVD.

Ethnic differences in cardiovascular risk factors in healthy Caucasian and South Asian individuals with the metabolic syndrome

BACKGROUND

The metabolic syndrome is a cluster of atherothrombotic risk factors that are commonly associated with insulin resistance.

OBJECTIVES

The aim of this study was to investigate ethnic differences in insulin resistance and non-traditional cardiovascular risk factors in relation to the International Diabetes Federation (IDF) definition of the metabolic syndrome.

PATIENTS AND METHODS

A total of 245 healthy South Asians and 245 age- and sex-matched Caucasians were studied. C-reactive protein (CRP), complement C3, plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (t-PA) were measured and homeostasis model assessment-insulin resistance (HOMA-IR) was calculated from fasting plasma glucose and insulin levels.

RESULTS

Fifty Caucasian (20%) and 95 (39%) South Asian subjects had the metabolic syndrome as defined by the IDF. In South Asian subjects, HOMA-IR, CRP, C3, PAI-1 and t-PA were significantly higher in subjects with the metabolic syndrome. In contrast, in Caucasian individuals there was no difference in HOMA-IR or C3 levels and only CRP, PAI-1 and t-PA were higher in subjects with the metabolic syndrome. In a logistic regression model, plasma levels of CRP and PAI-1 were independent predictors of the metabolic syndrome in Caucasians, whereas plasma levels of C3 and t-PA as well as HOMA-IR were independent predictors of the metabolic syndrome in South Asian subjects.

CONCLUSIONS

In the cohort of individuals studied, the IDF definition of the metabolic syndrome was associated with insulin resistance in the South Asian but not the Caucasian population. This work also showed ethnic differences in non-traditional cardiovascular risk factors in the presence of the metabolic syndrome.

Coronary artery disease in South Asians: an emerging risk group

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide and was responsible for 7.2 million deaths in 2003. Various studies have pointed out that South Asians have a higher prevalence of CAD as compared with other ethnicities. South Asians may have a genetic predisposition to CAD; however, environmental, nutritional, and lifestyle factors may also be responsible. South Asians have a much higher prevalence of metabolic syndrome, diabetes, insulin resistance (and resultant hyperinsulinemia), central obesity, dyslipidemias (lower high-density lipoprotein, increased lipoprotein[a], higher triglyceride levels), increased thrombotic tendency (increased plasminogen activator inhibitor-1 and decreased tissue plasminogen activator levels), decreased levels of physical activity, and low birth weights ("fetal origins hypothesis"). In addition, the dietary indiscretions and sedentary lifestyle practiced by most South Asians puts them at a higher risk. A multidisciplinary approach involving the population at risk, healthcare personnel, and the government is required to diminish the incidence. Educational programs regarding the genetic predisposition as well as risk factors for CAD, physical activity, and dietary modifications need to be encouraged. There is a need for implementation of newer guidelines as well as a lower threshold for initiating therapeutic interventions in this population. Mass media should be involved to bring about behavioral changes, and these changes should be reinforced at the physician's level.

ADAMTS-13 plasma level determination uncovers antigen absence in acquired thrombotic thrombocytopenic purpura and ethnic differences

BACKGROUND

The recently discovered plasma enzyme ADAMTS-13 cleaves the A2-domain of von Willebrand factor (VWF). A defective cleaving protease results in unusually large VWF multimers, which cause thrombotic thrombocytopenic purpura (TTP).

AIM

Analysis of the ADAMTS-13 antigen levels in TTP patients compared with normal donors.

METHODS

An antigen ELISA test was built, based on high affinity anti-ADAMTS-13 monoclonal antibodies, which were generated using genetic immunization.

RESULTS

Specificity of the ADAMTS-13 antigen test was confirmed, as (i) plasma from a patient with acquired TTP but presenting without inhibitor did not contain antigen and (ii) the binding of recombinant ADAMTS-13 was inhibited by increasing amounts of normal plasma. The assay is sensitive as it can detect antigen levels as low as 1.6% of normal. The concentration in normal pooled human plasma was determined (1.03 +/- 0.15 microg mL(-1)) and arbitrarily set to 1 U mL(-1). The antigen levels in congenital TTP samples (34 +/- 21 mU mL(-1), n = 2), as well as in samples from patients with acquired TTP (231 +/- 287 mU mL(-1), n = 11), were clearly reduced when compared with normal Caucasian donors (951 +/- 206 mU mL(-1), n = 16). Remarkably, normal Chinese donors have a significantly lower antigen titer (601 +/- 129 mU mL(-1), n = 15), when compared with normal Caucasians.

CONCLUSIONS

Our results show that acquired TTP patients suffer mainly from ADAMTS-13 antigen depletion, thereby indicating the importance of ADAMTS-13 antigen determination in diagnosis and patient follow-up.

CVD risk factors and ethnicity--a homogeneous relationship?

Current understanding of cardiovascular disease risk (CVD) is derived largely from studies of Caucasians of European origin. However, people of certain ethnic groups experience a disproportionately greater burden of CVD including coronary heart disease (CHD) and stroke. Adoption of a Westernised lifestyle has different effects on metabolic and vascular dysfunction across populations, e.g. South Asians have a higher prevalence of coronary heart disease (CHD) and cardiovascular mortality compared with Europeans. African-Americans demonstrate higher rates of CHD and stroke while African/Caribbeans in the UK have lower CHD rates and higher stroke rates than British Europeans. Other non-European groups such as the Chinese and Japanese exhibit consistently high rates of stroke but not CHD, while Mexican Americans have a higher prevalence of both stroke and CHD, and North American native Indians also have high rates of CHD. While conventional cardiovascular risk factors such as smoking, blood pressure and total cholesterol predict risk within these ethnic groups, they do not fully account for the differences in risk between ethnic groups, suggesting that alternative explanations might exist. Ethnic groups show differences in levels of visceral adiposity, insulin resistance, and novel risk markers such as C-reactive protein (CRP), adiponectin and plasma homocysteine. The marked differences across racial and ethnic groups in disease risk are likely due in part to each of genetic, host susceptibility and environmental factors, and can provide valuable aetiological clues to differences in patterns of disease presentation, therapeutic needs and response to treatment. Ongoing studies should increase understanding of ethnicity as a potential independent risk factor, thus enabling better identification of treatment targets and selection of therapy in specific populations.