Cardiovascular Mortality, Habitual Exercise, and Particulate Matter 2.5 Exposure: A Longitudinal Cohort Study

INTRODUCTION

Habitual exercise may amplify the respiratory uptake of air pollutants in the lung, exacerbating the adverse effects of air pollution. However, it is unclear whether this can reduce the health benefits of habitual exercise (referred to as leisure-time exercise). Thus, the combined effects of habitual exercise and chronic exposure to ambient fine particulate matter 2.5 on cardiovascular mortality were examined among adults in Taiwan.

METHODS

A total of 384,128 adults were recruited between 2001 and 2016 and followed up to May 31, 2019. Participants' vital status was obtained by matching their unique identification numbers with records of cardiovascular death in the National Death Registry of Taiwan. A time-varying Cox regression model was used to analyze the data. Analyses were conducted in 2021.

RESULTS

Cardiovascular death risks were inversely associated with habitual exercise and positively associated with chronic exposure to particulate matter 2.5. The beneficial effects of habitual exercise on cardiovascular mortality were not modified by chronic exposure to particulate matter 2.5. Inactive participants with high particulate matter 2.5 exposure exhibited a 123% higher risk of cardiovascular death than high-exercise-group participants exposed to low levels of particulate matter 2.5 (95% CI=89, 163).

CONCLUSIONS

High level of habitual exercise combined with low exposure level of ambient particulate matter 2.5 is associated with the lowest risk of cardiovascular death. A higher level of habitual exercise is associated with a lower risk of cardiovascular death at all levels of particulate matter 2.5 exposure studied. The results indicate that habitual exercise is a safe health promotion strategy even for people residing in relatively polluted regions.

Patient and Public Involvement and Engagement (PPIE): first steps in the process of the engagement in research projects in Brazil

Patient and Public Involvement and Engagement (PPIE) – sometimes called Community Engagement and Involvement (CEI) – comes as a big challenge but one that can be very helpful for health care professionals and stakeholders in planning better health policies for attending to the main needs of the community. PPIE involves three pillars: public involvement, public engagement, and participation. Public involvement occurs when members of the general population are actively involved in developing the research question, designing, and conducting the research. Public engagement tells people about new studies, why they are important, the impact of results, the possible implication of the main findings for the community, and the possible impact of these new findings in society, as well as, in the dissemination of knowledge to the general population. Participation is being a volunteer in the study. Our experience with PPIE, to the best of our knowledge the first initiative in Brazil, is a partnership with the University of Birmingham, the University of Liverpool, and the NIHR Global Health Group on Atrial Fibrillation (AF) Management focusing on the AF care pathway exploring the important aspects of diagnosis and treatment in the primary care system from a low-middle income area in São Paulo. The involvement of patients/public in the research represents a new step in the process of inclusion of all segments of our society based on patient illness and the gaps in knowledge aiming to open new horizons for continuous improvement and better acceptance of research projects.

Association between atrial high rate episode burden and autonomic and vascular function in patients with implanted cardiac device

Background

Patients who experience frequent atrial high rate episodes (AHREs), recorded on implantable cardiac devices, are at an increased risk of stroke and systemic embolism. Increased duration of AHRE is related to higher risk of thromboembolic event. The underlying pathophysiology is unclear; however, autonomic and/or endothelial dysfunction may contribute.

Purpose

We tested the hypothesis that patients with high AHRE burden have worse autonomic and vascular function compared to patients with low AHRE burden.

Design

We studied 44 patients split in two groups: high AHRE burden (longest AHRE ≥24 hours; n=22) and low AHRE burden (longest AHRE <24 hours; n=22). Resting time- and frequency-domain measures of HRV were determined to index cardiac autonomic function. High-resolution ultrasound was used to measure brachial artery diameter at rest and during reactive hyperaemia (endothelium-dependent flow mediated dilation (FMD)).

Results

FMD was higher in the low AHRE burden group compared to high AHRE group (5.5% [95% confidence interval (CI):3.4–7.6] vs 3.1% [95% CI: 1.9–6.2]; p=0.04) (table 1). Mean heart rate (p<0.001) and AHRE burden (p=0.02) were independent predictors of FMD on multivariate analysis. Time-domain, frequency-domain and non-linear indices of HRV were not significantly different between the groups. A slower heart rate (Spearman's rho 0.369; p=0.01) and high AHRE burden (Spearman's rho −0.315; p=0.04) were independently associated with changes seen on FMD following adjustment for multiple variables (p=0.001 and p=0.03 respectively).

Conclusion

Endothelium-dependent FMD is impaired in patients with high AHRE burden, while HRV derived indices of autonomic function were not affected by AHRE burden. Endothelial dysfunction may play an important role in the adverse outcomes seen in patients who experience frequent AHRE.

Funding Acknowledgement

Type of funding sources: None.

Risk of cardiovascular outcomes among women with endometriosis in the United Kingdom: a retrospective matched cohort study

OBJECTIVE

To describe the prevalence and incidence of endometriosis and to estimate the risk of cardiovascular outcomes in women with endometriosis.

DESIGN

Population-based cohort study using The Health Improvement Network database.

SETTING

UK primary care.

POPULATION

Women aged 16-50 years were followed from 1995 to 2018.

METHODS

Adjusted hazard ratios (aHR) for cardiovascular outcomes comparing women with endometriosis with those without endometriosis were estimated using multivariable Cox regression models. Prevalence and incidence of endometriosis were estimated using annual (1998-2017) sequential cross-sectional and cohort studies, respectively.

MAIN OUTCOME MEASURE

The primary outcome was composite cardiovascular disease (CVD) including, ischaemic heart disease (IHD), heart failure (HF) and cerebrovascular disease. Secondary outcomes were arrhythmia, hypertension and all-cause mortality.

RESULTS

In all, 56 090 women with endometriosis and 223 669 matched controls without endometriosis were included in the analysis of cardiovascular risk. Compared with women without endometriosis, the aHR for cardiovascular outcomes among women with endometriosis were: composite CVD 1.24 (95% CI 1.13-1.37); IHD 1.40 (95% CI 1.22-1.61); cerebrovascular disease 1.19 (95% CI 1.04-1.36); HF 0.76 (95% CI 0.54-1.07); arrhythmia 1.26 (95% CI 1.11-1.43); hypertension 1.12 (95% CI 1.07-1.17) and all-cause mortality 0.66 (95% CI 0.59-0.74). The incidence of endometriosis was 12.3 per 10 000 person-years in 1998 and 11.5 per 10 000 person-years in 2017. The prevalence of endometriosis increased from 119.7 per 10 000 population in 1998 to 201.3 per 10 000 population in 2017.

CONCLUSION

Endometriosis is associated with an increased risk of cardiovascular outcomes. Young women with endometriosis are a potential target for CVD risk assessment and prevention.

TWEETABLE ABSTRACT

Endometriosis is associated with increased risk of cardiovascular outcomes: a UK retrospective matched cohort study.

Impact of obesity and metabolic health status in the development of non-alcoholic fatty liver disease (NAFLD): A United Kingdom population-based cohort study using the health improvement network (THIN)

BACKGROUND

With the obesity epidemic reaching crisis levels, there has been attention around those who may be resilient to the effects of obesity, termed metabolically healthy obesity (MHO), who initially present without associated metabolic abnormalities. Few longitudinal studies have explored the relationship between MHO and non-alcoholic fatty liver disease (NAFLD), which we address using over 4 million primary care patient records.

METHODS

A retrospective population-based longitudinal cohort was conducted using The Health Improvement Network (THIN) database incorporating adults with no history of NAFLD or alcohol excess at baseline. Individuals were classified according to BMI category and metabolic abnormalities (diabetes, hypertension and dyslipidaemia). Diagnosis of NAFLD during follow-up was the primary outcome measure. NAFLD was identified by Read codes.

RESULTS

During a median follow-up period of 4.7 years, 12,867 (0.3%) incident cases of NAFLD were recorded in the cohort of 4,121,049 individuals. Compared to individuals with normal weight and no metabolic abnormalities, equivalent individuals who were overweight, or obese were at significantly greater risk of incident NAFLD (Adjusted HR 3.32 (95%CI 2.98-3.49), and 6.92 (6.40-7.48, respectively). Metabolic risk factors further increased risk, including in those with normal weight and 1 (2.27, 1.97-2.61) or = < 2 (2.39, 1.99-2.87) metabolic abnormalities.

CONCLUSIONS

MHO individuals are at greater risk of developing NAFLD compared to those with normal weight. This finding supports that the MHO phenotype is a temporary state, and weight must be considered a risk factor even before other risk factors develop. Being normal weight with metabolic abnormalities was also associated with risk of NAFLD.

The double burden of malnutrition among adolescents: analysis of data from the Global School-Based Student Health and Health Behavior in School-Aged Children surveys in 57 low- and middle-income countries

Background

Adults and young children in countries experiencing the nutrition transition are known to be affected simultaneously by undernutrition and overnutrition. Adolescence is a critical period for growth and development. Yet, it is unknown to what extent this double burden of malnutrition affects adolescents in low- and middle-income countries (LMICs) and the macrolevel contextual factors associated with the double burden of malnutrition.

Objective

The aim was to quantify the magnitude of the double burden of malnutrition among adolescents and to examine the potential sources of heterogeneity in prevalence estimates across LMICs.

Design

We used individual-participant data from the Global School-Based Student Health and Health Behavior in School-Aged Children surveys conducted in 57 LMICs between 2003 and 2013, comprising 129,276 adolescents aged 12-15 y. Pooled estimates of stunting, thinness, or both; overweight or obesity; and concurrent stunting and overweight or obesity were calculated overall, by regions, and stratified by sex, with random-effects meta-analysis. Guided by UNICEF's conceptual framework for child malnutrition, we used ecological linear regression models to examine the association between macrolevel contextual factors (internal conflict, lack of democracy, gross domestic product, food insecurity, urbanization, and survey year) and stunting, thinness, and overweight and obesity prevalence, respectively.

Results

The prevalence of stunting was 10.2% (95% CI: 8.3%, 12.2%) and of thinness was 5.5% (95% CI: 4.3%, 6.9%). The prevalence of overweight or obesity was 21.4% (95% CI: 18.6%, 24.2%). Between 38.4% and 58.7% of the variance in adolescent malnutrition was explained by macrolevel contextual factors. The prevalence of concurrent stunting and overweight or obesity was 2.0% (95% CI: 1.7%, 2.5%).

Conclusions

The double burden of malnutrition among adolescents in LMICs is common. Context-sensitive implementation and scale-up of interventions and policies for the double burden of malnutrition are needed to achieve the Sustainable Development Goal to end malnutrition in all of its forms by 2030. This trial was registered at clinicaltrials.gov as NCT03346473.

Adiposity and incident diabetes within 4 years of follow-up: the Guangzhou Biobank Cohort Study

AIM

Whether different adiposity measures predict incident diabetes differentially in general Chinese populations is unclear. We investigated this in Chinese people aged 50+ years in the Guangzhou Biobank Cohort Study.

METHODS

Waist circumference and BMI were measured at baseline, and fasting glucose was measured at both baseline and follow-up examinations. Incident diabetes was defined as fasting glucose ≥ 7.0 mmol/l, glucose after 2-h oral glucose tolerance test ≥ 11.1 mmol/l, and/or self-reported physician-diagnosed diabetes during the follow-up period.

RESULTS

Of 15 752 people without diabetes at baseline from 2003 to 2008, 1779 (11.3%) developed incident diabetes during the follow-up from 2008 to 2012 (mean = 3.6 years, sd = 1.0). After mutually adjusting each other and adjusting for other potential confounders, waist circumference showed a higher predictive value than BMI. The odds ratio (OR) (95% confidence interval (CI) was 1.50 (95% CI 1.37-1.64) for a 1 sd increment in waist circumference and 1.21 (95% CI 1.11-1.33), for a 1 sd increment in BMI. Similarly, after mutual adjustment, abdominal obesity was associated with an almost twofold odds of incident diabetes (OR 1.93, 95% CI 1.71-2.17), which was higher than that for general obesity (OR 1.76, 95% CI 1.50-2.06). The area under receiver operating characteristic curve (AUC) for waist circumference was higher than that for BMI [AUC = 0.676 (95% CI 0.660-0.686) vs. 0.665 (95% CI 0.651-0.678), P = 0.02].

CONCLUSION

Abdominal obesity predicted incident diabetes in older people better than general obesity. Our findings may be an early warning signal for local government or public health practitioners to develop and investigate more effective intervention programmes for diabetes, and should also be disseminated to the public to pay more attention to this important public health issue.

Outcomes of levator advancement and Müller muscle-conjunctiva resection for the repair of upper eyelid ptosis

Both the Müller muscle-conjunctiva resection (MMCR) and levator advancement (LA) procedures can be used to manage ptosis in patients with good levator function. The aim of this article is to evaluate the efficacy and cosmetic outcomes of the two procedures. The clinical records of 29 consecutive eyelids of 26 patients undergoing MMCR and 30 eyelids of 23 patients undergoing LA were analysed. Eleven (42%) in the LA group and 9 (39%) in the MMCR group were male. The preoperative eyelid measurements were significantly different in the LA compared to the MMCR groups, in terms of palpebral aperture (PA) (6.3 vs 7.4, p = 0.01), marginal reflex distance 1 (MRD1) (-0.1 vs 1.5, p < 0.001) and levator function (LF) (12.1 vs 13.4, p = 0.03). The MRD1 1 month post-surgery was slightly less in the LA group compared to the MMCR group (2.6 vs 3.18 mm, p = 0.047) but not significantly different at months 3 and 6. The final change in MRD1 was significantly higher in the LA group (2.93 vs 1.76, p = 0.004). The MMCR group had a lower incidence of lid contour abnormalities (0% vs 20%, p = 0.01) and overcorrection (0% vs 13%, p = 0.04). There was no statistically significant difference in the rates of undercorrection in either group. Both the MMCR as well as LA procedures are effective for mild to moderate ptosis in patients with good levator function. Patients undergoing MMCR had higher success rates, better preservation of the natural lid contour, and a lower incidence of overcorrection than patients undergoing LA.

Effect of obstructive sleep apnoea on diabetic retinopathy and maculopathy: a systematic review and meta-analysis

AIMS

To summarize the association between obstructive sleep apnoea and diabetic retinopathy and diabetic maculopathy, and to examine the effects of oxygen desaturation index, mean and minimum oxygen saturation and time spent with < 90% oxygen saturation on diabetic retinopathy and diabetic maculopathy.

METHODS

A systematic search was performed for papers published from inception to January 2014 in MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews using indexed terms and free text. Additional searches were carried out for grey literature. Two authors conducted the study selection and quality assessment. Data extraction was performed by the main author and checked by the other authors.

RESULTS

One cohort study and 15 cross-sectional studies were included for narrative synthesis and three for meta-analyses. There was no convincing evidence that obstructive sleep apnoea was associated with diabetic retinopathy, although some evidence suggested that obstructive sleep apnoea was associated with greater severity of diabetic retinopathy and advanced diabetic retinopathy in people with Type 2 diabetes. Only six studies examined the impact of obstructive sleep apnoea on diabetic maculopathy and our narrative review suggests there is an association in Type 2 diabetes. Oxygen desaturation index, mean oxygen saturation or time spent with < 90% oxygen saturation were not associated with diabetic retinopathy, and insufficient evidence was available to draw conclusions on their effects on diabetic maculopathy; however, there was evidence from both narrative synthesis and meta-analysis that minimum oxygen saturation had an impact on diabetic retinopathy (pooled odds ratio 0.91, 95% CI 0.87-0.95; I(2) = 0%).

CONCLUSIONS

There is a need for large cohort studies with long-term follow-up data to examine the long-term effects of obstructive sleep apnoea and other sleep variables on advanced retinal disease in diabetes.

Glycaemia is associated with cognitive impairment in older adults: the Guangzhou Biobank Cohort Study

AIMS

an association between T2DM and cognitive impairment has been reported among Western populations, but data are limited in other settings. We investigated the cross-sectional association between fasting blood glucose (FBG) and cognition in an older Chinese population.

METHODS

the Guangzhou Biobank Cohort Study included 27,971 individuals (50-96 years, mean age 61.5 years, 72% female) with measures of cognitive function assessed using modified Delayed Word Recall Test (DWRT) and Mini-Mental State Examination (MMSE). Fasting glucose and lipids, and potential confounders were measured.

RESULTS

after adjustment for potential confounders, the risk for cognitive impairment as measured by DWRT, significantly increased [odds ratio (OR) = 1.18, 95% CI 1.00-1.40] but the association was of borderline significance when measured by MMSE (OR = 1.04, 95% CI 0.73-1.47) in those with diabetes relative to those without diabetes. Fasting blood glucose was significantly negatively associated with cognitive function as measured by DWRT but not MMSE, with an increase of 1 mmol/l of FBG associated with a decrease of 0.02 in DWRT (P < 0.05, 95% CI -0.03 to -0.002) and 0.03 in MMSE score (P = 0.114, 95% CI -0.06-0.01).

CONCLUSIONS

an FBG level indicative of T2DM was associated with increased risk for cognitive impairment. The findings also demonstrate that glycaemia is continuously associated with cognitive impairment, suggesting that dysfunction is associated with increasing glucose levels even in the normoglycaemic range.

The complexity of obesity in U.K. adolescents: relationships with quantity and type of technology, sleep duration and quality, academic performance and aspiration

BACKGROUND

Contemporary technology and multiple device use may link to increased body mass index (BMI). The sleep-obesity relationship is inconsistent in adolescents. Sleep duration and quality may have crucial connections to obesity development, particularly in adolescents where sleep alterations are common. Elevated BMI in adolescents may influence academic performance and aspiration, but data are limited.

OBJECTIVES

The objectives of this study was to assess the linear associations between BMI z-score and (i) quantity/type of technology used; (ii) sleep quantity/quality and (iii) academic performance/aspiration.

METHODS

Consenting adolescents (n = 624; 64.9% girls, aged 11-18 years) were recruited. The Schools Sleep Habits Survey and Technology Use Questionnaire were administered. Objective measures of height/weight were obtained.

RESULTS

Quantity of technology was positively associated with BMI z-score β = 0.10, P < 0.01. Those who always engaged in video gaming had significantly higher BMI z-score vs. never-users, β = 1.00, P < 0.001. Weekday sleep duration and sleep onset latency were related to BMI z-score, β = -0.24, P < 0.001 and β = 0.01, P < 0.001, respectively. An inverse linear association was observed between BMI z-score and academic performance, β = -0.68, P < 0.001.

CONCLUSIONS

If confirmed prospectively, reducing bedtime use of technology and improving sleep hygiene in adolescents could be an achievable intervention for attenuating obesity with potentially positive effects on academic performance.

Genome-wide association study in a Chinese population identifies a susceptibility locus for type 2 diabetes at 7q32 near PAX4

AIMS/HYPOTHESIS

Most genetic variants identified for type 2 diabetes have been discovered in European populations. We performed genome-wide association studies (GWAS) in a Chinese population with the aim of identifying novel variants for type 2 diabetes in Asians.

METHODS

We performed a meta-analysis of three GWAS comprising 684 patients with type 2 diabetes and 955 controls of Southern Han Chinese descent. We followed up the top signals in two independent Southern Han Chinese cohorts (totalling 10,383 cases and 6,974 controls), and performed in silico replication in multiple populations.

RESULTS

We identified CDKN2A/B and four novel type 2 diabetes association signals with p < 1 × 10(-5) from the meta-analysis. Thirteen variants within these four loci were followed up in two independent Chinese cohorts, and rs10229583 at 7q32 was found to be associated with type 2 diabetes in a combined analysis of 11,067 cases and 7,929 controls (p meta = 2.6 × 10(-8); OR [95% CI] 1.18 [1.11, 1.25]). In silico replication revealed consistent associations across multiethnic groups, including five East Asian populations (p meta = 2.3 × 10(-10)) and a population of European descent (p = 8.6 × 10(-3)). The rs10229583 risk variant was associated with elevated fasting plasma glucose, impaired beta cell function in controls, and an earlier age at diagnosis for the cases. The novel variant lies within an islet-selective cluster of open regulatory elements. There was significant heterogeneity of effect between Han Chinese and individuals of European descent, Malaysians and Indians.

CONCLUSIONS/INTERPRETATION

Our study identifies rs10229583 near PAX4 as a novel locus for type 2 diabetes in Chinese and other populations and provides new insights into the pathogenesis of type 2 diabetes.

Impact of metabolic syndrome on ischemic heart disease - a prospective cohort study in an Iranian adult population: Isfahan Cohort Study

BACKGROUND

The impact of the metabolic syndrome among populations in the Middle East region is unknown; we therefore examined the association between the syndrome and the risk of ischemic heart disease (IHD) in an Iranian population.

METHODS AND RESULTS

The Isfahan Cohort Study (ICS) prospectively followed 6146 Iranian people (51.8% women, aged 35-75 years) from three cities and their rural districts who were initially free of ischemic heart disease. During the 5 year follow-up, 209 (56% men) cases of ischemic heart disease were detected. The metabolic syndrome was defined by the modified criteria of the National Cholesterol Education Program Adult Treatment Panel III (NCEP/ATPIII). End points were defined as fatal and nonfatal myocardial infarction, sudden cardiac death and unstable angina. A clear dose-response relationship was found between the number of metabolic risk factors and the incidence of IHD, with the hazard ratios increasing dose-dependently from 1.72 (95% CI 0.86-3.46) for only one to 1.97 (1.00-3.90), 2.85 (1.45-5.58) and 4.44 (2.25-8.76) for 2, 3 and ≥4 metabolic syndrome component respectively, relative to those with no component. The adjusted hazard ratio (95% CI) associated with the metabolic syndrome was 1.58 (1.06-2.35) in men and 1.72 (1.08-2.74) in women for IHD. The contribution of metabolic syndrome to the IHD risk was particularly strong among smokers although there was no significant interaction.

CONCLUSIONS

The metabolic syndrome by NCEP/ATPIII definition is a major determinant of ischemic heart disease in this middle-aged Iranian population, especially among smokers.

Influenza vaccination and hospitalisation in Elderly Health Centres

1. A cohort of Elderly Health Centres was examined to determine whether influenza vaccination decreased hospitalisation and mortality. 2. In the influenza season, influenza vaccination reduced all-cause mortality by half and cardiorespiratory hospitalisation by a quarter. The extent to which influenza vaccination protects older people from serious morbidity and mortality needs to be confirmed in appropriately designed studies, so that scarce health care resources can be used effectively

White blood cell subsets are associated with carotid intima-media thickness and pulse wave velocity in an older Chinese population: the Guangzhou Biobank Cohort Study

Cross-sectional associations between white blood cell (WBC) count, lymphocyte and granulocyte numbers, and carotid intima-media thickness (IMT) and brachial-ankle pulse wave velocity (PWV) were examined in a novel older Chinese community sample. A total of 817 men and 760 women from a sub-study of the Guangzhou Biobank Cohort Study had a full blood count measured by an automated hematology analyzer, carotid IMT by B-mode ultrasonography and brachial-ankle PWV by a non-invasive automatic waveform analyzer. Following adjustment for confounders, WBC count (β=0.07, P<0.001) and granulocyte (β=0.07, P<0.001) number were significantly positively related to PWV, but not lymphocyte number. Similarly, WBC count (β=0.08, P=0.03), lymphocyte (β=0.08, P=0.002) and granulocyte (β=0.03, P=0.04) number were significantly positively associated with carotid IMT, but only the association with lymphocyte count survived correction for other cardiovascular risk factors. In conclusion, higher WBC, particularly lymphocyte and granulocyte, count could be used, respectively, as markers of cardiovascular disease risk, measured through indicators of atherosclerosis and arterial stiffness. The associations for WBC count previously observed by others were likely driven by higher granulocytes; an index of systemic inflammation.

The Isfahan cohort study: rationale, methods and main findings

A 10-year longitudinal population-based study, entitled the Isfahan Cohort Study (ICS) is being conducted. The ICS commenced in 2001, recruiting individuals aged 35+ living in urban and rural areas of three counties in central Iran, to determine the individual and combined impact of various risk factors on the incidence of cardiovascular events. After 24379 person-years of follow-up with a median follow-up of 4.8 years, we documented 219 incident cases of ischemic heart disease (IHD) (125 in men and 94 in women) and 57 incident cases of stroke (28 in men and 29 in women). The absolute risk of IHD was 8.9 (7.8-10.2) per 1000 person-years for all participants, 10.6 (8.8-12.5) per 1000 person-years for men and 7.4 (6.0-9.0) per 1000 person-years for women. The respective risk of ischemic stroke was 2.3 (1.7-3.0), 2.3 (1.6-3.3) and 2.3 (1.5-3.2) per 1000 person-years. The risk of IHD was approximately 3.5-fold higher in the presence of hypertension, followed by diabetes mellitus and hypercholesterolemia with near 2.5- and twofold higher risk, respectively. This cohort provides confirmatory evidence of the ethnic differences in the magnitude of the impact of various risk factors on cardiovascular events. The differences may be due to varying absolute risk levels among populations and the existing ethnic disparities for using western risk equations to local requirements.

Part 5. Public health and air pollution in Asia (PAPA): a combined analysis of four studies of air pollution and mortality

BACKGROUND

In recent years, Asia has experienced rapid economic growth and a deteriorating environment caused by the increasing use of fossil fuels. Although the deleterious effects of air pollution from fossil-fuel combustion have been demonstrated in many Western nations, few comparable studies have been conducted in Asia. Time-series studies of daily mortality in Asian cities can contribute important new information to the existing body of knowledge about air pollution and health. Not only can these studies verify important health effects of air pollution in local regions in Asia, they can also help determine the relevance of existing air pollution studies to mortality and morbidity for policymaking and environmental controls. In addition, the studies can help identify factors that might modify associations between air pollution and health effects in various populations and environmental conditions. Collaborative multicity studies in Asia-especially when designed, conducted, and analyzed using a common protocol-will provide more robust air pollution effect estimates for the region as well as relevant, supportable estimates of local adverse health effects needed by environmental and public-health policymakers.

SPECIFIC OBJECTIVES

The Public Health and Air Pollution in Asia (PAPA*) project, sponsored by the Health Effects Institute, consisted of four studies designed to assess the effects of air pollution on mortality in four large Asian cities, namely Bangkok, in Thailand, and Hong Kong, Shanghai, and Wuhan, in China. In the PAPA project, a Common Protocol was developed based on methods developed and tested in NMMAPS, APHEA, and time-series studies in the literature to help ensure that the four studies could be compared with each other and with previous studies by following an established protocol. The Common Protocol (found at the end of this volume) is a set of prescriptive instructions developed for the studies and used by the investigators in each city. It is flexible enough to allow for adjustments in methods to optimize the fit of health-effects models to each city's data set. It provides the basis for generating reproducible results in each city and for meta-estimates from combined data. By establishing a common methodology, factors that might influence the differences in results from previous studies can more easily be explored. Administrative support was provided to ensure that the highest quality data were used in the analysis. It is anticipated that the PAPA results will contribute to the international scientific discussion of how to conduct and interpret time-series studies of air pollution and will stimulate the development of high-quality routine systems for recording daily deaths and hospital admissions for time-series analysis.

METHODS

Mortality data were retrieved from routine databases with underlying causes of death coded using the World Health Organization (WHO) International Classification of Diseases, 9th revision or 10th revision (ICD-9, ICD-10). Air quality measurements included nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with aerodynamic diameter < or = 10 microm (PM10), and ozone (O3) and were obtained from several fixed-site air monitoring stations that were located throughout the metropolitan areas of the four cities and that met the standards of procedures for quality assurance and quality control carried out by local government units in each city. Using the Common Protocol, an optimized core model was established for each city to assess the effects of each of the four air pollutants on daily mortality using generalized linear modeling with adjustments for time trend, seasonality, and other time-varying covariates by means of a natural-spline smoothing function. The models were adjusted to suit local situations by correcting for influenza activity, autocorrelation, and special weather conditions. Researchers in Hong Kong, for example, used influenza activity based on frequency of respiratory mortality; researchers in Hong Kong and Shanghai used autoregressive terms for daily outcomes at lag days; and researchers in Wuhan used additional smoothing for periods with extreme weather conditions.

RESULTS AND DISCUSSION

For mortality due to all natural (nonaccidental) causes at all ages, the effects of air pollutants per 10-microg/m3 increase in concentration was found to be higher in Bangkok than in the three Chinese cities, with the exception of the effect of NO2 in Wuhan. The magnitude of the effects for cardiovascular and respiratory mortality were generally higher than for all natural mortality at all ages. In addition, the effects associated with PM10 and O3 in all natural, cardiovascular; and respiratory mortality were found to be higher in Bangkok than in the three Chinese cities. The explanation for these three findings might be related to consistently higher daily mean temperatures in Bangkok, variations in average time spent outdoors by the susceptible populations, and the fact that less air conditioning is available and used in Bangkok than in the other cities. However, when pollutant concentrations were incorporated into the excess risk estimates through the use of interquartile range (IQR), the excess risk was more comparable across the four cities. We found that the increases in effects among older age groups were greater in Bangkok than in the other three cities. After excluding data on extremely high concentrations of PM10 in Bangkok, the effect estimate associated with PM10 concentrations decreased in Bangkok (suggesting a convex relationship between risk and PM10, where risk levels off at high concentrations) instead of increasing, as it did in the other cities. This leveling off of effect estimates at high concentrations might be related to differences in vulnerability and exposure of the population to air pollution as well as to the sources of the air pollutant. IMPLICATIONS OF THE STUDY: The PAPA project is the first coordinated Asian multicity air pollution study ever published; this signifies the beginning of an era of cooperation and collaboration in Asia, with the development of a common protocol for coordination, data management, and analysis. The results of the study demonstrated that air pollution in Asia is a significant public health burden, especially given the high concentrations of pollutants and high-density populations in major cities. When compared with the effect estimates reported in the research literature of North America and Western Europe, the study's effect estimates for PM10 were generally similar and the effect estimates for gaseous pollutants were relatively higher. In Bangkok, however, a tropical city where total exposures to outdoor pollution might be higher than in most other cities, the observed effects were greater than those reported in the previous (i.e., Western) studies. In general, the results suggested that, even though social and environmental conditions across Asia might vary, it is still generally appropriate to apply to Asia the effect estimates for other health outcomes from previous studies in the West. The results also strongly support the adoption of the global air quality guidelines recently announced by WHO.

A pilot double-blind randomised placebo-controlled trial of the effects of fixed-dose combination therapy ('polypill') on cardiovascular risk factors

AIM

Our objective was to investigate the effects and tolerability of fixed-dose combination therapy on blood pressure and LDL in adults without elevated blood pressure or lipid levels.

METHODS

This was a double-blind randomised placebo-controlled trial in residents of Kalaleh, Golestan, Iran. Following an 8-week placebo run-in period, 475 participants, aged 50 to 79 years, without cardiovascular disease, hypertension or hyperlipidaemia were randomised to fixed-dose combination therapy with aspirin 81 mg, enalapril 2.5 mg, atorvastatin 20 mg and hydrochlorothiazide 12.5 mg (polypill) or placebo for a period of 12 months. The primary outcomes were changes in LDL-cholesterol, systolic and diastolic blood pressure and adverse reactions. Analysis was by intention-to-treat basis.

RESULTS

At baseline, there were differences in systolic blood pressure (6 mmHg). Taking account of baseline differences, at 12 months, polypill was associated with statistically significant reductions in blood pressure (4.5/1.6 mmHg) and LDL-cholesterol (0.46 mmol/l). The study drug was well tolerated, but resulted in the modest reductions in blood pressure and lipid levels.

CONCLUSION

The effects of the polypill on blood pressure and lipid levels were less than anticipated, raising questions about the reliability of the reported compliance. There is a case for a fully powered trial of a polypill for the prevention of cardiovascular disease.

Arterial stiffness and left-ventricular diastolic dysfunction: Guangzhou Biobank Cohort Study-CVD

Brachial-ankle pulse wave velocity (baPWV), a marker of arterial stiffness, is an established cardiovascular risk factor of ventricular stiffening. We studied the association of baPWV with left-ventricular (LV) diastolic function in a sub-study of the Guangzhou Biobank Cohort Study. In all, 378 Chinese subjects with a normal ejection fraction (>50%) had baPWV measurement by a noninvasive automatic waveform analyser, carotid intima-medial thickness (IMT) measurement by B-mode ultrasonography and cardiac diastolic function assessment by echocardiography. After adjusting for age, both baPWV and IMT were associated with LV mass index, posterior wall end-diastolic thickness and inter-ventricular end-diastolic thickness, but only baPWV was associated with deceleration time, atrial flow velocity and E/A ratio. Multivariable linear regression model showed that baPWV and mean arterial pressure, but not IMT, were significantly associated with E/A ratio (β=-0.02, P=0.03 and β=-0.36, P=0.02, respectively). The receiver operator characteristic curve showed that baPWV was better than pulse pressure or mean arterial pressure to detect LV diastolic dysfunction (E/A<1.0). Our study suggested that increased baPWV might be an independent risk factor or marker for diastolic dysfunction. Early detection of an intervention on increased baPWV may be important for prevention of cardiac diastolic dysfunction.

Exercise and diet in weight management: updating what works

The world is facing major problems associated with the rapid increase in levels of overweight and obesity. Solving this problem via appropriate modifications to exercise habits and/or diet appears easy, but in practice it is inordinately difficult and only a small percentage manage to maintain their weight loss over the long term. However, a number of strategies can be used to increase the chances of success. Medical doctors, dieticians and other allied health professionals are potentially well placed to provide guidance to those at risk of overweight/obesity. This review is aimed at supporting major initiatives targeting an increase in community physical activity to help reduce the prevalence of overweight/obesity, such as the "Change4Life" campaign in the UK (http://www.nhs.uk/change4life) and the "Exercise is Medicine" campaign in the USA (http://www.exerciseismedicine.org). By providing a concise summary of the evidence-based research that can be easily understood by a wide range of health professionals, this review hopes to provide a useful document that can be used to enhance preventive counselling by promoting appropriate changes in lifestyle that will ultimately increase levels of physical activity, as well as reduce levels of overweight/obesity and other associated chronic hypokinetic conditions.

Airflow obstruction and metabolic syndrome: the Guangzhou Biobank Cohort Study

There is some evidence that chronic obstructive pulmonary disease (COPD) and metabolic syndrome may be related, perhaps through systemic inflammation, which is common to both. However, the association between the two conditions has not yet been clearly shown. The present study involved 7,358 adults aged > or =50 yrs from a population-based survey who underwent spirometry, a structured interview and measurement of fasting metabolic marker levels. Airflow obstruction (forced expiratory volume in 1 s/forced vital capacity ratio of less than the lower limit of normal) was present in 6.7%, and the International Diabetes Federation metabolic syndrome criteria were met by 20.0%. The risk of metabolic syndrome was higher in those with airflow obstruction than in those without (odds ratio (OR) 1.47; 95% confidence interval (CI) 1.12-1.92), after controlling for potential confounders. Of the five components of metabolic syndrome, only central obesity was significantly associated with airflow obstruction (OR 1.43; 95% CI 1.09-1.88) after adjusting for body mass index. A similar association was observed in both never and current smokers. In this Chinese sample, airflow obstruction was associated with metabolic syndrome, and, in particular, its central obesity component. This may help explain the increased risk of cardiovascular diseases in COPD, and so could guide future clinical practice.

Explaining coronary heart disease trends in Hong Kong: creation of a model for policy and planning

1. The largest contribution of coronary heart disease (CHD) mortality reductions was from medical treatment. 2. A smaller contribution was estimated to be due to risk factors changes. 3. Improvement of treatment uptake levels can have a substantial effect in reducing CHD mortality.

Is leg length a biomarker of childhood conditions in older Chinese women? The Guangzhou Biobank Cohort Study

OBJECTIVE

In developed western populations longer legs have been shown to be a biomarker of better early childhood conditions. It was hypothesised that in transitioning populations better childhood conditions may bring forward puberty and thus decrease leg length, counteracting the overall positive effect of a favourable childhood environment on leg growth.

DESIGN

Structural equation modelling was used to assess the interrelationship of age, education, father's job, age of menarche and leg length in a cross-sectional sample of 7273 Chinese women aged at least 50 years from the Guangzhou Biobank Cohort Study.

RESULTS

Leg length had no significant association with education or father's occupation on bivariable testing. After including age of menarche in the model, education was associated with longer legs (0.45 cm longer per 10 years of education, 95% CI 0.20 to 0.71). Education was also associated with younger age of menarche (1.21 years younger per 10 years of education, 95% CI 1.09 to 1.34), which was in turn associated with shorter legs (0.23 cm shorter per year of menarche earlier, 95% CI 0.18 to 0.27).

CONCLUSIONS

In older Chinese women leg length is not a universal biomarker of childhood conditions, when proxied by her educational level and father's occupation. Nutritionally driven epigenetic influences operating over generations may constrain growth in very recently developed populations. Given the impact of childhood conditions on health, and the dearth of long-term records outside the industrialised world, a greater understanding of the influences on growth in the developing world is required.

Passive smoking exposure and risk of COPD among adults in China: the Guangzhou Biobank Cohort Study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality in China, where the population is also exposed to high levels of passive smoking, yet little information exists on the effects of such exposure on COPD. We examined the relation between passive smoking and COPD and respiratory symptoms in an adult Chinese population.

METHODS

We used baseline data from the Guangzhou Biobank Cohort Study. Of 20 430 men and women over the age of 50 recruited in 2003-06, 15,379 never smokers (6497 with valid spirometry) were included in this cross-sectional analysis. We measured passive smoking exposure at home and work by two self-reported measures (density and duration of exposure). Diagnosis of COPD was based on spirometry and defined according to the GOLD guidelines.

FINDINGS

There was an association between risk of COPD and self-reported exposure to passive smoking at home and work (adjusted odds ratio 1.48, 95% CI 1.18-1.85 for high level exposure; equivalent to 40 h a week for more than 5 years). There were significant associations between reported respiratory symptoms and increasing passive smoking exposure (1.16, 1.07-1.25 for any symptom).

INTERPRETATION

Exposure to passive smoking is associated with an increased prevalence of COPD and respiratory symptoms. If this association is causal, we estimate that 1.9 million excess deaths from COPD among never smokers could be attributable to passive smoking in the current population in China. Our findings provide strong evidence for urgent measures against passive smoking in China.

Parity and the metabolic syndrome in older Chinese women: the Guangzhou Biobank Cohort Study

OBJECTIVE

To examine whether parity or gravidity contributes to the development of the metabolic syndrome (MS).

METHODS

The first phase of the Guangzhou Biobank Cohort Study recruited 7352 women and 3065 men aged 50-93 years in 2003-4. Data on the number of live births and pregnancies, other reproduction-associated factors and socioeconomic and lifestyles factors were collected by standardized interview. The MS components were determined through physical examination and measurement of fasting blood samples. MS was identified if waist circumference was >or= 90 cm for men or >or= 80 cm for women, plus any two of: (a) raised triglyceride (TG) level (1.7 mmol/l) or specific treatment for this lipid abnormality; (b) reduced high density lipoprotein (HDL)-cholesterol (< 1.03 mmol/l in males or < 1.29 mmol/l in females) or specific treatment for this lipid abnormality; (c) raised blood pressure (BP, systolic BP >or= 130 mmHg or diastolic BP >or= 85 mmHg) or hypertension therapy; and (d) raised fasting glucose (>or= 5.6 mmol/l) or previously diagnosed type 2 diabetes.

RESULTS

Before adjustment for potential confounders, we found associations between the number of births and lifestyle and socioeconomic factors in both sexes. However, in women, but not in men, body mass index (BMI), waist-hip ratio, triglyceride and glucose were positively associated with the number of birth after adjusting for a range of potential confounders. The age-adjusted prevalence of the MS increased with the number of births and pregnancies in women, but the gradient for birth was steeper than that for pregnancies [odds ratio change per birth 1.16, 95% confidence interval (CI) 1.11-1.22, P < 0.001; odds ratio change per pregnancy 1.11, 95% CI 1.06-1.16, P < 0.001], although attenuating the association adjustment did not affect the significance of these findings. There was no association in men with regard to the number of their partners' live births given the same analysis and similar shared living background with the women.

CONCLUSION

Higher parity or gravidity was associated with a consistent increase in the risk of MS in Chinese women. As the association persisted after adjustment for lifestyle factors and there was no association between the risk of MS and the number of births associated with the partners of the males, the association in women may represent a biological response to pregnancy.

Association of smoking with increasing vascular involvement in type 2 diabetic Chinese patients

PURPOSE

To identify the relationship between smoking and the metabolic profile and existing vascular disease in Chinese type 2 diabetic patients.

METHODS

1710 diabetic patients were screened for complications, and biochemical and anthropometric vascular risk factors. As most smokers were male, differences were only compared between male current (n = 196) and never smoking patients (n = 300).

RESULTS

The smokers had higher glycosylated haemoglobin levels (8.2 +/- 2.0 vs. 7.6 +/- 1.8%, p < 0.001) than never smokers, despite a greater proportion receiving hypoglycaemic agents (87.5 vs. 79.6%, p = 0.003). Male smokers compared to never smokers had lower HDL-cholesterol levels (1.12 +/- 0.31 vs. 1.20 +/- 0.30 mmol/L, p = 0.006), and elevated albumin-to-creatinine ratio (3.57 [2.68-4.75] vs. 2.47 [1.99-3.05] mg/mmol, p = 0.040). However, diastolic blood pressure was lower in the smoking group (78 +/- 12 vs. 82 +/- 12 mmHg, p = 0.001) even though they received less blood pressure-lowering treatments (23.8 vs. 33.2%, p = 0.034). The prevalence of peripheral vascular disease was increased in the diabetic patients who smoked compared to nonsmokers (7.1 vs. 2.8%, p = 0.039).

CONCLUSIONS

Smoking was associated with a more adverse metabolic profile and peripheral vascular disease. As mainland China undergoes rapid modernisation and urbanisation, the observed effects of smoking means tobacco control becomes increasingly important to prevent or minimise potential health impacts and chronic disease.

A survey of Chinese herbal medicine intake amongst preoperative patients in Hong Kong

We have surveyed, by means of a questionnaire, the preoperative use of traditional Chinese medicines in 259 adult Chinese patients admitted to a Hong Kong teaching hospital. The spectrum and use of herbal remedies differed from that reported by Western sources. Of those patients surveyed 90% used Chinese herbs on a regular daily basis in traditional soups and teas while 44% had consulted a traditional Chinese medicine practitioner in the last twelve months prior to admission, but mainly for health promotion (59%) and minor ailments (30%). Only 25% sought advice for their current illness and 13% were taking regular traditional Chinese medicines prior to admission. The ingredients were difficult to identify. Patients with cancer were more likely to use ling zhi (odds ratio 5.4). Female patients with reproductive problems were more likely to visit a traditional Chinese medical practitioner (odds ratio 2.6) and use ginseng (odds ratio 5.1). The anaesthetic implications of preoperative traditional Chinese medicine in keeping with Hong Kong practices need to be investigated, and appropriate anaesthetic guidelines should be developed.

Albuminuria is a marker of increasing intracranial and extracranial vascular involvement in Type 2 diabetic Chinese patients

AIMS/HYPOTHESIS

Albuminuria has been reported to be a marker of cardiovascular risk factors and disease morbidity and mortality, but its relationship with intracerebral atherosclerotic disease is less clear. The aim of this study was to investigate the association between albuminuria and intracranial and extracranial vascular involvement in Chinese Type 2 diabetic patients.

METHODS

The anthropometric and fasting biochemical measurements of 966 Type 2 diabetic patients with normoalbuminuria (55.6%), microalbuminuria (27.7%) or macroalbuminuria (16.7%) were compared. The prevalence of microvascular and macrovascular disease and middle cerebral artery (MCA) stenosis, measured by transcranial Doppler ultrasound, were also compared between the groups.

RESULTS

Albuminuria was closely associated with a range of adverse parameters, including high BP, dyslipidaemia, smoking and adiposity (all p<0.01). The prevalence of microvascular disease (retinopathy p<0.001) and macrovascular disease (peripheral vascular disease p=0.012, myocardial infarction, p=0.004, MCA stenosis p<0.001) increased significantly with increasing levels of albuminuria. Albuminuria was also found to be an independent predictor of microvascular and macrovascular disease.

CONCLUSIONS/INTERPRETATION

Albuminuria was an independent predictor of increasing levels of vascular risk factors and microvascular and macrovascular disease in this group of Type 2 diabetic patients, and a possible role for albuminuria as a marker of intracranial cerebrovascular disease should be further investigated.

Peripheral vascular disease in Type 2 diabetic Chinese patients: associations with metabolic indices, concomitant vascular disease and genetic factors

AIMS

Conventional and genetic risk factors have been reported to play a role in the pathogenesis of vascular disease, but do not explain the lower burden of cardiac and peripheral vascular disease (PVD) in Chinese compared with Caucasians. The role of renin-angiotensin system (RAS) gene polymorphisms and conventional vascular risk factors has not been determined.

METHODS

A total of 3097 Chinese diabetic subjects were screened for PVD, which was identified in 194 of the 2967 patients with Type 2 diabetes. Biochemical parameters and the genotype and allele frequencies of three RAS gene polymorphisms, the angiotensin-converting enzyme (ACE) insertion/deletion, angiotensinogen (AGT) M235T and angiotensin II type 1 receptor (AT1R) A1166C polymorphisms were then compared between the PVD patients and 1046 age, gender and diabetes duration-matched patients without PVD.

RESULTS

PVD identified in 6.5% was associated with significantly worse glycaemic control, lipid profile and renal function. Smoking was more common, as were the other macro- and microvascular diseases. The prevalence of hypertension was similar between the groups, yet diastolic blood pressure was slightly lower in the PVD group. The ACE D allele was significantly more frequent in patients with PVD compared with the matched diabetic controls (38.1 vs. 29.8%, P = 0.039). No differences in the AT1R or AGT polymorphisms were observed.

CONCLUSIONS

PVD was associated with a worse metabolic profile and greater concomitant vascular disease than controls. The ACE I/D polymorphism was associated with PVD in these Type 2 diabetic patients.

APOA5-1131T>C polymorphism is associated with triglyceride levels in Chinese men

A new apolipoprotein gene, APOA5, was recently discovered near the APOA1/C3/A4 gene cluster. Transgenic mice overexpressing the homologous gene, apoa5, showed reduced plasma triglyceride levels, while knockout mice had greatly increased triglycerides, suggesting that human genetic variants affecting expression of the protein product, APOAV, might affect triglyceride levels. Polymorphisms in the APOA5 gene were indeed found to be associated with triglyceride levels in men, though not in women. We sought to confirm the association of the APOA5-1131T>C polymorphism with triglyceride levels in 167 Chinese men chosen for having either high (>/=1.7 mm, n = 82) or low (</=1.2 mm, n = 85) triglycerides. More subjects with high triglycerides had one or two copies of the minor (C) allele of the polymorphism (67%) than did low triglyceride subjects (48%), and combining all subjects showed that those with one or two C alleles had higher triglyceride levels [1.67 +/- 2.20 (geometric mean +/- SD)] than those without (1.22 +/- 2.08 mm, p = 0.01), confirming the reported effect in a different ethnic group. The C allele is more common in Chinese than in Caucasians (26-40% vs. 8% of alleles), suggesting that the impact of this polymorphism on triglyceride levels in the population and therefore on public health is greater among Chinese.

Obesity and cardiovascular risk factors in Hong Kong Chinese

The purpose of this cross-sectional study was to examine the risk associations between obesity indexes [body mass index (BMI) and waist circumference (WC)], cardiovascular risk factors [plasma glucose and lipids, blood pressure and urinary albumin excretion (UAE)] and morbidity conditions (Type 2 diabetes mellitus, hypertension, dyslipidaemia and/or albuminuria) in Hong Kong Chinese. Seven-hundred and two Hong Kong Chinese subjects (18-65 years of age, 59.4% of whom had at least one morbidity condition) were recruited from the Prince of Wales Hospital, Hong Kong SAR. The measurements taken of the subjects included: height; weight; waist and hip circumferences; blood pressure; fasting plasma glucose and lipids; and 24-h UAE. The mean BMI was 22.4 and 25.7 kg m(-2) in healthy subjects and patients, respectively. The mean WC measurements of healthy subjects and patients were 77.1 and 86.4 cm in males and 71.0 and 81.8 cm in females, respectively. There were increasing trends between obesity indexes and the severity of cardiovascular risk factors and the prevalence of morbidity conditions (all P-values for trend <0.05). Using 19.0-20.9 kg m(-2) and <70 cm as a referent, subjects with a BMI of > or =25.0 kg m(-2) (in both sexes) and/or a WC of > or =85 cm in males and > or =75 cm in females had an age-adjusted odds ratio between 3.2 and 4.4 for the occurrence of at least one morbidity condition. Patients with a greater number of comorbidities also had higher BMI and WC measurements (all P-values for the trend were <0.05 with adjustment for age and gender). Hence, despite Hong Kong Chinese being less obese than Caucasians, the intimate relationships among obesity, cardiovascular risk factors and morbidity conditions remain. Our data support using lower BMI and WC levels to define obesity and its associated health risks rather than using the criteria established from Caucasians who generally have larger body frames.

Long-term improvement in homocysteine levels and arterial endothelial function after 1-year folic acid supplementation

PURPOSE

Hyperhomocysteinemia, a risk factor for atherosclerosis, is associated with endothelial dysfunction that can be improved with short-term folic acid supplementation. The current study aimed to assess whether folic acid supplementation could produce longer-term improvements in homocysteine levels and arterial endothelial function.

SUBJECTS AND METHODS

Twenty-nine healthy adults with hyperhomocysteinemia were selected from 89 volunteers enrolled in a community-based atherosclerosis screening project. All subjects were given folic acid (10 mg/d) for 1 year. Fasting plasma homocysteine levels were measured by high-performance liquid chromatography. Arterial endothelial function was measured as flow-mediated dilation of the brachial artery using high-resolution B-mode ultrasound.

RESULTS

Folic acid supplementation for 1 year was associated with a significant increase in mean (+/-SD) plasma folate levels (24 +/- 5 nmol/L to 40 +/- 5 nmol/L; P < 0.001) and a significant decline in homocysteine levels (9.0 +/- 1.7 micromol/L to 7.9 +/- 2.0 micromol/L; P < 0.001). Flow-mediated dilation also improved significantly, from 7.4% +/- 2.0% to 8.9% +/- 1.5% (P <0.0001), but there was no change in nitroglycerin-induced (endothelium-independent) responses.

CONCLUSIONS

These results demonstrate that long-term folic acid improves arterial endothelial function and has potential implications for the prevention of atherosclerosis in adults with hyperhomocysteinemia.

Accelerated atherosclerosis in patients with systemic lupus erythematosus: a review of the causes and possible prevention

Systemic lupus erythematosus is an autoimmune disorder affecting multiple organ systems. Patients with systemic lupus erythematosus exhibit a bimodal pattern of mortality, with those who have had the disease for 5 to 10 years being at increased risk of cardiovascular disease, particularly myocardial infarction. Elevated levels of conventional cardiovascular risk factors promote vascular damage resulting in impairment of normal endothelial function. In addition, autoantibodies directed against oxidised lipoproteins, along with chronic secretion of inflammatory cytokines and suppression of fibrinolytic parameters, are thought to increase atherogenesis. Treatment with corticosteroids may also contribute to the accelerated atherosclerosis observed in these patients. This review discusses the accentuated relationship between conventional cardiovascular risk factors, systemic lupus erythematosus-induced inflammatory changes and the early stages of atherogenesis and how careful monitoring of risk factors and use of appropriate therapies may reduce the progression of atheroma development in patients with systemic lupus erythematosus.

Factor analysis of the metabolic syndrome: obesity vs insulin resistance as the central abnormality

OBJECTIVES

To evaluate whether there is one central abnormality contributing to the conditions associated with the metabolic syndrome (MES), or whether one abnormality is contributing on multiple levels.

METHODS

We recruited 145 Chinese subjects aged 17-68 y with varying degrees of insulin-sensitivity (IS): 33 healthy, 59 with type 2 diabetes mellitus, 32 essential hypertensives and 21 dyslipidaemics. IS was evaluated by the short insulin sensitivity test using a 0.1 U/kg intravenous bolus dose of insulin. Blood pressure, anthropometric measures and biochemical parameters associated with IS were also measured. Exploratory factor analyses (EFA) were performed in the entire group of 145 subjects and in the 76 with normal glucose tolerance.

RESULTS

EFA in all 145 subjects defined three distinct, independent factors. Factor 1 was interpreted as general and central adiposity, impaired IS and glucose intolerance, Factor 2 was associated with hypertension and general and central obesity, whilst Factor 3 was strongly related to low HDL-cholesterol and high triglyceride concentrations and weakly to waist circumference. In patients with impaired glucose tolerance, only two factors were identified; factor 1 related to reduced IS, impaired glucose tolerance, dyslipidaemia and general and central adiposity, and factor 2 which was related to blood pressure and general and central adiposity.

CONCLUSIONS

These models suggest that the clustering of variables in MES is a result of multiple factors linked by adiposity and not a single aetiology. Furthermore, increases in blood pressure are related to obesity in these Chinese subjects rather than decreased IS per se.

Relationships between the taqI polymorphism of the dopamine D2 receptor and blood pressure in hyperglycaemic and normoglycaemic Chinese subjects

BACKGROUND

We have previously reported an association of the A2 allele of the dopamine D2 receptor (DRD2) TaqI polymorphism with increased blood pressure in normoglycaemic Chinese subjects, but conversely possibly with decreased indices of obesity. Hypertension is also a common feature of patients with type 2 diabetes, with up to 50% being hypertensive.

OBJECTIVE

To compare the relationship between the DRD2 TaqI polymorphism, blood pressure and obesity in Chinese patients with and without fasting hyperglycaemia.

METHOD

The DRD2 TaqI polymorphism was determined by PCR-RFLP in 519 normoglycaemic and 471 hyperglycaemic Chinese subjects, of whom 53.2 and 48.8% were hypertensive, respectively.

RESULTS

In the normoglycaemic subjects there was a significant increase in mean arterial pressure (P= 0.041) with increasing proportions of the A2 allele, 95 +/- 16, 96 +/- 17 and 100 +/- 17 mmHg for the A1A1, A1A2 and A2A2 genotypes, respectively. However, the relationship was not observed in the subjects with fasting hyperglycaemia either in the total group or in the subgroup who were not receiving blood pressure-lowering medication (n = 383, 97 +/- 15, 98 +/- 14 and 97 +/- 15 mmHg, respectively). When the whole group was divided into those subjects obese by either body mass index or waist-to-hip ratio (n = 484) and those subjects not obese by both these criteria (n= 506), the A1 allele (49.2 vs. 43.8%, P = 0.02) and A1 allele containing genotypes (P = 0.03) were more frequent in the obese subjects. Similar relationships were seen in the normoglycaemic and hyperglycaemic groups separately, although these did not reach significance.

CONCLUSIONS

In the normoglycaemic subjects, the A2 allele was associated with increased blood pressure and possibly lower indices of obesity, but in the hyperglycaemic subjects only the possible association with obesity was noted.

[Protection against paracetamol-induced hepatic damage using total flavonoids of Astragalus]

OBJECTIVE

To study the mechanism of the protection by total flavonoids of Astragalus protection against paracetamol-induced hepatic damage.

METHOD

Analysing paracetamol and its metabolites in mice urine by HPLC and studying the mechanism of anti-damage induced by paracetamol using experiment module of pentobarbital-induced sleeping time.

RESULT

Administration of large doses of paracetamol to C57BL/6J mice produced significant hepatic injury with marked elevation in serum ALT activity and severe hepatocellular necrosis. TFA showed a good protective capability against paracetamol-induced hepatic injury. TFA had no marked effect on paracetamol and its metabolites except for the mercapturate-conjugate. The concentration of mercapturate change decreased with increasing TFA dose. TFA had no effect on the pentobarbital metabolites (P > 0.05). However, paracetamol (400 mg.kg-1) prolonged the sleeping time (by 110 min relative to the controls, P < 0.001). The TFA (P < 0.005) caused significant reduction in paracetamol-prolonged pentobarbital-induced sleep.

CONCLUSIONS

The mechanism of TFA's protective effect against the paracetamol-induced damage may be related to the inhibition of some metabolism progress of paracetamol and the reduction of the toxicity metabolite such as mercapturate-conjugate.

Renin-angiotensin system gene polymorphisms, blood pressure, dyslipidemia, and diabetes in Hong Kong Chinese: a significant association of tne ACE insertion/deletion polymorphism with type 2 diabetes

OBJECTIVE

In Chinese populations, hypertension is common and is a major risk factor for cerebrovascular and coronary heart disease, particularly when associated with diabetes. The clustering of these disorders and dyslipidemia and obesity is termed the metabolic syndrome and is increasing in prevalence in the populations of modernizing Asian nations. The renin-angiotensin system (RAS) helps maintain blood pressure and salt homeostasis and may play a role in the pathogenesis of aspects of the metabolic syndrome. We investigated three RAS gene polymorphisms--the ACE insertion/deletion (I/D), angiotensinogen (AGT) M235T, and angiotensin II type 1 receptor (AT1R) A1166C polymorphisms--for a possible role in modulating these disorders in 853 Chinese subjects with varying components of the metabolic syndrome.

RESEARCH DESIGN AND METHODS

The three gene polymorphisms of this cross-sectional study were detected using polymerase chain reaction-based protocols. The genotype frequencies were compared between the controls (n = 119) and both overlapping and nonoverlapping groups of patients with type 2 diabetes, hypertension, and dyslipidemia using chi2 test. Differences in levels of the biochemical parameters between the genotypes were determined using analysis of variance.

RESULTS

No significant relationship was identified between these polymorphisms and blood pressure in this population. Although the AT1RA1166C polymorphism was not associated with any aspect of the metabolic syndrome examined, there was limited evidence to suggest that the AGT M235T polymorphism may be associated with cholesterol levels. The ACE I allele was significantly more frequent in each group comprising subjects with type 2 diabetes/glucose intolerance (GIT), and the I allele was associated with higher fasting plasma glucose levels.

CONCLUSIONS

These findings suggest that these polymorphisms are unlikely to be involved in the pathogenesis of hypertension. The ACE I/D polymorphism was associated with the metabolic syndrome, having a higher frequency of I allele-containing genotypes in those groups, but this appeared to result predominantly from the relationship with type 2 diabetes/GIT in this population of Chinese subjects.

Urinary epinephrine and norepinephrine interrelations with obesity, insulin, and the metabolic syndrome in Hong Kong Chinese

The metabolic syndrome is characterized by a clustering of cardiovascular risk factors including type 2 diabetes mellitus, hypertension, dyslipidemia, and obesity. Elevated plasma insulin and urinary norepinephrine (noradrenaline) and reduced urinary epinephrine (adrenaline) excretion are associated with obesity in Caucasian populations. We examined the interrelationships between obesity, plasma insulin, and urinary catecholamine excretion in Chinese subjects with various components of the metabolic syndrome. A total of 577 Chinese subjects (aged 38 +/- 10 years; 68% with type 2 diabetes mellitus, hypertension, dyslipidemia, obesity, and/or albuminuria and 32% healthy subjects) were studied, all of whom had a plasma creatinine less than 150 micromol/L. The blood pressure, height, weight, waist and hip circumference, and fasting plasma glucose, insulin, lipid, and creatinine levels were measured. A 24-hour urine sample was collected for measurement of albumin and catecholamine excretion. The body mass index (BMI) and waist circumference were used as measures of general and central obesity, respectively. The insulin resistance index was estimated by the calculated product of fasting plasma insulin and glucose concentrations. Patients with an increasing number of components of the metabolic syndrome (type 2 diabetes mellitus, hypertension, dyslipidemia, obesity, and/or albuminuria) were more obese, hyperglycemic, dyslipidemic, and albuminuric and had higher blood pressure, plasma insulin, insulin resistance indices, and 24-hour urinary norepinephrine excretion but lower urinary epinephrine output (all P < .005). Increasing quintiles of BMI in the whole population or waist circumference in both sexes were associated with increasing trends for adverse lipid profiles, plasma insulin, insulin resistance indices, and urinary norepinephrine excretion but a decreasing trend for urinary epinephrine output (all P < .001). There were close associations between age, obesity, blood pressure, fasting plasma glucose, lipid, insulin, insulin resistance indices, and urinary catecholamine excretion. Using stepwise multiple regression analysis (all P < .001), 34% of the variability of the BMI and 45% of that of the waist circumference were independently related to gender (waist higher in males and BMI higher in females), increased plasma insulin, triglyceride, and urinary norepinephrine excretion, and decreased high-density lipoprotein (HDL) cholesterol and urinary epinephrine output. In Chinese subjects with different manifestations of the metabolic syndrome, hyperinsulinemia, insulin resistance, elevated norepinephrine, and reduced epinephrine excretion were closely associated with general and central obesity. Based on these findings, we postulate that complex interactions between the insulin and sympathoadrenal systems may lead to the development of obesity and the metabolic syndrome.

Albuminuria and the renin-angiotensin system gene polymorphisms in type-2-diabetic and in normoglycemic hypertensive Chinese

BACKGROUND

Albuminuria predicts nephropathy-related mortality in Caucasian and Chinese populations. The involvement of renin-angiotensin system (RAS) gene polymorphisms in the pathogenesis of nephropathy has been described predominantly in Caucasian populations. We have previously suggested that the angiotensinogen 235T variant may be associated with nephropathy in diabetic Chinese.

PATIENTS AND METHODS

To validate these findings and extend them to include non-diabetic nephropathy, we examined the association of albuminuria and gene polymorphisms of the angiotensinogen M235T, angiotensin-converting enzyme insertion/deletion and angiotensin II type I receptor A1166C polymorphisms in 614 Chinese subjects (66% type 2 diabetic, 16% normoglycemic hypertensives and 18% controls).

RESULTS

Obesity and higher blood pressure were associated with albuminuria in both diabetes and normoglycemic hypertension. In the diabetic group, albuminuria was also associated with increased insulin resistance and glycemic indices, duration of diabetes and adverse lipid profiles. Only the ACE gene polymorphism showed evidence of association with albuminuria, with the D allele being less frequent in the normoglycemic hypertensive patients with albuminuria (25.0%) than the controls (41.4%) or normoalbuminuric group (39.6%) and in those hypertensives at increased risk (albumin-to-creatinine ratio > 5.6 mg/mmol) of end-stage renal disease than those at lower risk (all p < 0.05), but not in the diabetic group. The D allele was also less prevalent in the total (31.9%) and normoalbuminuric (32.2%) diabetic groups than in the controls (p < 0.05).

CONCLUSION

In this cohort of Chinese subjects, the ACE gene polymorphism D allele was less frequent in normoglycemic hypertensive patients with albuminuria and in type 2 diabetes.

Obesity, independent of insulin resistance, is a major determinant of blood pressure in normoglycemic Hong Kong Chinese

Obesity and insulin resistance are considered important links underlying the development of hypertension. In Caucasians, there have been many reports of an association between insulin resistance and hypertension. However, this relationship is not consistently found in other ethnic groups. In this study, we examined the involvement of insulin resistance (assessed as fasting insulin-glucose product, FIGP) and general and central obesity as potential links in the development of hypertension in 413 normoglycemic Hong Kong Chinese (56.9% hypertensive) subjects. Anthropometric parameters (waist circumference [WC], waist-to-hip ratio [WHR], body mass index [BMI]), surrogate measures of insulin resistance (fasting plasma glucose, insulin, FIGP), fasting lipids and systolic (SBP) and diastolic (DBP) blood pressure were measured. Both male and female hypertensives were more obese and dyslipidemic, and the females had higher indices of insulin resistance than the normotensive subjects of the same gender. Before adjustment for age, gender, and adiposity, FIGP correlated with SBP in the total (r = .19, P = .009) and low BMI (r = .23, P < .05) and low WHR (r = .25, P < .01) groups. However, after adjustment, there was no significant relationship between FIGP and blood pressure. In contrast, BMI and WC were strongly associated with blood pressure (r > or = .41, P < .001 for both DBP and SBP in the total population), although in the group with general obesity, the strength of the relationship was weaker (r > or = .13). These relationships persisted after adjustment for age, gender, and FIGP. Obesity, therefore, appears to have a predominant role compared with insulin resistance in determining blood pressure in these normoglycemic Chinese.