G. Neil Thomas

Effects of Tai Chi and resistance training on cardiovascular risk factors in elderly Chinese subjects: a 12‐month longitudinal, randomized, controlled intervention study

Backgroundu2002 u2002Tai Chi is rapidly gaining in popularity, worldwide. This study was performed to assess its impact on cardiovascular risk factors in comparison with resistance training exercises in elderly Chinese subjects.

The role of angiotensin II Type 1 receptor antagonists in elderly patients with hypertension

Hypertension is a major risk factor for stroke and coronary events in elderly people and clinical trials have shown that treatment of hypertension with various drugs can result in a substantial reduction in cerebrovascular and cardiovascular events. The angiotensin II type 1 (AT1) receptor antagonists are the newest class of antihypertensive agents to be used widely in clinical practice. AT1 receptor antagonists can generally be given once-daily. They are also extremely well tolerated with minimal first-dose hypotension and an incidence of adverse effects similar to that seen with placebo. Adverse event rates are significantly lower than with other classes of antihypertensive drugs including ACE inhibitors. These factors result in improved compliance and increased rates of continuance on therapy. AT1 receptor antagonists show similar efficacy in lowering blood pressure to other classes of antihypertensive agents and their antihypertensive effect is potentiated when they are given concomitantly with low-dose thiazide diuretics. AT1 receptor antagonists are eliminated predominantly by the hepatic route but most are not subject to extensive metabolism and interactions with other drugs are uncommon. This is an advantage in the elderly, who are often receiving multiple medications which increases the risk for adverse drug interactions. Dose adjustments are not usually required in the elderly unless there is plasma volume depletion. Although plasma AT1 receptor antagonist concentrations are generally higher in the elderly than in younger subjects, this pharmacokinetic difference may be balanced by decreased activation of the circulating renin-angiotensin-aldosterone system in the elderly.Recent clinical studies in high-risk hypertensive patients with left ventricular hypertrophy or in patients with diabetic nephropathy or heart failure have demonstrated that AT1 receptor antagonists can improve clinical outcomes to a similar or sometimes greater extent than other antihypertensive agents. Many of these studies have included large numbers of older patients and have confirmed the excellent tolerability profile of these drugs. Thus, AT1 receptor antagonists should be considered as a possible first-line treatment or as a component of combination therapy in patients with type 2 diabetes mellitus and microalbuminuria or nephropathy and as an alternative or additional treatment to ACE inhibitors in patients with heart failure or left ventricular dysfunction. AT1 receptor antagonists also appear to reduce the onset of new diabetes compared with some other antihypertensive drugs. The benefits in terms of organ protection have mainly been seen in studies using higher doses of particular AT1 receptor antagonists and it is not certain at present whether these results can be extrapolated to other members of the class.As the elderly are more likely to have developed organ damage related to hypertension or to have heart failure or diabetes as concomitant conditions, AT1 receptor antagonists represent an appropriate option for many elderly patients. The main disadvantage of these drugs is the cost of the medication but this may be offset by their improved tolerability with fewer adverse reactions and thus increased compliance, resulting in better blood pressure control and fewer clinical events. Overall, AT1 receptor antagonists are well tolerated and efficacious for blood pressure-lowering when given as a single daily dose in elderly patients and have many potential benefits in high-risk hypertensive subjects.

Association of the metabolic syndrome with vascular disease in an older Chinese population : Guangzhou Biobank Cohort Study

Objective: To assess the prevalence of the metabolic syndrome (MS) and relative associations with vascular disease in an older Chinese population using the US National Cholesterol Education Program: Adult Treatment Panel (NCEP: ATP III) and International Diabetes Federation (IDF) definitions. Design: Cross-sectional study. Subjects: A total of 3035 men and 7291 women aged 50 to 85 yr recruited from Guangzhou, China. Measurements: All participants received a full medical check-up including measurement of blood pressure, obesity indices, fasting total, LDL-, HDL-cholesterol, triglycerides (TG) and glucose levels. Demographic information and self-reported history of physician-diagnosed coronary heart disease (CHD), stroke and myocardial infarction (MI) were collected through standardized interview. Results: The estimates under the two definitions differed substantially, with the age standardized prevalence of MS 15.57% using the NCEP: ATP III definition and 25.81% using the IDF definition. Among all participants, 80.23% were similarly classified using both definitions. The association between self-reported CHD, stroke and MI and the MS defined by the IDF definition was stronger than that by the NCEP: ATP III. Conclusions: The IDF compared to the ATP III definition shows a stronger association with the MS and associated vascular disease in Chinese. The prevalence of the MS is alarmingly high in this older Chinese population. Comprehensive strategies are needed for prevention and treatment of the MS to reduce the increased societal burden of cardiovascular disease in China.

Associations of apolipoprotein E exon 4 and lipoprotein lipase S447X polymorphisms with acute ischemic stroke and myocardial infarction

Abstract Background: Because apolipoprotein E (apoE) and lipopoprotein lipase (LPL) polymorphisms interact with each other and with other factors to affect lipid metabolism, we sought to determine their separate and combined effects in association with ischemic vascular disease. Methods: We performed a case-control study of 816 subjects: 246 acute ischemic stroke patients, 234 acute myocardial infarction patients, and 336 controls. APOE exon 4 and LPL S447X genotypes were determined. Results: APOE ɛ2 and ɛ4 homozygotes were increased in stroke (4.5% vs. 1.0%, p=0.008), while in myocardial infarction the ɛ4 allele was increased (12.6% vs. 9.5%, p=0.006) but ɛ2 was decreased (3.7% vs. 12.1%, p=0.000006). For subjects with either APOE ɛ2 or ɛ4 alleles, LPL X alleles were increased in vascular disease (OR=2.2, p=0.01). LPL X alleles displayed opposite tendencies toward association with disease when subjects were divided by sex, smoking, or APOE genotype. Meta-analysis and regression analysis of previous studies supported the sex and smoking dichotomies. Conclusion: This is the first report of an association of vascular disease with an interaction of APOE exon 4 and LPL S447X genotypes. Therefore, APOE genotypes and LPL S447X interactions with apoE, sex, and smoking may affect the risk of myocardial infarction and ischemic stroke.

Methylenetetrahydrofolate reductase gene A222V polymorphism and risk of ischemic stroke

Abstract The 5,10-methylenetetrahydrofolate reductase (MTHFR) gene 677C→T polymorphism causes an A222V amino acid change which affects MTHFR enzyme activity and can increase homocysteine, a vascular disease risk factor. This polymorphism was examined for association with stroke. In a case-control study of 241 ischemic stroke patients and 304 controls in Hong Kong, the V allele increased in stroke [28% vs. 20%, odds ratio (OR) 1.5, p=0.003]. A lack of significance for the increase in the VV genotype (7.5% vs. 4.6%, OR 1.7, p=0.16) may be due to its rarity in this region. V-allele carriers had more severe strokes (according to the NIH stroke scale). The association of the V allele with stroke occurred mostly in women or older subjects and was due to decreasing V allele frequency with age, as seen in other studies. This V frequency decline with age might be due to a loss of V-carrying controls from a higher risk of cancer, vascular disease, bone fracture, and kidney failure when folate is sparse. Examination of previous studies revealed that the association of VV genotype with stroke appeared stronger in Japan than elsewhere, possibly due to dietary differences. Perhaps folate supplementation for stroke prevention would particularly benefit VV individuals in such high-risk regions.

Smoking, smoking cessation and aortic arch calcification in older Chinese: the Guangzhou Biobank Cohort Study.

OBJECTIVEnTo study the association between smoking, smoking cessation and aortic arc calcification (AAC) in an older Chinese population.nnnMETHODSnA total of 3022 men and 7279 women aged 50-85 years were recruited and received a medical check-up including measurement of fasting plasma vascular risk factors. Two radiologists reviewed the posterior-anterior plain chest X-ray radiographs and assessed AAC together. Information on smoking status, socioeconomic and lifestyle factors was collected.nnnRESULTSnThe crude prevalence of AAC in men (38.58%) was lower than that in women (41.37%). The adjusted odds ratios of AAC increased significantly across never, ex- and current smokers in both genders. Dose-response relationships were observed among current smokers for smoking amount (cigarettes/day), smoking duration (years) and cigarette pack-years in both genders (all p<0.01). The odds ratios decreased significantly (p=0.018) with longer duration of quitting in light ex-smoking men (<23.5 pack-years) but showed no beneficial effect (p=0.72) for heavy ex-smokers (>or=23.5 pack-years).nnnCONCLUSIONnSmoking increased the risk of AAC in Chinese, while smoking cessation decreased the risk only in male light ex-smokers. Chest X-ray is a cheap and simple method to detect AAC, which should be an important warning signal for immediate smoking cessation.

Middle Cerebral Artery Stenosis Increased the Risk of Vascular Disease Mortality among Type 2 Diabetic Patients

Background: In Chinese populations, middle cerebral artery (MCA) stenosis is the most commonly identified intracranial vascular lesion, and has been shown to be associated with an increased risk of secondary stroke mortality, but has yet to be reported for primary events. We assess whether asymptomatic MCA stenosis is associated with mortality in Chinese type 2 diabetic patients. Methods: The presence of MCA stenosis was determined by transcranial Doppler and mortality data were collated in the Hong Kong Death Registry. Cox proportional hazards regression was used to determine if the MCA stenosis (n = 272, 53.7% 2-vessel disease) in 2,197 diabetics was associated with all-cause or vascular disease mortality, including after adjustment for conventional vascular risk factors. Anthropometric and fasting biochemical parameters were compared between diabetic patients with MCA stenosis and without evidence of stenosis. Results: A total of 191 deaths were identified (30.9% of vascular disease origin) during a follow-up of 18,279 patient years over 8.32 years. After adjustment for age, gender and diabetes duration, the hazard ratios for vascular mortality for 1- and 2-vessel disease were 2.47 (95% CI = 1.13–5.38) and 4.47 (95% CI = 2.24–8.82), p < 0.001 for trend, for increasing vascular mortality with increasing severity of cerebrovascular involvement, but 0.81 (95% CI = 0.45–1.47) and 2.23 (95% CI = 1.45–1.47), p = 0.001 for trend, for all-cause mortality. For vascular mortality, further adjustments for anthropometric and fasting biochemical parameters, or existing disease and treatment history increased the hazard ratios for 1-vessel disease slightly but attenuated the risk for 2-vessel disease evidently, 2.81 (95% CI = 1.10–7.16) and 2.85 (95% = CI 1.11–7.33), p = 0.026. Conclusion: The presence of MCA stenoses was an independent predictor of vascular mortality in these diabetics. More aggressive treatment of risk factors in these subjects merits further evaluation.

Growth environment and sex differences in lipids, body shape and diabetes risk.

Background Sex differences in lipids and body shape, but not diabetes, increase at puberty. Hong Kong Chinese are mainly first or second generation migrants from China, who have shared an economically developed environment for years, but grew up in very different environments in Hong Kong or contemporaneously undeveloped Guangdong, China. We assessed if environment during growth had sex-specific associations with lipids and body shape, but not diabetes. Methodology and Principal Findings We used multivariable regression in a population-based cross-sectional study, undertaken from 1994 to 1996, of 2537 Hong Kong Chinese residents aged 25 to 74 years with clinical measurements of ischaemic heart disease (IHD) risk, including HDL-cholesterol, ApoB, diabetes and obesity. Waist-hip ratio was higher (mean difference 0.01, 95% CI 0.001 to 0.02) in men, who had grown up in an economically developed rather than undeveloped environment, as was apolipoprotein B (0.05 g/L, 95% CI 0.001 to 0.10), adjusted for age, socio-economic status and lifestyle. In contrast, the same comparison was associated in women with lower waist-hip ratio (−0.01, 95% CI −0.001 to −0.02) and higher HDL-cholesterol (0.05 mmol/L, 95% CI 0.0004 to 0.10). The associations in men and women were significantly different (p-values<0.001). There were no such differences for diabetes. Conclusions Growth in a developed environment with improved nutrition may promote higher sex-steroids at puberty producing an atherogenic lipid profile and male fat pattern in men but the opposite in women, with tracking of increased male IHD risk into adult life.

Obesity, high-sensitive C-reactive protein and snoring in older Chinese: The Guangzhou Biobank Cohort Study

BACKGROUNDnabitual snoring and elevated high-sensitive C-reactive protein (HsCRP) have both been associated with increased risk of cardiovascular disease. However, snoring and HsCRP are elevated in obese states which may thus be the primary determinant of both. We therefore investigated whether snoring may mediate the increased vascular risk directly through increased inflammation as indicated by HsCRP levels or if other determinants predominated in a large older Chinese population.nnnMETHODSnA total of 2508 males and 5709 females aged 50-85 years received a medical check-up including measurement of blood pressure, obesity indices, fasting total, LDL-, HDL-cholesterol, triglycerides, glucose and HsCRP. Information on self-reported snoring status was collected by standardized interview.nnnRESULTSnThe age-adjusted geometric mean HsCRP concentrations increased significantly with higher snoring frequency in both genders (linear trend, p=0.02 for men and p<0.001 for women), but the association was no longer significant after controlling for waist and BMI. Furthermore, HsCRP levels were not significantly associated with snoring frequency groups stratified by BMI/waist quintiles in both genders, except for the 4th waist quintile in men. No interaction was observed between snoring and BMI/waist on HsCRP levels. The multivariate analysis showed that, in both genders, obesity, but not HsCRP, was associated with snoring.nnnCONCLUSIONSnOur results showed that snoring frequency did not have an independent effect on inflammation after adjusting for adiposity, and may thus contribute to vascular disease through alternative mechanisms.

Age-related anthropometric remodelling resulting in increased and redistributed adiposity is associated with increases in the prevalence of cardiovascular risk factors in Chinese subjects.

Ageing promotes increases in the prevalence of components of the metabolic syndrome, which obesity often underlies.