Biomedical subjects

Neil Chapman

Publications and source records attributed to Neil Chapman.

8 recordsLinked to original sources

PubMed2003

The ACE gene I/D polymorphism is not associated with the blood pressure and cardiovascular benefits of ACE inhibition.

The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene might have consequences for the risks of vascular diseases. We examined the ACE genotype and the effects of a perindopril-based blood pressure-lowering regimen on macrovascular events, dementia, and cognitive decline among hypertensive and nonhypertensive patients with a history of cerebrovascular disease. ACE I/D genotypes were measured in 5688 of 6105 individuals with previous stroke or transient ischemic attack who participated in the PROGRESS trial. The DD genotype was significantly (P<0.0001) less frequent in Asian subjects (Chinese and Japanese, 14.7%) than in non-Asian subjects (32.0%). Controlling for racial background, there were no associations between ACE genotypes and cerebrovascular disease history or cardiovascular risk factors, including baseline blood pressure. The ACE genotype was not associated with the long-term risks of stroke, cardiac events, mortality, dementia, or cognitive decline; neither did the ACE genotype predict the blood pressure reduction associated with the use of the ACE inhibitor perindopril. Similarly, there was no evidence that the ACE genotype modified the relative benefits of ACE inhibitor-based therapy over placebo. This study provides no evidence that in patients with cerebrovascular disease, knowledge of ACE genotype is useful for predicting either the risk of disease or the benefits of perindopril-based blood pressure-lowering treatment.

Adult↗

PubMed2003

Effects of blood pressure lowering with perindopril and indapamide therapy on dementia and cognitive decline in patients with cerebrovascular disease.

BACKGROUND: High blood pressure and stroke are associated with increased risks of dementia and cognitive impairment. This study aimed to determine whether blood pressure lowering would reduce the risks of dementia and cognitive decline among individuals with cerebrovascular disease. METHODS: The Perindopril Protection Against Recurrent Stroke Study (PROGRESS) was a randomized, double-blind, placebo-controlled trial conducted among 6105 people with prior stroke or transient ischemic attack. Participants were assigned to either active treatment (perindopril for all participants and indapamide for those with neither an indication for nor a contraindication to a diuretic) or matching placebo(s). The primary outcomes for these analyses were dementia (using DSM-IV criteria) and cognitive decline (a decline of 3 or more points in the Mini-Mental State Examination score). RESULTS: During a mean follow-up of 3.9 years, dementia was documented in 193 (6.3%) of the 3051 randomized participants in the actively treated group and 217 (7.1%) of the 3054 randomized participants in the placebo group (relative risk reduction, 12% [95% confidence interval, -8% to 28%]; P =.2). Cognitive decline occurred in 9.1% of the actively treated group and 11.0% of the placebo group (risk reduction, 19% [95% confidence interval, 4% to 32%]; P =.01). The risks of the composite outcomes of dementia with recurrent stroke and of cognitive decline with recurrent stroke were reduced by 34% (95% confidence interval, 3% to 55%) (P =.03) and 45% (95% confidence interval, 21% to 61%) (P<.001), respectively, with no clear effect on either dementia or cognitive decline in the absence of recurrent stroke. CONCLUSIONS: Active treatment was associated with reduced risks of dementia and cognitive decline associated with recurrent stroke. These findings further support the recommendation that blood pressure lowering with perindopril and indapamide therapy be considered for all patients with cerebrovascular disease.

Aged↗

PubMed2003

Twelve-year changes in vascular risk factors and their associations with mortality in a cohort of 3499 Thais: the Electricity Generating Authority of Thailand Study.

BACKGROUND: Vascular mortality is increasing in economically developing countries such as Thailand but reliable data about the determinants of these changes are few. METHODS: In 1985, male and female employees of the Electricity Generating Authority of Thailand took part in a cardiovascular risk factor survey. In 1997, a follow-up survey was conducted and causes of death were determined for those subjects known to have died. Changes in levels of vascular risk factors over 12 years, and the associations of baseline risk factors with vascular mortality, were calculated. RESULTS: The 1985 survey recruited 3499 volunteers (average age 43 years) of whom 23% were female. In 1997, vital status was determined for 3318 (95%) and 2967 (85%) of the study participants were resurveyed. Mean levels of systolic blood pressure (SBP) and diastolic blood pressure (DBP), body mass index, total cholesterol and high density lipoprotein (HDL) cholesterol all increased over the 12-year follow-up period. Over the same time, the prevalence of diabetes also rose but the proportion of current smokers decreased. Vascular diseases were the most frequent cause of death during follow-up (n = 46), were positively associated with baseline age, SBP, DBP, smoking, diabetes, male sex, and total cholesterol, and were negatively associated with HDL cholesterol. CONCLUSIONS: Levels of most vascular risk factors worsened over the 12-year period between 1985 and 1997. The associations between baseline risk factor levels and vascular mortality were consistent with those observed in other populations. Interventions that control vascular risk factors have the potential to avert much premature vascular disease in Thailand.

Adult↗

PubMed2003

International Society of Hypertension (ISH): statement on blood pressure lowering and stroke prevention.

The ISH Statement on blood pressure lowering and stroke prevention was finalized after presentation and discussion at the World Health Organization and International Society of Hypertension (WHO-ISH) Meeting on Stroke and Blood Pressure, held in Melbourne Australia, 5-7 December 2002. The meeting was conducted under the auspice of the Austin Hospital Medical Research Foundation, Melbourne.

Anticoagulants↗

PubMed2002

Midwall myocardial shortening in athletic left ventricular hypertrophy.

BACKGROUND: Patients with pathological left ventricular hypertrophy have depressed midwall systolic shortening in spite of normal indices of left ventricular chamber function and a reduced midwall function has been observed to be an independent predictor of cardiovascular risk. Whether midwall shortening is depressed in physiological hypertrophy is unknown. METHODS: Forty-two subjects, 27 athletes and 15 age- and sex-matched normal control subjects (group 1) were studied. The athletes were divided into those with eccentric hypertrophy (group 2) and those with concentric hypertrophy (group 3). Systolic left ventricular function was assessed at the midwall and endocardium using two-dimensional echocardiography in all subjects. RESULTS: Left ventricular mass index was significantly greater in both athletic groups than in controls (group 1, 101+/-5.8 g/m(2), group 2, 141+/-11.1*, group 3, 155+/-5.8*; *P<0.01 compared with group 1). Left ventricular systolic function assessed at the endocardium was similar among all three groups (ejection fraction: group 1, 66.2+/-2.38, group 2, 66.8+/-1.44, group 3, 63.7+/-1.66%; endocardial fractional shortening: group 1, 37.1+/-1.71, group 2, 37.6+/-1.13, group 3, 35.1+/-1.25%). However, fractional shortening at the midwall was reduced in the concentric hypertrophy athletes compared with the other two groups (midwall fractional shortening: group 1, 21.9+/-1.1, group 2, 21.9+/-0.86, group 3, 18.4+/-0.96*%; P<0.05 compared with groups 1 and 2). CONCLUSION: Subjects with physiological concentric hypertrophy have depressed midwall fractional shortening. This suggests that the observed discrepancy between midwall and endocardial shortening in patients with left ventricular hypertrophy is likely to be a function of the geometry and not necessarily a reflection of pathology within the myocardium.

Adult↗

PubMed2002

Ethnic differences in carotid and left ventricular hypertrophy.

OBJECTIVES: Afro-Caribbean subjects have a higher prevalence of hypertension, a lower prevalence of ischaemic heart disease and a higher premature mortality compared to White Europeans. Left ventricular hypertrophy (LVH) is also more prevalent in Afro-Caribbeans even at similar levels of blood pressure. It is widely believed that carotid artery intima-media thickening (IMT) represents an early marker for the development of atheroma, and carotid IMT and LVH are associated in White populations. Whether the relationship between carotid IMT and LVH is similar in Black subjects is unknown. METHODS: Thirty-eight subjects were studied using carotid and femoral ultrasonography and echocardiography; 19 Afro-Caribbean and 19 White European subjects were matched for age, sex and mean 24 h systolic blood pressure. RESULTS: The Afro-Caribbean group had a significantly greater left ventricular mass index (LVMI) compared to the White European: 136.4 +/- 6.1 versus 112.4 +/- 6.2 g/m2, P < 0.01. However, carotid IMT, carotid diameter, femoral IMT and femoral diameter were similar between the groups: 0.75 +/- 0.02 versus 0.77 +/- 0.04 mm, 6.54 +/- 0.15 versus 6.56 +/- 0.16 mm, 0.66 +/- 0.03 versus 0.68 +/- 0.03 mm and 8.40 +/- 0.33 versus 8.25 +/- 0.23 mm, respectively. CONCLUSIONS: Afro-Caribbean subjects with similar blood pressures have similar mean carotid and femoral IMTs compared to White Europeans, in spite of marked differences in LVMI. Whether this reflects a discrepancy in the degree of cardiovascular risk for similar levels of LVMI or whether this is a reflection of an altered pattern of target organ damage associated with hypertension in Afro-Caribbean subjects is unclear.

Adult↗

PubMed2002

Retinal vascular tree morphology: a semi-automatic quantification.

A semi-automatic method to measure and quantify geometrical and topological properties of continuous vascular trees in clinical fundus images is described. Measurements are made from binary images obtained with a previously described segmentation process. The skeletons of the segmented trees are produced by thinning,ff branch and crossing points are identified and segments of the trees are labeled and stored as a chain code. The operator selects a tree to be measured and decides if it is an arterial or venous tree. An automatic process then measures the lengths, areas and angles of the individual segments of the tree. Geometrical data and the connectivity information between branches from continuous retinal vessel trees are tabulated. A number of geometrical properties and topological indexes are derived. Vessel diameters and branching angles are validated against manual measurements and several derived geometrical and topological properties are extracted from red-free fundus images of ten normotensive and ten age- and sex-matched hypertensive subjects and compared with previously reported results.

Adult↗

PubMed2002

Is carotid artery intima-media thickening a reliable marker of early atherosclerosis?

BACKGROUND: It is widely believed that carotid artery intima-media thickening represents an early marker for the development of atheroma. However, carotid intima-media thickening might also be expected to occur in response to an increased tensile stress and decreased wall shear stress which may accompany physical exercise. DESIGN, METHODS, AND RESULTS: In order to test this hypothesis 24 athletes (professional footballers) were compared to 14 age and sex matched control subjects. Each subject underwent carotid and femoral ultrasonography and echocardiography. The athletes had a greater left ventricular mass index compared with the controls: 135 (127-143) vs. 104 (91-116) g/m2, p < 0.001. In addition, they had a greater carotid intima-media thickness (IMT): 0.55 (0.52-0.57) vs. 0.51 (0.48-0.54) mm, p < 0.05. However, carotid artery diameters, femoral IMT and femoral artery diameters were similar: 6.0 (5.9-6.2) vs. 5.8 (5.6-6.1) mm, 0.43 (0.42-0.45) vs. 0.43 (0.41-0.45) mm and 8.3 (8.0-8.6) vs. 8.4 (8.0-8.7) mm, respectively. CONCLUSIONS: The increased carotid IMT of the athletes may result from intermittent exposure to markedly elevated systemic arterial pressures during exercise, resulting in intermittent elevations in carotid wall tensile stress. The lack of a disparity between athletes and controls for femoral IMT may be explained by the intermittent elevation of femoral wall tensile stress being accompanied by increased femoral artery blood flow and wall shear stress, which would tend to reduce any wall thickening. This is an important observation, since it suggests that an increased carotid IMT cannot be relied on solely as a marker of early atherosclerosis.

Adolescent↗