Showing papers by "David E. Newby published in 2004"
TL;DR: The current evidence regarding fish oils and cardiovascular disease, their possible mechanism of action, and potential future developments and research strategies are reviewed.
Abstract: Omega 3 fatty acids from fish and fish oils can protect against coronary heart disease. Both health professionals and the public are increasingly interested in their role in the prevention and management of coronary heart disease. In this era of multiple pharmacological treatments for cardiovascular disease many believe that simple dietary interventions or nutritional supplements may be a more natural and acceptable method of providing benefits. Several areas of uncertainty remain. The optimal intake of omega 3 fatty acids is not firmly established, nor is their mechanism of action fully understood. Some studies have produced conflicting results, and concerns have been increasing about environmental contamination of certain fish. This article reviews the current evidence regarding fish oils and cardiovascular disease, their possible mechanism of action, and potential future developments and research strategies.
435 citations
TL;DR: Type 1 diabetes is associated with increased CD40L expression and platelet-monocyte aggregation, which may contribute to the proinflammatory and prothrombotic state as well as the accelerated atherogenesis associated with this disorder.
107 citations
TL;DR: Findings are consistent with the suggestion that central aortic stiffness may promote the development of coronary atherosclerosis and ischaemic heart disease and may be a useful non-invasive surrogate marker for the extent of coronary Atherosclerosis.
Abstract: ObjectiveArterial stiffness is an emerging major risk factor for cardiovascular morbidity and mortality. The aim of the present study was to assess if coronary artery plaque load correlates with non-invasive measures of arterial stiffness. DesignProspective investigational study.SettingTertiary univ
88 citations
TL;DR: The natural history of calcific aortic stenosis is discussed, recent insights into its pathogenesis are highlighted, and the potential role of novel therapeutic interventional strategies is discussed.
Abstract: Calcific aortic stenosis is the commonest adult valvular heart condition seen in the western world. Its prevalence is continuing to rise, with predominance in older patients who are frequently undergoing successful aortic valve replacement. This review discusses the natural history of calcific aortic stenosis, highlights recent insights into its pathogenesis, and outlines current medical and surgical management. The potential role of novel therapeutic interventional strategies is discussed.
66 citations
TL;DR: The present study does not support the use of thoracic bioimpedance in its current form as an alternative to thermodilution in stable patients with chronic heart failure.
Abstract: Objectives The measurement of cardiac output by thoracic bioimpedance has been previously assessed in several studies. However, there continues to be disagreement as to whether this technique is sufficiently accurate for use in clinical practice or research. The current study aimed to compare thoracic bioimpedance (CO T B ) with thermodilution (CO T D ) in patients with stable chronic heart failure. Methods and results A total of 282 paired measurements of cardiac output from 11 patients were analysed. There was good correlation between CO T B and CO T D (r=0.76, P<0.0001). However, Bland-Altman analysis revealed an average difference between values of 0.3 (2.2) l/min (P= 0.02), suggesting a small average bias but marked variability in results. There was no significant correlation when results were expressed as percentage change from baseline and a significant average difference between values of 10.1 (30.1 )%. There was no difference in between-day repeatability between thermodilution and thoracic bioimpedance [-0.2(1.2) versus 0.1 (1.0) l/min, P=0.7]. Conclusions This study demonstrates a correlation between the techniques but shows a poor level of agreement. The method of CO T B underestimated cardiac output compared with CO T D , and this difference appeared greater with higher cardiac outputs. Agreement was worse when results were expressed as change from baseline. The present study does not support the use of thoracic bioimpedance in its current form as an alternative to thermodilution in stable patients with chronic heart failure.
39 citations
TL;DR: Neither acute local intra-arterial nor prolonged oral vitamin C supplementation reverses smoking-related endothelial dysfunction and impaired endogenous t-PA release, which concludes that the adverse vascular actions of smoking are not principally mediated through oxidative stress.
Abstract: :Blood flow and plasma fibrinolytic factors were measured on five occasions in both forearms of eight otherwise healthy male smokers during unilateral brachial artery infusion of the endothelium-dependent vasodilator, substance P (2 to 8 pmol/min), and the endothelium-independent vasodilator
24 citations
TL;DR: The effects of big ET-1([1-38]) and phosphoramidon suggest the presence of endogenous ECE activity in the skin.
Abstract: Aims Endothelin-1 (ET-1[1−21]) is an extremely potent vasoconstrictor in the human skin microcirculation and is generated from larger precursor peptides. The aims of the present study were to assess the vasoactive effects of these precursors as well as endothelin blockade in the human skin microcirculation, in vivo.
Methods Six healthy volunteers received intradermal injections of a range of doses of big ET-1[1−38], ET-1[1−31], ET-1[1−21], BQ-123 (ETA receptor antagonist), BQ-788 (ETB receptor antagonist), phosphoramidon [endothelin converting enzyme (ECE) inhibitor] or saline control (0.9%). Skin blood flow (SBF) was measured using standard laser Doppler flowmetry.
Results Big ET-1[1−38], ET-1[1−31] and ET-1[1−21] reduced SBF when compared with saline control (P < 0.01 for all). Big ET-1[1−38] and ET-1[1−31] were less potent than ET-1[1−21] as defined by skin vasoconstriction. Phosphoramidon, BQ-123 and BQ-788, given alone, all caused vasodilatation in the human skin microcirculation (P < 0.01 for all).
Conclusions In the human skin microcirculation, big ET-1[1−38] and ET-1[1−31] are less potent vasoconstrictors than ET-1[1−21]. The effects of big ET-1[1−38] and phosphoramidon suggest the presence of endogenous ECE activity in the skin. In contrast to skeletal muscle resistance vessels, ET-1[1−21] contributes to the maintenance of skin microvascular tone through both ETA and ETB receptor-mediated vasoconstriction.
22 citations
TL;DR: It is concluded that contrast significantly increases Doppler velocities and produces modest improvements in reproducibility of LVOT diameter and AVA, and is suggested that, when assessing patients with aortic stenosis, contrast agents should be considered in patients who are difficult to image with poor baseline LVOT images or Dopplers studies, or where there is poor interobserver reproduCibility.
Abstract: Observer variability may limit assessment of aortic stenosis by Doppler echocardiography. This study aimed to assess whether echocardiographic contrast agent improves reproducibility of aortic valve area (AVA) measurements for patients with aortic stenosis. In all, 20 patients with aortic stenosis (67 ± 10 years old) underwent noncontrast and contrast Doppler echocardiography on 2 occasions, 3 weeks apart. Intraobserver and interobserver coefficients of reproducibility were 0.36 and 0.20 cm for left ventricular outflow tract (LVOT) diameter, and 0.38 and 0.24 cm 2 for AVA, respectively. Although intraobserver reproducibility was unaffected, contrast improved interobserver reproducibility for LVOT diameter (mean of differences −0.02 ± 0.07 cm vs 0.01 ± 0.10 cm, P 2 vs 0.07 ± 0.12 cm 2 , P P P
15 citations
TL;DR: The data suggest that remodelled segments are predominantly composed of fibrous plaque, as identified by RF analysis, although plaque composition is similar, irrespective of the remodelling type.
Abstract: We aimed to characterise and to identify the predominant plaque type in vivo using unprocessed radiofrequency (RF) intravascular ultrasound (US) backscatter, in remodelled segments of human atherosclerotic coronary arteries. A total of 16 remodelled segments were identified using a 30-MHz intravascular ultrasound (IVUS) scanner in vivo . Of these, 9 segments were classified as positively remodelled (> 1.05 of the total vessel area in comparison with the proximal and distal reference segments) and 7 as negatively remodelled ( 2 vs. 8.7 ± 0.9 mm 2 , p 2 vs. 4.4 ± 0.8 mm 2 , p = 0.05) than negatively remodelled segments. Both positively and negatively remodelled segments had a greater percentage of fibrous plaque ( p in vivo in human atherosclerotic coronary arteries. Our data suggest that remodelled segments are predominantly composed of fibrous plaque, as identified by RF analysis, although plaque composition is similar, irrespective of the remodelling type. (E-mail: a.mcleod@ed.ac.uk)
9 citations
TL;DR: It is demonstrated that patients with chronic heart failure have normal plasma endothelin-1[1-31] concentrations, which suggests that, in contrast to big endothelins-1 [1-38], plasma endothermolysis 1-31 is unlikely to be a useful prognostic marker in patients with Chronic heart failure.
Abstract: Endothelin-1[1-31] is a recently discovered member of the endothelin family with vasoactive properties in several animal models and in man in vivo. It is generated from big endothelin-1 by human mast cell chymase and may be a novel intermediary peptide in the production of endothelin-1[1-21]. Given that both big endothelin-1[1-38] and chymase activity are increased in chronic heart failure, the aim of this study was to determine whether plasma endothelin-1[1-31] concentrations are elevated in patients with chronic heart failure. Plasma endothelin-1[1-31] concentrations were measured by enzyme-linked immunosorbent assay in nine patients with chronic heart failure, and nine age- and sex-matched control subjects. Consistent with previous studies, plasma concentrations of big endothelin-1[1-38] were elevated in patients compared with controls (17.1 +/- 4.4 pg/mL vs 8.9 +/- 3.4 pg/mL, P = 0.002), although there were no differences in plasma endothelin-1[1-21] (3.3 +/- 0.4 pg/mL vs 3.4 +/- 0.7 pg/mL, P = 0.7) or endothelin-1[1-31] (both 1.1 +/- 0.1 pg/mL, P = 0.2) concentrations. We have demonstrated that patients with chronic heart failure have normal plasma endothelin-1[1-31] concentrations. This suggests that, in contrast to big endothelin-1[1-38], plasma endothelin-1[1-31] is unlikely to be a useful prognostic marker in patients with chronic heart failure.
4 citations
TL;DR: The marine derived omega 3 fatty acids are focused on because of the larger and clearer evidence base and the need for further trials of α linolenic acid in coronary heart disease.
Abstract: Editor—Farmed fish such as salmon and trout generally have as much if not more omega 3 fatty acids per gram than wild fish.1 However, because farmed fish contain more total fat than wild fish, they have a smaller proportion of omega 3 when calculated as a percentage of total fat. We think that the absolute amount of omega 3 per gram of fish is the more relevant figure.
Supplementation of animal feed with fish oils will not address concerns about the depletion of fish stocks since this will clearly entail the harvesting of even more fish. However, we wanted to highlight that this is a potential approach to increase the dietary consumption of omega 3 oils in people unwilling or unable to eat fish. We acknowledge that the juxtaposition of these two independent points in the text box is rather misleading.
We intentionally focused our article on the marine derived omega 3 fatty acids because of the larger and clearer evidence base. We cannot assume that α linolenic acid confers the same benefits as it is a structurally distinct short chain polyunsaturated fatty acid with only limited conversion in humans to the longer chain eicosapentanoic acid and docosahexanoic acid.2
Whereas α linolenic acid may confer cardiac protection as part of a Mediterranean diet,3 the direct benefits of α linolenic acid have not been firmly established. We agree that ongoing concerns about fish stocks highlight the need for further trials of α linolenic acid in coronary heart disease.
TL;DR: Stable angina produces symptoms of exertional chest pain due to fixed atherosclerotic narrowing of the coronary artery, and requires chronic therapy, while the acute coronary syndromes, namely acute myocardial infarction and unstable angina, occur as a result of plaque rupture or erosion leading to acute coronary arterial thrombosis and occlusion.
Abstract: Coronary atherosclerosis is a nearly universal finding in people over 75 years old living in developed countries, but is often sub-clinical. Broadly speaking, symptomatic patients manifest coronary artery disease in two distinct ways: chronic stable angina or an acute coronary syndrome. Stable angina produces symptoms of exertional chest pain due to fixed atherosclerotic narrowing of the coronary artery, and requires chronic therapy. In contrast, the acute coronary syndromes, namely acute myocardial infarction (MI) and unstable angina, occur as a result of plaque rupture or erosion leading to acute coronary arterial thrombosis and occlusion that requires emergency hospitalization and treatment.