Heteroplasmic mitochondrial DNA variants in cardiovascular diseases.

Mitochondria are implicated in the pathogenesis of cardiovascular diseases (CVDs) but the reasons for this are not well understood. Maternally-inherited population variants of mitochondrial DNA (mtDNA) which affect all mtDNA molecules (homoplasmic) are associated with cardiometabolic traits and the risk of developing cardiovascular disease. However, it is not known whether mtDNA mutations only affecting a proportion of mtDNA molecules (heteroplasmic) also play a role. To address this question, we performed a high-depth (~1000-fold) mtDNA sequencing of blood DNA in 1,399 individuals with hypertension (HTN), 1,946 with ischemic heart disease (IHD), 2,146 with ischemic stroke (IS), and 723 healthy controls. We show that the per individual burden of heteroplasmic single nucleotide variants (mtSNVs) increases with age. The age-effect was stronger for low-level heteroplasmies (heteroplasmic fraction, HF, 5-10%), likely reflecting acquired somatic events based on trinucleotide mutational signatures. After correcting for age and other confounders, intermediate heteroplasmies (HF 10-95%) were more common in hypertension, particularly involving non-synonymous variants altering the amino acid sequence of essential respiratory chain proteins. These findings raise the possibility that heteroplasmic mtSNVs play a role in the pathophysiology of hypertension.

The Combination of Beta-Blockers and ACE Inhibitors Across the Spectrum of Cardiovascular Diseases.

Cardiovascular disease is the leading cause of mortality worldwide, affecting a wide range of patients at different stages across the cardiovascular continuum. Hypertension is one of the earliest risk factors in this continuum and can be controlled in most patients with currently available antihypertensive agents. However, goals are often not met because treatments are not optimized in terms of tailoring therapy to individual patients based on their hypertension subclass and cardiovascular risk profile and initiating early use of adapted-dose, single-pill combinations. In this context, beta-blockers in combination with angiotensin-converting enzyme (ACE) inhibitors are of special interest as a result of their complementary actions on the sympathetic nervous system and renin-angiotensin-aldosterone system, two interlinked pathways that influence cardiovascular risk and disease outcomes. In addition to their antihypertensive actions, beta-blockers are used to manage arrhythmias and treat angina pectoris and heart failure, while ACE inhibitors provide cardioprotection in patients with acute coronary syndromes and treat congestive heart failure. A broad range of patients may therefore receive the combination in routine clinical practice. This paper examines the supporting evidence for beta-blockers and ACE inhibitors in each of the above indications and considers the rationale for combining these agents into a single pill, using data from bisoprolol and perindopril randomized controlled trials as supporting evidence. Combining these established antihypertensive agents into a single pill continues to provide effective blood pressure lowering and improved cardiovascular outcomes while allowing a greater proportion of patients to rapidly achieve treatment targets.

The my experience of taking medicines (MYMEDS) questionnaire for assessing medicines adherence barriers in post-myocardial infarction patients: development and utility.

BACKGROUND: The 'My Experience of Taking Medicines' (MYMEDS) questionnaire is a self-reporting tool for identifying modifiable adherence barriers among individuals prescribed post-myocardial infarction (MI) secondary prevention medicines (SPM) in clinical practice. It was found to be a useful tool to support the conduction of patient-centred consultation in cardiology outpatient leading to improved outcomes including better adherence to SPM and patient satisfaction. This study describes the rationale and development of the MYMEDS tool, its performance and usefulness in identifying modifiable barriers to adherence in cardiology medical practice including user feedback of 204 consecutive post-MI patients who completed an evaluation based on MYMEDS. METHODS: Modifiable non-adherence factors were initially identified based on literature review and stakeholder feedback. A draft MYMEDS questionnaire was piloted in 10 patients and adapted accordingly. The final version comprises six sections, covering current medicines, understanding and satisfaction with medicines, concerns about medicines, practical adherence barriers, fitting medicines into daily routine, and adherence to individual SPMs. The questionnaire was mailed to post-MI patients who then attended an outpatient medicines optimisation clinic. RESULTS: Mean age was 70.5 years and 67.6% were male. The tool was effective in revealing modifiable adherence barriers that could be addressed during the consultation. There were high rates of concern that SPMs could be harmful (33.2%) or overprescribed (43.2%), practical issues with swallowing medicines (8.2%), opening packaging (7.3%) or accessing repeat prescriptions (5.2%), forgetfulness (19.7%), and concerns about inconvenience (13.5%). Mean number of barriers per patient was 1.8 ± 1.5. The medications most commonly associated with non-adherence were statins (21.5%), angiotensin II receptor blockers (21.1%), and antiplatelet agents (18.5%). In total, 42.5% of patients acknowledged non-adherence behaviour. Patient feedback on MYMEDS was positive, with near-unanimous agreement that it was simple, clear and not too long, and that it enabled them to raise any concerns they had about their medicines. Patients reported that their individual medicines related needs were better addressed. CONCLUSIONS: MYMEDS is a practical tool that can successfully identify modifiable barriers to SPM adherence which can be addressed in a clinical setting. It can be easily rolled out in daily clinical practice to enable individualised person-centred medicines optimisation consultation.

Variant ASGR1 Associated with a Reduced Risk of Coronary Artery Disease.

BACKGROUND: Several sequence variants are known to have effects on serum levels of non-high-density lipoprotein (HDL) cholesterol that alter the risk of coronary artery disease. METHODS: We sequenced the genomes of 2636 Icelanders and found variants that we then imputed into the genomes of approximately 398,000 Icelanders. We tested for association between these imputed variants and non-HDL cholesterol levels in 119,146 samples. We then performed replication testing in two populations of European descent. We assessed the effects of an implicated loss-of-function variant on the risk of coronary artery disease in 42,524 case patients and 249,414 controls from five European ancestry populations. An augmented set of genomes was screened for additional loss-of-function variants in a target gene. We evaluated the effect of an implicated variant on protein stability. RESULTS: We found a rare noncoding 12-base-pair (bp) deletion (del12) in intron 4 of ASGR1, which encodes a subunit of the asialoglycoprotein receptor, a lectin that plays a role in the homeostasis of circulating glycoproteins. The del12 mutation activates a cryptic splice site, leading to a frameshift mutation and a premature stop codon that renders a truncated protein prone to degradation. Heterozygous carriers of the mutation (1 in 120 persons in our study population) had a lower level of non-HDL cholesterol than noncarriers, a difference of 15.3 mg per deciliter (0.40 mmol per liter) (P=1.0×10(-16)), and a lower risk of coronary artery disease (by 34%; 95% confidence interval, 21 to 45; P=4.0×10(-6)). In a larger set of sequenced samples from Icelanders, we found another loss-of-function ASGR1 variant (p.W158X, carried by 1 in 1850 persons) that was also associated with lower levels of non-HDL cholesterol (P=1.8×10(-3)). CONCLUSIONS: ASGR1 haploinsufficiency was associated with reduced levels of non-HDL cholesterol and a reduced risk of coronary artery disease. (Funded by the National Institutes of Health and others.).

Protein-Truncating Variants at the Cholesteryl Ester Transfer Protein Gene and Risk for Coronary Heart Disease.

RATIONALE: Therapies that inhibit CETP (cholesteryl ester transfer protein) have failed to demonstrate a reduction in risk for coronary heart disease (CHD). Human DNA sequence variants that truncate the CETP gene may provide insight into the efficacy of CETP inhibition. OBJECTIVE: To test whether protein-truncating variants (PTVs) at the CETP gene were associated with plasma lipid levels and CHD. METHODS AND RESULTS: We sequenced the exons of the CETP gene in 58 469 participants from 12 case-control studies (18 817 CHD cases, 39 652 CHD-free controls). We defined PTV as those that lead to a premature stop, disrupt canonical splice sites, or lead to insertions/deletions that shift frame. We also genotyped 1 Japanese-specific PTV in 27561 participants from 3 case-control studies (14 286 CHD cases, 13 275 CHD-free controls). We tested association of CETP PTV carrier status with both plasma lipids and CHD. Among 58 469 participants with CETP gene-sequencing data available, average age was 51.5 years and 43% were women; 1 in 975 participants carried a PTV at the CETP gene. Compared with noncarriers, carriers of PTV at CETP had higher high-density lipoprotein cholesterol (effect size, 22.6 mg/dL; 95% confidence interval, 18-27; P<1.0×10-4), lower low-density lipoprotein cholesterol (-12.2 mg/dL; 95% confidence interval, -23 to -0.98; P=0.033), and lower triglycerides (-6.3%; 95% confidence interval, -12 to -0.22; P=0.043). CETP PTV carrier status was associated with reduced risk for CHD (summary odds ratio, 0.70; 95% confidence interval, 0.54-0.90; P=5.1×10-3). CONCLUSIONS: Compared with noncarriers, carriers of PTV at CETP displayed higher high-density lipoprotein cholesterol, lower low-density lipoprotein cholesterol, lower triglycerides, and lower risk for CHD.

Dysfunctional nitric oxide signalling increases risk of myocardial infarction.

Myocardial infarction, a leading cause of death in the Western world, usually occurs when the fibrous cap overlying an atherosclerotic plaque in a coronary artery ruptures. The resulting exposure of blood to the atherosclerotic material then triggers thrombus formation, which occludes the artery. The importance of genetic predisposition to coronary artery disease and myocardial infarction is best documented by the predictive value of a positive family history. Next-generation sequencing in families with several affected individuals has revolutionized mutation identification. Here we report the segregation of two private, heterozygous mutations in two functionally related genes, GUCY1A3 (p.Leu163Phefs*24) and CCT7 (p.Ser525Leu), in an extended myocardial infarction family. GUCY1A3 encodes the α1 subunit of soluble guanylyl cyclase (α1-sGC), and CCT7 encodes CCTη, a member of the tailless complex polypeptide 1 ring complex, which, among other functions, stabilizes soluble guanylyl cyclase. After stimulation with nitric oxide, soluble guanylyl cyclase generates cGMP, which induces vasodilation and inhibits platelet activation. We demonstrate in vitro that mutations in both GUCY1A3 and CCT7 severely reduce α1-sGC as well as ß1-sGC protein content, and impair soluble guanylyl cyclase activity. Moreover, platelets from digenic mutation carriers contained less soluble guanylyl cyclase protein and consequently displayed reduced nitric-oxide-induced cGMP formation. Mice deficient in α1-sGC protein displayed accelerated thrombus formation in the microcirculation after local trauma. Starting with a severely affected family, we have identified a link between impaired soluble-guanylyl-cyclase-dependent nitric oxide signalling and myocardial infarction risk, possibly through accelerated thrombus formation. Reversing this defect may provide a new therapeutic target for reducing the risk of myocardial infarction.

Loss of Cardioprotective Effects at the ADAMTS7 Locus as a Result of Gene-Smoking Interactions.

BACKGROUND: Common diseases such as coronary heart disease (CHD) are complex in etiology. The interaction of genetic susceptibility with lifestyle factors may play a prominent role. However, gene-lifestyle interactions for CHD have been difficult to identify. Here, we investigate interaction of smoking behavior, a potent lifestyle factor, with genotypes that have been shown to associate with CHD risk. METHODS: We analyzed data on 60 919 CHD cases and 80 243 controls from 29 studies for gene-smoking interactions for genetic variants at 45 loci previously reported to be associated with CHD risk. We also studied 5 loci associated with smoking behavior. Study-specific gene-smoking interaction effects were calculated and pooled using fixed-effects meta-analyses. Interaction analyses were declared to be significant at a P value of <1.0×10-3 (Bonferroni correction for 50 tests). RESULTS: We identified novel gene-smoking interaction for a variant upstream of the ADAMTS7 gene. Every T allele of rs7178051 was associated with lower CHD risk by 12% in never-smokers (P=1.3×10-16) in comparison with 5% in ever-smokers (P=2.5×10-4), translating to a 60% loss of CHD protection conferred by this allelic variation in people who smoked tobacco (interaction P value=8.7×10-5). The protective T allele at rs7178051 was also associated with reduced ADAMTS7 expression in human aortic endothelial cells and lymphoblastoid cell lines. Exposure of human coronary artery smooth muscle cells to cigarette smoke extract led to induction of ADAMTS7. CONCLUSIONS: Allelic variation at rs7178051 that associates with reduced ADAMTS7 expression confers stronger CHD protection in never-smokers than in ever-smokers. Increased vascular ADAMTS7 expression may contribute to the loss of CHD protection in smokers.

Genetically determined height and coronary artery disease.

BACKGROUND: The nature and underlying mechanisms of an inverse association between adult height and the risk of coronary artery disease (CAD) are unclear. METHODS: We used a genetic approach to investigate the association between height and CAD, using 180 height-associated genetic variants. We tested the association between a change in genetically determined height of 1 SD (6.5 cm) with the risk of CAD in 65,066 cases and 128,383 controls. Using individual-level genotype data from 18,249 persons, we also examined the risk of CAD associated with the presence of various numbers of height-associated alleles. To identify putative mechanisms, we analyzed whether genetically determined height was associated with known cardiovascular risk factors and performed a pathway analysis of the height-associated genes. RESULTS: We observed a relative increase of 13.5% (95% confidence interval [CI], 5.4 to 22.1; P<0.001) in the risk of CAD per 1-SD decrease in genetically determined height. There was a graded relationship between the presence of an increased number of height-raising variants and a reduced risk of CAD (odds ratio for height quartile 4 versus quartile 1, 0.74; 95% CI, 0.68 to 0.84; P<0.001). Of the 12 risk factors that we studied, we observed significant associations only with levels of low-density lipoprotein cholesterol and triglycerides (accounting for approximately 30% of the association). We identified several overlapping pathways involving genes associated with both development and atherosclerosis. CONCLUSIONS: There is a primary association between a genetically determined shorter height and an increased risk of CAD, a link that is partly explained by the association between shorter height and an adverse lipid profile. Shared biologic processes that determine achieved height and the development of atherosclerosis may explain some of the association. (Funded by the British Heart Foundation and others.).

Do expanded seven-day NHS services improve clinical outcomes? Analysis of comparative institutional performance from the "NHS Services, Seven Days a Week" project 2013-2016.

BACKGROUND: The cause of adverse weekend clinical outcomes remains unknown. In 2013, the "NHS Services, Seven Days a Week" project was initiated to improve access to services across the seven-day week. Three years on, we sought to analyse the impact of such changes across the English NHS. METHODS: Aggregated trust-level data on crude mortality rates, Summary Hospital-Level Mortality Indicator (SHMI), mean length of stay (LOS), A&E admission and four-hour breach rates were obtained from national Hospital Episode Statistics and A&E datasets across the English NHS, excluding mental and community health trusts. Trust annual reports were analysed to determine the presence of any seven-day service reorganisation in 2013-2014. Funnel plots were generated to compare institutional performance and a difference in differences analysis was performed to determine the impact of seven-day changes on clinical outcomes between 2013 and 2014, 2014-2015 and 2015-2016. Data was summarised as mean (SD). RESULTS: Of 159 NHS trusts, 79 (49.7%) instituted seven-day changes in 2013-2014. Crude mortality rates, A&E admission rates and mean LOS remained relatively stable between 2013 and 2016, whilst A&E four-hour breach rates nearly doubled from 5.3 to 9.7%. From 2013 to 2014 to 2014-2015 and 2015-2016, there were no significant differences in the change in crude mortality (2014-2015 p = 0.8, 2015-2016 p = 0.9), SHMI (2014-2015 p = 0.5, 2015-2016 p = 0.5), mean LOS (2014-2015 p = 0.5, 2015-2016 p = 0.4), A&E admission (2014-2015 p = 0.6, 2015-2016 p = 1.0) or four-hour breach rates (2014-2015 p = 0.06, 2015-2016 p = 0.6) between trusts that had implemented seven-day changes compared to those which had not. CONCLUSIONS: Adverse weekend clinical outcomes may not be ameliorated by large scale reorganisations aimed at improving access to health services across the week. Such changes may negatively impact care quality without additional financial investment, as demonstrated by worsening of some outcomes. Detailed prospective research is required to determine whether such reallocation of finite resources is clinically effective.

Association of Rare and Common Variation in the Lipoprotein Lipase Gene With Coronary Artery Disease.

Importance: The activity of lipoprotein lipase (LPL) is the rate-determining step in clearing triglyceride-rich lipoproteins from the circulation. Mutations that damage the LPL gene (LPL) lead to lifelong deficiency in enzymatic activity and can provide insight into the relationship of LPL to human disease. Objective: To determine whether rare and/or common variants in LPL are associated with early-onset coronary artery disease (CAD). Design, Setting, and Participants: In a cross-sectional study, LPL was sequenced in 10 CAD case-control cohorts of the multinational Myocardial Infarction Genetics Consortium and a nested CAD case-control cohort of the Geisinger Health System DiscovEHR cohort between 2010 and 2015. Common variants were genotyped in up to 305 699 individuals of the Global Lipids Genetics Consortium and up to 120 600 individuals of the CARDIoGRAM Exome Consortium between 2012 and 2014. Study-specific estimates were pooled via meta-analysis. Exposures: Rare damaging mutations in LPL included loss-of-function variants and missense variants annotated as pathogenic in a human genetics database or predicted to be damaging by computer prediction algorithms trained to identify mutations that impair protein function. Common variants in the LPL gene region included those independently associated with circulating triglyceride levels. Main Outcomes and Measures: Circulating lipid levels and CAD. Results: Among 46 891 individuals with LPL gene sequencing data available, the mean (SD) age was 50 (12.6) years and 51% were female. A total of 188 participants (0.40%; 95% CI, 0.35%-0.46%) carried a damaging mutation in LPL, including 105 of 32 646 control participants (0.32%) and 83 of 14 245 participants with early-onset CAD (0.58%). Compared with 46 703 noncarriers, the 188 heterozygous carriers of an LPL damaging mutation displayed higher plasma triglyceride levels (19.6 mg/dL; 95% CI, 4.6-34.6 mg/dL) and higher odds of CAD (odds ratio = 1.84; 95% CI, 1.35-2.51; P < .001). An analysis of 6 common LPL variants resulted in an odds ratio for CAD of 1.51 (95% CI, 1.39-1.64; P = 1.1 × 10-22) per 1-SD increase in triglycerides. Conclusions and Relevance: The presence of rare damaging mutations in LPL was significantly associated with higher triglyceride levels and presence of coronary artery disease. However, further research is needed to assess whether there are causal mechanisms by which heterozygous lipoprotein lipase deficiency could lead to coronary artery disease.

The effect of interleukin-1 receptor antagonist therapy on markers of inflammation in non-ST elevation acute coronary syndromes: the MRC-ILA Heart Study.

AIMS: Acute coronary syndromes (ACSs) are driven by inflammation within coronary plaque. Interleukin-1 (IL-1) has an established role in atherogenesis and the vessel-response to injury. ACS patients have raised serum markers of inflammation. We hypothesized that if IL-1 is a driving influence of inflammation in non-ST elevation ACS (NSTE-ACS), IL-1 inhibition would reduce the inflammatory response at the time of ACS. METHODS AND RESULTS: A phase II, double-blinded, randomized, placebo-controlled, study recruited 182 patients with NSTE-ACS, presenting <48 h from onset of chest pain. Treatment was 1:1 allocation to daily, subcutaneous IL-1receptor antagonist (IL-1ra) or placebo for 14 days. Baseline characteristics were well matched. Treatment compliance was 85% at 7 days. The primary endpoint (area-under-the-curve for C-reactive protein over the first 7 days) was: IL-1ra group, 21.98 mg day/L (95%CI 16.31-29.64); placebo group, 43.5 mg day/L (31.15-60.75) (geometric mean ratio = 0.51 mg/L; 95%CI 0.32-0.79; P = 0.0028). In the IL-1ra group, 14-day achieved high-sensitive C-reactive protein (P < 0.0001) and IL-6 levels (P = 0.02) were lower than Day 1. Sixteen days after discontinuation of treatment (Day 30) high-sensitive C-reactive protein levels had risen again in the IL-1ra group [IL-1ra; 3.50 mg/L (2.65-4.62): placebo; 2.21 mg/L (1.67-2.92), P = 0.022]. MACE at Day 30 and 3 months was similar but at 1 year there was a significant excess of events in the IL-1ra group. CONCLUSION: IL-1 drives C-reactive protein elevation at the time of NSTE-ACS. Following 14 days IL-1ra treatment inflammatory markers were reduced. These results show the importance of IL-1 as a target in ACS, but also indicate the need for additional studies with anti-IL-1 therapy in ACS to assess duration and safety. CLINICAL TRIAL REGISTRATION EUCTR: 2006-001767-31-GB: www.clinicaltrialsregister.eu/ctr-search/trial/2006-001767-31/GB.

Mendelian randomization of blood lipids for coronary heart disease.

AIMS: To investigate the causal role of high-density lipoprotein cholesterol (HDL-C) and triglycerides in coronary heart disease (CHD) using multiple instrumental variables for Mendelian randomization. METHODS AND RESULTS: We developed weighted allele scores based on single nucleotide polymorphisms (SNPs) with established associations with HDL-C, triglycerides, and low-density lipoprotein cholesterol (LDL-C). For each trait, we constructed two scores. The first was unrestricted, including all independent SNPs associated with the lipid trait identified from a prior meta-analysis (threshold P < 2 × 10(-6)); and the second a restricted score, filtered to remove any SNPs also associated with either of the other two lipid traits at P ≤ 0.01. Mendelian randomization meta-analyses were conducted in 17 studies including 62,199 participants and 12,099 CHD events. Both the unrestricted and restricted allele scores for LDL-C (42 and 19 SNPs, respectively) associated with CHD. For HDL-C, the unrestricted allele score (48 SNPs) was associated with CHD (OR: 0.53; 95% CI: 0.40, 0.70), per 1 mmol/L higher HDL-C, but neither the restricted allele score (19 SNPs; OR: 0.91; 95% CI: 0.42, 1.98) nor the unrestricted HDL-C allele score adjusted for triglycerides, LDL-C, or statin use (OR: 0.81; 95% CI: 0.44, 1.46) showed a robust association. For triglycerides, the unrestricted allele score (67 SNPs) and the restricted allele score (27 SNPs) were both associated with CHD (OR: 1.62; 95% CI: 1.24, 2.11 and 1.61; 95% CI: 1.00, 2.59, respectively) per 1-log unit increment. However, the unrestricted triglyceride score adjusted for HDL-C, LDL-C, and statin use gave an OR for CHD of 1.01 (95% CI: 0.59, 1.75). CONCLUSION: The genetic findings support a causal effect of triglycerides on CHD risk, but a causal role for HDL-C, though possible, remains less certain.

Inheritance of coronary artery disease in men: an analysis of the role of the Y chromosome.

BACKGROUND: A sexual dimorphism exists in the incidence and prevalence of coronary artery disease--men are more commonly affected than are age-matched women. We explored the role of the Y chromosome in coronary artery disease in the context of this sexual inequity. METHODS: We genotyped 11 markers of the male-specific region of the Y chromosome in 3233 biologically unrelated British men from three cohorts: the British Heart Foundation Family Heart Study (BHF-FHS), West of Scotland Coronary Prevention Study (WOSCOPS), and Cardiogenics Study. On the basis of this information, each Y chromosome was tracked back into one of 13 ancient lineages defined as haplogroups. We then examined associations between common Y chromosome haplogroups and the risk of coronary artery disease in cross-sectional BHF-FHS and prospective WOSCOPS. Finally, we undertook functional analysis of Y chromosome effects on monocyte and macrophage transcriptome in British men from the Cardiogenics Study. FINDINGS: Of nine haplogroups identified, two (R1b1b2 and I) accounted for roughly 90% of the Y chromosome variants among British men. Carriers of haplogroup I had about a 50% higher age-adjusted risk of coronary artery disease than did men with other Y chromosome lineages in BHF-FHS (odds ratio 1·75, 95% CI 1·20-2·54, p=0·004), WOSCOPS (1·45, 1·08-1·95, p=0·012), and joint analysis of both populations (1·56, 1·24-1·97, p=0·0002). The association between haplogroup I and increased risk of coronary artery disease was independent of traditional cardiovascular and socioeconomic risk factors. Analysis of macrophage transcriptome in the Cardiogenics Study revealed that 19 molecular pathways showing strong differential expression between men with haplogroup I and other lineages of the Y chromosome were interconnected by common genes related to inflammation and immunity, and that some of them have a strong relevance to atherosclerosis. INTERPRETATION: The human Y chromosome is associated with risk of coronary artery disease in men of European ancestry, possibly through interactions of immunity and inflammation. FUNDING: British Heart Foundation; UK National Institute for Health Research; LEW Carty Charitable Fund; National Health and Medical Research Council of Australia; European Union 6th Framework Programme; Wellcome Trust.

Interleukin-6 receptor pathways in coronary heart disease: a collaborative meta-analysis of 82 studies.

BACKGROUND: Persistent inflammation has been proposed to contribute to various stages in the pathogenesis of cardiovascular disease. Interleukin-6 receptor (IL6R) signalling propagates downstream inflammation cascades. To assess whether this pathway is causally relevant to coronary heart disease, we studied a functional genetic variant known to affect IL6R signalling. METHODS: In a collaborative meta-analysis, we studied Asp358Ala (rs2228145) in IL6R in relation to a panel of conventional risk factors and inflammation biomarkers in 125,222 participants. We also compared the frequency of Asp358Ala in 51,441 patients with coronary heart disease and in 136,226 controls. To gain insight into possible mechanisms, we assessed Asp358Ala in relation to localised gene expression and to postlipopolysaccharide stimulation of interleukin 6. FINDINGS: The minor allele frequency of Asp358Ala was 39%. Asp358Ala was not associated with lipid concentrations, blood pressure, adiposity, dysglycaemia, or smoking (p value for association per minor allele ≥0·04 for each). By contrast, for every copy of 358Ala inherited, mean concentration of IL6R increased by 34·3% (95% CI 30·4-38·2) and of interleukin 6 by 14·6% (10·7-18·4), and mean concentration of C-reactive protein was reduced by 7·5% (5·9-9·1) and of fibrinogen by 1·0% (0·7-1·3). For every copy of 358Ala inherited, risk of coronary heart disease was reduced by 3·4% (1·8-5·0). Asp358Ala was not related to IL6R mRNA levels or interleukin-6 production in monocytes. INTERPRETATION: Large-scale human genetic and biomarker data are consistent with a causal association between IL6R-related pathways and coronary heart disease. FUNDING: British Heart Foundation; UK Medical Research Council; UK National Institute of Health Research, Cambridge Biomedical Research Centre; BUPA Foundation.

A biophysical model of kiwifruit (Actinidia deliciosa) berry development.

A model of kiwifruit berry development is presented, building on the model of Fishman and Génard used for peach fruit. That model has been extended to incorporate a number of important features of kiwifruit growth. First, the kiwifruit berry is attached to the stem through a pedicel/receptacle complex which contributes significantly to the hydraulic resistance between the stem and the fruit, and this resistance changes considerably during the season. Second, much of the carbohydrate in kiwifruit berries is stored as starch until the fruit matures late in the season, when the starch hydrolyses to soluble sugars. This starch storage has a major effect on the osmotic potential of the fruit, so an existing model of kiwifruit starch dynamics was included in the model. Using previously published approaches, we also included elasticity and extended the modelling period to cover both the cell division and cell expansion phases of growth. The resulting model showed close simulation of field observations of fresh weight, dry matter, starch, and soluble solids in kiwifruit. Comparison with continuous measurements of fruit diameter confirmed that elasticity was needed to adequately simulate observed diurnal variation in fruit size. Sensitivity analyses suggested that the model is particularly sensitive to variation in inputs relating to water (stem water potential and the humidity of the air), and to parameters controlling cell expansion (cell wall extensibility). Some limitations in the model structure were identified, suggesting that a revised model including current apoplastic/symplastic concepts needs to be developed.

Clinical and analytical evaluation of an immunoturbidimetric heart-type fatty acid-binding protein assay.

BACKGROUND: Heart-type fatty acid-binding protein (H-FABP) is a low molecular weight protein involved in the intracellular uptake and buffering of long chain fatty acids in the myocardium. It is an early marker for ACS. We have evaluated the Randox Laboratories immunoturbidimetric assay on a Siemens Advia 1800 analyzer. The assay employs latex particles coated with mouse monoclonal anti-HFABP antibodies to generate turbidity. METHODS: We used redundant patient samples and pools to assess precision, functional sensitivity, limit of detection, linearity, recovery of recombinant H-FABP and interference. We evaluated the 99th centile values and compared H-FABP with troponin in samples routinely received from chest pain patient samples. RESULTS: Precision was typically < 10% and 12.5% at all concentrations for within and between batches. The functional sensitivity was 2.4 µg/L. The assay was linear on dilution over the range 2.76-115 µg/L. Recovery of recombinant H-FABP was approximately 20-25%. No interference was seen with haemoglobin concentrations <1.5 g/L, bilirubin < 250 µg/L and triacylglycerol < 5 mmol/L or rheumatoid factor. The 99th centile value in a reference population with eGFR > 60mL/min/1.73m(2) was 9.1 µg/L with no significant gender difference. H-FABP was measured in routine clinical samples (N = 1310) received for troponin I measurement. Using Siemens TnI > 50 ng/L as an indicator of myocardial damage, the ROC area under curve for H-FABP was 0.82. CONCLUSIONS: The immunoturbidimetric H-FABP assay is robustly designed and shows good analytical performance. It is therefore well suited for use in a routine clinical laboratory.