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Simpkin A.,University of Bristol | Newell J.,HRB Clinical Research Facility
Computational Statistics and Data Analysis | Year: 2013

P-Splines are commonly used for derivative estimation where a non-linear relationship exists between the response and explanatory variables. However, questions about the error of these estimates have arisen. Incorporating an extra penalty term in a P-Spline model is proposed as an improvement when derivative estimation is of primary concern. This additive penalty approach to derivative estimation is shown to improve on the P-Spline estimates based on the results of a simulation study to compare the performance when estimating the first and second derivatives of six simulated functions. A method for generating variability bands for P-Spline derivative estimates with and without an additive penalty is given. The proposed additive penalty variability bands are shown to behave better than their single penalty counterpart. Motivating examples in environmental and sports science are used to demonstrate the need for accurate derivative estimates and the benefit of using an additional penalty term to this end. © 2013 Elsevier B.V. All rights reserved. Source

Graux C.,Mont Godinne University Hospital | Sonet A.,Mont Godinne University Hospital | Maertens J.,University Hospital Gasthuisberg | Duyster J.,TU Munich | And 15 more authors.
Leukemia Research | Year: 2013

A phase I dose-escalation study of MSC1992371A, an oral aurora kinase inhibitor, was carried out in patients with hematologic malignancies. Patients received escalating doses either on days 1-3 and 8-10 (n=36) or on days 1-6 (n=39) of a 21-day cycle. The maximum tolerated doses were 37 and 28mg/m2/day, respectively. Dose-limiting toxicities included severe neutropenia with infection and sepsis, mucositis/stomatitis, and diarrhea. Complete responses occurred in 3 patients. Four disease-specific expansion cohorts then received the dose and schedule dictated by the escalation phase but the study was prematurely discontinued due to hematologic and gastrointestinal toxicity at clinically effective doses. © 2013 Elsevier Ltd. Source

Connolly S.J.,Hamilton Health Sciences | Eikelboom J.,Hamilton Health Sciences | Joyner C.,University of Toronto | Diener H.-C.,University of Duisburg - Essen | And 26 more authors.
New England Journal of Medicine | Year: 2011

BACKGROUND: Vitamin K antagonists have been shown to prevent stroke in patients with atrial fibrillation. However, many patients are not suitable candidates for or are unwilling to receive vitamin K antagonist therapy, and these patients have a high risk of stroke. Apixaban, a novel factor Xa inhibitor, may be an alternative treatment for such patients. METHODS: In a double-blind study, we randomly assigned 5599 patients with atrial fibrillation who were at increased risk for stroke and for whom vitamin K antagonist therapy was unsuitable to receive apixaban (at a dose of 5 mg twice daily) or aspirin (81 to 324 mg per day), to determine whether apixaban was superior. The mean follow up period was 1.1 years. The primary outcome was the occurrence of stroke or systemic embolism. RESULTS: Before enrollment, 40% of the patients had used a vitamin K antagonist. The data and safety monitoring board recommended early termination of the study because of a clear benefit in favor of apixaban. There were 51 primary outcome events (1.6% per year) among patients assigned to apixaban and 113 (3.7% per year) among those assigned to aspirin (hazard ratio with apixaban, 0.45; 95% confidence interval [CI], 0.32 to 0.62; P<0.001). The rates of death were 3.5% per year in the apixaban group and 4.4% per year in the aspirin group (hazard ratio, 0.79; 95% CI, 0.62 to 1.02; P = 0.07). There were 44 cases of major bleeding (1.4% per year) in the apixaban group and 39 (1.2% per year) in the aspirin group (hazard ratio with apixaban, 1.13; 95% CI, 0.74 to 1.75; P = 0.57); there were 11 cases of intracranial bleeding with apixaban and 13 with aspirin. The risk of a first hospitalization for cardiovascular causes was reduced with apixaban as compared with aspirin (12.6% per year vs. 15.9% per year, P<0.001). The treatment effects were consistent among important subgroups. CONCLUSIONS: In patients with atrial fibrillation for whom vitamin K antagonist therapy was unsuitable, apixaban reduced the risk of stroke or systemic embolism without significantly increasing the risk of major bleeding or intracranial hemorrhage. Copyright © 2011 Massachusetts Medical Society. Source

Zafar H.,National University of Ireland | Sharif F.,University Hospital | Sharif F.,HRB Clinical Research Facility | Sharif F.,National University of Ireland | And 2 more authors.
International Heart Journal | Year: 2014

Frequency domain optical coherence tomography (FD-OCT) provides cross-sectional images of coronary arteries and deployed stents with micron resolution and measures lumen dimensions with excellent reproducibility. FD-OCT combined with a blood flow resistances model can overcome many limitations of conventional measures of stenosis severity based on quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS). The aim of this feasibility study was to investigate the relationship between pressure derived fractional flow reserve (FFR) and FD-OCT derived FFR, a new method for quantitative measure of stenosis severity that estimates the blood flow resistance and microvascular resistance of the vessel segments imaged by FD-OCT. A total of 26 coronary stenoses in 20 patients were studied consecutively with QCA, pressure derived FFR, and FD-OCT. There was a moderate but significant correlation between pressure derived FFR and FD-OCT derived FFR (r = 0.69, P < 0.001). Bland-Altman analysis showed that the mean differences between pressure derived FFR and FD-OCT derived FFR were 0.05 ± 0.14 (limits of agreement: -0.09 to 0.19). The root mean square error (RMSE) between FD-OCT derived FFR and pressure derived FFR was found to be ± 0.087 FFR units. FD-OCT derived FFR has the potential to become a valuable tool for the assessment of coronary artery stenosis. Source

O'Brien B.,National University of Ireland | Zafar H.,University of Science and Arts of Iran | Ibrahim A.,University Hospital Galway | Zafar J.,Government College University Lahore | And 3 more authors.
Annals of Biomedical Engineering | Year: 2015

This paper reviews the current state of the art for coronary stent materials and surface coatings, with an emphasis on new technologies that followed on from first-generation bare metal and drug-eluting stents. These developments have been driven mainly by the need to improve long term outcomes, including late stent thrombosis. Biodegradable drug-eluting coatings aim to address the long term effects of residual durable polymer after drug elution; the SYNERGY, BioMatrix, and Nobori stents are all promising devices in this category, with minimal polymer through the use of abluminal coatings. Textured stent surfaces have been used to attached drug directly, without polymer; the Yukon Choice and BioFreedom stents have some promising data in this category, while a hydroxyapatite textured surface has had less success. The use of drug-filled reservoirs looked promising initially but the NEVO device has experienced both technical and commercial set-backs. However this approach may eventually make it to market if trials with the Drug-Filled Stent prove to be successful. Non-pharmacological coatings such as silicon carbide, carbon, and titanium–nitride-oxide are also proving to have potential to provide better performance than BMS, without some of the longer term issues associated with DES. In terms of biological coatings, the Genous stent which promotes attachment of endothelial progenitor cells has made good progress while gene-eluting stents still have some practical challenges to overcome. Perhaps the most advancement has been in the field of biodegradable stents. The BVS PLLA device is now seeing increasing clinical use in many complex indications while magnesium stents continue to make steady advancements. © 2015 Biomedical Engineering Society Source

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