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Darrel Francis

Alex A T Bui, John Darrell Van Horn
In our era of digital biomedicine, data take many forms, from "omics" to imaging, mobile health (mHealth), and electronic health records (EHRs). With the availability of more efficient digital collection methods, scientists in many domains now find themselves confronting ever larger sets of data and trying to make sense of it all (1-4). Indeed, data which used to be considered large now seems small as the amount of data now being collected in a single day by an investigator can surpass what might have been generated over his/her career even a decade ago (e...
March 30, 2017: Journal of Biomedical Informatics
Matthew J Shun-Shin, Sean L Zheng, Graham D Cole, James P Howard, Zachary I Whinnett, Darrel P Francis
Aims: Primary prevention implantable cardioverter defibrillators (ICDs) are established therapy for reducing mortality in patients with left ventricular systolic dysfunction and ischaemic heart disease (IHD). However, their efficacy in patients without IHD has been controversial. We undertook a meta-analysis of the totality of the evidence. Methods and results: We systematically identified all RCTs comparing ICD vs. no ICD in primary prevention. Eligible RCTs were those that recruited patients with left ventricular dysfunction, reported all-cause mortality, and presented their results stratified by the presence of IHD (or recruited only those with or without)...
February 21, 2017: European Heart Journal
Niti M Dhutia, Massoud Zolgharni, Michael Mielewczik, Madalina Negoita, Stefania Sacchi, Karikaran Manoharan, Darrel P Francis, Graham D Cole
Current guidelines for measuring cardiac function by tissue Doppler recommend using multiple beats, but this has a time cost for human operators. We present an open-source, vendor-independent, drag-and-drop software capable of automating the measurement process. A database of ~8000 tissue Doppler beats (48 patients) from the septal and lateral annuli were analyzed by three expert echocardiographers. We developed an intensity- and gradient-based automated algorithm to measure tissue Doppler velocities. We tested its performance against manual measurements from the expert human operators...
February 20, 2017: International Journal of Cardiovascular Imaging
Wilfred Ngwa, Francis Boateng, Rajiv Kumar, Darrell J Irvine, Silvia Formenti, Twalib Ngoma, Carsten Herskind, Marlon R Veldwijk, Georg Lars Hildenbrand, Michael Hausmann, Frederik Wenz, Juergen Hesser
Radiation therapy (RT) is a crucial component of cancer care, used in the treatment of over 50% of cancer patients. Patients undergoing image guided RT or brachytherapy routinely have inert RT biomaterials implanted into their tumors. The single function of these RT biomaterials is to ensure geometric accuracy during treatment. Recent studies have proposed that the inert biomaterials could be upgraded to "smart" RT biomaterials, designed to do more than 1 function. Such smart biomaterials include next-generation fiducial markers, brachytherapy spacers, and balloon applicators, designed to respond to stimuli and perform additional desirable functions like controlled delivery of therapy-enhancing payloads directly into the tumor subvolume while minimizing normal tissue toxicities...
March 1, 2017: International Journal of Radiation Oncology, Biology, Physics
Christopher Cook, Yousif Ahmad, Ricardo Petraco, Sukhjinder Nijjer, Matthew Shun-Shin, Rasha Al-Lamee, Yuetsu Kikuta, Yasutsugu Shiono, Jamil Mayet, Darrel Francis, Sayan Sen, Justin Davies
No abstract text is available yet for this article.
November 1, 2016: Journal of the American College of Cardiology
Jan DE Pooter, Milad El Haddad, Marc DE Buyzere, Hernandez Alfonso Aranda, Richard Cornelussen, Berthold Stegemann, Christopher A Rinaldi, Maciej Sterlinski, Adam Sokal, Darrel P Francis, Luc Jordaens, Roland X Stroobandt, Frederic VAN Heuverswyn, Frank Timmermans
INTRODUCTION: Vectorcardiographic (VCG) QRS area of left bundle branch block (LBBB) predicts acute hemodynamic response in cardiac resynchronization therapy (CRT) patients. We hypothesized that changes in QRS area occurring with biventricular pacing (BV) might predict acute hemodynamic CRT response (AHR). METHODS AND RESULTS: VCGs of 624 BV paced electrocardiograms (25 LBBB patients with 35 different pacing configurations) were calculated according to Frank's orthogonal lead system...
February 2017: Journal of Cardiovascular Electrophysiology
Claire E Raphael, Robert Cooper, Kim H Parker, Julian Collinson, Vassilis Vassiliou, Dudley J Pennell, Ranil de Silva, Li Yueh Hsu, Anders M Greve, Sukh Nijjer, Chris Broyd, Aamir Ali, Jennifer Keegan, Darrel P Francis, Justin E Davies, Alun D Hughes, Andrew Arai, Michael Frenneaux, Rod H Stables, Carlo Di Mario, Sanjay K Prasad
BACKGROUND: Angina is common in hypertrophic cardiomyopathy (HCM) and is associated with abnormal myocardial perfusion. Wave intensity analysis improves the understanding of the mechanics of myocardial ischemia. OBJECTIVES: Wave intensity analysis was used to describe the mechanisms underlying perfusion abnormalities in patients with HCM. METHODS: Simultaneous pressure and flow were measured in the proximal left anterior descending artery in 33 patients with HCM and 20 control patients at rest and during hyperemia, allowing calculation of wave intensity...
October 11, 2016: Journal of the American College of Cardiology
Gabriella Captur, Audrey L Karperien, Alun D Hughes, Darrel P Francis, James C Moon
For clinicians grappling with quantifying the complex spatial and temporal patterns of cardiac structure and function (such as myocardial trabeculae, coronary microvascular anatomy, tissue perfusion, myocyte histology, electrical conduction, heart rate, and blood-pressure variability), fractal analysis is a powerful, but still underused, mathematical tool. In this Perspectives article, we explain some fundamental principles of fractal geometry and place it in a familiar medical setting. We summarize studies in the cardiovascular sciences in which fractal methods have successfully been used to investigate disease mechanisms, and suggest potential future clinical roles in cardiac imaging and time series measurements...
January 2017: Nature Reviews. Cardiology
Erin Janssen, Mira Tohme, Mona Hedayat, Marion Leick, Sudha Kumari, Narayanaswamy Ramesh, Michel J Massaad, Sumana Ullas, Veronica Azcutia, Christopher C Goodnow, Katrina L Randall, Qi Qiao, Hao Wu, Waleed Al-Herz, Dianne Cox, John Hartwig, Darrell J Irvine, Francis W Luscinskas, Raif S Geha
Wiskott-Aldrich syndrome (WAS) is associated with mutations in the WAS protein (WASp), which plays a critical role in the initiation of T cell receptor-driven (TCR-driven) actin polymerization. The clinical phenotype of WAS includes susceptibility to infection, allergy, autoimmunity, and malignancy and overlaps with the symptoms of dedicator of cytokinesis 8 (DOCK8) deficiency, suggesting that the 2 syndromes share common pathogenic mechanisms. Here, we demonstrated that the WASp-interacting protein (WIP) bridges DOCK8 to WASp and actin in T cells...
October 3, 2016: Journal of Clinical Investigation
Scott A Sands, Yoseph Mebrate, Bradley A Edwards, Shamim Nemati, Charlotte H Manisty, Akshay S Desai, Andrew Wellman, Keith Willson, Darrel P Francis, James P Butler, Atul Malhotra
RATIONALE: In patients with chronic heart failure, daytime oscillatory breathing at rest is associated with a high risk of mortality. Experimental evidence, including exaggerated ventilatory responses to CO2 and prolonged circulation time, implicates the ventilatory control system and suggests feedback instability (loop gain > 1) is responsible. However, daytime oscillatory patterns often appear remarkably irregular versus classic instability (Cheyne-Stokes respiration), suggesting our mechanistic understanding is limited...
January 15, 2017: American Journal of Respiratory and Critical Care Medicine
Yousif Ahmad, Christopher Cook, Matthew Shun-Shin, Ashwin Balu, Daniel Keene, Sukhjinder Nijjer, Ricardo Petraco, Christopher S Baker, Iqbal S Malik, Michael F Bellamy, Amarjit Sethi, Ghada W Mikhail, Mahmud Al-Bustami, Masood Khan, Raffi Kaprielian, Rodney A Foale, Jamil Mayet, Justin E Davies, Darrel P Francis, Sayan Sen
BACKGROUND: Patients presenting with ST-elevation myocardial infarction commonly have multi-vessel coronary artery disease. After the culprit artery is treated, the optimal treatment strategy for the residual disease is not yet defined. Large observational studies suggest that treatment of residual disease should be deferred but smaller randomised controlled trials (RCTs) suggest multi-vessel primary percutaneous coronary intervention (MV-PPCI) at the time of STEMI is safe. We examine if allocation bias of high-risk patients could explain the conflicting results between observational studies and RCTs and aim to resolve the paradox between the two...
November 1, 2016: International Journal of Cardiology
Siana Jones, Joost Lumens, S M Afzal Sohaib, Judith A Finegold, Prapa Kanagaratnam, Mark Tanner, Edward Duncan, Philip Moore, Francisco Leyva, Mike Frenneaux, Mark Mason, Alun D Hughes, Darrel P Francis, Zachary I Whinnett
AIMS: Cardiac resynchronization therapy (CRT) may exert its beneficial haemodynamic effect by improving ventricular synchrony and improving atrioventricular (AV) timing. The aim of this study was to establish the relative importance of the mechanisms through which CRT improves cardiac function and explore the potential for additional improvements with improved ventricular resynchronization. METHODS AND RESULTS: We performed simulations using the CircAdapt haemodynamic model and performed haemodynamic measurements while adjusting AV delay, at low and high heart rates, in 87 patients with CRT devices...
July 13, 2016: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
Raffaello Cimbro, Francis C Peterson, Qingbo Liu, Christina Guzzo, Peng Zhang, Huiyi Miao, Donald Van Ryk, Xavier Ambroggio, Darrell E Hurt, Luca De Gioia, Brian F Volkman, Michael A Dolan, Paolo Lusso
Tyrosine sulfation is a post-translational modification that facilitates protein-protein interaction. Two sulfated tyrosines (Tys173 and Tys177) were recently identified within the second variable (V2) loop of the major HIV-1 envelope glycoprotein, gp120, and shown to contribute to stabilizing the intramolecular interaction between V2 and the third variable (V3) loop. Here, we report that tyrosine-sulfated peptides derived from V2 act as structural and functional mimics of the CCR5 N-terminus and potently block HIV-1 infection...
August 2016: EBioMedicine
Arjun K Ghosh, Darrel P Francis, Nishi Chaturvedi, Diana Kuh, Jamil Mayet, Alun D Hughes, Rebecca J Hardy
BACKGROUND: Clinical practice evaluates cardiovascular risk based on current risk factor (RF) levels [Blood pressure (BP), body mass index (BMI) and glycaemic control] largely disregarding previous risk-factor history over the totality of the life course. RFs are related to contemporaneous echocardiographic measures of cardiac structure and function which in turn are independently related to cardiovascular morbidity and mortality in cross-sectional studies. However, the effect of lifetime or earlier RF history on future echocardiographic changes has never been systematically examined...
July 2014: Journal of Cardiology and Therapeutics
Madalina Negoita, Massoud Zolgharni, Elham Dadkho, Matteo Pernigo, Michael Mielewczik, Graham D Cole, Niti M Dhutia, Darrel P Francis
OBJECTIVES: To determine the optimal frame rate at which reliable heart walls velocities can be assessed by speckle tracking. BACKGROUND: Assessing left ventricular function with speckle tracking is useful in patient diagnosis but requires a temporal resolution that can follow myocardial motion. In this study we investigated the effect of different frame rates on the accuracy of speckle tracking results, highlighting the temporal resolution where reliable results can be obtained...
September 1, 2016: International Journal of Cardiology
Maciej Sterliński, Adam Sokal, Radosław Lenarczyk, Frederic Van Heuverswyn, C Aldo Rinaldi, Marc Vanderheyden, Vladimir Khalameizer, Darrel Francis, Joeri Heynens, Berthold Stegemann, Richard Cornelussen
INTRODUCTION: Recent efforts to increase CRT response by multiSPOT pacing (MSP) from multiple bipols on the same left ventricular lead are still inconclusive. AIM: The Left Ventricular (LV) MultiSPOTpacing for CRT (iSPOT) study compared the acute hemodynamic response of MSP pacing by using 3 electrodes on a quadripolar lead compared with conventional biventricular pacing (BiV). METHODS: Patients with left bundle branch block (LBBB) underwent an acute hemodynamic study to determine the %change in LV+dP/dtmax from baseline atrial pacing compared to the following configurations: BiV pacing with the LV lead in a one of lateral veins, while pacing from the distal, mid, or proximal electrode and all 3 electrodes together (i...
2016: PloS One
Paulette I Abbas, Jennifer E Dietrich, Jessica A Francis, Mary L Brandt, Darrell L Cass, Monica E Lopez
STUDY OBJECTIVE: To evaluate outcomes of children after ovarian-sparing surgery (OSS) for non-neoplastic and benign neoplastic ovarian lesions. DESIGN: Retrospective cohort study from January 2003 to January 2012. SETTING: Single, high-volume, tertiary care hospital. PARTICIPANTS: Children 18 years of age and younger. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Postoperative complications and tumor recurrence after OSS...
October 2016: Journal of Pediatric and Adolescent Gynecology
Christopher M Cook, Yousif Ahmad, Matthew J Shun-Shin, Sukhjinder Nijjer, Ricardo Petraco, Rasha Al-Lamee, Jamil Mayet, Darrel P Francis, Sayan Sen, Justin E Davies
BACKGROUND: Small drifts in intracoronary pressure measurements (±2 mm Hg) can affect stenosis categorization using pressure indices. This has not previously been assessed for fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and whole-cycle distal pressure/proximal pressure (Pd/Pa) indices. METHODS AND RESULTS: Four hundred forty-seven stenoses were assessed with FFR, iFR, and whole-cycle Pd/Pa. Cut point values for significance were predefined as ≤0...
April 2016: Circulation. Cardiovascular Interventions
Arjun Kumar Ghosh, Alun David Hughes, Darrel Francis, Nishi Chaturvedi, Denis Pellerin, John Deanfield, Diana Kuh, Jamil Mayet, Rebecca Hardy
OBJECTIVES: High blood pressure (BP) is associated with diastolic dysfunction, but the consequence of elevated BP over the adult life course on diastolic function is unknown. We hypothesised that high BP in earlier adulthood would be associated with impaired diastolic function independent of current BP. METHODS: Participants in the Medical Research Council National Survey of Health and Development birth cohort (n=1653) underwent investigations including echocardiography at age 60-64 years...
September 1, 2016: Heart: Official Journal of the British Cardiac Society
Judith A Finegold, Matthew J Shun-Shin, Graham D Cole, Saman Zaman, Annette Maznyczka, Sameer Zaman, Rasha Al-Lamee, Siqin Ye, Darrel P Francis
OBJECTIVE: When advising patients about possible initiation of primary prevention treatment, clinicians currently do not have information on expected impact on lifespan, nor how much this increment differs between individuals. METHODS: First, UK cardiovascular and non-cardiovascular mortality data were used to calculate the mean lifespan gain from an intervention (such as a statin) that reduces cardiovascular mortality by 30%. Second, a new method was developed to calculate the probability distribution of lifespan gain...
2016: Open Heart
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