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Clinical trial simulation

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https://www.readbyqxmd.com/read/29777595/a-ring-based-compensator-imrt-system-optimized-for-low-and-middle-income-countries-design-and-treatment-planning-study
#1
Jonathon Van Schelt, Daniel Smith, Nicholas Fong, Dolla Toomeh, Patricia A Sponseller, Derek W Brown, Meghan W Macomber, Nina A Mayr, Shilpen Patel, Adam Shulman, G V Subrahmanyam, K Govindarajan, Eric C Ford
PURPOSE: We propose a novel compensator-based IMRT system designed to provide a simple, reliable, and cost-effective adjunct technology, with the goal of expanding global access to advanced radiotherapy techniques. The system would employ easily-reusable tungsten bead compensators that operate independent of a gantry (e.g. mounted in a ring around the patient). Thereby the system can be retrofitted to existing linac and cobalt teletherapy units. This study explores the quality of treatment plans from the proposed system and the dependence on associated design parameters...
May 19, 2018: Medical Physics
https://www.readbyqxmd.com/read/29777394/biomechanical-impact-of-wrong-positioning-of-a-dedicated-stent-for-coronary-bifurcations-a-virtual-bench-testing-study
#2
Claudio Chiastra, Maik J Grundeken, Carlos Collet, Wei Wu, Joanna J Wykrzykowska, Giancarlo Pennati, Gabriele Dubini, Francesco Migliavacca
The treatment of coronary bifurcations is challenging for interventional cardiologists. The Tryton stent (Tryton Medical, Inc., USA) is one of the few devices specifically designed for coronary bifurcations that underwent large clinical trials. Although the manufacturer provides specific recommendations to position the stent in the bifurcation side branch (SB) according to four radio-opaque markers under angiographic guidance, wrong device positioning may accidentally occur. In this study, the virtual bench testing approach was used to investigate the impact of wrong positioning of the Tryton stent in coronary bifurcations in terms of geometrical and biomechanical criteria...
May 17, 2018: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/29775553/influence-of-photobiomodulation-therapy-on-gingivitis-induced-by-multi-bracket-appliances-a-split-mouth-randomized-controlled-trial
#3
Steffen Stein, Michael Schauseil, Andreas Hellak, Heike Korbmacher-Steiner, Andreas Braun
OBJECTIVE: The objective of this split-mouth trial was to investigate the influence of photobiomodulation therapy (PBMT) on adjuvant treatment of gingivitis induced by multi-bracket appliances, after bracket debonding and professional tooth cleaning. MATERIALS AND METHODS: Thirteen patients (mean age 16.15 years; standard deviation ±2.12 years) who had completed active orthodontic treatment with fixed orthodontic appliances in an orthodontic clinic were included on a randomized basis...
May 18, 2018: Photomedicine and Laser Surgery
https://www.readbyqxmd.com/read/29775203/optimal-two-stage-dynamic-treatment-regimes-from-a-classification-perspective-with-censored-survival-data
#4
Rebecca Hager, Anastasios A Tsiatis, Marie Davidian
Clinicians often make multiple treatment decisions at key points over the course of a patient's disease. A dynamic treatment regime is a sequence of decision rules, each mapping a patient's observed history to the set of available, feasible treatment options at each decision point, and thus formalizes this process. An optimal regime is one leading to the most beneficial outcome on average if used to select treatment for the patient population. We propose a method for estimation of an optimal regime involving two decision points when the outcome of interest is a censored survival time, which is based on maximizing a locally efficient, doubly robust, augmented inverse probability weighted estimator for average outcome over a class of regimes...
May 18, 2018: Biometrics
https://www.readbyqxmd.com/read/29774168/evaluating-the-potential-for-maximized-t-cell-redistribution-entropy-to-improve-abscopal-responses-to-radiotherapy
#5
Rachel Walker, Jonathan D Schoenfeld, Shari Pilon-Thomas, Jan Poleszczuk, Heiko Enderling
The potential for local radiation therapy to elicit systemic (abscopal) anti-tumor immune responses has been receiving a significant amount of attention over the last decade. We recently developed a mathematical framework designed to simulate the systemic dissemination of activated T cells among multiple metastatic sites. This framework allowed the identification of non-intuitive patterns of T cell redistribution after localized therapy, and offered suggestions as to the optimal site to irradiate in order to increase the magnitude of an immune-mediated abscopal response...
September 2017: Convergent Science Physical Oncology
https://www.readbyqxmd.com/read/29770730/testing-hypotheses-under-adaptive-randomization-with-continuous-covariates-in-clinical-trials
#6
Xiaoming Li, Jianhui Zhou, Feifang Hu
Covariate-adaptive designs are widely used to balance covariates and maintain randomization in clinical trials. Adaptive designs for discrete covariates and their asymptotic properties have been well studied in the literature. However, important continuous covariates are often involved in clinical studies. Simply discretizing or categorizing continuous covariates can result in loss of information. The current understanding of adaptive designs with continuous covariates lacks a theoretical foundation as the existing works are entirely based on simulations...
January 1, 2018: Statistical Methods in Medical Research
https://www.readbyqxmd.com/read/29770729/group-sequential-designs-for-negative-binomial-outcomes
#7
Tobias Mütze, Ekkehard Glimm, Heinz Schmidli, Tim Friede
Count data and recurrent events in clinical trials, such as the number of lesions in magnetic resonance imaging in multiple sclerosis, the number of relapses in multiple sclerosis, the number of hospitalizations in heart failure, and the number of exacerbations in asthma or in chronic obstructive pulmonary disease (COPD) are often modeled by negative binomial distributions. In this manuscript, we study planning and analyzing clinical trials with group sequential designs for negative binomial outcomes. We propose a group sequential testing procedure for negative binomial outcomes based on Wald statistics using maximum likelihood estimators...
January 1, 2018: Statistical Methods in Medical Research
https://www.readbyqxmd.com/read/29769198/mathematical-modeling-predicts-response-to-chemotherapy-and-drug-combinations-in-ovarian-cancer
#8
Emilia Kozłowska, Anniina Färkkilä, Tuulia Vallius, Olli Carpén, Jukka Kemppainen, Seija Grénman, Rainer Lehtonen, Johanna Hynninen, Sakari Hietanen, Sampsa Hautaniemi
Platinum-based chemotherapy constitutes the backbone of clinical care in advanced solid cancers such as high-grade serous ovarian cancer (HGSOC) and has prolonged survival of millions of cancer patients. Most of these patients, however, become resistant to chemotherapy, which generally leads to a fatal refractory disease. We present a comprehensive stochastic mathematical model and simulator approach to describe platinum resistance and standard-of-care (SOC) therapy in HGSOC. We used pre- and post-treatment clinical data, including 18F-FDG-PET/CT images, to reliably estimate the model parameters and simulate "virtual HGSOC patients...
May 16, 2018: Cancer Research
https://www.readbyqxmd.com/read/29768512/infant-cpap-for-low-income-countries-an-experimental-comparison-of-standard-bubble-cpap-and-the-pumani-system
#9
Markus Falk, Snorri Donaldsson, Thomas Drevhammar
INTRODUCTION: Access to inexpensive respiratory support to newborn infants improves survival in low-income countries. Standard bubble continuous positive airway pressure (CPAP) has been extensively used worldwide for more than 30 years. One project aimed at providing affordable CPAP is the Pumani system developed by Rice 360°. Compared to standard bubble CPAP the system has an unconventional design. The aim was to compare the Pumani system with two traditional bubble CPAP systems, focusing on in-vitro performance and safety...
2018: PloS One
https://www.readbyqxmd.com/read/29763812/computation-of-hip-rotation-kinematics-retrospectively-using-functional-knee-calibration-during-gait
#10
Morgan Sangeux
BACKGROUND: Hip rotation kinematics during gait is a key parameter to support clinical decision making, for example in children with lower limb torsional deformities. However, hip rotation kinematics is also one of the least repeatable parameter because it is difficult to locate the position of the medio-lateral axis of the femur. Functional knee calibration provides an alternative to locate the medio-lateral axis of the femur and may be performed retrospectively, using the movement of the knee joint during gait...
May 8, 2018: Gait & Posture
https://www.readbyqxmd.com/read/29761824/impact-of-cardio-synchronous-brain-pulsations-on-monte-carlo-calculated-doses-for-synchrotron-micro-and-mini-beam-radiation-therapy
#11
Francisco Manchado de Sola, Manuel Vilches, Yolanda Prezado, Antonio M Lallena
PURPOSE: To assess the effects of brain movements induced by heartbeat on dose distributions in synchrotron micro- and mini-beam radiaton therapy and to develop a model to help guide decisions and planning for future clinical trials. METHODS: The Monte Carlo code PENELOPE was used to simulate the irradiation of a human head phantom with a variety of micro- and mini-beam arrays, with beams narrower than 100 μm and above 500 μm, respectively, and with radiation fields of 1cm × 2cm and 2cm × 2cm...
May 15, 2018: Medical Physics
https://www.readbyqxmd.com/read/29761523/a-novel-cognitive-disease-progression-model-for-clinical-trials-in-autosomal-dominant-alzheimer-s-disease
#12
Guoqiao Wang, Scott Berry, Chengjie Xiong, Jason Hassenstab, Melanie Quintana, Eric M McDade, Paul Delmar, Matteo Vestrucci, Gopalan Sethuraman, Randall J Bateman
Clinical trial outcomes for Alzheimer's disease are typically analyzed by using the mixed model for repeated measures (MMRM) or similar models that compare an efficacy scale change from baseline between treatment arms with or without participants' disease stage as a covariate. The MMRM focuses on a single-point fixed follow-up duration regardless of the exposure for each participant. In contrast to these typical models, we have developed a novel semiparametric cognitive disease progression model (DPM) for autosomal dominant Alzheimer's disease based on the Dominantly Inherited Alzheimer Network (DIAN) observational study...
May 14, 2018: Statistics in Medicine
https://www.readbyqxmd.com/read/29760728/mesenchymal-stromal-cells-cultured-in-serum-from-heart-failure-patients-are-more-resistant-to-simulated-chronic-and-acute-stress
#13
Timo Z Nazari-Shafti, Zhiyi Xu, Andreas Matthäus Bader, Georg Henke, Kristin Klose, Volkmar Falk, Christof Stamm
Despite regulatory issues surrounding the use of animal-derived cell culture supplements, most clinical cardiac cell therapy trials using mesenchymal stromal cells (MSCs) still rely on fetal bovine serum (FBS) for cell expansion before transplantation. We sought to investigate the effect of human serum from heart failure patients (HFS) on cord blood MSCs (CB-MSCs) during short-term culture under regular conditions and during simulated acute and chronic stress. Cell survival, proliferation, metabolic activity, and apoptosis were quantified, and gene expression profiles of selected apoptosis and cell cycle regulators were determined...
2018: Stem Cells International
https://www.readbyqxmd.com/read/29760204/model-based-meta-analysis-to-evaluate-optimal-doses-of-direct-oral-factor-xa-inhibitors-in-atrial-fibrillation-patients
#14
Hideki Yoshioka, Hiromi Sato, Hiroto Hatakeyama, Akihiro Hisaka
The noninferiority of direct oral factor Xa (FXa) inhibitors (rivaroxaban, apixaban, and edoxaban) in treatment of atrial fibrillation were demonstrated compared with warfarin by several large clinical trials; however, subsequent meta-analyses reported a higher risk of major bleeding with rivaroxaban than with the other FXa inhibitors. In the present study, we first estimated the changes of prothrombin time (PT) in 5 randomized trials based on reported population pharmacokinetic and pharmacodynamic models and then carried out a model-based meta-analysis to obtain models describing the relationship between PT changes and the event rates of ischemic stroke/systemic embolism (SE) and of major bleeding...
May 22, 2018: Blood Advances
https://www.readbyqxmd.com/read/29748784/algorithm-for-improving-psychophysical-threshold-estimates-by-detecting-sustained-inattention-in-experiments-using-pest
#15
Mike D Rinderknecht, Raffaele Ranzani, Werner L Popp, Olivier Lambercy, Roger Gassert
Psychophysical procedures are applied in various fields to assess sensory thresholds. During experiments, sampled psychometric functions are usually assumed to be stationary. However, perception can be altered, for example by loss of attention to the presentation of stimuli, leading to biased data, which results in poor threshold estimates. The few existing approaches attempting to identify non-stationarities either detect only whether there was a change in perception, or are not suitable for experiments with a relatively small number of trials (e...
May 10, 2018: Attention, Perception & Psychophysics
https://www.readbyqxmd.com/read/29747928/monte-carlo-simulation-tool-for-online-treatment-monitoring-in-hadrontherapy-with-in-beam-pet-a-patient-study
#16
E Fiorina, V Ferrero, F Pennazio, G Baroni, G Battistoni, N Belcari, P Cerello, N Camarlinghi, M Ciocca, A Del Guerra, M Donetti, A Ferrari, S Giordanengo, G Giraudo, A Mairani, M Morrocchi, C Peroni, A Rivetti, M D Da Rocha Rolo, S Rossi, V Rosso, P Sala, G Sportelli, S Tampellini, F Valvo, R Wheadon, M G Bisogni
Hadrontherapy is a method for treating cancer with very targeted dose distributions and enhanced radiobiological effects. To fully exploit these advantages, in vivo range monitoring systems are required. These devices measure, preferably during the treatment, the secondary radiation generated by the beam-tissue interactions. However, since correlation of the secondary radiation distribution with the dose is not straightforward, Monte Carlo (MC) simulations are very important for treatment quality assessment...
May 7, 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/29746711/a-monte-carlo-simulation-approach-for-beta-lactam-dosing-in-critically-ill-patients-receiving-prolonged-intermittent-renal-replacement-therapy
#17
Soo Min Jang, Katherine N Gharibian, Susan J Lewis, William H Fissell, Ashita J Tolwani, Bruce A Mueller
Cefepime, ceftazidime, and piperacillin/tazobactam are commonly used beta-lactam antibiotics in the critical care setting. For critically ill patients receiving prolonged intermittent renal replacement therapy (PIRRT), limited pharmacokinetic data are available to inform clinicians on the dosing of these agents. Monte Carlo simulations (MCS) can be used to guide drug dosing when pharmacokinetic trials are not feasible. For each antibiotic, MCS using previously published pharmacokinetic data derived from critically ill patients was used to evaluate multiple dosing regimens in 4 different prolonged intermittent renal replacement therapy effluent rates and prolonged intermittent renal replacement therapy duration combinations (4 L/h × 10 hours or 5 L/h × 8 hours in hemodialysis and hemofiltration modes)...
May 10, 2018: Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/29746707/population-pharmacokinetics-and-pharmacodynamics-of-oral-propranolol-in-pediatric-patients-with-infantile-hemangioma
#18
Tomoki Takechi, Tadao Kumokawa, Rumiko Kato, Takeshi Higuchi, Tsuyoshi Kaneko, Ichiro Ieiri
This study aimed to characterize the population pharmacokinetics and exposure-response relationship of propranolol (Hemangiol® Syrup for Pediatric) in infants with infantile hemangioma. Using nonlinear mixed-effects modeling with 63 pooled sets of plasma concentration-time data from 32 Japanese patients aged 35-150 days, we described the disposition of propranolol adequately by a 1-compartment model with first-order absorption. The estimated population mean apparent clearance and apparent central volume of distribution were 9...
May 10, 2018: Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/29746394/pharmacokinetics-of-doripenem-in-healthy-koreans-and-monte-carlo-simulations-to-explore-optimal-dosage-regimens-in-patients-with-normal-and-enhanced-renal-function
#19
So Won Kim, Sangmin Choe, Dong Jin Kim, Dae Young Zang, Dong-Hwan Lee
BACKGROUND: Dose adjustment is often required in patients with normal or enhanced renal function. The aim of this study is to investigate the pharmacokinetic (PK) properties of doripenem and explore optimal dosing regimens in patients with normal or enhanced renal function according to various minimum inhibitory concentrations (MIC). METHODS: The authors conducted a clinical trial and analyzed PK samples in 11 healthy Korean subjects applying non-compartmental analysis (NCA) and a population approach...
May 9, 2018: Therapeutic Drug Monitoring
https://www.readbyqxmd.com/read/29744900/pharmacokinetics-and-safety-of-fluconazole-and-micafungin-in-neonates-with-systemic-candidiasis-a-randomized-open-label-clinical-trial
#20
S Leroux, E Jacqz Aigrain, V Elie, F Legrand, C Barin-Le Guellec, B Aurich, V Biran, B Dusang, S Goudjil, S Coopman, R Garcia Sanchez, W Zhao, P Manzoni
AIMS: Pharmacokinetics (PK) of fluconazole and micafungin differ in neonates compared with children and adults. Dosing instructions in product labels appear inconsistent with the emerging scientific evidence. Limited information is available on their safety profile in neonates. Our objective was to study population PK and safety of both drugs, randomly administered in neonates with suspected or confirmed systemic candidiasis. METHODS: Neonates were randomized 1:1 to fluconazole (loading dose 25mg/kg; maintenance dose 12 or 20mg/kg/day for infants <30 or ≥ 30 weeks corrected gestational age) or micafungin (loading dose 15mg/kg/day; maintenance dose 10mg/kg/day)...
May 10, 2018: British Journal of Clinical Pharmacology
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