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Jorge Aramburu, Raúl Antón, Alejandro Rivas, Juan Carlos Ramos, Bruno Sangro, José Ignacio Bilbao
Radioembolization, which consist of the implantation of radioactive microspheres via intra-arterially placed microcatheter, is a safe and effective treatment for liver cancer. Nevertheless, radioembolization-related complications and side effects may arise, which are an active area of ongoing research. The catheter design has been claimed as an option in reducing these complications. In this paper, the influence of catheter type and location are investigated. The study was undertaken by numerically simulating the particle-hemodynamics in a patient-specific hepatic artery during liver radioembolization...
October 7, 2016: Journal of Biomechanics
L Tyler Mix, Julia Kirpich, Masato Kumauchi, Jie Ren, Mikas Vengris, Wouter D Hoff, Delmar S Larsen
We explored the photoisomerization mechanisms in novel homologs of Photoactive Yellow Protein (PYP) from Leptospira biflexa to identify conserved features and functional diversity in the primary photochemistry of this family of photoreceptors. In close agreement with the prototypical PYP from Halorhodospira halophila, we observe excited state absorbance near 375 nm and stimulated emission near 500 nm, with triphasic excited state decay. While the excited state decay for Lbif PYP is the slowest among known PYPs due to the redistribution of the amplitudes of the three decay components, the quantum yield for productive photocycle entry is very similar to that of Hhal PYP...
October 17, 2016: Biochemistry
Amy Yuan, Jie Wei, Carl P Gaebler, Hailiang Huang, Devin Olek, Guang Li
PURPOSE: To develop a physical, adaptive motion perturbation model to predict tumor motion using feedback from dynamic measurement of breathing conditions to compensate for breathing irregularities. METHODS AND MATERIALS: A novel respiratory motion perturbation (RMP) model was developed to predict tumor motion variations caused by breathing irregularities. This model contained 2 terms: the initial tumor motion trajectory, measured from 4-dimensional computed tomography (4DCT) images, and motion perturbation, calculated from breathing variations in tidal volume (TV) and breathing pattern (BP)...
September 3, 2016: International Journal of Radiation Oncology, Biology, Physics
Erik Groot Jebbink, Varghese Mathai, Johannes T Boersen, Chao Sun, Cornelis H Slump, Peter C J M Goverde, Michel Versluis, Michel M P J Reijnen
BACKGROUND: Endovascular treatment of aortoiliac occlusive disease entails the use of multiple stents to reconstruct the aortic bifurcation. Different configurations have been applied and geometric variations exist, as quantified in previous work. Other studies concluded that specific stent geometry seems to affect patency. These variations may affect local flow patterns, resulting in different wall shear stress (WSS) and oscillating shear index (OSI). The aim of this study was to compare the effect of different stent configurations on flow perturbations (recirculation and fluid stasis), WSS, and OSI in an in vitro setup...
October 12, 2016: Journal of Vascular Surgery
Martijn L Dijkstra, Peter C J M Goverde, Andrew Holden, Clark J Zeebregts, Michel M P J Reijnen
PURPOSE: To show feasibility of the covered endovascular repair of the aortic bifurcation (CERAB) technique in conjunction with chimney grafts in aortic side branches for complex aortoiliac occlusive disease. METHODS: Two European centers and one facility located in New Zealand participated in a retrospective observational study that enrolled 14 consecutive patients (mean age 61.2±8.9 years; 11 men) treated with CERAB in conjunction with chimney graft(s) between December 2012 and May 2015...
October 14, 2016: Journal of Endovascular Therapy
Jose Negrete, Alain Pumir, Hsin-Fang Hsu, Christian Westendorf, Marco Tarantola, Carsten Beta, Eberhard Bodenschatz
Biological systems with their complex biochemical networks are known to be intrinsically noisy. Here we investigate the dynamics of actin polymerization of amoeboid cells, which are close to the onset of oscillations. We show that the large phenotypic variability in the polymerization dynamics can be accurately captured by a generic nonlinear oscillator model in the presence of noise. We determine the relative role of the noise with a single dimensionless, experimentally accessible parameter, thus providing a quantitative description of the variability in a population of cells...
September 30, 2016: Physical Review Letters
Hannes Schmidt, Stefanie Peters, Katharina Frank, Lai Wen, Robert Feil, Fritz G Rathjen
A cGMP signaling pathway, comprising C-type natriuretic peptide (CNP), its guanylate cyclase receptor Npr2, and cGMP-dependent protein kinase I (cGKI), is critical for the bifurcation of dorsal root ganglion (DRG) and cranial sensory ganglion axons when entering the mouse spinal cord and the hindbrain, respectively. However, the identity and functional relevance of phosphodiesterases (PDEs) that degrade cGMP in DRG neurons are not completely understood. Here we asked whether regulation of the intracellular cGMP concentration by PDEs modulates the branching of sensory axons...
October 14, 2016: European Journal of Neuroscience
A V Sorokin, M Aparicio Alcalde, V M Bastidas, G Engelhardt, D G Angelakis, T Brandes
In this work we study a one-dimensional lattice of Lipkin-Meshkov-Glick models with alternating couplings between nearest-neighbors sites, which resembles the Su-Schrieffer-Heeger model. Typical properties of the underlying models are present in our semiclassical-topological hybrid system, allowing us to investigate an interplay between semiclassical bifurcations at mean-field level and topological phases. Our results show that bifurcations of the energy landscape lead to diverse ordered quantum phases. Furthermore, the study of the quantum fluctuations around the mean-field solution reveals the existence of nontrivial topological phases...
September 2016: Physical Review. E
Irmantas Ratas, Kestutis Pyragas
We analyze the dynamics of a large network of coupled quadratic integrate-and-fire neurons, which represent the canonical model for class I neurons near the spiking threshold. The network is heterogeneous in that it includes both inherently spiking and excitable neurons. The coupling is global via synapses that take into account the finite width of synaptic pulses. Using a recently developed reduction method based on the Lorentzian ansatz, we derive a closed system of equations for the neuron's firing rate and the mean membrane potential, which are exact in the infinite-size limit...
September 2016: Physical Review. E
Liye Zhang, Limin Ying, Jie Zhou, Shuguang Guan, Yong Zou
Evolutionary forces resulted from competitions between different populations are common, which change the evolutionary behavior of a single population. In an isolated population of coordination games of two strategies (e.g., s_{1} and s_{2}), the previous studies focused on determining the fixation probability that the system is occupied by only one strategy (s_{1}) and their expectation times, given an initial mixture of two strategies. In this work, we propose a model of two interdependent populations, disclosing the effects of the interaction strength on fixation probabilities...
September 2016: Physical Review. E
Chol-Ung Choe, Ji-Song Ri, Ryong-Son Kim
We suggest a site disorder model that describes the population of identical oscillators with quenched random interactions for both the coupling strength and coupling phase. We obtain the reduced equations for the suborder parameters, on the basis of Ott-Antonsen ansatz theory, and present a complete bifurcation analysis of the reduced system. New effects include the appearance of the incoherent chimera and glassy state, both of which are caused by heterogeneity of the coupling phases. In the incoherent chimera state, the system displays an exotic symmetry-breaking behavior in spite of the apparent structural symmetry where the oscillators for both of the two subpopulations are in a frustrated state, while the phase distribution for each subpopulation approaches a steady state that differs from each other...
September 2016: Physical Review. E
A B Duncan, S Kalliadasis, G A Pavliotis, M Pradas
We consider the problem of an overdamped Brownian particle moving in multiscale potential with N+1 characteristic length scales: the macroscale and N separated microscales. We show that the coarse-grained dynamics is given by an overdamped Langevin equation with respect to the free energy and with a space-dependent diffusion tensor, the calculation of which requires the solution of N fully coupled Poisson equations. We study in detail the structure of the bifurcation diagram for one-dimensional problems, and we show that the multiscale structure in the potential leads to hysteresis effects and to noise-induced transitions...
September 2016: Physical Review. E
Ludovico La Grutta, Marta Marasà, Patrizia Toia, Daniele Ajello, Domenico Albano, Erica Maffei, Emanuele Grassedonio, Giuseppina Novo, Massimo Galia, Giuseppe Caruso, Salvatore Novo, Filippo Cademartiri, Massimo Midiri
OBJECTIVE: The aim of the study was to compare the atherosclerotic disease in the coronary and carotid arteries in patients who underwent non-invasive imaging for suspected stable coronary artery disease (CAD). MATERIALS AND METHODS: 107 patients (64 men, age 59 ± 12) with atypical chest pain underwent cardiac CT (CCT) and carotid ultrasound (US) on the same day. Severity (obstructive or not-obstructive disease), location, shape, and composition of atherosclerotic plaques in the two districts were evaluated...
October 13, 2016: La Radiologia Medica
Bissacco Daniele, Domanin Maurizio, Del Gobbo Alessandro, Gabrielli Livio
Perigraft seroma is a rare complication occurs after placement of any vascular graft. It is defined as the collection of a sterile, clear and acellular liquid around prosthesis. It can appear years after surgery as a soft, palpable and painless mass. We present a perigraft seroma occurred in a 75-years-patient underwent Dacron right axillo-bifemoral bypass for Leriche's syndrome. Ultrasound and computed tomography scan revealed involvement of graft left branch and bifurcation. Although several treatment options have been proposed, removal and replacement of prosthetic affected tract with another of a different material has been proved the choice with best result...
2016: Annals of Vascular Diseases
Takaaki Saito, Hiroki Tanaka, Naoto Yamamoto, Kazunori Inuzuka, Masaki Sano, Naoki Unno
We report the rare case of a 54-year-old man with uncontrolled renovascular hypertension, who was found to have an abdominal aortic aneurysm with congenital solitary pelvic kidney and superior mesenteric artery stenosis. A single renal artery branched from aneurysmal aortic bifurcation, and both the renal artery and the superior mesenteric artery (SMA) had severe stenosis at their origins. The aneurysm was repaired with a bifurcated Dacron graft, to which the renal artery was anastomosed. SMA bypass was created between the graft's left limb and the SMA using another Dacron graft...
2016: Annals of Vascular Diseases
Meng Zhang, Lijuan Wang, Shi Shu, Aziz Sancar, Dongping Zhong
Photolyase is a blue-light-activated enzyme that repairs ultraviolet-induced DNA damage that occurs in the form of cyclobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone (6-4) photoproducts. Previous studies on microbial photolyases have revealed an electron-tunneling pathway that is critical for the repair mechanism. In this study, we used femtosecond spectroscopy to deconvolute seven electron-transfer reactions in 10 elementary steps in all classes of CPD photolyases. We report a unified electron-transfer pathway through a conserved structural configuration that bifurcates to favor direct tunneling in prokaryotes and a two-step hopping mechanism in eukaryotes...
October 14, 2016: Science
Hussein A Hejase, Kevin J Liu
BACKGROUND: Branching events in phylogenetic trees reflect bifurcating and/or multifurcating speciation and splitting events. In the presence of gene flow, a phylogeny cannot be described by a tree but is instead a directed acyclic graph known as a phylogenetic network. Both phylogenetic trees and networks are typically reconstructed using computational analysis of multi-locus sequence data. The advent of high-throughput sequencing technologies has brought about two main scalability challenges: (1) dataset size in terms of the number of taxa and (2) the evolutionary divergence of the taxa in a study...
October 13, 2016: BMC Bioinformatics
Matthew A Richards, Thomas J Lie, Juan Zhang, Stephen W Ragsdale, John A Leigh, Nathan D Price
: Hydrogenotrophic methanogenesis occurs in multiple environments ranging from the intestinal tracts of animals to anaerobic sediments and hot springs. Energy conservation in hydrogenotrophic methanogens was long a mystery; only within the last decade, it was reported that net energy conservation for growth depends on electron bifurcation. In this work we focus on Methanococcus maripaludis, a well-studied hydrogenotrophic marine methanogen. To better understand hydrogenotrophic methanogenesis and compare it with methylotrophic methanogenesis that utilizes oxidative phosphorylation rather than electron bifurcation, we have built iMR539, a genome scale metabolic reconstruction that accounts for 539 of the 1722 protein-coding genes of M...
October 10, 2016: Journal of Bacteriology
Xianghong Zhang, Sanyi Tang, Robert A Cheke, Huaiping Zhu
Dengue fever has rapidly become the world's most common vector-borne viral disease. Use of endosymbiotic Wolbachia is an innovative technology to prevent vector mosquitoes from reproducing and so break the cycle of dengue transmission. However, strategies such as population eradication and replacement will only succeed if appropriate augmentations with Wolbachia-infected mosquitoes that take account of a variety of factors are carried out. Here, we describe the spread of Wolbachia in mosquito populations using an impulsive differential system with four state variables, incorporating the effects of cytoplasmic incompatibility and the augmentation of Wolbachia-infected mosquitoes with different sex ratios...
October 12, 2016: Bulletin of Mathematical Biology
Chandradhish Ghosh, Mohini Mohan Konai, Paramita Sarkar, Sandip Samaddar, Jayanta Haldar
In the global effort to thwart antimicrobial resistance, lipopeptides are an important class of antimicrobial agents, especially against Gram-negative infections. In an attempt to circumvent their synthetic complexities, we designed simple membrane-active agents involving only one amino acid and two lipid tails. Herein we show that the use of two short lipid tails instead of a single long one significantly increases selective antibacterial activity. This study yielded several selective antibacterial compounds, and investigations into the properties of this compound class were conducted with the most active compound...
October 12, 2016: ChemMedChem
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