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https://www.readbyqxmd.com/read/28425084/independent-dose-verification-for-brain-stereotactic-radiotherapy-using-different-add-on-micro-multi-leaf-collimators
#1
Shiro Nishiyama, Satoru Ishibashi, Ryo Takahashi, Hidenobu Tachibana
An add-on micro multi-leaf collimator (mMLC) is used for stereotactic radiosurgery (SRS) and brain stereotactic radiotherapy (SRT), in which rotational radiotherapy may make more complex and time-consuming. We performed a retrospective study of an independent dose calculation verification for brain SRS and SRT in two institutions to show the accuracy of the verification system and propose a tolerance value for the verification. Several comparisons of static plans and patients' plans were conducted using a phantom measurement, and patients' plans using the patients' own computed tomography image...
April 19, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28422401/mlc-based-penumbra-softener-of-edw-borders-to-reduce-junction-inhomogeneities
#2
Stanislaw Szpala, Kirpal Kohli
Junctions of fields are known to be susceptible to developing cold or hot spots in the presence of even small geometrical misalignments. Reduction of these dose inhomogeneities can be accomplished through decreasing the dose gradients in the penumbra, but currently it cannot be done for enhanced dynamic wedges (EDW). An MLC-based penumbra softener was developed in the developer mode of TrueBeam linacs to reduce dose gradients across the side border of EDWs. The movement of each leaf was individually synchronized with the movement of the dynamic Y jaw to soften the penumbra in the same manner along the entire field border, in spite of the presence of the dose gradient of the EDW...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28419702/evaluation-of-the-truebeam-machine-performance-check-mpc-mechanical-and-collimation-checks
#3
Michael P Barnes, Peter B Greer
Machine performance check (MPC) is an automated and integrated image-based tool for verification of beam and geometric performance of the TrueBeam linac. The aims of the study were to evaluate the performance of the MPC geometric tests relevant to beam collimation (MLC and jaws) and mechanical systems (gantry and collimator). Evaluation was performed by comparing MPC to QA tests performed routinely in the department over a 4-month period. The MPC MLC tests were compared to an in-house analysis of the Picket Fence test...
April 17, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28407375/h19-promotes-cholestatic-liver-fibrosis-by-preventing-zeb1-mediated-inhibition-of-epcam
#4
Yongfeng Song, Chune Liu, Xia Liu, Jocelyn Trottier, Michele Beaudoin, Li Zhang, Chad Pope, Guangyong Peng, Olivier Barbier, Xiaobo Zhong, Linheng Li, Li Wang
Based on our recent finding that disruption of bile acid (BA) homeostasis in mice results in the induction of hepatic lncRNA H19 expression, we sought to elucidate the role of H19 in cholestatic liver fibrosis. Hepatic overexpression of H19RNA augmented bile duct ligation (BDL)-induced liver fibrosis, which was accompanied by the elevation of serum ALT, AST, bilirubin, and BA levels. Multiple genes related to liver fibrosis, inflammation, and biliary hyperplasia were increased in H19-BDL vs Null-BDL mice, whereas genes in BA synthesis were decreased...
April 13, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/28399367/determination-of-in-vitro-and-in-silico-indexes-for-the-modelling-of-blood-brain-barrier-partitioning-of-drugs-via-micellar-and-immobilized-artificial-membrane-liquid-chromatography
#5
Giacomo Russo, Lucia Grumetto, Roman Szucs, Francesco Barbato, Frederic Lynen
In the present work, 79 structurally unrelated analytes were taken into account and their chromatographic retention coefficients, measured by Immobilized Artificial Membrane Liquid Chromatography (IAM-LC), and by Micellar Liquid Chromatography (MLC) employing sodium dodecyl sulfate (SDS) as surfactant, were determined. Such indexes were subsequently used for the development of Blood-Brain Barrier passage-predictive statistical models using partial least square (PLS) regression along with topological and physico-chemical parameters, calculated in silico...
April 11, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28398517/depolarization-causes-the-formation-of-a-ternary-complex-between-glialcam-mlc1-and-clc-2-in-astrocytes-implications-in-megalencephalic-leukoencephalopathy
#6
Sònia Sirisi, Xabier Elorza-Vidal, Tanit Arnedo, Mercedes Armand-Ugón, Gerard Callejo, Xavier Capdevila-Nortes, Tania López-Hernández, Uwe Schulte, Alejandro Barrallo-Gimeno, Virginia Nunes, Xavier Gasull, Raúl Estévez
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare type of leukodystrophy caused by mutations in either MLC1 or GLIALCAM. GlialCAM is necessary for the correct targeting of MLC1, but also for the targeting of the Cl- channel ClC-2. Furthermore, GlialCAM modifies ClC-2 functional properties in vitro. However, in vivo studies in GlialCAM-/- mice have shown that the modification of ClC-2 activity only occurs in oligodendrocytes, despite GlialCAM and ClC-2 being expressed in astrocytes. Thus, the relationship between GlialCAM, MLC1 and ClC-2 in astrocytes is unknown...
April 7, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28397968/trajectory-optimization-in-radiotherapy-using-sectioning-torus
#7
Christopher Barry Locke, Karl Kenneth Bush
PURPOSE: A challenging problem in trajectory optimization for radiotherapy is properly handling the synchronization of the medical accelerators dynamic delivery. The initial coarse sampling of control points implemented in a Progressive Resolution Optimization type approach (VMAT) routinely results in MLC aperture forming contention issues as the sampling resolution increases. This work presents an approach to optimize continuous, beam-on radiation trajectories through exploration of the anatomical topology present in the patient and formation of a novel dual-metric graph optimization problem...
April 11, 2017: Medical Physics
https://www.readbyqxmd.com/read/28396412/endotoxin-induced-autocrine-atp-signaling-inhibits-neutrophil-chemotaxis-through-enhancing-myosin-light-chain-phosphorylation
#8
Xu Wang, Weiting Qin, Xiaohan Xu, Yuyun Xiong, Yisen Zhang, Huafeng Zhang, Bingwei Sun
Although the neutrophil recruitment cascade during inflammation has been well described, the molecular players that halt neutrophil chemotaxis remain unclear. In this study, we found that lipopolysaccharide (LPS) was a potent stop signal for chemotactic neutrophil migration. Treatment with an antagonist of the ATP receptor (P2X1) in primary human neutrophils or knockout of the P2X1 receptor in neutrophil-like differentiated HL-60 (dHL-60) cells recovered neutrophil chemotaxis. Further observations showed that LPS-induced ATP release through connexin 43 (Cx43) hemichannels was responsible for the activation of the P2X1 receptor and the subsequent calcium influx...
April 10, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28395963/dosimetric-impact-assessment-using-a-general-algorithm-in-geant4-simulations-for-a-complex-shaped-multileaf-collimator
#9
Á Perales, M A Cortés-Giraldo, H Miras, R Arráns, M I Gallardo
PURPOSE: We have developed an inhouse algorithm for the multileaf collimator (MLC) geometry model construction with an appropriate accuracy for dosimetric tests. Our purpose is to build a complex type of MLC and analyze the influence of the modeling parameters on the dose calculation. METHODS: Using radiochromic films as detector the following tests were done: (I) Density test field: to compare measured and calculated dose distributions in order to determine the tungsten alloy physical density value...
April 7, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28391269/rebeccamycin-attenuates-tnf-%C3%AE-induced-intestinal-epithelial-barrier-dysfunction-by-inhibiting-myosin-light-chain-kinase-production
#10
Akihiro Watari, Yuta Sakamoto, Kota Hisaie, Kazuki Iwamoto, Miho Fueta, Kiyohito Yagi, Masuo Kondoh
BACKGROUND/AIMS: Although proinflammatory cytokine-induced disruption of intestinal epithelial barrier integrity is associated with intestinal inflammatory disease, effective treatment for barrier dysfunction is lacking. Previously, we demonstrated that rebeccamycin alleviates epithelial barrier dysfunction induced by inflammatory cytokines in Caco-2 cell monolayers; however, the underlying mechanism remained unclear. Here, we investigated the mechanism by which rebeccamycin protects the epithelial barrier function of Caco-2 cells exposed to TNF-α...
April 7, 2017: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/28387382/non-interferometric-phase-retrieval-using-refractive-index-manipulation
#11
Chyong-Hua Chen, Hsin-Feng Hsu, Hou-Ren Chen, Wen-Feng Hsieh
We present a novel, inexpensive and non-interferometric technique to retrieve phase images by using a liquid crystal phase shifter without including any physically moving parts. First, we derive a new equation of the intensity-phase relation with respect to the change of refractive index, which is similar to the transport of the intensity equation. The equation indicates that this technique is unneeded to consider the variation of magnifications between optical images. For proof of the concept, we use a liquid crystal mixture MLC 2144 to manufacture a phase shifter and to capture the optical images in a rapid succession by electrically tuning the applied voltage of the phase shifter...
April 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28385814/tnf%C3%AE-enhances-force-generation-in-airway-smooth-muscle
#12
Murat Dogan, Young-Soo Han, Philippe F Delmotte, Gary C Sieck
Airway inflammation is a hallmark of asthma triggering airway smooth muscle (ASM) hyperreactivity and airway remodeling. TNFα increases both agonist-induced cytosolic Ca(2+) concentration and force in ASM. The effects of TNFα on ASM force may also be due to an increase in Ca(2+) sensitivity, cytoskeletal remodeling and/or changes in contractile protein content. We hypothesized that 24-h exposure TNFα increases ASM force by changing actin and myosin heavy chain (MyHC) content and/or polymerization. Porcine ASM strips were permeabilized with 10% Triton X-100, and force was measured in response to increasing concentrations of Ca(2+) (pCa 9...
April 6, 2017: American Journal of Physiology. Lung Cellular and Molecular Physiology
https://www.readbyqxmd.com/read/28385495/dosimetric-characterization-of-small-fields-using-a-plastic-scintillator-detector-a-large-multicenter-study
#13
Pietro Mancosu, Massimo Pasquino, Giacomo Reggiori, Laura Masi, Serenella Russo, Michele Stasi
PURPOSE: In modern radiation therapy accurate small fields dosimetry is a challenge and its standardization is fundamental to harmonize delivered dose in different institutions. This study presents a multicenter characterization of MLC-defined small field for Elekta and Varian linear accelerators. Measurements were performed using the Exradin W1 plastic scintillator detector. MATERIALS AND METHODS: The project enrolled 24 Italian centers. Each center performed Tissue Phantom Ratio (TPR), in-plane and cross-plane dose profiles of 0...
April 3, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28384262/dosimetric-effects-of-sectional-adjustments-of-collimator-angles-on-volumetric-modulated-arc-therapy-for-irregularly-shaped-targets
#14
Beom Seok Ahn, So-Yeon Park, Jong Min Park, Chang Heon Choi, Minsoo Chun, Jung-In Kim
PURPOSE: To calculate an optimal collimator angle at each of sectional arcs in a full-arc volumetric modulated arc therapy (VMAT) plan and evaluate dosimetric quality of these VMAT plans comparing full-arc VMAT plans with a fixed collimator angle. METHODS: Seventeen patients who had irregularly-shaped target in abdominal, head and neck, and chest cases were selected retrospectively. To calculate an optimal collimator angle at each of sectional arcs in VMAT, integrated MLC apertures which could cover all shapes of target determined by beam's-eye view (BEV) within angular sections were obtained for each VMAT plan...
2017: PloS One
https://www.readbyqxmd.com/read/28376531/aleukemic-myeloid-leukemia-cutis-with-a-kikuchi-disease-like-inflammatory-pattern-in-myelodysplastic-syndrome
#15
Michelle Khieu, Alexis Beauvais, Rebecca Matz, Adrian Bersabe, Patrick Brown, Alexander Brown, Eric Fillman, Jordan Hall
Myeloid leukemia cutis (MLC) is a rare disease characterized by the infiltration of neoplastic myeloid, myelomonocytic, or monocytic precursors into the skin, producing clinically nonspecific-appearing papules, nodules, plaques, or purpura that necessitate biopsy for definitive diagnosis. In general, it is considered an extramedullary manifestation of acute myeloid leukemia (AML) similar to myeloid sarcoma, also known as a chloroma. MLC often develops in patients with an established diagnosis of AML and is only rarely seen before the onset of systemic disease...
April 2017: Southern Medical Journal
https://www.readbyqxmd.com/read/28370918/effect-of-beam-profile-measurement-on-arc-therapy-plan-quality-assurance-a-case-study
#16
Leonard H Kim, Irina Malajovich, Meral L Reyhan, Jinyu Xue, Joo Han Park
We present an example when profile measurement and modeling of an Elekta Agility multileaf collimator (MLC) had a large effect specifically on arc therapy plan quality assurance (QA) results using ArcCheck. ArcCheck absolute dose measurements of these plans were systematically lower than planned by 3-10%. Failing QA results were seen even with unmodulated static and conformal arcs. Furthermore, the effect was found to be dependent on collimator angle, with worse results associated with near-zero collimator angles...
March 29, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28370002/angular-under-sampling-effect-on-vmat-dose-calculation-an-analysis-and-a-solution-strategy
#17
Ji-Yeon Park, FeiFei Li, Jonathan Li, Darren Kahler, Justin C Park, Guanghua Yan, Chihray Liu, Bo Lu
PURPOSE: Most VMAT algorithms compute the dose on discretized apertures with small angular separations for practical reasons. However, machines deliver the VMAT dose with a continuously moving MLC and gantry and a continuously changing dose rate. The computed dose can deviate from the delivered dose, especially if no, or loose, MLC movement constraints are applied for the VMAT optimization. The goal of this paper is to establish a simplified mathematical model to analyze the discrepancy between the VMAT plan calculation dose and the delivered dose and to provide a reasonable solution for clinical implementation...
April 1, 2017: Medical Physics
https://www.readbyqxmd.com/read/28352215/myosin-iia-related-actomyosin-contractility-mediates-oxidative-stress-induced-neuronal-apoptosis
#18
Yan Wang, Yingqiong Xu, Qian Liu, Yuanyuan Zhang, Zhen Gao, Mingzhu Yin, Nan Jiang, Guosheng Cao, Boyang Yu, Zhengyu Cao, Junping Kou
Oxidative stress-induced neuronal apoptosis plays an important role in the progression of central nervous system (CNS) diseases. In our study, when neuronal cells were exposed to hydrogen peroxide (H2O2), an exogenous oxidant, cell apoptosis was observed with typical morphological changes including membrane blebbing, neurite retraction and cell contraction. The actomyosin system is considered to be responsible for the morphological changes, but how exactly it regulates oxidative stress-induced neuronal apoptosis and the distinctive functions of different myosin II isoforms remain unclear...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28348461/am966-an-antagonist-of-lysophosphatidic-acid-receptor-1-increases-lung-microvascular-endothelial-permeability-through-activation-of-rho-signaling-pathway-and-phosphorylation-of-ve-cadherin
#19
Junting Cai, Jianxin Wei, Shuang Li, Tomeka Suber, Jing Zhao
Maintenance of pulmonary endothelial barrier integrity is important for reducing severity of lung injury. Lysophosphatidic acid (LPA) regulates cell motility, cytoskeletal rearrangement, and cell growth. Knockdown of LPA receptor 1 (LPA1) has been shown to mitigate lung injury and pulmonary fibrosis. AM966, an LPA1 antagonist exhibiting an antifibrotic property, has been considered to be a future antifibrotic medicine. Here, we report an unexpected effect of AM966, which increases lung endothelial barrier permeability...
2017: Mediators of Inflammation
https://www.readbyqxmd.com/read/28339048/agr2-ameliorates-tumor-necrosis-factor-%C3%AE-induced-epithelial-barrier-dysfunction-via-suppression-of-nf-%C3%AE%C2%BAb-p65-mediated-mlck-p-mlc-pathway-activation
#20
Xiaolin Ye, Mei Sun
Intestinal epithelial barrier dysfunction plays a critical role in the pathogenesis of inflammatory bowel disease (IBD). Anterior gradient protein 2 homologue (AGR2) assists in maintaining intestinal homeostasis in dextran sulphate sodium-induced mouse ileocolitis; however, it is unclear whether it modulates intestinal barrier function. Our study aimed to investigate the protective role of AGR2 in tumor necrosis factor (TNF)-α-induced intestinal epithelial barrier injury. Caco-2 cell monolayers were pre-transfected with an AGR2 plasmid and then exposed to TNF-α...
March 21, 2017: International Journal of Molecular Medicine
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