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81.
Tanya Kairn Marika Lathouras Michelle Grogan Benjamin Green Steven R. Sylvander Scott B. Crowe 《Medical Dosimetry》2021,46(1):13-20
Gas-filled temporary tissue expanders (TTEs), implanted to assist in post mastectomy breast reconstructions, are expected to produce increased dosimetric uncertainty in breast radiotherapy treatments, due to their containing both a substantial metallic component and a comparatively large volume of gas. This study therefore builds on previous investigations of the dosimetric effects of gas-filled TTEs in static photon and electron beams, by examining the effects of these implants on dose distributions from common modulated rotational treatment techniques; volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT). Radiochromic film measurements were used to evaluate the accuracy of VMAT and HT dose calculations, for a humanoid phantom augmented with a sample Aeroform CO2-filled TTE (AirXpanders Inc, San Jose, USA) as well as purpose-designed and 3D printed “breast tissue.” Results showed that the TomoTherapy Hi-Art VoLO convolution-superposition algorithm (Accuray Inc, Sunnyvale, USA) produced comparatively accurate calculations of treatment dose within this complex phantom, including immediately anterior and posterior to the TTE. The Varian Eclipse Acuros (AXB) algorithm generally showed better agreement with the film measurement than the Varian Eclipse AAA algorithm (Varian Medical Systems, Palo Alto, USA), although the film measurements showed regions of 5% to 10% disagreement with both AAA and AXB in the dosimetrically-challenging region on the anterior side of the implant. Although the Aeroform CO2-filled TTE has substantial and obvious effects on the downstream dose from a static photon beam, the results of this study showed how inverse-planning of modulated rotational radiotherapy treatments can produce modulated fluence distributions that compensate for the dramatic density heterogeneities in the implant. Despite some disagreements with the planned dose, all film measurements showed that the use of inverse-planned modulated rotational photon beams resulted in comparatively homogeneous coverage of the radiotherapy target, in the complex patient-like phantom with a gas-filled TTE. Due to the importance of matching each planned fluence distribution to the density distribution within each TTE, careful use of available 3D imaging techniques is advisable, when modulated rotational radiotherapy treatments are delivered to patients with gas-filled TTEs. 相似文献
82.
Tanya L. Brown Hirokazu Hashimoto Lisbet T. Finseth Teresa L. Wood Wendy B. Macklin 《The Journal of neuroscience》2021,41(9):1864
The actin cytoskeleton is crucial for oligodendrocyte differentiation and myelination. Here we show that p21-activated kinase 1 (PAK1), a well-known actin regulator, promotes oligodendrocyte morphologic change and myelin production in the CNS. A combination of in vitro and in vivo models demonstrated that PAK1 is expressed throughout the oligodendrocyte lineage with highest expression in differentiated oligodendrocytes. Inhibiting PAK1 early in oligodendrocyte development decreased oligodendrocyte morphologic complexity and altered F-actin spreading at the tips of oligodendrocyte progenitor cell processes. Constitutively activating AKT in oligodendrocytes in male and female mice, which leads to excessive myelin wrapping, increased PAK1 expression, suggesting an impact of PAK1 during active myelin wrapping. Furthermore, constitutively activating PAK1 in oligodendrocytes in zebrafish led to an increase in myelin internode length while inhibiting PAK1 during active myelination decreased internode length. As myelin parameters influence conduction velocity, these data suggest that PAK1 may influence communication within the CNS. These data support a model in which PAK1 is a positive regulator of CNS myelination.SIGNIFICANCE STATEMENT Myelin is a critical component of the CNS that provides metabolic support to neurons and also facilitates communication between cells in the CNS. Recent data demonstrate that actin dynamics drives myelin wrapping, but how actin is regulated during myelin wrapping is unknown. The authors investigate the role of the cytoskeletal modulator PAK1 during differentiation and myelination by oligodendrocytes, the myelinating cells of the CNS. They demonstrate that PAK1 promotes oligodendrocyte differentiation and myelination by modulating the cytoskeleton and thereby internode length, thus playing a critical role in the function of the CNS. 相似文献
83.
Connie Marras MD PhD Kelly A. Mills MD Shirley Eberly MS David Oakes PhD Kelvin L. Chou MD PhD Matthew Halverson BA BS Sotirios A. Parashos MD PhD Christopher G. Tarolli MD MHPE Jin-Shei Lai PhD Cindy J. Nowinsky MD PhD Oksana Suchowersky MD Eric S. Farbman MD Lisa M. Shulman MD Tanya Simuni MD 《Movement disorders》2021,36(8):1979-1983
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Turjeman Adi Babich Tanya Pujol Miquel Carratalà Jordi Shaw Evelyn Gomila-Grange Aina Vuong Cuong Addy Ibironke Wiegand Irith Grier Sally MacGowan Alasdair Vank Christiane Cuperus Nienke van den Heuvel Leo Leibovici Leonard Eliakim-Raz Noa 《European journal of clinical microbiology & infectious diseases》2021,40(9):2005-2010
European Journal of Clinical Microbiology & Infectious Diseases - Complicated urinary tract infection (cUTI) is a frequent cause of morbidity. In this multinational retrospective cohort study,... 相似文献
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Reproducibility of MR‐based liver fat quantification across field strength: Same‐day comparison between 1.5T and 3T in obese subjects
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Annette Estes Lonnie Zwaigenbaum Hongbin Gu Tanya St. John Sarah Paterson Jed T. Elison Heather Hazlett Kelly Botteron Stephen R. Dager Robert T. Schultz Penelope Kostopoulos Alan Evans Geraldine Dawson Jordana Eliason Shanna Alvarez Joseph Piven IBIS network 《Journal of Neurodevelopmental Disorders》2015,7(1)