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Helical heart

Alexandre Cameron, Alexandros Alexakis
At the heart of today's solar magnetic field evolution models lies the alpha dynamo description. In this work, we investigate the fate of alpha dynamos as the magnetic Reynolds number Rm is increased. Using Floquet theory, we are able to precisely quantify mean-field effects like the alpha and beta effect (i) by rigorously distinguishing dynamo modes that involve large-scale components from the ones that only involve small scales, and by (ii) providing a way to investigate arbitrary large-scale separations with minimal computational cost...
November 11, 2016: Physical Review Letters
Alexander M Matyushenko, Natalia V Artemova, Daniil V Shchepkin, Galina V Kopylova, Salavat R Nabiev, Larisa V Nikitina, Dmitrii I Levitsky, Sergey Y Bershitsky
Tropomyosin (Tpm) is an α-helical coiled-coil actin-binding protein that plays a key role in the Ca(2+)-regulated contraction of striated muscles. Two chains of Tpm can be cross-linked by formation of a disulfide bond between Cys-190 residues. Normally, the SH-groups of these residues in cardiac muscle are in reduced state but in heart pathologies the interchain cross-linking of Tpm was shown to occur. Previous studies have shown that this cross-linking increases the thermal stability of the C-terminal part of the Tpm molecule...
November 14, 2016: Biochemical and Biophysical Research Communications
Jeremy A Sullivan, Ewa Jankowska-Gan, Subramanya Hegde, Matthew A Pestrak, Vrushali V Agashe, Arick C Park, Matthew E Brown, John F Kernien, David S Wilkes, Dixon B Kaufman, Daniel S Greenspan, William J Burlingham
Th17-dependent autoimmune responses can develop after heart or lung transplantation, and are associated with fibro-obliterative forms of chronic rejection. However, the specific self-antigens involved are typically different from those associated with autoimmune disease. To investigate the basis of these responses, we questioned whether removal of Tregs or blockade of function reveals a similar auto-antigen bias. We found that Th17 cells specific for collagen type V (Col V), kα-1-tubulin, and vimentin were present in healthy, adult PBMC, cord blood, and fetal thymus...
November 1, 2016: American Journal of Transplantation
Shuobing Chen, Jiayi Wu, Ying Lu, Yong-Bei Ma, Byung-Hoon Lee, Zhou Yu, Qi Ouyang, Daniel J Finley, Marc W Kirschner, Youdong Mao
The proteasome is the major engine of protein degradation in all eukaryotic cells. At the heart of this machine is a heterohexameric ring of AAA (ATPases associated with diverse cellular activities) proteins that unfolds ubiquitylated target proteins that are concurrently translocated into a proteolytic chamber and degraded into peptides. Using cryoelectron microscopy, we determined a near-atomic-resolution structure of the 2.5-MDa human proteasome in its ground state, as well as subnanometer-resolution structures of the holoenzyme in three alternative conformational states...
November 15, 2016: Proceedings of the National Academy of Sciences of the United States of America
Clive J Curley, Eimear B Dolan, Brenton Cavanagh, Janice O'Sullivan, Garry P Duffy, Bruce P Murphy
Localized delivery of stem cells is potentially a promising therapeutic strategy for regenerating damaged myocardium. Many studies focus on limiting the biologic component of cell loss, but few address the contribution of mechanical factors. This study investigates optimal parameters for retaining the largest volume of cell loaded hydrogels post intramyocardial injection, without compromising cell viability. In vitro, hydrogel was injected into porcine hearts using various needle designs. Hydrogel retention and distribution pattern was then determined...
October 20, 2016: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
Daniel A Hernandez, Christina M Bennett, Lyubov Dunina-Barkovskaya, Tatjana Wedig, Yassemi Capetanaki, Harald Herrmann, Gloria M Conover
In the hearts of patients bearing nebulette mutations, a severe general disorganization in cardiomyocytes of the extrasarcomeric desmin intermediate filament system is frequently observed. However, the molecular and functional relationship between the desmin cytoskeleton and nebulette-containing sarcomeres is still unclear. Here we report a high-affinity in vitro interaction between nebulette and desmin filaments. A major interaction site has been mapped to the desmin α-helical rod domain, indicating that the filament core is directly involved in the binding of nebulette...
December 1, 2016: Molecular Biology of the Cell
Wei Peng, Huaizong Shen, Jianping Wu, Wenting Guo, Xiaojing Pan, Ruiwu Wang, S R Wayne Chen, Nieng Yan
RyR2 is a high-conductance intracellular calcium (Ca(2+)) channel that controls the release of Ca(2+) from the sarco(endo)plasmic reticulum of a variety of cells. Here, we report the structures of RyR2 from porcine heart in both the open and closed states at near-atomic resolutions determined using single-particle electron cryomicroscopy. Structural comparison reveals a breathing motion of the overall cytoplasmic region resulted from the interdomain movements of amino-terminal domains (NTDs), Helical domains, and Handle domains, whereas almost no intradomain shifts are observed in these armadillo repeats-containing domains...
October 21, 2016: Science
Ilma Xhaferllari, Omar El-Sherif, Stewart Gaede
Volumetric-modulated arc therapy (VMAT) is emerging as a leading technology in treating early-stage, non-small cell lung cancer (NSCLC) with stereotactic ablative radiotherapy (SABR). However, two other modalities capable of deliver-ing intensity-modulated radiation therapy (IMRT) include fixed-beam and helical TomoTherapy (HT). This study aims to provide an extensive dosimetric compari-son among these various IMRT techniques for treating early-stage NSCLC with SABR. Ten early-stage NSCLC patients were retrospectively optimized using three fixed-beam techniques via nine to eleven beams (high and low modulation step-and-shoot (SS), and sliding window (SW)), two VMAT techniques via two partial arcs (SmartArc (SA) and RapidArc (RA)), and three HT techniques via three different fan beam widths (1 cm, 2...
2016: Journal of Applied Clinical Medical Physics
Olivier Lauche, Youlia M Kirova, Pascal Fenoglietto, Emilie Costa, Claire Lemanski, Celine Bourgier, Olivier Riou, David Tiberi, Francois Campana, Alain Fourquet, David Azria
AIM: To analyse clinical and dosimetric results of helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) in complex adjuvant breast and nodes irradiation. METHODS: Seventy-three patients were included (31 HT and 42 VMAT). Dose were 63.8 Gy (HT) and 63.2 Gy (VMAT) in the tumour bed, 52.2 Gy in the breast, 50.4 Gy in supraclavicular nodes (SCN) and internal mammary chain (IMC) with HT and 52.2 Gy and 49.3 Gy in IMC and SCN with VMAT in 29 fractions...
August 28, 2016: World Journal of Radiology
Carrie E Herbert, Surendranath Veeram Reddy, Tré R Welch, Jian Wang, James A Richardson, Joseph M Forbess, Alan W Nugent
BACKGROUND: Metallic endovascular stents are utilized off-label in congenital heart disease. Biodegradable stents (BDS) offer potential advantages in a growing child. We have previously reported double opposed helical (DH) BDS up to 6 mm diameter (DH-6). The objectives are to investigate the bench characteristics of larger 8 mm diameter BDS (DH-8) manufactured with increasing strut thicknesses and the inflammatory profile in a porcine model. METHODS: DH-8 were manufactured with strut thicknesses 0...
July 29, 2016: Catheterization and Cardiovascular Interventions
Yang Mei, Karen Glover, Minfei Su, Sangita C Sinha
BECN1 (Beclin 1), a highly conserved eukaryotic protein, is a key regulator of autophagy, a cellular homeostasis pathway, and also participates in vacuolar protein sorting, endocytic trafficking, and apoptosis. BECN1 is important for embryonic development, the innate immune response, tumor suppression, and protection against neurodegenerative disorders, diabetes, and heart disease. BECN1 mediates autophagy as a core component of the class III phosphatidylinositol 3-kinase complexes. However, the exact mechanism by which it regulates the activity of these complexes, or mediates its other diverse functions is unclear...
October 2016: Protein Science: a Publication of the Protein Society
Wenjun Zheng, Sarah E Hitchcock-DeGregori, Bipasha Barua
Tropomyosin (Tpm) is a two-chained α-helical coiled-coil protein that binds to filamentous actin (F-actin), and regulates its interactions with myosin by occupying three average positions on F-actin (blocked, closed, and open). Mutations in the Tpm are linked to heart diseases including hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). To elucidate the molecular mechanisms of Tpm mutations (including DCM mutation E54K, HCM mutations E62Q, A63V, K70T, V95A, D175N, E180G, L185R, E192K, and a designed synthetic mutation D137L) in terms of their effects on Tpm flexibility and its interactions with F-actin, we conducted extensive molecular dynamics simulations for the wild-type and mutant Tpm in complex with F-actin (total simulation time 160 ns per mutant)...
July 4, 2016: Journal of Muscle Research and Cell Motility
Adrian Nalichowski, Don G Eagle, Jay Burmeister
This study compared 2 different treatment planning systems (TPSs) for quality and efficiency of total marrow irradiation (TMI) plans. The TPSs used in this study were VOxel-Less Optimization (VoLO) (Accuray Inc, Sunnyvale, CA) using helical dose delivery on a Tomotherapy Hi-Art treatment unit and Eclipse (Varian Medical Systems Inc, Palo Alto, CA) using volumetric modulated arc therapy (VMAT) dose delivery on a Varian iX treatment unit. A total dose of 1200cGy was prescribed to cover 95% of the planning target volume (PTV)...
2016: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
Emel Haciislamoglu, Fatma Colak, Emine Canyilmaz, Ahmet Yasar Zengin, Ahmet Hakan Yilmaz, Adnan Yoney, Zumrut Bahat
The aim of this study was to identify a rational strategy for the selection of multi-beam IMRT in patients with right breast cancer through the comparison of dosimetric parameters of the planning target volume (PTV) and organs at risk (OARs) using five different radiotherapy modalities. This was a retrospective study using computed tomography scans from ten patients with early-stage right breast cancer who had been treated previously. Three dimensional conformal radiotherapy (3DCRT), forward-planned IMRT (for-IMRT), inverse-planned IMRT (inv-IMRT), helical tomotherapy (HT), and volumetric-modulated arc therapy (VMAT) were planned for each patient...
2016: SpringerPlus
Vanessa Cabra, Takashi Murayama, Montserrat Samsó
In heart, type-2 ryanodine receptor (RyR2) forms discrete supramolecular clusters in the sarcoplasmic reticulum known as calcium release units (CRUs), which are responsible for most of the Ca(2+) released for muscle contraction. To learn about the substructure of the CRU, we sought to determine whether RyR2s have the ability to self-associate in the absence of other factors and if so, whether they do it in a specific manner. Purified RyR2 was negatively stained and imaged on the transmission electron microscope, and RyR2 particles closely associated were further analyzed using bias-free multivariate statistical analysis and classification...
June 21, 2016: Biophysical Journal
Yueh-Feng Lu, Yu-Chin Lin, Kuo-Hsin Chen, Pei-Wei Shueng, Hsin-Pei Yeh, Chen-Hsi Hsieh
Treatment for bilateral breast cancer with chest wall and abdominal skin invasion normally involves conventional radiotherapy (RT); however, conventional RT provides inadequate target volume coverage and excessive treatment of large volumes of normal tissue. Helical tomotherapy (HT) has the ability to deliver continuous craniocaudal irradiation that suppresses junction problems and provides good conformity of dose distribution. A 47-year-old female with stage IV bilateral breast cancer with chest wall and pectoralis major muscle invasion, lymphadenopathy, bilateral pleural effusion, and multiple bone metastases received chemotherapy and target therapy beginning in January 2014; 4 months after the initiation of chemotherapy, computed tomography revealed progression of chest and abdominal wall invasion...
2016: OncoTargets and Therapy
Orit Kaidar-Person, Mark Kostich, Timothy M Zagar, Ellen Jones, Gaorav Gupta, Panayiotis Mavroidis, Shiva K Das, Lawrence B Marks
UNLABELLED: We report our initial clinical experience with using Helical tomotherapy to irradiate the bilateral breasts/chest-wall and regional nodes. METHODS: The records of patients who received bilateral irradiation of the breast/chest-wall and regional nodes with tomotherapy were retrospectively reviewed. Clinical outcomes for tumor and normal tissues were assessed. RESULTS: From August 2011 to January 2016, nine women were identified; median age 52 years (range 37-74), mean follow up was 10...
August 2016: Breast: Official Journal of the European Society of Mastology
Francesca M Giugliano, Vincenzo Iorio, Fabrizio Cammarota, Diego Toledo, Rossana Senese, Ferdinando Francomacaro, Matteo Muto, Paolo Muto
Patients who have undergone solid organ transplants are known to have an increased risk of neoplasia compared with the general population. We report our experience using mediastinal irradiation with helical tomotherapy versus three-dimensional conformal radiation therapy to treat a patient with lung carcinoma 15 years after heart transplantation. Our dosimetric evaluation showed no particular difference between the techniques, with the exception of some organs. Mediastinal irradiation after heart transplantation is feasible and should be considered after evaluation of the risk...
April 26, 2016: Thoracic Cancer
Omar El-Sherif, Edward Yu, Ilma Xhaferllari, Stewart Gaede
PURPOSE: To use 4-dimensional computed tomography (4D-CT) imaging to predict the level of uncertainty in cardiac dose estimates of the left anterior descending artery that arises due to breathing motion during radiation therapy for left-sided breast cancer. METHODS AND MATERIALS: The fast helical CT (FH-CT) and 4D-CT of 30 left-sided breast cancer patients were retrospectively analyzed. Treatment plans were created on the FH-CT. The original treatment plan was then superimposed onto all 10 phases of the 4D-CT to quantify the dosimetric impact of respiratory motion through 4D dose accumulation (4D-dose)...
July 1, 2016: International Journal of Radiation Oncology, Biology, Physics
Ali Jazayeri, Andrew S Doré, Daniel Lamb, Harini Krishnamurthy, Stacey M Southall, Asma H Baig, Andrea Bortolato, Markus Koglin, Nathan J Robertson, James C Errey, Stephen P Andrews, Iryna Teobald, Alastair J H Brown, Robert M Cooke, Malcolm Weir, Fiona H Marshall
Glucagon is a 29-amino-acid peptide released from the α-cells of the islet of Langerhans, which has a key role in glucose homeostasis. Glucagon action is transduced by the class B G-protein-coupled glucagon receptor (GCGR), which is located on liver, kidney, intestinal smooth muscle, brain, adipose tissue, heart and pancreas cells, and this receptor has been considered an important drug target in the treatment of diabetes. Administration of recently identified small-molecule GCGR antagonists in patients with type 2 diabetes results in a substantial reduction of fasting and postprandial glucose concentrations...
April 25, 2016: Nature
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