Read by QxMD icon Read


Floriane Boullot, Justine Castrec, Adeline Bidault, Natanael Dantas, Laura Payton, Mickael Perrigault, Damien Tran, Zouher Amzil, Pierre Boudry, Philippe Soudant, Hélène Hégaret, Caroline Fabioux
Paralytic shellfish toxins (PST) bind to voltage-gated sodium channels (Nav) and block conduction of action potential in excitable cells. This study aimed to (i) characterize Nav sequences in Crassostrea gigas and (ii) investigate a putative relation between Nav and PST-bioaccumulation in oysters. The phylogenetic analysis highlighted two types of Nav in C. gigas: a Nav1 (CgNav1) and a Nav2 (CgNav2) with sequence properties of sodium-selective and sodium/calcium-selective channels, respectively. Three alternative splice transcripts of CgNav1 named A, B and C, were characterized...
January 19, 2017: Marine Drugs
Kathi A Lefebvre, Lori Quakenbush, Elizabeth Frame, Kathy Burek Huntington, Gay Sheffield, Raphaela Stimmelmayr, Anna Bryan, Preston Kendrick, Heather Ziel, Tracey Goldstein, Jonathan A Snyder, Tom Gelatt, Frances Gulland, Bobette Dickerson, Verena Gill
Current climate trends resulting in rapid declines in sea ice and increasing water temperatures are likely to expand the northern geographic range and duration of favorable conditions for harmful algal blooms (HABs), making algal toxins a growing concern in Alaskan marine food webs. Two of the most common HAB toxins along the west coast of North America are the neurotoxins domoic acid (DA) and saxitoxin (STX). Over the last 20 years, DA toxicosis has caused significant illness and mortality in marine mammals along the west coast of the USA, but has not been reported to impact marine mammals foraging in Alaskan waters...
May 2016: Harmful Algae
Kieng Soon Hii, Po Teen Lim, Nyuk Fong Kon, Yoshinobu Takata, Gires Usup, Chui Pin Leaw
Saxitoxins (STXs) constitute a family of potent sodium channel blocking toxins, causative agents of paralytic shellfish poisoning (PSP), and are produced by several species of marine dinoflagellates and cyanobacteria. Two STX-core genes, sxtA and sxtG, have been well elucidated in Alexandrium but the expression of these genes under various nutritional modes in tropical species remains unclear. This study investigates the physiological responses of a tropical Pacific strain of Alexandrium minutum growing with nitrate or ammonium, and with various nitrogen to phosphorus (N:P) supply ratios...
June 2016: Harmful Algae
Débora Monteiro Brentano, Eduardo L Hettwer Giehl, Maurício Mello Petrucio
The cyanobacterium Cylindrospermopsis raciborskii is capable of producing toxins including saxitoxin (STX). Few studies have verified the influence of environmental variables on the production of STX and most have only been studied in the laboratory. The goal of this work was to identify the abiotic variables related to STX concentration in situ. The relationship among STX concentration and the physical variables, nutrients and chlorophyll-a (chl-a) concentration was examined in a meso-oligotrophic subtropical coastal lake dominated by C...
June 2016: Harmful Algae
Henna Savela, Kirsi Harju, Lisa Spoof, Elin Lindehoff, Jussi Meriluoto, Markus Vehniäinen, Anke Kremp
Many marine dinoflagellates, including several species of the genus Alexandrium, Gymnodinium catenatum, and Pyrodinium bahamense are known for their capability to produce paralytic shellfish toxins (PST), which can cause severe, most often food-related poisoning. The recent discovery of the first PST biosynthesis genes has laid the foundation for the development of molecular detection methods for monitoring and study of PST-producing dinoflagellates. In this study, a probe-based qPCR method for the detection and quantification of the sxtA4 gene present in Alexandrium spp...
February 2016: Harmful Algae
Lisa K Eckford-Soper, Eileen Bresnan, Jean-Pierre Lacaze, David H Green, Keith Davidson
The dinoflagellate Alexandrium produces paralytic shellfish poisoning toxins. The genus is globally distributed, with Scottish waters being of particular interest due to the co-occurrence of different species and strains. In Scottish waters, Alexandrium was historically thought to be dominated by the highly toxic (Group I) Alexandrium fundyense. However, the morphologically indistinguishable (Group III) Alexandrium tamarense has recently also been found to co-occur, raising important questions in relation to Alexandrium biogeography...
March 2016: Harmful Algae
Pardis Saeedi, Maryam Yazdanparast, Elham Behzadi, Ali Hatef Salmanian, Seyed Latif Mousavi, Shahram Nazarian, Jafar Amani
Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is a food-borne pathogen that younger children are most prone to this microorganism. Hemolytic Uremic Syndrome (HUS) caused by EHEC, leads to the destruction of red blood cells and kidney failure. The virulence of E.coli O157:H7 is attributed to fimbriae, that facilitate colonization of bacteria within the colon and verotoxins (VT) or Shiga toxins (Stx) that are released into the blood. Although, in most cases, the infection is self-limitedin young children and aged population, it may cause HUS...
January 3, 2017: Microbial Pathogenesis
I Brezovich, X Wu, R Popple, S Shen, R Cardan, M Bolding, J Fiveash, J Kraus, S Spencer
PURPOSE: To test spatial and dosimetric accuracy of small cranial target irradiation based on 1.5 T MRI scans using static arcs with MLC-defined fields METHODS: A plastic (PMMA) phantom simulating a small brain lesion was mounted on a GammaKnife headframe equipped with MRI localizer. The lesion was a 3 mm long, 3.175 mm diameter cylindrical cavity filled with MRI contrast. Radiochromic film passing through the cavity was marked with pin pricks at the cavity center. The cavity was contoured on an MRI image and fused with CT to simulate treatment of a lesion not visible on CT...
June 2016: Medical Physics
V Mhatre, P Patwe, P Dandekar
PURPOSE: Quality assurance (QA) of complex linear accelerators is critical and highly time consuming. ArcCHECK Machine QA tool is used to test geometric and delivery aspects of linear accelerator. In this study we evaluated the performance of this tool. METHODS: Machine QA feature allows user to perform quality assurance tests using ArcCHECK phantom. Following tests were performed 1) Gantry Speed 2) Gantry Rotation 3) Gantry Angle 4)MLC/Collimator QA 5)Beam Profile Flatness & Symmetry...
June 2016: Medical Physics
W Campbell, M Miften, T Schefter, K Goodman, B Jones
PURPOSE: Pancreatic SBRT is uniquely challenging due to both the erratic/unstable motion of the pancreas and the close proximity of the radiosensitive small bowel. Respiratory gating can mitigate this effect, but the irregularity of motion severely affects traditional phase-based gating. The purpose of this study was to analyze real-time motion data of pancreatic tumors to optimize the efficacy and accuracy of respiratory gating, with the overall goal of enabling dose escalated pancreatic SBRT...
June 2016: Medical Physics
Y Choi, J Kwak, C Jeong, S Ahn, S Lee, B Cho
PURPOSE: To compare the commissioned beam data for one flattening filter photon mode (6 MV) and two flattening filter-free (FFF) photon modes (6 and 10 MV-FFF) between Trilogy Tx and TrueBeam STx and evaluate the possibility of dosimetric matching METHODS: Dosimetric characteristics of the new Trilogy Tx including percent depth doses (PDDs), profiles, and output factors were measured for commissioning. Linear diode array detector and ion chambers were used to measure dosimetric data. The depth of dose maximum (dmax) and PDD at 10 cm (PDD10) were evaluated: 3×3 cm(2) , 10×10 cm(2) , and 40×40 cm(2) ...
June 2016: Medical Physics
G Cui, N Trakul, E Chang, A Shiu
PURPOSE: To evaluate the reproducibility of target position using moderate voluntary breath-hold during liver stereotactic ablative radiotherapy (SABR). METHODS: Two patients who underwent liver SABR on a Varian TrueBeam STx linac were used for this study. Fiducial markers were placed in and around the target in the liver as surrogates for the target position and motion. GTVs were contoured by assessing tumor extent on contrast enhanced CT. The PTV was created from the GTV by adding 2 mm margins to account for the residual motion during breath-holds...
June 2016: Medical Physics
E Goksel, H Kucucuk, O Senkesen, E Tezcanli
PURPOSE: Different placements of Infrared Cameras (IRC) in CT and treatment rooms can cause gating window level (GWL) variations leading to differences between GWL used for planning and treatments. Although, Varian Clinac DHX-OBI sytem and CT are equipped with the same kind of IRC, Truebeam STx (TB) has a different type of IRC known as banana type. In this study; geometric and dosimetric accuracy of respiratory management system (RPM) for different machines were investigated with a special homemade phantom...
June 2016: Medical Physics
J Li, W Shi, D Andrews, M Werner-Wasik, B Lu, Y Yu, A Dicker, H Liu
PURPOSE: To compare online image registrations of TrueBeam cone-beam CT (CBCT) and BrainLab ExacTrac x-ray imaging systems for cranial radiotherapy. METHOD: Phantom and patient studies were performed on a Varian TrueBeam STx linear accelerator (Version 2.5), which is integrated with a BrainLab ExacTrac imaging system (Version 6.1.1). The phantom study was based on a Rando head phantom, which was designed to evaluate isocenter-location dependence of the image registrations...
June 2016: Medical Physics
P Patwe, V Mhatre, P Dandekar
PURPOSE: Indigenous Farmer type chamber FAR 65 GB is a reference class 0.6 cc ion chamber. It can be used for dosimetric evaluation of photon and high energy electron beams. We studied dosimetric characteristics of the chamber for 6MV and 10MV Flattening filter free FFF photon beams available on trueBEAM STx Linac. METHODS: The study was carried out on trueBEAM STx Linac having 6 and 10 MV FFF photon beam with maximum dose rate 1400 and 2400 MU per min respectively...
June 2016: Medical Physics
S Jang, M Hwang, D Michalski, R Lalonde, M Huq
PURPOSE: To evaluate possible inter-fractional tumor motion variability for pancreatic SBRT with length measurement of the fiducial depiction on the scan and to develop an empirical correlation using a moving phantom and fiducials for adjusting gating window on a daily basis METHODS: In this retrospective study, motion data for fifty pancreatic SBRT patients with fiducials were selected to find the tumor motion statistics. Three gold fiducials of 5mm were placed around a solid target inside the Quasar Phantom and the 4D CT images of the Phantom were acquired with tumor motion of 1cm in superior-inferior direction...
June 2016: Medical Physics
D Desai, G Narayanasamy, S Senthamizhchelvan, H Elasmar, R Zwicker, E Johnson
PURPOSE: SBRT of lung tumor results in steep dose fall-off outside the PTV to limit the normal tissue dose. RTOG report 0915 recommended metrics for plan quality measure, CI, D2cm, R50% and HDloc were evaluated. This study was aimed at ascertaining moderate to low dose spillage using 5 mm ring structures outside the PTV. METHODS: In this retrospective study, 41 clinical RapidArc lung SBRT plans (Eclipse TPS ver 8.9) previously treated at our institution in a TrueBeam STx linac were analyzed...
June 2016: Medical Physics
S Lim, L Kuo, L Happersett, D Lovelock, A Ballangrud, T LoSasso
PURPOSE: To commission a custom 6MV-SRS-AAA Eclipse beam model for VMAT multiple lesions cranial SRS treatment on a Varian TrueBeam STx. METHODS: Six clinical plans were created using a customized beam model with dosimetric-leaf-gap(DLG) optimized for clinical treatments. Each plan had 4-6 non-isocentric targets with size from 0.2 to 7.1cc. All fields were measured with EBT3 film in the coronal plane in a solid water phantom and with an AS1000 EPID using gantry rotation...
June 2016: Medical Physics
B Wilson, E Gete
PURPOSE: This work investigates the dosimetric accuracy of a trajectory based delivery technique in which an optimized radiation beam is delivered along a Couch-Gantry trajectory that is formed by simultaneous rotation of the linac gantry and the treatment couch. METHODS: Nine trajectory based cranial SRS treatment plans were created using in-house optimization software. The plans were calculated for delivery on the TrueBeam STx linac with 6MV photon beam. Dose optimization was performed along a user-defined trajectory using MLC modulation, dose rate modulation and jaw tracking...
June 2016: Medical Physics
V Mhatre, P Patwe, P Dandekar
PURPOSE: Optical Surface Monitoring system (OSMS) have been recently introduced by Varian for initial patient positioning and real-time monitoring during complex radiotherapy treatment. The purpose of this work was to implement TG 147 with OSMS. METHODS: Recently we installed OSMS first of its kind in India on trueBEAM STx at our Institue. The OSMS is composed of a three cameras ceiling mounted and a Workstation. The following tests were performed to validate the system a...
June 2016: Medical Physics
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"