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Pulse sequence

Brandon M Wild, Renée Morris, Mihai Moldovan, Christian Krarup, Arun V Krishnan, Ria Arnold
Electrophysiology enables the objective assessment of peripheral nerve function in vivo. Traditional nerve conduction measures such as amplitude and latency detect chronic axon loss and demyelination, respectively. Axonal excitability techniques "by threshold tracking" expand upon these measures by providing information regarding the activity of ion channels, pumps and exchangers that relate to acute function and may precede degenerative events. As such, the use of axonal excitability in animal models of neurological disorders may provide a useful in vivo measure to assess novel therapeutic interventions...
February 6, 2018: Journal of Visualized Experiments: JoVE
Xing Wang, Guang-Ming Zhang, Hongwei Ma, Yishu Zhang, Doudou Wang
In ultrasonic array imaging, 3D ultrasonic wavefields are normally recorded by an ultrasonic piezo array transducer. Its performance is limited by the configuration and size of the array transducer. In this paper, a method based on digital holographic interferometry is proposed to record the 3D ultrasonic wavefields instead of the array transducer, and the measurement system consisting of a pulsed laser, ultrasonic excitation, and synchronization and control circuit is designed. A consecutive sequence of holograms of ultrasonic wavefields are recorded by the system...
February 13, 2018: Sensors
Asier Marzo, Mihai Caleap, Bruce W Drinkwater
Acoustic vortices can transfer angular momentum and trap particles. Here, we show that particles trapped in airborne acoustic vortices orbit at high speeds, leading to dynamic instability and ejection. We demonstrate stable trapping inside acoustic vortices by generating sequences of short-pulsed vortices of equal helicity but opposite chirality. This produces a "virtual vortex" with an orbital angular momentum that can be tuned independently of the trapping force. We use this method to adjust the rotational speed of particles inside a vortex beam and, for the first time, create three-dimensional acoustics traps for particles of wavelength order (i...
January 26, 2018: Physical Review Letters
Vanesa García, Inácio Mandomando, Joaquim Ruiz, Silvia Herrera-León, Pedro L Alonso, M Rosario Rodicio
Background and purpose: Invasive nontyphoidal salmonellosis, mostly caused by serovars Typhimurium and Enteritidis of Salmonella enterica, has emerged as a major public health problem in sub-Saharan Africa. The aim of this study was the clinical and microbiological characterization of nontyphoidal salmonellosis episodes affecting febrile children in Mozambique. Patients and methods: The clinical records of the patients were evaluated, and S. enterica isolates were characterized with regard to serovar, phage type, antimicrobial resistance (phenotype/responsible genes), plasmid content, pulsed-field gel electrophoresis, and multilocus sequence typing...
2018: Infection and Drug Resistance
Andre Bongers, Eric Hau, Han Shen
PURPOSE: To investigate a novel alternative diffusion-weighted imaging (DWI) approach using oscillating gradients preparation (OGSE) to obtain much shorter effective diffusion times (Δ eff ) for tumor response monitoring by apparent diffusion coefficient (ADC) mapping in a glioblastoma mouse model. METHODS AND MATERIALS: Twenty-four BALB/c nude mice inoculated with U87 glioblastoma cells were randomized into a control group and an irradiation group, which underwent a 15-day fractioned radiation therapy (RT) course with 2 Gy/d...
January 4, 2018: International Journal of Radiation Oncology, Biology, Physics
Tzitziki Loeza-Quintana, Sarah J Adamowicz
During the past 50 years, the molecular clock has become one of the main tools for providing a time scale for the history of life. In the era of robust molecular evolutionary analysis, clock calibration is still one of the most basic steps needing attention. When fossil records are limited, well-dated geological events are the main resource for calibration. However, biogeographic calibrations have often been used in a simplistic manner, for example assuming simultaneous vicariant divergence of multiple sister lineages...
February 10, 2018: Journal of Molecular Evolution
Serguei Liachenko, Jaivijay Ramu, Merle G Paule, Joseph Hanig
To assess the relative performance of MRI T2 relaxation and ADC mapping as potential biomarkers of neurotoxicity, a model of 3-nitropropionic acid (NP)-induced neurodegeneration in rats was employed. Male Sprague-Dawley rats received NP (N = 20, 16-20 mg/kg, ip or sc) or saline (N = 6, 2 ml/kg, ip) daily for 3 days. MRI was performed using a 7 tesla system employing quantitative T2 and ADC mapping based on spin echo pulse sequence. All maps were skull stripped and co-registered and the changes were quantified using baseline subtraction and anatomical segmentation...
February 7, 2018: Neurotoxicology
Chathura Kumaragamage, Dan Madularu, Axel P Mathieu, Derek Lupinsky, Robin A de Graaf, Jamie Near
PURPOSE: Indirect 13 C MRS by proton-observed carbon editing (POCE) is a powerful method to study brain metabolism. The sensitivity of POCE-MRS can be enhanced through the use of short TEs, which primarily minimizes homonuclear J-evolution related losses; previous POCE-MRS implementations use longer than optimal echo times due to sequence limitations, or short TE image selected in vivo spectroscopy-based multi-shot acquisitions for 3D localization. To that end, this paper presents a novel single-shot point resolved spectroscopy (PRESS)-localized POCE-MRS sequence that involves the application of simultaneous editing and localization pulses (SEAL)-PRESS, allowing the TE to be reduced to a theoretically optimal value of ∼ 1/JHC ...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Angus Z Lau, Justin Y C Lau, Albert P Chen, Charles H Cunningham
PURPOSE: To investigate the feasibility of performing large FOV hyperpolarized 13 C metabolic imaging using simultaneous multislice excitation. METHODS: A spectral-spatial multislice excitation pulse was constructed by cosine modulation and incorporated into a 13 C spiral imaging sequence. Phantom and in vivo pig experiments were performed to test the feasibility of simultaneous multislice data acquisition and image reconstruction. In vivo cardiac-gated images of hyperpolarized pyruvate, bicarbonate, and lactate were obtained at 1 × 1 × 1 cm3 resolution over a 48 × 48 × 24 cm3 FOV with 2-fold acceleration in the slice direction...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Armin Rund, Christoph Stefan Aigner, Karl Kunisch, Rudolf Stollberger
PURPOSE: Joint design of minimum duration RF pulses and slice-selective gradient shapes for MRI via time optimal control with strict physical constraints, and its application to simultaneous multislice imaging. THEORY AND METHODS: The minimization of the pulse duration is cast as a time optimal control problem with inequality constraints describing the refocusing quality and physical constraints. It is solved with a bilevel method, where the pulse length is minimized in the upper level, and the constraints are satisfied in the lower level...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Ping Gong, Pengfei Song, Shigao Chen
Contrast-enhanced ultrasound (CEUS) imaging has great potential for use in new ultrasound clinical applications such as myocardial perfusion imaging and abdominal lesion characterization. In CEUS imaging, contrast agents (i.e., microbubbles) are used to improve contrast between blood and tissue because of their high nonlinearity under low ultrasound pressure. However, the quality of CEUS imaging sometimes suffers from a low signal-to-noise ratio (SNR) in deeper imaging regions when a low mechanical index (MI) is used to avoid microbubble disruption, especially for imaging at off-resonance transmit frequencies...
February 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Alessandro Furlan, Amir A Borhani, Antonio C Westphalen
mp-MRI of the prostate is a complex study that combines anatomic and functional imaging. The complexity of this technique, along with an increasing demand, has brought new challenges to imaging interpretation. The Prostate Imaging Reporting and Data System provides radiologists with guidelines to standardize interpretation. This article discusses the interpretation of the pulse sequences recommended in the Prostate Imaging Reporting and Data System version 2 guidelines, reviews advanced quantitative imaging tools, and discusses future directions...
March 2018: Radiologic Clinics of North America
Marc-Antoine Sani, Pierre-Alexandre Martin, Ruhamah Yunis, Fangfang Chen, Maria Forsyth, Michael Deschamps, Luke A O'Dell
Dynamic nuclear polarisation (DNP) enhanced solid-state NMR spectroscopy has been used to study an ionic liquid salt solution (N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide, C3mpyrFSI, containing 1.0 m lithium bis(fluorosulfonyl)imide, 6LiFSI) in its glassy state at a temperature of 92 K. The incorporation of a biradical to enable DNP signal enhancement allowed the proximities of the lithium to the individual carbon sites on the pyrrolidinium cation to be probed using a 13C-6Li REDOR pulse sequence...
February 8, 2018: Journal of Physical Chemistry Letters
Houssein Gbaguidi-Haore, Amélie Varin, Pascal Cholley, Michelle Thouverez, Didier Hocquet, Xavier Bertrand
OBJECTIVE To describe an outbreak of multidrug-resistant Pseudomonas aeruginosa in which the hospital waste-pipe system was the likely source of contamination and to report the bundle of measures that facilitated the long-term control of the outbreak. DESIGN Outbreak investigation. SETTING The hematology unit of a tertiary-care referral center. PATIENTS Patients who were colonized or infected with P. aeruginosa belonging to the clonal outbreak. METHODS Patients admitted to our 15-bed stem-cell transplantation hematology unit were screened for P...
February 2018: Infection Control and Hospital Epidemiology
Lei Han, Hongqi Xia, Long Yin, Valery A Petrenko, Aihua Liu
The level of total prostate-specific antigen (t-PSA) is generally known as the key index of prostate cancer. Here, phage probes against t-PSA were selected from f8/8 landscape phage library. After three rounds of biopanning, four t-PSA-binding phage clones were isolated and identified by the DNA sequencing. Based on the phage capture assay, the phage clone displaying the fusion peptide ATRSANGM showed highest affinity and specificity against t-PSA. Subsequently, the t-PSA-specific phage was used as t-PSA capture probe in a sandwich enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV) assay systems...
February 2, 2018: Biosensors & Bioelectronics
Michael Kellman, Francois Rivest, Alina Pechacek, Lydia Sohn, Michael Lustig
A resistive pulse sensing device is able to extract quantities such as concentration and size distribution of particles, e.g. cells or microspheres, as they flow through the device's sensor region, i.e. channel, in an electrolyte solution. The dynamic range of detectable particle sizes is limited by the channel dimensions. In addition, signal interference from multiple particles transiting the channel simultaneously, i.e. coincidence event, further hinder the dynamic range. Coincidence data is often considered unusable and is discarded, reducing the throughput and introducing possible biases and errors into the distributions...
March 2017: Proceedings of the ... IEEE International Conference on Acoustics, Speech, and Signal Processing
Yu-Tzu Lin, Wei-Chun Hung, Jui-Chang Tsai, Kin Hong Leong, Hsiao-Jan Chen, Po-Ren Hsueh, Lee-Jene Teng
We examined the fusidic acid resistance determinants fusB, fusC, fusD, and fusF in coagulase-negative staphylococci (CoNS) clinical isolates. Among 208 resistant isolates, the fusB gene was the most common determinant in each species except in S. hominis subsp. hominis or in species carrying fusD or fusF. In S. hominis subsp. hominis, the fusC gene was the major determinant responsible for fusidic acid resistance. To understand the genetic context of fusC in S. hominis subsp. hominis, 31 fusC-positive S. hominis subsp...
January 30, 2018: International Journal of Antimicrobial Agents
Harald Busse, Thomas Kahn, Michael Moche
Efficient image guidance is the basis for minimally invasive interventions. In comparison with X-ray, computed tomography (CT), or ultrasound imaging, magnetic resonance imaging (MRI) provides the best soft tissue contrast without ionizing radiation and is therefore predestined for procedural control. But MRI is also characterized by spatial constraints, electromagnetic interactions, long imaging times, and resulting workflow issues. Although many technical requirements have been met over the years-most notably magnetic resonance (MR) compatibility of tools, interventional pulse sequences, and powerful processing hardware and software-there is still a large variety of stand-alone devices and systems for specific procedures only...
February 2018: Topics in Magnetic Resonance Imaging: TMRI
Emmanuel O Awosanya, Alexander A Nevzorov
A membrane-bound form of Pf1 coat protein reconstituted in magnetically aligned DMPC/DHPC bicelles was used as a molecular probe to quantify for the viscosity of the lipid membrane interior by measuring the uniaxial rotational diffusion coefficient of the protein. Orientationally dependent 15N NMR relaxation times in the rotating frame, or T1ρ, were determined by fitting individually the decay of the resolved NMR peaks corresponding to the transmembrane helix of Pf1 coat protein as a function of the spin-lock time incorporated into the 2D SAMPI4 pulse sequence...
January 23, 2018: Biophysical Journal
Cristina Olivieri, Manu Veliparambil Subrahmanian, Youlin Xia, Jonggul Kim, Fernando Porcelli, Gianluigi Veglia
Paramagnetic relaxation enhancement (PRE) measurements constitute a powerful approach for detecting both permanent and transient protein-protein interactions. Typical PRE experiments require an intrinsic or engineered paramagnetic site on one of the two interacting partners; while a second, diamagnetic binding partner is labeled with stable isotopes (15N or 13C). Multiple paramagnetic labeled centers or reversed labeling schemes are often necessary to obtain sufficient distance restraints to model protein-protein complexes, making this approach time consuming and expensive...
February 2, 2018: Journal of Biomolecular NMR
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