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https://www.readbyqxmd.com/read/27911759/neurotransmitter-release-can-be-stabilized-by-a-mechanism-that-prevents-voltage-changes-near-the-end-of-action-potentials-from-affecting-calcium-currents
#1
Stephen G Clarke, Matthew S Scarnati, Kenneth G Paradiso
: At chemical synapses, presynaptic action potentials (APs) activate voltage-gated calcium channels, allowing calcium to enter and trigger neurotransmitter release. The duration, peak amplitude, and shape of the AP falling phase alter calcium entry, which can affect neurotransmitter release significantly. In many neurons, APs do not immediately return to the resting potential, but instead exhibit a period of depolarization or hyperpolarization referred to as an afterpotential. We hypothesized that presynaptic afterpotentials should alter neurotransmitter release by affecting the electrical driving force for calcium entry and calcium channel gating...
November 9, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27899247/association-of-plasma-fetuin-a-levels-with-peripheral-arterial-disease-and-lower-extremity-arterial-calcification-in-subjects-with-type-2-diabetes-mellitus
#2
Ioanna Eleftheriadou, Pinelopi Grigoropoulou, Alexander Kokkinos, Iordanis Mourouzis, Despoina Perrea, Nicholas Katsilambros, Petros P Sfikakis, Nikolaos Tentolouris
AIMS: Fetuin-A is a hepatic glycoprotein that is involved in insulin resistance and atherosclerosis. Herein we examined the association of plasma fetuin-A levels with peripheral arterial disease (PAD) in patients with type 2 diabetes mellitus (T2DM). MATERIAL AND METHODS: A total of 71 patients with T2DM and 57 non-diabetic individuals were recruited. Diagnosis of PAD was based on the absence of triphasic waveform at pedal arteries, while ankle-brachial index (ABI) was calculated...
November 12, 2016: Journal of Diabetes and its Complications
https://www.readbyqxmd.com/read/27859425/maximizing-fluid-delivered-by-bubble-free-electroosmotic-pump-with-optimum-pulse-voltage-waveform
#3
Mena E Tawfik, Francisco J Diez
In generating high electroosmotic flows (EO) for use in microfluidic pumps, a limiting factor is faradaic reactions which are more pronounced at high electric fields. These reactions lead to bubble generation at the electrodes and pump efficiency reduction. The onset of gas generation for high current density EO pumping depends on many parameters including applied voltage, working fluid and pulse duration. The onset of gas generation can be delayed and optimized for maximum volume pumped in the minimum time possible...
November 17, 2016: Electrophoresis
https://www.readbyqxmd.com/read/27852807/mechanical-tuning-of-mammalian-sperm-behaviour-by-hyperactivation-rheology-and-substrate-adhesion-a-numerical-exploration
#4
Kenta Ishimoto, Eamonn A Gaffney
The great mammalian sperm race encounters numerous microenvironments to which sperm must adapt and a fundamental sperm response is the change in its waveform owing to both fluid rheology and capacitation, with the latter associated with a hyperactivated beat pattern. Hence, in this modelling study, we examine the effect of different flagellar waveforms for sperm behaviour near adhesive substrates, which are representative of epithelia in female tract sperm reservoirs and the zona pellucida (ZP), which surrounds the mammalian egg...
November 2016: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/27814311/effects-of-acoustic-stimulus-duration-on-cervical-vestibular-evoked-myogenic-potentials-a-neurophysiological-and-modeling-study
#5
A Ciardo, N El Assawy, S Mauro, L Priano
OBJECTIVE: To analyze and model the effects of acoustic stimulus duration on cervical vestibular evoked myogenic potentials (cVEMPs). DESIGN: Subjects with normal hearing and no vestibular or cervical disorders were tested using 1 kHz tone bursts (TBs) of different durations to evoke cVEMPs from the ipsilateral sternocleidomastoid muscle. VEMP modeling was performed in Labview. RESULTS: The increase in TB duration initially resulted in a non-linear increase in cVEMP amplitude, followed by more complex cVEMP modifications that were mainly related to the appearance of a new wave (nX) that interfered with n23...
November 3, 2016: Journal of Vestibular Research: Equilibrium & Orientation
https://www.readbyqxmd.com/read/27812293/atrial-electrophysiological-remodeling-and-fibrillation-in-heart-failure
#6
REVIEW
Sandeep V Pandit, Antony J Workman
Heart failure (HF) causes complex, chronic changes in atrial structure and function, which can cause substantial electrophysiological remodeling and predispose the individual to atrial fibrillation (AF). Pharmacological treatments for preventing AF in patients with HF are limited. Improved understanding of the atrial electrical and ionic/molecular mechanisms that promote AF in these patients could lead to the identification of novel therapeutic targets. Animal models of HF have identified numerous changes in atrial ion currents, intracellular calcium handling, action potential waveform and conduction, as well as expression and signaling of associated proteins...
2016: Clinical Medicine Insights. Cardiology
https://www.readbyqxmd.com/read/27811299/a-general-relationship-links-gait-mechanics-and-running-ground-reaction-forces
#7
Kenneth P Clark, Laurence J Ryan, Peter G Weyand
The relationship between gait mechanics and running ground reaction forces is widely regarded as complex. This viewpoint has evolved primarily via efforts to explain the rising-edge of vertical force-time waveforms observed during slow human running. Existing theoretical models do provide good rising-edge fits, but require more than a dozen input variables to sum the force contributions of four or more vague components of the body's total mass (mb). Here, we hypothesized that the force contributions of two discrete body mass components are sufficient to account for vertical ground reaction force-time waveforms patterns in full [stance foot and shank, m1=0...
November 3, 2016: Journal of Experimental Biology
https://www.readbyqxmd.com/read/27792151/elimination-of-drifts-in-long-duration-monitoring-for-apnea-hypopnea-of-human-respiration
#8
Peng Jiang, Rong Zhu
This paper reports a methodology to eliminate an uncertain baseline drift in respiratory monitoring using a thermal airflow sensor exposed in a high humidity environment. Human respiratory airflow usually contains a large amount of moisture (relative humidity, RH > 85%). Water vapors in breathing air condense gradually on the surface of the sensor so as to form a thin water film that leads to a significant sensor drift in long-duration respiratory monitoring. The water film is formed by a combination of condensation and evaporation, and therefore the behavior of the humidity drift is complicated...
October 25, 2016: Sensors
https://www.readbyqxmd.com/read/27777829/non-invasive-neuromodulation-using-time-varying-caloric-vestibular-stimulation
#9
Robert D Black, Lesco L Rogers, Kristen K Ade, Heather A Nicoletto, Heather D Adkins, Daniel T Laskowitz
Caloric vestibular stimulation (CVS) to elicit the vestibulo-ocular reflex has long been used in clinical settings to aid in the diagnosis of balance disorders and to confirm the absence of brainstem function. While a number of studies have hinted at the potential therapeutic applications of CVS, the limitations of existing devices have frustrated that potential. Current CVS irrigators use water or air during short-duration applications; however, this approach is not tenable for longer duration therapeutic protocols or home use...
2016: IEEE Journal of Translational Engineering in Health and Medicine
https://www.readbyqxmd.com/read/27774641/high-resolution-gradient-recalled-echo-imaging-at-9-4t-using-16-channel-parallel-transmit-simultaneous-multislice-spokes-excitations-with-slice-by-slice-flip-angle-homogenization
#10
Desmond H Y Tse, Christopher J Wiggins, Benedikt A Poser
PURPOSE: In order to fully benefit from the improved signal-to-noise and contrast-to-noise ratios at 9.4T, the challenges of B1+ inhomogeneity and the long acquisition time of high-resolution 2D gradient-recalled echo (GRE) imaging were addressed. THEORY AND METHODS: Flip angle homogenized excitations were achieved by parallel transmission (pTx) of 3-spoke pulses, designed by magnitude least-squares optimization in a slice-by-slice fashion; the acquisition time reduction was achieved by simultaneous multislice (SMS) pulses...
October 23, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27754865/central-hemodynamics-and-arterial-stiffness-in-systemic-sclerosis
#11
Elena Bartoloni, Giacomo Pucci, Francesca Cannarile, Francesca Battista, Alessia Alunno, Marco Giuliani, Giacomo Cafaro, Roberto Gerli, Giuseppe Schillaci
Although microvascular disease is a hallmark of systemic sclerosis (SSc), a higher prevalence of macrovascular disease and a poorer related prognosis have been reported in SSc than in the general population. The simultaneous assessment of prognostically relevant functional properties of larger and smaller arteries, and their effects on central hemodynamics, has never been performed in SSc using the state-of-the-art techniques. Thirty-four women with SSc (aged 61±15 years, disease duration 17±12 years, and blood pressure 123/70±18/11 mm Hg) and 34 healthy women individually matched by age and mean arterial pressure underwent the determination of carotid-femoral (aortic) and carotid-radial (upper limb) pulse wave velocity (a direct measure of arterial stiffness), aortic augmentation (a measure of the contribution of reflected wave to central pulse pressure), and aortobrachial pulse pressure amplification (brachial/aortic pulse pressure) through applanation tonometry (SphygmoCor)...
October 17, 2016: Hypertension
https://www.readbyqxmd.com/read/27692928/variability-in-response-to-quadripulse-stimulation-of-the-motor-cortex
#12
Koichiro Nakamura, Stefan Jun Groiss, Masashi Hamada, Hiroyuki Enomoto, Suguru Kadowaki, Mitsunari Abe, Takenobu Murakami, Winnugroho Wiratman, Fangyu Chang, Shunsuke Kobayashi, Ritsuko Hanajima, Yasuo Terao, Yoshikazu Ugawa
BACKGROUND: Responses to plasticity-inducing brain stimulation protocols are highly variable. However, no data are available concerning the variability of responses to quadripulse stimulation (QPS). OBJECTIVE: We assessed the QPS parameters of motor cortical plasticity induction in a systematic manner, and later investigated the variability of QPS using optimal parameters. METHODS: First, two different interburst intervals (IBI) with the same total number of pulses were compared...
November 2016: Brain Stimulation
https://www.readbyqxmd.com/read/27671752/effects-of-volume-pitch-and-phonation-type-on-oscillation-initiation-and-termination-phases-investigated-with-high-speed-videoendoscopy
#13
Melda Kunduk, Takeshi Ikuma, David C Blouin, Andrew J McWhorter
OBJECTIVES: This study aimed to investigate the effects of varying volume, pitch, and phonation types on the initiation and termination phases of vocal fold oscillation using high-speed digital videoendoscopy. Specifically, it addressed the effects of the variation of volume, pitch, and phonation type (normal, pressed, and breathy) on the transient duration of the vibrating glottal length (length transient duration, Tlen), the transient duration of the glottal area waveform (area transient duration, Tarea), the time offset between the beginning (or the end) of the full-length vibration and the full-amplitude vibration, TΔ, and the variation of the fundamental frequency during the vocal fold oscillation initiation and termination segments (pitch instability, %PI)...
September 23, 2016: Journal of Voice: Official Journal of the Voice Foundation
https://www.readbyqxmd.com/read/27666091/acoustic-temporal-aspects-of-stop-plosives-in-the-speech-of-persian-speaking-children-with-cleft-lip-and-palate
#14
Marziye Eshghi, John S Preisser, Mahmood Bijankhan, David J Zajac
PURPOSE: The main objective was to examine temporal parameters of stop-plosives in Persian-speaking children with repaired cleft lip and palate (CLP). METHOD: Eleven children with repaired bilateral CLP and 20 typically-developing children participated in the study. Stop-gap duration (SGD) and voice-onset time (VOT) were measured based on digital waveform and spectrographic displays. RESULT: Separate linear mixed model analyses showed significantly longer SGDs for children with CLP for all plosives in word-mid and final positions...
September 26, 2016: International Journal of Speech-language Pathology
https://www.readbyqxmd.com/read/27663507/does-end-tidal-capnography-confirm-tracheal-intubation-in-fresh-frozen-cadavers
#15
Cliff Reid, Ian Ferguson, Brian Burns, Karel Habig, Mohammed Shareef
BACKGROUND: Life-like end-tidal capnography (ETCO2) waveforms have been demonstrated in recently deceased and fresh-frozen cadavers following tracheal intubation, offering potential for high fidelity airway simulation training. As the mechanism for carbon dioxide production is not fully understood, it is possible that oesophageal intubation may also generate a capnograph. Our aim was to measure ETCO2 levels following (1) oesophageal and (2) tracheal intubation in fresh-frozen cadavers, and to observe the size, shape and duration of any capnographic waveform...
September 23, 2016: Emergency Medicine Journal: EMJ
https://www.readbyqxmd.com/read/27645393/rapid-speed-modulation-of-a-rotary-total-artificial-heart-impeller
#16
Matthias Kleinheyer, Daniel L Timms, Geoffrey D Tansley, Frank Nestler, Nicholas A Greatrex, O Howard Frazier, William E Cohn
Unlike the earlier reciprocating volume displacement-type pumps, rotary blood pumps (RBPs) typically operate at a constant rotational speed and produce continuous outflow. When RBP technology is used in constructing a total artificial heart (TAH), the pressure waveform that the TAH produces is flat, without the rise and fall associated with a normal arterial pulse. Several studies have suggested that pulseless circulation may impair microcirculatory perfusion and the autoregulatory response and may contribute to adverse events such as gastrointestinal bleeding, arteriovenous malformations, and pump thrombosis...
September 2016: Artificial Organs
https://www.readbyqxmd.com/read/27608904/influence-of-physical-effort-on-aortic-stiffness-in-young-male-athletes
#17
M Staniszewska, A Pudło, K Ryterska, E Stachowska
OBJECTIVE: The progression of cardiovascular disease is blunted by regular exercise training as a common non-pharmacological treatment. Recent findings have confirmed that central aortic pressure is more strongly related to cardiovascular events than brachial blood pressure. The aim of the study was to evaluate the influence of a single bout of significant physical effort on central aortic pressure and pulse wave velocity in young male athletes. PATIENTS AND METHODS: The study group consisted of 16 healthy male athletes undergoing regular endurance training...
August 2016: European Review for Medical and Pharmacological Sciences
https://www.readbyqxmd.com/read/27604100/noninvasive-assessment-of-pulmonary-arterial-capacitance-by-pulmonary-annular-motion-velocity-in-children-with-ventricular-septal-defect
#18
Yasunobu Hayabuchi, Akemi Ono, Yukako Homma, Shoji Kagami
BACKGROUND: We hypothesized that longitudinal pulmonary arterial deformation during the cardiac cycle reflects pulmonary arterial capacitance. To examine this hypothesis, we assessed whether tissue Doppler-derived pulmonary annular motion could serve as a novel way to evaluate pulmonary arterial capacitance in pediatric patients with ventricular septal defect (VSD). METHODS: In this prospective study, pulmonary annular velocity was measured in children (age, 6 months-5 years) with a preoperative VSD (VSD group, n = 35) and age-matched healthy children (Control group, n = 23)...
September 7, 2016: Cardiovascular Ultrasound
https://www.readbyqxmd.com/read/27576070/the-efficacy-of-electrical-stimulation-in-lower-extremity-cutaneous-wound-healing-a-systematic-review
#19
Mohammed Ashrafi, Teresa Alonso-Rasgado, Mohamed Baguneid, Ardeshir Bayat
Current gold standard lower extremity cutaneous wound management is not always effective. Cutaneous wounds generate a "current of injury" which is directly involved in wound healing processes. Application of exogenous electrical stimulation has been hypothesised to imitate the natural electric current that occurs in cutaneous wounds. The aim of this extensive review is to provide a detailed update on the variety of electrical stimulation modalities used in the management of lower extremity wounds. Several different waveforms and delivery methods of electrical stimulation have been used...
August 30, 2016: Experimental Dermatology
https://www.readbyqxmd.com/read/27554423/qrs-complex-waveform-indicators-of-ventricular-activation-slowing-simulation-studies
#20
Ljuba Bacharova, Vavrinec Szathmary, Jana Svehlikova, Anton Mateasik, Milan Tysler
Diffuse or regional activation slowing in ventricular myocardium can result from different cardiac pathologies, such as left ventricular hypertrophy, ischemia or fibrosis. Altered ventricular activation sequence leads to deformations of the activation front and consequently to the changes in the QRS complex. Using a computer model we simulated the effect of slowed ventricular activation on the QRS waveform with a special interest in ECG changes which reproduce the ECG criteria of left ventricular hypertrophy (ECG-LVH)...
August 5, 2016: Journal of Electrocardiology
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