-
JAMA Cardiology Oct 2022
Topics: Humans; Mitral Valve; Tachycardia, Paroxysmal; Tachycardia, Supraventricular
PubMed: 36069967
DOI: 10.1001/jamacardio.2022.2902 -
Ear, Nose, & Throat Journal Feb 2023Fatigue is thought of as a leading cause of iatrogenic accidents. A significant deterioration in qualitative balance function has been shown in sleep deprived...
BACKGROUND
Fatigue is thought of as a leading cause of iatrogenic accidents. A significant deterioration in qualitative balance function has been shown in sleep deprived individuals.
AIM/OBJECTIVES
To quantify the degree to which balance is impaired by sleep deprivation (SD) in post-call medical residents.
METHODS
Medical residents voluntarily underwent computed dynamic posturography (CDP) before and after an on-call night, at an identical time of the day. Order of test performance was random to avoid behavioral learning. Each participant served as his or her own control.
RESULTS
Seventeen residents were enrolled (median age 32years). Average sleeping duration the night before and during the night shift was 6.5 and 1 hour, respectively. The average response times difference between alert and fatigued was 10.15 milliseconds (95% CI: 6.81-13.49 milliseconds), yielding a significantly prolonged response times from 120 milliseconds before to 130 milliseconds after the night shift ( < .001). Comparison of additional measurements of CDP performance did not differ between test conditions.
CONCLUSION
Medical residents are fatigued due to the effect of on-call nights. Sleep deprivation prolongs response times to vestibular stimuli. This finding probably has an effect on execution of manual skills and may reflect a more generalized slowing of responses and overall performance impairment.
SIGNIFICANCE
The vestibular system is susceptible to SD.
Topics: Humans; Male; Female; Adult; Sleep Deprivation; Internship and Residency; Sleep; Sleep Duration; Work Schedule Tolerance; Fatigue
PubMed: 33393818
DOI: 10.1177/0145561320980242 -
Philosophical Transactions of the Royal... May 2015We discuss the importance of timing in brain function: how temporal dynamics of the world has left its traces in the brain during evolution and how we can monitor the... (Review)
Review
We discuss the importance of timing in brain function: how temporal dynamics of the world has left its traces in the brain during evolution and how we can monitor the dynamics of the human brain with non-invasive measurements. Accurate timing is important for the interplay of neurons, neuronal circuitries, brain areas and human individuals. In the human brain, multiple temporal integration windows are hierarchically organized, with temporal scales ranging from microseconds to tens and hundreds of milliseconds for perceptual, motor and cognitive functions, and up to minutes, hours and even months for hormonal and mood changes. Accurate timing is impaired in several brain diseases. From the current repertoire of non-invasive brain imaging methods, only magnetoencephalography (MEG) and scalp electroencephalography (EEG) provide millisecond time-resolution; our focus in this paper is on MEG. Since the introduction of high-density whole-scalp MEG/EEG coverage in the 1990s, the instrumentation has not changed drastically; yet, novel data analyses are advancing the field rapidly by shifting the focus from the mere pinpointing of activity hotspots to seeking stimulus- or task-specific information and to characterizing functional networks. During the next decades, we can expect increased spatial resolution and accuracy of the time-resolved brain imaging and better understanding of brain function, especially its temporal constraints, with the development of novel instrumentation and finer-grained, physiologically inspired generative models of local and network activity. Merging both spatial and temporal information with increasing accuracy and carrying out recordings in naturalistic conditions, including social interaction, will bring much new information about human brain function.
Topics: Brain; Brain Mapping; Electroencephalography; Humans; Magnetoencephalography; Nerve Net; Time Factors
PubMed: 25823867
DOI: 10.1098/rstb.2014.0170 -
Progress in Biophysics and Molecular... May 2019Flaviviruses are simple enveloped viruses exhibiting complex structural and functional heterogeneities. Decades of research have provided crucial basic insights,... (Review)
Review
Flaviviruses are simple enveloped viruses exhibiting complex structural and functional heterogeneities. Decades of research have provided crucial basic insights, antiviral medication and moderately successful gene therapy trials. The most infectious particle is, however, not always the most abundant one in a population, questioning the utility of classic ensemble-averaging virology approaches. Indeed, viral replication is often not particularly efficient, prone to errors or containing parallel routes. Here, we review different single-molecule sensitive fluorescence methods that are employed to investigate flaviviruses. In particular, we review how (i) time-resolved Förster resonance energy transfer (trFRET) was applied to probe dengue envelope conformations; (ii) FRET-fluorescence correlation spectroscopy to investigate dengue envelope intrinsic dynamics and (iii) single particle tracking to follow the path of dengue viruses in cells. We also discuss how such methods may be supported by molecular dynamics (MD) simulations over a range of spatio-temporal scales, to provide complementary data on the structure and dynamics of flaviviral systems. We describe recent improvements in multiscale MD approaches that allowed the simulation of dengue particle envelopes in near-atomic resolution. We hope this review is an incentive for setting up and applying similar single-molecule studies and combine them with MD simulations to investigate structural dynamics of entire flavivirus particles over the nanosecond-to-millisecond time-scale and follow viruses during infection in cells over milliseconds to minutes.
Topics: Diffusion; Flavivirus; Fluorescence Resonance Energy Transfer; Humans; Models, Molecular; Virion
PubMed: 30223001
DOI: 10.1016/j.pbiomolbio.2018.09.001 -
ELife Aug 2021Human standing balance relies on self-motion estimates that are used by the nervous system to detect unexpected movements and enable corrective responses and adaptations...
Human standing balance relies on self-motion estimates that are used by the nervous system to detect unexpected movements and enable corrective responses and adaptations in control. These estimates must accommodate for inherent delays in sensory and motor pathways. Here, we used a robotic system to simulate human standing about the ankles in the anteroposterior direction and impose sensorimotor delays into the control of balance. Imposed delays destabilized standing, but through training, participants adapted and re-learned to balance with the delays. Before training, imposed delays attenuated vestibular contributions to balance and triggered perceptions of unexpected standing motion, suggesting increased uncertainty in the internal self-motion estimates. After training, vestibular contributions partially returned to baseline levels and larger delays were needed to evoke perceptions of unexpected standing motion. Through learning, the nervous system accommodates balance sensorimotor delays by causally linking whole-body sensory feedback (initially interpreted as imposed motion) to self-generated balance motor commands.
Topics: Adult; Computer Simulation; Feedback, Sensory; Female; Humans; Learning; Male; Motion; Postural Balance; Posture; Robotics; Vestibule, Labyrinth; Young Adult
PubMed: 34374648
DOI: 10.7554/eLife.65085 -
Journal of Magnetic Resonance (San... Sep 2022We review recent efforts to develop and apply an experimental approach to the structural characterization of transient intermediate states in biomolecular processes that... (Review)
Review
We review recent efforts to develop and apply an experimental approach to the structural characterization of transient intermediate states in biomolecular processes that involve large changes in molecular conformation or assembly state. This approach depends on solid state nuclear magnetic resonance (ssNMR) measurements that are performed at very low temperatures, typically 25-30 K, with signal enhancements from dynamic nuclear polarization (DNP). This approach also involves novel technology for initiating the process of interest, either by rapid mixing of two solutions or by a rapid inverse temperature jump, and for rapid freezing to trap intermediate states. Initiation by rapid mixing or an inverse temperature jump can be accomplished in approximately-one millisecond. Freezing can be accomplished in approximately 100 microseconds. Thus, millisecond time resolution can be achieved. Recent applications to the process by which the biologically essential calcium sensor protein calmodulin forms a complex with one of its target proteins and the process by which the bee venom peptide melittin converts from an unstructured monomeric state to a helical, tetrameric state after a rapid change in pH or temperature are described briefly. Future applications of millisecond time-resolved ssNMR are also discussed briefly.
Topics: Magnetic Resonance Spectroscopy; Molecular Conformation; Nuclear Magnetic Resonance, Biomolecular; Peptides; Proteins
PubMed: 35998398
DOI: 10.1016/j.jmr.2022.107285 -
IScience Sep 2021Neurons in the visual cortex quickly adapt to constant input, which should lead to perceptual fading within few tens of milliseconds. However, perceptual fading is...
Neurons in the visual cortex quickly adapt to constant input, which should lead to perceptual fading within few tens of milliseconds. However, perceptual fading is rarely observed in everyday perception, possibly because eye movements refresh retinal input. Recently, it has been suggested that amplitudes of large saccadic eye movements are scaled to maximally decorrelate presaccadic and postsaccadic inputs and thus to annul perceptual fading. However, this argument builds on the assumption that adaptation within naturally brief fixation durations is strong enough to survive any visually disruptive saccade and affect perception. We tested this assumption by measuring the effect of luminance adaptation on postsaccadic contrast perception. We found that postsaccadic contrast perception was affected by presaccadic luminance adaptation during brief periods of fixation. This adaptation effect emerges within 100 milliseconds and persists over seconds. These results indicate that adaptation during natural fixation periods can affect perception even after visually disruptive saccades.
PubMed: 34485868
DOI: 10.1016/j.isci.2021.102986 -
Heart Failure Clinics Jan 2017Cardiac resynchronization therapy (CRT) is included in international consensus guidelines as a treatment with proven efficacy in well-selected patients on top of optimal... (Review)
Review
Cardiac resynchronization therapy (CRT) is included in international consensus guidelines as a treatment with proven efficacy in well-selected patients on top of optimal medical therapy. Although all the guidelines strongly recommend CRT for LBBB with QRS duration greater than 150 milliseconds, lower strength of recommendation is reported for QRS duration of 120 to 150 milliseconds, especially if not associated with LBBB. CRT is not recommended for a QRS of less than 120 milliseconds. No indication emerges for guiding the implant based on echocardiographic evaluation of dyssynchrony. Many data indicate that CRT is underused and there is heterogeneity in its implementation.
Topics: Cardiac Resynchronization Therapy; Clinical Trials as Topic; Heart Failure; Humans; Practice Guidelines as Topic; Treatment Outcome
PubMed: 27886918
DOI: 10.1016/j.hfc.2016.07.010 -
Frontiers in Psychology 2022Random Dot Motion (RDM) displays refer to clouds of independently moving dots that can be parametrically manipulated to provide a perception of the overall cloud moving...
Random Dot Motion (RDM) displays refer to clouds of independently moving dots that can be parametrically manipulated to provide a perception of the overall cloud moving coherently in a specified direction of motion. As a well-studied probe of motion perception, RDMs have been widely employed to understand underlying neural mechanisms of motion perception, perceptual decision-making, and perceptual learning, among other processes. Despite their wide use, RDM stimuli implementation is highly dependent on the parameters and the generation algorithm of the stimuli; both can greatly influence behavioral performance on RDM tasks. With the advent of the COVID pandemic and an increased need for more accessible platforms, we aimed to validate a novel RDM paradigm on Inquisit Millisecond, a platform for the online administration of cognitive and neuropsychological tests and assessments. We directly compared, in the same participants using the same display, a novel RDM paradigm on both Inquisit Millisecond and MATLAB with Psychtoolbox. We found that psychometric functions of Coherence largely match between Inquisit Millisecond and MATLAB, as do the effects of Duration. These data demonstrate that the Millisecond RDM provides data largely consistent with those previously found in laboratory-based systems, and the present findings can serve as a reference point for expected thresholds for when these procedures are used remotely on different platforms.
PubMed: 36562063
DOI: 10.3389/fpsyg.2022.1035518 -
Arthroscopy, Sports Medicine, and... Apr 2021To investigate neuromuscular electromyographic response of the of the upper and lower leg muscles after the application of an intraoperative, isolated mechanical...
PURPOSE
To investigate neuromuscular electromyographic response of the of the upper and lower leg muscles after the application of an intraoperative, isolated mechanical stimulus of the capsuloligamentous structures, including the anterior (ACL) and posterior cruciate ligaments (PCL), lateral (LM) and medial menisci (MM), plica mediopatellaris (PM), and Hoffa's fat pat (HFP).
METHODS
The electromyographic response of the upper and lower leg muscles (M. rectus femoris; M. vastus medialis; M. semitendinosus; M. biceps femoris; M. gastrocnemius lateralis) of 15 male patients were measured after an isolated mechanical stimulus of the capsuloligamentous structures during an arthroscopic intervention using a customized intraoperative setup. Target parameters were the short (SLR; <30 milliseconds) and medium latency responses (MLR; >30 milliseconds) after the mechanically-induced trigger.
RESULTS
The ACL, PCL, LM, and MM displayed high interindividual reproducibility of >76%. The MM was the only structure indicating both an SLR and MLR for all muscles. Although signals could be detected, there was no reproducibility in electromyographic signal activation for the HFP. The most rapid MLR was observed for the PM (quadriceps: 37 milliseconds).
CONCLUSIONS
Each stimulated structure displayed an individual MLR response, which allowed us to create neuromapping combining the anatomical and quantitative representations of the individual muscular activation patterns after isolated mechanical stimulation of the capsuloligamentous knee joint structures, corroborating our hypothesis.
LEVEL OF EVIDENCE
Diagnostic - Level II.
PubMed: 34027469
DOI: 10.1016/j.asmr.2020.12.009