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International Journal of Environmental... Jun 2020The aim of this study was to systematically review the current literature on the electromyographic (EMG) activity of six core muscles (the rectus abdominis, the internal...
The aim of this study was to systematically review the current literature on the electromyographic (EMG) activity of six core muscles (the rectus abdominis, the internal and external oblique, the transversus abdominis, the lumbar multifidus, and the erector spinae) during core physical fitness exercises in healthy adults. A systematic review of the literature was conducted on the Cochrane, EBSCO, PubMed, Scopus, and Web of Science electronic databases for studies from January 2012 to March 2020. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used. The inclusion criteria were as follows: a) the full text available in English; b) a cross-sectional or longitudinal (experimental or cohorts) study design; c) the reporting of electromyographic activity as a percentage of maximum voluntary contraction (% MVIC), millivolts or microvolts; d) an analysis of the rectus abdominis (RA), transversus abdominis (TA), lumbar multifidus (MUL), erector spinae (ES), and the internal (IO) or external oblique (EO); e) an analysis of physical fitness exercises for core training; and f) healthy adult participants. The main findings indicate that the greatest activity of the RA, EO, and ES muscles was found in free-weight exercises. The greatest IO activity was observed in core stability exercises, while traditional exercises showed the greatest MUL activation. However, a lack of research regarding TA activation during core physical fitness exercises was revealed, in addition to a lack of consistency between the studies when applying methods to measure EMG activity.
Topics: Cross-Sectional Studies; Electromyography; Exercise; Exercise Therapy; Humans; Muscle, Skeletal; Physical Fitness
PubMed: 32560185
DOI: 10.3390/ijerph17124306 -
Current Opinion in Chemical Biology Aug 2015Neurons tightly regulate the electrical potential difference across the plasma membrane with millivolt accuracy and millisecond resolution. Membrane voltage dynamics... (Review)
Review
Neurons tightly regulate the electrical potential difference across the plasma membrane with millivolt accuracy and millisecond resolution. Membrane voltage dynamics underlie the generation of an impulse, the transduction of impulses from one end of the neuron to the other, and the release of neurotransmitters. Imaging these voltage dynamics in multiple neurons simultaneously is therefore crucial for understanding how neurons function together within circuits in intact brains. Genetically encoded fluorescent voltage sensors have long been desired to report voltage in defined subsets of neurons with optical readout. In this review, we discuss the diverse strategies used to design and optimize protein-based voltage sensors, and highlight the chemical mechanisms by which different classes of reporters sense voltage. To guide neuroscientists in choosing an appropriate sensor for their applications, we also describe operating trade-offs of each class of voltage indicators.
Topics: Action Potentials; Animals; Biosensing Techniques; Cell Membrane; Fluorescent Dyes; Humans; Luminescent Proteins; Neurons; Protein Binding; Voltage-Sensitive Dye Imaging
PubMed: 26079047
DOI: 10.1016/j.cbpa.2015.05.003 -
Scientific Reports Oct 2019A salinity gradient propels a DNA molecule through a solid-state nanopore and generates an ionic current whose change allows for the detection of the translocation....
A salinity gradient propels a DNA molecule through a solid-state nanopore and generates an ionic current whose change allows for the detection of the translocation. Measurements and theoretical analyses reveal the role of diffusio-osmosis in driving these phenomena: After accounting for known salinity-dependent electrode effects, the measured current change caused by the presence of a DNA molecule inside the nanopore and the DNA translocation speed through it both increase with the magnitude of the applied salinity gradients. The effects are consistent with the theory of diffuisio-osmosis and strong enough to enable DNA translocations to overcome an applied retarding potential of tens of millivolts. This work illustrates how salinity gradients can be used to power and operate a nanopore sensor.
Topics: DNA; Diffusion; Electricity; Nanopores; Osmosis; Salinity; Time Factors
PubMed: 31636288
DOI: 10.1038/s41598-019-51049-4 -
Proceedings of the National Academy of... Aug 2019Current approaches for electric power generation from nanoscale conducting or semiconducting layers in contact with moving aqueous droplets are promising as they show...
Current approaches for electric power generation from nanoscale conducting or semiconducting layers in contact with moving aqueous droplets are promising as they show efficiencies of around 30%, yet even the most successful ones pose challenges regarding fabrication and scaling. Here, we report stable, all-inorganic single-element structures synthesized in a single step that generate electrical current when alternating salinity gradients flow along its surface in a liquid flow cell. Nanolayers of iron, vanadium, or nickel, 10 to 30 nm thin, produce open-circuit potentials of several tens of millivolt and current densities of several microA cm at aqueous flow velocities of just a few cm s The principle of operation is strongly sensitive to charge-carrier motion in the thermal oxide nanooverlayer that forms spontaneously in air and then self-terminates. Indeed, experiments suggest a role for intraoxide electron transfer for Fe, V, and Ni nanolayers, as their thermal oxides contain several metal-oxidation states, whereas controls using Al or Cr nanolayers, which self-terminate with oxides that are redox inactive under the experimental conditions, exhibit dramatically diminished performance. The nanolayers are shown to generate electrical current in various modes of application with moving liquids, including sliding liquid droplets, salinity gradients in a flowing liquid, and in the oscillatory motion of a liquid without a salinity gradient.
PubMed: 31358629
DOI: 10.1073/pnas.1906601116 -
Journal of Visualized Experiments : JoVE Jul 2022Ex vivo preparations enable the study of many neurophysiological processes in isolation from the rest of the body while preserving local tissue structure. This work...
Ex vivo preparations enable the study of many neurophysiological processes in isolation from the rest of the body while preserving local tissue structure. This work describes the preparation of rat sciatic nerves for ex vivo neurophysiology, including buffer preparation, animal procedures, equipment setup and neurophysiological recording. This work provides an overview of the different types of experiments possible with this method. The outlined method aims to provide 6 h of stimulation and recording on extracted peripheral nerve tissue in tightly controlled conditions for optimal consistency in results. Results obtained using this method are A-fibre compound action potentials (CAP) with peak-to-peak amplitudes in the millivolt range over the entire duration of the experiment. CAP amplitudes and shapes are consistent and reliable, making them useful to test and compare new electrodes to existing models, or the effects of interventions on the tissue, such as the use of chemicals, surgical alterations, or neuromodulatory stimulation techniques. Both conventional commercially available cuff electrodes with platinum-iridium contacts and custom-made conductive elastomer electrodes were tested and gave similar results in terms of nerve stimulus strength-duration response.
Topics: Action Potentials; Animals; Electric Conductivity; Electric Stimulation; Electrodes; Neurophysiology; Rats; Sciatic Nerve
PubMed: 35913135
DOI: 10.3791/63838 -
The Journal of Biological Chemistry Jun 2001The midpoint reduction potentials of the FAD cofactor in wild-type Methylophilus methylotrophus (sp. W3A1) electron-transferring flavoprotein (ETF) and the alphaR237A...
alpha Arg-237 in Methylophilus methylotrophus (sp. W3A1) electron-transferring flavoprotein affords approximately 200-millivolt stabilization of the FAD anionic semiquinone and a kinetic block on full reduction to the dihydroquinone.
The midpoint reduction potentials of the FAD cofactor in wild-type Methylophilus methylotrophus (sp. W3A1) electron-transferring flavoprotein (ETF) and the alphaR237A mutant were determined by anaerobic redox titration. The FAD reduction potential of the oxidized-semiquinone couple in wild-type ETF (E'(1)) is +153 +/- 2 mV, indicating exceptional stabilization of the flavin anionic semiquinone species. Conversion to the dihydroquinone is incomplete (E'(2) < -250 mV), because of the presence of both kinetic and thermodynamic blocks on full reduction of the FAD. A structural model of ETF (Chohan, K. K., Scrutton, N. S., and Sutcliffe, M. J. (1998) Protein Pept. Lett. 5, 231-236) suggests that the guanidinium group of Arg-237, which is located over the si face of the flavin isoalloxazine ring, plays a key role in the exceptional stabilization of the anionic semiquinone in wild-type ETF. The major effect of exchanging alphaArg-237 for Ala in M. methylotrophus ETF is to engineer a remarkable approximately 200-mV destabilization of the flavin anionic semiquinone (E'(2) = -31 +/- 2 mV, and E'(1) = -43 +/- 2 mV). In addition, reduction to the FAD dihydroquinone in alphaR237A ETF is relatively facile, indicating that the kinetic block seen in wild-type ETF is substantially removed in the alphaR237A ETF. Thus, kinetic (as well as thermodynamic) considerations are important in populating the redox forms of the protein-bound flavin. Additionally, we show that electron transfer from trimethylamine dehydrogenase to alphaR237A ETF is severely compromised, because of impaired assembly of the electron transfer complex.
Topics: Arginine; Base Sequence; Benzoquinones; DNA Primers; Electron-Transferring Flavoproteins; Flavoproteins; Kinetics; Methylophilus methylotrophus; Mutagenesis, Site-Directed; Oxidation-Reduction; Potentiometry; Quinones
PubMed: 11285259
DOI: 10.1074/jbc.M010853200 -
Nature Communications Feb 2024The need for ever-faster information processing requires exceptionally small devices that operate at frequencies approaching the terahertz and petahertz regimes. For the...
The need for ever-faster information processing requires exceptionally small devices that operate at frequencies approaching the terahertz and petahertz regimes. For the diagnostics of such devices, researchers need a spatiotemporal tool that surpasses the device under test in speed and spatial resolution. Consequently, such a tool cannot be provided by electronics itself. Here we show how ultrafast electron beam probe with terahertz-compressed electron pulses can directly sense local electro-magnetic fields in electronic devices with femtosecond, micrometre and millivolt resolution under normal operation conditions. We analyse the dynamical response of a coplanar waveguide circuit and reveal the impulse response, signal reflections, attenuation and waveguide dispersion directly in the time domain. The demonstrated measurement bandwidth reaches 10 THz and the sensitivity to electric potentials is tens of millivolts or -20 dBm. Femtosecond time resolution and the capability to directly integrate our technique into existing electron-beam inspection devices in semiconductor industry makes our femtosecond electron beam probe a promising tool for research and development of next-generation electronics at unprecedented speed and size.
PubMed: 38409203
DOI: 10.1038/s41467-024-45744-8 -
Physica Medica : PM : An International... Aug 2022The roles and responsibilities of medical physicists (MPs) are growing together with the evolving science and technology. The complexity of today's clinical trials...
INTRODUCTION
The roles and responsibilities of medical physicists (MPs) are growing together with the evolving science and technology. The complexity of today's clinical trials requires the skills and knowledge of MPs for their safe and efficient implementation. However, it is unclear to what extent the skillsets offered by MPs are being exploited in clinical trials across Europe.
METHODS
The EFOMP Working Group on the role of Medical Physics Experts in Clinical Trials has designed a survey that targeted all 36 current National Member Organisations, receiving a response from 31 countries. The survey included both quantitative and qualitative queries regarding the involvement of MPs in trial design, setup, and coordination, either as trial team members or principal investigators.
RESULTS
The extent of MPs involvement in clinical trials greatly varies across European countries. The results showed disparities between the roles played by MPs in trial design, conduct or data processing. Similarly, differences among the 31 European countries that responded to the survey were found regarding the existence of national bodies responsible for trials or the available training offered to MPs. The role of principal investigator or co-investigator was reported by 12 countries (39%), a sign of efficient collaboration with medical doctors in designing and implementing clinical studies.
CONCLUSION
Organisation of specific training courses and guideline development for clinical trial design and conduct would encourage the involvement of a larger number of MPs in all stages of trials across Europe, leading to a better standardisation of clinical practice.
Topics: Clinical Trials as Topic; Europe; Humans; Physician's Role; Surveys and Questionnaires
PubMed: 35717777
DOI: 10.1016/j.ejmp.2022.06.008 -
Methods in Molecular Biology (Clifton,... 2022The mitochondrial membrane potential (ΔψM) is the major component of the bioenergetic driving force responsible for most cellular ATP produced, and it controls a host...
The mitochondrial membrane potential (ΔψM) is the major component of the bioenergetic driving force responsible for most cellular ATP produced, and it controls a host of biological processes. In intact cells, assay readouts with commonly used fluorescence ΔψM probes are distorted by factors other than ΔψM. Here, we describe a protocol to calculate both ΔψM and plasma membrane potential (ΔψP) in absolute millivolts in intact single cells, or in populations of adherent, cultured cells. Our approach generates unbiased data that allows comparison of ΔψM between cell types with different geometry and ΔψP, and to follow ΔψM in time when ΔψP fluctuates. The experimental paradigm results in fluorescence microscopy time courses using a pair of cationic and anionic probes with internal calibration points that are subsequently computationally converted to millivolts on an absolute scale. The assay is compatible with wide field, confocal or two-photon microscopy. The method given here is optimized for a multiplexed, partial 96-well microplate format to record ΔψP and ΔψM responses for three consecutive treatment additions.
Topics: Cells, Cultured; Fluorescent Dyes; Membrane Potential, Mitochondrial; Microscopy, Fluorescence; Mitochondria
PubMed: 35771433
DOI: 10.1007/978-1-0716-2309-1_2 -
Kidney International Jun 1996Isolated renal proximal tubules of sea water fish net secrete fluid in vitro. The principal electrolytes in secreted fluid are Na, Cl, Mg and S. Transepithelial voltages... (Review)
Review
Isolated renal proximal tubules of sea water fish net secrete fluid in vitro. The principal electrolytes in secreted fluid are Na, Cl, Mg and S. Transepithelial voltages may be lumen-negative or -positive by a few millivolts, and transepithelial resistances are low partly due to high paracellular Na and Cl permeabilities. Transepithelial electrochemical potentials indicate secretion of Mg into the tubule lumen by active transport. As Mg concentration in secreted fluid rises, Na concentration falls. Surprisingly, these observations of fluid secretion are made in glomerular and aglomerular proximal tubules, suggesting a fundamental mechanism common to both. Central to this commonality appears to be their behavior as open Donnan systems. Mg actively secreted into the tubule lumen from which it cannot diffuse back into the peritubular medium causes the transepithelial secretion of diffusible Na and Cl. Water follows by osmosis. Since there is flow out of the distal end of the tubule Donnan equilibrium is not attained. Instead, a dynamic Donnan system is maintained, driven by active transport of Mg. A mathematical model of tubular electrolyte and fluid secretion confirms the operation of this open, dynamic Donnan system in aglomerular and glomerular proximal tubules.
Topics: Animals; Kidney; Kidney Glomerulus; Models, Biological; Water-Electrolyte Balance
PubMed: 8743451
DOI: 10.1038/ki.1996.221