Detecting and screening clouds is the first step in most optical remote sensing analyses. Cloud formation is diverse, presenting many shapes, thicknesses, and altitudes. This variety poses a significant challenge to the development of effective cloud detection algorithms, as most datasets lack an unbiased representation.
View Article and Find Full Text PDFThe design and optimization of laser-Compton x-ray systems based on compact distributed charge accelerator structures can enable micron-scale imaging of disease and the concomitant production of beams of Very High Energy Electrons (VHEEs) capable of producing FLASH-relevant dose rates. The physics of laser-Compton x-ray scattering ensures that the scattered x-rays follow exactly the trajectory of the incident electrons, thus providing a route to image-guided, VHEE FLASH radiotherapy. The keys to a compact architecture capable of producing both laser-Compton x-rays and VHEEs are the use of X-band RF accelerator structures which have been demonstrated to operate with over 100 MeV/m acceleration gradients.
View Article and Find Full Text PDFRecurrent episodes of weakness in periodic paralysis are caused by intermittent loss of muscle fibre excitability, as a consequence of sustained depolarization of the resting potential. Repolarization is favoured by increasing the fibre permeability to potassium. Based on this principle, we tested the efficacy of retigabine, a potassium channel opener, to suppress the loss of force induced by a low-K+ challenge in hypokalaemic periodic paralysis (HypoPP).
View Article and Find Full Text PDFIntroduction: In the mid-fifties, Colombia adopted and implemented the Malaria Eradication Campaign (MEC), which has not been evaluated yet in the country.
Objective: To evaluate the results achieved during the attack and consolidation phases of the MEC regarding malaria transmission in Colombia between 1959 and 1979.
Materials And Methods: We conducted a descriptive and retrospective study based on the malariometric and operational results of the MEC in Colombia from 1959 to 1979 compiled from the archives of the Ministry of Public Health.
Initiation of skeletal muscle contraction is triggered by rapid activation of RYR1 channels in response to sarcolemmal depolarization. RYR1 is intracellular and has no voltage-sensing structures, but it is coupled with the voltage-sensing apparatus of CaV1.1 channels to inherit voltage sensitivity.
View Article and Find Full Text PDFMutations in the voltage sensor domain (VSD) of CaV1.1, the α1S subunit of the L-type calcium channel in skeletal muscle, are an established cause of hypokalemic periodic paralysis (HypoPP). Of the 10 reported mutations, 9 are missense substitutions of outer arginine residues (R1 or R2) in the S4 transmembrane segments of the homologous domain II, III (DIII), or IV.
View Article and Find Full Text PDFWe conducted a multicenter cohort study to determine the effect of drug therapies on survival in mechanically ventilated patients with coronavirus disease 2019. All consecutive adult patients admitted to ICU for coronavirus disease 2019 from March 1, 2020, to April 25, 2020, and under invasive mechanical ventilation for more than 24 hours were included. Out of 2,003 patients hospitalized for coronavirus disease 2019, 361 were admitted to ICU, 257 were ventilated for more than 24 hours, and 247 were included in the study.
View Article and Find Full Text PDFThe chloride gradient plays an important role in regulating cell volume, membrane potential, pH, secretion, and the reversal potential of inhibitory glycine and GABA receptors. Measurement of intracellular chloride activity, [Formula: see text], using liquid membrane ion-selective microelectrodes (ISM), however, has been limited by the physiochemical properties of Cl ionophores which have caused poor stability, drift, sluggish response times, and interference from other biologically relevant anions. Most importantly, intracellular [Formula: see text] may be up to 4 times more abundant than Cl (e.
View Article and Find Full Text PDFObjective: To identify the genetic and physiologic basis for recessive myasthenic congenital myopathy in 2 families, suggestive of a channelopathy involving the sodium channel gene, .
Methods: A combination of whole exome sequencing and targeted mutation analysis, followed by voltage-clamp studies of mutant sodium channels expressed in fibroblasts (HEK cells) and oocytes.
Results: Missense mutations of the same residue in the skeletal muscle sodium channel, R1460 of Na1.
Periodic paralysis is an ion channelopathy of skeletal muscle in which recurrent episodes of weakness or paralysis are caused by sustained depolarization of the resting potential and thus reduction of fiber excitability. Episodes are often triggered by environmental stresses, such as changes in extracellular K, cooling, or exercise. Rest after vigorous exercise is the most common trigger for weakness in periodic paralysis, but the mechanism is unknown.
View Article and Find Full Text PDFNursing professional development practitioners are encouraged to consider incorporating preferred learning styles into professional development programs. However, conclusive evidence about preferred learning styles does not exist. This study describes the preferred learning styles of nursing staff.
View Article and Find Full Text PDFThis study examined the molecular correlates of Down's dementia. qRTPCR for chromosome 21 microRNAs was correlated with in situ hybridization, immunohistochemistry for microRNA targets, mRNAs located on chromosome 21, and neurofibrillary tangles in human and the Ts65 dn mouse Down's model. qRTPCR for the microRNAs on the triplicated chromosome showed miR-155 dominance in brain tissues (14.
View Article and Find Full Text PDFUnderstanding the metabolic profile of neurons with the hyperphosphorylated tau protein characteristic of Alzheimer's disease is essential to unraveling new potential therapies and diagnostics for the surgical pathologist. We stratified 75 brain tissues from Alzheimer's disease into hyperphosphorylated tau positive or negative and did co-expression analyses and qRTPCR for importin-β and exportin-5 plus several bcl2 family members and compared the data to controls, Down's dementia and Parkinson's disease. There was a significant increase in the expression of importin-β and exportin-5 in Alzheimer's disease relative to the three other categories (each p value<0.
View Article and Find Full Text PDFMutations of Ca1.1, the pore-forming subunit of the L-type Ca channel in skeletal muscle, are an established cause of hypokalemic periodic paralysis (HypoPP). However, functional assessment of HypoPP mutant channels has been hampered by difficulties in achieving sufficient plasma membrane expression in cells that are not of muscle origin.
View Article and Find Full Text PDFThe absence of any histologic correlate for Alzheimer's disease despite its commonness and severe clinical sequelae may offers clues to its etiology. Recent evidence strongly suggests that the central event of this disease is the hyperphosphorylation of neuronal tau protein and not the beta amyloid precipitates. In each case, essential and soluble neuronal proteins derivatives form insoluble aggregates that can readily be detected by immunohistochemistry using antibodies specific for the misfolded proteins.
View Article and Find Full Text PDFDuchenne muscular dystrophy is caused by mutations in DMD which disrupt the reading frame. Therapeutic strategies that restore DMD's reading frame, such as exon skipping and CRISPR/Cas9, need to be tested in the context of the human DMD sequence in vivo. We have developed a novel dystrophic mouse model by using CRISPR/Cas9 to delete exon 45 in the human DMD gene in hDMD mice, which places DMD out-of-frame.
View Article and Find Full Text PDFInward rectifying potassium (Kir) channels play a central role in maintaining the resting membrane potential of skeletal muscle fibres. Nevertheless their role has been poorly studied in mammalian muscles. Immunohistochemical and transgenic expression were used to assess the molecular identity and subcellular localization of Kir channel isoforms.
View Article and Find Full Text PDFBackground: Exercise intolerance in chronic heart failure (HF) has been attributed to abnormalities of the skeletal muscles. Muscle function depends on intact excitation-contraction coupling (ECC), but ECC studies in HF models have been inconclusive, due to deficiencies in the animal models and tools used to measure calcium (Ca2+) release, mandating investigations in skeletal muscle from HF patients. The purpose of this study was to test the hypothesis that Ca2+ release is significantly impaired in the skeletal muscle of HF patients in whom exercise capacity is severely diminished compared to age-matched healthy volunteers.
View Article and Find Full Text PDFAbstract We combine electrophysiological and optical techniques to investigate the role that the expression of chloride channels (ClC-1) plays on the age-dependent electrical properties of mammalian muscle fibres. To this end, we comparatively evaluate the magnitude and voltage dependence of chloride currents (ICl), as well as the resting resistance, in fibres isolated from control and human skeletal actin (HSA)(LR) mice (a model of myotonic dystrophy) of various ages. In control mice, the maximal peak chloride current ([peak-ICl]max) increases from -583 ± 126 to -956 ± 260 μA cm(-2) (mean ± SD) between 3 and 6 weeks old.
View Article and Find Full Text PDFA two-microelectrode voltage clamp and optical measurements of membrane potential changes at the transverse tubular system (TTS) were used to characterize delayed rectifier K currents (IK(V)) in murine muscle fibers stained with the potentiometric dye di-8-ANEPPS. In intact fibers, IK(V) displays the canonical hallmarks of K(V) channels: voltage-dependent delayed activation and decay in time. The voltage dependence of the peak conductance (gK(V)) was only accounted for by double Boltzmann fits, suggesting at least two channel contributions to IK(V).
View Article and Find Full Text PDFWe investigated the effects of the overexpression of two enhanced green fluorescent protein (EGFP)-tagged α1sDHPR variants on Ca2+ currents (ICa), charge movements (Q) and SR Ca2+ release of muscle fibres isolated from adult mice. Flexor digitorum brevis (FDB)muscles were transfected by in vivo electroporation with plasmids encoding for EGFP-α1sDHPR-wt and EGFP-α1sDHPR-T935Y (an isradipine-insensitive mutant). Two-photon laser scanning microscopy (TPLSM) was used to study the subcellular localization of transgenic proteins, while ICa, Q and Ca2+ release were studied electrophysiologically and optically under voltage-clamp conditions.
View Article and Find Full Text PDFRepetitive activation of skeletal muscle fibers leads to a reduced transmembrane K(+) gradient. The resulting membrane depolarization has been proposed to play a major role in the onset of muscle fatigue. Nevertheless, raising the extracellular K(+) K(+)(O) concentration ([K(+)](O)) to 10 mM potentiates twitch force of rested amphibian and mammalian fibers.
View Article and Find Full Text PDFA growing interest in cell biology is to express transgenically modified forms of essential proteins (e.g. fluorescently tagged constructs and/or mutant variants) in order to investigate their endogenous distribution and functional relevance.
View Article and Find Full Text PDFTwo hybrid voltage-sensing systems based on fluorescence resonance energy transfer (FRET) were used to record membrane potential changes in the transverse tubular system (TTS) and surface membranes of adult mice skeletal muscle fibers. Farnesylated EGFP or ECFP (EGFP-F and ECFP-F) were used as immobile FRET donors, and either non-fluorescent (dipicrylamine [DPA]) or fluorescent (oxonol dye DiBAC(4)(5)) lipophilic anions were used as mobile energy acceptors. Flexor digitorum brevis (FDB) muscles were transfected by in vivo electroporation with pEGFP-F and pECFP-F.
View Article and Find Full Text PDF