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https://www.readbyqxmd.com/read/28798968/stretching-of-surface-tethered-polymers-in-pressure-driven-flow-under-confinement
#1
Tamal Roy, Kai Szuttor, Jens Smiatek, Christian Holm, Steffen Hardt
We study the effect of pressure-driven flow on a single surface-tethered DNA molecule confined between parallel surfaces. The influence of flow and channel parameters as well as the length of the molecules on their extension and orientation is explored. In the experiments the chain conformations are imaged by laser scanning confocal microscopy. We find that the fractional extension of the tethered DNA molecules mainly depends on the wall shear stress, with effects of confinement being very weak. Experiments performed with molecules of different contour length show that the fractional extension is a universal function of the product of the wall shear stress and the contour length, a result that can be obtained from a simple scaling relation...
August 11, 2017: Soft Matter
https://www.readbyqxmd.com/read/28795245/a-systematic-review-and-meta-analysis-of-the-treatment-of-anal-fissure
#2
REVIEW
R L Nelson, D Manuel, C Gumienny, B Spencer, K Patel, K Schmitt, D Castillo, A Bravo, A Yeboah-Sampong
BACKGROUND: Anal fissure has a very large number of treatment options. The choice is difficult. In an effort to assist in that, choice presented here is a systematic review and meta-analysis of all published treatments for anal fissure that have been studied in randomized controlled trials. METHODS: Randomized trials were sought in the Cochrane Controlled Trials Register, Medline, EMBASE and the trials registry sites clinicaltrials.gov and who/int/ictrp/search/en...
August 9, 2017: Techniques in Coloproctology
https://www.readbyqxmd.com/read/28794084/mechanically-induced-ectopy-via-stretch-activated-cation-nonselective-channels-is-caused-by-local-tissue-deformation-and-results-in-ventricular-fibrillation-if-triggered-on-the-repolarization-wave-edge-commotio-cordis
#3
T Alexander Quinn, Honghua Jin, Peter Lee, Peter Kohl
BACKGROUND: External chest impacts (commotio cordis) can cause mechanically induced premature ventricular excitation (PVEM) and, rarely, ventricular fibrillation (VF). Because block of stretch-sensitive ATP-inactivated potassium channels curtailed VF occurrence in a porcine model of commotio cordis, VF has been suggested to arise from abnormal repolarization caused by stretch activation of potassium channels. Alternatively, VF could result from abnormal excitation by PVEM, overlapping with normal repolarization-related electric heterogeneity...
August 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28789534/excited-state-wavepacket-dynamics-in-no2-probed-by-strong-field-ionization
#4
Ruaridh Forbes, Andrey E Boguslavskiy, Iain Wilkinson, Jonathan G Underwood, Albert Stolow
We present an experimental femtosecond time-resolved study of the 399 nm excited state dynamics of nitrogen dioxide using channel-resolved above threshold ionization (CRATI) as the probe process. This method relies on photoelectron-photoion coincidence and covariance to correlate the strong-field photoelectron spectrum with ionic fragments, which label the channel. In all ionization channels observed, we report apparent oscillations in the ion and photoelectron yields as a function of pump-probe delay. Further, we observe the presence of a persistent, time-invariant above threshold ionization comb in the photoelectron spectra associated with most ionization channels at long time delays...
August 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28789530/dissociation-dynamics-of-transient-anion-formed-via-electron-attachment-to-sulfur-dioxide
#5
K Gope, V S Prabhudesai, N J Mason, E Krishnakumar
We report the molecular dynamics of dissociative electron attachment to sulfur dioxide (SO2) by measuring the momentum distribution of fragment anions using the velocity slice imaging technique in the electron energy range of 2-10 eV. The S(-) channel results from symmetric dissociation which exhibits competition between the stretch mode and bending mode of vibration in the excited parent anion. The asymmetric dissociation of parent anions leads to the production of O(-) and SO(-) channels where the corresponding neutral fragments are formed in their ground as well as excited electronic states...
August 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28768667/trpv4-channels-contribute-to-renal-myogenic-autoregulation-in-neonatal-pigs
#6
Hitesh Soni, Dieniffer Peixoto-Neves, Anberitha T Matthews, Adebowale Adebiyi
Myogenic response, a phenomenon in which resistance size arteries and arterioles swiftly constrict or dilate in response to an acute elevation or reduction, respectively in intravascular pressure is a key component of renal autoregulation mechanisms. Although it is well-established that the renal system is functionally immature in neonates, mechanisms that regulate neonatal renal blood flow (RBF) remain poorly understood. In this study, we investigated the hypothesis that members of the transient receptor potential vanilloid (TRPV) channels are molecular components of renal myogenic constriction in newborns...
August 2, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28757442/endothelin-receptor-mediated-ca-2-signaling-in-coronary-arteries-after-experimentally-induced-ischemia-reperfusion-injury-in-rat
#7
Sarah Brøgger Kristiansen, Kristian A Haanes, Majid Sheykhzade, Lars Edvinsson
BACKGROUND: Acute myocardial infarction is one of the leading causes of death. It is caused by a blockage of a coronary artery leading to reduced blood flow to the myocardium and hence ischemic damage. In addition, a second wave of damage after the flow has been restored, named reperfusion injury greatly exacerbate the damage. For the latter, no medical treatment exist. In this study the aim was to characterize Ca(2+) sensitivity in coronary arteries following experimental ischemia/reperfusion injury...
July 27, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/28750098/the-unique-n-terminal-sequence-of-the-bkca-channel-%C3%AE-subunit-determines-its-modulation-by-%C3%AE-subunits
#8
Ramón A Lorca, Xiaofeng Ma, Sarah K England
Large conductance voltage- and Ca2+-activated K+ (BKCa) channels are essential regulators of membrane excitability in a wide variety of cells and tissues. An important mechanism of modulation of BKCa channel activity is its association with auxiliary subunits. In smooth muscle cells, the most predominant regulatory subunit of BKCa channels is the β1-subunit. We have previously described that BKCa channels with distinctive N-terminal ends (starting with the amino acid sequence MDAL, MSSN or MANG) are differentially modulated by the β1-subunit, but not by the β2...
2017: PloS One
https://www.readbyqxmd.com/read/28746858/modeling-of-biomechanics-and-biorheology-of-red-blood-cells-in-type-2-diabetes-mellitus
#9
Hung-Yu Chang, Xuejin Li, George Em Karniadakis
Erythrocytes in patients with type-2 diabetes mellitus (T2DM) are associated with reduced cell deformability and elevated blood viscosity, which contribute to impaired blood flow and other pathophysiological aspects of diabetes-related vascular complications. In this study, by using a two-component red blood cell (RBC) model and systematic parameter variation, we perform detailed computational simulations to probe the alteration of the biomechanical, rheological, and dynamic behavior of T2DM RBCs in response to morphological change and membrane stiffening...
July 25, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28746191/whole-exome-sequencing-unveils-a-frameshift-mutation-in-cngb3-for-cone-dystrophy-a-case-report-of-an-indian-family
#10
Shashank Gupta, Amit Chaurasia, Ekta Pathak, Rajeev Mishra, Vidya Nair Chaudhry, Prashaant Chaudhry, Ashim Mukherjee, Mousumi Mutsuddi
RATIONALE: Genetic elucidation of cone-dominated retinal dystrophies in Indian subcontinent is much needed to identify and catalog underlying genetic defects. In this context, the present study recruited a consanguineous Indian family affected with autosomal recessive cone dystrophy (CD). Considering the huge genetic heterogeneity and recessive inheritance of the disease, we chose to dissect out causal variant in this family by whole exome sequencing (WES). PATIENT CONCERNS: In the recruited family, three of the six siblings had complaints of poor visual acuity, photophobia, and disturbed colour vision since early childhood...
July 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28734293/the-stretching-force-on-a-tethered-polymer-in-pressure-driven-flow
#11
Kai Szuttor, Tamal Roy, Steffen Hardt, Christian Holm, Jens Smiatek
We use mesoscopic lattice-Boltzmann/molecular dynamics simulations to study the stretching behavior of a single tethered polymer in micro- and nanochannels. In particular, we are interested in the connection between fluid flow properties and the force on the polymer chain. An analytical expression for the stretching force is proposed, which linearly depends on the number of monomers and the boundary shear rate. In agreement with theory, the numerical findings reveal that the influence of hydrodynamic interactions can be ignored, which is also supported by results of additional Langevin dynamics simulations...
July 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28731145/piezo1-protein-induces-the-apoptosis-of-human-osteoarthritis-derived-chondrocytes-by-activating-caspase-12-the-signaling-marker-of-er-stress
#12
Xiao-Fei Li, Zhao Zhang, Zhu-Ke Chen, Zhao-Wei Cui, Hai-Ning Zhang
The present study was carried out to determine whether the mechanically activated cation channel Piezo1 protein plays a role as a signaling pathway which causes the apoptosis of human chondrocytes. The chondrocytes were isolated, cultured, and then subjected to mechanical stretch force for 0, 2, 12, 24 and 48 h, respectively. The expression levels of Piezo1 and the apoptosis-related protein caspase-12 were assessed by reverse transcription-quantitative polymerase chain reaction, as well as the apoptosis-related genes, B cell lymphoma/leukemia-2 (Bcl-2), Bcl-associated X protein (Bax) and Bcl-2-associated death promoter (BAD)...
September 2017: International Journal of Molecular Medicine
https://www.readbyqxmd.com/read/28728817/piezo2-in-cutaneous-and-proprioceptive-mechanotransduction-in-vertebrates
#13
E O Anderson, E R Schneider, S N Bagriantsev
Mechanosensitivity is a fundamental physiological capacity, which pertains to all life forms. Progress has been made with regard to understanding mechanosensitivity in bacteria, flies, and worms. In vertebrates, however, the molecular identity of mechanotransducers in somatic and neuronal cells has only started to appear. The Piezo family of mechanogated ion channels marks a pivotal milestone in understanding mechanosensitivity. Piezo1 and Piezo2 have now been shown to participate in a number of processes, ranging from arterial modeling to sensing muscle stretch...
2017: Current Topics in Membranes
https://www.readbyqxmd.com/read/28724548/bradykinin-does-not-acutely-sensitize-the-reflex-pressor-response-during-hindlimb-skeletal-muscle-stretch-in-decerebrate-rats
#14
Korynne S Rollins, Joshua R Smith, Peter J Esau, Evan A Kempf, Tyler D Hopkins, Steven W Copp
Hindlimb skeletal muscle stretch (i.e., selective activation of the muscle mechanoreflex) in decerebrate rats evokes reflex increases in blood pressure and sympathetic nerve activity. Bradykinin has been found to sensitize mechano-gated channels through a bradykinin B2 receptor-dependent mechanism. Moreover, bradykinin B2 receptor expression on sensory neurons is increased following chronic femoral artery ligation in the rat (a model of simulated peripheral artery disease). We tested the hypothesis that, in decerebrate, unanesthetized rats, the injection of bradykinin into the arterial supply of a hindlimb would acutely augment (i...
July 19, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28723241/the-effects-of-stretch-activation-on-ionic-selectivity-of-the-trek-2-k2p-k-channel
#15
Ehsan Nematian-Ardestani, Viwan Jarerattanachat, Prafulla Aryal, Mark S P Sansom, Stephen J Tucker
The TREK-2 (KCNK10) K2P potassium channel can be regulated by variety of polymodal stimuli including pressure. In a recent study, we demonstrated that this mechanosensitive K(+) channel responds to changes in membrane tension by undergoing a major structural change from its 'down' state to the more expanded 'up' state conformation. These changes are mostly restricted to the lower part of the protein within the bilayer, but are allosterically coupled to the primary gating mechanism located within the selectivity filter...
July 19, 2017: Channels
https://www.readbyqxmd.com/read/28707684/conformer-specific-nonadiabatic-reaction-dynamics-in-the-photodissociation-of-partially-deuterated-thioanisoles-c6h5s-ch2d-and-c6h5s-chd2
#16
So-Yeon Kim, Jeongmook Lee, Sang Kyu Kim
In this work, we have investigated nonadiabatic dynamics in the vicinity of conical intersections for predissociation reactions of partially deuterated thioanisole molecules: C6H5S-CH2D and C6H5S-CHD2. Each isotopomer has two distinct rotational conformers according to the geometrical position of D or H of the methyl moiety with respect to the molecular plane for C6H5S-CH2D or C6H5S-CHD2, respectively, as spectroscopically characterized in our earlier report [J. Lee, S.-Y. Kim and S. K. Kim, J. Phys. Chem. A, 2014, 118, 1850]...
July 26, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28705727/the-piezo1-protein-ion-channel-functions-in-human-nucleus-pulposus-cell-apoptosis-by-regulating-mitochondrial-dysfunction-and-the-endoplasmic-reticulum-stress-signal-pathway
#17
Xiao-Fei Li, Ping Leng, Zhao Zhang, Hai-Ning Zhang
The Piezo1 protein ion channel is a novel mechanical stretch-activated ion channel (SAC) closely related to mechanical signals. Mechanotransduction plays a crucial role in organ development and homeostasis. Previous studies identified Piezo1 and demonstrated that it is distinct from other ion channels with well-established roles in lower organisms. Mechanical stretch-activated ion channels from other organisms are not conserved in mammals or do not act as mechanically activated channels in mammals. In the current study, we explored the role of the Piezo1 ion channel in human nucleus pulposus cell (NP cell) apoptosis through mechanical force-induced mitochondrial dysfunction and endoplasmic reticulum stress...
July 10, 2017: Experimental Cell Research
https://www.readbyqxmd.com/read/28702845/regulation-of-cardiac-ca-2-and-ion-channels-by-shear-mechanotransduction
#18
REVIEW
Joon-Chul Kim, Min-Jeong Son, Jun Wang, Sun-Hee Woo
Cardiac contraction is controlled by a Ca(2+) signaling sequence that includes L-type Ca(2+) current-gated opening of Ca(2+) release channels (ryanodine receptors) in the sarcoplasmic reticulum (SR). Local Ca(2+) signaling in the atrium differs from that in the ventricle because atrial myocytes lack transverse tubules and have more abundant corbular SR. Myocardium is subjected to a variety of forces with each contraction, such as stretch, shear stress, and afterload, and adapts to those mechanical stresses...
July 12, 2017: Archives of Pharmacal Research
https://www.readbyqxmd.com/read/28702524/nonadiabatic-dynamics-simulation-of-keto-isocytosine-a-comparison-of-dynamical-performance-of-different-electronic-structure-methods
#19
Deping Hu, Yan Fang Liu, Andrzej L Sobolewski, Zhenggang Lan
The nonadiabatic dynamics of keto isocytosine in the gas phase has been investigated using the on-the-fly trajectory surface hopping method based on two electronic-structure methods: SA-CASSCF and ADC(2). The results estimate an excited-state lifetime of around 1000 fs at the SA-CASSCF level, while a much shorter lifetime of 250-350 fs is obtained at the ADC(2) level. Although three conical intersections (CIs) (Ethyl. I, Ethyl. II and C[double bond, length as m-dash]O stretching) are relevant to the nonadiabatic decay of keto isocytosine, their contributions to the nonadiabatic decay are highly dependent on the electronic-structure methods employed in the dynamics simulation...
July 26, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28699288/different-characteristics-of-cell-volume-and-intracellular-calcium-ion-concentration-dynamics-between-the-hippocampal-ca1-and-lateral-cerebral-cortex-of-male-mouse-brain-slices-during-exposure-to-hypotonic-stress
#20
Nanae Takahashi, Akibumi Omi, Hiroyuki Uchino, Yoshihisa Kudo
The mechanism of brain edema is complex and still remains unclear. Our aim was to investigate the regional differences of cell volume and intracellular Ca(2+) concentration ([Ca(2+) ]i ) dynamics during hypotonic stress in male mouse hemi-brain slices. Brain slices were loaded with the fluorescence Ca(2+) indicator fura-2, and cell volume and [Ca(2+) ]i in the lateral cerebral cortex (LCC) and hippocampal CA1 (CA1) region were measured simultaneously during exposure to hypotonic stress using Ca(2+) insensitive (F360) and Ca(2+) sensitive fluorescence (F380), respectively...
July 12, 2017: Journal of Neuroscience Research
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