Recovery Course of Excitability in A Single Neurone of Onchidium Verruculatum

1971 ◽  
Vol 54 (2) ◽  
pp. 471-484
Author(s):  
YOSHIFUMI KATAYAMA
Keyword(s):  
Nerve Cell ◽  
Resting State ◽  
Time Course ◽  
Current Strength ◽  
Time Interval ◽  
Electrical Excitability ◽  
Glass Capillary ◽  
Time Duration ◽  
Minimum Quantity ◽  
Pass Through

The electrical excitability of a nerve cell of Onchidium verruculatum was measured by transmembrane depolarizing current pulses through a glass-capillary microelectrode inserted into the soma of the nerve cell. 1. The strength-duration and the strength-latency relations were measured during the resting state of a silent-type nerve cell, and both were represented by hyperbolic curves. This shows that the minimum quantity of electricity (that is, current strength multiplied by time duration required to produce a spike) must pass through the membrane to discharge impulses in the resting state of the nerve cell. 2. The strength-latency relations were obtained after a spontaneous spike. The stimulus began during the falling phase of a preceding firing and lasted for 300 ms. These relations were represented by two exponential terms. 3. The strength-duration relations were measured at various times after a preceding discharge and these were also represented approximately by hyperbolic curves in regularly firing or frequently firing neurones. These results suggested that a minimum quantity of electricity must be required to elicit a second spike at a given time interval after a preceding spike; and that the reciprocal of this value might represent the excitability after that time interval. 4. The time course of the reciprocal of the quantity referred to above expresses the process of the recovery of excitability in the nerve cell after a spike. This process can be expressed mathematically by two exponential terms.

Is cyclic guanosine monophosphate the internal 'second messenger' for cholinergic actions on central neurons?

1976 ◽  
Vol 54 (2) ◽  
pp. 172-176 ◽  
Author(s):  
K. Krnjević ◽  
E. Puil ◽  
R. Werman
Keyword(s):  
Time Course ◽  
Membrane Conductance ◽  
Cyclic Guanosine Monophosphate ◽  
Guanosine Monophosphate ◽  
Resting Potential ◽  
Electrical Excitability ◽  
Spinal Motoneurons ◽  
Central Neurons ◽  
Intracellular Cgmp ◽  
Post Synaptic Potential

The most consistent effects produced by intracellular injections of guanosine 3′,5′-cyclic monophosphate (cGMP) (but not 5′-guanosine 5′-monophosphate in spinal motoneurons of cats are a rise in membrane conductance, acceleration in time course of spike potentials, and accentuation of the post-spike hyperpolarization. Associated changes in resting potential are smaller, less constant, and more often in the depolarizing than hyperpolarizing direction. cGMP tends to increase electrical excitability but reduces excitatory post-synaptic potential amplitudes. Most of the effects of intracellular cGMP are quite different from, or indeed opposite to, those of either extra- or intracellular applications of acetylcholine and therefore not consistent with the proposal that cGMP is the internal mediator of muscarinic actions.

scholarly journals Coupling Disease-Progress-Curve and Time-of-Infection Functions for Predicting Yield Loss of Crops

2000 ◽  
Vol 90 (8) ◽  
pp. 788-800 ◽  
Author(s):  
L. V. Madden ◽  
G. Hughes ◽  
M. E. Irwin
Keyword(s):  
Yield Loss ◽  
Numerical Solutions ◽  
Disease Incidence ◽  
Time Interval ◽  
Short Time Interval ◽  
Time Duration ◽  
Plant Yield ◽  
Disease Progress ◽  
Time Of Infection ◽  
Over Time

A general approach was developed to predict the yield loss of crops in relation to infection by systemic diseases. The approach was based on two premises: (i) disease incidence in a population of plants over time can be described by a nonlinear disease progress model, such as the logistic or monomolecular; and (ii) yield of a plant is a function of time of infection (t) that can be represented by the (negative) exponential or similar model (ζ(t)). Yield loss of a population of plants on a proportional scale (L) can be written as the product of the proportion of the plant population newly infected during a very short time interval (X′(t)dt) and ζ(t), integrated over the time duration of the epidemic. L in the model can be expressed in relation to directly interpretable parameters: maximum per-plant yield loss (α, typically occurring at t = 0); the decline in per-plant loss as time of infection is delayed (γ; units of time-1); and the parameters that characterize disease progress over time, namely, initial disease incidence (X0), rate of disease increase (r; units of time-1), and maximum (or asymptotic) value of disease incidence (K). Based on the model formulation, L ranges from αX0 to αK and increases with increasing X0, r, K, α, and γ-1. The exact effects of these parameters on L were determined with numerical solutions of the model. The model was expanded to predict L when there was spatial heterogeneity in disease incidence among sites within a field and when maximum per-plant yield loss occurred at a time other than the beginning of the epidemic (t > 0). However, the latter two situations had a major impact on L only at high values of r. The modeling approach was demonstrated by analyzing data on soybean yield loss in relation to infection by Soybean mosaic virus, a member of the genus Potyvirus. Based on model solutions, strategies to reduce or minimize yield losses from a given disease can be evaluated.

Concentration Gradient Effect on the Capturing Ratio of Nanopore for DNA

2015 ◽  
Vol 656-657 ◽  
pp. 554-560
Author(s):  
Jing Jie Sha ◽  
Wei Si ◽  
Yin Zhang ◽  
Yun Fei Chen
Keyword(s):  
Concentration Gradient ◽  
Electrical Potential ◽  
Ionic Currents ◽  
Fixed Time ◽  
Controlled Delivery ◽  
Glass Capillary ◽  
Ion Conductance ◽  
Duration Time ◽  
In Trans ◽  
Pass Through

As the single molecules detection tool, nanopore is applied in more and more fields, such as medicine controlled delivery, ion conductance microscopes, nanosensors and DNA sequencing. When molecules pass through a nanopore, they will physically block the pore and produce measurable changes in ionic currents under an external electrical potential. Based on analyzing the resultant electrical signals, it is possible to detect various bio-molecules.Generally, the capturing ratio of nanopre for molecules is dependent on the intensity of electrical potential, to which the duration time of event is inversely proportional. It is difficult to analyze the too short duration time. Therefore, we investigate the study on concentration gradient of ionic solution effect on the capturing ratio of nanopore for DNA, which is in order to get the higher capturing ratio with the invariant duration time.In the experiments, we add different concentration solution in trans and cis parts of naopore separately to form the concentration gradient. We use three different types nanopore (α-hemolysin nanopore, Si3N4 membrane nanopore, glass capillary nanopore) to compare and get the similar results. The events of DNA translocating through nanopore are observed more compressed during the fixed time under the higher concentration gradient and there is no change to the duration time of DNA passing through the nanopore. It is demonstrated that concentration gradient could increase the capturing ratio of nanopore for DNA.

scholarly journals Importance of experimental information (metadata) for archived sequence data: case of specific gene bias due to lag time between sample harvest and RNA protection in RNA sequencing

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11875
Author(s):  
Tomoko Matsuda
Keyword(s):  
Gene Expression ◽  
Rna Sequencing ◽  
Time Course ◽  
Sequence Data ◽  
Specific Gene ◽  
Time Interval ◽  
Short Time Interval ◽  
Rna Seq ◽  
Lysis Buffer ◽  
Rna Protection

Large volumes of high-throughput sequencing data have been submitted to the Sequencing Read Archive (SRA). The lack of experimental metadata associated with the data makes reuse and understanding data quality very difficult. In the case of RNA sequencing (RNA-Seq), which reveals the presence and quantity of RNA in a biological sample at any moment, it is necessary to consider that gene expression responds over a short time interval (several seconds to a few minutes) in many organisms. Therefore, to isolate RNA that accurately reflects the transcriptome at the point of harvest, raw biological samples should be processed by freezing in liquid nitrogen, immersing in RNA stabilization reagent or lysing and homogenizing in RNA lysis buffer containing guanidine thiocyanate as soon as possible. As the number of samples handled simultaneously increases, the time until the RNA is protected can increase. Here, to evaluate the effect of different lag times in RNA protection on RNA-Seq data, we harvested CHO-S cells after 3, 5, 6, and 7 days of cultivation, added RNA lysis buffer in a time course of 15, 30, 45, and 60 min after harvest, and conducted RNA-Seq. These RNA samples showed high RNA integrity number (RIN) values indicating non-degraded RNA, and sequence data from libraries prepared with these RNA samples was of high quality according to FastQC. We observed that, at the same cultivation day, global trends of gene expression were similar across the time course of addition of RNA lysis buffer; however, the expression of some genes was significantly different between the time-course samples of the same cultivation day; most of these differentially expressed genes were related to apoptosis. We conclude that the time lag between sample harvest and RNA protection influences gene expression of specific genes. It is, therefore, necessary to know not only RIN values of RNA and the quality of the sequence data but also how the experiment was performed when acquiring RNA-Seq data from the database.

Shear-induced interaction of platelets with von Willebrand factor results in glycoprotein Ibα shedding

2009 ◽  
Vol 297 (6) ◽  
pp. H2128-H2135 ◽  
Author(s):  
Hong Cheng ◽  
Rong Yan ◽  
Suping Li ◽  
Yanhong Yuan ◽  
Jun Liu ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Kinase Inhibitor ◽  
Plaque Rupture ◽  
Thrombus Formation ◽  
Small Mass ◽  
Ectodomain Shedding ◽  
Glass Capillary ◽  
Time Duration ◽  
Von Willebrand ◽  
Willebrand Factor

Shear-induced platelet adhesion through the interaction of glycoprotein (GP) Ibα with von Willebrand factor (VWF) exposed at the injured vessel wall or atherosclerotic plaque rupture is a prerequisite for the physiological hemostatic process or pathological thrombus formation in stenosed arteries. Here we show that shear-induced interaction of platelets with immobilized VWF results in GPIbα ectodomain shedding. Washed platelets were exposed to VWF-coated glass capillary or cone-and-plate viscometer at different shear rates, and GPIbα ectodomain was shed from platelets, while a small mass of GPIbα COOH-terminal peptide, ∼17 kDa, was increased correspondingly. The extent of GPIbα shedding was enhanced with the concentration of immobilized VWF and the time duration of constant shear stress, whereas it was obviously reduced with the decreased number of adherent platelets. Pretreatment of platelets with membrane-permeable calpain inhibitors and metalloproteinase inhibitor abolished shear-induced GPIbα shedding. Furthermore, GPIbα shedding was obviously diminished by anti-integrin-αIIbβ3monoclonal antibody SZ21, phosphatidylinositol 3-kinase inhibitor wortmannin, and cell-permeable calcium chelator 1,2-bis( o-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid. These results indicate that shear-induced platelet-VWF interaction results in calpain and metalloproteinase-dependent GPIbα ectodomain shedding. These findings not only have a physiological implication in understanding the presence of glycocalicin in normal circulation, but also suggest a novel mechanism for the negative regulation of platelet function and the limitation of platelet thrombus infinite formation under pathophysiological flow conditions.

scholarly journals Time Course Based Artifact Identification for Independent Components of Resting-State fMRI

2013 ◽  
Vol 7 ◽  
Author(s):  
Christian Rummel ◽  
Rajeev Kumar Verma ◽  
Veronika Schöpf ◽  
Eugenio Abela ◽  
Martinus Hauf ◽  
...  
Keyword(s):  
Resting State ◽  
Time Course ◽  
Resting State Fmri ◽  
Independent Components ◽  
Artifact Identification

Time course of ureteral changes with obstruction

1976 ◽  
Vol 231 (2) ◽  
pp. 393-398 ◽  
Author(s):  
P Biancani ◽  
MP Zabinski ◽  
RM Weiss
Keyword(s):  
Tensile Stress ◽  
Time Course ◽  
Intraluminal Pressure ◽  
Time Interval ◽  
Wall Tension ◽  
Resting Pressure ◽  
Ureteral Dilatation

Chronic obstruction is characterized by a marked degree of ureteral dilatation and tortuosity which develops in the presence of a relatively low intraluminal pressure. To define the mechanism for the development of this relationship, the pressure-tension-deformation relationships of acute and chronically obstructed ureters were investigated. Rabbit ureters, in vivo, were obstructed and deformation correlated with intraluminal pressure. During the initial 3 h of obstruction, ureteral resting pressure increased from approximately 0 to 42 cm H2O, and diameter increased 16% with a slight increase in length. Subsequently, average wall tension (tensile stress) and intraluminal pressure declined, although deformation persisted. Between 6 h and 8 days after the onset of obstruction, intraluminal pressure remained essentially unchanged. During this time interval, ureteral deformation continued gradually and progressively as the ureter underwent creep both circumferentially and longitudinally. This was associated with a marked increase in average wall tension. At 8 days the diameter had increased by 170% and the length by 25%.

Observation and Numerical Simulation of Propagation of ULF Waves From the Ion Foreshock Into the Magnetosphere

2020 ◽  
Author(s):  
Kazue Takahashi ◽  
Turc Turc ◽  
Emilia Kilpua ◽  
Naoko Takahashi ◽  
Andrew Dimmock ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Ion Beam ◽  
Ulf Waves ◽  
Time Interval ◽  
Multiple Sources ◽  
Outer Magnetosphere ◽  
Magnetic Field Magnitude ◽  
Quantitative Understanding ◽  
Pass Through ◽  
The Waves

<p>Observational studies have demonstrated that ULF waves excited in the ion foreshock are a main source of Pc3-4 ULF waves detected in the magnetosphere. However, quantitative understanding of the propagation of the waves is not easy, because the waves are generated through a kinetic process in the foreshock, pass through the turbulent magnetosheath, and propagate as fast mode waves and couple to shear Alfven waves within the magnetosphere.  Recent advancement of hybrid numerical simulations of foreshock dynamics motivated us to analyze observational data from multiple sources and compare the results with simulation results. We have selected the time interval 1000-1200 UT on 20 July 2016, when the THEMIS, GOES, and Van Allen Probe spacecraft covered the solar wind, foreshock, magnetosheath, and magnetosphere. The EMMA magnetometers (L=1.6-6.5) were located near noon. We found that the spectrum of the magnetic field magnitude (Bt) in the foreshock exhibits a peak near 90 mHz, which agrees with the theoretical prediction assuming an ion beam instability in the foreshock.  A similar Bt spectrum is found in the dayside outer magnetosphere but not in the magnetosheath or in the nightside magnetosphere.  On the ground, a 90 mHz spectral peak was detected in the H component only at L=2-3. The numerical simulation using the VLASIATOR code shows that the foreshock is formed on the prenoon sector but that the effect of the upstream waves in the magnetosphere is most pronounced at noon. The Bt spectrum of the simulated waves in the outer magnetosphere exhibits a peak at 90 mHz, which is consistent with the observation.</p>

scholarly journals Assembly and suppression of endogenous Kv1.3 channels in human T cells.

1996 ◽  
Vol 107 (3) ◽  
pp. 409-420 ◽  
Author(s):  
G Panyi ◽  
C Deutsch
Keyword(s):  
Binomial Distribution ◽  
Time Course ◽  
K Channel ◽  
Time Interval ◽  
Transmembrane Segments ◽  
Human T Cells ◽  
Subunit Expression ◽  
Human T Lymphocyte ◽  
A Cell ◽  
Lymphocyte Cell

The predominant K+ channel in human T lymphocytes is Kv1.3, which inactivates by a C-type mechanism. To study assembly of these tetrameric channels in Jurkat, a human T-lymphocyte cell line, we have characterized the formation of heterotetrameric channels between endogenous wild-type (WT) Kv1.3 subunits and heterologously expressed mutant (A413V) Kv1.3 subunits. We use a kinetic analysis of C-type inactivation of currents produced by homotetrameric channels and heterotetrameric channels to determine the distribution of channels with different subunit stoichiometries. The distributions are well-described by either a binomial distribution or a binomial distribution plus a fraction of WT homotetramers, indicating that subunit assembly is a random process and that tetramers expressed in the plasma membrane do not dissociate and reassemble. Additionally, endogenous Kv1.3 current is suppressed by a heterologously expressed truncated Kv1.3 that contains the amino terminus and the first two transmembrane segments. The time course for suppression, which is maximal at 48 h after transfection, overlaps with the time interval for heterotetramer formation between heterologously expressed A413V and endogenous WT channels. Our findings suggest that diversity of K+ channel subtypes in a cell is regulated not by spatial segregation of monomeric pools, but rather by the degree of temporal overlap and the kinetics of subunit expression.

scholarly journals Modelling and Simulation of Cooperative Control for Bus Rapid Transit Vehicle Platoon in a Connected Vehicle Environment

2017 ◽  
Vol 29 (1) ◽  
pp. 67-75 ◽  
Author(s):  
Jiahui Liu ◽  
Peiqun Lin ◽  
Jing(Peter) Jin
Keyword(s):  
Cooperative Control ◽  
Control Model ◽  
Bus Rapid Transit ◽  
Time Interval ◽  
Connected Vehicle ◽  
Rapid Transit ◽  
Vehicle Platoon ◽  
Connected Vehicle Technology ◽  
Pass Through ◽  
Set Up

The aim of this paper is to develop a cooperative control model for improving the operational efficiency of Bus Rapid Transit (BRT) vehicles. The model takes advantage of the emerging connected vehicle technology. A connected vehicle centre is established to assign a specific reservation time interval and transmit the corresponding dynamic speed guidance to each BRT vehicle. Furthermore, a set of constraints have been set up to avoid bus queuing and waiting phenomena in downstream BRT stations. Therefore, many BRT vehicles are strategically guided to form a platoon, which can pass through an intersection with no impedance. An actual signalized intersection along the Guangzhou BRT corridor is employed to verify and assess the cooperative control model in various traffic conditions. The simulation-based evaluation results demonstrate that the proposed approach can reduce delays, decrease the number of stops, and improve the sustainability of the BRT vehicles.

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