scholarly journals Occurrence of Calcium Oscillations in Human Spermatozoa Is Based on Spatial Signaling Enzymes Distribution

2021 ◽  
Vol 22 (15) ◽  
pp. 8018
Author(s):  
Julia Korobkin ◽  
Fedor A. Balabin ◽  
Sergey A. Yakovenko ◽  
Ekaterina Yu. Simonenko ◽  
Anastasia N. Sveshnikova
Keyword(s):  
Calcium Signaling ◽  
Computational Models ◽  
Fluorescent Microscopy ◽  
Three Dimensional ◽  
Low Frequency ◽  
Calcium Oscillations ◽  
Qualitative Description ◽  
Human Spermatozoa ◽  
Three Dimensional Model ◽  
Low Frequency Oscillations

In human spermatozoa, calcium dynamics control most of fertilization events. Progesterone, present in the female reproductive system, can trigger several types of calcium responses, such as low-frequency oscillations. Here we aimed to identify the mechanisms of progesterone-induced calcium signaling in human spermatozoa. Progesterone-induced activation of fluorophore-loaded spermatozoa was studied by fluorescent microscopy. Two computational models were developed to describe the spermatozoa calcium responses: a homogeneous one based on a system of ordinary differential equations and a three-dimensional one with added space dimensions and diffusion for the cytosolic species. In response to progesterone, three types of calcium responses were observed in human spermatozoa: a single transient rise of calcium concentration in cytosol, a steady elevation, or low-frequency oscillations. The homogenous model provided qualitative description of the oscillatory and the single spike responses, while the three-dimensional model captured the calcium peak shape and the frequency of calcium oscillations. The model analysis demonstrated that an increase in the calcium diffusion coefficient resulted in the disappearance of the calcium oscillations. Additionally, in silico analysis suggested that the spatial distribution of calcium signaling enzymes governs the appearance of calcium oscillations in progesterone-activated human spermatozoa.

Experimental and biological variation of three-dimensional transcranial Doppler measurements

1993 ◽  
Vol 75 (6) ◽  
pp. 2805-2810 ◽  
Author(s):  
L. L. Thomsen ◽  
H. K. Iversen
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Transcranial Doppler ◽  
Coefficient Of Variation ◽  
Cerebral Arteries ◽  
Three Dimensional ◽  
Low Frequency ◽  
Control Groups ◽  
Mean Velocity ◽  
Low Frequency Oscillations

A new transcranial Doppler system (3-D Transscan, Eden Medizinische Elektronik) was evaluated in relation to sex, age, intersubject, interobserver, side-to-side, and day-to-day variation. Fifty-eight healthy volunteers participated (aged 18–80 yr). Mean velocity was higher in females than in males and decreased with age. The coefficient of variation in the middle cerebral artery was 26% between subjects, 20% between sides, 16% between days, 13% between observers, and 7% during 5 min. The coefficient of variation was higher in the anterior and posterior cerebral arteries. Bruits were heard in 35 subjects, 24 females and 11 males (P = 0.002). When middle cerebral artery velocity was monitored, high- and low-frequency oscillations were found, with a mean frequency of 5 and 1.6/min, respectively. These variations underline the necessity of standardized conditions and very carefully matched control groups in studies using transcranial Doppler. This is especially important when expected changes are small and easy to overlook, as in studies of normal physiological responses and migraine.

scholarly journals Effects of Ultrastructural Remodeling on Calcium Signaling and Electrophysiology in a Three-Dimensional Model of the Human Atrial Myocyte

2020 ◽  
Vol 118 (3) ◽  
pp. 256a
Author(s):  
Xianwei Zhang ◽  
Haibo Ni ◽  
Stefano Morotti ◽  
William E. Louch ◽  
Andrew G. Edwards ◽  
...  
Keyword(s):  
Calcium Signaling ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Atrial Myocyte ◽  
Human Atrial Myocyte

Parameter Estimation of Nonlinear Biomedical Systems Using Extended Kalman Filter Algorithm

2017 ◽  
pp. 76-99 ◽  
Author(s):  
Kamalanand Krishnamurthy
Keyword(s):  
Parameter Estimation ◽  
Kalman Filter ◽  
Extended Kalman Filter ◽  
Computational Models ◽  
Three Dimensional ◽  
Model Parameters ◽  
State Variables ◽  
Three Dimensional Model ◽  
Biomedical Systems ◽  
Estimation Of Model Parameters

Parameter estimation is a central issue in mathematical modelling of biomedical systems and for the development of patient specific models. The technique of estimating parameters helps in obtaining diagnostic information from computational models of biological systems. However, in most of the biomedical systems, the estimation of model parameters is a challenging task due to the nonlinearity of mathematical models. In this chapter, the method of estimation of nonlinear model parameters from measurements of state variables, using the extended Kalman filter, is extensively explained using an example of the three-dimensional model of the HIV/AIDS system.

Parameter Estimation of Nonlinear Biomedical Systems Using Extended Kalman Filter Algorithm

2018 ◽  
pp. 690-713
Author(s):  
Kamalanand Krishnamurthy
Keyword(s):  
Parameter Estimation ◽  
Kalman Filter ◽  
Extended Kalman Filter ◽  
Computational Models ◽  
Three Dimensional ◽  
Model Parameters ◽  
State Variables ◽  
Three Dimensional Model ◽  
Biomedical Systems ◽  
Estimation Of Model Parameters

Parameter estimation is a central issue in mathematical modelling of biomedical systems and for the development of patient specific models. The technique of estimating parameters helps in obtaining diagnostic information from computational models of biological systems. However, in most of the biomedical systems, the estimation of model parameters is a challenging task due to the nonlinearity of mathematical models. In this chapter, the method of estimation of nonlinear model parameters from measurements of state variables, using the extended Kalman filter, is extensively explained using an example of the three-dimensional model of the HIV/AIDS system.

scholarly journals Effects of Varying Transverse and Axial Tubules in a Three-Dimensional Model of Calcium Signaling in the Human Atrial Myocyte

2019 ◽  
Vol 116 (3) ◽  
pp. 231a-232a
Author(s):  
Xianwei Zhang ◽  
Haibo Ni ◽  
Stefano Morotti ◽  
Daisuke Sato ◽  
Eleonora Grandi
Keyword(s):  
Calcium Signaling ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Atrial Myocyte ◽  
Human Atrial Myocyte

scholarly journals Cross-field transport due to low-frequency oscillations in the auroral region: A three-dimensional simulation

1999 ◽  
Vol 104 (A3) ◽  
pp. 4297-4304 ◽  
Author(s):  
Supriya B. Ganguli ◽  
Parvez N. Guzdar ◽  
Valeriy V. Gavrishchaka ◽  
Warren A. Krueger ◽  
Paul E. Blanchard
Keyword(s):  
Three Dimensional ◽  
Low Frequency ◽  
Auroral Region ◽  
Low Frequency Oscillations ◽  
Dimensional Simulation

scholarly journals A Simplified 3D Oceanic Model Assimilating Geostrophic Currents: Application to the POMME Experiment

2005 ◽  
Vol 35 (5) ◽  
pp. 628-644 ◽  
Author(s):  
Hervé Giordani ◽  
Guy Caniaux ◽  
Louis Prieur
Keyword(s):  
Ocean Circulation ◽  
Three Dimensional ◽  
Low Frequency ◽  
Vertical Motion ◽  
Momentum Equation ◽  
Altimeter Data ◽  
Three Dimensional Model ◽  
Geostrophic Currents ◽  
Quasigeostrophic Model ◽  
Oceanic Model

Abstract A simplified oceanic model is developed to easily perform cheap and realistic mesoscale simulations on an annual scale. This simplified three-dimensional oceanic model is obtained by degenerating the primitive equations system by prescribing continuously analysis-derived geostrophic currents Ug into the momentum equation in substitution of the horizontal pressure gradient. Simplification is provided by a time sequence of Ug called guide, which is used as a low-resolution and low-frequency interpolator. This model is thus necessarily coupled to systems providing geostrophic currents—that is, ocean circulation models, analyzed/reanalyzed fields, or climatologies. In this model, the mass and currents fields are constrained to adjust to the geostrophic guide at all scales. The vertical velocity is deduced from the vorticity equation, which ensures the coherence between the vertical motion and the geostrophic structures evolution. Horizontal and vertical advection are the coupling processes that can be activated independently from each other and offer the possibility to (i) continuously derive a three-dimensional model when all processes are activated, (ii) understand how some retroaction loops are generated, and (iii) study development of structures as a function of the geostrophic environment. The model was tested during a 50-day lasting simulation over the Program Océan Multidisciplinaire Méso Echelle (POMME) experiment (northeast Atlantic Ocean, September 2000–October 2001). Optimal analyzed geostrophic currents were derived weekly during POMME from a quasigeostrophic model assimilating altimeter data. Comparison with independent in situ and satellite data indicates that this simulation is very realistic and does not drift, thanks to the prescribed geostrophic guide.

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