scholarly journals A protocol combining current- and voltage-clamp provides a novel and useful three-dimensional representation of cardiac action potential

2014 ◽  
Vol 87 (1) ◽  
Author(s):  
Massimiliano Zaniboni ◽  
Francesca Cacciani
Keyword(s):  
Action Potential ◽  
Current Source ◽  
Three Dimensional ◽  
Membrane Conductance ◽  
Ventricular Repolarization ◽  
Cardiac Action Potential ◽  
Dimensional Representation ◽  
Cardiac Action ◽  
Three Dimensional Representation

A compact three-dimensional representation of cardiac action potential (AP) properties in terms of current source is presented here. The experimental protocol used to obtain such representation is based on the measure of instantaneous current-voltage relationships during the course of the AP. The procedure, which combines current- and voltage-clamps on patch clamped cardiac myocytes, has been previously applied to real cells, and then extended to computer simulations with cellular ventricular AP models. The three-dimensional AP representation allows to easily estimate membrane resistance during repolarization, a key factor for the modulation of ventricular repolarization. It also shows that, during late ventricular repolarization, membrane conductance becomes negative, <em>i.e.</em> repolarization is auto-regenerative. The novel AP representation is therefore a useful tool for both in vivo and in silico cardiac cellular electrophysiological investigations.

Restitution and adaptation measurements for the estimate of short-term cardiac action potential memory: comparison of five human ventricular models

EP Europace ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 1594-1602
Author(s):  
Massimiliano Zaniboni ◽  
Francesca Cacciani
Keyword(s):  
Steady State ◽  
Action Potential ◽  
Short Term Memory ◽  
Computational Study ◽  
Numerical Models ◽  
Cardiac Action Potential ◽  
Short Term ◽  
Term Memory ◽  
Cardiac Action

Abstract Aims This computational study refines our recently published pacing protocol to measure short-term memory (STM) of cardiac action potential (AP), and apply it to five numerical models of human ventricular AP. Methods and results Several formulations of electrical restitution (ER) have been provided over the years, including standard, beat-to-beat, dynamic, steady-state, which make it difficult to compare results from different studies. We discuss here the notion of dynamic ER (dER) by relating it to its steady-state counterpart, and propose a pacing protocol based on dER to measure STM under periodically varying pacing cycle length (CL). Under high and highly variable-pacing rate, all models develop STM, which can be measured over the entire sequence by means of dER. Short-term memory can also be measured on a beat-to-beat basis by estimating action potential duration (APD) adaptation after clamping CL constant. We visualize STM as a phase shift between action potential (AP) parameters over consecutive cycles of CL oscillations, and show that delay between CL and APD oscillation is nearly constant (around 92 ms) in the five models, despite variability in their intrinsic AP properties. Conclusion dER, as we define it and together with other approaches described in the study, provides an univocal way to measure STM under extreme cardiac pacing conditions. Given the relevance of AP memory for repolarization dynamics and stability, STM should be considered, among other usual biomarkers, to validate and tune cardiac AP models. The possibility of extending the method to in vivo cellular and whole organ models can also be profitably explored.

scholarly journals An Optical Mapping of Cardiac Action Potential on the Three-Dimensional Surface Model of a Heart

2004 ◽  
Vol 16 (Supplement) ◽  
pp. 221-222
Author(s):  
Shiho Nashimoto ◽  
Yuhei Takata ◽  
Takahiro Yamaguchi ◽  
Tatsuhiko Arafune ◽  
Etsuko Kobayashi ◽  
...  
Keyword(s):  
Action Potential ◽  
Optical Mapping ◽  
Three Dimensional ◽  
Cardiac Action Potential ◽  
Surface Model ◽  
Cardiac Action ◽  
Dimensional Surface

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

scholarly journals Structured-light 3D scanning of exhibited historical clothing—a first-ever methodical trial and its results

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Jerzy Montusiewicz ◽  
Marek Miłosz ◽  
Jacek Kęsik ◽  
Kamil Żyła
Keyword(s):  
Cultural Heritage ◽  
Information Technologies ◽  
Structured Light ◽  
Three Dimensional ◽  
3D Models ◽  
3D Scanning ◽  
Dimensional Representation ◽  
3D Scanner ◽  
Three Dimensional Representation ◽  
3D Scanners

AbstractHistorical costumes are part of cultural heritage. Unlike architectural monuments, they are very fragile, which exacerbates the problems of their protection and popularisation. A big help in this can be the digitisation of their appearance, preferably using modern techniques of three-dimensional representation (3D). The article presents the results of the search for examples and methodologies of implementing 3D scanning of exhibited historical clothes as well as the attendant problems. From a review of scientific literature it turns out that so far practically no one in the world has made any methodical attempts at scanning historical clothes using structured-light 3D scanners (SLS) and developing an appropriate methodology. The vast majority of methods for creating 3D models of clothes used photogrammetry and 3D modelling software. Therefore, an innovative approach was proposed to the problem of creating 3D models of exhibited historical clothes through their digitalisation by means of a 3D scanner using structural light technology. A proposal for the methodology of this process and concrete examples of its implementation and results are presented. The problems related to the scanning of 3D historical clothes are also described, as well as a proposal how to solve them or minimise their impact. The implementation of the methodology is presented on the example of scanning elements of the Emir of Bukhara's costume (Uzbekistan) from the end of the nineteenth century, consisting of the gown, turban and shoes. Moreover, the way of using 3D models and information technologies to popularise cultural heritage in the space of digital resources is also discussed.

Sign in / Sign up

Export Citation Format

Share Document