The Gurvich waveform has lower defibrillation threshold than the rectilinear waveform and the truncated exponential waveform in the rabbit heart

2005 ◽  
Vol 83 (2) ◽  
pp. 152-160 ◽  
Author(s):  
Fujian Qu ◽  
Fidel Zarubin ◽  
Brian Wollenzier ◽  
Vladimir P Nikolski ◽  
Igor R Efimov
Keyword(s):  
Action Potentials ◽  
Cellular Response ◽  
Rabbit Heart ◽  
Defibrillation Threshold ◽  
Biphasic Waveform ◽  
Transmembrane Action Potentials ◽  
Vitro Model ◽  
Response Transfer ◽  
External Defibrillator

Implantable cardioverter defibrillator studies have established the superiority of biphasic waveforms over monophasic waveforms. However, external defibrillator studies of biphasic waveforms are not as widespread. Our objective was to compare the defibrillation efficacy of clinically used biphasic waveforms, i.e., truncated exponential, rectilinear, and quasi-sinusoidal (Gurvich) waveforms in a fibrillating heart model. Langendorff-perfused rabbit hearts (n = 10) were stained with a voltage-sensitive fluorescent dye, Di-4-ANEPPS. Transmembrane action potentials were optically mapped from the anterior epicardium. We found that the Gurvich waveform was significantly superior (p < 0.05) to the rectilinear and truncated exponential waveforms. The defibrillation thresholds (mean ± SE) were as follows: Gurvich, 0.25 ± 0.01 J; rectilinear-1, 0.34 ± 0.01 J; rectilinear-2, 0.33 ± 0.01 J; and truncated exponential, 0.32 ± 0.02 J. Using optically recorded transmembrane responses, we determined the shock-response transfer function, which allowed us to predict the cellular response to waveforms at high accuracy. The passive parallel resistor-capacitor model (RC-model) predicted polarization superiority of the Gurvich waveform in the myocardium with a membrane time constant (τm) of less than 2 ms. The finding of a lower defibrillation threshold with the Gurvich waveform in an in vitro model of external defibrillation suggests that the Gurvich waveform may be important for future external defibrillator designs.Key words: defibrillation, optical mapping, biphasic waveform, Gurvich waveform.

Short-term effect of FSH on gene expression in bovine granulosa cells in vitro

2018 ◽  
Vol 30 (8) ◽  
pp. 1154 ◽  
Author(s):  
Anne-Laure Nivet ◽  
Isabelle Dufort ◽  
Isabelle Gilbert ◽  
Marc-André Sirard
Keyword(s):  
Gene Expression ◽  
Cellular Response ◽  
Epithelial To Mesenchymal Transition ◽  
Short Term ◽  
Mesenchymal Transition ◽  
Vitro Model ◽  
Cell Transcriptome ◽  
Physical Changes

In reproduction, FSH is one of the most important hormones, especially in females, because it controls the number of follicles and the rate of follicular growth. Although several studies have examined the follicular response at the transcriptome level, it is difficult to obtain a clear and complete picture of the genes responding to an increase in FSH in an in vivo context because follicles undergo rapid morphological and physical changes during their growth. To help define the transcriptome downstream response to FSH, an in vitro model was used in the present study to observe the short-term (4 h) cellular response. Gene expression analysis highlighted a set of novel transcripts that had not been reported previously as being part of the FSH response. Moreover, the results of the present study indicate that the epithelial to mesenchymal transition pathway is inhibited by short-term FSH stimuli, maintaining follicles in a growth phase and preventing differentiation. Modulating gene expression in vitro has physiological limitations, but it can help assess the potential downstream response and begin the mapping of the granulosa cell transcriptome in relation to FSH. This information is a key feature to help discriminate between the effects of FSH and LH, or to elucidate the overlapping of insulin-like growth factor 1 and FSH in the granulosa mitogenic response.

GENERATION OF RECTANGULAR BIPHASIC WAVEFORM TO DECREASE DEFIBRILLATION THRESHOLD FOR EXTERNAL DEFIBRILLATOR

2012 ◽  
Vol 24 (05) ◽  
pp. 395-401
Author(s):  
Ayoub Kavousi ◽  
Valiallah Saba
Keyword(s):  
Prototype Model ◽  
Second Phase ◽  
Defibrillation Threshold ◽  
Peak Current ◽  
A Value ◽  
Current Path ◽  
Biphasic Waveform ◽  
In Series ◽  
Duration Relationship ◽  
External Defibrillator

Studies have shown that defibrillation threshold for current amplitude of biphasic truncated exponential (BTE) waveform has a hyperbolic strength–duration relationship. Theoretical and experimental results have shown that decreasing the tilt of BTE waveforms decreases the defibrillation threshold. On the other hand, low peak current waveform reduces probability of myocardium damage and burn. Therefore, achieving a waveform with low tilt and low peak current is desired. All DC defibrillators use a capacitor to store and deliver required energy. Because of capacitor discharging nature, the tilt of waveforms is high. In rectilinear biphasic waveform (RBW), which was generated by ZOLL M-series defibrillator, the tilt of the first phase was decreased using an adjustable resistor connected in series with current path. But the defibrillator cannot keep the current constant in the second phase and in the both phases for high transthoracic impedances (TTI) either. In this paper, for solving these problems, a circuit that generates rectangular biphasic waveform is designed. In this circuit, five resistors are used and connected in series. Then an IGBT switch is connected to each resistor in parallel. Also, control of minimum current ripple is applied in order to decide which resistors should be worked in each time. The circuit is simulated in MATLAB/Simulink and a prototype model is constructed. Results demonstrate that the tilt of the waveform is notably reduced to a value less than 10%.

scholarly journals DIGE Proteome Analysis Reveals Suitability of Ischemic Cardiac In Vitro Model for Studying Cellular Response to Acute Ischemia and Regeneration

PLoS ONE ◽  
2012 ◽  
Vol 7 (2) ◽  
pp. e31669 ◽  
Author(s):  
Sina Haas ◽  
Heinz-Georg Jahnke ◽  
Nora Moerbt ◽  
Martin von Bergen ◽  
Seyedhossein Aharinejad ◽  
...  
Keyword(s):  
Cellular Response ◽  
In Vitro Model ◽  
Proteome Analysis ◽  
Acute Ischemia ◽  
Vitro Model

scholarly journals Modelling biochemical gradients in vitro to control cell compartmentalization in a microengineered 3D model of the intestinal epithelium

2021 ◽  
Author(s):  
Gizem Altay ◽  
Aina Abad-Lazaro ◽  
Emilio Jose Gualda ◽  
Jordi Folch ◽  
Claudia Insa ◽  
...  
Keyword(s):  
Cellular Response ◽  
Control Cell ◽  
Mesh Size ◽  
Light Sheet ◽  
Differentiated Cells ◽  
Vitro Model ◽  
Cell Compartmentalization ◽  
Cellular Compartmentalization

Gradients of signaling pathways within the intestinal stem cell (ISC) niche are instrumental for cellular compartmentalization and tissue function, yet how are they formed and sensed by the epithelium is still not fully understood. Here we present a new in vitro model of the small intestine based on primary epithelial cells (i), apically accessible (ii), with native tissue mechanical properties and controlled mesh size (iii), 3D villus-like architecture (iv), and biomolecular gradients of the ISC niche (v). Biochemical gradients are formed through the hydrogel-based scaffolds by free diffusion from a source to a sink chamber. To confirm the establishment of precise spatiotemporally controlled gradients, we employ light-sheet fluorescence microscopy and in-silico modelling. The ISC niche biochemical gradients applied along the villus axis lead to the in vivo-like compartmentalization of the proliferative and differentiated cells, while changing the composition and concentration of the biochemical factors affects the cellular organization along the villus axis. This novel 3D in vitro intestinal model derived from organoids recapitulates both the villus-like architecture and the gradients of ISC biochemical factors, thus opening the possibility to study in vitro the nature of such gradients and the resulting cellular response.

scholarly journals Host Cellular Response to Multiple Stressors Using a Chicken in vitro Model

2016 ◽  
Author(s):  
Anna Slawinska ◽  
John C. F. Hsieh ◽  
Carl J. Schmidt ◽  
Susan J. Lamont
Keyword(s):  
Cellular Response ◽  
In Vitro Model ◽  
Multiple Stressors ◽  
Vitro Model

Effects Of Gelatine-Coated Vascular Grafts On Human Neutrophils

2015 ◽  
Vol 87 (9) ◽  
Author(s):  
Frank Meyer ◽  
Thomas Buerger ◽  
Zuhir Halloul ◽  
Hans Lippert ◽  
Brigitte König ◽  
...  
Keyword(s):  
Cellular Response ◽  
Healing Process ◽  
Vascular Grafts ◽  
Cell Interaction ◽  
Human Neutrophils ◽  
Prosthetic Material ◽  
Graft Material ◽  
Coated Materials ◽  
Vitro Model

Abstractwas to investigate the immune-modulatory potential of commercially available PTFE and polyester vascular grafts with and without gelatine-coating. The biomaterial-cell-interaction was characterized by changes of established parameters such as PMN-related receptors/mediators, phagocytosis potential and capacity as well as the effect of an additional plasma-dependent modulation.By means of a standardized experimental in vitro model, various vascular graft material (PTFE/polyester/uncoated/gelatine-coated) was used for incubation with or without plasma and co-culturing with human neutrophile granulocytes (PMN) followed by analysis of representative receptors and mediators (CD62L, CD11b, CXCR2, fMLP-R, IL-8, Elastase, LTBComparing the vascular grafts, un-coated PTFE induced the lowest magnitude of cell stimulation whereas in case of gelatine-coating, cell response exceeded those of the other vascular grafts. This was also found comparing the polyester-based prosthetic material. Gelatine-coated polyester led to a more pronounced release of elastase than gelatine-coated PTFE and the uncoated materials. The results of oxidative burst indicated a reduced phagocytosis capacity in case of gelatine-coated polyester. Plasma incubation did also provide an impact on the cellular response. While in case of gelatine-coating, PMN-related receptor stimulation became lower, it increased by native polyester. The latter one did also induce more mediators such as IL-8 and LTBThere have been no extensive data on cell-cell interactions, cytokines and general histo-/hemocompatibility of human cells by the new generation of vascular grafts. It remains still open whether healing process and infectious resistance can be compromised by material-dependent over-stimulation or reduced phagocytosis potential of the immune cells of the primary unspecific immune response induced by gelatine-coated materials.

An in vitro model for investigation of vitamin A effects on wound healing

2021 ◽  
pp. 1-6
Author(s):  
Hoda Keshmiri Neghab ◽  
Mohammad Hasan Soheilifar ◽  
Gholamreza Esmaeeli Djavid
Keyword(s):  
Wound Healing ◽  
Endothelial Cell ◽  
Vitamin A ◽  
In Vitro Model ◽  
Cellular Proliferation ◽  
Endothelial Cell Migration ◽  
Normal Fibroblast ◽  
Anti Inflammatory ◽  
Vitro Model

Abstract. Wound healing consists of a series of highly orderly overlapping processes characterized by hemostasis, inflammation, proliferation, and remodeling. Prolongation or interruption in each phase can lead to delayed wound healing or a non-healing chronic wound. Vitamin A is a crucial nutrient that is most beneficial for the health of the skin. The present study was undertaken to determine the effect of vitamin A on regeneration, angiogenesis, and inflammation characteristics in an in vitro model system during wound healing. For this purpose, mouse skin normal fibroblast (L929), human umbilical vein endothelial cell (HUVEC), and monocyte/macrophage-like cell line (RAW 264.7) were considered to evaluate proliferation, angiogenesis, and anti-inflammatory responses, respectively. Vitamin A (0.1–5 μM) increased cellular proliferation of L929 and HUVEC (p < 0.05). Similarly, it stimulated angiogenesis by promoting endothelial cell migration up to approximately 4 fold and interestingly tube formation up to 8.5 fold (p < 0.01). Furthermore, vitamin A treatment was shown to decrease the level of nitric oxide production in a dose-dependent effect (p < 0.05), exhibiting the anti-inflammatory property of vitamin A in accelerating wound healing. These results may reveal the therapeutic potential of vitamin A in diabetic wound healing by stimulating regeneration, angiogenesis, and anti-inflammation responses.

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