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Symbolic dynamics is a useful tool in several fields of complexity analysis in nonlinear science. In order to investigate complexities of the human brain electrical activities under different brain functional states, a novel method in terms of symbolic entropy is defined and proposed in this paper. The novel algorithm based on symbolic dynamics is developed for quantitatively measuring the complexity...
The prevalence of atrial conduction defects and sinus node dysfunction increases with age. These age-related changes may play a critical role in establishing the substrate for the development of atrial fibrillation (AF), the most common sustained arrhythmia. Despite the association between atrial arrhythmias and age, little is known of the mechanisms that underlie changes in atrial electrophysiological...
The aims of the present study were to examine the effect of heptanol on electrical coupling during ischemia, and to assess whether changes in electrical coupling by heptanol is associated with its cardiac protection. Perfused isolated rat hearts were subjected to a 24 min infusion of heptanol (0.05, 0.1, 0.5 or 1.0 mmol/L) followed by 70 min of global no-flow ischemia or by 20 min of regional ischemia...
Two series of experiments were performed in the perfused isolated rat heart to determine whether stimulation of kappa-opioid receptor with U50,488H, a selective kappa-opioid receptor agonist, produces any changes in electrical coupling during prolonged ischemia and whether these changes in electrical coupling is associated with the cardioprotection induced by U50,488H. It was found that U50,488H concentration...
We have developed a computational model for the rat cardiac ventricular cell by using electrophysiology data. Our control model (Pandit et al., 2001). The model represents the bioelectric activity in the left ventricular cells in adult male rats. We have described the differences in the membrane properties within the left ventricle to simulate the action potential variations of the endocardial and...
In this study, we investigate the role of sinoatrial node (SAN) cellular heterogeneity in normal cardiac pacemaker function. Using detailed ionic models of electrical activity in SAN and atrial myocytes, we have formulated a number of models of SAN heterogeneity based on discrete-region (in which central and peripheral SAN type cell are separated into discrete regions), gradient and mosaic models...
Impulse oscillometry (IOS) is an innovative patient-friendly pulmonary testing technique which measures the respiratory system impedance (Z) by using the spectral components of pressure to flow ratio which yields resistance and reactance values at different frequencies. The high dimensionality of IOS measurement data makes the analysis of this information difficult. Artificial neural networks (ANNs)...
Methods have been developed for modeling cardiac activation which accounts for detailed myocardial geometric structures derived from specific tissue samples. This modeling allows both study and analysis of the effects of cleavage planes and other structural barriers to myocardial current flow. Specialized numerical and computational procedures have been developed to enable this modeling. The results...
We present a novel numerical scheme to accurately and efficiently simulate the spatiotemporal electrical propagation for three dimensional heart model. A meshfree particle representation of myocardial volume is first developed, upon which the electrical propagation can be obtained using the element-free Galerkin (EFG) method for the FitzHugh-Nagumo model. This method is based on a sufficient amount...
This article presents an analysis of the information rate of neural spike trains in an auditory nerve fiber (ANF) model stimulated extracellularly by sinusoidal electric stimuli under the case where a high-rate pulsatile waveform is presented as a conditioner for increasing the across-fiber-independency, i.e., desynchronization. In the computer simulation, stimulus current waveforms were presented...
Based on Poisson variability, the strength of cross-correlation of two spike trains was quantified by a cross-correlation index (CCI). Discriminant analysis with CCI was used to quantify the contribution of cross-correlation in stimulus feature discrimination in an ensemble of retinal ganglion cells. Compared with simulated Poisson cell pair, it was found that cross-correlation carried useful information...
The self-assembling of DNA and cationic polymers are of interest for their biological applications. In this paper, the interaction of DNA with PAMAM was studied by agarose gel electrophoresis, size and zeta-potential measurements and circular dichroism (CD) spectroscopy. DNA was shown to form stable complexes with PAMAM by gel electrophoresis. The mean particle size of the complexes was in the range...
Nano-structured four branched, blocked star vector (BSV) was molecularly designed by iniferter-based photo-living radical copolymerization method of N,N-dimethylaminopropylacrylamide and then N,N-dimethylacrylamide from four dithiocarbamate-derivatized benzene for a novel gene delivery non-viral vector. The conjugated pDNA complexes were satisfactorily stable in the condition of the electrophoresis...
We developed a new electroporation system, including a microchip and a logic circuit, and combining with the function of electrophoresis, which can site-specific enhancement of the gene concentration. We have demonstrated that the electroporation microchip could enhance and target in vitro gene transfection for cell lines. In this micro-device, the outer electrodes could provide the electrophoresis...
Bone mass loss caused by microgravity is considered as one of the worst influences to human body during long-term spaceflight. As one of the countermeasures to retain bone mass, muscle electrical stimulation is just started in spaceflight application and needs further research. This work is aimed to investigate the effects of muscle electrical stimulation based on the tail-suspended rat experiment...
Wave propagation through the arterial system changes with age and disease state, and mutant mice are often used to study these conditions. We have developed several noninvasive ultrasonic techniques to measure blood velocity and vessel wall motion from which we can calculate aortic pulse wave velocity (PWV), local compliance, impedance spectra, characteristic impedance (Zc), augmentation index (AI),...
Dwarf mouse (deficient in growth hormone and insulin-like growth factor-1) lives about 30% longer than wild type mice. However, very little is known about their cardiovascular physiology. We examined the aortic input impedance in dwarf mice and their wild-type littermates to evaluate any differences. Aortic impedance was determined using pressure and velocity signals which are independent of body...
For the gentle and non-destructive characterisation of small tissue samples, non-invasive methods are required for biotechnological applications and medical diagnostics. One approach is the characterisation of small tissue samples by impedance spectroscopy using a measuring capillary. In this paper, the applicability of a capillary measuring system to record the impedance of a biological sample over...
This is a review of the state of the art in two important modalities thermal and electrical properties of living tissues - that are complementary from the point of view of medical diagnostics. Advantages and limitations of IR thermal imaging and electroimpedance measurements, including tomography procedures are discussed. Properties of both modalities are compared from the point of view of skin burn...
Previous studies in various animal models have shown that respiratory premotor and motor neurons undergo rapid changes in biochemical and bioelectric properties during the first month of postnatal life. Early in postnatal life, there is an increase in the complexity of the morphology of the dendritic tree of respiratory neurons as it changes from a bipolar to a multipolar morphology. During normal...
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