Monomer and Excimer Emission in a Conformational and Stacking-Adaptable Molecular System.

A design strategy that combines molecular conformation, alkyl chain length, and charge-transfer effects has been developed to obtain conformational and stacking-adaptable donor-acceptor-π type molecules for precisely regulating the monomer and excimer emission in a single luminous platform under different environments. These fluorophores can exhibit bright monomer emissions when they are in the dispersed state based on their planar conformation. However, when the luminous molecules with short alkyl side chains are in the crystalline state, their molecular conformation can become distorted, further inducing strong intermolecular interactions and staggered π-π stacking for bright excimer emission. More importantly, their dispersed and aggregated states can be reversibly regulated in a phase-change fatty acid matrix, to achieve temperature-responsive fluorescence for temperature monitoring and advanced information encryption.

Low-Level Vagus Nerve Stimulation Reverses Cardiac Dysfunction and Subcellular Calcium Handling in Rats With Post-Myocardial Infarction Heart Failure.

Vagus nerve stimulation (VNS), targeting the imbalanced autonomic nervous system, is a promising therapeutic approach for chronic heart failure (HF). Moreover, calcium cycling is an important part of cardiac excitation-contraction coupling (ECC), which also participates in the antiarrhythmic effects of VNS. We hypothesized that low-level VNS (LL-VNS) could improve cardiac function by regulation of intracellular calcium handling properties. The experimental HF model was established by ligation of the left anterior descending coronary artery (LAD). Thirty-two male Sprague-Dawley rats were divided into 3 groups as follows; control group (sham operated without coronary ligation, n = 10), HF-VNS group (HF rats with VNS, n = 12), and HF-SS group (HF rats with sham nerve stimulation, n = 10). After 8 weeks of treatment, LL-VNS significantly improved left ventricular ejection fraction (LVEF) and attenuated myocardial interstitial fibrosis in the HF-VNS group compared with the HF-SS group. Elevated plasma norepinephrine and dopamine, but not epinephrine, were partially reduced by LL-VNS. Additionally, LL-VNS restored the protein and mRNA levels of sarcoplasmic reticulum Ca(2+) ATPase (SERCA2a), Na(+)-Ca(2+) exchanger 1 (NCX1), and phospholamban (PLB) whereas the expression of ryanodine receptor 2 (RyR2) as well as mRNA level was unaffected. Thus, our study results suggest that the improvement of cardiac performance by LL-VNS is accompanied by the reversal of dysfunctional calcium handling properties including SERCA2a, NCX1, and PLB which may be a potential molecular mechanism of VNS for HF.

[Wearable Automatic External Defibrillators].

Defibrillation is the most effective method of treating ventricular fibrillation(VF), this paper introduces wearable automatic external defibrillators based on embedded system which includes EGG measurements, bioelectrical impedance measurement, discharge defibrillation module, which can automatic identify VF signal, biphasic exponential waveform defibrillation discharge. After verified by animal tests, the device can realize EGG acquisition and automatic identification. After identifying the ventricular fibrillation signal, it can automatic defibrillate to abort ventricular fibrillation and to realize the cardiac electrical cardioversion.

[A wireless implantable stimulating and ECG monitoring system for animal models of chronic atrial fibrillation].

The rapid atrial pacing model is one of the most popular atrial fibrillation animal models. In this paper, a novel implementation of wireless implantable stimulating and ECG monitoring system is described based on the requirements of rapid atrial pacing model. Hardware circuits and software structure of the system are introduced. And test outcomes through in-vitro simulation and in-vivo animal models are presented. After verified by animal tests, the system can be used to initiate and monitor chronic atrial fibriation in real time.

[An ultra-low power, wearable, long-term ECG monitoring system with mass storage].

In this paper, we described an ultra-low power, wearable ECG system capable of long term monitoring and mass storage. This system is based on micro-chip PIC18F27J13 with consideration of its high level of integration and low power consumption. The communication with the micro-SD card is achieved through SPI bus. Through the USB, it can be connected to the computer for replay and disease diagnosis. Given its low power cost, lithium cells are used to support continuous ECG acquiring and storage for up to 15 days. Meanwhile, the wearable electrodes avoid the pains and possible risks in implanting. Besides, the mini size of the system makes long wearing possible for patients and meets the needs of long-term dynamic monitoring and mass storage requirements.

Carbon nanotube-based self-adhesive polymer electrodes for wireless long-term recording of electrocardiogram signals.

In this study, the concept of polymer electrodes integrated with a wireless electrocardiogram (ECG) system was described. Polymer electrodes for long-term ECG measurements were fabricated by loading high content of carbon nanotubes (CNTs) in polydimethylsiloxane. Silver nanoparticles (Ag NPs) were added to increase the flexibility of the polymer and the conductivity of the electrode. An ECG electrode patch was fabricated by integrating the electrodes with an adhesive polydimethylsiloxane (aPDMS) layer. Holes in the electrode filled with aPDMS can enable robust contact between the electrode and skin, reducing motion artifacts. A wireless ECG measurement system was developed and adapted to the polymer electrodes. The polymer electrodes combined with the measurement system were successfully applied in wireless, long-term recording of ECG signals. An eleven-day continuous test showed that the ECG signal did not degrade over time. The results of attach/detach tests demonstrated that the ECG signal was affected by motion artifacts after six attach/detach cycles. The electrodes produced are flexible and exhibit good ECG performance, and therefore can be used in wearable medical monitoring systems. The approach proposed in this study holds significant promise for commercial application in medical fields.

A novel method of fabricating carbon nanotubes-polydimethylsiloxane composite electrodes for electrocardiography.

Polymer-based flexible electrodes are receiving much attention in medical applications due to their good wearing comfort. The current fabrication methods of such electrodes are not widely applied. In this study, polydimethylsiloxane (PDMS) and conductive additives of carbon nanotubes (CNTs) were employed to fabricate composite electrodes for electrocardiography (ECG). A three-step dispersion process consisting of ultrasonication, stirring, and in situ polymerization was developed to yield homogenous CNTs-PDMS mixtures. The CNTs-PDMS mixtures were used to fabricate CNTs-PDMS composite electrodes by replica technology. The influence of ultrasonication time and CNT concentration on polymer electrode performance was evaluated by impedance and ECG measurements. The signal amplitude of the electrodes prepared using an ultrasonication time of 12 h and CNT content of 5 wt% was comparable to that of commercial Ag/AgCl electrodes. The polymer electrodes were easily fabricated by conventional manufacturing techniques, indicating a potential advantage of reduced cost for mass production.

Effects of the Galanin Receptor Antagonist M40 on Cardiac Function and Remodeling in Rats with Heart Failure.

BACKGROUND: Sympathetic activation and parasympathetic withdrawal are important characteristics of heart failure. Recent studies demonstrate that galanin reduces the discharge of acetylcholine and inhibits vagal bradycardia by acting on galanin receptor type 1 (GalR1). We speculated that blocking GalR1 is beneficial for heart failure. METHODS: Rats with heart failure were induced by myocardial infarction. The rats were injected intraperitoneally with galanin receptor antagonist M40 solution (30 nmol/kg) or saline for 4 weeks. Cardiac function was assessed by echocardiography and brain natriuretic peptide (BNP) in plasma. The ratio of heart weight to body weight (HW/BW), hematoxylin-eosin (HE), and Masson trichrome stain was used to evaluate cardiac remodeling. Tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6) in plasma, and sarco(endo)plasmic reticulum Ca(2+) -ATPase (SERCA2) in heart tissue were detected to confirm the mechanism of the cardioprotection effect. RESULTS: Compared with rats injected with saline, M40 effectively improved cardiac function of contraction; decreased BNP, IL-6, and HW/BW (all P < 0.05); attenuated cardiac fibrosis; and upregulated SERCA2 (P < 0.05). CONCLUSION: M40 improves cardiac function and attenuates remodeling, suggesting that galanin receptor antagonist may be a potential therapeutic agent for HF.

Feasibility and efficacy of a remote real-time wireless ECG monitoring and stimulation system for management of ventricular arrhythmia in rabbits with myocardial infarction.

The purpose of this study was to explore the feasibility of continuous remote monitoring, and the induction and termination of malignant ventricular arrhythmias (VAs) by a novel implantable electronic cardiovascular device (IECD) system in rabbits with myocardial infarction (MI). The IECD was implanted and MI was induced by ligation of the left anterior descending coronary artery in 20 adult rabbits. Internet-based remote electrocardiogram (ECG) monitoring and ventricular stimulation were conducted in remote locations with internet access. The voltage amplitudes of the stimulation signals were recorded synchronously by remote and surface ECG. Programmed stimulation with regular stimuli and regular stimuli with an added extra stimulus were performed prior to and following the MI surgery to induce and terminate VAs. IECD implantation and MI surgery, as well as qualified remote and bidirectional signal communications between the implanted IECD and extracorporeal system, were successfully achieved in 18 rabbits. The voltage of the stimulation signals recorded by the remote and surface ECGs showed a good correlation with the stimulation current (remote ECG, r=0.972 and surface ECG, r=0.988; P<0.001). Sustained ventricular tachycardia (VT) was induced in five rabbits (5/20, 25%) prior to MI induction and in 12 rabbits (12/16, 75%) following MI induction. Of the 17 induced VTs, 16 were successfully terminated by remote ventricular stimulation. The novel IECD system provides qualified remote wireless ECG monitoring and possesses the potential to induce and terminate VAs by remote ventricular pacing in this rabbit model of MI. Thus, this model of MI may be used to test the efficacy of novel drugs and devices for the management of VAs.

Experimental observation of vitro pigs' hearts with bipolar radiofrequency ablation.

Bipolar ablation is an innovative direction of catheter ablation technology. The aim of this study was to investigate the damaged area of bipolar radiofrequency ablation in vitro pigs' hearts under different conditions and to evaluate the effectiveness and safety. The bipolar radiofrequency ablation was performed in vitro pigs' hearts with a 4 mm bipolar electrode under different conditions at various combinations of the parameters (Distance: from 12 mm to 17 mm; Power: 30 w or 40 w; Time: from 20 s to 90 s; Temperature: 45°C or 60°C; Saline Perfusion: 0 ml/h, 1000 ml/h or 1500 ml/h). We measured the length, width, depth, connection rate and blasting rate of the connective ablation lesion and then evaluated the effectiveness and safety of connective ablation lesion. Numerical analysis showed that there was a positive correlation between the time, temperature and the length, depth, connection rate, blasting rate. There was a negative correlation between the power, perfusion and the depth, while other indexes were positively correlated with the power, perfusion. Distance and length were positively correlated, while other indexes were negatively correlated with the distance. Regression analysis showed that the infusion was not significantly correlated with the depth, connection rate, blasting rate. The temperature was not significantly correlated with the length, connection rate. Power and depth's correlation was not significant. When the parameter combination was 12 mm, 20 s, 30 w, 60°C, 1500 ml/h, the effectiveness and safety was optimum, with the mean lesion length being 19.89 ± 3.02 mm, the depth of an average being 3.50 ± 0.63 mm, the connection rate and the blasting rate being 100% and 13.9% respectively. The bipolar ablation in vitro pigs' hearts could form the most stable continuous damage.