A Green Protocol for the Electrochemical Synthesis of a Fluorescent Dye with Antibacterial Activity from Imipramine Oxidation

Electrochemical oxidation of imipramine (IMP) has been studied in aqueous solutions by cyclic voltammetry and controlled-potential coulometry techniques. Our voltammetric results show a complex behavior for oxidation of IMP at different pH values. In this study, we focused our attention on the electrochemical oxidation of IMP at a pH of about 5. Under these conditions, our results show that the oxidation of IMP leads to the formation of a unique dimer of IMP (DIMP). The structure of synthesized dimer is fully characterized by UV-visible, FTIR, 1H NMR, 13C NMR and mass spectrometry techniques. It seems that the first step in the oxidation of IMP is the cleavage of the alkyl group (formation of IMPH). After this, a domino oxidation-hydroxylation-dimerization-oxidation reaction, converts IMPH to (E)-10,10',11,11'-tetrahydro-[2,2'-bidibenzo[b,f]azepinylidene]-1,1'(5H,5'H)-dione (DIMP). The synthesis of DIMP is performed in an aqueous solution under mild conditions, without the need for any catalyst or oxidant. Based on our electrochemical findings as well as the identification of the final product, a possible reaction mechanism for IMP oxidation has been proposed. Conjugated double bonds in the DIMP structure cause the compound to become colored with sufficient fluorescence activity (excitation wave-length 535 nm and emission wave-length 625 nm). Moreover, DIMP has been evaluated for in vitro antibacterial. The antibacterial tests indicated that DIMP showed good antibacterial performance against all examined gram-positive and gram-negative bacteria (Staphylococcus aureus, Bacillus cereus, Escherichia coli and Shigella sonnei).

Unpredictable Oscillations for Hopfield-Type Neural Networks with Delayed and Advanced Arguments

This is the first time that the method for the investigation of unpredictable solutions of differential equations has been extended to unpredictable oscillations of neural networks with a generalized piecewise constant argument, which is delayed and advanced. The existence and exponential stability of the unique unpredictable oscillation are proven. According to the theory, the presence of unpredictable oscillations is strong evidence for Poincaré chaos. Consequently, the paper is a contribution to chaos applications in neuroscience. The model is inspired by chaotic time-varying stimuli, which allow studying the distribution of chaotic signals in neural networks. Unpredictable inputs create an excitation wave of neurons that transmit chaotic signals. The technique of analysis includes the ideas used for differential equations with a piecewise constant argument. The results are illustrated by examples and simulations. They are carried out in MATLAB Simulink to demonstrate the simplicity of the diagrammatic approaches.

Abstract 15430: Comparison of Ventricular Activation Time in Sinus and His Bundle Paced Beats

Introduction: The relationship between conduction time of a sinus impulse and a paced impulse from His bundle to peak of left ventricular activation (HVAT) has not been systematically studied. Hypothesis: To perform a comparative analysis of HVAT of sinus and paced impulse in non-selective (NS) His bundle pacing (HBP) and selective (S)-HBP. Furthermore, to determine if pacing voltage and presence of His Purkinje system (HPS) disease affects HVAT. Methods: In 102 consecutive patients a comparative analysis of native HVAT and paced HVAT at higher (5-volt) and lower voltage (1-volt) was done in all patients and in groups subdivided into NS-HBP, S-HBP, with and without HPS disease. Results: Compared to sinus HVAT (105.9 ± 24.0 ms), paced HVAT was shorter at 5-volt (97.2 ± 17.9 ms) ( p<0.01 ) and longer at 1-volt ( p<0.01 ). This voltage effect was significant only in NS-HBP (-15.8 ± 15.7 ms, p<0.01 ) but not in selective-HBP (-6.2± 13.6 ms p=0.16 ). In NS-HBP, decrease in HVAT caused by 5-volt was the same in normal vs diseased HPS (-14.5 ± 12.8 vs-13.2 ±16.3 ms). Conclusions: 1) Compared to sinus HVAT, NS-HBP HVAT is significantly shorter at 5-volt, however, tends to prolong at 1-volt.2) The 1-volt to 5-volt HVAT decrease appears to be similar both normal and diseased NS-HBP thus not related to correction of HPS delay. 3) The voltage related decrease in HVAT is significant in presence of pre-excitation wave seen in NS-HBP and is not significant in S-HBP.

Non-invasive detection of arrhythmogenic foci of atria by using the cardioelectric field on the surface of the body during experimental pulmonary hypertension

Aim. The potential distribution of the cardioelectric field on the body surface during the initial atrial activity and the sequence of depolarization of the atrial subepicardium in rats with experimentally induced pulmonary hypertension were compared. This work is devoted to non-invasive detection of arrhythmogenic foci of atria by using the cardioelectric field on the body surface during experimental pulmonary hypertension.Materials and methods. The method of cardioelectrochronotopography has been used to study the electric field of the heart on the body surface and the sequence of propagation of the excitation wave along the atrial epicardium in rats with experimentally induced pulmonary hypertension caused by a single injection of monocrotaline (60 mg / kg, four weeks after drug administration).Results. Pulmonary hypertension causes the appearance of an additional focus of initial excitation in the area of the pulmonary vein lacunae, which leads to an increase in the heterogeneity of the propagation of the excitation wave along the atrial epicardium. The appearance of the additional excitation focus in the mouths of the pulmonary veins in the left atrium changes the picture of the sequence of depolarization of the atrial epicardium. The heterogeneity of the propagation of the excitation wave along the atrial epicardium is reflected in a different arrangement of zones of positive and negative cardioelectric potentials on the body surface before and during the P-wave in comparison with the initial state.Conclusion. Induced pulmonary hypertension contributes to the appearance of an additional focus of initial excitation in the area of the sleeves of the pulmonary veins of the left atrium in rats. This leads to an increase in the heterogeneity of the propagation of the excitation wave along the atrial epicardium. This is also reflected in the change in the arrangement of the zones of positive and negative cardioelectric potentials on the body surface before and during the P-wave in comparison with the initial state.

Spiral wave initiation in excitable media

Spiral waves represent an important example of dissipative structures observed in many distributed systems in chemistry, biology and physics. By definition, excitable media occupy a stationary resting state in the absence of external perturbations. However, a perturbation exceeding a threshold results in the initiation of an excitation wave propagating through the medium. These waves, in contrast to acoustic and optical ones, disappear at the medium's boundary or after a mutual collision, and the medium returns to the resting state. Nevertheless, an initiation of a rotating spiral wave results in a self-sustained activity. Such activity unexpectedly appearing in cardiac or neuronal tissues usually destroys their dynamics which results in life-threatening diseases. In this context, an understanding of possible scenarios of spiral wave initiation is of great theoretical importance with many practical applications. This article is part of the theme issue ‘Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)’.