Electrostimulus

Abstract: Special electrosensory cells are sensitive to electric fields and give responses upon stimulation, but little is known about normal regular cells and cancerous cells. Herein, by designing nucleus- and mitochondria-targeting SERS nanoprobes combined with fluorescent monitoring of the mitochondrial membrane potential (MMP) variations, we found an interesting electrosensory and self-healing response in MMP within cancerous and normal cells during periodic impulse electrostimulation (IES). More importantly, the key regulator role of phenylalanine (phe) was revealed by cell fluorescent imaging and SERS detection, whose expression level was increased in response to IES to induce cell apoptosis. During IES off-state, the self-repair function of cells was activated to reduce phe release. We also found that cancerous cells (MCF-7 and HeLa cells) demonstrated a response more remarkable than that of normal cells (L929 and H8 cells) to periodic IES. Our finding revealed a common electrosensory and self-repair biofunction of cells and its related phe metabolism response. Understanding the difference of biophysical/electrophysiological responses between cancerous and normal cells may broaden the view for cancer therapy in the future.

Abstract: Objective To explore the correlation of tip perfusion index (TPI) with the hemodynamics and catechalomines and to assess the value and meaning of TPI for monitoring stress responses in general anesthesia. Methods Twenty patients who were to receive selective neurosurgery underwent induction and maintenance of propofol and remifentanil by target controlled infusion (TCI). A 60mA-5OHz5s electrostimulus was applied before tracheal intubation and head holder setting respectively. TPI, SBP,diastolic blood pressure (DBP), heart rate (HR), and bispectral index (BIS) were recorded at nine time points: before induction (baseline), before and after electrostimulation, before and after tracheal intubation, before and after electrostimulation, and before and after head holder setting. The changes of parameters (△TPI,△SBP,△DBP,△HR, and △BIS) were calculated after each stimulation. Five out of 20 patients were selected randomly to monitor the plasma concentration of catecholamine at the above time points. The responses to tracheal intubation and head holder setting were defined as the SBP increasing >15mm Hg over the baseline value. Results △TPI was significantly correlated with △SBP and △DBP (r=0.623 and 0.317, P<0.01 and 0.05). The responses to tracheal intubation and head holder setting were inhibited effectively when the △TPI caused by electrostimulus was less than 10% of the pre-electrostimulus TPI. TPI was significantly negatively correlated with the plasma Concentrations of norepinephrine and epinephrine (r=-0.679, and r=-0.364, P<0.05 and 0.O1). Conclusion (1)The TPI change is correlated well with the blood pressure change during stresses, and the TPI change caused by electrostimulus can predict the blood pressure change caused by tracheal intubation and head holder setting. (2) The TPI change reflects the norepinephrine plasma level indirectly. Key words: Photoplethysmography; Hemodynamics ; Catechalomines ; Stress ; General anesthesia

Abstract: Through intracellular observations of the cat spinal motoneuron both mono-and polysynaptic reflex arcs were shown to participate in repetitive activation of stretch reflex. Experiments were performed on 25 cats anesthetized by intraperitoneal (i.p.) injection of 3cc/kg of a mixture of 1% chloralose and 10% urethane. Driving of the motoneuronal discharges accomplished by electric stimulation (16-100Hz) of the gastrocnemius lateralis and medialis nerves.Repeated electric stimulation of muscle nerves elicited monosynaptic ‘vibratory’ EPSPs and a polysynaptic ‘augmenting’ EPSP in the moto-neuron.The firing of the motoneuron occurred when a temporal summation of the ‘vibratory’ EPSPs was sufficiently obtained. The discharge frequency of motoneuron, MNf, was expressed as a product of electrostimulus frequency, Sf, and reciprocal of an integer, n, i. e. MNMf=(1/n)Sf. An increase in the stimulus intensity resulted in a diminution of the vibratory EPSP and a remarkable increase of n. This was assumed to be due to an inhibitory process produced by the Group II fibers.The minimum value of integer n was always a determinant factor for the maximum value of MNf which was referred to as the ‘preferred’ frequency of the motoneuron.Long-lasting electric stimulation of muscle nerves was followed by a more remarkable recruitment of the augmenting EPSP which made the motoneuron attain its critical threshold of firing. Motoneuronal spikes elicited by such a large augmenting EPSP were not locked to the Ia impulses. Unlocked spikes were observed only in a later stage of electric stimulation of Ia fibers.