Reduction In Electrical Activity Research Articles

Full-field stimulus threshold testing for evaluation of the retinal function in patients with inherited retinal dystrophy

Objective: To analyze the characteristics of full-field stimulus thresholds (FST) in patients with middle-and late-stage inherited retinal dystrophy (IRD), and to explore the feasibility of the FST test in evaluating the retinal function for IRD patients. Methods: It was a retrospective case series study. Twenty-eight patients with IRD whose full-field electroretinogram (ERG) results showed no electrical activity (20 patients) or a serious decrease in electrical activity (8 patients) were enrolled, including 17 males and 11 females, with a median age of 32 years. Ten normal controls were also enrolled. All eyes had a measurement of best corrected visual acuity (BCVA) and an ERG test. FST stimulated by red, blue and white lights were examined with an electrophysiological instrument. The decimal value of BCVA was converted to logarithm of the minimum angle of resolution. Data of the better eye of each participant were used for statistical analysis. Independent sample t-test was used to analyze the difference in FST among patients. Linear regression was used to analyze the correlation between FST, visual acuity and ERG amplitudes. Results: The BCVA of all eyes was 0.7±0.6. Under the stimulation of red, blue and white lights, the FST were(-27.0±7.1), (-47.4±12.2) and(-41.7±11.5) dB in the 8 eyes with decreased electrical activity, (-16.3±7.0), (-27.2±13.7) and(-23.5±12.5) dB in the 20 eyes with no electrical activity, and(-39.9±4.0), (-65.8±4.0) and(-58.5±3.4) dB in the 10 control eyes, respectively. The FST of IRD patients were higher than the normal controls. The FST with red, blue and white lasers in eyes with no electrical activity were higher than those with severely reduced electrical activity (t=-3.472, -3.506, -3.433; all P=0.002). The BCVA was not correlated with the FST under the red, blue and white light stimulation in eyes with a serious reduction in electrical activity (r=0.134, 0.011, 0.010; P=0.055, 0.601, 0.611). There was a linear correlation between the red light stimulus FST and the b-wave amplitude of flicker ERG response (r=-0.591, P=0.026), but there was no significant correlation between other amplitudes and FST. Conclusions: The FST test is a supplementary method to evaluate the retinal function of patients with middle-and late-stage IRD. It can quantitatively reflect the function of rod and cone cell system. As the retinal function of IRD patients decreases, the FST gradually increase.

The effect of proportional assist ventilation on the electrical activity of the human diaphragm during exercise.

What is the central question of this study? What is the effect of lowering the normally occurring work of breathing on the electrical activity and pressure generated by the diaphragm during submaximal exercise in healthy humans? What is the main finding and its importance? Ventilatory assist during exercise elicits a proportional lowering of both the work performed by the diaphragm and diaphragm electrical activity. These findings have implications for exercise training studies using proportional assist ventilation to reduce diaphragm work in patients with cardiopulmonary disease. We hypothesized that when a proportional assist ventilator (PAV) is applied in order to reduce the pressure generated by the diaphragm, there would be a corresponding reduction in electrical activity of the diaphragm. Healthy participants (five male and four female) completed an incremental cycle exercise test to exhaustion in order to calculate workloads for subsequent trials. On the experimental day, participants performed submaximal cycling, and three levels of assisted ventilation were applied (low, medium and high). Ventilatory parameters, pulmonary pressures and EMG of the diaphragm (EMGdi ) were obtained. To compare the PAV conditions with spontaneous breathing intervals, ANOVA procedures were used, and significant effects were evaluated with a Tukey-Kramer test. Significance was set at P<0.05. The work of breathing was not different between the lowest level of unloading and spontaneous breathing (P=0.151) but was significantly lower during medium (25%, P=0.02) and high (36%, P<0.001) levels of PAV. The pressure-time product of the diaphragm (PTPdi ) was lower across PAV unloading conditions (P<0.05). The EMGdi was significantly lower in medium and high PAV conditions (P=0.035 and P<0.001, respectively). The mean reductions of EMGdi with PAV unloading were 14, 22 and 39%, respectively. The change in EMGdi for a given lowering of PTPdi with the PAV was significantly correlated (r=0.61, P=0.01). Ventilatory assist during exercise elicits a reduction in the electrical activity of the diaphragm, and there is a proportional lowering of the work of breathing. Our findings have implications for exercise training studies using assisted ventilation to reduce diaphragm work in patients with cardiopulmonary disease.

Inhibitory role of taurine in the caudal neurosecretory Dahlgren cells of the olive flounder, Paralichthys olivaceus

Taurine plays role in neural development and physiological functions such as endocrine regulation in the central nervous system (CNS), and it is one of the most abundant free amino acid there. We investigated its potential effect as a neurotransmitter in the group of neuroendocrine Dahlgren cells at flounder Paralichthys olivaceus caudal neurosecretory system (CNSS). The application of taurine in vitro led to a reduction in electrical activity of Dahlgren cells, followed by a rise in the number of silent cells, at the same time the frequency of all three activity patterns (tonic, phasic, bursting) in Dahlgren cells was reduced. Both strychnine (a glycine receptor antagonist) and bicuculline (a GABAA receptor antagonist) can block the response to taurine separately. Transcriptome sequencing analysis showed the existence of glycine receptor (GlyR) and GABAA receptor (GABAAR) in the flounder CNSS, and the GlyR, GABAAR, and Cl- channel mRNA expression were significantly raised after taurine superfusion according to quantitative RT-PCR results. These data indicate that taurine may mediate Dahlgren cell population of CNSS activity in vivo through GlyR and GABAAR, thereby, regulating stress-response.

Evaluation of the impact of preoperative use of dexamethasone and cyclobenzaprine in surgical extraction of lower third molars on trismus by electromyographic analysis.

The aim of this study was to evaluate the influence of cyclobenzaprine and dexamethasone on ​the electrical activity of the masticatory muscles in patients who had undergone lower third molar surgery. Thirty bilateral impacted lower third molars with indication of extraction were randomised into three groups: the control group, the dexamethasone, and the cyclobenzaprine group. To obtain muscular electrical activity and mouth opening, an electromyographic device was used at mandibular rest and maximum voluntary contraction and compared pre- and post-operatively. During muscle contraction, no significant difference was observed in the electromyographic records on the non-operated side. On the operated side, there was a reduction in electrical activity for both drugs pre-operatively and immediately post-operatively compared to the control group. All pharmacological agents promoted a higher mouth opening compared to control group. The results suggest that dexamethasone and cyclobenzaprine may be useful as an adjuvant in the prevention of motor dysfunctions in third molar surgery.

Peptide-siRNA Supramolecular Particles for Neural Cell Transfection.

Small interfering ribonucleic acid (siRNA)‐based gene knockdown is an effective tool for gene screening and therapeutics. However, the use of nonviral methods has remained an enormous challenge in neural cells. A strategy is reported to design artificial noncationic modular peptides with amplified affinity for siRNA via supramolecular assembly that shows efficient protein knockdown in neural cells. By solid phase synthesis, a sequence that binds specifically double‐stranded ribonucleic acid (dsRNA) with a self‐assembling peptide for particle formation is integrated. These supramolecular particles can be further functionalized with bioactive sequences without affecting their biophysical properties. The peptide carrier is found to silence efficiently up to 83% of protein expression in primary astroglial and neuronal cell cultures without cytotoxicity. In the case of neurons, a reduction in electrical activity is observed once the presynaptic protein synaptophysin is downregulated by the siRNA–peptide particles. The results demonstrate that the supramolecular particles offer an siRNA delivery platform for efficient nonviral gene screening and discovery of novel therapies for neural cells.

Shield effect of resistance jumping training on biomechanical parameters in gastrocnemius muscles of diabetic animals

Background Chronic hyperglycemia resulting from diabetes mellitus undertakes several body cells through the formation of advanced glycation end products and activation of the polyol pathway (Brownlle, 2005), promoting reduction of electrical activity in skeletal muscle and the regenerative capacity of its cells, as well as impaired contractility and increased tissue stiffness. In turn, the amplify muscle work during exercise is able to elicit several essential biochemical reactions for hypertrophy, power gain and enhance muscle function (Andersen et al., 1996, 1997, 2004, 2005).

Silencing of PNPLA6, the neuropathy target esterase (NTE) codifying gene, alters neurodifferentiation of human embryonal carcinoma stem cells (NT2)

Neuropathy target esterase (NTE) is a protein involved in the development of a polyneuropathy caused by exposure to certain organophosphorus compounds. In vivo and in vitro studies have also associated NTE with embryonic development since NTE null mice embryos are non-viable, and silencing the NTE-codifying gene (Pnpla6) in mouse embryonic stem cells strongly alters the differentiation of vascular and nervous systems. In this paper, human embryonal carcinoma stem cells human-derived NTera2/D1 (hNT2) are used as an in vitro neurodifferentiation model to determine whether PNPLA6 silencing is able to alter the differentiation process. In control cultures, PNPLA6 mRNA levels increased in parallel with other neuroectodermal markers during neurodifferentiation. PNPLA6 silencing with specific interference RNA reached a 97% decrease in gene expression 3days after transfection and with a maximum reduction in NTE enzymatic activity (50%), observed on day 4. Silencing PNPLA6 showed an 80% decrease in quantifiable neuronal cells after 13days in vitro (DIV) compared to controls and absence of different neuronal markers after 66DIV. Microarray data analysis of the PNPLA6-silenced cells showed alterations in several developmental processes, mainly neurogenesis and epithelium tube morphogenesis. PNPLA6 silencing also led to a reduction in electrical activity and an altered neuronal phenotype. This work is the first proof supporting the hypothesis that NTE plays a role in human early neurodevelopment using a human cell differentiation model.

Examination of muscle activity with an elastic hamstring assistance device

Background: Hamstring injuries are common among athletes and recreationally active people. The goal of the study was to determine if the Hamstrong device was effective in reducing the activity of the hamstring muscles during isometric knee exercise. Materials and Methods: Electrodes were placed on the biceps femoris and semitendinosus in a bipolar configuration on the left leg of all the subjects (N = 12) in order to monitor muscle activity during the experimental procedure. The test involved isometrically holding 15%, 30%, 45%, and 60% of the participant's pre-determined maximum isometric force at 90° and 135° knee extension with and without the Hamstring apparatus. The raw electromyography (EMG) signal was low-pass filtered and amplified prior to being interpreted. Results: There was a significant difference in the signal from the biceps femoris determined via surface electromyography (sEMG) at 90 degrees of knee extension using 30% of peak isometric force as the load (P = 0.043). Additionally in the biceps femoris there were differences in the sEMG signal at 135 degrees of knee extension using 15% (P = 0.0492) and 30% (P = 0.0358) of peak isometric force. In the semitendinosus muscle, there was a significant difference in sEMG signal at 15° of knee extension with 60% of peak isometric force (P = 0.0025). Overall, clinical inferences revealed that the device could be considered 71.4% beneficial or substantially positive to 10.9% for reducing the EMG signal associated with isometric exercise in the biceps femoris (biceps femoris mean: With device 0.319 mV ± 0.13 and without device 0.361 mV ± 0.14). Similarly, six out of eight conditions resulted in lower muscle activation from the semitendinosus with the apparatus. For the semitendinosus muscle, the range was from 43.9% beneficial to 0.1% beneficial (semitendinosus mean: With device 0.327 mV ± 0.09 and without device 0.339 mV ± 0.09). Conclusion: The reduction in electrical activity of the biceps femoris and the semitendinosus during the isometric hold with the Hamstring apparatus suggests that the elastic hamstring assistance device effectively assists in knee flexion and could potentially be used for rehabilitation purposes.

A fast and robust algorithm for Bader decomposition of charge density

An algorithm is presented for carrying out decomposition of electronic charge density into atomic contributions. As suggested by Bader [R. Bader, Atoms in Molecules: A Quantum Theory, Oxford University Press, New York, 1990], space is divided up into atomic regions where the dividing surfaces are at a minimum in the charge density, i.e. the gradient of the charge density is zero along the surface normal. Instead of explicitly finding and representing the dividing surfaces, which is a challenging task, our algorithm assigns each point on a regular ( x, y, z) grid to one of the regions by following a steepest ascent path on the grid. The computational work required to analyze a given charge density grid is approximately 50 arithmetic operations per grid point. The work scales linearly with the number of grid points and is essentially independent of the number of atoms in the system. The algorithm is robust and insensitive to the topology of molecular bonding. In addition to two test problems involving a water molecule and NaCl crystal, the algorithm has been used to estimate the electrical activity of a cluster of boron atoms in a silicon crystal. The highly stable three-atom boron cluster, B 3I is found to have a charge of −1.5 e, which suggests approximately 50% reduction in electrical activity as compared with three substitutional boron atoms.

Dopant electrical activity and majority-carrier mobility in B- and Sb- delta -doped Si thin films.

The electrical characteristics of Si films grown by low-temperature molecular-beam epitaxy and doped with Sb or B in single or multiple \ensuremath{\delta}-like doping profiles have been investigated. Two-dimensional concentrations ranging from \ensuremath{\approxeq}${10}^{13}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ to 5\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ have been realized. For single doping spikes Hall measurements indicate an apparent reduction in electrical activity to about 50%. This is linked to the confinement of the carriers in the potential well of the doping spike. The reduced electrical activity is not due to growth imperfections. The effect of the confinement on the Hall measurements can be reduced in \ensuremath{\delta}-doping superlattices, provided the distance between doping spikes is sufficiently small. For ${\mathit{N}}_{\mathrm{Sb}}^{2\mathrm{D}}$=${10}^{13}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ the mobility in a \ensuremath{\delta}-doping superlattice drops exponentially as a function of inverse spike spacing until, at about 5 nm, a value close to the mobility in an equivalent, uniformly doped film (${\mathit{N}}_{\mathrm{Sb}}$\ensuremath{\approxeq}3\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$) is reached. Carrier mobilities in \ensuremath{\delta}-doped layers far exceed those of uniformly doped layers of equivalent concentration. Electron mobilities reach 400 ${\mathrm{cm}}^{2}$/V s for a sheet concentration of 1\ifmmode\times\else\texttimes\fi{}${10}^{13}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ and are still at \ensuremath{\approxeq}40 ${\mathrm{cm}}^{2}$/V s at ${\mathit{N}}_{\mathrm{Sb}}^{2\mathrm{D}}$=5\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. For p-type doping these numbers are 180 and 20 ${\mathrm{cm}}^{2}$/V s, respectively.

Inhibition of sympathetic nerve activity by acute administration of the tricyclic antidepressant desipramine

In rats anesthetized with pentobarbital/chloral hydrate, the i.v. injection of desipramine (0.3 mg/kg) caused a rapid fall in mean arterial blood pressure accompanied by a reduction in efferent renal nerve integrated activity. A similar reduction in electrical activity was seen in the preganglionic splanchnic nerve. Pretreatment of the rats with yohimbine (0.3 mg/kg) increased renal nerve activity by 20%, and the decrease in blood pressure and renal nerve activity elicited by a subsequent dose of desipramine was blocked. I.v. injection of prazosin (0.05 mg/kg) caused a reduction in systemic blood pressure. The hypotensive effect of a subsequent dose of desipramine was largely blocked, whereas the fall in renal nerve activity was attenuated, but still present. The data are consistent with an action of desipramine to reduce central sympathetic tone by increasing the release of endogenous noradrenaline which acts on α 2-adrenoceptors at CNS sites controlling sympathetic activity. An additional involvement of central α 1-adrenoceptors cannot be ruled out.

Some effects of sodium nitroprusside, methoxyverapamil (D600) and nifedipine on rat portal vein.

1 The effects of methoxyverapamil (D600), nifedipine and sodium nitroprusside on noradrenaline-induced electrical and mechanical activity in rat portal vein have been examined. 2 D600 and nifedipine produced a concentration-dependent reduction in mechanical responses to noradrenaline whilst sodium nitroprusside had no effect. The effects of D600 and nifedipine were reversed by increasing the extracellular calcium concentration. 3 The mechano-inhibitory effects of D600 were accompanied by a marked reduction in electrical activity with some evidence of electromechanical uncoupling. 4 The mechano-inhibitory effects of nifedipine were associated with considerable electromechanical uncoupling. 5 It is concluded that in the concentrations used, D600 acts primarily by inhibiting calcium influx with some effect on electromechanical coupling whilst nifedipine interferes mainly with the coupling process. The inactivity of sodium nitroprusside suggests that the excitation-contraction coupling process in rat portal vein is relatively simple and further studies with this tissue seem indicated.

Reduction of stuttering frequency using analog electromyographic feedback.

Three stutterers were taught to reduce resting muscle activity by using analog electromyographic feedback from four sites over different muscle groups. They were then trained to reduce muscle activity prior to uttering selected sentences. A functional analysis was performed to determine the relationship between the decrease in stuttering frequency on initial phonemes and the reduction of electrical activity at each muscle site. Subjects demonstrated different responses to training. One subject's greatest decrease in stuttering frequency was associated with muscle activity training at a lip site. A second subject's greatest decrease in stuttering was associated with training at a laryngeal site. A third subject's greatest decreases in stuttering were with both lip and laryngeal site training. Following these demonstrations that stuttering could be controlled with electromyographic feedback, a practical management program was designed for a fourth stutterer. Feedback training to reduce electromyographic activity when paired with speech resulted in elimination of stuttering in two monitored situations, conversations and telephone calls. Probes indicated the stuttering continued to be markedly reduced in all situations nine months after treatment.

A mechanism for the electrocardiogram response to left ventricular hypertrophy and acute ischemia.

A proposed mechanism for explaining the electrocardiographic response in left ventricular hypertrophy and in subendocardial and epicardial acute ischemia was incorporated in a mathematical model of electrical heart activity. The model of hypertrophy was simply an increase in cell size, and the principal effect on the computer-generated 12-lead electrocardiograms (ECGs) was an increase in R-wave amplitude and ventricular activation time and a flattening or polarity reversal of the T wave. The model of acute ischemia was a reduction between plateau and resting potential of the transmembrane action potential. The principal effect on the computer-generated 12-lead ECGs was an S-T segment displacement up or down depending on the location of the lesion. This shift was linearly proportional to the severity of the ischemia, i.e., the reduction in electrical activity of the ischemic cell, and for a lesion of given severity the S-T segment shift was a measure of the area, not the volume, of ischemic tissue. Therefore, this model suggests that a direct correlation does not necessarily exist between volume-measuring tests such as serum enzyme values in the case of necrosis and S-T segment shifts.

Changes in the EEG during and after a course of carbon dioxide and hydrogen sulfide baths

Long-term experiments were carried out on dogs. The action of a single carbon dioxide or hydrogen sulfide bath produced a reduction in electrical activity of the cortical area representing the skin analyzer.

Spinal currents in regulation of respiratory movements (Electromyographic study)

Division of the dorsal roots at the level C5−C7 caused a transitory reduction of electrical activity of the diaphragm on the same side. Division of the posterior roots of the level T2−T8 caused a disappearance or a marked reduction of the activity of the intercostal muscles on that side which was maintained the whole observation period (up to 24 h).

PROGNOSTIC SIGNIFICANCE OF ELECTROMYOGRAPHY IN CONGENITAL TORTICOLLIS

The selection of the patients with congenital muscular torticolis for early surgical treatment is of paramount importance because in severe cases the deformity is progressive, and surgical treatment produces the best results when the diseased and restraining muscle is removed in early infancy. Electromyography appears to be of some value as an adjunct to clinical evaluation in determining which patient should have such early surgical treatment. The electromyogram permits the physician to obtain an objective estimate of the amount of destruction present in any given muscle. If few muscle fibers are working, he may conclude that the muscle has been replaced by fibrous tissue and that structural deformities are likely to progress due to the disproportionate growth of the diseased area in comparison to the surrounding normal boney and soft tissues. Conversely, if there are many normal muscles fibers functioning within the mass he may predict a more favorable outcome in terms of muscle length and function and consequently less deformity in the future. Our observations to date indicate that if there is a severe reduction in electrical activity of the involved sternoleidomastoid muscle, as indicated by the electromyogram, the histologic studies will show evidence of extensive destruction of normal muscle and replacement with scan tissue. In such a patient early surgical excision is probably justified. Conversely, if there is minimal or moderate reduction in electrical activity, conservative management with physical therapy and repeated observations is the treatment of choice.

Electromyography of intrinsic and extrinsic laryngeal muscles during silent speech: correlation with reading activity.

During “silent speech” an increase in electrical activity was found in the vocal and the mylohyoid muscle. In the posterior crico-arytenoid muscle there was a reduction in electrical activity. The change in electrical activity was considerable in subjects with low reading ability.