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PubMed1983

Tracing the use of torture: electrically induced calcification of collagen in pig skin.

Reports of the use of electrical torture are usually denied, so that there is an urgent need of diagnostic methods to distinguish the consequences of electrical torture from other superficial injuries. The 'electrical group' of Anti-Torture Research (ATR) has accordingly studied the possibility of distinguishing between the sequelae of electrical and heat injury. Among the reported differences of the two types of injuries is the occurrence in epidermis, vessel walls and sweat glands of vesicular nuclei exclusively in electrically injured skin. On the basis of experiments with anaesthetized pigs, we now report that the late sequelae of electrical injury appear to include the deposition of calcium salts beneath the area of an electrical cathode.

Aggression↗

PubMed1999

Increased doxorubicin uptake and toxicity in multicellular tumour spheroids treated with DC electrical fields.

Electrochemotherapy (ECT) is a new approach to the treatment of tumours. In the present study, multicellular prostate tumour spheroids were treated with non-lethal direct current (DC) electrical fields, and uptake and toxicity of doxorubicin were investigated. An electrical field with a field strength of 500 Vm(-1) applied for a duration of 90 s resulted in neither reversible nor irreversible membrane breakdown as revealed by fluid phase uptake studies of the membrane impermeant tracer Lucifer yellow. However, treated spheroids showed an increased uptake of doxorubicin and, consequently, an increased toxicity following electrical field exposure. The electrical field raised intracellular reactive oxygen species (ROS) as revealed using 2',7'-dichlorofluorescein diacetate (H2DCFDA) as an indicator. ROS induced membrane lipid peroxidation since the lipid peroxidation end products malondialdehyde (MDA) and 4-hydroxy-2-(E)-nonenal (4-HNE) were detected after electrical field treatment. Moreover, lipid peroxidation decreased the lipid diffusion coefficient D from 4.2 x 10(-10) cm2 s(-1) to 2.7 x 10(-10) cm2 s(-1) in the control and treated sample, respectively, as revealed by fluorescence recovery after photobleaching (FRAP) experiments. The field effects could be mimicked by incubating spheroids with 100 nM hydrogen peroxide and were inhibited by the radical scavengers dehydroascorbate (DHA) and alpha-tocopherol (vitamin E), indicating that the increased uptake of doxorubicin after electrical field treatment is owing to lipid peroxidation and decreased membrane lipid mobility. Treatment of tumours with low intensity electrical fields may be useful to improve the cytotoxic capacity of anthracyclines.

Antineoplastic Agents↗

PubMed1997

Electrogastrography can recognize gastric electrical uncoupling in dogs.

BACKGROUND & AIMS: Electrical uncoupling is the lack of electrical synchronization in different parts of the stomach. The ability of electrogastrography (EGG) to recognize gastric electrical uncoupling has not been adequately studied. The aim of this study was to determine the impact on EGG of surgically introduced gastric uncoupling in anesthesized dogs. METHODS: Six pairs of bipolar electrodes were inserted into the antral gastric wall of 16 anesthetized dogs at laparotomy. Eight-channel bipolar cutaneous EGGs were simultaneously recorded. Three separate half-hour recordings were made from each dog in the basal state and after each of two circumferential cuts of all gastric muscle. The stomach was divided into three equally sized areas, each with an electrode pair in its anterior and posterior walls. Gastric electrical activity was assessed visually. EGG was digitized and processed by computer. RESULTS: Criteria for EGG normality were defined from 9 dogs with normal gastric electrical activity. After the first antral cut, internal recordings from the area below the division were at a lower frequency and often irregular. The second cut produced three different frequencies. Suggested criteria for normality allowed correct recognition of 93% of all severely abnormal records. Records with mild gastric electrical abnormalities were recognized with a sensitivity of 74%. CONCLUSIONS: EGG can recognize severe electrical uncoupling.

Animals↗

PubMed2002

A pulsed DC electric field affects P2-purinergic receptor functions by altering the ATP levels in in vitro and in vivo systems.

Recently it was shown that extracellular ATP, acting through purinergic receptors, has many physiological functions, including opening of Ca(2+)-ion channels, activation and mediation of signal transduction mechanisms as well as activation of the pain sensation. Since electrical stimulation is also known to affect many signal transduction processes as well as the alleviation of pain, we hypothesized that electric stimulation may affect the extracellular release of ATP. We investigated the effects of a small DC electric field (10(1)--10(2) V m(-1) range and with frequencies below 150 Hz) on the release of ATP in vitro (HeLa cells), and on the levels of ATP in vivo (the plasma of healthy volunteers). In HeLa cells ATP release was increased 50 fold, while the total amount of ATP in the cells was increased by 163%. In the plasma a significant decrease (P<0.05) in ATP concentration was seen after electrical stimulation, in all the volunteers. The small DC electric field also affected the cAMP signal transduction system in vitro (HeLa cells and human lymphocytes) and in vivo (human plasma). Decreased levels of cAMP (P<0.05) were seen in HeLa cells and increased levels of cAMP (P<0.05) in isolated human lymphocytes. The cAMP levels in the plasma of the electrically treated volunteers were lower than control values. These results show that the frequency, waveform and signal strength of the applied electric field are suitable for effecting measurable changes on signal transduction in vitro and in vivo.

Adenosine Triphosphate↗

PubMed1995

Autonomic nervous system disorders and reflex sympathetic dystrophy in lightning and electrical injuries.

Both lightning and electrical injuries can cause autonomic nervous system (ANS) symptoms and signs (Table 1). Published descriptions of ANS involvement occurring with lightning and electrical injuries are rare. The most often reported neurologic complications of lightning injuries involve the central nervous system. ANS abnormalities have been documented with lightning, although the descriptions are scant. There is a lack of complete clinical information or ANS testing data in these cases. This is usually a result of the transient nature of ANS complications. In electrical injuries, ANS involvement is less well described than for lightning. Electrical injuries can be associated with peripheral nerve damage. As a result of peripheral nerve damage, reflex sympathetic dystrophy (RSD) may occur in patients with electrical injuries. Various treatment strategies for RSD associated with electrical injuries are found in single case reports. This article summarizes ANS involvement, predominantly in lightning injuries, and describes RSD and its treatment, predominantly in electrical injuries.

Autonomic Nervous System Diseases↗

PubMed2003

Chemical synaptic activity modulates nearby electrical synapses.

Most electrically coupled neurons also receive numerous chemical synaptic inputs. Whereas chemical synapses are known to be highly dynamic, gap junction-mediated electrical transmission often is considered to be less modifiable and variable. By using simultaneous pre- and postsynaptic recordings, we demonstrate at single mixed electrical and chemical synapses that fast chemical transmission interacts with gap junctions within the same ending to regulate their conductance. Such localized interaction is activity-dependent and could account for the large variation in strength of electrical coupling at auditory afferent synapses terminating on the Mauthner cell lateral dendrite. Thus, interactions between chemical and electrical synapses can regulate the degree of electrical coupling, making it possible for a given neuron to independently modify coupling at different electrical synapses with its neighbors.

Afferent Pathways↗

PubMed1999

Nuclear hourglass technique: an approach that detects electrically open nuclear pores in Xenopus laevis oocyte.

Nuclear pore complexes (NPCs) mediate both active transport and passive diffusion across the nuclear envelope (NE). Determination of NE electrical conductance, however, has been confounded by the lack of an appropriate technical approach. The nuclear patch clamp technique is restricted to preparations with electrically closed NPCs, and microelectrode techniques fail to resolve the extremely low input resistance of large oocyte nuclei. To address the problem, we have developed an approach for measuring the NE electrical conductance of Xenopus laevis oocyte nuclei. The method uses a tapered glass tube, which narrows in its middle part to 2/3 of the diameter of the nucleus. The isolated nucleus is sucked into the narrow part of the capillary by gentle fluid movement, while the resulting change in electrical resistance is monitored. NE electrical conductance was unexpectedly large (7.9 +/- 0.34 S/cm(2)). Evaluation of NPC density by atomic force microscopy showed that this conductance corresponded to 3.7 x 10(6) NPCs. In contrast to earlier conclusions drawn from nuclear patch clamp experiments, NPCs were in an electrically "open" state with a mean single NPC electrical conductance of 1.7 +/- 0.07 nS. Enabling or blocking of active NPC transport (accomplished by the addition of cytosolic extracts or gp62-directed antibodies) revealed this large NPC conductance to be independent of the activation state of the transport machinery located in the center of NPCs. We conclude that peripheral channels, which are presumed to reside in the NPC subunits, establish a high ionic permeability that is virtually independent of the active protein transport mechanism.

Animals↗

PubMed2004

Effects of vitamin E and electrical stimulation on the denervated rat gastrocnemius muscle malondialdehyde and glutathione levels.

Effects of vitamin E treatment and local electrical stimulation on progression of atrophy in the denervated rat gastrocnemius muscle were studied. Denervation was performed by right leg sciatic nerve axotomy. Electrical stimulation (3-10 mA ms(-1), 10 min per day for 7 days) was applied to the right gastrocnemius muscle starting from day 1 of denervation. The muscle samples were assayed for malondialdehyde (MDA) and glutathione levels, as well as the histological appearance after 8 days of denervation. MDA levels were markedly increased following denervation. However, electrical stimulation, vitamin E treatment (30 mg kg(-1), i.m., everyday for 7 days), and combination of electrical stimulation and vitamin E treatment markedly reduced MDA levels. Glutathione levels were significantly decreased in the denervation group. Electrical stimulation, vitamin E treatment, and electrical stimulation plus vitamin E treatment prevented these reductions in glutathione levels. In the vitamin E treatment group, glutathione levels were markedly higher than in the control group. These results indicate that electrical stimulation and vitamin E treatment alone, or in combination, were able to prevent the effects of denervation on muscle atrophy.

Analysis of Variance↗

PubMed2004

Evaluating occupational 60-hertz electric-field exposures for guideline compliance.

This article examines determination of compliance of 60-Hz electric-field exposures with occupational guideline limits. The guidelines are expressed as a limit on the unperturbed electric field without allowance for the severity of potential spark discharges. A line worker on a 500-kV transmission-line tower provided a practical example of an occupational exposure. In this realistic case, the worker's posture, the uniformity of the field, and the field orientation differed from the guideline exposure scenario of standing erect in a vertical uniform field. An accurate estimate of the unperturbed nonuniform fields in the climbing space of a lattice steel structure was computed using Monte Carlo methods that modeled surface and spatial electric fields on and near standard geometrical elements. Fields were computed at 20 points in a three-dimensional array, simulating the location of the human body on the tower. We estimated the average unperturbed electric field, space potential, induced short-circuit current, induced open-circuit voltage, and the stored charge and energy available for a discharge over a range of capacitances to ground. The on-tower exposure parameters were compared with those from the idealistic guideline exposure scenario. The average electric field of 24.4 kV/m for the on-tower exposure exceeded the limit of 20 kV/m stated in the recently adopted IEEE Standard C95.6 2002. However, the charge available for a spark discharge during the on-tower exposure was less than that for the guideline exposure scenario. Thus, for an exposure limit based on a constant-charge criterion for adverse reaction to spark discharges, guideline on-tower exposure would be below the limit established for the guideline exposure scenario. Evaluation of electric-field exposures in terms of the charge associated with spark discharges provides a means of comparing any electric-field exposure scenario with the ideal guideline scenario in terms of an effects-related physical quantity. This approach is consistent with the exposure limit/basic restriction methodology that employs a basic restriction on a physical quantity as the ultimate determinant of compliance.

Electric Power Supplies↗

PubMed2005

Prediction of mechanical properties of human trabecular bone by electrical measurements.

In trabecular bone, the interrelationships of electrical and dielectric properties with mechanical characteristics are poorly known. Information on these relations is crucial for evaluation of the diagnostic potential of impedance techniques. In this study, electrical and dielectric properties, i.e. permittivity, conductivity, phase angle, loss factor, specific impedance and dissipation factor of human trabecular bone samples (n=26, harvested from the distal femur and proximal tibia) were characterized in a wide frequency range (50 Hz-5 MHz). Mechanical properties, i.e. Young's modulus, ultimate strength, yield stress, yield strain and resilience of the samples (n=20) were determined by using destructive compressive testing. Subsequently, measurements of electrical and dielectric properties were repeated after mechanical testing. The measurements were also repeated for the control samples (n=6) that were not mechanically tested. Electrical, dielectric or mechanical properties showed no significant differences between the intact femoral and tibial samples. The electrical and dielectric parameters as well as the linear correlations between the dielectric and electrical parameters with mechanical parameters were strongly frequency dependent. At the frequency of 1.2 MHz, the relative permittivity showed the strongest linear correlations with the Young's modulus (r=0.71, p<0.01, n=20) and ultimate strength (r=0.73, p<0.01, n=20). Permittivity and dissipation factor showed statistically significant changes after mechanical testing. Our results suggest that the measurements of low frequency electrical and dielectric properties may provide information on the mechanical status of trabecular bone and, possibly, may even help to diagnose bone microdamage. In the future, these measurement techniques may be further developed for use during open surgery, such as bone grafting or total hip replacement surgery.

Algorithms↗

PubMedDate not supplied

Human fibroblast migration in three-dimensional collagen gel in response to noninvasive electrical stimulus. I. Characterization of induced three-dimensional cell movement.

Cell adhesion and motility is one of the important biological processes involved in cell growth, differentiation, inflammatory response, and wound healing, and in engineered tissue constructs. Because cellular behaviors can be influenced by the local electrical environment within tissues, induced cell orientation, adhesion, and migration by exogenous electrical stimulus have been extensively examined on two-dimensional (2D) substrates. Similar cellular responses in 3D matrix have not been well documented, however. We have therefore used the 3D collagen gel as a model to characterize human fibroblast movement in response to noninvasive DC electrical stimulus. Cell movements were compared by plating the cells on 2D substrates and embedding them into the reconstituted 3D collagen gel. Our results indicate that 3D cell movement is regulated by both electrical stimulus strength and collagen concentration. For example, a small noninvasive electrical stimulus (0.1 V/cm) was found to be sufficient to induce 3D cell migration, and a collagen concentration of 0.58 mg/mL appeared to represent the optimal scaffold network environment. The same electrical stimulus did not induce significant 2D cell movement, however. Typical cell migration was best analyzed by assuming both directed and random movement and that, in response to an electrical stimulus of 0.1 V/cm, the cell migration rate was 0.23 microm/min and the random motility coefficient was 0.07 microm2/min. Because regulation of cell adhesion and migration is often desired in tissue engineering, the ability to apply physical stimulus and to control 3D cell movement may provide an alternative methodology for regulation of engineered tissue constructs.

Cell Movement↗

PubMed1997

Prevention of hypothermia by cutaneous warming with new electric blankets during abdominal surgery.

We have evaluated the efficacy of new electric warming blankets, which meet the requirements of the international standard for perioperative electrical and thermal safety, in preventing intraoperative hypothermia. We studied 18 patients undergoing abdominal surgery, allocated to one of two groups: in the control group, there was no prevention of intraoperative hypothermia (n = 8) and in the electric blanket group, two electric blankets covered the legs and upper body (n = 10). Anaesthesia duration was similar in the two groups (mean 201 (SEM 11) min), as was ambient temperature (20.5 (0.1) degrees C). Core temperature decreased during operation by 1.5 (0.1) degrees C in the control group, but only by 0.3 (0.2) degree C in the electric blanket group (P < 0.01). Five patients shivered in the control group compared with one in the electric blanket group (P < 0.05). We conclude that cutaneous warming with electric blankets was an effective means of preventing intraoperative hypothermia during prolonged abdominal surgery.

Abdomen↗

PubMed1999

Effect of polyphosphate treatment and electrical stimulation on postchill changes in quality of broiler breast meat.

The objective of this study was to assess effects of treating electrically stimulated broiler forequarters with polyphosphates after various aging periods on quality. Ninety-six mixed sex broilers were electrically stunned and slaughtered. Half the carcasses were electrically stimulated during bleeding and half were not. Forequarters were harvested immediately after chilling and after 2, 4, and 6 h postchill. Left forequarters were marinated in salt solution and right forequarters in salt solution plus sodium tripolyphosphate. After marination, the quarters were cooked. Yield and meat pH were evaluated immediately after marinating; and color, yield, and cooking loss were evaluated after cooking. Electrical stimulation resulted in a decline in muscle pH for the 0 postchill group. The pH of muscles from unstimulated and stimulated carcasses from the remainder of the postchill times were equivalent. Phosphate treatment increased pH at all postchill times. Electrical stimulation of the marinated quarters increased cooking loss and decreased yield regardless of marinade composition. Both cooking loss and yield were superior for forequarters harvested at 0 or 2 h postchill compared to those harvested at 4 or 6 h postchill. The phosphate improved moisture binding regardless of electrical treatment or time of harvest. Color values of cooked muscles were unaffected by marination time, but the phosphate-treated muscles had higher b* (yellowness) values than controls. Shear values of unstimulated carcasses that received phosphate treatment were 35% greater than those that received no phosphate treatment. When the carcasses were electrically stimulated, the toughening effect of the phosphate was eliminated.

Animals↗

PubMed2000

The influence of postmortem electrical stimulation on rigor mortis development, calpastatin activity, and tenderness in broiler and duck pectoralis.

This study was conducted to evaluate the effects of electrical stimulation (ES) on rigor mortis development, calpastatin activity, and tenderness in anatomically similar avian muscles composed primarily of either red or white muscle fibers. A total of 72 broilers and 72 White Pekin ducks were either treated with postmortem (PM) ES (450 mA) at the neck in a 1% NaCl solution for 2 s on and 1 s off for a total of 15 s or were used as nonstimulated controls. Both pectoralis muscles were harvested from the carcasses after 0.25, 1.25, and 24 h PM and analyzed for pH, inosine:adenosine ratio (R-value), sarcomere length, gravimetric fragmentation index, calpastatin activity, shear value, and cook loss. All data were analyzed within species for the effects of ES. Electrically stimulated ducks had a lower muscle pH at 0.25 and 1.25 h PM and higher R-values at 0.25 h PM compared with controls. Electrically stimulated broilers had a lower muscle pH at 1.25 h and higher R-values at 0.25 and 1.25 h PM compared with controls. Muscles of electrically stimulated broilers exhibited increased myofibrillar fragmentation at 0.25 and 1.25 h PM, whereas there was no such difference over PM time in the duck muscle. Electrical stimulation did not affect calpastatin activity in either broilers or ducks; however, the calpastatin activity of the broilers did decrease over the aging time period, whereas that of the ducks did not. Electrical stimulation decreased shear values in broilers at 1.25 h PM compared with controls; however, there was no difference in shear values of duck muscle due to ES at any sampling time. Cook loss was lower for electrically stimulated broilers at 0.25 and 1.25 h PM compared with the controls, but had no effect in the ducks. These results suggest that the red fibers of the duck pectoralis have less potential for rigor mortis acceleration and tenderization due to ES than do the white fibers of the broiler pectoralis.

Animals↗

PubMed1987

Circulatory response of digital arteries associated with electrical stimulation of calf muscle in healthy subjects.

The purpose of this study was to investigate the effects of electrical stimulation (2,500-Hz sine wave modulated at 50 bursts per second) of the posterior calf musculature on the blood circulation of an unexercised part of the body, the ipsilateral digital arteries. Intensities of electrical stimulation sufficient to produce 15% and 30% of isometric maximum voluntary contraction (MVC) of the plantar flexor muscles were used. Twenty-four healthy subjects participated in this study and were assigned either to an Experimental Group receiving electrical stimulation (n = 13) or to a Control Group not receiving electrical stimulation (n = 11). Analysis of data revealed significant differences in finger blood flow when the calf musculature was stimulated electrically. We found significant differences in blood flow of the finger when torques produced by electrical stimulation of the calf musculature were raised to 15% and 30% of MVC. The results of the study indicate that blood flow in the ipsilateral finger decreases significantly when the posterior calf musculature is exercised artificially with electrical stimulation bursts.

Adult↗

PubMed1994

Quadriceps femoris muscle resistance to fatigue using an electrically elicited fatigue test following intense endurance exercise training.

BACKGROUND AND PURPOSE: Electrical stimulation has been used to assess skeletal muscle resistance to fatigue. The purpose of this study was to test the hypothesis that 12 weeks of intense endurance exercise training on a bicycle ergometer would reduce the percentage of decline in quadriceps femoris muscle torque during an electrically elicited fatigue test. SUBJECTS AND METHODS: Eleven nondisabled subjects performed 12 weeks of high-intensity endurance exercise training, and 6 subjects served as controls and did not exercise. Two electrically elicited fatigue tests, one with and one without prior voluntary fatiguing exercise, were administered to each subject before and after the 12-week training period. RESULTS: The percentage of decline in peak torque of the quadriceps femoris muscle over 50 electrically elicited muscle contractions did not change as a result of endurance exercise training, despite significant improvements in maximal oxygen consumption and quadriceps femoris muscle endurance. The recovery of maximal isometric torque immediately after exhausting voluntary exercise followed by electrical stimulation was significantly greater after 12 weeks of intense exercise training. CONCLUSION AND DISCUSSION: The percentage of decline in peak torque during an electrically elicited fatigue test does not detect improvements in quadriceps femoris muscle endurance induced by endurance exercise training. The percentage of initial torque recovered immediately after fatiguing exercise, however, is improved by endurance training. [Sinacore Dr, Jacobson RB, Delitto A. Quadriceps femoris muscle resistance to fatigue using an electrically elicited fatigue test following intense endurance exercise training.

Adult↗

PubMed1999

A comparison of myogenic motor evoked responses to electrical and magnetic transcranial stimulation during nitrous oxide/opioid anesthesia.

UNLABELLED: Transcranial motor evoked potentials (tc-MEPs) are used to monitor spinal cord integrity intraoperatively. We compared myogenic motor evoked responses with electrical and magnetic transcranial stimuli during nitrous oxide/opioid anesthesia. In 11 patients undergoing spinal surgery, anesthesia was induced with i.v. etomidate 0.3 mg/kg and sufentanil 1.5 microg/kg and was maintained with sufentanil 0.5 microg x kg(-1) x h(-1) and N2O 50% in oxygen. Muscle relaxation was kept at 25% of control with i.v. vecuronium. Electrical stimulation was accomplished with a transcranial stimulator set at maximal output (1200 V). Magnetic transcranial stimulation was accomplished with a transcranial stimulator set at maximal output (2 T). Just before skin incision, triplicate responses to single stimuli with both modes of cortical stimulation were randomly recorded from the tibialis anterior muscles. Amplitudes and latencies were compared using the Wilcoxon signed rank test. Bilateral tc-MEP responses were obtained in every patient with electrical stimulation. Magnetic stimulation evoked only unilateral responses in two patients. With electrical stimulation, the median tc-MEP amplitude was 401 microV (range 145-1145 microV), and latency was 32.8 +/- 2.3 ms. With magnetic stimulation, the tc-MEP amplitude was 287 microV (range 64-506 microV) (P < 0.05), and the latency was 34.7 +/- 2.1 ms (P < 0.05). We conclude that myogenic responses to magnetic transcranial stimulation are more sensitive to anesthetic-induced motoneural depression compared with those elicited by electrical transcranial stimulation. IMPLICATIONS: Transcranial motor evoked potentials are used to monitor spinal cord integrity intraoperatively. We compared the relative efficacy of electrical and magnetic transcranial stimuli in anesthetized patients. It seems that myogenic responses to magnetic transcranial stimulation are more sensitive to anesthetic-induced motoneural depression compared with electrical transcranial stimulation.

Anesthesia, General↗

PubMed2002

Electrical stimulation enhances the survival of axotomized retinal ganglion cells in vivo.

In view of recent reports on the survival promotion of damaged spiral ganglion cells and motoneurons by electrical stimulation, we hypothesized that an electrical stimulation of the cut optic nerve (ON) may promote the survival of axotomized retinal ganglion cells (RGCs) in vivo. To test this hypothesis, we examined 1 week after ON transection the RGC densities in the retinas with or without electrical stimulation. The densities of surviving RGCs in the retinas with the electrical stimulation increased as compared with those without the electrical stimulation. We concluded that electrical stimulation of the ON enhances the survival of axotomized RGCs in vivo, probably due to electrical activation of their soma.

Animals↗