Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ELECTRICITY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed2002

Transcutaneous electrical stimulation of an auricular acupuncture point decreases anesthetic requirement.

BACKGROUND: German anesthesiologists have long used transcutaneous electrical stimulation of an acupuncture point near the tragus to reduce anesthetic requirement in unblinded and uncontrolled trials. This is known as auricular electrically stimulated analgesia. The authors therefore tested the hypothesis that auricular electrically stimulated analgesia reduces anesthetic requirement. METHODS: In a randomized, double-blind, crossover trial, volunteers were anesthetized twice with desflurane. Electrical stimulation of an auricular acupuncture point in the vicinity of the tragus was used on 1 randomly assigned day, and no electrical stimulation of the same point was used on the other study day. Treatment consisted of bilateral electrical stimulation of the lateralization control point, 3 cm anterior to the tragus. The 10-mA current was set to 299 Hz on the dominant side of the face and to 149 Hz on the contralateral side. Anesthetic requirement was determined by the Dixon up-and-down method and was defined by the average desflurane concentration required to prevent purposeful movement of the extremities in response to noxious electrical stimulation. RESULTS: Ten men and 10 women completed the protocol. Electrical stimulation of the lateralization control point reduced anesthetic requirement by 11 +/- 7% (P < 0.001), with the reduction being similar in women and men. Women required more desflurane to prevent movement on the control day than the men (5.5 +/- 1.0 vs. 4.6 +/- 0.6 vol%; P = 0.028). CONCLUSION: This double-blinded trial with an objective outcome demonstrates that electrical stimulation of the lateralization control point significantly reduces anesthetic requirement.

Acupuncture Points↗
PubMed2004

Manual versus electric vacuum aspiration for early first-trimester abortion: a controlled study of complication rates.

OBJECTIVE: Manual vacuum aspiration is an alternative to electric suction curettage for first-trimester elective abortion. Although many studies have demonstrated that manual vacuum aspiration is safer than sharp curettage for abortion, only a few studies have directly compared it with electric suction curettage. These studies proved the methods to be equally effective and acceptable but were too small to adequately compare safety. We compared immediate complication rates for abortions performed by manual and electric vacuum aspiration. METHODS: We conducted a retrospective cohort analysis of all women undergoing elective abortion at up to 10 weeks' gestation at San Francisco General Hospital over a 3.5-year period. A total of 1726 procedures were included: 1002 manual and 724 electric vacuum aspirations. Clinical data were collected from medical records. Rates of uterine reaspiration and other immediate complications occurring at our institution were compared. RESULTS: We found no difference in the rate of uterine reaspiration after abortions performed with the manual or electric suction device (2.2% versus 1.7%, respectively, P =.43). We had 80% statistical power to detect a 2% difference in uterine reaspiration rates with an microa error of.05. Overall major complication rates were 2.5% with manual and 2.1% with electric suction curettage, P =.56. Multivariable regression analyses controlling for potential confounders showed no difference in uterine reaspiration rates (electric odds ratio [OR] = 0.71, 95% confidence interval [CI] 0.32, 1.6) or overall complications (electric OR = 0.81, 95% CI 0.40, 1.7). CONCLUSION: Manual vacuum aspiration is as safe as electric suction curettage for abortions at up to 10 weeks' gestation. Expanded use in an office setting might increase abortion access.

Abortion, Induced↗
PubMed1993

Patterned neuronal attachment and outgrowth on surface modified, electrically charged fluoropolymer substrates.

Fluorinated ethylenepropylene copolymer (FEP) and polyvinylidene fluoride (PVDF) can generate static and transient electrical charges, respectively, after bulk molecular rearrangements induced by electrical charging techniques. Neurons cultured on electrically active FEP and PVDF show increased levels of nerve fiber outgrowth compared to electrically neutral material. The purpose of the present study was to determine if the addition of charged surface groups to the surfaces of FEP and PVDF would modify the influence of bulk electrical charges on cultured neurons. Mouse neuroblastoma (Nb2a) cells were cultured on electrically charged and uncharged FEP and PVDF substrates with covalently modified surfaces containing hydroxyl (OH) and amine (NH2) groups. Surface chemical modification was performed on the entire surface or in discrete striped regions. Nb2a cells cultured on electrically active FEP and PVDF showed greater levels of differentiation than cells on electrically neutral substrates. The presence of NH2 groups attenuated these responses in serum-containing media. Cells attached to NH2 rich surfaces generally displayed a flatter morphology and tended to remain attached for longer time periods. Cells cultured on stripe-modified substrates in serum-containing media showed a strong preferential attachment to modified regions, especially on NH2 stripes. In summary, bulk electrical charges are more important than surface charges in stimulating Nb2a cell differentiation. Surface groups serve to modulate neuronal morphology and confer specific attachment promoting properties in serum-containing media. The development of an optimal neuronal regeneration template may require the incorporation of specific bulk and surface properties.

Animals↗
PubMed2005

Molecular shielding of electric field complex dissociation.

We have previously demonstrated the ability of electric fields to dissociate ascorbate and catecholamines and shown that the electric field generated by cell membranes is sufficient to produce dissociation of these complexes up to 8 nm from the cell membrane. We show here that this process is applicable to a wide range of biological complexes including small molecules (norepinephrine-morphine sulfate), protein-protein complexes (insulin-glucagon), and small molecule-protein complexes (epinephrine-bovine serum albumin). The extrapolation of the slope of the electric field dependence to zero electric field can be used to estimate the log of the dissociation constant (K(D)) of a complex and, by multiplying the log(K(D)) by -2.303RT, the association energy (E) of the complex. The slope of the electric field dependence is inversely related to the molecular radii, with the best fit of the slope related to E*(1/r1 + 1/r2), where r is the estimated radius of each molecule in the complementary pair. This indicates that the binding site of the pair is shielded by the remaining parts of the molecules, and the larger the molecule the greater the shielding. When the slope of the electric field dependence goes to 0 as r goes to infinity and 1/r goes to 0, the molecular shielding constant is 7.04 x 10(-8) cm2/V. Very large complexes will be minimally affected by the electric field due to molecular shielding and reduced electric field as their radius restricts approach to the membrane. Large protein receptors will deflect the membrane electric field and allow agonist binding.

Animals↗
PubMed1982

The effects of videotape modeling and daily feedback on residential electricity conservation, home temperature and humidity, perceived comfort, and clothing worn: Winter and summer.

Two studies were conducted in all-electric townhouses and apartments in the winter (N = 83) and summer (N = 54) to ascertain how energy conservation strategies focusing on thermostat change and set-backs and other low-cost/no-cost approaches would affect overall electricity use and electricity used for heating and cooling, the home thermal environment, the perceived comfort of participants, and clothing that was worn. The studies assessed the effectiveness of videotape modeling programs that demonstrated these conservation strategies when used alone or combined with daily feedback on electricity use. In the winter, the results indicated that videotape modeling and/or feedback were effective relative to baseline and to a control group in reducing overall electricity use by about 15% and electricity used for heating by about 25%. Hygrothermographs, which accurately and continuously recorded temperature and humidity in the homes, indicated that participants were able to live with no reported loss in comfort and no change in attire at a mean temperature of about 62 degrees F when home and about 59 degrees F when asleep. The results were highly discrepant with prior laboratory studies indicating comfort at 75 degrees F with the insulation value of the clothing worn by participants in this study. In the summer, a combination of strategies designed to keep a home cool with minimal or no air conditioning, in conjunction with videotape modeling and/or daily feedback, resulted in overall electricity reductions of about 15% with reductions on electricity for cooling of about 34%, but with feedback, and feedback and modeling more effective than modeling alone. Despite these electricity savings, hygrothermograph recordings indicated minimal temperature change in the homes, with no change in perceived comfort or clothing worn. The results are discussed in terms of discrepancies with laboratory studies, optimal combinations of video-media and personal contact to promote behavior change, and energy policies that may be mislabeled as sacrificial and underestimate the effectiveness of conservation strategies such as those investigated in these studies.

Journal Article↗
PubMed2004

Comparison of transcranial electric motor and somatosensory evoked potential monitoring during cervical spine surgery.

BACKGROUND: There has been little enthusiasm for somatosensory evoked potential monitoring in cervical spine surgery as a result, in part, of the increased risk of motor tract injury at this level, to which somatosensory monitoring may be insensitive. Transcranial electric motor evoked potential monitoring allows assessment of the motor tracts; therefore, we compared transcranial electric motor evoked potential and somatosensory evoked potential monitoring during cervical spine surgery to determine the temporal relationship between the changes in the potentials demonstrated by each type of monitoring and neurological sequelae and to identify patient-related and surgical factors associated with intraoperative neurophysiological changes. METHODS: Somatosensory evoked potential and transcranial electric motor evoked potential data recorded for 427 patients undergoing anterior or posterior cervical spine surgery between January 1999 and March 2001 were analyzed. All patients who showed substantial (at least 60%) or complete unilateral or bilateral amplitude loss, for at least ten minutes, during the transcranial electric motor evoked potential and/or somatosensory evoked potential monitoring were identified. RESULTS: Twelve of the 427 patients demonstrated substantial or complete loss of amplitude of the transcranial electric motor evoked potentials. Ten of those patients had complete reversal of the loss following prompt intraoperative intervention, whereas two awoke with a new motor deficit. Somatosensory evoked potential monitoring failed to identify any change in one of the two patients, and the change in the somatosensory evoked potentials lagged behind the change in the transcranial electric motor evoked potentials by thirty-three minutes in the other. No patient showed loss of amplitude of the somatosensory evoked potentials in the absence of changes in the transcranial electric motor evoked potentials. Transcranial electric motor evoked potential monitoring was 100% sensitive and 100% specific, whereas somatosensory evoked potential monitoring was only 25% sensitive; it was, however, 100% specific. CONCLUSIONS: Transcranial electric motor evoked potential monitoring appears to be superior to conventional somatosensory evoked potential monitoring for identifying evolving motor tract injury during cervical spine surgery. Surgeons should strongly consider using this modality when operating on patients with cervical spondylotic myelopathy in general and on those with ossification of the posterior longitudinal ligament in particular.

Cervical Vertebrae↗
PubMed1985

Fleischner lecture. Biokinetic impacts on structure and imaging of the lung: the concept of biologically closed electric circuits.

The corona complex of the lung is a collection of radiographic features surrounding a pulmonary mass. Each of its 12 components may be explained by a recently described subset of biologically closed electric circuits, the vascular-interstitial closed electric circuit (VICC) system. This system is activated both by normal metabolism of tissue and by local degrading processes, such as spontaneous necrosis or hemorrhage, that lead to local electrochemical polarization of a lesion in relation to surrounding noninjured tissue. Ions, cells, and water are transported electrically in the VICC system, leading to the development of the corona complex. The VICC system is conceived to exist with the walls of arteries and veins functioning as insulators around the electrically conducting medium of blood, the plasma. Blood vessels therefore connect electrically the injured and noninjured tissues. At the capillary level, electric junctions connect plasma and interstitial fluid, which functions as an electrical conductor comparable to blood plasma. The interstitial fluid therefore completes the circuit. The VICC system can be regarded as an additional circulatory system for selective electrogenic transports, coupled directly to the mechanical circulation of blood and lymph. The injury potential represents an important energetic factor in the activation of the VICC system. It is a slowly fluctuating, attenuating, electrochemical potential inducing ebb and flow of time-dependent anionic and cationic transports. The corona structures are special effects of the healing of injured tissue. The 12 radiologic signs of the corona complex have each been produced experimentally in vitro in animals and in vivo in humans during electrochemical treatment of cancers. The "A" zone is characterized radiographically by radiolucency around an electrically polarizing focal lesion. Peripheral to the A zone, a "B" zone is seen as a radiopaque region. The A and B zones are predominantly the result of an electroosmotic outflow of water from a lesion during its electropositive phase. At the interface between the A and B zones, small arches sometimes form an arcade. This configuration develops when the polarizing lesion has small protrusions at its surface. As a result of electrical edge enhancement, various elements of the interstitial tissue are transformed into radiating fibrous structures. They grow out at right angles to the surface of the lesion and serve as supporting columns for the arches. When necrotic material from a tumor is evacuated through a bronchus, ensuing collapse of the tumor will displace those radiating structures already produced.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed2005

Deep brain stimulation in movement disorders: stereotactic coregistration of two-dimensional electrical field modeling and magnetic resonance imaging.

OBJECT: Adjusting electrical parameters used in deep brain stimulation (DBS) for dystonia remains time consuming and is currently based on clinical observation alone. The goal of this study was to visualize electrical parameters around the electrode, to correlate these parameters with the anatomy of the globus pallidus internus (GPI), and to study the relationship between the volume of stimulated tissue and the electrical parameter settings. METHODS: The authors developed a computer-assisted methodological model for visualizing electrical parameters (the isopotential and the isoelectric field magnitude), with reference to the stereotactic target, for different stimulation settings (monopolar and bipolar) applied during DBS. Electrical field values were correlated with the anatomy of the GPI, which was determined by performing stereotactic magnetic resonance imaging in one reference patient. By using this method it is possible to compare potential and electrical field distributions for different stimulation modes. In monopolar and bipolar stimulation, the shape and distribution of the potential and electrical field are different and depend on the stimulation voltage. Distributions visualized for patient-specific parameters can be subsequently correlated with anatomical information. The application of this method to one patient demonstrated that the 0.2-V/ mm isofield line fits best with the lateral GPI borders at the level of the stimulated contacts. CONCLUSIONS: The electrical field is a crucial parameter because it is assumed to be responsible for triggering action potentials. Electrical field visualization allows the calculation of the stimulated volume for a given isoline. Its application to an entire series of patients may help determine a threshold for obtaining a therapeutic effect, which is currently unknown, and consequently may aid in optimizing parameter settings in individual patients.

Adolescent↗
PubMed1997

Gastric electrical dysrhythmias and delayed gastric emptying in gastroesophageal reflux disease.

OBJECTIVE: Deranged gastric motility and delayed gastric emptying are commonly implicated in the pathophysiology of gastroesophageal reflux disease. We measured gastric electrical activity and gastric emptying time of a solid-liquid meal by electrogastrography and antral ultrasound, respectively, in 42 patients with gastroesophageal reflux disease (age 7.4 +/- 1.6 yr). METHODS: Based on endoscopy and histology of the esophageal mucosa, reflux disease was moderate in 20 patients and severe in 22. Electrogastrography was measured by placing two Ag-AgCl electrodes on the epigastric skin, signals were digitized and fed into a personal computer, and data were obtained by running spectrum analysis. The electrogastrographic variables calculated were: 1) percent of electrical dysrhythmias and normal electrical rhythm (bradygastria or 0.5-2.0 cycles/min, tachygastria or 4.0-9.0 cycles/min; normal rhythm is 2.0-4.0 cycles/min); 2) fed:fasting ratio of dominant electrogastrographic power; 3) fed:fasting ratio of the dominant frequency instability coefficient. Gastric emptying time and electrical activity results were compared with those measured in 15 controls (7.1 +/- 1.7 yr). RESULTS: Dysrhythmic episodes were more common in both groups of patients than in controls (p < 0.01); furthermore, gastric emptying time was significantly more delayed in patients than in controls (p < 0.01). Children with severe gastroesophageal reflux were distinguished from those with moderate disease for post-feeding gastric electrical abnormalities consisting of reduced electrogastrographic dominant power and increased frequency variability (p < 0.01), as well as for a more prolonged gastric emptying time (p < 0.05). Prevalence of both normal electrical rhythm and dysrhythmias did not discriminate the two groups of patients. In patients and in controls, a significant inverse correlation between fed electrogastrographic power and gastric emptying time was found (r -0.88, p < 0.01). CONCLUSIONS: Fed gastric electrical abnormalities consisting of reduced dominant power and increased variability of the electrical dominant frequency are detected in patients with severe gastroesophageal reflux disease and are associated with delayed gastric emptying. Gastric electrical dysrhythmias may be included among the pathogenetic components of gastroesophageal reflux disease.

Child↗
PubMed1986

Androgen binding in the brain and electric organ of a mormyrid fish.

The mormyrid fish of Africa produce a weak electric pulse called an Electric Organ Discharge (EOD) that functions in electrical guidance and communication. The EOD waveform describes the appearance of a single pulse which is produced by the electric organ's excitable cells, the electrocytes. For some species, there is a sex difference in the appearance and duration of the EOD waveform, which is under the control of gonadal steroid hormones. We now show, using biochemical techniques, that the steroid-sensitivity of the myogenic electric organ correlates with the presence of comparatively high levels of androgen-binding activity in the cytosol of electrocytes. The EOD rhythm describes the rate at which the electric organ fires and is under the control of a central electromotor pathway. Sex differences have also been described for the EOD rhythm. Using steroid autoradiographic techniques, we found uptake of tritium-labelled dihydrotestosterone (3H-DHT) by cells within the reticular formation that lie adjacent to the medullary 'relay nucleus' which innervates the spinal electromotoneurons that excite the electric organ. However, no DHT-binding was observed in the relay or electromotor nuclei. Steroid-concentrating cells were also found in several other brainstem regions, the hypothalamus, and the thalamus. In particular, a group of DHT-concentrating, motoneuron-like cells were observed in the caudal medulla and were identified as a swimbladder or sonic motor nucleus. The biochemical data suggest that the electric organ has evolved a sensitivity to gonadal steroid hormones that may underlie the development of known sex differences in the EOD waveform. The autoradiographic results suggest that if steroids do affect the development of sex differences in the EOD rhythm, it is at some level removed from known spinal and medullary electromotor nuclei.

Androgens↗
PubMed2006

Peripheral electrosensory imaging by weakly electric fish.

Different species have developed different solutions to the problem of constructing a representation of the environment from sensory images projected onto sensory surfaces. Comprehension of how these images are formed is an essential first step in understanding the representation of external reality by a given sensory system. Modeling of the electrical sensory images of objects began with the discovery of electroreception and continues to provide general insights into the mechanisms of imaging. Progress in electric image research has made it possible to establish the physical basis of electric imaging, as well as methods to accurately predict the electric images of objects alone and as a part of a natural electric scene. In this review, we show the following. (1) The internal low resistance of the fish's body shapes the image in two different ways: by funneling the current generated by the electric organ to the sensory surface, it increases the fields rostrally, thus enhancing the perturbation produced by nearby objects; and by increasing the projected image. (2) The electric fish's self-generated currents are modified by capacitive objects in a distinctive manner. These modulations can be detected by different receptor types, yielding the possibility of "electric color." (3) The effects of different objects in a scene interact with each other, generating an image that is different from the simple addition of the images of individual objects, thus causing strong contextual effects.

Animals↗
PubMed2001

Plasticity of the electric organ discharge waveform of male Brachyhypopomus pinnicaudatus. II. Social effects.

Many electric fish produce sexually dimorphic electric organ discharges. Although electric organ discharges are comprised of action potentials, those of the Gymnotiform family Hypopomidae show significant plasticity in response to stress and time of day. We show here that male Brachyhypopomus pinnicaudatus (Hopkins 1991), adjusts the degree of sexual dimorphism in its electric organ discharge depending on immediate social conditions. Three to five days of isolation resulted in gradual decrease of two sexually dimorphic waveform characters: duration and amplitude. Introduction of a second fish to the experimental tank restored electric organ discharge duration and amplitude. Duration recovered quicker than amplitude, and both recovered faster in the presence of males than females. In studies of other electric fish species, treatment with steroid sex hormones have taken several days to increase sexual dimorphism in the electric organ discharge. The socially induced changes seen in this study are initiated too quickly to involve classic steroid action of genomic transcription and thus may depend on another mechanism. Socially induced regulation of the male's electric organ discharge waveform is consistent with the compromises in signaling strategy shown by other taxa with costly sexual advertisement signals.

Animals↗
PubMed1988

Role of cell membrane rupture in the pathogenesis of electrical trauma.

Heating due to current flow may not always be the primary cause of tissue damage in electrical injury. We have demonstrated that electric field strengths relevant to the clinical electrical injury problem are capable of permanently disrupting isolated skeletal muscle cells and altering the electrical properties of intact skeletal muscle in the absence of Joule heating effects. The field strengths used in these experiments are theoretically representative of fields at sites distant from the surface entry and exit points in many cases of electrical injury. These results provide further evidence that cell membrane disruption by large induced transmembrane potentials may explain the changes in the electrical properties of muscle observed in experimental electrical trauma (M. Chilbert, et al., J. Trauma 25: 209, 1985) and thus may contribute significantly to the extensive tissue destruction associated with electrical trauma.

Animals↗
PubMed1991

Measurement of the electric field induced into inhomogeneous volume conductors by magnetic coils: application to human spinal neurogeometry.

We measured the electric fields induced by round and figure "8" magnetic coils (MCs) in homogeneous and inhomogeneous volume conductors. In homogeneous media, the round MC held tangential (i.e., flat) to the volume conductor induced an annular electric field. When the round MC was held on-edge (i.e., orthogonal) to the volume conductor, the induced electric field consisted of two loops mainly parallel to the surface of the volume conductor and which approximated each other directly under the contacting edge of the MC. The tangentially oriented figure "8" MC similarly induced two electric field loops which approximated one another maximally under the region of the junction in its long axis. In a complex inhomogeneous volume conductor, such as a segment of human cervical-thoracic vertebral spine located eccentrically within a large cylindrical tank and submerged in isotonic saline, the direction of electric fields within the spinal canal and across the intervertebral neuroforamina was similar to that observed in the homogeneous volume conductor. However, in and near a single neuroforamen, the electric field and especially its first spatial derivative were markedly elevated compared to that recorded within the long central axis of the vertebral canal. Motor unit and compound muscle action potentials elicited in limb muscles by MC stimulation of human cervical spine confirmed predictions derived from the physical model. The predictions included: (1) absence of spinal cord stimulation compared to relative ease of nerve root stimulation by current that is most likely concentrated at the neuroforamina. When stimulating current is directed towards the periphery, the most likely low threshold site of stimulation is inferred to be just distal to the neuroforamina. It is emphasized that with supramaximal stimulation, more distal sites of excitation may occur; (2) invariant latency shifts at threshold intensities when moving the MC along the rostrocaudal axis of the cervical vertebral column; (3) significant effect (on motor unit activation thresholds) of the direction of induced current flow across the neuroforamina; (4) reduced stimulation when the targeted nerve roots are close to the null point of the electric field, i.e., between locations of high electric field intensity, of opposite polarity; and (5) relatively focal nerve root stimulation by the junction of a transversely orientated figure "8" MC, i.e., parallel to the nerve roots.

Adult↗
PubMed2006

Sodium channel genes and the evolution of diversity in communication signals of electric fishes: convergent molecular evolution.

We investigated whether the evolution of electric organs and electric signal diversity in two independently evolved lineages of electric fishes was accompanied by convergent changes on the molecular level. We found that a sodium channel gene (Na(v)1.4a) that is expressed in muscle in nonelectric fishes has lost its expression in muscle and is expressed instead in the evolutionarily novel electric organ in both lineages of electric fishes. This gene appears to be evolving under positive selection in both lineages, facilitated by its restricted expression in the electric organ. This view is reinforced by the lack of evidence for selection on this gene in one electric species in which expression of this gene is retained in muscle. Amino acid replacements occur convergently in domains that influence channel inactivation, a key trait for shaping electric communication signals. Some amino acid replacements occur at or adjacent to sites at which disease-causing mutations have been mapped in human sodium channel genes, emphasizing that these replacements occur in functionally important domains. Selection appears to have acted on the final step in channel inactivation, but complementarily on the inactivation "ball" in one lineage, and its receptor site in the other lineage. Thus, changes in the expression and sequence of the same gene are associated with the independent evolution of signal complexity.

Amino Acid Sequence↗
PubMed2003

Analgesic effects of transcutaneous electrical nerve stimulation and interferential currents on heat pain in healthy subjects.

This study examined whether transcutaneous electrical nerve stimulation or interferential current was more effective in reducing experimentally induced heat pain. Forty-eight young healthy subjects were randomly divided into the following groups: (i) transcutaneous electrical nerve stimulation; (ii) interferential current; and (iii) no stimulation. A multi-function electrical stimulator was used to generate the transcutaneous electrical nerve stimulation or interferential current. A thermal sensory analyser was used to record the heat pain threshold. The stimulation lasted for 30 minutes and the heat pain thresholds were measured before, during and after the stimulation. Transcutaneous electrical nerve stimulation (p = 0.003) and interferential current (p = 0.004) significantly elevated the heat pain threshold, but "no stimulation" did not. The thresholds of the transcutaneous electrical nerve stimulation and interferential current groups were significantly higher than that of the control group 30 minutes into the stimulation (p = 0.017). Both transcutaneous electrical nerve stimulation and interferential current increased the heat pain threshold to a similar extent during stimulation. However, the post-stimulation effect of interferential current lasted longer than that of transcutaneous electrical nerve stimulation.

Adolescent↗
PubMed2003

Electrical and dielectric properties of bovine trabecular bone--relationships with mechanical properties and mineral density.

Interrelationships of trabecular bone electrical and dielectric properties with mechanical characteristics and density are poorly known. While electrical stimulation is used for healing fractures, better understanding of these relations has clinical importance. Furthermore, earlier studies have suggested that bone electrical and dielectric properties depend on the bone density and could, therefore, be used to predict bone strength. To clarify these issues, volumetric bone mineral density (BMDvol), electrical and dielectric as well as mechanical properties were determined from 40 cylindrical plugs of bovine trabecular bone. Phase angle, relative permittivity, loss factor and conductivity of wet bovine trabecular bone were correlated with Young's modulus, yield stress, ultimate strength, resilience and BMDvol. The reproducibility of in vitro electrical and dielectric measurements was excellent (standardized coefficient of variation less than 1%, for all parameters), especially at frequencies higher than 1 kHz. Correlations of electrical and dielectric parameters with the bone mechanical properties or density were frequency-dependent. The relative permittivity showed the strongest linear correlations with mechanical parameters (r > 0.547, p < 0.01, n = 40, at 50 kHz) and with BMDvol (r = 0.866, p < 0.01, n = 40, at 50 kHz). In general, linear correlations between relative permittivity and mechanical properties or BMDvol were highest at frequencies over 6 kHz. In addition, a significant site-dependent variation of electrical and dielectric characteristics, mechanical properties and BMDvol was revealed in bovine femur (p < 0.05, Kruskall-Wallis H-test). Based on the present results, we conclude that the measurement of electrical and dielectric properties provides quantitative information that is related to bone quantity and quality.

Animals↗
PubMed1991

Sex recognition by electric cues in a sound-producing mormyrid fish, Pollimyrus isidori.

This paper evaluates the role of electric cues in the sex recognition behavior of an African electric fish, Polimyrus isidori, during courtship behavior observed in the laboratory. I examined the importance of the electric organ discharge (EOD: waveform of the stereotyped electric organ discharge) and the sequence of pulse intervals (SPI: temporal pattern formed by sequences inter-EOD intervals) experimentally by presenting caged fishes, and electric playbacks (models) to male residents. In this species males court females with sounds, and I used this sonic behavior to measure sex recognition. Resident males produced many more grunt sounds when females were introduced onto their territories, compared with caged males, revealing that residents discriminated the sex of the caged fish. Response rates were correlated with characteristic patterns in the SPI of the introduced fish, suggesting that discrimination was based on electric cues. Moreover, I noted several significant sex differences in the SPIs of caged fishes. Residents also discriminated between electric signals from female and male fishes, played to them through electrodes, indicating that electric cues alone were sufficient for sex recognition. An ANOVA was used to ascertain the role of the SPI and the EOD, by analyzing responses to natural female and male models, as well as responses to male EODs combined with female SPIs, and to female EODs combined with male SPIs (hybrid models). I found that discriminating residents used SPI cues alone, with no dependence on the EOD. Taken together with new data showing that females generate a highly regular SPI during natural courtship encounters with singing males, these result show that SPIs are important in sex recognition in P. isidori.

Agonistic Behavior↗