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PubMed2005

Oscillatory transverse electric field enhances mass transfer and protein capacity in ion-exchange electrochromatography.

Ion-exchange electrochromatography with an oscillatory electric field perpendicular to mobile-phase flow driven by pressure (pIEEC) was developed with a column design of rectangle cross-section. The effect of electric field strength on the dynamic binding capacity (DBC) was examined by frontal analysis of bovine serum albumin (BSA) adsorption to the packed beds of DEAE Sepharose FF in Tris-glycine buffer (pH 8.2). It was shown that the DBC at 10% breakthrough (Q(10)) in the pIEEC increased linearly with increasing the electric field strength. For example, with a packed-bed height of 15mm and electric potential gradient of 38V/cm, Q(10) increased four times over that in normal ion-exchange chromatography. So, the transverse electric field has created significant electro-kinetic mass transports (electroosmosis and electrophoresis) that intensified exterior liquid-film and intraparticle mass transfers, leading to the increased protein binding capacity. Due to the increased capacity in the pIEEC, partial resolution of BSA and IgG under an overload condition was realized without any process optimization. The results have revealed that an electric potential gradient of 20V/cm was enough to greatly enhance the DBC in the pIEEC, and when necessary, high electric field strength can be realized with a low applied voltage because the side distance of the column is usually an order of magnitude smaller than its height. The use of low voltage to carry out electrochromatography is a significant advantage of the pIEEC over conventional electrochromatography with axial electric field.

Adsorption↗
PubMed2005

Transthoracic electrical bioimpedance: a non-invasive technique for the evaluation of the haemodynamic alterations in patients with liver cirrhosis.

BACKGROUND/AIM: Transthoracic electrical bioimpedance is a non-invasive technique for the evaluation of systemic haemodynamics. Compared to Doppler ultrasound, it has the advantage of being operator-independent, providing continuous monitoring and being less influenced by postural changes. Until now, transthoracic electrical bioimpedance has been applied to a very limited extent in liver cirrhosis. We, therefore, aimed to compare transthoracic electrical bioimpedance and echocardiography in the assessment of haemodynamic status in cirrhotic patients. PATIENTS/METHODS: Thirteen patients with compensated cirrhosis, 10 patients with cirrhosis and ascites and 12 controls were enrolled. Haemodynamic parameters (stroke volume, cardiac output, heart rate, mean arterial pressure and vascular peripheral resistance) were assessed simultaneously by transthoracic electrical bioimpedance monitoring with BioZ.com for at least 10 min and Doppler ultrasound. RESULTS: The absolute mean values of haemodynamic parameters obtained by the two techniques were quite similar in all groups; furthermore, a good agreement between transthoracic electrical bioimpedance and echocardiography measurements was found for all the parameters. Finally, transthoracic electrical bioimpedance proved easy to employ and provided continuous real-time monitoring of cardio-circulatory variations. CONCLUSIONS: The present study showed a significant correlation between transthoracic electrical bioimpedance and echocardiography in the assessment of systemic haemodynamics in patients with cirrhosis, supporting the employment of transthoracic electrical bioimpedance in pathophysiological studies requiring real-time continuous monitoring of haemodynamic parameters.

Adult↗
PubMed2005

Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains.

This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.

Action Potentials↗
PubMed2006

Influence of temperature on the electrical conductivity of leachate from municipal solid waste.

A bioreactor landfill is designed to manage municipal solid waste, through accelerated waste biodegradation, and stabilisation of the process by means of the controlled addition of liquid, i.e. leachate recirculation. The measurement of electrical resistivity by Electrical Resistivity Tomography (ERT) allows to monitor water content present in the bioreactors. Variations in electrical resistivity are linked to variations in moisture content and temperature. In order to overcome this ambiguity, two laboratory experiments were carried out to establish a relationship between temperature and electrical conductivity: the first set of measurements was made for leachate alone, whereas the second set was made with two different granular media saturated with leachate. Both experiments confirm a well known increase in conductivity of about 2% degrees C(-1). However, higher suspended matter concentrations lead to a lower dependence of electrical conductivity on temperature. Furthermore, for various porous media saturated with an identical leachate, the higher the specific surface of the granular matrix, the lower the effective bulk electrical conductivity. These observations show that a correct understanding of the electrical properties of liquids requires the nature and (in particular) the size of the electrical charge carriers to be taken into account.

Bioreactors↗
PubMed2006

Sex differences in the responses of spinal wide-dynamic range neurons to subcutaneous formalin and in the effects of different frequencies of conditioning electrical stimulation.

The purpose of this study was to investigate sex-related differences in nociception elicited by s.c. injection of different concentrations (1-5%) of formalin. S.c. formalin-induced biphasic (early and late phases) persistent nociception was assessed by extracellularly recording the spontaneous activities of single spinal dorsal horn wide-dynamic range neurons in anesthetized male and female rats. The nociceptive responses of the dorsal horn wide-dynamic range neurons following s.c. injection of 5%, but not 1% and 2.5%, formalin in female rats were significantly stronger than the responses obtained in male rats. However, these concentration-dependent differences with respect to different sexes existed only in the late, but not the early, phase of formalin-induced nociception in intact, not spinal rats. The 5% formalin-induced late phase nociception in male rats was significantly depressed by 15 min of repeated conditioning electrical stimulation at a frequency of 5 Hz as well as 50 Hz during and after the period of conditioning electrical stimulation (intensity: 1 mA; pulse duration: 1 ms). In contrast, the inhibitory effect of 50 Hz conditioning electrical stimulation on the 5% formalin-elicited late phase response in female rats was markedly greater in magnitude and longer in duration than that of 5 Hz conditioning electrical stimulation. No significant depressive effects of 5 Hz conditioning electrical stimulation on formalin-induced nociception were found in female rats, indicating that the distinct effects of conditioning electrical stimulation at different frequencies are different in animals of opposite sexes. In conclusion, s.c. administration of different concentrations of formalin shows a distinct sex-related difference in its late tonic nociception of spinal nociceptive sensory neurons. Sex differences in formalin-induced tonic nociception are stimulus intensity dependent and related to the modulation from the supraspinal regions. S.c. formalin-induced late phase nociception in female rats is only sensitive to depression at a frequency of 50 Hz, but not 5 Hz, of conditioning electrical stimulation. This suggests that the involvement of the central mechanisms in the antinociceptive effects of conditioning electrical stimulation may be different at various frequencies of stimulation.

Afferent Pathways↗
PubMed2002

Intensity of electric and magnetic fields from power lines within the business district of 60 Ontario communities.

Electric and magnetic fields were measured during the summer of 1998 in south-central Ontario within the business district of 60 communities, ranging in size from 1000 to 2.3 million people. The mean magnetic flux density for the 60 communities was 5.8 mG. Communities with larger populations generally had higher magnetic flux densities than those with smaller populations. Communities with populations above 100,000, between 50,000 and 100,000, between 10,000 and 50,000, and less than 10,000 had mean magnetic flux densities of 14, 7, 4 and 2.4 mG, respectively. The city of Kingston, population 123,000, had the highest mean magnetic flux density (47 mG) while Burks Falls, population 1000, had the lowest (0.8 mG). More than 90% of the sites measured in Kingston, Toronto, Oshawa, London, Pickering Village and Bellville were above 2 mG, the lower limit associated with childhood cancers. In only one community (Burks Falls) were all of the measurements in the business district below 2 mG. Diurnal variations were detected in the magnetic field (but not in the electric field) with highest fields measured during business hours. For electric fields, the mean for the 60 communities was 3.2 V/m. Electric fields were generally low. Eight communities had maximum field strengths above 30 V/m and all of these were associated with overhead wires. In larger communities with underground distribution lines the electric fields were low or undetectable (<0.1 V/m) but the magnetic fields were often high. High electric fields were generally associated with low magnetic fields but the relationship was not sufficiently robust to enable prediction of one from the other. Data for the business district measured during business hours appear to be relatively consistent for both electric field and magnetic flux density over a two-year period. Two classification schemes that can be used independently or in combination are proposed to facilitate community comparisons. One is based on the average intensity of the fields (FI) and the other on the percentage of measurements that exceed a critical limit (CL) that has biological significance. The critical value of 5 V/m is proposed for electric fields and 2 mG for magnetic fields. Both classification schemes use the traffic light analogy for exposure (green-low, amber-medium, red-high exposure) with an additional category (black) for very high exposure. This classification system facilitates information transfer and can easily be understood and used by the public, public utilities, policy makers, and those wanting to practice prudent avoidance.

Cities↗
PubMed2003

Effectiveness and costs of chemical versus electrical cardioversion of atrial fibrillation.

BACKGROUND: Atrial fibrillation is the most common sustained cardiac arrhythmia and has an important impact on costs of medical assistance. Traditional interventions to convert atrial fibrillation to sinus rhythm are antiarrhythmic drugs and external electrical cardioversion. However, the best option for starting the cardioversion is not well established. METHODS: In a multicentre randomised trial of 139 patients with persistent atrial fibrillation lasting less than 6 months, we compared the effectiveness and the cost-effectiveness ratio of initial treatment with chemical or electrical cardioversion. Subjects who did not achieve sinus rhythm with chemical cardioversion were considered to undergo electrical cardioversion and vice-versa. RESULTS: The efficacy of the initial attempt for cardioversion was similar with chemical or electrical cardioversion (74 vs. 73%, P=0.95). However, the strategy of starting with antiarrhythmic drugs was more effective than with electrical procedure (96 vs. 84%, P=0.0016). Initiating with chemical cardioversion was also less expensive than with electrical cardioversion (1240 US dollars vs. 1917 US dollars ; P=0.002). Life-threatening complications occurred only during chemical cardioversion (5%), all of them in patients with structural heart disease. CONCLUSIONS: In patients with persistent atrial fibrillation of less than 6 months, initial chemical or electrical cardioversion appear to be similar but the strategy of starting the cardioversion with antiarrhythmic drugs is more effective and less expensive than starting with the electrical procedure. Patients with structural heart disease undergoing chemical cardioversion seem to be more susceptible to severe complications.

Adult↗
PubMed2001

Characterization of electrically evoked [3H]-D-aspartate release from hippocampal slices.

Electrical stimulation has certain advantages over chemical stimulation methods for the study of neurotransmitter release in brain slices. However, measuring detectable quantities of electrically evoked release of endogenous or radiolabeled markers of excitatory amino acid neurotransmitters has required current intensities or frequencies much higher than those usually required to study other transmitter systems. We demonstrate here that [3H]-D-aspartate (D-ASP) release can be detected from hippocampal slices at lower stimulation intensities in the presence of a glutamate reuptake inhibitor. Subsequently, we optimized the electrical stimulus parameters for characterizing electrically evoked D-ASP release. Under the experimental conditions described, greater than 90% of electrically evoked D-ASP release is calcium-dependent. Evoked D-ASP release is markedly reduced by pre-treating slices with the synaptic vesicle toxin bafilomycin A1 (BAF A1) or in the presence of 10-mM magnesium. Evoked D-ASP release is also reduced to variable degrees by N- and P/Q type voltage-sensitive calcium channel antagonists. Neither spontaneous efflux nor evoked D-ASP release were affected by NMDA, AMPA or group I metabotropic glutamate receptor (mGluR) antagonists. Evoked D-ASP release was reduced in the presence of an adenosine A1 receptor agonist and potentiated by treatment with a group I mGluR5 agonist. Evoked [3H]-D-ASP release was similar in magnitude to evoked [3H]-L-glutamate (L-GLU) release. Finally, in separate experiments using the same electrical stimulus parameters, more than 90% of electrically evoked endogenous L-GLU release was calcium dependent, a pattern similar to that observed for evoked [3H]-D-ASP release. Taken together, these results indicate that electrically evoked [3H]-D-ASP release mimics evoked glutamate release in brain slices under the experimental conditions employed in these studies.

Animals↗
PubMed1997

Subretinal electrical stimulation of the rabbit retina.

A number of disorders results in photoreceptor degeneration, yet spare the inner retinal layers. We are investigating the possibility that retinal function may be restored in such a situation by electric current applied from the subretinal space. In the present study, bipolar strip electrodes receiving electric current from external photodiodes were implanted into the subretinal space of adult rabbits. Recordings were made from the scalp overlying the visual cortex in response to photic flash stimulation of one eye before surgery. This was compared to the visual cortex response caused by subretinal electrical stimulation of the same eye from an implanted strip electrode. Electric current to the strip electrode was provided by an externally connected photodiode that was stimulated at a remote location with a photoflash. The electrical stimulus was recordable as a brief electrical implant spike during stimulation. In addition, after the implant spike, cortical responses were obtained in response to subretinal electrical stimulation that resembled closely the normal light induced visual evoked potential produced by the pre-implanted eye. These results indicate that the visual system can be activated by electrical stimulation from the subretinal space and indicate that this approach may provide a means to restore vision to eyes blinded by outer retinal disease.

Animals↗
PubMed2000

Enhancing effect of electric stimulation on cytotoxicity of anticancer agents against rat and human glioma cells.

Electropermeabilization, or electroporation, has been used to deliver genes or drugs into the cytoplasm through micropores in the cell membrane caused by electric stimulation. The cytotoxic effect of a combination of anticancer agents with electric stimulation on rat C6 and human T98G glioma cells was examined in vitro. Electric pulses of 100 microsec square waves (eight cycles at 1 Hz) at various electric fields were delivered to C6 or T98G glioma cell suspensions in combination with several anticancer agents. Cell growth was evaluated 48-72 h after treatment. Measurement of cell lysis by electric stimulation was used to assess the optimum field strength for electroporation. Electric stimulation enhanced significantly the cytotoxicity of bleomycin to both C6 and T98G cells by more than 1000-fold using an electric field of 1750 V/cm for C6 cells and 1000 V/cm for T98G cells. The enhancement disappeared when bleomycin concentration was reduced to 100 pg/ml. The cytotoxicity of carboplatin was weakly but significantly enhanced by electric stimulation when a high dose of carboplatin was used. However, there was no enhancement of the cytotoxicity of nimustine hydrochloride (ACNU), etoposide, and vincristine. These results indicate that the combination of bleomycin and electroporation is the most potent candidate for electrochemotherapy in vivo.

Animals↗
PubMed2003

Auditory response to intracochlear electric stimuli following furosemide treatment.

The influence of functional hair cells on electrical stimulation of the auditory nerve is an important issue as individuals with significant residual hearing are now cochlear implant candidates. Previous work has shown that chemical deafening during the course of acute experiments changes the auditory nerve's responses to electrical stimulation [Third Quarterly Progress Report, NIH contract N01-DC-9-2106 (2000), Final Report, NIH Contract N01-DC-9-2106 (2002)]. This study extended that work by investigating the changes and subsequent recovery following furosemide injections which reversibly impair hair-cell function [Hear. Res. (1980) 79-89; Hear. Res. 14 (1984) 305-314, J. Physiol. 347 (1984) 685-696; Hear. Res. 71 (1993) 202-207]. Acoustic sensitivity of guinea pig subjects was repeatedly monitored with the click-evoked compound action potential. Responses to single biphasic electric pulses and biphasic electric pulse trains delivered by a monopolar intracochlear electrode were also repeatedly assessed using the electrically evoked compound action potential (ECAP). Our measures demonstrated a clear relationship between the state of hair-cell function and ECAP responses, as changes in the latter coincided with the loss or recovery of acoustic sensitivity. ECAP growth functions demonstrated increased slope and increased maximum (saturation) amplitude. Both trends were reversible and followed approximately the time course of post-furosemide hearing recovery. Additional changes were observed using electric pulse-train stimulation: (1) the magnitude of ECAP amplitude alternation (observed in response to successive stimulus pulses) increased, (2) the degree of ECAP adaptation (measured 80-100 ms after pulse-train onset) increased, and (3) the degree of refractoriness (measured by the ratio of ECAP amplitudes to the second and first pulses) tended to increase. All these trends are consistent with the hypothesis that functional hair cells desynchronize the population of auditory nerve fibers, thereby changing the electrically evoked responses. Viable hair cells may therefore provide positive effects on auditory response to electric stimuli delivered to implant patients with residual hearing, as they may enhance the random activity of the stimulated nerve.

Animals↗
PubMed1997

Chronic electrical stimulation of the auditory nerve at high stimulus rates: a physiological and histopathological study.

A major factor associated with recent improvements in the clinical performance of cochlear implant patients has been the development of speech-processing strategies based on high stimulation rates. While these processing strategies show clear clinical advantage, we know little of their long-term safety implications. The present study was designed to evaluate the physiological and histopathological effects of long-term intracochlear electrical stimulation using these high rates. Thirteen normal-hearing adult cats were bilaterally implanted with scala tympani electrode arrays and unilaterally stimulated for periods of up to 2100 h using either two pairs of bipolar or three monopolar stimulating electrodes. Stimuli consisted of short duration (25-50 microseconds/phase) charge-balanced biphasic current pulses presented at 1000 pulses per second (pps) per channel for monopolar stimulation, and 2000 pps/channel for bipolar stimulation. The electrodes were shorted between current pulses to minimize any residual direct current, and the pulse trains were presented using a 50% duty cycle (500 ms on; 500 ms off) in order to simulate speech. Both acoustic (ABR) and electrical (EABR) auditory brainstem responses were recorded periodically during the chronic stimulation program. All cochleas showed an increase in the click-evoked ABR threshold following implant surgery; however, recovery to near-normal levels occurred in approximately half of the stimulated cochleas 1 month post-operatively. The use of frequency-specific stimuli indicated that the most extensive hearing loss generally occurred in the high-frequency basal region of the cochlea (12 and 24 kHz) adjacent to the stimulating electrode. However, thresholds at lower frequencies (2, 4 and 8 kHz), appeared at near-normal levels despite long-term electrode implantation and electrical stimulation. Our longitudinal EABR results showed a statistically significant increase in threshold in nearly 40% of the chronically stimulated electrodes evaluated; however, the gradient of the EABR input/output (I/O) function (evoked potential response amplitude versus stimulus current) generally remained quite stable throughout the chronic stimulation period. Histopathological examination of the cochleas showed no statistically significant difference in ganglion cell densities between cochleas using monopolar and bipolar electrode configurations (P = 0.67), and no evidence of cochlear damage caused by high-rate electrical stimulation when compared with control cochleas. Indeed, there was no statistically significant relationship between spiral ganglion cell density and electrical stimulation (P = 0.459), or between the extent of loss of inner (IHC, P = 0.86) or outer (OHC, P = 0.30) hair cells and electrical stimulation. Spiral ganglion cell loss was, however, influenced by the degree of inflammation (P = 0.016) and electrode insertion trauma. These histopathological findings were consistent with the physiological data. Finally, electrode impedance, measured at completion of the chronic stimulation program, showed close correlation with the degree of tissue response adjacent to the electrode array. These results indicated that chronic intracochlear electrical stimulation, using carefully controlled charge-balanced biphasic current pulses at stimulus rates of up to 2000 pps/channel, does not appear to adversely affect residual auditory nerve elements or the cochlea in general. This study provides an important basis for the safe application of improved speech-processing strategies based on high-rate electrical stimulation.

Action Potentials↗
PubMed1999

Transdermal water mobility in the presence of electrical fields using MR microscopy.

Magnetic resonance microscopy of skin from hairless rats under the influence of electrical fields was conducted for two cases: 1) low voltage constant electrical fields and 2) high-voltage short pulse, electrical fields. Under conditions of the low voltage and low current iontophoresis, i.e., 0 to 20 V, and 0 to 0.5 mA/cm2, it was found that the skin structure, as observed by magnetic resonance microscopy, did not significantly change until 20 Volts were applied across the 0.1 cm thick skin. Under these conditions, the viable epidermis appeared to swell, and this result corresponded to observations from scanning electron microscopy and other research from the literature. High voltage electrical fields, i.e., 220 V 1 ms pulses repeated once per second, appeared to hydrate the stratum corneum as is consistent with published literature on electroporation. In the case of iontophoresis, water self-diffusion coefficients in the epidermis and hair follicle regions at all voltages were affected by the electrical field. Statistical analysis at the 95% confidence level for the comparison of the average differences between diffusion coefficients with the electrical field on and with the electrical field off for pair matched pixels for the viable epidermis show that for 5 V (p = 0.00377), 10 V (p = 0.0108), 20 V (p = 0.0219) regimes there are statistically significant (p < or = 0.05) changes due to the applied electric field. The same analysis for the hair follicle region at 5 V (p = 6.89 x 10(-7)), 10 V (p = 1.42 x 10(-5)), 20 V (p = 3.23 x 10(-3)) also show statistically significant changes (p < or = 0.05). When the electroporation pulse was applied, the water diffusion coefficients increased by about 30% to 6.6 x 10(-6) cm2/s +/- 2.4 x 10(-7) cm2/s and 8.3 x 10(-6) cm2/s +/- 3.7 x 10(-7) cm2/s, for the epidermis and hair follicle regions, respectively. Significant differences were noted between diffusion coefficients in the viable epidermis and the hair follicles for all cases.

Animals↗
PubMed1999

Tumour blood flow changes induced by application of electric pulses.

The effect of electric pulses on tumour blood flow was investigated in the murine fibrosarcoma SA-1. After the application of short intense electric pulses, relative tumour perfusion was measured using an 86RbC1 extraction technique. A significant reduction of tumour perfusion (approximately 30% of control) was observed within 1 h following the application of eight electric pulses to the tumour. Thereafter, tumour blood flow slowly recovered, almost reaching the pretreatment level by 24 h. No change in perfusion was induced in the untreated contralateral normal leg muscle. A similar pattern of blood flow reduction was induced when a second set of electric pulses was applied to the tumour following a 24 h interval. The degree of tumour blood flow reduction was dependent upon the number of electric pulses applied, at 1040 V, and less effect was observed if less than eight pulses were applied. A modification of the amplitude of the electric pulses resulted in changes in the direction of tumour blood flow response. Tumour blood flow increased following pulses in the range between 80 and 560 V and decreased at amplitudes higher than 640 V. These results demonstrate that the local application of electric pulses to solid tumours can modify tumour blood flow. Pulses of increased amplitude resulted in the progressive reduction of tumour blood flow with a corresponding increase in tumour cytotoxicity as measured by growth delay. Tumour blood flow reduction by electric pulses could have potential in exploiting modalities mediated by tumour hypoxia, e.g. activation of bioreductive agents.

Animals↗
PubMed2006

Revealing sparks: John Wesley and the religious utility of electrical healing.

In the eighteenth century, dramatic electrical performances were favourite entertainments for the upper classes, yet the therapeutic uses of electricity also reached the lower strata of society. This change in the social composition of electrical audiences attracted the attention of John Wesley, who became interested in the subject in the late 1740s. The paper analyses Wesley's involvement in the medical applications of electricity by taking into account his theological views and his proselytizing strategies. It sets his advocacy of medical electricity in the context of his philanthropic endeavours aimed at the sick poor, connecting them to his attempts to spread Methodism especially among the lower classes. It is argued that the healing virtues of electricity entailed a revision of the morality of electrical experiment which made electric sparks powerful resources for the popularization of the Methodist way of life, based on discipline, obedience to established authorities and love and fear of God.

Christianity↗
PubMed2001

Electricity as a medium of psychic life: electrotechnological adventures into psychodiagnosis in Weimar Germany.

When electricity became a commodity in 1900, it furnished Germany with new attractions and revolutionized everyday life with all kinds of tools and gadgets; it also opened up a new space for investigating psycho-physical interaction, reviving ideas of a close linkage between psychic life and electricity. The paper traces the emergence of this electro-psychological framework beyond "electroencephalography," the recording of electrical brain waves, to "diagnoscopy," personality profiling by electric phrenology. Diagnoscopy opens a window onto the scientific and public cultures of electricity and psychical processes in Weimar Germany. It garnered enormous attention in the press and was quickly taken up by several institutions for vocational guidance, because it offered a rapid and technological alternative to laborious psychological testing or "subjective" interviewing. Academic psychology and leading figures in brain research reacted with horror; forging counter measures which finally resulted in this technique being denounced as quackery. A few years later, the press celebrated electroencephalography as a mind-reading device, whereas the neuroscientists remained initially skeptical of its significance and the very possibility of an "electroencephalogram" (EEG) before they adapted electroencephalography as a tool for representing various neuro-psychiatric conditions in patterns of recorded signals. The blending of psychophysiology and electrical engineering marks the formation of an electric epistemology in scientific as well as public understanding of the psyche. The transformations of electrodiagnosis from diagnoscopy to the EEG are indicative of a cultural shift in which electricity changed its role from being the power source for experimental apparatuses to becoming a medium of psychic processes.

Electricity↗
PubMed1996

Anionic gels as vehicles for electrically-modulated drug delivery. I. Solvent and drug transport phenomena.

PURPOSE: The purpose of this study was to elucidate the in vitro behavior of anionic gels as formulation matrices for electrically-modulated drug delivery. Agarose and combinations of agarose with other anionic polymers (carbomer 934P; xanthan gum) were selected and tested to evaluate their potential for drug delivery. METHODS: Electrical current was applied by an automatic crossover power supply to minimize the current fluctuation. Hydrocortisone was selected as the model drug in order to minimize electrostatic interference with drug transport. Syneresis and drug migration were evaluated as a function of current application time and the intensity of electrical current. RESULTS: The data show that electrical current strength and gellant content can affect both the syneresis and drug migration. A linear correlation was found between hydrocortisone loss and mass loss via the exudate. Moreover, in agarose-carbomer 934P gel systems, cumulative gel mass loss is a linear function of time at low intensities of electrical current (e.g., 0.5 mA and 1 mA). However, hydrocortisone distribution, after electrical application, is relatively asymmetric in those agarose-carbomer 934P gels (and in agarose-xanthan gum gels) in contrast to gel matrices containing only agarose. CONCLUSIONS: In this study, the use of carbomer 934P in conjunction with agarose enables the formulator to achieve zero-order release with electrical application. Increased anisotropicity of a gel system due to the application of electrical current could alter the effectiveness of a drug delivery system.

Acrylic Resins↗
PubMedDate not supplied

Effects of electrical stimulation on the histological properties of wounds in diabetic mice.

The purpose of this study was to identify mechanisms underlying electrically stimulated wound closure in diabetic mice. Adult male mice (n = 58) with full-thickness excisional wounds were treated five times using negative polarity over the wound site for 15 minutes each over a 16-day period with sham (0 Volts) or 5.0, 10.0, 12.5 Volts. In addition, animals (diabetic (n = 33) and nondiabetic (n = 22)) received treatments of electrical stimulation (12.5 V), or sham treatment (0 V) at wound sites which were then harvested and prepared for histological analysis at 2, 8, and 16 days postwounding. Using computerized image analysis of sections stained with a picro sirus red-fast green staining technique, we found that increasing doses of electrical stimulation reduced collagen/noncollagenous protein ratios measured in the superficial scar of nondiabetic animals, with no effect in diabetic animals. In the deep scar, lower doses of electrical stimulation (5.0 V) produced significantly (p < 0.01) increased collagen deposition in wounds of nondiabetic animals compared with sham controls. Higher doses of electrical stimulation (12.5 V) were required to produce changes in diabetic animals than were observed in nondiabetic animals. These results suggest that electrical stimulation altered collagen deposition in excisional wounds of diabetic and nondiabetic animals. Electrical stimulation had a differential effect on wound healing in diabetic compared with nondiabetic animals. These data speak to the need to study the effects of electrical stimulation on healing in disease-specific models.

Animals↗