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PubMed1976

Coupling in secondary transport. Effect of electrical potentials on the kinetics of ion linked co-transport.

In a previous paper kinetic equations of secondary active transport by cotransport have been derived. In the present paper these equations have been expanded by including the effect of an electrical potential difference in order to make them applicable to the more realistic systems of secondary active transport driven by the gradients of Na+ or H+. Thermodynamically an electrical potential difference is as a driving force fully exchangeable with an equivalent chemical potential difference. This is not necessarily so for the kinetics of co-transport. It is not always the same whether a given difference in electrochemical activity of the driver ion is mainly osmotic, i.e. due to difference in concentration, or electric, i.e. due to a difference in the electrochemical activity coefficient. In most cases a difference in concentration is more effective in driving co-transport than is an equivalent difference in electrical potential leading to the same difference in electrical activity. The effectiveness of the latter highly depends on the model, whether it is of the affinity type or of the velocity type, but also on whether the loaded or the unloaded carrier bears an electrical charge. With the same electrical potential difference co-transport is as a rule faster if the ternary complex rather than the empty carrier is charged. Also the "standard parameters", (see Glossary, page 62) Jmax and Km, of the overall transport respond differently to the introduction of an electrical potential difference, depending on the model. So an electrical potential difference will mostly affect Km if the loaded carrier is ionic, and mostly Jmax if the empty carrier is ionic, provided that the mobility of the loaded carrier is greater than that of the empty one. On the other hand, distinctive criteria between affinity type and velocity type models are partly affected by an electrical potential difference. If the translocation steps of loaded and unloaded carrier are no longer rate limiting for the overall transport, electrical effects on the transport rate are bound to vanish as does the activation by co-transport.

Binding Sites↗
PubMed1985

Involvement of different opioid receptor subtypes in electric shock-induced analgesia and motor suppression in the rat.

We have investigated the correlation of electric shock-induced behavioral changes and functional alterations of endogenous opioid receptor subtypes. The degree of electric shock-induced behavioral changes, such as analgesia and motor suppression, was dependent on the duration of and time after electric shock application. The electric shock-induced behavioral changes were completely antagonized by naloxone. The apparent development of tolerance to both behavioral effects as a result of successive daily electric shock was different: Tolerance to electric shock-induced analgesia developed after 2 days' successive electric shock application, while tolerance to motor suppression was not observed even after 7 days' successive electric shock application. There was a decrease of [3H][D-Ala2, Met5]enkephalinamide ([3H]DAMEA, delta agonist) binding and an increase of [3H]naloxone (mu antagonist) binding when potent electric shock-induced analgesia developed. On the other hand, the binding of [3H]DAMEA and [3H]ethylketocyclazocine (kappa agonist) was significantly changed when locomotion was suppressed. These results suggest strongly that different opioid systems may participate in electric shock-induced analgesia and motor suppression: electric shock-induced analgesia and motor suppression may be mediated by mu/delta and kappa/delta receptors, respectively.

Animals↗
PubMed2001

Feasibility of a left atrial electrical disconnection procedure for atrial fibrillation using transcatheter radiofrequency ablation.

INTRODUCTION: An effective, catheter-based treatment for persistent atrial fibrillation (AF) remains elusive. This study assessed the feasibility of transcatheter left atrial (LA) electrical disconnection and its effect on AF inducibility. METHOD AND RESULTS: Thirteen anesthetized swine underwent noncontact mapping of the right atrium (RA) during coronary sinus (CS) pacing. Sites of earliest RA activation were identified using isopotential maps. An ablation catheter was navigated to these sites and a cluster of radiofrequency (RF) lesions applied until earliest activation shifted to a new site. The procedure was repeated until the atria were electrically disconnected. AF induction was attempted before and after ablation. Earliest RA activation was the CS os during proximal CS pacing and Bachmann's bundle during distal CS pacing. These two sites were successfully ablated in all 13 animals. Earliest activation then shifted to the fossa ovalis. RF energy was applied at a median of 2.5 sites (range 1 to 5) around the fossa, then at sites in the triangle of Koch, septum, cavotricuspid isthmus, and posterior wall. Atrial electrical disconnection was achieved in 10 of 13 animals (5 LA electrical disconnection, 3 RA electrical disconnection, 2 biatrial electrical disconnection with complete heart block). After atrial electrical disconnection, the LA became electrically silent. Before ablation, AF was inducible in every animal. After atrial electrical disconnection, AF was inducible in 3 of 10 animals. CONCLUSION: Atrial electrical disconnection is feasible using noncontact mapping and RF ablation. Successful electrical disconnection of the atria reduces AF inducibility. This approach is worthy of further evaluation as a management strategy for persistent AF, combined with device therapies.

Animals↗
PubMed2005

Mixed electric-magnetic second-order nonlinear optical response of helicenes.

The mixed electric-magnetic second-order nonlinear optical responses of oriented films of helicenes have been computed ab initio using the random phase approximation method and compared to the pure electric-dipole counterpart. It turns out that the mixed electric-magnetic responses can be of the same order of magnitude as the pure electric-dipole counterpart when there is no donor/acceptor (D/A) substituent or these D/A pairs are weak, i.e., when the pure electric-dipole response is small. When adding strong D/A substituents, the pure electric-dipole response increases substantially and much more than its mixed electric-magnetic counterpart. Consequently, the ratio between the mixed electric-magnetic and pure electric responses decreases. Although there is no general rule, the mixed responses evolve as a function of substitution quasi similarly to the pure electric contribution. This study confirms therefore the possibility of tuning the mixed electric-magnetic response by employing appropriate chiral molecules.

Journal Article↗
PubMed2005

Electrical feedback in the cone pedicle: a computational analysis.

One of the fundamental principles of neuroscience is that direct electrical interactions between neurons are not possible without specialized electrical contacts, gap junctions, because the transmembrane resistance of neurons is typically much higher than the resistance of the adjacent extracellular space. However it has been proposed that in the retina direct electrical interactions between cones and second-order neurons occur due to the specific morphology of the cone synaptic terminal. This electrical mechanism could potentially explain the phenomenon of "negative feedback" from horizontal cells to cones and the recent finding that the tips of horizontal cell dendrites contain hemichannels has rekindled interest in the idea. We quantitatively evaluated the possibility that hemichannels and/or glutamate channels mediate electrical feedback from horizontal cells to cones. The calculations show that it is unlikely that an electrical mechanism plays a significant functional role because 1) the necessity of preserving adequate cone-to-horizontal-cell synaptic transmission limits the extracellular space resistance and the horizontal-cell dendritic transmembrane resistances to values at which the effectiveness of electrical feedback is very low and its electrical effect on the cone presynaptic membrane is negligible, 2) electrical feedback is most effective in the dark and weaker during light adaptation, which contradicts the experimental data, and 3) electrical negative feedback is associated with much stronger electrical positive feedback from horizontal cells to cones, a phenomenon that has never been reported. Therefore it is likely that negative feedback from horizontal cells to cones is chemical in nature.

Animals↗
PubMed2005

Theoretical analysis of pre-receptor image conditioning in weakly electric fish.

Electroreceptive fish detect nearby objects by processing the information contained in the pattern of electric currents through the skin. The distribution of local transepidermal voltage or current density on the sensory surface of the fish's skin is the electric image of the surrounding environment. This article reports a model study of the quantitative effect of the conductance of the internal tissues and the skin on electric image generation in Gnathonemus petersii (Günther 1862). Using realistic modelling, we calculated the electric image of a metal object on a simulated fish having different combinations of internal tissues and skin conductances. An object perturbs an electric field as if it were a distribution of electric sources. The equivalent distribution of electric sources is referred to as an object's imprimence. The high conductivity of the fish body lowers the load resistance of a given object's imprimence, increasing the electric image. It also funnels the current generated by the electric organ in such a way that the field and the imprimence of objects in the vicinity of the rostral electric fovea are enhanced. Regarding skin conductance, our results show that the actual value is in the optimal range for transcutaneous voltage modulation by nearby objects. This result suggests that "voltage" is the answer to the long-standing question as to whether current or voltage is the effective stimulus for electroreceptors. Our analysis shows that the fish body should be conceived as an object that interacts with nearby objects, conditioning the electric image. The concept of imprimence can be extended to other sensory systems, facilitating the identification of features common to different perceptual systems.

Journal Article↗
PubMed1989

Balloon electric shock ablation. Effects on ventricular structure, function, and electrophysiology.

We have recently developed a transatrial balloon approach for intraoperative endocardial mapping of ventricular tachycardia, which can be performed in the intact ventricle. In selected patients, we have eliminated the arrhythmia by passing a series of electric currents through specific beads on the balloon array. The goal of this new technique, balloon electric shock ablation, is to create a homogenous scar in the subendocardial target area identified by mapping. Experimental data exist on the effects of catheter delivery of electric discharges to the myocardium, but no data are available on the effects of balloon electric shock ablation. We have performed balloon electric shock ablation in animals (nine cathodal shocks of 100 J given through a 4 cm2 electrode grid). Ventricular function was assessed at 6 weeks and compared with function after a simple ventriculotomy and with function in control animals having no operation. Gated nuclear ventriculograms were obtained during volume loading. Myocardial performance and diastolic pressure volume relationships were determined for the three groups. After balloon electric shock ablation or ventriculotomy, left atrial pressures were increased at similar end-diastolic volumes, which indicated decreased ventricular compliance. The trend reached statistical significance (compared with data from control animals) only in the group undergoing balloon electric shock ablation. Myocardial performance (stroke work index/end-diastolic volume relationship) was unchanged in the three groups. In the long-term balloon electric shock ablation preparation, an electrophysiologic study (including burst pacing) failed to induce ventricular arrhythmias. At 6 weeks, the lesion created by balloon electric shock ablation was a layer of homogenous mature scar with sharply defined borders. There was no evidence of additional injury to the surrounding myocardium or to the mitral valve apparatus. These studies show that delivery of a series of electric shocks through a 1 cm balloon grid of electrodes can create an area of homogeneous, electrically inert scar and that this procedure when performed in healthy dog hearts has no significant effect on the structure and function of the rest of the left ventricle.

Animals↗
PubMed1996

Electric myocardial impedance registration in humoral rejection after heart transplantation.

BACKGROUND: Because of the absent lymphocyte infiltrate, humoral-mediated rejection after heart transplantation is not diagnosed by the usual staining technique (hematoxylin-eosin method) of the endomyocardial biopsy specimen. However, humoral rejection is characterized by a distinct myocardial edema caused by capillary leakage. Because tissue edema increases the electric myocardial impedance of the corresponding tissue compartment the electric myocardial impedance method should be able to detect these episodes more reliably than biopsy. METHODS: To evaluate this hypothesis eight DLA-matched beagle dogs were subjected to heterotopic neck heart transplantation after multiple sensitization by skin grafts of the heart donor. For electric myocardial impedance registrations rectangular impulses (wide 1 msec) were applied over two intramyocardial electrodes and the impulse response was registered. Day-to-day comparisons were made and an increase of electric myocardial impedance of 10% or more was used as an indicator of rejection. To assess the influence of edema caused by electrode implantation, cortisone administration, narcosis, ischemia, or reperfusion on the electric myocardial impedance, identical electrodes were implanted in the native hearts of five additional dogs via lateral thoracotomy. These animals each received 100 mg methylprednisolone between postoperative days 20 and 22 and underwent heterotopic neck heart transplantation on postoperative day 28 without previous sensitization (protocol 2). Electric myocardial impedance electrodes were also implanted in these allografts (protocol 3). After transplantation myocardial biopsies were done every 2 days and the samples graded according to the International Society for Heart and Lung Transplantation classification in all dogs. RESULTS: Despite triple-drug immunosuppression (cyclosporine A, prednisolone, azathioprine) humoral rejection developed in all sensitized dogs as established by immunofluorescent staining of myocardial biopsy samples and functional deterioration. All episodes were diagnosed by electric myocardial impedance (sensitivity 100%), whereas only in one case the biopsy specimen was positive (International Society for Heart and Lung Transplantation grade > 1) (sensitivity 12.5%). All eight episodes could be treated successfully, that is, myocardial performance and electric myocardial impedance showed an immediate and full recovery. During the first 12 days none of the nonsensitized dogs exhibited rejection. Protocol 2 indicated that narcosis and the administration of cortisone did not per se have an influence on electric myocardial impedance and the influence of electrode implantation was negligible. Contrarily, edema caused by ischemia and reperfusion during transplantation (protocols 1 and 3) led to a significant increase in electric myocardial impedance. However, after 2 days this edema had faded away such that it no longer disturbed rejection diagnosis. CONCLUSION: We conclude that the registration of the electric myocardial impedance diagnoses humoral rejection episodes after heart transplantation not only reliably but also early, that is, before the onset of irreversible graft damage.

Animals↗
PubMedDate not supplied

Variability and consistency of electric and magnetic field occupational exposure measurements.

There is widespread scientific and public interest in possible health effects from exposure to electric and magnetic fields at frequencies associated with electricity use. Electric and magnetic field exposure assessment presents specific problems, among which are the inherent variability in exposure, the lack of robust statistical summary measures, and the lack of an accepted metric based on biological response. These pose challenges in defining distinct exposure groups, a basic goal for exposure assessments used in epidemiological studies. This paper explores the extent to which distinct electric and magnetic field exposure groups can be defined, by examining the variability and consistency of occupational electric and magnetic field exposure measurements among studies and within individual studies. Principal analyses are made by job titles because they are the most frequently used descriptors for stratifying occupational exposures to electric and magnetic fields. Methodological issues affecting the degree of consistency in measured electric and magnetic field exposures among occupational environments are also examined. Exposures by job title reported from electric and magnetic field measurement studies are summarized by general job category and industry. Analyses are performed both within and between job categories. Distributions of daily measured exposures for job categories taken from three large studies in the U.S. electric utility industry are compared to investigate consistency of exposures at a more detailed level. Analyses of reported personal exposure measurements from many studies and countries are consistent with less rigorous observations made heretofore on the basis of individual studies. In these studies, significantly elevated electric and magnetic field exposures are found in the electrician, lineworker, and substation worker categories; significantly elevated magnetic field exposures are also noted in the generation worker category; and magnetic field exposures in these groups are consistent across countries. Analyses within and among the elevated exposure job categories indicate that there are no significant differences between them. Among the studies, it is not possible to distinguish between exposures for well-defined groups within the categories, such as between transmission lineworkers and distribution lineworkers in the lineworker category; between generation operators and generation mechanics; or between substation operators and substation maintenance workers. This information provides a context for past studies and will help future efforts to define distinct occupational exposure groups exposed to electric and magnetic fields. Compilations of measured personal exposure data by industry and job title have been prepared as appendices (available from the author upon request).

Analysis of Variance↗
PubMed1997

Mechanisms of pediatric electrical injury. New implications for product safety and injury prevention.

OBJECTIVES: To determine age-specific mechanisms of electrical injury in children, to examine product safety regulation of the major sources of electrical injury hazard, and to assess the adequacy of current prevention strategies. DESIGN: Case series of 144 pediatric and adolescent electrical injuries in patients seen in the specialized burn center and tertiary care hospital between 1970 and 1995, examination of Consumer Product Safety Commission product recall reports for electrical injury hazards between 1973 and 1995, and review of the National Electric Code. RESULTS: Eighty-six cases of electrical injuries resulted from low-voltage (< 1000-V) exposures, all occurring within the home. In children aged 12 years and younger, household appliance electrical cords and extension cords caused more than 64 (63%) of 102 injuries, whereas wall outlets were responsible for only 14 (15%) of injuries. Fifty-eight cases resulted from high-voltage exposures, accounting for 38 (90%) of 42 injuries in children older than 12 years. No federal safety regulations for electrical cords exist, although voluntary standards have been adopted by many manufacturers. Among 383 consumer products identified by the Consumer Product Safety Commission to be electrical injury hazards, 119 were appliance cords, extension cords, or holiday stringed light sets. Several products numbered more than 1.5 million units in US household distribution prior to the investigation by the Consumer Product Safety Commission. CONCLUSIONS: Household electrical cords are the major electrocution hazard for children younger than 12 years, yet no federal safety mandates exist. Despite voluntary standards, noncompliant manufacturers can introduce vast numbers of unsafe cords onto the US household market every year. Conversion of existing voluntary safety guidelines into federally legislated standards may be the most effective intervention against pediatric electrocutions.

Accidental Falls↗
PubMed1990

The electric field dependence of DNA mobilities in agarose gels: a reinvestigation.

The electric field dependence of the electrophoretic mobility of linear DNA fragments in agarose gels was reinvestigated in order to correct the observed mobilities for the different temperatures actually present in the gel during electrophoresis in different electric field gradients. When corrected to a common temperature, the electrophoretic mobilities of DNA fragments less than or equal to 1 kilobase pairs (kbp) in size were independent of electric field strength at all field strengths from 0.6 to 4.6 V/cm if the gels contained less than or equal to 1.4% agarose. The mobilities of larger DNA fragments increased approximately linearly with electric field strength. If the agarose concentration was higher than 2%, the mobilities of all DNA fragments increased with increasing electric field strength. The electric field dependence of the mobility was larger in gels cast and run in Tris-borate buffer (TBE) than in gels cast and run in Tris-acetate buffer (TAE), and was more pronounced in gels without ethidium bromide incorporated in the matrix. Ferguson plots were constructed for the various DNA fragments, both with and without extrapolating the temperature-corrected mobilities to zero electric field strength. Linear Ferguson plots were obtained for all fragments less than or equal to 12 kbp in size in agarose gels less than or equal to 1.4% in concentration if the mobilities were first extrapolated to zero electric field strength. Concave upward curvature of the Ferguson plots was observed for DNA fragments greater than or equal to 2 kbp in size at finite electric field strengths. Convex downward curvature of the Ferguson plots was observed for DNA fragments greater than or equal to 1 kbp in size in agarose gels greater than or equal to 2% in concentration. The mobilities of the various DNA fragments, extrapolated to zero agarose concentration and zero electric field strength, decreased with increasing DNA molecular weight; extrapolating to zero molecular weight gave an "intrinsic" DNA mobility of 2.7 x 10(-4) cm2/Vs at 20 degrees C. The pore sizes of LE agarose gels cast and run in TAE and TBE buffers were estimated from the mobility of the DNA fragments.(ABSTRACT TRUNCATED AT 400 WORDS)

Boric Acids↗
PubMed1995

Electrically-evoked release of taurine in the rat vas deferens: evidence for a purinoceptor-mediated effect.

Release of taurine evoked by electrical stimulation (2700 pulses; 5 Hz; 10 mA unless stated otherwise) and its dependence on noradrenaline and ATP was studied in isolated, perifused rat vas deferens. Outflow of noradrenaline was also measured in some experiments. The basal outflow of taurine averaged 3.90 +/- 0.32 nmol/g tissue per min. Electrical stimulation increased the outflow to about 4 times basal values. The electrically-evoked overflow averaged 128.0 +/- 11.7 nmol/g. An increase in current strength to 40 mA increased the evoked overflow by about 50%. At either current strength, the evoked overflow of taurine (and noradrenaline) was abolished by tetrodotoxin. Ca(2+)-deprivation blocked the overflow of taurine elicited by 10 mA and increased the overflow elicited by 40 mA pulses (but abolished noradrenaline overflow under either condition). Neither prazosin nor pretreatment of the rats with reserpine reduced electrically-evoked overflow of taurine (although reserpine pretreatment abolished evoked noradrenaline overflow). Tyramine (100 mumols/l; 9 min) caused an overflow of taurine 36% of that caused by electrical stimulation (but an overflow of noradrenaline 3 times higher than that evoked by electrical stimulation). Exogenous noradrenaline (9 min) caused a concentration-dependent overflow of taurine with a maximal effect at 162 mumol/l, amounting to 33% of the electrically-evoked overflow. alpha,beta-Methylene ATP (19 mumols/l) elicited an overflow of taurine that faded despite continued exposure to the drug and amounted to 62% of the response to electrical stimulation. Thirty minutes after the start of application of alpha,beta-methylene ATP, electrically-evoked overflow of taurine was greatly reduced. Suramin (100 mumols/l) also reduced taurine overflow in response to electrical stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed2006

Inhibitory effects and mechanisms of colonic electric stimulation on gastric and rectal tone in conscious dogs.

PURPOSE: Colonic electric stimulation has been shown to alter motor functions of the colon; however, its effects on other organs of the gut have been investigated rarely. METHODS: This study was performed in 12 dogs implanted with one pair of colonic serosal electrodes and a gastric cannula. Experiments were performed to study: 1) the effect of colonic electric stimulation on proximal gastric tone and compliance; 2) the effect of colonic electric stimulation on rectal tone and compliance; 3) the sympathetic mechanism involved in the effects of colonic electric stimulation on gastric/rectal tone. A computerized barostat was used to assess gastric/rectal tone and compliance. RESULTS: Colonic electric stimulation inhibited both gastric and rectal tone with a higher potency in gastric tone. Colonic electric stimulation reduced gastric but not rectal compliance. The inhibitory effect of colonic electric stimulation on gastric tone but not rectal tone was abolished by an adrenergic blockade, guanethidine. CONCLUSIONS: Colonic electric stimulation inhibits both gastric and rectal tone with a higher potency in inhibiting gastric tone. Colonic electric stimulation reduces gastric but not rectal compliance. The inhibitory effect of colonic electric stimulation on gastric tone seems to be mediated by the sympathetic pathway.

Adrenergic Agents↗
PubMed2005

Electrical inhibition of preterm birth: inhibition of uterine contractility in the rabbit and pup births in the rat.

OBJECTIVE: The purpose of this study was to inhibit uterine contractility during parturition with an electrical current, which is called electrical inhibition, in the rabbit and the rat. STUDY DESIGN: We studied the electrical inhibition of in vitro spontaneously contracting preterm or term gestational rat myometrium tissue and in vivo spontaneously contracting uterus either directly in the rabbit and rat or transvaginally in the rat. Values for myometrial tension, intrauterine pressure, pup birth intervals, and electromyographic activity before and after electrical inhibition were compared. RESULTS: Electrical inhibition decreased rat in vitro myometrial tension by 50%, decreased in vivo rabbit intrauterine pressure by 48%, decreased in vivo rat intrauterine pressure by 80%, and increased birth intervals (latency) by factors of 50 (direct electrical inhibition) and 20 (transvaginal electrical inhibition). All electromyographic activity parameters were reduced significantly. CONCLUSION: Electrical inhibition of the uterus is possible. Electrical inhibition is rapid and localized; the duration can be prolonged, and the reversibility is spontaneous. Electrical inhibition may be a new method of tocolysis in the human.

Animals↗
PubMed2004

Electrical cardioversion of emergency department patients with atrial fibrillation.

STUDY OBJECTIVE: Electrical cardioversion of emergency department (ED) patients with atrial fibrillation has not been well investigated. The objective of this study is to identify the outcomes and complications associated with ED electrical cardioversion of patients with atrial fibrillation. METHODS: This retrospective health records survey investigated a consecutive cohort of ED patients with atrial fibrillation who underwent electrical cardioversion in 4 EDs during a 42-month period. Trained personnel reviewed medical records for demographic characteristics, clinical descriptors, medical interventions, complications, and ED return visits within 7 days. Data were analyzed using descriptive statistics. RESULTS: The study population consisted of 388 patients (mean age 61 years; range 20 to 93 years). Duration of atrial fibrillation was less than 48 hours in 99% of the cohort. Electrical cardioversion was successful in 332 (86%) patients. Twenty-eight complications were noted in 25 electrical cardioversion encounters: 22 attributed to procedural sedation and analgesia and 6 attributed to electrical cardioversion. Three hundred thirty-three (86%) patients were discharged to home from the ED: 301 after electrical cardioversion success and 32 with electrical cardioversion failure. Thirty-nine patients (10%) returned to the ED within 7 days, 25 of these patients (6% of successful electrical cardioversion patients) returned because of relapse of atrial fibrillation. CONCLUSION: In this multicenter cohort, selected ED patients with atrial fibrillation had high rates of electrical cardioversion success, infrequent hospital admission, and few immediate and short-term complications.

Adult↗
PubMed2003

Occupational electrical injuries in the United States, 1992-1998, and recommendations for safety research.

PROBLEM: CFOI and SOII data show that 2,287 U.S. workers died and 32,807 workers sustained days away from work due to electrical shock or electrical burn injuries between 1992 and 1998. METHOD: The narrative, work activity, job title, source of injury, location, and industry for each fatal electrical accident were examined. A primary causal factor was identified for each fatality. RESULTS: Electrical fatalities were categorized into five major groups. Overall, 44% of electrical fatalities occurred in the construction industry. Contact with overhead power lines caused 41% of all electrical fatalities. DISCUSSION: Electrical shock caused 99% of fatal and 62% of nonfatal electrical accidents. Comprising about 7% of the U.S. workforce, construction workers sustain 44% of electrical fatalities. Power line contact by mobile equipment occurs in many industries and should be the subject of focused research. Other problem areas are identified and opportunities for research are proposed. IMPACT ON INDUSTRY: Improvements in electrical safety in one industry often have application in other industries.

Causality↗
PubMedDate not supplied

Preparative concentration and size fractionation of DNA by porous media using a combination of flow and low electric field strength.

The retention of DNA by porous media during chromatography with an applied axial electric field was investigated. DNA was retained by negative electric fields in columns packed with Sephadex G-75 and G-25. A negative field was defined as the electric field orientation in which the direction of electrophoresis was opposing the direction of buffer flow (positive electrode at the column inlet). A positive field was not effective at retaining the DNA. The electric field strength required to retain the DNA was dependent upon the buffer flow rate. The retention of DNA using Sephadex G-25, a gel filtration medium with a higher degree of cross-linking, required higher electric fields than the more porous Sephadex G-75. A dilute DNA solution was concentrated at the inlet of the chromatography bed by an electric field. Mixtures of DNA restriction fragments were used to determine size-dependent retention. DNA was size-fractionated by varying the electric field strength and flow rate. At a given electric field strength and flow rate, the lower molecular weight DNA fragments were not as strongly retained as the higher molecular weight fragments. Decreasing the flow rate or increasing the electric field strength resulted in increased retention of the lower molecular weight DNA fragments. In this manner, by selecting a specific set of conditions (packing material, flow rate, and electric field strength), the molecular weight of DNA fragments retained by the column can be adjusted. Efficient separation of high molecular weight DNA from bovine serum albumin, a protein with high electrophoretic mobility, was demonstrated using a field of 2 V/cm in a column packed with Sephadex G-75.

Animals↗
PubMed1999

Direct and indirect effects of electrical stimulation on the motility of human sperm.

BACKGROUND: Electroejaculation is a technique that is becoming more frequently available for obtaining sperm from men with spinal cord injury or psychogenic anejaculation. However, the effect of electrical stimulation on the movement of human sperm has not been clarified. METHODS: Electrical stimulation was applied to ejaculated semen or washed sperm via a pair of electrodes in the sperm-counting chamber while sperm motility was recorded using a computer-assisted semen analyzer. RESULTS: When monopolar pulse stimulation was applied to sperm, the motility rate and velocity of sperm near both electrodes decreased according to the number of pulses and current despite low electrical voltages. However, motility of sperm in the center between electrodes did not change. When extremely high-voltage electrical stimulation with more than 80 V/2 mm (distance between electrodes) was applied to sperm, sperm stopped moving regardless of their location between the electrodes, despite a low electrical current and low energy. Replicating clinical rectal probe electroejaculation, continuous sinusoidal alternating current at 50 V/10 mm was applied to a untreated ejaculated semen. The motility of sperm, except for those adjacent to both electrodes, did not change after stimulation for 60s, despite a high electrical energy. CONCLUSIONS: The motility of sperm near electrodes was decreased when high electric current flowed, despite low electrical voltages. In addition, sperm lost their motility when extremely high-voltage electrical stimulation was applied. However, electrical stimulation during clinical rectal probe electroejaculation seems to have no effect on sperm motility.

Ejaculation↗