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Field recordings of electric organ discharges and catches of Marcusenius cyprinoides showed that these electric fish form groups and move about in schools. The role electric organ discharges in group cohesion was investigated by comparing interactions in groups of intact and operated, electrically silent fish. The absence of electric organ dischares reduced locomotor activity and resulted in the disappearance of two behaviors: parallel lineup and single file swimming. Electric signals are considered part of a schooling mechanism that aids the fish in maintaining group cohesion in their turbid enviornment and during migration at night.
Electrical sizing of liver cell nuclei gives similar results as histological techniques for the mean volume, the volume distribution and the proportions of the different nuclear volume populations. The electrical method has, compared to histological technics, however, the advantage of higher rapidity and accuracy. Due to the good volume resolution of the improved electrical sizing method two populations of nuclei with different mean volumes can be distinguished in rat liver tissue besides di-, tetra- and octoploid cell nuclei. In addition to the volume distribution curves, the mean electrical resistance of isolated liver nuclei can be determined by the electrical sizing method. A newly developed micromehod provides enough cell nuclei for electrical sizing from only 10 mg liver tissue in a few minutes. This should enable the measurement of nuclear volume distribution curves of human biopsy material from the liver and gastrointestinal tract for diagnostic purposes on a larger scale.
In several species of electric fish with a sex difference in their pulse-type electric organ discharge (EOD), the action potential-generating cells of the electric organ (electrocytes) of males are larger and more invaginated compared to females. Androgen treatment of females and juveniles produces a longer-duration EOD pulse that mimics the mature male EOD, with a concurrent increase in electrocyte size and/or membrane infolding. In Sternopygus macrurus, which generates a wave-type EOD, androgen also increases EOD pulse duration. To investigate possible morphological correlates of hormone-dependent changes in EOD in Sternopygus, we examined electric organs from both fish collected in the field, and untreated and androgen-treated specimens in the laboratory. The electrocytes are cigar shaped, with prominent papillae on the posterior, innervated end. Electrocytes of field-caught specimens were significantly larger in all parameters than were electrocytes of specimens maintained in the laboratory. EOD pulse duration and frequency were highly correlated, and were significantly different between the sexes in sexually mature fish. Nevertheless, no sex difference in electrocyte morphology was observed, nor did any parameters of electrocyte morphology correlate with EOD pulse duration or frequency. Further, whereas androgen treatment significantly lowered EOD frequency and broadened EOD pulse duration, there was no difference in electrocyte morphology between hormone-treated and control groups. Thus, in contrast to results from studies on both mormyrid and gymnotiform pulse fish, electrocyte morphology is not correlated with EOD waveform characteristics in the gymnotiform wave-type fish Sternopygus. The data, therefore, suggest that sex differences in EOD are dependent on changes in active electrical properties of electrocyte membranes.
The fresh water fish Gymnotus carapó produces a continuous series of weak pulsed electric fields in its surroundings and senses disturbances of this field as part of its sensory system. The electric and magnetic properties of the electric organ of this fish were studied. Magnetic fields close to the fish on the order of nT are produced by currents on the order of 10(-4) A in the electric organ of the fish. The electromotive force, the internal resistance, the current, and the electric power of the equivalent circuit were determined noninvasively.
The relationship was examined between the tumoricidal effect and the electrical variables of in vivo electrical impulse chemotherapy. Donryu rats subcutaneously inoculated with AH-109AY hepatocellular carcinomas were given a single high-voltage electrical impulse of varying voltage and duration, 30 min after an intramuscular injection of 4 mg/kg bleomycin. As the voltage (V) was increased from 0 to 5 kV, the tumoricidal effect (E) increased in proportion to the square of the voltage. As the pulse duration (D) was increased from 2.5 to 5.8 ms, the tumoricidal effect increased in direct proportion to it. Combining these results yielded the formula, E = gamma V2D, which indicates that tumoricidal efficacy was proportional to the applied electrical energy. When the electrical energy was kept constant while varying the voltage and duration of pulse, the anticancer effect was the same, confirming this relationship for lower energy levels.
1. Photic stimulation of the mature eye of Strombus can evoke in the optic nerve 'on' activity in numerous small afferent fibres and repetitive 'off' bursts of afferent impulses in a smaller number of larger fibres. 2. Synchronous invasion of the eye by electrically evoked impulses in small optic nerve fibres (apparently the 'on' afferents, antidromically activated) can evoke a burst of impulses in the larger 'off' fibres which propagate away from the eye. Invasion of the eye via one branch of optic nerve can evoke an answering burst in another branch. 3. Such electrically evoked bursts are similar to light-evoked 'off' bursts with respect to their impulse composition, their ability to be inhibited by illumination of the eye, and their susceptibility to MgCl2 anaesthesia. 4. Invasion of the eye by a train of repetitive electrically evoked impulses in the absence of photic stimulation can give rise to repetitive 'off' bursts as well as concomitant oscillatory potentials in the eye which are similar to those normally evoked by cessation of a photic stimulus. 5. The electrically evoked 'off' bursts appear to be caused by an excitatory rebound following the cessation of inhibitory synaptic input from photoreceptors which can be antidromically activated by electrical stimulation of the optic nerve. 6. The experimental results suggest that the rhythmic discharge of the 'off' fibres evoked by the cessation of a photic stimulus is mediated by the abrupt decrease of inhibitory synaptic input from the receptors.
Tumor cells can be killed by heating to 42.5degreesC. It is convenient to localize heating by passing electric current at 500 kHz through tissue between a pair of electrodes. It is desirable to determine, for a given electrode-tissue configuration, what the resulting field and, therefore, current distribution will be. A computer program FFEARS was used to calculate electric field and potential distributions in two dimensions for three simple cases.
Electric parameters, osmolality, temperature, and pH of the suspending medium and the growth phase of cells, etc., are known to influence the efficiency of the pulsed electric field (PEF)-induced DNA transfection of cells. PEF-induced transfection of Escherichia coli JM105 by plasmid DNA PUC18, PUC19, PBR322, and PMSG has been used as a model system to establish quantitative relationships between these parameters and transfection efficiency. The main findings are summarized for experiments using unipolar square wave PEF. (a) For a given field strength (up to 6 kV/cm), the transfection efficiency (TE) was linearly dependent on the pulse width (up to 1 ms). (b) When field strength is fixed, Log [TE] correlated with the number of pulses applied. Similarly, when field duration was fixed, Log [TE] correlated with the number of pulses. (c) In the absence of MgCl2, TE showed a maximal value at 50 mM sucrose and was reduced by several fold at lower and higher sucrose concentrations. Cell survival was nearly constant in the range 1-300 mM sucrose. (d) E. coli in the early and mid-exponential growth phases was more susceptible to PEF for DNA transfection than it was in the stationary phase. (e) For a given set of electric parameters, TE was the highest at neutral pH and was greatly reduced at acidic and alkaline pH. (f) Increasing the temperature from 0 to 37 degrees C resulted in the reduction of TE by three orders of magnitude. This could reflect a rapid shrinking of pores at higher temperatures. (g) TE was inversely proportional to the square of the size of the plasmid DNA. By adjusting the above parameters to optimize transfection, a TE of 1010 1microg-1 DNA (PUC18) has been recorded. Further improvement in percent cell transfection may be expected by a more exhaustive search of conditions than the present study has done.
The present research has originated from observing a 25-year-old man who - after an electrotrauma-- showed a hydrocephalus internus in the pneumoencephalogram. The review of the literature available at that time resulted in obtaining only one information concerning this nexus of related problems; thus the search of patients suffering from this trauma began, but as well experiments on animals. Most of the cats being injured by A.C. actually showed a dilatation of the lateral ventricles. Further experiments on dogs have shown that not only in case of transcerebral but also of peripheral injuries by electric currents of certain strength, distinct states of paling on the brain surface could be observed occurring in consequences of the extreme vasosoconstriction of the meningeal vessels. By a further series of experiments on dogs, there was finally demonstrated that also after peripheral electric irritations resp. injuries of different variations, electric tensions in the brain can be measured by intracerebrally installed electrodes at varying irritatnt voltages; up to now, this possibility has been in contest. Neuropathological investigations showed intracerebral and subarachnoid haemorrhages of different size in all injured animals.
The small intestinal electrical control activity (ECA) was driven by an electrical stimulus and the resultant effects on the frequency and the phase relationships of control waves recorded. The small intestinal ECA can be driven from all sites from which it could be recorded. The mean maximum driven frequency (MDF) was the highest near the pylorus and it decreased distally, but at any given site it was the same before and after dividing the small intestine into small segments. The length of the frequency plateau decreased and phase lag per cm increased with an increase in plateau frequency. The direction of phase lag was orad proximal to a stimulation site and aborad distal to it. Intravenous atropine (up to 100 mug per kg) or reserpinization of dogs before an experiment had no effect on the MDF in the frequency plateau region. The study confirms the validity of an array of bidirectionally coupled relaxation oscillators as a model of small intestinal ECA and shows that the frequency and the phase relationship of small intestinal control waves can be altered by electrical stimulation. The study also points out some differences between the small intestinal and gastric ECA's at the cellular level.
Intracellular electrical and mechanical activities were simultaneously recorded from the longitudinal muscle of isolated guinea-pig jejunum when the preparation was stimulated transmurally by square pulses of 1 msec, 10 Hz, 10-40 V. Transmural stimulation of more than 30 V induced co-ordinated peristaltic waves under intraluminal pressure at levels subthreshold for the peristaltic reflex. Transmural stimulation of less than 30 V induced various types of mechanical responses. After termination of stimulation, rebound excitation was observed. Electrical activities of the longitudinal muscle were compared with various mechanical responses. Slow depolarization without spike potential was recorded when the longitudinal muscle contracted without circular muscle contraction. However, spike potential was recorded from the longitudinal muscle when circular muscle contraction was present as a response. Hyperpolarization was observed soon after the beginning of stimulation. This hyperpolarization was persistent to atropine at 10(-6) g/ml. These electrical and mechanical responses to transmural stimulation disappeared when the preparation was treated with tetrodotoxin at 2 X 10(-7) g/ml.
In cats, the effect of low-frequency electric stimulation of the caudate nucleus on electric activity of neo- and archipaleocortex and on wakefulness-sleep cycle, was studied. The data obtained suggest: 1) at threshold and suprathreshold single electric shocks applied to the caudate nucleus they evoked potential occurs more readily in the sensorimotor area of the neocortex than in the dorsal hippocampus. At 2-6/sec stimulation the evoked potentials in the hippocampus are facilitated and become very stable, whereas in the sensorimotor cortex the most obvious responses occur at the 6-8/sec frequency. However, the evoked potentials are variable in the sensorimotor cortex, and at prolonged 8-12/sec stimulation spindle activity soon develops; 2) behavioral correlate of the synchronized activity in the neo- and archipaleocortical structures during low-frequency stimulation of the caudate nucleus, may involve development of drowsiness with the cessation of stimulation, however, both the EEG and behavioral signs of the drowsiness disappear. The onset of drowsiness following withdrawal of the caudate stimulation, is a rare phenomenon only occurring because of an occasional coincidence of the stimulation with the spontaneous onset of natural sleep; 3) low-frequency caudate stimulation entailing the ECoG synchronization does not cause the transition of paradoxical phase into the slow-wave phase of sleep, and as soon as the stimulation ceases its normal structure recovers. However, if the stimulation of the caudate nucleus is repeated several times in one paradoxical phase, this would shorten the subsequent slow-wave phase and accelerate the onset of the next paradoxical phase; 4) prolonged low-frequency stimulation of the caudate nucleus causing the ECoG synchronization results in a considerable change of wakefulness-sleep cycle in the post-stimulation period: a decrease in the total time of slow-wave sleep due to shortening of its different phases, and an increase in the total amount of paradoxical sleep because of the onset of its phases is rendered more frequent. This effect is more obvious in the first half of the 8-hr cycle.
The purpose of this study was to answer the following questions: (1) Is it more effective to treat spastic cerebral palsy with the Hufschmidt electrical stimulation therapy combined with the Bobath neuro-development treatment or only with the Bobath therapy? (2) Can a general increase in activity be obtained by the electrotherapeutic muscle stimulation? A test group (combined Hufschmidt/Bobath therapy) and a control group (Bobath), both consisting of 10 subjects, were observed for four months. The duration of observation was divided into two four months treatment periods with a rest interval of two months in between. At the start of therapeutic measures, motor activity and psychic condition were tested with corresponding motormetric and psychodiagnostic techniques; three check-up examinations were carried out at the end of the first, and at the beginning and end of the second period of treatment. The motor-metric control examination showed that at the end of the first period the test group had achieved by far the better results, but at the end of the second therapeutic period, both groups were equally successful. The combined electrophysiotherapy hence reached in a relatively shorter time - as it were by leaps and bounds - the optimal obtainable state of functional improvements which, with the Bobath therapy alone, can be effected more slowly but with more continuity. The psychodiagnostic controls clearly indicate that the electrical stimulation produced an unspecified increase in activity, especially after the first phase of treatment, whereas in the second phase this could only be proven in a graded form. The report closes with an examination of the results and their consequences for the implementation of the treatment for cerebral palsied children.
The larval electric organ of Pollimyrus isidori consists of four longitudinal tubes, a dorsal and a ventral pair, which begin behind the skull, end at the beginning of the caudal peduncle and show myotomic segmentation. The elementary units are, apparently, transformed muscle fibres called electrocytes. They are shorter and thicker than muscle fibres, with long stalks and are found in the medial part of the deep lateral muscle. Electron microscopy reveals a clear difference between the anterior and posterior face of the electrocyte. Anteriorly, deep linear invaginations of the surface membrane together with many small vesicles of about 100 nm diameter can be seen. Posteriorly, many plasma membrane invaginations and vacuoles are found together with numerous cytoplasmic organelles--pleiomorphic nuclei, Golgi apparatus, oblong mitochondria and multivesicular bodies. The stalk originates at the posterior face and the nerve terminals are situated at the distal end of the stalk. In the electrocyte, myofibrils, similar to those found in muscle fibres, can be detected with clearly visible Z lines but with only a suggestion of H zones. Two bundles of myofibrils can be seen arranged orthogonally in the electrocyte. Strong acetylcholinesterase activity was found on the anterior face and on the innervated stalk. Under the given recording conditions the overall discharge amplitude of the larval electric organ reaches a maximum of about 100 mV peak to peak. The pulse duration is 1 millisecond and the main phase is head-positive.
Electrical activity, excitation threshold and "steady--state" current-voltage, relationship (estimated under voltage clamp conditions) in the membrane of chicken embryo atrial trabecula were investigated by means of double succrose-gap technique. Application of short (10 msec) electrical stimuli with magnitudes up to 6.10(-5) a (1-150 threshold) resulted in increased excitability and appearance of spontaneous activity. Release of neurotransmitters and polarity of the applied sitmulus are shown not to play a significant role in the changes in membrane excitability observed, the main cause of the latter being the increased sodium permeability of the membrane.
Intravaginal electrical stimulation (IVS) in cats caused urethral closure and bladder inhibition. The aim was to ascertain the electrical parameters most appropriate for these effects. Minimum voltage was used as main criterion to select an effective, non-destructive stimulation when the shape, frequency and duration of the pulses were systematically varied. Urethral closure was achieved at minimum voltage (3 V) with alternating pulses at a frequency of 50 Hz and a pulse duration of 1.5 ms. Corresponding optimal parameters for bladder inhibition were: alternating pulses, 10 Hz and 1.5 ms. Minimum voltage was 1 V. Moreover, the positions of the electrodes were of significance for the responses. The clinical implications of these findings are that: 1)more differentiated treatment of incontinence could be achieved by adapting the stimulation parameters to the cause of incontinence, and 2) specific electrode positions would probably give optimal responses.