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L Vodovnik

Publications and source records attributed to L Vodovnik.

At least 19 recordsLinked to original sources
PubMed1997

Local changes in membrane potential intensify neutrophil oxidative burst.

The aim of this paper is to study the effects of the pulsed electrical field/current alone or combined with ionomycin, fMLP and PMA, the chemical stimuli that operate through distinctly different activation pathways, on the time course of the oxidative burst response in human neutrophils. Neither the control groups nor the neutrophils treated with electrical field alone showed any increase in oxidative burst activity measured by the luminol-enhanced chemiluminescence technique. It was found that electrical treatment potentiates chemically induced activation with either of the chemical stimulators used. The integrated oxidative burst response--which represents a cumulative amount of oxygen metabolites produced during whole response--was 87% higher in neutrophils treated with a combination of ionomycin and an electric field than in solely ionomycin treated cells, while the peak level of the response was 114% higher. In neutrophils stimulated with fMLP the electrochemical treatment caused a 32% higher integral response as well as a 22% higher peak level compared to the neutrophils treated with chemical stimulant alone. The integrated oxidative burst response in the combined PMA and electric treatment was only 4.7% higher than in the cells treated with PMA alone, and no significant difference in the peak level was found. The results suggest that electric field treatment preferentially stimulates calcium-induced activation with ionomycin rather than calcium-dependent activation with fMLP or PMA.

Adolescent↗
PubMed1995

Effects of transcutaneous electrical nerve stimulation (TENS) on spasticity in patients with hemiplegia.

The effect of afferent cutaneous electrical stimulation on the spasticity of leg muscles was studied in 20 patients with chronic hemiplegia after stroke. Stimulation electrodes were placed over the sural nerve of the affected limb. The standard method of cutaneous stimulation, TENS with impulse frequency of 100 Hz, was applied. The tonus of the leg muscles was measured by means of an electrohydraulic measuring brace. The EMG stretch reflex activity of the tibialis anterior and triceps surae muscles was detected by surface electrodes and recorded simultaneously with the measured biomechanical parameters. In 18 out of 20 patients, a mild but statistically significant decrease in resistive torques at all frequencies of passive ankle movements was recorded following 20 min of TENS application. The decrease in resistive torque was often (but not always) accompanied by a decrease in reflex EMG activity. This effect of TENS persisted up to 45 min after the end of TENS. The results of the study support the hypothesis that TENS applied to the sural nerve may induce short-term post-stimulation inhibitory effects on the abnormally enhanced stretch reflex activity in spasticity of cerebral origin.

Adult↗
PubMed1994

Electric treatment of human melanoma skin lesions with low level direct electric current: an assessment of clinical experience following a preliminary study in five patients.

In this study we have investigated the effects of negative low level direct electric current electrotherapy (current: 1 milliampere; treatment time: 30 minutes) in metastatic or primary melanoma skin lesions. After 12 applications in five patients, tumour regression was observed in all evaluable melanoma skin lesions; four of them were classified as partial responses. This study shows that locally applied electrotherapy with a negative low level direct electric current is an effective treatment that results in reduction of tumour mass of human melanoma skin lesions, and it is possible that it has a positive influence on the course of the metastatically disseminated melanoma. No serious side effects were observed.

Adult↗
PubMed1993

Treatment of chronic wounds by means of electric and electromagnetic fields. Part 2. Value of FES parameters for pressure sore treatment.

Subjects with spinal cord injury are often distressed by pressure sores, which usually appear after prolonged pressure (wheelchair, bed) across the soft tissue which has already lost sensibility and has diminished microcirculation. The healing ability and its dynamics depend on the state of the subject's overall health. Consequently, evaluation of a particular treatment requires careful consideration of as many as possible of the parameters relevant to healing and an adequate criterion for assessing the state of the pressure sore. Bearing in mind these two circumstances, the results of a multicentre clinical study are analysed. The aim of the study was to test two hypotheses: first that healing is faster when sores are also treated by electric currents (ECs) (in addition to conventional treatment); and secondly that there exist differences in the efficiency of the treatment if direct or low-frequency pulsed currents (FES parameters) are applied. The data analysed show that pressure sores are likely to heal twice as fast when treated with low-frequency pulsed currents. EC seems to improve the healing rate in cases where the natural healing mechanisms of the body are not sufficient (chronic wounds, older subjects).

Adult↗
PubMed1992

Pulsed electric current enhances the phorbol ester induced oxidative burst in human neutrophils.

Oxidative burst (OB) response in human neutrophils, measured with chemiluminescence (CL), has been used to determine whether pulsed electric current (PEC) might induce a functional response in these electrically nonexcitable cells, and also whether it might modify cellular response to tumor-promoting phorbol ester (PMA). Five minutes of PEC treatment caused no significant changes in neutrophil CL levels in HBSS (1.2 mM Ca2+ concentration) as well as in HBSS-EGTA, where the extracellular Ca2+ concentration was reduced to less than 30 nM. The CL level of PMA-activated neutrophils in HBSS was 52% higher than in HBSS-EGTA. In HBSS the CL level, after the combined PMA and PEC treatment, was 53% higher than in PMA-alone-treated neutrophils. Activation of the OB in HBSS-EGTA with PMA and PEC was 13% higher than in solely PMA treated neutrophils. The results suggest that in neutrophil OB response, the PEC effect is closely related with cellular calcium mobilization, since depletion of extracellular Ca2+ decreased the PEC effect.

Adult↗
PubMed1992

Modified cell proliferation due to electrical currents.

In view of the evidence that electrical currents may enhance healing of chronic wounds and retard tumour growth it is suggested that these currents normalise cell proliferation. Additional support to this contention is given by two reports: one on healing of pressure sores in man and one on tumour growth retardation in mice. The effect of an ionic environment on the cell cycle is analysed. Finally a hypothesis attempting to explain the normalising effect of electrical currents on cell proliferation is proposed. It is known that non-dividing cells, e.g. mature neurons, have high transmembrane potential (TMP) whereas fast-dividing cells, e.g. cancerous cells, have low TMP. When a cell is exposed to an electrical field, one side of the cell becomes hyperpolarised while the opposite side is depolarised. Assuming a nonlinear relationship between TMP and the transmembrane ionic currents, it can be shown that in non-dividing cells their high TMP is lowered; whereas in cells with a high division rate, their low TMP is raised due to cell exposure to the external electrical field. These alterations in transmembrane potential could contribute to the normalisation of abnormal cell proliferation.

Animals↗
PubMed1992

Treatment of chronic wounds by means of electric and electromagnetic fields. Part 1. Literature review.

The healing of a cutaneous wound is accompanied by endogeneous electrical phenomena. Not knowing whether they represent merely a side-effect of the physiological processes which take course during healing or whether they play a much more important role as mediators of healing, externally applied electricity was examined as a therapeutic tool for the enhancement of natural regenerative processes. In the present review a historical literature survey dealing with human applications of electric current for wound healing acceleration is given. It presents a complete palette of heterogeneous studies, differing in the parameters of applied electric current, in delivery modes as well as in the types of wounds being stimulated. Because of all these differences, comparing the efficacy of the described methods is difficult and could hardly be objective. Therefore greater stress was laid upon the discussion concerning the problems in designing clinical studies (size of the sample observed, control group, ethics of the procedures), rationales for the employment and possible underlying mechanisms of particular methods, and problems of evaluating their efficacy. In spite of the extensive work performed in the field of electrical wound healing we remain only part way towards explaining the mechanisms by which electricity reinforces the regenerative capabilities of injured tissue as well as only part way towards the selection of the optimal stimulation method from among the published reports.

Chronic Disease↗
PubMed1992

Anti-tumor effect of electrotherapy alone or in combination with interleukin-2 in mice with sarcoma and melanoma tumors.

Electrotherapy with direct current (DC) was performed on two murine tumor models, fibrosarcoma SA-1 and melanoma B16. Three Pt/Ir cathodes were inserted directly into the subcutaneous tumors and two anodes subcutaneously in the vicinity of the tumor. Significant tumor growth delay was achieved after electrotherapy and was dependent on DC intensity (0.6, 1.0, 1.4 and 1.8 mA). Melanoma B16 tumors were more sensitive to electrotherapy than SA-1 tumors. In order to enhance the antitumor effect of electrotherapy, combined treatment with interleukin-2 (IL-2) was performed. When both therapies were combined significant tumor growth delay and also higher curability rate was achieved. The results imply that electrotherapy can be an effective antitumor therapy and that the effects can be enhanced with additional IL-2 therapy.

Animals↗
PubMed1989

FES and spasticity.

A model of hemiplegic spasticity based on electromyographical and biomechanical parameters measured during passive muscle stretching is presented. Two components of spasticity can be distinguished--phasic and tonic. This classification depends on the pattern of stretch reflex activity which can be either phasic or tonic as well as on the muscle stretch/tension characteristic. Stretch reflex, as a control loop, is in phasic spasticity characterized by increased sensitivity to velocity of stretching. In tonic spasticity, sensitivity to length of stretching is increased. After the injury, phasic spasticity appears first and invokes monosynaptic reflex pathways. The intensity of tonic spasticity increases with the duration of disability and hence causes changes in muscle fiber biomechanical properties. The model mentioned above has been used to evaluate the effects of FES on spasticity. Hemiplegic patients with implanted peroneal nerve stimulator for gait correction were followed up for one year starting a week before implantation. Long-term use of FES resulted in decrease of tonic spasticity in both ankle joint antagonistic muscle groups. In stimulated tibialis anterior muscle, the phasic type of spasticity increased. To obtain the correlation between changes in spasticity and functional abilities of patients, the maximal voluntary isometric contraction of both muscle groups was also measured. An improvement in voluntary strength was also observed. This can be taken as additional evidence that tonic spasticity is of greater physiological and clinical significance than phasic spasticity. It may be concluded that use of FES can decrease tonic spasticity and, if applied early after the injury, can prevent the appearance of tonic spasticity.

Adult↗
PubMed1988

Chronic electrical stimulation for the modification of spasticity in hemiplegic patients.

The effects of long-term electrical stimulation on reflex hyperactivity and voluntary muscle control were studied. Eight hemiplegic patients with implanted peroneal stimulator were included. After six months of functional electrical stimulation (FES) there was a decrease of tonic activity in both tibialis anterior and triceps surae muscles. The phasic stretch reflex activity in the stimulated tibialis anterior muscle increased. The resulting resistance during passive movements decreased due to diminution of tonic activity. The absence of tonic activity also resulted in improvement of voluntary control, particularly in the tibialis anterior muscle.

Adult↗
PubMed1988

Electrical stimulation for control of paralysis and therapy of abnormal movements.

After a short review of the functional aspects of electrical stimulation in rehabilitating paralysed patients, the article describes its effects on spasticity. Three different studies are briefly described. In the first one paraplegic patients' knee extensors and flexors were stimulated with four channel stimulator. In the second one two channel stimulation was applied to the ankle joint flexors and extensors in hemiplegic patients, while in the third, the effects of spinal cord stimulation were studied in multiple sclerosis patients. Although the parameters and sites of stimulation were different in each study, the effects were similar. In approximately 50% of paraplegic and hemiplegic patients stimulation caused decrease of reflex activity which lasted more than half an hour. In M.S. patients measurements were performed only in intervals of day and therefore short term effects were not documented. Two days after interruption of continuous spinal cord stimulation the reflex activity significantly increased in the majority of patients. In addition to this increase the volitional force decreased considerably.

Electric Stimulation Therapy↗
PubMed1986

Improved motor response due to chronic electrical stimulation of denervated tibialis anterior muscle in humans.

Nine patients with complete denervation of the tibialis anterior were admitted to a stimulation program in order to restore dorsiflexion of the foot. Best results were obtained with pulses of 20-msec pulse width and 20-msec interval. After 3 weeks of training for 2 X 20 min/day, dorsiflexion due to stimulation was increased in all patients. In some of them, gait could be improved during the swing phase using electrical stimulation. The applied training program thus reversed the course of disuse atrophy and proved the feasibility of functional electrical stimulation for patients with denervated muscles.

Adult↗
PubMed1985

Electrical stimulation in treating spasticity resulting from spinal cord injury.

To study the efficacy of electrical stimulation in treating spasticity of six spinal cord injured patients, transcutaneous electrical nerve stimulation (TENS) was applied to the dermatomes belonging to the same spinal cord level as the selected spastic muscle group. Spasticity was assessed in knee extensors by a pendulum test in which the knee joint angle of a swinging lower leg was recorded with an electrogoniometer. TENS was found to produce a noticeable decrease of spasticity in three of the patients, but had little effect on the others.

Adult↗
PubMed1985

Change in muscle force following electrical stimulation. Dependence on stimulation waveform and frequency.

Change in muscle force in healthy subjects due to electrical stimulation was accomplished with rectangular and sinusoidal currents. The pulse width of rectangular stimuli was 0.3 ms and repetition frequency was 25 Hz. The frequency of sinusoidal stimuli was 2 500 Hz, chopped by a 25 Hz rectangular signal. Thirteen healthy subjects were involved in the study and divided into three groups. The first group (A) had stimulation with rectangular impulses, the second (B) with sinusoidal impulses and the third (C) was a control group. The quadriceps muscle was stimulated daily for 10 minutes for 3 weeks. The maximal voluntary isometric torque increased for 25% in group A and 13% in group B, while there was no significant difference in group C. Different patterns of fatigue occurred with different stimuli. The presence of fatigue during the high frequency sinusoidal stimulation diminished the strengthening effects.

Electric Stimulation↗
PubMed1984

Pendulum testing of spasticity.

Simple and inexpensive instrumentation required for pendulum testing of spasticity is described. It is based on the use of an electrogoniometer and tachometer. Eight parameters are extracted from the goniogram and the tachogram to evaluate the degree of spasticity. The correlation coefficients are calculated to determine the parameters relevant for the estimation of spasticity. Spasticity was assessed in the knee extensors of ten spinal cord injury patients and in five hemiplegics. The described instrumentation and evaluation of the pendulum test provide an effective spasticity testing in the clinical environment.

Adult↗