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Biomedical subjects

J Kundrát

Publications and source records attributed to J Kundrát.

At least 19 recordsLinked to original sources
PubMed1994

Differences in saccadic eye movement-related potentials under regular and irregular intervals of visual stimulation.

The saccadic eye movement-related potentials (SEMRPs) were recorded over various brain areas in a group of righthanders while they performed saccades to visual stimuli appearing either at regular or at irregular time intervals. The premotion positivity, motion execution component and lambda responses were of shorter latencies and lower amplitudes over the parietal areas as compared to the occipital ones. This finding did not depend on the regularity of intervals. With regular intervals, the positive wave starting before and peaking at the end of a saccade was found over the frontal eye fields. With irregular intervals, the premotion negativity was registered over the motor and frontal cortices. With saccades at regular intervals, the oculomotor components in the SEMRPs were less pronounced as compared to the irregular ones. These results are in accordance with the presumption that visual stimuli, appearing at irregular intervals, require higher attention and readiness to the oculomotor reaction, respectively, and also with the supposed role of the right hemisphere of righthanders in processing visual information.

Adult↗
PubMed1992

[Computer analysis of muscle reflex responses to electric stimulation of peripheral nerves].

A computer program is described which allows analysis of reflex muscle responses to electric stimulation of peripheral nerves. Basically, the program is derived from an older methodic approach, yet the process of evaluating the obtained means of reflex muscle responses is in this computer assisted procedure simpler and of a higher quality. The proposed improvement of the original methodic approach provides an important advantage for clinical practice in significantly speeding up the investigation and evaluation of reflex muscle responses on using financially accessible computer technique of Czechoslovak make. The paper points out the possibility of using the program also for analysis of other biological signals and of adjusting it for more efficient types of personal computers.

Electric Stimulation↗
PubMed1990

[Physiologic range of stabilometry values obtained in the upright posture using a computer].

The authors present physiological ranges of values of seven parameters of stabilometric examinations of the upright posture in man. In order to make the examination effective, the authors suggested and tested three situations which make it possible to characterize the activity of the visual, vestibular and proprioceptive feedback in the process of maintenance of the upright posture. For measuring the supporting forces during the upright posture the authors used a stabilometer with automatic compensation of the body weight. Amplitude analysis of the obtained stabilometric curves was made "on line" by means of a microcomputer PMD 85-2. The mentioned stabilometric parameters make it possible to evaluate objectively the ability of the subject to maintain an upright posture based on a) the median amplitude and velocity of deviations of the body in an anterioposterior and lateral direction, b) complex parameters of the length of the curve, the total area and root mean square deviation of the statokinezigram.

Adult↗
PubMed1989

[Use of Septopal in the treatment of bone infections].

The authors evaluate a group of 29 patients where they used during treatment of a bone infection gentamicin pellets--Septopal Merck. The mean age of the patients was 46.6 years (9-75 years) the mean duration of the symptoms of inflammation before operation was 20 months. The prerequisite of successful application of Septopal is radical surgical treatment of the site of infection and provision of high standard soft tissue covering and assessment of the sensitivity of the aetiological agent to gentamicin. The most frequent causal agent of infection was Staphylococcus aureus in 48.3% and in combination with Gram-negative rods in 34.5%. In infections of total prostheses of joints one of the pathogenic agents was also Staphylococcus epidermidis. Healing per primam was recorded in 41% per secundam in 28%, in general, treatment was successful in 69%. By application of Septopal high local bactericide concentrations of gentamicin can be achieved for three months without threatening the patient with toxic side effects--local or general. The authors recommend, however, to remove it after cca 8 weeks.

Adolescent↗
PubMed1985

Activity changes in nucleus reticularis gigantocellularis in relation to skilled forelimb movement in rats.

Adult hooded rats were trained to reach for food pellets into a narrow plexiglass tube and the movement of the preferred forelimb was photo-electrically detected. Multiple unit activity (MUA) or single unit activity in n. reticularis gigantocellularis (NGC) was recorded during reaching. Depression of MUA was observed about the onset of the forepaw movement and lasted during its execution. There was a correlation between MUA changes and the depression of activity of individual neurons observed in a part of NGC.

Action Potentials↗
PubMed1984

Ensemble reactions of neurons in the reticular formation of the cat--categorization of inputs and temporal influences.

A method of recording ensemble reactions of reticular neurons was applied in anesthetized cats to obtain information about categorization of inputs and the influence of the time factor upon a pattern of responses, reactions to stimulus intensity changes and to complex stimuli, and temporal influences with their relation to plastic changes induced by iterative stimulation. In spite of some variability of the pattern of responses evoked in the reticular formation (RF) by electrical stimulation of the same source, reactions of the parenchyma of the RF differentiate heterotopic stimuli; reactions evoked from receptor areas situated closely to each other exhibited a similar pattern whereas less resemblance was found in the case of responses evoked from sources with a heterosegmental projection and from contralateral sources. Stimulus intensity changes did not influence substantially the pattern of recordings in the RF. The noticeable effect resulting from the increase of stimulus intensity was enlargement of responses. A complex stimulus (two heterotopic stimuli applied simultaneously) was manifested by a reaction which, in comparison with reactions evoked from each of both sources separately, had a different pattern. A trend of changes in the size of responses evoked in the RF by continuous stimulation (60 stimuli, 0.3 Hz) was observed only in some cases. Abrupt alterations of the stimulation rate (0.3 Hz in equilibrium 1 Hz, 0.3 Hz in equilibrium 2 Hz) resulted in a prompt change in responses. With constant stimulation conditions, this activity was fairly constant with an absence of trends. Persistent changes were observed only in a minority of cases. The neuronal apparatus of the RF computes ongoing effects on the basis of ability to discriminate different inputs and to readily change its function. The extent to which the RF holds information about the antecedent "history" of its functioning and the extent to which intrinsic mechanisms of the RF by itself are responsible for behavioral habituation remains problematical.

Animals↗