Biomedical subjects

I Papousek

Publications and source records attributed to I Papousek.

8 recordsLinked to original sources

PubMed2006

[Mutational analysis of LQT genes in individuals with drug induced QT interval prolongation].

BACKGROUND: In a long list of non-cardiovascular drugs a risk of QT interval prolongation and thus an increased risk of malignant arrhythmias has been described. The precise mechanism remains unclear. Many of these drugs are potent blockers of cardiac ion channels. Thus, prolongation of repolarization could be caused by latent ion channel genes mutations which are revealed under stress conditions. GROUP OF PATIENTS AND METHODS: Patients were recruited in screening of antipsychotic drugs with proarrhythmic potential, another sporadic cases were reffered from regional hospitals. In 13 individuals pathologic values of corrected QT interval (> 0.44 s in males, > 0.46 s in females) were observed. Eleven patients gave their consent to mutational analysis of KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2 and KCNJ2 genes (associated with congenital long QT syndrome). RESULTS: At present complete results of mutational analysis are available in 8 patients. In 5 individuals changes in DNA sequence were found which are considered normal variants according to the literature (nucleotide and aminoacid polymorphisms, intronic variants). In 1 male a KCNQ1 gene mutation A590T was identified (yet not reported in literature). CONCLUSION: Mechanisms of drug-induced QT interval prolongation is complex and it cannot be explained simply by ion channel disorders.

DNA Mutational Analysis↗

PubMed2006

[Extension of QT interval as a consequence of risk factor accumulation--case study].

BACKGROUND: Many non-cardiovascular drugs have a potential for QT interval prolongation. This phenomenon can be related to occurence of ventricular tachycardia torsades de pointes, syncopi and even sudden death. DESCRIPTION OF THE CASE: A female patient treated with antracycline cytostatics developed a depression of left ventricle ejection fraction. At the same time she was administered 2 common drugs with proarrhythmic potential--terfenadine and itraconazole. In this patient hypokalemia also occured. Combination of the above mentioned risk factors led to QT interval prolongation and frequent ventricular tachycardias torsades de pointes degenerating in ventricular fibrillations with need of repeated defibrillations. Both drugs were withdrawn and dysiontaemia corrected. Then arrhythmias disappeared and QT interval completely normalized. In this patient the congenital long QT syndrome was not proved. DISCUSSION AND CONCLUSIONS: In proarrhythmic effect of non-cardiovascular drugs the following factors play role: predisposition of a particular individual, "repolarization reserve", interindividual differences in drug metabolism. The risk factors are age, sex, dysiontaemia, heart disease and drug interactions. By different choice of medication and attention to risk factors teh life threat to the described patient could have been avoided.

Adult↗

PubMed2001

Associations between EEG asymmetries and electrodermal lability in low vs. high depressive and anxious normal individuals.

In order to investigate one aspect of cortical-autonomic control, cortical activation asymmetries, measured by EEG, were related to activity of the sympathetic nervous system, measured by EDA (electrodermal lability, number of spontaneous fluctuations), in two large samples. Since it may help to explain the participation of psychological factors in the development of various somatic complaints and disorders, we examined whether inter-individual differences in autonomic nervous system regulation may exist that are related to stress/anxiety and depression within the normal range. Results demonstrate substantial modifications of functional hemisphere asymmetries in the modulation of EDA by these emotional factors and suggest that activation asymmetries in orbital and dorsolateral frontal regions reflect two different cortical sub-systems regulating electrodermal activity. The findings may, to some extent, provide an explanation for contradictory results in previous studies and may encourage research in psychosomatics and other clinical fields (e.g. schizophrenia).

Adult↗

PubMed1999

Quantitative assessment of five behavioural laterality measures: distributions of scores and intercorrelations among right-handers.

Five behavioural laterality measures (degree of right-handedness, ear dominance, ocular dominance, line bisection performance, and lateral preference as assessed by preferred direction of conjugate lateral eye movements) were analysed in 1171 right-handers by merging data from 15 different samples. All laterality aspects were assessed quantitatively by using well controlled performance measures instead of questionnaires. The distributions and intercorrelations of the measures as well as their test-retest reliabilities were examined. Results show moderately high reliabilities for all measures, and clearly demonstrate considerable variability among dextrals in the direction and magnitude of the obtained behavioural laterality measures. Most importantly, independence of the different measures questions some common assumptions in laterality research. It seems unlikely, for instance, that handedness and other aspects of laterality may be a product of one single underlying mechanism of brain lateralisation.

Journal Article↗

PubMed1999

EEG correlates of behavioural laterality: right-handedness.

Among right-handers, the magnitude of differences in proficiency between the left and right hands varies considerably. Yet significance of the extent of right-handedness is still a controversial issue. To examine whether individual differences in asymmetry of hand skill can partly be attributed to individual differences in asymmetrical hemispheric activation, handedness and electroencephalographic (EEG) laterality were correlated in two large samples (ns = 60 and 128). Analysis indicated that part of the variability in right-handedness may arise from activation asymmetries in the cortex, but whether this relation becomes apparent depends on the cortical area examined and on the experimental condition under which the EEG measures are taken.

Adolescent↗

PubMed1998

Bilateral electrodermal activity: relationships to state and trait characteristics of hemisphere asymmetry.

Influences of trait and state characteristics of individual brain lateralization on bilateral electrodermal activity (EDA) were examined. EDA was observed in two different recording conditions: (1) non-specific skin conductance responses (ns.SCRs) were obtained during a stimulus-free recording period of 5 min; and (2) stimulus evoked skin conductance responses (SCRs) were elicited by 80 dichotically presented pairs of pure tones which--at the same time--constituted the items of a test to estimate subject's lateral ear dominance. In addition to ear dominance, degree of right-handedness and hemispheric preference, i.e. preferred direction of conjugate lateral eye movements (CLEMs) were assessed as trait-like characteristics of individual laterality. With respect to asymmetry of ns.SCRs, no effects of the laterality variables were observed. Analysis of SCRs, however, resulted in significant interactions of ear dominance and hemispheric preference with degree of right-handedness indicating higher SCR amplitudes on the hand contralateral to the preferred hemisphere in strong dextrals. Weak right-handers showed a different pattern of bilateral asymmetries, partly in the opposite direction. Additionally, phasic effects of cortical asymmetry on SCRs seem to be modified by trait characteristics of individual laterality. Results underline the importance of precisely controlling degree of handedness in studies of bilateral electrodermal activity. Furthermore, the observed effects support the assumption of cortical influences on EDA, but argue against the existence of a single cortical mechanism modulating asymmetries in the electrodermal system.

Adolescent↗

PubMed1998

Different temporal stability and partial independence of EEG asymmetries from different locations: implications for laterality research.

In order to investigate a possible regional specificity of activation asymmetries of different parts of the cortex and the stability of these asymmetries across time and conditions, EEG was recorded during rest and stimulation conditions in a large sample of right-handed university students (n = 60). Recordings were made in two sessions (interval between sessions 2-4 weeks). In the first session two rest periods were conducted (interval 30 min) and one under stimulation. In the second session EEG was again recorded at rest. Reliability analyses show that the long-term stability of orbitofrontal asymmetries is markedly lower than that of dorsolateral, temporal, and parietal scores. Intercorrelations of EEG asymmetries at different electrode positions suggest that anterior and posterior EEG asymmetries are largely independent measures of cortical laterality. Both this partial independence of activation asymmetries and the differences in temporal stability underscore the significance of the anterior-posterior dimension in laterality research and may be one reason for several contradictory observations in studies on brain laterality.

Acoustic Stimulation↗

PubMed1992

Bilateral electrodermal activity: reliability, laterality and individual differences.

A first aim of the present study was to estimate the short- and long-term stability of individual response patterns in bilateral electrodermal activity (EDA). A second aim was to examine the relationship of individual brain laterality to both peak amplitude and peak time based electrodermal asymmetry. Additionally, subjects were presented with verbal and spatial tasks to estimate the balance of left/right asymmetry in cerebral activation at time of testing. Finally, the influence of smoking, coffee consumption and subjective circadian phase (morningness/eveningness, subjects' rise time) on bilateral asymmetry and EDA lability was examined. Results indicated moderate to high short-term reliabilities of EDA laterality coefficients, but insufficient long-term stability. Handedness and conjugate lateral eye movements (CLEMs) were not related to asymmetry of EDA, but a significant interaction between CLEM tendency and smoking/nonsmoking on laterality of both EDA parameters was observed. Amount of coffee consumption was also significantly related to electrodermal asymmetry. Analysis of performance data demonstrated that intraindividual shifts of EDA laterality from one recording session to a following one were associated with corresponding shifts in accuracy of verbal/spatial performance. Degree of subjects' electrodermal lability differentiated significantly between speed and accuracy of performance in both verbal and spatial tasks, and was substantially related to subjects' rise time.

Adolescent↗