Biomedical subjects

P Jähnig

Publications and source records attributed to P Jähnig.

11 recordsLinked to original sources

PubMed1999

Effect of two antidepressant drugs on REM sleep and EMG activity during sleep.

In a placebo-controlled study, the effects on sleep of single and repeated doses of imipramine and dexnafenodone, an antidepressant drug under development, were investigated in young, healthy volunteers. In contrast to placebo, both drugs suppressed REM sleep substantially after acute and repeated administration. As a consequence, REM sleep latencies increased under active treatment to mean values which were about two to four times larger than baseline values. Since the active inhibition of the muscle tone is a distinct feature of REM sleep, we studied the influence of the two antidepressant drugs on this variable. By means of computerised EMG analysis, tonic and transient EMG activity were computed for total recording time and for the different sleep stages. While tonic EMG activity during sleep was increased with both drugs, transient EMG events remained unaffected. Computerised analysis of the microstructure of sleep is an effective tool for studying the effect of antidepressant drugs on sleep.

Adrenergic Uptake Inhibitors↗

PubMed1995

Methodological considerations for the evaluation of EEG mapping data: a practical example based on a placebo/diazepam crossover trial.

Quantitative EEG is a sensitive method for measuring pharmacological effects on the central nervous system. Nowadays, computers enable EEG data to be stored and spectral parameters to be computed for signals obtained from a large number of electrode locations. However, the statistical analysis of such vast amounts of EEG data is complicated due to the limited number of subjects usually involved in pharmacological studies. In the present study, data from a trial aimed at comparing diazepam and placebo were used to investigate different properties of EEG mapping data and to compare different methods of data analysis. Both the topography and the temporal changes of EEG activity were investigated using descriptive data analysis, which is based on an inspection of patterns of pd values (descriptive p values) assessed for all pair-wise tests for differences in time or treatment. An empirical measure (tri-mean) for the computation of group maps is suggested, allowing a better description of group effects with skewed data of small samples size. Finally, both the investigation of maps based on principal component analysis and the notion of distance between maps are discussed and applied to the analysis of the data collected under diazepam treatment, exemplifying the evaluation of pharmacodynamic drug effects.

Adult↗

PubMed1995

ECG activity in the sleep of insomniac patients under the influence of lormetazepam and zopiclone.

The influence of the benzodiazepine hypnotic lormetazepam (1 mg) and the cyclopyrrolone hypnotic zopiclone (7.5 mg) on heart rate activity was studied in 16 elderly insomniacs in a placebo-controlled, randomised, 3-fold crossover trial. After digital preprocessing of the ECG, QRS complexes were automatically recognised by a detection technique based on adaptative thresholds. Both R-R periodicity and heart rate variability were analysed as a function of sleep stages and time of night. Under placebo, heart rate decreased significantly from the first to the second half of the night. The relationship between sleep stages and heart rate remained constant under both hypnotics. Although the two substances significantly modified the distribution of sleep stages, no relevant changes in ECG activity were observed when the proportion of the different sleep stages was taken into consideration.

Aged↗

PubMed1995

On the choice of recording duration in pharmaco-EEG studies.

Quantitative EEG is a sensitive method used to assess the effects of pharmacological substances on the central nervous system (CNS) activity. A standard technique is to measure the EEG under vigilance-controlled and resting conditions for a short duration, for example 5 min. The aim of the present study was to investigate the stability of 5-min EEG recordings. While the time course of the EEG was fairly stable during the recording session under the vigilance-controlled condition, systematic trends became apparent under the resting condition. Pharmaco-sensitivity of the EEG and its reliability increased with the recording duration. Five minutes of EEG recording seem to be sufficient and well chosen to evaluate the influence of drugs on the EEG.

Adult↗

PubMed1994

A computerized method for detecting episodes of wakefulness during sleep based on the alpha slow-wave index (ASI).

A method for the automatic detection of episodes of wakefulness during sleep is presented. The algorithm is based on the evaluation of the alpha slow-wave index (ASI), a measure that has been developed to detect fluctuations of vigilance in daytime pharmaco-electroencephalogram studies. Its application to sleep data was validated with polysomnographic recordings from 16 elderly insomniacs and 16 young healthy subjects. The rate of agreement between the computerized procedure and the visual scoring of wakefulness was 94.0% for the insomniacs and 96.9% for the healthy subjects. The decision criterion used by the computer allowed the definition of a subject-adapted threshold for the detection of wake episodes. The method opens new perspectives for the automatic analysis of continuous 24-hour sleep-wake recordings.

Aged↗

PubMed1993

A comparison between visual and computer assessment of sleep onset latency and their application in a pharmacological sleep study.

Sleep onset latency (SOL) is frequently defined as the time between lights-out and the first epoch of sleep stage 2. In practice, SOL can be quantified easily on the basis of visual examination. We have developed a computer algorithm allowing an automatic estimation of this parameter. The agreement between both strategies, visual and computer analysis, was tested using data from a pharmacological sleep study with 16 elderly insomniacs, which was aimed at comparing the effects of lormetazepam and zopiclone on polysomnography. A high correlation was found between the visual and the computer-based determination of SOL. Drug-related differences in SOL could be shown with both approaches.

Aged↗

PubMed1992

Terguride stimulates locomotor activity at 2 months but not 10 months after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treatment of common marmosets.

The mixed dopamine (DA) agonist/antagonist terguride acts as a DA antagonist on normosensitive receptors but shows DA agonistic properties at supersensitive DA receptors. Such a compound could offer an alternative to the treatment of Parkinson's disease with indirect or direct DA agonists. The present study compares the actions of terguride, 4-12 mg/kg i.p., in naive common marmosets with its effects in animals rendered parkinsonian by administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 2 months or 10 months previously, in order to test its antiparkinsonian efficacy. Terguride reduced locomotor activity in naive common marmosets, similar to its effects in rodents and in line with the DA antagonistic activity of the compound. In marmosets treated with MPTP 2 months previously and exhibiting pronounced behavioural motor deficits, terguride stimulated locomotor activity, showing DA agonistic properties under these conditions. In contrast, the locomotor activity of animals that had recovered from MPTP treatment 10 months previously was not altered by terguride. It is concluded that terguride has anti-akinetic efficacy in this primate model of Parkinson's disease. In addition, terguride offers a unique opportunity to differentiate, pharmacologically, the extent of dopaminergic recovery from MPTP treatment in this primate species.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1992

Motor activity following the administration of selective D-1 and D-2 dopaminergic drugs to MPTP-treated common marmosets.

The ability of selective D-1 agonist and antagonist drugs to alter motor deficits and locomotor activity was studied in MPTP-treated common marmosets. Both the D-2 agonist quinpirole and the mixed D-1/D-2 agonist apomorphine reversed the motor impairments and induced locomotor activity. The D-1 antagonist SCH 23390 and the D-2 antagonist raclopride given alone further reduced motor function in MPTP-treated animals. The actions of quinpirole were potently and completely inhibited by raclopride but only partially and inconsistently by SCH 23390. In contrast, the effects of apomorphine were markedly but incompletely inhibited by both raclopride and SCH 23390. The D-1 agonist SKF 38393 alone caused a dose related reduction in motor activity. SKF 38393 weakly and partially inhibited the improvements in motor function produced by quinpirole but had a more pronounced effect on apomorphine induced motor activity. The induction of motor activity in MPTP treated common marmosets may separately involve both D-1 and D-2 receptors. Comparison with our previous data on the effect of the same drugs in normal common marmosets provides some evidence for a breakdown of linkage between D-1 and D-2 systems following MPTP treatment. The actions of SKF 38393 in MPTP-treated common marmosets contrasts with its ability to induce behavioural activation and a facilitation of D-2 mediated behaviour in rodents. SKF 38393 may not be the compound with which to delineate the role of D-1 receptors in primates.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1992

Pattern recognition by matched filtering: an analysis of sleep spindle and K-complex density under the influence of lormetazepam and zopiclone.

The evaluation of sleep EEG patterns is mostly accomplished by visual analysis. With modern personal computers however, it is possible to perform signal detection within a reasonable length of time automatically. This paper presents a method for signal processing based on matched filtering. This allows the detection of sleep spindles and K-complexes in a sleep EEG recording with a high degree of accuracy. First the technique is described, and the results of a validation study based on the comparison of visual evaluations and computer analysis are presented. Thereafter, results of an application study are presented. Sleep spindle and K-complex density under the influence of lormetazepam and zopiclone were examined. Under both medications sleep spindle density increased while K-complex density decreased. Computation of Pearson's correlation coefficients demonstrated that the interindividual sleep spindle and K-complex variations under both treatments are highly correlated. The data suggest that lormetazepam and zopiclone, although chemically different, have a similar mode of action and display comparable effects on the sleep EEG.

Adult↗

PubMed1992

Topographical analysis of sleep spindle activity.

There is evidence for two types of sleep spindle activity, one with a frequency of about 12 cycles/s (cps) and the other of about 14 cps. Visual examination indicates that both spindle types occur independently, whereby the 12-cps spindles are more pronounced in the frontal and the 14-cps spindles in the parietal region. The purpose of this paper is to provide more information about the exact topography of these patterns. First the occurrence of distinct signals in anterior and posterior brain regions was verified using pattern recognition techniques based on matched filtering. Thus the existence of two distinct sources of activity located in the frontal and parietal region of the brain, respectively, was demonstrated using EEG frequency mapping. Evaluation of sleep recordings showed high stability both in the frequency and location of the presumed spindle generators across sleep. Pharmacological effects of lormetazepam and zopiclone on both spindle types were investigated. Both substances enhanced the sleep spindle activity recorded from the frontal and parietal electrodes, but this increase was more pronounced in the parietal brain region.

Adult↗

PubMed1991

Synergism of the AMPA-antagonist NBQX and the NMDA-antagonist CPP with L-dopa in models of Parkinson's disease.

Degeneration of dopaminergic nigrostriatal neurons in Parkinson's disease results in an overactivity of excitatory glutamatergic projections from the subthalamic nucleus to the output nuclei of the basal ganglia resulting in rigidity and akinesia. In theory pharmacological blockade of these overactive systems should improve parkinsonian symptomatology. The selective AMPA-antagonist NBQX and the competitive NMDA-antagonist CPP are not effective in animal models of Parkinson's disease when given alone but ameliorate parkinsonian symptomatology and stimulate locomotor activity when co-administered with a threshold dose of L-Dopa. These synergistic effects are seen in the MPTP-treated (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) common marmoset and the rat with unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra. Therefore competitive NMDA and non-NMDA antagonists may offer a new therapeutic strategy for the treatment of Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗