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Biomedical subjects

H Giedke

Publications and source records attributed to H Giedke.

At least 37 records · Page 2Linked to original sources

Slow brain potentials and psychomotor retardation in depression.

Event-related cortical potentials were recorded in 11 patients with primary depression and 11 healthy control subjects during a serial choice reaction task. Each new trial was voluntarily initiated when the subject pressed a microswitch; an acoustic go or no-go signal followed after a fixed interval. This elicited a Bereitschaftspotential (BP), a contingent negative variation (CNV), acoustically evoked potentials (N1, P2, P3), and a post-imperative negative variation (PINV) in direct succession. These were evaluated conventionally and by principal component analysis (PCA). Patients exhibited significantly longer reaction times and more negative PINVs. BP and CNV did not differ between groups. In conventional amplitude measurement small P3 amplitudes in depressives may be feigned by markedly negative PINVs.

Adult↗

Lithium suppresses hibernation in the Turkish hamster.

Daily uptake of lithium salt (LiCl) in the drinking water at a rate of over 100 micrograms/g b.wt (or 2.4 mEq/kg) reduced or suppressed natural torpidity (hibernation) in the Turkish hamster (Mesocricetus brandti). The data indicate a direct influence of lithium on clock-related functions controlling the hibernation process rather than indirect effects by preventing gonadal regression and thereby also hibernation.

Animals↗

Plasma levels, psychophysiological variables, and clinical response to amitriptyline.

Hamilton depression scale ratings and physiological measurements were made for 37 patients with primary depression before treatment with amitriptyline (150 mg/day) and again after 2 and 4 weeks of treatment; plasma drug levels were determined weekly. Improvement was maximal at mean amitriptyline + nortriptyline concentrations of 125-200 ng/ml (14 patients), while at lower levels the outcome was significantly poorer (12 patients). Highly variable results were seen in 11 patients with levels between 200 and 301 ng/ml, with lesser improvement occurring in those patients who exhibited poor habituation of the skin resistance response before treatment. Other psychophysiological variables showed significant changes during treatment, but no correlation with clinical results or drug levels.

Adult↗

Diurnal variation of urinary MHPG in unipolar and bipolar depressives.

In eight bipolar depressives, 11 unipolar depressives, and 15 healthy controls urinary excretion of MHPG was measured at 3-h intervals over one 24-h period. Bipolars excreted smaller amounts of MHPG than unipolars and controls, especially at night. MHPG excretion was significantly dependent on time of day in the control group only. In the patients maximum excretion showed a tendency to occur earlier in the day than in controls. Minima were unaffected. There were indications that tricyclic antidepressants advance MHPG phases.

Adult↗

The relationship between P3-latency and reaction time in depression.

A random series of frequencies and infrequent clicks was presented to 13 primary depressives and 13 healthy controls matched for age and gender. Subjects were instructed to press a button as fast as possible in response to the infrequent clicks. P3 amplitudes and latencies as well as correlations between P3 latency and reaction time were calculated on a single trial basis using Woody's adaptive filter. While reaction times were significantly longer in patients, neither P3 latencies nor P3 amplitudes differed between the groups. Thus, delayed reaction time of depressives seems to be a consequence of impaired selection, activation, or execution of the motor response rather than of delayed stimulus evaluation. The correlation between P3 latency and reaction time was significantly smaller in patients then in controls.

Adult↗

Controllability of an aversive stimulus in depressed patients and health controls: a study using slow brain potentials.

Slow brain potentials (CNV and PINV) were recorded from 18 patients with primary depression and 18 health controls under three experimental conditions. A short tone (S1) indicated the occurrence of an aversive tone stimulus (S2) which could not be terminated by a motor reaction in Condition 1 (C1) but was terminated in C2. In C3 the reaction time (RT) had to be faster than the shortest mean RT from C1 and C2 in order to stop the aversive stimulus. For both groups the RT decreased from C1 to C2 to C3 and the CNV increased from C2 to C3. CNV and RT did not differ between the groups in either condition. In C1 and C3 (uncontrollability and restricted control over the aversive stimulus) patients developed a marked PINV which was not observed in the control group. In view of other investigations which found a PINV in normal subjects in situations of sudden, unexpected uncontrollability, the present results demonstrate that depressed patients are more sensitive to levels and variation of uncontrollability than healthy subjects. A possible relationship to Seligman's concept of helplessness is discussed.

Arousal↗

Evoked potentials, expectancy wave, and skin resistance in depressed patients and healthy controls.

Averaged evoked potentials, expectancy waves and number and amplitude of skin resistance responses to auditory stimuli are found to be significantly smaller in a group of 18 patients with primary depression than in 27 healthy controls. AEP amplitude attenuation is shown not to be an averaging artifact, due to varying response latencies. There are no simple relations between electrocortical and electrodermal parameters, but patients display more significant correlations between these two sets of variable than controls. Amplitude attenuations are interpreted as hyporesponsivity resulting from depressive inhibition. The narrower coupling of variables in the depressed group is viewed as a limitation in physiological plasticity.

Acoustic Stimulation↗

[Measurement of body temperature in the auditory canal or in the rectum: first experience with a device for continuous registration of body temperature of psychiatric patients (author's transl)].

A method for continuous measurement of body temperature over a 24-h period is presented. the temperature is measured by an active sensor placed in the external auditory canal or in the rectum, and stored on a magnetic tape in a portable cassette recorder weighing 400 g. Rectal temperature is less sensitive to environmental influence and easier to record than ear temperature. With this method possible disturbances of the diurnal temperature rhythm in psychiatric patients can be registered.

Body Temperature↗

Dissecting aneurysm of the petrous portion of the internal carotid artery. Case report and review of previous cases.

A "spontaneous" dissecting aneurysm of the petrous portion of the right internal cartoid artery in a 60 year old man was demonstrated angiographically. It showed a typical double lumen which is rarely demonstrated by angiography. It was probably of atherosclerotic origin. In addition, a survey of the positions and angiographic characteristics of the 29 traumatic and "spontaneous" dissecting aneurysms of the common and internal carotid arteries found in the literature is presented.

Carotid Artery, Internal↗