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Biomedical subjects

G Debus

Publications and source records attributed to G Debus.

At least 19 recordsLinked to original sources
PubMed2006

The neural basis of ego- and allocentric reference frames in spatial navigation: evidence from spatio-temporal coupled current density reconstruction.

Different strategies in spatial navigation during passages through computer-simulated tunnels were investigated by means of EEG source reconstruction. The tunnels consisted of straight and curved segments and provided only visual flow, but no landmark, information. At the end of each tunnel passage, subjects had to indicate their end position relative to the starting point of the tunnel. Even though the visual information was identical for all subjects, two different strategy groups were identified: one group using an egocentric and the other group an allocentric reference frame. The current density reconstruction revealed the use of one or the other reference frame to be associated with distinct cortical activation patterns during critical stages of the task. For both strategy groups, an occipito-temporal network was dominantly active during the initial, straight tunnel segment. With turns in the tunnel, however, the activation patterns started to diverge, reflecting translational and/or rotational changes in the underlying coordinate systems. Computation of an egocentric reference frame was associated with prevailing activity within a posterior parietal-premotor network, with additional activity in frontal areas. In contrast, computation of an allocentric reference frame was associated with dominant activity within an occipito-temporal network, confirming right-temporal structures to play a crucial role for an allocentric representation of space.

Adult↗
PubMed2006

[Prenatal care and the family doctor].

The general physician faced with the task of providing a pregnant patient with medical care must comply with the same legal guidelines as the gynecologist. In accordance with these regulations, 10 medical examinations are mandatory during a normal pregnancy. In addition to general counseling, these comprise three ultrasonic and various laboratory investigations at predetermined time points. In addition, an oral glucose tolerance test is recommended. With the aim of detecting risk factors in good time, a comprehensive history is essential. If a risk pregnancy is identified,the patient must be referred to the care of a gynecologist.

Chlamydia Infections↗
PubMed2003

[Peri- and postmenopausal changes--body awareness, sexuality, and self- image of the middle-aged and older woman].

UNLABELLED: INTRODUCTION, METHODS: For the first time a study has been made, in a German urban population, of sexuality, body awareness and self-image of women between 50 and 82 years. A special anonymous questionnaire was designed by female gynaecologists and psychologists for this cross-sectional study in Munich. It focuses on body awareness, self imagery, sexual activity and psychological and physiological sexual feeling in their biographic context. 102 women took part. RESULTS: 53.9% are sexually active and 74.5% think of themselves as "a knowing woman", "middle aged" or "in the best years". Self perception of the body as being attractive correlates highly significantly with the psychological well-being. There is no correlation between women's psychological well-being and the perception of their general beauty. Women who find their body attractive think of themselves as more sensual than those, who do not find their body attractive. General and bodily perception of beauty are negatively correlated to the body mass index. Here, 61.8% of the women think they are overweight, but only 41.2 % have a body mass index over 25. 12.9% were sexually abused, and another 8.8% do not want to answer this question. There is a strong correlation between fear and sexual abuse. Only about 50% of the women speak about their sexuality and, of them, only 9.8% speak with their gynaeclologist. CONCLUSION: Sexuality is very important for the middle-aged and older woman, their body perception is as sensitive as in younger women and is of enormous importance for their psychological well-being. A Sexual history should be obligatory for older women. Fear of the examination can be a hint towards sexual abuse and should be taken seriously. All therapeutic interventions such as medication or operations should be discussed, and the patient's sexual wishes and expectations have to be taken into consideration.

Aged↗
PubMed2001

[The "tunnel task": a method for examination of cognitive processes in spatial orientation performance].

We report on the theoretical development and empirical testing of a new spatial cognition task, during which participants complete a tour through a virtual tunnel. Upon arrival they are asked to specify a "homing" vector by pointing an arrow towards the starting point of their virtual journey. Systematic experimental variations include number, length and sharpness of turns. Solving the task requires the development of a spatial representation, as alternative strategic cues (e.g., visual landmarks) are not available. Performance measures discriminate between general training effects and specific task variables. As an example, "side errors" indicate a loss of orientation and "position hits" reflect the accuracy of the spatial representation. Participants use either an egocentric or allocentric frame of reference. The task does not imply the use of egocentric vs. allocentric spatial co-ordinates, yet it allows for a reliable a-priori identification of individually preferred strategies. Our data indicate that the spatial representations formed by both groups are functionally equivalent. However, the groups differ with respect to specific patterns of orientation errors.

Adult↗
PubMed1998

Saccadic velocity and activation: development of a diagnostic tool for assessing energy regulation.

The hypothesis was tested that peak velocity of saccadic eye movements in visual motor tasks varies with variables related to energy regulation. The hypothesis is based on the cognitive-energetical performance model of Sanders. An experimental paradigm was developed in which saccadic peak velocity of task-relevant eye movements is measured while a choice reaction task is carried out. Confounding factors of saccadic amplitude and movement direction were controlled. The task was designed in such a way that in each trial subjects performed a target saccade towards an imperative stimulus and a return saccade after the manual response back to the centre of the screen. For both types of saccades the experimental variables were foreperiod duration (short versus long), knowledge of results (with versus without), postsaccadic demand (low versus high) and time on task (five 30-min intervals). In two experiments, there are main and interaction effects of the task variables on peak saccadic velocity. Return saccades are slower than target saccades, but not in the case of high postsaccadic demand. Knowledge of results increases peak saccadic velocity, but more so for return than for target saccades. Time on task leads to a decrease in peak saccadic velocity, which is much stronger for return than for target saccades; furthermore this effect is more pronounced after short than after long foreperiods. Peak saccadic velocity is changed within seconds. The results support the hypothesis. Peak saccadic velocity of task related eye movements reflects energy regulation during task performance. The paradigm will be developed as a diagnostic tool in workload measurement.

Adult↗
PubMed1994

Temporal coordination of alternative and simultaneous aiming movements of constrained timing structure.

Two experiments are reported addressing the preparation and initiation of movements with equal or unequal timing properties for both hands. Temporal coordination was examined in two movement tasks: one in which both hands performed the movements simultaneously (simultaneous aiming task) and one in which only one alternative of two possible movements was executed (choice aiming task). For each task a different group of subjects was used. Besides the timing relationships between both movements, the effects of preparation interval (1, 3, and 5 s), the average velocity (7, 14, 17.5, and 70 cm/s), the presence of advance information about the required velocity of the movement(s), and practice were investigated. Based on the common- and the specific-timing notions, distinct hypotheses were tested as to the effects of the variables on the temporal coordination as revealed by reaction time. A main result was that the effects of timing differences between the hands was task specific. For the choice task the data are in agreement with the common-timing notion of coordination, i.e., only one timing demand at a time can be prepared, whereas in the simultaneous task evidence was obtained for the specific-timing notion, i.e., independent preparation and initiation of different timing properties for the hands. However, it is argued that the results of the choice task probably do not reflect a general inability to prepare movements of different timing requirements for both hands, but is related to a task-specific strategy of selective preparation.

Adult↗
PubMed1985

Effects of rolipram, a novel antidepressant, on monoamine metabolism in rat brain.

The phosphodiesterase inhibitor and putative antidepressant rolipram (0.3-30 mg/kg i.p.) stimulated the accumulation of dopa following inhibition of the aromatic amino acid decarboxylase with 3-hydroxybenzylhydrazine HCl dose-dependently in all brain regions investigated, suggesting that both dopamine and noradrenaline synthesis was enhanced. The stimulatory effect of rolipram on dopa accumulation in dopamine rich regions persisted even after pretreatment with gamma-butyrolactone which by itself increased dopa accumulation three fold. Following inhibition of catecholamine synthesis with alpha-amethyl-p-tyrosine rolipram accelerated the disappearance of noradrenaline and slowed the disappearance of dopamine. At low doses rolipram tended to reduce the pargyline-induced accumulation of 3-methoxytyramine. Rolipram attenuated the accumulation of 5-hydroxytryptophan in the neocortex and the diencephalon of 3-hydroxybenzylhydrazine HCl pretreated rats. The data suggest that rolipram enhances noradrenergic transmission by direct stimulation of tyrosine hydroxylase and by an increase of neuronal activity. Despite a stimulatory effect on tyrosine hydroxylase rolipram does not appear to alter dopamine release and metabolism to a large extent. In view of the occurrence of head-twitches the rolipram-induced reduction of 5-hydroxytryptamine metabolism may be due to feedback inhibition.

Animals↗
PubMed1984

[The combined effects of oxazolam and alcohol on achievement and mood in healthy subjects].

The combined effects of oxazolam (Tranquit), a benzodiazepine, and alcohol were examined in two separate studies. 20 healthy male student subjects participated in study I. 20 mg and 60 mg of oxazolam and placebo were combined with 0.55 g/kg alcohol and alcohol placebo. There were 3-4 subjects in each of the six cells of the 3 X 2 design. 102 healthy male employees of a company participated in study II. 20 mg of oxazolam and placebo were combined with 0.55 g/kg and 0.83 g/kg alcohol and alcohol placebo. There were 17 subjects in each of the six cells of the 2 X 3 design. In both studies achievement tests and subjective tests were applied before and after 90-120 min p.a. An analysis of covariance was used to evaluate the effects (pretest as covariate). The results in both studies showed definite effects of alcohol and only weak drug effects. All effects in the achievement tests pointed in a negative direction. In the few cases where alcohol and drug effects could be shown simultaneously, the effects added up in combination or the drug developed the negative effects of alcohol, which were not demonstrated under placebo alone. For the examined time of measurement the combined effects are comparable to the combined effects of other benzodiazepines.

Adult↗
PubMed1983

[Early bladder function disorders following Wertheim surgery. Causes and therapeutic consequences].

The bladder function of forty five women was studied once before and three times following a Wertheim Operation for Carcinoma of the Cervix. Three quarters of the patients had a diminished bladder capacity two weeks after surgery with an increased bladder filling pressure and a decreased urethral occlusion pressure. After eight and twenty weeks the pre-operative state was almost reached. However there was no complete restoration of the function at that time. Almost all women had a disturbance of the bladder sensitivity. Modern investigations of bladder physiology show that the lax bladder is an expected post-operative neurogenic problem of the vesical plexus. At first this is masked by a hypertonic bladder due to muscle trauma. The postoperative decrease of the urethral occlusion pressure appears to be caused by a partial injury of sympathic nerve fibers. The problem of functional infravesical obstruction is discussed. The treatment is at first accomplished by general perioperative measures. Later on receptor effective drugs are used as necessary following a repeat urodynamic investigation.

Female↗
PubMed1982

Catecholamine metabolism in rat brain following the intracerebroventricular administration of cyclic nucleotides.

The dibutyryl analogues of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were administered into the lateral ventricles and catecholamine metabolites were determined in brain 40 min later. Dibutyryl cAMP elevated the level of homovanillic acid in whole brain and dihydroxyphenyl acetic acid levels in striatum, the dopamine-rich part of the limbic system and hemispheres but neither affected the accumulation of 3-methoxytyramine following inhibition of MAO with pargyline nor dopamine and noradrenaline levels. Normetanephrine accumulating after MAO inhibition was elevated markedly by dibutyryl cAMP. Dibutyryl cGMP was without effect on the catecholamine metabolites investigated. Dibutyryl cAMP appears to stimulate dopamine metabolism within dopaminergic nerve endings but does not stimulate dopamine release. Dibutyryl cAMP-induced activation of noradrenaline metabolism, however, appears to coincide with a stimulation of noradrenaline release.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1979

Catecholamine and 5-hydroxytryptamine synthesis and metabolism following intracerebroventricular injection of dibutyryl cyclic AMP.

Two to seven days after bilateral implantation of polyethylene tubings into the lateral ventricles rats were injected intracerebroventricularly with dibutyryl cAMP or dibutyryl cGMP. The accumulation of dopa and 5-hydroxytryptophan after inhibition of the aromatic amino acid decarboxylase with 3-hydroxybenzylhyrazine HCl, served as a measure of catecholamine and 5-hydroxytryptamine synthesis in vivo. A dose of 100 microgram dibutyryl cAMP per rat but not dibutyryl cGMP increased the accumulation of dopa in all brain regions by 70 to 130%. Both nucleotides stimulated the formation of 5-hydroxytryptophan in the dopamine-rich part of the limbic system and diencephalon and in addition dibutyryl cAMP increased 5-hydroxytryptophan in C. striatum and cerebellum. Dibutyryl cAMP (25-200 microgram per rat) did not change the dopamine levels in the dopamine-rich parts of the brain but decreased the noradrenaline level of the C. striatum in a dose-dependent manner. The same doses of dibutyryl cAMP elevated the 5-hydroxytryptamine level in brain stem and the level of 5-hydroxyindole acetic acid in diencephalon and the limbic system. The disappearance of noradrenaline but not of dopamine after inhibition of catecholamine synthesis with alpha-methyl-p-tyrosine methylester HCl was accelerated in most brain regions. The data are compatible with the view that dibutyryl cAMP stimulates tyrosine and tryptophan hydroxylase directly. In addition, dibutyryl cAMP appears to enhance the utilization of noradrenaline but not that of dopamine. The increased utilization of 5-hydroxytryptamine may be restricted to the diencephalon and the limbic system.

5-Hydroxytryptophan↗