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Biomedical subjects

C Höschl

Publications and source records attributed to C Höschl.

At least 19 recordsLinked to original sources
PubMed2006

Clinical and demographic characteristics of psychiatric patients seropositive for Borrelia burgdorferi.

PURPOSE: Borrelia burgdorferi (Bb) infection can affect the central nervous system and possibly lead to psychiatric disorders. We compared clinical and demographic variables in Bb seropositive and seronegative psychiatric patients and healthy controls. METHOD: Nine hundred and twenty-six consecutive psychiatric patients were screened for antibodies to Bb and compared with 884 simultaneously recruited healthy subjects. RESULTS: Contrary to healthy controls, seropositive psychiatric patients were significantly younger than seronegative ones. None of the studied psychiatric diagnostic categories exhibited stronger association with seropositivity. There were no differences between seropositive and seronegative psychiatric patients in hospitalization length, proportion of previously hospitalized patients and proportion of subjects with family history of psychiatric disorders. CONCLUSION: These findings elaborate on potential association between Bb infection and psychiatric morbidity, but fail to identify any specific clinical 'signature' of Bb infection.

Adult↗
PubMed2005

The influence of low-frequency left prefrontal repetitive transcranial magnetic stimulation on memory for words but not for faces.

Brain imaging studies suggest localization of verbal working memory in the left dorsolateral prefrontal cortex (DLPFC) while face processing and memory is localized in the inferior temporal cortex and other brain areas. The goal of this study was to assess the effect of left DLPFC low-frequency repetitive transcranial magnetic stimulation (rTMS) on verbal recall and face recognition. The study revealed a significant decrease of free recall in word encoding under rTMS (110% of motor threshold, 0.9 Hz) in comparison with sham stimulation (p=0.03), while no significant difference was found with facial memory tests. Our findings support the essential role of the left DLPFC in word but not facial memory and confirm the content specific arrangement of cortical areas involved in semantic memory. As a non-invasive tool, rTMS is useful for cognitive brain mapping and the functional localization of the category specific memory system.

Adult↗
PubMed2005

The effect of tryptophan depletion on brain activation measured by functional magnetic resonance imaging during the Stroop test in healthy subjects.

We investigated the role of serotonin in cognitive activation of the frontal cortex. The serotonergic system was affected by the administration of an amino acids mixture without tryptophan (tryptophan depletion). In a placebo-controlled double-blind cross-over study with 20 healthy volunteers, we tested the hypothesis that a tryptophan (serotonin) decrease affects the activation of prefrontal cortex by the Stroop test. Cognitive brain activation was evaluated by functional magnetic resonance imaging (fMRI). Tryptophan depletion decreased the plasma tryptophan level up to 90 % for five hours after the tryptophan-free drink had been consumed when compared with the same mixture with tryptophan (p?0.0001). Tryptophan depletion did not affect the Stroop test performance. We compared fMRI activation in both conditions (tryptophan depletion and placebo) with plasma tryptophan levels as the covariates. The tryptophan depletion increased the activation (fMRI signal) in the bilateral mediofrontal cortex, anterior cingulate and left dorsolateral prefrontal cortex. The present findings allow the postulate that serotonergic medial forebrain and cingulum bundle pathways play a role in the activity of cortical structures involved in Stroop test processing.

Adult↗
PubMed2004

Alterations in calcium homeostasis as biological marker for mild Alzheimer's disease?

The calcium hypothesis of neurodegenerative disorders such as Alzheimer's disease (AD) suggests that altered cytosolic Ca(2+) levels ( Ca(2+) (i)) and/or disturbances in Ca2+ homeostasis concern cellular mechanisms underlying neuronal pathology. To search for a diagnostic marker of Alzheimer's disease, we measured cytosolic calcium concentrations in platelets of AD patients, age-matched control subjects (AMC), and vascular dementia (VD) patients. The ( Ca(2+) (i)) was determined using long wavelength indicator Fluo-3AM in 21 mild AD patients, 17 AMC, and 23 patients with VD. The basal values of [Ca(2+)](i) were significantly lower in AD compared to AMC. After the addition of 1 mM calcium, the [Ca(2+)](i) markedly increased in platelets of AD compared to AMC and VD. Measurement of calcium homeostasis could provide a very sensitive, but less specific biological marker of AD. These results support the hypothesis that influencing calcium homeostasis may provide a therapeutic strategy in dementia.

Aged↗
PubMed2001

Hippocampal damage mediated by corticosteroids--a neuropsychiatric research challenge.

There is an increasing evidence that corticosteroids damage the hippocampus in rodents and in primates. Hippocampal atrophy induced by corticosteroids may play an important role in the pathogenesis of a range of neuropsychiatric disorders. Hippocampus is necessary for short-term memory consolidation and HPA axis regulation. Signs of hippocampal damage (HPA dysregulation in combination with memory impairment) are found in affective disorders, Alzheimer's disease and in posttraumatic stress disorder. MRI volumetry reveals reduced hippocampal volume in these diseases. Evidence supporting the "glucocorticoid hypothesis" of psychiatric disorders is reviewed in the first part of the paper. Unresolved questions concerning temporary aspects of neurodegeneration, causality, reversibility, type of damage, factors increasing hippocampal vulnerability, and both pharmacological (CRH antagonists, antiglucocorticoid drugs, GABA-ergic, serotonergic, glutamatergic agents) and non-pharmacological (psychotherapy) treatment approaches are discussed in the second part.

Alzheimer Disease↗
PubMed2000

Rights and responsibilities of the psychiatric profession.

Psychiatry as a medical discipline relies on the authority of medicine that is associated with the help to a suffering and deserving individual. If this source of authority is obscured, the discipline will be blamed for serving as a social tool for controlling undesirable phenomena and practices. Psychiatry as a medical science accumulates knowledge on the relationship of biology and psychopathology. It can provide an explanation of the extent to which mental illness participates in socially undesirable behaviour and phenomena. But it cannot explain undesirable social phenomena as a mental illness of sorts, let alone offer an effective treatment for them. We should carefully guard the boundaries of psychiatry to prevent its abuse in the future.

Health Knowledge, Attitudes, Practice↗
PubMed1999

The relationship between central serotonergic activity and insulin sensitivity in healthy volunteers.

In order to determine whether central serotonin (5-HT) activity is related to sensitivity of insulin receptors, 19 healthy volunteers with normal basal glycemia and HbAlc were studied. The relationship between prolactin response to D-fenfluramine (delta PRL) in a challenge test and metabolic clearance rates (MCR) of glucose during the hyperinsulinemic-euglycemic clamp technique was evaluated. delta PRL had been chosen as a correlate of central 5-HT activity. Two levels of insulin concentration of approximately 70 mU/l (MCRsubmax) and 2000 mU/l (MCRmax) were used in a clamp, each for a duration of 120 min. A negative correlation was found between delta PRL and MCRsubmax (r = -0.55, P < 0.02) and between delta PRL and MCRmax (r = -0.51, P < 0.03). We did not find any correlation between the prolactin response to D-fenfluramine and body weight, body mass index (BMI) or waist and hip circumference (WHR). The data support the hypothesis of a close connection between 5-HT activity in the brain and peripheral sensitivity to insulin. The possible physiological mechanisms of this connection are discussed.

Adult↗
PubMed1999

Phosphoinositide signalling system in platelets of schizophrenic patients and the effect of neuroleptic therapy.

Alterations in the phosphoinositide signalling system have been proposed as a possible biological marker of schizophrenia. We studied the levels of inositol 1,4,5-trisphosphate (IP3), cytosolic Ca2+ concentrations ([Ca2+]i), and the incorporation of [32P]-orthophosphate into inositol phospholipids and phosphatidic acid (PA) in blood platelets of neuroleptic-treated schizophrenics in comparison with controls. The [Ca2+]i was significantly higher in platelets of one month neuroleptic-treated patients (155+/-5.8 nM) in comparison with controls (95+/-5.4 nM). Neuroleptic therapy decreased the [Ca2+]i, but even after long-term therapy it remained significantly higher (114+/-5.7 nM) than in controls. Differences were also found in the level of IP3 between controls (30+/-4.0 pmol/10(9) platelets), drug-free schizophrenics (52+/-9.0 pmol/10(9) platelets) and treated patients (50+/-6.0 pmol/10(9) platelets). The increased turnover of PA was observed in platelets of neuroleptic-treated schizophrenic patients. The study suggests that the regulation of calcium homeostasis and pathways involved in the phosphoinositide signalling system are altered in the platelets of schizophrenics. Neuroleptic therapy did not remove the observed changes in [Ca2+]i and IP3 levels.

Adolescent↗
PubMed1997

Predicting academic performance of medical students: the first three years.

OBJECTIVE: The purpose of this exploratory study was to identify a cluster of variables that would most economically explain variations in the grade point averages of medical students during the first 3 years of study. METHOD: Data were derived from a study of 92 students admitted to the 3rd Faculty of Medicine in 1992-1993 academic year and who were still in the medical school at the end of the sixth semester (third year). Stepwise regression analysis was used to build models for predicting log-transformed changes in grade point average after six semesters of study-at the end of the first, second, and third years. Predictor variables were chosen from four domains: 1) high school grade point averages in physics, mathematics, and the Czech language over 4 years of study, 2) results of admission tests in biology, chemistry, and physics, 3) admission committee's assessment of the applicant's ability to reproduce a text, motivation to study medicine, and social maturity, and 4) scores on the sentimentality and attachment scales of the Tridimensional Personality Questionnaire. RESULTS: The regression model, which included performance in high school physics, results of the admission test in physics, assessment of the applicant's motivation to study medicine, and attachment scale score, accounted for 32% of the change in grade point average over six semesters of study. The regression models using the first-, second-, and third-year grade point averages as the dependent variables showed slightly decreasing amounts of explained variance toward the end of the third year of study and within domains, changing the structure of predictor variables. CONCLUSIONS: The results suggest that variables chosen from the assessment domains of high school performance, written entrance examination, admission interview, and personality traits may be significant predictors of academic success during the first 3 years of medical study.

Achievement↗
PubMed1994

[Validity of the Brief Psychiatric Rating Scale].

The internal structure and validity of terms used in the Brief Psychiatric Rating Scale (Overall and Gorham, 1962) was analyzed. The data which had been gained at the entrance examination of 1557 inpatients with the diagnosis according to ICD-9 (schizophrenia simplex, schizophrenia paranoids, schizoaffective disease depressive type, schizoaffective disease manic type, manic-depressive disease manic phase, manic-depressive disease depressive phase) were processed using stepwise discriminant analysis (SDA). Three-dimensional space defined by SDA provided a sufficient frame of relations for the majority of diagnostic groups. Incomplete component analysis justified the assumption of a relatively stabile internal structure of the method. The findings allow to recommend the Czech version of the scale for the purpose of description of psychic impairments in psychiatry.

Adolescent↗
PubMed1993

Predicting therapeutic results with levoprotiline and maprotiline in major depression: the role of the outcome criteria.

We describe a double-blind study involving 58 in-patients with major depression (DSM-III). After one week on placebo, the patients were randomly assigned to either levoprotiline or maprotiline treatment for three weeks. In the next three weeks, responders were maintained on the same medication and non-responders were shifted to treatment with the complementary drug. After the initial three weeks' treatment, 31% of levoprotiline patients and 58% of maprotiline patients had responded. Both in the initial three-week period and after shifting non-responders to the complementary drug, there were significant differences in favour of maprotiline. The comparison of properties of different outcome criteria in prediction analyses shows that the final score gives the best agreement with global evaluation; using the delta score (final minus baseline) or ratio score (final/baseline) as the outcome criterion may yield paradoxical results.

Adult↗
PubMed1993

Prediction: nonsense or hope?

Psychiatry and psychopharmacology are no longer aiming to make a decisive breakthrough at the end of the century. Rather than seeking explanations, research workers are looking for 'predictions'. Three main types of prediction are emerging: a tautological, a heuristic, and an irrelevant one. Few predictions found in the recent literature can be marked as 'logical' ones. Nevertheless, predictions play two important roles: they generate new hypotheses that can be falsified in properly designed scientific experiments; they also may serve to falsify given hypotheses. The main recent findings on predictions in psychiatry are briefly summarised.

Female↗
PubMed1993

Dynamics of the effects of levoprotiline and maprotiline on EEG in patients with major depressive episodes (DSM-III-R).

The presented study compares the effect of the well-tested antidepressant maprotiline and a new antidepressant with an atypical pharmacological profile, levoprotiline, on EEG during repeated assessment after single dose administration. From the original number of 34 patients fulfilling the criteria of a major depressive episode (DSM-III-R) on account of a low-voltage record or pathological findings 11 were eliminated. To 12 of the remaining patients levoprotiline was administered and to 11 maprotiline, after a one-week placebo period, in doses of 150 mg. The EEG was recorded after an accommodation session immediately before, 1.5, 3, 4.5, 6 and 24 hours after a single dose administration. The record was taken on a 16-channel average reference montage at rest with closed eyes. Two-minute intervals were divided into 30 four-second periods at a sampling frequency of 128 Hz. From the signal by means of FFT the spectra were estimated and the mean spectrum for the entire recording was calculated. This was then divided into 10 frequency bands. The new method of frequency analysis of alpha-entropy was also used which is a global measure of the difference between two spectra. Three hours after administration of a single dose levoprotiline had an EEG profile corresponding to the profile of tricyclic antidepressants, i.e. it increased the values of the power spectra density in the region of 5-8.5 Hz and in the entire beta band; the decline of power in the alpha band was, however, absent. As regards maprotiline, 3 hours after administration a profile typical for antidepressants was not found; obviously because of the great variance of values of power spectra density as a result of great interindividual differences in the ingestion phase. Changes of the EEG spectrum expressed as values of alpha-entropy during different periods of apparently assessment are not incidental. After the initial rise of values a decline occurs.

Adult↗
PubMed1992

[Results of a clinical trial of levoprotiline].

The authors submit results of a double blind clinical trial of levoprotiline controlled by maprotiline. In the multicentre study (which is processed and interpreted in stages) participated after written informed consent 58 patients with the diagnosis of a major depressive disorder. During the first three weeks the results of levoprotiline and maprotiline (from 26 patients each) were processed. The trial lasted 42 days. The psychopathology of the patients was evaluated by independent blind raters by means of Montgomery and Asberg's scale (MADRS), Hamilton's scale for depression (HRDS) and general clinical impression (CGI). In all patients also the pharmacological and EEG response was assessed. In comparison to maprotiline, levoprotiline was clinically ineffective. Its plasma levels (40 ng/ml) were one third to one half of the values obtained with maprotiline in the same daily dosage (150 mg). Although levoprotiline has an EEG profile typical for classical thymoleptics, its clinical antidepressive action is negligible.

Adult↗