Biomedical subjects

H Sass

Publications and source records attributed to H Sass.

At least 73 records · Page 4Linked to original sources

PubMed1998

[Experimental detection of inadequate affect regulation in patients with self-mutilating behavior].

According to DSM-IV affective instability in borderline personality disorder is due to marked reactions to environmental events. The aim of this study was to investigate affective responsiveness of abnormal personalities with self-harming impulsive behaviors by means of an affect-stimulation design. The first experiment was based on the presentation of a short story that allowed affective responses to various stimuli to be assessed in regard to quality, intensity, and alterations over time. The second one presented a typical frustration design, which provoked specific feelings of anger and disappointment. Impulsive personalities showed an affective hyperreactivity that was characterized by a decreased threshold for affective responses, as well as by intensive, rapidly changing affects. Furthermore, affect experiences turned out to be qualitatively diffuse and undifferentiated. Results support that affective instability of patients with borderline personality disorder should be differentiated from the autonomous deviations of mood typical of affective disorders. Their affective hyperreactivity is a crucial part of impulsive personality functioning.

Adaptation, Psychological↗

PubMed1998

The ecological niche of the consortium "Pelochromatium roseum"

A dense accumulation of the phototrophic consortium "Pelochromatium roseum" in a small, eutrophic, freshwater lake (Dagowsee, Brandenburg, Germany) was investigated. Within the chemocline, the number of epibionts of the consortia represented up to 19% of the total number of bacteria. Per "P. roseum" a mean value of 20 epibionts was determined. Similar to other aquatic habitats, consortia in the Dagowsee were found only at low light intensities (< 7 &mgr;mol quanta m-2 s-1) and low sulfide concentrations (0-100 &mgr;M). In dialysis cultures of "P. roseum", bacterial cells remained in a stable association only when incubated at light intensities between 5 and 10 &mgr;mol quanta m-2 s-1. Intact consortia from natural samples had a buoyant density of 1046.8 kg m-3, which was much higher than that of ambient chemocline water (995.8 kg m-3). Under environmental conditions and without motility, this density difference would result in rapid sedimentation of consortia toward the lake bottom. Our results indicate that (1) consortia are adapted to a very narrow regime of light intensities and sulfide concentrations, (2) motility and tactic responses must be of ecological significance for the colonization of the free water column of lakes, and (3) phototrophic growth of consortia can be explained only by a cycling of sulfur species in the chemocline, possibly within the consortia themselves.

Journal Article↗

PubMed1998

High genetic and physiological diversity of sulfate-reducing bacteria isolated from an oligotrophic lake sediment.

The community structure of sulfate-reducing bacteria in littoral and profundal sediments of the oligotrophic Lake Stechlin (Germany) was investigated. A collection of 32 strains was isolated from the highest positive dilutions of most-probable-number series, and their partial 16S rRNA gene sequences and genomic fingerprints based on ERIC (enterobacterial repetitive intergenic consensus)-PCR were analyzed. The strains fell into eight distinct phylogenetic lineages, and the majority (70%) showed a close affiliation to the genus Desulfovibrio. Most of the remaining strains (22%) were related to the gram-positive Sporomusa and Desulfotomaculum groups. A high redundancy of 16S rRNA gene sequences was found within several of the phylogenetic lineages. This low phylogenetic diversity was most pronounced for the subset of strains isolated from oxic sediment layers. ERIC-PCR revealed that most of the strains with identical 16S rRNA gene sequences were genetically different. Since strains with identical 16S rRNA gene sequences but different genomic fingerprints also differed considerably with respect to their physiological capabilities, the high diversity detected in the present work is very likely of ecological relevance. Our results indicate that a high diversity of sulfate-reducing bacterial strains can be recovered from the natural environment using the established cultivation media.

DNA Fingerprinting↗

PubMed1998

Cerebral interregional correlations of associative language processing: a positron emission tomography activation study using fluorine-18 fluorodeoxyglucose.

Even though there have been numerous positron emission tomography (PET) activation studies on the perfusional and metabolic bases of language processing, little is known about the intracerebral functional network of language and cognitive processes. It was the aim of this study to investigate the cerebral interregional correlations during voluntary word association versus word repetition in healthy subjects to gain insight into the functional connectivity of associative speech processing. Due to individual variability in functional anatomy, the study protocol was designed as an averaged single-subject study. Eight healthy volunteers performed a verbal association task during fluorine-18 fluorodeoxyglucose (18F-FDG) PET scanning. Two different tasks were performed in randomized order: (a) word repetition (after auditory presentation of nouns) as a control condition, and (b) word association (after auditory presentation of nouns) as a specific semantic activation. The regional metabolic rate of glucose (rMRGlu) was calculated after brain regionalization [112 regions of interest on individual 3D flash magnetic resonance imaging (MRI)] and PET/MRI realignment. Statistical analysis was performed for comparison of association and repetition and for calculation of interregional correlation coefficients during both tasks. Compared with word repetition, word association was associated with significant increases in rMRGlu in the left prefrontal cortex, the left frontal operculum (Broca's area) and the left insula, indicating involvement of these areas in associative language processing. Decreased rMRGlu was found in the left posterior cingulum during word association. During word repetition, highly significant negative correlations were found between the left prefrontal cortex, the contralateral cortex areas and the ipsilateral posterior cingulum. These negative correlations were almost completely eliminated during the association task, suggesting a functional decoupling of the strict intercorrelation pattern.

Adult↗

PubMed1998

Psychrotolerant sulfate-reducing bacteria from an oxic freshwater sediment, description of Desulfovibrio cuneatus sp. nov. and Desulfovibrio litoralis sp. nov.

The most abundant culturable sulfate-reducing bacteria were isolated from the littoral sediment of the oligotrophic Lake Stechlin. The strains STL1 and STL4 were obtained from the oxic uppermost layer, while strain STL6 was isolated from the anoxic zone in 20 to 30 mm depth. The isolates showed a striking morphological feature in tapering off at one end of the cell. Physiological characteristics related them to the genus Desulfovibrio. They contained desulfoviridin. H2, formate, pyruvate, lactate, and fumarate were utilized with sulfate, sulfite, thiosulfate, or elemental sulfur as electron acceptors. All isolates were able to reduce oxygen and survived 120 h of aeration. However, aerobic growth was not observed. The isolates were psychrotolerant, and grew with rates of up to 0.29 d-1 at 4 degrees C. Analysis of the 16S rDNA confirmed that the strains belong to the genus Desulfovibrio. However, they were not closely related to any known member of this genus and formed a new cluster with at least two new species. Strain STL1 and STL4, exhibiting 99.7% sequence similarity in 16S rRNA, are proposed as the new species Desulfovibrio cuneatus sp. nov., while strain STL6 is assigned to the new species Desulfovibrio litoralis sp. nov.

Base Sequence↗

PubMed1998

History, rationale and potential of human experimental hallucinogenic drug research in psychiatry.

Systematic scientific interest in psychedelic substances has a tradition of about 100 years. Numerous human experimental studies have confirmed the existence of a common nucleus of experiences in hallucinogen-induced states and the acute stages of schizophrenic psychoses. However, the degree of resemblance between endogenous and drug-induced psychotic states has been an issue of controversial debate. After the scheduling of psychedelics in the 1960s, human research became highly restricted worldwide and scientific interest in this field faded. The debate about the appropriateness of the psychedelic state as a model for endogenous psychosis therefore seemed to have little practical relevance. Currently there is a revival of scientific interest in human experimental psychedelic research. Consequently, the appropriateness of hallucinogen-induced states as models for psychosis needs to be reappraised. The arguments for and against are summarized in this paper. In conclusion, the drug-induced model psychosis is shown to be a useful model for acute psychotic stages, but not for the nosological entity schizophrenia.

Hallucinogens↗

PubMed1998

Methodological issues of human experimental research with hallucinogens.

Human experimental research with hallucinogenic drugs is potentially able to identify linking variables between the psycho(patho)logical conditions and neurobiological alterations involved in both pharmacologically induced and naturally occurring acute psychotic states. A number of methodological aspects should be considered when planning modern experimental studies with hallucinogenic drugs. The issues of subject selection, repeated measures, and adequate control groups are discussed in this paper. Examples of recent experimental studies are presented which take these aspects into account. The first study examined psychopathological changes, facial expression and semantic priming effects during a psilocybin-induced state. In the second study, semantic priming effects after intake of psilocybin, 3,4-methylenedioxyethylamphetamine (MDE), and d-methamphetamine were investigated. Results confirmed time-dependent effects of psilocybin and the restriction of increased priming effects in the psilocybin group.

Consciousness↗

PubMed1998

Effects of the hallucinogen psilocybin on habituation and prepulse inhibition of the startle reflex in humans.

Schizophrenic patients exhibit deficits in indices of sensorimotor gating, such as habituation and prepulse inhibition (PPI) of the startle reflex. Hallucinogenic drug-induced states are putative models for the early and acute stages of schizophrenic and schizophrenia-spectrum disorders. Hallucinogenic drugs have been shown to disrupt PPI and/or retard habituation of the startle reflex in animal models of schizophrenia, consistent with the view of hallucinogen-induced states as 'model psychoses'. We evaluated the effects of the hallucinogen psilocybin on PPI and habituation of the startle reflex in a double-blind, placebo-controlled human study with 12 healthy subjects. In contrast to animal studies, in our small human sample, psilocybin increased PPI, while having no clear effect on habituation (n = 6). These findings must be considered preliminary because several factors, including dose regimens and experimental parameters, may influence the results of studies on startle plasticity. Further investigations both with psychotic patients in different stages of the disease and with human and animal models of schizophrenia are needed in order to explore the effects of hallucinogens on sensorimotor gating and the relationship between information processing in hallucinogenic drug-induced states and the naturally occurring psychoses.

Adult↗

PubMed1998

Cerebral blood flow velocity in acute schizophrenic patients. A transcranial Doppler ultrasonography study.

BACKGROUND AND PURPOSE: The aim of this study was to determine whether acutely psychotic first-episode schizophrenics show an increased cerebral blood flow velocity and whether this condition is reversible on psychopathological improvement. METHODS: In the first of two examinations, transcranial Doppler ultrasonography and assessment with the Positive and Negative Syndrome Scale (PANSS) were performed on 28 acutely psychotic, neuroleptically naive, first-episode schizophrenics. In the second examination, the same patients were assessed psychometrically (PANSS) as well as with Doppler ultrasonography after psychopathological improvement. RESULTS: Acutely psychotic first-episode schizophrenics showed a significant increase of the mean velocity on both sides in the middle and anterior cerebral arteries and in the right posterior cerebral artery. Blood flow showed significant correlations with productive psychotic symptoms. After psychopathological improvement there was a bilateral normalization of the mean velocity in the middle, anterior, and posterior cerebral arteries. CONCLUSIONS: Acutely psychotic first-episode schizophrenics show a significantly increased bilateral cerebral blood flow velocity, which normalizes on psychopathological improvement. There were significant correlations of cerebral blood flow velocity with psychopathology.

Acute Disease↗

PubMed1998

Special feature: personality and personality disorders. A facet theoretical analysis of the similarity relationships.

Categorical and dimensional models of personality, and personality disorders and their interrelationships, are discussed. A facet theoretical analysis of the structural relationships between personality factors and disorders is described. It is hypothesized that higher-order personality traits organize the personality of both the psychically healthy and the psychically ill, and that personality disorders represent maladaptive variants of traits that are evident in all persons to varying degrees. Data were collected from a clinical (n = 165) and a nonclinical sample (n = 100). Results show that the two classes of variables (personality factors and disorders) have similar relationships to each other, and can be structured in the form of a radex in both samples. Finally, the compatibility of the radex structure with other models is examined, comparing facet theory with factor analytical techniques. The results of the facet theoretical analysis further support the hypothesis of a universal personality model, and a continuous transition from normal personalities to personality disorders.

Adolescent↗

PubMed1998

[Investigations on the effect of "ecstasy" on cerebral glucose metabolism: an 18-FDG PET study].

PURPOSE: The aim of the present study was to determine the acute effects of the "Ecstasy" analogue MDE (3, 4-methylendioxyethamphetamine) on the cerebral glucose metabolism (rMRGlu) of healthy volunteers. METHOD: In a randomised double-blind trial, 16 healthy volunteers without a history of drug abuse were examined with 18-FDG PET 110-120 minutes after oral administration of 2 mg/kg MDE (n = 8) or placebo (n = 8). Beginning two minutes prior to radiotracer injection, a constant cognitive stimulation was maintained for 32 minutes using a word repetition paradigm in order to ensure constant and comparable mental conditions during cerebral 18-FDG uptake. Individual brain anatomy was represented using T1-weighted 3D flash MRI, followed by manual regionalisation into 108 regions-of-interest and PFT/MRI overlay. Absolute quantification of rMRGlu and comparison of glucose metabolism under MDE versus placebo were performed using Mann-Whitney U-test. RESULTS: Absolute global MRGlu was not significantly changed under MDE versus placebo (MDE: 41.8 +/- 11.1 mumol/min/100 g, placebo: 50.1 +/- 18.1 mumol/min/100 g, p = 0.298). The normalised regional metabolic data showed a significantly decreased rMRGlu in the bilateral frontal cortex: left frontal posterior (-7.1%, p < 0.05) and right prefrontal superior (-4.6%, p < 0.05). On the other hand, rMRGlu was significantly increased in the bilateral cerebellum (right: +10.1%, p < 0.05; left +7.6%, p < 0.05) and in the right putamen (+6.2%, p < 0.05). CONCLUSIONS: The present study revealed acute neurometabolic changes under the "Ecstasy" analogon MDE indicating a fronto-striato-cerebellar dysbalance with parallels to other psychotropic substances and various endogenous psychoses respectively.

Administration, Oral↗

PubMed1998

[Quality indicators of patient treatment of schizophrenic patients. Results of a pilot study for external quality assurance using tracer diagnosis].

PURPOSE: In Germany, measures for assuring the quality of inpatient treatment are regulated by legislation. Treatment quality must be presented in comparison with other hospitals. Tracer diagnosis is an established method for external quality assurance in the sphere of somatic medicine. METHOD: To evaluate this method of external quality assurance in psychiatry, the German Society for Psychiatry, Psychotherapy and Nervous Diseases (DGPPN) defined and operationalised quality indicators for the treatment of schizophrenic inpatients. RESULTS: of a multicentre project supported by the German Federal Ministry of Health (BMG) using this inventory in 96 schizophrenic inpatients (ICD-10) from 4 hospitals are presented. The qualification of these indicators of structure, process and outcome while comparing the treatment quality of different hospitals as well as their applicability for internal quality management are discussed.

Adult↗

PubMed1997

Correlation of positive symptoms exclusively to hyperperfusion or hypoperfusion of cerebral cortex in never-treated schizophrenics.

BACKGROUND: Studies of schizophrenia by single photon emission computed tomography (SPECT) and positron emission tomography (PET) have shown both regional cerebral hyperperfusion and hypoperfusion. The aim of this study was to examine the inter-relations between regional cerebral blood flow (rCBF), psychopathology, and effects of neuroleptic therapy. METHODS: 24 never-treated patients with acute schizophrenia were examined with hexamethylpropyleneamine-oxime brain SPECT and assessed psychopathologically according to the positive and negative syndrome scale; they were studied again after neuroleptic treatment and psychopathological remission. rCBF values that deviated from those of 20 controls by more than 2 SD were regarded as abnormal. FINDINGS: Both hyperperfused and hypoperfused patterns were found among schizophrenia patients during acute illness. The seven positive symptoms on the symptom scale showed different correlations with rCBF: formal thought disorders and grandiosity correlated positively (and strongly) with bifrontal and bitemporal rCBF; delusions, hallucinations, and distrust correlated negatively (and strongly) with cingulate, left thalamic, left frontal, and left temporal rCBF. Stereotyped ideas as a negative symptom correlated negatively (and strongly) with left frontal, cingulate, left temporal, and left parietal rCBF. After neuroleptic treatment (and reduction of positive symptoms), only negative symptoms correlated exclusively with bifrontal, bitemporal, cingulate, basal ganglia, and thalamic hypoperfusion. INTERPRETATION: Different positive symptoms are accompanied by different rCBF values--some related to hyperperfusion, others to hypoperfusion. This finding may help to explain observed inconsistencies of perfusion patterns in drug-naïve schizophrenics.

Adult↗

PubMed1997

[Impulsiveness and impulse control. On the psychological and psychopathological conceptualization].

Impulsiveness and impaired impulse control are connected with an increasing number of psychic disorders. While impulsiveness presents an enduring, pervasive predisposition of personality, the DSM-IV category of "impulse control disorder not elsewhere classified" is operationalized by specific dysfunctional behaviors. So far, the construction of impulsiveness has really not been sufficiently clarified. What does it means and how can one describes it. Different means of conceptualization are presented from a psychological and psychopathological point of view. Their critical review leads to the hypothesis that impulsiveness subsumes a specific quality of drive, on the one hand, which is closely related to a person's temperament and control mechanisms on the other. Drive and impulse control represent enduring traits that act on all levels of personality function, including behavior, cognitive processing and affect regulation. Finally, a model of impulsiveness is suggested that reflects the close interactions among drive, affect and cognition in the regulation of behavior.

Disruptive, Impulse Control, and Conduct Disorders↗

PubMed1997

GAL4-responsive UAS-tau as a tool for studying the anatomy and development of the Drosophila central nervous system.

To improve the quality of cytoplasmic labelling of GAL4-expressing cells in Drosophila enhancer-trap and transgenic strains, a new GAL4-responsive reporter UAS-tau, which features a bovine tau cDNA under control of a yeast upstream activation sequence (UAS), was tested. Tau, a microtubule-associated protein, is distributed actively and evenly into all cellular processes. Monoclonal anti-bovine Tau antibody reveals the axonal structure of the labelled cells with detail similar to that of Golgi impregnation. We demonstrate that the UAS-tau system is especially useful for studying processes of differentiation and reorganisation of identified neurones during postembryonic development.

Animals↗

PubMed1997

Affective instability and impulsivity in personality disorder. Results of an experimental study.

Affective instability in borderline personality disorder is due to a marked reactivity to environmental events. The present study focused on the relationship between affective instability and impulsivity in personality disorder. It used an experimental approach in the form of an affect-stimulation design based on the presentation of a short story which allowed for an analysis of affective responses in regard to quality, intensity, and alterations over time. Impulsive personalities showed a strong intensity of affective responses us well as a tendency towards rapid affect alterations supporting the theory of poor affect regulation in subjects with impulsive self-harming behaviour. Results suggest that affective instability is a crucial part of impulsive personality functioning.

Adult↗

PubMed1997

Psychopathological and SPECT findings in never-treated schizophrenia.

A total of 24 never-treated (i.e. drug-naive) actively psychotic schizophrenic patients, operationalized according to DSM-III-R, were examined in a pre-post-treatment design using the Positive and Negative Syndrome Scale for Schizophrenia (PANSS) and 99mTc-HMPAO-single photon emission computed tomography (SPECT) to assess regional cerebral blood flow (rCBF). The control subjects were 20 patients free of neurological and psychiatric symptoms. Before treatment there was only a slight hypofrontality, and hypoperfusion was observed in the left temporal superior region. After treatment, hypofrontality was reduced to one region and temporal hypoperfusion disappeared. Formal thought disorders were accompanied by increased rCBF in the bilateral frontal interior and left temporal superior regions. Delusions were associated with hypoperfusion in the anterior cingulate cortex. Negative symptoms showed no linkage to hypofrontality, either before or after treatment. Factor analysis showed delusions and hallucinations loading on different dimensions. The disorganized dimension correlated positively with all regions of interest, whereas these were negatively correlated with reality distortion.

Adult↗

PubMed1997

Regional cerebral blood flow and negative/positive symptoms in 24 drug-naive schizophrenics.

UNLABELLED: SPECT/PET studies in schizophrenia revealed inconsistent changes of regional cerebral blood flow (rCBF). Frontal hyperperfusion as well as hypoperfusion are described. This study was undertaken to investigate the relations between rCBF, psychopathology according to PANSS and effects of neuroleptic therapy. METHODS: Twenty-four drug-naive acute patients with a first manifestation of schizophrenia were examined with 99mTc-HMPAO brain SPECT and assessed according to PANSS. Of these, 22 were controlled again after neuroleptic treatment. Following attenuation correction, region-to-cerebellar count ratios were obtained from 98 irregular regions of interest drawn in all slices (6.25 mm). The ratios were compared to 20 control subjects, and changes lying outside of 2 s.d. were considered abnormal. RESULTS: In different drug-naive patients, hyperperfusion as well as hypoperfused patterns were found. In drug-naive patients, the seven subscores of positive symptoms (pos 1-7) in PANSS showed different correlations to rCBF: Formal thought disorders (pos 2) and grandiosity (pos 5) were positively correlated to bifrontal and bitemporal rCBF (r = +0.59 to +0.70). Delusional ideas (pos 1), hallucinatory behavior (pos 3) and suspiciousness (pos 6) demonstrated a negative correlation to bifrontal, cingulate, left temporal and left thalamic rCBF (r = -0.59 to -0.66). Stereotyped ideas (neg 7) as a negative symptom showed a negative correlation to left frontal, left temporal and left parietal rCBF (r = -0.59 to -0.65). No correlations were found between residual positive symptoms and rCBF after neuroleptic treatment and clinical improvement, but all negative symptoms (neg 1-7) had a negative correlation to bifrontal, bitemporal, cingulate, basal ganglia and thalamic rCBF (r = -0.59 to -0.74). CONCLUSION: Our results illustrate that different positive symptoms are accompanied by different rCBF values: some induce hyperperfusion, others hypoperfusion. After therapy (and reduction of positive symptoms), only negative symptoms correlate exclusively to hypoperfusion. This may be the crucial factor in explaining inconsistencies of past results in perfusion pattern in drug-naive schizophrenic patients.

Adult↗