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Biomedical subjects

B Andresen

Publications and source records attributed to B Andresen.

At least 37 records · Page 2Linked to original sources
PubMed2000

The activation of phospholipase D by endothelin-1, angiotensin II, and platelet-derived growth factor in vascular smooth muscle A10 cells is mediated by small G proteins of the ADP-ribosylation factor family.

We show here that A10 cells express the phospholipase D (PLD) isoforms PLD1b and PLD2. The activation of PLD in these cells by angiotensin II (AngII), endothelin-1 (ET-1), and platelet-derived growth factor (PDGF) was found to be sensitive to inhibitors of the activation of ADP-ribosylation factor (ARF) but not to blockers of Rho protein function. PDGF, AngII, and ET-1 induced the binding of ARF proteins to cell membranes in a permeabilized cell assay. Cells permeabilized and depleted of ARF were no longer sensitive to stimulation with AngII, ET-1, or PDGF, but the addition of recombinant myristoylated human ARF1 restored agonist-dependent PLD activity. Expression of dominant negative ARF mutants blocked receptor-dependent activation of PLD. PLD activity was also potently stimulated by treatment with phorbol esters, but this activity was only partially inhibited by brefeldin A or by the overexpression of ARF dominant negative mutants. Transient expression of catalytically inactive mutants of PLD2, but not PLD1, inhibited significantly PDGF- and AngII-dependent PLD activity. We conclude: 1) the activation of PLD by cell surface receptors occurs primarily by an ARF-dependent mechanism in A10 cells, whereas the activation of PLD by protein kinase C-dependent pathways is only partially dependent on the regulation of ARF proteins; and 2) cell surface receptors, such as AngII and PDGF, signal primarily via PLD2 in A10 cells.

ADP Ribose Transferases↗
PubMed1999

Topography of the auditory P300 in schizotypal personality.

BACKGROUND: Research with schizophrenic patients has demonstrated reduced amplitude of the P300b elicited with the auditory "oddball" paradigm, as well as reduced P300a amplitude following "novel" stimuli. The focus of the present study was the investigation of these components in a nonclinical sample of participants with high expressions of the schizotypal personality trait. METHODS: By use of an acoustic oddball task, including the presentation of novel stimuli, the event-related brain potentials of 14 participants with "low" and 13 participants with "high" scores on the German adaptation of the "Schizotypal Personality Questionnaire" were investigated. Current source density (CSD) curves and spline-interpolated CSD maps were generated. Peak amplitudes and latencies of the N100, P200, P300a, and P300b were determined for the CSD data. RESULTS: Results indicate no group differences with respect to N100, P200, and P300a amplitudes and latencies. By contrast, the P300b amplitude was significantly smaller in high- as compared to low-scoring participants. Left-temporal as compared to right-temporal P300b was significantly smaller in high- than in low-schizotypal participants. CONCLUSIONS: Confirming results of other researchers, this present study suggests that a reduced P300b amplitude and an altered P300b topography at temporal sites may be a trait-like "marker" of the schizophrenia spectrum.

Adult↗
PubMed1999

Neuroleptic-induced extrapyramidal symptoms are accompanied by cognitive dysfunction in schizophrenia.

Cognitive impairments in schizophrenics have been found to precede tardive dyskinesia and to co-exist with other motor deficits. However, little is yet known about the prevalence of cognitive disturbances in patients with neuroleptic-induced parkinsonism. From the literature on idiopathic parkinson, it was inferred that extrapyramidal symptoms (EPS) are accompanied by cognitive dysfunction. 85 schizophrenic in-patients were divided into EPS high and low scorers according to an established criterion (Simpson Angus Scale, cut-off score: 0.4). Cognitive impairments were assessed using a self-rating instrument measuring disturbances of information processing. Patients with high EPS exhibited significantly elevated scores in six of ten cognitive and perceptual subscales (t = 2.1-3.1) as compared to low EPS patients. It is concluded that high EPS patients suffer from cognitive disturbances which are assumed to possess high relevance for both psycho-social and medical treatment. Cognitive problems may, when not considered, disturb compliance, insight of illness and transfer of learnt skills into everyday life.

Adult↗
PubMed1999

Increased automatic spreading activation in healthy subjects with elevated scores in a scale assessing schizophrenic language disturbances.

BACKGROUND: Previous studies on semantic priming have suggested that schizophrenic patients with language disturbances demonstrate enhanced semantic and indirect semantic priming effects relative to controls. However, the interpretation of semantic priming studies in schizophrenic patients is obscured by methological problems and several artefacts (such as length of illness). We, therefore, used a psychometric high-risk approach to test whether healthy subjects reporting language disturbances resembling those of schizophrenics (as measured by the Frankfurt Complaint Questionnaire subscale 'language') display increased priming effects. In addition, the Schizotypal Personality Questionnaire was used to cover symptoms of schizotypal personality. Enhanced priming was expected to occur under conditions favouring automatic processes. METHODS: One hundred and sixty healthy subjects performed a lexical decision semantic priming task containing two different stimulus onset asynchronicities (200 ms and 700 ms) with two experimental conditions (semantic priming and indirect semantic priming) each. RESULTS: Analyses of variance revealed that the Frankfurt Complaint Questionnaire-' language' high scorers significantly differed from low scorers in three of the four priming conditions indicating increased automatic spreading activation. No significant results were obtained for the Schizotypal Personality Questionnaire total and subscales scores. CONCLUSIONS: In line with Maher and Spitzer it is suggested that increased automatic spreading activation underlies schizophrenia-typical language disturbances which in our study cannot be attributed to confounding variables such as different reaction time baselines, medication or length of illness. Finally, results confirm that the psychometric high-risk approach is an important tool for investigating issues relevant to schizophrenia.

Adult↗
PubMed1999

Adolescent myopathic presentation in two sisters with very long-chain acyl-CoA dehydrogenase deficiency.

Two sisters were investigated at the ages of 20 and 13 years owing to persistently increased serum creatine kinase and recurrent episodes of rhabdomyolysis after emotional stress in the older and myalgias in the younger. The finding of increased levels of cis-5-tetradecenoic acid (C14:1) in plasma, severe hypocarnitinaemia and the absence of a pathological dicarboxylic aciduria in both sisters suggested a very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. Reduced [1-(14)C]palmitate oxidation and deficient mitochondrial VLCAD activity in fibroblasts were found. Mutation analysis revealed compound heterozygosity for Asp365His and Arg410His changes. This late-onset, milder clinical presentation differs from the other two more severe infantile phenotypes described, since there is no hypoglycaemia or cardiac disease. Fatty acid oxidation defects should be investigated in all cases with rhabdomyolysis beginning in adolescence or early adulthood.

Acyl-CoA Dehydrogenase, Long-Chain↗
PubMed1998

Topography of CNV and PINV in schizotypal personality.

The topography of the postimperative negative variation (PINV) was analyzed in participants with high and low scores on the German version of the Schizotypal Personality Questionnaire. Scalp amplitude and Laplacian maps of the terminal contingent negative variation (tCNV) and PINV and the time course of the PINV were compared between the two groups. CNV and PINV were induced with a delayed matching-to-sample task, in which the pattern of the imperative stimulus was either clearly or ambiguous matched to one of the two diamonds simultaneously presented as a warning stimulus 4.0 s earlier. Electroencephalograms were recorded with a DC amplifier (32 channels). Negativity increased from tCNV to PINV, especially at frontal sites, and the PINV was larger under ambiguous than under clear matching conditions. Low-scoring participants showed a right-sided predominance of the PINV, which was absent in high-scoring participants. These results resemble differences in the topography of the PINV between healthy control participants and those with schizophrenia under identical experimental conditions and suggest functional differences between tCNV and PINV.

Adult↗
PubMed1995

[Quantitative EEG, basic disorders and smoking in etiopathogenetically different groups of paranoid-hallucinatory psychoses--an exploratory study].

We performed an exploratory study of quantitative EEG in aetiopathogenetically different paranoid-hallucinatory psychoses divided into the following groups: a) patients with familial psychoses (n = 12), b) patients with neuropsychological deficits (n = 16), c) patients with alcohol and drug abuse (n = 22) and d) patients with so-called sporadic psychoses (n = 12). We found a significant reduction of relative alpha power in the group with neuropsychological deficits. In the group with familial psychosis there was a significant reduction of absolute delta power and a significant increase of relative beta power and dominant beta frequency, especially for the frontal leads. Patients with drug abuse showed a reduction of absolute beta power and an increase of absolute and relative theta power. The group with sporadic psychosis showed a significant slowing of the dominant beta frequency and a significant increase of the absolute power of fast alpha rhythms. The group with sporadic psychoses showed lowered scores for the paranoid-hallucinatory basic symptom factor. The group with neuropsychological deficits showed the most visceral-somatoform basic symptoms, the highest nicotine consumption, increased dyskinesias and more perinatal complications. This group also showed the highest level of neuroleptic and antiparkinson medication. All in all, the group with neuropsychological deficits showed a complex interaction of somatic-exogenic and medical-iatrogenic factors. Furthermore, there was a significant positive correlation between paranoid-hallucinatory basic symptoms and nicotine abuse and high frequency beta waves.

Adult↗
PubMed1993

Blinking, alpha brain waves and smoking in schizophrenia.

Blink rates (BR) and alpha brain waves were studied in 13 schizophrenic and 13 healthy smokers under conditions of smoking deprivation as well as smoking saturation and under different task conditions of smooth pursuit eye movements. Task conditions significantly changed BR and alpha power; smoking enhanced BR and alpha frequency, the latter effect being especially pronounced in schizophrenics for F3-F4 leadings. Concerning BR, groups differed significantly as long as smoking quantity was not statistically controlled. BR, alpha power and smoking quantity were consistently correlated above chance levels. Results are discussed with respect to the blink alpha neurocircuit model.

Adult↗
PubMed1991

Specific diagnosis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency in dried blood spots by a polymerase chain reaction (PCR) assay detecting a point-mutation (G985) in the MCAD gene.

The discovery of a point-mutation, adenine-to-guanine, at position 985 in the gene coding for MCAD (G985), gave the basis for an easy and specific polymerase chain reaction test. We tested the specificity of such a PCR based assay and detected correctly G985 and A985 in sequence verified cDNA clones. We showed that the G985 mutation is present in genomic DNA from 48 of 50 patients with confirmed MCAD deficiency, originating from various European countries, Australia and the USA. On the basis of this high frequency of the G985 mutation among patients, we improved and optimized the assay with respect to reliability and convenience for routine diagnostic and screening purposes. As little as 2 microliters blood from filter-paper blood-spots (Guthrie spots) is sufficient for the test.

Acyl-CoA Dehydrogenase↗