Biomedical subjects

M Reuter

Publications and source records attributed to M Reuter.

At least 55 records · Page 3Linked to original sources

PubMed2002

The role of cortisol suppression on craving for and satisfaction from nicotine in high and low impulsive subjects.

The rewarding properties of drug self-administration have been shown to depend on mesolimbic dopamine release but also on the availability of corticosterone, as shown in rats. Since this became particularly evident when tested in rat strains bred for high (HR) and low (LR) reactivity to novel stimuli, the role of cortisol and personality in drug craving was investigated in 60 male nicotine-deprived smokers divided according to questionnaire scores into high and low impulsives, a dimension considered to represent HR/LR rats. They either received the peripheral cortisol blocker metyrapone (MET) or the centrally blocking substance dexamethasone (DEX) or placebo (n=20 each) and were then allowed to smoke. MET more than DEX reduced craving for cigarettes during deprivation. This was only observed in low impulsives while high impulsives developed low craving unmodified by blockade of cortisol. Satisfaction from smoking was less achieved with DEX than with MET and not modified by impulsivity. Differences between MET and DEX in influencing craving during deprivation and satisfaction from smoking were discussed on the basis of different glucocorticoid receptors. The mineralocorticoid receptor (MR) seems to be the 'turn on switch' and the glucocorticoid receptor (GR) the 'turn off switch' in mediating the rewarding properties of dopamine in drug self-administration.

Adult↗

PubMed2002

[Levodopa dependency in Parkinson's disease: case report and review].

Only a few patients with Parkinson's disease and levodopa dependency or abuse have been reported. We present a 35-year-old patient with young-onset Parkinson's disease who developed motor complications, levodopa dependency, and drug-induced psychosis after primary treatment with levodopa. Diagnostic criteria and treatment guidelines for this neuropsychiatric disorder are presented as well as a tentative neurobiological answer to the question of why levodopa dependency is observed only in a minority of patients with Parkinson's disease.

Adult↗

PubMed2002

The nervous and muscular systems in the free-living flatworm Castrella truncata (Rhabdocoela): an immunocytochemical and phalloidin fluorescence study.

In order to broaden the information about the organisation of the nervous system in the Plathelminthes, an immunocytochemical (ICC) study of the free-living flatworm Castrella truncata (Dalyellioida) has been performed. This is the first time a representative of the taxon Rhabdocoela has been studied with the ICC technique. Antibodies to 5-HT and FMRF-amide and confocal scanning laser microscope were used. 5-HT and FMRF-amide immunoreactivity was observed in the neuropile of the brain, in the cerebral neurones, in the three pairs of longitudinal nerve cords and the adjoining neurones, in the pharyngeal nerve ring and in twelve neurones associated with the pharynx. 5-HT and FMRF-amide immunoreactivity occurs in separate sets of neurones. Only FMRF-amide immunoreactivity was observed in a peculiar ellipse-shaped structure in the brain, and in the genital plexus. The type of orthogon is discussed. Staining of the muscular system with TRITC conjugated phalloidin revealed muscle patterns that have not been described previously.

Animals↗

PubMed2002

Neuropeptides in flatworms.

The use of well-characterized antibodies raised to neuronal signal substances and their application through immunocytochemistry and confocal scanning laser microscopy has revolutionized studies of the flatworm nervous system (NS). Data about flatworm neuropeptides and the spatial relationship between neuropeptides and other neuronal signal substances and muscle fibers are presented. Neuropeptides form a large part of the flatworm NS. Neuropeptides are especially important as myoexcitatory transmitters or modulators, controlling the musculature of the attachment organs, the stomatogastric and the reproductive systems.

Acetylcholine↗

PubMed2002

Manipulation of working memory information is impaired in Parkinson's disease and related to working memory capacity.

It has been suggested that in patients with Parkinson's disease (PD), difficulties in the manipulation of information, which result in problems in executive tasks, are related to a reduction of working memory capacity (J. D. E. Gabrieli, J. Singh, G. T. Stebbins, & C. G. Goetz, 1996). The present study selectively varied the manipulation demand irrespective of the maintenance requirement. In a group of 14 PD patients, performance declined overproportionally with the increasing task demand and was significantly correlated with a measure of working memory capacity. These results suggest that the complexity of working memory processing may decisively contribute to the exhaustion of resources in PD patients. Increasing complexity may either affect their manipulation ability directly or impede the management of inhibitory control requirements inherent to the task.

Adult↗

PubMed2002

[High-resolution computed tomography of the lungs in pediatric patients].

Since the introduction of the high-resolution technique more than ten years ago, HRCT has become an established modality for diagnosing diseases of the respiratory system. This is especially true for the diagnosis of lung diseases in adults. Experience in HRCT of the lungs is limited in pediatric patients. This review gives an overview of frequent and less frequent HRCT findings in pulmonary diseases in childhood. A purely reticular pattern is rarely observed in infants. Pulmonary diseases associated with overinflation are relatively frequent. Paired inspiratory-expiratory scans combine morphological analysis with functional information and have improved the diagnosis of air trapping, e. g. in post-infectious bronchiolitis obliterans or bronchopulmonary dysplasia. Especially in children the high radiation exposure is a problem. Even when applying a low-dose protocol the radiation dose of HRCT will still exceed the dose of a chest X-ray by 100 times. The indication for pediatric pulmonary HRCT is limited to selected cases and it should be decided in agreement with the pediatric radiologists and the pediatric pulmonologists.

Adolescent↗

PubMed2002

[Sensitivity of MRI in detecting alveolar Infiltrates: Experimental studies].

PURPOSE: An experimental study using porcine lung explants and a dedicated chest phantom to evaluate the signal intensity of artificial alveolar infiltrates with T 1 - and T 2 -weighted MRI sequences. MATERIAL AND METHODS: 10 porcine lung explants were intubated, transferred into the cavity of a MRI-compatible chest phantom and inflated by continuous evacuation of the artificial pleural space. All lungs were examined with MRI at 1.5 T before and after intra-tracheal instillation of either 100 or 200 ml gelatine-stabilised liquid to simulate alveolar infiltrates. MR-examination comprised gradient echo (2D- and 3D-GRE) and fast spin echo sequences (T 2 -TSE and T 2 -HASTE). The signal intensity of lung parenchyma was evaluated at representative cross sections using a standardised scheme. Control studies were acquired with helical CT. RESULTS: The instilled liquid caused patchy confluent alveolar infiltrates resembling the findings in patients with pneumonia or ARDS. CT revealed typical ground-glass opacities. Before the application of the liquid, only T 2 -HASTE and T 2 -TSE displayed lung parenchyma signals with a signal/noise ratio of 3.62 and 1.39, respectively. After application of the liquid, both T 2 -weighted sequences showed clearly visible infiltrates with an increase in signal intensity of approx. 30 % at 100 ml (p < 0.01) and 60 % at 200 ml (p < 0.01). With 2D- and 3D-GRE the infiltrates were not visible, although the lung parenchyma signal increase was statistically significant. On 2D-GRE the increase in signal intensity reached 0.74 % (p = 0.32) after 100 ml and 5.6 % (p < 0.01) after 200 ml (for 3D-GRE: 2.2 % [p = 0.02] at 100 ml and 4.4 % at 200 ml [p < 0.01]). The CT controls revealed a significant increase of lung density of 17 H.E. at 100 ml (p = 0.02) and 75 H.E. at 200 ml (p < 0.01). CONCLUSIONS: MRI with T 2 -weighted sequences detects artificial alveolar infiltrates with high signal intensity and may be a highly sensitive tool to detect pneumonia in patients.

Animals↗

PubMed2002

[Radiological assessment of small bowel obstructions: Value of conventional enteroclysis and dynamic MR-enteroclysis].

PURPOSE: To compare small bowel lesions, especially stenoses, with conventional enteroclysis, static MRI and dynamic MR-enteroclysis. MATERIALS AND METHODS: Forty-two patients with Crohn's disease or other suspected small bowel lesions were examined. MRI was performed in a static and a dynamic way either within one hour after conventional enteroclysis (n = 30) or a few days afterwards (n = 12). In order to monitor bowel filling and to characterize stenoses in a dynamic fashion, 4 series of coronal T2w HASTE breath hold sequences were used, first without additional bowel opacification and then during administration of 1,5 l methyl cellulose via a naso-intestinal tube in the MR unit. Intravenously applied Buscopan was used to reduce bowel movement. RESULTS: In 4 out of 42 Patients, application of methylcellulose was limited to 1000 ml because of gastrointestinal complaints or visible gastral reflux. All patients could be evaluated. Static MRI performed within one hour after conventional enteroclysis and no additional bowel opacification showed insufficient bowel distension. Distension was still better than in MRI without prior application of contrast medium. On the contrary, dynamic MR - enteroclysis lead to controlled and complete bowel distension which allowed for significantly better evaluation of normal bowel anatomy and pathological alterations of the gut. Because of a better bowel distension and dynamic evaluation, MR-enteroclysis revealed significantly more stenoses (n = 42) than MRI obtained with less distension (n = 27, p < 0.001), and characterization of lesions was comparable to conventional enteroclysis (p < 0.001). Fixed and non-fixed stenoses could be differentiated by dynamic MR-enteroclysis. Furthermore, extraluminal complication of Crohn's disease such as abscesses and fistulae or large bowel manifestation of disease were shown in 13 patients. CONCLUSIONS: Dynamic MR-enteroclysis is feasible in routine diagnostic work-up of the small bowel. It is superior in depicting intra- and extraluminal manifestation of small bowel lesions and enables characterization of stenoses comparable to conventional enteroclysis.

Adolescent↗

PubMed2002

The trigonometric responder approach: a new method for detecting responders to pharmacological or experimental challenges.

The paper presents a newly developed response measure that is particularly suitable for the evaluation of pharmacokinetic data. This method is based on trigonometric considerations, defining a hormone response as the difference between the angle of the slope of the curve before and after drug intake. In addition, the size of this difference is compared to the difference obtained in placebo conditions. In this way, the trigonometric response measure overcomes one of the most problematic shortcomings of the 'area under the curve' (AUC) approach, the problem of the initial value. We will present the mathematical background of the trigonometric method and demonstrate its usefulness by evaluating empirical data (a pharmacological challenge test using the dopamine agonist lisuride) and comparing it to classical AUC measures. This has been achieved by contrasting both approaches with responder definitions according to binary time series analysis and the peak value of the curve.

Algorithms↗

PubMed2002

Addictive and nonaddictive smoking as related to responsivity to neurotransmitter systems.

In a double-blind crossover design on 36 male smokers, differences in hormone responses to a serotonergic (citalopram) and dopaminergic (bromocriptine) challenge were tested, to compare transmitter responsivities in addicted and pleasure-motivated smokers with respective controls. A general score of smoking addiction, according to DSM IV criteria, was associated with a blunted prolactin decrease to bromocriptine, indicating a possible nicotine-induced desensitization of DA receptors. The single questionnaire-based symptom of tolerance was associated with a blunted cortisol response to citalopram, indicating a particular desensitization of serotonin receptors. Nontolerant but addicted subjects exhibited increased serotonergic responsivity, interpreted as resulting from low serotonin levels associated with lack of impulse control. The questionnaire-based score of pleasure-motivated (='indulgent') smoking was associated with high dopaminergic activity (pronounced prolactin responses), confirming findings obtained in subjects exhibiting reward-related personality factors.

Adolescent↗

PubMed2002

Impact of cortisol on emotions under stress and nonstress conditions: a pharmacopsychological approach.

Although the importance of the hypothalamic-pituitary-adrenal axis in emotional stress response is a well-established fact, the causal relationship between glucocorticoids and emotions remains unclear. Therefore, it was tried to elucidate this relationship by an experimental approach in 100 healthy volunteers. The effects of different oral dosages of cortisol (hydrocortisone; 20 and 40 mg) or placebo on emotional states were tested under stress and nonstress conditions in an independent group design. Furthermore, the time of drug application was varied in relation to the onset of the stress/nonstress conditions (1 vs. 2 h prior to exposure). Stress and nonstress conditions were induced by a film depicting violence and neutral scenes, respectively. The results indicate that the application of cortisol ameliorates emotional states irrespective of the time of drug administration and stress exposure. Also the dimensions of activity were increased by cortisol in all experimental conditions, except when applied 1 h before stress onset, indicating an adaptive negative feedback regulation preventing stress-induced overactivation.

Administration, Oral↗

PubMed2001

Energy dependence of particle multiplicities in central Au+Au collisions.

We present the first measurement of the pseudorapidity density of primary charged particles in Au+Au collisions at root square[s(NN)] = 200 GeV. For the 6% most central collisions, we obtain dN(ch)/d(eta)/(/eta/<1) = 650+/-35(syst). Compared to collisions at root square[s(NN)] = 130 GeV, the highest energy studied previously, an increase by a factor of 1.14+/-0.05 at 90% confidence level, is found. The energy dependence of the pseudorapidity density is discussed in comparison with data from proton-induced collisions and theoretical predictions.

Journal Article↗

PubMed2001

Analysis of artefacts and detail resolution of lung MRI with breath-hold T1-weighted gradient-echo and T2-weighted fast spin-echo sequences with respiratory triggering.

The aim of this study was to evaluate feasibility and limitations of two MR sequences for imaging of the lung using a semi-quantitative rating scale. Ten healthy volunteers were assessed with a breath-hold T1-weighted gradient-recalled-echo (TR/TE=129/2.2 ms, matrix 173 x 256) and a T2-weighted turbo spin-echo (TSE) sequence with respiratory triggering (TR/TE=3000-5000/120 ms, matrix 270 x 512) in axial 6-mm slices. The T1-weighted GRE protocol included a pre-saturation pulse over the mediastinal structures. Artefacts and resolution of vessel/airway structures in each lung segment were evaluated by two observers (10 volunteers, 180 segments). Cardiac and vessel pulsation artefacts predominated on T1-weighted GRE, respiration artefacts on T2-weighted TSE (lingula and middle lobe). Pre-saturation of the mediastinum reduced pulsation artefacts on T1-weighted GRE. T1-weighted GRE images were improved by bright flow signal of vessels, whereas image quality of T2-weighted TSE was reduced by black-blood effects in central parts of the lung. Delineation of lung periphery and the mediastinum was superior with T2-weighted TSE. Segmental/sub-segmental vessels (up to fourth/fifth order) and bronchi (up to third order) were identified. All 180 lung segments were imaged in diagnostic quality with at least one of the two sequences (T1-weighted GRE not diagnostic in 9 of 180, T2-weighted TSE in 4 of 180). Both sequences were found to be complementary: superior identification of gross lung anatomy with T1-weighted GRE and higher detail resolution in the periphery and the mediastinum with T2--weighted TSE.

Adult↗

PubMed2001

DNA cleavage by type III restriction-modification enzyme EcoP15I is independent of spacer distance between two head to head oriented recognition sites.

The type III restriction-modification enzyme EcoP15I requires the interaction of two unmethylated, inversely oriented recognition sites 5'-CAGCAG in head to head configuration to allow an efficient DNA cleavage. It has been hypothesized that two convergent DNA-translocating enzyme-substrate complexes interact to form the active cleavage complex and that translocation is driven by ATP hydrolysis. Using a half-automated, fluorescence-based detection method, we investigated how the distance between two inversely oriented recognition sites affects DNA cleavage efficiency. We determined that EcoP15I cleaves DNA efficiently even for two adjacent head to head or tail to tail oriented target sites. Hence, DNA translocation appears not to be required for initiating DNA cleavage in these cases. Furthermore, we report here that EcoP15I is able to cleave single-site substrates. When we analyzed the interaction of EcoP15I with DNA substrates containing adjacent target sites in the presence of non-hydrolyzable ATP analogues, we found that cleavage depended on the hydrolysis of ATP. Moreover, we show that cleavage occurs at only one of the two possible cleavage positions of an interacting pair of target sequences. When EcoP15I bound to a DNA substrate containing one recognition site in the absence of ATP, we observed a 36 nucleotide DNaseI-footprint that is asymmetric on both strands. All of our footprinting experiments showed that the enzyme did not cover the region around the cleavage site. Analyzing a DNA fragment with two head to head oriented recognition sites, EcoP15I protected 27-33 nucleotides around the recognition sequence, including an additional region of 26 bp between both cleavage sites. For all DNA substrates examined, the presence of ATP caused altered footprinting patterns. We assume that the altered patterns are most likely due to a conformational change of the enzyme. Overall, our data further refine the tracking-collision model for type III restriction enzymes.

Adenosine Triphosphate↗

PubMed2001

Charged-particle pseudorapidity density distributions from Au+Au collisions at sqrt[s(NN)]=130 GeV.

The charged-particle pseudorapidity density dN(ch)/d eta has been measured for Au+Au collisions at sqrt[s(NN)] = 130 GeV at RHIC, using the PHOBOS apparatus. The total number of charged particles produced for the 3% most-central Au+Au collisions for /eta/<or=5.4 is found to be 4200+/-470. The evolution of dN(ch)/d eta with centrality is discussed, and compared to model calculations and to data from proton-induced collisions. The data show an enhancement in charged-particle production at midrapidity, while in the fragmentation regions, the results are consistent with expectations from pp and pA scattering.

Journal Article↗

PubMed2001

Ratios of charged antiparticles-to-particles near mid-rapidity in Au + Au collisions at sqrt[s(NN)]=130 GeV.

We have measured the ratios of antiparticles to particles for charged pions, kaons, and protons near mid-rapidity in central Au+Au collisions at sqrt[s(NN)] = 130 GeV. We observe / = 1.00+/-0.01(stat)+/-0.02(syst), / = 0.91+/-0.07(stat)+/-0.06(syst), and / = 0.60+/-0.04(stat)+/-0.06(syst). The / and / ratios give a consistent estimate of the baryo-chemical potential mu(B) of 45 MeV, a factor of 5-6 smaller than in central Pb+Pb collisions at sqrt[s(NN)] = 17.2 GeV.

Journal Article↗

PubMed2001

Comparative study of the spatial relationship between nicotinamide adenine dinucleotide phosphate-diaphorase activity, serotonin immunoreactivity, and GYIRFamide immunoreactivity and the musculature of the adult liver fluke, Fasciola hepatica (Digenea, fasciolidae).

This is the first detailed description of the nitrergic nervous system in a fluke. In this study, the authors analysed the distribution of the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reactivity in neuronal and nonneuronal tissues of the adult fluke Fasciola hepatica and compared this with the distribution of the musculature using tetramethylrhodamine isothiocyanate-phalloidin. To assess the correlation between the number of muscle cells in different parts of the fluke and the NADPH-d-stained cells, the nuclei were stained with Hoechst 333 42, which is specific for chromatin. The spatial relation between the NADPH-d-positive nerves and the 5-hydroxytryptamine (serotonin; 5-HT)-immunoreactive (-IR) and GYIRFamide-IR nervous elements was also examined. The methods complement each other. NADPH-d-positive staining occurs in both in neuronal tissue and nonneuronal tissue. Large, NADPH-d-stained neurones were localised in the nervous system. The oral and ventral suckers are innervated with many large NADPH-d-stained neurones. In addition, the NADPH-d staining reaction follows closely the muscle fibres in both the suckers, in the body, and in the ducts of the reproductive organs. The presence of NADPH-d activity along muscle fibres in F. hepatica and in other flatworms supports a possible myoinhibitory role for nitric oxide. Neuronal nitric oxide synthase in flatworms may form a novel drug target, which would facilitate the development of a novel anthelminthic.

Animals↗

PubMed2001

[Vasculitis--interdisciplinary diagnosis: radiology].

Determination of disease extension and disease activity are in the foreground of diagnostic imaging in vasculitides. There are several radiologic modalities available each having specific indications. Magnetic resonance imaging (MRI) readily depicts granulomas and mucosal inflammations in the paranasal sinuses, nasal cavity and orbits. Computed tomography detects osseous lesions of the skull. Due to its superb sensitivity MRI is an established screening modality for CNS vasculitides, although there are limitations with regard to specificity. In spite of its limited accuracy in most institutions angiography is still required for radiological confirmation of CNS vasculitis. Perfusion and diffusion MR-imaging may combine the advantages of 'conventional' MRI and angiography. By now the method is not fully validated for vasculitides, however. Vascular disease in Takayasu's arteritis and in giant cell arteritis involving predominantly large and medium sized vessels is readily diagnosed by non invasive magnetic resonance angiography. Percutaneous transluminal angioplasty has proven to be an effective and save therapeutic modality for the cure of vascular stenoses and occlusions. Plain film radiography in two planes is the established modality for pulmonary imaging. In pulmonary vasculitides a more thorough analysis of lung disease is provided by high resolution computed tomography. Diagnostic imaging does substantially assist in the interdisciplinary management of patients suffering from vasculitides.

Angioplasty↗