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263 results on '"BISCHOF, MARTIN"'

12. Ventral striatal hypoactivation is associated with apathy but not diminished expression in patients with schizophrenia

Author

Kirschner, Matthias, Hager, Oliver M., Bischof, Martin, Hartmann, Matthias N., Kluge, Agne, Seifritz, Erich, Tobler, Philippe N., and Kaiser, Stefan

Subjects
Gene expression -- Observations, Schizophrenia -- Genetic aspects, Apathy -- Genetic aspects, Health, Psychology and mental health
Abstract

Background: Negative symptoms of schizophrenia can be grouped in 2 dimensions: apathy and diminished expression. Increasing evidence suggests that negative symptoms are associated with altered neural activity of subcortical and cortical regions in the brain reward system. However, the neurobiological basis of the distinct symptom dimensions within negative symptoms is still poorly understood. The primary aim of our study was to examine the neural correlates of the negative symptom dimensions apathy and diminished expression during a reward processing task. Methods: Patients with schizophrenia and healthy controls underwent event-related fMRI while performing a variant of the Monetary Incentive Delay Task. We assessed negative symptom dimensions using the Brief Negative Symptom Scale. Results: We included 27 patients and 25 controls in our study. Both groups showed neural activation indicated by blood oxygen-level dependent signal in the ventral striatum during reward anticipation. Ventral striatal activation during reward anticipation showed a strong negative correlation with apathy. Importantly, this effect was not driven by cognitive ability, medication, depressive or positive symptoms. In contrast, no significant correlation with the diminished expression dimension was observed. Limitations: Although the results remain significant when controlling for chlorpromazine equivalents, we cannot fully exclude potential confounding effects of medication with atypical antipsychotics. Conclusion: The specific correlation of ventral striatal hypoactivation during reward anticipation with apathy demonstrates a differentiation of apathy and diminished expression on a neurobiological level and provides strong evidence for different pathophysiological mechanisms underlying these 2 negative symptom dimensions. Our findings contribute to a multilevel framework in which apathy and motivational impairment in patients with schizophrenia can be described on psychopathological, behavioural and neural levels., Introduction Negative symptoms are core symptoms of schizophrenia and include avolition, anhedonia, asocialty, blunted affect and alogia. (1,2) They contribute strongly to poor functional outcome and reduced subjective quality of [...]

Published
2016
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21. Plasma obestatin is lower at fasting and not suppressed by insulin in insulin-resistant humans

Author

Anderwald-Stadler, Marietta, Krebs, Michael, Promintzer, Miriam, Mandl, Martina, Bischof, Martin G., Nowotny, Peter, Kastenbauer, Thomas, Luger, Anton, Prager, Rudolf, and Anderwald, Christian

Subjects
Gastrointestinal hormones -- Measurement, Fasting -- Physiological aspects, Insulin resistance -- Physiological aspects, Biological sciences
Abstract

Obestatin, a recently discovered 23-amino acid peptide, is involved in the regulation of appetite and body weight in antagonistic fashion to ghrelin, both deriving from a common precursor peptide. Ghrelin was shown to be associated with insulin resistance, which may also affect obestatin. We investigated the association between insulin resistance and plasma concentrations of obestatin and ghrelin in nondiabetic individuals with high (IS; n = 18, 13 females and 5 males, age 47 [+ or -] 2 yr, BMI = 25.5 [+ or -] 0.9 kg/[m.sup.2]) and low (IR; n = 18, 12 females and 6 males, age 45 [+ or -] 2 yr, P = 0.49, BMI = 27.5 [+ or -] 1.1 kg/[m.sup.2], P = 0.17) insulin-stimulated glucose disposal (M), measured by 2-h hyperinsulinemic (40 mU x [min.sup.-1] x [m.sup.-2]) isoglycemic clamp tests. [M.sub.100-120 min] was higher in IS (10.7 [+ or -] 0.7) than in IR (4.4 [+ or -] 0.2 mg x [min.sup.-l] x [kg.sup.-1], P < [10.sup.-9]), whereas insulin-dependent suppression of free fatty acids (FFA) in plasma was reduced in IR (71 [+ or -] 6% vs. IS: 82 [+ or -] 5%, P < 0.02). In both groups, plasma ghrelin concentrations were comparable at fasting and similarly reduced by 24-28% during insulin infusion. IR had lower fasting plasma obestatin levels (383 [+ or -] 26 pg/ml vs. IS: 469 [+ or -] 23 pg/ml, P < 0.02). Clamp insulin infusion reduced plasma obestatin to ~81% of basal values in IS (P < 0.00002), but not in IR. Fasting plasma obestatin was correlated positively with M (r = 0.34, P = 0.04), HDL cholesterol (r = 0.45, P = 0.01), and plasma ghrelin concentrations (r = 0.80, P < 0.000001) and negatively with measures of adiposity, plasma FFA during clamp (r = -0.42, P < 0.01), and systolic blood pressure (r = -0.33, P < 0.05). In conclusion, fasting plasma concentrations of obestatin, hut not of ghrelin, are reduced in insulin resistance and are positively associated with whole body insulin sensitivity in nondiabetic humans. Furthermore, plasma obestatin is reduced by insulin in insulin-sensitive but not in insulin-resistant persons. ghrelin; hyperinsulinemic clamp test; free fatty acids; appetite regulation

Published
2007

30. Insulin infusion during normoglycemia modulates insulinsecretion according to whole-body insulin sensitivity

Author

Anderwald, Christian, Tura, Andrea, Grassi, Angela, Krebs, Michael, Szendroedi, Julia, Roden, Michael, Bischof, Martin G., Luger, Anton, and Pacini, Giovanni

Subjects
Dextrose -- Physiological aspects -- Health aspects, Insulin -- Physiological aspects -- Health aspects, Glucose -- Physiological aspects -- Health aspects, Type 2 diabetes -- Care and treatment -- Research, Health
Abstract

OBJECTIVE--Glucose is the major stimulus for insulin release. Time course and amount of insulin secreted after glycemic stimulus are different between type 2 diabetes mellitus (T2DM) patients and healthy subjects. [...]

Published
2011
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34. Cross-cultural Validation of the 5-Factor Structure of Negative Symptoms in Schizophrenia

Author

Ahmed, Anthony O, Kirkpatrick, Brian, Galderisi, Silvana, Mucci, Armida, Rossi, Alessandro, Bertolino, Alessandro, Rocca, Paola, Maj, Mario, Kaiser, Stefan, Bischof, Martin, Hartmann-Riemer, Matthias N, Kirschner, Matthias, Schneider, Karoline, et al, University of Zurich, and Ahmed, Anthony O

Subjects
2738 Psychiatry and Mental Health, 10054 Clinic for Psychiatry, Psychotherapy, and Psychosomatics, 610 Medicine & health
Published
2019

35. Inflexible social inference in individuals with subclinical persecutory delusional tendencie

Author

Wellstein, Katharina V, Diaconescu, Andreea Oliviana, Bischof, Martin, Rüesch, Annia, Paolini, Gina, Aponte, Eduardo A, Ullrich, Johannes, Stephan, Klaas Enno, and University of Zurich

Subjects
10093 Institute of Psychology, 10054 Clinic for Psychiatry, Psychotherapy, and Psychosomatics, 10237 Institute of Biomedical Engineering, 150 Psychology
Published
2019

47. S71. CLINICAL, BEHAVIOURAL AND NEURAL VALIDATION OF THE POSITIVE AND NEGATIVE SYMPTOM SCALE (PANSS) AMOTIVATION FACTOR

Author

Philippe N. Tobler, Matthias Kirschner, Bischof Martin, Erich Seifritz, Stefan Kaiser, Mariia Kaliuzhna, Matthias Hartmann, and Fabien Carruzzo

Subjects
Negative symptom, Psychiatry and Mental health, Poster Session I, Scale (ratio), AcademicSubjects/MED00810, Amotivation, Psychology, Clinical psychology
Abstract

Background Negative symptoms of schizophrenia are suggested to map onto two distinct factors – amotivation and diminished expression, which relate to different aspects of behaviour and neural activity. Most research in patients with schizophrenia is conducted with broad symptom assessment scales, such as the PANSS, for which factor solutions allowing the distinction between amotivation and diminished expression have only recently been reported. We aimed to establish whether the PANSS factor structure corresponds to the well-established two-factor structure of the Brief Negative Symptom Scale (BNSS) and whether it allows distinguishing specific behavioural and neuronal correlates of amotivation. Methods In study 1 (N=120) we examined the correlations between the PANSS factors and the BNSS factors. In study 2 (N=31) we examined whether PANSS amotivation is specifically associated with reduced willingness to work for reward in an effort-based decision making task. In study 3 (N=43) we investigated whether PANSS amotivation is specifically correlated with reduced ventral striatal activation during reward anticipation using functional magnetic resonance imaging. Results On the clinical level, the PANSS amotivation and diminished expression were highly correlated with their BNSS counterparts. On the behavioural level, PANSS amotivation factor but not the diminished expression factor was specifically associated with reduced willingness to invest effort to obtain a reward. On the neural level, PANSS amotivation was specifically associated with ventral striatal activation during reward anticipation. Discussion Our data confirm that the two domains of negative symptoms can be measured with the PANSS and are linked to specific aspects of behaviour and brain function. To our knowledge, this is the first study employing behavioural and neural measures to validate a new approach to clinical measurement of negative symptoms. Our results warrant a re-analysis of previous work that used the PANSS to further substantiate the distinction between the two factors in behavioural and neuroimaging studies.

Published
2020

49. Shortening of treatment duration in patients with chronic hepatitis C genotype 2 and 3 - impact of ribavirin dose - a randomized multicentre trial

Author

Bischof Martin, Fischer Gabriele, Laferl Hermann, Scherzer Thomas-Matthias, Metz-Gercek Sigrid, Maieron Andreas, Gschwantler Michael, and Ferenci Peter

Subjects
Hepatitis C, treatment duration, Ribavirin dose, genotype 2 and 3, randomized controlled trial, Medicine, Biology (General), QH301-705.5, Science (General), Q1-390
Abstract

Abstract Background Chronic hepatitis C (CHC) Patients, infected with genotype (GT) 2 or 3 are treated with Peg-IFN and ribavirin (RBV) (800 mg/day) for 24 weeks. Treatment duration can be shortened to 12-16 weeks if a higher dose of RBV (1.000/1.200 mg/day) was used without considerable loss of responsiveness or increased risk of relapse. Previously we have shown that in patients with CHC, GT 2/3 RBV can be reduced to 400 mg/day if administered for 24 weeks without an increase in relapse rates. Therefore we investigated the efficacy of a reduced RBV dosage of 400 mg/day with shorter treatment duration (16 weeks). Methods Treatment naïve patients with CHC, GT 2/3 were randomized to receive 180 μg peginterferonα2a/week in combination with either 800 (group C) or 400 mg/d (group D) for 16 weeks. The primary endpoint was SVR. Results 12 months after the first patient was randomized a inferior outcome of group D as compared to group C was noted, therefore the study was terminated. At study termination 89 patients were enrolled (group C: 31, D: 51). The SVR rate was statistically different in the two study groups with 51.6% in group C and 28.4% in group D (p = 0.038). Patients with low viral load had higher SVR rates (C: 67%, D: 33%) than those with high viral load (C: 33%, D: 21%). Conclusion Both treatment duration and the dose of RBV play a major role to optimize outcome of patients with GT3. If one intends to shorten the treatment weight based RBV dose should be used, if lower RBV doses are used patients should be treated for at least 24 weeks as. A treatment regimen with a reduced RBV dosage and shortened treatment duration is associated with low SVR rates due to high relapse rates. Trial registration NCT01258101

Published
2011
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