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C Fassbender

Publications and source records attributed to C Fassbender.

10 recordsLinked to original sources
PubMed2004

A topography of executive functions and their interactions revealed by functional magnetic resonance imaging.

We used fMRI to study the brain processes involved in the executive control of behavior. The Sustained Attention to Response Task (SART), which allows unpredictable and predictable NOGO events to be contrasted, was imaged using a mixed (block and event-related) fMRI design to examine tonic and phasic processes involved in response inhibition, error detection, conflict monitoring and sustained attention. A network of regions, including right ventral prefrontal cortex (PFC), left dorsolateral PFC (DLPFC) and right inferior parietal cortex, was activated for successful unpredictable inhibitions, while rostral anterior cingulate was implicated in error processing and the pre-SMA in conflict monitoring. Furthermore, the pattern of correlations between left dorsolateral PFC, implicated in task-set maintenance, and the pre-SMA were indicative of a tight coupling between prefrontally mediated control and conflict levels monitored more posteriorly. The results reveal that the executive control of behavior can be separated into distinct functions performed by discrete cortical regions.

Adult↗
PubMed2002

[Rheophoresis. A systematic approach to therapy of age-related macular degeneration (AMD)?].

BACKGROUND: Choroidal microcirculation is impaired in age-related macular degeneration (AMD), and leads to deposition of lipids and proteins in Bruch's membrane. Rheophoresis can improve choroidal microcirculation by eliminating high molecular weight, rheologically relevant plasma proteins. The objective of this post-certification study was to analyse the effect of rheophoresis in 10 AMD patients. PATIENTS AND METHODS: A total of 6 patients with early AMD and 4 with late AMD in one eye (initial visual acuity equivalent 0.2-0.8) received rheophoresis treatment 10 times over an 18-week period. Visual acuity and color vision were determined initially and after 3, 5 and 12 months and fluorescein angiography was performed. RESULTS: Patients with early AMD showed improvement of visual acuity (2 lines on ETDRS charts) in 2 out of 6 cases and a stable visual acuity in 4 out of 6 cases 1 year after rheophoresis, whereas patients with late AMD showed improvement of visual acuity (2 lines on ETDRS charts) in 1 out of 4 cases and a stable visual acuity in 3 out of 4 cases. In red-free fundus photography, a reduction in drusen size and number could be observed in 4 out of 10 cases. CONCLUSION: The results of this investigation seem to be in accordance with data from previously published controlled clinical trials. Recommendations for the indication of rheopheresis for AMD should be further defined and evaluated within the framework base of a multicentric cooperative study.

Aged↗
PubMed2000

Rheopheresis: rheologic, functional, and structural aspects.

Rheopheresis is a specific application of membrane differential filtration, synonymous with double filtration plasmapheresis for extracorporeal hemorheotherapy, eliminating an exactly defined spectrum of high molecular weight proteins from human plasma (e.g.: fibrinogen, alpha-2-macroglobulin, low-density lipoprotein cholesterol, IgM). This results in the improvement of blood flow and microcirculation initiated by lowering blood and plasma viscosity, and erythrocyte aggregation. In this context, microcirculation stands not only for the patency of small blood vessels, but for the complete interactive network between plasma, blood cells, the vessel wall, and cellular and extracellular compartments of the surrounding tissue. Insufficient tissue oxygenation leads to tissue damage, e.g., a microcirculatory disorder develops, creating acute as well as chronic symptoms. Therefore, impaired microcirculation has a rheologic, functional, and structural dimension with respect to involved organs or tissues. Rheopheresis represents a specific therapeutic approach with an acute rheologic as well as chronic functional and structural effects, which was confirmed in pilot and controlled clinical studies for several organ systems. Data from 2 controlled clinical trials are available for the safe and effective treatment in patients with age-related macular degeneration.

Adolescent↗
PubMed1996

Histone H1 suppresses tumor growth of leukemia cells in vitro, ex vivo and in an animal model suggesting extracellular functions of histones.

Purified histone H1 exerts growth inhibition of leukemia cells independent of lineage, stage, and maturation. At 200 micrograms/ml, H1 proved cytotoxic in 19 of 21 of the tested leukemia-derived cell lines and for 11 of 16 of the fresh tumor samples from leukemia patients. In all cases, normal peripheral blood mononuclear cells and bone marrow cells remained unaffected. Multicellular spheroids from the Burkitt's lymphoma cell line IM-9 were growth arrested at 500 micrograms H1/ml. The clonogenic growth of the Burkitt's lymphoma cell line Daudi was arrested at 160 micrograms H1/ml. Synthetic H1-peptides as well as peptides and proteins with biochemical properties similar to H1 had no inhibitory growth effect at equimolar concentrations. Furthermore, 250 micrograms H1 injected into a Burkitt's lymphoma (Daudi), xenotransplanted into nude mice, arrested tumor growth. As shown by electron microscopy and flow cytometry, incubation of leukemia cells with H1 resulted in severe plasma membrane damage and ultimately cytolysis. This report characterizes a 33-kd protein that binds H1 and is responsible for the cell death via destruction of the cell membrane integrity. New extranuclear functions of histones are presented.

Animals↗
PubMed1994

Psychological evaluation of European astronaut applications: results of the 1991 selection campaign.

In the summer of 1991, the European Space Agency (ESA) performed its second selection campaign since 1977 in order to find 10 astronaut candidates (laboratory specialists and space plane specialists). An integral part of this selection process was the psychological evaluation, according to the principles laid down in the study report "Definition of Psychological Testing of Astronaut Candidates." After national preselection, 59 applicants underwent the psychological evaluation, which consisted of the assessment of operational aptitudes (basic cognitive and psychomotor functions) and personality traits (motivation, social capability, stress resistance). The test program included a diverse number of tests, questionnaires, behavioral ratings, biographical data, and semi-structured interviews. About 50 scores were available for each subject. A comparison of the test scores with the original normative data, culture-fairness of the psychological selection, and discriminant functions analyzing the assessment decisions will be presented and discussed.

Adult↗
PubMed1992

Results of the ESA study on psychological selection of astronaut applicants for Columbus Missions I: aptitude testing.

European participation in the Space Station Freedom brought about new challenges for the psychological selection of astronaut candidates, particularly in respect to specific demands of long duration space flights. For this reason existing selection criteria and methods were reassessed. On these grounds a study was undertaken applying a unique composition of aptitude tests to a group of 97 ESA scientists and engineers who are highly comparable to the expected astronaut applicants with respect to age and education. The tests assessed operational aptitudes such as logical reasoning, memory function, perception, spatial orientation, attention, psychomotor function, and multiple task capacity. The study goals were: 1) Verification of psychometric qualities and applicability of tests in a normative group; 2) Search for culture-fair tests by which multi-national groups can be examined; 3) Identification of test methods which consider general and special operational demands of long duration space flights. Based on the empirical findings a test battery was arranged for use in the selection of ESA astronaut applicants. Results showed that 16 out of the 18 employed tests have good psychometric qualities and differentiate reliably in the special group of testees. The meta structure of the test battery as described by a factorial analysis is presented. Applicability of tests was generally high. Tests were culture-fair, however, a relation between English language skills and test results was identified. Since most item material was language-free, this was explained with the importance of English language skills for the understanding of test instructions. Solutions to this effect are suggested.

Adult↗
PubMed1992

Results of the ESA study on psychological selection of astronaut candidates for Columbus Missions II: personality assessment.

A unique composition of personality assessment methods was applied to a group of 97 ESA scientists and engineers. This group is highly comparable to real astronaut candidates with respect to age and education. The list of used tests includes personality questionnaires, problem solving in groups as well as a projective technique. The study goals were: 1. Verification of psychometric qualities and applicability of tests to the target group; 2. Search for culture-fair tests by which multi-national European groups can be examined; 3. Identification of test methods by which the adaptability of the candidates to the psycho-social stress of long-duration space flights can be assessed. Based on the empirical findings, a test battery was defined which can be used in the selection of ESA space personnel.

Adult↗