University of Marburg

About: University of Marburg is a education organization based out in Marburg, Germany. It is known for research contribution in the topics: Population & Gene. The organization has 23195 authors who have published 42907 publications receiving 1506069 citations. The organization is also known as: Philipps University of Marburg & Philipps-Universität.

Effects of reminiscence interventions on psychosocial outcomes: a meta-analysis.

Abstract: Objectives: This study integrated results from controlled trials of reminiscence interventions. Methods: Meta-analysis was used to aggregate results from 128 studies on 9 outcome variables. Results: Compared to non-specific changes in control-group members, moderate improvements were observed at posttest with regard to ego-integrity (g = 0.64) and depression (g = 0.57 standard deviation units). Small effects were found on purpose in life (g = 0.48), death preparation (g = 0.40), mastery (g = 0.40), mental health symptoms (g = 0.33), positive well-being (g = 0.33), social integration (g = 0.31), and cognitive performance (g = 0.24). Most effects were maintained at follow-up. We observed larger improvements of depressive symptoms in depressed individuals (g = 1.09) and persons with chronic physical disease (g = 0.94) than in other individuals, and in those receiving life-review therapy (g = 1.28) rather than life-review or simple reminiscence. Moderating effects of the control condition were also detected. ...

Affective mediators of intergroup contact: a three-wave longitudinal study in South Africa

Abstract: Intergroup contact (especially cross-group friendship) is firmly established as a powerful strategy for combating group-based prejudice (Pettigrew & Tropp, 2006). Great advances have been made in understanding how contact reduces prejudice (Brown & Hewstone, 2005), highlighting the importance of affective mediators (Pettigrew & Tropp, 2008). The present study, a 3-wave longitudinal study undertaken among minority-status Colored high school children in South Africa (N = 465), explored the full mediation of the effects of cross-group friendships on positive outgroup attitudes, perceived outgroup variability, and negative action tendencies via positive (affective empathy) and negative (intergroup anxiety) affective mediators simultaneously. The target group was the majority-status White South African outgroup. As predicted, a bidirectional model described the relationship between contact, mediators, and prejudice significantly better over time than either autoregressive or unidirectional longitudinal models. However, full longitudinal mediation was only found in the direction from Time 1 contact to Time 3 prejudice (via Time 2 mediators), supporting the underlying tenet of the contact hypothesis. Specifically, cross-group friendships were positively associated with positive outgroup attitudes (via affective empathy) and perceived outgroup variability (via intergroup anxiety and affective empathy) and were negatively associated with negative action tendencies (via affective empathy). Following Pettigrew and Tropp (2008), we compared two alternative hypotheses regarding the relationship between intergroup anxiety and affective empathy over time. Time 1 intergroup anxiety was indirectly negatively associated with Time 3 affective empathy, via Time 2 cross-group friendships. We discuss the theoretical and empirical contributions of this study and make suggestions for future research.

The tyrocidine biosynthesis operon of Bacillus brevis: complete nucleotide sequence and biochemical characterization of functional internal adenylation domains.

Abstract: The cyclic decapeptide antibiotic tyrocidine is produced by Bacillus brevis ATCC 8185 on an enzyme complex comprising three peptide synthetases, TycA, TycB, and TycC (tyrocidine synthetases 1, 2, and 3), via the nonribosomal pathway. However, previous molecular characterization of the tyrocidine synthetase-encoding operon was restricted to tycA, the gene that encodes the first one-module-bearing peptide synthetase. Here, we report the cloning and sequencing of the entire tyrocidine biosynthesis operon (39.5 kb) containing the tycA, tycB, and tycC genes. As deduced from the sequence data, TycB (404,562 Da) consists of three modules, including an epimerization domain, whereas TycC (723,577 Da) is composed of six modules and harbors a putative thioesterase domain at its C-terminal end. Each module incorporates one amino acid into the peptide product and can be further subdivided into domains responsible for substrate adenylation, thiolation, condensation, and epimerization (optional). We defined, cloned, and expressed in Escherichia coli five internal adenylation domains of TycB and TycC. Soluble His6-tagged proteins, ranging from 536 to 559 amino acids, were affinity purified and found to be active by amino acid-dependent ATP-PPi exchange assay. The detected amino acid specificities of the investigated domains manifested the colinear arrangement of the peptide product with the respective module in the corresponding peptide synthetases and explain the production of the four known naturally occurring tyrocidine variants. The Km values of the investigated adenylation domains for their amino acid substrates were found to be comparable to those published for undissected wild-type enzymes. These findings strongly support the functional integrities of single domains within multifunctional peptide synthetases. Directly downstream of the 3' end of the tycC gene, and probably transcribed in the tyrocidine operon, two tandem ABC transporters, which may be involved in conferring resistance against tyrocidine, and a putative thioesterase were found.

Asymmetric hydrogenation of aromatic compounds

Abstract: The asymmetric hydrogenation of aromatic and heteroaromatic compounds arguably presents one of the most attractive methods for the synthesis of six-membered cyclic compounds. In recent years, a number of promising stereoselective methods for the asymmetric hydrogenation of pyridines and related heterocycles have been reported.