@article{HornBaumannPereiraetal.2012,
  author    = {Horn, Michael and Baumann, Reto and Pereira, Jorge A. and Sidiropoulos, P{\´a}ris N. M. and Somandin, Christian and Welzl, Hans and Stendel, Claudia and L{\"u}hmann, Tessa and Wessig, Carsten and Toyka, Klaus V. and Relvas, Jo{\~a}o B. and Senderek, Jan and Suter, Ueli},
  title     = {Myelin is dependent on the Charcot-Marie-Tooth Type 4H disease culprit protein FRABIN/FGD4 in Schwann cells},
  series = {Brain},
  volume    = {135},
  journal   = {Brain},
  doi       = {10.1093/brain/aws275},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125390},
  pages     = {3567-3583},
  year      = {2012},
  abstract  = {Studying the function and malfunction of genes and proteins associated with inherited forms of peripheral neuropathies has provided multiple clues to our understanding of myelinated nerves in health and disease. Here, we have generated a mouse model for the peripheral neuropathy Charcot-Marie-Tooth disease type 4H by constitutively disrupting the mouse orthologue of the suspected culprit gene FGD4 that encodes the small RhoGTPase Cdc42-guanine nucleotide exchange factor Frabin. Lack of Frabin/Fgd4 causes dysmyelination in mice in early peripheral nerve development, followed by profound myelin abnormalities and demyelination at later stages. At the age of 60 weeks, this was accompanied by electrophysiological deficits. By crossing mice carrying alleles of Frabin/Fgd4 flanked by loxP sequences with animals expressing Cre recombinase in a cell type-specific manner, we show that Schwann cell-autonomous Frabin/Fgd4 function is essential for proper myelination without detectable primary contributions from neurons. Deletion of Frabin/Fgd4 in Schwann cells of fully myelinated nerve fibres revealed that this protein is not only required for correct nerve development but also for accurate myelin maintenance. Moreover, we established that correct activation of Cdc42 is dependent on Frabin/Fgd4 function in healthy peripheral nerves. Genetic disruption of Cdc42 in Schwann cells of adult myelinated nerves resulted in myelin alterations similar to those observed in Frabin/Fgd4-deficient mice, indicating that Cdc42 and the Frabin/Fgd4-Cdc42 axis are critical for myelin homeostasis. In line with known regulatory roles of Cdc42, we found that Frabin/Fgd4 regulates Schwann cell endocytosis, a process that is increasingly recognized as a relevant mechanism in peripheral nerve pathophysiology. Taken together, our results indicate that regulation of Cdc42 by Frabin/Fgd4 in Schwann cells is critical for the structure and function of the peripheral nervous system. In particular, this regulatory link is continuously required in adult fully myelinated nerve fibres. Thus, mechanisms regulated by Frabin/Fgd4-Cdc42 are promising targets that can help to identify additional regulators of myelin development and homeostasis, which may crucially contribute also to malfunctions in different types of peripheral neuropathies.},
  language  = {en}
}
@article{BuchmannBaumannMengetal.2023,
  author    = {Buchmann, J. and Baumann, N. and Meng, K. and Semrau, J. and Kuhl, J. and Pfeifer, K. and Vogel, H. and Faller, H.},
  title     = {Volitional Action Control and Depression in Chronic Pain: Does Action versus State Orientation Moderate the Relations of Pain-Related Cognitions to Depression?},
  series = {Current Psychology},
  volume    = {42},
  journal   = {Current Psychology},
  issn      = {1046-1310},
  doi       = {10.1007/s12144-021-01914-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-308508},
  pages     = {7591-7608},
  year      = {2023},
  abstract  = {In this study, we examined the conditional indirect and direct relations of pain-related cognitions to depression. Subjective helplessness was included as presumably mediating the relations of catastrophizing and thought suppression to depression due to motivational deficits. In addition, moderating effects of dispositional action versus state orientation were analyzed, whereby state orientation indicates volitional deficits in coping with distress. The study was based on self-report data from 536 patients with chronic non-specific low back pain at the beginning of inpatient rehabilitation. Moderated mediation analyses were performed. The indirect catastrophizing- and thought suppression-depression relations were (partially) mediated by subjective helplessness; and moderated by failure-related action versus state orientation. Moreover, action versus state orientation moderated the direct relation of thought suppression to depression. Results suggest that catastrophizing, thought suppression, and subjective helplessness do not lead to depression unless associated with self-regulatory inability (i.e., state orientation). In contrast, action-oriented patients more effectively self-regulate pain-related emotions, disengage from rumination, and distract from pain and thus better avoid the debilitating effects of negative pain-related cognitions on depression. Future research and treatment may more strongly focus on the role of motivational and volitional deficits underlying learned helplessness and depression in chronic pain.},
  language  = {en}
}