Biomedical subjects

Petra Arck

Publications and source records attributed to Petra Arck.

3 recordsLinked to original sources

PubMed2006

p75 Neurotrophin Receptor-Mediated Signaling Promotes Human Hair Follicle Regression (Catagen).

Nerve growth factor (NGF) and its apoptosis-promoting low-affinity receptor (p75NTR) regulate murine hair cycling. However, it is unknown whether human hair growth is also controlled through p75NTR, its high-affinity ligand pro-NGF, and/or the growth-promoting high-affinity NGF receptor tyrosine kinase A (TrkA). In microdissected human scalp anagen hair bulbs, mRNA for NGF, pro-NGF, p75NTR, and TrkA was transcribed. Immunohistomorphometry and in situ hybridization detected strong NGF and pro-NGF expression in terminally differentiating inner root sheath keratinocytes, whereas TrkA was co-expressed with p75NTR in basal and suprabasal outer root sheath keratinocytes. During spontaneous catagen development of organ-cultured human anagen hair follicles, p75NTR mRNA levels rose, and p75NTR and pro-NGF immunoreactivity increased dramatically in involuting compartments primarily devoid of TrkA expression. Here, TUNEL(+) apoptotic cells showed prominent p75NTR expression. Joint pro-NGF/NGF administration inhibited hair shaft elongation and accelerated catagen development in culture, which was antagonized by co-administration of p75NTR-blocking antibodies. In addition, mRNA and protein expression of transforming growth factor-beta2 increased early during spontaneous catagen development, and its neutralization blocked pro-NGF/NGF-dependent hair growth inhibition. Our findings suggest that pro-NGF/NGF interacts with transforming growth factor-beta2 and p75NTR to terminate anagen in human hair follicles, implying that p75NTR blockade may alleviate hair growth disorders characterized by excessive catagen development.

Apoptosis↗

PubMed2002

Impact of a relaxation training on psychometric and immunologic parameters in tinnitus sufferers.

OBJECTIVE: Tinnitus often entails severe psychological distress. Reversely, tinnitus may be considered as a chronic stressor. Based on this hypothesis, we investigated whether improving stress-managing capabilities would influence psychological and stress-related immunological parameters in chronic tinnitus sufferers. METHODS: Tinnitus (TPs, n=26) and non-tinnitus participants (NTPs, n=13) took part in a standardised 10-week relaxation program. An additional group of tinnitus sufferers (n=18), randomly assigned to a waiting list, served as control (TC) subjects. Mood, perceived stress, global quality of life, and tinnitus disturbance were assessed before and after the intervention. The stress-sensitive immunological parameters TNF-alpha, IL-6, and IL-10 were measured before, during, and at the end of the intervention. RESULTS: The program resulted in a significantly decreased perception of stress, anxious depression, anger, and tinnitus disturbance, paralleled by a reduction of TNF-alpha. No alterations were noted for IL-6 or IL-10. For the NTPs and TCs, no relevant psychological or immune changes could be observed. CONCLUSION: The data suggest that (1) the training offered improved stress-managing capabilities in chronic tinnitus sufferers, and (2) TNF-alpha may be conceived as a stress marker.

Adult↗

PubMedDate not supplied

The Perceived Stress Questionnaire (PSQ) reconsidered: validation and reference values from different clinical and healthy adult samples.

OBJECTIVE: The aim was to translate, revise, and standardize the Perceived Stress Questionnaire (PSQ) by Levenstein et al. (1993) in German. The instrument assesses subjectively experienced stress independent of a specific and objective occasion. METHODS: Exploratory factor analyses and a revision of the scale content were carried out on a sample of 650 subjects (Psychosomatic Medicine patients, women after delivery, women after miscarriage, and students). Confirmatory analyses and examination of structural stability across subgroups were carried out on a second sample of 1,808 subjects (psychosomatic, tinnitus, inflammatory bowel disease patients, pregnant women, healthy adults) using linear structural equation modeling and multisample analyses. External validation included immunological measures in women who had suffered a miscarriage. RESULTS: Four factors (worries, tension, joy, demands) emerged, with 5 items each, as compared with the 30 items of the original PSQ. The factor structure was confirmed on the second sample. Multisample analyses yielded a fair structural stability across groups. Reliability values were satisfactory. Findings suggest that three scales represent internal stress reactions, whereas the scale "demands" relates to perceived external stressors. Significant and meaningful differences between groups indicate differential validity. A higher degree of certain immunological imbalances after miscarriage (presumably linked to pregnancy loss) was found in those women who had a higher stress score. Sensitivity to change was demonstrated in two different treatment samples. CONCLUSION: We propose the revised PSQ as a valid and economic tool for stress research. The overall score permits comparison with results from earlier studies using the original instrument.

Abortion, Spontaneous↗