Aims: Trypanosomatids have a unique trypanothione-based thiol redox metabolism. The parasite-specific dithiol is synthesized from glutathione and spermidine, with glutathionylspermidine as intermediate catalyzed by trypanothione synthetase. In this study, we address the oxidative stress response of African trypanosomes with special focus on putative protein S-thiolation.Results: Challenging bloodstream Trypanosoma brucei with diamide, H2O2 or hypochlorite results in distinct levels of reversible overall protein S-thiolation. Quantitative proteome analyses reveal 84 proteins oxidized in diamide-stressed parasites. Fourteen of them, including several essential thiol redox proteins and chaperones, are also enriched when glutathione/glutaredoxin serves as a reducing system indicating S-thiolation. In parasites exposed to H2O2, other sets of proteins are modified. Only three proteins are S-thiolated under all stress conditions studied in accordance with a highly specific response. H2O2 causes primarily the formation of free disulfides. In contrast, in diamide-treated cells, glutathione, glutathionylspermidine, and trypanothione are almost completely protein bound. Remarkably, the total level of trypanothione is decreased, whereas those of glutathione and glutathionylspermidine are increased, indicating partial hydrolysis of protein-bound trypanothione. Depletion of trypanothione synthetase exclusively induces protein S-glutathionylation. Total mass analyses of a recombinant peroxidase treated with T(SH)2 and either diamide or hydrogen peroxide verify protein S-trypanothionylation as stable modification.Innovation: Our data reveal for the first time that trypanosomes employ protein S-thiolation when exposed to exogenous and endogenous oxidative stresses and trypanothione, despite its dithiol character, forms protein-mixed disulfides.Conclusion: The stress-specific responses shown here emphasize protein S-trypanothionylation and S-glutathionylation as reversible protection mechanism in these parasites. Antioxid. Redox Signal. 27, 517–533.

The development of a new generation of diagnostic techniques has provided objective data on the physiological function of the spermatozoon. The hemizona assay has been considered the best predictor for in-vitro fertilization results. Its clinical application has been limited to the availability of human oocytes and the use of a special micromanipulator. Here, the sperm binding capacity of hand-sectioned hemizonae was compared with that of oocytes bisected by a micromanipulator. The results obtained in parallel assays showed no statistical differences between the two methods. Therefore, the bisection of oocytes by hand is useful for hemizona assays even in normal clinical laboratories.

ZusammenfassungEine hohe Zahl an Patienten mit psychischen oder psychosomatischen Erkrankungen erhält derzeit keine adäquate fachärztliche bzw. fachpsychotherapeutische Behandlung, sondern verbleibt diesbezüglich alleinig beim Hausarzt. Ursachen sind häufig lange Wartezeiten auf Psychotherapie, patientenseitige Barrieren oder offene differenzialdiagnostische Fragen. Daher entwickelten wir ein Versorgungskonzept, das direkt in der Hausarztpraxis ansetzt und offen für jegliche psychosomatische Störung ist. Dieses Modell, das im Kern eine vor-Ort Sprechstunde durch einen Facharzt für Psychosomatische Medizin umfasst, wird im Folgenden vorgestellt. Erste Erfahrungen bezüglich Inanspruchnahme und Patientenklientel belegen eine hohe Akzeptanz seitens Patienten, Hausärzten und Fachärzten für Psychosomatische Medizin.