Xenobiotics interfering with corticosteroid action : from adrenal steroid synthesis to peripheral receptor activity

Corticosteroids are steroid hormones synthesized by the adrenal gland and regulating a variety of physiological processes to maintain whole-body homeostasis by acting through their corresponding receptors. Although the adrenal gland is considered one of the most toxin-vulnerable organs and steroid receptor regulation is recognized to have a considerable impact on tissue- and cell-specific steroid signaling, only few studies are currently exploring and characterizing the effects of xenobiotics on corticosteroid hormone action. The first part of this thesis aimed to establish optimized steroid profile analysis in cell culture supernatants and apply it in combination with further biological assessments and molecular modeling for the identification and characterization of exogenous chemicals potentially disrupting corticosteroid hormone production. A widely used in vitro model for studying effects of chemicals on adrenal steroid hormone synthesis constitutes the human H295R adrenocarcinoma cell line. Since the OECD test guideline No. 456 based on H295R cells has several limitations, this thesis refined the H295R steroidogenesis assay by simultaneously analyzing the most important adrenal steroid metabolites using a mass spectrometry-based method. A medium control at the beginning of the experiment as well as reference compounds with known mechanisms were introduced and, additionally, gene expression analyses were performed, in order to not only detect chemical-induced disturbances but also providing initial mechanistic insights into the mode-of-action of a given chemical. The newly established improved version of the H295R steroidogenesis assay was then further evolved by activating the cells either with torcetrapib, a potent inducer of corticosteroid synthesis, or with forskolin, a general inducer of steroidogenesis, allowing to assess the inhibitory potential of various test chemicals. The modified torcetrapib-stimulated H295R assay was then used to evaluate three selected hits from an in silico screening of environmental chemical databases using ligand-based pharmacophore models of 11β-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2). This proof-of-concept for the application of pharmacophore-based virtual screening followed by biological assessment has proven suitable for assessing substances potentially interfering with corticosteroid synthesis. In another study within this thesis, the adapted version of the H295R steroidogenesis assay using forskolin-stimulated cells was applied to investigate the inhibitory effects of 19 anabolic androgenic steroids (AAS) and 3 selective androgen receptor modulators (SARMs). This enabled to group the test compounds according to their individual steroid patterns. Additionally, gene expression analysis, cell-free activity assays and molecular docking calculations contributed to providing initial mechanistic information. Besides direct effects on adrenal steroidogenesis, xenobiotic-induced alterations in circulating steroid hormone levels may arise due to altered feedback regulation or disturbed peripheral steroid metabolism. Thus, in a further part of this thesis drug-induced changes in steroid hormone levels were studied by measuring steroid profiles in human blood and urine samples. In a clinical study, plasma levels of steroid hormones and adrenocorticotropic hormone (ACTH) were analyzed in healthy volunteers administered a single dose of slow-release lisdexamfetamine (100 mg) or immediate-release D-amphetamine (40.3 mg) at equimolar doses. Importantly, lisdexamfetamine and D-amphetamine similarly enhanced the levels of glucocorticoids, androgen precursors and ACTH, suggesting an acute stimulation of the hypothalamic-pituitary-adrenal (HPA) axis. Although lisdexamfetamine showed a delayed time of increase and peak levels of plasma D-amphetamine concentrations compared to the D-amphetamine treatment, drug exposure and drug effects seemed to be comparable between the two formulations. In a clinical case study, a comprehensive analysis of blood and urinary steroid profiles was conducted in samples from two patients receiving posaconazole, an antifungal agent associated with hypertension and hypokalemia due to mineralocorticoid excess. Steroid analyses indicated interindividual differences in the mechanism of mineralocorticoid-based hypertension with preferential CYP11B inhibition in one patient and predominant inhibition of 11β-HSD2 in the second patient. These results show that steroid profiling in plasma and urine samples can not only reveal disturbances of steroid homeostasis but also provide initial mechanistic information. Together, these findings emphasize that molecular modeling combined with biological evaluation represents a valuable approach for the identification and characterization of chemicals potentially interfering with corticosteroid production and to provide initial mechanistic insights. However, in vivo investigations are unavoidable to study the impact of chemicals acting on the HPA axis. Xenobiotics may not only affect steroid hormone production, feedback regulation or pre-receptor control of corticosteroid metabolism, but may also interfere directly with the receptor and steroid signal transduction. In order to understand potential disturbances of glucocorticoid action by xenobiotics, it is important to further clarify the signaling pathways involved in glucocorticoid receptor (GR) activation. Therefore, another part of this thesis focused on the impact of the serine/threonine-specific protein phosphatase PP1α on the activity of the GR. PP1α was found to increase GR activity, and preliminary mechanistic investigations showed that levels of phosphorylated GR-Ser211 were altered and glycogen synthase kinase 3 might be involved. Hence, PP1α appeared to modulate the cellular response to glucocorticoids, implying that impairment of its activity could lead to aberrant glucocorticoid hormone action. In conclusion, these studies identified a novel GR regulating protein that enhances cortisol stimulation by controlling GR phosphorylation. A profound understanding of glucocorticoid signaling might provide the basis for developing cell models and conditions for the detection of chemicals disturbing glucocorticoid sensitivity and thereby contributing to diseases

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): Guidelines for medical 3D printing and appropriateness for clinical scenarios

Este número da revista Cadernos de Estudos Sociais estava em organização quando fomos colhidos pela morte do sociólogo Ernesto Laclau. Seu falecimento em 13 de abril de 2014 surpreendeu a todos, e particularmente ao editor Joanildo Burity, que foi seu orientando de doutorado na University of Essex, Inglaterra, e que recentemente o trouxe à Fundação Joaquim Nabuco para uma palestra, permitindo que muitos pudessem dialogar com um dos grandes intelectuais latinoamericanos contemporâneos. Assim, buscamos fazer uma homenagem ao sociólogo argentino publicando uma entrevista inédita concedida durante a sua passagem pelo Recife, em 2013, encerrando essa revista com uma sessão especial sobre a sua trajetória

The current landscape of European registries for rare endocrine conditions

Objective To identify cross-border international registries for rare endocrine conditions that are led from Europe and to understand the extent of engagement with these registries within a network of reference centres (RCs) for rare endocrine conditions. Methods Database search of international registries and a survey of RCs in the European Reference Network for rare endocrine conditions (Endo-ERN) with an overall response rate of 82%. Results Of the 42 conditions with orphacodes currently covered within Endo-ERN, international registries exist for 32 (76%). Of 27 registries identified in the Orphanet and RD-Connect databases, Endo-ERN RCs were aware of 11 (41%). Of 21 registries identified by the RC, RD-Connect and Orphanet did not have a record of 10 (48%). Of the 29 glucose RCs, the awareness and participation rate in an international registry was highest for rare diabetes at 75 and 56% respectively. Of the 37 sex development RCs, the corresponding rates were highest for disorders of sex development at 70 and 52%. Of the 33 adrenal RCs, the rates were highest for adrenocortical tumours at 68 and 43%. Of the 43 pituitary RCs, the rates were highest for pituitary adenomas at 43 and 29%. Of the 31 genetic tumour RCs, the rates were highest for MEN1 at 26 and 9%. For the remaining conditions, awareness and participation in registries was less than 25%. Conclusion Although there is a need to develop new registries for rare endocrine conditions, there is a more immediate need to improve the awareness and participation in existing registries.This publication is part of the project ‘777215/EuRRECa’ which has received funding from the European Union’s Health Programme (2014–2020)

Radiation Exposure of Patients by Cone Beam CT during Endobronchial Navigation - A Phantom Study

Rationale: Cone Beam Computed Tomography imaging has become increasingly important in many fields of interventional therapies. Objective: Lung navigation study which is an uncommon soft tissue approach. Methods: As no effective organ radiation dose levels were available for this kind of Cone Beam Computed Tomography application we simulated in our DynaCT (Siemens AG, Forchheim, Germany) suite 2 measurements including 3D acquisition and again for 3D acquisition and 4 endobronchial navigation maneuvers under fluoroscopy towards a nodule after the 8th segmentation in the right upper lobe over a total period of 20 minutes (min). These figures reflect the average complexity and time in our experience. We hereby describe the first time the exact protocol of lung navigation by a Cone Beam Computed Tomography approach. Measurement: The hereby first time measured body radiation doses in that approach showed very promising numbers between 0,98-1,15mSv giving specific lung radiation doses of 0,42-0,38 mSv. Main results: These figures are comparable or even better to other lung navigation systems. Cone Beam Computed Tomography offers some unique features for lung interventionists as a realtime 1-step navigation system in an open structure feasible for endobronchial and transcutaneous approach. Conclusions: Due to this low level of radiation exposure Cone Beam Computed Tomography is expected to attract interventionists interested in using and guiding endobronchial or transcutaneous ablative procedures to peripheral endobronchial and other lung lesions

2021 URS Abstract Booklet

Complete Schedule of Events for the 23rd Annual Undergraduate Research Symposium at Minnesota State University, Mankato

Focal Spot, Spring 1993

https://digitalcommons.wustl.edu/focal_spot_archives/1063/thumbnail.jp

Focal Spot, Spring 1998

https://digitalcommons.wustl.edu/focal_spot_archives/1078/thumbnail.jp