Glucocorticoid-induced effects on the growth plate and the IGF system

Glucocorticoids (GCs) are widely used as anti-inflammatory and immunosuppressive drugs. The use of these potent drugs, however, often results in side-effects, such as growth retardation in children. For already many years, this GC-induced growth retardation is suggested to involve impaired action of the components of the growth hormone (GH) - insulin-like growth factor (IGF) system. The components of this system are among the main regulators of postnatal longitudinal bone growth. Longitudinal bone growth is regulated by the growth plates, layers of cartilage (containing cartilage cells, chondrocytes) located at the proximal and distal ends of the long bones. The growth plate is a specialised and organised structure and the chondrocytes in the growth plates follow a tightly controlled program of proliferation and differentiation (resulting in the different zones of the growth plate), which is part of the process of endochondral ossification, resulting in the formation of new bone. This bone formation is responsible for longitudinal bone growth. GC-induced growth retardation involves a mechanism intrinsic to the growth plate. However, not much is known about the molecular mechanism underlying this growth retardation. In my PhD thesis project, I have studied the molecular mechanisms by which GCs bring about their effects on the growth plate, with the main emphasis on the components of the IGF system, using both in vitro and in vivo model systems. We have treated mice with GCs for a short-term (1 week) and a long-term (4 weeks) period. We detected expression of three components of the IGF system in the growth plate: IGF-I, IGF-II and IGFBP-2 (one of the IGF binding proteins). GC treatment only affected IGF-I expression, after 1 week we could show a down-regulation, in contrast, after 4 weeks of treatment we detected an upregulation of IGF-I expression. Besides these changes in gene expression, changes in the proliferation and differentiation of the growth plate chondrocytes were also detected. The initial decrease in IGF-I could contribute to the GC-induced growth retardation, whereas the subsequent increase could be part of a compensatory mechanism to minimise the GC-induced growth retardation at the longer term. We have also studied the effects of GCs on angiogenesis and apoptosis in the growth plate, two essential processes for endochondral ossification to occur. In piglets treated with GCs, apoptosis was increased and blood vessel formation was severely disturbed. The GC treatment down-regulated VEGF expression, which is an important growth factor for angiogenesis. We confirmed the down-regulation of VEGF expression by GCs in primary chondrocyte cultures, derived from neonatal piglets. In these same chondrocyte cultures we have studied the effects of GCs on proliferation and gene expression of the IGF system. In this in vitro model system, GCs down-regulated IGFBP-2 expression, at the transcriptional level (as shown by promoter studies). The obtained data suggest that the IGF system is indeed impaired by GCs at the local level of the growth plate, probably both involving proliferation and differentiation, which is probably part of the molecular mechanism underlying GC-induced growth retardation

Gadolinium contrast agents: dermal deposits and potential effects on epidermal small nerve fibers

Small fiber neuropathy (SFN) affects unmyelinated and thinly myelinated nerve fibers causing neuropathic pain with distal distribution and autonomic symptoms. In idiopathic SFN (iSFN), 30% of the cases, the underlying aetiology remains unknown. Gadolinium (Gd)-based contrast agents (GBCA) are widely used in magnetic resonance imaging (MRI). However, side-effects including musculoskeletal disorders and burning skin sensations were reported. We investigated if dermal Gd deposits are more prevalent in iSFN patients exposed to GBCAs, and if dermal nerve fiber density and clinical parameters are likewise affected. 28 patients (19 females) with confirmed or no GBCA exposure were recruited in three German neuromuscular centers. ISFN was confirmed by clinical, neurophysiological, laboratory and genetic investigations. Six volunteers (two females) served as controls. Distal leg skin biopsies were obtained according to European recommendations. In these samples Gd was quantified by elemental bioimaging and intraepidermal nerve fibers (IENF) density via immunofluorescence analysis. Pain phenotyping was performed in all patients, quantitative sensory testing (QST) only in a subset (15 patients; 54%). All patients reported neuropathic pain, described as burning (n = 17), jabbing (n = 16) and hot (n = 11) and five QST scores were significantly altered. Compared to an equal distribution significantly more patients reported GBCA exposures (82%), while 18% confirmed no exposures. Compared to unexposed patients/controls significantly increased Gd deposits and lower z-scores of the IENF density were confirmed in exposed patients. QST scores and pain characteristics were not affected. This study suggests that GBCA exposure might alter IENF density in iSFN patients. Our results pave the road for further studies investigating the possible role of GBCA in small fiber damage, but more investigations and larger samples are needed to draw firm conclusions

Prospective Risk Assessment of Medicine Shortages in Europe and Israel: Findings and Implications

Introduction: While medicine shortages are complex, their mitigation is more of a challenge. Prospective risk assessment as a means to mitigate possible shortages, has yet to be applied equally across healthcare settings. The aims of this study have been to: 1) gain insight into risk-prevention against possible medicine shortages among healthcare experts; 2) review existing strategies for minimizing patient-health risks through applied risk assessment; and 3) learn from experiences related to application in practice. Methodology: A semi-structured questionnaire focusing on medicine shortages was distributed electronically to members of the European Cooperation in Science and Technology (COST) Action 15105 (28 member countries) and to hospital pharmacists of the European Association of Hospital Pharmacists (EAHP) (including associated healthcare professionals). Their answers were subjected to both qualitative and quantitative analysis (Microsoft Office Excel 2010 and IBM SPSS Statistics®) with descriptive statistics based on the distribution of responses. Their proportional difference was tested by the chi-square test and Fisher's exact test for independence. Differences in the observed ordinal variables were tested by the Mann-Whitney or Kruskal-Wallis test. The qualitative data were tabulated and recombined with the quantitative data to observe, uncover and interpret meanings and patterns. Results: The participants (61.7%) are aware of the use of risk assessment procedures as a coping strategy for medicine shortages, and named the particular risk assessment procedure they are familiar with failure mode and effect analysis (FMEA) (26.4%), root cause analysis (RCA) (23.5%), the healthcare FMEA (HFMEA) (14.7%), and the hazard analysis and critical control point (HACCP) (14.7%). Only 29.4% report risk assessment as integrated into mitigation strategy protocols. Risk assessment is typically conducted within multidisciplinary teams (35.3%). Whereas 14.7% participants were aware of legislation stipulating risk assessment implementation in shortages, 88.2% claimed not to have reported their findings to their respective official institutions. 85.3% consider risk assessment a useful mitigation strategy. Conclusion: The study indicates a lack of systematically organized tools used to prospectively analyze clinical as well as operationalized risk stemming from medicine shortages in healthcare. There is also a lack of legal instruments and sufficient data confirming the necessity and usefulness of risk assessment in mitigating medicine shortages in Europe. © Copyright © 2020 Miljković, Godman, Kovačević, Polidori, Tzimis, Hoppe-Tichy, Saar, Antofie, Horvath, De Rijdt, Vida, Kkolou, Preece, Tubić, Peppard, Martinez, Yubero, Haddad, Rajinac, Zelić, Jenzer, Tartar, Gitler, Jeske, Davidescu, Beraud, Kuruc-Poje, Haag, Fischer, Sviestina, Ljubojević, Markestad, Vujić-Aleksić, Nežić, Crkvenčić, Linnolahti, Ašanin, Duborija-Kovačević, Bochenek, Huys and Miljković

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements