Results of the first national indoor radon survey performed in Serbia.

The first step in every systematic approach to investigating population exposure to radon on a national level is to perform a comprehensive indoor radon survey. Based on general knowledge of the radon levels in Serbia and corresponding doses, the results obtained from a national indoor radon survey would allow policymakers to decide whether it is necessary to establish a national radon programme. For this reason, Serbia initiated work on a national radon action plan (RAP) in 2014 when it was decided to carry out the first national indoor radon survey. The responsibility for establishing the RAP in Serbia is that of the national regulatory body in the field of radiation protection-the Serbian Radiation and Nuclear Safety and Security Directorate (SRBATOM), formerly known as the Serbian Radiation Protection and Nuclear Safety Agency. The first national indoor radon survey was supported by the International Atomic Energy Agency (IAEA) through a Technical Cooperation Programme. Thanks to the IAEA, we received 6000 passive radon devices based on track-etched detectors. In addition, in order to ensure technical support for the project, SRBATOM formed a task force made up of expert radon representatives from national research institutions. This paper presents a thorough description of the sampling design of the first Serbian indoor radon survey. It also presents the results of the national indoor radon survey, including descriptive statistics and testing of the distribution of the obtained results for log-normality. Based on GPS coordinates, indoor radon data were projected onto a map of 10 km × 10 km grid cells. Two values were calculated for each cell to create two distinct maps. One map shows the arithmetic mean value of indoor radon concentration per grid cell, and the other map shows the number of radon detectors per grid cell used for the calculation of mean values.

Liquid Overlay and Collagen-Based Three-Dimensional Models for In Vitro Investigation of Multiple Myeloma.

Multiple myeloma (MM) clones reside in the bone marrow (BM), which plays a role in its survival and development. The interactions between MM and their neighboring mesenchymal stromal cells (MSCs) have been shown to promote MM growth and drug resistance. However, those interactions are often missing or misrepresented in traditional two-dimensional (2D) culture models. Application of novel three-dimensional (3D) models might recapitulate the BM niche more precisely, which will offer new insights into MM progression and survival. Here, we aimed to establish two 3D models, based on MSC spheroids and collagen droplets incorporating both MM cells and MSCs with the goal of replicating the native myeloma context of the BM niche. This approach revealed that although MSCs can spontaneously assemble spheroids with altered metabolic traits, MSC spheroid culture does not support the integration of MM cells. On the contrary, collagen-droplet culture supported the growth of both cell types. In collagen, MSC proliferation was reduced, with the correlating decrease in ATP production and Ki-67 expression, which might resemble in vivo conditions, rather than 2D abundance of nutrients and space. MSCs and MMs were distributed homogenously throughout the collagen droplet, with an apparent CXCL12 expression in MSCs. In addition, the response of MM cells to bortezomib was substantially reduced in collagen, indicating the importance of 3D culture in the investigation of myeloma cell behavior, as drug resistance is one of the most pertinent issues in cancer therapy.

Extracellular Vesicles Derived from Osteogenic-Differentiated Human Bone Marrow-Derived Mesenchymal Cells Rescue Osteogenic Ability of Bone Marrow-Derived Mesenchymal Cells Impaired by Hypoxia.

In orthopedics, musculoskeletal disorders, i.e., non-union of bone fractures or osteoporosis, can have common histories and symptoms related to pathological hypoxic conditions induced by aging, trauma or metabolic disorders. Here, we observed that hypoxic conditions (2% O2) suppressed the osteogenic differentiation of human bone marrow-derived mesenchymal cells (hBMSC) in vitro and simultaneously increased reactive oxygen species (ROS) production. We assumed that cellular origin and cargo of extracellular vesicles (EVs) affect the osteogenic differentiation capacity of hBMSCs cultured under different oxygen pressures. Proteomic analysis revealed that EVs isolated from osteogenic differentiated hBMSC cultured under hypoxia (hypo-osteo EVs) or under normoxia (norm-osteo EVs) contained distinct protein profiles. Extracellular matrix (ECM) components, antioxidants and pro-osteogenic proteins were decreased in hypo-osteo EVs. The proteomic analysis in our previous study revealed that under normoxic culture conditions, pro-osteogenic proteins and ECM components have higher concentrations in norm-osteo EVs than in EVs derived from naïve hBMSCs (norm-naïve EVs). When selected for further analysis, five anti-hypoxic proteins were significantly upregulated (response to hypoxia) in norm-osteo EVs. Three of them are characterized as antioxidant proteins. We performed qRT-PCR to verify the corresponding gene expression levels in the norm-osteo EVs' and norm-naïve EVs' parent cells cultured under normoxia. Moreover, we observed that norm-osteo EVs rescued the osteogenic ability of naïve hBMSCs cultured under hypoxia and reduced hypoxia-induced elevation of ROS production in osteogenic differentiated hBMSCs, presumably by inducing expression of anti-hypoxic/ antioxidant and pro-osteogenic genes.