Bovine liver slices combined with an androgen transcriptional activation assay: an in-vitro model to study the metabolism and bioactivity of steroids

Previously we described the properties of a rapid and robust yeast androgen bioassay for detection of androgenic anabolic compounds, validated it, and showed its added value for several practical applications. However, biotransformation of potent steroids into inactive metabolites, or vice versa, is not included in this screening assay. Within this context, animal-friendly in-vitro cellular systems resembling species-specific metabolism can be of value. We therefore investigated the metabolic capacity of precision-cut slices of bovine liver using 17β-testosterone (T) as a model compound, because this is an established standard compound for assessing the metabolic capacity of such cellular systems. However, this is the first time that slice metabolism has been combined with bioactivity measurements. Moreover, this study also involves bioactivation of inactive prohormones, for example dehydroepiandrosterone (DHEA) and esters of T, and although medium extracts are normally analyzed by HPLC, here the metabolites formed were identified with more certainty by ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC–TOFMS) with accurate mass measurement. Metabolism of T resulted mainly in the formation of the less potent phase I metabolites 4-androstene-3,17-dione (4-AD), the hydroxy-T metabolites 6α, 6β, 15β, and 16α-OH-T, and the phase II metabolite T-glucuronide. As a consequence the overall androgenic activity, as determined by the yeast androgen bioassay, decreased. In order to address the usefulness of bovine liver slices for activation of inactive steroids, liver slices were exposed to DHEA and two esters of T. This resulted in an increase of androgenic activity, because of the formation of 4-AD and T

Long-term measurements of radon, thoron and their airborne progeny in 25 schools in Republic of Srpska

This article reports results of the first investigations on indoor radon, thoron and their decay products concentration in 25 primary schools of Banja Luka, capital city of Republic Srpska. The measurements have been carried out in the period from May 2011 to April 2012 using 3 types of commercially available nuclear track detectors, named: long-term radon monitor (GAMMA 1)- for radon concentration measurements (CRn); radon-thoron discriminative monitor (RADUET) for thoron concentration measurements (CTn); while equilibrium equivalent radon concentration (EERC) and equilibrium equivalent thoron concentrations (EETC) measured by Direct Radon Progeny Sensors/Direct Thoron Progeny Sensors (DRPS/ DTPS) were exposed in the period November 2011 to April 2012. In each school the detectors were deployed at 10 cm distance from the wall. The obtained geometric mean concentrations were CRn ¼ 99 Bq m�3 and CTn ¼ 51 Bq m�3 for radon and thoron gases respectively. Those for equilibrium equivalent radon concentration (EERC) and equilibrium equivalent thoron concentrations (EETC) were 11.2 Bq m�3 and 0.4 Bq m�3, respectively. The correlation analyses showed weak relation only between CRn and CTn as well as between CTn and EETC. The influence of the school geographical locations and factors linked to buildings characteristic in relation to measured concentrations were tested. The geographical location and floor level significantly influence CRn while CTn depend only from building materials (ANOVA, p � 0.05). The obtained geometric mean values of the equilibrium factors were 0.123 for radon and 0.008 for thoron

Indoor radon, thoron their progeny concentrations in high thoron rural Serbia environments

This article deals with the variation of radon (Rn), thoron (Tn) and their progeny concentrations expressed in terms of equilibrium equivalent concentrations (EERC and EETC), in 40 houses, in four villages of Sokobanja municipality, Southern Serbia. Two types of passive detectors were used: (1) discriminative radon-thoron detector for simultaneous Rn and Tn gases measurements and (2) direct Tn and Rn progeny sensors (DRPS/DTPS) for measuring Rn and Tn progeny concentrations. Detectors were exposed simultaneously for a single period of 12 months. Variations of Tn and EETC appear higher than those of Rn and EERC. Analysis of the spatial variation of the measured concentrations is also reported. This work is part of a wider survey of Rn, Tn and their progeny concentrations in indoor environments throughout the Balkan region started in 2011 year

Assessment of nuclear track detectors exposure in schools of Banja Luka city, Republic of Srpska

Indoor radon, thoron and their decay products concentration measurements were performed in 25 primary schools in Banja Luka city region, the capital of Republic of Srpska. Studies have been carried out in the period from April 2011 to May 2012 using 4 different passive radon (CR39, LR115) and thoron (CR39, LR115) detectors. Detailed statistical analysis of radon and thoron and their progeny concentration distribution considering geological position, type of detector, measuring uncertainty, indoor position of the detectors and building material is given. Elevated levels of radon concentration (>400 Bq m-3) were found only in a few schools