Consideration of the bioavailability of metal/metalloid species in freshwaters: experiences regarding the implementation of biotic ligand model-based approaches in risk assessment frameworks

After the scientific development of Biotic Ligand Models (BLMs) in recent decades these models are now considered suitable for implementation in regulatory risk assessment of metals in freshwater bodies. The approach has been developed over several years and has been described in many peer-reviewed publications. The original complex BLMs have been applied in prospective risk assessment reports for metals and metal compounds and are also recommended as suitable concepts for the evaluation of monitoring data in the context of the European Water Framework Directive. Currently, several user-friendly BLM-based bioavailability software tools are available for assessing the aquatic toxicity of a limited number of metals (mainly copper, nickel, and zinc). These tools need only a basic set of water parameters as input (e.g., pH, hardness, dissolved organic matter and dissolved metal concentration). Such tools seem appropriate to foster the implementation in routine water quality assessments. This work aims to review the existing bioavailability-based regulatory approaches and the application of available BLM-based bioavailability tools for this purpose. Advantages and possible drawbacks of these tools (e.g., feasibility, boundaries of validity) are discussed, and recommendations for further implementation are given

Item response theory analysis of cognitive tests in people with dementia:a systematic review

BACKGROUND: Performance on psychometric tests is key to diagnosis and monitoring treatment of dementia. Results are often reported as a total score, but there is additional information in individual items of tests which vary in their difficulty and discriminatory value. Item difficulty refers to an ability level at which the probability of responding correctly is 50%. Discrimination is an index of how well an item can differentiate between patients of varying levels of severity. Item response theory (IRT) analysis can use this information to examine and refine measures of cognitive functioning. This systematic review aimed to identify all published literature which had applied IRT to instruments assessing global cognitive function in people with dementia. METHODS: A systematic review was carried out across Medline, Embase, PsychInfo and CINHAL articles. Search terms relating to IRT and dementia were combined to find all IRT analyses of global functioning scales of dementia. RESULTS: Of 384 articles identified four studies met inclusion criteria including a total of 2,920 people with dementia from six centers in two countries. These studies used three cognitive tests (MMSE, ADAS-Cog, BIMCT) and three IRT methods (Item Characteristic Curve analysis, Samejima’s graded response model, the 2-Parameter Model). Memory items were most difficult. Naming the date in the MMSE and memory items, specifically word recall, of the ADAS-cog were most discriminatory. CONCLUSIONS: Four published studies were identified which used IRT on global cognitive tests in people with dementia. This technique increased the interpretative power of the cognitive scales, and could be used to provide clinicians with key items from a larger test battery which would have high predictive value. There is need for further studies using IRT in a wider range of tests involving people with dementia of different etiology and severity

Levels Of 12 Perfluorinated Chemicals In Pooled Australian Serum, Collected 2002-2003, In Relation To Age, Gender, And Region

Pooled serum samples from 3802 Australian residents were analyzed for four perfluoroalkylsulfonates, seven perfluoroalkylcarboxylates, and perfluorooctanesulfonamide (PFOSA). Serum was collected from men and women of five different age groups and from rural and urban regions in Australia. The highest mean concentration was obtained for perfluorooctane sulfonate (PFOS, 20.8 ng/mL) followed by perfluorooctanoic acid (PFOA, 7.6 ng/mL), perfluorohexane sulfonate (PFHxS, 6.2 ng/mL), perfluorononanoic acid (PFNA, 1.1 ng/mL), and PFOSA (0.71 ng/mL). Additional four PFCs were detected in 5-18 % of the samples at concentrations near the detection limits (0.1-0.5 ng/mL). An increase in PFOS concentration with increasing age in both regions and genders was observed. The male pool levels of some of the age groups compared to females were higher for PFOS, PFOA, and PFHxS. In contrast, PFNA concentrations were higher in the female pools. No substantial difference was found in levels of PFCs between the urban and rural regions. The levels are equal or higher than previously reported serum levels in Europe and Asia but lower compared to the U. S. A. These results suggest that emissions from production in the Northern Hemisphere are of less importance for human exposure

Initial Characterization of the Hemolysin Stachylysin from Stachybotrys chartarum

Stachybotrys chartarum is a toxigenic fungus that has been associated with human health concerns, including pulmonary hemorrhage and hemosiderosis. This fungus produces a hemolysin, stachylysin, which in its apparent monomeric form has a molecular mass of 11,920 Da as determined by matrix-assisted laser desorption ionization–time of flight mass spectrometry. However, it appears to form polydispersed aggregates, which confounds understanding of the actual hemolytically active form. Exhaustive dialysis or heat treatment at 60°C for 30 min inactivated stachylysin. Stachylysin is composed of about 40% nonpolar amino acids and contains two cysteine residues. Purified stachylysin required more than 6 h to begin lysing sheep erythrocytes, but by 48 h, lysis was complete. Stachylysin also formed pores in sheep erythrocyte membranes

Multivariate methods for the comparison of factor structures in cross-cultural research - An illustration with the big five questionnaire

The goal of the present study was to demonstrate the value of a multiple data analytic approach for testing the cross-cultural generalizability of a personality measure. Data were collected in four different countries (Italy, Germany, Spain, and the United States) on the Big Five Questionnaire (BFQ), which is a measure of the Five Factor Model of personality traits. Different analytical strategies were conducted. Item-level analyses were carried out to study item bias and to select (by means of simultaneous component analysis) the BFQ items that showed better functioning in all countries simultaneously. Scale-level analyses were conducted on item aggregates and were focused on the examination of structural or construct equivalence (i.e., comparability of latent structures). Three analytic approaches were compared (exploratory factor analysis, simultaneous component analysis, and confirmatory factor analysis), and converged in corroborating the basic five factor structure across the four country samples. However, these methods also yielded some noteworthy differences in the conclusions that could be drawn from the analyses. Both the methodological and conceptual implications of this multiple analytic approach are discussed