Method evaluation study of a new generation of vitamin D assays     

Dietmar Enko  Gernot Kriegsh?user  Robert Stolba  Elfriede Worf  Gabriele Halwachs-Baumann 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2015,25(2):203-212

Introduction

Recently several diagnostic manufacturers have launched new 25-hydroxy-vitamin D (25[OH]D) assays, which are aligned to the National Institute of Standards and Technology (NIST) Standard Reference Materials (SRM) (NIST, Gaithersburg, Maryland). The aim of this study was to compare the performance of one liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, one enzyme linked immunosorbent assay (ELISA), and one recalibrated and previous version of a chemiluminescence immunoassay (CLIA).

Material and methods

Serum-aliquots of 198 patient samples from routine 25(OH)D analysis were measured by the ClinMass® LC-MS/MS Complete Kit (RECIPE Chemicals + Instruments GmbH, Munich, Germany), the ORGENTEC 25(OH)D₃/D₂ ELISA (ORGENTEC Diagnostika GmbH, Mainz, Germany), the recalibrated Immunodiagnostic Systems (IDS)-iSYS 25(OH)D^S and the previous used IDS-iSYS 25(OH)D CLIA (Immunodiagnostic Systems Ltd, Boldon, United Kingdom). Bland-Altman and Deming regression analyses were calculated for methods comparison of all tested 25(OH)D assays. The LC-MS/MS method was defined as the reference method. Within-run and between-run precision measurements were performed for all methods with three different concentration levels.

Results

Compared to the LC-MS/MS method, the new IDS-iSYS 25(OH)D^S and ORGENTEC 25(OH)D₃/D₂ assay demonstrated mean relative biases of 16.3% and 17.8%. The IDS-iSYS 25(OH)D assay showed the lowest mean bias of 1.5%. Deming regression analyses of the recalibrated IDS-iSYS 25(OH)D^S and the ORGENTEC 25(OH)D₃/D₂ assay showed proportional differences, when compared to the reference method. All assays showed a within-run and between-run imprecision of ≤ 20% at each of the evaluated concentration levels.

Conclusions

The evaluated standardized immunoassays and LC-MS/MS are useful methods for measuring 25(OH)D serum-levels in clinical laboratories.Key words: vitamin D, immunoassays, liquid chromatography-tandem mass spectrometry, reference standards, quality improvement  相似文献   

Creativity in students’ modelling competencies: conceptualisation and measurement     

Lu  Xiaoli  Kaiser  Gabriele 《Educational Studies in Mathematics》2022,109(2):287-311

Educational Studies in Mathematics - Modelling competencies are currently included in numerous curricula worldwide and are generally accepted as a complex, process-oriented construct. Therefore,...  相似文献   

Expert and preservice secondary teachers’ competencies for noticing student thinking about modelling     

Cai  Jinfa  LaRochelle  Raymond  Hwang  Stephen  Kaiser  Gabriele 《Educational Studies in Mathematics》2022,109(2):431-453

Educational Studies in Mathematics - This study examined how expert and novice (preservice) teachers solved mathematical modelling tasks as well as how they noticed written artifacts of student...  相似文献   

Development of Prospective Teachers’ Noticing Skills Within Initial Teacher Education     

Tekin-Sitrava  Reyhan  Kaiser  Gabriele  Işıksal-Bostan  Mine 《International Journal of Science and Mathematics Education》2022,20(7):1611-1634

International Journal of Science and Mathematics Education - Although the effects of professional development programs on teachers’ noticing skills have attracted considerable interest among...  相似文献   

Student Engagement in a Flipped Secondary Mathematics Classroom     

Cevikbas  Mustafa  Kaiser  Gabriele 《International Journal of Science and Mathematics Education》2022,20(7):1455-1480

International Journal of Science and Mathematics Education - Many students are becoming increasingly disengaged in school, particularly in mathematics. This is an important problem as lack of...  相似文献   

The concept of public goods,the state,and higher education finance: a view from the BRICs     

Martin Carnoy  Isak Froumin  Prashant K. Loyalka  Jandhyala B. G. Tilak 《Higher Education》2014,68(3):359-378

Because higher education serves both public and private interests, the way it is conceived and financed is contested politically, appearing in different forms in different societies. What is public and private in education is a political–social construct, subject to various political forces, primarily interpreted through the prism of the state. Mediated through the state, this construct can change over time as the economic and social context of higher education changes. In this paper, we analyze through the state’s financing of higher education how it changes as a public/private good and the forces that impinge on states to influence such changes. To illustrate our arguments, we discuss trends in higher education financing in the BRIC countries—Brazil, Russia, India, and China. We show that in addition to increased privatization of higher education financing, BRIC states are increasingly differentiating the financing of elite and non-elite institutions.  相似文献   

Market information approaches, product innovativeness, and firm performance: An empirical study in the fashion industry     

Paola Cillo  Luigi M. De Luca  Gabriele Troilo 《Research Policy》2010,39(9):1242-1252

In this study the authors propose a distinction between two approaches to market information, rooted in the marked-based learning theory. The two approaches are conceptualized and operationalized on the basis of their differences along three processes: generation, dissemination and use of market information. In the retrospective approach, the generation process is based on expressed customer needs and extant market relations; the dissemination is based on formal mechanisms; the use process is more instrumental. In the forward-looking approach, the generation process is based on latent customer needs and on the evolutionary patterns of the future market relations; the dissemination process is more informal; the use of information is more conceptual. A series of hypotheses concerning the relationships between these approaches, product innovativeness and firm performance are tested on a sample of Italian fashion firms. Results suggest that the two approaches are complementary for firm performance, but have opposite effects on product innovativeness: while a forward-looking approach is positively related to product innovativeness, a retrospective approach seems to be negatively related. The results also shed light on how market information approaches and product innovativeness jointly affect firm performance.  相似文献   

Autonomy enhances running efficiency     

Takehiro Iwatsuki  James W. Navalta  Gabriele Wulf 《Journal of sports sciences》2019,37(6):685-691

Performer autonomy has been shown to contribute to effective motor performance and learning. Autonomy support is therefore a key factor in the OPTIMAL theory of motor learning (Wulf, G., & Lewthwaite, 2016). The purpose of the present study was to examine whether supporting individuals’ need for autonomy by giving them choices would increase movement efficiency. Such a finding would be consistent with the OPTIMAL theory prediction that autonomy facilitates the coupling of goals and actions. Participants (N = 32) were asked to run at a submaximal intensity (65% of VO₂ max) for 20 minutes. Before the run, participants in a choice group were able to choose 5 of 10 photos as well as the order in which they would be shown to them on a computer screen during the run. Control group participants were shown the same photos, in the same order, chosen by their counterparts in the choice group. Throughout the run, oxygen consumption and heart rate were significantly lower in the choice group than the control group. Thus, providing autonomy support resulted in enhanced running efficiency. The present findings are in line with the notion that autonomy facilitates goal-action coupling.  相似文献