Manchester Clinical Placement Index (MCPI): Conditions for medical students’ learning in hospital and community placements

The drive to quality-manage medical education has created a need for valid measurement instruments. Validity evidence includes the theoretical and contextual origin of items, choice of response processes, internal structure, and interrelationship of a measure’s variables. This research set out to explore the validity and potential utility of an 11-item measurement instrument, whose theoretical and empirical origins were in an Experience Based Learning model of how medical students learn in communities of practice (COPs), and whose contextual origins were in a community-oriented, horizontally integrated, undergraduate medical programme. The objectives were to examine the psychometric properties of the scale in both hospital and community COPs and provide validity evidence to support using it to measure the quality of placements. The instrument was administered twice to students learning in both hospital and community placements and analysed using exploratory factor analysis and a generalizability analysis. 754 of a possible 902 questionnaires were returned (84% response rate), representing 168 placements. Eight items loaded onto two factors, which accounted for 78% of variance in the hospital data and 82% of variance in the community data. One factor was the placement learning environment, whose five constituent items were how learners were received at the start of the placement, people’s supportiveness, and the quality of organisation, leadership, and facilities. The other factor represented the quality of training—instruction in skills, observing students performing skills, and providing students with feedback. Alpha coefficients ranged between 0.89 and 0.93 and there were no redundant or ambiguous items. Generalisability analysis showed that between 7 and 11 raters would be needed to achieve acceptable reliability. There is validity evidence to support using the simple 8-item, mixed methods Manchester Clinical Placement Index to measure key conditions for undergraduate medical students’ experience based learning: the quality of the learning environment and the training provided within it. Its conceptual orientation is towards Communities of Practice, which is a dominant contemporary theory in undergraduate medical education

Crystal Structure Analysis Reveals Functional Flexibility in the Selenocysteine-Specific tRNA from Mouse

Selenocysteine tRNAs (tRNA(Sec)) exhibit a number of unique identity elements that are recognized specifically by proteins of the selenocysteine biosynthetic pathways and decoding machineries. Presently, these identity elements and the mechanisms by which they are interpreted by tRNA(Sec)-interacting factors are incompletely understood.We applied rational mutagenesis to obtain well diffracting crystals of murine tRNA(Sec). tRNA(Sec) lacking the single-stranded 3'-acceptor end ((ΔGCCA)RNA(Sec)) yielded a crystal structure at 2.0 Å resolution. The global structure of (ΔGCCA)RNA(Sec) resembles the structure of human tRNA(Sec) determined at 3.1 Å resolution. Structural comparisons revealed flexible regions in tRNA(Sec) used for induced fit binding to selenophosphate synthetase. Water molecules located in the present structure were involved in the stabilization of two alternative conformations of the anticodon stem-loop. Modeling of a 2'-O-methylated ribose at position U34 of the anticodon loop as found in a sub-population of tRNA(Sec)in vivo showed how this modification favors an anticodon loop conformation that is functional during decoding on the ribosome. Soaking of crystals in Mn(2+)-containing buffer revealed eight potential divalent metal ion binding sites but the located metal ions did not significantly stabilize specific structural features of tRNA(Sec).We provide the most highly resolved structure of a tRNA(Sec) molecule to date and assessed the influence of water molecules and metal ions on the molecule's conformation and dynamics. Our results suggest how conformational changes of tRNA(Sec) support its interaction with proteins