Development of Peer Tutoring Services to Support Osteopathic Medical Students' Academic Success.

Context: Peer tutoring can benefit both tutors and tutored students, but information is lacking regarding establishing and measuring outcomes of such a program at new medical schools.

Objective: To examine the outcomes of a pilot peer tutoring initiative and explore the implications for long-term program development.

Methods: Fifty-one osteopathic medical students who participated in a pilot peer tutoring program during the 2013-2014 academic year were surveyed regarding satisfaction with the program.

Molecular and functional consequences of mutations in the central helix of cardiac troponin C.

The objective of this work was to investigate the role of acidic residues within the exposed middle segment of the central helix of cTnC in (1) cTnC-cTnI interactions, (2) Ca(2+) binding and exchange with the regulatory N-domain of cTnC in increasingly complex biochemical systems, and (3) ability of the cTn complex to regulate actomyosin ATPase. In order to achieve this objective, we introduced the D87A/D88A and E94A/E95A/E96A mutations into the central helix of cTnC. The D87A/D88A and E94A/E95A/E96A mutations decreased affinity of cTnC for the regulatory region of cTnI.

Effect of hypertrophic cardiomyopathy-linked troponin C mutations on the response of reconstituted thin filaments to calcium upon troponin I phosphorylation.

The objective of this work was to investigate the effect of hypertrophic cardiomyopathy-linked A8V and E134D mutations in cardiac troponin C (cTnC) on the response of reconstituted thin filaments to calcium upon phosphorylation of cardiac troponin I (cTnI) by protein kinase A. The phosphorylation of cTnI at protein kinase A sites was mimicked by the S22D/S23D double mutation in cTnI. Our results demonstrate that the A8V and E134D mutations had no effect on the extent of calcium desensitization of reconstituted thin filaments induced by cTnI pseudophosphorylation.

Hypertrophic cardiomyopathy-linked mutation D145E drastically alters calcium binding by the C-domain of cardiac troponin C.

The role of the C-domain sites of cardiac troponin C in the modulation of the calcium signal remains unclear. In this study, we investigated the effects of hypertrophic cardiomyopathy-linked mutations A8V, E134D, and D145E in cardiac troponin C on the properties of the C-domain sites. The A8V mutation had essentially no effect on the calcium or magnesium binding properties of the C-domain sites, while the mutation E134D moderately decreased calcium and magnesium binding affinities.

Effect of calcium-sensitizing mutations on calcium binding and exchange with troponin C in increasingly complex biochemical systems.

The calcium-dependent interactions between troponin C (TnC) and other thin and thick filament proteins play a key role in the regulation of cardiac muscle contraction. Five hydrophobic residues (Phe(20), Val(44), Met(45), Leu(48), and Met(81)) in the regulatory domain of TnC were individually substituted with polar Gln, to examine the effect of these mutations that sensitized isolated TnC to calcium on (1) the calcium binding and exchange with TnC in increasingly complex biochemical systems and (2) the calcium sensitivity of actomyosin ATPase. The hydrophobic residue mutations drastically affected calcium binding and exchange with TnC in increasingly complex biochemical systems, indicating that side chain intra- and intermolecular interactions of these residues play a crucial role in determining how TnC responds to calcium.