John J. Leddy

The muscle-specific calmodulin-dependent protein kinase assembles with the glycolytic enzyme complex at the sarcoplasmic reticulum and modulates the activity of glyceraldehyde-3-phosphate dehydrogenase in a Ca2+/calmodulin-dependent manner

The skeletal muscle specific Ca2+/calmodulin-dependent protein kinase (CaMKIIβM) is localized to the sarcoplasmic reticulum (SR) by an anchoring protein, αKAP, but its function remains to be defined. Protein interactions of CaMKIIβM indicated that it exists in complex with enzymes involved in glycolysis at the SR membrane. The kinase was found to complex with glycogen phosphorylase, glycogen debranching enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and creatine kinase in the SR membrane. CaMKIIβM was also found to assemble with aldolase A, GAPDH, enolase, lactate dehydrogenase, creatine kinase, pyruvate kinase, and phosphorylase b kinase from the cytosolic fraction. The interacting proteins were substrates of CaMKIIβM, and their phosphorylation was enhanced in a Ca2+- and calmodulin (CaM)-dependent manner. The CaMKIIβM could directly phosphorylate GAPDH and markedly increase (∼3.4-fold) its activity in a Ca2+/CaM-dependent manner. These data suggest that the muscle CaMKIIβM isoform may serve to assemble the glycogen-mobilizing and glycolytic enzymes at the SR membrane and specifically modulate the activity of GAPDH in response to calcium signaling. Thus, the activation of CaMKIIβM in response to calcium signaling would serve to modulate GAPDH and thereby ATP and NADH levels at the SR membrane, which in turn will regulate calcium transport processes.

The association of cardiac dystrophin with myofibrils/Z-disc regions in cardiac muscle suggests a novel role in the contractile apparatus.

Dystrophin serves a variety of roles at the cell membrane through its associations, and defects in the dystrophin gene can give rise to muscular dystrophy and genetic cardiomyopathy. We investigated localization of cardiac dystrophin to determine potential intracellular sites of association. Subcellular fractionation revealed that while the majority of dystrophin was associated with the sarcolemma, about 35% of the 427-kDa form of dystrophin was present in the myofibrils. The dystrophin homolog utrophin was detectable only in the sarcolemmal membrane and was absent from the myofibrils as were other sarcolemmal glycoproteins such as adhalin and the sodium-calcium exchanger. Extraction of myofibrils with KCl and detergents could not solubilize dystrophin. Dystrophin could only be dissociated from the myofibrillar protein complex in 5 M urea followed by sucrose density gradient centrifugation where it co-fractionated with one of two distinctly sedimenting peaks of actin. Immunoelectron microscopy of intracellular regions of cardiac muscle revealed a selective labeling of Z-discs by dystrophin antibodies. In the genetically determined cardiomyopathic hamster, strain CHF 147, the time course of development of cardiac insufficiency correlated with an overall 75% loss of myofibrillar dystrophin. These findings collectively show that a significant pool of the 427-kDa form of cardiac dystrophin was specifically associated with the contractile apparatus at the Z-discs, and its loss correlated with progression to cardiac insufficiency in genetic cardiomyopathy. The loss of distinct cellular pools of dystrophin may contribute to the tissue-specific pathophysiology in muscular dystrophy.

REGULATION OF DIHYDROPYRIDINE AND RYANODINE RECEPTOR GENE EXPRESSION IN SKELETAL MUSCLE : ROLE OF NERVE, PROTEIN KINASE C, AND CAMP PATHWAYS

The dihydropyridine (DHP) and ryanodine (RY) receptors play a critical role in depolarization-induced calcium release in skeletal muscle, yet the factors which govern their expression remain unknown. We investigated the roles of electrical activity and trophic factors in the regulation of the genes encoding the α, α, and β subunits of the DHP receptor as well as the RY receptor in rat skeletal muscle in vivo. Muscle paralysis, induced by denervation, had no effect on the DHP receptor mRNA levels while the RY receptor mRNA was decreased. In contrast, chronic superfusion of tetrodotoxin onto the sciatic nerve resulted in a marked increase in mRNA levels and transcriptional activity of both DHP and RY receptor genes. Since nerve can induce changes in second messenger pathways which modulate muscle gene expression, we attempted to identify factors which regulate DHP and RY receptor expression using cultured myotubes. Elevated cAMP levels specifically inhibited the expression of RY receptor mRNA while 12-O-tetradecanoylphorbol-13-acetate, an activator of protein kinase C, increased the transcripts encoding the RY receptor and the α subunit of the DHP receptor. Changes in the level of mRNAs were paralleled by altered receptor numbers. Neither cAMP nor protein kinase C altered transcriptional activity of the DHP and RY receptor genes. These results demonstrate that neural factor(s) regulate DHP and RY receptor mRNA levels in vivo via transcriptional mechanisms while protein kinase C and cAMP can modulate DHP and RY receptor transcript levels by a transcription-independent process.

Does an emotional intelligence test correlate with traditional measures used to determine medical school admission

Background As medical school admission committees are giving increased consideration to noncognitive measures, this study sought to determine how emotional intelligence (EI) scores relate to other traditional measures used in the admissions process. Method EI was measured using an ability-based test (Mayer-Salovey-Caruso Emotional Intelligence Test, or MSCEIT) in two consecutive cohorts of medical school applicants (2006 and 2007) qualifying for the admission interview. Pearson correlations between EI scores and traditional measures (i.e., weighted grade point average [wGPA], autobiographical sketch scores, and interview scores) were calculated. Results Of 659 applicants, 68% participated. MSCEIT scores did not correlate with traditional measures (r = −0.06 to 0.09, P > .05), with the exception of a small correlation with wGPA in the 2007 cohort (r = −0.13, P < .05). Conclusions The lack of substantial relationships between EI scores and traditional medical school admission measures suggests that EI evaluates a construct fundamentally different from traits captured in our admission process.

Student Perceptions of Independent versus Facilitated Small Group Learning Approaches to Compressed Medical Anatomy Education.

The purpose of this study was to compare student perceptions regarding two, small group learning approaches to compressed (46.5 prosection‐based laboratory hours), integrated anatomy education at the University of Ottawa medical program. In the facilitated active learning (FAL) approach, tutors engage students and are expected to enable and balance both active learning and progression through laboratory objectives. In contrast, the emphasized independent learning (EIL) approach stresses elements from the “flipped classroom” educational model: prelaboratory preparation, independent laboratory learning, and limited tutor involvement. Quantitative (Likert‐style questions) and qualitative data (independent thematic analysis of open‐ended commentary) from a survey of students who had completed the preclerkship curriculum identified strengths from the EIL (promoting student collaboration and communication) and FAL (successful progression through objectives) approaches. However, EIL led to student frustration related to a lack of direction and impaired completion of objectives, whereas active learning opportunities in FAL were highly variable and dependent on tutor teaching style. A “hidden curriculum” was also identified, where students (particularly EIL and clerkship students) commonly compared their compressed anatomy education or their anatomy learning environment with other approaches. Finally, while both groups highly regarded the efficiency of prosection‐based learning and expressed value for cadaveric‐based learning, student commentary noted that the lack of grade value dedicated to anatomy assessment limited student accountability. This study revealed critical insights into small group learning in compressed anatomy education, including the need to balance student active learning opportunities with appropriate direction and feedback (including assessment). Anat Sci Educ.

Does emotional intelligence at medical school admission predict future academic performance

Purpose Medical school admissions committees are increasingly considering noncognitive measures like emotional intelligence (EI) in evaluating potential applicants. This study explored whether scores on an EI abilities test at admissions predicted future academic performance in medical school to determine whether EI could be used in making admissions decisions. Method The authors invited all University of Ottawa medical school applicants offered an interview in 2006 and 2007 to complete the Mayer–Salovey–Caruso EI Test (MSCEIT) at the time of their interview (105 and 101, respectively), then again at matriculation (120 and 106, respectively). To determine predictive validity, they correlated MSCEIT scores to scores on written examinations and objective structured clinical examinations (OSCEs) administered during the four-year program. They also correlated MSCEIT scores to the number of nominations for excellence in clinical performance and failures recorded over the four years. Results The authors found no significant correlations between MSCEIT scores and written examination scores or number of failures. The correlations between MSCEIT scores and total OSCE scores ranged from 0.01 to 0.35; only MSCEIT scores at matriculation and OSCE year 4 scores for the 2007 cohort were significantly correlated. Correlations between MSCEIT scores and clinical nominations were low (range 0.12–0.28); only the correlation between MSCEIT scores at matriculation and number of clinical nominations for the 2007 cohort were statistically significant. Conclusions EI, as measured by an abilities test at admissions, does not appear to reliably predict future academic performance. Future studies should define the role of EI in admissions decisions.

Alternative splicing generates a CaM kinase IIβ isoform in myocardium that targets the sarcoplasmic reticulum through a putative αKAP and regulates GAPDH

We report the isolation of a full length cDNA from cardiac muscle that encodes a ∼73 kDa calcium/calmodulin (CaM) dependent kinase IIβ isoform (CaMKIIβC) that was generated by alternative splicing of the CaMKIIβ gene. Antipeptide antibodies raised to specific regions of the kinase identified a 73 kDa kinase polypeptide in cardiac SR. Anti-alpha kinase anchoring protein (αKAP) antibodies identified a 25 kDa polypeptide in cardiac SR and RT-PCR followed by sequence analysis confirmed the presence of a full length αKAP encoding transcript in myocardium. Protein interaction assays revealed that the 73 kDa CaMKIIβC binds GAPDH to modulate the production of NADH in a Ca2+/CaM dependent reaction. The presence of a CaMKIIβ isoform that can target the SR presumably via its membrane anchor αKAP defines a previously unrecognized Ca2+/CaM regulatory system in myocardium. (Mol Cell Biochem 270: 215–221, 2005)

Comparing alternative and traditional dissemination metrics in medical education

The impact of academic scholarship has traditionally been measured using citation‐based metrics. However, citations may not be the only measure of impact. In recent years, other platforms (e.g. Twitter) have provided new tools for promoting scholarship to both academic and non‐academic audiences. Alternative metrics (altmetrics) can capture non‐traditional dissemination data such as attention generated on social media platforms.

E2F6 Impairs Glycolysis and Activates BDH1 Expression Prior to Dilated Cardiomyopathy

Rationale The E2F pathway plays a critical role in cardiac growth and development, yet its role in cardiac metabolism remains to be defined. Metabolic changes play important roles in human heart failure and studies imply the ketogenic enzyme β-hydroxybutyrate dehydrogenase I (BDH1) is a potential biomarker. Objective To define the role of the E2F pathway in cardiac metabolism and dilated cardiomyopathy (DCM) with a focus on BDH1. Methods and Results We previously developed transgenic (Tg) mice expressing the transcriptional repressor, E2F6, to interfere with the E2F/Rb pathway in post-natal myocardium. These Tg mice present with an E2F6 dose dependent DCM and deregulated connexin-43 (CX-43) levels in myocardium. Using the Seahorse platform, a 22% decrease in glycolysis was noted in neonatal cardiomyocytes isolated from E2F6-Tg hearts. This was associated with a 39% reduction in the glucose transporter GLUT4 and 50% less activation of the regulator of glucose metabolism AKT2. The specific reduction of cyclin B1 (70%) in Tg myocardium implicates its importance in supporting glycolysis in the postnatal heart. No changes in cyclin D expression (known to regulate mitochondrial activity) were noted and lipid metabolism remained unchanged in neonatal cardiomyocytes from Tg hearts. However, E2F6 induced a 40-fold increase of the Bdh1 transcript and 890% increase in its protein levels in hearts from Tg pups implying a potential impact on ketolysis. By contrast, BDH1 expression is not activated until adulthood in normal myocardium. Neonatal cardiomyocytes from Wt hearts incubated with the ketone β-hydroxybutyrate (β-OHB) showed a 100% increase in CX-43 protein levels, implying a role for ketone signaling in gap junction biology. Neonatal cardiomyocyte cultures from Tg hearts exhibited enhanced levels of BDH1 and CX-43 and were not responsive to β-OHB. Conclusions The data reveal a novel role for the E2F pathway in regulating glycolysis in the developing myocardium through a mechanism involving cyclin B1. We reveal BDH1 expression as an early biomarker of heart failure and its potential impact, through ketone signaling, on CX-43 levels in E2F6-induced DCM.

Benefits of extracurricular participation in dissection in a prosection‐based medical anatomy program

The purpose of this study was to evaluate the extracurricular cadaveric dissection program available to medical students at an institution with a modern (time‐compressed, student‐centered, and prosection‐based) approach to medical anatomy education. Quantitative (Likert‐style questions) and qualitative data (thematic analysis of open‐ended commentary) were collated from a survey of three medical student cohorts who had completed preclerkship. Perceived benefits of dissection included the hands‐on learning style and the development of anatomy expertise, while the main barrier that limited participation was the time‐intensive nature of dissection. Despite perceived benefits, students preferred that dissection remain optional. Analysis of assessments for the MD2016 cohort revealed that dissection participation was associated with enhanced performance on anatomy items in each systems‐based unit examination, with the largest benefits observed on discriminating items that assessed knowledge application. In conclusion, this study revealed that there are academic and perceived benefits of extracurricular participation in dissection. While millennial medical students recognized these benefits, these students also indicated strong preference for having flexibility and choice in their anatomy education, including the choice to participate in cadaveric dissection. Anat Sci Educ 11: 294–302.