Constance Bowe

Case method teaching: An effective approach to integrate the basic and clinical sciences in the preclinical medical curriculum

Background: Recent efforts to identify the essential skills and competencies required for medical practice have resulted in an expansion of the educational outcomes for which medical schools are accountable. Teachers in the preclinical years, formerly focused on the transmission of biomedical principles and factual information, are now charged with presenting discipline-specific concepts with an emphasis on clinical relevance while advancing active learning, critical thinking, communication skills, and other professional competencies. Problem-based learning has been widely introduced to support these educational goals but other, less resource-intensive, discussion methodologies have not been extensively explored. Aim: To examine the feasibility of case-method teaching (CMT) during the preclinical curricula to integrate basic science concepts in the management of clinical problems. Methods: CMT sessions were conducted with students during the first- and second-year of hybrid curricula at two US medical schools. Results: First- and second-year medical classes of 40–95 students prepared for and actively engaged in single session case discussions and were able to productively apply basic science principles in clinical problem-solving. Conclusion: CMT represents a feasible and resource-conservative pedagogical format to promote critical thinking and to integrate basic science principles during the preclinical curriculum.

D-2-Hydroxyglutaric Aciduria

Hydroxyglutaric aciduria is detected by gas chromatographic-mass spectrometric analysis, and the D and L forms are quantified by chemical ionization with deuterated internal standards. Patients have recently been described who accumulate the D form, and they appear to be quite different from those with the more common L form. Experience is reported with three patients and an animal model with D-2-hydroxyglutaric aciduria. The phenotype appears to include mental retardation, macrocephaly, hypotonia, seizures, and involuntary movements, although neurologic and systemic manifestations of the disorder varied considerably between individual patients, even within the same family. (J Child Neurol 1995;10:137-142).

Choline acetyltransferase mutations in myasthenic syndrome due to deficient acetylcholine resynthesis.

The myasthenic syndrome due to abnormal acetylcholine resynthesis is characterized by early onset, recessive inheritance, and recurrent episodes of potentially fatal apnea. Mutations in the gene encoding choline acetyltransferase (CHAT) have been found to account for this condition. We have identified five patients from three independent families with features of this disease including, in four patients, a paradoxical worsening of symptoms with cold temperatures. Electrodiagnostic studies demonstrated impaired neuromuscular transmission in all patients. In vitro microelectrode studies performed in the anconeus muscle biopsies of two patients showed moderate reduction of quantal release. Electron microscopy of the neuromuscular junction was normal in both patients. Each patient had two heterozygous CHAT mutations including L210P and P211A (family 1), V194L and V506L (family 2), and R548stop and S694C (family 3). Three of these mutations have previously been reported and suggest that, in this syndrome, some molecular defects may be more prevalent than others. Muscle Nerve 27: 180–187, 2003

Presynaptic congenital myasthenic syndrome due to quantal release deficiency

Objective: To provide clinical, electrophysiologic, and ultrastructural findings in three patients with a presynaptic congenital myasthenic syndrome (CMS). Background: Familial infantile myasthenia and paucity of synaptic vesicles are the only two fully characterized CMS. We are describing here three patients with another form of presynaptic CMS characterized by deficiency of the action potential–dependent release without reduction of the spontaneous release of neurotransmitter from the nerve terminal. Methods: The authors performed electromyography and anconeus muscle biopsies that included intracellular recordings and electron microscopy of the neuromuscular junction in three patients with presynaptic CMS. They also sequenced part of the P/Q-calcium α1-subunit gene (CACNA1A) and the acetylcholine receptor subunit (AChR) genes in these patients. Results: In these patients there were additional neurologic findings including nystagmus and ataxia. In all three patients the end-plate potential quantal content (m) was markedly reduced but neither the amplitudes nor the frequencies of miniature end-plate potentials were diminished. Ultrastructurally, postsynaptic end-plate folds, nerve terminal size, and synaptic vesicle number were normal but double-membrane-bound sacs containing synaptic vesicles were present in the nerve terminal of all three patients. The screening of reported pathogenic mutations in the CACNA1A and a mutational analysis of AChR subunit genes were negative. Conclusion: This form of CMS appears to result only from a deficiency of the quantal release of neurotransmitter that may be due to an abnormal calcium mechanism or impaired endocytosis and recycling of synaptic vesicles.

Variable phenotypes associated with mutations in DOK7

Many patients with the limb‐girdle variant of congenital myasthenic syndrome (CMS) possess mutations in the human Dok‐7 gene (DOK7). We identified six unrelated CMS patients with DOK7 mutations. Two patients, one mildly and the other moderately affected, were homozygous for the previously described 1263insC mutation. The common 1124_1127dupTGCC mutation was detected in the other four patients, whose clinical phenotypes range from mildly to severely affected. This striking phenotypic heterogeneity found both within and between mutational classes is made more compelling by data from our electrophysiological studies and electron microscopy of the neuromuscular junction (NMJ). Indeed, several aspects of the physiological and morphometric data do not correlate with genotype or severity of clinical phenotype. Overall, our study corroborates the findings of others and provides an additional demonstration of the considerable phenotypic variability associated with CMS due to DOK7 mutations. Muscle Nerve, 2008

Rapsyn mutations in myasthenic syndrome due to impaired receptor clustering

Rapsyn, a 43‐kDa postsynaptic protein, is essential for anchoring and clustering acetylcholine receptors (AChRs) at the endplate (EP). Mutations in the rapsyn gene have been found to cause a postsynaptic congenital myasthenic syndrome (CMS). We detected six patients with CMS due to mutations in the rapsyn gene (RAPSN). In vitro studies performed in the anconeus muscle biopsies of four patients showed severe reduction of miniature EP potential amplitudes. Electron microscopy revealed various degrees of impaired development of postsynaptic membrane folds. All patients carried the N88K mutation. Three patients were homozygous for N88K and had less severe phenotypes and milder histopathologic abnormalities than the three patients who were heterozygous and carried a second mutation (either L14P, 46insC, or Y269X). Surprisingly, two N88K homozygous patients had one asymptomatic relative each who carried the same genotype, suggesting that additional genetic factors to RAPSN mutations are required for disease expression. Muscle Nerve 28: 293–301, 2003

Questioning the 'big assumptions'. Part II: recognizing organizational contradictions that impede institutional change

Background Well‐designed medical curriculum reforms can fall short of their primary objectives during implementation when unanticipated or unaddressed organizational resistance surfaces. This typically occurs if the agents for change ignore faculty concerns during the planning stage or when the provision of essential institutional safeguards to support new behaviors are neglected. Disappointing outcomes in curriculum reforms then result in the perpetuation of or reversion to the Status quo despite the loftiest of goals.

Questioning the "big assumptions". Part I: addressing personal contradictions that impede professional development.

Background The ultimate success of recent medical curriculum reforms is, in large part, dependent upon the facultys ability to adopt and sustain new attitudes and behaviors. However, like many New Years resolutions, sincere intent to change may be short lived and followed by a discouraging return to old behaviors. Failure to sustain the initial resolve to change can be misinterpreted as a lack of commitment to ones original goals and eventually lead to greater effort expended in rationalizing the status quo rather than changing it.

Systems-Based Practice in Graduate Medical Education: Systems Thinking as the Missing Foundational Construct

Background: Since 2001, residencies have struggled with teaching and assessing systems-based practice (SBP). One major obstacle may be that the competency alone is not sufficient to support assessment. We believe the foundational construct underlying SBP is systems thinking, absent from the current Accreditation Council for Graduate Medical Education competency language. Summary: Systems thinking is defined as the ability to analyze systems as a whole. The purpose of this article is to describe psychometric issues that constrain assessment of SBP and elucidate the role of systems thinking in teaching and assessing SBP. Conclusion: Residency programs should incorporate systems thinking models into their curricula. Trainees should be taught to understand systems at an abstract level, in order to analyze their own healthcare systems, and participate in quality and patient safety activities. We suggest that a developmental trajectory for systems thinking be developed, similar to the model described by Dreyfus and Dreyfus.

Choline Acetyltransferase Mutations Causing Congenital Myasthenic Syndrome: Molecular Findings and Genotype–Phenotype Correlations

Choline acetyltransferase catalyzes the synthesis of acetylcholine at cholinergic nerves. Mutations in human CHAT cause a congenital myasthenic syndrome due to impaired synthesis of ACh; this severe variant of the disease is frequently associated with unexpected episodes of potentially fatal apnea. The severity of this condition varies remarkably, and the molecular factors determining this variability are poorly understood. Furthermore, genotype–phenotype correlations have been difficult to establish in patients with biallelic mutations. We analyzed the protein expression of phosphorylated ChAT of seven CHAT mutations, p.Val136Met, p.Arg207His, p.Arg186Trp, p.Val194Leu, p.Pro211Ala, p.Arg566Cys, and p.Ser694Cys, in HEK‐293 cells to phosphorylated ChAT, determined their enzyme kinetics and thermal stability, and examined their structural changes. Three mutations, p.Arg207His, p.Arg186Trp, and p.Arg566Cys, are novel, and p.Val136Met and p.Arg207His are homozygous in three families and associated with severe disease. The characterization of mutants showed a decrease in the overall catalytic efficiency of ChAT; in particular, those located near the active‐site tunnel produced the most seriously disruptive phenotypic effects. On the other hand, p.Val136Met, which is located far from both active and substrate‐binding sites, produced the most drastic reduction of ChAT expression. Overall, CHAT mutations producing low enzyme expression and severe kinetic effects are associated with the most severe phenotypes.