Electronic perturbation of quinone methides (QM) greatly influences their stability and in turn alters the kinetics and product profile of QM reaction with deoxynucleosides. Consistent with the electron deficient nature of this reactive intermediate, electron-donating substituents are stabilizing and electron-withdrawing substituents are destabilizing. For example, a dC N3-QM adduct is made stable over the course of observation (7 days) by the presence of an electron-withdrawing ester group that inhibits QM regeneration. Conversely, a related adduct with an electron donating methyl group is very labile and regenerates its QM with a half-life of approximately 5 hr. The generality of these effects is demonstrated with a series of alternative quinone methide precursors (QMP) containing a variety of substituents attached at different positions with respect to the exocyclic methylene. The rates of nucleophilic addition to substituted QMs measured by laser flash photolysis similarly span five orders of magnitude with electron rich species reacting most slowly and electron deficient species reacting most quickly. The reversibility of QM reaction can now be predictably adjusted for any desired application.

Background Although spinal magnetic resonance imaging (MRI) findings of neuromyelitis optica (NMO) have been described, there is limited data available that help differentiate NMO from other causes of longitudinally extensive transverse myelitis (LETM). Objective To investigate the spinal MRI findings of LETM that help differentiate NMO at the acute stage from multiple sclerosis (MS) and other causes of LETM. Methods We enrolled 94 patients with LETM into our study. Bright spotty lesions (BSL), the lesion distribution and location were evaluated on axial T2-weighted images. Brainstem extension, cord expansion, T1 darkness and lesion enhancement were noted. We also reviewed the brain MRI of the patients during LETM. Results Patients with NMO had a greater amount of BSL and T1 dark lesions (p < 0.001 and 0.003, respectively). The lesions in NMO patients were more likely to involve greater than one-half of the spinal cord’s cross-sectional area; to enhance and be centrally-located, or both centrally- and peripherally-located in the cord. Of the 62 available brain MRIs, 14 of the 27 whom were NMO patients had findings that may be specific to NMO. Conclusions Certain spinal cord MRI features are more commonly seen in NMO patients and so obtaining brain MRI during LETM may support diagnosis.

MRI plays an increasingly important role in the workup of peripheral nerve injuries and may reveal severe nerve abnormalities before they are diagnosed by electrodiagnostic testing or a clinical examination. Sport-specific peripheral nerve injuries and their MRI appearance will be discussed in this article.

The widening income gap between specialists and primary care physicians (PCPs) has spurred many physician associations to reform the current Resource-Based Relative Value Scale fee schedule and sustainable growth rate expenditure target system. Hoping to better represent primary care, the American Association of Family Physicians formed a task force in 2011 to suggest supplements to the Relative Value Update Committee's procedural code recommendations to the Centers for Medicare and Medicaid Services. In addition, the predicted shortage of PCPs has caused many medical schools to increase class sizes; the scarcity of PCPs has also spurred the founding of new medical schools. Such measures, however, have not been met with more residency program sites or graduate medical education funding. The present article highlights major Medicare reform strategies and explores several issues affecting the field of primary care, including reimbursement, representation, and residency training.

No abstract

No abstract

No abstract

No abstract