Bimolecular catalysis and turnover from a macromolecular host system.

The synthesis of a globular macromolecule and its application as a bimolecular catalyst are reported. The macromolecular structure supports (at least) two zinc-metalated porphyrin units, each capable of binding a single reactant. The proximity of the two bound reactants results in an increased local concentration, leading to a maximum 300-fold increase in the reaction rate. In contrast to other synthetic catalysts, where bidentate products inhibit further reactions, this macromolecular system allows the product to be displaced by the reactants leading to turnover and catalysis. We believe that this is due to the dynamics of the macromolecular host system, which maintains enough flexibility to adopt a favorable/reactive geometry, which allows the reactants to get close and react while possessing sufficient rigidity/poor geometry to reduce and disrupt any cooperative/inhibitive bidentate binding.

Nephrogenic systemic fibrosis in the podiatric patient.

Nephrogenic systemic fibrosis (NSF) is a severely debilitating disease that was first described in the literature by Cowper and colleagues in 2000. It is pertinent to the field of podiatry because patients with NSF first manifest cutaneous symptoms in the lower extremity in the form of fibrosing lesions. To date, these lesions have been documented only in people with moderate to severe kidney failure. There is speculation that gadolinium, used as a contrast agent for imaging, might be the inciting factor that triggers a cascade of events that results in the inappropriate fibrosis both in the dermis and in deeper tissues. Nephrogenic systemic fibrosis has been shown to cause these lesions in the lungs, pleura, diaphragm, myocardium, pericardium, and dura mater, the presence of which are typically indicative of severe progression of NSF. In cases where the lesions are manifest in the periarticular tissue, joint contractures and restricted range of motion can often result. We provide a quick synopsis of NSF, and a short case study that describes the authors' experience with one of their patients who requested a surgical consult as a result of being wheelchair-bound due to NSF's sequelae.