RESUMO
Two bis-tridentate chelated cobalt(ii) complexes, which differ in the ligand structure by a methylene group, activate molecular oxygen (O2), and give different oxidation products. The O2 reaction of [CoII(pepma)2]2+ (1) with unsymmetrical 2-(2-pyridyl)-N-(2-pyridylmethyl)ethanamine (pepma) results in ligand oxidation, to the corresponding Co(ii) imine complex [CoII(pepmi)2]2+ (2). Contrastingly, the Co(ii) complex [CoII(bpma)2]2+ (3) of similar symmetrical bis(2-pyridylmethyl)amine (bpma), undergoes metal oxidation, yielding a cobalt(iii) complex, [CoIII(bpma)2]2+ (4). The reversibility of the amine to imine conversion and the stability of the Co(ii) imine complex (2) are investigated. Furthermore, the solution dynamics of Co(ii) complexes are highlighted with the help of paramagnetic 1H-NMR spectroscopy.
RESUMO
BACKGROUND: Bezoars are concretions of ingested matter which accumulate in the gastrointestinal tract and manifest as symptomatic foreign bodies. The aim of this study is to evaluate the incidence of gastric bezoars after lung transplantation and identify associated risk factors. METHODS: We performed a retrospective analysis of patients who underwent lung transplantation from December, 1992 through July, 2005 at our tertiary care medical center. Patients who had endoscopically confirmed gastrointestinal bezoars in the posttransplant setting were identified and compared with patients without bezoars. RESULTS: Of the 215 patients who received lung transplantation, 17 (7.9%) developed gastric bezoars confirmed by upper endoscopy. Cystic fibrosis was the leading indication for lung transplantation (n=145), and 11% of cystic fibrosis patients (16 of 145) formed gastric bezoars after transplant. Additionally, 94% of patients with bezoars (16 of 17) had cystic fibrosis (P=0.02), with the exception being a subject with primary ciliary dyskinesia. No patient who underwent lung transplant for another indication was found to have a bezoar. The mean time to diagnosis was 34 days, with two-thirds of bezoars diagnosed within one month after transplant. The annual incidence was unchanged during the study period. CONCLUSIONS: Gastric bezoars are common in cystic fibrosis patients after lung transplantation. The etiology is likely multifactorial, related to gastric motility, respiratory secretions, and medications. Further investigation is needed to understand the pathogenesis of bezoar formation in this selected population, and strategies for primary prevention may be beneficial.