Preconceptional Folate Supplementation and the Risk of Spontaneous Preterm Birth: A Cohort Study

In an analysis of a cohort of pregnant women, Radek Bukowski and colleagues describe an association between taking folic acid supplements and a reduction in the risk of preterm birth

Lateral laryngopharyngeal diverticula: a videofluoroscopic study of laryngopharyngeal wall in wind instrumentalists

CONTEXT: This paper analyze healthy musicians who play wind instruments. OBJECTIVE: To identify possible diverticular formations on the laryngopharyngeal wall produced by pharyngeal overpressure during the use of these instruments. METHODS: Through a videofluoroscopic method, 22 professional musicians had their pharynx analyzed in frontal face and profile, by swallowing 20 mL of barium sulfate solution and blowing against resistance. RESULTS: All the volunteers showed lateral laryngopharyngeal diverticula (3 unilateral and 19 bilateral) with areas ranging from 0.7 to 6 cm². Trumpet and clarinet players showed larger diverticula, on both the right and left sides. Any important complaints were noted spontaneously or after questions. In the barium-swallow analyses, the 41 diverticula previously identified in the blowing tests were not seen or appeared to be smaller, because of the free flux passage from the pharynx to the esophagus. Despite the existence of the other, less resistant areas on the laryngopharyngeal segment, no other protrusions could be found in this group of wind instrumentalists. CONCLUSIONS: The lateral laryngopharyngeal diverticula that occur in blow instrumentalists is distinct of diverticula produced by laryngopharyngeal overpressure determined by abnormally high resistance to flux passage from pharynx to esophagus. In musicians is the persistent and continuous pharyngeal overpressure induced by the resistance of the instrument's mouthpiece will strongly distend the anatomically less resistant areas of the pharynx, producing a large protrusion. Laryngopharyngeal overpressure without abnormal resistance to flux passage explain the way blow instrumentalists protrusions did not appear as full sacs in a barium-swallow test, despite their larger dimensions. As final conclusion the musician-acquired diverticula must be considered as an "occupational overuse syndrome"

A theoretical study of 1:1 and 1:2 complexes of acetylene with nitrosyl hydride

Ab initio calculations at MP2 computational level using aug-cc-pVTZ basis set were used to analyze the interactions between 1:1 and 1:2 complexes of acetylene and nitrosyl hydride. The structures obtained have been analyzed with the atoms in molecules and the density functional theory-symmetry adapted perturbation theory methodologies. Four minima were located on the potential energy surface of the 1:1 complex. Twenty-four different structures have been obtained for the 1:2 complexes. Five types of interactions are observed, CH·O, CH·N, NH·π hydrogen bonds and orthogonal interactions between the π clouds of triple bond, or the lone pair of oxygen with the electron-deficient region of the nitrogen atom. Stabilization energies of the 1:1 and 1:2 clusters including basis set superposition error and ZPE are in the range 3-8 and 6-17 kJ mol -1 at MP2/aug-cc-pVTZ computational level, respectively. Blue shift of NH bond upon complex formation in the ranges between 18-30 and 20-96 cm -1 is predicted for 1:1 and 1:2 clusters, respectively. The total nonadditive energy in the 1:2 cluster, calculated as the sum of the supermolecular nonadditive MP2 energy and the three-body dispersion energy, presents values between - 1.48 and 1.20 kJ mol -1. © Springer Science+Business Media, LLC 2011.Peer Reviewe