Characterization of stereochemistry and molecular conformation using solid-state NMR tensors.

A solid-state NMR technique is described for establishing stereochemistry using the natural product terrein as a model compound. This method involves comparison of experimental (13)C tensor principal values with ab initio computed values for all possible computer-generated stereoisomers. In terrein the relative stereochemistry is confirmed by NMR to be 2R*,3S with high statistical probability (>99.5%). The proposed approach also simultaneously verifies the molecular conformation of the two hydroxy groups in terrein established by X-ray data. It is sufficient to use only shift tensor values at carbons 2 and 3, the stereocenters, to characterize both the stereochemistry and molecular conformations. The solid-state NMR method appears to be especially useful for determining relative stereochemistry of compounds or their derivatives that are difficult to crystallize.

Fitting of low-intensity wide-line spectra dominated by chemical shift anisotropy.

How experimental parameters affect the appearance, and consequently the fitting, of signals having very wide lines is discussed. As these spectra usually have very low intensities, pulse sequences that remove acoustic ringing and other experimental artefacts have to be used. These pulse sequences introduce further spectral distortions. A FORTRAN 77 program was developed that accounts for these effects. The fitting of these broad spectra is demonstrated by application to 207Pb solid-state nuclear magnetic resonance (NMR) spectra.

Office education by pediatricians to increase seat belt use.

We studied promoting seat belt use by school-aged children through discussions with their pediatricians. The study population consisted of 242 well children observed coming to and leaving from a private pediatric practice. Only four (5%) of 73 control patients who did not wear their seat belts coming in wore them going out. For intervention patients, this figure was 29 (38%) of 77. At one-year follow-up by questionnaire, there were no statistical differences between the percentage of seat belt use in control (67%) vs intervention (62%) patients. However, pediatricians' reported percentage of patients routinely counseled about seat belt use prior to the start of the study was highly correlated with patients' observed prestudy seat belt use. Pediatricians should include education about automobile safety as a part of all well-child visits.