Theoretical and infrared spectroscopy study of the conformational preferences for some 3-monosubstituted-2-methylpropenes.

The infrared spectra of 3-X-2-methylpropenes (X = Cl, Br, I, NMe(2), NEt(2), OH, OMe, OEt, SH, SMe and SEt) have been recorded at room temperature in CCl(4) solution. The C=C stretching mode was analyzed and compared to theoretically calculated data to give insight about the conformational isomerism of these compounds. A combination band systematically appears in all spectra (except for amines); the remaining ν(C=C) band and the corresponding intensities were used to obtain the conformer populations. For second-period atoms bonded to C-3, two or more conformers are observed in CCl(4) solution, but when substitution by heavier atoms takes place, only one conformer is observed under the tested conditions, i.e., the gauche form with respect to the C=C-C-X dihedral angle. Therefore, steric hindrance between X and =CH(2) in the s-cis form is strongly dependent on the heteroatom size, while the effect of the alkyl chain bonded to the heteroatom seems to be of secondary importance.

Evaluation of seminal citrate level by 1H nuclear magnetic resonance spectroscopy in men with spinal cord injury.

STUDY DESIGN: A case-control evaluating seminal citrate in patients with spinal cord injury (SCI). OBJECTIVE: Several studies have shown neurological prostatic dysfunction in patients with SCI, as confirmed by low levels of seminal prostate-specific antigen (PSA), which is used as a parameter of gland activity. However, seminal citrate, produced almost exclusively by the prostate, could also be used as a marker of prostate function. Thus, the objective of this study was to determine whether SCI causes any changes in seminal citrate concentration and to compare the results obtained for patients and healthy men (controls). SETTING: The study was carried out in Brazil. METHODS: We studied 30 men with SCI aged on average 37.77+/-10.04 years and 30 controls aged on average 38.03+/-10.06 years. Blood and semen samples were collected after 3 days of abstinence from ejaculation. Fifteen minutes after collection, semen was stored in liquid nitrogen and the samples were submitted to (1)H nuclear magnetic resonance ((1)H NMR). Serum was stored at a controlled temperature of -70 to -79 degrees C and later used for the determination of testosterone, prolactin and total PSA using an AxSYM instrument and Abbott reagents. RESULTS: The median concentration of seminal citrate was significantly lower in patients than in controls (521.65 versus 858.30 mg per 100 ml, P<0.001). CONCLUSIONS: Patients with SCI have a significant reduction of seminal citrate as a consequence of neurological dysfunction of the prostate.