Dirk Everaert

Reproducibility of a survey questionnaire for the investigation of low back problems in adolescents

A test‐retest design was used to investigate the reproducibility of the results obtained using a survey questionnaire for low back problems in adolescents. A 1‐wk interval between test and retest was chosen. Participants were recruited from four schools. Selection of schools was based on geographic location, size of the school and educational level. Sixty‐seven adolescents (mean age= 16.62 y; SD = 0.57; range = 16–18) suffering from low back problems agreed to participate. A questionnaire on perceived characteristics of back problems and functional limitations was designed. Item completion rate and the reproducibility of results were investigated by means of percentage agreement and (weighted) kappa. High levels of reproducibility were found for items that evaluated perceived characteristics of back problems and functional limitations (Kw= 0.70‐0.93). Results suggest that the questionnaire used in the present study provided reproducible information. Detailed information on low back problems in adolescents could be obtained using this questionnaire.

Comparison of self‐administration and face‐to‐face interview for surveys of low back pain in adolescents

The aim of this study was to compare self‐administration with face‐to‐face interview in the investigation of low back pain in adolescents. Fifty‐seven adolescents with low back pain (mean age 17.3 y; range 16–18) first completed a questionnaire and were then invited to an interview. Analysis included item completion, percentages of agreement and weighted kappa. Item completion rates were high and comparable between self‐administration and interview. Information between both methods was analogous for severity and localization of problems, sleep behaviour, medical consultation and sports/leisure activities. Onset, progression, duration of low back pain and some items on the influence of movement/positions presented less comparable data.

Conformational analysis of substituent effects on the sugar puckering mode and the anti-HIV activity of 2',3'-dideoxypyrimidine nucleosides

A comparison between the conformational parameters of eleven active and inactive anti-HIV 2′,3′-dideoxypyrimidine nucleosides and a series of 73 uridine and thymidine structures, revealed that our compounds, all having N-glycosidic bond torsion angles χ in the anti range, have pseudorotation phase angles P well distributed over both N (C3′-endo) and S [C2′-endo and C3′-exo) type sugar conformations and have both +sc and ap C4′-C5′ conformations. This means that solid state conformations characterized by P, χ and γ do not provide decisive information for predicting possible anti-HIV activity. We also found that any rationalization of the activity or inactivity of nucleosides in terms of the gauche effect of electronegative substituents on the furanose ring conformation, could not be demonstrated by using the semiempirical quantum chemical AM 1 method. Calculations of C3′-X3′ bond polarities indicate that anti-HIV activity in C3′-substituted nucleoside analogues is consistent with the presence of a positive C3′-X3′ bond polarity. Exploration of the conformational space of χ vs. γ for C3′-endo, C2′-endo and C3′-exo sugar puckering modes using the same AM1 method, reveals that although the C3′-endo [P = 10°) region is about 2 kcal mol−1 lower than the C2′-endo region (P = 170°), the C2′ -endo sugar puckering mode is the most accessible one due to the conformational flexibility about the minima. Our results also suggest that as P increases from 10°, through 170°, to 210°, the preferred range for -y dramatically shifts from almost exclusively around 50° (+sc) at P = 10° to almost exclusively non +sc at P = 210°.

Synthesis and Structure of 2′,3′-Dideoxy-3′-fluoro-5-cyanouridine

Abstract The title compound was prepared by reaction of the 5-bromo congener with potassium cyanide in DMF. X-ray analysis revealed its solid state structure and the obtained conformation was compared to the con-formation of 3′-azido-3′-deoxythymidine (AZT) and of 2′,3′-dideoxy-3′-fluoro-5-chlorouridine, respectively, two very selective anti-HIV agents. They both show two separate molecules in their asymmetric unit, one of each fairly resembling the conformation of the title compound 4. The latter, however, displayed only very moderate activity.