Urdu version of the neck disability index: a reliability and validity study.

BACKGROUND: Despite the wide use of the neck disability index (NDI) for assessing disability in patients with neck pain, the NDI has not yet been translated and validated in Urdu. The first purpose of the present study was to translate and cross-culturally adapt the NDI into the Urdu language (NDI-U). The second purpose was to investigate the reliability, validity and responsiveness of the NDI-U in Urdu-speaking patients experiencing chronic mechanical neck pain (CMNP). METHODS: Translation and cross-cultural adaptation of the original version of the NDI were carried out using previously described procedures. Seventy-six patients with CMNP and thirty healthy participants were recruited for the study. NDI-U and visual analogue scales for pain intensity (VASpain) and disability (VASdisability) were administered to all the participants at baseline and to the patients 3 weeks after receiving physiotherapy intervention. The global rating of change scale (GROC) was also administered at this time. Test-retest reliability and internal consistency were carried out on forty-six randomly selected patients two days after they completed the NDI-U. The NDI-U was evaluated for factor analysis, content validity, construct validity (discriminative and convergent validity) and responsiveness. RESULTS: An intra-class correlation coefficient (ICC2,1) revealed excellent test-retest reliability for all items (ICC2,1 = 0.86-0.98) and total scores (ICC2,1 = 0.99) of the NDI-U. The NDI-U was found internally consistent with a Cronbach's alpha of 0.90 and a fair to good correlation between single items and the NDI-U total scores (r = 0.34 to 0.89). Factor analysis of the NDI-U produced two factors explaining 66.71% of the variance. Content validity was good, as no floor or ceiling effects were detected for the NDI-U total score. To determine discriminative validity, an independent t-test revealed a significant difference in the NDI-U total scores between the patients and healthy controls (P < 0.001). For convergent validity, Pearson's correlation coefficient showed a strong correlation between NDI-U and VASdisability (r = 0.83, P < 0.001) and a moderate correlation between NDI-U and VASpain (r = 0.62, P < 0.001). To measure responsiveness, an independent t-test showed a significant difference in the NDI-U change scores between the stable and the improved groups (P < 0.001). Furthermore, moderate correlations were found between the NDI-U change scores and the GROC (r = 0.50, P < 0.001), VASdisability change scores (r = 0.58, P < 0.001) and VASpain change scores (r = 0.55, P < 0.001). CONCLUSION: The results showed that the NDI-U is a reliable, valid and responsive questionnaire to measure disability in Urdu-speaking patients with CMNP.

Solvent Effect on the Photolysis of Riboflavin.

The kinetics of photolysis of riboflavin (RF) in water (pH 7.0) and in organic solvents (acetonitrile, methanol, ethanol, 1-propanol, 1-butanol, ethyl acetate) has been studied using a multicomponent spectrometric method for the assay of RF and its major photoproducts, formylmethylflavin and lumichrome. The apparent first-order rate constants (k obs) for the reaction range from 3.19 (ethyl acetate) to 4.61 × 10(-3) min(-1) (water). The values of k obs have been found to be a linear function of solvent dielectric constant implying the participation of a dipolar intermediate along the reaction pathway. The degradation of this intermediate is promoted by the polarity of the medium. This indicates a greater stabilization of the excited-triplet states of RF with an increase in solvent polarity to facilitate its reduction. The rate constants for the reaction show a linear relation with the solvent acceptor number indicating the degree of solute-solvent interaction in different solvents. It would depend on the electron-donating capacity of RF molecule in organic solvents. The values of k obs are inversely proportional to the viscosity of the medium as a result of diffusion-controlled processes.

Multicomponent spectrometric assay of cyanocobalamin and its photoproduct hydroxocobalamin in the presence of ascorbic acid in photolyzed solutions.

The simultaneous determination of cyanocobalamin (CC), hydroxocobalamin (HC) and ascorbic acid (AA) in aqueous solution has been achieved by a multicomponent spectrometric method. CC undergoes photolysis in acidic and alkaline media to form HC and the reaction is enhanced in the presence of AA. The method has been used to evaluate the kinetics of photodegradation reactions of the vitamin. CC, HC and AA present in the photolyzed solutions have been determined by absorbance measurement at 550, 525 and 265 nm at pH 4.0. These wavelengths correspond to the absorption maxima of the three substances and thus provide high specificity and sensitivity to the method. The method has been validated with respect to various parameters relating to the analytical performance characteristics. The recovery of the method for the three compounds ranges from 97.1-103.0% with a RSD value of ±3%. The accuracy of the method is shown by the linearity of the kinetic plots in the concentration range studied. The method is simple, rapid and convenient for the proposed work.

Correction for irrelevant absorption in multicomponent spectrophotometric assay of riboflavin, formylmethylflavin, and degradation products: kinetic applications.

In the spectrophotometric assay of multicomponent systems involved in drug degradation studies, some minor or unknown degradation products may be present. These products may interfere in the assay and thus invalidate the results due to their absorption in the range of analytical wavelengths. This interference may be eliminated by the application of an appropriate correction procedure to obtain reliable data for kinetic treatment. The present study is based on the application of linear and non-linear irrelevant absorption corrections in the multicomponent spectrophotometric assay of riboflavin and formylmethylflavin during the photolysis and hydrolysis studies. The correction procedures take into account the interference caused by minor or unknown products and have shown considerable improvement in the assay data in terms of the molar balance. The treatment of the corrected data has led to more accurate kinetic results in degradation studies.

Computational study on the geometry optimization and excited - state properties of riboflavin by ArgusLab 4.0.1.

Riboflavin (vitamin B2) belongs to a group of respiratory enzymes that occur widely in animals and plants participating in vital oxidation- reduction processes in the body. A computational study was conducted on riboflavin by ArgusLab 4.0.1 to obtain the most active conformation of riboflavin and to analyze its excited-state properties. The best conformation of riboflavin was found to be -199.2173 kcal/mol which is the minimum potential energy calculated by geometry convergence function by ArgusLab software; performed according to Hartree-Fock calculation method. Electronic transition states (ground and excited), were also calculated and visualized by semi-empirical ZINDO method by ArgusLab from which molecular properties such as energies, wave function and dipole moments were established. All the results obtained from geometry optimization and excited-state properties lead us to delineate the active sites with charged groups of riboflavin to interact with the receptors. Such types of investigations are significant for drug-receptor interactions.