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Purpose: To investigate whether permeation enhancement techniques affect the nail plate. Methods: Infrared and impedance spectroscopies examined the effects of hydration, iontophoresis and N-acetyl-L-cysteine on the human nail. Results: While significant shifts to higher wavenumbers were observed for the symmetric and asymmetric -CH2 stretching vibrations these changes were essentially the same for the three treatments suggesting they were principally due to hydration alone. Spectral changes associated with amide bonds from nail protein were particularly evident post-treatment with N-acetyl-L-cysteine. The alternating current conductivity and permittivity of the nail, particularly at low frequencies, increased with hydration. Iontophoresis increased the low frequency ac conductivity of the nail but had less effect on the nail capacitance/permittivity. Further, the effects seemed to return gradually to baseline after termination of current passage. Treatment with N-acetyl-Lcysteine produced a greater perturbation, leading to increased low-frequency conductivity and a shift of the frequency-dependent conductivity region to a higher frequency. Conclusions: Overall, the effects of iontophoresis on infrared and impedance spectroscopic profiles of the nail were attributable simply to increased hydration and similar to those observed after skin iontophoresis. In contrast, both spectroscopy techniques indicated that N-acetyl-L-cysteine disrupted nail structure in line with the enhancer's known effect on keratin. [ABSTRACT FROM AUTHOR]

Abstract: The interactions of a number of commercially available dextran preparations with the lectin Concanavalin A (ConA) have been investigated. Dextrans over the molecular mass range 6×103–2×106 gmol−1 were initially characterised in terms of their branching and hence terminal ligand density, using NMR. This showed a range of branching ratios between 3% and 5%, but no clear correlation with molecular mass. The bio-specific interaction of these materials with ConA was investigated using microcalorimetry. The data obtained were interpreted using a number of possible binding models reflecting the known structure of both dextran and the lectin. The results of this analysis suggest that the interaction is most appropriately described in terms of a two-site model. This offers the best compromise for the observed relationship between data and model predictions and the number of parameters used based on the chi-squared values obtained from a nonlinear least-squares fitting procedure. A two-site model is also supported by analysis of the respective sizes of the dextrans and the ConA tetramer. Using this model, the relationship between association constants, binding energy and molecular mass was determined. [Copyright &y& Elsevier]