RESUMO
The influence of aqueous halide solutions on collagen coatings was tested. The effects on resistance against indentation/penetration on adhesion forces were measured by atomic force microscopy (AFM) and the change of Young's modulus of the coating was derived. Comparative measurements over time were conducted with halide solutions of various concentrations. Physical properties of the mesh-like coating generally showed large variability. Starting with a compact set of physical properties, data disperse after minutes. A trend of increase in elasticity and permeability was found for all halide solutions. These changes were largest in NaI, displaying a logical trend with ion size. However a correlation with concentration was not measured. Adhesion properties were found to be independent of mechanical properties. The paper also presents practical experience for AFM measurements of soft tissue under liquids, particularly related to data evaluation. The weakening in physical strength found after exposure to halide solutions may be interpreted as widening of the network structure or change in the chemical properties in part of the collagen fibres (swelling). In order to design customized surface coatings at optimized conditions also for medical applications, halide solutions might be used as agents with little impact on the safety of patients.
RESUMO
BACKGROUND: Environmental oxidative stress changing the properties of the tear fluid can lead to keratoconjunctivitis sicca (dry eye syndrome). The aim of this study was to determine whether iodide iontophoresis influences the antioxidative capacity (ACW = water soluble antioxidative capacity) of the tear fluid, and to compare iodide iontophoresis with other balneotherapeutic measures. METHODS: This prospective study evaluated 92 patients in four groups. Twenty-four patients were treated with iodide iontophoresis, 24 with other balneotherapeutic methods. Twenty-five patients received iodide iontophoresis combined with other balneotherapeutic methods and 21 persons received no treatment (control). Unstimulated tear fluid, serum and urine were collected. ACW was determined photochemically in tear fluid and serum; iodine was measured in urine photometrically. RESULTS: Iodide iontophoresis increases the ACW of the tear fluid but not the ACW of the serum. Other iodine therapies increase the ACW in serum but not in tear fluid. Iodine excretion in urine was increased in all treated groups compared to the control. CONCLUSION: The increase of ACW in tear fluid after iodide iontophoresis can support the defense mechanism of the eye against oxidative influence effects, which may alleviate the symptoms of keratoconjunctivitis sicca.
