[A colorimetric method for vascular endothelial growth factor detection based on aptamer and magnetic beads].

Objective: To develop a novel colorimetric method for detecting the tumor biomarker vascular endothelial growth factor (VEGF) based on aptamer and magnetic beads.

Methods: The capture aptamer was hybridized to urease functionalized single-stranded DNA (ssDNA) and immobilize on the surface of magnetic beads by specific biotin-avidin binding. In the presence of VEGF, aptamers bound to VEGF to form a specific stem-loop structure to release the urease functionalized ssDNA.

[Effects of short-term VDT usage on visual functions].

Objective: To evaluate the effects of short-term VDT usage on visual functions.

Methods: Visual function of the video display terminal (VDT) operators before and after 1 hour VDT usage were assessed. These included refraction, amplitude of accommodation, near point of convergence, AC/A, phorias, fusional convergence and divergence, tear film break time (BUT) and aberrations.