Effects of vitamin A on retinal pigment epithelial cells in vitro

Human retinal pigment epithelial (RPE) cell monolayers were used in an in vitro wound-healing experiment. Wound closure were studied over time in the presence of various concentrations of all-trans retinol (vitamin A). It was found that 5-20 micrograms/ml (17.5-70 mumol/l) of vitamin A significantly inhibited wound closure by inhibiting cell migration and proliferation. In a collagen gel-contraction model, similar doses of vitamin A partially inhibited cell contractility. Cellular morphology, as assessed by phase-contrast microscopy, changed from a regular polygonal shape to an elongated stellate shape. Indirect immunofluorescence patterns of fibronectin, actin, tubulin, and vimentin were altered after exposure to vitamin A. All these effects were reversible after removal of the drug from the medium. Modulation of RPE growth and cell-mediated contraction may be useful in the treatment of ocular proliferative diseases.

Protection of health care workers against bloodborne infections in emergency departments

Health care workers in emergency departments are at particular high risk for acquiring occupational bloodborne infections. Needle stick injuries are the main hazard. Systematic HIV testing of patients admitted to emergency department is not a cost beneficial way to protect health care workers from acquiring such infections. Prevention strategies should be based on the adherence to universal precautions, hepatitis B vaccination, the utilization of safer devices and the training/education of health care workers.