Many recent bioanalytical systems based on immunologic and hybridization reactions in a mono- or bidimensional microarray format require technology that can produce arrays of spots containing biospecific molecules. Some microarray deposition instruments are commercially available, and other devices have been described in recent papers. We describe a system obtained by adapting a commercial ink-jet printer and used to produce mono- and bidimensional arrays of spots containing horseradish peroxidase on cellulose paper. In a few minutes, it was possible to obtain bidimensional arrays containing several thousands of spots with a diameter as low as 0.2 mm, with each of which requiring only a few nanoliters of the enzyme deposition solution. The quantity of enzyme in each spot was evaluated with a chemiluminescent reaction and a charge-coupled device-based, low-light imaging luminograph. The chemiluminescence measurements revealed that the reproducibility of the enzyme deposition was satisfactory for analytical purposes, with the variation coefficients being lower than 10% in almost all cases.

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Background: Computers and telephones are ubiquitous in the hospital and have been shown to be contaminated with potentially pathogenic microorganism. The aim of the study was to determine microbial contamination on computer keyboards and telephone handsets and the effectiveness of a disinfecting technique (DT). Methods:A matched cross-over study, involving an overall of 50 computer keyboards and 50 telephone handsets, was conducted in three hospitals, located in the Local Health Area of Siena (Italy) before and after the use of an innovative DT consisting of a malleable-elastic compound, containing ethanol, which adheres to surfaces, removes dirt and disinfects. Total bacterial count was evaluated and several types of bacteria and fungi were researched pre-and post-use of the DT. Non parametric tests: Wilcoxon signed rank and Mann Whitney, were used, when appropriate. Results:The DT was effective in disinfecting the objects. In fact, Colony-Forming Units (CFUs) decreased to zero in most comparisons. All the comparisons showed significant differences (p<0.001) after the DT, both for computer keyboards and telephone handsets. The only exception was found for molds in telephones (p=0.062). Keyboards emerged to be dirtier than telephones handsets (p<0.05) for several types of bacteria. Conclusions:The data suggest that microbial contamination of keyboards and telephones is considerable. These objects can be a vehicle for Health Care-Associated Infections HAIs and their disinfection should not be neglected. The DT showed to be appropriate for the disinfecting purpose.

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The antioxidant activity of a representative series of free, glycine- and taurine-conjugated bile acids was evaluated by two different chemiluminescent assays: (a) the enhanced chemiluminescence system based on horseradish peroxidase and luminol/oxidant/enhancer reagent, and (b) the hypoxanthine/xanthine oxidase/Fe(2+)-EDTA/luminol system. Bile acids were studied at final concentrations ranging from 1 to 28 mmol/L. All of the bile acids studied inhibited the steady-state chemiluminescent reaction and the extent of inhibition depended upon the structure of the bile acids, whereas the duration was related to bile acid concentration. The mechanism of the light inhibition is probably due to trapping of oxygen free radicals generated in the chemiluminescent reactions, within bile acid micelles. The free radicals trapped into micelles reduced the formation of luminol radicals and consequently the light output; when the micelles were saturated, the oxygen free radicals in solution again produced luminol radicals. The micelle interaction with reactive oxygen species could be a physiological mechanism of defence against the toxicity of those species in the intestinal content. On the other hand, alterations in bile acid organ distribution, concentration and composition leads to a membrane damage caused by their detergent-like properties, which could be associated to oxygen free radical production.