Immobilization of pneumococcal polysaccharide vaccine on silicon oxide wafer for an acoustical biosensor.

One the most important aspects of a biosensor is related to immobilization and maintenance of specific reference compounds on sensing surfaces. A method for the immobilization of polysaccharides to a silicon oxide surface intended for Surface Acoustical Waves (SAW) sensors is described. Silicon oxide is a hydrophobic inorganic support used for the fabrication of many electronic devices. The pneumococcal polysaccharide (PPS) vaccine is immobilized via Protein A after pre-treatment of the surface with hydrochloric acid. The effects of non-specific binding are discussed. The results indicate that the immobilization of PPS via Protein A increases the sensitivity of detecting Streptococcus pneumoniae antibodies in human sera and offers greater reproducibility of response compared with ELISA methods. The principles of this technique are simple and are applicable to the immobilization of many capsular polysaccharides.

[Diffusion of ceftriaxone into the human brain]. / Diffusion de la ceftriaxone dans le cerveau humain.

Study of the penetration of ceftriaxone into the brain of patients who underwent surgery for cerebral tumors. Seventeen patients received 2 g of ceftriaxone intravenously 2 h to 13 h before blood and brain samples were taken. Ceftriaxone levels in serum and in non tumoral cerebral tissue were determined by the agar well diffusion technique. Hemoglobin concentration was measured in cerebral samples in order to subtract ceftriaxone due to blood contamination. True ceftriaxone levels in cerebral tissue ranged from 0.3 to 12 mcg/g, mean 1.63 mcg/g. The ceftriaxone level ratio in brain and serum was low, mean about 2%, but cerebral ceftriaxone concentrations would be sufficient to inhibit more than 75% of bacteria isolated in recent cerebral abscesses. These results allow to do further therapeutic studies of ceftriaxone in cerebral abscesses due to identified and susceptible bacteria or in random treatment in association with antibiotics directed on anaerobic organisms and resistant hospital strains.