Improved method for tuberculocidal and mycobactericidal activity testing of disinfectants based on the European Standard EN 14348.

Safe measurements to prevent the transmission of (multidrug-resistant) mycobacteria such as disinfection are essential in healthcare settings. In Europe chemical disinfectants are tested for their tuberculocidal and mycobactericidal efficacy by the internationally accepted test procedure described in EN 14348. However, especially for amine-based disinfectants, invalid results may occur by this procedure due to insufficient neutralization. In this multi-laboratory study the procedure described in EN 14348 was optimized by a combination of chemical neutralization and membrane filtration in order to obtain a valid and secure method especially for amine-based disinfectants.

A novel GTP-binding protein which is selectively repressed in SV40 transformed fibroblasts.

We have used a subtractive hybridization procedure to isolate cDNA clones for proteins that are produced by human fibroblasts, but not by their SV40-transformed counterparts. With this technique we found, in addition to fibronectin and collagen VI, a novel GTP-binding protein. Sequencing of overlapping cDNA clones demonstrated that this protein is composed of 364 amino acids with a molecular mass of 41 kDa and a calculated isoelectric point of 9.4. It contains the five sequence motifs G1-G5 that are conserved in all GTP-binding proteins. Apart from these characteristic motifs the amino acid sequence differs substantially from those of the well characterized G-proteins, but it is similar to those of some recently identified proteins from Caenorhabditis elegans, from Schizosaccharomyces pombe, and from an archaebacterium, suggesting the existence of a new subfamily within the superfamily of the GTP-binding proteins. The striking conservation of the primary structure between distantly related species indicates a fundamental function of the new protein. Since it is produced in normal, but not in virally transformed fibroblasts, it may play a role in the expression of the transformed phenotype or in growth control.