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The newly proposed 15- and 24-loci mycobacterial interspersed repetitive unit (MIRU)-variable-number tandem repeat (VNTR) typing method was evaluated for its ability to differentiate 181 Mycobacterium tuberculosis Beijing family strains. Compared with the original 12-loci MIRU-VNTR typing method, the 15-loci system dramatically improved the discriminatory power for Beijing strains; however, large clusters that could be further differentiated by IS6110 restriction fragment length polymorphism (RFLP) were still obtained. The clonal stability and allelic diversity of a total of 31 VNTR loci were evaluated. VNTRs 3232, 3820, and 4120 were identified as the effective hypervariable VNTR set for the second-line typing of clustered strains following the 15-loci based scheme. Consequently, the discriminatory power of the new scheme (18 loci) equaled that of IS6110 RFLP.

The adlayer formation and adsorption kinetics of third- and fourth-generation (G3 and G4) amphiphilic surface-block dendrimers with amino and n-hexyl terminals (amino/hexyl), hydroxyl and n-hexyl terminals (hydroxyl/hexyl), and N-acetyl-d-glucosamine and n-hexyl terminals (glucosamine/hexyl) on solid substrates were investigated using atomic force microscopy, contact angle, surface plasmon resonance spectroscopy, and surface-enhanced infrared absorption spectroscopy. The amino/hexyl and hydroxyl/hexyl dendrimers formed dimer-unit layers on a solid surface, but the whole adlayer of the glucosamine/hexyl dendrimers displayed a rather flat surface, while the adlayer surface of each dendrimer was always hydrophilic. The time dependence of the adlayer formation, which was monitored in situ, obeyed two-step adsorption kinetics, namely, fast and slow adsorption steps. The adsorption amount at the adsorption equilibrium decreased in the order of hydroxyl/hexyl > amino/hexyl > glucosamine/hexyl dendrimers, and the adsorption amount of the third-generation species was greater than that of the fourth-generation species. The linear dependence of the whole adlayer thickness on the concentration of hydroxyl/hexyl dendrimers was obtained at the equilibrium state. The molecular orientation of the hexyl chains in the adlayers was in the order of amino/hexyl > hydroxyl/hexyl > glucosamine/hexyl dendrimers.

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