[In vitro evaluation of the antibacterial activity of nemonoxacin against Mycobacterium tuberculosis, Mycobacterium intracellulare and Mycobacterium abscessus].

Objective: To test the in vitro antibacterial activity of nemonoxacin against clinically isolates of Mycobacterium tuberculosis complex(MTBC), Mycobacterium intracellulare(MI) and Mycobacterium abscessus(MA). Methods: Totally 128, 80 and 50 isolates of MTBC, M.intracellulare and M.abscessus were tested, respectively. The minimum inhibitory concentrations (MICs) of nemonoxacin and levofloxacin against the strains of the three most frequently isolated mycobacterium species were measured by double dilution method with micro-well plate. Results: The MICs of 104(81.2%) strains of MTBC isolates against levofloxacin were ≤ 1 µg/ml. Whereas 112 (87.5%) strains of MTBC isolates had MICs against nemonoxacin than>1 µg/ml, furthermore, the MICs of 88(68.8%)strains of MTBC isolates against nemonoxacin were≥4 µg/ml. The median MIC of M. intracellulare isolates against levofloxacin and nenofloxacin were 16 and 32 µg/ml, separately, while were 16 µg/ml and 8 µg/ml for M. abscessus, respectively. The ratios of nemonoxacin MIC/levofloxacin MIC of M. abscessus were between 0.125-1.000. Conclusions: Nemonoxacin presented weaker inhibitory activity than levofloxacin against M. tuberculosis, whereas it had better activity than levofloxacin against M. abscessus.

[Discriminatory power of variable number on tandem repeats loci for genotyping Mycobacterium tuberculosis strains in China].

Objective: Using the standard genotype method, variable number of tandem repeats (VNTR), we constructed a VNTR database to cover all provinces and proposed a set of optimized VNTR loci combinations for each province, in order to improve the preventive and control programs on tuberculosis, in China. Methods: A total of 15 loci VNTR was used to analyze 4 116 Mycobacterium tuberculosis strains, isolated from national survey of Drug Resistant Tuberculosis, in 2007. Hunter-Gaston Index (HGI) was also used to analyze the discriminatory power of each VNTR site. A set combination of 12-VNTR, 10-VNTR, 8-VNTR and 5-VNTR was respectively constructed for each province, based on 1) epidemic characteristics of M. tuberculosis lineages in China, with high discriminatory power and genetic stability. Results: Through the completed 15 loci VNTR patterns of 3 966 strains under 96.36% (3 966/4 116) coverage, we found seven high HGI loci (including QUB11b and MIRU26) as well as low stable loci (including QUB26, MIRU16, Mtub21 and QUB11b) in several areas. In all the 31 provinces, we found an optimization VNTR combination as 10-VNTR loci in Inner Mongolia, Chongqing and Heilongjiang, but with 8-VNTR combination shared in other provinces. Conclusions: It is necessary to not only use the VNTR database for tracing the source of infection and cluster of M. tuberculosis in the nation but also using the set of optimized VNTR combinations in monitoring those local epidemics and M. tuberculosis (genetics in local) population.

[Effects of panaxadiol saponins isolated from Panax notoginseng on intracellular and extracellular calcium].

Panaxadiol saponins (PDS) contain saponins Panax notoginseng B1 and E. The spontaneous beating induced by isoproterenol in isolated rat right atria and the increase of contractile force induced by Ca2+ in isolated guinea pig colon were inhibited by PDS 75 and 150 micrograms.ml-1, respectively and perhexiline 6.25 and 12.5 mumol.L-1, respectively. It suggested that PDS could block the potential-dependent and receptor-operated calcium channel in smooth muscle. PDS 150 micrograms.ml-1 and perhexiline 6.25 mumol.L-1 depressed the contractile force induced by norepinephrine and Ca2+ in isolated rat aortic strips in Ca(2+)-free Krebs' solution. It suggested that PDS and perhexiline not only inhibited the release of intracellular Ca2+ but also blocked the inflow of extracellular Ca2+.