ABSTRACT
Although most microbes are not readily cultured in the lab, microbial DNA can be extracted directly from an environmental sample and be functionally expressed in a suitable host for natural products discovery, and this approach has been termed "metagenomics". An E'mei Mountain soil metagenomic library was constructed using an Escherichia coli-Streptomyces shuttle vector for functional based screening of anti-bacterial clones in Streptomyces albus host. Two active clones were obtained and their fermentation broths were studied for the inhibitory effect on Staphylococcus aureus biofilm. Their fermentation products have a good inhibitory effect on the formation of S. aureus biofilm, and the inhibitory effect could exceed 90% when the concentration of sample was 2 MIC (Minimum Inhibitory Concentration). In addition, two samples had significantly effect on S. aureus biofilm dispersal, and the clearance rate of EM110 was higher than EM123. In conclusion, substances with strong bioactivities on biofilm formation and dispersal of S. aureus could be discovered by using metagenomics technology.
ABSTRACT
Objective To analyze the MR manifestations of the focal nodular hyperplasia (FNH)in liver and observe the MRI changes after 30-36 months.Methods 12 (14 lesions)of the 13 patients (1 5 lesions)were firstly diagnosed as FNH by MRI with plain scan and dynamic Gd-DTPA enhancement,and then were confirmed by the follow-up survey with similar MRI after 30 - 36 months.The last one patient was also scanned with Gd-EOB-DTPA enhancement but with similar plain scans.The size,signal,en-hancement patterns of the lesions were analyzed and compared with those in the follow-up survey.Results Typical MR manifesta-tions were found in 93.33%(14/1 5)of the lesions with hypo-or iso-intensity on T1 WI,hyper-or iso-intensity on T2 WI,marked en-hancement in arterial phase and attenuation but still equal to or higher than normal liver parenchyma in portal and delayed phases af-ter Gd-DTPA administration.In addition,the central scar showed hypointensity on T1 WI,hyperintensity on T2 WI,and enhance-ment in delayed phase.The enhanced small vessels inside lesions and the pesudocapsule enhancement could be seen in delayed phase. The only one lesion with Gd-EOB-DTPA enhancement showed marked enhancement in arterial and portal phases,and slight hyperin-tensity in hepatocellular phase with hypo-intense central scar in any phases.As for the only one lesion with atypical manifestation,it showed isointensity on T1 WI,slightly hyperintensity on T2 WI,nonenhancement in arterial phase,slightly enhancement in portal phase,and small vascular enhancement inside the lesion in delayed phase.After the follow-up survey of 30-36 months 92.86%(13/14)lesions did not change,however one lesion (10mm)disappeared.Conclusion Typical FNH shows similar MRI characteristics, iso-intense or slightly hypo-intense signal on T1 WI,iso-intense or slightly hyper-intense signal on T2 WI,marked enhancement in ar-terial phase,the central scar enhancement and the inside small vascular enhancement of lesions in delayed phase.It is valuable in dif-ferential diagnosis.