AIM To select a test method for specifical, sensitive and rapid identification of LT+ E. coli.METHODS Stool samples inoculated into LB solution were cultured for 4 hours at 35℃. 10 μ boiled culturesolution was taken to template. Two oligonucleotide primers were used in a polymerase chain reaction (PCR)procedure to amplify a highly conserved DNA sequence of the A subunit of the heat-labile enterotoxin.Detection of the 110 bp amplified product can be done by agarose gel electrophoresis. Thirty strains ofknown bacteria (LT+ E. coli (EC-129), ST+ E. coli (EC-130)and LT+ ST+ E. coli (EC-142), Salmonellatyphimurium , Salmonella typhi , Salmonella paratyphi A, Salmonella group C, Shigella sonnei , Enterobacteraerogenes, Alcaligenes sp, Providencia rettgeri, Proteus mirabilis, Morganella morganii, Pseudomouasaeruginosa, Aeromonas hydrophila, Klebsiella pneumoniae, Citrobacter diversus, Enterobacter cloacae, 12strains of E. coli isolated from bile samples ) and 108 diarrhea samples were detected. A total of 108 diarrheasamples were compared with LT probe hybridization, modified Eleck (M-Eleck) and ELISA simultaneously.RESULTS By PCR, of the 30 strains of bacteria, only LT+ E. coli and LT+ ST+ E. coli were positive; in40 of the 108 diarrhea samples, 20 were positive and in the other 68 samples from infants, only five werefound to be positive. Of the 25 positive samples by PCR, 23 were also found to be positive in the other 3tests; 1 was found to be positive by M-Eleck and ELISA. Of the 83 negative samples by PCR, the samenegative results were found by M-EIeck and ELISA, but 2 were found to be positive by LT probehybridization. The overall coincidence rate was about 95%. Analysis of correlation showed a significantdifference between PCR and other three tests (P<0.01) and analysis of difference showed no significantdifference (P>0.05) between them. In the detection of LT+ E. coli by means of PCR, the minimumnumber of target bacteria required was 50 CFU. The whole test was finished in 7 hours.CONCLUSION Detection of LT+ E. coli by PCR showed that the method is specific, sensitive and rapid.

AIM To evaluate the clinical value of creatine kinase macroisoenzyme type 2 (CK-M2) and oligosaccharideprotein (OP) in serum from patients with gastric carcinoma (GC).METHODS Serum level of CK-M2 was detected by agar gel electrophoresis. OP concentration was measuredby an enzyme immunoassay.RESULTS Serum levels of CK-M2 and OP in 57 cases of GC were significantly higher than those in 51 caseswith gastric precancerous lesion and 28 controls. The diagnostic sensitivity and specificity for GC with CK-M2 was 56.10% and 98.63% respectively. CK-M2 and OP were not associated with histologic type and degreeof differentiation.CONCLUSION These results suggest that CK-M2 may serve as a marker to diagnose GC, and the specificityis higher, whereas OP is not more significant for GC diagnosis, but it could be a useful indicator forevaluation the status of body immune.