Objective:To investigate the effect of the ceramometal b ridge on the local gingival groove flora.Methods: Classi cal bacterial incubation and identification were used to study the changes of th e local gingival groove flora in 6 patients wearing ceramometal bridge for 1 wee k to 3 months. Results: 3 months after the prosthetic procedure the CFU o f P.melaninogenica, Gram-positive bacilli cmainly Actinomyces and the t otal bacteria were significantly increased (P

Objective To investigate the cell-type-specific enhancer (CTSE) in HPV16 and its variation in cervical carcinoma. Methods CTSEs were detected by polymerase chain reaction (PCR) in 58 cervical carcinoma from Shaanxi province; in addition variation of CTSEs was analyzed through single-strand conformation polymorphisms (SSCP). Results HPV16 CTSEs were detectable in 34 of 58 (57%) specimens and mutant rate was 41%(14/34) and the main mutations of chosen randomly variant CTSE (CTSEv) happened at YY1 binding sites in addition to glucocoticoid response elements (GRE). Conclusion CTSE in some specimens of Shaanxi province was obviously different from that in HPV16 wild type and variant CTSE might affect the transcriptional regulation of LCR on viral P97, which regulates over-expression of viral oncogenes in cervical carcinoma.

Objective To clone and express the ns5a gene of hepatitis C virus(HCV) 1b strain DY.Methods By using the prokaryotic cell gene engineering,HCV ns5a gene was amplified with nested PCR from the plasmid HCV17 of HCV 1b strain DY full-length gene and inserted into the cloning pMD18-T vector.The cloned HCV ns5a gene was separated and subcloned into expression vector pET-28a and induced by IPTG in E.coli.BL21.The expressed product was identified by SDS-PAGE and Western-blot methods.Results Recombinant expression plasmid pet-28a-ns5a was constructed and expressed successfully.Conclusion HCV ns5a gene was cloned and expressed.This might be helpful for further studies on the nature and biological properties of the ns5a gene.

BACKGROUNDTo explore the feasibility of cloning of the hepatocyte receptor interacting with the Pre S1 protein of HBV by two hybrid system.

METHODSYeast expression plasmids encoding fusion proteins of full length or portions of Pre S1 of HBV and DNA binding domain of yeast protein GAL4 were constructed and used to transform yeast reporter strain SFY526. Reporter gene product ?galactosidase activity was assayed as a measure of transcription activation in yeast. Mammalian expression plasmid encoding fusion proteins of full length Pre S1 and DNA binding domain of GAL4 was constructed and used to cotransfect hepatoma cell line Huh?7 together with CAT reporter plasmid. Cell extracts were assayed for CAT activity by thin?layer chromatography.

RESULTSThe fusion proteins of full length Pre S1 protein and GAL4 DNA binding domain present transcriptional activation function in yeast. The transcription activating sequence is localized to the 21 to 47 amino acids of Pre S1 protein Fusion proteins of full length Pre S 1 and GAL 4 DNA binding domain do not show transcriptional activation function in mammalian cells.

CONCLUSIONThe transcriptional activating sequence of HBVPre S1 protein in yeast overlaps the hepatocyte receptor binding site. The transcriptional activation function of HBV Pre S1 protein in yeast may prevent researchers?from using yeast two hybrid system to clone HBV receptor interacting with Pre S1 protein. However, the Pre S1 protein does not show transcriptional activation function in mammalian cells. Mammalian two?hybrid system may be a practical method to clone the HBV hepatocyte receptor interacting with Pre S1 protein.

DNA-Binding Proteins ; genetics ; Fungal Proteins ; genetics ; Hepatitis B Surface Antigens ; genetics ; Humans ; Protein Precursors ; genetics ; Recombinant Fusion Proteins ; genetics ; Transcriptional Activation ; Tumor Cells, Cultured ; Yeasts