Background and purpose:Regulation of MMR activity under hypoxia may play an important role in genetic instability of cancer,but the mechanism is still unclear.We investigated the expression of DNA mismatch repair genes MLH1 and MSH2 in human SCLC cell line H446 under hypoxic condition and explore the role of promoter methylation of genes in hypoxia.Methods:RT-PCR and Western blot were applied to detect MLH1 and MSH2 expression in human SCLC cell line H446 at the mRNA and the protein level,respectively,under either hypoxic condition or after 5-Aza-CdR treatment.Meanwhile,methylation-specific PCR(MSP)was used to determine promoter methylation of MLH1 and MSH2.Results:The expression of MLH1 and MSH2 in H446 cells significantly decreased both at the mRNA and the protein level under hypoxic condition.5-Aza-CdR treatment led to the restoration of MLH1 and MSH2 expression,while,both MLH1 and MSH2 were down-regulated again after removing 5-Aza-CdR.Conclusions:The promoter methylation of MLH1 and MSH2 may play an important role in its defective expression in H446 cells under hypoxic condition.And 5-Aza-CdR could restore MLH1 and MSH2 expression.

Objective To explore the role of plasmids in inducing drug-resistance in Neisseria gonor-rhoeae.Methods The change of drug-susceptibility in Neisseria gonorrhoeae was compared before and after experiments of resistant plasmids conjugation,transformation and deleting.Results The drug-resistance was transferred from resistant strains to sensitive strains through the conjugation and transformation of resistant plasmids,while the drug susceptibility could be recovered through deleting such plasmids from resistant strains.Conclusion The plasmids play an important role in the development of drug-resistance in Neisseria gonorrhoeae.

Objective To study the expression of a new drug resistance-related gene cDNA fragment from human lung adenocarcinoma cell line in several types of lung cancer and their adjacent normal tissues. Methods The in situ hybridization histochemistry (ISHH) and Northern blot were employed to study the location and expression of the cDNA fragment in lung cancer cells. Results The results of ISHH and Northern blot showed that the expression of the fragment was discovered in 6 cases of 12 patients with lung adenocarcinoma, but not observed in the lung cancer tissues of other types and normal tissues(P

Homogenous fat extract was injected through the femoral vein to induce respiratory distress syndrome in 15 dogs. It was found that the changes of blood gases, chest x-ray films, and lung pathology of the dogs were similar to those of adult respiratory distress syndrome.The pathogenesis was extensive pulmonary fat embolism with complement activation and free radicals formation. Vitamin E was consumed during antiperoxidation. It is believed that this model serves better for the study of respiratory distress syndrome.

The therapeutic effects of prostaglandin E1 on respiratory distress syndrome induced with homogeneous fat extraction were observed in dogs.It was found that prostaglandin E1 could alleviate hypoxemia,reduce pulmonary capillary permeability,and attenuste pulmonary edema.The mechanism of the therapeutic efficiency of prostaglandin E1 on pulmonary damages is that prostaglandin E1 can inhibit the adherence of polymorphonuclear netttrophils and the genesis of oxygen free radicals,and protect the pneumocyte type Ⅱ.

Objective To explore the changes of multifocal electroretinogram (mERG) before and after retinal detachment surgery and its clinical significance. Methods Eighteen patients suffered from rhegmatogenous retinal detachment underwent mERG before and after surgery using VERIS Science TM 4.0. The mERG at different area was compared between preoperative and postoperative surgery. Results Preoperatively, the latencies of a wave and b wave in detached area were statistically longer than in attached area ( t =4.541 and 6.784, P

Objective　To clone the partial positive regulatory fragment of Na+/H+ exchanger-1 (NHE-1) gene from human lung cancer cells. Methods　After BamHⅠ and EcoRⅠ cut sites were added to the 5' ends of the upstream and downstream primers respectively, the partial positive regulatory sequence of NHE-1 gene was cloned with the length of 170 bp from genomic DNA of lung cancer cell line A549 cells with PCR method. The cloned fragment was ligated to plasmid pUC18. Finally, the constructed recombinant was identified with enzyme cut, PCR and DNA sequencing. Results　The cloned fragment was about 170 bp in size and successfully ligated to pUC18 with identifiation of double enzyme cut and PCR. DNA sequencing approved that the fragment cloned was objective one with 168 bp in length. Compared with the reported sequence, two t were lost. Conclusion　The positive regulatory fragment of NHE-1 gene from human lung cancer cells was successfully cloned.

Objective: To design and confirm the cleavage activity of ribozyme Rz217 to oncogene ki-rasG12V messenger RNA and search for a new method for gene therapy targeting oncogene ki-ras. Methods: According to Symon' s principle,design an ribozyme specific for ki-rasc12v mRNA, both the constructs for transcription in vitro of ribozyme Rz217 and ki-ras exonl and the mammalian expression constructs of ribozyme Rz217 were constructed by DNA recombinant technique,ribozyme Rz217 and ki-ras exonl mRNA was obtained by transcription in vitro with T7 and SP6 RNA polymerase. Pancre atic carcinoma cell line PaTu8988 and human hepatocellular carcinomacell line BEL7404 were transfected with Rz217 mammalian expression constructs and the level of endogenous ki-rasG12V mRNA or ki-ras mRNA was determined by semiquantitative RT-PCR. Results: Not only in vitro but also in vivo, ribozyme Rz217 can cleave the mRNA of oncogene ki-ras (G12V) in site-specific manner and can not cleave the mRNA of wild-type ki-ras. Conclusion: Ribozyme Rz217 can cleave oncogene ki-rasc12v mRNA and the cleveage is specific for ki-rasG12V mRNA.

Objective To investigate the pathological mechanism of delayed endolymphatic hydrops(DEH) , and clarify the clinical value of endolymphatic space imaging after intratympanic injection of gadolinium in the diag_nosis of delayed endolymphatic hydrops .Methods Twenty -four hours after bilateral intratympanic injection of gadolinium ,the locations and severity of endolymphatic hydrops of all patients were evaluated by using three dimen_sional fluid-attenuated inversion recovery (3D -FLAIR) and three dimensional real inversionrecovery (3D -real IR) .ResuIts All patients had unilateral or bilateral endolymphatic hydrops .Among 9 ipsilateral DEH patients , only 1 (11 .1% ) patient was identified as mild endolymphatic hydrops and the rest (88 .9% ) examined had signifi_cant endolymphatic hydrops in vestibule of their affected ears ;Endolymphatic hydrops appeared in cochlea of the af_fected ear in 8 (88 .9% ) patients ,except for 1 patient .Endolymphatic hydrops were not observed in the contralater_al ears of 9 ipsilateral DEH patients .Mild endolymphatic hydrops in bilateral vestibule ,severe in right cochlear and none in left cochlea of contralateral DEH patient were identified .ConcIusion Endolymphatic hydrops is the primary pathological factors of DEH .Endolymphatic space imaging after intratympanic injection of gadolinium can intuitively reflect the locations and severity of endolymphatic hydrops in DEH patients .

Objective To investigate the role of methylated DNA mismatch repair gene MLH1 and MSH2 in the acquired multidrug-resistance of human small cell lung cancer cells H446.Methods The reverse transcription polymerase chain reaction(RT-PCR)and Western blot were applied to measure MLH1 and MSH2 mRNA and protein expressions of the multidrug-resistant cells H446/DDP and its parental cells H446.The promoter methylation status of the genes was assessed by methylation-specific PCR(MSP).Results The expressions of MLH1 and MSH2 significantly decreased both in mRNA level and protein level.Promoter methylation of MLH1 was observed in H446/DDP cells but not in H446 cells.Promoter semi-methylation of MSH2 in H446 cells was transformed to methylation in H446/DDP cells.Conclusion The downregulation of DNA mismatch repair gene MLH1 and MSH2 induced by its promoter methylation may play an important role in the acquired multidrug resistance of human small cell lung cancer.