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Biomedical subjects

H Ren

Publications and source records attributed to H Ren.

At least 73 records · Page 4Linked to original sources
PubMed2000

Construction and analysis of cDNA library of Necator americanus third stage larvae.

OBJECTIVE: To obtain the genetic information on Necator americanus and to search for the purpose genes. METHODS: mRNA was isolated from the third stage larvae of Necator americanus maintained in hamsters. Double strand cDNA was synthesized and ligated to lambda ZAPII vector to construct the cDNA library. Expressed sequence tages (ESTs) were obtained by single pass sequencing of randomly isolated cDNA clones from the established library. RESULTS: A cDNA library of N. americanus was successfully constructed with high recombinant efficiency. The titer of unamplified library was 1 x 10(7). The insert size was about 750-3,000 bp. Of 11 ESTs obtained from the library, 7 have a significant homology with certain functional genes. CONCLUSION: A high quality and high representative cDNA library of N. americanus was constructed at the first time and some functional genes were identified from the library by ESTs.

Animals↗
PubMed2000

[The effects of sodium nitroprusside-induced hypotension at different levels on cerebral blood flow and metabolism: a clinical study].

OBJECTIVE: The clinical experiment was designed for observing the effects of deliberate hypotension at different level on cerebral blood flow and metabolism. METHODS: 30 ASA Grade I-II patients were randomly allocated to one of three groups (each group n = 10). Hypotension was induced by sodium nitroprusside in group 1[mean arterial pressure (MAP) = 55 mmHg] and group 2 (MAP = 65 mmHg). Group 3 (control) was on normotension. The changes of cerebral blood flow during hypotension were estimated according to the variability of cerebral blood flow velocity (CBFV) in the middle cerebral artery(MCA), which was obtained through transcranial Doppler ultrasonography (TCD). RESULTS: Hypotension caused a moderate decrease in CBFV, but no significant difference, in CBFV and oxygen saturation in internal jugular vein(SjO2), either among three groups or during the procedure. CONCLUSIONS: It is safe for cerebral perfusion and metabolism with deliberate hypotension at MAP = 55 mmHg.

Antihypertensive Agents↗
PubMed2000

Adenosquamous lung carcinoma: clinical characteristics, surgical treament and prognosis.

OBJECTIVE: The effectiveness of surgical resection of adenosquamous carcinoma of the lung remains poorly defined because of the histology's relatively low frequency, the failure in most published series to separate adenosquamous carcinoma from the other variants of non-small cell lung carcinoma. To define the effectiveness of treatment of adenosquamous carcinoma, we have retrospectively reviewed our hospital experience over a 12-year period. METHODS: Retrospectively reviewed 22 cases of adenosquamous carcinoma who were surgically treated, except one patient, in the PUMCH from Jan. 1985 to Aug. 1997. This series constitutes the 1.9% of a total of 1 245 patients with all types of surgical treatment for the primary lung cancer during the same time. RESULTS: The adenosquanous carcinoma was mostly presented in the old patients with a mean age of 60 years and mostly located in the peripheral of lung (n = 20). The overall 5-year survival was 23%. Those with stage I tumors survival was only 18% (n = 13), stage II 5%. The survival in stage III tumos was not longer than 25 months and in stage IV survival was not longer than 12 months. CONCLUSION: Our results suggest that adenosquamous carcinoma of lung was a virulent tumor, which exhibited highly aggressive biological behavior with early lymph nodes metastasis (46%) and its prognosis was worse than that of both squamous cell carcinoma and adenocarcinoma.

Adult↗
PubMed1999

A multiple-capillary electrophoresis system for small-scale DNA sequencing and analysis.

A five-capillary system has been developed for DNA sequencing and analysis. The post-column fluorescence detector is based on a sheath-flow cuvette. The instrument provides uniform and continuous illumination of the samples. The cuvette virtually eliminates cross-talk in the fluorescence signal between capillaries. Discrete single-photon counting avalanche photodiodes provide high efficiency light detection. The instrument has detection limits (3sigma) of 130 +/- 30 fluorescein molecules injected onto each capillary. Over 650 bases of sequence at 98.8% accuracy were generated in 100 min at 50 degrees C from M13mp18. Separation and detection of short tandem repeats proved efficient and accurate with the use of internal standards for direct comparison of migration times between capillaries.

Adult↗
PubMed1999

Oxidation of the alpha(3)(betaD311C/R333C)(3)gamma subcomplex of the thermophilic Bacillus PS3 F(1)-ATPase indicates that only two beta subunits can exist in the closed conformation simultaneously.

In the crystal structure of the bovine heart mitochondrial F(1)-ATPase (Abrahams, J. P., Leslie, A. G. W., Lutter, R., and Walker, J. E. (1994) Nature 370, 621-628), the two liganded beta subunits, one with MgAMP-PNP bound to the catalytic site (beta(T)) and the other with MgADP bound (beta(D)) have closed conformations. The empty beta subunit (beta(E)) has an open conformation. In beta(T) and beta(D), the distance between the carboxylate of beta-Asp(315) and the guanidinium of beta-Arg(337) is 3.0-4.0 A. These side chains are at least 10 A apart in beta(E). The alpha(3)(betaD311C/R333C)(3)gamma subcomplex of TF(1) with the corresponding residues substituted with cysteine has very low ATPase activity unless it is reduced prior to assay or assayed in the presence of dithiothreitol. The reduced subcomplex hydrolyzes ATP at 50% the rate of wild-type and is rapidly inactivated by oxidation by CuCl(2) with or without magnesium nucleotides bound to catalytic sites. Titration of the subcomplex with iodo[(14)C]acetamide after prolonged treatment with CuCl(2) in the presence or absence of 1 mM MgADP revealed nearly two free sulfhydryl groups/mol of enzyme. Therefore, one pair of introduced cysteines is located on a beta subunit that exists in the open or partially open conformation even when catalytic sites are saturated with MgADP. Since V(max) of ATP hydrolysis is attained when three catalytic sites of F(1) are saturated, the catalytic site that binds ATP must be closing as the catalytic site that releases products is opening.

Adenosine Triphosphate↗
PubMed1999

[Production of HBV surface antigen-specific target cell].

OBJECTIVE: To analyze the hepatitis B virus surface antigen (HBsAg)-specific cytotoxic T-cell (CTL) response during hepatitis development and investigate the effect of some factors on CTL response. METHODS: The recombinant retrovirus plasmid PLXSN-S was tranferred into PA317 by electroporation and the pseudoviruses produced from PA317 were used to infect EL4. Clones which highly expressed HBsAg were selected with limited dilution. RESULTS: A clone expressing-HBsAg the highest (A = 0.85 in supernatant at 48th hour) was obtained which steadly expressed HBsAg in vitro after at least 100 passages. It worked very well when used as target cells in CTL response after C57 mice immunized with PLXSN-S and recombinant adenovirus vector (rAdv-B7-2-S). CONCLUSION: We constructed HBsAg-specific target cell line which steadly expressed HBsAg. It may play an important role in HBsAg CTL response and immunopathogenetic mechanisms of hepatitis B.

Animals↗
PubMed1999

Separating DNA sequencing fragments without a sieving matrix.

The possibility of separating appropriately labeled DNA fragments using free-flow capillary electrophoresis was predicted a few years ago based on simple theoretical arguments. Free-flow separation of double-stranded DNA (dsDNA) fragments in the 100-1000 base range was later demonstrated using a streptavidin label. In this article, we now report that end-labeled free-flow electrophoresis (ELFSE) can also be used to sequence single-stranded DNA (ssDNA). The first 100 bases of a DNA sequencing reaction were read without any sieving matrix when fractionated streptavidin was added to the 5'-end of the ssDNA fragments. These separations required only 18 min and did not require coated capillaries. An analysis of the results indicates that sample injection, analyte-wall interactions and thermal diffusion are the limiting factors at this time. Extrapolating from our data, we predict that several hundred bases could be sequenced in less than 30 min with the proper conditions. ELFSE thus offers an attractive potential alternative to polymer solutions for DNA sequencing in capillaries and microchips.

Buffers↗
PubMed1999

Role of Helicobacter pylori infection in pathogenesis of gastric adenocarcinoma.

To study the effect of Helicobacter Pylori (Hp) on the process of gastric carcinogenesis, 35 cases of chronic gastritis, 20 cases of gastric adenocarcinoma were studied by use of transmission electron microscopy, immunohistochemical and molecular biological technique. The results showed that 24 of 35 cases of chronic gastritis were positive for Hp, 11/20 cases of gastric adenocarcinoma were Hp positive. PCNA positive cell labeling index (LI) in Hp-associated chronic gastritis (LI = 20.6 +/- 4.7) was higher than that in Hp negative chronic gastritis (LI = 11.3 +/- 5.2) (P < 0.05). HSP70 expression of gastric adenocarcinoma tissues in Hp-infected patients were lower than that of non-Hp-infected gastric cancer. p53 gene mutation was found in gastric adenocarcinoma with positive Hp. It was suggested that Hp may enhance gastric cell proliferation, decrease the expression of HSP70 which induces p53 mutation.

Adenocarcinoma↗
PubMed1999

Thoracoscopic procedure for intrathoracic diseases: current status in mainland China.

One hundred and five patients underwent a procedure of video-assisted thoracoscopic surgery (VATS) during a period of 5 years, in the Department of Cardiothoracic Surgery, Peking Union Medical College Hospital, Beijing, China. Among them, there were 36 cases suffering from spontaneous pneumothorax, 24 having a nodule of the lung, nine intrathoracic multiple nodules, 10 undefined pleural effusions, eight mediastinal mass, 15 interstitial fibrosis, two pericardial effusion, and one severe emphysema. In all patients of this series, the diagnosis was demonstrated and the suitable management was performed.

China↗
PubMed1999

Stanniocalcin 2: characterization of the protein and its localization to human pancreatic alpha cells.

Stanniocalcin (STC) is a hormone that was originally identified in fish, where it inhibits calcium uptake by the gills and gut and stimulates phosphate adsorption by the kidney. Recently, two mammalian homologues of stanniocalcin were identified. The first (STC1) shows 61% identity to the fish stanniocalcins and appears to have a function similar to that of the fish stanniocalcins. The second homologue (STC2) is 30-38% identical to the fish stanniocalcins, and is characterized by unique cysteine and histidine motifs that are not found in the other stanniocalcins. We purified both the native hamster and recombinant human STC2 proteins and obtained a partial amino acid sequence of the hamster protein. Both proteins behave as a disulfide bonded homodimer, which undergoes post-translational modification(s). The STC2 gene was localized to human chromosome 5q35. Northern blot analysis revealed that the primary site of human STC2 production is the pancreas, and immunostaining localized the STC2 protein to a subpopulation of cells in the islet. Double immunostaining for STC2 and either insulin or glucagon revealed that STC2 protein is found in the alpha cells, but not the beta cells. We speculate that STC2 may play a role in glucose homeostasis.

Amino Acid Sequence↗
PubMed1999

Dexamethasone stimulates human A1 adenosine receptor (A1AR) gene expression through multiple regulatory sites in promoter B.

The expression of the human A1 adenosine receptor gene is controlled by two promoters, promoters A and B, and they are located 600 base pairs apart. The characteristics of the two promoters differ by the activity of expression, tissue specificity, and the potential regulatory elements around them. Promoter A is more active but its expression is observed only in selected tissues, whereas promoter B is constitutively expressed but at much reduced levels. In Chinese hamster ovary (CHO) cells transiently transfected with plasmids containing either promoter linked to a reporter gene, dexamethasone (dex) can stimulate (or enhance) the expression of promoter B much more effectively than that of promoter A. Mutation and deletion studies on plasmids containing promoter B have shown that the stimulation is mediated through multiple regulatory sites, including a serum response element, AP1, and TATA box. However, a single-glucocorticoid response element monomer-binding site between promoters A and B does not have significant contribution to dex-regulated expression. The interactions between glucocorticoid receptor (GR) and some regulatory sites are probably occurring via this protein (GR) interacting with other DNA-binding proteins because there is no GR DNA-binding sequence in the sites studied. The stimulation can be eliminated by mifepristone, an antagonist of GR, indicating the involvement of GR in gene regulation. In addition, dex treatment also stimulated the expression of A1 adenosine receptors in CHO cells transfected with the plasmids containing contiguous genomic sequences of promoter B or promoters A and B linked to the receptor-coding sequence. When promoter A is active and both promoter A and B are present in a construct, dex treatment induced a much smaller percentage of stimulation.

Animals↗
PubMed1999

[Humoral and cell mediated immunity induced by HBV-S gene recombinant retroviral vector].

OBJECTIVE: To investigate the effectiveness of recombined retrovirus vector in gene therapy. METHODS: The retroviral vector PLXSN-S was constructed and transferred into PA317 by means of electroporation, then HepG2, P815, and EL4 cells were infected with the pseudovirus produced from PA317. In the meantime the gene immunization of PLXSN-S was also studied. RESULTS: HBsAg was expressed variously in the eukaryotic cells mentioned above and successfully evoked antibody response and CTL response to HBsAg after gene immunization. CONCLUSION: Intramuscular DNA immunization represents an efficient technique for priming CTL and antibody response to HBsAg. PLXSN may be used as an effective vector to carry genes of interest to target cells and immunization with it's DNA vaccine might be clinically useful for gene therapy.

Genetic Therapy↗
PubMed1999

[Expression of HBsAg by using various eukaryotic expression vectors].

OBJECTIVE: To establish efficient eukaryotic expression system of HBsAg and its variants. METHODS: A series of expression vectors were constructed by cloning HBV S gene and its mutant genes from recombinant vector pBluescript pBKS(+)-HBs containing S gene and its mutant genes into eukaryotic expression vectors: pMEP4, pCEP4, pLXSN, PXT1, pcDNA3. These recombinant eukaryotic expression vectors were transfected into human hepatocellular carcinoma cells (HepG2). RESULTS: The cell lines expressing recombinant proteins were stably established. CONCLUSION: All expression vectors could express HBsAg and its variants, but their transfecting efficiency, expressing efficiency and stability of expression were different. The establishment of highly efficient expression system in this study paves the way for further study on biologic characters of HBsAg variants, genetic immunization and genetic therapy.

Eukaryotic Cells↗
PubMed1999

Enzyme-linked immunoelectrotransfer blotting analysis of human serologic responses to infective hookworm larval antigen.

OBJECTIVE: To explore the possibility of using specific antigens for immunodiagnosis of hookworm disease in endemic area. METHOD: Infective third-stage larvae of the canine hookworm, Ancylostoma caninum (A. caninum), were prepared as the source of antigen. Enzyme-linked immunoelectrotransfer blotting (EITB) was employed as an immunodiagnostic method. RESULTS: Two immunodominant bands of hookworm antigens (42 kDa and 55 kDa) were recognized by the sera of hookworm-infected patients (serum dilution 1:200; antigen centrifuged at 36,000 r/m for 20 minutes, but not by sera from negative controls. CONCLUSION: The 42 kDa and 55 kDa A. caninum antigens might be the specific antigens that could be used for immunodiagnosis of hookworm disease in endemic area.

Ancylostoma↗
PubMed1999

[Expression of recombinant inserting mutants of HBsAg in vitro and its antigenic analysis].

OBJECTIVE: To study the immunological characteristics of two inserting variants of HBsAg as further to elucidate the role of inserting mutants in the development of HBsAg-negative chronic hepatitis B. METHODS: The inserting mutants of HBsAg were constructed by PCR-mediated mutagenesis in vitro. Epstein-Barr virus vector pCEP4 and retrovirus vector PXT1 carrying the mutant genes of HBsAg were transfected into mammalian cells. The affinity of polyclonal and monoclonal antibodies against HBsAg for mutant antigens were studied by ELISA and western blot. RESULTS: Two insertions were introduced into s gene, and a six nucleotide insertion introduced two aminoacids (Arg and Ala) between codons 122 and 123 of the s polypeptide, whereas a nine nucleotide insertion introduced three aminoacids(Arg, Gly and Ala) between codons 123 and 124. These s genes were subcloned into two eukaryotic expression vectors (pCEP4 and PXT1), and the recombinant eukaryotic expression plasmids had been constructed, which could express s polypeptide in mammalian cells. Cell lines expressing wild-type or mutant-type HBsAg stably were obtained after transfection of these vectors into mammalian cells. Two two inserting variants failed to react with polyclonal and monoclonal antibodies against HBsAg by ELISA and Western blot. CONCLUSION: The insertions may result in a conformational change of the s protein, and affect its antigenicities, suggesting that the inserting mutations may be critical for immunoescape of HBV and in part responsible for chronicity of HBsAg-negative patients.

Epitopes↗
PubMed1999

[The effect of hepatitis B virus x protein on cell cycling].

OBJECTIVE: To study the effect of HBx protein on cell cycle progression and its molecular mechanism. METHODS: The eucaryotic expression vector pCEP4 of HBx gene was constructed and introduced into HepG2 cells. The HepG2 cells transfected with X gene (X cell) were synchronized in a quiescent state by culture of serum deprivation. Flow cytometry, immunohistochemical and Western Blot analysis were performed. RESULTS: 70% HepG2 cells transfected with pCEP4 (X0 cells) was induced in G0-G1 phase, only 56% X cells in G0-G1 phase, almost identical to its parental HepG2 cells cultured in serum medium. To further understand the molecular mechanism of cell cycle progression, the p21CIP1/WAF1 and PCNA were examined. HBx was found to strongly increase the level of PCNA in X cells (86 +/- 3)% compared with X0 cells (9 +/- 5)%, and greatly decrease the level of p21CIP1/WAF1 protein in X cells (16 +/- 6)% compared with X0 cells (86 +/- 8)% (P < 0.001). CONCLUSIONS: These data suggest a molecular mechanism by which HBx likely contributes to viral carcinogenesis. By deregulating cell cycle checkpoint control, HBx could participate in the selection of cells that are genetically unstable, some of which would accumulate unrepaired transforming mutations.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Length of protection by murine vaccination with living infective third-stage hookworm larvae.

OBJECTIVE: To determine the length of protection by murine immunization with living third-stage hookworm larvae (L3) as measured by reduction in worm burden and host serologic antibody responses. METHODS: Outbred male (Kunming strain) mice were immunized subcutaneously with 500 L3 once every 2 weeks for a total of immunization for 3 times, and then challenged orally with 1000 L3 for 1 to 8 weeks after the final immunization. Host protective immunity was determined both by the reduction in worm burden as measured by the number of L3 recovered from murine lungs 48-hour post-challenge, as well as by measurement of circulating antibodies. Histopathological responses were also examined. Non-immunized mice served as negative controls. RESULTS: The protection by L3 immunization declined over time. One or 2 weeks after the final immunization, worm burdens were reduced 72% and 77.5% after challenge respectively. In contrast, only 37% reduction in worm burden was observed when the L3 challenge was delayed by 4 weeks and protection was almost entirely lost when there was an 8 week delay between the time of final immunization and challenge. The reduced level of protection over time partially correlated with diminishing L3-specific antibody responses. Host inflammation in the lungs of immunized mice also diminished. CONCLUSION: The protection afforded by living L3 immunization is maximal for the first two weeks after immunization, but then declines significantly over the ensuing weeks.

Ancylostoma↗