Establishment and characterization of a rat pepsin-producing gastric cell line (OUMS-37)
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Animals↗
Biomedical subjects
C Gao
Publications and source records attributed to C Gao.
Carotenoid glycoside esters from the thermophilic bacterium meiothermusruber
The thermophilic bacterium Meiothermus ruber produces a series of carotenoid glycoside esters. The major carotenoid has been identified as 1'-beta-glucopyranosyl-3,4,3',4'-tetradehydro-1', 2'-dihydro-beta,psi-caroten-2-one (1). It is acylated at the 6' '-position of the glucose unit by a series of C10-C17 fatty acids. The structure of 1 was established by spectral means, including complete assignment of the 1H and 13C NMR resonances by inverse 2D NMR spectroscopy. These carotenoids are thought to play roles in stabilizing membranes of this thermophilic organism.
Journal Article↗
Functional group I metabotropic glutamate receptors in submucous plexus of guinea-pig ileum.
Intracellular recording methods and immunostaining revealed the existence of functional group I metabotropic glutamate receptors (mGluRs) in submucous plexus neurons of guinea-pig ileum. Selective group I, but not groups II or III metabotropic glutamate receptor agonists induced concentration-dependent, slowly-activating depolarizing responses. Group I metabotropic glutamate receptor antagonism observed with (S)-4-carboxyphenylglycine (S-4-CPG) (100 - 600 microM) was competitive as determined by Schild analysis (pA(2)=3.81+/-0.02). Neither the group II and III metabotropic nor ionotropic glutamate receptor antagonists altered responses evoked by group I receptor agonists. Immunoreactivities for metabotropic glutamate 1alpha and 5 receptors were found to locate exclusively in neurons in the submucous plexus of guinea-pig ileum with the highest density around the cell bodies. The results suggest that group I metabotropic glutamate receptors are functionally expressed in the submucous plexus of guinea-pig small intestine.
Animals↗
Development and characterization of an SV40 immortalized porcine ameloblast-like cell line.
Enamel is secreted as a protein matrix by the ameloblasts. These same cells then control the maturation of the enamel matrix, secreting proteinases that hydrolyze proteins as mineralization progresses, until mature enamel containing less than 1% protein by weight remains. Further understanding of the factors that control ameloblast function and differentiation requires an in vitro cell culture system. In this study, we report immortalization of enamel organ epithelial cells and the selection of a cell line with characteristics of ameloblasts. Porcine enamel organ cells were dissected from unerupted porcine molars, cultured in serum-free medium, and passaged twice. These cells were transfected with an origin-of-replication defective SV40 plasmid by calcium phosphate precipitation, and a cell line with mRNA expression characteristic of ameloblasts was cloned. This cell line (PABSo-E) expressed mRNA for amelogenin, matrix metalloproteinase-20 (enamelysin), and enamel matrix serine proteinase 1 (EMSP1), but not ameloblastin. PABSo-E cells have been passaged more than 55 times, while continuing to maintain characteristics of ameloblasts. These cells will be useful for future studies of ameloblast function.
Ameloblasts↗
Activation of recombinant bovine matrix metalloproteinase-20 and its hydrolysis of two amelogenin oligopeptides.
Enamelysin is a matrix metalloproteinase (MMP-20) secreted by ameloblasts, previously shown to hydrolyze recombinant amelogenin. The purpose of this study was to use recombinant MMP-20 to further investigate the specific hydrolysis of peptide fragments containing cleavage sites for tyrosine-rich amelogenin peptide (TRAP) and leucine-rich amelogenin peptide (LRAP). MMP-20 cDNA was isolated from a subtracted bovine cDNA library, reconstructed into pRSET A vector, and overexpressed in BL21 Escherichia coli. The recombinant MMP-20 was purified using Mono-S ion exchange and nickel affinity chromatography. The proteinase was renatured by dialysis against buffer containing 50 microM zinc and 5 mM calcium and autolysed to form several active fragments. The varying sizes and activities of the activated enzyme fragments appeared to be due to sequential autolysis at different location of the carboxyl terminus of the intact enzyme. Two synthetic peptides corresponding to amelogenin amino acid sequences 36-49 and 181-188 were hydrolyzed by the activated rMMP-20. Mass spectrometry and amino acid composition analysis showed that the cleavage sites were between the tryptophan and leucine (45 and 46) for TRAP and between proline and alanine (186-187) for LRAP. These results indicate that MMP-20 can be autoactivated, and activated MMP-20 has a functional role in the initial cleavage of amelogenin.
Alanine↗
Activation of caspases in p53-induced transactivation-independent apoptosis.
Though p53-induced apoptosis plays an important role in tumor suppression, the mechanism(s) by which p53 induces apoptosis is still unclear. To elucidate the p53-induced apoptotic pathway, we examined the role of p53 transactivation activity and caspase in J138V5C cells carrying a human temperature-sensitive (ts) p53 mutant (138Ala-->Val). The results showed that p53-induced apoptosis was not blocked by cycloheximide, which effectively prevented the expression of p53 target genes, indicating that transactivation was not essential for p53-induced apoptosis in this system. Western blot analysis showed that PARP, CPP32 and ICH-1 precursors were cleaved during apoptosis. The CPP32-preferential tetrapeptide inhibitor Ac-DEVD-CHO blocked the cleavage of ICH-1 and PARP precursors, suggesting that CPP32 or some other DEVD-sensitive caspase(s) is the upstream activator of ICH-1. We also examined the role of the Fas pathway by using Fas and Fas ligand-neutralizing antibodies. Both antibodies failed to block p53-induced apoptosis, suggesting that the Fas pathway was not essential for p53-induced apoptosis in this system. Taken together, our results indicate that p53-induced, transactivation-independent apoptosis in Jurkat cells involves sequential activation of CPP32 or some other DEVD-sensitive caspase(s) and ICH-1, via a Fas-independent pathway.
Apoptosis↗
Maintenance of near-diploid karyotype of PA-1 human ovarian teratocarcinoma cells due to death of polyploid cells by chromosome fragmentation/pulverization.
Chromosome instability (polyploidy or aneuploidy) is one of the characteristics of malignant tumors. Human teratocarcinoma cell line PA-1, which was established more than 10 years ago, consists of a majority of near-diploid cells and a minority of polyploid cells, indicating that it is karyologically very stable. In the present study we investigated this genomic stability from the view point of cytogenetics. Cleavages and breaks in the chromosome were found in the metaphase of PA-1 polyploid cells, accompanied by the formation of polynucleosomal DNA fragments. These findings were absent in the near-diploid cells. In addition, polyploid cells did not show colony-formation ability by in situ analysis of cytogenetics in each colony. Thus, the maintenance of the near-diploid karyotype in PA-1 cells may be due to a blockage in the M-phase of the polyploid cells by functional mitotic checkpoints, if any, leading to cell death due to inability to enter the next cell cycle.
Chromosome Banding↗
Cytogenetic characteristics and p53 gene status of human teratocarcinoma PA-1 cells in 407-445 passages.
To study why the human teratocarcinoma cell line PA-1 maintains a stable near-diploid karyotype even after it has been cultured for more than twenty years, p53 gene status of the cell line in 407-445 passages were investigated in detail by DNA sequence analysis and a yeast function status assay. Direct sequence analysis of RT-PCR products showed both wild and mutated bands (p53 codon 239 mutation). Consistent with the above results, the functional assay showed that one allele of the p53 gene was active (wild), while the other was inactive (mutant). In addition, the PA-1 cells expressed the p21 protein to a lesser extent than normal human fibroblasts. Though many lines of evidence have shown that mutant p53 works dominant-negatively, our results suggest that mutation in a p53 allele alone can not induce cytogenetic instability.
Aneuploidy↗
Mitral valve replacement with complete mitral leaflet retention: operative techniques.
BACKGROUND AND AIMS OF THE STUDY: This report describes surgical indication and operative technique of complete preservation of the mitral valvular and subvalvular apparatus during mitral valve replacement. METHODS: Twenty patients, 12 with rheumatic lesions and eight with congenital lesions, were operated between 1991 and 1996. The left atrium was opened using a trans-septal approach through the right atrium in 17 patients, and at the intra-atrial groove in three. The valve was sized without excising any mitral valvular or subvalvular tissue. Teflon pledget-reinforced horizontal mattress valve sutures were passed from the left atrium, through the mitral annulus, around the free edge of mitral leaflet, and up through the prosthetic sewing ring. The prosthetic valve was seated and the sutures tied, reefing the native leaflets and compressing them between the sewing ring and native annulus. Thus, chordal tension on the ventricle was evenly maintained. RESULTS: There was no operative or late death. Postoperative results were excellent. Echocardiography showed that none of the patients had any observable anterior leaflet and redundant subvalvular tissue in the left ventricular outflow tract (LVOT); thus, neither LVOT obstruction nor interference with prosthetic valve function occurred. CONCLUSIONS: Based on these findings, it is suggested that when mitral valve replacement is required in patients with mitral insufficiency (MI) or MI with mild stenosis, the mitral valvular and subvalvular tissue should be completely preserved.
Adult↗
[Study on seroprevalence of Helicobacter pylori infection among upper digestive tract cancer patients and their kindreds].
OBJECTIVE: In order to analyse the association between Hp infection and the risk of upper-digestive tract cancer. METHODS: In Huaian and Pizhou cities, Jiangsu province, Hp IgG quantitative-enzyme-immunoassay methods was used to identify IgG to H.pylori in the serum of 312 cases of upper-digestive tract cancer patients and their kindreds. RESULTS: (1) The level of IgG to H. pylori and the IgG positive rate (50.0%) in gastric cancer patients were both higher than that of cardia and esophageal cancer patients (P > 0.05, chi 2 test) but no significant differences were observed between cardia and esophageal cancer patients, 3 types of cancer patients and their kindreds; (2) the overall positive rates of both patients and kindreds in gastric cancer families (27.1%) were significantly higher than that of cardia or esophageal cancer families (P < 0.05) but no significant differences were observed between cardia and esophageal groups. CONCLUSION: H.pylori infection was not thought to be correlated with the development of gastric cancer, although higher clustering of Hp infection in families afflicted with gastric cancer was noticed.
Adult↗
hOGG1 Ser326Cys polymorphism and lung cancer susceptibility.
The human homologue of the yeast OGG1 gene, hOGG1, has been cloned, and its genetic structure has been determined. Several polymorphisms in the hOGG1 gene were detected in the Japanese populations, and among them, the Ser-Cys polymorphism at codon 326 has been shown to have a functional difference in complementation of mutant Escherichia coli that is defective in the repair of 8-hydroxyguanine. Activity in the repair of 8-hydroxyguanine is greater in hOGG1-Ser326 protein than in hOGG1(326) protein. Because many environmental carcinogens produce 8-hydroxyguanine residue and mismatching to this modified base potentially causes oncogenic mutations, the capacity to repair these lesions can be involved in cancer susceptibility in human beings. We, therefore, examined allele distributions of the Ser326Cys polymorphism in a case-control study of male lung cancer in Okinawa. The analyses based on 241 cases and 197 hospital controls disclosed the following findings. (a) Those with the Cys/Cys genotype were at an increased risk of squamous cell carcinoma and nonadenocarcinoma compared to those with the Ser/Cys and those with the Ser/Ser genotypes combined. The odds ratios adjusted for age and smoking history were 3.01 (95% confidence interval, 1.33-6.83) and 2.18 (95% confidence interval, 1.05-4.54), respectively. (b) The odds ratios for other histological subtypes of lung cancer or those in total were not significant. Those for Cys/Cys or Ser/Cys genotype against Ser/Ser did not reach statistical significance in any cell type. (c) The distributions of this polymorphism varied for different populations (Chinese, Japanese, Micronesians, Melanesians, Hungarians, and Australian Caucasians), with much less prevalence of Cys allele in the latter three populations. Although our sample size was limited, these results indicate that the Ser326Cys variant may be related to squamous cell lung cancer susceptibility. The Cys/Cys genotype appears to be more susceptible to squamous cell carcinoma, although the risk is less than that previously reported to be associated with the CYP1A1 gene. Further studies are needed to assess the importance of the interpopulation variation to cancer susceptibility.
Adult↗
KN-62 provides neuroprotection against glutamate-induced excitotoxicity in neurons.
AIM: To study the effects of KN-62, an inhibitor of Ca(2+)-calmodulin dependent protein kinase II (CCDPK II), on the damage of cortical neurons and mechanisms of the loss of CCDPK II activity induced by sodium glutamate (Glu). METHODS: CCDPK II activity was measured by 32P incorporation and backphosphorylations of endogenous proteins were studied by autoradiography. RESULTS: 1) KN-62 provided partial protection against excitotoxical damage only before Glu (100 mumol.L-1, 10 min) treatment. 2) KN-62 markedly suppressed the loss of CCDPK II activity induced by Glu from 48.0% to 90.6%. 3) Backphosphorylation of endogenous proteins (especially the 50 kDa protein) reduced to 78.2% of control after treatment with Glu, and the reduction was protected with KN-62 added before Glu. CONCLUSION: KN-62 provided the protection against excitotoxicity and the loss of CCDPK II activity as well as backphosphorylation of endogenous proteins induced by Glu. The neuroprotection provided by KN-62 was due to the inhibition of autophosphorylation of CCDPK II.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
Study of activity of promoter from mouse alpha 2(I) procollagen gene.
OBJECTIVE: To clarify the segment and sequence in mouse alpha 2(I) procollagen gene which are responsible for high transcriptional activity during fibrogenesis. METHODS: This study was focused on further fractional analysis of 2 kb-length mouse alpha 2(I) procollagen gene promoter activity. Six chimeric genes were constructed in which various lengths of sequences between 2000 bp upstream of the start of transcription of the mouse alpha 2 (I) procollagen gene and 54 bp downstream of this site were fused to chloramphenicol acetyltransferase (CAT) reporter gene. These recombinant plasmids were transfected transiently to collagen-producing cells (NIH/3T3) and non-collagen-producing cells (COS7) with liposomal transfection method. The activities of putative promoters were observed and compared by means of CAT measurement in the transfected cells. RESULTS: The highest and partial cell specific CAT expression was observed in construction driven by -780 to bp fragment. The construction containing sequence deleted the proximal 500 bp from the transcription start site and part of exon I, and resulted in the lowest CAT expression. CONCLUSIONS: Some essential elements might exist in the 500 bp fraction proximal to transcription start site and part of exon I in mouse alpha 2(I) procollagen gene. The high potential promoter sequence between -780 bp from the start of transcription site and bp from this site is of great significance in our following study of searching for specific DNA-binding proteins in activated collagen-producing cells.
3T3 Cells↗
[Changes of surface roughness and glossiness of the composite resins during polishing].
OBJECTIVE: To investigate the changes of surface roughness and glossiness of the composite resins during polishing. METHODS: Nine conventional composite resins were evaluated. Composite specimens were polymerized on celluloid strip, so, smooth surfaces were obtained for each specimen, then the smooth surface of the specimens were sequentially polished with diamond polishing papers grits #240, #320, #400, #600, #800 and #1200. The roughness and glossiness of the central surface at 60 degrees reflex angle were measured. RESULTS: The results showed that the values of roughness decreased steadily when specimens were polished with sequential polishing paper from coarse to fine one. A further polishing with grit #800, the values of roughness resumed to the pre-polishing values in all the composite specimen. The change of values of glossiness is very small within polishing with #240-#600. A further polishing with grit #800 and #1200, the values of glossiness increased jumpily. The values of glossiness of five composite resins reached or surpassed the level of pre-polishing. CONCLUSION: This study indicates that fine surface would not be gained until the composite resins were polished with grit #800 and #1200 polishing paper.
Composite Resins↗
[Applications of porous polymeric materials and its biocompatibility].
With the barrier materials, guided tissue regeneration materials and hybrid artificial organs as the representafive materials, the applications of polymer skeletal materials in biomedical fields are introduced in this paper. Based on the results of the induced carcinoma, collagenous encapsulation and chronic inflammation around implanted polymers, the effects of polymers topography on biocompatibility are discussed, and the importance of topographical compatibility of materials is emphasized.
Biocompatible Materials↗
[Aspirin inhibited the adhesion of platelets to neutrophil in patients with acute myocardiac infarction].
OBJECTIVE: To investigate the effect and mechanism of aspirin(ASA) on platelet-neutrophil adhesion. METHODS: Using rosette forming assay to observe the effect of ASA on the binding of platelets to neutrophil and radioimmunoassay to observe the effect of ASA on the thrombin-induced expression of GMP-140 on the surface of human platelets. RESULTS: Patients with acute myocardial infarction showed a significant increase in neutrophil-platelet adhesion (63.3 +/- 7.8)%, (n = 20, P < 0.001) as compared with normal subjects(16.5 +/- 2.6)% (n = 20). Thrombin promoted adhesion by increasing the expression of GMP-140 on the surface of human platelets. When the concentration of thrombin was 0.5 U/ml, the rate of neutrophil-platelet adhesion and the number of molecular of GMP-140 on the surface of platelet was (64.2 +/- 4.2)%, and (1.80 +/- 0.20) x 10(3) per platelet respectively. At high concentration, ASA significantly inhibited thrombin (0.5 U/ml) stimulated platelets binding to neutrophils and expressing GMP-140 on their surface. When the final concentration of ASA was 500,5000 micrograms/ml, the ratio of thrombin-stimulated platelets binding neutrophils was (34.7 +/- 3.8)%, (21.2 +/- 3.6)% respectively (n = 20, P < 0.01); the number of molecular of GMP-140 expressing on the surface of platelet was (1.02 +/- 0.24) x 10(3), (0.68 +/- 0.18) x 10(3) per platelet respectively (n = 9, P < 0.001). CONCLUSIONS: It contributes to the antithrombosis of ASA that inhibiting platelet-neutrophil adhesion by down expression of GMP-140 on the surface of human platelets.
Aspirin↗
[Advances in audiology in China].
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Audiology↗
Regioselective synthesis of ethoxylated glycoside esters using beta-glucosidase in supersaturated solutions and lipases in organic solvents
Three ethoxylated glycosides, tetraethylene glycol beta-D-glucoside, tetraethylene glycol beta-D-xyloside, and methoxy triethyleneglycol beta-D-glucoside, were prepared via almond beta-glucoside-catalyzed (trans)glycosylation carried out in supersaturated solutions of glucose or p-nitrophenyl beta-D-xyloside and the respective polyethylene glycols. The products were isolated and further modified by enzymatic esterification with Candida antarctica and Mucor miehei lipases. The latter enzyme showed a much greater selectivity for the primary hydroxyl group on the polyethylene glycol chain of the glucoside substrate, thus enabling us to obtain exclusively the corresponding monoester, omega-O-oleoyl tetraethylene glycol beta-D-glucoside. Novozyme was used for the preparative synthesis of two other monoesters, 6-O-oleoyl (methoxy triethyleneglycol) beta-D-glucoside and omega-O-oleoyl tetraethylene glycol beta-D-xyloside. Two diesters, di-oleoyl tetraethylene glycol beta-D-glucoside and tetraethylene-bis(6-0-oleoyl glucoside) were also synthesized in good yields using this lipase. Copyright 1998 John Wiley & Sons, Inc.
Journal Article↗