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Biomedical subjects

J Gao

Publications and source records attributed to J Gao.

At least 235 records · Page 13Linked to original sources
PubMed1999

[The mediation effects of endothelin-1 on human mesangial cell proliferation stimulated by thrombin].

OBJECTIVE: To investigate the effects of endothelin-1 (ET-1) on mesangial cell proliferation stimulated by thrombin. METHODS: With cultured human mesangial cells (HMC), the following tests were performed. (1) Stimulative tests: After thrombin stimulation, HMC proliferation was determined by MTT method, concentration of ET-1 in supernatant was measured with radioimmunoassay (RIA) and preproendothelin-1 (ppET-1) mRNA expression of HMC was analysed by Northern blot hybridization. (2) Inhibitory test: The influence of ET-1 inhibitors on the HMC proliferation following thrombin stimulation at three different levels, i.e. ET-1 antiserum, selective ET receptor-type A (ET(A)) antagonist and antisense oligodeoxynucleotide for ppET-1, was measured by MTT test respectively. RESULTS: (1) HMC proliferation was stimulated by thrombin in dose dependent manner and in relation to the time of stimulation. The peak growth level was attained in thrombin concentration of 16 U/ml and incubation time of 16 hours. ET-1 secretion by HMC was increased in parallel with the dose curve and time curve of HMC proliferation; HMC ppET-1 mRNA expression was up-regulated by thrombin 16 U/ml with incubation time of 8 hours and 16 hours respectively (7.9 fold, 3.4 fold versus control group). (2) ET-1 inhibitors, ET-1 antiserum, selective ET(A) receptor antagonist and antisense oligodeoxynucleotide for ppET-1 all significantly inhibit HMC proliferation stimulated by thrombin. CONCLUSION: Thrombin stimulates HMC to produce ET-1 and ET-1 mediates the HMC proliferation.

Cell Proliferation↗
PubMed1999

[The establishment of a human pancreatic mixed ductal-endocrine carcinoma cell line].

OBJECTIVE: Establishment of a human pancreatic mixed ductal-endocrine carcinoma cell line. METHODS: A specimen of this type of cancer was obtained from a male patient at the head of pancreas. The tumor tissue was minced into pieces and inoculated subcutaneously in nude mice. With two successive subcutaneous implants, a piece of tumor tissue taken from the 2(nd) implanted neoplasm of a nude mouse was minced into minute tissue masses and inoculated in a media containing 10% fetal bovine serum. RESULTS: Currently, it has been passed to the 55(th) passage. Cells of this cell line (PC-EN) kept simultaneously the morphologic patterns of a pancreatic ductal and endocrine tumor which were verified by histochemistry and immunohistochemistry assays. Some of the PC-EN cells showed presence of neuroendocrine granules by electron microscopy. The growth rate of this cell line was relatively low. Kakryotype analysis showed two cell populations with its major mode of chromosomes numbers as 48 in one, and 56 in the other. Study on K-ras gene demonstrated that PC-EN harbored a mutated codon 12. Several gastrointestinal hormones and CEA were detected in PC-EN cells and in the supra-cultured medium using radioimmunoassay. CONCLUSIONS: The cellular and molecular biologic characteristics of PC-EN cells illustrated that this cell line preserved the morphology of a pancreatic ductal and endocrine tumor and possessed a special growth property, chromosome karyotype, and mutation of Ki-ras gene, but also showed a biologic exocrine and endocrine functions of the pancreas. The establishment of PC-EN cell line will provide a useful model in vitro for further investigating the cellular and molecular biology of exocrine and endocrine tumors of the pancreas.

Aneuploidy↗
PubMed1999

[The mechanism of bystander effect in herpes simplex virus thymidine kinase/ganciclovir-mediated gene therapy].

OBJECTIVE: To study the mechanism of bystander effect in herpes simplex virus thymidine kinase (HSV-TK)/Ganciclovir (GCV)-mediated gene therapy. METHODS: Recombinant retroviral vectors expressing HSV-TK and beta-Galactosidase (Lac Z) genes were constructed and transferred into pancreatic carcinoma cell line respectively. Cell counting was used to detect the growth inhibition rate of HSV-TK-transduced cells in presence of GCV. Taking Lac Z-transduced cells as bystander cells, the bystander effect was detected by MTT method, and its mechanism was studied by the experiments of supernatant shifting, Verapamil inhibition and ultrastructural observation. RESULTS: The growth inhibition rate of the HSV-TK-transduced cells in the presence of GCV was 92.1%, which was obviously 4.9% and 3.2% higher than of the non-and control vector-transduced cells. Mixed cells containing only 10% of HSV-TK-transduced cells showed 39.0% reduction of the proliferation, which meant there was an obvious bystander effect in the system. However this effect disappeared when transferring GCV-containing supernatant of HSV-TK-transduced cells to the parent cells and could be reduced significantly when verapamil was added in the medium, indicating that this bystander effect requires cell-cell contact. Gap junctions were observed existing between PC-2 cells by electron microscopy. CONCLUSION: The bystander effect in HSV-TK/GCV-mediated gene therapy occurs by transfer of GCV metabolite from cell to cell through gap junction.

Antiviral Agents↗
PubMed1999

[Analysis on the dietary lipid pattern in different areas of China].

Based on the "Total Diet Study" conducted in 1990, food samples from urban and rural inhabitants in the four regions of China(North I, North II, South I and South II) were analyzed separately. The results showed that, except the status in South II, the amount of fat and cholesterol intake existed obvious differences between urban and rural inhabitants in the same region. The dietary fat and cholesterol intake of rural inhabitants in North II region was obvious inadequate. Dietary fat intake of urban inhabitants was high and the cholesterol intake was higher than the level of 300 mg per capita. The results showed that the ratio of polyunsaturated fatty acids was relatively low but the ratio of monounsaturated fatty acids was relatively high for dietary fat in two southern regions. It might be beneficial to increase plant oil which contains high amount of polyunsaturated fatty acids for the inhabitants in southern regions. From these results, we concluded that the dietary lipids intake of Chinese inhabitants was generally appropriate. Considering the great difference in economic development and dietetic culture, the dietary suggestions should be different regions to regions.

Cholesterol↗
PubMed1999

[Evaluation of methods of drug release rate in root canal disinfection controlled-release delivery system containing metronidazole].

OBJECTIVE: To measure the release rate of drug in controlled-release delivery system containing metronidazole. METHODS: Drug release tests in vitro, in vivo and through the roots of extracted teeth were performed. The release rate of metronidazole was calculated after 1 day, 3 days, 7 days and 10 days, and the results were statistically analyzed. RESULTS: Significant difference was observed among the total drug release rate in vitro, in vivo and through the roots of extracted teeth (P < 0.01). There was no statistically significant difference between the release test in vivo and through the roots of extracted teeth in vitro (P > 0.05). CONCLUSION: The method of using extracted teeth and the controlled release medium at 37 degrees C, pH7.4 was close to the situation in vivo, and it was an effective method to measure the drug release rate of the root canal disinfection controlled-release delivery system.

Anti-Infective Agents, Local↗
PubMed1999

[Preparation, purification and identification of sialic acid from Escherichia coli C-8].

Colominic acid produced from Escherichia coli C-8 was purified by ammonia sulfate precipitation, dialysis and concentration. After hydrolysis of colominic acid at a pH of 2.5, at 70 degrees C for 4 h, sialic acid was obtained, then purified by chromatography on Dowex1-x8. Analysis of thin-layer chromatography and absorption spectrum of sialic acid in the orcinol/Fe3+/HCl and the periodic acid/thiobarbituric acid confirmed that its purity was identical with that of standard sample.

Chromatography, Thin Layer↗
PubMed1999

[Experimental therapy of Pagumogonimus skrjabini infection in rats with triclabendazole].

AIM: To observe the therapeutic effect of triclabendazole in rats infected with Pagumogonimus skrjabini. METHODS: Metacercariae of P. skrjabini were isolated from crabs (Sinopotamon) collected from two endemic areas (Weiyuan County of Sichuan Province and Wansheng District of Chongqing Municipality). Wistar rats were each infected intraperitoneally with metacercariae. One month and two months after infection, the infected rats were treated with triclabendazole at the total dosage of 300 mg/kg over 2 days, 450 mg/kg over 3 days and 600 mg/kg over 3 days, respectively. RESULTS: The worm reduction rates were 50%, 80% and 87% respectively one month after completion of tretment. Dead worms (about 1 mm size) recovered from the muscles, liver, abdominal cavity, chest cavity and lungs were signicantly diminished in size and weight in comparison with those of the control group. Many large (about 1 cm) black-colored distended worm cysts usually with two adult worms and many eggs were found in the lungs of the control rats. Most worm cysts in the treated groups of rats were found to be atrophied, changing into hemorrhagic-necrotic patches. CONCLUSION: Triclabendazole is highly active against P. skrjabini in rats.

Animals↗
PubMed1999

[Effects of blocking the TGF alpha-EGFR autocrine loop on the growth of human pancreatic carcinoma cells in vitro].

OBJECTIVE: Investigate the effects of blocking the TGF alpha-EGFR autocrine loop on the growth of human pancreatic carcinoma. METHODS: The pCMV-AS-EGFR, a recombinant vector expressing antisense EGFR under the control of human CMV promotor was constructed and transfected the transformant PC-7/AS-TGF alpha cell line cells, which had been transfected by a recombinant retroviral vector expressing antisense TGF alpha. G418 resistant colonies were isolated and identified as PC-7/AS-TGF alpha/AS-EGFR. The integration and expression of exogenous and endogenous genes were detected by Southern blot and Northern blot analysis. Apoptosis was detected by DNA fragmentation, flow cytometry and in situ cell death detection. RESULTS: The cells which were double-transfected by the recombinant vectors showed the integration and expression of exogenous genes, and the downregulation of endogenous EGFR and cyclin D1 mRNA. 125I-EGF ligand binding test showed the binding affinity of the EGFR on the cell surface also reduced. The inhibition effect of cotransfecting of antisense TGF alpha and antisense EGFR was remarkable as compared with that of antisense TGF alpha alone. The incorporation rate of 3H-TdR reduced from 25% to 14.5%, and the growth inhibition rate increased from 78.6% to 86.0%. The ability of soft agar colony-formation was completely suppressed. CONCLUSIONS: These observations strongly support that the blockage of the expression of autocrine growth factor TGF alpha and its receptor EGFR was a potent way in circumventing the malignant properties of the pancreatic carcinoma cells.

Cell Division↗
PubMed1999

[Fluorescence spectra of lanthanide coordination compounds].

In this paper, the recent progress in fluorescence spectra of lanthanide coordination compounds including photophysics and photochemistry is briefly reviewed and the application of lanthanide complexes as fluorescent probes to structural analysis of coordination compounds and biomolecular systems is summed up.

English Abstract↗
PubMed1999

[Bonding behavior of 4f orbital].

In this paper, the bonding behavior of 4f orbital in lanthanide coordination compounds was discussed and corresponding theory and research methods were summed up with 36 references.

English Abstract↗
PubMed1999

[Transmission grating spectrograph for soft X-ray spectrum measurements with a pre-optics].

A novel diffraction spectroscopic instrument consisting of a large area transmission grating and a grazing-incidence pre-optics comprising of a toroidal mirror, a slit and a cylindrical mirror has been implemented. A nearly perfect stigmatism and a medium spectral resolution are due to the separation of the focusing and dispersing function. The experimental results show that it is possible to construct large area transmission grating spectrograph with high collecting efficiency and good spatial resolution.

English Abstract↗
PubMed1999

Cloning and mutational analysis of human malonyl-coenzyme A decarboxylase.

Malonyl coenzyme A (CoA) decarboxylase (E.C.4. 1.1.9) catalyzes the conversion of malonyl CoA to acetyl CoA. The metabolic role of malonyl CoA decarboxylase has not been fully defined, but deficiency of the enzyme has been associated with mild mental retardation, seizures, hypotonia, cardiomyopathy, vomiting, hypoglycemia, metabolic acidosis, and malonic aciduria. Here we report the isolation and sequencing of the human gene encoding malonyl CoA decarboxylase, and the identification of a mutation causing malonyl CoA decarboxylase deficiency. Human malonyl CoA decarboxylase cDNA sequences were identified by homology to the goose gene, and the intron/exon boundaries were determined by direct sequencing of a PAC clone containing the entire human gene. The 1479 basepair human cDNA is 70 percent identical to the goose sequence, and the intron/exon boundaries are completely conserved between the two species. The genetic mutation underlying malonyl CoA decarboxylase deficiency was determined in a patient with clinical features of this defect, malonic aciduria, and markedly reduced malonyl CoA decarboxylase activity.

Amino Acid Sequence↗
PubMed1998

Gene cloning, RNA distribution, and functional expression of mCX3CR1, a mouse chemotactic receptor for the CX3C chemokine fractalkine.

Human fractalkine and its apparent murine counterpart neurotactin are the only members identified so far of the CX3C subfamily of chemokines. Recently, a human fractalkine receptor was identified and named CX3CR1. Here we have identified a mouse counterpart of this receptor. The receptor was identified by analysis of a mouse genomic clone named PC2 isolated by homology hybridization using CX3CR1 as probe. Clone PC2 has a 354-codon open reading frame that has 83% amino acid identity to CX3CR1. PC2 RNA was abundant in brain and lung and comparatively less abundant in lung, liver, kidney, testis, and peripheral blood leukocytes, a pattern similar to that found for CX3CR1. The recombinant fractalkine, but no other chemokines tested, induced chemotaxis and transient increases in [Ca2+]i in HEK 293 cells transfected with PC2, whereas untransfected cells did not respond. Furthermore, fractalkine bound specifically to the transfected cells (Kd=4 nM). Thus, fractalkine is a functional ligand for this receptor and we propose to name it mCX3CR1 for murine CX3C chemokine receptor 1.

Amino Acid Sequence↗
PubMed1998

Interleukin-10 suppresses IP-10 gene transcription by inhibiting the production of class I interferon.

Interleukin-10 (IL-10) selectively inhibited lipopolysaccharide (LPS)-induced chemoattractant cytokine gene expression: levels of IP-10 mRNA were markedly suppressed in IL-10-treated mouse peritoneal macrophages, whereas the expression of the RANTES mRNA was only modestly reduced. IL-10 inhibited IP-10 mRNA accumulation by reducing IP-10 gene transcription as demonstrated by nuclear run-on analysis. Interestingly, the ability of IL-10 to inhibit expression of IP-10 was dependent on the inducing stimulus; IL-10 did not suppress interferon gamma (IFNgamma)- or IFNbeta-stimulated IP-10 transcription or mRNA accumulation. These results suggested that IL-10 might act indirectly to suppress IP-10 expression by inhibiting LPS-induced class I IFN production. This hypothesis was supported by the following observations. First, LPS-induced IP-10 mRNA expression was blocked in cells cotreated with cycloheximide. Second, IL-10 inhibited the production of IFN/beta-mediated antiviral activity. Finally, the IL-10-mediated suppression of LPS-stimulated IP-10 production could be rescued by cotreatment with IFNbeta.

Animals↗