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Biomedical subjects

Y Chen

Publications and source records attributed to Y Chen.

At least 919 records · Page 51Linked to original sources
PubMed2000

Identification of a novel splicing product of the RON receptor tyrosine kinase in human colorectal carcinoma cells.

The RON receptor tyrosine kinase is a 180 kDa heterodimeric protein composed of a 40 kDa alpha chain and a 145 kDa beta chain with intrinsic tyrosine kinase activity. Activation of RON causes cell dissociation, motility and invasion of extracellular matrices, suggesting that RON might be involved in tumor metastasis. We report here the cloning of a novel splice variant of RON in human colorectal carcinoma cell line HT-29. This RON variant is first produced as a single chain precursor with a molecular mass of 160 kDa. Proteolytic cleavage results in a 40 kDa alpha chain and a short form of the beta chain with a molecular mass of 125 kDa. The altered receptor is synthesized from a transcript differing from the full-length RON mRNA by an in-frame deletion of 109 amino acids in the extracellular domain of the RON beta chain. The consequence of the deletion is constitutive activation of the protein with autophosphorylation. Expression of the RON variant in colon epithelial CoTr cells results in increased cell migration and invasion of extracellular matrices. These data suggest that generation of the activated splice variant of RON may contribute to the invasive phenotype of human colorectal carcinomas in vivo.

Alternative Splicing↗
PubMed2000

Effect of polysaccharide krestin on glutathione peroxidase gene expression in mouse peritoneal macrophages.

Polysaccharide krestin (PSK) is a protein-bound polysaccharide extracted from the sporophore Coriolus versicolor. Previously, we found that PSK could reduce the oxidative injury that oxidised low-density lipoprotein (Ox-LDL) produced in monocytes/macrophages, and therefore have some pro-phylactic or therapeutic effect on atherosclerosis. Glutathione peroxidases, including selenium-dependent glutathione peroxidase (SeGPx) and non-selenium-dependent glutathione peroxidase (non-SeGPx, also called glutathione S-transferase [GST]), play an important role in the defence against oxidative injury. In order to find out if the effects of PSK were associated with antioxidant enzymes, we investigated its effect on glutathione peroxidase activity and messenger RNA (mRNA) expression in mouse peritoneal macrophages. Results showed that PSK enhanced SeGPx and non-SeGPx activity, and increased SeGPx and GST-P (pi class GST) mRNA in mouse peritoneal macrophages. In addition, the induction by PSK of the two glutathione peroxidases could be blocked by cycloheximide (30 micrograms/mL), but 5 micrograms/mL actinomycin D and 50 micrograms/mL acetovanilone (a superoxide inhibitor) had no effect. We conclude that PSK improved glutathione peroxidase activity through transcriptional induction of mRNA expression.

Animals↗
PubMed2000

[Effect of domestic glutathione on the alcoholic liver disease].

OBJECTIVE: To evaluate the effect and safety of domestic glutathione (GSH) on serum ALT, AST, SB levels in alcoholic liver disease (ALD) by multicenter, randomized and TAD controlled trial. METHODS: All the 110 patients with ALD enrolled had a history of drinking over 80g-120g daily for 5 years, and were randomized either into GSH (continuous infusion of 600g daily for 30d) or TAD (with the same dosage, course and route as GSH) group. The efficacy and safery were evaluated with clinical and biochemical (ALT, AST and GGT) parameters. RESULTS: After 8 weeks of treatment, the clinical signs were improved at a different degree in both groups. ALT, AST and SB showed no significant difference in the two groups (the efficacy rate of 93% vs 96%, P>0.05). CONCLUSION: The domestic GSH, with a good tolerance and safety, has a sound efficacy in the improvement of clinical signs and hepatic functions.

Adolescent↗
PubMed2000

[Reevaluation of the nomenclature and diagnostic criteria in 477 patients with severe hepatitis].

OBJECTIVE: To explore the possibility of establishing more reasonable nomenclatures and diagnostic criteria for patients with severe hepatitis (SH) through analyzing clinical data of 477 cases of SH. METHODS: The clinical characteristics and outcomes of SH were analyzed according to different criteria. RESULTS: Chronic severe hepatitis (CSH) made up 88.5% of total cases of SH. The survival rate in the patients with hepatic encephalopathy was much lower than that without hepatic encephalopathy. About 1/5 of cases of subacute severe hepatitis (SSH) and CSH had neither ascites nor hepatic encephalopathy. When the period of 2 weeks was used in replace of 10 days for the diagnosis for acute severe hepatitis (ASH), the newly added cases were consistent with the characteristics of ASH. CONCLUSION: We suggest dividing SH into 2 types: encephalopathy and non-encephalopathy by using the nomenclature of fulminant hepatitis and severe type hepatitis, respectively. The late-onset form should be added besides of acute form and subacute form. It seems to use the period of 2 weeks as the new definition of onset time for ASH. The criteria of dividing SH into 3 forms, i.e. ascites, encephalopathy and ascites plus encephalopathy, and the nomenclature recommended by the International Association for the Study of the Liver Subcommittee are not satisfactory when used in clinical cases. The typing of CSH remains to be clarified.

Adolescent↗
PubMed2000

Crystal structure of a Flp recombinase-Holliday junction complex: assembly of an active oligomer by helix swapping.

The crystal structure of a Flp recombinase tetramer bound to a Holliday junction intermediate has been determined at 2.65 A resolution. Only one of Flp's two domains, containing the active site, is structurally related to other lambda integrase family site-specific recombinases, such as Cre. The Flp active site differs, however, in that the helix containing the nucleophilic tyrosine is domain swapped, such that it cuts its DNA target in trans. The Flp tetramer displays pseudo four-fold symmetry matching that of the square planar Holliday junction substrate. This tetramer is stabilized by additional novel trans interactions among monomers. The structure illustrates how mechanistic unity is maintained on a chemical level while allowing for substantial variation on the structural level within a family of enzymes.

Amino Acid Sequence↗
PubMed2000

[Analyses on the association of CA-repeat polymorphism and A1166-->C variant in the 3'-flanking region of AT(1)R gene with essential hypertension in Tibetans].

OBJECTIVE: To investigate whether CA-repeat polymorphism and A1166 --> C variant in the 3n-flanking region of AT(1)R gene are in association with the genetic susceptibily to essential hypertension (EH) in Tibetans. METHODS: A case-control study was carried out. Sibpair analysis and family linkage analysis were conducted. The CA-repeat polymorphism of AT &(1) R gene was identified by polymerase chain reaction(PCR) with fluorescence labeled dCTP as substrate and by semi-automatic sequence technology. The A1166 -->C variant was detected by PCR-RFLP. RESULTS: Association of AT&(1)R gene locus with EH was confirmed through the case-control study in well-characterized group of 113 Tibetan EH patients and 131 normotensives(chi(2)=26.44, P<0.001). A closer examination of this gene locus found 11 alleles from Tibetan population; allele A7 (138 bp) was more frequent in both the patients and the controls. Allele A8(140 bp) was in strong positive association with genetic susceptibility to EH in Tibetans. Frequency of allele A8 was 20.5% in EH and 7.3% in normotensives. The difference of allele frequencies between the groups was significant (chi(2)=9.64, P=0.002, OR=3.46, 95% CI 1.44-8.51). Affected sibpair analysis showed chi(2)=3.85, P=0.025; family linkage analysis gave Lod score of 0.80. No association between A1166 --> C variant in AT(1)R gene and EH in Tibetans was observed (P>0.05). CONCLUSION: The result suggests that CA-repeat polymorphism of AT(1)R gene be in association with EH in Tibetans, which implicates that AT(1)R gene may be in linkage disequilibrium with the causative genes of EH.

Adult↗
PubMed2000

[Evaluation of immune prophylaxis of recombinant urease subunit of Helicobacter pylori].

OBJECTIVE: To evaluate the immune prophylaxis of recombinant urease subunit A or B (rUreA or rUreB). METHODS: The BALB/C mice were divided into seven groups: negative control group, control group with CTB, control group with rUreA, control group with rUreB, experimental group with rUreA + CTB and experimental group with rUreB + CTB, experimental group with sonicate + CTB, which were gastrically inoculated with 150 ml PBS, 5 micrograms CTB, 50 micrograms rUreA, 50 micrograms rUreB, 50 micrograms rUreA + CTB, 5 micrograms rUreB + CTB and 400 micrograms sonicate + 5 micrograms CTB, respectively. Two weeks later, the mice were gastrically infected with H. pylori (10(7)-10(8) CPU per time). 4, 8 and 12 weeks later, the mice were killed and the immune protection of PBS, CTB, rUreA, rUreB, rUreA + CTB, rUreB + CTB and sonicate + CTB were evaluated by the presence of H. pylori in gastric tissue stained with Giemsa by microscopy. The mice in the side-effecting groups of rUreA + CTB and rUreB + CTB were not infected with H. pylori. 12 weeks later, the mice in the two groups were killed, and the side effects of rUreA + CTB and rUreB + CTB were evaluated by the infiltration of inflammation cells in gastric tissue stained with HE by microscopy. RESULTS: The mice gastrically inoculated with CTB, rUreA or rUreB had significantly less H. pylori. The immune protective effect of rUreA, rUreB or sonicate of H. pylori combined with CTB was stronger than that of rUreA, rUreB or sonicate of H. pylori alone. The immune protective effect of rUreA + CTB occurred later than that of rUreB + CTB or sonicate of H. pylori + CTB. The mice immunized with rUreA + CTB, rUreB + CTB or sonicate of H. pylori + CTB were not completely protected against H. pylori infection. The mice immunized with rUreA + CTB, rUreB + CTB or sonicate of H. pylori + CTB were less infected with H. pylori, and had mild inflammation of gastric tissue. CONCLUSION: Mice immunized with rUreA + CTB, rUreB + CTB or sonicate of H. pylori + CTB could not be completely protected against H. pylori infection and have alleviated inflammation of gastric tissue.

Animals↗
PubMed2000

[The evaluation of cagA and other vaccine candidate proteins of Helicobacter pylori on T cell apoptosis mediated by Fas/Fas ligand interaction].

OBJECTIVE: To evaluate the effect of several surface proteins of Helicobacter pylori (H. pylori) on inducing apoptosis of T cells through the modulation of Fas/Fas ligand (FasL) interaction and to provide information on the screen of safe and effective immunogen for H. pylori vaccine. METHODS: T cell apoptosis induced by cagA+ and isogenic cagA knockout strain, recombinant urease, HpaA and outer membrane proteins, Hop25, Hop35 and Hop38 was detected by JAM assay. Flow cytometry was used to evaluate the increase in FasL expression on T cells under the stimulation of these bacterial proteins. Metalloprotease inhibitor, 1, 10-Phenanthroline (PHE) and protein synthesis inhibitor, emetine, were used to change the activity of FasL to confirm the association of FasL with H. pylori mediated killing toward T cells. RESULTS: The effect of cagA+ H. pylori was stronger in both the induction of apoptosis and FasL expression of T cells than that of cagA knockout strain. H. pylori urease could not kill T cell, while Hop38 had the strongest effect among the tested H. pylori proteins on the induction of T cell apoptosis through increasing FasL expression. Metaloprotease inhibitor could increase the killing of T cells induced by H. pylori because of its ability to prevent the cleavage of membrane-bound FasL protein. On the other hand, emetine could decrease H. pylori mediated killing by inhibiting of FasL synthesis on T cells. CONCLUSION: cagA and Hop38 protein might be involved in the negative regulation of T cell growth through upregulating FasL expression urease and other Hop proteins tested might be safe and effective to be used as the antigens for H. pylori vaccine.

Antigens, Bacterial↗
PubMed2000

[Effect of urotensin II on the airway smooth muscle cell proliferation and its mechanism].

OBJECTIVE: To investigate the effect and mechanism of Urotensin II on the airway smooth muscle cell proliferation. METHODS: (1) Using 3H-TdR incorporation to determine the effect of Urotensin II on the rat airway smooth muscle cells DNA synthesis. Different inhibitors were used to study the role of different signal transduction pathway such as protein kinase C (PKC), mitogen-activated protein kinase (MAPK), Calcineurin (CaN), Calmodulin-dependent protein kinase (CaM-PK) and calcium channel in the mitogenic effect of Urotensin II on the airway smooth muscle cells. (2) Using Fura-2/AM to measure the effect of Urotensin II on the cytosolic free calcium concentration. RESULTS: (1) Urotensin II (10(-10)-10(-6) mol/L) increased the airway smooth muscle cell 3H-TdR incorporation in a dose-dependent manner and Urotensin II 10(-6) mol/L reached the maximal effect. It was seven times as high as that of control (P < 0.01). (2) H7, PD98059, and nicardipine, inhibitors of PKC, MAPK and calcium channel, significantly inhibited Urotensin II (10(-7) mol/L)-stimulated airway smooth muscle cell 3H-TdR incorporation, with the inhibitory rate of 29% (P < 0.05), 45% (P < 0.01), and 28% respectively (P < 0.05). W7, an inhibitor of CaM-PK, had no effect (P > 0.05). (3) Cyclosporin A (10(-8)-10(-6) mol/L), inhibitor of CaN, an inhibited the airway smooth muscle cell 3H-TdR incorporation induced by Urotensin II (10(-7) mol/L) in a dose-dependent manner, with the inhibitory rate of 76% at 10(-6) mol/L (P < 0.01). (4) Urotensin II (10(-6) mol/L) promoted cytosolic free calcium concentration increase by 18% (P < 0.01). CONCLUSION: The effect of Urotensin II-stimulated airway smooth muscle cells DNA synthesis is mediated by Ca2+, PKC, MAPK and CaN signal transduction pathway.

Animals↗
PubMed2000

Clinical observation on the long-term therapeutic effects of traditional Chinese medicine for treatment of liver fibrosis.

48 patients with liver fibrosis due to hepatitis B were treated for 2 years with the drugs for tonifying the kidney, supplementing qi, cooling and invigorating the blood and detoxification. The symptoms were markedly improved, and serum ALT and bilirubin were recovered and kept normal in most of the cases. The mean levels of serum hyaluronic acid, procollagen peptide III and circulating immune complex were decreased and returned to normal after the treatment. B-ultrasonography showed that the portal vein kept in normal size in 82% of the patients, the enlarged portal vein diminished in diameter, and the enlarged spleen reduced.

Adult↗
PubMed2000

Sympathectomy induces novel purinergic sensitivity in sciatic afferents.

AIM: To test the hypothesis that sympathectomy could induce novel purinergic sensitivity in sciatic afferents. METHODS: Teased-fiber recordings were made from 32 spontaneously active A afferents from the sciatic nerves in surgically sympathectomized rats and 30 spontaneously active A afferents from the sciatic nerves in intact rats. Adenosine 5'-triphosphate (ATP) was injected via a cannula in jugular vein. RESULTS: Twenty eight percent of the spontaneously active afferent fibers from sciatic nerves in the sympathectomized rats responded to ATP, either with an increase or with a decrease in spontaneous firing. However, none of the fibers from the sciatic nerves in the intact rats was activated by ATP. CONCLUSION: Sympathectomy induces novel purinergic sensitivity in A afferents from sciatic nerve.

Adenosine Triphosphate↗
PubMed2000

[The expression level of the transfected hEGF gene to cultured human epidermal cells].

OBJECTIVE: To study the stable expression levels of cultured human epidermal cells transfected with a hEGF-plasmid. METHODS: The 60%-70% confluent cultured human epidermal cells were transfected with a pBK-Signal-EGF plasmid-construct mediated by lipofectAMINE. After screening of G418 successfully transfected, clone forming cells were picked and subcultured for several weeks. To detect hEGF expression levels and to determine long term transgenic stability a specific ELISA was used. RESULTS: (1) hEGF plasmid constructs were successfully introduced into cultured human epidermal cells. (2) Transgenic expression still persisted after four subcultures. (3) hEGF expression levels could be detected in the medium over a six-week period. CONCLUSIONS: The stable expression of hEGF was obtained after gene transfected with the pBK-Signal-EGF plasmid mediated by lipofectAMINE.

Cell Division↗
PubMed2000

[Effect of rhizospheric environment of VA-mycorrhizal plants on forms of Cu, Zn, Pb and Cd in polluted soil].

Maize (Zea mays L.) was inoculated with or without VA mycorrhizal (Glomus mosseae) and cultivated in a heavy metals contaminated soil. The distribution and dynamics of Cu, Zn, Pb and Cd forms in rhizosphere of maize inoculated with or without VA-mycorrhizal were analyzed with the technique of sequential extraction. Comparing with control soil, exchangeable Cu in rhizospheric soil increased significantly, and the exchangeable Cd trended down. In rhizosphere of VA-mycorrhizal maize, the amounts of Cu, Zn and Pb bound to organic matter were significantly higher than those in rhizosphere of non-mycorrhizal maize, while the four tested metals bound to carbonates and to iron and manganese oxides were constant in rhizosphere of mycorrhizal and non-mycorrhizal maize. These results illustrated that the plant roots could influence the distribution and dynamics of metal forms in rhizosphere, and much for mycorrhizal plants than for non-mycorrhizal plants. At excessive concentration of soil metals, mycorrhizal roots might decrease the bio-availability of toxic heavy metals by changing their forms. The factors that caused the change of metal fractions in rhizosphere of mycorrhizal and non-mycorrhizal plants were also discussed.

Cadmium↗