Biomedical subjects

Y Chen

Publications and source records attributed to Y Chen.

At least 577 records · Page 32Linked to original sources

PubMed2001

[Effects of TNF-alpha on IL-8 mRNA expression in endothelial cells].

As a kind of chemokine, IL-8 plays an important role in inflammatory reaction. Its expression in endothelial cells is regulated by a variety of cytokines. In this study, after incubating cultured human umbilical vein endothelial cells(HUVECs) with TNF-alpha for different time, we employed RT-PCR to assay IL-8 mRNA expression and immunocytochemical staining to detect NF-kappa B activation in HUVECs. The results revealed: (1) IL-8 mRNA expressed little in untreated HUVECs; after HUVECs was pre-incubated with TNF-alpha for 1 hour, IL-8 mRNA expression increased greatly, and it increased further after pre-incubated for 3 hours; however, when HUVECs was pre-incubated with TNF-alpha for 6 hours, IL-8 mRNA expression decreased, and it almost decreased to basal level when pre-incubated for 9 hours; (2) the immunoreactivity of NF-kappa B p65 in the nuclei of untreated HUVECs was negative; it became positive in the nuclei of HUVECs pre-incubated with TNF-alpha for 1 hour and 3 hours; it became weak positive in the nuclei of HUVECs pre-incubated with TNF-alpha for 6 hours, and after 9 hours, pre-incubation, the immunoreactivity of NF-kappa B p65 in the nuclei of HUVECs was negative. These results implied that TNF-alpha was capable of inducing IL-8 gene expression and activation NF-kappa B. and Their time courses were similar, thus suggesting that the induction of IL-8 gene expression by TNF-alpha is probably due to the activation of NF-kappa B.

Cells, Cultured↗

PubMed2001

[Effects of laminar shear stress on IL-8 mRNA expression in endothelial cells].

This study sought to demonstrate that IL-8 expression in endothelial cells is regulated by not only chemical factors but also mechanical factors. After pretreating cultured human umbilical vein endothelial cells (HUVECs) with shear stress for different periods of time, we employed RT-PCR to assay IL-8 mRNA expression and immunocytochemical staining to detect NF-kappa B activation in HUVECs. The results showed: 1. IL-8 mRNA expressed little in HUVECs untreated or pretreated with low laiminar shear stress for 0.5 h; IL-8 mRNA expression increased when HUVECs were pretreated with low laminar shear stress for 1 h, and it increased further when HUVECs were pretreated for 2 h; 2. The immunoreactivity of NF-kappa B p65 in the nuclei of HUVECs untreated or pretreated with low laminar shear stress for 0.5 h was negative, while it became weak positive in the nuclei of HUVECs pretreated with shear stress for 1 h and positive in the nuclei of HUVECs pretreated for 2 h. The findings implied that low laminar shear stress was capable of inducing IL-8 gene expression and activating NF-kappa B, which were both time-dependent. The induction of IL-8 gene expression by laminar shear stress is probably due to the activation of NF-kappa B. On these grounds we come to the conclusion that IL-8 expression induced in endothelial cells by low shear stress may play an important role in the genesis and development of both inflammation and arterioatherosclerosis.

Cells, Cultured↗

PubMed2001

[Correlation between liver fibrosis stage and serum liver fibrosis markers in patients with chronic hepatitis B].

OBJECTIVE: To evaluate the diagnostic value of serum liver fibrosis markers by analyzing the correlation between liver fibrosis stage in patients with chronic hepatitis B and serum liver fibrosis markers, such as hyaluronate, type III procollagen, laminin, and type IV collagen. METHODS: There were 278 patients with chronic hepatitis B in this series. Before liver biopsy, the serum was collected to test hyaluronate, type III procollagen, laminin, and type IV collagen. Data were analyzed statistically. RESULTS: Liver fibrosis stage was correlated to inflammation degree. In patients with moderate or serious liver inflammation and fibrosis, serum hyaluronate was above normal level, and correlated to liver inflammation and fibrosis. For patients with chronic hepatitis B, serum type III procollagen, laminin, and type IV collagen increased apparently. While laminin was correlated to liver fibrosis, type III procollagen and type IV collagen correlated to liver inflammation. CONCLUSIONS: Serum hyaluronate, type III procollagen, laminin, and type IV collagen could reflect the state of liver fibrosis. Hyaluronate may be a useful marker for liver cirrhosis.

Adolescent↗

PubMed2001

Expression, purification, and MALDI analysis of RPE65.

PURPOSE: RPE65 is preferentially expressed in the retinal pigment epithelium (RPE) and is essential for retinal function. The purpose of the study was to develop methods for the expression of the protein, determine the accurate molecular weight of this expressed protein, and quantitate the amount of RPE65 in the bovine RPE. METHODS: Human RPE65 was expressed in Sf9 cells using the baculovirus system. The subcellular localization was determined by Western blot analysis and immunocytochemistry. An ELISA was developed for RPE65 and used to measure levels in bovine RPE. Recombinant and native RPE65 were purified by affinity chromatography. Molecular mass was determined by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. RESULTS: Recombinant human (rH)RPE65 was expressed as a major protein associated with cell membrane in Sf9 cells. The recombinant protein was purified to apparent homogeneity from both the membrane and nonmembrane fractions. The identity of the purified protein was confirmed by Western blot analysis and by partial peptide sequencing. rHRPE65 from the nonmembrane fraction has a mass of 64,867 +/- 80 which is close to the calculated molecular weight from the amino acid sequence including the His-tag (64,663), whereas the membrane-associated rHRPE65 has a molecular mass of 65,380 +/- 150, which is significantly higher than that of the non-membrane-associated form and the calculated molecular weight, suggesting posttranslational modifications. Similarly, native RPE65 was detected in the cytosolic and microsomal fractions of the bovine RPE, with an average level of 3.8 +/- 1.3 and 7.2 +/- 0.4 microg RPE65 per eye, respectively. The cytosolic form had a molecular mass of 61,161 +/- 60, which is close to the calculated value (60,944), whereas that of the microsomal form was 61,961 +/- 170. CONCLUSIONS: RPE65 is expressed in two forms, one of which is membrane associated and contains significant posttranslational modifications, similar to the native membrane-associated form.

Animals↗

PubMed2001

[Evaluation for the regeneration efficiency of activated carbon by wet air oxidation].

It is well known that different regenerating techniques of activated carbon(AC) require the suitable evaluating methods for regeneration efficiency. In this paper, several methods for evaluating the regeneration efficiency of AC were compared and discussed by wet air oxidation(WAO) which were respectively based on different experimental protocols such as iodine value, molasses color adsorption, breckthrough profile, adsorption isotherm and standard reload experiment. The iodine value, molasses color adsorption and breckthrough profile yielded indefinitely PR values for WAO process, so they could not be applied to evaluate regeneration efficiency. And adsorption isotherm experiment was more correct because it compared isotherm loadings at the same equilibrium liquid phase concentrations, but this more laborious and time-consuming method was difficult to be widely used. The results also showed that the standard reload experiment was consequently picked out, easy to use and had high sensibility alternative to adsorption isotherm experiment. When controlling the WAO parameters at 250 degrees C, 0.6 MPa and 1 h, the regeneration efficiency arrived to 55%.

Air↗

PubMed2001

Perforated peptic ulcer in an infant.

We describe a case of perforated peptic ulcer (PPU) in a 9-month-old boy. Abdominal distension was the first clinical sign of PPU. Before he developed abdominal distension, the patient had suffered from an upper respiratory tract infection with fever for about 2 weeks, which was treated intermittently with ibuprofen. A plain abdominal radiograph revealed pneumoperitoneum with a football sign. At laparotomy, a 0.8-cm perforated hole was found over the prepyloric area. Simple closure with omental patching was performed after debridement of the perforation. Pathologic examination showed chronic peptic ulcer with Helicobacter pylori infection. The postoperative course and outcome were satisfactory. The stress of underlying disease, use of ibuprofen, blood type (A), and H. pylori infection might have contributed to the development of PPU in this patient. PPU in infancy is rare and has a high mortality rate; early recognition and prompt surgical intervention are key to successful management.

Humans↗

PubMed2001

[Study on the relationship between methylenetetrahydrofolate reductase gene C677T mutation and coronary heart disease].

OBJECTIVE: To investigate whether methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism is linked with coronary heart disease (CHD). METHODS: Transmission/disequilibrium test(TDT), sib transmission/disequilibrium test(STDT), and sibship disequilibrium test(SDT) were used. Forty-five CHD pedigrees with at least one CHD patient in the first degree relatives of probands were recruited from Oct. 1998 to Feb. 1999. Among those recruited were 21, 2 and 22 pedigrees with the genotypes of both parents known, one parental genotype unknown and both unknown, respectively. MTHFR genotype was measured by PCR-RFLP technique. RESULTS: Neither the TDT for 23 nuclear families with at least one parental genotype known or the STDT and SDT for 40 sibships found significant difference between the transmitted and untransmitted MTHFR gene 677T allele distributions. CONCLUSION: The above results suggest that MTHFR gene 677T allele is probably not linked with CHD in Chinese population.

Coronary Disease↗

PubMed2001

[Lignans from Schisandra propinqua (Wall.) Hook. f. et Thoms].

Three dibenzocyclooctadiene lignans were isolated from the stems of Schisandra propinqua (Wall.) Hook.f.et Thoms. Their structures were identified as interiotherin A (I), benzoylisogomisin O (II) and gomisin G (III) by spectroscopic analysis. Compound I was first discovered in Schisandra genus. Compounds II and III were originally isolated from S. propinqua.

Lignans↗

PubMed2001

Nitric oxide induces murine thymocyte apoptosis by oxidative injury and a p53-dependent mechanism.

Previously, we showed that NO induces thymocyte apoptosis via a caspase-1-dependent mechanism [(1) ]. In the present study, we investigated the role of heme oxygenase, catalase, bax, and p53 in this process. The NO donor, S-nitroso-N-acetyl penicillamine (SNAP), induced DNA fragmentation in thymocytes in a time- and concentration-dependent way. SNAP (100 microM) induced 50--60% apoptosis; higher doses did not increase the rate of apoptosis significantly. SNAP decreased catalase and heme iron (Fe) levels without affecting superoxide dismutase, glutathione, or total Fe stores in thymocytes. SNAP significantly increased the expression of heme oxygenase 1 (HSP-32), p53, and bax but not bcl-2. Treatment with the heme oxygenase inhibitor, tin protoporphyrin IX inhibited SNAP-induced thymocyte apoptosis. Furthermore, thymocytes from p53 null mice were resistant to NO-induced apoptosis. Our data suggest that NO may induce its cytotoxic effects on thymocytes by modulating heme oxygenase and catalase activity as well as up-regulating pro-apoptotic proteins p53 and bax.

Animals↗

PubMed2001

[Effect of flow shear stress on the expression of adhesion molecules of endothelial cells].

Adherence of various leukocytes, including monocyte, to vascular endothelial cells may play an important role in the development of atherosclerosis. In vivo, the hemodynamic shear forces have a critical effect on the surface expression of adhesion proteins. In order to elucidate the effect of flow shear stress on the expression of adhesion molecules of endothelial cells, we investigated the effect of flow shear stress (2.23-6.08 dyne/cm2) on the expression of adhesive molecules, intercellular adhesion molecule(ICAM-1), vascular cell adhesion molecule (VCAM-1), and E-selectin on cultured human umbilical vein endothelial cells(HUVECs). The expression of adhesion molecules on the surface of HUVECs induced by shear stress was analyzed using flow cytometry. The results showed that compared with stationary control, the surface expression of ICAM-1 was significantly increased (P < 0.05) on HUVECs after exposure to different shear stress (2.23, 4.20, 6.08 dyne/cm2), and it was found to be in close relationship with the shearing time (r = 0.992, 0.997, 0.997; P < 0.05). After exposure to shear(2.23 dyne/cm2), VCAM-1 expression was significant increased(P < 0.05), and it was positively correlated with the shearing time(r = 0.930; P < 0.05), while VCAM-1 expression dropped down to basal level(P < 0.05) after it was sheared at 4.20 or 6.08 dyne/cm2, and the magnitude of the reduction of VCAM-1 expression was negatively correlated with the shearing time (r = -0.975, -0.989; P < 0.05). E-selectin expression was less sensitive to shear stress, especially at the lower magnitudes of shear. These results indicate that the increase of ICAM-1 and VCAM-1 expression in endothelial cells induced by low shear stress may play a prominent role in the development of both inflammation and atherosclerosis.

Cells, Cultured↗

PubMed2001

[Relationship between methylenetetrahydrofolate reductase gene polymorphism and diabetic nephropathy].

OBJECTIVE: To investigate the relationship between methylenetetrahydrofolate reductase(MTHFR) gene polymorphism and diabetic nephropathy(DN). METHODS: The technology of polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) was used to detect MTHFR gene C677T mutation in 85 healthy controls, 79 type-2 diabetics without DN, and 82 type-2 diabetics with DN confirmed by urine microalbuminous detection. RESULTS: The frequencies of MTHFR gene variant genotypes and alleles in the patients with DN patients were significantly higher than those in the patients without DN and those in healthy controls (P<0.01). CONCLUSION: MTHFR gene C677T mutation is probably one of the genetic risk factors for diabetic nephropathy in Chinese Hans.

Asian People↗

PubMed2001

[The inhibitory effect of oxymatrine on hepatitis C virus in vitro].

OBJECTIVE: To study the inhibitory effect of oxymatrine on HCV in vitro. METHODS: SMMC-7721 cells transfected with pBK-HCV using lipofectin transfection protocal were treated with oxymatrine. bDNA signal amplification assay and MTT colorimetric assay were used for intracellular HCV RNA and cytotoxicity. RESULTS: The stable HCV expression cell model established here could be used as a tool for medicine screen. Oxymatrine at the concentration of 100~1000 mug/ml could significantly decrease the level of intracellular HCV RNA. No cytotoxicity was shown in such concentrations. CONCLUSIONS: Oxymatrine has an anti-HCV potential activity in vitro.

Alkaloids↗

PubMed2001

[Effect of Xue Zhi Kang on the formation of fatty liver in cholesterol-fed rabbits].

OBJECTIVE: To explore the effect of Xue Zhi Kang (XZhK) on the formation of fatty liver in cholesterol-fed rabbits. METHODS: XZhK was refined from Chinese traditional medicine Hong Qu and its main composition is HMG-CoA reductase inhibitor. Thirty New Zealand white rabbits were randomly assigned into 3 groups (control, hypercholesterol-fed, and XZhK groups) during the 12 week's experiment. The effects of XZhK (0.8g.kg(-1).d(-1)) were investigated in rabbits fed a l.5% cholesterol diet. The changes of serum TC, TG, HDL-C, and LDL-C concentrations and the histopathological changes of the liver were detected. RESULTS: The serum TC, LDL-C, and TG levels decreased in XZhK group compared with those in the cholesterol-fed control group (P<0.05 ). The serum HDL-C concentration slightly increased, but there was no statistical significance. The fatty degeneration of liver was ameliorated in XZhK group (P<0.05). CONCLUSIONS: XZhK can modulate the lipid metabolism and inhibit the formation of fatty liver in cholesterol-fed rabbits.

Animals↗

PubMed2001

[Production of transgenic lamb integrated with modified human anti-trypsin gene].

This experiment is to produce the human mAAT(modified anti-trypsin) which cures the emphysema specifically through mammalian galactophore of transgenic goat. 56 goats were selected as donor for superovulation by FSF + LH microinjection in this experiment. The pronucleic embryos were injected with human mAAT gene after fertilization in vivo, and transferred to the donors or receptors directly. The superovulation was better in March and May than in December with the number of ovulation of 19.50, 21.70 and 16.06, and number of fertilized embryos of 4.31, 6.48 and 3.57 per-animal respectively. The pregnant rates were 18.18% and 25% respectively after transferred to donors and receptors with natural estrus. The donors also can be used as the embryo receptor with no remarkable decrease of pregnant rate. 29 lamb were labored. 4 positive transgenic lamb were checked by PCR, PCR-Southern and Southern analysis. The integrated efficiency of foreign DNA was 13.79% with microinjection of high copy number of foreign DNA fragment.

Animals↗

PubMed2001

[The association between SA gene and essential hypertension in Han Chinese].

OBJECTIVE: To evaluate the linkage of SA gene locus to essential hypertension(EH) in affected Han Chinese sib pairs and to ascertain the association of SA gene CT79 polymorphism with essential hypertension in Han Chinese hypertensives. METHODS: In Han Chinese at Shanghai, 96 random individuals, 80 essentially hypertensive sib pairs with hypertensive family history, 200 essential hypertensives with hypertensive family history and 200 normotensive control(NC) subjects without such family history were enrolled in these serial studies. MF-PCR-SSCP technique was applied to detect the frequency distributions of SA gene microsatellite D16S3046, D16S3136 and D16S3068. The linkage of SA gene locus to essential hypertension was analyzed by Green's IBS for affected siblings. SA gene variant was screened by PCR-SSCP- silver staining and confirmed by DNA sequencing, then an association study was performed to determine whether such variant was associated with essential hypertension. RESULTS: The frequency distributions of SA gene microsatellites D16S3046, D16S3136 and D16S3068 were of high polymorphism. The polymorphism information contents of D16S3046, D16S3136 and D16S3068 were 0.86, 0.82 and 0.80, and the heterozygosities 0.88, 0.71 and 0.77. The linkage of SA gene locus to essential hypertension was not observed; the linkage analysis t values of D16S3046,D16S3136 and D16S3068 were 0.972, 0.622 and 0.236, and the P values 0.384, 0.543 and 0.871, respectively. The C two head right arrow T substitution was confirmed, but there was no association of such variant with essential hypertension. The frequency distributions of genotypes and alleles in the hypertensive group were not significantly different from those in the normotensive group (P>0.05). CONCLUSION: SA gene is not linked to or associated with essential hypertension in Han Chinese. SA gene may not be a susceptible gene contributing to the development of essential hypertension in Han Chinese.

Adult↗

PubMed2001

[Experimental study on the effect of combination therapy with lamivudine and famciclovir against duck hepatitis B virus in vivo].

OBJECTIVE: To study the antiviral effect of combination therapy with the nucleoside analog lamivudine and famciclovir on duck hepatitis virus (DHBV) in vivo. METHODS: The Chongqing duck hepatitis B model was treated with lamivudine and famciclovir by intragastric administration for 4 weeks. DHBV DNA and DHBsAg in serum were observed by serum dot-blot hybridization and ELISA. ALT and AST in serum were also detected. Histological observation on the duck liver was done simultaneously. The trial was contrasted with a single acyclovir (ACV), famciclovir (FCV), or Lamivudine (3TC). RESULTS: Combination therapy with Lamivudine and famciclovir could significantly reduce the serum DHBV DNA level. After stopping the treatment for 1 week, serum DHBV DNA level did not return significantly. The change of DHBsAg was similar to DHBV DNA. The level of ALT, AST, and the features of liver histopathology in combination-treated ducks were not different from those in control ducks. CONCLUSIONS: The study confirms that combination therapy is superior to single antiviral agent in vivo for ducks with chronic DHBV carrier.

2-Aminopurine↗

PubMed2001

[Preparation and identification of activity of antiplatelet-derived growth factor receptor beta subunit hammerhead ribozyme in vitro].

OBJECTIVE: To study the preparation and cleavage activity of ribozyme directed against platelet-derived growth factor (PDGF) receptor beta subunit gene transcript in vitro. METHODS: PDGF receptor B subunit gene fragments were cloned into T-vector under the control of T7 promotor. 32P-labeled PDGF receptor beta subunit transcripts as target-RNAs were transcribed in vitro and purified by PAGE. Ribozyme gene designed by computer targeting the extracellular domain was cloned into vector P1.5 between 5'-cis ribozyme and 3'-cis ribozyme. 32P-labeled ribozyme transcripts was gel-purified, incubated with target-RNAs at different conditions and autoradiographed after denaturing gel-electrophoresis. RESULTS: The preparation of ribozyme was correct. It was active at 37 degrees C. The optimal temperature was 50 degrees C, Km=13,20 nm, Kcat=0.28 min-1. The cleavage efficiency was up to 78.3%. CONCLUSIONS: Ribozyme prepared in vitro possesses specific catalytic activity.

Animals↗

PubMed2001

Spatial learning deficits in amyloid precursor protein 770 transgenic mice.

OBJECTIVE: To determine whether learning deficits could be seen in transgenic mice expressing human amyloid precursor protein 770 (APP770). METHODS: Female heterozygous transgenic and nontransgenic mice aged 3, 6 and 9 months at the start of testing were used, with eight mice in each age group. All mice were subjected to various behavioral tasks including the Y-maze task and the Morris water maze. After behavioral testing, the mice were sacrificed, and their brain tissues were used for measuring the choline acetyltransferase (ChAT) activity. RESULTS: Nine-month-old transgenic mice exhibited spatial learning deficits in the Morris water maze and in spontaneous alternation in the Y-maze, compared with those of the age-matched non-transgenic mice. The behavioral changes accompanied a reduction of ChAT activity in the cortical and hippocampal regions of transgenic mice. On the other hand, these behavioral deficits were not observed in transgenic mice either at 3 or at 6 months of age, in which ChAT activity remained unchanged. CONCLUSIONS: The present results show that the learning impairment observed in 9-month-old APP770 transgenic mice are accompanied by a decrease in cortical and hippocampal ChAT activities. This suggests that cholinergic deficits may be involved in the learning impairment observed in these APP770 mice. This model will be a useful tool in advancing our understanding of the relationship between the cholinergic system and the cognitive deficits observed in Alzheimer's disease (AD).

Amyloid beta-Protein Precursor↗