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Biomedical subjects

Zhi Chen

Publications and source records attributed to Zhi Chen.

At least 91 records · Page 5Linked to original sources
PubMed2004

Investigation on apoptosis of neuronal cells induced by Amyloid beta-Protein.

OBJECTIVE: To construct a PC12 cell strain with neuronal differentiation, and observe the apoptosis and proliferation activity effects induced these cells by Amyloid beta-Protein (Abeta-43). METHODS: 1) PC12 cells in logarithmic growth phase were subcultured for 24 h. After the culture fluid was changed, the cells were treated with Rat-beta-NGF and cultured for 9 days. 2) Neuronal differentiation of PC12 cells in logarithmic growth phase were divided into four groups: control group (0), experimental group (1), experimental group (2) and experimental group (3). The concentrations of Abeta in the four groups were 0 micromol/L, 1.25 micromol/L, 2.5 micromol/L and 5 micromol/L, respectively. The cells were harvested at 24, 48 and 72 h later and stained with AnnexinV-FITC/PI after centrifugation and washing. Then flow cytometry was conducted to examine the apoptosis percentage. 3) NGF-induced PC12 cells were selected and Abeta with different concentrations was added. The final concentrations of Abeta were 0 micromol/L, 1.25 micromol/L, 2.5 micromol/L and 5 micromol/L, respectively. After the cells were incubated in an atmosphere of 5% CO2 at 37 degrees C in an incubator for 72 h, the OD values were examined. RESULTS: 1) Neuronal differentiated PC12 cell lines were successfully established. 2) Flow cytometric examination indicated that Abeta (1.25, 2.5, and 5.0 micromol/L) could effectively induce apoptosis of neuronal-differentiated cells at the 24 h, 48 h and 72 h time points. 3) Abeta (0-5.00 micromol/L) had no obvious effect on proliferation or restraining of the neuronal differentiation of the PC12 cells after a 72 h interacting process. CONCLUSION: This investigation revealed successful neuronal differentiation of the PC12 cell strain. The induction of apoptosis of the neurocytes by various concentrations of Abeta was observed and the influence of Abeta on induced proliferation of PC12 cells by Rat-beta-NGF was revealed. This study may provide basis for future research on the molecular cure of AD and interdiction of AD evolution.

Amyloid beta-Peptides↗
PubMed2004

The modulation of thymosin alpha 1 in the maturation, differentiation and function of murine bone marrow-derived dendritic cells in the absence or presence of tumor necrosis factor-alpha.

Thymosin alpha 1 (Talpha1) has immunomodulatory effects on T-cells, NK-cells and macrophages, but its action on dendritic cells (DCs), which are recognized as the sole professional antigen presenting cells (APCs) capable of priming naïve T-cells, is poorly understood. In this study, the effect of Talpha1 in vitro on murine bone marrow-derived DCs (BMDCs) maturation, differentiation, and function with or without tumor necrosis factor-alpha (TNF-alpha), which is one of the important inflammatory parameters, has been investigated. We have shown, through flow cytometry, ELISA and mixed leukocyte reaction (MLR), that Talpha1 promoted CD4-expressed DC differentiation and the expression of activation markers, but did not influence IL-12 production and T cell-stimulatory capacity of DCs in the absence of TNFalpha during BMDCs maturation. Furthermore, in the presence of TNF-alpha, Talpha1 has been shown not only to promote the expression of CD4 on MHC class II+ DCs and enhance the up-regulated levels of mature markers induced by TNF-alpha, but also to suppress the up-regulated IL-12 production. Particularly, thus effects seen were obvious at pharmacological Talpha1 concentrations. However, Talpha1 did not inhibit TNF-alpha-induced T-cell stimulating function of DCs. This is the first reported example of a direct Talpha1-DC interaction and suggests a mechanism by which Talpha1 may in part affect T-cell responses by acting at the DC level and it may play an important role in the modulation of the local inflammatory responses in vivo.

Adjuvants, Immunologic↗
PubMed2004

Non-random fluctuations and multi-scale dynamics regulation of human activity.

We investigate if known extrinsic and intrinsic factors fully account for the complex features observed in recordings of human activity as measured from forearm motion in subjects undergoing their regular daily routine. We demonstrate that the apparently random forearm motion possesses dynamic patterns characterized by robust scale-invariant and nonlinear features. These patterns remain stable from one subject to another and are unaffected by changes in the average activity level that occur within individual subjects throughout the day and on different days of the week, since they persist during daily routine and when the same subjects undergo time-isolation laboratory experiments designed to account for the circadian phase and to control the known extrinsic factors. Further, by modeling the scheduled events imposed throughout the laboratory protocols, we demonstrate that they cannot account for the observed scaling patterns in activity fluctuations. We attribute these patterns to a previously unrecognized intrinsic nonlinear multi-scale control mechanism of human activity that is independent of known extrinsic factors such as random and scheduled events, as well as the known intrinsic factors which possess a single characteristic time scale such as circadian and ultradian rhythms.

Adult↗
PubMed2004

Within-person variability of urinary 6beta-hydroxycortisol to urinaryl ratios in Caucasian women.

Cortisol is metabolized to 6beta-hydroxycortisol by human cytochrome p450-3A4 (CYP3A4), an important enzyme involved in the metabolism of a variety of exogenous and endogenous compounds. Both cortisol and 6beta-hydroxycortisol are excreted in urine, and the ratio of these steroids has been proposed as an indicator of CYP3A4 activity. We evaluated within-person variability of this biomarker in 10 healthy Caucasian women, aged 23-58 years. Each study participant was asked to provide a fasting morning urine sample once a week consecutively for 8 weeks. Urinary cortisol and 6beta-hydroxycortisol were determined by immunoassay kits purchased from the DiaSorin (Stillwater, MN) and the Stabiligen (Nancy, France), respectively. The coefficients of variation (CV) of urinary 6beta-hydroxycortisol to cortisol ratios from study participants ranged from 16.7 to 51.4% (mean, 31.1%) over the study period. The level of the ratio measured in any single urine sample was correlated reasonably well with the average of the ratios over the 8-week study period from the same woman, with the mean correlation coefficient of 0.79. These results indicated that urinary 6beta-hydroxycortisol to cortisol ratios measured in a spot urine sample may reflect the level of this biomarker over a relatively longer time period in Caucasian women, and thus, it can be used in epidemiologic studies as a biomarker to evaluate the association between CYP3A4 activity and disease risk.

Adult↗
PubMed2004

Telomerase reverse transcriptase (hTERT) mRNA and telomerase RNA (hTR) as targets for downregulation of telomerase activity.

Telomerase is expressed in cancer cells but not in most normal cells, leading to the hypothesis that telomerase inhibitors may be a powerful approach to cancer therapy. It is possible that telomerase plays roles in the cell other than telomere elongation and that blocking telomerase expression may have consequences that differ from simply blocking the active site through competitive inhibition. Here, we test this hypothesis by comparing the effects of antisense oligonucleotides and small interfering RNAs (siRNAs) that target the telomerase reverse transcriptase (hTERT) mRNA with the effects of oligonucleotides that target the telomerase RNA component (hTR). We find that the use of anti-hTR oligomers is more effective in blocking telomerase expression than strategies that target hTERT mRNA. Anti-hTR compounds are active on addition to cells in the absence of lipid, whereas antisense oligonucleotides are not. The modest inhibition of hTERT expression caused by antisense oligonucleotides or siRNAs does not persist, suggesting development of resistance. These data suggest that strategies for telomerase inhibition that require downregulation of hTERT mRNA may be less straightforward than those that target hTR. In addition, we have not seen evidence for a role for hTERT other than in telomere maintenance.

Breast Neoplasms↗
PubMed2004

Enhancing cellular immune response to HBV M DNA vaccine in mice by codelivery of interleukin-18 recombinant.

OBJECTIVE: To investigate the effect of interleukin-18 (IL-18) on immune response induced by plasmid encoding hepatitis B virus middle protein antigen and to explore new strategies for prophylactic and therapeutic HBV DNA vaccines. METHODS: BALB/c mice were immunized with pCMV-M alone or co-immunized with pcDNA3-18 and pCMV-M and then their sera were collected for analysing anti-HBsAg antibody by ELISA; splenocytes were isolated for detecting specific CTL response and cytokine assay in vitro. RESULTS: The anti-HBs antibody level of mice co-immunized with pcDNA3-18 and pCMV-M was slightly higher than that of mice immunized with pCMV-M alone, but there was not significantly different (P>0.05). Compared with mice injected with pCMV-M, the specific CTL cytotoxity activity of mice immunized with pcDNA3-18 and pCMV-M was significantly enhanced (P<0.05) and the level of IFN-Gamma in supernatant of splenocytes cul-tured with HBsAg in vitro was significantly elevated (P<0.05) while the level of IL-4 had no significant difference (P>0.05). CONCLUSION: The plasmid encoding IL-18 together with HBV M gene DNA vaccines may enhance specific TH1 cells and CTL cellular immune response induced in mice, so that IL-18 is a promising immune adjuvant.

Animals↗
PubMed2004

[Effect of fragile histidine triad gene on apoptosis of MGC-803 gastric cancer cells].

OBJECTIVE: To investigate the effect of fragile histidine triad (FHIT) gene on the apoptosis of gastric cancer cells. METHODS: FHIT gene was transfected into gastric cancer cell line MGC-803 by liposome. Western blot and immunohistochemical assay were employed to detect the expression of FHIT. Apoptosis and cell cycle were analyzed by flow cytometry (FCM). Morphological changes were observed by light and electron microscope. RESULTS: Stable expression of FHIT protein in transfected MGC-803 cells was obtained. The rates of G0/G1 phase and apoptosis cells were significantly higher in FHIT-transfected MGC-803 cells than those in control cells (64.4%compared with 49.5%and 32.0%compared with 12.2%, respectively). CONCLUSION: The results indicate that FHIT gene might be involved in the apoptosis of gastric cancer cells.

Acid Anhydride Hydrolases↗
PubMed2004

[Development of a system for quick screening of efficient HBx-siRNA].

OBJECTIVE: To develop a system for quick screening of efficient siRNA targeted HBx mRNA. METHODS: Using recombination DNA technique, the fusion expression plasmid of HBx and EGFP was constructed, and siRNA expression cassettes (SECs) containing U6+1, H1 or tRNA(Val )promoter were prepared via one-step overlapping extension PCR. By co-transfection with recombinant plasmid and SECs into AD293 cell, the inhibition effects on the transient expression of HBx-EGFP fusion protein were analyzed by FACS and semi-quantitated RT-PCR analysis. RESULT: (1)HBx-EGFP fusion protein expression plasmid pHBx-EGFP was constructed successfully, which expressed green fluorescence in cell mainly located at plasma or the periphery of nucleus in granules. (2) Co-transfection with recombinant plasmid and SECs into AD293 cells resulted in inhibition of HBx-EGFP expression. SEC-siHBx388 showed significant inhibition effect on HBx-EGFP expression compared with SEC-siHBx271, indicating that siHBx388 is effective siRNA site and could be screened out with our screening system. In addition,the results of that U6+1-, tRNA(Val) and H1-siHBx388 reduced HBx-EGFP expression by 21.7%, 12.9% and 12.4% of control respectively indicated that both tRNAVal and H1 promoter was high efficient in driving effect of siHBx388. CONCLUSION: Combination of the HBx expression carrying reporter gene and PCR-based multi promoter SECs may develop a useful system to be applied in identification of optimal HBx- siRNA and its matching promoter.

Base Sequence↗
PubMed2004

Expression of IFN-gamma and its receptor alpha in the peripheral blood of patients with chronic hepatitis C.

BACKGROUND: It has been known that intra-cellular immunity is important for defense against viral infections and this function lies with interferon gamma (INF-gamma). Here we evaluated the role of IFN-gamma system in the pathogenesis of chronic hepatitis C (CHC). METHODS: The levels of interferon gamma receptor alpha (IFNGR alpha) on the peripheral lymphocyte membrane were assayed with flow cytometry. The plasma concentrations of the cytokines IFN-gamma and IL-10 in CHC patients and normal controls were assayed by enzyme-linked-immunosorbent assay (ELISA). The samples were collected randomly from Xinjiang Autonomous Region, Zhejiang and the northern regions of Jiangsu Province in China. RESULTS: The levels of IFNGR alpha in CHC patients were significantly lower than that of normal controls (NC), especially among patients during the stable stage (P < 0.001), whereas there were no significant differences between CHC in active and stable stages. Among the patients of the three regions, there were no significant differences between patients from Xinjiang and Zhejiang provinces, but both had statistically significant difference compared with the patients from Jiangsu Province (P < 0.001). Plasma IFN-gamma and IL-10 concentrations in CHC patients decreased significantly, IFN-gamma in particular, but there were no significant differences in these levels between various stages of the disease. The IFN-gamma/IL-10 (Th1/Th2) ratio in patients was reversed. CONCLUSION: There may be defects in the IFN-gamma system in chronic HCV infected subjects and a low immune response, which may play an important role in the persistence of HCV infection.

Adolescent↗
PubMed2004

[Preparation of cationic liposomes and its role in enhancing cellular uptake of antisense oligonucleotides].

AIM: To prepare the liposomes which protect antisense oligodeoxynucleotides (ASON) against nuclease degradation and delivery ASON into cytoplasmic efficiently. METHODS: A cationic derivative of cholesterol, 3 beta-[N-(N',N'-dimethylaminoethan)-carbamoyl] cholesterol (DC-Chol) was synthesized and used to prepare cationic liposome. The characteristics of liposomes/ASON complexes including size, drug loaded efficiency and structure were investigated. Cellular uptake of fluorescence labled ASON (FAM-ASON) under different condition was determined by flow cytometric analysis. Denatured polyacryamide gel electrophoresis (DPGE) was used to analyze the role of liposomes in protecting ASON. RESULTS: The mean values of preliposomes and liposomes/ASON complexes size were 185.7 and 228.2 nm, respectively. Cationic liposomes showed a high adsorption capacity for ASON. When the +/- charge ratio exceeded 2:1, more than 90% of the ASON was loaded into liposomes. Agarose gel electrophoresis showed three different existence of ASON in liposomes formulation: free, absorbed and encapsulated types. Concerning cellular uptake, DC-Chol liposomes indicated high efficient effect of increasing cellular uptake of ASON. Compared with free ASON, the total fluorescence intensity in cytoplasma was significantly enhanced. The level of increasing was largely depended on +/- charge ratio. The cellular uptake of FAM-ASON decreased in the presence of serum. The cellular total fluorescence intensity in 10% and 30% fetal bovine serum of cultured medium were only 22.3% and 15.5% as that of serum-free media, respectively. DPGE confirmed that free ASON was rapidly degraded by DNase I while ASON encapsulated into liposomes was efficiently protected. CONCLUSION: The cationic DC-Chol liposomes are shown to be promising carriers to deliver ASON into cytoplasma.

Cholesterol↗
PubMed2004

[Involvement of TRAIL up-regulation of CD4+, CD8+ T cells in liver injury in chronic hepatitis B].

OBJECTIVE: To describe a novel mechanism for TRAIL up-regulation of CD4+, CD8+ T cells to participate in the pathophysiological process in patients with chronic hepatitis B (CHB). METHODS: The serum levels of soluble TRAIL (sTRAIL), IFN-gamma and membrane bound TRAIL expression on peripheral leucocytes from 58 CHB patients were examined by ELISA and flow cytometry respectively. The levels of TRAIL were compared with the baseline levels of 15 healthy controls, and correlation analysis were performed between ALT, TBil and PT, morphological change in hepatic tissues. RESULTS: The results showed that TRAIL levels on membranes of CD4+, CD8+ T cells in CHB patients were much higher than the healthy controls (P < 0.001), which of CD4+ T cells positively correlated with serum TBil (r=0.354, P = 0.008), Serum IFN-gamma level (r=0.302, P = 0.011) and which of CD8+ T cells positively correlated with serum TBil (r=0.522, P = 0.000), ALT (r=0.393, P = 0.003), PT (r=0.385, P = 0.004), serum IFN-gamma level (r=0.307, P = 0.009). The serum levels of soluble TRAIL only correlated with serum HBeAg expression (r=0.695, P = 0.001). CONCLUSION: These findings suggest that the expression of TRAIL on the membranes of lymphocytes was up-regulated, which may take part in the immunopathogenesis in CHB patients. TRAIL expression can be induced either by virus-specific protein expression or by inflammation cytokine IFN-gamma

Adult↗
PubMed2004

[Enhancement of immune responses in rabbits with a targeted anti-caries DNA vaccine pGJA-P].

OBJECTIVE: To detect the immunoreactivity of targeted fusion anti-caries DNA vaccine pGJA-P in vitro, and the ability to enhance the immune responses compared with the non-targeted fusion anti-caries DNA vaccine pGLUA-P. METHODS: The CHO cells were transfected with pGJA-P and the expression of recombinant protein in cultured supernatants were detected using Western blotting. 5 to 6-month-old female Japanese rabbits were immunized with either pGJA-P or pGLUA-P via either intramuscular injection (i.m.) or intranasal route (i.n.). The sera and saliva were collected and the antibody responses were checked by ELISA. The effect of immune sera on the synthesis of water-insoluble glucan by glucosyltransferase of S. mutans was examined. RESULTS: The expressed protein could response to specific anti-GTF antibody. The antibody responses in serum generated by pGJA-P via i.m. were significantly higher than those generated by pGLUA-P (P < 0.01). The antibody responses in saliva generated by pGJA-P via i.n. were significantly higher than those generated by pGLUA-P (P < 0.01). The higher mucosal antibody response induced by pGJA-P via i.m. compared with pGLUA-P (P < 0.01) was detected. The immune sera of rabbits immunized by pGJA-P via i.m. most significantly inhibited the synthesis of water-insoluble glucan by glucosyltransferase. CONCLUSIONS: The recombinant protein expressed by pGJA-P had the immunoreactivity to anti-GTF antibody. pGJA-P could induce faster and higher specific mucosal SIgA antibody responses via i.n. or serum IgG antibody responses via i.m. compared with non-targeted DNA vaccine, pGLUA-P. High titres of specific mucosal antibodies were found in rabbits immunized with pGJA-P via i.m. The immune sera of rabbits immunized by pGJA-P via i.m. displayed the ability of inhibiting the synthesis of water-insoluble glucan by glucosyltransferase.

Animals↗
PubMed2004

Dural arteriovenous fistulae after forehead knife-cut injury.

Dural arteriovenous fistulae (DAVF) is a rare intracranial vascular disease. It is pathologically characterized by direct shunting of the intracranial artery and vein, which results in cerebral ischemia, intracranial hemorrhage, neural deficit and intracranial murmur. The etiological mechanism of DAVF is not well known, but most researchers think it is associated with congenital abnormal development, especially abnormal development of dural blood vessels at the stage of embryogenesis. Recently, some researchers have found that DAVF is also associated with some acquired factors. This article reports a case who developed DAVF within 2 years after debridement of frontal bone fragmentation, depressed fracture, left frontal lobe contusion and superior sagittal sinus injury due to forehead knife-cut injury. The pathogenic mechanism was explored through a review of the related literatures.

Adult↗
PubMed2004

[The clinical efficacy of hemoperfusion in treatment of drug poisoning].

OBJECTIVE: To investigate the ability of hemoperfusion to remove some drugs or toxin from the body and its clinical efficacy. METHODS: Sixty-nine cases of poisoning due to tetramine or other drugs poisoning in our hospital between July 1990 and December 2003 were studied. Thirty-four patients among them received conventional treatment (including early gastric lavage, hepatoprotection, diuresis or respiratory support), and the remaining were given conventional treatment and hemoperfusion. Toxin concentration changes in blood before and after hemoperfusion, survival rate, time from come onset to regaining consciousness and convulsion termination and duration of clinical course were compared. RESULTS: In the hemoperfusion group, three patients died, the survival rate was 91.4%, whereas in the non-hemoperfusion group, the survival rate was 85.3% (P > 0.05). Meanwhile the clinical course was markedly shortened in the hemoperfusion group (P < 0.05). The time from coma onset to regaining consciousness and convulsion termination in the hemoperfusion group was significantly shorter than that in the non-hemoperfusion group. The clearance rate was different for different poisons, among them the benzodiazepines had an excellent clearance. CONCLUSIONS: Hemoperfusion could adsorb from blood a different amount of poisons. There is obvious efficacy in shortening clinical course and reducing complications. It could possibly raise survival rate in serious poisoning.

Adolescent↗
PubMed2004

[Effect of chuanxiongzine on the relaxation of isolated rabbit corpus cavernosum tissues].

OBJECTIVE: To investigate the effects of chuanxiongzine on the relaxation of isolated rabbit corpus cavernosum tissues. METHODS: Observations were made on the relaxing effect of chuanxiongzine on phenylephrine (PE)-precontracted corpus cavernosum and cavernosal strips preincubated with L-NAME, and ODQ, using endothelium removal and experimental method of smooth muscle strips. The effect of chuanxiongzine on cAMP and cGMP levels in corpus cavernosum was measured by 125I radioimmunoassay. RESULTS: Chuanxiongzine had concentration-dependent relaxing effect on the cavernosal muscle contraction induced by PE (EC50 1.58 x 10(-4) mol/L). This relaxing effect was partially antagonized by ODQ and not blocked by L-NAME or endothelium removal. In PE-precontracted cavernosal strips, chuanxiongzine induced relaxation accompanied with an increase in cAMP and cGMP levels. CONCLUSION: Chuanxiongzine was effective in relaxing cavernosal muscle precontracted by PE in vitro. And its relaxing effect may be enhanced by increasing cGMP and cAMP levels in the corpus cavernosum.

Animals↗
PubMed2004

[Establish a screening system for selection of mRNA target sites for HBsAg to construct siRNA with shRNA].

OBJECTIVE: To find some effective short interfering RNA's sites targeting HBV surface gene sequence using shRNA expression vectors. METHODS: Four shRNA expression vectors targeting HBV surface gene sequence were constructed based on pAVU6 + 27 vector, and cotransfected into AD293 cells with HBs-EGFP fusion gene plasmid. The changes of HBs-EGFP image were detected by FACS and microscopy. The HBs-EGFP mRNA expression was evaluated by RT-PCR. RESULTS: Four shRNA expression vectors and HBs-EGFP fusion gene plasmid were successfully constructed. pAVU6 + 4sh579 vector inhibited the HBs-EGFP expression by 69.8% in AD293 and suppressed the HBs-EGFP mRNA expression by 74.6%. CONCLUSIONS: The results showed that the 579 site of HBV surface gene sequence was an effective target and pAVU6 + 4sh579 vector could suppress the HBs-EGFP expression in AD293 cells

Gene Expression Regulation, Viral↗
PubMed2004

[Construction and expression of plasmids containing different truncated core proteins of hepatitis C virus derived from tumor and non-tumor tissues].

OBJECTIVE: To study the role of different truncated core proteins (CORE) of hepatitis C virus (HCV) played in the pathogenesis of HCV persistent infection and hepatocellular carcinoma, and to construct seven different truncated prokaryotic expression plasmids of HCV CORE. METHODS: The gene sequences of different truncated HCV genotype 1b CORE were amplified from plasmids containing CORE sequences derived from tumor and non-tumor tissues of a patient infected with HCV. Amino acid (aa) lengths of HCV BT (from tumor tissue, patient B) were: 1-172 aa, 1-126 aa, 1-58 aa, 59-126 aa, 127-172 aa; of BNT (non-tumor tissue, patient B) were: 1-172 aa and HCV C191 (HCV-J6): 1-172 aa. PCR products were cleaved with restriction enzymes BamH I and EcoR I and cloned into pGEX-4T-1. Positive clones were transformed into BL21 and glutathione S-transferase(GST)-CORE fusion proteins were expressed with isopropylthio-beta-D-galactoside (IPTG) induction, purified and verified by Western blot. RESULTS: Different truncated GST-CORE fusion proteins were expressed with different quantities. Except the fragment of 59-126 aa, the longer the fragment, the less its expression. The levels of truncated expression of CORE of BT and BNT were higher than that of C191, even though they all contained 1-172 aa. Some of truncated CORE of HCV genotype 1b could form dimmers. CONCLUSIONS: Successful construction of truncated GST-CORE expression plasmids lays a basis for future study of the function of different domains of CORE of different HCV strains; different expression levels of HCV COREs might be related to their different hydrophobicity, cytotoxicity and their functions in HCV structure and their roles played in the pathogenesis; the domain of 59-126 aa is responsible for the HCV genotype 1b CORE dimmer formation.

Carcinoma, Hepatocellular↗