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Biomedical subjects

H Ren

Publications and source records attributed to H Ren.

At least 19 recordsLinked to original sources
PubMed2001

Different protective roles in vitro of alpha- and beta-domains of growth inhibitory factor (GIF) on neuron injuries caused by oxygen free radicals.

It was well known that beta-amyloid (Abeta) and tau protein play an important role in pathological procedure of Alzheimer's disease (AD), a senile dementia. The growth inhibitory factor (GIF, also named metallothionein-3, MT-3) had been demonstrated to inhibit the outgrowth of cortex neurons in the medium with extract of the AD patient brain. In our experiments, it was found that the neurons of cortex and the PC12 (pheochromocytoma) cells could be protected from the cytotoxicity of beta-amyloid 25-35 in presence of GIF and its domains. Additionally, GIF can scavenge the hydroxyl radical efficiently in CytC-VitC radical producing system and its alpha-domain shown more effective potentials than its beta-domain. The electron paramagnetic resonance spectra also show that the alpha-domain has more potential ability for eliminating reactive oxygen free radicals than its beta-domain. The results suggest that GIF could act as an efficient scavenger against free radicals in vitro and the alpha-domain in GIF molecule shows more potential in protecting against reactive oxygen species injury than the beta-domain.

Alzheimer Disease↗
PubMed2001

Amino acid sequence requirements of peptides that inhibit polyglutamine-protein aggregation and cell death.

Proteins with expanded polyglutamine domains cause eight inherited neurodegenerative diseases including Huntington's disease. In a previous paper, we identified peptides that inhibit polyglutamine protein aggregation and cell death and now describe the amino acid sequence requirements necessary for these activities. The original 11 amino acid polyglutamine (Q) Binding Peptide 1(QBP1; SNWKWWPGIFD) can be shortened to 8 amino acids (WKWWPGIF) without loss of ability to inhibit polyglutamine aggregation. Three determinants are responsible for inhibition: a tryptophan-rich motif (WKWW), a spacer amino acid and the tripeptide GIF. GIF can be replaced by a repeat of the tryptophan-rich motif, but the spacer remains necessary. We also demonstrate concordance between peptide activity in the in vitro assay and a cellular assay of polyglutamine aggregation and cell death. Polyglutamine binding peptides targeted for intracellular delivery by fusion to TAT retain the ability to inhibit polyglutamine aggregation and cell death in transfected COS 7 cells.

Amino Acid Sequence↗
PubMed2001

The superiority of organically cultivated vegetables to general ones regarding antimutagenic activities.

We found organically cultivated (OC) vegetables, using a water-soluble chitosan as a soil improvement agent and leaf surface spray, had much longer shelf life and better taste than that of generally cultivated (GC) vegetables. The purpose of this study is to determine the relative antimutagenic activity between OC and GC vegetables. Eleven OC vegetables were harvested in March and April in 1999 and 2000, and GC ones were supplied as a control from nearby farms on the same date. The former vegetables were planted on the field where no pesticide had been used for the last 3 years. Forward mutation test with Salmonella typhimurium TM677 and 8-azaguanine as a detection agent was used to determine the antimutagenic activity of juices prepared from OC and GC vegetables against authentic mutagens, such as 4-nitroquinoline oxide (4NQO), benzo(a)pyrene (BaP), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2). This microbiological test is a convenient method to use for the food samples containing free histidine. Antimutagenic activity was evaluated by the difference of mutagenic activities between mutagenecity of authentic compounds and that observed upon incubation at 37 degrees C for 2h with each vegetable juice. OC Chinese cabbage, carrot, Welsh onion, and Qing-gen-cai suppressed 37-93% of the mutagenic activity of 4NQO, while the GC ones were held down to 11-65%. Against BaP, three species of OC vegetables showed 30-57% antimutagenecity, while GC ones did only 5-30%. Similarly, the OC spinach decreased the activity of Trp-P-2 to 78%, and the GC suppressed it by 49%.

Animals↗
PubMed2001

Design, synthesis, and biological evaluation of a series of simple and novel potential antimalarial compounds.

A series of compounds bearing an endocyclic -N-O- moiety with potential antimalarial activity based on simple derivatives of the tropolone purpurogallin was prepared by means of a hetero Diels-Alder reaction using nitrosobenzene as a dienophile. The rationale behind the design of these compounds is presented, together with the synthetic route to derivatives bearing aromatic and aliphatic esters of the C4'-position hydroxyl group of the purpurogallin framework, as well as biological data obtained from in vitro assays against Plasmodium falciparum and Trypanosoma cruzi. Several of the new compounds have activities in the 3-9 microM range, and provide leads for the development of a novel class of antiparasitic drugs with improved biological and pharmacological properties.

Animals↗
PubMed2001

Diffusion coefficient of DNA molecules during free solution electrophoresis.

The free-draining properties of DNA normally make it impossible to separate nucleic acids by free-flow electrophoresis. However, little is known, either theoretically or experimentally, about the diffusion coefficient of DNA molecules during free-flow electrophoresis. In fact, many authors simply assume that the Nernst-Einstein relation between the mobility and the diffusion coefficient still holds under such conditions. In this paper, we present an experimental study of the diffusion coefficient of both ssDNA and dsDNA molecules during free-flow electrophoresis. Our results unequivocally show that a simplistic use of Nernst-Einstein's relation fails, and that the electric field actually has no effect on the thermal diffusion process. Finally, we compare the dependence of the diffusion coefficient upon DNA molecular size to results obtained previously by other groups and to Zimm's theory.

Algorithms↗
PubMed2001

Short-chain fatty acids induce intestinal epithelial heat shock protein 25 expression in rats and IEC 18 cells.

BACKGROUND & AIMS: Because short-chain fatty acids (SCFAs) and heat shock proteins (hsps) confer protection to intestinal epithelia cells (IECs), we studied whether SCFAs modulate IEC hsp expression. METHODS: Hsp 25, hsp72, and hsc73 protein expression in rat intestinal tissues and IEC-18 cells were determined by Western blot and immunohistochemistry. Cell survival under conditions of oxidant stress (monochloramine) was determined using (51)Cr release in hsp25 cDNA anti-sense and sense-transfected cells expressing minimal and increased hsp25, respectively. RESULTS: Butyrate induces a time- and concentration-dependent increase in hsp25, but not hsp72 or hsc73, protein expression in rat IEC-18 cells but not 3T3 fibroblasts. Other SCFAs, including the poorly metabolized isobutyate, also induced selective expression of hsp25. Butyrate treatment significantly improved the ability of IEC-18 cells to withstand oxidant (monochloramine) injury. This effect could be blocked in cells in which hsp25 induction by butyrate was blocked by stable hsp25 antisense transfection. Additionally, hsp25-transfected overexpressing IEC-18 cells showed increased resistance to monochloramine. In vivo, increasing dietary fiber increased colonic, but not proximal, ileal hsp25 while having no effect on hsp72 or hsc73 expression. CONCLUSIONS: SCFAs, the predominant anions of colonic fluid derived from bacterial flora metabolism of luminal carbohydrates, protect IECs against oxidant injury, an effect mediated in part by cell-specific hsp25 induction.

3T3 Cells↗
PubMed2001

Glutamine reduces cytokine release, organ damage, and mortality in a rat model of endotoxemia.

Clinical trials have demonstrated that glutamine (GLN) supplementation can decrease infectious morbidity and improve survival in a number of settings of critical illness. The mechanism of this protection remains unclear. The objective of this study was to evaluate the effect of GLN on cytokine release, organ injury, and survival from endotoxin-induced septic shock. Endotoxemia was induced in Male Sprague-Dawley rats by intravenous administration of 5 mg/kg Escherichia coli lipopolysaccharide (LPS). Concomitantly, animals were fluid resuscitated with a lactated ringers (LR) solution and given GLN (0.75 g/kg i.v.) or LR alone. Blood samples were obtained at multiple time points post-LPS injury for cytokine analysis. Survival rates were monitored for 72 h. Organ injury was evaluated in a separate set of animals via pathologic exam of tissues harvested 6 h post-LPS injury. A single dose of GLN significantly attenuated the release of TNF-alpha at 2 h (P < 0.005) and IL-1 beta at 4 h (P < 0.0001). This attenuation of cytokine release was associated with a significant decrease in mortality (P < 0.003). Pathologic exam demonstrated significant protection of both lung and small bowel tissue by GLN. Blood gas values 6-h post-LPS injury showed increased PaO2 and bicarbonate concentration in GLN treated animals. These data indicate that GLN can significantly attenuate pro-inflammatory cytokine release, protect against end-organ damage, and decrease mortality from endotoxemia. GLN confers protection even when administered at the onset of endotoxemia, rather then as pre-treatment. Thus, one explanation for the clinical benefits observed from GLN-supplementation may be related to the attenuation of pro-inflammatory cytokines.

Animals↗
PubMed2001

Glutamine induces heat shock protein and protects against endotoxin shock in the rat.

Enhanced expression of heat shock protein (HSP) has been shown to be protective against laboratory models of septic shock. Induction of HSPs to improve outcome in human disease has not been exploited because laboratory induction agents are themselves toxic and not clinically relevant. In this study, we demonstrate that a single dose of intravenous glutamine causes a rapid and significant increase in HSP25 and HSP72 expression in multiple organs of the unstressed Sprague-Dawley rat. With the utilization of a fluid-resuscitated rat model of endotoxemia, mortality was dramatically reduced by glutamine administration concomitant with the endotoxin injury. Endotoxin-treated animals given glutamine exhibited dramatic increases in tissue HSP expression and marked reduction of end-organ damage. These data suggest glutamine may protect against mortality and attenuate end-organ injury in endotoxemic shock via enhanced HSP expression. Furthermore, glutamine confers protection when administered at the initiation of sepsis, rather than as pretreatment. Thus glutamine appears to be a clinically viable enhancer of HSP expression and may prove beneficial in the therapy of sepsis and sepsis-induced organ injury.

Ammonia↗
PubMed2001

The effect of Bcl-2 adenovirus against murine hepatocyte apoptosis caused by tumor necrosis factor alpha and D-galactosamine.

OBJECTIVE: To evaluate the role of Bcl-2 family proteins in hepatic apoptosis caused by TNF-alpha and D-galactosamine. METHODS: We induced mouse liver injury with TNF-alpha and D-galactosamine, and detected hepatic apoptosis, the expression of Bcl-2, Bax, and Bak proteins on hepatocytes by using TUNEL or immunohistochemistry, respectively. We also observed the expression of Bcl-2 protein on hepatocytes infected with Bcl-2 adenovirus vector and its protection against hepatocyte apoptosis. RESULTS: Hepatocyte apoptosis was induced in BalB/c mice pretreated with TNF-alpha plus D-galactosamine, accompanying the enhanced expression of Bax, Bak proteins in hepatocytes. Bcl-2 protein was expressed in murine hepatocytes and lasted at least 1 month after injection of Bcl-2 adenovirus vector, which also lowered ALT level from (1372.9+/-251.4)U/L to (796.5+/-78.7)U/L and reduced hepatocyte apoptosis caused by TNF-alpha and D-galactosamine. CONCLUSIONS: The enhanced expression of Bax, Bak proteins may play a role in hepatocyte apoptosis induced by TNF-alpha and D-galactosamine. D-galactosamine adenovirus vector can partially reduced hepatocyte apoptosis induced by TNF- alpha and D-galactosamine.

Adenoviridae↗
PubMed2001

Hepatitis B virus transgenic mice for the model of anti-hepatitis B virus drug study.

OBJECTIVE: To establish hepatitis B virus (HBV) transgenic mice models and to investigate if the model can be used for the evaluation of anti-HBV drugs. METHODS: HBV transgenic mice models were produced by microinjection to analyze the integration, expression of HBV in the transgenic mice by nested PCR, southern blot, immunohistochemistry, and ELISA. Sixty mice whose HBV DNA, HBsAg were positive were divided into 6 groups randomly, in which 3 groups were given drugs: lamivudine administrated by perfusion of stomach tube (100mg x kg(-1) x day(-1) for 21 days); thymosine administrated by abdomen injection (3mg x day(-1) for 90 days); and DNA vaccine of 100 microg by muscle injection. The other 3 groups were negative control. RESULTS: Lamivudine, thymosine and DNA vaccine made HBV DNA become negative in the serum of HBV transgenic mice. The negative ratio was highest in lamivudine treatment group. HBV DNA became positive again when lamivudine terminated. CONCLUSION: Limvudine, thymosine, and DNA vaccine can inhibit HBV replication. Transgenic mice might be used as the model for anti-HBV drug screening and evaluation.

Animals↗
PubMed2001

[Recombinant human growth hormone downregulates the apoptosis of HepG(2) cells induced by LPS].

OBJECTIVE: To investigate the effect of LPS on human hepatocytes and study whether recombinant human growth hormone (rhGH) could protect hepatocytes from apoptosis induced by LPS. METHODS: HepG(2) cells were treated with LPS (20 microg/ml) or LPS and rhGH for 16 hours. The apoptosis of HepG(2) cells was detected by terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) or electron microscopy. RESULTS: HepG(2) cells treated with LPS exhibited some specific morphological features of typical apoptosis. the percentage of apoptotic cells in HepG(2) cells treated with LPS and hrGH was significantly lower than that treated with LPS (36+/-5.6)% vs (99+/-0.8)%, P<0.001). CONCLUSIONS: LPS can induce apoptosis of HepG(2) cells, and hrGH can downregulate the apoptotic role of LPS on HepG(2) cells.

Apoptosis↗
PubMed2001

[Humoral immunization and cell-mediated immunization evoked by HBsAg and B7-2 Ag coexpression recombinant adenovirus vector].

OBJECTIVE: To evoke cytotoxic T lymphocytes (CTL) response and seek for a more effective method to treat chronic hepatitis B. METHODS: The adenovirus vector was constructed with the foreign genes inserted in the early region 1(E1), which directed coexpression of HBV-S and B7-2 antigens by means of an internal ribosomal entry site placed between the two coding sequences. The vector was transfected into 293 cell lines by liposome and the adenovirus expressing the target antigens was obtained by plaque select. The HBsAg and B7-2 antigen expression in in vitro cell culture was measured by ELISA and Western blotting, respectively. The immune responses were measured by ELISA for antibody response and a LDH release assay for CTL activity after immunization with the recombinant adenovirus vector in C57 mice. RESULTS: HBsAg and B7-2 antigens were highly expressed after infecting the 293 and HepG2 cell lines in vitro. The humoral response to hepatitis B surface antigen was mildly induced and could be enhanced by reinjecting a regular dose of HBsAg antigen vaccine. The cell-mediated immune response was highly induced by the recombinant adenovirus infection. No clear side effect was observed after immunization. CONCLUSION: This could be a novel strategy for a development of both preventive and therapeutic vaccines against HBV infection. The recombinant adenovirus vector is an effective and safety vector system suitable to the experiments of gene immunization and gene therapy for incurable diseases.

Adenoviridae↗
PubMed2001

[Influence of electroporation on the biological activities of primary rat hepatocytes].

OBJECTIVE: To investigate the influence of electroporation on the biological activities of primary rat hepatocyte and to optimize the electroporation conditions introducing foreign genes into hepatocytes. METHODS: A single-pulse procedure was performed at low voltage (220-400 V) but high capacitance (500-950 microF). Its influence on hepatocyte activities was detected by Trypan blue exclusion (TBE) and MTT analysis. Besides, ALB, ALT and LDH in the supernatants of hepatocytes were tested by biochemical assay. RESULTS: Little hepatocyte damage and high survival rate (>90%) was found from 36 hours till 9th day of culture. At 36th hour after electroporation, ALB, ALT and LDH in the supernatants of Group B (220V, 950 microF) and C (400 V, 950 microF) were higher than those of control group. Whereas TBE and MTT analysis failed to indicate the significant difference of cell viability between electroporation groups and control group. CONCLUSIONS: This electroporation procedure is one of the optimal choices to introduce foreign genes into primary rat hepatocytes.

Animals↗
PubMed2001

[Characteristics of granular sludge during start-up of the internal circulation].

The quick start-up of the laboratory scale IC reactor and the characteristics of granular sludge during start-up were studied in this paper. The results showed that the first start-up of IC reactor could be finished in 20 days, while secondary start-up only needed 15 days with COD loading rate of 12-15 kg.(m3.d)-1 and COD removal larger than 85%. During start-up, the characteristics of granular sludge changed greatly: average granular diameter was increased from 0.88 mm to 1.25 mm; average settling velocity was enhanced from 35.4 m.h-1 to 105.17 m.h-1; methanogenic activities of the granular increased up to 4 times as large as the seeded sludge; the main methanobacteria was changed from Methanothrix to Methanococcus and Methanobacterium.

Sewage↗
PubMed2001

[Construction of a dicistronic expression plasmid vector containing double-valent hepatitis B surface gene].

OBJECTIVE: In order to enhance vaccine response, we constructed a dicistronic expression plasmid containing double HBsAg immunogenes. METHODS: At first, pcDNA3.1 plasmid vector was digested with NheI and EcoRI to get the coding sequence of the small (S) surface protein of HBV, then cloned into pCI-neo vector and named it pCI-S. By PCR amplification, the product of IRES-S was digested with SalI & BamHI, and cloned into pBluescript IIK+S to generate pBKS-IRES-S vector, then subcloned to the pCI-S plasmid to generate pCI-S-IRES-S, which is a dicistronic plasmid of double value HBsAg genes. RESULTS: Two plasmids we constructed were digested with related restriction nucleic enzymes. Sequence analysis of HBsAg and IRES-S gene did not reveal any mutation. CONCLUSIONS: The construction of dicistronic plasmid of divalue HBsAg immunogenes has been well cloned, which is convenient for further research on cell expression and gene immunization in animals.

Antigens, Viral↗
PubMed2001

[Expression of HBsAg with four eukaryotic expression plasmids in immortalized B-cell line from a chronic hepatitis B patient].

OBJECTIVE: To establish efficient eukaryotic expression system of HBsAg in immortalized B-cell line from a chronic hepatitis B patient, as autologous HLA target cells for detecting HBsAg-specific cytotoxic T-lymphocyte (CTL) response. METHODS: Four eukaryotic expression plasmids inserted HBsAg gene were transfected into immortalized B-cell line from a chronic hepatitis B patient, then cells were selected with G418 or hygromycin B. HBsAg in culture supernatants and cell lysates were detected with enzyme-linked immunosorbent assay (ELISA). RESULTS: All eukaryotic expression vectors-transfected immortalized B-cells produced HBsAg, which was readily detectable in culture supernatants and cell lysates. CONCLUSIONS: Transfection of EBV-immortalized B-cell line with four eukaryotic expression plasmids leads to stable expression of HBsAg, which can be used as autologous HLA target cells for detecting HBsAg-specific CTL response.

Adult↗
PubMed2001

Construction and identification of a single stranded cDNA clone containing full-length genome of hepatitis G virus.

AIM: To construct a single cDNA clone with full-length genome of hepatitis G virus (HGV) could be transcribed and expressed in vitro. METHODS: The 5 initial HGV cDNA fragments of Iw5, Iwq2, Iwh6, Iw3 and Iw3 used in this study were amplified from serum of a Japanese non A-E hepatitis patient. These fragments overlapped and covered the entire genome from 5'-end to 3'-end of HGV cDNA. Overlap extension PCR and ligation methods were used with 12 primers for the construction of a full-length genomic HGV cDNA clone from the subgenomic fragments. RESULTS: A single HGV cDNA clone (pHGVqz) was successfully constructed, physical mapping of the generated pHGVqz found identical to what we expected, and the sequence was deposited with the GenBank under the Accession number AF081782. The analysis of the full-length sequence, which was able to be in vitro transcribed and expressed, showed that this single clone contained 9373 nucleotides (encoding 2873 amino acids), and shared high homologies with other compared HGV isolates. CONCLUSION: A full-length genomic HGV cDNA clone is generated for the first of the kind in this study, it could be expressed and transcripted. This single cDNA clone is expected to be of importance in the investigation on replication and pathogenicity of HGV.

Blotting, Western↗