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Biomedical subjects

Feng Gao

Publications and source records attributed to Feng Gao.

At least 217 records · Page 12Linked to original sources
PubMed2004

Brain hyaluronan binding protein inhibits tumor growth.

BACKGROUND: Great efforts have been made to search for the angiogenic inhibitors in avascular tissues. Several proteins isolated from cartilage have been proved to have anti-angiogenic or anti-tumour effects. Because cartilage contains a great amount of hyaluronic acid (HA) oligosaccharides and abundant HA binding proteins (HABP), therefore, we speculated that HABP might be one of the factors regulating vascularization in cartilage or anti-angiogenesis in tumours. The purpose of this research was to evaluate the effects of hyaluronan binding protein on inhibiting tumour growth both in vivo and vitro. METHODS: A unique protein termed human brain hyaluronan (HA) binding protein (b-HABP) was cloned from human brain cDNA library. MDA-435 human breast cancer cell line was chosen as a transfectant. The in vitro underlying mechanisms were investigated by determining the possibilities of MDA-435/b-HABP colony formation on soft agar, the effects of the transfectant on the proliferation of endothelial cells and the expression levels of caspase 3 and FasL from MDA-435/b-HABP. The in vivo study included tumour growth on the chorioallantoic membrane (CAM) of chicken embryos and nude mice. RESULTS: Colony formation assay revealed that the colonies formed by MDA-435/b-HABP were greatly reduced compared to mock transfectants. The conditioned media from MDA-435/b-HABP inhibited the growth of endothelial cells in culture. Caspase 3 and FasL expressions were induced by MDA-435/b-HABP. The size of tumours of MDA-435/b-HABP in both CAM and nude mice was much smaller than that of MDA-435 alone. CONCLUSIONS: Human brain hyaluronan binding protein (b-HABP) may represent a new kind of naturally existing anti-tumour substance. This brain-derived glycoprotein may block tumour growth by inducing apoptosis of cancer cells or by decreasing angiogenesis in tumour tissue via inhibiting proliferation of endothelial cells.

Animals↗
PubMed2004

[Re-growth of induced-osseous tissue encapsulated in muscular fasciae for prefabrication of an osteo-musculo-cutaneous flap].

OBJECTIVE: To improve the survival of mesenchymal stem cells (MSCs) for prefabrication of an osteo-musculo-cutaneous flap. METHODS: In a mouse model, the compound of MSCs and p(3HB-co-3HH) were embeded in the latissimus dorsi muscle as an experimental group and the muscle pocket of the buttock as the control. The examinations of the HE staining, hybridization in situ of osteonectin mRNA and Von kossa staining were used to evaluate the results. RESULTS: The expression of osteonectin mRNA and the Von kossa staining showed that the latissimus dorsi muscle group was superior to the control in 2 weeks and 4 weeks after the surgery in vivo. CONCLUSION: The results indicate that the above-mentioned technique may be a good alternative for the prefabrication of the osteo-musculo-cutaneous flap.

Animals↗
PubMed2004

[Transplantation of adrenocortical cells in allorat using porous PHB as cell carrier].

This experiment was designed to investigate the feasibility of transplanatation of using porous PHB as cell carrier for the transplanatation of adrenocortical cells. Adrenocortical cells from rat adrenal gland were separated and cultured in vitro. The effect of PHB on the proliferation and secretory function of adrenocortical cells were evaluated by MTT and RIA methods. Then adrenocortical cells were seeded into porous PHB. After the cells were cultured in vitro for about seven days, they were implanted into the rats having undergone bilateral adrenalectomy. The changes of blood corticosterone and aldosterone and the local histological changes in these rats were observed. Adrenocortical cells were able to grow and survive on PHB. No effect on the proliferation and secretory function of adrenocortical cells were observed. Most bilateral adrenalectomized rats bearing the transplanted adrenocortical cells within PHB (study group) survived longer than did the adrenalectomized rats in control group. The blood corticosterone level and aldosterone level of study group were higher than those of control group. It was found that PHB has no effects on the survival, proliferation and secretory function of adrenocortical cells. Adrenocortical cells within PHB can survive a period of time and can secrete corticosterone and aldosterone which can meet the needs of the adrenalectomized rats. PHB can degrade slowly in vivo. It is feasible to perform transplantation of adrenocortical cells using porous PHB as cell carrier.

Adrenal Cortex↗
PubMed2004

[Effect of S-2-(3-aminopropylamino) ethyl phosphorothioic acid on apoptosis and proliferation inhibition of HL-60 cell line].

To study the effects of S-2-(3-aminopropylamino) ethyl phosphorothioic acid (WR-2721, amifostine) on proliferation inhibition and apoptosis of HL-60 human leukemia cell line, the cell apoptosis rate of HL-60 was determined by annexin V/PI double staining method. Cell proliferation and chemotherapy sensitivity were analyzed with XTT assay, and the changes of cell cycle were observed through flow cytometry. The results showed that WR-2721 could significantly inhibit HL-60 cell proliferation. After treatment (30 min, 37 degrees C) with WR-2721, the sensitivity of HL-60 cells to VP16 was enhanced, and the IC(50) descended from 52.5 micro g/ml to 40.5 microg/ml. After 72 hours treatment of HL-60 cells with WR-2721, the early apoptotic cells (annexin V-FITC positive/PI negative) were increased from (5.5 +/- 1.9)% to (48.5 +/- 8.4)% (P < 0.001), late apoptotic cells (annexin V-FITC positive/PI positive) were increased from (1.2 +/- 0.5)% to (39.0 +/- 4.0)% (P < 0.001), and HL-60 cells were arrested in G(2)-M phase. In conclusion, WR-2721 treatment can enhance HL-60 cell chemotherapy sensitivity to VP16, inhibit proliferation, induce apoptosis and accumulation of cells in G(2)-M phase.

Amifostine↗
PubMed2004

[Optimization of piggery wastewater treatment with combined anaerobic hydrolysis and SBR process].

Anaerobic sequence batch reactor and aerobic sequence batch reactor were combined to treat the piggery wastewater. The ASBR was used to digest the wastewater for primary organic matter removal. Infections of digestion time to the wastewater's BOD/COD and to the nitrogen removal in behind SBR were studied. The result indicated that the wastewater with 36 hours' digestion retained high BOD/COD ratio of about 0.4. The nitrogen removal efficiency of this kind of wastewater in behind SBR was high with the effluent NH4+-N concentration less than 10 mg/L and a removal ratio higher than 99%. The total BOD5 removal ratio of A/O SBR was higher than 98% but the effluent COD(Cr) concentration couldn't meet the discharging standard before coagulating sedimentation.

Aerobiosis↗
PubMed2004

[Study on the Eu-containing coordination polymer. I. Structural characterization of Eu (III)-thienyltrifluroacetone-poly (styrene-acrylic acid)].

Three samples (a), (b) and (c) of luminescent Eu-containing copolymer (NaEu(III)-TTA-PSAA) were synthesized through the reaction of copolymer of acrylic acid and styrene (Mw = 3000) with metalorganic complex (NaEu(TTA)4) obtained from Eu and thienyltrifluroacetone. These samples of coordination polymers were characterized by FTIR, UV and XPS, and their composition and structures were determined. The results of electrical conductivity methods and elemental analysis indicated that there were different compositions and structures of these coordination polymers in different pH. The results of elemental analysis also showed that the content of Eu3+ in sample (a), (b) and (c) was 11.89%, 12.55% and 13.41%, respectively.

Acrylamides↗
PubMed2004

[Studies on application and mechanism of energy transfer system of acridine orange (AO)-rhodamine B (RB) dimer in the determination of DNA].

Not only dye monomer is the form of energy transfer but also dye dimer is the effective form of energy transfer. In this work, the energy transfer system of acridine orange (AO)-rhodamine B (RB) dimer was built for the determination of DNA as fluorescence probe. At the same time, the mechanism was also considered. Under the optimum experimental conditions, the linear range of this assay was 0.33-1.33 mg x L(-1) for fish sperm DNA and 0.33-3.33 mg x L(-1) for calf thymus DNA, the detection limit was 1.63 x 10(-3) mg x L(-1) for fish sperm DNA and 1.52 x 10(-3) mg x L(-1) for calf thymus DNA, respectively. The RSD for the determination of 1.00 mg x L(-1) DNA was 2.40% for fsDNA and 2.00% for ctDNA, respectively. The method was used for the determination of DNA in synthetic samples with satisfied results.

Acridine Orange↗
PubMed2003

Prediction of proteinase cleavage sites in polyproteins of coronaviruses and its applications in analyzing SARS-CoV genomes.

Recently, we have developed a coronavirus-specific gene-finding system, ZCURVE_CoV 1.0. In this paper, the system is further improved by taking the prediction of cleavage sites of viral proteinases in polyproteins into account. The cleavage sites of the 3C-like proteinase and papain-like proteinase are highly conserved. Based on the method of traditional positional weight matrix trained by the peptides around cleavage sites, the present method also sufficiently considers the length conservation of non-structural proteins cleaved by the 3C-like proteinase and papain-like proteinase to reduce the false positive prediction rate. The improved system, ZCURVE_CoV 2.0, has been run for each of the 24 completely sequenced coronavirus genomes in GenBank. Consequently, all the non-structural proteins in the 24 genomes are accurately predicted. Compared with known annotations, the performance of the present method is satisfactory. The software ZCURVE_CoV 2.0 is freely available at http://tubic.tju.edu.cn/sars/.

Amino Acid Sequence↗
PubMed2003

A peptide with three hyaluronan binding motifs inhibits tumor growth and induces apoptosis.

A number of hyaluronan (HA) binding proteins such as soluble CD44, receptor for hyaluronan-mediated motility (RHAMM), and metastatin inhibit tumor growth and metastasis. To determine whether the HA binding motif is the element responsible for the antitumor effect of this family of proteins, we examined the biological activity of a 42-amino acid peptide (designated as BH-P) that contains three HA binding motifs [B(X(7))B] from human brain HA binding protein. In initial experiments with cultured cells, we found that synthetic BH-P inhibited the proliferation and colony formation of tumor cells. It also blocked the growth of tumors on the chorioallantoic membranes of 10-day chicken embryos. In addition, MDA-435 melanoma cells that had been transfected with an expression vector for BH-P grew at a slower rate in nude mice than the vector-alone transfectants. Final studies revealed that the BH-P could activate caspase-8, caspase-3, and poly(ADP-ribose) polymerase and trigger the apoptosis of tumor cells. Taken together, these results suggest that the HA binding motif that is present in HA binding proteins may be responsible for the antitumor effect exerted by the members of this family.

Amino Acid Motifs↗
PubMed2003

Residues 45 and 404 in the murine reduced folate carrier may interact to alter carrier binding and mobility.

The reduced folate carrier (RFC), a facilitative transporter, plays a major role in the delivery of reduced folates and antifolates into cells. Previous studies indicated that mutations of E45K in the first transmembrane domain (TMD), and K404L in the 11th TMD, produce selective and opposite alterations in binding of natural folate substrates to murine RFC. The former mutation is frequently associated with antifolate resistance. The current study was designed to determine whether there might be an interaction between these sites by comparing the transport properties of RFC-null cell lines stably transfected with K404E, E45K, or E45K/K404E carriers. These studies demonstrated that: (1) All mutant carriers were inserted into the plasma membrane. (2) In the K404E mutant, the influx K(t)'s for 5-formyltetrahydrofolate and 5-methyltetrahydrofolate were markedly increased, and to a much smaller extent folic acid, as compared to L1210 cells. However, with introduction of a second E45K mutation the influx K(t) for these folates reverted to those of the E45K cells which retained wild-type binding for 5-methyltetrahydrofolate and enhanced binding of 5-formyltetrahydrofolate and folic acid. (3) The influx V(max) of the E45K mutant was markedly reduced. Introduction of the second K404E mutation doubled this parameter and the ratio of V(max) to K(t) for 5-formytetrahydrofolate was restored to approximately 50% that of the wild-type carrier consistent with a substantial increase in function. (4) Chloride inhibits wild-type RFC but the E45K mutant requires chloride for activity. The K404E mutant is also suppressed by chloride but introduction of the K404E mutation decreased the chloride-dependence of E45K. The results suggest that there is an interaction between the E45 and K404 residues in the first and 11th TMDs, respectively, but that the E45 residue appears to be the more dominant determinant of binding and anion sensitivity.

Amino Acid Substitution↗
PubMed2003

Crystallization and preliminary X-ray diffraction analysis of post-fusion six-helix bundle core structure from Newcastle disease virus F protein.

Fusion of virus members from the Paramyxoviridae family involves two glycoproteins. They are termed attachment glycoprotein (HN, H or G) and fusion protein (F). The F protein contains two highly conserved heptad-repeat (HR) regions, HR1 and HR2. Through conformational changes in the F protein, HR1 and HR2 are believed to form a stable six-helix coiled-coil bundle during the membrane-fusion process. However, no crystal structure has yet been documented for this state in the Newcastle disease virus (NDV, a member of the Paramyxoviridae family) F protein, despite the recent success on its F(0) crystal structure (Chen et al., 2001), which was thought to represent the pre-fusion conformation of F glycoprotein. In this study, a single-chain polypeptide constructed by linking two truncated HR regions of the NDV F protein has been expressed, purified and crystallized by means of the hanging- or sitting-drop vapour-diffusion method. Crystals in hexagonal and trapezoid forms with a resolution limit of 2.6 A were obtained. These crystals belonged to space group C2, with unit-cell parameters a = 66.4, b = 38.2, c = 102.0 A, beta = 100.2 degrees. Crystals in the rhombic form with a resolution limit of 2.5 A were also obtained. These crystals belonged to space group P2(1), with unit-cell parameters a = 59.0, b = 31.9, c = 62.3 A, beta = 117.0 degrees. This will add to the repertoire of viral fusion protein post-fusion state structures and help further the understanding of the molecular mechanism of enveloped virus fusion.

Crystallization↗
PubMed2003

Human anti-beta-amyloid antibodies block beta-amyloid fibril formation and prevent beta-amyloid-induced neurotoxicity.

The accumulation of beta-amyloid (A beta) in neuritic plaques is thought to be causative for the progression of Alzheimer's disease (AD). Recently, both active immunization and passive administration of A beta antibodies dramatically attenuated amyloid plaque deposition, neuritic dystrophy, astrogliosis and behaviour deficits in transgenic animals. In addition, we and others have found that titres of naturally occurring anti-A beta antibodies in the CSF of AD patients are significantly lower than those in age-matched controls. Treatment with intravenous immunoglobulins (a preparation that contained anti-A beta antibodies) significantly lowered CSF levels of A beta in non-demented patients. In this study, anti-A beta antibodies were isolated from immunoglobulin preparations and these anti-A beta antibodies strongly block fibril formation or disrupt formation of fibrilar structures. Furthermore, these antibodies almost completely prevented neurotoxicity of A beta. In contrast, immunoglobulins depleted of anti-A beta antibodies had little effect on A beta fibril formation or protection of neuronal cells. This study supports the findings that human anti-A beta antibodies may interfere with the pathogenesis of AD by more than one mechanism, and administration of polyclonal human anti-A beta antibodies isolated from plasma is a potential therapeutic agent to prevent or slow down disease progression.

Amyloid beta-Peptides↗
PubMed2003

Non-steroidal anti-inflammatory drugs affect the methotrexate transport in IEC-6 cells.

Methotrexate (MTX) is used not only for the cancer chemotherapy but also for the treatment of rheumatic disease, often together with non-steroidal anti-inflammatory drugs (NSAIDs). MTX is actively cotransported with H(+) in the small intestine, mediated by a reduced folate carrier (RFC). The coadministration of some NSAIDs with MTX to rats caused a decrease of MTX absorption through the small intestine. This may be due to the uncoupling effect of oxidative phosphorylation of the NSAIDs. The present study investigated whether flufenamic acid, diclofenac and indomethacin, NSAIDs, decreased ATP content of rat-derived intestinal epithelial cell line IEC-6 cells and affected the MTX transport in IEC-6 cells. The MTX uptake in IEC-6 cells was dependent on medium pH and maximum around pH 4.5-5.5. The MTX uptake was composed of a transport inhibited by 4, 4'-diisothiocyanostilbene-2, 2'-disulfonic acid (DIDS) and a non-saturable one. The DIDS-sensitive component in the MTX uptake showed a saturation kinetics (Michaelis-Menten constant (Km): 3.91 +/- 0.52 microM, Maximum velocity (Vmax): 94.66 +/- 6.56 pmol/mg protein/5 min). The cellular ATP content in IEC-6 cells decreased significantly at 30 min after the cells were started to incubate with the NSAIDs (250 microM flufenamic acid, 500 microM diclofenac and 500 microM indomethacin). The MTX uptake in IEC-6 cells in the presence of the NSAIDs decreased with the reduction of cellular ATP content and showed a good correlation with the ATP content (correlation coefficient: 0.982). Thus it seems likely that the ATP content in IEC-6 cells with the NSAIDs decreased due to the uncoupling effect of oxidative phosphorylation of the NSAIDs, resulting in the inhibition of the secondary active transport of MTX in IEC-6 cells. The present results also suggest that IEC-6 cells are useful to evaluate the drug interaction relating to this carrier system.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2003

Interleukin-13 gene transfer protects rat livers from antigen-independent injury induced by ischemia and reperfusion.

BACKGROUND: Ischemia-reperfusion (I/R) injury is a prime inflammatory factor in the dysfunction of orthotopic liver transplants. Interleukin (IL)-13 suppresses macrophage production of proinflammatory mediators. This study explores the effects of adenovirus (Ad)-based IL-13 gene transfer in rat models of hepatic I/R injury. METHODS: The authors used a model of warm in situ ischemia followed by reperfusion, and ex vivo cold ischemia followed by transplantation. RESULTS: In a model of warm in situ ischemia followed by reperfusion, Ad-based IL-13 significantly diminished hepatocellular injury, assessed by serum glutamic oxaloacetic transaminase (SGOT) levels, as compared with Ad-based beta-galactosidase (gal)-treated livers. In a model of ex vivo cold ischemia followed by transplantation, the survival of liver grafts increased from 50% in Ad-beta-gal untreated controls to 100% after Ad-IL-13 gene therapy. This beneficial effect correlated with improved liver function (SGOT levels), preservation of hepatic histologic integrity and architecture (Suzuki criteria), and depression of neutrophil infiltration (myeloperoxidase assay). Ad-IL-13 diminished activation of macrophage-neutrophil-associated tumor necrosis factor-alpha, macrophage inflammatory protein-2, and endothelial-dependent E-selectin, but increased type 2 IL-4 and IL-13 expression. CONCLUSIONS: This study documents striking cytoprotective effects of virally induced IL-13 against hepatic I/R injury in two clinically relevant rat models of hepatic I/R injury. These data provide the rationale for novel therapeutic approaches to maximize the organ donor pool through the safer use of liver transplants despite prolonged periods of warm or cold ischemia, or both.

Adenoviridae↗
PubMed2003

[Cloning and biological activities of riboenzymes against major histocompatibility complex class II transactivator].

OBJECTIVE: To investigate the cloning and biological activities of riboenzymes against major histocompatibility complex (MHC) class II transactivator (CIITA) so as to explore the feasibility of using hammerhead riboenzyme to create immune tolerance. METHODS: Three riboenzymes against MHC CIITA were synthesized and their activities were evaluated in vitro. Rz464, the riboenzyme with a better digestion effect, was inserted into the vector pIRES2-EGFP (then called pRz464). Human B lymphoma cells of Daudi line were cultured and transfected with pRz464 (then called pRz464-D). Cultured Daudi cells transfected with riboenzyme without the ability against CIITA (Rz-D) were used as control group. The expressions of classic MHC CIITA (HLA-DR, DP, and DQ) on the surface of Daudi cells before and after transfection were examined by flow cytometry. RESULTS: The expressions of HLA-DR, DP, and DQ on the surface of cultured Daudi cells (Rz-D) were 97.9 +/- 0.8%, 94.3 +/- 1.1%, and 54.4 +/- 3.1% respectively. The expressions of HLA-DR, DP, and DQ were inhibited by 88.4%, 83.5%, and 93.4% respectively on the surface of pRz464-D cells. CONCLUSION: The hammerhead riboenzyme Rz464 inhibits the expression of CIITA mRNAs, thus inhibiting the expression of MHC II molecules. It may be used in antigen-specific tolerance induction in allo-transplantation.

Cloning, Molecular↗