Biomedical subjects

Yong Luo

Publications and source records attributed to Yong Luo.

31 records · Page 2Linked to original sources

PubMed2005

[The molecular mechanism of PML in inducing apoptosis of bladder cancer cell line].

OBJECTIVE: Study the affection of inducing expression of PML in the apoptosis and the molecular mechanism of bladder cancer. METHODS: PMEP4/PML inducible expression vector was transfected into bladder cancer UM-UC-2 cells by lipofectamine 2000 system. The positive clone cells were selected by 300 microg/ml hygromycin B and confirmed by laser confocal imaging system. Then, using the in vitro DNA ladder apoptotic assay and Western blot, the affection of inducing expression of PML on apoptosis and its molecular mechanism of bladder cancer cell was studied. RESULTS: Comparing with the vector control group, PML specific nuclear speckle significantly increased in the PMEP4/PML bladder cells. DNA ladder assay demonstrated bladder cancer cell expressing PML occurred apoptosis while the control vector cells were not influenced. Overexpression of PML could reduce Survivin expression and upregulate caspase3 and cleaved PARP protein expression CONCLUSION: Our results demonstrated that overexpression of PML could induce bladder cancer cell apoptosis through the caspase dependent pathways.

Apoptosis↗

PubMed2005

Fc- and complement-receptor activation stimulates cell cycle progression of macrophage cells from G1 to S.

Phagocytosis of microorganisms by macrophages is an important host defense mechanism. While studying the phagocytosis of the human pathogenic fungus Cryptococcus neoformans, we noted that macrophage-like J774 cells with ingested fungal cells had frequent mitotic figures. By analyzing the relative proportion of phagocytic cells as a function of cell cycle phase, we observed an increase in S phase cells after Fc-mediated phagocytosis of polystyrene beads, live or heat-killed C. neoformans. This result was confirmed by increased nuclear BrdU incorporation after Fc-mediated phagocytosis. The induced progression to S phase was observed after both Fc- and complement-mediated phagocytosis of live yeasts. Fc-mediated stimulation of cell division did not require ingestion, because it could be triggered by incubating cells in IgG1-coated plates. Phagocytosis-mediated stimulation of replication was confirmed in vitro using primary bone marrow macrophages and in vivo for peritoneal macrophages. We conclude that phagocytosis of microbes or inert particles can stimulate macrophages to enter S phase and commence cell division. This observation suggests a potential mechanism for increasing the number of effector cells after microbial ingestion, but can also promote the spread of infection.

Animals↗

PubMed2005

Solubility of disulfide-bonded proteins in the cytoplasm of Escherichia coli and its "oxidizing" mutant.

AIM: To study the influence of redox environment of Escherichia coli (E. coli) cytoplasm on disulfide bond formation of recombinant proteins. METHODS: Bovine fibroblast growth factor (BbFGF) was selected as a model of simple proteins with a single disulfide bond and free cysteines. Anti-HBsAg single-chain Fv (HBscFv), an artificial multidomain protein, was selected as the model molecule of complex protein with 2 disulfide bonds. A BbFGF-producing plasmid, pJN-BbFGF, and a HBscFv producing-plasmid, pQE-HBscFv, were constructed and transformed into E. coli strains BL21(DE3) and M15(pREP4) respectively. At the same time, both plasmids were transformed into a reductase-deficient host strain, E. coli Origami(DE3). The 4 recombinant E. coli strains were cultured and the target proteins were purified. Solubility and bioactivity of recombinant BbFGF and HBscFv produced in different host strains were analyzed and compared respectively. RESULTS: All recombinant E. coli strains could efficiently produce target proteins. The level of BbFGF in BL21(DE3) was 15-23% of the total protein, and was 5-10% in Origami (DE3). In addition, 65% of the BbFGF produced in BL21(DE3) formed into inclusion body in the cytoplasm, and all the target proteins became soluble in Origami(DE3). The bioactivity of BbFGF purified from Origami(DE3) was higher than its counterpart from BL21(DE3). The ED(50) of BbFGF from Origami(DE3) and BL21(DE3) was 1.6 microg/L and 2.2 microg/L, respectively. Both HBscFv formed into inclusion body in the cytoplasm of M15(pQE-HBscFv) or Origami(pQE-HBscFv). But the supernatant of Origami(pQE-HBscFv) lysate displayed weak bioactivity and its counterpart from M15(pQE-HBscFv) did not display any bioactivity. The soluble HBscFv in Origami(pQE-HBscFv) was purified to be 1-2 mg/L and its affinity constant was determined to be 2.62 x 10(7) mol/L. The yield of native HBscFv refolded from inclusion body in M15(pQE-HBscFv) was 30-35 mg/L and the affinity constant was 1.98 x 10(7) mol/L. There was no significant difference between the bioactivity of HBscFvs refolded from the inclusion bodies produced in different host strains. CONCLUSION: Modification of the redox environment of E. coli cytoplasm can significantly improve the folding of recombinant disulfide-bonded proteins produced in it.

Animals↗

PubMed2005

Multilayer poly(vinyl alcohol)-adsorbed coating on poly(dimethylsiloxane) microfluidic chips for biopolymer separation.

A poly(dimethylsiloxane) (PDMS) microfluidic chip surface was modified by multilayer-adsorbed and heat-immobilized poly(vinyl alcohol) (PVA) after oxygen plasma treatment. The reflection absorption infrared spectrum (RAIRS) showed that 88% hydrolyzed PVA adsorbed more strongly than 100% hydrolyzed one on the oxygen plasma-pretreated PDMS surface, and they all had little adsorption on original PDMS surface. Repeating the coating procedure three times was found to produce the most robust and effective coating. PVA coating converted the original PDMS surface from a hydrophobic one into a hydrophilic surface, and suppressed electroosmotic flow (EOF) in the range of pH 3-11. More than 1,000,000 plates/m and baseline resolution were obtained for separation of fluorescently labeled basic proteins (lysozyme, ribonuclease B). Fluorescently labeled acidic proteins (bovine serum albumin, beta-lactoglobulin) and fragments of dsDNA phiX174 RF/HaeIII were also separated satisfactorily in the three-layer 88% PVA-coated PDMS microchip. Good separation of basic proteins was obtained for about 70 consecutive runs.

DNA↗

PubMed2005

Modification of a poly(methyl methacrylate) injection-molded microchip and its use for high performance analysis of DNA.

Inexpensive and permanently modified poly(methyl methacrylate)(PMMA) microchips were fabricated by an injection-molding process. A novel sealing method for plastic microchips at room temperature was introduced. Run-to-run and chip-to-chip reproducibility was good, with relative standard deviation values between 1-3% for the run-to-run and less than 2.1% for the chip-to-chip comparisons. Acrylonitrile-butadiene-styrene (ABS) was used as an additive in PMMA substrates. The proportions of PMMA and ABS were optimized. ABS may be considered as a modifier, which obviously improved some characteristics of the microchip, such as the hydrophilicity and the electro-osmotic flow (EOF). The detection limit of Rhodamine 6G dye for the modified microchip on the home-made microchip analyzer showed a dramatic 100-fold improvement over that for the unmodified PMMA chip. A detection limit of the order of 10(-20) mole has been achieved for each injected psiX-174/HaeIII DNA fragment with the baseline separation between 271 and 281 bp, and fast separation of 11 DNA restriction fragments within 180 seconds. Analysis of a PCR product from the tobacco ACT gene was performed on the modified microchip as an application example.

DNA↗

PubMed2005

[FK506 promotes apoptosis of macrophages activated by homogenate of allogenic nerve].

OBJECTIVE: To study the effect of FK506 in promoting apoptosis of peripheral blood-derived macrophages activated by homogenate of allogenic nerve tissues. METHODS: Homogenate of the allogenic nerve tissues was prepared using the sciatic nerve and injected in one-month-old SD rats, from which the macrophages activated by the homogenate were collected from the abdominal cavity and cultured in vitro. The cells were divided into 4 groups according to different concentrations of FK506 for treatment, namely 0 (group A, control group), 0.25 ng/ml (group B), 0.5 ng/ml (group C), and 1.0 ng/ml (group D). The cells of the 4 groups were inoculated into 96-well plate respectively for detecting the viability of the macrophages by MTT assay and for morphological evaluation of the cell apoptosis by transmission electron microscopy and fluorescence microscopy. RESULTS: The cells in groups B and C exhibited reduced viability and signs of apoptosis, and necrosis was observed in group D. Transmission electron microscopy and fluorescence microscopy identified early apoptotic changes and the presence of apoptotic body in the macrophages. The apoptotic rates of groups B and C were much higher than that in group A found by flow cytometry. CONCLUSION: FK506 can promote the apoptosis of macrophage activated by allogenic nerve homogenate and reduce macrophage-mediated immunological rejection of peripheral nerve allograft.

Animals↗

PubMed2005

Effects of selenium stress on photosynthetic pigment contents and growth of Chlorella vulgaris.

Changes in photosynthetic pigment and protein contents, growth and the spectral characteristics in Chlorella vulgaris in response to selenium stress were investigated. Carotenoids (beta-carotene and xanthophylls) and chlorophyll (Chl a and Chl b) contents in cells exposed to Se 50 mg/L increased primarily and decreased afterwards, while photosynthetic pigments in cells exposed to Se 800 mg/L decreased significantly. Chlorophyll (Chl) absorption peak at 693 nm and prominent Chl emission peak at 700 nm, weakened significantly after Se stress. The excitation spectra showed a decrease in excitation energy transfer efficiency in Se-stressed cells. Total soluble protein decreased after Se stress. The changes in total Se, Mg(2+), Ca(2+), K(+) and Na(+) concentrations in culture medium and cells were also determined by ICP-AES.

Calcium↗

PubMed2004

Integrated lectin affinity microfluidic chip for glycoform separation.

Lectin affinity chromatography was miniaturized into a microfluidic format, which results in improvement of performance, as compared to the conventional method. A lectin affinity monolith column was prepared in the microchannel of a microfluidic chip. The porous monolith was fabricated by UV-initiated polymerization of ethylene dimethacrylate (EDMA) and glycidyl methacrylate (GMA) in the presence of porogeneities, followed by immobilization of pisum sativum agglutinin (PSA) on the monolith matrix. Using electroosmosis as the driven force, lectin affinity chromatographies of three kinds of glycoprotein, turkey ovalbumin (TO), chicken ovalbumin (CO), and ovomucoid (OM), were carried out on the microfluidic system. All the glycoproteins were successfully separated into several fractions with different affinities toward the immobilized PSA. The integrated system reduces the time required for the lectin affinity chromatography reaction to approximately 3%, thus, the overall analysis time from 4 h to 400 s. Only 300 pg of glycoprotein is required for the whole separation process. Moreover, troublesome operations for lectin affinity chromatography are simplified.

Adsorption↗

PubMed2004

Tumor necrosis factor alpha induction of NF-kappaB requires the novel coactivator SIMPL.

A myriad of stimuli including proinflammatory cytokines, viruses, and chemical and mechanical insults activate a kinase complex composed of IkappaB kinase beta (IKK-beta), IKK-alpha, and IKK-gamma/N, leading to changes in NF-kappaB-dependent gene expression. However, it is not clear how the NF-kappaB response is tailored to specific cellular insults. Signaling molecule that interacts with mouse pelle-like kinase (SIMPL) is a signaling component required for tumor necrosis factor alpha (TNF-alpha)-dependent but not interleukin-1-dependent NF-kappaB activation. Herein we demonstrate that nuclear localization of SIMPL is required for type I TNF receptor-induced NF-kappaB activity. SIMPL interacts with nuclear p65 in a TNF-alpha-dependent manner to promote endogenous NF-kappaB-dependent gene expression. The interaction between SIMPL and p65 enhances p65 transactivation activity. These data support a model in which TNF-alpha activation of NF-kappaB dependent-gene expression requires nuclear relocalization of p65 as well as nuclear relocalization of SIMPL, generating a TNF-alpha-specific induction of gene expression.

Amino Acid Sequence↗

PubMed2003

Electro-acupuncture improves behavior and upregulates GDNF mRNA in MFB transected rats.

Low and high frequency electro-acupuncture (EA) stimulation was used in rats that had been lesioned by medial forebrain bundle transection. Behavioral tests showed that both low and high frequency EA stimulation significantly reduced the amphetamine-induced rotation 2 weeks after the lesion but only high frequency EA improved the rotational behavior at 4 weeks. Analysis of the dopamine content in the striatum did not show any significant change after EA. In situ hybridization showed that high frequency EA stimulation up-regulated the glial cell line-derived neurotrophic factor (GDNF) mRNA in both sides of the globus pallidus, while low frequency EA only affected the unlesioned side. It suggests that the retrograde nourishment of GDNF to the dopaminergic neurons and the balanced activity of different nuclei in the basal ganglia circuit after EA may contribute to the behavioral improvement in these rats, which might be the factors that underlie the effectiveness of EA in the treatment of Parkinson's disease.

Amphetamines↗

PubMed2003

[Apoptosis of keloid-derived fibroblasts induced by Fas gene transfection].

OBJECTIVE: To observe the effect of Fas gene transfection on the apoptosis of keloid-derived fibroblasts. METHODS: The full-length cDNA of Fas was inserted into the multicloning site of the expression vector pcDNA-3.1 by molecular cloning technique, and the recombinant plasmid was transfected into the keloid-derived fibroblasts via lipofectin. Fas monoclonal antibody (mAb) was used to induce the apoptosis of the cells, which was evaluated with HE staining, DNA agarose gel electrophoresis and flow cytometry. RESULTS: The expression plasmid pcDNA-3.1-Fas was constructed successfully. Fas mAb induced apoptosis of these fibroblasts transfected with Fas gene, with the typical features of fibroblast apoptosis observed in the treated cells (e.g. typical apoptotic cell nuclei, DNA ladder and high apoptosis rate as determined by flow cytometer), but not in the control cells. CONCLUSION: Blockage of upstream apoptosis pathway in keloid-derived fibroblasts is due to nonfunction of Fas protein, and mutation of Fas gene may be the pathogenesis of keloids.

Apoptosis↗

PubMed2003

[Expression of a human single-chain Fv antibody against HBsAg in Pichia pastoris].

To express and secrete native HBscFv (anti-HBsAg single-chain Fv) in P. pastoris, HBscFv was amplified from plasmid pGEM-HBscFv, and then sub-cloned into expression vector pPICZalphaA. The resulting plasmid pPIC-HBscFv was linearized and transformed into P. pastoris GS115. The recombinant Pichia strains, identified by direct PCR and Zeocin-resistant screening of Pichia transformants, were cultured and induced with methanol. It was found that recombinant HBscFv, lead by alpha-factor, could be secreted into the culture supernatant to a level of 80mg/L. The bioactivity of Pichia produced HBscFv was confirmed by indirect ELISA, which also suggested that the bioactivity of HBscFv in the culture supernatant reached its peak in 72h and decreased in the late-stage of the induction. PAS staining suggests that HBscFv produced by yeast is poorly glycosylated or none-glycosylated protein.

Blotting, Western↗

PubMed2002

Long-term high-frequency electro-acupuncture stimulation prevents neuronal degeneration and up-regulates BDNF mRNA in the substantia nigra and ventral tegmental area following medial forebrain bundle axotomy.

Electroacupuncture (EA) has been used in China for many years to treat Parkinson's disease (PD) with reportedly effective results. However, the physiological and biological mechanism behind its effectiveness is still unknown. In the present study, different frequencies of chronic EA stimulation (0, 2, 100 Hz) were tested in a partially lesioned rat model of PD which was induced by transection of the medial forebrain bundle (MFB). After 24 sessions of EA stimulation (28 days after MFB transection), dopaminergic neurons in the ventral midbrain were examined by immunohistochemical staining, and brain-derived neurotrophic factor (BDNF) mRNA levels in ventral midbrain were measured by in situ hybridization. The results show a marked decrease of dopaminergic neurons on the lesioned side of the substantia nigra (SN) comparing with the unlesioned side. Zero Hz and 2 Hz EA stimulation had no effect on the disappearance of dopaminergic neurons. However, after 100 Hz EA, about 60% of the tyrosine hydroxylase (TH)-positive neurons remained on the lesioned side of the SN. In addition, levels of BDNF mRNA in the SN and ventral tegmental area (VTA) of the lesioned side were significantly increased in the 100 Hz EA group, but unchanged in the 0 and 2 Hz groups. Our results suggest that long-term high-frequency EA is effective in halting the degeneration of dopaminergic neurons in the SN and up-regulating the levels of BDNF mRNA in the subfields of the ventral midbrain. Activation of endogenous neurotrophins by EA may be involved in the regeneration of the injured dopaminergic neurons, which may underlie the effectiveness of EA in the treatment of PD.

Animals↗