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Xin-Gang Li

Publications and source records attributed to Xin-Gang Li.

10 recordsLinked to original sources
PubMed2006

Laboratory column study for remediation of MTBE-contaminated groundwater using a biological two-layer permeable barrier.

In this study, an in situ biological two-layer permeable reactive barrier system consisting of an oxygen-releasing material layer followed by a biodegradation layer was designed to evaluate the remediation effectiveness of MTBE-contaminated groundwater. The first layer containing calcium peroxide (CaO(2)) and other inorganic salts is to provide oxygen and nutrients for the immobilized microbes in the second layer in order to keep them in aerobic condition and maintain their normal metabolism. Furthermore, inorganic salts such as potassium dihydrogen phosphate (KH(2)PO(4)) and ammonium sulphate ((NH(4))(2)SO(4)) can also decrease the high pH caused by the alkali salt degraded from CaO(2). The second layer using granular expanded perlite as microbial carrier is able to biodegrade MTBE entering the barrier system. Batch experiments were conducted to identify the appropriate components of oxygen-releasing materials and the optimum pH value for the biodegradation of MTBE. At pH=8.0, the biodegradation efficiency of MTBE is the maximum and approximately 48.9%. A laboratory-scale experiment using two continuous upflow stainless-steel columns was then performed to evaluate the feasibility of this designed system. The fist column was filled with oxygen-releasing materials at certain ratio by weight. The second column was filled with expanded perlite granules immobilizing MTBE-degrading microbial consortium. Simulated MTBE-contaminated groundwater, in which dissolved oxygen (DO) content was 0mg/L, was pumped into this system at a flow rate of 500mL/d. Samples from the second column were analyzed for MTBE and its major degradation byproduct. Results showed that MTBE could be removed, and its metabolic intermediate, tert-butyl alcohol (TBA), could also be further degraded in this passive system.

Bacteria, Aerobic↗
PubMed2006

Removal of ammonium from wastewater using calcium form clinoptilolite.

The paper concerns the removal of ammonium ions from aqueous solution using a modified clinoptilolite-Ca(2+)-formed clinoptilolite (CaY) prepared from natural clinoptilolite. The batch study results show that the pH has an effect on ammonium adsorption capacity as it can influence both the character of the exchanging ions and the clinoptilolite itself; the CaY has a high selectivity to NH(4)(+) and the exchange decreases with increasing temperature; ammonium ion uptake onto CaY was suitably described by the Langmuir model. The column results indicated that the effluent of simulated wastewater treated with CaY could meet the integrated wastewater discharge standard of China, and CaY can be circulated through regenerating by Ca(OH)(2).

Adsorption↗
PubMed2006

[Effect of curcumin on acetylation of histone H3 in human lymphoma cell line Raji].

BACKGROUND & OBJECTIVE: Epigenetic change is an important mechanism of oncogenesis. The inhibitors of methyltransferases and deacetylases, with epigenetic modificative effects, could inhibit proliferation and induce apoptosis of tumor cells. This study was to investigate the effects of curcumin on the acetylation of histone H3 and the expression of p21(WAF1/CIP1) gene in human lymphoma cell line Raji. METHODS: Raji cells were treated with 25 micromol/L curcumin. The levels of acetylated histone H3 and p21WAF1/CIP1 were detected by Western blot, the expression of p21(WAF1/CIP1) gene was detected by reverse transcription-polymerase chain reaction (RT-PCR), and the level of acetylated histone H3 at the site of p21(WAF1/CIP1) promoter gene was examined by chromatin immunoprecipitation assay. Cell cycle distribution was studied by flow cytometry. RESULTS: Curcumin induced hyperacetylation of histone H3 at the site of p21(WAF1/CIP1) promoter by 1.9 folds, and enhanced the levels of p21(WAF1/CIP1) mRNA by 4.2 folds and protein by 5.1 folds 24 h after treatment. Raji cells were arrested at G(2)/M phase when treated with curcumin for 24 h, and at G(0)/G(1) phase when treated for 36 h. CONCLUSION: Curcumin, with epigenetic modificative effects, could enhance the acetylayion of histone H3 at the site of p21(WAF1/CIP1) promoter gene, improve transcription of p21(WAF1/CIP1) gene, and arrest cell cycle progression of Raji cells.

Acetylation↗
PubMed2006

[Epigenetic modification in human leukemia].

Epigenetic modification, which involve DNA methylation, RNA-associated silencing and histone modification, is implicated in cell proliferation, differentiation, survival, apoptosis and malignant transformation. Some leukemogenesis has been shown to be aberrance of epigenetic modification. This paper discussed the potential causes of some of leukemias correlating with the methylation of cell cycle regulation genes, small interference RNA and modification abnormality of histone after translation. The study on epigenetic modification abnormality of leukemia cells provides a new strategy for treatment of leukemia.

DNA Methylation↗
PubMed2005

[Regulation of AAV-mediated glial cell-line derived neurotrophic factor expression by using improved Tet-on trans-activator].

OBJECTIVE: To control the expression of AAV-mediated glial cell-line derived neurotrophic factor (GDNF) gene purposely by incorporating novel Tet-On trans-activator rtTA2s-S2, which prevents potential harms caused by over-expression of recombinant target genes. METHODS: Oligonucleotide with specific monocloning sites was inserted into the hHG part of pAAV-GDNFflag. Trans-activator from pUHrT61-rtTA2s-S2 and TRE from pTRE-d2EGFP were amplified by PCR and inserted into pCRII-TOPO respectively. Possible mutation was eliminated by sequencing. TRE and rtTA2s-S2 were then inserted into the oligonucleotide of pAAV-GDNFflag to form pAAV-rtTA2s-S2-TRE-GDNFflag. pAAV-rtTA2s-S2-TRE-d2EGFP was constructed by replacing the GDNFflag part with d2EGFP. The plasmids were digested by Xba I and compared with theoretic values. HEK 293 cells were cultured and co-transfected with pAAV-GDNFflag and helper plasmids pHLP19 and pAdeno5 so as to complete the package of recombinant adeno-associated virus (rAAV) Crude virus lysate was purified by two-sequential continuous CsCl gradient ultracentrifugation, dialyzed and condensed by millipore filter. The titer of rAAV was determined by real-time quantitative PCR. Another HEK293 cells were cultured, transfected with rAVV, and then cultured in 2 kinds of culture fluid: with or without doxycyclin (Dox). Fluorescence microscopy was used to calculate the percentage of fluorescent cells so as to detect AAV-rtTA2s-S2-TRE-d2EGFP, and Western blotting was used to detect the GDNF protein in the lysate of the HEK293 cells, thus testifying the regulatory function in vitro of rtTA2s-S2. Twenty male Wistar mice were randomly divided into 2 groups: experiment group, fed with Dox and sucrose (Dox-positive group), and control group, fed with only sucrose (Dox-negative group). Two days after AAV-rtTA2s-S2-TRE-GDNF was injected into the gastrocnemius muscles of the mice. Two weeks the mice were killed and their gastrocnemius muscles were taken out. ELISA was used to examine the content of GDNF in the homogenate of gastrocnemius muscle so as to examine the regulatory effect of rtTA2s-S2 in vivo. RESULTS: Tests showed that the recombinant plasmids were constructed correctly. The fluorescent cell positive rate in the Dox-positive culture fluid of HEK293 cells was 52.4%, significantly higher than that in the Dox-negate culture fluid (7.2%, P < 0.01). Western blotting of the HEK 293 cell lysate showed clear band of GDNF in the Dox-positive group and failed to show visible band in the Dox-negative group. The content of GDNF in the homogenate of gastrocnemius muscles of the Dox-positive group was 32.6pg/ml +/- 2.6 pg/ml, significantly higher than that of the Dox-negative group (10.1 pg/ml +/- 2.4 pg/ml, P < 0.01). CONCLUSION: Novel Tet-on trans-activator rtTA2s-S2 regulates downstream AAV-mediated GDNF expression in a stringent manner and does not impair AAV infecting efficiency when constructed together with TRE and GDNF within one AAV vector.

Dependovirus↗
PubMed2005

Groundwater remediation engineering sparging using acetylene--study on the flow distribution of air.

Air sparging (AS) is an emerging method to remove VOCs from saturated soils and groundwater. Air sparging performance highly depends on the air distribution resulting in the aquifer. In order to study gas flow characterization, a two-dimensional experimental chamber was designed and installed. In addition, the method by using acetylene as the tracer to directly image the gas distribution results of AS process has been put forward. Experiments were performed with different injected gas flow rates. The gas flow patterns were found to depend significantly on the injected gas flow rate, and the characterization of gas flow distributions in porous media was very different from the acetylene tracing study. Lower and higher gas flow rates generally yield more irregular in shape and less effective gas distributions.

Acetylene↗
PubMed2004

Strain improvement and metabolic flux analysis in the wild-type and a mutant Lactobacillus lactis strain for L(+)-lactic acid production.

The effects of initial glucose concentration and calcium lactate concentration on the lactic acid production by the parent strain, Lactobacillus lactis BME5-18, were studied. The results of the experiments indicated that glucose and lactate repressed the cell growth and the lactic acid production by Lactobacillus lactis BME5-18. A L(+)-lactic acid overproducing strain, Lactobacillus lactis BME5-18M, was screened by mutagenizing the parent strain with ultraviolet (UV) light irradiation and selecting the high glucose and lactate calcium concentration repression resistant mutant. Starting with a concentration of 100g L(-1) glucose, the mutant produced 98.6 g L(-1) lactic acid after 60 h in flasks, 73.9% higher than that of the parent strain. The L(+)-lactic acid purity was 98.1% by weight based on the amount of total lactic acid. The culture of the parent strain could not be analyzed well by conventional metabolic flux analysis techniques, since some pyruvate were accumulated intracellularly. Therefore, a revised flux analysis method was proposed by introducing intracellular pyruvate pool. Further studies demonstrate that there is a high level of NADH oxidase activity (12.11 mmol mg(-1) min(-1)) in the parent strain. The molecular mechanisms of the strain improvement were proposed, i.e., the high level of NADH oxidase activity was eliminated and the uptake rate of glucose was increased from 82.1 C-mmol (g DW h)(-1) to 98.9 C-mmol (g DW h)(-1) by mutagenizing the parent strain with UV, and therefore the mutant strain converts mostly pyruvate to lactic acid with a higher productivity (1.76 g L(-1) h(-1)) than the parent strain (0.95 g L(-1) h(-1)).

Computer Simulation↗
PubMed2004

[Effect of curcumin on STAT5 signaling pathway in primary CML cells].

To study the effect of curcumin on signaling pathway of signal transducers and activators of transcription (STAT5) in primary newly-diagnosed chronic myelocytic leukemia (CML) cells, and to explore the clinical significance of curcumin in the treatment of primary CML cells, the cells were randomly divided into 3 groups: normal control group, CML cells group, and curcumin group; the cellular proliferation was assayed by MTT test; the expression of cellular STAT5 mRNA in CML cells was detected by RT-PCR; the activation of STAT5 in CML cell was detected by electrophoretic mobility shift assay (EMSA). The results showed that the cellular proliferation of curcumin group (OD value 0.640 +/- 0.073) was decreased, as compared with that of the CML cells group (OD value 0.856 +/- 0.083, P <0.01). The expression levels of STAT5 mRNA in CML cells group (integral ratio of OD 1.782 +/- 0.156) were significantly greater than that in the normal control group (integral ratio of OD 0.289 +/- 0.025, P <0.01). The expression of STAT5 mRNA in curcumin group (integral ratio of OD 1.398 +/- 0.126) was significantly decreased as compared with that in the CML cells group (P <0.01). The activation of STAT5 was significantly increased in CML cells group (gray value 5323.375 +/- 515.640) as compared with that in the normal control group (gray value 2943.000 +/- 273.377, P <0.01). The activation of STAT5 of curcumin group (gray value 4331.750 +/- 398.035) was significantly decreased as compared with that of CML cells group (P <0.01). It is concluded that the cellular proliferation and the expression of STAT5 mRNA are increased in the primary CML cells. The activation of STAT5 in primary CML cells is markedly enhanced. STAT5 signaling pathway may be involved in the proliferation of primary CML cells. Curcumin can inhibit the cellular proliferation and the expression of STAT5 mRNA, and down-regulate the activation of STAT5 in primary CML cells. Curcumin may be used in treatment of leukemia.

Adult↗
PubMed2003

Fed-batch fermentation of Lactobacillus lactis for hyper-production of L-lactic acid.

A fed-batch fermentation of Lactobacillus lactis to produce L-lactic acid was developed in which the residual glucose concentration in the culture was used to control a continuous feeding strategy. Up to 210 g L-lactic acid l(-1) (97% yield) was obtained. The maximal dry cell was 2.7 g l(-1) and the average L-lactic acid productivity was 2 g l(-1) h(-1).

Bioreactors↗