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Jian Chen

Publications and source records attributed to Jian Chen.

At least 55 records · Page 3Linked to original sources
PubMed2006

Expression, purification and characterization of human GM-CSF using silkworm pupae (Bombyx mori) as a bioreactor.

To date, many recombinant proteins have been expressed in Bombyx mori cells or silkworm larvae, apart from in pupae. Silkworm pupae may be more suitable for the expression of heterologous proteins as a bioreactor. If maintained at an appropriate temperature, silkworm pupae could be inoculated with recombinant baculovirus for the expression of a protein of interest. In this study, human granulocyte-macrophage colony-stimulating factor was successfully expressed in silkworm pupae using B. mori nucleopolyhedrovirus, purified and characterized with respect to its physico-chemical properties. The target protein expressed had an apparent molecular mass of 29 kDa and an isoelectric point of 5.1. The protein was purified using three chromatographic steps with a final recovery of 10.3%. Finally, approximately 3.5mg of the protein was obtained with a biological activity of up to 8.4 x 10(6) cfu mg(-1). The results of this study suggest that silkworm pupae represent a convenient and low-cost bioreactor for the expression of heterologous proteins.

Animals↗
PubMed2006

Effect and mechanism of epidermal growth factor on proliferation of GL15 gliomas cell line.

The effects of epidermal growth factor (EGF) on proliferation of G15 glioma cells and the possible mechanisms were investigated. GFAP and EGFR expression was detected by immunohistochemical method. After the cells were treated with EGF at different concentrations, cell count method was used to determine the proliferation of glioma cells, cell cycle and apoptosis were analyzed by flow cytometry (FCM), and laser scan confocal microscope (LSCM) was used to measure the cytoplasmic free calcium. The results showed that GFAP was diffusedly expressed in GL15 cells and EGFR was over-expressed. EGF at doses of < or =1 ng/mL could significantly stimulate cell proliferation, cells in phase G0/G1 decreased, and those in phase S increased. EGF at doses of 10 and 100 ng/ml could inhibit the cell proliferation significantly, and the apoptosis ratio in high dose of EGF group was higher than in control group. EGF could significantly induce a quick rise of intracellular free calcium, but the peak value of intracellular free calcium activated by high dose of EGF was higher than by low dose of EGF. It was suggested that EGF had a dual effect on gliomas: low dose of EGF could stimulate the cell proliferation of gliomas, but high dose of EGF could induce the cell apoptosis and inhibit the proliferation of gliomas, which might be contributed to the difference of intracellular free calcium.

Apoptosis↗
PubMed2006

Microsurgical experience with keyhole operations on intracranial aneurysms.

BACKGROUND: We report our experience with keyhole approaches as favorable treatments for various intracranial aneurysms including multiple aneurysms and giant aneurysms. METHODS: According to the different locations of 105 aneurysms harbored in 100 patients, different keyhole approaches were designed elaborately, among which a supraorbital keyhole approach was used in 91 cases, a pterional keyhole approach in 5 cases, a subtemporal keyhole approach in 3 cases, a retromastoid keyhole approach in 2 cases, and a unifrontal interhemispheric keyhole approach in 1 case. RESULTS: Among those 105 aneurysms, 99 were clipped successfully, including 4 that were resected after clipping. One mini-aneurysm was wrapped. The other aneurysms were trapped, including 1 VA aneurysm, 1 giant ICA aneurysm, 1 giant PCoA aneurysm, and 2 giant aneurysms in the PCAs (P2-P3 segment). Multiple aneurysms in 5 cases were treated in 1 surgical session, including 3 cases via unilateral approaches and 2 cases via bilateral approaches. There were no severe keyhole approach-related complications in this present series. CONCLUSION: The keyhole approaches, based on improvements in diagnostic imaging, advanced surgical instruments, and microsurgical skills, are effective and ideal craniotomy techniques in the hands of experienced neurosurgeons for the treatment of intracranial aneurysms, including multiple and giant aneurysms, in patients without diffuse SAH, severe cerebral vasospasm, and severe brain edema or brain swelling.

Adolescent↗
PubMed2006

Determination of specific CD4 and CD8 T cell epitopes after AAV2- and AAV8-hF.IX gene therapy.

The application of AAV2 or AAV8 vectors for delivery of human coagulation factor IX (hF.IX) is a promising gene therapy for hemophilia B. One major limitation of this therapy is the development of antibodies and a cytotoxic T lymphocyte (CTL) response against both the vector capsid and the transgene. We determined the class I and class II MHC peptide epitopes for AAV2, AAV8, and hF.IX after administration of AAV-2-hF.IX or AAV8-hF.IX in H2(b) (C57BL/6), H2(d) (BALB/c), or H2(k) (C3H) strains of mice. The results indicate that the AAV2 capsid peptide AA(373-381), the AAV8 capsid peptide AA(50-58), and the hF.IX transgene peptide AA(311-319) can elicit a CTL response as indicated by an IFN-gamma ELISPOT assay and an in vivo CTL assay. Furthermore, a strong H2(k) MHC II-restricted Th1 response can be elicited in C3H mice by the AAV8 capsid peptide AA(126-140) and the hF.IX peptide AA(108-122), whereas a strong Th2 response can be elicited by the AAV2 peptide AA(475-489). These results show that specific CTL responses are generated to both AAV capsid epitopes and hF.IX epitopes after injection of AAV-hF.IX, and MHC class II epitopes derived from AAV-hF.IX promote development of either Th1 or Th2 cells.

Amino Acid Sequence↗
PubMed2006

Biodegradation of petroleum hydrocarbons by two Pseudomonas aeruginosa strains with different uptake modes.

The uptake modes of alkanes by two strains (Pseudomonas aeruginosa S and Pseudomonas aeruginosa Y) were compared in this article. It was found that the strain of P. aeruginosa S showed low cell surface hydrophobicity and the surface tension of the broth decreased when the strain was cultivated on alkanes. On the contrary, P. aeruginosa Y showed higher cell surface hydrophobicity and the change in surface tension was not significant. This suggests that P. aeruginosa Y accessed hydrocarbon droplets by direct contact mode, while P. aeruginosa S engaged hydrocarbon droplets by biosurfactant-medium mode. The biodegradation of petroleum hydrocarbons by the two strains was also investigated. The results showed that irrespective of the substrate utilized: liquid hydrocarbons, solid hydrocarbons or crude oil in contaminated soil, the degradation by P. aeruginosa S was faster than that by P. aeruginosa Y. It was also deduced that the produced biosurfactant is advantageous in improving the biodegradation process.

Biodegradation, Environmental↗
PubMed2006

Order of photocatalytic degradation as ranked by critical photonic times (CPTs) indicates the composition of organic dye mixtures: selectivity of hydroxyl radicals.

A simple critical photonic time (CPT) ranking method for the simultaneous determination of known organic dyes in the industrial wastewater of different concentrations was developed. A kinetic-measure, CPT theory, was developed to discriminate between the dyes in the textile effluent solution. The CPTs were calculated and ranked 1-4 from the smallest to the largest. The ranks indicate the order in which the individual dyes in the effluents were photocatalytically degraded. The described procedure allowed us to monitor the decolorization kinetics of the dyes in mixtures of different concentrations, when subjected to immobilized TiO2 photocatalysis in the presence of H2O2 from the start (H2O2FS). The outcome of hydroxyl radical (HO*) attack was consistently specific and regioselective for the individual dyes in the textile effluent. To explain the effect of HO*, the order of degradation of Acid Orange 52 < Acid Yellow 36 < Acid Red 17 < Acid Blue 45 < polyvinyl alcohol (PVA) was inferred.

Coloring Agents↗
PubMed2006

In vivo analysis of adenovirus-specific cytotoxic T lymphocyte response in mice deficient in CD28, fas ligand, and perforin.

Adenoviruses (Ad) have been extensively studied as gene delivery vectors in gene therapy and as vaccine carriers. The cell-mediated cytotoxicity induced by Ad is of great interest in both applications. However, the mechanism underlying Ad-specific cytotoxic T lymphocyte (CTL) generation and effector function remains unclear. In this study, we used a novel MHC class I tetramer and an in vivo CTL assay to examine the role of CD28, perforin, Fas ligand (FasL), and TNF-alpha in the generation and function of Ad-specific CTLs in vivo. During the primary response, there was a significant defect in both the generation and in vivo effector function of Ad-specific CTLs in CD28-/- mice, but not in CD4+ T cell-depleted mice or CD4-/- mice. The relative role of CTL effector molecules was assayed by in vivo CTL assay in perforin- or FasL-mutant mice, using donor cells from Fas-deficient or TNFR1/TNFR2-deficient mice. The results indicated that the in vivo CTL activity is mediated mainly by perforin. In the absence of perforin, production of FasL, but not TNF-alpha, by the CTLs results in lower level Ad-specific killing of target cells. These results provide important implications concerning the development of safe and effective Ad vectors for gene therapy and vaccines.

Adenoviridae↗
PubMed2006

Significant increase of glycolytic flux in Torulopsis glabrata by inhibition of oxidative phosphorylation.

This study was aimed at increasing the glycolytic flux of the multivitamin-auxotrophic yeast Torulopsis glabrata by disturbing oxidative phosphorylation. We examined two different strategies to impede oxidative phosphorylation. The first strategy was disruption of the activity of the electron transfer chain (ETC), by either of two approaches. One was separately adding, at 10 mg L1, specific inhibitors of complex I (rotenone) or of the bc1 complex (antimycin A) to the culture broth of T. glabrata CCTCC M202019, which resulted in significantly decreased intracellular ATP levels (43% and 27.7%) and significantly increased rates of glucose consumption (qs) and pyruvate production (qp); another approach was breeding a respiratory-deficient mutant RD-16, in which cytochromes aa3 and b in the ETC were deleted after ethidium bromide mutagenesis, to reduce the ETC activity constitutively. The second strategy was inhibiting F0F1-ATP synthase with 0.05 mM oligomycin. Also, a neomycin-resistant mutant with 65% decreased F0F1-ATPase activity was studied. With the two strategies, the specific activity of phosphofructokinase (R2=0.9971), the average specific glucose consumption rate (R2=0.9967) and the average specific pyruvate production rate (R2=0.965) were closely correlated with the intracellular ATP level, all of them being increased at a lower intracellular ATP level.

Adenosine Triphosphate↗
PubMed2006

Digging behavior of Solenopsis invicta workers when exposed to contact insecticides.

ABSTRACT Contact between ants and insecticides is a prerequisite for contact insecticides to be effective in the control of red imported fire ants, Solenopsis invicta Buren. Typically, passive contact occurs in the insecticide application process, but ants also may actively contact insecticides by digging in treated soil or walking on a treated soil surface. Laboratory experiments were conducted to determine whether fire ant workers would dig sand treated with contact insecticides in two different scenarios: (1) no-choice bioassays where insecticide-treated sand was the only available digging substrate, and (2) two-choice bioassays where nontoxicant sand was also available for digging. Eight insecticides that are currently registered in the United States for imported fire ant control were tested. They include acephate, bifenthrin, carbaryl, cyfluthrin, deltamethrin, gamma-cyhalothrin, permethrin, and pyrethrin. Workers dug the treated sand for every insecticide tested, even at concentrations up to 10 times of the lowest lethal concentration (LLC) which caused 100% mortality in a toxicity bioassay. However, generally, insecticides significantly reduced the digging effort, even at a concentration that did not cause any significant mortality in the toxicity bioassay.

Animals↗
PubMed2006

Proliferation of endothelial cell on polytetrafluoroethylene vascular graft materials carried VEGF gene plasmid.

OBJECTIVE: To investigate whether vascular endothelial growth factor (VEGF) gene plasmid carried by polytetrafluoroethylene (PTFE) vascular graft materials could transfect endothelial cells (ECs) and promote their growth. METHODS: PTFE vascular graft materials carried with pCDI-hVEGF(121), pCDI or pEGFP were incubated in Tris-buffer solution and the values of optical density of 260 nm at different time were plotted, then the DNA controlled release curve was made. ECs derived from human umbilical vein were seeded on the pCDI-hVEGF(121)/pCDI/pEGFP-PTFE materials or tissue culture plates, ECs numbers were counted and VEGF protein concentrations at different time were measured by enzyme-linked immunoadsorbent assay method. Green fluorescent protein (GFP) expression in ECs on pEGFP-PTFE materials was examined with fluorescence microscopy. RESULTS: The controlled release curve showed that the gene released from PTFE materials was rapid within 8 h, then slowed down and that the gene released continuously even after 72 h. At 24, 72 and 120 h, ECs number and proliferation rate of pCDI-hVEGF(121)-PTFE materials were higher than those of pCDI or pEGFP-PTFE materials (P<0.05). VEGF protein concentration of pCDI-hVEGF(121)-PTFE materials was higher than that of pCDI or pEGFP-PTFE materials at 6, 24, 72 and 120 h (P<0.01). GFP expression in ECs on the pEGFP-PTFE materials could be detected by fluorescence microscopy. CONCLUSION: PTFE graft can be used as a carrier of VEGF gene plasmid, VEGF gene carried by PTFE can transfect ECs and promote ECs growth.

Blood Vessel Prosthesis↗
PubMed2006

Simultaneous nitrification and denitrification in an aerobic reactor with granular sludge originating from an upflow anaerobic sludge bed reactor.

Anaerobic granular sludge, obtained from an upflow anaerobic sludge bed reactor at a brewery waste treatment station, was cultured for 3 months under aeration conditions until the diameter of sludge was in the range 1.8 to 2.6 mm. The aerobic granular sludge gathered acquired the ability of catalyzing simultaneous nitrification and denitrification (SND) and was applied in the study of the process of nitrogen removal in a bioreactor. The ratio between chemical oxygen demand (COD) and ammonium-nitrogen (NH4(+)-N) concentration in the influent was found to be an important factor influencing the process of SND. The final percentage removal of NH4(+)-N reached 100% under the optimal condition of 500 mg/L COD and 0.39 NH4(+)-N/COD. Intermediate products, such as nitrite-nitrogen and nitrate-nitrogen, were also analyzed to clarify the SND process with the aerobic granular sludge.

Ammonia↗
PubMed2006

Conus medullaris schistosomiasis.

OBJECT: The authors performed a study to investigate the clinical manifestations, treatment strategies, and possible pathogenesis of conus medullaris schistosomiasis. METHODS: Six cases collected from the authors' experience and four cases reported in the literature were studied retrospectively for clinical manifestations, treatment outcomes, and prognosis. All patients experienced progressive lower-extremity weakness and functional bowel and bladder impairment. Although the magnetic resonance (MR) imaging results suggested the presence of a conus medullaris tumor, schistosomiasis was diagnosed based on pathological results obtained in the 10 patients. The results of surgery followed by pyquiton and hormone treatment confirmed the diagnosis, and the patients' prognoses were good. CONCLUSIONS: This pathological entity is predominantly found in adults, and the clinical manifestations have no specificity, although the MR imaging may provide some clues. As a form of ectopic schistosomiasis, conus medullaris schistosomiasis deserves special consideration and further exploration. If an early diagnosis can be made and pyquiton and hormone therapy is given, surgery can be avoided and the prognosis will remain good.

Adult↗
PubMed2006

Gene rearrangement and comparative genomic hybridization studies of classic Hodgkin lymphoma expressing T-cell antigens.

CONTEXT: Reed-Sternberg cells in classic Hodgkin lymphoma are enigmatic and difficult to study because they are so sparse. Tissue microdissection allows for the isolation of single Reed-Sternberg cells. Isolated Reed-Sternberg cells show clonal immunoglobulin gene rearrangement indicating a B-cell origin. Rarely, Reed-Sternberg cells in classic Hodgkin lymphoma express T-cell antigens, suggesting a possible T-cell origin. OBJECTIVE: To determine whether there is a difference in genotype between classic Hodgkin lymphoma and classic Hodgkin lymphoma expressing T-cell antigens and to document T-cell clonality. DESIGN: We studied 4 cases of Hodgkin lymphoma with a characteristic phenotype and immunoreactivity for CD2 and CD3. Single CD30+ Reed-Sternberg cells from each case were isolated by laser capture microdissection for immunoglobulin heavy chain and T-cell receptor-gamma genes by polymerase chain reaction studies. Comparative genomic hybridization was performed in all cases. RESULTS: Two of 4 cases showed clonal rearrangement of the T-cell receptor-gamma; none showed immunoglobulin heavy chain rearrangement. Two control cases were negative for T cell receptor-gamma but 1 showed immunoglobulin heavy chain rearrangement. Comparative genomic hybridization analysis revealed significant overlap in genomic alteration in Hodgkin lymphoma cases regardless of genotype or phenotype and several regions of imbalance specific to CD3+ Hodgkin lymphoma cases. All patients are alive with no evidence of disease from 10 to 44 months. CONCLUSIONS: Our findings suggest that a T-cell phenotype classic Hodgkin lymphoma can be supported by genotypic studies and that there may be cytogenetic differences between classic Hodgkin lymphoma and Hodgkin lymphoma expressing T-cell antigens.

Adolescent↗
PubMed2006

[Characteristics of aerobic granular sludge membrane bioreactor for wastewater treatment].

Characteristics of aerobic granular sludge membrane bioreactor (MBR) and the membrane fouling were studied with synthetic wastewater. Experimental results showed that COD removal rate could be reached over 96% under the conditions of HRT = 6h, DO 4 - 6 mg x L(-1) and the volumetric load of COD = 7.24 kg x (m3 x d)(-1). When the volumetric load of NH3-N was 0.17 kg x (m3 x d)(-1), the removal rate of NH3-N was about 60%. The variations of the COD/N ratio could not affect the removal of COD and NH3-N. During the stable operation process, MLSS of the reactor was as high as 14 - 16 mg x L(-1), which could conduce simultaneous nitrification-denitrification, as the anoxic and anaerobic microorganisms might be existed in the core of granular sludge. In addition, the membrane flux of MBR of two different configurations of sludge, granular sludge and floccular sludge, was compared. The flux reduction of granular sludge MBR was much lower than that of floccular sludge MBR. Moreover, the membrane permeability of the granular sludge MBR could be regained simply by backwashing with aeration or washing the membrane with water.

Bacteria, Aerobic↗
PubMed2006

[Effect of pentachlorophenol (PCP) on bacterial community of an aerobic granular sludge estimated by T-RFLP].

Effect of pentachlorophenol (PCP) on COD and ammonium removal rates was investigated, and also changes of bacterial community within aerobic granular sludge were monitored by terminal restriction fragment length polymorphism (T-RFLP) technique. Compared with the removal rate of COD, the rate of ammonium removal is more sensitive to PCP. As the ammonium and COD removal rates decreased consistently, the bacterial genera within the aerobic granular sludge also decrease with the increase of PCP concentration. According to the response of PCP, the bacteria could be categorized into four groups as follows: (1) The most sensitive organisms such as Microbacterium, Streptococcus and two new kinds of microorganisms; (2) The more sensitive microorganisms such as Corynebacterium, Nevskia. and another unreported bacterium; (3) The lower sensitive organisms encompassing Mycoplasma, Exiguobacterium, and another microorganism which has not been reported yet; (4) The PCP-tolerant organisms, including microorganisms indicated by 13 TRFs are represented as 69, 71, 82, 175, 198, 241, 229, 232, 233, 240, 245, 269 and 449bp. To most noticeable, TRF relative areas of the microorganisms indicated by TRFs 82 bp and 175 bp achieve 22.7% and 13%, respectively, and become predominant within the aerobic granular sludge with the PCP concentration at 30 mg/L.

Bacteria, Aerobic↗
PubMed2006

Comparative observation of protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure.

OBJECTIVE: To explore the protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure (BUP). METHODS: The hearing thresholds of the guinea pigs were assessed with auditory brainstem responses (ABR). The traumatic levels of tympanic membrane and ossicular chain were observed under stereo-microscope. The rate of outer hair cells (OHCs) loss was analyzed using a light microscope. The changes of guinea pigs protected with barrel and earplug were compared with those of the control group without any protection. RESULTS: An important ABR threshold shift of the guinea pigs without any protection was detected from 8h to 14d after being exposed to BUP with a peak ranging from -64.5 kPa to -69.3 kPa ( P<0.01). The rate of perforation of tympanic membrane reached 87.5% and that of total OHCs loss was 19.46% +/- 5.38% at 14d after exposure. The guinea pigs protected with barrel and earplug had lower ABR threshold and total OHCs loss rate compared with the animals without any protection (P<0.01). All of the tympanic membrane and ossicular chain of the protected animals maintained their integrities. Meanwhile, the guinea pigs protected with the barrel had lower ABR threshold and total OHCs loss rate than those with earplug (P<0.01). CONCLUSIONS: The earplug and barrel have protective effects against BUP-induced trauma on auditory organs of the guinea pigs and the protective effects of barrel are better than those of earplug.

Animals↗
PubMed2006

[Spatial-temporal dynamic change of land resource degradation in China].

Large scale spatial and temporal land use survey data were used to study the dynamics of land use change in China recently. With the aid of GIS, the spatial-temporal dynamic change of land resource degradation at the national level was investigated using authoritative datasets from detailed land use surveys (early 1990s approximately 2003). As a result, seven major types of land degradation processes were identified, including sandy desertification, rocky desertification, secondary salinification, non-agricultural land occupation, deforestation, natural grassland degradation and wetlands shrinking. This paper comprehensively explored the characteristics of these land degradation processes and revealed the status and trend of the holistic land resource degradation in China. Results shows that: (1) Although land degradation has been controlled in local area, but it is still continuing to spread in the whole country. The total degradation index of the holistic land resource presented fluctuating trend. Indexes of non-agricultural construction occupation and wetland shrinking process are far more than that of other process, which are two primary causes contribution to heading straight towards full-scale land resource deterioration in China. (2) Land resource degradation process of China focused on natural grass land, and non-agricultural construction land, which attained 66.27%; Land resource degradation rehabilitation mainly focused on desertification and forest restoration, which accounts for 57.5%. (3) Sandy desertification and rocky desertification process have been reversing greatly. The total net change of their quantities was decreased by 15,578km2. But most of the rehabilitation of land desertification was concentrated on the originally ecological vulnerable northwestern zone, whereas newly added desertified land has been expanding and aggravating in eastern zone, especially around river watersheds. (4) Over two-thirds of non-agriculture land expansion came from cultivated land. In addition, almost 60 percent of the loss cultivated land occupied by non-agricultural land was appeared in the Northeast, the Eastern coast and Central China where have many high productive agricultural lands of China. This kind of land degradation has threatened food security of China seriously. (5) However, large scale reclamation of ecological land transferred into cultivated land was the most dominant factor of degradation. For example, the conversion of wetland resource to croplands by reclamation accounts for over 50 percent of wetland shrinking.

Agriculture↗