| 1. |
- Li, Jing-Jing, et al.
(författare)
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Immobilized Triton X-100-assisted refolding of Green Fluorescent Protein-Tobacco Etch Virus protease fusion protein using β-cyclodextrin as the eluent
- 2009
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113 .- 1873-3298. ; 44:3, s. 277-282
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Tidskriftsartikel (refereegranskat)abstract
- A new protein refolding technique based on the use of the non-charged detergent Triton X-100 immobilized to the cross-linked agarose gel Sepharose High Performance has been developed. The new solid phase was used in combination with soluble β-cyclodextrin (β-CD) to refold recombinant Green Fluorescent Protein fused to Tobacco Etch Virus protease (GFPTEVP) expressed as inclusion bodies in E. coli. Previous attempts to refold recombinant GFPTEVP by dilution had failed. In the new procedure a column packed with Triton X-100-coupled Sepharose High Performance was used to capture unfolded GFPTEVP followed by elution using an increasing β-CD concentration gradient. The yield of properly refolded GFPTEVP was 46% at a protein concentration of 380 μg/ml. In contrast, dilution refolding of GFPTEVP at 200 μg/ml refolding buffer resulted in only 4.7% of native protein.
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| 2. |
- Alderman, J. McKee, et al.
(författare)
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Neuroendocrine inhibition of glucose production and resistance to cancer in dwarf mice
- 2009
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Ingår i: Experimental Gerontology. - : Elsevier BV. - 0531-5565 .- 1873-6815. ; 44:1-2, s. 26-33
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Tidskriftsartikel (refereegranskat)abstract
- Pit1 null (Snell dwarf) and Proph1 null (Ames dwarf) mutant mice lack GH, PRL and TSH. Snell and Ames dwarf mice also exhibit reduced IGF-I, resistance to cancer and a longer lifespan than control mice. Endogenous glucose production during fasting is reduced in Snell dwarf mice compared to fasting control mice. In view of cancer cell dependence on glucose for energy, low endogenous glucose production may provide Snell dwarf mice with resistance to cancer. We investigated whether endogenous glucose production is lower in Snell dwarf mice during feeding. Inhibition of endogenous glucose production by glucose injection was enhanced in 12 to 14 month-old female Snell dwarf mice. Thus, we hypothesize that lower endogenous glucose production during feeding and fasting reduces cancer cell glucose utilization providing Snell dwarf mice with resistance to cancer. The elevation of circulating adiponectin, a hormone produced by adipose tissue, may contribute to the suppression of endogenous glucose production in 12 to 14 month-old Snell dwarf mice. We compared the incidence of cancer at time of death between old Snell dwarf and control mice. Only 18% of old Snell dwarf mice had malignant lesions at the time of death compared to 82% of control mice. The median ages at death for old Snell dwarf and control mice were 33 and 26 months, respectively. By contrast, previous studies showed a high incidence of cancer in old Ames dwarf mice at the time of death. Hence, resistance to cancer in old Snell dwarf mice may be mediated by neuroendocrine factors that reduce glucose utilization besides elevated adiponectin, reduced IGF-I and a lack of GH, PRL and TSH, seen in both Snell and Ames dwarf mice. Proteomics analysis of pituitary secretions from Snell dwarf mice confirmed the absence of GH and PRL, the secretion of ACTH and elevated secretion of Chromogranin B and Secretogranin II. Radioimmune assays confirmed that circulating Chromogranin B and Secretogranin II were elevated in 12 to 14 month-old Snell dwarf mice. In summary, our results in Snell dwarf mice suggest that the pituitary gland and adipose tissue are part of a neuroendocrine loop that lowers the risk of cancer during aging by reducing the availability of glucose.
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| 3. |
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| 4. |
- Chen, Yifeng, et al.
(författare)
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Modeling coupled THM processes of geological porous media with multiphase flow : Theory and validation against laboratory and field scale experiments
- 2009
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Ingår i: Computers and geotechnics. - : Elsevier BV. - 0266-352X .- 1873-7633. ; 36:8, s. 1308-1329
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Tidskriftsartikel (refereegranskat)abstract
- A FEM model for analysis of fully coupled multiphase flow, thermal transport and stress/deformation in geological porous media was developed based on the momentum, mass and energy conservation laws of the continuum mechanics and the averaging approach of the mixture theory over a three phase (solid-liquid-gas) system. Six processes (i.e. stress-strain, water flow, gas flow, vapor flow, heat transport and porosity evolution processes) and their coupling effects are considered, which not only makes the problem well-defined, but renders the governing PDEs closed, complete. compact and compatible. Displacements, pore water pressure, pore gas pressure, pore vapor pressure, temperature and porosity are selected as basic unknowns. The physical phenomena such as phase transition, gas solubility in liquid, thermo-osmosis, moisture transfer and moisture swelling are modeled. As a result, the relative humidity and other related variables in porous media can be evaluated on a sounder physical basis. A three dimensional computer code, THYME3D, was developed, with eight degrees of freedom at each node. The laboratory CEA Mock-up test and the field scale FEBEX benchmark test on bentonite performance assessment for underground nuclear waste repositories were used to validate the numerical model and the software. The coupled THM behaviors of the bentonite barriers were satisfactorily simulated, and the effects and impacts of the governing equations, constitutive relations and property parameters on the coupled THM processes were understood in terms of more straightforward interpretation of physical processes at microscopic scale of the porous media. The work developed enables further in-depth research on fully coupled THM or THMC processes in porous media.
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| 5. |
- Chen, Y., et al.
(författare)
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Numerical model for fully coupled THM processes with multiphase flow and code validation
- 2009
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Ingår i: Chinese Journal of Rock Mechanics and Engineering. - 1000-6915. ; 28:4, s. 649-665
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Tidskriftsartikel (refereegranskat)abstract
- A numerical model for fully coupled THM processes with multiphase flow in porous media was developed based on the momentum, mass and energy conservation laws of the continuum mechanics and the averaging approach of the mixture theory over a solid-liquid-gas three-phase system. To characterize multiphase THM coupling and to make the governing equations closed, complete and compatible, six processes and their coupling effects were considered, including stress-strain, water flow, gas flow, vapor flow, heat transport and porosity evolution processes. The physical phenomena such as phase transition, gas solubility in liquid, thermo-osmosis, moisture transfer and moisture swelling were modeled. As a result, the relative humidity of pore gas was defined on a sounder physical basis, avoiding the traditional definition as a negative exponential function of suction and absolute temperature. By selecting displacements, pore water pressure, pore gas pressure, pore vapor pressure, temperature and porosity as basic unknown variables, a finite element formulation was then established, and a three-dimensional computer code, THYME3D, was developed, with each node of 8 degrees of freedom. The bentonite THM Mock-up experiments performed by CEA were employed to validate the mathematical model and the software. The main coupling mechanisms involved in the experiments were satisfactorily simulated in the validation, and the effects of the governing equations, the constitutive relations and the parameters on the coupled THM processes were understood. The work developed enabled further in-depth research on fully coupled THM or THMC processes in porous media.
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| 6. |
- Di, Jing, et al.
(författare)
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A novel composite electrolyte based on CeO2 for low temperature solid oxide fuel cells
- 2008
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Ingår i: Journal of Inorganic Materials. - 1000-324X. ; 23:3, s. 573-577
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Tidskriftsartikel (refereegranskat)abstract
- A novel composite material based on mixture of samarium-doped ceria (SDC)-carbonate was studied as electrolyte in low temperature solid oxide fuel cells. The phase and microstructures of composite electrolyte were examined by XRD and SEM. The electrical conductivity was investigated by AC impedance spectroscopy at 400-700 degrees C in different atmospheres. An abrupt change in the conductivity at about 500 degrees C indicates that different mechanisms affect transfer in different temperature ranges. The conductivity increases with the carbonate fraction above 500 degrees C. The conductivity in reduce atmosphere is higher than that in oxide atmosphere. An anode-supported fuel cell using SDC-carbonate as electrolyte was fabricated and tested. The result shows that all the composite electrolytes exhibit better performance than pure SDC electrolyte. The electrolyte with 20wt% carbonate can achieve the highest power density of 415mW center dot cm(-2) and an open circuit voltage of 1.00V at 500 degrees C.
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| 7. |
- Hua, Dong, et al.
(författare)
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Small interfering RNA-directed targeting of toll-like receptor 4 inhibits human prostate cancer cell invasion, survival, and tumorigenicity
- 2009
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 46:15, s. 2876-2884
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Tidskriftsartikel (refereegranskat)abstract
- A major cause of tumor treatment failure is cancer cell metastasis. Toll-like receptor 4 (TLR4)-mediated signaling has been implicated in tumor cell invasion, survival, and metastasis in a variety of cancers. In this study, we investigated the biological roles of TLR4 in prostate metastatic cell invasion and survival, and the potential of gene silencing of TLR4 using small interfering RNA (siRNA) for treatment of cancer. In cultured human prostate cancer cell lines, TLR4 were higher PC3 and DU145 as compared with the poorly metastatic LNCaP indicating that up-regulation of TLR4 was positively correlated with metastasis of tumor cell. In the highly metastatic cancer cell PC3, gene silencing of TLR4 using siRNA significantly inhibited TLR4 mRNA expression and protein level. Knockdown of TLR4 in PC3 cells resulted in a dramatic reduction of tumor cell migration and invasion as indicated by a Matrigel invasion assay. Furthermore, TLR4 siRNA suppressed cell viability and ultimately caused the induction of apoptotic cell death. The effects were associated with abrogating TLR4-mediated signaling to downstream target molecules such as myeloid differentiation factor 88 (MyD88), adaptor-inducing IFN-beta (TRIF), and interferon regulatory factor-1 (IRF-1). In a mouse prostate cancer model, administration with the plasmid construct expressing siRNA for TLR4 obviously inhibited established tumor growth and survival. These studies revealed evidence of a multifaceted signaling network operating downstream of TLR4-mediated tumor cell invasion, proliferation, and survival. Thus, RNA interference-directed targeting of TLR4 may raise the potential of its application for cancer therapy.
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| 8. |
- Jang, Sung-Wuk, et al.
(författare)
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Serine/arginine protein-specific kinase 2 promotes leukemia cell proliferation by phosphorylating acinus and regulating cyclin A1
- 2008
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Ingår i: Cancer Research. - 1538-7445 .- 0008-5472. ; 68:12, s. 4559-4570
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Tidskriftsartikel (refereegranskat)abstract
- Serine/arginine (SR) protein-specific kinase (SRPK), a family of cell cycle-regulated protein kinases, phosphorylate SR domain-containing proteins in nuclear speckles and mediate the pre-mRNA splicing. However, the physiologic roles of this event in cell cycle are incompletely understood. Here, we show that SRPK2 binds and phosphorylates acinus, an SR protein essential for RNA splicing, and redistributes it from the nuclear speckles to the nucleoplasm, resulting in cyclin A1 but not A2 up-regulation. Acinus S422D, an SRPK2 phosphorylation mimetic, enhances cyclin A1 transcription, whereas acinus S422A, an unphosphorylatable mutant, blocks the stimulatory effect of SRPK2. Ablation of acinus or SRPK2 abrogates cyclin A1 expression in leukemia cells and arrest cells at G, phase. Overexpression of acinus or SRPK2 increases leukemia cell proliferation. Furthermore, both SRPK2 and acinus are overexpressed in some human acute myelogenous leukemia patients and correlate with elevated cyclin A1 expression levels, fitting with the oncogenic activity of cyclin A1 in leukemia. Thus, our findings establish a molecular mechanism by which SR splicing machinery regulates cell cycle and contributes to leukemia tumorigenesis.
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| 9. |
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| 10. |
- Li, Liangxing, et al.
(författare)
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熔融液滴与冷却剂相互作用实验中液滴释放控制机构的研制
- 2008
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Ingår i: Hedongli Gongcheng. - ChengDu, China. - 0258-0926. ; 29, s. 42-45
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Tidskriftsartikel (refereegranskat)abstract
- 在高温熔融液滴与冷却剂相互作用的实验中,熔融液滴的释放控制对整个实验起至关重要的作用。本文在以往实验机械控制装置的基础上,自主设计一个自动控制电路来代替人工机械操作,利用控制电路给电磁铁提供瞬时脉冲来控制液滴瞬时释放下落,简化实验的可持续性操作,提高实验的重复性、精确性和操作方便性。
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