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| 2. |
- 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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| 6. |
- Fang, Evandro F., et al.
(författare)
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A research agenda for ageing in China in the 21st century (2nd edition): Focusing on basic and translational research, long-term care, policy and social networks.
- 2020
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Ingår i: Ageing Research Reviews. - : Elsevier BV. - 1568-1637. ; 64
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Tidskriftsartikel (refereegranskat)abstract
- One of the key issues facing public healthcare is the global trend of an increasingly ageing society which continues to present policy makers and caregivers with formidable healthcare and socio-economic challenges. Ageing is the primary contributor to a broad spectrum of chronic disorders all associated with a lower quality of life in the elderly. In 2019, the Chinese population constituted 18 % of the world population, with 164.5 million Chinese citizens aged 65 and above (65+), and 26 million aged 80 or above (80+). China has become an ageing society, and as it continues to age it will continue to exacerbate the burden borne by current family and public healthcare systems. Major healthcare challenges involved with caring for the elderly in China include the management of chronic non-communicable diseases (CNCDs), physical frailty, neurodegenerative diseases, cardiovascular diseases, with emerging challenges such as providing sufficient dental care, combating the rising prevalence of sexually transmitted diseases among nursing home communities, providing support for increased incidences of immune diseases, and the growing necessity to provide palliative care for the elderly. At the governmental level, it is necessary to make long-term strategic plans to respond to the pressures of an ageing society, especially to establish a nationwide, affordable, annual health check system to facilitate early diagnosis and provide access to affordable treatments. China has begun work on several activities to address these issues including the recent completion of the of the Ten-year Health-Care Reform project, the implementation of the Healthy China 2030 Action Plan, and the opening of the National Clinical Research Center for Geriatric Disorders. There are also societal challenges, namely the shift from an extended family system in which the younger provide home care for their elderly family members, to the current trend in which young people are increasingly migrating towards major cities for work, increasing reliance on nursing homes to compensate, especially following the outcomes of the ‘one child policy’ and the ‘empty-nest elderly’ phenomenon. At the individual level, it is important to provide avenues for people to seek and improve their own knowledge of health and disease, to encourage them to seek medical check-ups to prevent/manage illness, and to find ways to promote modifiable health-related behaviors (social activity, exercise, healthy diets, reasonable diet supplements) to enable healthier, happier, longer, and more productive lives in the elderly. Finally, at the technological or treatment level, there is a focus on modern technologies to counteract the negative effects of ageing. Researchers are striving to produce drugs that can mimic the effects of ‘exercising more, eating less’, while other anti-ageing molecules from molecular gerontologists could help to improve ‘healthspan’ in the elderly. Machine learning, ‘Big Data’, and other novel technologies can also be used to monitor disease patterns at the population level and may be used to inform policy design in the future. Collectively, synergies across disciplines on policies, geriatric care, drug development, personal awareness, the use of big data, machine learning and personalized medicine will transform China into a country that enables the most for its elderly, maximizing and celebrating their longevity in the coming decades. This is the 2nd edition of the review paper (Fang EF et al., Ageing Re. Rev. 2015).
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| 7. |
- Fu, Yongshuo H., et al.
(författare)
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Soil moisture regulates warming responses of autumn photosynthetic transition dates in subtropical forests
- 2022
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 28:16, s. 4935-4946
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Tidskriftsartikel (refereegranskat)abstract
- Autumn phenology plays a key role in regulating the terrestrial carbon and water balance and their feedbacks to the climate. However, the mechanisms underlying autumn phenology are still poorly understood, especially in subtropical forests. In this study, we extracted the autumn photosynthetic transition dates (APTD) in subtropical China over the period 2003–2017 based on a global, fine-resolution solar-induced chlorophyll fluorescence (SIF) dataset (GOSIF) using four fitting methods, and then explored the temporal–spatial variations of APTD and its underlying mechanisms using partial correlation analysis and machine learning methods. We further predicted the APTD shifts under future climate warming conditions by applying process-based and machine learning-based models. We found that the APTD was significantly delayed, with an average rate of 7.7 days per decade, in subtropical China during 2003–2017. Both partial correlation analysis and machine learning methods revealed that soil moisture was the primary driver responsible for the APTD changes in southern subtropical monsoon evergreen forest (SEF) and middle subtropical evergreen forest (MEF), whereas solar radiation controlled the APTD variations in the northern evergreen-broadleaf deciduous mixed forest (NMF). Combining the effects of temperature, soil moisture and radiation, we found a significantly delayed trend in APTD during the 2030–2100 period, but the trend amplitude (0.8 days per decade) was much weaker than that over 2003–2017. In addition, we found that machine learning methods outperformed process-based models in projecting APTD. Our findings generate from different methods highlight that soil moisture is one of the key players in determining autumn photosynthetic phenological processes in subtropical forests. To comprehensively understand autumn phenological processes, in-situ manipulative experiments are urgently needed to quantify the contributions of different environmental and physiological factors in regulating plants' response to ongoing climate change.
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| 8. |
- Li, Jing-Jing, et al.
(författare)
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A mild hydrophobic interaction chromatography involving polyethylene glycol immobilized to agarose media refolding recombinant Staphylococcus aureus elongation factor G
- 2005
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Ingår i: Protein Expression and Purification. ; 40:2, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- Recombinant Staphylococcus aureus elongation factor G (EF-G) is difficult to refold by dilution due to the formation of large amounts of misfolded structures. However, refolding of EF-G by adsorption to a chromatographic column packed with immobilized polyethylene glycol 20,000 (PEG 20 K) followed by pulse elution with 8 M urea resulted in 88% mass recovery and 80% of correctly refolded structure. The PEG 20 K was coupled to brominated allyl group derivatized Sepharose High Performance to construct a mild hydrophobic adsorbent. Various other hydrophobic interaction adsorbents were also attempted to refold EF-G. However, ligands with high hydrophobicity tended to misfold EF-G, resulting in irreversible adsorption. Various solvents, detergents, and low temperature as well as 8 M urea were tried to release bound EF-G. Only pulse elution with 8 M urea was efficient. Urea concentrations favorable for efficiently refolding EF-G were investigated. Low urea concentration produced more misfolded structures.
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| 9. |
- Li, Jing-Jing, et al.
(författare)
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Immobilized β-cyclodextrin polymer coupled to agarose gel properly refolding recombinant Staphylococcus aureus elongation factor-G in combination with detergent micelle
- 2006
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Ingår i: Protein Expression and Purification. ; 45:1, s. 72-79
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Tidskriftsartikel (refereegranskat)abstract
- A novel artificial chaperone system using a combination of interactions between the unfolded protein, a detergent and a chromatographic column packed with immobilized β-cyclodextrin (β-CD) polymer coupled to an agarose gel, was introduced to refold recombinant Staphylococcus aureus elongation factor-G (EF-G). Pre-mixing of 10% Triton X-100 and unfolded EF-G at 24 mg/ml followed by a 20-fold dilution into refolding buffer led to successful capturing of EF-G by Triton X-100 resulting in formation of a detergent–protein complex at 1.2 mg/ml of final protein concentration. The complex was subsequently applied to the immobilized β-CD polymer column resulting in correct refolding of EF-G at a concentration of 530 μg/ml with 99% mass recovery. Detergent concentrations above critical micelle concentration were required for efficient capturing of EF-G at high protein concentration. Other detergents with hydrophile–lipophile-Balance values similar to that of Triton X-100 (Triton N-101, Noindet P40 (NP40), and Berol 185) also produced similar result. Soluble polymerized β-CD was more efficient than the monomer to remove the detergent from the protein complex in a batch system. Immobilized β-CD polymer column further improved the capability of detergent removal and was able to prevent aggregation that occurred with the addition of soluble β-CD polymer at high protein concentration in the batch system. The mechanism for this system-assisted refolding was tentatively interpreted: the released protein could correctly refold in an enclosed hydrophilic environment provided by the integration of matrix and β-CD polymer, and thus avoided aggregation during detergent removal.
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| 10. |
- Su, Linjia, et al.
(författare)
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GRP75-driven, cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca2+ nanoparticles underlies distinct gene therapy effect in ovarian cancer
- 2022
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Ingår i: Journal of Nanobiotechnology. - : Springer Nature. - 1477-3155. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Practice of tumor-targeted suicide gene therapy is hampered by unsafe and low efficient delivery of plasmid DNA (pDNA). Using HIV-Tat-derived peptide (Tat) to non-covalently form Tat/pDNA complexes advances the delivery performance. However, this innovative approach is still limited by intracellular delivery efficiency and cell-cycle status. In this study, Tat/pDNA complexes were further condensed into smaller, nontoxic nanoparticles by Ca2+ addition. Formulated Tat/pDNA-Ca2+ nanoparticles mainly use macropinocytosis for intercellular delivery, and their macropinocytic uptake was persisted in mitosis (M-) phase and highly activated in DNA synthesis (S-) phase of cell-cycle. Over-expression or phosphorylation of a mitochondrial chaperone, 75-kDa glucose-regulated protein (GRP75), promoted monopolar spindle kinase 1 (MPS1)-controlled centrosome duplication and cell-cycle progress, but also driven cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca2+ nanoparticles. Further in vivo molecular imaging based on DF (Fluc-eGFP)-TF (RFP-Rluc-HSV-ttk) system showed that Tat/pDNA-Ca2+ nanoparticles exhibited highly suicide gene therapy efficiency in mouse model xenografted with human ovarian cancer. Furthermore, arresting cell-cycle at S-phase markedly enhanced delivery performance of Tat/pDNA-Ca2+ nanoparticles, whereas targeting GRP75 reduced their macropinocytic delivery. More importantly, in vivo targeting GRP75 combined with cell-cycle or macropinocytosis inhibitors exhibited distinct suicide gene therapy efficiency. In summary, our data highlight that mitochondrial chaperone GRP75 moonlights as a biphasic driver underlying cell-cycle-dependent macropinocytosis of Tat/pDNA-Ca2+ nanoparticles in ovarian cancer.
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