| 1. |
- Carlsson, Jörgen, et al.
(författare)
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Conjugate chemistry and cellular processing of EGF-dextran
- 1999
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Ingår i: Acta Oncologica. - 0284-186X .- 1651-226X. ; 38:3, s. 313-321
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Tidskriftsartikel (refereegranskat)abstract
- Conjugates with specific binding to the epidermal growth factor receptor, EGFR, of interest for radionuclide based imaging and therapy were prepared using mouse epidermal growth factor, mEGF, and dextran. In one type of conjugate, mEGF was coupled to dextran by reductive amination in which the free amino group on the mEGF N-terminal reacted with the aldehyde group on the reductive end of dextran. The end-end coupled conjugate could be further activated by the cyanopyridinium agent CDAP, thereby introducing tyrosines to the dextran part. In the other type of conjugate, the cyanylating procedure using CDAP was applied, first to activate dextran and then allowing for the amino terminus of mEGF to randomly attach to the dextran. In the latter case, radionuclide-labelled tyrosines or glycines could be added in the same conjugation step. All types of mEGF-dextran conjugates had EGFR-specific binding since the binding could be displaced by an excess of non-radioactive mEGF. The conjugates were to a large extent internalized in the test cells and the associated radioactivity was retained intracellularly for different times depending on both the type of cells and conjugate applied. Different intracellular 'traffic routes' for the radionuclides are discussed as well as applications for both imaging and therapy.
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| 2. |
- Li, Bo, et al.
(författare)
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Joint IT and Spectrum Resource Load Balancing for VNF Selection in Inter-Datacenter Elastic Optical Networks
- 2017
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Ingår i: 2017 16TH INTERNATIONAL CONFERENCE ON OPTICAL COMMUNICATIONS & NETWORKS (ICOCN 2017). - : IEEE. - 9781538632734
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Konferensbidrag (refereegranskat)abstract
- The selection of virtualized network functions (VNFs) in service provisioning is a critical issue in inter-datacenter elastic optical networks. In this paper, considering load balancing of IT and spectrum resources, we propose two joint balancing factors, i.e., Global Balancing factor (GB factor) and Local Balancing factor (LB-factor) for VNFs selection. Then a Joint-Optimization Selection (JOS) algorithm is designed based on the joint balancing factors. Simulation results show that GB-factor based JOS can achieve better performance compared with LB-factor based JOS and benchmark algorithm.
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| 3. |
- Li, Furong, et al.
(författare)
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Modern pollen–€“climate relationships in north Xinjiang, northwestern China : Implications for pollen-based reconstruction of Holocene climate
- 2017
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Ingår i: The Holocene. - : Sage Publications. - 0959-6836 .- 1477-0911. ; 27:7, s. 951-966
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Tidskriftsartikel (refereegranskat)abstract
- Fossil pollen records are widely used to reconstruct past climate. Such reconstructions require that the relationships between pollen assemblages, vegetation, and climate are well understood. These can be studied in present circumstances given we assume that modern vegetation and climate are analogous to past ones. In this study, we analyze pollen–vegetation–climate relationships in the Jungar desert and Altay Mountains, northwestern China, a region for which careful reconstruction of past climate is needed to answer unsolved questions on past climate in an area located at the boundary between two different climate regimes (westerlies and monsoon). We use a dataset of 66 surface pollen samples from forest, meadow, steppe, and desert vegetation and six related climate variables, Tann, TJan, TJul, Pann, PJan, and PJul. Principal components analysis, redundancy analysis, Monte Carlo permutation tests, and variation partitioning are applied to quantify these relationships. We also assess pollen ratios as indices of aridity. We find that (1) Pann is the major climatic factor influencing pollen assemblages, followed by PJul, (2) the two variables are not correlated, and (3) the shared effect of (1) PJan and PJul, (2) PJan and Pann, (3) PJul and Tann, and (4) Tann, TJan, and TJul explains a larger portion of the variation in pollen data than the individual effect of each variable. Therefore, robust pollen–climate transfer functions can be developed for Pann and PJul, and several climate variables treated in combination. Artemisia/Chenopodiaceae is a strong index of aridity and Artemisia/Gramineae might be a useful index of Pann and PJul.
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| 4. |
- Li, Furong, et al.
(författare)
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Towards quantification of Holocene anthropogenic land-cover change in temperate China : A review in the light of pollen-based REVEALS reconstructions of regional plant cover
- 2020
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Ingår i: Earth-Science Reviews. - : Elsevier. - 0012-8252 .- 1872-6828. ; 203, s. 1-25
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Forskningsöversikt (refereegranskat)abstract
- In an attempt to quantify Holocene anthropogenic land-cover change in temperate China, we 1) applied the REVEALS model to estimate plant-cover change using 94 pollen records and relative pollen productivity for 27 plant taxa, 2) reviewed earlier interpretation of pollen studies in terms of climate- and human-induced vegetation change, and 3) reviewed information on past land use from archaeological studies. REVEALS achieved a more realistic reconstruction of plant-cover change than pollen percentages in terms of openland versus woodland. The study suggests successive human-induced changes in vegetation cover. The first signs of human-induced land-cover change (crop cultivation, otherwise specified) are found c. 7 ka BP in the temperate deciduous forest, and S and NE Tibetan Plateau (mainly grazing, possibly crop cultivation), 6.5-6 ka BP in the temperate steppe and temperate desert (grazing, uncertain), and 5.5-5 ka BP in the coniferous-deciduous mixed forest, NE subtropical region, and NW Tibetan Plateau (grazing). Further intensification of anthropogenic land-cover change is indicated 5-4.5 ka BP in the E temperate steppe, and S and NE Tibetan Plateau (grazing, cultivation uncertain), 3.5-3 ka BP in S and NE Tibetan Plateau, W temperate steppe, temperate desert (grazing), and NW Tibetan Plateau (probably grazing), and 2.5-2 ka BP in the temperate deciduous forest, N subtropical region, and temperate desert (grazing). These changes generally agree with increased human activity as documented by archaeological studies. REVEALS reconstructions have a stronger potential than biomization to evaluate scenarios of anthropogenic land-cover change such as HYDE, given they are combined with information from archaeological studies.
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| 5. |
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| 6. |
- Zhao, Dongmei, 1963, et al.
(författare)
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Study of Bed Material Agglomeration in A Horizontal Circulating Fluidized Bed Boiler Burning Rice Husk
- 2012
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Ingår i: Proceedings of the 21:st International Conference on Fluidized Bed Combustion.
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Konferensbidrag (refereegranskat)abstract
- During combustion of potassium containing biomass, there is a risk for bed material agglomeration when using circulating fluidized bed boilers (CFB). Tsinghua University has developed a new type of CFB Boiler, a so called horizontal circulating fluidized bed boiler (HCFBB). Instead of having one high combustion chamber, it consists of three combustion chambers with low height but placed in parallel horizontally. The alkali related bed material agglomeration was studied in one of such boilers in Xiamen, China, burning rice husk. Ash samples from the bottom of the bed, from the bottom of the join part of the secondary and burnout chamber and from the cyclone have been taken and they have been studied by SEM-EDX analysis. The results show some interesting correlation among potassium, aluminum, phosphorus. The collection of deposit on heat exchange tubes in the convection section of the boiler was attempted using a deposit probe situated in the flue gas channel during combustion, however no deposit was formed.
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| 7. |
- Zhao, Qinghai, et al.
(författare)
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Effects of dextranation on the pharmacokinetics of short peptides : A PETstudy on mEGF
- 1999
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 10:6, s. 938-946
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Tidskriftsartikel (refereegranskat)abstract
- The effects of dextranation on the biodistribution of mouse epidermal growth factor (mEGF, 6 kDa) were assessed. By reductive amination, mEGF was coupled to 13 and 46 kDa dextran. The two dextranated conjugates and free mEGF were labeled with the positron-emitting nuclide (76)Br (T(1/2) = 16 h). After intravenous administration to Sprague Dawley rats, the radioactivity biodistribution was evaluated by positron emission tomography (PET) and by measurements of dissected tissues. The dextranation prolonged the retention time in blood, especially when the dextran chain was long. [(76)Br]mEGF-dextran conjugates were shown to have significantly, more than 5 times, lower kidney accumulation than the nonconjugated [(76)Br]mEGF. In conclusion, dextranation affects the biodistribution of mEGF in vivo giving a prolonged circulation time, a decreased uptake in kidney, and an increased spleen accumulation.
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| 8. |
- Zhao, Qinghai
(författare)
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Targeting to EGF receptors : Preparation and experimental analysis of end-end coupled mEGF-dextran conjugates
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Targeted tumor therapy is to deliver cytotoxic agents selectively to tumor cells. By such delivery, normal tissues receive minimal damage while a therapeutical effect is achieved in tumor. A targetingsystem can be constructed by conjugating a tumor-seeking molecule and toxic agents via a carrier. In this thesis, mouse epidermal growth factor, mEGF, was the tumor-seeking molecule for targeting against malignancies that overexpress EGF receptors. Dextran was attached to mEGF by different methods and used as a carrier. Preparation of different mEGF-dextran conjugates, effects of different conjugation methods on cellular intenalization and the biodistribution of the conjugates in vivo were studied in the planning for future clinic trials.Two end-end coupling methods have been developed in this thesis. One is direct reductive amination by which the terminal amino group of mEGF reacts with the aldehyde group on rhe reducting end of dextran. The other end-end coupling methods is glutaraldehyde mediated cross-linking, in which a few glutaraldehyde molecules act as a linker between the amino terminus of mEGF and the end-aminated dextran.The end-end coupled mEGF-dextran conjugates were investigated together with a randomly coupled mEGF-dextran conjugate, for cellular binding ptterns using cultured glioma cells. The time for maximal binding and the intracellular retention of the conjugates were analysed. The intracellular radioactivity associated with free mEGF had a fast turnover whereas all three conjugates gave long half-lives for the intracellular retention.The end-end coupled mEGF-dextran, type A prepared by reductive amination, had a dissociation constant of 7.1 x 10-9 M and free mEGF had a value of 6.6 x 10-10 M. The end-end coupled intermediate was further activated by the cyanopyridinium agent CDAP and tyrosines were introduced to the dextran part of the conjugate. The iodinated conjugate could to a large extent be internalized in test cells and the radioactivity was retained intracellularly better than when the radioactivity only was on the mEGF part of the conjugate.Dextranated mEGF had a slower clearance in blood and liver than mEGF as seen in positron emission tomography on rats. Dextranated mEGF also had a lower uptake in kidney than free mEGF. There was an "unknown mEGF complex" in the blood circulation which was formed after mEGF was injected but this complex did not appear in urine samples.
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