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31.
Jun Zhao Shaoyi Wang Jianqiang Bao Xiaojuan Sun Xiaochen Zhang Xiuli Zhang Dongxia Ye Jie Wei Changsheng Liu Xinquan Jiang Gang Shen Zhiyuan Zhang 《PloS one》2013,8(1)
Calcium phosphate (Ca-P) scaffolds have been widely employed as a supportive matrix and delivery system for bone tissue engineering. Previous studies using osteoinductive growth factors loaded Ca-P scaffolds via passive adsorption often experience issues associated with easy inactivation and uncontrolled release. In present study, a new delivery system was fabricated using bone morphogenetic protein-2 (BMP-2) loaded calcium-deficient hydroxyapatite (CDHA) scaffold by lyophilization with addition of trehalose. The in vitro osteogenesis effects of this formulation were compared with lyophilized BMP-2/CDHA construct without trehalose and absorbed BMP-2/CDHA constructs with or without trehalose. The release characteristics and alkaline phosphatase (ALP) activity analyses showed that addition of trehalose could sufficiently protect BMP-2 bioactivity during lyophilization and achieve sustained BMP-2 release from lyophilized CDHA construct in vitro and in vivo. However, absorbed BMP-2/CDHA constructs with or without trehalose showed similar BMP-2 bioactivity and presented a burst release. Quantitative real-time PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) demonstrated that lyophilized BMP-2/CDHA construct with trehalose (lyo-tre-BMP-2) promoted osteogenic differentiation of bone marrow stromal cells (bMSCs) significantly and this formulation could preserve over 70% protein bioactivity after 5 weeks storage at 25°C. Micro-computed tomography, histological and fluorescent labeling analyses further demonstrated that lyo-tre-BMP-2 formulation combined with bMSCs led to the most percentage of new bone volume (38.79% ±5.32%) and area (40.71% ±7.14%) as well as the most percentage of fluorochrome stained bone area (alizarin red S: 2.64% ±0.44%, calcein: 6.08% ±1.37%) and mineral apposition rate (4.13±0.62 µm/day) in critical-sized rat cranial defects healing. Biomechanical tests also indicated the maximum stiffness (118.17±15.02 Mpa) and load of fracture (144.67±16.13 N). These results lay a potential framework for future study by using trehalose to preserve growth factor bioactivity and optimize release profile of Ca-P based delivery system for enhanced bone regeneration. 相似文献
32.
Baoquan Bao Hung The Dang Ping Zhang Jongki Hong Chong-O. Lee Hee Young Cho Jee H. Jung 《Bioorganic & medicinal chemistry letters》2009,19(21):6205-6208
In the course of our search for bioactive metabolites from a colonial tunicate of the family Polyclinidae, six new (1–6) cyclic fatty acid derivatives were isolated. Their planar structures were established on the basis of NMR and MS spectroscopic analyses. The relative configuration was determined by NOESY experiment. Compounds 1–6 represent a fused bicyclic skeleton possibly derived from α,ω-dicarboxylic acids such as eicosanedioic acid or docosanedioic acid via a Diels–Alder type of cyclization. Compounds 1–4 and 6 showed mild cytotoxicity against a panel of five human solid tumor cell lines. 相似文献
33.
高温强光胁迫对苹果果皮PPO活性的影响 总被引:3,自引:0,他引:3
苹果果实日烧是一种普遍发生的生理病害,最常见的特征之一就是在果实表面出现褐变。通常认为PPO与植物的酶促褐变密切相关。研究了自然和控制条件下,高温强光胁迫对果实PPO活性的影响,以便揭示高温强光胁迫下苹果果实褐变与PPO活性之间的联系。结果表明:高温和强光胁迫与果皮PPO活性变化密切相关。就树冠不同方位而言,西南方位是高温和强光胁迫最严重的区域,其外围裸露果实的PPO活性也最强。在一定范围内,随着处理温度和光照强度的升高,果皮PPO活性也逐渐增强。短时间剧烈升温能够引起PPO活性骤然上升。在同样程度的高温胁迫下,提高环境湿度有利于抑制果皮PPO活性,从而减轻褐变症状的发生。室内外试验一致证实:果实日烧褐变现象与高温强光胁迫下果皮组织PPO活性大幅度提高有直接关系。 相似文献
34.
Silicon-mediated alleviation of Mn toxicity in Cucumis sativus in relation to activities of superoxide dismutase and ascorbate peroxidase 总被引:14,自引:0,他引:14
The effects of exogenous silicon (Si) on plant growth, activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR) and catalase, and concentrations of ascorbate and glutathione were investigated in cucumber (Cucumis sativus L.) plants treated with excess manganese (Mn) (600 microM). Compared with the treatment of normal Mn (10 microM), excess Mn significantly increased H2O2 concentration and lipid peroxidation indicated by accumulation of thiobarbituric acid reactive substances. The leaves showed apparent symptoms of Mn toxicity and the plant growth was significantly inhibited by excess Mn. The addition of Si significantly decreased lipid peroxidation caused by excess Mn, inhibited the appearance of Mn toxicity symptoms, and improved plant growth. This alleviation of Mn toxicity by Si was related to a significant increase in the activities of SOD, APX, DHAR and GR and the concentrations of ascorbate and glutathione. 相似文献
35.
Shijia Luo Yanhong He Guogui Ning Jiaqi Zhang Guangying Ma Manzhu Bao 《Trees - Structure and Function》2011,25(6):1063-1071
Dove tree (Davidia involucrate) is a Tertiary relic species endemic to China and is reputed to be a ‘living fossil’ in the plant kingdom. Genetic diversity
and genetic structure of this species were analyzed for its conservation and management, using inter-simple sequence repeat
(ISSR) data obtained from eight populations distributed throughout seven provinces of China. A relatively high level of genetic
diversity, at both population and species levels, was detected using the POPGENE software. Analysis of molecular variance
(AMOVA) revealed a moderate level of among-population variation (i.e., 33.21%). The genetic structure of dove tree was closely
consistent with their isolated topographical distribution region based on the results of the STRUCTURE, POPGENE-UPGMA and
PCA analysis. It is postulated that the relatively high level of genetic diversity has been maintained because of: (a) the
original wild geographical distribution, (b) propagation through outcrossing seeds or root suckers, (c) the longevity of individuals
and (d) the relatively little human disturbance. Genetic drift and restricted gene are important factors affecting genetic
differentiation. There was no significant correlation between geographical distances and a pairwise comparison with genetic
distances, as analyzed by the Mantel test, but the clustering result of genetic diversity was consistent with their isolated
topographical distribution regions. Thus, maintaining the stable special habitats associated with this species is recommended
for the in situ conservation. Furthermore, it is important to develop an effective seed germination system for the maintenance
of an ex situ conservation pool of the germplasm resources. 相似文献
36.
A Practicable Li/Na‐Ion Hybrid Full Battery Assembled by a High‐Voltage Cathode and Commercial Graphite Anode: Superior Energy Storage Performance and Working Mechanism 下载免费PDF全文
Jin‐Zhi Guo Yang Yang Dao‐Sheng Liu Xing‐Long Wu Bao‐Hua Hou Wei‐Lin Pang Ke‐Cheng Huang Jing‐Ping Zhang Zhong‐Min Su 《Liver Transplantation》2018,8(10)
With the rapidly growing demand for low‐cost and safe energy storage, the advanced battery concepts have triggered strong interests beyond the state‐of‐the‐art Li‐ion batteries (LIBs). Herein, a novel hybrid Li/Na‐ion full battery (HLNIB) composed of the high‐energy and lithium‐free Na3V2(PO4)2O2F (NVPOF) cathode and commercial graphite anode mesophase carbon micro beads is for the first time designed. The assembled HLNIBs exhibit two high working voltage at about 4.05 and 3.69 V with a specific capacity of 112.7 mA h g?1. Its energy density can reach up to 328 W h kg?1 calculated from the total mass of both cathode and anode materials. Moreover, the HLNIBs show outstanding high‐rate capability, long‐term cycle life, and excellent low‐temperature performance. In addition, the reaction kinetics and Li/Na‐insertion/extraction mechanism into/out NVPOF is preliminarily investigated by the galvanostatic intermittent titration technique and ex situ X‐ray diffraction. This work provides a new and profound direction to develop advanced hybrid batteries. 相似文献
37.
38.
Devi YS Seibold AM Shehu A Maizels E Halperin J Le J Binart N Bao L Gibori G 《The Journal of biological chemistry》2011,286(9):7609-7618
Prolactin (PRL) is essential for normal reproduction and signals through two types of receptors, the short (PRL-RS) and long (PRL-RL) form. We have previously shown that transgenic mice expressing only PRL-RS (PRLR(-/-)RS) display abnormal follicular development and premature ovarian failure. Here, we report that MAPK, essential for normal follicular development, is critically inhibited by PRL in reproductive tissues of PRLR(-/-)RS mice. Consequently, the phosphorylation of MAPK downstream targets are also markedly inhibited by PRL without affecting immediate upstream kinases, suggesting involvement of MAPK specific phosphatase(s) in this inhibition. Similar results are obtained in a PRL-responsive ovary-derived cell line (GG-CL) that expresses only PRL-RS. However, we found the expression/activation of several known MAPK phosphatases not to be affected by PRL, suggesting a role of unidentified phosphatase(s). We detected a 27-kDa protein that binds to the intracellular domain of PRL-RS and identified it as dual specific phosphatase DUPD1. PRL does not induce expression of DUDP1 but represses its phosphorylation on Thr-155. We also show a physical association of this phosphatase with ERK1/2 and p38 MAPK. Using an in vitro phosphatase assay and overexpression studies, we established that DUPD1 is a MAPK phosphatase. Dual specific phosphatase inhibitors as well as siRNA to DUPD1, completely prevent PRL-mediated MAPK inhibition in ovarian cells. Our results strongly suggest that deactivation of MAPK by PRL/PRL-RS contributes to the severe ovarian defect in PRLR(-/-)RS mice and demonstrate the novel association of PRL-RS with DUPD1 and a role for this phosphatase in MAPK deactivation. 相似文献
39.
Threonine phosphorylation diverts internalized epidermal growth factor receptors from a degradative pathway to the recycling endosome 总被引:12,自引:0,他引:12
Bao J Alroy I Waterman H Schejter ED Brodie C Gruenberg J Yarden Y 《The Journal of biological chemistry》2000,275(34):26178-26186
Transregulation of the epidermal growth factor receptor (EGFR) by protein kinase C (PKC) serves as a model for heterologous desensitization of receptor tyrosine kinases, but the underlying mechanism remained unknown. By using c-Cbl-induced ubiquitination of EGFR as a marker for transfer from early to late endosomes, we provide evidence that PKC can inhibit this process. In parallel, receptor down-regulation and degradation are significantly reduced. The inhibitory effects of PKC are mediated by a single threonine residue (threonine 654) of EGFR, which serves as a major PKC phosphorylation site. Biochemical and morphological analyses indicate that threonine-phosphorylated EGFR molecules undergo normal internalization, but instead of sorting to lysosomal degradation, they recycle back to the cell surface. In conclusion, by sorting EGFR to the recycling endosome, heterologous desensitization restrains ligand-induced down-regulation of EGFR. 相似文献
40.
Christopher M. Harris Anna M. Ericsson Maria A. Argiriadi Claude Barberis David W. Borhani Andrew Burchat David J. Calderwood George A. Cunha Richard W. Dixon Kristine E. Frank Eric F. Johnson Joanne Kamens Silvia Kwak Biqin Li Kelly D. Mullen Denise C. Perron Lu Wang Neil Wishart Xiaoyun Wu Xiaolei Zhang Robert V. Talanian 《Bioorganic & medicinal chemistry letters》2010,20(1):334-337
We describe structure-based optimization of a series of novel 2,4-diaminopyrimidine MK2 inhibitors. Co-crystal structures (see accompanying Letter) demonstrated a unique inhibitor binding mode. Resulting inhibitors had IC50 values as low as 19 nM and moderate selectivity against a kinase panel. Compounds 15, 31a, and 31b inhibit TNFα production in peripheral human monocytes. 相似文献