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81.
目的:制备了壳聚糖Zn2+固定化亲和层析填料,并对其性能进行了研究。方法:采用反相悬浮法制备了交联壳聚糖;再以环氧氯丙烷为活化剂,乙二胺为螯合配基,制备了固定化亲和层析填料;表征了其有效粒径以及均匀系数、含水量、失重率、氨基含量、骨架密度、堆积密度以及孔度值。从时间、加入ZnCl2的浓度、温度、pH方面对Zn2+固定化条件进行了优选,并确定了Zn2+的固定化量。含组氨酸标签的乙醛脱氢酶粗酶液,经硫酸铵盐析后,考察了壳聚糖Zn2+固定化亲和层析填料的亲和性能。结果:制备的填料有效粒径为105μm;均匀系数为1.46;含水量为58.03%;失重率为85.43%;氨基含量为9.20mmol/g;骨架密度为1.217 8g/ml;堆积密度为0.843 2g/ml;孔度值为36.40%。固定化Zn2+的最佳条件是:时间3 h、加入ZnCl2溶液浓度0.1mol/L、温度28℃、pH 5.5;且此条件下,亲和层析填料中Zn2+固定化量为3.35mmol/g。壳聚糖Zn2+固定化亲和层析填料对乙醛脱氢酶的亲和性能为4.14IU/g(干重)。结论:制备了壳聚糖Zn2+固定化亲和层析填料,可用于带有组氨酸标签重组蛋白的快速分离与纯化。  相似文献   
82.
ABSTRACT

This study investigated the repair process and enzymatic activity responses after induction of shell regeneration in Pomacea canaliculata. The survival rates, height of regenerated shell, and activities of alkaline phosphatase (ALP) and carbonic anhydrase (CA) were investigated and recorded for 15 days. A triangular piece of shell about 8?mm wide was excised from the ventral region of the shell. On the basis of photographs and enzyme assay, it was concluded both yellow-shell apple snails and black-shell apple snails had high survival rates (100%). The regenerated new shell was initially thin, with the wound sealed 5 days after induction of shell regeneration; after that the regenerated shell thickened. Three snails were sampled at 0, 0.5, 1, 2, 3, 5, 10 and 15 days after shell excision for analysis of enzymatic activity of ALP and CA. Trends of the activity of ALP and CA in the mantle were similar. Initially they both showed a decline on the first day, then rose on following days. Activity of ALP declined to a minimum on the first day, and an activity peak in both colour forms appeared on the fifth day (P?<?0.05) and was maintained for the rest of the experiment. The minimum value of CA occurred after 0.5 days, and a significant increase was also observed on the fifth day (P?<?0.05). This study has revealed that apple snails have good shell regeneration abilities, and that ALP and CA probably play a crucial role in shell growth and regeneration.  相似文献   
83.
Tyrosinase could oxidize tyrosyl residues in silk fibroin and result in the production of activated o‐quinone residues, which could facilitate the grafting of the functional amino‐compounds onto silk fibers. In this study, the enzymatic modifications of Bombyx mori silk fibroin with tyrosinase and chitosan were investigated, aiming at improving the properties of silk fabrics, including dyeability, crinkling resistance, and antibacterial activity. The grafting grades of chitosan were evaluated by a color‐development method using bromocresol green. The result indicated that chitosan molecules were not only adsorbed on silk fibers via electrostatic interactions, they also could react with the oxidized silk fibers with tyrosinase. For the silk fabric combinedly treated with tyrosinase and chitosan, tensile strength and crinkling resistance were noticeably increased as compared to that of the chitosan‐treated. The antibacterial activity and its durability measurements revealed the actions of the tyrosinase‐catalyzed grafting of chitosan. The efficacy of the graft reaction might be further enhanced by increasing the accessibility of reactive sites in silk fibers.  相似文献   
84.
85.
功能性高分子材料壳聚糖(CS)及其复合其他材料作为组织工程的支架材料已在生物医学领域等方面取得了一定的进展。CS自身的功能基团可聚合一些聚合物来增强其复合支架的各方面性能,从而使其应用范围更广泛,应用效率更高。在神经损伤中,CS支架材料对促进神经的再生和修复起着至关重要的作用,主要对CS在神经组织工程方面的应用研究做了简要概述。  相似文献   
86.
BACKGROUNDImpaired wound healing can be associated with different pathological states. Burn wounds are the most common and detrimental injuries and remain a major health issue worldwide. Mesenchymal stem cells (MSCs) possess the ability to regenerate tissues by secreting factors involved in promoting cell migration, proliferation and differentiation, while suppressing immune reactions. Preconditioning of MSCs with small molecules having cytoprotective properties can enhance the potential of these cells for their use in cell-based therapeutics.AIMTo enhance the therapeutic potential of MSCs by preconditioning them with isorhamnetin for second degree burn wounds in rats.METHODSHuman umbilical cord MSCs (hU-MSCs) were isolated and characterized by surface markers, CD105, vimentin and CD90. For preconditioning, hU-MSCs were treated with isorhamnetin after selection of the optimized concentration (5 µmol/L) by cytotoxicity analysis. The migration potential of these MSCs was analyzed by the in vitro scratch assay. The healing potential of normal, and preconditioned hU-MSCs was compared by transplanting these MSCs in a rat model of a second degree burn wound. Normal, and preconditioned MSCs (IH + MSCs) were transplanted after 72 h of burn injury and observed for 2 wk. Histological and gene expression analyses were performed on day 7 and 14 after cell transplantation to determine complete wound healing.RESULTSThe scratch assay analysis showed a significant reduction in the scratch area in the case of IH + MSCs compared to the normal untreated MSCs at 24 h, while complete closure of the scratch area was observed at 48 h. Histological analysis showed reduced inflammation, completely remodeled epidermis and dermis without scar formation and regeneration of hair follicles in the group that received IH + MSCs. Gene expression analysis was time dependent and more pronounced in the case of IH + MSCs. Interleukin (IL)-1β, IL-6 and Bcl-2 associated X genes showed significant downregulation, while transforming growth factor β, vascular endothelial growth factor, Bcl-2 and matrix metallopeptidase 9 showed significant upregulation compared to the burn wound, showing increased angiogenesis and reduced inflammation and apoptosis.CONCLUSIONPreconditioning of hU-MSCs with isorhamnetin decreases wound progression by reducing inflammation, and improving tissue architecture and wound healing. The study outcome is expected to lead to an improved cell-based therapeutic approach for burn wounds.  相似文献   
87.
宋超  牛翠娟  陈欣然 《动物学报》2007,53(2):270-277
本研究旨在探讨壳聚糖对急性氨氮胁迫下中华鳖(Pelodiscus sinensis)稚鳖非特异性免疫功能的影响。实验共设5组,实验组中华鳖分别腹腔注射0mg/ml(C0组)、1mg/ml(C1组)、5mg/ml(C2组)、50mg/ml(C3组)壳聚糖溶液0.1ml,并饲养于总氨氮浓度(TAN)为110mg/L的水环境中;对照组注射等量生理盐水溶液并饲养于新鲜晾晒自来水中。注射7d后观测外周血和脾脏中淋巴细胞ANAE阳性率、血清旁路途径溶血活性、血清溶菌活性。与对照组相比,C0组外周血T淋巴细胞ANAE阳性率和血清旁路途径溶血活性均有显著提高,脾脏T淋巴细胞和血清溶菌活性没有显著变化。与C0组相比,注射壳聚糖各组外周血T淋巴细胞ANAE阳性率和血清溶血活性均有不同程度的显著下降,并且恢复到接近对照组的水平(P>0.05),只有C3组溶血活性显著低于对照组;注射壳聚糖对脾脏中T淋巴细胞ANAE活性没有显著影响。C2组溶菌活性显著高于其他组,其他各组间差异不显著。表明壳聚糖对氨氮胁迫导致的免疫应激反应有一定的拮抗作用,其作用强度因壳聚糖浓度和免疫指标不同而异  相似文献   
88.
Wounding of trees by debarking during the vegetative period sometimes results in the formation of callus tissue which develops over the entire wound surface or on parts of it. This light and transmission electron microscopy study of living lime trees found that the formation of such a surface callus is subdivided into three stages. During the first stage, numerous cell divisions take place in regions where differentiating xylem remains at the wound surface after debarking. This young callus tissue consists of isodiametric parenchymatous cells. Cambium cells, sometimes also remaining at the wound surface, collapse and do not contribute to callus formation. During the second stage, cells in the callus undergo differentiation by forming a wound periderm with phellem, phellogen and phelloderm. In the third stage, a cambial zone develops between the wound periderm and the xylem tissue laid down prior to wounding. This process is initiated by anticlinal and periclinal divisions of a few callus cells only. Later this process extends tangentially to form a continuous belt of wound cambium. Subsequently, this cambium produces both wound xylem and wound phloem and thus contributes to further thickening.  相似文献   
89.
WKYMVm hexapeptide has been identified as a strong FPR2 agonist through a library screening of synthetic peptides. The FPR2 has been reported to play a crucial role in inflammation and angiogenic responses via stimulation of chemotaxis, migration, cell proliferation, wound healing and vessel growth. Recently, the therapeutic effects of WKYMVm have been reported in various disease models. In cutaneous wound model in diabetic mice, WKYMVm facilitated wound healing processes by stimulating the formation of capillary and arteriole and re-epithelialization. In coronary artery stenosis model, WKYMVm coating on stent promoted re-endothelialization and lowered restenosis rate. In hindlimb ischemia mouse model, intramuscular injection of WKYMVm promoted homing of exogenously transplanted endothelial colony-forming cells and neovascularization, resulting in salvaging hindlimb. Furthermore, a single injection of WKYMVm encapsulated in poly (lactide-co-glycolide) microspheres was demonstrated to be as efficient as multiple injections of WKYMVm in restoring blood flow in hindlimb ischemia model. These observations may open up promising biomedical applications of WKYMVm for tissue repairs and regenerations.  相似文献   
90.
Despite the wide range of available antibiotics, food borne bacteria demonstrate a huge spectrum of resistance. The current study aims to use natural components such as essential oils (EOs), chitosan, and nano-chitosan that have very influential antibacterial properties with novel technologies like chitosan solution/film loaded with EOs against multi-drug resistant bacteria. Two strains of Escherichia coli O157:H7 and three strains of Listeria monocytogenes were used to estimate antibiotics resistance. Ten EOs and their mixture, chitosan, nano-chitosan, chitosan plus EO solutions, and biodegradable chitosan film enriched with EOs were tested as antibacterial agents against pathogenic bacterial strains. Results showed that E. coli O157:H7 51,659 and L. monocytogenes 19,116 relatively exhibited considerable resistance to more than one single antibiotic. Turmeric, cumin, pepper black, and marjoram did not show any inhibition zone against L. monocytogenes; Whereas, clove, thyme, cinnamon, and garlic EOs exhibited high antibacterial activity against L. monocytogenes with minimum inhibitory concentration (MIC) of 250–400 μl 100?1 ml and against E. coli O157:H7 with an MIC of 350–500 μl 100?1 ml, respectively. Among combinations, clove, and thyme EOs showed the highest antibacterial activity against E. coli O157:H7 with MIC of 170 μl 100?1 ml, and the combination of cinnamon and clove EOs showed the strongest antibacterial activity against L. monocytogenes with an MIC of 120 μl 100?1 ml. Both chitosan and nano-chitosan showed a promising potential as an antibacterial agent against pathogenic bacteria as their MICs were relatively lower against L. monocytogenes than for E. coli O157:H7. Chitosan combined with each of cinnamon, clove, and thyme oil have a more effective antibacterial activity against L. monocytogenes and E. coli O157:H7 than the mixture of oils alone. Furthermore, the use of either chitosan solution or biodegradable chitosan film loaded with a combination of clove and thyme EOs had the strongest antibacterial activity against L. monocytogenes and E. coli O157:H7. However, chitosan film without EOs did not exhibit an inhibition zone against the tested bacterial strains.  相似文献   
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