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1.
本文研究了Cu(Ⅱ)-PEG(聚乙二醇-2000)-Zincon(锌试剂)-(NH4)2SO4体系的析相光度法并应用于测定Cu(Ⅱ)。最宜酸度为pH5.5~8.5(KH2PO4-K2HPO4)缓冲溶液)其络合物的最大吸收位于610nm,表观摩尔吸光系数为4.0×10^4L.mol^-1.cm^-1,Cu(Ⅱ)浓度在0~1.5mg/L范围内服从比尔定律,铜与Zincon形式组成为1:2的稳定的蓝色络  相似文献   

2.
通过缺位填充法合成了分子式为α2-K7P2W17O61(La· OH2)的镧(Ⅲ)取代十八钨磷酸盐。在玻碳电极(GC)上,用电化学方法将单取代Dawson型杂多酸盐α2-K7P2W17O61(La·OH2)的阴离子(P2W17La)掺杂到聚吡咯(PPY)薄膜中制成P2W17La/PPY/GC化学修饰电极,既保持该杂多酸的电化学活性和电催化性能,又具有良好的稳定性和灵敏度。研究表明, 0. 50 mol/L HCI溶液中,聚吡咯薄膜中 P2W17La的第一对氧化还原峰对 NO2的电还原具有良好的催化活性,其催化电流与 NO2浓度在 6.0 × 10-5- 1.0 × 10-2mol/L范围内呈线性关系。  相似文献   

3.
研究了脱氧核糖核酸的极谱伏安行为,在0.1mol.L^-1NH4Cl溶液中DNA产生一良好的极谱峰,峰电位Ep=-1.65V(vs.Ag/AgCl),且峰电流ip与DNA的浓度在4.5*10^-5-3.7*10^-4mol.LO^-1范围内呈线性关系,可望用于DNA的定量分析。  相似文献   

4.
研究了细胞色素C(Cyt.C)在一种新的电子转移促进剂4,6-二甲基-2-巯基嘧啶修饰微带金电极(DMMP/Au)上的氧化还原热力学;求得Cyt.C在DMMP/Au电极上反应的标准电极电位E^o,熵变△S^o,焓变△II^o及Gibbs自由能的改变△G10值分别为:0.272V(us.NHE),-123.7J.mol^-^1,-63.1kJ.mol.mol^-^1和-26.2kJ.mol^-^1(  相似文献   

5.
Ce3+对大白鼠和豚鼠心肌的影响   总被引:6,自引:0,他引:6  
研究了Ce^3+对离体豚鼠心房收缩,离体豚鼠乳头肌及在体大白鼠心肌动作电位的影响。浓度为0.05mmol.L^-1的Ce^3+溶液可抑制豚鼠右心房的自律性和左心房的收缩。0.1和0.2mmol.L^-1Ce^3+溶液对豚鼠乳头肌动作电位时程影响不显著。  相似文献   

6.
侧脑室注射氯化镧对大鼠血清生长素和甲状腺素的影响   总被引:3,自引:0,他引:3  
西方研究了侧脑室注入LaCl3对大鼠血清中生长系,甲状腺素,促甲状腺素和下丘脑中生长抑素的影响。侧脑室注射0.001和0.01mol.l^-1LaCl3,血清中T4和GH含量明显高于对照组,0.1和0.5mol.l^-1LaCl3组血清T4和GH未见明显变化。  相似文献   

7.
提出了在乙酸钠-乙酸介质中,利用Al-EGTA-PR-CPB四元体系测定铝的新方法。试验表明乙二醇二乙醚二氨基四乙酸(EGTA),铝,邻苯三酚红(PR),溴化十六烷基吡啶(CPB)可迅速反应生成四元蓝色配合物Al·EGTA·PR3·CPB12,可用于痕量铝的测定,ε=1.1×10^5L·mol^-1·cm^-1,RSD为5.8%(n=6)。加标回收率101.7% ̄105.0%,实测水和化学试剂中痕  相似文献   

8.
丁基罗丹明B—钼酸盐光度法连续测定铈和钪   总被引:4,自引:0,他引:4  
王加林  徐其亨 《分析化学》1996,24(3):344-347
在聚乙烯醇(PVA)存在下,丁基罗丹明B(BRB)分别与铈钼、钪钼杂多酸络阴离子形成离子缔合物,其最大吸收均位于570nm,表面摩尔吸光度分别为εCe=3.96×10^6L.mol^-1.cm^-1,εSc=4.71×10^5L.mol^-1.cm^-1,服从比耳定律范围分别为0-24μg/L Ce和0-60μg/LSc,测定极限为Ce1.0μg/L(n=12)和Sc1.9μg/L(n=10),对  相似文献   

9.
用HPLC/ECD法测定血小板5-HT,运用 WatersμBondapak C柱,3,4二羟基苄胺(DH-BA)作内标,以 0.07 mol/L乙酸钠缓冲液+乙腈为流动相(20+1),每1L缓冲液含 0.05 mol/L柠檬酸、2.5 mmol/L庚烷磺酸钠、0.1mmol/L Na_2EDTA,流速0.8 mL/min。DHBA和 5-HT的保留时间分别为5.4和11.5 min,线性范围为0.025~1mg/L(r= 0.9997)。5-HT日内 RSD低于1.87%,日间RSD低于8.54%,方法回收率为100.4%±2.3%。提示本方法快速简便,灵敏准确,适用于临床基础研究。  相似文献   

10.
铜(Ⅱ)和锌(Ⅱ)分别在0.1mol/LKH2PO4-Na2HPO4缓冲溶液(pH6.5)和0.25mol/LNH4Cl溶液中,与氟哌酸形成良好的络合吸附波,峰电位分别为-0.26V和-1.28V(vs.SCE),络合比分别为1:3和1:2,峰电流与铜(Ⅱ)和锌(Ⅱ)的浓度均在4.0×10^-7~5.0×10^-6nol/L范围内呈线性关系,检测限分别为7.0×10^-8和5.0×10^-8mol  相似文献   

11.
Secretome of multipotent mesenchymal stromal cells (MSCs) is actively used in biomedical applications such as alveolar bone regeneration, treatment of cardiovascular disease, and neurodegenerative disorders. Nevertheless, hMSCs have low proliferative potential and production of the industrial quantity of their secretome might be challenging. Human fetal multipotent mesenchymal stromal cells (FetMSCs) isolated from early human embryo bone marrow are easy to expand and might be a potential source for pharmaceutical substances production based on their secretome. However, the secretome of FetMSCs was not previously analyzed. Here, we describe the secretome of FetMSCs using LC-MALDI shotgun proteomics. We identified 236 proteins. Functional annotation of the identified proteins revealed their involvement in angiogenesis, ossification, regulation of apoptosis, and immune response processes, which made it promising for biomedical applications. The proteins identified in the FetMSCs secretome are involved in the same biological processes as proteins from previously described adult hMSCs secretomes. Nevertheless, many of the common hMSCs secretome components (such as VEGF, FGF, Wnt and TGF-β) have not been identified in the FetMSCs secretome.  相似文献   

12.
13.
Only two nucleic acid directed chemical reactions that are compatible with live cells have been reported to date. Neither of these processes generate toxic species from nontoxic starting materials. Reactions of the latter type could be applied as gene‐specific drugs, for example, in the treatment of cancer. We report here the first example of a chemical reaction that generates a cytotoxic drug from a nontoxic prodrug in the presence of a specific endogeneous ribonucleic acid in live mammalian cells. In this case, the prodrug is triplet oxygen and the drug is singlet oxygen. The key component of this reaction is an inert molecule (InP–2′‐OMe‐RNA/Q–2′‐OMe‐RNA; P: photosensitizer; Q: quencher), which becomes an active photosensitizer (InP–2′‐OMe‐RNA) in the presence of single‐stranded nucleic acid targets. Upon irradiation with red light, the photosensitizer produces over 6000 equivalents of toxic singlet oxygen per nucleic acid target. This reaction is highly sequence specific. To detect the generation of singlet oxygen in live cells, we prepared a membrane‐permeable and water‐soluble fluorescent scavenger, a derivative of 2,5‐diphenylisobenzofurane. The scavenger decomposes upon reaction with singlet oxygen and this is manifested in a decrease in the fluorescence intensity. This effect can be conveniently monitored by flow cytometry.  相似文献   

14.
Recent observations indicate that the resistance of apoptosis is an important process of tumor metastasis and metastases are the cause of 90% of human cancer death. Etoposide, a semisynthetic derivative of the podophyllotoxins, is a clinically used anti-cancer reagent, but the effects of it on metastatic gastric carcinoma cells are totally unknown. In this study, etoposide induced apoptotic cell death in human gastric adenocarcinoma cell line SGC-7901, derived from metastatic lymph nodes, as evidenced by the analysis of DNA fragmentation, apoptotic body formation, caspase activation, and apoptosis specific changes in cell morphology is demonstrated. The depolarization of mitochondrial membrane and the release of cytochrome c were most early events in etoposide treated SGC-7901 cells, and were followed by caspase-3 activation and PARP cleavage. Caspase-8 activation was not detected under the same condition. Thus, it was proposed that etoposide induces caspase-associated apoptotic cell death in human metastatic gastric carcinoma, which is initiated by mitochondrial cytochrome c release.  相似文献   

15.
Human ECFCs contribute to vascular repair. For this reason, they are considered as valuable cell therapy products in ischemic diseases. Porous scaffolds are prepared that are composed of natural polysaccharides, pullulan and dextran, by chemical crosslinking without use of organic solvents. These porous scaffolds, which have pores with an average size of 42 µm and a porosity of 21%, preserve the viability and the proliferation of cord‐blood ECFCs. After 7 d of culture in porous scaffolds, ECFCs express endothelial markers (CD31 and vWf) and maintain endothelial functions. The cultured cells can be easily retrieved by enzymatic degradation of the porous scaffolds. In vitro results suggest that the porous scaffold could allow cell delivery of ECFCs for treatment of vascular diseases.

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16.
17.
The effect of substrate‐mediated signals on osteogenic differentiation of hMSCs is studied using a synthetic bone‐like material comprising both organic and inorganic components that supports adhesion, spreading, and proliferation of hMSCs. hMSCs undergo osteogenic differentiation even in the absence of osteogenesis‐inducing supplements. They exhibit higher expressions of Runx2, BSP, and OCN compared to their matrix‐rigidity‐matched, non‐mineralized hydrogel counterparts. The mineralized‐hydrogel‐assisted osteogenic differentiation of hMSCs could be attributed to their exposure to high local concentrations of calcium and phosphate ions in conjunction with chemical and topological cues arising from the hydrogel‐bound calcium phosphate mineral layer.

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18.
19.
Electrical stimulation (ES) within a conductive scaffold is potentially beneficial in encouraging the differentiation of stem cells toward a neuronal phenotype. To improve stem cell-based regenerative therapies, it is essential to use electroconductive scaffolds with appropriate stiffnesses to regulate the amount and location of ES delivery. Herein, biodegradable electroconductive substrates with different stiffnesses are fabricated from chitosan-grafted-polyaniline (CS-g-PANI) copolymers. Human mesenchymal stem cells (hMSCs) cultured on soft conductive scaffolds show a morphological change with significant filopodial elongation after electrically stimulated culture along with upregulation of neuronal markers and downregulation of glial markers. Compared to stiff conductive scaffolds and non-conductive CS scaffolds, soft conductive CS-g-PANI scaffolds promote increased expression of microtubule-associated protein 2 (MAP2) and neurofilament heavy chain (NF-H) after application of ES. At the same time, there is a decrease in the expression of the glial markers glial fibrillary acidic protein (GFAP) and vimentin after ES. Furthermore, the elevation of intracellular calcium [Ca2+] during spontaneous, cell-generated Ca2+ transients further suggests that electric field stimulation of hMSCs cultured on conductive substrates can promote a neural-like phenotype. The findings suggest that the combination of the soft conductive CS-g-PANI substrate and ES is a promising new tool for enhancing neuronal tissue engineering outcomes.  相似文献   

20.
In this study the redox activity of human myocardium‐derived mesenchymal stem cells (hmMSC) were investigated by redox‐competition (RC‐SECM) and generation‐collection (GC‐SECM) modes of scanning electrochemical microscopy (SECM), using 2‐methylnaphthalene‐1,4‐dione (menadione, MD) as a redox mediator. The redox activity of human healthy and dilated hmMSCs was evaluated by measuring reduction of MD. Measurements were performed by approaching and retracting the UME from the surface of growing hmMSC cells. The current study shows that the RC‐SECM mode can be applied to investigate integrity of cell membranes, whereas the most promising results were observed by using the GC‐SECM mode and applying the Hill's equation for the calculation/fitting of dependencies of electrical current vs menadione concentration. The calculated apparent Michaelis constant (KM) for the production of menadiol (MDH2) in the pathological hmMSC cells was 14.4 folds higher compared to that of the healthy hmMSC revealing the lover redox activity of pathological cells. Moreover, the calculated Hill's coefficient n shows a negative cooperative binding between MD and healthy hmMSC and positive cooperative binding between MD and pathological hmMSC. It means that healthy hmMSC is of lower affinity to MD, which is also related to the better membrane integrity of healthy cells. Data of this study demonstrate that SECM can be applied to investigate intracellular redox and membrane changes ongoing in human dilated myocardium‐derived hmMSC in order to improve their functioning and further regenerative potential.  相似文献   

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