Species Variation in the Mechanisms of Mesenchymal Stem Cell-Mediated Immunosuppression

Bone marrow-derived mesenchymal stem cells (MSCs) hold great promise for treating immune disorders because of their immunoregulatory capacity, but the mechanism remains controversial. As we show here, the mechanism of MSC-mediated immunosuppression varies

Effects of tetrabrominated diphenyl ether and hexabromocyclododecanes in single and complex exposure to hepatoma HepG2 cells

This study was designed to determine cytotoxic effects of PBDE-47 and HBCDs individually or with a mixture of both compounds exposure to Hep G2 cells. The results showed PBDE-47 and HBCDs induced increase of nitric oxide synthase (NOS) activity, release of NO. dissipation of mitochondria membrane potential and cell apoptosis. Exposure to HBCDs induced ROS formation. Moreover, preincubation with PTIO (NO scavanger) and N-acetylcysteine (ROS scavanger) partially reversed cytotoxic effects of these compounds. The possible mechanism is that PBDE-47 and HBCDs could boost generation of NO and/or ROS, impact mitochondria, and result in start-ups of apoptosis program. Cells exposed to mixture of both compounds and each of them showed non-apoptotic rate significant difference, but the combination of them caused more adverse effects on cells. These results Suggest that PBDE-47 and HBCDs in single and complex exposure have the cytotoxic activity of anti-proliferation and induction of apoptosis in tumor cells in vitro. (C) 2008 Elsevier B.V. All rights reserved.

Effects of hexachlorobenzene on antioxidant status of liver and brain of common carp (Cyprinus carpio)

Hexachlorobenzene (HCB)-induced oxidative damages have been published in rats while the effects have not yet been reported in fishes. Juvenile common carps (Cyprinus carpio) were exposed to waterborne HCB from 2 to 200 mu g l(-1) for 5, 10 or 20 days. Liver and brain were analyzed for various parameters of oxidative stress. There were no significant changes of glutathione (GSH) content and superoxide dismutase (SOD) activity in liver after 5 or 10 days exposure, whereas obvious drops were observed at higher concentrations after 20 days exposure. Significant decreases of GSH content and SOD activity in brain were found during all the exposure days. In brain, HCB also significantly elevated the contents of reactive oxygen species (ROS), thiobarbituric acid-reactive substances (TBARS, as an indicator of lipid peroxidation products), glutathione disulfide (GSSG), and activities of nitric oxide synthase (NOS), glutathione peroxidase (GPx), and glutathione reductase (GR), and inhibited activities of acetylcholinesterase (AchE) and glutathione S-transferase (GST). The results clearly demonstrated that environmentally possible level of HCB could result in oxidative stress in fish and brain was a sensitive target organ of HCB toxicity. (c) 2006 Elsevier Ltd. All rights reserved.

Design and characteristics of quantum cascade laser-based CO detection system

National High Technology Research and Development Program of China 2007AA03Z112；Program of Ministry of Education of China 20060183030；Program of Jilin Provincial Science and Technology Department of China 20070709；Program of Bureau of Science and Technology of Changchun City 2007107

一氧化氮（NO）对人肝癌细胞的重离子辐射增敏作用

为了探索一氧化氮（nitric oxide，NO）作为重离子治癌的辐射增敏剂的相关机理和应用前景，本课题采用NO与12C6+离子束(或X射线)辐照协同作用人肝癌细胞（SMMC-7721细胞和HepG2细胞），研究了NO与辐照相结合对两种细胞的生物学效应影响，为重离子治癌中放射增敏剂的临床应用提供一定的理论基础和实验依据。现得出结论如下： 1． 重离子辐射与X射线辐射相比，能够更有效地杀死肿瘤细胞。 2． NO能够增加肿瘤细胞的辐射敏感性。 3 NO的放射增敏效果在一定浓度范围内存在浓度效应关系。 4 NO对不同细胞系的辐射增敏作用效果并不完全相同

辐射诱导的HeLa细胞旁效应信号通路研究

随着肿瘤认识的不断深入，肿瘤外科学、肿瘤放射治疗学、肿瘤化学治疗学构成了现代肿瘤治疗学的三大支柱，而放射治疗学的研究对于肿瘤的治疗有重要的临床意义。本文通过对HeLa进行辐射来观察其产生的旁效应信号通路，从而对临床工作的起到一定的帮助。辐照过的细胞通过释放信号分子引起周围未辐照细胞产生一系列的生物学反应的现象，称之为辐射诱导的旁效应。活性氧（Reactive oxygen species, ROS）和一氧化氮（Nitric oxide, NO）是辐射诱导的旁效应信号通路中的两个重要信号分子。本文研究了这两种重要的信号分子在辐射诱导的HeLa细胞旁效应信号通路中的关系。通过微核实验，我们发现X射线以及12C6+ 辐照过的HeLa细胞及其旁观者细胞的微核形成明显增加，而1%的二甲亚砜（Dimethyl sulfoxide，DMSO，ROS清除剂）预处理X射线辐照的细胞则显著抑制了受辐照细胞及其旁观者细胞的微核形成。1 Gy的X射线辐照能够抑制细胞的增殖速率而0.5%和1%的DMSO预处理则能减少X射线的增殖抑制作用，并且DMSO预处理的效果与浓度有关：1%的DMSO比0.5%的DMSO处理更大程度的恢复了受辐照细胞的增殖速率。另一方面，接受条件培养基（Conditioned medium）的旁观者细胞的增殖速率增加，而DMSO预处理产生条件培养基的受辐照细胞则使旁观者细胞的增殖速率降低，且DMSO预处理的效果同样与其浓度相关：浓度越高，条件培养基的刺激生长作用越小。Western blotting和DAF-FM DA荧光探针检测分别显示了辐照过后细胞的诱导型一氧化氮合酶（Inducible nitric oxide synthase, iNOS）和NO水平均升高，而DMSO预处理则降低其水平。因此，我们推测在X射线辐照的HeLa细胞旁效应信号通路当中ROS是NO的上游信号。另外，我们采用培养基转移后立即加DMSO或BMS－345541（IKK/NF-κB抑制剂）的方法研究了旁观者细胞当中的旁效应信号通路。我们发现DMSO和BMS－345541均显著抑制了旁观者细胞的NO水平。因此，在旁观者细胞当中ROS与NF-κB均为NO的上游信号

Perovskite-Like Mixed Oxides (LaSrMn1-x Ni (x) O4+delta, 0 a parts per thousand currency sign x a parts per thousand currency sign 1) as Catalyst for Catalytic NO Decomposition: TPD and TPR Studies

Catalytic NO decomposition on LaSrMn1-x Ni (x) O4+delta (0 a parts per thousand currency sign x a parts per thousand currency sign 1) is investigated. The activity of NO decomposition increases dramatically after the substitution of Ni for Mn, but decreases when Mn is completely replaced by Ni (x = 1.0). The optimum value is at x = 0.8. These indicate that the catalytic performance of the samples is contributed by the synergistic effect of Mn and Ni. O-2-TPD and H-2-TPR experiments are carried out to explain the change of activity. The former indicates that only when oxygen vacancy is created, could the catalyst show enhanced activity for NO decomposition; the latter suggests that the best activity is obtained from catalyst with the most matched redox potentials (in this work, the biggest Delta T and Delta E values).

Oxygen Carrier Based on Hemoglobin/Poly(L-lysine)-block-poly(L-phenylalanine) Vesicles

An oxygen carrier was prepared by encapsulating carbonylated hemoglobin (CO-Hb) molecules into polypeptide vesicles made from poly(L-lysine)-block-poly(L-phenylalanine) (PLL-b-PPA) diblock copolymers in aqueous medium at pH 5.8. The encapsulation was confirmed by confocal laser scanning microscopy (CLSM). The morphology and size of the Vesicles were studied by field-emission scanning electron microscopy (ESEM). They had a spherical shape with it mean diameter of about 4 to 5 mu m. The encapsulation efficiency of hemoglobin was 40 wt %, and the hemoglobin content in the vesicles was 32 wt %. The CO-Hb encapsulated in the PLL-b-PPA vesicles was more stable than free CO-Hb under ambient conditions, In the presence of a O-2 atmosphere, the CO-Hb in the vesicle could be converted into oxygen-binding hemoglobin (O-2-Hb) under irradiation of visible light for 2 h. Therefore, the CO-Hb/PLL-b-PPA vesicles are expected to be used its red blood cell substitutes.

Photochemical formation of silver and gold nanostructures at the air-water interface and their electrocatalytic properties

In this paper, we report a simple method of fabricating silver and gold nanostructures at the air - water interface, which can be spontaneously assembled through the reduction of AgNO3 and HAuCl4 with ultraviolet (UV) irradiation in the presence of polyacrylic acid (PAA), respectively. It was found that the building blocks in the silver nanostructure are mainly interwoven silver nanofilaments, while those of the gold nanostructure are mainly different sizes of gold nanoparticles and some truncated gold nanoplates, and even coalescence into networks. At the air - water interface, these silver and gold nanostructures can be easily transferred onto the surface of indium tin oxide (ITO) slides and used for electrochemical measurements. After a replacement reaction with H2PdCl4, the silver nanostructure is transformed into a Ag - Pd bimetallic nanostructure, with good electrocatalytic activity for O-2 reduction. The gold nanostructure can also show high electrocatalytic activity to the oxidation of nitric oxide (NO) with a detection limit of about 10 mu M NaNO2 at S/N = 3.

Effect of strontium substitution on the activity of La2-xSrxNiO4 (x=0.0-1.2) in NO decomposition

The aim of this work is to study the effect of Sr substitution on the redox properties and catalytic activity of La2-xSrxNiO4 (x = 0.0-1.2) for NO decomposition. Results suggest that the x = 0.6 sample shows the highest activity. The characterization (TPD, TPR, etc.) of samples indicates that the x = 0.6 sample possesses suitable abilities in both oxidation and reduction, which facilitates the proceeding of oxygen desorption and NO adsorption. At temperature below 700 degrees C, the oxygen desorption is difficult, and is the rate-determining step of NO decomposition. With the increase of reaction temperature (T > 700 degrees C), the oxygen desorption is favorable and, the active adsorption of NO on the active site (NO + V-o + Ni2+ -> NO--Ni3+) turns out to be the rate-determining step. The existence of oxygen vacancy is the prerequisite condition for NO decomposition, but its quantity does not relate much to the activity.

Characterization of FeNi3 alloy in Fe-Ni-O system synthesized by citric acid combustion method

Fe-Ni-O samples, with Fe/Ni ratio ranging from 2 to 1/3, were synthesized. Samples synthesized with and without citric acid in the precursor were compared and it was found that the addition of citric acid is the necessary condition for FeNi3 formation; it was found that FeNi3 alloys were formed in these samples even when calcined in an air atmosphere. X-ray diffraction and X-ray photoelectron spectroscopy measurements were used to characterize the samples. Because of the existence of FeNi3 alloys, Fe-Ni-O samples showed strong reactivity to NO and NO + O-2 but were inert to O-2 alone.

Effect of Ce and MgO on NO decomposition over La1-x-Ce-x-Sr-Ni-O/MgO

Ce and MgO were added simultaneously to La-Sr-Ni-O catalyst and a substantial enhancement of activity for NO decomposition was observed, which may be attributed to the formation of a new highly active site caused by the addition of Ce and MgO.

Effect of valence of copper in La2-xThxCuO4 on NO decomposition reaction

NO decomposition reaction was investigated over La2-xThxCuO4, in which the valence of copper was controlled by Th substitution and was characterized by XPS measurement. A close correlation between the valence of copper and the activity was observed. The activity increased with the decrease of the average oxidation number of copper, and increased with the increase of Cu+ content, suggesting that the transition metal with low valence (Cu+) is active for the reaction in the present cases.