CXCR2 is critical to hyperoxia-induced lung injury

Hyperoxia-induced lung injury is characterized by infiltration of activated neutrophils in conjunction with endothelial and epithelial cell injury, followed by fibrogenesis. Specific mechanisms recruiting neutrophils to the lung during hyperoxia-induced lung injury have not been fully elucidated. Because CXCL1 and CXCL2/3, acting through CXCR2, are potent neutrophil chemoattractants, we investigated their role in mediating hyperoxia-induced lung injury. Under variable concentrations of oxygen, murine survival during hyperoxia-induced lung injury was dose dependent. Eighty percent oxygen was associated with 50% mortality at 6 days, while greater oxygen concentrations were more lethal. Using 80% oxygen, we found that lungs harvested at day 6 demonstrated markedly increased neutrophil sequestration and lung injury. Expression of CXCR2 ligands paralleled neutrophil recruitment to the lung and CXCR2 mRNA expression. Inhibition of CXC chemokine ligands/CXCR2 interaction using CXCR2(-/-) mice exposed to hyperoxia significantly reduced neutrophil sequestration and lung injury, and led to a significant survival advantage as compared with CXCR2(+/+) mice. These findings demonstrate that CXC chemokine ligand/CXCR2 biological axis is critical during the pathogenesis of hyperoxia-induced lung injury.     

New molybdenum(VI) catalysts for the epoxidation of cyclohexene: synthesis, reactivity and crystal structures

Compounds 1-6 of the type MoO₂X₂L₂ (X=F, Cl, Br; L=OPMePh₂, OPPh₃) have been prepared in order to investigate the variation in catalytic activity with changes in electronic and steric properties. All six complexes catalyze the epoxidation of cyclohexene with tert-butylhydroperoxide, and the species with X=Cl and L=OPMePh₂ (2) displays the best activity with 83% conversion and 90% selectivity in one hour at ambient atmosphere. These inexpensive and easily prepared dioxo catalysts are stable to air and water. Reactions of the dioxo compounds with H₂O₂ and t-BuOOH have also been carried out. The structures of MoO₂F₂(OPMePh₂)₂ (1) and the product of its reaction with H₂O₂, MoO(O₂)₂(OPMePh₂)₂ (7) have been solved by single crystal X-ray diffraction.     

盐生杜氏藻甘油-3-磷酸脱氢酶的分离纯化及其特性的研究

利用ＰＥＧ分级,ＤＥＡＥ离子交换层析,ＢｌｕｅＳｅｐｈａｒｏｓｅ拟亲和层析,ＭｏｎｏＱ离子交换层析等手段,分离纯化盐生杜氏藻（Ｄｕｎａｌｉｅｌａｓａｌｉｎａ（Ｄｕｎａｌ）Ｔｅｏｄ．）甘油三磷酸（Ｇ３Ｐ）脱氢酶（ＥＣ１．１．１．８）,得到比活为１２．６Ｕ／ｍｇ的电泳纯的酶,并对此酶的生化特性进行了研究。４％～２０％非变性聚丙烯酰胺梯度凝胶电泳测得全酶分子量约为２７０ｋＤ,ＳＤＳＰＡＧＥ表明该酶只有一种分子量约为６５ｋＤ的亚基,据此推测该酶应为同四聚体。酶催化磷酸二羟丙酮（ＤＨＡＰ）还原的最适ｐＨ值为７．５,催化Ｇ３Ｐ脱氢的最适ｐＨ值为１０。该酶对４个底物还原型辅酶Ⅰ（ＮＡＤＨ）,二磷酸吡啶核苷酸（ＤＨＡＰ）,辅酶Ⅰ（ＮＡＤ）,Ｇ３Ｐ的表观Ｋｍ值分别为６３μｍｏｌ／Ｌ,２７２μｍｏｌ／Ｌ,１．５３ｍｍｏｌ／Ｌ,６．５２ｍｍｏｌ／Ｌ。该酶在保存过程中易失活。ＮＡＤＨ能降低酶失活的速度,而ＮＡＤ则不然。低浓度ＮａＣｌ对酶略有保护作用,但高浓度ＮａＣｌ加快酶的失活,且浓度越高效应越明显。     

α—硫辛酸对6—羟多巴胺诱导的PC12细胞凋亡的影响

PC12 cell line, a clonal cell line derived from a pheochromocytoma of rat adrenal medulla, was used as a model of dopaminergic neuron in vitro to study the effect of alpha-lipoic acid on the 6-OHDA induced apoptosis. The results from MTT method show that 6-OHDA decreased the cell survival rate obviously. Through TUNEL (TdT-mediated dUTP-biotion nick end labeling) and Flow cytometer (FCM) detection, we found that 6-OHDA triggered cell apoptosis and induced necrosis. It was confirmed by the different percentage of cell survival rate and apoptosis concluded from FCM and MTT. alpha-lipoic acid was used as antioxidant to protect the cell from 6-OHDA's injury. The result indicateed that alpha-lipoic acid can partly prevent apoptosis induced by 6-OHDA but fail to prevent necrosis since it can decrease the apoptotic cell from 20.09% to 3.09%, just as increased cell survival rate from 56.8% to 72.6% but can not reach the normal level showed by MTT assay. Biochemical approach showed the cell's antioxidant ability especial for SOD activity and GSH content increased after the treatment of alpha-lipoic acid. The data suggest that alpha-lipoic acid may protect PC12 cells from apoptosis induced by 6-OHDA through the antioxidant path.     

Electron and light microscopy of neutrophil responses in mice vaccinated and challenged with third-stage infective hookworm (Ancylostoma caninum) larvae.

The role of neutrophils in mediating host inflammation was examined in mice vaccinated with living third-stage infective hookworm larvae (L₃). Mice were vaccinated by oral immunization with 500 L₃ (Ancylostoma caninum) once every 2 weeks for a total of three immunizations. The vaccinated mice were then challenged intraperitoneally with 2000 L_3, 1 week after the final immunization. To stimulate peritoneal production of neutrophils, 2 ml of 2% glycogen were injected intraperitoneally at 16 h prior to the challenge infection. Neutrophils were found to comprise 85% of the peritoneal cell population. L₃ from the challenge infection were collected and then examined at timed intervals by inverted light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Greater than a fivefold increase in the total numbers of peritoneal cells was noted in the vaccinated mice as compared to unvaccinated mice. In the peritoneal cavity of vaccinated mice, the neutrophils adhered to the L₃ within 2 h, and over 55% of the L₃ were surround by clusters of neutrophils to form a sausage-like sheath 4 h later. At 24–72 h after challenge, almost all of the L₃ recovered from the vaccinated mice were covered with thick clusters of cells. Both SEM and TEM demonstrated extensive ultrastructural damage to the L_3. In contrast, the L₃ recovered from the unvaccinated mice appeared to be unaffected by neutrophils. These studies suggest that neutrophils, like macrophages, can have an important role as effector cells in L₃-vaccinated mice.     

Diblock glycopolymers promote colloidal stability of polyplexes and effective pDNA and siRNA delivery under physiological salt and serum conditions

A series of glycopolymers composed of 2-deoxy-2-methacrylamido glucopyranose (MAG) and the primary amine-containing N-(2-aminoethyl) methacrylamide (AEMA) were synthesized via aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization. The colloidal stability of the polyplexes formed with three diblock glycopolymers and pDNA was assessed using dynamic light scattering, and the polyplexes were found to be stable against aggregation in the presence of salt and serum over the 4 h time period studied. Delivery experiments were performed in vitro to examine the cellular uptake, transfection efficiency, and cytotoxicity of the glycopolymer/pDNA polyplexes in cultured HeLa cells and the diblock copolymer with the shortest AEMA block was found to be the most effective. Additionally, the ability of the diblock glycopolymers to deliver siRNA to U-87 (glioblastoma) cells was screened, and the diblock copolymer with the longest AEMA block was found to have gene knockdown efficacy similar to Lipofectamine 2000.     

Aerobic denitrification by novel isolated strain using NO-₂-N as nitrogen source

Biological denitrification reaction can be achieved under aerobic environment. Few aerobic denitrifiers using nitrite as sole nitrogen source were identified. Using nitrite as the sole nitrogen source, this work assessed the denitrification activity of yy7, an aerobic heterotrophic denitrifier identified as Pseudomonas sp. (94% similarity) by 16S rRNA sequencing analysis. The logistic equation describes the cell growth curve, yielding a generation time of 2.9h at an initial 18 mg l(-1)NO(-)?-N. Reduction of NO(-)?-N was primarily achieved during its logarithmic growth phase, and was accompanied by an increase in suspension pH and near complete consumption of dissolved oxygen. Three genes relating to nirK, norB, and nosZ were noted to involve in isolate strain. Isolate yy7 can survive and remove up to 40 mg l(-1)NO(-)?-N and, hence, can be applied as an effective aerobic denitrifier during simultaneous nitrification and denitrification via nitrite processes.