富氢水对γ射线照射Beagle犬淋巴细胞基因表达谱的影响

目的 利用基因芯片技术研究富氢水对γ射线照射后Beagle犬外周血淋巴细胞基因表达的影响.方法 将雄性Beagle犬随机分为对照组、单纯照射组和富氢水组(n=5),采用基因芯片技术对2.0 Gy60Coγ射线照射后6h各组Beagle犬外周血淋巴细胞的差异表达基因进行筛选,利用CGO (gene ontology)和KEGG(Kyoto encyclopedia of genes andgenomes)数据库对差异表达基因进行生物信息学分析,并应用实时荧光定量PCR技术对基因芯片结果进行验证.结果 单纯照射组筛选出差异表达2倍以上的基因4 730条,富氢水组筛选出差异表达2倍以上的基因4 493条,单纯照射组与富氢水组共同差异表达2倍以上的基因有1 606条;单纯照射组的差异表达基因对应的生物学过程、细胞组分及分子功能分别有10、9、3个功能簇,富氢水组差异表达基因对应的生物学过程、细胞组分及分子功能分别有15、3、4个功能簇.单纯照射组差异表达基因涉及19条生物学通路,富氢水组差异表达基因涉及24条生物学通路,单纯照射组与富氢水组的差异表达基因有5条共同生物学通路.选择2条差异表达基因进行mRNA水平的验证,PCR扩增结果与芯片结果具有良好的一致性.结论 富氢水对γ射线照射后Beagle犬外周血淋巴细胞基因表达的影响,可能涉及多种生物学过程、细胞组分、分子功能的改变及多条信号通路的激活.     

Role of Aggregatibacter actinomycetemcomitans in glutathione catabolism

Introduction:  Our previous studies demonstrated that three enzymes, γ-glutamyltransferase (GGT), cysteinylglycinase (CGase) and cystalysin, are required for the catabolism of glutathione to produce hydrogen sulfide (H₂S) in Treponema denticola . In this study, we examined glutathione catabolism in Aggregatibacter actinomycetemcomitans .
Methods:  The GGT and CGase of A. actinomycetemcomitans were determined by biological methods and GGT was characterized using a molecular biological approach.
Results:  A. actinomycetemcomitans showed GGT and CGase activity, but could not produce H₂S from glutathione. The addition of recombinant T. denticola cystalysin, an l -cysteine desulfhydrase, to whole cells of A. actinomycetemcomitans resulted in the production of H₂S from glutathione. Subsequently, we cloned A. actinomycetemcomitans GGT gene ( ggt ) and overexpressed the 63 kDa GGT protein. The recombinant A. actinomycetemcomitans GGT was purified and identified. The K _cat/ K _m of the recombinant GGT from N -γ- l -glutamyl-4-nitroaniline as substrate was 31/μ m /min. The activity of GGT was optimum at pH 6.9–7.1 and enhanced by thiol-containing compounds.
Conclusion:  The results demonstrated that A. actinomycetemcomitans had GGT and CGase activities and that the GGT was characterized. The possible role of A. actinomycetemcomitans in glutathione metabolism and H₂S production from oral bacteria was discussed.     

Gaseous mediators in resolution of inflammation

There are numerous gaseous substances that can act as signaling molecules, but the best characterized of these are nitric oxide, hydrogen sulfide and carbon monoxide. Each has been shown to play important roles in many physiological and pathophysiological processes. This article is focused on the effects of these gasotransmitters in the context of inflammation. There is considerable overlap in the actions of nitric oxide, hydrogen sulfide and carbon monoxide with respect to inflammation, and these mediators appear to act primarily as anti-inflammatory substances, promoting resolution of inflammatory processes. They also have protective and pro-healing effects in some tissues, such as the gastrointestinal tract and lung. Over the past two decades, significant progress has been made in the development of novel anti-inflammatory and cytoprotective drugs that release of one or more of these gaseous mediators.     

A New Approach to Morphology Studies on Diacrylate Polymer Networks Using X‐Ray Powder Diffraction

X‐ray powder diffraction (XRPD) and Fourier transform infrared (FTIR) spectroscopy are used to characterize the morphology of diacrylate polymer networks, obtained by photoinduced homo‐ and copolymerizations. XRPD reveals the presence of three sized groups of microgel agglomerates. The dimensions of the microgel agglomerates (D) and the degree of conversion (DC) are explained by the monomer chemical structure, the strength of hydrogen bonds, and relate to selected polymer mechanical properties. The D value increases and the DC decreases as the strength of the hydrogen bonds increases. Copolymerization with monomers lacking groups forming strong hydrogen bonds results in more homogeneous networks with improved mechanical properties.

     

经皮穴位电刺激不同时间对雷公藤甲素致大鼠急性肝损伤的影响

目的 观察经皮穴位电刺激（transcutanclus electrical acupoint stimulation,TEAS）不同刺激时间对雷公藤甲素致大鼠急性肝损伤的保护作用。方法 将50只SD大鼠随机分为空白组、模型组、TEAS Ⅰ组（刺激20 min）,TEAS Ⅱ组（刺激30 min）、TEAS Ⅲ组（刺激40 min）,以雷公藤甲素灌胃法复制急性肝损伤模型。TEAS各组刺激“足三里”穴,每日1次,连续5 d。观察肝脏组织形态学变化,检测血清天冬氨酸氨基转移酶（aspartate aminotransferase,AST）、丙氨酸氨基转移酶（alanine aminotransferase,ALT）及肝组织丙二醛（malondialdehyde,MDA）、肿瘤坏死因子- α（tumor necrosis factor- α,TNF- α）、白介素- 10（interleukin- 10,IL- 10）、硫化氢的含量。结果 模型组大鼠肝索排列紊乱,肝窦扩张,肝细胞水肿、脂肪变性、坏死;各TEAS组肝脏病理变化较模型组减轻。与空白组比较,模型组大鼠血清ALT、AST及肝组织MDA、TNF- α含量明显升高（P＜0.05）,硫化氢含量明显降低（P＜0.05）,肝组织IL- 10含量无明显变化（P＞0.05）。与模型组比较,TEAS Ⅰ、Ⅱ、Ⅲ组大鼠血清AST、ALT含量和肝组织MDA、TNF- α含量明显降低（P<0.05）或呈降低趋势（P>0.05）,硫化氢含量明显升高（P<0.05）。其中TEAS Ⅲ组与TEAS Ⅰ、Ⅱ组各指标比较,差异均具有统计学意义（P＜0.05）。结论 TEAS能减轻雷公藤甲素对肝组织的损伤,且较长时间（40 min）刺激的保护作用更为明显。     

Low-temperature, manganese oxide-based, thermochemical water splitting cycle

Thermochemical cycles that split water into stoichiometric amounts of hydrogen and oxygen below 1,000 °C, and do not involve toxic or corrosive intermediates, are highly desirable because they can convert heat into chemical energy in the form of hydrogen. We report a manganese-based thermochemical cycle with a highest operating temperature of 850 °C that is completely recyclable and does not involve toxic or corrosive components. The thermochemical cycle utilizes redox reactions of Mn(II)/Mn(III) oxides. The shuttling of Na(+) into and out of the manganese oxides in the hydrogen and oxygen evolution steps, respectively, provides the key thermodynamic driving forces and allows for the cycle to be closed at temperatures below 1,000 °C. The production of hydrogen and oxygen is fully reproducible for at least five cycles.     

漂白剂对玻璃离子水门汀类材料充填Ⅴ类洞边缘微渗漏的影响

目的评估漂白凝胶和洁白牙贴对3种不同的玻璃离子水门汀类材料边缘微渗漏的影响。方法在45颗离体健康前磨牙的颊舌侧制备Ⅴ类洞,随机分为A、B、C组,分别使用加强型玻璃离子水门汀KetacTM Molar Easymix、复合体F2000、复合体Dyract AP充填,每个大组再分为3个亚组,第1组和第2组分别使用质量分数14％过氧化氢（HP）洁白牙贴和10％过氧化脲（CP）凝胶进行漂白,第3组为对照组。所有样本置入37 ℃蒸馏水中保存7 d后冷热循环500次,然后进行漂白。漂白21 d后置于碱性品红溶液中染色24 h,沿牙体长轴通过充填体中央颊舌向剖开牙齿,体视显微镜下观察并测量染料渗入窝洞壁的深度。结果2种漂白方式对充填体边缘微渗漏的影响没有明显差异（P>0.05）;与对照组相比,2种漂白方式对B、C组的微渗漏均没有产生明显影响（P>0.05）,但均可使A组的微渗漏增加（P<0.05）。结论10％CP凝胶和14％HP洁白牙贴对充填体边缘微渗漏的影响无明显差异;漂白不会影响复合体的微渗漏,但会增加加强型玻璃离子水门汀的微渗漏。     

Combined effects of hydrogen sulfide and lipopolysaccharide on osteoclast differentiation in rats

Background: Lipopolysaccharide (LPS) stimulates osteoclast differentiation through toll‐like receptors (TLRs) 2 and 4, and hydrogen sulfide (H₂S) induces osteoclast differentiation. If H₂S activates TLRs, H₂S may enhance the effects of LPS on osteoclast differentiation. The purpose of the present study is to examine the combined effects of sodium hydrogen sulfide (NaHS, an H₂S donor drug) and LPS on osteoclast differentiation and TLR expression in rat periodontal tissue. Methods: Twenty‐eight male Wistar rats (8 weeks old) were divided into four groups (n = 7 per group): a control (no treatment) group and three experimental groups (NaHS group, LPS group, and a combination [NaHS + LPS] group). At 1 day after topical application of NaHS and/or Porphyromonas gingivalis LPS into the gingival sulcus of first molars, the number of tartrate‐resistant acid phosphate (TRAP)‐positive osteoclasts in the periodontal tissue was counted. Expression of TLR2 and TLR4 mRNAs and proteins in the gingival was also assessed. Results: The number of TRAP‐positive osteoclasts was significantly higher in the combination group than in any other group (P <0.01). The combination group had 11.0‐fold higher TLR4 mRNA levels than the control group. TLR4 protein levels were also higher in the combination group than in the NaHS or LPS group. However, the TLR2 mRNA and protein levels were not significantly different in the combination group and the LPS group. Conclusion: In rat periodontal tissue, NaHS and LPS had an additive effect on osteoclast differentiation through activation of the TLR4 pathway but not the TLR2 pathway.