Structural comparison of (pentamethylcyclopentadienyl)iridium(III) azido complexes containing potentially N,S-bidentate N-heterocyclic thiolates: 2- or 8-quinolinethiolate and benzimidazole-2-thiolate

The crystal structures of mononuclear (azido)(pentamethylcyclopentadienyl)iridium(III) complexes bearing 2- or 8-quinolinethiolate (n-Sqn⁻), [Cp^∗Ir(N₃)(n-Sqn)] {n = 2 (1) or 8 (2); Cp^∗ = η⁵-C₅Me₅} have been determined by X-ray analysis. The 2-Sqn complex, 1, acquires severe steric strains in the four-membered κ²N,S chelate ring, while the 8-Sqn isomer, 2, forms a strain-free five-membered planar κ²N,S chelate ring. It has also been revealed that the corresponding benzimidazole-2-thiolate (Hbimt⁻) complex, which was obtained similarly to the above n-Sqn complexes from [Cp^∗Ir(N₃)₂]₂ and Na(Hbimt), takes an unsymmetrical dinuclear structure bridged by two Hbimt⁻ ligands with different bonding modes, [Cp^∗Ir(N₃){μ(S:N¹)-Hbimt}{μ(S:S)-Hbimt}Ir(N₃)Cp^∗] · MeOH (3).     

Mechanical loading of orthodontic miniscrews - significance and problems: an experimental study

Orthodontic miniscrews are exposed to three mechanical loading phases during clinical use: torsional loading upon insertion, flexural loading during anchorage function, and torsional loading upon removal. The aim of this study was to simulate clinical loading conditions for different types of orthodontic miniscrews in vitro to quantify the effects of combined torsional and bending stress. Various orthodontic miniscrew systems (Lomas, Dual-top, Aarhus anchorage, Tomas-pin and T.I.T.A.N.-pin) comprising 10 samples each were subjected to the following loading sequences in vitro: a torsional load corresponding to manual insertion with limited torque; and flexural loading at two different insertion depths. For all screw systems with torsional pre-loading (simulating insertion), subsequent flexural loading (simulating anchorage) yielded permanent deformations of approximately 0.15-0.25 mm, depending on the insertion depth. Since EDX analysis revealed comparable elemental compositions for the different screw systems, the differences in mechanical properties are attributed to screw design. Torsional loading during screw insertion may cause premature mechanical weakening and needs to be minimized. Unless fully inserted, screws show pronounced plastic deformation and hence fracture risk under subsequent flexural loading.     

SCP诱导人肝癌细胞凋亡与bcl-2基因表达的关系

目的探讨鲨鱼软骨制剂(SCP)诱导人肝癌细胞系(SMMC7721)凋亡的作用机制.方法以不同浓度SCP加入体外培养的SMMC7721细胞中,用MTT比色法检测细胞存活率;Hoechst33342/PI荧光染色,荧光显微镜分析凋亡细胞百分率;流式细胞术进行细胞凋亡定量;琼脂糖凝胶电泳检测DNA梯状条带;免疫细胞化学染色法检测Bcl-2蛋白的表达.结果 SCP明显抑制SMMC7721细胞生长,IC50值为1.25mg/ml;荧光显微镜下可见50%以上细胞为凋亡细胞的形态学改变;琼脂糖凝胶电泳呈现梯状条带(DNA ladder);免疫细胞化学检测显示SCP诱导人肝癌细胞凋亡过程中Bcl-2表达明显降低.结论 SCP诱导SMMC7721细胞凋亡,可能与下调Bcl-2表达有关.     

丹参酮对阿尔茨海默病样大鼠海马内白介素1β和白介素6 mRNA表达的影响

目的探讨丹参酮(tanshinone, Tan)抗β-淀粉样肽神经元毒性的分子机制.方法应用凝聚态β-淀粉样肽1-40片段(amyloid β-peptide1-40, Aβ1-40)在大鼠双侧海马齿状回背侧细胞带进行微量注射以建立拟人类阿尔茨海默病(Alzheimer's disease, AD)样动物模型;采用明暗箱被动回避法、穿梭法测试学习记忆功能;用半定量逆转录-聚合酶链反应(RT-PCR)方法测定海马内白介素1β(IL-1β)和白介素6(IL-6)mRNA含量;以丹参酮(tanshinone, Tan)(50mg/ kg)对Aβ1-40处理的大鼠连续灌胃14d,观察其干预效果.结果海马内注射Aβ1-40 14 d后,经行为学检测大鼠学习记忆功能明显减退,海马内IL-1β和IL-6 mRNA表达均显著高于对照组(P< 0.01);Tan(50mg/ kg)连续灌胃14 d能显著抑制大鼠学习记忆功能的减退和上述病理变化.结论 Tan对Aβ1-40诱导的大鼠学习记忆功能障碍具有显著改善作用,并能有效地抑制其海马内IL-1β和IL-6 mRNA的升高,这可能为Tan治疗AD样大鼠的分子机制.     

New developments in fish amino acid nutrition: towards functional and environmentally oriented aquafeeds

Recent evidence shows that some amino acids and their metabolites are important regulators of key metabolic pathways that are necessary for maintenance, growth, feed intake, nutrient utilization, immunity, behavior, larval metamorphosis, reproduction, as well as resistance to environmental stressors and pathogenic organisms in various fishes. Therefore, conventional definitions on essential and nonessential amino acids for fish are challenged by numerous discoveries that taurine, glutamine, glycine, proline and hydroxyproline promote growth, development, and health of aquatic animals. On the basis of their crucial roles in cell metabolism and physiology, we anticipate that dietary supplementation with specific amino acids may be beneficial for: (1) increasing the chemo-attractive property and nutritional value of aquafeeds with low fishmeal inclusion; (2) optimizing efficiency of metabolic transformation in juvenile and sub-adult fishes; (3) surpressing aggressive behaviors and cannibalism; (4) increasing larval performance and survival; (5) mediating timing and efficiency of spawning; (6) improving fillet taste and texture; and (7) enhancing immunity and tolerance to environmental stresses. Functional amino acids hold great promise for development of balanced aquafeeds to enhance the efficiency and profitability of global aquaculture production.     

Characterization of mycorrhizal fungi isolated from the threatened Cypripedium macranthos in a northern island of Japan: two phylogenetically distinct fungi associated with the orchid

We isolated Rhizoctonia-like fungi from populations of the threatened orchid Cypripedium macranthos. In ultrastructural observations of the septa, the isolates had a flattened imperforate parenthesome consisting of two electron-dense membranes bordered by an internal electron-lucent zone, identical to the septal ultrastructure of Rhizoctonia repens (teleomorph Tulasnella), a mycorrhizal fungus of many orchid species. However, hyphae of the isolates did not fuse with those of known tester strains of R. repens and grew less than half as fast as those of R. repens. In phylogenetic analyses, sequences for rDNA and internal transcribed spacer (ITS) regions of the isolates were distinct from those of the taxonomically identified species of Tulasnella. On the basis of the ITS sequences, the isolates clustered into two groups that corresponded exactly with the clades demonstrated for other Cypripedium spp. from Eurasia and North America despite the geographical separation, suggesting high specificity in the Cypripedium–fungus association. In addition, the two phylogenetic groups corresponded to two different plant clones at different developmental stages. The fungi from one clone constituted one group and did not belong to the other fungal group isolated from the other clone. The possibility of switching to a new mycorrhizal partner during the orchid’s lifetime is discussed.     

香蕉枯萎病拮抗放线菌Da08006的筛选与鉴定

以尖孢镰刀菌4号小种为指示菌株,对海南尖峰岭原始森林和发病香蕉园健康植株根际土壤的放线菌进行筛选,获得一株具有较强拮抗作用、遗传稳定的放线菌Da08006.通过形态特征、生理生化特征、16S rDNA序列及其系统发育分析研究,鉴定菌株Da08006为Streptomyces morookaense.     

Identification of 4-hydroxyquinolines inhibitors of p300/CBP histone acetyltransferases

We identified a series of 4-hydroxyquinolines bearing a C1 to C15 alkyl chain at the C2 position and a carbethoxy/carboxy group at the C3 position of the quinoline nucleus (MC compounds), endowed with selective inhibitory activity against the p300/CBP HAT enzymes. Enzyme inhibition was investigated using in vitro HAT assays and by western blot analysis of cellular lysates to examine the acetylation levels of histone H3 and α-tubulin. When tested in U937 cells, some compounds displayed pro-apoptotic or cytodifferentiating properties.     

High-sensitivity immunochromatographic assay for fumonisin B1 based on indirect antibody labeling

Objective

To develop a high-sensitivity immunochromatographic test for fumonisin B1 in plant extracts.

Results

Unlike conventional immunochromatographic tests, this assay is performed in two stages: competitive reaction with free specific antibodies and identifying immune complexes by their interaction with the anti-species antibody-conjugated gold nanoparticles. The use of a new geometry for the test strip membranes and a novel reagent application method ensures the proper order of these stages without additional manipulations. The contact of the ready-to-use test strip with the liquid sample suffices in initiating all stages of the assay and obtaining test results. The developed test was used on corn extracts; its instrumental limit of fumonisin B1 detection was 0.6 ng ml^?1 at 15 min of assay duration.

Conclusions

The proposed approach is flexible and can be used for a wide range of low molecular compounds. The use of anti-species antibody-conjugated gold nanoparticles in immunochromatography significantly facilitates the development of test systems by eliminating the need to synthesize and characterize the conjugates with specific antibodies for each new compound to be detected.