Architecture of the media of the arterial vessels in the dog brain: A scanning electron-microscopic study

Summary The architecture of the media of arterial vessels in dog brain was investigated using scanning electron microscopy. The arrangement and shape of the circularly-oriented smooth muscle cells varied with vessel diameter: The arteries (>100 m in diameter) had 4–10 layers of spindle-shaped smooth muscle cells; the muscular arterioles (30–100 m), 2–3 layers of spindle-shaped smooth muscle cells; the terminal arterioles (10–30 m), a compact layer of spindle-shaped smooth muscle cells with more dominant nodular or rod-like processes and thin lateral processes; and the precapillary arterioles (5–15 m), a less compact layer of branched smooth muscle cells.Longitudinally-oriented muscles were observed in the medio-adventitial border. The distribution and arrangement of these muscles varied with vessel size: in the large arteries (> 300 m in diameter), at the branching sites only; in the small arteries (100–300 m), at both the branching and non-branching sites; in the muscular arterioles, at both the branching and non-branching sites in a reticular arrangement with some muscle cells having an asteroid appearance; in the terminal aterioles, only asteroid-like muscle cells were found at the branching and non-branching sites.     

手机触屏多重耐药菌的分离鉴定

目的 明确手机触屏的菌群分布,对耐药菌株进行分型鉴定,指导触屏手机的正确清洁、使用方式。方法 对20名在校学生与20名医护人员手机触屏进行采样、增菌培养,以等面积电梯按钮作为对照组。使用药敏试验筛选对普通抗生素有耐药能力的菌株,对其进行克隆测序、PCR耐药位点检测和生化检测,鉴定具有耐药性细菌的种类。结果 医护人员手机触屏菌液浓度和菌落数与对照组间差异有统计学意义（t=2.281,P<0.05;t=2.185,P<0.05）,在校学生组与医护人员组以及对照组间差异无统计学意义;在校学生组与医护人员组均分离出具有多重耐药的菌株——铜绿假单胞菌。结论 手机屏幕表面存在多种细菌,经鉴定大多为大肠埃希菌、金黄色葡萄球菌、表皮葡萄球菌和草绿色链球菌等,同时存在多重耐药性铜绿假单胞菌,定期对手机触屏进行清洁消毒势在必行。     

分泌性中耳炎大鼠咽鼓管鼓室β-防御素的表达

目的检测大鼠β防御素(ratβ-defensin,rBD)在分泌性中耳炎大鼠咽鼓管鼓室的表达,探讨β防御素在分泌性中耳炎发病机制中的作用。方法排除中耳感染的清洁级SD大鼠48只,随机分为4组,前3组36只行颈部切口经右侧听泡注入脂多糖(lipopolysaccharide,LPS)溶液(1mg/mL)30μL制作分泌性中耳炎动物模型,造模后分别于第1、3、7天断头取咽鼓管鼓室黏膜;对照组12只右侧听泡注入生理盐水30μL,左侧听泡作为正常组,3d后断头取咽鼓管鼓室黏膜。逆转录聚合酶链反应(RT-PCR)检测咽鼓管鼓室rBD-1mRNA和rBD-2mRNA的表达。结果正常大鼠咽鼓管鼓室存在rBD-1和rBD-2的表达,且rBD-1的表达较rBD-2强,差异有统计学意义;造模后第1、3、7天,rBD-1表达变化不明显;rBD-2则在造模后第1、3天明显增加,差异有统计学意义,第7天渐回复到正常水平。结论在大鼠,rBD-1可能参与正常咽鼓管鼓室的防御功能,造模后rBD-2的表达增加可能与病原体入侵后的清除相关。     

The complexation of metal cations by D-galacturonic acid: a spectroscopic study

Solid complexes of D-galacturonic acid (GalA) with cobalt(II), copper(II), nickel(II) and oxovanadium(IV) (1-4) were prepared and characterised. The metal-to-ligand molar ratio was 1:2 for complexes 1-3 and 1:1 for complex 4. The alpha- and beta-anomers of GalA were detected in all the complexes in solid state and in solutions. An addition of small amounts of the paramagnetic complexes to the D2O solution of pure ligand led to NMR line broadening of some 1H and 13C nuclei. This broadening was sensitive to the anomeric state of GalA in the case of complexes 1 and 4. NMR and vibrational spectroscopic data indicate the formation of carboxylate complexes of all the cations, while noncarboxylic oxygens are also involved into the metal bonding in some cases. VCD spectra of complexes 1-4 in D2O and Me2SO-d6 solutions confirm that GalA carboxylic group may participate in the formation of optically active species around the metal cation. Possible ways of GalA coordination by metal cations of this study were proposed and discussed.     

植物种群表观竞争机制及其研究进展

植物表观竞争既影响群落结构和组成,也与生态系统功能密切相关。目前,国内尚缺乏对植物表观竞争的实验研究和机制探索。对植物表观竞争概念和研究进展进行了系统梳理和阶段性总结,分析了草食动物为媒介的表观竞争主要通过食物和生境介导植物竞争过程,以及ELP-采食者关系对表观竞争的影响;植物参与的表观竞争通常与资源竞争共同作用;AM真菌为媒介的表观竞争不仅受到宿主植物菌根依赖性的影响,还与AM真菌对资源的需求和环境资源供给状况有密切关系。未来研究既要注重实验设计的合理性,也要考虑测定方法和评价参数的有效性;重视植物群落和生态系统水平上表观竞争的功能研究。这不仅能够为植物群落结构和物种共存提供机制性解释,而且能够丰富经典的植物竞争理论和多营养级相互作用的食物网理论。     

New embedding medium for sectioning undecalcified bone

Methylmethacrylate (MMA) is the most commonly used embedding medium for sectioning undecalcified bone; however, a number of problems exist with its use in a research laboratory. MMA requires a long infiltration time and temperature control, and it reacts with many polymers. We used Kleer Set resin? as an alternative embedding medium for sectioning undecalcified bone specimens. Fluorochrome labeled bone specimens were sectioned transversely using a ground section technique and longitudinally on a sledge macrotome. The slides were viewed using both transmitted light and epifluorescence microscopy. High quality sections were obtained using Kleer Set resin? for both sectioning techniques. We have shown that this new embedding medium is simpler, safer, quicker to use and does not interfere with visualization of fluorochromes.     

重组肺炎链球菌甘油脱氢酶活性及晶体培养的初步分析

甘油脱氢酶能够氧化胞内甘油为代谢活动提供能量,并参与调控与宿主粘附相关细菌蛋白质的表达,是潜在的抗菌药物靶点. 本文利用大肠杆菌BL21原核表达肺炎链球菌甘油脱氢酶,获得大量上清表达的目的蛋白. 再用Ni-NAT亲和层析、DEAE离子交换层析以及Superdex 200分子筛进行纯化. 经数据拟合,证实该酶在溶液中以同源二聚体形式存在. 光谱实验证实该重组表达甘油脱氢酶仍具有氧化甘油生成1, 3-二羟基丙酮的活性. 用Hampton试剂盒初筛晶体及棋盘法优化晶体,在0.1 mol/L Bicine PH 9.6,13% PEG MME 5000,0.2 mol/L KSCN,4% Dioxone条件下,得到了晶型好且有一定衍射能力的单晶,为解析肺炎链球菌甘油脱氢酶的三维结构及研究结构与酶活之间的关系奠定了基础.     

A newly identified group of adolescents at “invisible” risk for psychopathology and suicidal behavior: findings from the SEYLE study

This study explored the prevalence of risk behaviors (excessive alcohol use, illegal drug use, heavy smoking, reduced sleep, overweight, underweight, sedentary behavior, high use of Internet/TV/videogames for reasons not related to school or work, and truancy), and their association with psychopathology and self‐destructive behaviors, in a sample of 12,395 adolescents recruited in randomly selected schools across 11 European countries. Latent class analysis identified three groups of adolescents: a low‐risk group (57.8%) including pupils with low or very low frequency of risk behaviors; a high‐risk group (13.2%) including pupils who scored high on all risk behaviors, and a third group (“invisible” risk, 29%) including pupils who were positive for high use of Internet/TV/videogames for reasons not related to school or work, sedentary behavior and reduced sleep. Pupils in the “invisible” risk group, compared with the high‐risk group, had a similar prevalence of suicidal thoughts (42.2% vs. 44%), anxiety (8% vs. 9.2%), subthreshold depression (33.2% vs. 34%) and depression (13.4% vs. 14.7%). The prevalence of suicide attempts was 5.9% in the “invisible” group, 10.1% in the high‐risk group and 1.7% in the low‐risk group. The prevalence of all risk behaviors increased with age and most of them were significantly more frequent among boys. Girls were significantly more likely to experience internalizing (emotional) psychiatric symptoms. The “invisible” group may represent an important new intervention target group for potentially reducing psychopathology and other untoward outcomes in adolescence, including suicidal behavior.     

Effect of particle size and microbial phytase on phytate degradation in incubated maize and soybean meal

The objective of the study was to evaluate the effect of screen size (1, 2 and 3 mm) and microbial phytase (0 and 1000 FTU/kg as-fed) on phytate degradation in maize (100% maize), soybean meal (100% SBM) and maize–SBM (75% maize and 25% SBM) incubated in water for 0, 2, 4, 8 and 24 h at 38°C. Samples were analysed for pH, dry matter and phytate phosphorus (P). Particle size distribution (PSD) and average particle size (APS) of samples were measured by the Laser Diffraction and Bygholm method. PSD differed between the two methods, whereas APS was similar. Decreasing screen size from 3 to 1 mm reduced APS by 48% in maize, 30% in SBM and 26% in maize–SBM. No interaction between screen size and microbial phytase on phytate degradation was observed, but the interaction between microbial phytase and incubation time was significant (P<0.001). This was because microbial phytase reduced phytate P by 88% in maize, 84% in maize–SBM and 75% in SBM after 2 h of incubation (P<0.05), whereas the reduction of phytate P was limited (<50%) in the feeds, even after 24 h when no microbial phytase was added. The exponential decay model was fitted to the feeds with microbial phytase to analyse the effect of screen size and feed on microbial phytase efficacy on phytate degradation. The interaction between screen size and feed affected the relative phytate degradation rate (R_d) of microbial phytase as well as the time to decrease 50% of the phytate P (t1/2) (P<0.001). Thus, changing from 3 to 1 mm screen size increased R_d by 22 and 10%/h and shortened t1/2 by 0.4 and 0.2 h in maize and maize–SBM, respectively (P<0.05), but not in SBM. Moreover, the screen size effect was more pronounced in maize and maize–SBM compared with SBM as a higher phytate degradation rate constant (K_d) and R_d, and a shorter t1/2 was observed in maize compared with SBM in all screen sizes (P<0.05). However, a higher amount of degraded phytate was achieved in SBM than in maize because of the higher initial phytate P content in SBM. In conclusion, reducing screen size from 3 to 1 mm increased K_d and R_d and decreased t1/2 in maize and maize–SBM with microbial phytase. The positive effect of grinding on improving microbial phytase efficacy, which was expressed as K_d, R_d and t1/2, was greater in maize than in SBM.