Effect of acquisition time and chemical fat suppression on meningeal enhancement on MR imaging in dogs

Our purpose was to characterize meningeal gadolinium enhancement on magnetic resonance (MR) imaging in dogs with inflammatory and neoplastic diseases, and to assess interobserver variability and the impact of delayed acquisition and chemical fat saturation on its conspicuity. Transverse T1-weighted FLAIR images were acquired prior to, and immediately following gadolinium injection (T0), and at 5 (T5) and 15-20 min delay (TD), with and without fat suppression, in 155 consecutive dogs imaged for suspected brain disease. The agreement on meningeal enhancement was globally substantial (kappa = 0.61) and the likelihood of obtaining a definite diagnosis was significantly increased with the use of fat suppression (P < or = 0.004). Meningeal enhancement was judged definitively present by consensus in 46 of 155 (30%) dogs. Of these, meningeal enhancement was characterized qualitatively and quantitatively in 30 dogs with a clinical diagnosis (18 inflammatory, 11 neoplastic, 1 infarct), and image sequences were compared. Meningeal enhancement was more often diffuse and leptomeningeal in animals with inflammation versus neoplasia (50% vs. 42%, and 69% vs. 48%, respectively), but significant associations were not found. Meningeal thickness and contrast ratio were higher with neoplasia (P < or = 0.02), but results did not vary significantly between series for either group. Yet, images with fat suppression were most useful 50% of the time for definite diagnosis and/or characterization of meningeal enhancement. While delayed image acquisition following gadolinium injection does not improve characterization of meningeal enhancement in dogs, fat suppression is beneficial qualitatively.     

应用抑制消减杂交技术克隆鼻咽癌转移调控基因

目的：分离并鉴定高低转移表型不同的人鼻咽癌细胞株差异表达cDNA序列,了解鼻咽癌转移抑制基因或具有抑制活性的核苷酸序列。方法：以具有高低转移潜能不同的人鼻咽癌细胞株为研究对象,应用抑制消减杂交技术（suppression subtractive hybridization,SSH）和T／A克隆法构建差异表达cDNA消减文库,对差异表达的cDNA进行测序和生物信息学分析。结果：成功构建人鼻咽癌细胞克隆株差异表达cDNA消减文库,从随机测序10个克隆中获得6个在低转移鼻咽癌细胞株中高表达cDNA序列,它们都与已知的人类基因片段具有高度同源性。结论：应用抑制消减杂交技术,从一对具有高低转移表型差异的鼻咽癌细胞株中获得6条可能与肿瘤转移抑制相关的cDNA序列,它们可能在维持肿瘤细胞的稳定和抑制肿瘤转移中起重要作用。     

香蕉果实采后抑制差减文库的构建与鉴定

抑制差减杂交技术(suppression subtracfive hybridization,SSH),是抑制PCR与差减杂交技术相结合而产生的。其优点是在差减杂交过程中使不同丰度cDNA的拷贝数差异趋于均衡,因此不同丰度的差异表达基因都能得到有效克隆,能有效分离低丰度的差异表达基因,避免了表达序列标签分析中高丰度基因重复测序的缺点。因此SSH技术被应用于植物差异表达基因的分离。香蕉果实采后成熟过程中发生一系列复杂的生理变化,这些变化涉及到许多基因的表达。为了研究香蕉果实采后与采前在基因表达上的差异,我们首次采用抑制缩减文库的方法,以分离香蕉果实在采后表达的基因。以采后0h的香蕉果实cDNA为驱动子,对香蕉果实采后48h果实cDNA为待测子,进行抑制缩减杂交,抑制缩减杂交产物与pGEM—TEasy Vecter连接,转化E．coli DH5α,构建了抑制缩减文库。该文库共包含312个克隆,采用PCR方法对文库进行了重组子的鉴定,共有302个重组子。该文库的构建成功为深入研究香蕉果实采后基因的表达奠定了基础,为研究香蕉果实采后成熟的分子生物学机理提供了一个新的思路。     

The pulp and paper properties of Sirex noctilio infested and fire-damagedthermomechanically pulped,South African grown Pinus patula

Pinus patula is the softwood species most extensively planted in South Africa. However, large portions of these plantings are under threat from Sirex noctilio infestation and occasional forest fires. In this exploratory investigation, the effects of tree age, Sirex noctilio infestation and fire damage to wood from Pinus patula trees on their pulp and paper properties were evaluated. Pulp was produced using the thermomechanical pulping (TMP) process. The energy consumption required to pulp the different pulpwood materials was determined. Pulps were beaten for five different time periods to investigate the development of the fibre properties in response to increasing energy input. Paper properties such as burst, tear strength and breaking length were determined on handsheets manufactured from unbeaten and beaten pulps. Box and line plots and canonical variate analysis biplots were used to statistically analyse the data. It was found that the burst strength of paper produced from healthy trees was significantly higher than that from sirex-infested or fire damaged (burnt) trees. Similarly, the tear strength of paper from healthy and burnt trees was significantly better than from sirex-infested or young trees. No significant differences in breaking length were evident between the pulpwood materials and an increase in beating time did not lead to any improvements. From this study it can be concluded that wood from dead or dying, sirex-infested and young trees produced paper with consistently lower strength properties compared to wood obtained from healthy 12-year-old trees.     

Oxytocin Cells in the Supraoptic Nucleus Receive Excitatory Synaptic Inputs from the Contralateral Supraoptic and Paraventricular Nuclei in the Lactating Rat

The present experiments were undertaken to examine whether oxytocin cells in the supraoptic nucleus receive synaptic inputs from the contralateral supraoptic nucleus or paraventricular nucleus. Using urethane-anesthetized lactating rats, extracellular action potentials were recorded from single oxytocin or vasopressin cells in the supraoptic nucleus. Electrical stimulation was applied to the contralateral supraoptic nucleus or paraventricular nucleus, and responses of oxytocin or vasopressin cells were analyzed by peri-stimulus time histogram or by change in firing rate of oxytocin or vasopressin cells. Electrical stimulation of the contralateral supraoptic nucleus or paraventricular nucleus did not cause antidromic excitation in oxytocin or vasopressin cells but caused orthodromic responses. Although analysis by peri-stimulus time histogram showed that electrical stimulation of the contralateral supraoptic nucleus or paraventricular nucleus caused orthodromic excitation in both oxytocin and vasopressin cells, the proportion of excited oxytocin cells was greater than that of vasopressin cells. Train stimulation applied to the contralateral supraoptic nucleus or paraventricular nucleus at 10 Hz increased firing rates of oxytocin cells and decreased those of vasopressin cells. The results of the present experiments suggest that oxytocin cells in the supraoptic nucleus receive mainly excitatory synaptic inputs from the contralateral supraoptic nucleus and paraventricular nucleus. Receipt these synaptic inputs to oxytocin cells may contribute to the synchronized activation of oxytocin cells during the milk ejection reflex.     

城乡流动、社会排斥与城市包容:珠三角代耕农的社会情绪及化解策略

20世纪70年代末以来,改革开放带来的社会变迁及城镇化发展,导致珠三角地区形成一个特殊群体"代耕农"。其主要分布在城郊、城乡结合部及城中村,为珠三角城乡经济发展有历史贡献,却因政策变化、经济发展等历史与现实的多重原因,沦为具有"双重边缘性"的弱势群体并引发系列社会问题。随着城市化进程的推进,城市问题不再是单纯的城市区域性问题。城市问题俨然已逐步上升为事关城市区域联动发展的系统性议题,城乡流动、城乡排斥、城乡融合、城市包容等诸多议题愈来愈被纳入城市管理研究之中。代耕农问题的产生,在本质上与城市化有着密切关联,代耕农贬抑的社会情绪反过来对于城市管理、城市发展又有着巨大不良影响,代耕农问题也是城市问题。从代耕农与城市互动视角,探讨代耕农社会情绪的产生逻辑,分析代耕农社会情绪对城市发展的不良影响,提出代耕农社会情绪的化解策略。     

城市堤防漫决模拟——以哈尔滨市松北区为例

洪水灾害是我国城市中发生较为频繁且破坏性较大的自然灾害之一,阻碍城市可持续发展。针对已有研究中设定堤防一点漫决堤情景模拟方法较为单一的缺点,提出多点堤防漫决堤洪水演进方法。以哈尔滨市松北区为实证研究区,以水动力学方法为基础,以不规则网格为洪水灾害数值模型骨架,以一、二维非恒定流为洪水灾害数值模型控制方程,综合构建堤防多点同时漫决堤情景下洪水演进模型,并对研究区不同洪水频率情景进行模拟。研究结果表明,该方法可以较好地模拟多点破堤情景下,即0.5%频率、1%频率、2%频率的洪水演进及叠加效果,其中当破堤1 h后研究区最大淹没水深可达3 m以上,同时利用GIS空间可视化技术对研究结果进行可视化表达,为防洪规划设计提供决策依据。     

Growth and weed suppression ability of common and new cover crops in Germany

Cover crops have a wide-ranging influence on the agroecosystem and create multiple benefits for farmers. A major benefit of cover crops is the suppression of weeds during fall and winter, which can help to reduce soil tillage and herbicide use. However, only a small number of cover crop species are currently grown in Germany. To enlarge this number, four new cover crop species including tartary buckwheat, forage radish, red oat and grain amaranth were tested in comparison with common cover crop species such as white mustard, oilseed radish and phacelia. Emergence, soil coverage, dry matter production and weed suppression ability was assessed for all cover crop species. White mustard emerged faster than all other cover crops and produced the highest amount of shoot dry matter at both locations in southwest Germany twelve weeks after planting (WAP). Oilseed radish was the only cover crop that reduced the weed dry matter in all experiments eight WAP. Phacelia was able to reduce weed density by 77% at Meiereihof twelve WAP. Tartary buckwheat offered the highest soil coverage four WAP, produced the greatest shoot dry matter eight WAP and reduced weed dry matter by more than 96% at Meiereihof and Ihinger Hof twelve WAP. Forage radish produced the highest root dry matter and reduced spring weed density by more than 81% in all experiments. Red oat and grain amaranth emerged slowly, produced less biomass than other cover crops and did not suppress weed growth. The results show that tartary buckwheat and forage radish are well suited as new cover crops in Germany due to their fast growth and good weed suppression ability.     

MAGNETIC RESONANCE IMAGING OF THE CANINE OPTIC NERVE

We describe the magnetic resonance (MR) imaging aspects of normal canine optic nerve, the diameter of the optic nerve as measured on MR images, and optimal MR sequences for the evaluation of the optic nerve using a 0.2 T MR unit. Three millimeter contiguous slides of the normal canine orbital region were acquired in transverse and dorsal oblique planes using a variety of tissue weighting sequences. It was apparent that detailed anatomic assessment of the optic nerve can be performed with low‐field MR imaging, but none of the sequences provided unequivocal superior image quality of the optic nerve. The mean diameter of the optic nerve sheath complex was 3.7 mm and of the optic nerve 1.7 mm. The intraorbital and intracanalicular parts of the optic nerve are consistently visible and differentiation between the optic nerve and optic nerve sheath complex is possible using low‐field MR systems.