Hypoxia-ischemia induces a rapid elevation of ubiquitin conjugate levels and ubiquitin immunoreactivity in the immature rat brain

Postnatal rats at 7 and 21 days of age were subjected to unilateral hypoxia-ischemia (H/I) by right carotid artery ligation followed by 1.5 to 2 hours of hypoxia (8% oxygen). Brains were frozen at specific intervals of recovery from 0 to 24 hours. Western blots of samples of right and left forebrain were immunodeveloped with a monoclonal antibody specific for ubiquitin, RHUb1. An elevation of ubiquitin conjugate levels in the right compared with the left forebrain of 7-day-old animals was detectable immediately following H/I and increased by close to 60% of control level within 1 hour of recovery. The conjugate immunoreactivity remained at this level for 6 hours but had declined to control levels by 24 hours of recovery. No such increase was observed in response to hypoxia alone. Similar changes were observed in samples from the 21-day-old rat brain. However, the elevation of ubiquitin conjugate levels was of slower onset and persisted longer than observed for the 7-day-old animals. Immunocytochemical studies of brain fixed by immersion in formaldehyde/acetone/methanol showed that ubiquitin-like immunoreactivity was increased in the right, but not left, cerebral cortex and hippocampus of animals subjected to H/I. The data suggest that elevated ubiquitination may represent a neuroprotective response to H/I.     

Influence of extrinsic and intrinsic parameters onto the formation of surface relief gratings in polar azo molecular glasses

Polar azo derivatives exhibiting stable glass-forming properties displayed efficient migration properties as thin films when subjected to interferential illumination, and formed time-stable and rewritable surface relief gratings as high as the initial film thickness. Intrinsic (film thickness, structure bulkiness) as well as extrinsic (laser fluence and polarization) parameters dramatically influenced the rate of the relief growth as well as the maximum relief amplitude. The superimposition of +45°/−45°-polarized beams unexpectedly conducted to a diffraction efficiency ten times as high as the combination of two p/p (parallel to the incident plane) polarized beams. The introduction of bulky anthryl Diels-Alder substituents showed net increase in the modulation amplitude due to the creation of large free volume around each azo unit, facilitating the azo migration within the less densely packed material.     

Circulating Tumor Cells (CTC) and Cell-Free DNA (cfDNA) Workshop 2016: Scientific Opportunities and Logistics for Cancer Clinical Trial Incorporation

Despite the identification of circulating tumor cells (CTCs) and cell-free DNA (cfDNA) as potential blood-based biomarkers capable of providing prognostic and predictive information in cancer, they have not been incorporated into routine clinical practice. This resistance is due in part to technological limitations hampering CTC and cfDNA analysis, as well as a limited understanding of precisely how to interpret emergent biomarkers across various disease stages and tumor types. In recognition of these challenges, a group of researchers and clinicians focused on blood-based biomarker development met at the Canadian Cancer Trials Group (CCTG) Spring Meeting in Toronto, Canada on 29 April 2016 for a workshop discussing novel CTC/cfDNA technologies, interpretation of data obtained from CTCs versus cfDNA, challenges regarding disease evolution and heterogeneity, and logistical considerations for incorporation of CTCs/cfDNA into clinical trials, and ultimately into routine clinical use. The objectives of this workshop included discussion of the current barriers to clinical implementation and recent progress made in the field, as well as fueling meaningful collaborations and partnerships between researchers and clinicians. We anticipate that the considerations highlighted at this workshop will lead to advances in both basic and translational research and will ultimately impact patient management strategies and patient outcomes.     

Behavior of Paramagnetic Iron during the Thermal Transformations of Kaolinite

Kaolinites with various degrees of structural order and iron content were heated and subsequently analyzed via electron paramagnetic resonance. Iron was present in two different states in the heated materials, either as dilute structural Fe³⁺ ions or in concentrated Fe³⁺ phases. During metakaolinization, the environment of dilute Fe³⁺ ions changed, following modifications of the Al³⁺ coordination, and the Fe³⁺ concentration increased. With the breakdown of metakaolinite, the diffusion of Fe³⁺ ions induced their exsolution in superparamagnetic iron-rich domains (Fe³⁺ clusters in γ-Al₂O₃ and/or Fe³⁺ oxide nanophases), which produced a decrease in the dilute Fe³⁺ concentration. The subsequent breakdown of γ-Al₂O₃ and the formation of mullite made the dilute Fe³⁺ concentration increase again, because of the incorporation of Fe³⁺ ions in the mullite structure.     

Arabidopsis thaliana Plants with Different Levels of Aliphatic- and Indolyl-Glucosinolates Affect Host Selection and Performance of Bemisia tabaci

Generalist insects show reduced selectivity when subjected to similar, but not identical, host plant chemical signatures. Here, we produced transgenic Arabidopsis thaliana plants that over-express genes regulating the aliphatic- and indolyl- glucosinolates biosynthetic pathways with either a constitutive (CaMV 35S) or a phloem-specific promoter (AtSUC2). This allowed us to examine how exposure to high levels of aliphatic- or indolyl-glucosinolates in homogenous habitats (leaf cage apparatus containing two wild-type or two transgenic leaves) and heterogeneous habitats (leaf cage apparatus containing one wild-type and one transgenic leaf) affects host selection and performance of Bemsia tabaci, a generalist phloem-feeding insect. Data from homogenous habitats indicated that exposure to A. thaliana plants accumulating high levels of aliphatic- or indolyl-glucosinolates negatively affected the performance of both adult females and nymphs of B. tabaci. Data from heterogeneous habitats indicated that B. tabaci adult females selected for oviposition plants on which their offspring perform better (preference-performance relationship). However, the combinations of wild-type and transgenic plants in heterogeneous habitats increased the period of time until the first choice was made and led to increased movement rate on transgenic plants, and reduced fecundity on wild-type plants. Overall, our findings are consistent with the view that both performance and selectivity of B. tabaci decrease in heterogeneous habitats that contain plants with closely-related chemical signatures.     

Significant Decline in Galactomannan Signal during Storage of Clinical Serum Samples

Galactomannan (GM) is widely used for detection of invasive aspergillosis in high-risk haemato-oncology patients. Recent publications have reported a lack of repeatability of GM detection. The objective of this retrospective study was to assess the repeatability of GM levels during storage of clinical samples. In a GM screening strategy, positive sera were repeat tested as per manufacturer’s recommendations. Short-term (ST) storage of samples was at +4 °C while long-term (LT) storage was at −80 °C. Bronchoalveolar (BAL) fluid was also repeating tested after ST storage and LT storage. Wilcoxon Signed Ranks Test was employed to assess the repeatability of GM levels. In a subset of 14 GM positive sera, repeat testing was performed on both the original serum and ethylenediaminetetraacetic acid (EDTA) pre-treated sample. There was a significant reduction in GM signals on repeat testing following ST storage (median GM index: 0.65 vs. 0.19; p < 0.001) and LT storage (median GM index: 0.56 vs. 0.10; p < 0.001) of serum samples. Of samples that were initially GM positive, an average GM index reduction of 50% was seen, with approximately two-thirds becoming GM negative on repeat testing of the same sample. In contrast, GM signal loss was not seen on repeat testing of BAL fluid following ST or LT storage. When GM positive serum samples were repeat tested using EDTA pre-treated serum from the first step of the testing protocol, all samples remained GM positive. In contrast, when the same samples were repeat tested from the original collected serum, 9 samples (64%) became GM negative. The significant reduction in GM signals during ST and LT storage of serum samples has implications for clinical management. Although the reasons for GM decline are unknown, they occur prior to the EDTA pre-treatment stage, indicating that the time from phlebotomy to testing should be minimized. BAL fluid GM index values remain stable.     

The preparation of flat H–Si(111) surfaces in 40% NH4F revisited

The reasons why ideally flat H–Si(111) surface can be prepared by NH₄F etching are investigated from correlation between AFM observations and experimental conditions used for etching. It is shown that pitting may be completely suppressed if a one side polished wafer is immersed in an oxygen free solution. An analytical electrochemical study of the (111) and rough face of the same n-Si wafer is presented to yield insight into observations.     

Solid‐state NMR characterization of cyclomaltoheptaose (β‐cyclodextrin) polymers using high‐resolution magic angle spinning with gradients

Solid‐state nuclear magnetic resonance (NMR) techniques were used to characterize cyclomaltoheptaose (β‐cyclodextrin, β‐CD) polymers. These insoluble materials have been investigated by cross‐polarization magic angle spinning with dipolar decoupling (CP/MAS), magic angle spinning without dipolar decoupling (MAS), and high‐resolution magic angle spinning with gradients (HRMAS). These NMR spectra allow the assignment of the principal ¹H and ¹³C signals. The presence of two distinct components (cross‐linked β‐CD and polymerized epichlorohydrin) in the materials was clearly demonstrated. These polymers were used as sorbents and the resulting NMR spectra are presented and discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1288–1295, 2000     

切题知识原则简论

本文第一部分简论知识的切题性及语境、总体性属性、多维度属性与复杂性等影响认知的因素;第二部分简论一般性智能及二十世纪高等教育中学科专业化对切题性知识的肢解;第三部分分析二十世纪(高等)教育中影响切题知识获取的三个基本问题:知识分割与封闭式专业化、还原与分离、虚假合理性。     

术前口服依他昔布对妇科手术后病人自控镇痛的影响

目的: 观察妇科开腹手术患者术前给予依他昔布120 mg 对术后自控镇痛(PCA) 吗啡用量的影响及其副作用。方法: 随机选取全麻下接受妇科开腹全子宫(双附件) 切除患者40 例, 术前分别给予安慰剂或依他昔布120 mg 口服。在手术后观察24 h 患者PCA 吗啡用量, 同时记录患者的疼痛评分和满意度评分, 并观察不良反应。结果: 术后PCA 吗啡24h 消耗量在依他昔布组为9.4±7.6 mg, 显著低于安慰剂组15.7±8.9 mg。两组患者24 h 内对PCA 的按压次数依他昔布组也低于安慰剂组(P <0.05)。其中术后3、6、8 和12 h PCA 吗啡消耗量在两组间无显著差异。两组患者术后24 h 疼痛评分和对镇痛治疗的满意度也无差异。两组患者不良反应的发生率亦无差别。结论: 在妇科开腹手术患者术前应用依他昔布120 mg 可使患者术后PCA 吗啡消耗量降低, 且在术后12 h 后下降明显。未发现与依他昔布应用相关的副作用。