基于渐进核图割的SAR图像自动分割

合成孔径雷达(Synthetic Aperture Radar,SAR)图像是遥感目标检测与分割等研究的重要数据源。提出了一种渐进核图割分割方法,该方法通过迭代进行二类聚类分割,自动实现合成孔径雷达SAR图像中多目标的分割。实验结果表明,该方法能够有效地实现复杂场景SAR图像的多目标分割。     

Improving confidence in (Q)SAR predictions under Canada’s Chemicals Management Plan – a chemical space approach$

Abstract

One of the key challenges of Canada’s Chemicals Management Plan (CMP) is assessing chemicals with limited/no empirical hazard data for their risk to human health. In some instances, these chemicals have not been tested broadly for their toxicological potency; as such, limited information exists on their potential to induce human health effects following exposure. Although (quantitative) structure activity relationship ((Q)SAR) models are able to generate predictions to address data gaps for certain toxicological endpoints, the confidence in predictions also needs to be addressed. One way to address this issue is to apply a chemical space approach. This approach uses international toxicological databases, for example, those available in the Organisation for Economic Co-operation and Development (OECD) QSAR Toolbox. The approach,assesses a model’s ability to predict the potential hazards of chemicals that have limited hazard data that require assessment under the CMP when compared to a larger, data-rich chemical space that is structurally similar to chemicals of interest. This evaluation of a model’s predictive ability makes (Q)SAR analysis more transparent and increases confidence in the application of these predictions in a risk-assessment context. Using this approach, predictions for such chemicals obtained from four (Q)SAR models were successfully classified into high, medium and low confidence levels to better inform their use in decision-making.     

Reliability of single aliquot regenerative protocol (SAR) for dose estimation in quartz at different burial temperatures: A simulation study

The single aliquot regenerative protocol (SAR) is a well-established technique for estimating naturally acquired radiation doses in quartz. This simulation work examines the reliability of SAR protocol for samples which experienced different ambient temperatures in nature in the range of −10 to 40 °C. The contribution of various experimental variables used in SAR protocols to the accuracy and precision of the method is simulated for different ambient temperatures. Specifically the effects of paleo-dose, test dose, pre-heating temperature and cut-heat temperature on the accuracy of equivalent dose (ED) estimation are simulated by using random combinations of the concentrations of traps and centers using a previously published comprehensive quartz model. The findings suggest that the ambient temperature has a significant bearing on the reliability of natural dose estimation using SAR protocol, especially for ambient temperatures above 0 °C. The main source of these inaccuracies seems to be thermal sensitization of the quartz samples caused by the well-known thermal transfer of holes between luminescence centers in quartz. The simulations suggest that most of this inaccuracy in the dose estimation can be removed by delivering the laboratory doses in pulses (pulsed irradiation procedures).     

紫杉醇构效关系研究新进展

综述了近年来在紫杉醇类似物构效研究中的最新进展,按照紫杉醇的A,B, C,D环修饰的顺序总结了新得到的40余种紫杉醇类似物结构与其生物活性之间的关系。     

Synthesis of Cytotoxic Sinapyl Alcohol Derivatives fromLigularia nelumbifolia

Total synthesis of two cytotoxic natural products, nelumol A(1) and nelumal A(2), were carried out by two different paths. 4-O-Benzyl substitute analogues 26 and 27, as well as the 4-O-(2-methyl-butenyl) derivatives 29 and 30 were also synthesized for a SAR invesigation. 1 and 2 were also measured on different tumor cell line.     

Quantitative Studies on Structure－Activity Relationships （QSAR） of Cytokinin－Active Phenyl Urea Derivatives（PUD）

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Synthesis and Anticancer Activity Evaluation of 5-[2-Chloro-3-(4-nitrophenyl)-2-propenylidene]-4-thiazolidinones

A series of novel 5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-thiazolidinones (Ciminalum–thiazolidinone hybrid molecules) have been synthesized. Anticancer activity screening toward the NCI60 cell lines panel, gastric cancer (AGS), human colon cancer (DLD-1), and breast cancer (MCF-7 and MDA-MB-231) cell lines allowed the identification of 3-{5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-4-oxo-2-thioxothiazolidin-3-yl}propanoic acid (2h) with the highest level of antimitotic activity with mean GI₅₀/TGI values of 1.57/13.3 μM and a certain sensitivity profile against leukemia (MOLT-4, SR), colon cancer (SW-620), CNS cancer (SF-539), melanoma (SK-MEL-5), gastric cancer (AGS), human colon cancer (DLD-1), and breast cancers (MCF-7 and MDA-MB-231) cell lines. The hit compounds 2f, 2i, 2j, and 2h have been found to have low toxicity toward normal human blood lymphocytes and a fairly wide therapeutic range. The significant role of the 2-chloro-3-(4-nitrophenyl)prop-2-enylidene (Ciminalum) substituent in the 5 position and the substituent’s nature in the position 3 of core heterocycle in the anticancer cytotoxicity levels of 4-thiazolidinone derivatives have been established     

New synthetic quinaldine conjugates: Assessment of their anti-cholinesterase,anti-tyrosinase and cytotoxic activities,and molecular docking analysis

Despite all the progress made to enrich the existing bank of drugs used to treat and cure Alzheimer and cancer patients, there is still a need to research and develop new bioactive candidates with superior efficacy but minimal side effects. In this context, a new series of anti-butyrylcholinesterase (anti-BChE), anti-tyrosinase and cytotoxic succinimide linked quinaldine conjugates 3a-i was designed and synthesized starting from 8-hydroxyquinaldine. The condensation of quinoleine-hydrazide 2 with electrophilic species such as aromatic and nonaromatic anhydrides provided the new compounds 3a-i. These synthesized heterocycles were characterized by spectroscopic means (¹H NMR, ¹³C NMR and ESI-HRMS). Their anti-butyrylcholinesterase, anti-tyrosinase and cytotoxic (cervical cancer cell (HeLa) and lung cancer cell (A549)) activities have been evaluated in vitro. Compounds 3e and 3 g were found to be more anti-BChE than Galanthamine. Compounds 3d, 3e and 3 g exerted better anti-tyrosinase activity than kojic acid. Also, 3a, 3f and 3 g showed interesting cytotoxic potential towards HeLa cell lines. These results were supported by the molecular docking analysis (structure–activity relationship (SAR)) to estimate and discuss possible interactions between these derivatives and active sites of proteins butyrylcholinesterase (PDB: 4B0P), tyrosinase (PDB: 2Y9X) and cytotoxic (topoisomerase IIα enzyme (PDB: 5GWK)).     

Outliers in SAR and QSAR: 2. Is a flexible binding site a possible source of outliers?

Structure-activity relationship (SAR) and/or quantitative structure-activity relationship (QSAR) studies play an important role in a lead optimization of drug discovery research. When there is a lack of ligand-bound protein structural information, one of the assumptions in SAR and QSAR studies is that similar analogs bind to the same binding site in a similar binding mode. In such studies, outliers have often been observed, especially in QSAR. However, most of these studies have focused their attention on the development of QSAR and left outliers unattended. We searched ligand-bound X-ray crystal structures from the protein structure database to find evidences that could indicate a possible source of outliers in SAR or QSAR. Our results showed the possibility of conformational changes in a flexible binding site as one possible source of outliers. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.