“Parallel factor analysis of multi-excitation ultraviolet resonance Raman spectra for protein secondary structure determination”

Protein secondary structural analysis is important for understanding the relationship between protein structure and function, or more importantly how changes in structure relate to loss of function. The structurally sensitive protein vibrational modes (amide I, II, III and S) in deep-ultraviolet resonance Raman (DUVRR) spectra resulting from the backbone C–O and N–H vibrations make DUVRR a potentially powerful tool for studying secondary structure changes. Experimental studies reveal that the position and intensity of the four amide modes in DUVRR spectra of proteins are largely correlated with the varying fractions of α-helix, β-sheet and disordered structural content of proteins. Employing multivariate calibration methods and DUVRR spectra of globular proteins with varying structural compositions, the secondary structure of a protein with unknown structure can be predicted. A disadvantage of multivariate calibration methods is the requirement of known concentration or spectral profiles. Second-order curve resolution methods, such as parallel factor analysis (PARAFAC), do not have such a requirement due to the “second-order advantage.” An exceptional feature of DUVRR spectroscopy is that DUVRR spectra are linearly dependent on both excitation wavelength and secondary structure composition. Thus, higher order data can be created by combining protein DUVRR spectra of several proteins collected at multiple excitation wavelengths to give multi-excitation ultraviolet resonance Raman data (ME-UVRR). PARAFAC has been used to analyze ME-UVRR data of nine proteins to resolve the pure spectral, excitation and compositional profiles. A three factor model with non-negativity constraints produced three unique factors that were correlated with the relative abundance of helical, β-sheet and poly-proline II dihedral angles. This is the first empirical evidence that the typically resolved “disordered” spectrum represents the better defined poly-proline II type structure.     

Detecting changes in arabidopsis cell wall composition using time‐of‐flight secondary ion mass spectrometry

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) was previously used to characterize lignocellulosic materials, including woody biomass. ToF‐SIMS can acquire both rapid spectral and spatial information about a sample's surface composition. In the present study, ToF‐SIMS was used to characterize the cell walls of stem tissue from the plant model organism, Arabidopsis thaliana. Using principal component analyses, ToF‐SIMS spectra from A. thaliana wild‐type (Col‐0), cellulose mutant (irx3), and lignin mutant (fah1) stem tissues were distinguished using ToF‐SIMS peaks annotated for wood‐derived lignocellulose, where spectra from the irx3 and fah1 were characterized by comparatively low polysaccharide and syringyl lignin content, respectively. Spatial analyses using ToF‐SIMS imaging furthermore differentiated interfascicular fiber and xylem vessels based on differences in the lignin content of corresponding cell walls. These new data support the applicability of ToF‐SIMS peak annotations based on woody biomass for herbaceous plants, including model plant systems like arabidopsis. Copyright © 2015 John Wiley & Sons, Ltd.     

Experimental study on the fiber pull-out of composites using digital gradient sensing technique

A method to measure the stress field at the fiber tip in the fiber pull out test was proposed by using a digital gradient sensing technique. First, the principle of digital gradient sensing is introduced, and the non-contact optical system of digital gradient sensing developed. Then, a fiber reinforced composite model specimen, where a nail was inserted in epoxy resin to act as a fiber, was performed, and a pull out test was conducted on the specimen using the digital gradient sensing technique. Finally, the angular deflections contour at the fiber tip was obtained, and the stress intensity factor was extracted from the angular deflections. The results show that the stress intensity factor at the fiber tip extracted from the angular deflections agreed with the results calculated by the finite element method.     

Screening of drugs of abuse and toxic compounds in human whole blood using online solid‐phase extraction and high‐performance liquid chromatography with time‐of‐flight mass spectrometry

A novel method for the screening of 151 drugs of abuse and toxic compounds in human whole blood has been developed and validated by online solid‐phase extraction with liquid chromatography coupled to time‐of‐flight mass spectrometry. Analytes were extracted and separated by using a fully automated online solid‐phase extraction liquid chromatography system with total chromatographic run time of 26 min. Time‐of‐flight mass spectrometry screening of 151 drugs of abuse and toxic compounds was performed in a full‐scan (m/z 50–800) mode using an MS^E acquisition of molecular ions and fragment ions data at two collision energies (one was 6 eV and another one was in the range of 5–45 eV). The compounds were identified based on retention times and exact mass of molecular ions and fragment ions. The limit of detection ranged from 1 to 100 ng/mL and the recovery of the method ranged from 6.3 to 163.5%. This method is proved to be a valuable screening method allowing fast and specific identification of drugs in human whole blood.     

Screening anti‐tumor compounds from Ligusticum wallichii using cell membrane chromatography combined with high‐performance liquid chromatography and mass spectrometry

Tyrosine 367 Cysteine‐fibroblast growth factor receptor 4 cell membrane chromatography combined with high‐performance liquid chromatography and mass spectrometry was developed. Tyrosine 367 Cysteine‐HEK293 cells were used as the cell membrane stationary phase. The specificity and reproducibility of the cell membrane chromatography was evaluated using 1‐tert‐butyl‐3‐{2‐[4‐(diethylamino)butylamino]‐6‐(3,5‐dimethoxyphenyl)pyrido[2,3‐d]pyrimidin‐7‐yl}urea, nimodipine and dexamethasone acetate. Then, anti‐tumor components acting on Tyrosine 367 Cysteine‐fibroblast growth factor receptor 4 were screened and identified from extracts of Ligusticum wallichii. Components from the extract were retained on the cell membrane chromatographic column. The retained fraction was directly eluted into high‐performance liquid chromatography with mass spectrometry system for separation and identification. Finally, Levistolide A was identified as an active component from Ligusticum wallichii extracts. The 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐tetrazolium bromide‐formazan colorimetric assay revealed that Levistolide A inhibits proliferation of overexpressing the mutated receptor cells with dose‐dependent manner. Phosphorylation of fibroblast growth factor receptor 4 was also decrease under Levistolide A treatment. Flex dock simulation verified that Levistolide A could bind with the tyrosine kinase domain of fibroblast growth factor receptor 4. Therefore, Levistolide A screened by the cell membrane chromatography combined with high‐performance liquid chromatography and mass spectrometry can arrest cell growth. In conclusion, the two‐dimensional high‐performance liquid chromatography method can screen and identify potential anti‐tumor ingredients that specifically act on the tyrosine kinase domain of the mutated fibroblast growth factor receptor 4.     

高中学业水平考试试题难度模型建构*

利用主成分分析方法厘清试题难度影响因素之间的关系,进而从问题表征、问题解决和结果输出等3个维度上建立了影响高中学业水平考试试题难度的主要因素。通过编写高中学业水平考试测试题进行实证研究,建立影响因素常见呈现类型的难易赋值规则。选用机器学习的线性回归方法建构试题难度分析模型,并使用高考化学江苏卷部分试题的实测难度数据进行校验,模型难度预测值和高考难度实测值具有较好的拟合度,表明模型具有较好的应用价值和推广意义。     

Enhanced stability designs of cell membrane chromatography for screening drug leads

Cell membrane chromatography is an effective method for screening bioactive components acting on specific receptors in complex systems, which maintains the biological activity of the membrane receptors and improves screening efficiency. However, traditional cell membrane chromatography suffers from poor stability, resulting in a limited life span and low reproducibility, greatly limiting the application of this method. To address this problem, cyanuric chloride-decorated silica gel was used for the covalent immobilization of the cell membranes. Cyanuric chloride reacts with amino groups on the cell membranes and membrane receptors to form covalent bonds. In this way, the cell membranes are not easy to fall off. The column life of the cyanuric chloride-decorated epidermal growth factor receptor/cell membrane chromatography column was extended to more than 8 days, whereas the column life of the normal cell membrane chromatography column dropped sharply in the first 3 days. A cyanuric chloride-decorated epidermal growth factor receptor/cell membrane chromatography online HPLC-IT-TOF-MSn system was applied for screening drug leads from Trifolium pratense L. One potential drug lead, formononetin, which acts on the epidermal growth factor receptor, was screened. Our strategy of covalently immobilizing cell membrane receptors also improved the stability of cell membrane chromatography.     

治疗非小细胞肺癌脑转新药:Zorifertinib

新药Zorifertinib是阿斯利康公司针对非小细胞肺癌(NSCLC)脑转研发的一种表皮生长因子酪氨酸激酶抑制剂(EGFR-TKI),对EGFR 19外显子缺失和EGFR 21外显子L858R突变有高选择性和高抑制性,相较于其他EGFR-TKIs的突出优势是具有优秀的血脑屏障渗透性。临床研究表明Zorifertinib可以在脑内达到等同血浆的药物浓度,有效抑制脑内肿瘤生长,减少脑内肿瘤面积,并且预防脑内肿瘤形成。本文将对该新药的作用机制、研发历程、药代动力学、临床研究和安全性进行综述,为广大研究者以及今后的临床应用提供参考。     

Electrospinning of Biomaterials for Vascular Regeneration

Cardiovascular diseases have been the leading cause of morbidity and mortality in the world recently. With the growing aging population accompanied by chronic diseases, such as uremia and diabetes, there is an increasing clinical demand for vascular grafts with proper performance. Although some achievements have been made in the development of tissue-engineered vascular grafts composed of natural and synthetic polymeric materials or decellularized vessels, clinical applications with a diameter of less than 6 mm are still principally derived from autografts, such as autologous saphenous veins. Many challenges remain in anti-thrombosis, rapid endothelialization, modulating the inflammatory response and inhibition of intimal hyperplasia and calcification. In the review, recent progress in the electrospinning of biodegradable polymers for vascular regeneration are summarized, especially from the view of biomechanical factors. Hybrid vascular grafts consisting of natural and synthetic polymers with multicomponent, di-or tri-layers are focused in order to provide novel experiences in biomaterials for applications in this field.     

A novel aptasensor based on 3D-inorganic hybrid composite as immobilized substrate for sensitive detection of platelet-derived growth factor

A novel electrochemical detection approach for platelet-derived growth factor(PDGF) via "sandwich"structure is reported in this paper. 3D-4MgCO_3 Mg(OH)_2 4H_2O-Au NPs inorganic hybrid composite was utilized as immobilized substrate for sensitive PDGF detection and Pt-Au bimetallic nanoparticles were labelled on PDGF aptamer to indirectly detect PDGF for the first time. The proposed aptasensor exhibited a high catalytic efficiency towards reduction of H_2O_2, hence the sensitive detection of PDGF was achieved.Results showed that the aptasensor exhibited excellent linear response to PDGF, in the range of 0.1 pg/m L–10 ng/m L(4 fmol/L–400 pmol/L), with detection limit of 0.03 pg/m L(1.2 fmol/L).