有机膨润土辛硫磷缓释剂的制备和释放研究

使用缓释剂是减少农药对环境污染的有效策略.为开发成本低廉且具有释放速度调节能力的农药缓释剂,以十六烷基三甲基氯化铵(HTMAC)为改性剂制备的有机膨润土作为辛硫磷的载体,制备辛硫磷缓释颗粒剂,分析在水中辛硫磷颗粒剂的释放行为.结果显示,HTMAC改性有机膨润土对辛硫磷具有良好的吸附性能,其吸附量最高可达0.966 g/g膨润土.有机膨润土极大延缓了辛硫磷的释放速率,控制季铵盐的用量可以在一定程度上调节辛硫磷的释放速率,50％辛硫磷活性成分从改性剂用量为50％、100％和150％可交换阳离子容量的有机膨润土颗粒剂的释放时间T50分别为普通颗粒剂的3.4倍、10.4倍和10.1倍.     

关于鳞状因子循环矩阵的非奇异性

对于复数域上的n阶方阵4，如果满足AR＝RA，则称A为鳞状因子循环矩阵，其中R为基本鳞状因子循环矩阵。文中给出了仅用鳞状因子循环矩阵的第一行元素及对角阵D中的常数dl，d2，…，dn就可判断其非奇异性的3种简便方法。     

Bradykinin and nerve growth factor release the capsaicin receptor from PtdIns(4,5)P2-mediated inhibition.

Tissue injury generates endogenous factors that heighten our sense of pain by increasing the response of sensory nerve endings to noxious stimuli. Bradykinin and nerve growth factor (NGF) are two such pro-algesic agents that activate G-protein-coupled (BK2) and tyrosine kinase (TrkA) receptors, respectively, to stimulate phospholipase C (PLC) signalling pathways in primary afferent neurons. How these actions produce sensitization to physical or chemical stimuli has not been elucidated at the molecular level. Here, we show that bradykinin- or NGF-mediated potentiation of thermal sensitivity in vivo requires expression of VR1, a heat-activated ion channel on sensory neurons. Diminution of plasma membrane phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) levels through antibody sequestration or PLC-mediated hydrolysis mimics the potentiating effects of bradykinin or NGF at the cellular level. Moreover, recruitment of PLC-gamma to TrkA is essential for NGF-mediated potentiation of channel activity, and biochemical studies suggest that VR1 associates with this complex. These studies delineate a biochemical mechanism through which bradykinin and NGF produce hypersensitivity and might explain how the activation of PLC signalling systems regulates other members of the TRP channel family.     

载有溶菌酶微球的凝胶埋植剂的释药特性

为实现生物大分子药物的体内长期缓释,将药物制成乳酸/羟基乙酸共聚物(PLGA)的微球,再将微球分散于甲基纤维素反向温敏凝胶骨架中,制成微球-温敏凝胶复合埋植剂.通过体外释放实验,考察复合体系对模型药物溶菌酶的控释效果;通过凝胶色谱和扫描电镜,考察单独的微球以及在复合体系中的微球降解过程,分析凝胶介质对微球降解特性的影响;采用Peppas经验式来描述释放机制.结果表明: 在微球-凝胶复合体系中,溶菌酶可平稳释放30 d以上,无突释;药物释放是由载体溶蚀和药物扩散作用共同控制的.     

域Zp上的置换因子循环矩阵的逆阵

利用多项式的快速算法,给出了求域Zp上的置换因子循环矩阵的逆阵及Moore—Penrose逆的快速算法,最后给出的数值例子证明了该算法的有效性,该算法不需要预先知道置换因子循环矩阵的奇异性．     

Antisera to a synthetic peptide of the sis viral oncogene product recognize human platelet-derived growth factor

It has recently been reported that the sequences of the sis oncogene of simian sarcoma virus (SSV) and of human platelet-derived growth factor (PDGF) are very similar, establishing the most solid link yet between the mitogenic actions of growth factors and the transforming proteins of retroviruses. To investigate molecular mechanisms of transformation I have produced antisera against synthetic peptides corresponding to segments of the protein sequences predicted by the nucleotide sequences of viral oncogenes. Applying this approach to the case of sis and PDGF, I report here the results of probing outdated human platelets with an antiserum directed against a synthetic peptide representing residues 139-155 of the predicted sequence of the SSV transforming protein, p28sis (ref. 3). I detected peptides of apparent molecular weights (MWs) 30,000 to 31,000 (30-31K) and 16-18K, which correspond to the apparent molecular weights of nonreduced and reduced PDGF. In addition, a peptide of MW 21,000 was detected in platelets and a protein of MW 56,000 was detected in SSV-infected marmoset cells.     

由Hadamard矩阵构造的码

由Hadamard矩阵构造的码称为Hadamard码.文章根据Hadamard矩阵,用不同的方法构造出新的0,1矩阵,以此为生成矩阵生成了一类特殊的码;研究它的一些性质,证明了二元码C(2n-2, n-1)是自正交码的充分必要条件是n≡4(mod8),以及二元码C(2n-2, n-1)是自正交码的充分必要条件是二元码C(2n-2, n-1)是自对偶码.     

亲水/疏水半互穿网凝胶对牛血清白蛋白的控制释放

以牛血清白蛋白为对象,研究了亲水/疏水(QPVPD/PAAc)半互穿网凝胶对牛血清白蛋白的吸附与释放过程.在吸附过程中,当溶液pH值在牛血清白蛋白等电点(4.7)附近时,凝胶对蛋白质的吸附值最大;而在释放过程中,pH=7的释放率远大于其它pH值时的释放率.实验表明凝胶结构对蛋白质吸附与释放有较大影响.随着疏水成分的增加,凝胶对牛血清白蛋白的释放速率变缓.     

Specific anti-tumor effect induced by attenuated Salmonella typhimurium vaccine expressing extracellular region of vascular endothelial growth factor receptor 2

The purposes of this research were to study the stable expression of exogenous gene encoding therapeutic protein in attenuated Salmonella typhimurium, observe the metabolism of oral gene vaccine carried by attenuated Salmonella typhimurium in BALB/c mouse, and investigate the feasibility of prevention and treatment of tumors by the recombinant bacteria. Recombinant plasmid pcDNA3.1 VEGFR2(n1-7) was transformed into competent attenuated Salmonella typhimurium SL3261 to develop oral DNA vaccine SL3261-pcDNA3.1 VEGFR2(n1-7). To observe whether the exogenous gene can be expressed in the recombinant bacteria, PCR was performed to amplify the CMV promoter of the eukaryotic expression vector as the proof of stable expression of exogenous protein; transmission elec- tron microscopy (TEM) was applied to observe the morphology of the recombinant bacteria to confirm that the exogenous gene has no impact on the growth of the bacteria, and then BALB/c mice were immunized with the gene vaccine. After inoculation of the gene vaccine, the recombinant bacteria SL3261 could be detected in the tissues such as small intestine, colon, liver and spleen. And then, mice in each group were challenged with tumor cells. The results of animal experiment showed that tumor growth of the mice in experimental group was inhibited and survival time of immunized mice was prolonged compared with control groups. A higher lymphocyte infiltration in tumors from animals treated with DNA vaccine was observed. Immunohistochemical analysis of tumor samples revealed an en- hanced accumulation of CD8 cytotoxic T lymphocytes, as well as an increase in CD4 cells in the tumors of animals treated with the oral gene vaccine compared to tumors from control group mice. Ultrastructure of the tumor tissue showed that tumor cells in the samples of the immunized mice were well-differentiated. Our research confirmed that the exogenous gene can be stably expressed in the attenuated Salmonella typhimurium and has no impact on the growth of the recombinant bacteria; the exogenous gene can de delivered to the host by attenuated Salmonella typhimurium to produce anti-tumor effect with no obvious cytotoxity to the host. In this study, it is established that attenuated Salmonella typhimurium could be used as a vector for oral gene vaccine, and our study provided a theoretical basis for the body distribution and the metabolism of the recombinant bacteria. This strategy may provide a simple, safe and effective way for the prevention and treatment of tumors.     

神经生长因子

概述了神经生长因子的分子结构及作用机制，综述了神经生长因子的生理功能，神经生长因子不仅对神经细胞的存活，生长发育，分化，再生和功能维持起调控作用。同时也能诱导细胞凋亡。     

晶种辅助法控制合成CdS纳米棒

本论文以CS2为硫源．首先在十六烷基三甲基溴化铵(CTAB)胶束中制备CdS纳米棒品种．然后利用晶种辅助法实现了不同长径比的CdS纳米棒制备。实验结果表明晶种辅助生长法能否成叻与晶种在反应体系中溶解特性有很大关系。     

Vaccinia virus encodes a polypeptide homologous to epidermal growth factor and transforming growth factor

Epidermal growth factor (EGF) and transforming growth factor type I (TGF) are polypeptides of 53 and 50 amino acid residues, respectively. Both bind to EGF receptor, a 1,200-residue transmembranous glycoprotein, leading to phosphorylation of the receptor, enhancement of its tyrosine-specific kinase activity and ultimately to stimulation of cell growth. We report here that a 140-residue polypeptide encoded by one of the early genes of vaccinia virus (VV) is related closely to EGF and TGF. The presence of putative signal and transmembranous sequences further suggests that the viral protein might be an integral membrane protein, but that, as in the case of EGF itself, the membrane-associated form may be the precursor of a soluble growth factor. Production of EGF-like growth factors by virally infected cells could account for the proliferative diseases associated with members of the poxvirus family such as Shope fibroma virus, Yaba tumour virus, and molluscum contagiosum virus (MCV).     

AHP构造增长因素综合指标评价经济增长

将增长因素分析法中的增长因素作为指标,利用AHP计算其综合权重,然后对各因素的观测值加权求和得经济增长综合指标值,实现对经济增长的量化评价;并由此利用SPSS对1991至1998年我国30个省、直辖市、自治区建材工业的经济增长的实证分析结果进行评价。     

Controlled growth of ZnO array on FTO glass substrate by electrodeposition

In this study, ZnO nanotube and nanorod array films were respectively synthesized directly on F-doped SnO2 glass substrate (FTO) using a direct electrodeposition from a simple aqueous zinc salt solution. The effects of potential value, electro-deposition mode and solution stirring speed on the product morphology were investigated. Controlling the reaction under poten-tiostatic condition of -0.7 V at stirring speed of 300 r/min, large-scale nanotube arrays perpendicular to the substrate can be synthesized at a low temperature of 70 ℃. By varying the reaction parameters, we can also obtain ZnO nanorod arrays. The results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy have been provided to characterize the structure and morphology of the nanotube and nanorod arrays. Experiment results show that the as-obtained ZnO has a single crystalline structure and c-axis oriented direction. The room-temperature photolu-minescence spectrum of the ZnO nanotube array film displayed its high crystal property available as a photonic material. Electrodeposition is an effective method to prepare ZnO nanotube array films in quantity.     

Platelet-derived growth factor from astrocytes drives the clock that times oligodendrocyte development in culture

The various cell types in a multicellular animal differentiate on a predictable schedule but the mechanisms responsible for timing cell differentiation are largely unknown. We have studied a population of bipotential glial (O-2A) progenitor cells in the developing rat optic nerve that gives rise to oligodendrocytes beginning at birth and to type-2 astrocytes beginning in the second postnatal week. Whereas, in vivo, these O-2A progenitor cells proliferate and give rise to postimitotic oligodendrocytes over several weeks, in serum-free (or low-serum) culture they stop dividing prematurely and differentiate into oligodendrocytes within two or three days. The normal timing of oligodendrocyte development can be restored if embryonic optic-nerve cells are cultured in medium conditioned by type-1 astrocytes, the first glial cells to differentiate in the nerve: in this case the progenitor cells continue to proliferate, the first oligodendrocytes appear on the equivalent of the day of birth, and new oligodendrocytes continue to develop over several weeks, just as in vivo. Here we show that platelet-derived growth factor (PDGF) can replace type-1-astrocyte-conditioned medium in restoring the normal timing of oligodendrocyte differentiation in vitro and that anti-PDGF antibodies inhibit this property of the appropriately conditioned medium. We also show that PDGF is present in the developing optic nerve. These findings suggest that type-1-astrocyte-derived PDGF drives the clock that times oligodendrocyte development.     

2个置换因子循环矩阵相乘的快速傅氏变换法

借助于快速傅氏变换(FFT)技术,给出了计算2个n阶置换因子循环矩阵之乘积阵的一种快速算法,其算术复杂性为O(nlog2n),最后给出一个算例.     

Expression of peptide chain release factor 2 requires high-efficiency frameshift

Peptide chain release factors are soluble proteins that participate in the stop codon-dependent termination of polypeptide biosynthesis. In Escherichia coli, two release factors are necessary for peptide chain termination: release factor 1 (RF1) specifies UAG- and UAA-dependent termination whereas release factor 2 (RF2) specifies UGA- and UAA-dependent termination. Release factors are found in low concentrations relative to other translation factors, suggesting that their expression is tightly regulated and, accordingly, making the study of their structure-function relationship difficult. RF1 and RF2 exhibit significant sequence homology, probably reflecting their similar functions and perhaps a common evolutionary origin. DNA and peptide sequencing have suggested the existence of a unique mechanism for the autogenous regulation of RF2 in which an in-frame UGA stop codon requires an obligatory +1 frameshift within the coding region of the RF2 gene. In this report we present in vitro experimental results consistent with the autogenous regulation of RF2. Additionally, we used RF2-lacZ gene fusions to demonstrate that autogenous regulation occurs, at least in part, by premature termination at the in-frame stop codon, since deletion of this stop codon leads to overproduction of the RF2-LacZ fusion protein. Frameshifting at this premature termination codon occurs at the remarkably high rate of 50%.