淡水涡虫染色体的制备方法

以涡虫的再生组织为材料,用秋水仙素处理长有再生组织的涡虫片段,并通过改善各种实验条件,得到高清晰度的染色体图谱。结果表明,本方法简便易行,制成的染色体分散好,形态清晰,适用于对涡虫染色体的进一步研究。     

An Improved Method for the Preparation of Type I Collagen From Skin

Soluble type 1 collagen (COL1) is used extensively as an adhesive substrate for cell cultures and as a cellular scaffold for regenerative applications. Clinically, this protein is widely used for cosmetic surgery, dermal injections, bone grafting, and reconstructive surgery. The sources of COL1 for these procedures are commonly nonhuman, which increases the potential for inflammation and rejection as well as xenobiotic disease transmission. In view of this, a method to efficiently and quickly purify COL1 from limited quantities of autologously-derived tissues would circumvent many of these issues; however, standard isolation protocols are lengthy and often require large quantities of collagenous tissues. Here, we demonstrate an efficient COL1 extraction method that reduces the time needed to isolate and purify this protein from about 10 days to less than 3 hr. We chose the dermis as our tissue source because of its availability during many surgical procedures. This method uses traditional extraction buffers combined with forceful agitation and centrifugal filtration to obtain highly-pure, soluble COL1 from small amounts of corium. Briefly, dermal biopsies are washed thoroughly in ice-cold dH₂O after removing fat, connective tissue, and hair. The skin samples are stripped of noncollagenous proteins and polysaccharides using 0.5 M sodium acetate and a high speed bench-top homogenizer. Collagen from residual solids is subsequently extracted with a 0.075 M sodium citrate buffer using the homogenizer. These extracts are purified using 100,000 MW cut-off centrifugal filters that yield COL1 preparations of comparable or superior quality to commercial products or those obtained using traditional procedures. We anticipate this method will facilitate the utilization of autologously-derived COL1 for a multitude of research and clinical applications.     

An Improved Method for the Synthesis of Flavanones

An isomerization of 2"-hydroxychalcones into the corresponding flavanones in ethanol in the presence of triethylamine is described.     

An Improved Method for the Study of Chromosomes

It has been felt strongly that the current methods for the fixation of chromosomes are inadequate, inasmuch as the reagents are unduly long in reaching the important elements of the cells, particularly the nucleus. A realization of this situation has been at the bottom of the development of the so-called smear method. This method can, however, be advantageously employed only where loose cells are available, as in the reproductive elements of plants and animals. The present author has found that cutting up the material in very thin slices of almost microscopical tenuity, and passing them immediately into the best fixing solutions, namely those containing osmic acid, gives excellent results. The material is then assembled on cards in accordance with the present author's mass method (for which see the original article), and after embedding in nitrocellulose is sectioned 5μ or even thinner. Practically all methods of staining may be used, but the most satisfactory results have been achieved with Heidenhain's hematoxylin bleached almost to disappearance and followed by prolonged treatment with an aqueous safranin. This differentiates the chromosomal structures extremely well. It is clear by this method that chromosomes in all cases consist of a ground substance in which are situated two chromatids. In the somatic tissues these chromatids are apparently generally spiral and run in opposite directions. The crossing points of these spirals are responsible for the optical illusion which has been designated the gene.     

An Improved Method for the Preparation of Methyl dichlorophosphite. A Key Reagent In the Phosphite Method of Oligonucleotide Synthesis

Abstract

The reaction between phosphorus trichloride (PCl₃) and trimethyl phosphite (CH₃O)3^p, has been examined by ³¹Pnmr, in order to achieve a simple and efficient procedure for the formation of methyl dichlorophosphite (CH₃OPCl₂), which is a key intermediate in the synthesis of oligonucleotides. The yield of the reaction was also studied on a preparative scale and it was found that the optimal condition is obtained when the reactants molar ratio is 1:1.     

组氨酸生产中间控制方法的研究

研究了组氨酸与Pauly试剂显色反应的适宜条件 ,并加入钠盐和酪氨酸对标准曲线进行校正后 ,作为组氨酸定量测定的工作曲线。该方法简便 ,快速 ,准确度高 ,重现性好     

An Improved Method for P2X7R Antagonist Screening

ATP physiologically activates the P2X7 receptor (P2X7R), a member of the P2X ionotropic receptor family. When activated by high concentrations of ATP (i.e., at inflammation sites), this receptor is capable of forming a pore that allows molecules of up to 900 Da to pass through. This receptor is upregulated in several diseases, particularly leukemia, rheumatoid arthritis and Alzheimer''s disease. A selective antagonist of this receptor could be useful in the treatment of P2X7R activation-related diseases. In the present study, we have evaluated several parameters using in vitro protocols to validate a high-throughput screening (HTS) method to identify P2X7R antagonists. We generated dose-response curves to determine the EC₅₀ value of the known agonist ATP and the IC_s50 values for the known antagonists Brilliant Blue G (BBG) and oxidized ATP (OATP). The values obtained were consistent with those found in the literature (0.7 ± 0.07 mM, 1.3-2.6 mM and 173-285 μM for ATP, BBG and OATP, respectively). The Z-factor, an important statistical tool that can be used to validate the robustness and suitability of an HTS assay, was 0.635 for PI uptake and 0.867 for LY uptake. No inter-operator variation was observed, and the results obtained using our improved method were reproducible. Our data indicate that our assay is suitable for the selective and reliable evaluation of P2X7 activity in multiwell plates using spectrophotometry-based methodology. This method might improve the high-throughput screening of conventional chemical or natural product libraries for possible candidate P2X7R antagonist or agonist     

An Improved Method for Standardization of Microspectrofluorometers

The use of meshed cadmium-zinc sulfide fluorescent particles in combination with an electron microscope locator grid greatly facilitates the standardization of miam spectrofluorometers. The fluorescent particles emit maximally at 570 nm, and the intensity of fluorescence is directly proportional to cross-sectional area when epi-illumination is used Details concerning technique and fluorescent particle characteristics are reported.     

An Improved Method for Estimating Macromolecular Synthesis

Estimating rates of DNA, RNA, and protein synthesis has beengreatly facilitated by the use of radioactive precursors. Currentlyavailable methods to assess macromolecular synthesis in higherplants are time-consuming and imprecise. In the procedure outlinedhere, the conventional method is simplified by processing thetissue intact. This method allows a rapid analysis and considerablyreduces the inherent variability associated with the conventionalmethod.     

一种改进的蛋白质超薄凝胶电泳方法

介绍了一种将聚丙烯酰胺凝胶固定在电泳夹板上的蛋白质电泳方法.通过此方法蛋白质电泳可以在0.4 mm厚的聚丙烯酰胺凝胶上进行.实验证明,经此方法处理的玻板结合凝胶非常牢固,在电泳后的所有处理步骤中都不会发生凝胶脱落现象.     

An Improved Method of Decalcification

Following several experimental investigations, an improved method of decalcification has been devised. The principle of this decalcification method is to obtain complete decalcification by a mixture of as high pH as possible without diminishing the stainability of the Nissl-granules (with Einarson's progressive staining method by means of gallocyanin). This is accomplished by the help of a buffer solution of equal parts of 8 N formic acid and 1 N sodium formate (pH 2.2). After-treatment consists only in rinsing in flowing water for 24 hours. Dehydration is in alcohol (70%, 96%, 100%); cedar oil; ligroin. Embedding in paraffin follows.     

2-Cyano-4-fluoro-1-thiovalylpyrrolidine analogues as potent inhibitors of DPP-IV

We report the synthesis and biological activity of a series of 2-cyano-4-fluoro-1-thiovalylpyrrolidine inhibitors of DPP-IV. Within this series, compound 19 provided a potent, selective, and orally active DPP-IV inhibitor which demonstrated a very long duration of action in both rat and dog.     

An Improved Method of Decalcification

Following several experimental investigations, an improved method of decalcification has been devised. The principle of this decalcification method is to obtain complete decalcification by a mixture of as high pH as possible without diminishing the stainability of the Nissl-granules (with Einarson's progressive staining method by means of gallocyanin). This is accomplished by the help of a buffer solution of equal parts of 8 N formic acid and 1 N sodium formate (pH 2.2). After-treatment consists only in rinsing in flowing water for 24 hours. Dehydration is in alcohol (70%, 96%, 100%); cedar oil; ligroin. Embedding in paraffin follows.     

生长曲线参数估计的一种新方法-优化回归组合法

在现有文献研究的基础上,对生长曲线参数估计问题又作了进一步研究,给出了生长曲线参数估计的一种新方法优化回归组合法,该方法创造性地将最优化方法与回归方法结合在一起,利用最优化理论中的区间搜索和一维搜索,可以得到一系列c^＊值,利用回归方法可求得与其相对应的一系列a和b的值．当c取最优值c时,a和b便得到最优值a^＊和b^＊经示例计算表明,这种参数估计法具有较高的精度,     

An Improved Method for Preparing Anti-B Lymphocyte Serum

THE preparation of a heterologous antiserum specific to the bursa equivalent (B) lymphoid cells of the mouse requires extensive absorption with mouse tissues, especially thymocytes, to obtain specificity. The cell surface antigen(s) against which the serum reacts has been termed mouse specific bone marrow derived lymphocyte antigen(s) (MBLA)¹. The specificity of anti-MBLA for the B lymphoid population has been demonstrated by cytotoxicity tests, by its ability to inhibit a portion of antigen binding cells and by adoptive immune responses of antiserum purified lymphoid cells (refs. 1 and 2 and unpublished results of E. Möller and myself).     

An Improved Method for Chromosome Counting in Maize

An improved method for counting chromosomes in maize (Zea mays L.) is presented. Application of cold treatment (5C, 24 hr), heat treatment (42 C, 5 min) and a second cold treatment (5C, 24 hr) to root tips before fixation increased the number of condensed and dispersed countable metaphase chromosome figures. Fixed root tips were prepared by the enzymatic maceration-air drying method and preparations were stained with acetic orcein. Under favorable conditions, one preparation with 50-100 countable chromosome figures could be obtained in diploid maize using this method. Conditions affecting the dispersion of the chromosomes are described. This technique is especially useful for determining the somatic chromosome number in triploid and tetraploid maize lines.