长爪沙鼠线粒体DNA控制区全序列测定及分析

目的对长爪沙鼠线粒体DNA控制区全序列进行测定,并对其进行鉴定及进化分析。方法根据长爪沙鼠已知基因序列设计引物,采用PCR产物测序法,对所得的片段进行测序鉴定。结合已公布啮齿类动物D-loop区序列,分析其碱基组成、遗传距离、并基于最小进化法和UPGMA法构建系统进化树。结果获得长爪沙鼠D-loop区序列,其与家鼠、小家鼠和仓鼠平均同源性为58%;碱基组成分析显示,长爪沙鼠与啮齿类动物有相似的碱基组成和碱基偏离,其A-skew和G-skew分别为0.0047和-0.28。进化分析结果显示,长爪沙鼠与家鼠（0.35）、黑家鼠（0.38）和仓鼠（0.39）具有较近的遗传距离,其分化顺序为跳鼠、蔗鼠、长爪沙鼠、仓鼠、家鼠和小家鼠。结论本研究获得长爪沙鼠D-loop区全序列,确定了长爪沙鼠与仓鼠、家鼠、小家鼠及其它啮齿动物的进化关系,为长爪沙鼠进化研究、线粒体的结构和功能研究奠定基础。     

Cell cycle related proteins in hyperplasia of usual type in breast specimens of patients with and without breast cancer

Background  

Hyperplasia of usual type (HUT) is a common proliferative lesion associated with a slight elevated risk for subsequent development of breast cancer. Cell cycle-related proteins would be helpful to determine the putative role of these markers in the process of mammary carcinogenesis. The aim of this study was to analyze the expression of cell cycle related proteins in HUT of breast specimens of patients with and without breast cancer, and compare this expression with areas of invasive carcinomas.     

Microtubules and cyclic amp in human leukocytes: on the order of things

We have shown previously that the β-adrenergic agonist isoproterenol (2μM) and the phosphodiesterase inhibitor isobutylmethylxanthine (1 mM) produce a much greater increase in cyclic AMP in human leukocytes that have been pretreated with colchicine (or with other agents that affect microtubule assembly) than in control leukocytes. The effects of colchicines were both time- and dose-dependant. These and other data suggested that the generation of cyclic AMP is normally restricted by an intact system of cytoplasmic microtubules. If so, then the same time and dose dependencies might apply to other colchicines-induced changes in leukocyte function. We have now assayed the distribution of concanavalin A (Con A)-receptor complexes on the leukocyte membrane, taking into account that leukocytes competent to assemble microtubules show a uniform distribution of surface- bound Con A whereas microtubule-deficient cells accumulate Con A in surface caps. We have found that the effect of colchicine on capping is also both time- and dose dependent, and that the dose-response relationships conform to those required to increase cyclic AMP levels. These findings provide further evidence that both colchicine-induced Con-A capping and colchicine- induced cyclic AMP generation depend upon the relaxation of constraints normally imposed by cytoplasmic microtubules upon the plasma membrane, which limit, respectively, lateral mobility of the lectin-receptor complexes, and expression of hormone-sensitive adenylate cyclase. Moreover, colchicine-induced Con-A cap formation is not affected even by very large changes in leukocyte cyclic AMP levels. Thus, elevated cyclic AMP levels do not appear to promote the dissolution of microtubules; rather, the dissolution of microtubules permits the generation of increased amounts of cyclic AMP.     

A cytomorphological analysis of the adhesion of fungi of the genus Candida to human and animal epithelial cells

Morphological pattern of adherence of Candida genus fungi to human and animal epithelial cells have been studied using histological and cytological methods. The interspecific differences of epithelial adhesive properties were observed: in one case, the mucous membrane epitheliocytes of different localization had different adhesive properties. Adhesive properties vary significantly within one type of epithelial cells. In individual epitheliocyte, the adherence of fungal blastospores was nonuniform: the greater density was observed in peripheral areas of cytoplasm.     

A modular treatment of molecular traffic through the active site of cholinesterase

We present a model for the molecular traffic of ligands, substrates, and products through the active site of cholinesterases (ChEs). First, we describe a common treatment of the diffusion to a buried active site of cationic and neutral species. We then explain the specificity of ChEs for cationic ligands and substrates by introducing two additional components to this common treatment. The first module is a surface trap for cationic species at the entrance to the active-site gorge that operates through local, short-range electrostatic interactions and is independent of ionic strength. The second module is an ionic-strength-dependent steering mechanism generated by long-range electrostatic interactions arising from the overall distribution of charges in ChEs. Our calculations show that diffusion of charged ligands relative to neutral isosteric analogs is enhanced approximately 10-fold by the surface trap, while electrostatic steering contributes only a 1.5- to 2-fold rate enhancement at physiological salt concentration. We model clearance of cationic products from the active-site gorge as analogous to the escape of a particle from a one-dimensional well in the presence of a linear electrostatic potential. We evaluate the potential inside the gorge and provide evidence that while contributing to the steering of cationic species toward the active site, it does not appreciably retard their clearance. This optimal fine-tuning of global and local electrostatic interactions endows ChEs with maximum catalytic efficiency and specificity for a positively charged substrate, while at the same time not hindering clearance of the positively charged products.     

Evaluation of endothelial permeability in brain tumors by dynamic magnetic resonance tomography with magnevist contrast imaging on low-field MR-tomograph

In order to study the endothelial permeability to hydrophilic macromolecules in brain tumors we have developed a technique based on Gjedde-Rutland-Patlak approach to dynamic MRI study with Gd-DTPA injected intravenously, performed with low-field MRI tomograph Magnetom Open (Siemens medical). 27 patients with various brain tumors were referred for the study. The indices of Gd-DTPA transport to tumor tissue (KGd-DTPA) vary substantially, depending on the degree of malignancy and deliver essential information on microvascular permeability of tumor capillary bed.     

豆科黄华属植物种子表面特征的研究

在扫描电镜下观察了豆科黄华属Thermopsis 18种植物种子的表面纹饰,发现 T．alpina,T.bar- bata,T．inflata,T．lupinoides,T. licentiana,T.smithiana和T．turkestanica的种子表面为粗网状,T californica,T.divaricarpa,T. macrophylla,T．mollis的种子表面为细网状,T.gracilis,T.montana,T. fabacea的种子表面为相对平滑型纹饰,T．alterniflora的种子表面为不规则条形,T．chinensis的种子表 面为粘膜状,T.rhombifolia的种子表面为条形及 T．viuosa的种子表面为碎屑状纹饰。结果表明黄华属的种子表面特征对属下类群的划分有一定意义,对澄清某些混乱的种有一定价值。