特异性microRNAs在心血管系统中的功能研究进展

MicroRNAs(miRNAs)是经核糖核酸酶(Dicer)加工后的一类非编码小RNA分子。在真核生物中,miRNA具有组织特异性和时序性,只在特定的组织和特定的发育阶段表达,在细胞生长和发育过程中起多种作用。miRNAs在心脏发育、形态生成、血管生成、心肌凋亡等多个生理病理过程中发挥重要作用。最近有大量研究发现某些特异性的miRNA对心血管的发育和心血管疾病有一定的影响。如miRNA-126调控血管生成;miRNA-143和miRNA-145决定血管平滑肌(VSMC)的分化和增殖;miRNA-208对心肌肥厚的调节;miRNA-1和miRNA-133影响心肌的发育、形态发生、心肌凋亡、心肌肥厚等。     

Notch信号途径与肿瘤血管发生

Notch信号途径广泛存在于无脊椎和哺乳动物体内,与肿瘤血管的萌发,尖端细胞的选择、血管分支的出现、脉管系统的成熟、以及血管损伤后修复等多个阶段均存在密切的关系.在血管发生过程中Notch信号途径主要受到VEGFs的调节,通过发挥抑制作用减少尖端细胞的数量和脉管分支的出现.对Notch信号途径的研究有可能成为未来肿瘤血管抑制治疗的新靶点.本文就Notch信号途径及与肿瘤血管发生之间的关系做一综述.     

川西米亚罗林区冷杉林群落特征与生态因子的关系

冷杉林是川西高山峡谷地区的地带性植被。以米亚罗林区的森林小班数据为基础,分析了该地区天然冷杉林的树高、胸径和蓄积量随不同生态因子的变化趋势及分布格局,并探讨了冷杉林最适宜的分布环境。结果表明:冷杉林的树高和胸径随着海拔的升高均呈现单峰曲线变化趋势,蓄积量则随着海拔梯度的升高呈波动上升趋势,这些现象可能与小环境的变化、人为干扰有关;冷杉林的适宜生态因子范围为:海拔3500～4000m、土壤厚度50～79cm、坡度40°～49°的中、上位阴坡和半阴坡;海拔3800～3900m为冷杉林的最集中分布区域,该区域中影响冷杉林群落特征的生态因子排序为坡位、土壤厚度、坡度、坡向。     

Determination of penehyclidine by gas chromatographic-mass spectrometry and its application to pharmacokinetics in humans, rabbits and mice

A sensitive and specific gas chromatographic-mass spectrometry with the extracted ion chromatograms (GC-MS/EIC) method has been developed and validated for the identification and quantification of penehyclidine (PH) in human and animal blood. The chromatography was on HP-5 capillary column (12 m x 0.2 mm x 0.3 microm). PH-d(5) was selected as the internal standard (IS). Simultaneous MS detection of PH and IS was performed at m/z 315 (PH) and m/z 320 (PH-d(5)), and the EIC of the two compounds was at 175 and 180. PH and PH-d(5) eluted at approximately 8.2 min and no endogenous materials interfered with their measurement. Linearity was obtained over the concentration range of 0.1-100 ng/ml in the blood. The lower limit of quantification (LLOQ) was reproducible at 50 pg/ml in both human and animal blood. The within-day and between-day precisions were no more than 9.1%. This method was successfully applied to quantification and pharmacokinetic studies of PH in the subjects. The concentration-time profiles of PH in humans, rabbits and mice were all fitted to first order absorption two-compartment open model after i.m. a single dose. The differences in absorption, distribution and elimination of PH among the species were found. The results provided the important information for developing a novel anti-cholinergic drug and for obtaining a more effectual remedy in clinical practice.     

Sorting signals required for trafficking of the cysteine-rich acidic repetitive transmembrane protein in Trypanosoma brucei

In trypanosomatids, endocytosis and exocytosis are restricted to the flagellar pocket (FP). The cysteine-rich acidic repetitive transmembrane (CRAM) protein is located at the FP of Trypanosoma brucei and potentially functions as a receptor or an essential component for lipoprotein uptake. We characterized sorting determinants involved in efficient trafficking of CRAM to and from the FP of T. brucei. Previous studies indicated the presence of signals in the CRAM C terminus, specific for its localization to the FP and for efficient endocytosis (H. Yang, D. G. Russell, B. Zeng, M. Eiki, and M.G.-S. Lee, Mol. Cell. Biol. 20:5149-5163, 2000.) To delineate functional domains of putative sorting signals, we performed a mutagenesis series of the CRAM C terminus. Subcellular localization of CRAM mutants demonstrated that the amino acid sequence between -5 and -14 (referred to as a transport signal) is essential for exporting CRAM from the endoplasmic reticulum to the FP, and mutations of amino acids at -12 (V), -10 (V), or -5 (D) led to retention of CRAM in the endoplasmic reticulum. Comparison of the endocytosis efficiency of CRAM mutants demonstrated that the sequence from amino acid -5 to -23 (referred to as a putative endocytosis signal) is required for efficient endocytosis and overlaps with the transport signal. Apparently the CRAM-derived sorting signal can efficiently interact with the T. brucei micro1 adaptin, and mutations at amino acids essential for the function of the transport signal abolished the interaction of the signal with T. brucei micro1, strengthening the hypothesis of the involvement of the clathrin- and adaptor-dependent pathway in trafficking of CRAM via the FP.     

The inhibition and treatment of breast cancer with poly (ADP-ribose) polymerase (PARP-1) inhibitors

BRCA1 and BRCA2 mutations are responsible for most familial breast carcinomas. Recent reports carried out in non-cancerous mouse BRCA1- or BRCA2-deficient embryonic stem (ES) cells, and hamster BRCA2-deficient cells have demonstrated that the targeted inhibition of poly(ADP-ribose) polymerase (PARP-1) kills BRCA mutant cells with high specificity. Although these studies bring hope for BRCA mutation carriers, the effectiveness of PARP-1 inhibitors for breast cancer remains elusive. Here we present the first in vivo demonstration of PARP-1 activity in BRCA1-deficient mammary tumors and describe the effects of PARP-1 inhibitors (AG14361, NU1025, and 3-aminobenzamide) on BRCA1-deficient ES cells, mouse and human breast cancer cells. AG14361 was highly selective for BRCA1-/- ES cells; however, NU1025 and 3-aminobenzamide were relatively non-selective. In allografts of na?ve ES BRCA1-/- cells there was either partial or complete remission of tumors. However, in allografts of mouse, BRCA1-/- mammary tumors, there was no tumor regression or remission although a partial inhibition of tumor growth was observed in both the BRCA1-/- and BRCA1+/+ allografts. In human tumor cells, PARP-1 inhibitors showed no difference in vitro in limiting the growth of mammary tumors irrespective of their BRCA1 status. These results suggest that PARP-1 inhibitors may non-specifically inhibit the growth of mammary tumors.     

Potent histamine-releasing activity of atrahagin, a novel snake venom metalloproteinase

Poisonous snakebite wound is a popular disease worldwide. However, the pathogenesis remains unclear. In the present study, a novel metalloproteinase atrahagin in Chinese cobra (Naja atra) snake venom was purified, using heparin-sepharose followed by Superdex 75 gel filtration chromatography. Apart from its alpha-fibrinogenase activity, atrahagin potently activated human colon, lung and tonsil mast cells with the net histamine release being 25.9+/-4.4, 17.0+/-1.9, 13.2+/-3.6%, respectively. Time course studies revealed that the peak histamine release induced by atrahagin occurred at 12, 12 and 8 min following incubation of the enzyme with colon, lung and tonsil mast cells, respectively. The response of mast cells to atrahagin was abolished by preincubation of the cells with metabolic inhibitors or pertussis toxin, and by removal of Ca2+ and Mg2+ from the challenge buffer. In conclusion, activation of human mast cells by atrahagin indicated that the enzyme might contribute to the pathogenesis of snakebite wound.     

Normal versus gamma: stochastic models of copepod molting rate

Molting rate is a key life history parameter in copepods. Sincecopepod population growth is an inherently exponential process,accurate formulation of molting rate is of critical importance.Many experiments have been conducted to culture different copepodspecies under varying temperatures and food concentrations.Probability density functions (PDFs) then were used to estimatethe median development time (MDT) of different copepod stagesfrom the experimental data. These MDTs are used in copepod populationmodels. Asymmetrical PDFs are widely used to model molting rate,because the shapes of these curves are similar to laboratorydata on cohort development. In this paper, we developed an individualstochastic model (ISM) to simulate the molting rate with differentPDFs. We showed that there was no connection between the asymmetryof cohorts and the asymmetry of the molting PDF. Although age-within-stagemodels have been widely used to simulate copepod populationdynamics, we found that none had used the correct formulationof molting rate. The population model requires the probabilityof molting at each time step, whereas the laboratory-derivedPDF is the frequency distribution of stage duration. Therefore,the PDF cannot be applied directly to the population model.We present here a corrected formula based on the PDF for usein copepod population models, termed the probability of moltingfor remaining individuals (PMR). Despite emphasis on use ofthe gamma function for copepod molting, we found simpler functionswork equally well, but that prior use of incorrect molting ratefunctions in copepod models can seriously overestimate generationtime.