pSP偶联低分子量壳聚糖介导siRNA对靶基因的沉默

放射性标记针对荧光素酶报告基因（Luc）的siRNA,与不同分子量的壳聚糖（CS）制备成CS/siRNA复合物,转染可稳定表达Luc基因的MDA-MB-231/Luc人乳腺癌细胞系.与 较大分子量壳聚糖相比,低分子量壳聚糖（LMWC）与siRNA形成的复合物具有更小的粒径及更强的siRNA转染能力,但是对靶基因的沉默效应却不高. 其原因归咎于低分子量壳聚糖（Mr为2 000或5 000,LMWC）与siRNA间强烈的电荷引力限制了siRNA在细胞内的释放.合成基序为LLLRRRDNEY*FY*VRRLL的可磷酸化短肽(pSP)与LMWC相偶联,合成pSP-LMWC.分别对siRNA及pSP-LMWC进行FAM及Dabcyl标记,利用FRET技术检测细胞内pSP-LMWC与siRNA的解离.结果表明,pSP修饰可大幅度增加siRNA与LMWC在细胞内的解离,成为有功能的游离形式,从而显著下调靶基因的表达.本文的结果表明,低分子量壳聚糖具有良好的siRNA递送能力,促进其与siRNA在细胞内的解离可有效提高siRNA对靶基因的沉默效应.     

Loss of meiosis in Aspergillus

If strictly mitotic asexual fungi lack recombination, the conventional view predicts that they are recent derivatives from older meiotic lineages. We tested this by inferring phylogenetic relationships among closely related meiotic and strictly mitotic taxa with Aspergillus conidial (mitotic) states. Phylogenies were constructed by using DNA sequences from the mitochondrial small ribosomal subunit, the nuclear ribosomal internal transcribed spacers, and the nuclear 5.8S ribosomal gene. Over 920 bp of sequence was analyzed for each taxon. Phylogenetic analysis of both the mitochondrial and nuclear data sets showed at least four clades that possess both meiotic and strictly mitotic taxa. These results support the hypothesis that strictly mitotic lineages arise frequently from more ancient meiotic lineages with Aspergillus conidial states. Many of the strictly mitotic species examined retained characters that may be vestiges of a meiotic state, including the production of sclerotia, sclerotium-like structures, and hulle cells.      

Rating of perceived exertion as a tool for prescribing and self regulating interval training: a pilot study

The aim of the present study was to analyse the usefulness of the 6-20 rating of perceived exertion (RPE) scale for prescribing and self-regulating high-intensity interval training (HIT) in young individuals. Eight healthy young subjects (age = 27.5±6.7 years) performed maximal graded exercise testing to determine their maximal and reserve heart rate (HR). Subjects then performed two HIT sessions (20 min on a treadmill) prescribed and regulated by their HR (HR: 1 min at 50% alternated with 1 min at 85% of reserve HR) or RPE (RPE: 1 minute at the 9-11 level [very light-fairly light] alternated with 1 minute at the 15-17 level [hard-very hard]) in random order. HR response and walking/running speed during the 20 min of exercise were compared between sessions. No significant difference between sessions was observed in HR during low- (HR: 135±15 bpm; RPE: 138±20 bpm) and high-intensity intervals (HR: 168±15 bpm; RPE: 170±18 bpm). Walking/running speed during low- (HR: 5.7±1.2 km · h⁻¹; RPE: 5.7±1.3 km · h⁻¹) and high-intensity intervals (HR: 7.8±1.9 km · h⁻¹; RPE: 8.2±1.7 km · h⁻¹) was also not different between sessions. No significant differences were observed in HR response and walking/running speed between HIT sessions prescribed and regulated by HR or RPE. This finding suggests that the 6-20 RPE scale may be a useful tool for prescribing and self-regulating HIT in young subjects.     

类杆菌分类的脱氢酶系列

国外已建立了4h水解酶色原底物系列,成功地用于厌氧菌的分类与鉴定,鉴于国内的无系列水解底物,我们对厌氧菌系列脱氢酶进行了研究,以便建立一种快速鉴定系列。为此选择类杆菌的参考株作为分类单位,以不同的糖、氨基酸和有机酸的天然底物纸片与细菌完整细胞进行酶学反应,并以四唑盐受氢后以变色效应来指示酶的存在。筛选了18项脱氢底物与色氨酸、尿素一起,组成20项以检测细菌脱氢酶为主的系列,研究发现完整的菌细胞可以较好地表现底物的脱氢酶活性,酶的分布具有菌种特征,这个系列在有氧条件下,30～60min出现明显的可见反应。以4株脆类杆菌参考株进行24次重复试验,其中9项的阳性概率为0.99,7项为0.01,其它4项分别是0.03,0.125,0.5和0.66。尤其胆酸脱氢酶与常规胆汁抑制试验有较好的相关性,有可能取代厌氧菌分类中有要意义的20％胆汁抑制实验。     

The phylogenetic status of arthropods, as inferred from 18S rRNA sequences

Partial 18S rRNA sequences of five chelicerate arthropods plus a crustacean, myriapod, insect, chordate, echinoderm, annelid, and platyhelminth were compared. The sequence data were used to infer phylogeny by using a maximum-parsimony method, an evolutionary-distance method, and the evolutionary-parsimony method. The phylogenetic inferences generated by maximum-parsimony and distance methods support both monophyly of the Arthropoda and monophyly of the Chelicerata within the Arthropoda. These results are congruent with phylogenies based on rigorous cladistic analyses of morphological characters. Results support the inclusion of the Arthropoda within a spiralian or protostome coelomate clade that is the sister group of a deuterostome clade, refuting the hypothesis that the arthropods represent the "primitive" sister group of a protostome coelomate clade. Bootstrap analyses and consideration of all trees within 1% of the length of the most parsimonious tree suggest that relationships between the nonchelicerate arthropods and relationships within the chelicerate clade cannot be reliably inferred with the partial 18S rRNA sequence data. With the evolutionary-parsimony method, support for monophyly of the Arthropoda is found in the majority of the combinations analyzed if the coelomates are used as "outgroups." Monophyly of the Chelicerata is supported in most combinations assessed. Our analyses also indicate that the evolutionary-parsimony method, like distance and parsimony, may be biased by taxa with long branches. We suggest that a previous study's inference of the Arthropoda as paraphyletic may be the result of (a) having two few arthropod taxa available for analysis and (b) including long-branched taxa.      

膝关节挫伤的磁共振影像表现

目的 :探讨磁共振短时的反转恢复序列 (STIR)在膝关节骨挫伤中的临床应用。方法 :通过 32例膝关节外伤病例在常规SE序列、FSE序列和STIR序列中的影像表现 ,分析STIR序列的优越性。结果 :32例共 45个骨挫伤病灶 ,T1W发现 38个 (占 84% ) ,T2W发现 37个 (占 82 % ) ,STIR序列病灶全部显示( 1 0 0 % )。结论 :STIR序列对骨挫伤的敏感性较高 ,能显示微小的骨髓水肿 ,充血及骨小梁的微骨折及其周围的骨软骨、关节囊的细微变化 ,对膝关节外伤具有较高价值。     

癫痫先兆探测治疗仪的设计

本文介绍一种能自动探测和识别癫痫先兆时的信号,并在病发早期自动发出音频电脉冲刺激患者,减弱癫痫病灶细胞活性的新型治疗仪的设计思路。