小鼠卵慢速和快速降温及玻璃化冻存的比较研究

本文用４种冷冻模式：慢速降温（ＳＬ）,超快速降温（Ｑ１）和防冻剂组成不同的玻璃化法（Ｒ－ＦＶＭ和ＭＶＭ）对昆明小鼠卵进行冷冻保存的比较研究,并用体外受精技术检测冷冻复苏卵的受精能力。ＳＬ和Ｒ－ＦＶＭ的存活率分别为５５．１±１．２和６５．９±７．９,显著高于Ｑ１（２４．２±７．３）和ＭＶＭ（４．５±２．４）其受精率分别为７２．８±１．８和７３．９±０．４显著高于Ｑ１（５８．６±１１．２）和ＭＶＭ（４１．５±８．５）,而与对照组（７７．５±３．９）相似。结果表明：１）慢速降温程序（ＳＬ）和同时含有渗透性和非渗透性防冻剂的玻璃化法（Ｆ—ＲＶＭ）较适宜昆明小鼠卵的冻存;２）同时考虑冻存过程中的冰晶损伤和渗透压损伤是获得较好冻存结果的关键。     

滇金丝猴驯养的初步研究

本文报道的６只慎金丝猴均捕自同一野生种群。由于在运动途中采用了降低应激反应药物,动物得以安全运出。笼养期间,试投以各种本地产植物的叶、花、果和蔬菜为食,结果有５６种为动物所接受。说明金丝猴的食性狭窄主要是受栖息地的限制。在以这些食物为主食的条件下,分别笼养了１４个月的３只（♀）、６个月２只（♂）和８０个月１只（♀）的滇金丝猴目前健康状况良好：成年人体的体重多有所增加,幼体的生长发育良好,结核菌素试     

5种大肠埃希氏菌Col质粒接合传递实验研究

以5种61株Col~ 大肠埃希氏菌为供体,与受体E.Coli K_(12)进行接合实验,结果有16株供体菌的Col质粒传递给K_(12),占25.4％。其中NPEC、ETEC、EPEC、EIEC、EAEC的传递比率分别是8/22、 4/21、2/15、1/2、1/1。按传递方式分类,52株耐药供体菌有10株的Col质粒和耐药标记(或R质粒)发生共同传递,占19.2％,伴发Col质粒传递的耐药标记有8种,其中TC、SM、COS、KM的并发传递率较高(16—20％)。不同耐药标记菌株的Col质粒传递率范围在0—66.7％。在8株敏感菌和1株耐药菌中有6株Col质粒发生单独传递,占66.7％。实验发现4个配对组的Col质粒和R(r)质粒发生分离而独自传递。本文分析了Col质粒传递方式和耐药性的关系,同时讨论了接合传递的不同方法。为阐明和研究R~ Col~ 肠道菌的演变及其对正常菌群生态平衡的影响提供遗传学依据。     

Study on air pollution in Beijing’s major industrial areas using multielements in biomonitors and NAA techniques

Three kinds of plant leaves, Chinese white aspen, arborvitae, and pine needles, have been sampled from the Yanshan Oil refinery complex, the Capital Iron and Steel Factory, and Badachu, a control area in Beijing, as biomonitors for air-pollution studies. Each sample was divided into two parts, washed, and unwashed. Thirty-one trace elements (As, Au, Br, Ca, Cd, K, La, Lu, Mo, Na, Sb, Sm, U, W, Yb, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, Hg, Rb, Sc, Se, Sr, Ta, Tb, Th, and Zn) have been determined by using the relative and the K₀ methods of instrumental neutron activation analysis (NAA) techniques. The results indicated the following: (1) The concentration of trace elements in unwashed samples are much higher than these in washed samples; (2) the area around Capital Iron and Steel Factory is heavily polluted, and the Yanshan Oil refinery complex area is moderately polluted; (3) Chinese white aspen is a good biomonitor in particular seasons and pine needles are better than arborvitae for yearly monitoring; (4) elements As, Cd, Hg, Co, Rb, Sb, W, and Zn are highly absorbed by Chinese white aspen. Pine needles are sensitive for the absorption the elements Br, Cr, Cd, Fe, Sc, Cs and rare earth elements, but arborvitae is very sensitive for the absorption of Sr.     

Preliminary study on the relationship between osteoporosis and trace elements with rat models

Thirty rats were divided randomly into five groups and fed with different feeds. They were killed after 2 mo. Right thighs of these rats were taken as samples. Bone mineral densities of these samples were measured by the double-energy x-ray bone mineral densitometer, and trace elements contents of the samples were analyzed by neutron activation analysis. Results of the experiments showed that some elements were well correlated with others, and there were obvious variances between some elements of the normal group and those of other four groups.     

天然可降解生物材料在组织工程中的应用研究进展

细胞培养支架材料是组织工程学的重要研究内容之一 ,是实现产业化的关键。天然可降解生物材料是细胞培养支架材料中的重要组成部分 ,目前用于细胞培养支架的天然可降解生物材料主要有多糖类和蛋白质类。多糖类主要包括壳多糖、透明质酸 ;蛋白质类主要包括胶原纤维蛋白和血纤维蛋白。     

Benefits and Challenges with Applying Unique Molecular Identifiers in Next Generation Sequencing to Detect Low Frequency Mutations

Indexing individual template molecules with a unique identifier (UID) before PCR and deep sequencing is promising for detecting low frequency mutations, as true mutations could be distinguished from PCR errors or sequencing errors based on consensus among reads sharing same index. In an effort to develop a robust assay to detect from urine low-abundant bladder cancer cells carrying well-documented mutations, we have tested the idea first on a set of mock templates, with wild type and known mutants mixed at defined ratios. We have measured the combined error rate for PCR and Illumina sequencing at each nucleotide position of three exons, and demonstrated the power of a UID in distinguishing and correcting errors. In addition, we have demonstrated that PCR sampling bias, rather than PCR errors, challenges the UID-deep sequencing method in faithfully detecting low frequency mutation.     

Dissecting signaling pathways that govern self-renewal of rabbit embryonic stem cells

The pluripotency and self-renewal of embryonic stem cells (ESC) are regulated by a variety of cytokines/growth factors with some species differences. We reported previously that rabbit ESC (rESC) are more similar to primate ESC than to mouse ESC. However, the signaling pathways that regulate rESC self-renewal had not been identified. Here we show that inhibition of the transforming growth factor beta (TGFbeta), fibroblast growth factor (FGF), and canonical Wnt/beta-catenin (Wnt) pathways results in enhanced differentiation of rESC accompanied by down-regulation of Smad2/3 phosphorylation and beta-catenin expression and up-regulation of phosphorylation of Smad1 and beta-catenin. These results imply that the TGFbeta, FGF, and Wnt pathways are required for rESC self-renewal. Inhibition of the MAPK/ERK and PI3K/AKT pathways, which lie downstream of the FGF pathway, led to differentiation of rESC accompanied by down-regulation of phosphorylation of ERK1/2 or AKT, respectively. Long-term self-renewal of rESC could be achieved by adding a mixture of TGFbeta ligands (activin A, Nodal, or TGFbeta1) plus basic FGF (bFGF) and Noggin in the absence of serum and feeder cells. Our findings also suggest that there is a regulatory network consisting of the FGF, Wnt, and TGFbeta pathways that controls rESC pluripotency and self-renewal. We conclude that bFGF controls the stem cell properties of rESC both directly and indirectly through TGFbeta or other pathways, whereas the effect of Wnt on rESC might be mediated by the TGFbeta pathway.     

Practical Role of Mutation Analysis for Imatinib Treatment in Patients With Advanced Gastrointestinal Stromal Tumors: A Meta-Analysis

Background

Imatinib has become the standard first line treatment of gastrointestinal stromal tumors (GIST) in the advanced phase and adjuvant setting. We carried out an up-to-date meta-analysis to determine the practical role of mutation analysis for imatinib treatment in patients with advanced GIST.

Methods

Eligible studies were limited to imatinib treatment for patients with advanced GIST and reported on mutation analysis. Statistical analyses were conducted to calculate the odds ratio (OR), hazard ratio (HR) and 95% confidence interval (CI) using fixed-effects and random-effects models.

Results

A total of 2834 patients from 3 randomized controlled trials and 12 cohort studies were included. The ORs of response rates in KIT exon 11-mutant GISTs were 3.504 (95% CI 2.549-4.816, p<0.001) and 3.521 (95% CI 1.731-7.165, p=0.001) compared with KIT exon 9-mutant and wild type GISTs, respectively. The HRs of progression-free survival in KIT exon 11-mutant GISTs were 0.365 (95% CI 0.301-0.444, p<0.001) and 0.375 (95% CI 0.270-0.519, p<0.001) compared with KIT exon 9-mutant and wild type GISTs. The HRs of overall survival in KIT exon 11-mutant GISTs were 0.388 (95% CI 0.293-0.515, p<0.001) and 0.400 (95% CI 0.297-0.538, p<0.001) compared with KIT exon 9-mutant and wild type GISTs. No statistical significant differences were found between KIT exon 9-mutant and wild type. The overall response rate in KIT-exon 11-mutant GISTs were 70.5% (65%-75.9%) compared with 57.1% (51%-63.2%) in KIT-positive GISTs. No evidence of publication bias was observed.

Conclusion

Patients with advanced GIST harboring a KIT exon 11 mutation have the best response rate and long-term survival with imatinib treatment. Mutation analysis would be more helpful than KIT expression analysis to decide appropriate therapy for a specific patient.     

Complete genome sequencing and comparative analysis of the linezolid-resistant Enterococcus faecalis strain DENG1

Genome level analysis of bacterial strains provides information on genetic composition and resistance mechanisms to clinically relevant antibiotics. To date, whole genome characterization of linezolid-resistant Enterococcus faecalis isolated in the clinic is lacking. In this study, we report the entire genome sequence, genomic characteristics and virulence factors of a pathogenic E. faecalis strain, DENG1. Our results showed considerable differences in genomic characteristics and virulence factors compared with other E. faecalis strains (V583 and OG1RF). The genome of this LZD-resistant E. faecalis strain can be used as a reference to study the mechanism of LZD resistance and the phylogenetic relationship of E. faecalis strains worldwide.