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1.
Objective: To determine the effective nucleotide sites of ribozymes against HCV, and obtain a highly effective, nontoxic and inexpensive antisense ribozyme specific for HCV. Methods: Two effective ribozymes, targeted to HCV 5’NC region and C region, were designed and synthesized. Eukaryotic expression vectors, pSV2-gpt. CD-SR (, containing either HCRZNC or HCRZC were constructued and transfected into MT-2 cells, which had been infected by HCV. Quantitative PCR and hydridization were used to determine the effect of inhibition of HCV by ribozymes. Results: HCRZNC and HCRZC suppressed the replication of HCV by 54.7% and 62.1%, respectively. Furthermore, when both ribozymes were cotransfected into cells, they suppressed replication by 78.8%. Conclusion: Two specific antisense ribozymes have strong inhibitory effects on the replication of HCV in cultured cells, and have better effect when used together.  相似文献   

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INTRODUCTION Entomopathogenic nematodes of the generaSteinernema and Heterorhabditis have been used tocontrol a wide range of agriculturally important insectpests (Kaya and Gaugler, 1993). The mechanism bywhich these nematodes are able to infect and repro-duce in the insect host involves a mutual relationshipbetween the nematode and the symbiotic bacteria,Xenorhabdus spp. and Photorhabdus spp. (Akhurstand Dunphy, 1993; Forst and Nealson, 1996). Poinarand Thomas (1966) established tha…  相似文献   

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Objective: To study the roles of different truncated hepatitis C virus (HCV) core proteins (CORE) in the pathogenesis of HCV persistent infection and hepatocellular carcinoma (HCC) and to assess intracellular localization in transiently transfected cells. Methods: Seven truncated CORE-GFP (green fluorescent protein) fusion protein expression plasmids were constructed,which contained HCV CORE sequences derived from tumor tissues (BT) and non-tumor tissues (BNT) from one patient infected with HCV. Amino acid (aa) lengths were BT: 1-172 aa, 1-126 aa, 1-58 aa, 59-126 aa, 127-172 aa; BNT: 1-172 aa and C191:1-172 aa respectively. Subcellular localization of CORE-GFP was analyzed by con-focal laser scanning microscope. Apoptosis and necrosis were quantified by flow cytometry. Results: Different truncated CORE-GFP localized mainly in the cytoplasm, but nuclear staining was also observed. HCV CORE could induce apoptosis and necrosis, and different truncated COREs could induce cell apoptosis and necrosis at different levels. Among the same length 1-172 aa of BT, BNT and C191, the cell apoptosis and necrosis percentage of BT is highest, and C191 is the lowest (BT＞BNT＞C191). To the different fragment COREs of BT,N-terminal of CORE induced apoptosis and necrosis higher, compared with that of C-terminal (1-172 aa＞1-126 aa＞1-58aa＞ 127-172 aa＞59-126 aa). Conclusion: These results suggest HCV CORE could induce apoptosis and necrosis of cells, which might play an important role in the pathogenesis of HCV persistent infection and HCC and the different CORE domains of different HCV quasi-species might have some difference in their pathogenesis.  相似文献   

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INTRODUCTION Chronic infection by hepatitis B virus (HBV) isassociated with a high risk of liver cirrhosis and pri-mary hepatocellular carcinoma (HCC). It remains animportant global health problem with over 350 mil-lion chronic HBV carriers worldwide. Among thesechronic carriers, about one million people die ofHBV-associated liver failure or HCC annually (Kaoand Chen, 2002). Although chronically infected pa-tients have been treated with interferons and nucleo-side analogs, th…  相似文献   

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INTRODUCTION Pulmonary hypertension is not rare in humanwith some heart and lung diseases. Chronic pul-monary hypertension leads to structural alterationsof the lung vessels. The pathophysiology of thisremodeling process is still poorly understood.Furthermore, the structural damage of the lungvessels limits the clinical success of vasodilatortreatment. Assuming genetic susceptibility, shearstress and inflammation are the principal pathoge-netic factors involved in lung vessel remode…  相似文献   

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Two stable transformed lines containing antisense LeERT1 or LeERT2 sequences and their hybridized line were investigated to determine the effect of LeERT1 and LeERT2 specificity in the ethylene receptor family in tomato （Lycopersicon esculenturn Mill.） on ethylene signaling. The transgenic line alel containing antisense LeER T1 displayed shorter length of seedling grown in the dark and adult plant in the light, severe epinastic petiole, and accelerated abscission of petiole explant and senescence of flower explant, compared with its wild type B 1. The transgenic line ale2 containing antisense LeERT2 also exhibited shorter hypocotyls and slightly accelerated abscission. The phenotypes of cross line dale of LeERT1 and LeERT2 were close to alel in many aspects. These results suggested that LeERT1 probably plays a relatively important role in ethylene signaling of tomato growth and development.  相似文献   

8.
目的:探求适用于低收入人群十二指肠溃疡(DU)患者经济、有效的治疗方案。方法:将156例活动性DU患者随机分成2组,治疗组82例,用呋喃唑酮200mg、乐得胃2片每天三次,法莫替丁20mg早晚各一次治疗2周:对照组74例,用羟氨苄青霉素500mg、胶体果胶铋100mg(以Bi计)每天三次,奥美拉唑40mg每天早晨一次治疗2周,疗程结束时复查胃镜观察溃疡愈合情况,疗程结束后4周取胃粘膜检查幽门螺杆菌(HP),观察HP根除情况。结果:治疗组和对照组对DU有效率分别为93.6％和94.5％,无统计学差异(P>0.05),HP根除率分别为82.3％和95.7％,对照组明显高于治疗组(P<0.01);治疗组2例出现白细胞轻度降低(3.5×10~9/L),对照组1例ALT轻度升高,治疗结束后均恢复,余无严重不良反应。呋喃唑酮、乐得胃、法莫替丁联合治疗DU,虽然HP根除率稍低,但经济、安全、有效,尤其适用于低收入患者。  相似文献   

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Polymerase chain reaction (PCR) and gel electrophoresis have become common techniques used in undergraduate molecular and cell biology labs. Although students enjoy learning these techniques, they often cannot fully comprehend and analyze the outcomes of their experiments because of a disconnect between concepts taught in lecture and experiments done in lab. Here we report the development and implementation of novel exercises that integrate the biological concepts of DNA structure and replication with the techniques of PCR and gel electrophoresis. Learning goals were defined based on concepts taught throughout the cell biology lab course and learning objectives specific to the PCR and gel electrophoresis lab. Exercises developed to promote critical thinking and target the underlying concepts of PCR, primer design, gel analysis, and troubleshooting were incorporated into an existing lab unit based on the detection of genetically modified organisms. Evaluative assessments for each exercise were aligned with the learning goals and used to measure student learning achievements. Our analysis found that the exercises were effective in enhancing student understanding of these concepts as shown by student performance across all learning goals. The new materials were particularly helpful in acquiring relevant knowledge, fostering critical-thinking skills, and uncovering prevalent misconceptions.  相似文献   

10.
Two types of inquiry have been at the heart of recent discussions of systematic evidence in educational policy and practice: randomized field trials (RFTs) and nationally representative surveys. We argue that integrating these 2 modes of inquiry has the potential to strengthen the evidence base for school reform. In particular, national surveys can help determine the focus of RFTs, by identifying factors that place schools at risk of poor achievement or buffer schools from risk. In addition, surveys can provide data on the prevalence of interventions identified as effective in RFTs and the conditions under which the interventions are being implemented. Finally, RFTs and surveys, taken together, can provide information on ways of improving the coherence of the set of interventions used at the school level.  相似文献   

11.
Abstract

A questionnaire designed to determine accessibility of a car was given to a Senior class of a suburban high school. Two grade-point averages were collected: the first before the students were legally able to drive, and the second after they had been legally able to drive for about one and one-half to two years. An IQ score was also collected. The subjects were divided into boys and girls. Car accessibility was divided into three categories: (1) no driver's license; (2) moderate accessibility; and (3) a group having maximum accessibility. It was concluded that the students' access to cars has no effect on the grade-point average over this period. This Is true even when their Hi is taken into account. It was determined that there is a differential pattern of access to cars by intellectual ability levels. Questions regarding the Interpretations of previous work seem justified.  相似文献   

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Objective: To investigate the evolution of pulmonary hypertension, the pathological changes of pulmonaryarteries, and the expression of VEGFmRNA and eNOSmRNA of pulmonary arterial endothelial cells in immature rabbitstreated with intratracheal bleomycin (BLM). Methods: Immature rabbits were divided into control and BLM group. Twoand four weeks after intratracheal normal saline or BLM injection, the systolic, diastolic and mean pulmonary arterypressure (PASP, PADP, MPAP) were measured by micro-catheter; the pathological changes and the expression ofVEGFmRNA and eNOSmRNA of endothelial cells in pulmonary arteries were evaluated by HE and in situ hybridization.Results: Two and four weeks after intratracheal injection of BLM, the PASP, PADP and MPAP increased 53%, 49%, 52%in 2 weeks, and 43%, 89%, 56% in 4 weeks; the wall thickness increased and the cavity in middle and small pulmonaryarteries became narrow; the Thickness Index (TI) and Area Index (AI) increased 25%, 14% in 2 weeks, and 22%, 24% in 4weeks; the level of VEGFmRNA and eNOSmRNA expression decreased 46%, 43% in 2 weeks, and 43%, 51% in 4 weeks.There was no significant difference between 2 weeks and 4 weeks BLM groups. Conclusion: The pulmonary artery pressurewas elevated, the thickness of wall increased and the cavity became narrow in middle and small pulmonary arteries, and thelevel of VEGFmRNA and eNOSmRNA expression in pulmonary arterial endothelial cells decreased in immature rabbitsafter 2 weeks and 4 weeks of intratracheal 4 U/kg BLM injection.  相似文献   

13.
In this experiment we studied the effect of goal setting on the strategies used to perform a block design task called SAMUEL. SAMUEL can measure many indicators, which are then combined to determine the strategies used by participants when solving SAMUEL problems. Two experimental groups were created: one group was given an explicit, difficult goal and the other was not given a goal. The two groups were comparable in their average visual–spatial ability. The results indicated no goal effect on the strategies, defined in terms of the combined indicators. However, the goal did have an effect on some of the indicators taken alone (total problem-solving time, total viewing time, and model-viewing frequency) but this was true only for subjects with a low cognitive ability. These findings demonstrate that setting a goal can have an effect on some strategy indexes used to assess performance on a visual-intelligence design task. This research has implications for defining intelligence-test instructions and educational requirements in school.  相似文献   

14.
Research Findings: Few studies have described parents' child care decision-making process, yet understanding how parents make child care choices is fundamental to developing effective services to promote the selection of high-quality care. This study used latent profile analysis to distinguish subgroups of low-income parents identified as having commonalities in the number of options, duration, and sources of information sought as part of their child care decision-making process. Study participants included 260 parents who participated in the baseline wave of the Minnesota Child Care Choices study, a longitudinal phone survey of welfare applicants. Two subgroups of parents were identified. The majority of parents (82%) made choices within 2 weeks and considered on average 2 arrangements. Fewer than half of these parents considered information from experts, public lists, or family members/friends when making a child care choice. The remaining 18% of the sample took on average 11 weeks to make a child care choice, considered on average 3 options, and relied more heavily on information from experts and family members/friends. Practice or Policy: Findings from this study have implications for the marketing of resource and referral counseling services, Quality Rating and Improvement Systems, and consumer education aimed at facilitating the selection of high-quality care.  相似文献   

15.
The purpose of this study was to investigate the influence of goal specificity and scaffolding on the programming performance and self‐regulation of elementary students engaged in learning game design. This study recruited 232 students for the experimental activities. Two levels of goal specificity were employed: specific and nonspecific. Structuring and problematizing scaffolds were also used to support students in the process of learning. Our results reveal the following: (1) nonspecific goals and structuring scaffolds led to superior comprehension of programming, (2) nonspecific goals with problematizing scaffolds led to better problem‐solving performance, (3) problematizing scaffolds were more effective than structuring scaffolds in the development of self‐regulation behavior, and (4) nonspecific goals were more effective than specific goals in the promotion of resource management associated with self‐regulation.  相似文献   

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Research Findings: This study investigated the prevalence of pedagogical questions posed by 27 early childhood educators as they interacted with infants in each of two naturally-occurring contexts: book-focused interactions and educator mediated play. The pedagogical questions expressed by educators to infants were coded as confirm (yes/no), specify (what, who, where, when) or explain (why, how) on the basis that these question types present infants with different opportunities to use their developing communication skills to provide information to others. We sought to determine associations between question use, activity context and educators’ qualification levels. Explain questions were used very rarely, while confirm and specify questions were more frequent, comprising 7.60% and 8.32% respectively of the messages expressed by educators to infants. A 2 (activity context) × 2 (qualification level) mixed factorial MANOVA, supplemented with post-hoc qualitative analyses, demonstrated that, in specific activity contexts, degree qualified early childhood teachers used pedagogical questioning in ways which differed from their less-qualified counterparts. Practice or policy: The findings provide much needed data on how educator questioning is used with children under two, how questioning affords context-specific language learning opportunities for infants in ECEC centres, and how educator qualifications may be implicated in these opportunities.  相似文献   

18.
Two new methods have been proposed to determine unexpected sum scores on sub-tests (testlets) both for paper-and-pencil tests and computer adaptive tests. A method based on a conservative bound using the hypergeometric distribution, denoted p, was compared with a method where the probability for each score combination was calculated using a highest density region (HDR). Furthermore, these methods were compared with the standardized log-likelihood statistic with and without a correction for the estimated latent trait value (denoted as l*z and lz, respectively). Data were simulated on the basis of the one-parameter logistic model, and both parametric and non-parametric logistic regression was used to obtain estimates of the latent trait. Results showed that it is important to take the trait level into account when comparing subtest scores. In a nonparametric item response theory (IRT) context, on adapted version of the HDR method was a powerful alterative to p. In a parametric IRT context, results showed that l*z had the highest power when the data were simulated conditionally on the estimated latent trait level.  相似文献   

19.
根据Genbank数据库已知的链霉菌的查尔酮合成酶基因的保守区设计chs基因特异简并引物,土壤总DNA为模板,利用PCR技术扩增得到该1条chs基因编码区,通过TA克隆、测序和同源比对及进化分析表明：该基因为放线菌来源chs基因．分别在该基因5＇末端和3’末端分别引入的限制酶NcoI和EcoRI酶切位点,利用上述2种限制酶分别酶切导入到psimple—T／chs载体和原核表达pET32a,凝胶回收目的片段后,将二者连接并转化大肠杆菌感受态细胞,转化子经菌液PCR筛选、双酶切鉴定后,3730测序结果表明,该基因全长编码区为1089bp,推测该基因编码全长为362个氨基酸残基,等电点（PI）为5．41、分子量为3965道尔顿含有cHs保守功能区的酸性蛋白质．分析表明,该基因与Streptomyceslividans来源的查尔酮合成酶RppA基因核苷酸相似性高达93％,氨基酸序列相似性高达87．70％．测序结果表明,该基因已经成功插入到pET32a载体中．  相似文献   

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