1,720,971 research outputs found
Growth Inhibition and Cell Cycle Arrest in Human Hepatoma HepG2 Cells by Protein HM-3 from Hypsizigus marmoreus
No full text肝癌為近年來國人癌症死因中第二位，目前常用的治療方法有手術切除、肝臟移植、栓塞治療以及化學藥物治療等，但皆有其侷限性或副作用；因此，由天然物開發有效之抗癌藥物已成為重要的課題。鴻喜菇 (Hypsizigus marmoreus) 為低熱量、低脂肪且營養價值高的食用菇，目前研究結果顯示其具有抗腫瘤、抗真菌、抗氧化等功能。本研究將鴻喜菇以 40~80% 飽和度之硫酸銨沉澱得蛋白質粗萃物，再以陰離子交換樹脂 DEAE-Sepharose CL-6B 經連續鹽梯度或階梯鹽梯度溶離收集樣品。以 0~1 M連續鹽梯度所得樣品 HM-3 及階梯梯度 0.2 與 0.4 M 鹽濃度溶離之樣品 ( fraction Ⅰ、Ⅱ) 對 HepG2 進行生長抑制測試，經 50 µg/ml 之 HM-3 處理 12 及 24 小時得到的生長抑制率分別為 87.41% 及 88.25%，且生長抑制具有濃度效應。以 50 µg/ml 之 fraction Ⅰ 對 HepG2 處理 12 及 24 hr 的抑制率分別為 24.41% 與 19.44%，而 fraction Ⅱ 則無抑制效果。階梯梯度樣品中以 fraction Ⅰ 抑制效果為佳，但仍較 HM-3 差，故後續探討生長抑制機制皆以 HM-3 為樣品。由流式細胞儀分析細胞週期結果顯示，以 HM-3 處理 24小時，會使 HepG2 出現細胞週期停滯 (cell cycle arrest)，當濃度由 0 提升至 200 µg/ml，G1 phase 比例由 54.35% 提高至 69.08%，但並無細胞凋亡之現象。以瓊脂糖膠體電泳檢測 DNA 完整性，也未觀察到細胞凋亡特徵之ㄧ的 DNA 片段化。利用西方墨點法檢測 G1 細胞週期停滯相關蛋白 p53、p21、p27、cyclin A2、cyclin D1、cyclin E1 及 CDK2 之表現，發現隨處理濃度提高，p53 及 p21 表現量皆有增加的現象，p21 表現量與控制組相比具顯著差異。cyclin E1 表現量與控制組相比有顯著下降的現象，而 p27、cyclin A2、cyclin D1 及 CDK2 表現量則無明顯變化。根據以上結果推測，HM-3 能抑制 HepG2 生長，並可能透過活化 p53 與 p21 而抑制 cyclin E1 之表現，使其細胞週期停留在 G1 phase。The mortality rate of hepatocellular carcinoma in all cancer mortality ranks second in Taiwan. There are some common treatments against this disease such as surgical resection, liver transplantation, embolization and chemotherapy. Although these treatments have been carried out for many years, they still have limitations and side effects. Therefore, exploration of effective chemotherapeutic agents from natural food is urgently needed. Hypsizigus marmoreus is a low-calorie, low-fat and high protein concent mushroom. A number of bioactive molecules including antitumor, antifungal and antioxidant substances have been identified from this mushroom. In this research, proteins in H. marmoreus were precipitated by 40~80% saturated ammonium sulfate. DEAE-Sepharose CL-6B ion exchange chromatography was used subsequently, and eluted by 0~1 M NaCl continuous or stepwise gradient. Fraction isolated by continuous gradient named HM-3, and eluted by 0.2 or 0.4 M NaCl stepwise gradient named fraction Ⅰ or Ⅱ. HM-3 at a concentration of 50 µg/ml strongly inhibited the growth of HepG2 cells by 87.41% and 88.25% for 12 and 24 hr respectively. HM-3 inhibited the growth of HepG2 cells in a concentration-dependent manner. Cells were incubated with 50 µg/ml fractionⅠ or Ⅱ for 12 and 24 hr, and results showed that fractionⅠinhibited the growth of HepG2 cells by 24.41% and 19.44%. Fraction Ⅱ had no obvious growth inhibition. Above results indicated that HM-3 had better growth inhibition than others, so we chose HM-3 to investigate the mechanism of growth inhibition. G1 phase arrest was observed by flow cytometry when cells were incubated with HM-3 for 24 hr. G1 phase percentage ranged from 54.35% to 69.08% when concentration increased to 200 µg/ml from 0 µg/ml, but no apoptosis was observed. DNA ladder was not observed by agarose gel electrophoresis. Western blotting analysis showed the expression of p53 and p21 increased in HepG2 cells with the increasing concentration of HM-3. Obvious decrease in cyclin E1 was observed and no apparent change in p27, cyclin A2, cyclin D1 and CDK2. According to these results, HM-3 might induce growth inhibition by activating p53 and p21, then inactivating cyclin E1, causing G1 phase cell cycle arrest in HepG2 cells
Cell Capture and Separation Using Dielectrophoresis and Microfluidics
No full text本論文工作乃利用微流及介電泳技術，設計並製作一於流動液體中捕捉與分離粒子(含細胞)的微流裝置。該裝置在一微流道頂壁建有凹槽，在凹槽上下游流道底壁建有電極，以産生負介電泳力選擇性地將具特定Kr值(柯莫氏因子的實部)的粒子推入凹槽内、具其他Kr值的粒子則被流動液體帶往下游，而得以將不同介電特性的粒子分離。此裝置為他人在文獻中所提出者，本文將該裝置修改使能對欲分離的兩種粒子分别精確計數、而能算出對目標粒子在給定參數下的捕捉率及分離純度，所以本文所發展裝置能用於探取分離不同粒子所需的適當操作參數、而是此類以粒子固有物理特性作分離依據的裝置所必需的。就聚苯乙烯(PS)粒子與癌細胞(含肺癌細胞CL1-0與CL1-5及腸癌細胞Colo205)的分離，在操作頻率1MHz、流量40ul/hr以下時，二者可100%分離；就CL1-0與Colo205在導電度0.11S/m的溶液中，在流量30ul/hr及操作頻率為70kHz時分離率可達80%以上。本文亦對所提出裝置在幾何及操作參數上作了數值及實驗分析。A device for selective particle capture and separation using microfluidics and dielectrophoresis was developed in the thesis. The device is a micro channel with grooves built on its ceiling. Electrodes are built on the bottom surface of the device on both the upstream and downstream sides of the groove. Negative dielectrophoretic force is exerted on the test particle when it passes through the electrode gap. Particles with selected Kr (the real part of the Clausius-Mossotti factor) will be pushed into the channel and are thus captured. Other particles with different Kr will be carried downstream, and thus particles with different dielectric properties are separated. The device was reported in the literature, but here we propose a modify version of the device such that the two particles to be separated can be counted, and thus the capture rate and purity of separation can be evaluated accurately. Therefore, the modified device proposed here is capable of determining suitable operation parameters for a given separation, which is necessary for a separating device based on the intrinsic physical properties of particles. As for the separation of polystyrene particles and cancer cells (including the lung cancer cells CL1-0 and CL1-5, and the colorectal cancer cells Colo205), 100% can be separated under a frequency 1 MHz and a background flow rate below 40ul/hr. 80% separation can be achieved for the mixture of CL1-0 and Colo205 in a medium with conductivity 0.11S/m, at a flow rate 30ul/hr and frequency 70kHz. The geometric and operation parameters of the device were also studied numerically and experimentally
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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