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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Validation Of A Novel Hypothesis Of Generating Foam Cells By Its Use To Study Reverse Cholesterol Transport

Sengupta, Bhaswati 01 January 2014 (has links)
Generation of foam cells, an essential step for reverse cholesterol transport (RCT) studies, uses the technique of receptor dependent macrophage loading with radiolabeled acetylated Low Density Lipoprotein (Ac-LDL). In this study, we used the ability of a biologically relevant detergent molecule, Lysophosphatidylcholine (Lyso PtdCho), to form mixed micelles with cholesterol or cholesteryl ester (CE) to generate macrophage foam cells. Fluorescent or radiolabelled cholesterol / Lyso PtdCho mixed micelles were prepared and incubated with RAW 264.7 or mouse peritoneal macrophages. Results showed that such micelles were quite stable at 4°C and retained the solubilized cholesterol during one month storage. Macrophages incubated with cholesterol or CE (unlabeled, fluorescently labeled or radiolabeled) / Lyso PtdCho mixed micelles accumulated CE as documented by microscopy, lipid staining, labeled oleate incorporation, and by thin layer chromatography (TLC). Such foam cells unloaded cholesterol when incubated with high density lipoprotein (HDL) and not with oxidized HDL (Ox-HDL). We propose that stable cholesterol or CE / Lyso PtdCho micelles would offer advantages over existing methods. Oxidative stress is associated with heart failure (HF). Previously our research group observed that the patients with low left-ventricular ejection fraction showed accumulation of high level of oxidized LDL (Ox-LDL) when compared with the heart failure patients with normal range of ejection fraction (EF). HDL is known to be atheroprotective and one of its important antioxidative functions is to protect LDL from oxidative modifications. However, HDL itself undergoes oxidation and Ox-HDL becomes functionally poor. It is expected to have a diminished ability to promote reverse cholesterol transport. Therefore, it was hypothesized that the quality of HDL present in the patients with EF would more compromised than those present in the patients with normal EF. Functionality of HDL was evaluated by measuring its cholesterol efflux capacity from foam cells generated in vitro. Functionality of HDL, which is strongly related to the oxidative modifications of HDL was further estimated by measuring paraoxonase 1 (PON1) enzyme activity associated with HDL. Higher the PON1 activity and RCT ability, better is the functionality of HDL.
22

Molecular Modulation of a-Subunit VISIT-DG Sequence Residue Asp-350 in the Catalytic sites of <em>Escherichia coli</em> ATP Synthase.

Jonnalagadda, Sneha R 01 May 2011 (has links)
ATP Synthase is the fundamental means of cellular energy production in animals, plants, and almost all microorganisms. In order to understand the mechanism of ATP catalysis, critical amino acid residues involved in Pi binding have to be identified. The αVISIT-DG sequence at the interface of α/β subunits that contains residues from 345-351 is highly conserved and αAsp-350 has been chosen because of its negative charge side chain and its close proximity (~2.8 Å) to the known phosphate binding residue αArg-376. The mutant's αD350R, αD350Q, αD350A, αR376A/D, and αG351R/A/D were generated by site directed mutagenesis and several biochemical assays were performed on them to understand the role played by the amino acid residues in Pi binding. Biochemical results suggest that αD350 may be involved in catalysis of ATP synthase and play an important role in Pi binding, whereas αG351 may be involved only in the structural integrity.
23

跨國新產品銷售預測模式之研究-以電影為例 / Models Comparing for Forecasting Sales of a New Cross-National Product - The Case of American Hollywood Motion Pictures

李心嵐, Lee, Hsin-Lan Unknown Date (has links)
現今市場競爭愈來愈激烈,迫使廠商紛紛至海外尋求產品消費市場,在跨國銷售的背景之下,需要有更多可以確定國家選擇、預測銷售及估計需求的方法。而其中可以滿足這些需求的方法之中,就是研究產品跨國擴散型態,藉以瞭解後進國家與領先國家中新產品如何擴散且會如何互相影響 (Douglas and Craig, 1992)。 在眾多的跨國產品中,本研究選擇好萊塢電影做為實證分析的對象。 經由集群分析,本研究發現(一)台灣高首週票房且口碑佳的電影,會遇到假日人潮、有很高的美國總票房、以及很高的美國首週票房;(二)美國影片在美國及台灣映演的每週票房趨勢有差異存在;(三)片商沒有做好影片在台灣映演的檔期歸劃;(四)三群電影中,在影片類型沒有明顯地區別。 經由十二個新產品銷售預測模型的建立:對數線性迴歸模式(LN-Regression Model)(不考慮新產品領先國擴散經驗)(以OLS估計)、卜瓦松迴歸模式(Poisson Regression Model) (不考慮新產品領先國擴散經驗)(以MLE估計)、負二項分配迴歸模式(Negative Binomial Distribution Regression Model) (不考慮新產品領先國擴散經驗)(以MLE估計)、Exponential Decay模式(以OLS估計)+迴歸方程式體系(不考慮新產品領先國擴散經驗)(以SUR估計)、Exponential Decay模式(以OLS估計)+迴歸方程式體系(考慮新產品領先國擴散經驗)(以SUR估計)、Exponential Decay模式+層級貝氏迴歸模式(考慮新產品領先國擴散經驗)、Bass連續型擴散模式(以NLS估計)+迴歸方程式體系(不考慮新產品領先國擴散經驗(以SUR估計)、Bass連續型擴散模式(以NLS估計)+迴歸方程式體系(考慮新產品領先國擴散經驗(以SUR估計)、Bass離散型擴散模式(以OLS估計)+迴歸方程式體系(不考慮新產品領先國擴散經驗)(以SUR估計)、Bass離散型擴散模式(以OLS估計)+迴歸方程式體系(考慮新產品領先國擴散經驗)(以SUR估計)、層級貝氏BASS離散型擴散模式+迴歸方程式體系(不考慮新產品領先國擴散經驗)(以SUR估計)、層級貝氏BASS離散型擴散模式+迴歸方程式體系(考慮新產品領先國擴散經驗)(以SUR估計)。本研究發現:(一)在考慮影響後進國的新產品擴散速度時,領先國的擴散經驗為絕對必要的考慮因子;(二)必須使用Bass連續型擴散模式做為建構新產品銷售預測模型的基礎;(三)必須使用Bass連續型擴散模式的NLS估計法估計Bass模型的創新係數p、模仿係數q及市場潛量m。

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