1,912 research outputs found

    Functional pathway mapping analysis for hypoxia-inducible factors

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    Background: Hypoxia-inducible factors (HIFs) are transcription factors that play a crucial role in response to hypoxic stress in living organisms. The HIF pathway is activated by changes in cellular oxygen levels and has significant impacts on the regulation of gene expression patterns in cancer cells. Identifying functional conservation across species and discovering conserved regulatory motifs can facilitate the selection of reference species for empirical tests. This paper describes a cross-species functional pathway mapping strategy based on evidence of homologous relationships that employs matrix-based searching techniques for identifying transcription factorbinding sites on all retrieved HIF target genes. Results: HIF-related orthologous and paralogous genes were mapped onto the conserved pathways to indicate functional conservation across species. Quantitatively measured HIF pathways are depicted in order to illustrate the extent of functional conservation. The results show that in spite of the evolutionary process of speciation, distantly related species may exhibit functional conservation owing to conservative pathways. The novel terms OrthRate and ParaRate are proposed to quantitatively indicate the flexibility of a homologous pathway and reveal the alternative regulation of functional genes. Conclusion: The developed functional pathway mapping strategy provides a bioinformatics approach for constructing biological pathways by highlighting the homologous relationships between various model species. The mapped HIF pathways were quantitatively illustrated and evaluated by statistically analyzing their conserved transcription factor-binding elements

    The impact of stock market policy announcement on commodity prices and share prices

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    It has been an important issue to analyze the possible impact of macroeconomic effects, such as: exchange rate or interest rate, on the commodity prices since 1970s because of the tremendous volatility of commodity prices on the US. Thereafter, there are a lot of literature in agricultural economics relative to the empirical study. But the results of these literature are ambiguous. On the other hand, Blandchard (1981) incorporated the stock market into the traditional IS-LM model and discussed the interaction between stock market and economy. The financial sector plays an important role to affect the time path of commodity prices it cannot be ignored since agricultural industry is just one of sector among the whole economy. The main purpose of this article is to add the stock market into the two-goods economy. One is commodity product and the other is nonagricultural product. According the model including commodity market, nonagricultural product market, monetary market and stock market and under the assumptions of perfect substitutes between stock and bond and perfect foresight expectation, the effect of stock market policies, such as financing interest rate, financing ratio, on dynamics of commodity and share prices will be analyzed. The result shows that in the long run the impact of stock policies on commodity prices depends on the relative magnitudes of price effect of commodity and interest rate effect. While in the short run, whether share price overshooting or not it depends on the length of time between announcement and implement of policies.commodity prices, share prices, financing interest rate, financing ratio, dynamics

    In-Band Asymmetry Compensation for Accurate Time/Phase Transport over Optical Transport Network

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    The demands of precise time/phase synchronization have been increasing recently due to the next generation of telecommunication synchronization. This paper studies the issues that are relevant to distributing accurate time/phase over optical transport network (OTN). Each node and link can introduce asymmetry, which affects the adequate time/phase accuracy over the networks. In order to achieve better accuracy, protocol level full timing support is used (e.g., Telecom-Boundary clock). Due to chromatic dispersion, the use of different wavelengths consequently causes fiber link delay asymmetry. The analytical result indicates that it introduces significant time error (i.e., phase offset) within 0.3397 ns/km in C-band or 0.3943 ns/km in L-band depending on the wavelength spacing. With the proposed scheme in this paper, the fiber link delay asymmetry can be compensated relying on the estimated mean fiber link delay by the Telecom-Boundary clock, while the OTN control plane is responsible for processing the fiber link delay asymmetry to determine the asymmetry compensation in the timing chain

    股票政策宣告對農產品價格與股票價格的動態影響

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    It has been an important issue to analyze the possible impact of macroeconomic effects, such as: exchange rate or interest rate, on the commodity prices since 1970s because of the tremendous volatility of commodity prices on the US. Thereafter, there are a lot of literature in agricultural economics relative to the empirical study. But the results of these literature are ambiguous. On the other hand, Blandchard (1981) incorporated the stock market into the traditional IS-LM model and discussed the interaction between stock market and economy. The financial sector plays an important role to affect the time path of commodity prices it cannot be ignored since agricultural industry is just one of sector among the whole economy. The main purpose of this article is to add the stock market into the two-goods economy. One is commodity product and the other is nonagricultural product. According the model including commodity market, nonagricultural product market, monetary market and stock market and under the assumptions of perfect substitutes between stock and bond and perfect foresight expectation, the effect of stock market policies, such as financing interest rate, financing ratio, on dynamics of commodity and share prices will be analyzed. The result shows that in the long run the impact of stock policies on commodity prices depends on the relative magnitudes of price effect of commodity and interest rate effect. While in the short run, whether share price overshooting or not it depends on the length of time between announcement and implement of policies

    Accelerated induction of apoptosis in insect cells by baculovirus-expressed SARS-CoV membrane protein

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    AbstractIt has been shown that severe acute respiratory syndrome-associated coronavirus (SARS-CoV) 3a and 7a proteins, but not membrane (M) protein, induce apoptosis in mammalian cells. Upon expression of SARS-CoV M protein using the baculovirus/insect cell expression system, however, we found that the expressed M protein triggered accelerated apoptosis in insect cells, as characterized by rapid cell death, elevated cytotoxicity, cell shrinkage, nuclear condensation and DNA fragmentation. Conversely, the M protein expressed in mammalian cells did not induce apoptosis. This is the first report describing the induction of apoptosis by SARS-CoV M protein in animal cells and possible implications are discussed

    Sesamin: A Naturally Occurring Lignan Inhibits CYP3A4 by Antagonizing the Pregnane X Receptor Activation

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    Inconsistent expression and regulation of drug-metabolizing enzymes (DMEs) are common causes of adverse drug effects in some drugs with a narrow therapeutic index (TI). An important cytochrome, cytochrome P450 3A4 (CYP3A4), is predominantly regulated by a nuclear receptor, pregnane X receptor (PXR). Sesamin, a major lignan constituent in sesame seeds and oil, exhibits a variety of biological functions; however, the effect of sesamin on the modulation of CYP3A4 is not well understood. In this study, the effects of sesamin on the PXR-CYP3A4 pathway were characterized, as well as the underlying mechanisms of those effects. Sesamin potently attenuated CYP3A4 induction in a dose-dependent manner by blocking the activation of PXR. The PXR inducer-mediated inhibition of CYP3A4 was further evidenced by the ability of sesamin to attenuate the effects of several PXR ligands in the CYP3A4 reporter assay. Further mechanistic studies showed that sesamin inhibited PXR by interrupting the interacting with coregulators. These results may lead to the development of new therapeutic and dietary approaches to reduce the frequency of inducer-drug interaction. Sesamin was established as a novel inhibitor of PXR and may be useful for modulating DMEs expression and drug efficacies. Modification of CYP3A4 expression and activity by consumption of sesamin may have important implications for drug safety
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