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Search Results: 1 - 10 of 1815 matches for " Maryam Rakhshandehroo "
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Peroxisome Proliferator-Activated Receptor Alpha Target Genes
Maryam Rakhshandehroo,Bianca Knoch,Michael Müller,Sander Kersten
PPAR Research , 2010, DOI: 10.1155/2010/612089
Abstract: The peroxisome proliferator-activated receptor alpha (PPAR ) is a ligand-activated transcription factor involved in the regulation of a variety of processes, ranging from inflammation and immunity to nutrient metabolism and energy homeostasis. PPAR serves as a molecular target for hypolipidemic fibrates drugs which bind the receptor with high affinity. Furthermore, PPAR binds and is activated by numerous fatty acids and fatty acid-derived compounds. PPAR governs biological processes by altering the expression of a large number of target genes. Accordingly, the specific role of PPAR is directly related to the biological function of its target genes. Here, we present an overview of the involvement of PPAR in lipid metabolism and other pathways through a detailed analysis of the different known or putative PPAR target genes. The emphasis is on gene regulation by PPAR in liver although many of the results likely apply to other organs and tissues as well. 1. Introduction Nutrient metabolism and energy homeostasis are tightly controlled by numerous regulatory systems involving specific transcription factors. The peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the superfamily of nuclear hormone receptors and play an important role in nutrient homeostasis [1–3]. Three different PPAR subtypes are known: and All PPARs share the same molecular mode of action via formation of heterodimers with the nuclear receptor RXR, followed by binding to specific DNA-response elements in target genes known as peroxisome proliferator response elements (PPREs). PPREs are characterized by a common core sequence consisting of a direct repeat of the consensus sequence AGGTCA interspaced by a single nucleotide [1, 4]. Expression of and is found ubiquitously, whereas is mainly expressed in adipose tissue, macrophages, and colon [5, 6]. Activation of transcription by PPARs is dependent on a number of different steps including ligand binding to PPAR, binding of PPAR to the target gene, removal of corepressors and recruitment of coactivators, remodeling of the chromatin structure, and finally facilitation of gene transcription [7]. This paper will focus exclusively on ? was first discovered in the early 1990s and since then has been identified as the master regulator of hepatic lipid metabolism [8]. In addition, has been shown to govern glucose metabolism, lipoprotein metabolism, liver inflammation, amino acid metabolism, and hepatocyte proliferation (specifically in rodents). Synthetic agonists of lower plasma triglycerides
Comparative Analysis of Gene Regulation by the Transcription Factor PPARα between Mouse and Human
Maryam Rakhshandehroo, Guido Hooiveld, Michael Müller, Sander Kersten
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006796
Abstract: Background Studies in mice have shown that PPARα is an important regulator of hepatic lipid metabolism and the acute phase response. However, little information is available on the role of PPARα in human liver. Here we set out to compare the function of PPARα in mouse and human hepatocytes via analysis of target gene regulation. Methodology/Principal Findings Primary hepatocytes from 6 human and 6 mouse donors were treated with PPARα agonist Wy14643 and gene expression profiling was performed using Affymetrix GeneChips followed by a systems biology analysis. Baseline PPARα expression was similar in human and mouse hepatocytes. Depending on species and time of exposure, Wy14643 significantly induced the expression of 362–672 genes. Surprisingly minor overlap was observed between the Wy14643-regulated genes from mouse and human, although more substantial overlap was observed at the pathway level. Xenobiotics metabolism and apolipoprotein synthesis were specifically regulated by PPARα in human hepatocytes, whereas glycolysis-gluconeogenesis was regulated specifically in mouse hepatocytes. Most of the genes commonly regulated in mouse and human were involved in lipid metabolism and many represented known PPARα targets, including CPT1A, HMGCS2, FABP1, ACSL1, and ADFP. Several genes were identified that were specifically induced by PPARα in human (MBL2, ALAS1, CYP1A1, TSKU) or mouse (Fbp2, lgals4, Cd36, Ucp2, Pxmp4). Furthermore, several putative novel PPARα targets were identified that were commonly regulated in both species, including CREB3L3, KLF10, KLF11 and MAP3K8. Conclusions/Significance Our results suggest that PPARα activation has a major impact on gene regulation in human hepatocytes. Importantly, the role of PPARα as master regulator of hepatic lipid metabolism is generally well-conserved between mouse and human. Overall, however, PPARα regulates a mostly divergent set of genes in mouse and human hepatocytes.
Allele Compensation in Tip60+/? Mice Rescues White Adipose Tissue Function In Vivo
Yuan Gao, Nicole Hamers, Maryam Rakhshandehroo, Ruud Berger, John Lough, Eric Kalkhoven
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098343
Abstract: Adipose tissue is a key regulator of energy homestasis. The amount of adipose tissue is largely determined by adipocyte differentiation (adipogenesis), a process that is regulated by the concerted actions of multiple transcription factors and cofactors. Based on in vitro studies in murine 3T3-L1 preadipocytes and human primary preadipocytes, the transcriptional cofactor and acetyltransferase Tip60 was recently identified as an essential adipogenic factor. We therefore investigated the role of Tip60 on adipocyte differentiation and function, and possible consequences on energy homeostasis, in vivo. Because homozygous inactivation results in early embryonic lethality, Tip60+/? mice were used. Heterozygous inactivation of Tip60 had no effect on body weight, despite slightly higher food intake by Tip60+/? mice. No major effects of heterozygous inactivation of Tip60 were observed on adipose tissue and liver, and Tip60+/? displayed normal glucose tolerance, both on a low fat and a high fat diet. While Tip60 mRNA was reduced to 50% in adipose tissue, the protein levels were unaltered, suggesting compensation by the intact allele. These findings indicate that the in vivo role of Tip60 in adipocyte differentiation and function cannot be properly addressed in Tip60+/? mice, but requires the generation of adipose tissue-specific knock out animals or specific knock-in mice.
Comprehensive Analysis of PPAR-Dependent Regulation of Hepatic Lipid Metabolism by Expression Profiling
Maryam Rakhshandehroo,Linda M. Sanderson,Merja Matilainen,Rinke Stienstra,Carsten Carlberg,Philip J. de Groot,Michael Müller,Sander Kersten
PPAR Research , 2007, DOI: 10.1155/2007/26839
Abstract: PPARα is a ligand-activated transcription factor involved in the regulation of nutrient metabolism and inflammation. Although much is already known about the function of PPARα in hepatic lipid metabolism, many PPARα-dependent pathways and genes have yet to be discovered. In order to obtain an overview of PPARα-regulated genes relevant to lipid metabolism, and to probe for novel candidate PPARα target genes, livers from several animal studies in which PPARα was activated and/or disabled were analyzed by Affymetrix GeneChips. Numerous novel PPARα-regulated genes relevant to lipid metabolism were identified. Out of this set of genes, eight genes were singled out for study of PPARα-dependent regulation in mouse liver and in mouse, rat, and human primary hepatocytes, including thioredoxin interacting protein (Txnip), electron-transferring-flavoprotein β polypeptide (Etfb), electron-transferring-flavoprotein dehydrogenase (Etfdh), phosphatidylcholine transfer protein (Pctp), endothelial lipase (EL, Lipg), adipose triglyceride lipase (Pnpla2), hormone-sensitive lipase (HSL, Lipe), and monoglyceride lipase (Mgll). Using an in silico screening approach, one or more PPAR response elements (PPREs) were identified in each of these genes. Regulation of Pnpla2, Lipe, and Mgll, which are involved in triglyceride hydrolysis, was studied under conditions of elevated hepatic lipids. In wild-type mice fed a high fat diet, the decrease in hepatic lipids following treatment with the PPARα agonist Wy14643 was paralleled by significant up-regulation of Pnpla2, Lipe, and Mgll, suggesting that induction of triglyceride hydrolysis may contribute to the anti-steatotic role of PPARα. Our study illustrates the power of transcriptional profiling to uncover novel PPARα-regulated genes and pathways in liver.
Three Dimensional Seepage Analyses in Mollasadra Dam after Its Impoundments
GR Rakhshandehroo, M Vaghefi, ARH Zadeh
Journal of Applied Sciences and Environmental Management , 2011,
Abstract: Mollasadra dam is an earth fill dam with a clayey core and a height of 72 m from river bed, constructed on Kor River. pore water pressure in the dam was investigated following its construction and first and second impoundments. The dam was modeled by a finite element mesh. After the first and second dam impoundments, the overall trend in monitored pore water pressure was well modeled by the transient analysis. The result showed the six month time period between impoundments was long enough for the pore water pressure to reach equilibrium everywhere throughout the core, except where considerable initial constructioninduced pore water pressure was observed. High values of construction-induced pore water pressure at elevation 2050 m did not dissipate completely during the 6 month period of almost constant reservoir level (el. 2098.3 m) and the pore pressures were still at the transient state throughout the core. Therefore, it was concluded that pore pressures in the core of earth fill dams may not achieve steady state conditions even several months after the dam construction and impoundments.
The Effects of Collective Leadership on Student Achievement and Teacher Instruction  [PDF]
Maryam Awadh
Open Journal of Leadership (OJL) , 2018, DOI: 10.4236/ojl.2018.74015
Abstract: In the past, the leadership position primarily involved how leaders handled their role. The notion of collective leadership is significant for constructing the educational community and sustaining inclusive collective participation. This paper shows the framework of the leadership, and comprehensively addresses the ways in which leaders have a direct impact on classroom instruction and student learning outcomes. The study outlines how leadership abilities are linked to student achievement and illustrates how principals and instructional leaders are the central figures of this leadership. The study found the ways in which leaders indirectly influence student achievement through their impact on teacher motivation and work conditions, and whether teachers’ knowledge and skills have an effect on student achievement in the educational system. The influences of collective leadership on classroom instruction were examined, including ways in which changes in instruction could influence both teachers and students.
Application of quartz crystal nanobalance in conjunction with a net analyte signal based method for simultaneous determination of leucine, isoleucine and valine  [PDF]
Maryam Shojaei, Abdolreza Mirmohseni, Maryam Farbodi
Journal of Biomedical Science and Engineering (JBiSE) , 2009, DOI: 10.4236/jbise.2009.27077
Abstract: The aim of the present investigation was to develop a biosensor for the detection of amino acids, Leucine, Isoleucine and Valine based on a quartz crystal nanobalance. leucine (Leu), isoleucine (Ile), and valine (Val) were selectively determined by quartz crystal nanobalance (QCN) sensor in conjunction with net analyte signal (NAS)-based method called HLA/GO. An orthogonal design was applied for the formation of calibration and prediction sets including Leu, Ile and Val compounds. The selection of the optimal time range involved the calculation of the net analyte sig-nal regression plot in any considered time window for each test sample. The searching of a region with maximum linearity of NAS regression plot (minimum error indicator) and minimum of PRESS value was carried out by applying a moving window strategy. On the base of obtained results, the differences on the adsorption profiles in the time range between 1 and 300 s were used to determine mixtures of compounds by HLA/GO method. The results showed that the method was successfully applied for the determina-tion of Leu, Ile and Val.
Effect of Surface Roughness and Materials Composition  [PDF]
Maryam Gharechahi, Horieh Moosavi, Maryam Forghani
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2012, DOI: 10.4236/jbnb.2012.324056
Abstract: In the mouth, biofilm formation occurs on all soft and hard surfaces. Microbial colonization on such surfaces is always preceded by the formation of a pellicle. The physicochemical surface properties of a pellicle are largely dependent on the physical and chemical nature of the underlying surface. Thus, the surface structure and composition of the underlying surface will influence on the initial bacterial adhesion. The aim of this review is to evaluate the influence of the surface roughness and the restorative material composition on the adhesion process of oral bacteria. Both in vitro and in vivo studies underline the importance of both variables in dental plaque formation. Rough surfaces will promote plaque formation and maturation. Candida species are found on acrylic dentures, but dentures coating and soaking of dentures in disinfectant solutions may be an effective method to prevent biofilm formation. Biofilms on gold and amalgam are thick, but with low viability. Glass-ionomer cement collects a thin biofilm with a low viability. Biofilms on composites cause surface deterioration, which enhances biofilm formation. Biofilms on ceramics are thin and highly viable.
The embryonic blood–CSF barrier has molecular elements for specific glucose transport and for the general transport of molecules via transcellular routes  [PDF]
Maryam Parvas, David Bueno
Advances in Bioscience and Biotechnology (ABB) , 2010, DOI: 10.4236/abb.2010.14041
Abstract: In vertebrates, early brain development takes place at the expanded anterior end of the neural tube, which is filled with embryonic cerebrospinal fluid (E-CSF). We have recently identified a transient blood–CSF barrier that forms between embryonic days E3 and E4 in chick embryos and that is responsible for the transport of proteins and control of E-CSF homeostasis, including osmolarity. Here we examined the presence of glucose transporter GLUT-1 as well the presence of caveolae-structural protein Caveolin1 (CAV-1) in the embryonic blood-CSF barrier which may be involved in the transport of glucose and of proteins, water and ions respectively across the neuroectoderm. In this paper we demonstrate the presence of GLUT-1 and CAV-1 in endothelial cells of blood vessels as well as in adjacent neuroectodermal cells, located in the embryonic blood–CSF barrier. In blood vessels, these proteins were detected as early as E4 in chick embryos and E12.7 in rat embryos, i.e. the point at which the embryonic blood–CSF barrier acquires this function. In the neuroectoderm of the embryonic blood-CSF barrier, GLUT-1 was also detected at E4 and E12.7 respectively, and CAV-1 was detected shortly thereafter in both experimental models. These experiments contribute to delineating the extent to which the blood–CSF embryonic barrier controls E-CSF composition and homeostasis during early stages of brain development in avians and mammals. Our results suggest the regulation of glucose transport to the E-CSF by means of GLUT-1 and also suggest a mechanism by which proteins are transported via transcellular routes across the neuroectoderm, thus reinforcing the crucial role of E-CSF in brain development.
Training Based Channel Estimation in MIMO-OFDM Systems  [PDF]
Maryam Imani, Hamidreza Bakhshi
Communications and Network (CN) , 2012, DOI: 10.4236/cn.2012.41008
Abstract: OFDM combined with the MIMO technique has become a core and attractive technology in future wireless communication systems and can be used to both improve capacity and quality of mobile wireless systems. Accurate and efficient channel estimation plays a key role in MIMO-OFDM communication systems, which is typically realized by using pilot or training sequences by virtue of low complexity and considerable performance. In this paper, we discuss some methods for channel estimation based training symbols in MIMO-OFDM systems. The results confirm the superiority of the represented methods over the existing ones in terms of bandwidth efficiency and estimation error.
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