172 research outputs found
PPAR-δ in Vascular Pathophysiology
Peroxisome proliferator-activated receptors belong to the superfamily of ligand-dependent nuclear receptor transcription factors, which include three subtypes: PPAR-α, β/δ, and γ. PPAR-δ, play important roles in the regulation of cell growth and differentiation as well as tissue wound and repair. Emerging evidence has also demonstrated that PPAR-δ is implicated in lipids and glucose metabolism. Most recently, the direct effects of PPAR-δ on cardiovascular processes such as endothelial function and angiogenesis have also been investigated. Therefore, it is suggested that PPAR-δ may have critical roles in cardiovascular pathophysiology and is a potential target for therapeutic intervention of cardiovascular disorders such as atherosclerosis
Rosiglitazone Attenuated Endothelin-1-Induced Vasoconstriction of Pulmonary Arteries in the Rat Model of Pulmonary Arterial Hypertension via Differential Regulation of ET-1 Receptors
Pulmonary arterial hypertension (PAH) is a fatal disease characterized by a progressive increase in pulmonary arterial pressure leading to right ventricular failure and death. Activation of the endothelin (ET)-1 system has been demonstrated in plasma and lung tissue of PAH patients as well as in animal models of PAH. Recently, peroxisome proliferator-activated receptor γ (PPARγ) agonists have been shown to ameliorate PAH. The present study aimed to investigate the mechanism for the antivasoconstrictive effects of rosiglitazone in response to ET-1 in PAH. Sprague-Dawley rats were exposed to chronic hypoxia (10% oxygen) for 3 weeks. Pulmonary arteries from PAH rats showed an enhanced vasoconstriction in response to ET-1. Treatment with PPARγ agonist rosiglitazone (20 mg/kg per day) with oral gavage for 3 days attenuated the vasocontractive effect of ET-1. The effect of rosiglitazone was lost in the presence of L-NAME, indicating a nitric oxide-dependent mechanism. Western blotting revealed that rosiglitazone increased ETBR but decreased ETAR level in pulmonary arteries from PAH rats. ETBR antagonist A192621 diminished the effect of rosiglitazone on ET-1-induced contraction. These results demonstrated that rosiglitazone attenuated ET-1-induced pulmonary vasoconstriction in PAH through differential regulation of the subtypes of ET-1 receptors and, thus, provided a new mechanism for the therapeutic use of PPARγ agonists in PAH
The Nature of High Soil Radioactivity in Chinese Province Guangdong
Soil is a basic component of biosphere and its important natural resource. The article deals with the analysis of soil radioactivity in Chinese province Guangdong. In the course of the analysis, it was stated that highly radioactive soil of China had been formed due to deep chemical weathering of highly radioactive potassium granites. High uranium and thorium contents in them are caused by specific conditions of weathering crust formation and subsequent pedogenesis. High dose loads for a man are formed in the development fields of such rock types
The Nature of High Soil Radioactivity in Chinese Province Guangdong
Soil is a basic component of biosphere and its important natural resource. The article deals with the analysis of soil radioactivity in Chinese province Guangdong. In the course of the analysis, it was stated that highly radioactive soil of China had been formed due to deep chemical weathering of highly radioactive potassium granites. High uranium and thorium contents in them are caused by specific conditions of weathering crust formation and subsequent pedogenesis. High dose loads for a man are formed in the development fields of such rock types
Taxonomic analysis of asteroids with artificial neural networks
We study the surface composition of asteroids with visible and/or infrared
spectroscopy. For example, asteroid taxonomy is based on the spectral features
or multiple color indices in visible and near-infrared wavelengths. The
composition of asteroids gives key information to understand their origin and
evolution. However, we lack compositional information for faint asteroids due
to limits of ground-based observational instruments. In the near future, the
Chinese Space Survey telescope (CSST) will provide multiple colors and
spectroscopic data for asteroids of apparent magnitude brighter than 25 mag and
23 mag, respectively. For the aim of analysis of the CSST spectroscopic data,
we applied an algorithm using artificial neural networks (ANNs) to establish a
preliminary classification model for asteroid taxonomy according to the design
of the survey module of CSST. Using the SMASS II spectra and the Bus-Binzel
taxonomy system, our ANN classification tool composed of 5 individual ANNs is
constructed, and the accuracy of this classification system is higher than 92
%. As the first application of our ANN tool, 64 spectra of 42 asteroids
obtained in 2006 and 2007 by us with the 2.16-m telescope in the Xinglong
station (Observatory Code 327) of National Astronomical Observatory of China
are analyzed. The predicted labels of these spectra using our ANN tool are
found to be reasonable when compared to their known taxonomic labels.
Considering the accuracy and stability, our ANN tool can be applied to analyse
the CSST asteroid spectra in the future.Comment: 10 pages,8 figures,accepted by AJ for publicatio
Peroxisome Proliferator-Activated Receptor γ
Lipid phosphate phosphohydrolase 1 (LPP1), a membrane ectophosphohydrolase regulating the availability of bioactive lipid phosphates, plays important roles in cellular signaling and physiological processes such as angiogenesis and endothelial migration. However, the regulated expression of LPP1 remains largely unknown. Here, we aimed to examine a role of peroxisome proliferator-activated receptor γ (PPARγ) in the transcriptional control of LPP1 gene expression. In human umbilical vein endothelial cells (HUVECs), quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) demonstrated that activation of PPARγ increased the mRNA level of LPP1. Chromatin immunoprecipitation assay showed that PPARγ binds to the putative PPAR-responsive elements (PPREs) within the 5′-flanking region of the human LPP1 gene. Genomic fragment containing 1.7-kilobase of the promoter region was cloned by using PCR. The luciferase reporter assays demonstrated that overexpression of PPARγ and rosiglitazone, a specific ligand for PPARγ, could significantly upregulate the reporter activity. However, site-directed mutagenesis of the PPRE motif abolished the induction. In conclusion, our results demonstrated that PPARγ transcriptionally activated the expression of LPP1 gene in ECs, suggesting a potential role of PPARγ in the metabolism of phospholipids
CaS: A key medium for C-O-S-Ca cycles in Earth
Oldhamite (CaS) is a rare mineral, which is only observed naturally in
enstatite meteorites.No occurrence of CaS has been documented from other groups
of meteorites and terrestrial samples. However, in experiments at 1.5 GPa/1510
K and 0.5 GPa/1320 K, when the lgfo2 is lower than -10.57 (FMQ-0.52), CaS was
produced in this study by a two-melt mechanism involving the reaction between
molten pyrrhotite-pentlandite-bearing orthopyroxenite and molten CaCO3. CaS can
be easily oxidized to form CaSO4 or hydrolyzed to produce calcium hydroxide,
which may explain why it has never been found in geological samples from Earth.
We speculate that part of the anhydrite and gypsum in black smokers along
mid-ocean ridges are related to the oxidation or hydrolysis of CaS in the
underlying mantle. CaS can be produced when the Siberian mantle plume intruded
into the lithosphere.Comment: The third versio
PPARgene: A Database of Experimentally Verified and Computationally Predicted PPAR Target Genes
The peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors of the nuclear receptor superfamily. Upon ligand binding, PPARs activate target gene transcription and regulate a variety of important physiological processes such as lipid metabolism, inflammation, and wound healing. Here, we describe the first database of PPAR target genes, PPARgene. Among the 225 experimentally verified PPAR target genes, 83 are for PPARα, 83 are for PPARβ/δ, and 104 are for PPARγ. Detailed information including tissue types, species, and reference PubMed IDs was also provided. In addition, we developed a machine learning method to predict novel PPAR target genes by integrating in silico PPAR-responsive element (PPRE) analysis with high throughput gene expression data. Fivefold cross validation showed that the performance of this prediction method was significantly improved compared to the in silico PPRE analysis method. The prediction tool is also implemented in the PPARgene database
- …