Cryo-EM Structure and Biochemical Analysis of the Human Chemokine Receptor CCR8.

The C-C motif chemokine receptor 8 (CCR8) is a class A G-protein-coupled receptor that has emerged as a promising therapeutic target in cancer and autoimmune diseases. In the present study, we solved the cryo-electron microscopy (cryo-EM) structure of the human CCR8-Gi complex in the absence of a ligand at 2.58 Å. Structural analysis and comparison revealed that our apo CCR8 structure undergoes some conformational changes and is similar to that in the CCL1-CCR8 complex structure, indicating an active state. In addition, the key residues of CCR8 involved in the recognition of LMD-009, a potent nonpeptide agonist, were investigated by mutating CCR8 and testing the calcium flux induced by LMD-009-CCR8 interaction. Three mutants of CCR8, Y1133.32A, Y1724.64A, and E2867.39A, showed a dramatically decreased ability in mediating calcium mobilization, indicating their key interaction with LMD-009 and key roles in activation. These structural and biochemical analyses enrich molecular insights into the agonism and activation of CCR8 and will facilitate CCR8-targeted therapy.

Adaptive backstepping sliding mode control of permanent magnet spherical motor based on disturbance observer.

This paper proposes an adaptive backstepping sliding mode control method based on a nonlinear disturbance observer (NDO) to solve the problem that the tracking performance of the motion system of a permanent magnet spherical motor (PMSpM) is degraded due to the influence of external nonlinear disturbance. First, the dynamic model of the PMSpM under the compound interference is established. Second, an NDO and an adaptive backstepping sliding mode controller are designed to compensate for the external disturbances and modeling uncertainties, and the stability of the closed-loop system using the proposed method is confirmed through the Lyapunov theorem. Then, compared with the results of proportion differentiation control and conventional sliding mode control, the simulation results show that the proposed method can significantly reduce input signal chattering and improve the trajectory tracking performance of the PMSpM. Finally, experimental results are provided to validate the effectiveness of the proposed method.

The effects of the Promoting the Big and Quashing the Small Policy on pollutants from a coal power supply chain perspective.

China implemented the Promoting the Big and Quashing the Small Policy (PBQSP) in 2007 to alleviate air pollution due to coal-fired power plants (CFPPs). However, how the policy affected the air pollutant emissions remains poorly understood. We compared the air pollutant emissions between decommissioned and newly-built CFPPs under the PBQSP by developing a plant-level supply chain emission inventory model, taking Shandong, China's top provincial-level coal power producer, as the case area. The results indicated that compared to a 27.4% increase in electricity produced in Shandong from 2010 to 2014, the NOx, particulate matter (PM), Hg, and SO2 emissions disproportionately increased by 10.3%, 11.7%, 11.8% and 0.5%, respectively. It was found that the PBQSP policy has made great contribution to air pollution mitigation, as the supply chain emission intensities (emissions per kilowatt-hour) of NOX, PM, Hg and SO2 of the newly-built CFPPs are three-quarters, two-fifths, three-fifths, and four-fifths lower, respectively, than those of the decommissioned CFPPs. However, coal transport route changes caused an increase in NOX, PM, and SO2 emissions by 44.0%, 45.5%, and 55.6%, respectively, during the transportation stage, which offset the PBQSP overall mitigation effect. By building a comprehensive assessment framework for air pollutant control policies, our study provides insights for formulating coordinated mitigation measures for the pollutant-intensive industries, such as promoting efficient air pollutant control technologies including the spray dust suppression devices.

Impact of a Coal-Fired Power Plant Shutdown Campaign on Heavy Metal Emissions in China.

Recently, China has committed to decommissioning the heavy metal (HM) intensive coal-fired power plants (CFPPs), small units especially, yet a quantitative assessment for the impact on HM emissions remains poorly understood. This study, for the first time, compiles a plant-specific inventory for six HMs (Hg, As, Se, Pb, Cd, and Cr) avoided by CFPPs decommissioned in China during the 12th Five Year Plan period. The reduced HM amounts to 271.58 t (9.19 t Hg, 45.84 t As, 60.76 t Se, 85.30 t Pb, 1.74 t Cd, and 68.75 t Cr), accounting for 12.71% of the total emissions from all China's CFPPs in 2010. Small units which have low boiler efficiency and lack air pollutant control devices are more than tenfold HM-intensive as the large units. The detailed HM emission factors for each CFPP decommissioned in each provincial region are also identified. HM content in the coal consumed is a key parameter to determine their corresponding emission factors, while the capacity of decommissioned coal plants plays a decisive role in the reduced emissions. The high-resolution inventory not only verifies China's progress in alleviating HM pollution, but also provides basis for further investigation into HM relevant environmental and human health impact.

Effect of iron salt type and dosing mode on Fenton-based pretreatment of rice straw for enzymatic hydrolysis.

Fenton-based processes with four different iron salts in two different dosing modes were used to pretreat rice straw (RS) samples to increase their enzymatic digestibility. The composition analysis shows that the RS sample pretreated by the dosing mode of iron salt adding into H2O2 has a much lower hemicellulose content than that pretreated by the dosing mode of H2O2 adding into iron salt, and the RS sample pretreated by the chloride salt-based Fenton process has a much lower lignin content and a slightly lower hemicellulose content than that pretreated by the sulphate salt-based Fenton process. The higher concentration of reducing sugar observed on the RS sample with lower lignin and hemicellulose contents justifies that the Fenton-based process could enhance the enzymic hydrolysis of RS by removing hemicellulose and lignin and increasing its accessibility to cellulase. FeCl3·6H2O adding into H2O2 is the most efficient Fenton-based process for RS pretreatment.

Ultrasound-assisted alkaline pretreatment for enhancing the enzymatic hydrolysis of rice straw by using the heat energy dissipated from ultrasonication.

Rice straw samples were exposed to ultrasound-assisted alkaline (NaOH) pretreatment by using the heat energy dissipated from ultrasonication to increase their enzymatic digestibility for saccharification. The characterization shows that the pretreatment could selectively remove lignin and hemicellulose without degrading cellulose, and increase porosity and surface area of rice straw. The porosity, surface area and cellulose content of rice straw increased with the increasing concentration of NaOH used. The rice straw sample pretreated by using the heat energy dissipated from ultrasonication has a higher surface area and a lower crystallinity index value than that pretreated by using the external source of heating, and the amount of reducing sugar released from the former sample at 48h of enzymatic saccharification, which is about 3.5 times as large as that from the untreated rice straw sample (2.91vs. 0.85gL-1), is slightly larger than that from the latter sample (2.91vs. 2.73gL-1). The ultrasound-assisted alkaline pretreatment by using the heat energy dissipated from ultrasonication was proved to be a reliable and effective method for rice straw pretreatment.

Quercitrin treatment protects endothelial progenitor cells from oxidative damage via inducing autophagy through extracellular signal-regulated kinase.

Atherosclerosis is a disease resulting from impaired endothelial function, often caused by oxidant injury or inflammation. Endothelial progenitor cells (EPCs) play a critical role in repairing damaged endothelium and protecting against atherosclerosis. Quercitrin, a plant-derived flavonoid compound, displays antioxidant and anti-inflammatory activities. In this study, we showed that quercitrin treatment reduced the apoptosis of EPCs caused by oxidized low-density lipoprotein (ox-LDL) in a dose-dependent manner. Quercitrin improved tube formation, migration and adhesion of ox-LDL-treated EPCs. To determine the effect of quercitrin in vivo, EPCs treated with or without ox-LDL and quercitrin were locally injected into the ischemic hind limb muscle of nude mice. Those injected with EPCs treated with ox-LDL and quercitrin showed significantly increased local accumulation of EPCs, blood flow recovery and capillary density compared with the control and ox-LDL only groups. Furthermore, we showed that quercitrin enhanced autophagy and upregulated mitogen-activated protein kinase and ERK phosphorylation in a dose-dependent manner in vitro. Autophagy inhibitors, chloroquine and 3-methyladenine, abrogated quercitrin-enhanced autophagy caused by ox-LDL as evidenced by decreased numbers of branch points, migratory cells and adherent cells, and increased numbers of apoptotic cells. The ERK inhibitor PD98059 abrogated quercitrin-enhanced autophagy, as identified by decreased autophagosome formation and downregulated ERK phosphorylation. The inhibition of ERK did not affect the expression of Rac1, but enhanced phosphorylation of Akt. Quercitrin treatment also increased the expression of E-cadherin, and PD98059 abrogated the upregulation of E-cadherin induced by quercitrin. Our findings suggested that autophagy is a protective mechanism in EPCs exposed to oxidative damage. Quercitrin can promote autophagy through the activation of ERK and the ERK signaling pathway is therefore thought to play a pivotal role in mediating the protective effects on EPCs.

α4ß7 Integrin (LPAM-1) is upregulated at atherosclerotic lesions and is involved in atherosclerosis progression.

BACKGROUND/AIMS: Integrin activation and lymphocyte migration to the vascular intima is a key event in early atherosclerosis. α4ß7 integrin (LPAM-1) and its ligand, mucosal addressin cell adhesion molecule (MAdCAM-1) are known to play an important role in homing of activated lymphocytes to gut-associated lymphoid tissues. However, it is unclear whether α4ß7 integrin is involved in the pathogenesis of atherosclerosis. METHODS: The expressions of α4ß7 integrin and its ligands in atherosclerosis plaques from 12 week high fat diet (HFD) fed ApoE(-/-) and C57BL/6 mice were examined using immunofluorescent and immunohistochemical assays, respectively. We also generated ApoE/ß7 double deficient mice and compared atherosclerotic lesion development in ß7(+/+)ApoE(-/-) and ß7(-/-)ApoE(-/-) mice that were fed with HFD for 12 weeks. RESULTS: We found an upregulation of α4ß7 integrin and its ligands VCAM-1 and MAdCAM-1 at atherosclerosis plaques in Apolipoprotein E deficient (ApoE(-/-)) mice fed with HFD for 12 weeks. Over the 12 week HFD period, peripheral blood lymphocyte (PBL) expression of α4ß7 integrin increased in parallel with aortic lesion size. A removal of α4ß7 integrin by genetic deletion of the ß7 chain in the ApoE(-/-) mouse resulted in a markedly decreased 12 week-HFD atherosclerotic plaque area. ß7(-/-) ApoE(-/-) macrophages showed reduced acetylated and native LDL uptake and phagocytic activity, revealing possible roles for α4ß7 at two distinct stages of macrophage dysfunction during atherogenesis. Finally, a reduced activity of integrin downstream signalling components focal adhesion kinase (FAK) and MAPK/ERK1/2 in macrophage indicates their possible engagement during α4ß7 integrin signalling in atherosclerosis. CONCLUSIONS: Together our results reveal a critical role of α4ß7 in diet-induced atherosclerosis in mouse.

Application of adipose-derived stem cells in critical limb ischemia.

Peripheral artery disease is growing in global prevalence. Its most severe form, critical limb ischemia (CLI), is associated with high rates of limb loss, morbidity, and mortality. Neovascularization is the cornerstone of limb preservation in CLI. In the field of regenerative medicine, basic research and preclinical studies have been conducted using mesenchymal stem cells (MSCs) from adult tissues, including bone marrow and adipose tissue, to overcome clinical shortcomings. Adipose-derived stem cells (ASCs) display stable growth and proliferation kinetics and can differentiate into osteogenic, chondrogenic, adipogenic, myogenic or neurogenic lineages. ASCs are readily available from autologous adipose tissue, and have significant potential for tissue repair under conditions of myocardial infarction, heart failure, hind limb ischemia, and inflammation. This review highlights some of the key reports underlining the potential of ASCs, particularly in diseases involving neovascularization.

The meaning of work among Chinese university students: findings from prototype research methodology.

This study examined Chinese university students' conceptualization of the meaning of work. One hundred and ninety students (93 male, 97 female) from Beijing, China, participated in the study. Prototype research methodology (J. Li, 2001) was used to explore the meaning of work and the associations among the identified meanings. Cluster analysis was used to organize the identified meanings into a structure consisting of lateral and hierarchical levels. The themes that emerged fell into 2 large categories named "ideal" and "reality." A series of superordinate-level and basic-level prototypes were found under each of these 2 categories. These prototypes reflected influences from both Chinese traditional and Western value orientations, as well as perceptions that are to be understood in the contemporary social and economic contexts of China. Implications for career development theory, research, and practice are discussed.

Organocatalytic sequential hetero-Diels-Alder and Friedel-Crafts reaction: constructions of fused heterocycles with scaffold diversity.

A highly enantioselective aza-Diels-Alder and Friedel-Crafts reaction sequence of N-sulfonyl-1-aza-1,3-butadienes and aliphatic aldehydes tethered to an arene motif has been developed, affording the fused chiral piperidine frameworks with a versatile scaffold diversity. A similar strategy has been applied for the construction of complex chiral tetrahydroquinoxaline structures.

Aminocatalytic asymmetric inverse-electron-demand aza-Diels-Alder reaction of N-Ts-1-aza-1,3-butadienes based on coumarin cores.

The asymmetric inverse-electron-demand aza-Diels-Alder reaction of N-Ts-1-aza-1,3-butadienes derived from 3-argiocarbonylcoumarins and acetaldehyde has been developed using chiral secondary aminocatalysis, giving tricyclic chroman-2-one derivatives in high enantioselectivities (up to 95% ee).

An RNAi strategy for treatment of amyotrophic lateral sclerosis caused by mutant Cu,Zn superoxide dismutase.

Amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) is a neurodegenerative disease characterized by motor neuron degeneration, paralysis and death. One cause of this disease is mutations in the Cu,Zn superoxide dismutase (SOD1) gene. As mutant SOD1 acquires a toxic property that kills motor neurons, by reducing the mutant protein the disease progression may be slowed or prevented. While mutant SOD1 is toxic, the wild-type SOD1 is indispensable for motor neuron health. Therefore, the ideal therapeutic strategy would be to inhibit selectively the mutant protein expression. Previously we have demonstrated that RNA interference (RNAi) can selectively inhibit some mutant SOD1 expression. However, more than 100 SOD1 mutants can cause ALS and all mutants cannot be inhibited selectively by RNAi. To overcome this obstacle, we have designed a replacement RNAi strategy. Using this strategy, all mutants and wild-type genes are inhibited by RNAi. The wild-type SOD1 function is then replaced by designed wild-type SOD1 genes that are resistant to the RNAi. Here we demonstrate the concept of this strategy.

Multimerization and interaction of Toll and Spätzle in Drosophila.

The Toll family of receptors is required for innate immune response to pathogen-associated molecules, but the mechanism of signaling is not entirely clear. In Drosophila the prototypic Toll regulates both embryonic development and adult immune response. We demonstrate here that the host protein Spätzle can function as a ligand for Toll because Spätzle forms a complex with Toll in transgenic fly extracts and stimulates the expression of a Toll-dependent immunity gene, drosomycin, in adult flies. We also show that constitutively active mutants of Toll form multimers that contain intermolecular disulfide linkages. These disulfide linkages are critical for the activity of one of these mutant receptors, indicating that multimerization is essential for the constitutive activity. Furthermore, systematic mutational analysis revealed that a conserved cysteine-containing motif, different from the cysteines used for the intermolecular disulfide linkages, serves as a self-inhibitory module of Toll. Deleting or mutating this cysteine-containing motif leads to constitutive activity. This motif is located just outside the transmembrane domain and may provide a structural hindrance for multimerization and activation of Toll. Together, our results suggest that multimerization may be a regulated, essential step for Toll-receptor activation.