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Vanadium redox flow battery (VRFB) is a type of energy storage device known for its large-scale capacity, long-term durability, and high-level safety. It serves as an effective solution to address the instability and intermittency of renewable energy sources. Carbon-based materials are widely used as VRFB electrodes due to cost-effectiveness and well-stability. However, pristine electrodes need proper modification to overcome original poor hydrophilicity and fewer reaction active sites. Adjusting the carbon structure is recognized as a viable method to boost the electrochemical activity of electrodes. This review delves into the advancements in research related to ordered and disordered carbon structure electrodes including the adjusting methods, structural characteristics, and catalytic properties. Ordered carbon structures are categorized into nanoscale and macroscale orderliness based on size, leading to improved conductivity and overall performance of the electrode. Disordered carbon structures encompass methods such as doping atoms, grafting functional groups, and creating engineered holes to enhance active sites and hydrophilicity. Based on the current research findings on carbon electrode structures, this work puts forth some promising prospects for future feasibility.
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Photosystem II (PSII) uses solar energy to oxidize water and delivers electrons for life on Earth. The photochemical reaction center of PSII is known to possess two stationary states. In the open state (PSIIO), the absorption of a single photon triggers electron-transfer steps, which convert PSII into the charge-separated closed state (PSIIC). Here, by using steady-state and time-resolved spectroscopic techniques on Spinacia oleracea and Thermosynechococcus vulcanus preparations, we show that additional illumination gradually transforms PSIIC into a light-adapted charge-separated state (PSIIL). The PSIIC-to-PSIIL transition, observed at all temperatures between 80 and 308 K, is responsible for a large part of the variable chlorophyll-a fluorescence (Fv) and is associated with subtle, dark-reversible reorganizations in the core complexes, protein conformational changes at noncryogenic temperatures, and marked variations in the rates of photochemical and photophysical reactions. The build-up of PSIIL requires a series of light-induced events generating rapidly recombining primary radical pairs, spaced by sufficient waiting times between these events-pointing to the roles of local electric-field transients and dielectric relaxation processes. We show that the maximum fluorescence level, Fm, is associated with PSIIL rather than with PSIIC, and thus the Fv/Fm parameter cannot be equated with the quantum efficiency of PSII photochemistry. Our findings resolve the controversies and explain the peculiar features of chlorophyll-a fluorescence kinetics, a tool to monitor the functional activity and the structural-functional plasticity of PSII in different wild-types and mutant organisms and under stress conditions.
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Complexo de Proteína do Fotossistema II/química , Complexo de Proteína do Fotossistema II/metabolismo , Spinacia oleracea/química , Clorofila/análogos & derivados , Clorofila/química , Diurona/farmacologia , Fluorescência , Luz , Complexo de Proteína do Fotossistema II/efeitos dos fármacos , Conformação Proteica , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Thermosynechococcus/químicaRESUMO
Photosystem II (PSII) is a multisubunit pigment-protein complex and catalyzes light-driven water oxidation, leading to the conversion of light energy into chemical energy and the release of molecular oxygen. Psb27 is a small thylakoid lumen-localized protein known to serve as an assembly factor for the biogenesis and repair of the PSII complex. The exact location and binding fashion of Psb27 in the intermediate PSII remain elusive. Here, we report the structure of a dimeric Psb27-PSII complex purified from a psbV deletion mutant (ΔPsbV) of the cyanobacterium Thermosynechococcus vulcanus, solved by cryo-electron microscopy. Our structure showed that Psb27 is associated with CP43 at the luminal side, with specific interactions formed between Helix 2 and Helix 3 of Psb27 and a loop region between Helix 3 and Helix 4 of CP43 (loop C) as well as the large, lumen-exposed and hydrophilic E-loop of CP43. The binding of Psb27 imposes some conflicts with the N-terminal region of PsbO and also induces some conformational changes in CP43, CP47, and D2. This makes PsbO unable to bind in the Psb27-PSII. Conformational changes also occurred in D1, PsbE, PsbF, and PsbZ; this, together with the conformational changes occurred in CP43, CP47, and D2, may prevent the binding of PsbU and induce dissociation of PsbJ. This structural information provides important insights into the regulation mechanism of Psb27 in the biogenesis and repair of PSII.
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Proteínas de Bactérias/química , Complexo de Proteína do Fotossistema II/química , Multimerização Proteica , Proteínas de Bactérias/isolamento & purificação , Modelos Moleculares , Complexo de Proteína do Fotossistema II/isolamento & purificação , Complexo de Proteína do Fotossistema II/metabolismo , Ligação Proteica , Homologia Estrutural de Proteína , Thermosynechococcus/metabolismoRESUMO
In this paper, high-throughput sequencing technology was adopted to visualize the microbial communities on the surfaces of two types of carbon steel immersed in Sea Area â . The results showed that different microbial communities were formed on different carbon steel surfaces, in which the genus with the highest abundance on the surface of Q235 was Escherichia-Shigella, while anaerobic Desulfovibrio on the surface of 921a was the most abundant, and the dominant genus varied with the depth of the rust layer. In addition, the distribution of sulfate-reducing bacteria (SRB) on the surface of Q235 submerged in Sea Area â ¡ was compared with the sulfate-reducing bacteria's distribution in Sea Area â , using the environmental factors correlation analysis. The results showed that the concentrations of Ca2+, Na+, K+, Mg2+, and Al3+ were positively correlated with the distribution of SRB, while the concentrations of Cu2+, Zn2+, SO4 2-, Cl-, NO3 -, and organic carbon were negatively correlated with it. Furthermore, there was a highly significant correlation between each geochemical factor and Desulfotomaculum (p < 0.01).
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Cáusticos , Microbiota , Aço , Água do Mar/microbiologia , Sulfatos , CarbonoRESUMO
This study elucidated the chemical composition of essential oil from Centipeda minima (EOCM) and its antibacterial and antioxidant activities with two chemical monomers thymol and carvacrol. The main chemical composition of EOCM, analyzed by GC-MS, were trans-chrysanthenyl acetate, thymol, aromadendrene and ß-caryophyllene. In the screening of antibacterial activity against S. aureus, two monomers with antibacterial activity were obtained: thymol and carvacrol. The MIC of EOCM, thymol and carvacrol were 0.625 mg/mL, 0.156 mg/mL and 0.156 mg/mL, respectively. The experimental results were shown that three drugs could inhibit the growth of S. aureus and inhibit the formation of biofilm by changing the permeability of cell membrane and interfering with the metabolic activities in bacteria. The scavenging effects of the three drugs on DPPH radical and hydroxyl radical showed that the antioxidant effect of the three drugs was EOCM > carvacrol > thymol.
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Asteraceae , Óleos Voláteis , Óleos Voláteis/farmacologia , Óleos Voláteis/química , Timol/farmacologia , Antioxidantes/farmacologia , Staphylococcus aureus , Antibacterianos/farmacologia , Testes de Sensibilidade MicrobianaRESUMO
This study aimed to explore the effect of Ganmai Dazao Decoction on the ethology of rats with posttraumatic stress disorder(PTSD) and study the related mechanism through the changes in magnetic resonance imaging and protein expression. Sixty rats were randomly divided into 6 groups, namely the normal group, the model group, the low(1 g·kg~(-1)), medium(2 g·kg~(-1)), and high-dose Ganmai Dazao Decoction groups(4 g·kg~(-1)), and the positive control group(intragastric administration with 10.8 mg·kg~(-1) of fluoxetine), with 10 rats in each group. Two weeks after inducing PTSD by single-prolonged stress(SPS) in rats, the positive control group was given fluoxetine hydrochloride capsule by gavage, the low, medium, and high-dose groups were given Ganmai Dazao Decoction by gavage, and both the normal group and the model group were given the same volume of normal saline by gavage, each for 7 days. The open field experiment, elevated cross elevated maze, forced swimming experiment, and new object recognition test were carried out for the behavioral test. Three rats in each group were selected to detect the expression of neuropeptide receptor Y1(NPY1R) protein in the hippocampus by Western blot. Then, the other three rats in each group were selected to use the 9.4T magnetic resonance imaging experiment to observe the overall structural changes in the brain region and the anisotropy fraction of the hippocampus. The results of the open field experiment showed that the total distance and central distance of rats in the model group were significantly lower than those in the normal group, and the total distance and central distance of rats in the middle and high-dose Ganmai Dazao Decoction groups were higher than those in the model group. The results of the elevated cross maze test showed that medium and high-dose Ganmai Dazao Decoction remarkably increased the number of open arm entries and the residence time of open arm of rats with PTSD. The results of the forced swimming experiment showed that the immobility time in the water of the model group rats was significantly higher than that of the normal group, and Ganmai Dazao Decoction hugely reduced the immobility time in the water of rats with PTSD. The results of the new object recognition test showed that Ganmai Dazao Decoction significantly increased the exploration time of new objects and familiar objects in rats with PTSD. The results of Western blot showed that Ganmai Dazao Decoction significantly reduced the expression of NYP1R protein in the hippocampus of rats with PTSD. The 9.4T magnetic resonance examination found that there was no significant difference in the structural image among the groups. In the functional image, the fractional anisotropy(FA value) of the hippocampus in the model group was significantly lower than that in the normal group. The FA value of the hippocampus in the middle and high-dose Ganmai Dazao Decoction groups was higher than that in the model group. Ganmai Dazao Decoction reduces the injury of hippocampal neurons by inhibiting the expression of NYP1R in the hippocampus of rats with PTSD, thereby improving the nerve function injury of rats with PTSD and playing a neuroprotective role.
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Etologia , Transtornos de Estresse Pós-Traumáticos , Animais , Ratos , Fluoxetina , Hipocampo , Aprendizagem em LabirintoRESUMO
Photosystem II (PSII) has a number of hydrogen-bonding networks connecting the manganese cluster with the lumenal bulk solution. The structure of PSII from Thermosynechococcus vulcanus (T. vulcanus) showed that D1-R323, D1-N322, D1-D319 and D1-H304 are involved in one of these hydrogen-bonding networks located in the interfaces between the D1, CP43 and PsbV subunits. In order to investigate the functions of these residues in PSII, we generated seven site-directed mutants D1-R323A, D1-R323E, D1-N322R, D1-D319L, D1-D319R, D1-D319Y and D1-H304D of T. vulcanus and examined the effects of these mutations on the growth and functions of the oxygen-evolving complex. The photoautotrophic growth rates of these mutants were similar to that of the wild type, whereas the oxygen-evolving activities of the mutant cells were decreased differently to 63-91% of that of the wild type at pH 6.5. The mutant cells showed a higher relative activity at higher pH region than the wild type cells, suggesting that higher pH facilitated proton egress in the mutants. In addition, oxygen evolution of thylakoid membranes isolated from these mutants showed an apparent decrease compared to that of the cells. This is due to the loss of PsbU during purification of the thylakoid membranes. Moreover, PsbV was also lost in the PSII core complexes purified from the mutants. Taken together, D1-R323, D1-N322, D1-D319 and D1-H304 are vital for the optimal function of oxygen evolution and functional binding of extrinsic proteins to PSII core, and may be involved in the proton egress pathway mediated by YZ.
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Cianobactérias , Complexo de Proteína do Fotossistema II , Mutação , Oxigênio , Prótons , ThermosynechococcusRESUMO
Correction for 'The synergic effect between Mo species and acid sites in Mo/HMCM-22 catalysts for methane aromatization' by Ding Ma et al., Phys. Chem. Chem. Phys., 2005, 7, 3102-3109, https://doi.org/10.1039/B502794B.
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Photosystem I (PSI) is a large protein supercomplex that catalyzes the light-dependent oxidation of plastocyanin (or cytochrome c6 ) and the reduction of ferredoxin. This catalytic reaction is realized by a transmembrane electron transfer chain consisting of primary electron donor (a special chlorophyll (Chl) pair) and electron acceptors A0 , A1 , and three Fe4 S4 clusters, FX , FA , and FB . Here we report the PSI structure from a Chl d-dominated cyanobacterium Acaryochloris marina at 3.3 Å resolution obtained by single-particle cryo-electron microscopy. The A. marina PSI exists as a trimer with three identical monomers. Surprisingly, the structure reveals a unique composition of electron transfer chain in which the primary electron acceptor A0 is composed of two pheophytin a rather than Chl a found in any other well-known PSI structures. A novel subunit Psa27 is observed in the A. marina PSI structure. In addition, 77 Chls, 13 α-carotenes, two phylloquinones, three Fe-S clusters, two phosphatidyl glycerols, and one monogalactosyl-diglyceride were identified in each PSI monomer. Our results provide a structural basis for deciphering the mechanism of photosynthesis in a PSI complex with Chl d as the dominating pigments and absorbing far-red light.
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Clorofila/metabolismo , Cianobactérias/química , Feofitinas/metabolismo , Complexo de Proteína do Fotossistema I/química , Microscopia Crioeletrônica , Cianobactérias/metabolismo , Cianobactérias/ultraestrutura , Transporte de Elétrons , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema I/ultraestrutura , Estrutura Quaternária de ProteínaRESUMO
PsbO-D158 is a highly conserved residue of the PsbO protein in photosystem II (PSII), and participates in one of the hydrogen-bonding networks connecting the manganese cluster with the lumenal surface. In order to examine the role of PsbO-D158, we mutated it to E, N or K in Thermosynechococcus vulcanus and characterized photosynthetic properties of the mutants obtained. The growth rates of these three mutants were similar to that of the wild type, whereas the oxygen-evolving activity of the three mutant cells decreased to 60-64% of the wild type. Fluorescence kinetics showed that the mutations did not affect the electron transfer from QA to QB, but slightly affected the donor side of PSII. Moreover, all of the three mutant cells were more sensitive to high light and became slower to recover from photoinhibition. In the isolated thylakoid membranes from the three mutants, the PsbU subunit was lost and the oxygen-evolving activity was reduced to a lower level compared to that in the respective cells. PSII complexes isolated from these mutants showed no oxygen-evolving activity, which was found to be due to large or complete loss of PsbO, PsbV and PsbU during the process of purification. Moreover, PSII cores purified from the three mutants contained Psb27, an assembly co-factor of PSII. These results suggest that PsbO-D158 is required for the proper binding of the three extrinsic proteins to PSII and plays an important role in maintaining the optimal oxygen-evolving activity, and its mutation caused incomplete assembly of the PSII complex.
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Fotossíntese , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Criança , Pré-Escolar , Transporte de Elétrons , Fluorescência , Humanos , Manganês/metabolismo , Mutação , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/genética , Thermosynechococcus/genética , Thermosynechococcus/metabolismoRESUMO
PsbV (cytochrome c550) is one of the three extrinsic proteins of photosystem II (PSII) and functions to maintain the stability and activity of the Mn4CaO5 cluster, the catalytic center for water oxidation. PsbV-Y137 is the C-terminal residue of PsbV and is located at the exit of a hydrogen-bond network mediated by the D1-Y161-H190 residue pair. In order to examine the function of PsbV-Y137, four mutants, PsbV-Y137A, PsbV-Y137F, PsbV-Y137G, and PsbV-Y137W, were generated with Thermosynechococcus vulcanus (T. vulcanus). These mutants showed growth rates similar to that of the wild-type strain (WT); however, their oxygen-evolving activities were different. At pH 6.5, the oxygen evolution rates of Y137F and Y137W were almost identical to that of WT, whereas the oxygen evolution rates of the Y137A, Y137G mutants were 64% and 61% of WT, respectively. However, the oxygen evolution in the latter two mutants decreased less at higher pHs, suggesting that higher pHs facilitated oxygen evolution probably by facilitating proton egress in these two mutants. Furthermore, thylakoid membranes isolated from the PsbV-Y137A, PsbV-Y137G mutants exhibited much lower levels of oxygen-evolving activity than that of WT, which was found to be caused by the release of PsbV. In addition, PSII complexes purified from the PsbV-Y137A and PsbV-Y137G mutants lost all of the three extrinsic proteins but instead bind Psb27, an assembly cofactor of PSII. These results demonstrate that the PsbV-Tyr137 residue is required for the stable binding of PsbV to PSII, and the hydrogen-bond network mediated by D1-Y161-H190 is likely to function in proton egress during water oxidation.
Assuntos
Complexo de Proteína do Fotossistema II/metabolismo , Ligação de Hidrogênio , Modelos Moleculares , Mutagênese Sítio-Dirigida , Oxirredução , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/genética , Prótons , Thermosynechococcus/genética , Thermosynechococcus/metabolismo , Água/metabolismoRESUMO
Recent chlorophyll-a fluorescence yield measurements, using single-turnover saturating flashes (STSFs), have revealed the involvement of a rate-limiting step in the reactions following the charge separation induced by the first flash. As also shown here, in diuron-inhibited PSII core complexes isolated from Thermosynechococcus vulcanus the fluorescence maximum could only be reached by a train of STSFs. In order to elucidate the origin of the fluorescence yield increments in STSF series, we performed transient absorption measurements at 819 nm, reflecting the photooxidation and re-reduction kinetics of the primary electron donor P680. Upon single flash excitation of the dark-adapted sample, the decay kinetics could be described with lifetimes of 17 ns (â¼50%) and 167 ns (â¼30%), and a longer-lived component (â¼20%). This kinetics are attributed to re-reduction of P680â¢+ by the donor side of PSII. In contrast, upon second-flash (with Δt between 5 µs and 100 ms) or repetitive excitation, the 819 nm absorption changes decayed with lifetimes of about 2 ns (â¼60%) and 10 ns (â¼30%), attributed to recombination of the primary radical pair P680â¢+ Pheoâ¢- , and a small longer-lived component (â¼10%). These data confirm that only the first STSF is capable of generating stable charge separation - leading to the reduction of QA ; and thus, the fluorescence yield increments elicited by the consecutive flashes must have a different physical origin. Our double-flash experiments indicate that the rate-limiting steps, detected by chlorophyll-a fluorescence, are not correlated with the turnover of P680.
Assuntos
Clorofila A/metabolismo , Cianobactérias/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , OxirreduçãoRESUMO
Autophagy plays an important role in alleviating oxidative stress and stabilizing atherosclerotic plaques. However, the potential role of autophagy in endothelial vasodilation function has rarely been studied. This study aimed to investigate whether rhynchophylla total alkaloid (RTA) has a positive role in enhancing autophagy through decreasing oxidative stress, and improving endothelial vasodilation. In oxidized low-density lipoprotein (ox-LDL)-treated human umbilical vein endothelial cells (HUVECs), RTA (200 mg/L) significantly suppressed ox-LDL-induced oxidative stress through rescuing autophagy, and decreased cell apoptosis. In spontaneous hypertensive rats (SHR), administration of RTA (50 mg·kg-1·d-1, ip, for 6 weeks) improved endothelin-dependent vasodilation of thoracic aorta rings. Furthermore, RTA administration significantly increased the antioxidant capacity and alleviated oxidative stress through enhancing autophagy in SHR. In ox-LDL-treated HUVECs, we found that the promotion of autophagy by RTA resulted in activation of the AMP-activated protein kinase (AMPK) signaling pathway. Our results show that RTA treatment rescues the ox-LDL-induced autophagy impairment in HUVECs and improves endothelium-dependent vasodilation function in SHR.
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Alcaloides/farmacologia , Autofagia/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Uncaria/química , Vasodilatação/efeitos dos fármacos , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Aorta/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos , Lipoproteínas LDL/metabolismo , Masculino , Ratos , Transdução de Sinais/efeitos dos fármacosRESUMO
Various carbonaceous species were controllably deposited on Co/Al2O3 catalysts using ethylene as carbon source during the activation process for Fischer-Tropsch synthesis (FTS). Atomic, polymeric and graphitic carbon were distinguished by Raman spectroscopy, thermoanalysis and temperature programmed hydrogenation. Significant changes occurred in both the catalytic activity and selectivity toward hydrocarbon products after ethylene treatment. The activity decreased along with an increase in CH4 selectivity, at the expense of a remarkable decrease of heavy hydrocarbon production, resulting in enhanced selectivity for the gasoline fraction. In situ XPS experiments show the possible electron transfer from cobalt to carbon and the blockage of metallic cobalt sites, which is responsible for the deactivation of the catalyst. DFT calculations reveal that the activation barrier (Ea) of methane formation decreases by 0.61 eV on the carbon-absorbed Co(111) surface, whereas the Ea of the CH + CH coupling reaction changes unnoticeably. Hydrogenation of CHx to methane becomes the preferable route among the elementary reactions on the Co(111) surface, leading to dramatic changes in the product distribution. Detailed coke-induced deactivation mechanisms of Co-based catalysts during FTS are discussed.
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Tissue and organ fibrosis is the major cause for disability and death related to a variety of diseases worldwide. As specific therapies to halt, or even to reverse the existing tissue fibrosis are not yet available, it is of great significance to find new anti-fibrosis therapeutic agents. Tissue and organ fibrosis is a nonphysiological scarring process, associated with excessive deposition of extracellular matrix, and leads to impairment of organ function. Fibrotic lesions of all organs show similar histological abnormalities. In recent years, plenty of studies showed that Baicalin and baicalein had anti-fibrosis effects in different tissues or organs. In this paper, the effects and mechanisms of baicalin and baicalein on different organ fibrosis were reviewed. Baicalin and its aglycone baicalein had similarity in structural and pharmacological characteristics, with broad biotransformation effect within the body. The research suggested that baicalin and baicalein can suppress different tissue and organ fibrosis occurrence and development via various mechanisms, including down-regulating expression of promote-fibrosis cytokines, inhibiting pro-fibrogenic signaling pathways, anti-inflammatory and anti-oxidant effects. Though baicalin and baicalein are promising anti-fibrosis agents, there is still a long way to go before being approved as specific anti-fibrotic drugs.
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Fibrose/tratamento farmacológico , Flavanonas/farmacologia , Flavonoides/farmacologia , HumanosRESUMO
To study the inhibitory effect of Glehniae Radix petroleum ether part on TGF-ß1-induced epithelial mesenchymal transition in non-small cell lung cancer A549 and its possible mechanism. With type â ¡ epithelial cells of lung cancer A549 as the research object, the experiment was performed in 5 µgâ¢L⻹ TGF-ß1-induced epithelial mesenchymal transition model,and blank control group, model group and Glehniae Radix petroleum ether group were set up. MTT assay was carried out to detect the effect of petroleum ether extract of Glehniae Radix on the survival of A549 cells. A549 cells induced by TGF-ß1(5 µgâ¢L⻹) was intervened by different polar parts of Glehniae Radix, Real-time quantitative polymerase chain reaction(RT-qPCR) was used to analyze mRNA expressions of the epithelial mesenchymal transition markers, such as Colâ ,E-cadherin,Vimentin and α-SMA. Enzyme linked immunosorbent assay(ELISA) was used to detect hydroxyproline(HYP) level. The migration and invasion abilities of cells were detected through wound scratch assay. According to the experimental results, the petroleum ether extract of Glehniae Radix could inhibit the growth of A549 cells in a concentration-dependent manner. Compared with model group, Glehniae Radix petroleum ether part group could effectively inhibit mRNA expressions of Colâ ,Vimentin and α-SMA, but improve expression of E-cadherin.Glehniae Radix petroleum ether part could reduce the content of hydroxyproline in cells and inhibit the migration of A549 cells.Therefore, the petroleum ether extract of Glehniae Radix can effectively inhibit the occurrence of epithelial mesenchymal transition induced by TGF-ß1 induced alveolar epithelial cells, and Glehniae Radix petroleum ether part may be a potential drug for idiopathic pulmonary fibrosis. The mechanism may be achieved through the regulation of Colâ , Vimentin, α-SMA and E-cadherin.
Assuntos
Apiaceae/química , Células Epiteliais/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Extratos Vegetais/farmacologia , Células A549 , Actinas/metabolismo , Alcanos , Antígenos CD , Caderinas/metabolismo , Carcinoma Pulmonar de Células não Pequenas , Colágeno/metabolismo , Células Epiteliais/citologia , Humanos , Neoplasias Pulmonares , Raízes de Plantas/química , Fator de Crescimento Transformador beta1/farmacologia , Vimentina/metabolismoRESUMO
Integrating natural and artificial photosynthetic platforms is an important approach to developing solar-driven hybrid systems with exceptional function over the individual components. A natural-artificial photosynthetic hybrid platform is formed by wiring photosystem II (PSII) and a platinum-decorated silicon photoelectrochemical (PEC) cell in a tandem manner based on a photocatalytic-PEC Z-scheme design. Although the individual components cannot achieve overall water splitting, the hybrid platform demonstrated the capability of unassisted solar-driven overall water splitting. Moreover, H2 and O2 evolution can be separated in this system, which is ascribed to the functionality afforded by the unconventional Z-scheme design. Furthermore, the tandem configuration and the spatial separation between PSII and artificial components provide more opportunities to develop efficient natural-artificial hybrid photosynthesis systems.
Assuntos
Técnicas Eletroquímicas , Complexo de Proteína do Fotossistema II/isolamento & purificação , Silício/isolamento & purificação , Água/metabolismo , Hidrogênio/química , Hidrogênio/isolamento & purificação , Hidrogênio/metabolismo , Oxigênio/química , Oxigênio/isolamento & purificação , Oxigênio/metabolismo , Processos Fotoquímicos , Complexo de Proteína do Fotossistema II/metabolismo , Platina/química , Platina/metabolismo , Silício/química , Silício/metabolismo , Água/químicaRESUMO
The liver plays a central role in regulating cholesterol homeostasis. High fat diets have been shown to induce obesity and hyperlipidemia. Despite considerable advances in our understanding of cholesterol metabolism, the regulation of liver cholesterol biosynthesis in response to high fat diet feeding has not been fully addressed. The aim of the present study was to investigate mechanisms by which a high fat diet caused activation of liver 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) leading to increased cholesterol biosynthesis. Mice were fed a high fat diet (60% kcal fat) for 5weeks. High fat diet feeding induced weight gain and elevated lipid levels (total cholesterol and triglyceride) in both the liver and serum. Despite cholesterol accumulation in the liver, there was a significant increase in hepatic HMG-CoA reductase mRNA and protein expression as well as enzyme activity. The DNA binding activity of sterol regulatory element binding protein (SREBP)-2 and specific protein 1 (Sp1) were also increased in the liver of mice fed a high fat diet. To validate the in vivo findings, HepG2 cells were treated with palmitic acid. Such a treatment activated SREBP-2 as well as increased the mRNA and enzyme activity of HMG-CoA reductase leading to intracellular cholesterol accumulation. Inhibition of Sp1 by siRNA transfection abolished palmitic acid-induced SREBP-2 and HMG-CoA reductase mRNA expression. These results suggest that Sp1-mediated SREBP-2 activation contributes to high fat diet induced HMG-CoA reductase activation and increased cholesterol biosynthesis. This may play a role in liver cholesterol accumulation and hypercholesterolemia.
Assuntos
Gorduras na Dieta/administração & dosagem , Hidroximetilglutaril-CoA Redutases/metabolismo , Animais , Sequência de Bases , Linhagem Celular , Primers do DNA , Ativação Enzimática , Regulação Enzimológica da Expressão Gênica/fisiologia , Humanos , Hidroximetilglutaril-CoA Redutases/genética , Metabolismo dos Lipídeos , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase em Tempo Real , Fator de Transcrição Sp1/fisiologia , Proteína de Ligação a Elemento Regulador de Esterol 2/fisiologiaRESUMO
BACKGROUND: The clinical efficacy and safety of low-dose levothyroxine in the treatment of idiopathic nephritic syndrome accompanied by thyroid dysfunction have not been established. METHODS: One hundred and sixty-four patients were divided into three groups according to the levels of thyroid hormone and treatment. The thyroid status, efficacy and adverse reactions of thyroid treatment were observed in each group. RESULTS: Thyroid dysfunction was found in 73 patients. 40 cases were treated with steroids combined with levothyroxine. Proteinuria, cholesterol and thyroid-stimulating hormone (TSH) levels were significantly higher in patients with thyroid dysfunction, whereas serum albumin and free and total T3 and T4 levels were lower than those of euthyroid patients. The time for proteinuria remission in patients receiving levothyroxine therapy was shorter and their serum albumin higher than for patients without levothyroxine treatment. CONCLUSIONS: Thyroid hormonal changes are related to the degree of both proteinuria and serum albumin in patients with INS. Combined treatment with low-dose levothyroxine supplementation and steroids in children with INS and thyroid dysfunction is associated with reduced proteinuria and increased plasma albumin compared with patients treated with steroids only.
Assuntos
Corticosteroides/administração & dosagem , Síndrome Nefrótica/tratamento farmacológico , Tiroxina/administração & dosagem , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Síndrome Nefrótica/complicações , Estudos Retrospectivos , Doenças da Glândula Tireoide/complicaçõesRESUMO
Chinese soft-shelled turtle (Pelodiscus sinensis) hibernates without eating and drinking when the ambient temperature is very low. To better understand the characteristics of energy utilization during hibernation, the turtles in the physiological phases of summer active (SA), Pre-Hibernation (Pre-H), Mid-Hibernation (Mid-H) and early arousal (EA) were sampled. The results showed that the levels of serum triglyceride and hepatic lipid droplet were markedly increased in Pre-H and decreased in Mid-H compared with that in SA, indicating that P. sinensis experiences lipid accumulation in Pre-H and lipid is the predominant energy reserve during hibernation. The mRNA expression levels of genes (FABP and CPT-2) involved in lipolysis and lipid oxidation were up-regulated in Mid-H, while the genes related to lipid synthesis (FAS, ACSL-1, ACC, elovl5, and SCD1) were inhibited in Mid-H. Meanwhile, the mRNA expression levels of endoplasmic reticulum stress marker gene Bip and key genes (ATF4, ATF6, and IRE1α) involving the unfolded protein response were significantly increased in Mid-H and EA. Also, the expression levels of genes (ASK1, JNK1, and Bax) associated with cell apoptosis increased in Mid-H and EA, however, the expression of Bcl2 was inhibited in Mid-H. Therefore, hibernation can cause endoplasmic reticulum stress and apoptosis. The findings will provide a theoretical framework for an animal's cold adaptation and offer insights into preventing and managing metabolic syndrome.