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1.
Sci Rep ; 14(1): 4663, 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38409301

RESUMO

Wireless traffic prediction is vital for intelligent cellular network operations, such as load-aware resource management and predictive control. Traditional centralized training addresses this but poses issues like excessive data transmission, disregarding delays, and user privacy. Traditional federated learning methods can meet the requirement of jointly training models while protecting the privacy of all parties' data. However, challenges arise when the local data features among participating parties exhibit inconsistency, making the training process difficult to sustain. Our study introduces an innovative framework for wireless traffic prediction based on split learning (SL) and vertical federated learning. Multiple edge clients collaboratively train high-quality prediction models by utilizing diverse traffic data while maintaining the confidentiality of raw data locally. Each participant individually trains dimension-specific prediction models with their respective data, and the outcomes are aggregated through collaboration. A partially global model is formed and shared among clients to address statistical heterogeneity in distributed machine learning. Extensive experiments on real-world datasets demonstrate our method's superiority over current approaches, showcasing its potential for network traffic prediction and accurate forecasting.

2.
Heliyon ; 9(11): e21137, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37920497

RESUMO

Extracts of the Pueraria mirifica (Kudzu) plant have several significant human health-promoting benefits. This study utilized orthogonal tests to evaluate the effects of differential ultrasonic power, microwave, and time on the rate of flavonoid extraction from Kudzu samples. Ultrafine processing resulted in finer powder microstructures (SEM) with high solubility. The smallest D50 measurements of ultrafine Kudzu flower and root particles were 11.7 ± 0.004b and 14.3 ± 0.013c µm, respectively. Increasing ultrasonic power from 200 to 600 W yielded increased flavonoids. Increased microwave power from 200 to 800 W also yielded increased flavonoid extract. We found that the best combination factor was A3B2C3 (A-ultrasonic power, B- time, and C- microwave power), showing that flavonoid extraction rate was primarily influenced by microwave power, followed by ultrasonic time and ultrasonic power. Conclusively, ultrafine pulverization increased the flavonoid extraction rate from Kudzu powder particles. Also, scanning electron microscopy results showed that the finer particles had increased solubility.

3.
Appl Biochem Biotechnol ; 195(1): 610-622, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36114923

RESUMO

Using first-principles calculations, we studied the electronic properties of graphdiyne (GDY) nanosheet and its Si-doped counterpart, SiGDY. Both GDY and SiGDY sheet surfaces were examined for acetaminophen (AP) drug adsorption using adsorption energy, charge transfer, and change in electrical conductivity (as indicators). As shown in this study, pure GDY has little affinity for AP. In specific, only 7.83 percent of the GDY surface's bandwidth energy changed after AP adsorption. On SiGDY, AP has a gaseous energy value of - 18.75 kcal/mol, as well as an aqueous energy value of - 49.39 kcal/mol. The water-phase solubility of the prescribed medications is determined using their solvation energy value. These charges are transferred between AP and the SiGDY sheet, which is extremely positively charged, giving AP the necessary binding energy. After AP adsorption, the electrical conductivity of SiGDY was increased by approximately 19.01 percent.


Assuntos
Acetaminofen , Transtornos Relacionados ao Uso de Substâncias , Humanos , Silício , Adsorção , Condutividade Elétrica
4.
Syst Biol Reprod Med ; 68(5-6): 370-383, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36016468

RESUMO

This study investigated the expression and clinical significance of long intergenic noncoding RNA 00665 (LINC00665) in ovarian cancer (OC), as well as its effect on the malignant biological behavior of OC cells. The expression of LINC00665, miR-148b-3p, and Krüppel-like factor 5 (KLF5) in OC tissues and cells were determined by RT-qPCR. Western blot was used to detect the protein expression of KLF5. The expression patterns of LINC00665 in nuclear and cytoplasm fractions were undertaken using RT-qPCR. In addition, CCK-8 assay, clone formation assay, transwell, scratch test, and flow cytometry were respectively used to detect the cell activity, proliferation, invasiveness, healing of cells, and apoptosis rate of OC cells. Furthermore, the interactions between LINC00665 and miR-148b-3p and between miR-148b-3p and KLF5 were verified by the luciferase reporter assay, and the correlations among these three genes were analyzed. LINC00665 expression was upregulated both in OC cell lines and tissues. Si-LINC00665 inhibited cell proliferation, invasion, and migration and induced apoptosis to a certain extent. The subcellular fraction assay revealed LINC00665 to be located mainly in the cytoplasm. miR-148b-3p was a target of LINC00665, and KLF5 was directly targeted by miR-148b-3p. Si-LINC00665 inhibited KLF5 expression, miR-148b-3p inhibitor promoted KLF5 expression, and si-KLF5 inhibited LINC00665 expression. Interestingly, the expression of LINC00665 was reversely associated with miR-148b-3p expression but positively correlated with KLF5. Furthermore, miR-148b-3p expression was negatively correlated with KLF5. In addition, si-KLF5 inhibited the malignant biological behavior of OC cells, whereas miR-148b-3p inhibitor had the opposite effect. Most importantly, the si-LINC00665 could reverse the promotion effect of the miR-148b-3p inhibitor on the malignant biological behavior of OC cells. LINC00665 can be used as an effective prognostic indicator of OC, which has the potential to be a new therapeutic target.


Assuntos
Fatores de Transcrição Kruppel-Like , MicroRNAs , Neoplasias Ovarianas , RNA Longo não Codificante , Feminino , Humanos , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , MicroRNAs/genética , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , RNA Longo não Codificante/genética
5.
Nanomaterials (Basel) ; 12(11)2022 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-35683757

RESUMO

Mercury, as one type of toxic heavy metal, represents a great threat to environmental and biological metabolic systems. Thus, reliable and sensitive quantitative detection of mercury levels is particularly meaningful for environmental protection and human health. We proposed a high-throughput single-particle color imaging strategy under dark-field microscopy (DFM) for mercury ions (Hg2+) detection by using individual concave cube Au nanoparticles as optical probes. In the presence of ascorbic acid (AA), Hg2+ was reduced to Hg which forms Au-Hg amalgamate with Au nanoparticles, altering their localized surface plasmon resonance (LSPR). Transmission electron microscopy (TEM) images demonstrated that the concave cube Au nanoparticles were approaching to sphere upon increasing the concentration of Hg2+. The nanoparticles underwent an obvious color change from red to yellow, green, and finally blue under DFM due to the shape-evolution and LSPR changes. In addition, we demonstrated for the first time that the LSPR of Au-Hg amalgamated below 400 nm. Inspired by the above-mentioned results, single-particle color variations were digitalized by converting the color image into RGB channels to obtain (green+blue)/red intensity ratios [(G+B)/R]. The concentration-dependence change was quantified by statistically analyzing the (G+B)/R ratios of a large number of particles. A linear range from 10 to 2000 nM (R2 = 0.972) and a limit of detection (LOD) of 1.857 nM were acquired. Furthermore, many other metal ions, like Cu2+, Cr3+, etc., did not interfere with Hg2+ detection. More importantly, Hg2+ content in industrial wastewater samples and in the inner regions of human HepG2 cells was determined, showing great potential for developing a single-particle color imaging sensor in complex biological samples using concave cube Au nanoparticles as optical probes.

6.
Comput Math Methods Med ; 2022: 6103649, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35371276

RESUMO

With the development of antibacterial, synergistic, and drug resistance research, the requirements for the specificity of antibiotics are getting higher and higher. In the research based on the specificity of antibiotics, this article uses intelligent medical image processing methods to study the specificity of the antibacterial efficiency of nanocopper oxide and the inhibition of drug resistance. Copper oxide nanorods have the properties of surface effect, quantum size effect, volume effect, and macroscopic quantum tunneling effect. Compared with ordinary copper oxide, the nanoscale gives them special properties of electricity, optics, and catalysis. In this article, in the research based on the specificity of antibiotics, the specificity of antimicrobial efficiency and drug resistance inhibition of nanocopper oxide are studied by using smart medical information processing methods. Drug sensitivity paper tablet method is a drug sensitivity experiment to determine drug sensitivity to make accurate and effective use of drugs for treatment. Colony growth method is used to take the equivalent volume of fermentation liquid at different times to determine the content of bacteria. In this article, Staphylococcus aureus is cultivated by the drug-sensitive disk method and the colony growth method. Then, according to this type of antibiotic and bacterial group combination, Staphylococcus aureus is divided into a penicillin group, nanocopper oxide group, and cephalosporin group. 0.5 g of the corresponding antibiotic was added to each group. TMP (trimethoprim) acts as a synergist, and the ratio of TMP to antibiotic is 1 : 5. Finally, we compared the inhibitory concentration indexes of the above three groups and inferred the synergistic effect of antibiotics and the inhibitory effect of drug resistance through the specificity of the antibiotics that the antibacterial activity was further studied. The results showed that the antibacterial effect of TMP combined with nano-CuO was 38% higher than that of the penicillin group and 41% higher than that of the cephalosporin group. In addition, the combined effect of TMP and antibiotics is greater than the combined effect of TMP and antibiotics alone. From the observation of smart medical system processing, it is speculated that the reason may be that they provide each other with a suitable environment. Because of this combined effect between the TMP and the antibiotic, it can influence each other. From the results, the combined effect is 48% higher than the combined effect. Therefore, according to the results of medical imaging, the combination of antibiotics and antibacterial synergists can improve specificity and antibacterial rate.


Assuntos
Antibacterianos , Bactérias , Antibacterianos/farmacologia , Diagnóstico por Imagem , Resistência a Medicamentos , Humanos , Testes de Sensibilidade Microbiana
7.
Front Mol Biosci ; 8: 699929, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34368228

RESUMO

SARS-CoV-2 infection has become an urgent public health concern worldwide, severely affecting our society and economy due to the long incubation time and high prevalence. People spare no effort on the rapid development of vaccine and treatment all over the world. Amongst the numerous ways of tackling this pandemic, some approaches using extracellular vesicles (EVs) are emerging. In this review, we summarize current prevalence and pathogenesis of COVID-19, involving the combination of SARS-CoV-2 and virus receptor ACE2, endothelial dysfunction and micro thrombosis, together with cytokine storm. We also discuss the ongoing EVs-based strategies for the treatment of COVID-19, including mesenchymal stem cell (MSC)-EVs, drug-EVs, vaccine-EVs, platelet-EVs, and others. This manuscript provides the foundation for the development of targeted drugs and vaccines for SARS-CoV-2 infections.

8.
Folia Neuropathol ; 57(2): 117-128, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31556572

RESUMO

Previous studies have shown that Huangqi glycoprotein (HQGP) has an anti-inflammatory effect in vitro, and suppressed experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis; however, the mechanism underlying its effect is largely unknown. In this manuscript we investigated the mechanisms by which HQGP protect mice from EAE. HQGP was extracted from Astragalus membranaceus and purified by anion-exchange and gel filtration chromatography. HQGP delayed disease onset, reduced disease severity and alleviated inflammation and demyelination in the central nervous system (CNS). Moreover, HQGP reduced the infiltration of pathogenic immune cells and increased the expression of microtubule-associated protein 2 (MAP-2) and neuronal nuclei (NeuN) in the CNS. HQGP treatment also reduced the expression of chemokines such as CCL2 and CCL5 and the production of tumor necrosis factor α (TNF-α), interleukin (IL)-1ß, IL-6, but increased the level of IL-10. These results demonstrate that HQGP suppressed EAE development by modulating the immune system and the infiltration of leukocytes to the CNS as well as promoting axon and neural repair.


Assuntos
Medicamentos de Ervas Chinesas/uso terapêutico , Encefalomielite Autoimune Experimental/tratamento farmacológico , Fármacos Neuroprotetores/uso terapêutico , Animais , Astragalus propinquus , Quimiocinas/metabolismo , Citocinas/metabolismo , Medicamentos de Ervas Chinesas/farmacologia , Encefalomielite Autoimune Experimental/metabolismo , Feminino , Camundongos , Fármacos Neuroprotetores/farmacologia , Índice de Gravidade de Doença
9.
Nat Commun ; 9(1): 4068, 2018 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-30287809

RESUMO

Van der Waals heterostructures stacked from different two-dimensional materials offer a unique platform for addressing many fundamental physics and construction of advanced devices. Twist angle between the two individual layers plays a crucial role in tuning the heterostructure properties. Here we report the experimental investigation of the twist angle-dependent conductivities in MoS2/graphene van der Waals heterojunctions. We found that the vertical conductivity of the heterojunction can be tuned by ∼5 times under different twist configurations, and the highest/lowest conductivity occurs at a twist angle of 0°/30°. Density functional theory simulations suggest that this conductivity change originates from the transmission coefficient difference in the heterojunctions with different twist angles. Our work provides a guidance in using the MoS2/graphene heterojunction for electronics, especially on reducing the contact resistance in MoS2 devices as well as other TMDCs devices contacted by graphene.

10.
Nanoscale ; 10(39): 18728-18733, 2018 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-30270363

RESUMO

Manipulating the magnetization of ferromagnets by the current-induced spin-orbit torque has great potential application in the design of low energy consumption spintronic devices. Normally, an external magnetic field is needed for the reversal of current assisted magnetization by the spin-orbit torque. Recently, the switching of magnetization driven by the spin-orbit torque in the absence of an external magnetic field was reported in a Ta/Co20Fe60B20/TaOx system with lateral structural asymmetry. To understand the physics behind this experiment, we performed first principles calculations on the potential profile at the interface between the ferromagnetic film and the wedge-shaped deposited metal oxide in the Ta/Co/TaO system. This revealed that the lateral structural asymmetry generates two additional Rashba interactions which can reduce the minimum external field required to reverse the magnetization. In addition, we derived the Landau-Lifshitz-Gilbert equation from a quantum transport perspective and numerically investigated the magnetization dynamics in ferromagnetic films induced by Rashba interactions including those generated by lateral asymmetry. Our theoretical simulation provides microscopic explanations of experimental observations of magnetization switching in the absence of an external field of devices with lateral structural asymmetry.

11.
J Phys Condens Matter ; 30(43): 435303, 2018 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-30226213

RESUMO

An intriguing observation on the quantum anomalous Hall effect (QAHE) in magnetic topological insulators (MTIs) is the dissipative edge states, where quantized Hall resistance is accompanied by nonzero longitudinal resistance. We numerically investigate this dissipative behavior of QAHE in MTIs with a three-dimensional tight-binding model and non-equilibrium Green's function formalism. It is found that, in clean samples, the geometric mismatch between the detecting electrodes and the MTI sample leads to additional scattering in the central Hall bar, which is similar to the effect of splitting gates in the traditional Hall effect. As a result, while the Hall resistance remains quantized, the longitudinal resistance deviates from zero due to such additional scattering. It is also shown that external magnetic fields as well as disorder scattering can suppress the dissipation of the longitudinal resistance. These results are in good agreement with previous experimental observations and provide insight on the fabrication of QAHE devices.

12.
Folia Neuropathol ; 55(4): 308-316, 2017.
Artigo em Polonês | MEDLINE | ID: mdl-29363905

RESUMO

Huangqi glycoprotein (HQGP) is prepared from Astragalus membranaceus by ammonium sulfate precipitation. It was indicated that HQGP has an immunoregulatory effect. In this study, we established a chronic experimental autoimmune encephalomyelitis (EAE) model and observed the therapeutic effect and possible mechanisms of HQGP (intraperitoneally at 1 mg/kg/day) on EAE. The results showed that HQGP delayed onset and ameliorated severity of EAE, and reduced the infiltration and accumulation of pathogenic T cells in the central nerves system (CNS). HQGP also reduced the production of IL-6, IL-17 and TNF-α and increased the level of IL-10. However, the level of IFN-γ production was also increased in HQGP-treated mice compared with EAE control mice. In brain, chemokines such as CCL2 and CCL5 were inhibited in HQGP-treated EAE compared with control mice. These results demonstrate that HQGP alleviates the pathogenesis of EAE possibly by suppressing the neuroinflammation and decreasing the secretion of chemokines and cell adhesion..


Assuntos
Anti-Inflamatórios/farmacologia , Medicamentos de Ervas Chinesas/farmacologia , Encefalomielite Autoimune Experimental/patologia , Animais , Astragalus propinquus , Sistema Nervoso Central/efeitos dos fármacos , Sistema Nervoso Central/patologia , Feminino , Glicoproteínas/farmacologia , Camundongos Endogâmicos C57BL
13.
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi ; 32(1): 54-8, 2016 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-26728379

RESUMO

OBJECTIVE: To explore the therapeutic effect and possible mechanism of Huangqi glycoprotein (HQGP) on the development of experimental autoimmune encephalomyelitis (EAE). METHODS: Female C57BL/6 mice were immunized subcutaneously with myelin oligodendrocyte glycoprotein peptide-35-55 (MOG35-55) and divided into HQGP-treated group and EAE control group. Clinical score and body mass were recorded every other day. Inflammatory cell infiltrations of spinal cord were observed by HE and immunofluorescence staining. The cell viability of splenic mononuclear cells (MNCs) was detected by MTT assay. The release of NO was measured by Griess method. The levels of TNF-α, IL-6 and IFN-γ were determined by ELISA. The subtypes of CD4(+)T cells were analyzed by flow cytometry. RESULTS: HQGP treatment delayed the onset of EAE, attenuated the clinical symptoms and inhibited CD68(+) macrophage infiltration into the central nervous system. HQGP inhibited the viability of splenic MNCs, downregulated the secretion of NO, TNF-α, IL-6, and increased the secretion of IFN-γ. In addition, HQGP treatment effectively increased the numbers of CD4(+)CD25(+) T cells, CD4(+)IL-10(+) T cells and CD4(+)IFN-γ(+) T cells. CONCLUSION: HQGP relieve the inflammation of EAE via reducing the number of T cell subsets and inhibiting the secretion of inflammatory cytokines.


Assuntos
Medicamentos de Ervas Chinesas/farmacologia , Encefalomielite Autoimune Experimental/prevenção & controle , Glicoproteínas/farmacologia , Fatores Imunológicos/farmacologia , Animais , Antígenos CD/imunologia , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/imunologia , Antígenos de Diferenciação Mielomonocítica/metabolismo , Astragalus propinquus/química , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Citocinas/imunologia , Citocinas/metabolismo , Encefalomielite Autoimune Experimental/imunologia , Ensaio de Imunoadsorção Enzimática , Feminino , Citometria de Fluxo , Imunofluorescência , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Glicoproteína Mielina-Oligodendrócito/imunologia , Óxido Nítrico/imunologia , Óxido Nítrico/metabolismo , Medula Espinal/efeitos dos fármacos , Medula Espinal/imunologia , Medula Espinal/metabolismo , Baço/efeitos dos fármacos , Baço/imunologia , Baço/metabolismo , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo
14.
Plant Cell Physiol ; 55(8): 1426-36, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24850836

RESUMO

The secretion of organic acid anions from roots is an important mechanism for plant aluminum (Al) tolerance. Here we report cloning and characterizing BoMATE (KF031944), a multidrug and toxic compound extrusion (MATE) family gene from cabbage (Brassica oleracea). The expression of BoMATE was more abundant in roots than in shoots, and it was highly induced by Al treatment. The (14)C-citrate efflux experiments in oocytes demonstrated that BoMATE is a citrate transporter. Electrophysiological analysis and SIET analysis of Xenopus oocytes expressing BoMATE indicated BoMATE is activated by Al. Transient expression of BoMATE in onion epidermal cells demonstrated that it localized to the plasma membrane. Compared with the wild-type Arabidopsis, the transgenic lines constitutively overexpressing BoMATE enhanced Al tolerance and increased citrate secretion. In addition, Arabidopsis transgenic lines had a lower K(+) efflux and higher H(+) efflux, in the presence of Al, than control wild type in the distal elongation zone (DEZ). This is the first direct evidence that MATE protein is involved in the K(+) and H(+) flux in response to Al treatment. Taken together, our results show that BoMATE is an Al-induced citrate transporter and enhances aluminum tolerance in Arabidopsis thaliana.


Assuntos
Alumínio/farmacologia , Arabidopsis/fisiologia , Brassica/genética , Proteínas de Transporte/metabolismo , Regulação da Expressão Gênica de Plantas , Animais , Arabidopsis/genética , Sequência de Bases , Transporte Biológico , Proteínas de Transporte/genética , Ácido Cítrico/metabolismo , Feminino , Hidrogênio/metabolismo , Dados de Sequência Molecular , Cebolas/genética , Cebolas/fisiologia , Epiderme Vegetal/genética , Epiderme Vegetal/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Brotos de Planta/genética , Brotos de Planta/fisiologia , Plantas Geneticamente Modificadas , Potássio/metabolismo , Análise de Sequência de DNA , Estresse Fisiológico , Xenopus
15.
Plant Physiol Biochem ; 77: 23-34, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24531233

RESUMO

The response and adaptation of plants to different environmental stresses are of great interest as they provide the key to understanding the mechanisms underlying stress tolerance. In this study, the changing patterns of four endogenous hormones and various physiological and biochemical parameters of both a salt-tolerant (LA2711) and a salt-sensitive (ZS-5) tomato cultivar were examined under salt stress and non-stress conditions. Additionally, the transcription of key genes in the abscisic acid (ABA) biosynthesis and metabolism were analyzed at different time points. The results indicated that gene expression responsible for ABA biosynthesis and metabolism coincided with the hormone level, and SlNCED1 and SlCYP707A3 may play major roles in the process. LA2711 performed superior to ZS-5 on various parameters, including seed germination, Na(+) compartmentation, selective absorption of K(+), and antioxidant enzymes activity. The difference in salt tolerance between the two genotypes could be attributed to the different levels of ABA due to differences in gene expression of key genes in ABA biosynthesis and metabolism. Although gibberellin, cytokinin and auxin were involved, our results indicated that ABA signaling plays a major role in tomato salt tolerance. As compared to ZS-5, LA2711 had a higher capability to selectively absorb and redistribute K(+) and a higher tolerance to Na(+) in young leaves, which may be the main physiological mechanisms of salt tolerance.


Assuntos
Ácido Abscísico/genética , Reguladores de Crescimento de Plantas/genética , Tolerância ao Sal/genética , Cloreto de Sódio/metabolismo , Sódio/metabolismo , Solanum lycopersicum/genética , Estresse Fisiológico/genética , Ácido Abscísico/metabolismo , Antioxidantes/metabolismo , Expressão Gênica , Perfilação da Expressão Gênica , Genes de Plantas , Genótipo , Germinação/genética , Solanum lycopersicum/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Folhas de Planta , Potássio/metabolismo , Especificidade da Espécie
16.
Phys Rev Lett ; 103(16): 167003, 2009 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-19905718

RESUMO

We report the investigation of electron transport through a four-terminal graphene-superconductor hybrid system. Because of the quantum interference of the reflected holes from two graphene-superconductor interfaces with a phase difference theta, it is found that the specular Andreev reflection vanishes at theta=0 while the Andreev retroreflection disappears at theta=pi. This means that retroreflection and specular reflection can be easily controlled and separated in this device. In addition, because of the diffraction effect in the narrow graphene nanoribbon, the reflected hole can exit from both graphene terminals. As the width of nanoribbon increases, the diffraction effect gradually disappears and the reflected hole eventually exits from a particular graphene terminal depending on the type of Andreev reflection.

17.
Free Radic Res ; 42(1): 12-9, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18324519

RESUMO

Polypeptide from Chlamys farreri (PCF), a novel marine active material isolated from gonochoric Chinese scallop C. farreri, has potential antioxidant activity and protective effect against ultraviolet (UV) irradiation. The aim was to investigate whether PCF protects HaCaT cells from apoptosis induced by UVA and explore related molecular mechanisms. The results showed that PCF significantly prevented UVA-induced apoptosis of HaCaT cells. PCF not only strongly reduced the intracellular reactive oxygen species (ROS) production, but also diminished expression of acid sphingomyelinase (ASMase) and phosphorylated JNK in HaCaT cells radiated by UVA in a dose-dependent manner. Pre-treatment with ROS scavenger NAC, ASMase inhibitor desipramine or JNK inhibitor SP600125 was found to effectively prohibit UVA-induced apoptosis and desipramine markedly blocked phosphorylation of JNK. So it is concluded that PCF obviously protects HaCaT cells from apoptosis induced by UVA and protective effects may attribute to decreasing intracellular ROS level and blocking ASMase/JNK apoptotic signalling pathway.


Assuntos
Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Queratinócitos/efeitos dos fármacos , Pectinidae , Peptídeos/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Esfingomielina Fosfodiesterase/metabolismo , Raios Ultravioleta , Acetilcisteína/farmacologia , Animais , Antracenos/farmacologia , Antioxidantes/isolamento & purificação , Linhagem Celular , Desipramina/farmacologia , Relação Dose-Resposta a Droga , Ativação Enzimática , Sequestradores de Radicais Livres/farmacologia , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/antagonistas & inibidores , Queratinócitos/enzimologia , Queratinócitos/metabolismo , Queratinócitos/patologia , Queratinócitos/efeitos da radiação , Pectinidae/química , Peptídeos/isolamento & purificação , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/efeitos da radiação , Esfingomielina Fosfodiesterase/antagonistas & inibidores
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