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1.
Small ; : e2406525, 2024 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-39308256

RESUMO

Design and synthesis of highly active and robust bifunctional cathode catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are of vital significance for practical applications of lithium-oxygen (Li-O2) batteries. Herein, a built-in electric field (BIEF) strategy is reported to fabricate MnTe/MnO heterostructures with a large work function difference (ΔΦ) as a bifunctional cathode catalyst in Li-O2 batteries. The MnTe/MnO heterostructures with nanosheets and microporous structures result in an abundance of exposed active sites and facilitate mass transfer. More importantly, the heterogeneous MnTe/MnO nano-interface region provides a BIEF that can trigger interfacial charge redistribution, fine-tune the adsorption energy of oxygen intermediates, and alter the morphology of discharge products to accelerate ORR/OER kinetics. Impressively, the fabricated Li-O2 batteries with MnTe/MnO cathode showcases exhibit excellent electrochemical performances, including low charging overpotential, a high specific capacity of 11930 mA h g-1, and good cycle stability over 350 cycles even with a fixed specific capacity of 500 mA h g-1 at a current density of 500 mA g-1. This work provides an avenue for the rational design of high performance heterostructure electrocatalysts toward practical applications for rechargeable Li-O2 batteries.

2.
Biochem Biophys Res Commun ; 676: 141-148, 2023 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-37516031

RESUMO

Cation diffusion facilitators (CDFs) are a large family of divalent metal transporters with broad specificities that contribute to intracellular metal homeostasis and toxicity in bacterial pathogens. Streptococcus pyogenes (Group A Streptococcus [GAS]) expresses two homologous CDF efflux transporters, MntE and CzcD, which selectively transport Mn and Zn, respectively. We discovered that the MntE- and CzcD-deficient strains exhibited a marked decrease in the viability of macrophage-differentiated THP-1 cells and neutrophils. In addition, the viability of mice infected with both deficient strains markedly increased. Consistent with a previous study, our results suggest that MntE regulates the PerR-dependent oxidative stress response by maintaining intracellular Mn levels and contributing to the growth of GAS. The maturation and proteolytic activity of streptococcal cysteine protease (SpeB), an important virulence factor in GAS, has been reported to be abrogated by zinc and copper. Zn inhibited the maturation and proteolytic activity of SpeB in the culture supernatant of the CzcD-deficient strain. Furthermore, Mn inhibited SpeB maturation and proteolytic activity in a MntE-deficient strain. Since the host pathogenicity of the SpeB-deficient strain was significantly reduced, maintenance of intracellular manganese and zinc levels in the GAS via MntE and CzcD may not only confer metal resistance to the bacterium, but may also play an essential role in its virulence. These findings provide new insights into the molecular mechanisms of pathogenicity, which allow pathogens to survive under stressful conditions associated with elevated metal ion concentrations during host infection.


Assuntos
Evasão da Resposta Imune , Streptococcus pyogenes , Animais , Camundongos , Streptococcus pyogenes/metabolismo , Metais/metabolismo , Zinco/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Cátions Bivalentes/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica
3.
Small ; 19(29): e2300246, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37013460

RESUMO

2D materials with low symmetry are explored in recent years because of their anisotropic advantage in polarization-sensitive photodetection. Herein the controllably grown hexagonal magnetic semiconducting α-MnTe nanoribbons are reported with a highly anisotropic (100) surface and their high sensitivity to polarization in a broadband photodetection, whereas the hexagonal structure is highly symmetric. The outstanding photoresponse of α-MnTe nanoribbons occurs in a broadband range from ultraviolet (UV, 360 nm) to near infrared (NIR, 914 nm) with short response times of 46 ms (rise) and 37 ms (fall), excellent environmental stability, and repeatability. Furthermore, due to highly anisotropic (100) surface, the α-MnTe nanoribbons as photodetector exhibit attractive sensitivity to polarization and high dichroic ratios of up to 2.8 under light illumination of UV-to-NIR wavelengths. These results demonstrate that 2D magnetic semiconducting α-MnTe nanoribbons provide a promising platform to design the next-generation polarization-sensitive photodetectors in a broadband range.

4.
Nano Lett ; 22(18): 7522-7526, 2022 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-36070237

RESUMO

Epitaxial Fe(Te,Se) thin films have been grown on various substrates but never been grown on magnetic layers. Here we report the epitaxial growth of fourfold Fe(Te,Se) film on a sixfold antiferromagnetic insulator, MnTe. The Fe(Te,Se)/MnTe heterostructure shows a clear superconducting transition at around 11 K, and the critical magnetic field measurement suggests the origin of the superconductivity to be bulk-like. Structural characterizations suggest that the uniaxial lattice match between Fe(Te,Se) and MnTe allows a hybrid symmetry epitaxy mode, which was recently discovered between Fe(Te,Se) and Bi2Te3. Furthermore, the Te/Fe flux ratio during deposition of the Fe(Te,Se) layer is found to be critical for its superconductivity. Now that superconducting Fe(Te,Se) can be grown on two related hexagonal platforms, Bi2Te3 and MnTe, this result opens a new possibility of combining topological superconductivity of Fe(Te,Se) with the rich physics in the intrinsic magnetic topological materials (MnTe)n(Bi2Te3)m family.

5.
Microb Pathog ; 110: 23-30, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28629722

RESUMO

Manganese is an essential micronutrient to bacteria and plays an important role in bacterial physiology. However, an excess of manganese is extremely deleterious to the cell. The manganese efflux system is used to control intracellular manganese levels by some bacteria. In this study, we have identified a cation efflux family protein (MntE) that functions as a manganese export system in Streptococcus suis serotype 2. To investigate the role of mntE in S. suis 2, a mntE deletion mutant (ΔmntE) and the corresponding complementation strain (CΔmntE) were constructed. ΔmntE displayed similar growth compared to the wild-type and complementation strains under normal growth conditions, but was defective in medium supplemented with high concentrations of manganese. In addition, the mutant was more sensitive to oxidative stress conferred by diamide. Using a competitive-infection assay in the murine infection model, we demonstrated for the first time that MntE is involved in the virulence of S. suis 2. Collectively, our data indicate that manganese homeostasis controlled by the manganese efflux system MntE is important for the pathogenesis of S. suis 2.


Assuntos
Proteínas de Bactérias/metabolismo , Manganês/metabolismo , Infecções Estreptocócicas/microbiologia , Streptococcus suis/metabolismo , Virulência , Animais , Proteínas de Bactérias/genética , Modelos Animais de Doenças , Feminino , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Homeostase , Peróxido de Hidrogênio , Camundongos , Camundongos Endogâmicos BALB C , Micronutrientes/metabolismo , Estresse Oxidativo , Alinhamento de Sequência , Análise de Sequência de Proteína , Deleção de Sequência , Streptococcus suis/genética , Streptococcus suis/crescimento & desenvolvimento , Streptococcus suis/patogenicidade
6.
Luminescence ; 32(3): 375-381, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28394484

RESUMO

The present paper reports the thermoluminescence (TL) of (ZnS)1-x (MnTe)x nanophosphors that were prepared by a wet chemical synthesis method. The structure investigated by X-ray diffraction patterns confirms the formation of a sphalerite phase whose space group was found to be F 4¯3m. From XRD, TEM and SEM analyses the average sizes of the particles were found to be 12 nm, 11 nm and 15 nm, respectively. Initially the TL intensity increased with increasing values of x because the number of luminescence centres increased; however, for higher values of x the TL intensity decreased because of the concentration quenching. Thus the TL, mechanoluminescence and photoluminescence intensities are optimum for a particular value of x, that is for x = 0.05. Thermoluminescence of the (ZnS)1-x (MnTe)x nanophosphor has not been reported previously. There were two peaks seen in the thermoluminescence glow curves in which the first peak lay at 105-100 °C and the second peak lay at 183.5-178.5 °C. The activation energies for the first and second peaks were found to be 0.45 eV and 0.75 eV, respectively.


Assuntos
Luminescência , Nanopartículas/química , Sulfetos/química , Telúrio/química , Temperatura , Compostos de Zinco/química , Medições Luminescentes , Tamanho da Partícula , Propriedades de Superfície
7.
ACS Appl Mater Interfaces ; 16(14): 17778-17786, 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38534114

RESUMO

The pressing need for data storage in the era of big data has driven the development of new storage technologies. As a prominent contender for next-generation memory, phase-change memory can effectively increase storage density through multilevel cell operation and can be applied to neuromorphic and in-memory computing. Herein, the structure and properties of Ta-doped MnTe thin films and their inherent correlations are systematically investigated. Amorphous MnTe thin films sequentially precipitated cubic MnTe2 and hexagonal Te phases with increasing temperature, causing resistance changes. Ta doping inhibited phase segregation in the films and improved their thermal stability in the amorphous state. A phase-change memory cell based on a Ta2.8%-MnTe thin film exhibited three stable resistive states with low resistive drift coefficients. The study findings reveal the possibility of regulating the two-step phase-change process in Ta-MnTe thin films, providing insight into the design of multilevel phase-change memory.

8.
ACS Appl Mater Interfaces ; 16(15): 19112-19120, 2024 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-38579811

RESUMO

Two-dimensional transition metal dichalcogenide (TMDC) heterostructure is receiving considerable attention due to its novel electronic, optoelectronic, and spintronic devices with design-oriented and functional features. However, direct design and synthesis of high-quality TMDC/MnTe heterostructures remain difficult, which severely impede further investigations of semiconductor/magnetic semiconductor devices. Herein, the synthesis of high-quality vertically stacked WS2/MnTe heterostructures is realized via a two-step chemical vapor deposition method. Raman, photoluminescence, and scanning transmission electron microscopy characterizations reveal the high-quality and atomically sharp interfaces of the WS2/MnTe heterostructure. WS2/MnTe-based van der Waals field effect transistors demonstrate high rectification behavior with rectification ratio up to 106, as well as a typical p-n electrical transport characteristic. Notably, the fabricated WS2/MnTe photodetector exhibits sensitive and broadband photoresponse ranging from UV to NIR with a maximum responsivity of 1.2 × 103 A/W, a high external quantum efficiency of 2.7 × 105%, and fast photoresponse time of ∼50 ms. Moreover, WS2/MnTe heterostructure photodetectors possess a broadband image sensing capability at room temperature, suggesting potential applications in next-generation high-performance and broadband image sensing photodetectors.

9.
ACS Nano ; 18(34): 23508-23517, 2024 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-39137306

RESUMO

Two-dimensional ferromagnetic/antiferromagnetic (2D-FM/AFM) heterostructures are of great significance to realize the application of spintronic devices such as miniaturization, low power consumption, and high-density information storage. However, traditional mechanical stacking can easily damage the crystal quality or cause chemical contamination residues for 2D materials, which can result in weak interface coupling and difficulty in device regulation. Chemical vapor deposition (CVD) is an effective way to achieve a high-quality heterostructure interface. Herein, high-quality interface 2D-FM/AFM Cr7Te8/MnTe vertical heterostructures were successfully synthesized via a one-pot CVD method. Moreover, the atomic-scale structural scanning transmission electron microscope (STEM) characterization shows that the interface of the vertical heterostructure is clear and flat without an excess interface layer. Compared to the parent Cr7Te8, the coercivity (HC) of the high-quality interface Cr7Te8/MnTe heterostructure is significantly reduced as the thickness of MnTe increases, with a maximum decrease of 74.5% when the thickness of the MnTe nanosheet is around 30 nm. Additionally, the HC of the Cr7Te8/MnTe heterostructure can also be regulated by applying a gate voltage, and the HC increases or decreases with increasing positive or negative gate voltages. Thus, the effective regulation of HC is essential to improving the performance of advanced spintronic devices (e.g., MRAM and magnetic sensors). Our work will provide ideas for spin controlling and device application of 2D-FM/AFM heterostructures.

10.
Cryobiology ; 67(3): 394-7, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23981864

RESUMO

The aim of this study was to assess whether a cell permeable superoxide dismutase agent such as MnTE, can further improve the quality of frozen/thawed semen sample using a commercially optimized sperm cryopreservation media (Bioxcell). Bioxcell was supplemented with different concentration of MnTE. Sperm membrane integrity, motility, viability and acrosomal status were assessed after freezing. Optimized concentration of MnTE was defined and used to assess fertilization and developmental potential. 0.1 µM MnTE significantly improved membrane integrity while 0.01 µM MnTE significantly improved acrosomal integrity post thawing. Addition of 0.01 µM MnTE also improved blastocyst formation rate. Supplementation of commercially optimized cryopreservation media with MnTE further improves the quality of goat frozen semen sample and may have important consequence of future embryo development. This effect may be attributed to cell permeable behavior of this antioxidant which may protect sperm genome from ROS-induced DNA damage.


Assuntos
Antioxidantes/metabolismo , Criopreservação/veterinária , Crioprotetores/metabolismo , Preservação do Sêmen/veterinária , Espermatozoides/citologia , Superóxido Dismutase/metabolismo , Animais , Blastômeros/citologia , Criopreservação/métodos , Feminino , Fertilização in vitro/veterinária , Cabras , Humanos , Masculino , Permeabilidade , Preservação do Sêmen/métodos , Espermatozoides/efeitos dos fármacos
11.
ACS Appl Mater Interfaces ; 15(36): 42730-42736, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37640668

RESUMO

MnTe is considered a promising candidate for next-generation phase change materials owing to the reversible and nonvolatile phase transformation between its α and ß' phases by irradiation of a nanosecond laser or application of a pulse voltage. In this work, for a faster phase control of MnTe, the response of metastable ß-MnTe thin films to femtosecond (fs) laser irradiation was investigated. Using ultrafast optical spectroscopy, we inferred transient phase transformation. Moreover, with an increase in laser-excitation fluence, a nonvolatile structural change from the ß to α phase was experimentally observed by Raman spectroscopy and transmission electron microscopy without ablation damage on the sample. The observation results strongly suggest that the fs-laser-induced ß â†’ α phase transformation proceeds through the nucleation and growth mode without a large temperature increase.

12.
Int J Mol Sci ; 13(8): 9785-9797, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22949830

RESUMO

MnTE-2-PyP, a superoxide dismutase mimetic, inhibited OVA-induced airway inflammation in mice suggesting an effect on Th2 responsiveness. Thus, we hypothesized that MnTE-2-PyP may alter dendritic cell-Th2 interactions. Bone marrow derived dendritic cells (DC) and OVA(323-339)-specific Th2 cells were cultured separately in the presence or absence of MnTE-2-PyP for 3 days prior to the co-culturing of the two cell types in the presence of an OVA(323-339) peptide and in some cases stimulated with CD3/CD28. MnTE-2-PyP-pretreated DC inhibited IL-4, IL-5 and IFNγ production and inhibited Th2 cell proliferation in the DC-Th2 co-culturing system in the presence of the OVA(323-339) peptide. Similar results were obtained using the CD3/CD28 cell-activation system; the addition of MnTE-2-PyP inhibited Th2 cell proliferation. MnTE-2-PyP suppressed CD25 expression on OVA-specific Th2 cells, which implied that MnTE-2-PyP can inhibit the activation of Th2 cells. MnTE-2-PyP also down-regulated co-stimulatory molecules: CD40, CD80 and CD86 on immature DC. Our studies suggest that the major mechanism by which MnTE-2-PyP inhibits airway inflammation is by acting on the DC and suppressing Th2 cell proliferation and activation.


Assuntos
Antioxidantes/farmacologia , Asma/imunologia , Células Dendríticas/imunologia , Modelos Animais de Doenças , Metaloporfirinas/farmacologia , Células Th2/imunologia , Animais , Asma/tratamento farmacológico , Asma/patologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Células Dendríticas/citologia , Células Dendríticas/efeitos dos fármacos , Citometria de Fluxo , Camundongos , Camundongos Endogâmicos BALB C , Ovalbumina/farmacologia , Células Th2/efeitos dos fármacos , Células Th2/patologia
13.
Res Rep Trop Med ; 12: 247-261, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34849046

RESUMO

The maternal and neonatal tetanus elimination (MNTE) program was envisaged by the World Health Organization to overcome the mortality and morbidity caused by maternal and neonatal tetanus (MNT). Although preventable by simple cost-effective practices like universal immunization, clean delivery practices, and healthy umbilical cord care, as of date MNT is still prevalent in 12 developing countries of Asia and Africa. Definitive approaches need to be microplanned by these countries to successfully accomplish the three stages of MNTE, ie, achieving, validating, and sustaining. Once a country achieves MNTE, this status is required to be validated and sustained according to the high-risk and low-risk categorization of the districts. The three-pronged strategies for achieving and sustaining MNTE include (a) rigorous immunization of women of reproductive age with tetanus toxoid-containing vaccines, (b) strengthening of clean delivery services for pregnant women, and (c) effective surveillance for MNT. Although the deadlines for achieving MNTE globally have been missed many times, yet there has been a significant progress to date as evident by 80% reduction in countries requiring validation for MNTE (59 countries in 1999 to 12 countries in 2020). Huge strides have been made in the overall coverage of two doses of tetanus toxoid (13.79% to 65.27%), neonates being protected at birth (12% to 88%), global coverage of third-dose DPT (more than doubled), and reduction of 88% estimated deaths due to NT in the last four decades. Identification of the most vulnerable populations, systematic planning at all levels of health care, involvement of local community support, tackling the implementation gap, strong political will, good financial support, and continued robust surveillance will go a long way in achieving MNTE.

14.
Antioxidants (Basel) ; 9(6)2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32512786

RESUMO

Prostate cancer patients are often treated with radiotherapy. MnTE-2-PyP, a superoxide dismutase (SOD) mimic, is a known radioprotector of normal tissues. Our recent work demonstrated that MnTE-2-PyP also inhibits prostate cancer progression with radiotherapy; however, the mechanisms remain unclear. In this study, we identified that MnTE-2-PyP-induced intracellular H2O2 levels are critical in inhibiting the growth of PC3 and LNCaP cells, but the increased H2O2 levels affected the two cancer cells differently. In PC3 cells, many proteins were thiol oxidized with MnTE-2-PyP treatment, including Ser/Thr protein phosphatase 1 beta catalytic subunit (PP1CB). This resulted in reduced PP1CB activity; however, overall cell cycle progression was not altered, so this is not the main mechanism of PC3 cell growth inhibition. High H2O2 levels by MnTE-2-PyP treatment induced nuclear fragmentation, which could be synergistically enhanced with radiotherapy. In LNCaP cells, thiol oxidation by MnTE-2-PyP treatment was not observed previously and, similarly to PC3 cells, there was no effect of MnTE-2-PyP treatment on cell cycle progression. However, in LNCaP cells, MnTE-2-PyP caused an increase in low RNA population and sub-G1 population of cells, which indicates that MnTE-2-PyP treatment may cause cellular quiescence or direct cancer cell death. The protein oxidative modifications and mitotic catastrophes caused by MnTE-2-PyP may be the major contributors to cell growth inhibition in PC3 cells, while in LNCaP cells, tumor cell quiescence or cell death appears to be major factors in MnTE-2-PyP-induced growth inhibition.

15.
Free Radic Biol Med ; 152: 255-270, 2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32222469

RESUMO

Radiation therapy is a frequently used treatment for prostate cancer patients. Manganese (III) meso-tetrakis (N-ethylpyridinium-2-yl) porphyrin (MnTE-2-PyP or T2E or BMX-010) and other similar manganese porphyrin compounds that scavenge superoxide molecules have been demonstrated to be effective radioprotectors and prevent the development of radiation-induced fibrosis (RIF). However, understanding the molecular pathway changes associated with these compounds remains limited for radioprotection. Recent RNA-sequencing data from our laboratory revealed that MnTE-2-PyP treatment activated the nuclear factor erythroid 2-related factor 2 (NRF2) signaling pathway. Therefore, we hypothesize that MnTE-2-PyP protects the prostate from RIF by activating the NRF2 signaling pathway. We identified that MnTE-2-PyP is a post-translational activator of NRF2 signaling in prostate fibroblast cells, which plays a major role in fibroblast activation and myofibroblast differentiation. The mechanism of NRF2 activation involves an increase in hydrogen peroxide and a corresponding decrease in kelch-like ECH-associated protein 1 (KEAP1) levels. Activation of NRF2 signaling leads to an increase in expression of NAD(P)H dehydrogenase [quinone] 1 (NQO1), nicotinamide adenine dinucleotide (NAD+) levels, sirtuin activity (nuclear and mitochondrial), and superoxide dismutase 2 (SOD2) expression/activity. Increase in mitochondrial sirtuin activity correlates with a decrease in SOD2 (K122) acetylation. This decrease in SOD2 K122 acetylation correlates with an increase in SOD2 activity and mitochondrial superoxide scavenging capacity. Further, in human primary prostate fibroblast cells, the NRF2 pathway plays a major role in the fibroblast to myofibroblast transformation, which is responsible for the fibrotic phenotype. In the context of radiation protection, MnTE-2-PyP fails to prevent fibroblast to myofibroblast transformation in the absence of NRF2 signaling. Collectively, our results indicate that the activation of the NRF2 signaling pathway by MnTE-2-PyP is at least a partial mechanism of radioprotection in prostate fibroblast cells.


Assuntos
Metaloporfirinas , Porfirinas , Sirtuínas , Fibrose , Humanos , Proteína 1 Associada a ECH Semelhante a Kelch , Masculino , Manganês , Metaloporfirinas/farmacologia , Fator 2 Relacionado a NF-E2/genética , Próstata , Transdução de Sinais , Superóxido Dismutase
16.
Redox Biol ; 20: 307-320, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30390545

RESUMO

Negative Pressure Wound Therapy (NPWT), a widely used modality in the management of surgical and trauma wounds, offers clear benefits over conventional wound healing strategies. Despite the wide-ranging effects ascribed to NPWT, the precise molecular mechanisms underlying the accelerated healing supported by NPWT remains poorly understood. Notably, cellular redox status-a product of the balance between cellular reactive oxygen species (ROS) production and anti-oxidant defense systems-plays an important role in wound healing and dysregulation of redox homeostasis has a profound effect on wound healing. Here we investigated potential links between the use of NPWT and the regulation of antioxidant mechanisms. Using patient samples and a rodent model of acute injury, we observed a significant accumulation of MnSOD protein as well as higher enzymatic activity in tissues upon NPWT. As a proof of concept and to outline the important role of SOD activity in wound healing, we replaced NPWT by the topical application of a MnSOD mimetic, Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP5+, MnE, BMX-010, AEOl10113) in the rodent model. We observed that MnE is a potent wound healing enhancer as it appears to facilitate the formation of new tissue within the wound bed and consequently advances wound closure by two days, compared to the non-treated animals. Taken together, these results show for the first time a link between NPWT and regulation of antioxidant mechanism through the maintenance of MnSOD activity. Additionally this discovery outlined the potential role of MnSOD mimetics as topical agents enhancing wound healing.


Assuntos
Tratamento de Ferimentos com Pressão Negativa , Superóxido Dismutase/metabolismo , Cicatrização , Administração Tópica , Animais , Antioxidantes/metabolismo , Mimetismo Biológico , Biomimética , Terapia Combinada , Gerenciamento Clínico , Modelos Animais de Doenças , Ativação Enzimática , Humanos , Metaloporfirinas/administração & dosagem , Ratos , Superóxido Dismutase/administração & dosagem , Resultado do Tratamento , Cicatrização/efeitos dos fármacos
17.
ACS Appl Mater Interfaces ; 10(30): 25519-25528, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-29979034

RESUMO

MnTe compounds show great potential for thermoelectric applications in the intermediate temperature range (500-800 K) because of their large Seebeck coefficient and intrinsically low thermal conductivity. So far, the existing methods for the synthesis of MnTe compounds remain constrained to multistep processes that are time- and energy-intensive. Herein, we demonstrate ultrafast synthesis of high-density bulk MnTe compounds using a combination of self-propagating high-temperature synthesis (SHS) and plasma activated sintering. The entire synthesis and processing procedure takes less than 1 h. The thermodynamic consideration suggests that the SHS process includes two steps: (1) Mn + 2Te → MnTe2 + Q1 and (2) MnTe2 → MnTe + Te. With the heat released by step (1), the process moved in cycle and finished in a rather short time. The effect of extra Mn content on the structure and thermoelectric properties was investigated. There is some solubility limit of extra Mn in the Mn1+ xTe compound. The extra Mn occupy interstitial sites, leading to a decrease of carrier concentration while enhancing Seebeck coefficient and decreasing thermal conductivity. Low-temperature heat capacity data indicates that the Mn1.06Te compound has a high effective mass of 8.34 m0 and a low Debye temperature of 186 K, which are beneficial for the large Seebeck coefficient and low thermal conductivity. Therefore, the maximum ZT value reaches 0.57 at 850 K for the Mn1.06Te compound.

18.
Antioxid Redox Signal ; 29(13): 1196-1214, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-29390861

RESUMO

AIMS: We aim here to demonstrate that radiation (RT) enhances tumor sensitization by only those Mn complexes that are redox active and cycle with ascorbate (Asc), thereby producing H2O2 and utilizing it subsequently in protein S-glutathionylation in a glutathione peroxidase (GPx)-like manner. In turn, such compounds affect cellular redox environment, described by glutathione disulfide (GSSG)/glutathione (GSH) ratio, and tumor growth. To achieve our goal, we tested several Mn complexes of different chemical and physical properties in cellular and animal flank models of 4T1 breast cancer cell. Four other cancer cell lines were used to substantiate key findings. RESULTS: Joint administration of cationic Mn porphyrin (MnP)-based redox active compounds, MnTE-2-PyP5+ or MnTnBuOE-2-PyP5+ with RT and Asc contributes to high H2O2 production in cancer cells and tumor, which along with high MnP accumulation in cancer cells and tumor induces the largest suppression of cell viability and tumor growth, while increasing GSSG/GSH ratio and levels of total S-glutathionylated proteins. Redox-inert MnP, MnTBAP3- and two other different types of redox-active Mn complexes (EUK-8 and M40403) were neither efficacious in the cellular nor in the animal model. Such outcome is in accordance with their inability to catalyze Asc oxidation and mimic GPx. INNOVATION: We provided here the first evidence how structure-activity relationship between the catalytic potency and the redox properties of Mn complexes controls their ability to impact cellular redox environment and thus enhance the radiation and ascorbate-mediated tumor suppression. CONCLUSIONS: The interplay between the accumulation of cationic MnPs and their potency as catalysts for oxidation of Asc, protein cysteines, and GSH controls the magnitude of their anticancer therapeutic effects.


Assuntos
Antineoplásicos/farmacologia , Ácido Ascórbico/metabolismo , Manganês/farmacologia , Estruturas Metalorgânicas/farmacologia , Neoplasias/metabolismo , Neoplasias/radioterapia , Animais , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Feminino , Humanos , Manganês/química , Estruturas Metalorgânicas/química , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias/patologia , Oxirredução , Relação Estrutura-Atividade
19.
Vaccine ; 36(25): 3573-3575, 2018 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-28427847

RESUMO

This article presents the World Health Organization's (WHO) recommendations on the use of tetanus toxoid (TT) vaccines excerpted from the WHO position paper on tetanus vaccines - February 2017, published in the Weekly Epidemiological Record [1]. This position paper replaces the May 2006 WHO position paper on tetanus vaccines (Tetanus vaccines: WHO position paper, 2006). The position paper summarizes the recent developments in the field of tetanus prevention and provides revised guidance on the optimal timing of recommended tetanus vaccine booster doses. Footnotes to this paper provide a number of core references including references to grading tables that assess the quality of the scientific evidence, and to the evidence-to-recommendation table. In accordance with its mandate to provide guidance to Member States on health policy matters, WHO issues a series of regularly updated position papers on vaccines and combinations of vaccines against diseases that have an international public health impact. These papers are concerned primarily with the use of vaccines in large-scale immunization programmes; they summarize essential background information on diseases and vaccines, and conclude with WHO's current position on the use of vaccines in the global context. Recommendations on the use of TT-containing vaccines (TTCVs) were discussed by SAGE in October 2016; evidence presented at the meeting can be accessed at: http://www.who.int/immunization/sage/meetings/2016/october/presentations_background_docs/en/.


Assuntos
Política de Saúde , Guias de Prática Clínica como Assunto , Toxoide Tetânico/administração & dosagem , Tétano/prevenção & controle , Vacinação , Adolescente , Adulto , Feminino , Humanos , Programas de Imunização , Esquemas de Imunização , Imunização Secundária/métodos , Lactente , Gravidez , Tétano/imunologia , Tétano/virologia , Organização Mundial da Saúde
20.
Antioxidants (Basel) ; 6(4)2017 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-29113120

RESUMO

Pelvic radiation for cancer therapy can damage a variety of normal tissues. In this study, we demonstrate that radiation causes acute changes to pelvic fibroblasts such as the transformation to myofibroblasts and the induction of senescence, which persist months after radiation. The addition of the manganese porphyrin, MnTE-2-PyP, resulted in protection of these acute changes in fibroblasts and this protection persisted months following radiation exposure. Specifically, at two months post-radiation, MnTE-2-PyP inhibited the number of α-smooth muscle actin positive fibroblasts induced by radiation and at six months post-radiation, MnTE-2-PyP significantly reduced collagen deposition (fibrosis) in the skin and bladder tissues of irradiated mice. Radiation also resulted in changes to T cells. At two months post-radiation, there was a reduction of Th1-producing splenocytes, which resulted in reduced Th1:Th2 ratios. MnTE-2-PyP maintained Th1:Th2 ratios similar to unirradiated mice. At six months post-radiation, increased T cells were observed in the adipose tissues. MnTE-2-PyP treatment inhibited this increase. Thus, MnTE-2-PyP treatment maintains normal fibroblast function and T cell immunity months after radiation exposure. We believe that one of the reasons MnTE-2-PyP is a potent radioprotector is due to its protection of multiple cell types from radiation damage.

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