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1.
Nature ; 575(7781): 217-223, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31666701

RESUMEN

KRAS is the most frequently mutated oncogene in cancer and encodes a key signalling protein in tumours1,2. The KRAS(G12C) mutant has a cysteine residue that has been exploited to design covalent inhibitors that have promising preclinical activity3-5. Here we optimized a series of inhibitors, using novel binding interactions to markedly enhance their potency and selectivity. Our efforts have led to the discovery of AMG 510, which is, to our knowledge, the first KRAS(G12C) inhibitor in clinical development. In preclinical analyses, treatment with AMG 510 led to the regression of KRASG12C tumours and improved the anti-tumour efficacy of chemotherapy and targeted agents. In immune-competent mice, treatment with AMG 510 resulted in a pro-inflammatory tumour microenvironment and produced durable cures alone as well as in combination with immune-checkpoint inhibitors. Cured mice rejected the growth of isogenic KRASG12D tumours, which suggests adaptive immunity against shared antigens. Furthermore, in clinical trials, AMG 510 demonstrated anti-tumour activity in the first dosing cohorts and represents a potentially transformative therapy for patients for whom effective treatments are lacking.


Asunto(s)
Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/inmunología , Piperazinas/farmacología , Piperazinas/uso terapéutico , Proteínas Proto-Oncogénicas p21(ras)/antagonistas & inhibidores , Piridinas/farmacología , Piridinas/uso terapéutico , Pirimidinas/farmacología , Pirimidinas/uso terapéutico , Animales , Antineoplásicos/administración & dosificación , Antineoplásicos/química , Proliferación Celular/efectos de los fármacos , Sinergismo Farmacológico , Humanos , Inmunoterapia , Inflamación/inducido químicamente , Inflamación/inmunología , Inflamación/patología , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Ratones , Fosforilación/efectos de los fármacos , Piperazinas/administración & dosificación , Piperazinas/química , Proteínas Proto-Oncogénicas p21(ras)/genética , Piridinas/administración & dosificación , Piridinas/química , Pirimidinas/administración & dosificación , Pirimidinas/química , Transducción de Señal/efectos de los fármacos , Resultado del Tratamiento , Microambiente Tumoral/efectos de los fármacos , Microambiente Tumoral/inmunología
2.
Nano Lett ; 24(4): 1122-1129, 2024 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-38230636

RESUMEN

Magnetic proximity-induced magnetism in paramagnetic LaNiO3 (LNO) has spurred intensive investigations in the past decade. However, no consensus has been reached so far regarding the magnetic order in LNO layers in relevant heterostructures. This paper reports a layered ferromagnetic structure for the (111)-oriented LNO/LaMnO3 (LMO) superlattices. It is found that each period of the superlattice consisted of an insulating LNO-interfacial phase (five unit cells in thickness, ∼1.1 nm), a metallic LNO-inner phase, a poorly conductive LMO-interfacial phase (three unit cells in thickness, ∼0.7 nm), and an insulating LMO-inner phase. All four of these phases are ferromagnetic, showing different magnetizations. The Mn-to-Ni interlayer charge transfer is responsible for the emergence of a layered magnetic structure, which may cause magnetic interaction across the LNO/LMO interface and double exchange within the LMO-interfacial layer. This work indicates that the proximity effect is an effective means of manipulating the magnetic state and associated properties of complex oxides.

3.
Nano Lett ; 23(10): 4258-4266, 2023 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-37158610

RESUMEN

Magnetic skyrmions are scarcely investigated for single-crystal quality films, for which skyrmions may have a remarkable performance. Even in the limited studies in this aspect, the skyrmions are usually probed by the topological Hall effect, missing important information on dynamic properties. Here, we present a comprehensive investigation on the generation/manipulation of magnetic skyrmions in La0.67Ba0.33MnO3 single-crystal films. Using the technique of magnetic force microscopy, the current-driven skyrmion dynamics are directly observed. Unlike isolated skyrmions produced by magnetic field alone, closely packed skyrmions can be generated by electric pulses in a magnetic background, with a high density (∼60/µm2) and a small size (dozens of nanometers). The threshold current moving skyrmions is ∼2.3 × 104 A/cm2, 2-3 orders of magnitude lower than that required by metallic multilayers or van der Waals ferromagnetic heterostructures. Our work demonstrates the great potential of single-crystal oxide films in developing skyrmion-based devices.

4.
J Am Chem Soc ; 143(18): 6798-6804, 2021 May 12.
Artículo en Inglés | MEDLINE | ID: mdl-33938744

RESUMEN

Spin structure of a magnetic system results from the competition of various exchange couplings. Pressure-driven spin structure evolution, through altering interatomic distance, and hence, electronic structure produces baromagnetic effect (BME), which has potential applications in sensor/actuator field. Here, we report a new spin structure(CyS-AFMb) with antiferromagnetic(AFM) nature in Fe-doped Mn0.87Fe0.13NiGe. Neutron powder diffraction (NPD) under in situ hydrostatic pressure and magnetic field was conducted to reveal the spin configuration and its instabilities. We discovered that a pressure higher than 4 kbar can induce abnormal change of Mn(Fe)-Mn(Fe) distances and transform the CyS-AFMb into a conical spiral ferromagnetic(FM) configuration(45°-CoS-FMa) with easily magnetized but shortened magnetic moment by as much as 22%. The observed BME far exceeds previous reports. Our first-principles calculations provide theoretical supports for the enhanced BME. The compressed lattice by pressure favors the 45°-CoS-FMa and significantly broadened 3d bandwidth of Mn(Fe) atoms, which leads to the shortened magnetic moment and evolution of spin structure.

5.
J Am Chem Soc ; 137(5): 1746-9, 2015 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-25629796

RESUMEN

MnCoGe-based compounds undergo a giant negative thermal expansion (NTE) during the martensitic structural transition from Ni2In-type hexagonal to TiNiSi-type orthorhombic structure. High-resolution neutron diffraction experiments revealed that the expansion of unit cell volume can be as large as ΔV/V ∼ 3.9%. The optimized compositions with concurrent magnetic and structural transitions have been studied for magnetocaloric effect. However, these materials have not been considered as NTE materials partially due to the limited temperature window of phase transition. The as-prepared MnCoGe-based compounds are quite brittle and naturally collapse into powders. By using a few percents (3-4%) of epoxy to bond the powders, we introduced residual stress in the bonded samples and thus realized the broadening of structural transition by utilizing the specific characteristics of lattice softening enforced by the stress. As a result, giant NTE (not only the linear NTE coefficient α but also the operation-temperature window) has been achieved. For example, the average α̅ as much as -51.5 × 10(-6)/K with an operating temperature window as wide as 210 K from 122 to 332 K has been observed in a bonded MnCo0.98Cr0.02Ge compound. Moreover, in the region between 250 and 305 K near room temperature, the α value (-119 × 10(-6)/K) remains nearly independent of temperature. Such an excellent performance exceeds that of most other materials reported previously, suggesting it can potentially be used as a NTE material, particularly for compensating the materials with large positive thermal expansions.

6.
Lab Invest ; 94(11): 1296-308, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25243900

RESUMEN

Sustained angiogenesis is essential for tumor growth as it provides the tumor with a network of blood vessels that supply both oxygen and essential nutrients. Limiting tumor-associated angiogenesis is a proven strategy for the treatment of human cancer. To date, the rapid detection and quantitation of tumor-associated endothelial cell (TAEC) proliferation has been challenging, largely due to the low frequency of endothelial cells (ECs) within the tumor microenvironment. In this report, we address this problem using a new multiparametric flow cytometry method capable of rapid and precise quantitation of proliferation by measuring bromodeoxyuridine (BrdUrd) uptake in mouse TAECs from established human tumor xenografts. We determined the basal proliferation labeling index of TAECs in two human tumor xenografts representing two distinct histologies, COLO 205 (colorectal cancer) and U-87 (glioblastoma). We then investigated the effects of two large-molecule antiangiogenic agents targeting different biochemical pathways. Blocking angiopoietin-Tie2 signaling with the peptide-Fc fusion protein, trebananib (AMG 386), inhibited proliferation of TAECs, whereas blocking Dll4-Notch signaling with an anti-Dll4-specific antibody induced hyperproliferation of TAECs. These pharmacodynamic studies highlight the sensitivity and utility of this flow cytometry-based method and demonstrate the value of this assay to rapidly assess the in vivo proliferative effects of angiogenesis-targeted agents on both the tumor and the associated vasculature.


Asunto(s)
Anticuerpos Neutralizantes/farmacología , Células Endoteliales/efectos de los fármacos , Citometría de Flujo/métodos , Péptidos y Proteínas de Señalización Intracelular/antagonistas & inhibidores , Proteínas de la Membrana/antagonistas & inhibidores , Receptor TIE-2/antagonistas & inhibidores , Proteínas Recombinantes de Fusión/farmacología , Animales , Anticuerpos Neutralizantes/uso terapéutico , Bromodesoxiuridina , Proliferación Celular/efectos de los fármacos , Neoplasias Colorrectales/patología , Femenino , Glioblastoma/patología , Humanos , Ratones Desnudos , Neoplasias Experimentales/tratamiento farmacológico , Neoplasias Experimentales/patología , Proteínas Recombinantes de Fusión/uso terapéutico , Ensayos Antitumor por Modelo de Xenoinjerto
7.
Nat Commun ; 15(1): 1838, 2024 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-38418810

RESUMEN

Plastic crystals as barocaloric materials exhibit the large entropy change rivalling freon, however, the limited pressure-sensitivity and large hysteresis of phase transition hinder the colossal barocaloric effect accomplished reversibly at low pressure. Here we report reversible colossal barocaloric effect at low pressure in two-dimensional van-der-Waals alkylammonium halides. Via introducing long carbon chains in ammonium halide plastic crystals, two-dimensional structure forms in (CH3-(CH2)n-1)2NH2X (X: halogen element) with weak interlayer van-der-Waals force, which dictates interlayer expansion as large as 13% and consequently volume change as much as 12% during phase transition. Such anisotropic expansion provides sufficient space for carbon chains to undergo dramatic conformation disordering, which induces colossal entropy change with large pressure-sensitivity and small hysteresis. The record reversible colossal barocaloric effect with entropy change ΔSr ~ 400 J kg-1 K-1 at 0.08 GPa and adiabatic temperature change ΔTr ~ 11 K at 0.1 GPa highlights the design of novel barocaloric materials by engineering the dimensionality of plastic crystals.

8.
Nanotechnology ; 23(26): 265202, 2012 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-22700688

RESUMEN

We here report a study of the correlation between the evolution of resistive switching and the oxygen vacancy configuration in La0.5Ca0.5MnO3 (LCMO) based memristive devices. By taking advantage of LCMO located at a phase boundary of the metal-to-insulator transition, we observe the development of the high resistive states, depending upon not only the electrical pulse magnitude but also the switching cycles. We discuss the experimental results by an oxygen migration model that involves both single isolated and clustered oxygen vacancies, which are later verified using aberration-corrected scanning transmission electron microscopy.

9.
Cancer Cell ; 6(5): 507-16, 2004 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-15542434

RESUMEN

Angiopoietin-2 (Ang2) exhibits broad expression in the remodeling vasculature of human tumors but very limited expression in normal tissues, making it an attractive candidate target for antiangiogenic cancer therapy. To investigate the functional consequences of blocking Ang2 activity, we generated antibodies and peptide-Fc fusion proteins that potently and selectively neutralize the interaction between Ang2 and its receptor, Tie2. Systemic treatment of tumor-bearing mice with these Ang2-blocking agents resulted in tumor stasis, followed by elimination of all measurable tumor in a subset of animals. These effects were accompanied by reduced endothelial cell proliferation, consistent with an antiangiogenic therapeutic mechanism. Anti-Ang2 therapy also prevented VEGF-stimulated neovascularization in a rat corneal model of angiogenesis. These results imply that specific Ang2 inhibition may represent an effective antiangiogenic strategy for treating patients with solid tumors.


Asunto(s)
Angiopoyetina 2/antagonistas & inhibidores , Angiopoyetina 2/inmunología , Anticuerpos/farmacología , Neoplasias/irrigación sanguínea , Neovascularización Patológica/prevención & control , Animales , Proliferación Celular/efectos de los fármacos , Córnea/irrigación sanguínea , Células Endoteliales/efectos de los fármacos , Femenino , Ratones , Ratones Desnudos , Trasplante de Neoplasias , Pruebas de Neutralización , Receptores Fc , Proteínas Recombinantes de Fusión/farmacología , Células Tumorales Cultivadas
10.
J Nanosci Nanotechnol ; 12(2): 1109-13, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22629904

RESUMEN

The magnetic properties and microstructure of Sm-(Co,Cu)/Fe films were investigated systematically. The addition of Cu is helpful for keeping a better multilayer structure due to the reduction of the crystallization temperature of the hard phase. With lowering the temperature, the coercivity of the Sm-(Co,Cu)/Fe films increases rapidly with a linear relationship. The Cu addition significantly improves the coercivities of the Sm-(Co,Cu)/Fe multilayer films, especially at the low temperatures. Adding the Cu as well as lowering the temperature cause a large inhomogeneity in the hard phase, and therefore a high pinning coercivity.

11.
ACS Nano ; 16(9): 14632-14643, 2022 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-36107149

RESUMEN

Modifying the crystal structure and corresponding functional properties of complex oxides by regulating their oxygen content has promising applications in energy conversion and chemical looping, where controlling oxygen migration plays an important role. Therefore, finding an efficacious and feasible method to facilitate oxygen migration has become a critical requirement for practical applications. Here, we report a compressive-strain-facilitated oxygen migration with reversible topotactic phase transformation (RTPT) in La0.5Sr0.5CoOx films based on all-solid-state electrolyte gating modulation. With the lattice strain changing from tensile to compressive strain, significant reductions in modulation duration (∼72%) and threshold voltage (∼70%) for the RTPT were observed, indicating great promotion of RTPT by compressive strain. Density functional theory calculations verify that such compressive-strain-facilitated efficient RTPT comes from significant reduction of the oxygen migration barrier in compressive-strained films. Further, ac-STEM, EELS, and sXAS investigations reveal that varying strain from tensile to compressive enhances the Co 3d band filling, thereby suppressing the Co-O hybrid bond in oxygen vacancy channels, elucidating the micro-origin of such compressive-strain-facilitated oxygen migration. Our work suggests that controlling electronic orbital occupation of Co ions in oxygen vacancy channels may help facilitate oxygen migration, providing valuable insights and practical guidance for achieving highly efficient oxygen-migration-related chemical looping and energy conversion with complex oxides.

12.
Bioorg Med Chem Lett ; 21(8): 2394-9, 2011 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-21414779

RESUMEN

The insulin-like growth factor-1 receptor (IGF-1R) plays an important role in the regulation of cell growth and differentiation, and in protection from apoptosis. IGF-1R has been shown to be an appealing target for the treatment of human cancer. Herein, we report the synthesis, structure-activity relationships (SAR), X-ray cocrystal structure and in vivo tumor study results for a series of 2,4-bis-arylamino-1,3-pyrimidines.


Asunto(s)
Inhibidores de Proteínas Quinasas/química , Pirimidinas/química , Quinolinas/síntesis química , Receptor IGF Tipo 1/antagonistas & inhibidores , Animales , Sitios de Unión , Cristalografía por Rayos X , Evaluación Preclínica de Medicamentos , Humanos , Ratones , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/farmacocinética , Pirimidinas/síntesis química , Pirimidinas/farmacocinética , Quinolinas/química , Quinolinas/farmacocinética , Receptor IGF Tipo 1/metabolismo , Relación Estructura-Actividad , Ensayos Antitumor por Modelo de Xenoinjerto
13.
Nanotechnology ; 22(25): 254008, 2011 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-21572213

RESUMEN

Resistance switching behavior has been investigated in as-prepared and oxygen-annealed polycrystalline tungsten oxide films using conductive atomic force microscopy. The oxygen-annealed film appeared more insulative than the as-prepared films. The local current distributions demonstrated the lower conductivity at the grain boundaries than at the grains in the oxygen-annealed films. Reversible resistance switching behavior only occurred at the grain surface region of the oxygen-annealed films and the resistance switching process was described by the local valence change of tungsten ions induced by electrochemical migration of protons or oxygen vacancies. This different resistance switching behavior between the grain and grain boundary surface was attributed to the different oxygen vacancy density caused by the post-annealing process. The present results would be especially meaningful for the fabrication of nanoscale resistive nonvolatile memory devices.

14.
Trials ; 18(1): 606, 2017 Dec 20.
Artículo en Inglés | MEDLINE | ID: mdl-29262859

RESUMEN

BACKGROUND: Lipoprotein-associated phospholipase A2 (Lp-PLA2), a biomarker of oxidation and inflammation, has been associated with increased coronary artery disease risk. To date, very few studies have examined the Chinese herbal drug Danshen or its extract on Lp-PLA2 in patients with stable angina pectoris. In this study, we aim to investigate the effect of Danshen extract on Lp-PLA2 level in patients with stable angina. METHODS/DESIGN: This is a randomized, single-blind, placebo-controlled, adaptive clinical trial. A total of 156 patients meeting the eligibility criteria will be randomly assigned to either the Danshen extract (DanshenDuofensuanyan injection and Danshen drop spill) group or the placebo group in a 1:1 ratio. Participants will then undergo treatment with DanshenDuofensuanyan injection or placebo (glucose) during hospitalization, followed by open-label Danshen drop spill (30 pills/day) in Danshen extract group for 60 days after discharge. Because this is an adaptive trial, two interim analyses are prospectively planned. These will be performed after one-third and two-thirds of the patients, respectively, have completed the trial. On the basis of the results of these interim analyses, a data monitoring committee will determine how to modify aspects of the study without undermining the validity and integrity of the trial. The primary outcome measure is the serum level of Lp-PLA2 in the Danshen extract group and the placebo group. The secondary outcomes include the proportion of patients who show a clinically significant change, which is defined as at least a 20-point improvement in angina frequency score on the Seattle Angina Questionnaire and the carotid intima-media thickness, which will be measured using ultrasound. Other secondary efficacy and safety outcomes will also be assessed. DISCUSSION: This study will provide evidence that Danshen extract is beneficial for stable angina and may establish a possible mechanism of Danshen treatment effects on cardiovascular disease. This study may also validate an objective blood test (LP-PLA2 level) for assessing the effectiveness of Danshen therapy in patients with stable angina pectoris. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02870764 . Registered on 13 August 2016.


Asunto(s)
1-Alquil-2-acetilglicerofosfocolina Esterasa/sangre , Angina Estable/tratamiento farmacológico , Fármacos Cardiovasculares/uso terapéutico , Medicamentos Herbarios Chinos/uso terapéutico , Adolescente , Adulto , Anciano , Angina Estable/diagnóstico , Angina Estable/enzimología , Biomarcadores/sangre , Fármacos Cardiovasculares/efectos adversos , Grosor Intima-Media Carotídeo , China , Protocolos Clínicos , Medicamentos Herbarios Chinos/efectos adversos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Proyectos de Investigación , Salvia miltiorrhiza , Método Simple Ciego , Encuestas y Cuestionarios , Factores de Tiempo , Resultado del Tratamiento , Adulto Joven
15.
Sci Rep ; 6: 25805, 2016 05 13.
Artículo en Inglés | MEDLINE | ID: mdl-27174410

RESUMEN

The ultrathin SmCo5 nanoflakes with average thickness smaller than 50 nm are prepared by a novel method of solid particle (NaCl) and surfactant co-assisted ball milling. The as-prepared nanoflakes exhibit a narrower thickness distribution of 10-50 nm and high coercivity of 23 kOe. The possible formation mechanism of nanoflakes are proposed. Temperature dependence of demagnetization curves indicate that the magnetization reversal may be controlled by both nucleation and pinning. The results of X-ray powder diffraction and magnetic measurement for aligned SmCo5 nanoflakes resin composite indicate that the nanoflakes have a high texture degree. The ultrathin thickness and high coercivity are beneficial for preparing the high performance soft/hard coupling magnets and nanocomposite magnets.

16.
Sci Rep ; 5: 13117, 2015 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-26272186

RESUMEN

The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling. The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively. The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one step high energy ball-milling, which enhances the texture degree and coercivity. In addition, the mechanism of coercivity are also studied by the temperature dependence of demagnetization curves for aligned SmCo5 nanoflakes/resin composite, the result indicates that the magnetization reversal could be controlled by co-existed mechanisms of pinning and nucleation.

17.
Sci Rep ; 5: 9668, 2015 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-25909177

RESUMEN

Memory effect of electric-field control on magnetic behavior in magnetoelectric composite heterostructures has been a topic of interest for a long time. Although the piezostrain and its transfer across the interface of ferroelectric/ferromagnetic films are known to be important in realizing magnetoelectric coupling, the underlying mechanism for nonvolatile modulation of magnetic behaviors remains a challenge. Here, we report on the electric-field control of magnetic properties in wide-band (011)-Pr0.7Sr0.3MnO3/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 heterostructures. By introducing an electric-field-induced in-plane anisotropic strain field during the cooling process from room temperature, we observe an in-plane anisotropic, nonvolatile modulation of magnetic properties in a wide-band Pr0.7Sr0.3MnO3 film at low temperatures. We attribute this anisotropic memory effect to the preferential seeding and growth of ferromagnetic (FM) domains under the anisotropic strain field. In addition, we find that the anisotropic, nonvolatile modulation of magnetic properties gradually diminishes as the temperature approaches FM transition, indicating that the nonvolatile memory effect is temperature dependent. By taking into account the competition between thermal energy and the potential barrier of the metastable magnetic state induced by the anisotropic strain field, this distinct memory effect is well explained, which provides a promising approach for designing novel electric-writing magnetic memories.

18.
Sci Rep ; 5: 18027, 2015 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-26673677

RESUMEN

The most widespread cooling techniques based on gas compression/expansion encounter environmental problems. Thus, tremendous effort has been dedicated to develop alternative cooling technique and search for solid state materials that show large caloric effects. An application of pressure to a material can cause a change in temperature, which is called the barocaloric effect. Here we report the giant barocaloric effect in a hexagonal Ni2In-type MnCoGe0.99In0.01 compound involving magnetostructural transformation, Tmstr, which is accompanied with a big difference in the internal energy due to a great negative lattice expansion(ΔV/V ~ 3.9%). High resolution neutron diffraction experiments reveal that the hydrostatic pressure can push the Tmstr to a lower temperature at a rate of 7.7 K/kbar, resulting in a giant barocaloric effect. The entropy change under a moderate pressure of 3 kbar reaches 52 J kg(-1) K(-1), which exceeds that of most materials, including the reported giant magnetocaloric effect driven by 5 T magnetic field that is available only by superconducting magnets.

19.
Mil Med ; 167(2 Suppl): 66-7, 2002 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11873521

RESUMEN

Ionizing radiation shares with proinflammatory cytokines a pathway that involves reactive oxygen species and activation of the redox-sensitive nuclear transcription factor NF-kappa B, which leads to expression of inflammatory and cell survival programs. NF-kappa B activation normally requires phosphorylation of its inhibitor I kappa B and the inhibitor's subsequent degradation by the proteasome. Nonlinear dose-response curves have been reported for both radiation-induced cytokines and NF-kappa B and I kappa B expression with maximum exposures of less than 2 Gy and greater than 4 Gy, respectively. Radiation-inhibited proteasomes function over a wide dose range, suggesting that the proteasome is a redox-sensitive target for radiation that may function along with transcription to cause nonlinear dose-response relationships for early expression of many molecules, including NF-kappa B and cytokines. These pathways are relevant to low-dose radiation effects, adaptive responses, and carcinogenesis.


Asunto(s)
Cisteína Endopeptidasas , Citocinas , Complejos Multienzimáticos , FN-kappa B , Dosis de Radiación , Animales , Ratones , Complejo de la Endopetidasa Proteasomal
20.
Sci Rep ; 4: 7075, 2014 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-25399635

RESUMEN

Abnormal percolative transport in inhomogeneous systems has drawn increasing interests due to its deviation from the conventional percolation picture. However, its nature is still ambiguous partly due to the difficulty in obtaining controllable abnormal percolative transport behaviors. Here, we report the first observation of electric-field-controlled abnormal percolative transport in (011)-Pr(0.7)(Ca(0.6)Sr(0.4))(0.3)MnO3/0.7Pb(Mg(1/3)Nb(2/3))O3-0.3PbTiO3 heterostructure. By introducing an electric-field-induced in-plane anisotropic strain-field in a phase separated PCSMO film, we stimulate a significant inverse thermal hysteresis (~ -17.5 K) and positive colossal electroresistance (~11460%), which is found to be crucially orientation-dependent and completely inconsistent with the well accepted conventional percolation picture. Further investigations reveal that such abnormal inverse hysteresis is strongly related to the preferential formation of ferromagnetic metallic domains caused by in-plane anisotropic strain-field. Meanwhile, it is found that the positive colossal electroresistance should be ascribed to the coactions between the anisotropic strain and the polarization effect from the poling of the substrate which leads to orientation and bias-polarity dependencies for the colossal electroresistance. This work unambiguously evidences the indispensable role of the anisotropic strain-field in driving the abnormal percolative transport and provides a new perspective for well understanding the percolation mechanism in inhomogeneous systems.

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