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1.
Ann Oncol ; 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38906254

RESUMO

BACKGROUND: After surgical resection of pancreatic ductal adenocarcinoma (PDAC), patients are predominantly treated with adjuvant chemotherapy, commonly consisting of gemcitabine-based regimens or the modified FOLFIRINOX regimen (mFFX). While mFFX has been shown to be more effective than gemcitabine-based regimens, it is also associated with higher toxicity. Current treatment decisions are based on patient performance status rather than on the molecular characteristics of the tumor. To address this gap, the goal of this study was to develop drug-specific transcriptomic signatures for personalized chemotherapy treatment. PATIENTS AND METHODS: We used PDAC datasets from preclinical models, encompassing chemotherapy response profiles for the mFFX-regimen components. From them we identified specific gene transcripts associated with chemotherapy response. Three transcriptomic AI-signatures were obtained by combining Independent Component Analysis, Least Absolute Shrinkage and the Selection Operator-Random Forest approach. We integrated a previously developed gemcitabine signature with three newly developed ones. The machine learning strategy employed to enhance these signatures incorporates transcriptomic features from the tumor microenvironment, leading to the development of the Pancreas-View tool ultimately clinically validated in a cohort of 343 patients from the PRODIGE-24/CCTG PA6 trial. RESULTS: Patients who were predicted to be sensitive to the administered drugs (n=164; 47.8%) had longer disease-free survival (DFS) than the other patients. The median DFS in the mFFX sensitive group treated with mFFX was 50.0 months (stratified HR: 0.31; 95% CI, 0.21-0.44; p<0.001) and 33.7 months (stratified HR: 0.40; 95% CI, 0.17-0.59; p<0.001) in the gemcitabine sensitive group when treated with gemcitabine. Comparatively patients with signature predictions unmatched with the treatments (n=86; 25.1%) or those resistant to all drugs (n=93; 27.1%) had shorter DFS (10.6 and 10.8 months, respectively). CONCLUSIONS: This study presents a transcriptome-based tool that was developed using preclinical models and machine learning to accurately predict sensitivity to mFFX and gemcitabine.

2.
Nanotechnology ; 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38744268

RESUMO

The field of nanoscale magnetic resonance imaging (NanoMRI) was started 30 years ago. It was motivated by the desire to image single molecules and molecular assemblies, such as proteins and virus particles, with near-atomic spatial resolution and on a length scale of 100 nm. Over the years, the NanoMRI field has also expanded to include the goal of useful high-resolution nuclear magnetic resonance (NMR) spectroscopy of molecules under ambient conditions, including samples up to the micron-scale. The realization of these goals requires the development of spin detection techniques that are many orders of magnitude more sensitive than conventional NMR and MRI, capable of detecting and controlling nanoscale ensembles of spins. Over the years, a number of different technical approaches to NanoMRI have emerged, each possessing a distinct set of capabilities for basic and applied areas of science. The goal of this roadmap article is to report the current state of the art in NanoMRI technologies, outline the areas where they are poised to have impact, identify the challenges that lie ahead, and propose methods to meet these challenges. This roadmap also shows how developments in NanoMRI techniques can lead to breakthroughs in emerging quantum science and technology applications. .

3.
Nano Lett ; 23(11): 5055-5060, 2023 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-37235476

RESUMO

Y3Fe5O12 is arguably the best magnetic material for magnonic quantum information science (QIS) because of its extremely low damping. We report ultralow damping at 2 K in epitaxial Y3Fe5O12 thin films grown on a diamagnetic Y3Sc2Ga3O12 substrate that contains no rare-earth elements. Using these ultralow damping YIG films, we demonstrate for the first time strong coupling between magnons in patterned YIG thin films and microwave photons in a superconducting Nb resonator. This result paves the road toward scalable hybrid quantum systems that integrate superconducting microwave resonators, YIG film magnon conduits, and superconducting qubits into on-chip QIS devices.

4.
Nano Lett ; 22(3): 1115-1121, 2022 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-35099980

RESUMO

Engineering magnetic anisotropy in a ferro- or ferrimagnetic (FM) thin film is crucial in a spintronic device. One way to modify the magnetic anisotropy is through the surface of the FM thin film. Here, we report the emergence of a perpendicular magnetic anisotropy (PMA) induced by interfacial interactions in a heterostructure comprised of a garnet ferrimagnet, Y3Fe5O12 (YIG), and a low-symmetry, high spin-orbit coupling (SOC) transition metal dichalcogenide, WTe2. At the same time, we also observed an enhancement in Gilbert damping in the WTe2-covered YIG area. Both the magnitude of interface-induced PMA and the Gilbert damping enhancement have no observable WTe2 thickness dependence down to a single quadruple layer, indicating that the interfacial interaction plays a critical role. The ability of WTe2 to enhance the PMA in FM thin film, combined with its previously reported capability to generate out-of-plane damping like spin torque, makes it desirable for magnetic memory applications.

5.
Nano Lett ; 21(24): 10208-10214, 2021 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-34870431

RESUMO

We demonstrate a high-quality spin-orbit torque nano-oscillator comprised of spin wave modes confined by the magnetic field by the strongly inhomogeneous dipole field of a nearby micromagnet. This approach enables variable spatial confinement and systematic tuning of magnon spectrum and spectral separations for studying the impact of multimode interactions on auto-oscillations. We find these dipole-field-localized spin wave modes exhibit good characteristic properties as auto-oscillators─narrow line width and large amplitude─while persisting up to room temperature. We find that the line width of the lowest-lying localized mode is approximately proportional to temperature in good agreement with theoretical analysis of the impact of thermal fluctuations. This demonstration of a clean oscillator with tunable properties provides a powerful tool for understanding the fundamental limitations and line width contributions to improve future spin-Hall oscillators.

6.
Ann Oncol ; 32(2): 250-260, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33188873

RESUMO

BACKGROUND: Chemotherapy is the only systemic treatment approved for pancreatic ductal adenocarcinoma (PDAC), with a selection of regimens based on patients' performance status and expected efficacy. The establishment of a potent stratification associated with chemotherapeutic efficacy could potentially improve prognosis by tailoring treatments. PATIENTS AND METHODS: Concomitant chemosensitivity and genome-wide RNA profiles were carried out on preclinical models (primary cell cultures and patient-derived xenografts) derived from patients with PDAC included in the PaCaOmics program (NCT01692873). The RNA-based stratification was tested in a monocentric cohort and validated in a multicentric cohort, both retrospectively collected from resected PDAC samples (67 and 368 patients, respectively). Forty-three (65%) and 203 (55%) patients received adjuvant gemcitabine in the monocentric and the multicentric cohorts, respectively. The relationships between predicted gemcitabine sensitivity and patients' overall survival (OS) and disease-free survival were investigated. RESULTS: The GemPred RNA signature was derived from preclinical models, defining gemcitabine sensitive PDAC as GemPred+. Among the patients who received gemcitabine in the test and validation cohorts, the GemPred+ patients had a higher OS than GemPred- (P = 0.046 and P = 0.00216). In both cohorts, the GemPred stratification was not associated with OS among patients who did not receive gemcitabine. Among gemcitabine-treated patients, GemPred+ patients had significantly higher OS than the GemPred-: 91.3 months [95% confidence interval (CI): 61.2-not reached] versus 33 months (95% CI: 24-35.2); hazard ratio 0.403 (95% CI: 0.221-0.735, P = 0.00216). The interaction test for gemcitabine and GemPred+ stratification was significant (P = 0.0245). Multivariate analysis in the gemcitabine-treated population retained an independent predictive value. CONCLUSION: The RNA-based GemPred stratification predicts the benefit of adjuvant gemcitabine in PDAC patients.


Assuntos
Adenocarcinoma , Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/genética , Carcinoma Ductal Pancreático/tratamento farmacológico , Carcinoma Ductal Pancreático/genética , Quimioterapia Adjuvante , Desoxicitidina/análogos & derivados , Humanos , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/genética , Estudos Retrospectivos , Transcriptoma , Gencitabina
7.
Nano Lett ; 20(10): 7257-7262, 2020 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-32955896

RESUMO

Nonlocal spin transport using lateral structures is attractive for spintronic devices. Typically, a spin current is generated by a ferromagnetic (FM) or a heavy metal (HM) electrode in a nonlocal structure, which can be detected by another FM or HM electrode. Here, we report a new nonlocal spin injection scheme using uniform-mode ferromagnetic resonance (FMR) spin pumping in Pt/Y3Fe5O12 (YIG) lateral structures. This scheme is enabled by well-separated resonant fields of Pt/YIG and bare YIG due to substantial change of anisotropy in YIG films induced by a Pt overlayer, allowing for clearly distinguishable local and nonlocal spin pumping. Our results show that the spin decay length of nonlocal uniform-mode spin pumping in 20 nm YIG films is 2.1 µm at room temperature.

8.
Phys Rev Lett ; 124(1): 017201, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31976706

RESUMO

We lay the foundation for determining the microscopic spin interactions in two-dimensional (2D) ferromagnets by combining angle-dependent ferromagnetic resonance (FMR) experiments on high quality CrI_{3} single crystals with theoretical modeling based on symmetries. We discover that the Kitaev interaction is the strongest in this material with K∼-5.2 meV, 25 times larger than the Heisenberg exchange J∼-0.2 meV, and responsible for opening the ∼5 meV gap at the Dirac points in the spin-wave dispersion. Furthermore, we find that the symmetric off-diagonal anisotropy Γ∼-67.5 µeV, though small, is crucial for opening a ∼0.3 meV gap in the magnon spectrum at the zone center and stabilizing ferromagnetism in the 2D limit. The high resolution of the FMR data further reveals a µeV-scale quadrupolar contribution to the S=3/2 magnetism. Our identification of the underlying exchange anisotropies opens paths toward 2D ferromagnets with higher T_{C} as well as magnetically frustrated quantum spin liquids based on Kitaev physics.

9.
Phys Rev Lett ; 124(25): 257202, 2020 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-32639765

RESUMO

Interfacial magnetic anisotropy in magnetic insulators has been largely unexplored. Recently, interface-induced skyrmions and electrical control of magnetization have been discovered in insulator-based heterostructures, which demand a thorough understanding of interfacial interactions in these materials. We observe a substantial, tunable interfacial magnetic anisotropy between Tm_{3}Fe_{5}O_{12} epitaxial thin films and fifteen nonmagnetic materials spanning a significant portion of the periodic table, which we attribute to Rashba spin-orbit coupling. Our results show a clear distinction between nonmagnetic capping layers from the d block and the p block. This work offers a new path for controlling magnetic phases in magnetic insulators for low-loss spintronic applications.

10.
Nano Lett ; 19(8): 5683-5688, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31310542

RESUMO

Electrical detection of topological magnetic textures such as skyrmions is currently limited to conducting materials. Although magnetic insulators offer key advantages for skyrmion technologies with high speed and low loss, they have not yet been explored electrically. Here, we report a prominent topological Hall effect in Pt/Tm3Fe5O12 bilayers, where the pristine Tm3Fe5O12 epitaxial films down to 1.25 unit cell thickness allow for tuning of topological Hall stability over a broad range from 200 to 465 K through atomic-scale thickness control. Although Tm3Fe5O12 is insulating, we demonstrate the detection of topological magnetic textures through a novel phenomenon: "spin-Hall topological Hall effect" (SH-THE), where the interfacial spin-orbit torques allow spin-Hall-effect generated spins in Pt to experience the unique topology of the underlying skyrmions in Tm3Fe5O12. This novel electrical detection phenomenon paves a new path for utilizing a large family of magnetic insulators in future skyrmion technologies.

11.
Ann Oncol ; 30(12): 1959-1968, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31562758

RESUMO

BACKGROUND: Patients with metastatic pancreatic cancer often have a detriment in health-related quality of life (HRQoL). In the randomized, double-blind, phase III POLO trial progression-free survival was significantly longer with maintenance olaparib, a poly(ADP-ribose) polymerase inhibitor, than placebo in patients with a germline BRCA1 and/or BRCA2 mutation (gBRCAm) and metastatic pancreatic cancer whose disease had not progressed during first-line platinum-based chemotherapy. The prespecified HRQoL evaluation is reported here. PATIENTS AND METHODS: Patients were randomized to receive maintenance olaparib (300 mg b.i.d.; tablets) or placebo. HRQoL was assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30-item module at baseline, every 4 weeks until disease progression, at discontinuation, and 30 days after last dose. Scores ranged from 0 to 100; a ≥10-point change or difference between arms was considered clinically meaningful. Adjusted mean change from baseline was analysed using a mixed model for repeated measures. Time to sustained clinically meaningful deterioration (TSCMD) was analysed using a log-rank test. RESULTS: Of 154 randomized patients, 89 of 92 olaparib-arm and 58 of 62 placebo-arm patients were included in HRQoL analyses. The adjusted mean change in Global Health Status (GHS) score from baseline was <10 points in both arms and there was no significant between-group difference [-2.47; 95% confidence interval (CI) -7.27, 2.33; P = 0.31]. Analysis of physical functioning scores showed a significant between-group difference (-4.45 points; 95% CI -8.75, -0.16; P = 0.04). There was no difference in TSCMD for olaparib versus placebo for GHS [P = 0.25; hazard ratio (HR) 0.72; 95% CI 0.41, 1.27] or physical functioning (P = 0.32; HR 1.38; 95% CI 0.73, 2.63). CONCLUSIONS: HRQoL was preserved with maintenance olaparib treatment with no clinically meaningful difference compared with placebo. These results support the observed efficacy benefit of maintenance olaparib in patients with a gBRCAm and metastatic pancreatic cancer. CLINCALTRIALS.GOV NUMBER: NCT02184195.


Assuntos
Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias Pancreáticas/tratamento farmacológico , Ftalazinas/administração & dosagem , Piperazinas/administração & dosagem , Inibidores de Poli(ADP-Ribose) Polimerases/administração & dosagem , Adulto , Idoso , Método Duplo-Cego , Feminino , Mutação em Linhagem Germinativa/genética , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/genética , Recidiva Local de Neoplasia/patologia , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Ftalazinas/efeitos adversos , Piperazinas/efeitos adversos , Inibidores de Poli(ADP-Ribose) Polimerases/efeitos adversos , Intervalo Livre de Progressão , Qualidade de Vida
12.
Am J Gastroenterol ; 114(1): 155-164, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30353057

RESUMO

OBJECTIVES: Intraductal papillary mucinous neoplasms (IPMNs) are associated with risk of pancreatic ductal adenocarcinoma (PDAC). It is unclear if an IPMN in individuals at high risk of PDAC should be considered as a positive screening result or as an incidental finding. Stratified familial pancreatic cancer (FPC) populations were used to determine if IPMN risk is linked to familial risk of PDAC. METHODS: This is a cohort study of 321 individuals from 258 kindreds suspected of being FPC and undergoing secondary screening for PDAC through the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC). Computerised tomography, endoscopic ultrasound of the pancreas and magnetic resonance imaging were used. The risk of being a carrier of a dominant mutation predisposing to pancreatic cancer was stratified into three even categories (low, medium and high) based on: Mendelian probability, the number of PDAC cases and the number of people at risk in a kindred. RESULTS: There was a median (interquartile range (IQR)) follow-up of 2 (0-5) years and a median (IQR) number of investigations per participant of 4 (2-6). One PDAC, two low-grade neuroendocrine tumours and 41 cystic lesions were identified, including 23 IPMN (22 branch-duct (BD)). The PDAC case occurred in the top 10% of risk, and the BD-IPMN cases were evenly distributed amongst risk categories: low (6/107), medium (10/107) and high (6/107) (P = 0.63). CONCLUSIONS: The risk of finding BD-IPMN was independent of genetic predisposition and so they should be managed according to guidelines for incidental finding of IPMN.


Assuntos
Carcinoma/epidemiologia , Predisposição Genética para Doença , Neoplasias Pancreáticas/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma/genética , Carcinoma/patologia , Estudos de Coortes , Detecção Precoce de Câncer , Europa (Continente)/epidemiologia , Família , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Linhagem , Sistema de Registros , Fatores de Risco , Adulto Jovem
13.
Gastric Cancer ; 22(3): 577-586, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30311042

RESUMO

AIM: The aim of this study was to determine prognostic factors in patients treated with second-line therapy (L2) for locally advanced or metastatic gastric and gastro-esophageal junction (GEJ) adenocarcinoma in a randomized phase III study with predefined L2. METHODS: In the FFCD-0307 study, patients were randomly assigned to receive in L1 either epirubicin, cisplatin, and capecitabine (ECX arm) or fluorouracil, leucovorin, and irinotecan (FOLFIRI arm). L2 treatment was predefined (FOLFIRI for the ECX arm and ECX for the FOLFIRI arm). Chi square tests were used to compare the characteristics of patients treated in L2 with those of patients who did not receive L2. Prognostic factors in L2 for progression-free survival (PFS) and overall survival (OS) were analyzed using a Cox model. RESULTS: Among 416 patients included, 101/209 (48.3%) patients in the ECX arm received FOLFIRI in L2, and 81/207 (39.1%) patients in the FOLFIRI arm received ECX in L2. Patients treated in L2, compared with those who only received L1 had : a better ECOG score (0-1: 90.4% versus 79.7%; p = 0.0002), more frequent GEJ localization (40.8% versus 27.6%; p = 0.005), and lower platelet count (median: 298000 versus 335000/mm3; p = 0.02). In multivariate analyses, age < 60 years at diagnosis (HR 1.49, 95% CI 1.09-2.03, p = 0.013) and ECOG score 2 before L2 (HR 2.62, 95% CI 1.41-4.84, p = 0.005) were the only significant poor prognostic factors for OS. CONCLUSION: Age ≥ 60 years at diagnosis and ECOG score 0/1 before L2 were the only favorable prognostic factors for OS.


Assuntos
Adenocarcinoma/secundário , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Junção Esofagogástrica/patologia , Neoplasias Gástricas/patologia , Adenocarcinoma/tratamento farmacológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Capecitabina/administração & dosagem , Cisplatino/administração & dosagem , Epirubicina/administração & dosagem , Junção Esofagogástrica/efeitos dos fármacos , Feminino , Fluoruracila/administração & dosagem , Seguimentos , Humanos , Irinotecano/administração & dosagem , Leucovorina/administração & dosagem , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Neoplasias Gástricas/tratamento farmacológico , Taxa de Sobrevida
14.
Ann Oncol ; 28(2): 339-343, 2017 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-27836885

RESUMO

BACKGROUND: In a phase III trial in patients with advanced, well-differentiated, progressive pancreatic neuroendocrine tumors, sunitinib 37.5 mg/day improved investigator-assessed progression-free survival (PFS) versus placebo (11.4 versus 5.5 months; HR, 0.42; P < 0.001). Here, we present PFS using retrospective blinded independent central review (BICR) and final median overall survival (OS), including an assessment highlighting the impact of patient crossover from placebo to sunitinib. PATIENTS AND METHODS: In this randomized, double-blind, placebo-controlled study, cross-sectional imaging from patients was evaluated retrospectively by blinded third-party radiologists using a two-reader, two-time-point lock, followed by a sequential locked-read, batch-mode paradigm. OS was summarized using the Kaplan-Meier method and Cox proportional hazards model. Crossover-adjusted OS effect was derived using rank-preserving structural failure time (RPSFT) analyses. RESULTS: Of 171 randomized patients (sunitinib, n = 86; placebo, n = 85), 160 (94%) had complete scan sets/time points. By BICR, median (95% confidence interval [CI]) PFS was 12.6 (11.1-20.6) months for sunitinib and 5.8 (3.8-7.2) months for placebo (HR, 0.32; 95% CI 0.18-0.55; P = 0.000015). Five years after study closure, median (95% CI) OS was 38.6 (25.6-56.4) months for sunitinib and 29.1 (16.4-36.8) months for placebo (HR, 0.73; 95% CI 0.50-1.06; P = 0.094), with 69% of placebo patients having crossed over to sunitinib. RPSFT analysis confirmed an OS benefit for sunitinib. CONCLUSIONS: BICR confirmed the doubling of PFS with sunitinib compared with placebo. Although the observed median OS improved by nearly 10 months, the effect estimate did not reach statistical significance, potentially due to crossover from placebo to sunitinib. TRIAL REGISTRATION NUMBER: NCT00428597.


Assuntos
Indóis/administração & dosagem , Tumores Neuroendócrinos/tratamento farmacológico , Neoplasias Pancreáticas/tratamento farmacológico , Pirróis/administração & dosagem , Antineoplásicos/administração & dosagem , Estudos Transversais , Intervalo Livre de Doença , Método Duplo-Cego , Humanos , Estimativa de Kaplan-Meier , Tumores Neuroendócrinos/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Modelos de Riscos Proporcionais , Sunitinibe , Taxa de Sobrevida
15.
Biophys J ; 110(9): 2044-52, 2016 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-27166812

RESUMO

Electron paramagnetic resonance (EPR), an established and powerful methodology for studying atomic-scale biomolecular structure and dynamics, typically requires in excess of 10(12) labeled biomolecules. Single-molecule measurements provide improved insights into heterogeneous behaviors that can be masked in ensemble measurements and are often essential for illuminating the molecular mechanisms behind the function of a biomolecule. Here, we report EPR measurements of a single labeled biomolecule. We selectively label an individual double-stranded DNA molecule with a single nanodiamond containing nitrogen-vacancy centers, and optically detect the paramagnetic resonance of nitrogen-vacancy spins in the nanodiamond probe. Analysis of the spectrum reveals that the nanodiamond probe has complete rotational freedom and that the characteristic timescale for reorientation of the nanodiamond probe is slow compared with the transverse spin relaxation time. This demonstration of EPR spectroscopy of a single nanodiamond-labeled DNA provides the foundation for the development of single-molecule magnetic resonance studies of complex biomolecular systems.


Assuntos
DNA/química , Nanodiamantes/química , Espectroscopia de Ressonância de Spin Eletrônica , Modelos Moleculares , Conformação Molecular
16.
Biomed Microdevices ; 18(2): 38, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27106026

RESUMO

EPR (electron paramagnetic resonance) based biological oximetry is a powerful tool that accurately and repeatedly measures tissue oxygen levels. In vivo determination of oxygen in tissues is crucial for the diagnosis and treatment of a number of diseases. Here, we report the first successful fabrication and remarkable properties of nanofiber sensors for EPR-oximetry applications. Lithium octa-n-butoxynaphthalocyanine (LiNc- BuO), an excellent paramagnetic oxygen sensor, was successfully encapsulated in 300-500 nm diameter fibers consisting of a core of polydimethylsiloxane (PDMS) and a shell of polycaprolactone (PCL) by electrospinning. This core-shell nanosensor (LiNc-BuO-PDMS-PCL) shows a linear dependence of linewidth versus oxygen partial pressure (pO2). The nanofiber sensors have response and recovery times of 0.35 s and 0.55 s, respectively, these response and recovery times are ~12 times and ~218 times faster than those previously reported for PDMS-LiNc-BuO chip sensors. This greater responsiveness is likely due to the high porosity and excellent oxygen permeability of the nanofibers. Electrospinning of the structurally flexible PDMS enabled the fabrication of fibers having tailored spin densities. Core-shell encapsulation ensures the non-exposure of embedded LiNc-BuO and mitigates potential biocompatibility concerns. In vitro evaluation of the fiber performed under exposure to cultured cells showed that it is both stable and biocompatible. The unique combination of biocompatibility due to the PCL 'shell,' the excellent oxygen transparency of the PDMS core, and the excellent oxygen-sensing properties of LiNc-BuO makes LiNc-BuO-PDMS-PCL platform promising for long-term oximetry and repetitive oxygen measurements in both biological systems and clinical applications.


Assuntos
Fenômenos Magnéticos , Nanofibras/química , Oximetria/instrumentação , Animais , Células CHO , Cricetinae , Cricetulus , Dimetilpolisiloxanos/química , Teste de Materiais , Oxigênio/análise , Poliésteres/química , Porfirinas/química , Pressão , Fatores de Tempo
17.
Nature ; 466(7308): 845-8, 2010 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-20703302

RESUMO

The discovery of new phenomena in layered and nanostructured magnetic devices is driving rapid growth in nanomagnetics research. Resulting applications such as giant magnetoresistive field sensors and spin torque devices are fuelling advances in information and communications technology, magnetoelectronic sensing and biomedicine. There is an urgent need for high-resolution magnetic-imaging tools capable of characterizing these complex, often buried, nanoscale structures. Conventional ferromagnetic resonance (FMR) provides quantitative information about ferromagnetic materials and interacting multicomponent magnetic structures with spectroscopic precision and can distinguish components of complex bulk samples through their distinctive spectroscopic features. However, it lacks the sensitivity to probe nanoscale volumes and has no imaging capabilities. Here we demonstrate FMR imaging through spin-wave localization. Although the strong interactions in a ferromagnet favour the excitation of extended collective modes, we show that the intense, spatially confined magnetic field of the micromagnetic probe tip used in FMR force microscopy can be used to localize the FMR mode immediately beneath the probe. We demonstrate FMR modes localized within volumes having 200 nm lateral dimensions, and improvements of the approach may allow these dimensions to be decreased to tens of nanometres. Our study shows that this approach is capable of providing the microscopic detail required for the characterization of ferromagnets used in fields ranging from spintronics to biomagnetism. This method is applicable to buried and surface magnets, and, being a resonance technique, measures local internal fields and other magnetic properties with spectroscopic precision.

18.
Nature ; 466(7309): 954-8, 2010 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-20725036

RESUMO

Ferroelectric ferromagnets are exceedingly rare, fundamentally interesting multiferroic materials that could give rise to new technologies in which the low power and high speed of field-effect electronics are combined with the permanence and routability of voltage-controlled ferromagnetism. Furthermore, the properties of the few compounds that simultaneously exhibit these phenomena are insignificant in comparison with those of useful ferroelectrics or ferromagnets: their spontaneous polarizations or magnetizations are smaller by a factor of 1,000 or more. The same holds for magnetic- or electric-field-induced multiferroics. Owing to the weak properties of single-phase multiferroics, composite and multilayer approaches involving strain-coupled piezoelectric and magnetostrictive components are the closest to application today. Recently, however, a new route to ferroelectric ferromagnets was proposed by which magnetically ordered insulators that are neither ferroelectric nor ferromagnetic are transformed into ferroelectric ferromagnets using a single control parameter, strain. The system targeted, EuTiO(3), was predicted to exhibit strong ferromagnetism (spontaneous magnetization, approximately 7 Bohr magnetons per Eu) and strong ferroelectricity (spontaneous polarization, approximately 10 microC cm(-2)) simultaneously under large biaxial compressive strain. These values are orders of magnitude higher than those of any known ferroelectric ferromagnet and rival the best materials that are solely ferroelectric or ferromagnetic. Hindered by the absence of an appropriate substrate to provide the desired compression we turned to tensile strain. Here we show both experimentally and theoretically the emergence of a multiferroic state under biaxial tension with the unexpected benefit that even lower strains are required, thereby allowing thicker high-quality crystalline films. This realization of a strong ferromagnetic ferroelectric points the way to high-temperature manifestations of this spin-lattice coupling mechanism. Our work demonstrates that a single experimental parameter, strain, simultaneously controls multiple order parameters and is a viable alternative tuning parameter to composition for creating multiferroics.


Assuntos
Eletricidade , Európio/química , Magnetismo , Óxidos/química , Titânio/química , Capacitância Elétrica , Microscopia Eletrônica de Transmissão e Varredura , Temperatura , Difração de Raios X
19.
Ann Oncol ; 26(6): 1194-1200, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25858497

RESUMO

BACKGROUND: Masitinib is a selective oral tyrosine-kinase inhibitor. The efficacy and safety of masitinib combined with gemcitabine was compared against single-agent gemcitabine in patients with advanced pancreatic ductal adenocarcinoma (PDAC). PATIENTS AND METHODS: Patients with inoperable, chemotherapy-naïve, PDAC were randomized (1 : 1) to receive gemcitabine (1000 mg/m(2)) in combination with either masitinib (9 mg/kg/day) or a placebo. The primary endpoint was overall survival (OS) in the modified intent-to-treat population. Secondary OS analyses aimed to characterize subgroups with poor survival while receiving single-agent gemcitabine with subsequent evaluation of masitinib therapeutic benefit. These prospectively declared subgroups were based on pharmacogenomic data or a baseline characteristic. RESULTS: Three hundred and fifty-three patients were randomly assigned to receive either masitinib plus gemcitabine (N = 175) or placebo plus gemcitabine (N = 178). Median OS was similar between treatment-arms for the overall population, at respectively, 7.7 and 7.1 months, with a hazard ratio (HR) of 0.89 (95% CI [0.70; 1.13]. Secondary analyses identified two subgroups having a significantly poor survival rate when receiving single-agent gemcitabine; one defined by an overexpression of acyl-CoA oxidase-1 (ACOX1) in blood, and another via a baseline pain intensity threshold (VAS > 20 mm). These subgroups represent a critical unmet medical need as evidenced from median OS of 5.5 months in patients receiving single-agent gemcitabine, and comprise an estimated 63% of patients. A significant treatment effect was observed in these subgroups for masitinib with median OS of 11.7 months in the 'ACOX1' subgroup [HR = 0.23 (0.10; 0.51), P = 0.001], and 8.0 months in the 'pain' subgroup [HR = 0.62 (0.43; 0.89), P = 0.012]. Despite an increased toxicity of the combination as compared with single-agent gemcitabine, side-effects remained manageable. CONCLUSIONS: The present data warrant initiation of a confirmatory study that may support the use of masitinib plus gemcitabine for treatment of PDAC patients with overexpression of ACOX1 or baseline pain (VAS > 20mm). Masitinib's effect in these subgroups is also supported by biological plausibility and evidence of internal clinical validation. TRIAL REGISTRATION: ClinicalTrials.gov:NCT00789633.


Assuntos
Antimetabólitos Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Ductal Pancreático/tratamento farmacológico , Desoxicitidina/análogos & derivados , Neoplasias Pancreáticas/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Tiazóis/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Antimetabólitos Antineoplásicos/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Benzamidas , Biomarcadores Tumorais/genética , Carcinoma Ductal Pancreático/enzimologia , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/mortalidade , Carcinoma Ductal Pancreático/patologia , Desoxicitidina/efeitos adversos , Desoxicitidina/uso terapêutico , Europa (Continente) , Feminino , Humanos , Análise de Intenção de Tratamento , Masculino , Pessoa de Meia-Idade , Oxirredutases/genética , Neoplasias Pancreáticas/enzimologia , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/mortalidade , Neoplasias Pancreáticas/patologia , Farmacogenética , Piperidinas , Medicina de Precisão , Valor Preditivo dos Testes , Modelos de Riscos Proporcionais , Estudos Prospectivos , Inibidores de Proteínas Quinases/efeitos adversos , Piridinas , Fatores de Risco , Tiazóis/efeitos adversos , Fatores de Tempo , Resultado do Tratamento , Estados Unidos , Gencitabina
20.
Phys Rev Lett ; 115(24): 246602, 2015 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-26705647

RESUMO

We present the measurement of ferromagnetic resonance (FMR-)driven spin pumping and three-terminal electrical spin injection within the same silicon-based device. Both effects manifest in a dc spin accumulation voltage V_{s} that is suppressed as an applied field is rotated to the out-of-plane direction, i.e., the oblique Hanle geometry. Comparison of V_{s} between these two spin injection mechanisms reveals an anomalously strong suppression of FMR-driven spin pumping with increasing out-of-plane field H_{app}^{z}. We propose that the presence of the large ac component to the spin current generated by the spin pumping approach, expected to exceed the dc value by 2 orders of magnitude, is the origin of this discrepancy through its influence on the spin dynamics at the oxide-silicon interface. This convolution, wherein the dynamics of both the injector and the interface play a significant role in the spin accumulation, represents a new regime for spin injection that is not well described by existing models of either FMR-driven spin pumping or electrical spin injection.

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