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1.
Int J Nanomedicine ; 15: 7979-7993, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33116513

RESUMO

Background: Both magnetic nanoparticles (MNPs) and exosomes derived from bone mesenchymal stem cells (BMSC-Exos) have been reported to improve wound healing. In this study, novel exosomes (mag-BMSC-Exos) would be fabricated from BMSCs with the stimulation of MNPs and a static magnetic field (SMF) to further enhance wound repair. Methods: Mag-BMSC-Exos, namely, exosomes derived from BMSCs preconditioned with Fe3O4 nanoparticles and a SMF, together with BMSC-Exos were both first isolated by ultracentrifugation, respectively. Afterwards, we conducted in vitro experiments, including scratch wound assays, transwell assays, and tube formation assays, and established an in vivo wound healing model. The miRNA expression profiles were compared between BMSC-Exos and mag-BMSC-Exos to detect the potential mechanism of improving wound healing. At last, the function of exosomal miR-21-5p during wound healing was confirmed by utilizing a series of gain- and loss-of-function experiments in vitro. Results: The optimal working magnetic condition was 50 µg/mL Fe3O4 nanoparticles combined with 100 mT SMF. In vitro, mag-BMSC-Exo administration promoted proliferation, migration and angiogenesis to a greater extent than BMSC-Exo administration. Local transplantation of mag-BMSC-Exos into rat skin wounds resulted in accelerated wound closure, narrower scar widths and enhanced angiogenesis compared with BMSC-Exo transplantation. Notably, miR-21-5p was found to be highly enriched in mag-BMSC-Exos and served as a critical mediator in mag-BMSC-Exo-induced regulatory effects through inhibition of SPRY2 and activation of the PI3K/AKT and ERK1/2 signaling pathways. Conclusion: Mag-BMSC-Exos can further enhance wound healing than BMSC-Exos by improving angiogenesis and fibroblast function, and miR-21-5p upregulation in mag-BMSC-Exos might be the potential mechanism. This work offers an effective and promising protocol to improve wound healing in clinic.


Assuntos
Exossomos/efeitos dos fármacos , Exossomos/metabolismo , Campos Magnéticos , Nanopartículas de Magnetita , Células-Tronco Mesenquimais/citologia , MicroRNAs/genética , Regulação para Cima , Cicatrização , Animais , Fibroblastos/citologia , Fibroblastos/metabolismo , Sistema de Sinalização das MAP Quinases , Proteínas do Tecido Nervoso/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Ratos
2.
PLoS One ; 15(10): e0238704, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33035214

RESUMO

The aim of this work was to use TOPAS Monte Carlo simulations to model the effect of magnetic fields on dose distributions in brachytherapy lung treatments, under ideal and clinical conditions. Idealistic studies were modeled consisting of either a monoenergetic electron source of 432 keV, or a polyenergetic electron source using the spectrum of secondary electrons produced by 192Ir gamma-ray irradiation. The electron source was positioned in the center of a homogeneous, lung tissue phantom (ρ = 0.26 g/cm3). Conversely, the clinical study was simulated using the VariSource VS2000 192Ir source in a patient with a lung tumor. Three contoured volumes were considered: the tumor, the planning tumor volume (PTV), and the lung. In all studies, dose distributions were calculated in the presence or absence of a constant magnetic field of 3T. Also, TG-43 parameters were calculated for the VariSource and compared with published data from EGS-brachy (EGSnrc) and PENELOPE. The magnetic field affected the dose distributions in the idealistic studies. For the monoenergetic and poly-energetic studies, the radial distance of the 10% iso-dose line was reduced in the presence of the magnetic field by 64.9% and 24.6%, respectively. For the clinical study, the magnetic field caused differences of 10% on average in the patient dose distributions. Nevertheless, differences in dose-volume histograms were below 2%. Finally, for TG-43 parameters, the dose-rate constant from TOPAS differed by 0.09% ± 0.33% and 0.18% ± 0.33% with respect to EGS-brachy and PENELOPE, respectively. The geometry and anisotropy functions differed within 1.2% ± 1.1%, and within 0.0% ± 0.3%, respectively. The Lorentz forces inside a 3T magnetic resonance machine during 192Ir brachytherapy treatment of the lung are not large enough to affect the tumor dose distributions significantly, as expected. Nevertheless, large local differences were found in the lung tissue. Applications of this effect are therefore limited by the fact that meaningful differences appeared only in regions containing air, which is not abundant inside the human.


Assuntos
Braquiterapia/métodos , Neoplasias Pulmonares/radioterapia , Pulmão/efeitos da radiação , Campos Magnéticos , Braquiterapia/estatística & dados numéricos , Simulação por Computador , Relação Dose-Resposta à Radiação , Elétrons , Humanos , Radioisótopos de Irídio/administração & dosagem , Radioisótopos de Irídio/farmacocinética , Radioisótopos de Irídio/uso terapêutico , Imagem por Ressonância Magnética , Método de Monte Carlo , Imagens de Fantasmas , Compostos Radiofarmacêuticos/administração & dosagem , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/uso terapêutico , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Distribuição Tecidual
3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4766-4769, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019056

RESUMO

In recent years, the Simultaneous Magnetic Actuation and Localization (SMAL) technology has been developed to accelerate and locate the wireless capsule endoscopy (WCE) in the intestine. In this paper, we propose a novel approach to detect the state of the capsule for improving the localization results. By creating a function to fit the relationship between the theoretical values of the actuating magnetic field and the measurement results, we present an algorithm for automatic estimation of the capsule state according to the fitting parameters. Experiment results on phantoms demonstrate the feasibility of the proposed method for detecting different states of the capsule during magnetic actuation.


Assuntos
Endoscopia por Cápsula , Algoritmos , Campos Magnéticos , Magnetismo
4.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1795-1798, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018347

RESUMO

This contribution deals with the detection and imaging of magnetic modulated nanoparticles by means of ultra-wideband sensing. We performed phantom measurements in a practical measurement setup where the magnetic nanoparticles are modulated by a static and a low periodic changing external magnetic field. We investigated the influence of the modulation type of the polarizing magnetic field on both, detectability and imaging of magnetic nanoparticles. We can conclude that both modulations generate a sufficient contrast in order that the nanoparticles were detected at the correct position in a three-dimensional volume. The imaging results, including 32 channels, indicate that the two state (ON/OFF) modulation of the magnetic field under constant environmental conditions shows better results compared to a sinusoidal excitation of the magnetic field.


Assuntos
Nanopartículas de Magnetita , Imageamento de Micro-Ondas , Campos Magnéticos , Magnetismo , Micro-Ondas
5.
Artigo em Inglês | MEDLINE | ID: mdl-33018484

RESUMO

In this study, we investigated the feasibility of computationally reconstructing the 3D geometry of the stomach by performing source localization of the magnetic field (MF) induced from the stomach surface. Anatomically realistic stomach and torso models of a human participant, reconstructed from the CT images, were used in the computations. First, 128 coils with a radius of 5 mm were positioned on different locations on the stomach model. Next, MF at the sensor positions were computed using Bio-Savart law for the currents of 10 and 100 mA. Then, three noise levels were defined using the biomagnetic data recorded from the same participant and two additional sets of generated white-noise resulting in mean signal to noise ratios (SNR) of 20 and 10 dB. Finally, for each combination of the current and noise level, the magnetic dipole (MDP) approximation was performed to estimate coil positions. The performance of the source localization was assessed by computing the goodness of fit (GOF) values and the distance between the coil and the estimated MDP positions. We obtained GOF values over 98% for all coils and a mean localization error of 0.69±0.08 mm was achieved when 100 mA current was used to induce MF and only biomagnetic data was added. When additional white-noise was added, the GOF values decreased to 95% and the mean localization error increased to around 4 mm. A current of 10 mA was enough to localize the coil positions with a mean error around 8 mm even for the highest noise level we tested but for the few coils furthest from the body surface, the error was around 10 cm. The results indicate that source localization using the MDP approximation can successfully extract spatial information of the stomach.Clinical relevance-Extracting the spatial information of the stomach during the recording of the slow wave activity provides new insights in assessing gastric recordings and relating to disorders.


Assuntos
Campos Magnéticos , Estômago , Humanos , Magnetismo , Estômago/diagnóstico por imagem , Tronco
6.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2512-2515, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018517

RESUMO

The routine diagnosis of gastric motility disorders represents a significant problem to current clinical practice. Magnetogastrography (MGG) provides a non-invasive option for assessing gastric slow wave (SW) dysrhythmias that are associated with motility disorders. However, its ability to characterize SW propagation is impaired by the limited spatial coverage of existing superconducting quantum interference devices (SQUIDs). Recently developed optically-pumped magnetometers can potentially substitute SQUIDs and enable subject-specific MGG arrays with greater spatial coverage. This study developed simulations of gastric MGG to determine the distribution of the magnetic fields (MFs) generated by SWs above the torso, and investigated the impact of several realistic dysrhythmic patterns of propagation. The distribution of MFs was found to vary significantly for different patterns of SW propagation, with ectopic dysrhythmia displaying the greatest difference from normal. Notably, some important proportion of the MFs lay outside the coverage of an existing experimental SQUID array used in gastrointestinal research for some simulated SW propagation patterns, such as retrograde activity. Results suggest that MGG measurements should be made over the entire frontal face of the torso to capture all of the strongest MFs generated by SWs.Clinical relevance- This provides a guide for the placement of MGG sensors for the capture of both normal and dysrhythmic gastric slow wave propagation.


Assuntos
Motilidade Gastrointestinal , Trato Gastrointestinal , Campos Magnéticos , Estômago/diagnóstico por imagem
7.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3415-3419, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018737

RESUMO

Magnetomyography (MMG) is the measurement of magnetic signals generated in the skeletal muscle of humans by electrical activities. However, current technologies developed to detect such tiny magnetic field are bulky, costly and require working at the temperature-controlled environment. Developing a miniaturized, low cost and room temperature magnetic sensors provide an avenue to enhance this research field. Herein, we present an integrated tunnelling magnetoresistive (TMR) array for room temperature MMG applications. TMR sensors were developed with low-noise analogue front-end circuitry to detect the MMG signals without and with averaging at a high signal-to-noise ratio. The MMG was achieved by averaging signals using the Electromyography (EMG) signal as a trigger. Amplitudes of 200 pT and 30 pT, corresponding to periods when the hand is tense and relaxed, were observed, which is consistent with muscle simulations based on finite-element method (FEM) considering the effect of distance from the observation point to the magnetic field source.


Assuntos
Campos Magnéticos , Músculo Esquelético , Eletromiografia , Humanos , Magnetismo , Razão Sinal-Ruído
8.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3537-3543, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018767

RESUMO

In this study, we present a temporal interference (TI) concept to achieve focal and steerable stimulation in the targeted brain area through transcranial magnetic stimulation (TMS). This method works by inducing two high-frequency electric fields with a slight frequency difference via two independent coils. The intrinsic nonlinear nature of the nerve membrane, which acts as a low-pass filter, does not allow the nerve to engage at high frequencies. Instead, neurons at the intersection of two electric fields can follow the frequency difference of the two fields. For 3D MRI-derived head models, the finite element method is used to compute the electric field induced by the time-varying magnetic field along with the electric field penetration depth and the activated volume for the specific coil parameters. A deeper stimulation with an acceptable spatial spread can be obtained by controlling the intersection of the fields by finding the optimal position and orientation of the two coils. Moreover, by changing the voltage ratio of the coils, and not their mechanical orientation, the intended area can be dynamically driven. The computational results show that the TI technique is an efficient approach to resolve the electric field depth-focality trade-off, which can be a reasonable alternative to complex coil designs. The system proposed in this paper shows a great promise for a more dynamic and focused magnetic stimulation.


Assuntos
Encéfalo , Estimulação Magnética Transcraniana , Eletricidade , Campos Eletromagnéticos , Campos Magnéticos
9.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3852-3855, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018841

RESUMO

This paper describes the design and testing of a compact, battery-powered repetitive Transcranial Magnetic Stimulation (rTMS) prototype. This device generates a 10 Hz magnetic pulse train with peak flux density of 100 mT at 2 cm distance. Circuit component design, including the inductor, switched LC resonator, and boost converter, are discussed in the context of weight and size reduction, and performance optimization. The experimental approach and rationale together with acquired results validating the rTMS prototype design are presented. To the best of our knowledge, this is the first comprehensive feasibility demonstration of an inexpensive, lightweight, and portable rTMS device able to generate therapeutic levels of current, pulse rise time, and number of pulses. The generated magnetic field was kept to 0.1 Tesla for safety and testing considerations, but nevertheless was very close to therapeutic intensity, with driving circuitry scalable to support much stronger fields.Clinical Relevance- This feasibility study of a compact, battery-powered rTMS prototype test platform aims to enable broader and more convenient rTMS treatment at home, in a small clinic, vessel, or field hospital, and potentially, on an ambulatory basis.


Assuntos
Fontes de Energia Elétrica , Estimulação Magnética Transcraniana , Frequência Cardíaca , Campos Magnéticos
10.
Mar Pollut Bull ; 159: 111489, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892922

RESUMO

A bacterial consortium immobilized in magnetic floating biochar gel beads is proposed to remove high-molecular-weight polycyclic aromatic hydrocarbons. The microbial consortium performed better than single strains and consisted of four strains of marine bacteria for degrading pyrene (PYR), two strains for benzo(a)pyrene (BAP), and three strains for indeno(1,2,3-cd)pyrene (INP), which were isolated from oil-contaminated seawater. The immobilized cells could biodegrade 89.8%, 66.9% and 78.2% of PYR, BAP and INP, respectively, and had better tolerance to pH, temperature and salinity than free cells. The Andrews model was used to explore the biodegradation kinetics, and when the initial concentrations of PYR, BAP, and INP were 7.80, 3.05, and 3.41 mg/L, the specific biodegradation rates reached maximum values of 0.2507, 0.1286, and 0.1930 d-1, respectively. The immobilized microbial consortium had a high HMW-PAH removal ability and good floatability and magnetic properties and could be collected by an external magnetic field.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Biodegradação Ambiental , Carvão Vegetal , Campos Magnéticos , Fenômenos Magnéticos , Consórcios Microbianos
11.
PLoS One ; 15(9): e0232808, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32941428

RESUMO

Studies on evoked responses in Parkinson's disease (PD) may be useful for elucidating the etiology and quantitative evaluation of PD. However, in previous studies, the association between evoked responses and detailed motor symptoms or cognitive functions has not been clear. This study investigated the characteristics of the visual (VEF), auditory (AEF), and somatosensory (SEF) evoked magnetic fields in patients with Parkinson's disease (PD), and the correlations between evoked fields and the patient's clinical characteristics, motor symptoms, and cognitive functions. Twenty patients with PD and 10 healthy controls (HCs) were recruited as participants. We recorded VEF, AEF, and SEF, collected clinical characteristics, performed physical examinations, and administered 10 cognitive tests. We investigated differences in the latencies of the evoked fields between patients with PD and HCs. We also evaluated the correlation of the latencies with motor symptoms and cognitive functioning. There were significant differences between the two groups in 6 of the cognitive tests, all of which suggested mild cognitive impairment in patients with PD. The latencies of the VEF N75m, P100m, N145m, AEF P50m, P100m, and SEF P60m components were greater in the patients with PD than in the HCs. The latencies mainly correlated with medication and motor symptoms, less so with cognitive tests, with some elements of the correlations remaining significant after Bonferroni correction. In conclusion, the latencies of the VEF, AEF, and SEF were greater in PD patients than in HCs and were mainly correlated with medication and motor symptoms rather than cognitive functioning. Findings from this study suggest that evoked fields may reflect basal ganglia functioning and are candidates for assessing motor symptoms or the therapeutic effects of medication in patients with PD.


Assuntos
Potenciais Evocados , Campos Magnéticos , Doença de Parkinson/fisiopatologia , Idoso , Cognição , Feminino , Humanos , Magnetoencefalografia , Masculino , Pessoa de Meia-Idade , Movimento , Doença de Parkinson/patologia , Tempo de Reação
12.
Sensors (Basel) ; 20(18)2020 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-32906831

RESUMO

Social distancing and contact/exposure tracing are accepted to be critical strategies in the fight against the COVID-19 epidemic. They are both closely connected to the ability to reliably establish the degree of proximity between people in real-world environments. We proposed, implemented, and evaluated a wearable proximity sensing system based on an oscillating magnetic field that overcomes many of the weaknesses of the current state of the art Bluetooth based proximity detection. In this paper, we first described the underlying physical principle, proposed a protocol for the identification and coordination of the transmitter (which is compatible with the current smartphone-based exposure tracing protocols). Subsequently, the system architecture and implementation were described, finally an elaborate characterization and evaluation of the performance (both in systematic lab experiments and in real-world settings) were performed. Our work demonstrated that the proposed system is much more reliable than the widely-used Bluetooth-based approach, particularly when it comes to distinguishing between distances above and below the 2.0 m threshold due to the magnetic field's physical properties.


Assuntos
Betacoronavirus , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/transmissão , Campos Magnéticos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Pneumonia Viral/transmissão , Dispositivos Eletrônicos Vestíveis , Busca de Comunicante , Infecções por Coronavirus/epidemiologia , Desenho de Equipamento , Humanos , Pneumonia Viral/epidemiologia , Smartphone , Distância Social , Dispositivos Eletrônicos Vestíveis/estatística & dados numéricos , Tecnologia sem Fio/instrumentação , Tecnologia sem Fio/estatística & dados numéricos
13.
Nat Commun ; 11(1): 4259, 2020 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-32848156

RESUMO

The plasma membrane is the interface through which cells interact with their environment. Membrane proteins are embedded in the lipid bilayer of the plasma membrane and their function in this context is often linked to their specific location and dynamics within the membrane. However, few methods are available to manipulate membrane protein location at the single-molecule level. Here, we use fluorescent magnetic nanoparticles (FMNPs) to track membrane molecules and to control their movement. FMNPs allow single-particle tracking (SPT) at 10 nm and 5 ms spatiotemporal resolution, and using a magnetic needle, we pull membrane components laterally with femtonewton-range forces. In this way, we drag membrane proteins over the surface of living cells. Doing so, we detect barriers which we could localize to the submembrane actin cytoskeleton by super-resolution microscopy. We present here a versatile approach to probe membrane processes in live cells via the magnetic control of membrane protein motion.


Assuntos
Nanopartículas de Magnetita , Proteínas de Membrana/metabolismo , Citoesqueleto de Actina/metabolismo , Animais , Linhagem Celular , Chlorocebus aethiops , Proteínas de Fluorescência Verde/metabolismo , Campos Magnéticos , Lipídeos de Membrana/metabolismo , Microscopia de Fluorescência , Nanotecnologia , Imagem Individual de Molécula/métodos
14.
PLoS One ; 15(7): e0236884, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32735614

RESUMO

OBJECTIVE: The definition of an in vivo nodal anatomical baseline is crucial for validation of representative lymph node dissections and accompanying pathology reports of pelvic cancers, as well as for assessing a potential therapeutic effect of extended lymph node dissections. Therefore the number, size and distribution of lymph nodes in the pelvis were assessed with high-resolution, large field-of-view, 7 Tesla (T) magnetic resonance imaging (MRI) with frequency-selective excitation. MATERIALS AND METHODS: We used 7 T MRI for homogeneous pelvic imaging in 11 young healthy volunteers. Frequency-selective imaging of water and lipids was performed to detect nodal structures in the pelvis. Number and size of detected nodes was measured and size distribution per region was assessed. An average volunteer-normalized nodal size distribution was determined. RESULTS: In total, 564 lymph nodes were detected in six pelvic regions. Mean number was 51.3 with a wide range of 19-91 lymph nodes per volunteer. Mean diameter was 2.3 mm with a range of 1 to 7 mm. 69% Was 2 mm or smaller. The overall size distribution was very similar to the average volunteer-normalized nodal size distribution. CONCLUSIONS: The amount of in vivo visible lymph nodes varies largely between subjects, whereas the normalized size distribution of nodes does not. The presence of many small lymph nodes (≤2mm) renders representative or complete removal of pelvic lymph nodes to be very difficult. 7T MRI may shift the in vivo detection limits of lymph node metastases in the future.


Assuntos
Linfonodos , Imagem por Ressonância Magnética/métodos , Adulto , Feminino , Humanos , Linfonodos/anatomia & histologia , Linfonodos/diagnóstico por imagem , Campos Magnéticos , Masculino , Pessoa de Meia-Idade , Pelve/diagnóstico por imagem
15.
PLoS One ; 15(8): e0237029, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764793

RESUMO

Paleomagnetic analysis of archaeological materials is crucial for understanding the behavior of the geomagnetic field in the past. As it is often difficult to accurately date the acquisition of magnetic information recorded in archaeological materials, large age uncertainties and discrepancies are common in archaeomagnetic datasets, limiting the ability to use these data for geomagnetic modeling and archaeomagnetic dating. Here we present an accurately dated reconstruction of the intensity and direction of the field in Jerusalem in August, 586 BCE, the date of the city's destruction by fire by the Babylonian army, which marks the end of the Iron Age in the Levant. We analyzed 54 floor segments, of unprecedented construction quality, unearthed within a large monumental structure that had served as an elite or public building and collapsed during the conflagration. From the reconstructed paleomagnetic directions, we conclude that the tilted floor segments had originally been part of the floor of the second story of the building and cooled after they had collapsed. This firmly connects the time of the magnetic acquisition to the date of the destruction. The relatively high field intensity, corresponding to virtual axial dipole moment (VADM) of 148.9 ± 3.9 ZAm2, accompanied by a geocentric axial dipole (GAD) inclination and a positive declination of 8.3°, suggests instability of the field during the 6th century BCE and redefines the duration of the Levantine Iron Age Anomaly. The narrow dating of the geomagnetic reconstruction enabled us to constrain the age of other Iron Age finds and resolve a long archaeological and historical discussion regarding the role and dating of royal Judean stamped jar handles. This demonstrates how archaeomagnetic data derived from historically-dated destructions can serve as an anchor for archaeomagnetic dating and its particular potency for periods in which radiocarbon is not adequate for high resolution dating.


Assuntos
Arqueologia/métodos , Planeta Terra , Campos Magnéticos , Materiais de Construção/análise , Materiais de Construção/história , Fogo/história , Pisos e Cobertura de Pisos/história , História Antiga , Humanos , Israel , Colapso Estrutural/história , Fatores de Tempo , Guerra/história
16.
Int J Nanomedicine ; 15: 5645-5659, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32848391

RESUMO

Introduction: Mesenchymal stem cells (MSCs) are a promising resource for tissue regeneration and repair. However, their clinical application is hindered by technical limitations related to MSC enrichment at the target sites. Methods: MSCs were labeled with magnetic Fe3O4 nanoparticles (NPs). We analyzed the effects of NP on cell proliferation, stem cell characteristics, and cytokine secretion. Furthermore, we induced NP-labeled MSC migration with an external magnetic field toward laser-induced skin wounds in rats and evaluated the associated anti-inflammatory effects. Results: Fe3O4 NP application did not adversely affect MSC characteristics. Moreover, Fe3O4 NP-labeled MSCs presented increased anti-inflammatory cytokine and chemokine production compared with unlabeled MSCs. Furthermore, MSCs accumulated at the injury site and magnetic targeting promoted NP-labeled MSC migration toward burn injury sites in vivo. On day 7 following MSC injection, reduced inflammation and promoted angiogenesis were observed in the magnetically targeted MSC group. In addition, anti-inflammatory factors were upregulated, whereas pro-inflammatory factors were downregulated within the magnetically targeted MSC group compared with those in the PBS group. Conclusion: This study demonstrates that magnetically targeted MSCs contribute to cell migration to the site of skin injury, improve anti-inflammatory effects and enhance angiogenesis compared with MSC injection alone. Therefore, magnetically targeted MSC therapy may be an effective treatment approach for epithelial tissue injuries.


Assuntos
Queimaduras/terapia , Lasers/efeitos adversos , Nanopartículas de Magnetita/química , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/química , Animais , Queimaduras/etiologia , Queimaduras/patologia , Movimento Celular , Proliferação de Células , Citocinas/metabolismo , Campos Magnéticos , Nanopartículas de Magnetita/uso terapêutico , Masculino , Ratos Wistar , Pele/patologia , Cicatrização
17.
Bioresour Technol ; 315: 123880, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32717519

RESUMO

This study aimed to investigate the influence of different intensities (15, 30 and 60 mT) and exposure times (1 h d-1, 24 h d-1) of magnetic fields (MF) on the stimulation of lipid synthesis by the microalga Chlorella homosphaera. The growth and biochemical characterization of protein, carbohydrate and lipid content were determined. Biomass concentration increased by 20.6% (30 mT, 1 h d-1) and 12.4% (60 mT, 1 h d-1) in the presence of MF. However, biomass decreased by 33.0% (15 mT, 1 h d-1) in relation to control cultivation (CC). The stress caused by the MF application stimulated lipid synthesis and biomass production. In all evaluated conditions, MF application showed a positive effect on lipid production; the application of 60 mT or 30 mT for 1 h d-1 increased lipid productivity by 108.4% and 135.1%, respectively. MF application with ferrite magnets was thus efficient to stimulate lipid synthesis.


Assuntos
Chlorella , Microalgas , Biocombustíveis , Biomassa , Clorofíceas , Lipídeos , Campos Magnéticos
18.
Mar Environ Res ; 159: 104958, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32662447

RESUMO

The goal of clean renewable energy production has promoted the large-scale deployment of marine renewable energy devices, and their associated submarine cable network. Power cables produce both electric and magnetic fields that raise environmental concerns as many marine organisms have magneto and electroreception abilities used for vital purposes. Magnetic and electric fields' intensities decrease with distance away from the cable. Accordingly, the benthic and the sedimentary compartments are exposed to the highest field values. Although marine invertebrate species are the major fauna of these potentially exposed areas, they have so far received little attention. We provide extensive background knowledge on natural and anthropogenic marine sources of magnetic and electric fields. We then compile evidence for magneto- and electro-sensitivity in marine invertebrates and further highlight what is currently known about their interactions with artificial sources of magnetic and electric fields. Finally we discuss the main gaps and future challenges that require further investigation.


Assuntos
Invertebrados , Campos Magnéticos , Navios , Animais , Organismos Aquáticos , Energia Renovável
19.
Nat Commun ; 11(1): 3637, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32686685

RESUMO

We report a strategy to boost Fenton reaction triggered by an exogenous circularly polarized magnetic field (MF) to enhance ferroptosis-like cell-death mediated immune response, as well as endow a responsive MRI capability by using a hybrid core-shell vesicles (HCSVs). HCSVs are prepared by loading ascorbic acid (AA) in the core and poly(lactic-co-glycolic acid) shell incorporating iron oxide nanocubes (IONCs). MF triggers the release of AA, resulting in the increase of ferrous ions through the redox reaction between AA and IONCs. A significant tumor suppression is achieved by Fenton reaction-mediated ferroptosis-like cell-death. The oxidative stress induced by the Fenton reaction leads to the exposure of calreticulin on tumor cells, which leads to dendritic cells maturation and the infiltration of cytotoxic T lymphocytes in tumor. Furthermore, the depletion of ferric ions during treatment enables monitoring of the Fe reaction in MRI-R2* signal change. This strategy provides a perspective on ferroptosis-based immunotherapy.


Assuntos
Ferroptose/efeitos dos fármacos , Campos Magnéticos , Nanopartículas de Magnetita , Neoplasias/terapia , Animais , Ácido Ascórbico/farmacologia , Calreticulina/metabolismo , Linhagem Celular Tumoral , Sistemas de Liberação de Medicamentos/métodos , Compostos Férricos/química , Imunoterapia/métodos , Imagem por Ressonância Magnética , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/uso terapêutico , Camundongos , Nanomedicina/métodos , Nanopartículas/química , Nanopartículas/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/imunologia , Estresse Oxidativo , Linfócitos T Citotóxicos/metabolismo
20.
PLoS One ; 15(7): e0236121, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32697813

RESUMO

This paper presents the derivation and experimental validation of algorithms for modeling and estimation of soft continuum manipulators using Lie group variational integration. Existing approaches are generally limited to static and quasi-static analyses, and are not sufficiently validated for dynamic motion. However, in several applications, models need to consider the dynamical behavior of the continuum manipulators. The proposed modeling and estimation formulation is obtained from a discrete variational principle, and therefore grants outstanding conservation properties to the continuum mechanical model. The main contribution of this article is the experimental validation of the dynamic model of soft continuum manipulators, including external torques and forces (e.g., generated by magnetic fields, friction, and the gravity), by carrying out different experiments with metal rods and polymer-based soft rods. To consider dissipative forces in the validation process, distributed estimation filters are proposed. The experimental and numerical tests also illustrate the algorithm's performance on a magnetically-actuated soft continuum manipulator. The model demonstrates good agreement with dynamic experiments in estimating the tip position of a Polydimethylsiloxane (PDMS) rod. The experimental results show an average absolute error and maximum error in tip position estimation of 0.13 mm and 0.58 mm, respectively, for a manipulator length of 60.55 mm.


Assuntos
Algoritmos , Simulação por Computador , Modelos Teóricos , Polímeros/química , Robótica , Campos Magnéticos
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