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BACKGROUND:Magnetically responsive hydrogels have great advantages in bone tissue engineering,which is more conducive to the minimally invasive and efficient promotion of osteogenesis. OBJECTIVE:To review the application advances of magnetically responsive hydrogels in bone tissue engineering. METHODS:PubMed,Web of Science,WanFang and CNKI databases were used to search relevant literature.The English search terms were"Magnetic Hydrogels,Magnetic Nanoparticles,Superparamagnetic Nanoparticles,Fe3O4,SPIONs,Magnetic Fields,Bone Regeneration,Bone Repair,Bone Tissue Engineering".The Chinese search terms were"Magnetic Hydrogel,Magnetic Nanoparticles,Superparamagnetic Iron Oxide Nanoparticles,Magnetic Field,Iron Oxide Nanoparticles,Bone Regeneration,Bone Reconstruction,Bone Repair,Bone Tissue Engineering".After preliminary screening of all articles according to the inclusion and exclusion criteria,60 articles were finally retained for review. RESULTS AND CONCLUSION:(1)In recent years,due to the emergence of magnetic nanoparticles,more and more magnetic responsive scaffold materials have been developed.Among them,magnetic responsive hydrogels containing iron oxide nanoparticles and superparamagnetic iron oxide nanoparticles have outstanding mechanical properties and good biocompatibility.It can quickly respond to the external magnetic field and provide the magnetic-mechanical signals needed for seed cells to form bone.(2)Magnetic-responsive hydrogel can be used as a carrier to accurately regulate the release time of growth factors.(3)Under the three-dimensional microenvironment culture platform based on magnetically responsive hydrogel,the magnetic force at the interface between the magnetic response hydrogel and cells can activate cell surface sensitive receptors,enhance cell activity,and promote the integration of new bone and host bone.(4)The injectable magnetically responsive hydrogel can be used in the field of magnetic hyperthermia and biological imaging of bone tumors.(5)At present,magnetically responsive hydrogels are expected to mimic the anisotropic layered structure observed in natural bone tissue.However,most of the studies on magnetically responsive hydrogels focus on in vitro studies,and the mechanism of interaction between magnetically responsive hydrogels and the local microenvironment in vivo is still insufficient.(6)Therefore,based on the successful application of magnetic nanoparticles in magnetic resonance imaging,it is expected to optimize the properties of magnetic nanoparticles in the future to construct magnetic responsive hydrogels with suitable degradation properties,mechanical properties,and vascular functionalization,which can monitor changes in vivo in real time.
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BACKGROUND:Muscle weakness is a common symptom after coronavirus disease 2019(COVID-19)infection and affects the ability to perform daily activities in humans during recovery.Low-frequency pulsed magnetic field stimulation at a strength of 1.5 mT and a frequency of 3 300 Hz can enhance the maximal voluntary contraction and strength endurance of human skeletal muscle by inducing and activating classical transient receptor potential channel 1(TRPC1),which produces a series of pathological support effects on muscle tissue.It has not been studied whether this means will improve muscle weakness in patients recovering from COVID-19. OBJECTIVE:To select the low-frequency pulsed magnetic field for magnetic stimulation of lower limb muscle groups in patients with COVID-19,in order to observe the effect of this stimulation on the improvement of muscle weakness of lower limb muscle groups in patients with COVID-19 during the recovery period. METHODS:Fourteen patients infected with COVID-19(Omicron strain)positive for Innovita COVID-19 Ab Test(Colloidal Gold)and accompanied by muscle weakness were recruited and randomly divided into two groups:a test group receiving magnetic field stimulation and a control group receiving sham treatment,respectively.The total duration of the trial was 3 weeks.The test group was given low-frequency pulsed magnetic stimulation of the lower limbs every 48 hours and the control group was given the same intervention procedure as the test group but with sham stimulation.Patients in both groups were not informed whether the magnetic stimulation apparatus was running or not.Nine sessions were performed in both groups and the changes in the maximum voluntary contraction,explosive leg force and strength endurance of the local muscle groups of the lower limbs were subsequently observed in both groups. RESULTS AND CONCLUSION:Among the eight local muscle groups collected,seven local muscle groups in the test group showed an increase in the maximum voluntary contraction value after 3 weeks of low-frequency pulsed magnetic field stimulation.In the control group,there were only three muscle groups with improvement in the maximum voluntary contraction.The rate of improvement in the anterior and posterior muscle groups of the left leg in the test group was significantly higher than that in the control group.The longitudinal jump height and peak angular velocity of the knee joint in both groups were improved compared with the pre-test measurement,and the elevation rate of jumping height in the test group was higher than that in the control group.Under the fatigue condition,the decline rates of peak angular velocity of the knee joint and jumping height in the test group decreased significantly,while those in the control group did not change significantly.The above data confirmed that the low-frequency pulsed magnetic field stimulation with the intensity of 1.5 mT and frequency of 3 300 Hz could improve the muscle strength of more local muscle groups in the lower limbs of patients with COVID-19 during the recovery period compared with the human self-healing process,and the whole-body coordination ability and functional status based on explosive leg force of the legs could be significantly improved.Therefore,low-frequency pulsed magnetic field stimulation can be used as an effective,non-exercise rehabilitation tool to improve muscle weakness in the lower limbs of patients with COVID-19.
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Effect of pre-sowing magnetic field (MF) and electric current treatments on germination, seedling parameters and yield attributes in Buckwheat (Fagopyrum esculentum L) was investigated in this experiment. This study was designed to check the response of magnetic and electric treatments with different intensities and durations on buckwheat on different growth, yield and seedling parameters such as field emergence, leaf surface area, plant height, days to first flowering, seed yield per plant, biological yield, harvest index, germination per-cent, root length, shoot length, seedling fresh weight, seedling dry weight, vigour index ?, seed metabolic efficiency and chlorophyll content (a & b). Seeds of Buckwheat (IC-329456) treated by using an AC magnetic flux intensities 75mT, 100mT, 125mT for 3 and 5 minutes in the magnetic field and AC electric current ranging from 75mA, 100mA, 125mA for 30,60,90 seconds. In this study, it found that among various treatments T6 (Magnetic field @ 125mT for 5 minutes) performing better in terms of field emergence (96.04%), leaf area (30.87m2), days to first flowering(46days), seed yield per plant (8.80g), while lowest was found in control. Results showed that the seeds treated with magnetic field demonstrated remarkable effects on growth and yield parameters of buckwheat. Germination per-cent (99%), seedling fresh weight (0.177g), seedling dry weight (0.035) and chlorophyll (a & b) content was maximum in T6 (Magnetic field @ 125mT for 5 minutes) which performed better among the other treatments. Effect of treatments on seedling parameters were found to be non-significant. Both the electric current and magnetic field treatment of seeds is likely to play an important role in production of food which is free from toxic and chemical residues were beneficial for human consumption.
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Objective To investigate tumor cell killing effect of superparamagnetic Fe3O4 nanoparticles with cubic phase through magneto-mechanical force under a low-frequency vibrating magnetic field ( VMF). Methods A kind of strong magnetic and irregular-shaped Fe3O4 nanoparticles with cubic phase was synthesized by coprecipitation method. The Fe3O4 nanoparticles were exposed to a self-developed VMF and cell killing efficiency of the Fe3O4-mediated magneto-mechanical force was investigated. Results VMF alone had no effects on cell viability. After Fe3O4 nanoparticles were added, the cell viability significantly decreased with prolonging the VMF treatment time and increasing the Fe3O4 nanoparticle concentration. Lactate dehydrogenase released by damaged cells also increased with prolonging the VMF exposure time. Conclusions The irregular-shaped Fe3O4 nanoparticles can transfer magneto-mechanical force to tumor cells under VMF, cause structural damage of cells and result in cell death. The VMF generator developed in this study has simple structure and it is safe for use and convenient for operation. The developed magnetic nanoparticles and the corresponding cancer cell killing technique have the potential for clinical transformation.
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Objective:To study the influence of intensive magnet fields on radiation dose measurement, and to demonstrate the feasibility of measuring magnet field correction factor by a combination of medical linac with variable magnet fields in view of needing for accurate measurement of the doses from reference beam arising in MR image-guided radiotherapy.Methods:A photon radiation field and a variable field with 6 MV nominal high voltage were produced by using conventional medical electron linear accelerator equipped with a pair of electromagnets with magnetic field strength up to 1.5 T. Both PTW30013 and PTW31010 ionization chambers were used to test the responses of ionization chambers under different magnetic field strengths at four orientations in which the angles between ionization chamber axis and magnetic field direction were 0°, 180°, 90° and 270°, respectively. The magnetic factors, kB, M was calculated and compared with the reported values in literature. Results:The response of ionization chamber was proportional to the magnetic field strength before it reached to a peak around 1 T, and then fell down as the magnetic field continued to rise. When the magnetic field was 0.35 T, the magnetic factors of PTW31010 were 0.988 2±0.000 3 and 0.997 4±0.000 4 corresponding to 90° and 0° directions, the discrepancy between 0° scenario and literature was 0.05% ± 0.04%. When the magnetic field reached 1.5 T, the magnetic factor of PTW30013 was 0.958 9±0.000 5 at the situation of 90°, which was 0.60% ± 0.05% different from the literature value.Conclusions:Conventional 6 MV medical accelerator equipped with electromagnet can be used to measure the magnetic field factor of reference dosimetry for MRIgRT.
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Magnetic nanoparticles (MNP) have been widely used as biomaterials due to their unique magnetic responsiveness and biocompatibility, which also can promote osteogenic differentiation through their inherent micro-magnetic field. The MNP composite scaffold retains its superparamagnetism, which has good physical, mechanical and biological properties with significant osteogenic effects and . Magnetic field has been proved to promote bone tissue repair by affecting cell metabolic behavior. MNP composite scaffolds under magnetic field can synergically promote bone tissue repair and regeneration, which has great application potential in the field of bone tissue engineering. This article summarizes the performance of magnetic composite scaffold, the research progress on the effect of MNP composite scaffold with magnetic fields on osteogenesis, to provide reference for further research and clinical application.
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Cell Differentiation , Magnetite Nanoparticles , Osteogenesis , Tissue Engineering , Tissue ScaffoldsABSTRACT
Objective:To evaluate the effects of orthogonal magnetic fields on the dose distribution of 6 MeV X-ray in a uniform water and heterogeneous phantoms.Methods:The Monte Carlo simulation software Gate v8.2 was used to investigate the dose distribution of X-ray beams of different field sizes in a uniform water phantom, water-air/bone-water layer phantom and" custom lung model" in the magnetic field strength of 0.0, 0.5, 1.0, 1.5, 3.0 T, respectively. The relationship between the intensity of magnetic field and the dose distribution of X-rays in the phantoms was analyzed.Results:The existence of a magnetic field would cause the X-ray to shorten the built-up area in the water phantom; when the field was 10 cm×10 cm, the maximum dose on the central axis could change by up to 56.22%(3.0 T). The transverse dose distribution of the radiation field in the direction of the vertical magnetic field shifted to one side by up to 43.64%(-44.55%). The average dose of the air layer in the water-air-water phantom could be reduced by 57.4%(3.0 T). In the water-bone-water phantom, the dose at the proximal end of the bone layer was decreased by 16.5%, whereas the dose at the distal end was increased by 22.6%(1.5 T). The dose change in each layer in the customed lung model was positively correlated with the magnetic field strength.Conclusion:The existence of the orthogonal magnetic field will cause the change of X-ray dose distribution on the built-up area and both sides of the radiation field in the phantoms, which is more obvious adjacent to the interface of heterogeneous phantom.
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Objective:To study the method of intravascular angiography in vivo, analyze the clinical significance, and supply the basis of diagnosis and treatment of related orthopaedic diseases.Methods:The development was realized by improving the developer to increase the local concentration. Based on the study of Lijianmin-Chengkun Complexes and using the theory of magnetic microspheres, Fe 3O 4 magnetic microspheres with amino (negatively charged) shell are used to adsorb the aggregated ionic developer meglumine diatrizoate (positively charged diatrizoate). That is, by improving the method of developer, the magnetic microspheres can carry the developer to make new nanoparticles magnetic imaging composite particles. Under the action of external magnetic field, the magnetic imaging composite particles brought by blood circulation continue to stay and gather in the blood vessels in the magnetic field area, and the developer carried by the magnetic microspheres in the blood vessels in the magnetic field area is concentrated to reach the imaging concentration, so as to realize in vivo intravascular vascular imaging. By adjusting the ratio of the two reagents, the charge can be neutralized and condensed into small groups to improve the development efficiency. Thus, the electron microscope experiment, CT in vivo experiment, rabbit imaging experiment, experimental rabbit tissue picture confirmation, CT in vivo human body (the author is a volunteer) imaging experiment were carried out step by step. Results:Electron microscope experiment: meglumine diatrizoate, scanning electron microscope, the particle diameter is about 20 nm. Scanning electron microscope showed that the diameter of the magnetic microspheres was about 100 nm and the distribution was uniform. After the two reagents are mixed in a certain proportion, the neutralizing charge condenses into small groups, but it still has magnetohydrodynamic properties and strong paramagnetism. In vivo rabbit imaging experiment: the ideal intraosseous vascular imaging of the proximal tibia was captured. The tissue pictures of experimental rabbits confirmed that the distribution of Fe 3O 4 was obviously visible in the blood vessels in the proximal tibia on the side with magnetic field, but not on the side without magnetic field. In vivo human imaging experiment: the ideal intraosseous vascular imaging of the proximal fibula was captured. Conclusion:Through the preparation of new reagent of magnetic imaging composite particles (magnetic microspheres + meglumine diatrizoate), the concentration of in vivo bone developer can be achieved under the action of external magnetic field, and the in vivo external diameter ≥ 0.5mm can be achieved under CT thin-layer scanning.
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Objective:Effects of pole-specific acupuncture combined with Bobath on upper limb function, daily life ability and nerve function after traumatic brain injury were observed.Methods:A total of 142 patients with cerebral hemiplegia after traumatic brain injury from January 2019 to December 2020, were divided into the Bobath group (47 cases), the pole-specific acupuncture group (47 cases) and combination group (48 cases) by the random number method. Bobath group received Bobath rehabilitation, the pole-specific acupuncture group received pole-specific acupuncture rehabilitation, and combination group was given pole-specific acupuncture rehabilitation and Bobath treatment. The overall rehabilitation efficiency, limb function Fugl-Meyer scale score, Barthel index of daily life ability, nerve function, and other indicators were observed and compared.Results:After treatment, the overall recovery efficiency (86.96%) in combination group was significantly higher than that of the Bobath group (65.96%) and acupuncture group (64.44%)( χ2=5.84, P=0.016). After treatment, the limb function Fugl-Meyer scale (including upper limb and lower limb function scores)( F=19.38, 24.83, all Ps<0.01), daily life ability Barthel index (including cognitive ability situation score, language ability score, self-care ability score, social adaptability score and total score) of combination group were significantly higher than those in the Bobath group and acupuncture group ( F=14.91, 15.87, 18.71, 18.88, 32.62, all Ps<0.001), while the NIHSS score of combination group was significantly lower than that of the Bobath group and acupuncture group ( F=31.71, P<0.01). After treatment, the NE[(58.29±9.82)μg/L vs. (86.29±12.35)μg/L, (88.34±12.87)μg/L, F=33.39], DA[(204.29±20.26)μg/L vs. (278.72±27.56)μg/L, (281.14±27.82)μg/L, F=55.50], 5-HT[(231.27±20.12)μg/L vs. (294.74±29.34)μg/L, (298.19±28.73)μg/L, F=13.86], E[(21.85±3.19)μg/L vs. (28.37±4.07)μg/L, (28.26±4.14)μg/L, F=9.34] of combination group were significantly lower than those in the Bobath group and acupuncture group ( P<0.01). Conclusion:Magnetic pole-specific acupuncture combined with Bobath can improve the function of limbs, daily quality of life and nerve function of the patients with traumatic craniocerebral injury with cerebral palsy.
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ABSTRACT Background: Brazil has a top position regarding scientific production on noninvasive neuromodulation worldwide. Knowledge of scientometric phenomena involving Brazilian researchers who produce science on this theme may aid confidence in Brazilian clinical and research professionals. Objective: To investigate the scenario of research on the theme of noninvasive neuromodulation in Brazil. Methods: This was a scientometric study for mapping scientific production on this subject involving network phenomena, the professions of researchers, institutional affiliation, main research unit, total number of scientific articles on noninvasive neuromodulation published in journals, research sub-area and year of obtaining the PhD title. Public data from Lattes Platform curricula vitae and from VOSViewer© were used. Results: A total of 54 Brazilian researchers were identified, of whom 16 are research productivity fellows. Most of them are linked to institutions in southeastern Brazil, involving the professions of biology, biochemistry, physical education, physiotherapy, speech therapy, gerontology, medicine and psychology, with 1175 articles published in journals. These studies involve experimental animal and human models to account for mechanisms, observational studies, case reports, randomized clinical trials, systematic reviews, meta-analyses, product and process development, computer modeling and guidelines. Conclusions: Brazil occupies a prominent place in the world scenario of research on noninvasive neuromodulation, which is used by different professions for treatment of brain dysfunctions, with a trend towards expansion to other fields.
RESUMO Antecedentes: O Brasil ocupa posição de destaque na produção científica de neuromodulação não invasiva no mundo. O conhecimento dos fenômenos cientométricos envolvendo pesquisadores brasileiros que produzem ciência neste tema pode auxiliar na confiança dos profissionais clínicos e pesquisadores brasileiros. Objetivo: Investigar o cenário das pesquisas sobre a temática da neuromodulação não invasiva no Brasil. Métodos: Estudo cienciométrico para mapeamento da produção científica sobre o tema envolvendo fenômenos de rede, profissão dos pesquisadores, afiliação à instituição, unidade principal de pesquisa, número total de artigos científicos publicados em periódicos sobre neuromodulação não invasiva, subárea de pesquisa e ano de obtenção do título de doutor. Utilizou-se dados públicos dos currículos da Plataforma Lattes e do sistema VOSViewer©. Resultados: Foram identificados 54 pesquisadores brasileiros, dos quais 16 são bolsistas de produtividade em pesquisa, a maioria deles vinculados a instituições do Sudeste do Brasil, envolvendo as profissões de Biologia, Bioquímica, Educação Física, Fisioterapia, Fonoaudiologia, Gerontologia, Medicina e Psicologia, com 1175 artigos publicados em periódicos. As pesquisas envolvem modelos experimentais animais e humanos para estudar dos mecanismos, estudos observacionais, relatos de casos, ensaios clínicos randomizados, revisões sistemáticas, meta-análises, desenvolvimento de produtos e processos, modelagem computacional e diretrizes. Conclusões: O Brasil ocupa lugar de destaque no cenário mundial das pesquisas em neuromodulação não invasiva, sendo utilizado por diferentes profissões para o tratamento de disfunções cerebrais, que tendem a se expandir para outros campos.
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Humans , Animals , Biomedical Research , Publications , Research Personnel , Brain , BrazilABSTRACT
SUMMARY OBJECTIVE: The aim of this study was to compare the effect of transcutaneous electrical nerve stimulation (TENS), ultrasound (US), and pulsed electromagnetic field (PEMF) combination with TENS and US therapy alone in patients with supraspinatus tear. METHODS: Forty patients were included in this study. The patients were randomly divided into two groups as follows: PEMF (n=20) and Sham (n=20) groups. PEMF was applied to the first group at a frequency of 50 Hz, 25 G intensity, and 20 min/session. The device was turned off while PEMF was applied to the second group. Diathermy (US) and electrotherapy (TENS) were applied to both groups for 10 sessions. Numerical Rating Scale (NRS), University of California-Los Angeles (UCLA) Shoulder Scale, and Shoulder Pain and Disability Index (SPADI) were used as outcome measures. RESULTS: In both groups, there was a significant improvement in the NRS, UCLA Shoulder Scale, and SPADI scores after treatment compared with pretreatment (p<0.05). In the comparison of the difference between the pretreatment and posttreatment measurement values between the groups, no significant difference was found between PEMF and Sham groups according to the NRS (p=0.165), UCLA Shoulder Scale (p=0.141), and SPADI (p=0.839) scores. CONCLUSIONS: In our study, a combination of PEMF therapy with conventional physical therapy modalities was not found to be superior to the conventional therapy alone, and adding it to the routine treatment of symptomatic supraspinatus tear would not provide any additional benefit.
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Humans , Electric Stimulation Therapy , Magnetic Field Therapy , Treatment Outcome , Rotator Cuff , Shoulder Pain/therapy , Electromagnetic FieldsABSTRACT
OBJECTIVE: To analyze the current status of occupational exposure to power frequency electromagnetic field in converter stations. METHODS: Eight converter stations with voltage levels of ±500 kV and ±800 kV within normal operation were selected as the research subjects using the typical sampling method. Power frequency electric field and power frequency magnetic field strengths were measured and calculated according to the GBZ/T 189.3-2018 Measurement of Physical Agents in Workplace--Part 3: Electric Field and Magnetic Field between 1 Hz and 100 kHz. The GBZ 2.2-2007 Occupational Exposure Limits for Hazardous Factors in the Workplace--Part 2: Physical Factors were used to evaluate whether the power frequency electric field strength exceeds the regulatory limit(the occupational exposure limit of power frequency electric field in 8 hours workplace is 5.000 kV/m). Meanwhile, the test results were evaluated according to the short-term occupational exposure limit of 50 Hz electric field and magnetic field recommended by the International Committee on Nonionizing Radiation Protection in 2010 that are 10.000 kV/m and 1 000.00 μT. RESULTS: The power frequency electric field and magnetic field strengths of 582 working environment detection points were measured. The median and 0-100 th percentile of power frequency electric field and power frequency magnetic field strength were 4.342(0.001-12.003) kV/m and 5.51(0.10-186.90) μT, respectively.The exceeding standard rate of power frequency electric field strength in converter station workplaces was 37.8%(220/582), which concentrated in 500 kV alternating current filter area and 500 kV alternating current field area. Among them, 5 detection points had power frequency electric field strength exceeding 10.000 kV/m. The magnetic flux density of all the detection points did not exceed 1 000.00 μT. The power frequency electric field strength in ultra-high voltage region was higher than that in high voltage region(P<0.01). There was no significant difference in power frequency magnetic field strength(P>0.05). There was no significant difference in power frequency electric field and magnetic field between rectifier stations and inverter stations(P>0.05). The 8 hours time weighted average(TWA) value of power frequency electric field strength of 8 converter station operators was 1.044-2.335 kV/m, which did not exceed the occupational exposure limit. CONCLUSION: The converter station operators might be exposed to excessive power frequency electric fields for a short time, but the 8 hours TWA value of the power frequency electric field meets the requirements of standards, and the power frequency magnetic field exposure strength also meets the requirements of the relevant standards.
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Objective To evaluate the impact of an external magnetic field on the dose distribution and electronic disequilibrium region around a Bebig type 60Co HDR brachytherapy source and to judge the feasibility of applying MRI scanner during brachytherapy.Methods The source model was established based on the Monte Carlo package Geant4 software.The simulated geometries consisted of the 60Co source inside a water phantom of 10.0cm× 10.0cm× 10.0cm in size.The magnetic field strength of the 0T,1.5T and 3.0T was considered,respectively.The voxels with a size of 0.2 mm,0.5 mm and 0.5 mm were established along the x-,y-and z-axis.The influence of the magnetic field on the Kerma (kinetic energy released to matter) distribution and dose distribution within the 10.0mm region from the source center was evaluated.Furthermore,the ratio of the Kerma to dose as a function of the distance to the center source was acquired.Results The 1.5T magnetic field exerted no effect on the dose distribution adjacent to 60Co HDR brachytherapy source,whereas3.0T magnetic field caused significant increase in the dose distribution within r＜6 mm from the source center.The dose distribution was increased by 40％ at r=5.4 mm from the source center.The ratio of Kerma to dose was less than 1 within the region of 1.2 mm＜r＜6.0 mm,suggesting that 3.0T magnetic field can lead to electronic disequilibrium within a larger region from the source center.Conclusions For Bebig 60Co HDR brachytherapy source,it is safe and reliable to apply1.5T external magnetic field.Nevertheless,3.0T magnetic field can cause high dose risk.Consequently,safety assessment and verification should be delivered prior to clinical application.
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BACKGROUND: The clinical effect of spinal cord injury is usually unfavorable due to the lack of axon regeneration and the formation of glial scar. Schwann cells, as the support cells for nerve regeneration, have poor migration ability in the central nervous system with abundant astrocytes, which limit its effect on axon regeneration. OBJECTIVE: To explore the effect on the migration of Schwann cells containing superparamagnetic nanoparticles loaded with chondroitinase ABC (ChABC) in the region of astrocytes in the external magnetic field. METHODS: Schwann cells and astrocytes were extracted from sciatic nerves and brachial plexus and cerebral cortex of Sprague-Dawley rats of postnatal day 1 to 3. Cell purity was identified by immunofluorescence staining. The toxicity of superparamagnetic nanoparticles (PEI-SPIONs) to Schwann cells was analyzed by live/dead cell staining. Schwann cells were transfected with PEI-SPIONS in an external magnetic field of 1.4Td for 2 days. The optimal transfection concentration of PEI-SPIONS used was 2 mg/L and the optimal mass ratio of PEI-SPIONS to ChABC was 1:4. Cell migration test was used to evaluate the migration ability of not-treated Schwann cells, PEI-SPIONs/ ChABC transfected Schwann cells, and PEI-SPIONs/ChABC transfected Schwann cells in an external magnetic field. RESULTS AND CONCLUSION: The purity of Schwann cells and astrocytes reached to (91.7±1.2)% and (93.3±2.2)%, respectively. Compared with the Schwann cells group, the number of PEI-SPIONs/ChABC-transfected Schwann cells that entered the region of astrocytes was significantly increased (P < 0.05). Under the external magnetic field, the number of PEI-SPIONs/ChABC-transfected Schwann cells that entered the region of astrocytes and the cell migration distance were significantly increased as compared with the Schwann cells group (P < 0.005). In summary, PEI-SPIONs/ChABC transfection can enhance the ability of Schwann cells to break the glial scar, and increase the fusion of astrocytes. Under the guidance of external magnetic field, the migration ability of Schwann cells is significantly elevated. This method may be a new strategy to promote nerve regeneration after spinal cord injury.
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As drug carriers, magnetic nanoparticles can specifically bind to tumors and have the potential for targeted therapy. It is of great significance to explore non-invasive imaging methods that can detect the distribution of magnetic nanoparticles. Based on the mechanism that magnetic nanoparticles can generate ultrasonic waves through the pulsed magnetic field excitation, the sound pressure wave equation containing the concentration information of magnetic nanoparticles was derived. Using the finite element method and the analytical solution, the consistent transient pulsed magnetic field was obtained. A three-dimensional simulation model was constructed for the coupling calculation of electromagnetic field and sound field. The simulation results verified that the sound pressure waveform at the detection point reflected the position of magnetic nanoparticles in biological tissue. Using the sound pressure data detected by the ultrasonic transducer, the B-scan imaging of the magnetic nanoparticles was achieved. The maximum error of the target area position was 1.56%, and the magnetic nanoparticles regions with different concentrations were distinguished by comparing the amplitude of the boundary signals in the image. Studies in this paper indicate that B-scan imaging can quickly and accurately obtain the dimensional and positional information of the target region and is expected to be used for the detection of magnetic nanoparticles in targeted therapy.
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Acoustics , Computer Simulation , Magnetics , Magnetite Nanoparticles , TomographyABSTRACT
Abstract Phenolic compounds are one of the main groups of secondary metabolites in plants and are known for their antioxidant activity. Rosmarinus officinalis L. (rosemary) contains different phenolic compounds including carnosol, carnosic acid and rosmarinic acid. In Cuba, rosemary cultivation is limited because it is difficult to propagate and has a low yield. As a result, it was removed from the Herbal Medicine National Formulary. However, the National Public Health System has a strong interest in rosemary because of its value as a natural antioxidant medicine. Irrigation with water treated with a static magnetic field (SMF) is a possible strategy to increase rosemary yield. This technology has been applied to accelerate plant growth and increase crop quality. The aim of this study was to evaluate the content of phenolic compounds and antioxidant activity in aqueous leaf extracts from plants irrigated with SMF-treated water in comparison to control plants. Significant differences in phenolic content and antioxidant activity were observed between aqueous extracts of control plants and plants irrigated with SMF-treated water. Therefore, irrigation with SMF-treated water is a promising technology to improve the cultivation of rosemary as a raw material to obtain pharmaceutical products with high antioxidant activities.
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Rosmarinus/chemistry , Agricultural Irrigation/methods , Magnetic Fields , Antioxidants/analysis , Chromatography, High Pressure LiquidABSTRACT
Objective: To investigate the impact of MR fringe magnetic field on the electron beam characteristics of the electron gun in the MRI-guided radiotherapy (MRIgRT). Methods Electromagnetic field analysis software was used to simulate the beam characteristics of both Litton L2087 electron gun and Varian 600C electron gun under different magnetic field strengths for the in-line MRIgRT configuration. Results Two electron guns exhibited qualitatively similar behavior in the fringe magnetic field. As field strength increased, the current emitted by the cathode increased slowly, which could increase up to 2.72% and 1.93% from the original value without external magnetic field for Litton L2087 and Varian 600C electron gun, respectively. The current at the anode exit started to decrease after the initial plateau, and after reaching a minimum value, the current started to increase slowly, and the current loss could reach up to 80.25% and 73.48% of the initial value, respectively. At high values of the field strength, the beam radius changed periodically. Beam root mean square emittance fluctuated under different magnetic field strengths. Conclusion For in-line MRIgRT configuration, the fringe magnetic field can affect the trajectory of the beam and cause a large amount of current loss in the electron gun, and the beam RMS emittance varies greatly.
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Objective: To investigate the inhibitory effect of a combination of static magnetic field (SMF) and extremely low frequency-electromagnetic field (ELF-EMF) on the proliferation of tumor cells, and its causal relationship with the induction of intracellular reactive oxygen species (ROS) after exposure. Methods: The intensities of SMF and 50 Hz ELF-EMF both changed periodically and generated a magnetic field (MF) with a time-averaged intensity of 5.1 mT in the center of exposure area. The bronchial epithelium of human lung Beas-2B cells, human renal epithelial 293T cells, human nephroblastoma G401 cells, human gastric adenocarcinoma AGS cells, human pancreatic cancer BxPC cells and human neuroblastoma CHLA255 cells were exposured in MF for 2 h/d (continuous 3 days). The effects of the combined MF on the growth, proliferation, apoptosis and intracellular ROS concentration were detected by trype blue method, BrdU method, FCM method and DCFH-DA fluorescence probe method, respectively. Results: This combined MF showed no inhibitory effect on non-tumor cells including Beas-2B and 293T (both P > 0.05), while it showed inhibitory effect on tumor cells including G401, AGS, BxPC, and CHLA255 cells (all P < 0.01). G401 and CHLA255 cells were more sensitive to the MF, the inhibitory rate of G401 and CHLA255 cells at the third day of exposure was (29.41±0.81)% and (31.71±4.59)%, respectively. The apoptosis rate of G401 cells exposed to MF for 2 h/d was increased in 3 days (P < 0.05, P < 0.01 and P < 0.01). As compared with daily exposure for 2 h, the inhibition rate of daily exposure for 8 h induced another 10% increase (all P < 0.01). Furthermore, the combined MF exhibited more pronounced antitumor effect than that of SMF or ELF-EMF alone, including SMF with the same intensity of the combined field (all P < 0.01). The peak of intracellular ROS levels was reached shortly after initial exposure (1-2 h), for long before the peak of cell inhibition was reached (day 2-3 with accumulated exposure of 4-6 h). Continuous or intermittent increase of MF exposure did not result in further accumulation of intracellular ROS. However, the peak of ROS levels persisted to the next day after termination of exposure. Both SMF and ELF-EMF could induce the elevation of ROS, but without superimposition effect. Conclusion: Extending the exposure time of MF can improve its inhibitory effect on tumor cells. The antitumor effect of the combined MF is related to free radical damage, but this may be not the only mechanism.
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Objective To observe the influences of extremely low frequency magnetic fields irradiation in rats at different time points after traumatic brain injury (TBI).Methods According to the random number table method,450 SD rats were divided into blank control group,TBI group,electromagnetic field early irradiation group,electromagnetic field late irradiation group,and electromagnetic field early and late combined irradiation group (n=90).TBI models in rats of the later four groups were induced by connection of lateral hydraulic impact (LFP) equipment;the rats in the blank control group accepted the same operation,but did not connect to the LFP equipment.The rats in the electromagnetic field early irradiation group and electromagnetic field late irradiation group received electromagnetic field irradiation on 6 and 60 d after TBI for 15 consecutive d,respectively;and the rats in the electromagnetic field early and late combined irradiation group received twice consecutive electromagnetic field irradiation for 15 d on 6 and 60 d after TBI.Four h,15 d and 75 d after TBI,the hypoxia inducible factor-1α (HIF-1α) expression in the hippocampus of rats in each group was detected by immunohistochemical staining;TUNEL was used to detect cell apoptosis in hippocampal area of rats in each group;the contents of Evans blue (EB) and brain water in rat brain tissues were determined;the water maze experiment was used to test the learning and memory abilities of rats;HIF-1α protein expression in the hippocampal tissues of rats was detected by Western blotting.Results As compared with rats in the blank control group,rats in the TBI group,electromagnetic field early irradiation group,electromagnetic field late irradiation group,and electromagnetic field early and late combined irradiation group had significantly larger number of apoptotic cells in the hippocampus,statistically longer time boarding the escape platform,significantly higher HIF-1α protein expression at 4 h,15 d and 75 d after TBI (P＜0.05).As compared with rats in the TBI group,those in the electromagnetic field early irradiation group and electromagnetic field early and late combined irradiation group had significantly smaller number of apoptotic cells in the hippocampus,statistically shorter time boarding the escape platform,significantly lower HIF-1α protein expression,and significantly decreased EB content and brain water content 15 d after TBI (P＜0.05).As compared with rats in the TBI group,those in the electromagnetic field early irradiation group,electromagnetic field late irradiation group,and electromagnetic field early and late combined irradiation group had significantly smaller number of apoptotic cells in the hippocampus,statistically shorter time boarding the escape platform,significantly lower HIF-1α protein expression,and significantly decreased EB content and brain water content 75 d after TBI (P＜0.05).Conclusion The extremely low frequency magnetic fields irradiation is recommended in early and delayed stages of TBI;and exposure to extremely low frequency magnetic fields should be prolonged.
ABSTRACT
Portable low-cost magnetic resonance imaging (MRI) systems have the potential to enable “point-of-care” and timely MRI diagnosis, and to make this imaging modality available to routine scans and to people in underdeveloped countries and areas. With simplicity, no maintenance, no power consumption, and low cost, permanent magnets/magnet arrays/magnet assemblies are attractive to be used as a source of static magnetic field to realize the portability and to lower the cost for an MRI scanner. However, when taking the canonical Fourier imaging approach and using linear gradient fields, homogeneous fields are required in a scanner, resulting in the facts that either a bulky magnet/magnet array is needed, or the imaging volume is too small to image an organ if the magnet/magnet array is scaled down to a portable size. Recently, with the progress on image reconstruction based on non-linear gradient field, static field patterns without spatial linearity can be used as spatial encoding magnetic fields (SEMs) to encode MRI signals for imaging. As a result, the requirements for the homogeneity of the static field can be relaxed, which allows permanent magnets/magnet arrays with reduced sizes, reduced weight to image a bigger volume covering organs such as a head. It offers opportunities of constructing a truly portable low-cost MRI scanner. For this exciting potential application, permanent magnets/magnet arrays have attracted increased attention recently. A magnet/magnet array is strongly associated with the imaging volume of an MRI scanner, image reconstruction methods, and RF excitation and RF coils, etc. through field patterns and field homogeneity. This paper offers a review of permanent magnets and magnet arrays of different kinds, especially those that can be used for spatial encoding towards the development of a portable and low-cost MRI system. It is aimed to familiarize the readers with relevant knowledge, literature, and the latest updates of the development on permanent magnets and magnet arrays for MRI. Perspectives on and challenges of using a permanent magnet/magnet array to supply a patterned static magnetic field, which does not have spatial linearity nor high field homogeneity, for image reconstruction in a portable setup are discussed.