Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 24
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Asthma ; 61(4): 360-367, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37878325

RESUMO

OBJECTIVE: When selecting inhaled therapies, it is important to consider both the active molecules and the device. Extrafine formulation beclomethasone dipropionate plus formoterol fumarate (BDP/FF) has been available for some years delivered via pressurized metered-dose inhaler (pMDI). More recently, a breath-activated, multi-dose dry-powder inhaler (DPI), the NEXThaler, has been approved. The current study aimed to demonstrate the non-inferiority of BDP/FF delivered via the DPI vs. via the pMDI, in Chinese adults with asthma. METHODS: After a four-week run-in period, when all patients received BDP/FF pMDI 100/6 µg, two inhalations twice daily (BID), patients were randomized equally to BDP/FF pMDI or DPI, both 100/6 µg, two inhalations BID for 12 weeks. The primary objective was to demonstrate non-inferiority of BDP/FF DPI vs. BDP/FF pMDI in terms of average pre-dose morning peak expiratory flow (PEF) over the entire treatment period. RESULTS: Of 252 and 242 patients in the DPI and pMDI groups, respectively, 88.5% and 88.8% completed the study. The primary objective was met, with no statistically significant difference between the treatments in average pre-dose morning PEF, and with the lower limit of the 95% CI above the -15 L/min non-inferiority margin (adjusted mean difference: 5.25 L/min [95% CI: -0.56, 11.06]). Adverse events were reported by 48.4% and 49.6% patients in the DPI and pMDI groups, respectively, most mild or moderate. CONCLUSIONS: The NEXThaler DPI is a similarly effective device to the pMDI for the administration of BDP/FF in adults, so extending the options available for the management of asthma.


Assuntos
Antiasmáticos , Asma , Adulto , Humanos , Administração por Inalação , Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Beclometasona/uso terapêutico , China , Método Duplo-Cego , Combinação de Medicamentos , Inaladores de Pó Seco , Fumarato de Formoterol/uso terapêutico , Inaladores Dosimetrados , Resultado do Tratamento
2.
Polymers (Basel) ; 14(5)2022 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-35267869

RESUMO

In this work, we present the fabrication and characterization of bulk-heterojunction solar cells on monolayer graphene (MLG) with nickel-grids (Ni-grid) as semitransparent conductive electrode. The electrodes showed a maximum transmittance of 90% (calculated in 300-800 nm range) and a sheet resistance down to 35 Ω/□. On these new anodes, we fabricated TCO free BHJ-SCs using PTB7 blended with PC70BM fullerene derivative as active layer. The best device exhibited a power conversion efficiency (PCE) of 4.2% in direct configuration and 3.6% in inverted configuration. The reference solar cell, realized on the ITO glass substrate, achieved a PCE of 6.1% and 6.7% in direct and inverted configuration respectively; for comparison we also tested OSCs only with simple Ni-grid as semitransparent and conductive electrode, obtaining a low PCE of 0.7%. The proposed approach to realize graphene-based electrodes could be a possible route to reduce the overall impact of the sheet resistance of this type of electrodes allowing their use in several optoelectronic devices.

3.
ACS Appl Mater Interfaces ; 12(29): 32536-32547, 2020 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-32588625

RESUMO

Organic-inorganic lead halide perovskite has recently emerged as an efficient absorber material for solution process photovoltaic (PV) technology, with certified efficiency exceeding 25%. The development of low-temperature (LT) processing is a challenging topic for decreasing the energy payback time of perovskite solar cell (PSC) technology. In this context, the LT planar n-i-p architecture meets all the requirements in terms of efficiency, scalability, and processability. However, the long-term stability of the LT planar PSC under heat and moisture stress conditions has not been carefully assessed. Here, a detailed study on thermal and moisture stability of large-area (1 cm2) LT planar PSCs is presented. In particular, the key role in thermal stability of potassium iodide (KI) insertion in the perovskite composition is demonstrated. It is found that defect passivation of triple-cation perovskite by KI doping inhibits the halide migration induced by thermal stress at 85 °C and delays the formation of degradation subproducts. T80, defined as the time when the cell retains 80% of initial efficiency, is evaluated both for reference undoped devices and KI-doped ones. The results show that T80 increases 3 times when KI doping is used. Moreover, an HTL-free architecture where the Au top electrode is replaced with low-T screen-printable carbon paste is proposed. The combination of the carbon-based HTL-free architecture and KI-doped perovskite permits T80 to increase from 40 to 414 h in unsealed devices.

4.
Electromagn Biol Med ; 39(2): 176-182, 2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32149540

RESUMO

In this study, a correlation between cell channel α-helices displacement and the mitochondrial transmembrane potential after exposure of 3, 7, 15 and 24 h of neuronal-like cells to a uniform magnetic field at the intensity of 2 mT was shown. Fourier Transform Infrared (FTIR) Spectroscopy and fluorescence techniques were used to analyze the secondary structure of protein content and mitochondrial transmembrane potential, respectively. The main result of this study was represented by a significant inverse relation between the mitochondrial transmembrane potential and the intensity of the Amide I band that can be associated with time exposure. Given that mitochondrial transmembrane potential should be related to the gating state of voltage-dependent anion channel (VDAC) in mitochondrial membrane, this result could have a relevant role in medicine. Indeed, VDAC's irregular behavior can be associated with several varieties of mitochondria-associated pathologies and various forms of cancer and neurodegeneration.


Assuntos
Nanopartículas Magnéticas de Óxido de Ferro/efeitos adversos , Potencial da Membrana Mitocondrial , Neurônios/citologia , Canais de Ânion Dependentes de Voltagem/química , Canais de Ânion Dependentes de Voltagem/metabolismo , Linhagem Celular Tumoral , Humanos , Conformação Proteica em alfa-Hélice , Fatores de Tempo
5.
Electromagn Biol Med ; 39(2): 129-138, 2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32142387

RESUMO

The aim of this study was to highlight the existence of a correlation between Maillard reaction and protein aggregation in bovine meat as a function of power level and exposure time used by microwave heating. The obtained results are compared with those of convective heating. For this, Fourier Transform-Infrared Spectroscopy was used to analyze the effects of microwave heating on different samples of bovine meat cooked in microwave ovens at three power levels of 700, 900 and 1100 W, and in conventional electric oven at the temperature of 170°C. An increase in intensity of methylene vibration bands after microwave cooking at 700 W for 3 min was more than that which occurred after microwave cooking at 900 and 1100 W for 2 min, showing that Maillard reaction depends on exposure time to microwaves. Also, the ß-sheet contents at 1695 and 1635 cm-1 in meat samples heated for 2 min by microwave oven increased with increase in power level from 700 to 1100 W, showing that protein aggregation is strictly related to the power level of microwave heating. This result showed that an extended exposure time to microwave heating can significantly alter gastrointestinal digestive processes.


Assuntos
Digestão , Temperatura Alta , Reação de Maillard , Micro-Ondas , Agregados Proteicos , Carne Vermelha , Espectroscopia de Infravermelho com Transformada de Fourier , Animais , Bovinos
6.
Electromagn Biol Med ; 39(2): 97-108, 2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32138556

RESUMO

The aim of this study was to investigate the response of chromosomes in typical human and plant cells under applied low-frequency magnetic fields at low and high intensities. Neuronal-like cells and roots of Allium sativum and Vicia faba were used to investigate chromosome's response to a static and 50 Hz magnetic fields at intensities ranging from 1 mT to 0.8 T, generated by two Helmholtz coils driven by direct current or alternate current voltage. Vertex spectrometer and Olympus microscope with camera were used. A significant decrease in intensity of the phosphate bands in the DNA infrared region was observed by FTIR spectroscopy analysis after exposure of neuronal-like cells to static and 50 Hz magnetic field at low intensity of 1 mT, which can be explained assuming that uncoiling and unpackaging of chromatin constituents occurred after exposure. This effect was directly observed by microscope in roots of Allium sativum and Vicia faba under exposure to a static magnetic field at high intensity of 0.8 T. These findings can be explained assuming that exposure to both low- and high-intensity magnetic fields of chromosomes in typical human and plant cells induces uncoiling and unpackaging of chromatin constituents, followed by chromosome alignment towards the direction of applied magnetic field, providing further demonstration that magnetic fields can induce the orientation of organic macromolecules even at low-intensity values.


Assuntos
Aberrações Cromossômicas , Campos Magnéticos/efeitos adversos , Linhagem Celular Tumoral , Alho/genética , Humanos , Neurônios/metabolismo , Vicia faba/genética
7.
Electromagn Biol Med ; 38(4): 271-278, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31293188

RESUMO

The aim of this paper was to study the response of methyl (CH3) and methylene (CH2) vibration bands in amino acids of some typical proteins diluted in bidistilled water solution after exposure to a high-frequency electromagnetic fields using Fourier Transform Infrared (FTIR) Spectroscopy. Hemoglobin in H2O solution and bovine serum albumin and myoglobin diluted in different D2O solutions were exposed for 4 h to a power density of 0.95 W/m2 at the frequency of 1750 MHz, emitted by operational mobile phones Nokia model 105 and Samsung model GT-E1270, in order to study the response of stretching vibrations of CH3 and CH2 that are in amino acids of those proteins. The main result was that CH3 stretching bands increased significantly in myoglobin in D2O solution because this protein is represented by a single protein chain so that the torque induced by the applied field is larger than that induced on the other two proteins. Otherwise, CH2 stretching vibrations decreased in intensity significantly for all exposed proteins. This result can be explained as well, assuming that, given a fixed volume, a decrease of population of CH2 occurred after exposure because of the alignment of proteins α-helices along the direction of the applied electromagnetic field.


Assuntos
Proteínas Sanguíneas/química , Campos Eletromagnéticos/efeitos adversos , Vibração , Água/química , Adulto , Humanos , Modelos Moleculares , Conformação Proteica em alfa-Hélice , Soluções , Espectrofotometria Infravermelho , Adulto Jovem
8.
Int J Radiat Biol ; 95(6): 781-787, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30668250

RESUMO

Purpose: To study the response of neuronal-like cells to an applied static or low-frequency magnetic field. Materials and methods: Fourier Transform Infrared (FTIR) Spectroscopy was used to investigate the overall behavior of SH-SY5Y neuronal-like cells exposed to a static or 50 Hz magnetic fields at intensities up to 1 mT generated by two Helmholtz coils driven by direct current or alternate current voltage. The Helmholtz coils were placed into an incubator in a 5% CO2/95% air humidified at 37 °C. Results: A significant increase in intensity of the Amide I band and of CH2 stretching vibrations in neuronal-like FTIR spectra appeared after 6 h exposure to static or 50 Hz magnetic fields. Conclusions: These findings can be easily explained assuming that proteins α-helices and lipids contents in cellular membrane aligned toward the direction of the applied magnetic field after exposure, inducing an increase of ions flux across cellular membrane channels after exposure to a magnetic field, changing cellular functions.


Assuntos
Campos Magnéticos , Neurônios/citologia , Espectrofotometria Infravermelho , Linhagem Celular Tumoral , Humanos
9.
ACS Nano ; 12(11): 10736-10754, 2018 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-30240189

RESUMO

Interface engineering of organic-inorganic halide perovskite solar cells (PSCs) plays a pivotal role in achieving high power conversion efficiency (PCE). In fact, the perovskite photoactive layer needs to work synergistically with the other functional components of the cell, such as charge transporting/active buffer layers and electrodes. In this context, graphene and related two-dimensional materials (GRMs) are promising candidates to tune "on demand" the interface properties of PSCs. In this work, we fully exploit the potential of GRMs by controlling the optoelectronic properties of molybdenum disulfide (MoS2) and reduced graphene oxide (RGO) hybrids both as hole transport layer (HTL) and active buffer layer (ABL) in mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite (MAPbI3)-based PSCs. We show that zero-dimensional MoS2 quantum dots (MoS2 QDs), derived by liquid phase exfoliated MoS2 flakes, provide both hole-extraction and electron-blocking properties. In fact, on one hand, intrinsic n-type doping-induced intraband gap states effectively extract the holes through an electron injection mechanism. On the other hand, quantum confinement effects increase the optical band gap of MoS2 (from 1.4 eV for the flakes to >3.2 eV for QDs), raising the minimum energy of its conduction band (from -4.3 eV for the flakes to -2.2 eV for QDs) above the one of the conduction band of MAPbI3 (between -3.7 and -4 eV) and hindering electron collection. The van der Waals hybridization of MoS2 QDs with functionalized reduced graphene oxide (f-RGO), obtained by chemical silanization-induced linkage between RGO and (3-mercaptopropyl)trimethoxysilane, is effective to homogenize the deposition of HTLs or ABLs onto the perovskite film, since the two-dimensional nature of RGO effectively plugs the pinholes of the MoS2 QD films. Our "graphene interface engineering" (GIE) strategy based on van der Waals MoS2 QD/graphene hybrids enables MAPbI3-based PSCs to achieve a PCE up to 20.12% (average PCE of 18.8%). The possibility to combine quantum and chemical effects into GIE, coupled with the recent success of graphene and GRMs as interfacial layer, represents a promising approach for the development of next-generation PSCs.

10.
Electromagn Biol Med ; 37(3): 155-168, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30019948

RESUMO

Samples of human hemoglobin, bovine serum albumin, lysozyme and myoglobin were used as prototype of proteins to investigate their response to exposure to high frequency electromagnetic fields (HF-EMFs), in order to study possible application to the treatment of cancer. To this aim, Fourier-transform infrared spectroscopy was used in the infrared region. The most evident result which appeared after 3 h exposure to HF-EMFs was a significant increase in intensity of the Amide I band and of CH2 bending vibrations, showing that the proteins aligned toward the direction of the field. In addition, proteins' unfolding and aggregation occurred after exposure to HF-EMFs. These findings can be explained assuming a resonance interaction between the natural frequencies of proteins and HF-EMFs, which can induce iperpolarization of cells. Given that cancerous tissues were found to have natural frequencies different from natural frequencies of normal tissues, we can hypothesize to irradiate cancerous tissues using EMFs at natural frequencies of cancer cells, causing resonant interaction with cellular membrane channels, inducing increasing of ions' flux across cellular channels and damaging the cellular functions of cancer cells.


Assuntos
Campos Eletromagnéticos , Magnetoterapia , Neoplasias/metabolismo , Neoplasias/terapia , Proteínas/metabolismo , Animais , Membrana Celular/metabolismo , Membrana Celular/efeitos da radiação , Humanos , Conformação Proteica em alfa-Hélice , Proteínas/química
11.
J Vasc Access ; 18(6): 522-529, 2017 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-28862723

RESUMO

INTRODUCTION: In a previous paper, the authors investigated the mechanical behavior of several commercial polyurethane peripherally inserted central venous catheters (PICCs) in their 'brand new' condition. The present study represents a second step of the research activity and aims to investigate possible modifications of the PICC mechanical response, induced by long-term conservation in in vivo-like conditions, particularly when used to introduce oncologic drugs. METHODS: Eight 5 Fr single-lumen catheters from as many different vendors, were examined. Several specimens were cut from each of them and kept in a bath at 37°C for 1, 2, 3 and 6 months. Two fluids were used to simulate in vivo-like conditions, i.e. ethanol and Ringer-lactate solutions, the first being chosen in order to reproduce a typical chemical environment of oncologic drugs. The test plan included swelling analyses, uniaxial tensile tests and dynamic mechanical thermal analysis (DMTA). RESULTS AND CONCLUSIONS: All tested samples were chemically and mechanically stable in the studied conditions, as no significant weight variation was observed even after six months of immersion in ethanol solution. Uniaxial tensile tests confirmed such a response. For each PICC, very similar curves were obtained from samples tested after different immersion durations in the two fluid solutions, particularly for strains lower than 10%.


Assuntos
Cateterismo Venoso Central/instrumentação , Cateterismo Periférico/instrumentação , Cateteres de Demora , Cateteres Venosos Centrais , Poliuretanos/química , Desenho de Equipamento , Falha de Equipamento , Etanol/química , Soluções Isotônicas/química , Teste de Materiais , Lactato de Ringer , Estresse Mecânico , Temperatura , Resistência à Tração , Fatores de Tempo
12.
Electromagn Biol Med ; 36(3): 279-288, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28632082

RESUMO

The aim of this article was to study the effects of mobile phone electromagnetic waves at 1750 MHz on the Amide I and Amide II vibration bands of some proteins in bidistilled water solution by means of Fourier transform infrared (FTIR) spectroscopy and Fourier self-deconvolution (FSD) analysis. The proteins that were used for the experiment were hemoglobin, myoglobin, bovine serum albumin and lysozyme. The exposure system consisted of microwaves emitted by an operational mobile phone at the frequency at 1750 MHz at the average power density of 1 W/m2. Exposed and control samples were analyzed using FTIR spectroscopy and FSD analysis. The main result was that Amide I band of the proteins that were used increased significantly (p < 0.05) after 4 h of exposure to MWs, whereas Amide II band did not change significantly. This result can be explained assuming that the α-helix structure of the proteins aligned itself with the direction of the electromagnetic field due to the alignment of C = O stretching and N - H bending ligands that are oriented along with the α-helix axis that give rise to the Amide I mode.


Assuntos
Campos Eletromagnéticos , Conformação Proteica em alfa-Hélice , Espectroscopia de Infravermelho com Transformada de Fourier , Hemoglobinas , Muramidase , Mioglobina , Soroalbumina Bovina , Vibração , Água
13.
Bioelectromagnetics ; 38(6): 447-455, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28453873

RESUMO

In this study, we report the effects of static magnetic fields (SMFs) at 200 mT on different hemoglobin aqueous solutions, in the absence and in the presence of sucrose and trehalose, studied by FTIR spectroscopic techniques. Significant decrease in intensity of Amide I and Amide II vibration bands was observed after 6 h exposure for hemoglobin in bidistilled water solution. Also, it was observed that the decrease in intensity of the Amide I band was larger than the Amide II after exposure. This result can be explained assuming that an SMF induces increase of hydrogen bonding in hemoglobin in bidistilled water solution. In particular, the use of second-derivative analysis highlighted two absorption peaks at 1907 and 2022 cm-1 that can be attributed to nitrogen monoxide vibration and antisymmetric stretch of azide ion bound, respectively. These vibrations increased significantly after exposure to the SMF (P < 0.01). This result can be explained assuming that exposure to an SMF induces the orientation of nitrogen monoxide and azide ion ligands toward the direction of the field. Finally, it was observed that the addition of sucrose and trehalose in hemoglobin aqueous solution inhibited such alterations, suggesting that bioprotective effectiveness of these disaccharides occurs after exposure to an SMF. Bioelectromagnetics. 38:447-455, 2017. © 2017 Wiley Periodicals, Inc.


Assuntos
Azidas/química , Destilação , Hemoglobinas/química , Campos Magnéticos , Óxido Nítrico/química , Vibração , Água/química , Amidas/química , Humanos , Soluções
14.
Int J Radiat Biol ; 92(7): 395-403, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27173917

RESUMO

PURPOSE: To investigate the role of hydrogen bonding and protein unfolding in human SH-SY5Y neuronal-like cells under exposure to a 50 Hz magnetic field (MF) at the intensity of 1 mT. MATERIALS AND METHODS: Neuronal-like cells were placed into an incubator in a 5% CO2/95% air humidified at the temperature of 37.1 °C and exposed for 4 h to a 50 Hz MF at 1 mT. The exposure system consisted of two Helmholtz coils driven by AC voltage at 50 Hz. Exposed and control samples were studied using Fourier Transform Infrared (FTIR) Spectroscopy. RESULTS: The vibration bands of the methylene group increased significantly after 4 h of exposure. A significant shift to low energies of the Amide I band and an increase in the intensity of the parallel and antiparallel ß-sheet structures with respect to the α-helix component were observed after exposure. The Amide II frequency did not change significantly whereas a relative increase of its integrated area with respect to Amide I mode occurred after exposure. CONCLUSIONS: These results can be explained assuming that both the mechanisms of protein aggregation as well as the increase in hydrogen bonding occurred in neuronal-like cells under exposure to a 50 Hz MF.


Assuntos
Ligação de Hidrogênio/efeitos da radiação , Campos Magnéticos , Neurônios/metabolismo , Neurônios/efeitos da radiação , Agregados Proteicos/efeitos da radiação , Desdobramento de Proteína/efeitos da radiação , Linhagem Celular , Relação Dose-Resposta à Radiação , Eletricidade , Humanos , Agregados Proteicos/fisiologia , Doses de Radiação
15.
Bioelectromagnetics ; 37(2): 99-107, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26833949

RESUMO

Effects of exposure of 4 h to mobile phones microwaves at 1765 MHz at a power density around 940 mW/m(2) on four typical proteins (hemoglobin in H2 O solution, and myoglobin, bovine serum albumin, and lysozyme in D2 O solution) were studied by means of Fourier Transform Infrared spectroscopy and Fourier self-deconvolution analysis. Increase in intensity of parallel ß-sheet component around 1635 cm(-1) was observed after exposure of hemoglobin, myoglobin, and bovine serum albumin, showing that a mechanism of unfolding occurred after exposure, whereas no appreciable change in the amide I region occurred after lysozyme exposure. In addition, a relationship between protein dipole moment and protein unfolding rate was demonstrated with a correlation coefficient r = 0.973 and 95% confidence interval.


Assuntos
Micro-Ondas , Proteínas/química , Vibração , Adolescente , Adulto , Animais , Bovinos , Óxido de Deutério/química , Humanos , Estrutura Secundária de Proteína/efeitos da radiação , Adulto Jovem
16.
J Vasc Access ; 17(2): 175-81, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26349887

RESUMO

PURPOSE: This study describes a comparative analysis of eight commercial polyurethane, single-lumen peripherally inserted central venous catheters (PICCs) from different vendors. The aim was to investigate the mechanical response of the catheters providing objective and quantitative data to support a comparison among them. Such data could help nurses and physicians to select a central venous catheter (CVC) not only on the basis of the expected dwell duration or of the assessment of the vessels at the desired insertion site but also of the chemical and mechanical properties of the CVC and of the projected response of the body to these properties. METHODS: An experimental procedure was defined and tests were performed to assess some main characteristics of the PICC lines, including macro and microgeometric features, chemical and physical properties, and mechanical response. Preliminary measurements were performed to accurately define all geometric characteristics, including length, inner and outer diameters, and any inherent initial curvature of the catheter. Micro-geometric features were investigated using surface roughness analysis, optical microscopy, and scanning electron microscopy. Mechanical properties were studied by means of dynamic mechanical thermal analysis, simple uniaxial tensile tests, and kinking tests. RESULTS: Results are discussed in order to compare the different PICC lines. In particular, they show that polyurethane catheters can have a different mechanical behavior, which might play a role in the onset of pathologic processes and result in an increased risk and incidence of catheter-related complications. CONCLUSIONS: This study provides useful information that can help identifying and facilitate the choice of a PICC.


Assuntos
Cateterismo Periférico/instrumentação , Cateteres de Demora , Cateteres Venosos Centrais , Poliuretanos/química , Elasticidade , Desenho de Equipamento , Falha de Equipamento , Humanos , Teste de Materiais , Estresse Mecânico , Propriedades de Superfície , Temperatura , Resistência à Tração , Viscosidade
17.
Bioelectromagnetics ; 34(8): 618-29, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24217848

RESUMO

Biological effects of man-made electromagnetic fields (EMFs) have been studied so far by experimental approaches exposing animals and cell cultures to EMFs. However, the evidence for cell toxicity induced by static magnetic field (SMF) is still uncertain. We investigated the effects produced by the exposure of human SH-SY5Y neuronal-like cells to a uniform magnetic field at intensities of 2.2 mT, which is less than the recommended public exposure limits set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). A decrease of membrane mitochondrial potential up to 30% was measured after 24 h of exposure to SMF in SH-SY5Y cells, and this effect was associated with reactive oxygen species production increase. Fourier transform infrared spectroscopy (FTIR) analysis showed that exposure to a static magnetic intensity around 2.2 mT changed the secondary structure of cellular proteins and lipid components. The vibration bands relative to the methylene group increased significantly after 4 h of exposure, whereas further exposure up to 24 h produced evident shifts of amide I and II modes and a relative increase in ß-sheet contents with respect to α-helix components. Our study demonstrated that a moderate SMF causes alteration in cell homeostasis, as indicated by FTIR spectroscopy observations of changes in protein structures that are part of cell response to magnetic field exposure.


Assuntos
Campos Magnéticos/efeitos adversos , Neurônios/citologia , Espécies Reativas de Oxigênio/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Linhagem Celular Tumoral , Sobrevivência Celular , Humanos , Potencial da Membrana Mitocondrial , Neurônios/metabolismo , Fatores de Tempo
18.
Oxid Med Cell Longev ; 2013: 414393, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23970948

RESUMO

SH-SY5Y neuroblastoma cells were used as an experimental model to study the effects of 50 Hz electromagnetic field, in the range from 50 µ T to 1.4 mT. Fourier transform infrared spectroscopy analysis evidenced a reduction in intensity of the amide A band and a slight increase of vibration bands at 2921 cm(-1) and 2853 cm(-1) corresponding to methylene groups. A further increase of the magnetic field intensity of exposure up to 0.8 mT and 1.4 mT produced a clear increase in intensity of CH2 vibration bands. Moreover, it has been observed some alterations in the amide I region, such as a shifted peak of the amide I band to a smaller wavenumber, probably due to protein conformational changes. These results suggested that exposure to extremely low electromagnetic fields influenced lipid components of cellular membrane and the N-H in-plane bending and C-N stretching vibrations of peptide linkages, modifying the secondary structures of α -helix and ß -sheet contents and producing unfolding process in cell membrane proteins. The observed changes after exposure to 50 Hz electromagnetic field higher than 0.8 mT were associated with a significant reduction of cell viability and reduced mitochondrial transmembrane potential.


Assuntos
Campos Eletromagnéticos , Potencial da Membrana Mitocondrial/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Linhagem Celular Tumoral , Sobrevivência Celular/fisiologia , Humanos , Espectrofotometria Infravermelho
19.
Artigo em Inglês | MEDLINE | ID: mdl-24779229

RESUMO

Measurements of power density emitted by a mobile phone were carried out as a function of the sound frequency transmitted by a sound generator, ranging from 250 to 14000 Hz. Output power density was monitored by means of the selective radiation meter Narda SRM 3000 in spectrum analysis mode, and the octave frequency analysis of each tone used for the experimental design was acquired by the sound level meter Larson Davis LxT Wind. Vodafone providers were used for mobile phone calls with respect to various local base station in Southern-Italy. A relationship between the mobile phone microwaves power density and the sound frequencies transmitted by the sound generator was observed. In particular, microwaves power density level decreases significantly at sound frequency values larger than 4500 Hz. This result can be explained assuming that discontinuous transmission mode of global system for mobile communications is powered not only in silence-mode, but also at frequencies larger than 4500 Hz.

20.
World J Biol Chem ; 3(2): 34-40, 2012 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-22371824

RESUMO

AIM: To investigate putative biological damage caused by GSM mobile phone frequencies by assessing electromagnetic fields during mobile phone working. METHODS: Neuron-like cells, obtained by retinoic-acid-induced differentiation of human neuroblastoma SH-SY5Y cells, were exposed for 2 h and 4 h to microwaves at 1800 MHz frequency bands. RESULTS: Cell stress response was evaluated by MTT assay as well as changes in the heat shock protein expression (Hsp20, Hsp27 and Hsp70) and caspase-3 activity levels, as biomarkers of apoptotic pathway. Under our experimental conditions, neither cell viability nor Hsp27 expression nor caspase-3 activity was significantly changed. Interestingly, a significant decrease in Hsp20 expression was observed at both times of exposure, whereas Hsp70 levels were significantly increased only after 4 h exposure. CONCLUSION: The modulation of the expression of Hsps in neuronal cells can be an early response to radiofrequency microwaves.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...