جستجوی مقالات مرتبط با کلیدواژه « magnetic field » در نشریات گروه « پزشکی »

Brain cancer is recognized as one of the deadliest cancers due to late detection and limitations of therapies. Glioblastoma occurs in different parts of the central nervous system and is the second leading cause of cancer death in people. There are many problems for the treatment of cancer cells. One of the limiting factors is the resistance of cancer cells to chemotherapy drugs. The use of nanoparticles (NPs) is an effective method for overcoming this problem.

Fe3O4 NPs were synthesized, and the size and morphology of NPs were determined by transmission electron microscopy, X-ray photoelectron spectroscopy, and Dynamic Light Scattering. The U87-MG cell line was cultured in Dulbecco’s modified Eagle medium and treated with nano, nano-lomustine, lomustine, and complex with/without magnetic fields. Finally, half maximal inhibitory concentration (IC50), MTT assay, and caspase8 and caspase9 expression were evaluated, and the data were analyzed with SPSS software.

Our results demonstrated that cell apoptosis increased in lomustine and complex groups, especially with the magnetic field (P > 0.05). Based on caspase9 expression analysis, this rate was increased with the magnetic field vs. its absence (P > 0.05).

These findings indicated that a magnetic field, in addition to reducing the effective dose of lomustine, affects apoptosis with a change in the expression of genes involved in this process.

Lack of high-quality sleep causes serious side effects like anxiety and changes in plasma concentration of oxalate. The current study aimed to investigate the impact of local extremely low frequency magnetic fields (ELF-MFs) on inducing sleep (sleepiness) and anxiety in male rats.

In this experimental study, 40 male rats were allocated in four groups (n=10). The ELF-MFs exposure (0, 10 and 18 Hz) was applied with intensity 200µT for three days (10 min/day). Sham-treated animal did not receive ELF-MF. Serum level of oxalic acid (OA) and sleepiness were measured both before first and after last exposure to ELF-MF or sham. Anxiety, sleepiness and OA were measured by using elevated plus maze, open-field test (OFT) and ELISA test, respectively.

Comparison of oxalate levels between before and after exposure to ELF-MF revealed that ELF-MF (10 Hz) decreased the serum level of oxalate (p<0.05). Comparison of the percent of open:closed arm entry (in elevated plus maze) between before and after exposure to ELF-MF revealed significant differences. Also, frequency, velocity and distance moved were decreased in the open-field test.

Results of the present study demonstrated that ELF-MF with short time exposure may modulate the metabolism of OA and may modulate anxiety-like behavior or kind of induction of sleepiness in male rats.

Extremely low-frequency magnetic field (ELF-MF) exposure, as a targeted tumor therapy, presents severalpotential advantages. In this research, we investigated effects of different ELF-MF intensities on cell viability and expression levels of the mammalian target of rapamycin (mTOR) and hsa_circ_100338 in the normal fibroblast (Hu02) and human gastric adenocarcinoma (AGS) cell lines.

In this experimental study, cell lines of AGS and Hu02, were cultured under the exposure of ELFMF with magnetic flux densities (MFDs) of 0.25, 0.5, 1 and 2 millitesla (mT) for 18 hours. The 3-(4, 5-dimethylthiazoyl-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to evaluate the cell viability. Relative expression of mTOR and hsa_circ_100338 RNAs was estimated by quantitative real-time polymerase chain reaction (qRT-PCR) technique.

Viability of the normal cells was significantly increased at MFDs of 0.5, 1 and 2 mT, while viability of the tumor cells was significantly decreased at MFD of 0.25 and increased at MFD of 2 mT. Expression level of mTOR was significantly increased at the all applied MFDs in the normal cells, while it was significantly decreased at MFDs of 0.25 and 0.5mT in the tumor cells. MFDs of 1 and 2 mT in tumor cells inversely led to the increase in mTOR expression. hsa_circ_100338 was downregulated in MFD of 0.25 mT and then it was increased parallel to the increase of MFD in the normal and tumor cells.

Results of the present study indicated that ELF-MF at MFDs of 0.25 and 0.5 mT can lead to decrease in the both mTOR and hsa_circ_100338 expression levels. Given the role of mTOR in cell growth, proliferation and differentiation, in addition to the potential role of hsa_circ_100338 in metastasis, expression inhibition of these two genes could be a therapeutic target in cancer treatment.

Tendon repair strategies usually are accompanied by pathological mineralization and scar tissue formation that increases the risk of re-injuries. This study aimed to establish an efficient tendon regeneration method simultaneously with a reduced risk of ectopic bone formation.

In this experimental study, tenogenic differentiation was induced through transforming growth factor- β3 (TGFB3) treatment in combination with the inhibiting concentrations of bone morphogenetic proteins (BMP) antagonists, gremlin-2 (GREM2), and a Wnt inhibitor, namely sclerostin (SOST). The procedure’s efficacy was evaluated using real-time polymerase chain reaction (qPCR) for expression analysis of tenogenic markers and osteochondrogenic marker genes. The expression level of two tenogenic markers, SCX and MKX, was also evaluated by immunocytochemistry. Sirius Red staining was performed to examine the amounts of collagen fibers. Moreover, to investigate the impact of the substrate on tenogenic differentiation, the nanofibrous scaffolds that highly resemble tendon extracellular matrix was employed.

Aggregated features formed in spontaneous normal culture conditions followed by up-regulation of tenogenicand osteogenic marker genes, including SCX, MKX, COL1A1, RUNX2, and CTNNB1. TGFB3 treatment exaggeratedmorphological changes and markedly amplified tenogenic differentiation in a shorter period of time. Along with TGFB3 treatment, inhibition of BMPs by GREM2 and SOST delayed migratory events to some extent and dramatically reduced osteo-chondrogenic markers synergistically. Nanofibrous scaffolds increased tenogenic markers while declining the expression of osteo-chondrogenic genes.

These findings revealed an appropriate in vitro potential of spontaneous tenogenic differentiation of eq- ASCs that can be improved by simultaneous activation of TGFB and inhibition of osteoinductive signaling pathways.

Exogenous electrical stimulation of the skin may mimic its endogenous bioelectric currents. In this study, a combination of direct current (DC) and magnetic field (MF) was investigated in an excision wound model in rats.

A circular wound was created on the posterior of the neck, and an electrode was fixed in the wound center. Rats were divided into sham, DC (600 µA), MF (~0.8 T), and magnet-direct current (MDC) groups. The study was conducted in 14 days with 20-min treatment daily.

The DC and MDC groups had higher healing percentages (P < 0.01) with mean differences of -13.42 and -15.63, respectively. Direct current on days 2, 5, and 6, and MDC on days 8, 9, 10, 11, 12, and 13 showed higher wound closing. In the DC-treated group, angiogenesis was improved on day 7. In MDC-treated rats, angiogenesis and fibroplasia were improved on day 13. The MF and MDC groups had lower granulation thicknesses on day 7. Granulation thickness increased on day 13 in the MF and MDC groups, while it decreased in the DC group. Direct current treatment improved healing in the first half of the study period, whereas MDC enhanced it in the second half, overtaking DC. From day 7, the magnet group's healing started to overtake the control group slightly in the last four days.

To accelerate wound healing, we suggest applying DC in the first days of wounding and MDC in the following days.

Extremely Low-Frequency Electromagnetic Fields (ELF-EMFs) have gathered significant consideration for their possible pathogenicity. However, their effects on the nervous system’s functions were not fully clarified. This study aimed to assay the impact of ELF-EMFs with different intensities on memory, anxiety, antioxidant activity, β-amyloid (Aβ) deposition, and microglia population in rats. 

Fifty male adult rats were randomly separated into 5 groups; 4 were exposed to a flux density of 1, 100, 500, and 2000 microtesla (µT), 50 Hz frequency for one h/day for two months, and one group as a control group. The control group was without ELF-EMF stimulation. After 8 weeks, passive avoidance and Elevated Plus Maze (EPM) tests were performed to assess memory formation and anxiety-like behavior, respectively. Total free thiol groups and the index of lipid peroxidation were evaluated. Additionally, for detection of Aβ deposition and stained microglia in the brain, anti-β-amyloid and anti-Iba1 antibodies were used. 

The step-through latency in the retention test in ELF-EMF exposure groups (100500 & 2000 µT) was significantly greater than the control group (P<0.05). Furthermore, the frequency of the entries into the open arms in ELF-EMF exposure groups (especially 2000 µT) decreased than the control group (P<0.05). No Aβ depositions were detected in the hippocampus of different groups. An increase in microglia numbers in the 100, 500, and 2000 µT groups was observed compared to the control and one µT group.

Exposure to ELF-EMF had an anxiogenic effect on rats, promoted memory, and induced oxidative stress. No Aβ depositions were detected in the brain. Moreover, the positive impact of ELF-EMF was observed on the microglia population in the brain.

Magnetic field is one of the effective and non-invasive modalities on biology and angiogenesis. Studies on the effects of magnetic fields on angiogenesis showed that the shape of the magnetic field could potentially affect angiogenesis. Therefore, this study aimed to control the frequency, intensity, and duration of exposure of magnetic field while investigating the effect of the shape of the magnetic field on the viability of Human Umbilical Vein Endothelial Cells (HUVECs).

The HUVECs were exposed to various shapes of 50 and 60 Hz magnetic fields with intensities of 0.5 and 1 mT in acute and chronic exposure regimes. The viability of HUVECs was assessed via MTT assay.

Results showed that the sin type 50 and 60 Hz magnetic fields are more effective in decreasing the viability. The rectified 100 and 120 Hz with 1 and 0.5 mT could increase and decrease the viability compared with 50 and 60 Hz, respectively.

It can be concluded that the shape of the magnetic field can be an effective factor in biology and must be controlled to have a reliable response.

Over the last decades, there has been an increasing trend in using cell phones which are exposing us to Radio-Frequency (RF) and Extremely Low Frequency (ELF) magnetic fields with various known and unknown biological effects. This protective study aimed to investigate the impact of environmental 217 Hz (as an ELF) magnetic fields generated by mobile phones on angiogenesis as an essential factor in tumor growth, in vitro and in vivo.
Magnetic fields with amplitudes of 0.5, 6, 22, 44, 65 & 159 µT were exposed on Human umbilical vein endothelial cells (HUVECs) and proliferation and viability of cells were measured. 3D angiogenesis assay was done by culturing HUVEC-covered microbeads in collagen gel and counting the number of sprouting micro-vessels per microbead. The percent of CD31 positive areas in breast tumor tissues of mice was assessed in the in vivo study.
Results showed that some of the applied amplitudes could increase proliferation as well as the viability of HUVECs. Furthermore, 22 and 44 µT magnetic fields could significantly increase the angiogenesis of breast tumors in the mouse.
There is a promoting effect from ELF magnetic fields generated by cell phones on the angiogenesis of tumors. It will be helpful if we recommend that cancer patients not to be exposed to cell phones.

 In recent years, the relationship between cancer cells and electromagnetic radiation has received much attention.

 The present study aimed to evaluate the effects of different intensities of electromagnetic fields on gastric cancer cell lines (AGS).

 After preparing AGS and Hu02 (normal) cell lines, they were exposed to magnetic flux densities of 0.25, 0.5, 1, and 2 millitesla (mT) for 18 h. The cell viability was studied by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The expression levels of hes1 and hsa-circ-0068530 RNAs were studied by the quantitative Real-time-PCR technique.

 The inhibition of gastric cancer cell line growth was observed under the influence of electromagnetic fields at different intensities. However, they did not affect the viability of normal cells. A sharp increase in the expression of hes1 and hsa-circ-0068530 genes was observed in normal cells exposed to 2 mT electromagnetic fields.

 In general, it can be concluded that the effect of electromagnetic fields on gastric cancer cells depends on their intensity. Magnetic flux densities of 0.25 and 0.5 mT had anti-cancer effects and magnetic flux density of 2 mT showed carcinogenic effects.

Ischemic stroke is considered as the second leading cause of death in the world and yet one of the causes of disability in adults. The present study aimed to evaluate the effects of iron oxide nanoparticles and the magnetic field on neural stem cells proliferation after ischemia/reperfusion in the rat model. This experimental study was conducted on a total of 50 male Wistar rats aged 6-7 weeks and weight of 220-250 g weight, which were divided into sham (i.e., ischemia-reperfusion model), control, iron oxide nanoparticles treated-, magnetic field exposed-, and simultaneously iron oxide nanoparticles and magnetic field exposed- groups. The brain ischemia/reperfusion was performed for 20 minutes by blocking the animal carotid arteries. In addition, neural stem cell proliferation was evaluated in the hippocampus of the 5 groups after 4 days by bromodeoxyuridine (BrdU) staining method. Then, the expression of Ki67 gene involved in the cell proliferation was quantitatively studied among the 5 groups by the quantitative real-time polymerase chain reaction (qRT-PCR). The results of BrdU staining revealed that iron oxide nanoparticles and the magnetic field separately increased cell proliferation after ischemia/reperfusion after 4 days in the hippocampus. However, simultaneous treatment with nanoparticles and magnetic field failed to show a significant difference compared to the sham group for 4 days. Conversely, the expression of Ki67 gene increased significantly in the group treated with iron oxide nanoparticles or the group exposed to magnetic field compared to the ischemia-reperfusion model. In general, iron oxide nanoparticles and magnetic field can separately be regarded as 2 effective methods for increasing the neural stem cell proliferation after ischemia/reperfusion.

With the development of science and technology, microwave has been used in many fields such as industry, military, medicine and communication. People are living in a lapped and dynamic electromagnetic environment. Concerns about potential hazards of microwave are getting increasing attentions. The single biological effects of microwave were widely discussed which was considered harmful. Relevant safety standards had been formulated and applied. However, the real environment was more complex. Microwave was not the only factor that organisms might be affected. Other physical or chemical factors, such as ionizing radiation (IR), ultraviolet (UV), magnetic field and chemical drugs, often existed with the microwave radiation. Even the microwave itself could create combined exposure situation, because the environment consisted different frequency microwaves. Nuclear weapons and high-power radar could produce microwave and ionizing radiation. The ultraviolet ray and magnetic field generated by the instrument's operation could act on the human bodies along with the microwaves. The combination of radiofrequency therapy and chemotherapeutic agents was also commonly used in cancer therapy. Therefore, the combined biological effects of microwaves and other physical or chemical factors were very important. This review had covered the original articles in this aspect. In order to better understand the combined biological effects, the comparative studies of different frequency microwaves were also included. Differences in biological effects were found among different frequency microwaves, and the combined biological effects contained both hazards and benefits. Findings in combined biological effects were very practical for rational uses of microwave technologies.

Electrification of transport systems currently deserves top priority in Iran. Such systems generate a magnetic field in static or extremely low frequency ranges. Therefore, train drivers may be exposed to these fields occupationally.
The current study aimed to measure the intensity of static magnetic field (SMF) and extremely low frequency magnetic fields (ELF-MF) in the subway trains of Tehran City in different train types and situations to show drivers’ exposure to SMF and ELF-MF.
Two AC and DC trains were randomly selected from lines 1 and 2, one AC train from line 4, and two ACi trains from line 5. The SMF and ELF-MF levels were measured based on BS EN 50500:2008 and recommendations in other studies using TES-1394 (ELF-MF meter) and HI-3550 (SMF meter). Ceiling values of ELF-MF and SMF were used for assessment of train driver’s exposure. One-way ANOVA, with Tukey post hoc test, and independent sample T-test were used for data analysis.
Maximum SMF and ELF-MF exposures were 0.52 mT (at DC trains- in trip situation) and 7.90 µT (at ACi trains- in trip situation), respectively, and the minimum exposures to SMF and ELF-MF were measured among the drivers of ACi ( As the obtained results suggest, in none of the situations, exposure of train drivers to ELF-MF and SMF exceeded the threshold limits recommended by ACGIH. However, the effects of these fields should not be ignored because different studies have reported adverse health consequences of these fields.