Effect of long-term power frequency electromagnetic field exposure on proliferation and apoptosis of SRA01/04 cells / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the effect of long-term power frequency electromagnetic field (50 Hz) exposure on the proliferation and apoptosis of human lens epithelial cells (SRA01/04 cells).</p><p><b>METHODS</b>SRA01/04 cells in the exponential growth phase were exposed or sham-exposed to power frequency electromagnetic field (50 Hz, 2.3 mT) for 2 hours per day, 5 days every week. After 11 weeks of exposure, the cells were collected; the cell morphology was observed under a microscope, the cell viability was measured by MTT assay, the cell cycle and apoptosis were examined by flow cytometry, and the protein expression levels of cyclin D and proliferating cell nuclear antigen (PCNA) were determined by western blot.</p><p><b>RESULTS</b>Compared with the sham-exposed SRA01/04 cells, most exposed cells became rounded and more stereoscopic, and heterochromatin gathered near the nuclear membrane in some exposed cells. The MTT assay showed that the viability of exposed cells was significantly increased compared with that of the sham-exposed cells (P < 0.05). Long-term power frequency electromagnetic field exposure led to significantly increased number of cells in S phase (P < 0.05), and the proliferation index was significantly higher in the exposed cells than in the sham-exposed cells (P < 0.05). There was no significant difference in apoptotic rate between the exposed cells and sham-exposed cells (P > 0.05). The exposed cells had significantly higher protein expression levels of cyclin D and PCNA than the sham-exposed cells (P < 0.05).</p><p><b>CONCLUSION</b>Long-term power frequency electromagnetic field exposure can promote cellular proliferation and change cell cycle in SRA01/04 cells, but it has no marked effect on the apoptosis of SRA01/04 cells.</p>

Detrimental effect of electromagnetic pulse exposure on permeability of in vitro blood-brain-barrier model / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study the effect of electromagnetic pulse (EMP) exposure on permeability of in vitro blood-brain-barrier (BBB) model.</p><p><b>METHODS</b>An in vitro BBB model, established by co-culturing brain microvascular endothelial cells (BMVEC) and astroglial cells (AC) isolated from rat brain, was exposed to EMP at 100 kV/m and 400 kV/m, respectively. Permeability of the model was assayed by measuring the transendothelial electrical resistance (TEER) and the horseradish peroxidase (HRP) transmission at different time points. Levels of BBB tight junction-related proteins were measured at 0, 1, 2, 4, 8, 12, 16, 20, 24 h after EMP exposure by Western blotting.</p><p><b>RESULTS</b>The TEER level was lower in BBB model group than in control group at 12 h after EMP, exposure which returned to its normal level at 24 h. The 24 h recovery process was triphasic and biphasic respectively after EMP exposure at 100 kV/m and 400 kV/m. Following exposure to 400 kV/m EMP, the HRP permeability increased at 1-12 h and returned to its normal level at 24 h. Western blotting showed that the claudin-5 and ZO-1 protein levels were changed after EMP exposure.</p><p><b>CONCLUSION</b>EMP exposure at 100 kV/m and 400 kV/m can increase the permeability of in vitro BBB model and BBB tight junction-related proteins such as ZO-1 and claudin-5 may change EMP-induced BBB permeability.</p>

Effects of electromagnetic pulse exposure on the morphological change and excretion function of BV-2 cells and possible mechanism / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of electromagnetic pulse (EMP) exposure on the morphological change and excretion functions of mouse microglia (BV-2) cells and possible mechanism.</p><p><b>METHODS</b>BV-2 cells were divided into two groups: the group exposed to EMP at 200 kV/m for 200 pulses and sham exposure group. At 1, 6, 12 and 24 hour after exposure the cells and culture supernatant were collected. Cellular morphological change was observed under invert microscope, the levels of TNF-α, IL-1β and IL-10 in culture supernatant were determined by enzyme-linked immunosorbent assay (ELISA), nitric oxide (NO) and reactive oxygen species (ROS) were detected by nitrate reductase method and DCFH-DA probe, respectively. The protein and phosphorylation levels of ERK, JNK and p38 were measured by Western Blot method. After the cells pre-treated with the inhibitor of p38 (SB203580) were exposed to EMP, the levels of NO and ROS in culture supernatant were detected.</p><p><b>RESULTS</b>It was found that the large ameboid shape appeared in some microglia cells exposed to EMP for 1, 6 and 12 h. Moreover, the number of microglia cells with ameboid shape increased significantly at 1 h, 6 h and 12 h after EMP exposure compared with sham group (P < 0.05). The levels of cytokines, such as TNF-α, IL-1β and IL-10, in culture supernatant did not change obviously after EMP exposure. The levels of NO and ROS increased significantly at 1h after EMP exposure, reached the peak at 6 h, began to recover at 12 h and recovered to sham group level at 24 h (P < 0.05). Western blot results showed that the protein and protein phosphorylation levels of ERK and JNK did not change significantly after EMP exposure, however, the protein and protein phosphorylation levels of p38 increased obviously at 1 h and 6 h after EMP exposure, compared with sham group (P < 0.05). In addition, the pretreatment of p38 inhibitor (SB203580) significantly decreased NO and ROS production induced by EMP.</p><p><b>CONCLUSION</b>EMP exposure may activate microglia cells and promote the production of NO and ROS in mouse microglia cells, and p38 pathway is involved in this process.</p>

Altered expression of matrix metalloproteinases and tight junction proteins in rats following PEMF-induced BBB permeability change / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate the expression of occludin, ZO-1, MMP-2, and MMP-9 in cerebral microvasculature following Pulse Electromagnetic Field (PEMF) induced BBB permeability change.</p><p><b>METHODS</b>Sprague-Dawley rats were randomized into PEMF and sham exposed groups (n = 8). After exposure to PEMF at 0.5, 1, 3, 6, and 12 h, BBB permeability was measured by Evans-Blue extravasation. The expression of occludin, ZO-1, MMP-2, and MMP-9 were detected by real-time quantitative reverse transcriptase PCR and western blotting. MMP-2 and MMP-9 activity were detected by EnzChek gelatinase assay.</p><p><b>RESULTS</b>Compared with the sham group, PEMF exposure led to increased permeability of the BBB to EB, which was prolonged after exposure. BBB permeability became progressively more severe, and recovered at 6 h. The gene and protein expression of occludin and ZO-1 were significantly decreased, while MMP-2 and MMP-9 expression were significantly increased after exposure to PEMF. All levels of expression recovered 12 h following PEMF.</p><p><b>CONCLUSION</b>Changes to BBB permeability were related to the alteration expression of tight junction proteins and matrix metalloproteinase after exposure to PEMF.</p>

Effects of electromagnetic pulse on blood-brain barrier permeability and tight junction proteins in rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effect of electromagnetic pulse (EMP) on the permeability of blood-brain barrier, tight junction (TJ)-associated protein expression and localization in rats.</p><p><b>METHODS</b>66 male SD rats, weighing (200 approximately 250) g, were sham or whole-body exposed to EMP at 200 kV/m for 200 pulses. The repetition rate was 1 Hz. The permeability of the blood-brain barrier in rats was assessed by albumin immunohistochemistry. The expression of typical tight junction protein ZO-1 and occludin in both cerebral cortex homogenate and cerebral cortex microvessel homogenate was analyzed by the Western blotting and the distribution of ZO-1 and occludin was examined by immunofluorescence microscopy.</p><p><b>RESULTS</b>In the sham exposure rats, no brain capillaries showed albumin leakage, at 0.5 h after 200 kV/m EMP exposure for 200 pulses; a few brain capillaries with extravasated serum albumin was found, with the time extended, the number of brain capillaries with extravasated serum albumin increased, and reached the peak at 3 h, then began to recover at 6 h. In addition, no change in the distribution of the occludin was found after EMP exposure. Total occludin expression had no significant change compared with the control. However, the expression level of ZO-1 significantly decreased at 1 h and 3 h after EMP exposure in both cerebral cortex homogenate and cerebral cortex microvessel homogenate. Furthermore, immunofluorescence studies also showed alterations in ZO-1 protein localization in cerebral cortex microvessel.</p><p><b>CONCLUSION</b>The EMP exposure (200 kV/m, 200 pulses) could increase blood-brain barrier permeability in rat, and this change is associated with specific alterations in tight junction protein ZO-1.</p>

Effect of electromagnetic pulse exposure on brain micro vascular permeability in rats / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To observe the effect of electromagnetic pulse (EMP) exposure on cerebral micro vascular permeability in rats.</p><p><b>METHODS</b>The whole-body of male Sprague-Dawley rats were exposed or sham exposed to 200 pulses or 400 pulses (1 Hz) of EMP at 200 kV/m. At 0.5, 1, 3, 6, and 12 h after EMP exposure, the permeability of cerebral micro vascular was detected by transmission electron microscopy and immunohistochemistry using lanthanum nitrate and endogenous albumin as vascular tracers, respectively.</p><p><b>RESULTS</b>The lanthanum nitrate tracer was limited to the micro vascular lumen with no lanthanum nitrate or albumin tracer extravasation in control rat brain. After EMP exposure, the lanthanum nitrate ions reached the tight junction, basal lamina and pericapillary tissue. Similarly, the albumin immunopositive staining was identified in pericapillary tissue. The changes in brain micro vascular permeability were transient, the leakage of micro vascular vessels appeared at 1 h, and reached its peak at 3 h, and nearly recovered at 12 h, after EMP exposure. In addition, the leakage of micro vascular was more obvious after exposure of EMP at 400 pulses than after exposure of EMP at 200 pulses.</p><p><b>CONCLUSION</b>Exposure to 200 and 400 pulses (1 Hz) of EMP at 200 kV/m can increase cerebral micro vascular permeability in rats, which is recoverable.</p>

Comparison of Hsps expression after radio-frequency field exposure in three human glioma cell lines / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate and compare the effect of radio-frequency (RF) field exposure on expression of heat shock proteins (Hsps) in three human glioma cell lines (MO54, A172, and T98).</p><p><b>METHODS</b>Cells were exposed to sham or 1950 MHz continuous-wave for 1 h. Specific absorption rates (SARs) were 1 and 10 W/kg. Localization and expression of Hsp27 and phosphorylated Hsp27 ((78) Ser) (p-Hsp27) were examined by immunocytochemistry. Expression levels of Hsp27, p-Hs27, and Hsp70 were determined by Western blotting.</p><p><b>RESULTS</b>The Hsp27 was primarily located within the cytoplasm, p-Hsp27 in both cytoplasm and nuclei of MO54, A172, and T98 cells. RF field exposure did not affect the distribution or expression of Hsp27. In addition, Western blotting showed no significant differences in protein expression of Hsp27 or Hsp70 between sham- and RF field-exposed cells at a SAR of 1 W/kg and 10 W/kg for 1 h in three cells lines. Exposure to RF field at a SAR of 10 W/kg for 1 h slightly decreased the protein level of phosphorylated Hsp27 in MO54 cells.</p><p><b>CONCLUSION</b>The 1950 MHz RF field has only little or no apparent effect on Hsp70 and Hsp27 expression in MO54, A172, and T98 cells.</p>

Effects of electromagnetic pulse on bone metabolism of mice in vivo / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study the effects of electromagnetic pulse (EMP) on bone metabolism of mice in vivo.</p><p><b>METHODS</b>Twenty-four male BALB/c mice were divided into a control group and 2 experimental groups (n=8). The whole-body of mice in experimental groups were exposed to 50 kV/m and 400kV/m EMP, 400 pulses daily for 7 consecutive days at 2 seconds intervals. Alkaline phosphotase (ALP) activity, serum calcium concentration and osteocalcin level and trabecular bone volume (BV/TV, %) were measured immediately after EMP exposure by biochemical, ELISA and morphological methods.</p><p><b>RESULTS</b>The ALP activity, serum calcium concentration and osteocalcin level and BV/TV in experimental groups remained unchanged after EMP exposure. Conclusion Under our experimental conditions, EMP exposure cannot affect bone metabolism of mice in vivo.</p>

Effect of electromagnetic pulse exposure on permeability of blood-testicle barrier in mice / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study the effect of electromagnetic pulse (EMP) exposure on the permeability of blood-testicle barrier (BTB) in mice.</p><p><b>METHODS</b>Adult male BALB/c mice were exposed to EMP at 200 kV/m for 200 pulses with 2 seconds interval. The mice were injected with 2% Evans Blue solution through caudal vein at different time points after exposure, and the permeability of BTB was monitored using a fluorescence microscope. The testis sample for the transmission electron microscopy was prepared at 2 h after EMP exposure. The permeability of BTB in mice was observed by using Evans Blue tracer and lanthanum nitrate tracer.</p><p><b>RESULTS</b>After exposure, cloudy Evans Blue was found in the testicle convoluted seminiferous tubule of mice. Lanthanum nitrate was observed not only between testicle spermatogonia near seminiferous tubule wall and sertoli cells, but also between sertoli cells and primary spermatocyte or secondary spermatocyte. In contrast, lanthanum nitrate in control group was only found in the testicle sertoli cells between seminiferous tubule and near seminiferous tubule wall.</p><p><b>CONCLUSION</b>EMP exposure could increase the permeability of BTB in the mice.</p>