BACKGROUND: There are some studies proposing cell membrane may be one of target cell regions for electromagnetic biological effects. However, reports responsible for cellular membrane permeability and cellular biological effects after electromagnetic irradiation are few. OBJECTIVE: This study was designed to investigate the correlations of low-power millimeter wave irradiation to cellular membrane permeability and apoptosis of HL60.DESIGN: Controlled experiment.SETTING: Thus study was performed at the Medical Experimental Central Laboratory, Guangzhou General Hospital,Guangzhou Military Area Command of Chinese PLA between November 2006 and April 2007. MATERIALS: The human leukemic cell lines HL60 were kindly provided by Medical Experimental Center of Guangzhou Military Area Command of Chinese PLA and HD-413.2HPSG 100 millimeter wave irradiation generator was developed by Xi'an Hengda Microwave Technology Development Company, China. METHODS: HL60 cells were irradiated by millimeter wave at frequency of 41.32 GHz and mean power density of 2 mW/cm2, and divided into five groups according to the irradiation time (0, 15, 30, 45, 60 minutes groups).MAIN OUTCOME MEASURES: Lanthanum tracing was used to observe intracellular and extracellular lanthanum particles distribution and evaluate the change of cellular membrane permeability; ultrastructure and morphological characteristics of HL60 cells were observed through an transmission electron microscope; Quantitative analysis of apoptotic cells was performed by in situ marking method. RESULTS: In the 45 and 60 minutes groups, a small amount of lanthanum particles in the cytoplasm, swollen mitochondria, expanded rough endoplasmic reticulum, and obvious apoptosis were detected by ultrastructure observation. TUNEL staining showed, compared with the 0 minute control group, the apoptosis rate showed a trend of elevation in all the irradiation groups, particularly in the 45 and 60 minutes groups. CONCLUSION: Low-power millimeter wave irradiation on HL60 cells can lead to an increase in cellular membrane permeability of HL60, which may be one of the primary causes for promoting apoptosis and producing other biological effects.

During the electroporation cell membrane conductivity increases dramatically, so the analytical model for calculating the transmembrane voltage (TMV) induced on an unpermeabilized cell membrane in suspensions can not be used in this case. An analytical model for the TMV induced on a permeabilized cell membrane in suspensions exposed to a high voltage DC pulse field was built. First, a permeabilized cell was replaced by a sphere cell having the equivalent conductivity. Then the average field inside the permeabilized cell suspensions was calculated according to the effective medium theory. Finally, based on the analytical solution for the TMV on a single unpermeabilized cell, an analytical model for the TMV on a permeabilized cell in suspensions was derived. The model shows that the TMV depends on parameters such as the external electric field, critical angle of electroporation, cell radium, conductivity of the cytoplasm, membrane and external medium, cell arrangement and cell volume fraction.
Cell Membrane Permeability ; Electric Conductivity ; Electromagnetic Fields ; Electrophysiology ; Electroporation ; Humans ; Membrane Potentials ; Models, Biological ; Pulse

Objective: To study the effect of lentivirus-mediated microRNA (miR) -1246 RNA interference (RNAi) on biological characteristics and behaviors in cervical cancer cells as well as to identify the downstream signaling pathways affected. Methods: MiR-1246 specific cDNA was synthesized and cloned into the recombinant lentiviral vector (LV-miR-1246-inhibitor) . The SiHa cells were devided into three groups: no viral infection (negative control, NC) , infection with control virus (LV-NC) , and infection with miR-1246-inhibitor virus (LV-miR-1246-inhibitor) . The expression of the miR-1246 was detected by reverse transcription (RT) -PCR. Cell growth was analyzed by cell counting kit 8 (CCK-8) assay. The invasion was dectected by transwell matrige gel. Cell apoptosis was detected by flow cytometer. The growth of xenograft tumors was also investigated. Expression of thrombospondin-2 (THBS2) , matrix metalloproteinase (MMP) 2, 9 were also evaluated in the cells. Results: (1) The expression level of miR-1246 in SiHa cells (0.11±0.13) was significantly lower in group LV-miR-1246-inhibitor than those in the group LV-NC and the group NC (1.14±0.86 and 1.30±0.73, respectively; P<0.01) . (2) The proliferation of SiHa was also markedly suppressed in CCK-8 at 96 hours (P<0.01) . (3) The number of group LV-miR-1246-inhibitor was significantly less than those in the LV-NC and NC groups in transwell invasion assay (71±4, 162±5 and 188±5, respectively; P<0.01) . (4) The apoptosis rate of SiHa cells in the group LV-miR-1246-inhibitor [ (16.10±3.37) %] was significantly lower than those of group LV-NC and group NC [ (5.67±0.89) % and (1.78±0.08) %,P<0.01]. (5) The tumor volume in the nude mice group LV-miR-1246-inhibitor [ (287±59) mm³] was significantly lower than those in the LV-NC and NC groups [ (571±137) and (657±144) mm³, respectively; P<0.01]. (6) Compared with the LV-NC group and the NC group, THBS2 protein expression in the tumor tissue of the nude mice in the group LV-miR-1246-inhibitor was significantly increased (P<0.05) , while the expression levels of MMP-2 and MMP-9 protein were significantly decreased (P<0.01) . Conclusion These results suggest that miR-1246 functions during cervical cancer pathogenesis and tumor formation via the THBS2, MMP signaling pathway.

In the original publication the bands in Fig. 1J and Fig. 2B were not visible. The correct versions of Fig. 1J and Fig. 2B are provided in this correction.