Blackman C F, Blanchard J P, Benane S G, House D E, Elder J A
National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711-2055, USA.
Bioelectromagnetics. 1998;19(4):204-9. doi: 10.1002/(sici)1521-186x(1998)19:4<204::aid-bem2>3.0.co;2-5.
Previous work reported that nerve growth factor-stimulated neurite outgrowth in PC-12 cells could be altered by exposure to parallel alternating current (AC) and direct current (DC) magnetic fields under a variety of exposure conditions, producing results that are consistent with the predictions of the ion parametric resonance (IPR) model. The credibility of these results, considered extraordinary by some scientists, could be strengthened if the cell response were found to persist under alternate assay conditions. We replaced part of our standard assay procedure with a double blind procedure. This new procedure obscured 1) whether a particular set of dishes of cells was exposed or not, and 2) which individual dish was in which exposure system. The goal was to determine whether the previously observed responses of PC-12 cells to magnetic fields would be sufficiently robust to decode the imposed blinding, thereby removing any question of experimenter bias in reported results. We placed three coded dishes of cells in each of two otherwise identical exposure systems, one not energized and one energized to produce exposure conditions predicted to maximally suppress neurite outgrowth (Bdc of 36.6 microT, parallel 45 Hz AC of 23.8 microT rms). Each of the six dishes were recoded before assay to further obscure the exposure identity of any individual dish. The combined results of four distinct runs of these double blind experiments unequivocally demonstrated that 1) there was a clear, distinctive, repeatable consistency with the actual energization of the exposure systems and location of each dish, and with the predictions of the IPR model; 2) only the explicitly stated experimental variables influenced the experiment; and 3) the reported response of the cells was very improbably due to chance (P = .000024).
先前的研究报道，在各种暴露条件下，暴露于平行交变电流（AC）和直流（DC）磁场会改变神经生长因子刺激的PC-12细胞的神经突生长，产生的结果与离子参数共振（IPR）模型的预测一致。如果发现细胞反应在替代检测条件下持续存在，那么这些结果的可信度（一些科学家认为这些结果非同寻常）将会得到加强。我们用双盲程序取代了部分标准检测程序。这个新程序掩盖了1）一组特定的细胞培养皿是否被暴露，以及2）每个单独的培养皿位于哪个暴露系统中。目的是确定先前观察到的PC-12细胞对磁场的反应是否足够稳健，以解开施加的盲法，从而消除报告结果中实验者偏差的任何疑问。我们在两个其他方面相同的暴露系统中，每个系统放置三个编码的细胞培养皿，一个不通电，一个通电以产生预计能最大程度抑制神经突生长的暴露条件（直流磁场强度为36.6微特斯拉，平行45赫兹交流磁场有效值为23.8微特斯拉）。在检测之前，对六个培养皿中的每一个重新编码，以进一步模糊任何单个培养皿的暴露身份。这些双盲实验的四次不同运行的综合结果明确表明：1）暴露系统的实际通电情况和每个培养皿的位置，以及与IPR模型的预测之间存在明显、独特、可重复的一致性；2）只有明确说明的实验变量影响实验；3）所报道的细胞反应极不可能是偶然的（P = 0.000024）。
