Barboza L L, Campos V M A, Magalhães L A G, Paoli F, Fonseca A S
Departamento de Biofísica e Biometria, Instituto de Biologia Roberto Alcântara Gomes, Rio de Janeiro, RJ, BR.
Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, BR.
Braz J Med Biol Res. 2015 Oct;48(10):945-52. doi: 10.1590/1414-431X20154460. Epub 2015 Jul 28.
Semiconductor laser devices are readily available and practical radiation sources providing wavelength tenability and high monochromaticity. Low-intensity red and near-infrared lasers are considered safe for use in clinical applications. However, adverse effects can occur via free radical generation, and the biological effects of these lasers from unusually high fluences or high doses have not yet been evaluated. Here, we evaluated the survival, filamentation induction and morphology of Escherichia coli cells deficient in repair of oxidative DNA lesions when exposed to low-intensity red and infrared lasers at unusually high fluences. Cultures of wild-type (AB1157), endonuclease III-deficient (JW1625-1), and endonuclease IV-deficient (JW2146-1) E. coli, in exponential and stationary growth phases, were exposed to red and infrared lasers (0, 250, 500, and 1000 J/cm2) to evaluate their survival rates, filamentation phenotype induction and cell morphologies. The results showed that low-intensity red and infrared lasers at high fluences are lethal, induce a filamentation phenotype, and alter the morphology of the E. coli cells. Low-intensity red and infrared lasers have potential to induce adverse effects on cells, whether used at unusually high fluences, or at high doses. Hence, there is a need to reinforce the importance of accurate dosimetry in therapeutic protocols.
半导体激光器件是 readily available 且实用的辐射源，可提供波长可调性和高单色性。低强度红色和近红外激光被认为在临床应用中使用是安全的。然而，通过自由基生成可能会产生不良反应，并且这些激光在异常高的通量或高剂量下的生物学效应尚未得到评估。在此，我们评估了在异常高通量下暴露于低强度红色和红外激光时，缺乏氧化性 DNA 损伤修复能力的大肠杆菌细胞的存活率、丝状化诱导和形态。处于指数生长期和平稳生长期的野生型（AB1157）、内切酶 III 缺陷型（JW1625 - 1）和内切酶 IV 缺陷型（JW2146 - 1）大肠杆菌培养物，暴露于红色和红外激光（0、250、500 和 1000 J/cm²）下，以评估它们的存活率、丝状化表型诱导和细胞形态。结果表明，高通量的低强度红色和红外激光具有致死性，可诱导丝状化表型，并改变大肠杆菌细胞的形态。低强度红色和红外激光无论是在异常高通量下还是高剂量下使用，都有可能对细胞产生不利影响。因此，有必要在治疗方案中强化精确剂量测定的重要性。
