Although some PAHs that are
Although some PAHs that are human carcinogens have been found in the sugarcane soot (Zamperlini et al., 1997), there are no data about cancer incidence among sugarcane workers. To the best of our knowledge, this is the first report of an evaluation of internal exposure, comparing the harvesting (when the sugarcane fields are burnt) and non-harvesting periods in sugarcane workers, with regard to polymorphisms of xenobiotic-metabolizing enzymes. Our study indicates that during the harvest period the sugarcane workers underwent intense exposure to genotoxic and mutagenic compounds. It also shows that sugarcane workers are significantly more exposed to PAH and genotoxic compounds during the harvesting time than during the non-harvesting time and than the control groups, although the difference between the urinary levels of 1-OHP was not significant in the exposed subjects bearing polymorphisms CYP1A1⁎2A, ⁎2B, ⁎4 and GSTP1. These findings indicate a potential risk for these workers, associated with respiratory diseases and/or lung cancer. Therefore, prevention strategies, such as the use of respiratory protection, are needed to reduce the inhalation and bifonazole of toxic compounds from burnt sugarcane fields.
Introduction The approval of new active pharmaceutical ingredients (APIs) requires investigation of their efficacy, safety and quality. In general, drug efficacy and safety is preclinically tested using animal models, which have several disadvantages over in vitro models and raises ethical concerns. Animal husbandry is time-consuming and cost-intensive and cannot be neglected. Furthermore, most experimental animals must be sacrificed for evaluation of the test results. In addition, poor standardization leads to high variability in the animal-based data. A major concern is to what extent the results of animal experiments are transferable to humans (Reichl et al., 2004, Reichl et al., 2005). Several studies have shown that the corneas of the commonly utilized animal models exhibit a morphology that is slightly different from that of the human cornea. For instance, the thickness of the epithelia and the tightness of their junctions in rabbit and porcine corneas are quite different, resulting in different permeation coefficients of APIs (Hahne and Reichl, 2011). Because of these disadvantages, several cell culture-based in vitro models have been developed with the aim of reducing and/or replacing animal testing. Based on the expected permeation route of APIs, in vitro models were created using appropriate cells. In the case of topically applied ophthalmic drugs, the human cornea provides the main permeation barrier (Burstein and Anderson, 1985) and should therefore be reproduced in tissue-engineering labs. Several cell culture models of the cornea have been developed (Pepić et al., 2014, Reichl et al., 2011). However, only a few of these models were tested for the permeation of ophthalmic drugs (Becker et al., 2008, Hahne and Reichl, 2011, Reichl et al., 2004, Reichl and Müller-Goymann, 2001, Tak et al., 2001, Tegtmeyer et al., 2004, Toropainen et al., 2001). To allow its widespread use as an alternative to animal models, a cornea model should be a three-dimensional (3D) construct produced using immortalized human cells that is highly similar to the human cornea and should be characterized as thoroughly as possible (Kölln and Reichl, 2015, Reichl et al., 2011). The most promising in vitro cornea model appears to be the Hemicornea construct, which was established and pre-validated by Hahne et al. (Hahne et al., 2012, Hahne and Reichl, 2011). This model, which contains immortalized human corneal cells (epithelial cells and keratocytes), has been evaluated with respect to the permeation coefficients of selected APIs (Hahne et al., 2012, Hahne and Reichl, 2011) and the expression of drug transporter proteins (Verstraelen and Reichl, 2013, Verstraelen and Reichl, 2014). However, the intraocular concentration of topically applied ophthalmic drugs does not depend only on the permeation barrier properties of the cornea and its levels of transporter proteins but may also be affected by its content of metabolic enzymes and the metabolic degradation of APIs during trancorneal passage. Although the Hemicornea construct contains cells of human origin, the Simian virus 40 (SV40)-immortalization process used to create them may have modified their protein expression patterns (Greco et al., 2010). Therefore, in a preliminary study, the Hemicornea construct was further characterized by investigating the expression of several phase I and phase II enzymes on the mRNA level relative to those of the human corneal epithelium (Kölln and Reichl, 2012). Briefly, 13 phase I and phase II enzymes were found to be expressed on the messenger RNA (mRNA) level in the Hemicornea construct with an expression pattern that was very similar to that of the in vivo human corneal epithelium. To characterize the metabolic properties of the Hemicornea construct, we decided to focus on the phase II enzyme family in the present study. These detoxification enzymes are subdivided into more than four groups but mainly consist of UDP-glucuronosyltransferases, sulfotransferases, N‐acetyltransferases and glutathione transferases, with the latter representing one of the major phase II enzyme families (Jancova et al., 2010).