Belma Kocer-Gumusel

Genotoxicity of phthalates

Abstract Many of the environmental, occupational and industrial chemicals are able to generate reactive oxygen species (ROS) and cause oxidative stress. ROS may lead to genotoxicity, which is suggested to contribute to the pathophysiology of many human diseases, including inflammatory diseases and cancer. Phthalates are ubiquitous environmental chemicals and are well-known peroxisome proliferators (PPs) and endocrine disruptors. Several in vivo and in vitro studies have been conducted concerning the carcinogenic and mutagenic effects of phthalates. Di(2-ethylhexyl)-phthalate (DEHP) and several other phthalates are shown to be hepatocarcinogenic in rodents. The underlying factor in the hepatocarcinogenesis is suggested to be their ability to generate ROS and cause genotoxicity. Several methods, including chromosomal aberration test, Ames test, micronucleus assay and hypoxanthine guanine phosphoribosyl transferase (HPRT) mutation test and Comet assay, have been used to determine genotoxic properties of phthalates. Comet assay has been an important tool in the measurement of the genotoxic potential of many chemicals, including phthalates. In this review, we will mainly focus on the studies, which were conducted on the DNA damage caused by different phthalate esters and protection studies against the genotoxicity of these chemicals.

The evaluation of possible role of endocrine disruptors in central and peripheral precocious puberty

Abstract Exposure to environmental chemicals can affect genetic and epigenetic molecular pathways and may cause altered growth and development. Among those exposures, endocrine-disrupting chemicals (EDCs) are of particular concern as humans are abundantly exposed to these chemicals by various means in every period of life. Several well-known environmental chemicals, including phthalates and bisphenol A (BPA), are classified as EDCs. These EDCs are suggested to play roles in early onset of puberty in girls. The aim of this study is to determine plasma phthalate (di(2-ethylhexyl)phthalate [DEHP] and its main metabolite mono(2-ethylhexyl)phthalate [MEHP]) and urinary BPA levels in girls with idiopathic central precocious puberty (CPP) and peripheral precocious puberty (PPP). This study was performed on newly diagnosed idiopathic central precocious puberty (CPP) patients (n = 42) and peripheral precocious puberty (PPP) (n = 42) patients, who were admitted to Keçiören Training and Research Hospital, Clinic of Pediatric Endocrinology between August 2012 and –July 2013. Nonobese healthy girls (n = 50) were used as the control group. Urinary BPA levels were not statistically different in control, PPP and CPP groups (medians 10.91, 10.63 and 10.15 μg/g creatinine, respectively; p > 0.05). Plasma DEHP levels were significantly higher in PPP group when compared to control. Plasma MEHP levels were not significantly different in control and PPP groups (p > 0.05). However, in CPP group, both plasma DEHP and MEHP levels were significantly higher than control and PPP groups. This study showed that phthalates might play a role in the occurence of CPP in girls.

The effects of di(2-ethylhexyl) phthalate and/or selenium on trace element levels in different organs of rats.

Di(2-ethylhexyl)phthalate (DEHP), a widely used plasticizer for synthetic polymers, is known to have endocrine disruptive potential, reproductive toxicity, and induces hepatic carcinogenesis in rodents. Selenium (Se) is a component of several selenoenzymes which are essential for cellular antioxidant defense and for the functions of mammalian reproductive system. The present study was designed to investigate the effects of DEHP exposure on trace element distribution in liver, testis, and kidney tissues and plasma of Se-deficient and Se-supplemented rats. Se deficiency was produced by feeding 3-week old Sprague-Dawley rats with ≤0.05mg Se/kg diet for 5 weeks, and supplementation group were on 1mg Se/kg diet. DEHP treated groups received 1000mg/kg dose by gavage during the last 10 days of feeding period. Se, zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn) levels were measured by inductively coupled plasma mass spectrometry (ICP-MS). Se supplementation caused significant increases in hepatic, renal, and testicular Se levels. With DEHP exposure, plasma Se and Zn, kidney Se, Cu and Mn levels were significantly decreased. Besides, liver Fe decreased markedly in all the DEHP-treated groups. Liver and kidney Mn levels decreased significantly in DEHP/SeD group compared to both DEHP and SeD groups. These results showed the potential of DEHP exposure and/or different Se status to modify the distribution pattern of essential trace elements in various tissues, the importance of which needs to be further evaluated.

Cytoplasmic and nuclear toxicity of 3,5-dimethylaminophenol and potential protection by selenocompounds

Most common alkylanilines in the environment are 2,6-dimethylaniline (2,6-DMA), 3,5-dimethylaniline (3,5-DMA), and 3-ethylaniline (3-EA). 3,5-Dimethylaminophenol (3,5-DMAP), a metabolite of 3,5-DMA, is of particular interest, as it is potentially genotoxic. Supplementation with organic or inorganic forms of selenium (Se) may reduce toxicity following exposure to a wide variety of environmental chemicals. This study was designed to evaluate the protective effects of sodium selenite (SS) and selenomethionine (SM) at varying time points of supplementation (24 h and 72 h) against the cytotoxicity, reactive oxygen species (ROS) production, and genotoxicity of 3,5-DMAP in CHO AS52 cells. 3,5-DMAP caused dose-dependent increase of cytotoxicity, ROS production and genotoxicity, and generated free radicals in the nuclei. Thioredoxin reductase (TrxR), catalase and glutathione reductase activities, and glutathione levels were significantly lower while lipid peroxidation and protein oxidation levels were higher after 3,5-DMAP treatment in both cytoplasm and the nucleus vs. control. After 24 h, both SS and SM provided protection in antioxidant/oxidant status of the 3,5-DMAP-treated cells; however other than supplying higher glutathione peroxidase and TrxR activities, 72 h supplementation did not provide advanced improvement. Selenocompounds may be beneficial against cytotoxic and genotoxic potential of 3,5-DMAP and might protect both nucleus and cytoplasm following exposure to alkylanilines.

Oxidant and antioxidant status in neonatal proven and clinical sepsis according to selenium status

Selenium is a trace element required for the functioning of the immune system. Neonatal sepsis is a serious condition leading to morbidity and mortality in neonates worldwide. The purpose of this study was to measure selenium and plasma selenoprotein P (SePP), selenoenzyme activity, and alterations in oxidant/antioxidant status with immune biomarkers in neonates with clinical (n = 27) and proven neonatal sepsis (n = 25).

Urinary bisphenol A levels in Turkish girls with premature thelarche

There is a growing concern over the timing of pubertal breast development and its possible association with exposure to endocrine disrupting chemicals (EDCs), such as bisphenol A (BPA). BPA is abundantly used to harden plastics. The aim of this study was to investigate the relation between premature thelarche (PT) and BPA by comparing the urinary BPA levels of PT girls with those of healthy subjects. Twenty-five newly diagnosed nonobese PT subjects (aged 4–8 years) who were admitted to the Pediatric Endocrinology Department at Akdeniz University were recruited. The control group composed of 25 age-matched girls without PT and other endocrine disorders. Urinary BPA levels were measured by high pressure liquid chromatography. The median urinary concentrations of BPA were found to be significantly higher in the PT group compared to the healthy control group (3.2 vs. 1.62 μg/g creatinine, p < 0.05). We observed a weak positive correlation between uterus volume and urinary BPA levels. There was a weak correlation between estradiol and urinary BPA levels (r = 0.166; p = 0.37); and luteinizing hormone and urinary BPA levels (r = 0.291; p = 0.08) of PT girls. Our results suggest that exposure to BPA might be one of the underlying factors of early breast development in prepubertal girls and EDCs may be considered as one of the etiological factors in the development of PT.

Impaired antioxidant enzyme functions with increased lipid peroxidation in epithelial ovarian cancer

We aimed to identify the possible role of oxidant–antioxidant status in epithelial ovarian cancer (EOC) by measuring (a) antioxidant enzyme (AOE) activities [total superoxide dismutase (SODtotal), manganese‐SOD (Mn‐SOD), copper,zinc‐SOD (Cu,Zn‐SOD), catalase (CAT) and glutathione peroxidase (GPx1)], (b) Mn‐SOD protein expression, (c) lipid peroxidation markers [malondialdehyde (MDA), 8‐epi‐prostaglandin‐F2α (8‐epi‐PGF2α)] and by evaluating the possible correlations between tumor biomarkers, reproductive hormone levels and all measured parameters, comprehensively. The data obtained from the patients with EOC (M, n = 26) evaluated according to the histopathological/clinical characteristics of tumors and compared with data of healthy controls [Ctissue (C1) and Cblood/urine (C2), n = 30, respectively). Significantly, low activities of tumor SODtotal (52%), Mn‐SOD (42%), Cu,Zn‐SOD (55%); high activities of tumor and erythrocyte CAT (66%, 33% respectively) and tumor GPx1 (60%); high levels of tumor Mn‐SOD protein expression; tumor MDA (193%) and urinary 8‐epi‐PGF2α (179%) were observed in serous EOC tumors (M1, n = 18) compared with controls (P < 0.05). However, higher levels of tumor MDA, Mn‐SOD protein expression and urinary 8‐epi‐PGF2α were observed along with lower tumor CAT activity in poorly differentiated or undifferentiated (grade 3, G 3) versus well or moderately well differentiated (grade 1‐2, G 1‐2) serous EOC tumors. Obtained data indicate the presence of a severe redox imbalance in EOC and draw attention to the criticial role of AOEs in the pathogenesis of the disease.

Environmental Effects of Endocrine-Disrupting Chemicals: A Special Focus on Phthalates and Bisphenol A

Several environmental chemicals are classified as endocrine-disrupting chemicals (EDCs). Many of them have an impact on reproductive functions and sex hormones because of their estrogenic and/or antiandrogenic properties. Phthalates and bisphe‐ nol A (BPA) are two well-known EDCs. They are abundant in the environment. Phthalates are usually classified as antiandrogens, whereas BPA is considered as estrogen-like EDC and xenoestrogen. Other than their endocrine-disrupting effects, these two chemicals are also known to have genotoxic and epigenetic effects. Besides, they are hepatotoxic and have substantial effects on other organs/systems (thyroid, kidney, neuroendocrine system, immune system, etc.). In this chapter, we will mainly focus on the toxic effects of different phthalate esters and BPA by discussing their availability in the environment, mechanism and mode of actions, their biotransforma‐ tion and reproductive effects, and their effects on other systems (hepatic, renal, etc.). Besides, we discuss epidemiological studies that are conducted to reveal their effects on the reproductive and endocrine systems. This chapter provides the readers a compact piece of knowledge on these abundant substances and helps them to understand the action of these substances at the molecular and cellular levels.

Impact of selenium status on Aroclor 1254-induced DNA damage in sperm and different tissues of rats

Abstract Aroclor 1254 is a commercial mixture of polychlorinated biphenyls (PCBs), which are widespread environmental pollutants. It is used as non-flammable heat transfer agent and plasticizer. Animal studies have reported that Aroclor 1254 exerted toxic effects in different organs and systems. Although the evidences are limited, it seems reasonable that Aroclor 1254 may have a potential for similar adverse effects in humans. Selenium (Se) is a trace element and an important component of cellular antioxidant defense. This study was designed to investigate the effects of different Se status on the genotoxicity of Aroclor 1254 in sperm and different organs of Sprague-Dawley rats using Comet assay. Se deficiency (SeD) was generated by feeding 3-week old Sprague-Dawley rats with <0.05 Se mg/kg diet for 5 weeks. Se supplementation groups (SeS) were fed with 1 mg Se/kg diet. Aroclor 1254-treated rats received 10 mg/kg dose by gavage during the last 15 d of feeding period. SeD increased DNA damage in all of the organs as well as in lymphocytes and sperm. Aroclor 1254 treatment caused pronounced changes in liver, kidney and brain cells along with marked increases in lymphocytes and sperm. Se supplementation provided full or partial protection decreases in Aroclor 1254-induced DNA damage in sperm and all of tissues. Se deficiency aggravated the toxicity by increasing DNA damage caused by Aroclor 1254. Further studies should be performed to clarify the mechanism(s) underlying the protective role of Se status against Aroclor 1254 genotoxicity.

Evaluation of skin irritation potentials of different cosmetic products in Turkish market by reconstructed human epidermis model

Human skin is a protective barrier against the toxic effects of cosmetics. Marketing of cosmetic products with ingredients tested on animals was prohibited in 2013. Since then, safety evaluation of cosmetic products is performed by using alternative in vitro toxicity tests. In vitro 3-D reconstructed human epidermis (RhE) tissue models are now used to define skin irritation/corrosion potentials of cosmetic ingredients and end-products. The main aim of this study was to evaluate skin irritation potentials of topically used cosmetic end-products which were marketed in Turkey during 2015-2017, by using the EpiDerm in vitro 3D-human skin model. Sixty widely used cosmetic products were collected from different markets/cosmetic shops. Among hair care products, only one shampoo was found to be strong/severe skin irritant/possible corrosive while 22 shampoos were moderate skin irritant and 11 shampoos were moderate to mild skin irritant. Among 6 skin care products, one was found to be moderate to mild skin irritant. We can suggest that alternative in vitro tests should continuously be used to test both the ingredients and the final cosmetic formulations.