Oxidative DNA damage and repair in teratogenesis and neurodevelopmental deficits

Introducing the Role of Genotoxicity in Neurodegenerative Diseases and Neuropsychiatric Disorders

Decades of research have identified genetic and environmental factors involved in age-related neurodegenerative diseases and, to a lesser extent, neuropsychiatric disorders. Genomic instability, i.e., the loss of genome integrity, is a common feature among both neurodegenerative (mayo-trophic lateral sclerosis, Parkinson's disease, Alzheimer's disease) and psychiatric (schizophrenia, autism, bipolar depression) disorders. Genomic instability is associated with the accumulation of persistent DNA damage and the activation of DNA damage response (DDR) pathways, as well as pathologic neuronal cell loss or senescence. Typically, DDR signaling ensures that genomic and proteomic homeostasis are maintained in both dividing cells, including neural progenitors, and post-mitotic neurons. However, dysregulation of these protective responses, in part due to aging or environmental insults, contributes to the progressive development of neurodegenerative and/or psychiatric disorders. In this Special Issue, we introduce and highlight the overlap between neurodegenerative diseases and neuropsychiatric disorders, as well as the emerging clinical, genomic, and molecular evidence for the contributions of DNA damage and aberrant DNA repair. Our goal is to illuminate the importance of this subject to uncover possible treatment and prevention strategies for relevant devastating brain diseases.

Toxicokinetic analyses of naphthalene, fluorene, phenanthrene, and pyrene in humans after single oral administration

Polycyclic aromatic hydrocarbons (PAHs) are generated by incomplete combustion of organic matter. They have health effects in multiple organs and can cause lung, skin, and bladder cancers in humans. Although data regarding their toxicity is available, information on the absorption, distribution, metabolism, and excretion of PAHs in humans is very limited. In the present study, deuterium-labeled naphthalene (Nap), fluorene (Flu), phenanthrene (Phe), and pyrene (Pyr) were orally administered as a single dose (0.02-0.04 mg/kg) to eight healthy adults. Both serum and urine samples were monitored for 72 h after the exposure. Parent compounds and PAH metabolites (monohydroxy-PAHs; OH-PAHs) were measured by headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry and high-performance liquid chromatography-tandem mass spectrometry, respectively. Based on the time-concentration profiles in serum and urine, non-compartmental analysis was performed, and two-compartment models were constructed and validated for each PAH. Subsequently, all of the parent compounds were rapidly absorbed (T_max: 0.25 to 1.50 h) after oral administration and excreted in urine with a biological half-life (T_1/2) of 1.01 to 2.99 h. The fractional urinary excretion (F_ue) of OH-PAHs ranged from 0.07 % to 11.3 %; their T_1/2 values ranged from 3.4 to 11.0 h. The two-compartment models successfully described the toxicokinetic characteristics of each PAH and its metabolites. F_ue and the two-compartment models could be useful tools for exposure simulation or dose-reconstruction of PAHs. The results of this study will provide useful information for interpreting biomonitoring data of PAHs.

Genes Involved in DNA Repair and Mitophagy Protect Embryoid Bodies from the Toxic Effect of Methylmercury Chloride under Physioxia Conditions

The formation of embryoid bodies (EBs) from human pluripotent stem cells resembles the early stages of human embryo development, mimicking the organization of three germ layers. In our study, EBs were tested for their vulnerability to chronic exposure to low doses of MeHgCl (1 nM) under atmospheric (21%O₂) and physioxia (5%O₂) conditions. Significant differences were observed in the relative expression of genes associated with DNA repair and mitophagy between the tested oxygen conditions in nontreated EBs. When compared to physioxia conditions, the significant differences recorded in EBs cultured at 21% O₂ included: (1) lower expression of genes associated with DNA repair (ATM, OGG1, PARP1, POLG1) and mitophagy (PARK2); (2) higher level of mtDNA copy number; and (3) higher expression of the neuroectodermal gene (NES). Chronic exposure to a low dose of MeHgCl (1 nM) disrupted the development of EBs under both oxygen conditions. However, only EBs exposed to MeHgCl at 21% O₂ revealed downregulation of mtDNA copy number, increased oxidative DNA damage and DNA fragmentation, as well as disturbances in SOX17 (endoderm) and TBXT (mesoderm) genes expression. Our data revealed that physioxia conditions protected EBs genome integrity and their further differentiation.

Establishing the relationship between Polycyclic Aromatic Hydrocarbons (PAHs) exposure and male infertility: A systematic review

It has been demonstrated that human exposure to environmental chemicals may have sperm genotoxic potentiality. Among the different classes, Polycyclic Aromatic Hydrocarbons (PAHs) have been receiving attention in recent years due to reports of sperm geno-toxicity, a series of reproductive defects and male infertility. This review aims to substantiate the effects of PAHs exposure on male infertility, with focus on the sperm characteristics (count, concentration, volume, motility, DNA damage, and morphology). To this end, international databases such as Cochrane Library, PubMed, Web of Science, Embase Ovid, Scopus, and Google Scholar were used to conduct a systematic search for papers on the subject, based on PRISMA guidelines, published up to 24 March 2022. The Newcastle-Ottawa Scale was subsequently used to assess the quality of the studies. The results showed that there is a significant negative relationship between PAHs metabolites and sperm volume, concentration, motility, morphology, as well as an observed DNA degeneration. Also, the CYP1A1 genotype polymorphisms were considered as a representative of PAHs exposure to infertility; the review highlights that polymorphisms of this genotype were more common in the infertile people. In overall, this work provides a solid summary of the existing works correlating PAHs exposure and male infertility, which could impulse further protective measures and informative campaigns on users, workers, and general population.

An investigation of DNA damage and DNA repair in chemical carcinogenesis triggered by small-molecule xenobiotics and in cancer: Thirty years with the comet assay

In the present review we addressed the determination of DNA damage induced by small-molecule carcinogens, considered their persistence in DNA and mutagenicity in in vitro and in vivo systems over a period of 30 years. The review spans from the investigation of the role of DNA damage in the cascade of chemical carcinogenesis. In the nineties, this concept evolved into the biomonitoring studies comprising multiple biomarkers that not only reflected DNA/chromosomal damage, but also the potential of the organism for biotransformation/elimination of various xenobiotics. Since first years of the new millennium, dynamic system of DNA repair and host susceptibility factors started to appear in studies and a considerable knowledge has been accumulated on carcinogens and their role in carcinogenesis. It was understood that the final biological links bridging the arising DNA damage and cancer onset remain to be elucidated. In further years the community of scientists learnt that cancer is a multifactorial disease evolving over several decades of individual´s life. Moreover, DNA damage and DNA repair are inseparable players also in treatment of malignant diseases, but affect substantially other processes, such as degeneration. Functional monitoring of DNA repair pathways and DNA damage response may cast some light on above aspects. Very little is currently known about the relationship between telomere homeostasis and DNA damage formation and repair. DNA damage/repair in genomic and mitochondrial DNA and crosstalk between these two entities emerge as a new interesting topic.

Bibliometric analysis of global research on polycyclic aromatic hydrocarbons and health risk between 2002 and 2021

During the last 20 years, the association between polycyclic aromatic hydrocarbons (PAHs) and health risk has become one of the hotspots in the fields of public health and the environment. A bibliometric study of 1392 research articles retrieved from the Web of Science Core Collection (WoSCC) published between 2002 and 2021 was performed to give an in-depth statistical evaluation of research progress and future trends on PAHs and health risk (PHR). According to the findings, the annual output of significant scientific papers increased exponentially. China ranked first among the 86 nations in terms of the number of publications (NP), followed by the USA and India. Logistic regression analysis showed that there was a positive relationship between the second tertile of 180-day usage count (AOR = 1.62; 95% CI: 1.16-2.26) and increased odds of open access publishing after adjustment for the confounders, indicating that open access papers on PHR were more preferred over the preceding 6 months than non-open access articles. The most popular terms were "PAHs," "risk assessment," and "source identification." According to the bibliometric study, the research hotspots that require more exploration include identifying PAH sources in media such as soil, water, dust, and food and evaluating their linkages to health hazards using appropriate risk models. Understanding the environmental behavior, bioavailability, and health concerns of PAHs and their derivatives in various media is critical for environmental and public health protection. This paper provides an overview of current research status and future perspectives for PHR research.

DNA damage in preimplantation embryos and gametes: specification, clinical relevance and repair strategies

BACKGROUND

DNA damage is a hazard that affects all cells of the body. DNA-damage repair (DDR) mechanisms are in place to repair damage and restore cellular function, as are other damage-induced processes such as apoptosis, autophagy and senescence. The resilience of germ cells and embryos in response to DNA damage is less well studied compared with other cell types. Given that recent studies have described links between embryonic handling techniques and an increased likelihood of disease in post-natal life, an update is needed to summarize the sources of DNA damage in embryos and their capacity to repair it. In addition, numerous recent publications have detailed novel techniques for detecting and repairing DNA damage in embryos. This information is of interest to medical or scientific personnel who wish to obtain undamaged embryos for use in offspring generation by ART.

OBJECTIVE AND RATIONALE

This review aims to thoroughly discuss sources of DNA damage in male and female gametes and preimplantation embryos. Special consideration is given to current knowledge and limits in DNA damage detection and screening strategies. Finally, obstacles and future perspectives in clinical diagnosis and treatment (repair) of DNA damaged embryos are discussed.

SEARCH METHODS

Using PubMed and Google Scholar until May 2021, a comprehensive search for peer-reviewed original English-language articles was carried out using keywords relevant to the topic with no limits placed on time. Keywords included ‘DNA damage repair’, ‘gametes’, ‘sperm’, ‘oocyte’, ‘zygote’, ‘blastocyst’ and ‘embryo’. References from retrieved articles were also used to obtain additional articles. Literature on the sources and consequences of DNA damage on germ cells and embryos was also searched. Additional papers cited by primary references were included. Results from our own studies were included where relevant.

OUTCOMES

DNA damage in gametes and embryos can differ greatly based on the source and severity. This damage affects the development of the embryo and can lead to long-term health effects on offspring. DDR mechanisms can repair damage to a certain extent, but the factors that play a role in this process are numerous and altogether not well characterized. In this review, we describe the multifactorial origin of DNA damage in male and female gametes and in the embryo, and suggest screening strategies for the selection of healthy gametes and embryos. Furthermore, possible therapeutic solutions to decrease the frequency of DNA damaged gametes and embryos and eventually to repair DNA and increase mitochondrial quality in embryos before their implantation is discussed.

WIDER IMPLICATIONS

Understanding DNA damage in gametes and embryos is essential for the improvement of techniques that could enhance embryo implantation and pregnancy success. While our knowledge about DNA damage factors and regulatory mechanisms in cells has advanced greatly, the number of feasible practical techniques to avoid or repair damaged embryos remains scarce. Our intention is therefore to focus on strategies to obtain embryos with as little DNA damage as possible, which will impact reproductive biology research with particular significance for reproductive clinicians and embryologists.

High concentrations of aluminum in maternal serum and placental tissue are associated with increased risk for fetal neural tube defects

Aluminum (Al)¹ is ubiquitously present in the environment, and human exposure to Al is common. Al has been reported to be involved in various human diseases and adverse pregnancy outcomes, including neural tube defects (NTDs). This study aimed to examine the association between prenatal Al exposure and the risk for NTDs using Al concentrations in maternal serum and placental tissue. The subjects were recruited from six counties/cities in the Shanxi province of northern China from 2003 to 2016. Al concentrations in both types of specimens were assessed using inductively coupled plasma-mass spectrometry. In the maternal serum cohort (200 cases and 400 controls), compared to the lowest tertile concentration of Al, the highest Al tertile was associated with 2.42-fold (95% confidence interval, 1.23-4.87) increased risk after adjustment for confounding factors. In the placental tissue cohort (408 cases and 593 controls), the highest tertile of Al also tended to be associated with an elevated risk for NTDs [adjusted odds ratio, 1.60 (0.94-2.70)]. When analyzed by NTD subtypes, the highest Al tertile was associated with an increased risk for anencephaly in both cohorts after adjustment for confounders [odds ratio, 1.97 (1.15-3.48) in the maternal serum cohort; odds ratio, 4.75 (2.01-12.00) in the placental tissue cohort]. Taken together, using concentrations of Al in maternal serum and placental tissue as exposure markers, we found that prenatal exposure to higher levels of Al is a risk factor for fetal NTDs, especially for the anencephaly subtype.

Prevention of Teratogenesis in Pregnancies of Obese Rats by Vitamin E Supplementation

Congenital malformations are a common adverse outcome in pregnancies complicated by pregestational obesity, although the underlying mechanisms are still unrevealed. Our aim was to study the effect of oxidative stress in obesity-induced teratogenesis. Wistar rats were fed a high-fat diet for 13 weeks, with (OE group) or without (O group) vitamin E supplementation. Then, rats were mated and sacrificed at day 11.5 of gestation. Embryos from O dams presented a 25.9 ± 3.5% rate of malformations (vs. 8.7 ± 3.4% in C rats), which was reduced in the OE group (11.5 ± 2.3%). Pregestational obesity induced hepatic protein and DNA oxidation and a decline in antioxidant enzymes. Importantly, glutathione content was also decreased, limiting the availability of this antioxidant in the embryos. Vitamin E supplementation efficiently maintained glutathione levels in the obese mothers, which could be used in their embryos to prevent oxidation-induced malformations. To test the effect of decreasing glutathione levels alone in a cell culture model of neuroepithelium, murine embryonic stem cells (ESC) were induced to form neuronal precursors and glutathione synthesis was inhibited with the gamma–glutamylcysteine synthesis inhibitor, buthionine sulfoximine (BSO). BSO inhibited the expression of Pax3, a gene required for neural tube closure that is also inhibited by oxidative stress. Taken together, our data indicate that obesity causes malformations through the depletion of maternal glutathione, thereby decreasing glutathione-dependent free radical scavenging in embryos, which can be prevented by vitamin E supplementation.

Anesthesia for Nonobstetric Surgery in Pregnancy

Nonobstetric surgery during pregnancy occurs in 1% to 2% of pregnant women. Physiologic changes during pregnancy may have an impact when anesthesia is needed. Anesthetic agents commonly used during pregnancy are not associated with teratogenic effects in clinical doses. Surgery-related risks of miscarriage and prematurity need to be elucidated with well-designed studies. Recommended practices include individualized use of intraoperative fetal monitoring and multidisciplinary planning to address the timing and type of surgery, anesthetic technique, pain management, and thromboprophylaxis. Emergency procedures should be performed immediately and elective surgery should be deferred during pregnancy.

Exposure to fine particulate matter-bound polycyclic aromatic hydrocarbons, male semen quality, and reproductive hormones: The MARCHS study

Exposure to outdoor fine particulate matter (PM_2.5)-bound polycyclic aromatic hydrocarbons (PAHs) is linked to reproductive dysfunction. However, it is unclear which component of PAHs is responsible for the adverse outcomes. In the Male Reproductive Health in Chongqing College Students (MARHCS) cohort study, we measured the exposure levels of 16 PAHs by collecting air PM_2.5 particles and assessed eight PAHs metabolites from four parent PAHs, including naphthalene, fluorene, phenanthrene, and pyrene in urine samples. We investigated compositional profiles and variation characteristics for 16 PAHs in PM_2.5, and then assessed the association between PAHs exposure and semen routine parameters, sperm chromatin structure, and serum hormone levels in 1452 samples. The results showed that naphthalene (95% CI: -17.989, -8.101), chrysene (95% CI: -64.894, -47.575), benzo[a]anthracene (95% CI: -63.227, -45.936) and all the high molecular weight (HMW) PAHs in PM_2.5 were negatively associated with sperm normal morphology. Most of the low molecular weight (LMW) PAHs, such as acenaphthylene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, ∑LMW PAHs and ∑16 PAHs, were correlated with increased sperm motility (all corrected P < 0.05). On the other hand, sperm normal morphology was all negatively associated with urinary metabolites of ∑OH-Nap (95% CI: -5.611, -0.536), ∑OH-Phe (95% CI: -5.741, -0.957), and ∑OH-PAHs (95% CI: -5.274, -0.361). Urinary concentrations of ∑OH-PAHs were found to be negatively associated with sperm high DNA stainability (HDS) (P = 0.023), while ∑OH-Phe were negatively associated with serum testosterone level and sperm HDS (P = 0.004). Spearman correlation analysis showed that except for the urinary OH-Nap metabolites, the rest of the urinary OH-PAHs metabolites were negatively correlated with their parent PAHs in air. The results of this study suggest that various PAHs' components may affect reproductive parameters differently. Inhalation of PAHs in air, especially HMW PAHs, may be a potential risk factor for male reproductive health.

A review of human and animals exposure to polycyclic aromatic hydrocarbons: Health risk and adverse effects, photo-induced toxicity and regulating effect of microplastics

Polycyclic aromatic hydrocarbons (PAHs) are one of the most widely distributed persistent organic pollutants (POPs) in the environmental media. PAHs have been widely concerned due to their significant health risk and adverse effects to human and animals. Currently, the main sources of PAHs in the environment are the incomplete combustion of fossil fuels, as well as municipal waste incineration and agricultural non-surface source emissions. In this work, the scope of our attention includes 16 typical PAHs themselves without involving their metabolites and industrial by-products. Exposure of human and animals to PAHs can lead to a variety of adverse effects, including carcinogenicity and teratogenicity, genotoxicity, reproductive- and endocrine-disrupting effects, immunotoxicity and neurotoxicity, the type and severity of which depend on a variety of factors. On the other hand, the regulatory effect of microplastics (MPs) on the bio-toxicity and bioaccumulation capacity of PAHs has now gradually attracted attention. We critically reviewed the adsorption capacity and mechanisms of MPs on PAHs as well as the effects of MPs on PAHs toxicity, thus highlighting the importance of paying attention to the joint bio-toxicity caused by PAHs-MPs interactions. In addition, due to the extensive nature of the common exposure pathway of PAHs and ultraviolet ray, an accurate understanding of biological processes exposed to both PAHs and UV light is necessary to develop effective protective strategies. Finally, based on the above critical review, we highlighted the research gaps and pointed out the priority of further studies.

Diabetes, Oxidative Stress, and DNA Damage Modulate Cranial Neural Crest Cell Development and the Phenotype Variability of Craniofacial Disorders

Craniofacial malformations are among the most common birth defects in humans and they often have significant detrimental functional, aesthetic, and social consequences. To date, more than 700 distinct craniofacial disorders have been described. However, the genetic, environmental, and developmental origins of most of these conditions remain to be determined. This gap in our knowledge is hampered in part by the tremendous phenotypic diversity evident in craniofacial syndromes but is also due to our limited understanding of the signals and mechanisms governing normal craniofacial development and variation. The principles of Mendelian inheritance have uncovered the etiology of relatively few complex craniofacial traits and consequently, the variability of craniofacial syndromes and phenotypes both within families and between families is often attributed to variable gene expression and incomplete penetrance. However, it is becoming increasingly apparent that phenotypic variation is often the result of combinatorial genetic and non-genetic factors. Major non-genetic factors include environmental effectors such as pregestational maternal diabetes, which is well-known to increase the risk of craniofacial birth defects. The hyperglycemia characteristic of diabetes causes oxidative stress which in turn can result in genotoxic stress, DNA damage, metabolic alterations, and subsequently perturbed embryogenesis. In this review we explore the importance of gene-environment associations involving diabetes, oxidative stress, and DNA damage during cranial neural crest cell development, which may underpin the phenotypic variability observed in specific craniofacial syndromes.

Effects of benzo(a)pyrene at environmentally relevant doses on embryo-fetal development in rats

Studies have demonstrated that Benzo(a)Pyrene (BaP), a polycyclic aromatic hydrocarbon ubiquituous in the environment, can cause teratogenic effects. Since the majority of studies used in vitro models or high doses of BaP, this study evaluated the teratogenicity, reproductive and developmental performance of low doses of BaP through maternal and fetus examination after daily oral administration of BaP (0; 0.1; 1.0 or 10 μg/kg) to pregnant Wistar rats from Gestational day (GD) 6 to GD 15 (the organogenesis period). Pregnant rats did not exhibit clinical signs of toxicity during the exposure period. However, dams exposed to the lowest dose of BaP showed a reduction in the erythrocytes number and in the creatinine levels. The groups exposed to 0.1 and 1.0 μg/kg presented a decrease in placental efficiency, as well as an increase in placental weight. After fetal examination, the treated group with the lowest dose showed a reduced relative anogenital distance, while the curve of normal distribution of weight was changed in the highest dose group. In addition, anomalies evidenced by changes in the renal size and degree of fetal ossification were observed in treated-fetus. In conclusion, treatment with BaP during organogenesis at this dose level is detrimental to the normal development of fetuses.

The modulatory effect of taurine on benzo (a) pyrene-induced hepatorenal toxicity

Toxicities linked with Benzo (a) pyrene B[a]P exposure, particularly in liver and kidney have been reported in both animals and humans. Taurine (2-aminoethane sulfonic acid) is an intracellular β-amino acid reported to elicit hepatorenal protective functions. However, the modulatory effect of taurine on hepatorenal toxicity associated with exposure to B[a]P has not been reported. This study evaluated the effects of taurine on the hepatorenal toxicities induced in cohorts of rats exposed to B[a]P. Experimental rats were treated as follows: B[a]P (10 mg/kg); co-treated cohorts -B[a]P (10 mg/kg) plus taurine (100 or 200 mg/kg) for 4 successive weeks. Results show that co-dosing with taurine significantly (P < 0.05) improved B[a]P-induced distortion of oxidative stress markers (catalase, superoxide dismutase, glutathione S-transferase, glutathione peroxidase, total sulphydryl, reduced glutathione, lipid peroxidation and xanthine oxidase), renal function (urea and creatinine) and liver function marker enzymes (alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase and gamma glutamyl transferase). Moreover, taurine effectively mitigated increase in myeloperoxidase activity, levels of reactive oxygen and nitrogen species, nitric oxide and interleukin-1β in kidney and liver of rats treated with B[a]P. In conclusion, taurine modulates hepatorenal toxicity in B[a]P-exposed rats by suppressing hepatic and renal damage indices, oxidative injury and inflammatory stress.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and the risk of isolated congenital heart defects among offspring

BACKGROUND

Although there is evidence in experimental model systems that exposure to polycyclic aromatic hydrocarbons (PAHs) is linked with congenital heart defects (CHDs), few studies have examined the association in humans. We conducted a case-control study to examine the association between maternal exposure to PAHs and CHDs in offspring using data from the National Birth Defects Prevention Study (NBDPS) (1997-2011).

METHODS

We obtained detailed information on maternal occupation during the month before to three months after conception. Expert raters, masked to case-control status, assessed job descriptions to assign categorical levels of exposure. Categories were quantitatively mapped to estimate cumulative exposure to PAHs, incorporating exposure intensity, frequency, work duration, and work hours. Quartiles were generated for cumulative maternal exposure to PAHs. Crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using unconditional logistic regression for quartiles of PAH exposure and six CHD groupings (e.g. conotruncal) and specific subtypes (e.g. tetralogy of Fallot [ToF]). Final models were adjusted for maternal age, race/ethnicity, education, smoking, anticonvulsant use, folic acid supplementation, and study center.

RESULTS

There were 4,775 case and 7,734 control infants eligible for the study. The prevalence of occupational exposure to PAHs was 10.2% among both case and control mothers. In adjusted analysis, compared to mothers with no occupational PAH exposure, those in the highest quartile of exposure were more likely to have offspring in the conotruncal heart defects group (OR 1.41; 95% CI 1.00-2.00), and with ToF (OR 1.83; 95% CI 1.21-2.78).

CONCLUSIONS

Women in the highest quartile of estimated cumulative occupational PAH exposure during early pregnancy were more likely to have offspring with conotruncal heart defects, specifically ToF, compared to women with no occupational PAH exposure. Other comparisons between PAHs and other CHDs subgroups did not show any statistically precise associations.

6-Gingerol abates benzo[a]pyrene-induced colonic injury via suppression of oxido-inflammatory stress responses in BALB/c mice

Exposure to benzo[a]pyrene (BaP), the most toxic polycyclic aromatic hydrocarbon and a procarcinogen, is a global health concern which necessitates preventive measures. [6]-Gingerol (6-G), the most pharmacologically active constituent of ginger has been reported to promote gut health in various experimental settings. This study investigated the role of 6-G in BaP-induced colonic oxidative and inflammatory stress responses in mice. Experimental mice were randomly assigned into five groups of eight mice each and were orally gavage with BaP (125 mg/kg) singly or in combination with 6-G at 50 and 100 mg/kg for 14 consecutive days. Following sacrifice, the colonic activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), myeloperoxidase (MPO) as well as levels of glutathione (GSH), nitrites and lipid peroxidation (LPO) were assessed spectrophotometrically. Moreover, colonic concentration of epoxide hydrolase (EPXH), tumor necrosis factor alpha (TNF-α), interleukin-1 β (IL-1β), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) were assessed using ELISA. Administration of 6-G augmented BaP detoxification and colonic antioxidant status by increasing the EPXH, GST, SOD and CAT activities, GSH level with concomitant decrease in MDA level when compared with BaP alone group. In addition, 6-G suppressed BaP-induced colonic inflammation by decreasing MPO activity as well as nitrites, TNF-α, IL-1β, COX-2 and iNOS levels when compared with BaP alone group. In conclusion, 6-G protected against a decrease in colonic epoxide detoxifying enzymes and antioxidant defense mechanisms caused by BaP.

Antioxidants and Oxidative Stress: Focus in Obese Pregnancies

The prevalence of obesity in women of childbearing age around the globe has dramatically increased in the last decades. Obesity is characterized by a low-state chronic inflammation, metabolism impairment and oxidative stress, among other pathological changes. Getting pregnant in this situation involves that gestation will occur in an unhealthy environment, that can potentially jeopardize both maternal and fetal health. In this review, we analyze the role of maternal obesity-induced oxidative stress as a risk factor to develop adverse outcomes during gestation, including reduced fertility, spontaneous abortion, teratogenesis, preeclampsia, and intrauterine growth restriction. Evidences of macromolecule oxidation increase in reactive oxygen species generation and antioxidant defense alterations are commonly described in maternal and fetal tissues. Thus, antioxidant supplementation become an interesting prophylactic and therapeutic tool, that yields positive results in cellular, and animal models. However, the results from most meta-analysis studying the effect of these therapies in complicated gestations in humans are not really encouraging. It is still to be analyzed whether these therapies could work if applied to cohorts of patients at a high risk, such as those with low concentration of antioxidants or obese pregnant women.

Reactive Oxygen Species, Superoxide Dimutases, and PTEN-p53-AKT-MDM2 Signaling Loop Network in Mesenchymal Stem/Stromal Cells Regulation

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that can differentiate to various specialized cells, which have the potential capacity to differentiate properly and accelerate recovery in damaged sites of the body. This stem cell technology has become the fundamental element in regenerative medicine. As reactive oxygen species (ROS) have been reported to adversely influence stem cell properties, it is imperative to attenuate the extent of ROS to the promising protective approach with MSCs’ regenerative therapy. Oxidative stress also affects the culture expansion and longevity of MSCs. Therefore, there is great need to identify a method to prevent oxidative stress and replicative senescence in MSCs. Phosphatase and tensin homologue deleted on chromosome 10/Protein kinase B, PKB (PTEN/AKT) and the tumor suppressor p53 pathway have been proven to play a pivotal role in regulating cell apoptosis by regulating the oxidative stress and/or ROS quenching. In this review, we summarize the current research and our view of how PTEN/AKT and p53 with their partners transduce signals downstream, and what the implications are for MSCs’ biology.

Assessment of interaction between maternal polycyclic aromatic hydrocarbons exposure and genetic polymorphisms on the risk of congenital heart diseases

The major causes of congenital heart diseases (CHDs) are the interactions of genetic and environmental factors. We conducted a case–control study in 357 mothers of CHDs fetuses and 270 control mothers to investigate the association of maternal PAHs exposure, AHR, CYP1A1, CYP1A2, CYP1B1 and CYP2E polymorphisms, the interaction between PAHs exposure and genetic variants with the risk of CHDs. The higher level PAHs exposure was associated with the risk of CHDs (aOR = 2.029, 95% CI: 1.266, 3.251) or subtypes. The haplotypes of AHR or CYP1A2 were associated with the risk of CHDs: AHR: C-G-A-C: aOR = 0.765; T-A-G-A: aOR = 1.33; CYP1A2: A-T:aOR = 1.75; C-C: aOR = 0.706. When exposed to higher level PAHs, the risk of CHDs among the mothers carrying rs2158041 “C/T or T/T” genotype or rs7811989 “G/A or A/A” genotype in AHR was 1.724 (χ² = 7.209, P = 0.007) or 1.735 (χ² = 7.364, P = 0.007) times greater than the aOR in the mothers carrying wild genotype. The multiplicative-scale interactions between PAHs exposure and polymorphisms of CYP1A2 rs4646425 (P = 0.03) or CYP2E1 rs915908 (P = 0.0238) on the risk of CHDs were observed. Our study suggests that maternal AHR polymorphisms may modify the association of PAHs exposure with CHDs, CYP1A2 or CYP2E1 polymorphisms significantly interact with PAHs exposure on CHDs.

Modulatory Mechanism of Polyphenols and Nrf2 Signaling Pathway in LPS Challenged Pregnancy Disorders

Early embryonic loss and adverse birth outcomes are the major reproductive disorders that affect both human and animals. The LPS induces inflammation by interacting with robust cellular mechanism which was considered as a plethora of numerous reproductive disorders such as fetal resorption, preterm birth, teratogenicity, intrauterine growth restriction, abortion, neural tube defects, fetal demise, and skeletal development retardation. LPS-triggered overproduction of free radicals leads to oxidative stress which mediates inflammation via stimulation of NF-κB and PPARγ transcription factors. Flavonoids, which exist in copious amounts in nature, possess a wide array of functions; their supplementation during pregnancy activates Nrf2 signaling pathway which encounters pregnancy disorders. It was further presumed that the development of strong antioxidant uterine environment during gestation can alleviate diseases which appear at adult stages. The purpose of this review is to focus on modulatory properties of flavonoids on oxidative stress-mediated pregnancy insult and abnormal outcomes and role of Nrf2 activation in pregnancy disorders. These findings would be helpful for providing new insights in ameliorating oxidative stress-induced pregnancy disorders.

Fetal oxidative stress mechanisms of neurodevelopmental deficits and exacerbation by ethanol and methamphetamine

In utero exposure of mouse progeny to alcohol (ethanol, EtOH) and methamphetamine (METH) causes substantial postnatal neurodevelopmental deficits. One emerging pathogenic mechanism underlying these deficits involves fetal brain production of reactive oxygen species (ROS) that alter signal transduction, and/or oxidatively damage cellular macromolecules like lipids, proteins, and DNA, the latter leading to altered gene expression, likely via non-mutagenic mechanisms. Even physiological levels of fetal ROS production can be pathogenic in biochemically predisposed progeny, and ROS formation can be enhanced by drugs like EtOH and METH, via activation/induction of ROS-producing NADPH oxidases (NOX), drug bioactivation to free radical intermediates by prostaglandin H synthases (PHS), and other mechanisms. Antioxidative enzymes, like catalase in the fetal brain, while low, provide critical protection. Oxidatively damaged DNA is normally rapidly repaired, and fetal deficiencies in several DNA repair proteins, including oxoguanine glycosylase 1 (OGG1) and breast cancer protein 1 (BRCA1), enhance the risk of drug-initiated postnatal neurodevelopmental deficits, and in some cases deficits in untreated progeny, the latter of which may be relevant to conditions like autism spectrum disorders (ASD). Risk is further regulated by fetal nuclear factor erythroid 2-related factor 2 (Nrf2), a ROS-sensing protein that upregulates an array of proteins, including antioxidative enzymes and DNA repair proteins. Imbalances between conceptal pathways for ROS formation, versus those for ROS detoxification and DNA repair, are important determinants of risk. Birth Defects Research (Part C) 108:108-130, 2016. © 2016 Wiley Periodicals, Inc.

Learning and memory effects of neonatal methamphetamine exposure in rats: Role of reactive oxygen species and age at assessment

In utero methamphetamine (MA) exposure leads to a range of adverse effects, such as decreased attention, reduced working-memory capability, behavioral dysregulation, and spatial memory impairments in exposed children. In the current experiment, preweaning Sprague-Dawley rats-as a model of third trimester human exposure-were administered the spin trapping agent, N-tert-butyl-α-phenylnitrone (PBN), daily prior to MA. Rats were given 0 (SAL) or 40 mg/kg PBN prior to each MA dose (10 mg/kg, 4× per day) from postnatal day (P) 6-15. Littermates underwent Cincinnati water maze, Morris water maze, and radial water maze assessment beginning on P30 (males) or P60 (females). Males were also tested for conditioned contextual and cued freezing, while females were trained in passive avoidance. Findings show that, regardless of age/sex, neonatal MA induced deficits in all tests, except passive avoidance. PBN did not ameliorate these effects, but had a few minor effects. Taken together, MA induced learning deficits emerge early and persist, but the mechanism remains unknown.

In utero exposure to atypical antipsychotic drug, risperidone: Effects on fetal neurotoxicity in hippocampal region and cognitive impairment in rat offspring

Clinical studies indicate that about one-third of pregnant women with psychotic symptoms are exposed to either typical or atypical antipsychotic drugs (APDs). Reports on prenatal subject/model are lacking hence, the present study was undertaken to investigate the effect of prenatal exposure to risperidone (RIS) on the fetal hippocampus, and their related functional changes in young rat offspring. In this study, pregnant Wistar rats were exposed to equivalent therapeutic doses of RIS at 0.8mg/kg, 1.0mg/kg, and 2.0mg/kg BW from gestation days (GD) 6 to 20. On GD 21, about half of the pregnant subjects of each group were euthanized, their fetuses were collected, fetal brains dissected, and processed for neurohistopathological evaluation. Remaining pregnant dams were allowed to deliver naturally and reared up to 8weeks of age for neurobehavioral study under selected paradigms of cognition. Our results indicate that there was a significant decrease in the thickness of fetal hippocampus with the disturbed cytoarchitectural pattern, and volume of striatum and choroid plexus was also reduced. Furthermore, RIS treated young rat offspring displayed memory impairment on different mazes of learning and memory. The current study concludes that maternal exposure to clinically relevant doses of RIS may induce neurostructural changes in developing hippocampus and striatum, and cognitive sequelae in young offspring, respectively. Therefore, caution must be taken before prescribing this drug to pregnant subjects, especially during the sensitive phase of brain development. Hence, clinical correlation of animal data is urgently warranted.

The impact of oxidative DNA changes and ATM expression on morphological and functional activities on hepatocytes obtained from mesenchymal stem cells

Resistance to oxidative damages in undifferentiated mesenchymal stem cells (MSCs) in comparison with the undifferentiated progenitor cells may differ depending on several factors. This study was carried out to examine the impact of hepatogenic differentiation process of MSCs on oxidative DNA damage markers. Hepatic differentiation of MSCs was carried out using a two-step conventional protocol and the cells were processed for characterization using morphological and biochemical markers. During the course of differentiation cellular levels of reactive oxygen species (ROS), 8-hydroxy-2'-deoxyguanosine (8-OH-dG) and expression of ataxia-telangiectasia mutated (ATM) protein were estimated at time intervals (10, 20 and 30 days). The results showed a decrease in cellular ROS (13%, P < 0.05) at early stages of hepatogenic differentiation. Similarly, there was a small but significant decrease in 8-OH-dG level and ATM expression in differentiated hepatocytes. Despite the small changes in oxidative damage factors and ATM expression during the differentiation process, the hepatocytes obtained were morphologically and biologically intact.

Base excision DNA repair in the embryonic development of the sea urchin, Strongylocentrotus intermedius

In actively proliferating cells, such as the cells of the developing embryo, DNA repair is crucial for preventing the accumulation of mutations and synchronizing cell division. Sea urchin embryo growth was analyzed and extracts were prepared. The relative activity of DNA polymerase, apurinic/apyrimidinic (AP) endonuclease, uracil-DNA glycosylase, 8-oxoguanine-DNA glycosylase, and other glycosylases was analyzed using specific oligonucleotide substrates of these enzymes; the reaction products were resolved by denaturing 20% polyacrylamide gel electrophoresis. We have characterized the profile of several key base excision repair activities in the developing embryos (2 blastomers to mid-pluteus) of the grey sea urchin, Strongylocentrotus intermedius. The uracil-DNA glycosylase specific activity sharply increased after blastula hatching, whereas the specific activity of 8-oxoguanine-DNA glycosylase steadily decreased over the course of the development. The AP-endonuclease activity gradually increased but dropped at the last sampled stage (mid-pluteus 2). The DNA polymerase activity was high at the first cleavage division and then quickly decreased, showing a transient peak at blastula hatching. It seems that the developing sea urchin embryo encounters different DNA-damaging factors early in development within the protective envelope and later as a free-floating larva, with hatching necessitating adaptation to the shift in genotoxic stress conditions. No correlation was observed between the dynamics of the enzyme activities and published gene expression data from developing congeneric species, S. purpuratus. The results suggest that base excision repair enzymes may be regulated in the sea urchin embryos at the level of covalent modification or protein stability.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and craniosynostosis among offspring in the National Birth Defects Prevention Study

BACKGROUND

Evidence in animal models and humans suggests that exposure to polycyclic aromatic hydrocarbons (PAHs) may lead to birth defects. To our knowledge, this relationship has not been evaluated for craniosynostosis, a birth defect characterized by the premature closure of sutures in the skull. We conducted a case-control study to examine associations between maternal occupational exposure to PAHs and craniosynostosis.

METHODS

We used data from craniosynostosis cases and control infants in the National Birth Defects Prevention Study (NBDPS) with estimated delivery dates from 1997 to 2002. Industrial hygienists reviewed occupational data from the computer-assisted telephone interview and assigned a yes/no rating of probable occupational PAH exposure for each job from 1 month before conception through delivery. We used logistic regression to assess the association between occupational exposure to PAHs and craniosynostosis.

RESULTS

The prevalence of exposure was 5.3% in case mothers (16/300) and 3.7% in control mothers (107/2,886). We observed a positive association between exposure to PAHs during the 1 month before conception through the third month of pregnancy and craniosynostosis (odds ratio [OR] = 1.75; 95% confidence interval [CI], 1.01-3.05) after adjusting for maternal age and maternal education. The number of cases for each craniosynostosis subtype limited subtype analyses to sagittal craniosynostosis; the odds ratio remained similar (OR = 1.76, 95% CI, 0.82-3.75), but was not significant.

CONCLUSION

Our findings support a moderate association between maternal occupational exposure to PAHs and craniosynostosis. Additional work is needed to better characterize susceptibility and the role PAHs may play on specific craniosynostosis subtypes.

Breast cancer 1 (BRCA1)-deficient embryos develop normally but are more susceptible to ethanol-initiated DNA damage and embryopathies

The breast cancer 1 (brca1) gene is associated with breast and ovarian cancers, and heterozygous (+/−) brca1 knockout progeny develop normally, suggesting a negligible developmental impact. However, our results show BRCA1 plays a broader biological role in protecting the embryo from oxidative stress. Sox2-promoted Cre-expressing hemizygous males were mated with floxed brca1 females, and gestational day 8 +/− brca1 conditional knockout embryos with a 28% reduction in protein expression were exposed in culture to the reactive oxygen species (ROS)-initiating drug ethanol (EtOH). Untreated +/− brca1-deficient embryos developed normally, but when exposed to EtOH exhibited increased levels of oxidatively damaged DNA, measured as 8-oxo-2'-deoxyguanosine, γH2AX, which is a marker of DNA double strand breaks that can result from 8-oxo-2'-deoxyguanosine, formation, and embryopathies at EtOH concentrations that did not affect their brca1-normal littermates. These results reveal that even modest BRCA1 deficiencies render the embryo more susceptible to drug-enhanced ROS formation, and corroborate a role for DNA oxidation in the mechanism of EtOH teratogenesis.

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Heterozygous (+/−) brca1 conditional knockout (cKO) embryos develop normally.

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+/− brca1 cKO embryos have 28% less BRCA1 protein than wild-type (WT) littermates.

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Ethanol-exposed BRCA1-deficient mice have more oxidatively damaged DNA than WTs.

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Ethanol-exposed BRCA1 cKO embryos exhibit more embryopathies than WT littermates.

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BRCA1 protects the embryo from ethanol-enhanced oxidative stress—a novel role.

Developmental effects of parental exposure to soil contaminated with urban metals

Soil is a highly complex material, and because of rapid population growth, intense industrial activity and petrochemical development, it has suffered from contamination with substances of various origins. These environmental contaminants may have detrimental effects on human health, particularly during development. Due to the ability to transmit contaminants to the fetus, evaluating the effects of exposure of pregnant women on the psychomotor development of their offspring is of particular interest. Therefore, this study aimed to investigate the effects of exposure of female rats to an urban soil influenced by the dispersion of air contaminants during periods of pre-pregnancy, pregnancy and lactation on offspring development. Using physiological, behavioral and hematological parameters, deleterious effects on offspring were assessed. In behavioral parameters, parental exposure during pregnancy and lactation resulted in no significant differences in the evaluated parameters when compared to the control group. In contrast, pups from the pre-pregnancy group displayed decreased locomotor and exploratory activity in addition to increased levels of anxiety. Furthermore, offspring of rats exposed to contaminated urban soil during pre-pregnancy demonstrated significant changes in weight gain and development length and a reduction in the number of platelets compared to controls. Significantly, pups born to mothers exposed to contaminated urban soil during the pregnancy displayed changes in birth weight, weight gain during the growth, development length, incisor eruption and opening of the ears in addition to a reduction in their physical performance and a change in the number of lymphocytes. These results clearly show the negative influence of parental exposure to contaminated urban soil on the general development of the rats during the periods studied. These data indicate that developing organisms are highly sensitive to external factors. Further, they demonstrate the utility of these various biomarkers for identifying and displaying toxic effects of exposure to contaminated soils.

Maternal ambient air pollution exposure preconception and during early gestation and offspring congenital orofacial defects

BACKGROUND

Maternal air pollution exposure has been related to orofacial clefts but the literature is equivocal. Potential chronic preconception effects have not been studied.

OBJECTIVES

Criteria air pollutant exposure during three months preconception and gestational weeks 3-8 was studied in relation to orofacial defects.

METHODS

Among 188,102 live births and fetal deaths from the Consortium on Safe Labor (2002-2008), 63 had isolated cleft palate (CP) and 159 had isolated cleft lip with or without cleft palate (CL ±CP). Exposures were estimated using a modified Community Multiscale Air Quality model. Logistic regression with generalized estimating equations adjusted for site/region and maternal demographic, lifestyle and clinical factors calculated the odds ratio (OR) and 95% CI per interquartile increase in each pollutant.

RESULTS

Preconception, carbon monoxide (CO; OR=2.24; CI: 1.21, 4.16) and particulate matter (PM) ≤10 µm (OR=1.72; CI: 1.12, 2.66) were significantly associated with CP, while sulfur dioxide (SO2) was associated with CL ±CP (OR=1.93; CI: 1.16, 3.21). During gestational weeks 3-8, CO remained a significant risk for CP (OR=2.74; CI: 1.62, 4.62) and nitrogen oxides (NOx; OR=3.64; CI: 1.73, 7.66) and PM ≤2.5 µm (PM2.5; OR=1.74; CI: 1.15, 2.64) were also related to the risk. Analyses by individual week revealed that positive associations of NOx and PM2.5 with CP were most prominent from weeks 3-6 and 3-5, respectively.

CONCLUSIONS

Exposure to several criteria air pollutants preconception and during early gestation was associated with elevated odds for CP, while CL ±CP was only associated with preconception SO2 exposure.

The brominated flame retardant BDE-47 causes oxidative stress and apoptotic cell death in vitro and in vivo in mice

Polybrominated diphenyl ethers (PBDEs), used for decades as flame retardants, have become widespread environmental contaminants. Exposure is believed to occur primarily through diet and dust, and infants and toddlers have the highest body burden, raising concern for potential developmental neurotoxicity. The exact mechanisms of PBDE neurotoxicity have not been elucidated, but two relevant modes of action relate to impairment of thyroid hormone homeostasis and to direct effects on brain cells causing alterations in signal transduction, oxidative stress and apoptotic cell death. The present study shows that BDE-47 (2,2',4,4'-tetrabromodiphenyl ether) induces oxidative stress and ensuing apoptotic cell death in mouse cerebellar granule neurons in vitro. Similarly, in vivo administration of BDE-47, according to an exposure protocol shown to induce behavioral and biochemical alterations (10mg/kg, per os on post-natal day 10), induces oxidative stress and apoptosis, without altering serum levels of thyroid hormones. The effects of BDE-47 both in vitro and in vivo were more pronounced in a mouse model lacking the modifier subunit of glutamate cysteine ligase (GCLM) which results in reduced anti-oxidant capability due to low levels of GSH. Concentrations of BDE-47 in brain were in the mid-nanomolar range. These findings indicate that effects observed with BDE-47 in vitro are also present after in vivo administration, suggesting that in addition to potential endocrine effects, which were not seen here, direct interactions with brain cells should be considered as a potential mechanism of BDE-47 neurotoxicity.

Low-fidelity compensatory backup alternative DNA repair pathways may unify current carcinogenesis theories

The somatic mutation carcinogenesis theory has dominated for decades. The alternative theory, tissue organization field theory, argues that the development of cancer is determined by the surrounding microenvironment. However, neither theory can explain all features of cancer. As cancers share the features of uncontrolled proliferation and genomic instability, they are likely to have the same pathogenesis. It has been found that various DNA repair pathways within a cell crosstalk with one another, forming a DNA repair network. When one DNA repair pathways is defective, the others may work as compensatory backups. The latter pathways are explored for synthetic lethal anticancer therapy. In this article, we extend the concept of compensatory alternative DNA repair to unify the theories. We propose that the microenvironmental stress can activate low-fidelity compensatory alternative DNA repair, causing mutations. If the mutation occurs to a DNA repair gene, this secondarily mutated gene can lead to even more mutated genes, including those related to other DNA repair pathways, eventually destabilizing the genome. Therefore, the low-fidelity compensatory alternative DNA repair may mediate microenvironment-dependent carcinogenesis. The proposal seems consistent with the view of evolution: the environmental stress causes mutations to adapt to the changing environment.

Markers of macromolecular oxidative damage in maternal serum and risk of neural tube defects in offspring

Neural tube defects (NTDs) are among the most common and severe congenital malformations. To examine the association between markers of macromolecular oxidative damage and risk of NTDs, we measured levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), protein carbonyl (PC), and 8-iso-prostaglandin F2α (8-iso-PGF2α) in maternal serum samples of 117 women with NTD-affected pregnancies and 121 women with healthy term newborns. We found higher levels of 8-OHdG and PC in the NTD group than in the control group; however, we did not observe a statistically significant difference in 8-iso-PGF2α levels between the NTD and the control groups. NTD risk increased with increasing quartiles of 8-OHdG [odds ratio (OR)=1.17; 95% confidence interval (CI) 0.39-3.51; OR=2.19; 95% CI, 0.68-7.01; OR=3.70; 95% CI, 1.30-10.51, for the second, third, and fourth quartile relative to the lowest quartile, respectively; P=0.009], and with increasing quartiles of PC (OR=2.26; 95% CI, 0.66-7.69; OR=3.86; 95% CI, 1.17-12.80; OR=5.98; 95% CI, 1.82-19.66, for the second, third, and fourth quartile relative to the lowest quartile, respectively; P=0.002]. Serum levels of 8-OHdG were higher in women who did not take folic acid supplements during the periconceptional period. These results suggest that oxidative stress is present in women carrying pregnancies affected by NTDs.

Influence of intracellular zinc on cultures of rat cardiac neural crest cells

BACKGROUND

Developmental zinc (Zn) deficiency increases the incidence of heart anomalies in rat fetuses, in regions and structures derived from the outflow tract. Given that the development of the outflow tract requires the presence of cardiac neural crest cells (cNCC), we speculated that Zn deficiency selectively kills cNCC and could lead to heart malformations.

METHODS

Cardiac NCC were isolated from E10.5 rat embryos and cultured in control media (CTRL), media containing 3 μM of the cell permeable metal chelator N, N, N', N'-tetrakis (2-pyridylmethyl) ethylene diamine (TPEN), or in TPEN-treated media supplemented with 3 μM Zn (TPEN + Zn). Cardiac NCC were collected after 6, 8, and 24 h of treatment to assess cell viability, proliferation, and apoptosis.

RESULTS

The addition of TPEN to the culture media reduced free intracellular Zn pools and cell viability as assessed by low ATP production, compared to cells grown in control or Zn-supplemented media. There was an accumulation of reactive oxygen species, a release of mitochondrial cytochrome c into the cytoplasm, and an increased cellular expression of active caspase-3 in TPEN-treated cNCC compared to cNCC cultured in CTRL or TPEN + Zn media.

CONCLUSION

Zn deficiency can result in oxidative stress in cNCC, and subsequent decreases in their population and metabolic activity. These data support the concept that Zn deficiency associated developmental heart defects may arise in part as a consequence of altered cNCC metabolism.

Manganese superoxide dismutase and oxidative stress modulation

Oxidative stress is characterized by imbalanced reactive oxygen species (ROS) production and antioxidant defenses. Two main antioxidant systems exist. The nonenzymatic system relies on molecules to directly quench ROS and the enzymatic system is composed of specific enzymes that detoxify ROS. Among the latter, the superoxide dismutase (SOD) family is important in oxidative stress modulation. Of these, manganese-dependent SOD (MnSOD) plays a major role due to its mitochondrial location, i.e., the main site of superoxide (O(2)(·-)) production. As such, extensive research has focused on its capacity to modulate oxidative stress. Early data demonstrated the relevance of MnSOD as an O(2)(·-) scavenger. More recent research has, however, identified a prominent role for MnSOD in carcinogenesis. In addition, SOD downregulation appears associated with health risk in heart and brain. A single nucleotide polymorphism which alters the mitochondria signaling sequence for the cytosolic MnSOD form has been identified. Transport into the mitochondria was differentially affected by allelic presence and a new chapter in MnSOD research thus begun. As a result, an ever-increasing number of diseases appear associated with this allelic variation including metabolic and cardiovascular disease. Although diet and exercise upregulate MnSOD, the relationship between environmental and genetic factors remains unclear.

Oxidative DNA damage in the in utero initiation of postnatal neurodevelopmental deficits by normal fetal and ethanol-enhanced oxidative stress in oxoguanine glycosylase 1 knockout mice

Studies in mice with deficient antioxidative enzymes have shown that physiological levels of reactive oxygen species (ROS) can adversely affect the developing embryo and fetus. Herein, DNA repair-deficient progeny of oxoguanine glycosylase 1 (ogg1)-knockout mice lacking repair of the oxidative DNA lesion 8-oxo-2'-deoxyguanosine (8-oxodGuo) exhibited enhanced postnatal neurodevelopmental deficits, revealing the pathogenic potential of 8-oxodGuo initiated by physiological ROS production in fetal brain and providing the first evidence of a pathological phenotype for ogg1-knockout mice. Moreover, when exposed in utero to ethanol (EtOH), ogg1-knockout progeny exhibited higher levels of 8-oxodGuo in fetal brain and more severe postnatal neurodevelopmental deficits than wild-type littermates, both of which were blocked by pretreatment with the free radical trapping agent phenylbutylnitrone. These results suggest that ROS-initiated DNA oxidation, as distinct from altered signal transduction, contributes to neurodevelopmental deficits caused by in utero EtOH exposure, and fetal DNA repair is a determinant of risk.

Bacterial diversity losses: A potential extracellular driving mechanism involving the molecular ecological function of hydrophobic polycyclic aromatic hydrocarbons

The DNA transformation is vital to the horizontal gene transfer (HGT). The low-efficiency transformation of bare plasmid exposed to hydrophobic polycyclic aromatic hydrocarbons (PAHs) decreases the gene transfer level, and is possibly related to the loss of bacterial diversity at present. PAHs have great affinity for bare DNA through dispersion force and π–π overlap between PAHs and bases. These noncovalent interactions between PAHs and bases reduced the transformational efficiency of plasmid into bacterial recipients. Meanwhile these low-efficiency transformations for plasmid are controlled by the ions like Ca²⁺ in environment, in turn, presence of 0.5 mmol L⁻¹ Ca²⁺ recovered the efficiency from 3.2 (phenanthrene), 3.5 (pyrene) to about 4.45 and 4.75, respectively. The combination of Ca²⁺ with the —POO⁻— groups in DNA forms strong electrovalent bonds, weakening the molecular effect of DNA on PAHs and in turn promoting the gene transfer exposed to PAHs.

A mechanistic view of polybrominated diphenyl ether (PBDE) developmental neurotoxicity

Polybrominated diphenyl ethers (PBDEs), extensively used in the past few decades as flame retardants in a variety of consumer products, have become world-wide persistent environmental pollutants. Levels in North America are usually higher than those in Europe and Asia, and body burden is 3-to-9-fold higher in infants and toddlers than in adults. The latter has raised concern for potential developmental toxicity and neurotoxicity of PBDEs. Experimental studies in animals and epidemiological observations in humans suggest that PBDEs may be developmental neurotoxicants. Pre- and/or post-natal exposure to PBDEs may cause long-lasting behavioral abnormalities, particularly in the domains of motor activity and cognition. The mechanisms underlying the developmental neurotoxic effects of PBDEs are not known, though several hypotheses have been put forward. One general mode of action relates to the ability of PBDEs to impair thyroid hormone homeostasis, thus indirectly affecting the developing brain. An alternative or additional mode of action involves a direct effect of PBDEs on nervous system cells; PBDEs can cause oxidative stress-related damage (DNA damage, mitochondrial dysfunction, apoptosis), and interfere with signal transduction (particularly calcium signaling), and with neurotransmitter systems. Important issues such as bioavailability and metabolism of PBDEs, extrapolation of results to low level of exposures, and the potential effects of interactions among PBDE congeners and between PBDEs and other contaminants also need to be taken into account.

Can consumption of raw vegetables decrease the count of sister chromatid exchange? Results from a cross-sectional study in Krakow, Poland

Background

Sister chromatid exchange (SCE) is a widely used sensitive cytogenetic biomarker of exposure to genotoxic and cancerogenic agents. Results of human monitoring studies and cytogenetic damage have revealed that biological effects of genotoxic exposures are influenced by confounding factors related to life-style. Vegetable and fruit consumption may play a role, but available results are not consistent. The purpose of the study was to investigate the effect of consumption of raw and cooked vegetables and fruits on SCE frequency.

Methods

A total of 62 participants included colorectal cancer (CRC) patients, hospital-based controls and healthy laboratory workers. SCE frequency was assessed in blood lymphocytes. Frequency of vegetable and fruit consumption was gathered by structured semi-quantitative food frequency questionnaire.

Results

SCE frequency was lowest among hospital-based controls (4.4 ± 1.1), a bit higher in CRC patients (4.5 ± 1.0) and highest among laboratory workers (7.4 ± 1.2) (p < 0.05). Multivariable linear regression showed a significant inverse effect (b = −0.20) of raw vegetable consumption, but not so for intake of cooked vegetables and fruits.

Conclusions

The results of the study have shown the beneficial effect of consumption of raw vegetables on disrupted replication of DNA measured by SCE frequency, implying protection against genotoxic agents. Further effort is required to verify the role of cooked vegetables and fruits.

Congenital anomalies among live births in a high environmental risk area--a case-control study in Brindisi (southern Italy)

Maternal exposure to ambient pollution has been increasingly linked to the risk of congenital anomalies (CAs) in the fetus and newborns. Recently, a descriptive study in the high environmental risk city of Brindisi (Italy) revealed an increased prevalence of total CAs, especially congenital heart disease (CHD) and ventricular septal defects (VSDs), both at the local level and in comparison with the pool of EUROCAT registries. This paper concerns a population-based case control study to investigate the association between maternal exposure to air pollutants - sulfur dioxide (SO2) and total suspended particulate (TSP) matter - and the risk of CA. Cases were newborns up to 28 days of age, born to mothers resident in Brindisi between 2001 and 2010, and discharged with a diagnosis of CA. Cases and controls were individually matched according to sex, socio-economic status of the census area of residence of the mother, and year of beginning of pregnancy. Up to four controls were extracted for each case. Concentration data from monitoring stations were used to estimate air pollution exposure. Each case and control was assigned pollutant concentration values as mean and 90th percentile of the daily average values during weeks 3-8 of pregnancy. Exposure as both continuous and categorical variables was considered and a conditional logistic regression model was constructed to quantify the odds ratios of exposure to air pollutants and the occurrence of total CAs, CHDs and VSDs. We found exposure to the 90th percentile of SO2 to be associated with CHDs (p for trend =0.01) and VSDs (p for trend <0.05). Findings for TSP were less consistent. In conclusion, in the studied area, maternal exposure to sulfur dioxide increased risk of CHD.

A review of airborne polycyclic aromatic hydrocarbons (PAHs) and their human health effects

Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds comprised of two or more fused benzene rings arranged in various configurations. PAHs are widespread environmental contaminants formed as a result of incomplete combustion of organic materials such as fossil fuels. The occurrence of PAHs in ambient air is an increasing concern because of their carcinogenicity and mutagenicity. Although emissions and allowable concentrations of PAHs in air are now regulated, the health risk posed by PAH exposure suggests a continuing need for their control through air quality management. In light of the environmental significance of PAH exposure, this review offers an overview of PAH properties, fates, transformations, human exposure, and health effects (acute and chronic) associated with their emission to the atmosphere. Biomarkers of PAH exposure and their significance are also discussed.