Decreased DNA repair capacity caused by exposure to metal mixtures is modulated by the PARP1 rs1136410 variant in newborns from a polluted metropolitan area.

BACKGROUND: DNA damage caused by exposure to metal mixtures and the potential modulating role of genes involved in DNA repair and the antioxidant response have not been evaluated in newborns. AIM: The aim was to evaluate the association between prenatal exposure to metal mixtures and DNA repair capacity (DRC) in newborns from the Metropolitan Area of Mexico City (MAMC), a heavily polluted area, and the impact of variants in genes involved in DNA repair and the antioxidant response on this association. METHODS: We analyzed cord blood samples obtained at delivery from 125 healthy newborns from the MAMC. Twenty-four elements were determined by inductively coupled plasma mass spectrometry (ICP‒MS), but only 12 (Cu, I, Se, Zn, As, Ba, Cs, Mn, Sb, Sr, Pb, and Ti) were quantified in most samples. DRC was assessed by the challenge-comet assay, and OGG1, PARP1, and NFE2L2 genotyping was performed with TaqMan probes. Metal mixtures were identified and analyzed using principal component analysis (PCA) and weighted quantile sum (WQS) regression. Independent adjusted linear regression models were used to evaluate the associations. RESULTS: A null DRC was observed in 46% of newborns. The metals with the highest concentrations were Mn, Sr, Ti, and Pb. Essential elements showed normal levels. Only the mixture characterized by increased As, Cs, Cu, Se, and Zn levels was inversely associated with DRC. As was the principal contributor (37.8%) in the negative direction in the DRC followed by Ba and Sb, according to the WQS regression. Newborns carrying of the derived (G) allele of the PARP1 rs1136410 variant showed decreased DRC by exposure to some potentially toxic metals (PTMs) (As, Cs, and Ba). CONCLUSION: Prenatal exposure to metal mixtures negatively affected DRC in newborns, and the PARP1 rs1136410 variant had a modulating role in this association.

Temephos, an organophosphate larvicide for residential use: a review of its toxicity.

Temephos (O,O,O',O'-tetramethyl O,O'-thiodi-p-phenylene bis(phosphorothioate)) is a larvicide belonging to the family of organophosphate pesticides used for the control of different vectors of diseases, such as dengue, Zika, chikungunya, and dracunculiasis. The aim of this review was to discuss the available published information about temephos toxicokinetics and toxicity in mammals. Temephos is quickly absorbed in the gastrointestinal tract, distributed to all organs, and then it accumulates mainly in adipose tissue. It is metabolized by S-oxidation, oxidative desulfuration, and hydrolysis reactions, with the possible participation of cytochrome P450 (CYP). Temephos is mainly eliminated by feces, whereas some of its metabolites are eliminated by urine. The World Health Organization classifies it as class III: slightly dangerous with a NOAEL (no-observed adverse effect level) of 2.3 mg/kg/day for up to 90 days in rats, based on brain acetylcholinesterase (AChE) inhibition. A LOAEL (lowest observable adverse effect level) of 100 mg/kg/day for up to 44 days in rats was proposed based on cholinergic symptoms. However, some studies have shown that temephos causes toxic effects in mammals. The inhibition of the enzyme acetylcholinesterase (AChE) is one of its main demonstrated effects; however, this larvicide has also shown genotoxic effects and some adverse effects on male reproduction and fertility, as well as liver damage, even at low doses. We performed an extensive review through several databases of the literature about temephos toxicokinetics, and we recommend to revisit current assessment of temephos with the new available data.

Low concentrations of lead decrease the sperm fertilization ability by altering the acrosome reaction in mice.

Lead (Pb) exposure at high concentrations is associated with poor sperm quality, acrosome alterations, and low fertilization rate. Sperm capacitation and the acrosome reaction (AR) are required for successful fertilization. Actin polymerization is crucial for correct capacitation, and small GTPases, such as RhoA, Rac1, and Cdc42, are involved. This study aimed to evaluate the effects of Pb on sperm fertilization ability, capacitation, AR, and the mechanisms involved in mice exposed to low Pb concentrations. CD1 mice were exposed to 0.01% Pb2+ for 45 days through their drinking water and their spermatozoa were collected from the cauda epididymis-vas deferens to evaluate the following: AR (oAR: initial, sAR: spontaneous, and iAR: induced) using the PNA-FITC assay, sperm capacitation (P-Tyr levels), actin polymerization (phalloidin-TRITC), MDA production (stress oxidative marker), the RhoA, Rac1, and Cdc42 protein levels, and the in vitro fertilization (IVF). After the treatment, the blood Pb (PbB) concentration was 9.4 ±â€¯1.6 µg/dL. Abnormal sperm morphology and the oAR increased (8 and 19%, respectively), whereas the iAR decreased (15%) after a calcium ionophore challenge, and the actin polymerization decreased in the sperm heads (59%) and tails (42%). Rac1 was the only Rho protein to significantly decrease (33%). Spermatozoa from the Pb-treated mice showed a significant reduction in the fertilization rate (19%). Our data suggest that Pb exposure at environmental concentrations (PbB < 10 µg/dL) decreases the acrosome function and affects the sperm fertilization ability; this is probably a consequence of the low Rac1 levels, which did not allow adequate actin polymerization to occur.

In utero exposure to ultrafine particles promotes placental stress-induced programming of renin-angiotensin system-related elements in the offspring results in altered blood pressure in adult mice.

BACKGROUND: Exposure to particulate matter (PM) is associated with an adverse intrauterine environment, which can promote adult cardiovascular disease (CVD) risk. Ultrafine particles (UFP) (small size and large surface area/mass ratio) are systemically distributed, induce inflammation and oxidative stress, and have been associated with vascular endothelial dysfunction and arterial vasoconstriction, increasing hypertension risk. Placental stress and alterations in methylation of promoter regions of renin-angiotensin system (RAS)-related elements could be involved in UFP exposure-related programming of hypertension. We investigated whether in utero UFP exposure promotes placental stress by inflammation and oxidative stress, alterations in hydroxysteroid dehydrogenase 11b-type 2 (HSD11B2) and programming of RAS-related elements, and result in altered blood pressure in adult offspring. UFP were collected from ambient air using an aerosol concentrator and physicochemically characterized. Pregnant C57BL/6J pun/pun female mice were exposed to collected UFP (400 µg/kg accumulated dose) by intratracheal instillation and compared to control (nonexposed) and sterile H2O (vehicle) exposed mice. Embryo reabsorption and placental stress by measurement of the uterus, placental and fetal weights, dam serum and fetal cortisol, placental HSD11B2 DNA methylation and protein levels, were evaluated. Polycyclic aromatic hydrocarbon (PAH) biotransformation (CYP1A1 and NQO1 (NAD(P)H dehydrogenase (quinone)1)) enzymes, inflammation and oxidative stress in placentas and fetuses were measured. Postnatal day (PND) 50 in male offspring blood pressure was measured. Methylation and protein expression of (RAS)-related elements, angiotensin II receptor type 1 (AT1R) and angiotensin I-converting enzyme (ACE) in fetuses and lungs of PND 50 male offspring were also assessed. RESULTS: In utero UFP exposure induced placental stress as indicated by an increase in embryo reabsorption, decreases in the uterus, placental, and fetal weights, and HSD11B2 hypermethylation and protein downregulation. In utero UFP exposure induced increases in the PAH-biotransforming enzymes, intrauterine oxidative damage and inflammation and stimulated programming and activation of AT1R and ACE, which resulted in increased blood pressure in the PND 50 male offspring. CONCLUSIONS: In utero UFP exposure promotes placental stress through inflammation and oxidative stress, and programs RAS-related elements that result in altered blood pressure in the offspring. Exposure to UFP during fetal development could influence susceptibility to CVD in adulthood.

The organophosphate pesticide methamidophos opens the blood-testis barrier and covalently binds to ZO-2 in mice.

Methamidophos (MET) is an organophosphate (OP) pesticide widely used in agriculture in developing countries. MET causes adverse effects in male reproductive function in humans and experimental animals, but the underlying mechanisms remain largely unknown. We explored the effect of MET on mice testes (5 mg/kg/day/4 days), finding that this pesticide opens the blood-testis barrier and perturbs spermatogenesis, generating the appearance of immature germ cells in the epididymis. In the seminiferous tubules, MET treatment changed the level of expression or modified the stage-specific localization of tight junction (TJ) proteins ZO-1, ZO-2, occludin, and claudin-3. In contrast, claudin-11 was barely altered. MET also modified the shape of claudin-11, and ZO-2 at the cell border, from a zigzag to a more linear pattern. In addition, MET diminished the expression of ZO-2 in spermatids present in seminiferous tubules, induced the phosphorylation of ZO-2 and occludin in testes and reduced the interaction between these proteins assessed by co-immunoprecipitation. MET formed covalent bonds with ZO-2 in serine, tyrosine and lysine residues. The covalent modifications formed on ZO-2 at putative phosphorylation sites might interfere with ZO-2 interaction with regulatory molecules and other TJ proteins. MET bonds formed at ZO-2 ubiquitination sites likely interfere with ZO-2 degradation and TJ sealing, based on results obtained in cultured epithelial cells transfected with ZO-2 mutated at a MET target lysine residue. Our results shed light on MET male reproductive toxicity and are important to improve regulations regarding the use of OP pesticides and to protect the health of agricultural workers.

Acrosome reaction and chromatin integrity as additional parameters of semen analysis to predict fertilization and blastocyst rates.

BACKGROUND: Traditional semen parameters have shown little to none predictive value for fertilization and blastocyst viability for a successful pregnancy. Therefore, the purpose of this study was to explore the usefulness of incorporating the acrosome reaction (AR) and chromatin integrity to conventional semen analysis to individually predict the fertile potential of sperm samples. METHODS: A cross-sectional study was conducted in 69 participants undergoing IVF using oocyte donation. Semen samples were collected and evaluated for: AR [spontaneous (sAR) and induced (iAR)] by flow cytometry using anti-CD46-FITC, Acrosome Response to an Ionophore Challenge (ARIC), chromatin integrity by Sperm Chromatin Structure Assay (DNA Fragmentation Index-%DFI and High DNA Stainability-%HDS), WHO semen analysis, fertilization and blastocyst rates. RESULTS: The participant age was 40.0 ± 6.1 years (66% were normozoospermic). Sperm morphology, sAR, iAR, and ARIC were associated with the fertilization (ß = 3.56, R2 = 0.054; ß = - 5.92, R2 = 0.276; ß = 1.83, R2 = 0.150; and ß = 2.10, R2 = 0.270, respectively, p < 0.05). A logit model was developed to calculate the probability of fertilization (≥ 60%) for each participant, using the sperm morphology and ARIC as independent variables, followed by ROC analysis to determine a cutoff probability of 0.65 (specificity = 80.6%, sensitivity = 63.2%). %DFI was inversely associated with the viable blastocyst rate (ß = - 1.77, R2 = 0.057, p = 0.003), by the logit model and ROC analysis, a cutoff probability of 0.70 (specificity = 80.6%, sensitivity = 72.3%) was obtained to predict blastocyst viability (≥ 40%). There was no difference in the results with normozoospermic samples (n = 46). CONCLUSIONS: The incorporation of ARIC and %DFI allowed to obtain predictive models for high fertilization and blastocyst rates in an individualized way, being promising tools to improve the diagnosis of male fertility potential for research or assisted reproduction, even in men with unknown infertility.

Methamidophos alters sperm function and DNA at different stages of spermatogenesis in mice.

Methamidophos (MET) is a highly toxic organophosphate (OP) pesticide that is widely used in developing countries. MET has male reproductive effects, including decreased fertility. We evaluated MET effects on sperm quality, fertilization and DNA integrity, exploring the sensitivity of different stages of spermatogenesis. Adult male mice received MET (3.75 or 5mg/kg-bw/ip/day/4 days) and were euthanized 1, 28 or 45 days post-treatment (dpt) to evaluate MET's effects on epididymal maturation, meiosis or mitosis, respectively. Spermatozoa were obtained from the cauda epididymis-vas deferens and were evaluated for sperm quality, acrosome reaction (AR; Coomassie staining), mitochondrial membrane potential (by JC-1), DNA damage (comet assay), oxidative damage (malondialdehyde (MDA) production), in vitro fertilization and protein phosphorylation (immunodetection), and erythrocyte acetylcholinesterase (AChE) activity. At 1-dpt, MET inhibited AChE (43-57%) and increased abnormal cells (6%). While at 28- and 45-dpt, sperm motility and viability were significantly reduced with an increasing MET dose, and abnormal morphology increased at 5mg/kg/day/4 days. MDA and mitochondrial activity were not affected at any dose or time. DNA damage (OTM and %DNA) was observed at 5mg/kg/day/4 days in a time-dependent manner, whereas both parameters were altered in cells from mice exposed to 3.75 mg/kg/day/4 days only at 28-dpt. Depending on the time of collection, initial-, spontaneous- and induced-AR were altered at 5mg/kg/day/4 days, and the fertilization capacity also decreased. Sperm phosphorylation (at serine and tyrosine residues) was observed at all time points. Data suggest that meiosis and mitosis are the more sensitive stages of spermatogenesis for MET reproductive toxicity compared to epididymal maturation.

Comparative effect of technical and commercial formulations of methamidophos on sperm quality and DNA integrity in mice.

Methamidophos (MET), widely used in developing countries, is a highly neurotoxic organophosphate pesticide that has been associated with male reproductive alterations. Commercial formulations of pesticides used by agricultural workers and urban sprayers are responsible for thousands of intoxications in developing countries and may not have the same effects as active pure ingredients. Therefore, we compared effects of MET technical (METt) and commercial (METc) grades on sperm quality and DNA integrity. Male mice were injected (intraperitoneal, i.p.) with METt or METc (3.75, 5, and 7 mg/kg bw/day/4 days) and sacrificed 24 h post-treatment. Sperm cells collected from epididymis-vas deferens were evaluated for quality parameters, DNA damage by the comet assay, and lipoperoxidation by malondialdehyde (MDA) production. Erythrocyte acetylcholinesterase (AChE) activity was evaluated by acetylthiocholine inhibition as an index of overall toxicity. A dose-dependent AChE inhibition was observed with both formulations. Sperm quality was decreased after treatment with both MET compounds, but the commercial formulation showed stronger effects; a similar profile was observed with the DNA damage, being METc more genotoxic. None MET formulation increased MDA, suggesting no peroxidative damage involved. In summary, the commercial formulation of MET was more reprotoxic and genotoxic than the active pure ingredient, highlighting that commercial formulations must be considered for more appropriate risk assessment of pesticide exposures.

Prenatal Exposure to Potentially Toxic Metals and Their Effects on Genetic Material in Offspring: a Systematic Review.

In recent years, the background level of environmental pollutants, including metals, has increased. Pollutant exposure during the earliest stages of life may determine chronic disease susceptibility in adulthood because of genetic or epigenetic changes. The objective of this review was to identify the association between prenatal and early postnatal exposure to potentially toxic metals (PTMs) and their adverse effects on the genetic material of offspring. A systematic review was carried out following the Cochrane methodology in four databases: PubMed, Scopus, Web of Science, and the Cochrane Library. Eligible papers were those conducted in humans and published in English between 2010/01/01 and 2021/04/30. A total of 57 articles were included, most of which evaluated prenatal exposure. Most commonly evaluated PTMs were As, Cd, and Pb. Main adverse effects on the genetic material of newborns associated with PTM prenatal exposure were alterations in telomere length, gene or protein expression, mitochondrial DNA content, metabolomics, DNA damage, and epigenetic modifications. Many of these effects were sex-specific, being predominant in boys. One article reported a synergistic interaction between As and Hg, and two articles observed antagonistic interactions between PTMs and essential metals, such as Cu, Se, and Zn. The findings in this review highlight that the problem of PTM exposure persists, affecting the most susceptible populations, such as newborns. Some of these associations were observed at low concentrations of PTMs. Most of the studies have focused on single exposures; however, three interactions between essential and nonessential metals were observed, highlighting that metal mixtures need more attention.

Environmental polycyclic aromatic hydrocarbon (PAH) exposure and DNA damage in Mexican children.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants presenting a public health risk, particularly to children, a vulnerable population. PAHs have genotoxic and carcinogenic properties, which depend on their metabolism. Many enzymes involved in PAH metabolism, including CYP1A1, CYP1B1, GSTM and GSTT are polymorphic, which may modulate the activation/deactivation of these compounds. We evaluated PAH exposure and DNA damage in children living in the vicinity of the main petrochemical complex located in the Gulf of Mexico, and explored the modulation by genetic polymorphisms of PAH excretion and related DNA damage. The participants (n=82) were children aged 6-10y attending schools near the industrial area. Urinary 1-hydroxypyrene (1-OHP; a biomarker of PAH exposure) was determined by reverse-phase-HPLC; DNA damage by the comet assay (Olive Tail Moment (OTM) parameter); CYP1A1*2C and CYP1B1*3 polymorphisms by real time-PCR; and GSTM1*0 and GSTT1*0 by multiplex PCR. The median value of 1-OHP was 0.37µmol/mol creatinine; 59% of children had higher 1-OHP concentrations than those reported in environmentally exposed adults (0.24µmol/mol creatinine). A stratified analysis showed increased DNA damage in children with 1-OHP concentrations greater than the median value. We observed higher 1-OHP concentrations in children with CYP1A1*2C or GSTM1*0 polymorphisms, and a positive influence of CYP1A1*2C on OTM values in children with the highest PAH exposure. The data indicate that children living in the surroundings of petrochemical industrial areas are exposed to high PAH levels, contributing to DNA damage and suggesting an increased health risk; furthermore, data suggest that polymorphisms affecting activation enzymes may modulate PAH metabolism and toxicity.

Temephos Decreases Sperm Quality and Fertilization Rate and Is Metabolized in Rat Reproductive Tissues at Low-Dose Exposure.

Temephos is an organophosphorus pesticide used in control campaigns against vectors that transmit diseases, including dengue, a public health concern. The WHO classifies temephos in category III and its safe concentration (low-observable-adverse-effect level) in male rats is 100 mg/kg/day for up to 44 days. Temephos inhibits acetylcholinesterase (AChE) and is metabolized in different tissues, probably by mixed-function oxidases; one of its metabolites is bisphenol S (BPS), which is considered an endocrine disruptor. The aim of this study was to evaluate the effects of temephos on sperm function and its biotransformation in the testis, epididymis, and other tissues to explore its toxicity in rats treated with 100 mg/kg/day/5 or 7 days (gavage). AChE activity was inhibited 70% starting on day 3 and 13 or 41% mortality was observed at 5 or 7 days, respectively. After 7 days, temephos significantly decreased sperm motility (30%) and viability (10%) and increased (10%) lipoperoxidation, and the sperm DNA exhibited no damage. Temephos was distributed and metabolized in all tissues, with the highest levels observed in the adipose tissue and temephos levels were 16-fold higher in the epididymis than in the testis. Notably, BPS was observed in the testis. At 5 days, decreased sperm motility (12.5%) and viability (5.7%) were observed and sperm fertilization decreased (30%). These results suggest that temephos decreases sperm quality and fertilization capacity at recommended safe concentrations and that it is metabolized in male reproductive tissues. This pesticide places the reproductive health of exposed people at risk, suggesting the need to reevaluate its toxicity.

Paraoxonase 1 polymorphisms and haplotypes and the risk for having offspring affected with spina bifida in Southeast Mexico.

BACKGROUND: Spina bifida (SB) is a common congenital malformation in Southeast Mexico. Parents of children with SB reside in areas with frequent pesticide spraying or have agriculture activities, suggesting potential exposure to pesticides. Paraoxonase 1 (PON1) is the responsible enzyme for deactivation of organophosphates (OP) in the central nervous system. Polymorphisms of PON1 genes influence the catalytic activity and plasma protein level of the enzyme, therefore, genotypic characterization of PON1 gene represents a potential predictor for susceptibility to OP-related effects. METHODS: The frequency of PON1 haplotypes and polymorphisms (-108CT, L55M, and Q192R) were determined in this study. A case-control study was performed to evaluate the risk for having offspring affected by SB in 152 cases and 160 control parents. Polymorphisms were determined by PCR amplification and restriction fragment length polymorphism and Real Time-PCR. Odds ratios and confidence interval 95% were estimated. RESULTS: Genotype frequencies for the three PON1 polymorphisms were distributed according to Hardy-Weinberg expectations (p > 0.05) and were significantly different between cases and controls (p < 0.05). The heterozygous CT genotype of -108CT polymorphism, the RR genotype of Q192R polymorphism, both LM and MM genotypes of L55M polymorphism, and the haplotypes 221 and 222 (for -108CT, L55M, and Q192R) were associated with the risk for having a child affected by SB (p < 0.02). The heterozygous -108CT genotype was associated only maternally, whereas the heterozygous L55M genotype was relevant only in the fathers. The RR homozygous genotype was relevant both in mothers and fathers, suggesting the importance of this substrate-specific polymorphism. CONCLUSION: Results suggest that PON1 polymorphisms are relevant risk factors for having offspring affected with SB in this population from Southeast Mexico.

Methyl parathion causes genetic damage in sperm and disrupts the permeability of the blood-testis barrier by an oxidant mechanism in mice.

Methyl parathion (Me-Pa) is an extremely toxic organophosphorus pesticide still used in developing countries. It has been associated with decreased sperm function and fertility and with oxidative and DNA damage. The blood-testis barrier (BTB) is a structure formed by tight junction (TJ) proteins in Sertoli cells and has a critical role in spermatogenesis. We assessed the effect of repeated doses of Me-Pa (3-12 mg/kg/day for 5 days, i.p.) on sperm quality, lipid oxidation, DNA integrity, and BTB permeability in adult male mice and explored oxidation as a mechanism of toxicity. Me-Pa caused dose-dependent effects on sperm quality, lipoperoxidation, and DNA integrity. Testis histology results showed the disruption of spermatogenesis progression and atrophy of seminiferous tubules. The pesticide opened the BTB, as evidenced by the presence of a biotin tracer in the adluminal compartment of the seminiferous tubules. This effect was not observed after 45 days of exposure when a spermatogenic cycle had completed. The coadministration of the antioxidant α-tocopherol (50 mg/kg/day for 5 days, oral) prevented the effects of Me-Pa on sperm quality, DNA and the BTB, indicating the importance of oxidative stress in the damage generated by Me-Pa. As evidenced by immunochemistry, no changes were found in the localization of the TJ proteins of the BTB, although oxidation (carbonylation) of total proteins in testis homogenates was detected. Our results show that Me-Pa disturbs the BTB and that oxidation is involved in the observed toxic effects on sperm cells.

Differential sensitivity of male germ cells to mainstream and sidestream tobacco smoke in the mouse.

Cigarette smoking in men has been associated with increased chromosomal abnormalities in sperm and with increased risks for spontaneous abortions, birth defects and neonatal death. Little is known, however, about the reproductive consequences of paternal exposure to second-hand smoke. We used a mouse model to investigate the effects of paternal exposure to sidestream (SS) smoke, the main constituent of second-hand smoke, on the genetic integrity and function of sperm, and to determine whether male germ cells were equally sensitive to mainstream (MS) and SS smoke. A series of sperm DNA quality and reproductive endpoints were investigated after exposing male mice for two weeks to MS or SS smoke. Our results indicated that: (i) only SS smoke significantly affected sperm motility; (ii) only MS smoke induced DNA strand breaks in sperm; (iii) both MS and SS smoke increased sperm chromatin structure abnormalities; and (iv) MS smoke affected both fertilization and the rate of early embryonic development, while SS smoke affected fertilization only. These results show that MS and SS smoke have differential effects on the genetic integrity and function of sperm and provide further evidence that male exposure to second-hand smoke, as well as direct cigarette smoke, may diminish a couple's chance for a successful pregnancy and the birth of a healthy baby.

Modified CDKN2B (p15) and CDKN2A (p16) DNA methylation profiles in urban pesticide applicators.

Gene-specific changes in DNA methylation by pesticides in occupationally exposed populations have not been studied extensively. Of particular concern are changes in the methylation profile of tumor-suppressor, such as CDKN2B and CDKN2A, genes involved in oncogenesis. The aim of this study was to evaluate the methylation profiles of CDKN2B and CDKN2A genes in urban pesticide applicators and their relationship with occupational exposure to pesticides. A cross-sectional study was conducted in 186 urban pesticide applicators (categorized as high or moderate exposures) and 102 participants without documented occupational exposures to pesticides. Acute and chronic pesticide exposures were evaluated by direct measurement of urinary dialkylphosphates, organophosphate metabolites, and a structured questionnaire, respectively. Anthropometric characteristics, diet, clinical histories, and other variables were estimated through a validated self-reported survey. DNA methylation was determined by pyrosequencing of bisulfite-treated DNA. Decreased DNA methylation of the CDKN2B gene was observed in pesticide-exposed groups compared to the non-exposed group. In addition, increased methylation of the CDKN2A promoter was observed in the moderate-exposure group compared to the non-exposed group. Bivariate analysis showed an association between CDKN2B methylation and pesticide exposure, general characteristics, smoking status, and micronutrients, while changes in CDKN2A methylation were associated with pesticide exposure, sex, educational level, body mass index, smoking status, supplement intake, clinical parameters, and caffeine consumption. These data suggest that pesticide exposure modifies the methylation pattern of CDKN2B and CDKN2A genes and raise important questions about the role that these changes may play in the regulation of cell cycle activities, senescence, and aging.

PON1Q192R polymorphism is associated with lipid profile in Mexican men with Mayan ascendancy.

Paraoxonase (PON1) enzyme is associated with high-density lipoproteins (HDL) that prevents low-density lipoprotein (LDL) oxidation. PON1Q192R polymorphism is associated with a risk of coronary heart disease and low HDL levels in case-control studies, but the issue is yet unresolved. Mexico has shown an increase in cardiovascular diseases, and some genetic factors may play a role. Our purpose was to evaluate the association between PON1Q192R and L55M polymorphisms and serum lipid profile in a healthy Mexican population. Ninety unrelated male inhabitants from southeastern Mexico with Mayan ascendancy agreed to participate. Demographic characteristics, lifestyle and medical history were obtained by questionnaire. Lipid profile was determined by enzymatic methods, PON1 activity by using paraoxon and phenylacetate and PON1 genotype by real-time PCR. HDL-cholesterol (HDL-C) levels were associated with genotype: 192RR homozygote subjects had lower HDL-C levels than 192QQ homozygotes, and individuals with 192RR and 192QR genotypes had an odds ratio (OR)=7.05 (95% confidence interval (CI)=1.29-38.34) of having HDL-C <60 mg/dL. Individuals with higher paraoxonase activity (>600.18 U/L) had a slight risk (OR=4.9, 95% CI=0.83-22.02) of having HDL-C <60 mg/dL. PON155LM polymorphism was associated with higher LDL-cholesterol. PON1Q192R polymorphism showed a role in modulating lipid profile: 192RR homozygotes showed the least favorable lipoprotein levels.

Sperm chromatin alteration and DNA damage by methyl-parathion, chlorpyrifos and diazinon and their oxon metabolites in human spermatozoa.

Extensive use of organophosphorous pesticides (OP) by young men represents a public health problem. Toxicity of OP mainly results in neurotoxicity due to their oxygen analogues (oxons), formed during the OP oxidative activation. OP alter semen quality and sperm chromatin and DNA at different stages of spermatogenesis. Oxons are more toxic than the parent compounds; however, their toxicity to spermatogenic cells has not been reported. We evaluated sperm DNA damage by several OP compounds and their oxons in human spermatozoa from healthy volunteers incubated with 50-750 microM of methyl-parathion (MePA), methyl-paraoxon (MePO), chlorpyrifos (CPF), chlorpyrifos-oxon (CPO), diazinon (DZN) or diazoxon (DZO). All concentrations were not cytotoxic (evaluated by eosin-Y exclusion), except 750 microM MePO. Oxons were 15% to 10 times more toxic to sperm DNA (evaluated by the SCSA parameter, %DFI) than their corresponding parent compounds, at the following order: MePO>CPO=MePA>CPF>DZO>DZN, suggesting that oxon metabolites participate in OP sperm genotoxicity.

Environmental Epigenetic Changes, as Risk Factors for the Development of Diseases in Children: A Systematic Review.

BACKGROUND: Children are susceptible to environmental contaminants and are at risk of developing diseases, more so if the exposure begins at an early age. Epidemiological studies have postulated the hypothesis of the fetal origin of disease, which is mediated by epigenetic changes. Epigenetic marks are inheritable; they modulate the gene expression and can affect human health due to the presence of environmental factors. OBJECTIVE: This review focuses on DNA-methylation and its association with environmental-related diseases in children. METHODS: A search for studies related to DNA-methylation in children by pre- or post-natal environmental exposures was conducted, and those studies with appropriate designs and statistical analyses and evaluations of the exposure were selected. FINDINGS: Prenatal and early life environmental factors, from diet to exposure to pollutants, have been associated with epigenetic changes, specifically DNA-methylation. Thus, maternal nutrition and smoking and exposure to air particulate matter, polycyclic aromatic hydrocarbons, arsenic, heavy metals, persistent organic pollutants, and some endocrine disrupters during pregnancy have been associated with genomic and gene-specific newborns' DNA-methylation changes that have shown in some cases sex-specific patterns. In addition, these maternal factors may deregulate the placental DNA-methylation balance and could induce a fetal reprogramming and later-in-life diseases. CONCLUSIONS: Exposure to environmental pollutants during prenatal and early life can trigger epigenetic imbalances and eventually the development of diseases in children. The integration of epigenetic data should be considered in future risk assessments.

Relationship between LINE-1 methylation pattern and pesticide exposure in urban sprayers.

Recently a relationship has been reported between pesticide exposure and changes in global DNA methylation patterns. Urban sprayers are a particularly vulnerable population because of the high risk of pesticide exposure that their work implies. Therefore, the aim of this study was to estimate the changes in the Long Interspersed Nucleotide Element (LINE-1) in urban sprayers and its relationship with pesticide exposure. The study population consisted of 190 individuals stratified into three study groups: no occupational pesticide exposure; moderate exposure, and high exposure. Pesticide exposure and other external factors such as diet, lifestyle, and others were evaluated through a validated questionnaire, and the butyrylcholinesterase enzyme activity was evaluated spectrophotometrically and used as exposure biomarker. DNA methylation was evaluated by pyrosequencing on bisulfite-treated DNA. The results showed a significant decrease of %5mC in both the moderate- and high-exposure groups with respect to the non-exposed group (p < 0.05). In addition, alcohol intake was associated with a higher percentage of LINE- 1 methylation. In conclusion, our results suggest that occupational pesticide exposure and external factors appears to modify the DNA methylation pattern measured through LINE-1.