Novel SPEF2 variants cause male infertility and likely primary ciliary dyskinesia.

PURPOSE: This study aimed to identify the genetic causes of male infertility and primary ciliary dyskinesia (PCD)/PCD-like phenotypes in three unrelated Han Chinese families. METHODS: We conducted whole-exome sequencing of three patients with male infertility and PCD/PCD-like phenotypes from three unrelated Chinese families. Ultrastructural and immunostaining analyses of patient spermatozoa and respiratory cilia and in vitro analyses were performed to analyze the effects of SPEF2 variants. Intracytoplasmic sperm injection (ICSI) was administered to three affected patients. RESULTS: We identified four novel SPEF2 variants, including one novel homozygous splicing site variant [NC_000005.10(NM_024867.4): c.4447 + 1G > A] of the SPEF2 gene in family 1, novel compound heterozygous nonsense variants [NC_000005.10(NM_024867.4): c.1339C > T (p.R447*) and NC_000005.10(NM_024867.4): c.1645G > T (p.E549*)] in family 2, and one novel homozygous missense variant [NC_000005.10(NM_024867.4): c.2524G > A (p.D842N)] in family 3. All the patients presented with male infertility and PCD/likely PCD. All variants were present at very low levels in public databases, predicted to be deleterious in silico prediction tools, and were further confirmed deleterious by in vitro analyses. Ultrastructural analyses of the spermatozoa of the patients revealed the absence of the central pair complex in the sperm flagella. Immunostaining of the spermatozoa and respiratory cilia of the patients validated the pathogenicity of the SPEF2 variants. All patients carrying SPEF2 variants underwent one ICSI cycle and delivered healthy infants. CONCLUSION: Our study reported four novel pathogenic variants of SPEF2 in three male patients with infertility and PCD/PCD-like phenotypes, which not only extend the spectrum of SPEF2 mutations but also provide information for genetic counseling and treatment of such conditions.

Involvement of the oncogenic small nucleolar RNA SNORA24 in regulation of p53 stability in colorectal cancer.

Colorectal cancer (CRC) is a common malignant cancer worldwide. Although the molecular mechanism of CRC carcinogenesis has been studied extensively, the details remain unclear. Small nucleolar RNAs (snoRNAs) have recently been reported to have essential functions in carcinogenesis, although their roles in CRC pathogenesis are largely unknown. In this study, we found that the H/ACA snoRNA SNORA24 was upregulated in various cancers, including CRC. SNORA24 expression was significantly associated with age and history of colon polyps in CRC patient cohorts, with high expression associated with a decreased 5-year overall survival. Our results indicated that the oncogenic function of SNORA24 is mediated by promoting G1/S phase transformation, cell proliferation, colony formation, and growth of xenograft tumors. Furthermore, SNORA24 knockdown induced massive apoptosis. RNA-sequencing and gene ontology (GO) enrichment analyses were performed to explore its downstream targets. Finally, we confirmed that SNORA24 regulates p53 protein stability in a proteasomal degradation pathway. Our study clarifies the oncogenic role of SNORA24 in CRC and advance the current model of the role of the p53 pathway in this process.

Blood trihalomethane concentrations in relation to sperm mitochondrial DNA copy number and telomere length among 958 healthy men.

BACKGROUND: In animal and human studies, exposure to trihalomethanes (THMs) has been associated with reduced semen quality. However, the underlying mechanisms remain poorly understood. OBJECTIVE: To investigate the associations of blood THM concentrations with sperm mitochondrial DNA copy number (mtDNAcn) and telomere length (TL) among healthy men. METHODS: We recruited 958 men who volunteered as potential sperm donors. A single blood sample was collected from each participant at recruitment and measured for chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM) concentrations. Within a 90-day follow-up, the last semen sample provided by each participant was quantified for sperm mtDNAcn and TL. We used multivariable linear regression models to assess the associations between blood THM concentrations and sperm mtDNAcn and TL. We also performed stratified analyses according to the time intervals between baseline blood THM determinations and semen collection (i.e., 0-9, 10-14, 15-69, or >69 days) to explore potential windows of susceptibility. RESULTS: After adjusting for potential confounders, we found inverse associations between quartiles (or categories) of blood TBM, brominated THM (Br-THM, the sum of BDCM, DBCM, and TBM), and total THM (TTHM, the sum of all four THMs) concentrations and sperm mtDNAcn (all P for trend≤0.03). Besides, we found inverse associations between quartiles of blood TCM, Br-THM, chlorinated THM (Cl-THM, the sum of TCM, BDCM, and DBCM), and TTHM concentrations and sperm TL (all P for trend<0.10). Stratified analyses showed stronger associations between Br-THM concentrations and sperm mtDNAcn determined 15-69 days since baseline exposure determinations, and between blood TCM and TTHM concentrations and sperm TL determined >69 days since baseline exposure determinations. CONCLUSION: Exposure to THMs may be associated with sperm mitochondrial and telomeric dysfunction.

Associations of Urinary Trichloroacetic Acid Concentrations with Spermatozoa Apoptosis and DNA Damage in a Chinese Population.

Exposure to trichloroacetic acid (TCAA) has been associated with impaired semen quality; however, its association with spermatozoa apoptosis and DNA damage remains unclear. We, therefore, collected single semen and repeated urine samples from male partners of couples attending a reproductive center, which were measured for spermatozoa apoptosis and DNA damage parameters and TCAA concentrations, respectively. Multivariable linear regression models were used to explore the associations between urinary TCAA concentrations and spermatozoa apoptosis (n = 462) and DNA damage parameters (n = 512). After adjusting for potential confounders, positive dose-response relationships were found between urinary TCAA concentrations and percentage of tail DNA (tail%) and tail-distributed moment (TDM) (both p for trend <0.10). Compared with men in the lowest tertile of urinary TCAA concentrations, men in the highest tertile had a greater tail% and TDM of 6.2% (95% CI: 0.7, 12.2%) and 8.9% (95% CI: -1.9, 20.5%), respectively. Urinary TCAA concentrations were unrelated to spermatozoa apoptosis parameters in a dose-response manner. However, urinary TCAA concentrations were positively associated with the percentage of Annexin V+/PI- spermatozoa (apoptotic cells), when urinary TCAA concentrations were modeled as continuous variables. Our results suggest that exposure to TCAA at concentrations in real-world scenarios may be associated with spermatozoa apoptosis and DNA damage.

Exposure to disinfection by-products and reproductive hormones among women: Results from the Tongji Reproductive and Environmental (TREE) study.

BACKGROUND: Disinfection by-products (DBPs) have been shown to impair female reproductive function. However, epidemiological evidence on reproductive hormones is scarce. OBJECTIVE: To investigate the associations between DBP exposures and reproductive hormones among women undergoing assisted reproductive technology. METHODS: We included 725 women from the Tongji Reproductive and Environmental (TREE) Study, an ongoing cohort conducted in Wuhan, China during December 2018 and January 2020. Urine samples collected at recruitment were quantified for dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) as biomarkers of DBP exposures. At day 2-5 of menstruation, serum reproductive hormones including luteinizing hormone (LH), estradiol (E2), total testosterone (T), progesterone (PRGE), and prolactin (PRL) were determined. Multivariate linear regression models were performed to assess the associations of urinary DCAA and TCAA concentrations with reproductive hormone levels. Dose-response relationships were investigated using natural cubic spline (NCS) and restricted cubic spline (RCS) models. RESULTS: After adjusting for relevant confounders, we observed that higher urinary DCAA levels were associated with increased serum PRGE (9.2%; 95% CI: -0.55%, 19.8% for the highest vs. lowest tertile; P for trend = 0.06). Based on NCS models, we observed U-shaped associations of urinary DCAA with serum PRGE and PRL; each ln-unit increment in urinary DCAA concentrations above 3.61 µg/L and 6.30 µg/L was associated with 18.9% (95% CI: 4.8%, 34.7%) and 23.3% (95% CI: -0.92%, 53.5%) increase in serum PRGE and PRL, respectively. The U-shaped associations were further confirmed in RCS models (P for overall association ≤0.01 and P for non-linear associations ≤0.04). We did not observe evidence of associations between urinary TCAA and reproductive hormones. CONCLUSION: Urinary DCAA but not TCAA was associated with altered serum PRGE and PRL levels among women undergoing assisted reproductive technology.

Reshuffling yeast chromosomes with CRISPR/Cas9.

Genome engineering is a powerful approach to study how chromosomal architecture impacts phenotypes. However, quantifying the fitness impact of translocations independently from the confounding effect of base substitutions has so far remained challenging. We report a novel application of the CRISPR/Cas9 technology allowing to generate with high efficiency both uniquely targeted and multiple concomitant reciprocal translocations in the yeast genome. Targeted translocations are constructed by inducing two double-strand breaks on different chromosomes and forcing the trans-chromosomal repair through homologous recombination by chimerical donor DNAs. Multiple translocations are generated from the induction of several DSBs in LTR repeated sequences and promoting repair using endogenous uncut LTR copies as template. All engineered translocations are markerless and scarless. Targeted translocations are produced at base pair resolution and can be sequentially generated one after the other. Multiple translocations result in a large diversity of karyotypes and are associated in many instances with the formation of unanticipated segmental duplications. To test the phenotypic impact of translocations, we first recapitulated in a lab strain the SSU1/ECM34 translocation providing increased sulphite resistance to wine isolates. Surprisingly, the same translocation in a laboratory strain resulted in decreased sulphite resistance. However, adding the repeated sequences that are present in the SSU1 promoter of the resistant wine strain induced sulphite resistance in the lab strain, yet to a lower level than that of the wine isolate, implying that additional polymorphisms also contribute to the phenotype. These findings illustrate the advantage brought by our technique to untangle the phenotypic impacts of structural variations from confounding effects of base substitutions. Secondly, we showed that strains with multiple translocations, even those devoid of unanticipated segmental duplications, display large phenotypic diversity in a wide range of environmental conditions, showing that simply reconfiguring chromosome architecture is sufficient to provide fitness advantages in stressful growth conditions.

Prenatal Exposure to Disinfection Byproducts and Intrauterine Growth in a Chinese Cohort.

Disinfection byproduct (DBP) exposure has been associated with birth size, pregnancy oxidative stress, and other adverse perinatal outcomes. However, little is known about the potential effect of prenatal DBP exposure on intrauterine growth. The present study included 1516 pregnant women from the Xiaogan Disinfection By-Products (XGDBP) birth cohort who were measured for four blood trihalomethanes [i.e., chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and two urinary haloacetic acids [i.e., dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA)] across pregnancy trimesters. Second- and third-trimester fetal ultrasound measures of the abdominal circumference (AC), head circumference, biparietal diameter, femur length, and estimated fetal weight and birth weight were converted into z-scores. After adjusting for potential confounders, linear mixed models showed a decreasing AC z-score across tertiles of blood brominated THM (Br-THMs, the sum of BDCM, DBCM, and TBM) and total THM (THM4, the sum of Br-THMs and TCM) concentrations (both p for trend <0.01). We also observed a decreasing AC z-score across categories of blood TBM during pregnancy trimesters (p for trend = 0.03). Urinary haloacetic acids were unrelated to fetal growth parameters. In summary, prenatal exposure to THMs, particularly during the first trimester, was associated with reduced fetal abdominal circumference.

A meta-analysis of the watch-and-wait strategy versus total mesorectal excision for rectal cancer exhibiting complete clinical response after neoadjuvant chemoradiotherapy.

BACKGROUND: Some clinical researchers have reported that patients with cCR (clinical complete response) status after neoadjuvant chemoradiotherapy (nCRT) could adopt the watch-and-wait (W&W) strategy. Compared with total mesorectal excision (TME) surgery, the W&W strategy could achieve a similar overall survival. Could the W&W strategy replace TME surgery as the main treatment option for the cCR patients? By using the meta-analysis method, we evaluated the safety and efficacy of the W&W strategy and TME surgery for rectal cancer exhibiting cCR after nCRT. METHODS: We evaluated two treatment strategies for rectal cancer with cCR after nCRT up to July 2021 by searching the Cochrane Library, PubMed, Wanfang, and China National Knowledge Infrastructure (CNKI) databases. Clinical data for primary outcomes (local recurrence, cancer-related death and distant metastasis), and secondary outcomes (disease-free survival (DFS) and overall survival (OS)) were collected to evaluate the efficacy and safety in the two groups. RESULTS: We included nine studies with 818 patients in the meta-analysis, and there were five moderate-quality studies and four high-quality studies. A total of 339 patients were in the W&W group and 479 patients were in the TME group. The local recurrence rate in the W&W group was greater than that in the TME group in the fixed-effects model (OR 8.54, 95% CI 3.52 to 20.71, P < 0.001). The results of other outcomes were similar in the two groups. CONCLUSION: The local recurrence rate of the W&W group was greater than that in the TME group, but other results were similar in the two groups. With the help of physical examination and salvage therapy, the W&W strategy could achieve similar treatment effects with the TME approach. TRIAL REGISTRATION: Protocol registration number: CRD42021244032 .

Urinary biomarker of strontium exposure is positively associated with semen quality among men from an infertility clinic.

Experimental studies have shown that nonradioactive strontium (Sr), in the form of Sr2+, have a positive effect on semen quality, but human evidence is lacking. This study aimed to examine the associations between nonradioactive Sr exposure and semen quality in Chinese men (n = 394). We recruited men who presented at an infertility clinic in Wuhan, China to seek for semen parameter analyses. Urinary Sr concentration as an exposure biomarker was measured using inductively coupled plasma mass spectrometer. We estimated the associations between urinary Sr concentrations and semen parameters using multivariable logistic and linear regression models. In multivariable linear regressions models, positive dose-response associations were estimated for sperm concentration, motility, and count across increasing urinary Sr quartiles (all p for trends<0.05), and the consistent positive associations were also observed for urinary Sr concentration modeled as a continuous exposure. In multivariable logistic models, decreased risks of below-reference sperm concentration, motility, and count were also estimated across increasing urinary Sr quartiles (all p for trends<0.05). Our results suggest that nonradioactive Sr exposure may have a beneficial effect on semen quality, but more investigations are warranted to confirm the results.

Identifying critical exposure windows for ambient air pollution and semen quality in Chinese men.

Emerging studies documented the association between ambient air pollution exposure and semen quality, but the critical exposure windows have not been comprehensively studied. To identify susceptible windows for associations of exposure to ambient respirable particulate matter (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3) with sperm concentration, sperm count, total motility, and progressive motility, we recruited 1061 men attending an infertility clinic in Wuhan, China, between 2011 and 2013. We used a distributed lag multivariate linear regression to assess the exposure-lag-response relationship between semen quality and weekly air pollution exposure. The critical exposure windows were during the 6th to 12th sperm development weeks for PM10, 10th to 11th weeks for O3, and 0 to 5th weeks for SO2. Over the entire 12 weeks of spermatogenesis period, an interquartile range increase (IQR) increase in PM10 was associated with declined sperm concentration [-45.64% (95% CI: -59.97%, -26.18%) percent decrease], declined sperm count [-49.42% (95% CI: -64.42%, -28.09%) percent decrease], reduced total motility [-12.42 (95% CI: -20.47, -4.37)], and reduced progressive motility [-8.81 (95% CI: -16.00, -1.61)], SO2 per IQR increase was associated with reduced sperm concentration [-39.73% (95% CI: -55.96%, -17.51%) percent decrease] and total motility [-8.64 (95% CI: -16.90, -0.38)], but NO2 and O3 were not associated with any of the four sperm quality parameters. Our findings suggest that exposure to PM10 during spermatidogenesis period, exposure to SO2 during spermatocytogenesis period, and exposure to O3 during spermiogenesis period were associated with impaired semen quality, which implies air pollutants impair semen quality through varied pathways.

Urinary Biomarker of Prenatal Exposure to Disinfection Byproducts, Maternal Genetic Polymorphisms in CYP2E1 and GSTZ1, and Birth Outcomes.

The effects of disinfection byproducts (DBPs) on adverse birth outcomes remain unsettled. Maternal genetic variants in relation to DBP metabolism may modify this effect. Pregnant women during late pregnancy (n = 1306) were included from a Chinese cohort. Maternal urinary trichloroacetic acid (TCAA) was measured as a biomarker of DBP exposure. Maternal genotyping was conducted in cytochrome P450 2E1 (CYP2E1; rs2031920, rs3813867, and rs915906) and glutathione S-transferase zeta-1 (GSTZ1; rs7975). The associations between maternal urinary TCAA and birth outcomes and statistical interactions between maternal exposure and genetic polymorphisms were estimated. We found that maternal urinary TCAA levels were associated with decreased birth weight (P for trend = 0.003) and ponderal index (P for trend = 0.004). Interaction analyses showed that maternal urinary TCAA in association with decreased birth weight was observed only among subjects with CYP2E1 rs3813867 GC/CC versus GG (Pint = 0.07) and associations with decreased birth length, ponderal index, and gestational age were observed only among subjects with GSTZ1 rs7975 GA/AA versus GG (Pint = 0.07, 0.02, and 0.02, respectively). Our results suggested that prenatal DBP exposure was negatively associated with birth weight and ponderal index, and maternal genetic polymorphisms in CYP2E1 and GSTZ1 might modify these associations.

Urinary biomarker of late pregnancy exposure to drinking water disinfection by-products and ultrasound measures of fetal growth in Wuhan, China.

BACKGROUND: Disinfection by-products (DBPs) have been shown to be reproductive and developmental toxicity. However, few studies examine the effect of prenatal exposure to DBPs on fetal growth via ultrasound measures. OBJECTIVE: To investigate the associations between maternal exposure to DBPs during late pregnancy and ultrasound measures of fetal growth. METHODS: We included 332 pregnant women who presented to a hospital to wait for delivery in Wuhan, China. Ultrasound parameters of fetal growth including femur length (FL), head circumference (HC), abdominal circumference (AC) and biparietal diameter (BPD) were assessed. We measured maternal TCAA concentrations in first morning urine collected from late pregnancy as a biomarker of in utero DBP exposure levels. Multivariable linear regression models were used to examine the associations between maternal urinary TCAA concentrations during late pregnancy and ultrasound parameters of fetal growth. RESULTS: We found that elevated maternal creatinine (Cr)-adjusted urinary TCAA levels had negative associations with BPD, HC and FL in boys but not in girls (P interaction = 0.04, 0.05 and 0.08, respectively). Male fetal BPD, HC and FL had decreases of 0.21 cm (95% CI: -0.35, -0.07; P for trend = 0.003), 0.46 cm (95% CI: -0.81, -0.10; P for trend = 0.01) and 0.17 cm (95% CI: -0.30, -0.04; P for trend = 0.01) for the highest vs. lowest tertile of Cr-adjusted urinary TCAA, respectively. These negative associations persisted for maternal Cr-adjusted urinary TCAA concentrations modeled as continuous variables. CONCLUSION: The results from our study suggest that maternal exposure to TCAA during late pregnancy may have adverse effects on male fetal growth.

Mediation of the relationship between phthalate exposure and semen quality by oxidative stress among 1034 reproductive-aged Chinese men.

BACKGROUND: Emerging evidence from animals indicates that oxidative stress plays a crucial role in the effects of phthalate exposure on male reproductive dysfunctions, which has never been thoroughly explored in humans. OBJECTIVE: To explore the potential mediating role of oxidative stress in the association of phthalate exposure with semen quality among 1034 Chinese men. METHOD: Repeated urine samples gathered from the male partners of sub-fertile couples were analyzed for 3 oxidative stress markers [8-hydroxy-2-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F2α (8-isoPGF2α) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)], using a liquid chromatography-tandem mass spectrometry. Multivariate regression models were constructed to evaluate the associations of urinary oxidative stress markers with urinary phthalate metabolites and semen quality. We also explored the potential mediation effects by oxidative stress markers. RESULTS: Significantly positive dose-dependent relationships were observed between each individual phthalate metabolite and all analyzed oxidative stress markers (all p for trend<0.05), except for monoethyl phthalate (MEP) in relation to HNE-MA. Additionally, significantly or suggestively inverse dose-dependent relationships were exhibited between urinary 8-isoPGF2α and sperm concentration (p for trend = 0.05), and between urinary 8-OHdG and percent of normal sperm morphology (p for trend = 0.01). Mediation analysis showed that urinary 8-isoPGF2α suggestively mediated 12% of the inverse association between monobutyl phthalate (MBP) and sperm concentration, and that urinary 8-OHdG suggestively mediated 32% of the inverse association of MEP with percent of normal sperm morphology (both p < 0.10). CONCLUSIONS: Although further investigations are required, our results suggest that oxidative stress may play a mediating role in the effects of phthalate exposure on impaired semen quality.

Profiles, variability and predictors of concentrations of blood trihalomethanes and urinary haloacetic acids along pregnancy among 1760 Chinese women.

Blood trihalomethanes (THMs) and urinary haloacetic acids (HAAs) are the leading candidate biomarkers for disinfection byproduct (DBP) exposure. However, no studies have assessed the exposure profiles, temporal variability, and potential predictors of these biomarkers during pregnancy. Here we collected blood (n = 4304) and urine samples (n = 4165) from 1760 Chinese pregnant women during early, mid-, and late pregnancy, which were separately analyzed for 4 THMs and 2 HAAs. We calculated the intraclass correlation coefficients (ICCs) to assess the variability of these biomarkers and estimated their correlations with sociodemographic, water-use behavioral, dietary and sample collection factors using mixed models. The median concentrations of TCM, BDCM, Br-THMs [sum of BDCM, dibromochloromethane (DBCM), bromoform (TBM)], total THMs (TTHMs, sum of TCM and Br-THMs), DCAA and TCAA in the water distribution system were 4.2 µg/L, 1.7 µg/L, 2.9 µg/L, 7.1 µg/L, 3.4 µg/L and 8.2 µg/L, respectively. Chloroform (TCM), bromodichloromethane (BDCM), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were detected in > 75% of the biospecimens. Repeated measurements of blood TCM, BDCM, Br-THMs and TTHMs and urinary DCAA and TCAA uniformly exhibited high variability (ICCs = 0.01-0.13); the use of a single measurement to classify gestational average exposure resulted in a high degree of exposure misclassification. The sampling season was a strong predictor of all analyzed DBPs. Additionally, we detected a positive association of blood TCM and BDCM with household income, urinary DCAA with age, and urinary TCAA with tap water usage, education level and amount of tap water consumed. Inverse associations were found between blood BDCM and vegetable consumption, and between blood Br-THM and TTHM and time interval since the last bathing/showering. Afternoon samples had lower DCAA concentrations than did early morning samples. Our results indicate that blood THM and urinary HAA concentrations vary greatly over the course of pregnancy and are affected by sampling season, time of day of blood/urine collection, sociodemographic factors, recent water-use activities and dietary intake.

Predictors and correlations of phthalate metabolite concentrations in urine and seminal plasma among reproductive-aged men.

BACKGROUND: Certain phthalates are suspected to be endocrine disruptors that are adversely associated with male reproductive health. However, the predictors and correlations of phthalate metabolite concentrations in urine and seminal plasma among reproductive-aged men have not been thoroughly studied. OBJECTIVE: To investigate the predictors and correlations of phthalate metabolite concentrations in urine and seminal plasma among adult Chinese males. METHOD: We measured mono-n-butyl phthalate (MBP), monobenzyl phthalate (MBzP), monomethyl phthalate (MMP), monoethyl phthalate (MEP), mono-n-octyl phthalate (MOP), mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) concentrations in seminal plasma and repeated spot-urine samples from 687 men who visited a reproductive center. Mixed-effect models were used to examine the associations of sociodemographic, lifestyle and medical factors with urinary metabolite concentrations. Linear regression models were used to identify predictors of metabolite concentrations in seminal plasma and correlations between metabolite concentrations in spot urine samples and seminal plasma. RESULTS: Measurements taken from spot urine samples poorly predicted same-day seminal plasma concentrations (all R2<0.10). Inverse associations were observed between education level and urinary MBP and MEOHP and between household income and urinary MMP; receiving intravenous infusion therapy was associated with increased urinary MBP, MEHHP and MEOHP, use of facial cleanser/cream was associated with increased MEP, and smoking was associated with increased MEHP. The predictors of metabolite concentrations in seminal plasma differed from those in urine, except for the association of intravenous infusion therapy with MBP. BMI was associated with increased seminal plasma MBP, MEHP and MEOHP, smoking was associated with increased MEP, and contact with plastics was associated with increased MEOHP. CONCLUSIONS: Phthalate metabolite concentrations in adult men varied in accordance with sociodemographic variables, lifestyle factors and intravenous therapy. Measures of metabolite levels in urine may not directly reflect the exposure status of the male reproductive system.

Investigating the performance of three modified activated sludge processes treating municipal wastewater in organic pollutants removal and toxicity reduction.

This study investigated the treatment performance of three types of modified activated sludge processes, i.e., anoxic/oxic (A/O), anaerobic/anoxic/oxic (A2/O) and oxidation ditch process, in treating municipal wastewater by measuring physicochemical and spectroscopic parameters, and the toxicity of the influents and effluents collected from 8 full-scale municipal wastewater treatment plants (MWTPs). The relationships between spectroscopic and physicochemical parameters of the wastewater samples and the applicability of the nematode Caenorhabditis elegans (C. elegans) bioassays for the assessment of the toxic properties of municipal wastewater were also evaluated. The results indicated that the investigated MWTPs employing any of A/O, A2/O and oxidation ditch processes could effectively control the discharge of major wastewater pollutants including biochemical oxygen demand (BOD), chemical oxygen demand, nitrogen and phosphorus. The oxidation ditch process appeared to have the advantage of removing tyrosine-like substances and presented slightly better removal efficiency of tryptophan-like fluorescent (peak T) substances than the A/O and A2/O processes. Both ultraviolet absorbance at 254nm and peak T may be used to characterize the organic load of municipal wastewater, and peak T can be adopted as a gauge of the BOD removal efficacy of municipal wastewater treatment. Using C. elegans-based oxygen consumption rate assay for monitoring municipal wastewater toxicity deserves further investigations.

Urinary Polycyclic Aromatic Hydrocarbon Metabolites and Human Semen Quality in China.

Toxicological studies have demonstrated that polycyclic aromatic hydrocarbons (PAHs) exposure impairs male reproductive health. However, the epidemiological evidence is limited and discordant. Our goal was to investigate the relationship between PAH exposures and human semen quality. We analyzed 12 urinary metabolites of PAHs from 933 men who sought semen quality analysis in an infertility clinic in Wuhan, China. Associations with semen quality were assessed using a multivariable linear regression. Restricted cubic splines were used to explore the dose-response relationships between urinary metabolites of PAHs and semen quality. We observed inverse associations between urinary 1-hydroxynaphthalene (1-OHNa) and sperm count, sperm concentration, and percentage of normal morphology (all p for trends <0.05) as well as between urinary ∑OHNa (sum of 1-OHNa and 2-OHNa) and sperm concentration (p for trend =0.04). Additionally, we found inverse associations between urinary 9-hydroxyphenanthrene (9-OHPh) and semen volume and sperm straight-line velocity (both p for trends <0.05) as well as between urinary ∑OHPh (sum of 1-, 2-, 3-, 4-, and 9-OHPh) and sperm count (p for trend =0.04). These dose-response relationships were further confirmed in the curves of the restricted cubic splines. Our data suggest that exposure to naphthalene and phenanthrene is related to decreased semen quality. Our results contribute to the growing body of evidence regarding the widespread exposure to PAHs and the detriment to male reproductive function.

Comparative cytotoxic and genotoxic potential of 13 drinking water disinfection by-products using a microplate-based cytotoxicity assay and a developed SOS/umu assay.

The implications of disinfection by-products (DBPs) present in drinking water are of public health concern because of their potential mutagenic, carcinogenic and other toxic effects on humans. In this study, we selected 13 main DBPs found in drinking water to quantitatively analyse their cytotoxicity and genotoxicity using a microplate-based cytotoxicity assay and a developed SOS/umu assay in Salmonella typhimurium TA1535/pSK1002. With the developed SOS/umu test, eight DBPs: 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-fura3-chloro-4-(dichloromethyl)-5-hydroxy-2-[5H]-furanone (MX), dibromoacetonitrile (DBN), iodoacetic acid (IA), bromochloroacetonitrile (BCN), bromoacetic acid (BA), trichloroacetonitrile (TCN), dibromoacetic acid (DBA) and dichloroacetic acid (DCA) were significantly genotoxic to S. typhimurium. Three DBPs: chloroacetic acid (CA), trichloroacetic acid (TCA) and dichloroacetonitrile (DCN) were weakly genotoxic, whereas the remaining DBPs: chloroacetonitrile (CN) and chloral hydrate (CH) were negative. The rank order in decreasing genotoxicity was as follows: MX > DBN > IA > BCN > BA > TCN > DBA > DCA > CA, TCA, DCN > CN, CH. MX was approximately 370 000 times more genotoxic than DCA. In the microplate-based cytotoxicity assay, cytotoxic potencies of the 13 DBPs were compared and ranked in decreasing order as follows: MX > IA > DBN > BCN > BA > TCN > DCN > CA > DCA > DBA > CN > TCA > CH. MX was approximately 19 200 times more cytotoxic than CH. A statistically significant correlation was found between cytotoxicity and genotoxicity of the 13 DBPs in S. typhimurium. Results suggest that microplate-based cytotoxicity assay and the developed SOS/umu assay are feasible tools for analysing the cytotoxicity and genotoxicity of DBPs, particularly for comparing their toxic intensities quantitatively.

Predictors of Third Trimester Blood Trihalomethanes and Urinary Trichloroacetic Acid Concentrations among Pregnant Women.

Prenatal exposure to disinfection byproducts (DBPs) has been associated with a variety of adverse birth outcomes. However, little is known about predictors of prenatal biomarkers of exposure to DBPs among pregnant women. We aimed to identify predictors of third trimester blood trihalomethanes (THMs) and urinary trichloroacetic acid (TCAA) concentrations, two biomarkers of exposure to DBPs, among pregnant women. Blood samples, urine samples, and questionnaires on individual characteristics and water-use activities were collected from 893 pregnant women in a Chinese cohort study. Maternal blood THM [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and urinary TCAA concentrations were measured. We used multivariable linear regression to identify the predictors of third trimester blood THM and creatinine-adjusted urinary TCAA concentrations. The geometric mean of blood TTHM (sum of TCM, BDCM, DBCM, and TBM) and creatinine-adjusted urinary TCAA concentrations were 51.90 ng/L and 9.66 µg/g creatinine, respectively. Study city was the strongest significant predictors of blood THM and creatinine-adjusted urinary TCAA concentrations. Prenatal body mass index (BMI) was associated with decreased blood THM and decreased creatinine-adjusted urinary TCAA concentrations. Age was associated with increased blood Br-THM (sum of BDCM, DBCM, and TBM) concentrations. Intake of boiled water and passive smoking were associated with lower blood THM concentrations. The predictors of blood THM and urinary TCAA concentrations identified in this study provide potential health implications on how to reduce DBP exposure during pregnancy.

Interactions between CYP2E1, GSTZ1 and GSTT1 polymorphisms and exposure to drinking water trihalomethanes and their association with semen quality.

Trihalomethanes (THMs) have been reported to be associated with altered semen quality, and this association may be modified by inherited differences in cytochrome P450 (CYP2E1) and glutathione S-transferase (GSTZ1 and GSTT1), which metabolize THMs. We conducted a cross-sectional study to examine the interactions between CYP2E1, GSTZ1 and GSTT1 polymorphisms and exposure to THMs on semen quality among 401 men from the Reproductive Center of Tongji Hospital in Wuhan China. The baseline blood concentrations of four individual THMs, chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (TBM), were measured as biomarkers of exposure to drinking water THMs. Genotypes were determined by real-time PCR, and semen-quality parameters were evaluated according to the World Health Organization guidelines. GSTT1 genotype significantly modified the association between exposure to Br-THMs (sum of BDCM, DBCM and TBM) and below-reference sperm motility (Pint=0.02). Men with above-median blood Br-THM levels had an increased odds ratio (OR) of below-reference sperm compared to men with below-median blood Br-THM levels (OR=2.15, 95% CI: 1.11, 4.19) in the GSTT1 null genotype only. In addition, we found that men with a TT of CYP2E1 rs 915,906 had higher blood TCM and TTHM (sum of TCM, BDCM, DBCM and TBM) concentrations than men with a CT/CC of CYP2E1 rs 915,906. Our results suggest that GSTT1 polymorphisms modify Br-THM exposure relation with semen quality, and CYP2E1 polymorphisms are associated with internal levels of exposure to THMs.