Interactions between Exposure to Environmental Polycyclic Aromatic Hydrocarbons and DNA Repair Gene Polymorphisms on Bulky DNA Adducts in Human Sperm

BACKGROUND: Nucleotide excision repair (NER) and base excision repair (BER) are the primary mechanisms for repair of bulky adducts caused by chemical agents, such as PAHs. It is expected that polymorphisms in NER or BER genes may modulate individual susceptibility to PAHs exposure. Here, we evaluate the effects of PAHs exposure and polymorphisms in NER and BER pathway, alone or combined, on polycyclic aromatic hydrocarbon-DNA (PAH-DNA) adducts in human sperm. METHODOLOGY/PRINCIPAL FINDINGS: Sperm PAH-DNA adducts were measured by immunofluorescent assay using flow cytometry in a sample of 465 infertile adults. Polymorphisms of XPA, XPD, ERCC1, XPF, and XRCC1 were determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques. The PAHs exposure was detected as urinary 1-hydroxypyrene (1-OHP) levels. In multivariate models adjusted for potential confounders, we observed that XRCC1 5'pUTR -T/C, Arg194Trp, Arg399Gln polymorphisms were associated with increased sperm adduct levels. Furthermore, the stratified analysis indicated that adverse effects of XRCC1 Arg194Trp, Arg399Gln polymorphisms on PAH-DNA adducts were detected only in the high PAHs exposure group. CONCLUSIONS/SIGNIFICANCE: These findings provided the first evidence that polymorphisms of XRCC1 may modify sperm PAH-DNA adduct levels and may be useful biomarkers to identify individuals susceptible to DNA damage resulting from PAHs exposure

Exposición al SARS-CoV-2 y la percepción del riesgo de los trabajadores en entornos no sanitarios de Hong Kong, Nanjing y Wuhan: Un estudio cualitativo multisitio

Introducción: Understanding risk perception that hinges on health-protective behaviors is central to strategies for prevention. Aim: To classify the pattern of potential risk of worker exposure to SARS-CoV-2, and to assess association with risk perception among non-healthcare workers Methods: In a multi-site, qualitative study, we conducted individual in-depth interviews and mini focus group discussions with employees, managerial staff and self-employees from Hong Kong (n=87), Nanjing (n=60), and Wuhan (n=60) between June 2020 and March 2021. Audios were transcribed and categorized by themes following Grounded Theory approach. Results: We identified seven major types of potential risk exposure pattern by category of parameters. The risk perceptions decreased among Type A workers, working at fixed location in office, and no/little contacts with clients/customers, and increased among workers having the concern of asymptomatic characteristics of SAR-CoV-2, daily contact with large size of the unfamiliar crowds, unhygienic behaviors of clients/customers, and use of public transportation to commute to work. The notion that the sense of safety deriving from the implementation and adherence with safety measures despite stringency, and trust with the government was most frequently reported in Nanjing and Wuhan. Conclusion: Study examines COVID-19 risks and risk perceptions among non-healthcare workers in three cities. Variations in risk perceptions were found, influenced by factors such as work patterns and safety measures. Trust in government and concerns about international contacts were common themes. The findings emphasize the need for targeted interventions, mental health support, and inclusive policies to address occupational health disparities and promote workplace safety.Introducción: Comprender la percepción del riesgo que condiciona conductas de protección de la salud es fundamental para la prevención. Objetivo: Clasificar el patrón del riesgo de exposición de los trabajadores al SRAS-CoV-2 y su asociación con la percepción del riesgo entre los trabajadores no sanitarios. Métodos: Estudio cualitativo multisitio. Realizamos entrevistas en profundidad y minigrupos de discusión con empleados, personal directivo y autoempleados de Hong Kong (n=87), Nanjing (n=60) y Wuhan (n=60) -junio 2020-marzo 2021-. Los audios se transcribieron y clasificaron por temas con enfoque de la teoría fundamentada. Resultados: Se identificaron siete tipos de patrón de exposición (Tipo A-G) al riesgo potencial. Las percepciones de riesgo disminuyeron entre trabajadores de tipo A que trabajaban en oficina y sin contacto con clientes y aumentaron entre trabajadores preocupados por características asintomáticas del SAR-CoV-2, contacto diario con multitudes, comportamientos antihigiénicos de clientes y uso de transporte público para ir al trabajo. La sensación de seguridad por aplicación y cumplimiento de medidas de seguridad y la confianza en el gobierno fue más frecuente en Nanjing y Wuhan. Conclusiones: Se hallaron variaciones en las percepciones del riesgo, influidas por factores como pautas de trabajo y medidas de seguridad. Fueron comunes la confianza en el gobierno y la preocupación por los contactos internacionales. Se requieren intervenciones específicas, apoyo a la salud mental y políticas integradoras para abordar las disparidades en salud laboral y promover la seguridad en el lugar de trabajo

Broadband all-fiber optical phase modulator based on photo-thermal effect in a gas-filled hollow-core fiber

We report broadband all-fiber optical phase modulation based on the photo-thermal effect in a gas-filled hollow-core fiber. The phase modulation dynamics are studied by multi-physics simulation. A phase modulator is fabricated using a 5.6-cm-long anti-resonant hollow-core fiber with pure acetylene filling. It has a half-wave optical power of 289 mW at 100 kHz and an average insertion loss 0.6 dB over a broad wavelength range from 1450 to 1650 nm. The rise and fall time constants are 3.5 and 3.7 μs, respectively, 2–3 orders of magnitude better than the previously reported microfiber-based photo-thermal phase modulators. The gas-filled hollow-core waveguide configuration is promising for optical phase modulation from ultraviolet to mid-infrared which is challenging to achieve with solid optical fibers

Idiopathic Male Infertility Is Strongly Associated with Aberrant Promoter Methylation of Methylenetetrahydrofolate Reductase (MTHFR)

Abnormal germline DNA methylation in males has been proposed as a possible mechanism compromising spermatogenesis of some men currently diagnosed with idiopathic infertility. Previous studies have been focused on imprinted genes with DNA methylation in poor quality human sperms. However, recent but limited data have revealed that sperm methylation abnormalities may involve large numbers of genes or shown that genes that are not imprinted are also affected.Using the methylation-specific polymerase chain reaction and bisulfite sequencing method, we examined methylation patterns of the promoter of methylenetetrahydrofolate reductase (MTHFR) gene (NG_013351: 1538-1719) in sperm DNA obtained from 94 idiopathic infertile men and 54 normal fertile controls. Subjects with idiopathic infertility were further divided into groups of normozoospermia and oligozoospermia. Overall, 45% (41/94) of idiopathic infertile males had MTHFR hypermethylation (both hemimethylation and full methylation), compared with 15% of fertile controls (P<0.05). Subjects with higher methylation level of MTHFR were more likely to have idiopathic male infertility (P-value for trend  = 0.0007). Comparing the two groups of idiopathic infertile subjects with different sperm concentrations, a higher methylation pattern was found in the group with oligozoospermia.Hypermethylation of the promoter of MTHFR gene in sperms is associated with idiopathic male infertility. The functional relevance of hypermathylation of MTHFR to male fertility warrants further investigation

Thyroid Disruption by Di-n-Butyl Phthalate (DBP) and Mono-n-Butyl Phthalate (MBP) in Xenopus laevis

BACKGROUND: Di-n-butyl phthalate (DBP), a chemical widely used in many consumer products, is estrogenic and capable of producing seriously reproductive and developmental effects in laboratory animals. However, recent in vitro studies have shown that DBP and mono-n-butyl phthalate (MBP), the major metabolite of DBP, possessed thyroid hormone receptor (TR) antagonist activity. It is therefore important to consider DBP and MBP that may interfere with thyroid hormone system. METHODOLOGY/PRINCIPAL FINDINGS: Nieuwkoop and Faber stage 51 Xenopus laevis were exposed to DBP and MBP (2, 10 or 15 mg/L) separately for 21 days. The two test chemicals decelerated spontaneous metamorphosis in X. laevis at concentrations of 10 and 15 mg/L. Moreover, MBP seemed to possess stronger activity. The effects of DBP and MBP on inducing changes of expression of selected thyroid hormone response genes: thyroid hormone receptor-beta (TRβ), retinoid X receptor gamma (RXRγ), alpha and beta subunits of thyroid-stimulating hormone (TSHα and TSHβ) were detected by qPCR at all concentrations of the compounds. Using mammalian two-hybrid assay in vitro, we found that DBP and MBP enhanced the interactions between co-repressor SMRT (silencing mediator for retinoid and thyroid hormone receptors) and TR in a dose-dependent manner, and MBP displayed more markedly. In addition, MBP at low concentrations (2 and 10 mg/L) caused aberrant methylation of TRβ in head tissue. CONCLUSIONS: The current findings highlight potential disruption of thyroid signalling by DBP and MBP and provide data for human risk assessment

Research on Stiffness of Multibackbone Continuum Robot Based on Screw Theory and Euler-Bernoulli Beam

Continuum robots have become a focus for extensive research, since they can work well in complex and confined environments. The main contribution of this paper is to establish a stiffness model of a single section multibackbone continuum robot and analyze the effect of the structural parameters of continuum robot on the overall rotation and translation stiffness. First, a stiffness model which indicates the end configuration of continuum robot under external load is deduced by the screw theory and Euler-Bernoulli beam. Then, the stiffness elements are fully analyzed, therefore, obtaining the influence of the structural parameters of continuum robot on the stiffness elements. Meanwhile, a numerical analysis of stiffness elements is given. Furthermore, the minimum and maximum rotation/translation stiffness are introduced to analyze the effect of the structural parameters of continuum robot on the overall rotation and translation stiffness. Finally, the experiments are used to validate the proposed stiffness model. The experimental results show that the proposed stiffness model of continuum robot is correct and the errors are less than 7%