Disruption of the blood-testis barrier integrity by bisphenol A in vitro: Is this a suitable model for studying blood-testis barrier dynamics?

Bisphenol A, an estrogenic environmental toxicant, has been implicated to have hazardous effects on reproductive health in humans and rodents. However, there are conflicting reports in the literature regarding its effects on male reproductive function. In this study, it was shown that in adult rats treated with acute doses of bisphenol A, a small but statistically insignificant percentage of seminiferous tubules in the testes displayed signs of germ cell loss, consistent with some earlier reports. It also failed to disrupt the blood-testis barrier in vivo. This is possibly due to the low bioavailability of free bisphenol A in the systemic circulation. However, bisphenol A disrupted the blood-testis barrier when administered to immature 20-day-old rats, consistent with earlier reports concerning the higher susceptibility of immature rats towards bisphenol A. This observation was confirmed using primary Sertoli cells cultured in vitro with established tight junction-permeability barrier that mimicked the blood-testis barrier in vivo. The reversible disruption of Sertoli cell tight junction barrier by bisphenol A was associated with an activation of ERK, and a decline in the levels of selected proteins at the tight junction, basal ectoplasmic specialization, and gap junction at the blood-testis barrier. Studies by dual-labeled immunofluorescence analysis and biotinylation techniques also illustrated declining levels of occludin, connexin 43, and N-cadherin at the cell-cell interface following bisphenol A treatment. In summary, bisphenol A reversibly perturbs the integrity of the blood-testis barrier in Sertoli cells in vitro, which can also serve as a suitable model for studying the dynamics of the blood-testis barrier. © 2009 Elsevier Ltd. All rights reserved.postprin

Radiation dose and cancer risk in retrospectively and prospectively ECG-gated coronary angiography using 64-slice multidetector CT

This study aimed to estimate the radiation dose and cancer risk to adults in England, the USA and Hong Kong associated with retrospectively and prospectively electrocardiogram (ECG)-gated coronary computed tomography angiography (CTA) using currently practised protocols in Hong Kong. The doses were simulated using the ImPACT spreadsheet. For retrospectively ECG-gated CTAwith pitches of 0.2, 0.22 and 0.24, the effective doseswere 27.7, 23.6 and 20.7 mSv, respectively, formales and 23.6, 20.0 and 18.8 mSv, respectively, for females. For prospectively ECG-gated CTA, the effective dose was 3.7 mSv for both males and females. A table of lifetime attributable risks (LAR) of cancer incidence was set up for the English population for the purpose of estimating cancer risk induced by low-dose radiation exposure, as previously reported for US and Hong Kong populations. From the tables, the LAR of cancer incidence for a representative 50-year-old subject was calculated for retrospectively ECG-gated CTA to be 0.112% and 0.227% for English males and females, respectively, 0.103%and 0.228%for USmales and females, respectively, and was comparatively higher at 0.137% and 0.370% for Hong Kong males and females, respectively; for prospectively ECG-gated CTA, the corresponding values were calculated to be 0.014% and 0.035% for English males and females, respectively, and 0.013%and 0.036%for US males and females, respectively, and againwere higher at 0.017%and 0.060% for Hong Kongmales and females, respectively. Our study shows that prospectively ECG-gated CTA reduces radiation dose and cancer risks by up to 87% compared with retrospectively ECG-gated CTA. © 2010 The British Institute of Radiology.link_to_OA_fulltex

Radiation dose and cancer risk from pediatric CT examinations on 64-slice CT: A phantom study

Objective: To measure the radiation dose from CT scans in an anthropomorphic phantom using a 64-slice MDCT, and to estimate the associated cancer risk. Materials and methods: Organ doses were measured with a 5-year-old phantom and thermoluminescent dosimeters. Four protocols; head CT, thorax CT, abdomen CT and pelvis CT were studied. Cancer risks, in the form of lifetime attributable risk (LAR) of cancer incidence, were estimated by linear extrapolation using the organ radiation doses and the LAR data. Results: The effective doses for head, thorax, abdomen and pelvis CT, were 0.7 mSv, 3.5 mSv, 3.0 mSv, 1.3 mSv respectively. The organs with the highest dose were; for head CT, salivary gland (22.33 mGy); for thorax CT, breast (7.89 mGy); for abdomen CT, colon (6.62 mGy); for pelvis CT, bladder (4.28 mGy). The corresponding LARs for boys and girls were 0.015-0.053% and 0.034-0.155% respectively. The organs with highest LARs were; for head CT, thyroid gland (0.003% for boys, 0.015% for girls); for thorax CT, lung for boys (0.014%) and breast for girls (0.069%); for abdomen CT, colon for boys (0.017%) and lung for girls (0.016%); for pelvis CT, bladder for both boys and girls (0.008%). Conclusion: The effective doses from these common pediatric CT examinations ranged from 0.7 mSv to 3.5 mSv and the associated lifetime cancer risks were found to be up to 0.16%, with some organs of higher radiosensitivity including breast, thyroid gland, colon and lungs. © 2010 Elsevier Ireland Ltd. All rights reserved.postprin

Family conflict and lower morning cortisol in adolescents and adults: modulation of puberty

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Recombinase technology: applications and possibilities

The use of recombinases for genomic engineering is no longer a new technology. In fact, this technology has entered its third decade since the initial discovery that recombinases function in heterologous systems (Sauer in Mol Cell Biol 7(6):2087–2096, 1987). The random insertion of a transgene into a plant genome by traditional methods generates unpredictable expression patterns. This feature of transgenesis makes screening for functional lines with predictable expression labor intensive and time consuming. Furthermore, an antibiotic resistance gene is often left in the final product and the potential escape of such resistance markers into the environment and their potential consumption raises consumer concern. The use of site-specific recombination technology in plant genome manipulation has been demonstrated to effectively resolve complex transgene insertions to single copy, remove unwanted DNA, and precisely insert DNA into known genomic target sites. Recombinases have also been demonstrated capable of site-specific recombination within non-nuclear targets, such as the plastid genome of tobacco. Here, we review multiple uses of site-specific recombination and their application toward plant genomic engineering. We also provide alternative strategies for the combined use of multiple site-specific recombinase systems for genome engineering to precisely insert transgenes into a pre-determined locus, and removal of unwanted selectable marker genes

RNA sequencing of identical twins discordant for autism reveals blood-based signatures implicating immune and transcriptional dysregulation

Background: A gap exists in our mechanistic understanding of how genetic and environmental risk factors converge at the molecular level to result in the emergence of autism symptoms. We compared blood-based gene expression signatures in identical twins concordant and discordant for autism spectrum condition (ASC) to differentiate genetic and environmentally driven transcription differences, and establish convergent evidence for biological mechanisms involved in ASC. Methods: Genome-wide gene expression data were generated using RNA-seq on whole blood samples taken from 16 pairs of monozygotic (MZ) twins and seven twin pair members (39 individuals in total), who had been assessed for ASC and autism traits at age 12. Differential expression (DE) analyses were performed between (a) affected and unaffected subjects (N = 36) and (b) within discordant ASC MZ twin pairs (total N = 11) to identify environmental-driven DE. Gene set enrichment and pathway testing was performed on DE gene lists. Finally, an integrative analysis using DNA methylation data aimed to identify genes with consistent evidence for altered regulation in cis. Results: In the discordant twin analysis, three genes showed evidence for DE at FDR < 10%: IGHG4, EVI2A and SNORD15B. In the case-control analysis, four DE genes were identified at FDR<10% including IGHG4, PRR13P5, DEPDC1B, and ZNF501. We find enrichment for DE of genes curated in the SFARI human gene database. Pathways showing evidence of enrichment included those related to immune cell signalling and immune response, transcriptional control and cell cycle/proliferation. Integrative methylomic and transcriptomic analysis identified a number of genes showing suggestive evidence for cis dysregulation. Limitations: Identical twins stably discordant for ASC are rare, and as such the sample size was limited and constrained to the use of peripheral blood tissue for transcriptomic and methylomic profiling. Given these primary limitations, we focused on transcript-level analysis. Conclusions: Using a cohort of ASC discordant and concordant MZ twins, we add to the growing body of transcriptomic-based evidence for an immune-based component in the molecular aetiology of ASC. Whilst the sample size was limited, the study demonstrates the utility of the discordant MZ twin design combined with multi-omics integration for maximising the potential to identify disease-associated molecular signals

Autoimmune-associated CLEC16A modulates inflammasome activity in human macrophages

Innate immunity: no. T.60C-type lectin domain family 16 member A (CLEC16A) is genetically-associated with a spectrum of autoimmune diseases including type I diabetes, multiple sclerosis and systemic lupus erythematosus (SLE). Functional characterization studies of Drosophila and mammalian CLEC16A homologues revealed their regulatory roles in different aspects of autophagy. Recent research advances in autophagy reveal its cross-regulatory relationship with inflammasome and have prompted us to evaluate the role of CLEC16A in inflammasome induction. The functional role of CLEC16A in inflammasome pathway was investigated using human monocyte-derived macrophages. Specific siRNAs targeting CLEC16A in macrophages resulted in a reduction in IL-1β secretion upon lipopolysaccharides stimulation with nigericin or poly(dA-dT), indicating that CLEC16 could modulate NLRP3 and AIM2 inflammasomes activity. Expression analyses showed that the inhibition of CLEC16A had minimal impact on mRNA levels of NLRP3, adaptor protein apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), interleukin-1 converting enzyme caspase-1 and the precursor pro-IL-1β, suggesting CLEC16A may act indirectly on the NLRP3 inflammasome pathway. Macrophages derived from SLE patients exhibited higher CLELC16A mRNA expression when compared with healthy controls. Interestingly, SLE macrophages produced more IL-1β upon NLRP3 as well as AIM2 inflammasomes activation. Taken together, CLEC16A may indirectly modulate inflammasome activity and affect IL-1β production in SLE macrophages. The mechanism involved is currently under further investigation

Cytokines and junction restructuring events during spermatogenesis in the testis: An emerging concept of regulation

During spermatogenesis in mammalian testes, junction restructuring takes place at the Sertoli-Sertoli and Sertoli-germ cell interface, which is coupled with germ cell development, such as cell cycle progression, and translocation of the germ cell within the seminiferous epithelium. In the rat testis, restructuring of the blood-testis barrier (BTB) formed between Sertoli cells near the basement membrane and disruption of the apical ectoplasmic specialization (apical ES) between Sertoli cells and fully developed spermatids (spermatozoa) at the luminal edge of the seminiferous epithelium occur concurrently at stage VIII of the seminiferous epithelial cycle of spermatogenesis. These two processes are essential for the translocation of primary spermatocytes from the basal to the apical compartment to prepare for meiosis, and the release of spermatozoa into the lumen of the seminiferous epithelium at spermiation, respectively. Cytokines, such as TNFα and TGFβ3, are present at high levels in the microenvironment of the epithelium at this stage of the epithelial cycle. Since these cytokines were shown to disrupt the BTB integrity and germ cell adhesion, it was proposed that some cytokines released from germ cells, particularly primary spermatocytes, and Sertoli cells, would induce restructuring of the BTB and apical ES at stage VIII of the seminiferous epithelial cycle. In this review, the intricate role of cytokines and testosterone to regulate the transit of primary spermatocytes at the BTB and spermiation will be discussed. Possible regulators that mediate cytokine-induced junction restructuring, including gap junction and extracellular matrix, and the role of testosterone on junction dynamics in the testis will also be discussed. © 2009 Elsevier Ltd. All rights reserved.link_to_OA_fulltex