Investigating Tyrosine Phosphatases as Targets of Air Pollutants

Exposure to ambient particulate matter (PM) is associated with elevated rates of morbidity and mortality. Inflammation is thought to be a central mechanism by which PM exposure induces adverse health effects. In lung epithelial cells, a principle target of inhaled PM, proinflammatory signaling is mediated by phosphorylation-dependent signaling pathways whose activation is opposed by the activity of protein tyrosine phosphatases (PTPases), which thereby function to maintain signaling quiescence. PTPases contain an invariant catalytic cysteine that is susceptible to electrophilic attack. Therefore, we hypothesized that exposure to oxidative, electrophilic or metal cation components of ambient PM would impair PTPase activity allowing for unopposed basal tyrosine kinase activity. Here we report that exposure to the ubiquitous PM components Zn2+ or diesel exhaust particles (DEP) induce activation of the receptor tyrosine kinase Epidermal Growth Factor Receptor (EGFR) in primary human airway epithelial cells. This phosphorylation event occurs by a ligand-independent mechanism that requires EGFR kinase activity. We also show that exposure to Zn or DEP impair the activity of PTPases, which function to dephosphorylate the EGFR. These data provide a mechanism by which disparate components of ambient PM can similarly activate proinflammatory signaling in human lung cells. In summary, these data show that PM-induced EGFR-phosphorylation in human airway epithelial cells is the result of a loss of PTPase activities that normally function to dephosphorylate EGFR in opposition to baseline EGFR kinase activity.Doctor of Philosoph

Association between the colorectal cancer screening status of primary care physicians and their patients: Evidence from the Swiss Sentinella practice-based research network

Swiss health insurance reimburses screening for colorectal cancer (CRC) with either colonoscopy or fecal occult blood test (FOBT). Studies have documented the association between a physician's personal preventive health practices and the practices they recommend to their patients. We explored the association between CRC testing status of primary care physicians (PCP) and the testing rate among their patients. From May 2017 to September 2017, we invited 129 PCP who belonged to the Swiss Sentinella Network to disclose their CRC test status and whether they had been tested with colonoscopy or FOBT/other methods. Each participating PCP collected demographic data and CRC testing status from 40 consecutive 50- to 75-year-old patients. We analyzed data from 69 (54%) PCP 50 years or older and 2623 patients. Most PCP were men (81%); 75% were tested for CRC (67% with colonoscopy and 9% with FOBT). Mean patient age was 63; 50% were women; 43% had been tested for CRC (38%, 1000/2623 with colonoscopy and 5%, 131/2623, with FOBT or other non-endoscopic test). In multivariate adjusted regression models that clustered patients by PCP, the proportion of patients tested for CRC was higher among PCP tested for CRC than among PCP not tested (47% vs 32%; OR 1.97; 95% CI 1.36 to 2.85). Since PCP CRC testing status is associated with their patients CRC testing rates, it informs future interventions that will alert PCPs to the influence of their health decisions and motivate them to further incorporate the values and preferences of their patients in their practice

Disruption of VEGFR signaling leading to developmental defects

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Intramolecular Structural Heterogeneity altered by Long-range Contacts in an Intrinsically Disordered Protein

Short-range interactions and long-range contacts drive the 3D folding of structured proteins. The proteins' structure has a direct impact on their biological function. However, nearly 40% of the eukaryotes proteome is composed of intrinsically disordered proteins (IDPs) and protein regions that fluctuate between ensembles of numerous conformations. Therefore, to understand their biological function, it is critical to depict how the structural ensemble statistics correlate to the IDPs' amino acid sequence. Here, using small-angle x-ray scattering (SAXS) and time-resolved F\"orster resonance energy transfer (trFRET), we study the intra-molecular structural heterogeneity of the neurofilament low intrinsically disordered tail domain (NFLt). Using theoretical results of polymer physics, we find that the Flory scaling exponent of NFLt sub-segments correlates linearly with their net charge, ranging from statistics of ideal to self-avoiding chains. Surprisingly, measuring the same segments in the context of the whole NFLt protein, we find that regardless of the peptide sequence, the segments' structural statistics are more expanded than when measured independently. Our findings show that while polymer physics can, to some level, relate the IDP's sequence to its ensemble conformations, long-range contacts between distant amino acids play a crucial role in determining intra-molecular structures. This emphasizes the necessity of advanced polymer theories to fully describe IDPs ensembles with the hope it will allow us to model their biological function

Microbiota alter metabolism and mediate neurodevelopmental toxicity of 17β-estradiol

Estrogenic chemicals are widespread environmental contaminants associated with diverse health and ecological effects. During early vertebrate development, estrogen receptor signaling is critical for many different physiologic responses, including nervous system function. Recently, host-associated microbiota have been shown to influence neurodevelopment. Here, we hypothesized that microbiota may biotransform exogenous 17-βestradiol (E2) and modify E2 effects on swimming behavior. Colonized zebrafish were continuously exposed to non-teratogenic E2 concentrations from 1 to 10 days post-fertilization (dpf). Changes in microbial composition and predicted metagenomic function were evaluated. Locomotor activity was assessed in colonized and axenic (microbe-free) zebrafish exposed to E2 using a standard light/dark behavioral assay. Zebrafish tissue was collected for chemistry analyses. While E2 exposure did not alter microbial composition or putative function, colonized E2-exposed larvae showed reduced locomotor activity in the light, in contrast to axenic E2-exposed larvae, which exhibited normal behavior. Measured E2 concentrations were significantly higher in axenic relative to colonized zebrafish. Integrated peak area for putative sulfonated and glucuronidated E2 metabolites showed a similar trend. These data demonstrate that E2 locomotor effects in the light phase are dependent on the presence of microbiota and suggest that microbiota influence chemical E2 toxicokinetics. More broadly, this work supports the concept that microbial colonization status may influence chemical toxicity

Short Communications Proton MR Spectroscopy Correlates Diffuse Axonal Abnormalities with Post-Concussive Symptoms in Mild Traumatic Brain Injury

Abstract There are no established biomarkers for mild traumatic brain injury (mTBI), in part because post-concussive symptoms (PCS) are subjective and conventional imaging is typically unremarkable. To test whether diffuse axonal abnormalities quantified with three-dimensional (3D) proton magnetic resonance spectroscopic imaging ( 1 H-MRSI) correlated with patients' PCS, we retrospectively studied 26 mTBI patients (mean Glasgow Coma Scale [GCS] score of 14.7), 18-to 56-year-olds and 13 controls three to 55 days post-injury. All were scanned at 3 Tesla with T1-and T2-weighted MRI and 3D 1 H-MRSI (480 voxels over 360 cm 3 , *30% of the brain). On scan day, patients completed a symptom questionnaire, and those who indicated at least one of the most common subacute mTBI symptoms (headache, dizziness, sleep disturbance, memory deficits, blurred vision) were grouped as PCS-positive. Global gray matter and white matter (GM/WM) absolute concentrations of N-acetylaspartate (NAA), choline (Cho), creatine (Cr) and myo-inositol (mI) in PCS-positive and PCS-negative patients were compared to age-and gender-matched controls using two-way analysis of variance. The results showed that the PCS-negative group (n = 11) and controls (n = 8) did not differ in any GM or WM metabolite level. The PCS-positive patients (n = 15) had lower WM NAA than the controls (n = 12; 7.0 -0.6 versus 7.9 -0.5mM; p = 0.0007). Global WM NAA, therefore, showed sensitivity to the TBI sequelae associated with common PCS in patients with mostly normal neuroimaging, as well as GCS scores. This suggests a potential biomarker role in a patient population in which objective measures of injury and symptomatology are currently lacking

Modernizing persistence–bioaccumulation–toxicity (PBT) assessment with high throughput animal-free methods

The assessment of persistence (P), bioaccumulation (B), and toxicity (T) of a chemical is a crucial first step at ensuring chemical safety and is a cornerstone of the European Union’s chemicals regulation REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals). Existing methods for PBT assessment are overly complex and cumbersome, have produced incorrect conclusions, and rely heavily on animal-intensive testing. We explore how new-approach methodologies (NAMs) can overcome the limitations of current PBT assessment. We propose two innovative hazard indicators, termed cumulative toxicity equivalents (CTE) and persistent toxicity equivalents (PTE). Together they are intended to replace existing PBT indicators and can also accommodate the emerging concept of PMT (where M stands for mobility). The proposed “toxicity equivalents” can be measured with high throughput in vitro bioassays. CTE refers to the toxic effects measured directly in any given sample, including single chemicals, substitution products, or mixtures. PTE is the equivalent measure of cumulative toxicity equivalents measured after simulated environmental degradation of the sample. With an appropriate panel of animal-free or alternative in vitro bioassays, CTE and PTE comprise key environmental and human health hazard indicators. CTE and PTE do not require analytical identification of transformation products and mixture components but instead prompt two key questions: is the chemical or mixture toxic, and is this toxicity persistent or can it be attenuated by environmental degradation? Taken together, the proposed hazard indicators CTE and PTE have the potential to integrate P, B/M and T assessment into one high-throughput experimental workflow that sidesteps the need for analytical measurements and will support the Chemicals Strategy for Sustainability of the European Union

Modernizing persistence–bioaccumulation–toxicity (PBT) assessment with high throughput animal-free methods

The assessment of persistence (P), bioaccumulation (B), and toxicity (T) of a chemical is a crucial first step at ensuring chemical safety and is a cornerstone of the European Union’s chemicals regulation REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals). Existing methods for PBT assessment are overly complex and cumbersome, have produced incorrect conclusions, and rely heavily on animal-intensive testing. We explore how new-approach methodologies (NAMs) can overcome the limitations of current PBT assessment. We propose two innovative hazard indicators, termed cumulative toxicity equivalents (CTE) and persistent toxicity equivalents (PTE). Together they are intended to replace existing PBT indicators and can also accommodate the emerging concept of PMT (where M stands for mobility). The proposed “toxicity equivalents” can be measured with high throughput in vitro bioassays. CTE refers to the toxic effects measured directly in any given sample, including single chemicals, substitution products, or mixtures. PTE is the equivalent measure of cumulative toxicity equivalents measured after simulated environmental degradation of the sample. With an appropriate panel of animal-free or alternative in vitro bioassays, CTE and PTE comprise key environmental and human health hazard indicators. CTE and PTE do not require analytical identification of transformation products and mixture components but instead prompt two key questions: is the chemical or mixture toxic, and is this toxicity persistent or can it be attenuated by environmental degradation? Taken together, the proposed hazard indicators CTE and PTE have the potential to integrate P, B/M and T assessment into one high-throughput experimental workflow that sidesteps the need for analytical measurements and will support the Chemicals Strategy for Sustainability of the European Union.ISSN:0340-5761ISSN:1432-073

Early life perfluorooctanesulphonic acid (PFOS) exposure impairs zebrafish organogenesis

Additional authors (Zengxin Gai and Xue Ma) appear and the author order is revised on the published version of this article.As a persistent organic contaminant, perfluorooctanesulphonic acid (PFOS) has been widely detected in the environment, wildlife, and humans. The present study revealed that zebrafish embryos exposed to 16 µM PFOS during a sensitive window of 48-96 hour post-fertilization (hpf) disrupted larval morphology at 120 hpf. Malformed zebrafish larvae were characterized by uninflated swim bladder, less developed gut, and curved spine. Histological and ultrastructural examination of PFOS-exposed larvae showed structural alterations in swim bladder and gut. Whole genome microarray was used to identify the early transcripts dysregulated following exposure to 16 µM PFOS at 96 hpf. In total, 1,278 transcripts were significantly misexpressed (p < 0.05) and 211 genes were changed at least two-fold upon PFOS exposure in comparison to the vehicle exposed control group. A PFOS-induced network of perturbed transcripts relating to swim bladder and gut development revealed that misexpression of genes were involved in organogenesis. Taken together, early life stage exposure to PFOS perturbs various molecular pathways potentially resulting in observed defects in swim bladder and gut development.This is an author's peer-reviewed manuscript. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/aquatic-toxicology/.Keywords: Perfluorooctanesulfonic acid, Zebrafish embryo, Developmental toxicity, Swim bladder, GutKeywords: Perfluorooctanesulfonic acid, Zebrafish embryo, Developmental toxicity, Swim bladder, Gu

MicroRNAs control neurobehavioral development and function in zebrafish

microRNAs (miRNAs) have emerged as regulators of a broad spectrum of neurodevelopmental processes, including brain morphogenesis, neuronal differentiation, and survival. While the role of miRNAs in establishing and maintaining the developing nervous system is widely appreciated, the developmental neurobehavioral role of miRNAs has yet to be defined. Here we show that transient disruption of brain morphogenesis by ethanol exposure results in behavioral hyperactivity in larval zebrafish challenged with changes in lighting conditions. Aberrations in swimming activity persist in juveniles that were developmentally exposed to ethanol. During early neurogenesis, multiple gene expression profiling studies revealed widespread changes in mRNA and miRNA abundance in ethanol-exposed embryos. Consistent with a role for miRNAs in neurobehavioral development, target prediction analyses identified multiple miRNAs misexpressed in the ethanol-exposed cohorts that were also predicted to target inversely expressed transcripts known to influence brain morphogenesis. In vivo knockdown of miR9/9* or miR-153c persistently phenocopied the effect of ethanol on larval and juvenile swimming behavior. Structural analyses performed on adults showed that repression of miR-153c during development impacts craniofacial skeletal development. Together, these data support an integral role for miRNAs in the establishment of vertebrate neurobehavioral and skeletal systems.-Tal, T. L., Franzosa, J. A., Tilton, S. C., Philbrick, K. A., Iwaniec, U. T., Turner, R. T., Waters, K. M., Tanguay, R. L. MicroRNAs control neurobehavioral development and function in zebrafish. FASEB J. 26, 1452-1461 (2012). www.fasebj.orgKeywords: Brain, Morphogenesis, Alcohol, Conditional loss, Osteoblast differentiation, Gene expression, Microarray data, Neural progenitors, Ethanol exposure, Larval zebrafis