Unique hepatic maternal transfer pattern of trace metals and perfluoroalkyl substances (PFAS) in a bluntnose sixgill shark (Hexanchus griseus)

The fate and distribution of environmental contaminants includes bioaccumulation within marine organisms. A deceased 4-m long adult female bluntnose sixgill shark, pregnant with 72 pups, was recovered from Coles Bay on Vancouver Island, BC, Canada in 2019. This specimen provided a unique opportunity to examine maternal transfer of contaminants in a yolk-sac viviparous shark species. Liver subsamples of the adult and offspring were analyzed for 18 targeted inorganic elements by inductively coupled plasma optical emission spectroscopy (ICP-OES) and 21 targeted perfluoroalkyl substances (PFAS) by liquid chromatography-electrospray ionization-high resolution mass spectrometry (LC-ESI-Orbitrap MS). The maternal-offspring transfer efficiencies in liver tissue were subsequently examined for both contaminant classes. Concentrations of all detectable metals apart from calcium and magnesium were found to be higher in the mother compared to the offspring, including substantial levels of toxic cadmium (6 ± 2 mg kg-1 dw) and lead (7 ± 3 mg kg-1 dw). Conversely, high maternal transfer efficiencies were observed for PFAS (i.e., ΣPFAS = 71 ± 9 ng g-1 ww in offspring compared to 13 ± 9 ng g-1 ww in the mother). This study highlighted the unique maternal transfer characteristics of PFAS in bluntnose sixgill sharks depending on the structure of the polar head group, with greater liver-to-liver transfer efficiencies observed for perfluorocarboxylic acids (PFCAs) than perfluorosulfonic acids (PFSAs) of the same fluorocarbon chain length.

The association between per-/polyfluoroalkyl substances in serum and thyroid function parameters: A cross-sectional study on teenagers living near a Chinese fluorochemical industrial plant

Thyroid hormones (THs) play an important role in a wide range of crucial biological functions related to growth and development, and thyroid antibodies (TAs) can influence the biosynthesis of THs. Epidemiological studies have indicated that per- and polyfluoroalkyl substances (PFAS) could induce thyroid disruption, but studies on teenagers living in areas with high PFAS exposure are limited. This cross-sectional study focused on 836 teenagers (11- 15 years) living near a Chinese fluorochemical industrial plant. Decreased levels of free thyroxine (FT4, ﹤9.6 pmol/L, abnormal rate = 19.0 %) and elevated levels of free triiodothyronine (FT3, ﹥6.15 pmol/L, abnormal rate = 29.8 %) were observed. Correlations of serum PFAS concentrations and TAs/THs were analyzed. Increased PFOA was identified as a risk factor of decreased FT4 by using unadjusted (OR: 11.346; 95 % CI: 6.029, 21.352, p < 0.001) and adjusted (OR: 12.566; 95 % CI: 6.549, 24.115, p < 0.001) logistic regression models. In addition, significantly negative correlations were found between log10 transformed PFOA and FT4 levels using linear (unadjusted: β = -1.543, 95 % CI: -1.937, -1.148, p < 0.001; adjusted: β = -1.534, 95 % CI: -1.930, -1.137, p < 0.001) and BKMR models. For abnormal FT3, a significantly positive association between PFHxS and FT3 levels was observed in a regression model (unadjusted: β = -0.903, 95 % CI: -1.212, -0.595, p < 0.001; adjusted: β = -0.894, 95 % CI: -1.204, -0.583, p < 0.001), and PFHxS was identified as a risk factor (unadjusted: OR: 4.387; 95 % CI: 2.619, 7.346, p < 0.001; adjusted: OR: 4.527; 95 % CI: 2.665, 7.688, p < 0.001). Sensitivity analyses confirmed the robustness of the above results. This study reported the elevated PFAS exposure and thyroid function of teenagers living near a fluorochemical industrial plant from China.

Diindoles produced from commensal microbiota metabolites function as endogenous CAR/Nr1i3 ligands

Numerous studies have demonstrated the correlation between human gut bacteria and host physiology, mediated primarily via nuclear receptors (NRs). Despite this body of work, the systematic identification and characterization of microbe-derived ligands that regulate NRs remain a considerable challenge. In this study, we discover a series of diindole molecules produced from commensal bacteria metabolites that act as specific agonists for the orphan constitutive androstane receptor (CAR). Using various biophysical analyses we show that their nanomolar affinities are comparable to those of synthetic CAR agonists, and that they can activate both rodent and human CAR orthologues, which established synthetic agonists cannot. We also find that the diindoles, diindolylmethane (DIM) and diindolylethane (DIE) selectively up-regulate bona fide CAR target genes in primary human hepatocytes and mouse liver without causing significant side effects. These findings provide new insights into the complex interplay between the gut microbiome and host physiology, as well as new tools for disease treatment.

Molecular detection of pre-ribosomal RNAs of Mycobacterium bovis bacille Calmette-Guérin and Mycobacterium tuberculosis to enhance pre-clinical tuberculosis drug and vaccine development

Efforts are underway globally to develop effective vaccines and drugs against M. tuberculosis (Mtb) to reduce the morbidity and mortality of tuberculosis. Improving detection of slow-growing mycobacteria could simplify and accelerate efficacy studies of vaccines and drugs in animal models and human clinical trials. Here, a real-time reverse transcription PCR (RT-PCR) assay was developed to detect pre-ribosomal RNA (pre-rRNA) of Mycobacterium bovis bacille Calmette-Guérin (BCG) and Mtb. This pre-rRNA biomarker is indicative of bacterial viability. In two different mouse models, the presence of pre-rRNA from BCG and Mtb in ex vivo tissues showed excellent agreement with slower culture-based colony-forming unit assays. The addition of a brief nutritional stimulation prior to molecular viability testing further differentiated viable but dormant mycobacteria from dead mycobacteria. This research has set the stage to evaluate pre-rRNA as a BCG and/or Mtb infection biomarker in future drug and vaccine clinical studies.

Disclosing Environmental Ligands of L-FABP and PPARγ: Should We Re-evaluate the Chemical Safety of Hydrocarbon Surfactants?

Chemical contaminants can cause adverse effects by binding to the liver-fatty acid binding protein (L-FABP) and peroxisome proliferator-activated nuclear receptor γ (PPARγ), which are vital in lipid metabolism. However, the presence of numerous compounds in the environment has hindered the identification of their ligands, and thus only a small portion have been discovered to date. In this study, protein Affinity Purification with Nontargeted Analysis (APNA) was employed to identify the ligands of L-FABP and PPARγ in indoor dust and sewage sludge. A total of 83 nonredundant features were pulled-out by His-tagged L-FABP as putative ligands, among which 13 were assigned as fatty acids and hydrocarbon surfactants. In contrast, only six features were isolated when His-tagged PPARγ LBD was used as the protein bait. The binding of hydrocarbon surfactants to L-FABP and PPARγ was confirmed using both recombinant proteins and reporter cells. These hydrocarbon surfactants, along with >50 homologues and isomers, were detected in dust and sludge at high concentrations. Fatty acids and hydrocarbon surfactants explained the majority of L-FABP (57.7 ± 32.9%) and PPARγ (66.0 ± 27.1%) activities in the sludge. This study revealed hydrocarbon surfactants as the predominant synthetic ligands of L-FABP and PPARγ, highlighting the importance of re-evaluating their chemical safety.

Building the Environmental Chemical-Protein Interaction Network (eCPIN): An Exposome-Wide Strategy for Bioactive Chemical Contaminant Identification

Although advancements in nontargeted analysis have made it possible to detect hundreds of chemical contaminants in a single run, the current environmental toxicology approaches lag behind, precluding the transition from analytical chemistry efforts to health risk assessment. We herein highlighted a recently developed "top-down" bioanalytical method, protein Affinity Purification with Nontargeted Analysis (APNA), to screen for bioactive chemical contaminants at the "exposome-wide" level. To achieve this, a tagged functional protein is employed as a "bait" to directly isolate bioactive chemical contaminants from environmental mixtures, which are further identified by nontargeted analysis. Advantages of this protein-guided approach, including the discovery of new bioactive ligands as well as new protein targets for known chemical contaminants, were highlighted by several case studies. Encouraged by these successful applications, we further proposed a framework, i.e., the environmental Chemical-Protein Interaction Network (eCPIN), to construct a complete map of the 7 billion binary interactions between all chemical contaminants (>350,000) and human proteins (∼20,000) via APNA. The eCPIN could be established in three stages through strategically prioritizing the ∼20,000 human proteins, such as focusing on the 48 nuclear receptors (e.g., thyroid hormone receptors) in the first stage. The eCPIN will provide an unprecedented throughput for screening bioactive chemical contaminants at the exposome-wide level and facilitate the identification of molecular initiating events at the proteome-wide level.

Triclosan is the Predominant Antibacterial Compound in Ontario Sewage Sludge

Sewage treatment plants (STPs) accumulate both antibiotic and nonantibiotic antimicrobial compounds that can select for antibiotic resistant bacteria. Herein, we aimed to identify the predominant antibacterial compounds impacting E. coli from Ontario sewage sludge consisting of thousands of unknown compounds. Among the 10 extracted sludge samples, 6 extracts exerted significant growth inhibition effects in E. coli. A total of 103 compounds were tentatively detected across the 10 sludge samples by suspect screening, among which the bacterial enoyl-ACP reductase (FabI) inhibitor triclocarban was detected at the highest abundance. A hypomorphic FabI knockdown E. coli strain was highly susceptible to the sludge extracts, confirming FabI inhibitors as the primary antibacterial compounds in the sludge. Protein affinity pulldown identified triclosan as the major ligand binding to a His-tagged FabI protein from the sludge, despite the higher abundance of triclocarban in the same samples. Effect-directed analysis was used to determine the contributions of triclosan to the observed antibacterial potencies. Antibacterial effects were only detected in F₁₇ and F₁₈ across 20 fractions, which was consistent with the elution of triclosan and triclocarban in the same two fractions. Further, potency mass balance analysis confirmed that triclosan explained the majority (58-113%) of inhibition effects from sludge extracts. This study highlighted triclosan as the predominant antibacterial compound in sewage sludge impacting E. coli despite the co-occurrence of numerous other antibiotics and nonantibiotics.

Defining the Chemical Additives Driving In Vitro Toxicities of Plastics

Increases in the global use of plastics have caused concerns regarding potential adverse effects on human health. Plastic products contain hundreds of potentially toxic chemical additives, yet the exact chemicals which drive toxicity currently remain unknown. In this study, we employed nontargeted analysis and in vitro bioassays to identify the toxicity drivers in plastics. A total of 56 chemical additives were tentatively identified in five commonly used plastic polymer pellets (i.e., PP, LDPE, HDPE, PET, and PVC) by employing suspect screening and nontargeted analysis. Phthalates and organophosphates were found to be dominant in PVC pellets. Triphenyl phosphate and 2-ethylhexyl diphenyl phosphate accounted for a high amount (53.6%) of the inhibition effect of PVC pellet extract on human carboxylesterase 1 (hCES1) activity. Inspired by the high abundances of chemical additives in PVC pellets, six different end-user PVC-based products including three widely used PVC water pipes were further examined. Among them, extracts of PVC pipe exerted the strongest PPARγ activity and cell viability suppression. Organotins were identified as the primary drivers to these in vitro toxicities induced by the PVC pipe extracts. This study clearly delineates specific chemical additives responsible for hCES1 inhibition, PPARγ activity, and cell viability suppression associated with plastic.

Synthetical effect of microplastics and chiral drug amphetamine on a primary food source algae Chlorella pyrenoids

The biological effects and fate of the chiral illicit drug amphetamine in the presence and absence of microplastics on freshwater algae (Chlorella pyrenoids), including acute toxicity, growth inhibition, photosynthetic pigment content, oxidative stress, lipid peroxidation, and enantioselective fate were assessed. An agglomeration and the shading effects of microplastics in algae suspension were also determined. Microplastics were observed to increase the toxicity of amphetamine to algae and reduce algae cell growth. Exposed Chlorella pyrenoids exhibited a reduced algae cell counts in an agglomeration test, wherein algae cells decreased between 18% and 56% among treatment groups exposed to 5-50 mg L^-1 of microplastics. The agglomeration test suggested that microplastics might significantly increase the adverse effect on algae. Furthermore, our experiments demonstrated enantioselective degradation of amphetamine in algae, and demonstrated that the S-enantiomer was preferably degraded by algae cells. Adding microplastics to the algae suspension significantly reduced the enantioselectivity, with an EF value of 0.41 compared with amphetamine-alone group (0.34) after 21 d exposure. These results demonstrated the first evidence of microplastics acting as a vehicle to enhance amphetamine toxicity to Chlorella pyrenoids, as well as provided new insights into the co-effect of microplastics and organic contaminants on food source.

Behaviors and trophodynamics of o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT) in the aquatic food web: Comparison with p,p'-DDT

The broad-spectrum insecticide p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) has been banned in most countries since the 1970s on account of its environmental persistence as well as the high biomagnification of its major metabolite 1,1-dichloro-2,2-bis(4-chorophenyl)ethylene (p,p'-DDE). However, the information on the bioaccumulation and behavior of p,p'-DDTs in aquatic organisms is lacking. In this study, all 6 DDT isomers were detected in biota from the food web of the Liaodong Bay, China, and the total concentrations of DDT isomers in Chinese anchovy (Thrissa kammalensis) and Japanese Spanish mackerel (Scomberomrus niphonius) were 223 ± 42 ng/g ww and 242 ± 70 ng/g ww, respectively. In biota, o,p'-DDD dominated among the o,p'-isomers (80.5 ± 17.3%), while p,p'-DDE dominated among the p,p'-isomers (61.8 ± 15.2%). Contrastingly, sediment from the Liaodong Bay contained similar proportions of o,p'-DDT and p,p'-DDTs, suggesting an isomer-specific metabolism of the compounds in biota. A well-controlled laboratory exposure experiment with Japanese medaka (Oryzias latipes) demonstrated that o,p'-DDT was more difficult to metabolize to o,p'-DDE compared with that of p,p'-DDT. Significantly positive regressions were found between trophic levels and lipid equivalent concentrations for both o,p'-DDT and o,p'-DDD, and the trophic magnification factors (TMFs) were estimated as 12.3 and 9.12 (p < 0.05), respectively. The TMFs of o,p'-DDT and o,p'-DDD in the aquatic food web were higher than p,p'-DDT (7.76), p,p'-DDD (4.17), and p,p'-DDE (3.39), which may be explained by the isomer-specific metabolism differences in biota.

Ecological Role of 6OH-BDE47: Is It a Chemical Offense Molecule Mediated by Enoyl-ACP Reductases?

Although hydroxylated polybrominated diphenyl ethers (OH-BDEs) are among the most abundant natural organobromine compounds, the fundamental biological rationale for marine organisms to produce OH-BDEs remains elusive. Herein, we demonstrated that natural OH-BDEs exerted strong antibacterial activities against Escherichia coli by inhibiting enoyl-[acyl-carrier-protein] reductase (FabI), while anthropogenic OH-BDEs were inactive. Distinct from E. coli, OH-BDE-producing marine γ-proteobacteria including Marinomonas mediterranea MMB-1 (MMB-1) and Pseudoalteromonas luteoviolacea 2ta16 (Pl2ta16) exhibited resistance to 6OH-BDE47. An alternative enoyl-[acyl-carrier-protein] (ACP) reductase, FabV, was detected in all three OH-BDE-producing marine γ-proteobacteria. Thermal stability and protein affinity purification studies revealed that 6OH-BDE47 did not bind to recombinant or endogenous FabV of MMB-1 or Pl2ta16, demonstrating that FabV was the primary mechanism for OH-BDE-producing marine γ-proteobacteria to be resistant to 6OH-BDE47. To further confirm if the laboratory results were evidenced in the field, the 16S rRNA sequencing and metagenomics data from seven field-collected marine sponges were analyzed. Notably, the two Clade 4 sponges containing high concentrations of 6OH-BDE47 exhibited a distinct microbiome community structure compared to the other analyzed clades. Correspondingly, FabV was found to be selectively enriched in the same Clade 4 sponges. The merged evidence from the laboratory experiments and field studies demonstrated that 6OH-BDE47 may act as a chemical offense molecule in marine sponges.

The impact of COVID-19 on road safety in Canada and the United States

The COVID-19 pandemic has led to the implementation of unprecedented public health measures. The effect of these lockdown measures on road safety remain to be fully understood, however preliminary data shows reductions in traffic volume and increases in risky driving behaviors. The objective of the present study is to compare self-reported risky driving behaviors (speeding, distracted driving, drinking and driving, and drugged driving) during the pandemic in Canada and the U.S. to determine what differences exist between these two countries. Data was collected using the Road Safety Monitor (RSM), an annual online public opinion survey that investigates key road safety issues, administered to a representative sample of N = 1,500 Canadian drivers and N = 1,501 U.S. drivers. Respondents were asked about the likelihood of engaging in risky driving during the pandemic as compared to before COVID-19. Results show the majority of respondents indicated their behavior did not change, and most positively, a small proportion reported they were less likely to engage in these risky driving behaviors. However, notable proportions indicated they were more likely to engage in risky driving behaviors during the pandemic, as compared to before COVID-19. Of those who indicated this, U.S. drivers had significantly higher percentages compared to their Canadian counterparts. Behaviors most often reported by this sub-section of drivers who admit to being more likely to engage in risky driving during the pandemic were speeding (7.6%) and drinking and driving (7.6%) in the U.S., and speeding (5.5%) and distracted driving (4.2%) in Canada. Logistic regression results confirm that country was a significant factor, as U.S. drivers had greater odds of reporting they were more likely to engage in these risky driving behaviors, with the exception of speeding. Age also had a significant effect, as increasing age was associated with lower odds of reporting that these risky driving behaviors were more likely during the pandemic. Conversely, sex did not have a significant effect. Overall, the current findings suggest that a small proportion of drivers reported being more likely to engage in risky driving behaviors and the pandemic may have led to changes in the profiles of those drivers engaging in risky driving behaviors during lockdown measures. These results have important implications for policies and can inform how to manage road safety during future lockdowns.

A Roadmap to the Structure-Related Metabolism Pathways of Per- and Polyfluoroalkyl Substances in the Early Life Stages of Zebrafish (Danio rerio)

BACKGROUND

Thousands of per- and polyfluoroalkyl substances (PFAS) with diverse structures have been detected in the ambient environment. Apart from a few well-studied PFAS, the structure-related toxicokinetics of a broader set of PFAS remain unclear.

OBJECTIVES

To understand the toxicokinetics of PFAS, we attempted to characterize the metabolism pathways of 74 structurally diverse PFAS samples from the U.S. Environmental Protection Agency's PFAS screening library.

METHODS

Using the early life stages of zebrafish (Danio rerio) as a model, we determined the bioconcentration factors and phenotypic toxicities of 74 PFAS. Then, we applied high-resolution mass spectrometry-based nontargeted analysis to identify metabolites of PFAS in zebrafish larvae after 5 d of exposure by incorporating retention time and mass spectra. In vitro enzymatic activity experiments with human recombinant liver carboxylesterase (hCES1) were employed to validate the structure-related hydrolysis of 11 selected PFAS.

RESULTS

Our findings identified five structural categories of PFAS prone to metabolism. The metabolism pathways of PFAS were highly related to their structures as exemplified by fluorotelomer alcohols that the predominance of β-oxidation or taurine conjugation pathways were primarily determined by the number of hydrocarbons. Hydrolysis was identified as a major metabolism pathway for diverse PFAS, and perfluoroalkyl carboxamides showed the highest in vivo hydrolysis rates, followed by carboxyesters and sulfonamides. The hydrolysis of PFAS was verified with recombinant hCES1, with strong substrate preferences toward perfluoroalkyl carboxamides.

CONCLUSIONS

We suggest that the roadmap of the structure-related metabolism pathways of PFAS established in this study would provide a starting point to inform the potential health risks of other PFAS. https://doi.org/10.1289/EHP7169.

Co-occurrence of antiseptic triclocarban and chiral anti-inflammatory ibuprofen in environment: Association between biological effect in sediment and risk to human health

Residues of antiseptics and drugs have been ubiquitously detected in aquatic water-sediment systems, and are thus considered emerging contaminants that threaten our global environment. To investigate the potential risk of ibuprofen and triclocarban in sediment, effects of enzyme activity on the enantioselective degradation in sediment were investigated. Enantioselective fate of rac-ibuprofen was observed in sediment with R-enantiomer exhibiting preferential degradation. Enzyme evidence showed that high levels of triclocarban could significantly inhibit activities of catalase and urease activities in sediment, as well as increase the half-life of ibuprofen (from 5.8 d to 10.1 d). Cytotoxicity data suggested that cell growth processes were significantly affected by ibuprofen and triclocarban co-exposure, which was consistent with apoptosis results. Additionally, the expression of several proteins (Cyto-c, Nrf2, p62, Keap1, NQO1, and Pink1) were markedly induced upon exposure to ibuprofen in the presence of triclocarban. In conclusion, these findings illustrated that co-occurrence of ibuprofen and triclocarban residues have synergistic adverse effects to the environment and synergistically threaten human health.

Suspect and Nontarget Screening Revealed Class-Specific Temporal Trends (2000-2017) of Poly- and Perfluoroalkyl Substances in St. Lawrence Beluga Whales

The global use of >3000 per- and polyfluoroalkyl substances (PFASs) has given rise to chemical regulatory action. However, limited information exists regarding current and historical emissions for the majority of PFASs under currently implemented regulations. This study employed suspect and nontarget screening to examine the temporal trends of legacy and unregulated PFASs in liver of the endangered beluga whale (Delphinapterus leucas) population from the St. Lawrence Estuary in Canada collected from 2000 to 2017. A suite of 54 PFASs were tentatively identified, and were grouped into nine structurally distinct classes. Single-hydrogenated perfluoro carboxylic acids (H-PFCAs), single-hydrogenated sulfonamides (H-Sulfonamides), as well as other select sulfonamides were detected for the first time in wildlife. Greater concentrations of the majority of PFASs were determined in newborns and juveniles than in adults, suggesting effective placental and lactational transfer of PFASs. Legacy per- and polyfluoroalkyl acids and perfluorooctane sulfonamide in beluga whale liver were found to significantly decrease in concentration between 2000 and 2017, while unregulated short-chain PFAS alternatives, H-PFCAs, and odd-chain FTCAs were found to increase over time. The implementation of suspect and nontarget screening revealed class-specific temporal trends of PFASs in SLE beluga whales, and supported continuous emissions of unregulated PFASs into the environment.

Nationwide Biomonitoring of Neonicotinoid Insecticides in Breast Milk and Health Risk Assessment to Nursing Infants in the Chinese Population

Presently, the potential health risks of neonicotinoid insecticides (neonics) are now receiving much attention, but no data regarding the exposure of infants to neonics via human breast milk intake have been reported. In this study, a nationwide survey was conducted during the period of 2017-2019, wherein 97 pooled breast milk samples were collected from 3570 lactating women of 23 provinces in China. Nationally, acetamiprid-N-desmethyl was the most predominant compound, accounting for 61.2% of the total amount of neonics, followed by imidacloprid (15.6%). The concentration of the sum of acetamiprid and its metabolite acetamiprid-N-desmethyl in breast milk was positively correlated with corresponding dietary exposure, while no statistically significant association between the other neonic levels in breast milk and dietary exposure was found. The cumulative daily intakes of neonics (9.40-249 ng kg^-1 of body weight day^-1) were estimated for breastfed infants, indicating a minuscule risk to Chinese infants from neonic exposure via breastfeeding.

How microplastics affect chiral illicit drug methamphetamine in aquatic food chain? From green alga (Chlorella pyrenoidosa) to freshwater snail (Cipangopaludian cathayensis)

The biological impacts of microplastics on many organisms have been well documented. However, the combined effects of microplastics and chiral chemicals on the aquatic food chain are less clear. In the present study, the enantioselective environmental behaviors of methamphetamine co-exposed with microplastics through an aquatic food chain (from Chlorella pyrenoidosa to Cipangopaludian cathayensis) have been investigated in a laboratory environment. It was found that the acute toxicity of methamphetamine against these two species was significantly increased in the presence of microplastics: Chlorella pyrenoidosa showed an EC₅₀ shift from 0.77 to 0.32 mg L^-1, while cipangopaludian cathayensis showed an LC₅₀ shift from 4.15 to 1.48 mg L^-1, upon the addition of microplastics as a co-contaminant with methamphetamine. Upon exposure to methamphetamine and microplastics, the oxidative damage of algae (19.9 to 36.8 nmol mgprot^-1), apoptosis (increase about 2.17 times) and filtration rate (41.2 to 65.4 mL h^-1) of snails were observably higher when compared to exposure to methamphetamine alone. After ingestion and accumulation of microplastics, the enantioselectivity, BCFs, BMFs, and distribution of methamphetamine were significantly altered. These results provide evidence that the co-occurrence of microplastics and the chiral drug methamphetamine may increase the burden on aquatic species, with potential further impacts throughout aquatic food chain.

Selective hydrophilic modification of Parylene C films: a new approach to cell micro-patterning for synthetic biology applications

We demonstrate a simple, accurate and versatile method to manipulate Parylene C, a material widely known for its high biocompatibility, and transform it to a substrate that can effectively control the cellular microenvironment and consequently affect the morphology and function of the cells in vitro. The Parylene C scaffolds are fabricated by selectively increasing the material's surface water affinity through lithography and oxygen plasma treatment, providing free bonds for attachment of hydrophilic biomolecules. The micro-engineered constructs were tested as culture scaffolds for rat ventricular fibroblasts and neonatal myocytes (NRVM), toward modeling the unique anisotropic architecture of native cardiac tissue. The scaffolds induced the patterning of extracellular matrix compounds and therefore of the cells, which demonstrated substantial alignment compared to typical unstructured cultures. Ca(2+) cycling properties of the NRVM measured at rates of stimulation 0.5-2 Hz were significantly modified with a shorter time to peak and time to 90% decay, and a larger fluorescence amplitude (p < 0.001). The proposed technique is compatible with standard cell culturing protocols and exhibits long-term pattern durability. Moreover, it allows the integration of monitoring modalities into the micro-engineered substrates for a comprehensive interrogation of physiological parameters.

Development of core competencies for an international training programme in intensive care medicine

OBJECTIVE

The aim of this study was to define the core (minimum) competencies required of a specialist in adult intensive care medicine (ICM). This is the second phase of a 3-year project to develop an internationally acceptable competency-based training programme in ICM for Europe (CoBaTrICE).

METHODOLOGY

Consensus techniques (modified Delphi and nominal group) were used to enable interested stakeholders (health care professionals, educators, patients and their relatives) to identify and prioritise core competencies. Online and postal surveys were used to generate ideas. A nominal group of 12 clinicians met in plenary session to rate the importance of the competence statements constructed from these suggestions. All materials were presented online for a second round Delphi prior to iterative editorial review.

RESULTS

The initial surveys generated over 5,250 suggestions for competencies from 57 countries. Preliminary editing permitted us to encapsulate these suggestions within 164 competence stems and 5 behavioural themes. For each of these items the nominal group selected the minimum level of expertise required of a safe practitioner at the end of their specialist training, before rating them for importance. Individuals and groups from 29 countries commented on the nominal group output; this informed the editorial review. These combined processes resulted in 102 competence statements, divided into 12 domains.

CONCLUSION

Using consensus techniques we have generated core competencies which are internationally applicable but still able to accommodate local requirements. This provides the foundation upon which an international competency based training programme for intensive care medicine can be built.

An international survey of training in adult intensive care medicine

OBJECTIVE

The aim of this international survey of training in adult intensive care medicine (ICM) was to characterise current structures, processes, and outcomes to determine the potential for convergence to a common competency-based training programme across national borders. This survey is the first phase of a 3 year project which will use consensus methods to build an international competency-based training programme in ICM in Europe (CoBaTrICE).

METHODOLOGY

A survey by questionnaire, e-mail, and direct discussion was undertaken with national ICM representatives from seven geographical regions.

RESULTS

Responses were obtained from 41 countries (countries which share common training programmes were grouped together; n=38). Fifty-four different training programmes were identified, 37 within the European region; three (6%) were competency-based. Twenty (53%) permitted multidisciplinary access to a common training programme; in nine (24%) training was only available within anaesthesia. The minimum duration of ICM training required for recognition as a specialist varied from 3 months to 72 months (mode 24 months). The content of most (75%) ICM programmes was standardised nationally. Work-based assessment of competence was formally documented in nineteen (50%) countries. An exam was mandatory in twenty-nine (76%).

CONCLUSION

There are considerable variations in the structures and processes of ICM training worldwide. However, as competency-based training is an outcome strategy rather than a didactic process, these differences should not impede the development of a common international competency-based training programme in ICM.

279. A dynamic model of the control of pulsatile luteinizing hormone secretion by gonadotrophin-releasing hormone

Infusion of GnRH in a continuous manner or with a very high pulse frequency initially stimulates but then downregulates LH secretion.1,2 This phenomenon is caused by the slow rate of internalisation of the GnRH receptor (GnRH-R) and the subsequent slow return of receptors to the plasma membrane of the gonadotroph.3 Pulsatile release of GnRH overcomes this problem by allowing a delay between successive stimulations. It is difficult to determine the relative importance of critical control points in this process in an animal model because GnRH activity reflects integrated inputs from many internal and external factors. We are therefore using SAAM II software to develop a compartmental model of the relationship between GnRH-R availability and LH responses following changes in GnRH pulse frequency. The model has three receptor states (free, bound, and internalised) and one LH compartment (Fig. 1). We assumed LH release is a function of the amount of receptor that binds GnRH. Following GnRH binding, receptors are rapidly lost as they enter the internalised state and then slowly returned to the membrane surface. We further assumed that the slow rate of receptor return explains the decrease in LH response with very high frequencies of GnRH pulses. The values for parameters were based on data obtained from experiments with sheep. In our current version of the model, downregulation is observed when gonadotrophs are stimulated with GnRH pulses every 15 min (Fig. 1), but not with pulses every 30 or 60 min, at a slow recycling rate (0.004 min–1). In contrast, LH secretion increases when GnRH is pulsed every 15 min and recycling rate is increased to 0.04 min–1. This suggests that, in sheep, a recycling rate between 0.004 and 0.04 min–1 is a critical aspect of the intracellular control of the process. Future work will include steroid feedback loops.

Evaluation of Podophyllum peltatum accessions for podophyllotoxin production

In an effort to develop a sustainable source of podophyllotoxin for the production of anticancer drugs such as etoposide, teniposide and etopophos, Podophyllum peltatum accessions with podophyllotoxin-rich leaf biomass were identified and transplanted to different growing conditions by vegetative cuttings. Results indicate that the lignan profile in leaves does not change over time or due to environment conditions. Podophyllotoxin and alpha-peltatin content in the blades seems to be stable with an inverse relationship of concentration between these compounds. A podophyllotoxin-rich leaf accession showed low biosynthetic capability to synthesize alpha- and beta-peltatin and the converse was also true, indicating that selection and cultivation of high-yielding podophyllotoxin leaf biomass may reduce production costs.

Metabolic modes of action of the statins in the hyperlipoproteinemias

Conflicting results have been published during the past few years regarding the physiologic modes of action of the hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors, generally referred to as statins, using standard doses. Three mechanisms have been described: increased LDL catabolic rate, increased removal of LDL precursors resulting in decreased LDL production and decreased VLDL production. The physiologic effects of statins seem to depend on the underlying pathology of the disorders under therapy. More recent data using either the more potent atorvastatin or larger doses of previously available statins (e.g. simvastatin 80-160 mg/day), suggest that both the potency of the statins and the underlying pathopHysiology are important in determining the predominant physiologic responses of patients. To understand physiologic responses more completely, drug-dose-physiologic response curves of apo B kinetics in various groups of patients are needed. Simultaneous studies of apo B, triglycerides and cholesterol metabolism are also needed and are currently feasible.

Production rate determines plasma concentration of large high density lipoprotein in non-human primates

Large LpAI HDL particles, containing only apoA-I without apoA-II, are reported to be the major anti-atherogenic portion of HDL and to be increased in individuals with low risk for coronary heart disease. To determine whether the plasma concentration of large LpAI is modulated by the rate of production or catabolism of apolipoprotein A-I (apoA-I) in large LpAI, kinetic studies of large LpAI were performed in African green monkeys consuming an atherogenic diet with either high plasma HDL concentration (120 +/- 36 mg/dl, mean +/- SD, n = 3) or low plasma HDL concentration (40 +/- 13 mg/dl, n = 3). Large LpAI was isolated, without ultracentrifugation, by immunoaffinity and gel filtration and radiolabeled. After injection, the specific activity of apoA-I in large HDL, consisting of both LpAI and LpAI:AII particles, was followed. A multicompartmental model was developed for the kinetics of apoA-I in large HDL, which indicated that a portion of large HDL is distributed to a sequestered pool, outside the circulating plasma, and reenters circulating plasma approximately 3 h after injection. There was no conversion of large LpAI to smaller HDL particles or transfer of radiolabeled apoA-I to smaller HDL particles. Although the mean fractional catabolic rate was not different comparing the high and low HDL group, the mean production rate of apoA-I in large HDL was 4-fold greater in the high HDL group compared with the low HDL group. These data support the hypothesis that the plasma concentration of large HDL is controlled primarily by the rate of production of apoA-I in large HDL.

Bounds on null functions of linear digital imaging systems

Any linear digital imaging system produces a finite amount of data from a continuous object. This means that there are always null functions, so a reconstruction of the object, even without noise in the system, will differ from the actual object. With positivity constraints, the size of a null function is limited, provided that size is measured by the integral of the absolute value of the null function. When smoothing is used in reconstruction, then smoothed null functions become relevant. There are bounds on various measures of the size of smoothed null functions, and these bounds can be quite small. Smoothing will decrease the effects of null functions in object reconstructions, and this effect is greater if the smoothing operator is well matched to the system operator.

Symmetry properties of an imaging system and consistency conditions in image space

A general definition for a symmetry group of an imaging system is given. A key requirement is that the operators that represent the symmetries in data space are conformal. The result is that the space of consistency conditions is invariant under the action of the given symmetry group. Via the theory of group representations, this fact provides information about the possible forms that these consistency conditions can take. The theory is illustrated by example for the 2D and 3D Radon transforms, the cone-beam transform on a circular orbit and the 2D attenuated Radon transform.

Decomposition of images and objects into measurement and null components

We derive and discuss an algorithm for separating measurement-and null-space components of an object with respect to a given imaging system. This algorithm requires a discrete-to-discrete approximation of a typically continuous-to-discrete imaging system, and problems associated with such an approximation are examined. Situations where knowledge of the measurement and null spaces is crucial for analyzing imaging systems are discussed. We conclude with two examples demonstrating the usefulness of this algorithm, even in the discrete-to-discrete approximation.

Introduction

This issue of Optics Express provides a snapshot of current theoretical research in the area of tomographic image reconstruction. The topics have been chosen to illustrate some important principles that arise not only in medical imaging but also in the broader arena of indirect imaging. All of the papers were invited by the editors, and all underwent independent peer review.

How young children cope with separation: toward a new conceptualization

In this paper, it is argued that 'separation protest' and the protest-despair-detachment (PDD) pattern, having passed into folklore and become an almost undebated cornerstone in the literature on separation and attachment, continue to have a potent influence which needs to be reexamined, disputed and replaced. Three arguments are advanced: first, that the evidence for the PDD pattern was never substantial; second, that there is now and has for some time been ample evidence for alternative accounts of separation responses; third, that the PDD account, being premised on a model of the very young child as far less socially competent than recent research has indicated, stands in need of refinement.

A bound on null functions for digital imaging systems with positivity constraints

There is an upper bound for the L(1) norm of the difference of two nonnegative object functions when they both produce the same data in a digital imaging system. This bound is achieved for a certain class of systems and an arbitrary nonnegative object. For the L(2) norm of the difference, with the same conditions on the object functions, there is no upper bound.

Plasma kinetics of cholesteryl ester transfer protein in the rabbit. Effects of dietary cholesterol

The plasma kinetics of recombinant human cholesteryl ester transfer protein (rCETP) were studied in six rabbits before and after cholesterol feeding (0.5% wt/wt). The rCETP, labeled with the use of the Bolton Hunter reagent, was shown to retain neutral lipid transfer activity. After intravenous infusion, labeled rCETP associated with rabbit lipoproteins to an extent similar to endogenous rabbit CETP (62% to 64% HDL associated). The plasma kinetics of CETP, modeled with the use of SAAM-II, conformed to a two-pool model, likely representing free and loosely HDL-associated CETP (fast pool) and a tightly apo (apolipoprotein) AI-associated (slow pool) CETP. The plasma residency time (chow diet) of the fast pool averaged 7.1 hours and of the slow pool, 76.3 hours. The production rate (PR) into and the fractional catabolic rate (FCR) of the fast pool were 20 and 10 times the PR and FCR, respectively, of the slow pool. In response to cholesterol feeding, CETP PR, FCR, and plasma mass increased by 416%, 60%, and 230%, respectively. There was a strong correlation (r = .95, P = .003) between the increase in rabbit plasma CETP and the modeled increase in CETP PR in response to cholesterol feeding, suggesting that labeled human rCETP is a satisfactory tracer for rabbit plasma CETP. CETP is catabolized by distinct pools, likely corresponding to an apo AI-associated (slow) pool and a free and/or loosely HDL-associated (fast) pool. Factors that alter the affinity of CETP for HDL would be predicted to result in altered CETP catabolism. The effect of dietary cholesterol on plasma CETP mass can be explained largely by the effects on CETP synthesis, consistent with the observed effects of cholesterol on tissue mRNA levels.

Health, hygiene and maternal education: evidence from The Gambia

The paper explores the ways in which women's education influences domestic hygiene practices and use of health care services in a traditional agricultural village in The Gambia. The "environment of health" is one of poverty, high morbidity and low levels of female literacy. A detailed household survey was undertaken in the rainy season when agricultural work is demanding of people's time and energy and morbidity rates are high. Mothers with and without formal education and with at least one child under 5 were included in the study. Small differences were found between the educated and uneducated group in the knowledge and practice of household hygiene. The healthcare services in the village were utilised by all women regardless of whether or not they had been to school, but educated mothers appeared to have a better understanding of health education messages. The case study illustrates the synergy between health, hygiene and maternal education and discusses the implications of the findings.

Reduction of virus shedding by B. bifidum in experimentally induced MRV infection. Statistical application for ELISA

The protective effect of a human strain of Bifidobacterium bifidum (B. bifidum) against murine group A rotavirus (MRV) was examined in the intestines of BALB/c infected mice. In experiments designed to determine whether B. bifidum mediated MRV shedding during diarrheal disease, pregnant dams (and their expected litters) were randomly assigned to the following groups: (1) mice infected with MRV alone; (2) B. bifidum-treated + MRV-infected mice; (3) B. bifidum-treated controls; and (4) saline control animals. An enzyme-linked immunosorbent assay (ELISA) for the detection of group A rotavirus was used to measure virus protein. The sensitivity of the MRV antigen detector ELISA was determined by serially diluting the rotavirus antigen in test samples. Antigen was detected in dilution ranges of 1:256-1:4096 during the acute phase and 1:16-1:512 in the recovery phase of MRV clinical disease, in the samples tested. Treatment with B. bifidum significantly reduced shedding of MRV antigen (P < 0.009) on days 2-10 postinoculation. The reduction in shedding of virus protein corresponded well with delayed onset of acute diarrhea (P < 0.02). Closer examination of tissue cross sections under electron microscopy revealed that the B. bifidum-ingested strain adhered to the epithelium of the small intestine. These results suggest that priming the intestine with B. bifidum is effective against experimental MRV challenge and confirmed the potential usefulness of this detector ELISA for studying the kinetics of group A rotavirus infection in animals and humans.