The role of carbon nanotube structure in their retention and pathogenicity in the pleural cavity

Carbon nanotubes (CNT) are hexagonal arrangements of carbon atoms built up to form fibres with diameters in the nanometre range but lengths which may extend up to hundreds of microns. The physiochemical properties of CNT are advantageous for a variety of industrial applications leading to CNT becoming one of the major products in the burgeoning field of nanotcchnology. However their structural similarity to asbestos has raised concerns that they may also pose an occupational inhalation hazard and cause diseases of the lung or pleura. Several decades of fibre toxicology have lead to the development of a robust structure/activity model, the fibre pathogenicity paradigm (FPP), which identifies length, thinness and biopersistence as the critical properties a fibrous particle must possess if it is to be pathogenic. The purpose of this study was to examine the pathogenicity of CNT in relation to the FPP by examining the effect of CNT in the pleural space, a target tissue for asbestosrelated disease.In order to address this aim a method of injection directly into the pleura cavity of mice was employed. Direct instillation of long and short CNT into the pleural cavity produced length-dependent responses characterized by acute inflammation leading to progressive fibrosis on the parietal pleura which mirrored the pleura response to asbestos. Furthermore examination of the size-restricted clearance mechanisms from the pleural cavity confirmed the hypothesis that the pathogenicity of long CNT and other fibres, arises as a result of length-dependent retention at the stomata on the parietal pleura.The cellular interactions leading to an inflammatory response in the pleural cavity were also examined in an in vitro study which tested the CNT for their ability to stimulate the release of the acute phase cytokines from both mesothelial cells and macrophages. Direct exposure to CNT resulted in significant cytokine release from the macrophages but not mesothelial cells. This pro-inflammatory response was length dependent but modest and was shown to be a function of frustrated phagocytosis. Furthermore the indirect actions of the CNT were examined by treating the mesothelial cells with conditioned media from CNT-treated macrophages. This resulted in dramatic amplification of cytokine release from the mesothelial cells. We therefore hypothesise that long fibres elicit an inflammatory response in the pleural cavity via frustrated phagocytosis in pleural macrophages. The activated macrophages then stimulate an amplified pro-inflammatory cytokine response from the adjacent pleural mesothelial cells.A further aim was to investigate the relationship between the length-dependent pathogenicity of a fibre sample and the surface of the fibre. By using different forms of functional groups attached to the surface of a pathogenic CNT we tested if the level of inflammation and fibrosis triggered in vivo can be altered by simple alteration of the surface. Our results showed that, although the surface modification of CNT did not alter the acute inflammogenicity of the CNT, the chronic fibrotic response was significantly attenuated. The specific role surface chemistry played in the modification of the CNT pathogenicity however was obfuscated by the apparent lack of biopersistcncc of the functionalised CNT compared with the pristine sample.Although direct injection into the pleural space is a convenient model to assess the hazard of fibres to the mesothelium it is not a physiologically relevant route by which workers may be exposed to CNT. Therefore we examined the inflammatory potential of CNT on the lungs and pleural cavity following pharyngeal aspiration into the airspaces. A length-dependent inflammatory response in the lungs was observed where only the long CNT sample caused acute neutrophilic inflammation at one week and progressive interstitial thickening of the alveolar septa by six weeks post exposure. Furthermore we report the induction of a length-dependent inflammatory response in the pleural cavity after exposure to CNT via the lung airspaces with concomitant evidence for the translocation of CNT from the lung into in the pleural cavity and subsequent retention along the parietal pleura.In summary the results presented here demonstrate the length-dependent pathogenicity of CNT in the pleural cavity and highlights the necessity for risk assessment for people likely to be exposed in the workplace. We also explored mechanistic aspects of the inflammatory response to long CNT which has implications for the general understanding of fibre-related pleural disease and may prove useful for the design of safe nanofibres

Coping and Help in Birth: An investigation into ‘normal’ childbirth as described by new mothers and their attending midwives

peer-reviewedObjective: to investigate how 'normal' childbirth is described by new mothers and their attending midwives.Design: a qualitative, reflexive, narrative study was used to explore birth stories using in-depth, unstructured interviews.Setting: 21 new mothers and their 16 attending midwives were recruited from the locality surrounding a district general hospital in South Wales, United Kingdom (UK).Findings: the findings identified that the mothers wanted to cope with labour and birth, by breathing through it and using some birth interventions with the help of knowledgeable midwives. Midwives aimed to achieve 'normality' in birth but also commonly utilised birth interventions. Consequently the notion of 'normal' birth as not involving interventions in birth was not found to be a useful defining concept in this study. Furthermore, current dichotomous models and theories of birth and midwifery in particular those relating to pain management did not fully explain the perspectives of these women and their midwives.Implications for practice: dichotomous models and theories for birth and midwifery practice and those which incorporate the term 'normal' birth are shown to be not entirely useful to fully explain the contemporary complexity of childbirth in the UK. Therefore it is now necessary to consider avoiding using dichotomous models of birth and midwifery in the UK and to instead concentrate on developing integrated models that reflect the real life current experiences of women and their midwives. (C) 2016 Elsevier Ltd. All rights reserved.ACCEPTEDpeer-reviewe

The mechanism of pleural inflammation by long carbon nanotubes: interaction of long fibres with macrophages stimulates them to amplify pro-inflammatory responses in mesothelial cells

Carbon nanotubes (CNT) are high aspect ratio nanoparticles with diameters in the nanometre range but lengths extending up to hundreds of microns. The structural similarities between CNT and asbestos have raised concern that they may pose a similar inhalation hazard. Recently CNT have been shown to elicit a length-dependent, asbestos-like inflammatory response in the pleural cavity of mice, where long fibres caused inflammation but short fibres did not. However the cellular mechanisms governing this response have yet to be elucidated. This study examined the in vitro effects of a range of CNT for their ability to stimulate the release of the acute phase cytokines; IL-1β, TNFα, IL-6 and the chemokine, IL-8 from both Met5a mesothelial cells and THP-1 macrophages. Results showed that direct exposure to CNT resulted in significant cytokine release from the macrophages but not mesothelial cells. This pro-inflammatory response was length dependent but modest and was shown to be a result of frustrated phagocytosis. Furthermore the indirect actions of the CNT were examined by treating the mesothelial cells with conditioned media from CNT-treated macrophages. This resulted in a dramatic amplification of the cytokine release from the mesothelial cells, a response which could be attenuated by inhibition of phagocytosis during the initial macrophage CNT treatments. We therefore hypothesise that long fibres elicit an inflammatory response in the pleural cavity via frustrated phagocytosis in pleural macrophages. The activated macrophages then stimulate an amplified pro-inflammatory cytokine response from the adjacent pleural mesothelial cells. This mechanism for producing a pro-inflammatory environment in the pleural space exposed to long CNT has implications for the general understanding of fibre-related pleural disease and design of safe nanofibres

Asbestos, carbon nanotubes and the pleural mesothelium: a review of the hypothesis regarding the role of long fibre retention in the parietal pleura, inflammation and mesothelioma

The unique hazard posed to the pleural mesothelium by asbestos has engendered concern in potential for a similar risk from high aspect ratio nanoparticles (HARN) such as carbon nanotubes. In the course of studying the potential impact of HARN on the pleura we have utilised the existing hypothesis regarding the role of the parietal pleura in the response to long fibres. This review seeks to synthesise our new data with multi-walled carbon nanotubes (CNT) with that hypothesis for the behaviour of long fibres in the lung and their retention in the parietal pleura leading to the initiation of inflammation and pleural pathology such as mesothelioma. We describe evidence that a fraction of all deposited particles reach the pleura and that a mechanism of particle clearance from the pleura exits, through stomata in the parietal pleura. We suggest that these stomata are the site of retention of long fibres which cannot negotiate them leading to inflammation and pleural pathology including mesothelioma. We cite thoracoscopic data to support the contention, as would be anticipated from the preceding, that the parietal pleura is the site of origin of pleural mesothelioma. This mechanism, if it finds support, has important implications for future research into the mesothelioma hazard from HARN and also for our current view of the origins of asbestos-initiated pleural mesothelioma and the common use of lung parenchymal asbestos fibre burden as a correlate of this tumour, which actually arises in the parietal pleura

Reproductive Failure in UK Harbour Porpoises Phocoena phocoena : Legacy of Pollutant Exposure?

This research was supported by a Marie Curie International Outgoing Fellowship within the Seventh European Community Framework Programme (Project Cetacean-stressors, PIOF-GA-2010-276145 to PDJ and SM). Additional funding was provided through the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS) (Grants SSFA/2008 and SSFA / ASCOBANS / 2010 / 5 to SM). Analysis of Scottish reproductive and teeth samples was funded by the EC-funded BIOCET project (BIOaccumulation of persistent organic pollutants in small CETaceans in European waters: transport pathways and impact on reproduction, grant EVK3-2000-00027 to GJP), and Marine Scotland (GJP). Samples examined in this research were collected under the collaborative Cetacean Strandings Investigation Programme (http://ukstrandings.org/), which is funded by the Department for Environment, Food and Rural Affairs (Defra) and the UK’s Devolved Administrations in Scotland and Wales (http://sciencesearch.defra.gov.uk/Defaul​t.aspx?Menu=Menu&Module=More&Location=No​ne&Completed=0&ProjectID=15331) (grants to PDJ, RD). UK Defra also funded the chemical analysis under a service-level agreement with the Centre for Environment, Fisheries and Aquaculture Science (grants to RJL, JB). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Fisheries interactions of Delphinus delphis in the north-east Atlantic with an emphasis on Galicia, north-west Spain.

Bycatch from interactions with fisherie s remains the biggest global threat to marine mammals. Galicia, north - west Spain, is one of the world’s main fishing regions and a high level of cetacean - fisheries interactions has been reported from on - board observers, interviews with fisheries stakeholde rs and analysis of stranded and by - caught carcasses. Delphinus delphis is the most abundant cetacean in the area and since 1990 necropsies of over 1800 stranded and by - caught Delphinus have been conducted. Life history data (age, maturity, and pregnancy ra te data) from stranded and by - caught cetaceans can be used to construct life tables and to estimate overall mortality and fisheries mortality rates. Age and maturity were determined from stranded and by - caught Delphinus between 1990 and 2009. Males and fem ales reach sexual maturity at 8.5 and 7.5 years of age, respectively, and no temporal difference in age at sexual maturity was observed. Results indicate 13% annual mortality in the Delphinus delphis north - east Atlantic population and necropsy data suggest s that 60% of mortality (i.e. 7.2% annual mortality) is attributable to fisheries interactions, predominantly from pair trawls and gillnets. By - caught Delphinus were found to die significantly younger than non - by - caught animals (p=<0.001) although no sex - r elated difference in bycatch rate was observed (p=0.051). The estimated annual mortality due to fisheries interactions greatly exceeds the 2% limit set by ASCOBANS and the IWC and high bycatch rates are also reported for other countries e.g. the UK, France and Portugal. Although Delphinus delphis in the north - east Atlantic is one continuous population, the high level of bycatch occurring in parts of the range is most likely unsustainable and will be discussed. There is a need to carry out on - board monitorin g, notably in the north - west Iberian Peninsula (Galicia and Portugal), to incorporate cetacean bycatch into fisheries advice and, above all, to start introducing mitigation measures

Vascular smooth muscle cells enhance immune/vascular interplay in a 3-cell model of vascular inflammation

Atherosclerosis is a serious cardiovascular disease that is characterised by the development of atheroma, which are lipid-laden plaques that build up within arterial walls due to chronic inflammatory processes. These lesions are fundamentally attributed to a complex cellular crosstalk between vascular smooth muscle cells (VSMCs), vascular endothelial cells (VECs) and central immune cells, such as macrophages (Mɸs), which promote vascular inflammation. The presence of VSMCs exerts both positive and negative effects during atheroma development, which can be attributed to their phenotypic plasticity. Understanding the interactions between these key cell types during the development of vascular inflammation and atheroma will enhance the scope for new therapeutic interventions. This study aims to determine the importance of VSMCs for shaping the extracellular cytokine/chemokine profile and transcriptional responses of VECs (human coronary artery endothelial cells; HCAECs) to activated lipopolysaccharide (LPS)-stimulated THP1 Mɸs, in a 3-cell model of human vascular inflammation. It is evident that within the presence of VSMCs, enhanced cytokine production was associated with up-regulation of genes associated with vascular inflammation t. Results demonstrate that the presence of VSMCs in co-culture experiments enhanced cytokine production (including CXCL1/GROα, IL-6, IL-8 and CCL2/MCP1) and inflammatory gene expression (including genes involved in JAK/STAT, Jun and NFκB signalling) in HCAECs co-cultured with LPS-stimulated THP1 Mɸs. Our results highlight the importance of VSMCs in immune/endothelial cell interplay and indicate that 3-cell, rather than 2-cell co-culture, may be more appropriate for the study of cellular crosstalk between immune and vascular compartments in response to inflammatory and atherogenic stimuli

A method to assess the relevance of nanomaterial dissolution during reactivity testing

The reactivity of particle surfaces can be used as a criterion to group nanoforms (NFs) based on similar potential hazard. Since NFs may partially or completely dissolve over the duration of the assays, with the ions themselves inducing a response, reactivity assays commonly measure the additive reactivity of the particles and ions combined. Here, we determine the concentration of ions released over the course of particle testing, and determine the relative contributions of the released ions to the total reactivity measured. We differentiate three classes of reactivity, defined as being A) dominated by particles, B) additive of particles and ions, or C) dominated by ions. We provide examples for each class by analyzing the NF reactivity of Fe2O3, ZnO, CuO, Ag using the ferric reduction ability of serum (FRAS) assay. Furthermore, another two reactivity tests were performed: Dichlorodihydrofluorescin diacetate (DCFH2‑DA) assay and electron paramagnetic resonance (EPR) spectroscopy. We compare assays and demonstrate that the dose‑response may be almost entirely assigned to ions in one assay (CuO in DCFH2‑DA), but to particles in others (CuO in EPR and FRAS). When considering this data, we conclude that one cannot specify the contribution of ions to NF toxicity for a certain NF, but only for a certain NF in a specific assay, medium and dose. The extent of dissolution depends on the buffer used, particle concentration applied, and duration of exposure. This culminates in the DCFH2‑DA, EPR, FRAS assays being performed under different ion‑to‑particle ratios, and differing in their sensitivity towards reactions induced by either ions or particles. If applied for grouping, read‑across, or other concepts based on the similarity of partially soluble NFs, results on reactivity should only be compared if measured by the same assay, incubation time, and dose range