Trace metals associated with nanoparticles are known to possess reactivities that are different from their larger-size counterparts. However, the relative importance of small relative to large ...particles for the overall distribution and biouptake of these metals is not as well studied in complex environmental systems. Here, we have examined differences in the long term fate and transport of ceria (CeO2) nanoparticles of two different sizes (3.8 vs 185 nm), dosed weekly to freshwater wetland mesocosms over 9 months. While the majority of CeO2 particles were detected in soils and sediments at the end of nine months, there were significant differences observed in fate, distribution, and transport mechanisms between the two materials. Small nanoparticles were removed from the water column primarily through heteroaggregation with suspended solids and plants, while large nanoparticles were removed primarily by sedimentation. A greater fraction of small particles remained in the upper floc layers of sediment relative to the large particles (31% vs 7%). Cerium from the small particles were also significantly more bioavailable to aquatic plants (2% vs 0.5%), snails (44 vs 2.6 ng), and insects (8 vs 0.07 μg). Small CeO2 particles were also significantly reduced from Ce(IV) to Ce(III), while aquatic sediments were a sink for untransformed large nanoparticles. These results demonstrate that trace metals originating from nanoscale materials have much greater potential than their larger counterparts to distribute throughout multiple compartments of a complex aquatic ecosystem and contribute to the overall bioavailable pool of the metal for biouptake and trophic transfer.
Abstract
Confirmation of cannabinoid use by forensic toxicology testing in urine has been traditionally focused on ∆9-tetrahydrocannabinol (∆9-THC) with analysis of its major metabolite, ...11-nor-9-carboxy-∆9-THC (∆9-cTHC), in free and conjugated forms. Legalization of hemp, however, has led to the widespread production and sale of cannabidiol (CBD) derivatives with psycho-activity, including ∆8-THC and ∆10-THC isomers. The increasing availability and growing use of isomer derivatives necessitate an expanded scope of cannabinoid confirmation test protocols. We report a quantitative, isomer-selective method of cannabinoid confirmation by liquid chromatography–tandem mass spectrometry determination of parent drug isomers (∆8-THC, ∆9-THC, ∆10-THC and CBD) as well as isomeric metabolites (∆8-cTHC and ∆9-cTHC). An efficient C18 phase chromatography on 1.6-µm solid core particles was used with a step gradient for near isocratic separation of both early-eluting THC metabolite isomers and later-eluting CBD and THC isomers. A rapid method of hydrolysis, dilution and analysis was employed for the quantitative co-determination of free and conjugated analytes, using stable isotope internal standardization. Method validation is reported, along with interference assessment from a prior confirmation method. Casework experience with the isomer-selective method revealed a 14% prevalence of ∆8-cTHC positive cases with a pattern of concomitant ∆8-THC and ∆9-THC use. A comparison of ∆8-cTHC and ∆9-cTHC phase two metabolism is also reported.
The interneuronal propagation of aggregated tau is believed to play an important role in the pathogenesis of human tauopathies. It requires the uptake of seed-competent tau into cells, seeding of ...soluble tau in recipient neurons and release of seeded tau into the extracellular space to complete the cycle. At present, it is not known which tau species are seed-competent. Here, we have dissected the molecular characteristics of seed-competent tau species from the TgP301S tau mouse model using various biochemical techniques and assessed their seeding ability in cell and animal models. We found that sucrose gradient fractions from brain lysates seeded cellular tau aggregation only when large (>10 mer) aggregated, hyperphosphorylated (AT8- and AT100-positive) and nitrated tau was present. In contrast, there was no detectable seeding by fractions containing small, oligomeric (<6 mer) tau. Immunodepletion of the large aggregated AT8-positive tau strongly reduced seeding; moreover, fractions containing these species initiated the formation and spreading of filamentous tau pathology in vivo, whereas fractions containing tau monomers and small oligomeric assemblies did not. By electron microscopy, seed-competent sucrose gradient fractions contained aggregated tau species ranging from ring-like structures to small filaments. Together, these findings indicate that a range of filamentous tau aggregates are the major species that underlie the spreading of tau pathology in the P301S transgenic model. Significance statement: The spread of tau pathology from neuron to neuron is postulated to account for, or at least to contribute to, the overall propagation of tau pathology during the development of human tauopathies including Alzheimer's disease. It is therefore important to characterize the native tau species responsible for this process of seeding and pathology spreading. Here, we use several biochemical techniques to dissect the molecular characteristics of native tau protein conformers from TgP301S tau mice and show that seed-competent tau species comprise small fibrils capable of seeding tau pathology in cell and animal models. Characterization of seed-competent tau gives insight into disease mechanisms and therapeutic interventions.
Reliable predictions of the environmental fate and risk of engineered nanomaterials (ENMs) require a better understanding of ENM reactivity in complex, biologically active systems for chronic ...low-concentration exposure scenarios. Here, simulated freshwater wetland mesocosms were dosed with ENMs to assess how their reactivity and seasonal changes in environmental parameters influence ENM fate in aquatic systems. Copper-based ENMs (Kocide), known to dissolve in water, and gold nanoparticles (AuNPs), stable against dissolution in the absence of specific ligands, were added weekly to mesocosm waters for 9 months. Metal accumulation and speciation changes in the different environmental compartments were assessed over time. Copper from Kocide rapidly dissolved likely associating with organic matter in the water column, transported to terrestrial soils and deeper sediment where it became associated with organic or sulfide phases. In contrast, Au accumulated on/in the macrophytes where it oxidized and transferred over time to surficial sediment. A dynamic seasonal accumulation and metal redox cycling were found between the macrophyte and the surficial sediment for AuNPs. These results demonstrate the need for experimental quantification of how the biological and chemical complexity of the environment, combined with their seasonal variations, drive the fate of metastable ENMs.
Racism and industrial development across lands and waters in the province of Ontario have played a significant role in decreased access to traditional food for Indigenous peoples. Traditional food ...access is important for health reasons, as well as cultural and spiritual wellness, and its loss has dire consequences for both people and the environment. In this commentary, we bring together our practices and experiences as settler Canadians in the fields of environmental law and environmental studies to share three short case studies exploring the linkages among traditional food access, racism, and industrial development. Specifically, we discuss how the aerial spraying of forests, mining exploration, and contaminants in fish are impacting traditional food access, and analyze how industry and monetary gains are drivers in these scenarios. For each of these case studies, we provide examples of research and advocacy from our respective fields carried out with Indigenous communities. We conclude by offering our insights for addressing systemic racism in food systems, focusing on a need for policy to prioritize Indigenous sovereignty and rights and opportunities for collaboration spanning different areas of practice and Western and Indigenous knowledge systems.
Le racisme et le développement industriel sur les terres et dans les eaux de l’Ontario ont joué un rôle considérable dans la diminution de l’accès à la nourriture traditionnelle pour les peuples autochtones. Or, cet accès est important pour des raisons de santé de même que pour le bien-être culturel et spirituel; cette perte a des conséquences désastreuses pour les personnes et pour l’environnement. Dans ce texte, nous réunissons nos expériences et nos pratiques en tant que personnes canadiennes allochtones dans les champs du droit de l’environnement et des études environnementales pour partager trois courtes études de cas qui explorent les liens entre l’accès à la nourriture traditionnelle, le racisme et le développement industriel. Plus précisément, nous discutons les répercussions de la pulvérisation aérienne des forêts, de l’exploration minière et de la contamination des poissons sur l’accès à la nourriture traditionnelle, et nous analysons comment l’industrie et l’appât du gain sont en cause dans ces scénarios. Pour chacune de ces études de cas, nous fournissons des exemples de recherche et d’argumentation menées avec des communautés autochtones dans nos champs respectifs. Nous concluons avec nos suggestions sur la manière de s’attaquer au racisme systémique dans les systèmes alimentaires, en se concentrant sur la nécessité d’instaurer des politiques qui mettent de l’avant la souveraineté et les droits des Autochtones, en plus de susciter la collaboration entre différents domaines de pratique et entre les systèmes de savoir occidentaux et autochtones.
Clostridioides difficile infection (CDI) is an issue of great concern due to its rising incidence, recurrence, morbidity and impact on healthcare spending. Treatment guidelines have changed in the ...last few years, and new therapies are being considered. This is a practical review for the primary care practitioner of the latest guidelines for CDI diagnosis, treatment, and emerging therapies.
Disordered eating and difficulties with emotion regulation have shown strong associations but there has been little attention paid to possible mediators that would explain this relationship. In ...depression and anxiety, negative memory and interpretation biases are implicated in the onset and maintenance of these disorders, however, little is known about whether these biases also exist in eating disorders, and if they are related to difficulties with emotion regulation. Females (
n
= 181) aged 17–26 years, completed self-report measures of disordered eating and behaviours, difficulties in emotion regulation, depression, anxiety, and memory and interpretation bias. While negative memory bias was related to objective binge episodes, it was not related to difficulties in emotion regulation. Negative interpretation biases were associated with higher levels of eating psychopathology and objective binge eating when controlling for depression and anxiety. Cross-sectional testing showed this bias to mediate the relationship between both measures of disordered eating and difficulties with emotion regulation. Findings support further research into the effectiveness of cognitive bias modification techniques with respect to disordered eating and the reduction of emotion regulation difficulties.
The work of Giorgio Agamben has been widely used by criminologists and others to explore policing and sovereignty across the globe. In this article, I explore Agamben’s conceptual framework, focusing ...on the commonly deployed ideas of ‘state of exception’ and ‘ homo sacer’. I highlight the limitations of Agamben’s legalistic theories, and argue that they leave us with an impoverished understanding of how sovereignty is negotiated in everyday life. As I demonstrate, scholars who have attempted to adapt Agamben’s ideas have failed to overcome these limitations in his analysis. I conclude that we must look for new ways forward and introduce the concept of ‘permissive space’ as an alternative to Agamben’s theoretical framework: an idea that allows a more nuanced and comprehensive analysis. Drawing on 10 months of fieldwork in Durban, South Africa, I illustrate the utility of this terminology for our analysis of policing.
Environmental health remains a niche topic in bioethics, despite being a prominent social determinant of health. In this paper we argue that if bioethicists are to take the project of health justice ...as a serious one, then we have to address environmental injustices and the threats they pose to our bioethics principles, health equity, and clinical care. To do this, we lay out three arguments supporting prioritizing environmental health in bioethics based on bioethics principles including a commitment to vulnerable populations and justice. We also highlight and advocate for environmental law efforts that align with these priorities, focusing specifically on the need for a right to a healthy environment. Our intention is to draw attention to the legal and ethical concepts that underlie the importance of a healthy environment, and urge bioethicists to prioritize both legal and ethical advocacy against environmental injustices in their practice.
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