Prevalence and persistence of microcystin in shoreline lake sediments and porewater, and associated potential for human health risk

Midlatitude waterbodies are experiencing increased cyanobacteria blooms that necessitate health advisories to protect waterbody users. Although surface waters may contain cyanotoxins such as microcystin (MC), at concentrations that pose potential public health risks, little is known about MC contamination of shoreline sediments. Based on growing evidence that lake and reservoir sediments can accumulate MCs, we hypothesized that shoreline sediments (i.e., recreational beaches) may accumulate MCs and thereby pose a potential health risk to recreational users even if people stay out of contaminated water. We sampled nearshore surface water, shoreline sediment, and porewater from seven Washington State, USA, lakes/reservoirs recreational beaches to determine MC presence/absence during or immediately following cyanobacteria blooms. We found MCs in shoreline sediments at all waterbodies using ELISA and LC-MS/MS. MC concentrations in shoreline sediments and porewaters persisted for 20 days following dissipation of cyanobacteria blooms when MC concentrations were near analytical reporting limits in corresponding surface waters. A human health risk assessment based on potential MC exposure through incidental ingestion of porewaters and sediments found, even when very high MC concentrations occur in surface waters (i.e., >11,000 μg/L), estimated ingestion doses are below MC World Health Organization tolerable daily intake and U.S. Environmental Protection Agency's risk reference dose. While our findings suggest MCs in Washington State recreational beaches in 2018 did not present a significant human health risk, future blooms with higher MC concentrations could pose human health risks via the shoreline sediment/porewater exposure pathway.

Using Human-Centred Design to Develop Innovative Approaches to Improve Delivery of Brief Interventions in Primary Care: The HealthEir Project

Introduction

A priority action of the Healthy Ireland implementation plan is the Making Every Contact Count initiative (MECC) that aims to leverage the 30 million annual contacts with the healthcare system by asking every health worker to deliver brief interventions [1]. Benefits of brief interventions are well established, but GPs and pharmacists report challenges implementing them in practice including limited training, time, and poor fit with existing practices [2].

Aim

This government-funded Sláintecare project aimed to develop a novel method for brief interventions in pharmacy/GP settings using human-centred design.

Methods

User research was carried out with twelve users, including patients (3), GPs (4), and pharmacists (5) to identify their needs and priorities. Participants were recruited via email using a purposive sampling approach and completed semi-structured interviews with a design researcher. All participants invited agreed to participate. Next, a series of design sprints were completed with the research team. Design sprints allowed the team to integrate insights from user research with findings from a literature review/secondary research to understand pain points, identify stakeholder and user goals, and develop a list of initial design specifications. This list was used to develop and iterate a series of prototype solutions. Prototype service blueprints and wireframes (simple, two-dimensional schematic illustrations of the digital interface) were developed and tested with users before final versions were agreed.

Results

Findings from the interviews and literature review indicated (1) the main barrier to adoption was time, (2) patients and pharmacists were very positive about brief interventions with GPs more hesitant, (3) an approach blending technology with a consultation was preferred, and (4) having a specific list of local supports was important. Prototyping and evaluation processes identified that a simple interface with a clear indication of progress were preferred.

A blended intervention combining a tablet-based digital tool and structured interaction was developed. The interface was designed to maximise use of patient and healthcare professional time, and mapped to the 5As approach (which is underpinned by principles of motivational interviewing, shared-decision making, and readiness to change frameworks). The HealthEir digital tool enables patients to self-complete the Ask, Advise, and Assess phases of a brief intervention using a tablet device while waiting to see their pharmacist/GP. The pharmacist or GP then review the patient’s responses, risk level, and importance confidence and readiness scores. They complete the Assist and Arrange elements during the consultation, supported by a directory of local/national patient support services before printing information tickets for the patient to keep. The HealthEir intervention has been successfully rolled out at eight pilot pharmacy sites nationally, with a mix of urban/rural sites, and independent/chain pharmacies.

Conclusions

Adopting an interdisciplinary approach based on human-centred design principles led to the development of a blended brief intervention that has been successfully introduced in pilot sites across Ireland. While the implementation has been smooth despite COVID-19 challenges, and initial feedback has been very positive, the impact cannot yet be fully evaluated as research is ongoing. Future work will involve extending the intervention to include other healthcare professionals.

References

1. Making Every Contact Count Framework https://www.hse.ie/eng/about/who/healthwellbeing/making-every-contact-count/framework/framework.html (accessed Oct 10, 2020)

2. Keyworth C, Epton T, Goldthorpe J, Calam R, Armitage CJ. ‘It's difficult, I think it's complicated’: Health care professionals’ barriers and enablers to providing opportunistic behaviour change interventions during routine medical consultations. British journal of health psychology. 2019 Sep;24(3):571–92.

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

Hydrogen embrittlement is a complex phenomenon, involving several length- and timescales, that affects a large class of metals. It can significantly reduce the ductility and load-bearing capacity and cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Despite a large research effort in attempting to understand the mechanisms of failure and in developing potential mitigating solutions, hydrogen embrittlement mechanisms are still not completely understood. There are controversial opinions in the literature regarding the underlying mechanisms and related experimental evidence supporting each of these theories. The aim of this paper is to provide a detailed review up to the current state of the art on the effect of hydrogen on the degradation of metals, with a particular focus on steels. Here, we describe the effect of hydrogen in steels from the atomistic to the continuum scale by reporting theoretical evidence supported by quantum calculation and modern experimental characterisation methods, macroscopic effects that influence the mechanical properties of steels and established damaging mechanisms for the embrittlement of steels. Furthermore, we give an insight into current approaches and new mitigation strategies used to design new steels resistant to hydrogen embrittlement.

Direct observation of individual hydrogen atoms at trapping sites in a ferritic steel

The design of atomic-scale microstructural traps to limit the diffusion of hydrogen is one key strategy in the development of hydrogen-embrittlement-resistant materials. In the case of bearing steels, an effective trapping mechanism may be the incorporation of finely dispersed V-Mo-Nb carbides in a ferrite matrix. First, we charged a ferritic steel with deuterium by means of electrolytic loading to achieve a high hydrogen concentration. We then immobilized it in the microstructure with a cryogenic transfer protocol before atom probe tomography (APT) analysis. Using APT, we show trapping of hydrogen within the core of these carbides with quantitative composition profiles. Furthermore, with this method the experiment can be feasibly replicated in any APT-equipped laboratory by using a simple cold chain.

Robust Translation of γ-Secretase Modulator Pharmacology across Preclinical Species and Human Subjects

The amyloid-β peptide (Aβ)—in particular, the 42–amino acid form, Aβ1-42—is thought to play a key role in the pathogenesis of Alzheimer’s disease (AD). Thus, several therapeutic modalities aiming to inhibit Aβ synthesis or increase the clearance of Aβ have entered clinical trials, including γ-secretase inhibitors, anti-Aβ antibodies, and amyloid-β precursor protein cleaving enzyme inhibitors. A unique class of small molecules, γ-secretase modulators (GSMs), selectively reduce Aβ1-42 production, and may also decrease Aβ1-40 while simultaneously increasing one or more shorter Aβ peptides, such as Aβ1-38 and Aβ1-37. GSMs are particularly attractive because they do not alter the total amount of Aβ peptides produced by γ-secretase activity; they spare the processing of other γ-secretase substrates, such as Notch; and they do not cause accumulation of the potentially toxic processing intermediate, β-C-terminal fragment. This report describes the translation of pharmacological activity across species for two novel GSMs, (S)-7-(4-fluorophenyl)-N2-(3-methoxy-4-(3-methyl-1H-1,2,4-triazol-1-yl)phenyl)-N4-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidine-2,4-diamine (BMS-932481) and (S,Z)-17-(4-chloro-2-fluorophenyl)-34-(3-methyl-1H-1,2,4-triazol-1-yl)-16,17-dihydro-15H-4-oxa-2,9-diaza-1(2,4)-cyclopenta[d]pyrimidina-3(1,3)-benzenacyclononaphan-6-ene (BMS-986133). These GSMs are highly potent in vitro, exhibit dose- and time-dependent activity in vivo, and have consistent levels of pharmacological effect across rats, dogs, monkeys, and human subjects. In rats, the two GSMs exhibit similar pharmacokinetics/pharmacodynamics between the brain and cerebrospinal fluid. In all species, GSM treatment decreased Aβ1-42 and Aβ1-40 levels while increasing Aβ1-38 and Aβ1-37 by a corresponding amount. Thus, the GSM mechanism and central activity translate across preclinical species and humans, thereby validating this therapeutic modality for potential utility in AD.

The γ-Secretase Modulator, BMS-932481, Modulates Aβ Peptides in the Plasma and Cerebrospinal Fluid of Healthy Volunteers

The pharmacokinetics, pharmacodynamics, safety, and tolerability of BMS-932481, a γ-secretase modulator (GSM), were tested in healthy young and elderly volunteers after single and multiple doses. BMS-932481 was orally absorbed, showed dose proportionality after a single dose administration, and had approximately 3-fold accumulation after multiple dosing. High-fat/caloric meals doubled the C_max and area under the curve and prolonged T_max by 1.5 hours. Consistent with the preclinical pharmacology of GSMs, BMS-932481 decreased cerebrospinal fluid (CSF) Aβ39, Aβ40, and Aβ42 while increasing Aβ37 and Aβ38, thereby providing evidence of γ-secretase enzyme modulation rather than inhibition. In plasma, reductions in Aβ40 and Aβ42 were observed with no change in total Aβ; in CSF, modest decreases in total Aβ were observed at higher dose levels. Increases in liver enzymes were observed at exposures associated with greater than 70% CSF Aβ42 lowering after multiple dosing. Although further development was halted due to an insufficient safety margin to test the hypothesis for efficacy of Aβ lowering in Alzheimer’s disease, this study demonstrates that γ-secretase modulation is achievable in healthy human volunteers and supports further efforts to discover well tolerated GSMs for testing in Alzheimer’s disease and other indications.

Biodegradation of the alkaline cellulose degradation products generated during radioactive waste disposal

The anoxic, alkaline hydrolysis of cellulosic materials generates a range of cellulose degradation products (CDP) including α and β forms of isosaccharinic acid (ISA) and is expected to occur in radioactive waste disposal sites receiving intermediate level radioactive wastes. The generation of ISA's is of particular relevance to the disposal of these wastes since they are able to form complexes with radioelements such as Pu enhancing their migration. This study demonstrates that microbial communities present in near-surface anoxic sediments are able to degrade CDP including both forms of ISA via iron reduction, sulphate reduction and methanogenesis, without any prior exposure to these substrates. No significant difference (n = 6, p = 0.118) in α and β ISA degradation rates were seen under either iron reducing, sulphate reducing or methanogenic conditions, giving an overall mean degradation rate of 4.7×10⁻² hr⁻¹ (SE±2.9×10⁻³). These results suggest that a radioactive waste disposal site is likely to be colonised by organisms able to degrade CDP and associated ISA's during the construction and operational phase of the facility.

Many-beam dynamical simulation of electron backscatter diffraction patterns

We present an approach for the simulation of complete electron backscatter diffraction (EBSD) patterns where the relative intensity distributions in the patterns are accurately reproduced. The Bloch wave theory is applied to describe the electron diffraction process. For the simulation of experimental patterns with a large field of view, a large number of reflecting planes has to be taken into account. This is made possible by the Bethe perturbation of weak reflections. Very good agreement is obtained for simulated and experimental patterns of gallium nitride GaN{0001} at 20kV electron energy. Experimental features like zone-axis fine structure and higher-order Laue zone rings are accurately reproduced. We discuss the influence of the diffraction of the incident beam in our experiment.

Characterization of nitride thin films by electron backscatter diffraction

Thin films incorporating GaN, InGaN and AlGaN are presently arousing considerable excitement because of their suitability for UV and visible light-emitting diodes and laser diodes. However, because of the lattice mismatch between presently used substrates and epitaxial nitride thin films, the films are of variable quality In this paper we describe our preliminary studies of nitride thin films using electron backscattered diffraction (EBSD). We show that the EBSD technique may be used to reveal the relative orientation of an epitaxial thin film with respect to its substrate (a 90 degrees rotation between a GaN epitaxial thin film and its sapphire substrate is observed) and to determine its tilt (a GaN thin film was found to be tiltedby 13 +/- 1 degrees towards [1010]GaN), where the tilt is due to the inclination of the sapphire substrate (cut off-axis by 10 degrees from (0001)sapphire towards (1010)sapphire). We compare EBSD patterns obtained from As-doped GaN films grown by plasma-assisted molecular beam epitaxy (PA-MBE) with low and high As4 flux, respectively. Higher As4 flux results in sharper, better defined patterns, this observation is consistent with the improved surface morphology observed in AFM studies. Finally, we show that more detail can be discerned in EBSD patterns from GaN thin films when samples are cooled.

Identification, partial sequence and genetic analysis of mlpA, a novel gene encoding a myosin-related protein in Physarum polycephalum

Studies of motility in Physarum polycephalum have concentrated on the well-defined actomyosin system in plasmodia. It is clear from recent genetic studies in lower eukaryotes that myosin is involved in a number of physiological processes in addition to the contractile functions previously ascribed to the classical type II myosins. Moreover, the myosin protein family has proved to be more complex than anticipated, with an increasing number of reported specialized isoforms. Although a myosin type II activity has been identified in both amoebae and plasmodia of P. polycephalum, and it has been inferred that these proteins undergo a phase-specific isoform switch during development, this phenomenon has not been analysed genetically. In an effort to understand the putative developmental expression of actomyosin-associated proteins, we isolated a 180-kDa protein from amoebae which is highly enriched, along with actin and myosin, in actomyosin preparations in the presence of mM concentrations of Mg++ ions and 10 mM of ATP. Using polyclonal antisera raised against pl80 we have cloned and sequenced a partial cDNA encoding a protein whose predicted amino-acid sequence indicates some similarity with the Dictyostelium discoideum myosin heavy-chain tail domain. Southern-blot and RFLP analyses indicate that the gene involved, designated mlpA (myosin-like protein), occurs in a single copy in the genome, is a novel Physarum gene and is expressed during amoebal and plasmodial growth and in the dormant forms of both these cell types.

Estimation of ambient chronic toxicity in a polluted creek system

Ambient water toxicity estimations were conducted in Piles Creek as part of an ecological risk assessment study. This creek is part of a highly polluted estuarine system located near Linden, New Jersey. An upstream and a downstream site in the creek were evaluated for effects on survival, growth and sexual maturity of the estuarine mysid, Mysidopsis bahia. Manasquan Inlet, Manasquan, New Jersey, served as the reference site. Seven-day screening toxicity tests were conducted once a month over a three month period. Results indicate that survival of mysids was not affected in any toxicity test. Mysid growth was significantly reduced at both of the test sites, in two out of three trials. Sexual maturity was shown to be adversely affected in mysids exposed to ambient waters from both test sites throughout the duration of the study.

Variable susceptibility to NK activity of cloned cell lines derived from a primary rat rhabdomyosarcoma: relationship to metastatic potential

In vitro cloned lines derived from a primary nickel-induced rat rhabdomyosarcoma exhibited diverse levels of susceptibility to spontaneous NK activity. The presence of NK target structures was revealed by competition assays on all cloned cell lines, and the NK susceptibility of the tumour lines varied according to their osmotic fragility. Tumour cell lines derived from metastatic lung nodules presented similar NK susceptibilities to cells originating from the primary tumour. However, cloned cell lines differed in their capacity to form lung colonies after i.v. injection, and in their potential for invading lungs after s.c. primary tumour development. No correlation was found between lung colonization potential and NK resistance. Studies of the correlation between metastatic potential and NK sensitivity revealed that (1) all the NK resistant tumour cells were highly metastatic; (2) NK susceptible tumour cells could be either highly or weakly metastatic. Therefore, highly metastatic tumour cells could be either resistant or susceptible to NK lysis. We conclude that the property of resistance to NK contributes to a high metastatic potential. However, other properties could counterbalance and finally prevail over NK susceptibility thus enabling NK susceptible cell lines to be also highly metastatic.

Alterations of spontaneous quantal transmitter release at the mammalian neuromuscular junction induced by divalent and trivalent ions

The present studies have demonstrated that Ca and Sr have a similar ability to support the release of spontaneous quanta of transmitter at the rat neuromuscular junction. The foreign ions Co, Pb, Zn and La have also been shown to support spontaneous release, although the time course of the increase in miniature end-plate potentials (m.e.p.p.s) caused by these ions is much slower than that caused by Ca and Sr. However, Sr, Co, Pb and Zn were unable to sustain m.e.p.p.s for prolonged periods. High extracellular K (10--15 mM) inhibited the steady state m.e.p.p. frequency in Ca and Sr concentrations above 1 mM, and also delayed the m.e.p.p. frequency increase induced by 1 mM Pb. It is suggested that K ions directly inhibit divalent ion entry into the nerve terminal.