This article gives information on an international ring trial of the epidermal-equivalent (EE) sensitizer potency assay.
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Hyperhomocysteinemia is a risk factor for cardiovascular disease, neurological disorders, and bone abnormalities. The key enzyme in homocysteine metabolism, cystathionine-β-synthase (CBS) is recognized as a target for new homocysteine-lowering therapies including enzyme replacement and gene therapy. Currently, there are no pharmacotherapies available that enhance CBS activity through its allosteric mechanism. The only known allosteric activator of CBS is S-adenosyl-L-methionine (SAM), which is available as a food supplement, but its effectiveness is limited by low membrane permeability and universal involvement in methylation reactions as a substrate. The discovery of CBS activators in high-throughput screening is challenging due to a lack of dedicated assays. Available HTS-compatible activity assays for CBS rely on measuring the product hydrogen sulfide or methanethiol where the signal increases with increased CBS activity. In the case of fluorescence-based assays, it is challenging to discern activators from autofluorescent compounds. In this study, we introduce a homocysteine consumption assay for isolated human CBS (HconCBS) based on the absorbance of Ellman's reagent. This assay leverages a decrease in signal upon CBS activation, with performance parameters exceeding the requirements for high-throughput screening. In a commercial library of 3010 compounds, the HconCBS assay identified 10 hit compounds as more active than SAM, whereas a fluorescence-based assay using 7-azido-4-methylcoumarin (AzMC) identified 141 hits. HconCBS identified 101 compounds with autoabsorbance which did not include hit compounds, while the fluorescence-based assay identified 383 autofluorescent compounds which included all hit compounds. While 4 out of 10 HconCBS hits were confirmed when purchased from a new source, the compounds affected homocysteine rather than CBS. Nevertheless, HconCBS consistently detected the CBS activator seleno-adenosyl-L-methionine (SeAM) added to 4 library plates and re-discovered the same library hits in 3 out of 4 re-screened plates. Taken together, HconCBS was designed to enable the discovery of allosteric CBS activators with greater reliability than fluorescence-based methods. Despite identifying some compounds that acted on homocysteine rather than CBS, the assay consistently identified the CBS activators SAM and SeAM and demonstrated reproducibility across two screening rounds. These findings establish HconCBS as a valuable tool for identifying potential therapeutic candidates for hyperhomocysteinemia, addressing a key gap in the development of CBS-targeted pharmacotherapies.
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To accelerate differentiation between Staphylococcus aureus and Coagulase Negative Staphylococci (CNS), this study aimed to compare six different DNA extraction methods from 2 commonly used blood culture materials, i.e. BACTEC and Bact/ALERT. Furthermore, we analyzed the effect of reduced blood culture times for detection of Staphylococci directly from blood culture material. A real-time PCR duplex assay was used to compare 6 different DNA isolation protocols on two different blood culture systems. Negative blood culture material was spiked with MRSA. Bacterial DNA was isolated with: automated extractor EasyMAG (3 protocols), automated extractor MagNA Pure LC (LC Microbiology Kit MGrade), a manual kit MolYsis Plus, and a combination between MolYsis Plus and the EasyMAG. The most optimal isolation method was used to evaluate reduced bacterial culture times. Bacterial DNA isolation with the MolYsis Plus kit in combination with the specific B protocol on the EasyMAG resulted in the most sensitive detection of S.aureus, with a detection limit of 10 CFU/ml, in Bact/ALERT material, whereas using BACTEC resulted in a detection limit of 100 CFU/ml. An initial S.aureus load of 1 CFU/ml blood can be detected after 5 hours of culture in Bact/ALERT3D by combining the sensitive isolation method and the tuf LightCycler assay.
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Development of novel testing strategies to detect adverse human health effects is of interest to replace in vivo-based drug and chemical safety testing. The aim of the present study was to investigate whether physiologically based kinetic (PBK) modeling-facilitated conversion of in vitro toxicity data is an adequate approach to predict in vivo cardiotoxicity in humans. To enable evaluation of predictions made, methadone was selected as the model compound, being a compound for which data on both kinetics and cardiotoxicity in humans are available. A PBK model for methadone in humans was developed and evaluated against available kinetic data presenting an adequate match. Use of the developed PBK model to convert concentration–response curves for the effect of methadone on human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) in the so-called multi electrode array (MEA) assay resulted in predictions for in vivo dose–response curves for methadone-induced cardiotoxicity that matched the available in vivo data. The results also revealed differences in protein plasma binding of methadone to be a potential factor underlying variation between individuals with respect to sensitivity towards the cardiotoxic effects of methadone. The present study provides a proof-of-principle of using PBK modeling-based reverse dosimetry of in vitro data for the prediction of cardiotoxicity in humans, providing a novel testing strategy in cardiac safety studies.
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Aims: The aim of this study is to evaluate the nurses' experiences with the Nursing Crisis Meetings and to identify nurses' needs regarding the future governance structure. Design: Qualitative study. Methods: Two focus groups were conducted in February 2022 with participants of the Nursing Crisis Meetings (N= 15). We used thematic analysis to describe themes. Results: We identified five themes: opportunity to speak up, call for nursing leadership, call for control over practice and autonomy, development of a governance infrastructure and development of the professional nurse role. Conclusion: Nurses experienced the Nursing Crisis Meetings to be a positive and empowering infrastructure, which facilitates the unique opportunity to speak up and share experiences and concerns. This new infrastructure is a promising strategy to engage nurses during a pandemic and to build on a professional governance structure. Impact: This paper highlights the need for nurses to speak up and be engaged during the COVID-19 pandemic and gives a practical example of how to put this infrastructure into practice.
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For almost fifteen years, the availability and regulatory acceptance of new approach methodologies (NAMs) to assess the absorption, distribution, metabolism and excretion (ADME/biokinetics) in chemical risk evaluations are a bottleneck. To enhance the field, a team of 24 experts from science, industry, and regulatory bodies, including new generation toxicologists, met at the Lorentz Centre in Leiden, The Netherlands. A range of possibilities for the use of NAMs for biokinetics in risk evaluations were formulated (for example to define species differences and human variation or to perform quantitative in vitro-in vivo extrapolations). To increase the regulatory use and acceptance of NAMs for biokinetics for these ADME considerations within risk evaluations, the development of test guidelines (protocols) and of overarching guidance documents is considered a critical step. To this end, a need for an expert group on biokinetics within the Organisation of Economic Cooperation and Development (OECD) to supervise this process was formulated. The workshop discussions revealed that method development is still required, particularly to adequately capture transporter mediated processes as well as to obtain cell models that reflect the physiology and kinetic characteristics of relevant organs. Developments in the fields of stem cells, organoids and organ-on-a-chip models provide promising tools to meet these research needs in the future.
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Background and aims: Observational data indicate that diets rich in fruits and vegetables have a positive effect on inflammatory status, improve metabolic resilience and may protect against the development of non-communicable diseases. Nevertheless, experimental evidence demonstrating a causal relationship between nutrient intake (especially whole foods) and changes in metabolic health is scarce. This study investigated the pleiotropic effects of sulforaphane from broccoli sprouts, compared to pea sprouts, on biomarkers of endothelial function, inflammation and metabolic stress in healthy participants subjected to a standardized caloric challenge.Methods: In this double-blind, crossover, randomized, placebo-controlled trial 12 healthy participants were administered 16 g broccoli sprouts, or pea sprouts (placebo) followed by the standardized high-caloric drink PhenFlex given to disturb healthy homeostasis. Levels of inflammatory biomarkers and metabolic parameters were measured in plasma before and 2 h after the caloric overload.Results: Administration of broccoli sprouts promoted an increase in levels of CCL-2 induced by caloric load (p = 0.017). Other biomarkers (sICAM-1, sVCAM-1, hs-CRP, and IL-10) individually showed insignificant tendencies toward increase with administration of sulforaphane. Combining all studied biomarkers into the systemic low-grade inflammation score further confirmed upregulation of the inflammatory activity (p = 0.087) after sulforaphane. No significant effects on biomarkers of metabolic stress were detected.Conclusion: This study has demonstrated that sulforaphane facilitated development of a mild pro-inflammatory state during the caloric challenge, which could be suggestive of the onset of the hormetic response induced by this phytonutrient. The use of integrative outcomes measures such as the systemic low-grade inflammation score can be viewed as a more robust approach to study the subtle and pleiotropic effects of phytonutrients.Clinical trial registration:www.clinicaltrials.gov, identifier NCT05146804.Keywords: biomarkers; diet; glucoraphanin; hormesis; inflammation; nutrients; phenotypic flexibility; sulforaphane.
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tIn this study we aimed to identify genes that are responsive to pertussis toxin (PTx) and might eventu-ally be used as biological markers in a testing strategy to detect residual PTx in vaccines. By microarrayanalysis we screened six human cell types (bronchial epithelial cell line BEAS-2B, fetal lung fibroblastcell line MRC-5, primary cardiac microvascular endothelial cells, primary pulmonary artery smooth mus-cle cells, hybrid cell line EA.Hy926 of umbilical vein endothelial cells and epithelial cell line A549 andimmature monocyte-derived dendritic cells) for differential gene expression induced by PTx. Imma-ture monocyte-derived dendritic cells (iMoDCs) were the only cells in which PTx induced significantdifferential expression of genes. Results were confirmed using different donors and further extendedby showing specificity for PTx in comparison to Escherichia coli lipopolysaccharide (LPS) and Bordetellapertussis lipo-oligosaccharide (LOS). Statistical analysis indicated 6 genes, namely IFNG, IL2, XCL1, CD69,CSF2 and CXCL10, as significantly upregulated by PTx which was also demonstrated at the protein levelfor genes encoding secreted proteins. IL-2 and IFN- gave the strongest response. The minimal PTx con-centrations that induced production of IL-2 and IFN- in iMoDCs were 12.5 and 25 IU/ml, respectively.High concentrations of LPS slightly induced IFN- but not IL-2, while LOS and detoxified pertussis toxindid not induce production of either cytokine. In conclusion, using microarray analysis we evaluated sixhuman cell lines/types for their responsiveness to PTx and found 6 PTx-responsive genes in iMoDCs ofwhich IL2 is the most promising candidate to be used as a biomarker for the detection of residual PTx.
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Background: Adverse outcome pathway (AOP) networks are versatile tools in toxicology and risk assessment that capture and visualize mechanisms driving toxicity originating from various data sources. They share a common structure consisting of a set of molecular initiating events and key events, connected by key event relationships, leading to the actual adverse outcome. AOP networks are to be considered living documents that should be frequently updated by feeding in new data. Such iterative optimization exercises are typically done manually, which not only is a time-consuming effort, but also bears the risk of overlooking critical data. The present study introduces a novel approach for AOP network optimization of a previously published AOP network on chemical-induced cholestasis using artificial intelligence to facilitate automated data collection followed by subsequent quantitative confidence assessment of molecular initiating events, key events, and key event relationships. Methods: Artificial intelligence-assisted data collection was performed by means of the free web platform Sysrev. Confidence levels of the tailored Bradford-Hill criteria were quantified for the purpose of weight-of-evidence assessment of the optimized AOP network. Scores were calculated for biological plausibility, empirical evidence, and essentiality, and were integrated into a total key event relationship confidence value. The optimized AOP network was visualized using Cytoscape with the node size representing the incidence of the key event and the edge size indicating the total confidence in the key event relationship. Results: This resulted in the identification of 38 and 135 unique key events and key event relationships, respectively. Transporter changes was the key event with the highest incidence, and formed the most confident key event relationship with the adverse outcome, cholestasis. Other important key events present in the AOP network include: nuclear receptor changes, intracellular bile acid accumulation, bile acid synthesis changes, oxidative stress, inflammation and apoptosis. Conclusions: This process led to the creation of an extensively informative AOP network focused on chemical-induced cholestasis. This optimized AOP network may serve as a mechanistic compass for the development of a battery of in vitro assays to reliably predict chemical-induced cholestatic injury.
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