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Current Protocols in Toxicology

Pranav Joshi, Soo-Yeon Kang, Akshata Datar, Moo-Yeal Lee
High-content imaging (HCI) assays on two-dimensional (2D) cell cultures often do not represent in vivo characteristics accurately, thus reducing the predictability of drug toxicity/efficacy in vivo. On the other hand, conventional 3D cell cultures are relatively low throughput and possess difficulty in cell imaging. To address these limitations, a miniaturized 3D cell culture has been developed on a micropillar/microwell chip platform with human cells encapsulated in biomimetic hydrogels. Model compounds are used to validate human cell microarrays for high-throughput assessment of mechanistic toxicity...
November 2, 2018: Current Protocols in Toxicology
Josi Herron, Kelly M Hines, Libin Xu
Cholesterol and cholesterol-derived oxysterols are critical for embryonic development, synapse formation and function, and myelination, among other biological functions. Indeed, alterations in levels of cholesterol, sterol precursors, and oxysterols result in a variety of developmental disorders, emphasizing the importance of cholesterol homeostasis. The ability of xenobiotics to reproduce similar phenotypes by altering cholesterol homeostasis has increasingly become of interest. Therefore, the ability to quantitatively assess alterations in cholesterol homeostasis resulting from exposure to xenobiotics is of value...
November 2018: Current Protocols in Toxicology
Maria A Velez-Quinones, Hanna Xu, Nhu Vo, Joanna M Gaitens, Melissa A McDiarmid, Michael R Lewin-Smith, Frederick G Strathmann
We have developed and validated a method for the simultaneous quantitative measurement of total uranium (TU) and uranium 235 U/238 U isotopic ratio (UIR) in urine by inductively coupled plasma mass spectrometry (ICP-MS) using a Thermo Scientific iCAP-Q instrument. The performance characteristics of the assay were determined to be in compliance with clinical laboratory standards. The assay was linear in the concentration range of 1.0 to 500.0 ng/liter TU. The method was precise and accurate with limits of detection of 2...
November 2018: Current Protocols in Toxicology
Maria A Velez-Quinones, Hanna Xu, Nhu Vo, Joanna M Gaitens, Melissa A McDiarmid, Michael R Lewin-Smith, Frederick G Strathmann
We developed and validated a method for the assessment of thirteen separate trace and toxic elements using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Included elements were as follows: aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, molybdenum, cadmium, tungsten, and lead. The measurements of all elements in urine samples were conducted using ICAP-Q ICP-MS in a single method. The performance characteristics of the assay were determined according to clinical laboratory standards...
November 2018: Current Protocols in Toxicology
Robert G Nichols, Jingwei Cai, Iain A Murray, Imhoi Koo, Philip B Smith, Gary H Perdew, Andrew D Patterson
Characterizing the reciprocal interactions between toxicants, the gut microbiota, and the host, holds great promise for improving our mechanistic understanding of toxic endpoints. Advances in culture-independent sequencing analysis (e.g., 16S rRNA gene amplicon sequencing) combined with quantitative metabolite profiling (i.e., metabolomics) have provided new ways of studying the gut microbiome and have begun to illuminate how toxicants influence the structure and function of the gut microbiome. Developing a standardized protocol is important for establishing robust, reproducible, and importantly, comparative data...
November 2018: Current Protocols in Toxicology
Taru Hilander, Svetlana Konovalova, Mügen Terzioglu, Henna Tyynismaa
Mitochondria are multifunctional organelles with their own genome and protein synthesis machinery. The 13 proteins encoded by mitochondrial DNA (mtDNA) are core subunits of the oxidative phosphorylation (OXPHOS) system producing the majority of cellular ATP. Yet most mitochondrial proteins are encoded by nuclear genes, synthesized by cytosolic ribosomes, and imported into mitochondria. Therefore, disturbances in cytosolic proteostasis have consequences on the gene expression and synthesis of mtDNA-encoded proteins and overall on mitochondrial function...
July 31, 2018: Current Protocols in Toxicology
Jacquelynn Benjamino, Lidia Beka, Joerg Graf
Microbiomes can be thought of as the integration of biotic and abiotic factors, including the microbial communities and the distinct physio-chemical properties that are present in a habitat. The microbes within a microbiome can influence the chemical environment by degrading medications inside patients or contaminants in the environment, such as hydrocarbons released after the Deepwater Horizon oil spill. Identifying and monitoring the relative abundance of microbes can help to elucidate variations in their response to toxins and should be considered as a variable in statistical analyses...
July 25, 2018: Current Protocols in Toxicology
Michael A Pellizzon, Matthew R Ricci
Poor diet reporting and improperly controlling laboratory animal diet continues to reduce our ability to interpret data effectively in animal studies. In order to make the best use of our resources and improve research transparency, proper reporting methods that include a diet design are essential to improving our understanding of the links between gut health and metabolic disease onset. This unit will focus on the importance of diet choice in laboratory animal studies, specifically as it relates to gut health, microbiome, and metabolic disease development...
July 20, 2018: Current Protocols in Toxicology
Christa Kietz, Vilma Pollari, Annika Meinander
As several diseases have been linked to dysbiosis of the human intestinal microflora, manipulation of the microbiota has emerged as an exciting new strategy for potentially treating and preventing diseases. However, the human microbiota consists of a plethora of different species, and distinguishing the impact of a specific bacterial species on human health is challenging. In tackling this challenge, the fruit fly Drosophila melanogaster, with its far simpler microbial composition, has emerged as a powerful model for unraveling host-microbe interactions...
June 22, 2018: Current Protocols in Toxicology
Laurie H Sanders, Jeremy P Rouanet, Evan H Howlett, Tess C Leuthner, John P Rooney, J Timothy Greenamyre, Joel N Meyer
Given the crucial role of DNA damage in human health and disease, it is important to be able to accurately measure both mitochondrial and nuclear DNA damage. This article describes a method based on a long-amplicon quantitative PCR-based assay that does not require a separate mitochondrial isolation step, which can often be labor-intensive and generate artifacts. The detailed basic protocol presented here is newly revised, with particular attention to application in Homo sapiens, Rattus norvegicus, and Caenorhabditis elegans resulting from changes in availability of PCR reagents...
May 2018: Current Protocols in Toxicology
Zaher A Radi, Zachary S Stewart, Shawn P O'Neil
Cellular development and homeostasis are regulated via programmed cell death (PCD; apoptosis), which is a genetically regulated cellular process. Accidental cell death (ACD; necrosis) can be triggered by chemical, physical, or mechanical stress. Necrosis is the presence of dead tissues or cells in a living organism regardless of the initiating process and can be observed in infectious and non-infectious diseases and toxicities. This article describes tissue-based immunohistotechnical protocols used for assessing PCD and necrosis in formalin-fixed tissues obtained from preclinical species used in investigative and toxicologic pathology...
May 2018: Current Protocols in Toxicology
Norimasa Tamehiro, Reiko Adachi, Yoshie Kimura, Shinobu Sakai, Reiko Teshima, Kazunari Kondo
A food allergy is a chronic inflammatory disease against dietary antigens with high prevalence in industrialized countries. Because there is currently no cure for food allergies, avoiding the allergen is crucial for the prevention of an allergic reaction. Therefore, a further understanding of the pathogenesis and risk factors that augment the sensitization to food allergens is required. We have previously developed a food allergy mouse model using transdermal sensitization, which influences the susceptibility to food allergies...
May 2018: Current Protocols in Toxicology
Shannon G Loelius, Sherry L Spinelli, Katie L Lannan, Richard P Phipps
In this document, we describe methods for the isolation, treatment, and functional testing of human blood platelets in vitro. Functional assays for inflammatory function include flow cytometry and immunoassays for platelet release of platelet factor 4, soluble CD40L, prostaglandin E2 , and thromboxane. Assays for platelet hemostatic function described here examine platelet spreading, aggregation using platelet-rich plasma, and thromboelastography. Also described here are methods for testing cigarette smoke on primary human platelets in vitro, which our lab developed to address a major knowledge gap regarding how cigarette smoke dysregulates platelets and how this platelet dysregulation contributes to cardiovascular disease...
May 2018: Current Protocols in Toxicology
Prathap Kumar Mahalingaiah, Tammy Palenski, Terry R Van Vleet
Hematotoxicity is a significant issue for drug safety and can result from direct cytotoxicity toward circulating mature blood cell types as well as targeting of immature blood-forming stem cells/progenitor cells in the bone marrow. In vitro models for understanding and investigating the hematotoxicity potential of new test items/drugs are critical in early preclinical drug development. The traditional method, colony forming unit (CFU) assay, is commonly used and has been validated as a method for hematotoxicity screening...
May 2018: Current Protocols in Toxicology
Andrew Smith, Justin Dowis, Deborah French
Voriconazole, isavuconazole, and posaconazole are triazole anti-fungal drugs commonly used to treat invasive fungal infections. Therapeutic drug monitoring is commonly carried out when patients are prescribed these drugs to ensure that the serum concentrations are sufficiently high for efficacy, but do not reach toxic concentrations. Mass spectrometric (MS) assays have been successfully utilized to determine the serum concentrations of these drugs. This protocol describes a sample preparation procedure and a liquid chromatography-tandem mass spectrometry assay for quantifying serum voriconazole, isavuconazole, and posaconazole in a single method...
May 2018: Current Protocols in Toxicology
Anthony Flamier, Supriya Singh, Theodore P Rasmussen
Human birth defects are relatively common and can be caused by exposure to environmental teratogens or to pharmaceuticals with teratogenic activities. Human embryonic stem cells (hESCs), by virtue of their pluripotent nature, provide an excellent cellular platform for teratogen detection and risk assessment. This unit describes detailed protocols for the preparation and validation of highly pluripotent hESCs, the production of large quantities of aggregated multicellular spheroids composed of hESCs, and these spheroids' differentiation into embryoid bodies (EBs)...
February 21, 2018: Current Protocols in Toxicology
Uttam Garg, Ada Munar, Clinton Frazee
Mycophenolic acid (MPA) is an immunosuppressant that is used in renal, liver, and heart transplantation. Due to its narrow therapeutic range, monitoring of MPA levels is essential to avoid toxicity and organ rejection. Although immunoassays are available for the determination of MPA, due to their higher specificity, mass spectrometry methods are preferred. In this unit, we describe a liquid chromatography tandem mass spectrometry (LC/MS/MS) method utilizing positive ionization electrospray and multiple reaction monitoring (MRM) for the quantification of levels of MPA and its conjugate MPA glucuronide (MPAG)...
February 21, 2018: Current Protocols in Toxicology
Asha Lekshmi, Shankara Narayanan Varadarajan, Santhik Subhasingh Lupitha, Mydhily Nair, Aneesh Chandrasekharan, T R Santhoshkumar
Recent cell biology studies reveal that a cell can die through multiple pathways via distinct signaling mechanisms. Among these, apoptosis and necrosis are two distinct cell death pathways, and their detection and discrimination is vital in the drug discovery process and in understanding diverse biological processes. Although sensitive assays for apoptosis and necrosis are available, it is extremely difficult to adapt any of these methods to discriminate apoptosis-inducing stimuli from necrosis-inducing stimuli because of the acquisition of secondary necrosis by apoptotic cells when they are not phagocytosed...
February 21, 2018: Current Protocols in Toxicology
Barbara L F Kaplan
Cannabinoid compounds refer to a group of more than 60 plant-derived compounds in Cannabis sativa, more commonly known as marijuana. Exposure to marijuana and cannabinoid compounds has been increasing due to increased societal acceptance for both recreational and possible medical use. Cannabinoid compounds suppress immune function, and while this could compromise one's ability to fight infections, immune suppression is the desired effect for therapies for autoimmune diseases. It is critical, therefore, to understand the effects and mechanisms by which cannabinoid compounds alter immune function, especially immune responses induced in autoimmune disease...
February 21, 2018: Current Protocols in Toxicology
Valentina Galbiati, Sue Gibbs, Erwin Roggen, Emanuela Corsini
Recently, an in vitro procedure, which combines the epidermal equivalent potency assay with assessment of IL-18 to provide a single test for identification and classification of skin sensitizers, was developed and validated. This unit will describe a simple in vitro method for estimation of the expected sensitization induction level interpolating in vitro EC50 and IL-18 SI2 values to predict LLNA EC3 and/or human NOEL from standards curves generated using reference contact allergens, based on the use of Reconstituted human Epidermis (RhE)...
February 21, 2018: Current Protocols in Toxicology
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