Characteristics of Sports-Related Injuries Presenting to a Pediatric Emergency Department.

OBJECTIVE: Pediatric injuries associated with participation in sports are common. Understanding the epidemiology and trends of sports-related injuries is an important component of injury prevention efforts and is the objective of this study. METHODS: A retrospective review of sports injuries presenting during the course of 1 year (2019) to the emergency department (ED) of Benjamin Russell Hospital for Children, a large academic children's hospital, was performed. Inclusion criteria focused on patients 18 years old and younger whose ED visit resulted from active participation in a sport. Cases were identified using International Classification of Diseases, Tenth Revision codes. Demographic data were collected and included sex, age, race, injury specifics (sport, location, type, and mechanism). Descriptive statistics were performed and categorical variables were analyzed using the χ2 test. RESULTS: A total of 1333 injuries seen by the ED during 2019 were sports injuries. Most commonly, these injuries were associated with football (43%), basketball (36%), soccer (11%), or baseball (8%). Considering sports-related injuries, 428 (32%) patients were 12 years and younger and 905 (68%) were 12 years old and older. The median age was 13 years (interquartile range 4 years). Other demographic findings included male sex 1143/1333 (86%) and Black race 835/1333 (63%). School was the most common location for sports injuries (28%). When comparing injuries by age groups (younger than 12 vs 12 and older), football and baseball injuries were more common in those younger than 12 years (53% vs 38%, z = 5.2, P < 0.00001; and 14.0% vs. 5.6%, z = 4.9, P < 0.00001, respectively), whereas basketball and soccer injuries were more common in those 12 years and older (43% vs 22%, z = 7.4, P < 0.00001; and 11.4% vs 9.3%, z = 5.9, P < 0.00001, respectively). When comparing injuries by sex, football and baseball injuries were more common in males (49% vs 6%, z = 11.1, P < 0.00001; and 9.4% vs. 2.1%, z = 3.3, P < 0.00001, respectively), whereas basketball and soccer injuries were more common in females (59% vs 32%, z = 7.2, P < 0.00001; and 27% vs 8%, z = 7.8, P < 0.00001, respectively. CONCLUSIONS: Sports injuries that are commonly encountered in the ED differ in age and sex. Basketball and soccer injuries were more likely to be encountered in older females, whereas baseball and football injuries were more likely seen in younger males. This may reflect efforts that have been previously focused on the sports considered to be higher risk, especially for concussive injuries. This information can help guide future preventive efforts provided by primary physicians, schools, and coaches.

A biologically based computational model for the hypothalamic-pituitary-thyroid (HPT) axis in Xenopus laevis larvae.

A biologically based computational model was developed to describe the hypothalamic-pituitary-thyroid (HPT) axis in developing Xenopus laevis larvae. The goal of this effort was to develop a tool that can be used to better understand mechanisms of thyroid hormone-mediated metamorphosis in X. laevis and predict organismal outcomes when those mechanisms are perturbed by chemical toxicants. In this report, we describe efforts to simulate the normal biology of control organisms. The structure of the model borrows from established models of HPT axis function in mammals. Additional features specific to X. laevis account for the effects of organism growth, growth of the thyroid gland, and developmental changes in regulation of thyroid stimulating hormone (TSH) by circulating thyroid hormones (THs). Calibration was achieved by simulating observed changes in stored and circulating levels of THs during a critical developmental window (Nieuwkoop and Faber stages 54-57) that encompasses widely used in vivo chemical testing protocols. The resulting model predicts that multiple homeostatic processes, operating in concert, can act to preserve circulating levels of THs despite profound impairments in TH synthesis. Represented in the model are several biochemical processes for which there are high-throughput in vitro chemical screening assays. By linking the HPT axis model to a toxicokinetic model of chemical uptake and distribution, it may be possible to use this in vitro effects information to predict chemical effects in X. laevis larvae resulting from defined chemical exposures.

In Vitro-In Vivo Extrapolation of Hepatic Biotransformation Data for Fish. III. An In-depth Case Study with Pyrene.

Computational models that predict chemical bioaccumulation in fish generally account for biotransformation using an apparent first-order whole-body rate constant (kB ; d-1 ). The use of such models requires, therefore, that methods exist for estimating kB , ideally without the need to expose live animals. One promising approach for estimating kB involves the extrapolation of measured in vitro intrinsic clearance (CLIN VITRO,INT ) to the whole animal (in vitro-in vivo extrapolation, [IVIVE]). To date, however, the accuracy of such predictions has been difficult to assess due to uncertainties associated with one or more extrapolation factors and/or a mismatch between fish used to generate in vitro data and those used to conduct in vivo exposures. In the present study we employed a combined in vitro and in vivo experimental approach to evaluate the IVIVE procedure using pyrene (PYR) as a model chemical. To the extent possible, measured rates of CLIN VITRO,INT were extrapolated to estimates of kB using extrapolation factors based on measured values. In vitro material (liver S9 fraction) was obtained from fish exposed to PYR in a controlled bioconcentration study protocol. Fish from the same study were then used to estimate in vivo kB values from an analysis of chemical depuration data. Averaged across four study groups, kB values estimated by IVIVE underestimated those determined from in vivo data by 2.6-fold. This difference corresponds to a 4.1-fold underestimation of true in vivo intrinsic clearance, assuming the liver is the only site of biotransformation. These findings are consistent with previous work performed using mammals and have important implications for use of measured CLIN VITRO,INT values in bioaccumulation assessments with fish. Environ Toxicol Chem 2023;42:1501-1515. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

An amended in vitro-in vivo extrapolation model that accounts for first pass clearance effects on chemical bioaccumulation in fish.

Measured rates of in vitro intrinsic clearance for fish may be extrapolated to the whole animal as a means of estimating a whole-body biotransformation rate constant (kB; d-1). This estimate of kB can then be used as an input to existing bioaccumulation prediction models. Most in vitro-in vivo extrapolation/bioaccumulation (IVIVE/B) modeling efforts to date have focused on predicting the chemical bioconcentration in fish (aqueous only exposure), with less attention paid to dietary exposures. Following dietary uptake, biotransformation in the gut lumen, intestinal epithelia, and liver can reduce chemical accumulation; however, current IVIVE/B models do not consider these first pass clearance effects on dietary uptake. Here we present an amended IVIVE/B model that accounts for first pass clearance. The model is then used to examine how biotransformation in the liver and intestinal epithelia (alone or combined) may impact chemical accumulation that occurs during dietary exposure. First pass clearance by the liver can greatly reduce dietary uptake of contaminants, but these effects are only apparent at rapid rates of in vitro biotransformation (first order depletion rate constant kDEP ≥ 10 h-1). The impact of first pass clearance becomes more pronounced when biotransformation in the intestinal epithelia is included in the model. Modelled results suggest that biotransformation in the liver and intestinal epithelia cannot entirely explain reduced dietary uptake reported in several in vivo bioaccumulation tests. This unexplained reduction in dietary uptake is attributed to chemical degradation in the gut lumen. These findings underscore the need for research to directly investigate luminal biotransformation in fish.

Models Used to Predict Chemical Bioaccumulation in Fish from in Vitro Biotransformation Rates Require Accurate Estimates of Blood-Water Partitioning and Chemical Volume of Distribution.

Methods for extrapolating measured in vitro intrinsic clearance to a whole-body biotransformation rate constant (kB ) have been developed to support modeled bioaccumulation assessments for fish. The inclusion of extrapolated kB values into existing bioaccumulation models improves the prediction of chemical bioconcentration factors (BCFs), but there remains a tendency for these methods to overestimate BCFs relative to measured values. Therefore, a need exists to evaluate the extrapolation procedure to assess potential sources of error in predicted kB values. We examined how three different approaches (empirically based, composition based, and polyparameter linear free energy relationships [ppLFERs]) used to predict chemical partitioning in vitro (liver S9 system; KS9W ), in blood (KBW ), and in whole fish tissues (KFW ) impact the prediction of a chemical's hepatic clearance binding term (fU ) and apparent volume of distribution (VD ), both of which factor into the calculation of kB and the BCF. Each approach yielded different KS9W , KBW , and KFW values, but resulted in fU values that were of similar magnitude and remained relatively constant at log octanol-water partition ratios (KOW ) greater than 4. This is because KBW and KS9W values predicted by any given approach exhibit a similar dependence on log KOW (i.e., regression slope), which results in a cancelation of "errors" when fU is calculated. In contrast, differences in KBW values predicted by the three approaches translate to differences in VD , and by extension kB and the BCF, which become most apparent at log KOW greater than 6. There is a need to collect KBW and VD data for hydrophobic chemicals in fish that can be used to evaluate and improve existing partitioning prediction approaches in extrapolation models for fish. Environ Toxicol Chem 2023;42:33-45. © 2022 SETAC.

Pediatric injury due to wheeled recreational devices: a single-institution retrospective study.

BACKGROUND: Injuries are the number one cause of death in children and cause significant morbidity. Common scenarios for injury include wheeled recreational devices (WRDs) that allow children to be mobile and independent (example ATV-all terrain vehicles, dirt bikes, bicycles, skateboards, and scooters). We present a case series review of these external causes of injury. This study aims to evaluate epidemiologic trends in WRD injuries and patterns in usage of protective gear. RESULTS: A total of 263 patients were identified as meeting criteria for inclusion with the following causes of injuries-103 bicycle, 73 ATV, 27 dirt bike, 14 skateboard, 13 motorcycle, 7 go carts, 3 hover board, 3 roller skates, 1 dune buggy, 1 motor scooter, 1 rip stick, and 1 tractor toy. Ages of patients ranged from 2 to 18 years of age with the greatest range being noted for bicycles (2-17 years) and motorcycles (3-18 years). The mean age was higher for motorcycle and skateboard (12.9 and 11.6, respectively) and lowest for scooter and bicycle (8.3 and 9.2, respectively). The majority of [overall study (97%) and for each mode of transportation] patients were Caucasian, which is in contrast to our overall ED population, which is only 42% Caucasian. The majority of patients were male [190 (72%)]. Over half of the overall patients, 159 of the 263 (60%), were not wearing a helmet (with only 10 charts having no documentation of helmet use). In regard to ATV riders specifically, 58% were not wearing helmets at the time of injury, with an additional 5 patients who reported their helmet came off. The lowest percentage of riders reporting appropriate helmet use was skateboarders with only 21% wearing helmets, and the highest percentage was dirt bike riders with 74% reporting helmet use. CONCLUSION: Common scenarios for injury include WRDs that allow children to be mobile and independent. Most of these injuries were found in Caucasian males between the ages of 9-12 with low rates of helmet use. This study adds to the literature with a description of the breadth of products children use and are injured while using.

Predicting the Accumulation of Ionizable Pharmaceuticals and Personal Care Products in Aquatic and Terrestrial Organisms.

The extent to which chemicals bioaccumulate in aquatic and terrestrial organisms represents a fundamental consideration for chemicals management efforts intended to protect public health and the environment from pollution and waste. Many chemicals, including most pharmaceuticals and personal care products (PPCPs), are ionizable across environmentally relevant pH gradients, which can affect their fate in aquatic and terrestrial systems. Existing mathematical models describe the accumulation of neutral organic chemicals and weak acids and bases in both fish and plants. Further model development is hampered, however, by a lack of mechanistic insights for PPCPs that are predominantly or permanently ionized. Targeted experiments across environmentally realistic conditions are needed to address the following questions: (1) What are the partitioning and sorption behaviors of strongly ionizing chemicals among species? (2) How does membrane permeability of ions influence bioaccumulation of PPCPs? (3) To what extent are salts and associated complexes with PPCPs influencing bioaccumulation? (4) How do biotransformation and other elimination processes vary within and among species? (5) Are bioaccumulation modeling efforts currently focused on chemicals and species with key data gaps and risk profiles? Answering these questions promises to address key sources of uncertainty for bioaccumulation modeling of ionizable PPCPs and related contaminants. Environ Toxicol Chem 2022;00:1-11. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Synthesis of "Naked" TeO2 Nanoparticles for Biomedical Applications.

Chalcogenide nanoparticles have become a very active field of research for their optoelectronic and biological properties. This article shows the production of tellurium dioxide nanoparticles (TeO2 NPs) by pulsed laser ablation in liquids. The produced nanoparticles were spherical with a diameter of around 70 nm. The energy band gap of those nanoparticles was determined to be around 5.2 eV. Moreover, TeO2 NPs displayed a dose-dependent antibacterial effect against antibiotic-resistant bacteria such as multidrug-resistant Escherichia coli (MDR E. coli) and methicillin-resistant Staphylococcus aureus (MR S. aureus). The "naked" nature of the nanoparticle surface helped to eradicate the antibiotic-resistant bacteria at a very low concentration, with IC50 values of ∼4.3 ± 0.9 and 3.7 ± 0.2 ppm for MDR E. coli and MR S. aureus, respectively, after just 8 h of culture. Further, the IC50 values of the naked TeO2 NPs against melanoma (skin cancer) and healthy fibroblasts were 1.6 ± 0.7 and 5.5 ± 0.2 ppm, respectively, for up to 72 h. Finally, to understand these optimal antibacterial and anticancer properties of the TeO2 NPs, the reactive oxygen species generated by the nanoparticles were measured. In summary, the present in vitro results demonstrate much promise for the presently prepared TeO2 NPs and they should be studied for a wide range of safe antibacterial and anticancer applications.

RespiCo: A novel, flexible, and stand-alone electronic respiratory coaching device.

Conscious respiratory pattern and rate control is desired by patients with some forms of pulmonary disease that are undergoing respiratory muscle conditioning and rehabilitation, by practitioners of meditation hoping to improve mindfulness and wellbeing, by athletes striving to obtain breathing control in order to increase competitiveness, and by engineers and scientists that wish to use the data from breathing subjects to test hypotheses and develop physiological monitoring systems. Although prerecorded audio sources and computer applications are available that guide breathing exercises, they often suffer from being inflexible and allow only limited customization of the breathing cues. Here we describe a small, lightweight, battery-powered, microprocessor-based respiratory coaching device (RespiCo), which through wireless or wired connections, can be easily customized to precisely guide subjects to breathe at desired respiratory rates using specific breathing patterns through visual, auditory, or haptic cues. Digital signals can also be captured from the device to document the breathing cues provided by the device for research purposes. It is anticipated that this device will have important utility for those who wish to be guided to breathe in a precise manner or in research and development of physiologic monitoring systems.

The Eco-Exposome Concept: Supporting an Integrated Assessment of Mixtures of Environmental Chemicals.

Organisms are exposed to ever-changing complex mixtures of chemicals over the course of their lifetime. The need to more comprehensively describe this exposure and relate it to adverse health effects has led to formulation of the exposome concept in human toxicology. Whether this concept has utility in the context of environmental hazard and risk assessment has not been discussed in detail. In this Critical Perspective, we propose-by analogy to the human exposome-to define the eco-exposome as the totality of the internal exposure (anthropogenic and natural chemicals, their biotransformation products or adducts, and endogenous signaling molecules that may be sensitive to an anthropogenic chemical exposure) over the lifetime of an ecologically relevant organism. We describe how targeted and nontargeted chemical analyses and bioassays can be employed to characterize this exposure and discuss how the adverse outcome pathway concept could be used to link this exposure to adverse effects. Available methods, their limitations, and/or requirement for improvements for practical application of the eco-exposome concept are discussed. Even though analysis of the eco-exposome can be resource-intensive and challenging, new approaches and technologies make this assessment increasingly feasible. Furthermore, an improved understanding of mechanistic relationships between external chemical exposure(s), internal chemical exposure(s), and biological effects could result in the development of proxies, that is, relatively simple chemical and biological measurements that could be used to complement internal exposure assessment or infer the internal exposure when it is difficult to measure. Environ Toxicol Chem 2022;41:30-45. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Ambulatory monitoring promises equitable personalized healthcare delivery in underrepresented patients.

The pandemic has brought to everybody's attention the apparent need of remote monitoring, highlighting hitherto unseen challenges in healthcare. Today, mobile monitoring and real-time data collection, processing and decision-making, can drastically improve the cardiorespiratory-haemodynamic health diagnosis and care, not only in the rural communities, but urban ones with limited healthcare access as well. Disparities in socioeconomic status and geographic variances resulting in regional inequity in access to healthcare delivery, and significant differences in mortality rates between rural and urban communities have been a growing concern. Evolution of wireless devices and smartphones has initiated a new era in medicine. Mobile health technologies have a promising role in equitable delivery of personalized medicine and are becoming essential components in the delivery of healthcare to patients with limited access to in-hospital services. Yet, the utility of portable health monitoring devices has been suboptimal due to the lack of user-friendly and computationally efficient physiological data collection and analysis platforms. We present a comprehensive review of the current cardiac, pulmonary, and haemodynamic telemonitoring technologies. We also propose a novel low-cost smartphone-based system capable of providing complete cardiorespiratory assessment using a single platform for arrhythmia prediction along with detection of underlying ischaemia and sleep apnoea; we believe this system holds significant potential in aiding the diagnosis and treatment of cardiorespiratory diseases, particularly in underserved populations.

Correction to Designing QSARs for Parameters of High Throughput Toxicokinetic Models Using Open-Source Descriptors.

The intrinsic metabolic clearance rate (Clint) and fraction of chemical unbound in plasma (fup) serve as important parameters for high throughput toxicokinetic models, but experimental data are limited for many chemicals. Open-source quantitative structure-activity relationship (QSAR) models for both parameters were developed to offer reliable in silico predictions for a diverse set of chemicals regulated under U.S. law, including pharmaceuticals, pesticides, and industrial chemicals. As a case study to demonstrate their utility, model predictions served as inputs to the TK component of a risk-based prioritization approach based on Bioactivity: Exposure Ratios (BER), in which a BER < 1 indicates exposures are predicted to exceed a biological activity threshold. When applied to a subset of the Tox21 screening library (6631 chemicals) we found that the proportion of chemicals with BER < 1 was similar using either in silico (1337/6631; 20.16%) or in vitro (151/850; 17.76%) parameters. Further, when considering only the chemicals in the Tox21 set with in vitro data, there was a high concordance of chemicals classified with either BER < 1 or >1 using either in silico or in vitro parameters (776/850, 91.30%). Thus, the presented QSARs may be suitable for prioritizing the risk posed by many chemicals for which measured in vitro TK data are lacking.

Implementation and effectiveness of the National Incident Management System's Incident Command System in law enforcement since 2003.

This paper investigates the use of the National Incident Management System (NIMS)'s Incident Command System (ICS) in law enforcement since Homeland Security Presidential Directive 5 was issued in 2003. It attempts to answer the following questions: (a) To what degree has law enforcement adopted the NIMS style ICS?; (b) To what degree has the NIMS/ICS framework been applicable to law enforcement?; and (c) Is the NIMS style ICS effective in the law enforcement response environment? The research includes a review of relevant case studies and literature and also includes the analysis of a survey instrument sent to 1,220 current and former law enforcement practitioners across the United States. The survey includes both open- and closed-ended questions. The data from closed-ended questions were compiled and displayed. Data from open-ended questions were grouped thematically. Responses were then assessed and compared with information gleaned from the literature review. Results indicate the system has been widely adopted by law enforcement, and its use is applicable and effective in some law enforcement responses. Its use in the highly chaotic initial phase of incidents, however, remains an open question.

Biotransformation Potential of Cationic Surfactants in Fish Assessed with Rainbow Trout Liver S9 Fractions.

Biotransformation may substantially reduce the extent to which organic environmental contaminants accumulate in fish. Presently, however, relatively little is known regarding the biotransformation of ionized chemicals, including cationic surfactants, in aquatic organisms. To address this deficiency, a rainbow trout liver S9 substrate depletion assay (RT-S9) was used to measure in vitro intrinsic clearance rates (CLint ; ml min-1 g liver-1 ) for 22 cationic surfactants that differ with respect to alkyl chain length and degree of methylation on the charged nitrogen atom. None of the quaternary N,N,N-trimethylalkylammonium compounds exhibited significant clearance. Rapid clearance was observed for N,N-dimethylalkylamines, and slower rates of clearance were measured for N-methylalkylamine analogs. Clearance rates for primary alkylamines were generally close to or below detectable levels. For the N-methylalkylamines and N,N-dimethylalkylamines, the highest CLint values were measured for C10 -C12 homologs; substantially lower clearance rates were observed for homologs containing shorter or longer carbon chains. Based on its cofactor dependency, biotransformation of C12 -N,N-dimethylamine appears to involve one or more cytochrome P450-dependent reaction pathways, and sulfonation. On a molar basis, N-demethylation metabolites accounted for up to 25% of the N,N-dimethylalkylamines removed during the 2-h assay, and up to 55% of the removed N-methylalkylamines. These N-demethylation products possess greater metabolic stability in the RT-S9 assay than the parent structures from which they derive and may contribute to the overall risk of ionizable alkylamines. The results of these studies provide a set of consistently determined CLint values that may be extrapolated to whole trout to inform in silico bioaccumulation assessments. Environ Toxicol Chem 2021;40:3123-3136. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Real-world experience with intravaginal culture using INVOCELL: an alternative model for infertility treatment.

OBJECTIVE: To describe the current practice indications, methodology, and outcomes from a real-world experience of intravaginal culture (IVC) using INVOCELL. DESIGN: A descriptive study outlining real-world experience with INVOCELL that addresses patient selection, ovarian stimulation, embryology laboratory practices, and outcomes. SETTING: Five fertility centers in Missouri, Texas, North Carolina, South Carolina, and Virginia. PATIENTS: Four hundred sixty-three patients undergoing 526 cycles. INTERVENTION: IVC using INVOCELL. MAIN OUTCOME MEASURES: Cumulative pregnancy rate and live births. Secondary outcomes of interest included percent good quality embryos. RESULTS: IVC with INVOCELL was primarily used in women <38 years with anti-Mullerian hormone level >0.8 ng/mL. The mean numbers of retrieved oocytes ranged from 9.2 to 16. Mean numbers of oocytes and sperm-injected oocytes loaded per INVOCELL ranged from a mean of 6.4-9.5 with a reported maximum of 34 oocytes loaded into the device. Most (95%) of the embryos were transferred on day 5. The mean blastocyst recovery per oocyte loaded into the device ranged from 19% to 34%; mean cumulative live birth plus ongoing pregnancy rates ranged from 29% to 53% per cycle start and 40% to 61% per transfer. CONCLUSIONS: This study of IVC using INVOCELL as an alternative model for infertility treatment confirms its utility as a viable alternative to standard incubator-based in vitro fertilization. The technology is compatible within the current framework of practice patterns and, when appropriately used, results in acceptable blastocyst recovery and live birth rates. Further use of INVOCELL in other clinical situations is warranted.

A Novel Multispecies Toxicokinetic Modeling Approach in Support of Chemical Risk Assessment.

Standardized laboratory tests with a limited number of model species are a key component of chemical risk assessments. These surrogate species cannot represent the entire diversity of native species, but there are practical and ethical objections against testing chemicals in a large variety of species. In previous research, we have developed a multispecies toxicokinetic model to extrapolate chemical bioconcentration across species by combining single-species physiologically based toxicokinetic (PBTK) models. This "top-down" approach was limited, however, by the availability of fully parameterized single-species models. Here, we present a "bottom-up" multispecies PBTK model based on available data from 69 freshwater fishes found in Canada. Monte Carlo-like simulations were performed using statistical distributions of model parameters derived from these data to predict steady-state bioconcentration factors (BCFs) for a set of well-studied chemicals. The distributions of predicted BCFs for 1,4-dichlorobenzene and dichlorodiphenyltrichloroethane largely overlapped those of empirical data, although a tendency existed toward overestimation of measured values. When expressed as means, predicted BCFs for 26 of 34 chemicals (82%) deviated by less than 10-fold from measured data, indicating an accuracy similar to that of previously published single-species models. This new model potentially enables more environmentally relevant predictions of bioconcentration in support of chemical risk assessments.

Folates, folic acid and preconception care - a review.

The link between folate deficiency and congenital spina bifida defects was first suggested in the 1960s. Although the prevention of these defects by preconception folic acid supplementation was confirmed in a large multi-centre controlled trial in 1991, its subsequent implementation as health education advice has made very little difference. North America's policy of folic acid fortification of flour and bread has had a beneficial impact. No European country has implemented fortification due to concern over possible adverse effects on older subjects, but a recent review shows these to be largely hypothetical and far outweighed by beneficial effects. Recent research by Menezo et al. has, however, shown that folic acid is ineffective for some women with severe fertility problems including recurrent miscarriage and failed in vitro fertilisation. There is a genetically determined bottleneck (677TT) in their folate metabolism that can be successfully overridden by going straight to the next step in the metabolic pathway and taking 5-methylytetrahydrofolate, as a preconception supplement. Menezo suggests that all women with fertility problems should be tested for 677TT. If fortification of flour and bread is to be implemented in the UK, there should be monitoring for possible adverse effects including the incidence of colorectal cancers and cognitive decline. In conclusion, whilst there are concerns that fortification could have a detrimental effect on these conditions, there is sound evidence that it would have much greater beneficial effects.

Evaluation and comparison of in vitro intrinsic clearance rates measured using cryopreserved hepatocytes from humans, rats, and rainbow trout.

In vitro and in silico methods that can reduce the need for animal testing are being used with increasing frequency to assess chemical risks to human health and the environment. The rate of hepatic biotransformation is an important species-specific parameter for determining bioaccumulation potential and extrapolating in vitro bioactivity to in vivo effects. One approach to estimating hepatic biotransformation is to employ in vitro systems derived from liver tissue to measure chemical (substrate) depletion over time which can then be translated to a rate of intrinsic clearance (CLint). In the present study, cryopreserved hepatocytes from humans, rats, and rainbow trout were used to measure CLint values for 54 industrial and pesticidal chemicals at starting test concentrations of 0.1 and 1 µM. A data evaluation framework that emphasizes the behavior of Heat-Treated Controls (HTC) was developed to identify datasets suitable for rate reporting. Measured or estimated ("greater than" or "less than") CLint values were determined for 124 of 226 (55 %) species-chemical-substrate concentration datasets with acceptable analytical chemistry. A large percentage of tested chemicals exhibited low HTC recovery values, indicating a substantial abiotic loss of test chemical over time. An evaluation of KOW values for individual chemicals suggested that in vitro test performance declined with increasing chemical hydrophobicity, although differences in testing devices for mammals and fish also likely played a role. The current findings emphasize the value of negative controls as part of a rigorous approach to data quality assessment for in vitro substrate depletion studies. Changes in current testing protocols can be expected to result in the collection of higher quality data. However, poorly soluble chemicals are likely to remain a challenge for CLint determination.

Designing QSARs for Parameters of High-Throughput Toxicokinetic Models Using Open-Source Descriptors.

The intrinsic metabolic clearance rate (Clint) and the fraction of the chemical unbound in plasma (fup) serve as important parameters for high-throughput toxicokinetic (TK) models, but experimental data are limited for many chemicals. Open-source quantitative structure-activity relationship (QSAR) models for both parameters were developed to offer reliable in silico predictions for a diverse set of chemicals regulated under the U.S. law, including pharmaceuticals, pesticides, and industrial chemicals. As a case study to demonstrate their utility, model predictions served as inputs to the TK component of a risk-based prioritization approach based on bioactivity/exposure ratios (BERs), in which a BER < 1 indicates that exposures are predicted to exceed a biological activity threshold. When applied to a subset of the Tox21 screening library (6484 chemicals), we found that the proportion of chemicals with BER <1 was similar using either in silico (1133/6484; 17.5%) or in vitro (148/848; 17.5%) parameters. Further, when considering only the chemicals in the Tox21 set with in vitro data, there was a high concordance of chemicals classified with either BER <1 or >1 using either in silico or in vitro parameters (767/848, 90.4%). Thus, the presented QSARs may be suitable for prioritizing the risk posed by many chemicals for which measured in vitro TK data are lacking.

Addition of Phenylmethylsulfonyl Fluoride Increases the Working Lifetime of the Trout Liver S9 Substrate Depletion Assay, Resulting in Improved Detection of Low Intrinsic Clearance Rates.

The activity of a trout liver S9 substrate depletion assay has been shown to decline over time, presumably due to proteolytic degradation of biotransformation enzymes. To address this problem, assay performance was evaluated following the addition of phenylmethylsulfonyl fluoride (PMSF) or a general-purpose protease inhibitor cocktail to liver homogenization buffers and/or S9 reaction mixtures. Addition of PMSF to liver homogenization buffers and/or S9 reaction mixtures had little or no effect on clearance of phenanthrene, a model cytochrome P450 substrate, in short-term (25 or 30 min) depletion experiments but resulted in significant improvements in retention of this initial activity over time. The protease inhibitor cocktail strongly inhibited initial activity when added to homogenization buffers or reaction mixtures. Taking into consideration potential effects on liver carboxylesterases, the treatment approach determined to be optimal was addition of 10 µM PMSF to the S9 reaction mixture. Addition of 10 µM PMSF to the mixture resulted in significantly higher rates of phenanthrene clearance in 2-h incubations relative to those obtained in the absence of PMSF and a 6-fold increase in the working lifetime of the preparation. The results of a statistical power analysis suggest that by increasing the working lifetime of the assay, addition of PMSF to the reaction mixture could result in substantially improved detection of low in vitro clearance rates when compared to current practice. These findings demonstrate the value of adding PMSF to the trout S9 preparation and may have broad implications for use of this assay to support chemical bioaccumulation assessments for fish. Environ Toxicol Chem 2021;40:148-161. © 2020 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.