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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

LncRNA MALAT1 is up-regulated in diabetic gastroparesis and involved in high-glucose-induced cellular processes in human gastric smooth muscle cells

Highlights: • MALAT1 was dysregulated in rat model of DGP and the samples from patients from diabetic patients with DGP symptoms. • MALAT1 played key role in the cellular processes in human gastric SMCs. • MALAT1 involved in the function of high-glucose treatments in human gastric SMCs. Recent years, widespread long non-coding RNAs (lncRNAs) were identified and known as regulator of gene expression. Diabetic gastroparesis (DGP) is one of the most common chronic complications of diabetes mellitus. There was no research reported the role of lncRNAs in DGP. In this study, we firstly established a rat model of DGP by STZ injection. Then, we detected the expression of MALAT1 and found that expression of MALAT1 was up-regulated in rat model of DGP, comparing to the control group (P < .01). Furthermore, we revealed that MALAT1 expression was increased in the samples from diabetic patients with DGP symptoms, in comparison with the control. In addition, we demonstrated that the inhibition of MALAT1 increased the expression of α-SMA and SM myosin heavy chains, reduced the cell viability, inhibited the potential of cell migration and induced cell apoptosis in human gastric smooth muscle cells (SMCs). Ultimately, we found that the regulation of MALAT1 expression modulated the function of high-glucose stimulation in human gastric SMCs. Therefore, our study firstly indicated that MALAT1 was up-regulated in DGP and played an important role in the pathogenesis of DGP.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

TGF beta inhibits expression of SP-A, SP-B, SP-C, but not SP-D in human alveolar type II cells

Highlights: • TGF beta inhibits expression of SP-A, SP-B, SP-C, Fatty acid synthase, and ABCA3. • TGF beta does not inhibit the expression of SP-D. • TGF beta does not induce EMT changes in highly differentiated type II cells. TGF beta is a multifunctional cytokine that regulates alveolar epithelial cells as well as immune cells and fibroblasts. TGF beta inhibits surfactant protein A, B and C expression in fetal human lung and can inhibit type II cell proliferation induced by FGF7 (KGF). However, little is known about direct effects of TGF beta on adult human type II cells. We cultured alveolar type II cells under air/liquid interface conditions to maintain their state of differentiation with or without TGF beta. TGF beta markedly decreased expression of SP-A, SP-B, SP-C, fatty acid synthase, and the phospholipid transporter ABCA3. However, TGF beta increased protein levels of SP-D with little change in mRNA levels, indicating that it is regulated independently from other components of surfactant. TGF beta is a negative regulator of both the protein and the phospholipid components of surfactant. TGF beta did not induce EMT changes in highly differentiated human type II cells. SP-D is an important host defense molecule and regulated independently from the other surfactant proteins. Taken together these data are the first report of the effect of TGF beta on highly differentiated adult human type II cells. The effects on the surfactant system are likely important in the development of fibrotic lung diseases.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Comparative characterization of stem cells from human exfoliated deciduous teeth, dental pulp, and bone marrow–derived mesenchymal stem cells

Highlights: • We compared the in vitro characteristics of dental pulp stem cells from deciduous teeth (SHED), human dental pulp stem cells (hDPSCs), and human bone marrow mesenchymal stem cells (hBMSCs). • SHED exhibit greater proliferative potential than hDPSCs and hBMSCs. • SHED exhibited higher proliferative activity and levels of bFGF and BMP-2 gene expression compared with BMMSCs and DPSCs. The ease of harvesting cells and ability to avoid invasive surgical procedures suggest that SHED may be a useful cell source for application in bone regeneration treatments. Mesenchymal stem cells (MSCs) are used clinically in tissue engineering and regenerative medicine. The proliferation and osteogenic differentiation potential of MSCs vary according to factors such as tissue source and cell population heterogeneity. Dental tissue has received attention as an easily accessible source of high-quality stem cells. In this study, we compared the in vitro characteristics of dental pulp stem cells from deciduous teeth (SHED), human dental pulp stem cells (hDPSCs), and human bone marrow mesenchymal stem cells (hBMSCs).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Tumor-dependent secretion of close homolog of L1 results in elevation of its circulating level in mouse model for human lung tumor

Highlights: • CHL1 was secreted with truncated and exosomal form from primary lung tumor cells. • A mouse model for human lung tumor showed elevated circulating levels of CHL1. • The circulating CHL1 was increased in tumor size-dependent manner. • It suggests CHL1 is a potential indicator for tumor progression in human lung tumor. Close homolog of L1 (CHL1) and its truncated form mainly play crucial roles in mouse brain development and neural functions. Herein, we newly identified that truncated form of CHL1 is produced and released from lung tumor tissue in a mouse model expressing human EML4-ALK fusion gene. Both western blot and direct ELISA analysis revealed that mouse CHL1 level in serum (including serum extracellular vesicles) was significantly elevated in EML4-ALK transgenic mice. The correlation between the tumor size and the amount of CHL1 secretion could be examined in this study, and showed a significant positive correlation in a tumor size-dependent manner. Considering these results, the measurement of circulating CHL1 level may contribute to assess a tumor progression in human lung tumor patients.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

The HMW2 adhesin of non-typeable Haemophilus influenzae is a human-adapted lectin that mediates high-affinity binding to 2–6 linked N-acetylneuraminic acid glycans

Non-typeable Haemophilus influenzae (NTHi) is a human-adapted bacterial pathogen, responsible for infections of the human respiratory tract. This pathogen expresses a range of adhesins that mediate binding to host cells. Most NTHi strains can express the related adhesins HMW1 and HMW2. Expression of HMW proteins is phase-variable: changes in the length of simple-sequence repeats located in the encoding genes promoter regions results in changes in expression levels of these adhesins. HMW expression is also controlled by epigenetic regulation. HMW1 has been previously demonstrated to bind α 2–3 sialyl-lactosamine, but affinity of this interaction has not been investigated. The host receptor(s) for HMW2 is currently unknown. We hypothesized that host glycans may act as receptors for HMW2-mediated adherence. We examined the glycan-binding activity of HMW2 using glycan arrays and Surface Plasmon Resonance (SPR). These studies demonstrate that HMW2 binds 2–6 linked N-acetylneuraminic acid with high affinity. HMW2 did not bind glycan structures containing the non-human form of sialic acid, N-glycolylneuraminic acid. Thus, the specificity of HMW1 and HMW2 have complementary lectin activities that may allow NTHi distinct niches in the human host.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

microRNA-124a suppresses PHF19 over-expression, EZH2 hyper-activation, and aberrant cell proliferation in human glioma

Highlights: • We examined the role of PHD Finger Protein 19 (PHF19) in human glioma. • PHF19 was upregulated in glioma tumors, correlating with miR-124a downregulation. • miR-124a suppressed PHF19 expression, EZH2 activation, and cell proliferation. • PHF19 knockdown suppressed EZH2 activation and glioma cell proliferation. • Xenograft tumor growth was inhibited by miRNA-124a or PHF19 shRNA. Enhancer of Zeste 2 (EZH2) is the key enzymatic factor in Polycomb Repressive Complex 2 (PRC2), a transcriptional repressor which contributes to oncogenesis. Recent research has revealed the key role of aberrant EZH2 hyper-activity in human gliomas. Here, we examined the role of the lesser-known PRC2-associated PHD Finger Protein 19 (PHF19) in human glioma. We found that PHF19 transcript and protein levels were significantly elevated in human glioma tumors, which was negatively associated with expression of the anti-PHF19 microRNA miR-124a. miR-124a over-expression in the A172 and U251MG glioma cell lines and patient glioma cells suppressed PHF19 expression, EZH2 activation, and cell proliferation. However, miR-124a did not suppress cell proliferation with PHF19 silencing or mutation. Knockdown of PHF19 suppressed EZH2 phosphorylation and proliferation of glioma cells. Co-immunoprecipitation confirmed that PHF19 forms the PRC2 with EZH2, EED, and SUZ12. In a nude murine model, subcutaneous and orthotopic xenograft tumor growth was significantly inhibited by miRNA-124a or PHF19 shRNA. In conclusion, miR-124a suppresses PHF19 over-expression, EZH2 hyper-activation, and aberrant glioma cell proliferation. Targeting PHF19 via miR-124a agomir therapy may block aberrant EZH2 hyper-activity in these tumors.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Leflunomide attenuates oxidative stress in fetal human lung endothelial cells via superoxide dismutase 2 and catalase

Highlights: • Leflunomide decreases oxidative stress in fetal human lung endothelial cells. • Leflunomide induces catalase, NQO1, and SOD2 enzymes in fetal human lung cells. • Leflunomide effects on oxidative stress, catalase, and SOD2 are AhR-independent. • AhR deficiency abrogates leflunomide-mediated induction of NQO1 enzyme. Hyperoxia-induced oxidative stress contributes to the pathogenesis of bronchopulmonary dysplasia (BPD), the most common respiratory morbidity of preterm infants. Importantly, the disease lack specific therapies and is associated with long-term cardio-pulmonary and neurodevelopmental morbidities, signifying the need to discover novel therapies and decrease the disease burden. We and others have demonstrated that leflunomide, a food and drug administration approved drug to treat humans with rheumatoid arthritis, increases the expression of the anti-oxidant enzymes, NAD(P)H quinone dehydrogenase 1 (NQO1), catalase, and superoxide dismutase (SOD). However, whether this drug can decrease oxidative stress in fetal human pulmonary arterial endothelial cells (HPAECs) is unknown. Therefore, we tested the hypothesis that leflunomide will decrease hyperoxia-induced oxidative stress by upregulating these anti-oxidant enzymes in HPAECs. Leflunomide decreased hydrogen peroxide (H{sub 2}O{sub 2}) levels and increased the mRNA and protein levels of catalase, NQO1, and SOD2 in HPAECs at basal conditions. Further, leflunomide-treated cells continued to have decreased H{sub 2}O{sub 2} and increased SOD2 levels upon hyperoxia exposure. Leflunomide did not affect the expression of other anti-oxidant enzymes, including hemoxygenase-1 and SOD1. AhR-knockdown experiments suggested that leflunomide regulated NQO1 levels via AhR-dependent mechanisms and H{sub 2}O{sub 2}, catalase, and SOD2 levels via AhR-independent mechanisms. Collectively, the results support the hypothesis that leflunomide decreases oxidative stress in HPAECs via SOD2-and catalase-dependent, but AhR- and NQO1-independent mechanisms. Our findings indicate that leflunomide is a potential drug for the management of BPD in preterm infants.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Inhibitory effect of celastrol on adipogenic differentiation of human adipose-derived stem cells

Highlights: • Celastrol has therapeutic potential against obesity- and aging-related diseases. • Anti-adipogenic effect of celatrol in human ADSCs depended on dose and duration. • Celatrol inhibited adipogenesis in human ADSCs by regulating PPARG and CEBPA. • Celastrol inhibited adipogenesis in hADSCs derived from 12 donors with various ages. • Celastrol also inhibited osteogenic and chondrogenic differentiation in hADSCs. Control of adipogenesis in mesenchymal stem cells (MSCs) offers enormous potential for management of obesity- and aging-related diseases. Celastrol, the traditional Chinese medicine extracted from Tripterygium wilfordi, exhibits anti-obesity effects in in vitro and in vivo murine models. This study describes how celastrol affects multilineage differentiation potential of human adipose-derived stem cells (hADSCs). We performed in vitro adipogenic differentiation of hADSCs and investigated how celastrol-induced lipid accumulation and expression of adipocyte differentiation markers varied with dose, duration, and donor age. In addition, we assessed the effect of celastrol on osteogenic and chondrogenic differentiation of hADSCs. During adipogenic induction of hADSCs, the inhibitory effect of celastrol on lipid accumulation and adipogenesis depended on dose, duration, time of administration, and individual donor. Inhibition was mediated by proliferator-activated receptor-γ (PPARG) and CCAAT/enhancer-binding protein alpha (CEBPA). Celastrol also suppressed differentiation of hADSCs into the osteogenic and chondrogenic lineages. Celastrol plays a regulatory role in multilineage differentiation of human MSCs. Our findings provide important insights regarding management of obesity and stem cell therapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Comprehensive In Vivo Interrogation Reveals Phenotypic Impact of Human Enhancer Variants

Establishing causal links between non-coding variants and human phenotypes is an increasing challenge. In this paper, we introduce a high-throughput mouse reporter assay for assessing the pathogenic potential of human enhancer variants in vivo and examine nearly a thousand variants in an enhancer repeatedly linked to polydactyly. We show that 71% of all rare non-coding variants previously proposed as causal lead to reporter gene expression in a pattern consistent with their pathogenic role. Variants observed to alter enhancer activity were further confirmed to cause polydactyly in knockin mice. We also used combinatorial and single-nucleotide mutagenesis to evaluate the in vivo impact of mutations affecting all positions of the enhancer and identified additional functional substitutions, including potentially pathogenic variants hitherto not observed in humans. Our results uncover the functional consequences of hundreds of mutations in a phenotype-associated enhancer and establish a widely applicable strategy for systematic in vivo evaluation of human enhancer variants.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Comprehensive proteomics analysis of stressed human islets identifies GDF15 as a target for type 1 diabetes intervention

Type 1 diabetes results from the progressive loss of beta cells, a process propagated by pro-inflammatory cytokine signaling that disrupts the balance between the expression of pro- and anti-apoptotic proteins. To identify such proteins, we performed comprehensive proteomics of human pancreatic islets treated with interleukin-1ß and interferon-?, leading to the identification of 11,325 proteins, of which 387 were significantly regulated by treatment. We then tested the function of growth/differentiation factor 15 (GDF15), which was repressed by the cytokine treatment. We found that GDF15 translation was blocked during inflammation, while the addition of exogenous GDF15 inhibited interleukin-1ß/interferon-?-induced apoptosis of human islets and a human beta-cell line. Furthermore, administration of GDF15 significantly decreased insulitis in NOD mice. Our approach provides a unique resource for the identification of the human islet proteins regulated by cytokines and was effective in discovering a potential target for type 1 diabetes therapy.

Nakayasu, Ernesto S.↗
DOE OSTI2017

Cadmium, lead, and arsenic contamination in paddy soils of a mining area and their exposure effects on human HEPG2 and keratinocyte cell-lines

A mining district in south China shows significant metal(loid) contamination in paddy fields. In the soils, average Pb, Cd and As concentrations were 460.1, 11.7 and 35.1 mg kg{sup −1} respectively, which were higher than the environmental quality standard for agricultural soils in China (GB15618-1995) and UK Clea Soil Guideline Value. The average contents of Pb, Cd and As in rice were 5.24, 1.1 and 0.7 mg kg{sup −1} respectively, which were about 25, 4.5 or 2.5 times greater than the limit values of the maximum safe contaminant concentration standard in food of China (GB 2762-2012), and about 25, 10 or 1 times greater than the limit values of FAO/WHO standard. The elevated contents of Pb, Cd and As detected in soils around the factories, indicated that their spatial distribution was influenced by anthropogenic activity, while greater concentrations of Cd in rice appeared in the northwest region of the factories, indicating that the spatial distribution of heavy metals was also affected by natural factors. As human exposure around mining districts is mainly through oral intake of food and dermal contact, the effects of these metals on the viability and MT protein of HepG2 and KERTr cells were investigated. The cell viability decreased with increasing metal concentrations. Co-exposure to heavy metals (Pb+Cd) increased the metals (Pb or Cd)-mediated MT protein induction in both human HepG2 and KERTr cells. Increased levels of MT protein will lead to greater risk of carcinogenic manifestations, and it is likely that chronic exposure to metals may increase the risk to human health. Nevertheless, when co-exposure to two or more metals occur (such as As+Pb), they may have an antagonistic effect thus reducing the toxic effects of each other. Capsule: Metal contaminations in paddy soils and rice were influenced by anthropogenic activity; metal co-exposure induced MT protein in human cells. - Highlights: • Pb, Cd and As in paddy soils and rice were higher than national and FAO standards. • Pb, Cd and As spatial distribution was mainly influenced by anthropogenic activity. • The HepG2 and KERTr cell viability decreased with increasing metal concentrations. • Co-exposure to heavy metals increased MT protein induction in HepG2 and KERTr cells. • Co-exposure to some metals (As+Pb) may have an antagonistic effect.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Influence of chronic low-dose/dose-rate high-LET irradiation from radium-226 in a human colorectal carcinoma cell line

Purpose: To evaluate potential damages of chronic environmentally relevant low-dose/dose-rate high-LET irradiation from a naturally occurring alpha-emitting radionuclide (radium-226, {sup 226}Ra) on a human colorectal carcinoma HCT116 p53{sup +/+} cell line. Methods: Clonogenic survival assays and mitochondrial membrane potential (MMP) measurement with a sensitive fluorescent MMP probe JC-1 were performed in HCT116 p53{sup +/+} cells chronically exposure to low doses/dose rates of {sup 226}Ra with high-LET. Comparisons were made with the human non-transformed keratinocyte HaCaT cell line and acute low-dose direct low-LET gamma radiation. Results and conclusion: The chronic low-dose/dose-rate alpha radiation (CLD/DRAR) did not reduce the clonogenic survival of HCT116 p53{sup +/+} cells over the period of 70 days of exposure. Only one significant reduction in the HCT116 p53{sup +/+} cells’ clonogenic survival was when cells were grown with 10,000 mBq/mL {sup 226}Ra for 40 days and progeny cells were clonogenically assessed in the presence of 10,000 mBq/mL {sup 226}Ra. The cumulative doses that cells received during this period ranged from 0.05 to 46.2 mGy. The mitochondrial membrane potential (MMP) dropped initially in both HCT116 p53{sup +/+} and HaCaT cells in response to CLD/DRAR. The MMP in HCT116 p53{sup +/+} cells recovered more quickly at all dose points than and that in HaCaT cells until the end of the exposure period. The highest dose rate of 0.66 mGy/day depolarized the HaCaT's mitochondria more consistently during the exposure period. The faster recovery status of the MMP in HCT116 p53{sup +/+} cells than that in HaCaT cells was also observed after exposure to acute low-dose gamma rays. Overall, it was found that CLD/DRAR had little impact on the MMP of human colorectal cancer and keratinocyte cell lines. - Highlights: • Human colorectal carcinoma HCT116 p53{sup +/+} and keratinocyte HaCaT cells were exposed to chronic low-dose/dose-rate alpha radiation (CLD/DRAR). • Unlike the HaCaT cells, HCT116 p53{sup +/+} cells’ clonogenic survival and mitochondrial membrane potential (MMP) changed little upon CLD/DRAR. • Upon the mitochondrial membrane depolarization response induced by CLD/DRAR, HaCaT cells were more sensitive than HCT116 p53{sup +/+}. • Gamma radiation depolarized the mitochondria of both HaCaT and HCT116 p53{sup +/+} in a dose-dependent manner. • The MMP in HCT116 p53{sup +/+} could recover more quickly than that in HaCaT cells after an acute low-dose gamma irradiation challenge.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Ecological and human exposure assessment to PBDEs in Adige River

Highlights: • Exposure assessment of aquatic species in Adige river to PBDEs Population exposure to PBDEs due to contaminated freshwater fish ingestion. • Use of MERLIN-Expo model for integrated exposure assessment. • Comparability between simulated and real PBDEs concentrations in aquatic species. • Different exposure trends to PBDEs were observed for children, adolescent, adult and elderly. The interest for environmental issues and the concern resulting from the potential exposure to contaminants were the starting point to develop methodologies in order to evaluate the consequences that those might have over both the environment and human health. Considering the feature of POPs, including PBDEs, such as bioaccumulation, biomagnification, long-range transport and adverse effects even long time after exposure, risk assessment of POPs requires specific approaches and tools. In this particular context, the MERLIN-Expo tool was used to assess the aquatic environmental exposure of Adige River to PBDEs and the accumulation of PBDEs in humans through the consumption of possible contaminated local aquatic food. The aquatic food web models provided as output of the deterministic simulation the time trend of concentrations for twenty years of BDE-47 and total PBDEs, expressed using the physico-chemical properties of BDE-47, in aquatic organisms of the food web of Adige River. For BDE-47, the highest accumulated concentrations were detected for two benthic species: Thymallus thymallus and Squalius cephalus whereas the lowest concentrations were obtained for the pelagic specie Salmo trutta marmoratus. The trend obtained for the total PBDEs, calculated using the physico-chemical properties of BDE-47, follows the one of BDE-47. For human exposure, different BDE-47 and total PBDEs concentration trends between children, adolescent, adults and elderly were observed, probably correlated with the human intake of fish products in the daily diet and the ability to metabolize these contaminants. In detail, for the adolescents, adults and elderly a continuous accumulation of the target contaminants during the simulation's years was observed, whereas for children a plateau at the end of the simulation period was perceived.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Cytotoxicity measurement of Bisphenol A (BPA) and its substitutes using human keratinocytes

Highlights: • BPA has been widely used in many plastic products despite it might be harmful to human health. • Many alternatives developed lack sufficient toxicity assessment. • BPA showed significantly higher cytotoxicity than its five substitutes. • CHDM and TPA might be suitable substitutes to replace BPA. Bisphenol-A (BPA) was first synthesized in the 1890s and has been used in many plastic products. However, BPA is known to act as an endocrine disruptor and has been found to be toxic to human health. Many alternative substances have been developed to replace BPA, but it is still widely used worldwide. In this study, we identified the potential cytotoxicity of BPA by evaluating toxicity using human keratinocytes. Also, we evaluated cytotoxicity of BPA substitutes to determine their suitability as an alternative to BPA. The proliferation assay using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, flow cytometry and western blot analysis showed that BPA significantly affect cell viability, induction of apoptotic fraction and increased activation of DNA-damage marker protein. In addition, through the same experiments, the substitutes of BPA were shown to be significantly less toxic than BPA, and the least toxicity was observed with 1,4-cyclohexanedimethanol (CHDM) and terephthalic acid (TPA). In conclusion, this study suggests that cytotoxicity of BPA induces apoptosis of human keratinocytes, and that CHDM and TPA are the most suitable substitutes for BPA.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Modeling of inertial deposition in scaled models of rat and human nasal airways: Towards in vitro regional dosimetry in small animals

Rodents are routinely used in inhalation toxicology tests as human surrogates. However, in vitro dosimetry tests in rodent casts are still scarce due to small rodent airways and in vitro tests to quantify sub-regional dosimetry are still impractical. We hypothesized that for inertial particles whose deposition is dominated by airflow convection (Reynolds number) and particle inertia (Stokes number), the deposition should be similar among airway replicas of different scales if their Reynolds and Stokes numbers are kept the same. In this study, we aimed to (1) numerically test the hypothesis in three airway geometries: a USP induction port, a human nose model, and a Sprague-Dawley rat nose model, and (2) find the range of applicability of this hypothesis. Five variants of the USP and human nose models and three variants of the rat nose model were tested. Inhalation rates and particle sizes were scaled to match the Reynolds number and Stokes numbers. A low-Reynolds-number k–ω model was used to resolve the airflow and a Lagrangian tracking algorithm was used to simulate the particle transport and deposition. Statistical analysis of predicted doses was conducted using ANOVA. For normal inhalation rates and particle dia- meters ranging from 0.5 to 24 mm, the deposition differences between the life-size and scaled models are insignificant for all airway geometries considered (i.e., human nose, USP, and rat nose). Furthermore, the deposition patterns and exit particle profiles also look similar among scaled models. However, deposition rates and patterns start to deviate if inhalation rates are too low, or particle sizes are too large. For the rat nose, the threshold velocity was found to be 0.71 m/s and the threshold Froude number to be 50. Results of this study provide a theoretical foundation for sub-regional in vitro dosimetry tests in small animals and for interpretation of data from inter-species or intra-species with varying body sizes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Discovery and Characterization of FMN-Binding β-Glucuronidases in the Human Gut Microbiome

The human gut microbiota encodes β-glucuronidases (GUSs) that play key roles in health and disease via the metabolism of glucuronate-containing carbohydrates and drugs. Hundreds of putative bacterial GUS enzymes have been identified by metagenomic analysis of the human gut microbiome, but less than 10% have characterized structures and functions. Here in this paper we describe a set of unique gut microbial GUS enzymes that bind flavin mononucleotide (FMN). First, we show using mass spectrometry, isothermal titration calorimetry, and x-ray crystallography that a purified GUS from the gut commensal microbe Faecalibacterium prausnitzii binds to FMN on a surface groove located 30 Å away from the active site. Second, utilizing structural and functional data from this FMN-binding GUS, we analyzed the 279 unique GUS sequences from the Human Microbiome Project database and identified 14 putative FMN-binding GUSs. We characterized four of these hits and solved the structure of two, the GUSs from Ruminococcus gnavus and Roseburia hominis, which confirmed that these are FMN binders. Third, binding and kinetic analysis of the FMN-binding site mutants of these five GUSs show that they utilize a conserved site to bind FMN that is not essential for GUS activity, but can affect KM. Lastly, a comprehensive structural review of the PDB reveals that the FMN-binding site employed by these enzymes is unlike any structurally characterized FMN binders to date. These findings reveal the first instance of an FMN-binding glycoside hydrolase and suggest a potential link between FMN and carbohydrate metabolism in the human gut microbiota.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Evaluation of a rapid, generic human gestational dose model

Chemical risk assessment considers potentially susceptible populations including pregnant women and developing fetuses. Humans encounter thousands of chemicals in their environments, few of which have been fully characterized. Toxicokinetic (TK) information is needed to relate chemical exposure to potentially bioactive tissue concentrations. Observational data describing human gestational exposures are unavailable for most chemicals, but physiologically based TK (PBTK) models estimate such exposures. Development of chemical-specific PBTK models requires considerable time and resources. As an alternative, generic PBTK approaches describe a standardized physiology and characterize chemicals with a set of standard physical and TK descriptors – primarily plasma protein binding and hepatic clearance. Here we report and evaluate a generic PBTK model of a human mother and developing fetus. We used a published set of formulas describing the major anatomical and physiological changes that occur during pregnancy to augment the High-Throughput Toxicokinetics (httk) software package. We simulated the ratio of concentrations in maternal and fetal plasma and compared to literature in vivo measurements. We evaluated the model with literature in vivo time-course measurements of maternal plasma concentrations in pregnant and non-pregnant women. Finally, we prioritized chemicals measured in maternal serum based on predicted fetal brain concentrations. This new model can be used for TK simulations of 859 chemicals with existing human-specific in vitro TK data as well as any new chemicals for which such data become available. Furthermore, this gestational model may allow for in vitro to in vivo extrapolation of point of departure doses relevant to reproductive and developmental toxicity.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Human reliability analysis studies from simulator experiments using Bayesian inference

Probabilistic Safety Assessment (PSA) of complex facilities is performed to arrive at the risk posed by them. PSA also accounts for the contribution of the human errors towards the overall risk through Human Reliability Analysis (HRA) in terms of Human Error Probability (HEP). Human operators are part of the system and do not work in isolation. Their performance is influenced by the context in which the actions are performed. As a result, quantification of HEP requires operator performance data under the given context. Some good sources of operator performance data are plant‘s operation data, simulator data and expert judgement. The plant operation data pertaining to HRA is generally sparse. In this situation, a full scope plant simulator provides a good alternative for operator performance data generation. Many of the currently practiced HRA methods have been developed by combining the empirical evidence with expert judgement and contain a lot of uncertainty in their estimates. Bayesian inference is suitable for updating the prior HRA estimates with the simulator evidence to obtain the posterior HEP. Here, posterior HEP has been calculated for postulated accident scenarios in advanced reactor (first of its kind) at design stage, using plant simulator.

97 MATHEMATICS AND COMPUTING↗