A semi-automated system for quantifying the oxidative potential of ambient particles in aqueous extracts using the dithiothreitol (DTT) assay: results from the Southeastern Center for Air Pollution and Epidemiology (SCAPE)

Abstract. A variety of methods are used to measure the capability of particulate matter (PM) to catalytically generate reactive oxygen species (ROS) in vivo, also defined as the aerosol oxidative potential. A widely used measure of aerosol oxidative potential is the dithiothreitol (DTT) assay, which monitors the depletion of DTT (a surrogate for cellular antioxidants) as catalyzed by the redox-active species in PM. However, a major constraint in the routine use of the DTT assay for integrating it with the large-scale health studies is its labor-intensive and time-consuming protocol. To specifically address this concern, we have developed a semi-automated system for quantifying the oxidative potential of aerosol liquid extracts using the DTT assay. The system, capable of unattended analysis at one sample per hour, has a high analytical precision (Coefficient of Variation of 12% for standards, 4% for ambient samples), and reasonably low limit of detection (0.31 nmol min−1). Comparison of the automated approach with the manual method conducted on ambient samples yielded good agreement (slope = 1.08 ± 0.12, r2 = 0.92, N = 9). The system was utilized for the Southeastern Center for Air Pollution and Epidemiology (SCAPE) to generate an extensive data set on DTT activity of ambient particles collected from contrasting environments (urban, road-side, and rural) in the southeastern US. We find that water-soluble PM2.5 DTT activity on a per air volume basis was spatially uniform and often well correlated with PM2.5 mass (r = 0.49 to 0.88), suggesting regional sources contributing to the PM oxidative potential in southeast US. However, the greater heterogeneity in the intrinsic DTT activity (per PM mass basis) across seasons indicates variability in the DTT activity associated with aerosols from sources that vary with season. Although developed for the DTT assay, the instrument can also be used to determine oxidative potential with other acellular assays.

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A semi-automated system for quantifying the oxidative potential of ambient particles in aqueous extracts using the dithiothreitol (DTT) assay: results from the Southeastern Center for Air Pollution and Epidemiology (SCAPE)

Atmospheric Measurement Techniques ◽

10.5194/amt-8-471-2015 ◽

2015 ◽

Vol 8 (1) ◽

pp. 471-482 ◽

Cited By ~ 73

Author(s):

T. Fang ◽

V. Verma ◽

H. Guo ◽

L. E. King ◽

E. S. Edgerton ◽

...

Keyword(s):

Air Pollution ◽

Large Scale ◽

Limit Of Detection ◽

Water Soluble ◽

Automated System ◽

Oxidative Potential ◽

Data Set ◽

Ambient Particles ◽

Southeastern Us

Abstract. A variety of methods are used to measure the capability of particulate matter (PM) to catalytically generate reactive oxygen species (ROS) in vivo, also defined as the aerosol oxidative potential. A widely used measure of aerosol oxidative potential is the dithiothreitol (DTT) assay, which monitors the depletion of DTT (a surrogate for cellular antioxidants) as catalyzed by the redox-active species in PM. However, a major constraint in the routine use of the DTT assay for integrating it with large-scale health studies is its labor-intensive and time-consuming protocol. To specifically address this concern, we have developed a semi-automated system for quantifying the oxidative potential of aerosol liquid extracts using the DTT assay. The system, capable of unattended analysis at one sample per hour, has a high analytical precision (coefficient of variation of 15% for positive control, 4% for ambient samples) and reasonably low limit of detection (0.31 nmol min−1). Comparison of the automated approach with the manual method conducted on ambient samples yielded good agreement (slope = 1.08 ± 0.12, r2 = 0.92, N = 9). The system was utilized for the Southeastern Center for Air Pollution & Epidemiology (SCAPE) to generate an extensive data set on DTT activity of ambient particles collected from contrasting environments (urban, roadside, and rural) in the southeastern US. We find that water-soluble PM2.5 DTT activity on a per-air-volume basis was spatially uniform and often well correlated with PM2.5 mass (r = 0.49 to 0.88), suggesting regional sources contributing to the PM oxidative potential in the southeastern US. The correlation may also suggest a mechanistic explanation (oxidative stress) for observed PM2.5 mass-health associations. The heterogeneity in the intrinsic DTT activity (per-PM-mass basis) across seasons indicates variability in the DTT activity associated with aerosols from sources that vary with season. Although developed for the DTT assay, the instrument can also be used to determine oxidative potential with other acellular assays.

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Characterization and comparison of PM2.5 oxidative potential assessed by two acellular assays

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-5197-2020 ◽

2020 ◽

Vol 20 (9) ◽

pp. 5197-5210 ◽

Cited By ~ 3

Author(s):

Dong Gao ◽

Krystal J. Godri Pollitt ◽

James A. Mulholland ◽

Armistead G. Russell ◽

Rodney J. Weber

Keyword(s):

Metal Ions ◽

Water Soluble ◽

Metal Species ◽

Urban Site ◽

Chemical Components ◽

Linear Regression Models ◽

Oxidative Potential ◽

Metal Interactions ◽

Metal Metal

Abstract. The capability of ambient particles to generate in vivo reactive oxygen species (ROS), called oxidative potential (OP), is a potential metric for evaluating the health effects of particulate matter (PM) and is supported by several recent epidemiological investigations. Studies using various types of OP assays differ in their sensitivities to varying PM chemical components. In this study, we systematically compared two health-relevant acellular OP assays that track the depletion of antioxidants or reductant surrogates: (i) the synthetic respiratory-tract lining fluid (RTLF) assay that tracks the depletion of ascorbic acid (AA) and glutathione (GSH) and (ii) the dithiothreitol (DTT) assay that tracks the depletion of DTT. Yearlong daily samples were collected at an urban site in Atlanta, GA (Jefferson Street), during 2017, and both DTT and RTLF assays were performed to measure the OP of water-soluble PM2.5 components. PM2.5 mass and major chemical components, including metals, ions, and organic and elemental carbon were also analyzed. Correlation analysis found that OP as measured by the DTT and AA depletion (OPDTT and OPAA, respectively) were correlated with both organics and some water-soluble metal species, whereas that from the GSH depletion (OPGSH) was exclusively sensitive to water-soluble Cu. These OP assays were moderately correlated with each other due to the common contribution from metal ions. OPDTT and OPAA were moderately correlated with PM2.5 mass with Pearson's r=0.55 and 0.56, respectively, whereas OPGSH exhibited a lower correlation (r=0.24). There was little seasonal variation in the OP levels for all assays due to the weak seasonality of OP-associated species. Multivariate linear regression models were developed to predict OP measures from the particle composition data. Variability in OPDTT and OPAA were not only attributed to the concentrations of metal ions (mainly Fe and Cu) and organic compounds but also to antagonistic metal–organic and metal–metal interactions. OPGSH was sensitive to the change in water-soluble Cu and brown carbon (BrC), a proxy for ambient humic-like substances.

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Structure of the Séchilienne unstable slope from large-scale three-dimensional electrical tomography using a Resistivity Distributed Automated System (R-DAS)

Geophysical Journal International ◽

10.1093/gji/ggz259 ◽

2019 ◽

Vol 219 (1) ◽

pp. 129-147 ◽

Cited By ~ 2

Author(s):

M Lajaunie ◽

J Gance ◽

P Nevers ◽

J-P Malet ◽

C Bertrand ◽

...

Keyword(s):

Large Scale ◽

Electrical Potential ◽

Three Dimensional ◽

Automated System ◽

Data Uncertainty ◽

Complex Data ◽

Electrical Tomography ◽

Data Set ◽

Resistivity Model ◽

Unstable Slope

SUMMARY This work presents a 3-D resistivity model of the Séchilienne unstable slope acquired with a network of portable resistivimeters in summer 2017. The instrumentation consisted in distributed measuring systems (IRIS Instruments FullWaver) to measure the spatial variations of electrical potential. 23 V-FullWaver receivers with two 50 m dipoles have been deployed over an area of circa 2 km2; the current was injected between a fixed remote electrode and a mobile electrode grounded successively at 30 locations. The data uncertainty has been evaluated in relation to the accuracy of electrodes positioning. The software package BERT (Boundless Electrical Resistivity Tomography) is used to invert the apparent resistivity and model the complex data set providing the first 3-D resistivity model of the slope. Stability tests and synthetic tests are realized to assess the interpretability of the inverted models. The 3-D resistivity model is interpreted up to a depth of 500 m; it allows identifying resistive and conductive anomalies related to the main geological and hydrogeological structures shaping the slope. The high fracturation of the rock in the most active zone of the landslide appears as a resistive anomaly where the highest resistivity values are located close to the faults. A major drain formed by a fault in the unaltered micaschist is identified through the discharge of a perched aquifer along the conductive zone producing an important conductive anomaly contrasting with the unaltered micaschist.

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In Vivo Large Scale Mapping Of Protein Turnover In The Human Cerebrospinal Fluid

10.1101/710418 ◽

2019 ◽

Author(s):

Sylvain Lehmann ◽

Christophe Hirtz ◽

Jérôme Vialaret ◽

Maxence Ory ◽

Guillaume Gras Combes ◽

...

Keyword(s):

Cerebrospinal Fluid ◽

Drug Targets ◽

Large Scale ◽

Large Data ◽

Clinical Samples ◽

Sample Collection ◽

Data Set ◽

Disease Etiology ◽

System Physiology

SummaryThe extraction of accurate physiological parameters from clinical samples provides a unique perspective to understand disease etiology and evolution, including under therapy. We introduce a new proteomics framework to map patient proteome dynamics in vivo, either proteome wide or in large targeted panels. We applied it to ventricular cerebrospinal fluid (CSF) and could determine the turnover parameters of almost 200 proteins, whereas a handful were known previously. We covered a large number of neuron biology- and immune system-related proteins including many biomarkers and drug targets. This first large data set unraveled a significant relationship between turnover and protein origin that relates to our ability to investigate the central nervous system physiology precisely in future studies. Our data constitute a reference in CSF biology as well as a repertoire of peptides for the community to design new proteome dynamics analyses. The disclosed methods apply to other fluids or tissues provided sequential sample collection can be performed.

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Source apportionment of atmospheric PM10 oxidative potential: synthesis of 15 year-round urban datasets in France

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-11353-2021 ◽

2021 ◽

Vol 21 (14) ◽

pp. 11353-11378

Author(s):

Samuël Weber ◽

Gaëlle Uzu ◽

Olivier Favez ◽

Lucille Joanna S. Borlaza ◽

Aude Calas ◽

...

Keyword(s):

Source Apportionment ◽

Health Risks ◽

Biomass Burning ◽

Large Scale ◽

Road Traffic ◽

Urban Traffic ◽

Redox Activity ◽

Significant Activity ◽

Oxidative Potential

Abstract. Reactive oxygen species (ROS) carried or induced by particulate matter (PM) are suspected of inducing oxidative stress in vivo, leading to adverse health impacts such as respiratory or cardiovascular diseases. The oxidative potential (OP) of PM, displaying the ability of PM to oxidize the lung environment, is gaining strong interest in examining health risks associated with PM exposure. In this study, OP was measured by two different acellular assays (dithiothreitol, DTT, and ascorbic acid, AA) on PM10 filter samples from 15 yearly time series of filters collected at 14 different locations in France between 2013 and 2018, including urban, traffic and Alpine valley site typologies. A detailed chemical speciation was also performed on the same samples, allowing the source apportionment of PM using positive matrix factorization (PMF) for each series, for a total number of more than 1700 samples. This study then provides a large-scale synthesis of the source apportionment of OP using coupled PMF and multiple linear regression (MLR) models. The primary road traffic, biomass burning, dust, MSA-rich, and primary biogenic sources had distinct positive redox activity towards the OPDTT assay, whereas biomass burning and road traffic sources only display significant activity for the OPAA assay. The daily median source contribution to the total OPDTT highlighted the dominant influence of the primary road traffic source. Both the biomass burning and the road traffic sources contributed evenly to the observed OPAA. Therefore, it appears clear that residential wood burning and road traffic are the two main target sources to be prioritized in order to decrease significantly the OP in western Europe and, if the OP is a good proxy of human health impact, to lower the health risks from PM exposure.

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PM-induced oxidative potential: Two years measurements and source apportionment, on a seasonal basis, in Athens, Greece

10.5194/egusphere-egu21-15961 ◽

2021 ◽

Author(s):

Despina Paraskevopoulou ◽

George Grivas ◽

Aikaterini Bougiatioti ◽

Iasonas Stavroulas ◽

Maria Tsagkaraki ◽

...

Keyword(s):

Eastern Mediterranean ◽

Water Soluble ◽

Automated System ◽

Chemical Components ◽

Oxidative Potential ◽

Wood Burning ◽

Fine Aerosol ◽

Short Period ◽

Seasonal Basis

PM-induced oxidative stress has been proposed as a primary mechanism in cardiovascular and respiratory diseases, as well as premature death. Consequently, a variety of in vitro and in vivo assays have been developed in order to estimate the oxidative potential of ambient PM (Particulate matter), including the acellular assay of DTT (dithiothreitol), which is used in the present study. Athens, Greece is representative of air masses arriving over Eastern Mediterranean, highlighting the effect of long-range aerosol transportation and intense local emissions, such as wood burning for domestic heating purposes during the coldest period of the year.&#160;Most studies of aerosol oxidative potential (OP) cover a short period of time, while in this study the OP was measured during two years (2016-2018), in parallel with other PM chemical components, in order to identify the sources of aerosol OP. Fine aerosol fraction (PM2.5, diameter < 2.5 &#956;m) was collected, using quartz fibre filters and low-volume samplers, in the centre of Athens city.An innovative semi-automated system was used for the determination of PM water soluble oxidative potential, following the approach of Fang et al. (2015). Concurrent estimation of inorganic and organic aerosol components&#8217; concentrations was accomplished through Ion chromatography, Aerosol Chemical Speciation Monitor, Aethalometer and OC/EC analyser. Additionally, the samples were further analyzed by Inductively coupled plasma mass spectrometry for major and trace water-soluble metal concentrations. Principal component analysis and Positive Matrix Factorization are applied to identify the sources of fine aerosol at the studied site in Athens, and determine the contribution of each source to aerosol OP, on a seasonal basisAs expected, OP presented higher values during wintertime, when wood burning appeared to be the dominant source of aerosol. These results agree with previous studies, indicating that the combustion is the major source of water-soluble OP, both as primary and secondary emission (Paraskevopulou et al. 2019). Whereas during summer, the current study reveals, for the first time, the significant impact of water-soluble metals in aerosol toxicity during the warmest period of the year, over the studied area. The aforementioned combination of various PM chemical parameters leads to a scarce identification of various aerosol OP sources on a temporal basis, in the area of Eastern Mediterranean.

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Sensitive Measurement of Thrombopoietin by a Monoclonal Antibody Based Sandwich Enzyme-linked Immunosorbent Assay

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657725 ◽

1997 ◽

Vol 78 (04) ◽

pp. 1262-1267 ◽

Cited By ~ 46

Author(s):

Claudia C Folman ◽

Albert E G K von dem Borne ◽

Irma H J A M Rensink ◽

Winald Gerritsen ◽

C Ellen van der Schoot ◽

...

Keyword(s):

Monoclonal Antibody ◽

Monoclonal Antibodies ◽

Immunosorbent Assay ◽

Platelet Transfusion ◽

Large Scale ◽

Limit Of Detection ◽

Cross Reactivity ◽

Enzyme Linked Immunosorbent Assay ◽

Reliable Tool

SummaryIn this report a sensitive enzyme-linked immunosorbent assay (ELISA) for the measurement of plasma thrombopoietin (Tpo) is described that is solely based on monoclonal antibodies (MoAbs).The assay has an intra and inter-assay variance of 5-7% and 7-13%, respectively. Native and recombinant human Tpo (rhTpo) were recognized equally well, no cross reactivity with other cytokines was found and rhTpo added to plasma and serum was completely recovered. With the ELISA, Tpo concentrations in EDTA-anticoagulated plasma of all controls (n = 193) could be determined, since the limit of detection (2 ± 0.8 A.U./ml, mean ± sd) was lower than the concentration found in controls (11 ± 8 A.U./ml, mean ± sd; 2.5th-97.5th percentile: 4-32 A.U./ml). Tpo levels in serum were on average 3.4 times higher than in plasma.We showed in vivo that Tpo is bound by platelets, as in thrombocytopenic patients (n = 5) a platelet transfusion immediately led to a drop in plasma Tpo level, whereas in patients receiving chemotherapy the induced thrombocytopenia was followed by a rise in plasma Tpo levels.In summary, these results indicate that this ELISA is a reliable tool for Tpo measurements and is applicable for large scale studies.

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PM2.5 water-soluble elements in the southeastern United States: automated analytical method development, spatiotemporal distributions, source apportionment, and implications for heath studies

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-17189-2015 ◽

2015 ◽

Vol 15 (12) ◽

pp. 17189-17227 ◽

Cited By ~ 5

Author(s):

T. Fang ◽

H. Guo ◽

V. Verma ◽

R. E. Peltier ◽

R. J. Weber

Keyword(s):

Biomass Burning ◽

Method Development ◽

Mineral Dust ◽

Water Soluble ◽

Formation Factor ◽

Mobile Source ◽

Southeastern Us ◽

Redox Active ◽

Secondary Formation

Abstract. Water-soluble redox-active metals are potentially toxic due to the ability to catalytically generate reactive oxygen species (ROS) in vivo, leading to oxidative stress. As part of the Southeastern Center for Air Pollution and Epidemiology (SCAPE), we developed a method to quantify water-soluble elements, including redox-active metals, from a large number of filter samples (N = 530) in support of the Center's health studies. PM2.5 samples were collected during 2012–2013 at various sites (three urban, two rural, a near-road, and a road-side site) in the southeastern US, using high-volume samplers. Water-soluble elements (S, K, Ca, Ti, Mn, Fe, Cu, Zn, As, Se, Br, Sr, Ba, and Pb) were determined by extracting filters in deionized water and re-aerosolized for analyses by X-ray fluorescence (XRF) using an online aerosol element analyzer (Xact, Cooper Environmental). Concentrations ranged from detection limits (nominally 0.1 to 30 ng m−3) to 1.2 μg m−3, with S as the most abundant element, followed by Ca, K, Fe, Cu, Zn, and Ba. Positive Matrix Factorization (PMF) identified four factors that were associated with specific sources based on relative loadings of various tracers. These include: brake/tire wear (with tracers Ba and Cu); biomass burning (K); secondary formation (S, Se, and WSOC); and mineral dust (Ca). Of the four potentially toxic and relatively abundant metals (redox active Cu, Mn, Fe, and redox-inactive Zn), 51 % of Cu, 32 % of Fe, 17 % of Mn, and 45 % of Zn, were associated with the brake/tire factor. Mn was mostly associated with the mineral dust factor (45 %). These two factors were higher in warm (dryer) periods that favored particle re-suspension. Zn was found in a mixture of factors, with 26 % associated with mineral dust, 14 % biomass burning, and 13 % secondary formation. Roughly 50 % of Fe and 40 % of Cu was apportioned to the secondary formation factor, likely through increased solubility by sulfur-driven aerosol acidity. Linkages between sulfate and water-soluble Fe and Cu may account for some of the past observed associations between sulfate/sulfur oxide and health outcomes. For Cu, Mn, Fe, and Zn, only Fe was correlated with PM2.5 mass (r = 0.73–0.80). Overall, mobile source emissions generated through mechanical processes (re-entrained road dust, tire and break wear) and processing by secondary sulfate were major contributors to water-soluble metals known to be capable of generating ROS.

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An Automated one Stage Assay Technique for the Routine Evaluation of Factor VIII Concentrates

10.1055/s-0039-1682372 ◽

1977 ◽

Author(s):

M. Miller-Andersson ◽

M.J. Seghatchian ◽

T. Kirkwood ◽

I.M. Nilsson

Keyword(s):

Large Scale ◽

Assay System ◽

Automated System ◽

Collaborative Studies ◽

Factor Viii Concentrates ◽

Assay Methods ◽

The Given ◽

In Vivo Recovery ◽

Good Agreement

There is a general need for a reliable automated F VIII assay system with a large capacity for block bioassays. We present a method fulfilling these requirements. A rebuilt device for APTT determinations based on an optically clear activator and an artificial F VIII deficient substrate plasma has been used continously for 2 years. The substitution of hemophilia plasma by an artificial substrate plasma is a necessary feature for any satisfactory large scale automated system. There was no evidence of any differences between results obtained using this substrate and congenital deficient plasma. The reproducibility of the assay system was very good.(S.D. ≈ 10 %). And the results obtained by two different machines where indistingquish-able. The results showed very good agreement between the relative potency estimates of known F VIII standards obtained with this method and those found at recent international collaborative studies. However, comparison of assay results of clinical F VIII preparations with estimates of in vivo recovery shows that this method estimates lower potency of the given concentrates. These finding is in accordance with several other studies, that has shown that different assay methods detect relatively differing activities in preparations of different purity. Since it is important that the labeled unitage of the clinical material should continue to produce the same measured in vivo recovery at the “Reference Hemophilia Centre” (Malmö, Sweden), we have calculated simple convertion factors to apply to the assay results eliminating the appearent différencies.

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Source apportionment of atmospheric PM10 Oxidative Potential: synthesis of 15 year-round urban datasets in France

10.5194/acp-2021-77 ◽

2021 ◽

Author(s):

Samuël Weber ◽

Gaëlle Uzu ◽

Olivier Favez ◽

Lucille Joanna Borlaza ◽

Aude Calas ◽

...

Keyword(s):

Source Apportionment ◽

Health Risks ◽

Biomass Burning ◽

Large Scale ◽

Road Traffic ◽

Urban Traffic ◽

Redox Activity ◽

Significant Activity ◽

Oxidative Potential

Abstract. Reactive oxygen species (ROS) carried or induced by particulate matter (PM) are suspected to induce oxidative stress in vivo, leading to adverse health impacts, such as respiratory or cardiovascular diseases. The oxidative potential (OP) of PM, displaying the ability of PM to oxidize the lung environment, is gaining a strong interest to examine health risks associated to PM exposure. In this study, OP was measured by two different acellular assays (dithiothreitol, DTT and ascorbic acid, AA) on PM10 filter samples from 15 yearly time series of filters collected at 14 different locations in France between 2013 and 2018, including urban, traffic and Alpine valley site typologies. A detailed chemical speciation was also performed on the same samples allowing the source-apportionment of PM using positive matrix factorization (PMF) for each series, for a total number of more than 1700 samples. This study provides then a large-scale synthesis on the source-apportionment of OP using coupled PMF and multiple linear regression (MLR) models. The primary road traffic, biomass burning, dust, MSA-rich, and primary biogenic sources had distinct positive redox-activity towards the OPDTT assay, whereas biomass burning and road traffic sources only display significant activity for the OPAA assay. The daily median source contribution to the total OPDTT highlighted the dominant influence of the primary road traffic source. Both the biomass burning and the road traffic sources contributed evenly to the observed OPAA. Therefore, it appears clearly that residential wood burning and road traffic are the two main target sources to prioritized in order to decrease significantly the OP in Western Europe and, would the OP being a good proxy of human health impact, to lower the health risks from PM exposure.

Download Full-text

A semi-automated system for quantifying the oxidative potential of ambient particles in aqueous extracts using the dithiothreitol (DTT) assay: results from the Southeastern Center for Air Pollution and Epidemiology (SCAPE)