Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-24 (of 24 Records) |
Query Trace: Toth S[original query] |
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Characterizing spatiotemporal variation in transmission heterogeneity during the 2022 mpox outbreak in the USA (preprint)
Love J , LaPrete CR , Sheets TR , Vega Yon GG , Thomas A , Samore MH , Keegan LT , Adler FR , Slayton RB , Spicknall IH , Toth DJA . medRxiv 2023 14 Transmission heterogeneity plays a critical role in the dynamics of an epidemic. During an outbreak of an emerging infectious disease, efforts to characterize transmission heterogeneity are generally limited to quantifications during a small outbreak or a limited number of generations of a larger outbreak. Understanding how transmission heterogeneity itself varies over the course of a large enduring outbreak not only improves understanding of observed disease dynamics but also informs public health strategy and response. In this study, we employ a method, adaptable to other emerging infectious disease outbreaks, to quantify spatiotemporal variation in transmission heterogeneity for the 2022 mpox outbreak in the United States. Based on past research on mpox and following reports of potential superspreading events early in this outbreak, we expected to find high transmission heterogeneity as quantified by the dispersion parameter of the offspring distribution, k. Our methods use maximum likelihood estimation to fit a negative binomial distribution to transmission chain offspring distributions informed by a large mpox contact tracing dataset. We find that, while estimates of transmission heterogeneity varied across the outbreak with spatiotemporal pockets of higher heterogeneity, overall transmission heterogeneity was low. When testing our methods on simulated data from an outbreak with high transmission heterogeneity, k estimate accuracy depended on the contact tracing data completeness. Because the actual contact tracing data had high incompleteness, our values of k estimated from the empirical data may be artificially high. However, it is also possible that our estimates accurately reflect low transmission heterogeneity for the United States mpox outbreak. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license. |
Informatics modeling the relationship between proxy measures of respondent burden and survey response rates in a household panel survey
Earp M , Kaplan R , Toth D . J Off Stat 2022 38 (4) 1145-1175 Respondent burden has important implications for survey outcomes, including response rates and attrition in panel surveys. Despite this, respondent burden remains an understudied topic in the field of survey methodology, with few researchers systematically measuring objective and subjective burden factors in surveys used to produce official statistics. This research was designed to assess the impact of proxy measures of respondent burden, drawing on both objective (survey length and frequency), and subjective (effort, saliency, and sensitivity) burden measures on response rates over time in the Current Population Survey (CPS). Exploratory Factor Analysis confirmed the burden proxy measures were interrelated and formed five distinct factors. Regression tree models further indicated that both objective and subjective proxy burden factors were predictive of future CPS response rates. Additionally, respondent characteristics, including employment and marital status, interacted with these burden factors to further help predict response rates over time. We discuss the implications of these findings, including the importance of measuring both objective and subjective burden factors in production surveys. Our findings support a growing body of research suggesting that subjective burden and individual respondent characteristics should be incorporated into conceptual definitions of respondent burden and have implications for adaptive design. © 2022 Morgan Earp et al. |
Modeling the potential impact of administering vaccines against Clostridioides difficile infection to individuals in healthcare facilities.
Toth DJA , Keegan LT , Samore MH , Khader K , O'Hagan JJ , Yu H , Quintana A , Swerdlow DL . Vaccine 2020 38 (37) 5927-5932 BACKGROUND: A vaccine against Clostridioides difficile infection (CDI) is in development. While the vaccine has potential to both directly protect those vaccinated and mitigate transmission by reducing environmental contamination, the impact of the vaccine on C. difficile colonization remains unclear. Consequently, the transmission-reduction effect of the vaccine depends on the contribution of symptomatic CDI to overall transmission of C. difficile. METHODS: We designed a simulation model of CDI among patients in a network of 10 hospitals and nursing homes and calibrated the model using estimates of transmissibility from whole genome sequencing studies that estimated the fraction of CDI attributable to transmission from other CDI patients. We assumed the vaccine reduced the rate of progression to CDI among carriers by 25-95% after completion of a 3-dose vaccine course administered to randomly chosen patients at facility discharge. We simulated the administration of this vaccination campaign and tallied effects over 5 years. RESULTS: We estimated 30 times higher infectivity of CDI patients compared to other carriers. Simulations of the vaccination campaign produced an average reduction of 3-16 CDI cases per 1000 vaccinated patients, with 2-11 of those cases prevented among those vaccinated and 1-5 prevented among unvaccinated patients. CONCLUSIONS: Our findings demonstrate potential for a vaccine against CDI to reduce transmissions in healthcare facilities, even with no direct effect on carriage susceptibility. The vaccine's population impact will increase if received by individuals at risk for CDI onset in high-transmission settings. |
Composition-function analysis of HDL subpopulations: Influence of lipid composition on particle functionality
Niisuke K , Kuklenyik Z , Horvath KV , Gardner MS , Toth CA , Asztalos BF . J Lipid Res 2020 61 (3) 306-315 The composition-function relationship of HDL particles and its effects on the mechanisms driving coronary heart disease (CHD) is poorly understood. We tested the hypothesis that the functionality of HDL particles is significantly influenced by their lipid composition. Using a novel 3D-separation method, we isolated five different-sized HDL subpopulations from CHD patients who had low prebeta-1 functionality (ABCA1-dependent cholesterol-efflux normalized for prebeta-1 concentration) and controls who had either low or high prebeta-1 functionality. Molecular numbers of apoA-I, apoA-II, and eight major lipid classes were determined in each subpopulation by LC/MS. The average number of lipid molecules decreased from 422 in the large spherical alpha-1 particles to 57 in the small discoid prebeta-1 particles. With decreasing particle size, the relative concentration of free cholesterol (FC) decreased in alpha-mobility but not in prebeta-1 particles. Prebeta-1 particles contained more lipids than predicted; 30% of which were neutral lipids (cholesteryl ester and TG) indicating that these particles were mainly remodeled from larger particles not newly synthesized. There were significant correlations between HDL-particle functionality and the concentrations of several lipids. Unexpectedly, the phospholipid:FC ratio was significantly correlated with large-HDL-particle functionality but not with prebeta-1 functionality. There was significant positive correlation between particle functionality and total lipids in high-F controls indicating that the lipid-binding capacity of apoA-I plays a major role in the cholesterol efflux capacity of HDL particles. Functionality and lipid composition of HDL particles are significantly correlated and probably both are influenced by the lipid-binding capacity of apoA-I. |
FluChip-8G Insight: HA and NA subtyping of potentially pandemic influenza A viruses in a single assay.
Toth E , Dawson ED , Taylor AW , Stoughton RS , Blair RH , Johnson JEJr , Slinskey A , Fessler R , Smith CB , Talbot S , Rowlen K . Influenza Other Respir Viruses 2019 14 (1) 55-60 BACKGROUND: Global influenza surveillance in humans and animals is a critical component of pandemic preparedness. The FluChip-8G Insight assay was developed to subtype both seasonal and potentially pandemic influenza viruses in a single assay with a same day result. FluChip-8G Insight uses whole gene segment RT-PCR-based amplification to provide robustness against genetic drift and subsequent microarray detection with artificial neural network-based data interpretation. OBJECTIVES: The objective of this study was to verify and validate the performance of the FluChip-8G Insight assay for the detection and positive identification of human and animal origin non-seasonal influenza A specimens. METHODS: We evaluated the ability of the FluChip-8G Insight technology to type and HA and NA subtype a sample set consisting of 297 results from 180 unique non-seasonal influenza A strains (49 unique subtypes). RESULTS: FluChip-8G Insight demonstrated a positive percent agreement >/=93% for 5 targeted HA and 5 targeted NA subtypes except for H9 (88%), and negative percent agreement exceeding 95% for all targeted subtypes. CONCLUSIONS: The FluChip-8G Insight neural network-based algorithm used for virus identification performed well over a data set of 297 naive sample results, and can be easily updated to improve performance on emerging strains without changing the underlying assay chemistry. |
Clinical validation of the FluChip-8G Influenza A+B Assay for influenza type and subtype identification
Blair RH , Dawson ED , Taylor AW , Johnson JEJr , Slinskey AH , O'Neil K , Smolak AW , Toth E , Liikanen K , Stoughton RS , Smith CB , Talbot S , Rowlen KL . J Clin Virol 2019 118 20-27 BACKGROUND: The FluChip-8G Influenza A+B Assay is a multiplexed influenza RT-PCR and microarray-based assay with same day turnaround time, developed to subtype seasonal A viruses (H1N1pdm2009 and H3N2), distinguish B viruses as Yamagata or Victoria lineage, and is the only FDA cleared assay capable of positive identification of a wide variety of A subtypes as "non-seasonal" A viruses from human nasal specimens. OBJECTIVE: To evaluate clinical performance of the FluChip-8G Influenza A+B Assay for detection of seasonal influenza viruses in nasal and nasopharyngeal swab specimens, and to evaluate performance for detection of non-seasonal influenza viruses using contrived samples. STUDY DESIGN: For seasonal viruses, a multisite study of the FluChip-8G Influenza A+B Assay using prospectively and retrospectively collected nasal and nasopharyngeal swabs was performed using the FDA-cleared CDC Human Flu Dx Panel as the comparator assay. For non-seasonal viruses, testing was performed at a single site using contrived samples from 100 unique non-seasonal strains representing 41 subtypes. RESULTS: Sensitivity (95% CI) and specificity (95% CI) for each target group, respectively, from results of 1689 clinical specimens were: seasonal H1N1pdm2009: 96.4% (87.9-99.0), 99.3% (98.8-99.6), seasonal H3N2: 91.8% (87.7-94.7), 99.7% (99.2-99.9), Influenza B Victoria: 100% (94.0-100.0), 99.9% (99.6-100.0), and Influenza B Yamagata: 95.6% (89.2-98.3), 99.9% (99.6-100.0). The sensitivity and specificity from contrived influenza A non-seasonal viruses was determined to be 99.0% (94.6-99.8) and 100% (96.7-100.0). CONCLUSION: The FluChip-8G Influenza A+B Assay has robust sensitivity and specificity for detecting and identifying all target virus groups, including non-seasonal influenza A, with same day results. |
Analytical Evaluation of the Microarray-Based FluChip-8G Influenza A+B Assay.
Taylor AW , Dawson ED , Blair RH , Johnson JEJr , Slinskey AH , Smolak AW , Toth E , Liikanen K , Stoughton RS , Smith C , Talbot S , Rowlen KL . J Virol Methods 2019 273 113686 BACKGROUND: Influenza causes a significant annual disease burden, with characterization of the infecting virus important in clinical and public health settings. Rapid immunoassays are fast but insensitive, whereas real-time RT-PCR is sensitive but susceptible to genetic mutations and often requires multiple serial assays. The FluChip-8 G Influenza A + B Assay provides type and subtype/lineage identification of influenza A and B, including non-seasonal A viruses, in a single microarray-based assay with same day turnaround time. OBJECTIVE: To evaluate key analytical performance characteristics of the FluChip-8 G Influenza A + B Assay. STUDY DESIGN: Analytical sensitivity, cross-reactivity, and multi-site reproducibility were evaluated. RESULTS: The limit of detection (LOD) for the FluChip-8 G influenza A + B Assay ranged from 5.8 x 10(2) - 1.5 x 10(5) genome copies/mL, with most samples 2 x 10(3) genome copies/mL ( 160 genome copies/reaction). Fifty two (52) additional strains were correctly identified near the LOD, demonstrating robust reactivity. Two variant viruses (H1N1v and H3N2v) resulted in dual identification as both "non-seasonal influenza A" and A/H1N1 pdm 2009. No reproducible cross-reactivity was observed for the 34 organisms tested, however, challenges with internal control inhibition due to crude growth matrix were observed. Lastly, samples tested near the LOD showed high reproducibility (97.0% (95% CI 94.7 - 98.7)) regardless of operator, site, reagent lot, or testing day. CONCLUSION: The FluChip-8 G Influenza A + B Assay is an effective new method for detecting and identifying both seasonal and non-seasonal influenza viruses, as revealed by good sensitivity and robust reactivity to 52 unique strains of influenza virus. In addition, the lack of cross-reactivity to non-influenza pathogens and high lab-to-lab reproducibility highlight the analytical performance of the assay as an alternative to real-time RT-PCR and sequencing-based assays. Clinical validation of the technology in a multi-site clinical study is the subject of a separate investigation. |
Nuts and bolts of protein quantification by online trypsin digestion coupled LC-MS/MS analysis
Toth CA , Kuklenyik Z , Barr JR . Methods Mol Biol 2019 1871 295-311 Protein digestion coupled to liquid chromatography and tandem mass spectrometry (LC-MS/MS) detection enables multiplexed quantification of proteins in complex biological matrices. However, the reproducibility of enzymatic digestion of proteins to produce proteotypic target peptides is a major limiting factor of assay precision. Online digestion using immobilized trypsin addresses this problem through precise control of digestion conditions and time. Because online digestion is typically for a short time, the potential for peptide degradation, a major source of measurement bias, is significantly reduced. Online proteolysis requires minimal sample preparation and is easily coupled to LC-MS/MS systems, further reducing potential method variability. We describe herein a method optimized for the multiplexed quantification of several apolipoproteins in human serum using on-column digestion. We highlight key features of the method that enhance assay accuracy and precision. These include the use of value-assigned serum as calibrators and stable isotope-labeled (SIL) peptide analogs as internal standards. We also comment on practical aspects of column switching valve design, instrument maintenance, tandem mass spectrometry data acquisition, and data processing. |
The Environment and Reproductive Health (EARTH) Study: A prospective preconception cohort
Messerlian C , Williams PL , Ford JB , Chavarro JE , Minguez-Alarcon L , Dadd R , Braun JM , Gaskins AJ , Meeker JD , James-Todd T , Chiu YH , Nassan FL , Souter I , Petrozza J , Keller M , Toth TL , Calafat AM , Hauser R . Hum Reprod Open 2018 2018 (2) Background: The Environment and Reproductive Health (EARTH) Study is an ongoing prospective preconception cohort designed to investigate the impact of environmental, nutritional, and lifestyle factors among both women and men on fertility and pregnancy outcomes. Methods: The EARTH Study recruits women 18 to 45 years and men 18 to 55 years seeking fertility evaluation and treatment at the Massachusetts General Hospital (MGH) Fertility Center, Boston, USA. Women and men are eligible to join either independently or as a couple. Participants are followed from study entry throughout each fertility treatment cycle, once per trimester of pregnancy (for those achieving pregnancy), and up to labor and delivery, or until they discontinue treatment or withdraw from the study. The study collects biological samples, self-reported questionnaire data (including a food frequency questionnaire) and clinically abstracted information. Results: As of June 2017, the study cohort included 799 women and 487 men (447 couples; 40 men joined without female partners). Women were on average 34.7 years old at time of enrolment and predominantly Caucasian (81%), educated (49% have a graduate degree), and nulliparous (83%). Men were on average 36.6 years at baseline and mostly Caucasian (86%) and never-smokers (67%). Conclusions: The EARTH Study is one of the few cohorts designed to examine multiple potentially critical windows of vulnerability, including the paternal and maternal preconception windows and the periconception and prenatal windows in pregnancy. It is also one of the few human studies that has assessed potential interactions between environmental exposures and dietary factors. |
Core lipid, surface lipid and apolipoprotein composition analysis of lipoprotein particles as a function of particle size in one workflow integrating asymmetric flow field-flow fractionation and liquid chromatography-tandem mass spectrometry
Kuklenyik Z , Jones JI , Gardner MS , Schieltz DM , Parks BA , Toth CA , Rees JC , Andrews ML , Carter K , Lehtikoski AK , McWilliams LG , Williamson YM , Bierbaum KP , Pirkle JL , Barr JR . PLoS One 2018 13 (4) e0194797 Lipoproteins are complex molecular assemblies that are key participants in the intricate cascade of extracellular lipid metabolism with important consequences in the formation of atherosclerotic lesions and the development of cardiovascular disease. Multiplexed mass spectrometry (MS) techniques have substantially improved the ability to characterize the composition of lipoproteins. However, these advanced MS techniques are limited by traditional pre-analytical fractionation techniques that compromise the structural integrity of lipoprotein particles during separation from serum or plasma. In this work, we applied a highly effective and gentle hydrodynamic size based fractionation technique, asymmetric flow field-flow fractionation (AF4), and integrated it into a comprehensive tandem mass spectrometry based workflow that was used for the measurement of apolipoproteins (apos A-I, A-II, A-IV, B, C-I, C-II, C-III and E), free cholesterol (FC), cholesterol esters (CE), triglycerides (TG), and phospholipids (PL) (phosphatidylcholine (PC), sphingomyelin (SM), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and lysophosphatidylcholine (LPC)). Hydrodynamic size in each of 40 size fractions separated by AF4 was measured by dynamic light scattering. Measuring all major lipids and apolipoproteins in each size fraction and in the whole serum, using total of 0.1 ml, allowed the volumetric calculation of lipoprotein particle numbers and expression of composition in molar analyte per particle number ratios. Measurements in 110 serum samples showed substantive differences between size fractions of HDL and LDL. Lipoprotein composition within size fractions was expressed in molar ratios of analytes (A-I/A-II, C-II/C-I, C-II/C-III. E/C-III, FC/PL, SM/PL, PE/PL, and PI/PL), showing differences in sample categories with combinations of normal and high levels of Total-C and/or Total-TG. The agreement with previous studies indirectly validates the AF4-LC-MS/MS approach and demonstrates the potential of this workflow for characterization of lipoprotein composition in clinical studies using small volumes of archived frozen samples. |
Ultraperformance liquid chromatography tandem mass spectrometry method to determine formaldehyde hemoglobin adducts in humans as biomarker for formaldehyde exposure
Yang M , Ospina M , Tse C , Toth S , Caudill SP , Vesper HW . Chem Res Toxicol 2017 30 (8) 1592-1598 Formaldehyde (FA) is an environmental chemical classified as a human carcinogen. It is highly reactive and can bind covalently with hemoglobin (Hb) to produce Hb adducts. Measurement of these Hb adducts provides valuable information about exposure to this chemical. We developed a robust, ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantifying FA-Hb adducts in red blood cells. The method measures the FA-VHLTPEEK peptide after trypic digestion. The peptide is a FA adduct at the N-terminus of the beta chain of human Hb. Method mean (+/-SD) accuracy, determined by recovery in quality control and blank material was 103.2% +/- 8.11. The mean among-day and within-day coefficients of variation determined at three concentration levels (%CV) were 9.2% (range: 7.2-10.2%) and 4.9% (range 3.1-7.3%), respectively. The limit of detection was 3.4 nmol/g Hb. This method was applied to the analysis of 135 human blood samples, and FA-VHLTPEEK was detected in all study samples. FA-VHLTPEEK concentrations were not significantly different between smokers and nonsmokers. This work is the first validated UPLC-MS/MS method in which a FA peptide derived from a FA-Hb adduct could be used to monitor exposure to FA in population studies. |
The potential for interventions in a long-term acute care hospital to reduce transmission of carbapenem-resistant Enterobacteriaceae in affiliated healthcare facilities
Toth DJA , Khader K , Slayton RB , Kallen AJ , Gundlapalli AV , O'Hagan JJ , Fiore AE , Rubin MA , Jernigan JA , Samore MH . Clin Infect Dis 2017 65 (4) 581-587 Background.: Carbapenem-resistant Enterobacteriaceae (CRE) are high-priority bacterial pathogens targeted for efforts to decrease transmissions and infections in healthcare facilities. Some regions have experienced CRE outbreaks that were likely amplified by frequent transmission in long-term acute care hospitals (LTACHs). Planning and funding intervention efforts focused on LTACHs is one proposed strategy to contain outbreaks; however, the potential regional benefits of such efforts are unclear. Methods.: We designed an agent-based simulation model of patients in a regional network of 10 healthcare facilities including 1 LTACH, 3 short-stay acute care hospitals (ACHs) and 6 nursing homes (NHs). The model was calibrated to achieve realistic patient flow and CRE transmission and detection rates. We then simulated the initiation of an entirely LTACH-focused intervention in a previously CRE-free region, including active surveillance for CRE carriers and enhanced isolation of identified carriers. Results.: When initiating the intervention at the 1st clinical CRE detection in the LTACH, cumulative CRE transmissions over 5 years across all 10 facilities were reduced by 79-93% compared to no-intervention simulations. This result was robust to changing assumptions for transmission within non-LTACH facilities and flow of patients from the LTACH. Delaying the intervention until the 20th CRE detection resulted in substantial delays in achieving optimal regional prevalence, while still reducing transmissions by 60-79% over 5 years. Conclusions.: Focusing intervention efforts on LTACHs is potentially a highly efficient strategy for reducing CRE transmissions across an entire region, particularly when implemented as early as possible in an emerging outbreak. |
Paternal and maternal urinary phthalate metabolite concentrations and birth weight of singletons conceived by subfertile couples
Messerlian C , Braun JM , Minguez-Alarcon L , Williams PL , Ford JB , Mustieles V , Calafat AM , Souter I , Toth T , Hauser R . Environ Int 2017 107 55-64 BACKGROUND: Prenatal phthalate exposure has been inconsistently associated with fetal growth and infant birth weight. However, the effect of exposure during the paternal and maternal preconception period remains understudied. OBJECTIVES: To investigate associations of paternal and maternal preconception and maternal prenatal urinary phthalate metabolite concentrations with birth weight. METHODS: The study comprised 364 singletons born to 364 mothers and 195 fathers (195 couples) from the EARTH Study, a prospective cohort of couples from Boston, MA. Births were categorized by mode of conception: in-vitro fertilization based (IVF) (n=208) or non-IVF based (n=156, intrauterine insemination or non-medically assisted/natural conception). We measured urinary concentrations of eleven phthalate metabolites in maternal (n=1425) and paternal (n=489) preconception and maternal prenatal (n=781) samples. Birth weight was abstracted from delivery records. Covariate-adjusted associations between loge-phthalate metabolite concentrations and birth weight were evaluated separately by mode of conception using multivariable linear regression. RESULTS: Each loge-unit increase in paternal urinary concentration of the sum of di(2-ethylhexyl) phthalate (SigmaDEHP) metabolites was associated with a 90 gram (95% CI: -165, -15) decrease in birth weight among IVF singletons, but not among non-IVF singletons (18g; 95% CI: -76, 113). Additional adjustment for maternal prenatal SigmaDEHP concentrations modestly strengthened findings among IVF singletons. While few associations were found with maternal preconception phthalate metabolites, we observed an inverse relationship between several maternal prenatal urinary phthalate metabolite concentrations and birth weight among IVF singletons in covariate-adjusted models. However, with further adjustment for specific paternal phthalate metabolite concentrations, these associations were attenuated and no longer significant. CONCLUSIONS: Paternal preconception urinary concentration of SigmaDEHP metabolites was associated with a decrease in birth weight among IVF-conceived singletons. These results, if replicated, highlight the importance of preconception health, especially among subfertile couples. |
Optimization of the linear quantification range of an online trypsin digestion coupled liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform
Kuklenyik Z , Jones JI , Toth CA , Gardner MS , Pirkle JL , Barr JR . Instrum Sci Technol 2017 46 (1) 102-114 Tandem mass spectrometry (MS/MS)-based proteomic workflows with a bottom-up approach require enzymatic digestion of proteins to peptide analytes, usually by trypsin. Online coupling of trypsin digestion of proteins, using an immobilized enzyme reactor (IMER), with liquid chromatography (LC) and MS/MS is becoming a frequently used approach. However, finding IMER digestion conditions that allow quantitative analysis of multiple proteins with wide range of endogenous concentration requires optimization of multiple interactive parameters: digestion buffer flow rate, injection volume, sample dilution, and surfactant type/concentration. In this report, we present a design of experiment approach for the optimization of an integrated IMER-LC-MS/MS platform. With bovine serum albumin as a model protein, the digestion efficacy and digestion rate were monitored based on LC-MS/MS peak area count versus protein concentration regression. The optimal parameters were determined through multivariate surface response modeling and consideration of diffusion controlled immobilized enzyme kinetics. The results may provide guidance to other users for the development of quantitative IMER-LC-MS/MS methods for other proteins. |
High throughput quantification of apolipoproteins A-I and B-100 by isotope dilution mass spectrometry targeting fast trypsin releasable peptides without reduction and alkylation
Parks BA , Schieltz DM , Andrews ML , Gardner MS , Rees JC , Toth CA , Jones JI , McWilliams LG , Kuklenyik Z , Pirkle JL , Barr JR . Proteomics Clin Appl 2017 11 PURPOSE: Apolipoprotein A-I (ApoA-I) and Apolipoprotein B-100 (ApoB-100) are amphipathic proteins that are strong predictors of cardiovascular disease risk. The traceable calibration of apolipoprotein assays is a persistent challenge, especially for ApoB-100, which cannot be solubilized in purified form. EXPERIMENTAL DESIGN: Simultaneous quantitation method for ApoA-I and ApoB-100 was developed using tryptic digestion without pre-digestion reduction and alkylation, followed by liquid chromatography separation coupled with isotope dilution mass spectrometry (IDMS) analysis. The accuracy of the method was assured by selecting structurally exposed signature peptides, optimal choice of detergent, protein:enzyme ratio, and incubation time. Peptide calibrators were value assigned by isobaric-tagging-IDMS amino acid analysis. RESULTS: The method reproducibility was validated in technical repeats of three serum samples, giving 2-3% intra-day CVs (N = 5) and <7% inter-day CVs (N = 21). The repeated analysis of inter-laboratory harmonization standards showed -1% difference for ApoA-I and -12% for ApoB-100 relative to the assigned value. The applicability of the method was demonstrated by repeated analysis of 24 patient samples with a wide range of total cholesterol and triglyceride levels. CONCLUSIONS AND CLINICAL RELEVANCE: The method is applicable for simultaneous analysis of ApoA-I and ApoB-100 in patient samples, and for characterization of serum pool calibrators for other analytical platforms. |
On-column trypsin digestion coupled with LC-MS/MS for quantification of apolipoproteins
Toth CA , Kuklenyik Z , Jones JI , Parks BA , Gardner MS , Schieltz DM , Rees JC , Andrews ML , McWilliams LG , Pirkle JL , Barr JR . J Proteomics 2016 150 258-267 Apolipoproteins measured in plasma or serum are potential biomarkers for assessing metabolic irregularities that are associated with the development of cardiovascular disease (CVD). LC-MS/MS allows quantitative measurement of multiple apolipoproteins in the same sample run.However, the accuracy and precision of the LC-MS/MS measurement depends on the reproducibility of the enzymatic protein digestion step. With the application of an immobilized enzyme reactor (IMER), the reproducibility of the trypsin digestion can be controlled with high precision via flow rate, column volume and temperature. In this report, we demonstrate the application of an integrated IMER-LC-MS/MS platform for the simultaneous quantitative analysis of eight apolipoproteins. Using a dilution series of a characterized serum pool as calibrator, the method was validated by repeated analysis of pooled sera and individual serum samples with a wide range of lipid profiles, all showing intra-assay CV<4.4% and inter-assay CV<8%. In addition, the method was compared with traditional homogeneous digestion coupled LC-MS/MS for the quantification of apoA-I and apoB-100. Applied in large scale human population studies, this method can serve the translation of a wider panel of apolipoprotein biomarkers from research to clinical application. SIGNIFICANCE: Currently, the translation of apolipoprotein biomarkers to clinical application is impaired because of the high cost of large cohort studies using traditional single-analyte immunoassays. The application of on-line tryptic digestion coupled with LC-MS/MS analysis is an effective way to address this problem. In this work we demonstrate a high throughput, multiplexed, automated proteomics workflow for the simultaneous analysis of multiple proteins. |
Estimates of social contact in a middle school based on self-report and wireless sensor data
Leecaster M , Toth DJ , Pettey WB , Rainey JJ , Gao H , Uzicanin A , Samore M . PLoS One 2016 11 (4) e0153690 Estimates of contact among children, used for infectious disease transmission models and understanding social patterns, historically rely on self-report logs. Recently, wireless sensor technology has enabled objective measurement of proximal contact and comparison of data from the two methods. These are mostly small-scale studies, and knowledge gaps remain in understanding contact and mixing patterns and also in the advantages and disadvantages of data collection methods. We collected contact data from a middle school, with 7th and 8th grades, for one day using self-report contact logs and wireless sensors. The data were linked for students with unique initials, gender, and grade within the school. This paper presents the results of a comparison of two approaches to characterize school contact networks, wireless proximity sensors and self-report logs. Accounting for incomplete capture and lack of participation, we estimate that "sensor-detectable", proximal contacts longer than 20 seconds during lunch and class-time occurred at 2 fold higher frequency than "self-reportable" talk/touch contacts. Overall, 55% of estimated talk-touch contacts were also sensor-detectable whereas only 15% of estimated sensor-detectable contacts were also talk-touch. Contacts detected by sensors and also in self-report logs had longer mean duration than contacts detected only by sensors (6.3 vs 2.4 minutes). During both lunch and class-time, sensor-detectable contacts demonstrated substantially less gender and grade assortativity than talk-touch contacts. Hallway contacts, which were ascertainable only by proximity sensors, were characterized by extremely high degree and short duration. We conclude that the use of wireless sensors and self-report logs provide complementary insight on in-school mixing patterns and contact frequency. |
The effects of apolipoprotein B depletion on HDL subspecies composition and function
Davidson WS , Heink A , Sexmith H , Melchior JT , Gordon SM , Kuklenyik Z , Woolett L , Barr JR , Jones JI , Toth CA , Shah AS . J Lipid Res 2016 57 (4) 674-86 High density lipoprotein (HDL) cholesterol efflux function may be a more robust biomarker of coronary artery disease risk than HDL cholesterol (HDL-C). To study HDL function, apoB containing lipoproteins are precipitated from serum. Whether apoB precipitation affects HDL subspecies composition and function has not been thoroughly investigated. We studied the effects of four common apoB precipitation methods (polyethylene glycol (PEG), dextran sulfate/MgCl2, heparin sodium/MnCl2 and LipoSep immunoprecipitant (IP)) on HDL subspecies composition, apolipoproteins and function (cholesterol efflux and reduction of LDL oxidation). PEG dramatically shifted the size distribution of HDL and apolipoproteins (assessed by two independent methods), while leaving substantial amounts of reagent in the sample. PEG also changed the distribution of cholesterol efflux and LDL oxidation across size fractions, but not overall efflux across the HDL range. Dextran sulfate/MgCl2 and heparin sodium/MnCl2 did not change the size distribution of HDL subspecies but altered the quantity of a subset of apolipoproteins. LipoSep IP resulted in a shift in the HDL size distribution, but less so than PEG. Thus, each of the apoB precipitation methods affected HDL composition and/or size distribution. We conclude that careful evaluation is needed when selecting apoB depletion methods for existing and future bioassays of HDL function. |
Urinary paraben concentrations and in vitro fertilization outcomes among women from a fertility clinic
Minguez-Alarcon L , Chiu YH , Messerlian C , Williams PL , Sabatini ME , Toth TL , Ford JB , Calafat AM , Hauser R . Fertil Steril 2015 105 (3) 714-721 OBJECTIVE: To explore the relationship between urinary paraben concentrations and IVF outcomes among women attending an academic fertility center. DESIGN: Prospective cohort study. SETTING: Fertility clinic in a hospital setting. PATIENT(S): A total of 245 women contributing 356 IVF cycles. INTERVENTION(S): None. Quantification of urinary concentrations of parabens by isotope-dilution tandem mass spectrometry, and assessment of clinical endpoints of IVF treatments abstracted from electronic medical records at the academic fertility center. MAIN OUTCOME MEASURE(S): Total and mature oocyte counts, proportion of high-quality embryos, fertilization rates, and rates of implantation, clinical pregnancy, and live births. RESULT(S): The geometric means of the urinary concentrations of methylparaben, propylparaben, and butylparaben in our study population were 133, 24, and 1.5 mug/L, respectively. In models adjusted for age, body mass index, race/ethnicity, smoking status, and primary infertility diagnosis, urinary methylparaben, propylparaben, and butylparaben concentrations were not associated with IVF outcomes, specifically total and mature oocyte counts, proportion of high embryo quality, and fertilization rates. Moreover, no significant associations were found between urinary paraben concentrations and rates of implantation, clinical pregnancy, and live births. CONCLUSION(S): Urinary paraben concentrations were not associated with IVF outcomes among women undergoing infertility treatments. |
Vital Signs: estimated effects of a coordinated approach for action to reduce antibiotic-resistant infections in health care facilities - United States
Slayton RB , Toth D , Lee BY , Tanner W , Bartsch SM , Khader K , Wong K , Brown K , McKinnell JA , Ray W , Miller LG , Rubin M , Kim DS , Adler F , Cao C , Avery L , Stone NT , Kallen A , Samore M , Huang SS , Fridkin S , Jernigan JA . MMWR Morb Mortal Wkly Rep 2015 64 (30) 826-31 BACKGROUND: Treatments for health care-associated infections (HAIs) caused by antibiotic-resistant bacteria and Clostridium difficile are limited, and some patients have developed untreatable infections. Evidence-supported interventions are available, but coordinated approaches to interrupt the spread of HAIs could have a greater impact on reversing the increasing incidence of these infections than independent facility-based program efforts. METHODS: Data from CDC's National Healthcare Safety Network and Emerging Infections Program were analyzed to project the number of health care-associated infections from antibiotic-resistant bacteria or C. difficile both with and without a large scale national intervention that would include interrupting transmission and improved antibiotic stewardship. As an example, the impact of reducing transmission of one antibiotic-resistant infection (carbapenem-resistant Enterobacteriaceae [CRE]) on cumulative prevalence and number of HAI transmission events within interconnected groups of health care facilities was modeled using two distinct approaches, a large scale and a smaller scale health care network. RESULTS: Immediate nationwide infection control and antibiotic stewardship interventions, over 5 years, could avert an estimated 619,000 HAIs resulting from CRE, multidrug-resistant Pseudomonas aeruginosa, invasive methicillin-resistant Staphylococcus aureus (MRSA), or C. difficile. Compared with independent efforts, a coordinated response to prevent CRE spread across a group of inter-connected health care facilities resulted in a cumulative 74% reduction in acquisitions over 5 years in a 10-facility network model, and 55% reduction over 15 years in a 102-facility network model. CONCLUSIONS: With effective action now, more than half a million antibiotic-resistant health care-associated infections could be prevented over 5 years. Models representing both large and small groups of interconnected health care facilities illustrate that a coordinated approach to interrupting transmission is more effective than historical independent facilitybased efforts. IMPLICATIONS FOR PUBLIC HEALTH: Public health-led coordinated prevention approaches have the potential to more completely address the emergence and dissemination of these antibiotic-resistant organisms and C. difficile than independent facility-based efforts. |
The role of heterogeneity in contact timing and duration in network models of influenza spread in schools
Toth DJ , Leecaster M , Pettey WB , Gundlapalli AV , Gao H , Rainey JJ , Uzicanin A , Samore MH . J R Soc Interface 2015 12 (108) 20150279 Influenza poses a significant health threat to children, and schools may play a critical role in community outbreaks. Mathematical outbreak models require assumptions about contact rates and patterns among students, but the level of temporal granularity required to produce reliable results is unclear. We collected objective contact data from students aged 5-14 at an elementary school and middle school in the state of Utah, USA, and paired those data with a novel, data-based model of influenza transmission in schools. Our simulations produced within-school transmission averages consistent with published estimates. We compared simulated outbreaks over the full resolution dynamic network with simulations on networks with averaged representations of contact timing and duration. For both schools, averaging the timing of contacts over one or two school days caused average outbreak sizes to increase by 1-8%. Averaging both contact timing and pairwise contact durations caused average outbreak sizes to increase by 10% at the middle school and 72% at the elementary school. Averaging contact durations separately across within-class and between-class contacts reduced the increase for the elementary school to 5%. Thus, the effect of ignoring details about contact timing and duration in school contact networks on outbreak size modelling can vary across different schools. |
Liposome-antigen-nucleic acid complexes protect mice from lethal challenge with western and eastern equine encephalitis viruses
Phillips AT , Schountz T , Toth AM , Rico AB , Jarvis DL , Powers AM , Olson KE . J Virol 2014 88 (3) 1771-80 Alphaviruses are mosquito-borne viruses that cause significant disease in animals and humans. Western equine encephalitis virus (WEEV) and eastern equine encephalitis virus (EEEV), two New World alphaviruses, can cause fatal encephalitis, and EEEV is a select agent of concern in biodefense. However, we have no antiviral therapies against alphaviral disease, and current vaccine strategies target only a single alphavirus species. In an effort to develop new tools for a broader response to outbreaks, we designed and tested a novel alphavirus vaccine comprised of cationic lipid nucleic acid complexes (CLNCs) and the ectodomain of WEEV E1 protein (E1ecto). Interestingly, we found that the CLNC component, alone, had therapeutic efficacy, as it increased survival of CD-1 mice following lethal WEEV infection. Immunization with the CLNC-WEEV E1ecto mixture (lipid-antigen-nucleic acid complexes [LANACs]) using a prime-boost regimen provided 100% protection in mice challenged with WEEV subcutaneously, intranasally, or via mosquito. Mice immunized with LANACs mounted a strong humoral immune response but did not produce neutralizing antibodies. Passive transfer of serum from LANAC E1ecto-immunized mice to nonimmune CD-1 mice conferred protection against WEEV challenge, indicating that antibody is sufficient for protection. In addition, the LANAC E1ecto immunization protocol significantly increased survival of mice following intranasal or subcutaneous challenge with EEEV. In summary, our LANAC formulation has therapeutic potential and is an effective vaccine strategy that offers protection against two distinct species of alphavirus irrespective of the route of infection. We discuss plausible mechanisms as well the potential utility of our LANAC formulation as a pan-alphavirus vaccine. |
Bioluminescent imaging and histopathologic characterization of WEEV neuroinvasion in outbred CD-1 mice
Phillips AT , Stauft CB , Aboellail TA , Toth AM , Jarvis DL , Powers AM , Olson KE . PLoS One 2013 8 (1) e53462 Western equine encephalitis virus (WEEV; Alphavirus) is a mosquito-borne virus that can cause severe encephalitis in humans and equids. Previous studies have shown that intranasal infection of outbred CD-1 mice with the WEEV McMillan (McM) strain result in high mortality within 4 days of infection. Here in vivo and ex vivo bioluminescence (BLM) imaging was applied on mice intranasally infected with a recombinant McM virus expressing firefly luciferase (FLUC) to track viral neuroinvasion by FLUC detection and determine any correlation between BLM and viral titer. Immunological markers of disease (MCP-1 and IP-10) were measured and compared to wild type virus infection. Histopathology was guided by corresponding BLM images, and showed that neuroinvasion occurred primarily through cranial nerves, mainly in the olfactory tract. Olfactory bulb neurons were initially infected with subsequent spread of the infection into different regions of the brain. WEEV distribution was confirmed by immunohistochemistry as having marked neuronal infection but very few infected glial cells. Axons displayed infection patterns consistent with viral dissemination along the neuronal axis. The trigeminal nerve served as an additional route of neuroinvasion showing significant FLUC expression within the brainstem. The recombinant virus WEEV.McM.FLUC had attenuated replication kinetics and induced a weaker immunological response than WEEV.McM but produced comparable pathologies. Immunohistochemistry staining for FLUC and WEEV antigen showed that transgene expression was present in all areas of the CNS where virus was observed. BLM provides a quantifiable measure of alphaviral neural disease progression and a method for evaluating antiviral strategies. |
[Post vaccination rotavirus surveillance in Hungary, in 2007]
Laszlo B , Czellar E , Deak J , Juhasz A , Kovacs J , Konya J , Meszaros J , Meszner Z , Mihaly I , Molnar P , Nyul Z , Patri L , Puskas E , Schneider F , Siffel C , Toth A , Toth E , Szucs G , Banyai K . Orv Hetil 2009 150 (31) 1443-50 Vaccination is the main strategy to control severe dehydrating gastroenteritis caused by rotaviruses in early childhood. The availability of new generation rotavirus vaccines has led to an intensification of strain surveillance worldwide, in part, to gauge the impact of the possible vaccine-driven immune selection of wild-type rotavirus strains. In the present study, authors describe the strain prevalence data obtained in 2007, with the involvement of different regions of Hungary. Genomic RNA was extracted from rotavirus-positive stool samples collected mainly from children and then subjected to genotyping using multiplex RT-PCR assay. Type-specific primers targeted G1 to G4, G6, G8 to G10, and G12 VP7 specificities, and P[4], P[6], and P[8] to P[11] VP4 specificities were used. Out of 489 rotavirus-positive specimens, collected from 482 patients, 466 and 474 were successfully G and P typed, respectively, and both G and P type specificities could be assigned for 457 strains. Prevalence data showed the predominance of G4P[8] (31.5%) strains, followed by G1P[8] (28.3%), G2P[4] (19.3%), and G9P[8] (10.2%). Minority strains were G1P[4] (0.4%), G2P[8] (1.3%), G3P[9] (0.2%), G4P[6] (0.7%), G6P[9] (0.4%), G8P[8] (0.2%), G9P[4] (0.2%), G9P[6] (0.8%), and G12P[8] (0.4%). Mixed infections were found in 1.2% of the samples, while 4.9% remained partially or fully non-typified. Our data indicate that the antigen specificities of medically important rotavirus strains identified in this 1-year study are well represented in the vaccines available in the pharmaceutical private market in Hungary. Depending on the vaccination coverage achievable in the forthcoming years, the post-vaccination rotavirus strain surveillance may allow us to gain comprehensive information on the impact of rotavirus vaccines on the prevalence of circulating rotavirus strains. |
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