Variability of Urinary Concentrations of Phenols, Parabens, and Triclocarban during Pregnancy in First Morning Voids and Pooled Samples

ABSTRACT Microchemical determinations of glycosaminoglycans and collagen were preformed in isolated histological zones from sections of tibial epiphyseal plate biopsies obtained from children with growth disorders (pituitary dwarfism, congenital myxoedema, Turner's syndrome, Noonan's syndrome, mucopolysaccharidosis type VI, vitamin D resistant rickets and achondroplasia). Alternate sections were used for histochemical localization of glycosaminoglycans and proteins. The values were compared with those found in comparable zones of the growth plate from normal children of the same age. The chondroitin sulphate concentration (% of defatted dry wt.) in the normal epiphyseal plate increased from the resting zone towards the proliferating/hypertrophic zone; collagen exhibited a reverse trend. In some of the pathological biopsies the concentration of chondroitin sulphate was slightly decreased whereas that of collagen was slightly increased. A marked increase in the collagen concentration was found in achondroplasia. The solubility profiles of the cetylpyridinium complexes of the chondroitin sulphate fraction showed three main peaks with slight but characteristic differences in the various zones of the normal cartilage plate. Significant shifts in the proportion of these peaks were observed in several pathological biopsies, indicating possible deviations from the normal molecular characteristics of the chondroitin sulphate. Analysis of the main chondroitin sulphate fraction, obtained from pooled samples of normal tibial growth plate after fractionation on the macroscale, indicated that all three peaks contained both chondroitin-4 sulphate and chondroitin-6 sulphate and that they probably differed in their molecular weight.

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Gamma models for estimating the odds ratio for a skewed biomarker measured in pools and subject to errors

Biostatistics ◽

10.1093/biostatistics/kxz028 ◽

2019 ◽

Author(s):

Dane R Van Domelen ◽

Emily M Mitchell ◽

Neil J Perkins ◽

Enrique F Schisterman ◽

Amita K Manatunga ◽

...

Keyword(s):

Odds Ratio ◽

Adjusted Odds Ratio ◽

Lower Cost ◽

Cost Effective ◽

Ratio Estimation ◽

Statistical Efficiency ◽

Function Model ◽

Processing Error ◽

Wide Range ◽

Pooled Samples

SUMMARYMeasuring a biomarker in pooled samples from multiple cases or controls can lead to cost-effective estimation of a covariate-adjusted odds ratio, particularly for expensive assays. But pooled measurements may be affected by assay-related measurement error (ME) and/or pooling-related processing error (PE), which can induce bias if ignored. Building on recently developed methods for a normal biomarker subject to additive errors, we present two related estimators for a right-skewed biomarker subject to multiplicative errors: one based on logistic regression and the other based on a Gamma discriminant function model. Applied to a reproductive health dataset with a right-skewed cytokine measured in pools of size 1 and 2, both methods suggest no association with spontaneous abortion. The fitted models indicate little ME but fairly severe PE, the latter of which is much too large to ignore. Simulations mimicking these data with a non-unity odds ratio confirm validity of the estimators and illustrate how PE can detract from pooling-related gains in statistical efficiency. These methods address a key issue associated with the homogeneous pools study design and should facilitate valid odds ratio estimation at a lower cost in a wide range of scenarios.

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Inhibition Kinetics of 16 Organophosphorus Pesticides or Their Active Metabolites on Erythrocyte Acetylcholinesterase from Humans and Rats

Toxicological Sciences ◽

10.1093/toxsci/kfab031 ◽

2021 ◽

Author(s):

Edward C Meek ◽

Richard Reiss ◽

J Allen Crow ◽

Janice E Chambers

Keyword(s):

Kinetic Parameters ◽

Organophosphorus Pesticides ◽

Erythrocyte Ghost ◽

Inhibition Kinetics ◽

Active Metabolites ◽

Adult Rats ◽

Resultant Data ◽

Wide Range ◽

High Level ◽

Pooled Samples

Abstract Inhibition kinetics assays were conducted with 16 commercial organophosphate (OP) pesticides or their metabolites on acetylcholinesterase (AChE) in erythrocyte “ghost” preparations from 18 individual humans (both sexes; adults, juveniles and cord blood samples; mixed races/ethnicities) and pooled samples from adult rats (both sexes). A well established spectrophotometric assay using acetylthiocholine as substrate and a chromogen was employed. The kinetic parameters bimolecular rate constant (ki), dissociation constant (KI) and phosphorylation constant (kp) were calculated for each compound. As expected, a wide range of potencies were displayed among the tested compounds. Statistical analysis of the resultant data indicated no differences in sex, age or race/ethnicity among the human samples that are unexpected based on chance (4.2% statistically significant out of 48 parameters calculated) and no differences between the sexes in rats. The bimolecular rate constants for 10 of the compounds were not statistically different between rats and humans. The data indicate that, consistent with the high level of conservation of AChE among species and the fact that AChE at different locations within a species arises from the same gene, the inhibition kinetic parameters calculated from rat erythrocyte ghost preparations should be useful in estimating potencies of OP compounds on target AChE in humans. Additionally the data indicate that differences in sensitivities among individual humans were not apparent. Impact Statement: These data are expected to be useful in consideration of the intraspecies and interspecies uncertainty factors in OP pesticide risk assessment.

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Reduced Variation in Drosophila simulans Mitochondrial DNA

Genetics ◽

10.1093/genetics/144.4.1519 ◽

1996 ◽

Vol 144 (4) ◽

pp. 1519-1528

Author(s):

J William O Ballad ◽

Joy Hatzidakis ◽

Timothy L Karr ◽

Martin Kreitman

Keyword(s):

Mitochondrial Dna ◽

Mitochondrial Genome ◽

Evolutionary Dynamics ◽

Selective Sweep ◽

Mitochondrial Gene ◽

Drosophila Simulans ◽

Dramatic Reduction ◽

Nucleotide Variability ◽

Pooled Samples ◽

Mitochondrial Gene Mutation

We investigated the evolutionary dynamics of infection of a Drosophila simulans population by a maternally inherited insect bacterial parasite, Wolbachia, by analyzing nucleotide variability in three regions of the mitochondrial genome in four infected and 35 uninfected lines. Mitochondrial variability is significantly reduced compared to a noncoding region of a nuclear-encoded gene in both uninfected and pooled samples of flies, indicating a sweep of genetic variation. The selective sweep of mitochondrial DNA may have been generated by the fixation of an advantageous mitochondrial gene mutation in the mitochondrial genome. Alternatively, the dramatic reduction in mitochondrial diversity may be related to Wolbachia.

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Levels of Polychlorinated Dibenzo-p-Dioxins/Furans (PCDD/Fs) and Dioxin-Like Polychlorinated Biphenyls (DL-PCBs) in Human Breast Milk in Chile: A Pilot Study

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18094825 ◽

2021 ◽

Vol 18 (9) ◽

pp. 4825

Author(s):

Claudia Foerster ◽

Liliana Zúñiga-Venegas ◽

Pedro Enríquez ◽

Jacqueline Rojas ◽

Claudia Zamora ◽

...

Keyword(s):

High Resolution ◽

Breast Milk ◽

Polychlorinated Biphenyls ◽

High Resolution Mass Spectrometry ◽

Daily Intake ◽

Human Breast Milk ◽

International Studies ◽

Cross Sectional ◽

Pooled Samples ◽

Chilean Women

Persistent organic pollutants (POPs) are organic compounds that resist biochemical degradation, moving long distances across the atmosphere before deposition occurs. Our goal was to provide up-to-date data on the levels of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in breast milk from Chilean women and to estimate the exposure of infants due to breast milk consumption. In Chile, we conducted a cross-sectional study based on methodologies proposed by the WHO, with a sample of 30 women recruited from three defined areas: 10 from the Arica Region (urban; Arica and Parinacota Region), 10 from Coltauco (rural; O’Higgins Region), and 10 from Molina (40% rural; Maule Region). High-resolution gas chromatography coupled with high-resolution mass spectrometry (HRGC/HRMS) was performed on pooled samples from each area. We calculated equivalent toxic concentrations (WHO-TEQ) based on the current WHO Toxic Equivalency Factors (TEF). The minimum and maximum values of ∑ PCDDs/Fs + DL-PCBs-TEQ were 4.317 pg TEQ/g fat in Coltauco and 6.31 pg TEQ/g fat in Arica. Molina had a total TEQ of 5.50 pg TEQ/g fat. The contribution of PCDD/Fs was approximately five-fold higher than that of DL-PCBs. The Estimated Daily Intake (EDI) of ∑ PCDDs/Fs + DL-PCBs based on the three pooled samples ranged between 6.71 and 26.28 pg TEQ/kg body weight (bw)/day, with a mean intake of 16.11 (±6.71) pg TEQ/kg bw/day in breastfed children from 0 to 24 months old. These levels were lower than those reported in international studies. Despite the fact that the observed levels were low compared to those in most industrialized countries, the detection of a variety of POPs in breast milk from Chilean women indicates the need for follow-up studies to determine whether such exposures during childhood could represent a health risk in adulthood.

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Heterogeneous Market Responses and the Listing Effect in M&A

Quarterly Journal of Finance ◽

10.1142/s2010139212500073 ◽

2012 ◽

Vol 02 (02) ◽

pp. 1250007 ◽

Cited By ~ 2

Author(s):

Qingzhong Ma ◽

David A. Whidbee ◽

Wei Zhang

Keyword(s):

Asymmetric Information ◽

Relative Size ◽

Conventional Approach ◽

Omitted Variables ◽

Market Responses ◽

Monitoring Mechanism ◽

Method Of Payment ◽

Pooled Samples

Unlisted acquisitions differ from listed ones in three important aspects: the possibility of forming blockholders, which substitute debt as a monitoring mechanism; the liquidity discount, which mitigates managerial hubris; and the distinct deal process through which two-sided asymmetric information is revealed. Due to these differences, same firm and deal characteristics could induce heterogeneous market responses, depending on the target listing status. We find that such heterogeneous responses exist in usual characteristics such as method of payment, relative size, acquirer size, leverage, and market-to-book ratios. After these heterogeneous responses are incorporated, the puzzling "listing effect" disappears. Our results also indicate that the conventional approach used to investigate pooled samples of listed and unlisted acquisitions is effectively misspecified due to omitted variables.

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Prevalence of methicillin-resistant Staphylococcus aureus among large commercial pig herds in South Africa

Onderstepoort Journal of Veterinary Research ◽

10.4102/ojvr.v85i1.1561 ◽

2018 ◽

Vol 85 (1) ◽

Cited By ~ 3

Author(s):

Shani Van Lochem ◽

Peter N. Thompson ◽

Cornelius H. Annandale

Keyword(s):

South Africa ◽

Staphylococcus Aureus ◽

South African ◽

Methicillin Resistant Staphylococcus Aureus ◽

Carrier Status ◽

Methicillin Resistant ◽

Herd Level ◽

Nasal Carrier ◽

Zoonotic Risk ◽

Pooled Samples

The prevalence of nasal carrier status of methicillin-resistant Staphylococcus aureus (MRSA) in pigs has been described elsewhere, but is unknown in South Africa. To address concerns that exist regarding the zoonotic risk that carriers pose to workers, the herd-level prevalence of MRSA was determined among 25 large (> 500 sows) commercial pig herds in South Africa, representing 45% of the large commercial herds in the country. From each herd, the nasal contents of 18 finisher pigs were sampled at the abattoir, pooled into three and selectively cultured to determine the presence of MRSA. A herd was classified as MRSA-positive if one or more of the three pooled samples cultured positive. Three of the 25 herds tested positive for MRSA, equating to a 12% herd prevalence (95% CI: 7% – 23%) among South African commercial piggeries. The prevalence of nasal MRSA carriers among large commercial pig herds in South Africa was low compared to what has been reported elsewhere and suggests a relatively low zoonotic MRSA risk to workers in South African commercial piggeries and abattoirs.

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