64 research outputs found
Stereoselective Bioaccumulation and Metabolite Formation of Triadimefon in <i>Tubifex tubifex</i>
Triadimefon, a chiral fungicide,
could be metabolized to triadimenol
which has two chiral centers. In this work, <i>Tubifex tubifex</i> was exposed to triadimefon through the aqueous and soil phase to
explore the relative importance of the routes of uptake. Bioaccumulation
of triadimefon in tubifex was detected in both treatments, and the
kinetics of the accumulation processes were significantly different
in these two experiments. In spiked water treatment, (<i>S</i>)-triadimefon was preferentially accumulated over the (<i>R</i>)-triadimefon, whereas the enantioselective bioaccumulation was not
detected in the spiked soil microenvironment. Simultaneously, four
stereoisomers of triadimenol were also found in the tubifex tissue.
Although the amount of these stereoisomers were different from each
other with relatively more accumulation of the most fungi-toxic stereoisomer
(1<i>S</i>,2<i>R</i>), the abundance ratios in
the two exposure treatments were similar at the same sampling, following
the order (1<i>S</i>,2<i>S</i>) > (1<i>R</i>,2<i>S</i>) > (1<i>R</i>,2<i>R</i>)
> (1<i>S</i>,2<i>R</i>). The bioaccumulation
factor
was calculated for parent compound triadimefon and metabolite enrichment
factor for metabolite. The results showed that both uptake routes,
epidermal contact in the aqueous phase and ingestion of solid particles
in soil, were important to the bioaccumulation of the triadimefon
and triadimenol in tubifex
Absorption, Distribution, Metabolism, and in Vitro Digestion of Beta-Cypermethrin in Laying Hens
Beta-cypermethrin (beta-CP), an important
pyrethroid insecticide,
and its main acid metabolites are frequently detected in human samples.
Because beta-CP may pose some risk to human health, we studied dynamics
and residues of beta-CP and its metabolites in hen egg, droppings,
blood, and 15 other tissues after continuous exposure. A digestive
model was then used to study beta-CP’s digestive fate. Beta-CP
and its metabolites significantly accumulated in tissues with high
lipid contents and were readily transferred to eggs. Beta-CP was mainly
metabolized into acid metabolites that accumulated in egg and edible
tissues of laying hens, suggesting that humans may be exposed to beta-CP
acid metabolites through food
Fate and Stereoselective Behavior of Benalaxyl in a Water–Sediment Microcosm
The
environmental behavior and stereoselectivity of the chiral
fungicide benalaxyl and its chiral metabolite benalaxyl acid in water,
sediment, and water–sediment microcosms were studied. The microcosms
were incubated at 25 °C with light or under darkness. The influencing
factors such as light and microorganism were investigated. The results
showed that benalaxyl had half-lives of >21 days in the microcosm
system and that the metabolite benalaxyl acid could exist in the microcosm
for >70 days. Benalaxyl was mainly transformed through microbial
degradation,
and thus sediment microorganisms played a major role in the dissipation
of benalaxyl in the aquatic microcosm. The stereoselective behavior
of benalaxyl and benalaxyl acid was also investigated. (−)-Benalaxyl
was preferentially degraded in the microcosm, resulting in an enrichment
of the more toxic enantiomer (+)-benalaxyl, which may cause higher
risk to the aquatic system. Moreover, (−)-benalaxyl acid was
preferentially formed in the microcosm. The enantioselectivity of
the enantiomers in the microcosm should be taken into consideration
for an accurate risk assessment
Nonoccupational Exposure to Pyrethroids and Risk of Coronary Heart Disease in the Chinese Population
Pyrethroids and the metabolites have
been frequently observed in
the environment. Animal data suggests that pyrethroids can induce
adverse effect on the cardiovascular system but there are no human
studies examining pyrethoids exposure as a risk for coronary heart
disease (CHD). We analyzed three nonspecific pyrethroids metabolites
in urine and studied the association with CHD risk. A total of 72
CHD patients and 136 healthy subjects were recruited in Shanxi province
in China from 2013 to 2014 by matching age and gender. The median
concentrations of urinary cis-CDDA (cis-3-(2,2-dichlorovinyl)-2,2-dimethyl
cyclopropane carboxylic acid), trans-CDDA (trans-3-(2,2-dichlorovinyl)-2,2-dimethyl
cyclopropane carboxylic acid) and 3-PBA (3-phenoxybenzoic acid) among
healthy subjects were 1.03, 0.42, 0.74 μg/L respectively, while
the median concentrations of the three metabolites among CHD patients
were 1.93, 1.07, 1.09 μg/L respectively, significantly higher
than healthy subjects. Upper tertile of urinary pyrethroid metabolites
were associated with an increased risk of CHD compared with the lowest
tertile (cis-CDDA: OR<sub>T3vsT1</sub> = 6.86, 95% CI: 2.76–17.06, <i>p</i>-trend = 0.000; trans-CDDA: OR<sub>T3vsT1</sub> = 6.94;
95% CI: 2.80–17.19; <i>p</i>-trend =0.000; 3-PBA:
OR<sub>T3vsT1</sub> = 3.62; 95% CI: 1.48–8.88; <i>p</i>-trend = 0.009; total pyrethroid metabolites: OR<sub>T3vsT1</sub> = 4.55; 95% CI: 1.80–11.54; <i>p</i>-trend = 0.002).
This study provides information on pyrethroids exposure in China and
reveals a possible positive association between pyrethroids exposure
and the risk of coronary heart disease
Bioinspired Structures Made of Silicone Nanofilaments for Upcycling Waste Masks to Reusable N95 Respirators
The increasing demand for personal protective equipment
such as
single-use masks has led to large amounts of nondegradable plastic
waste, aggravating economic and environmental burdens. This study
reports a simple and scalable approach for upcycling waste masks via
a chemical vapor deposition technique, realizing a trichome-like biomimetic
(TLB) N95 respirator with superhydrophobicity (water contact angle
≥150°), N95-level protection, and reusability. The TLB
N95 respirator comprising templated silicone nanofilaments with an
average diameter of ∼150 nm offers N95-level protection and
breathability comparable to those of commercial N95 respirators. The
TLB N95 respirator can still maintain its N95-level protection against
particulate matter and viruses after 10 disinfection treatment cycles
(i.e., ultraviolet irradiation, microwave irradiation, dry heating,
and autoclaving), demonstrating durable reusability. The proposed
strategy provides new insight into upcycle waste masks, breaking
the existing design and preparation concept of reusable masks
Enantioselective Metabolism of Quizalofop-Ethyl in Rat
<div><p>The pharmacokinetic and distribution of the enantiomers of quizalofop-ethyl and its metabolite quizalofop-acid were studied in Sprague-Dawley male rats. The two pairs of enantiomers were determined using a validated chiral high-performance liquid chromatography method. Animals were administered quizalofop-ethyl at 10 mg kg<sup>−1</sup> orally and intravenously. It was found high concentration of quizalofop-acid in the blood and tissues by both intragastric and intravenous administration, and quizalofop-ethyl could not be detected through the whole study which indicated a quick metabolism of quizalofop-ethyl to quizalofop-acid in vivo. In almost all the samples, the concentrations of (+)-quizalofop-acid exceeded those of (−)-quizalofop-acid. Quizalofop-acid could still be detected in the samples even at 120 h except in brain due to the function of blood-brain barrier. Based on a rough calculation, about 8.77% and 2.16% of quizalofop-acid were excreted through urine and feces after intragastric administration. The oral bioavailability of (+)-quizalofop-acid and (−)-quizalofop-acid were 72.8% and 83.6%.</p></div
Bioinspired Structures Made of Silicone Nanofilaments for Upcycling Waste Masks to Reusable N95 Respirators
The increasing demand for personal protective equipment
such as
single-use masks has led to large amounts of nondegradable plastic
waste, aggravating economic and environmental burdens. This study
reports a simple and scalable approach for upcycling waste masks via
a chemical vapor deposition technique, realizing a trichome-like biomimetic
(TLB) N95 respirator with superhydrophobicity (water contact angle
≥150°), N95-level protection, and reusability. The TLB
N95 respirator comprising templated silicone nanofilaments with an
average diameter of ∼150 nm offers N95-level protection and
breathability comparable to those of commercial N95 respirators. The
TLB N95 respirator can still maintain its N95-level protection against
particulate matter and viruses after 10 disinfection treatment cycles
(i.e., ultraviolet irradiation, microwave irradiation, dry heating,
and autoclaving), demonstrating durable reusability. The proposed
strategy provides new insight into upcycle waste masks, breaking
the existing design and preparation concept of reusable masks
Calibration data of QE and QA enantiomers in different sample matrixes.
<p>Calibration data of QE and QA enantiomers in different sample matrixes.</p
Enantioselective Characteristics and Montmorillonite-Mediated Removal Effects of α‑Hexachlorocyclohexane in Laying Hens
α-Hexachlorocyclohexane
(α-HCH) is a chiral organochlorine
pesticide that is often ubiquitously detected in various environmental
matrices and may be absorbed by the human body via food consumption,
with serious detriments to human health. In this study, enantioselective
degradation kinetics and residues of α-HCH in laying hens were
investigated after a single dose of exposure to the pesticide, whereas
enantioselectivity and residues of α-HCH in eggs, droppings,
and various tissues were investigated after long-term exposure. Meanwhile,
montmorillonite (MMT), a feed additive with high capacity of adsorption,
was investigated for its ability to remove α-HCH from laying
hens. Most non-brain tissues enantioselectively accumulated (−)-α-HCH,
while (+)-α-HCH was preferentially accumulated in the brain.
The enantiomer fractions (EFs) in most tissues gradually decreased,
implying continuous depletion of (+)-α-HCH in laying hens. After
30 days of exposure and 31 days of elimination, the concentration
of α-HCH in eggs and tissues of laying hens with MMT-containing
feed was lower than that with MMT-free feed, indicating the removal
effects of MMT for α-HCH in laying hens. The findings presented
herein suggest that modified MMT may potentially be useful in reducing
the enrichment of α-HCH in laying hens and eggs, thus lowering
the risk of human intake of α-HCH
Pharmacokinetic parameters and bioavailability of QA after intravenous and oral administration (n = 6).
<p>Pharmacokinetic parameters and bioavailability of QA after intravenous and oral administration (n = 6).</p
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