Tire and road wear
particles (TRWP) have been shown to represent
a large part of anthropogenic particles released into the environment.
Nevertheless, the potential ecological risk of TRWP in the different
environmental compartments and their potential toxic impacts on terrestrial
and aquatic organisms remain largely underinvestigated. Several heavy
metals compose TRWP, including Zn, which is used as a catalyst during
the vulcanization process of rubber. This study investigated the solubilization
potential of metals from cryogenically milled tire tread (CMTT) and
TRWP in simulated gastric fluids (SFGASTRIC) and simulated
intestinal fluids (SFINTESTINAL) designed to mimic rainbow
trout (Oncorhynchus mykiss) gastrointestinal
conditions. Our results indicate that the solubilization of heavy
metals was greatly enhanced by gastrointestinal fluids compared to
that by mineral water. After a 26 h in vitro digestion,
9.6 and 23.0% of total Zn content of CMTT and TRWP, respectively,
were solubilized into the simulated gastrointestinal fluids. Coingestion
of tire particles (performed with CMTT only) and surrogate prey items
(Gammarus pulex) demonstrated that
the animal organic matter reduced the amount of bioavailable Zn solubilized
from CMTT. Contrastingly, in the coingestion scenario with vegetal
organic matter (Lemna minor), high
quantities of Zn were solubilized from L. minor and cumulated with Zn solubilized from CMTT.
Lipoprotein lipase (LPL) plays a crucial role in preventing dyslipidemia by hydrolyzing triglycerides (TGs) in packaged lipoproteins. Since hypertriglyceridemia (HTG) is a major risk factor for cardiovascular disease (CVD), the leading cause of death worldwide, methods that accurately quantify the hydrolytic activity of LPL in clinical and pre-clinical samples are much needed. To date, the methods used to determine LPL activity vary considerably in their approach, in the LPL substrates used, and in the source of LPL activators and inhibitors used to quantify LPL-specific activity, rather than other lipases, e.g., hepatic lipase (HL) or endothelial lipase (EL) activity. Here, we describe methods recently optimized in our laboratory, using a synthetic ApoC-II peptide to activate LPL, and an n-terminal Angiopoietin-Like 4 fragment (nAngptl4) to inhibit LPL, presenting a cost-effective and reproducible method to measure LPL activity in human post-heparin plasma (PHP) and in LPL-enriched heparin released (HR) fractions from LPL secreting cells. We also describe a modified version of the triolein-based assay using human serum as a source of endogenous activators and inhibitors and to determine the relative abundance of circulating factors that regulate LPL activity. Finally, we describe how an ApoC-II peptide and nAngptl4 can be applied to high-throughput measurements of LPL activity using the EnzChek™ fluorescent TG analog substrate with PHP, bovine LPL, and HR LPL enriched fractions. In summary, this manuscript assesses the current methods of measuring LPL activity and makes new recommendations for measuring LPL-mediated hydrolysis in pre-clinical and clinical samples.
The sorption of Hydrophobic Organic Compound (HOC) onto microplastics is relatively well reported in the literature, while their desorption remains poorly investigated, and especially in biological fluids. The present study...
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