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Lipid-Based Nanoformulations from Plants for Sustainable Drug Delivery
Published in Madhu Gupta, Durgesh Nandini Chauhan, Vikas Sharma, Nagendra Singh Chauhan, Novel Drug Delivery Systems for Phytoconstituents, 2020
Ilaria Clemente, Ilaria Colzi, Sara Falsini
Beyond the Folch approach, Bligh and Dyer (1959) and later, Sheppard (1963) introduced new extraction procedures. The former foresees the use of the same solvents but in comparison with the Folch solution, Bligh and Dyer proposed a chloroform-methanol step-wise extraction of 1:2 and 1:1 (v/v) in a final amount of only four times with respect to the starting material (Axelsson et al., 2014). The latter envisages the employment of the mixture ethanol/diethyl ether for lipid extraction. More recently, a simple methyl tert-butyl ether (MTBE)-based extraction has been proposed for the simultaneous extraction of lipophilic metabolites and lipids from small amounts of tissue sample (Matyash et al., 2008).
Risk Assessment
Published in David Woolley, Adam Woolley, Practical Toxicology, 2017
In terms of legislation in Europe, the regulatory framework for environmental risk assessment is based on the risk quotient, which is the ratio of the predicted environmental concentration (PEC) to the predicted environmental no-effect concentration (PNEC). Typically, the PEC is modeled using data on expected market volume and usage data, together with estimations of diffuse or point-source introduction, degradation, distribution, and fate. In some cases, these predictions are supported by analytical measurement. The PNEC is then estimated by using empirically derived effect or no-effect data from laboratory experiments, applying safety factors of up to 1000 depending on the uncertainties inherent in the test data. A risk characterization ratio (the PEC divided by the PNEC) of less than 1 indicates low risk, while a ratio greater than 1 may indicate a relevant risk. The margins of safety (MOSs) are also considered; the risk decreases with increasing MOS. This process and the reasoning involved are nicely outlined in an environmental risk assessment of methyl tertiary butyl ether (MTBE) carried out by a team from the European Fuel Oxygenates Association (EFOA), WRc-NSF National Centre for Environmental Toxicology (NCET), and European Centre for Eco-toxicology and Toxicology of Chemicals (ECETOC). This assessment is summarized in Case Study 18.2.
Derivation and Modeling of Mechanistic Data for Use in Risk Assessment
Published in John C. Lipscomb, Edward V. Ohanian, Toxicokinetics and Risk Assessment, 2016
The physiological model was also used to examine the dependence of renal α2u accumulation on ligand-binding affinity and ligand dosimetry. For high-binding affinity ligands, the model predicts that accumulation of α2u in the kidney saturates even at relatively low cumulative concentrations of unbound ligand in the blood. For chemicals with low-binding affinities such as MTBE (63), little renal accumulation of α2u is predicted even at high doses. This prediction is consistent with the experimental data on renal α2u accumulation in male rats exposed to MTBE (58). Thus, the extent of proximal tubule necrosis and increased renal cell proliferation in rats exposed to MTBE (58) is likely not due simply to α2u accumulation and probably involves toxicity from MTBE metabolites (64). Human risk assessments of agents that are associated with α2u accumulation should also consider the possible contribution of toxic metabolites to the nephrotoxic response.
Adverse outcome pathway (AOP): α2u-globulin nephropathy and kidney tumors in male rats
Published in Critical Reviews in Toxicology, 2022
Katy O. Goyak, Satinder S. Sarang, A. Franzen, Susan J. Borghoff, Jessica P. Ryman-Rasmussen
Sustained cell proliferation and clonal expansion of the renal tubular cells lead to a cellular environment leading to tumorigenic response (Tables 1(A,B); see Borghoff et al. 1990, 2001, 2015; Borghoff and Lagarde 1993; Lehman-McKeeman et al. 1990; Swenberg 1993; Prescott-Matthews et al. 1999). The extent of this sustained cell proliferation is seen in the observation of atypical hyperplasia in the kidneys of male rats. Inhalation exposure to 3000 ppm MTBE caused an increased incidence of kidney tumors in male rats, but not female rats or mice (Bird et al. 1997; Prescott-Matthews et al. 1999). TBA was also reported to induce kidney tumors in male rats following exposure in drinking water (Cirvello et al. 1995; NTP 1995). A diverse group of chemicals has been identified to cause kidney tumors in male but not female rats (Swenberg et al. 1989; Borghoff et al. 1990; US EPA 1991; IARC 1999; Swenberg and Lehman-McKeeman 1999; Doi et al. 2007).
An overview of lipidomics utilizing cadaver derived biological samples
Published in Expert Review of Proteomics, 2021
Luheng Lyu, Neel Sonik, Sanjoy Bhattacharya
Extraction methods: The largest variability in quantification can be introduced by the method of extraction. Three commonly utilized extraction methods are: Methyl tertiary-butyl ether (MTBE) method [24]: This method offers the advantage of quick extraction. The upper phase is extracted so that no interference from any other liquid or interphase layer is experienced.Bligh-Dyer method [25]: This is one of the most commonly used methods for extraction of lipids from bodily fluids and tissues.The Folch method [26]: considered the gold standard for lipid extraction but a relatively time-consuming procedure.
A comparison of levels of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in raw and cooked fish
Published in Toxin Reviews, 2021
Şana Sungur, Erdi Kanan, Muaz Köroğlu
About 1 g of sample was homogenized with 5 ml of high-purity Milli-Q water (Millipore, Billerica, MA). One milliliters of 0.5 M tetrabutylammonium hydrogen sulfate solution and 2 ml of sodium carbonate buffer (0.25 M, pH 10) were added to 1 ml of the homogenate samples in a PP tube and thoroughly mixed for extraction. Five milliliters of methyl tert-butyl ether (MTBE) were added to the prepared mixture and shaken for 20 min. The organic and aqueous layers were separated by centrifugation, and an exact volume of MTBE (4 ml) was removed from the solution. The aqueous mixture was rinsed with MTBE and separated twice; both the rinses were combined in a second PP tube. The solvent was evaporated under nitrogen and replaced with 0.5 ml of methanol. This extract was passed through a nylon mesh filter (0.2 μm) into an High Performance Liquid Chromatography (HPLC) vial. The extraction blanks were prepared using Milli-Q water (Guerranti et al. 2013, Corsolini et al. 2008).