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Biochemical Methods of Studying Hepatotoxicity
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
Prasada Rao S. Kodavanti, Harihara M. Mehendale
The substrate is colorless, while p-nitroaniline absorbs strongly at A405. Thus, measure the amount of p-nitroaniline liberated kinetically at A405 and this is proportional to the γ-GT activity.
The Dose Response of Percutaneous Absorption
Published in Rhoda G. M. Wang, James B. Knaak, Howard I. Maibach, Health Risk Assessment, 2017
Ronald C. Wester, Howard I. Maibach
The dose response of p-nitroaniline with skin is shown in Figure 6 and 7. In Figure 6, p-nitroaniline partitions from water into powdered human stratum corneum. In Figure 7, the concentrations of p-nitroaniline in human skin and subsequently absorbed through the skin are shown. The data show that the percent doses are the same for the tenfold dose range. If the percent doses are the same, then the dose response is linear.1
PDMS networks meet barnacles: a complex and often toxic relationship
Published in Biofouling, 2022
Daniel Rittschof, Beatriz Orihuela, Jan Genzer, Kirill Efimenko
The laboratory studies reported the acute toxicity of PDMS networks to larvae (Rittschof and Holm 1997; Holm et al. 2005; Rittschof et al. 2008). Even thin films of PDMS require leaching in running seawater for one to two months before barnacle larvae can be set on the surface in static conditions (Holm et al. 2005). Our tests with leachates from PDMS network components and a model enzyme, trypsin, and a trypsin-specific substrate support the hypothesis that leachates from components impact enzyme activity. The enzyme activity was measured for leachates of PDMSe components with trypsin by evaluating p-nitroaniline production. Three solvents were tested. AFSW was our control and resulted in predicted production. The addition of small amounts of methanol stimulated p-nitroaniline production. Dry toluene inhibited product production. Results from leachates of PDMS, small DMS cycles, and the crosslinker were enlightening. The production of p-nitroaniline was enhanced three- to eightfold upon addition to all tested formulations. Leachates from the Pt catalyst killed the enzyme at extremely low concentrations. Thus, the relation between this model enzyme, its substrate, and PDMSe leachates is complex.
Microwave assisted green synthesis of silver nanoparticles using leaf extract of elephantopus scaber and its environmental and biological applications
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Sijo Francis, Siby Joseph, Ebey P. Koshy, Beena Mathew
The hydrogenation of 4-nitrophenol to 4-aminophenol, 2-nitroaniline to 1, 2-phenylenediamine and 4-nitroniline to 1, 4-phenylenediamine by NaBH4 were taken as model reactions and performed in the presence of the newly synthesized silver nanocatalyst. 2 ml of 4-nitrophenol (8 × 10−5 M) was placed in a quartz cuvette along with 0.5 ml freshly prepared NaBH4 (0.06 M) and 0.5 ml of AgNP-E. scaber (0.04 mg/mL). UV-vis spectra were continuously recorded till the completion of the reaction which was indicated by the disappearance of the initial reactant peaks in the electronic spectra. The reaction was conducted with 2-/4-nitroaniline (6 × 10−5 M) instead of 4-nitrophenol. The kinetics of the reduction reactions were examined by recording the absorbance at wavelength 400, 412 and 380 nm for 4-nitrophenol, 2-nitroaniline and 4-nitroaniline respectively, using UV-vis spectrophotometer in the range 200–800 nm.
Analysis of cytotoxic effects of nickel on human blood lymphocytes
Published in Toxicology Mechanisms and Methods, 2018
Mohammad Hadi Zarei, Seyed Farshad Hosseini Shirazi, Marjan Aghvami, Ahmad Salimi, Jalal Pourahmad
Sigma’s caspase-3 assay kit (CASP-3-C) was utilized for the determination of caspase-3 activity in lysate of human lymphocytes after treatment with nickel. Briefly, hydrolyze of caspase-3 substrate (Ac-DEVD-pNA) by caspase-3 in cell lysate resulted in release of p-nitroaniline moiety that has high absorbance at 405 nm. Concentration of p-nitroaniline was determined through the use of p-nitroaniline absorbance at 405 nm in our sample and p-nitroaniline calibration curve (Hosseini et al. 2013; Seydi et al. 2015).