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Ecology
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
Guo et al. (2018) performed a systematic study on the phage MS2, as well as φX174 and T4, inactivation by surface plasma in argon mixed with 1% air and plasma-activated water. The inactivation of the phages was alleviated by the singlet oxygen scavengers, demonstrating that singlet oxygen played a primary role in this process. The reactive species generated by plasma damaged both nucleic acids and proteins, consistent with the morphological examination showing that plasma treatment caused the phage aggregation. Remarkably, prolonged storage had marginal effects on the antiviral activity of plasma-activated water (Guo et al. 2018).
Engineering Stable Spray-Dried Biologic Powder for Inhalation
Published in Anthony J. Hickey, Sandro R.P. da Rocha, Pharmaceutical Inhalation Aerosol Technology, 2019
Nicholas Carrigy, Reinhard Vehring
Biologic powders have been packaged to protect against moisture using heat-sealed aluminum foil bags containing desiccant [49,52]. It is crucial that there are no humidity excursions during the stability testing period, which can last on the order of years; hence, double packaging and double heat sealing are recommended. In addition to desiccant, for some biologics, it may be useful to add antioxidant and perform a nitrogen purge when packaging [59,255]. Instead of an external antioxidant pack, excipients such as ascorbic acid can be added to the spray drying formulation to work as an oxygen scavenger [18].
The Modification of Carboxyl Groups
Published in Roger L. Lundblad, Claudia M. Noyes, Chemical Reagents for Protein Modification, 1984
Roger L. Lundblad, Claudia M. Noyes
Diazo compounds have proved useful for some time in the esterification of the carboxyl groups of proteins. This is particularly true of diazomethane. The use of this compound was reviewed 15 years ago by the late Philip Wilcox,10, 11 and we are not aware of the extensive use of this compound during the past decade. Various α-keto diazo derivatives have proved particularly fruitful in the study of acid proteinases. Rajagopalan, Stein, and Moore12 demonstrated that pepsin was inactivated by diazoacetyl-L-norleucine methyl ester. During the course of these studies, it was observed that cupric ions greatly enhanced both the rate and specificity of the modification. Originally it was suggested that cupric ions blocked nonspecific reaction with carboxyl groups not at the active site. Subsequently it was shown that cupric ions and diazoacetyl-norleucine methyl ester formed a highly reactive species, presumably a copper-complexed carbene, which then reacted with a specific protonated carboxyl group at the active site of pepsin.13, 14 The modification of carboxyl groups in a variety of acid proteinases with a variety of α-keto diazo compounds is shown in Table 1. These diazo compounds are by no means specific for carboxyl group modification in protein. Benzyl-oxycarbonyl-phenylalanyldiazomethylketone has been shown to modify cathepsin B,, presumably by reaction with the active site sulfhydryl group.15 Other possible side reactions of α-keto diazo compounds have been reviewed by Widner and Viswanatha.16 These side reactions result primarily from the oxidative modification of tryptophan, methionine, tyrosine, and cystine. These side reactions can be virtually obviated by vigorous exclusion of oxygen from the reaction and the addition of an oxygen scavenger (e.g., Na2S204).
Evaluation of hepatorenal protective activity of Moringa oleifera on histological and biochemical parameters in cadmium intoxicated rats
Published in Toxin Reviews, 2019
The antioxidant activity of Moringa is mainly due to its content of many phenolic compounds as previously mentioned (Karthivashan et al. 2013). These phenolic compounds are multifactorial defenders against oxidative stress. This is because they can act as reducing agents via singlet oxygen scavengers and hydrogen atom donators with subsequent stabilization of the produced free radicals forming stable compounds that do not initiate or propagate oxidation. In addition, the involvement of the anti-inflammatory and analgesic activities of such phenolic compounds in both plants in the protective mechanisms cannot be neglected. Further, phenolic compounds including flavonoids can protect the cells against emptying reduced glutathione (GSH) via activating the activity of glutathione reductase as well as increasing the activities of other antioxidant enzymes which are ultimately helpful in renal and hepatic protection (Adeyemi and Elebiyo 2014).
Radioprotective efficacy of Ginkgo biloba and Angelica archangelica extract against technetium-99m-sestamibi induced oxidative stress and lens injury in rats
Published in International Journal of Radiation Biology, 2018
Mahmoud H. Khedr, Medhat W. Shafaa, Amany Abdel-Ghaffar, Ahmed Saleh
CAT is an inducible enzyme that decomposes H2O2, and is involved in the antioxidant defense mechanisms of mammalian cells. Thus, it is an index of increased H2O2 production (Meneghini 1997). This might explain the higher CAT activity demonstrated in the blood of irradiated rats (GI) than in controls. The decreased activities of CAT in the lens tissue of rats injected with 99mTc sestamibi indicate a highly reduced capacity to subsist H2O2 produced in the lens tissue in response to acute stress (Halliwell and Gutteridge 1990). CAT can convert H2O2 into water and molecular oxygen. Therefore, the decreased CAT activity in tissue indicates a high degree of oxidative stress resulting in increased endogenous H2O2. SOD has been established to work in tandem with CAT to remove 2O2, respectively (Blokhina et al. 2003). Thus they are endogenous catalytic oxygen scavengers, and play key roles in cellular defense against reactive oxygen species under physiological conditions. Therefore, changes in CAT and SOD have been used as an index of oxidative stress.
Chitosan nanoparticles induced the antitumor effect in hepatocellular carcinoma cells by regulating ROS-mediated mitochondrial damage and endoplasmic reticulum stress
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Yibing Jiang, Xiwei Yu, Chang Su, Liang Zhao, Yijie Shi
In order to determine the generation of ROS induced by the treatment of CS NPs, we use fluorescent probe DCFH-DA to investigate the extent of oxidative stress. After entering the cell, DCFH-DA is hydrolyzed by esterase into DCFH which was further oxidized to fluorescent DCF by the help of the reactive oxygen species in the cells. Therefore, the fluorescence intensity of DCF can directly reflect the level of reactive oxygen species in the cell. As can be seen in Figure 3, the intracellular fluorescence intensity in CS NPs (1 mg/mL) treated cells was significantly higher than that of the control (p < .05), and the bright green fluorescence was distributed in a granular manner within the cytoplasm. After giving CS NPs to SMMC-7721 cells, the amount of intracellular ROS detected was 2.0 times at 12 h, 2.5 times at 24 h and 3.1 times at 48 h higher than that of the control group, indicating that CS NPs accelerated the production of intracellular ROS. After co-treatment of cells with CS NPs and N-acetylcysteine (NAC) as a commonly used active oxygen scavenger, the intracellular fluorescence intensity was significantly weaker than that of CS NPs alone (p < .05). The amount of ROS produced in cells was reduced significantly and ROS levels were reduced to 1.2 times in 12 h, 1.3 times in 24 h and 1.6 times in 48 h higher than that of the control group in SMMC-7721 cells. In contrast, the results demonstrated that there was no considerable difference on the intracellular fluorescence intensity of DCF in cells either treated with CS NPs or the combination of CS NPs and Eeyarestatin I (ESI) as a commonly used inhibitor of the ER. All results demonstrated that CS NPs could increase the content of ROS in SMMC-7721 cells. The use of ER inhibitors induced a negligible variation in ROS levels in cells, indicating that inhibition of endoplasmic stress as a downstream signalling pathway did not affect the production of ROS.