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Microsurgery in the Portal Area of the Rat
Published in Waldemar L. Olszewski, CRC Handbook of Microsurgery, 2019
A mere 12 days after the shunt, the activities of both F-6-PK and GPDH were already increased, and were higher still on day 24. The activity of G-6-PDH, the opening enzyme of the pentose-phosphate cycle ran parallel (Figure 8). Partly, the activities of glycolytic enzymes remained stable.
Assessment of Hepatocarcinogenesis by Early Indicators
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
Norio Hirota, Gary M. Williams
Bannasch (1968) first reported that nitrosomorpholine-induced foci displayed extensive storage of glycogen and related the occurrence of hepatoma in human cases of glycogen storage disease to changes in carbonhydrate metabolism during liver carcinogenesis. Subsequently, glycogen-storing foci were demonstrated with other types of carcinogens (Williams et al., 1976). This abnormality is seen more distinctly as persistent retention of cellular glycogen after fasting for 24–36 h (Figure 10), appearing to be related at least in part to a deficiency of G-6-P in foci cells (Bannasch and Angerer, 1974; Hirota and Williams, 1979b; Hirota and Yokoyama, 1985). In a comparative study of glycogen-storage abnormality and other phenotypic changes during hepatocarcinogenesis by 2-acetylaminofluorene in rats, foci and nodules rich in glycogen storage account for a majority of all lesions over the course of experiment, while lesions devoid of glycogen storage gradually increased in number during maintenance. The glycogen-deficient lesions (Figure 11) displayed hyperbasophilia and often GGT negativity suggesting that they are important precursors for malignant transformation (Hirota and Yokoyama, 1985). The glycogen-deficient cells with the possible highest potential to malignancy are ultrastructurally characterized by numerous polyribosomes lying free in the cytoplasmic matrix (Hirota and Williams, 1982), which is a general feature common to fast-growing populations of cells (Ghadially, 1975). This subcellular alteration accounting for cytoplasmic basophilia is compatible with acceleration of pentose-phosphate cycle with increased biochemical activity of glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase in basophilic foci and nodules as well as carcinomas (unpublished data). The demonstration of increased glucose-6-phosphate dehydrogenase (Bannasch et al., 1984; Klimek et al., 1984) as a rather late alteration during liver cell carcinogenesis is indicative that early changes such as decrease in the activity of L-pyruvate kinase (Fischer et al., 1987) and increase of uridine diphosphate glucuronyltransferase (Fischer et al., 1983) may be largely shifted, with time, to pentose-phosphate shunt which fuels synthesis of RNA and DNA.
Purification and characterisation of glutathione reductase from scorpionfish (scorpaena porcus) and investigation of heavy metal ions inhibition
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Glutathione reductase (EC 1.8.1.7; GR), a major enzyme in glutathione metabolism, is required for the maintenance of the reduced form of cellular glutathione, which is strongly nucleophilic for many reactive electrophiles10,11. The flavin enzyme GR acts as an antioxidant to protect cells from oxidative stress by reducing glutathione disulphide (GSSG) to its reduced form (GSH)12. It has an important role in the drug and detoxification mechanisms especially in the liver. This is due to the cytochrome P-450 system found in liver microsomes, which provides detoxifying events13. Maintaining the GSH/GSSG ratio in the cell environment is one of the most important known targets of the GR enzyme-catalysed reactions14. Glutathione reductase is involved in the reduction-oxidation of intracellular glutathione for GSSG, which is generated through the detoxification of hydroperoxides and reduction of some other chemicals catalysed by glutathione perdoxidase15. The NADP+ dependent malate dehydrogenase and pentose phosphate pathways provide the NADPH needed in this catalytic process16,17. NADPH, a key product of the pentose phosphate cycle, is employed extensively in reductive biosynthesis. Furthermore, it aids in the protection of the cell against oxidative damage9.
Nonlinearities in the cellular response to ionizing radiation and the role of p53 therein
Published in International Journal of Radiation Biology, 2021
David Murray, Razmik Mirzayans
Another antioxidant pathway of relevance to cellular radiosensitivity and that engages in crosstalk with p53 involves the redox factor-1 (Ref1) protein. Ref1 is a redox-dependent transcription coactivator that, under oxidative stress conditions, can stimulate the binding of redox-sensitive transcription factors such as p53 and activator protein-1 (AP-1) to their target promoters (Jayaraman et al. 1997; Gaiddon et al. 1999; Ueno et al. 1999; Spitz et al. 2004; Tell et al. 2009) leading to suppression of ROS. As seen with the co-activation of AP-1 by Ref1 (Spitz et al. 2004), this effect is mediated by a redox signal that originates in the cytoplasm involving sequential pentose phosphate cycle/TrxR-Trx-Ref1 cysteine oxidation-driven events. In this pathway, TrxR reduces Trx which translocates to the nucleus and reduces Ref1. Ref1 in turn functionally activates p53, presumably via the reduction of key cysteine residues (as in the case of AP-1), enhancing the transcription of p53-dependent genes (including p21) as well as p53’s pro-apoptotic functions (Ueno et al. 1999; Tell et al. 2009).
Cognitive function improvement after fecal microbiota transplantation in Alzheimer’s dementia patient: a case report
Published in Current Medical Research and Opinion, 2021
Soo-Hyun Park, Jung Hwan Lee, Jongbeom Shin, Jun-Seob Kim, Boram Cha, Suhjoon Lee, Kye Sook Kwon, Yong Woon Shin, Seong Hye Choi
Functional biomarker analysis using the Kruskal-Wallis H test was performed between the pre- and post-FMT groups by using EzBio-Cloud Apps (ChunLab Inc., Seoul, Korea). Pentose phosphate cycle, the functional pathway associated with the production of SCFA, was found to be significantly different between before and after FMT (p = .026)17.