scholarly journals Supplemental Ascorbate Diminishes DNA Damage Yet Depletes Glutathione and Increases Acute Liver Failure in a Mouse Model of Hepatic Antioxidant System Disruption

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 359
Author(s):  
Colin G. Miller ◽  
Jean A. Kundert ◽  
Justin R. Prigge ◽  
Julie A. Amato ◽  
Allison E. Perez ◽  
...  
Keyword(s):  
Dna Damage ◽  
Oxidative Damage ◽  
Liver Failure ◽  
Thioredoxin Reductase ◽  
Antioxidant Systems ◽  
Term Survival ◽  
Stress Markers ◽  
Thioredoxin Reductase 1 ◽  
Mock Treatment ◽  
Hepatocyte Necrosis

Cellular oxidants are primarily managed by the thioredoxin reductase-1 (TrxR1)- and glutathione reductase (Gsr)-driven antioxidant systems. In mice having hepatocyte-specific co-disruption of TrxR1 and Gsr (TrxR1/Gsr-null livers), methionine catabolism sustains hepatic levels of reduced glutathione (GSH). Although most mice with TrxR1/Gsr-null livers exhibit long-term survival, ~25% die from spontaneous liver failure between 4- and 7-weeks of age. Here we tested whether liver failure was ameliorated by ascorbate supplementation. Following ascorbate, dehydroascorbate, or mock treatment, we assessed survival, liver histology, or hepatic redox markers including GSH and GSSG, redox enzyme activities, and oxidative damage markers. Unexpectedly, rather than providing protection, ascorbate (5 mg/mL, drinking water) increased the death-rate to 43%. In adults, ascorbate (4 mg/g × 3 days i.p.) caused hepatocyte necrosis and loss of hepatic GSH in TrxR1/Gsr-null livers but not in wildtype controls. Dehydroascorbate (0.3 mg/g i.p.) also depleted hepatic GSH in TrxR1/Gsr-null livers, whereas GSH levels were not significantly affected by either treatment in wildtype livers. Curiously, however, despite depleting GSH, ascorbate treatment diminished basal DNA damage and oxidative stress markers in TrxR1/Gsr-null livers. This suggests that, although ascorbate supplementation can prevent oxidative damage, it also can deplete GSH and compromise already stressed livers.

scholarly journals Revisiting summer infertility in the pig: could heat stress-induced sperm DNA damage negatively affect early embryo development?

2017 ◽  
Vol 57 (10) ◽  
pp. 1975 ◽  
Author(s):  
Santiago T. Peña, Jr ◽  
Bruce Gummow ◽  
Anthony J. Parker ◽  
Damien B. B. P. Paris
Keyword(s):  
Dna Damage ◽  
Heat Stress ◽  
Oxidative Damage ◽  
Unsaturated Fatty Acids ◽  
Negative Impact ◽  
Early Embryo ◽  
Antioxidant Systems ◽  
Sperm Dna Damage ◽  
Sperm Dna ◽  
Boar Sperm

Temperature is a crucial factor in mammalian spermatogenesis. The scrotum, pampiniform plexus, and cremaster and dartos muscles in mammals are specific adaptations to ensure sperm production in a regulated environment 4−6°C below internal body temperature. However, the limited endogenous antioxidant systems inherent in mammalian spermatozoa compounded by the loss of cytosolic repair mechanisms during spermatogenesis, make the DNA in these cells particularly vulnerable to oxidative damage. Boar sperm is likely to be more susceptible to the effects of heat stress and thus oxidative damage due to the relatively high unsaturated fatty acids in the plasma membrane, low antioxidant capacity in boar seminal plasma, and the boar’s non-pendulous scrotum. Heat stress has a significant negative impact on reproductive performance in piggeries, which manifests as summer infertility and results in productivity losses that amount to millions of dollars. This problem is particularly prevalent in tropical and subtropical regions where ambient temperatures rise beyond the animal’s zone of thermal comfort. Based on preliminary studies in the pig and other species, this article discusses whether heat stress could induce sufficient DNA damage in boar sperm to significantly contribute to the high rates of embryo loss and pregnancy failure observed in the sow during summer infertility. Heat stress-induced damage to sperm DNA can lead to disrupted expression of key developmental genes essential for the differentiation of early cell lineages, such as the trophectoderm, and can distort the timely formation of the blastocyst; resulting in a failure of implantation and ultimately pregnancy loss. Confirming such a link would prompt greater emphasis on boar management and strategies to mitigate summer infertility during periods of heat stress.

Protective role of thioredoxin reductase 1 in cadmium-induced DNA damage

2012 ◽  
Vol 8 (3) ◽  
pp. 289-295 ◽  
Author(s):  
Jee Yeon Park ◽  
Young Ju Lee ◽  
Preeyaporn Koedrith ◽  
Young Rok Seo
Keyword(s):  
Dna Damage ◽  
Thioredoxin Reductase ◽  
Protective Role ◽  
Thioredoxin Reductase 1

scholarly journals System-wide identification and prioritization of enzyme substrates by thermal analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Amir Ata Saei ◽  
Christian M. Beusch ◽  
Pierre Sabatier ◽  
Juan Astorga Wells ◽  
Hassan Gharibi ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Thioredoxin Reductase ◽  
Structural Level ◽  
Post Translational Modification ◽  
Post Translational Modifications ◽  
Enzyme Substrate ◽  
Thioredoxin Reductase 1 ◽  
Enzyme Substrates ◽  
Substrate Proteins

AbstractDespite the immense importance of enzyme–substrate reactions, there is a lack of general and unbiased tools for identifying and prioritizing substrate proteins that are modified by the enzyme on the structural level. Here we describe a high-throughput unbiased proteomics method called System-wide Identification and prioritization of Enzyme Substrates by Thermal Analysis (SIESTA). The approach assumes that the enzymatic post-translational modification of substrate proteins is likely to change their thermal stability. In our proof-of-concept studies, SIESTA successfully identifies several known and novel substrate candidates for selenoprotein thioredoxin reductase 1, protein kinase B (AKT1) and poly-(ADP-ribose) polymerase-10 systems. Wider application of SIESTA can enhance our understanding of the role of enzymes in homeostasis and disease, opening opportunities to investigate the effect of post-translational modifications on signal transduction and facilitate drug discovery.

scholarly journals Oxidative stress response in regulatory and conventional T cells: a comparison between patients with chronic coronary syndrome and healthy subjects

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Anna K. Lundberg ◽  
Rosanna W. S. Chung ◽  
Louise Zeijlon ◽  
Gustav Fernström ◽  
Lena Jonasson
Keyword(s):  
Oxidative Stress ◽  
T Cells ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Thioredoxin Reductase ◽  
Healthy Controls ◽  
Antioxidant Genes ◽  
Consistent Finding ◽  
Coronary Syndrome ◽  
Thioredoxin Reductase 1

Abstract Background Inflammation and oxidative stress form a vicious circle in atherosclerosis. Oxidative stress can have detrimental effects on T cells. A unique subset of CD4+ T cells, known as regulatory T (Treg) cells, has been associated with atheroprotective effects. Reduced numbers of Treg cells is a consistent finding in patients with chronic coronary syndrome (CCS). However, it is unclear to what extent these cells are sensitive to oxidative stress. In this pilot study, we tested the hypothesis that oxidative stress might be a potential contributor to the Treg cell deficit in CCS patients. Methods Thirty patients with CCS and 24 healthy controls were included. Treg (CD4+CD25+CD127−) and conventional T (CD4+CD25−, Tconv) cells were isolated and treated with increasing doses of H2O2. Intracellular ROS levels and cell death were measured after 2 and 18 h, respectively. The expression of antioxidant genes was measured in freshly isolated Treg and Tconv cells. Also, total antioxidant capacity (TAC) was measured in fresh peripheral blood mononuclear cells, and oxidized (ox) LDL/LDL ratios were determined in plasma. Results At all doses of H2O2, Treg cells accumulated more ROS and exhibited higher rates of death than their Tconv counterparts, p < 0.0001. Treg cells also expressed higher levels of antioxidant genes, including thioredoxin and thioredoxin reductase-1 (p < 0.0001), though without any differences between CCS patients and controls. Tconv cells from CCS patients were, on the other hand, more sensitive to oxidative stress ex vivo and expressed more thioredoxin reductase-1 than Tconv cells from controls, p < 0.05. Also, TAC levels were lower in patients, 0.97 vs 1.53 UAE/100 µg, p = 0.001, while oxLDL/LDL ratios were higher, 29 vs 22, p = 0.006. Conclusion Treg cells isolated from either CCS patients or healthy controls were all highly sensitive to oxidative stress ex vivo. There were signs of oxidant-antioxidant imbalance in CCS patients and we thus assume that oxidative stress may play a role in the reduction of Treg cells in vivo.

scholarly journals N-Acetylcysteine (NAC) for the Prevention of Liver Failure in Heat Injury-Mediated Ischemic Hepatitis

2019 ◽  
Vol 184 (9-10) ◽  
pp. 565-567 ◽  
Author(s):  
Joshua S Will ◽  
Christopher J Snyder ◽  
Katie L Westerfield
Keyword(s):  
Liver Failure ◽  
Heat Stroke ◽  
Altered Mental Status ◽  
Hemodynamic Instability ◽  
Laboratory Evaluation ◽  
Heat Injury ◽  
Us Army ◽  
Ischemic Hepatitis ◽  
Intravenous Hydration ◽  
Hepatocyte Necrosis

Abstract Exertional Heat Illness with associated ischemic hepatitis (IH) is a common occurrence among military trainees; however, few specific therapies exist if unresponsive to appropriate supportive measures. A 27-year-old basic combat trainee presented with altered mental status, renal insufficiency, rhabdomyolysis, and a core temp of 107.9 °F after collapsing during a run, leading to the diagnosis of heat stroke. While the patient’s azotemia and creatinine kinase levels rapidly improved with aggressive intravenous hydration, transaminases continued to increase to nearly 155 times the upper limit of normal. Further laboratory evaluation revealed coagulopathy and thrombocytopenia suggestive of acute liver failure (ALF). On hospital day three, the patient was started on N-acetylcysteine (NAC). Evaluation for infectious and autoimmune etiologies of ALF was unremarkable; thus, the patient’s symptomatology was attributed to IH resulting from heat stroke. Liver function normalized on NAC. Heat Injury is common among US Army recruits and results in thousands of hospitalizations in recent years. IH is characterized by diffuse hepatocyte necrosis following an episode of hemodynamic instability, and is an established sequela of Heat Injury. The mortality of IH among critically ill patients has been estimated to be as high as 60%, with those demonstrating coagulopathy especially at risk. NAC is shown to improve the transplant-free survival rate in non-acetaminophen related ALF, consistent with its proposed mechanisms of improving hepatic blood flow and conjugating toxic metabolites. NAC therapy should be considered early in the course of heat injury-mediated IH to reduce reperfusion injury, improving transplant free outcomes.

scholarly journals Antioxidant Activities and Selenogene Transcription in the European Sea Bass (Dicentrarchus labrax) Liver Depend, in a Non-linear Manner, on the Se/Hg Molar Ratio of the Feeds

2021 ◽  
Author(s):  
Marinelle Espino ◽  
Harkaitz Eguiraun ◽  
Oihane Diaz de Cerio ◽  
José Antonio Carrero ◽  
Nestor Etxebarria ◽  
...  
Keyword(s):  
Antioxidant Activities ◽  
Dicentrarchus Labrax ◽  
Thioredoxin Reductase ◽  
Sea Bass ◽  
Molar Ratio ◽  
Antioxidant Systems ◽  
European Sea Bass ◽  
Thioredoxin System ◽  
Non Linear ◽  
Linear Manner

AbstractFeeding 3.9 and 6.7 mg Hg/kg (Se/Hg molar ratios of 0.8 and 0.4, respectively) for 14 days negatively affected Dicentrarchus labrax growth and total DNTB- and thioredoxin-reductase (TrxR) activities and the transcription of four redox genes (txn1, gpx1, txnrd3, and txnrd2) in the liver, but a diet with 0.5 mg Hg/kg (Se/Hg molar ratio 6.6) slightly increased both reductase activities and the transcription of txn1, gpx1, and txnrd2. Feeding 6.7 mg Hg/kg for 53 days downregulated the genes of the thioredoxin system (txn1, txnrd3, and txnrd2) but upregulated gpx1, confirming the previously proposed complementarity among the antioxidant systems. Substitution of 20% of the feed by thawed white fish (hake) slightly counteracted the negative effects of Hg. The effects were not statistically significant and were dependent, in a non-linear manner, on the Se/Hg molar ratio of the feed but not on its Hg concentration. These results stress the need to consider the Se/Hg molar ratio of the feed/food when evaluating the toxicity of Hg.

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