Lipid peroxides as endogenous oxidants forming 8-oxo-guanosine and lipid-soluble antioxidants as suppressing agents

Oxidative guanine base damage plays a dual role in regulating productive ALT-associated homology-directed repair

Cancer cells maintain telomeres by upregulating telomerase or alternative lengthening of telomeres (ALT) via homology-directed repair at telomeric DNA breaks. 8-Oxoguanine (8oxoG) is a highly prevalent endogenous DNA lesion in telomeric sequences, altering telomere structure and telomerase activity, but its impact on ALT is unclear. Here, we demonstrate that targeted 8oxoG formation at telomeres stimulates ALT activity and homologous recombination specifically in ALT cancer cells. Mechanistically, an acute 8oxoG induction increases replication stress, as evidenced by increased telomere fragility and ATR kinase activation at ALT telomeres. Furthermore, ALT cells are more sensitive to chronic telomeric 8oxoG damage than telomerase-positive cancer cells, consistent with increased 8oxoG-induced replication stress. However, telomeric 8oxoG production in G2 phase, when ALT telomere elongation occurs, impairs telomeric DNA synthesis. Our study demonstrates that a common oxidative base lesion has a dual role in regulating ALT depending on when the damage arises in the cell cycle.

Effect of Deletions of the Genes Encoding Pho3p and Bgl2p on Polyphosphate Level, Stress Adaptation, and Attachments of These Proteins to Saccharomyces cerevisiae Cell Wall

Inorganic polyphosphates (polyP), according to literature data, are involved in the regulatory processes of molecular complex of the Saccharomyces cerevisiae cell wall (CW). The aim of the work was to reveal relationship between polyP, acid phosphatase Pho3p, and the major CW protein, glucanosyltransglycosylase Bgl2p, which is the main glucan-remodelling enzyme with amyloid properties. It has been shown that the yeast cells with deletion of the PHO3 gene contain more high molecular alkali-soluble polyP and are also more resistant to exposure to alkali and manganese ions compared to the wild type strain. This suggests that Pho3p is responsible for hydrolysis of the high molecular polyP on the surface of yeast cells, and these polyP belong to the stress resistance factors. The S. cerevisiae strain with deletion of the BGL2 gene is similar to the Δpho3 strain both in the level of high molecular alkali-soluble polyP and in the increased resistance to alkali and manganese. Comparative analysis of the CW proteins demonstrated correlation between the extractability of the acid phosphatase and Bgl2p, and also revealed a change in the mode of Bgl2p attachment to the CW of the strain lacking Pho3p. It has been suggested that Bgl2p and Pho3p are able to form a metabolon or its parts that connects biogenesis of the main structural polymer of the CW, glucan, and catabolism of an important regulatory polymer, polyphosphates.

The snapshot of metabolic health in evaluating micronutrient status, the risk of infection and clinical outcome of COVID-19

COVID-19 has re-established the significance of analyzing the organism through a metabolic perspective to uncover the dynamic interconnections within the biological systems. The role of micronutrient status and metabolic health emerge as pivotal in COVID-19 pathogenesis and the immune system's response. Metabolic disruption, proceeding from modifiable factors, has been proposed as a significant risk factor accounting for infection susceptibility, disease severity and risk for post-COVID complications. Metabolomics, the comprehensive study and quantification of intermediates and products of metabolism, is a rapidly evolving field and a novel tool in biomarker discovery. In this article, we propose that leveraging insulin resistance biomarkers along with biomarkers of micronutrient deficiencies, will allow for a diagnostic window and provide functional therapeutic targets. Specifically, metabolomics can be applied as: a. At-home test to assess the risk of infection and propose nutritional support, b. A screening tool for high-risk COVID-19 patients to develop serious illness during hospital admission and prioritize medical support, c(i). A tool to match nutritional support with specific nutrient requirements for mildly ill patients to reduce the risk for hospitalization, and c(ii). for critically ill patients to reduce recovery time and risk of post-COVID complications, d. At-home test to monitor metabolic health and reduce post-COVID symptomatology. Metabolic rewiring offers potential virtues towards disease prevention, dissection of high-risk patients, taking actionable therapeutic measures, as well as shielding against post-COVID syndrome.

The effect of different tobacco tar levels on DNA damage in cigarette smoking subjects

Objective

To explore the genetic damage caused by different tar levels in the human body.

Methods

The subjects were divided into high, medium and low (12 mg, 8 mg, 5 mg) tar groups according to the tar levels. Nonsmoking populations served as a control group. 2 ml of peripheral blood was collected on the 10th day after morning fasting. Oxidative and genetic toxicological damage indicators were analysed with enzyme-linked immunosorbent assay, cytokinesis-block micronucleus assay in human lymphocyte and single cell gel electrophoresis.

Results

The distribution of hOGG1 concentration was significantly different within all groups, P < 0.01. The concentrations of cotinine, 8-OHdG and Rap-2b were significantly differences between control and medium tar group, control and high tar group, low and medium tar group and low and high tar group, respectively, P < 0.05. The level of PAH-DNA adducts was not significantly changed in the middle tar group and high tar group, P > 0.05. The level of CRP was significantly changed between control and high tar group, low and high tar group and medium and high tar group, respectively, P < 0.0001. The rate of comet tailing was significantly different between all groups. The rate of micronucleus cells was not significantly different between all groups.

Conclusions

The increase of tar content could increase the DNA damage to a certain extent, so the intake of tar content should be monitored.

Oxidative Stress and Inflammation in Early Onset First Episode Psychosis: A Systematic Review and Meta-Analysis

Background

People with schizophrenia and other psychosis show increased proinflammatory and prooxidative status. However, the few studies that have specifically assessed oxidative and inflammatory markers in early onset psychosis (onset before age 18) have shown contradictory results.

Methods

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines for systematic reviews and meta-analyses were used to conduct a systematic literature search to detect studies comparing inflammatory and oxidative markers in early onset psychosis patients and healthy controls.

Results

Seven studies met criteria for the qualitative analysis. Four studies met criteria for meta-analysis, comprising an overall sample of 261 early onset psychosis patients and 246 healthy controls. Six independent meta-analyses were performed for catalase, glutathione, glutathione peroxidase, superoxide dismutase, total antioxidant status, and cell/DNA oxidative damage. No significant differences were found between early onset psychosis patients and controls in any of the parameters assessed. Heterogeneity among studies was high. Qualitative analysis of individual studies showed an association of inflammatory and oxidative markers with clinical, cognitive, and neurobiological outcomes, especially in longitudinal assessments.

Conclusions

Despite the lack of significant differences between early onset psychosis patients and controls in the oxidative markers assessed in the meta-analyses, results based on individual studies suggest that greater inflammation and oxidative stress might lead to poorer outcomes in patients with first episodes of early onset psychosis.