Lipid peroxidation and antioxidant enzyme activities in erythrocytes of type I and II alcoholics

The Status of Oxidative Stress in Patients with Alcohol Dependence: A Meta-Analysis

Alcohol-induced oxidative stress (OS) plays a pivotal role in the pathophysiology of alcohol dependence (AD). This meta-analysis was aimed at investigating the changes in the levels of OS biomarkers in AD patients. We included relevant literature published before 1 April 2022, from the PubMed, Web of Science, and EBSCO databases following PRISMA guidelines. Finally, 15 eligible articles were enrolled in this meta-analysis, including 860 patients and 849 controls. Compared with healthy controls, AD patients had lower activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzymes, and lower levels of albumin, while levels of malondialdehyde (MDA), vitamin B12, homocysteine, and bilirubin were significantly increased in serum/plasma samples of AD subjects (all p < 0.05). In male patients, the activities of SOD and GPx were increased in serum/plasma but decreased in erythrocytes (all p < 0.05). The opposite trends in the level of SOD and GPx activities in serum/plasma and erythrocytes of male patients could be used as the biomarker of alcohol-induced OS injury, and the synergistic changes of MDA, vitamin B12, albumin, bilirubin, and homocysteine levels should also be considered.

Glutathione and Transsulfuration in Alcohol-Associated Tissue Injury and Carcinogenesis

Glutathione (GSH) is the most abundant non-protein thiol, attaining cellular concentrations in the millimolar range. GSH functions to protect cells against endogenous and exogenous electrophiles. In addition, GSH serves as a cofactor for the GSH peroxidase family of enzymes which metabolize H₂O₂ as well as lipid peroxides. Through the action of glutathione S-transferase family of enzymes, GSH is conjugated to a variety of electrophilic endogenous compounds and exogenous chemicals, and thereby facilitates their efficient and safe elimination. Through the transsulfuration pathway, GSH biosynthesis is metabolically linked with cellular methylation, which is pivotal for epigenetic gene regulation. Accumulating evidence suggests that the underlying mechanisms of alcohol-associated tissue injury and carcinogenesis involve: (i) generation of the electrophilic metabolite acetaldehyde, (ii) induction of CYP2E1 leading to the formation of reactive oxygen species and pro-carcinogen activation, and (iii) nutritional deficiencies, such as methyl groups, resulting in enhanced susceptibility to cancer development. In this context, clinical and experimental investigations suggest an intimate involvement of GSH and related enzymes in the development of alcohol-induced pathological conditions. The aim of this review is to provide an overview of the GSH biosynthesis, cellular transsulfuration/transmethylation pathways, and their implications in the pathogenesis and treatment of alcohol-related disease and cancer.

The osmotic resistance, and zeta potential responses of human erythrocytes to transmembrane modification of Ca2+ fluxes in the presence of the imposed low rate radiation field of 90Sr

PURPOSE

To investigate the effects of the imposed low dose rate ionizing field on membrane stability of human erythrocytes under modulation of transmembrane exchange of Ca(2+).

MATERIALS AND METHODS

Osmotic resistance of human erythrocytes was determined by a measure of haemoglobin released from erythrocytes when placed in a medium containing serial dilutions of Krebs isotonic buffer. The zeta potential as indicator of surface membrane potential was calculated from value of the cellular electrophoretic mobility. The irradiation of erythrocyte suspensions carried out by applying suitable aliquots of (90)Sr in incubation media.

RESULTS

Irradiation of human erythrocytes by (90)Sr (1.5-15.0 μGy·h(-1)) induced a reversible increase of hyposmotic hemolysis and negative charge value on the outer membrane surface as well as changed responses these parameters to modification of Ca(2+) fluxes with calcimycin and nitrendipine.

CONCLUSIONS

Findings indicate that the low dose rate radionuclides ((90)Sr) field modifies both Ca(2+)-mediated, and Ca(2+)-independent cellular signalling regulating mechanical stability of erythrocyte membrane. A direction of that modification presumably depends on the initial structure of membranes, and it is determined by the quality and quantitative parameters of changes in membrane structure caused by concrete operable factors.

Oxidative damage in young alcohol drinkers: A preliminary study

BACKGROUND

Oxidative damage (OD) biomarkers have been used to evaluate metabolic stress undergone by alcoholic individuals. In alcoholic patients, these biomarkers are usually measured at late stages, i.e., when the alcoholic patients are showing clear signs of impaired hepatic function. OD biomarkers are sensitive indicators of impaired metabolic function, and might be useful in early stages of alcohol consumption to identify individuals who are at greater risk of damage in later stages of alcohol consumption. The aim of the present work was to evaluate some OD biomarkers in young people at early stages of alcohol consumption.

METHODS

The study was carried out in a group of young people (18-23 years old) who drank alcohol, Youngsters Exposed to Alcohol (YEA) with an average intake of 118 g of ethanol/week, and a control group (CG) of non-drinkers. Blood counts, alcohol dehydrogenase (ADH) activity, glutathione peroxidase (GSH-Px) activity, oxidative damage to DNA, and lipid peroxidation were determined in both groups.

RESULTS

The anthropometric and blood parameters of both groups were similar and no clinical symptoms of hepatic damage were observed. Nevertheless, ADH activity, lipid peroxidation, and percentage of damaged DNA cells were higher in the YEA group than in the control group. In contrast, GSH-Px activity was lower in the YEA group than in the control group.

CONCLUSION

Alteration in OD biomarkers can be found in individuals with 4-5 years of alcohol drinking history. To our knowledge, this is the first study giving evidence of OD in individuals at early stages of alcohol abuse.

Influence of green tea on erythrocytes antioxidant status of different age rats intoxicated with ethanol

The aim of this paper is to evaluate the effect of green tea on the erythrocyte antioxidant system of ethanol-intoxicated rats, as well as its efficacy in the prevention of lipid peroxidation. Rats (2, 12 and 24 months old) were fed on a control or an ethanol Lieber-DeCarli diet with and without green tea (7 g/L) for 5 weeks. Examination included the activity of antioxidant enzymes and the level of both non-enzymatic antioxidants and lipid peroxidation marker in rat erythrocytes. It was shown that ageing was accompanied by changes in the antioxidant enzymes activity - increase in the SOD and CAT activity and decrease in GSSG-R and GSH-Px activity, as well as in the level of non-enzymatic antioxidants - GSH, vitamin A and vitamin E. The increase in the level of lipid peroxidation marker - MDA - was also observed. Green tea consumption partially prevented lipid peroxidation process, especially in erythrocytes of 2- and 12-month-old rats. It was proved that ethanol administration caused a statistically significant decrease in the activity/level of the examined antioxidants in all age groups (the most significant in the case of 24-month-old rats) of rats, as well as an increase in the MDA level. However, ingestion of green tea by ethanol-intoxicated rats partially prevented the decrease in activity/level of all examined antioxidant parameters, as well as protected lipids against peroxidation in all age groups of rats. Obtained results confirm the beneficial effect of green tea on erythrocyte antioxidant abilities.

Glutathione level after long-term occupational elemental mercury exposure

Many in vitro and in vivo studies have elucidated the interaction of inorganic mercury (Hg) and glutathione. However, human studies are limited. In this study, we investigated the potential effects of remote long-term intermittent occupational elemental Hg vapour (Hg degrees ) exposure on erythrocyte glutathione levels and some antioxidative enzyme activities in ex-mercury miners in the period after exposure. The study included 49 ex-mercury miners divided into subgroups of 28 still active, Hg degrees -not-exposed miners and 21 elderly retired miners, and 41 controls, age-matched to the miners subgroup. The control workers were taken from "mercury-free works". Reduced glutathione (GSH) and oxidized disulphide glutathione (GSSG) concentrations in haemolysed erythrocytes were determined by capillary electrophoresis, while total glutathione (total GSH) and the GSH/GSSG ratio were calculated from the determined values. Catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) activities in erythrocytes were measured using commercially available reagent kits, while urine Hg (U-Hg) concentrations were determined by cold vapour atomic absorption (CVAAS). No correlation of present U-Hg levels, GSH, GSSG, and antioxidative enzymes with remote occupational biological exposure indices were found. The mean CAT activity in miners and retired miners was significantly higher (p<0.05) than in the controls. No differences in mean GPx activity among the three groups were found, whereas the mean GR activity was significantly higher (p<0.05) in miners than in retired miners. The mean concentrations of GSH (mmol/g Hb) in miners (13.03+/-3.71) were significantly higher (p<0.05) than in the control group (11.68+/-2.66). No differences in mean total GSH, GSSG levels, and GSH/GSSG ratio between miners and controls were found. A positive correlation between GSSG and present U-Hg excretion (r=0.41, p=0.001) in the whole group of ex-mercury miners was observed. The significantly lower GSH level (p<0.05) determined in the group of retired miners (9.64+/-1.45) seems to be age-related (r= -0.39, p=0.001). Thus, the moderate but significantly increased GSH level, GR and CAT activity in erythrocytes in the subgroup of miners observed in the period after exposure to Hg degrees could be an inductive and additive response to maintain the balance between GSH and antioxidative enzymes in interaction with the Hg body burden accumulated during remote occupational exposure, which does not represent a severely increased oxidative stress.