Selenium, selenoprotein P, and oxidative stress levels in SARS-CoV-2 patients during illness and recovery.

BACKGROUND: This study aimed to assess tendency of oxidative stress in COVID-19 patients depending on severity. METHODS: The study was conducted with 80 post-COVID-19 disease patients and 40 acutely ill patients. Content of selenium in blood plasma was detected by a fluorimetric method with di-amino-naphthalene using acidic hydrolysis. Selenoprotein P, malondialdehyde and 4-hydroxynonenal and their metabolite adducts were evaluated by spectrophotometric methods using commercial assay kits. RESULTS: Obtained results showed that selenium content in blood for post-COVID-19 disease patients was of a similar lower norm for Latvian inhabitants. Selenium and seleno-protein P contents for acute patients were significantly decreased compared with post-COVID-19 disease patients. CONCLUSION: In conclusion, COVID-19 involves induction of antioxidant systems-in case of severe disease, patients have significantly low concentration of selenium, seleno-protein P and higher level of oxidative stress, which, in turn, confirms the more intense formation of free radicals in the body.

Biochemical observations relating to oxidant stress injury in Chernobyl clean-up workers ("liquidators") from Latvia.

AIMS: To establish if there is further evidence for the long-term oxidant stress injury (as reported previously--Kumerova et al. in Biol Trace Elem Res 77:1-12, 2000) in surviving Chernobyl nuclear power plant (NPP) workers from Latvia. The overall objectives of this study have been to establish if there have been long-term systemic changes in the oxidant/antioxidant status of clean-up workers that might reflect adaptation to the progression of oxidative stress injury. METHODS: Biochemical analyses of the circulating levels of endogenous oxidants and anti-oxidants were undertaken over two periods (Stage 1 in 1998-1999 and Stage 2 in 2005-2006) at approximately 6-7 years time interval, in order to establish if there have been time-dependent changes in the parameters that may be important for the health of the clean-up workers. The biochemical analyses included (a) plasma levels of the anti-oxidant, selenium, (b) blood and plasma levels of glutathione peroxidase, (c) red blood cell catalase, (d) plasma total oxidant status as lipid peroxides and hydroperoxides, (e) plasma ceruloplasmin, and (f) total blood levels of zinc and copper. RESULTS: The circulating content of lipid peroxides, plasma oxidisability, lipid peroxides, catalase, Zn, and Cu were elevated above normal values at both the stages of this study. Glutathione peroxidase was increased above normal values at Stage 1 but not at Stage 2. The most pronounced changes between Stage 1 and Stage 2 were (a) a reduction by about (1/2) in the content of lipid peroxides and lipid peroxidation, but not in the blood oxidisability and (b) increased plasma selenium. The data show that there may be a partial improvement in the anti-oxidant/oxidant status of the Chernobyl NPP workers over the 7-year period of investigation. CONCLUSIONS: The NPP patients may be undergoing progressive reduction in blood oxidants accompanied by adaptation to oxidant stress injury due to the increased anti-oxidant activity measured in their plasma and blood.

Antioxidant defense and trace element imbalance in patients with postradiation syndrome: first report on phase I studies.

More than 6000 residents of Latvia were involved in recovery work in Chernobyl. They were healthy men exposed to substantial ionizing radiation (0.01-0.5 Gy). Now, these recovery workers suffer from "postradiation syndrome": dizziness and poor memory, headache, local pains, and so forth. The biochemical mechanism of "postradiation syndrome" has not been completely established. In this Phase I study, we have investigated how exposure to radiation impacts antioxidative defense and trace element concentrations in the blood of recovery workers. Thirty-five patients with postradiation syndrome (men, age range 33-50 yr) and 15 healthy men similar in age as control subjects were studied for the effects on plasma chemiluminescence, the activity of antioxidant enzymes, and the concentration of ceruloplasmin and concentrations of selenium (Se), zinc (Zn), and copper (Cu) in blood. The results revealed that plasma chemiluminescence was significantly increased (3.5-fold to 5.5-fold), the activity of catalase in erythrocytes was significantly elevated, and the activity of glutathione peroxidase in plasma was significantly reduced in examined patients. Concentrations of Zn and Cu were significantly higher and the concentration of Se was lower in these patients. We conclude that the patients exposed to ionizing radiation have diminished blood antioxidant defense associated with pronounced Se deficiency and imbalance of Zn and Cu.

Anaemia and antioxidant defence of the red blood cells.

Antioxidant defence was investigated in red blood cells (RBC) in 56 patients with 3 different haemoblastoses: polycythemia vera (PV), chronic myelogenous leukaemia (CML), chronic lymphoid leukemia (CLL) with and without anaemia, in 12 iron deficiency anaemia (A) patients and 50 healthy persons. The activities were determined of the following antioxidant enzymes: glucose-6-phosphate dehydrogenase (G6PD), glutathione reductase (GSSG-R), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT) and MDA levels. Antioxidant defence is decreased and the level of lipid peroxidation are increased in RBC in all patients (PV, CML, CLL, A). Different changes were detected in the antioxidative defence between normal red blood cells and those formed from leukaemic cells clone. In normal RBC in anaemia (CLL, A) opposite deviation of G6PD and GSSG-R activities was observed. In RBC formed from leukaemic cell clone (PV, CML), a simultaneous significant increase in G6PD and GSSG-R activities was found, which indicated activisation of pentose phosphate pathways (PPP) in these pathologies; in anaemia they function less effectively.

The activity of glucose-6-phosphate dehydroxygenase and glutathione enzymes in red blood cells in patients with haemoblastoses.

The activity of glucose-6-phosphate dehydrogenase (G6PD), glutathione reductase (GSSG-R), glutathione peroxidase (GSH-Px) and MDA levels have been assayed in red blood cells (RBC), obtained from 57 people suffering from haemoblastoses. The activities of G6PD in the RBC in patients with polycythemia vera (PV) and chronic lymphoid leukemia (CML) are significantly higher than those in healthy patients. Changes in the activity of glutathione dependent enzymes GSSG-R and those of GSH-Px in the RBC go in opposite directions: the activity of GSSG-R is significantly enhanced in patients with PV and CML, but the activity of GSH-Px is decreased in all patients suffering from haemoblastoses. The high levels of MDA in the RBC of all patients with haemoblastoses indicate intensification of lipid peroxidation in their RBC.