Monitoring antioxidant defenses and free radical production in space-flight, aviation and railway engine operators, for the prevention and treatment of oxidative stress, immunological impairment, and pre-mature cell aging.

Degenerative diseases, immune impairment, and premature ageing commonly affect professional categories exposed to severe environmental and psychological stress. Among these, cosmonauts routinely experience extreme conditions due to microgravity, space radiation, altered oxygen supply, physical and mental fatigue during training, spaceflight, and post-flight. Long route aviation pilots display elevated oncogenic risk, connected with cosmic radiation overexposure, and high mortality rates for cardiovascular causes. Engine drivers, like pilots, are affected by health consequences of psycho-emotional stress, and burnout syndrome. The free radical (FR)/antioxidant (AO) imbalance is a common feature in all these pathological conditions. To assess the effective relevance of oxidative stress, we analyzed blood and urine reliable markers of FR production and AO defenses in 12 Russian cosmonauts, 55 airline pilots, 63 train engine drivers, and 50 age-matched controls by measuring the following: (a) lipophilic/hydrophilic low-molecular weight AO and AO enzyme activities, (b) nitric oxide, superoxide anion, hydroperoxide production, and (c) urinary catecholamine/serotonine metabolites and lipoperoxidation markers. Cosmonauts showed elevated granulocyte superoxide and nitric oxide production, increased erythrocyte superoxide dismutase activity and glutathione oxidation, and drastically decreased plasma/leucocyte lipophilic AO levels (P < 0.001-0.01). Aviation pilots, like train drivers, displayed a mild but constant oxidative stress, more pronounced in intercontinental routes pilots, and consistent with lymphocyte chromosomal alterations, DNA oxidation, and cardiovascular malfunction. Results obtained on these selected professionals operating under wearing conditions offer a solid molecular basis for advising the regular monitoring of clinical biochemistry laboratory markers of AO/FR status, to tailor individually specific AO supplementation and diet regimen, and monitor treatment outcomes.