In solid cancer surgery, oxidative stress (OS) is of particular interest because both the malignancy itself and the surgical intervention are major contributors to the modulation of OS levels. This study aimed to investigate the effects of solid cancer surgery on OS levels. Because solid cancer is often accompanied by intense cell death, the study specifically focused on the pathway leading to uric acid formation, (i.e. adenosine deaminase (ADA) and xanthine oxidase (XO). Ische-mia-modified albumin (IMA), a recognized marker of oxidative stress, and plasma redox poten-tial (RP) were also measured. Thirty-six patients undergoing major solid cancer surgery (median age 68 years (58-76), 23 men and 13 women) and thirty controls (62 years (51-80)) were included. During the surgical procedure, serum ADA levels did not change significantly (10.4 International Units (IU) (6.9 – 13.7) vs. 8 IU (6 – 12); p = 0.47). In contrast, XO (IU), IMA (Arbitrary Units(AU)) and redox potential (mV) decreased significantly (22.5 IU (11 – 63) vs. 8.4 IU (5 – 27); p = 0.0041, 89 AU (69 – 105) vs. 74 AU (66 – 80); p = 0.01 and 98 mV (78 – 118) vs. 79 mV (65 – 101); p = 0.033). The correlation between XO and IMA or redox potential was positive (Spearman’s r = 0.32 ; p = 0.007, and r = 0.58; p < 0.001, respectively). XO was negatively correlated with ADA (r = -0.26; p = 0.03). Redox potential was positively correlated with IMA (r = 0.26; p = 0.04) and nega-tively correlated with ADA (r = -0.25 ;p = 0.04). We found that a major source of OS in solid cancer could be the result of an increase in xanthine oxidase activity and that the global effect of solid cancer surgery is a significant decrease in OS levels. We also found that ADA and XO were inversely correlate, suggesting the existence of a negative retrocontrol between the production of free radicals and the production of their sub-strate. Finally, our study highlights the potential value of XO inhibitors as adjuvant therapy in solid tumor surgery.

Decompression sickness (DCS) with neurological disorders is the leading cause of diving accidents. Exposure to high levels of CO2 during diving is a safety concern for occupational , groups at risk of DCS. However, the effects of prior exposure to CO2 have never been evaluated. The purpose of this study was to evaluate the effect of CO2 breathing prior to a provocative dive on the occurrence of DCS in mice. 50 mice were exposed to a maximum CO2 concentration of 70 hPa for one hour at atmospheric pressure. Another 50 mice breathing air under similar conditions served as controls. In the AIR group (controls), 22 out of 50 mice showed post-dive symptoms compared to 44 out of 50 in the CO2 group. We found that CO2 breathing is associated with a decrease in body temperature in mice and that CO2 exposure dramatically increases the incidence of DCS. More unexpectedly, it appears that a lower temperature of the animals even before exposure to the accident-prone protocol leads to an unfavorable prognosis. This study also suggests that the composition of the microbiota may influence thermogenesis and thus accidentology. Depending on prior exposure, some bacteria identified in this work could be perceived as protective or pathogenic.