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  • Author: Osman Yildirim x
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Background: Studies with single-session hyperbaric oxygen exposures have shown that HBO-induced oxidative stress is proportional to exposure pressure and duration. Since the efficacy of hyperbaric oxygen mainly depends on repetitive exposures, this study aimed to investigate the oxidative effect of hyperbaric oxygen administered for 5 to 40 sessions.

Methods: Sixty rats were divided into one control and 6 study groups. Study groups were exposed to 5, 10, 15, 20, 30, and 40 daily consecutive 2.8 atm/90 min hyperbaric oxygen sessions. Animals were sacrificed 24 h after the last hyperbaric oxygen administration. Malondialdehyde and carbonylated protein levels as well as superoxide dismutase activities were determined in isolated rat erythrocytes.

Results: Carbonylated protein levels increased significantly after just 5 hyperbaric oxygen exposures; reached a peak level with 10 exposures; were still significantly higher than controls after 15 sessions; and decreased to normal limits after 20 exposures. Malondialdehyde levels were found to be significantly increased in the 10 to 30, but not in the 5 and 40-session groups. Superoxide dismutase activity showed elevated levels only in the 5 and 10 times hyperbarical oxygen-exposed groups.

Conclusions: The suppressed oxidative stress level after 40 exposures suggests an effective endogenous antioxidant defense in repetitive HBO administrations.


This article introduces a step-by-step methodology for evaluating an enterprise’s investment attractiveness in the context of economic development, using appropriate valuation parameters at macro, meso and micro levels. A system of indicators of macro-level investment attractiveness has been formed based on the criteria of socio-economic and legal attractiveness and investment risks. The indicators for assessing investment attractiveness of the industry have been grouped by the criteria of: prospects of the industry, positioning of the enterprise in the industry market, and sectoral investment risks. The indicators of investment attractiveness have been systematised with the use of three-dimensional current and operational analysis, as well as the method of risk assessment, which helped to determine the area of reaction to risk zones of the enterprise’s investment potential. The research allowed us to assess the position of a company in the market and to predict the risks of investing in the chemical industry.