Biomedical subjects

O Tirosh

Publications and source records attributed to O Tirosh.

21 records · Page 2Linked to original sources

PubMed1992

The reductive capacity index of saliva obtained from donors of various ages.

The reducing ability of saliva is decreased with donor age as indicated by cyclic voltammetry measurements of saliva. It has been shown that saliva possesses a strong reducing power that is influenced by the induction of oxidative stress. The exact capacity of saliva to cope with oxidative stress has never been studied in detail. We used a new approach to detect the role of oxidative stress on saliva. This approach included the detection of the total reducing capacity of the saliva without determination of the exact concentration of a specific reducing compound present in the saliva. Induction of oxidative stress resulted in a significant change in the reductive capacity detected. Measurements of the reducing potential of saliva revealed that there is a correlation between the donor age and the reductive capacity observed. Also, saliva obtained from donors in various disease states have shown a significant change in the potential recorded, as compared to controls. The possible use of this method as a diagnostic tool in various diseases is discussed.

Adolescent↗

PubMed1992

The biological reductive capacity of tissues is decreased following exposure to oxidative stress: a cyclic voltammetry study of irradiated rats.

The reductive capacity of rat tissue homogenates and body fluids was determined by cyclic voltammetric measurements. The reductive capacity of rat lung, liver and kidney homogenates was significantly reduced four days after total body gamma-ray irradiation with 5.5 Gy as compared to controls. In parallel, reduced ability of the irradiated organ homogenates to scavenge hydroxyl radicals and to destroy hydrogen peroxide was recorded. However, no difference in their superoxide dismutase activity was found. The possible use of cyclic voltammetry as a method for qualitative evaluation of the ability of biological tissues to cope with oxidative stress is discussed.

Animals↗

PubMedDate not supplied

Reducing equivalents in the aging process.

Reducing equivalents may play a major role in the aging process. These metabolites are responsible for the endogenous redox potential in the living cell which is kept under tight regulation. Among their various roles is the ability to donate electrons to reactive oxygen species and by doing so to scavenge them. Most of the reducing equivalents in the cell are molecules with low molecular weights, such as glutathione and NADH which are synthesized by the cell. Other members of this group, such as uric acid are produced as waste products, while others, such as ascorbic acid and tocopherol, are derived from the diet. We studied the role of these equivalents in the aging process in various rat tissues. We demonstrated that the reducing power of a tissue may reflect its antioxidant activity. We used cyclic voltammeter methodology in order to evaluate the overall reducing power of tissue homogenates and other biological fluids. It was found that reducing power changes during the aging process in a bell-shaped manner in liver, lungs and kidneys, but not in heart and brain. We also showed that skin possesses strong reducing power which decreases dramatically with age. A non-invasive procedure to evaluate the oxidation status and the antioxidant activity of skin was developed. Using this method we demonstrated that there is an accumulation of organic peroxide in old skin compared to young skin, supporting the free radical hypothesis of aging.

Journal Article↗