Expair® testing kit

Context:

Ageing is an ineluctable biological process, characterised by a decline in physiological functions leading to morbidity and death.

Oxidation is the main cause of cellular ageing and age-related illnesses such as cancer, cardiovascular disorders, decline in immune function, brain dysfunction (Alzheimer's disease) and cataracts. This theory is supported by the fact that dietary antioxidants (ascorbic acid, tocopherols and carotenoids from fruit and vegetables) help prevent these degenerative diseases.

The oxidising agents are the reactive oxygen species (ROS) which include free radicals; having one or several lone electrons, these are very unstable atoms and molecules. They can be of both exogenous and endogenous origin (in the mitochondria). The main ROS are:

  • Singlet oxygen
  • Superoxide anion
  • Hydrogen peroxide
  • The OH radical
  • Nitric oxide NO
  • The hydroperoxy radicals that are produced during the peroxidation of membrane lipids, mainly those made from polyunsaturated fatty acids.

The damaging action of these ROS is called "oxidative stress". At the biochemical level, oxidative stress leads to:

  • Lipid peroxidation which targets cell and mitochondrial membranes. The polyunsaturated fatty acids (PUFAs) are attacked and release ethane (w-3 PUFAs) and pentane (w-6 PUFAs).
  • Oxidation of mitochondrial proteins which leads to respiratory chain disorders and a decrease in cellular energy production.
  • Mitochondrial DNA oxidation (DNAmt) which induces mitochondrial mutations and dysfunction.

The production of these ROS is related to:

* Normal endogenous biochemical mechanisms, in particular the respiratory chain: 2% to 4% of the oxygen involved is incompletely reduced and gives rise to ROS.

* Exogenous stress factors such as:

- Inflammatory diseases
- Solar irradiation or ionising radiation
- Smoking
- Pollution
- Allergies
- Prolonged effort

In the case of prolonged effort, for example, the oxygen demand (and thus consummation) increases, inducing both a state of hypoxia and an over-production of ROS.

Assessment of oxidative stress

As mentioned earlier, oxidative stress causes metabolic disorders including lipid peroxidation which leads to the formation of ethane and pentane. These products are gases which are then eliminated in the expired air.

Ethane and pentane are thus biomarkers of oxidative stress. In this respect, some authors consider pentane to be more significant than ethane in vivo since w-6 PUFAs predominate over w-3 PUFAs as structural lipids of the membrane.

The concentration of ethane/pentane measured in the expired air is proportional to the state of oxidative stress.

These biomarkers have been described by a number of authors and are now well-recognised .

The concentration of ethane/pentane measured in the expired air is proportional to the state of oxidative stress.

La concentration mesurée en éthane/pentane dans l'air expiré est proportionnelle à l'état de stress oxydatif.

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