réactions du Tunisien aux agressions des oxydants

je ne parle pas de l'occident mais des oxydants ou encore de façon plus correcte des radicaux libres(ROS (Reactive oxygen species))    dont l'histoire n'a pas encore fait l'effet dans notre société alors que  dans les autres pays civilisés des programmes de lutte sont mise en place pour réduire leur effets néfastes. ils sont responsables de la vieillesse et de la majorité des maladies graves, ils sont produits en plus grands nombre en cas de tabagisme , en cas de pollution,en cas de radiation, lors d’excès de consommation d'alcool, ou lors d'exposition aux métaux lourds, les exercices physiques excessifs surtout pour les personnes non adaptées aux efforts,  l'état de stress les hormones telles les catécholamines participent à la formation de quantité importante de ROS, nous fabriquons régulièrement des radicaux libres mais nous consommons des antidotes qui sont les anti-oxydants, il faut connaitre ces produits pour pouvoir lutter contre les radicaux libres et éviter autant que possible leurs effets nocifs.

(Scientists from the ARC Centre of Excellence for Free Radical Chemistry and Biotechnology

at The Australian National University have discovered a unique natural defence mechanism against ageing. The team, led by Professor Chris Easton from the Free Radical Centre at ANU, have discovered that amino acids are working hard to protect our bodies from the ageing process caused by being exposed to free radicals and oxygen. Free radicals and other oxidative species are well known to contribute to ageing, and are linked to many common diseases such as cancers, heart disease and neurodegenerative diseases.“We have found that amino acids are remarkably resistant to damage by free radicals and oxygen,” reveals Professor Easton. “What many people don’t realise is that just by breathing in oxygen we are exposing our bodies to free radicals and oxidative stress which leads to ageing. But of course we need to breathe to stay alive, so it is one of the great paradoxes of life ) 

les exercices physiques ne semblent pas endommager les tissus des sportifs réguliers malgré une formation de radicaux libres de façon excessive, ceci semble être en relation avec les système de défense utilisant plus d'anti-oxydants.

(Exercise and oxidative damage

Endurance exercise can increase oxygen utilization from 10 to 20 times over the resting state. This greatly increases the generation of free radicals, prompting concern about enhanced damage to muscles, and other tissues. As it is not possible to directly measure free radicals in the body, the by-products that result from free radical reactions can be measured. If the generation of free radicals exceeds the antioxidant defenses then one would expect to see more of these by-products. Regular  physical exercise enhances the antioxidant defense system and protects against exercise induced free radical damage. These changes occur slowly over time and appear to parallel other adaptations to exercise. On the other hand, intense exercise in untrained individuals  overwhelms defenses resulting in increased free radical damage. Thus, the "weekend warrior" who is predominantly sedentary during the week but engages in vigorous bouts of exercise during the weekend may be

doing more harm than good)
les ROS  ou les radicaux libres sont la cause de la majorité des maladies dégénératives:

(Abheri Das Sarma et. al. / International Journal of Pharma Sciences and Research (IJPSR)

Vol.1(3), 2010, 185-192)

Cancer:

Like radiation and carcinogens, free-radical oxidation breaks strands of DNA. The breaks are repaired,but some mistakes occurs leading mutations. These genetic mutations can cause cancers. The age-related increase in cancer rates might have something to do with an age-related rise in oxidative damage to DNA.

Alzheimer’s disease:

The brain in Alzheimer's disease (AD) is under increased oxidative stress and this may have a role in the pathogenesis of neuron degeneration and death in this disorder. The direct evidence supporting

increased oxidative stress in AD is: (1) increased brain Fe, Al, and Hg in AD, capable of stimulating free radical generation; (2) increased lipid peroxidation and decreased polyunsaturated fatty acids in the AD brain, and increased 4-hydroxynonenal, an aldehyde product of lipid peroxidation in AD ventricular fluid; (3) increased protein and DNA oxidation in the AD brain; (4) diminished energy metabolism and decreased cytochrome coxidase in the brain in AD; (5) advanced glycation end products (AGE), malondialdehyde, carbonyls,peroxynitrite, heme oxygenase-1 and SOD-1 in neurofibrillary tangles and AGE, heme oxygenase-1, SOD-1 in senile plaques; and (6) that amyloid beta peptide is capable of generating free radicals. So free radicals are possibly involved in the pathogenesis of neuron death in Alzheimer's disease (AD).

Cardiac Reperfusion Abnormalities:

Oxygen free radicals are highly reactive compounds causing peroxidation of lipids and proteins and are thought to play an important role in the pathogenesis of reperfusion abnormalities including myocardial stunning, irreversible injury, and reperfusion arrhythmias. Free radical

accumulation has been measured in ischemic and reperfused myocardium directly using techniques such as electron paramagnetic resonance spectroscopy and tissue chemiluminescence and indirectly using biochemical assays of lipid per oxidation products. Potential sources of free radicals during ischemia and reperfusion have been identified in myocytes, vascular endothelium, and leukocytes. Injury to processes involved in regulation ofthe intracellular Ca2+concentration may be a common mechanism underlying both free radical- induced andreperfusion abnormalities.Kidney:

Mitochondrial free radical production induces lipid peroxidation during myohemoglobinuria. Iron

catalyzed free radical formation and lipid peroxidation are accepted mechanisms of heme protein-induced acute renal failure. However, the source(s) of those free radicals which trigger lipid peroxidation in proximal tubular cells remains unknown. In conclusion, the terminal mitochondrial respiratory chain is the dominant source of free radical.

Fibrosis:

Oxygen, paraquat, nitrofurantoins, and bleomycin, produces pulmonary fibrosis. Radical-generating

agents such as iron and copper are also associated with liver fibrosis (cirrhosis) and fibrotic changes in other organs such as the heart. The induction of vitreous scarring by interocular iron or copper is also well known, as is the association of homocystinuria with fibrotic lesions of the arteries.

Adult Respiratory Distress Syndrome.
un planning pour une hygiène de vie loin des stress loin de la pollution et des produits polluants, un exercice physique régulier, et une consommation d'aliments riche en anti-oxydants est la meilleure façon d'éviter des maladies graves telles le cancer, l'alzheimer, les maladies vasculaires , et de conserver une peau saine et jeune.