As the MARS 500 volunteers had no cardiovascular or other pathology, or risk factors when entering the 10-Gingerol confinement habitat it is difficult to suggest a pathological mechanism for explaining the IMT increase. Moreover the diameter of the arteries concerned did not change at all. Thus we suggest that the increase in IMT should be related to one or several environmental factors of the confinement habitat. There was no change in gravity, atmospheric pressure, oxygen pressure, and slight changes in nutrition or physical activity�� compared to sedentary people not living in a confined environment. One may suggest that other factors like the isolation from the outside, the supposed outside risky environment itself, the absence of solar radiation could request an adaptation of some of the human body function and trigger metabolic processes. An oxidative 14alpha-hydroxy-Sprengerinin-C stress related to confinement could be a factor involved into the vascular changes observed during MARS 500. Oxidative stress is related to abnormal oxygen metabolism which produces nitric oxide and other element known to favor inflammatory reaction at the vascular level with increased IMT. Such hypothesis is supported by the results from a 105 d confinement experiment performed one year ago in the same facility as for MARS 500. This study reported an increase in oxidative stress with increase in oxi-hemoglobin, and decrease in some antioxidant defense. Other studies reported that confinement induce mental and physical stress that were found to disturb several cardiovascular target properties like arterial stiffness, endothelium properties, capillary permeability in relation with edema, or homodynamic parameters, or parameters regulating cardiovascular status like autonomous nervous system, insulin resistance, increase cathecholamines, angiotensine II, nitric oxide. In normal population longitudinal studies showed that social isolation in children was associated with higher cardiovascular risk factors when adults, and that social isolation in adult also increased cardiovascular risk factors. Depression, anxiety, mental disorder that can be induced by confinement are also considered as cardiovascular risk factors. Confinement was also found to reduce capacity to concentrate and increase the time needed to make a decision. Thus putting together several individuals of various personality may create tension or collaborative influence between the participant and generate mental stress. Coronary ectasia is an uncommon disease and its incidence has been reported as between 0.3 and 5% in different studies despite some exception. It is defined as the diameter of the ectatic segment being more than 1.5 times larger compared with an adjacent healthy reference segment. Most cases of CE are considered as a variant 
of coronary artery disease. The pathogenesis of CE is not completely illustrated. However, it is likely to involve the destruction of the arterial media, increased wall stress, thinning of the arterial wall, and progressive dilatation of the coronary artery segment. The development of coronary collaterals is an adaptive response to chronic myoischemia and serves as a conduit bridging the significantly stenotic coronary vessels. Collateral circulation can hence protect and preserve myocardium from episodes of ischemia, enhance residual myocardial contractility, and reduce angina symptoms and cardiovascular events. However, there is inter-individual difference of coronary collateral formation and the mechanisms for the different individual ability to develop collateral circulation are still unclear. Because CE are usually associated with atherosclerosis and even obstructive CAD resulting coronary ischemia, whether the presence of good coronary collateral or not is a very important issue.