Implications of Oxidative Stress and Cellular Senescence in Age-Related Thymus Involution.

The human thymus is a primary lymphoepithelial organ which supports the production of self-tolerant T cells with competent and regulatory functions. Paradoxically, despite the crucial role that it exerts in T cell-mediated immunity and prevention of systemic autoimmunity, the thymus is the first organ of the body that exhibits age-associated degeneration/regression, termed "thymic involution." A hallmark of this early phenomenon is a progressive decline of thymic mass as well as a decreased output of naïve T cells, thus resulting in impaired immune response. Importantly, thymic involution has been recently linked with cellular senescence which is a stress response induced by various stimuli. Accumulation of senescent cells in tissues has been implicated in aging and a plethora of age-related diseases. In addition, several lines of evidence indicate that oxidative stress, a well-established trigger of senescence, is also involved in thymic involution, thus highlighting a possible interplay between oxidative stress, senescence, and thymic involution.

Anatomical variations in the branches of the human aortic arch in 633 angiographies: clinical significance and literature review.

BACKGROUND: The variations of vessels arising from the aortic arch are numerous. The purpose of the present study is the description of the aortic arch branches' variations, in order to offer useful data to anatomists, radiologists, vascular, neck and thorax surgeons. In addition, literature has been reviewed so as to enable a comparison of our results with those of other studies and an analysis of the variations' clinical implications is possible. MATERIALS AND METHODS: A total of 633 digital subtraction angiographies of Caucasian Greek patients were examined. No computed tomography or magnetic resonance angiographies were included. RESULTS: Eight types of the aortic arch were found. The classification from I to VIII was made according to the incidences recorded, with type I being the most and type VIII being the least frequent. Type I, brachiocephalic trunk (BT), left common carotid artery (LCC), left subclavian artery (LS), 527 (83%); type II, BT with LCC and LS, 96 (15%); type III, BT, LCC, left vertebral artery (LV), LS, 5 (0.79%); type IV, right subclavian artery (RS), carotids in common, LS, 1 (0.16%); type V, carotids in common-LS, RS, 1 (0.16%); type VI, carotids and subclavians in common, 1 (0.16%); type VII, RS, right common carotid artery (RCC), LCC, LS, 1 (0.16%); type VIII, BT, thyroidea ima, LCC, LS, 1 (0.16%). CONCLUSIONS: Despite the fact that the variations in question are usually asymptomatic, they may cause dyspnea, dysphagia, intermittent claudication, misinterpretation of radiological examinations and complications during neck and thorax surgery. Furthermore, these variations may be accompanied by other congenital abnormalities.