الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Alopecia areata (AA) is a common dermatological problem that describes non scarring loss of hair in defined single or multiple areas of the skin, mainly the scalp. AA affecting about 2% of new patients attending dermatologic clinics with prevalence peaks between the second and fourth decades of life and affects males and females equally with positive family history in about 20% of patients.
Alopecia areata is asymptomatic disease commonly appears abruptly on the scalp as a patch of clearing with no evidence of scarring, eyebrow, eyelash and axillary involvement may occur and there may be associated nail abnormalities. Its presentation is variable from a single patch of hair loss to complete scalp (AT) and/or body hair loss (AU) to diffuse scalp hair thinning without discrete patches of loss,. Ophiasis, ophiasis inversus and reticular pattern are rare forms of AA.
Classic AA lesions are well demarcated, round or oval, completely bald, smooth-surfaced patches. Exclamation mark hairs is characteristic finding and initial sparing of white hairs is an interesting feature of AA.
In AA, significant disruption of the hair growth cycle clearly occurs but the etiology of AA is not known exactly and the molecular mechanisms that lead to hair loss are poorly understood. However, factors such as genetic predisposition, autoimmunity and stress have been suggested, the role of infectious factors has been also proposed and oxidative stress is another probable mechanism characterized by an increase in free radical production exceeding the intracellular antioxidant defence, however it is hypothesized that AA is a tissue-restricted autoimmune disease mediated by T lymphocytes. Immunohistochemical studies have shown peri- and infra-follicular inflammatory infiltrate which damages hair follicles.
Oxidants are formed as a normal product of aerobic metabolism but can be produced at elevated rates under pathophysiological conditions, An antioxidant is any substance that when present in low concentrations compared with those of an oxidizable substrate significantly delays or prevents its oxidation, Oxidative stress is a disturbance in the balance between reactive oxygen species (ROS) and endogenous antioxidant defenses, leading to oxidation of lipids, proteins, and DNA in ways that impair cellular function, Malondialdehyde (MDA) is a final product of peroxidation process and it is considered as a biomarker of lipid oxidation.
Antioxidants are being consumed under conditions of oxidative stress generation and that depletion of endogenous antioxidants would be an indirect reflection of increased oxidative stress. The cellular antioxidant systems can be, enzymatic as Glutathione peroxidase (GPx), Superoxide dismutase (SOD) and Catalases or non enzymatic as glutathione(GSH), selenium (Se), zinc (Zn) and vitamins (A,C and E), SOD is considered as the first line of defense against ROS where it dismutes .O2- into H2O2 which will be converted by GPx or CAT into H2O.