الفهرس 
Overview of PsoriasisOnly 14 pages are availabe for public view
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Abstract
Psoriasis (PS) is a common chronic, relapsing, immune-mediated disease involving the skin and joints of genetically predisposing individuals, which potentially shares the disease pathways with other chronic inflammatory diseases such as rheumatoid arthritis and inflammatory bowel diseases. Studies have estimated the prevalence of psoriasis to be 0.6% to 4.8% of the population worldwide ,The prevalence of psoriasis in Egypt was estimated as 3% of the population. a polygenic disease issoriasis PThere is much evidence that The disease is of unknown .factorsmodified to expression by triggering etiology, although it is thought to be caused by the interaction of various genes and environmental factors with the immune system. It is believed that this interaction is responsible for the increased production of T helper-1 cytokines, tumor necrosis factor –alpha, and other mediators, which induce an inflammatory skin phenotype with abnormal keratinocyte proliferation, differentiation and skin vascularization. Today, psoriasis vulgaris is recognized as the most prevalent autoimmune disease caused by inappropriate activation of the cellular immune system . Despite numerous studies, the pathogenesis of PS has not been fully elucidated. However, many pathogenic theories have been suggested . The exact sequence of events, as well as the molecular mediators that lead to hyperproliferative responses, is yet to be defined. As a potent regulator of keratinocyte growth and differentiation, the multifunctional signaling molecule nitric oxide (NO) has been considered to be a strong candidate in the pathogenesis of psoriasis .
SUMMARY
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NO, a gaseous free radical was reported to be functionally equivalent to endothelium derived relaxing factor (EDRF), which causes net vasodilatation . NO is produced by various group of enzyme termed as nitric oxide syntheses (NOS) which are present in body.Three isoforms of NOS are present whose names are termed on the basis of their activities, which include, neuronal NOS (nNOS), inducible NOS (iNOS) and endothelial NOS (eNOS). iNOS produces large quantities of NO upon stimulation, such as by proinflammatory cytokines (e.g. Interleukin-1, Tumor necrosis factor alpha and Interferon) . Inducible nitric oxide synthase (iNOS) was found to be expressed in the keratinocytes of psoriatic lesions ,Furthermore an increase in mRNA expression of iNOS in skin lesions in comparison with uninvolved skin have been reported . Therefore, the aim of this work is to demonstrate the expression of calcium-independent iNOS in normal human and psoriatic skin by using immunohistochemistry with subtype-specific antibodies and assess the role of Inducible nitric oxide synthase in pathogenesis of psoriasis and correlate its expression with the severity of Psoriasis. This study was carried out on 24 patients presenting with psoriasis. The diagnosis was made on clinical and histopathological bases and all patients had received neither topical nor surgical treatment for at least2 weeks before skin biopsy. For comparison purposes, 7 specimens from normal volunteers during plastic surgery are included in the study representing controls. Both patients and control subjects were selected randomly from the Outpatient Dermatology Clinic, Menoufiya University Hospital during the period between June 2011 and January 2013.
SUMMARY
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The age of the psoriatic patients ranged from8 to 65 with a mean age of 34.88+ 13.69 years, while that of control group ranged from 17 to 45 years with a mean age of 32.14+ 10.31years. There were12 males (50%) and 12 females (50%) with 1: 1 as a male to female ratio comprised the psoriatic group. The disease duration ranged between 2 and 30 years with a mean of (10.92+6.62). The PASI score of the psoriatic cases ranged from 0.6 to 60.0 with a mean of 23.06 ± 21.41.