The Role of Oxidative Stress in the Pathogenesis of Age-Related Macular Degeneration

Over the past decade, it has become increasingly recognized that airways inflammation is one of the major components of asthma. Until recently, measurements of bronchial responsiveness and mediators of allergic reactions were the only methods of studying pathogenetic mechanisms in asthma. With improved diagnostic procedures such as fiberoptic bronchoscopy, it has become possible to investigate these mechanisms and the resulting inflammatory changes in situ. BAL has highlighted the presence of mast cells and eosinophils and has given proof of their mediator participation in airways inflammation and hyperresponsiveness. Endobronchial biopsies have so far yielded results that are similar to those obtained from postmortem studies, although it appears that there are varying degrees of inflammation in living asthmatics. Even in mild disease, the histopathologic features of bronchial asthma are consistent with chronic inflammation. Indirect evidence obtained from allergen challenge leading to increased bronchial hyperresponsiveness during LAR, and direct evidence of inflammatory cells and their mediators in the airway mucosa and lumen after allergen challenge argue for an active role of cells in bringing about inflammatory changes. At present, however, it is not possible to relate precisely the findings obtained by bronchoscopy to the clinical presentation and progression of asthma. Cell activation with production of potent mediators of inflammation may be more relevant to inflammation than the simple presence of these cells in the airways. Almost all the inflammatory cells present in the bronchial wall and lumen have been implicated in the pathogenesis of mucosal inflammation in asthma, but with our current state of knowledge, none can be singled out as the most important contributor. The mast cell was the first to be investigated in depth, and despite the accumulation of large amounts of data concerning its ultrastructure and function, it remains uncertain to what extent this cell is involved in inflammatory responses. Thus, while its main role appears to be that of initiator of allergen-induced responses, the eosinophil has attracted more attention as a proinflammatory cell rather than as an antiinflammatory cell with a capacity to be selectively recruited from the circulation in response to IgE-dependent signals. The eosinophil secretes potent mediators that cause damage to the bronchial epithelium and lead to bronchoconstriction. The role of other cells is at present not as well defined.(ABSTRACT TRUNCATED AT 400 WORDS)

Mucosal inflammation in asthma.

Objective To review and synthesize information concerning the pathogenesis ofage-related macular degeneration (AMD). Methods Review of the English-language literature. Results Five concepts relevant to the cell biology of AMD are as follows: (1)AMD involves aging changes plus additional pathological changes (ie, AMD isnot just an aging change); (2) in aging and AMD, oxidative stress causes retinalpigment epithelial (RPE) and, possibly, choriocapillaris injury; (3) in AMD(and perhaps in aging), RPE and, possibly, choriocapillaris injury resultsin a chronic inflammatory response within the Bruch membrane and the choroid;(4) in AMD, RPE and, possibly, choriocapillaris injury and inflammation leadto formation of an abnormal extracellular matrix (ECM), which causes altereddiffusion of nutrients to the retina and RPE, possibly precipitating furtherRPE and retinal damage; and (5) the abnormal ECM results in altered RPE-choriocapillarisbehavior leading ultimately to atrophy of the retina, RPE, and choriocapillarisand/or choroidal new vessel growth. In this sequence of events, both the environmentand multiple genes can alter a patient's susceptibility to AMD. Implicit inthis characterization of AMD pathogenesis is the concept that there is linearprogression from one stage of the disease to the next. This assumption maybe incorrect, and different biochemical pathways leading to geographic atrophyand/or choroidal new vessels may operate simultaneously. Conclusions Better knowledge of AMD cell biology will lead to better treatmentsfor AMD at all stages of the disease. Many unanswered questions regardingAMD pathogenesis remain. Multiple animal models and in vitro models of specificaspects of AMD are needed to make rapid progress in developing effective therapiesfor different stages of the disease.

https://jamanetwork.com/journals/jamaophthalmology/articlepdf/416250/EMO20000.pdf

Current Concepts in the Pathogenesis of Age-Related Macular Degeneration

Erdheim-Chester disease. Clinical and radiologic characteristics of 59 cases.

Hemangiomas are the most common soft-tissue tumors of infancy, occurring in approximately 5 to 10 percent of one-year-old children. Despite the frequency of these tumors, their pathogenesis is not completely understood, and the best approach to their management remains controversial. Research on angiogenesis, an improved knowledge of the classification of the vascular anomalies of infancy, advances in imaging techniques, recently identified complications, and new therapeutic approaches, such as treatment with interferon and lasers, have altered our understanding of this common childhood problem and the way we approach it. The term hemangioma has traditionally been applied to a variety of vascular . . .

https://www.nejm.org/doi/pdf/10.1056/NEJM199907153410307

Zeynel A. Karcioglu

Papers

Capillary hemangioma (infantile periocular hemangioma)

Risk factors for metastasis in retinoblastoma.

Tumor Seeding in Ocular Fine Needle Aspiration Biopsy

Zinc in the eye.

Penetrating orbital injury with organic foreign bodies.