Peripheral Sterile Corneal Ring Infiltrate After Riboflavin-UVA Collagen Cross-Linking in Keratoconus

Purpose: To present 7 cases of peripheral sterile corneal infiltrates that occurred after corneal cross-linking (CXL) for progressive keratectasia. Methods: Seven patients who had their progressive keratoconus documented underwent corneal deepithelization and subsequently CXL, which was performed with the application of 0.1% riboflavin with 20% dextran, and exposure to UVA light (370 nm, 2.9-3.1 mW/cm(2)) for 30 minutes. Results: Nearly a week after the procedure, the patients presented with peripheral stromal infiltrates. The ring-like infiltrates were superficial and were present at the 9.0-mm zone. Sterile infiltration was diagnosed. Patients were treated with topical corticosteroids, and complete resolution was achieved after a few weeks of treatment. Conclusions: We hypothesize that the phototoxic effect on the corneal stroma may be the main mechanism that triggers these infiltrates. Alternatively, alterations in antigenicity that occur in native proteins after CXL could result in patients recognizing the proteins as nonself and mounting immune responses.

Um modelo de projeto de layout para ambientes job shop com alta variedade de peças baseado nos conceitos da produção enxuta

Segundo Canem e Williamson (1998), o planejamento do layout é importante, pois normalmente representa os maiores e mais caros recursos da organização. Além disso, a localização e disposição física dos equipamentos no chão de fábrica têm impacto em diversos fatores como nível de estoque em processo, tamanho dos lotes de transferência, dificuldade no gerenciamento das atividades, movimentação de pessoas e produtos, entre outros. Portanto, o estudo de conceitos de arranjo físico e o desenvolvimento de modelos de projeto do layout, que visem a otimização dos recursos de produção, são de vital importância na busca pela melhoria dos sistemas produtivos. Neste contexto, este artigo apresenta um novo modelo de projeto de layout, para ambientes job shop com ampla variedade de peças. O modelo foi desenvolvido durante uma pesquisa de doutorado e foi aplicado em algumas empresas do setor metal mecânico. Os resultados obtidos comprovaram a eficiência do modelo projetado. O objetivo do modelo consiste em conduzir a equipe de projeto de layout a desenvolver alternativas de arranjo físico que estejam em consonância com conceitos e princípios da filosofia de produção enxuta. Vale ressaltar novamente que o modelo foi desenvolvido para ambientes com alta variedade de peças, ambientes esses em que, devido à dificuldade em se projetar o arranjo físico, as empresas terminam por adotar o layout funcional, conceito esse de arranjo físico que apresenta sérios problemas como excesso de transporte, altos níveis de estoques em processo, etc.

The relative roles of DNA damage induced by UVA irradiation in human cells

UVA light (320–400 nm) represents approximately 95% of the total solar UV radiation that reaches the Earth’s surface. UVA light induces oxidative stress and the formation of DNA photoproducts in skin cells. These photoproducts such as pyrimidine dimers (cyclobutane pyrimidine dimers, CPDs, and pyrimidine (6-4) pyrimidone photoproducts, 6-4PPs) are removed by nucleotide excision repair (NER). In this repair pathway, the XPA protein is recruited to the damage removal site; therefore, cells deficient in this protein are unable to repair the photoproducts. The aim of this study was to investigate the involvement of oxidative stress and the formation of DNA photoproducts in UVA-induced cell death. In fact, similar levels of oxidative stress and oxidised bases were detected in XP-A and NER-proficient cells exposed to UVA light. Interestingly, CPDs were detected in both cell lines; however, 6-4PPs were detected only in DNA repairdeficient cells. XP-A cells were also observed to be significantly more sensitive to UVA light compared to NER-proficient cells, with an increased induction of apoptosis, while necrosis was similarly observed in both cell lines. The induction of apoptosis and necrosis in XP-A cells using adenovirus-mediated transduction of specific photolyases was investigated and we confirm that both types of photoproducts are the primary lesions responsible for inducing cell death in XP-A cells and may trigger the skin-damaging effects of UVA light, particularly skin ageing and carcinogenesis.