Total antioxidant capacity in Eales’ disease, uveitis & cataract.

Background & objectives: The human system possesses antioxidants that act harmoniously to neutralize the harmful oxidants. This study was aimed to evaluate the serum total antioxidant capacity (TAC) as a single parameter in Eales’ disease (ED) and in an acute inflammatory condition such as uveitis and in cataract which is chronic, compared to healthy controls. Methods: The TAC assay was done spectrophotometrically in the serum of Eales’ disease cases (n=20) as well as in other ocular pathologies involving oxidative stress namely, uveitis and cataract (n=20 each). The oxidative stress measured in terms of TBARS, was correlated with the TAC. Individual antioxidants namely vitamin C, E and glutathione were also estimated and correlated with TAC. Results: TAC was found to be significantly lower in Eales’ disease with active vasculitis (0.28 ± 0.09 mM, P<0.001), Eales’ disease with healed vasculitis (0.67 ± 0.09 mM), uveitis (0.46 ± 0.09 mM, P<0.001) and cataract (0.53 ± 0.1 mM, P=0.001) compared to the healthy controls, with a TAC level of 0.77 ± 0.09 mM. The TAC was found to correlate positively with vitamin E levels (P=0.05), GSH (P=0.02) but not with vitamin C, as seen in ED cases. In ED cases supplemented with vitamin E and C, there was a significant increase in the TAC level (P=0.02). Interpretation & conclusions: The TAC measurement provided a comprehensive assay for establishing a link between the antioxidant capacity and the risk of disease as well as monitoring antioxidant therapy. This method is a good substitute for assay of individual antioxidants as it clearly gives the status of the oxidative stress in the disease process.

Transforming Growth Factor-beta Levels in Human Aqueous Humor of Glaucomatous, Diabetic and Uveitic Eyes

PURPOSE: Transforming growth factor-beta2 is known to be present at elevated levels in the aqueous humor of patients with primary open angle glaucoma (POAG) and diabetes but not in uveitis-related secondary glaucoma. We investigated total TGF-beta2 levels and levels of the active form of TGF-beta2 in the aqueous humor of eyes with different types of glaucoma. METHODS: The concentration of the total and active form of TGF-beta2 was measured in 63 patients with primary open angle glaucoma, neovascular glaucoma complicated with diabetes (NVG), and secondary open angle glaucoma complicated with uveitis (SOAG) using a double antibody 'sandwich-indirect' ELISA method. RESULTS: The levels of total TGF-beta2 in the aqueous samples of POAG, NVG, and SOAG were elevated. The levels of active TGF-beta2 in the aqueous samples of POAG, and NVG were also elevated, whereas the level of active TGF-beta2 was within the normal range in the aqueous samples of SOAG. CONCLUSIONS: These results suggest that the level of TGF-beta2 may play a role in the pathology of various types of glaucoma.

The Role of Nitric Oxide in Ocular Surface Cells

The role of nitric oxide (NO) in the ocular surface remains unknown. We investigated the conditions leading to an increase of NO generation in tear and the main sources of NO in ocular surface tissue. We evaluated the dual action (cell survival or cell death) of NO depending on its amount. We measured the concentration of nitrite plus nitrate in the tears of ocular surface diseases and examined the main source of nitric oxide synthase (NOS). When cultured human corneal fibroblast were treated with NO producing donor with or without serum, the viabilities of cells was studied. We found that the main sources of NO in ocular surface tissue were corneal epithelium, fibroblast, endothelium, and inflammatory cells. Three forms of NOS (eNOS, bNOS, and iNOS) were expressed in experimentally induced inflammation. In the fibroblast culture system, the NO donor (SNAP, S-nitroso-N-acetyl-D, L-penicillamine) prevented the death of corneal fibroblast cells caused by serum deprivation in a dose dependent manner up to 500 micrometer SNAP, but a higher dose decreased cell viability. This study suggested that NO might act as a doubleedged sword in ocular surface diseases depending on the degree of inflammation related with NO concentration.

Uveítis experimental por ácido lipoteícoico como modelo de enfermedad humana / Experimental uveitis induced by lipoteichoic acid as human disease model

Propósito: examinar la capacidad del ácido lipoteicoico (ALT) para inducir inflamación intraocular en ratas. Métodos: ALT obtenidos de Staphylococcus aureus y de tres diferentes especies estreptocócicas fueron disueltos en solución salina a distintas concentraciones e inyectados en el cojinete de una pata de ratas Lewis hembras. El efecto inflamatorio intraocular fue evaluado por medio de métodos clínicos e histológicos y la intensidad de la inflamación en la cámara anterior (CA) fue evaluada por medio de la determinaión de la concentración de proteínas y densidad de células en el humor acuoso (HA). Finalmente, posibles mediadores inflamatorios intraoculares de la enfermedad fueron evaluados a través de la determinación semicuantitativa de ácido ribonucleico mensajero (ARNm) de un panel de citoquinas. Resultados: ALT de S. aureus indujo una intensa inflamación intraocular 24-30 horas después de su inyección. La reacción inflamatoria se indujo de un modo dosis dependiente. A una dosis de 15 mg/kg de ALT, la concentración de proteínas y recuento de células en HA fueron 5,6 ñ 0,5 mg/ml y 4075 ñ 1193 células/µl respectivamente. Después de la inyección de ALT de origen estreptocócico no se detectaron células en la CA, mientras que la concentración de proteínas se elevó 2-3 veces comparada con el grupo control