Oxidative stress of crystalline lens in rat menopausal model / O estresse oxidativo do cristalino em modelo de rata na menopausa

ABSTRACT Purpose: To evaluate lenticular oxidative stress in rat menopausal models. Methods: Forty Wistar female albino rats were included in this study. A total of thirty rats underwent oophorectomy to generate a menopausal model. Ten rats that did not undergo oophorectomy formed the control group (Group 1). From the rats that underwent oophorectomy, 10 formed the menopause control group (Group 2), 10 were administered a daily injection of methylprednisolone until the end of the study (Group 3), and the remaining 10 rats were administered intraperitoneal streptozocin to induce diabetes mellitus (Group 4). Total oxidant status (TOS), total antioxidant capacity (TAC), and oxidative stress index (OSI) measurements of the crystalline lenses were analyzed. Results: The mean OSI was the lowest in group 1 and highest in group 4. Nevertheless, the difference between the groups was not statistically significant in terms of OSI (p >0.05). The mean TOS values were similar between the groups (p >0.05), whereas the mean TAC of group 1 was significantly higher than that of the other groups (p <0.001). Conclusions: Our results indicate that menopause may not promote cataract formation.

RESUMO Objetivo: Avaliar o estresse oxidativo lenticular em modelos de ratas na menopausa. Métodos: Quarenta ratos albinos femininos tipo Wistar foram incluídos neste estudo. Trinta ratas foram submetidas à ooforectomia para gerar o modelo de menopausa e 10 ratas formaram o grupo controle (Grupo 1). Dentre as ratas ooforectomizadas, 10 formaram o grupo controle menopausa (Grupo 2), 10 ratas receberam injeção diária de metilprednisolona até ao final do estudo (Grupo 3) e 10 ratas receberam estreptozotocina por via intraperitoneal para induzir diabetes mellitus (Grupo 4). O estado oxidante total (TOS), a capacidade total antioxidante (TAC) e as medições do índice de estresse oxidativo (OSI) dos cristalinos foram analisados. Resultados: A média de OSI foi menor no grupo 1 e maior no grupo 4. Todavia, a diferença entre os grupos não foi estatisticamente significativa (p>0,05). Os valores médios TOS foram semelhantes entre os grupos (p>0,05), enquanto a média de TAC grupo 1 foi mais elevada do que nos outros grupos ( p<0,001). Conclusões: Nossos resultados indicam que a menopausa podem não promover a formação de catarata.

Catarata em árvore de Natal / Christmas tree cataract

A catarata em árvore de Natal é um tipo raro de opacificação do cristalino caracterizado por depósitos policromáticos em forma de agulhas no córtex profundo e no núcleo do mesmo, que podem ser isolados ou associados a outras opacidades. Neste estudo relatamos e registramos, por meio de fotografias, dois casos deste tipo de opacidade cristaliniana.

The Christmas tree cataract is a rare type of lens opacification characterized by deposits of needle-shaped polychromatic cortex deep in the core, that can be isolated or associated with other opacities. We report and record, through photographs, two cases of this type of lens opacity.

Cations, oxidants, light as causative agents in senile cataracts

Lens transparency is a function of regular cell shape, regular cell volume, minimal extracellular space, and minimal scatter elements. The cellular structure and molecular structure of the lens is reviewed. The importance of the cytoarchitecture especially the sutures, is discussed. The high cholesterol: phospholipid ratio of the lens fiber cell membranes is related to the functions of low permeability, low fluidity, and mechanical stability. Also reviewed are the contributions of the lens crystallins to lens clarity and to lens refractive index. The importance of intracellular and extracellular cation and water concentrations are reviewed. Finally the effects of systemic diseases, oxidation, and light on lens clarity are discussed relative to changes in lens fiber cell cation concentrations

Melanins and lens pigments: a comparative study

Based on previous findings that lens pigments and melanins share many physicochemical properties, human lens pigments and natural (hair) and synthetic melanins were submitted to oxidation with permanganate under strong acidic conditions. This procedure has been utilized for the characterization of melanins and results in the well defined products, thiazole-4,5-dicarboxylic acid (TDCA) and pyrrole-2,3,5-tricarboxylic acid (PTCA), which can be quantitated by high performance liquid chromatography (HPLC). PTCA is regarded as a marker of black eumelanins and was therefore a main component of synthetic DOPA-eumelanin and dark hair. Its identity was established by synthesis from 5-hydroxyindole-2-carboxylic acid. TDCA derives from pheomelanins and was therefore an important component of red hair and synthetic GSH-pheomelanin. TDCA was identified by its retention time relative to PTCA. The analysis of a series of cataract digests of increasing pigmentation (type I < type IV < type V) and a purified fraction of lens pigments (DE52 pigment) revealed the presence in these preparations of both PTCA and TDCA. The concentration of TDCA significantly increased with the degree of pigmentation of the digests and reached a maximum in the DE52 pigment. The TDCA/PTCA ratio was high in the lens preparations and comparable to that given by hair pheomelanin. These findings support that pheomelanin is an integral part of lens pigments. By comparing the yields of TDCA in GSH-pheomelanin and in the purified lens pigment, a 9 per cent contribution of pheomelanin to the lens pigment was estimated