The Effect of Chemically Modified Tetracycline on the Inflammatory Reaction in Endotoxin-Induced Uveitis

PURPOSE: This study was planned to find out the effect of CMT (chemically mediated tetracycline) in experimentally induced uveitis (EIU) model. METHODS: 54 Lewis rats were divided into three groups. For two experimental groups, CMT-3 and CMT-8 were used and for control group, placebo (CMC) was used. Each material was orally administered for 1 week. Then lipopolysaccharides (LPS) were administrated subcutaneously into footpads in all groups. The progression of inflammation and lens opacity was evaluated with slit lamp biomicroscope. Nitrite and Nitrate, stable oxidative products of nitric oxide in the aqueous humor, and TNF-alpha and IL-1beta in the uveal tissue were measured. The expression of iNOS was evaluated immunohistochemically. RESULTS: More severe corneal edema and sutural opacity of lens, along with the finding of more intense uveitis were noted in control than the CMT-3 and CMT-8, while no significant difference between the finding of CMT-3 and CMT-8 was noted. The concentration of NO, TNF-alpha, IL-1beta and the expression of iNOS were significantly decreased in CMT-3 and CMT-8, and they had a close correlation with these inflammatory signs. CONCLUSIONS: These results suggest that CMT-3 and CMT-8 inhibit the progression of inflammation in EIU and this effect is related to the inhibition of the NO production in aqueous humor. But we need a further evaluation to seek the relation between CMT and metalloproteinase in EIU, combined with studies of other biochemical changes in cornea, anterior chamber and lens.

The Electrolyte Changes of Pig`s Lens in Experimentally Induced Cataract

Protein accounts for over one third of the human lens, the remaining two thirds being water. The other constotuents of the lens including lipids, amino acids, electrolytes and a variety of peptides and carbohydrates, account for about 1% of the lens wet weight. Since transparency of the lens is so highly dependent on protein order and structural integrity, it is not surprising that relatively small changes in any of these parameters might lead to the development of opacification resulting in a cataract.We have analyzed electrolytic differences between normal lens and lens of experimentally induced cataract to find the important factor in including cataract after we had extracted one hundred eight pig lenses. We divided these experimentally induced cataract into a group of normal lens capsule and another group of lenses which we performed with a 26 gauge needle. The sodium level was decreased in 15% mannitol solution and increased in normal saline. In every solution the potassium level was decreased. The chloride level was decreased in the 15% mannitol solution and increased in the normal saline solution. The calcium level also was decreased in mannitol and distilled water.Our results indicate that the potassium level of the experimentally induced cataracts decreased in any conditions and may be an important factor in inducing cataract.

The Effect of Intravitreal Injection of Retinoic Acid on Experimentally Induced Proliferative Vitreoretinopathy using Human Retinal Prgment Epithelium in Rabbits

The retinoic acid have been demonstrated to modulate the growth and differentiation of several cell types including retinal pigment epithelium.We evaluated the effect of intravitreal infection of retinoic acid on experimentally induced PVR using human retinal pigment epithelium in the rabbit. 35 eyes of rabbit were induced PVR by injecting of human retinal pigment epithelial cells and were divided into three groups; Control group, group 1(retinoic acid 0.05mg/0.1ml DMSO was injected) and group 2(retinoic acid 0.1mg/0.1ml DMSO was injected). The stages of PVR were observed on days 3, 7, 14 and 28. The mean PVR stage progressed in all three groups. The PVR stage in control group is lower than other groups on days 3 and the PVR stage in group 3 is higher than other groups on days 28. In conclusions, intravitreal injected retinoic acid cannot inhibit PVR proliferation on 0.05 and mg/0.1ml concentration and it had toxic effect on retina in 0.1mg/0.1ml concentration. This results may present the lower limit of concentration to use retinoic acid intravitreously.