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Background: The rd1 mouse retina displays fast degeneration of photoreceptors resulting in a depletion of almost all rod photoreceptors by postnatal day 21 (PN21). To evaluate the role of proteinases in the pathophysiology of this animal model of retinitis pigmentosa, C3H rd1 and congenic wild-type (wt) mice retinas were analyzed. Material and Methods: The cellular localization and levels of proteins, matrix metalloproteinases (MMPs), their endogenous inhibitors (TIMPs), total sulfated glycosaminoglycans (sGAG) and nature of saccharides in rd1 and wt retinal extracts were compared. Results: MMP-2/TIMP-2 and MMP-9/TIMP-1 were predominantly localized in the interphotoreceptor matrix (IPM) of both genotypes, but MMP-2/TIMP-2 also appeared in the Müller cell fibers of rd1 retina. In rd1 retinal extracts the levels of total proteins were lower and those of active MMP-9, MMP-2, TIMP-1 and total sGAG were higher than those of wt extracts. Despite an increase in TIMP-1, active MMP-9/MMP-2 were disproportionately elevated in rd1 compared to wt retina. With increasing age, MMPs in wt retinas were decreased but were increased in rd1. The sialylation of proteoglycans in PN2 and PN7 rd1 retinas was lower, and galactosylation was higher than that in wt retinas. Conclusions: MMP-9/MMP-2 and TIMP-1/TIMP-2 are associated with IPM, possibly after secretion by retinal pigmented epithelial cells. In degenerating rd1 retina, MMP-2/TIMP-2 are associated with the Müller cell fibers, which apparently play a central role in modifying the balance between MMPs and TIMPs. Elevated sGAG and proteolysis due to an imbalance in the levels of TIMPs and active MMP-9/MMP-2 in rd1 retina possibly contribute to retinal degeneration in the rd1 mouse.

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Similar localization of both cathepsin-B and cysC in wt and rd1 retinas along with lower proteins and higher cathepsin activity in rd1 retinal extracts and RCM are consistent with their localization in extracellular matrix and a role in physiopathologic remodeling in wt and rd1 retinas.

Malondialdehyde, reduced glutathione, glutathione peroxidase, glutathione reductase and cysteine protease cathepsins at postnatal (PN) days 2, 7, 14, 21 and 28 in controls (wt) and the retinal degeneration 1 (rd1) mouse model for retinitis pigmentosa retinas were measured to determine oxidative stress. In PN28 wt and PN2 rd1 retinas, elevated malondialdehyde and low glutathione peroxidase activity indicate higher oxidative load, despite higher reduced glutathione in PN2 rd1 retinas. This is due to physiological exposure to light and retinal vascular/neural restructuring, respectively. Compared with wt retinas, relatively high malondialdehyde at PN2 and cathepsin levels at PN14, 21 and 28 in rd1 retinas indicate that cells of the residual inner retina also contribute to the oxidative stress and retinal degeneration.

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Nephritis was induced in 300, 18-day-old male Arbor Acre broiler chicks by feeding diets high (42.28%) in protein, high (3.27%) in calcium, containing urea (5%), or deficient in vitamin A. Various hematological parameters were studied at weekly intervals. Normocytic-normochromic anemia, characterized by a decrease in total erythrocyte counts, hemoglobin, packed cell volume, and an increase in erythrocyte sedimentation rate, was evident in the birds kept on diets high in protein, high in calcium, or deficient in vitamin A. Increased total erythrocytes, hemoglobin packed cell volume, and erythrocyte sedimentation rate was observed in birds fed urea. Differential leucocyte counts revealed lymphopenia, heterophilia and monocytosis in birds kept on diets high in protein, containing urea, or deficient in vitamin A. However, lymphocytosis, heteropenia , and monocytosis were recorded in birds fed the high calcium diet.