ABSTRACT
Several physico-chemical parameters of lenses were investigated in IOR/Hab mice with hereditary cataract aged 4, 6, 8 weeks, i.e. at the stage preceding the development of cataract. The level of restored glutathione in the IOR/Hab lenses /2.0 mM/ was the lowest as compared to other lines but almost the same as in CBA/J /2.3 mM/. In the process of studying protein fluorescence quenching in cortex homogenates by nitrate anions a significant increase of the quenching constant was discovered in IOR/Hab mice: 10.4 M-1 in four-week animals and up to 32.3 M-1 in eight-week animals. The data obtained suggest that a progressing growth of the quenching constant in line IOR/Hab lenses is related to a decreased density of the protein negative charge resulted from their decreased phosphorylation.
Subject(s)
Cataract/genetics , Eye Proteins/analysis , Fluorescence , Animals , Cataract/metabolism , Cataract/pathology , Glutathione/analysis , Mice , Mice, Inbred C57BL , Mice, Inbred CBA , Models, Biological , Spectrometry, Fluorescence , Sulfhydryl Compounds/analysisABSTRACT
The accessibility of tryptophanyl fluorophores in crystalline proteins to water molecules was estimated by measuring the enhancement of the fluorescence of lens homogenates in 70% D2O as compared to 100% H2O. Assuming that two sorts of fluorophores exist in the proteins, one entirely accessible to H2O and D2O and the other--absolutely not, we have calculated the portion of either group in the protein fluorescence (alpha and 1-alpha, correspondingly). Measurement of murine lens homogenates fluorescence at different stages of radiation-induced cataract, initiated with total gamma irradiation in a dose 5 Gy have shown an increased accessibility of tryptophanyl for water with cataract development. At earlier stages of cataract (appearance of scattered dot opacities) the portion of water-accessible tryptophanyl increased from 0.14 to 0.18, i.e. by a factor of 1.3. The data obtained suggest that protein globules unfold in the coarse of cataract development.
Subject(s)
Cataract/metabolism , Crystallins/metabolism , Fluorescence , Radiation Injuries, Experimental , Water/metabolism , Animals , Cataract/etiology , Crystallins/analysis , Mice , Mice, Inbred C57BL , Mice, Inbred CBA , Radiation Dosage , Spectrometry, FluorescenceABSTRACT
Structural changes in the lens and vitreous body exposed to short-pulse Nd:YAG Q-switching laser were under study. The laser was focussed in the lens nucleus or vitreous center plane. A pulse energy was 7.1-9.3 mJ, with a total of 75-100 pulses. Cataract development was induced via the formation of cavities with the guidance spot focal plane localized in the lens nucleus plane. When the focus was in the vitreous body and the laser operated in a similar energy mode, great numbers of small cavities rapidly formed, this evidencing a shock wave propagation. Specific and structural conformational changes in the lens and vitreous protein molecules were detected by nitrate quenching of the triptophane amino acid residue fluorescence. Laser exposure was found to reduce triptophanile availability for nitrates, this evidencing protein complexes aggregation (collapse); besides, laser exposure essentially increased the amino acid residue quenching constants, which fact pointed to a decreased density of the vitreous collagen and lens crystalline negative charges (increased hydratation). These findings permit a conclusion that the shifts connected with injury to the vitreous body, with macular edema, or with detachment of the retina after exposure to Nd:YAG laser may be due to collapse of the vitreous gel liquified components.
Subject(s)
Lasers/adverse effects , Lens, Crystalline/injuries , Vitreous Body/injuries , Animals , Cataract/etiology , Chemical Phenomena , Chemistry, Physical , Crystallins/analysis , Crystallins/metabolism , Crystallins/radiation effects , Disease Models, Animal , Eye Proteins/analysis , Eye Proteins/metabolism , Eye Proteins/radiation effects , Laser Therapy/instrumentation , Lens, Crystalline/metabolism , Male , Rabbits , Spectrometry, Fluorescence/methods , Time Factors , Vitreous Body/metabolismABSTRACT
The level of lipid peroxidation products (LPP) was determined in the aqueous humor from the anterior chamber of patients with cataract and donor eyes. The content of LPP in senile cataract aqueous humor was shown to be significantly increased. To determine the possible mechanism of LPP increase in aqueous humor, human lenses at different stages of cataract as well as transparent human and rabbit lenses were incubated for 3 hours in 3.0 ml medium containing liposomes (0.5 mg/ml) prepared from phospholipids from the egg yolk and 0.14 M NaCl + 0.01 M TRIS-HCl buffer, pH 7.4). Corrections were made for phospholipid autooxidation. The level of LPP accumulation in the medium was determined by MDA assay. The rate of LPP production increased significantly in transparent lenses and in early senile cataract, as compared to controls and advanced (mature) cataracts. EDTA (1 mM), superoxide dismutase (114 u/sample), catalase (900 u/sample), chelated iron (III): Fe3+-ADP addition to the incubation medium depressed the level of LPP accumulation. This suggests the participation of Fe2+, O2-., H2O2 in the mechanism of LPP production in the lens. The induction of lipid peroxidation in the lens can be significant for leukotriene and prostaglandin synthesis in the eye.
