Endostatin, a proteolytic fragment of type XVIII collagen, has been shown to inhibit angiogenesis, tumor growth, and endothelial cell proliferation and migration. We analyzed its functions in vivo by generating transgenic mice in which it was overexpressed in the skin and lens capsule under the keratin K14 promoter. Opacity of the lens occurred at 4 months of age in the mouse line J4, with the highest level of endostatin expression. The lens epithelial cells appeared to lose contact with the capsule and began to vacuolize. In 1-year-old mice the lens epithelial cell layer had entirely degenerated, and instead, large plaques of spindle-shaped cells had formed in the anterior region of the lens. Moreover, a widening of the epidermal basement membrane (BM) zone of the skin was observed in electron microscopy. The epidermal BM was conspicuously altered in the J4 mice with high transgene expression, including clear broadening and occurrence of pearl-like protrusions in some areas, whereas the BM was more even in appearance but consistently broadened in the mouse line G20 with moderate transgene expression. In both lines the BM was continuous. Measurements indicated that the lamina densa was 78.54 +/- 53.10 nm in line J4, the large variation reflecting the protrusions of the lamina densa, and 44.24 +/- 11.52 nm in line G20, compared with 33.74 +/- 9.96 nm in wild-type adult mice. Immunoelectron microscopy of wild-type mouse skin type XVIII collagen showed a polarized orientation in the BMs, with the C-terminal endostatin region localized in the lamina densa and the N terminus in average approximately 40 nm more on the dermal side. Type XVIII collagen was dispersed in the transgenic skin, suggesting that the transgene-derived endostatin fragment displaces the full-length collagen XVIII. This may impair the anchoring of the lamina densa to the dermis and thereby lead to loosening of the BMs, resembling the previously observed situation in collagen XVIII-null mice.
Mice lacking exon 3 of perlecan (Hspg2) gene were generated by gene targeting. Exon deletion does not alter the expression or the reading frame but causes loss of attachment sites for three heparan sulfate (HS) side chains. Hspg2(Delta 3 / Delta 3) mice are viable and fertile but have small eyes. Apoptosis and leakage of cellular material through the lens capsule are observed in neonatal lenses, and lenses degenerate within 3 weeks of birth. Electron microscopy revealed altered structure of the lens capsule through which cells had formed extensions. No kidney malfunction, such as protein uria, was detected in Hspg2(Delta 3 / Delta 3) mutant mice, nor were ultrastructural changes observed in the glomerular basement membranes (BMs). To achieve further depletion in the HS content of the BMs, Hspg2(Delta 3 / Delta 3) mice were bred with collagen XVIII null mice. Lens defects were more severe in the newborn Col18a1(-/-) x Hspg2(Delta 3 / Delta 3) mice and degeneration proceeded faster than in Hspg2(Delta 3 / Delta 3) mice. The results suggest that in the lens capsule, HS chains have a structural function and are essential in the insulation of the lens from its environment and in regulation of incoming signals.
The aim of the study was to investigate the effects of local treatment of rat eyes with D-penicillamine (PE) or D-penicillamine disulfide eye drops and their influence on the development of UV-induced lens opacities. 126 Brown Norway rats were divided into 14 groups to test the efficacy of different concentrations of the drugs. During the investigation period, slitlamp examinations and Scheimpflug measurements were performed. The post-mortem analysis comprised biochemical and histological investigations. This paper deals with the histological part of the study. A generally beneficial effect of the substances in question could not be found by means of histological methods. The best effect in relative terms was obtained by the use of 3.0% PE after a pretreatment of 7 days before starting UV irradiation. This result is in agreement with the evaluation of the Scheimpflug photography by microdensitometric image analysis.
We studied the handling and the potentials of three different cameras operating according to the Scheimpflug principle and which currently are commercially available. The examinations were performed with the cameras Topcon SL-45, Topcon SL-6E with cataract attachment and Zeiss SLC system. Pigmented Brown-Norway rats with ultraviolet-B-induced cataract were used as the examination model. The image characteristics of the three cameras can be summarized as follows: The Topcon SL-45 camera produces very sharp images with small distortion; the Tocpon SL-6E camera with cataract attachment has the advantage to record simultaneously a slit image and a retroillumination image on the same film frame, but the slit image is quite distorted at the vertical axis; as regards the Zeiss SLC system, the quality of the video image is not as good as a film negative; however, this camera offers a superimposed image to the observer for easy orientation, as for example with small animal eyes. In addition, the direct quality control of the image on the screen increases the reproducibility significantly. However, the slit image is quite distorted at the horizontal axis.
The purpose of this study was to determine: (1) which of the commonly used strains of laboratory rats and mice provide good models for human age-related cataract, and (2) whether long term caloric restriction, a regimen that prolongs both median and maximum life span in rodents, would also delay the time of appearance of this age-related pathology. Three strains of mice and two rat strains commonly used in laboratory work and maintained on either ad libitum (AL) or calorically restricted (CR) diets in the National Institutes of Aging and Diet Restriction colony were examined by slit lamp for age-related cataracts at four or more time points during their life spans. These strains were Brown Norway and Fischer 344 rats, and C57BL/6, (C57BL6 x DBA/2)F1 and (C57BL/6 x C3H)F1 mice. None of these strains develop congenital cataracts. Various stages of cataract were found in the great majority of these animals in old age. In both rat strains and one mouse strain the cataracts occurred after mid-life, were most advanced late in life, and were similar in locations and appearance to those in humans. In the two mouse strains in which some cataracts appeared as early as 10-14 months of age, previously identified genetic defects affecting the eye were probably involved in the early appearances. CR extended life spain in all five rat and mouse strains and also delayed both the time of first appearances and the subsequent increase in cataract severity over time in the four dark-eyed strains. CR did not delay cataract formation in the single albino rat strain studied. In summation: (1) commonly used strains of laboratory rats and mice that are free of congenital or early appearing cataracts due to genetic defects would appear to serve as appropriate models for human age-related cataract, (2) caloric restriction (CR) provides a protective effect, delaying development of cataracts in the dark-eyed mouse and rat strains, while also extending their life spans, (3) CR did not delay the development of lens damage in the nonpigmented eye of the single albino strain studied, although it extended life span.
To investigate whether posterior capsule opacification (PCO) morphology, visual acuity (VA) and self-assessed visual function correlate, and to compare perceived visual disabilities with those of cataract patients with corresponding VA.
Twenty-one patients with PCO were examined before capsulotomy. In adjunct to the ophthalmological examination, the patients completed a Catquest questionnaire and a digitized retroillumation image was acquired. The images were analysed with the Evaluation of Posterior Capsule Opacification (EPCO) program. Data for visual function were compared with data from the National Swedish Cataract Register (NCR).
The epco values were correlated with VA in the PCO eyes: the higher the epco score, the lower the VA. There were also correlations between the epco scores, satisfaction with vision, and perceived disabilities in daily life. Symptoms of glare were not significantly correlated with epco scores or with VA. Visual acuity in PCO eyes was better correlated with perceived disabilities and satisfaction with vision than VA in eyes with cataract.
There was a significant correlation between epco scores and VA and between epco scores and Catquest. Consequently, the morphological method was related to the self-assessed visual function. Patients with PCO seemed to have more disturbed visual function, as defined by Catquest, than cataract patients with the same VA.
Pseudoexfoliation (PEX) of the lens capsule is a well-known risk factor for open-angle glaucoma. Its prevalence is known to increase by age in the same way as prevalence of age-dependent cataract. In the present paper the prevalence of PEX varied from 8.5 to 13.2% increasing by age. Lens opacities were statistically significantly more common in PEX-positive than PEX-negative eyes. The importance of detecting exfoliation from the lens surface is discussed.
Scheimpflug photography has become the basic method for documentation of lens transparency changes in clinical and experimental ophthalmology, due to its high reproducibility. In animal cataract studies, the reproducibility is strongly influenced by the handling characteristics of the camera used, due to limited cooperation of the animal. The reproducibility of the Zeiss SLC system, which offers a direct quality control of the image on the video screen, was tested with 2 animal cataract models, the ultraviolet B (UVB)-induced cataract and the true diabetic cataract in the Brown-Norway rat. 10 rats each of the 2 cataract models and of an untreated control group were photographed in a random order on 3 occasions on the same day by the same photographer. Quality control and densitometry were performed by the same system operator, the measurement window was positioned standardly, coincident with the optical axis of the eye. Statistical comparison was carried out in the capsular layer, that is the area of initial cataract development in both models, and in the cortical layer, into which the diabetic cataract progresses during its later stages of development. The nuclear layer was also evaluated, but has no direct relation to one of the models employed. The results clearly indicate that the reproducibility is predominantly influenced by the homogeneity or inhomogeneity of the cataract model employed. The system operator and the photographer provided that they are well trained, have minor influence on the reproducibility of the Zeiss SLC system.
Ultraviolet (UV) filter photography with the Topcon SL-45 Scheimpflug camera has provided valuable informations about age-related and cataract-type-dependent changes in the spectral properties of the human lens. The present study deals with the same phenomenon in normal lenses of the Brown-Norway rat and in those with true diabetic and naphthalene cataracts. The lenses of all animals of the 3 groups were photographed at the middle and final examination of a 6-week experiment on Kodak Tri-X-pan ASA 400 black-and-white film, using visible light (xenon flash) and UV-filtered light (320-390 nm transmission) from the same light source for recording. The results clearly demonstrate that both cataract models exhibit characteristic fluorescence properties, different from each other and from normal rat lenses. The naphthalene cataract shows the most drastic increase in fluorescence in the cortex, compared to the increase in scattering with visible light. The versatility of the method in preclinical research and the versatility of the cataract models open new aspects of drug-related research in drug toxicity studies.