The involvement of calpains in opacification induced by Ca2+-overload in ovine lens culture

Objective To investigate biochemical changes accompanying Ca²⁺-induced lens opacification and the possible role of calpain activation in opacification within an ovine lens culture system. Methods Sheep lenses were cultured in minimal media. Lens opacification was induced by exposure to the Ca²⁺ ionophore, ionomycin, and graded by digital image analysis. Cell viability was estimated by the release of lactate dehydrogenase into the culture medium. Opaque lenses were fixed and stained for a microscopic view of the lens structural changes. Ionic changes in the lens were measured by atomic absorption spectroscopy. Calpain activation was determined by zymography on casein gels and proteolysis was investigated by SDS–polyacrylamide gel electrophoresis (SDS–PAGE), two-dimensional gel electrophoresis (2DE) and Western blotting. The calpain inhibitor, SJA6017, was used to investigate the involvement of calpains in lens opacification. Results Treatment of cultured ovine lenses with ionomycin increased total lens Ca²⁺ concentration and caused the cortical region of the lens to become opaque. Addition of the Ca²⁺ chelator, EGTA, inhibited the ionomycin-induced changes. Progress of opacification correlated with the death of lens cells and lens swelling in differentiating fiber cells. Autolysis of calpain 2, following ionomycin treatment, suggested activation of this protease. 2DE revealed that the ionomycin did not result in substantial proteolysis of the crystallins. However, Western blotting revealed significant breakdown of the cytoskeletal proteins, spectrin and vimentin. The pattern of the breakdown products was consistent with calpain proteolytic activity. SJA6017 retarded the cortical opacity induced by Ca²⁺-overload in the ovine lens. Conclusion The ovine lens with Ca²⁺-induced opacification by ionomycin is associated with calpain activation and the subsequent proteolysis of cytoskeletal proteins. These events could be initial factors contributing to cell death and the loss of lens transparency which occurs in this ovine model of cataractogenesis. The ovine model supports the hypothesis that cytoskeletal proteins and Ca²⁺ homeostasis play an important role in maintaining lens transparency.     

Intraocular sarcoma associated with lens capsule rupture and persistent hyperplastic primary vitreous in a dog

This case report describes the clinical findings and ocular pathology in an adult Golden Retriever diagnosed with an intraocular sarcoma. Nineteen s prior to diagnosis with a lens capsule rupture and intraocular sarcoma, the dog was diagnosed with persistent hyperplastic primary vitreous and uveitis based on clinical signs and the ultrasonographic appearance of the eye. Two years after enucleation, there was no evidence of metastatic spread of the sarcoma. The immunohistochemical characteristics of the tumor as well as the limitations and supportive evidence used in attempting to identify the histogenesis of the tumor are outlined.     

Traumatic phacocele in an American Miniature Horse

An 18‐year‐old American Miniature Horse mare was presented with a complaint of a scleral swelling affecting the right eye and a history of suspected trauma 6 weeks prior to evaluation. Clinical findings included severe blepharospasm, a bulbous swelling of the dorsotemporal bulbar conjunctiva, and phthisis bulbi. Ocular ultrasound was recommended but declined. Enucleation was elected for the blind, painful eye and was performed standing. Gross and histopathologic examinations of the globe were consistent with extrusion of the lens to the episcleral space, which is classified as a traumatic phacocele when associated with naturally occurring trauma. The location of lens entrapment suggested globe rupture occurred at the limbus, which is described as one of the weakest points of the equine globe. Subconjunctival dislocation of the lens and development of a traumatic phacocele should be considered as a differential diagnosis for horses presenting with subconjunctival masses, apparent aphakia, and historical trauma.     

CASE REPORT: Iridociliary melanoma with secondary lens luxation: distinctive findings in a long‐horned cowfish (Lactoria cornuta)

This report describes a long‐horned cowfish, which was diagnosed with buphthalmia and lens sub‐luxation in the right eye, conditions that progressed to complete anterior lens luxation and secondary keratoconus. Three months after the initial evaluation, a pigmented mass was observed protruding from the vitreous. An enucleation was performed under general anesthesia. Ocular histopathology revealed an iridociliary melanoma. Reports of intraocular melanomas are extremely rare in fish. To the authors’ knowledge, this is the first report of an iridociliary melanoma that led to buphthalmia, lens luxation, and keratoconus in a fish. Histological findings of lens luxation are also demonstrated. Due to the presence of a complex suspensory apparatus involving the teleost lens, this report speculates that lens luxation is a more devastating disease process in teleosts than in mammals.     

茶黄素对高糖诱导的人晶状体上皮细胞氧化损伤的影响

研究茶黄素(Theaflavin,TF)对高糖(High glucose,HG)诱导的人晶状体上皮细胞(Human lens epithelial cells,HLECs)氧化损伤的影响。采用体外培养人晶状体上皮细胞,用葡萄糖诱导细胞成氧化损伤模型,外加一定浓度的茶黄素干预,比色法检测细胞体内SOD、CAT、GSH-Px、MDA活力和含量的变化。结果表明相对于正常培养的细胞,高糖诱导细胞体内SOD、CAT、GSH的活性降低,MDA含量上升;加入茶黄素后,提高了细胞内SOD、CAT、GSH-Px的活力,降低了细胞内MDA的含量,与模型组细胞相比,具有显著差异(P0.01)。     

茶黄素对葡萄糖诱导的人晶状体上皮细胞 一氧化氮合成的影响

为探明茶黄素–3,3'–双没食子酸酯(TFDG)对人晶状体上皮细胞SRA01/04(Human lens epithelial cells,HLECs SRA01/04)的保护作用,采用MTT法建立高浓度葡萄糖(HG)诱导的HLECs损伤模型,同时观察HLECs细胞形态的变化。用不同浓度(4、8、16、64、32、64、128、256、512μmol/L)TFDG处理HLECs损伤细胞,采用化学比色法和硝酸还原法测定HLECs内一氧化氮(NO)的含量和一氧化氮合酶(NOS)的活性。结果表明:高浓度葡萄糖可以抑制人晶状体上皮细胞生长,用于HLECs损伤模型诱导的最佳葡萄糖浓度为50 mmol/L,最佳诱导时间为24 h;与未经处理的模型细胞相比,经浓度为16~64μmol/L TFDG处理的模型细胞的存活率显著提高(P0.05);各个浓度的TFDG能极显著降低模型细胞内NOS的活性,极显著减少NO的合成(P0.01),且呈浓度依赖性。以上结果表明,TFDG对高浓度葡萄糖诱导的HLECs细胞损伤具有较好的保护作用。