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BACKGROUND: To report a case of proliferative diabetic retinopathy (PDR) exhibiting the appearance of scintillating particles presumed to be crystallin inside the intravitreal cavity after laser photocoagulation.
METHODS: A 56-year-old male patient presented at our outpatient clinic after becoming aware of decreased vision in his right eye. Ocular examination performed at the patient\'s initial visit revealed a massive preretinal macular hemorrhage due to PDR in his right eye. Fundus fluorescein angiography revealed extensive retinal non-perfusion areas and neovascularization in both eyes. However, no opacity was observed in the intravitreal cavity of his left eye. Vitreous surgery was performed on the patient\'s right eye after ultrasonic phacoemulsification aspiration and intraocular lens implantation. Post surgery, the corrected VA in that eye improved from 0.1 to 1.0. In correlation with the treatment performed on the patient\'s right eye, we began panretinal photocoagulation on his left eye. Examination performed prior to the patient\'s third session of panretinal photocoagulation revealed a large number of scintillating particles in the posterior vitreous gel in front of the retina. Examination via slit-lamp microscopy revealed that the particles were of varied hues, and closely resembled a \'Christmas tree\' cataract. No posterior vitreous detachment was observed, and since these particles were situated as if captured in the posterior vitreous gel, no eye-movement-associated mobility of the particles was observed. Since the cloudiness was not severe enough to interfere with photocoagulation, additional photocoagulation was performed, and the patient is currently under observation. Six months have now passed since the fourth photocoagulation procedure was performed, and there has been no change in the state of the particles. Optical coherence tomography imaging revealed no change before and after the panretinal photocoagulation. The corrected VA in his left eye has remained at 1.0 during the postoperative follow-up period.
CONCLUSIONS: We speculate that the production of crystallin in the retina in this case was triggered by the photocoagulation procedure performed for diabetic retinopathy.

Phacolytic glaucoma is an open-angle glaucoma that occurs when lens proteins from hypermature cataracts seep through an intact anterior capsule and induce obstruction of the trabecular meshwork by inflammatory cells. We review the case of a 66-year-old man who presented with acute pain, a hypermature cataract, prominent anterior chamber crystals, and elevated intraocular pressure. After cataract surgery was performed, iridescent crystals were noted in the posterior chamber. Anterior chamber crystals have been associated with phacolytic glaucoma, but this is the first case demonstrating crystals in the posterior chamber as well.

BACKGROUND: Phacolytic glaucoma is induced by lens protein or macrophages that have leaked through a macroscopically intact anterior lens capsule. Here, we report a case of phacolytic glaucoma with anterior lens capsule disruptions visualized by scanning electron microscopy (SEM).
METHODS: A 71-year-old man was referred to our institute for increased intraocular pressure (IOP) in the right eye. Slit-lamp biomicroscopic examination revealed corneal edema, the presence of inflammatory cells and iridescent crystalline in the anterior chamber, and a hypermature cataract in the right eye. Despite treatment with topical glaucoma medication (0.15% brimonidine, 1% brinzolamide/0.5% timolol, and 0.03% bimatoprost) and systemic mannitol, his IOP remained uncontrolled. Light microscopy was used to examine the aqueous humor obtained via anterior chamber paracentesis and the anterior lens capsule obtained via intracapsular cataract extraction (ICCE), which revealed that the anterior lens capsule was intact. However, SEM revealed full-thickness disruptions in the anterior lens.
CONCLUSIONS: This is the first reported case of phacolytic glaucoma with disruptions of the anterior lens capsule confirmed by SEM.

While amyloid structures have been well characterised in a medical context, there is increasing interest in studying amyloid-like aggregates in other areas, such as food science and nanomaterials. Several proteins relevant to food processing, including serum albumen, lactoglobulin, lysozyme, ovalbumin, casein, and soy protein isolate have been shown to form fibrillar structures under both physiological and non-physiological conditions. These structures are likely to contribute to the structural characteristics of the final food product. In a biotechnological context, proteins such as insulin and eye lens crystallins can be induced to form amyloid structures which can subsequently be used in biotechnology. One example of this is the use of amyloid fibrils as a scaffold for the immobilisation of enzymes. Another current interest in amyloid fibrils is as a storage form for peptide hormones, including insulin, glucagon and calcitonin. Here, we give an overview of a selection of well characterised proteins that have been studied outside the context of disease.

A 62-year-old female visited our clinic with progressively decreased vision in both eyes beginning 12 years prior. Idiopathic corneal opacity in all layers of the cornea was found in both eyes. One year later, we performed penetrating keratoplasty on the undiagnosed right eye. During post-surgical follow-up, corneal edema and stromal opacity recurred, and penetrating keratoplasty was performed two more times. The patient\'s total serum protein level, which had previously been normal, was elevated prior to the final surgery. She was diagnosed with monoclonal gammopathy of undetermined significance. We made a final diagnosis of monoclonal gammopathy-associated crystalline keratopathy after corneal biopsy. Monoclonal gammopathy-associated crystalline keratopathy is difficult to diagnose and may lead to severe visual loss. A systemic work-up, including serologic tests like serum protein or cholesterol levels, is needed in patients with unexplainable corneal opacity.

Lens development is an excellent model for genetic and biochemical studies of embryonic induction, cell cycle regulation, cellular differentiation and signal transduction. Differentiation of lens is characterized by lens-preferred expression and accumulation of water-soluble proteins, crystallins. Crystallins are required for light transparency, refraction and maintenance of lens integrity. Here, we review mechanisms of lens-preferred expression of crystallin genes by employing synergism between developmentally regulated DNA-binding transcription factors: Pax6, c-Maf, MafA/L-Maf, MafB, NRL, Sox2, Sox1, RARbeta/RXRbeta, RORalpha, Prox1, Six3, gammaFBP-B and HSF2. These factors are differentially expressed in lens precursor cells, lens epithelium and primary and secondary lens fibers. They exert their function in combination with ubiquitously expressed factors (e.g. AP-1, CREB, pRb, TFIID and USF) and co-activators/chromatin remodeling proteins (e.g. ASC-2 and CBP/p300). A special function belongs to Pax6, a paired domain and homeodomain-containing protein, which is essential for lens formation. Pax6 is expressed in lens progenitor cells before the onset of crystallin expression and it serves as an important regulatory factor required for expression of c-Maf, MafA/L-Maf, Six3, Prox1 and retinoic acid signaling both in lens precursor cells and the developing lens. The roles of these factors are illustrated by promoter studies of mouse alphaA-, alphaB-, gammaF- and guinea pig zeta-crystallins. Pax6 forms functional complexes with a number of transcription factors including the retinoblastoma protein, pRb, MafA, Mitf and Sox2. We present novel data showing that pRb antagonizes Pax6-mediated activation of the alphaA-crystallin promoter likely by inhibiting binding of Pax6 to DNA.

Among lens crystallins, gamma-crystallins are particularly sensitive to oxidation, because of their high amount of Cys and Met residues. They have the reputation to induce, upon ageing, lens structural modifications leading to opacities. A combination of small angle X-ray scattering and chromatography was used to study the oxidation of gamma-crystallins. At pH 7.0, all the gamma-crystallins under study were checked to have the same structure in solution. Under gentle oxidation conditions at pH 8.0, human gammaS (hgammaS) and bovine gammaS (bgammaS) formed disulfide-linked dimers, whereas the other bgamma-crystallins did not. Cys20 was shown to be responsible for dimer formation since the C20S mutant only formed monomers. The hgammaS dimers were stable for weeks and did not form higher oligomers. In contrast, monomeric gammaS-crystallins freshly prepared at pH 8.0, and submitted to more drastic oxidation by X-ray induced free radicals, were rapidly transformed into higher oligomers. So, only extensive oxidation causing partial unfolding could be detrimental to the lens and linked to cataract formation. The gammaS-crystallins lack the temperature-induced opacification observed with the other gamma-crystallins and known as cold cataract. The oxidation-induced associative behaviour and cold cataract are therefore demonstrated to be uncoupled.

It is established that the diverse, multifunctional crystallins are responsible for the optical properties of the cellular, transparent lens of the complex eyes of vertebrates and invertebrates. Lens crystallins often differ among species and may be enzymes or stress proteins. I present here the idea that abundant water-soluble enzymes and other proteins may also be used for cellular transparency in the epithelial cells and, possibly, stromal keratocytes of the cornea. Aldehyde dehydrogenases and transketolase are among the putative \"corneal crystallins\" in mammals, and gelsolin may be a corneal crystallin in the zebrafish. In invertebrates, the glutathione S-transferase-related S-crystallins of the lens appear to be used also as corneal crystallins in the squid, and an aldehyde dehydrogenase-related protein is the crystallin in the lens and, possibly, cornea of the scallop. The use of abundant, taxon-specific water-soluble proteins as crystallins for cellular transparency in the cornea would provide a new conceptual link between this tissue and the lens.

The six closely related and clustered rat gamma-crystallin genes, the gammaA- to gammaF-crystallin genes, are simultaneously activated in the embryonic lens but differentially shut down during postnatal development with the gammaB-crystallin gene, the last one to be active. We show here that developmental silencing of the gammaD-crystallin promoter correlates with delayed demethylation during lens fiber cell differentiation. Methylation silencing of the gammaD-crystallin promoter is a general effect and does not require the methylation of a specific CpG, nor does methylation interfere with factor binding to the proximal activator. In later development, the gammaD-crystallin promoter is also shut down earlier by a repressor that footprints to the -91/-78 region. A factor with identical properties is present in brain. Hence, a ubiquitous factor has been recruited as a developmental regulator by the lens. All gamma-crystallin promoters tested contain upstream silencers, but at least the gammaB-crystallin silencer is distinct from the gammaD-crystallin silencer. The gamma-crystallin promoters were found to share a proximal activator (the gamma-box; around -50), which behaves as a MARE. The gammaB-box is recognized with much lower avidity than the gammaD-box. By swapping elements between the gammaB- and the gammaD-crystallin promoter, we show that activation by the gammaB-box requires a directly adjacent -46/-38 AP-1 consensus site. These experiments also uncovered another positive element in the gammaD-crystallin promoter, around -10. In the context of the gammaD-crystallin promoter, this element is redundant; in the context of the gammaB-crystallin promoter, it can replace the -46/-38 element.