Lens Tissue Research Articles

Proteomic analysis of posterior capsular plaques in congenital unilateral cataract.

To obtain insights on the protein composition of posterior capsular plaques (PCP) in congenital unilateral cataract with anterior vitreolenticular interface dysgenesis (AVLID). Posterior capsular plaque's were collected during surgery in children presenting with congenital unilateral cataract. Surgeries were analysed focusing on the type of cataract, the integrity of the posterior capsule after peeling the PCP and the presence of vitreolenticular adherences when performing primary posterior capsulorhexis. Proteome analysis was performed on the collected PCPs. Posterior capsular plaques collection and proteome analysis were feasible from four children presenting with unilateral idiopathic congenital cataract and AVLID. A large portion of the proteins found in the PCPs was similar to the proteins known to be present in lens epithelial cells and fibres. Proteins like vimentin, fibronectin, collagen type I, collagen type VI and lumican were also found, which typically are present in mesenchymal tissue but not in lens tissue or capsule. Posterior capsular plaques in cases of unilateral idiopathic congenital cataract of the AVLID type present a protein composition of mainly proteins found in lens epithelial cells and fibres. Some proteins however are a specific for lens tissue and are typically seen in mesenchymal tissue.

The lens internal microcirculation system delivers solutes to the lens core faster than would be predicted by passive diffusion.

It has been proposed that optical properties of the lens are actively maintained by an internal microcirculation system that utilizes ionic and fluid fluxes to deliver nutrients to deeper regions of the lens tissue via the extracellular space faster than would occur by passive diffusion alone. To test this hypothesis, we utilized a range of commercially available magnetic resonance imaging (MRI) reagents of varying molecular sizes that served as tracers of extracellular solute delivery. The penetration of these tracers into bovine lenses incubated in the absence and presence of solutions that inhibit the microcirculation was monitored in real time over a 4-h period using T1-weighted MRI. We found that only the smaller contrast agents were delivered to the core of the lens and that the rate of solute penetration was significantly faster than that calculated simple diffusion. Next, the lenses were first incubated in either high extracellular K+ to depolarize the lens potential or ouabain to inhibit the Na+ pump. These two perturbations are known to inhibit the circulating ionic and fluid fluxes that are proposed to drive solute delivery into the lens core. Both perturbations inhibited the delivery of the extracellular tracer molecules to the lens core. Our findings suggest that the microcirculation system can potentially be harnessed to deliver exogenous antioxidants to the lens core to afford mature fiber cells protection against oxidative damage that ultimately manifests as age-related nuclear cataract.

Numerical Analysis of the Thermal Interaction of Cell Phone Radiation with Human Eye Tissues

Introduction: The present study aimed to present a numerical analysis of the penetration depth, specific absorption rate (SAR), and temperature rise in various eye tissues with varying distance between radiation source and exposed human eye tissues (i.e., cornea, posterior chamber, anterior chamber, lens, sclera, vitreous humor, and iris) at frequencies of 900 and1800 MHz. Materials and Methods: A theoretical model was proposed based on the tissue dielectric and thermal properties, Maxwell equations, Joules law of heating, and microscopic form of Ohm's law to find the realistic situation of the cell phone radiation interaction with various human eye tissues. Results: According to the results, the anterior chamber had the highest temperature rise, compared to the vitreous, sclera, lens, cornea, and posterior chamber. By assuming the distance of 5 cm and exposure time of 30 min, the maximum rise in temperature for the anterior chamber was estimated to be 1.2°C and 2.2°C for 900 and 1,800 MHz frequencies, respectively. Conclusion: As the findings indicated, the anterior chamber had the maximum rise in temperature, compared to other investigated tissues. This could be due to the disposal of excess heat by the perfusion of the blood in the vitreous, posterior chamber, sclera, and lens tissues and the cooling effects produced due to convection/conduction in the cornea tissue. However, the anterior chamber tissue had no such mechanism for heat disposal.

BNIP3L/NIX is required for elimination of mitochondria, endoplasmic reticulum and Golgi apparatus during eye lens organelle-free zone formation

The formation and life-long growth of the ocular lens depends on the continuous differentiation of lens epithelial cells into lens fiber cells. To achieve their mature structure and transparent function, newly formed lens fiber cells undergo a series of cellular remodeling events including the complete elimination of cellular organelles to form the lens organelle-free zone (OFZ). To date, the mechanisms and requirements for organelle elimination by lens fiber cells remain to be fully elucidated. In previous studies, we detected the presence of mitochondria contained within autophagolysosomes throughout human and chick lenses suggesting that proteins targeting mitochondria for degradation by mitophagy could be required for the elimination of mitochondria during OFZ formation. Consistently, high-throughput RNA sequencing of microdissected embryonic chick lenses revealed that expression of a protein that targets mitochondria for elimination during erythrocyte formation, called BCL2 interacting protein 3-like (BNIP3L/NIX), peaks in the region of lens where organelle elimination occurs. To examine the potential role for BNIP3L in the elimination of mitochondria during lens fiber cell remodeling, we analyzed the expression pattern of BNIP3L in newborn mouse lenses, the effect of its deletion on organelle elimination and its co-localization with lens organelles. We demonstrate that the expression pattern of BNIP3L in the mouse lens is consistent with it playing an important role in the elimination of mitochondria during lens fiber cell organelle elimination. Importantly, we demonstrate that deletion of BNIP3L results in retention of mitochondria during lens fiber cell remodeling, and, surprisingly, that deletion of BNIP3L also results in the retention of endoplasmic reticulum and Golgi apparatus but not nuclei. Finally, we show that BNIP3L localizes to the endoplasmic reticulum and Golgi apparatus of wild-type newborn mouse lenses and is contained within mitochondria, endoplasmic reticulum and Golgi apparatus isolated from adult mouse liver. These data identify BNIP3L as a novel requirement for the elimination of mitochondria, endoplasmic reticulum and Golgi apparatus during lens fiber cell remodeling and they suggest a novel function for BNIP3L in the regulation of endoplasmic reticulum and Golgi apparatus populations in the lens and non-lens tissues.

Teleost and elasmobranch eye lenses as a target for life-history stable isotope analyses.

Incrementally grown, metabolically inert tissues such as fish otoliths provide biochemical records that can used to infer behavior and physiology throughout the lifetime of the individual. Organic tissues are particularly useful as the stable isotope composition of the organic component can provide information about diet, trophic level and location. Unfortunately, inert, incrementally grown organic tissues are relatively uncommon. The vertebrate eye lens, however, is formed via sequential deposition of protein-filled fiber cells, which are subsequently metabolically inert. Lenses therefore have the potential to serve as biochemical data recorders capturing life-long variations in dietary and spatial ecology. Here we review the state of knowledge regarding the structure and formation of fish eye lenses in the context of using lens tissue for retrospective isotopic analysis. We discuss the relationship between eye lens diameter and body size, describe the successful recovery of expected isotopic gradients throughout ontogeny and between species, and quantify the isotopic offset between lens protein and white muscle tissue. We show that fish eye lens protein is an attractive host for recovery of stable isotope life histories, particularly for juvenile life stages, and especially in elasmobranchs lacking otoliths, but interpretation of lens-based records is complicated by species-specific uncertainties associated with lens growth rates.

In vitro method for determining corneal tissue damage due to contact lens frictional forces

Purpose: Mechanical interactions between a contact lens and ocular tissue can result in damage to corneal epithelial tissue and may affect comfort. These mechanical interactions cannot be characterized solely by a coefficient of friction (CoF) value since the frictional force on the ocular tissue, which can be responsible for cell damage, depends on a normal force that will be a function of several variables; such as the upper eyelid pressure, lens design, and ocular surface shape. The efforts described here were undertaken to find a tribological metric that correlates with corneal epithelial cell damage.

A novel in-vitro complete anterior eye model: Preliminary results

Purpose: Previous research has established the viability of maintaining, independently, either corneal or crystalline lens tissue physiologically stable for a period of ∼10 days. This study aimed to design and evaluate a novel complete anterior eye model that combines these two structures, allowing anterior chamber evaluation.

Evaluation of the effects of saffron aqueous extract on oxidative stress in the lens of streptozotocin-induced diabetic rats

Background: Multiple-organ failure is the main cause of disability and death in diabetes mellitus. Imbalance in oxidative status is responsible for major diabetic complications and multiple-organ failure including blindness. Recently, plants with potential antioxidant properties have been used to manage hyperglycemia in diabetes. This study was undertaken to evaluate the beneficial effects of saffron aqueous extract (SAE) administration in streptozotocin (STZ)-induced diabetic rats by evaluation of oxidative stress parameters in the eye lens. Methods: Thirty-two adult rats were randomly divided into four groups: normal control (I), saffron control (II), diabetic control (III), and saffron treated (IV). Diabetes was induced in animals by a single intraperitoneal (i.p.) injection of STZ (60 mg/kg body weight). Three days after STZ administration, diabetes was confirmed by measuring fasting blood glucose. At this time, groups II and IV were treated with SAE (200 mg/kg body weight) for a total of 5 doses, and then weekly from the 7th day after STZ injection. At the end of study, fasting blood glucose levels, activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as malondialdehyde (MDA) content were determined in the lens tissues. Results: In addition to the effects of SAE on blood glucose, SAE was effective on the enzymatic antioxidant defense system. The level of antioxidant enzymes (SOD, CAT, and GPx) decreased while there was an increase in the levels of MDA in the lens tissues of diabetic control rats, as compared to normal control rats. SAE could be modulating the changes in these parameters that are induced by diabetes. Conclusion: The results of the present study demonstrate that SAE is able to control blood glucose and thus may be useful in delaying the complicated effects of diabetes, such as clouding of the eyes’ lens due to the antioxidant effect of SAE.

Resolution enhancement for fiber bundle imaging using maximum a posteriori estimation.

We propose a new framework to jointly improve spatial resolution and remove fixed structural patterns for coherent fiber bundle imaging systems, based on inverting a principled forward model. The forward model maps a high-resolution representation to multiple images modeling random probe motions. We then apply a point spread function to simulate low-resolution figure bundle image capture. Our forward model also uses a smoothing prior. We compute a maximum a posteriori (MAP) estimate of the high-resolution image from one or more low-resolution images using conjugate gradient descent. Unique aspects of our approach include (1)supporting a variety of possible applicable transformations; (2)applying principled forward modeling and MAP estimation to this domain. We test our method on data synthesized from the USAF target, data captured from a transmissive USAF target, and data from lens tissue. In the case of the USAF target and 16 low-resolution captures, spatial resolution is enhanced by a factor of 2.8.

The effects of mechanical strain on mouse eye lens capsule and cellular microstructure.

The mouse eye lens was used as a model for multiscale transfer of loads. In the lens, compressive strain is distributed across specific lens tissue microstructures, including the extracellular capsule, as well as the epithelial and fiber cells. The removal of high loads resulted in complete recovery of most, but not all, microstructures.

Role of innate immunity and oxidative stress in steroid-induced cataracts in developing chick embryos

Purpose: The exact etiopathogenesis of steroid-induced cataracts (SIC) is not known. Although oxidative stress is one of the most acceptable hypotheses, the exact molecular events in steroid-induced oxidative events in the lens need to be clarified. In addition, to the best of our knowledge, the innate immune system components in SIC formation have not been studied previously. The aim of the present study was to study the oxidative system and the innate immune system components in the cataractous lenses of a developing chick embryo SIC model.Materials and methods: The study included 20 specific pathogen-free (SPF) fertilized eggs divided into two groups, with one hydrocortisone (HC)-treated group (G1) and one non-HC-treated control group (G2). On the 15th day of incubation, the SPF eggs in the two groups were removed from the incubator; HC was injected into G1, and phosphate-buffered saline (PBS) was injected into G2 using insulin injectors into the chorioallantoic membrane. On day 17, all of the chick embryos were removed from the eggs, and all lens and liver tissues were dissected from the embryos. Cataract formation was evaluated in all lenses, and total antioxidant status (TAS), total oxidant status (TOS), reduced glutathione (GSH), oxidized glutathione (GSSG), interleukin-6 (IL-6), and interleukin-1β (IL-1β) levels were measured in all lens and liver tissues.Results: The lenses in the SIC group had lower levels of GSH, GSSG, TAS, and IL-6 (p = 0.016, 0.022, 0.000, 0.000, respectively), and higher levels of TOS (p = 0.000) than the control group. Furthermore, the liver tissues in the SIC group had decreased levels of TAS and IL-6, and increased levels of TOS compared to the control tissues (p = 0.000). Although the IL-1β levels in the lens and liver tissues in the HC-induced cataract group were lower than in the control group, these differences were not statistically significant. In addition, the GSH levels in the liver tissues did not statistically differ between the two groups despite the significant GSH difference in the lens tissues.Conclusions: Steroid therapy causes a decrease in GSH, GSSG, and TAS levels and an increase in TOS levels in lens tissues, which means there is increased oxidative stress and decreased antioxidant defence. Furthermore, lenses with SIC have lower IL-6 levels compared to non-cataractous lenses. The interaction between lenticular IL-6 and antioxidant defence needs to be further studied.

Protective effect of Pterocarpus marsupium bark extracts against cataract through the inhibition of aldose reductase activity in streptozotocin-induced diabetic male albino rats.

The present study was aimed to investigate the protective effect of Pterocarpus marsupium bark extracts against cataract in streptozotocin-induced diabetic male albino rats. Aldose reductase is a key enzyme in the intracellular polyol pathway, which plays a major role in the development of diabetic cataract. Rats were divided into five groups as normal control, diabetic control, and diabetic control treated with different concentrations of Pterocarpus marsupium bark extracts. Presence of major constituents in Pterocarpus marsupium bark extract was performed by qualitative analysis. Body weight changes, blood glucose, blood insulin, and reduced glutathione (GSH) and aldose reductase mRNA and protein expression were determined. Rat body weight gain was noted following treatment with bark extracts. The blood glucose was reduced up to 36% following treatment with bark extracts. The blood insulin and tissue GSH contents were substantially increased more than 100% in diabetic rats following treatment with extracts. Aldose reductase activity was reduced up to 79.3% in diabetic rats following treatment with extracts. Vmax, Km, and Ki of aldose reductase were reduced in the lens tissue homogenate compared to the diabetic control. Aldose reductase mRNA and protein expression were reduced more than 50% following treatment with extracts. Treatment with Pterocarpus marsupium bark was able to normalize these levels. Taking all these data together, it is concluded that the use of Pterocarpus marsupium bark extracts could be the potential therapeutic approach for the reduction of aldose reductase against diabetic cataract.

Myo/Nog cells are present in the ciliary processes, on the zonule of Zinn and posterior capsule of the lens following cataract surgery

Myo/Nog cells, named for their expression of MyoD and noggin, enter the eye during early stages of embryonic development. Their release of noggin is critical for normal morphogenesis of the lens and retina. Myo/Nog cells are also present in adult eyes. Single nucleated skeletal muscle cells designated as myofibroblasts arise from Myo/Nog cells in cultures of lens tissue. In this report we document the presence of Myo/Nog cells in the lens, ciliary body and on the zonule of Zinn in mice, rabbits and humans. Myo/Nog cells were rare in all three structures. Their prevalence increased in the lens and ciliary body of rabbits 24 h following cataract surgery. Rabbits developed posterior capsule opacification (PCO) within one month of surgery. The number of Myo/Nog cells continued to be elevated in the lens and ciliary body. Myo/Nog cells containing alpha smooth muscle actin and striated muscle myosin were present on the posterior capsule and overlaid deformations in the capsule. Myo/Nog cells also were present on the zonule fibers and external surface of the posterior capsule. These findings suggest that Myo/Nog contribute to PCO and may use the zonule fibers to migrate between the ciliary processes and lens.

Crim1 is required for maintenance of the ocular lens epithelium

The development and growth of the vertebrate ocular lens is dependent on the regulated proliferation of an anterior monolayer of epithelial cells, and their subsequent differentiation into elongate fiber cells. The growth factor rich ocular media that bathes the lens mediates these cellular processes, and their respective intracellular signaling pathways are in turn regulated to ensure that the proper lens architecture is maintained. Recent studies have proposed that Cysteine Rich Motor Neuron 1 (Crim1), a transmembrane protein involved in organogenesis of many tissues, might influence cell adhesion, polarity and proliferation in the lens by regulating integrin-signaling. Here, we characterise the lens and eyes of the Crim1KST264 mutant mice, and show that the loss of Crim1 function in the ocular tissues results in inappropriate differentiation of the lens epithelium into fiber cells. Furthermore, restoration of Crim1 levels in just the lens tissue of Crim1KST264 mice is sufficient to ameliorate most of the dysgenesis observed in the mutant animals. Based on our findings, we propose that tight regulation of Crim1 activity is required for maintenance of the lens epithelium, and its depletion leads to ectopic differentiation into fiber cells, dramatically altering lens structure and ultimately leading to microphthalmia and aphakia.

A Simple Method of Cataract Induction in Adult Zebrafish.

We have developed a simple method for the induction of cataracts in adult zebrafish using hydrogen peroxide. Our method uses a corneal puncture followed by intraocular injection of hydrogen peroxide into the anterior chamber. The procedure can be done rapidly, forming a highly opaque cataract almost immediately, and fish recover quickly. The optical clarity of the lens is gradually regained over time, showing the innate ability of zebrafish to regenerate healthy lens tissue. This technique provides a simple in vivo system with which to assess mutant strains or targeted disruptions to genes expressed in the lens.

Cataracts Contain Amyloid β-Sheets: A 2D IR Study of Human Cataract Tissue

Age-related cataract disease affects the sight of more than 50% of Americans over the age of 80. Cataracts are caused by the aggregation of crystallin proteins in the eye lens, leading to blurred vision, but there is not a clear understanding of the molecular structure changes that lead to the disease. In vitro, crystallin proteins form both amorphous aggregates and amyloid fiber structures, depending on the solution conditions; however, there is little evidence that the aggregates in cataractous lens tissue contain amyloid deposits. This talk will present two-dimensional infrared (2D IR) spectra of natural human cataract lens tissue collected from a deceased individual. 2D IR spectra distinguish between the native β-sheet structures of crystallin lens proteins and their amyloid fiber aggregates through a distinct diagonal peak as well as an off-diagonal cross peak. Control experiments are presented on in vitro crystallin proteins, pig lens tissue, and human non-cataract lens tissue for comparison with diagnosed cataract lens tissue spectra. The 2D IR signatures of amyloid β-sheets are clearly observed in cataract tissue. We also show that exposure to UV radiation, a significant risk factor for age-related cataract disease, produces signatures of amyloid formation in healthy eye lens tissue. These results establish cataracts as an amyloid disease, and have implications for the recent development of small molecules that appear to dissolve cataracts in animal models.

A model for investigating developmental eye repair in Xenopus laevis

Vertebrate eye development is complex and requires early interactions between neuroectoderm and surface ectoderm during embryogenesis. In the African clawed frog, Xenopus laevis, individual eye tissues such as the retina and lens can undergo regeneration. However, it has been reported that removal of either the specified eye field at the neurula stage or the eye during tadpole stage does not induce replacement. Here we describe a model for investigating Xenopus developmental eye repair. We found that tailbud embryos can readily regrow eyes after surgical removal of over 83% of the specified eye and lens tissues. The regrown eye reached a comparable size to the contralateral control by 5 days and overall animal development was normal. It contained the expected complement of eye cell types (including the pigmented epithelium, retina and lens), and is connected to the brain. Our data also demonstrate that apoptosis, an early mechanism that regulates appendage regeneration, is also required for eye regrowth. Treatment with apoptosis inhibitors (M50054 or NS3694) blocked eye regrowth by inhibiting caspase activation. Together, our findings indicate that frog embryos can undergo successful eye repair after considerable tissue loss and reveals a required role for apoptosis in this process. Furthermore, this Xenopus model allows for rapid comparisons of productive eye repair and developmental pathways. It can also facilitate the molecular dissection of signaling mechanisms necessary for initiating repair.

Ex vivo and in silico Molecular Docking Studies of Aldose Reductase Inhibitory Activity of Apigenin from Morus indica L.

Objective: An investigation on Aldose Reductase Enzyme (ALR) inhibitory activity of apigenin (API) isolated from Morus indica L. was evaluated by ex vivo and molecular docking studies. Materials and Methods: The inhibitory efficacy of API from M. indica was evaluated against ALR in lens tissue of mice by ex vivo and their binding mechanism through molecular docking was carried out by AutoDock. Results: The API (10-50 µg mL-1) concentration exhibited significant inhibition (p ≤ 0.05) of ALR enzyme in a dose dependent manner with IC50 value of 39.23 µg mL-1. The positive control aminoguanidine (AG) at 10 mM inhibited 42.96% of ALR. The molecular docking studies revealed that API showed better binding energy (-9.15 kJ mol-1) when compared to AG (-3.78 kJ mol1 ). Molecular interaction analysis showed that API interrupts the proton donation mechanism which is necessary for the catalytic activity of ALR by forming H-bond with Trp20 (proton donor). Conclusion: The ALR inhibition potential offered by API was further confirmed through molecular docking studies. The present findings support the pharmacological application of API for the treatment of diabetes cataract. Key words: Mulberry, Antiglycation, Retinopathy, Eye lens.

Robotic Scanning Device for Intraoperative Thyroid Gland Endomicroscopy.

Probe-based confocal laser endomicroscopy has a high potential to be a promising tool that can provide intraoperative high-resolution in vivo morphological imaging at cellular and subcellular levels for thyroidectomy, and allow real-time assessment of tumor margins. However, the typical images acquired with this technique cover a very small area limited by the field of view of the probe, accompanied by tissue deformation and inconsistent probe-tissue contact when operated manually. In this paper, a novel compact robotic device for large area scanning has been developed. The device can scan a large surface in a spiral trajectory by rotating the tip frame along the spiral groove of the base frame. The fiber Bragg grating sensor with a passive linear structure is used to detect and maintain a stable probe-tissue contact force during scanning. An active linear actuation is also integrated for adjusting the probe-tissue contact level prior to each scan. Results demonstrate that the scanning device ensures a suitable probe-tissue contact force and compensates for simulated hand tremor. Mosaicing results of lens tissue paper and porcine belly tissue with both bench and hand-held experiments show the effectiveness and usability of the device, demonstrating the potential clinical value of the system.

The Effects of Saffron (Crocus sativus) Aqueous Extract on TNF-α Levels in Liver, Kidney, and Lens Tissues of Diabetic Rats

The Effects of Saffron (Crocus sativus) Aqueous Extract on TNF-α Levels in Liver, Kidney, and Lens Tissues of Diabetic Rats