Showing papers in "Current Eye Research in 2006"
TL;DR: This review focuses on GSH and two key enzymes, glutathione reductase and glucose-6-phosphate dehydrogenase in lens, cornea, and retina, suggesting that the same enzyme systems are present in all tissues of the eye to generate NADPH and to maintain gluthatione in the reduced form.
Abstract: Glutathione and the related enzymes belong to the defence system protecting the eye against chemical and oxidative stress. This review focuses on GSH and two key enzymes, glutathione reductase and glucose-6-phosphate dehydrogenase in lens, cornea, and retina. Lens contains a high concentration of reduced glutathione, which maintains the thiol groups in the reduced form. These contribute to lens complete transparency as well as to the transparent and refractive properties of the mammalian cornea, which are essential for proper image formation on the retina. In cornea, gluthatione also plays an important role in maintaining normal hydration level, and in protecting cellular membrane integrity. In retina, glutathione is distributed in the different types of retinal cells. Intracellular enzyme, glutathione reductase, involved in reducing the oxidized glutathione has been found at highest activity in human and primate lenses, as compared to other species. Besides the enzymes directly involved in maintaining the normal redox status of the cell, glucose-6-phosphate dehydrogenase which catalyzes the first reaction of the pentose phosphate pathway, plays a key role in protection of the eye against reactive oxygen species. Cornea has a high activity of the pentose phosphate pathway and glucose-6-phosphate dehydrogenase activity. Glycation, the non-enzymic reaction between a free amino group in proteins and a reducing sugar, slowly inactivates gluthathione-related and other enzymes. In addition, glutathione can be also glycated. The presence of glutathione, and of the related enzymes has been also reported in other parts of the eye, such as ciliary body and trabecular meshwork, suggesting that the same enzyme systems are present in all tissues of the eye to generate NADPH and to maintain gluthatione in the reduced form. Changes of glutathione and related enzymes activity in lens, cornea, retina and other eye tissues, occur with ageing, cataract, diabetes, irradiation and administration of some drugs.
203 citations
TL;DR: The concentration of glucose in the tear fluid changes proportionately with respect to capillary blood glucose after a carbohydrate challenge, and in the clinical setting this may not prove to be practical due to technical limitations.
Abstract: This study compares tear glucose dynamic differences between 121 diabetic and nondiabetic subjects after the administration of a carbohydrate load A quantitative chromatographic analysis of tear glucose was used and the values correlated to blood glucose values Diabetic and nondiabetic tear glucose mean values were 035 ± 004 mmol/L and 016 ± 003 mmol/L, respectively Significant differences were observed among the subject groups in both the tear and capillary blood glucose values A correlation between tear glucose and capillary blood glucose was observed The concentration of glucose in the tear fluid changes proportionately with respect to capillary blood glucose after a carbohydrate challenge Although it is possible to determine the diabetic status of a subject using tear glucose values alone, in the clinical setting this may not prove to be practical due to technical limitations
139 citations
TL;DR: Lysozyme accumulation on group IV lenses reached a maximum on the seventh day and then plateaued, whereas on groups I, II, and SH lenses, deposition continued to increase across all time periods, reiterating that kinetics of lysozyme deposition is highly material dependent.
Abstract: We sought to compare the kinetics of in vitro lysozyme deposition on silicone hydrogel (SH), polymethyl methacrylate (PMMA), and FDA groups I, II, and IV contact lenses. Lenses were incubated in 125I-labeled lysozyme for time periods ranging from 1 hr to 28 days, and radioactive counts were determined. SH lenses and PMMA deposited less lysozyme than conventional hydrogel lenses (p < 0.05). Lysozyme accumulation on group IV lenses reached a maximum on the seventh day and then plateaued, whereas on groups I, II, and SH lenses, deposition continued to increase across all time periods, reiterating that kinetics of lysozyme deposition is highly material dependent.
127 citations
TL;DR: The results suggest that Thy1 serves as an early marker of RGC stress, but not a marker ofRGC loss, in models of retinal damage.
Abstract: Purpose: Thy1 is a surface glycoprotein uniquely expressed in retinal ganglion cells (RGCs) in retina. The aim of this study was to investigate the expression change of Thy1 in a model of experimental glaucoma. Methods: The change of protein and mRNA levels of Thy1 in the retina were studied using stereological counts of back-labeled RGCs, Western blot analysis, immunohistochemistry, and laser capture microdissection (LCM) of RGCs with quantitative PCR analysis of mRNA in a model of experimental glaucoma. LCM after optic nerve crush was also performed to evaluate Thy1 mRNA levels after a different injury. Results: After 10 days of elevated IOP, there was a 34% loss of RGC number, Thy1 protein decreased 60% in eyes with elevated intraocular pressure (IOP), and Thy1 mRNA levels decreased 51% in RGCs. Both protein and mRNA level change of Thy1 is to a much greater extent than RGC number loss. Conclusions: The current results confirm that Thy 1 mRNA levels do not reflect the number of RGCs present and extend ...
108 citations
TL;DR: In this paper, polyvinyl alcohol (PVA) hydrogel crosslinked by gamma irradiation was assessed as a possible vitreous substitute, and the gel was well tolerated in these experiments, though it is necessary to investigate the biocompatibility for the longterm.
Abstract: Polyvinylalcohol (PVA) hydrogel cross-linked by gamma irradiation was assessed as a possible vitreous substitute. From a series of experiments, rise of intraocular pressure and inflammatory changes in the vitreous cavity after operation were observed in some cases. Crab-eating macaques were used for this experiment. PVA gels were injected into vitreous cavity after vitrectomy and followed clinically by opthalmoscopy, tonometry, fundus photography, electroretinogram (ERG), chemotaxis, and flare cell meter. Histopathologic examination by light and electron microscopy was performed after 3 months. As a result, there were no significant changes in ophthalmoscopic findings. No abnormal rising of intraocular pressure (IOP) was recognized. ERG did not show meaningful amplitude weakness. From the photon counting of flare cell meter, significant break of blood-aqueous barrier and blood-retinal barrier was not observed. Histopathologic examination revealed that all layers of the retina were intact and no loss of tissue was evident. However, in PVA gel-injected eyes, some vacuolations of the inner retina were found in some specimens. To conclude, PVA gel was well tolerated in these experiments. The gel with a network similar to the vitreous body showed the best biocompatibility, though it is necessary to investigate the biocompatibility for the long-term. PVA gel is a good candidate for a vitreous substitute.
97 citations
TL;DR: The presence of oxidative stress in selenite cataract development and its prevention by resveratrol support the possibility that high natural consumption of resver atrol in food can help prevent human senile cataracts.
Abstract: Purpose: To investigate if resveratrol can prevent sodium selenite-induced experimental cataract model in rats. Methods: Forty-eight Spraque-Dawley rat pups were divided into 3 treatment groups: (1) normal saline–% 5 ethanol injected i.p. on postpatum day 10; (2) Na selenite (30 nmol/g body wt) injected s.c on day 10; (3) Na selenite s.c on day 10 + resveratrol (40 mg/kg) i.p on days 10–13. On day 21, cataract development was graded by slit-lamp examination and photography. Encapsulated lenses and erythrocytes were analyzed for reduced glutathione (GSH) and malondialdehyde (MDA), a marker of lipid peroxidation. Lenses were also analyzed for total nitrite (TN). Results: All control lenses in group 1 were clear. In group 2, all rats developed cataracts (grade 3–grade 6), whereas in group 3, only 9 of 16 rats developed cataracts (grade 2–grade 3). The difference of cataract frequency between groups 2 and 3 was statistically significant (p < 0.05). Group 3 lenses and erythrocytes had higher mean GSH and lower...
95 citations
TL;DR: It is indicated that acute inflammation and detrimental architectural and electrophysiologic changes in the retina began earlier than once thought, suggesting that therapeutic intervention should be given at the earliest possible time to avoid vision loss during Bacillus endophthalmitis.
Abstract: Rapid vision loss and explosive inflammation are devastating consequences of Bacillus endophthalmitis that have not been well defined. We therefore analyzed the evolution of intraocular inflammation and loss of retinal architecture and function during experimental Bacillus endophthalmitis. Mice were intravitreally injected with 100 CFU of B. cereus, and eyes were analyzed for bacterial growth, retinal function, architectural changes and retinal cellular stress, inflammatory cytokines, and infiltrating cells. Retinal electrophysiologic and structural changes began as early as 4 to 6 hr postinfection. Significant declines in retinal function paralleled the loss of retinal architecture. Glial fibrillary acidic protein (GFAP) was detected in retina, indicating potential stress. Polymorphonuclear leukocyte (PMN) infiltration into the vitreous began as early as 4 hr postinfection, coinciding with a significant increase in TNF-alpha in the eye. These results indicated that acute inflammation and detrimental architectural and electrophysiologic changes in the retina began earlier than once thought, suggesting that therapeutic intervention should be given at the earliest possible time to avoid vision loss during Bacillus endophthalmitis.
88 citations
TL;DR: Lens opacities may affect the image quality of OCT scans used to measure RNFL thickness as indicated by preoperative low SNR which results in an apparent increase of the R NFL thickness.
Abstract: Purpose: To evaluate whether the measurement of retinal nerve fiber layer (RNFL) thickness using optical coherence tomography (OCT) changes after cataract surgery. Methods: This prospective, randomized, observational, cross-sectional clinical study included 24 eyes of 24 patients who underwent phacoemusification with implant. All patients had no preexisting retinal or optic nerve pathology or other media opacities that might influence the RNFL thickness. The classification and the grading of cataract were based on the Lens Opacities Classification System III (LOCS III). All eyes were scanned immediately before cataract surgery with OCT using Fast RNFL program. All eyes had circular scans around the optic disk with a diameter of 3.4 mm. The OCT was repeated 4 weeks after surgery when the patients returned for postoperative check using the same programme. Results: The mean preoperative RNFL thickness was 84.9 ± 16.5. The postoperative mean RNFL thickness was 93.0 ± 17.6. The pre-and postoperative values of ...
77 citations
TL;DR: A dual-grading and adjudication process to classify image quality and determine ECD for a subset of donor endothelial images obtained in the Specular Microscopy Ancillary Study, which is part of the Cornea Donor Study is described.
Abstract: Purpose: To describe reliable methods for determining central corneal endothelial cell density (ECD) in a multicenter eye bank study. Methods: The Specular Microscopy Reading Center utilized a dual-grading procedure and adjudication process to classify image quality and determine ECD for a subset of donor endothelial images obtained in the Specular Microscopy Ancillary Study, which is part of the Cornea Donor Study. Two certified readers classified images as analyzable (excellent, good, fair) or unanalyzable and determined the ECD using a variable frame technique. An adjudicator also evaluated the images if quality classifications by the two readers differed by one grade, if any reader found the image unanalyzable, and/or if the ECD determination between the two readers was ≥ 5%. Results: Image quality categorization by the two readers was identical for 441 (64%) of 688 donor images. The ECD differed by < 5% for 442 (69%) of the 645 analyzable images. The ECD determined by the adjudicator was < 5% differe...
75 citations
TL;DR: The contributions of these retinopetal axons to vision may be predicted from the known effects of serotonin and histamine on retinal neurons, which are components of the ascending arousal system, firing most rapidly when the animal is awake and active.
Abstract: Since 1892, anatomical studies have demonstrated that the retinas of mammals, including humans, receive input from the brain via axons emerging from the optic nerve. There are only a small number of these retinopetal axons, but their branches in the inner retina are very extensive. More recently, the neurons in the brain stem that give rise to these axons have been localized, and their neurotransmitters have been identified. One set of retinopetal axons arises from perikarya in the posterior hypothalamus and uses histamine, and the other arises from perikarya in the dorsal raphe and uses serotonin. These serotonergic and histaminergic neurons are not specialized to supply the retina; rather, they are a subset of the neurons that project via collaterals to many other targets in the central nervous system, as well. They are components of the ascending arousal system, firing most rapidly when the animal is awake and active. The contributions of these retinopetal axons to vision may be predicted from the known effects of serotonin and histamine on retinal neurons. There is also evidence suggesting that retinopetal axons play a role in the etiology of retinal diseases.
75 citations
TL;DR: DCT measures an IOP that is significantly higher than GAT IOP in glaucoma and control subjects but not in ocular hypertensives, which may not be true for the GAT, which increases with the CCT.
Abstract: Purpose: To compare the intraocular pressures (IOP) and ocular pulse amplitudes (OPA) in patients with different types of glaucoma, ocular hypertension (OHT), and normal controls (NC) using dynamic contour tonometry (DCT) and the goldmann applanation tonometry (GAT). Methods: 906 eyes of 501 adult patients in the following five groups were included in this cross-sectional study: primary open angle glaucoma (POAG), normal tension glaucoma (NTG), Pseudoexfoliative Glaucoma (PXG), OHT, and NC. The following tests were performed simultaneously during a single visit: IOP using DCT and GAT; OPA using DCT and central corneal thickness (CCT) using ultrasound pachymetry. Mixed effects regression models were used to compare the DCT and GAT IOP measurements in the five groups; the effect of CCT on IOP and the relationship between OPA and IOP within each group. Results: DCT consistently had higher IOP values than GAT in POAG, PXG, NTG, and controls (p < 0.001) but not in OHT (p = 0.84). DCT IOP did not change while G...
TL;DR: Results indicate that induction of UPR is related not only to absolute concentrations but also to a shifting from higher to lower concentrations of glucose.
Abstract: Diabetic retinopathy is one of the major microvascular complications associated with diabetes mellitus, and the selective degeneration of retinal capillary pericytes is considered to be a hallmark of early retinopathy. Because glucose fluctuations commonly occur in diabetes, we hypothesized that these fluctuations will increase the endoplasmic reticulum (ER) stress and induce the unfolded protein response (UPR) in retinal pericytes. To study whether ER stress and the UPR can be induced in retinal pericytes, rat retinal capillary pericytes were cultured in different concentrations of glucose. Hypoglycemia but not hyperglycemia was found to activate UPR-specific enzymes in pericytes. Strong UPR activation leading to apoptosis was also observed when pericytes were cultured in glucose concentrations that were reduced from high to low or no glucose. These results indicate that induction of UPR is related not only to absolute concentrations but also to a shifting from higher to lower concentrations of glucose.
TL;DR: The fibrin adhesive had no adverse effects on ocular tissue compared with sutures and might serve as an effective substitute for conjunctival and scleral wound closure in trabeculectomy surgery.
Abstract: Purpose: To describe the outcome of the use of fibrin adhesive (Quixil) in penetrating trabeculectomy in a rabbit model. Methods: Fibrin adhesive was used experimentally to attach the conjunctiva and the scleral flap in two groups of 17 New Zealand albino adult rabbits (34 eyes). In the first experiment (20 eyes), the fibrin adhesive was used to reattach the tissue after conjunctival peritomy and scleral flap only in 14 eyes (experiment I). In 6 eyes (controls), the conjunctiva was attached with nylon sutures. In the second experiment (14 eyes), the fibrin adhesive was used after conjunctival peritomy, scleral flap, and penetrating trabeculectomy in 8 eyes (experiment II). In a control group of 6 eyes, nylon sutures were used to attach the scleral flap and the conjunctiva after penetrating trabeculectomy. Biomicroscopy and histopathological examinations were performed on postoperative days 1, 3, 7, 14, 21, and 30. Intraocular pressure was measured before and after surgery in the second experiment. Main ou...
TL;DR: In this article, the characteristics of four different types of retinal pigment epithelium (RPE) cells were investigated and compared for 2 to 5 weeks to provide guidance when choosing RPE cells for experimentation.
Abstract: Purpose: To investigate and compare the characteristics of four different types of retinal pigment epithelium (RPE) cells cultured for 2 to 5 weeks to provide guidance when choosing RPE cells for experimentation. Methods: Human cell lines ARPE-19 (ARPE) and D407, primary RPE cells from C57Bl/6 mouse (mRPE), and primary human fetal RPE (hfRPE) cells were grown in respective media previously reported to be optimal for each cell type. Two methods to obtain hfRPE were used: one isolated outside and transported to our laboratory, and one isolated primarily within our laboratory from donor human fetal eyes. Barrier function was determined by transepithelial electrical resistance (TER) and permeability and structure by localization of Na+,K+-ATPase α-1, ZO-1, and actin. VEGF expression, determined by real-time polymerase chain reaction (PCR) for mRNA and ELISA for protein, was determined after exposure to 24 h of 1% oxygen. Madin-Darby canine kidney (MDCK) cells were compared as a non-RPE epithelial cell line. R...
TL;DR: The Rostock Cornea Module of the HRT II can provide high-resolution images of all corneal layers of rabbits, rats, and mice without sacrificing animals or preparing tissue.
Abstract: Purpose: The aim of the current study was to compare the corneas of three commonly used laboratory animals with a new in vivo confocal microscope. Methods: Six eyes of three adult male New Zealand albino rabbits, six eyes of three adult male Lewis rats, and six eyes of three adult male Swiss mice were used in this study. Corneas were analyzed in vivo using the Rostock Cornea Module of the Heidelberg Retina Tomograph (HRT)-II. For all eyes, 20 confocal microscopic images of each layer, that is, the superficial and basal corneal epithelia, the Bowman layer, the anterior and posterior stroma, and the endothelium, were recorded. The images were then analyzed qualitatively and compared among animals. Cellular densities of anterior and posterior stroma keratocytes of rabbits and endothelium density of the three different animals were also measured and compared. Results: The Rostock Cornea Module of the HRT II was successfully used to analyze all corneal layers of these three commonly used laboratory animals. Al...
TL;DR: The results suggest that multidrug resistance may be more commonly associated with the corneal isolates of P. aeruginosa having type III secretion system-associated cytotoxin gene exoU and belonging to serotype E (O:11) group.
Abstract: The association between possession of toxin gene-related type III secretory system, protease profiles, O serotypes, and antibiotic resistance patterns was characterized genetically and phenotypically in 46 keratitis isolates of Pseudomonas aeruginosa. There was no significant difference in exoU or exoS prevalence among the keratitis strains. Distinct protease profiles were seen in isolates harboring either exoU or exoS genes. One hundred percent (13/13) of serotype E (O:11) strains contained type III secretion system–associated cytotoxin gene exoU. Multidrug resistance was identified in 4% of Australian and 29% of Indian isolates. None of the Australian isolates was resistant to ciprofloxacin. In general, the rate of multidrug resistance in the exoU positive cytotoxic and serotype E (O:11) strains was significantly higher than in exoS positive invasive strains (p < 0.01). The results suggest that multidrug resistance may be more commonly associated with the corneal isolates of P. aeruginosa having type II...
TL;DR: Studies with the rat selenite cataract model strongly support the activity of melatonin as an endogenous antioxidant and anticataract agent.
Abstract: Purpose :T oevaluate effects of melatonin on sodium selenite- induced cataract formation Methods :T wenty-three Sprague-Dawley rat pups were randomized into three groups Group 1(n = 9), injected with selenite (sc) on postpartum day 10; group 2 (n = 7), injected with selenite (sc) on day 10 plus melatonin (ip) on days 8-15; group 3 (n = 7), saline-injected controls Development of cataract was assessed weekly under a dissection microscope Rat lenses and serums were analyzed for antioxidant enzymes superoxide dis- mutase (SOD) and catalase (CAT); oxidative stress indicators xanthine oxidase (XO) and malondialdehyde (MDA), a marker of lipid peroxidation; and pro- tein carbonyl (PC), a marker of protein oxidation Results: Significant differences (p < 005) were seen in cataract development by the three groups All rats devel- oped dense nuclear cataract in group 1 Dense nuclear cataract was not observed in group 2: five of seven rats developed minor cataracts, while the other two had clear lenses In control rats (group 3), all lenses remained clear In selenite group (group 1), lens and serum levels of MDA, PC, and XO were significantly higher and levels of SOD and CAT were significantly lower than those in con- trol group (p < 0001) In selenite+melatonin group (group 2), lens and serum levels of MDA, PC, and XO significantly decreased and levels of SOD and CAT significantly increased when compared with selenite group Conclusions: Studies with the rat selenite cataract model strongly support the activity of melatonin as an endogenous antioxidant and anticataract agent
TL;DR: Levels of mRNAs for several key members of the EGF and TGF-β systems increase during corneal wound healing, which suggest these cells are active in synthesizing autocrine and paracrine growth factors that modulate cornean wound healing.
Abstract: Purpose: Members of the epidermal growth factor (EGF) and transforming growth factor beta (TGF-β) families of growth factors and receptors are known to regulate key aspects of corneal wound healing, including epithelial migration and scar formation. To further understand their roles, mRNA levels were measured and proteins were immunolocalized in rat corneas at multiple time points during healing of excimer laser ablation injury. Methods: Excimer laser photoablation was performed to a depth of 50 μm on rat corneas. Levels of mRNAs for EGF, TGF-α, TGF-β isoforms 1, 2, and 3, and their receptors (EGF-R and TGFβ-IIR) were measured by quantitative RT-PCR on days 0, 1.5, 7, 21, 42, and 91 after ablation. Immunohistochemical localization of the growth factors and their receptors was performed on days 0, 7, and 21 in corneal sections. Results: Levels of EGF mRNA remained stable in rat corneas after ablation (68 ± 12 copies/cell, mean ± SD), whereas levels of TGF-α mRNA progressively increased sixfold to a maximum...
TL;DR: Findings represent the first report of B. thuringiensis as an important ocular pathogen, demonstrates the potential ocular toxicity of Bacillus, and identifies antibiotics whose efficacy against Bacillus were superior to those used clinically.
Abstract: Bacillus causes one of the most rapidly blinding intraocular infections: endophthalmitis In this study, Bacillus spp were isolated from ocular infection cases, taxonomically characterized by riboprint analysis, and screened for the presence of putative virulence factors The ability of these isolates to kill retinal and corneal cells was examined, as were antibiotic susceptibility profiles The majority of isolates belonged to the B cereus taxonomic group of microorganisms and were identified as B cereus (53%) or B thuringiensis (26%) Toxins were identified in most B thuringiensis and B cereus isolates Most B cereus and B thuringiensis killed corneal and retinal cells within 6 h All isolates were susceptible to most antibiotics tested, with quinolones and vancomycin being the most potent These findings represent the first report of B thuringiensis as an important ocular pathogen, demonstrates the potential ocular toxicity of B cereus and B thuringiensis isolates, and identifies antibiotics whose efficacy against Bacillus were superior to those used clinically
TL;DR: This study demonstrated the presence of mAChR subtypes (m1 to m5) in human scleral fibroblasts at both mRNA and protein levels, indicating that the sclera is a potential site of action for the currently used mA ChR antagonists in prevention of human myopia.
Abstract: Purpose: The aim of this study was to identify the presence of muscarinic acetylcholine receptors (mAChRs) in human sclera in order to determine whether the sclera is a potential site of action for mAChR antagonists. Methods: Cell lines of human scleral fibroblasts were cultured in Dulbecco modified Ealge's medium. Reverse transcription–polymerase chain reaction (RT-PCR) and Northern blot analysis were used to detect mRNA expression of muscarinic acetylcholine receptors in the cell lines of the fibroblasts. Western blot analysis and immunocytochemistry were used to detect proteins of mAChRs in the cell lines. Immunohistochemical study was used to further detect the presence of mAChR proteins in the frozen scleral sections. Results: The cultured fibroblasts demonstrated mRNA expression of five mAChRs (m1 to m5) in RT-PCR and Northern blot analysis. The molecular size of mRNA expression was largest for the m3 receptor, followed by the m2, m4, m5, and m1 in both RT-PCR and Northern blot analysis. Proteins of...
TL;DR: In the three-month STZ-induced diabetic rat, retinal ganglion cell loss is associated with morphology change, and the surviving RGCs in the diabetic retina, especially those in RGA group, show significant dendritic field enlargement.
Abstract: Purpose: To determine the effect of three-month diabetes on the retinal ganglion cell (RGC) morphology and density. Methods: Experimental diabetes was induced in Sprague-Dawley rats by intraperitoneal injection of streptozotocin (STZ). Retinas from three-month diabetic and age-matched control rats were harvested, and immunohistochemistry with monoclonal anti-Thy-1 antibody was carried out for calculating RGC density. Random RGC labeling with gene gun propelled lipophilic fluorescent dye, DiI, coated particles (DiOlistic method) was done for detailed RGC classification, dendritic field, and soma size measurement. Results: The number of Thy1-labeled RGCs in the three-month diabetic rats was significantly reduced compared with that in the age-matched control. Obvious RGC morphology changes were observed, and the number of RGCs that could not be classified was significantly greater in the diabetic retinas. Among those well-classified RGCs, cells with enlarged dendritic fields were more frequently seen in the ...
TL;DR: The results showed that the intravitreous drug concentration remained within the therapeutic range along the 8-week period of evaluation, and the system under study was not toxic to the normal rabbit retina, and no significant increase in intraocular pressure was observed.
Abstract: The treatment of vitreoretinal diseases is limited and, nowadays, new drug delivery approaches have been reported in order to increase drug bioavailability. The objective of the current study was to determine the pharmacokinetic profile of a biodegradable dexamethasone acetate implant inserted into the vitreous of rabbits and to evaluate its potential signs of toxicity to the rabbits' eyes. The results showed that the intravitreous drug concentration remained within the therapeutic range along the 8-week period of evaluation. The system under study was not toxic to the normal rabbit retina, and no significant increase in intraocular pressure was observed.
TL;DR: An optical method combining pO2 phosphorescence imaging with chorioretinal optical sectioning was established that can potentially be applied for better understanding of retinal and choroidal oxygen dynamics in physiologic and pathologic states.
Abstract: Purpose: To report an optical imaging system that was developed to measure oxygen tension (pO2) in the chorioretinal vasculatures. The feasibility of the system for the measurement of changes in pO2 separately in the retinal and choroidal vasculatures was established in rat eyes by varying the fraction of inspired oxygen and inhibiting nitric oxide activity. Methods: Our optical section phosphorescence imaging system was modified to provide quantitative measurements of pO2 separately in the retinal and choroidal vasculatures. A narrow laser line was projected at an angle on the retina after intravenous injection of an oxygen-sensitive probe (Pd-porphyrin), and phosphorescence emission was imaged. A frequency-domain approach allowed measurements of the phosphorescence lifetime by varying the phase relationship between the modulated excitation laser light and sensitivity of the imaging camera. Chorioretinal pO2 was measured while varying the fraction of inspired oxygen and during intravenous infusion of Nω-...
TL;DR: In suture-induced corneal angiogenesis models, diced siRNAs minimized the severity ofAngiogenesis and the approach using diced siRNA can be a new tool for various neovascular ocular diseases.
Abstract: The effects of diced small interfering RNAs (siRNAs) designed for vascular endothelial growth factor (VEGF) on the expression of VEGF in human retinal pigment epithelial cell line ARPE-19 cells in vitro and on corneal angiogenesis in vivo were examined. The exposure to diced siRNAs significantly reduced the VEGF mRNA expression in ARPE-19 cells with minimal toxicity. In suture-induced corneal angiogenesis models, diced siRNAs minimized the severity of angiogenesis. Histological analysis displayed no particular tissue damage in the conjunctiva where siRNA was injected. The approach using diced siRNAs can be a new tool for various neovascular ocular diseases.
TL;DR: The current prospects for the application of various adult ocular stem cells to human therapies for restoration of vision are discussed.
Abstract: Recent advances in stem cell biology have led to the exploration of stem cell-based therapies to treat a wide range of human diseases. In the ophthalmic field, much hope has been placed on the potential use of these cells to restore sight, particularly in those conditions in which other established treatments have failed and in which visual function has been irreversibly damaged by disease or injury. At present, there are many limitations for the immediate use of embryonic stem cells to treat ocular disease, and as more evidence emerges that adult stem cells are present in the adult human eye, it is clear that these cells may have advantages to develop into feasible therapeutic treatments without the problems associated with embryonic research and immune rejection. Here we discuss the current prospects for the application of various adult ocular stem cells to human therapies for restoration of vision.
TL;DR: Vitreous proteins that were differentially expressed in patients suffering from proliferative diabetic retinopathy with active neovascularization were identified and eight candidate proteins believed to be involved in the pathogenesis of proliferative Diabetes Retinopathy were identified.
Abstract: Purpose: To identify vitreous proteins that were differentially expressed in patients suffering from proliferative diabetic retinopathy with active neovascularization. Methods: The vitreous samples of 15 active proliferative diabetic retinopathy patients were analyzed by two-dimensional gel electrophoresis and mass spectrometry, and the results were compared with those from age-matched patients with macular hole. Results: Twenty-five protein spots were identified in the two-dimensional gel electrophoresis gels. Eight proteins (pigmented epithelium derived factor, serine protease inhibitor, apolipoprotein A-IV precursor, prostaglandin-H2 D-isomerase, α1-antitrypsin precursor, ankyrin repeat domain 15 protein, alpha2-HS-glycoprotein, and beta V spectrin) in the 25 spots were expressed significantly differently between the macular hole and proliferative diabetic retinopathy patients (p value < 0.05). Five proteins were upregulated in the proliferative diabetic retinopathy patients, and three were downregulat...
TL;DR: Investigating the oxidant/antioxidant status and protein oxidation in pseudoexfoliation syndrome suggested a possible role of oxidative stress in pathology of PEX syndrome and decreased SOD activity and higher levels of MDA and PC indicate increased oxidative stress.
Abstract: Purpose: To investigate the oxidant/antioxidant status and protein oxidation in pseudoexfoliation syndrome. Methods: The activity of serum superoxide dismutase (SOD) and the levels of serum malondialdehyde (MDA) and protein carbonyl (PC) were measured in 50 patients with pseudoexfoliation (PEX) and in 55 healthy controls. Results: There was significant difference in the SOD activity in PEX group compared with the control group (p < 0.001). In addition, MDA and PC levels were significantly higher in patients than in the controls (p < 0.001). Conclusions: Decrease in SOD activity and the higher levels of MDA and PC indicate increased oxidative stress. Our results suggest a possible role of oxidative stress in pathology of PEX syndrome.
TL;DR: In this article, a study was undertaken to assess serial month-to-month consistency of macular pigment optical density and serum concentrations of lutein (L) and zeaxanthin (Z).
Abstract: Purpose: This study was undertaken to assess serial month-to-month consistency of macular pigment (MP) optical density and serum concentrations of lutein (L) and zeaxanthin (Z). Four healthy subjects aged between 23 and 51 years volunteered to participate in this study. Methods: MP optical density (measured psychophysically using heterochromatic flicker photometry [HFP]), and serum concentrations of L and Z (quantified using high-performance liquid chromatography [HPLC]), were recorded every month for 24 consecutive months. Results: Mean MP optical density (±SD) was 0.361 (0.086) and 0.369 (0.074) for right and left eyes, respectively. There was no statistically significant seasonal variation in MP optical density for the group (two-way ANOVA: p > 0.05). Serum concentrations of L and Z demonstrated a statistically significant subject-season interaction effect (two-way ANOVA: p < 0.01). Serial serum concentrations of L and Z were positively correlated within all four subjects (r = 0.370 to 0.786), and sign...
TL;DR: Results obtained from both in vitro and ex vivo studies suggest the possible role of SMVT expressed on corneal epithelial cells for the uptake of biotin, which co-transports pantothenic acid and lipoic acid.
Abstract: Purpose: The objective of this research was to investigate the presence of sodium-dependent multivitamin transporter (SMVT) on rabbit corneal epithelial cells. Methods: Primary cultured rabbit corneal epithelial cells (rPCECs)and freshly excised rabbit corneas were used for characterization of biotin uptake and transport, respectively. Reverse transcription–polymerase chain reaction (RT-PCR) was performed to confirm the molecular identity of SMVT. Liquid chromatography/tandem mass spectrometry (LC-MS/MS) analysis was performed to examine the presence of biotin in rabbit tears. Results: Uptake of biotin by rPCECs was found to be time and concentration dependent with Km of 32.52 μ M and Vmax of 10.43 pmol min− 1 mg protein− 1. Biotin was significantly inhibited in the presence of pantothenic acid and lipoic acid. Biotin uptake was found to be energy and Na+ dependent but H+ and Cl− independent. The uptake was inhibited by valeric acid in a concentration-dependent manner but not much affected in the presence...
TL;DR: A saturable, sodium dependent, and pH sensitive transporter with high specificity for L-ascorbic acid was functionally characterized and was identified as SVCT2.
Abstract: Purpose: To investigate the mechanism of L-ascorbic acid uptake by rabbit corneal epithelial cells and to functionally characterize the specific transporter involved in this translocation process. Methods: Uptake studies were carried out with SIRC (Statens Seruminstitut Rabbit Cornea) and rPCEC (rabbit Primary corneal epithelial cell culture) in 12-well plates using [14C] Ascorbic acid (AA). Uptake was done in the presence of L-ascorbic acid and D-isoascorbic acid to delineate stereospecificity. Inhibition studies were performed in the presence of D-glucose a substrate for GLUT and also para amino hippuric acid (PAHA) a substrate for organic anion transporter. Effects of pH and sodium on the uptake of AA were characterized. Concentration dependency studies were performed. Energy dependence of AA uptake was investigated with ouabain and sodium azide in rPCEC. Reverse Transcription-polymerase chain reaction (RT-PCR) was also performed. Results: Uptake of AA was inhibited by about 90% and 50% respectively in...