Kohanim S, Daniels AB, Huynh N, Eliott D, Chodosh J. Utility of ocular ultrasonography in diagnosing infectious endophthalmitis in patients with media opacities. Semin Ophthalmol 2012;27(5-6):242-5.Abstract
Assessment of patients with infectious endophthalmitis is frequently limited by media opacities, and ocular ultrasonography is routinely performed in this setting. We examined the literature to assess the level of evidence for the utility of ocular ultrasonography in these patients. Common ultrasonographic findings reported include low amplitude mobile echoes, vitreous membranes, and thickening of the retina and choroid. Based on the available evidence, we conclude that ocular ultrasound may be a useful adjunct in guiding treatment and minimizing complications. While positive findings may be confirmatory in cases in which the clinical suspicion is high, ocular ultrasound alone cannot be used to prove or to exclude the diagnosis of infectious endophthalmitis.
Rajaiya J, Yousuf MA, Singh G, Stanish H, Chodosh J. Heat shock protein 27 mediated signaling in viral infection. Biochemistry 2012;51(28):5695-702.Abstract
Heat shock proteins (HSPs) play a critical role in many intracellular processes, including apoptosis and delivery of other proteins to intracellular compartments. Small HSPs have been shown previously to participate in many cellular functions, including IL-8 induction. Human adenovirus infection activates intracellular signaling, involving particularly the c-Src and mitogen-activated protein kinases [Natarajan, K., et al. (2003) J. Immunol. 170, 6234-6243]. HSP27 and MK2 are also phosphorylated, and c-Src, and its downstream targets, p38, ERK1/2, and c-Jun-terminal kinase (JNK), differentially mediate IL-8 and MCP-1 expression. Specifically, activation and translocation of transcription factor NFκB-p65 occurs in a p38-dependent fashion [Rajaiya, J., et al. (2009) Mol. Vision 15, 2879-2889]. Herein, we report a novel role for HSP27 in an association of p38 with NFκB-p65. Immunoprecipitation assays of virus-infected but not mock-infected cells revealed a signaling complex including p38 and NFκB-p65. Transfection with HSP27 short interfering RNA (siRNA) but not scrambled RNA disrupted this association and reduced the level of IL-8 expression. Transfection with HSP27 siRNA also reduced the level of nuclear localization of NFκB-p65 and p38. By use of tagged p38 mutants, we found that amino acids 279-347 of p38 are necessary for the association of p38 with NFκB-p65. These studies strongly suggest that HSP27, p38, and NFκB-p65 form a signalosome in virus-infected cells and influence downstream expression of pro-inflammatory mediators.
Pennock S, Kazlauskas A. Vascular endothelial growth factor A competitively inhibits platelet-derived growth factor (PDGF)-dependent activation of PDGF receptor and subsequent signaling events and cellular responses. Mol Cell Biol 2012;32(10):1955-66.Abstract
Certain platelet-derived growth factor (PDGF) isoforms are associated with proliferative vitreoretinopathy (PVR), a sight-threatening complication that develops in a subset of patients recovering from retinal reattachment surgery. Although these PDGF isoforms are abundant in the vitreous of patients and experimental animals with PVR, they make only a minor contribution to activating PDGF receptor α (PDGFRα) and driving experimental PVR. Rather, growth factors outside of the PDGF family are the primary (and indirect) agonists of PDGFRα. These observations beg the question of why vitreal PDGFs fail to activate PDGFRα. We report here that vitreous contains an inhibitor of PDGF-dependent activation of PDGFRα and that a major portion of this inhibitory activity is due to vascular endothelial cell growth factor A (VEGF-A). Furthermore, recombinant VEGF-A competitively blocks PDGF-dependent binding and activation of PDGFR, signaling events, and cellular responses. These findings unveil a previously unappreciated relationship between distant members of the PDGF/VEGF family that may contribute to pathogenesis of a blinding eye disease.
Murakami Y, Matsumoto H, Roh M, Suzuki J, Hisatomi T, Ikeda Y, Miller JW, Vavvas DG. Receptor interacting protein kinase mediates necrotic cone but not rod cell death in a mouse model of inherited degeneration. Proc Natl Acad Sci U S A 2012;109(36):14598-603.Abstract
Retinitis pigmentosa comprises a group of inherited retinal photoreceptor degenerations that lead to progressive loss of vision. Although in most cases rods, but not cones, harbor the deleterious gene mutations, cones do die in this disease, usually after the main phase of rod cell loss. Rod photoreceptor death is characterized by apoptotic features. In contrast, the mechanisms and features of subsequent nonautonomous cone cell death remain largely unknown. In this study, we show that receptor-interacting protein (RIP) kinase mediates necrotic cone cell death in rd10 mice, a mouse model of retinitis pigmentosa caused by a mutation in a rod-specific gene. The expression of RIP3, a key regulator of programmed necrosis, was elevated in rd10 mouse retinas in the phase of cone but not rod degeneration. Although rd10 mice lacking Rip3 developed comparable rod degeneration to control rd10 mice, they displayed a significant preservation of cone cells. Ultrastructural analysis of rd10 mouse retinas revealed that a substantial fraction of dying cones exhibited necrotic morphology, which was rescued by Rip3 deficiency. Additionally, pharmacologic treatment with a RIP kinase inhibitor attenuated histological and functional deficits of cones in rd10 mice. Thus, necrotic mechanisms involving RIP kinase are crucial in cone cell death in inherited retinal degeneration, suggesting the RIP kinase pathway as a potential target to protect cone-mediated central and peripheral vision loss in patients with retinitis pigementosa.
Makino CL, Wen X-H, Michaud NA, Covington HI, DiBenedetto E, Hamm HE, Lem J, Caruso G. Rhodopsin expression level affects rod outer segment morphology and photoresponse kinetics. PLoS One 2012;7(5):e37832.Abstract
BACKGROUND: The retinal rod outer segment is a sensory cilium that is specialized for the conversion of light into an electrical signal. Within the cilium, up to several thousand membranous disks contain as many as a billion copies of rhodopsin for efficient photon capture. Disks are continually turned over, requiring the daily synthesis of a prodigious amount of rhodopsin. To promote axial diffusion in the aqueous cytoplasm, the disks have one or more incisures. Across vertebrates, the range of disk diameters spans an order of magnitude, and the number and length of the incisures vary considerably, but the mechanisms controlling disk architecture are not well understood. The finding that transgenic mice overexpressing rhodopsin have enlarged disks lacking an incisure prompted us to test whether lowered rhodopsin levels constrain disk assembly. METHODOLOGY/PRINCIPAL FINDINGS: The structure and function of rods from hemizygous rhodopsin knockout (R+/-) mice with decreased rhodopsin expression were analyzed by transmission electron microscopy and single cell recording. R+/- rods were structurally altered in three ways: disk shape changed from circular to elliptical, disk surface area decreased, and the single incisure lengthened to divide the disk into two sections. Photocurrent responses to flashes recovered more rapidly than normal. A spatially resolved model of phototransduction indicated that changes in the packing densities of rhodopsin and other transduction proteins were responsible. The decrease in aqueous outer segment volume and the lengthened incisure had only minor effects on photon response amplitude and kinetics. CONCLUSIONS/SIGNIFICANCE: Rhodopsin availability limits disk assembly and outer segment girth in normal rods. The incisure may buffer the supply of structural proteins needed to form larger disks. Decreased rhodopsin level accelerated photoresponse kinetics by increasing the rates of molecular collisions on the membrane. Faster responses, together with fewer rhodopsins, combine to lower overall sensitivity of R+/- rods to light.
Lucas K, Karamichos D, Mathew R, Zieske JD, Stein-Streilein J. Retinal laser burn-induced neuropathy leads to substance P-dependent loss of ocular immune privilege. J Immunol 2012;189(3):1237-42.Abstract
Inflammation in the eye is tightly regulated by multiple mechanisms that together contribute to ocular immune privilege. Many studies have shown that it is very difficult to abrogate the immune privileged mechanism called anterior chamber-associated immune deviation (ACAID). Previously, we showed that retinal laser burn (RLB) to one eye abrogated immune privilege (ACAID) bilaterally for an extended period of time. In an effort to explain the inflammation in the nonburned eye, we postulated that neuronal signals initiated inflammation in the contralateral eye. In this study, we test the role of substance P, a neuroinflamatory peptide, in RLB-induced loss of ACAID. Histological examination of the retina with and without RLB revealed an increase of the substance P-inducible neurokinin 1 receptor (NK1-R) in the retina of first, the burned eye, and then the contralateral eye. Specific antagonists for NK1-R, given locally with Ag within 24 h, but not 3, 5, or 7 d post-RLB treatment, prevented the bilateral loss of ACAID. Substance P knockout (KO) mice retained their ability to develop ACAID post-RLB. These data support the postulate that substance P transmits early inflammatory signals from the RLB eye to the contralateral eye to induce changes to ocular immune privilege and has a central role in the bilateral loss of ACAID. The possibility is raised that blocking of the substance P pathway with NK1-R antagonists postocular trauma may prevent unwanted and perhaps extended consequences of trauma-induced inflammation in the eye.
Lefebvre DR, Freitag SK. Update on imaging of the lacrimal drainage system. Semin Ophthalmol 2012;27(5-6):175-86.Abstract
Epiphora is a common problem seen by the ophthalmologist. There are numerous etiologies of a watering eye, and the underlying diagnosis is not always clear. A variety of in-office examination techniques and procedures exist to aid with diagnosis and determination of appropriate therapy, but sometimes the diagnosis remains elusive, or an instituted therapy fails. Lacrimal imaging, particularly in these cases, can be helpful in assessing the function and anatomy of the lacrimal drainage system. This review serves to examine the literature of the last 10 years concerning imaging of the lacrimal drainage system.
Sahin A, Hamrah P. Clinically relevant biometry. Curr Opin Ophthalmol 2012;23(1):47-53.Abstract
PURPOSE OF REVIEW: Obtaining precise postoperative target refraction is of utmost importance in today's modern cataract and refractive surgery. Given the growing number of patients undergoing premium intraocular lens (IOL) implantations, patient expectation continues to rise. In order to meet heightened patient expectations, it is crucial to pay utmost attention to patient selection, accurate keratometry and biometry readings, as well as to the application of correct IOL power formula with optimized lens constants. This article reviews recent advances in the field of clinical biometry and IOL power calculations. RECENT FINDINGS: Recently developed low-coherence reflectometry optical biometry is comparable to older ultrasonic biometric and keratometric techniques. In addition, the new IOLMaster software upgrade has improved reproducibility and enhanced signal acquisition. Further, the modern lens power formulas currently determine the effective lens position and the shape of the intraocular lens power prediction curve more accurately. SUMMARY: In order to reach target refraction, precise biometric measurements are imperative. Understanding the strengths and limitations of the currently available biometry devices allows prevention of high variability and inaccuracy, ultimately determining the refractive outcomes.
Kovacs K, Wagley S, Quirk MT, Ceron OM, Silva PA, Singh RJ, Gukasyan HJ, Arroyo JG. Pharmacokinetic study of vitreous and serum concentrations of triamcinolone acetonide after posterior sub-tenon's injection. Am J Ophthalmol 2012;153(5):939-48.Abstract
PURPOSE: To compare a theoretical pharmacokinetic model of triamcinolone acetonide after posterior sub-Tenon's injection with experimental serum and undiluted vitreous triamcinolone acetonide concentrations obtained during pars plana vitrectomy. DESIGN: Clinical-practice, prospective, interventional case series study. METHODS: This study compared computer-modeled triamcinolone acetonide diffusion after posterior sub-Tenon's injection with triamcinolone acetonide levels in experimental undiluted vitreous and serum samples from 57 patients undergoing vitrectomy assessed via mass spectrometry and high-pressure liquid chromatography. At least 5 pairs of samples were collected at each of 7 time points (1 day, 3 days, and 1, 2, 3, 4, and 8 weeks) after triamcinolone acetonide injection, with 6 controls without injection. Cortisol levels were measured in 31 sets of samples. RESULTS: The theoretical model predicted that triamcinolone acetonide levels in systemic blood, vitreous, and choroidal extracellular matrix would plateau after 3 days at 15 ng/mL, 227 ng/mL and 2230 ng/mL, respectively. Experimental vitreous levels of triamcinolone peaked at 111 ng/mL at day 1, then reached a plateau in the range 15 to 25 ng/mL, while serum triamcinolone levels peaked at day 3 near 35 ng/mL and plateaued near 2 to 8 ng/mL. Serum triamcinolone and cortisol levels were inversely correlated (Spearman -0.42, P = .02). CONCLUSIONS: The theoretical model predicts efficient delivery of triamcinolone acetonide from the posterior sub-Tenon's space to the extracellular choroidal matrix. The experimental findings demonstrate low levels of serum triamcinolone that alter systemic cortisol levels and higher vitreous levels lasting at least 1 month. Both assessments support trans-scleral delivery of posterior sub-Tenon's triamcinolone.
Robb RM, Elliott AT, Robson CD. Developmental conjunctival cyst of the eyelid in a child. J AAPOS 2012;16(2):196-8.Abstract
Conjunctival cysts unrelated to surgery or trauma are uncommon adnexal lesions in children and may be difficult to recognize. We report the clinical and pathological findings of an apparently spontaneous conjunctival cyst in the upper eyelid of a child whose first ophthalmological examination was at 7 months of age. The cyst was surgically excised at 5 years of age.
Perry LJP, Jakobiec FA, Zakka FR, Rubin PAD. Giant dacryocystomucopyocele in an adult: a review of lacrimal sac enlargements with clinical and histopathologic differential diagnoses. Surv Ophthalmol 2012;57(5):474-85.Abstract
Dacryocystocele is an umbrella term that refers to any diffuse, centrifugal enlargement of the lacrimal sac that results from combined proximal and distal obstructions in the tear drainage system. In adults, the presence of mucus in the cyst's contents leads to the modified term of dacryocystomucocele. If infection supervenes, which almost always occurs in protracted cases and adds the clinical dimension of a dacryocystitis, then a dacryocystomucopyocele is created. Dacryocystocele and its congeners are much rarer in adults than in children. We describe a 95-year-old woman with an acquired, enormous dacryocystomucopyocele, larger than any previously reported, that developed over 25 years and produced globe displacement with an associated conspicuous enlargement of the nasolacrimal duct. The aspirated sac fluid was mucopurulent and harbored low-virulence bacterial organisms of the Prevotella and Petosteptococcus species. In infants, dacryocystoceles are transitory as the result of spontaneously reversible factors. In adults, secondary proximal irreversible fibrotic strictures or bony changes around the nasolacrimal duct typically arise from chronic inflammation or low grade infection. Other possible causations of duct obstruction, in addition to florid mucosal edema, include encroachment on the duct by enlarged contiguous ethmoid air cells; a sinus mucocele or sinusitis; idiopathic, post-traumatic or dysplastic bony remodeling of the wall of the duct; and a neoplasm-all of which require some form of surgical intervention, typically dacryocystorhinostomy. The differential diagnosis of medial canthal swellings centered on the lacrimal sac spans malformations, diverticula, dermoid/epidermoid cysts, sac inflammations/infections causing swelling without generalized sac enlargement, encephaloceles and primary epithelial tumors, as well as extrinsic tumors impinging on the sac.
Palmer KL, Godfrey P, Griggs A, Kos VN, Zucker J, Desjardins C, Cerqueira G, Gevers D, Walker S, Wortman J, Feldgarden M, Haas B, Birren B, Gilmore MS. Comparative genomics of enterococci: variation in Enterococcus faecalis, clade structure in E. faecium, and defining characteristics of E. gallinarum and E. casseliflavus. MBio 2012;3(1):e00318-11.Abstract
The enterococci are Gram-positive lactic acid bacteria that inhabit the gastrointestinal tracts of diverse hosts. However, Enterococcus faecium and E. faecalis have emerged as leading causes of multidrug-resistant hospital-acquired infections. The mechanism by which a well-adapted commensal evolved into a hospital pathogen is poorly understood. In this study, we examined high-quality draft genome data for evidence of key events in the evolution of the leading causes of enterococcal infections, including E. faecalis, E. faecium, E. casseliflavus, and E. gallinarum. We characterized two clades within what is currently classified as E. faecium and identified traits characteristic of each, including variation in operons for cell wall carbohydrate and putative capsule biosynthesis. We examined the extent of recombination between the two E. faecium clades and identified two strains with mosaic genomes. We determined the underlying genetics for the defining characteristics of the motile enterococci E. casseliflavus and E. gallinarum. Further, we identified species-specific traits that could be used to advance the detection of medically relevant enterococci and their identification to the species level.
Merabet LB, Connors EC, Halko MA, Sánchez J. Teaching the blind to find their way by playing video games. PLoS One 2012;7(9):e44958.Abstract
Computer based video games are receiving great interest as a means to learn and acquire new skills. As a novel approach to teaching navigation skills in the blind, we have developed Audio-based Environment Simulator (AbES); a virtual reality environment set within the context of a video game metaphor. Despite the fact that participants were naïve to the overall purpose of the software, we found that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building using audio based cues alone. This was confirmed by a series of behavioral performance tests designed to assess the transfer of acquired spatial information to a large-scale, real-world indoor navigation task. Furthermore, learning the spatial layout through a goal directed gaming strategy allowed for the mental manipulation of spatial information as evidenced by enhanced navigation performance when compared to an explicit route learning strategy. We conclude that the immersive and highly interactive nature of the software greatly engages the blind user to actively explore the virtual environment. This in turn generates an accurate sense of a large-scale three-dimensional space and facilitates the learning and transfer of navigation skills to the physical world.
Maker MP, Noble J, Silva PS, Cavallerano JD, Murtha TJ, Sun JK, Aiello LM, Bursell S-E, Aiello LP. Automated Retinal Imaging System (ARIS) compared with ETDRS protocol color stereoscopic retinal photography to assess level of diabetic retinopathy. Diabetes Technol Ther 2012;14(6):515-22.Abstract
BACKGROUND: Early Treatment Diabetic Retinopathy Study (ETDRS) seven-standard-field color stereoscopic retinal photography (ETDRS photos) has been a gold standard for determining diabetic retinopathy (DR) severity. The Automated Retinal Imaging System (ARIS™, model 110, Visual Pathways, Inc., Prescott, AZ) acquires seven-sequential color stereoscopic digital images (ARIS images) by a semiautomated technician-run process generally corresponding to ETDRS photos. We assessed the correlation between a single semiautomated ARIS imaging session without any re-imaging and ETDRS photos performed by a certified photographer for the determination of DR severity. METHODS: Two independent masked readers graded mydriatic ARIS images and ETDRS photos. A third masked retinal specialist adjudicated discrepancies. Correlation between the two modalities was compared using weighted-κ statistics. RESULTS: We evaluated 211 eyes of 106 patients with varying levels of DR. Partially ungradable images were present in 3.4% of ETDRS photos versus 31.8% of ARIS images. Exact agreement and agreement within one level between ETDRS photos and ARIS images using only completely gradable image sets occurred in 69% (κ=0.81) and 90% of cases, respectively. Exact agreement for clinically significant macular edema was 92.1% (κ=0.59). There was 100% agreement for eyes with high-risk proliferative DR. Within one level of DR severity, 100% agreement occurred for the following: questionable nonproliferative DR (NPDR), moderate NPDR, and severe NPDR. CONCLUSIONS: Results suggest that semiautomated ARIS images compare favorably with ETDRS photos when full image sets can be obtained; however, partially ungradable image sets occurred almost 10 times more frequently with ARIS images than with ETDRS photos. In the two-thirds of cases where ARIS images can be utilized, ARIS can obtain retinal images comparable to ETDRS photos while requiring less highly trained personnel than generally needed for standard ETDRS photos.
Liu Q, Collin RWJ, Cremers FPM, den Hollander AI, van den Born IL, Pierce EA. Expression of wild-type Rp1 protein in Rp1 knock-in mice rescues the retinal degeneration phenotype. PLoS One 2012;7(8):e43251.Abstract
Mutations in the retinitis pigmentosa 1 (RP1) gene are a common cause of autosomal dominant retinitis pigmentosa (adRP), and have also been found to cause autosomal recessive RP (arRP) in a few families. The 33 dominant mutations and 6 recessive RP1 mutations identified to date are all nonsense or frameshift mutations, and almost exclusively (38 out of 39) are located in the 4(th) and final exon of RP1. To better understand the underlying disease mechanisms of and help develop therapeutic strategies for RP1 disease, we performed a series of human genetic and animal studies using gene targeted and transgenic mice. Here we report that a frameshift mutation in the 3(rd) exon of RP1 (c.686delC; p.P229QfsX35) found in a patient with recessive RP1 disease causes RP in the homozygous state, whereas the heterozygous carriers are unaffected, confirming that haploinsufficiency is not the causative mechanism for RP1 disease. We then generated Rp1 knock-in mice with a nonsense Q662X mutation in exon 4, as well as Rp1 transgenic mice carrying a wild-type BAC Rp1 transgene. The Rp1-Q662X allele produces a truncated Rp1 protein, and homozygous Rp1-Q662X mice experience a progressive photoreceptor degeneration characterized disorganization of photoreceptor outer segments. This phenotype could be prevented by expression of a normal amount of Rp1 protein from the BAC transgene without removal of the mutant Rp1-Q662X protein. Over-expression of Rp1 protein in additional BAC Rp1 transgenic lines resulted in retinal degeneration. These findings suggest that the truncated Rp1-Q662X protein does not exert a toxic gain-of-function effect. These results also imply that in principle gene augmentation therapy could be beneficial for both recessive and dominant RP1 patients, but the levels of RP1 protein delivered for therapy will have to be carefully controlled.