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Sample records for independently firing retinal

  1. Abrupt climate-independent fire regime changes

    USGS Publications Warehouse

    Pausas, Juli G.; Keeley, Jon E.

    2014-01-01

    Wildfires have played a determining role in distribution, composition and structure of many ecosystems worldwide and climatic changes are widely considered to be a major driver of future fire regime changes. However, forecasting future climatic change induced impacts on fire regimes will require a clearer understanding of other drivers of abrupt fire regime changes. Here, we focus on evidence from different environmental and temporal settings of fire regimes changes that are not directly attributed to climatic changes. We review key cases of these abrupt fire regime changes at different spatial and temporal scales, including those directly driven (i) by fauna, (ii) by invasive plant species, and (iii) by socio-economic and policy changes. All these drivers might generate non-linear effects of landscape changes in fuel structure; that is, they generate fuel changes that can cross thresholds of landscape continuity, and thus drastically change fire activity. Although climatic changes might contribute to some of these changes, there are also many instances that are not primarily linked to climatic shifts. Understanding the mechanism driving fire regime changes should contribute to our ability to better assess future fire regimes.

  2. Uniformity detector retinal ganglion cells fire complex spikes and receive only light-evoked inhibition

    PubMed Central

    Sivyer, Benjamin; Taylor, W. Rowland; Vaney, David I.

    2010-01-01

    Retinal ganglion cells convey information by increasing their firing in response to an optimal visual stimulus or “trigger feature.” However, one class of ganglion cell responds to changes in the visual scene by decreasing its firing. These cells, termed uniformity detectors in the rabbit retina, are encountered only rarely and the synaptic mechanisms underlying their unusual responses have not been investigated. In this study, patch-clamp recordings of uniformity detectors show that the action potentials underlying the maintained firing arise within “complex spikes.” Both ON and OFF visual stimuli elicit only inhibitory synaptic input, the immediate effect of which is to suppress the maintained firing. However, this inhibition also alters the properties of the “renascent” spiking by increasing the amplitude of the spikes within each burst, suggesting that the effect may increase the efficacy of spike propagation and transmission. PMID:20212117

  3. Mitochondria mediates caspase-dependent and independent retinal cell death in Staphylococcus aureus endophthalmitis

    PubMed Central

    Singh, P K; Kumar, A

    2016-01-01

    Bacterial endophthalmitis, a vision-threatening complication of ocular surgery or trauma, is characterized by increased intraocular inflammation and retinal tissue damage. Although significant vision loss in endophthalmitis has been linked to retinal cell death, the underlying mechanisms of cell death remain elusive. In this study, using a mouse model of Staphylococcus aureus endophthalmitis and cultured human retinal Müller glia (MIO-M1 cell line), we demonstrate that S. aureus caused significant apoptotic cell death in the mouse retina and Müller glia, as evidenced by increased number of terminal dUTP nick end labeling and Annexin V and propidium iodide-positive cells. Immunohistochemistry and western blot studies revealed the reduction in mitochondrial membrane potential (JC-1 staining), release of cytochrome c into the cytosol, translocation of Bax to the mitochondria and the activation of caspase-9 and -3 in S. aureus-infected retina/retinal cells. In addition, the activation of PARP-1 and the release of apoptosis inducing factor from mitochondria was also observed in S. aureus-infected retinal cells. Inhibition studies using pan-caspase (Q-VD-OPH) and PARP-1 (DPQ) inhibitors showed significant reduction in S. aureus-induced retinal cell death both in vivo and in vitro. Together, our findings demonstrate that in bacterial endophthalmitis, retinal cells undergo apoptosis in the both caspase-dependent and independent manners, and mitochondria have a central role in this process. Hence, targeting the identified signaling pathways may provide the rationale to design therapeutic interventions to prevent bystander retinal tissue damage in bacterial endophthalmitis. PMID:27551524

  4. Mitochondria mediates caspase-dependent and independent retinal cell death in Staphylococcus aureus endophthalmitis.

    PubMed

    Singh, P K; Kumar, A

    2016-01-01

    Bacterial endophthalmitis, a vision-threatening complication of ocular surgery or trauma, is characterized by increased intraocular inflammation and retinal tissue damage. Although significant vision loss in endophthalmitis has been linked to retinal cell death, the underlying mechanisms of cell death remain elusive. In this study, using a mouse model of Staphylococcus aureus endophthalmitis and cultured human retinal Müller glia (MIO-M1 cell line), we demonstrate that S. aureus caused significant apoptotic cell death in the mouse retina and Müller glia, as evidenced by increased number of terminal dUTP nick end labeling and Annexin V and propidium iodide-positive cells. Immunohistochemistry and western blot studies revealed the reduction in mitochondrial membrane potential (JC-1 staining), release of cytochrome c into the cytosol, translocation of Bax to the mitochondria and the activation of caspase-9 and -3 in S. aureus-infected retina/retinal cells. In addition, the activation of PARP-1 and the release of apoptosis inducing factor from mitochondria was also observed in S. aureus-infected retinal cells. Inhibition studies using pan-caspase (Q-VD-OPH) and PARP-1 (DPQ) inhibitors showed significant reduction in S. aureus-induced retinal cell death both in vivo and in vitro. Together, our findings demonstrate that in bacterial endophthalmitis, retinal cells undergo apoptosis in the both caspase-dependent and independent manners, and mitochondria have a central role in this process. Hence, targeting the identified signaling pathways may provide the rationale to design therapeutic interventions to prevent bystander retinal tissue damage in bacterial endophthalmitis. PMID:27551524

  5. The Independent Probabilistic Firing of Transcription Factors: A Paradigm for Clonal Variability in the Zebrafish Retina

    PubMed Central

    Boije, Henrik; Rulands, Steffen; Dudczig, Stefanie; Simons, Benjamin D.; Harris, William A.

    2015-01-01

    Summary Early retinal progenitor cells (RPCs) in vertebrates produce lineages that vary greatly both in terms of cell number and fate composition, yet how this variability is achieved remains unknown. One possibility is that these RPCs are individually distinct and that each gives rise to a unique lineage. Another is that stochastic mechanisms play upon the determinative machinery of equipotent early RPCs to drive clonal variability. Here we show that a simple model, based on the independent firing of key fate-influencing transcription factors, can quantitatively account for the intrinsic clonal variance in the zebrafish retina and predict the distributions of neuronal cell types in clones where one or more of these fates are made unavailable. PMID:26343455

  6. Transgenic Mice Overexpressing Serum Retinol-Binding Protein Develop Progressive Retinal Degeneration through a Retinoid-Independent Mechanism

    PubMed Central

    Du, Mei; Otalora, Laura; Martin, Ashley A.; Moiseyev, Gennadiy; Vanlandingham, Phillip; Wang, Qilong; Farjo, Rafal; Yeganeh, Alexander; Quiambao, Alexander

    2015-01-01

    Serum retinol-binding protein 4 (RBP4) is the sole specific transport protein for retinol in the blood, but it is also an adipokine with retinol-independent, proinflammatory activity associated with obesity, insulin resistance, type 2 diabetes, and cardiovascular disease. Moreover, two separate studies reported that patients with proliferative diabetic retinopathy have increased serum RBP4 levels compared to patients with mild or no retinopathy, yet the effect of increased levels of RBP4 on the retina has not been studied. Here we show that transgenic mice overexpressing RBP4 (RBP4-Tg mice) develop progressive retinal degeneration, characterized by photoreceptor ribbon synapse deficiency and subsequent bipolar cell loss. Ocular retinoid and bisretinoid levels are normal in RBP4-Tg mice, demonstrating that a retinoid-independent mechanism underlies retinal degeneration. Increased expression of pro-interleukin-18 (pro-IL-18) mRNA and activated IL-18 protein and early-onset microglia activation in the retina suggest that retinal degeneration is driven by a proinflammatory mechanism. Neither chronic systemic metabolic disease nor other retinal insults are required for RBP4 elevation to promote retinal neurodegeneration, since RBP4-Tg mice do not have coincident retinal vascular pathology, obesity, dyslipidemia, or hyperglycemia. These findings suggest that elevation of serum RBP4 levels could be a risk factor for retinal damage and vision loss in nondiabetic as well as diabetic patients. PMID:26055327

  7. Attenuation of nitric oxide- and prostaglandin-independent vasodilation of retinal arterioles induced by acetylcholine in streptozotocin-treated rats.

    PubMed

    Nakazawa, Taisuke; Kaneko, Yoshiko; Mori, Asami; Saito, Maki; Sakamoto, Kenji; Nakahara, Tsutomu; Ishii, Kunio

    2007-03-01

    Diabetes alters retinal hemodynamics, but little is known about the impact of diabetes on the role of endothelium-derived hyperpolarizing factor (EDHF) in the regulation of retinal circulation. Therefore, we examined how diabetes affects the nitric oxide- and prostaglandin-independent vasodilation of retinal arterioles induced by acetylcholine. Male Wistar rats were treated with streptozotocin (80 mg/kg, i.p.) and experiments were performed 6-8 weeks later. Under artificial ventilation, rats were treated with tetrodotoxin (100 microg/kg, i.v.) to eliminate any nerve activity and prevent movement of the eye. Methoxamine was used to maintain adequate systemic circulation. Fundus images were captured by a digital camera that was equipped with a special objective lens. The vasodilator responses of retinal arterioles were assessed by measuring changes in diameters of the vessels. In streptozotocin-induced diabetic rats and the age-matched controls, acetylcholine increased diameters of retinal arterioles in a dose-dependent manner. The vasodilator responses to acetylcholine in diabetic rats were smaller than those in control rats. The nitric oxide- and prostaglandin-independent vasodilation of retinal arterioles observed under treatment with combination of N(G)-nitro-l-arginine methyl ester (30 mg/kg, i.v.) and indomethacin (5 mg/kg, i.v.) were also attenuated by diabetes. Diabetes did not alter the dilator responses of retinal arterioles to sodium nitroprusside and forskolin. These results suggest that diabetes impairs EDHF-mediated vasodilation of retinal arterioles induced by acetylcholine. The impaired EDHF-mediated vasodilation may contribute to alteration of retinal hemodynamics in diabetes. PMID:17079193

  8. The Association of Type 2 Diabetes Mellitus with Cerebral Gray Matter Volume Is Independent of Retinal Vascular Architecture and Retinopathy

    PubMed Central

    Moran, C.; Tapp, R. J.; Hughes, A. D.; Magnussen, C. G.; Blizzard, L.; Phan, T. G.; Beare, R.; Witt, N.; Venn, A.; Münch, G.; Amaratunge, B. C.; Srikanth, V.

    2016-01-01

    It is uncertain whether small vessel disease underlies the relationship between Type 2 Diabetes Mellitus (T2DM) and brain atrophy. We aimed to study whether retinal vascular architecture, as a proxy for cerebral small vessel disease, may modify or mediate the associations of T2DM with brain volumes. In this cross-sectional study using Magnetic Resonance Imaging (MRI) scans and retinal photographs in 451 people with and without T2DM, we measured brain volumes, geometric measures of retinal vascular architecture, clinical retinopathy, and MRI cerebrovascular lesions. There were 270 people with (mean age 67.3 years) and 181 without T2DM (mean age 72.9 years). T2DM was associated with lower gray matter volume (p = 0.008). T2DM was associated with greater arteriolar diameter (p = 0.03) and optimality ratio (p = 0.04), but these associations were attenuated by adjustments for age and sex. Only optimality ratio was associated with lower gray matter volume (p = 0.03). The inclusion of retinal measures in regression models did not attenuate the association of T2DM with gray matter volume. The association of T2DM with lower gray matter volume was independent of retinal vascular architecture and clinical retinopathy. Retinal vascular measures or retinopathy may not be sufficiently sensitive to confirm a microvascular basis for T2DM-related brain atrophy. PMID:27314049

  9. The Association of Type 2 Diabetes Mellitus with Cerebral Gray Matter Volume Is Independent of Retinal Vascular Architecture and Retinopathy.

    PubMed

    Moran, C; Tapp, R J; Hughes, A D; Magnussen, C G; Blizzard, L; Phan, T G; Beare, R; Witt, N; Venn, A; Münch, G; Amaratunge, B C; Srikanth, V

    2016-01-01

    It is uncertain whether small vessel disease underlies the relationship between Type 2 Diabetes Mellitus (T2DM) and brain atrophy. We aimed to study whether retinal vascular architecture, as a proxy for cerebral small vessel disease, may modify or mediate the associations of T2DM with brain volumes. In this cross-sectional study using Magnetic Resonance Imaging (MRI) scans and retinal photographs in 451 people with and without T2DM, we measured brain volumes, geometric measures of retinal vascular architecture, clinical retinopathy, and MRI cerebrovascular lesions. There were 270 people with (mean age 67.3 years) and 181 without T2DM (mean age 72.9 years). T2DM was associated with lower gray matter volume (p = 0.008). T2DM was associated with greater arteriolar diameter (p = 0.03) and optimality ratio (p = 0.04), but these associations were attenuated by adjustments for age and sex. Only optimality ratio was associated with lower gray matter volume (p = 0.03). The inclusion of retinal measures in regression models did not attenuate the association of T2DM with gray matter volume. The association of T2DM with lower gray matter volume was independent of retinal vascular architecture and clinical retinopathy. Retinal vascular measures or retinopathy may not be sufficiently sensitive to confirm a microvascular basis for T2DM-related brain atrophy. PMID:27314049

  10. Connexin 36 and rod bipolar cell independent rod pathways drive retinal ganglion cells and optokinetic reflexes.

    PubMed

    Cowan, Cameron S; Abd-El-Barr, Muhammad; van der Heijden, Meike; Lo, Eric M; Paul, David; Bramblett, Debra E; Lem, Janis; Simons, David L; Wu, Samuel M

    2016-02-01

    Rod pathways are a parallel set of synaptic connections which enable night vision by relaying and processing rod photoreceptor light responses. We use dim light stimuli to isolate rod pathway contributions to downstream light responses then characterize these contributions in knockout mice lacking rod transducin-α (Trα), or certain pathway components associated with subsets of rod pathways. These comparisons reveal that rod pathway driven light sensitivity in retinal ganglion cells (RGCs) is entirely dependent on Trα, but partially independent of connexin 36 (Cx36) and rod bipolar cells. Pharmacological experiments show that rod pathway-driven and Cx36-independent RGC ON responses are also metabotropic glutamate receptor 6-dependent. To validate the RGC findings in awake, behaving animals we measured optokinetic reflexes (OKRs), which are sensitive to changes in ON pathways. Scotopic OKR contrast sensitivity was lost in Trα(-/-) mice, but indistinguishable from controls in Cx36(-/-) and rod bipolar cell knockout mice. Mesopic OKRs were also altered in mutant mice: Trα(-/-) mice had decreased spatial acuity, rod BC knockouts had decreased sensitivity, and Cx36(-/-) mice had increased sensitivity. These results provide compelling evidence against the complete Cx36 or rod BC dependence of night vision's ON component. Further, the findings suggest the parallel nature of rod pathways provides considerable redundancy to scotopic light sensitivity but distinct contributions to mesopic responses through complicated interactions with cone pathways. PMID:26718442

  11. mTORC1-Independent Reduction of Retinal Protein Synthesis in Type 1 Diabetes

    PubMed Central

    Losiewicz, Mandy K.; Pennathur, Subramaniam; Jefferson, Leonard S.; Kimball, Scot R.; Abcouwer, Steven F.; Gardner, Thomas W.

    2014-01-01

    Poorly controlled diabetes has long been known as a catabolic disorder with profound loss of muscle and fat body mass resulting from a simultaneous reduction in protein synthesis and enhanced protein degradation. By contrast, retinal structure is largely maintained during diabetes despite reduced Akt activity and increased rate of cell death. Therefore, we hypothesized that retinal protein turnover is regulated differently than in other insulin-sensitive tissues, such as skeletal muscle. Ins2Akita diabetic mice and streptozotocin-induced diabetic rats exhibited marked reductions in retinal protein synthesis matched by a concomitant reduction in retinal protein degradation associated with preserved retinal mass and protein content. The reduction in protein synthesis depended on both hyperglycemia and insulin deficiency, but protein degradation was only reversed by normalization of hyperglycemia. The reduction in protein synthesis was associated with diminished protein translation efficiency but, surprisingly, not with reduced activity of the mTORC1/S6K1/4E-BP1 pathway. Instead, diabetes induced a specific reduction of mTORC2 complex activity. These findings reveal distinctive responses of diabetes-induced retinal protein turnover compared with muscle and liver that may provide a new means to ameliorate diabetic retinopathy. PMID:24740573

  12. Independent and synergistic interaction of retinal G-protein subunits with bovine rhodopsin measured by surface plasmon resonance.

    PubMed Central

    Clark, W A; Jian, X; Chen, L; Northup, J K

    2001-01-01

    We have used surface plasmon resonance (SPR) measurements for the kinetic analysis of G-protein-receptor interaction monitored in real time. Functionally active rhodopsin was immobilized on an SPR surface, with full retention of biochemical specific activity for catalysis of nucleotide exchange on the retinal G-protein alpha subunit, via binding to immobilized concanavalin A. The binding interactions of bovine retinal alpha(t) and beta(1)gamma(1) subunits with rhodopsin measured by SPR were profoundly synergistic. Synergistic binding of the retinal G-protein subunits to rhodopsin was not observed for guanosine 5'-[gamma-thio]triphosphate-bound Galpha(t), nor was binding observed with squid retinal Galpha(q), which is not activated by bovine rhodopsin. The binding affinity (336+/-171 nM; mean value+/-S.D.) of retinal betagamma for rhodopsin in the presence of retinal alpha subunit measured by SPR confirmed the apparent affinity of 254 nM determined previously by nucleotide exchange assays. Binding of beta(1)gamma(1), beta(1)gamma(2), and beta(1)gamma(8-olf) dimers to rhodopsin, independently of the alpha subunit, was readily observable by SPR. Further, these dimers, differing only in their gamma subunit compositions, displayed markedly distinct binding affinities and kinetics. The beta(1)gamma(2) dimer bound with a kinetically determined K(d) of 13+/-3 nM, a value nearly identical with the biochemically determined K(1/2) of 10 nM. The physiologically appropriate beta(1)gamma(1) displayed rapid association and dissociation kinetics, whereas the other beta(1)gamma dimers dissociated at a rate less than 1/100 as fast. Thus rhodopsin interaction with its native signalling partners is both rapid and transient, whereas the interaction of rhodopsin with heterologous Gbetagamma dimers is markedly prolonged. These results suggest that the duration of a G-protein-coupled receptor signalling event is an intrinsic property of the G-protein coupling partners; in particular, the

  13. Hartwell brings gas-fired independent power to Georgia

    SciTech Connect

    1996-01-01

    This exempt wholesale generator is the first major independent power producer in the state, and its power purchase agreement is one of the first signed with a Rural Electrification Administration utility. Fuel access made siting here a natural. In its first 22 months of operation, the Hartwell Energy Project, Hart County, Ga, has already put its advanced, high-temperature gas turbines through a vigorous workout: the strenuous dispatch regimen calls for multiple starts per day, and for on-line time that varies anywhere from 20 minutes to 18 hours at a stretch. And once on the grid, the turbines haven`t sauntered along at low power levels--97% of the operating time has been at full load. In spite of the demanding dispatch schedule, Hartwell has achieved a 98% availability factor since commercial startup. Being located at the interaction of major gas and oil pipelines, the 300-MW peaking facility`s fuel picture is one of inherent flexibility. Its two simple-cycle 7FA gas turbine/generators, supplied by General Electric Co (GE), Schenectady, NY, are dual-fuel capable, although to date, fuel oil has been burned only for testing purposes.

  14. Effect of correlated lateral geniculate nucleus firing rates on predictions for monocular eye closure versus monocular retinal inactivation

    NASA Astrophysics Data System (ADS)

    Blais, Brian S.; Cooper, Leon N.; Shouval, Harel Z.

    2009-12-01

    Monocular deprivation experiments can be used to distinguish between different ideas concerning properties of cortical synaptic plasticity. Monocular deprivation by lid suture causes a rapid disconnection of the deprived eye connected to cortical neurons whereas total inactivation of the deprived eye produces much less of an ocular dominance shift. In order to understand these results one needs to know how lid suture and retinal inactivation affect neurons in the lateral geniculate nucleus (LGN) that provide the cortical input. Recent experimental results by Linden showed that monocular lid suture and monocular inactivation do not change the mean firing rates of LGN neurons but that lid suture reduces correlations between adjacent neurons whereas monocular inactivation leads to correlated firing. These, somewhat surprising, results contradict assumptions that have been made to explain the outcomes of different monocular deprivation protocols. Based on these experimental results we modify our assumptions about inputs to cortex during different deprivation protocols and show their implications when combined with different cortical plasticity rules. Using theoretical analysis, random matrix theory and simulations we show that high levels of correlations reduce the ocular dominance shift in learning rules that depend on homosynaptic depression (i.e., Bienenstock-Cooper-Munro type rules), consistent with experimental results, but have the opposite effect in rules that depend on heterosynaptic depression (i.e., Hebbian/principal component analysis type rules).

  15. Independent component analysis for the detection of in vivo intrinsic signals from an optical imager of retinal function

    NASA Astrophysics Data System (ADS)

    Barriga, Eduardo S.; Pattichis, Marios; Abramoff, Michael; T'so, Dan; Kwon, Young; Kardon, Randy; Soliz, Peter

    2007-02-01

    To overcome the difficulty in detection of loss of retinal activity, a functional-Retinal Imaging Device (f-RID) was developed. The device, which is based on a modified fundus camera, seeks to detect changes in optical signals that reflect functional changes in the retina. Measured changes in reflectance in response to the visual stimulus are on the order of 0.1% to 1% of the total reflected intensity level, which makes the functional signal difficult to detect by standard methods because it is masked by other physiological signals and by noise. In this paper, we present a new Independent Component Analysis (ICA) algorithm used to analyze the video sequences from a set of experiments with different patterned stimuli from cats and humans. The ICA algorithm with priors (ICA-P) uses information about the stimulation paradigms to increase the signal detection thresholds when compared to traditional ICA algorithms. The results of the analysis show that we can detect signal levels as low as 0.01% of the total reflected intensity. Also, improvement of up to 30dB in signal detection over traditional ICA algorithms is achieved. The study found that in more than 80% of the in-vivo experiments the patterned stimuli effects on the retina can be detected and extracted.

  16. Hop/STI1 modulates retinal proliferation and cell death independent of PrP{sup C}

    SciTech Connect

    Arruda-Carvalho, Maithe; Njaine, Brian; Silveira, Mariana S.; Linden, Rafael; Chiarini, Luciana B. . E-mail: chiarini@biof.ufrj.br

    2007-09-21

    Hop/STI1 is a co-chaperone adaptor protein for Hsp70/Hsp90 complexes. Hop/STI1 is found extracellularly and modulates cell death and differentiation through interaction with the prion protein (PrP{sup C}). Here, we investigated the expression of hop/STI1 and its role upon cell proliferation and cell death in the developing retina. Hop/STI1 is more expressed in developing rat retina than in the mature tissue. Hop/STI1 blocks retinal cell death in the neuroblastic layer (NBL) in a PrP{sup C} dependent manner, but failed to protect ganglion cells against axotomy-induced cell death. An antibody raised against hop/STI1 ({alpha}-STI1) blocked both ganglion cell and NBL cell death independent of PrP{sup C}. cAMP/PKA, ERK, PI3K and PKC signaling pathways were not involved in these effects. Hop/STI1 treatment reduced proliferation, while {alpha}-STI1 increased proliferation in the developing retina, both independent of PrP{sup C}. We conclude that hop/STI1 can modulate both proliferation and cell death in the developing retina independent of PrP{sup C}.

  17. Mutation Independent Rescue of a Novel Mouse Model of Retinitis Pigmentosa

    PubMed Central

    Greenwald, David L.; Cashman, Siobhan M.; Kumar-Singh, Rajendra

    2014-01-01

    Retinitis pigmentosa (RP) is the leading cause of inherited blindness in the developed world, affecting approximately 1 in 3,000 individuals. While there is currently no cure for RP, the genetic pathology has been well established. In this study we developed a novel mouse model of RP (huRhoP347S) expressing a pathogenic human rhodopsin gene with a Pro347Ser mutation on a rhodopsin knockout background. These mice undergo severe retinal degeneration at one month of age. In contrast to prior studies, this model was administered a gene therapy treatment at 19 days post natal. We evaluated several self-complementary adeno-associated virus serotypes for photoreceptor tropism including scAAV2/2, scAAV2/5, scAAV2/6.2 and scAAV2/9, and found that scAAV2/9 transduced photoreceptors with greater efficiency and expression than other vectors. We engineered a scAAV2/9 vector to contain a microRNA sequence specifically targeting the human rhodopsin gene and demonstrated its ability to silence rhodopsin by 60.2 ± 8.2% in vitro. In addition, we constructed a scAAV2/9 vector to contain a replacement “codon-modified” rhodopsin transgene (RhoR2) that was resistant to degradation by the microRNA. We found that delivery of the RhoR2 by scAAV2/9 is capable of restoring vision to rhodopsin knockout mice, and rescuing our novel transgenic huRhoP347S mouse model of dominant RP. Average a-wave responses of RhoR2-injected eyes were 1.8-fold higher than those of control-injected eyes. We found that delivery of the microRNA and replacement rhodopsin in a 1:2 ratio produced an average ERG a-wave response of 17.4 ± 2.9 μV compared to 6.5 ± 2.8 μV for eyes injected with negative control virus. PMID:22809998

  18. Retinitis Pigmentosa

    MedlinePlus

    ... Action You are here Home › Retinal Diseases Listen Retinitis Pigmentosa What is retinitis pigmentosa? What are the symptoms? ... available? Are there any related diseases? What is retinitis pigmentosa? Retinitis pigmentosa (RP) refers to a group of ...

  19. Fires

    MedlinePlus

    Whether a fire happens in your home or in the wild, it can be very dangerous. Fire spreads quickly. There is no time to gather ... a phone call. In just two minutes, a fire can become life-threatening. In five minutes, a ...

  20. Retinal Cell Death Caused by Sodium Iodate Involves Multiple Caspase-Dependent and Caspase-Independent Cell-Death Pathways

    PubMed Central

    Balmer, Jasmin; Zulliger, Rahel; Roberti, Stefano; Enzmann, Volker

    2015-01-01

    Herein, we have investigated retinal cell-death pathways in response to the retina toxin sodium iodate (NaIO3) both in vivo and in vitro. C57/BL6 mice were treated with a single intravenous injection of NaIO3 (35 mg/kg). Morphological changes in the retina post NaIO3 injection in comparison to untreated controls were assessed using electron microscopy. Cell death was determined by TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining. The activation of caspases and calpain was measured using immunohistochemistry. Additionally, cytotoxicity and apoptosis in retinal pigment epithelial (RPE) cells, primary retinal cells, and the cone photoreceptor (PRC) cell line 661W were assessed in vitro after NaIO3 treatment using the ApoToxGlo™ assay. The 7-AAD/Annexin-V staining was performed and necrostatin (Nec-1) was administered to the NaIO3-treated cells to confirm the results. In vivo, degenerating RPE cells displayed a rounded shape and retracted microvilli, whereas PRCs featured apoptotic nuclei. Caspase and calpain activity was significantly upregulated in retinal sections and protein samples from NaIO3-treated animals. In vitro, NaIO3 induced necrosis in RPE cells and apoptosis in PRCs. Furthermore, Nec-1 significantly decreased NaIO3-induced RPE cell death, but had no rescue effect on treated PRCs. In summary, several different cell-death pathways are activated in retinal cells as a result of NaIO3. PMID:26151844

  1. Human Brain Expansion during Evolution Is Independent of Fire Control and Cooking.

    PubMed

    Cornélio, Alianda M; de Bittencourt-Navarrete, Ruben E; de Bittencourt Brum, Ricardo; Queiroz, Claudio M; Costa, Marcos R

    2016-01-01

    What makes humans unique? This question has fascinated scientists and philosophers for centuries and it is still a matter of intense debate. Nowadays, human brain expansion during evolution has been acknowledged to explain our empowered cognitive capabilities. The drivers for such accelerated expansion remain, however, largely unknown. In this sense, studies have suggested that the cooking of food could be a pre-requisite for the expansion of brain size in early hominins. However, this appealing hypothesis is only supported by a mathematical model suggesting that the increasing number of neurons in the brain would constrain body size among primates due to a limited amount of calories obtained from diets. Here, we show, by using a similar mathematical model, that a tradeoff between body mass and the number of brain neurons imposed by dietary constraints during hominin evolution is unlikely. Instead, the predictable number of neurons in the hominin brain varies much more in function of foraging efficiency than body mass. We also review archeological data to show that the expansion of the brain volume in the hominin lineage is described by a linear function independent of evidence of fire control, and therefore, thermal processing of food does not account for this phenomenon. Finally, we report experiments in mice showing that thermal processing of meat does not increase its caloric availability in mice. Altogether, our data indicate that cooking is neither sufficient nor necessary to explain hominin brain expansion. PMID:27199631

  2. Human Brain Expansion during Evolution Is Independent of Fire Control and Cooking

    PubMed Central

    Cornélio, Alianda M.; de Bittencourt-Navarrete, Ruben E.; de Bittencourt Brum, Ricardo; Queiroz, Claudio M.; Costa, Marcos R.

    2016-01-01

    What makes humans unique? This question has fascinated scientists and philosophers for centuries and it is still a matter of intense debate. Nowadays, human brain expansion during evolution has been acknowledged to explain our empowered cognitive capabilities. The drivers for such accelerated expansion remain, however, largely unknown. In this sense, studies have suggested that the cooking of food could be a pre-requisite for the expansion of brain size in early hominins. However, this appealing hypothesis is only supported by a mathematical model suggesting that the increasing number of neurons in the brain would constrain body size among primates due to a limited amount of calories obtained from diets. Here, we show, by using a similar mathematical model, that a tradeoff between body mass and the number of brain neurons imposed by dietary constraints during hominin evolution is unlikely. Instead, the predictable number of neurons in the hominin brain varies much more in function of foraging efficiency than body mass. We also review archeological data to show that the expansion of the brain volume in the hominin lineage is described by a linear function independent of evidence of fire control, and therefore, thermal processing of food does not account for this phenomenon. Finally, we report experiments in mice showing that thermal processing of meat does not increase its caloric availability in mice. Altogether, our data indicate that cooking is neither sufficient nor necessary to explain hominin brain expansion. PMID:27199631

  3. Cytomegalovirus retinitis

    MedlinePlus

    ... to prevent its return. Alternative Names Cytomegalovirus retinitis Images Eye CMV retinitis CMV (cytomegalovirus) References Crumpacker CS. ... 5. Read More Antibody HIV/AIDS Immune response Retinal detachment Systemic WBC count Update Date 12/10/ ...

  4. Retinitis Pigmentosa.

    ERIC Educational Resources Information Center

    Carr, Ronald E.

    1979-01-01

    The author describes the etiology of retinitis pigmentosa, a visual dysfunction which results from progressive loss of the retinal photoreceptors. Sections address signs and symptoms, ancillary findings, heredity, clinical diagnosis, therapy, and research. (SBH)

  5. PRMT1 and PRMT4 Regulate Oxidative Stress-Induced Retinal Pigment Epithelial Cell Damage in SIRT1-Dependent and SIRT1-Independent Manners

    PubMed Central

    Kim, Dong-Il; Park, Min-Jung; Choi, Joo-Hee; Kim, In-Seon; Han, Ho-Jae; Yoon, Kyung-Chul; Park, Sang-Woo; Lee, Min-Young; Oh, Ki-Seok; Park, Soo-Hyun

    2015-01-01

    Oxidative stress-induced retinal pigment epithelial (RPE) cell damage is involved in the progression of diabetic retinopathy. Arginine methylation catalyzed by protein arginine methyltransferases (PRMTs) has emerged as an important histone modification involved in diverse diseases. Sirtuin (SIRT1) is a protein deacetylase implicated in the onset of metabolic diseases. Therefore, we examined the roles of type I PRMTs and their relationship with SIRT1 in human RPE cells under H2O2-induced oxidative stress. H2O2 treatment increased PRMT1 and PRMT4 expression but decreased SIRT1 expression. Similar to H2O2 treatment, PRMT1 or PRMT4 overexpression increased RPE cell damage. Moreover, the H2O2-induced RPE cell damage was attenuated by PRMT1 or PRMT4 knockdown and SIRT1 overexpression. In this study, we revealed that SIRT1 expression was regulated by PRMT1 but not by PRMT4. Finally, we found that PRMT1 and PRMT4 expression is increased in the RPE layer of streptozotocin-treated rats. Taken together, we demonstrated that oxidative stress induces apoptosis both via PRMT1 in a SIRT1-dependent manner and via PRMT4 in a SIRT1-independent manner. The inhibition of the expression of type I PRMTs, especially PRMT1 and PRMT4, and increased SIRT1 could be therapeutic approaches for diabetic retinopathy. PMID:26583059

  6. High resolution optoelectronic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Loudin, Jim; Dinyari, Rostam; Huie, Phil; Butterwick, Alex; Peumans, Peter; Palanker, Daniel

    2009-02-01

    Electronic retinal prostheses seek to restore sight in patients with retinal degeneration by delivering pulsed electric currents to retinal neurons via an array of microelectrodes. Most implants use inductive or optical transmission of information and power to an intraocular receiver, with decoded signals subsequently distributed to retinal electrodes through an intraocular cable. Surgical complexity could be minimized by an "integrated" prosthesis, in which both power and data are delivered directly to the stimulating array without any discrete components or cables. We present here an integrated retinal prosthesis system based on a photodiode array implant. Video frames are processed and imaged onto the retinal implant by a video goggle projection system operating at near-infrared wavelengths (~ 900 nm). Photodiodes convert light into pulsed electric current, with charge injection maximized by specially optimized series photodiode circuits. Prostheses of three different pixel densities (16 pix/mm2, 64 pix/mm2, and 256 pix/mm2) have been designed, simulated, and prototyped. Retinal tissue response to subretinal implants made of various materials has been investigated in RCS rats. The resulting prosthesis can provide sufficient charge injection for high resolution retinal stimulation without the need for implantation of any bulky discrete elements such as coils or tethers. In addition, since every pixel functions independently, pixel arrays may be placed separately in the subretinal space, providing visual stimulation to a larger field of view.

  7. Retinal Prosthesis

    PubMed Central

    Weiland, James D.; Humayun, Mark S.

    2015-01-01

    Retinal prosthesis have been translated from the laboratory to the clinical over the past two decades. Currently, two devices have regulatory approval for the treatment of retinitis pigmentosa. These devices provide partial sight restoration and patients use this improved vision in their everyday lives. Improved mobility and object detection are some of the more notable findings from the clinical trials. However, significant vision restoration will require both better technology and improved understanding of the interaction between electrical stimulation and the retina. This paper reviews the recent clinical trials, highlights technology breakthroughs that will contribute to next generation of retinal prostheses. PMID:24710817

  8. Foveomacular retinitis.

    PubMed Central

    Kuming, B S

    1986-01-01

    A group of patients is described who developed the clinical features of foveomacular retinitis. No causative factors were isolated, and all patients strongly denied any type of sun gazing. It is possible that there is a group of patients who have the features of foveomacular retinitis but have not had any direct exposure to the sun. These patients would then constitute a primary type of foveomacular retinitis, as opposed to a secondary type which has a known cause and is synonymous with solar retinopathy. Images PMID:3790482

  9. Retinal Disorders

    MedlinePlus

    ... be serious enough to cause blindness. Examples are Macular degeneration - a disease that destroys your sharp, central vision Diabetic eye disease Retinal detachment - a medical emergency, when the retina is ... children. Macular pucker - scar tissue on the macula Macular hole - ...

  10. Retinal Detachment

    MedlinePlus

    ... immediately. Treatment How is retinal detachment treated? Small holes and tears are treated with laser surgery or ... laser surgery tiny burns are made around the hole to “weld” the retina back into place. Cryopexy ...

  11. Di-retinoid-pyridinium-ethanolamine (A2E) Accumulation and the Maintenance of the Visual Cycle Are Independent of Atg7-mediated Autophagy in the Retinal Pigmented Epithelium.

    PubMed

    Perusek, Lindsay; Sahu, Bhubanananda; Parmar, Tanu; Maeno, Hiroshi; Arai, Eisuke; Le, Yun-Zheng; Subauste, Carlos S; Chen, Yu; Palczewski, Krzysztof; Maeda, Akiko

    2015-11-27

    Autophagy is an evolutionarily conserved catabolic mechanism that relieves cellular stress by removing/recycling damaged organelles and debris through the action of lysosomes. Compromised autophagy has been implicated in many neurodegenerative diseases, including retinal degeneration. Here we examined retinal phenotypes resulting from RPE-specific deletion of the autophagy regulatory gene Atg7 by generating Atg7(flox/flox);VMD2-rtTA-cre+ mice to determine whether autophagy is essential for RPE functions including retinoid recycling. Atg7-deficient RPE displayed abnormal morphology with increased RPE thickness, cellular debris and vacuole formation indicating that autophagy is important in maintaining RPE homeostasis. In contrast, 11-cis-retinal content, ERGs and retinal histology were normal in mice with Atg7-deficient RPE in both fasted and fed states. Because A2E accumulation in the RPE is associated with pathogenesis of both Stargardt disease and age-related macular degeneration (AMD) in humans, deletion of Abca4 was introduced into Atg7(flox/flox);VMD2-rtTA-cre+ mice to investigate the role of autophagy during A2E accumulation. Comparable A2E concentrations were detected in the eyes of 6-month-old mice with and without Atg7 from both Abca4(-/-) and Abca4(+/+) backgrounds. To identify other autophagy-related molecules involved in A2E accumulation, we performed gene expression array analysis on A2E-treated human RPE cells and found up-regulation of four autophagy related genes; DRAM1, NPC1, CASP3, and EIF2AK3/PERK. These observations indicate that Atg7-mediated autophagy is dispensable for retinoid recycling and A2E deposition; however, autophagy plays a role in coping with stress caused by A2E accumulation. PMID:26468292

  12. Gain-of-function nature of Cav1.4 L-type calcium channels alters firing properties of mouse retinal ganglion cells

    PubMed Central

    Knoflach, Dagmar; Schicker, Klaus; Glösmann, Martin; Koschak, Alexandra

    2015-01-01

    Proper function of Cav1.4 L-type calcium channels is crucial for neurotransmitter release in the retina. Our understanding about how different levels of Cav1.4 channel activity affect retinal function is still limited. In the gain-of-function mouse model Cav1.4-IT we expected a reduction in the photoreceptor dynamic range but still transmission toward retinal ganglion cells. A fraction of Cav1.4-IT ganglion cells responded to light stimulation in multielectrode array recordings from whole-mounted retinas, but showed a significantly delayed response onset. Another significant number of cells showed higher activity in darkness. In addition to structural remodeling observed at the first retinal synapse of Cav1.4-IT mice the functional data suggested a loss of contrast enhancement, a fundamental feature of our visual system. In fact, Cav1.4-IT mouse retinas showed a decline in spatial response and changes in their contrast sensitivity profile. Photoreceptor degeneration was obvious from the nodular structure of cone axons and enlarged pedicles which partly moved toward the outer nuclear layer. Loss of photoreceptors was also expressed as reduced expression of proteins involved in chemical and electrical transmission, as such metabotropic glutamate receptor mGluR6 and the gap junction protein Connexin 36. Such gross changes in retinal structure and function could also explain the diminished visual performance of CSNB2 patients. The expression pattern of the plasma-membrane calcium ATPase 1 which participates in the maintenance of the intracellular calcium homeostasis in photoreceptors was changed in Cav1.4-IT mice. This might be part of a protection mechanism against increased calcium influx, as this is suggested for Cav1.4-IT channels. PMID:26274509

  13. Gain-of-function nature of Cav1.4 L-type calcium channels alters firing properties of mouse retinal ganglion cells.

    PubMed

    Knoflach, Dagmar; Schicker, Klaus; Glösmann, Martin; Koschak, Alexandra

    2015-01-01

    Proper function of Cav1.4 L-type calcium channels is crucial for neurotransmitter release in the retina. Our understanding about how different levels of Cav1.4 channel activity affect retinal function is still limited. In the gain-of-function mouse model Cav1.4-IT we expected a reduction in the photoreceptor dynamic range but still transmission toward retinal ganglion cells. A fraction of Cav1.4-IT ganglion cells responded to light stimulation in multielectrode array recordings from whole-mounted retinas, but showed a significantly delayed response onset. Another significant number of cells showed higher activity in darkness. In addition to structural remodeling observed at the first retinal synapse of Cav1.4-IT mice the functional data suggested a loss of contrast enhancement, a fundamental feature of our visual system. In fact, Cav1.4-IT mouse retinas showed a decline in spatial response and changes in their contrast sensitivity profile. Photoreceptor degeneration was obvious from the nodular structure of cone axons and enlarged pedicles which partly moved toward the outer nuclear layer. Loss of photoreceptors was also expressed as reduced expression of proteins involved in chemical and electrical transmission, as such metabotropic glutamate receptor mGluR6 and the gap junction protein Connexin 36. Such gross changes in retinal structure and function could also explain the diminished visual performance of CSNB2 patients. The expression pattern of the plasma-membrane calcium ATPase 1 which participates in the maintenance of the intracellular calcium homeostasis in photoreceptors was changed in Cav1.4-IT mice. This might be part of a protection mechanism against increased calcium influx, as this is suggested for Cav1.4-IT channels. PMID:26274509

  14. Computing Complex Visual Features with Retinal Spike Times

    PubMed Central

    Sompolinsky, Haim; Meister, Markus

    2013-01-01

    Neurons in sensory systems can represent information not only by their firing rate, but also by the precise timing of individual spikes. For example, certain retinal ganglion cells, first identified in the salamander, encode the spatial structure of a new image by their first-spike latencies. Here we explore how this temporal code can be used by downstream neural circuits for computing complex features of the image that are not available from the signals of individual ganglion cells. To this end, we feed the experimentally observed spike trains from a population of retinal ganglion cells to an integrate-and-fire model of post-synaptic integration. The synaptic weights of this integration are tuned according to the recently introduced tempotron learning rule. We find that this model neuron can perform complex visual detection tasks in a single synaptic stage that would require multiple stages for neurons operating instead on neural spike counts. Furthermore, the model computes rapidly, using only a single spike per afferent, and can signal its decision in turn by just a single spike. Extending these analyses to large ensembles of simulated retinal signals, we show that the model can detect the orientation of a visual pattern independent of its phase, an operation thought to be one of the primitives in early visual processing. We analyze how these computations work and compare the performance of this model to other schemes for reading out spike-timing information. These results demonstrate that the retina formats spatial information into temporal spike sequences in a way that favors computation in the time domain. Moreover, complex image analysis can be achieved already by a simple integrate-and-fire model neuron, emphasizing the power and plausibility of rapid neural computing with spike times. PMID:23301021

  15. Retinal detachment

    MedlinePlus

    ... of the first symptoms of new flashes of light and floaters. ... diabetes. See your eye care specialist once a year. You may need more frequent visits if you have risk factors for retinal detachment. Be alert to symptoms of new flashes of light and floaters.

  16. Directional summation in non-direction selective retinal ganglion cells.

    PubMed

    Abbas, Syed Y; Hamade, Khaldoun C; Yang, Ellen J; Nawy, Scott; Smith, Robert G; Pettit, Diana L

    2013-01-01

    Retinal ganglion cells receive inputs from multiple bipolar cells which must be integrated before a decision to fire is made. Theoretical studies have provided clues about how this integration is accomplished but have not directly determined the rules regulating summation of closely timed inputs along single or multiple dendrites. Here we have examined dendritic summation of multiple inputs along On ganglion cell dendrites in whole mount rat retina. We activated inputs at targeted locations by uncaging glutamate sequentially to generate apparent motion along On ganglion cell dendrites in whole mount retina. Summation was directional and dependent13 on input sequence. Input moving away from the soma (centrifugal) resulted in supralinear summation, while activation sequences moving toward the soma (centripetal) were linear. Enhanced summation for centrifugal activation was robust as it was also observed in cultured retinal ganglion cells. This directional summation was dependent on hyperpolarization activated cyclic nucleotide-gated (HCN) channels as blockade with ZD7288 eliminated directionality. A computational model confirms that activation of HCN channels can override a preference for centripetal summation expected from cell anatomy. This type of direction selectivity could play a role in coding movement similar to the axial selectivity seen in locust ganglion cells which detect looming stimuli. More generally, these results suggest that non-directional retinal ganglion cells can discriminate between input sequences independent of the retina network. PMID:23516351

  17. Directional Summation in Non-direction Selective Retinal Ganglion Cells

    PubMed Central

    Abbas, Syed Y.; Hamade, Khaldoun C.; Yang, Ellen J.; Nawy, Scott; Smith, Robert G.; Pettit, Diana L.

    2013-01-01

    Retinal ganglion cells receive inputs from multiple bipolar cells which must be integrated before a decision to fire is made. Theoretical studies have provided clues about how this integration is accomplished but have not directly determined the rules regulating summation of closely timed inputs along single or multiple dendrites. Here we have examined dendritic summation of multiple inputs along On ganglion cell dendrites in whole mount rat retina. We activated inputs at targeted locations by uncaging glutamate sequentially to generate apparent motion along On ganglion cell dendrites in whole mount retina. Summation was directional and dependent13 on input sequence. Input moving away from the soma (centrifugal) resulted in supralinear summation, while activation sequences moving toward the soma (centripetal) were linear. Enhanced summation for centrifugal activation was robust as it was also observed in cultured retinal ganglion cells. This directional summation was dependent on hyperpolarization activated cyclic nucleotide-gated (HCN) channels as blockade with ZD7288 eliminated directionality. A computational model confirms that activation of HCN channels can override a preference for centripetal summation expected from cell anatomy. This type of direction selectivity could play a role in coding movement similar to the axial selectivity seen in locust ganglion cells which detect looming stimuli. More generally, these results suggest that non-directional retinal ganglion cells can discriminate between input sequences independent of the retina network. PMID:23516351

  18. Grid cells in rat entorhinal cortex encode physical space with independent firing fields and phase precession at the single-trial level

    PubMed Central

    Reifenstein, Eric T.; Kempter, Richard; Schreiber, Susanne; Stemmler, Martin B.; Herz, Andreas V. M.

    2012-01-01

    When a rat moves, grid cells in its entorhinal cortex become active in multiple regions of the external world that form a hexagonal lattice. As the animal traverses one such “firing field,” spikes tend to occur at successively earlier theta phases of the local field potential. This phenomenon is called phase precession. Here, we show that spike phases provide 80% more spatial information than spike counts and that they improve position estimates from single neurons down to a few centimeters. To understand what limits the resolution and how variable spike phases are across different field traversals, we analyze spike trains run by run. We find that the multiple firing fields of a grid cell operate as independent elements for encoding physical space. In addition, phase precession is significantly stronger than the pooled-run data suggest. Despite the inherent stochasticity of grid-cell firing, phase precession is therefore a robust phenomenon at the single-trial level, making a theta-phase code for spatial navigation feasible. PMID:22474395

  19. Retinal Detachment Vision Simulator

    MedlinePlus

    ... Retina Treatment Retinal Detachment Vision Simulator Retinal Detachment Vision Simulator Mar. 01, 2016 How does a detached or torn retina affect your vision? If a retinal tear is occurring, you may ...

  20. [Novel mechanism for retinal vascular diseases].

    PubMed

    Suzuma, Kiyoshi

    2015-03-01

    I. A new therapeutic target for diabetic retinopathy. Recent reports state that succinate may be an independent retinal angiogenic factor. We evaluated concentrations in vitreous from proliferative diabetic retinopathy (PDR), and found that succinate increased significantly in PDR. Interestingly, levels of succinate from bevacizumab-pre-injected PDR were normal, suggesting that vascular endothelial growth factor (VEGF) had a positive feedback mechanism for succinate since succinate was previously reported to induce VEGF. II. A new understanding of central retinal vein occlusion (CRVO). We evaluated retinal blood flow velocity with laser speckle flowgraphy (LSFG) made in Japan, and found that cases in which both macular edema and retinal blood flow velocity improved after anti-VEGF therapy had better prognosis. In ischemic CRVO at final visit, mean retinal blood velocity was less than 50% of fellow eyes after 1st anti-VEGF therapy, suggesting that those cases might have poor prognosis. LSFG is useful for evaluation and decision in CRVO treatment. III. From exploration for mechanism in retinal vascular diseases to re-vascularization therapy. The standard treatment for retinal non-perfusion area is scatter laser photocoagulation, which is both invasive of the peripheral retina and may prove destructive. Re-vascularization is an ideal strategy for treatment of retinal non-perfusion area. To develop a new methods for re-vascularization in retinal non-perfusion area, we have designed experiments using a retina without vasculature differentiated from induced pluripotent stem(iPS) cells. PMID:25854111

  1. The structure of large-scale synchronized firing in primate retina

    PubMed Central

    Shlens, Jonathon; Field, Greg D.; Gauthier, Jeffrey L.; Greschner, Martin; Sher, Alexander; Litke, Alan M.; Chichilnisky, E.J.

    2009-01-01

    Synchronized firing among neurons has been proposed to constitute an elementary aspect of the neural code in sensory and motor systems. However, it remains unclear how synchronized firing affects the large-scale patterns of activity and redundancy of visual signals in a complete population of neurons. We recorded simultaneously from hundreds of retinal ganglion cells in primate retina, and examined synchronized firing in completely sampled populations of ~50–100 ON-parasol cells, which form a major projection to the magnocellular layers of the lateral geniculate nucleus. Synchronized firing in pairs of cells was a subset of a much larger pattern of activity that exhibited local, isotropic spatial properties. However, a simple model based solely on interactions between adjacent cells reproduced 99% of the spatial structure and scale of synchronized firing. No more than 20% of the variability in firing of an individual cell was predictable from the activity of its neighbors. These results held both for spontaneous firing and in the presence of independent visual modulation of the firing of each cell. In sum, large-scale synchronized firing in the entire population of ON-parasol cells appears to reflect simple neighbor interactions, rather than a unique visual signal or a highly redundant coding scheme. PMID:19369571

  2. Branch retinal vein occlusion.

    PubMed

    Hamid, Sadaf; Mirza, Sajid Ali; Shokh, Ishrat

    2008-01-01

    Retinal vein occlusions (RVO) are the second commonest sight threatening vascular disorder. Branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO) are the two basic types of vein occlusion. Branch retinal vein occlusion is three times more common than central retinal vein occlusion and- second only to diabetic retinopathy as the most common retinal vascular cause of visual loss. The origin of branch retinal vein occlusion undoubtedly includes both systemic factors such as hypertension and local anatomic factors such as arteriovenous crossings. Branch retinal vein occlusion causes a painless decrease in vision, resulting in misty or distorted vision. Current treatment options don't address the underlying aetiology of branch retinal vein occlusion. Instead they focus on treating sequelae of the occluded venous branch, such as macular oedema, vitreous haemorrhage and traction retinal detachment from neovascularization. Evidences suggest that the pathogenesis of various types of retinal vein occlusion, like many other ocular vascular occlusive disorders, is a multifactorial process and there is no single magic bullet that causes retinal vein occlusion. A comprehensive management of patients with retinal vascular occlusions is necessary to correct associated diseases or predisposing abnormalities that could lead to local recurrences or systemic event. Along with a review of the literature, a practical approach for the management of retinal vascular occlusions is required, which requires collaboration between the ophthalmologist and other physicians: general practitioner, cardiologist, internist etc. as appropriate according to each case. PMID:19385476

  3. Retinal Oscillations Carry Visual Information to Cortex

    PubMed Central

    Koepsell, Kilian; Wang, Xin; Vaingankar, Vishal; Wei, Yichun; Wang, Qingbo; Rathbun, Daniel L.; Usrey, W. Martin; Hirsch, Judith A.; Sommer, Friedrich T.

    2009-01-01

    Thalamic relay cells fire action potentials that transmit information from retina to cortex. The amount of information that spike trains encode is usually estimated from the precision of spike timing with respect to the stimulus. Sensory input, however, is only one factor that influences neural activity. For example, intrinsic dynamics, such as oscillations of networks of neurons, also modulate firing pattern. Here, we asked if retinal oscillations might help to convey information to neurons downstream. Specifically, we made whole-cell recordings from relay cells to reveal retinal inputs (EPSPs) and thalamic outputs (spikes) and then analyzed these events with information theory. Our results show that thalamic spike trains operate as two multiplexed channels. One channel, which occupies a low frequency band (<30 Hz), is encoded by average firing rate with respect to the stimulus and carries information about local changes in the visual field over time. The other operates in the gamma frequency band (40–80 Hz) and is encoded by spike timing relative to retinal oscillations. At times, the second channel conveyed even more information than the first. Because retinal oscillations involve extensive networks of ganglion cells, it is likely that the second channel transmits information about global features of the visual scene. PMID:19404487

  4. Independent Validation and Verification of Process Design and Optimization Technology Diagnostic and Control of Natural Gas Fired Furnaces via Flame Image Analysis Technology

    SciTech Connect

    Cox, Daryl

    2009-05-01

    The United States Department of Energy, Industrial Technologies Program has invested in emerging Process Design and Optimizations Technologies (PDOT) to encourage the development of new initiatives that might result in energy savings in industrial processes. Gas fired furnaces present a harsh environment, often making accurate determination of correct air/fuel ratios a challenge. Operation with the correct air/fuel ratio and especially with balanced burners in multi-burner combustion equipment can result in improved system efficiency, yielding lower operating costs and reduced emissions. Flame Image Analysis offers a way to improve individual burner performance by identifying and correcting fuel-rich burners. The anticipated benefit of this technology is improved furnace thermal efficiency, and lower NOx emissions. Independent validation and verification (V&V) testing of the FIA technology was performed at Missouri Forge, Inc., in Doniphan, Missouri by Environ International Corporation (V&V contractor) and Enterprise Energy and Research (EE&R), the developer of the technology. The test site was selected by the technology developer and accepted by Environ after a meeting held at Missouri Forge. As stated in the solicitation for the V&V contractor, 'The objective of this activity is to provide independent verification and validation of the performance of this new technology when demonstrated in industrial applications. A primary goal for the V&V process will be to independently evaluate if this technology, when demonstrated in an industrial application, can be utilized to save a significant amount of the operating energy cost. The Seller will also independently evaluate the other benefits of the demonstrated technology that were previously identified by the developer, including those related to product quality, productivity, environmental impact, etc'. A test plan was provided by the technology developer and is included as an appendix to the summary report submitted

  5. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.; Christenson, Todd R.

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  6. The Structure and Precision of Retinal Spike Trains

    NASA Astrophysics Data System (ADS)

    Berry, Michael J.; Warland, David K.; Meister, Markus

    1997-05-01

    Assessing the reliability of neuronal spike trains is fundamental to an understanding of the neural code. We measured the reproducibility of retinal responses to repeated visual stimuli. In both tiger salamander and rabbit, the retinal ganglion cells responded to random flicker with discrete, brief periods of firing. For any given cell, these firing events covered only a small fraction of the total stimulus time, often less than 5%. Firing events were very reproducible from trial to trial: the timing jitter of individual spikes was as low as 1 msec, and the standard deviation in spike count was often less than 0.5 spikes. Comparing the precision of spike timing to that of the spike count showed that the timing of a firing event conveyed several times more visual information than its spike count. This sparseness and precision were general characteristics of ganglion cell responses, maintained over the broad ensemble of stimulus waveforms produced by random flicker, and over a range of contrasts. Thus, the responses of retinal ganglion cells are not properly described by a firing probability that varies continuously with the stimulus. Instead, these neurons elicit discrete firing events that may be the fundamental coding symbols in retinal spike trains.

  7. Genetic pediatric retinal diseases

    PubMed Central

    Say, Emil Anthony T.

    2014-01-01

    Hereditary pediatric retinal diseases are a diverse group of disorders with pathologies affecting different cellular structures or retinal development. Many can mimic typical pediatric retinal disease such as retinopathy of prematurity, vitreous hemorrhage, retinal detachment and cystoid macular edema. Multisystem involvement is frequently seen in hereditary pediatric retinal disease. A thorough history coupled with a good physical examination can oftentimes lead the ophthalmologist or pediatrician to the correct genetic test and correct diagnosis. In some instances, evaluation of parents or siblings may be required to determine familial involvement when the history is inconclusive or insufficient and clinical suspicion is high.

  8. Concerted Signaling by Retinal Ganglion Cells

    NASA Astrophysics Data System (ADS)

    Meister, Markus; Lagnado, Leon; Baylor, Denis A.

    1995-11-01

    To analyze the rules that govern communication between eye and brain, visual responses were recorded from an intact salamander retina. Parallel observation of many retinal ganglion cells with a microelectrode array showed that nearby neurons often fired synchronously, with spike delays of less than 10 milliseconds. The frequency of such synchronous spikes exceeded the correlation expected from a shared visual stimulus up to 20-fold. Synchronous firing persisted under a variety of visual stimuli and accounted for the majority of action potentials recorded. Analysis of receptive fields showed that concerted spikes encoded information not carried by individual cells; they may represent symbols in a multineuronal code for vision.

  9. Genetics Home Reference: retinitis pigmentosa

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions retinitis pigmentosa retinitis pigmentosa Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Retinitis pigmentosa is a group of related eye disorders that ...

  10. The retinal ciliopathies.

    PubMed

    Adams, N A; Awadein, Ahmed; Toma, Hassanain S

    2007-09-01

    While the functions of many of the proteins located in or associated with the photoreceptor cilia are poorly understood, disruption of the function of these proteins may result in a wide variety of phenotypes ranging from isolated retinal degeneration to more pleiotropic phenotypes. Systemic findings include neurosensory hearing loss, developmental delay, situs-inversus, infertility, disorders of limb and digit development, obesity, kidney disease, liver disease, and respiratory disease. The concept of "retinal ciliopathies" brings to attention the importance of further molecular analysis of this organelle as well as provides a potential common target for therapies for these disorders. The retinal ciliopathies include retinitis pigmentosa, macular degeneration, cone-dystrophy, cone-rod dystrophy, Leber congenital amaurosis, as well as retinal degenerations associated with Usher syndrome, primary ciliary dyskinesia, Senior-Loken syndrome, Joubert syndrome, Bardet-Biedl syndrome, Laurence-Moon syndrome, McKusick-Kaufman syndrome, and Biemond syndrome. Mutations for these disorders have been found in retinitis pigmentosa-1 (RP1), retinitis pigmentosa GTPase regulator (RPGR), retinitis pigmentosa GTPase regulator interacting protein (RPGR-IP), as well as the Usher, Bardet-Biedl, and nephronophthisis genes. Other systemic disorders associated with retinal degenerations that may also involve ciliary abnormalities include: Alstrom, Edwards-Sethi, Ellis-van Creveld, Jeune, Meckel-Gruber, Orofaciodigital Type 9, and Gurrieri syndromes. Understanding these conditions as ciliopathies may help the ophthalmologist to recognize associations between seemingly unrelated diseases and have a high degree of suspicion that a systemic finding may be present. PMID:17896309

  11. Airborne forest fire research

    NASA Technical Reports Server (NTRS)

    Mattingly, G. S.

    1974-01-01

    The research relating to airborne fire fighting systems is reviewed to provide NASA/Langley Research Center with current information on the use of aircraft in forest fire operations, and to identify research requirements for future operations. A literature survey, interview of forest fire service personnel, analysis and synthesis of data from research reports and independent conclusions, and recommendations for future NASA-LRC programs are included.

  12. VANISHING RETINAL DETACHMENT

    PubMed Central

    2015-01-01

    Purpose: The purpose of this report is to describe a case of rhegmatogenous retinal detachment in the setting of chronic kidney disease that exhibited complete retinal reattachment after serial hemodialysis. Methods: Retrospective case report. Results: A 58-year-old woman with acute vision loss was found to have a macula-involving rhegmatogenous retinal detachment. Due to chronic kidney disease, she continued with routinely scheduled hemodialysis for 1 week until surgical clearance was obtained. Preoperative examination revealed complete reattachment of the retina with a persistent retinal tear. Barrier laser was applied to the tear and the retina remained attached until the most recent follow-up 8 months later. The workup of alternate etiologies was unrevealing. Conclusion: This case describes a temporal association between hemodialysis and resolution of subretinal fluid due to rhegmatogenous retinal detachment. A potential causal linkage is suggested based on shifting fluid dynamics associated with hemodialysis. A shift in treatment paradigm is not advised. PMID:26352323

  13. AAV Mediated GDNF Secretion From Retinal Glia Slows Down Retinal Degeneration in a Rat Model of Retinitis Pigmentosa

    PubMed Central

    Dalkara, Deniz; Kolstad, Kathleen D; Guerin, Karen I; Hoffmann, Natalie V; Visel, Meike; Klimczak, Ryan R; Schaffer, David V; Flannery, John G

    2011-01-01

    Mutations in over 80 identified genes can induce apoptosis in photoreceptors, resulting in blindness with a prevalence of 1 in 3,000 individuals. This broad genetic heterogeneity of disease impacting a wide range of photoreceptor functions renders the design of gene-specific therapies for photoreceptor degeneration impractical and necessitates the development of mutation-independent treatments to slow photoreceptor cell death. One promising strategy for photoreceptor neuroprotection is neurotrophin secretion from Müller cells, the primary retinal glia. Müller glia are excellent targets for secreting neurotrophins as they span the entire tissue, ensheath all neuronal populations, are numerous, and persist through retinal degeneration. We previously engineered an adeno-associated virus (AAV) variant (ShH10) capable of efficient and selective glial cell transduction through intravitreal injection. ShH10-mediated glial-derived neurotrophic factor (GDNF) secretion from glia, generates high GDNF levels in treated retinas, leading to sustained functional rescue for over 5 months. This GDNF secretion from glia following intravitreal vector administration is a safe and effective means to slow the progression of retinal degeneration in a rat model of retinitis pigmentosa (RP) and shows significant promise as a gene therapy to treat human retinal degenerations. These findings also demonstrate for the first time that glia-mediated secretion of neurotrophins is a promising treatment that may be applicable to other neurodegenerative conditions. PMID:21522134

  14. Temperature controlled retinal photocoagulation

    NASA Astrophysics Data System (ADS)

    Schlott, Kerstin; Koinzer, Stefan; Baade, Alexander; Birngruber, Reginald; Roider, Johann; Brinkmann, Ralf

    2013-06-01

    Retinal photocoagulation lacks objective dosage in clinical use, thus the commonly applied lesions are too deep and strong, associated with pain reception and the risk of visual field defects and induction of choroidal neovascularisations. Optoacoustics allows real-time non-invasive temperature measurement in the fundus during photocoagulation by applying short probe laser pulses additionally to the treatment radiation, which excite the emission of ultrasonic waves. Due to the temperature dependence of the Grüneisen parameter, the amplitudes of the ultrasonic waves can be used to derive the temperature of the absorbing tissue. By measuring the temperatures in real-time and automatically controlling the irradiation by feedback to the treatment laser, the strength of the lesions can be defined. Different characteristic functions for the time and temperature dependent lesion sizes were used as rating curves for the treatment laser, stopping the irradiation automatically after a desired lesion size is achieved. The automatically produced lesion sizes are widely independent of the adjusted treatment laser power and individual absorption. This study was performed on anaesthetized rabbits and is a step towards a clinical trial with automatically controlled photocoagulation.

  15. Retinal topography maps in R: New tools for the analysis and visualization of spatial retinal data

    PubMed Central

    Cohn, Brian A.; Collin, Shaun P.; Wainwright, Peter C.; Schmitz, Lars

    2015-01-01

    Retinal topography maps are a widely used tool in vision science, neuroscience, and visual ecology, providing an informative visualization of the spatial distribution of cell densities across the retinal hemisphere. Here, we introduce Retina, an R package for computational mapping, inspection of topographic model fits, and generation of average maps. Functions in Retina take cell count data obtained from retinal wholemounts using stereology software. Accurate visualizations and comparisons between different eyes have been difficult in the past, because of deformation and incisions of retinal wholemounts. We account for these issues by incorporation of the R package Retistruct, which results in a retrodeformation of the wholemount into a hemispherical shape, similar to the original eyecup. The maps are generated by thin plate splines, after the data were transformed into a two-dimensional space with an azimuthal equidistant plot projection. Retina users can compute retinal topography maps independent of stereology software choice and assess model fits with a variety of diagnostic plots. Functionality of Retina also includes species average maps, an essential feature for interspecific analyses. The Retina package will facilitate rigorous comparative studies in visual ecology by providing a robust quantitative approach to generate retinal topography maps. PMID:26230981

  16. Differential Diagnosis of Retinal Vasculitis

    PubMed Central

    Abu El-Asrar, Ahmed M.; Herbort, Carl P.; Tabbara, Khalid F.

    2009-01-01

    Retinal vaculitis is a sight-threatening inflammatory eye condition that involves the retinal vessels. Detection of retinal vasculitis is made clinically, and confirmed with the help of fundus fluorescein angiography. Active vascular disease is characterized by exudates around retinal vessels resulting in white sheathing or cuffing of the affected vessels. In this review, a practical approach to the diagnosis of retinal vasculitis is discussed based on ophthalmoscopic and fundus fluorescein angiographic findings. PMID:20404987

  17. 46 CFR 108.415 - Fire pump: General.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... EQUIPMENT Fire Extinguishing Systems Fire Main System § 108.415 Fire pump: General. A fire main system must have at least two independently driven fire pumps that can each deliver water at a continuous pitot... 46 Shipping 4 2014-10-01 2014-10-01 false Fire pump: General. 108.415 Section 108.415...

  18. 46 CFR 108.415 - Fire pump: General.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... EQUIPMENT Fire Extinguishing Systems Fire Main System § 108.415 Fire pump: General. A fire main system must have at least two independently driven fire pumps that can each deliver water at a continuous pitot... 46 Shipping 4 2010-10-01 2010-10-01 false Fire pump: General. 108.415 Section 108.415...

  19. 46 CFR 108.415 - Fire pump: General.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... EQUIPMENT Fire Extinguishing Systems Fire Main System § 108.415 Fire pump: General. A fire main system must have at least two independently driven fire pumps that can each deliver water at a continuous pitot... 46 Shipping 4 2011-10-01 2011-10-01 false Fire pump: General. 108.415 Section 108.415...

  20. 46 CFR 108.415 - Fire pump: General.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... EQUIPMENT Fire Extinguishing Systems Fire Main System § 108.415 Fire pump: General. A fire main system must have at least two independently driven fire pumps that can each deliver water at a continuous pitot... 46 Shipping 4 2013-10-01 2013-10-01 false Fire pump: General. 108.415 Section 108.415...

  1. 46 CFR 108.415 - Fire pump: General.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... EQUIPMENT Fire Extinguishing Systems Fire Main System § 108.415 Fire pump: General. A fire main system must have at least two independently driven fire pumps that can each deliver water at a continuous pitot... 46 Shipping 4 2012-10-01 2012-10-01 false Fire pump: General. 108.415 Section 108.415...

  2. Retinal vascular regeneration.

    PubMed

    Otani, Atsushi; Friedlander, Martin

    2005-01-01

    We discuss the potential use of stem cells for therapeutic angiogenesis in the treatment of retinal diseases. We demonstrate that the clinical utility of these EPC may be not limited in the treatment of ischemic retinal diseases but may also have application for the treatment of retinal degenerative disorders and for a form of cell-based gene therapy. One of the greatest potential benefits of bone marrow derived EPC therapy is the possible use of autologous grafts. Nonetheless, potential toxicities and unregulated cell growth will need to be carefully evaluated before this approach is brought to the clinics. PMID:15804843

  3. Retinal vein occlusion

    MedlinePlus

    ... Berrocal MH, Rodriguez FJ, et al. Pan-American Collaborative Retina Study Group (PACORES). Comparison of two doses ... retinal vein occlusion: results from the Pan-American Collaborative Retina Study Group at 6 months of follow- ...

  4. [Acute retinal necrosis].

    PubMed

    Lucke, K; Reinking, U; el-Hifnawi, E; Dennin, R H; Laqua, H

    1988-12-01

    The authors report on three patients with acute retinal necrosis who were treated with the virostatic agent Acyclovir and who underwent vitreoretinal surgery with silicone oil filling for total retinal detachment. In two eyes the retina was reattached, but useful vision was only preserved in one patient. Titers from blood and the vitreous, as well as microscopic findings in retinal biopsies, support the view that the necrosis is caused by a herpes simplex virus infection. After therapy with Acyclovir was instituted no further progression on the necrosis was observed. However, the development of retinal detachment could not be prevented. Early diagnosis and antiviral therapy are essential to improve the otherwise poor prognosis in this rare syndrome. PMID:3221657

  5. Retinal detachment in pseudophakia.

    PubMed

    Galin, M A; Poole, T A; Obstbaum, S A

    1979-07-01

    In a series of cataract patients excluding myopic individuals, under age 60 years, and cases in which vitreous loss occurred, retinal detachment was no less frequent after intracapsular cataract extraction and Sputnik iris supported lenses than in controls. Both groups were followed up for a minimum of two years. The detachments predominantly occurred from retinal breaks in areas of the retina that looked normal preoperatively. PMID:464014

  6. Giant retinal tears.

    PubMed

    Shunmugam, Manoharan; Ang, Ghee Soon; Lois, Noemi

    2014-01-01

    A giant retinal tear (GRT) is a full-thickness neurosensory retinal break that extends circumferentially around the retina for three or more clock hours in the presence of a posteriorly detached vitreous. Its incidence in large population-based studies has been estimated as 1.5% of rhegmatogenous retinal detachments, with a significant male preponderance, and bilaterality in 12.8%. Most GRTs are idiopathic, with trauma, hereditary vitreoretinopathies and high myopia each being causative in decreasing frequency. The vast majority of GRTs are currently managed with a pars plana vitrectomy; the use of adjunctive circumferential scleral buckling is debated, but no studies have shown a clear anatomical or visual advantage with its use. Similarly, silicone oil tamponade does not influence long-term outcomes when compared with gas. Primary and final retinal reattachment rates are achieved in 88% and 95% of patients, respectively. Even when the retina remains attached, however, visual recovery may be limited. Furthermore, fellow eyes of patients with a GRT are at higher risk of developing retinal tears and retinal detachment. Prophylactic treatment under these circumstances may be considered but there is no firm evidence of its efficacy at the present time. PMID:24138895

  7. Progressive outer retinal necrosis-like retinitis in immunocompetent hosts.

    PubMed

    Chawla, Rohan; Tripathy, Koushik; Gogia, Varun; Venkatesh, Pradeep

    2016-01-01

    We describe two young immunocompetent women presenting with bilateral retinitis with outer retinal necrosis involving posterior pole with centrifugal spread and multifocal lesions simulating progressive outer retinal necrosis (PORN) like retinitis. Serology was negative for HIV and CD4 counts were normal; however, both women were on oral steroids at presentation for suspected autoimmune chorioretinitis. The retinitis in both eyes responded well to oral valaciclovir therapy. However, the eye with the more fulminant involvement developed retinal detachment with a loss of vision. Retinal atrophy was seen in the less involved eye with preservation of vision. Through these cases, we aim to describe a unique evolution of PORN-like retinitis in immunocompetent women, which was probably aggravated by a short-term immunosuppression secondary to oral steroids. PMID:27511757

  8. Bacterioopsin-triggered retinal biosynthesis is inhibited by bacteriorhodopsin formation in Halobacterium salinarium.

    PubMed

    Deshpande, A; Sonar, S

    1999-08-13

    Factors regulating retinal biosynthesis in halobacteria are not clearly understood. In halobacteria, events leading to the biosynthesis of bacteriorhodopsin have been proposed to participate in stringent regulation of retinal biosynthesis. The present study describes a novel approach of in vivo introductions of mRNA and membrane proteins via liposome fusion to test their role in cellular metabolism. Both the bacterioopsin-encoding mRNA and the liposome-encapsulated bacterioopsin (apoprotein) are independently introduced in spheroplasts of the purple membrane-negative strain Halobacterium salinarium that initially contain neither bacterioopsin nor retinal. Isoprenoid analyses of these cells indicate that the expression/presence of bacterioopsin triggers retinal biosynthesis from lycopene, and its subsequent binding to opsin generates bacteriorhodopsin. When bacteriorhodopsin and excess retinal were independently introduced into spheroplasts of purple membrane-negative cells, the introduction of bacteriorhodopsin resulted in an accumulation of lycopene, indicating an inhibition of retinal biosynthesis. These results provide direct evidence that the formation of bacterioopsin acts as a trigger for lycopene conversion to beta-carotene in retinal biosynthesis. The trigger for this event does not lie with either transcription or translation of the bop gene. It is clearly associated with the folded and the membrane-integrated state of bacterioopsin. On the other hand, the trigger signaling inhibition of retinal biosynthesis does not lie with the presence of excess retinal but with the correctly folded, retinal-bound form, bacteriorhodopsin. PMID:10438533

  9. Photovoltaic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Loudin, James; Mathieson, Keith; Kamins, Ted; Wang, Lele; Galambos, Ludwig; Huie, Philip; Sher, Alexander; Harris, James; Palanker, Daniel

    2011-03-01

    Electronic retinal prostheses seek to restore sight to patients suffering from retinal degenerative disorders. Implanted electrode arrays apply patterned electrical stimulation to surviving retinal neurons, producing visual sensations. All current designs employ inductively coupled coils to transmit power and/or data to the implant. We present here the design and initial testing of a photovoltaic retinal prosthesis fabricated with a pixel density of up to 177 pixels/mm2. Photodiodes within each pixel of the subretinal array directly convert light to stimulation current, avoiding the use of bulky coil implants, decoding electronics, and wiring, and thereby reducing surgical complexity. A goggles-mounted camera captures the visual scene and transmits the data stream to a pocket processor. The resulting images are projected into the eyes by video goggles using pulsed, near infrared (~900 nm) light. Prostheses with three pixel densities (15, 55, and 177 pix/mm2) are being fabricated, and tests indicate a charge injection limit of 1.62 mC/cm2 at 25Hz. In vitro tests of the photovoltaic retinal stimulation using a 512-element microelectrode array have recorded stimulated spikes from the ganglion cells, with latencies in the 1-100ms range, and with peak irradiance stimulation thresholds varying from 0.1 to 1 mW/mm2. With 1ms pulses at 25Hz the average irradiance is more than 100 times below the IR retinal safety limit. Elicited retinal response disappeared upon the addition of synaptic blockers, indicating that the inner retina is stimulated rather than the ganglion cells directly, and raising hopes that the prosthesis will preserve some of the retina's natural signal processing.

  10. Peripheral retinal non-perfusion and treatment response in branch retinal vein occlusion

    PubMed Central

    Abri Aghdam, Kaveh; Reznicek, Lukas; Soltan Sanjari, Mostafa; Framme, Carsten; Bajor, Anna; Klingenstein, Annemarie; Kernt, Marcus; Seidensticker, Florian

    2016-01-01

    AIM To evaluate the association between the size of peripheral retinal non-perfusion and the number of intravitreal ranibizumab injections in patients with treatment-naive branch retinal vein occlusion (BRVO) and macular edema. METHODS A total of 53 patients with treatment-naive BRVO and macular edema were included. Each patient underwent a full ophthalmologic examination including optical coherence tomography (OCT) imaging and ultra wide-field fluorescein angiography (UWFA). Monthly intravitreal ranibizumab injections were applied according to the recommendations of the German Ophthalmological Society. Two independent, masked graders quantified the areas of peripheral retinal non-perfusion. RESULTS Intravitreal injections improved best-corrected visual acuity (BCVA) significantly from 22.23±16.33 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters to 36.23±15.19 letters (P<0.001), and mean central subfield thickness significantly reduced from 387±115 µm to 321±115 µm (P=0.01). Mean number of intravitreal ranibizumab injections was 3.61±1.56. The size of retinal non-perfusion correlated significantly with the number of intravitreal ranibizumab injections (R=0.724, P<0.001). CONCLUSION Peripheral retinal non-perfusion in patients with BRVO associates significantly with intravitreal ranibizumab injections in patients with BRVO and macular edema. PMID:27366688

  11. Retinal Adaptation to Object Motion

    PubMed Central

    Ölveczky, Bence P.; Baccus, Stephen A.; Meister, Markus

    2007-01-01

    Summary Due to fixational eye movements, the image on the retina is always in motion, even when one views a stationary scene. When an object moves within the scene, the corresponding patch of retina experiences a different motion trajectory than the surrounding region. Certain retinal ganglion cells respond selectively to this condition, when the motion in the cell’s receptive field center is different from that in the surround. Here we show that this response is strongest at the very onset of differential motion, followed by gradual adaptation with a time course of several seconds. Different subregions of a ganglion cell’s receptive field can adapt independently. The circuitry responsible for differential motion adaptation lies in the inner retina. Several candidate mechanisms were tested, and the adaptation most likely results from synaptic depression at the synapse from bipolar to ganglion cell. Similar circuit mechanisms may act more generally to emphasize novel features of a visual stimulus. PMID:18031685

  12. Probabilistic retinal vessel segmentation

    NASA Astrophysics Data System (ADS)

    Wu, Chang-Hua; Agam, Gady

    2007-03-01

    Optic fundus assessment is widely used for diagnosing vascular and non-vascular pathology. Inspection of the retinal vasculature may reveal hypertension, diabetes, arteriosclerosis, cardiovascular disease and stroke. Due to various imaging conditions retinal images may be degraded. Consequently, the enhancement of such images and vessels in them is an important task with direct clinical applications. We propose a novel technique for vessel enhancement in retinal images that is capable of enhancing vessel junctions in addition to linear vessel segments. This is an extension of vessel filters we have previously developed for vessel enhancement in thoracic CT scans. The proposed approach is based on probabilistic models which can discern vessels and junctions. Evaluation shows the proposed filter is better than several known techniques and is comparable to the state of the art when evaluated on a standard dataset. A ridge-based vessel tracking process is applied on the enhanced image to demonstrate the effectiveness of the enhancement filter.

  13. Retinal lesions in septicemia.

    PubMed

    Neudorfer, M; Barnea, Y; Geyer, O; Siegman-Igra, Y

    1993-12-15

    We explored the association between septicemia and specific retinal lesions in a prospective controlled study. Hemorrhages, cotton-wool spots, or Roth's spots were found in 24 of 101 septicemic patients (24%), compared to four of 99 age- and gender-matched control patients (4%) (P = .0002). There was no significant association between types of organisms or focus of infection and the presence of specific lesions. Histologic examination of affected eyes disclosed cytoid bodies in the nerve fiber layer without inflammation. A definite association between septicemia and retinal lesions was found and indicates the need for routine ophthalmoscopy in septicemic patients. PMID:8250076

  14. Pathway to Retinal Oximetry

    PubMed Central

    Beach, James

    2014-01-01

    Events and discoveries in oxygen monitoring over the past two centuries are presented as the background from which oximetry of the human retina evolved. Achievements and the people behind them are discussed, showing parallels between the work in tissue measurements and later in the eye. Developments in the two-wavelength technique for oxygen saturation measurements in retinal vessels are shown to exploit the forms of imaging technology available over time. The last section provides a short summary of the recent research in retinal diseases using vessel oximetry. PMID:25237591

  15. A precisely timed asynchronous pattern of ON and OFF retinal ganglion cell activity during propagation of retinal waves

    PubMed Central

    Kerschensteiner, Daniel; Wong, Rachel O.L.

    2008-01-01

    Summary Patterns of coordinated spontaneous activity have been proposed to guide circuit refinement in many parts of the developing nervous system. It is unclear, however, how such patterns, which are thought to indiscriminately synchronize nearby cells, could provide the cues necessary to segregate functionally distinct circuits within overlapping cell populations. Here we report that glutamatergic retinal waves possess a novel substructure in the bursting of neighboring retinal ganglion cells with opposite light responses (ON or OFF). Within a wave, cells fire repetitive non-overlapping bursts in a fixed order: ON before OFF. This pattern is absent from cholinergic waves, which precede glutamate-dependent activity, providing a developmental sequence of distinct activity-encoded cues. Asynchronous bursting of ON and OFF retinal ganglion cells depends on inhibition between these parallel pathways. Similar asynchronous activity patterns could arise throughout the nervous system as inhibition matures and might help to separate connections of functionally distinct subnetworks. PMID:18579076

  16. 46 CFR 76.10-5 - Fire pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Fire pumps. 76.10-5 Section 76.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 76.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven fire pumps...

  17. Live imaging and analysis of postnatal mouse retinal development

    PubMed Central

    2013-01-01

    Background The explanted, developing rodent retina provides an efficient and accessible preparation for use in gene transfer and pharmacological experimentation. Many of the features of normal development are retained in the explanted retina, including retinal progenitor cell proliferation, heterochronic cell production, interkinetic nuclear migration, and connectivity. To date, live imaging in the developing retina has been reported in non-mammalian and mammalian whole-mount samples. An integrated approach to rodent retinal culture/transfection, live imaging, cell tracking, and analysis in structurally intact explants greatly improves our ability to assess the kinetics of cell production. Results In this report, we describe the assembly and maintenance of an in vitro, CO2-independent, live mouse retinal preparation that is accessible by both upright and inverted, 2-photon or confocal microscopes. The optics of this preparation permit high-quality and multi-channel imaging of retinal cells expressing fluorescent reporters for up to 48h. Tracking of interkinetic nuclear migration within individual cells, and changes in retinal progenitor cell morphology are described. Follow-up, hierarchical cluster screening revealed that several different dependent variable measures can be used to identify and group movement kinetics in experimental and control samples. Conclusions Collectively, these methods provide a robust approach to assay multiple features of rodent retinal development using live imaging. PMID:23758927

  18. Retinal Vascular Caliber and Brachial Flow-Mediated Dilation

    PubMed Central

    Nguyen, Thanh T.; Islam, F.M. Amirul; Farouque, H.M. Omar; Klein, Ronald; Klein, Barbara E.K.; Cotch, Mary Frances; Herrington, David M.; Wong, Tien Yin

    2010-01-01

    Background and Purpose Retinal vascular caliber changes have been shown to predict stroke, but the underlying mechanism of this association is unknown. We examined the relationship between retinal vascular caliber with brachial flow-mediated dilation (FMD), a measure of systemic endothelial function. Methods The Multi-Ethnic Study of Atherosclerosis (MESA) is a population-based study of persons 45 to 84 years of age residing in 6 US communities free of clinical cardiovascular disease at baseline. Brachial FMD data were collected at baseline (July 2000 to June 2002), and retinal vascular caliber was measured from digital retinal photographs at the second examination, immediately after the first (August 2002 to January 2004). Data were available for 2851 participants for analysis. Results The mean brachial FMD was 4.39±2.79%. After adjusting for age and gender, brachial FMD was reduced in persons with wider retinal venular caliber (changes in FMD −0.25, 95% CI, −0.36, − 0.13; P<0.001, per SD increase in venular caliber). This relationship persists after adjusting for systolic blood pressure, serum total cholesterol, use of lipid-lowering and antihypertensive medication, body mass index, current smoking status, and hemoglobinA1C (−0.18; 95% CI −0.30, − 0.06; P=0.004, per SD increase in venular caliber). Brachial FMD was not associated with retinal arteriolar caliber. Conclusions Persons with wider retinal venules have reduced brachial FMD, independent of other vascular risk factors. This suggests that retinal venular caliber, previously shown to predict stroke, may be a marker of underlying systemic endothelial dysfunction. PMID:20508189

  19. Retinal Detachment: Torn or Detached Retina Diagnosis

    MedlinePlus

    ... Eye Health / Eye Health A-Z Detached or Torn Retina Sections Retinal Detachment: What Is a Torn ... Retina Treatment Retinal Detachment Vision Simulator Retinal Detachment: Torn or Detached Retina Diagnosis Written by: Kierstan Boyd ...

  20. Retinal Detachment: Torn or Detached Retina Symptoms

    MedlinePlus

    ... Eye Health / Eye Health A-Z Detached or Torn Retina Sections Retinal Detachment: What Is a Torn ... Retina Treatment Retinal Detachment Vision Simulator Retinal Detachment: Torn or Detached Retina Symptoms Written by: Kierstan Boyd ...

  1. Understory Fires

    NASA Video Gallery

    The flames of understory fires in the southern Amazon reach on average only a few feet tall, but the fire type can claim anywhere from 10 to 50 percent of a burn area's trees. Credit: NASA/Doug Morton

  2. Texas Fires

    Atmospheric Science Data Center

    2014-05-15

    article title:  Wind-Whipped Fires in East Texas     View Larger Image ... western side of the storm stoked fires throughout eastern Texas, which was already suffering from the worst one-year drought on record ...

  3. Small Animal Retinal Imaging

    NASA Astrophysics Data System (ADS)

    Choi, WooJhon; Drexler, Wolfgang; Fujimoto, James G.

    Developing and validating new techniques and methods for small animal imaging is an important research area because there are many small animal models of retinal diseases such as diabetic retinopathy, age-related macular degeneration, and glaucoma [1-6]. Because the retina is a multilayered structure with distinct abnormalities occurring in different intraretinal layers at different stages of disease progression, there is a need for imaging techniques that enable visualization of these layers individually at different time points. Although postmortem histology and ultrastructural analysis can be performed for investigating microscopic changes in the retina in small animal models, this requires sacrificing animals, which makes repeated assessment of the same animal at different time points impossible and increases the number of animals required. Furthermore, some retinal processes such as neurovascular coupling cannot be fully characterized postmortem.

  4. Inherited Retinal Degenerative Disease Registry

    ClinicalTrials.gov

    2016-03-21

    Eye Diseases Hereditary; Retinal Disease; Achromatopsia; Bardet-Biedl Syndrome; Bassen-Kornzweig Syndrome; Batten Disease; Best Disease; Choroidal Dystrophy; Choroideremia; Cone Dystrophy; Cone-Rod Dystrophy; Congenital Stationary Night Blindness; Enhanced S-Cone Syndrome; Fundus Albipunctatus; Goldmann-Favre Syndrome; Gyrate Atrophy; Juvenile Macular Degeneration; Kearns-Sayre Syndrome; Leber Congenital Amaurosis; Refsum Syndrome; Retinitis Pigmentosa; Retinitis Punctata Albescens; Retinoschisis; Rod-Cone Dystrophy; Rod Dystrophy; Rod Monochromacy; Stargardt Disease; Usher Syndrome

  5. [News in Retinal Imaging].

    PubMed

    Werkmeister, R; Schmidl, D; Garhöfer, G; Schmetterer, L

    2015-09-01

    New developments in retinal imaging have revolutionised ophthalmology in recent years. In particular, optical coherence tomography (OCT) provides highly resolved and well reproducible images and has rung in a new era in ophthalmological imaging. The technology was introduced in the early 1990 s, and has rapidly developed. There have been improvements in resolution, sensitivity and processing speed. There have also been developments in functional processing. OCT angiography is the first application in routine clinical work. PMID:26372783

  6. Glutamatergic Retinal Waves

    PubMed Central

    Kerschensteiner, Daniel

    2016-01-01

    Spontaneous activity patterns propagate through many parts of the developing nervous system and shape the wiring of emerging circuits. Prior to vision, waves of activity originating in the retina propagate through the lateral geniculate nucleus (LGN) of the thalamus to primary visual cortex (V1). Retinal waves have been shown to instruct the wiring of ganglion cell axons in LGN and of thalamocortical axons in V1 via correlation-based plasticity rules. Across species, retinal waves mature in three stereotypic stages (I–III), in which distinct circuit mechanisms give rise to unique activity patterns that serve specific functions in visual system refinement. Here, I review insights into the patterns, mechanisms, and functions of stage III retinal waves, which rely on glutamatergic signaling. As glutamatergic waves spread across the retina, neighboring ganglion cells with opposite light responses (ON vs. OFF) are activated sequentially. Recent studies identified lateral excitatory networks in the inner retina that generate and propagate glutamatergic waves, and vertical inhibitory networks that desynchronize the activity of ON and OFF cells in the wavefront. Stage III wave activity patterns may help segregate axons of ON and OFF ganglion cells in the LGN, and could contribute to the emergence of orientation selectivity in V1. PMID:27242446

  7. Fire Detector

    NASA Technical Reports Server (NTRS)

    1978-01-01

    An early warning fire detection sensor developed for NASA's Space Shuttle Orbiter is being evaluated as a possible hazard prevention system for mining operations. The incipient Fire Detector represents an advancement over commercially available smoke detectors in that it senses and signals the presence of a fire condition before the appearance of flame and smoke, offering an extra margin of safety.

  8. Retinal Thickening and Photoreceptor Loss in HIV Eyes without Retinitis

    PubMed Central

    Arcinue, Cheryl A.; Bartsch, Dirk-Uwe; El-Emam, Sharif Y.; Ma, Feiyan; Doede, Aubrey; Sharpsten, Lucie; Gomez, Maria Laura; Freeman, William R.

    2015-01-01

    Purpose To determine the presence of structural changes in HIV retinae (i.e., photoreceptor density and retinal thickness in the macula) compared with age-matched HIV-negative controls. Methods Cohort of patients with known HIV under CART (combination Antiretroviral Therapy) treatment were examined with a flood-illuminated retinal AO camera to assess the cone photoreceptor mosaic and spectral-domain optical coherence tomography (SD-OCT) to assess retinal layers and retinal thickness. Results Twenty-four eyes of 12 patients (n = 6 HIV-positive and 6 HIV-negative) were imaged with the adaptive optics camera. In each of the regions of interest studied (nasal, temporal, superior, inferior), the HIV group had significantly less mean cone photoreceptor density compared with age-matched controls (difference range, 4,308–6,872 cones/mm2). A different subset of forty eyes of 20 patients (n = 10 HIV-positive and 10 HIV-negative) was included in the retinal thickness measurements and retinal layer segmentation with the SD-OCT. We observed significant thickening in HIV positive eyes in the total retinal thickness at the foveal center, and in each of the three horizontal B-scans (through the macular center, superior, and inferior to the fovea). We also noted that the inner retina (combined thickness from ILM through RNFL to GCL layer) was also significantly thickened in all the different locations scanned compared with HIV-negative controls. Conclusion Our present study shows that the cone photoreceptor density is significantly reduced in HIV retinae compared with age-matched controls. HIV retinae also have increased macular retinal thickness that may be caused by inner retinal edema secondary to retinovascular disease in HIV. The interaction of photoreceptors with the aging RPE, as well as possible low-grade ocular inflammation causing diffuse inner retinal edema, may be the key to the progressive vision changes in HIV-positive patients without overt retinitis. PMID:26244973

  9. [Application of retinal oximeter in ophthalmology].

    PubMed

    Li, Jing; Ma, Jianmin; Wang, Ningli

    2015-11-01

    Retinal oximeter is a new machine which has been used in the diagnose, treatment and research of several ophthalmic diseases for recent years. It allows ophthalmologists to gain retinal oxygen saturation directly. Therefore, retinal oximeter might be useful for ophthalmologists to understand ophthalmic diseases more deeper and clarify the impact of ischemia on retinal function. It has been reported in the literatures that retinal oximeter has potentially useful diagnostic and therapeutic indications in various eye diseases such as diabetic retinopathy, central retinal vein and artery occlusion, retinitis pigmentosa, glaucomatous optic neuropathy, et al. In this thesis, the application of retinal oximeter in ophthalmology is reviewed. PMID:26850588

  10. Retinal image quality assessment using generic features

    NASA Astrophysics Data System (ADS)

    Fasih, Mahnaz; Langlois, J. M. Pierre; Ben Tahar, Houssem; Cheriet, Farida

    2014-03-01

    Retinal image quality assessment is an important step in automated eye disease diagnosis. Diagnosis accuracy is highly dependent on the quality of retinal images, because poor image quality might prevent the observation of significant eye features and disease manifestations. A robust algorithm is therefore required in order to evaluate the quality of images in a large database. We developed an algorithm for retinal image quality assessment based on generic features that is independent from segmentation methods. It exploits the local sharpness and texture features by applying the cumulative probability of blur detection metric and run-length encoding algorithm, respectively. The quality features are combined to evaluate the image's suitability for diagnosis purposes. Based on the recommendations of medical experts and our experience, we compared a global and a local approach. A support vector machine with radial basis functions was used as a nonlinear classifier in order to classify images to gradable and ungradable groups. We applied our methodology to 65 images of size 2592×1944 pixels that had been graded by a medical expert. The expert evaluated 38 images as gradable and 27 as ungradable. The results indicate very good agreement between the proposed algorithm's predictions and the medical expert's judgment: the sensitivity and specificity for the local approach are respectively 92% and 94%. The algorithm demonstrates sufficient robustness to identify relevant images for automated diagnosis.

  11. Optimal retinal cyst segmentation from OCT images

    NASA Astrophysics Data System (ADS)

    Oguz, Ipek; Zhang, Li; Abramoff, Michael D.; Sonka, Milan

    2016-03-01

    Accurate and reproducible segmentation of cysts and fluid-filled regions from retinal OCT images is an important step allowing quantification of the disease status, longitudinal disease progression, and response to therapy in wet-pathology retinal diseases. However, segmentation of fluid-filled regions from OCT images is a challenging task due to their inhomogeneous appearance, the unpredictability of their number, size and location, as well as the intensity profile similarity between such regions and certain healthy tissue types. While machine learning techniques can be beneficial for this task, they require large training datasets and are often over-fitted to the appearance models of specific scanner vendors. We propose a knowledge-based approach that leverages a carefully designed cost function and graph-based segmentation techniques to provide a vendor-independent solution to this problem. We illustrate the results of this approach on two publicly available datasets with a variety of scanner vendors and retinal disease status. Compared to a previous machine-learning based approach, the volume similarity error was dramatically reduced from 81:3+/-56:4% to 22:2+/-21:3% (paired t-test, p << 0:001).

  12. Retinal Failure in Diabetes: a Feature of Retinal Sensory Neuropathy.

    PubMed

    Gray, Ellyn J; Gardner, Thomas W

    2015-12-01

    Physiologic adaptations mediate normal responses to short-term and long-term stresses to ensure organ function. Organ failure results if adaptive responses fail to resolve persistent stresses or maladaptive reactions develop. The retinal neurovascular unit likewise undergoes adaptive responses to diabetes resulting in a retinal sensory neuropathy analogous to other sensory neuropathies. Vision-threatening diabetic retinal neuropathy results from unremitting metabolic and inflammatory stresses, leading to macular edema and proliferative diabetic retinopathy, states of "retinal failure." Current regulatory strategies focus primarily on the retinal failure stages, but new diagnostic modalities and understanding of the pathophysiology of diabetic retinopathy may facilitate earlier treatment to maintain vision in persons with diabetes. PMID:26458378

  13. Intersecting Circuits Generate Precisely Patterned Retinal Waves

    PubMed Central

    Akrouh, Alejandro; Kerschensteiner, Daniel

    2013-01-01

    SUMMARY The developing retina generates spontaneous glutamatergic (stage III) waves of activity that sequentially recruit neighboring ganglion cells with opposite light responses (ON and OFF RGCs). This activity pattern is thought to help establish parallel ON and OFF pathways in downstream visual areas. The circuits that produce stage III waves and desynchronize ON and OFF RGC firing remain obscure. Using dual patch clamp recordings, we find that ON and OFF RGCs receive sequential excitatory input from ON and OFF cone bipolar cells (CBCs), respectively. This input sequence is generated by crossover circuits, in which ON CBCs control glutamate release from OFF CBCs via diffusely stratified inhibitory amacrine cells. In addition, neighboring ON CBCs communicate directly and indirectly through lateral glutamatergic transmission and gap junctions, both of which are required for wave initiation and propagation. Thus, intersecting lateral excitatory and vertical inhibitory circuits give rise to precisely patterned stage III retinal waves. PMID:23830830

  14. Perceptual Fading without Retinal Adaptation

    ERIC Educational Resources Information Center

    Hsieh, Po-Jang; Colas, Jaron T.

    2012-01-01

    A retinally stabilized object readily undergoes perceptual fading and disappears from consciousness. This startling phenomenon is commonly believed to arise from local bottom-up sensory adaptation to edge information that occurs early in the visual pathway, such as in the lateral geniculate nucleus of the thalamus or retinal ganglion cells. Here…

  15. Retinal Imaging and Image Analysis

    PubMed Central

    Abràmoff, Michael D.; Garvin, Mona K.; Sonka, Milan

    2011-01-01

    Many important eye diseases as well as systemic diseases manifest themselves in the retina. While a number of other anatomical structures contribute to the process of vision, this review focuses on retinal imaging and image analysis. Following a brief overview of the most prevalent causes of blindness in the industrialized world that includes age-related macular degeneration, diabetic retinopathy, and glaucoma, the review is devoted to retinal imaging and image analysis methods and their clinical implications. Methods for 2-D fundus imaging and techniques for 3-D optical coherence tomography (OCT) imaging are reviewed. Special attention is given to quantitative techniques for analysis of fundus photographs with a focus on clinically relevant assessment of retinal vasculature, identification of retinal lesions, assessment of optic nerve head (ONH) shape, building retinal atlases, and to automated methods for population screening for retinal diseases. A separate section is devoted to 3-D analysis of OCT images, describing methods for segmentation and analysis of retinal layers, retinal vasculature, and 2-D/3-D detection of symptomatic exudate-associated derangements, as well as to OCT-based analysis of ONH morphology and shape. Throughout the paper, aspects of image acquisition, image analysis, and clinical relevance are treated together considering their mutually interlinked relationships. PMID:21743764

  16. Quantitative analysis of retinal OCT.

    PubMed

    Sonka, Milan; Abràmoff, Michael D

    2016-10-01

    Clinical acceptance of 3-D OCT retinal imaging brought rapid development of quantitative 3-D analysis of retinal layers, vasculature, retinal lesions as well as facilitated new research in retinal diseases. One of the cornerstones of many such analyses is segmentation and thickness quantification of retinal layers and the choroid, with an inherently 3-D simultaneous multi-layer LOGISMOS (Layered Optimal Graph Image Segmentation for Multiple Objects and Surfaces) segmentation approach being extremely well suited for the task. Once retinal layers are segmented, regional thickness, brightness, or texture-based indices of individual layers can be easily determined and thus contribute to our understanding of retinal or optic nerve head (ONH) disease processes and can be employed for determination of disease status, treatment responses, visual function, etc. Out of many applications, examples provided in this paper focus on image-guided therapy and outcome prediction in age-related macular degeneration and on assessing visual function from retinal layer structure in glaucoma. PMID:27503080

  17. [Intrinsically Photosensitive Retinal Ganglion Cells].

    PubMed

    Skorkovská, K; Skorkovská, Š

    2015-06-01

    Recently discovered intrinsically photosensitive melanopsin-containing retinal ganglion cells contribute to circadian photoentrainment and pupillary constriction; recent works have also brought new evidence for their accessory role in the visual system in humans. Pupil light reaction driven by individual photoreceptors can be isolated by means of the so called chromatic pupillography. The use of chromatic stimuli to elicit different pupillary responses may become an objective clinical pupil test in the detection of retinal diseases and in assessing new therapeutic approaches particularly in hereditary retinal degenerations like retinitis pigmentosa. In advanced stages of disease, the pupil light reaction is even more sensitive than standard electroretinography for detecting residual levels of photoreceptor activity. This review summarizes current knowledge on intrinsically photosensitive retinal cells and highlights its possible implications for clinical practice. PMID:26201360

  18. Retinal connectivity and primate vision

    PubMed Central

    Lee, Barry B.; Martin, Paul R.; Grünert, Ulrike

    2012-01-01

    The general principles of retinal organization are now well known. It may seem surprising that retinal organization in the primate, which has a complex visual behavioral repertoire, appears relatively simple. In this review, we primarily consider retinal structure and function in primate species. Photoreceptor distribution and connectivity are considered as are connectivity in the outer and inner retina. One key issue is the specificity of retinal connections; we suggest that the retina shows connectional specificity but this is seldom complete, and we consider here the functional consequences of imprecise wiring. Finally, we consider how retinal systems can be linked to psychophysical descriptions of different channels, chromatic and luminance, which are proposed to exist in the primate visual system. PMID:20826226

  19. Retinal connectivity and primate vision.

    PubMed

    Lee, Barry B; Martin, Paul R; Grünert, Ulrike

    2010-11-01

    The general principles of retinal organization are now well known. It may seem surprising that retinal organization in the primate, which has a complex visual behavioral repertoire, appears relatively simple. In this review, we primarily consider retinal structure and function in primate species. Photoreceptor distribution and connectivity are considered as are connectivity in the outer and inner retina. One key issue is the specificity of retinal connections; we suggest that the retina shows connectional specificity but this is seldom complete, and we consider here the functional consequences of imprecise wiring. Finally, we consider how retinal systems can be linked to psychophysical descriptions of different channels, chromatic and luminance, which are proposed to exist in the primate visual system. PMID:20826226

  20. [Multifocal Vitelliform Retinal Lesion].

    PubMed

    Streicher, T; Špirková, J; Ilavská, M

    2015-06-01

    The authors present retrospective follow up of patient with bilateral multifocal vitelliform retinal lesion during the 18 years period. At this time, spontaneous improvement of objective picture on retina and subjective visual troubles was observed. It is probable, that this case is a part of the same symptom complex as a variant of Best´s hereditary disease. This conclusion was based on initial stadium of phenotypical expressivity and additional evaluations. The course and outcomes of visual functions were different. The hereditary transmission was not confirmed. PMID:26201364

  1. Intrinsically photosensitive retinal ganglion cells.

    PubMed

    Do, Michael Tri Hoang; Yau, King-Wai

    2010-10-01

    Life on earth is subject to alternating cycles of day and night imposed by the rotation of the earth. Consequently, living things have evolved photodetective systems to synchronize their physiology and behavior with the external light-dark cycle. This form of photodetection is unlike the familiar "image vision," in that the basic information is light or darkness over time, independent of spatial patterns. "Nonimage" vision is probably far more ancient than image vision and is widespread in living species. For mammals, it has long been assumed that the photoreceptors for nonimage vision are also the textbook rods and cones. However, recent years have witnessed the discovery of a small population of retinal ganglion cells in the mammalian eye that express a unique visual pigment called melanopsin. These ganglion cells are intrinsically photosensitive and drive a variety of nonimage visual functions. In addition to being photoreceptors themselves, they also constitute the major conduit for rod and cone signals to the brain for nonimage visual functions such as circadian photoentrainment and the pupillary light reflex. Here we review what is known about these novel mammalian photoreceptors. PMID:20959623

  2. LOCAL SIGNALING FROM A RETINAL PROSTHETIC IN A RODENT RETINITIS PIGMENTOSA MODEL IN VIVO

    PubMed Central

    Fransen, James W.; Pangeni, Gobinda; Pardue, Machelle T.; McCall, Maureen A.

    2014-01-01

    Objective In clinical trials, retinitis pigmentosa (RP) patients implanted with a retinal prosthetic device show enhanced spatial vision, including the ability to read large text and navigate. New prosthetics aim to increase spatial resolution by decreasing pixel/electrode size and limiting current spread. To examine spatial resolution of a new prosthetic design, we characterized and compared two photovoltaic array (PVA) designs and their interaction with the retina after subretinal implantation in transgenic S334ter line 3 rats (Tg S334ter-3). Approach PVAs were implanted subretinally at two stages of degeneration and assessed in vivo using extracellular recordings in the superior colliculus (SC). Several aspects of this interaction were evaluated by varying duration, irradiance and position of a near infrared (NIR) laser focused on the PVA. These characteristics included: activation threshold, response linearity, SC signal topography and spatial localization. The major design difference between the two PVA designs is the inclusion of local current returns in the newer design. Main Results When tested in vivo, PVA-evoked response thresholds were independent of pixel/electrode size, but differ between the new and old PVA designs. Response thresholds were independent of implantation age and duration (≤ 7.5 months). For both prosthesis designs, threshold intensities were within established safety limits. PVA-evoked responses require inner retina synaptic transmission and do not directly activate retinal ganglion cells (RGCs). The new PVA design evokes local retinal activation, which is not found with the older PVA design that lacks local current returns. Significance Our study provides in vivo evidence that prosthetics make functional contacts with the inner nuclear layer at several stages of degeneration. The new PVA design enhances local activation within the retina and SC. Together these results predict that the new design can potentially harness the inherent

  3. Local signaling from a retinal prosthetic in a rodent retinitis pigmentosa model in vivo

    NASA Astrophysics Data System (ADS)

    Fransen, James W.; Pangeni, Gobinda; Pardue, Machelle T.; McCall, Maureen A.

    2014-08-01

    Objective. In clinical trials, retinitis pigmentosa patients implanted with a retinal prosthetic device show enhanced spatial vision, including the ability to read large text and navigate. New prosthetics aim to increase spatial resolution by decreasing pixel/electrode size and limiting current spread. To examine spatial resolution of a new prosthetic design, we characterized and compared two photovoltaic array (PVA) designs and their interaction with the retina after subretinal implantation in transgenic S334ter line 3 rats (Tg S334ter-3). Approach. PVAs were implanted subretinally at two stages of degeneration and assessed in vivo using extracellular recordings in the superior colliculus (SC). Several aspects of this interaction were evaluated by varying duration, irradiance and position of a near infrared laser focused on the PVA. These characteristics included: activation threshold, response linearity, SC signal topography and spatial localization. The major design difference between the two PVA designs is the inclusion of local current returns in the newer design. Main results. When tested in vivo, PVA-evoked response thresholds were independent of pixel/electrode size, but differ between the new and old PVA designs. Response thresholds were independent of implantation age and duration (⩽7.5 months). For both prosthesis designs, threshold intensities were within established safety limits. PVA-evoked responses require inner retina synaptic transmission and do not directly activate retinal ganglion cells. The new PVA design evokes local retinal activation, which is not found with the older PVA design that lacks local current returns. Significance. Our study provides in vivo evidence that prosthetics make functional contacts with the inner nuclear layer at several stages of degeneration. The new PVA design enhances local activation within the retina and SC. Together these results predict that the new design can potentially harness the inherent processing within

  4. The homogeneity of the retinal illumination is restricted by some ERG lenses.

    PubMed

    Kooijman, A C

    1986-03-01

    Are all types of available electroretinographic contact lenses suited for Ganzfeld stimulation? To answer this question, calculations have been made of the retinal light distribution with several types of ERG lenses placed on a theoretical eye. The results make possible a division of the ERG lenses into three categories. Category 1: Lenses with which the homogeneity of the retinal illumination is nearly perfect and independent of pupil size. These lenses are especially well designed for Ganzfeld electroretinography. Category 2: Lenses which illuminate a large retinal area but with which the light distribution depends on the size of the pupil. The suitability of these lenses is questionable, because Ganzfeld electroretinography is used in order to obtain a homogeneous retinal light distribution under most conditions. Category 3: Lenses with which the size of the illuminated retinal area changes strongly with the size of the pupil. These lenses are unsuitable for Ganzfeld electroretinography. PMID:3949465

  5. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    In 2005, six companies mined fire clay in Missouri, Ohio and South Carolina. Production was estimate to be 300 kt with a value of $8.3 million. Missouri was the leading producer state followed by Ohio and South Carolina. For the third consecutive year, sales and use of fire clays have been relatively unchanged. For the next few years, sales of fire clay is forecasted to remain around 300 kt/a.

  6. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the fire clay industry, particularly in the U.S., as of June 2011. It claims that the leading fire clay producer in the U.S. is the state of Missouri. The other major producers include California, Texas and Washington. It reports that the use of heavy clay products made of fire clay like brick, cement and lightweight aggregate has increased slightly in 2010.

  7. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  8. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  9. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  10. 46 CFR 95.10-5 - Fire pumps.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Fire pumps. 95.10-5 Section 95.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS FIRE PROTECTION EQUIPMENT Fire Main System, Details § 95.10-5 Fire pumps. (a) Vessels shall be equipped with independently driven...

  11. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2013-01-01

    Four companies mined fire clay in three states in 2012. Production, based on a preliminary survey of the fire clay industry, was estimated to be 230 kt (254,000 st) valued at $6.98 million, an increase from 215 kt (237,000 st) valued at $6.15 million in 2011. Missouri was the leading producing state, followed by Colorado and Texas, in decreasing order by quantity. The number of companies mining fire clay declined in 2012 because several common clay producers that occasionally mine fire clay indicated that they did not do so in 2012.

  12. Polymodal Sensory Integration in Retinal Ganglion Cells.

    PubMed

    Križaj, David

    2016-01-01

    An animal's ability to perceive the external world is conditioned by its capacity to extract and encode specific features of the visual image. The output of the vertebrate retina is not a simple representation of the 2D visual map generated by photon absorptions in the photoreceptor layer. Rather, spatial, temporal, direction selectivity and color "dimensions" of the original image are distributed in the form of parallel output channels mediated by distinct retinal ganglion cell (RGC) populations. We propose that visual information transmitted to the brain includes additional, light-independent, inputs that reflect the functional states of the retina, anterior eye and the body. These may include the local ion microenvironment, glial metabolism and systemic parameters such as intraocular pressure, temperature and immune activation which act on ion channels that are intrinsic to RGCs. We particularly focus on light-independent mechanical inputs that are associated with physical impact, cell swelling and intraocular pressure as excessive mechanical stimuli lead to the counterintuitive experience of "pressure phosphenes" and/or debilitating blinding disease such as glaucoma and diabetic retinopathy. We point at recently discovered retinal mechanosensitive ion channels as examples through which molecular physiology brings together Greek phenomenology, modern neuroscience and medicine. Thus, RGC output represents a unified picture of the embodied context within which vision takes place. PMID:26427477

  13. PIMASERTIB AND SEROUS RETINAL DETACHMENTS

    PubMed Central

    AlAli, Alaa; Bushehri, Ahmad; Park, Jonathan C.; Krema, Hatem

    2016-01-01

    Purpose: To report a case of multifocal serous retinal detachments associated with pimasertib. Methods: The authors report a 26-year-old patient who developed bilateral multifocal serous retinal detachments appearing 2 days after starting pimasertib (as part of a clinical trial investigating its use in low-grade metastatic ovarian cancer) and rapidly resolving 3 days after stopping it. Conclusion: The mechanism of MEK inhibitor induced visual toxicity remains unclear. The pathophysiology of multifocal serous retinal detachments as a complication of pimasertib is still poorly understood. PMID:26444523

  14. Retinal representation of the elementary visual signal

    PubMed Central

    Li, Peter H.; Field, Greg D.; Greschner, Martin; Ahn, Daniel; Gunning, Deborah E.; Mathieson, Keith; Sher, Alexander; Litke, Alan M.; Chichilnisky, E.J.

    2014-01-01

    Summary The propagation of visual signals from individual cone photoreceptors through parallel neural circuits was examined in the primate retina. Targeted stimulation of individual cones was combined with simultaneous recording from multiple retinal ganglion cells of identified types. The visual signal initiated by an individual cone produced strong responses with different kinetics in three of the four numerically dominant ganglion cell types. The magnitude and kinetics of light responses in each ganglion cell varied nonlinearly with stimulus strength, but in a manner that was independent of the cone of origin after accounting for the overall input strength of each cone. Based on this property of independence, the receptive field profile of an individual ganglion cell could be well estimated from responses to stimulation of each cone individually. Together these findings provide a quantitative account of how elementary visual inputs form the ganglion cell receptive field. PMID:24411737

  15. Arizona Fires

    Atmospheric Science Data Center

    2014-05-15

    ... the second largest fire in Arizona history. More than 2,000 people are working to contain the fire, which is being driven by high winds and ... bright desert background. The areas with no data (shown in black and present at the oblique angles) are locations where the variable ...

  16. Returning Fire

    ERIC Educational Resources Information Center

    Gould, Jon B.

    2007-01-01

    Last December saw another predictable report from the Foundation for Individual Rights in Education (FIRE), a self-described watchdog group, highlighting how higher education is supposedly under siege from a politically correct plague of so-called hate-speech codes. In that report, FIRE declared that as many as 96 percent of top-ranked colleges…

  17. Fire Power

    ERIC Educational Resources Information Center

    Denker, Deb; West, Lee

    2009-01-01

    For education administrators, campus fires are not only a distressing loss, but also a stark reminder that a campus faces risks that require special vigilance. In many ways, campuses resemble small communities, with areas for living, working and relaxing. A residence hall fire may raise the specter of careless youth, often with the complication of…

  18. Siberian Fires

    Atmospheric Science Data Center

    2013-04-16

    ... of fires across Siberia and the Russian Far East, northeast China and northern Mongolia. Fires in Eastern Siberia have been increasing in ... spatial contrast. The heights correspond to elevations above sea level. Taking into account the surface elevation, the smoke plumes range ...

  19. Binocular retinal image differences influence eye-position signals for perceived visual direction.

    PubMed

    Sridhar, Deepika; Bedell, Harold E

    2012-06-01

    Correctly perceiving the direction of a visible object with respect to one's self (egocentric visual direction) requires that information about the location of the image on the retina (oculocentric visual direction) be combined with signals about the position of the eyes in the head. The Wells-Hering laws that govern the perception of visual direction and modern restatements of these laws assume implicitly that retinal and eye-position information are independent of one another. By measuring observers' manual pointing responses to targets in different horizontal locations, we show that retinal and eye-position information are not treated independently in the brain. In particular, decreasing the relative visibility of one eye's retinal image reduces the strength of the eye-position signal associated with that eye. The results can be accounted for by interactions between eye-specific retinal and eye-position signals at a common neural location. PMID:22560955

  20. Building retinal connectomes.

    PubMed

    Marc, Robert E; Jones, Bryan W; Lauritzen, J Scott; Watt, Carl B; Anderson, James R

    2012-08-01

    Understanding vertebrate vision depends on knowing, in part, the complete network graph of at least one representative retina. Acquiring such graphs is the business of synaptic connectomics, emerging as a practical technology due to improvements in electron imaging platform control, management software for large-scale datasets, and availability of data storage. The optimal strategy for building complete connectomes uses transmission electron imaging with 2 nm or better resolution, molecular tags for cell identification, open-access data volumes for navigation, and annotation with open-source tools to build 3D cell libraries, complete network diagrams and connectivity databases. The first forays into retinal connectomics have shown that even nominally well-studied cells have much richer connection graphs than expected. PMID:22498714

  1. 46 CFR 28.315 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... After September 15, 1991, and That Operate With More Than 16 Individuals on Board § 28.315 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel 36 feet (11.8 meters) or more in length...

  2. 46 CFR 28.820 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.820 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel must be equipped with a self-priming, power driven...

  3. 46 CFR 28.820 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.820 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel must be equipped with a self-priming, power driven...

  4. Nutrition and retinal degenerations.

    PubMed

    Berson, E L

    2000-01-01

    Considerable progress has been made in the understanding and management of degenerative diseases of the retina involving photoreceptors. Nutritional approaches to treatment have proved successful in the case of the common forms of retinitis pigmentosa (supplementation with vitamin A), Bassen-Kornzweig disease (supplementation with vitamins A, E, and K), gyrate atrophy (low-protein, low-arginine diet and/or supplementation with vitamin B6), and Refsum disease (low-phytol, low-phytanic acid diet). The night blindness associated with Sorsby fundus dystrophy can be reversed over the short term with vitamin A. A significant trend for decreased risk for advanced or exudative ARMD has been reported among those whose diets contain a higher content of carotenoids, such as spinach and collard greens. A randomized trial is in progress to determine whether beta-carotene, vitamin C, and vitamin E as well as trace minerals, particularly zinc, will modify the course of ARMD. The difficulties that patients with retinal degenerations face as a result of their diminishing vision, sometimes over decades, cannot be underestimated. Nutritional therapy has proved effective in modifying the course of a number of these conditions; the therapeutic benefit of nutritional modification in diseases that have a genetic basis is of particular interest. Further research is warranted to determine the mechanisms by which these treatments provide their benefit as well as to identify other conditions that may yield to nutritional intervention. Risk-factor analyses of well-defined populations followed over time with food-frequency questionnaires in conjunction with careful assessments of visual function may reveal other dietary constituents that can modify the course of degenerative diseases of the retina. PMID:11064860

  5. Molecular genetics of retinitis pigmentosa.

    PubMed Central

    Farber, D. B.; Heckenlively, J. R.; Sparkes, R. S.; Bateman, J. B.

    1991-01-01

    Retinitis pigmentosa is a model for the study of genetic diseases. Its genetic heterogeneity is reflected in the different forms of inheritance (autosomal dominant, autosomal recessive, or X-linked) and, in a few families, in the presence of mutations in the visual pigment rhodopsin. Clinical and molecular genetic studies of these disorders are discussed. Animal models of retinal degeneration have been investigated for many years with the hope of gaining insight into the cause of photoreceptor cell death. Recently, the genes responsible for two of these animal disorders, the rds and rd mouse genes, have been isolated and characterized. The retinal degeneration of the rd mouse is presented in detail. The possible involvement of human analogues of these mouse genes in human retinal diseases is being investigated. Images PMID:1771877

  6. Noise-robust low-contrast retinal recognition using compression-based joint wavelet transform correlator

    NASA Astrophysics Data System (ADS)

    Widjaja, Joewono

    2015-11-01

    A new method is proposed for recognizing noise corrupted low-contrast retinal images that employs joint wavelet transform correlator with compressed reference and target. Noise robustness is achieved by correlating wavelet-transformed retinal target and reference images. Simulation results show that besides being robust to noise, its recognition performance can become independent upon compression qualities when low spatial-frequency components of joint power spectrum are enhanced by appropriately dilated wavelet filter.

  7. Microsystems Technology for Retinal Implants

    NASA Astrophysics Data System (ADS)

    Weiland, James

    2005-03-01

    The retinal prosthesis is targeted to treat age-related macular degeneration, retinitis pigmentosa, and other outer retinal degenerations. Simulations of artificial vision have predicted that 600-1000 individual pixels will be needed if a retinal prosthesis is to restore function such as reading large print and face recognition. An implantable device with this many electrode contacts will require microsystems technology as part of its design. An implantable retinal prosthesis will consist of several subsystems including an electrode array and hermetic packaging. Microsystems and microtechnology approaches are being investigated as possible solutions for these design problems. Flexible polydimethylsiloxane (PDMS) substrate electrode arrays and silicon micromachined electrode arrays are under development. Inactive PDMS electrodes have been implanted in 3 dogs to assess mechanical biocompatibility. 3 dogs were followed for 6 months. The implanted was securely fastened to the retina with a single retinal tack. No post-operative complications were evident. The array remained within 100 microns of the retinal surface. Histological evaluation showed a well preserved retina underneath the electrode array. A silicon device with electrodes suspended on micromachined springs has been implanted in 4 dogs (2 acute implants, 2 chronic implants). The device, though large, could be inserted into the eye and positioned on the retina. Histological analysis of the retina from the spring electrode implants showed that spring mounted posts penetrated the retina, thus the device will be redesigned to reduce the strength of the springs. These initial implants will provide information for the designers to make the next generation silicon device. We conclude that microsystems technology has the potential to make possible a retinal prosthesis with 1000 individual contacts in close proximity to the retina.

  8. Spacecraft Fire Safety

    NASA Technical Reports Server (NTRS)

    Margle, Janice M. (Editor)

    1987-01-01

    Fire detection, fire standards and testing, fire extinguishment, inerting and atmospheres, fire-related medical science, aircraft fire safety, Space Station safety concerns, microgravity combustion, spacecraft material flammability testing, and metal combustion are among the topics considered.

  9. Retinal oxygen extraction in humans

    NASA Astrophysics Data System (ADS)

    Werkmeister, René M.; Schmidl, Doreen; Aschinger, Gerold; Doblhoff-Dier, Veronika; Palkovits, Stefan; Wirth, Magdalena; Garhöfer, Gerhard; Linsenmeier, Robert A.; Leitgeb, Rainer A.; Schmetterer, Leopold

    2015-10-01

    Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy.

  10. General pathophysiology in retinal degeneration.

    PubMed

    Wert, Katherine J; Lin, Jonathan H; Tsang, Stephen H

    2014-01-01

    Retinal degeneration, including that seen in age-related macular degeneration and retinitis pigmentosa (RP), is the most common form of neural degenerative disease in the world. There is great genetic and allelic heterogeneity of the various retinal dystrophies. Classifications of these diseases can be ambiguous, as there are similar clinical presentations in retinal degenerations arising from different genetic mechanisms. As would be expected, alterations in the activity of the phototransduction cascade, such as changes affecting the renewal and shedding of the photoreceptor OS, visual transduction, and/or retinol metabolism have a great impact on the health of the retina. Mutations within any of the molecules responsible for these visual processes cause several types of retinal and retinal pigment epithelium degenerative diseases. Apoptosis has been implicated in the rod cell loss seen in a mouse model of RP, but the precise mechanisms that connect the activation of these pathways to the loss of phosphodiesterase (PDE6β) function has yet to be defined. Additionally, the activation of apoptosis by CCAAT/-enhancer-binding protein homologous protein (CHOP), after activation of the unfolded protein response pathway, may be responsible for cell death, although the mechanism remains unknown. However, the mechanisms of cell death after loss of function of PDE6, which is a commonly studied mammalian model in research, may be generalizable to loss of function of different key proteins involved in the phototransduction cascade. PMID:24732759

  11. General Pathophysiology in Retinal Degeneration

    PubMed Central

    Wert, Katherine J.; Lin, Jonathan H.; Tsang, Stephen H.

    2015-01-01

    Retinal degeneration, including that seen in age-related macular degeneration and retinitis pigmentosa (RP), is the most common form of neural degenerative disease in the world. There is great genetic and allelic heterogeneity of the various retinal dystrophies. Classifications of these diseases can be ambiguous, as there are similar clinical presentations in retinal degenerations arising from different genetic mechanisms. As would be expected, alterations in the activity of the phototransduction cascade, such as changes affecting the renewal and shedding of the photoreceptor OS, visual transduction, and/ or retinol metabolism have a great impact on the health of the retina. Mutations within any of the molecules responsible for these visual processes cause several types of retinal and retinal pigment epithelium degenerative diseases. Apoptosis has been implicated in the rod cell loss seen in a mouse model of RP, but the precise mechanisms that connect the activation of these pathways to the loss of phosphodiesterase (PDE6β) function has yet to be defined. Additionally, the activation of apoptosis by CCAAT/-enhancer-binding protein homologous protein (CHOP), after activation of the unfolded protein response pathway, may be responsible for cell death, although the mechanism remains unknown. However, the mechanisms of cell death after loss of function of PDE6, which is a commonly studied mammalian model in research, may be generalizable to loss of function of different key proteins involved in the phototransduction cascade. PMID:24732759

  12. The mechanics of retinal detachment

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Siegel, Michael

    2013-03-01

    We present a model of the mechanical and fluid forces associated with exudative retinal detachments where the retinal photoreceptor cells separate typically from the underlying retinal pigment epithelium (RPE). By computing the total fluid volume flow arising from transretinal, vascular, and retinal pigment epithelium (RPE) pump currents, we determine the conditions under which the subretinal fluid pressure exceeds the maximum yield stress holding the retina and RPE together, giving rise to an irreversible, extended retinal delamination. We also investigate localized, blister-like retinal detachments by balancing mechanical tension in the retina with both the retina-RPE adhesion energy and the hydraulic pressure jump across the retina. For detachments induced by traction forces, we find a critical radius beyond which the blister is unstable to growth. Growth of a detached blister can also be driven by inflamed tissue within which e.g., the hydraulic conductivities of the retina or choroid increase, the RPE pumps fail, or the adhesion properties change. We determine the parameter regimes in which the blister either becomes unstable to growth, remains stable and finite-sized, or shrinks, allowing possible healing. This work supported by the Army Research Office through grant 58386MA

  13. Cytomegalovirus retinitis mimicking intraocular lymphoma.

    PubMed

    Gooi, Patrick; Farmer, James; Hurley, Bernard; Brodbaker, Elliott

    2008-12-01

    We present a case of an unusual retinal infiltrate requiring retinal biopsy for definitive diagnosis. A 62-year-old man with treated lymphoma presented with decreased vision in the right eye associated with a white retinal lesion, which extended inferonasally from an edematous disc. Intraocular lymphoma was considered as a diagnosis; thus, the patient was managed with vitrectomy and retinal biopsy. Cytological analysis of the vitreous aspirate could not rule out a lymphoproliferative disorder. The microbial analysis was negative. Histology of the lesion showed extensive necrosis and large cells with prominent nucleoli. To rule out lymphoma, a battery of immunostains was performed and all were negative. However the limited amount of tissue was exhausted in the process. Subsequently, a hematoxylin and eosin (H/E) slide was destained, on which a CMV immunostain was performed. This revealed positivity in the nuclei and intranuclear inclusions within the large atypical cells. A diagnosis of CMV retinitis was made. Retinal biopsy may provide a definitive diagnosis and direct patient care toward intravenous gancyclovir in the case of CMV or toward radiation and chemotherapy for intraocular lymphoma. When faced with a limited amount of tissue, destaining regular H/E slides is a possible avenue to performing additional immunohistochemical studies. PMID:19668455

  14. Retinal oxygen extraction in humans.

    PubMed

    Werkmeister, René M; Schmidl, Doreen; Aschinger, Gerold; Doblhoff-Dier, Veronika; Palkovits, Stefan; Wirth, Magdalena; Garhöfer, Gerhard; Linsenmeier, Robert A; Leitgeb, Rainer A; Schmetterer, Leopold

    2015-01-01

    Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy. PMID:26503332

  15. Retinal oxygen extraction in humans

    PubMed Central

    Werkmeister, René M.; Schmidl, Doreen; Aschinger, Gerold; Doblhoff-Dier, Veronika; Palkovits, Stefan; Wirth, Magdalena; Garhöfer, Gerhard; Linsenmeier, Robert A.; Leitgeb, Rainer A.; Schmetterer, Leopold

    2015-01-01

    Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy. PMID:26503332

  16. Genetically Identified Suppressed-by-Contrast Retinal Ganglion Cells Reliably Signal Self-Generated Visual Stimuli

    PubMed Central

    Tien, Nai-Wen; Pearson, James T.; Heller, Charles R.; Demas, Jay

    2015-01-01

    Spike trains of retinal ganglion cells (RGCs) are the sole source of visual information to the brain; and understanding how the ∼20 RGC types in mammalian retinae respond to diverse visual features and events is fundamental to understanding vision. Suppressed-by-contrast (SbC) RGCs stand apart from all other RGC types in that they reduce rather than increase firing rates in response to light increments (ON) and decrements (OFF). Here, we genetically identify and morphologically characterize SbC-RGCs in mice, and target them for patch-clamp recordings under two-photon guidance. We find that strong ON inhibition (glycine > GABA) outweighs weak ON excitation, and that inhibition (glycine > GABA) coincides with decreases in excitation at light OFF. These input patterns explain the suppressive spike responses of SbC-RGCs, which are observed in dim and bright light conditions. Inhibition to SbC-RGC is driven by rectified receptive field subunits, leading us to hypothesize that SbC-RGCs could signal pattern-independent changes in the retinal image. Indeed, we find that shifts of random textures matching saccade-like eye movements in mice elicit robust inhibitory inputs and suppress spiking of SbC-RGCs over a wide range of texture contrasts and spatial frequencies. Similarly, stimuli based on kinematic analyses of mouse blinking consistently suppress SbC-RGC spiking. Receiver operating characteristics show that SbC-RGCs are reliable indicators of self-generated visual stimuli that may contribute to central processing of blinks and saccades. SIGNIFICANCE STATEMENT This study genetically identifies and morphologically characterizes suppressed-by-contrast retinal ganglion cells (SbC-RGCs) in mice. Targeted patch-clamp recordings from SbC-RGCs under two-photon guidance elucidate the synaptic mechanisms mediating spike suppression to contrast steps, and reveal that SbC-RGCs respond reliably to stimuli mimicking saccade-like eye movements and blinks. The similarity of

  17. Cannabinoid and lipid-mediated vasorelaxation in retinal microvasculature.

    PubMed

    MacIntyre, Jessica; Dong, Alex; Straiker, Alex; Zhu, Jiequan; Howlett, Susan E; Bagher, Amina; Denovan-Wright, Eileen; Yu, Dao-Yi; Kelly, Melanie E M

    2014-07-15

    The endocannabinoid system plays a role in regulation of vasoactivity in the peripheral vasculature; however, little is known about its role in regulation of the CNS microvasculature. This study investigated the pharmacology of cannabinoids and cannabimimetic lipids in the retinal microvasculature, a CNS vascular bed that is autoregulated. Vessel diameter (edge detector) and calcium transients (fura-2) were recorded from segments of retinal microvasculature isolated from adult, male Fischer 344 rats. Results showed that abnormal cannabidiol (Abn-CBD), an agonist at the putative endothelial cannabinoid receptor, CBe, inhibited endothelin 1 (ET-1) induced vasoconstriction in retinal arterioles. These actions of Abn-CBD were independent of CB1/CB2 receptors and were not mediated by agonists for GPR55 or affected by nitric oxide synthase (NOS) inhibition. However, the vasorelaxant effects of Abn-CBD were abolished when the endothelium was removed and were inhibited by the small Ca(2+)-sensitive K channel (SKCa) blocker, apamin. The effects of the endogenous endocannabinoid metabolite, N-arachidonyl glycine (NAGly), a putative agonist for GPR18, were virtually identical to those of Abn-CBD. GPR18 mRNA and protein were present in the retina, and immunohistochemistry demonstrated that GPR18 was localized to the endothelium of retinal vessels. These findings demonstrate that Abn-CBD and NAGly inhibit ET-1 induced vasoconstriction in retinal arterioles by an endothelium-dependent signaling mechanism that involves SKCa channels. The endothelial localization of GPR18 suggests that GPR18 could contribute to cannabinoid and lipid-mediated retinal vasoactivity. PMID:24751709

  18. Correlation in the Discharges of Neighboring Rat Retinal Ganglion Cells During Prenatal Life

    NASA Astrophysics Data System (ADS)

    Maffei, Lamberto; Galli-Resta, Lucia

    1990-04-01

    The spontaneous discharges of neighboring retinal ganglion cells were recorded simultaneously in anesthetized prenatal rats between embryonic days 18 and 21. We report here that in the majority of cases the firings of neighboring retinal ganglion cells are strongly correlated during prenatal life. Correlation in the discharges of neighboring cells during development has long been suggested as a way to consolidate synaptic connections with a target cell onto which they converge, a model first proposed by Hebb. Correlation in the activities of neighboring neurons in the retina could be the basis of developmental processes such as refinement of retinotopic maps in the brain and segregation of the inputs from the two eyes.

  19. Mexico Fires

    Atmospheric Science Data Center

    2013-04-18

    article title:  Smoke from Fires in Southern Mexico     View Larger Image ... southern Mexico sent smoke drifting northward over the Gulf of Mexico. These views from the Multi-angle Imaging SpectroRadiometer (MISR) ...

  20. California Fires

    Atmospheric Science Data Center

    2014-05-15

    ... title:  Smoke from Station Fire Blankets Southern California     View Larger Image ... that had not burned in decades, and years of extended drought contributed to the explosive growth of wildfires throughout southern ...

  1. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2012-01-01

    Five companies mined fire clay in four states in 2011. Production, based on a preliminary survey of the fire clay industry, was estimated to be 240 kt (265,000 st), valued at $7.68 million, an increase from 216 kt (238,000 st), valued at $6.12 million in 2010. Missouri was the leading producing state, followed by Texas, Washington and Ohio, in decreasing order by quantity.

  2. 46 CFR 28.820 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... water from a hose connected to the highest outlet. The minimum capacity of the power fire pump shall be... 46 Shipping 1 2012-10-01 2012-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.820 Fire pumps, fire...

  3. 46 CFR 28.820 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... water from a hose connected to the highest outlet. The minimum capacity of the power fire pump shall be... 46 Shipping 1 2011-10-01 2011-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.820 Fire pumps, fire...

  4. 46 CFR 28.820 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .../capacity, and is properly equipped to handle both fire fighting and flood control. (b) Each vessel must... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.820 Fire pumps, fire...

  5. Retinal AO OCT

    NASA Astrophysics Data System (ADS)

    Zawadzki, Robert J.; Miller, Donald T.

    The last two decades have witnessed extraordinary advances in optical technology to image noninvasively and at high resolution the posterior segment of the eye. Two of the most impactful technological advancements over this period have arguably been optical coherence tomography (OCT) and adaptive optics (AO). The strengths of these technologies complement each other and when combined have been shown to provide unprecedented, micron-scale resolution (<3 μm) in all three dimensions and sensitivity to image the cellular retina in the living eye. This powerful extension of OCT, that is AO-OCT, is the focus of this chapter. It presents key aspects of designing and implementing AO-OCT systems. Particular attention is devoted to the relevant optical properties of the eye that ultimately define these systems, AO componentry and operation tailored for ophthalmic use, and of course use of the latest technologies and methods in OCT for ocular imaging. It surveys the wide range of AO-OCT designs that have been developed for retinal imaging, with AO integrated into every major OCT design configuration. Finally, it reviews the scientific and clinical studies reported to date that show the exciting potential of AO-OCT to image the microscopic retina and fundus in ways not previously possible with other noninvasive methods and a look to future developments in this rapidly growing field.

  6. Color Doppler imaging of retinal diseases.

    PubMed

    Dimitrova, Galina; Kato, Satoshi

    2010-01-01

    Color Doppler imaging (CDI) is a widely used method for evaluating ocular circulation that has been used in a number of studies on retinal diseases. CDI assesses blood velocity parameters by using ultrasound waves. In ophthalmology, these assessments are mainly performed on the retrobulbar blood vessels: the ophthalmic, the central retinal, and the short posterior ciliary arteries. In this review, we discuss CDI use for the assessment of retinal diseases classified into the following: vascular diseases, degenerations, dystrophies, and detachment. The retinal vascular diseases that have been investigated by CDI include diabetic retinopathy, retinal vein occlusions, retinal artery occlusions, ocular ischemic conditions, and retinopathy of prematurity. Degenerations and dystrophies included in this review are age-related macular degeneration, myopia, and retinitis pigmentosa. CDI has been used for the differential diagnosis of retinal detachment, as well as the evaluation of retrobulbar circulation in this condition. CDI is valuable for research and is a potentially useful diagnostic tool in the clinical setting. PMID:20385332

  7. Photon Echoes from Retinal Proteins

    NASA Astrophysics Data System (ADS)

    Johnson, Philip James Maddigan

    This thesis focuses on the ultrafast isomerization reaction of retinal in both rhodopsin and bacteriorhodopsin, examples of sensory and energy transduction proteins that exploit the same photoactive chromophore for two very different functions. In bacteriorhodopsin, retinal isomerizes from an all-trans to 13-cis conformation as the primary event in light- driven proton pumping. In the visual pigment rhodopsin, the retinal chromophore isomerizes from an 11-cis to all-trans geometry as the primary step leading to our sense of vision. This diversity of function for nominally identical systems raises the question as to just how optimized are these proteins to arrive at such drastically different functions? Previous work has employed transient absorption spectroscopy to probe retinal protein photochemistry, but many of the relevant electronic and nuclear dynamics of isomerization are masked by inhomogeneous broadening effects and strong spectral overlap between reactant and photoproduct states. This work exploits the unique properties of two-dimensional photon echo spectroscopy to deconvolve inhomogeneous broadening and spectral overlap effects and fully reveal the dynamics that direct retinal isomerization in proteins. In bacteriorhodopsin, vibrational coupling to the reaction coordinate results in a surface crossing event prior to the conventional conical intersection associated with isomerization to the J intermediate. In rhodopsin, however, a similarly early vibrationally-mediated barrier crossing event is observed, resulting in spectral signals consistent with the known photoproduct state appearing an order of magnitude faster than determined from conventional transient absorption measurements. The competing overlapping spectral signals that obscured the initial dynamics when probed with transient absorption spectroscopy are now clearly resolved with two-dimensional photon echo spectroscopy. These experiments illustrate the critical role of the protein in directing

  8. Automated retinal robotic laser system.

    PubMed

    Barrett, S F; Wright, C H; Jerath, M R; Lewis, R S; Dillard, B C; Rylander, H G; Welch, A J

    1995-01-01

    Researchers at the University of Texas and the USAF Academy have worked toward the development of a retinal robotic laser system. The overall goal of this ongoing project is to precisely place and control the depth of laser lesions for the treatment of various retinal diseases such as diabetic retinopathy and retinal tears. Separate low speed prototype subsystems have been developed to control lesion depth using lesion reflectance feedback parameters and lesion placement using retinal vessels as tracking landmarks. Both subsystems have been successfully demonstrated in vivo on pigmented rabbits using an argon continuous wave laser. Recent efforts have concentrated on combining the two subsystems into a single prototype capable of simultaneously controlling both lesion depth and placement. We have designated this combined system CALOSOS for Computer Aided Laser Optics System for Ophthalmic Surgery. Following the dual-use concept, this system is being adapted for clinical use as a retinal treatment system as well as a research tool for military laser-tissue interaction studies. PMID:7654990

  9. Neuroglobin Protection in Retinal Ischemia

    PubMed Central

    Chan, Anita S.Y.; Saraswathy, Sindhu; Rehak, Matus; Ueki, Mari

    2012-01-01

    Purpose. Neuroglobin (Ngb) is a vertebrate globin that is predominantly expressed in the retina and brain. To explore the role of Ngb in retinal neuroprotection during ischemia reperfusion (IR), the authors examined the effect of Ngb overexpression in the retina in vivo by using Ngb-transgenic (Ngb-Tg) mice. Methods. Retinal IR was induced in Ngb overexpressing Ngb-Tg mice and wild type (WT) mice by cannulating the anterior chamber and transiently elevating the IOP for 60 minutes. After Day 7 of reperfusion, the authors evaluated Ngb mRNA and protein expression in nonischemic control as well as ischemic mice and its effect on retinal histology, mitochondrial oxidative stress, and apoptosis, using morphometry and immunohistochemistry, quantitative PCR analysis and Western blot techniques. Results. Ngb-Tg mice without ischemia overexpress Ngb mRNA 11.3-fold (SE ± 0.457, P < 0.05) higher than WT control mice, and this overexpression of Ngb protein was localized to the mitochondria of the ganglion cells, outer and inner plexiform layers, and photoreceptor inner segments. This overexpression of Ngb is associated with decreased mitochondrial DNA damage in Ngb-Tg mice with IR in comparison with WT. Ngb-Tg mice with IR also revealed significant preservation of retinal thickness, significantly less activated caspase 3 protein expression, and apoptosis in comparison with WT mice. Conclusions. Neuroglobin overexpression plays a neuroprotective role against retinal ischemia reperfusion injury due to decreasing of mitochondrial oxidative stress-mediated apoptosis. PMID:22167093

  10. Vinpocetine modulates metabolic activity and function during retinal ischemia.

    PubMed

    Nivison-Smith, Lisa; O'Brien, Brendan J; Truong, Mai; Guo, Cindy X; Kalloniatis, Michael; Acosta, Monica L

    2015-05-01

    Vinpocetine protects against a range of degenerative conditions and insults of the central nervous system via multiple modes of action. Little is known, however, of its effects on metabolism. This may be highly relevant, as vinpocetine is highly protective against ischemia, a process that inhibits normal metabolic function. This study uses the ischemic retina as a model to characterize vinpocetine's effects on metabolism. Vinpocetine reduced the metabolic demand of the retina following ex vivo hypoxia and ischemia to normal levels based on lactate dehydrogenase activity. Vinpocetine delivered similar effects in an in vivo model of retinal ischemia-reperfusion, possibly through increasing glucose availability. Vinpocetine's effects on glucose also appeared to improve glutamate homeostasis in ischemic Müller cells. Other actions of vinpocetine following ischemia-reperfusion, such as reduced cell death and improved retinal function, were possibly a combination of the drug's actions on metabolism and other retinal pathways. Vinpocetine's metabolic effects appeared independent of its other known actions in ischemia, as it recovered retinal function in a separate metabolic model where the glutamate-to-glutamine metabolic pathway was inhibited in Müller cells. The results of this study indicate that vinpocetine mediates ischemic damage partly through altered metabolism and has potential beneficial effects as a treatment for ischemia of neuronal tissues. PMID:25696811

  11. [Unusual retinal abnormality: retinal hemorrhages related to scurvy].

    PubMed

    Errera, M-H; Dupas, B; Man, H; Gualino, V; Gaudric, A; Massin, P

    2011-03-01

    A diet restricted to rice and boiled fruit and vegetables leads to vitamin C deficiency. We describe the third case, to our knowledge, of retinal hemorrhages related to scurvy. Reduced bilateral visual acuity in a 50-year-old patient was associated with macrocytic anemia, denutrition, and cutaneous ecchymoses. Oral vitamin C treatment provided subjective clinical improvement and regression of the retinal hemorrhages on fundus examination, with no side effects. Vitamin C plays an important role in collagen stability in vascular and bone walls. PMID:21392843

  12. Transcorneal Electrical Stimulation Therapy for Retinal Disease

    ClinicalTrials.gov

    2012-05-03

    Retinitis Pigmentosa; Macula Off; Primary Open Angle Glaucoma; Hereditary Macular Degeneration; Treated Retina Detachment; Retinal Artery Occlusion; Retinal Vein Occlusion; Non-Arthritic-Anterior-Ischemic Optic-Neuropathy; Hereditary Autosomal Dominant Optic Atrophy; Dry Age Related Macular Degeneration; Ischemic Macula Edema

  13. Clinical Trials in Retinal Dystrophies

    PubMed Central

    Grob, Seanna R.; Finn, Avni; Papakostas, Thanos D.; Eliott, Dean

    2016-01-01

    Research development is burgeoning for genetic and cellular therapy for retinal dystrophies. These dystrophies are the focus of many research efforts due to the unique biology and accessibility of the eye, the transformative advances in ocular imaging technology that allows for in vivo monitoring, and the potential benefit people would gain from success in the field – the gift of renewed sight. Progress in the field has revealed the immense complexity of retinal dystrophies and the challenges faced by researchers in the development of this technology. This study reviews the current trials and advancements in genetic and cellular therapy in the treatment of retinal dystrophies and also discusses the current and potential future challenges. PMID:26957839

  14. Retinal spot size with wavelength

    NASA Astrophysics Data System (ADS)

    Rockwell, Benjamin A.; Hammer, Daniel X.; Kennedy, Paul K.; Amnotte, Rodney E.; Eilert, Brent; Druessel, Jeffrey J.; Payne, Dale J.; Phillips, Shana L.; Stolarski, David J.; Noojin, Gary D.; Thomas, Robert J.; Cain, Clarence P.

    1997-06-01

    We have made an indirect in-vivo determination of spot size focusing in the rhesus monkey model. Measurement of the laser induced breakdown threshold both in-vitro and in-vivo allow correlation and assignment of a spot size after focusing through the living eye. We discuss and analyze the results and show how trends in minimum visible lesion data should be assessed in light of chromatic aberration. National laser safety standards are based on minimal visual lesion (MVL) threshold studies in different animal models. The energy required for a retinal lesion depends upon may parameters including wavelength and retinal spot size. We attempt to explain trends in reported MVL threshold studies using a model of the eye which allows calculation of changes in retinal spot size due to chromatic aberration.

  15. Diabetes and Retinal Vascular Dysfunction

    PubMed Central

    Shin, Eui Seok; Sorenson, Christine M.; Sheibani, Nader

    2014-01-01

    Diabetes predominantly affects the microvascular circulation of the retina resulting in a range of structural changes unique to this tissue. These changes ultimately lead to altered permeability, hyperproliferation of endothelial cells and edema, and abnormal vascularization of the retina with resulting loss of vision. Enhanced production of inflammatory mediators and oxidative stress are primary insults with significant contribution to the pathogenesis of diabetic retinopathy (DR). We have determined the identity of the retinal vascular cells affected by hyperglycemia, and have delineated the cell autonomous impact of high glucose on function of these cells. We discuss some of the high glucose specific changes in retinal vascular cells and their contribution to retinal vascular dysfunction. This knowledge provides novel insight into the molecular and cellular defects contributing to the development and progression of diabetic retinopathy, and will aid in the development of innovative, as well as target specific therapeutic approaches for prevention and treatment of DR. PMID:25667739

  16. Exploring the retinal connectome

    PubMed Central

    Anderson, James R.; Jones, Bryan W.; Watt, Carl B.; Shaw, Margaret V.; Yang, Jia-Hui; DeMill, David; Lauritzen, James S.; Lin, Yanhua; Rapp, Kevin D.; Mastronarde, David; Koshevoy, Pavel; Grimm, Bradley; Tasdizen, Tolga; Whitaker, Ross

    2011-01-01

    Purpose A connectome is a comprehensive description of synaptic connectivity for a neural domain. Our goal was to produce a connectome data set for the inner plexiform layer of the mammalian retina. This paper describes our first retinal connectome, validates the method, and provides key initial findings. Methods We acquired and assembled a 16.5 terabyte connectome data set RC1 for the rabbit retina at ≈2 nm resolution using automated transmission electron microscope imaging, automated mosaicking, and automated volume registration. RC1 represents a column of tissue 0.25 mm in diameter, spanning the inner nuclear, inner plexiform, and ganglion cell layers. To enhance ultrastructural tracing, we included molecular markers for 4-aminobutyrate (GABA), glutamate, glycine, taurine, glutamine, and the in vivo activity marker, 1-amino-4-guanidobutane. This enabled us to distinguish GABAergic and glycinergic amacrine cells; to identify ON bipolar cells coupled to glycinergic cells; and to discriminate different kinds of bipolar, amacrine, and ganglion cells based on their molecular signatures and activity. The data set was explored and annotated with Viking, our multiuser navigation tool. Annotations were exported to additional applications to render cells, visualize network graphs, and query the database. Results Exploration of RC1 showed that the 2 nm resolution readily recapitulated well known connections and revealed several new features of retinal organization: (1) The well known AII amacrine cell pathway displayed more complexity than previously reported, with no less than 17 distinct signaling modes, including ribbon synapse inputs from OFF bipolar cells, wide-field ON cone bipolar cells and rod bipolar cells, and extensive input from cone-pathway amacrine cells. (2) The axons of most cone bipolar cells formed a distinct signal integration compartment, with ON cone bipolar cell axonal synapses targeting diverse cell types. Both ON and OFF bipolar cells receive

  17. Central retinal vein occlusion and pseudoexfoliation syndrome

    PubMed Central

    Karagiannis, Dimitrios; Kontadakis, Georgios A; Klados, Nektarios E; Tsoumpris, Ioannis; Kandarakis, Artemios S; Parikakis, Efstratios A; Georgalas, Ilias; Tsilimbaris, Miltiadis K

    2015-01-01

    Purpose The purpose of this study was to investigate the existence of pseudoexfoliation syndrome (PXF) as a risk factor for the development of central retinal vein occlusion (CRVO). Methods This was a retrospective, comparative study of the prevalence of pseudoexfoliation in three groups of patients: 48 patients with CRVO, 164 patients with branch retinal vein occlusion (BRVO), and 70 control patients (70 eyes). All patients were phakic and had no previous diagnosis of glaucoma. Patients were matched in terms of age and systemic hypertension. All patients had normal intraocular pressure (IOP) at presentation (defined as less than or equal to 21 mmHg). Results In the CRVO group, 14 out of 48 patients were diagnosed as having PXF (29.17%). In the BRVO group, 14 out of 164 patients had PXF (8.5%), and in the control group, six out of 70 patients had PXF (8.6%). Differences of percentage between groups were statistically significant (P<0.001, χ2 test). When comparing patient subgroup with ischemic CRVO with subgroup with non-ischemic CRVO, we found that in the ischemic CRVO group, 13 out of 27 patients were diagnosed as having PXF (48.15%), and in the non-ischemic CRVO group, one out of 21 patients was diagnosed as having PXF (4.7%; P<0.001, χ2 test). The relative odds of having CRVO in patients with PXF versus patients without PXF were 4.406 (confidence interval [CI], 2.03–9.54). Conclusion PXF and CRVO, especially ischemic, are strongly associated in our study. Our results indicate that PXF might be an independent factor for CRVO, as it is related with CRVO independently from glaucoma. PMID:26056437

  18. Mitochondrial Uncoupling Protein 2 (UCP2) Regulates Retinal Ganglion Cell Number and Survival.

    PubMed

    Barnstable, Colin J; Reddy, Rajini; Li, Hong; Horvath, Tamas L

    2016-04-01

    In the brain, mitochondrial uncoupling protein 2 (UCP2) has emerged as a stress signal associated with neuronal survival. In the retina, UCP2 is expressed primarily by retinal ganglion cells. Here, we investigated the functional relevance of UCP2 in the mouse retina. Increased expression of UCP2 significantly reduced apoptosis during the critical developmental period resulting in elevated numbers of retinal ganglion cells in the adult. Elevated UCP2 levels also protected against excitotoxic cell death induced by intraocular injection of either NMDA or kainic acid. In monolayer cultures of retinal cells, elevated UCP2 levels increased cell survival and rendered the cells independent of the survival-promoting effects of the neurotrophic factors BDNF and CNTF. Taken together, these data implicate UCP2 as an important regulator of retinal neuron survival both during development and in adult animals. PMID:26846222

  19. Retinal Vessel Caliber and Lifelong Neuropsychological Functioning: An Investigative Tool for Cognitive Epidemiology

    PubMed Central

    Shalev, Idan; Moffitt, Terrie E.; Wong, Tien Y.; Meier, Madeline H.; Houts, Renate M.; Ding, Jie; Cheung, Carol YL; Ikram, M. Kamram; Caspi, Avshalom; Poulton, Richie

    2013-01-01

    Why do more intelligent people live healthier and longer lives? One possibility is that intelligence tests assess health of the brain, but psychological science has lacked technology to evaluate this hypothesis. Digital retinal imaging, a new non-invasive method to visualize microcirculation in the eye, may reflect vascular conditions in the brain. We studied the association between retinal vessel caliber and neuropsychological functioning in the representative Dunedin birth cohort. Wider venular caliber was associated with poorer neuropsychological functioning at midlife, independent of potentially confounding factors. This association was not limited to any specific test domain, and extended to informant-reports of cognitive difficulties in everyday life. Moreover, wider venular caliber was associated with lower childhood IQ tested 25 years earlier. The finding indicates that retinal venular caliber may be an indicator of neuropsychological health years before dementing diseases’ onset, and suggests digital retinal imaging as an investigative tool for psychological science. PMID:23678508

  20. Retinal Image Quality During Accommodation

    PubMed Central

    López-Gil, N.; Martin, J.; Liu, T.; Bradley, A.; Díaz-Muñoz, D.; Thibos, L.

    2013-01-01

    Purpose We asked if retinal image quality is maximum during accommodation, or sub-optimal due to accommodative error, when subjects perform an acuity task. Methods Subjects viewed a monochromatic (552nm), high-contrast letter target placed at various viewing distances. Wavefront aberrations of the accommodating eye were measured near the endpoint of an acuity staircase paradigm. Refractive state, defined as the optimum target vergence for maximising retinal image quality, was computed by through-focus wavefront analysis to find the power of the virtual correcting lens that maximizes visual Strehl ratio. Results Despite changes in ocular aberrations and pupil size during binocular viewing, retinal image quality and visual acuity typically remain high for all target vergences. When accommodative errors lead to sub-optimal retinal image quality, acuity and measured image quality both decline. However, the effect of accommodation errors of on visual acuity are mitigated by pupillary constriction associated with accommodation and binocular convergence and also to binocular summation of dissimilar retinal image blur. Under monocular viewing conditions some subjects displayed significant accommodative lag that reduced visual performance, an effect that was exacerbated by pharmacological dilation of the pupil. Conclusions Spurious measurement of accommodative error can be avoided when the image quality metric used to determine refractive state is compatible with the focusing criteria used by the visual system to control accommodation. Real focusing errors of the accommodating eye do not necessarily produce a reliably measurable loss of image quality or clinically significant loss of visual performance, probably because of increased depth-of-focus due to pupil constriction. When retinal image quality is close to maximum achievable (given the eye’s higher-order aberrations), acuity is also near maximum. A combination of accommodative lag, reduced image quality, and reduced

  1. Retinal Optical Coherence Tomography Imaging

    NASA Astrophysics Data System (ADS)

    Drexler, Wolfgang; Fujimoto, James G.

    The eye is essentially transparent, transmitting light with only minimal optical attenuation and scattering providing easy optical access to the anterior segment as well as the retina. For this reason, ophthalmic and especially retinal imaging has been not only the first but also most successful clinical application for optical coherence tomography (OCT). This chapter focuses on the development of OCT technology for retinal imaging. OCT has significantly improved the potential for early diagnosis, understanding of retinal disease pathogenesis, as well as monitoring disease progression and response to therapy. Development of ultrabroad bandwidth light sources and high-speed detection techniques has enabled significant improvements in ophthalmic OCT imaging performance, demonstrating the potential of three-dimensional, ultrahigh-resolution OCT (UHR OCT) to perform noninvasive optical biopsy of the living human retina, i.e., the in vivo visualization of microstructural, intraretinal morphology in situ approaching the resolution of conventional histopathology. Significant improvements in axial resolution and speed not only enable three-dimensional rendering of retinal volumes but also high-definition, two-dimensional tomograms, topographic thickness maps of all major intraretinal layers, as well as volumetric quantification of pathologic intraretinal changes. These advances in OCT technology have also been successfully applied in several animal models of retinal pathologies. The development of light sources emitting at alternative wavelengths, e.g., around #1,060 nm, not only enabled three-dimensional OCT imaging with enhanced choroidal visualization but also improved OCT performance in cataract patients due to reduced scattering losses in this wavelength region. Adaptive optics using deformable mirror technology, with unique high stroke to correct higher-order ocular aberrations, with specially designed optics to compensate chromatic aberration of the human eye, in

  2. New Wrinkles in Retinal Densitometry

    PubMed Central

    Masella, Benjamin D.; Hunter, Jennifer J.; Williams, David R.

    2014-01-01

    Purpose. Retinal densitometry provides objective information about retinal function. But, a number of factors, including retinal reflectance changes that are not directly related to photopigment depletion, complicate its interpretation. We explore these factors and suggest a method to minimize their impact. Methods. An adaptive optics scanning light ophthalmoscope (AOSLO) was used to measure changes in photoreceptor reflectance in monkeys before and after photopigment bleaching with 514-nm light. Reflectance measurements at 514 nm and 794 nm were recorded simultaneously. Several methods of normalization to extract the apparent optical density of the photopigment were compared. Results. We identified stimulus-related fluctuations in 794-nm reflectance that are not associated with photopigment absorptance and occur in both rods and cones. These changes had a magnitude approaching those associated directly with pigment depletion, precluding the use of infrared reflectance for normalization. We used a spatial normalization method instead, which avoided the fluctuations in the near infrared, as well as a confocal AOSLO designed to minimize light from layers other than the receptors. However, these methods produced a surprisingly low estimate of the apparent rhodopsin density (animal 1: 0.073 ± 0.006, animal 2: 0.032 ± 0.003). Conclusions. These results confirm earlier observations that changes in photopigment absorption are not the only source of retinal reflectance change during dark adaptation. It appears that the stray light that has historically reduced the apparent density of cone photopigment in retinal densitometry arises predominantly from layers near the photoreceptors themselves. Despite these complications, this method provides a valuable, objective measure of retinal function. PMID:25316726

  3. 75 FR 62307 - Fire Prevention Week, 2010

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-08

    ... Independence of the United States of America the two hundred and thirty-fifth. (Presidential Sig.) [FR Doc... Documents#0;#0; ] Proclamation 8577 of October 1, 2010 Fire Prevention Week, 2010 By the President of the United States of America A Proclamation During Fire Prevention Week, we reaffirm the importance of...

  4. Retinal Ganglion Cell Adaptation to Small Luminance Fluctuations

    PubMed Central

    Freeman, Daniel K.; Graña, Gilberto

    2010-01-01

    To accommodate the wide input range over which the visual system operates within the narrow output range of spiking neurons, the retina adjusts its sensitivity to the mean light level so that retinal ganglion cells can faithfully signal contrast, or relative deviations from the mean luminance. Given the large operating range of the visual system, the majority of work on luminance adaptation has involved logarithmic changes in light level. We report that luminance gain controls are recruited for remarkably small fluctuations in luminance as well. Using spike recordings from the rat optic tract, we show that ganglion cell responses to a brief flash of light are modulated in amplitude by local background fluctuations as little as 15% contrast. The time scale of the gain control is rapid (<125 ms), at least for on cells. The retinal locus of adaptation precedes the ganglion cell spike generator because response gain changes of on cells were uncorrelated with firing rate. The mechanism seems to reside within the inner retinal network and not in the photoreceptors, because the adaptation profiles of on and off cells differed markedly. The response gain changes follow Weber's law, suggesting that network mechanisms of luminance adaptation described in previous work modulates retinal ganglion cell sensitivity, not just when we move between different lighting environments, but also as our eyes scan a visual scene. Finally, we show that response amplitude is uniformly reduced for flashes on a modulated background that has spatial contrast, indicating that another gain control that integrates luminance signals nonlinearly over space operates within the receptive field center of rat ganglion cells. PMID:20538771

  5. Effects of trkB knockout on topography and ocular segregation of uncrossed retinal projections.

    PubMed

    Rodger, Jennifer; Frost, Douglas O

    2009-05-01

    TrkB is an important receptor for brain-derived neurotrophic factor and NT4, members of the neurotrophin family. TrkB signaling is crucial in many activity-dependent and activity-independent processes of neural development. Here, we investigate the role of trkB signaling in the development of two distinct, organizational features of retinal projections--the segregation of crossed and uncrossed retinal inputs along the "lines of projection" that represent a single point in the visual field and the "retinotopic" mapping of retinofugal axons within their cerebral targets. Using anterograde tracing, we obtained quantitative measures of the distribution of retinal projections in the dorsal nucleus of the lateral geniculate body (LGd) and superior colliculus (SC) of wild-type mice and mice homozygous for constitutive null mutation (knockout) of the full-length trkB receptor (trkB(FL)(-/-)). In trkB(FL)(-/-) mice, uncrossed retinal projections cluster normally but there is a topographic expansion in the distribution of these clusters across the SC. By contrast, the absence of trkB signaling has no significant effect on the segregation of crossed and uncrossed retinal projections along the lines of projection in LGd or SC. We conclude that the normal topographic organization of uncrossed retinal projections depends upon trkB signaling, whereas the segregation of crossed and uncrossed retinal projections is trkB-independent. We also found that in trkB(FL)(-/-) mice, neuronal number was reduced in the LGd and SC and in the caudate-putamen. Previous studies by ourselves and others have shown that the number of retinal ganglion cells (RGCs) is unchanged in trkB(FL)(-/-) mice. Together, these results demonstrate that there is no matching of the numbers of RGCs with neuronal numbers in the LGd or SC. PMID:19283373

  6. Active Fire Mapping Program

    MedlinePlus

    ... Incidents (Home) New Large Incidents Fire Detection Maps MODIS Satellite Imagery VIIRS Satellite Imagery Fire Detection GIS ... Data Web Services Latest Detected Fire Activity Other MODIS Products Frequently Asked Questions About Active Fire Maps ...

  7. ACUTE RETINAL ARTERIAL OCCLUSIVE DISORDERS

    PubMed Central

    Hayreh, Sohan Singh

    2011-01-01

    The initial section deals with basic sciences; among the various topics briefly discussed are the anatomical features of ophthalmic, central retinal and cilioretinal arteries which may play a role in acute retinal arterial ischemic disorders. Crucial information required in the management of central retinal artery occlusion (CRAO) is the length of time the retina can survive following that. An experimental study shows that CRAO for 97 minutes produces no detectable permanent retinal damage but there is a progressive ischemic damage thereafter, and by 4 hours the retina has suffered irreversible damage. In the clinical section, I discuss at length various controversies on acute retinal arterial ischemic disorders. Classification of acute retinal arterial ischemic disorders These are of 4 types: CRAO, branch retinal artery occlusion (BRAO), cotton wools spots and amaurosis fugax. Both CRAO and BRAO further comprise multiple clinical entities. Contrary to the universal belief, pathogenetically, clinically and for management, CRAO is not one clinical entity but 4 distinct clinical entities – non-arteritic CRAO, non-arteritic CRAO with cilioretinal artery sparing, arteritic CRAO associated with giant cell arteritis (GCA) and transient non-arteritic CRAO. Similarly, BRAO comprises permanent BRAO, transient BRAO and cilioretinal artery occlusion (CLRAO), and the latter further consists of 3 distinct clinical entities - non-arteritic CLRAO alone, non-arteritic CLRAO associated with central retinal vein occlusion and arteritic CLRAO associated with GCA. Understanding these classifications is essential to comprehend fully various aspects of these disorders. Central retinal artery occlusion The pathogeneses, clinical features and management of the various types of CRAO are discussed in detail. Contrary to the prevalent belief, spontaneous improvement in both visual acuity and visual fields does occur, mainly during the first 7 days. The incidence of spontaneous visual

  8. Age-dependent homeostatic plasticity of GABAergic signaling in developing retinal networks.

    PubMed

    Hennig, Matthias H; Grady, John; van Coppenhagen, James; Sernagor, Evelyne

    2011-08-24

    Developing retinal ganglion cells fire in correlated spontaneous bursts, resulting in propagating waves with robust spatiotemporal features preserved across development and species. Here we investigate the effects of homeostatic adaptation on the circuits controlling retinal waves. Mouse retinal waves were recorded in vitro for up to 35 h with a multielectrode array in presence of the GABA(A) antagonist bicuculline, allowing us to obtain a precise, time-resolved characterization of homeostatic effects in this preparation. Experiments were performed at P4-P6, when GABA(A) signaling is depolarizing in ganglion cells, and at P7-P10, when GABA(A) signaling is hyperpolarizing. At all ages, bicuculline initially increased the wave sizes and other activity metrics. At P5-P6, wave sizes decreased toward control levels within a few hours while firing remained strong, but this ability to compensate disappeared entirely from P7 onwards. This demonstrates that homeostatic control of spontaneous retinal activity maintains specific network dynamic properties in an age-dependent manner, and suggests that the underlying mechanism is linked to GABA(A) signaling. PMID:21865458

  9. The neural circuit mechanisms underlying the retinal response to motion reversal.

    PubMed

    Chen, Eric Y; Chou, Janice; Park, Jeongsook; Schwartz, Greg; Berry, Michael J

    2014-11-19

    To make up for delays in visual processing, retinal circuitry effectively predicts that a moving object will continue moving in a straight line, allowing retinal ganglion cells to anticipate the object's position. However, a sudden reversal of motion triggers a synchronous burst of firing from a large group of ganglion cells, possibly signaling a violation of the retina's motion prediction. To investigate the neural circuitry underlying this response, we used a combination of multielectrode array and whole-cell patch recordings to measure the responses of individual retinal ganglion cells in the tiger salamander to reversing stimuli. We found that different populations of ganglion cells were responsible for responding to the reversal of different kinds of objects, such as bright versus dark objects. Using pharmacology and designed stimuli, we concluded that ON and OFF bipolar cells both contributed to the reversal response, but that amacrine cells had, at best, a minor role. This allowed us to formulate an adaptive cascade model (ACM), similar to the one previously used to describe ganglion cell responses to motion onset. By incorporating the ON pathway into the ACM, we were able to reproduce the time-varying firing rate of fast OFF ganglion cells for all experimentally tested stimuli. Analysis of the ACM demonstrates that bipolar cell gain control is primarily responsible for generating the synchronized retinal response, as individual bipolar cells require a constant time delay before recovering from gain control. PMID:25411485

  10. Age-dependent Homeostatic Plasticity of GABAergic Signaling in Developing Retinal Networks

    PubMed Central

    Hennig, Matthias H.; Grady, John; van Coppenhagen, James; Sernagor, Evelyne

    2013-01-01

    Developing retinal ganglion cells fire in correlated spontaneous bursts, resulting in propagating waves with robust spatiotemporal features preserved across development and species. Here we investigate the effects of homeostatic adaptation on the circuits controlling retinal waves. Mouse retinal waves were recorded in vitro for up to 35 h with a multielectrode array in presence of the GABAA antagonist bicuculline, allowing us to obtain a precise, time-resolved characterization of homeostatic effects in this preparation. Experiments were performed at P4–P6, when GABAA signaling is depolarizing in ganglion cells, and at P7–P10, when GABAA signaling is hyperpolarizing. At all ages, bicuculline initially increased the wave sizes and other activity metrics. At P5–P6, wave sizes decreased toward control levels within a few hours while firing remained strong, but this ability to compensate disappeared entirely from P7 onwards. This demonstrates that homeostatic control of spontaneous retinal activity maintains specific network dynamic properties in an age-dependent manner, and suggests that the underlying mechanism is linked to GABAA signaling. PMID:21865458

  11. Mechanical Dissociation of Retinal Neurons with Vibration

    NASA Astrophysics Data System (ADS)

    Motomura, Tamami; Hayashida, Yuki; Murayama, Nobuki

    The neuromorphic device, which implements the functions of biological neural circuits by means of VLSI technology, has been collecting much attention in the engineering fields in the last decade. Concurrently, progress in neuroscience research has revealed the nonlinear computation in single neuron levels, suggesting that individual neurons are not merely the circuit elements but computational units. Thus, elucidating the properties of neuronal signal processing is thought to be an essential step for developing the next generation of neuromorphic devices. In the present study, we developed a method for dissociating single neurons from specific sublayers of mammalian retinas with using no proteolytic enzymes but rather combining tissue incubation in a low-Ca2+ medium and the vibro-dissociation technique developed for the slices of brains and spinal cords previously. Our method took shorter time of the procedure, and required less elaborated skill, than the conventional enzymatic method did; nevertheless it yielded enough number of the cells available for acute electrophysiological experiments. The isolated retinal neurons were useful for measuring the nonlinear membrane conductances as well as the spike firing properties under the perforated-patch whole-cell configuration. These neurons also enabled us to examine the effects of proteolytic enzymes on the membrane excitability in those cells.

  12. Are Independent Probes Truly Independent?

    ERIC Educational Resources Information Center

    Camp, Gino; Pecher, Diane; Schmidt, Henk G.; Zeelenberg, Rene

    2009-01-01

    The independent cue technique has been developed to test traditional interference theories against inhibition theories of forgetting. In the present study, the authors tested the critical criterion for the independence of independent cues: Studied cues not presented during test (and unrelated to test cues) should not contribute to the retrieval…

  13. Suppression and retinal correspondence in intermittent exotropia.

    PubMed Central

    Cooper, J; Record, C D

    1986-01-01

    Suppression scotomas and retinal projection (retinal correspondence) were measured in six intermittent exotropes during deviation. Measurements used red-green anaglyph stimuli presented on a black background which could be varied from 3.4 minutes of arc to 3 degrees 24'. Results showed non-suppression of all points between the fovea and the diplopia point. Harmonious anomalous retinal correspondence was usually observed. Two subjects had spontaneous changes from anomalous retinal correspondence to normal retinal correspondence without a concurrent change in ocular position. Conventional testing resulted in more variable results in regard to retinal correspondence and suppression, suggesting that non-suppression and anomalous retinal correspondence occur when black backgrounds are used for testing. PMID:3756124

  14. FIRE BLIGHT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fire blight, caused by the bacterium Erwinia amylovora, is a destructive disease of apple, pears and woody ornamentals of the rose family. The disease is indigenous to North America and has been studied for more than one century. E. amylovora can infect blossoms, stems, immature fruits, woody branch...

  15. Dalhousie Fire

    ERIC Educational Resources Information Center

    Matthews, Fred W.

    1986-01-01

    Describes steps taken by the Weldon Law Library at Dalhousie University in salvaging books damaged in a major fire, including procedures and processes used in packing, sorting, drying, and cleaning the books. The need for a disaster plan for specific libraries is emphasized, and some suggestions are made. (CDD)

  16. Colorado Fires

    Atmospheric Science Data Center

    2014-05-15

    ... (MISR). The images were captured on June 9, 2002, on the second day of the Hayman fire, when only about 13 percent of the total 137,000 ... x 565 kilometers. They use data from blocks 58 to 61 within World Reference System-2 path 32. MISR was built and is managed by NASA's ...

  17. Appalachian Fires

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image of smoke from forest fires in Virginia, Kentucky, and West Virginia was taken by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) on November 15, 2001. Smoke is visible extending over the Chesapeake Bay. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  18. Fire in the Shop!

    ERIC Educational Resources Information Center

    Campbell, Clifton P.; Buchanan, Joseph P.

    1977-01-01

    Fire emergency preparedness measures to take to prevent school fires and to protect against injury and minimize damage when fire does occur are presented. Includes fire safety practices, extinguishers for different classes of fires and their use, and the need for fire safety training in schools. (MF)

  19. 46 CFR 28.315 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... fire pump on a vessel 79 feet (24 meters) or more in length must be capable of delivering water... 46 Shipping 1 2012-10-01 2012-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... After September 15, 1991, and That Operate With More Than 16 Individuals on Board § 28.315 Fire...

  20. 46 CFR 28.315 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... fire pump on a vessel 79 feet (24 meters) or more in length must be capable of delivering water... 46 Shipping 1 2011-10-01 2011-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... After September 15, 1991, and That Operate With More Than 16 Individuals on Board § 28.315 Fire...

  1. Retinitis Pigmentosa and Education Issues

    ERIC Educational Resources Information Center

    Brown, Thomas J.

    2005-01-01

    Retinitis Pigmentosa includes a number of inherited diseases which usually result in blindness. The disease is progressive in nature and begins with the deterioration of cells in the eye responsible for peripheral vision. As the condition worsens there is a gradual loss of peripheral vision and night blindness. Proper educational planning requires…

  2. Identification of Genes and Pathways Involved in Retinal Neovascularization by Microarray Analysis of Two Animal Models of Retinal Angiogenesis

    PubMed Central

    Xu, Lili; Penn, John S.; Boone, Braden; Dexheimer, Phillip J.

    2010-01-01

    Purpose. Comparative retinal gene expression analysis in two rodent models of oxygen-induced retinopathy (OIR) was performed to identify the genes and pathways involved in retinal neovascularization. Methods. Three independent experimental runs were conducted for each species, according to standard protocols for induction of OIR. Total retinal RNA was isolated at two time points, corresponding to the early response to relative hypoxia (P13 in mouse, P15 in rat) and to the later phase of maximum retinal neovascularization (P18 in mouse, P20 in rat) and was used to prepare labeled probes for hybridization. Gene expression was compared between normal and experimental conditions for each species at each time point. Probesets with a false-discovery rate of ≤0.05 were considered significantly different and were classified as cellular functions or biological pathways. Changes in expression of selected genes were confirmed by quantitative rtPCR. Results. At the early time point, there were changes in 43 genes in each species, with two in common. Increased expression of members of the VEGF and ephrin receptor signaling pathways were identified in both models. At the later time point, there were changes in 26 genes in the rat and in 1622 in the mouse, with 13 in common. Four pathways were identified in both models. Conclusions. Genes and pathways known to be involved in angiogenesis, as well as other biologically plausible genes and pathways, were identified. This work serves as a comprehensive resource for the study of retinal neovascularization and identification of potential rational targets for antiangiogenic therapy. PMID:19834031

  3. 3-D segmentation of retinal blood vessels in spectral-domain OCT volumes of the optic nerve head

    NASA Astrophysics Data System (ADS)

    Lee, Kyungmoo; Abràmoff, Michael D.; Niemeijer, Meindert; Garvin, Mona K.; Sonka, Milan

    2010-03-01

    Segmentation of retinal blood vessels can provide important information for detecting and tracking retinal vascular diseases including diabetic retinopathy, arterial hypertension, arteriosclerosis and retinopathy of prematurity (ROP). Many studies on 2-D segmentation of retinal blood vessels from a variety of medical images have been performed. However, 3-D segmentation of retinal blood vessels from spectral-domain optical coherence tomography (OCT) volumes, which is capable of providing geometrically accurate vessel models, to the best of our knowledge, has not been previously studied. The purpose of this study is to develop and evaluate a method that can automatically detect 3-D retinal blood vessels from spectral-domain OCT scans centered on the optic nerve head (ONH). The proposed method utilized a fast multiscale 3-D graph search to segment retinal surfaces as well as a triangular mesh-based 3-D graph search to detect retinal blood vessels. An experiment on 30 ONH-centered OCT scans (15 right eye scans and 15 left eye scans) from 15 subjects was performed, and the mean unsigned error in 3-D of the computer segmentations compared with the independent standard obtained from a retinal specialist was 3.4 +/- 2.5 voxels (0.10 +/- 0.07 mm).

  4. Fire Detection Organizing Questions

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Verified models of fire precursor transport in low and partial gravity: a. Development of models for large-scale transport in reduced gravity. b. Validated CFD simulations of transport of fire precursors. c. Evaluation of the effect of scale on transport and reduced gravity fires. Advanced fire detection system for gaseous and particulate pre-fire and fire signaturesa: a. Quantification of pre-fire pyrolysis products in microgravity. b. Suite of gas and particulate sensors. c. Reduced gravity evaluation of candidate detector technologies. d. Reduced gravity verification of advanced fire detection system. e. Validated database of fire and pre-fire signatures in low and partial gravity.

  5. Activation of retinal tyrosine hydroxylase: tolerance induced by chronic treatment with haloperidol does not modify response to light

    SciTech Connect

    Cohen, J.; Neff, N.H.

    1982-05-01

    A single dose of haloperidol administered to rats in the dark increases the activity of retinal tyrosine hydroxylase. The ability of haloperidol to activate the enzyme is diminished 24 hr after terminating 22 to 30 days of treatment with haloperidol. The retinal enzyme is also tolerant to activation by treatment with chlorpromazine. In contrast, exposure of the animals to light activates the enzyme to the same extent in chronic haloperidol-treated and control animals. Thus, chronic haloperidol treatment does not modify the ability of the retinal enzyme system to respond to the physiological stimulus, light. Apparently, activation of retinol tyrosine hydroxylase by haloperidol and light occurs by independent mechanisms.

  6. Retinal vasculature classification using novel multifractal features

    NASA Astrophysics Data System (ADS)

    Ding, Y.; Ward, W. O. C.; Duan, Jinming; Auer, D. P.; Gowland, Penny; Bai, L.

    2015-11-01

    Retinal blood vessels have been implicated in a large number of diseases including diabetic retinopathy and cardiovascular diseases, which cause damages to retinal blood vessels. The availability of retinal vessel imaging provides an excellent opportunity for monitoring and diagnosis of retinal diseases, and automatic analysis of retinal vessels will help with the processes. However, state of the art vascular analysis methods such as counting the number of branches or measuring the curvature and diameter of individual vessels are unsuitable for the microvasculature. There has been published research using fractal analysis to calculate fractal dimensions of retinal blood vessels, but so far there has been no systematic research extracting discriminant features from retinal vessels for classifications. This paper introduces new methods for feature extraction from multifractal spectra of retinal vessels for classification. Two publicly available retinal vascular image databases are used for the experiments, and the proposed methods have produced accuracies of 85.5% and 77% for classification of healthy and diabetic retinal vasculatures. Experiments show that classification with multiple fractal features produces better rates compared with methods using a single fractal dimension value. In addition to this, experiments also show that classification accuracy can be affected by the accuracy of vessel segmentation algorithms.

  7. Oregon Fires

    Atmospheric Science Data Center

    2014-05-15

    article title:  Smoke Plumes from the B&B Complex Fires, Oregon     ... The results indicate that the tops of the two main plumes originating from the B&B complex differ in altitude by about 1-2 ... The  animation  depicts a "multi-angle fly-over" of the plumes, and was generated using red-band data from MISR's vertical and ...

  8. Associations between Depression and Anxiety Symptoms with Retinal Vessel Caliber in Adolescents and Young Adults

    PubMed Central

    Meier, Madeline H.; Gillespie, Nathan A.; Hansell, Narelle K.; Hewitt, Alex W.; Hickie, Ian B.; Lu, Yi; MacGregor, Stuart; Medland, Sarah E.; Sun, Cong; Wong, Tien Y.; Wright, Margie; Zhu, Gu; Martin, Nicholas G.; Mackey, David A.

    2014-01-01

    Objective Previous longitudinal studies suggest that depression and anxiety are associated with risk for cardiovascular disease. The aim of the present study was to test whether an association between depression and anxiety symptoms and retinal vessel caliber, an indicator of subclinical cardiovascular risk, is apparent as early as adolescence and young adulthood. Methods Participants were 865 adolescents and young adults who participated in the Brisbane Longitudinal Twin Study and the Twin Eye Study in Tasmania. Participants completed the Somatic and Psychological Health Report (SPHERE), including assessments of depression/anxiety and somatic symptom subscales, when they were M=16.5 years, and they underwent retinal imaging M=2.5 years later (range=2 years before to 7 years after the depression/anxiety assessment). Retinal vessel caliber was assessed using computer software. Results: Depression and anxiety symptoms were associated with wider retinal arteriolar caliber in this sample of adolescents and young adults (β=0.09, p=.016), even after adjusting for other cardiovascular risk factors (β=0.08, p=.025). Multiple regression analyses revealed that affective symptoms of depression/anxiety were associated with retinal vessel caliber independently of somatic symptoms. Conclusions Depression and anxiety symptoms are associated with measurable signs in the retinal microvasculature in early life, suggesting that pathological microvascular mechanisms may be operative in the association between depression and anxiety with cardiovascular disease starting as early as adolescence. PMID:25373892

  9. Constitutive Overexpression of Human Erythropoietin Protects the Mouse Retina against Induced But Not Inherited Retinal Degeneration

    PubMed Central

    Grimm, Christian; Wenzel, Andreas; Stanescu, Dinu; Samardzija, Marijana; Hotop, Svenja; Groszer, Mathias; Naash, Muna; Gassmann, Max; Remé, Charlotte

    2010-01-01

    Elevation of erythropoietin (Epo) concentrations by hypoxic preconditioning or application of recombinant human Epo (huEpo) protects the mouse retina against light-induced degeneration by inhibiting photoreceptor cell apoptosis. Because photoreceptor apoptosis is also the common path to cell loss in retinal dystrophies such as retinitis pigmentosa (RP), we tested whether high levels of huEpo would reduce apoptotic cell death in two mouse models of human RP. We combined the two respective mutant mouse lines with a transgenic line (tg6) that constitutively overexpresses huEpo mainly in neural tissues. Transgenic expression of huEpo caused constitutively high levels of Epo in the retina and protected photoreceptors against light-induced degeneration; however, the presence of high levels of huEpo did not affect the course or the extent of retinal degeneration in a light-independent (rd1) and a light-accelerated (VPP) mouse model of RP. Similarly, repetitive intraperitoneal injections of recombinant huEpo did not protect the retina in the rd1 and the VPP mouse. Lack of neuroprotection by Epo in the two models of inherited retinal degeneration was not caused by adaptational downregulation of Epo receptor. Our results suggest that apoptotic mechanisms during acute, light-induced photoreceptor cell death differ from those in genetically based retinal degeneration. Therapeutic intervention with cell death in inherited retinal degeneration may therefore require different drugs and treatments. PMID:15215287

  10. Adaptive optics imaging of the outer retinal tubules in Bietti's crystalline dystrophy.

    PubMed

    Battu, R; Akkali, M C; Bhanushali, D; Srinivasan, P; Shetty, R; Berendschot, T T J M; Schouten, J S A G; Webers, C A

    2016-05-01

    PurposeTo study the outer retinal tubules using spectral domain optical coherence tomography and adaptive optics and in patients with Bietti's crystalline dystrophy.MethodsTen eyes of five subjects from five independent families with Bietti's crystalline Dystrophy (BCD) were characterized with best-corrected visual acuity (BCVA), full-field electroretinography, and fundus autofluorescence (FAF). High-resolution images were obtained with the spectral domain optical coherence tomography (SD-OCT) and adaptive optics (AO).ResultsSD-OCT showed prominent outer retinal layer loss and outer retinal tubulations at the margin of outer retinal loss. AO images displayed prominent macrotubules and microtubules with characteristic features in eight out of the 10 eyes. Crystals were present in all ten eyes. There was a reduction in the cone count in all eyes in the area outside the outer retinal tubules (ORT).ConclusionsThis study describes the morphology of the outer retinal tubules when imaged enface on the adaptive optics in patients with BCD. These findings provide insight into the macular structure of these patients. This may have prognostic implications and refine the study on the pathogenesis of BCD. PMID:26915747

  11. Automated detection of the retinal from OCT spectral domain images of healthy eyes

    NASA Astrophysics Data System (ADS)

    Giovinco, Gaspare; Savastano, Maria Cristina; Ventre, Salvatore; Tamburrino, Antonello

    2015-06-01

    Optical coherence tomography (OCT) has become one of the most relevant diagnostic tools for retinal diseases. Besides being a non-invasive technique, one distinguished feature is its unique capability of providing (in vivo) cross-sectional view of the retinal. Specifically, OCT images show the retinal layers. From the clinical point of view, the identification of the retinal layers opens new perspectives to study the correlation between morphological and functional aspects of the retinal tissue. The main contribution of this paper is a new method/algorithm for the automated segmentation of cross-sectional images of the retina of healthy eyes, obtained by means of spectral domain optical coherence tomography (SD-OCT). Specifically, the proposed segmentation algorithm provides the automated detection of different retinal layers. Tests on experimental SD-OCT scans performed by three different instruments/manufacturers have been successfully carried out and compared to a manual segmentation made by an independent ophthalmologist, showing the generality and the effectiveness of the proposed method.

  12. Role of retinal metabolism in methanol-induced retinal toxicity

    SciTech Connect

    Garner, C.D. |; Lee, E.W.; Terzo, T.S.; Louis-Ferdinand, R.T.

    1995-08-01

    Methanol is a toxicant that causes systemic and ocular toxicity after acute exposure. The folate-reduced (FR) rat is an excellent animal model that mimics characteristic human methanol toxic responses. The present study examines the role of the methanol metabolites formaldehyde and formate in the initiation of methanol-induced retinal toxicity. After a single oral dose of 3.0 g/kg methanol, blood methanol concentrations were not significantly different in FR rats compared with folate-sufficient (FS) (control) rats. However, FR rats treated with 3.0 g/kg methanol displayed elevated blood (14.6 mM) and vitreous humor (19.5 mM) formate levels and abnormal electroretinograms (loss of b-wave) 48 h postdose. FR rats pretreated with disulfiram (DSF) prior to 3.0 g/kg methanol treatment failed to display these symptoms. Formaldehyde was not detected in blood or vitreous humor with or without DSF treatment, suggesting that formate is the toxic metabolite in methanol-induced retinal toxicity. Additionally, creating a blood formate profile (14.2 mM at 48 h) similar to that observed in methanol-treated rats by iv infusion of pH-buffered formate does not alter the electroretinogram as is observed with methanol treatment. These data suggest that intraretinal metabolism of methanol is necessary for the formate-mediated initiation of methanol-induced retinal toxicity. 31 refs., 5 figs., 2 tabs.

  13. Zaca Fire

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On August 7, 2007, the Zaca fire continued to burn in the Los Padres National Forest near Santa Barbara, California. The fire started more than a month ago, on July 4, and has burned 69,800 acres. The fire remains in steep, rocky terrain with poor access. The continued poor access makes containment difficult in the wilderness area on the eastern flank. So far only one outbuilding has been destroyed; but over 450 homes are currently threatened. Over 2300 fire personnel, aided by four air tankers and 15 helicopters, are working to contain this massive fire. Full containment is expected on September 1.

    The image covers 45.2 x 46.1 km, and is centered near 34.6 degrees north latitude, 119.7 degrees west longitude.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra spacecraft. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission

  14. On the retinal toxicity of intraocular glucocorticoids.

    PubMed

    Torriglia, Alicia; Valamanesh, Fatemeh; Behar-Cohen, Francine

    2010-12-15

    Corticosteroids are hormones involved in many physiological responses such as stress, immune modulation, protein catabolism and water homeostasis. The subfamily of glucocorticoids is used systemically in the treatment of inflammatory diseases or allergic reactions. In the eye, glucocorticoides are used to treat macular edema, inflammation and neovascularization. The most commonly used glucocorticoid is triamcinolone acetonide (TA). The pharmaceutical formulation of TA is not adapted for intravitreal administration but has been selected by ophthalmologists because its very low intraocular solubility provides sustained effect. Visual benefits of intraocular TA do not clearly correlate with morpho-anatomical improvements, suggesting potential toxicity. We therefore studied, non-common, but deleterious effects of glucocorticoids on the retina. We found that the intravitreal administration of TA is beneficial in the treatment of neovascularization because it triggers cell death of endothelial cells of neovessels by a caspase-independent mechanism. However, this treatment is toxic for the retina because it induces a non-apoptotic, caspase-independent cell death related to paraptosis, mostly in the retinal pigmented epithelium cells and the Müller cells. PMID:20654583

  15. Association between Retinal Arteriolar and Venule Calibre with Prevalent Heart Failure: A Cross-Sectional Study

    PubMed Central

    Phan, Kevin; Mitchell, Paul; Liew, Gerald; Plant, Adam J.; Wang, Sarah B.; Au, Cheryl; Chiha, Joseph; Kovoor, Pramesh; Thiagalingam, Aravinda; Burlutsky, George; Gopinath, Bamini

    2015-01-01

    Background There is evidence to suggest that microvascular disease, particularly diabetic retinopathy, plays a role in the pathogenesis of HF. However, whether changes in retinal vessel calibre predicts HF is unclear. The purpose of this study was to examine the association of retinal microvascular structure with prevalent heart failure (HF). Methods The Australian Heart Eye Study (AHES) is a cross-sectional study that surveyed 1680 participants who presented to a tertiary referral hospital for the evaluation of potential coronary artery disease by coronary angiography. Retinal vessel calibre was graded using retinal photography and participants’ self-reported echocardiography-confirmed HF was obtained via an extensive medical questionnaire. Results There were 107 participants (8.1%) with prevalent self-reported HF. Persons with wider retinal arteriolar calibre (comparing highest versus lowest tertile or reference) were more likely to have prevalent HF (OR 3.5; 95% CI, 1.7–7.2) when adjusted for age and sex. After further adjustment for body mass index, hypertension, diabetes, smoking status, triglycerides and estimated glomerular filtration rate, this association remained significant (OR 4.5; 95% CI, 2.0–9.8). After further stratification, this association remained significant among participants with diabetes (OR 10.3; 95% CI, 2.7–39.3) but not in those without diabetes (OR 2.7; 95% CI, 0.9–7.5). The strength of this association was not dependent on the length of history of diabetes, or retinopathy status. There was no significant association between retinal venular calibre and prevalence of HF. Conclusions Wider retinal arteriolar diameter was significantly and independently associated with prevalent HF in participants of a cross-sectional study. This association was significant stronger among participants with diabetes compared to without diabetes. No association was found between retinal venule calibre with prevalent HF. PMID:26659133

  16. Role of retinal vascular endothelial cells in development of CMV retinitis.

    PubMed Central

    Rao, N A; Zhang, J; Ishimoto, S

    1998-01-01

    PURPOSE: Although cytomegalovirus (CMV) retinitis is known to occur in association with retinal microangiopathy in individuals with marked immunodeficiency, glial cells are believed to be the initial target cells in the development of retinitis. Moreover, it has been hypothesized that CMV gains access to the retinal glia because of altered vascular permeability. In an attempt to address the hypothesis, we studied 30 autopsy eyes of AIDS patients with systemic CMV infection, with or without clinically apparent CMV retinitis. METHODS: The autopsy eyes were processed in three ways. First, dual immunohistochemical studies were done by using anti-CMV antibodies for immediate early, early, and late antigens. The retinal cell types infected with the virus were then determined by using anti-GFAP, anti-VonWillebrand's factor, neuronal specific enolase, and leukocyte marker CD68. Second, selected eyes were processed for in situ hybridization with DNA probe specific to CMV. Third, an eye with clinically apparent CMV retinitis was submitted for electron microscopic examination. RESULTS: At the site of retinal necrosis in those eyes with a clinical diagnosis of CMV retinitis, the immunohistochemical, in situ hybridization, and ultrastructural examinations revealed that CMV was present primarily in the Müller cells and in perivascular glial cells. Adjacent to these infected cells, focal areas of positive staining for CMV antigen were seen in the glial cells, neuronal cells, and retinal pigment epithelial cells. At these sites most of the retinal capillaries were devoid of endothelial cells. Few vessels located at the advancing margin of retinal necrosis showed the presence of viral proteins in the endothelial cells. CONCLUSIONS: The present results indicate that retinal vascular endothelial cells could be the initial target in the development of viral retinitis, with subsequent spread of the infection to perivascular glia, Müller cells, and other retinal cells, including the

  17. Current perspectives of herpesviral retinitis and choroiditis.

    PubMed

    Madhavan, H N; Priya, K; Biswas, J

    2004-10-01

    Vision-threatening viral retinitis are primarily caused by members of the herpesvirus family. The biology and molecular characterization of herpesviruses, clinical presentations of retinopathies, pathology and pathogenesis including the host responses, epidemiology and the laboratory methods of aetiological diagnosis of these diseases are described. Clinical syndromes are acute retinal necrosis (ARN), progressive outer retinal necrosis (PORN), cytomegalovirus (CMV) retinitis, multifocal choroiditis and serpiginous choroiditis besides other viral retinopathies. Herpes simplex virus (HSV) retinitis is more common in immunocompetent persons while varicella zoster virus (VZV) affects both immunocompetent and immunosuppressed patients equally. CMV retinitis is most common among patients with AIDS. The currently employed laboratory methods of antigen detection, virus isolation and antibody detection by enzyme linked immuno-sorbent assay (ELISA) have low sensitivity. Polymerase chain reaction (PCR) has increased the value of diagnosis due to its high clinical sensitivity and absolute specificity in detection of herpesviruses in intraocular specimens. PMID:16295367

  18. Retinal abnormalities in β-thalassemia major.

    PubMed

    Bhoiwala, Devang L; Dunaief, Joshua L

    2016-01-01

    Patients with beta (β)-thalassemia (β-TM: β-thalassemia major, β-TI: β-thalassemia intermedia) have a variety of complications that may affect all organs, including the eye. Ocular abnormalities include retinal pigment epithelial degeneration, angioid streaks, venous tortuosity, night blindness, visual field defects, decreased visual acuity, color vision abnormalities, and acute visual loss. Patients with β-thalassemia major are transfusion dependent and require iron chelation therapy to survive. Retinal degeneration may result from either retinal iron accumulation from transfusion-induced iron overload or retinal toxicity induced by iron chelation therapy. Some who were never treated with iron chelation therapy exhibited retinopathy, and others receiving iron chelation therapy had chelator-induced retinopathy. We will focus on retinal abnormalities present in individuals with β-thalassemia major viewed in light of new findings on the mechanisms and manifestations of retinal iron toxicity. PMID:26325202

  19. Fire suppressing apparatus. [sodium fires

    DOEpatents

    Buttrey, K.E.

    1980-12-19

    Apparatus for smothering a liquid sodium fire comprises a pan, a perforated cover on the pan, and tubed depending from the cover and providing communication between the interior of the pan and the ambient atmosphere through the perforations in the cover. Liquid caught in the pan rises above the lower ends of the tubes and thus serves as a barrier which limits the amount of air entering the pan.

  20. Salam's independence

    NASA Astrophysics Data System (ADS)

    Fraser, Gordon

    2009-01-01

    In his kind review of my biography of the Nobel laureate Abdus Salam (December 2008 pp45-46), John W Moffat wrongly claims that Salam had "independently thought of the idea of parity violation in weak interactions".

  1. Gene Therapy for Retinal Diseases

    PubMed Central

    Samiy, Nasrollah

    2014-01-01

    Gene therapy has a growing research potential particularly in the field of ophthalmic and retinal diseases owing to three main characteristics of the eye; accessibility in terms of injections and surgical interventions, its immune-privileged status facilitating the accommodation to the antigenicity of a viral vector, and tight blood-ocular barriers which save other organs from unwanted contamination. Gene therapy has tremendous potential for different ocular diseases. In fact, the perspective of gene therapy in the field of eye research does not confine to exclusive monogenic ophthalmic problems and it has the potential to include gene based pharmacotherapies for non-monogenic problems such as age related macular disease and diabetic retinopathy. The present article has focused on how gene transfer into the eye has been developed and used to treat retinal disorders with no available therapy at present. PMID:25709778

  2. Retinitis pigmentosa in southern Africa.

    PubMed

    Greenberg, J; Bartmann, L; Ramesar, R; Beighton, P

    1993-11-01

    Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal disorders which are a common cause of genetic blindness. The relative frequencies of the different forms of RP in South Africa, as determined from the register at the DNA banking centre for RP at the Department of Human Genetics, University of Cape Town, are presented and discussed. Of the 125 families analysed, 29 (23%) showed autosomal dominant, 33 (27%) autosomal recessive and 3 (3%) X-linked inheritance. In 10 families the pedigree data were insufficient to allow accurate genetic subtyping and a further 50 patients were sporadic without a family history of RP or other syndromic features which would allow categorization. PMID:8313621

  3. Retinal vein occlusion: current treatment.

    PubMed

    Lattanzio, Rosangela; Torres Gimeno, Ana; Battaglia Parodi, Maurizio; Bandello, Francesco

    2011-01-01

    Retinal vein occlusion (RVO) is a pathology noted for more than 150 years. Although a lot has been written on the matter, it is still a frequent condition with multifactorial etiopathogenesis with many unclear aspects. The RVO pathogenesis has varied systemic and local implications that make it difficult to elaborate treatment guidelines. The management of the patient with RVO is very complex and a multidisciplinary approach is required in order to identify and correct the associated risk factors. Laser therapy remains the gold standard in RVO, but only modest functional improvement has been shown in branch retinal occlusion forms. Multicenter studies of intravitreal drugs present them as an option to combine with laser. Anti-vascular endothelial growth factor, corticosteroids and sustained-release implants are the future weapons to stop disease progression and get a better visual outcome. Consequently, it is useful to clarify some aspects of the pathology that allow a better patient management. PMID:20938213

  4. Operational challenges of retinal prostheses.

    PubMed

    Schmid, Erich W; Fink, Wolfgang; Wilke, Robert

    2014-12-01

    Two computational models for research on retinal implants are presented. In the first model, the electric field produced by a multi-electrode array in a uniform retina is calculated. It is shown how cross talk of activated electrodes and the resulting bunching of field lines in monopole and dipole activation prevent high resolution imaging with retinal implants. Furthermore, it is demonstrated how sequential stimulation and multipolar stimulation may overcome this limitation. In the second model a target volume, i.e., a probe cylinder approximating a bipolar cell, in the retina is chosen, and the passive Heaviside cable equation is solved inside this target volume to calculate the depolarization of the cell membrane. The depolarization as a function of time indicates that shorter signals stimulate better as long as the current does not change sign during stimulation of the retina, i.e., mono-phasic stimulation. Both computational models are equally applicable to epiretinal, subretinal, and suprachoroidal vision implants. PMID:25443535

  5. Acquired retinal folds in the cat.

    PubMed

    MacMillan, A D

    1976-06-01

    Retinal folds were found in 5 cats. The apparent cause of the folding was varied: in 1 cat the folds appeared after a localized retinal detachment; in 2 cats the condition accompanied other intraocular abnormalities associated with feline infectious peritonitis; 1 cat had active keratitis, and the retinal changes were thought to have been injury related; and 1 cat, bilaterally affected, had chronic glomerulonephritis. PMID:945253

  6. Angiographic results of retinal-retinal anastomosis and retinal-choroidal anastomosis after treatments in eyes with retinal angiomatous proliferation

    PubMed Central

    Saito, Masaaki; Iida, Tomohiro; Kano, Mariko; Itagaki, Kanako

    2012-01-01

    Background The purpose of this study was to evaluate the angiographic results of retinal-retinal anastomosis (RRA) and retinal-choroidal anastomosis (RCA) for eyes with retinal angiomatous proliferation (RAP) after treatment with intravitreal bevacizumab injections as monotherapy or intravitreal bevacizumab combined with photodynamic therapy. Methods In this interventional, consecutive case series, we retrospectively reviewed five naïve eyes from four patients (mean age 80 years) treated with three consecutive monthly intravitreal bevacizumab (1.25 mg/0.05 mL) injections as initial treatment, and followed up for at least 3 months. In cases with over 3 months of follow-up and having recurrence of RAP or leakage by fluorescein angiography, retreatment was performed with a single intravitreal bevacizumab injection and photodynamic therapy. Results Indocyanine green angiography showed RRA in three eyes with subretinal neovascularization and RCA in two eyes with choroidal neovascularization at baseline. At 3 months after baseline (month 3), neither the RRA nor RCA was occluded in any eye on indocyanine green angiography. Retreatment with intravitreal bevacizumab plus photodynamic therapy was performed in three eyes at months 3 (persistent leakage on fluorescein angiography), 6, and 7 (recurrence of RAP lesion), which achieved obvious occlusion of the RRA and RCA. Mean best-corrected visual acuity improved from 0.13 to 0.21 at month 3 (P = 0.066). No complications or systemic adverse events were noted. Conclusion Although intravitreal bevacizumab for RAP was effective in improving visual acuity during short-term follow-up, intravitreal bevacizumab could not achieve complete occlusion of RRA and RCA, which could lead to recurrence of a RAP lesion and exudation. Retreatment with intravitreal bevacizumab plus photodynamic therapy ultimately achieved complete occlusion of the RRA and RCA. PMID:22969283

  7. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps-T/ALL. 34.10-5 Section 34.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Fire Main System, Details § 34.10-5 Fire pumps—T/ALL. (a) Tankships shall be equipped with independently driven fire pumps...

  8. Fire Safety Training Handbook.

    ERIC Educational Resources Information Center

    Montgomery County Dept. of Fire and Rescue Services, Rockville, MD. Div. of Fire Prevention.

    Designed for a community fire education effort, particularly in which local volunteers present general information on fire safety to their fellow citizens, this workbook contains nine lessons. Included are an overview of the household fire problem; instruction in basic chemistry and physics of fire, flammable liquids, portable fire extinguishers,…

  9. Fire Protection for Buildings

    ERIC Educational Resources Information Center

    Edmunds, Jane

    1972-01-01

    Reviews attack on fire safety in high rise buildings made by a group of experts representing the iron and steel industry at a recent conference. According to one expert, fire problems are people oriented, which calls for emphasis on fire prevention rather than reliance on fire suppression and for fire pretection to be built into a structure.…

  10. FIRE ALARM SYSTEM OUTDATED.

    ERIC Educational Resources Information Center

    CHANDLER, L.T.

    AN EFFICIENT FIRE ALARM SYSTEM SHOULD--(1) PROVIDE WARNING OF FIRES THAT START IN HIDDEN OR UNOCCUPIED LOCATIONS, (2) INDICATE WHERE THE FIRE IS, (3) GIVE ADVANCE WARNING TO FACULTY AND ADMINISTRATION SO THAT PANIC AND CONFUSION CAN BE AVOIDED AND ORDERLY EVACUATION OCCUR, (4) AUTOMATICALLY NOTIFY CITY FIRE HEADQUARTERS OF THE FIRE, (5) OPERATE BY…

  11. 46 CFR 28.315 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... After September 15, 1991, and That Operate With More Than 16 Individuals on Board § 28.315 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel 36 feet (11.8 meters) or more in length must... fire pump on a vessel 79 feet (24 meters) or more in length must be capable of delivering...

  12. 46 CFR 28.315 - Fire pumps, fire mains, fire hydrants, and fire hoses.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... After September 15, 1991, and That Operate With More Than 16 Individuals on Board § 28.315 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel 36 feet (11.8 meters) or more in length must... fire pump on a vessel 79 feet (24 meters) or more in length must be capable of delivering...

  13. Retinal pathways influence temporal niche

    PubMed Central

    Doyle, Susan E.; Yoshikawa, Tomoko; Hillson, Holly; Menaker, Michael

    2008-01-01

    In mammals, light input from the retina entrains central circadian oscillators located in the suprachiasmatic nuclei (SCN). The phase of circadian activity rhythms with respect to the external light:dark cycle is reversed in diurnal and nocturnal species, although the phase of SCN rhythms relative to the light cycle remains unchanged. Neural mechanisms downstream from the SCN are therefore believed to determine diurnality or nocturnality. Here, we report a switch from nocturnal to diurnal entrainment of circadian activity rhythms in double-knockout mice lacking the inner-retinal photopigment melanopsin (OPN4) and RPE65, a key protein used in retinal chromophore recycling. These mice retained only a small amount of rod function. The change in entrainment phase of Rpe65−/−;Opn4−/− mice was accompanied by a reversal of the rhythm of clock gene expression in the SCN and a reversal in acute masking effects of both light and darkness on activity, suggesting that the nocturnal to diurnal switch is due to a change in the neural response to light upstream from the SCN. A switch from nocturnal to diurnal activity rhythms was also found in wild-type mice transferred from standard intensity light:dark cycles to light:dark cycles in which the intensity of the light phase was reduced to scotopic levels. These results reveal a novel mechanism by which changes in retinal input can mediate acute temporal-niche switching. PMID:18695249

  14. Retinal Cell Degeneration in Animal Models

    PubMed Central

    Niwa, Masayuki; Aoki, Hitomi; Hirata, Akihiro; Tomita, Hiroyuki; Green, Paul G.; Hara, Akira

    2016-01-01

    The aim of this review is to provide an overview of various retinal cell degeneration models in animal induced by chemicals (N-methyl-d-aspartate- and CoCl2-induced), autoimmune (experimental autoimmune encephalomyelitis), mechanical stress (optic nerve crush-induced, light-induced) and ischemia (transient retinal ischemia-induced). The target regions, pathology and proposed mechanism of each model are described in a comparative fashion. Animal models of retinal cell degeneration provide insight into the underlying mechanisms of the disease, and will facilitate the development of novel effective therapeutic drugs to treat retinal cell damage. PMID:26784179

  15. Retinal Effects Of Blue Light Exposure

    NASA Astrophysics Data System (ADS)

    Ham, William T.; Mueller, Harold A.; Ruffolo, J. J.

    1980-10-01

    Recent research has shown that blue light exposure is an important factor in certain types of retinal injury. The mammalian ocular media transmits the spectral band 400-1400 nm to the retina. The short wavelengths (400-550 nm) produce a photochemical or actinic type of damage, while the longer wavelengths (550-1400 nm) produce thermal damage. Distinction between the two types of retinal damage are discussed briefly and the importance of the blue light effect for solar retinitis and eclipse blindness is emphasized. The significance of blue light retinal injury is summarized for various environmental and occupational exposures.

  16. Retinal Macroglial Responses in Health and Disease

    PubMed Central

    de Hoz, Rosa; Rojas, Blanca; Ramírez, Ana I.; Salazar, Juan J.; Gallego, Beatriz I.; Triviño, Alberto; Ramírez, José M.

    2016-01-01

    Due to their permanent and close proximity to neurons, glial cells perform essential tasks for the normal physiology of the retina. Astrocytes and Müller cells (retinal macroglia) provide physical support to neurons and supplement them with several metabolites and growth factors. Macroglia are involved in maintaining the homeostasis of extracellular ions and neurotransmitters, are essential for information processing in neural circuits, participate in retinal glucose metabolism and in removing metabolic waste products, regulate local blood flow, induce the blood-retinal barrier (BRB), play fundamental roles in local immune response, and protect neurons from oxidative damage. In response to polyetiological insults, glia cells react with a process called reactive gliosis, seeking to maintain retinal homeostasis. When malfunctioning, macroglial cells can become primary pathogenic elements. A reactive gliosis has been described in different retinal pathologies, including age-related macular degeneration (AMD), diabetes, glaucoma, retinal detachment, or retinitis pigmentosa. A better understanding of the dual, neuroprotective, or cytotoxic effect of macroglial involvement in retinal pathologies would help in treating the physiopathology of these diseases. The extensive participation of the macroglia in retinal diseases points to these cells as innovative targets for new drug therapies. PMID:27294114

  17. Retinal detachment associated with atopic dermatitis.

    PubMed Central

    Takahashi, M; Suzuma, K; Inaba, I; Ogura, Y; Yoneda, K; Okamoto, H

    1996-01-01

    BACKGROUND: Retinal detachment associated with atopic dermatitis, one of the most common forms of dermatitis in Japan, has markedly increased in Japan in the past 10 years. To clarify pathogenic mechanisms of retinal detachment in such cases, we retrospectively studied clinical characteristics of retinal detachment associated with atopic dermatitis. METHODS: We examined the records of 80 patients (89 eyes) who had retinal detachment associated with atopic dermatitis. The patients were classified into three groups according to lens status: group A, eyes with clear lenses (40 eyes); group B, eyes with cataract (38 eyes), and group C, aphakic or pseudophakic eyes (11 eyes). RESULTS: No significant differences were noted in the ratio of males to females, age distribution, refractive error, or characteristic of retinal detachment among the three groups. The types of retinal breaks, however, were different in eyes with and without lens changes. While atrophic holes were dominant in group A, retinal dialysis was mainly seen in groups B and C. CONCLUSION: These findings suggested that anterior vitreoretinal traction may play an important role in the pathogenesis of retinal breaks in eyes with atopic cataract and that the same pathological process may affect the formation of cataract and tractional retinal breaks in patients with atopic dermatitis. PMID:8664234

  18. Retinal damage induced by commercial light emitting diodes (LEDs).

    PubMed

    Jaadane, Imene; Boulenguez, Pierre; Chahory, Sabine; Carré, Samuel; Savoldelli, Michèle; Jonet, Laurent; Behar-Cohen, Francine; Martinsons, Christophe; Torriglia, Alicia

    2015-07-01

    Spectra of "white LEDs" are characterized by an intense emission in the blue region of the visible spectrum, absent in daylight spectra. This blue component and the high intensity of emission are the main sources of concern about the health risks of LEDs with respect to their toxicity to the eye and the retina. The aim of our study was to elucidate the role of blue light from LEDs in retinal damage. Commercially available white LEDs and four different blue LEDs (507, 473, 467, and 449nm) were used for exposure experiments on Wistar rats. Immunohistochemical stain, transmission electron microscopy, and Western blot were used to exam the retinas. We evaluated LED-induced retinal cell damage by studying oxidative stress, stress response pathways, and the identification of cell death pathways. LED light caused a state of suffering of the retina with oxidative damage and retinal injury. We observed a loss of photoreceptors and the activation of caspase-independent apoptosis, necroptosis, and necrosis. A wavelength dependence of the effects was observed. Phototoxicity of LEDs on the retina is characterized by a strong damage of photoreceptors and by the induction of necrosis. PMID:25863264

  19. The role of early neural activity in the maturation of turtle retinal function.

    PubMed

    Sernagor, E; Mehta, V

    2001-10-01

    In the developing vertebrate retina, ganglion cells fire spontaneous bursts of action potentials long before the eye becomes exposed to sensory experience at birth. These early bursts are synchronised between neighbouring retinal ganglion cells (RGCs), yielding unique spatiotemporal patterns: 'waves' of activity sweep across large retinal areas every few minutes. Both at retinal and extraretinal levels, these embryonic retinal waves are believed to guide the wiring of the visual system using hebbian mechanisms of synaptic strengthening. In the first part of this review, we recapitulate the evidence for a role of these embryonic spontaneous bursts of activity in shaping developing complex receptive field properties of RGCs in the turtle embryonic retina. We also discuss the role of visual experience in establishing RGC visual functions, and how spontaneous activity and visual experience interact to bring developing receptive fields to maturation. We have hypothesised that the physiological changes associated with development reflect modifications in the dendritic arbours of RGCs, the anatomical substrate of their receptive fields. We demonstrate that there is a temporal correlation between the period of receptive field expansion and that of dendritic growth. Moreover, the immature spontaneous activity contributes to dendritic growth in developing RGCs. Intracellular staining of RGCs reveals, however, that immature receptive fields only rarely show direct correlation with the layout of the corresponding dendritic tree. To investigate the possibility that not only the presence of the spontaneous activity, but even the precise spatiotemporal patterns encoded in retinal waves might contribute to the refinement of retinal neural circuitry, first we must clarify the mechanisms mediating the generation and propagation of these waves across development. In the second part of this review, we present evidence that turtle retinal waves, visualised using calcium imaging

  20. Home Fires Involving Grills

    MedlinePlus

    ... fires were fueled by gas while 13% used charcoal or other solid fuel. Gas grills were involved ... structure fires and 4,300 outdoor fires annually. Charcoal or other solid-fueled grills were involved in ...

  1. Fire safety at home

    MedlinePlus

    ... over the smoke alarm as needed. Using a fire extinguisher can put out a small fire to keep it from getting out of control. Tips for use include: Keep fire extinguishers in handy locations, at least one on ...

  2. Home Fires Involving Grills

    MedlinePlus

    ... per year, including an average of 3,900 structure fires and 5,100 outside fires. These 8, ... property damage.  Almost all the losses resulted from structure fires.  July was the peak month for grill ...

  3. Risk factors of rhegmatogenous retinal detachment associated with choroidal detachment in Chinese patients

    PubMed Central

    Gu, Yong-Hao; Ke, Gen-Jie; Wang, Lin; Gu, Qi-Hong; Zhou, En-Liang; Pan, Hong-Biao; Wang, Shi-Ying

    2016-01-01

    AIM To comprehensively analyze the risk factors of rhegmatogenous retinal detachment (RRD) associated with choroidal detachment (CD). METHODS A total of 265 eyes of 265 consecutive cases of RRD were retrospectively analyzed. All patients had systemic and ophthalmologic examination. CD was diagnosed by indirect ophthalmoscopy, B-scan ultrasonography, and ultrasound biomicroscope (UBM). Each parameter was compared between patients of RRD and rhegmatogenous retinal detachment associated with choroidal detachment (RRDCD). Logistic regression analysis was used to determine the independent risk factors of CD. RESULTS There were 52 eyes (19.62%) with CD. Pseudophakia was more commonly seen in RRDCD (21.15% vs 6.10%, P=0.002). Intraocular pressure (IOP) was lower (8.60±3.62 vs 12.96±3.55, P<0.001), best-corrected visual acuity was worse [3.00 (2.00 to 3.00) vs 1.92 (1.22 to 3.00), P=0.001], and refractive error was more myopic [-4 (-9 to -2) vs -2 (-6 to 0), P=0.007] in RRDCD. Eyes with RRDCD had larger extent of retinal detachment (P=0.007). In RRDCD, 34.62% of eyes presented with multiple holes (P=0.044) and 25.00% with macular holes (P=0.012), compared with 20.66% and 14.08% in RRD. High myopia (P=0.039), low IOP (P=0.017), and larger extent of retinal detachment (P<0.001) were significant and independent risk factors for developing CD. CONCLUSION For CD in RRD, related factors include BCVA, IOP, lens status, refractive error, extent of retinal detachment, number of holes, and macular hole. Larger extent of retinal detachment, high myopia, and low IOP are significant and independent risk factors. PMID:27500106

  4. Temporal trends in mammal responses to fire reveals the complex effects of fire regime attributes.

    PubMed

    Lindenmayer, David B; Blanchard, Wade; MacGregor, Christopher; Barton, Philip; Banks, Sam C; Crane, Mason; Michael, Damian; Okada, Sachiko; Berry, Laurence; Florance, Daniel; Gill, Malcolm

    2016-03-01

    Fire is a major ecological process in many ecosystems worldwide. We sought to identify which attributes of fire regimes affect temporal change in the presence and abundance of Australian native mammals. Our detailed study was underpinned by time series data on 11 mammal species at 97 long-term sites in southeastern Australia between 2003 and 2013. We explored how temporal aspects of fire regimes influenced the presence and conditional abundance of species. The key fire regime components examined were: (1) severity of a major fire in 2003, (2) interval between the last major fire (2003) and the fire prior to that, and (3) number of past fires. Our long-term data set enabled quantification of the interactions between survey year and each fire regime variable: an ecological relationship missing from temporally restricted studies. We found no evidence of any appreciable departures from the assumption of independence of the sites. Multiple aspects of fire regimes influenced temporal variation in the presence and abundance of mammals. The best models indicated that six of the 11 species responded to two or more fire regime variables, with two species influenced by all three fire regime attributes. Almost all species responded to time since fire, either as an interaction with survey year or as a main effect. Fire severity or its interaction with survey year was important for most terrestrial rodents. The number of fires at a site was significant for terrestrial rodents and several other species. Our findings contain evidence of the effects on native mammals of heterogeneity in fire regimes. Temporal response patterns of mammal species were influenced by multiple fire regime attributes, often in conjunction with survey year. This underscores the critical importance of long-term studies of biota that are coupled with data sets characterized by carefully documented fire history, severity, and frequency. Long-term studies are essential to predict animal responses to fires and

  5. Role of connexin channels in the retinal light response of a diurnal rodent

    PubMed Central

    Palacios-Muñoz, Angelina; Escobar, Maria J.; Vielma, Alex; Araya, Joaquín; Astudillo, Aland; Valdivia, Gonzalo; García, Isaac E.; Hurtado, José; Schmachtenberg, Oliver; Martínez, Agustín D.; Palacios, Adrian G.

    2014-01-01

    Several studies have shown that connexin channels play an important role in retinal neural coding in nocturnal rodents. However, the contribution of these channels to signal processing in the retina of diurnal rodents remains unclear. To gain insight into this problem, we studied connexin expression and the contribution of connexin channels to the retinal light response in the diurnal rodent Octodon degus (degu) compared to rat, using in vivo ERG recording under scotopic and photopic light adaptation. Analysis of the degu genome showed that the common retinal connexins present a high degree of homology to orthologs expressed in other mammals, and expression of Cx36 and Cx43 was confirmed in degu retina. Cx36 localized mainly to the outer and inner plexiform layers (IPLs), while Cx43 was expressed mostly in cells of the retinal pigment epithelium. Under scotopic conditions, the b-wave response amplitude was strongly reduced by 18-β-glycyrrhetinic acid (β-GA) (−45.1% in degu, compared to −52.2% in rat), suggesting that connexins are modulating this response. Remarkably, under photopic adaptation, β-GA increased the ERG b-wave amplitude in degu (+107.2%) while reducing it in rat (−62.3%). Moreover, β-GA diminished the spontaneous action potential firing rate in ganglion cells (GCs) and increased the response latency of ON and OFF GCs. Our results support the notion that connexins exert a fine-tuning control of the retinal light response and have an important role in retinal neural coding. PMID:25202238

  6. Blockade of pathological retinal ganglion cell hyperactivity improves optogenetically evoked light responses in rd1 mice

    PubMed Central

    Barrett, John M.; Degenaar, Patrick; Sernagor, Evelyne

    2015-01-01

    Retinitis pigmentosa (RP) is a progressive retinal dystrophy that causes visual impairment and eventual blindness. Retinal prostheses are the best currently available vision-restoring treatment for RP, but only restore crude vision. One possible contributing factor to the poor quality of vision achieved with prosthetic devices is the pathological retinal ganglion cell (RGC) hyperactivity that occurs in photoreceptor dystrophic disorders. Gap junction blockade with meclofenamic acid (MFA) was recently shown to diminish RGC hyperactivity and improve the signal-to-noise ratio (SNR) of RGC responses to light flashes and electrical stimulation in the rd10 mouse model of RP. We sought to extend these results to spatiotemporally patterned optogenetic stimulation in the faster-degenerating rd1 model and compare the effectiveness of a number of drugs known to disrupt rd1 hyperactivity. We crossed rd1 mice with a transgenic mouse line expressing the light-sensitive cation channel channelrhodopsin2 (ChR2) in RGCs, allowing them to be stimulated directly using high-intensity blue light. We used 60-channel ITO multielectrode arrays to record ChR2-mediated RGC responses from wholemount, ex-vivo retinas to full-field and patterned stimuli before and after application of MFA, 18-β-glycyrrhetinic acid (18BGA, another gap junction blocker) or flupirtine (Flu, a Kv7 potassium channel opener). All three drugs decreased spontaneous RGC firing, but 18BGA and Flu also decreased the sensitivity of RGCs to optogenetic stimulation. Nevertheless, all three drugs improved the SNR of ChR2-mediated responses. MFA also made it easier to discern motion direction of a moving bar from RGC population responses. Our results support the hypothesis that reduction of pathological RGC spontaneous activity characteristic in retinal degenerative disorders may improve the quality of visual responses in retinal prostheses and they provide insights into how best to achieve this for optogenetic prostheses

  7. Blockade of pathological retinal ganglion cell hyperactivity improves optogenetically evoked light responses in rd1 mice.

    PubMed

    Barrett, John M; Degenaar, Patrick; Sernagor, Evelyne

    2015-01-01

    Retinitis pigmentosa (RP) is a progressive retinal dystrophy that causes visual impairment and eventual blindness. Retinal prostheses are the best currently available vision-restoring treatment for RP, but only restore crude vision. One possible contributing factor to the poor quality of vision achieved with prosthetic devices is the pathological retinal ganglion cell (RGC) hyperactivity that occurs in photoreceptor dystrophic disorders. Gap junction blockade with meclofenamic acid (MFA) was recently shown to diminish RGC hyperactivity and improve the signal-to-noise ratio (SNR) of RGC responses to light flashes and electrical stimulation in the rd10 mouse model of RP. We sought to extend these results to spatiotemporally patterned optogenetic stimulation in the faster-degenerating rd1 model and compare the effectiveness of a number of drugs known to disrupt rd1 hyperactivity. We crossed rd1 mice with a transgenic mouse line expressing the light-sensitive cation channel channelrhodopsin2 (ChR2) in RGCs, allowing them to be stimulated directly using high-intensity blue light. We used 60-channel ITO multielectrode arrays to record ChR2-mediated RGC responses from wholemount, ex-vivo retinas to full-field and patterned stimuli before and after application of MFA, 18-β-glycyrrhetinic acid (18BGA, another gap junction blocker) or flupirtine (Flu, a Kv7 potassium channel opener). All three drugs decreased spontaneous RGC firing, but 18BGA and Flu also decreased the sensitivity of RGCs to optogenetic stimulation. Nevertheless, all three drugs improved the SNR of ChR2-mediated responses. MFA also made it easier to discern motion direction of a moving bar from RGC population responses. Our results support the hypothesis that reduction of pathological RGC spontaneous activity characteristic in retinal degenerative disorders may improve the quality of visual responses in retinal prostheses and they provide insights into how best to achieve this for optogenetic prostheses

  8. Visual pattern recognition in Drosophila is invariant for retinal position.

    PubMed

    Tang, Shiming; Wolf, Reinhard; Xu, Shuping; Heisenberg, Martin

    2004-08-13

    Vision relies on constancy mechanisms. Yet, these are little understood, because they are difficult to investigate in freely moving organisms. One such mechanism, translation invariance, enables organisms to recognize visual patterns independent of the region of their visual field where they had originally seen them. Tethered flies (Drosophila melanogaster) in a flight simulator can recognize visual patterns. Because their eyes are fixed in space and patterns can be displayed in defined parts of their visual field, they can be tested for translation invariance. Here, we show that flies recognize patterns at retinal positions where the patterns had not been presented before. PMID:15310908

  9. Selectivity for multiple stimulus features in retinal ganglion cells.

    PubMed

    Fairhall, Adrienne L; Burlingame, C Andrew; Narasimhan, Ramesh; Harris, Robert A; Puchalla, Jason L; Berry, Michael J

    2006-11-01

    Under normal viewing conditions, retinal ganglion cells transmit to the brain an encoded version of the visual world. The retina parcels the visual scene into an array of spatiotemporal features, and each ganglion cell conveys information about a small set of these features. We study the temporal features represented by salamander retinal ganglion cells by stimulating with dynamic spatially uniform flicker and recording responses using a multi-electrode array. While standard reverse correlation methods determine a single stimulus feature--the spike-triggered average--multiple features can be relevant to spike generation. We apply covariance analysis to determine the set of features to which each ganglion cell is sensitive. Using this approach, we found that salamander ganglion cells represent a rich vocabulary of different features of a temporally modulated visual stimulus. Individual ganglion cells were sensitive to at least two and sometimes as many as six features in the stimulus. While a fraction of the cells can be described by a filter-and-fire cascade model, many cells have feature selectivity that has not previously been reported. These reverse models were able to account for 80-100% of the information encoded by ganglion cells. PMID:16914609

  10. A Reaction-Diffusion Model of Cholinergic Retinal Waves

    PubMed Central

    Lansdell, Benjamin; Ford, Kevin; Kutz, J. Nathan

    2014-01-01

    Prior to receiving visual stimuli, spontaneous, correlated activity in the retina, called retinal waves, drives activity-dependent developmental programs. Early-stage waves mediated by acetylcholine (ACh) manifest as slow, spreading bursts of action potentials. They are believed to be initiated by the spontaneous firing of Starburst Amacrine Cells (SACs), whose dense, recurrent connectivity then propagates this activity laterally. Their inter-wave interval and shifting wave boundaries are the result of the slow after-hyperpolarization of the SACs creating an evolving mosaic of recruitable and refractory cells, which can and cannot participate in waves, respectively. Recent evidence suggests that cholinergic waves may be modulated by the extracellular concentration of ACh. Here, we construct a simplified, biophysically consistent, reaction-diffusion model of cholinergic retinal waves capable of recapitulating wave dynamics observed in mice retina recordings. The dense, recurrent connectivity of SACs is modeled through local, excitatory coupling occurring via the volume release and diffusion of ACh. In addition to simulation, we are thus able to use non-linear wave theory to connect wave features to underlying physiological parameters, making the model useful in determining appropriate pharmacological manipulations to experimentally produce waves of a prescribed spatiotemporal character. The model is used to determine how ACh mediated connectivity may modulate wave activity, and how parameters such as the spontaneous activation rate and sAHP refractory period contribute to critical wave size variability. PMID:25474327

  11. Retinal nerve fiber layer thickness and retinal vessel calibers in children with thalassemia minor

    PubMed Central

    Acer, Semra; Balcı, Yasemin I; Pekel, Gökhan; Ongun, Tuğba T; Polat, Aziz; Çetin, Ebru N; Yağcı, Ramazan

    2016-01-01

    Objectives: Evaluation of the peripapillary retinal nerve fiber layer thickness, subfoveal choroidal thickness, and retinal vessel caliber measurements in children with thalassemia minor. Methods: In this cross-sectional and comparative study, 30 thalassemia minor patients and 36 controls were included. Heidelberg spectral domain optical coherence tomography was used for peripapillary retinal nerve fiber layer thickness, subfoveal choroidal thickness, and retinal vessel caliber measurements. Results: There was no statistically significant difference in retinal nerve fiber layer thickness and subfoveal choroidal thickness between the two groups (p > 0.05). There was no correlation between retinal nerve fiber layer thickness and hemoglobin values. Both the arterioral and venular calibers were higher in thalassemia minor group (p < 0.05). Conclusion: There is increased retinal arterioral and venular calibers in children with thalassemia minor compared with controls. PMID:27540484

  12. Climatic stress increases forest fire severity across the western United States.

    PubMed

    van Mantgem, Phillip J; Nesmith, Jonathan C B; Keifer, MaryBeth; Knapp, Eric E; Flint, Alan; Flint, Lorriane

    2013-09-01

    Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after accounting for fire defences and injuries, and appeared to influence the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across geographical regions, major genera and tree sizes. Our findings support recent physiological evidence showing that both drought and heating from fire can impair xylem conductivity. Warming trends have been linked to increasing probabilities of severe fire weather and fire spread; our results suggest that warming may also increase forest fire severity (the number of trees killed) independent of fire intensity (the amount of heat released during a fire). PMID:23869626

  13. Climatic stress increases forest fire severity across the western United States

    USGS Publications Warehouse

    van Mantgem, Philip J.; Nesmith, Jonathan C. B.; Keifer, MaryBeth; Knapp, Eric E.; Flint, Alan; Flint, Lorriane

    2013-01-01

    Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after accounting for fire defences and injuries, and appeared to influence the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across geographical regions, major genera and tree sizes. Our findings support recent physiological evidence showing that both drought and heating from fire can impair xylem conductivity. Warming trends have been linked to increasing probabilities of severe fire weather and fire spread; our results suggest that warming may also increase forest fire severity (the number of trees killed) independent of fire intensity (the amount of heat released during a fire).

  14. Retinal fundus imaging in mouse models of retinal diseases.

    PubMed

    Alex, Anne F; Heiduschka, Peter; Eter, Nicole

    2013-01-01

    The development of in vivo retinal fundus imaging in mice has opened a new research horizon, not only in ophthalmic research. The ability to monitor the dynamics of vascular and cellular changes in pathological conditions, such as neovascularization or degeneration, longitudinally without the need to sacrifice the mouse, permits longer observation periods in the same animal. With the application of the high-resolution confocal scanning laser ophthalmoscopy in experimental mouse models, access to a large spectrum of imaging modalities in vivo is provided. PMID:23150359

  15. Computational fire modeling for aircraft fire research

    SciTech Connect

    Nicolette, V.F.

    1996-11-01

    This report summarizes work performed by Sandia National Laboratories for the Federal Aviation Administration. The technical issues involved in fire modeling for aircraft fire research are identified, as well as computational fire tools for addressing those issues, and the research which is needed to advance those tools in order to address long-range needs. Fire field models are briefly reviewed, and the VULCAN model is selected for further evaluation. Calculations are performed with VULCAN to demonstrate its applicability to aircraft fire problems, and also to gain insight into the complex problem of fires involving aircraft. Simulations are conducted to investigate the influence of fire on an aircraft in a cross-wind. The interaction of the fuselage, wind, fire, and ground plane is investigated. Calculations are also performed utilizing a large eddy simulation (LES) capability to describe the large- scale turbulence instead of the more common k-{epsilon} turbulence model. Additional simulations are performed to investigate the static pressure and velocity distributions around a fuselage in a cross-wind, with and without fire. The results of these simulations provide qualitative insight into the complex interaction of a fuselage, fire, wind, and ground plane. Reasonable quantitative agreement is obtained in the few cases for which data or other modeling results exist Finally, VULCAN is used to quantify the impact of simplifying assumptions inherent in a risk assessment compatible fire model developed for open pool fire environments. The assumptions are seen to be of minor importance for the particular problem analyzed. This work demonstrates the utility of using a fire field model for assessing the limitations of simplified fire models. In conclusion, the application of computational fire modeling tools herein provides both qualitative and quantitative insights into the complex problem of aircraft in fires.

  16. Argus II retinal prosthesis system: An update.

    PubMed

    Rachitskaya, Aleksandra V; Yuan, Alex

    2016-09-01

    This review focuses on a description of the Argus II retinal prosthesis system (Argus II; Second Sight Medical Products, Sylmar, CA) that was approved for humanitarian use by the FDA in 2013 in patients with retinitis pigmentosa with bare or no light perception vision. The article describes the components of Argus II, the studies on the implant, and future directions. PMID:26855177

  17. Fundus autofluorescence applications in retinal imaging.

    PubMed

    Gabai, Andrea; Veritti, Daniele; Lanzetta, Paolo

    2015-05-01

    Fundus autofluorescence (FAF) is a relatively new imaging technique that can be used to study retinal diseases. It provides information on retinal metabolism and health. Several different pathologies can be detected. Peculiar AF alterations can help the clinician to monitor disease progression and to better understand its pathogenesis. In the present article, we review FAF principles and clinical applications. PMID:26139802

  18. Fundus autofluorescence applications in retinal imaging

    PubMed Central

    Gabai, Andrea; Veritti, Daniele; Lanzetta, Paolo

    2015-01-01

    Fundus autofluorescence (FAF) is a relatively new imaging technique that can be used to study retinal diseases. It provides information on retinal metabolism and health. Several different pathologies can be detected. Peculiar AF alterations can help the clinician to monitor disease progression and to better understand its pathogenesis. In the present article, we review FAF principles and clinical applications. PMID:26139802

  19. Retinal cholesterol emboli during diagnostic cardiac catheterization.

    PubMed

    Blanco, V R; Morís, C; Barriales, V; González, C

    2000-11-01

    Retinal embolism is a highly infrequent complication of cardiac catheterization of thrombotic, lipidic, and calcific etiology. We provide the first reported clinical case of retinal embolism caused by cholesterol crystal without systemic adverse effects as a severe complication of diagnostic cardiac catheterization. Cathet. Cardiovasc. Intervent. 51:323-325, 2000. PMID:11066118

  20. People, El Niño southern oscillation and fire in Australia: fire regimes and climate controls in hummock grasslands.

    PubMed

    Bliege Bird, Rebecca; Bird, Douglas W; Codding, Brian F

    2016-06-01

    While evidence mounts that indigenous burning has a significant role in shaping pyrodiversity, the processes explaining its variation across local and external biophysical systems remain limited. This is especially the case with studies of climate-fire interactions, which only recognize an effect of humans on the fire regime when they act independently of climate. In this paper, we test the hypothesis that an anthropogenic fire regime (fire incidence, size and extent) does not covary with climate. In the lightning regime, positive El Niño southern oscillation (ENSO) values increase lightning fire incidence, whereas La Niña (and associated increases in prior rainfall) increase fire size. ENSO has the opposite effect in the Martu regime, decreasing ignitions in El Niño conditions without affecting fire size. Anthropogenic ignition rates covary positively with high antecedent rainfall, whereas fire size varies only with high temperatures and unpredictable winds, which may reduce control over fire spread. However, total area burned is similarly predicted by antecedent rainfall in both regimes, but is driven by increases in fire size in the lightning regime, and fire number in the anthropogenic regime. We conclude that anthropogenic regimes covary with climatic variation, but detecting the human-climate-fire interaction requires multiple measures of both fire regime and climate.This article is part of the themed issue 'The interaction of fire and mankind'. PMID:27216513

  1. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2004-01-01

    Seven companies mined fire clay in four states during 2003. From 1984 to 1992, production declined to 383 kt (422,000 st) from a high of 1.04 Mt (1.14 million st) as markets for clay-based refractories declined. Since 1992, production levels have been erratic, ranging from 383 kt (422,000 st) in 1992 and 2001 to 583 kt (642,000 st) in 1995. Production in 2003, based on preliminary data, was estimated to be around 450 kt (496,000 st) with a value of about $10.5 million. This was about the same as in 2002. Missouri remained the leading producer state, followed by South Carolina, Ohio and California.

  2. Delayed rectifier K channels contribute to contrast adaptation in mammalian retinal ganglion cells

    PubMed Central

    Weick, Michael; Demb, Jonathan B.

    2011-01-01

    SUMMARY Retinal ganglion cells adapt by reducing their sensitivity during periods of high contrast. Contrast adaptation in the firing response depends on both presynaptic and intrinsic mechanisms. Here, we investigated intrinsic mechanisms for contrast adaptation in OFF Alpha ganglion cells in the in vitro guinea pig retina. Using either visual stimulation or current injection, we show that brief depolarization evoked spiking and suppressed firing during subsequent depolarization. The suppression could be explained by Na channel inactivation, as shown in salamander cells. However, brief hyperpolarization in the physiological range (5–10 mV) also suppressed firing during subsequent depolarization. This suppression was sensitive selectively to blockers of delayed-rectifier K channels (KDR). Somatic membrane patches showed TEA-sensitive KDR currents with activation near −25 mV and removal of inactivation at voltages negative to Vrest. Brief periods of hyperpolarization apparently remove KDR inactivation and thereby increase the channel pool available to suppress excitability during subsequent depolarization. PMID:21745646

  3. Restoring visual function to blind mice with a photoswitch that exploits electrophysiological remodeling of retinal ganglion cells

    PubMed Central

    Tochitsky, Ivan; Polosukhina, Aleksandra; Degtyar, Vadim E.; Gallerani, Nicholas; Smith, Caleb M.; Friedman, Aaron; Van Gelder, Russell N.; Trauner, Dirk; Kaufer, Daniela; Kramer, Richard H.

    2014-01-01

    Summary Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are blinding diseases caused by the degeneration of rods and cones, leaving the remainder of the visual system unable to respond to light. Here we report a chemical photoswitch named DENAQ that restores retinal responses to white light of intensity similar to ordinary daylight. A single intraocular injection of DENAQ photosensitizes the blind retina for days, restoring electrophysiological and behavioral responses with no toxicity. Experiments on mouse strains with functional, non-functional, or degenerated rods and cones show that DENAQ is effective only in retinas with degenerated photoreceptors. DENAQ confers light sensitivity on a hyperpolarization-activated inward current that is enhanced in degenerated retina, enabling optical control of retinal ganglion cell firing The acceptable light sensitivity, favorable spectral sensitivity, and selective targeting to diseased tissue make DENAQ a prime drug candidate for vision restoration in patients with end-stage RP and AMD. PMID:24559673

  4. Restoring visual function to blind mice with a photoswitch that exploits electrophysiological remodeling of retinal ganglion cells.

    PubMed

    Tochitsky, Ivan; Polosukhina, Aleksandra; Degtyar, Vadim E; Gallerani, Nicholas; Smith, Caleb M; Friedman, Aaron; Van Gelder, Russell N; Trauner, Dirk; Kaufer, Daniela; Kramer, Richard H

    2014-02-19

    Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are blinding diseases caused by the degeneration of rods and cones, leaving the remainder of the visual system unable to respond to light. Here, we report a chemical photoswitch named DENAQ that restores retinal responses to white light of intensity similar to ordinary daylight. A single intraocular injection of DENAQ photosensitizes the blind retina for days, restoring electrophysiological and behavioral responses with no toxicity. Experiments on mouse strains with functional, nonfunctional, or degenerated rods and cones show that DENAQ is effective only in retinas with degenerated photoreceptors. DENAQ confers light sensitivity on a hyperpolarization-activated inward current that is enhanced in degenerated retina, enabling optical control of retinal ganglion cell firing. The acceptable light sensitivity, favorable spectral sensitivity, and selective targeting to diseased tissue make DENAQ a prime drug candidate for vision restoration in patients with end-stage RP and AMD. PMID:24559673

  5. New mouse primary retinal degeneration (rd-3)

    SciTech Connect

    Chang, B.; Hawes, N.L.; Roderick, T.H. ); Heckenlively, J.R. )

    1993-04-01

    A new mouse retinal degeneration that appears to be an excellent candidate for modeling human retinitis pigmentosa is reported. In this degeneration, called rd-3, differentiation proceeds postnatally through 2 weeks, and photoreceptor degeneration starts by 3 weeks. The rod photoreceptor loss is essentially complete by 5 weeks, whereas remnant cone cells are seen through 7 weeks. This is the only mouse homozygous retinal degeneration reported to date in which photoreceptors are initially normal. Crosses with known mouse retinal degenerations rd, Rds, nr, and pcd are negative for retinal degeneration in offspring, and linkage analysis places rd-3 on mouse chromosome 1 at 10 [+-]2.5 cM distal to Akp-1. Homology mapping suggests that the homologous human locus should be on chromosome 1q. 32 refs., 3 figs., 3 tabs.

  6. Retinal pigment epithelium in incontinentia pigmenti.

    PubMed

    Mensheha-Manhart, O; Rodrigues, M M; Shields, J A; Shannon, G M; Mirabelli, R P

    1975-04-01

    An 18-month-old white girl with incontinentia pigmenti presented clinically with leukokoria of the right eye. B-scan ultrasound demonstrated a retrolental mass consistent with a detached retina. Histologic examination of the skin revealed changes compatible with the intermediate verrucous phase of the disease. Microscopic examination of the right eye showed retinal detachment and nodular proliferation of the retinal pigment epithelium. The nodules contained macrophages laden with melanin and lipofuscin. An unusually large amount of lipofuscin was present for a child of this age. The basic pigmentary abnormality may affect the retinal pigment epithelium, resulting in changes in the overlying neurosensory retina that may lead to the retinal dysplasia or retinal detachemnt often associated with this condition. PMID:1119517

  7. The cell stress machinery and retinal degeneration.

    PubMed

    Athanasiou, Dimitra; Aguilà, Monica; Bevilacqua, Dalila; Novoselov, Sergey S; Parfitt, David A; Cheetham, Michael E

    2013-06-27

    Retinal degenerations are a group of clinically and genetically heterogeneous disorders characterised by progressive loss of vision due to neurodegeneration. The retina is a highly specialised tissue with a unique architecture and maintaining homeostasis in all the different retinal cell types is crucial for healthy vision. The retina can be exposed to a variety of environmental insults and stress, including light-induced damage, oxidative stress and inherited mutations that can lead to protein misfolding. Within retinal cells there are different mechanisms to cope with disturbances in proteostasis, such as the heat shock response, the unfolded protein response and autophagy. In this review, we discuss the multiple responses of the retina to different types of stress involved in retinal degenerations, such as retinitis pigmentosa, age-related macular degeneration and glaucoma. Understanding the mechanisms that maintain and re-establish proteostasis in the retina is important for developing new therapeutic approaches to fight blindness. PMID:23684651

  8. Texton-based segmentation of retinal vessels.

    PubMed

    Adjeroh, Donald A; Kandaswamy, Umasankar; Odom, J Vernon

    2007-05-01

    With improvements in fundus imaging technology and the increasing use of digital images in screening and diagnosis, the issue of automated analysis of retinal images is gaining more serious attention. We consider the problem of retinal vessel segmentation, a key issue in automated analysis of digital fundus images. We propose a texture-based vessel segmentation algorithm based on the notion of textons. Using a weak statistical learning approach, we construct textons for retinal vasculature by designing filters that are specifically tuned to the structural and photometric properties of retinal vessels. We evaluate the performance of the proposed approach using a standard database of retinal images. On the DRIVE data set, the proposed method produced an average performance of 0.9568 specificity at 0.7346 sensitivity. This compares well with the best-published results on the data set 0.9773 specificity at 0.7194 sensitivity [Proc. SPIE5370, 648 (2004)]. PMID:17429484

  9. Texton-based segmentation of retinal vessels

    NASA Astrophysics Data System (ADS)

    Adjeroh, Donald A.; Kandaswamy, Umasankar; Odom, J. Vernon

    2007-05-01

    With improvements in fundus imaging technology and the increasing use of digital images in screening and diagnosis, the issue of automated analysis of retinal images is gaining more serious attention. We consider the problem of retinal vessel segmentation, a key issue in automated analysis of digital fundus images. We propose a texture-based vessel segmentation algorithm based on the notion of textons. Using a weak statistical learning approach, we construct textons for retinal vasculature by designing filters that are specifically tuned to the structural and photometric properties of retinal vessels. We evaluate the performance of the proposed approach using a standard database of retinal images. On the DRIVE data set, the proposed method produced an average performance of 0.9568 specificity at 0.7346 sensitivity. This compares well with the best-published results on the data set 0.9773 specificity at 0.7194 sensitivity [Proc. SPIE5370, 648 (2004)].

  10. Fire Suppression and Response

    NASA Technical Reports Server (NTRS)

    Ruff, Gary A.

    2004-01-01

    This report is concerned with the following topics regarding fire suppression:What is the relative effectiveness of candidate suppressants to extinguish a representative fire in reduced gravity, including high-O2 mole fraction, low -pressure environments? What are the relative advantages and disadvantages of physically acting and chemically-acting agents in spacecraft fire suppression? What are the O2 mole fraction and absolute pressure below which a fire cannot exist? What effect does gas-phase radiation play in the overall fire and post-fire environments? Are the candidate suppressants effective to extinguish fires on practical solid fuels? What is required to suppress non-flaming fires (smoldering and deep seated fires) in reduced gravity? How can idealized space experiment results be applied to a practical fire scenario? What is the optimal agent deployment strategy for space fire suppression?

  11. Regulation of Irregular Neuronal Firing by Autaptic Transmission

    NASA Astrophysics Data System (ADS)

    Guo, Daqing; Wu, Shengdun; Chen, Mingming; Perc, Matjaž; Zhang, Yangsong; Ma, Jingling; Cui, Yan; Xu, Peng; Xia, Yang; Yao, Dezhong

    2016-05-01

    The importance of self-feedback autaptic transmission in modulating spike-time irregularity is still poorly understood. By using a biophysical model that incorporates autaptic coupling, we here show that self-innervation of neurons participates in the modulation of irregular neuronal firing, primarily by regulating the occurrence frequency of burst firing. In particular, we find that both excitatory and electrical autapses increase the occurrence of burst firing, thus reducing neuronal firing regularity. In contrast, inhibitory autapses suppress burst firing and therefore tend to improve the regularity of neuronal firing. Importantly, we show that these findings are independent of the firing properties of individual neurons, and as such can be observed for neurons operating in different modes. Our results provide an insightful mechanistic understanding of how different types of autapses shape irregular firing at the single-neuron level, and they highlight the functional importance of autaptic self-innervation in taming and modulating neurodynamics.

  12. Regulation of Irregular Neuronal Firing by Autaptic Transmission.

    PubMed

    Guo, Daqing; Wu, Shengdun; Chen, Mingming; Perc, Matjaž; Zhang, Yangsong; Ma, Jingling; Cui, Yan; Xu, Peng; Xia, Yang; Yao, Dezhong

    2016-01-01

    The importance of self-feedback autaptic transmission in modulating spike-time irregularity is still poorly understood. By using a biophysical model that incorporates autaptic coupling, we here show that self-innervation of neurons participates in the modulation of irregular neuronal firing, primarily by regulating the occurrence frequency of burst firing. In particular, we find that both excitatory and electrical autapses increase the occurrence of burst firing, thus reducing neuronal firing regularity. In contrast, inhibitory autapses suppress burst firing and therefore tend to improve the regularity of neuronal firing. Importantly, we show that these findings are independent of the firing properties of individual neurons, and as such can be observed for neurons operating in different modes. Our results provide an insightful mechanistic understanding of how different types of autapses shape irregular firing at the single-neuron level, and they highlight the functional importance of autaptic self-innervation in taming and modulating neurodynamics. PMID:27185280

  13. Regulation of Irregular Neuronal Firing by Autaptic Transmission

    PubMed Central

    Guo, Daqing; Wu, Shengdun; Chen, Mingming; Perc, Matjaž; Zhang, Yangsong; Ma, Jingling; Cui, Yan; Xu, Peng; Xia, Yang; Yao, Dezhong

    2016-01-01

    The importance of self-feedback autaptic transmission in modulating spike-time irregularity is still poorly understood. By using a biophysical model that incorporates autaptic coupling, we here show that self-innervation of neurons participates in the modulation of irregular neuronal firing, primarily by regulating the occurrence frequency of burst firing. In particular, we find that both excitatory and electrical autapses increase the occurrence of burst firing, thus reducing neuronal firing regularity. In contrast, inhibitory autapses suppress burst firing and therefore tend to improve the regularity of neuronal firing. Importantly, we show that these findings are independent of the firing properties of individual neurons, and as such can be observed for neurons operating in different modes. Our results provide an insightful mechanistic understanding of how different types of autapses shape irregular firing at the single-neuron level, and they highlight the functional importance of autaptic self-innervation in taming and modulating neurodynamics. PMID:27185280

  14. Synchronizing retinal activity in both eyes disrupts binocular map development in the optic tectum.

    PubMed

    Brickley, S G; Dawes, E A; Keating, M J; Grant, S

    1998-02-15

    Spatiotemporal correlations in the pattern of spontaneous and evoked retinal ganglion cell (RGC) activity are believed to influence the topographic organization of connections throughout the developing visual system. We have tested this hypothesis by examining the effects of interfering with these potential activity cues during development on the functional organization of binocular maps in the Xenopus frog optic tectum. Paired recordings combined with cross-correlation analyses demonstrated that exposing normal frogs to a continuous 1 Hz of stroboscopic illumination synchronized the firing of all three classes of RGC projecting to the tectum and induced similar patterns of temporally correlated activity across both lobes of the nucleus. Embryonic and eye-rotated larval animals were reared until early adulthood under equivalent stroboscopic conditions. The maps formed by each RGC class in the contralateral tectum showed normal topography and stratification after strobe rearing, but with consistently enlarged multiunit receptive fields. Maps of the ipsilateral eye, formed by crossed isthmotectal axons, showed significant disorder and misalignment with direct visual input from the retina, and in the eye-rotated animals complete compensatory reorientation of these maps usually induced by this procedure failed to occur. These findings suggest that refinement of retinal arbors in the tectum and the ability of crossed isthmotectal arbors to establish binocular convergence with these retinal afferents are disrupted when they all fire together. Our data thus provide direct experimental evidence that spatiotemporal activity patterns within and between the two eyes regulate the precision of their developing connections. PMID:9454857

  15. Sildenafil alters retinal function in mouse carriers of retinitis pigmentosa.

    PubMed

    Nivison-Smith, Lisa; Zhu, Yuan; Whatham, Andrew; Bui, Bang V; Fletcher, Erica L; Acosta, Monica L; Kalloniatis, Michael

    2014-11-01

    Sildenafil, the active ingredient in Viagra, has been reported to cause transient visual disturbance from inhibition of phosphodiesterase 6 (PDE6), a key enzyme in the visual phototransduction pathway. This study investigated the effects of sildenafil on the rd1(+/-) mouse, a model for carriers of Retinitis Pigmentosa which exhibit normal vision but may have a lower threshold for cellular stress caused by sildenafil due to a heterozygous mutation in PDE6. Sildenafil caused a dose-dependent decrease in electroretinogram (ERG) responses of normal mice which mostly recovered two days post administration. In contrast, rd1(+/-) mice exhibited a significantly reduced photoreceptor and a supernormal bipolar cell response to sildenafil within 1 h of treatment. Carrier mice retinae took two weeks to return to baseline levels suggesting sildenafil has direct effects on both the inner and outer retina and these effects differ significantly between normal and carrier mice. Anatomically, an increase in expression of the early apoptotic marker, cytochrome C in rd1(+/-) mice indicated that the effects of sildenafil on visual function may lead to degeneration. The results of this study are significant considering approximately 1 in 50 people are likely to be carriers of recessive traits leading to retinal degeneration. PMID:25239397

  16. Primary Reactions in Retinal Proteins

    NASA Astrophysics Data System (ADS)

    Diller, R.

    Conversion of sunlight into energy or information and their storage on a chemical level is essential for life on earth. An important family of chromoproteins performing these tasks is that of retinal binding proteins. Prominent examples are rhodopsin (Rh) [1,2] as the visual pigment in vertebrate and invertebrate animals, the archaeal rhodopsins bacteriorhodopsin (BR) [3] as a light driven proton pump, halorhodopsin (HR) [4,5] as a light driven chloride pump, sensory rhodopsin I and II (SRI, SRII) [6] as photoreceptors, and proteorhodopsin (PR) [7] as another bacterial proton pump.

  17. Understanding independence

    NASA Astrophysics Data System (ADS)

    Annan, James; Hargreaves, Julia

    2016-04-01

    In order to perform any Bayesian processing of a model ensemble, we need a prior over the ensemble members. In the case of multimodel ensembles such as CMIP, the historical approach of ``model democracy'' (i.e. equal weight for all models in the sample) is no longer credible (if it ever was) due to model duplication and inbreeding. The question of ``model independence'' is central to the question of prior weights. However, although this question has been repeatedly raised, it has not yet been satisfactorily addressed. Here I will discuss the issue of independence and present a theoretical foundation for understanding and analysing the ensemble in this context. I will also present some simple examples showing how these ideas may be applied and developed.

  18. Retinal Microvascular Signs and Risk of Stroke: The Multi-Ethnic Study of Atherosclerosis (MESA)

    PubMed Central

    Kawasaki, Ryo; Xie, Jing; Cheung, Ning; Lamoureux, Ecosse; Klein, Ronald; Klein, Barbara EK; Cotch, Mary Frances; Sharrett, A Richey; Shea, Steven; Wong, Tien Y.

    2012-01-01

    Background and Purpose Small vessel disease contributes to the pathophysiology of stroke, and retinal microvascular signs have been linked to risk of stroke. We examined the relationship of retinal signs with incident stroke in a multi-ethnic cohort. Methods The Multi-Ethnic Study of Atherosclerosis (MESA) is a prospective cohort study that enrolled participants without clinical cardiovascular diseases from six United States communities between 2000–02. Of the participants, 4,849 (71.2%) had fundus photography performed in 2002–04. Retinopathy and retinal vessel caliber were assessed from retinal images. Stroke risk factors including high-sensitivity C-reactive protein (hsCRP), carotid artery intima-media thickness (IMT) and coronary artery calcium (CAC) were measured using standardized protocols. Incident stroke was confirmed from medical record review and death certificates. Results After 6 years of follow-up, there were 62 incident strokes. Narrower retinal arteriolar caliber was associated with increased risk of stroke after adjusting for conventional cardiovascular risk factors (adjusted incidence rate ratio [IRR] 2.83, 95% confidence interval [CI] 1.34–5.95, p=0.006; adjusted hazard ratio [HR] 3.01, 95% CI 1.29–6.99, p=0.011). Retinopathy in persons without diabetes was associated with increased risk of stroke (adjusted IRR 2.96, 95% CI 1.50–5.84, p=0.002; adjusted HR 3.07, 95%CI 1.17–8.09, p=0.023). These associations remained significant after adjusting for hsCRP, carotid IMT or CAC. Conclusions Narrower retinal arteriolar caliber and retinopathy in non-diabetic persons were associated with increased risk of stroke in this relatively healthy multi-ethnic cohort independent of traditional risk factors and measures of atherosclerosis. The association between narrower retinal arteriolar caliber and stroke warrants further investigation. PMID:23111439

  19. Retinal microvascular caliber and chronic kidney disease in an Asian population.

    PubMed

    Sabanayagam, Charumathi; Shankar, Anoop; Koh, David; Chia, Kee Seng; Saw, Seang Mei; Lim, Su Chi; Tai, E Shyong; Wong, Tien Yin

    2009-03-01

    Retinal arteriolar narrowing is a marker of microvascular damage from elevated blood pressure. Between August 2004 and June 2006, the authors examined the association between retinal vascular diameter and chronic kidney disease in a population-based cohort of 3,280 community-dwelling adults of Malay ethnicity aged 40-80 years living in Singapore. Chronic kidney disease was defined as 1) an estimated glomerular filtration rate (eGFR) of <60 mL/minute/1.73 m(2) from serum creatinine or 2) the presence of micro/macroalbuminuria defined as urinary albumin:creatinine ratios of > or = 17 mg/g for men and > or = 25 mg/g for women. Retinal arteriolar and venular diameters were measured and summarized as central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE). Individuals with reduced CRAE were more likely to have chronic kidney disease than those with increased CRAE. After controlling for age, gender, education, smoking, diabetes, hypertension, body mass index, and total and high density lipoprotein cholesterol, the authors found the odds ratio comparing the smallest with the largest CRAE quartile to be 1.42 (95% confidence interval: 1.03, 1.96; P(trend) = 0.02) for eGFR of <60 mL/minute/1.73 m(2) and 1.80 (95% confidence interval: 1.11, 2.91; P(trend) = 0.01) for micro/macroalbuminuria. Retinopathy was also found to be positively associated with both eGFR and micro/macroalbuminuria. Retinal venular diameter was not associated with chronic kidney disease. These data suggest that retinal arteriolar narrowing is associated with chronic kidney disease, independent of diabetes and hypertension. PMID:19092170

  20. The evolutionary diversity of insect retinal mosaics: Common design principles and emerging molecular logic

    PubMed Central

    Wernet, Mathias F.; Perry, Michael W.; Desplan, Claude

    2015-01-01

    Independent evolution has resulted in a vast diversity of eyes. Despite the lack of a common Bauplan or ancestral structure, similar developmental strategies are used. For instance, different classes of photoreceptor cells (PRs) are distributed stochastically and/or localized in different regions of the retina. Here we focus on recent progress made towards understanding the molecular principles behind patterning retinal mosaics of insects, one of the most diverse groups of animals adapted to life on land, in the air, under water, or on the water surface. Morphological, physiological, and behavioral studies from many species provide detailed descriptions of the vast variation in retinal design and function. By integrating this knowledge with recent progress in the characterization of insect Rhodopsins as well as insight from the model organism Drosophila melanogaster, we seek to identify the molecular logic behind the adaptation of retinal mosaics to an animal’s habitat and way of life. PMID:26025917

  1. Demarcation laser photocoagulation induced retinal necrosis and rupture resulting in large retinal tear formation.

    PubMed

    Quezada, Carlos; Pieramici, Dante J; Matsui, Rodrigo; Rabena, Melvin; Graue, Federico

    2015-06-01

    Retinal tears after laser photocoagulation are a rare complication that occurs after intense laser. It is talked about among retina specialist occurring particularly at the end of a surgical case while applying endophotocoagulation; to the best our knowledge, there are no reports in the literature of a large retinal tear induced after attempted in-office demarcation laser photocoagulation (DLP) that simulated a giant retinal tear. DLP has been employed in the management of selected cases of macula sparring rhegmatogenous retinal detachment (RRD). Even though extension of the retinal detachment through the "laser barrier" is considered a failure of treatment, few complications have been described with the use of this less invasive retinal detachment repair technique. We describe a case of a high myopic woman who initially was treated with demarcation laser photocoagulation for an asymptomatic retinal detachment associated with a single horseshoe tear and a full thickness large retinal tear was created where the laser was placed. Intense laser photocoagulation resulted in abrupt laser induced retinal necrosis and rupture creating this large retinal break. Proper laser technique should reduce the risks associated with this procedure. PMID:25770055

  2. Wildland fire simulation by WRF-Fire

    NASA Astrophysics Data System (ADS)

    Mandel, J.; Beezley, J. D.; Kochanski, A.; Kondratenko, V. Y.; Sousedik, B.

    2010-12-01

    This presentation will give an overview of the principles, algorithms, and features of the coupled atmosphere-wildland fire software WRF-Fire. WRF-Fire consists of a fire-spread model, based on a modified Rothermel's formula implemented by the level-set method, coupled with the Weather Research and Forecasting model (WRF). The code has been publicly released with WRF and it is supported by the developers. The WRF infrastructure is used for parallel execution, with additional improvements. In addition to the input of standard atmospheric data, the WRF Preprocessing System (WPS) has been extended for the input of high-resolution topography and fuel data. The fuel models can be easily modified by the user. The components of the wind and of the terrain gradient are interpolated to the fire model mesh by accurate formulas which respect grid staggering. Ignition models include point, drip-torch line, and, in near future, a developed fire perimeter from standard web sources, with an atmosphere spin-up. Companion presentations will describe a validation on the FireFlux experiment, and a simulation of a real wildland fire in a terrain with sharp gradients. This work was supported by NSF grants CNS-0719641 and ATM-0835579. Simulation of the FireFlux grass fire experiment (Clements et al., 2007) in WRF-Fire.

  3. Cavefish eye loss in response to an early block in retinal differentiation progression.

    PubMed

    Stemmer, Manuel; Schuhmacher, Laura-Nadine; Foulkes, Nicholas S; Bertolucci, Cristiano; Wittbrodt, Joachim

    2015-02-15

    The troglomorphic phenotype shared by diverse cave-dwelling animals is regarded as a classical example of convergent evolution. One unresolved question is whether the characteristic eye loss in diverse cave species is based on interference with the same genetic program. Phreatichthys andruzzii, a Somalian cavefish, has evolved under constant conditions in complete darkness and shows severe troglomorphic characteristics, such as complete loss of eyes, pigments and scales. During early embryonic development, a complete eye is formed but is subsequently lost. In Astyanax mexicanus, another blind cavefish, eye loss has been attributed to interference during eye field patterning. To address whether similar pathways have been targeted by evolution independently, we investigated the retinal development of P. andruzzii, studying the expression of marker genes involved in eye patterning, morphogenesis, differentiation and maintenance. In contrast to Astyanax, patterning of the eye field and evagination of the optic vesicles proceeds without obvious deviation. However, the subsequent differentiation of retinal cell types is arrested during generation of the first-born cell type, retinal ganglion cells, which also fail to project correctly to the optic tectum. Eye degeneration in both species is driven by progressive apoptosis. However, it is retinal apoptosis in Phreatichthys that progresses in a wave-like manner and eliminates progenitor cells that fail to differentiate, in contrast to Astyanax, where lens apoptosis appears to serve as a driving force. Thus, evolution has targeted late retinal differentiation events, indicating that there are several ways to discontinue the development and maintenance of an eye. PMID:25617433

  4. Automated detection of retinal layers from OCT spectral-domain images of healthy eyes

    NASA Astrophysics Data System (ADS)

    Giovinco, Gaspare; Savastano, Maria Cristina; Ventre, Salvatore; Tamburrino, Antonello

    2015-12-01

    Optical coherence tomography (OCT) has become one of the most relevant diagnostic tools for retinal diseases. Besides being a non-invasive technique, one distinguished feature is its unique capability of providing (in vivo) cross-sectional view of the retina. Specifically, OCT images show the retinal layers. From the clinical point of view, the identification of the retinal layers opens new perspectives to study the correlation between morphological and functional aspects of the retinal tissue. The main contribution of this paper is a new method/algorithm for the automated segmentation of cross-sectional images of the retina of healthy eyes, obtained by means of spectral-domain optical coherence tomography (SD-OCT). Specifically, the proposed segmentation algorithm provides the automated detection of different retinal layers. Tests on experimental SD-OCT scans performed by three different instruments/manufacturers have been successfully carried out and compared to a manual segmentation made by an independent ophthalmologist, showing the generality and the effectiveness of the proposed method.

  5. FIRE SERVICE TRAINING.

    ERIC Educational Resources Information Center

    BERNDT, WILLIAM M.; AND OTHERS

    STUDENTS MAY USE THIS REVISED MANUAL IN FIRE STATION OR TRAINING CENTER EXTENSION PROGRAMS FOR IMPROVING THE COMPETENCIES AND SKILLS OF LOCAL FIRE PERSONNEL IN THE SPECIALIZED FIELD OF FIRE SERVICE. IT WAS DEVELOPED BY A STATEWIDE COMMITTEE OF FIRE-FIGHTING CONSULTANTS AND ADVISORY GROUPS. THE 26 CHAPTERS PROVIDE BOTH BASIC AND ADVANCED TECHNICAL…

  6. Children and Home Fires

    MedlinePlus

    CHILDREN AND HOME FIRES Fast Facts Children under the age of five are twice as likely to die in a home fire than the rest of the population, and child-playing fires are the leading cause of fire deaths among ...

  7. Fire Safety Technician

    ERIC Educational Resources Information Center

    Moore, Pam

    2007-01-01

    Fire protection is one of the most important considerations in the construction and operation of industrial plants and commercial buildings. Fire insurance rates are determined by fire probability factors, such as the type of construction, ease of transporting personnel, and the quality and quantity of fire protection equipment available. Because…

  8. Measurement of retinal blood velocity

    NASA Astrophysics Data System (ADS)

    Winchester, Leonard W., Jr.; Chou, Nee-Yin

    2006-02-01

    A fundus camera was modified to illuminate the retina of a rabbit model with low power laser light in order to obtain laser speckle images. A fast-exposure charge-coupled device (CCD) camera was used to capture laser speckle images of the retina. Image acquisition was synchronized with the arterial pulses of the rabbit to ensure that all images are obtained at the same point in the cardiac cycle. The rabbits were sedated and a speculum was inserted to prevent the eyelid from closing. Both albino (New Zealand; pigmented (Dutch belted) rabbits were used in the study. The rabbit retina is almost avascular. The measurements are obtained for choroidal tissue as well as retinal tissue. Because the retina is in a region of high metabolism, blood velocity is strongly affected by blood oxygen saturation. Measurements of blood velocity obtained over a wide range of O II saturations (58%-100%) showed that blood velocity increases with decreasing O II saturation. For most experiments, the left eye of the rabbit was used for laser measurements whereas the right eye served as a control. No observable difference between pre- and post-experimented eye was noted. Histological examinations of retinal tissue subjected to repeated laser measurements showed no indication of tissue damage.

  9. Fixation strategies for retinal immunohistochemistry.

    PubMed

    Stradleigh, Tyler W; Ishida, Andrew T

    2015-09-01

    Immunohistochemical and ex vivo anatomical studies have provided many glimpses of the variety, distribution, and signaling components of vertebrate retinal neurons. The beauty of numerous images published to date, and the qualitative and quantitative information they provide, indicate that these approaches are fundamentally useful. However, obtaining these images entailed tissue handling and exposure to chemical solutions that differ from normal extracellular fluid in composition, temperature, and osmolarity. Because the differences are large enough to alter intercellular and intracellular signaling in neurons, and because retinae are susceptible to crush, shear, and fray, it is natural to wonder if immunohistochemical and anatomical methods disturb or damage the cells they are designed to examine. Tissue fixation is typically incorporated to guard against this damage and is therefore critically important to the quality and significance of the harvested data. Here, we describe mechanisms of fixation; advantages and disadvantages of using formaldehyde and glutaraldehyde as fixatives during immunohistochemistry; and modifications of widely used protocols that have recently been found to improve cell shape preservation and immunostaining patterns, especially in proximal retinal neurons. PMID:25892361

  10. Fixation Strategies For Retinal Immunohistochemistry

    PubMed Central

    Stradleigh, Tyler W.; Ishida, Andrew T.

    2015-01-01

    Immunohistochemical and ex vivo anatomical studies have provided many glimpses of the variety, distribution, and signaling components of vertebrate retinal neurons. The beauty of numerous images published to date, and the qualitative and quantitative information they provide, indicate that these approaches are fundamentally useful. However, obtaining these images entailed tissue handling and exposure to chemical solutions that differ from normal extracellular fluid in composition, temperature, and osmolarity. Because the differences are large enough to alter intercellular and intracellular signaling in neurons, and because retinae are susceptible to crush, shear, and fray, it is natural to wonder if immunohistochemical and anatomical methods disturb or damage the cells they are designed to examine. Tissue fixation is typically incorporated to guard against this damage and is therefore critically important to the quality and significance of the harvested data. Here, we describe mechanisms of fixation; advantages and disadvantages of using formaldehyde and glutaraldehyde as fixatives during immunohistochemistry; and modifications of widely used protocols that have recently been found to improve cell shape preservation and immunostaining patterns, especially in proximal retinal neurons. PMID:25892361

  11. A mechanical model of retinal detachment

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Siegel, Michael

    2012-08-01

    We present a model of the mechanical and fluid forces associated with exudative retinal detachments where the retinal photoreceptor cells separate, typically from the underlying retinal pigment epithelium (RPE). By computing the total fluid volume flow arising from transretinal, vascular and RPE pump currents, we determine the conditions under which the subretinal fluid pressure exceeds the maximum yield stress holding the retina and RPE together, giving rise to an irreversible, extended retinal delamination. We also investigate localized, blister-like retinal detachments by balancing mechanical tension in the retina with both the retina-RPE adhesion energy and the hydraulic pressure jump across the retina. For detachments induced by traction forces, we find a critical radius beyond which the blister is unstable to growth. Growth of a detached blister can also be driven by inflamed lesions in which the tissue has a higher choroidal hydraulic conductivity, has insufficient RPE pump activity, or has defective adhesion bonds. We determine the parameter regimes in which the blister either becomes unstable to growth, remains stable and finite-sized, or shrinks, allowing possible healing. The corresponding stable blister radius and shape are calculated. Our analysis provides a quantitative description of the physical mechanisms involved in exudative retinal detachments and can help guide the development of retinal reattachment protocols or preventative procedures.

  12. Retinal microvascular network attenuation in Alzheimer's disease

    PubMed Central

    Williams, Michael A.; McGowan, Amy J.; Cardwell, Chris R.; Cheung, Carol Y.; Craig, David; Passmore, Peter; Silvestri, Giuliana; Maxwell, Alexander P.; McKay, Gareth J.

    2015-01-01

    Introduction Cerebral small-vessel disease has been implicated in the development of Alzheimer's disease (AD). The retinal microvasculature enables the noninvasive visualization and evaluation of the systemic microcirculation. We evaluated retinal microvascular parameters in a case-control study of AD patients and cognitively normal controls. Methods Retinal images were computationally analyzed and quantitative retinal parameters (caliber, fractal dimension, tortuosity, and bifurcation) measured. Regression models were used to compute odds ratios (OR) and confidence intervals (CI) for AD with adjustment for confounders. Results Retinal images were available in 213 AD participants and 294 cognitively normal controls. Persons with lower venular fractal dimension (OR per standard deviation [SD] increase, 0.77 [CI: 0.62–0.97]) and lower arteriolar tortuosity (OR per SD increase, 0.78 [CI: 0.63–0.97]) were more likely to have AD after appropriate adjustment. Discussion Patients with AD have a sparser retinal microvascular network and retinal microvascular variation may represent similar pathophysiological events within the cerebral microvasculature of patients with AD. PMID:26634224

  13. Optical Coherence Tomography Angiography in Retinal Diseases

    PubMed Central

    Chalam, K. V.; Sambhav, Kumar

    2016-01-01

    Optical coherence tomography angiography (OCTA) is a new, non-invasive imaging system that generates volumetric data of retinal and choroidal layers. It has the ability to show both structural and blood flow information. Split-spectrum amplitude-decorrelation angiography (SSADA) algorithm (a vital component of OCTA software) helps to decrease the signal to noise ratio of flow detection thus enhancing visualization of retinal vasculature using motion contrast. Published studies describe potential efficacy for OCTA in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age related macular degeneration (AMD), retinal vascular occlusions and sickle cell disease. OCTA provides a detailed view of the retinal vasculature, which allows accurate delineation of microvascular abnormalities in diabetic eyes and vascular occlusions. It helps quantify vascular compromise depending upon the severity of diabetic retinopathy. OCTA can also elucidate the presence of choroidal neovascularization (CNV) in wet AMD. In this paper, we review the knowledge, available in English language publications regarding OCTA, and compare it with the conventional angiographic standard, fluorescein angiography (FA). Finally, we summarize its potential applications to retinal vascular diseases. Its current limitations include a relatively small field of view, inability to show leakage, and tendency for image artifacts. Further larger studies will define OCTA's utility in clinical settings and establish if the technology may offer a non-invasive option of visualizing the retinal vasculature, enabling us to decrease morbidity through early detection and intervention in retinal diseases. PMID:27195091

  14. Optical Coherence Tomography Angiography in Retinal Diseases.

    PubMed

    Chalam, K V; Sambhav, Kumar

    2016-01-01

    Optical coherence tomography angiography (OCTA) is a new, non-invasive imaging system that generates volumetric data of retinal and choroidal layers. It has the ability to show both structural and blood flow information. Split-spectrum amplitude-decorrelation angiography (SSADA) algorithm (a vital component of OCTA software) helps to decrease the signal to noise ratio of flow detection thus enhancing visualization of retinal vasculature using motion contrast. Published studies describe potential efficacy for OCTA in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age related macular degeneration (AMD), retinal vascular occlusions and sickle cell disease. OCTA provides a detailed view of the retinal vasculature, which allows accurate delineation of microvascular abnormalities in diabetic eyes and vascular occlusions. It helps quantify vascular compromise depending upon the severity of diabetic retinopathy. OCTA can also elucidate the presence of choroidal neovascularization (CNV) in wet AMD. In this paper, we review the knowledge, available in English language publications regarding OCTA, and compare it with the conventional angiographic standard, fluorescein angiography (FA). Finally, we summarize its potential applications to retinal vascular diseases. Its current limitations include a relatively small field of view, inability to show leakage, and tendency for image artifacts. Further larger studies will define OCTA's utility in clinical settings and establish if the technology may offer a non-invasive option of visualizing the retinal vasculature, enabling us to decrease morbidity through early detection and intervention in retinal diseases. PMID:27195091

  15. Fire-walking

    NASA Astrophysics Data System (ADS)

    Willey, David

    2010-09-01

    This article gives a brief history of fire-walking and then deals with the physics behind fire-walking. The author has performed approximately 50 fire-walks, took the data for the world's hottest fire-walk and was, at one time, a world record holder for the longest fire-walk (www.dwilley.com/HDATLTW/Record_Making_Firewalks.html). He currently teaches Physics for the University of Pittsburgh at Johnstown, USA.

  16. Fire-Walking

    ERIC Educational Resources Information Center

    Willey, David

    2010-01-01

    This article gives a brief history of fire-walking and then deals with the physics behind fire-walking. The author has performed approximately 50 fire-walks, took the data for the world's hottest fire-walk and was, at one time, a world record holder for the longest fire-walk (www.dwilley.com/HDATLTW/Record_Making_Firewalks.html). He currently…

  17. Purinergic signaling in retinal degeneration and regeneration.

    PubMed

    Reichenbach, Andreas; Bringmann, Andreas

    2016-05-01

    Purinergic signaling is centrally involved in mediating the degeneration of the injured and diseased retina, the induction of retinal gliosis, and the protection of the retinal tissue from degeneration. Dysregulated calcium signaling triggered by overactivation of P2X7 receptors is a crucial step in the induction of neuronal and microvascular cell death under pathogenic conditions like ischemia-hypoxia, elevated intraocular pressure, and diabetes, respectively. Overactivation of P2X7 plays also a pathogenic role in inherited and age-related photoreceptor cell death and in the age-related dysfunction and degeneration of the retinal pigment epithelium. Gliosis of micro- and macroglial cells, which is induced and/or modulated by purinergic signaling and associated with an impaired homeostatic support to neurons, and the ATP-mediated propagation of retinal gliosis from a focal injury into the surrounding noninjured tissue are involved in inducing secondary cell death in the retina. On the other hand, alterations in the glial metabolism of extracellular nucleotides, resulting in a decreased level of ATP and an increased level of adenosine, may be neuroprotective in the diseased retina. Purinergic signals stimulate the proliferation of retinal glial cells which contributes to glial scarring which has protective effects on retinal degeneration and adverse effects on retinal regeneration. Pharmacological modulation of purinergic receptors, e.g., inhibition of P2X and activation of adenosine receptors, may have clinical importance for the prevention of photoreceptor, neuronal, and microvascular cell death in diabetic retinopathy, retinitis pigmentosa, age-related macular degeneration, and glaucoma, respectively, for the clearance of retinal edema, and the inhibition of dysregulated cell proliferation in proliferative retinopathies. This article is part of a Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'. PMID:25998275

  18. Retinal venous pressure: the role of endothelin.

    PubMed

    Flammer, Josef; Konieczka, Katarzyna

    2015-01-01

    The retinal venous pressure (RVP) can be measured non-invasively. While RVP is equal to or slightly above intraocular pressure (IOP) in healthy people, it is often markedly increased in patients with eye or systemic diseases. Beside a mechanical obstruction, the main cause of such an elevation is a local dysregulation of a retinal vein, particularly a constriction induced by endothelin-1 (ET-1). A local increase of ET-1 can result from a high plasma level, as ET-1 can diffuse from the fenestrated capillaries of the choroid into the optic nerve head (ONH), bypassing the blood retinal barrier. A local increase can also result from increased local production either by a sick neighboring artery or retinal tissue. Generally, the main factors increasing ET-1 are inflammations and hypoxia, either locally or in a remote organ. RVP is known to be increased in patients with glaucoma, retinal vein occlusion (RVO), diabetic retinopathy, high mountain disease, and primary vascular dysregulation (PVD). PVD is the major vascular component of Flammer syndrome (FS). An increase of RVP decreases perfusion pressure, which heightens the risk for hypoxia. An increase of RVP also elevates transmural pressure, which in turn heightens the risk for retinal edema. In patients with RVO, a high level of RVP may not only be a consequence but also a potential cause of the occlusion; therefore, it risks causing a vicious circle. Narrow retinal arteries and particularly dilated retinal veins are known risk indicators for future cardiovascular events. As the major cause for such a retinal venous dilatation is an increased RVP, RVP may likely turn out to be an even stronger predictor. PMID:26504500

  19. Cancer-associated retinopathy with retinal phlebitis.

    PubMed

    Ohnishi, Y; Ohara, S; Sakamoto, T; Kohno, T; Nakao, F

    1993-12-01

    A 50-year-old man with cancer-associated retinopathy was investigated using light and electron microscopy, immunofluorescence studies, and western blotting. He had visual disturbance, ring-like scotoma, and night blindness bilaterally. There were narrowed retinal arterioles and dilated retinal venules. Oral corticosteroid therapy had positive effects. Immunostaining using the patient's serum revealed a positive reaction in the ganglion cell layer of normal retina. Western blotting showed that the patient's serum antibody reacted with normal retinal proteins of 24 and 48 kDa. Multiple metastases were evident at autopsy. PMID:8110675

  20. Retinal isomerization dynamics in dry bacteriorhodopsin films

    NASA Astrophysics Data System (ADS)

    Colonna, Anne; Groma, Géza I.; Vos, Marten H.

    2005-10-01

    The primary photoprocesses in neutral and acid forms of oriented dried bacteriorhodopsin films were investigated by femtosecond absorption spectroscopy. The excitation energy dependence of the signals was used to distinguish photochemistry from processes involving photophysics of photocycle intermediates. Both the kinetics and the quantum yield of all- trans excited state decay by retinal photoisomerization and subsequent J → K transition were found to be very similar as in hydrated environments. Therefore, unlike slower photocycle phases, communication of the retinal with the environment does not play a role in retinal isomerization. Our results are important for understanding recent nonlinear optical applications of such films.

  1. Retinal Stimulation on Rabbit Using Complementary Metal Oxide Semiconductor Based Multichip Flexible Stimulator toward Retinal Prosthesis

    NASA Astrophysics Data System (ADS)

    Tokuda, Takashi; Asano, Ryosuke; Sugitani, Sachie; Taniyama, Mari; Terasawa, Yasuo; Nunoshita, Masahiro; Nakauchi, Kazuaki; Fujikado, Takashi; Tano, Yasuo; Ohta, Jun

    2008-04-01

    The Functionality of a complementary metal oxide semiconductor (CMOS) LSI-based, multichip flexible retinal stimulator was demonstrated in retinal stimulation experiments on rabbits. A 1×4-configured multichip stimulator was fabricated for application to experiments on animals. An experimental procedure including surgical operations was developed, and retinal stimulation was performed with the fabricated multichip stimulator. Neural responses on the visual cortex were successfully evoked by the fabricated stimulator. The stimulator is confirmed to be applicable to acute animal experiments.

  2. Spontaneous neural activity in the primary visual cortex of retinal degenerated rats.

    PubMed

    Wang, Yi; Chen, Ke; Xu, Ping; Ng, Tsz Kin; Chan, Leanne Lai Hang

    2016-06-01

    Retinal degeneration (RD) models have been widely used to study retinal degenerative diseases for a long time. The biological and electrophysiological presentations of changes in the retina during degeneration progress have been well investigated; thus, the present study is aimed at investigating the electrophysiological effects of RD in the primary visual cortex. We extracellularly recorded the spontaneous neural activities in the primary visual cortex of RD rats. The firing rate, interspike interval (ISI) and Lempel-Ziv (LZ) complexity of spontaneous neural activities were subsequently analyzed. When compared to the control group, it was found that the neurons in primary visual cortex of the RD model fired more frequently. In addition, there was a decrease in LZ complexity of spontaneous neural firing in the RD model. These results suggest that the progress of RD may not only affect the retina itself but also the primary visual cortex, which may result in an unbalanced inhibition-excitation system as well as the decreased arising rate of new patterns of spontaneous activities. PMID:27132087

  3. 'Independence' Panorama

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for 'Independence' Panorama (QTVR)

    This is the Spirit 'Independence' panorama, acquired on martian days, or sols, 536 to 543 (July 6 to 13, 2005), from a position in the 'Columbia Hills' near the summit of 'Husband Hill.' The summit of 'Husband Hill' is the peak near the right side of this panorama and is about 100 meters (328 feet) away from the rover and about 30 meters (98 feet) higher in elevation. The rocky outcrops downhill and on the left side of this mosaic include 'Larry's Lookout' and 'Cumberland Ridge,' which Spirit explored in April, May, and June of 2005.

    The panorama spans 360 degrees and consists of 108 individual images, each acquired with five filters of the rover's panoramic camera. The approximate true color of the mosaic was generated using the camera's 750-, 530-, and 480-nanometer filters. During the 8 martian days, or sols, that it took to acquire this image, the lighting varied considerably, partly because of imaging at different times of sol, and partly because of small sol-to-sol variations in the dustiness of the atmosphere. These slight changes produced some image seams and rock shadows. These seams have been eliminated from the sky portion of the mosaic to better simulate the vista a person standing on Mars would see. However, it is often not possible or practical to smooth out such seams for regions of rock, soil, rover tracks or solar panels. Such is the nature of acquiring and assembling large panoramas from the rovers.

  4. Fire safety distances for open pool fires

    NASA Astrophysics Data System (ADS)

    Sudheer, S.; Kumar, Lokendra; Manjunath, B. S.; Pasi, Amit; Meenakshi, G.; Prabhu, S. V.

    2013-11-01

    Fire accidents that carry huge loss with them have increased in the previous two decades than at any time in the history. Hence, there is a need for understanding the safety distances from different fires with different fuels. Fire safety distances are computed for different open pool fires. Diesel, gasoline and hexane are used as fuels for circular pool diameters of 0.5 m, 0.7 m and 1.0 m. A large square pool fire of 4 m × 4 m is also conducted with diesel as a fuel. All the prescribed distances in this study are purely based on the thermal analysis. IR camera is used to get the thermal images of pool fires and there by the irradiance at different locations is computed. The computed irradiance is presented with the threshold heat flux limits for human beings.

  5. Lhx2 Is an Essential Factor for Retinal Gliogenesis and Notch Signaling

    PubMed Central

    de Melo, Jimmy; Zibetti, Cristina; Clark, Brian S.; Hwang, Woochang; Miranda-Angulo, Ana L.; Qian, Jiang

    2016-01-01

    during all stages of MG development. We also show that Lhx2 regulates directly the expression of components of the Notch signaling pathway, which promotes retinal Müller gliogenesis, as well as multiple gliogenic transcription factors. We further demonstrate that Lhx2 is required for Hes5-dependent gliogenesis. This study identifies Lhx2 as a central transcriptional regulator of both Notch-dependent and Notch-independent components of retinal gliogenesis. PMID:26911688

  6. Nuclear Migration During Retinal Development

    PubMed Central

    Baye, Lisa M.; Link, Brian A.

    2009-01-01

    In this review we focus on the mechanisms, regulation, and cellular consequences of nuclear migration in the developing retina. In the nervous system, nuclear migration is prominent during both proliferative and post-mitotic phases of development. Interkinetic nuclear migration is the process where the nucleus oscillates from the apical to basal surfaces in proliferative neuroepithelia. Proliferative nuclear movement occurs in step with the cell cycle, with M-phase being confined to the apical surface and G1-, S-, and G2-phases occurring at more basal locations. Later, following cell cycle exit, some neuron precursors migrate by nuclear translocation. In this mode of cellular migration, nuclear movement is the driving force for motility. Following discussion of the key components and important regulators for each of these processes, we present an emerging model where interkinetic nuclear migration functions to distinguish cell fates among retinal neuroepithelia. PMID:17560964

  7. Regulatory and Economic Considerations of Retinal Drugs.

    PubMed

    Shah, Ankoor R; Williams, George A

    2016-01-01

    The advent of anti-VEGF therapy for neovascular age-related macular degeneration and macular edema secondary to retinal vein occlusion and diabetes mellitus has prevented blindness in tens of thousands of people. However, the costs of these drugs are without precedent in ophthalmic drug therapeutics. An analysis of the financial implications of retinal drugs and the impact of the Food and Drug Administration on treatment of retinal disease must include not only an evaluation of the direct costs of the drugs and the costs associated with their administration, but also the cost savings which accrue from their clinical benefit. This chapter will discuss the financial and regulatory issues associated with retinal drugs. PMID:26502165

  8. Retinal vein occlusion: pathophysiology and treatment options

    PubMed Central

    Karia, Niral

    2010-01-01

    This paper reviews the current thinking about retinal vein occlusion. It gives an overview of its pathophysiology and discusses the evidence behind the various established and emerging treatment paradigms. PMID:20689798

  9. Expression Profiling of Developing Zebrafish Retinal Cells.

    PubMed

    Mullally, Madelyn; Albrecht, Caitlin; Horton, Mary; Laboissonniere, Lauren A; Goetz, Jillian J; Chowdhury, Rebecca; Manning, Alicia; Wester, Andrea K; Bose, Quinton; Trimarchi, Jeffrey M

    2016-08-01

    During retinal development, a variety of different types of neurons are produced. Understanding how each of these types of retinal nerve cells is generated is important from a developmental biology perspective. It is equally important if one is interested in how to regenerate cells after an injury or a disease. To gain more insight into how retinal neurons develop in the zebrafish, we performed single-cell mRNA profiling and in situ hybridizations (ISHs) on retinal sections and whole-mount zebrafish. Through the series of ISHs, designed and performed solely by undergraduate students in the laboratory, we were able to retrospectively identify our single-cell mRNA profiles as most likely coming from developing amacrine cells. Further analysis of these profiles will reveal genes that can be mutated using genome editing techniques. Together these studies increase our knowledge of the genes driving development of different cell types in the zebrafish retina. PMID:26982811

  10. Retinal Detachment: Torn or Detached Retina Treatment

    MedlinePlus

    ... of these procedures create a scar that helps seal the retina to the back of the eye. ... around the retinal tear. The scarring that results seals the retina to the underlying tissue, helping to ...

  11. What Is Next for Retinal Gene Therapy?

    PubMed Central

    Vandenberghe, Luk H.

    2015-01-01

    The field of gene therapy for retinal blinding disorders is experiencing incredible momentum, justified by hopeful results in early stage clinical trials for inherited retinal degenerations. The premise of the use of the gene as a drug has come a long way, and may have found its niche in the treatment of retinal disease. Indeed, with only limited treatment options available for retinal indications, gene therapy has been proven feasible, safe, and effective and may lead to durable effects following a single injection. Here, we aim at putting into context the promise and potential, the technical, clinical, and economic boundaries limiting its application and development, and speculate on a future in which gene therapy is an integral component of ophthalmic clinical care. PMID:25877395

  12. Doppler optical coherence tomography of retinal circulation.

    PubMed

    Tan, Ou; Wang, Yimin; Konduru, Ranjith K; Zhang, Xinbo; Sadda, SriniVas R; Huang, David

    2012-01-01

    Noncontact retinal blood flow measurements are performed with a Fourier domain optical coherence tomography (OCT) system using a circumpapillary double circular scan (CDCS) that scans around the optic nerve head at 3.40 mm and 3.75 mm diameters. The double concentric circles are performed 6 times consecutively over 2 sec. The CDCS scan is saved with Doppler shift information from which flow can be calculated. The standard clinical protocol calls for 3 CDCS scans made with the OCT beam passing through the superonasal edge of the pupil and 3 CDCS scan through the inferonal pupil. This double-angle protocol ensures that acceptable Doppler angle is obtained on each retinal branch vessel in at least 1 scan. The CDCS scan data, a 3-dimensional volumetric OCT scan of the optic disc scan, and a color photograph of the optic disc are used together to obtain retinal blood flow measurement on an eye. We have developed a blood flow measurement software called "Doppler optical coherence tomography of retinal circulation" (DOCTORC). This semi-automated software is used to measure total retinal blood flow, vessel cross section area, and average blood velocity. The flow of each vessel is calculated from the Doppler shift in the vessel cross-sectional area and the Doppler angle between the vessel and the OCT beam. Total retinal blood flow measurement is summed from the veins around the optic disc. The results obtained at our Doppler OCT reading center showed good reproducibility between graders and methods (<10%). Total retinal blood flow could be useful in the management of glaucoma, other retinal diseases, and retinal diseases. In glaucoma patients, OCT retinal blood flow measurement was highly correlated with visual field loss (R(2)>0.57 with visual field pattern deviation). Doppler OCT is a new method to perform rapid, noncontact, and repeatable measurement of total retinal blood flow using widely available Fourier-domain OCT instrumentation. This new technology may improve the

  13. Fires Scorch Oregon

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In southwestern Oregon, the Florence Fire (north) and the Sour Biscuit Fire (south) continue to grow explosively. This image from the Landsat 7 Enhanced Thematic Mapper Plus was captured on July 29, 2002. The Florence Fire had grown to 50,000 acres and the Sour Biscuit Fire had grown to 16,000 acres. Numerous evacuation notices remain in effect. Thick smoke from the actively burning eastern perimeter of the Florence Fire is billowing southward and mingling with the Biscuit Fire smoke. Credit:Image provided by the USGS EROS Data Center Satellite Systems Branch.

  14. Diode laser contact transscleral retinal photocoagulation: a clinical study.

    PubMed Central

    McHugh, D A; Schwartz, S; Dowler, J G; Ulbig, M; Blach, R K; Hamilton, P A

    1995-01-01

    AIM--To examine the clinical efficacy of contact transscleral retinal photocoagulation with a diode laser. METHODS--Transscleral retinal photocoagulation was performed on 36 eyes. The conditions treated included peripheral retinal breaks associated with retinal detachments (30 eyes) and giant retinal tears (six eyes). Of the 30 eyes with retinal detachments, 28 underwent transscleral photocoagulation to the site of drainage of subretinal fluid in an attempt to reduce the risk of hemorrhage. RESULTS--Threshold lesions were obtained with irradiances of between 95.4 W/cm2 and 191 W/cm2. Satisfactory chorioretinal adhesion was achieved in all eyes with retinal breaks and giant retinal tears. The only significant complications of treatment encountered were punctate choroidal haemorrhages (three eyes). Drainage related choroidal haemorrhage following earlier photocoagulation occurred in two of 28 eyes. CONCLUSIONS--This study confirms the clinical potential of transscleral diode laser photocoagulation in the therapy of surgical retinal conditions. Images PMID:8562540

  15. Photoreceptor Cells Influence Retinal Vascular Degeneration in Mouse Models of Retinal Degeneration and Diabetes

    PubMed Central

    Liu, Haitao; Tang, Jie; Du, Yunpeng; Saadane, Aicha; Tonade, Deoye; Samuels, Ivy; Veenstra, Alex; Palczewski, Krzysztof; Kern, Timothy S.

    2016-01-01

    Purpose Loss of photoreceptor cells is associated with retinal vascular degeneration in retinitis pigmentosa, whereas the presence of photoreceptor cells is implicated in vascular degeneration in diabetic retinopathy. To investigate how both the absence and presence of photoreceptors could damage the retinal vasculature, we compared two mouse models of photoreceptor degeneration (opsin−/− and RhoP23H/P23H ) and control C57Bl/5J mice, each with and without diabetes. Methods Retinal thickness, superoxide, expression of inflammatory proteins, ERG and optokinetic responses, leukocyte cytotoxicity, and capillary degeneration were evaluated at 1 to 10 months of age using published methods. Results Retinal photoreceptor cells degenerated completely in the opsin mutants by 2 to 4 months of age, and visual function subsided correspondingly. Retinal capillary degeneration was substantial while photoreceptors were still present, but slowed after the photoreceptors degenerated. Diabetes did not further exacerbate capillary degeneration in these models of photoreceptor degeneration, but did cause capillary degeneration in wild-type animals. Photoreceptor cells, however, did not degenerate in wild-type diabetic mice, presumably because the stress responses in these cells were less than in the opsin mutants. Retinal superoxide and leukocyte damage to retinal endothelium contributed to the degeneration of retinal capillaries in diabetes, and leukocyte-mediated damage was increased in both opsin mutants during photoreceptor cell degeneration. Conclusions Photoreceptor cells affect the integrity of the retinal microvasculature. Deterioration of retinal capillaries in opsin mutants was appreciable while photoreceptor cells were present and stressed, but was less after photoreceptors degenerated. This finding proves relevant to diabetes, where persistent stress in photoreceptors likewise contributes to capillary degeneration. PMID:27548901

  16. The human dimension of fire regimes on Earth.

    PubMed

    Bowman, David M J S; Balch, Jennifer; Artaxo, Paulo; Bond, William J; Cochrane, Mark A; D'Antonio, Carla M; Defries, Ruth; Johnston, Fay H; Keeley, Jon E; Krawchuk, Meg A; Kull, Christian A; Mack, Michelle; Moritz, Max A; Pyne, Stephen; Roos, Christopher I; Scott, Andrew C; Sodhi, Navjot S; Swetnam, Thomas W; Whittaker, Robert

    2011-12-01

    Humans and their ancestors are unique in being a fire-making species, but 'natural' (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human-set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from 'natural' background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke-related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas-induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding

  17. The human dimension of fire regimes on Earth

    USGS Publications Warehouse

    Bowman, David M.J.S.; Balch, Jennifer; Artaxo, Paulo; Bond, William J.; Cochrane, Mark A.; D'Antonio, Carla M.; DeFries, Ruth; Johnston, Fay H.; Keeley, Jon E.; Krawchuk, Meg A.; Kull, Christian A.; Michelle, Mack; Moritz, Max A.; Pyne, Stephen; Roos, Christopher I.; Scott, Andrew C.; Sodhi, Navjot S.; Swetnam, Thomas W.

    2011-01-01

    Humans and their ancestors are unique in being a fire-making species, but 'natural' (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human-set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from 'natural' background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke-related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas-induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding

  18. Retinal synaptic regeneration via microfluidic guiding channels.

    PubMed

    Su, Ping-Jung; Liu, Zongbin; Zhang, Kai; Han, Xin; Saito, Yuki; Xia, Xiaojun; Yokoi, Kenji; Shen, Haifa; Qin, Lidong

    2015-01-01

    In vitro culture of dissociated retinal neurons is an important model for investigating retinal synaptic regeneration (RSR) and exploring potentials in artificial retina. Here, retinal precursor cells were cultured in a microfluidic chip with multiple arrays of microchannels in order to reconstruct the retinal neuronal synapse. The cultured retinal cells were physically connected through microchannels. Activation of electric signal transduction by the cells through the microchannels was demonstrated by administration of glycinergic factors. In addition, an image-based analytical method was used to quantify the synaptic connections and to assess the kinetics of synaptic regeneration. The rate of RSR decreased significantly below 100 μM of inhibitor glycine and then approached to a relatively constant level at higher concentrations. Furthermore, RSR was enhanced by chemical stimulation with potassium chloride. Collectively, the microfluidic synaptic regeneration chip provides a novel tool for high-throughput investigation of RSR at the cellular level and may be useful in quality control of retinal precursor cell transplantation. PMID:26314276

  19. Retinal Light Damage: Mechanisms and Protection

    PubMed Central

    Organisciak, Daniel T.; Vaughan, Dana K.

    2009-01-01

    By its action on rhodopsin, light triggers the well-known visual transduction cascade, but can also induce cell damage and death through phototoxic mechanisms -- a comprehensive understanding of which is still elusive despite more than 40 years of research. Herein, we integrate recent experimental findings to address several hypotheses of retinal light damage, premised in part on the close anatomical and metabolic relationships between the photoreceptors and the retinal pigment epithelium. We begin by reviewing the salient features of light damage, recently joined by evidence for retinal remodeling which has implications for the prognosis of recovery of function in retinal degenerations. We then consider select factors that influence the progression of the damage process and the extent of visual cell loss. Traditional, genetically-modified, and emerging animal models are discussed, with particular emphasis on cone visual cells. Exogenous and endogenous retinal protective factors are explored, with implications for light damage mechanisms and some suggested avenues for future research. Synergies are known to exist between our long term light environment and photoreceptor cell death in retinal disease. Understanding the molecular mechanisms of light damage in a variety of animal models can provide valuable insights into the effects of light in clinical disorders and may form the basis of future therapies to prevent or delay visual cell loss. PMID:19951742

  20. Retinal oxygenation via the choroidal circulation.

    PubMed Central

    Landers, M B

    1978-01-01

    The possibility of supplying normal amounts of oxygen to the inner layers of the retina by diffusion from the choroid in the presence of retinal arterial obstruction was studied in cats and rhesus monkeys. While the animals were under general anesthesia, an oxygen electrode was placed in the vitreous cavity immediately adjacent to the retina, and a retinal artery blocker probe was used to occlude various segments of the retina blood supply. The inspired oxygen concentration was alternated between 20% and 100%. The choroidal circulation was intermittently occluded by elevating the intraocular pressure. In all animals it was possible to return the oxygen tension of the innermost retina to normal concentrations or above while the retinal arterial circulation alone was occluded, by having the animal breathe 100% oxygen at one atmosphere pressure. This could not be done when the intraocular pressure was elevated to 85 mm Hg, occluding the choroidal as well as the retinal circulation. The electroretinogram and the visually evoked response were recorded in cats while the retinal circulation was occluded and the inspired oxygen concentration changed from 20% to 100% at one atmosphere pressure. The electroretinogram and the visually evoked response were extinguished by occluding the retinal circulation while the animal was breathing 20% oxygen, and these responses were returned to normal by changing to a 100% inspired oxygen concentration. Images FIGURE 6 PMID:112752

  1. [Gene therapy for inherited retinal dystrophies].

    PubMed

    Côco, Monique; Han, Sang Won; Sallum, Juliana Maria Ferraz

    2009-01-01

    The inherited retinal dystrophies comprise a large number of disorders characterized by a slow and progressive retinal degeneration. They are the result of mutations in genes that express in either the photoreceptor cells or the retinal pigment epithelium. The mode of inheritance can be autosomal dominant, autosomal recessive, X linked recessive, digenic or mitochondrial DNA inherited. At the moment, there is no treatment for these conditions and the patients can expect a progressive loss of vision. Accurate genetic counseling and support for rehabilitation are indicated. Research into the molecular and genetic basis of disease is continually expanding and improving the prospects for rational treatments. In this way, gene therapy, defined as the introduction of exogenous genetic material into human cells for therapeutic purposes, may ultimately offer the greatest treatment for the inherited retinal dystrophies. The eye is an attractive target for gene therapy because of its accessibility, immune privilege and translucent media. A number of retinal diseases affecting the eye have known gene defects. Besides, there is a well characterized animal model for many of these conditions. Proposals for clinical trials of gene therapy for inherited retinal degenerations owing to defects in the gene RPE65, have recently received ethical approval and the obtained preliminary results brought large prospects in the improvement on patient's quality of life. PMID:19820803

  2. Role of calcium-activated potassium channels in acetylcholine-induced vasodilation of rat retinal arterioles in vivo.

    PubMed

    Mori, Asami; Suzuki, Sachi; Sakamoto, Kenji; Nakahara, Tsutomu; Ishii, Kunio

    2011-01-01

    The vascular endothelium plays an important role in regulating retinal blood flow via actions of several vasodilators, including nitric oxide (NO), prostaglandin I₂, and an endothelium-derived hyperpolarizing factor (EDHF). Our previous in vivo studies demonstrated that acetylcholine (ACh) dilates the rat retinal arteriole partly through NO- and prostaglandin-independent pathway, possibly the EDHF-mediated pathway, but the underlying mechanism(s) remains to be elucidated. It has been suggested that activation of Ca²+-activated K+ (K(Ca)) channels contributes to the EDHF-mediated responses; therefore, the roles of K(Ca) channels in ACh-induced vasodilation of retinal arterioles were examined in rats. The retinal vascular responses were assessed by determining changes in diameters of retinal arterioles in ocular fundus images that were captured with an original fundus camera system. Intravitreal injection of charybdotoxin, an inhibitor of intermediate- and large-conductance K(Ca) (I/BK(Ca)) channels, or iberiotoxin, an inhibitor of large-conductance K(Ca) (BK(Ca)) channels, significantly reduced the ACh-induced vasodilation of retinal arterioles, whereas neither apamin, an inhibitor of small-conductance K(Ca) (SK(Ca)) channels, nor TRAM-34, an inhibitor of intermediate-conductance K(Ca) (IK(Ca)) channels, altered the response. The vasodilator response to ACh observed under the combined blockade of NO synthase and cyclooxygenase with N(G)-nitro-L-arginine methyl ester plus indomethacin was also diminished by iberiotoxin. Iberiotoxin did not affect the NO donor NOR3-induced vasodilation of retinal arterioles, whereas it significantly reduced the BK(Ca) channel opener BMS-191011-induced responses. These results suggest that activation of BK(Ca) channels is involved in the EDHF-mediated component of the vasodilator response to ACh in the rat retinal arterioles in vivo. PMID:20978884

  3. Tamponade in surgery for retinal detachment associated with proliferative vitreoretinopathy

    PubMed Central

    Schwartz, Stephen G; Flynn, Harry W; Lee, Wen-Hsiang; Wang, Xue

    2014-01-01

    Background Retinal detachment (RD) with proliferative vitreoretinopathy (PVR) often requires surgery to restore normal anatomy and to stabilize or improve vision. PVR usually occurs in association with recurrent RD (that is, after initial retinal re-attachment surgery) but occasionally may be associated with primary RD. Either way, a tamponade agent (gas or silicone oil) is needed during surgery to reduce the rate of postoperative recurrent RD. Objectives The objective of this review was to assess the relative safety and effectiveness of various tamponade agents used with surgery for retinal detachment (RD) complicated by proliferative vitreoretinopathy (PVR). Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 5), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to June 2013), EMBASE (January 1980 to June 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 26 June 2013. Selection criteria We included randomized controlled trials (RCTs) of participants undergoing surgery for RD associated with PVR that compared various tamponade agents. Data collection and analysis Two review authors screened the search results independently. We used the standard methodological procedures expected by The Cochrane Collaboration. PMID:24532038

  4. The Reduction of Retinal Autofluorescence Caused by Light Exposure

    PubMed Central

    Morgan, Jessica I. W.; Hunter, Jennifer J.; Merigan, William H.; Williams, David R.

    2009-01-01

    Purpose We have previously shown that long exposure to 568 nm light at levels below the maximum permissible exposure safety limit produces retinal damage preceded by a transient reduction in the autofluorescence of retinal pigment epithelial (RPE) cells in vivo. Here, we determine how the effects of exposure power and duration combine to produce this autofluorescence reduction and find the minimum exposure causing a detectable autofluorescence reduction. Methods Macaque retinas were imaged using a fluorescence adaptive optics scanning laser ophthalmoscope to resolve individual RPE cells in vivo. The retina was exposed to 568 nm light over a square subtending 0.5° with energies ranging from 1 J/cm2 to 788 J/cm2, where power and duration were independently varied. Results In vivo exposures of 5 J/cm2 and higher caused an immediate decrease in autofluorescence followed by either full autofluorescence recovery (exposures ≤ 210 J/cm2) or permanent RPE cell damage (exposures ≥ 247 J/cm2). No significant autofluorescence reduction was observed for exposures of 2 J/cm2 and lower. Reciprocity of exposure power and duration held for the exposures tested, implying that the total energy delivered to the retina, rather than its distribution in time, determines the amount of autofluorescence reduction. Conclusions That reciprocity holds is consistent with a photochemical origin, which may or may not cause retinal degeneration. The implementation of safe methods for delivering light to the retina requires a better understanding of the mechanism causing autofluorescence reduction. Finally, RPE imaging was demonstrated using light levels that do not cause a detectable reduction in autofluorescence. PMID:19628734

  5. Transcriptome analysis and molecular signature of human retinal pigment epithelium

    PubMed Central

    Strunnikova, N.V.; Maminishkis, A.; Barb, J.J.; Wang, F.; Zhi, C.; Sergeev, Y.; Chen, W.; Edwards, A.O.; Stambolian, D.; Abecasis, G.; Swaroop, A.; Munson, P.J.; Miller, S.S.

    2010-01-01

    Retinal pigment epithelium (RPE) is a polarized cell layer critical for photoreceptor function and survival. The unique physiology and relationship to the photoreceptors make the RPE a critical determinant of human vision. Therefore, we performed a global expression profiling of native and cultured human fetal and adult RPE and determined a set of highly expressed ‘signature’ genes by comparing the observed RPE gene profiles to the Novartis expression database (SymAtlas: http://wombat.gnf.org/index.html) of 78 tissues. Using stringent selection criteria of at least 10-fold higher expression in three distinct preparations, we identified 154 RPE signature genes, which were validated by qRT-PCR analysis in RPE and in an independent set of 11 tissues. Several of the highly expressed signature genes encode proteins involved in visual cycle, melanogenesis and cell adhesion and Gene ontology analysis enabled the assignment of RPE signature genes to epithelial channels and transporters (ClCN4, BEST1, SLCA20) or matrix remodeling (TIMP3, COL8A2). Fifteen RPE signature genes were associated with known ophthalmic diseases, and 25 others were mapped to regions of disease loci. An evaluation of the RPE signature genes in a recently completed AMD genomewide association (GWA) data set revealed that TIMP3, GRAMD3, PITPNA and CHRNA3 signature genes may have potential roles in AMD pathogenesis and deserve further examination. We propose that RPE signature genes are excellent candidates for retinal diseases and for physiological investigations (e.g. dopachrome tautomerase in melanogenesis). The RPE signature gene set should allow the validation of RPE-like cells derived from human embryonic or induced pluripotent stem cells for cell-based therapies of degenerative retinal diseases. PMID:20360305

  6. Allosteric modulation of retinal GABA receptors by ascorbic acid

    PubMed Central

    Calero, Cecilia I.; Vickers, Evan; Moraga Cid, Gustavo; Aguayo, Luis G.; von Gersdorff, Henrique; Calvo, Daniel J.

    2011-01-01

    Summary Ionotropic γ-aminobutyric acid receptors (GABAA and GABAC) belong to the cys-loop receptor family of ligand-gated ion channels. GABAC receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect of ascorbic acid on retinal GABA receptors has not been studied. Here we show that the function of GABAC and GABAA receptors is regulated by ascorbic acid. Patch-clamp recordings from bipolar cell terminals in goldfish retinal slices revealed that GABAC receptor-mediated currents activated by tonic background levels of extracellular GABA, and GABAC currents elicited by local GABA puffs, are both significantly enhanced by ascorbic acid. In addition, a significant rundown of GABA-puff evoked currents was observed in the absence of ascorbic acid. GABA-evoked Cl- currents mediated by homomeric ρ1 GABAC receptors expressed in Xenopus laevis oocytes were also potentiated by ascorbic acid in a concentration-dependent, stereospecific, reversible, and voltage-independent manner. Studies involving the chemical modification of sulfhydryl groups showed that the two cys-loop cysteines and histidine 141, all located in the ρ1 subunit extracellular domain, each play a key role in the modulation of GABAC receptors by ascorbic acid. Additionally, we show that retinal GABAA IPSCs and heterologously expressed GABAA receptor currents are similarly augmented by ascorbic acid. Our results suggest that ascorbic acid may act as an endogenous agent capable of potentiating GABAergic neurotransmission in the CNS. PMID:21715633

  7. Microtubule-associated protein tau in bovine retinal photoreceptor rod outer segments: comparison with brain tau.

    PubMed

    Yamazaki, Akio; Nishizawa, Yuji; Matsuura, Isao; Hayashi, Fumio; Usukura, Jiro; Bondarenko, Vladimir A

    2013-10-01

    Recent studies have suggested a possible involvement of abnormal tau in some retinal degenerative diseases. The common view in these studies is that these retinal diseases share the mechanism of tau-mediated degenerative diseases in brain and that information about these brain diseases may be directly applied to explain these retinal diseases. Here we collectively examine this view by revealing three basic characteristics of tau in the rod outer segment (ROS) of bovine retinal photoreceptors, i.e., its isoforms, its phosphorylation mode and its interaction with microtubules, and by comparing them with those of brain tau. We find that ROS contains at least four isoforms: three are identical to those in brain and one is unique in ROS. All ROS isoforms, like brain isoforms, are modified with multiple phosphate molecules; however, ROS isoforms show their own specific phosphorylation pattern, and these phosphorylation patterns appear not to be identical to those of brain tau. Interestingly, some ROS isoforms, under the normal conditions, are phosphorylated at the sites identical to those in Alzheimer's patient isoforms. Surprisingly, a large portion of ROS isoforms tightly associates with a membranous component(s) other than microtubules, and this association is independent of their phosphorylation states. These observations strongly suggest that tau plays various roles in ROS and that some of these functions may not be comparable to those of brain tau. We believe that knowledge about tau in the entire retinal network and/or its individual cells are also essential for elucidation of tau-mediated retinal diseases, if any. PMID:23712071

  8. Acute and Chronic Hyperglycemia Elicit JIP1/JNK-Mediated Endothelial Vasodilator Dysfunction of Retinal Arterioles

    PubMed Central

    Hein, Travis W.; Xu, Wenjuan; Xu, Xin; Kuo, Lih

    2016-01-01

    Purpose Hyperglycemia, a hallmark of diabetes mellitus, is associated with retinal inflammation and impairment of endothelium-dependent nitric oxide (NO)–mediated dilation of retinal arterioles. However, molecular mechanisms involved in this diminished endothelial vasodilator function remain unclear. We examined whether inflammatory stress-activated kinases, c-Jun N-terminal kinase (JNK) and p38, contribute to retinal arteriolar dysfunction during exposure to acute and chronic hyperglycemia. Methods Retinal arterioles were isolated from streptozocin-induced diabetic pigs (2 weeks; chronic hyperglycemia, 471 ± 23 mg/dL) or age-matched control pigs (euglycemia, 79 ± 5 mg/dL), and then cannulated and pressurized for vasoreactivity study. For acute hyperglycemia study, vessels from nondiabetic pigs were exposed intraluminally to high glucose (25 mM ≈ 450 mg/dL) for 2 hours, and normal glucose (5 mM ≈ 90 mg/dL) served as the control. Results Endothelium-dependent vasodilation to bradykinin was reduced in a similar manner after exposure to acute or chronic hyperglycemia. Administration of NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) nearly abolished vasodilations either in control (euglycemia and normal glucose) or hyperglycemic (acute and chronic) vessels. Treatment of either acute or chronic hyperglycemic vessels with JNK inhibitor SP600125 or JNK-interacting protein-1 (JIP1) inhibitor BI-78D3, but not p38 inhibitor SB203580, preserved bradykinin-induced dilation in an L-NAME–sensitive manner. By contrast, endothelium-independent vasodilation to sodium nitroprusside was unaffected by acute or chronic hyperglycemia. Conclusions Activation of JIP1/JNK signaling in retinal arterioles during exposure to acute or chronic hyperglycemia leads to selective impairment of endothelium-dependent NO-mediated dilation. Therapeutic targeting of the vascular JNK pathway may improve retinal endothelial vasodilator function during early diabetes. PMID

  9. Visual pattern discrimination by population retinal ganglion cells' activities during natural movie stimulation.

    PubMed

    Zhang, Ying-Ying; Wang, Ru-Bin; Pan, Xiao-Chuan; Gong, Hai-Qing; Liang, Pei-Ji

    2014-02-01

    In the visual system, neurons often fire in synchrony, and it is believed that synchronous activities of group neurons are more efficient than single cell response in transmitting neural signals to down-stream neurons. However, whether dynamic natural stimuli are encoded by dynamic spatiotemporal firing patterns of synchronous group neurons still needs to be investigated. In this paper we recorded the activities of population ganglion cells in bullfrog retina in response to time-varying natural images (natural scene movie) using multi-electrode arrays. In response to some different brief section pairs of the movie, synchronous groups of retinal ganglion cells (RGCs) fired with similar but different spike events. We attempted to discriminate the movie sections based on temporal firing patterns of single cells and spatiotemporal firing patterns of the synchronous groups of RGCs characterized by a measurement of subsequence distribution discrepancy. The discrimination performance was assessed by a classification method based on Support Vector Machines. Our results show that different movie sections of the natural movie elicited reliable dynamic spatiotemporal activity patterns of the synchronous RGCs, which are more efficient in discriminating different movie sections than the temporal patterns of the single cells' spike events. These results suggest that, during natural vision, the down-stream neurons may decode the visual information from the dynamic spatiotemporal patterns of the synchronous group of RGCs' activities. PMID:24465283

  10. Long-term outcomes in patients undergoing vitrectomy for retinal detachment due to viral retinitis

    PubMed Central

    Almeida, David RP; Chin, Eric K; Tarantola, Ryan M; Tegins, Elizabeth O; Lopez, Christopher A; Boldt, Herbert Culver; Gehrs, Karen M; Sohn, Elliott H; Russell, Stephen R; Folk, James C; Mahajan, Vinit B

    2015-01-01

    Purpose To determine the outcomes in patients with rhegmatogenous retinal detachment (RRD) secondary to viral retinitis. Patients and methods This was a retrospective, consecutive, noncomparative, interventional case series of 12 eyes in ten patients with RRD secondary to viral retinitis. Results of vitreous or aqueous biopsy, effect of antiviral therapeutics, time to retinal detachment, course of visual acuity, and anatomic and surgical outcomes were investigated. Results There were 1,259 cases of RRD during the study period, with 12 cases of RRD secondary to viral retinitis (prevalence of 0.95%). Follow-up was available for a mean period of 4.4 years. Varicella zoster virus was detected in six eyes, herpes simplex virus in two eyes, and cytomegalovirus in two eyes. Eight patients were treated with oral valacyclovir and two patients with intravenous acyclovir. Lack of optic nerve involvement correlated with improved final visual acuity of 20/100 or greater. Pars plana vitrectomy (n=12), silicone-oil tamponade (n=11), and scleral buckling (n=10) provided successful anatomic retinal reattachment in all cases, with no recurrent retinal detachment and no cases of hypotony during the follow-up period. Conclusion Varicella zoster virus was the most frequent cause of viral retinitis, and lack of optic nerve involvement was predictive of a favorable visual acuity prognosis. Vitrectomy with silicone-oil tamponade and scleral buckle placement provided stable anatomical outcomes. PMID:26229423

  11. Electroretinographic effects of retinal dragging and retinal folds in eyes with familial exudative vitreoretinopathy

    PubMed Central

    Yaguchi, Yukari; Katagiri, Satoshi; Fukushima, Yoko; Yokoi, Tadashi; Nishina, Sachiko; Kondo, Mineo; Azuma, Noriyuki

    2016-01-01

    We evaluated the retinal function of retinal dragging (Rdrag) and radial retinal folds (Rfolds) in eyes with familial exudative vitreoretinopathy (FEVR) using full-field electroretinography (ERG). Seventeen eyes of nine patients with FEVR who had Rdrag or Rfolds were retrospectively studied. Eyes were classified into four groups according to the severity of the retinal alterations: Group 1, without Rdrag or Rfolds (5 eyes); Group 2, with Rdrag (4 eyes); Group 3, with Rfolds (6 eyes); and Group 4, with Rfolds in which all major retinal vessels were involved (2 eyes). The amplitudes of all ERG components and the implicit times of the photopic a- and b-waves and 30-Hz flicker responses were decreased or prolonged as the severity of the retinal alterations increased (P < 0.01). The photopic negative response was most severely affected and nearly undetectable in all eyes in Groups 3 and 4, although the other ERG components were detectable in all eyes in Group 3 and one eye in Group 4. These results suggest the decrease of retinal functions was correlated with the degree of severity of Rdrag and Rfolds in eyes with FEVR. In addition, the function of the retinal ganglion cells appears to be more severely affected compared with the others. PMID:27456314

  12. School Fires. Topical Fire Research Series. Volume 8, Issue 1

    ERIC Educational Resources Information Center

    US Department of Homeland Security, 2007

    2007-01-01

    Using the past 3 years of data, for 2003 to 2005, from the National Fire Incident Reporting System (NFIRS) database, the yearly national fire loss for fires on nonadult school properties is estimated at $85 million. Such losses are the result of an estimated annual average of 14,700 fires that required a fire department response. Fires on school…

  13. Fire Service Training. Fire Stream Practices. (Revised).

    ERIC Educational Resources Information Center

    North Carolina State Dept. of Community Colleges, Raleigh.

    One of a set of fourteen instructional outlines for use in a course to train novice firemen, this guide covers the topic of fire streams. The various types of fire streams are identified as well as the methods used to produce them, emphasizing the operation of nozzles and the different kinds of friction loss. Designed to be used with the Robert J.…

  14. Fires Scorch Oregon

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On Wednesday, August 7, 2002, two large Oregon fires merged into a single massive fire of more than 333,000 acres. In southwest Oregon, the Sour Biscuit fire on the Oregon-California state line, and the larger Florence Fire to its north closed the gap between them and created an enormous blaze that retained the name Biscuit Fire. The fire has burned over the Oregon state line into California. This image of the fires and thick smoke was captured by the landsat 7 Enhanced Thematic Mapper Plus on August 14, 2002. In this false-color iamge, vegetation is green, burned areas are deep magenta, actively burning fire is bright pink, and smoke is blue. Credit:Image provided by the USGS EROS Data Center Satellite Systems Branch.

  15. FIRE Data and Information

    Atmospheric Science Data Center

    2015-11-13

    ... The First ISCCP Regional Experiment ( FIRE ) is a series of field missions which have collected cirrus and marine stratocumulus ... Marine Stratocumulus Home Page FIRE I - Extended Time Observations Home Page SCAR-B Block:  ...

  16. Wildland Fire Safety

    MedlinePlus

    Wildland Fire Safety Every year, wildfires burn across the U.S., and more and more people are living where wildfires ... including garages and sheds. If it can catch fire, don’t let it touch your house, deck ...

  17. South America Fire Observations

    NASA Video Gallery

    From space, we can understand fires in ways that are impossible from the ground. NASA research has contributed to much improved detection of fire for scientific purposes using satellite remote sens...

  18. Fire regimes of quaking aspen in the Mountain West

    USGS Publications Warehouse

    Shinneman, Douglas J.; Baker, William L.; Rogers, Paul C.; Kulakowski, Dominik

    2013-01-01

    settings and correlated aspen functional types. We propose the following aspen fire regime types: (1) fire-independent, stable aspen; (2) fire-influenced, stable aspen; (3) fire-dependent, seral, conifer-aspen mix; (4) fire-dependent, seral, montane aspen-conifer; and (5) fire-dependent, seral, subalpine aspen-conifer. Closing research gaps and validating our proposed aspen fire regime classification will likely require additional site-specific research, enhanced dendrochronology techniques, charcoal and pollen record analysis, spatially-explicit modeling, and other techniques. We hope to encourage development of site-appropriate disturbance ecology characterizations, in order to aid efforts to manage and restore aspen communities and to diagnose key factors contributing to changes in aspen.

  19. Light-Induced Retinal Changes Observed with High-Resolution Autofluorescence Imaging of the Retinal Pigment Epithelium

    PubMed Central

    Morgan, Jessica I. W.; Hunter, Jennifer J.; Masella, Benjamin; Wolfe, Robert; Gray, Daniel C.; Merigan, William H.; Delori, François C.; Williams, David R.

    2009-01-01

    Purpose Autofluorescence fundus imaging using an adaptive optics scanning laser ophthalmoscope (AOSLO) allows for imaging of individual retinal pigment epithelial (RPE) cells in vivo. In this study, the potential of retinal damage was investigated by using radiant exposure levels that are 2 to 150 times those used for routine imaging. Methods Macaque retinas were imaged in vivo with a fluorescence AOSLO. The retina was exposed to 568- or 830-nm light for 15 minutes at various intensities over a square ½° per side. Pre-and immediate postexposure images of the photoreceptors and RPE cells were taken over a 2° field. Long-term AOSLO imaging was performed intermittently from 5 to 165 days after exposure. Exposures delivered over a uniform field were also investigated. Results Exposures to 568-nm light caused an immediate decrease in autofluorescence of RPE cells. Follow-up imaging revealed either full recovery of autofluorescence or long-term damage in the RPE cells at the exposure. The outcomes of AOSLO exposures and uniform field exposures of equal average power were not significantly different. No effects from 830-nm exposures were observed. Conclusions The study revealed a novel change in RPE autofluorescence induced by 568-nm light exposure. Retinal damage occurred as a direct result of total average power, independent of the light-delivery method. Because the exposures were near or below permissible levels in laser safety standards, these results suggest that caution should be used with exposure of the retina to visible light and that the safety standards should be re-evaluated for these exposure conditions. PMID:18408191

  20. Hydrogen Fire Imager

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Through NASA's Technology Transfer Office at Stennis Space Center, two SSC engineers were able to market their hand-held fire imager. Called FIRESCAPE, the device allows firefighters to 'see' the invisible flames of hydrogen and alcohol fires in the daylight, as well as to find victims and burning embers in dense smoke and fog. SafetySCAN, which specializes in fire safety electronic products, will make the device the first affordable commercial product for fire imaging.

  1. Fire Education Planning.

    ERIC Educational Resources Information Center

    National Fire Prevention and Control Administration (DOC), Washington, DC.

    This curriculum guide for public fire educators was developed to assist them in planning and implementing fire educational programs for older Americans (over 65), adults, youthful firesetters, and children. This booklet's content is in four parts: (1) Over 65 and Fire Safety discusses five broad questions which provide the framework for planning…

  2. Fire Prevention Inspection Procedures.

    ERIC Educational Resources Information Center

    Pribyl, Paul F.

    Lesson plans are provided for a fire prevention inspection course of the Wisconsin Fire Service Training program. Objectives for the course are to enable students to describe and conduct fire prevention inspections, to identify and correct hazards common to most occupancies, to understand the types of building construction and occupancy, and to…

  3. Fire Prevention Education.

    ERIC Educational Resources Information Center

    Ehmann, Jeanne; Claus, William C.

    The fire prevention education bulletin helps schools continue their work to make the home, school, and community safe places in which to live and to help children and young people live in safe ways without developing undue fears. Briefly discussed are the goals of a fire prevention program, who should be concerned with fire prevention education,…

  4. Fire Department Emergency Response

    SciTech Connect

    Blanchard, A.; Bell, K.; Kelly, J.; Hudson, J.

    1997-09-01

    In 1995 the SRS Fire Department published the initial Operations Basis Document (OBD). This document was one of the first of its kind in the DOE complex and was widely distributed and reviewed. This plan described a multi-mission Fire Department which provided fire, emergency medical, hazardous material spill, and technical rescue services.

  5. Fire as Technology

    ERIC Educational Resources Information Center

    Rudolph, Robert N.

    2011-01-01

    In this article, the author describes a project that deals with fire production as an aspect of technology. The project challenges students to be survivors in a five-day classroom activity. Students research various materials and methods to produce fire without the use of matches or other modern combustion devices, then must create "fire" to keep…

  6. Alaska and Yukon Fires

    Atmospheric Science Data Center

    2014-05-15

    article title:  Smoke Signals from the Alaska and Yukon Fires   ... the Yukon Territory from mid-June to mid-July, 2004. Thick smoke particles filled the air during these fires, prompting Alaskan officials to issue air quality warnings. Some of the smoke from these fires was detected as far away as New Hampshire. These ...

  7. Fire Safety Fundamentals

    ERIC Educational Resources Information Center

    Roy, Ken

    2004-01-01

    Planning and prevention is the best defense against fires in school. This is particularly true in the science laboratory due to the presence of flammable gases, liquids, combustibles, and other potential sources of fire. Teachers can prevent fires from starting by maintaining prudent lab practices when dealing with combustible and flammable…

  8. Pharmacological approaches to retinitis pigmentosa: A laboratory perspective.

    PubMed

    Guadagni, Viviana; Novelli, Elena; Piano, Ilaria; Gargini, Claudia; Strettoi, Enrica

    2015-09-01

    Retinal photoreceptors are highly specialized and performing neurons. Their cellular architecture is exquisitely designed to host a high concentration of molecules involved in light capture, phototransduction, electric and chemical signaling, membrane and molecular turnover, light and dark adaption, network activities etc. Such high efficiency and molecular complexity require a great metabolic demand, altogether conferring to photoreceptors particular susceptibility to external and internal insults, whose occurrence usually precipitate into degeneration of these cells and blindness. In Retinitis Pigmentosa, an impressive number of mutations in genes expressed in the retina and coding for a large varieties of proteins leads to the progressive death of photoreceptors and blindness. Recent advances in molecular tools have greatly facilitated the identification of the underlying genetics and molecular bases of RP leading to the successful implementation of gene therapy for some types of mutations, with visual restoration in human patients. Yet, genetic heterogeneity of RP makes mutation-independent approaches highly desirable, although many obstacles pave the way to general strategies for treating this complex disease, which remains orphan. The review will focus on treatments for RP based on pharmacological tools, choosing, among the many ongoing studies, approaches which rely on strong experimental evidence or rationale. For perspective treatments, new concepts are foreseen to emerge from basic studies elucidating the pathways connecting the primary mutations to photoreceptor death, possibly revealing common molecular targets for drug intervention. PMID:26113212

  9. Adaptive optics optical coherence tomography with dynamic retinal tracking

    PubMed Central

    Kocaoglu, Omer P.; Ferguson, R. Daniel; Jonnal, Ravi S.; Liu, Zhuolin; Wang, Qiang; Hammer, Daniel X.; Miller, Donald T.

    2014-01-01

    Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction with strip-wise registration to independently measure AO-OCT tracking performance. After optimization of the tracker parameters, the system was found to correct eye movements up to 100 Hz and reduce residual motion to 10 µm root mean square. Between session precision was 33 µm. Performance was limited by tracker-generated noise at high temporal frequencies. PMID:25071963

  10. Chloroquine and Hydroxychloroquine Increase Retinal Pigment Epithelial Layer Permeability.

    PubMed

    Korthagen, Nicoline M; Bastiaans, Jeroen; van Meurs, Jan C; van Bilsen, Kiki; van Hagen, P Martin; Dik, Willem A

    2015-07-01

    Antimalarials chloroquine (CQ) and hydroxychloroquine (HCQ) are widely used as antiinflammatory drugs, but side effects include retinopathy and vision loss. The objective of this study was to examine the effect of CQ and HCQ on the barrier integrity of retinal pigment epithelial (RPE) cell monolayers in vitro. Permeability of ARPE-19 cell monolayers was determined using Fluorescein isothiocyanate (FITC)-labeled dextran. The influence of CQ and HCQ on cell death and the expression tight junction molecules was examined. CQ and HCQ significantly increased ARPE-19 monolayer permeability after 3 and 18 h, respectively, and enhanced mRNA levels for claudin-1 and occludin. Cytotoxicity was only observed after 18 h exposure. Thus, CQ and HCQ rapidly enhance RPE barrier permeability in vitro, independent of cytotoxicity or loss of zonula occludens-1, claudin-1, and occludin expression. Our findings suggest that CQ/HCQ-induced permeability of the RPE layer may contribute to blood-retinal barrier breakdown in case of CQ/HCQ-induced retinopathy. PMID:25752684

  11. Adaptive optics optical coherence tomography with dynamic retinal tracking.

    PubMed

    Kocaoglu, Omer P; Ferguson, R Daniel; Jonnal, Ravi S; Liu, Zhuolin; Wang, Qiang; Hammer, Daniel X; Miller, Donald T

    2014-07-01

    Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction with strip-wise registration to independently measure AO-OCT tracking performance. After optimization of the tracker parameters, the system was found to correct eye movements up to 100 Hz and reduce residual motion to 10 µm root mean square. Between session precision was 33 µm. Performance was limited by tracker-generated noise at high temporal frequencies. PMID:25071963

  12. ABCF1 extrinsically regulates retinal pigment epithelial cell phagocytosis

    PubMed Central

    Guo, Feiye; Ding, Ying; Caberoy, Nora; Alvarado, Gabriela; Wang, Feng; Chen, Rui; Li, Wei

    2015-01-01

    Phagocytosis of shed photoreceptor outer segments (POSs) by retinal pigment epithelial (RPE) cells is critical to retinal homeostasis and shares many conserved signaling pathways with other phagocytes, including extrinsic regulations. Phagocytotic ligands are the key to cargo recognition, engulfment initiation, and activity regulation. In this study, we identified intracellular protein ATP-binding cassette subfamily F member 1 (ABCF1) as a novel RPE phagocytotic ligand by a new approach of functional screening. ABCF1 was independently verified to extrinsically promote phagocytosis of shed POSs by D407 RPE cells. This finding was further corroborated with primary RPE cells and RPE explants. Internalized POS vesicles were colocalized with a phagosome marker, suggesting that ABCF1-mediated engulfment is through a phagocytic pathway. ABCF1 was released from apoptotic cells and selectively bound to shed POS vesicles and apoptotic cells, possibly via externalized phosphatidylserine. ABCF1 is predominantly expressed in POSs and colocalized with the POS marker rhodopsin, providing geographical convenience for regulation of RPE phagocytosis. Collectively these results suggest that ABCF1 is released from and binds to shed POSs in an autocrine manner to facilitate RPE phagocytosis through a conserved pathway. Furthermore, the new approach is broadly applicable to many other phagocytes and will enable systematic elucidation of their ligands to understand extrinsic regulation and cargo recognition. PMID:25904329

  13. Toward high-resolution optoelectronic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Palanker, Daniel; Huie, Philip; Vankov, Alexander; Asher, Alon; Baccus, Steven

    2005-04-01

    It has been already demonstrated that electrical stimulation of retina can produce visual percepts in blind patients suffering from macular degeneration and retinitis pigmentosa. Current retinal implants provide very low resolution (just a few electrodes), while several thousand pixels are required for functional restoration of sight. We present a design of the optoelectronic retinal prosthetic system that can activate a retinal stimulating array with pixel density up to 2,500 pix/mm2 (geometrically corresponding to a visual acuity of 20/80), and allows for natural eye scanning rather than scanning with a head-mounted camera. The system operates similarly to "virtual reality" imaging devices used in military and medical applications. An image from a video camera is projected by a goggle-mounted infrared LED-LCD display onto the retina, activating an array of powered photodiodes in the retinal implant. Such a system provides a broad field of vision by allowing for natural eye scanning. The goggles are transparent to visible light, thus allowing for simultaneous utilization of remaining natural vision along with prosthetic stimulation. Optical control of the implant allows for simple adjustment of image processing algorithms and for learning. A major prerequisite for high resolution stimulation is the proximity of neural cells to the stimulation sites. This can be achieved with sub-retinal implants constructed in a manner that directs migration of retinal cells to target areas. Two basic implant geometries are described: perforated membranes and protruding electrode arrays. Possibility of the tactile neural stimulation is also examined.

  14. Validation of Smartphone Based Retinal Photography for Diabetic Retinopathy Screening

    PubMed Central

    Rajalakshmi, Ramachandran; Arulmalar, Subramanian; Usha, Manoharan; Prathiba, Vijayaraghavan; Kareemuddin, Khaji Syed; Anjana, Ranjit Mohan; Mohan, Viswanathan

    2015-01-01

    Aim To evaluate the sensitivity and specificity of “fundus on phone’ (FOP) camera, a smartphone based retinal imaging system, as a screening tool for diabetic retinopathy (DR) detection and DR severity in comparison with 7-standard field digital retinal photography. Design Single-site, prospective, comparative, instrument validation study. Methods 301 patients (602 eyes) with type 2 diabetes underwent standard seven-field digital fundus photography with both Carl Zeiss fundus camera and indigenous FOP at a tertiary care diabetes centre in South India. Grading of DR was performed by two independent retina specialists using modified Early Treatment of Diabetic Retinopathy Study grading system. Sight threatening DR (STDR) was defined by the presence of proliferative DR(PDR) or diabetic macular edema. The sensitivity, specificity and image quality were assessed. Results The mean age of the participants was 53.5 ±9.6 years and mean duration of diabetes 12.5±7.3 years. The Zeiss camera showed that 43.9% had non-proliferative DR(NPDR) and 15.3% had PDR while the FOP camera showed that 40.2% had NPDR and 15.3% had PDR. The sensitivity and specificity for detecting any DR by FOP was 92.7% (95%CI 87.8–96.1) and 98.4% (95%CI 94.3–99.8) respectively and the kappa (ĸ) agreement was 0.90 (95%CI-0.85–0.95 p<0.001) while for STDR, the sensitivity was 87.9% (95%CI 83.2–92.9), specificity 94.9% (95%CI 89.7–98.2) and ĸ agreement was 0.80 (95%CI 0.71–0.89 p<0.001), compared to conventional photography. Conclusion Retinal photography using FOP camera is effective for screening and diagnosis of DR and STDR with high sensitivity and specificity and has substantial agreement with conventional retinal photography. PMID:26401839

  15. Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment

    PubMed Central

    Wilkinson, Charles P

    2015-01-01

    Background Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina in the region of the retinal break, because such symptomatic retinal tears are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these lesions frequently is recommended, in spite of the fact that the effectiveness of this therapy is unproven. Objectives The objective of this review was to assess the effectiveness and safety of techniques used to treat asymptomatic retinal breaks and lattice degeneration for the prevention of retinal detachment. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 2), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to February 2014), EMBASE (January 1980 to February 2014), PubMed (January 1948 to February 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in

  16. Differential Modulation of Retinal Degeneration by Ccl2 and Cx3cr1 Chemokine Signalling

    PubMed Central

    Luhmann, Ulrich F. O.; Lange, Clemens A.; Robbie, Scott; Munro, Peter M. G.; Cowing, Jill A.; Armer, Hannah E. J.; Luong, Vy; Carvalho, Livia S.; MacLaren, Robert E.; Fitzke, Frederick W.; Bainbridge, James W. B.; Ali, Robin R.

    2012-01-01

    Microglia and macrophages are recruited to sites of retinal degeneration where local cytokines and chemokines determine protective or neurotoxic microglia responses. Defining the role of Ccl2-Ccr2 and Cx3cl1-Cx3cr1 signalling for retinal pathology is of particular interest because of its potential role in age-related macular degeneration (AMD). Ccl2, Ccr2, and Cx3cr1 signalling defects impair macrophage trafficking, but have, in several conflicting studies, been reported to show different degrees of age-related retinal degeneration. Ccl2/Cx3cr1 double knockout (CCDKO) mice show an early onset retinal degeneration and have been suggested as a model for AMD. In order to understand phenotypic discrepancies in different chemokine knockout lines and to study how defects in Ccl2 and/or Cx3cr1 signalling contribute to the described early onset retinal degeneration, we defined primary and secondary pathological events in CCDKO mice. To control for genetic background variability, we compared the original phenotype with that of single Ccl2, Cx3cr1 and Ccl2/Cx3cr1 double knockout mice obtained from backcrosses of CCDKO with C57Bl/6 mice. We found that the primary pathological event in CCDKO mice develops in the inferior outer nuclear layer independently of light around postnatal day P14. RPE and vascular lesions develop secondarily with increasing penetrance with age and are clinically similar to retinal telangiectasia not to choroidal neovascularisation. Furthermore, we provide evidence that a third autosomal recessive gene causes the degeneration in CCDKO mice and in all affected re-derived lines and subsequently demonstrated co-segregation of the naturally occurring RD8 mutation in the Crb1 gene. By comparing CCDKO mice with re-derived CCl2−/−/Crb1Rd8/RD8, Cx3cr1−/−/Crb1Rd8/RD8 and CCl2−/−/Cx3cr1−/−/Crb1Rd8/RD8 mice, we observed a differential modulation of the retinal phenotype by genetic background and both chemokine signalling pathways. These findings

  17. Amyloidosis in Retinal Neurodegenerative Diseases.

    PubMed

    Masuzzo, Ambra; Dinet, Virginie; Cavanagh, Chelsea; Mascarelli, Frederic; Krantic, Slavica

    2016-01-01

    As a part of the central nervous system, the retina may reflect both physiological processes and abnormalities related to pathologies that affect the brain. Amyloidosis due to the accumulation of amyloid-beta (Aβ) was initially regarded as a specific and exclusive characteristic of neurodegenerative alterations seen in the brain of Alzheimer's disease (AD) patients. More recently, it was discovered that amyloidosis-related alterations, similar to those seen in the brain of Alzheimer's patients, also occur in the retina. Remarkably, these alterations were identified not only in primary retinal pathologies, such as age-related macular degeneration (AMD) and glaucoma, but also in the retinas of Alzheimer's patients. In this review, we first briefly discuss the biogenesis of Aβ, a peptide involved in amyloidosis. We then discuss some pathological aspects (synaptic dysfunction, mitochondrial failure, glial activation, and vascular abnormalities) related to the neurotoxic effects of Aβ. We finally highlight common features shared by AD, AMD, and glaucoma in the context of Aβ amyloidosis and further discuss why the retina, due to the transparency of the eye, can be considered as a "window" to the brain. PMID:27551275

  18. Evolution of vertebrate retinal photoreception

    PubMed Central

    Lamb, Trevor D.

    2009-01-01

    Recent findings shed light on the steps underlying the evolution of vertebrate photoreceptors and retina. Vertebrate ciliary photoreceptors are not as wholly distinct from invertebrate rhabdomeric photoreceptors as is sometimes thought. Recent information on the phylogenies of ciliary and rhabdomeric opsins has helped in constructing the likely routes followed during evolution. Clues to the factors that led the early vertebrate retina to become invaginated can be obtained by combining recent knowledge about the origin of the pathway for dark re-isomerization of retinoids with knowledge of the inability of ciliary opsins to undergo photoreversal, along with consideration of the constraints imposed under the very low light levels in the deep ocean. Investigation of the origin of cell classes in the vertebrate retina provides support for the notion that cones, rods and bipolar cells all originated from a primordial ciliary photoreceptor, whereas ganglion cells, amacrine cells and horizontal cells all originated from rhabdomeric photoreceptors. Knowledge of the molecular differences between cones and rods, together with knowledge of the scotopic signalling pathway, provides an understanding of the evolution of rods and of the rods' retinal circuitry. Accordingly, it has been possible to propose a plausible scenario for the sequence of evolutionary steps that led to the emergence of vertebrate photoreceptors and retina. PMID:19720653

  19. Multi-MHz retinal OCT

    PubMed Central

    Klein, Thomas; Wieser, Wolfgang; Reznicek, Lukas; Neubauer, Aljoscha; Kampik, Anselm; Huber, Robert

    2013-01-01

    We analyze the benefits and problems of in vivo optical coherence tomography (OCT) imaging of the human retina at A-scan rates in excess of 1 MHz, using a 1050 nm Fourier-domain mode-locked (FDML) laser. Different scanning strategies enabled by MHz OCT line rates are investigated, and a simple multi-volume data processing approach is presented. In-vivo OCT of the human ocular fundus is performed at different axial scan rates of up to 6.7 MHz. High quality non-mydriatic retinal imaging over an ultra-wide field is achieved by a combination of several key improvements compared to previous setups. For the FDML laser, long coherence lengths and 72 nm wavelength tuning range are achieved using a chirped fiber Bragg grating in a laser cavity at 419.1 kHz fundamental tuning rate. Very large data sets can be acquired with sustained data transfer from the data acquisition card to host computer memory, enabling high-quality averaging of many frames and of multiple aligned data sets. Three imaging modes are investigated: Alignment and averaging of 24 data sets at 1.68 MHz axial line rate, ultra-dense transverse sampling at 3.35 MHz line rate, and dual-beam imaging with two laser spots on the retina at an effective line rate of 6.7 MHz. PMID:24156052

  20. Amyloidosis in Retinal Neurodegenerative Diseases

    PubMed Central

    Masuzzo, Ambra; Dinet, Virginie; Cavanagh, Chelsea; Mascarelli, Frederic; Krantic, Slavica

    2016-01-01

    As a part of the central nervous system, the retina may reflect both physiological processes and abnormalities related to pathologies that affect the brain. Amyloidosis due to the accumulation of amyloid-beta (Aβ) was initially regarded as a specific and exclusive characteristic of neurodegenerative alterations seen in the brain of Alzheimer’s disease (AD) patients. More recently, it was discovered that amyloidosis-related alterations, similar to those seen in the brain of Alzheimer’s patients, also occur in the retina. Remarkably, these alterations were identified not only in primary retinal pathologies, such as age-related macular degeneration (AMD) and glaucoma, but also in the retinas of Alzheimer’s patients. In this review, we first briefly discuss the biogenesis of Aβ, a peptide involved in amyloidosis. We then discuss some pathological aspects (synaptic dysfunction, mitochondrial failure, glial activation, and vascular abnormalities) related to the neurotoxic effects of Aβ. We finally highlight common features shared by AD, AMD, and glaucoma in the context of Aβ amyloidosis and further discuss why the retina, due to the transparency of the eye, can be considered as a “window” to the brain. PMID:27551275

  1. Fighting Forest Fires

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Firefly is an airborne system for imaging forest fires. It uses satellite-based navigation for greater positioning accuracy and offers timeliness in fire location data delivery with on board data processing and a direct aircraft-to-fire camp communications link. Developed by Jet Propulsion Laboratory and the USFS, it has an infrared line scanner to identify fire boundaries and an infrared sensor system that can penetrate smoke to image the ground. Firefly is an outgrowth of a previous collaboration that produced FLAME, an airborne fire mapping instrument. Further refinements are anticipated by NASA and the United States Forest Service (USFS).

  2. Aircraft fire safety research

    NASA Technical Reports Server (NTRS)

    Botteri, Benito P.

    1987-01-01

    During the past 15 years, very significant progress has been made toward enhancing aircraft fire safety in both normal and hostile (combat) operational environments. Most of the major aspects of the aircraft fire safety problem are touched upon here. The technology of aircraft fire protection, although not directly applicable in all cases to spacecraft fire scenarios, nevertheless does provide a solid foundation to build upon. This is particularly true of the extensive research and testing pertaining to aircraft interior fire safety and to onboard inert gas generation systems, both of which are still active areas of investigation.

  3. Fire Protection Program Manual

    SciTech Connect

    Sharry, J A

    2012-05-18

    This manual documents the Lawrence Livermore National Laboratory (LLNL) Fire Protection Program. Department of Energy (DOE) Orders 420.1B, Facility Safety, requires LLNL to have a comprehensive and effective fire protection program that protects LLNL personnel and property, the public and the environment. The manual provides LLNL and its facilities with general information and guidance for meeting DOE 420.1B requirements. The recommended readers for this manual are: fire protection officers, fire protection engineers, fire fighters, facility managers, directorage assurance managers, facility coordinators, and ES and H team members.

  4. Evaluation and management of pediatric rhegmatogenous retinal detachment

    PubMed Central

    Wenick, Adam S.; Barañano, David E.

    2012-01-01

    Pediatric rhegmatogenous retinal detachments are rare, accounting for less than ten percent of all rhegmatogenous retinal detachments. While most retinal detachments in the adult population are related to posterior vitreous detachment, pediatric retinal detachment are often related to trauma or an underlying congenital abnormalities or genetic syndrome. The anatomy of pediatric eyes, the often late presentation of the disease, and the high incidence of bilateral pathology in children all pose significant challenges in the management of these patients. We discuss the epidemiology of pediatric rhegmatogenous retinal detachment, review the genetic syndromes associated with a high incidence of retinal detachment, and examine other common causes of retinal detachment in this age group. We then outline an approach to evaluation and management and describe the expected outcomes of repair of retinal detachment in the pediatric population. PMID:23961003

  5. Retinal imaging with virtual reality stimulus for studying Salticidae retinas

    NASA Astrophysics Data System (ADS)

    Schiesser, Eric; Canavesi, Cristina; Long, Skye; Jakob, Elizabeth; Rolland, Jannick P.

    2014-12-01

    We present a 3-path optical system for studying the retinal movement of jumping spiders: a visible OLED virtual reality system presents stimulus, while NIR illumination and imaging systems observe retinal movement.

  6. Rank Order Coding: a Retinal Information Decoding Strategy Revealed by Large-Scale Multielectrode Array Retinal Recordings123

    PubMed Central

    Maccione, Alessandro; Di Marco, Stefano; Kornprobst, Pierre

    2016-01-01

    How a population of retinal ganglion cells (RGCs) encodes the visual scene remains an open question. Going beyond individual RGC coding strategies, results in salamander suggest that the relative latencies of a RGC pair encode spatial information. Thus, a population code based on this concerted spiking could be a powerful mechanism to transmit visual information rapidly and efficiently. Here, we tested this hypothesis in mouse by recording simultaneous light-evoked responses from hundreds of RGCs, at pan-retinal level, using a new generation of large-scale, high-density multielectrode array consisting of 4096 electrodes. Interestingly, we did not find any RGCs exhibiting a clear latency tuning to the stimuli, suggesting that in mouse, individual RGC pairs may not provide sufficient information. We show that a significant amount of information is encoded synergistically in the concerted spiking of large RGC populations. Thus, the RGC population response described with relative activities, or ranks, provides more relevant information than classical independent spike count- or latency- based codes. In particular, we report for the first time that when considering the relative activities across the whole population, the wave of first stimulus-evoked spikes is an accurate indicator of stimulus content. We show that this coding strategy coexists with classical neural codes, and that it is more efficient and faster. Overall, these novel observations suggest that already at the level of the retina, concerted spiking provides a reliable and fast strategy to rapidly transmit new visual scenes. PMID:27275008

  7. Rank Order Coding: a Retinal Information Decoding Strategy Revealed by Large-Scale Multielectrode Array Retinal Recordings.

    PubMed

    Portelli, Geoffrey; Barrett, John M; Hilgen, Gerrit; Masquelier, Timothée; Maccione, Alessandro; Di Marco, Stefano; Berdondini, Luca; Kornprobst, Pierre; Sernagor, Evelyne

    2016-01-01

    How a population of retinal ganglion cells (RGCs) encodes the visual scene remains an open question. Going beyond individual RGC coding strategies, results in salamander suggest that the relative latencies of a RGC pair encode spatial information. Thus, a population code based on this concerted spiking could be a powerful mechanism to transmit visual information rapidly and efficiently. Here, we tested this hypothesis in mouse by recording simultaneous light-evoked responses from hundreds of RGCs, at pan-retinal level, using a new generation of large-scale, high-density multielectrode array consisting of 4096 electrodes. Interestingly, we did not find any RGCs exhibiting a clear latency tuning to the stimuli, suggesting that in mouse, individual RGC pairs may not provide sufficient information. We show that a significant amount of information is encoded synergistically in the concerted spiking of large RGC populations. Thus, the RGC population response described with relative activities, or ranks, provides more relevant information than classical independent spike count- or latency- based codes. In particular, we report for the first time that when considering the relative activities across the whole population, the wave of first stimulus-evoked spikes is an accurate indicator of stimulus content. We show that this coding strategy coexists with classical neural codes, and that it is more efficient and faster. Overall, these novel observations suggest that already at the level of the retina, concerted spiking provides a reliable and fast strategy to rapidly transmit new visual scenes. PMID:27275008

  8. Four-wavelength retinal vessel oximetry

    NASA Astrophysics Data System (ADS)

    Drewes, Jonathan Jensen

    1999-11-01

    This dissertation documents the design and construction of a four-wavelength retinal vessel oximeter, the Eye Oximeter (EOX). The EOX scans low-powered laser beams (at 629, 678, 821 and 899 nm) into the eye and across a targeted retinal vessel to measure the transmittance of the blood within the vessel. From the transmittance measurements, the oxygen saturation of the blood within the vessel is computed. Retinal vessel oxygen saturation has been suggested as a useful parameter for monitoring a wide range of conditions including occult blood loss and a variety of ophthalmic diseases. An artificial eye that simulates the geometry of a human retinal vessel was constructed and used to calibrate the EOX saturation measurement. A number of different oximetry equations were developed and tested. From measurements made on whole human blood in the artificial eye, an oximetry equation that places a linear wavelength dependance on the scattering losses (3% decrease from 629 to 899 nm) is found to best calibrate the EOX oxygen saturation measurement. This calibration also requires that an adjustment be made to the absorption coefficient of hemoglobin at 629 nm that has been reported in the literature. More than 4,000 measurements were made in the eyes of three human subjects during the development of the EOX. Applying the oximetry equation developed through the in vitro experiments to human data, the average human retinal venous oxygen saturation is estimated to be 0.63 +/- 0.07 and the average human retinal arterial oxygen saturation is 0.99 +/- 0.03. Furthermore, measurements made away from the optic disk resulted in a larger variance in the calculated saturation when compared to measurements made on the optic disk. A series of EOX experiments using anesthetized swine helped to verify the sensitivity of the EOX measurement of oxygen saturation. It is found that the calibration in swine differed from the calibration in the artificial eye. An empirical calibration from the

  9. Global Ca2+ Signaling Drives Ribbon-Independent Synaptic Transmission at Rod Bipolar Cell Synapses

    PubMed Central

    Mehta, Bhupesh; Ke, Jiang-Bin; Zhang, Lei; Baden, Alexander D.; Markowitz, Alexander L.; Nayak, Subhashree; Briggman, Kevin L.

    2014-01-01

    Ribbon-type presynaptic active zones are a hallmark of excitatory retinal synapses, and the ribbon organelle is thought to serve as the organizing point of the presynaptic active zone. Imaging of exocytosis from isolated retinal neurons, however, has revealed ectopic release (i.e., release away from ribbons) in significant quantities. Here, we demonstrate in an in vitro mouse retinal slice preparation that ribbon-independent release from rod bipolar cells activates postsynaptic AMPARs on AII amacrine cells. This form of release appears to draw on a unique, ribbon-independent, vesicle pool. Experimental, anatomical, and computational analyses indicate that it is elicited by a significant, global elevation of intraterminal [Ca2+] arising following local buffer saturation. Our observations support the conclusion that ribbon-independent release provides a read-out of the average behavior of all of the active zones in a rod bipolar cell's terminal. PMID:24790194

  10. Global Ca2+ signaling drives ribbon-independent synaptic transmission at rod bipolar cell synapses.

    PubMed

    Mehta, Bhupesh; Ke, Jiang-Bin; Zhang, Lei; Baden, Alexander D; Markowitz, Alexander L; Nayak, Subhashree; Briggman, Kevin L; Zenisek, David; Singer, Joshua H

    2014-04-30

    Ribbon-type presynaptic active zones are a hallmark of excitatory retinal synapses, and the ribbon organelle is thought to serve as the organizing point of the presynaptic active zone. Imaging of exocytosis from isolated retinal neurons, however, has revealed ectopic release (i.e., release away from ribbons) in significant quantities. Here, we demonstrate in an in vitro mouse retinal slice preparation that ribbon-independent release from rod bipolar cells activates postsynaptic AMPARs on AII amacrine cells. This form of release appears to draw on a unique, ribbon-independent, vesicle pool. Experimental, anatomical, and computational analyses indicate that it is elicited by a significant, global elevation of intraterminal [Ca(2+)] arising following local buffer saturation. Our observations support the conclusion that ribbon-independent release provides a read-out of the average behavior of all of the active zones in a rod bipolar cell's terminal. PMID:24790194

  11. Altered map of visual space in the superior colliculus of mice lacking early retinal waves.

    PubMed

    Mrsic-Flogel, Thomas D; Hofer, Sonja B; Creutzfeldt, Claire; Cloëz-Tayarani, Isabelle; Changeux, Jean-Pierre; Bonhoeffer, Tobias; Hübener, Mark

    2005-07-20

    During the development of the mammalian retinocollicular projection, a coarse retinotopic map is set up by the graded distribution of axon guidance molecules. Subsequent refinement of the initially diffuse projection has been shown to depend on the spatially correlated firing of retinal ganglion cells. In this scheme, the abolition of patterned retinal activity is not expected to influence overall retinotopic organization, but this has not been investigated. We used optical imaging of intrinsic signals to visualize the complete retinotopic map in the superior colliculus (SC) of mice lacking early retinal waves, caused by the deletion of the beta2 subunit of the nicotinic acetylcholine receptor. As expected from previous anatomical studies in the SC of beta2(-/-) mice, regions activated by individual visual stimuli were much larger and had less sharp borders than those in wild-type mice. Importantly, however, we also found systematic distortions of the entire retinotopic map: the map of visual space was expanded anteriorly and compressed posteriorly. Thus, patterned neuronal activity in the early retina has a substantial influence on the coarse retinotopic organization of the SC. PMID:16033902

  12. Jules Gonin. Pioneer of retinal detachment surgery.

    PubMed

    Wolfensberger, Thomas J

    2003-12-01

    Before the turn of the 20th century, eyes with a retinal detachment were considered doomed. Contrary to other branches of ophthalmology, such as cataract extraction, the surgical treatment of retinal detachment was still in its infancy, and the surgical success rates were less than five percent. From 1902 to 1921 Jules Gonin almost single handedly changed the landscape of retinal detachment surgery forever. He recognised that the retinal break was the cause--and not the consequence as it was largely believed at the time--of the retinal detachment, and that the treatment had at all costs to comprise the closure of the break by cauterisation. He named the procedure ignipuncture, as he cauterised the retina through the sclera with a very hot pointed instrument. Despite rigorously detailed clinical observations and increasing success rates, his discovery was not readily accepted and sometimes openly opposed by a large part of the ophthalmic establishment. It was not until 1929 that he received worldwide acclaim at the International Ophthalmological Congress in Amsterdam for his surgical technique. His legacy lives on in the eye hospital in Lausanne that bears his name, in the Gonin Medal awarded by the International Council of Ophthalmology every four years for the highest achievement in ophthalmology, and in a street named after him, the very street that he used to walk from his home to the hospital every day. PMID:14750617

  13. Retinal neurodegeneration may precede microvascular changes characteristic of diabetic retinopathy in diabetes mellitus.

    PubMed

    Sohn, Elliott H; van Dijk, Hille W; Jiao, Chunhua; Kok, Pauline H B; Jeong, Woojin; Demirkaya, Nazli; Garmager, Allison; Wit, Ferdinand; Kucukevcilioglu, Murat; van Velthoven, Mirjam E J; DeVries, J Hans; Mullins, Robert F; Kuehn, Markus H; Schlingemann, Reinier Otto; Sonka, Milan; Verbraak, Frank D; Abràmoff, Michael David

    2016-05-10

    Diabetic retinopathy (DR) has long been recognized as a microvasculopathy, but retinal diabetic neuropathy (RDN), characterized by inner retinal neurodegeneration, also occurs in people with diabetes mellitus (DM). We report that in 45 people with DM and no to minimal DR there was significant, progressive loss of the nerve fiber layer (NFL) (0.25 μm/y) and the ganglion cell (GC)/inner plexiform layer (0.29 μm/y) on optical coherence tomography analysis (OCT) over a 4-y period, independent of glycated hemoglobin, age, and sex. The NFL was significantly thinner (17.3 μm) in the eyes of six donors with DM than in the eyes of six similarly aged control donors (30.4 μm), although retinal capillary density did not differ in the two groups. We confirmed significant, progressive inner retinal thinning in streptozotocin-induced "type 1" and B6.BKS(D)-Lepr(db)/J "type 2" diabetic mouse models on OCT; immunohistochemistry in type 1 mice showed GC loss but no difference in pericyte density or acellular capillaries. The results suggest that RDN may precede the established clinical and morphometric vascular changes caused by DM and represent a paradigm shift in our understanding of ocular diabetic complications. PMID:27114552

  14. Retinal Vessel Caliber, Choroidal Thickness and Ocular Pulse Amplitude Measurements in Essential Thrombocythemia

    PubMed Central

    Pekel, Gökhan; Doğu, Mehmet Hilmi; Sarı, Hakan Ismail; Acer, Semra; Kasikci, Alper; Yagci, Ramazan; Çetin, Ebru Nevin

    2016-01-01

    Purpose: The choroid and retina receive most of the blood that enter to the eye, and this uptake may be affected by essential thrombocythemia (ET) in which thrombosis and hemorrhage is common. This study compares choroidal thickness, retinal vascular caliber, and ocular pulse amplitude (OPA) measurements between patients with ET and healthy adults. Materials and Methods: Thirty-seven patients with ET and 37 age-sex-matched healthy adults were recruited in this cross-sectional and comparative study. Spectral-domain optical coherence tomography was used to measure the subfoveal choroidal thickness (SFCT) and retinal vascular caliber measurements. The Pascal dynamic contour tonometer was used for OPA and intraocular pressure (IOP) measurements. The independent samples t-test was used for comparison of measurements between the groups. Pearson's correlation coefficient analysis was used to detect correlations between the variables. A P < 0.05 was statistically significant. Results: SFCT, OPA, and IOP measurements were not statistically significant differences between the study group and the control group (P > 0.05, all comparisons). Blood platelet counts were not associated with choroidal thickness, OPA, and IOP (P > 0.05). Retinal arteriolar and venular calibers were statistically, significantly thicker in healthy controls when compared to the study group (P < 0.05). Conclusions: Our results indicate that choroidal thickness and pulsatile blood flow are not significantly affected in ET and under high blood platelet counts. Retinal arteriolar and venular calibers are thinner in ET when compared to age-sex matched healthy controls. PMID:26957845

  15. Fire frequency in the Interior Columbia River Basin: Building regional models from fire history data

    USGS Publications Warehouse

    McKenzie, D.; Peterson, D.L.; Agee, James K.

    2000-01-01

    qualitative and quantitative methods when requisite data for fully quantitative models are unavailable. They can be tested by comparing new, independent fire history reconstructions against their predictions and can be continually updated, as better fire history data become available.

  16. Low Vision Rehabilitation of Retinitis Pigmentosa. Practice Report

    ERIC Educational Resources Information Center

    Rundquist, John

    2004-01-01

    Retinitis pigmentosa is a rod-cone dystrophy, commonly genetic in nature. Approximately 60-80% of those with retinitis pigmentosa inherit it by an autosomal recessive transmission (Brilliant, 1999). There have been some reported cases with no known family history. The symptoms of retinitis pigmentosa are decreased acuity, photophobia, night…

  17. Retinas in a Dish Peek into Inherited Retinal Degeneration.

    PubMed

    Duong, Thu T; Vasireddy, Vidyullatha; Mills, Jason A; Bennett, Jean

    2016-06-01

    Human retinal degeneration can cause blindness, and the lack of relevant model systems has made identifying underlying mechanisms challenging. Parfitt et al. (2016) generate three-dimensional retinal tissue from patient-derived induced pluripotent stem cells to identify how CEP290 mutations cause retinal degeneration, and show an antisense approach can correct disease-associated phenotypes. PMID:27257755

  18. Acute Variations in Retinal Vascular Oxygen Content in a Rabbit Model of Retinal Venous Occlusion

    PubMed Central

    Saati, Saloomeh; Martin, Gabriel; Chader, Gerald; Humayun, Mark S.

    2012-01-01

    Purpose To study the variation in intravascular oxygen saturation (oximetry) during an acute retinal vein occlusion (RVO) using hyperspectral computed tomographic spectroscopy based oximetry measurements. Methods Thirty rabbits were dilated and anesthetized for experiments. Baseline oximetry measurements were made using a custom-made hyperspectral computed tomographic imaging spectrometer coupled to a fundus camera. RVO were induced using argon green laser following an intravenous injection of Rose Bengal. RVO induction was confirmed by fluorescein angiography. Retinal oximetry measurements were repeated in arterial and venous branches one hour after RVO induction and up to 4 weeks afterwards. Comparison of retinal oximetry before and after vein occlusion was made using the Student T-test. Results One hour after RVO induction, we observed statistically significant reductions in the intravascular oxygen saturation in temporal retinal arteries (85.1±6.1% vs. 80.6±6.6%; p<0.0001) and veins (71.4±5.5% vs. 64.0±4.7%; p<0.0001). This decrease was reversible in animals that spontaneously recannulated the vein occlusion. There were no statistically significant differences in oxygen saturation in the nasal control arteries and veins before and after temporal vein RVO induction. Conclusions We demonstrate, for the first time, acute changes in the intravascular oxygen content of retinal vessels 1 hour after RVO. These changes are reversible upon spontaneous recannulation of retinal vessels. This study demonstrates that hyperspectral computer tomographic spectroscopy based oximetry can detect physiological variations in intravascular retinal oxygen saturation. The study also provides the first qualitative and quantitative evidence of the variation in retinal vascular oxygen content directly attributable to an acute retinal vein occlusion. PMID:23185567

  19. Repetitive magnetic stimulation improves retinal function in a rat model of retinal dystrophy

    NASA Astrophysics Data System (ADS)

    Rotenstreich, Ygal; Tzameret, Adi; Levi, Nir; Kalish, Sapir; Sher, Ifat; Zangen, Avraham; Belkin, Michael

    2014-02-01

    Vision incapacitation and blindness associated with retinal dystrophies affect millions of people worldwide. Retinal degeneration is characterized by photoreceptor cell death and concomitant remodeling of remaining retinal cells. Repetitive Magnetic Stimulation (RMS) is a non-invasive technique that creates alternating magnetic fields by brief electric currents transmitted through an insulated coil. These magnetic field generate action potentials in neurons, and modulate the expression of neurotransmitter receptors, growth factors and transcription factors which mediate plasticity. This technology has been proven effective and safe in various psychiatric disorders. Here we determined the effect of RMS on retinal function in Royal College of Surgeons (RCS) rats, a model for retinal dystrophy. Four week-old RCS and control Spargue Dawley (SD) rats received sham or RMS treatment over the right eye (12 sessions on 4 weeks). RMS treatment at intensity of at 40% of the maximal output of a Rapid2 stimulator significantly increased the electroretinogram (ERG) b-wave responses by up to 6- or 10-fold in the left and right eye respectively, 3-5 weeks following end of treatment. RMS treatment at intensity of 25% of the maximal output did not significant effect b-wave responses following end of treatment with no adverse effect on ERG response or retinal structure of SD rats. Our findings suggest that RMS treatment induces delayed improvement of retinal functions and may induce plasticity in the retinal tissue. Furthermore, this non-invasive treatment may possibly be used in the future as a primary or adjuvant treatment for retinal dystrophy.

  20. Inferior retinal light exposure is more effective than superior retinal exposure in suppressing melatonin in humans

    NASA Technical Reports Server (NTRS)

    Glickman, Gena; Hanifin, John P.; Rollag, Mark D.; Wang, Jenny; Cooper, Howard; Brainard, George C.

    2003-01-01

    Illumination of different areas of the human retina elicits differences in acute light-induced suppression of melatonin. The aim of this study was to compare changes in plasma melatonin levels when light exposures of equal illuminance and equal photon dose were administered to superior, inferior, and full retinal fields. Nine healthy subjects participated in the study. Plexiglass eye shields were modified to permit selective exposure of the superior and inferior halves of the retinas of each subject. The Humphrey Visual Field Analyzer was used both to confirm intact full visual fields and to quantify exposure of upper and lower visual fields. On study nights, eyes were dilated, and subjects were exposed to patternless white light for 90 min between 0200 and 0330 under five conditions: (1) full retinal exposure at 200 lux, (2) full retinal exposure at 100 lux, (3) inferior retinal exposure at 200 lux, (4) superior retinal exposure at 200 lux, and (5) a dark-exposed control. Plasma melatonin levels were determined by radioimmunoassay. ANOVA demonstrated a significant effect of exposure condition (F = 5.91, p < 0.005). Post hoc Fisher PLSD tests showed significant (p < 0.05) melatonin suppression of both full retinal exposures as well as the inferior retinal exposure; however, superior retinal exposure was significantly less effective in suppressing melatonin. Furthermore, suppression with superior retinal exposure was not significantly different from that of the dark control condition. The results indicate that the inferior retina contributes more to the light-induced suppression of melatonin than the superior retina at the photon dosages tested in this study. Findings suggest a greater sensitivity or denser distribution of photoreceptors in the inferior retina are involved in light detection for the retinohypothalamic tract of humans.

  1. Wavelength dependence of the apparent diameter of retinal blood vessels.

    PubMed

    Park, Robert; Twietmeyer, Karen; Chipman, Russell; Beaudry, Neil; Salyer, David

    2005-04-01

    Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column. PMID:15813519

  2. Automated retinal layer segmentation and characterization

    NASA Astrophysics Data System (ADS)

    Luisi, Jonathan; Briley, David; Boretsky, Adam; Motamedi, Massoud

    2014-05-01

    Spectral Domain Optical Coherence Tomography (SD-OCT) is a valuable diagnostic tool in both clinical and research settings. The depth-resolved intensity profiles generated by light backscattered from discrete layers of the retina provide a non-invasive method of investigating progressive diseases and injury within the eye. This study demonstrates the application of steerable convolution filters capable of automatically separating gradient orientations to identify edges and delineate tissue boundaries. The edge maps were recombined to measure thickness of individual retinal layers. This technique was successfully applied to longitudinally monitor changes in retinal morphology in a mouse model of laser-induced choroidal neovascularization (CNV) and human data from age-related macular degeneration patients. The steerable filters allow for direct segmentation of noisy images, while novel recombination of weaker segmentations allow for denoising post-segmentation. The segmentation before denoising strategy allows the rapid detection of thin retinal layers even under suboptimal imaging conditions.

  3. Computer-aided retinal photocoagulation system

    NASA Astrophysics Data System (ADS)

    Barrett, Steven F.; Wright, Cameron H.; Jerath, Maya R.; Lewis, R. Stephen; Dillard, Bryan C.; Rylander, Henry G.; Welch, Ashley J.

    1996-01-01

    Researchers at the University of Texas at Austin's Biomedical Engineering Laser Laboratory and the U.S. Air Force Academy's Department of Electrical Engineering are developing a computer-assisted prototype retinal photocoagulation system. The project goal is to rapidly and precisely automatically place laser lesions in the retina for the treatment of disorders such as diabetic retinopathy and retinal tears while dynamically controlling the extent of the lesion. Separate prototype subsystems have been developed to control lesion parameters (diameter or depth) using lesion reflectance feedback and lesion placement using retinal vessels as tracking landmarks. Successful subsystem testing results in vivo on pigmented rabbits using an argon continuous wave laser are presented. A prototype integrated system design to simultaneously control lesion parameters and placement at clinically significant speeds is provided.

  4. Primary Vitreoretinal Lymphoma Masquerading as Refractory Retinitis

    PubMed Central

    Zloto, Ofira; Elkader, Amir E. Abd; Fabian, Ido Didi; Vishnevskia-Dai, Vicktoria

    2015-01-01

    Purpose To report a case of a patient with primary vitreoretinal lymphoma masquerading as retinitis. Methods Retrospective review of the patient's clinical, histopathological and imaging records. Results Cytopathology was negative for malignancy, and preliminary polymerase chain reaction results supported the diagnosis of varicella zoster virus retinitis. Therefore, the patient was treated with antiviral therapy. However, under this treatment, the retinitis progressed. As a result, primary vitreoretinal lymphoma was suspected, and empirical treatment with intravitreal methotrexate injections was started. Under this treatment, the ocular features improved. Five months after initial ocular presentation and ocular resolution, the patient presented with central nervous system lymphoma. Conclusion This case should raise the awareness of the variable clinical presentations, the challenging diagnosis and treatment of primary vitreoretinal lymphoma. All cases should be continuously systemically evaluated. PMID:26557084

  5. Autophagy in light-induced retinal damage.

    PubMed

    Chen, Yu; Perusek, Lindsay; Maeda, Akiko

    2016-03-01

    Vision is reliant upon converting photon signals to electrical information which is interpreted by the brain and therefore allowing us to receive information about our surroundings. However, when exposed to excessive light, photoreceptors and other types of cells in the retina can undergo light-induced cell death, termed light-induced retinal damage. In this review, we summarize our current knowledge regarding molecular events in the retina after excessive light exposure and mechanisms of light-induced retinal damage. We also introduce works which investigate potential roles of autophagy, an essential cellular mechanism required for maintaining homeostasis under stress conditions, in the illuminated retina and animal models of light-induced retinal damage. PMID:26325327

  6. Shedding New Light on Retinal Protein Photochemistry

    NASA Astrophysics Data System (ADS)

    Wand, Amir; Gdor, Itay; Zhu, Jingyi; Sheves, Mordechai; Ruhman, Sanford

    2013-04-01

    The ultrafast spectroscopic investigation of novel retinal proteins challenges existing notions concerning the course of primary events in these natural photoreceptors. We review two illustrations here. The first demonstrates that changes in the initial retinal configuration can alter the duration of photochemistry by nearly an order of magnitude in Anabaena sensory rhodopsin, making it as rapid as the ballistic photoisomerization in visual pigments. This prompted a reinvestigation of the much studied bacteriorhodopsin, leading to a similar trend as well, contrary to earlier reports. The second involves the study of xanthorhodopsin, an archaeal proton pump that includes an attached light-harvesting carotenoid. Pump-probe experiments demonstrate the efficient transfer of energy from carotenoid to retinal, providing a first glimpse at a cooperative multichromophore function, which is probably characteristic of many other proteins as well. Finally, we discuss measures required to advance our knowledge from kinetics to mode-specific dynamics concerning this expanding family of biological photoreceptors.

  7. Molecular biology of retinal ganglion cells.

    PubMed Central

    Xiang, M; Zhou, H; Nathans, J

    1996-01-01

    Retinal ganglion cells are the output neurons that encode and transmit information from the eye to the brain. Their diverse physiologic and anatomic properties have been intensively studied and appear to account well for a number of psychophysical phenomena such as lateral inhibition and chromatic opponency. In this paper, we summarize our current view of retinal ganglion cell properties and pose a number of questions regarding underlying molecular mechanisms. As an example of one approach to understanding molecular mechanisms, we describe recent work on several POU domain transcription factors that are expressed in subsets of retinal ganglion cells and that appear to be involved in ganglion cell development. Images Fig. 1 Fig. 2 Fig. 4 Fig. 5 Fig. 6 PMID:8570601

  8. Retinoschisis transposition following a retinal detachment repair

    PubMed Central

    McVeigh, Katherine; Keller, Johannes; Haynes, Richard J.

    2015-01-01

    Objective: The authors have observed this phenomenon of translocation of the schisis cavity in a few previous cases and aim to report this unusual finding. Method: A patient with known superotemporal retinoschisis developed a distinctly separate inferotemporal retinal detachment in his left eye. This was repaired with a vitrectomy, cryotherapy and C2F6 tamponade under local anaesthetic. Following surgery, the retinoschisis was found in the inferonasal quadrant of the eye and remained stable as the gas dispersed. Result: We hypothesise that the tamponading agent compressed the viscous fluid within the area of schisis, displacing the area of schisis circumferentially. Conclusion: This case emphasises that as long as the retinal breaks are properly sealed, no intervention is required with the schisis during rhegmatogenous retinal detachment surgery.

  9. [Muscular Dystrophies Involving the Retinal Function].

    PubMed

    Jägle, H

    2016-03-01

    Muscular dystrophies are rare disorders, with an incidence of approx. 20 in 100 000. Some dystrophies also affect retinal or optic nerve function. In such cases, the ophthalmological findings may be critical for differential diagnosis or patient counseling. For example in Duchenne muscular dystrophy, where the alteration in retinal function seems to reflect cerebral involvement. Other important forms are mitochondrial and metabolic disorders, such as the Kearns-Sayre syndrome and the Refsum syndrome. Molecular genetic analysis has become a major tool for differential diagnosis, but may be complex and demanding. This article gives an overview of major muscular dystrophies involving retinal function and their genetic origin, in order to guide differential diagnosis. PMID:27011029

  10. Prospects for retinal gene replacement therapy.

    PubMed

    Smith, Alexander J; Bainbridge, James W; Ali, Robin R

    2009-04-01

    Inherited retinal degeneration, which includes conditions such as retinitis pigmentosa and Leber congenital amaurosis (LCA), affects approximately 1/3000 of the population in the Western world. It is characterized by loss of vision and results from mutations in any one of >100 different genes. There are currently no effective treatments, but many of the genes have now been identified and their functions elucidated, providing a major impetus to develop gene-based treatments. Preliminary results from three clinical trials indicate that the treatment of a form of LCA by gene therapy can be safe and effective. Here, we discuss the potential for treating other forms of retinal degeneration by gene therapy, focusing on the gene defects that are likely to be the most amenable to treatment. PMID:19303164

  11. Dystroglycan is required for proper retinal layering.

    PubMed

    Lunardi, Andrea; Cremisi, Federico; Dente, Luciana

    2006-02-15

    Dystroglycan (DG) is a transmembrane receptor linking the extracellular matrix to the internal cytoskeleton. Its structural function has been mainly characterized in muscle fibers, but DG plays signaling and developmental roles also in different tissues and cell types. We have investigated the effects of dystroglycan depletion during eye development of Xenopus laevis. We have injected a specific morpholino (Mo) antisense oligonucleotide in the animal pole of one dorsal blastomere of embryos at four cells stage. Mo-mediated loss of DG function caused disruption of the basal lamina layers, increased apoptosis and reduction of the expression domains of specific retinal markers, at early stages. Later in development, morphants displayed unilateral ocular malformations, such as microphtalmia and retinal delayering with photoreceptors and ganglion cells scattered throughout the retina or aggregated in rosette-like structures. These results recall the phenotypes observed in specific human diseases and suggest that DG presence is crucial at early stages for the organization of retinal architecture. PMID:16406325

  12. Integrated computer-aided retinal photocoagulation system

    NASA Astrophysics Data System (ADS)

    Barrett, Steven F.; Wright, Cameron H. G.; Oberg, Erik D.; Rockwell, Benjamin A.; Cain, Clarence P.; Jerath, Maya R.; Rylander, Henry G., III; Welch, Ashley J.

    1996-05-01

    Successful retinal tracking subsystem testing results in vivo on rhesus monkeys using an argon continuous wave laser and an ultra-short pulse laser are presented. Progress on developing an integrated robotic retinal laser surgery system is also presented. Several interesting areas of study have developed: (1) 'doughnut' shaped lesions that occur under certain combinations of laser power, spot size, and irradiation time complicating measurements of central lesion reflectance, (2) the optimal retinal field of view to achieve simultaneous tracking and lesion parameter control, and (3) a fully digital versus a hybrid analog/digital tracker using confocal reflectometry integrated system implementation. These areas are investigated in detail in this paper. The hybrid system warrants a separate presentation and appears in another paper at this conference.

  13. 46 CFR 34.10-5 - Fire pumps-T/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Fire pumps-T/ALL. 34.10-5 Section 34.10-5 Shipping COAST... § 34.10-5 Fire pumps—T/ALL. (a) Tankships shall be equipped with independently driven fire pumps in accordance with table 34.10-5(a). Table 34.10-5(a)—Fire Pumps Size vessel,L.O.A. (feet) Over— Not...

  14. High Accuracy Decoding of Dynamical Motion from a Large Retinal Population.

    PubMed

    Marre, Olivier; Botella-Soler, Vicente; Simmons, Kristina D; Mora, Thierry; Tkačik, Gašper; Berry, Michael J

    2015-07-01

    Motion tracking is a challenge the visual system has to solve by reading out the retinal population. It is still unclear how the information from different neurons can be combined together to estimate the position of an object. Here we recorded a large population of ganglion cells in a dense patch of salamander and guinea pig retinas while displaying a bar moving diffusively. We show that the bar's position can be reconstructed from retinal activity with a precision in the hyperacuity regime using a linear decoder acting on 100+ cells. We then took advantage of this unprecedented precision to explore the spatial structure of the retina's population code. The classical view would have suggested that the firing rates of the cells form a moving hill of activity tracking the bar's position. Instead, we found that most ganglion cells in the salamander fired sparsely and idiosyncratically, so that their neural image did not track the bar. Furthermore, ganglion cell activity spanned an area much larger than predicted by their receptive fields, with cells coding for motion far in their surround. As a result, population redundancy was high, and we could find multiple, disjoint subsets of neurons that encoded the trajectory with high precision. This organization allows for diverse collections of ganglion cells to represent high-accuracy motion information in a form easily read out by downstream neural circuits. PMID:26132103

  15. High Accuracy Decoding of Dynamical Motion from a Large Retinal Population

    PubMed Central

    Marre, Olivier; Botella-Soler, Vicente; Simmons, Kristina D.; Mora, Thierry; Tkačik, Gašper; Berry, Michael J.

    2015-01-01

    Motion tracking is a challenge the visual system has to solve by reading out the retinal population. It is still unclear how the information from different neurons can be combined together to estimate the position of an object. Here we recorded a large population of ganglion cells in a dense patch of salamander and guinea pig retinas while displaying a bar moving diffusively. We show that the bar’s position can be reconstructed from retinal activity with a precision in the hyperacuity regime using a linear decoder acting on 100+ cells. We then took advantage of this unprecedented precision to explore the spatial structure of the retina’s population code. The classical view would have suggested that the firing rates of the cells form a moving hill of activity tracking the bar’s position. Instead, we found that most ganglion cells in the salamander fired sparsely and idiosyncratically, so that their neural image did not track the bar. Furthermore, ganglion cell activity spanned an area much larger than predicted by their receptive fields, with cells coding for motion far in their surround. As a result, population redundancy was high, and we could find multiple, disjoint subsets of neurons that encoded the trajectory with high precision. This organization allows for diverse collections of ganglion cells to represent high-accuracy motion information in a form easily read out by downstream neural circuits. PMID:26132103

  16. Multisensor Fire Observations

    NASA Technical Reports Server (NTRS)

    Boquist, C.

    2004-01-01

    This DVD includes animations of multisensor fire observations from the following satellite sources: Landsat, GOES, TOMS, Terra, QuikSCAT, and TRMM. Some of the animations are included in multiple versions of a short video presentation on the DVD which focuses on the Hayman, Rodeo-Chediski, and Biscuit fires during the 2002 North American fire season. In one version of the presentation, MODIS, TRMM, GOES, and QuikSCAT data are incorporated into the animations of these wildfires. These data products provided rain, wind, cloud, and aerosol data on the fires, and monitored the smoke and destruction created by them. Another presentation on the DVD consists of a panel discussion, in which experts from academia, NASA, and the U.S. Forest Service answer questions on the role of NASA in fighting forest fires, the role of the Terra satellite and its instruments, including the Moderate Resolution Imaging Spectroradiometer (MODIS), in fire fighting decision making, and the role of fire in the Earth's climate. The third section of the DVD features several animations of fires over the years 2001-2003, including animations of global and North American fires, and specific fires from 2003 in California, Washington, Montana, and Arizona.

  17. Libby South Fire, Washington

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On July 9, 2001, a fire burned about 15 miles south of Twisp, Washington, that officials believe was caused by human error. NASA's Moderate-resolution Imaging Spectroradiometer on the Terra satellite observed the fire, indicated with a red dot in this image, on July 10, after the fire had already consumed about 1,240 acres. On July 10, another fire-called the Thirty Mile Fire-trapped 21 firefighters and 2 civilians in a narrow canyon in the Chewuch River Valley, north of Winthrop, WA. (That fire did not erupt until later in the day after this image was acquired and is therefore not visible.) Tragically, four firefighters were killed and six people were injured, including the two civilians. Rolling debris, rugged and steep terrain, and limited access are impeding efforts to contain the now 8,200-acre fire, which according to current fire incident reports, is completely uncontained. Nearly all the areas in the full-size image, including Washington (center), Idaho (right), Oregon (bottom) are in a state of severe drought, which means the region could be in for another devastating fire season. Another fire is visible in Idaho in the full-size image just east of where Idaho borders with Washington and Oregon. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team

  18. Retinal Oximetry in a Healthy Japanese Population

    PubMed Central

    Nakano, Yuki; Shimazaki, Takeru; Kobayashi, Nobuko; Miyoshi, Yukiko; Ono, Aoi; Kobayashi, Mamoru; Shiragami, Chieko; Hirooka, Kazuyuki; Tsujikawa, Akitaka

    2016-01-01

    Purpose To establish the normative database of retinal oximetry using Oxymap T1 in a healthy Japanese population, and study the reproducibility of the measurements in Japanese. Methods We measured oxygen saturation in the major retinal vessels with Oxymap T1 in 252 eyes of 252 healthy Japanese subjects. Fundus images acquired using Oxymap T1 were processed using built-in Oxymap Analyzer software. Reproducibility of retinal oximetry was investigated using 20 eyes of 20 healthy subjects. Results The mean retinal oxygen saturation of 4 quadrants in healthy Japanese was 97.0 ± 6.9% in arteries and 52.8 ± 8.3% in veins. The mean arteriovenous difference in oxygen saturation was 44.2 ± 9.2%. Both arterial and venous oxygen saturation were significantly lower in the temporal side of the retina, especially in the temporal-inferior vessels. However, the arteriovenous difference in oxygen saturation was limited in the 4 quadrants. Interphotograph, intervisit, and interevaluator intraclass correlation coefficients were 0.936–0.979, 0.809–0.837, and 0.732–0.947, respectively. In the major retinal arteries, oxygen saturation increased with age (r = 0.18, p<0.01), at a rate of 0.67% per 10 years. However, venous oxygen saturation showed no correlation with age. Conclusions This study provides the normative database for the Japanese population. The arterial saturation value appears to be higher than other previous studies. Mean retinal oximetry in 4 quadrants with Oxymap T1 has high reproducibility. PMID:27434373

  19. Protease nexin-1 regulates retinal vascular development.

    PubMed

    Selbonne, Sonia; Francois, Deborah; Raoul, William; Boulaftali, Yacine; Sennlaub, Florian; Jandrot-Perrus, Martine; Bouton, Marie-Christine; Arocas, Véronique

    2015-10-01

    We recently identified protease nexin-1 (PN-1) or serpinE2, as a possibly underestimated player in maintaining angiogenic balance. Here, we used the well-characterized postnatal vascular development of newborn mouse retina to further investigate the role and the mechanism of action of PN-1 in physiological angiogenesis. The development of retinal vasculature was analysed by endothelial cell staining with isolectin B4. PN-1-deficient (PN-1(-/-)) retina displayed increased vascularization in the postnatal period, with elevated capillary thickness and density, compared to their wild-type littermate (WT). Moreover, PN-1(-/-) retina presented more veins/arteries than WT retina. The kinetics of retinal vasculature development, retinal VEGF expression and overall retinal structure were similar in WT and PN-1(-/-) mice, but we observed a hyperproliferation of vascular cells in PN-1(-/-) retina. Expression of PN-1 was analysed by immunoblotting and X-Gal staining of retinas from mice expressing beta-galactosidase under a PN-1 promoter. PN-1 was highly expressed in the first week following birth and then progressively decreased to a low level in adult retina where it localized on the retinal arteries. PCR arrays performed on mouse retinal RNA identified two angiogenesis-related factors, midkine and Smad5, that were overexpressed in PN-1(-/-) newborn mice and this was confirmed by RT-PCR. Both the higher vascularization and the overexpression of midkine and Smad5 mRNA were also observed in gastrocnemius muscle of PN-1(-/-) mice, suggesting that PN-1 interferes with these pathways. Together, our results demonstrate that PN-1 strongly limits physiological angiogenesis and suggest that modulation of PN-1 expression could represent a new way to regulate angiogenesis. PMID:26109427

  20. Reading Visual Braille with a Retinal Prosthesis

    PubMed Central

    Lauritzen, Thomas Z.; Harris, Jordan; Mohand-Said, Saddek; Sahel, Jose A.; Dorn, Jessy D.; McClure, Kelly; Greenberg, Robert J.

    2012-01-01

    Retinal prostheses, which restore partial vision to patients blinded by outer retinal degeneration, are currently in clinical trial. The Argus II retinal prosthesis system was recently awarded CE approval for commercial use in Europe. While retinal prosthesis users have achieved remarkable visual improvement to the point of reading letters and short sentences, the reading process is still fairly cumbersome. This study investigates the possibility of using an epiretinal prosthesis to stimulate visual braille as a sensory substitution for reading written letters and words. The Argus II retinal prosthesis system, used in this study, includes a 10 × 6 electrode array implanted epiretinally, a tiny video camera mounted on a pair of glasses, and a wearable computer that processes the video and determines the stimulation current of each electrode in real time. In the braille reading system, individual letters are created by a subset of dots from a 3 by 2 array of six dots. For the visual braille experiment, a grid of six electrodes was chosen out of the 10 × 6 Argus II array. Groups of these electrodes were then directly stimulated (bypassing the camera) to create visual percepts of individual braille letters. Experiments were performed in a single subject. Single letters were stimulated in an alternative forced choice (AFC) paradigm, and short 2–4-letter words were stimulated (one letter at a time) in an open-choice reading paradigm. The subject correctly identified 89% of single letters, 80% of 2-letter, 60% of 3-letter, and 70% of 4-letter words. This work suggests that text can successfully be stimulated and read as visual braille in retinal prosthesis patients. PMID:23189036

  1. Preservation of retinotopic map in retinal degeneration.

    PubMed

    Xie, John; Wang, Gene-Jack; Yow, Lindy; Humayun, Mark S; Weiland, James D; Cela, Carlos J; Jadvar, Hossein; Lazzi, Gianluca; Dhrami-Gavazi, Elona; Tsang, Stephen H

    2012-05-01

    Retinal degenerations trigger the loss of photoreceptors and cause the remaining de-afferented neural retina to undergo remodeling. Concerns over this potential retinal synaptic reorganization following visual loss have raised questions regarding the usefulness of visual restoration via retinal electrical stimulation. We have used quantitative positron emission tomography (PET) and 2-deoxy-2-[18F]fluoro-d-glucose (FDG) to objectively evaluate the connection between the retina and the primary visual cortex under both light and transcorneal electrical stimulation (TcES) in five subjects with retinal degeneration (RD) who have had more than ten years of light-perception-only best visual acuity and five age-matched normal-sighted controls. All subjects underwent quantitative PET with FDG as the metabolic tracer during stimulation of the right eye under both light stimulation condition and transcorneal electrical stimulation (TcES) using ERG-Jet contact lens electrode. Cortical activation maps from each stimulation condition were obtained using statistical parametric mapping. TcES phosphene threshold current and qualitative visual cortex activation from both stimulation conditions were compared between the two subject groups. Average phosphene threshold current was 0.72 ± 0.18 mA for the five normal-sighted controls and 3.08 ± 2.01 mA for the retinal degenerative subjects. Phosphene threshold current was significantly higher in retinal degenerative subjects compared to normal-sighted controls (p < 0.05). We found both light stimulation and TcES resulted in retinotopically mapped primary visual cortex activation in both groups. In addition, the patterns of early visual area activation between the two subject groups are more similar during TcES than light stimulation. Our findings suggest primary visual cortex continues to maintain its retinotopy in RD subjects despite prolonged visual loss. PMID:22685713

  2. Metamorphopsia Associated with Branch Retinal Vein Occlusion

    PubMed Central

    Manabe, Koichiro; Tsujikawa, Akitaka; Osaka, Rie; Nakano, Yuki; Fujita, Tomoyoshi; Shiragami, Chieko; Hirooka, Kazuyuki; Uji, Akihito; Muraoka, Yuki

    2016-01-01

    Purpose To apply M-CHARTS for quantitative measurements of metamorphopsia in eyes with acute branch retinal vein occlusion (BRVO) and to elucidate the pathomorphology that causes metamorphopsia. Methods This prospective study consisted of 42 consecutive patients (42 eyes) with acute BRVO. Both at baseline and one month after treatment with ranibizumab, metamorphopsia was measured with M-CHARTS, and the retinal morphological changes were examined with optical coherence tomography. Results At baseline, metamorphopsia was detected in the vertical and/or horizontal directions in 29 (69.0%) eyes; the mean vertical and horizontal scores were 0.59 ± 0.57 and 0.52 ± 0.67, respectively. The maximum inner retinal thickness showed no association with the M-CHARTS score, but the M-CHARTS score was correlated with the total foveal thickness (r = 0.43, p = 0.004), the height of serous retinal detachment (r = 0.31, p = 0.047), and the maximum outer retinal thickness (r = 0.36, p = 0.020). One month after treatment, both the inner and outer retinal thickness substantially decreased. However, metamorphopsia persisted in 26 (89.7%) of 29 eyes. The posttreatment M-CHARTS score was not correlated with any posttreatment morphological parameters. However, the posttreatment M-CHARTS score was weakly correlated with the baseline total foveal thickness (r = 0.35. p = 0.024) and closely correlated with the baseline M-CHARTS score (r = 0.78, p < 0.001). Conclusions Metamorphopsia associated with acute BRVO was quantified using M-CHARTS. Initial microstructural changes in the outer retina from acute BRVO may primarily account for the metamorphopsia. PMID:27123642

  3. Fires in Southern Georgia

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Several large fires were burning in southern Georgia on April 29, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite passed overhead and captured this image. Places where MODIS detected actively burning fires are outlined in red. The Roundabout Fire sprang up on April 27, according to the U.S. Southern Area Coordination Center, and was about 3,500 acres as of April 30. That fire was threatening homes in the community of Kirkland. Meanwhile, south of Waycross, two large blazes were burning next to each other in the northern part of Okefenokee Swamp. The Sweat Farm Road Fire threatened the town of Waycross in previous weeks, but at the end of April, activity had moved to the southeastern perimeter. The fire had affected more than 50,000 acres of timber (including pine tree plantations) and swamps. Scores of residences scattered throughout the rural area are threatened. The Big Turnaround Complex is burning to the east. The 26,000-acre fire was extremely active over the weekend, with flame lengths more than 60 feet (just over 18 meters) in places. The two blazes appeared to overlap in fire perimeter maps available from the U.S. Geospatial Multi-Agency Coordination Team. According to the Southern Area Coordination Center morning report on April 30, the Sweat Farm Road Fire 'will be a long term fire. Containment and control will depend on significant rainfall, due to the inaccessible swamp terrain.' No expected containment date was available for the Big Turnaround Complex Fire, either. Describing that fire, the report stated, 'Heavy fuel loading, high fire danger, and difficulty of access continue to hamper suppression efforts.' The large image provided above has a spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response Team provides twice-daily images of the region in additional resolutions. They also provide a version of the image that shows smoke plumes stretching out across the Atlantic Ocean.

  4. ON and OFF retinal ganglion cells differentially regulate serotonergic and GABAergic activity in the dorsal raphe nucleus.

    PubMed

    Zhang, Ting; Huang, Lu; Zhang, Li; Tan, Minjie; Pu, Mingliang; Pickard, Gary E; So, Kwok-Fai; Ren, Chaoran

    2016-01-01

    The dorsal raphe nucleus (DRN), the major source of serotonergic input to the forebrain, receives excitatory input from the retina that can modulate serotonin levels and depressive-like behavior. In the Mongolian gerbil, retinal ganglion cells (RGCs) with alpha-like morphological and Y-like physiological properties innervate the DRN with ON DRN-projecting RGCs out numbering OFF DRN-projecting RGCs. The DRN neurons targeted by ON and OFF RGCs are unknown. To explore retino-raphe anatomical organization, retinal afferents labeled with Cholera toxin B were examined for association with the postsynaptic protein PSD-95. Synaptic associations between retinal afferents and DRN serotonergic and GABAergic neurons were observed. To explore retino-raphe functional organization, light-evoked c-fos expression was examined. Light significantly increased the number of DRN serotonergic and GABAergic cells expressing c-Fos. When ON RGCs were rendered silent while enhancing the firing rate of OFF RGCs, c-Fos expression was greatly increased in DRN serotonergic neurons suggesting that OFF DRN-projecting RGCs predominately activate serotonergic neurons whereas ON DRN-projecting RGCs mainly target GABAergic neurons. Direct glutamatergic retinal input to DRN 5-HT neurons contributes to the complex excitatory drive regulating these cells. Light, via the retinoraphe pathway can modify DRN 5-HT neuron activity which may play a role in modulating affective behavior. PMID:27181078

  5. ON and OFF retinal ganglion cells differentially regulate serotonergic and GABAergic activity in the dorsal raphe nucleus

    PubMed Central

    Zhang, Ting; Huang, Lu; Zhang, Li; Tan, Minjie; Pu, Mingliang; Pickard, Gary E.; So, Kwok-Fai; Ren, Chaoran

    2016-01-01

    The dorsal raphe nucleus (DRN), the major source of serotonergic input to the forebrain, receives excitatory input from the retina that can modulate serotonin levels and depressive-like behavior. In the Mongolian gerbil, retinal ganglion cells (RGCs) with alpha-like morphological and Y-like physiological properties innervate the DRN with ON DRN-projecting RGCs out numbering OFF DRN-projecting RGCs. The DRN neurons targeted by ON and OFF RGCs are unknown. To explore retino-raphe anatomical organization, retinal afferents labeled with Cholera toxin B were examined for association with the postsynaptic protein PSD-95. Synaptic associations between retinal afferents and DRN serotonergic and GABAergic neurons were observed. To explore retino-raphe functional organization, light-evoked c-fos expression was examined. Light significantly increased the number of DRN serotonergic and GABAergic cells expressing c-Fos. When ON RGCs were rendered silent while enhancing the firing rate of OFF RGCs, c-Fos expression was greatly increased in DRN serotonergic neurons suggesting that OFF DRN-projecting RGCs predominately activate serotonergic neurons whereas ON DRN-projecting RGCs mainly target GABAergic neurons. Direct glutamatergic retinal input to DRN 5-HT neurons contributes to the complex excitatory drive regulating these cells. Light, via the retinoraphe pathway can modify DRN 5-HT neuron activity which may play a role in modulating affective behavior. PMID:27181078

  6. Aquaporin 4-specific T cells and NMO-IgG cause primary retinal damage in experimental NMO/SD.

    PubMed

    Zeka, Bleranda; Hastermann, Maria; Kaufmann, Nathalie; Schanda, Kathrin; Pende, Marko; Misu, Tatsuro; Rommer, Paulus; Fujihara, Kazuo; Nakashima, Ichiro; Dahle, Charlotte; Leutmezer, Fritz; Reindl, Markus; Lassmann, Hans; Bradl, Monika

    2016-01-01

    Neuromyelitis optica/spectrum disorder (NMO/SD) is a severe, inflammatory disease of the central nervous system (CNS). In the majority of patients, it is associated with the presence of pathogenic serum autoantibodies (the so-called NMO-IgGs) directed against the water channel aquaporin 4 (AQP4), and with the formation of large, astrocyte-destructive lesions in spinal cord and optic nerves. A large number of recent studies using optical coherence tomography (OCT) demonstrated that damage to optic nerves in NMO/SD is also associated with retinal injury, as evidenced by retinal nerve fiber layer (RNFL) thinning and microcystic inner nuclear layer abnormalities. These studies concluded that retinal injury in NMO/SD patients results from secondary neurodegeneration triggered by optic neuritis.However, the eye also contains cells expressing AQP4, i.e., Müller cells and astrocytes in the retina, epithelial cells of the ciliary body, and epithelial cells of the iris, which raised the question whether the eye can also be a primary target in NMO/SD. Here, we addressed this point in experimental NMO/SD (ENMO) induced in Lewis rat by transfer of AQP4268-285-specific T cells and NMO-IgG.We show that these animals show retinitis and subsequent dysfunction/damage of retinal axons and neurons, and that this pathology occurs independently of the action of NMO-IgG. We further show that in the retinae of ENMO animals Müller cell side branches lose AQP4 reactivity, while retinal astrocytes and Müller cell processes in the RNFL/ganglionic cell layers are spared. These changes only occur in the presence of both AQP4268-285-specific T cells and NMO-IgG.Cumulatively, our data show that damage to retinal cells can be a primary event in NMO/SD. PMID:27503347

  7. [Retinal vein occlusion: an interdisciplinary approach].

    PubMed

    Hatz, Katja; Martinez, Maria

    2016-01-01

    Retinal vein occlusion provide a common cause of significant visual reduction but also late ocular complications. The medical care of these patients pursue two goals: On the one hand vision threatening complications need to be identified and treated, and on the other hand treatable risk factors are need to be identified and treated. This paper summarizes the common ophthalmological therapeutic approaches as well as recommended medical evaluations carried out by the general practitioner. This supports the interdisciplinary approach in evaluating and treating retinal vein occlusions by ophthalmologists and the general practitioners/specialist in internal medicine. PMID:26982647

  8. Laser speckle analysis of retinal vascular dynamics

    PubMed Central

    Neganova, Anastasiia Y; Postnov, Dmitry D; Jacobsen, Jens Christian B.; Sosnovtseva, Olga

    2016-01-01

    Studies of vascular responses are usually performed on isolated vessels or on single vessels in vivo. This allows for precise measurements of diameter or blood flow. However, dynamical responses of the whole microvascular network are difficult to access experimentally. We suggest to use full-field laser speckle imaging to evaluate vascular responses of the retinal network. Image segmentation and vessel recognition algorithms together with response mapping allow us to analyze diameter changes and blood flow responses in the intact retinal network upon systemic administration of the vasoconstrictor angiotensin II, the vasodilator acetylcholine or on the changing level of anesthesia in in vivo rat preparations.

  9. 30 CFR 75.1107-13 - Approval of other fire suppression devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... unattended equipment the fire suppression device shall operate independently of the power to the main motor... independently of the electrical power provided by the cable. (h) On unattended equipment, the sensor system....1107-10. (l) The fire suppression device shall be operable at all times electrical power is...

  10. 30 CFR 75.1107-13 - Approval of other fire suppression devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... unattended equipment the fire suppression device shall operate independently of the power to the main motor... independently of the electrical power provided by the cable. (h) On unattended equipment, the sensor system....1107-10. (l) The fire suppression device shall be operable at all times electrical power is...

  11. Retina derived relaxation is mediated by K(ir) channels and the inhibition of Ca(2+) sensitization in isolated bovine retinal arteries.

    PubMed

    Takır, Selçuk; Uydeş-Doğan, B Sönmez; Özdemir, Osman

    2015-03-01

    Retinal relaxing factor (RRF) has recently been identified as a novel paracrine regulator of retinal circulation acting differently from well known mediators of the endothelium and the retina. Herein, we aimed to characterize the relaxing mechanism of the retina, i.e. RRF, by evaluating the role of Ca(+2)-dependent and -independent signaling mechanisms as well as inward rectifier K(+) (Kir) channels. Retinal relaxation was determined by placing a piece of retinal tissue just on top of the precontracted bovine retinal arteries mounted in a wire myograph. The retina produced a complete relaxation response, which display a biphasic character, in depolarized arteries contracted by L-type Ca(2+) channel agonist, Bay k 8644. Blockade of L-type Ca(2+) channel by nifedipine, inhibition of sarcoplasmic reticulum Ca(2+)-ATPase by cyclopiazonic acid or removal of extracellular Ca(2+) did not influence the prominent relaxation to the retina. Originally, retinal relaxation was found to be unaffected from the inhibition of myosin light chain kinase by ML7, whereas, completely abolished in the presence of myosin light chain phosphatase (MLCP) inhibitor, Calyculin A. Moreover, the inhibition of Rho kinase by its putative inhibitor, Y-27632 displayed comparable relaxant effects to RRF in retinal arteries precontracted either by prostaglandin F2α or K(+), and augmented the moderate response to the retina in K(+) precontracted arteries. In addition, retinal relaxation was significantly inhibited and lost its biphasic character in the presence of Kir channel blocker, Ba(2+). Our results suggested that inhibition of Ca(2+) sensitization through the activation of MLCP, possibly via interfering with Rho kinase, and the opening of Kir channels are likely to be involved in the inhibitory influence of RRF on the retinal arteries. PMID:25662314

  12. CaV3.2 KO mice have altered retinal waves but normal direction selectivity.

    PubMed

    Hamby, Aaron M; Rosa, Juliana M; Hsu, Ching-Hsiu; Feller, Marla B

    2015-01-01

    Early in development, before the onset of vision, the retina establishes direction-selective responses. During this time period, the retina spontaneously generates bursts of action potentials that propagate across its extent. The precise spatial and temporal properties of these "retinal waves" have been implicated in the formation of retinal projections to the brain. However, their role in the development of direction selective circuits within the retina has not yet been determined. We addressed this issue by combining multielectrode array and cell-attached recordings to examine mice that lack the CaV3.2 subunit of T-type Ca2+ channels (CaV3.2 KO) because these mice exhibit disrupted waves during the period that direction selective circuits are established. We found that the spontaneous activity of these mice displays wave-associated bursts of action potentials that are altered from that of control mice: the frequency of these bursts is significantly decreased and the firing rate within each burst is reduced. Moreover, the projection patterns of the retina demonstrate decreased eye-specific segregation in the dorsal lateral geniculate nucleus (dLGN). However, after eye-opening, the direction selective responses of CaV3.2 KO direction selective ganglion cells (DSGCs) are indistinguishable from those of wild-type DSGCs. Our data indicate that although the temporal properties of the action potential bursts associated with retinal waves are important for activity-dependent refining of retinal projections to central targets, they are not critical for establishing direction selectivity in the retina. PMID:25873107

  13. Review: R28 retinal precursor cells: The first 20 years

    PubMed Central

    2014-01-01

    The R28 retinal precursor cell line was established 20 years ago, originating from a postnatal day 6 rat retinal culture immortalized with the 12S E1A (NP-040507) gene of the adenovirus in a replication-incompetent viral vector. Since that time, R28 cells have been characterized and used for a variety of in vitro and in vivo studies of retinal cell behavior, including differentiation, neuroprotection, cytotoxicity, and light stimulation, as well as retinal gene expression and neuronal function. While no cell culture is equivalent to the intact eye, R28 cells continue to provide an important experimental system for the study of many retinal processes. PMID:24644404

  14. Retinal arterial occlusive disease in systemic lupus erythematosus.

    PubMed

    Gold, D; Feiner, L; Henkind, P

    1977-09-01

    Four patients with systemic lupus erythematosus (SLE) developed an unusual form of occlusive retinal arterial disease. The most prominent clinical features of this disorder were deposition of yellow-white material in retinal arterial walls and evidence of multifocal retinal arterial occlusion. Fluorescein angiographic findings included nonperfusion of the obstructed arteries and the retinal capillary beds fed by them, and fluorescein leakage at the sites of involvement of the retinal arteries. This ocular complication of SLE is presumably a manifestation of the widespread systemic vascular problems seen in this disorder. It may be more common in patients with lupus involving the CNS. PMID:901267

  15. Chronic Myeloid Leukaemia Presenting as Bilateral Retinal Haemorrhages with Multiple Retinal Infiltrates

    PubMed Central

    Barot, Rakesh K.; Gohel, Devadatta Jayantilal; Bhagat, Nupur

    2016-01-01

    Chronic Myeloid Leukaemia (CML) causes retinopathy manifesting as venous dilation and tortuosity, perivascular sheathing, retinal haemorrhages, microaneurysms, cotton-wool spots and optic nerve infiltration. Retina is the most commonly involved intraocular structure in CML. However, retinal involvement is a rare form of presentation of CML and few cases have been reported. We report a case of CML presenting as unilateral sudden visual loss. Fundus showed multiple white centered retinal haemorrhages in both eyes with unilateral macular oedema. Blood work-up showed raised WBC count, high platelet count and low Haemoglobin. Cytological analysis of bone marrow biopsy confirmed Philadelphia chromosome. After a course of Imatinib, visual acuity improved and haemorrhages resolved with normalization of macular thickness. In our case, patient presented early, leading to early detection producing better visual prognosis. This highlights the importance of detailed hematological work up in patients with retinal involvement to rule out leukaemic retinopathy.

  16. Probing how initial retinal configuration controls photochemical dynamics in retinal proteins

    NASA Astrophysics Data System (ADS)

    Wand, A.; Rozin, R.; Eliash, T.; Friedman, N.; Jung, K. H.; Sheves, M.; Ruhman, S.

    2013-03-01

    The effects of the initial retinal configuration and the active isomerization coordinate on the photochemistry of retinal proteins (RPs) are assessed by comparing photochemical dynamics of two stable retinal ground state configurations (all-trans,15-anti vs. 13-cis,15-syn), within two RPs: Bacteriorhodopsin (BR) and Anabaena Sensory Rhodopsin (ASR). Hyperspectral pump-probe spectroscopy shows that photochemistry starting from 13-cis retinal in both proteins is 3-10 times faster than when started in the all-trans state, suggesting that the hastening is ubiquitous to microbial RPs, regardless of their different biological functions and origin. This may also relate to the known disparity of photochemical rates between microbial RPs and visual pigments. Importance and possible underlying mechanisms are discussed as well.

  17. Fires Scorch Oregon

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In southwestern Oregon, the Florence Fire (north) and the Sour Biscuit Fire (south) continued to burn virtually out of control on July 21, 2002. Numerous evacuation notices have been issued for residents in the area as the fires remain difficult to control due to the steep, rugged terrain of the Klamath Mountains. This image is from the Landsat 5 Thematic Mapper. Credit:Image provided by the USGS EROS Data Center Satellite Systems Branch.

  18. Wildland fire management terminology

    SciTech Connect

    Not Available

    1986-01-01

    Prepared by the FAO Forest Resources Development Branch, this book discusses an ongoing project for developing a multi-lingual glossary of fire terminology. It defines specific terms commonly used in wildland fire management that are not defined in standard desk dictionaries, and includes terminology from neighboring fields of meteorology, aviation and structural fire protection. In addition to the English language entries - which include Spanish, Italian, German and French equivalents - there are also separate Spanish, Italian, German and French word lists.

  19. Fire alarm system improvement

    SciTech Connect

    Hodge, S.G.

    1994-10-01

    This document contains the Fire Alarm System Test Procedure for Building 234-5Z, 200-West Area on the Hanford Reservation, Richland, Washington. This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the modifications to the Fire Protection systems function as required by project criteria. The ATP will test the Fire Alarm Control Panels, Flow Alarm Pressure Switch, Heat Detectors, Smoke Detectors, Flow Switches, Manual Pull Stations, and Gong/Door by Pass Switches.

  20. Retinal Detachment Associated with AIDS-Related Cytomegalovirus Retinitis: Risk Factors in a Resource-Limited Setting

    PubMed Central

    Yen, Michael; Chen, Jenny; Ausayakhun, Somsanguan; Kunavisarut, Paradee; Vichitvejpaisal, Pornpattana; Ausayakhun, Sakarin; Jirawison, Choeng; Shantha, Jessica; Holland, Gary N; Heiden, David; Margolis, Todd P; Keenan, Jeremy D

    2014-01-01

    Purpose To determine risk factors predictive of retinal detachment in patients with cytomegalovirus (CMV) retinitis in a setting with limited access to ophthalmic care. Design Case-control study. Methods Sixty-four patients with CMV retinitis and retinal detachment were identified from the Ocular Infectious Diseases and Retina Clinics at Chiang Mai University. Three control patients with CMV retinitis but no retinal detachment were selected for each case, matched by calendar date. The medical records of each patient were reviewed, with patient-level and eye-level features recorded for the clinic visit used to match cases and controls, and also for the initial clinic visit at which CMV retinitis was diagnosed. Risk factors for retinal detachment were assessed separately for each of these time points using multivariate conditional logistic regression models that included 1 eye from each patient. Results Patients with a retinal detachment were more likely than controls to have low visual acuity (OR, 1.24 per line of worse vision on the logMAR scale; 95%CI, 1.16-1.33) and bilateral disease (OR, 2.12; 95%CI, 0.92-4.90). Features present at the time of the initial diagnosis of CMV retinitis that predicted subsequent retinal detachment included bilateral disease (OR, 2.68; 95%CI, 1.18-6.08) and lesion size (OR, 2.64 per 10% increase in lesion size; 95%CI, 1.41-4.94). Conclusion Bilateral CMV retinitis and larger lesion sizes, each of which is a marker of advanced disease, were associated with subsequent retinal detachment. Earlier detection and treatment may reduce the likelihood that patients with CMV retinitis develop a retinal detachment. PMID:25448999

  1. PKC/MAPK signaling suppression by retinal pericyte conditioned medium prevents retinal endothelial cell proliferation.

    PubMed

    Kondo, Tetsu; Hosoya, Ken-Ichi; Hori, Satoko; Tomi, Masatoshi; Ohtsuki, Sumio; Terasaki, Tetsuya

    2005-05-01

    Little is known about the regulation mechanism of endothelial cell proliferation by retinal pericytes. The purpose of this study was to elucidate the suppression mechanism of retinal capillary endothelial cell growth by soluble factors derived from retinal pericytes. Conditioned medium of retinal pericytes (rPCT1-CM) suppressed ischemia-induced retinal neovascularization. The growth and DNA synthesis of TR-iBRB2 cells, a conditionally immortalized rat retinal capillary endothelial cell line, were suppressed in a concentration-dependent manner by concentrated rPCT1-CM. The number of human cultured endothelial cells was also reduced by rPCT1-CM. These results provide the first evidence that CM from the cultivation of pericytes alone can inhibit retinal neovascularization in vivo and in vitro. Although the growth reduction of TR-iBRB2 cells was only partly reversed by treatment of rPCT1-CM with antibodies to transforming growth factor-beta1, it was completely lost by heat-treatment of rPCT1-CM, suggesting that anti-angiogenic factors are soluble proteins. The levels of expression of G1/S-phase-related proteins, such as cyclin D1, cyclin-dependent kinase (cdk)4, cdk6, and proliferating cell nuclear antigen, were reduced and a cdk inhibitor, p21(Cip1), was induced in rPCT1-CM-treated TR-iBRB2 cells. Moreover, phosphorylated p44/42 mitogen-activated protein kinase (p44/42 MAPK) in TR-iBRB2 cells was reduced by rPCT1-CM treatment and phosphorylated protein kinase C (PKC)alpha/betaII, which is upstream of p44/42 MAPK, was also suppressed. In conclusion, CM from retinal pericytes suppresses PKC-p44/42 MAPK signaling, inhibits endothelial cell growth, and prevents retinal neovascularization. Anti-angiogenic factors derived from retinal pericytes are likely to play a critical role in the regulation of retinal endothelial cell growth. PMID:15499572

  2. Biallelic Mutations in the Autophagy Regulator DRAM2 Cause Retinal Dystrophy with Early Macular Involvement

    PubMed Central

    El-Asrag, Mohammed E.; Sergouniotis, Panagiotis I.; McKibbin, Martin; Plagnol, Vincent; Sheridan, Eamonn; Waseem, Naushin; Abdelhamed, Zakia; McKeefry, Declan; Van Schil, Kristof; Poulter, James A.; Black, Graeme; Hall, Georgina; Ingram, Stuart; Gillespie, Rachel; Ramsden, Simon; Manson, Forbes; Hardcastle, Alison; Michaelides, Michel; Cheetham, Michael; Arno, Gavin; Thomas, Niclas; Bhattacharya, Shomi; Moore, Tony; Nemeth, Andrea; Downes, Susan; Lise, Stefano; Lord, Emma; Johnson, Colin A.; Carr, Ian M.; Leroy, Bart P.; De Baere, Elfride; Inglehearn, Chris F.; Webster, Andrew R.; Toomes, Carmel; Ali, Manir

    2015-01-01

    Retinal dystrophies are an overlapping group of genetically heterogeneous conditions resulting from mutations in more than 250 genes. Here we describe five families affected by an adult-onset retinal dystrophy with early macular involvement and associated central visual loss in the third or fourth decade of life. Affected individuals were found to harbor disease-causing variants in DRAM2 (DNA-damage regulated autophagy modulator protein 2). Homozygosity mapping and exome sequencing in a large, consanguineous British family of Pakistani origin revealed a homozygous frameshift variant (c.140delG [p.Gly47Valfs∗3]) in nine affected family members. Sanger sequencing of DRAM2 in 322 unrelated probands with retinal dystrophy revealed one European subject with compound heterozygous DRAM2 changes (c.494G>A [p.Trp165∗] and c.131G>A [p.Ser44Asn]). Inspection of previously generated exome sequencing data in unsolved retinal dystrophy cases identified a homozygous variant in an individual of Indian origin (c.64_66del [p.Ala22del]). Independently, a gene-based case-control association study was conducted via an exome sequencing dataset of 18 phenotypically similar case subjects and 1,917 control subjects. Using a recessive model and a binomial test for rare, presumed biallelic, variants, we found DRAM2 to be the most statistically enriched gene; one subject was a homozygote (c.362A>T [p.His121Leu]) and another a compound heterozygote (c.79T>C [p.Tyr27His] and c.217_225del [p.Val73_Tyr75del]). DRAM2 encodes a transmembrane lysosomal protein thought to play a role in the initiation of autophagy. Immunohistochemical analysis showed DRAM2 localization to photoreceptor inner segments and to the apical surface of retinal pigment epithelial cells where it might be involved in the process of photoreceptor renewal and recycling to preserve visual function. PMID:25983245

  3. Biallelic mutations in the autophagy regulator DRAM2 cause retinal dystrophy with early macular involvement.

    PubMed

    El-Asrag, Mohammed E; Sergouniotis, Panagiotis I; McKibbin, Martin; Plagnol, Vincent; Sheridan, Eamonn; Waseem, Naushin; Abdelhamed, Zakia; McKeefry, Declan; Van Schil, Kristof; Poulter, James A; Johnson, Colin A; Carr, Ian M; Leroy, Bart P; De Baere, Elfride; Inglehearn, Chris F; Webster, Andrew R; Toomes, Carmel; Ali, Manir

    2015-06-01

    Retinal dystrophies are an overlapping group of genetically heterogeneous conditions resulting from mutations in more than 250 genes. Here we describe five families affected by an adult-onset retinal dystrophy with early macular involvement and associated central visual loss in the third or fourth decade of life. Affected individuals were found to harbor disease-causing variants in DRAM2 (DNA-damage regulated autophagy modulator protein 2). Homozygosity mapping and exome sequencing in a large, consanguineous British family of Pakistani origin revealed a homozygous frameshift variant (c.140delG [p.Gly47Valfs(∗)3]) in nine affected family members. Sanger sequencing of DRAM2 in 322 unrelated probands with retinal dystrophy revealed one European subject with compound heterozygous DRAM2 changes (c.494G>A [p.Trp165(∗)] and c.131G>A [p.Ser44Asn]). Inspection of previously generated exome sequencing data in unsolved retinal dystrophy cases identified a homozygous variant in an individual of Indian origin (c.64_66del [p.Ala22del]). Independently, a gene-based case-control association study was conducted via an exome sequencing dataset of 18 phenotypically similar case subjects and 1,917 control subjects. Using a recessive model and a binomial test for rare, presumed biallelic, variants, we found DRAM2 to be the most statistically enriched gene; one subject was a homozygote (c.362A>T [p.His121Leu]) and another a compound heterozygote (c.79T>C [p.Tyr27His] and c.217_225del [p.Val73_Tyr75del]). DRAM2 encodes a transmembrane lysosomal protein thought to play a role in the initiation of autophagy. Immunohistochemical analysis showed DRAM2 localization to photoreceptor inner segments and to the apical surface of retinal pigment epithelial cells where it might be involved in the process of photoreceptor renewal and recycling to preserve visual function. PMID:25983245

  4. Cavefish eye loss in response to an early block of retinal differentiation progression

    PubMed Central

    Foulkes, Nicholas S.; Bertolucci, Cristiano; Wittbrodt, Joachim

    2015-01-01

    Summary The troglomorphic phenotype shared by diverse cave-dwelling animals is regarded as one of the classical examples of convergent evolution. One unresolved question relates to whether the characteristic eye loss in diverse cave species is based on interference with the same genetic program. Phreatichthys andruzzii, a Somalian cavefish, has evolved under constant conditions in complete darkness and shows severe troglomorphic characteristics such as complete loss of eyes, pigments and scales. In the course of early embryonic development, a complete eye is formed that is subsequently lost. In Astyanax mexicanus, another blind cavefish, eye loss has been attributed to interferences during eye field patterning. To address whether similar pathways have been targeted by evolution independently, we investigated the retinal development of P. andruzzii studying the expression of marker genes involved in eye patterning, morphogenesis, differentiation and maintenance. In contrast to Astyanax, patterning of the eye field and evagination of the optic vesicles proceeds without obvious deviation. However, the subsequent differentiation of retinal cell types is arrested during the generation of the first-born cell type, retinal ganglion cells, which also fail to project correctly to the optic tectum. Eye degeneration in both species is driven by progressive apoptosis. However it is retinal apoptosis in Phreatichthys that progresses in a wave-like manner and eliminates progenitor cells that fail to differentiate in contrast to Astyanax, where lens apoptosis appears to serve as a driving force. Thus, evolution has targeted late retinal differentiation events indicating that there are several ways to discontinue the development and maintenance of an eye. PMID:25617433

  5. Absolute Retinal Blood Flow Measurement With a Dual-Beam Doppler Optical Coherence Tomography

    PubMed Central

    Dai, Cuixia; Liu, Xiaojing; Zhang, Hao F.; Puliafito, Carmen A.; Jiao, Shuliang

    2013-01-01

    Purpose. To test the capability of a novel dual-beam Doppler optical coherence tomography (OCT) technique for simultaneous in vivo measurement of the Doppler angle and, thus, the absolute retinal blood velocity and the retinal flow rate, without the influence of motion artifacts. Methods. A novel dual-beam Doppler spectral domain OCT (SD-OCT) was developed. The two probing beams are separated with a controllable distance along an arbitrary direction, both of which are controlled by two independent 2D optical scanners. Two sets of optical Doppler tomography (ODT) images are acquired simultaneously. The Doppler angle of each blood vessel segment is calculated from the relative coordinates of the centers of the blood vessel in the two corresponding ODT images. The absolute blood flow velocity and the volumetric blood flow rate can then be calculated. To measure the total retinal blood flow, we used a circular scan pattern centered at the optic disc to obtain two sets of concentric OCT/ODT images simultaneously. Results. We imaged two normal human subjects at ages of 48 and 34 years. The total retinal blood flow rates of the two human subjects were calculated to be 47.01 μL/min (older subject) and 51.37 μL/min (younger subject), respectively. Results showed that the performance of this imaging system is immune to eye movement, since the two sets of ODT images were acquired simultaneously. Conclusions. The dual-beam OCT/ODT system is successful in measuring the absolute retinal blood velocity and the volumetric flow rate. The advantage of the technique is that the two sets of ODT images used for the calculation are acquired simultaneously, which eliminates the influence of eye motion and ensures the accuracy of the calculated hemodynamic parameters. PMID:24222303

  6. Association of body composition and blood pressure categories with retinal vessel diameters in primary school children.

    PubMed

    Imhof, Katharina; Zahner, Lukas; Schmidt-Trucksäss, Arno; Hanssen, Henner

    2016-06-01

    Alterations in retinal vessel diameters have been shown to be predictive of cardiovascular risk in adults and children. The aim of our study was to examine the association of body composition and blood pressure (BP) categories with retinal vessel diameters in school children. We examined anthropometric parameters, BP and retinal arteriolar (CRAE) and venular (CRVE) diameters as well as the arteriolar-to-venular diameter ratio (AVR) in 391 children (age: 7.3, s.d. 0.4). Differences between the lowest and highest BP quartiles indicated that higher systolic and diastolic BP were associated with narrower CRAE (P<0.001 for both). Children in the highest weight quartile had narrower CRAE compared with the lowest quartile (P=0.05). In the regression analysis, systolic and diastolic BP were associated with arteriolar narrowing (-0.4 measuring units (mu) per mm Hg, 95% confidence interval: [-0.6; -0.3] and -0.6 mu per mm Hg [-0.7; -0.4], respectively; P<0.001 for both). An independent association was found for diastolic BP only. Compared with normotensives (NT; 74.4% of cohort), arteriolar narrowing was already seen in children categorized as pre-hypertensive (PHT) (11.5% of cohort), which was similar to HT children (14.1% of cohort) (NT: mean 207.2 [205.6; 208.7] mu; PHT: 201.7 [197.8; 205.7] mu; HT: 199.7 [196.2; 203.3] mu; P=0.01 for PHT vs. NT and P<0.001 for HT vs. NT in systolic BP). Our results suggest that systolic and diastolic BP are main determinants of retinal arteriolar diameters; and therefore, microvascular health in young children. Pre-hypertension seems to be associated with retinal microvascular alterations early in life. PMID:26763853

  7. Peripheral Retinal Vascular Patterns in Patients with Rhegmatogenous Retinal Detachment in Taiwan

    PubMed Central

    Chen, San-Ni; Hwang, Jiunn-Feng; Wu, Wen-Chuan

    2016-01-01

    This is an observational study of fluorescein angiography (FA) in consecutive patients with rhegmatogenous retinal detachment (RRD) in Changhua Christian Hospital to investigate the peripheral retinal vascular patterns in those patients. All patients had their age, sex, axial length (AXL), and refraction status (RF) recorded. According to the findings in FA of the peripheral retina, the eyes were divided into 4 groups: in group 1, there was a ramified pattern of peripheral retinal vasculature with gradual tapering; in group 2, there was an abrupt ending of peripheral vasculature with peripheral non-perfusion; in group 3, there was a curving route of peripheral vasculature forming vascular arcades or anastomosis; and in group 4, the same as in group 3, but with one or more wedge-shaped avascular notches. Comparisons of age, sex, AXL, and RF, association of breaks with lattice degeneration and retinal non-perfusion, surgical procedures utilized, and mean numbers of operations were made among the four groups. Of the 73 eyes studied, there were 13 eyes (17.8%) in group 1, 3 eyes (4.1%) in group 2, 40 eyes (54.8%) in group 3 and 17 eyes (23.3%) in group 4. Significant differences in age, AXL and RF, and association of retinal breaks to non-perfusion were noted among the four groups. Patients in group 1 had older ages, while younger ages were noted in groups 3 and 4. Eyes in group 1 had the shortest average AXL and were least myopic in contrast to the eyes in groups 3 and 4. Association of retinal breaks and retinal non-perfusion was significantly higher in groups 2, 3 and 4 than in group 1. In conclusion, peripheral vascular anomalies are common in cases with RRD. Patients with peripheral non-perfusion tend to be younger, with longer axial length and have the breaks associated with retinal non-perfusion. PMID:26909812

  8. Retinal arteriolar occlusions due to cytomegalovirus retinitis in elderly patients without HIV

    PubMed Central

    2013-01-01

    Background Five of 7 (71%) elderly immunocompetent patients with cytomegalovirus retinitis had retinal arteriolar occlusions versus 2 of 8 (25%) elderly immunocompromised patients and 1 of 19 (5%) younger HIV-infected patients. Compared to HIV-infected patients, elderly patients were more likely to have occlusive events, neovascularization or hemorrhage, and underlying vasculopathy. The purpose of this study is to report the novel finding of extensive retinal arteriolar occlusions and neovascularization in immunocompetent patients with cytomegalovirus retinitis. This is a retrospective observational cohort study of cytomegalovirus retinitis (CMVR) in a university setting. Seven patients were elderly but not immunocompromised, 8 were elderly and iatrogenically immunocompromised, and 16 were HIV-infected. All patients underwent polymerase chain reaction testing of intraocular fluid. Primary outcome measure was visual acuity. Secondary outcome measures were vascular occlusions, ischemic complications, and response to treatment. Results Mean age was 73, 70, and 41 years for immunocompetent, immunocompromised, and HIV-infected patients, respectively. Diabetes and vascular disease were common in the elderly. Vision loss to less than 5/200 occurred in 50% of the immunocompetent elderly patients, and 17% of CMV eyes in immunocompromised and HIV patients. Occlusion of the entire retinal vasculature occurred in 4/7 (57%) of immunocompetent patients despite lack of Zone I involvement, and rubeosis occurred in three, disc neovascularization in one, and vitreous hemorrhage in two patients. Vascular occlusive events were less common in immunocompromised patients and rare in the HIV-infected. Conclusions CMVR in non-HIV-infected elderly patients is associated with retinal arteriolar occlusions. An intact host immune response may increase damage to retinal vessels. Prompt diagnosis may avert catastrophic vision loss. PMID:23514532

  9. Plasma Kallikrein Mediates Retinal Vascular Dysfunction and Induces Retinal Thickening in Diabetic Rats

    PubMed Central

    Clermont, Allen; Chilcote, Tamie J.; Kita, Takeshi; Liu, Jia; Riva, Priscilla; Sinha, Sukanto; Feener, Edward P.

    2011-01-01

    OBJECTIVE Plasma kallikrein (PK) has been identified in vitreous fluid obtained from individuals with diabetic retinopathy and has been implicated in contributing to retinal vascular dysfunction. In this report, we examined the effects of PK on retinal vascular functions and thickness in diabetic rats. RESEARCH DESIGN AND METHODS We investigated the effects of a selective PK inhibitor, ASP-440, and C1 inhibitor (C1-INH), the primary physiological inhibitor of PK, on retinal vascular permeability (RVP) and hemodynamics in rats with streptozotocin-induced diabetes. The effect of intravitreal PK injection on retinal thickness was examined by spectral domain optical coherence tomography. RESULTS Systemic continuous administration of ASP-440 for 4 weeks initiated at the time of diabetes onset inhibited RVP by 42% (P = 0.013) and 83% (P < 0.001) at doses of 0.25 and 0.6 mg/kg per day, respectively. Administration of ASP-440 initiated 2 weeks after the onset of diabetes ameliorated both RVP and retinal blood flow abnormalities in diabetic rats measured at 4 weeks’ diabetes duration. Intravitreal injection of C1-INH similarly decreased impaired RVP in rats with 2 weeks’ diabetes duration. Intravitreal injection of PK increased both acute RVP and sustained focal RVP (24 h postinjection) to a greater extent in diabetic rats compared with nondiabetic control rats. Intravitreal injection of PK increased retinal thickness compared with baseline to a greater extent (P = 0.017) in diabetic rats (from 193 ± 10 μm to 223 ± 13 μm) compared with nondiabetic rats (from 182 ± 8 μm to 193 ± 9 μm). CONCLUSIONS These results show that PK contributes to retinal vascular dysfunctions in diabetic rats and that the combination of diabetes and intravitreal injection of PK in rats induces retinal thickening. PMID:21444925

  10. Retinal Changes in an ATP-Induced Model of Retinal Degeneration

    PubMed Central

    Aplin, Felix P.; Vessey, Kirstan A.; Luu, Chi D.; Guymer, Robyn H.; Shepherd, Robert K.; Fletcher, Erica L.

    2016-01-01

    In rodents and felines, intravitreal administration of adenosine triphosphate (ATP) has been shown to induce photoreceptor death providing a tractable model of retinal degeneration in these species. This study investigated the long term effects of photoreceptor loss in an ATP induced feline model of retinal degeneration. Six normal sighted felines were unilaterally blinded using intravitreal ATP injections and assessed using electroretinography (ERG) and optical coherence tomography (OCT). At 30 h (n = 3) or 12 weeks (n = 3) post-injection, the animals were euthanized and the eyes enucleated. Retinae were sectioned and labeled using immunohistochemistry for markers of cell death, neural remodeling and gliosis. Ongoing cell death and retinal degeneration was observed in the outer retina at both 30 h and 12 weeks following unilateral ATP injection. Markers of mid to late-stage retinal remodeling such as cell displacement and aberrant neurite growth were observed in the inner retina at 12 weeks post-injection. Ganglion cells appeared to remain intact in ATP injected eyes. Müller cell gliosis was observed throughout the inner and outer retina, in some parts completely enveloping and/or displacing the surviving neural tissue. Our data suggests that the ATP injected feline retina continues to undergo progressive retinal degeneration and exhibits abnormalities consistent with a description of retinal remodeling commonly seen in other models of retinal degeneration. These findings validate the use of intravitreal ATP injection in feline as a large animal model of retinal degeneration which may aid in development of therapies aiming to restore visual function after photoreceptor degeneration. PMID:27199678

  11. Fires Scorch Oregon

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In southwestern Oregon, the Florence Fire (north) and the Sour Biscuit Fire (south) continue to burn virtually out of control. Numerous evacuation notices have been issued for residents in the area as the fires remain difficult to control due to the steep, rugged terrain of the Klamath Mountains. This false-color image from the Landsat 5 Thematic Mapper was acquired on July 21, 2002. In the image, vegetation is green, burned areas are deep magenta, active fire is bright pink, and smoke is light blue. Credit:Image provided by the USGS EROS Data Center Satellite Systems Branch.

  12. Fires Scorch Oregon

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In southwestern Oregon, the Florence Fire (north) and the Sour Biscuit Fire (south) continue to grow explosively. This image from the Landsat 7 Enhanced Thematic Mapper Plus was captured on July 29, 2002. The Florence Fire had grown to 50,000 acres and the Sour Biscuit Fire had grown to 16,000 acres. Numerous evacuation notices remain in effect. In this false-color image, vegetation is green, burned areas are deep magenta, actively burning fronts are bright pink, and smoke is blue. Credit:Image provided by the USGS EROS Data Center Satellite Systems Branch.

  13. Forest Fire Mapping

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Fire Logistics Airborne Mapping Equipment (FLAME) system, mounted in a twin-engine and airplane operated by the U.S. Forest Service (USFS) of the U.S. Department of Agriculture (USDA), is an airborne instrument for detecting and pinpointing forest fires that might escape ground detection. The FLAME equipment rack includes the operator interface, a video monitor, the system's control panel and film output. FLAME's fire detection sensor is an infrared line scanner system that identifies fire boundaries. Sensor's information is correlated with the aircraft's position and altitude at the time the infrared imagery is acquired to fix the fire's location on a map. System can be sent to a fire locale anywhere in the U.S. at the request of a regional forester. USFS felt a need for a more advanced system to deliver timely fire information to fire management personnel in the decade of the 1990s. The Jet Propulsion Laboratory (JPL) conducted a study, jointly sponsored by NASA and USDA, on what advanced technologies might be employed to produce an end-to-end thermal infrared fire detection and mapping system. That led to initiation of the Firefly system, currently in development at JPL and targeted for operational service beginning in 1992. Firefly will employ satellite-reference position fixing and provide performance superior to FLAME.

  14. NASA Fire Protection

    NASA Technical Reports Server (NTRS)

    Clark, Theodore

    2001-01-01

    This viewgraph presentation provides information on fire protection operations and administration at Stennis Space Center (SSC). The presentation also lists innovative practices and recent improvements.

  15. Determination of Survivable Fires

    NASA Technical Reports Server (NTRS)

    Dietrich, D. L.; Niehaus, J. E.; Ruff, G. A.; Urban, D. L.; Takahashi, F.; Easton, J. W.; Abbott, A. A.; Graf, J. C.

    2012-01-01

    At NASA, there exists no standardized design or testing protocol for spacecraft fire suppression systems (either handheld or total flooding designs). An extinguisher's efficacy in safely suppressing any reasonable or conceivable fire is the primary benchmark. That concept, however, leads to the question of what a reasonable or conceivable fire is. While there exists the temptation to over-size' the fire extinguisher, weight and volume considerations on spacecraft will always (justifiably) push for the minimum size extinguisher required. This paper attempts to address the question of extinguisher size by examining how large a fire a crew member could successfully survive and extinguish in the confines of a spacecraft. The hazards to the crew and equipment during an accidental fire include excessive pressure rise resulting in a catastrophic rupture of the vehicle skin, excessive temperatures that burn or incapacitate the crew (due to hyperthermia), carbon dioxide build-up or other accumulation of other combustion products (e.g. carbon monoxide). Estimates of these quantities are determined as a function of fire size and mass of material burned. This then becomes the basis for determining the maximum size of a target fire for future fire extinguisher testing.

  16. Fire protection design criteria

    SciTech Connect

    1997-03-01

    This Standard provides supplemental fire protection guidance applicable to the design and construction of DOE facilities and site features (such as water distribution systems) that are also provided for fire protection. It is intended to be used in conjunction with the applicable building code, national Fire Protection Association Codes and Standards, and any other applicable DOE construction criteria. This Standard, along with other delineated criteria, constitutes the basic criteria for satisfying DOE fire and life safety objectives for the design and construction or renovation of DOE facilities.

  17. Potential for Autoimmune Pathogenesis of Rift Valley Fever Virus Retinitis

    PubMed Central

    Newman-Gerhardt, Shoshana; Muiruri, Samuel; Muchiri, Eric; Peters, Clarence J.; Morrill, John; Lucas, Alexander H.; King, Charles H.; Kazura, James; LaBeaud, Angelle Desiree

    2013-01-01

    Rift Valley Fever (RVF) is a significant threat to human health because it can progress to retinitis, encephalitis, and hemorrhagic fever. The timing of onset of Rift Valley Fever virus (RVFV) retinitis suggests an autoimmune origin. To determine whether RVFV retinitis is associated with increased levels of IgG against retinal tissue, we measured and compared levels of IgG against healthy human eye tissue by immunohistochemical analysis. We found that serum samples from RVFV-exposed Kenyans with retinitis (n = 8) were slightly more likely to have antibodies against retinal tissue than control populations, but the correlation was not statistically significant. Further investigation into the possible immune pathogenesis of RVFV retinitis could lead to improved therapies to prevent or treat this severe complication. PMID:23918215

  18. An Unusual Case of Extensive Lattice Degeneration and Retinal Detachment

    PubMed Central

    Sarma, Saurabh Kumar; Basaiawmoit, Jennifer V.

    2016-01-01

    Lattice degeneration of the retina is not infrequently encountered on a dilated retinal examination and many of them do not need any intervention. We report a case of atypical lattice degeneration variant with peripheral retinal detachment. An asymptomatic 35-year-old lady with minimal refractive error was found to have extensive lattice degeneration, peripheral retinal detachment and fibrotic changes peripherally with elevation of retinal vessels on dilated retinal examination. There were also areas of white without pressure, chorioretinal scarring and retinal breaks. All the changes were limited to beyond the equator but were found to span 360 degrees. She was treated with barrage laser all around to prevent extension of the retinal detachment posteriorly. She remained stable till her latest follow-up two years after the barrage laser. This case is reported for its rarity with a discussion of the probable differential diagnoses. To the best of our knowledge, this is the first report of such findings in lattice degeneration.

  19. Retinal vascular changes are a marker for cerebral vascular diseases

    PubMed Central

    Moss, Heather E.

    2016-01-01

    The retinal circulation is a potential marker of cerebral vascular disease because it shares origin and drainage with the intracranial circulation and because it can be directly visualized using ophthalmoscopy. Cross sectional and cohort studies have demonstrated associations between chronic retinal and cerebral vascular disease, acute retinal and cerebral vascular disease and chronic retinal vascular disease and acute cerebral vascular disease. In particular, certain qualitative features of retinopathy, retinal artery occlusion and increased retinal vein caliber are associated with concurrent and future cerebrovascular events. These associations persist after accounting for confounding variables known to be disease-causing in both circulations, which supports the potential use of retinal vasculature findings to stratify individuals with regards to cerebral vascular disease risk. PMID:26008809

  20. Reactive retinal microglia, neuronal survival and the formation of retinal folds and detachments

    PubMed Central

    Fischer, Andy J.; Zelinka, Christopher; Milani-Nejad, Nima

    2014-01-01

    Reactive microglia and macrophages are prevalent in damaged retinas. Accordingly, we investigate how the activation or ablation of microglia/macrophages influences the survival of neurons in the chick retina in vivo. We applied intraocular injections of interleukin 6 (IL6) to stimulate the reactivity of microglia/macrophages and clodronate-liposomes to ablate microglia/macrophages. Activation of the microglia/macrophages with IL6 delays the death of retinal neurons from N-methyl-D-aspartate (NMDA) -induced excitotoxicity. In addition, activation of microglia/macrophages combined with colchicine-mediated retinal damage diminished the survival of ganglion cells. Application of IL6 after an excitotoxic insult greatly exacerbates the damage, and causes widespread retinal detachments and folds, accompanied by accumulation of microglia/macrophages in the subretinal space. Damage-induced retinal folds and detachments were significantly reduced by the ablation of microglia/macrophages. We conclude that microglial reactivity is detrimental to the survival of ganglion cells in colchicine-damaged retinas and detrimental to the survival of photoreceptors in retinal folds. In addition, we conclude that IL6-treatment transiently protects amacrine and bipolar cells against an excitotoxic insult. We propose that suppressing reactivity of microglia/macrophages may be an effective means to lessen the damage and vision loss resulting from damage, in particular during retinal detachment injuries. PMID:25231952

  1. Relation of retinal blood flow and retinal oxygen extraction during stimulation with diffuse luminance flicker

    PubMed Central

    Palkovits, Stefan; Lasta, Michael; Told, Reinhard; Schmidl, Doreen; Werkmeister, René; Cherecheanu, Alina Popa; Garhöfer, Gerhard; Schmetterer, Leopold

    2015-01-01

    Cerebral and retinal blood flow are dependent on local neuronal activity. Several studies quantified the increase in cerebral blood flow and oxygen consumption during activity. In the present study we investigated the relation between changes in retinal blood flow and oxygen extraction during stimulation with diffuse luminance flicker and the influence of breathing gas mixtures with different fractions of O2 (FiO2; 100% 15% and 12%). Twenty-four healthy subjects were included. Retinal blood flow was studied by combining measurement of vessel diameters using the Dynamic Vessel Analyser with measurements of blood velocity using laser Doppler velocimetry. Oxygen saturation was measured using spectroscopic reflectometry and oxygen extraction was calculated. Flicker stimulation increased retinal blood flow (57.7 ± 17.8%) and oxygen extraction (34.6 ± 24.1%; p < 0.001 each). During 100% oxygen breathing the response of retinal blood flow and oxygen extraction was increased (p < 0.01 each). By contrast, breathing gas mixtures with 12% and 15% FiO2 did not alter flicker–induced retinal haemodynamic changes. The present study indicates that at a comparable increase in blood flow the increase in oxygen extraction in the retina is larger than in the brain. During systemic hyperoxia the blood flow and oxygen extraction responses to neural stimulation are augmented. The underlying mechanism is unknown. PMID:26672758

  2. Relation of retinal blood flow and retinal oxygen extraction during stimulation with diffuse luminance flicker.

    PubMed

    Palkovits, Stefan; Lasta, Michael; Told, Reinhard; Schmidl, Doreen; Werkmeister, René; Cherecheanu, Alina Popa; Garhöfer, Gerhard; Schmetterer, Leopold

    2015-01-01

    Cerebral and retinal blood flow are dependent on local neuronal activity. Several studies quantified the increase in cerebral blood flow and oxygen consumption during activity. In the present study we investigated the relation between changes in retinal blood flow and oxygen extraction during stimulation with diffuse luminance flicker and the influence of breathing gas mixtures with different fractions of O2 (FiO2; 100% 15% and 12%). Twenty-four healthy subjects were included. Retinal blood flow was studied by combining measurement of vessel diameters using the Dynamic Vessel Analyser with measurements of blood velocity using laser Doppler velocimetry. Oxygen saturation was measured using spectroscopic reflectometry and oxygen extraction was calculated. Flicker stimulation increased retinal blood flow (57.7 ± 17.8%) and oxygen extraction (34.6 ± 24.1%; p < 0.001 each). During 100% oxygen breathing the response of retinal blood flow and oxygen extraction was increased (p < 0.01 each). By contrast, breathing gas mixtures with 12% and 15% FiO2 did not alter flicker-induced retinal haemodynamic changes. The present study indicates that at a comparable increase in blood flow the increase in oxygen extraction in the retina is larger than in the brain. During systemic hyperoxia the blood flow and oxygen extraction responses to neural stimulation are augmented. The underlying mechanism is unknown. PMID:26672758

  3. Laser-induced retinal damage thresholds for annular retinal beam profiles

    NASA Astrophysics Data System (ADS)

    Kennedy, Paul K.; Zuclich, Joseph A.; Lund, David J.; Edsall, Peter R.; Till, Stephen; Stuck, Bruce E.; Hollins, Richard C.

    2004-07-01

    The dependence of retinal damage thresholds on laser spot size, for annular retinal beam profiles, was measured in vivo for 3 μs, 590 nm pulses from a flashlamp-pumped dye laser. Minimum Visible Lesion (MVL)ED50 thresholds in rhesus were measured for annular retinal beam profiles covering 5, 10, and 20 mrad of visual field; which correspond to outer beam diameters of roughly 70, 160, and 300 μm, respectively, on the primate retina. Annular beam profiles at the retinal plane were achieved using a telescopic imaging system, with the focal properties of the eye represented as an equivalent thin lens, and all annular beam profiles had a 37% central obscuration. As a check on experimental data, theoretical MVL-ED50 thresholds for annular beam exposures were calculated using the Thompson-Gerstman granular model of laser-induced thermal damage to the retina. Threshold calculations were performed for the three experimental beam diameters and for an intermediate case with an outer beam diameter of 230 μm. Results indicate that the threshold vs. spot size trends, for annular beams, are similar to the trends for top hat beams determined in a previous study; i.e., the threshold dose varies with the retinal image area for larger image sizes. The model correctly predicts the threshold vs. spot size trends seen in the biological data, for both annular and top hat retinal beam profiles.

  4. Aerobic exercise protects retinal function and structure from light-induced retinal degeneration.

    PubMed

    Lawson, Eric C; Han, Moon K; Sellers, Jana T; Chrenek, Micah A; Hanif, Adam; Gogniat, Marissa A; Boatright, Jeffrey H; Pardue, Machelle T

    2014-02-12

    Aerobic exercise is a common intervention for rehabilitation of motor, and more recently, cognitive function (Intlekofer and Cotman, 2013; Wood et al., 2012). While the underlying mechanisms are complex, BDNF may mediate much of the beneficial effects of exercise to these neurons (Ploughman et al., 2007; Griffin et al., 2011; Real et al., 2013). We studied the effects of aerobic exercise on retinal neurons undergoing degeneration. We exercised wild-type BALB/c mice on a treadmill (10 m/min for 1 h) for 5 d/week or placed control mice on static treadmills. After 2 weeks of exercise, mice were exposed to either toxic bright light (10,000 lux) for 4 h to induce photoreceptor degeneration or maintenance dim light (25 lux). Bright light caused 75% loss of both retinal function and photoreceptor numbers. However, exercised mice exposed to bright light had 2 times greater retinal function and photoreceptor nuclei than inactive mice exposed to bright light. In addition, exercise increased retinal BDNF protein levels by 20% compared with inactive mice. Systemic injections of a BDNF tropomyosin-receptor-kinase (TrkB) receptor antagonist reduced retinal function and photoreceptor nuclei counts in exercised mice to inactive levels, effectively blocking the protective effects seen with aerobic exercise. The data suggest that aerobic exercise is neuroprotective for retinal degeneration and that this effect is mediated by BDNF signaling. PMID:24523530

  5. The genomic response of the retinal pigment epithelium to light damage and retinal detachment

    PubMed Central

    Rattner, Amir; Toulabi, Leila; Williams, John; Yu, Huimin; Nathans, Jeremy

    2008-01-01

    The retinal pigment epithelium (RPE) plays an essential role in maintaining the health of the retina. The RPE is also the site of pathologic processes in a wide variety of retinal disorders including monogenic retinal dystrophies, age-related macular degeneration, and retinal detachment. Despite intense interest in the RPE, little is known about its molecular response to ocular damage or disease. We have conducted a comprehensive analysis of changes in transcript abundance (the “genomic response”) in the murine RPE following light damage. Several dozen transcripts, many related to cell-cell signaling, show significant increases in abundance in response to bright light; transcripts encoding visual cycle proteins show a decrease in abundance. Similar changes are induced by retinal detachment. Environmental and genetic perturbations that modulate the RPE response to bright light suggest that this response is controlled by the retina. In contrast to the response to bright light, the RPE response to retinal detachment over-rides these modulatory affects. PMID:18815272

  6. Retinal microvascular abnormalities and subclinical magnetic resonance imaging brain infarct: a prospective study

    PubMed Central

    Cheung, Ning; Mosley, Thomas; Islam, Amirul; Kawasaki, Ryo; Sharrett, A. Richey; Klein, Ronald; Coker, Laura H.; Knopman, David S.; Shibata, Dean K.; Catellier, Diane

    2010-01-01

    ratio 2.12; 95% confidence interval: 1.18–3.81) and progression (odds ratio 2.22; 95% confidence interval: 1.00–5.88). In conclusion, retinal microvascular abnormalities are associated with emergence of subclinical magnetic resonance imaging brain infarcts and white matter lesions, independent of shared risk factors. Retinal vascular imaging may offer a non-invasive tool to investigate the pathogenesis and natural history of cerebral small-vessel disease. PMID:20519327

  7. VSX2 and ASCL1 Are Indicators of Neurogenic Competence in Human Retinal Progenitor Cultures.

    PubMed

    Wright, Lynda S; Pinilla, Isabel; Saha, Jishnu; Clermont, Joshua M; Lien, Jessica S; Borys, Katarzyna D; Capowski, Elizabeth E; Phillips, M Joseph; Gamm, David M

    2015-01-01

    Three dimensional (3D) culture techniques are frequently used for CNS tissue modeling and organoid production, including generation of retina-like tissues. A proposed advantage of these 3D systems is their potential to more closely approximate in vivo cellular microenvironments, which could translate into improved manufacture and/or maintenance of neuronal populations. Visual System Homeobox 2 (VSX2) labels all multipotent retinal progenitor cells (RPCs) and is known to play important roles in retinal development. In contrast, the proneural transcription factor Acheate scute-like 1 (ASCL1) is expressed transiently in a subset of RPCs, but is required for the production of most retinal neurons. Therefore, we asked whether the presence of VSX2 and ASCL1 could gauge neurogenic potential in 3D retinal cultures derived from human prenatal tissue or ES cells (hESCs). Short term prenatal 3D retinal cultures displayed multiple characteristics of human RPCs (hRPCs) found in situ, including robust expression of VSX2. Upon initiation of hRPC differentiation, there was a small increase in co-labeling of VSX2+ cells with ASCL1, along with a modest increase in the number of PKCα+ neurons. However, 3D prenatal retinal cultures lost expression of VSX2 and ASCL1 over time while concurrently becoming refractory to neuronal differentiation. Conversely, 3D optic vesicles derived from hESCs (hESC-OVs) maintained a robust VSX2+ hRPC population that could spontaneously co-express ASCL1 and generate photoreceptors and other retinal neurons for an extended period of time. These results show that VSX2 and ASCL1 can serve as markers for neurogenic potential in cultured hRPCs. Furthermore, unlike hESC-OVs, maintenance of 3D structure does not independently convey an advantage in the culture of prenatal hRPCs, further illustrating differences in the survival and differentiation requirements of hRPCs extracted from native tissue vs. those generated entirely in vitro. PMID:26292211

  8. A Psychophysical Test for Retinitis Pigmentosa.

    ERIC Educational Resources Information Center

    Corwin, Thomas R; Mancini, Michael

    A new test designed to detect an hereditary eye disease called retinitis pigmentosa (RP) is described. This condition is revealed by pigmentation in the retina, but early diagnosis is difficult because the symptoms are subtle, and since it is genetically recessive it frequently occurs in families with no history of early blindness. In many cases…

  9. The Retinitis Pigmentosa Student: Selected Aspects.

    ERIC Educational Resources Information Center

    Sullivan, Franklin N.

    1984-01-01

    The characteristic features of RP (retinitis pigmentosa-an untreatable conditions usually resulting in night blindness) are discussed and functioning considerations in the classroom (including the use of protective devices and mobility aids) are noted. Classroom modifications such as darklined paper and black pens are suggested. (CL)

  10. Unsupervised Retinal Vessel Segmentation Using Combined Filters

    PubMed Central

    Oliveira, Wendeson S.; Teixeira, Joyce Vitor; Ren, Tsang Ing; Cavalcanti, George D. C.; Sijbers, Jan

    2016-01-01

    Image segmentation of retinal blood vessels is a process that can help to predict and diagnose cardiovascular related diseases, such as hypertension and diabetes, which are known to affect the retinal blood vessels’ appearance. This work proposes an unsupervised method for the segmentation of retinal vessels images using a combined matched filter, Frangi’s filter and Gabor Wavelet filter to enhance the images. The combination of these three filters in order to improve the segmentation is the main motivation of this work. We investigate two approaches to perform the filter combination: weighted mean and median ranking. Segmentation methods are tested after the vessel enhancement. Enhanced images with median ranking are segmented using a simple threshold criterion. Two segmentation procedures are applied when considering enhanced retinal images using the weighted mean approach. The first method is based on deformable models and the second uses fuzzy C-means for the image segmentation. The procedure is evaluated using two public image databases, Drive and Stare. The experimental results demonstrate that the proposed methods perform well for vessel segmentation in comparison with state-of-the-art methods. PMID:26919587

  11. Unsupervised Retinal Vessel Segmentation Using Combined Filters.

    PubMed

    Oliveira, Wendeson S; Teixeira, Joyce Vitor; Ren, Tsang Ing; Cavalcanti, George D C; Sijbers, Jan

    2016-01-01

    Image segmentation of retinal blood vessels is a process that can help to predict and diagnose cardiovascular related diseases, such as hypertension and diabetes, which are known to affect the retinal blood vessels' appearance. This work proposes an unsupervised method for the segmentation of retinal vessels images using a combined matched filter, Frangi's filter and Gabor Wavelet filter to enhance the images. The combination of these three filters in order to improve the segmentation is the main motivation of this work. We investigate two approaches to perform the filter combination: weighted mean and median ranking. Segmentation methods are tested after the vessel enhancement. Enhanced images with median ranking are segmented using a simple threshold criterion. Two segmentation procedures are applied when considering enhanced retinal images using the weighted mean approach. The first method is based on deformable models and the second uses fuzzy C-means for the image segmentation. The procedure is evaluated using two public image databases, Drive and Stare. The experimental results demonstrate that the proposed methods perform well for vessel segmentation in comparison with state-of-the-art methods. PMID:26919587

  12. CERKL Knockdown Causes Retinal Degeneration in Zebrafish

    PubMed Central

    Riera, Marina; Burguera, Demian; Garcia-Fernàndez, Jordi; Gonzàlez-Duarte, Roser

    2013-01-01

    The human CERKL gene is responsible for common and severe forms of retinal dystrophies. Despite intense in vitro studies at the molecular and cellular level and in vivo analyses of the retina of murine knockout models, CERKL function remains unknown. In this study, we aimed to approach the developmental and functional features of cerkl in Danio rerio within an Evo-Devo framework. We show that gene expression increases from early developmental stages until the formation of the retina in the optic cup. Unlike the high mRNA-CERKL isoform multiplicity shown in mammals, the moderate transcriptional complexity in fish facilitates phenotypic studies derived from gene silencing. Moreover, of relevance to pathogenicity, teleost CERKL shares the two main human protein isoforms. Morpholino injection has been used to generate a cerkl knockdown zebrafish model. The morphant phenotype results in abnormal eye development with lamination defects, failure to develop photoreceptor outer segments, increased apoptosis of retinal cells and small eyes. Our data support that zebrafish Cerkl does not interfere with proliferation and neural differentiation during early developmental stages but is relevant for survival and protection of the retinal tissue. Overall, we propose that this zebrafish model is a powerful tool to unveil CERKL contribution to human retinal degeneration. PMID:23671706

  13. Changes in ganglion cells during retinal degeneration.

    PubMed

    Saha, Susmita; Greferath, Ursula; Vessey, Kirstan A; Grayden, David B; Burkitt, Anthony N; Fletcher, Erica L

    2016-08-01

    Inherited retinal degeneration such as retinitis pigmentosa (RP) is associated with photoreceptor loss and concomitant morphological and functional changes in the inner retina. It is not known whether these changes are associated with changes in the density and distribution of synaptic inputs to retinal ganglion cells (RGCs). We quantified changes in ganglion cell density in rd1 and age-matched C57BL/6J-(wildtype, WT) mice using the immunocytochemical marker, RBPMS. Our data revealed that following complete loss of photoreceptors, (∼3months of age), there was a reduction in ganglion cell density in the peripheral retina. We next examined changes in synaptic inputs to A type ganglion cells by performing double labeling experiments in mice with the ganglion cell reporter lines, rd1-Thy1 and age-matched wildtype-Thy1. Ribbon synapses were identified by co-labelling with CtBP2 (RIBEYE) and conventional synapses with the clustering molecule, gephyrin. ON RGCs showed a significant reduction in RIBEYE-immunoreactive synapse density while OFF RGCs showed a significant reduction in the gephyrin-immmunoreactive synapse density. Distribution patterns of both synaptic markers across the dendritic trees of RGCs were unchanged. The change in synaptic inputs to RGCs was associated with a reduction in the number of immunolabeled rod bipolar and ON cone bipolar cells. These results suggest that functional changes reported in ganglion cells during retinal degeneration could be attributed to loss of synaptic inputs. PMID:27132232

  14. Connexin43 in retinal injury and disease.

    PubMed

    Danesh-Meyer, Helen V; Zhang, Jie; Acosta, Monica L; Rupenthal, Ilva D; Green, Colin R

    2016-03-01

    Gap junctions are specialized cell-to-cell contacts that allow the direct transfer of small molecules between cells. A single gap junction channel consists of two hemichannels, or connexons, each of which is composed of six connexin protein subunits. Connexin43 is the most ubiquitously expressed isoform of the connexin family and in the retina it is prevalent in astrocytes, Müller cells, microglia, retinal pigment epithelium and endothelial cells. Prior to docking with a neighboring cell, Connexin43 hemichannels have a low open probability as open channels constitute a large, relatively non-specific membrane pore. However, with injury and disease Connexin43 upregulation and hemichannel opening has been implicated in all aspects of secondary damage, especially glial cell activation, edema and loss of vascular integrity, leading to neuronal death. We here review gap junctions and their roles in the retina, and then focus in on Connexin43 gap junction channels in injury and disease. In particular, the effect of pathological opening of gap junction hemichannels is described, and hemichannel mediated loss of vascular integrity explained. This latter phenomenon underlies retinal pigment epithelium loss and is a common feature in several retinal diseases. Finally, Connexin43 channel roles in a number of retinal diseases including macular degeneration, glaucoma and diabetic retinopathy are considered, along with results from related animal models. A final section describes gap junction channel modulation and the ocular delivery of potential therapeutic molecules. PMID:26432657

  15. a Review of Retinal Prosthesis Approaches

    NASA Astrophysics Data System (ADS)

    Kien, Tran Trung; Maul, Tomas; Bargiela, Andrzej

    Age-related macular degeneration and retinitis pigmentosa are two of the most common diseases that cause degeneration in the outer retina, which can lead to several visual impairments up to blindness. Vision restoration is an important goal for which several different research approaches are currently being pursued. We are concerned with restoration via retinal prosthetic devices. Prostheses can be implemented intraocularly and extraocularly, which leads to different categories of devices. Cortical Prostheses and Optic Nerve Prostheses are examples of extraocular solutions while Epiretinal Prostheses and Subretinal Prostheses are examples of intraocular solutions. Some of the prostheses that are successfully implanted and tested in animals as well as humans can restore basic visual functions but still have limitations. This paper will give an overview of the current state of art of Retinal Prostheses and compare the advantages and limitations of each type. The purpose of this review is thus to summarize the current technologies and approaches used in developing Retinal Prostheses and therefore to lay a foundation for future designs and research directions.

  16. Nanoengineering of therapeutics for retinal vascular disease.

    PubMed

    Gahlaut, Nivriti; Suarez, Sandra; Uddin, Md Imam; Gordon, Andrew Y; Evans, Stephanie M; Jayagopal, Ashwath

    2015-09-01

    Retinal vascular diseases, including diabetic retinopathy, neovascular age related macular degeneration, and retinal vein occlusion, are leading causes of blindness in the Western world. These diseases share several common disease mechanisms, including vascular endothelial growth factor (VEGF) signaling, hypoxia, and inflammation, which provide opportunities for common therapeutic strategies. Treatment of these diseases using laser therapy, anti-VEGF injections, and/or steroids has significantly improved clinical outcomes. However, these strategies do not address the underlying root causes of pathology, and may have deleterious side effects. Furthermore, many patients continue to progress toward legal blindness despite receiving regular therapy. Nanomedicine, the engineering of therapeutics at the 1-100 nm scale, is a promising approach for improving clinical management of retinal vascular diseases. Nanomedicine-based technologies have the potential to revolutionize the treatment of ophthalmology, through enabling sustained release of drugs over several months, reducing side effects due to specific targeting of dysfunctional cells, and interfacing with currently "undruggable" targets. We will discuss emerging nanomedicine-based applications for the treatment of complications associated with retinal vascular diseases, including angiogenesis and inflammation. PMID:26022642

  17. Retinal pigment epithelial hamartoma--unusual manifestations.

    PubMed Central

    Rosenberg, P. R.; Walsh, J. B.

    1984-01-01

    Hamartoma of the retinal pigment epithelium is an uncommon tumour of young adults. We have seen 2 patients with this clinical diagnosis, both with unusual manifestations. In one patient growth of the tumour was observed over a 5-year period. In the second patient arterial-arterial anastomoses were detected at a site distal to the tumour. Images PMID:6722077

  18. Retinal Imaging Techniques for Diabetic Retinopathy Screening.

    PubMed

    Goh, James Kang Hao; Cheung, Carol Y; Sim, Shaun Sebastian; Tan, Pok Chien; Tan, Gavin Siew Wei; Wong, Tien Yin

    2016-03-01

    Due to the increasing prevalence of diabetes mellitus, demand for diabetic retinopathy (DR) screening platforms is steeply increasing. Early detection and treatment of DR are key public health interventions that can greatly reduce the likelihood of vision loss. Current DR screening programs typically employ retinal fundus photography, which relies on skilled readers for manual DR assessment. However, this is labor-intensive and suffers from inconsistency across sites. Hence, there has been a recent proliferation of automated retinal image analysis software that may potentially alleviate this burden cost-effectively. Furthermore, current screening programs based on 2-dimensional fundus photography do not effectively screen for diabetic macular edema (DME). Optical coherence tomography is becoming increasingly recognized as the reference standard for DME assessment and can potentially provide a cost-effective solution for improving DME detection in large-scale DR screening programs. Current screening techniques are also unable to image the peripheral retina and require pharmacological pupil dilation; ultra-widefield imaging and confocal scanning laser ophthalmoscopy, which address these drawbacks, possess great potential. In this review, we summarize the current DR screening methods using various retinal imaging techniques, and also outline future possibilities. Advances in retinal imaging techniques can potentially transform the management of patients with diabetes, providing savings in health care costs and resources. PMID:26830491

  19. Prospectives for Gene Therapy of Retinal Degenerations

    PubMed Central

    Thumann, Gabriele

    2012-01-01

    Retinal degenerations encompass a large number of diseases in which the retina and associated retinal pigment epithelial (RPE) cells progressively degenerate leading to severe visual disorders or blindness. Retinal degenerations can be divided into two groups, a group in which the defect has been linked to a specific gene and a second group that has a complex etiology that includes environmental and genetic influences. The first group encompasses a number of relatively rare diseases with the most prevalent being Retinitis pigmentosa that affects approximately 1 million individuals worldwide. Attempts have been made to correct the defective gene by transfecting the appropriate cells with the wild-type gene and while these attempts have been successful in animal models, human gene therapy for these inherited retinal degenerations has only begun recently and the results are promising. To the second group belong glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). These retinal degenerations have a genetic component since they occur more often in families with affected probands but they are also linked to environmental factors, specifically elevated intraocular pressure, age and high blood sugar levels respectively. The economic and medical impact of these three diseases can be assessed by the number of individuals affected; AMD affects over 30 million, DR over 40 million and glaucoma over 65 million individuals worldwide. The basic defect in these diseases appears to be the relative lack of a neurogenic environment; the neovascularization that often accompanies these diseases has suggested that a decrease in pigment epithelium-derived factor (PEDF), at least in part, may be responsible for the neurodegeneration since PEDF is not only an effective neurogenic and neuroprotective agent but also a potent inhibitor of neovascularization. In the last few years inhibitors of vascularization, especially antibodies against vascular endothelial cell

  20. 46 CFR 28.830 - Fire detection system.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... must be equipped with an independent modular smoke detector or a smoke actuated fire detecting unit installed in accordance with § 76.33 of this chapter. (b) An independent modular smoke detector must meet UL 217 and be listed as a “Single Station Smoke Detector—Also Suitable for Use in Recreational Vehicles”....

  1. 46 CFR 28.830 - Fire detection system.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... must be equipped with an independent modular smoke detector or a smoke actuated fire detecting unit installed in accordance with § 76.33 of this chapter. (b) An independent modular smoke detector must meet UL 217 and be listed as a “Single Station Smoke Detector—Also Suitable for Use in Recreational Vehicles”....

  2. 46 CFR 28.830 - Fire detection system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... must be equipped with an independent modular smoke detector or a smoke actuated fire detecting unit installed in accordance with § 76.33 of this chapter. (b) An independent modular smoke detector must meet UL 217 and be listed as a “Single Station Smoke Detector—Also Suitable for Use in Recreational Vehicles”....

  3. 46 CFR 28.830 - Fire detection system.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... must be equipped with an independent modular smoke detector or a smoke actuated fire detecting unit installed in accordance with § 76.33 of this chapter. (b) An independent modular smoke detector must meet UL 217 and be listed as a “Single Station Smoke Detector—Also Suitable for Use in Recreational Vehicles”....

  4. 46 CFR 28.830 - Fire detection system.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... must be equipped with an independent modular smoke detector or a smoke actuated fire detecting unit installed in accordance with § 76.33 of this chapter. (b) An independent modular smoke detector must meet UL 217 and be listed as a “Single Station Smoke Detector—Also Suitable for Use in Recreational Vehicles”....

  5. Cytomegalovirus retinitis after central retinal vein occlusion in a patient on systemic immunosuppression: does venooclusive disease predispose to cytomegalovirus retinitis in patients already at risk?

    PubMed Central

    Welling, John D; Tarabishy, Ahmad B; Christoforidis, John B

    2012-01-01

    Cytomegalovirus (CMV) retinitis remains the most common opportunistic ocular infection in immunocompromised patients. Patients with immunocompromising diseases, such as acquired immunodeficiency syndrome, inherited immunodeficiency states, malignancies, and those on systemic immunosuppressive therapy, are known to be at risk. Recently, it has been suggested that patients undergoing intravitreal injection of immunosuppressive agents may also be predisposed. One previous case report speculated that there may be an additional risk for CMV retinitis in acquired immunodeficiency syndrome patients with venoocclusive disease. This case study presents a case of CMV retinitis following central retinal vein occlusion in a patient on systemic immunosuppressants. PMID:22570539

  6. Dye-Free Porcine Model of Experimental Branch Retinal Vein Occlusion: A Suitable Approach for Retinal Proteomics

    PubMed Central

    Jørgensen Cehofski, Lasse; Kruse, Anders; Kjærgaard, Benedict; Stensballe, Allan; Honoré, Bent; Vorum, Henrik

    2015-01-01

    Branch retinal vein occlusion induces complex biological processes in the retina that are generated by a multitude of interacting proteins. These proteins and their posttranslational modifications can effectively be studied using modern proteomic techniques. However, no method for studying large-scale protein changes following branch retinal vein occlusion has been available until now. Obtainment of retinal tissue exposed to branch retinal vein occlusion is only available through experimental animal models. Traditional models of experimental branch retinal vein occlusion require the use of Rose Bengal dye combined with argon laser photocoagulation. The use of Rose Bengal dye is problematic in proteomic studies as the dye can induce multiple protein modifications when irradiated. This paper presents a novel technique for proteomic analysis of porcine retinal tissue with branch retinal vein occlusion combining a dye-free experimental model with label-free liquid chromatography mass spectrometry based proteomics. PMID:26064675

  7. Independence Generalizing Monotone and Boolean Independences

    NASA Astrophysics Data System (ADS)

    Hasebe, Takahiro

    2011-01-01

    We define conditionally monotone independence in two states which interpolates monotone and Boolean ones. This independence is associative, and therefore leads to a natural probability theory in a non-commutative algebra.

  8. A forest-fire model with natural fire resistance

    NASA Astrophysics Data System (ADS)

    Yoder, M. R.; Turcotte, D. L.; Rundle, J. B.; Glasscoe, M. T.; Donnellan, A.

    2010-12-01

    It is widely believed that contemporary wildfire suppression practices in the United States have contributed to conditions that facilitate large, destructive fires. We introduce a forest-fire model with natural fire-resistance that supports this theory. The model yields power-law frequency-size distributions of model fires with scaling exponent values 1.2 ≤ b ≤ 1.75, consistent with distributions of wildfires observed in the United States. We show a direct relationship between a fire's intensity and its burn area, and we show that aggressive suppression of small early season fires can compromise a region's natural fire-resistance, increasing the rate of large fires.

  9. Photovoltaic retinal prosthesis: implant fabrication and performance

    NASA Astrophysics Data System (ADS)

    Wang, Lele; Mathieson, K.; Kamins, T. I.; Loudin, J. D.; Galambos, L.; Goetz, G.; Sher, A.; Mandel, Y.; Huie, P.; Lavinsky, D.; Harris, J. S.; Palanker, D. V.

    2012-08-01

    The objective of this work is to develop and test a photovoltaic retinal prosthesis for restoring sight to patients blinded by degenerative retinal diseases. A silicon photodiode array for subretinal stimulation has been fabricated by a silicon-integrated-circuit/MEMS process. Each pixel in the two-dimensional array contains three series-connected photodiodes, which photovoltaically convert pulsed near-infrared light into bi-phasic current to stimulate nearby retinal neurons without wired power connections. The device thickness is chosen to be 30 µm to absorb a significant portion of light while still being thin enough for subretinal implantation. Active and return electrodes confine current near each pixel and are sputter coated with iridium oxide to enhance charge injection levels and provide a stable neural interface. Pixels are separated by 5 µm wide trenches to electrically isolate them and to allow nutrient diffusion through the device. Three sizes of pixels (280, 140 and 70 µm) with active electrodes of 80, 40 and 20 µm diameter were fabricated. The turn-on voltages of the one-diode, two-series-connected diode and three-series-connected diode structures are approximately 0.6, 1.2 and 1.8 V, respectively. The measured photo-responsivity per diode at 880 nm wavelength is ˜0.36 A W-1, at zero voltage bias and scales with the exposed silicon area. For all three pixel sizes, the reverse-bias dark current is sufficiently low (<100 pA) for our application. Pixels of all three sizes reliably elicit retinal responses at safe near-infrared light irradiances, with good acceptance of the photodiode array in the subretinal space. The fabricated device delivers efficient retinal stimulation at safe near-infrared light irradiances without any wired power connections, which greatly simplifies the implantation procedure. Presence of the return electrodes in each pixel helps to localize the current, and thereby improves resolution.

  10. Retinal and Choroidal Folds in Papilledema

    PubMed Central

    Sibony, Patrick A.; Kupersmith, Mark J.; Feldon, Steven E.; Wang, Jui-Kai; Garvin, Mona

    2015-01-01

    Purpose To determine the frequency, patterns, associations, and biomechanical implications of retinal and choroidal folds in papilledema due to idiopathic intracranial hypertension (IIH). Methods Retinal and choroidal folds were studied in patients enrolled in the IIH Treatment Trial using fundus photography (n = 165 study eyes) and spectral-domain optical coherence tomography (SD-OCT; n = 125). We examined the association between folds and peripapillary shape, retinal nerve fiber layer (RNFL) thickness, disc volume, Frisén grade, acuity, perimetric mean deviation, intraocular pressure, intracranial pressure, and refractive error. Results We identified three types of folds in IIH patients with papilledema: peripapillary wrinkles (PPW), retinal folds (RF), and choroidal folds (CF). Frequency, with photos, was 26%, 19%, and 1%, respectively; SD-OCT frequency was 46%, 47%, and 10%. At least one type of fold was present in 41% of patients with photos and 73% with SD-OCT. Spectral-domain OCT was more sensitive. Structural parameters related to the severity of papilledema were associated with PPW and RF, whereas anterior deformation of the peripapillary RPE/basement membrane layer was associated with CF and RF. Folds were not associated with vision loss at baseline. Conclusions Folds in papilledema are biomechanical signs of stress/strain on the optic nerve head and load-bearing structures induced by intracranial hypertension. Folds are best imaged with SD-OCT. The patterns of retinal and choroidal folds are the products of a complex interplay between the degree of papilledema and anterior deformation of the load-bearing structures (sclera and possibly the lamina cribrosa), both modulated by structural geometry and material properties of the optic nerve head. (ClinicalTrials.gov number, NCT01003639.) PMID:26335066

  11. Retinal image quality, reading and myopia.

    PubMed

    Collins, Michael J; Buehren, Tobias; Iskander, D Robert

    2006-01-01

    Analysis was undertaken of the retinal image characteristics of the best-spectacle corrected eyes of progressing myopes (n = 20, mean age = 22 years; mean spherical equivalent = -3.84 D) and a control group of emmetropes (n = 20, mean age = 23 years; mean spherical equivalent = 0.00 D) before and after a 2h reading task. Retinal image quality was calculated based upon wavefront measurements taken with a Hartmann-Shack sensor with fixation on both a far (5.5 m) and near (individual reading distance) target. The visual Strehl ratio based on the optical transfer function (VSOTF) was significantly worse for the myopes prior to reading for both the far (p = 0.01) and near (p = 0.03) conditions. The myopic group showed significant reductions in various aspects of retinal image quality compared with the emmetropes, involving components of the modulation transfer function, phase transfer function and point spread function, often along the vertical meridian of the eye. The depth of focus of the myopes (0.54 D) was larger (p = 0.02) than the emmetropes (0.42 D) and the distribution of refractive power (away from optimal sphero-cylinder) was greater in the myopic eyes (variance of distributions p < 0.05). We found evidence that the lead and lag of accommodation are influenced by the higher order aberrations of the eye (e.g. significant correlations between lead/lag and the peak of the visual Strehl ratio based on the MTF). This could indicate that the higher accommodation lags seen in myopes are providing optimized retinal image characteristics. The interaction between low and high order aberrations of the eye play a significant role in reducing the retinal image quality of myopic eyes compared with emmetropes. PMID:15913701

  12. Redundant safety features in a high-channel-count retinal neurostimulator

    PubMed Central

    Kelly, Shawn K.; Ellersick, William F.; Krishnan, Ashwati; Doyle, Patrick; Shire, Douglas B.; Wyatt, John L.; Rizzo, Joseph F.

    2016-01-01

    Safety features embedded in a 256-channel retinal prosthesis integrated circuit are presented. The biology of the retina and the electrochemistry of the electrode-tissue interface demand careful planning and design of the safety features of an implantable retinal stimulation device. We describe the internal limits and communication safety features of our ASIC, but we focus on monitoring and protection circuits for the electrode-tissue interface. Two independent voltage monitoring circuits for each channel measure the electrode polarization voltage at two different times in the biphasic stimulation cycle. The monitors ensure that the charged electrode stays within the electrochemical water window potentials, and that the discharged electrode is within a small window near the counter electrode potential. A switch to connect each electrode to the counter electrode between pulses protects against a wide range of device failures. Additionally, we describe work on an active feedback system to ensure that the electrode voltage is at zero.

  13. Fire-Retardant, Decorative Inks

    NASA Technical Reports Server (NTRS)

    Kourtides, D.; Nir, Z.; Mikroyannidis, J.

    1987-01-01

    Effectiveness of fire-retardant additives evaluated. Fire retardance of decorative acrylic printing inks for aircraft interiors enhanced by certain commercial and experimental fire-retardant additives, according to study.

  14. NASA Fire Protection Coordinators' Conference

    NASA Technical Reports Server (NTRS)

    Clark, Theodore

    2001-01-01

    Fire prevention activities at NASA's Stennis Space Center are reviewed in this viewgraph presentation. The Fire Prevention Office of the Fire Department at NASA Stennis conducts inspections and issues small appliance permits, while the Operations Section responds to emergencies.

  15. Total Approach to Fire Safety.

    ERIC Educational Resources Information Center

    Burgener, Edward

    1979-01-01

    A study completed by the fire department of the City of Winnipeg has documented the effectiveness of smoke detectors in reducing fire losses. The entire Winnipeg fire prevention program is described. (MLF)

  16. Retinal Prosthesis System for Advanced Retinitis Pigmentosa: A Health Technology Assessment

    PubMed Central

    2016-01-01

    Background Retinitis pigmentosa is a group of genetic disorders that involves the breakdown and loss of photoreceptors in the retina, resulting in progressive retinal degeneration and eventual blindness. The Argus II Retinal Prosthesis System is the only currently available surgical implantable device approved by Health Canada. It has been shown to improve visual function in patients with severe visual loss from advanced retinitis pigmentosa. The objective of this analysis was to examine the clinical effectiveness, cost-effectiveness, budget impact, and safety of the Argus II system in improving visual function, as well as exploring patient experiences with the system. Methods We performed a systematic search of the literature for studies examining the effects of the Argus II retinal prosthesis system in patients with advanced retinitis pigmentosa, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on visual function, functional outcomes, quality of life, and adverse events. We developed a Markov decision-analytic model to assess the cost-effectiveness of the Argus II system compared with standard care over a 10-year time horizon. We also conducted a 5-year budget impact analysis. We used a qualitative design and an interview methodology to examine patients’ lived experience, and we used a modified grounded theory methodology to analyze information from interviews. Transcripts were coded, and themes were compared against one another. Results One multicentre international study and one single-centre study were included in the clinical review. In both studies, patients showed improved visual function with the Argus II system. However, the sight-threatening surgical complication rate was substantial. In the base-case analysis, the Argus II system was cost-effective compared with standard care only if willingness-to-pay was more than $207,616 per quality-adjusted life

  17. Industrial Fire Brigade Training.

    ERIC Educational Resources Information Center

    North Carolina State Dept. of Community Colleges, Raleigh.

    Organized as a teaching outline for an industrial plant fire brigade course, this manual contains a rationale for an industrial plant brigade as an adjunct to the local firefighting services; information to the instructor concerning the implementation of an industrial fire brigade program; and a teaching outline consisting of eleven sections: (1)…

  18. Fossil-Fired Boilers

    Energy Science and Technology Software Center (ESTSC)

    1993-09-23

    Boiler Performance Model (BPM 3.0S) is a set of computer programs developed to analyze the performance of fossil-fired utility boilers. The programs can model a wide variety of boiler designs, and can model coal, oil, or natural gas firing. The programs are intended for use by engineers performing analyses of alternative fuels, alternative operating modes, or boiler modifications.

  19. Chisholm Forest Fire

    Atmospheric Science Data Center

    2013-04-17

    ... Larger Image A new look at smoke from the Chisholm forest fire, which ignited on May 23, 2001 about 160 kilometers north of ... in detail by M. Fromm and R. Servranckx, "Transport of forest fire smoke above the tropopause by supercell convection", Geophys. Res. ...

  20. Improving the representation of fire disturbance in dynamic vegetation models by assimilating satellite data

    NASA Astrophysics Data System (ADS)

    Kantzas, E. P.; Quegan, S.; Lomas, M.

    2015-03-01

    Fire provides an impulsive and stochastic pathway for carbon from the terrestrial biosphere to enter the atmosphere. Despite fire emissions being of similar magnitude to Net Ecosystem Exchange in many biomes, even the most complex Dynamic Vegetation Models (DVMs) embedded in General Circulation Models contain poor representations of fire behaviour and dynamics such as propagation and distribution of fire sizes. A model-independent methodology is developed which addresses this issue. Its focus is on the Arctic where fire is linked to permafrost dynamics and on occasion can release great amounts of carbon from carbon-rich organic soils. Connected Component Labeling is used to identify individual fire events across Canada and Russia from daily, low-resolution burned area satellite products, and the results are validated against historical data. This allows the creation of a fire database holding information on area burned and temporal evolution of fires in space and time. A method of assimilating the statistical distribution of fire area into a DVM whilst maintaining its Fire Return Interval is then described. The algorithm imposes a regional scale spatially dependent fire regime on a sub-scale spatially independent model (point model); the fire regime is described by large scale statistical distributions of fire intensity and spatial extent, and the temporal dynamics (fire return intervals) are determined locally. This permits DVMs to estimate many aspects of post-fire dynamics that cannot occur under their current representations of fire, as is illustrated by considering the evolution of land cover, biomass and Net Ecosystem Exchange after a fire.

  1. Optimal firing rate estimation

    NASA Technical Reports Server (NTRS)

    Paulin, M. G.; Hoffman, L. F.

    2001-01-01

    We define a measure for evaluating the quality of a predictive model of the behavior of a spiking neuron. This measure, information gain per spike (Is), indicates how much more information is provided by the model than if the prediction were made by specifying the neuron's average firing rate over the same time period. We apply a maximum Is criterion to optimize the performance of Gaussian smoothing filters for estimating neural firing rates. With data from bullfrog vestibular semicircular canal neurons and data from simulated integrate-and-fire neurons, the optimal bandwidth for firing rate estimation is typically similar to the average firing rate. Precise timing and average rate models are limiting cases that perform poorly. We estimate that bullfrog semicircular canal sensory neurons transmit in the order of 1 bit of stimulus-related information per spike.

  2. Fires in Chile

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On February 5, 2002, the dense smoke from numerous forest fires stretched out over the Pacific Ocean about 400 miles south of Santiago, Chile. This true-color Moderate-resolution Imaging Spectroradiometer (MODIS) image shows the fires, which are located near the city of Temuco. The fires are indicated with red dots (boxes in the high-resolution imagery). The fires were burning near several national parks and nature reserves in an area of the Chilean Andes where tourism is very popular. Southeast of the fires, the vegetation along the banks of the Rio Negro in Argentina stands out in dark green. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  3. [Fire worship on Soratte: form prehistory to present days].

    PubMed

    Falchetti, Mario; Ottini, Laura

    2013-01-01

    Fire has always been involved in human thoughts, believes and actions. For many psychological reasons fire has been considered as living power: red as the human blood, warm as the human body, clearly shines in the night. Fire worship is very common, especially in regions where terrestrial fire is believed to be the image of the heavenly fire. Fire worship has represented the base for symbolic systems involved in the cultural-anthropological evolution of populations settled close to mount Soratte. Fire cults in this region have originated in independent and long-time separated contexts, according to available knowledge. Hirpi Sorani, ancient inhabitants of mount Soratte territory, celebrated Sorano Apollo by a famous fire walking ceremony, with a likely cathartic and apotropaic meaning, as reported by ancient Roman writers. The victory of Christianity over paganism caused the decline of these religious practices. The beginning of the XIX century witnessed the establishment ofa new kind of devotion to the Virgin Mary at the mount Soratte. Today, this religious piety-linked identity has weakened due to changes in lifestyles,from an agricultural to one based on outside home employment, and has been largely shifted on cultural and anthropological bases. In conclusion, fire worship at mount Soratte has evolved because of external influences and local inhabitants have reacted by asserting their own identity. PMID:25807785

  4. Examination of postmortem retinal folds: A non-invasive study.

    PubMed

    Oshima, Toru; Yoshikawa, Hiroshi; Ohtani, Maki; Mimasaka, Sohtaro

    2015-02-01

    The postmortem retinal fold has been previously documented, but its mechanism of formation is not known. All previous studies of the fold involved invasive techniques and the postmortem ocular fundus has yet to be non-invasively examined. Our study used the non-invasive techniques of monocular indirect ophthalmoscopy and ocular echography to examine 79 postmortem eyes of 42 bodies. We examined whether the postmortem retinal fold was associated with postmortem time, position, and/or age. Age was significantly associated with postmortem retinal fold formation (Mann-Whitney U test, P = 0.013), which led us to examine the effect of posterior vitreous detachment (PVD) on retinal folds. The absence of a PVD was statistically associated with the presence of a retinal fold (Fisher's exact test, P < 0.0001). Interestingly, the presence of a PVD was also significantly correlated with retinal fold height (Mann-Whitney U test, P < 0.0001). Therefore, we hypothesized that retinal folds result from postmortem vitreoretinal traction caused by eyeball flaccidity. We also believe that the loss of retinochoroidal hydrostatic pressure plays a role. It is important that forensic pathologists not confuse a postmortem retinal fold with traumatic retinal detachment or perimacular retinal folds caused by child abuse. When child abuse is suspected, forensic pathologists should perform enucleation and a subsequent histological examination for confirmation. PMID:25623189

  5. N -methyl- N -nitrosourea-induced retinal degeneration in mice.

    PubMed

    Chen, Yuan-Yuan; Liu, Shi-Liang; Hu, Dan-Ping; Xing, Yi-Qiao; Shen, Yin

    2014-04-01

    Mouse retinal degeneration models have been investigated for many years in the hope of understanding the mechanism of photoreceptor cell death. N -methyl- N -nitrosourea (MNU) has been previously shown to induce outer retinal degeneration in mice. After MNU was intraperitoneally injected in C57/BL mice, we observed a gradual decrease in the outer nuclear layer (ONL) thickness associated with photoreceptor outer segment loss, bipolar cell dendritic retraction and reactive gliosis. Reactive gliosis was confirmed by increased GFAP protein levels. More serious damage to the central retina as opposed to the peripheral retina was found in the MNU-induced retinal degeneration model. Retinal ganglion cells (RGC) appear to be spared for at least two months after MNU treatment. Following retinal vessel labelling, we observed vascular complexes in the distal vessels, indicating retinal vessel damage. In the remnant retinal photoreceptor of the MNU-treated mouse, concentrated colouring nuclei were detected by electron microscopy, together with the loss of mitochondria and displaced remnant synaptic ribbons in the photoreceptor. We also observed decreased mitochondrial protein levels and increased amounts of nitrosylation/nitration in the photoreceptors. The mechanism of MNU-induced apoptosis may result from oxidative stress or the loss of retinal blood supply. MNU-induced mouse retinal degeneration in the outer retina is a useful animal model for photoreceptor degeneration diseases, such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP). PMID:24509257

  6. Clinical Features of Newly Diagnosed Cytomegalovirus Retinitis in Northern Thailand

    PubMed Central

    Ausayakhun, Somsanguan; Keenan, Jeremy D; Ausayakhun, Sakarin; Jirawison, Choeng; Khouri, Claire M; Skalet, Alison H; Heiden, David; Holland, Gary N; Margolis, Todd P

    2011-01-01

    Purpose To characterize the clinical manifestations of cytomegalovirus (CMV) retinitis in northern Thailand. Design Prospective, observational cross-sectional study. Methods We recorded characteristics of 52 consecutive patients newly diagnosed with CMV retinitis at a tertiary university-based medical center in northern Thailand. Indirect ophthalmoscopy by experienced ophthalmologists was supplemented with fundus photography to determine the proportion of eyes with various clinical features of CMV retinitis. Results Of the 52 patients with CMV retinitis, 55.8% were female. All were HIV-positive. The vast majority (90.4%) had started antiretroviral therapy. CMV retinitis was bilateral in 46.2% of patients. Bilateral visual acuity worse than 20/60 was observed in 23.1% of patients. Of 76 eyes with CMV retinitis, 61.8% had zone I disease and 21.6% had lesions involving the fovea. Lesions larger than 25% of the retinal area were observed in 57.5% of affected eyes. CMV retinitis lesions commonly had marked or severe border opacity (47.4% of eyes). Vitreous haze was often present (46.1% of eyes). Visual impairment was more common in eyes with larger retinitis lesions. Retinitis lesion size, used as a proxy for duration of disease, was associated with fulminant appearance (OR 1.24 [1.01 – 1.51]), and marked or severe border opacity (OR 1.36 [1.11 – 1.67]). Based on lesion size, retinitis preceded antiretroviral treatment in each patient. Conclusions Patients presenting to a tertiary medical center in northern Thailand have advanced CMV retinitis, possibly due to delayed diagnosis. Earlier screening and treatment of CMV retinitis may limit progression of disease and prevent visual impairment in this population. PMID:22265148

  7. Melanopsin-expressing intrinsically photosensitive retinal ganglion cells in retinal disease.

    PubMed

    Feigl, Beatrix; Zele, Andrew J

    2014-08-01

    Melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) are a class of photoreceptors with established roles in non-image-forming processes. Their contributions to image-forming vision may include the estimation of brightness. Animal models have been central for understanding the physiological mechanisms of ipRGC function and there is evidence of conservation of function across species. Intrinsically photosensitive retinal ganglion cells can be divided into five ganglion cell subtypes that show morphological and functional diversity. Research in humans has established that ipRGCs signal environmental irradiance to entrain the central body clock to the solar day for regulating circadian processes and sleep. In addition, ipRGCs mediate the pupil light reflex (PLR), making the PLR a readily accessible behavioral marker of ipRGC activity. Less is known about ipRGC function in retinal and optic nerve disease, with emerging research providing insight into their function in diabetes, retinitis pigmentosa, glaucoma, and hereditary optic neuropathy. We briefly review the anatomical distributions, projections, and basic physiological mechanisms of ipRGCs and their proposed and known functions in animals and humans with and without eye disease. We introduce a paradigm for differentiating inner and outer retinal inputs to the pupillary control pathway in retinal disease and apply this paradigm to patients with age-related macular degeneration (AMD). In these cases of patients with AMD, we provide the initial evidence that ipRGC function is altered and that the dysfunction is more pronounced in advanced disease. Our perspective is that with refined pupillometry paradigms, the PLR can be extended to AMD assessment as a tool for the measurement of inner and outer retinal dysfunction. PMID:24879087

  8. The role of retinal and extra-retinal photostimulation in reproductive activity in broiler breeder hens.

    PubMed

    Mobarkey, N; Avital, N; Heiblum, R; Rozenboim, I

    2010-05-01

    Photostimulation of retinal photoreceptors, which are sensitive to green light, appears to inhibit reproductive activity in birds, whereas photostimulation of extra-retinal photoreceptors, which are sensitive to red light, accelerates it. The objective of this study was to determine the effect of either retinal or extra-retinal photostimulation on reproductive activities of broiler breeder hens. At 23 wk of age, Cobb hens (N=135) were divided into 9 rooms with individual cages (n=15). At 24 wk of age, 3 rooms were photostimulated (14L:10D) with white light (Control, n=45). Six rooms had 2 parallel lighting systems, red (660 nm) and green (560 nm), which were both on during 6 out of 14 h of the light period. Then, in 3 of these rooms, the green light was turned off and hens were exposed to a total of 14 h of red light (Red, n=45), and in the other 3, the red light was turned off and green lighting continued for a total of 14 h (Green, n=45). The Green group had reduced egg production; reduced plasma concentrations of ovarian steroids; reduced luteinizing hormone (LH)-beta, vasoactive intestinal peptide (VIP), and prolactin mRNA expression; and greater retinal green opsin mRNA expression (P < or = 0.05). The Red group had greater egg production; greater gonadotropin-releasing hormone-I (GnRH-I) and red opsin gene expression in the hypothalamus; and lesser green opsin gene expression in the retina (P < or = 0.05). We suggest that selective photostimulation of extra-retinal photostimulation as opposed to retinal photostimulation is a key factor in the determination of successful reproduction of broiler breeder hens. PMID:20022445

  9. Inner retinal change in a novel rd1-FTL mouse model of retinal degeneration

    PubMed Central

    Greferath, Ursula; Anderson, Emily E.; Jobling, Andrew I.; Vessey, Kirstan A.; Martinez, Gemma; de Iongh, Robb U.; Kalloniatis, Michael; Fletcher, Erica L.

    2015-01-01

    While photoreceptor loss is the most devastating result of inherited retinal degenerations such as retinitis pigmentosa, inner retinal neurons also undergo significant alteration. Detailing these changes has become important as many vision restorative therapies target the remaining neurons. In this study, the rd1-Fos-Tau-LacZ (rd1-FTL) mouse model was used to explore inner retinal change at a late stage of retinal degeneration, after the loss of photoreceptor nuclei. The rd1-FTL model carries a mutation in the phosphodiesterase gene, Pde6b, and an axonally targeted transgenic beta galactosidase reporter system under the control of the c-fos promoter. Retinae of transgenic rd1-FTL mice and control FTL animals aged 2–12 months were processed for indirect fluorescence immunocytochemistry. At 2 months of age, a time when the majority of photoreceptor nuclei are lost, there was negligible c-fos reporter (FTL) expression, however, from 4 months, reporter expression was observed to increase within subpopulations of amacrine and ganglion cells within the central retina. These areas of inner retinal FTL expression coincided with regions that contained aberrant Müller cells. Specifically, these cells exhibited reduced glutamine synthetase and Kir4.1 immunolabelling, whilst showing evidence of proliferative gliosis (increased cyclinD1 and glial fibrillary acidic protein expression). These changes were limited to distinct regions where cone photoreceptor terminals were absent. Overall, these results highlight that distinct areas of the rd1-FTL central retina undergo significant glial alterations after cone photoreceptor loss. These areas coincide with up-regulation of the c-fos reporter in the inner retina, which may represent a change in neuronal function/plasticity. The rd1-FTL mouse is a useful model system to probe changes that occur in the inner retina at later stages of retinal degeneration. PMID:26283925

  10. Breakdown of blood. Retinal barrier in RCS rats with inherited retinal degeneration.

    PubMed

    Essner, E; Pino, R M; Griewski, R A

    1980-11-01

    A breakdown in the blood-retinal barrier to certain proteins is described in mutant RCS rats with inherited retinal degeneration. Intravenously injected microperoxidase and horseradish peroxidase are extravasated from the outer (but not inner) retinal capillaries of these rats, at approximately 11 weeks of age and older. The number of affected capillaries increases with the age of the animals and progression of the retinal dystrophy until virtually all capillaries in the outer retina become permeable to these tracers. In such capillaries, enzyme reaction product is demonstrable in a greater proportion of luminal vesicles and in the majority of abluminal vesicles. Reaction product is also localized in cytoplasmic vacuoles, the basal laminae of endothelial cells and pericytes, and the perivascular spaces. The increased permeability of outer retinal capillaries in RCS rats appears to be due to an increase in transendothelial vesicular transport of the probe molecules. There was no evidence that either tracer permeated the interendothelial junctions or entered the basal laminae by reflux from the perivascular spaces. It is suggested that factors originating from the degenerated photoreceptor cells may play a role in stimulating the vesicular transport observed in permeable capillaries. In contrast to these findings, the outer retinal capillaries of RCS rats were not permeable to hemoglobin, catalase, or ferritin, regardless of the age of the animal or the degree of retinal degeneration. Since the vesicles that form at the luminal front are covered by a diaphragm, it is possible that this structure prevents entry of these larger proteins into the endothelial vesicle, even in capillaries that are demonstrably permeable to the smaller tracers. PMID:7421123

  11. The Effects of Nepafenac and Amfenac on Retinal Angiogenesis

    PubMed Central

    Yanni, Susan E.; Clark, Monika L.; Yang, Rong; Bingaman, David P.; Penn, John S.

    2009-01-01

    Purpose Nepafenac is a potent NSAID that rapidly penetrates the eye following topical ocular administration. In the eye, nepafenac is converted to amfenac, which has unique time-dependent inhibitory properties for COX-1 and COX-2. The purpose of the present study was to investigate the ability of amfenac to inhibit discrete aspects of the angiogenic cascade in vitro, and to test the efficacy of amfenac and nepafenac in vivo, using the rat OIR model. Methods Müller cells were treated with amfenac, celecoxib (COX-2), or SC-560 (COX-1), and hypoxia-induced VEGF and PGE2 assessed. Endothelial cells were treated with amfenac, celecoxib, or SC-560, and VEGF-induced proliferation and tube formation assessed. Rat pups were subjected to OIR, received intravitreal injections of amfenac, celecoxib, or SC-560, and neovascularization (NV), prostanoid production, and VEGF assessed. Other OIR-exposed pups were treated with topical nepafenac, ketorolac, or diclofenac, and inhibition of NV assessed. Results Amfenac treatment failed to inhibit hypoxia-induced VEGF production. Amfenac treatment significantly inhibited VEGF-induced tube formation and proliferation by EC. Amfenac treatment significantly reduced retinal prostanoid production and NV in OIR. Nepafenac treatment significantly reduced retinal NV in OIR; ketorolac and diclofenac had no effect. Conclusions Nepafenac and amfenac inhibit OIR more effectively than the commercially available topical and injectable NSAIDs used in this study. Our data suggests there are COX-dependent and COX-independent mechanisms by which amfenac inhibits OIR. Because it is bioavailable to the posterior segment following topical delivery, nepafenac appears to be a promising advancement in the development of therapies for neovascular eye diseases. PMID:19897019

  12. Fire protection countermeasures for containment ventilation systems

    SciTech Connect

    Alvares, N.J.; Beason, D.G.; Bergman, W.; Ford, H.W.; Lipska, A.E.

    1980-01-01

    The goal of this project is to find countermeasures to protect HEPA filters in exit ventilation ducts from the heat and smoke generated by fire. Several methods for partially mitigating the smoke exposure to the HEPA filters were identified through testing and analysis. These independently involve controlling the fuel, controlling the fire, and intercepting the smoke aerosol prior to its sorption on the HEPA filter. Exit duct treatment of aerosols is not unusual in industrial applications and involves the use of scrubbers, prefilters, and inertial impaction, depending on the size, distribution, and concentration of the subject aerosol. However, when these unmodified techniques were applied to smoke aerosols from fires on materials, common to experimental laboratories of LLNL, it was found they offered minimal protection to the HEPA filters. Ultimately, a continuous, movable, high-efficiency prefilter using modified commercial equipment was designed. This technique is capable of protecting HEPA filters over the total duration of the test fires. The reason for success involved the modificaton of the prefiltration media. Commercially available filter media has a particle sorption efficiency that is inversely proportional to media strength. To achieve properties of both efficiency and strength, we laminated rolling filter media with the desired properties. It is not true that the use of rolling prefilters solely to protect HEPA filters from fire-generated smoke aerosols is cost effective in every type of containment system, especially if standard fire-protection systems are available in the space. But in areas of high fire risk, where the potential fuel load is large and ignition sources are plentiful, the complication of a rolling prefilter in exit ventilation ducts to protect HEPA filters from smoke aerosols is definitely justified.

  13. Boolean methods of optimization over independence systems

    SciTech Connect

    Hulme, B.L.

    1983-01-01

    This paper presents both a direct and an iterative method of solving the combinatorial optimization problem associated with any independence system. The methods use Boolean algebraic computations to produce solutions. In addition, the iterative method employs a version of the greedy algorithm both to compute upper bounds on the optimum value and to produce the additional circuits needed at every stage. The methods are extensions of those used to solve a problem of fire protection at nuclear reactor power plants.

  14. Mechanisms of retroaxonal barrage firing in hippocampal interneurons.

    PubMed

    Sheffield, Mark E J; Edgerton, Gabrielle B; Heuermann, Robert J; Deemyad, Tara; Mensh, Brett D; Spruston, Nelson

    2013-10-01

    We recently described a new form of neural integration and firing in a subset of interneurons, in which evoking hundreds of action potentials over tens of seconds to minutes produces a sudden barrage of action potentials lasting about a minute beyond the inciting stimulation. During this persistent firing, action potentials are generated in the distal axon and propagate retrogradely to the soma. To distinguish this from other forms of persistent firing, we refer to it here as 'retroaxonal barrage firing', or 'barrage firing' for short. Its induction is blocked by chemical inhibitors of gap junctions and curiously, stimulation of one interneuron in some cases triggers barrage firing in a nearby, unstimulated interneuron. Beyond these clues, the mechanisms of barrage firing are unknown. Here we report new results related to these mechanisms. Induction of barrage firing was blocked by lowering extracellular calcium, as long as normal action potential threshold was maintained, and it was inhibited by blocking L-type voltage-gated calcium channels. Despite its calcium dependence, barrage firing was not prevented by inhibiting chemical synaptic transmission. Furthermore, loading the stimulated/recorded interneuron with BAPTA did not block barrage firing, suggesting that the required calcium entry occurs in other cells. Finally, barrage firing was normal in mice with deletion of the primary gene for neuronal gap junctions (connexin36), suggesting that non-neuronal gap junctions may be involved. Together, these findings suggest that barrage firing is probably triggered by a multicellular mechanism involving calcium signalling and gap junctions, but operating independently of chemical synaptic transmission. PMID:23878372

  15. Smoke detection in low-G fires

    NASA Technical Reports Server (NTRS)

    Urban, David L.; Griffin, Devon W.; Gard, Melissa Y.; Hoy, Michael

    1995-01-01

    Fires in spacecraft are considered a credible risk. To respond to this risk, NASA flew fire detectors on Skylab and the Space Shuttle (STS) and included them in the design for International Space Station Alpha (ISSA). In previous missions (Mercury, Gemini and Apollo), the crew quarters were so cramped that it was not considered credible that the astronauts could fail to observe a fire. The Skylab nodule included approximately 20 UV fire detectors. The space shuttle has 9 ionization detectors in the mid deck and flight deck and Spacelab has six additional ionization detectors. The planned detectors for ISSA are laser-diode, forward-scattering, smoke or particulate detectors. Current plans for the ISSA call for two detectors in the open area of the module and detectors in racks that have both cooling air flow and electrical power. Due to the complete absence of data concerning the nature of particulate and radiant emission from low-g fires, all three of these detector systems were designed based upon 1-g test data. As planned mission durations and complexity increase and the volume of spacecraft increases, the need for and importance of effective, crew independent, fire detection grows significantly. This requires more knowledge concerning low-gravity fires and how they might be detected. To date, no combustion-generated particulate samples have been collected for well-developed microgravity flames. All of the extant data come from drop tower tests and therefore only correspond to the early stages of a fire. The fuel sources were restricted to laminar gas-jet diffusion flames and rapidly overheated wire insulation. These gas-jet drop tower tests indicate, through thermophoretic sampling, that soot primaries and aggregates (groups of primary particles) in micro-g may be significantly larger than those in normal-g (ng). This raises new scientific questions about soot processes as well as practical issues for particulate detection/alarm threshold levels used in on

  16. Fire science at LLNL: A review

    SciTech Connect

    Hasegawa, H.K.

    1990-03-01

    This fire sciences report from LLNL includes topics on: fire spread in trailer complexes, properties of welding blankets, validation of sprinkler systems, fire and smoke detectors, fire modeling, and other fire engineering and safety issues. (JEF)

  17. Intravitreal injection of forskolin, homotaurine, and L-carnosine affords neuroprotection to retinal ganglion cells following retinal ischemic injury

    PubMed Central

    Adornetto, Annagrazia; Cavaliere, Federica; Varano, Giuseppe Pasquale; Rusciano, Dario; Morrone, Luigi Antonio; Corasaniti, Maria Tiziana; Bagetta, Giacinto; Nucci, Carlo

    2015-01-01

    Purpose Retinal ganglion cell (RGC) death is the final event leading to visual impairment in glaucoma; therefore, identification of neuroprotective strategies able to slow down or prevent the process is one of the main challenges for glaucoma research. The purpose of this study was to evaluate the neuroprotective potential of RGC death induced by the in vivo transient increase in intraocular pressure (IOP) of a combined treatment with forskolin, homotaurine, and L-carnosine. Forskolin (7beta-acetoxy-8, 13-epoxy-1a, 6β, 9a-trihydroxy-labd-14-en-11-one) is an activator of adenylate cyclase that decreases IOP by reducing aqueous humor production and functions as a neuroprotector due to its neurotrophin-stimulating activity. Homotaurine is a natural aminosulfonate compound endowed with neuromodulatory effects, while the dipeptide L-carnosine is known for its antioxidant properties. Methods Retinal ischemia was induced in the right eye of adult male Wistar rats by acutely increasing the IOP. Forskolin, homotaurine, and L-carnosine were intravitreally injected and RGC survival evaluated following retrograde labeling with FluoroGold. Total and phosphorylated Akt and glycogen synthase kinase-3β (GSK-3β) protein levels, as well as calpain activity, were analyzed with western blot. Protein kinase A (PKA) was inhibited by intravitreal injection of H89. Results A synergic neuroprotective effect on RGC survival was observed following the combined treatment with forskolin, homotaurine, and L-carnosine compared to forskolin alone. The observed neuroprotection was associated with reduced calpain activity, upregulation of phosphoinositide 3-kinase (PI3K)/Akt pathway, and inhibition of GSK-3β but was independent from PKA activation and distinct from the hypotensive effects of forskolin. Conclusions A multidrug/multitarget approach, by interfering with several pathways involved in RGC degeneration, may be promising to achieve glaucoma neuroprotection. PMID:26167113

  18. Fires in Myanmar (2007)

    NASA Technical Reports Server (NTRS)

    2007-01-01

    In Southeast Asia, fires are common and widespread throughout the dry season, which roughly spans the northern hemisphere winter months. People set fires to clear crop stubble and brush and to prepare grazing land for a new flush of growth when the rainy season arrives. These intentional fires are too frequently accompanied by accidental fires that invade nearby forests and woodlands. The combination of fires produces a thick haze that alternately lingers and disperses, depending on the weather. This image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite shows fire activity on March 19, 2007, across eastern India, Myanmar, Thailand, Laos, and China. Places where MODIS detected actively burning fires are marked in red on the image. The darker green areas are generally more wooded areas or forests, while the paler green and tan areas are agricultural land. Smoke pools over low-lying areas of the hilly terrain in gray pockets. The green tops of rolling hills in Thailand emerge from a cloud of low-lying smoke. According to news reports from Thailand, the smoke blanket created air quality conditions that were considered unhealthy for all groups, and it prompted the Thai Air Force to undertake cloud-seeding attempts in an effort to cleanse the skies with rain. Commercial air traffic was halted due to poor visibility.

  19. Forest Fire Observation

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Conditions on the perimeter of a forest fire can be obtained by use of airborne remote sensing techniques demonstrated by Ames Research Center. An Ames U-2 high-altitude survey aircraft served as an aerial fire observation system. Equipped with two types of sensors, the U-2 produces real-time infrared images of fireground scenes. Information acquired by the U-2's scanners defines the fire boundary and aids fire management decisions by showing the size, shape and direction of burn and the locations of hot spots in the fire zone. U-2 sends sensor date in digital form to an antenna at Ames Research Center. There the data is computer processed into images which are overlaid on U.S. Geological Survey topographical maps of the fire area. Maps are then transmitted by telecopy machine directly to fire control center. Whole process takes less than 10 minutes and the U-2 can provide information for up to five hours. Ames antenna can pick up signals from the U-2 anywhere within a 300 mile radius from Ames.

  20. Modelling of fire count data: fire disaster risk in Ghana.

    PubMed

    Boadi, Caleb; Harvey, Simon K; Gyeke-Dako, Agyapomaa

    2015-01-01

    Stochastic dynamics involved in ecological count data require distribution fitting procedures to model and make informed judgments. The study provides empirical research, focused on the provision of an early warning system and a spatial graph that can detect societal fire risks. It offers an opportunity for communities, organizations, risk managers, actuaries and governments to be aware of, and understand fire risks, so that they will increase the direct tackling of the threats posed by fire. Statistical distribution fitting method that best helps identify the stochastic dynamics of fire count data is used. The aim is to provide a fire-prediction model and fire spatial graph for observed fire count data. An empirical probability distribution model is fitted to the fire count data and compared to the theoretical probability distribution of the stochastic process of fire count data. The distribution fitted to the fire frequency count data helps identify the class of models that are exhibited by the fire and provides time leading decisions. The research suggests that fire frequency and loss (fire fatalities) count data in Ghana are best modelled with a Negative Binomial Distribution. The spatial map of observed fire frequency and fatality measured over 5 years (2007-2011) offers in this study a first regional assessment of fire frequency and fire fatality in Ghana. PMID:26702383

  1. Alterations to retinal architecture prior to photoreceptor loss in a mouse model of retinitis pigmentosa.

    PubMed

    Roche, Sarah L; Wyse-Jackson, Alice C; Byrne, Ashleigh M; Ruiz-Lopez, Ana M; Cotter, Thomas G

    2016-01-01

    Mouse models of retinitis pigmentosa (RP) are essential tools in the pursuit to understand fully what cell types and processes underlie the degeneration observed in RP. Knowledge of these processes is required if we are to develop successful therapies to treat this currently incurable disease. We have used the rd10 mouse model of RP to study retinal morphology prior to photoreceptor loss, using immunohistochemistry and confocal microscopy on cryosections, since little is known about how the mutation affects the retina during this period. We report novel findings that the mutation in the rd10 mouse results in retinal abnormalities earlier than was previously thought. Defects in rod and cone outer segments, bipolar cells, amacrine cells and photoreceptor synapses were apparent in the retina during early stages of postnatal retinal development and prior to the loss of photoreceptors. Additionally, we observed a dramatic response of glial cells during this period. Microglia responded as early as postnatal day (P) 5; ?13 days before any photoreceptor loss is detected with Müller glia and astrocytes exhibiting changes from P10 and P15 respectively. Overall, these findings present pathological aspects to the postnatal development of the rd10 retina, contributing significantly to our understanding of disease onset and progression in the rd10 mouse and provide a valuable resource for the study of retinal dystrophies. PMID:27160072

  2. Multispectral retinal image analysis: a novel non-invasive tool for retinal imaging

    PubMed Central

    Calcagni, A; Gibson, J M; Styles, I B; Claridge, E; Orihuela-Espina, F

    2011-01-01

    Purpose To develop a non-invasive method for quantification of blood and pigment distributions across the posterior pole of the fundus from multispectral images using a computer-generated reflectance model of the fundus. Methods A computer model was developed to simulate light interaction with the fundus at different wavelengths. The distribution of macular pigment (MP) and retinal haemoglobins in the fundus was obtained by comparing the model predictions with multispectral image data at each pixel. Fundus images were acquired from 16 healthy subjects from various ethnic backgrounds and parametric maps showing the distribution of MP and of retinal haemoglobins throughout the posterior pole were computed. Results The relative distributions of MP and retinal haemoglobins in the subjects were successfully derived from multispectral images acquired at wavelengths 507, 525, 552, 585, 596, and 611 nm, providing certain conditions were met and eye movement between exposures was minimal. Recovery of other fundus pigments was not feasible and further development of the imaging technique and refinement of the software are necessary to understand the full potential of multispectral retinal image analysis. Conclusion The distributions of MP and retinal haemoglobins obtained in this preliminary investigation are in good agreement with published data on normal subjects. The ongoing development of the imaging system should allow for absolute parameter values to be computed. A further study will investigate subjects with known pathologies to determine the effectiveness of the method as a screening and diagnostic tool. PMID:21904394

  3. Retinal tears and rhegmatogenous retinal detachment after intravitreal injections: its prevalence and case reports

    PubMed Central

    Karabag, Revan Yildirim; Parlak, Melih; Cetin, Gölgem; Yaman, Aylin; Osman Saatci, A.

    2015-01-01

    Purpose To report the prevalence of postoperative retinal tear or rhegmatogenous retinal detachment secondary to intravitreal injections. Methods Surgical and medical records of patients who received intravitreal injections at the practice of a single retina specialist from January 2004 to May 2013 and who were followed for at least 6 months were investigated retrospectively. Results During the study period, a total of 3,907 intravitreal injections were performed in 1,049 eyes of 784 patients (416 males [47%]). The mean number of injections per eye was 3.72 ± 3.43 (range, 1–22). The mean age of the participants was 67.03 ± 13.56 (range, 5–94 years). The mean follow-up time was 31.98 ± 22.86 months (range, 6–144 months). Retinal break or rhegmatogenous retinal detachment occurred in 3 injections of 3 eyes, yielding an overall prevalence of 0.077% per injection and 0.29% per eye. Conclusions Retinal tear and rhegmatogenous detachment are rare complications of intravitreal injection. Precautions should be taken especially in patients having predisposing conditions, such as high myopia, or any other vitreoretinal disorders. PMID:27330458

  4. Transition of differential histone H3 methylation in photoreceptors and other retinal cells during retinal differentiation

    PubMed Central

    Ueno, Kazuko; Iwagawa, Toshiro; Kuribayashi, Hiroshi; Baba, Yukihiro; Nakauchi, Hiromitsu; Murakami, Akira; Nagasaki, Masao; Suzuki, Yutaka; Watanabe, Sumiko

    2016-01-01

    To analyze cell lineage-specific transitions in global transcriptional and epigenetic changes during retinogenesis, we purified retinal cells from normal mice during postnatal development into two fractions, namely, photoreceptors and other retinal cells, based on Cd73 expression, and performed RNA sequencing and ChIP sequencing of H3K27me3 and H3K4me3. Genes expressed in the photoreceptor lineage were marked with H3K4me3 in the Cd73-positive cell fraction; however, the level of H3K27me3 was very low in both Cd73-positive and -negative populations. H3K27me3 may be involved in spatio-temporal onset of a subset of bipolar-related genes. Subsets of genes expressed in amacrine and retinal ganglion cells, which are early-born retinal cell types, were suggested to be maintained in a silent state by H3K27me3 during late-stage retinogenesis. In the outer nuclear layer, upregulation of Rho and rod-related genes were observed in Ezh2-ablated retina, suggesting a role for H3K27me3 in the maintenance of proper expression levels. Taken together, our data on the transition of lineage-specific molecular signatures during development suggest that histone methylation is involved in retinal differentiation and maintenance through cell lineage-specific mechanisms. PMID:27377164

  5. Changes in morphology of retinal ganglion cells with eccentricity in retinal degeneration.

    PubMed

    Anderson, E E; Greferath, U; Fletcher, E L

    2016-05-01

    Ganglion cells are the output neurons of the retina and are known to remodel during the subtle plasticity changes that occur following the death of photoreceptors in inherited retinal degeneration. We examine the influence of retinal eccentricity on anatomical remodelling and ganglion cell morphology well after photoreceptor loss. Rd1 mice that have a mutation in the β subunit of phosphodiesterase 6 were used as a model of retinal degeneration and gross remodelling events were examined by processing serial sections for immunocytochemistry. Retinal wholemounts from rd1-Thy1 and control Thy1 mice that contained a fluorescent protein labelling a subset of ganglion cells were processed for immunohistochemistry at 11 months of age. Ganglion cells were classified based on their soma size, dendritic field size and dendritic branching pattern and their dendritic fields were analysed for their length, area and quantity of branching points. Overall, more remodelling was found in the central compared with the peripheral retina. In addition, the size and complexity of A2, B1, C1 and D type ganglion cells located in the central region of the retina decreased. We propose that the changes in ganglion cell morphology are correlated with remodelling events in these regions and impact the function of retinal circuitry in the degenerated retina. PMID:26670589

  6. Retinal area detector from scanning laser ophthalmoscope (SLO) images for diagnosing retinal diseases.

    PubMed

    Haleem, Muhammad Salman; Han, Liangxiu; van Hemert, Jano; Li, Baihua; Fleming, Alan

    2015-07-01

    Scanning laser ophthalmoscopes (SLOs) can be used for early detection of retinal diseases. With the advent of latest screening technology, the advantage of using SLO is its wide field of view, which can image a large part of the retina for better diagnosis of the retinal diseases. On the other hand, during the imaging process, artefacts such as eyelashes and eyelids are also imaged along with the retinal area. This brings a big challenge on how to exclude these artefacts. In this paper, we propose a novel approach to automatically extract out true retinal area from an SLO image based on image processing and machine learning approaches. To reduce the complexity of image processing tasks and provide a convenient primitive image pattern, we have grouped pixels into different regions based on the regional size and compactness, called superpixels. The framework then calculates image based features reflecting textural and structural information and classifies between retinal area and artefacts. The experimental evaluation results have shown good performance with an overall accuracy of 92%. PMID:25167560

  7. Transition of differential histone H3 methylation in photoreceptors and other retinal cells during retinal differentiation.

    PubMed

    Ueno, Kazuko; Iwagawa, Toshiro; Kuribayashi, Hiroshi; Baba, Yukihiro; Nakauchi, Hiromitsu; Murakami, Akira; Nagasaki, Masao; Suzuki, Yutaka; Watanabe, Sumiko

    2016-01-01

    To analyze cell lineage-specific transitions in global transcriptional and epigenetic changes during retinogenesis, we purified retinal cells from normal mice during postnatal development into two fractions, namely, photoreceptors and other retinal cells, based on Cd73 expression, and performed RNA sequencing and ChIP sequencing of H3K27me3 and H3K4me3. Genes expressed in the photoreceptor lineage were marked with H3K4me3 in the Cd73-positive cell fraction; however, the level of H3K27me3 was very low in both Cd73-positive and -negative populations. H3K27me3 may be involved in spatio-temporal onset of a subset of bipolar-related genes. Subsets of genes expressed in amacrine and retinal ganglion cells, which are early-born retinal cell types, were suggested to be maintained in a silent state by H3K27me3 during late-stage retinogenesis. In the outer nuclear layer, upregulation of Rho and rod-related genes were observed in Ezh2-ablated retina, suggesting a role for H3K27me3 in the maintenance of proper expression levels. Taken together, our data on the transition of lineage-specific molecular signatures during development suggest that histone methylation is involved in retinal differentiation and maintenance through cell lineage-specific mechanisms. PMID:27377164

  8. The effect of dendritic cells on the retinal cell transplantation

    SciTech Connect

    Oishi, Akio; Nagai, Takayuki; Mandai, Michiko Takahashi, Masayo; Yoshimura, Nagahisa

    2007-11-16

    The potential of bone marrow cell-derived immature dendritic cells (myeloid iDCs) in modulating the efficacy of retinal cell transplantation therapy was investigated. (1) In vitro, myeloid iDCs but not BMCs enhanced the survival and proliferation of embryonic retinal cells, and the expression of various neurotrophic factors by myeloid iDCs was confirmed with RT-PCR. (2) In subretinal transplantation, neonatal retinal cells co-transplanted with myeloid iDCs showed higher survival rate compared to those transplanted without myeloid iDCs. (3) CD8 T-cells reactive against donor retinal cells were significantly increased in the mice with transplantation of retinal cells alone. These results suggested the beneficial effects of the use of myeloid iDCs in retinal cell transplantation therapy.

  9. Contribution of Microglia-Mediated Neuroinflammation to Retinal Degenerative Diseases

    PubMed Central

    Madeira, Maria H.; Boia, Raquel; Santos, Paulo F.; Ambrósio, António F.; Santiago, Ana R.

    2015-01-01

    Retinal degenerative diseases are major causes of vision loss and blindness worldwide and are characterized by chronic and progressive neuronal loss. One common feature of retinal degenerative diseases and brain neurodegenerative diseases is chronic neuroinflammation. There is growing evidence that retinal microglia, as in the brain, become activated in the course of retinal degenerative diseases, having a pivotal role in the initiation and propagation of the neurodegenerative process. A better understanding of the events elicited and mediated by retinal microglia will contribute to the clarification of disease etiology and might open new avenues for potential therapeutic interventions. This review aims at giving an overview of the roles of microglia-mediated neuroinflammation in major retinal degenerative diseases like glaucoma, age-related macular degeneration, and diabetic retinopathy. PMID:25873768

  10. Adaptive Optics Technology for High-Resolution Retinal Imaging

    PubMed Central

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2013-01-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging. PMID:23271600

  11. Combined branch retinal vein and artery occlusion in toxoplasmosis.

    PubMed

    Aggio, Fabio Bom; Novelli, Fernando José de; Rosa, Evandro Luis; Nobrega, Mário Junqueira

    2016-01-01

    A 22-year-old man complained of low visual acuity and pain in his left eye for five days. His ophthalmological examination revealed 2+ anterior chamber reaction and a white, poorly defined retinal lesion at the proximal portion of the inferotemporal vascular arcade. There were retinal hemorrhages in the inferotemporal region extending to the retinal periphery. In addition, venous dilation, increased tortuosity, and ischemic retinal whitening along the inferotemporal vascular arcade were also observed. A proper systemic work-up was performed, and the patient was diagnosed with ocular toxoplasmosis. He was treated with an anti-toxoplasma medication, and his condition slowly improved. Inferior macular inner and middle retinal atrophy could be observed on optical coherence tomography as a sequela of ischemic injury. To our knowledge, this is the first report of combined retinal branch vein and artery occlusion in toxoplasmosis resulting in a striking and unusual macular appearance. PMID:27463632

  12. Cytomegalovirus Retinitis after Intravitreal Bevacizumab Injection in an Immunocompetent Patient

    PubMed Central

    Bae, So Hyun; Kim, Tae Wan; Chung, Hum

    2013-01-01

    We report a case of cytomegalovirus (CMV) retinitis after intravitreal bevacizumab injection. A 61-year-old woman with diabetic macular edema developed dense vitritis and necrotizing retinitis 3 weeks after intravitreal bevacizumab injection. A diagnostic vitrectomy was performed. The undiluted vitreous sample acquired by vitrectomy was analyzed by polymerase chain reaction and culture. Polymerase chain reaction of the vitreous was positive for CMV DNA. Other laboratory results did not show evidence of other infectious retinitis and systemic immune dysfunction. Human immunodeficiency virus antibodies were also negative. After systemic administration of ganciclovir, retinitis has resolved and there has been no recurrence of retinitis during the follow-up period of 12 months. Ophthalmologists should be aware of potential risk for CMV retinitis after intravitreal bevacizumab injection. PMID:23372384

  13. Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography

    PubMed Central

    Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K. W.; Yoshimura, Nagahisa

    2016-01-01

    Purpose To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. Methods The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Results Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. Conclusions The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction. PMID:26814541

  14. Relationship between Retinal Vascular Caliber and Coronary Artery Disease in Patients with Non-Alcoholic Fatty Liver Disease (NAFLD)

    PubMed Central

    Josef, Pikkel; Ali, Ibrahim; Ariel, Prober; Alon, Marmor; Nimer, Assy

    2013-01-01

    Objective: To evaluate the relationship between retinal vascular caliber and cardiovascular disease in non-alcoholic fatty liver disease (NAFLD) patients without diabetes and hypertension. Methods: Intention to treat study of individuals who underwent cardiac computed tomography (CT) during a two year period. Coronary artery disease (CAD) was defined as stenosis of >50% in at least one major coronary artery. Liver and spleen density were measured by abdominal (CT); intima-media thickness (IMT) by Doppler ultrasound; retinal artery and vein diameter by colored-retinal angiography; and metabolic syndrome by ATP III guidelines. Serum biomarkers of insulin resistance, inflammation, and oxidant-antioxidant status were assessed. Results: Compared with 22 gender and age matched controls, the 29 NAFLD patients showed higher prevalence of coronary plaques (70% vs. 30%, p < 0.001), higher prevalence of coronary stenosis (30% vs. 15%, p < 0.001), lower retinal arteriole-to-venule ratio (AVR) (0.66 ± 0.06 vs. 0.71 ± 0.02, p < 0.01), higher IMT (0.98 ± 0.3 vs. 0.83 ± 0.1, p < 0.04), higher carotid plaques (60% vs. 40%, p < 0.001), higher homeostasis model assessment of insulin resistance (HOMA) (4.0 ± 3.4 vs. 2.0 ± 1.0, p < 0.005), and higher triglyceride levels (200 ± 80 vs. 150 ± 60, p < 0.005) than controls. Multivariate analysis showed fatty liver (OR 2.5; p < 0.01), IMT (OR 2.3 p < 0.001), and retinal AVR ratio (OR 1.5, p < 0.01) to be strongly associated with CAD independent of metabolic syndrome (OR 1.2, p < 0.05). Conclusions: Patients with smaller retinal AVR (<0.7) are likely to be at increased risk for CAD and carotid atherosclerosis in patients with NAFLD even without hypertension or diabetes. PMID:23924883

  15. Electronic firing systems and methods for firing a device

    DOEpatents

    Frickey, Steven J.; Svoboda, John M.

    2012-04-24

    An electronic firing system comprising a control system, a charging system, an electrical energy storage device, a shock tube firing circuit, a shock tube connector, a blasting cap firing circuit, and a blasting cap connector. The control system controls the charging system, which charges the electrical energy storage device. The control system also controls the shock tube firing circuit and the blasting cap firing circuit. When desired, the control system signals the shock tube firing circuit or blasting cap firing circuit to electrically connect the electrical energy storage device to the shock tube connector or the blasting cap connector respectively.

  16. Independent Peer Reviews

    SciTech Connect

    2012-03-16

    Independent Assessments: DOE's Systems Integrator convenes independent technical reviews to gauge progress toward meeting specific technical targets and to provide technical information necessary for key decisions.

  17. Nanocarriers of nanotechnology in retinal diseases.

    PubMed

    Al-Halafi, Ali M

    2014-10-01

    We are approaching a new era of retinal pharmacotherapy where new drugs are rapidly being worked out for the treatment of posterior-segment disease. Recent development in ocular drug delivery systems research has provided new insights into drug development, and the use of nanoparticles for drug delivery is thus a promising excellent approach for advanced therapy of ocular diseases. The primary goal is to develop a variety of drug delivery systems to complement and further enhance the efficacy of the available new medications. The ideal sustained release technology will provide a high level of safety with continuous release over an extended period of time while maintaining almost total drug bioactivity. The use of nanocarriers, such as cyclodextrin nanoparticle suspension, liposomes, nanospheres and, nanoemulsions for gene therapy of retinal diseases has been highlighted in this review. PMID:25473348

  18. Retinal Image Simulation of Subjective Refraction Techniques.

    PubMed

    Perches, Sara; Collados, M Victoria; Ares, Jorge

    2016-01-01

    Refraction techniques make it possible to determine the most appropriate sphero-cylindrical lens prescription to achieve the best possible visual quality. Among these techniques, subjective refraction (i.e., patient's response-guided refraction) is the most commonly used approach. In this context, this paper's main goal is to present a simulation software that implements in a virtual manner various subjective-refraction techniques--including Jackson's Cross-Cylinder test (JCC)--relying all on the observation of computer-generated retinal images. This software has also been used to evaluate visual quality when the JCC test is performed in multifocal-contact-lens wearers. The results reveal this software's usefulness to simulate the retinal image quality that a particular visual compensation provides. Moreover, it can help to gain a deeper insight and to improve existing refraction techniques and it can be used for simulated training. PMID:26938648

  19. Biophotons Contribute to Retinal Dark Noise.

    PubMed

    Li, Zehua; Dai, Jiapei

    2016-06-01

    The discovery of dark noise in retinal photoreceptors resulted in a long-lasting controversy over its origin and the underlying mechanisms. Here, we used a novel ultra-weak biophoton imaging system (UBIS) to detect biophotonic activity (emission) under dark conditions in rat and bullfrog (Rana catesbeiana) retinas in vitro. We found a significant temperature-dependent increase in biophotonic activity that was completely blocked either by removing intracellular and extracellular Ca(2+) together or inhibiting phosphodiesterase 6. These findings suggest that the photon-like component of discrete dark noise may not be caused by a direct contribution of the thermal activation of rhodopsin, but rather by an indirect thermal induction of biophotonic activity, which then activates the retinal chromophore of rhodopsin. Therefore, this study suggests a possible solution regarding the thermal activation energy barrier for discrete dark noise, which has been debated for almost half a century. PMID:27059222

  20. Retinal Light Processing Using Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Loftus, David J. (Inventor); Leng, Theodore (Inventor); Fishman, Harvey (Inventor)

    2004-01-01

    Method and system for processing light signals received by the eye of a human or other animal, where the eye may be compromised or non-functioning. Incident light is received at first and second pixels in a photodetector array and provides a pixel electrical signal representing the received light. Each of an array of carbon nanotube (CNT) towers is connected to a pixel, has a first tower end penetrating a retinal active layer of the animal and has a second tower end positioned to receive to receive and transport the pixel electrical signal to the retinal active layer. The CNT tower may be coated with a biologically active substance or chemically modified to promote neurite connections with the tower. The photoreceptor array can be provide with a signal altering mechanism that alters at least one of light intensity and wavelength intensity sensed by a first pixel relative to a second pixel, to correct for one or more selected eye problems.