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physiology of vision

Matthew Osmond, Sarah M Bernier, Mina B Pantcheva, Melissa D Krebs
Glaucoma is a disease in which damage to the optic nerve leads to progressive, irreversible vision loss. The intraocular pressure (IOP) is the only modifiable risk factor for glaucoma and its lowering is considered a useful strategy for preventing or slowing down the progression of glaucomatous neuropathy. Elevated intraocular pressure associated with glaucoma is due to increased aqueous humor outflow resistance, primarily through the trabecular meshwork (TM) of the eye. Current in vitro models of the trabecular meshwork are oversimplified and do not capture the organized and complex three-dimensional nature of this tissue that consists primarily of collagen and glycoasaminoglycans...
October 24, 2016: Biotechnology and Bioengineering
Young Joon Kwon, Marni J Falk, Michael J Bennett
CLN3 disease (Spielmeyer-Vogt-Sjogren-Batten disease, previously known as classic juvenile neuronal ceroid lipofuscinosis, NCL) is a pediatric-onset progressive neurodegenerative disease characterized by progressive vision loss, seizures, loss of cognitive and motor function, and early death. While no precise biochemical mechanism or therapies are known, the pathogenesis of CLN3 disease involves intracellular calcium accumulation that may trigger apoptosis. Our prior work in in vitro cell models of CLN3 deficiency suggested that FDA-approved calcium channel antagonists may have therapeutic value...
October 20, 2016: Journal of Inherited Metabolic Disease
Vera Dinkelacker, Sophie Dupont, Séverine Samson
The new classification of epilepsy stratifies the disease into an acute level, based on seizures, and an overarching chronic level of epileptic syndromes (Berg et al., 2010). In this new approach, seizures are considered either to originate and evolve in unilateral networks or to rapidly encompass both hemispheres. This concept extends the former vision of focal and generalized epilepsies to a genuine pathology of underlying networks. These key aspects of the new classification can be linked to the concept of cognitive curtailing in focal epilepsy...
October 17, 2016: Epilepsy & Behavior: E&B
Chuanguang Yao, Hongxin Song, Ying Wan, Kefeng Ma, Chenyu Zheng, Hongda Cui, Peng Xin, Xubo Ji, Sheng-Yuan Deng
A porphyrin-based electro-photodynamic imaging system was fabricated for monitoring the concentration of oxygen. Distinct from the electrochemiluminescent (ECL) inability of numerous organic species in aqueous solutions, a strong and stable red irradiation at 634 nm could be stimulated electrochemically on zinc(II) meso-tetra(4-carboxyphenyl) porphine (ZnTCPP)/tetraoctylammonium bromide (TOAB) in the physiological condition. In terms of in situ electron paramagnetic resonance and ECL spectroscopies, the nature of ECL was thoroughly investigated, being exactly the chemiluminescence from singlet oxygen (1O2) produced during the successive electro-reduction of ZnTCPP...
October 20, 2016: ACS Applied Materials & Interfaces
Robert P Ellis, Mauricio A Urbina, Rod W Wilson
Exponentially rising CO2 (currently ~400 μatm) is driving climate change and causing acidification of both marine and freshwater environments. Physiologists have long known that CO2 directly affects acid-base and ion regulation, respiratory function and aerobic performance in aquatic animals. More recently, many studies have demonstrated that elevated CO2 projected for end of this century (e.g. 800-1000 μatm) can also impact physiology, and have substantial effects on behaviours linked to sensory stimuli (smell, hearing and vision) both having negative implications for fitness and survival...
October 20, 2016: Global Change Biology
George Taylor-Walker, Savannah A Lynn, Eloise Keeling, Rosie Munday, David A Johnston, Anton Page, Jennifer A Scott, Srini Goverdhan, Andrew J Lotery, J Arjuna Ratnayaka
Age-related Macular Degeneration (AMD) is a common, irreversible blinding condition that leads to the loss of central vision. AMD has a complex aetiology with both genetic as well as environmental risks factors, and share many similarities with Alzheimer's disease. Recent findings have contributed significantly to unravelling its genetic architecture that is yet to be matched by molecular insights. Studies are made more challenging by observations that aged and AMD retinas accumulate the highly pathogenic Alzheimer's-related Amyloid beta (Aβ) group of peptides, for which there appears to be no clear genetic basis...
October 14, 2016: Experimental Eye Research
Dierck Hillmann, Hendrik Spahr, Clara Pfäffle, Helge Sudkamp, Gesa Franke, Gereon Hüttmann
Noninvasive functional imaging of molecular and cellular processes of vision may have immense impact on research and clinical diagnostics. Although suitable intrinsic optical signals (IOSs) have been observed ex vivo and in immobilized animals in vivo, detecting IOSs of photoreceptor activity in living humans was cumbersome and time consuming. Here, we observed clear spatially and temporally resolved changes in the optical path length of the photoreceptor outer segment as a response to an optical stimulus in the living human eye...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
Olle Lind
Today, there is good knowledge of the physiological basis of bird colour vision and how mathematical models can be used to predict visual thresholds. However, we still know only little about how colour vision changes between different viewing conditions. This limits the understanding of how colour signalling is configured in habitats where the light of the illumination and the background may shift dramatically. I examined how colour discrimination in zebra finch (Taeniopygia guttata) is affected by adaptation to different backgrounds...
September 2016: Royal Society Open Science
Alexander M Dizhoor, Elena V Olshevskaya, Igor V Peshenko
Substitutions of Arg838 in dimerization domain of a human retinal membrane guanylyl cyclase 1 (RetGC1) linked to autosomal dominant cone-rod degeneration type 6 (CORD6) change RetGC1 regulation in vitro by Ca(2+) In addition to that, we find that R838S substitution makes RetGC1 less sensitive to inhibition by retinal degeneration-3 protein (RD3). We selectively expressed human R838S RetGC1 in mouse rods and documented decline in rod vision and rod survival. To verify that changes in rods were specifically caused by the CORD6 mutation, we used for the comparison cones, which in the same mice did not express R838S RetGC1 from the transgenic construct...
October 4, 2016: Journal of Biological Chemistry
Marc D de Smet, Jean Marie Stassen, Thijs C M Meenink, Tom Janssens, Valérie Vanheukelom, Gerrit J L Naus, Maarten J Beelen, Bart Jonckx
PURPOSE: Retinal vein occlusions (RVO) are a major cause of vision loss in people aged 50 years and older. Current therapeutic options limit the consequences of RVO but do not eliminate the cause. Cannulation of the involved vessel and removal of the clot may provide a more permanent solution with a less demanding follow-up. However, cannulation of smaller retinal veins remains challenging. This paper explores the use of ocriplasmin (recombinant plasmin without its kringles) to clear RVO, using a robotic micromanipulator...
September 28, 2016: British Journal of Ophthalmology
Evan J Myers, Aniko Marshall, Michael L Jennings, Mark D Parker
The SLC4A11 gene encodes the bicarbonate-transporter-related protein BTR1, which is mutated in syndromes characterized by vision and hearing loss. Signs of these diseases (congenital hereditary endothelial dystrophy (CHED) and Harboyan Syndrome) are evident in mouse models of Slc4a11 disruption. However, the intrinsic activity of Slc4a11 remains controversial, complicating assignment of its (patho)physiological role. Most studies concur that Slc4a11 transports H(+) (or the thermodynamically equivalent species OH(-)) rather than HCO3 (-) but disparities have arisen as to whether the transport is coupled to another species such as Na(+) or NH3/NH4 (+) Here for the first time, we examine the action of mouse Slc4a11 in Xenopus oocytes...
September 28, 2016: American Journal of Physiology. Cell Physiology
C A McNeill, S A Allan, P G Koehler, R M Pereira, E N I Weeks
Bed bugs as pests of public health importance recently experienced a resurgence in populations throughout the U.S. and other countries. Consequently, recent research efforts have focused on improving understanding of bed bug physiology and behaviour to improve management. While few studies have investigated the visual capabilities of bed bugs, the present study focused specifically on eye morphology and spectral sensitivity. A 3-D imaging technique was used to document bed bug eye morphology from the first instar through adult and revealed morphological characteristics that differentiate the common bed bug from the tropical bed bug as well as sex-specific differences...
September 27, 2016: Medical and Veterinary Entomology
Paloma T Gonzalez-Bellido, Samuel T Fabian, Karin Nordström
Motion vision provides important cues for many tasks. Flying insects, for example, may pursue small, fast moving targets for mating or feeding purposes, even when these are detected against self-generated optic flow. Since insects are small, with size-constrained eyes and brains, they have evolved to optimize their optical, neural and behavioral target visualization solutions. Indeed, even if evolutionarily distant insects display different pursuit strategies, target neuron physiology is strikingly similar...
September 20, 2016: Current Opinion in Neurobiology
Icilio Cavero, Henry Holzgrefe
INTRODUCTION: This report summarizes and comments key talks on the five traditional senses (ear, vestibular system, vision, taste, olfaction, and touch) which were delivered during the 2015 Annual Meeting of the Safety Pharmacology (SP) Society. AREAS COVERED: The functional observational battery (FOB) can detect major candidate drug liabilities only on ear, touch and vision. Anatomy, physiology, pharmacology, and pathology notions on each sensory system introduce speaker talks...
September 19, 2016: Journal of Pharmacological and Toxicological Methods
Dileep Kumar, Faraz Shafiq
Surviving sepsis guideline supports the placement of central venous cannulation (CVC) to target the deranged physiology. The placement of CVC is still challenging, which requires detailed knowledge of venous anatomy and orientation of congenital venous anomalies. Double or persistent left superior vena cava (PLSVC) is a common anomaly in thoracic venous system. Our patient had hidden PLSVC, though he was previously asymptomatic with no cardiac disease. We report the successful anaesthetic management of an adult male with septicaemia for emergency laparotomy...
September 2016: JPMA. the Journal of the Pakistan Medical Association
Shaheen Hasmat, Nigel H Lovell, Gregg J Suaning, Tsu-Hui Hubert Low, Jonathan Clark
The most devastating outcome of facial nerve paralysis is the inability to completely close the eye as it can lead to corneal ulceration and loss of vision. Gravity-assisted eye closure with upper lid loading is commonly used; however it is limited in replicating physiological eye closure to adequately lubricate the cornea. Superior results can be obtained using more advanced reconstructive approaches, however they depend on nerve regrowth which may be unpredictable and prolonged. This report describes a novel technique for creating an active eye closure using an implantable actuator...
September 7, 2016: Journal of Plastic, Reconstructive & Aesthetic Surgery: JPRAS
Paul J Donaldson, Angus C Grey, Bianca Maceo Heilman, Julie C Lim, Ehsan Vaghefi
The optical properties of the ocular lens are important to overall vision quality. As a transparent biological tissue, the lens contributes to the overall and dynamic focussing power of the eye, and corrects for optical errors introduced by the cornea. The optical properties of the lens change throughout life. Alterations to the refractive properties and transparency of the lens result in presbyopia and cataract, respectively. However, it is not well understood how changes to lens cellular structure and function initiate these changes in refraction and transparency...
September 14, 2016: Progress in Retinal and Eye Research
Andrea Martella, Rosa M Sepe, Cristoforo Silvestri, Jingjing Zang, Giulia Fasano, Oliana Carnevali, Paolo De Girolamo, Stephan C F Neuhauss, Paolo Sordino, Vincenzo Di Marzo
The developmental role of the endocannabinoid system still remains to be fully understood. Here, we report the presence of a complete endocannabinoid system during zebrafish development and show that the genes that code for enzymes that catalyze the anabolism and catabolism (mgll and dagla) of the endocannabinoid, 2-AG (2-arachidonoylglycerol), as well as 2-AG main receptor in the brain, cannabinoid receptor type 1, are coexpressed in defined regions of axonal growth. By using morpholino-induced transient knockdown of the zebrafish Daglα homolog and its pharmacologic rescue, we suggest that synthesis of 2-AG is implicated in the control of axon formation in the midbrain-hindbrain region and that animals that lack Daglα display abnormal physiological behaviors in tests that measure stereotyped movement and motion perception...
September 13, 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Paul L McNeil, Carolina Nebot, Alberto Cepeda, Katherine A Sloman
The development of the eye in vertebrates is dependent upon glucocorticoid signalling, however, specific components of the eye are sensitive to synthetic glucocorticoids. The presence of synthetic glucocorticoids within the aquatic environment may therefore have important consequences for fish, which are heavily reliant upon vision for mediating several key behaviours. The potential ethological impact of synthetic glucocorticoid oculotoxicity however has yet to be studied. Physiological and behavioural responses which are dependent upon vision were selected to investigate the possible toxicity of prednisolone, a commonly occurring synthetic glucocorticoid within the environment, during early life stages of zebrafish...
November 2016: Environmental Pollution
T U Krohne, J-P Allam, N Novak, F G Holz
BACKGROUND: Preoperative disinfection with povidone-iodine results in a significant reduction of the risk for postoperative endophthalmitis and secondary irreversible vision loss in intraocular surgeries and intravitreal injections. Nevertheless, this important measure is often omitted if so-called "iodine allergy" is suspected. We analyze the physiological and allergological basis for the construct of "iodine allergy". METHODS: This article is based on a selective literature review using the search term "allergy" in combination with "iodine", "povidone", "indocyanine green", or "seafood"...
September 6, 2016: Der Ophthalmologe: Zeitschrift der Deutschen Ophthalmologischen Gesellschaft
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