Progressive visual loss and severe retinal degeneration in a captive Kodiak bear (Ursus arctos mittendorfi)

2020 ◽  
Vol 8 (3) ◽  
pp. e001115
Author(s):  
Kelly A Caruso ◽  
Seth Koch ◽  
Benjamin David Reynolds ◽  
Paul Massimo Giannoni McCarthy ◽  
Cameron J Whittaker
Keyword(s):  
Electrical Activity ◽  
Retinal Degeneration ◽  
General Anaesthesia ◽  
Outer Layer ◽  
Visual Loss ◽  
Ursus Arctos ◽  
Hepatic Neoplasm ◽  
Vascular Attenuation

A 27-year-old female Kodiak bear displayed signs of progressive visual loss over an 18-year period. The bear was examined under general anaesthesia, where fixed mydriatic pupils, a diffusely hyper-reflective retina with vascular attenuation was observed. An electroretinogram was performed bilaterally, revealing no electrical activity associated with either retina and confirming a diagnosis of severe bilateral retinal degeneration. The bear was euthanased eight months later due to a diagnosis of a metastasised hepatic neoplasm. Histopathology of the bear’s eyes revealed marked outer layer retinal degeneration. The aetiology of this retinal degeneration could not be confirmed.

scholarly journals Iron overload and iron chelating agent exposure in anemia-associated outer retinal degeneration: a case report and review of the literature

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mohamed Belmouhand ◽  
Christina Eckmann-Hansen ◽  
Tomas Ilginis ◽  
Eva Birgitte Leinøe ◽  
Bo Kok Mortensen ◽  
...  
Keyword(s):  
Case Report ◽  
Retinal Degeneration ◽  
Visual Loss ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Experimental Studies ◽  
Iron Chelation ◽  
Chelating Agent ◽  
Chronic Anemia ◽  
Slow Development

Abstract Background Deferoxamine retinopathy is the informally designated term used to describe a characteristic pattern of outer retinal degeneration in iron-overloaded chronic anemia patients who are treated with deferoxamine. We hypothesize that insufficiently treated iron overloading and not only deferoxamine is the cause of the retinal degeneration. Our case report is based on exposure histories of two anemia patients and literature review. Case presentation Both anemia patients presented with bilateral visual loss secondary to photoreceptor and retinal pigment epithelium degeneration. Chart review showed that visual loss came after a year-long slow, and rather monotonous rise in plasma ferritin concentrations, with no obvious relation to iron chelator exposure. In one patient, the onset of symptomatic visual loss came after a bout of fever followed by two additional febrile episodes, all accompanied by plasma ferritin spikes. Adjustment of iron chelation therapy did not improve visual function. Experimental studies clearly show that both systemic and intraocular exposure to iron ions can induce retinal degeneration. Conclusion The available evidence indicates that retinal degeneration in chronic anemia patients treated by deferoxamine is cause by insufficient iron chelation, not by deferoxamine. The actual role of iron chelating agents may be to promote a long enough survival to allow the slow development of retinal siderosis.

Novel method for the fabrication of ultrathin, free-standing and porous polymer membranes for retinal tissue engineering

2017 ◽  
Vol 5 (28) ◽  
pp. 5616-5622 ◽  
Author(s):  
Edgar Yong Sheng Tan ◽  
Shweta Agarwala ◽  
Yee Ling Yap ◽  
Colin Siang Hui Tan ◽  
Augustinus Laude ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Retinal Degeneration ◽  
Visual Loss ◽  
Polymer Membranes ◽  
Porous Polymer ◽  
Free Standing ◽  
Retinal Tissue ◽  
Novel Method

Retinal degeneration causes permanent visual loss and affects millions of people worldwide.

scholarly journals Complex hereditary spastic paraplegia associated with episodic visual loss caused by ACO2 variants

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Takenori Tozawa ◽  
Akira Nishimura ◽  
Tamaki Ueno ◽  
Akane Shikata ◽  
Yoshihiro Taura ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Hereditary Spastic Paraplegia ◽  
Visual Loss ◽  
Febrile Illness ◽  
Japanese Woman ◽  
Compound Heterozygous ◽  
Muscular Hypotonia ◽  
Spastic Paraplegia ◽  
Familial Cases ◽  
Old Japanese

AbstractMost patients with homozygous or compound heterozygous pathogenic ACO2 variants present with muscular hypotonia features, namely, infantile cerebellar-retinal degeneration. Recently, two studies reported rare familial cases of ACO2 variants presenting as complex hereditary spastic paraplegia (HSP) with broad clinical spectra. Here, we report the case of a 20-year-old Japanese woman with complex HSP caused by compound heterozygous ACO2 variants, revealing a new phenotype of episodic visual loss during febrile illness.

Measurement of spontaneous neuronal membrane activity by time lapse confocal microscopy

1995 ◽  
Vol 53 ◽  
pp. 972-973
Author(s):  
R H. Selinfreund ◽  
A. H. Cornell-Bell
Keyword(s):  
Membrane Potential ◽  
Confocal Microscopy ◽  
Patch Clamp ◽  
Electrical Activity ◽  
Time Lapse ◽  
Neuronal Firing ◽  
Neuronal Membrane ◽  
Pituitary Cells ◽  
Patch Clamp Recording ◽  
Spontaneous Electrical Activity

Cellular electrophysiological properties are normally monitored by standard patch clamp techniques . The combination of membrane potential dyes with time-lapse laser confocal microscopy provides a more direct, least destructive rapid method for monitoring changes in neuronal electrical activity. Using membrane potential dyes we found that spontaneous action potential firing can be detected using time-lapse confocal microscopy. Initially, patch clamp recording techniques were used to verify spontaneous electrical activity in GH4\C1 pituitary cells. It was found that serum depleted cells had reduced spontaneous electrical activity. Brief exposure to the serum derived growth factor, IGF-1, reconstituted electrical activity. We have examined the possibility of developing a rapid fluorescent assay to measure neuronal activity using membrane potential dyes. This neuronal regeneration assay has been adapted to run on a confocal microscope. Quantitative fluorescence is then used to measure a compounds ability to regenerate neuronal firing.The membrane potential dye di-8-ANEPPS was selected for these experiments. Di-8- ANEPPS is internalized slowly, has a high signal to noise ratio (40:1), has a linear fluorescent response to change in voltage.

Fate of sperm membrane in fertilized ova

1993 ◽  
Vol 51 ◽  
pp. 40-41
Author(s):  
Frank J. Longo
Keyword(s):  
Electron Microscopy ◽  
Electrical Activity ◽  
Sea Urchins ◽  
Morphological Changes ◽  
Integrated System ◽  
Electrophysiological Recording ◽  
Experimental Conditions ◽  
The Status ◽  
Sperm Membrane ◽  
Temporal And Spatial

Measurement of the egg's electrical activity, the fertilization potential or the activation current (in voltage clamped eggs), provides a means of detecting the earliest perceivable response of the egg to the fertilizing sperm. By using the electrical physiological record as a “real time” indicator of the instant of electrical continuity between the gametes, eggs can be inseminated with sperm at lower, more physiological densities, thereby assuring that only one sperm interacts with the egg. Integrating techniques of intracellular electrophysiological recording, video-imaging, and electron microscopy, we are able to identify the fertilizing sperm precisely and correlate the status of gamete organelles with the first indication (fertilization potential/activation current) of the egg's response to the attached sperm. Hence, this integrated system provides improved temporal and spatial resolution of morphological changes at the site of gamete interaction, under a variety of experimental conditions. Using these integrated techniques, we have investigated when sperm-egg plasma membrane fusion occurs in sea urchins with respect to the onset of the egg's change in electrical activity.

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