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Biochemical Markers in Ophthalmology
Published in Ching-Yu Cheng, Tien Yin Wong, Ophthalmic Epidemiology, 2022
Abdus Samad Ansari, Pirro G. Hysi
Disease-associated genes often share basic functional properties, whose study can inform about disease mechanisms. There are many functional gene sets that are statistically enriched among the GWAS-identified POAG genes. One very enriched set of functional properties among POAG-associated genes is the cell cycle, cell division, inhibition, and apoptosis [53, 63]. These genes tend to be associated with endophenotypes underlying optic disc morphology features, such as VCDR, disc and rim areas. This seems to suggest that retinal ganglion cell vitality may be a mechanism leading to glaucoma. The presence of such a strong link between cell division inhibition and POAG points to potentially new and transformative pharmacological POAG treatments that will aim to boost cells’ regenerative capabilities and resilience. This is interesting, as to date there is only one available therapeutical option with neuroprotective properties (brimonidine). Experimental intervention aimed at inhibiting cyclin-dependent kinases, a protein family, which also included the CDKN2B protein, whose production and activity are under strong genetic regulation in POAG, have shown neuroprotection and improved clinical outcomes [64, 65]. Extending these studies to human glaucoma patients may lead to the development of novel treatments against the disease.
Comparative Anatomy and Physiology of the Mammalian Eye
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The inner plexiform layer is formed by the axons of the bipolar and amacrine cells and the dendrites of the ganglion cells.4 The ganglion cells form a single layer over most of the retina, the exception being adjacent to the fovea in those species in which this is present. The axons of the ganglion cells are aggregated into nerve fiber bundles which make up the nerve fiber layer. These bundles travel parallel to the retinal surface through arcades formed by the foot processes of the Muller cells.4 These are nonmyelinated nerve fibers until they reach the optic nerve where they acquire myelination. Depending on the species and where the myelination begins, it may be evident clinically. The innermost layer of the retina is the internal limiting membrane. This is a thick basement membrane that is smooth on its internal surface, but conforms to the uneven Muller cell basal plasma membrane externally.4
An Introduction to Consciousness and the Brain
Published in Max R. Bennett, The Idea of Consciousness, 2020
Ten years ago my colleague Bogdan Dreher and I set out to see if what Levi-Montalcini had discovered for the peripheral nervous system (namely that autonomic neurons could be induced to survive if provided with the material from their normal targets such as cardiac muscle or smooth muscle) might also apply for neurons in the central nervous system. We first showed that retinal ganglion cell neurons, the nerve cells in the retina that send visual information from it to the brain along the optic nerve (depicted in Figure 1.9), normally die during development. Furthermore, these retinal ganglion cells could be induced to survive when provided with a nutrient neurotrophic molecule from their targets in the brain. Those parts of the brain are called the superior colliculus and the lateral geniculate nucleus. The neurons survived and sprouted nerve processes profusely in a tissue culture plate if provided with the neurotrophic factor, just as Levi-Montalcini had described for autonomic neurons. The difference was that in this case, the retinal neurons were supplied with a factor from the brain and not from muscle. This was probably the first indication that neurotrophic growth factors exist in the brain and not just in the peripheral nervous system, and that these growth factors can allow for the survival and profuse axon spouting of a central neuron such as a retinal ganglion neuron.
microRNA-26a-5p Prevents Retinal Neuronal Cell Death in Diabetic Mice by Targeting PTEN
Published in Current Eye Research, 2022
Rui Shi, Dan-Dan Liu, Ying Cao, Yu-Shun Xue
Retinal ganglion cells are retinal neurons that are affected by many ocular neurodegenerative diseases. We then used TEM to observe the ultrastructure of the retinal ganglion cells to further identify the early pathological changes of the retina. These results reveal that the number and size of mitochondria were significantly decreased in the ganglions of diabetic mice receiving mimic control injection (Figure 4c and d) compared with the healthy controls (Figure 4a and b), although the morphology of ganglion cells appeared normal. Margination of chromatin and crenated nuclei of cells in the ganglion cell layer was also detected in the retina of diabetic mice. However, in mice injected with miR-26a, the mitochondria, chromatin, and nuclei structures were ameliorated (Figure 4e and f).
Blue light emission spectra of popular mobile devices: The extent of user protection against melatonin suppression by built-in screen technology and light filtering software systems
Published in Chronobiology International, 2020
Jorge a Calvo-Sanz, Carlos E Tapia-Ayuga
The intrinsically photosensible retinal ganglion cells (ipRGCs) are another type of photosensitive cells that are not involved in the visual process (Zhao et al. 2014). Those cells are directly involved with the suppression or activation of the secretion of melatonin, a neurohormone produced in the pineal gland involved in the regulation of circadian rhythms and with antidepressant and intraocular pressure regulatory, among other, actions (Carracedo et al. 2017). Melatonin synthesis is controlled with the help of these ipRGCs and is inhibited by evening and overnight light exposure. The melatonin suppression action spectrum (MSAS) has been previously defined (Aube et al. 2013); maximum melatonin suppression is induced by light of 446 nm, in the blue light spectrum. The interaction of artificial light, its spectrum of emission, and melatonin suppression have been widely described (Aube et al. 2013; Chellappa et al. 2011; Davis et al. 2015; Gooley et al. 2011; Hanifin et al. 2006; Rosiak and Zawilska 2005; Zawilska et al. 1999; Zhao et al. 2014).
Localization of melatonin and its receptors (melatonin 1a and 1b receptors) in the mouse inner ear
Published in Acta Oto-Laryngologica, 2019
In the mouse cochlea, stria vascularis showed a moderate fluorescent reaction to melatonin, melatonin receptor 1a (MT1a) and melatonin receptor 1b (MT1b), while the spiral prominence and spiral ligament showed faint fluorescence to MT1a, weak fluorescence to MT1b and no fluorescence to melatonin (Figure 1). In the organ of Corti, an intense fluorescent reaction to melatonin, moderate fluorescence to MT1a and MT1b were observed in both the outer hair cells (OHCs) and inner hair cells (IHCs). Immunoreactivity to melatonin, MT1a and MT1b was also observed in outer and inner pillar cells (Figure 1). Spiral ganglion cells showed moderate to strong immunoreactivity in the cytoplasm with granular appearance. Some cells showed more intensely stained background cytoplasm. The nerve fibers also showed a moderate fluorescent reaction to melatonin, MT1a and MT1b (Figure 1).