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Biomedicine & Pharmacotherapy =... Nov 2018Eye is the unique sense organ with complex and sophisticated anatomy and physiology. Being most instrumental for vision, it is secured by varied protective barriers;... (Review)
Review
Eye is the unique sense organ with complex and sophisticated anatomy and physiology. Being most instrumental for vision, it is secured by varied protective barriers; ranging from static (membranous) to dynamic (vascular) barrier. Although these barriers are very efficient to protect eye from exogenous substances and external stress, it is caught by various irreversible vision impairing ailments like cataract, conjunctivitis, glaucoma, uveitis, diabetic retinopathy (DR), diabetic macular edema (DME), age related macular degeneration (AMD), cytomegalovirus (CMV) retinitis, retinitis pigmentosa (RP), retinal vein occlusion (RVO), endophthalmitis affecting both anterior and posterior segment of eye. The treatment needed to reach the site of action is restricted by its characteristic barriers. The protective mechanism turns into hurdles when it comes to drug delivery especially in case of posterior segment of eye. Most common and preferable routes for ocular drug delivery are topical and systemic routes owing to their compliance and non-invasive nature, however they turned inefficient in delivering drugs to posterior segment. Currently, other local routes like intraocular and periocular (subconjunctival, subtenon, posterior juxtascleral, retrobulbar, peribulbar) are being explored and are showing positive outcomes in terms of symptomatic relief for a certain time period. But as these are invasive techniques, they also have some hidden long-term drawbacks on other side. Various advancements have been achieved till date in delivery of drug to posterior segment of eye, however despite these advancements; there is need of non-invasive or preferably less invasive technique considering prolonged treatments for such ailments. At times, dependency on invasive techniques may cause problems like patient incompliance, inflammation, contact cataract, retinal detachment, endophthalmitis etc. Here, in this review, barriers in ocular delivery, routes and recent advances in drug delivery to eye including patented commercial formulations with emphasis on posterior segment will be discussed.
Topics: Administration, Ophthalmic; Animals; Drug Delivery Systems; Drug Design; Eye; Eye Diseases; Humans; Pharmaceutical Preparations; Tissue Distribution
PubMed: 30257375
DOI: 10.1016/j.biopha.2018.08.138 -
Proceedings of the National Academy of... Feb 2022A hallmark of complex sensory systems is the organization of neurons into functionally meaningful maps, which allow for comparison and contrast of parallel inputs via...
A hallmark of complex sensory systems is the organization of neurons into functionally meaningful maps, which allow for comparison and contrast of parallel inputs via lateral inhibition. However, it is unclear whether such a map exists in olfaction. Here, we address this question by determining the organizing principle underlying the stereotyped pairing of olfactory receptor neurons (ORNs) in sensory hairs, wherein compartmentalized neurons inhibit each other via ephaptic coupling. Systematic behavioral assays reveal that most paired ORNs antagonistically regulate the same type of behavior. Such valence opponency is relevant in critical behavioral contexts including place preference, egg laying, and courtship. Odor-mixture experiments show that ephaptic inhibition provides a peripheral means for evaluating and shaping countervailing cues relayed to higher brain centers. Furthermore, computational modeling suggests that this organization likely contributes to processing ratio information in odor mixtures. This olfactory valence map may have evolved to swiftly process ethologically meaningful odor blends without involving costly synaptic computation.
Topics: Animals; Connectome; Drosophila Proteins; Drosophila melanogaster; Odorants; Olfactory Pathways; Olfactory Perception; Olfactory Receptor Neurons; Sense Organs; Smell
PubMed: 35091473
DOI: 10.1073/pnas.2120134119 -
International Ophthalmology Mar 2019The retina is continually exposed to free radicals from its rich blood supply, numerous mitochondria, and photons of light which strike its surface. Most pathological... (Review)
Review
PURPOSE
The retina is continually exposed to free radicals from its rich blood supply, numerous mitochondria, and photons of light which strike its surface. Most pathological processes that take place in the retina, such as inflammation, cell apoptosis, or angiogenesis, can hence involve free radicals directly or indirectly. Since inflammatory and oxidative stress pathways underlie retinal pathology, compounds that address these factors are therefore natural choices for treatment. This review article summarizes and provides commentary on curcumin's therapeutic potential use in ophthalmology with principal focus on retinal dosorders.
METHODS
Curcumin (diferuloylmethane) is a compound of the Indian spice turmeric (Curcuma longa) that has been found to be efficacious in preventing and treating a number of inflammatory diseases and neoplastic processes. Curcumin exerts anti-inflammatory, anti-tumor, antioxidant, and VEGF inhibition properties through modulation of numerous biochemical mediators. This makes curcumin particularly effective in retinal disorders.
RESULTS
Curcumin has found a role in slowing, and in some cases even reversing, age-related macular degeneration, diabetic retinopathy, retinitis pigmentosa, proliferative vitreoretinopathy, and retinal cancers.
CONCLUSIONS
However, studies on curcumin's efficacy have been limited mostly to animal studies. Moreover, the biomedical potential of curcumin is not easy to use, given its low solubility and oral bioavailability-more attention therefore has been given to nanoparticles and liposomes.
Topics: Anti-Inflammatory Agents, Non-Steroidal; Curcumin; Humans; Retina; Retinal Diseases; Treatment Outcome
PubMed: 29404861
DOI: 10.1007/s10792-018-0845-y -
Development Genes and Evolution Dec 2022Johnston's organ has been shown to act as an antennal auditory organ across a spectrum of insect species. In the hemimetabolous desert locust Schistocerca gregaria,...
Johnston's organ has been shown to act as an antennal auditory organ across a spectrum of insect species. In the hemimetabolous desert locust Schistocerca gregaria, Johnston's organ must be functional on hatching and so develops in the pedicellar segment of the antenna during embryogenesis. Here, we employ the epithelial cell marker Lachesin to identify the pedicellar domain of the early embryonic antenna and then triple-label against Lachesin, the mitosis marker phosphohistone-3, and neuron-specific horseradish peroxidase to reveal the sense-organ precursors for Johnston's organ and their lineages. Beginning with a single progenitor at approximately a third of embryogenesis, additional precursors subsequently appear in both the ventral and dorsal pedicellar domains, each generating a lineage or clone. Lineage locations are remarkably conserved across preparations and ages, consistent with the epithelium possessing an underlying topographic coordinate system that determines the cellular organization of Johnston's organ. By mid-embryogenesis, twelve lineages are arranged circumferentially in the pedicel as in the adult structure. Each sense-organ precursor is associated with a smaller mitotically active cell from which the neuronal complement of each clone may derive. Neuron numbers within a clone increase in discrete steps with age and are invariant between clones and across preparations of a given age. At mid-embryogenesis, each clone comprises five cells consolidated into a tightly bound cartridge. A long scolopale extends apically from each cartridge to an insertion point in the epithelium, and bundled axons project basally toward the brain. Comparative data suggest mechanisms that might also regulate the developmental program of Johnston's organ in the locust.
Topics: Animals; Sense Organs; Neurons; Grasshoppers; Embryonic Development
PubMed: 36138225
DOI: 10.1007/s00427-022-00695-2 -
Developmental Biology Nov 2017
Topics: Biological Evolution; Evolution, Molecular; Organogenesis; Sense Organs; Sensory Receptor Cells; Somatosensory Cortex
PubMed: 28889956
DOI: 10.1016/j.ydbio.2017.09.007 -
Clinical & Experimental Optometry Nov 2020Myopia, and especially high myopia, is associated with a number of posterior segment changes that are considered to be mostly a consequence of the increased axial... (Review)
Review
Myopia, and especially high myopia, is associated with a number of posterior segment changes that are considered to be mostly a consequence of the increased axial elongation. This can result in mechanical strain, attendant vascular changes, stretching and thinning of tissues, and atrophy/deformation of tissues in later or more advanced stages. Such myopia-related changes are observed as changes and/or abnormalities in the vitreous, choroid, retina and peripheral retina, sclera and/or optic disc. Although many of these changes are benign, at times they may be associated with significant vision impairment that either requires active intervention or may suggest future progression of the disease. This review systematically addresses the posterior segment conditions seen in myopic eyes, describes the features associated with the condition and details management pathways.
Topics: Choroid; Humans; Myopia; Optic Disk; Retina; Sclera
PubMed: 32227385
DOI: 10.1111/cxo.13060 -
Journal of Neurogenetics 2020From Sydney Brenner's backyard to hundreds of labs across the globe, inspiring six Nobel Prize winners along the way, research has come far in the past half century.... (Review)
Review
From Sydney Brenner's backyard to hundreds of labs across the globe, inspiring six Nobel Prize winners along the way, research has come far in the past half century. The journey is not over. The virtues of research are numerous and have been recounted extensively. Here, we focus on the remarkable progress made in sensory neurobiology research in . This nematode continues to amaze researchers as we are still adding new discoveries to the already rich repertoire of sensory capabilities of this deceptively simple animal. Worms possess the sense of taste, smell, touch, light, temperature and proprioception, each of which is being studied in genetic, molecular, cellular and systems-level detail. This impressive organism can even detect less commonly recognized sensory cues such as magnetic fields and humidity.
Topics: Animals; Behavior, Animal; Caenorhabditis elegans; Interneurons; Models, Animal; Neurobiology; Sensation; Sense Organs; Sensory Receptor Cells
PubMed: 33191820
DOI: 10.1080/01677063.2020.1823386 -
International Ophthalmology Jun 2022Hereditary haemorrhagic telangiectasia (HHT) or Osler-Rendu-Weber syndrome is a rare autosomal dominant disease, characterised by systemic angiodysplasia. Dysfunction of... (Review)
Review
Hereditary haemorrhagic telangiectasia (HHT) or Osler-Rendu-Weber syndrome is a rare autosomal dominant disease, characterised by systemic angiodysplasia. Dysfunction of the signalling pathway of β transforming growth factor is the main cause of HHT principally owing to mutations of the genes encoding for endoglin (ENG) and activin A receptor type II-like 1 (ACVRL1). Clinical manifestations can range from mucocutaneous telangiectasia to organ arterio-venous malformations and recurrent epistaxis. The early clinical manifestations may sometimes be subtle, and diagnosis may be delayed. The main ophthalmic manifestations historically reported in HHT are haemorrhagic epiphora, and conjunctival telangiectasia present in 45-65% of cases, however, imaging with wide-field fluorescein angiography has recently shown peripheral retinal telangiectasia in 83% of patients. Optimal management of HHT requires both understanding of the clinical presentations and detection of early signs of disease. Advances in imaging methods in ophthalmology such as wide-field fluorescein angiography, spectral domain optical coherence tomography, and near infrared reflectance promise further insight into the ophthalmic signs of HHT towards improved diagnosis and early management of possible severe complications.
Topics: Activin Receptors, Type II; Endoglin; Eye; Eye Diseases; Humans; Mutation; Telangiectasia, Hereditary Hemorrhagic
PubMed: 35034241
DOI: 10.1007/s10792-021-02197-y -
Nature Communications Nov 2020Hearing is a crucial sense in underwater environments for communication, hunting, attracting mates, and detecting predators. However, the tools currently used to study...
Hearing is a crucial sense in underwater environments for communication, hunting, attracting mates, and detecting predators. However, the tools currently used to study hearing are limited, as they cannot controllably stimulate specific parts of the auditory system. To date, the contributions of hearing organs have been identified through lesion experiments that inactivate an organ, making it difficult to gauge the specific stimuli to which each organ is sensitive, or the ways in which inputs from multiple organs are combined during perception. Here, we introduce Bio-Opto-Acoustic (BOA) stimulation, using optical forces to generate localized vibrations in vivo, and demonstrate stimulation of the auditory system of zebrafish larvae with precise control. We use a rapidly oscillated optical trap to generate vibrations in individual otolith organs that are perceived as sound, while adjacent otoliths are either left unstimulated or similarly stimulated with a second optical laser trap. The resulting brain-wide neural activity is characterized using fluorescent calcium indicators, thus linking each otolith organ to its individual neuronal network in a way that would be impossible using traditional sound delivery methods. The results reveal integration and cooperation of the utricular and saccular otoliths, which were previously described as having separate biological functions, during hearing.
Topics: Acoustic Stimulation; Acoustics; Animals; Brain; Hearing; Larva; Neurons; Otolithic Membrane; Sound; Vibration; Zebrafish
PubMed: 33257652
DOI: 10.1038/s41467-020-19982-5 -
Computerized Medical Imaging and... Jan 2021Multispectral imaging (MSI) of the ocular fundus provides a sequence of narrow-band images to show the different depths in the retina and choroid. One challenge in...
Multispectral imaging (MSI) of the ocular fundus provides a sequence of narrow-band images to show the different depths in the retina and choroid. One challenge in analyzing MSI images comes from the image-to-image spatial misalignment, which occurs because the acquisition time of eye MSI images is commonly longer than the natural time scale of the eye's saccadic movement. It is necessary to align images because ophthalmologists usually overlay two of the images to analyze specific features when analyzing MSI images. In this paper, we propose a weakly supervised MSI image registration network, called MSI-R-NET, for multispectral fundus image registration. Compared to other deep-learning-based registration methods, MSI-R-NET utilizes the blood vessel segmentation label to provide spatial correspondence. In addition, we employ a feature equilibrium module to connect the aggregating layers better, and propose a multiresolution auto-context structure to adapt the registration task. In the testing stage, given a new pair of MSI images, the trained model can predict the pixelwise spatial correspondence without labeled blood vessel information. The experimental results demonstrate that the proposed segmentation-driven registration method is highly accurate.
Topics: Choroid; Fundus Oculi; Image Processing, Computer-Assisted; Retina
PubMed: 33418174
DOI: 10.1016/j.compmedimag.2020.101815