-
Indian Journal of Ophthalmology Jan 2019
Topics: Adult; Cysts; Diagnosis, Differential; Eye Diseases; Female; Humans; Vitreous Body
PubMed: 30574923
DOI: 10.4103/ijo.IJO_855_18 -
Journal of Visualized Experiments : JoVE Jan 2011The vitreous is an optically clear, collagenous extracellular matrix that fills the inside of the eye and overlies the retina. (1,2) Abnormal interactions between...
The vitreous is an optically clear, collagenous extracellular matrix that fills the inside of the eye and overlies the retina. (1,2) Abnormal interactions between vitreous substructures and the retina underlie several vitreoretinal diseases, including retinal tear and detachment, macular pucker, macular hole, age-related macular degeneration, vitreomacular traction, proliferative vitreoretinopathy, proliferative diabetic retinopathy, and inherited vitreoretinopathies. (1,2) The molecular composition of the vitreous substructures is not known. Since the vitreous body is transparent with limited surgical access, it has been difficult to study its substructures at the molecular level. We developed a method to separate and preserve these tissues for proteomic and biochemical analysis. The dissection technique in this experimental video shows how to isolate vitreous base, anterior hyaloid, vitreous core, and vitreous cortex from postmortem human eyes. One-dimensional SDS-PAGE analyses of each vitreous component showed that our dissection technique resulted in four unique protein profiles corresponding to each substructure of the human vitreous body. Identification of differentially compartmentalized proteins will reveal candidate molecules underlying various vitreoretinal diseases.
Topics: Dissection; Electrophoresis, Polyacrylamide Gel; Humans; Proteomics; Vitreous Body
PubMed: 21304469
DOI: 10.3791/2455 -
Biological & Pharmaceutical Bulletin Sep 2007The effect of poly-L-arginine with a molecular weight of 35.5 kDa (PLA) on the ocular absorption of hydrophilic molecules after instillation was examined in rabbits in...
The effect of poly-L-arginine with a molecular weight of 35.5 kDa (PLA) on the ocular absorption of hydrophilic molecules after instillation was examined in rabbits in vivo. FITC-labeled dextran (3.8 kDa, FD-4) and pyridoxamine were used as model hyprophilic molecules for absorption. The potential toxicity of PLA was evaluated by microscopic observation of the cornea, production of TNF-alpha, and the thickness of the corneal epithelia and stroma. The concentration of pyridoxamine and FD-4 in aqueous humor 30 min after a single instillation of a solution of PLA was 29- and 16-fold higher than that without PLA, respectively, but the drug concentrations were not determined in the vitreous body. Repetitive instillation of PLA every 30 min for 150 min achieved 31.1- and 13.3-fold increases in pyridoxamine and FD-4 in aqueous humor, respectively. Furthermore, significant amounts of pyridoxamine and FD-4 were detected in the vitreous body after the repetitive instillation of PLA, even although very little of these drugs was detected in the vitreous body in the control eye without PLA. On the other hand, repetitive instillation of PLA did not induce any alteration of corneal epithelial and stromal thickness, production of TNF-alpha, and disruption of the epithelial and stromal morphologies and neutrophil infiltration. Our findings suggest that PLA may be useful in promoting drug delivery of hydrophilic drugs to the ocular tissues without producing any significant corneal damage and inflammation.
Topics: Absorption; Animals; Aqueous Humor; Blotting, Western; Chromatography, High Pressure Liquid; Corneal Stroma; Epithelium, Corneal; Inflammation; Lipopolysaccharides; Male; Peptides; Pharmaceutical Preparations; Rabbits; Stimulation, Chemical; Tumor Necrosis Factor-alpha; Vitreous Body
PubMed: 17827737
DOI: 10.1248/bpb.30.1768 -
Transactions of the American... 2005Pharmacologic vitreolysis is a promising new therapy to improve vitreoretinal surgery and, ultimately, prevent disease by mitigating the contribution of vitreous to...
PURPOSE
Pharmacologic vitreolysis is a promising new therapy to improve vitreoretinal surgery and, ultimately, prevent disease by mitigating the contribution of vitreous to retinopathy. The mechanism of action of the agents being developed for pharmacologic vitreolysis remains unclear. The experiments in this thesis test the hypothesis that pharmacologic vitreolysis agents break down vitreous macromolecules into smaller particles.
METHODS
Microplasmin, hyaluronidase, and collagenase were tested in solutions of hyaluronan (n = 15) and collagen (n = 15), explants of bovine vitreous (n = 15), dissected porcine vitreous (n = 9), and intact porcine eyes (n = 18). There were also 21 controls, totaling 93 specimens. Vitreous macromolecule sizes were determined with dynamic light scattering (DLS), performed at intervals from 10 minutes to 24 hours following injections.
RESULTS
Studies of DLS reproducibility showed a coefficient of variance of less than 3.3% in all but one specimen. Microplasmin decreased porcine vitreous macromolecule size in a dose-dependent manner (correlation coefficient r = 0.93), with an 85% reduction after a 30-minute exposure to the maximum dose. Hyaluronidase decreased vitreous macromolecule size in hyaluronan solutions by 50% at high (1,000 IU/mL, P < .001) doses and in bovine vitreous by 20%. Collagenase decreased macromolecule size in collagen solutions by 20% at both low (1 mg/mL, P < .001) and high (10 mg/mL, P < .001) doses, but not at all in bovine vitreous.
CONCLUSIONS
Pharmacologic vitreolysis can induce a significant decrease in vitreous macromolecule sizes, depending upon the pharmacologic agents and the experimental model. Broad-spectrum agents were more effective than substrate-specific enzymes. Defining the molecular biology of pharmacologic vitreolysis has implications for surgical developments and may impact upon the design of clinical trials to induce prophylactic posterior vitreous detachment.
Topics: Animals; Cattle; Collagen; Collagenases; Dose-Response Relationship, Drug; Fibrinolysin; Hyaluronic Acid; Hyaluronoglucosaminidase; Light; Macromolecular Substances; Microscopy; Molecular Biology; Reproducibility of Results; Scattering, Radiation; Solutions; Swine; Time Factors; Vitreous Body
PubMed: 17057814
DOI: No ID Found -
Retina (Philadelphia, Pa.) Nov 2022To assess flow rates, nearfield effects, and traction of a dual-cutting 20,000 cpm vitrectomy probe (HYPERVIT, Alcon) versus a single-cutting 10,000 cpm probe (Advanced...
PURPOSE
To assess flow rates, nearfield effects, and traction of a dual-cutting 20,000 cpm vitrectomy probe (HYPERVIT, Alcon) versus a single-cutting 10,000 cpm probe (Advanced ULTRAVIT, Alcon).
METHODS
Flow rates were evaluated for 25+ and 27+ gauge probes using balanced salt solution or porcine cadaver vitreous (biased open, 50/50, and biased closed duty cycles). Probes were suspended in an open beaker, and flow rates were calculated using a precision balance. Nearfield effects and flow pulsatility were assessed using a validated simulation model based on experimental microparticle image velocimetry. Traction was assessed by attaching vitreous to a cantilever beam and measuring the deflection of the beam.
RESULTS
For HYPERVIT probes, aqueous flow rates were similar across all cutting rates. Vitreous flow rates increased with increasing cutting rates. At maximum cutting rates, aqueous flow was 62%-67% greater (25+) and 63% greater (27+) with HYPERVIT versus Advanced ULTRAVIT ( P < 0.05); vitreous flow was 44%-47% greater (25+) and 26%-32% greater (27+) with HYPERVIT versus Advanced ULTRAVIT ( P < 0.05). Nearfield effects were reduced, and peak traction forces were significantly lower for HYPERVIT versus Advanced ULTRAVIT ( P < 0.05).
CONCLUSION
Significantly greater aspiration flow, reduced nearfield effects, and reduced traction were observed with dual-action versus single-action probes.
Topics: Swine; Animals; Vitrectomy; Vitreous Body; Microsurgery; Sodium Chloride; Rheology; Water
PubMed: 35868025
DOI: 10.1097/IAE.0000000000003573 -
Frontiers in Endocrinology 2022We sought to reveal the expression profiles of transfer RNA-derived small RNAs (tsRNAs) and microRNAs (miRNAs) in the vitreous humor of patients with proliferative...
PURPOSE
We sought to reveal the expression profiles of transfer RNA-derived small RNAs (tsRNAs) and microRNAs (miRNAs) in the vitreous humor of patients with proliferative diabetic retinopathy (PDR).
METHODS
Vitreous humor samples were obtained from PDR patients and a control group for this study. Sequencing of small RNAs was conducted to assess the expression profiles of tsRNAs and miRNAs in both groups, which was followed by validation using reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR). Bioinformatics analyses were conducted to predict the target genes and their potential biological functions and signaling pathways.
RESULTS
A total of 37 tsRNAs and 70 miRNAs with significant differences were screened out from the vitreous humor samples of PDR patients compared to controls. Following validation by RT-qPCR, the target genes of the validated tsRNAs and miRNAs were predicted, and Gene Ontology analysis indicated that the target genes of the tsRNAs were most enriched in the cellular macromolecule metabolic process, cytoplasm, and ion-binding, while those of the miRNAs were most abundant in the regulation of major metabolic process, cytoplasm, and protein-binding. In addition, Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the target genes of said tsRNAs and miRNAs were most enriched in the adenosine monophosphate-activated protein kinase signaling pathway and Th17 cell differentiation, respectively.
CONCLUSIONS
The present study identified altered tsRNAs and miRNAs in vitreous humor samples of PDR patients, which may play important roles in the pathogenesis of PDR and could be considered potential therapeutic targets in the treatment of PDR.
Topics: Diabetes Mellitus; Diabetic Retinopathy; Gene Ontology; Humans; MicroRNAs; RNA, Transfer; Vitreous Body
PubMed: 35903272
DOI: 10.3389/fendo.2022.913370 -
Brazilian Journal of Medical and... Feb 2003Different from most mammalian species, the optic nerve of the rabbit eye is initially formed inside the retina where myelination of the axons of the ganglion cells...
Different from most mammalian species, the optic nerve of the rabbit eye is initially formed inside the retina where myelination of the axons of the ganglion cells starts and vascularization occurs. Astrocytes are confined to these regions. The aforementioned nerve fibers known as medullated nerve fibers form two bundles that may be identified with the naked eye. The blood vessels run on the inner surface of these nerve fiber bundles (epivascularization) and, accordingly, the accompanying astrocytes lie mostly facing the vitreous body from which they are separated only by the inner limiting membrane of the retina. The arrangement of the astrocytes around blood vessels leads to the formation of structures known as glial tufts. Fragments (N = 3) or whole pieces (N = 3) of the medullated nerve fiber region of three-month-old male rabbits (Orictolagus cuniculus) were fixed in glutaraldehyde followed by osmium tetroxide, and their thin sections were examined with a transmission electron microscope. Randomly located discontinuities (up to a few micrometers long) of the basement membrane of the inner limiting membrane of the retina were observed in the glial tufts. As a consequence, a direct contact between the astrocyte plasma membrane and vitreous elements was demonstrated, making possible functional interactions such as macromolecular exchanges between this glial cell type and the components of the vitreous body.
Topics: Animals; Astrocytes; Basement Membrane; Cell Communication; Male; Microscopy, Electron; Nerve Fibers; Rabbits; Retina; Vitreous Body
PubMed: 12563522
DOI: 10.1590/s0100-879x2003000200007 -
Translational Vision Science &... Mar 2022To study the dimensions and distribution of human vitreous collagen type II fragments collected after vitrectomy performed at varying cut rates and to evaluate if...
PURPOSE
To study the dimensions and distribution of human vitreous collagen type II fragments collected after vitrectomy performed at varying cut rates and to evaluate if increasing the cut rate produces smaller collagen fragments, thus reducing retinal traction and/or viscosity.
METHODS
Fluid was collected during core vitrectomies performed for macular surgery at cut rates from 1000 to 16,000 cuts per minute (CPM) and immediately refrigerated. Protein fractions were separated by molecular weight (MW; >100 kDa, 50-100 kDa, 50-30 kDa, 30-10 kDa, and <10 kDa) through centrifugal filters. The Human Collagen II ELISA Kit colorimetric assay was then used to measure the COL2A1 in unfiltered and filtered samples.
RESULTS
Vitreous samples collected after vitrectomy performed at 16,000 CPM contained a higher concentration of protein with MW over 100 kDa than at any other cutting frequency (P < 0.01). No significant differences were found in fractions collected with a MW between 50 and 100 kDa. Collagen type II fragments over 100 kDa were significantly more represented than smaller fragments at each cut rate. The proportion of smaller (50-100 kDa) collagen fragments compared with those over 100 kDa was higher at 2000 CPM than at higher cut rates.
CONCLUSIONS
Vitreous samples collected at different cut rates do not contain a significantly different proportion of collagen type II fragments of the tested MW. The extreme variability of vitreous flow through the cutter port may explain the uncertain predictability of collagen fragment MWs.
TRANSLATIONAL RELEVANCE
Increasing the cut rate does not produce vitreous fragments of proportionally smaller dimension. It is necessary to achieve an invariant instantaneous flow through the cutter port in order to decrease retinal traction during vitrectomy.
Topics: Collagen; Collagen Type II; Humans; Viscosity; Vitrectomy; Vitreous Body
PubMed: 35333285
DOI: 10.1167/tvst.11.3.29 -
Molecular Vision 2015The aim of this study was to evaluate the relationship between oxidative stress and human vitreous degeneration, using the presence of an evident posterior vitreous...
PURPOSE
The aim of this study was to evaluate the relationship between oxidative stress and human vitreous degeneration, using the presence of an evident posterior vitreous detachment (PVD) as a clinical sign and thiobarbituric acid-reactive substances (TBARS) and nitrite as oxidative biomarkers.
METHODS
We collected 42 vitreous samples from patients undergoing pars plana vitrectomy for two groups of vitreoretinal diseases (macular holes and epimacular membranes). TBARS and nitrite were assessed spectrophotometrically and compared to the presence of an evident PVD, considering other clinical features potentially related to the oxidative stress in the vitreous: diabetes, plasma fibrinogen, type of intraocular lens (IOL), and the vitreoretinal disease requiring the surgery.
RESULTS
Vitreous TBARS levels were significantly higher in patients with artificial IOLs compared to those with natural lenses and cataracts (1.39±0.64 versus 0.75±0.45; p=0.003). Furthermore, patients with PVD had a significant increase in vitreous TBARS compared to those without PVD (1.45±0.54 versus 0.53±0.38; p=0.001). The plasma fibrinogen levels explained 17% of the TBARS variance, with a significant correlation between these two markers (p=0.011). No significant differences were observed when nitrites were used as biomarkers.
CONCLUSIONS
Current IOLs, even with ultraviolet (UV) absorber, do not ensure the same photoprotection offered by natural lenses affected by corticonuclear cataracts. Furthermore, we observed a relevant correlation between the increased presence of peroxidation products in the vitreous and an evident PVD, but the nature of this relationship requires further study.
Topics: Aged; Aged, 80 and over; Biomarkers; Cataract; Cataract Extraction; Female; Fibrinogen; Humans; Lenses, Intraocular; Lipid Peroxidation; Male; Nitric Oxide; Nitrites; Retina; Retinal Perforations; Thiobarbituric Acid Reactive Substances; Vitrectomy; Vitreous Body; Vitreous Detachment
PubMed: 26396488
DOI: No ID Found -
Biophysical Journal Nov 2015The efficient treatment of many ocular diseases depends on the rapid diffusive distribution of solutes such as drugs or drug delivery vehicles through the vitreous...
The efficient treatment of many ocular diseases depends on the rapid diffusive distribution of solutes such as drugs or drug delivery vehicles through the vitreous humor. However, this multicomponent hydrogel possesses selective permeability properties, which allow for the diffusion of certain molecules and particles, whereas others are immobilized. In this study, we perform an interspecies comparison showing that the selective permeability properties of the vitreous are conserved across several mammalian species. We identify the polyanionic glycosaminoglycans hyaluronic acid and heparan sulfate as two key macromolecules that establish this selective permeability. We show that electrostatic interactions between the polyanionic macromolecules and diffusing solutes can be weakened by charge screening or enzymatic glycosaminoglycan digestion. Furthermore, molecule penetration into the vitreous is also charge-dependent and only efficient as long as the net charge of the molecule does not exceed a certain threshold.
Topics: Animals; Cattle; Diffusion; Heparitin Sulfate; Humans; Hyaluronic Acid; Permeability; Sheep; Swine; Vitreous Body
PubMed: 26588575
DOI: 10.1016/j.bpj.2015.10.002