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A new look at vitreous-humour collagen.

ABSTRACT: The collagens of bovine vitreous-humour and nasal-septum cartilage have been extracted, fractionated and compared. Both tissues show the same heterogeneity of collagen types, consisting of type II, 1 alpha, 2 alpha, 3 alpha and C-PS collagens. The type II collagen of the vitreous humour was significantly more hydroxylated both in the lysine and proline residues than was that of cartilage. C-PS1 collagen, together with higher-Mr forms were present in the vitreous humour, but the higher-Mr forms were not seen in cartilage. Both C-PS1 and C-PS2 were present in vitreous humour and cartilage, but vitreous humour contained three times more of these collagens than did cartilage. Despite the difference in amount, the molar ratio C-PS1/C-PS2 was approx. 1 in both tissues, suggesting that they are components of a larger molecule. The 1 alpha, 2 alpha, 3 alpha collagens were present in the same concentration in both tissues. These three chains co-precipitated on dialysis against phosphate-buffered saline, pH 7.2, in a manner analogous to type V collagen.

SUBMITTER: Ayad S

PROVIDER: S-EPMC1153412 | biostudies-other | 1984 Mar

REPOSITORIES: biostudies-other

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The chemical composition of bovine vitreous-humour collagen fibres.

Project description:The insoluble protein fraction was prepared from the central and posterior peripheral fraction of bovine vitreous humour. The collagen present in this fraction was solubilized by pepsin and fractionated by gel chromatography. Analysis of the solubilized collagen fractions showed that the alpha-chain component had an amino acid composition and yielded a series of CNBr-cleavage peptides that showed it was very similar to type II collagen obtained from articular cartilage. Bovine vitreous-humour collagen alpha-chains differed, however, from those of cartilage collagen in that they had a lower alanine content and differed in their susceptibility to cleavage by CNBr. Satisfactory cleavage was obtained after two CNBr treatments involving reduction and alkylation. In addition, significant quantities of other peptides constituents were present in the vitreous-humour collagen fractions, and the galactose and glucose content of the alpha-chain fraction was more than double that of the same fraction obtained from articular cartilage. Although the origin of the additional peptide constituents in the vitreous-humour collagen preparations is not known, the results obtained indicate that they are probably not derived from a distinct type of alpha-chain component but may be terminal peptides covalently linked to the alpha 1 type-II helical portions of the collagen. The differences in the chemical composition of the vitreous-humour collagen indicate that vitreous-humour fibres are composed of a special type-II collagen.

| S-EPMC1161430 | biostudies-other

In vitro fibrillogenesis of collagen II from pig vitreous humour.

Project description:Collagen from pig vitreous humour was fractionated into a soluble and an insoluble fraction by centrifugation. Most of the collagen II in the soluble fraction was present as pN-collagen II (procollagen II without the C-terminal propeptide), besides smaller quantities of procollagen II, collagen II and two as yet unidentified alpha-chains of collagen II. Other collagen types may be present only in trace amounts. Collagen II of the insoluble fraction, which is mostly deposited in fibrillar aggregates, consists of both pN-collagen II and collagen II. To determine the possible role of collagen II precursors in the formation of the extracellular matrix of the vitreous humour these collagen molecules were purified and in vitro fibrillogenesis was used to demonstrate that pN-collagen II could form fibrils in mixtures with collagen II. These fibrils have a reduced mass per unit length depending on the content of pN-collagen in the mixture. Cross-sections of the newly formed fibrillar aggregates revealed a flattened shape. The incomplete processing of the precursors of collagen II may be part of regulatory mechanisms possibly controlling the formation of a translucent scaffold as is required in the vitreous humour.

| S-EPMC1136601 | biostudies-other

MicroRNA signatures in vitreous humour and plasma of patients with exudative AMD.

Project description:Age-related macular degeneration (AMD) is a leading cause of blindness worldwide affecting individuals over the age of 50. The neovascular form (NV AMD) is characterized by choroidal neovascularization (CNV) and responsible for the majority of central vision impairment. Using non-biased microRNA arrays and individual TaqMan qPCRs, we profiled miRNAs in the vitreous humour and plasma of patients with NV AMD. We identified a disease-associated increase in miR-146a and a decrease in miR-106b and miR-152 in the vitreous humour which was reproducible in plasma. Moreover, miR-146a/miR-106b ratios discriminated patients with NV AMD with an area under the Receiver Operating Characteristic curve (ROC AUC) of 0,977 in vitreous humour and 0,915 in plasma suggesting potential for a blood-based diagnostic. Furthermore, using the AMD Gene Consortium (AGC) we mapped a NV AMD-associated SNP (rs1063320) in a binding site for miR-152-3p in the HLA-G gene. The relationship between our detected miRNAs and NV AMD related genes was also investigated using gene sets derived from the Ingenuity Pathway Analysis (IPA). To our knowledge, our study is the first to correlate vitreal and plasma miRNA signatures with NV AMD, highlighting potential future worth as biomarkers and providing insight on NV AMD pathogenesis.

| S-EPMC4991373 | biostudies-literature

A new look at adenovirus splicing

2014-03-25 | GSE54583 | GEO

A new look at adenovirus splicing

Project description:Adenovirus type 2 RNA splicing sites were mapped by using deep cDNA sequencing. The majority of the previously identified splice sites were detected. In addition, novel splicing sites were identified Total RNA obtained from four time stages of human primary lung fibroblast cells IMR-90 infected by adenovirus type 2 compared to the control mock-infected by adenovirus type 2.

2014-03-25 | E-GEOD-54583 | biostudies-arrayexpress

Altered expressions of transfer RNA-derived small RNAs and microRNAs in the vitreous humour of proliferative diabetic retinopathy.

Project description:To reveal the expression profiles of transfer RNA-derived small RNA (tsRNA)s and microRNA (miRNA)s in the vitreous humour of proliferative diabetic retinopathy (PDR).

2022-06-10 | GSE199852 | GEO

Measurements of reducing end groups on bovine vitreous-humour hyaluronic acid by reaction with [14C]cyanide.

Project description:Bovine vitreous-humour sodium hyaluronate was purified by precipitation with cetylpyridinium chloride, CsCl-density-gradient sedimentation and gel-permeation chromatography. The number of reducing end groups in two similarly prepared hyaluronate samples was determined by reaction with K14CN, and measurements of intrinsic viscosity were performed to determine whether this reaction caused degradation of the hyaluronate. The intrinsic viscosity of one hyaluronate sample was 192ml/g, compared with a value of 187ml/g after reaction with [14C]cyanide, which indicates that the labelling reaction did not cause depolymerization of the hyaluronate. The Mr calculated from these viscosity values is approx. 60000. Fractionation of the [14C]cyanide-labelled hyaluronate by gel chromatography showed that it was composed of a polydisperse population of molecules with calculated chain lengths, based on the ratio of [14C]cyanide to uronic acid, ranging in molecular weight from 9000 to 264000, with an average Mr of 63200. On the basis of these measurements it is concluded that reaction with [14C]cyanide does not cause degradation of bovine vitreous-humour hyaluronate polysaccharide chains and that reaction with [14C]cyanide can be used to determine the molecular weight of this hyaluronate.

| S-EPMC1153879 | biostudies-other

Induction of posterior vitreous detachment (PVD) by non-enzymatic reagents targeting vitreous collagen liquefaction as well as vitreoretinal adhesion.

Project description:Induction of posterior vitreous detachment (PVD) by pharmacologic vitreolysis has been largely attempted through the use of enzymatic reagents. Ocriplasmin has been the only FDA-approved clinical reagent so far. Several adverse effects of ocriplasmin have emerged, however, and the search for alternative PVD-inducing reagents continues. Since i) collagen forms an important structural component of the vitreous, and ii) strong vitreo-retinal adhesions exist between the cortical vitreous and the internal limiting membrane (ILM) of the retina, an effective PVD-inducing reagent would require both, vitreous liquefaction, and concurrent dehiscence of vitreoretinal adhesion, without being toxic to retinal cells. We designed a combination of two reagents to achieve these two objectives; a triple helix-destabilizing collagen binding domain (CBD), and a fusion of RGD (integrin-binding) tripeptide with CBD (RCBD) to facilitate separation of posterior cortical vitreous from retinal surface. Based on in vitro, ex-vivo, and in vivo experiments, we show that a combination of CBD and RCBD displays potential for safe pharmacologic vitreolysis. Our findings assume significance in light of the fact that synthetic RGD-containing peptides have already been used for inhibition of tumor cell invasion. Proteins such as variants of collagen binding domains could have extended therapeutic uses in the future.

| S-EPMC7237681 | biostudies-literature

Vitreous Wiping, a new technique for removal of vitreous cortex remnants during vitrectomy.

Project description:PurposeUnremoved vitreoschisis-induced vitreous cortex remnants (VCR) are associated with macular pathology. When present on the retinal periphery, they may play a role in proliferative vitreoretinopathy and retinal detachment after vitrectomy. Existing instruments for their removal involve substantial risk of iatrogenic retinal damage. Purpose of this study was to evaluate the use of a new technique, Vitreous Wiping, for removal of VCR during vitrectomy.MethodsProof-of-concept case series of six eyes (six patients) treated with vitrectomy for various pathologies (macula-on and macula-off retinal detachment, macular hole, macular pucker and vitreous floaters). Vitreous cortex remnants on the surface of the retina were visualized with triamcinolone and removed by Vitreous Wiping with a rectangular piece of polyvinyl alcohol (PVA) held with intra-ocular forceps. Visual acuity and clinical course were assessed during a follow-up of 6 months. All eyes underwent postoperative macular optical coherence tomography. Eyes without preoperative macular pathology, underwent retinal sensitivity testing and eyes without paracentral pathology underwent visual field analysis.ResultsVitreous cortex remnants could be removed completely in all eyes. There were no intra- or postoperative complications. We observed that PVA is soft like a sponge and vitreous sticks to it, making Vitreous Wiping easier and safer, compared to alternative instruments. Visual acuity improved in all eyes. Microperimetry and visual field analysis revealed no abnormalities related to Vitreous Wiping.ConclusionVitreoschisis-induced VCR can be removed effectively and safely from the retinal surface by Vitreous Wiping. Larger studies are needed to confirm this promising finding and its potential impact.

| S-EPMC6766987 | biostudies-literature

Human Vitreous Collagen Fragments Dimension As a Function of Vitrectomy Cut Rate.

Project description:PurposeTo 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.MethodsFluid 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.ResultsVitreous 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.ConclusionsVitreous 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 relevanceIncreasing 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.

| S-EPMC8963665 | biostudies-literature

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