Studies on a distinct fraction of bovine vitreous body collagen

Proteomic Analyses of Vitreous in Proliferative Diabetic Retinopathy: Prior Studies and Future Outlook

Vitreous fluid is becoming an increasingly popular medium for the study of retinal disease. Numerous studies have demonstrated that proteomic analysis of the vitreous from patients with proliferative diabetic retinopathy yields valuable molecular information regarding known and novel proteins and pathways involved in this disease. However, there is no standardized methodology for vitreous proteomic studies. Here, we share a suggested protocol for such studies and outline the various experimental and analytic methods that are currently available. We also review prior mass spectrometry-based proteomic studies of the vitreous from patients with proliferative diabetic retinopathy, discuss common pitfalls of these studies, and propose next steps for moving the field forward.

Ultrastructure of hyaluronic acid and collagen in the human vitreous

The ultrastructure of hyaluronic acid (HA) and collagen in the human vitreous was investigated. After fixation with 4% glutaraldehyde and 0.1% cetylpyridinium chloride (CPC), sectioned blocks of retina and attached vitreous body were stained with 500 ppm ruthenium red (RR) in 1.25% glutaraldehyde, postfixed with 500 ppm RR in 2% OsO4, and embedded in Epon 812. In addition, collagen II immunostaining was done. Collagen fibrils were coated with amorphous material believed to be HA. No amorphous material was seen in the fibrils in the cortical areas adjacent to the retina, but the amount of material gradually increased toward the center of the vitreous body. By using anticollagen II antibody, we showed the presence of collagen II, often oriented perpendicular to the surface. The central vitreous demonstrated some dense materials that were collagen fibrils packed into bundles of parallel fibrils. In summary, collagen fibrils contained little HA in the cortical areas adjacent to the retina, but they were packed into bundles of parallel fibrils in the central vitreous.

Reaggregation behavior of different types of collagen in vitro: variations in the occurrence and structure of dimeric segment long-spacing collagen

Segment long-spacing collagen (SLS) can be precipitated from solutions of collagen using ATP as the inducing agent. Dimeric SLS aggregates have been observed in addition to monomeric SLS. We have compared collagen types I, II, III, and V with respect to their ability to form dimeric SLS in vitro. These collagen types were isolated from bovine tissues and characterized by polyacrylamide slab gel electrophoresis of the respective alpha-chains. Only monomeric SLS can be detected in preparations of collagen types I and III. Dimeric SLS, on the other hand, accounts for the majority of the crystallites seen in preparations of collagen types II and V. Dimeric SLS from both collagen types II and V reveal overlap zones at the carboxy-terminal ends of the collagen molecules. However, dimeric SLS from collagen types II and V differ with respect to their overlap distances. Significant portions of the triple helical domains of collagen molecules are occupied by the overlap region of dimeric SLS from type II collagen. On the other hand, dimeric SLS from type V collagen is composed of molecules overlapping only at their short nonhelical telopeptides. It is concluded that the ability of collagen molecules to aggregate into dimeric SLS under defined experimental conditions is collagen type dependent.