Collagen-like Material Research Articles

In vitro demonstration of a particular affinity of glomerular basement membrane and collagen for DNA. A possible basis for a local formation of DNA-anti-DNA complexes in systemic lupus erythematosus.

In vitro, collagen and collagen-like material in GBM, were demonstrated to have a particular high affinity for any DNA tested (mammalian, bacterial, viral, and plant). GBM fixed DNA 40-80 times more than HGG and BSA and 10-40 times more than bacterial LPS. GBM has a higher affinity for SSDNA than for DSDNA. This binding was inhibited at low pH, low ionic strength, and in the presence of anionic detergents, indicating that the highly negatively charged DNA may interact with the basic site on collagen or GBM by electrostatic forces. This interaction was competitively interfered with by DNA-binding proteins such as Clq. Complexes formed of DNA and anti-DNA antibodies did not exhibit the same binding property as free DNA. However, DNA which was already bound to GBM or to collagen could very efficiently bind anti-DNA antibodies and form immune complexes which would remain on these structures. The biological significance of the binding of DNA to GBM or to collagen should be particularly considered in relation to the pathogenesis of SLE. It is possible that DNA released from disrupted or degenerating cells would bind to surrounding collagen fibers or to basement membranes and then act as an immunoabsorbant for circulating anti-DNA antibodies. Some evidence for an in vivo binding of SSDNA to renal structures was obtained in mice treated with bacterial LPS 2 days before the injection of SSDNA.

Studies of normal and nephritic rat glomerular basement membrane

Solubilization of the normal glomerular basement membrane with various solvents revealed that the material is held together by hydrogen and disulfide linkages as well as ionic salt bridges which ionize at around pH 10.0. Pronase digestion indicated that differences in susceptibility to enzyme digestion exist between normal and nephritic membrane. Titration of a urea-insoluble material indicated that some alteration must have taken place in the association between various components of the nephritic basement membrane. Chemical analysis of alkali-solubilized fractions suggested that greater alkali susceptibility of the nephritic material may be present. A collagen-like material resembling both tendon and dog basement membrane collagen in its amino acid composition was isolated. It contained 10% hexose, but in addition to glucose and galactose, mannose was also detected. A glycopeptide fraction obtained by pronase and collagenase digestion has a carbohydrate composition similar to the collagen-like material above. These substances probably represent incompletely digested fragments of the basement membrane.

The effects of lathyrism on renal chemistry, anatomy and function.

SummaryA significant increase was induced by lathyrism in the small fraction of collagen-like material solubilized from rat glomeruli. An increased affinity and staining by PTA of fibrils within the GBM of lathyritic rats was found by electron microscopy, and also probably reflects an alteration in the collagen-like moiety of the GBM by APN, a material known to affect the cross-linking of collagens. No change in total proteinuria was found in lathyritic rats, nor other major changes in renal structure by conventional microscopy, electron microscopy, or specialized stains of the sialoprotein layer of the glomerulus. Further study of physicochemical alterations induced in the GBM combined with methods to evaluate glomerular permeability, may reveal the location and nature of the filtration barrier.

The nephropathy of the nail-patella syndrome: Clinicopathologic analysis of 11 kindred

Seventy-two members of 11 kindred with the nail-patella syndrome were studied. Twelve patients who had electron microscopic examinations of renal tissue had abnormalities of the glomerular basement membrane. An unaffected family member did not. This lesion consisted of irregular basement membrane thickening, epithelial foot process fusion and the presence of fibrillar collagen-like material within the substance of the membrane. Many patients also showed areas of increased lucency giving the membrane a “moth-eaten” appearance. The presence of the ultrastructural lesion bore no relation to the presence or absence of abnormalities by light or immunofluorescent microscopy and also no relation to demonstrable alterations of renal function. The determinants of clinically significant nephropathy are unknown but in most patients the prognosis is favorable.

Acid mucopolysaccharides and proteins of bovine whole brain, white matter and myelin

1. 1. In a study of the acid mucopolysaccharides of bovine brain, only hyaluronic acid and chondroitin sulfates A and C were detected, with approximately equal concentrations of hyaluronic acid and chondroitin sulfate both in whole brain and in white matter. The ratio of chondrotin sulfate A to chrondroitin sulfate C is, however, considerably higher in grey matter than in white matter. The concentration of total acid mucopolysaccharides in bovine whole brain was found to be 0.03%, with one-half that amount in white matter. However, on a lipid-free dry weight basis the concentration is identical (0.27%) in white matter and whole brain. 2. 2. The molecular weight of a preparation of purified brain hyaluronic acid was calculated to be 140 000 on the basis of intrinsic viscosity. The hyaluronic acid contained less than 0.2% arabinose. 3. 3. No collagen-like material was found in a lipid-free residue from whole brain, suggesting that a large part of the brain acid mucopolysaccharides are of nonconnective tissue origin. 4. 4. Four protein fractions from a preparation of purified bovine myelin were studied and compared with two similar fractions from white matter with respect to the presence of acid mucopolysaccharides, amino acid composition and phosphorus content. Although acid mucopolysaccharides were not found in brain myelin, three of the four myelin protein fractions contained approx. 1% glucosamine, probably as a component of glycoproteins.

A Histochemical Study of the Organic Matrix of Hen Egg-Shells

ABSTRACT A study of the organic material of the hen egg-shell has been made by the use of recognized histochemical techniques. It has been found that, in the so-called spongy layer of the shell, the organic matrix consists of a protein / acid mucopolysaccharide complex. The organic material of the mammillary layer appears to be more concentrated in a central core, and is somewhat different in that it contains fat and a reducing substance. The protein / acid mucopolysaccharide complex is a collagen-like material, but is probably not collagen itself because the protein portion is low in hydroxyprob’ne and the acid mucopolysaccharide is most likely mucoitin and not chondroitin sulphuric acid. The results are discussed in relation to shell calcification and it is suggested that the protein / acid mucopolysaccharide complex is first firmly attached to the keratin of the membrane, but once this is accomplished it links on to material of its own kind. Calcification proceeds simultaneously, but near the points of contact with the membrane (i.e. in the core of each mammilla) calcification is not so intense as it is in the rest of the shell.

Particle interaction in solutions derived from ox vitreous humor.

Solutions made by homogenization of vitreous humor exhibit anomalous viscosity at low shear rates due to interaction between hyaluronic acid and a hydroxyproline-containing material similar to collagen. The latter can be removed by filtration or centrifugation to give a solution whose viscosity is due to hyaluronic acid. On concentration the viscosity of the latter remains independent of shear rate and it is concluded that hyaluronic acid in the vitreous humor is not greatly asymmetric. There is no evidence that the soluble protein of vitreous humor contributes to the viscosity. Hyaluronic acid in vitreous humor is not in chemical combination with protein. The interaction between the hyaluronic acid and the collagen-like material is ascribed to weak, coulombic forces.

Studies of the Mesogloea of Coelenterates: I. Histology and Chemical Properties

ABSTRACT Evidence is presented to show that the mesogloea of the coelenterates examined, including Aequorea, Aurelia, Cyanea, Chrysaora, Calliactis, and Metridium contains collagen-like material in the form of fibres of varying sizes. Cells are also present in the mesogloea of some species but there is little evidence concerning their functions. In Aequorea and the Scyphozoa examined the fibres appear to be straight and very transparent in life but on injury and fixation they adopt a convoluted and irregular appearance. Cells are present in Aurelia and form about 0· per cent, of the mesogloea by volume but are absent from the other medusae examined. The mesogloea of actinians is of a more densely fibrous character than that of medusae. In Calliactis and Metridium the crossed fibrillar structure present is determined by mechanical forces acting on the tissue. Reference is made to the physical properties of Calliactis mesogloea, which are described in another paper. The material is tough, almost resembling cartilage in its consistency, and has considerable tensile strength. The chemical nature of the mesogloea is shown to be primarily that of a protein of which the amino-acid composition is similar to that of vertebrate collagen. The role of the mesogloea in the life of the animal is that of a base for the muscles, a limiter of the body volume, and a resister of rapid movements, both those caused by the musculature and those enforced by the environment without. Its viscous-elastic properties are well adapted to this role since the elastic component, having a short timescale, can provide a restoring force for rapid deformations.