Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: T20B12 .5
 956,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have been studying composites of synthetic polymers and proctase-treated bovine collagen (telopeptide-poor collagen). In a previous paper, it is described that one of our composites appears to have a high tissue affinity, because it was found under a scanning electron microscope, well bonding the living tissue 6 weeks after implantation in the rabbit subcutaneous tissue. In the present study, the composites were also implanted in the subcutaneous tissue in rabbits to observe the mode of its bonding to the living tissue, and at the same time the bonding force was measured at various intervals during a period of 1.5 years, to observe the degree and duration of the effect of the composition, and further to study the optimal conditions for preparation of such a composite. As a method of composition, ultraviolet radiation and glutaraldehyde treatment were also comparatively examined, besides gamma-radiation that had been employed in a previous study. As the results, it is revealed that the composite bonds to the living tissue in such a manner that a portion of the collagen part is digested and absorbed to be replaced by the invading connective tissue and a part of collagen near the surface of the synthetic polymers had escaped digestion to combine with the rabbit's own collagen fiber. From these results we like to insist that the mode of reaction of our composites may be similar to real organization and be different in natur from mere encapsulation which was shown by the artificial materials hitherto in use to be considered to have a good tissue affinity. Therefor we think now the encapsulation is pseudoorganization. It is also shown that the bonding force of the composite to the living tissue and its duration depend chiefly on the degree of swelling, that is, the degree of intermolecular cross-linking, of the composed collagen part. Out of the gamma-radiated composites, those radiated 1--3 Mrads proved desirable in both tissue affinity and duration of tissue bonding, with a potent bonding force remaining effective even 1.5 years later, while the composite radiated with 5 Mrads or more proved poorer in these properties because of destruction of the collagen part, vastly varying in the properties. By ultraviolet radiation, it was easy to control the degree of swelling of collagen part with the radiation dose, however, this method gave a lower bonding force and a shorter duration of the force than gamma-radiation. The glutaraldehyde method allowed the collagen to remain over a long time, but gave the composite less tissue affinity than the other two methods.
 ...
PMID:Studies on composites of collagen and a synthetic polymer. Second report - mode of reaction of a laminar composite with living tissue, and results of long-term implantation. 10 79

The presence of specific Factor VIII/von Willebrand factor (FVIII/vWF) binding sites on human platelets has been demonstrated by using 125I-FVIII/vWF and washed human platelets. Binding is ristocetin-dependent and increases in proportion to the concentration of ristocetin from 0.2 to 1 mg/ml. Binding of 125I-FVIII/vWF to platelets can be competitively inhibited by unlabeled human or bovine FVIII/vWF, but not by human thrombin, fibrinogen, alpha 2-macroglobulin, equine collagen, or a lectin of Ricinus communis. Scatchard analysis of binding data indicated that the dissociation constant of FVIII/vWF receptors is 0.45--0.5 nM. There are 31,000 binding sites per platelet at 1 mg/ml of ristocetin concentration. The optimal pH range for binding is from 7.0 to 7.5. At a concentration of 2 mM, EGTA inhibits 86% of the binding; however, 20 mM of Ca++, Mg++, or EDTA have little effect. Binding sites for FVIII/vWF were found only on platelets, and no significant binding was detected with human erythrocytes or polymorphonuclear leukocytes.
 ...
PMID:Demonstration and characterization of specific binding sites for factor VIII/von Willebrand factor on human platelets. 10 91

Serum amyloid P-component (protein SAP) was found to bind in vitro to isolated amyloid fibrils of both primary and secondary types. The binding was strictly calcium-dependent, optimal uptake requiring at least 0.5 mM calcium ion. Using normal human serum as the source of protein SAP different fibril preparations became saturated with between 5--20 micrograms of SAP per mg dry weight of fibril. Isolated pure protein SAP bound in greater amounts. In control experiments SAP did not bind significantly to collagen fibrils, sheep erythrocytes, plastic shavings, or the following immobilized proteins: human kappa or lambda Bence-Jones proteins; human; rabbit or mouse IgG; human serum albumin. C-reactive protein, which resembles protein SAP structurally but has calcium-dependent specificity for different ligands, bound significantly to only one of five different amyloid fibril preparations.
 ...
PMID:Binding of serum amyloid P-component (SAP) by amyloid fibrils. 11 39

1. Rat tail-tendon collagen was coupled to activated Sepharose 4B at 2.5 mg of collagen/ml of gel. Chromatographic columns of this gel were calibrated with T2 virus (Vo) and Dnp-alanine (Vt). 2. The chromatographic behaviour of cartilage proteoglycans on the collagen-substituted gel was studied under conditions of varying ionic strength. Proteoglycan subunit obtained from bovine nasal cartilage, the proteoglycan obtained after digestion with chondroitnase ABC and purified chondriotin sulphate were all retarded on the collagen gel by an interaction that abolished at I0.17. Purified keratan sulphate and hyaluronic acid were not retarded. 3. A strong ionic interaction between cartilage proteoglycan and collagen was demonstrated to depend on the structure of the protein core of the proteoglycan.
 ...
PMID:Interaction of cartilage proteoglycans with collagen-substituted agarose gels. 12 83

Rats with subcutaneously implanted polyurethane sponges were exposed 6 hours daily for 7 days to high ambient atmospheric pressures (1.5, 2, 2.5 and 3 ATA). Another group was exposed 4 hours daily for 4 weeks to 3 ATA before inducing granulation tissue formation. 14C-proline was administered 16 hours before terminating the experiment. Free hydroxyproline, soluble and insoluble collagen and total noncollagenous protein were isolated from the 7-day granuloma and the amount and radioactivity of 14C-hydroxyproline and 14C-proline were determined. Seven days' graduated hyperbarism did not affect collagen synthesis; the maturation of collagen to insoluble forms was inhibited at 2 and 2.5 ATA, but not at 3 ATA. Stimulated degradation of collagen (free hydroxyproline) was observed at 2, 2.5 and 3 ATA. In animals subjected to long-term exposure at 3 ATA pressure, the collagen in the granuloma matured to insoluble forms more quickly. Biochemical changes were correlated with changes in the fine structure of the granulation tissue. The appearance of the fibroblast proteosynthetic apparatus was not influenced by hyperbarism. Progressive spherical transformation, fusion of mitochondria and lysosomal activation in the pericapillary fibroblasts occurred at 2, 2.5 and 3 ATA. In short-term experiment, the formation of cytosegresomes and cellular necrosis also contributed to the effect at 3 ATA, which is thus already a toxic pressure for granulation tissue.
 ...
PMID:Effect of hyperbarism on collagenous protein metabolism in granulation tissue. 12 87

Optical rotary dispersion spectra have been studied of methylene blue complexes of glycosaminoglycans and different derivates of chondroitin 4-sulphate (free and protein bound complexes of different molecular weights and degrees of sulphation). Structural requirements of Ch-4S induction of the extrinsic Cotton effect in methylene blue were formulated. This Cotton effect is supposed to reflect the right-handed helical structure of the polysaccharide molecules. Ch-4S displayed induced Cotton effect both in free and in protein bound form; molecular weight should exceed 2-3000 (at least 4-6 disaccharide units), degree of sulphation should exceed 3% sulphate-sulphur content (more than 0.5 sulphate per one disaccharide unit). For comparison the effect of different derivatives of Ch-4S on the rate of in vitro collagen fibril formation was investigated. Close correlation was found between the macrostructural characteristics and the possible biological effect of Ch-4S. The biological significance of the macrostructural properties of Ch-4S is discussed.
 ...
PMID:Biological significance of helical conformation of acid polysaccharides. 12 34

Scanning electron microscopy and high angle X-ray diffraction were used to define the relationship between collagen and elastin of bovine aortic wall. The diffraction pattern shows on one hand that the broad rings at 4.5 A and 9 A, due to elastin, do not orient on stretching and on the other hand, that the collagen rings at 11 A and 2.9 A start to orient at low elongations. These data together with scanning electron microscopy suggest a tight structural relationship between collagen and elastin that should influence the mechanics of deformation at all degrees of elongation.
 ...
PMID:X-ray diffraction and scanning electron microscopy of bovine media aortic wall. 14 60

Porcine aortae were digested with pepsin and the solubilised collagen molecules separated by differential salt precipitation at pH7.5. The fraction precipitated at 1.71 M NaCl was shown to comprise collagen type III as judged by its elution characteristics from CM-cellulose, its alpha-chain composition on sodium dodeclysulphate polyacrylamide gel electrophoresis, and amino acid analyses. Pepsin-derived type I collagen was recovered by precipitation at 2.56 M NaCl and similarly characterised. cultures of porcine arterial smooth muscle cells have been established and radiolabelling studies with [14Clproline have demonstrated that these cells synthesis and secrete the precursors of collagen types I and III into the culture medium. Ion-exchange chromatography of these secreted collagen molecules and gel filtration of their pepsin-derived alpha-chains have demonstrated that type III is the major collagen species present in the medium.
 ...
PMID:Characterisation of the major collagen species present in porcine aortae and the synthesis of their precursors by smooth muscle cells in culture. 14 63

Previous work has shown in experimental animals that lung contains extractable collagen of types I and II and possibly III and IV. The current studies describe the types of collagen which are found in normal newborn and adult human lung. Autopsy lung specimens were dissected into tissue which was cartilage free and tissue which contained cartilage. Pleura was excluded. Extraction of distal lung which did not contain cartilage by using 1.0 M NaCl and 0.5 N acetic yielded collagen having the characteristics on acrylamide gel electrophoresis and CM-cellulose chromatography of type I collagen [alpha 1(I)] alpha2. Newborn and adult type I lung collagen are similar as compared by amino acid analysis and cyanogen bromide peptide fragment analysis. Furthermore, distal lung type I collagen is very similar, if not identical, to that found in human skin. Human bronchial cartilage collagen is similar to that found in other human cartilages. Type II collagen, [alpha 1(III)], can be extracted from human distal lung using pepsin digestion and differential salt precipitation at 1.85 M sodium chloride. This distal lung type III collagen appears identical with that found in human skin. These data support the concept that normal human lung contains collagen of types I, II, and III, identical to that found elsewhere in the body. Current techniques have not revealed a unique lung collagen. This should lead to the studies which will investigate the types and ratios of the collagens in diseased human lung.
 ...
PMID:Normal newborn and adult human lung collagen--analysis of types. 14 5

The inflammatory response was studied using the contents (mucopolysaccharides and collagen of granuloma induced by turpentine in rats fed for 28 days after weaning), with semi-synthetic, isocaloric diets containing 0, 3.5, 9, 26 or 81% protein in the form of casein or with a laboratory chow. When the wet and dry weights and the water content of the granuloma are expressed in absolute values they show a substantial drop when the protein intake is low or excessive. If however the wet weight of the granuloma is expressed per 100 g of body weight, the differences become no longer significant, hence the importance of the nutritional state of the animal at the time of investigation. Using this test of the anti-inflammatory action of substances, it is necessary to differenciate between actual anti-inflammatory action and direct or secondary effects of the substance on the growth and behaviour of the animal. The levels of mucopolysaccharide drop in rats fed on hypo or hyper-proteinic diets, this would seem to be a sign of the decrease in the intensity of the anti-inflammatory response. What is more, the collagen itself undergoes modifications; there is a shift towards greater solubility of the fractions which would seem to indicate that a drop or a increase in the protein intake brings about a change in the processes of reticulation and maturation of the collagen; several hypothesis can be put forward to explain this phenomenon.
 ...
PMID:[Dietary protein levels, and experimental inflammation in the rat]. 15 21


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>