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Query: T20B12 .5
 956,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effect of proline analogues on biosynthesis and properties of collagen in chick embryo cartilage was studied. Azethidine-2-carboxylic acid, 3,4-dehydroproline, cis-fluoro-proline, cis-hydroxyproline and thiazolidine-4-carboxylic acid were found to inhibit the incorporation of 14C-proline into proteins by 66-89%. Introduction of proline analogues, instead of the amino acid, into the polypeptide chains of collagen caused the impairment of the enzymatic hydroxylation of the proline residues (formation of hydroxyproline). 3,4-dehydroproline possessed the highest inhibitory effect (80%) on formation of hydroxyproline. When it was introduced into alpha-chains of protocollagen, 3,4-dehydroproline inhibited 1.5-6-fold the cleavage of the protein by bacterial collagenase.
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PMID:[Biosynthesis and properties of collagen forming in the cartilage of chick embryos in the presence of various proline analogs]. 19 18

Two genetic types of collagenous proteins, type I and type III, were isolated by extraction and differential salt precipitation from rat skin. The yield of collagen precursors was increased by injecting animals with colchicine 30 min before sacrifice to inhibit secretion of collagen. DEAE-cellulose chromatography was used to separate collagen from collagen precursors. Although these preparations contained more type I collagen than type III collagen, there were always more type III than type I precursors. The precursor chains of type I fractions were separated on CM-cellulose chromatography after denaturation. Three precursor forms were found for each collagen alpha chain, a complete chain (proalpha chain), and a precursor chain with only an amino-terminal (pNalpha chain) and carboxy-terminal extension (pCalpha chain). Species differences were demonstrated between rat collagen precursors and other species using rat calvaria (frontal and parietal) bones extracted with either 0.5 N acetic acid or neutral salt buffers containing protease inhibitors. Native rat procollagen elutes earlier than chicken or human procollagen on DEAE-cellulose chromatography and does not separate significantly from the pC collagen form. The collagenase resistant amino terminal peptides of rat pNalpha1 and pNalpha2 were the same size (16 000) but could be separated by DEAE-cellulose chromatography.
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PMID:Characterization of collagen precursors found in rat skin and rat bone. 19 97

Collagenolytic activity has been demonstrated in the early phase of chemical carcinogenesis of mouse skin following 3-methylcholanthrene application dropwise in acetone or painted on the skin in benzene. In addition very high levels of collagenase could be detected in mouse skin papillomas and carcinomas. In all the tissues investigated, collagenase activity was extracted from the 6000 X g sediment of tissue homogenates with 5 M urea in 50 mM Tris-HCl buffer, pH 7.5. After dialyzing the extract, the enzyme was precipitated with ammonium sulfate and the activity determined against 14C-collagen substrate in solution. This procedure was found suitable for the detection and estimation of collagenase activity in skin tissues with high turnover of collagen and thus offers an attractive alternative to tissue culture methods.
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PMID:Extractable collagenase and carcinogenesis of the mouse skin. 20 Mar 99

Chronic kidney insufficiency, caused by subtotal nephrectomy, did not lead to distinct alterations in hydroxyproline concentration in blood and to its excretion in rats within 1-1.5 months after the operation. Content of salt-soluble collagen was decreased in diaphyses of rat tubular bones in chronic kidney insufficiency; in the epiphyses (with metaphyses) content of the collagen fraction was increased, but the concentration of non-soluble collagen was unaltered. Decrease in content of salt-soluble collagen in diaphyses in chronic kidney insufficiency was similar to that in experimental vitamin D deficiency. The decrease might be due to impairment in formation of the active form of vitamin D-1,25-dihydroxycholecalciferol. Other pathogenetic factors (effect of uremic toxins and stress) were apparently of primary importance for development of impairments of collagen metabolism in epiphyses. Dihydrotachysterol, the structural analogue of 1,25-dihydroxycholecalciferol, normalized the alterations in content of salt-soluble collagen in diaphyses and did not affect the impairments of collagen metabolism in epiphyses of rat bones in chronic kidney insufficiency.
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PMID:[Bone tissue collagen and vitamin D in chronic kidney insufficiency in rats]. 20 93

1. The neutral collagenase released into the culture medium by explants of human skin tissue was purified by ultrafiltration and column chromatography. The final enzyme preparation had a specific activity against thermally reconstituted collagen fibrils of 32mug of collagen degraded/min per mg of enzyme protein, representing a 266-fold increase over that of the culture medium. Electrophoresis in polyacrylamide disc gels showed it to migrate as a single protein band from which enzyme activity could be eluted. Chromatographic and polyacrylamide-gel-elution experiments provided no evidence for the existence of more than one active collagenase. 2. The molecular weight of the enzyme estimated from gel filtration and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis was approx. 60000. The purified collagenase, having a pH optimum of 7.5-8.5, did not hydrolyse the synthetic collagen peptide 4-phenylazobenzyloxycarbonyl-Pro-Leu-Gly-Pro-d-Arg-OH and had no non-specific proteinase activity when examined against non-collagenous proteins. 3. It attacked undenatured collagen in solution at 25 degrees C, producing the two characteristic products TC(A)((3/4)) and TC(B)((1/4)). Collagen types I, II and III were all cleaved in a similar manner by the enzyme at 25 degrees C, but under similar conditions basement-membrane collagen appeared not to be susceptible to collagenase attack. At 37 degrees C the enzyme attacked gelatin, producing initially three-quarter and one-quarter fragments of the alpha-chains, which were degraded further at a lower rate. As judged by the release of soluble hydroxyproline peptides and electron microscopy, the purified enzyme degraded insoluble collagen derived from human skin at 37 degrees C, but at a rate much lower than that for reconstituted collagen fibrils. 4. Inhibition of the skin collagenase was obtained with EDTA, 1,10-phenanthroline, cysteine, dithiothreitol and sodium aurothiomaleate. Cartilage proteoglycans did not inhibit the enzyme. The serum proteins alpha(2)-macroglobulin and beta(1)-anti-collagenase both inhibited the enzyme, but alpha(1)-anti-trypsin did not. 5. The physicochemical and enzymic properties of the skin enzyme are discussed in relation to those of other human collagenases.
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PMID:Purification, characterization and inhibition of human skin collagenase. 20 94

Traditionally, ligaments and tendons (L and T) have been regarded as metabolically inert structures. However, sufficient biochemical evidence on the metabolism of collagen has indicated that such a concept is no longer tenable. To determine whether L and T respond to increased or decreased levels of chronic exercise, studies were undertaken to measure their aerobic capacities. For comparative purposes, similar measurements were obtained from liver and skeletal muscles secured from normal and hypophysectomized male rats. Oxygen consumption and cytochrome oxidase (CO) activity was recorded from cell suspensions that had been prepared with the inclusion of collagenase and with elastase added to the medium. The O2 results showed that L and T had values that were approximately 10 times lower than liver tissue and 7.5 times less than the means from skeletal muscles. Hypophysectomy caused marked reductions in O2 uptake of liver and muscle tissues; but had no impact on L and T. When CO activity of these connective tissues were evaluated, immobilization and hypophysectomy caused significant reductions that ranged from -36% to -59% respectively. Training, on the other hand, resulted in increases of less than 10% in the activity of this enzyme within L and T while being elevated in muscle tissue by 58%. It was concluded that the metabolic activity of L and T was lowered with decreased levels of physical activity but it was unclear why chronic exercise did not produce the opposite effect.
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PMID:Physical activity and hypophysectomy on the aerobic capacity of ligaments and tendons. 20 28

Serum angiotensin-converting enzyme in a patient with type 2 acute neuronopathic Gaucher's disease (242 nmol/min/ml) was 10.8 times higher than values for eight patients with other hereditary neurologic abnormalities (22.5 +/- 2.0) and 9.4 times higher than those for 12 patients with other diseases (25.7 +/- 2.6) (P less than 0.001). Serum lysozyme was not elevated in the patient with type 2 Gaucher's disease. These results indicate that elevated serum angiotensin-converting enzyme in an infant with neurologic involvement and hepatosplenomegaly is suggestive of the possibility of type 2 Gaucher's disease. Typical Gaucher's cells and fibrosis were observed by light and electron microscopy of the liver. An aspect hitherto unreported in Gaucher's disease or in the liver was that approximately 20% of the collagen fibrils were of the long-spacing type, with periodicity of 1,000 to 1,100 A and diameters of 900 to 1,500 A.
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PMID:Marked elevation of serum angiotension-converting enzyme and hepatic fibrosis containing long-spacing collagen fibrils in type 2 acute neuronopathic Gaucher's disease. 20 29

The effects of gentamicin on three proteolytic enzymes were studied. Gentamicin was tested at concentrations of 0.5-500 microgram/ml. Trypsin was tested at 0.5 microgram/ml using p-tosyl-L-arginine methyl ester and at 0.1 and 0.5 microgram/ml using azocoll as the substrate. Chymotrypsin was tested at 0.1 and 0.5 microgram/ml with azocoll. A soluble [14C]collagen assay was used to measure activity of collagenase derived from Clostridium histolyticum. The profiles of proteolytic activity vs. gentamicin concentration were similar for all three enzymes. At lower concentrations of gentamicin (less than 70 microgram/ml), there were two peaks of enhanced protease activity generally followed by inhibition. These unusual multiphasic effects of gentamicin on three different proteases are not presently understood, but they imply a previously unreported mode of action for this antibiotic.
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PMID:Effects of gentamicin on trypsin, chymotrypsin, and collagenase. 21 Feb 40

The localization of antigenic components with cross-reactivity to a 52,000 dalton group specific glycoprotein (gp52) of the mouse mammary tumor virus (MMTV) in paraffin sections of human breast carcinomas is described using an indirect immunoperoxidase method. This method was first optimized on paraffin sections of mouse mammary tumors. The specificity of the reaction observed in the human tissues was established by absorption of the specific IgG with: a) purified gp52; b) several relevant and irrelevant viral preparations; c) normal human plasma, leukocytes, breast tissue, milk, actin, collagen, and hyaluronic acid; d) sheep erythrocytes, bovine mucin and fetal calf serum. Only MMTV and purified gp52 eliminated the immunohistochemical reaction in human breast tumors. Positive reactions were seen in 171 of 376 (45.5 percent) randomly selected breast carcinomas of various histopathologic types, while negative reactions were obtained in all 137 normal and benign cases tested. In those invasive tumors with an intraductal component, a higher percentage (63.9 percent) of positive cases was seen. A positive reaction of different specificity was observed in foci of apocrine metaplasia. With one exception, 99 carcinomas from 13 organs other than breast and eight cystosarcomas were negative.
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PMID:Immunohistochemical evidence for RNA virus related components in human breast cancer. 22 91

Epithelial cells from the toad urinary bladder have been grown in continuous culture. Many of the cells resemble the granular cell type of the urinary bladder. They form an epithelium with typical tight junctions and gap junctions. The transport properties of two cell lines have been examined. When cells of the line designated TB-M or of line TB-6c are grown on collagen-coated nucleopore filters, epithelia are formed that have transepithelial potential differences of 40 and 20 mV, resistances of 5000 and 10,000 omega-cm2, and short-circuit currents (ISC) of 8.5 and 2.5 muA/cm2, respectively. Net mucosa to serosa sodium transport accounts for all of ISC in line TB-M and for 70% of ISC in line TB-6c. Vasopressin, which stimulates adenylate cylase and ISC in the intact bladder, has no effect on the cells in culture. Cyclic AMP stimulates ISC and lowers resistance in both lines. Aldosterone stimulates ISC in both lines. This is accompanied by a fall in resistance in line TB-M and no change in resistance in line TB-6c. Amiloride inhibits ISC in TB-M cells under basal conditions and after stimulation by aldosterone. In line TB-6c amiloride has no effect under basal conditions but lowers ISC of aldosterone-treated cells to the basal level. Thus, the cells have retained the ability to form oriented, high-resistance epithelial membranes that manifest hormone-sensitive transepithelial sodium transport.
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PMID:Toad urinary bladder epithelial cells in culture: maintenance of epithelial structure, sodium transport, and response to hormones. 22 98


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