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G Cetta

Publications and source records attributed to G Cetta.

98 records · Page 6Linked to original sources
PubMedDate not supplied

A simple method for quantitative estimation of collagen type III to type I ratio in soft tissues.

In the present paper a relatively rapid and simple method for estimating the ratio of collagen type III to type I in soft tissues is proposed. The ratio Gly/Ala is determined in pure collagen samples obtained from pepsin digests of the tissues. Since this ratio varies linearly depending on the composition of the mixtures of the two collagen types, it is shown that the percentage content of the two collagen types is easily calculated.

Adult↗
PubMedDate not supplied

Influence of flavonoid-copper complexes on cross linking in elastin.

A protective and curative effect of some flavonoids on collagen maturation in lathyrism has been previously demonstrated. This action appeared to involve cross linking of collagen. This paper deals with the effect in vitro of flavonoids and flavonoid-copper complexes on the oxidative deamination of lysine epsilon-amino groups in [4,5-3H]-lysine-labelled elastin. Flavonoids alone do not affect the reaction but it is evident that some flavonoid copper complexes are strongly effective: the aldehyde groups that are quickly formed then enable cross linking to occur. The lysine epsilon-amino groups of elastin are specifically concerned: in fact no effect was observed on free [4,5-3H]-lysine or on [4,5-3H]-lysine-labelled proteins obtained from mouse liver. The lysyl oxidase seems to interfere with the flavonoid-copper complees to regulate the oxidative deamination of lysine epsilon-amino groups.

Animals↗
PubMedDate not supplied

Hypothesis on the role of hydroxylysyl glycosides in collagen fibre organization.

Hydroxylysine (Hyl) glycosides were determined both on the collagen produced by in-vitro cultures of human skin fibroblasts and pig articular chondrocytes and on the insoluble collagen extracted from bovine cornea and sclera. The disorganized collagen present in the culture medium showed a Hyl di- to mono-glycoside ratio markedly higher than the molecules extracted from the cell layer, where electron microscopy investigations demonstrated the real presence of collagen fibres. Moreover in bovine cornea the insoluble collagen showed a ratio Hyl di- to mono-glycoside significantly higher than in sclera, which, on the contrary, possesses fibres with larger mean diameter. The possible conversion of Hyl diglycoside to monoglycoside was suggested by the demonstration of an alpha (1----2) glucosidase activity on Hyl diglycoside , in an enzyme extract from cultured human skin fibroblasts. A role for the processes of collagen glycosylation and deglycosylation was thus considered.

Animals↗
PubMedDate not supplied

Proteoglycan modifications in cultured osteogenesis imperfecta skin fibroblasts.

The PGs produced in the growth medium by skin fibroblast cultures from two O.I. affected patients were investigated. After density gradient centrifugation, in the most dense fraction two main families of molecules appeared. The patient with the more severe clinical picture showed a lower content of the PGs with the highest molecular weight. The GAG composition of PGs was different in the two patients. The more severely affected one showed an increase of HS and a decrease of ChS content, in agreement with the lower value of galactosamine to glucosamine ratio in urinary GAGs.

Cells, Cultured↗
PubMedDate not supplied

Hydroxylysine glycosides: preparation and analysis by reverse phase high performance liquid chromatography.

Hydroxylysine diglycoside was prepared from hydrolyzed sponge by a combination of ion-exchange chromatography and gel filtration. The product obtained was chemically pure on amino acid analyzer and was active as substrate of the enzyme alpha-(1----2)glucosidase. Hyl monoglycoside was prepared by mild acid hydrolysis from diglycoside. A reverse phase HPLC system was devised for Hyl glycosides, hydroxylysine and other basic amino acids. The separation was achieved using an octadecyl bonded silica column on the compounds derivatized with dabsyl chloride to produce di-dabsyl derivatives. Elution was followed in the visible region at 436 nm. In the conditions used no or very low amount of mono-dabsyl derivatives was observed. Hyl di- and monoglycoside resulted a mixture of two diastereoisomers, which form during the alkaline hydrolysis. The separation of the diastereoisomers of each compound depended on pH and ionic strength of the eluent in the HPLC column, whereas they were not separated by our short column on amino acid analyzer. The HPLC system was also used for the analysis of Hyl glycosides on two collagen preparations.

Animals↗
PubMedDate not supplied

Glycosaminoglycan alterations in osteogenesis imperfecta.

Urinary GAGs from patients affected with Osteogenesis Imperfecta (O.I.) type I, type II and type III - according to Sillence et al. (1979) - have been investigated. Galactosamine to glucosamine ratio resulted significantly decreased in O.I. type II and III, whereas smaller differences in the mildest type of the disease were observed. Cellulose polyacetate electrophoresis of urinary GAGs purified from some patients showed the presence of a slowly moving polysaccharide substance, which did not appear in normal subjects. Moreover some pathological fractions, mainly constituted of ChS on the basis of chemical analysis and electrophoretic behaviour, were not digested by testicular hyaluronidase and presented anomalous structures as compared with the corresponding normal ones. These results seem to indicate that in some forms of O.I. the metabolic defect(s) not only affects the synthesis or the catabolism of a particular type of collagen, but also involves the proteoglycan component of the connective tissue.

Adolescent↗
PubMedDate not supplied

Water soluble proteoglycans from bovine duodenal mucosa.

Glycosaminoglycan-protein complexes were extracted from bovine duodenal mucosa with distilled water, resulting in solubilization of a fraction of the total proteoglycan of the tissue. The extracted material was purified by anion exchange chromatography on DEAE-Sephadex A-25, and then characterized by chemical analysis and by fractionation on Dowex 1. By using these procedures, two major fractions were identified, which were eluted from Dowex with 1.0-1.25 M NaC1 and with 1.5-1.75 M NaC1 respectively. Analyses showed that both fractions were mainly composed of glucosamine-containing, hyaluronidase-resistant polysaccharides, which were identified by their N-sulphate: D-glucosamine and total sulphate: D-glucosamine ratios as heparan-sulphate in the less acidic fraction, and as heparin in the more acidic fraction. Dermatan sulphate molecules were also present in both preparations, with an approximate ratio 1:3 to the glucosamine-containing polysaccharides. Solubility behaviour of the complexes formed by the isolated polyanionic molecules with cetylpyridinium chloride was strongly modified by papain digestion of the duodenal material. This reduction of molecular size of papain treatment suggests that the molecules extracted with water from duodenal mucosa are complex proteoglycans, perhaps in the native state.

Amino Acids↗