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C Balduini

Publications and source records attributed to C Balduini.

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

Erythrocyte spectrofluorometric abnormalities in myotonic dystrophy during "in vitro" aging.

The possibility in Myotonic dystrophy (MyD) that a decreased ATP utilization by the membrane may produce modifications in glycoprotein structure and/or in the supramolecular arrangement of some membrane proteins was investigated in human erythrocytes: a) by determining the membrane sialic acid content and the cellular ATP concentration in eight cases of MyD; b) by evaluating the stability of the membrane glycoprotein structure by in vitro ageing experiments; c) by testing the presence of high molecular weight aggregates of proteins on the membrane; d) by evaluating the physico-chemical properties of the membrane by 1-anilino 8-naftalensulfonate as a fluorescent probe. Our evidence suggests that ATP concentration and membrane sialic acid content are within normal values. Only in two cases did a decreased stability of membrane glycoproteins occur while the supramolecular assembly of membrane proteins could be considered as normal. The fluorescent probe behavior after in vitro aging was indicative of a decreased polarity of its micro-environment.

Adenosine Triphosphate↗
PubMedDate not supplied

Isolation and characterization of two proteoglycans from bovine tendon.

Proteoglycans were extracted from bovine flexor digitorum profundus tendon (FDP) with 4 M-guanidine hydrochloride in the presence of proteinase inhibitors and purified by density-gradient centrifugation and ion-exchange chromatography. Tendon proteoglycans were fractionated into two major components, D1 and D2, and characterized by chemical analysis and enzymatic (chondroitinases and hyaluronidase) degradations. The two proteoglycans differ with respect to the structure of their glycan side chains; D1 chains were mainly chondroitinsulfate, whereas D2 contained 40% of dermatansulfate. In both proteoglycans keratansulfate chains are probably present. Tendon proteochondroitinsulfate was of larger size than proteodermatansulfate as judged by gel-chromatography on Sepharose 2B. Proteoglycan-collagen interactions were studied by affinity-chromatography on Sepharose 4B-collagen. Both proteochondroitinsulfate and proteodermatansulfate were resolved in two components, with different affinity for collagen. In proteodermatansulfate the component at higher affinity was predominant.

Animals↗
PubMedDate not supplied

Changes in composition of platelet membranes after "in vitro" incubation.

Platelet membranes were isolated by the glycerol lysis technique and incubated in Krebs-Ringer phosphate buffer, to determine their chemical modifications occurring during "in vitro" incubation. The main changes observed at the end of the incubation consist in a significant loss of protein components and in the nearly equimolar decrease of sialic acid and galactosamine. Aminoacid analysis indicate that mainly polar aminoacids are lost. SDS-polyacrylamide gel electrophoresis indicates that high molecular weight proteins disappear after incubation, while no relevant differences in the relative ratios between PAS-stained bands were evident. The reported modifications are quite similar to those described in the membranes of in vivo and in vitro aged red cells.

Amino Acids↗
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

Reduction of DABS-L-methionine-dl-sulfoxide by protein methionine sulfoxide reductase from polymorphonuclear leukocytes: stereospecificity towards the l-sulfoxide.

A new synthetic substrate for protein methionine sulfoxide reductase is proposed. We show that extracts from human polymorphonuclear leukocytes can reduce 4-dimethylaminoazobenzene-4'-sulfonyl-L-methionine-dl-sulfoxide [DABS-L-Met-dl-(O)] to the corresponding methionine derivative, in the presence of dithiothreitol or dithioerythritol. The product of the reaction (DABS-Met) was separated by reversed-phase HPLC and detected by reading the absorbance at 436 nm. Due to the chirality of the sulfur atom in the sulfoxide, two diastereomers of Met(O) exist, namely Met-l-sulfoxide and Met-d-sulfoxide. After separation of the two forms and preparation of the DABS-derivatives, we observed a preferential reduction of the l-sulfoxide by polymorphonuclear leukocytes extracts. We discuss the possibility that the observed stereospecificity might have physiological relevance in the field of the oxidative modifications of proteins.

Azo Compounds↗