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Biomedical subjects

G Zanaboni

Publications and source records attributed to G Zanaboni.

32 records · Page 2Linked to original sources
PubMed1991

[Standardization of bone tissue densitometry].

Traditional X-ray technique have proved be scarcely reliable in determining bone tissue mineral status especially when comparing X-rays made at different times. The use of ergal or hydroxylapatite samples has been put forward to resolve this problem since, when used together with computerised imaging techniques, they allow a more precise and quantitative analysis to be made. The velidity of tyhis technique is confirmed by an experimental trial on animal bone.

Absorptiometry, Photon↗
PubMed1991

Ultrastructural studies on dermis from prolidase deficient subjects.

Ultrastructural analyses were performed on clinically normal skin from forearm and/or femoral regions of five subjects, all excreting high levels of gly-pro dipeptides into the urine and exhibiting very low prolidase activity on hemolyzed erythrocytes. In both regions, the overall organization of the dermis was normal. Stereological analysis, however, showed that collagen volume density was reduced when compared to that of age-matched controls. Collagen fibrils did not show ultrastructural alterations, but they were distributed into a higher number of small bundles, and their diameters shifted towards lower values compared to age-matched controls. The elastin volume density was slightly reduced in the patients, especially in the femoral areas. In both forearm and femoral dermis, elastin fibers were significantly more numerous and smaller than in controls. Furthermore, elastin fibers were apparently normal in the forearm dermis, whereas appeared polymorphic and cribriform in the femoral skin. The results focused on the importance of efficient proline re-utilization for normal collagen and elastin synthesis and deposition. The differences between femoral and forearm skin regions from both clinical and ultrastructural points of view, may depend on mechanisms that regulate circulation and, possibly, on other factors which modulate the phenotypic expression of mesenchymal cells.

Adult↗
PubMed1989

Low levels of serum type III procollagen aminoterminal propeptide confirmed type III collagen deficiency in patients without typical clinical symptoms of Ehlers-Danlos type IV.

Biochemical analysis of skin samples revealed that the content of type III collagen was greatly reduced in several subjects with joint hypermobility, stretchability and bruisability of skin. When cultured dermal fibroblasts were found to secrete decreased amounts of type III procollagen into medium (about 30-45% the normal amount) and serum type III procollagen aminopropeptide levels were significantly lower than normal values (P less than 0.001). The abnormalities in type III procollagen are in keeping with Ehlers-Danlos type IV although the clinical findings in our patients are not normally associated with this disorder. The results illustrate the clinical heterogeneity of Ehlers-Danlos type IV and the importance of biochemical analysis, such as determination of type III procollagen aminopropeptide levels, to check type III collagen metabolism especially if there is no family history and if correct diagnosis is not reliable by clinical examination alone.

Child↗
PubMed1988

Asymmetric Marfan syndrome.

We describe a girl with Marfan syndrome in whom the clinical expression of the disease was much more evident on the left side of the body.

Child, Preschool↗
PubMed1987

Collagen glycosylation in human granulation tissue and scar.

Some biochemical characteristics of collagen extracted from granulation tissue were studied and compared with those of normal skin and scar. By using electrophoretic techniques the type III collagen content was confirmed to be significantly greater in granulation tissue and lower in scar with respect to normal skin. The chromatographic determination of hydroxylysine (Hyl) glycosides in collagen extracted from granulation tissue showed a significant increase in both the degree of Hyl glycosylation and in the di-/monoglycoside ratio, while both parameters turned out to be lower in scar. These data suggest that the degree of Hyl glycosylation and the di-/monoglycoside ratio could represent an index of the degree of collagen fiber maturation.

Cicatrix↗
PubMed1983

Biochemical investigations of different forms of osteogenesis imperfecta. Evaluation of 44 cases.

Forty-four patients with Osteogenesis Imperfecta (O.I.) were divided into groups on the basis of clinical and genetic criteria and the alterations in collagen and glycosaminoglycans (GAG) in the subjects of each group were examined. The largest group of patients as affected with a mild form of O.I. and showed an increased ratio of type III to type I collagen in skin and an increase of the ratio of hydroxylysine diglycoside to monoglycoside in skin collagen. The group of patients affected with a severe nonlethal form of O.I. appeared to be heterogeneous both from a clinical and from a biochemical point of view. A marked increase of the diglycoside to monoglycoside ratio was observed in skin and urine, whereas the ratio of type III to type I collagen in skin was within the normal range or significantly decreased. Some of these patients also showed alterations involving proteoglycans, e.g. in urinary GAGs a decreased galactosamine to glucosamine ratio could be demonstrated. Similar and more marked alterations involving both collagen and GAG metabolism were observed in five children affected with a lethal form of O.I.

Collagen↗
PubMed1982

Biochemical and morphological modifications in rabbit Achilles tendon during maturation and ageing.

1. Achilles tendons of foetal, newborn, adult and old rabbits were examined by electron microscopy after staining by conventional methods or with the periodate/silver/methenamine technique. 2. The mean diameter of collagen fibrils increased with age whereas silver/methenamine-positivity became less evident. 3. Biochemical analyses showed a great decrease of the concentration of glycoproteins and galactosamine-containing glycosaminoglycans. 4. Collagen content increased with maturation and ageing of the tissue. 5. The extent of glycosylation of collagen hydroxylysine residues was also age-dependent; the total amount of hydroxylysyl glycosides rapidly decreased in the last days of prenatal life and in the first months after birth, corresponding to the rapid growth in collagen fibre diameter. 6. The hydroxylysyl diglycoside concentration decreased more markedly than that of the monoglycoside, thus indicating a possible gradual removal of the monosaccharide units. A role for the extent of glycosylation of tropocollagen molecules in fibre organization was suggested.

Achilles Tendon↗
PubMedDate not supplied

Prolidase deficiency: biochemical study of erythrocyte and skin fibroblast prolidase activity in Italian patients.

BACKGROUND AND METHODS: Prolidase deficiency (PD), a rare, autosomally inherited disorder causing iminodipeptiduria is associated with a number of clinical manifestations, the principle feature being chronic skin ulceration. The enzyme prolidase cleaves iminodipeptides containing C-terminal prolyl or hydroxyprolyl residues and is important in the final stages of protein catabolism. We report clinical and biochemical findings in 8 Italian patients with proven prolidase deficiency. There was considerable heterogeneity in age at onset of symptoms (varying from 3-17 years), mental retardation and clinical manifestations (asymptomless to very severe). Prolidase activity was determined in hemolysates of patient erythrocytes and cultured dermal fibroblasts. RESULTS: Prolidase activity was found to be deficient, especially against gly-pro. Erythrocyte and fibroblast enzyme was also separated into two forms, a major isoform (I) and a minor one (II) by fast protein liquid chromatography, and activity against different iminodipeptide substrates was tested. Isoform I activity was markedly reduced in all patients as compared to normal controls, while isoform II activity appeared to be unaltered. CONCLUSIONS: We were unable to find any correlation between degree of enzyme activity loss and severity of symptoms.

Adolescent↗
PubMedDate not supplied

Effect of the triterpenoid fraction of Centella asiatica on macromolecules of the connective matrix in human skin fibroblast cultures.

The mechanism of action of the total triterpenoid fraction extracted from Centella Asiatica (TTFCA) was evaluated using human skin fibroblasts cultures as the experimental system. In particular its influence on the biosynthesis of collagen, fibronectin and proteoglycans was considered. The presence of TTFCA (25 micrograms/ml) does not seem to affect cell proliferation, total protein synthesis or the biosynthesis of proteoglycans in a significant way. A statistically important increase was observed in the percentage of collagen and, as revealed by immunofluorescence measurements, in cell layer fibronectin. This effect on collagen and fibronectin may help to explain the action of TTFCA in promoting wound healing, and suggests an interesting working hypothesis for its action on basal endothelia.

Cell Survival↗
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

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↗