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P Demuro

Publications and source records attributed to P Demuro.

17 recordsLinked to original sources
PubMed1994

Modifications of low density lipoprotein induced by the interaction with human plasma glycosaminoglycan-protein complexes.

Glycosaminoglycan (GAG)-protein complexes from human plasma were separated into low charge (LC-GP) and high charge (HC-GP) components. LC-GP and HC-GP differed with respect to GAG and protein composition and to molecular size. The in vitro interaction of both GAG-protein complexes with human LDL was investigated. LC-GP did not precipitate LDL. On the contrary, HC-GP formed insoluble complexes with LDL, following a biphasic behaviour on increasing HC-GP concentration. In the presence of a HC-GP/LDL ratio higher than 0.02 the interaction stoichiometry was shifted towards the formation of soluble complexes. Papain treatment of HC-GP completely prevented LDL precipitation. Moreover, the extent of HC-GP-induced precipitation of LDL was markedly reduced by the simultaneous addition of LC-GP. Data obtained with standard GAGs showed that heparin (HE) and chondroitin-6-sulphate (C6S) were the most effective ligands in precipitating LDL. However, the shape of precipitation curves was markedly different. C6S behaved similarly to HC-GP, suggesting that GAG chains could play an important role in insoluble complex formation with LDL. Steady-state fluorescence anisotropy investigation indicated that HC-GP induced a significant decrease in the microviscosity of LDL hydrophobic region. This effect was no longer detectable after either addition of LC-GP or papain treatment of HC-GP. Differential scanning calorimetry (DSC) demonstrated that both lipid and protein components of LDL were affected by the interaction with HC-GP. The temperature of irreversible thermal unfolding of apo B100 was shifted to a lower value and a second peak appeared in the region of the reversible melting of cholesterol esters. Both the fluorescence anisotropy and the DSC data obtained with standard HE and C6S indicated that GAG chains were directly involved in affecting physico-chemical properties of complexed LDL. These results suggest that the interaction with plasma HC-GP could modify LDL structural properties. However, LC-GP is likely to act as a modulator, probably preventing the interaction between HC-GP and circulating LDL.

Blood Proteins↗
PubMed1992

[Characterization of plasma glycosaminoglycans in hemodialysis patients].

Glycosaminoglycans are heteropolysaccharides composed of disaccharide repeating subunits, each one containing a uronic acid component (glucuronic or iduronic acid) and a hexosamine (N-acetyl-glucosamine or N-acetyl-galactosamine, which may be differently sulphated). The presence of GAGs in human plasma has been demonstrated in several studies; they are bound to plasma proteins through non-covalent linkages. However, very little is known about either their origin or their physiological role. Due to their anionic charge, they may influence some metabolic processes, such as blood coagulation, and they could also have a role in urolithiasis and atherogenesis. Moreover, they may be important in modulating the metabolism of some lipoproteins by affecting the rate of their catabolism. Modifications of GAG pattern have been described in a few pathological conditions such as mucopolysaccharidosis, connective tissue diseases and kidney diseases. A high frequency of accelerated atherosclerosis has been observed in haemodialysis patients (HD), probably associated with the altered lipoprotein profile, which is often described in these subjects. Since GAGs may play a role in lipoprotein metabolism, we isolated and characterized plasma GAGs from a group of HD patients and a group of normal matched subjects. Quantitative analysis of plasma GAGs showed a significant increase of these polysaccharides in the HD group. Circulating levels of GAGs were 8.21 +/- 1.89 micrograms/ml in control subjects, and 15.08 +/- 3.13 micrograms/ml in the HD group (p < 0.0001). The isolation of plasma GAGs by ion-exchange chromatography produced two uronic acid containing families: a low-charge (peak I) and a high-charge (peak II) species. Both of these contained GAGs associated with plasma proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, DEAE-Cellulose↗
PubMed1990

Structural and functional modifications of human aorta proteoglycans in atherosclerosis.

Proteoglycans (PGs) were extracted from minced normal human aorta intima and media and adjacent atherosclerotic plaques. Samples obtained from each individual artery which showed different degrees of atherosclerotic involvement were studied separately. Comparing normal and atherosclerotic areas from the same aorta, the hexuronic acid content was always lower in the atherosclerotic minces. Atherosclerotic samples always contained a higher percentage amount of chondroitinase AC resistant material. PGs were sequentially extracted with increasing guanidine hydrochloride (GuHCl) concentrations. 0.4 M GuHCl extracted about 13% of total PGs, containing mostly chondroitin sulphate (CS), whilst 4 M GuHCl extracted about 50% of total PGs, containing CS, dermatan sulphate (DS), heparan sulphate and hyaluronic acid. PGs from atherosclerotic minces showed a higher DS amount, based on electrophoretic glycosaminoglycan (GAG) analysis. PGs extracted with 4 M GuHCl were further characterized by gel-chromatography and by CsCl density gradient centrifugation. The relative content of PGs with highest hydrodynamic size appeared to be markedly reduced in all the atherosclerotic samples. LDL/GAGs and LDL/PGs interactions were studied by affinity chromatography. GAGs obtained by papain digestion of PGs extracted from atherosclerotic areas contained a glycosaminoglycuronan interacting more strongly with human LDL than GAGs from normal areas of the same artery. The complete elution of PGs required higher NaCl concentration than GAGs. Moreover, PGs from atherosclerotic samples showed higher affinity for LDL than PGs from normal areas of the same aorta.

Aged↗
PubMed1988

Hb G-Philadelphia, or [alpha 68(E17)Asn----Lys], in north Sardinia: detection by isoelectric focusing and identification by HPLC of tryptic peptides.

11,129 individuals of the northern area of the island of Sardinia (7,717 newborns and 3,412 adults) were examined for the Hb G-Philadelphia variant [alpha 68(E17)Asn----Lys]. Hemolysates were analysed by isoelectric focusing, and the variant identified by reversed phase high performance liquid chromatography of tryptic peptides. A total of seven heterozygotes (1 in 1,589) were identified. This is probably the highest prevalence of this mutant so far described. Percentages of the variant (average 35.1 +/- 6.2%) were trimodally distributed with modes centering on 28, 36, and 42%, respectively. These values suggest that the G-Philadelphia allele occurs in Sardinians both on a single and on a double locus chromosome. The linkage with alpha-thalassemia may be the reason for the high frequency of the variant.

Adult↗
PubMed1986

DNA polymorphisms in North Sardinian newborns and their linkage with abnormal gamma globin gene arrangements and with beta (0) -thalassemia.

Fetal hemoglobin analysis and globin gene mapping have identified one type of beta(0)-thalassemia and four different gamma globin gene arrangements among newborn babies from the northern part of Sardinia. The beta(0)-thalassemia with a nonsense mutation at codon 39 was found on two chromosomes, each with a distinct pattern of polymorphic restriction sites; one had the A gamma T (A gamma 75 Ile----Thr) mutation, while the second did not. Four closely related haplotypes were identified for chromosomes with the A gamma T mutation. The gamma-thalassemia heterozygosity with the -GA gamma- hybrid gene fell into two categories. One apparently originated through crossing-over between mismatched chromosomes characterized by the most common haplotype, while the other had polymorphisms resembling those of a less frequently occurring chromosome. Chromosomes with the -G gamma-AG gamma-A gamma- triplication had polymorphic sites to be expected for this condition, being complimentary to the -GA gamma- thalassemias. Of the two additional gamma globin gene variations the -G gamma- G gamma- arrangement was associated with the chromosome with the most commonly occurring haplotype, while the chromosome with the -A gamma-A gamma- arrangement had a haplotype characteristic for that with the A gamma T mutation, which identified an -A gamma-A gamma T- arrangement. The incidental discovery of a silent beta-chain mutant, Hb Hamilton, with the Val----Ile substitution at position beta 11, in five newborns was also reported.

Chromosome Mapping↗
PubMed1986

Polymorphism of foetal haemoglobin in the Sardinian beta +-thalassaemia.

12 thalassaemic patients from Northern Sardinia showing the beta + phenotype were examined by isoelectric focusing and high-performance liquid chromatography techniques for the determination of the variant A gamma T globin chain of the foetal haemoglobin. Two patients (16.7%) were homozygotes for the A gamma T gene variant, 2 (16.7%) were heterozygotes and 8 (66.7%) were homozygotes for the normal A gamma I allele. The A gamma T gene frequency was 0.183, much lower than the observed 0.823 in beta zero homozygosity. These data suggest the presence of at least 2 beta +-thalassaemic chromosomes in Sardinians, one associated with the variant A gamma T allele and one associated with the normal A gamma I. The latter is prevalent among adult patients showing the intermediate form of the thalassaemic disease, which is not transfusion-dependent.

Adolescent↗
PubMed1986

The gamma globin chain heterogeneity of the Sardinian newborn baby.

The hemoglobin of 2048 newborn babies from Sardinia was analyzed by isoelectric focusing and polyacrylamide gel electrophoresis in order to determine the level of Hb F-Sardinia (with A gamma T) and the G gamma chain. Hb F-Sardinia values of 15.5 +/- 2.6% were present in the A gamma T heterozygote whereas 30.7 +/- 5.2% were present in the homozygote. The A gamma T gene frequency was 0.17. Most of the babies tested showed the normal G gamma level either in the absence of the A gamma T anomaly (69.6 +/- 4.1%), or in the presence of the anomaly in both the heterozygous state (70.9 +/- 4.8%) and the homozygous state (71.1 +/- 3.4%). Similar values were shown in nine homozygotes for beta-thalassemia discovered during the screening. Nine newborn babies (0.44%) showed particularly low G gamma levels (38.3 +/- 6.8%) whereas 18 newborn babies showed high G gamma levels (83.9 +/- 2.6%). The frequencies of the anomalies (0.0022 for the low G gamma and 0.0044 for the high G gamma) were the lowest observed in Caucasian and other ethnic groups. Data suggest the presence of abnormal gamma globin gene arrangements in the Sardinian population.

Electrophoresis, Polyacrylamide Gel↗
PubMed1981

[Applicability of cellulose acetate electrophoresis of globin chains to thalassemia screening].

We considered the possible application of globin chain separation on cellulose acetate strips electrophoresis to thalassemia screening. The method shows good accuracy and reproducibility when compared with the chromatographic method on CM-cellulose. The electrophoretic method could be recommended as the simplest test of hemoglobin biosynthesis in countries where high incidence of thalassemic syndromes occurs.

Chromatography, Ion Exchange↗
PubMedDate not supplied

LDL interaction with proteoglycans isolated from human aortas with different atherosclerotic involvement.

BACKGROUND: Proteoglycan (PG)-LDL interaction is likely to be involved in lipid deposition in arterial wall. The relative content and the structural properties of different PG populations change in human aorta with atherosclerotic degeneration. Therefore, we extracted and separated these PGs from human aorta samples with increasing severity of atherosclerotic involvement and studied their interactions with human LDL. MATERIALS AND METHODS: PGs were extracted with 6 M urea, purified by ion-exchange chromatography and separated into two different populations (PGI and PGII) on the basis of hydrodynamic size and glycosaminoglycan composition. The interaction of both PGI and PGII with LDL was studied separately by precipitation assay. RESULTS: The ratio PGI/PGII decreased markedly with increasing severity of the disease. Both PGI and PGII formed insoluble complexes with LDL. However, the shape of saturation curves was markedly different. An excess of PGI from normal or intermediately affected aorta inhibited insoluble complex formation with LDL. On the contrary, an excess either of PGII or of PGI from severely affected aorta did not inhibit insoluble complex formation. In the case of PGII, the maximum of percentage cholesterol precipitated was higher when PGII from severely affected aorta was used. CONCLUSIONS: The different interactions of LDL with either PGI or PGII are likely to depend on the different structural properties of PGs. The decrease of PGI/PGII ratio following atherosclerotic degeneration could play an important role in lipid deposition in arterial wall.

Adult↗