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S Paoletti

Publications and source records attributed to S Paoletti.

18 recordsLinked to original sources
PubMed1992

Elemental analysis of growth plate cartilage by synchrotron-radiation-induced X-ray emission (SRIXE).

The elemental composition of growth plate cartilage from calf scapula has been studied by means of SRIXE. X-ray emission spectra were obtained from the resting, hypertrophic and calcified regions of cartilage; then, each element was mapped with a lateral definition of about 10 microns x 10 microns. Evidence was found for a homogeneous distribution of the elements in resting cartilage compared to changes in local concentration of some atoms in the hypertrophic-calcified tissue. In this zone Ca, Sr, Ni, Zn, S, reach the maximal concentration at the calcification front while Cu shows a uniform distribution. A Zn distribution similar to that of the Zn-containing enzyme alkaline phosphatase, the key enzyme of calcification, is found.

Animals↗
PubMed1992

1H- and 13C-NMR studies of solutions of hyaluronic acid esters and salts in methyl sulfoxide: comparison of hydrogen-bond patterns and conformational behaviour.

The 1H- and 13C-NMR spectra of the ethyl and benzyl esters and the tetrabutylammonium and tetraethylammonium salts of hyaluronic acid [[symbol: see text]2)-beta-D-GcpA+-1----3)-beta-D-GlcpNAc-(1[symbol: see text]n] in Me2SO-d6 have been assigned using 1D and 2D techniques. The chemical shifts of the resonance of GlcNAc C-3 suggest that the relative orientations of the monosaccharides at the (1----3) linkage in the esters and salts are different. Small differences in the chemical shifts of the resonance GlcA C-4 suggest only a slight conformational variation around the (1----4) linkage. The 13C-NMR data also suggest similarities in conformation between the esters in Me2SO-d6 and the salts in water. The chemical shifts of the 1H resonances for NH and OH groups and their temperature dependence for the esters and salts in Me2SO reveal markedly stronger inter-residue hydrogen bonds between the carboxyl and NH groups and between HO-4 of GlcA and O-5 of GlcNAc for the salts. The 3J2,NH values indicate a slightly different orientation for the acetamido group. For solutions in Me2SO, the higher segmental flexibility of the esters is supported by the line widths, whereas the reduced viscosity for the tetrabutylammonium salt showed a sigmoidal concentration dependence and suggests association of chains which could contribute to the segmental rigidity. The linear concentration dependence for the benzyl ester suggests a higher overall flexibility without chain association.

Carbohydrate Conformation↗
PubMed1992

31P NMR studies of resting zone cartilage from growth plate.

31P NMR of superfused resting cartilage demonstrated the presence of phosphocreatine in chondrocytes. Changes in pH and in the NTP level were followed during carbon source starvation. From 31P spectra of perchloric acid extracts, phosphoethanolamine, phosphocholine, and the corresponding glycerol diesters were identified as the major phosphomonoester and phosphodiester components.

Animals↗
PubMed1991

Energy state of chondrocytes assessed by 31P-NMR studies of preosseous cartilage.

The energy state of resting and hypertrophic chondrocytes from growth plate was studied by 31P-NMR spectroscopy of superfused cartilage slices. The presence of phosphocreatine was demonstrated in both cell types, using a repetition time of 3 s. By comparing the decline in the nucleoside triphosphate level after adding blockers of the glycolysis or of the mitochondrial respiration, it was deduced that resting and hypertrophic chondrocytes use both metabolic pathways for energy production, but the glycolysis dominates. Hypertrophic cells rely more on the mitochondrial respiration than the resting cells.

Animals↗
PubMed1991

1H-NMR studies of lipid extracts of rat liver mitochondria.

Lipid extracts of rat liver mitochondria were studied by 1H-NMR at 200 MHz. Each spectrum, obtained in 6 min with routine acquisition parameters, allowed the estimation of the phosphatidylcholine/phosphatidylethanolamine ratio, the cholesterol/total lipid molar ratio, the average fatty acid length, the unsaturation ratio and the oxidation state of the ubiquinone/ubiquinol couple. 1H-NMR spectroscopy was also used to analyze structural changes of the lipids following peroxidation. In model liposomes subjected to enzymatic peroxidation the appearance of hydroperoxides and conjugated double bonds were detected, whereas in mitochondria no such changes were seen even after a period of relatively high oxidative stress. This suggests that the systems for protection against oxidative damage in mitochondria are able to keep the amount of peroxidation products below the detection limit of the technique.

Animals↗
PubMed1990

Ruthenium red complexation with ionic polysaccharides in dilute aqueous solutions: chirooptical evidence of stereospecific interaction.

This paper presents optical and chirooptical data on the interaction of the microscopy-staining agent ruthenium red with carboxylated polysaccharides in dilute aqueous solution. The polysaccharides used are both natural (alginate and pectate) and semisynthetic (C6-oxidized cellulose and C6-oxidized amylose). A preliminary discussion of the molecular structure and conformational features which control the interaction is presented.

Alginates↗
PubMed1990

Thermodynamics of the proton dissociation of natural polyuronic acids.

The thermodynamic properties of the dissociation of natural polyuronic acids in dilute aqueous solution at 25 degrees C are reported. The investigation concerns polygalacturonic acid and alginic acids from different sources, including highly homogeneous mannuronic and gulronic fractions and involved potentiometry, isothermal calorimetry, dilatometry and circular dichroism measurements. The dissociation of polyuronic acids was studied as a function of degree of dissociation, concentration of the polymer and ionic strength. Abnormal behavior upon dissociation was observed only in polyguluronic and polygalacturonic acids and attributed to a pH-induced conformational transition and/or to an interchain disaggregation. Direct molecular weight evidence supports the proposed intramolecular transition of polygalacturonate chain.

Alginates↗
PubMed1989

Polyelectrolytic effects in semi-flexible carboxylate polysaccharides. Part 2.

A statistical model is presented in which an ionic polymer is taken as a linear arrangement of flexible segments (similar to the spring-bead model). This model is used to represent semi-flexible linear ionic polysaccharides in solution. The distribution of end-to-end distances is taken from Monte Carlo calculations of the amylosic chain conformation and combined with Manning's counterion condensation theory of linear polyelectrolytes. The excess thermodynamic properties are then calculated as a function of the degree of ionization and of a number of physical variables. The results show that the statistical average of thermodynamic functions taken over the conformational states is not equivalent to the thermodynamic function of the average conformation. This has important implications for the correct comparison of theoretical prediction with the experimental results.

Carbohydrate Conformation↗
PubMed1989

Conformational transition of poly(alpha-L-glutamic acid). A polyelectrolytic approach.

The charge-induced conformational transition of poly(alpha-L-glutamic acid) (PLGA) is considered in this paper from the point of view of proton dissociation. Equations for the excess electrostatic Gibbs energy of dissociation (i.e., delta pKa) are derived as a function of the degree of ionization, alpha. These analytical equations are used to describe some experimental dissociation curves at different polymer and salt concentrations. The dependence of the calculated delta pKa with respect to the ionic strength for the two conformational states, alpha-helical and extended coil, respectively, is rather satisfactorily explained. Even more interesting are the predictions which are derived from this approach for the transition point, alpha tr which is found to be ionic-strength dependent, in full agreement with the experimental results.

Kinetics↗
PubMed1987

[The blood coagulation system in progressive systemic scleroderma].

Twenty-five scleroderma patients have been studied to evaluate blood coagulative and fibrinolytic parameters. An increase in FVIII related activities and a reduction in fibrinolytic activity was observed. These changes may be related to the endothelial damage present scleroderma patients I the consequent "in loco" activation of blood coagulation may cause the microthrombosis that is very often observed in the earliest phases of the disease.

Adult↗
PubMed1987

Pulmonary involvement in progressive systemic sclerosis: a multidisciplinary approach.

In an attempt to define the early features and the natural evolution of lung involvement in progressive systemic sclerosis (PSS), we planned a multidisciplinary study of these patients using radiological, scintigraphic and functional methods. As yet we have studied 21 subjects, all affected by PSS according to the American Rheumatism Association criteria. A well-defined restrictive functional pattern was present only in 10 patients out of 21; an increased elastic recoil may be present before a significant decrease of the transfer test for carbon monoxide; an increased alveolar-capillary permeability assessed by the 99mTc-diethylene-triamine-pentacetic acid (99mTc-DTPA) clearance rate has been detected in almost all the patients (13 out of 14) in at least one lung field; no significant correlation has been found between the radiological lung involvement and the 99mTc-DTPA clearance rate. We think that these preliminary results are consistent with an alveolar and interstitial inflammation rather than with a vasculitic process.

Adult↗
PubMed1985

Serum beta 2-microglobulin in systemic sclerosis.

The role of beta 2 microglobulin (beta 2-m) in Systemic Sclerosis (SS) has been evaluated. Twenty-four female patients have been examined: 15 of them were affected by acrosclerosis (Group 1) and 9 of them by diffuse sclerosis (Group 2). 46.6% of Group 1 and 44.4% of Group 2 had values significantly higher than normal controls. (P less than 0.01 and P less than 0.005 respectively). The authors deal with the validity of the use of B2-m as index of inflammatory activity of the disease.

Adult↗
PubMedDate not supplied

An evaluation of some inflammatory, coagulative and immune factors in progressive systemic sclerosis.

Thirty-five patients affected by Progressive System Sclerosis (PSS) (20 acrosclerosis and 15 diffuse sclerosis) were subjected to the following laboratory tests: Beta 2 microglobulin (B2m), Fibronectin, C3c, C4, Fibrinogen, Factor VIII Coagulant (F. VIII:C), Factor VIII related Antigen (F. VIII:Ag), IgG, ESR, Antithrombin III (AT III), alpha 1 Antitrypsin (alpha 1AT) and alpha 2 Macroglobulin (alpha 2M). The results showed that no difference was observed between the normal group and the groups of PSS patients with respect to alpha 1AT, alpha 2M, and AT III. In contrast the B2m, ESR, IgG, F. VIII:Ag results were significantly higher in the PSS patients, while Fibrinogen and C3c results were slightly higher, but no high enough to be of statistical significance. The two PSS patient subgroups did not produce significant results, only the C4 values were lower in the Diffuse Sclerosis subgroup. From these results it seem that the tests used are not very useful indifferentiating the two subgroups of the PSS patients.

Adult↗
PubMedDate not supplied

Factor VIII complex in progressive systemic sclerosis.

Factor VIII complex and its related activities (Coagulant, Antigen and Ristocetin Cofactor) have been investigated in 23 patients with Progressive Systemic Sclerosis (PSS) divided into two groups: acrosclerosis and diffuse sclerosis. All Factor VIII-related activities were higher in PSS patients than in normal subjects. No difference in F. VIII-related Antigen (F. VIIIR:Ag), F. VIII-related Ristocetin Cofactor (F. VIIIR:Co) and F. VIII Coagulant activity (F. VIII:C) was found comparing the patient groups. F. VIII:C was increased significantly less than F. VIIIR:Ag and F. VIIIR:Co in both patient groups. Some hypotheses about the pathogenesis of this increase are discussed.

Adult↗