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S B Etcheverry

Publications and source records attributed to S B Etcheverry.

27 records · Page 2Linked to original sources
PubMed1996

A spectroscopic study of the interaction of the VO2+ cation with the two components of chondroitin sulfate.

The interaction of the vanadyl (IV) cation with N-acetyl-D-galactosamine, D-galactosamine, and D-glucuronic acid has been investigated by electron absorption spectroscopy at different metal to ligand ratios and pH values. In the case of D-glucuronic acid, a more detailed study was undertaken, using differential IR spectroscopy in solution. The results show that the cation interacts with the two nitrogenated molecules only at higher pH values, generating 2:1 ligand to metal complexes in which coordination occurs through two pairs of deprotonated OH groups of the rings. In the case of D-glucuronic acid, the IR-measurements allowed a wider insight into the structural characteristics of the complexes generated in acidic media. The involvement of the glycosidic oxygen atom in coordination, is suggested at pH = 3.

Acetylgalactosamine↗
PubMed1996

A spectrophotometric study of the interaction of VO2+ with cytosine in nucleotides.

The interaction of VO2+ with cytidine-monophosphate, -diphosphate, and -triphosphate has been investigated at different pH values and metal-to-ligand ratios by differential UV-absorption spectroscopy. It is shown that at pH values between 3 and 5 and for metal-to-ligand ratios up to 0.5, the cytosine ring is involved in coordination. On the other hand, measurements performed at pH = 7 show the absence of this type of interaction. Some comments on the possible structural characteristics of the generated complexes are made on the basis of the known coordination behavior of cytosine. Similar spectroscopic measurements with the systems VO2+/PO(3-)4, VO2+/P2O(4-)7, and VO2+/D-ribose were also performed in order to complement the analysis of the experimental results.

Cytosine↗
PubMed1995

Vanadium derivatives act as growth factor--mimetic compounds upon differentiation and proliferation of osteoblast-like UMR106 cells.

The effect of different vanadium compounds on proliferation and differentiation was examined in osteoblast-like UMR106 cells. Vanadate increased the cell growth in a biphasic manner, the higher doses inhibiting cell progression. Vanadyl stimulated cell proliferation in a dose-responsive manner. Similar to vanadate, pervanadate increased osteoblast-like cell proliferation in a biphasic manner but no inhibition of growth was observed. Vanadyl and pervanadate were stronger stimulators of cell growth than vanadate. Only vanadate was able to regulate the cell differentiation as measured by cell alkaline phosphatase activity. These results suggest that vanadium derivatives behave like growth factors on osteoblast-like cells and are potential pharmacological tools in the control of cell growth.

Animals↗
PubMed1995

Spectroscopic, magnetic, and electrochemical behavior of the copper(II) complex of carnosine.

Different physicochemical studies were undertaken with polycrystalline samples of the complex [Cu2(carnosine)2(H2O)2].2H2O. The infrared spectrum was discussed in comparison with that of free carnosine and on the basis of the known structural data. Magnetic susceptibility measurements were performed between 4.2 and 300 K, showing an effective magnetic moment of 1.79 BM. Both the electronic (reflectance) and ESR spectra were compatible with the existence of a dx2-y2 ground state. The axial reversed ESR spectrum could be explained on the basis of a very weak interdimeric coupling mechanism. The electrochemical behavior, investigated by cyclic voltammetry, shows that the complex possesses a very high redox stability. The possible SOD-like activity was tested using the NBT/superoxide reduction assay. The results show a negligible SOD activity.

Carnosine↗
PubMed1994

Vanadium compounds. Their action on alkaline phosphatase activity.

The direct effect of different vanadium compounds upon alkaline phosphatase (ALP) activity was investigated. Vanadate and vanadyl inhibited both the soluble and particulate ALP activity from UMR.106 cells and from bovine intestinal ALP. We have also shown the inhibition of ALP activity in the soluble fraction of osteoblasts by peroxo and hydroperoxo vanadium compounds. ALP activity in the particulate fraction was not inhibited by these species; nor was the bovine intestinal ALP. Using inhibitors of Tyr-phosphatase (PTPases), the soluble ALP was partially characterized as a PTPase. The major activity in the particulate fraction represents the bone-specific ALP-activity. This study demonstrates that different forms of vanadium are direct inhibitors of ALP activity. This effect is dependent on the enzymatic activity investigated and on the origin of the ALP.

Alkaline Phosphatase↗
PubMed1994

The interaction of the vanadyl (IV) cation with chondroitin sulfate A.

The interaction of VO2+ with the muchopolysaccharide chondroitin sulfate A (CSA) has been investigated by electron absorption spectroscopy and infrared measurements in aqueous solutions at different pH-values and ligand to metal ratios up to 6:1. The generation of a VO(CSA)2 species could be demonstrated. Coordination of the oxocation through the carboxylate group and the glycosidic oxygen of the D-glucuronate moieties is suggested. Infrared spectra of some poorly characterized solid VO/CSA complexes point to the same bonding characteristics. Preliminary results obtained at higher ligand to metal ratios suggest a different coordination behavior.

Carbohydrate Conformation↗
PubMed1984

A model study of the incorporation of vanadium in bone.

A study of mixed apatites of the type Ca10 (PO4)6-X( VO4 )X(OH)2 has been undertaken in order to obtain an insight into the structural consequences of the incorporation of vanadium in the inorganic phase of bone. The crystallographic analysis as well as the vibrational spectra of these "models," show that low or moderate VO43 - concentration does not produce any lattice distortion and has little effect on the strength of the P-O and O-H bonds. This study has also shown that the incorporation of VO43 - ions in the Ca10 (PO4)6(OH)2 matrix at low temperatures is only possible if the hydroxyapatite is in the amorphous state.

Bone and Bones↗