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Biomedical subjects

S Sestini

Publications and source records attributed to S Sestini.

49 records · Page 3Linked to original sources
PubMed1986

[Pyridine metabolism of the human erythrocyte].

Pyridine nucleotides are required for human erythrocyte survival, for their role in both glycolysis and pentose phosphate pathway. Human red blood cells have been used for the study of some pyridine nucleotide cycle reactions, but the whole sequence in the erythrocyte has not yet been completely determined. In the present work, pyridine coenzyme synthesis interrelationships and degradation have been revised, both in general and regarding to human erythrocytes. These cells are lacking the de novo pathway, and utilize exogenous free bases, especially nicotinic acid, as NAD precursors. Nicotinamide utilization is discussed in view of its role in the salvage pathway. Available data on enzyme kinetic and regulation characteristics are reviewed.

Adenosine Diphosphate↗
PubMed1982

[Kinetic characteristics of microsomal NAD-glycohydrolase natural and solubilized with a non-ionic surface-active substance].

Microsomal rat spleen NAD-glycohydrolase was solubilized by Nonidet P40. The solubilized enzyme shows Nicotinamide inhibition and pH dependence at the same extent as unsolubilized microsomal one. It differs from the latter in having a higher affinity for NAD and NADP, and in showing two peaks, instead of one, on electrofocusing: the former with a pH 5 pI without any activity, the latter with a pH 4, 1 pI with a high NAD-ase activity.

Animals↗
PubMed1980

[Method for testing niacin bound activities in man].

In order to value the availability of niacin in man, it has been more suitable to test erythrocyte nicotinate-phosphoribosyltransferase and nicotinamide-phosphoribosyltransferase activities. These enzymes catalyze the production of Des-NMN and NMN from free bases. The radioactive compounds, produced from [14C] NAc and [14C] NAm, are isolated by a gel chromatography and counted in liquid scintillation. It has been observed that nicotinamide-phoshoribosyltransferase is scarcely active in human erythrocytes, while the nicotinate-phosphoribosyltransferase gives a good indication of niacin availability.

Carbon Radioisotopes↗
PubMedDate not supplied

Density increase and ageing of erythrocytes in stored blood.

An increase in the density of erythrocytes was observed after storage of whole blood for 30 days at 4 degrees C in either acid citrate-dextrose or citrate-phosphate-dextrose-adrenaline. Glucose-6-phosphate dehydrogenase activity in unfractionated red blood cell lysates did not vary with the storage time. Enzyme activity in the lighter fraction separated by density gradient centrifugation was higher than that in heavier fractions. The decline in glucose-6-phosphate dehydrogenase activity with density was less marked after storage of whole blood for 30 days. It is suggested that density modifications are not related to the ageing of erythrocytes and additional mechanisms may be involved.

Blood Specimen Collection↗
PubMedDate not supplied

Evaluation of biocompatibility of metallic dental materials in cell culture model.

Biocompatibility of metals for dental use was tested using a three-dimensional model consisting of oral keratinocytes cultured on de-epidermised sub-mucosa. The toxicity of orthodontic metallic wire and soldering material was assessed through parameters such as the morphology and growth rate of the keratinocytes, as well as by classical histology, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sharp composition of metallic wires and soldering materials was assessed by Auger Electron Spectroscopy (AES). The results of our experiment showed that the new model revealed inhibition of keratinocyte growth and stratification near soldering material, whereas mucosal cells were able to grow and layer out on dental wire. It is concluded that this experimental model, which simulates the oral environment, is useful for studying the effects of materials for dental use for its sensibility and reproducibility. Moreover it can provide morpho-functional information which cannot be achieved by traditional methods.

Cell Culture Techniques↗
PubMedDate not supplied

Interrelationship between adenine and pyridine nucleotide metabolism in human erythrocyte life span.

Adenyl and pyridine nucleotide production has been tested in the whole erythrocyte population and in cells of different age, separated by Percoll density gradient. Both the cellular nucleotide production from adenine and nicotinic acid and the related phosphoribosyltransferase activities show a decrease during cellular life span. Pyridine nucleotide production decay in intact cells parallels the NAPRT pattern, while APRT decrease during senescence is greater than cellular adenine nucleotide production decay.

Adenine Nucleotides↗
PubMedDate not supplied

Characterization of NAD-glycohydrolase in rat lymphoid organs.

Rat thymus and thymocytes possess an NAD-glycohydrolase activity lower than spleen and spleen lymphocytes. In all cases, the highest activity (50%) is bound to the nuclei, while that in the soluble fraction is higher (in percent) in the lymphocytes than in the whole organ. Considering that thymus and thymocytes are characterized by a soluble NAD-ase activity higher than in spleen and in spleen lymphocytes, and that lymphocytes in general have a greater soluble than microsomal activity, we interpret these findings are evidence that the soluble NAD-ase is due essentially to T lymphocytes, of which it represents a typical feature.

Animals↗