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Biomedical subjects

M Dachà

Publications and source records attributed to M Dachà.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

The age-dependent metabolic decline of the red blood cell.

The oxidative and non-oxidative utilization of glucose was evaluated in human erythrocytes of different ages, separated by density gradient ultracentrifugation. Young red blood cells are able to metabolize 2.5 times more glucose than old ones; on the other hand, the amount of glucose utilized via the hexose monophosphate shunt does not show any age dependence. Glucose metabolism evaluated during in vivo ageing of a rabbit red cell population shows results very similar to those obtained for human cells. Metabolic stimulation of glucose utilization by high phosphate in both young and old human red cells increases glucose utilization by 40%. In the same way young and old erythrocytes were able to increase the amount of glucose metabolized via the hexose monophosphate shunt when an oxidative stimulus (methylene blue) was introduced. Human erythrocytes of different age possess similar abilities to transport glucose so that an age-dependent defect in glucose transport can be excluded. The ATP content of human and rabbit red blood cells, as a function of cell age, follows the decrease in glucose metabolized via the Embden-Meyerhof pathway. Reduced glutathione, on the other hand, after a small decrease associated with the "maturation" of reticulocytes into red cells, remains constant like the rate of the hexose monophosphate shunt.

Adenosine Triphosphate↗
PubMedDate not supplied

The wall paintings in the Oratorio of San Giovanni Battista in Urbino: a study finalized to a correct conservation project.

The walls of the Oratorio of San Giovanni Battista in Urbino are decorated with outstanding mural paintings dating back to the 15th century. Due to degradation processes that have occurred in the past years, such paintings require a conservative restoration project. In order to evaluate reasons of the decay, some scientific studies have been performed. They consist of macroscopic observations and chemical (EDS), morphological (SEM) and mineralogical (XRD) analyses of samples both from the original preparatory layers under the painted layers and from the restored plasters at the surbase of the wall. In addition, environmental studies have been performed to verify microclimatic conditions of the church in which the mural paintings are located. Finally, a conservative restoration project was proposed.

Architecture↗
PubMedDate not supplied

Rhodiola rosea as antioxidant in red blood cells: ultrastructural and hemolytic behaviour.

Rhodiola rosea L. (Crassulaceae) is a plant that lives at high altitude in Europe and Asia, widely used for its high capacity to increase the organism resistance to different stress conditions. Although a few international literature supports these effects, today R. rosea has become a common component of many dietary supplements also in the Western world. The aim of the present study was to investigate the effect of the R. rosea roots aqueous extract on in vitro human erythrocytes exposed to hypochlorous acid (HOCl)-oxidative stress. Several damages occur in human erythrocytes exposed in vitro to HOCl, among these membrane protein and lipid modifications, shifting from the discocyte shape to the echinocyte one, and determining lysis ultimately. Therefore, in the present work, the evaluation of the antioxidant capacity of the Rhodiola extract has been carried out by means of scanning electron microscopy and of hemolytic behaviour on human erythrocytes exposed to HOCl in the presence of increasing doses of the aqueous extract in different experimental environments (co-incubation and subsequent incubations). The results obtained are consistent with a significant protection of the extract in presence of the oxidative agent, but a cautionary note emerges from the analysis of the data related to the cell exposition to the plant extract in the absence of any induced oxidative stress. In fact, the addition to erythrocyte of high doses of R. rosea extract always determines severe alterations of the cell shape.

Antioxidants↗
PubMedDate not supplied

Role of hexokinase in the regulation of glucose metabolism in human erythrocytes.

Red blood cell glucose metabolism was studied in erythrocytes from a patient with trisomy 10 p which resulted in + 50% hexokinase specific activity, in normal controls and in cases of heterozygous hexokinase deficiency. The results obtained show that the hexokinase activity level is an important factor in the control of the erythrocyte's glycolytic rate while having no appreciable effect on the hexose monophosphate pathway under resting conditions. No clear conclusion could be drawn when an oxidative stress was present.

Blood Glucose↗
PubMedDate not supplied

Purification and properties of the cytoplasmic hexokinase from rabbit brain.

About 90% of the total hexokinase activity in rabbit brain was found to be associated with mitochondria while the remaining part was found in the cytosolic fraction. The soluble enzyme was purified 4,700-fold to near homogeneity by a combination of ion-exchange chromatography, dye-ligand chromatography and affinity chromatography. The purified enzyme showed a specific activity of 110 units/mg of protein and was obtained in 70% yield. The molecular weight of the purified hexokinase was found to be approximately 98,000 both for the native and the denatured enzyme. The isoelectric point, pI, was 6.2 pH units by isoelectric focusing and the enzyme was found to be able to phosphorylate several hexoses. Mg . ATP2-, among the nucleotide substrates, was the most effective phosphate donor. The properties of the purified cytoplasmatic hexokinase were compared with those of the solubilized mitochondrial enzyme. No significant differences were found in molecular weight, isoelectric point, pH dependence of activity, electrophoretic mobility and affinity for glucose and Mg.ATP2-. However, the temperature dependence of activity, and the specificity for several hexose substrates were markedly different.

Animals↗
PubMedDate not supplied

Action of orthophosphate on rabbit red blood cell hexokinase.

1. Orthophosphate (Pi) at low concentrations, is able to activate the glucose 6-phosphate, glucose-1,6-diphosphate or 2,3-diphosphoglycerate-inhibited hexokinase (E.C. 2.7.1.1). In contrast, at high concentrations it is competitive inhibitor of MgATP2- with a Ki of 20 mM. 2. The Pi effect on inhibited hexokinase is pH dependent and becomes lower as the pH increase. The similar pH-dependence of the Ki of glucose-1,6-diphosphate with the pH-independence of the Ki of glucose 6-phosphate here reported, suggest the coincidence of the C-1 phosphate, of glucose-1,6-diphosphate and Pi binding sites. 3. Activation of uninhibited hexokinase by Pi at pH lower than the physiological ones has been demonstrated to be an artefact.

Adenosine Triphosphate↗