Search PubMed⌕ Search

Biomedical subjects

F Canestrari

Publications and source records attributed to F Canestrari.

At least 37 records · Page 2Linked to original sources
PubMed1992

[Uptake of 86Rb by human erythrocytes: modification of the method and applications].

In this study we applied a method generally used for the study of Na+,K(+)-ATPase, as well as other systems of potassium transport, which makes use of a rubidium isotope (86Rb) as analogue of the potassium and is known as uptake of the 86Rb. This method proved to be particularly sensitive and versatile for kinetic studies of this pump system, allowing to assess possible alterations. Its application in the study of sodium and potassium transport in erythrocytes of uremic subjects in extracorporeal dialysis made it possible to reveal certain alterations due both to pump-dependent and pump-independent uptake. In fact, the results show the hypothesis of restoration of Na+,K(+)-pump activity for elimination during dialysis of one or more inhibitor present in the uremic plasma. Furthermore, a reduction in aspecific flows was noted which could be the result of more generalized damage of the membrane.

Adult↗
PubMed1991

[Various properties of the Na+, K(+)-ATPase and the Mg (2+)-ATPase in erythrocytes from normotensive and hypertensive subjects].

In the present work we reported the results of the study of erythrocyte membrane Na+,K(+)-adenosine triphosphatase (ATPase) and Mg(2+)-ATPase in patients with essential hypertension and controls. In the 40 patients with hypertension, a more marked decrease of Na+, K(+)-ATPase was observed. The behavior of the enzyme at Mg2+ activation, ouabain inhibition and the response to different temperature suggest the possibility of differences between the two groups. The normal erythrocyte Mg(2+)-ATPase activity in two groups suggest also the possible role of ratio Na+, K(+)-ATPase/Mg(2+)-ATPase in the study of essential hypertension. However the relevance of magnesium and Mg(2+)-ATPase to the pathogenesis of essential hypertension remains unclear but merits further study. On the basis of these considerations the aim of the present study was to identify, in a kinetic approach, the presence of different abnormalities of Na+ transport and Na+, K(+)-ATPase in erythrocytes from patients with essential hypertension. Much evidence has supported the hypothesis that essential hypertension is a heterogeneous disease in the pathophysiological mechanisms as well as in its clinical and therapeutical consideration.

Adenosine Diphosphate↗
PubMed1987

A very fast ion-pair reversed-phase HPLC method for the separation of the most significant nucleotides and their degradation products in human red blood cells.

A simple and fast ion pair reversed-phase high-performance liquid chromatographic method has been developed for the simultaneous determination of ATP, ADP, AMP, GTP, GDP, IMP, NADP+, NADPH+, NAD+, NADH, ADP-ribose, inosine, adenosine, hypoxanthine, and xanthine. This method allows us to have a complete picture of the most important nucleotides present in fresh human erythrocytes. Furthermore it is particularly useful in the study of the erythrocyte adenine nucleotide catabolism allowing the detection of degradation products such as IMP, inosine, adenosine, hypoxanthine, and xanthine. The separation of the compounds under investigation is achieved in less than 15 min using a reversed-phase 3-micron Supelcosil LC-18 column and adding tetrabutylammonium, as ion-pair agent, to the buffers. The short time of analysis, the high reproducibility of the system, and the accurate evaluation of the compounds of interest make this method particularly suitable for routine analysis. Finally it is possible to use this assay as an alternative method of measuring activities of enzymes which catalyze reactions involving some of these compounds, as in the case of Na+-K+ ATPase, AMP deaminase, and adenosine deaminase.

Chromatography, High Pressure Liquid↗
PubMed1987

Adenine and pyridine nucleotides in the red blood cells of subjects with solid tumors.

The concentration of adenine (ATP, ADP, AMP) and pyridine (NADP+, NADPH, NAD+, NADH) nucleotides in the erythrocytes of subjects affected by solid tumors was evaluated using a method which allows their simultaneous extraction and reverse-phase high-performance liquid chromatographic analysis. The results showed a lower level of ATP in the erythrocytes of subjects affected by solid tumors, whereas no significant modifications were observed in the other compounds. In fact, the mean value of ATP in these subjects was 27% lower than that of normal adults. This fact is discussed in relation to other enzymatic and metabolic modifications previously observed in red blood cells.

Adenine Nucleotides↗
PubMed1987

Solid tumors and enzyme activity in human lymphocytes.

A study on the enzyme activity of glucose metabolism in the lymphocytes of patients with solid malignant tumors is reported. The results have shown a 30% mean increase of the hexokinase (HK) activity in patients with solid malignant tumors as compared to the mean value observed in a group of healthy subjects. A relationship between level of HK increase and stage of tumor was also observed. The other examined enzyme activities, phosphofructokinase (PFK), pyruvate-kinase (PK), phosphoglycerate-kinase (PGK), phosphoglucoisomerase (PGI), glyceraldehyde-phosphate dehydrogenase (GAPD) glucose-6-phosphate dehydrogenase (G-6PD), 6-phosphogluconate dehydrogenase (6-PGD) and enolase did not show significant changes. It is concluded that even though the use of HK as tumor marker cannot be hypothesized at the present time, a significant relation between an increased activity of this enzyme and presence of the tumor is unquestionable. Therefore, this biochemical effect induced away from the neoplastic tissue deserves further study.

Adenocarcinoma↗
PubMed1986

Redox and energetic state of red blood cells in G6PD deficiency, heterozygous beta-thalassemia and the combination of both.

The levels of ATP, ADP, AMP, NADP, NADPH, NAD, NADH and reduced glutathione were determined in the red blood cells of individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, beta-thalassemia (beta-thal) heterozygotes and in a boy carrying both mutations. The results obtained confirmed a reduced concentration of NADPH in G6PD deficiency and showed that with the combination of both diseases, the red blood cell contained practically undetectable levels of NADPH. Assays of some red blood cell enzyme activities known to be markedly influenced by cell age suggested that a younger mean red cell population is present in beta-thal/G6PD deficiency. Thus, the marked oxidative stress caused by beta-thal, that is apparently incompatible with G6PD deficiency, in fact exists, probably because of the residual activity of this enzyme in the younger red cells.

Adenine Nucleotides↗
PubMed1985

Human erythrocyte hexokinase deficiency: a new variant with abnormal kinetic properties.

A 14-month-old child who had a haemolytic episode when he was 5 years old, and with psychomotor retardation, was found to have decreased red cell hexokinase activity. The mutant enzyme was characterized by an increased affinity for glucose associated with an increased inhibition constant for glucose-1,6-diphosphate. Affinity for Mg ATP2-, heat stability and pH-optimum were normal. The isozymic pattern of the red cell enzyme was normal but all the molecular forms were present in reduced amounts. The kinetics of decay of hexokinase during cell ageing was also normal. Glucose consumption of the hexokinase deficient cells was 60-65% of the controls while the amount metabolized through the hexose monophosphate shunt was unchanged. Red cell 2,3-diphosphoglycerate and glucose-6-phosphate levels were normal in the proband but reduced in the erythrocytes of his parents, who were heterozygous for the defect but had normal haematological data. Comparison with the 13 previously reported cases of hexokinase deficiency confirms the broad phenotypic variability that characterizes this disorder.

Blood Glucose↗
PubMed1983

Red blood cell hexokinase in tumor bearing mice.

Red blood cell hexokinase of tumor-bearing BALB/c mice was found to be 35% higher than in the normal controls, whereas glucose 6-phosphate-dehydrogenase and other red blood cell glycolytic enzymes were in the normal range. This hexokinase increase cannot be explained by a mean younger red cell population because normal hematological data and normal red cell enzymes, known as red cell age-markers, have been found in tumor-bearing mice. The isozymic pattern of red cell hexokinase is not modified in the tumor-bearing mice.

Animals↗
PubMed1983

Relationship between erythrocyte hexokinase in cancer patients and red cell age.

A study of hexokinase isozymic pattern and age dependence of the enzyme was carried out on erythrocytes of 4 patients with adenocarcinoma of the gastrointestinal tract. On the basis of our results, we think that the increase in hexokinase activity previously reported and the increase in both subtypes (Ia and Ib) of the enzyme herein described are not due to a mean younger red cell population caused by secondary anemia, which is frequently present in cancer patients.

Adenocarcinoma↗
PubMed1982

Multiple forms of human red blood cell hexokinase. Preparation, characterization, and age dependence.

Human red blood cell hexokinase (EC 2.7.1.1) has been shown to exist in multiple molecular forms which are separable by ion exchange chromatography. Of the major forms, designated hexokinase Ia, Ib, and Ic, only hexokinase Ia corresponds to hexokinase type I from human liver, while the others differ from every other previously reported hexokinase isozyme. Hexokinase Ib is the predominant form in the fetal erythrocytes, while it is present at lower levels in the red blood cells of adults. Analysis of the hexokinase isozymic pattern in red cells of different mean age shows that the level of hexokinase Ib is also dependent on the age of the cell. The three major forms of hexokinase have the same molecular weight of 100,000, by sedimentation velocity on sucrose density gradients, the same Michaelis constants, substrate and coenzyme specificity, pH-dependent activity, and the same thermal stability. The only significant differences were found in the isoelectric points which were 5.7 pH units for hexokinase Ia, 5.5 pH units for hexokinase Ib, and 5.35 pH units for hexokinase Ic. These data, together with that previously reported for rabbit erythrocytes (Stocchi, V., Magnani, M., Canestrari, F., Dachà, M., and Fornaini, G. (1981) J. Biol. Chem. 256, 7856-7861) suggest that the presence of multiple forms of hexokinase is a common phenomenon in mammalian red blood cells.

Adult↗
PubMed1981

Rabbit red blood cell hexokinase. Evidence for two distinct forms, and their purification and characterization from reticulocytes.

Rabbit hexokinase (EC 2.7.1.1) has been shown to exist in the soluble fraction of reticulocytes as two distinct molecular forms, designated hexokinase Ia and hexokinase Ib, which are separable by ion exchange chromatography and polyacrylamide gel electrophoresis. Hexokinase Ia was found to be similar to the brain enzyme, while hexokinase Ib differs from every other previously reported hexokinase isozyme. Reticulocyte hexokinase Ia and Ib have been purified 55,000-and 50,000-fold, respectively, by a combination of ion exchange chromatography, affinity chromatography, and preparative polyacrylamide gel electrophoresis, as proteins homogeneous by sodium dodecyl sulfate-gel electrophoresis. The native proteins have the same molecular weight of 105,000 by gel filtration and sedimentation velocity on sucrose density gradients. Sodium dodecyl sulfate-polyacrylamide gels have a molecular weight of 104,000, indicating that the two forms are monomers. Hexokinase Ia had a pI of 6.2 to 6.3 pH units while hexokinase Ib had a pI of 5.7 to 5.8 pH units by isoelectric focusing. The two enzymes were specific for Mg.ATP and Mg.ITP as the nucleotide substrates. Several hexoses could be phosphorylated by hexokinase Ia and Ib with different affinities.

Animals↗
PubMed1980

Modification of the hexokinase activity in the red blood cells of subjects with differentiated adenocarcinoma.

In the present work we found a significant increase of erythrocyte HK activity in subjects suffering from differentiated adenocarcinoma. Some erythrocyte enzymatic activities (such as HK, PK, G-6-PD, 6-PGD, PHI and GR) in the red blood cells of 96 subjects, of which 55 were healthy or with noncancerous pathology and 41 had malignant tumors, are considered. Evident modification was shown only for the HK, which together with PFK and PK are limiting steps of glycolysis.

Adenocarcinoma↗
PubMed1977

Inherited erythrocyte pyruvate kinase deficiency: Studies on 15 members of two related families.

The case of a haemolytic non-spherocytic anaemia with pyruvate kinase (PK) deficiency is reported. The investigation concerns two families with a low level of PK. In the propositus and in the members of his family we have also examined the behaviour of some enzymes and the concentration of red cell metabolites. We confirm the heterogeneity of the manifestation and agree that anaemias due to PK deficiency are complex forms in which the enzyme defect is only one of the symptoms.

Anemia, Hemolytic, Congenital Nonspherocytic↗
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↗