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Biomedical subjects

F Palma

Publications and source records attributed to F Palma.

At least 55 records · Page 3Linked to original sources
PubMed1985

Glucose 1,6-bisphosphate decline in human erythrocytes: possible involvement of phosphoglucomutase PGM2 isoenzymes.

Human erythrocytes incubated with various sugars lower their glucose 1,6-bisphosphate (Glc-1,6-P2) content, as do haemolysates containing exogenous Glc-1,6-P2 incubated with sugar monophosphates (sugar-P). Experiments performed with isolated erythrocyte phosphoglucomutase (PGM) isoenzymes indicate that only definite isoenzymatic forms, namely PGM2, are able to consume Glc-1,6-P2 during the mutation of sugar-P other than glucose-P. In this process a phosphate group is released from Glc-1,6-P2 and can be partially recovered in the biphosphate of the mutated sugar-P. The relevance of this mechanism of Glc-1,6-P2 degradation is discussed in regard to the physiological turnover of the biphosphate.

Adenine Nucleotides↗
PubMed1984

[Degradative pathways of glucose 1,6-diphosphate in human erythrocytes].

In this study human erythrocytes have been incubated with various effectors most of which able to decrease the G1, 6P2 content. By using haemolysates and partially purified phosphoglucomutase isoenzymes we provide evidence that the G1, 6P2 decrease can be attributed to the ability of phosphoglucomutase PGM2 isoenzymes to mutate various sugar monophosphates. These isoenzymes, phosphorylated by G1, 6P2, may transfer the phosphate group to monophosphate sugars thus releasing the respective bisphosphate.

Adenine Nucleotides↗
PubMed1984

Acetaldehyde influences glucose 1,6-bisphosphate level of human erythrocytes in vitro and in vivo.

In intact erythrocytes from normal adults, acetaldehyde, besides inducing metabolite modifications otherwise observed, markedly decreases the glucose 1,6-bisphosphate (G1,6P2) level. Pyruvate rapidly reverses the acetaldehyde effects. Also in vivo, the acetaldehyde that occurs in the blood stream after heavy alcohol intake produces a significant decrease of the erythrocyte G1,6P2 concentration. These changes support the role of 1,3-bisphosphoglycerate as the first substrate in the G1,6P2 synthesis. The significance of the glucose bisphosphate as glycolytic modulator is also discussed.

Acetaldehyde↗
PubMed1983

Vanadate affects glucose metabolism of human erythrocytes.

Vanadate causes a rapid breakdown of 2,3-bisphosphoglycerate in intact erythrocytes. This metabolite is nearly stoichiometrically transformed into pyruvate, which changes the cell redox state and enhances the glycolytic flux. The results show that the vanadate effect on 2,3-bisphosphoglycerate, also evident in hemolysates, is attributable to the stimulation of a phosphatase activity of the phosphoglycerate mutase. In agreement with others (J. Carreras, F. Climent, R. Bartrons, and G. Pons (1982) Biochim. Biophys. Acta 705, 238-242), vanadate is thought to destabilize the phosphoryl form of this enzyme which shows competitive inhibition between the ion and 2,3-bisphosphoglycerate in the mutase reaction. A competitive inhibition between vanadate and glucose 1,6-bisphosphate is also found for phosphoglucomutase, without evidence for phosphatase activity toward the bisphosphate cofactor.

2,3-Diphosphoglycerate↗
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↗
PubMed1983

Red cell metabolism affects lactate and pyruvate partition across the plasma membrane.

The influence on red cell metabolism of increasing the glucose concentration or the pH of the medium has been examined in order to compare the modification of the lactate/pyruvate ratio inside and outside the cell. In both situations, we evidenced a constancy in the intracellular lactate/pyruvate ratio and an increase in the extracellular one, thus suggesting that the cell efficiently opposes cytoplasmic modifications. In fact an increase of lactate efflux takes place when the intracellular pyruvate decreases. The implications of these changes in the two compartments are discussed on the basis of the available results.

Cell Compartmentation↗
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↗
PubMed1980

Displacement potency of vitamin D2 analogs in competitive protein-binding assays for 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D3, and 1,25-dihydroxyvitamin D3.

24(R),25-Dihydroxyergocalciferol [24,25-(OH)2-D2] is 1.7 times less potent than 24 (R), 25-(OH)2D3, 25-Hydroxyvitamin D2 (25OHD2), or 25OHD3 in the displacement of (3H)25OHD3 from rat serum binding proteins. 1,25-(OH)2D2 is 1.3 times less potent than 1,25-(OH)2D3 in the displacement of (3H)1,25-(OH)2D3 from a chick intestinal binding receptor. In light of binding affinity and chromatographic differences between vitamin D3 and its D2 analogs, it is our view that methods which purport to measure 1,25-(OH)2D and 24,25-(OH)2D probably understimate the contributions of D2 metabolites. This is particularly important in the case of plasma extracts from patients given large doses of vitamin D2.

24,25-Dihydroxyvitamin D 3↗