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D Colomer

Publications and source records attributed to D Colomer.

63 records · Page 4Linked to original sources
PubMed1991

Erythrocyte fructose 2,6-bisphosphate content in congenital hemolytic anemias.

We have investigated the levels of fructose 2,6-bisphosphate and its synthesizing enzyme 6-phosphofructo-2-kinase in red blood cells from different congenital anemias. Fructose 2,6-bisphosphate concentration and 6-phosphofructo-2-kinase activity are markedly influenced by the number of reticulocytes in all the cases studied with the exception of homozygous pyruvate kinase deficiency, where no correlation was observed with the percentage of reticulocytes.

Anemia, Hemolytic, Congenital↗
PubMed1990

Association of adenosine deaminase with erythrocyte and platelet plasma membrane: an immunological study using light and electron microscopy.

Adenosine deaminase has been localized in the plasma membrane of erythrocytes and platelets by means of immunological techniques using light and electron microscopy with cells in suspension. In erythrocytes, adenosine deaminase is associated with the external side of the plasma membrane. In platelets, the enzyme is associated with the external side of the plasma membrane, which is known to extend through the canalicular system of these cells. These results confirm our previous findings, based on biochemical studies, concerning the attachment of the enzyme to cell membranes.

Adenosine Deaminase↗
PubMed1990

[Chronic non-spherocytic hemolytic anemia caused by pyruvate kinase deficiency in a Costa Rican family carrying hemoglobin C disease].

The two first homozygous (or double heterozygous) cases of pyruvate kinase (PK) deficiency found in a Costa Rica family with no signs of consanguinity are reported. The clinical manifestations of the deficiency were present in both cases, these being enhanced in one of them by pregnancy. The family study performed showed the heterozygous character of the PK deficiency in all cases, plus the demonstration in two instances (father and brother) of a heterozygous haemoglobin C disease. The importance of the PK/HK quotient in the identification of the PK deficiency heterozygous is stressed, especially when the enzyme activity registered from haemolysates falls within the normal range.

Adult↗
PubMed1989

Chronic nonspherocytic hemolytic anemia (CNSHA) and glucose 6 phosphate dehydrogenase (G6PD) deficiency in a patient with familial amyloidotic polyneuropathy (FAP). Molecular study of a new variant (G6PD Clinic) with markedly acidic pH optimum.

A new glucose-6-phosphate dehydrogenase (G6PD) variant with severe erythrocytic G6PD deficiency and a unique pH optimum is described in a young patient with chronic nonspherocytic hemolytic anemia (CNSHA) and familial amyloidotic polyneuropathy (FAP). Chronic hemolysis was present in the absence of infections, oxidant drugs or ingestion of faba beans. Residual enzyme activity was about 2.6% and 63% of normal activity in erythrocytes and leucocytes, respectively. A molecular study using standard methods showed G6PD in the patient to have normal electrophoretic mobility (at pH 7.0, 8.0 and 8.8), normal apparent affinity for substrates (Km, G6P and NADP) and a slightly abnormal utilization of substrate analogues (decreased deamino-NADP and increased 2-deoxyglucose-6-phosphate utilization). Heat stability was found to be markedly decreased (8% of residual activity after 20 min of incubation at 46 degrees C) and a particular characteristic of this enzyme was a biphasic pH curve with a greatly increased activity at low pH. Although molecular characteristics of this variant closely resemble those of G6PD Bangkok and G6PD Duarte, it can be distinguished from these and all other previously reported variants by virtue of its unusual pH curve. Therefore the present variant has been designated G6PD Clinic to distinguish it from other G6PD variants previously described.

Adult↗
PubMed1989

Relationship between lymphocyte size and enzyme activities in two morphological variants of B-chronic lymphocytic leukaemia.

The activities of the key glycolytic enzymes phosphofructokinase (PFK), pyruvate kinase (PK) and hexokinase in addition to adenosine deaminase, purine nucleoside phosphorylase (PNP) and lactate dehydrogenase (LDH) have been measured in lymphocytes from 39 cases with B-chronic lymphocytic leukaemia (B-CLL). According to the percentage of circulating large non-granular atypical lymphocytes (AL) the B-CLL cases were classified as: typical (less than 10% of AL; 28 cases) and atypical (10-25% AL; 11 cases). In both groups the median lymphocyte volume (MLV) was assessed and correlated with the correspondent enzyme activities. The MLV of B-CLL lymphocytes was significantly (p less than 0.001) decreased (149.9 +/- 19.4 fl) as compared to normal B lymphocytes (175.1 +/- 14.5 fl) and it was significantly (p less than 0.001) lower in typical B-CLL (141.8 +/- 12.2 fl) than in atypical B-CLL (172.0 +/- 17.2 fl). Furthermore, in patients with typical B-CLL, all enzyme activities when expressed as U/10(9) cells were, with the exception of PFK, significantly decreased compared to normal B lymphocytes. However, when the results were expressed as U/ml cells, only PK, PNP and LDH remained significantly low. These findings demonstrate that the determination of MLV in addition to morphology may be a useful tool to distinguish the two previously described morphological B-CLL variants (typical and atypical) and that these two different B-CLL groups are also distinguishable on the basis of three enzyme activities, PK, PNP and LDH which have been shown to be less dependent on cell size than the other enzymes, also studied here.

Adenosine Deaminase↗
PubMed1988

Combined assay of adenosine deaminase, purine nucleoside phosphorylase, and lactate dehydrogenase in the early clinical evaluation of B-chronic lymphocytic leukemia.

The levels of adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), lactic dehydrogenase (LDH), and LDH isoenzyme patterns (LD1 to LD5) have been measured in lymphocyte extract from 28 patients with B-chronic lymphocytic leukemia (B-CLL). The activities of ADA, PNP, and LDH have been correlated with two morphological groups of B-CLL classified according to the percentage of large, nongranular, atypical lymphocytes (AL) in peripheral blood: "typical" B-CLL (less than 10% of AL, 21 cases) and "atypical" B-CLL (10-25% of AL, seven cases). Patients with atypical B-CLL had significantly (P less than 0.001) higher activities of ADA (0.46 +/- 0.17 U/10(9) cells), PNP (1.74 +/- 1.0 U/10(9) cells), and LDH (48.3 +/- 9.7 U/10(9) cells) than patients with typical B-CLL (ADA, 0.29 +/- 0.1 U/10(9) cells; PNP, 0.58 +/- 0.23 U/10(9) cells; and LDH, 29 +/- 10 U/10(9) cells). In addition, the "treatment-free period" was also significantly (P less than 0.025) shorter in the group of atypical B-CLL compared with the typical B-CLL group. No clear-cut statistical differences in lymphocyte surface markers or in several other prognostic factors between the two subgroups of B-CLL were found. The present study supports the idea that in B-CLL the simultaneous determination of ADA, PNP, and LDH might be helpful in better understanding the pathophysiology, prognosis, and natural history of the disease.

Adenosine Deaminase↗
PubMed1988

Increase of enzyme activities following the in vitro peroxidation of normal human red blood cells.

Red blood cells (RBCs) from 15 normal human blood samples were incubated with different concentrations of hydrogen peroxide in sodium azide, and the effects of the peroxidation on several glycolytic and nucleotidic enzyme activities were investigated. The release of malonyl dialdehyde (MDA) and methemoglobin formation were used as indicators of RBC peroxidation. The increase of H2O2, final concentration from 0.1 to 5 mmol/l, resulted in a progressive rise of almost all glycolytic enzyme activities, especially those of aldolase (200% of normal at 1 mmol/l), phosphoglycerate kinase (140%), phosphoglycerate mutase (136%), pyruvate kinase (130%) and glutathione peroxidase (130%), and in a decrease of glucose-6-phosphate dehydrogenase (68%) and pyrimidine-5-nucleotidase (23%). The addition of beta-mercaptoethanol to the incubation medium abolished only the effect of 1 mmol/l H2O2 on glucose-6-phosphate dehydrogenase.

Azides↗
PubMed1987

Control of phosphofructokinase by fructose 2,6-bisphosphate in B-lymphocytes and B-chronic lymphocytic leukemia cells.

The levels of fructose 2,6-bisphosphate and glucose 1,6-bisphosphate and the activities of the key glycolytic enzymes have been studied in T- and B-lymphocytes, and in B-chronic lymphocytic leukemia cells (B-CLL). In both kinds of cells these two bisphosphorylated metabolites have been identified and are present at similar concentrations. Their phosphofructokinase, like that of other normal or tumoral cells, is sensitive to these activators. Fructose 2,6-bisphosphate is the most potent stimulator; it displays the properties of a positive effector. It greatly increases the affinity for fructose 6-phosphate and relieves the inhibition by adenosine triphosphate, without changing Vmax. This effect is also synergistic with adenosine monophosphate. Despite few differences in the activity of phosphofructokinase and in the content of its main effectors in B-lymphocytes and in B-CLL cells, the kinetic properties of the enzyme from B-CLL cells were different, the enzyme being more sensitive to fructose 2,6-bisphosphate (Ka 2 orders of magnitude lower) and to glucose 1,6-bisphosphate than the enzyme from normal lymphocytes. The results reported showing that phosphofructokinase from B-CLL lymphocytes is altered in regulatory properties and the observed changes, in comparison to phosphofructokinase from normal B-lymphocytes, fit well with the hypothesis that fructose 2,6-bisphosphate can also assume a regulatory role in these cancer cells characterized by proliferation and accumulation of relatively mature-appearing lymphocytes.

B-Lymphocytes↗