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At least 919 records · Page 51Linked to original sources
PubMed1987

Characteristics of red cell pyruvate kinase (PK) and pyrimidine 5'nucleotidase (P5N) abnormalities in acute leukaemia and chronic lymphoid diseases with leukaemic expression.

Red cell pyruvate kinase (PK), pyrimidine 5'nucleotidase (P5N) and reduced glutathione content (GSH) were studied in 126 untreated patients with acute leukaemia (AL, 80 cases), chronic lymphocytic leukaemia (B-CLL, 38 cases) and B-cell lymphoma with leukaemic expression (LSCL, eight cases). Acute leukaemias were classified into lymphoblastic (ALL) and non-lymphoblastic (ANLL), the latter have been further sub-divided into four different variants according to FAB morphological criteria (1976). A significant decrease of PK activity was observed only in the ANLL group, leading to a clear-cut difference with the ALL group where a normal value was obtained. The decrease of P5N activity was similar in all the morphological variants of ANLL and no abnormalities in the low PEP assay system or after fructose 1,6-bisphosphate (Fru 1,6-P2) activation were observed. P5N activity was found to be significantly decreased in all groups of patients except in B-CLL, where it was normal. In regards to the different morphological groups of ANLL, a striking decrease of P5N activity was observed in the M3 variant. Although red cell GSH content was significantly increased in all groups of patients, no correlation was demonstrated between the raised GSH levels and the decreased P5N activities.

5'-Nucleotidase↗
PubMed1987

Pyrimidine nucleoside monophosphate kinase hyperactivity in hereditary erythrocyte pyrimidine 5'-nucleotidase deficiency.

The pyrimidine nucleoside triphosphates (CTP, UTP) increase in the pyrimidine 5'-nucleotidase (P5N) deficient red blood cell (RBC) to a greater degree than do the pyrimidine nucleoside monophosphates (CMP, UMP). Pyrimidine nucleoside monophosphate (PNMP) kinase phosphorylates CMP and UMP to their respective phosphodiesters. We tested the hypothesis that increased PNMP kinase activity contributes to the disproportionate increase in CTP and UTP in the P5N deficient RBC. CMP and UMP kinase activities were increased in high reticulocyte (4.4 +/- 2.1 and 8.5 +/- 3.3 mumol/ml RBC per minute) compared to normal RBC (2.8 +/- 1.0 and 6.0 +/- 2.5 mumol/ml RBC per minute). P5N deficient RBC (n = 2) had significantly increased CMP and UMP kinase activities (14.0 and 26.5 mumol/ml RBC per minute). UMP and CDP-ethanolamine were able to increase the activity of CMP kinase in crude haemolysate and the activity of partially purified enzyme. Since the Km for CMP of CMP kinase was 33 mumol/l in P5N deficient RBC and since the CMP concentration is 25-90 mumol/l in the P5N deficient RBC, the enzyme should be nearly saturated with CMP in the P5N deficient RBC. Thus, PNMP kinase hyperactivity appears to contribute to the disproportionate increase in CTP and UTP in the P5N deficient RBC.

5'-Nucleotidase↗
PubMed1983

5'-nucleotidase activity in myeloma cells.

Plasma cells were studied cytochemically for 5'-nucleotidase (5'-N) activity in bone marrow smears from 11 patients with multiple myeloma and 12 cases with no haematological disorders but with adequate numbers of plasma cells. The activity of 5'-N could be demonstrated in about 90% of myelomatous plasma cells. The non-myelomatous plasma cells of control smears were negative for 5'-N activity. The activity of 5'-N did not seem to be affected by storage of unfixed smears for up to 5 months at room temperature.

5'-Nucleotidase↗
PubMedDate not supplied

Changes of 5'-nucleotidase activity in cultured glioma cells.

Changes of 5'-nucleotidase (5'-N) activity during subcultivation of C6 clonal rat glioma cells were studied histochemically, cytochemically and biochemically. Two different cell populations were seeded with high or low cell density respectively. 5'-N activity in cultured cells increased continuously in both populations. The enzyme activity was always higher in the cells growing in high density than in those growing in low density, and this difference became statistically significant after 6 days of subcultivation. It seemed likely that the increase in 5'-N activity depended on cell density, not on the frequency of mitosis. Cytochemically, enzyme activity was detected on the outer surface of the plasma membrane of cell bodies or cell processes. Strong activity was found on the processes and cell membranes where cells touched each other. In the regions where cells had intimate cell-to-cell contact, marked elevation of the enzyme activity was seen. Increased 5'-N activity, which appeared to depend on cell density, was considered to be related with this cell-to-cell contact.

5'-Nucleotidase↗
PubMed1984

2',3'-cyclic nucleotide 3'-phosphodiesterase and 5'-nucleotidase in the central nervous system of a myelin-deficient rat mutant.

2',3'-Cyclic nucleotide 3'-phosphodiesterase activity was examined in brains and spinal cords of normal and myelin-deficient Wistar rats. While the activity in normal brains increased from 0.2 mumol/min/mg protein (units) at 6-10 days to 3.5 units at 25 days of postnatal age, the activity in the myelin-deficient rat remained at 0.2-0.3 units over the same period. In spinal cord, the normal activities were 5.7 and 10.9 units at 12 and 20 days, respectively, whereas they declined in the myelin-deficient rat from 1.06 to 0.79 units for the same age points. 5'-Nucleotidase activities in brain and spinal cord were normal in the myelin deficient rat at both ages.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1985

Biochemical studies on 5'-nucleotidase of Schwann cells in degenerated nerve.

This report describes the partial characterization of 5'-nucleotidase (5'-AMPase) in Schwann-cell plasmalemmae (PM) prepared from degenerated cat sciatic nerve. 5'-AMPase was enriched 3.7-fold in the PM fraction over that of the crude homogenate preparation. The plant lectin concanavalin-A (Con-A) reduced Schwann cell PM 5'-AMPase activity in a concentration-dependent manner (30-600 micrograms/ml). Plasma membrane 5'-AMPase activity was maximally inhibited to 20% of control values by Con-A (400-600 micrograms/ml), and activity returned to control levels by pretreatment with the hapten sugar alpha-methyl-D-mannoside (50 mM). Equimolar concentrations of UDP and ADP (100 microM) reduced the rate of hydrolysis of labeled AMP to labeled adenosine in PM to 45% and 35% of control, respectively. This is the first study to characterize a Schwann-cell PM enzyme and demonstrates that 5'-AMPase may be used as a Schwann-cell PM marker enzyme.

5'-Nucleotidase↗
PubMed1987

Immunologic and virologic findings in hemophiliacs do not correlate with ecto-5'nucleotidase activity of peripheral blood lymphocytes. A difference with homosexual men.

It has been recently demonstrated that ecto-5'nucleotidase (5'NT) activity is significantly decreased in the peripheral blood lymphocytes (PBL) of homosexual men. This paper reports a study of PBL 5'NT activity in 38 hemophiliacs at risk for the acquired immunodeficiency syndrome (AIDS). The enzyme activity was correlated to the immunologic and virologic data. T-cell subset distribution was unbalanced and directly correlated with the cumulative amount of AHF infused. PBL 5'NT activity, however, was similar to that of healthy controls. 6 patients displayed serum antibodies to the human immunodeficiency virus (HIV) but no decrease in PBL 5'NT activity. In conclusion, these data indicate that both heavily treated and seropositive as well as untreated hemophiliacs have normal PBL 5'NT activity. This striking dissimilarity between homosexual men and hemophiliacs suggests that some immunologic alterations leading to 5'NT deficiency occur in the former only.

5'-Nucleotidase↗
PubMed1988

Decreased B lymphocyte ecto-5'nucleotidase and increased adenosine deaminase in mononuclear cells from patients infected with human immunodeficiency virus.

The levels of purine enzyme activities were studied in 10 patients with acquired immunodeficiency syndrome (AIDS) or AIDS related complex (ARC) and in 6 healthy individuals with antibodies against human immunodeficiency virus (HIV). All AIDS/ARC patients studied had ecto-5'nucleotidase (ecto-5'NUC) activity in B lymphocytes below the normal range and 4 out of 6 clinically healthy HIV-positive likewise had reduced activity. Increased numbers of activated B lymphocytes were found both in the group of healthy HIV positive individuals and in AIDS/ARC patients. Further studies are needed to define whether the decrease in ecto-5'NUC activity on the B lymphocytes is a result of increased activation of the cells or of a B cell defect. No significant changes were found in ecto-5'NUC levels in T lymphocytes or mononuclear cells (MNC), neither in the group of AIDS/ARC patients nor in the healthy HIV-positive group. Both AIDS/ARC patients and healthy individuals with antibodies against HIV had increased levels of adenosine deaminase (ADA) activity in mononuclear cells, but only in the group of AIDS/ARC patients was the increase significant. No changes were found in purine nucleoside phosphorylase (PNP) activity in the two groups tested. From these investigations of purine enzyme levels and other markers of immune function in both sick and healthy HIV infected individuals we conclude that the observed changes in ecto-5'NUC and ADA activities in HIV infected patients are not a direct result of the HIV infection but develop early in the course of the disease.

5'-Nucleotidase↗
PubMed1982

Partial nucleotide limitation induces phosphodiesterase I and 5'-nucleotidase in Bacillus subtilis.

Changes in the specific activity of enzymes involved in the degradation of RNA and nucleotides were measured in Bacillus subtilis under conditions of guanine deprivation, which initiates sporulation, and uracil deprivation, which does not initiate sporulation. Whereas the specific activities of most of the enzymes studied increased by less than a factor of 3, those of 5'-mononucleotide-producing phosphodiesterase and 5'-nucleotidase increased at least eightfold under both deprivation conditions.

5'-Nucleotidase↗
PubMed1986

A simplified method for determining erythrocyte pyrimidine 5'-nucleotidase (P5N) activity by HPLC and its value in monitoring lead exposure.

The method for determining erythrocyte pyrimidine 5'-nucleotidase (P5N EC 3.1.3.5) activity has been simplified using an automated high performance liquid chromatograph (HPLC). The activity determined by the simplified method agreed closely with that obtained by conventional methods. In 161 lead workers P5N activity declined linearly with increasing blood lead concentrations (Pb-B) between 20 and 80 micrograms/100 g, and correlated well with Pb-B (r = -0.87). For the same group of workers, correlation coefficients between Pb-B v ALA-D activity, zinc protoporphyrin, ALA-U, and coproporphyrin were -0.87, 0.73, 0.70, and 0.32, respectively. At Pb-B greater than or equal to 40 micrograms/100 g, the validity of P5N (1.86 at a cut off of 10 less than or equal to units) was higher than that of other indicators examined. P5N activity was fairly stable during the storage of samples for two weeks at 4 degrees C. Determination of P5N activity by this method may be a useful indicator in screening for moderate exposure to lead.

5'-Nucleotidase↗
PubMed1989

Aplastic crisis due to human B19 parvovirus infection in red cell pyrimidine-5'-nucleotidase deficiency.

Two siblings with chronic hemolytic anemia due to red cell pyrimidine-5'-nucleotidase (P-5'-N) deficiency, presented within a few days of each other with a febrile illness and pancytopenia. The cause of the aplastic crisis was an acute infection with human B19 parvovirus (B19 HPV) as proven by immunoelectron microscopy and DNA hybridization. This is the first report on the association of B19-HPV-related aplastic crisis with P-5'-N deficiency.

5'-Nucleotidase↗
PubMed1981

A case of hemolytic anemia due to erythrocyte pyrimidine 5'-nucleotidase deficiency.

A propositus, the offspring of a first-cousin marriage, was presented with severe hemolytic anemia, splenomegaly, jaundice, and growth retardation. Marked basophilic stippling of erythrocytes was shown by Wright's stain. Erythrocyte 5'-nucleotidase activity was found markedly decreased, whereas red blood cell glucose-6-phosphate dehydrogenase activity was elevated as the reduced glutathione level. His growth and anemia improved following splenectomy. His sister was also similarly affected.

5'-Nucleotidase↗
PubMed1985

5'-Nucleotidase activities in human fetus.

Specific 5'-nucleotidase (5'-N) activity in 17 human fetuses was systemically studied in order to get basic values of the enzyme activity. A wide spectrum of 5'-N activity among the organs was revealed. Very strong activity was found in placenta (42.62 +/- 19.24 nmol adenosine/mg protein/min), skeletal muscle (31.80 +/- 11.10) and skin (27.31 +/- 13.00); strong activity in liver (18.96 +/- 7.60), pituitary (15.06 +/- 6.13) and thyroid (12.69 +/- 4.47); moderate activity in lung (8.43 +/- 3.68), pancreas (8.20 +/- 2.26), small intestine (8.07 +/- 2.28), lymph node (7.26 +/- 2.22), thymus (7.06 +/- 2.52), spinal cord (5.86 +/- 1.96) and spleen (5.65 +/- 2.52), and weak activity in testis (4.02 +/- 0.79), heart (3.95 +/- 1.22), adrenal (3.46 +/- 1.68), kidney (3.16 +/- 0.83), ovary (3.16 +/- 0.72), aorta (2.98 +/- 1.20), cerebellar hemisphere (2.28 +/- 1.09) and frontal lobe of the cerebrum (1.49 +/- 0.54). These data are the first to be reported on specific 5'-N activity in the human fetus. The significance of the wide range of 5'-N activity among the organs, and future aspects on the study of 5'-N activity with respect to cell differentiation, maturation, development, aging or malignant transformation were discussed.

5'-Nucleotidase↗
PubMed1981

Some properties of human erythrocyte pyrimidine 5'-nucleotidase.

In haemolysates human erythrocyte pyrimidine 5'-nucleotidase had a single optimum at pH 7.2 with CMP and 6.75 with UMP as substrate. The purified enzyme showed two pH optima at pH 6.25 and 7.2 with UMP as substrate. The enzyme was inhibited by both its products - inorganic phosphate and pyrimidine nucleoside. The inhibition by inorganic phosphate appeared to be non-competitive with Ki = 1.5 mM. Contrary to previous reports adenosine and inosine did not inhibit the enzyme.

5'-Nucleotidase↗
PubMed1986

Activities of gamma-glutamyl transferase, 5'-nucleotidase and alkaline phosphatase in human duodenal aspirate.

Duodenal aspirates were obtained before, during, and after stimulation with secretin-cholecystokinin in 26 patients whose pancreatic function was classified as normal, moderately reduced, or severely reduced. The activities of gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP), and 5'-nucleotidase (5NT) in the aggregated duodenal aspirate collected 10-40 min after stimulation showed marked overlap between the functional groups and lacked diagnostic value. For all three enzymes, the peak response occurred later in the severely impaired group than in those with normal pancreatic function. The three enzymes showed significant positive correlations with each other, and were negatively correlated with the output of trypsin and chymotrypsin and, in contrast with these proteolytic enzymes which were reduced in pancreatic disease, GGT, ALP, and 5NT all tended to increase with pancreatic disease. Contrary to a previous report, GGT did not serve as a useful index of pancreatic cancer in this study.

5'-Nucleotidase↗
PubMed1983

Electrophoretic and kinetic studies of a new mutant red cell pyrimidine 5'-nucleotidase.

Molecular characteristics of a deficient pyrimidine 5'-nucleotidase (P5N) were studied in a partially purified red cell enzyme extract. The results showed a high Michaelis constant for uridine 5'-monophosphate, an acidic shift of the optimum pH and normal heat stability. Enzyme electrophoresis using a starch gel and histidine-citrate buffer pH 7.0 showed a single band with identical mobility to that of the 'minor' band of normal enzyme. This electrophoretic pattern supports the hypothesis that P5N deficiency is, at least in some cases, a consequence of the absence of a 'major' isoenzymatic band characteristically present in normal enzyme.

5'-Nucleotidase↗
PubMed1988

Synthesis of immunoglobulin G by pokeweed mitogen- or Epstein-Barr virus-stimulated human B cells in vitro is restricted to the ecto-5'-nucleotidase positive subset.

Ecto-5'-nucleotidase (ecto-5'-NT) is believed to be a maturation marker for human B lymphocytes because its expression increases during normal development and is reduced in many patients with B cell immunodeficiencies. To determine whether this enzyme defines functional subsets of B lymphocytes, human peripheral blood B cells, separated into ecto-5'-NT positive and negative populations by using goat anti-5'-NT antibodies and the fluorescence-activated cell sorter, were compared for their ability to secrete polyclonal immunoglobulin. Both populations synthesized equivalent quantities of IgM in response to a T cell-dependent (PWM) or T cell-independent (EBV) stimulator of polyclonal immunoglobulin biosynthesis. However, ecto-5'-NT+ B lymphocytes synthesized 8- to 26-fold more IgG per cell than ecto-5'-NT- B cells. These data provide the first direct evidence that ecto-5'-NT is a marker for the functional maturation of human B cells and support the hypothesis that ecto-5'-NT deficiency in patients with hypogammaglobulinemia results from a block in B lymphocyte maturation.

5'-Nucleotidase↗
PubMed1985

Ultrastructural localization of 5'nucleotidase in human normal and malignant lymphoid cells.

5'Nucleotidase (EC 3.1.3.5), a purine pathway enzyme, occurs as a cellular ectoenzyme. Widely differing 5'N activity has been reported in different types of lymphoid cells and appears to be related to lymphocyte function, differentiation and immunological subtype. This paper reports a study on the ultrastructural distribution of 5'N in in different types of lymphoid leukemias and non-Hodgkin's lymphomas. In lymphoid leukemias, only cALL cells showed strong 5'N staining. In CLL, PLL and HCL the intensity of staining was less than in normal cells. In the NHL group, the reaction pattern was mixed. Infiltrating neoplastic cells, specially the large lymphoid cells, consistently showed very mild activity of the enzyme, whereas follicular center cells and other mature lymphocytes were characterized by moderately strong to strong 5'N activity. These results support the view that 5'N is a marker of lymphocyte cell differentiation.

5'-Nucleotidase↗