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PubMedDate not supplied

[5'-Nucleotidase and adenosine deaminase activity in the rat brain upon prolonged effect of low radiation doses].

The effect of combined low radiation doses (0.2-50.8 cGy) on the 5'-nucleotidase and adenosine deaminase activities in the rat hypothalamus, hippocamp and cerebral cortex during 45, 120 and 365 days was examined. It has been shown that the changes in the 5'-nucleotidase activity of the hypothalamus and hippocamp have a phase character. The direction of the changes in enzyme activity of the hypothalamus and hippocamp adenosine forming was dependent on the zone stay period and had the exactly opposite character depending on the early and prolonged stay period in the zone. 5'-nucleotidase activity was changed under the influence of mean and lesser doses with an increase of the zone stay period. No changes in the 5'-nucleotidase activity of the cerebral cortex were noted. No changes in the hypothalamic adenosine deaminase activity of rats that stayed in a zone during 45 days were revealed; under the effect of mean dose during 120 days the activity decreased and also in case of a higher dosage during one year. The adenosine deaminase activity in animal hippocamp decreased in rats only under the influence of the lesser dose, for 45-day period. The decrease in adenosine deaminase activity of the cerebral cortex that was noted under the effect of all the three doses during 45 days, the higher and mean doses during 120 days disappeared in a year.

5'-Nucleotidase↗

PubMed1975

Studies on 5'-nucleotidase activity in blood serum, tissues and liver mitochondrial fraction of normal, hypo- and hyperthyroid rats.

Clinical and experimental studies have previously shown the effect of thyroid state on the activity of non-specific phosphohydrolases. This research was undertaken to determine the influence of thyroid hormones on the activity of specific phosphohydrolase-5'-nucleotidase. The activity of 5'-nucleotidase was estimated in blood serum, tissues (liver, kidney, lung, brain) and mitochondrial fraction of liver of normal, methylothiouracil-induced hypothyroid and thyroxin-induced hyperthyroid rats of Wistar strain. The experiments have shown that the hypothyroid state induced decrease of the activity of 5'-nucleotidase in all studied materials, and on the contrary, the hyperthyroidism induced the increase of the enzyme activity. The hypothetical mechanism of the effect of thyroid hormones on the processes of feed back regulation of oxydative phosphorylation and delivery of substrates and oxygen is presented. The key role of 5'-nucleotidase in this mechanism is discussed.

Animals↗

PubMed2004

Pyrimidine 5'nucleotidase I and II activities in acute leukaemias.

BACKGROUND AND OBJECTIVE: Pyrimidine 5'nucleotidase I and II activities of peripheral mononuclear cells were studied to evaluate their role in diagnosis, assessment of therapy and follow up of remission in acute leukaemias. DESIGN AND METHODS: Blood samples were obtained from 40 untreated patients with acute lymphoblastic and myeloid leukaemia and 40 healthy controls, before the therapy and after remission. The correlation between the activity of the enzymes and the efficacy of therapy were established. The enzyme activities were measured by High-Performance Liquid Chromatography (HPLC), using the method described by Amici. For statistical analysis, Mann-Whitney U, Kruskal-Wallis and Wilcoxon methods were used. RESULTS: Before the therapy, Pyrimidine 5'nucleotidase I levels in the leukaemic group were found to be significantly elevated when compared to the control group (p<0.001). Also Pyrimidine 5'nucleotidase II levels were significantly elevated before the therapy and during remission (p<0.02 and p<0.001 respectively). The isoenzyme activities were compared in patients who were in remission, who did not respond to therapy and in patients who died during the therapy, but no significant difference was found. INTERPRETATION AND CONCLUSIONS: We concluded that, Pyrimidine 5'nucleotidase I and II activities can be used as markers for diagnosis and follow up of remission in patients with acute leukaemia. But, they can not have predictive value for prognosis.

5'-Nucleotidase↗

PubMedDate not supplied

[Effect of nitric oxide on 5'-nucleotidase activity of the membrane rafts in the smooth muscle cells].

We investigated the effect of nitric oxide on the catalytic activity of 5'-nucleotidase associated with insoluble membrane domains (rafts) of pig stomach smooth muscle. The low concentration (0.1-10.0 microM) of nitric oxide donor sodium nitroprusside led to essential increase of catalytic activity of 5'-nucleotidase. Maximal increase was observed at concentration of sodium nitroprusside of 1 microM. The enzyme's catalytic activity decreased to about control value at higher concentration of this substance. The catalytic activity of 5'-nucleotidase was also increased at presence of NaNO2, but only at high concentration (10 mM). The specific thiol-alkylating agent N-ethylmaleinimide (1-100 microM) led to essential decrease of enzyme catalytic activity. Our data shows that nitric oxide changes the AMP-ase activity of 5'-nucleotidase, that is thought to be due to direct effect of this substance on protein. We suppose, that such effect of nitric oxide could be physiologicaly important in functioning of smooth muscle.

5'-Nucleotidase↗

PubMed2006

Adenosine as a metabolic regulator of tissue function: production of adenosine by cytoplasmic 5'-nucleotidases.

Adenosine is a product of complete dephosphorylation of adenine nucleotides which takes place in various compartments of the cell. This nucleoside is a significant signal molecule engaged in regulation of physiology and modulation of the function of numerous cell types (i.e. neurons, platelets, neutrophils, mast cells and smooth muscle cells in bronchi and vasculature, myocytes etc.). As part a of purinergic signaling system, adenosine mediates neurotransmission, conduction, secretion, vasodilation, proliferation and cell death. Most of the effects of adenosine help to protect cells and tissues during stress conditions such as ischemia or anoxia. Adenosine receptors and nucleoside transporters are targets for potential drugs in many pathophysiological situations. The adenosine-producing system in vertebrates involves a cascade dephosphorylating ATP and ending with 5'-nucleotidase (EC 3.1.3.5) localized either on the membrane or inside the cell. In this paper the cytoplasmic variants of 5'-nucleotidase are broadly characterized as well as their clinical relevance. The role of AMP-selective 5'-nucleotidase (cN-I) in the heart, skeletal muscle and brain is highlighted. cN-I action is crucial during ischemia and important for the efficacy of some nucleoside-based drugs and in the regulation of the substrate pool for nucleic acids synthesis. Inhibitors used in studying the roles of cytoplasmic and membrane-bound 5'-nucleotidases are also described.

5'-Nucleotidase↗

PubMed1977

Value of alkaline phosphatase, 5'-nucleotidase, gamma-glutamyltransferase, and glutamate dehydrogenase activity measurements (single and combined) in serum in diagnosis of metastasis to the liver.

We assessed, in 98 patients with cancer, the diagnostic value of measuring serum alkaline phosphatase, 5'-nucleotidase, gamma-glutamyltransferase, and glutamate dehydrogenase activities as an aid to detection of liver metastases. All four enzymes showed diagnostic value, but 5'-nucleotidase appeared to have the greatest. It showed the lowest false-positive results (7.4%) with the highest predictive value of a positive test (85.7%) and agreement (81.3%).. gamma-Glutamyltransferase showed the lowest proportion of false-negative results (2.8%), but was the least specific 35% false-positive results). Analysis of various test combinations showed that the best agreement (77.5%) was obtained when the patients were divided into those who had no or only one abnormal test result, and those who had two or more abnormal test results. However, this was not better than the agreement for 5' nucleotidase alone (81.3%). The agreement of 5'-nucleotidase and gamma-glutamyltransferase (i.e., both tests were positive or negative) was excellent (91.4%), but such agreement included only 67% of the patients with liver metastases.

Alkaline Phosphatase↗

PubMed1990

Chicken gizzard 5'-nucleotidase is a receptor for the extracellular matrix component fibronectin.

The smooth muscle cells of chicken gizzard harbor the ectoenzyme 5'-nucleotidase. The purified enzyme was reconstituted into 3H-labeled proteoliposomes which were used as a model to study the association of a membrane protein with fibronectin. We demonstrated that the binding process between proteoliposomes and fibronectin has the qualities of a receptor-ligand interaction, i.e., is saturable and specific. In contrast to the association of fibronectin with integrins, the interaction with 5'-nucleotidase does not require divalent metal ions. Synthetic peptides containing the RGD-sequence or a monoclonal antibody interfering with binding of other receptors to the cell-binding domain of fibronectin did not abolish the interaction with 5'-nucleotidase. This indicates that the RGDS-sequence does not represent the major contact site for the AMPase and that the 5'-nucleotidase belongs to a separate class of fibronectin receptors with distinct properties as compared to the integrins.

5'-Nucleotidase↗

PubMed1989

Evidence for "low Km" and "high Km" soluble 5'-nucleotidases in human tissues and rat liver.

Two kinetically distinct purine 5'-phosphomono-esterase activities were isolated from soluble fractions of human placenta, cultured human T- and B-lymphoblasts and rat liver using AMP-sepharose chromatography. We have defined these activities as "high Km" and "low Km" 5'-nucleotidase. The relative content of "high Km" and "low Km" activities in the tissues studied ranged from 2 to 264. The optimum pH of "low Km" 5'-nucleotidases ranged from 7.4 to 9.0, Km for AMP from 7 to 15 uM and for IMP from 10 to 26 uM. ATP and ADP were inhibitors of "low Km" enzymes with the apparent Ki values of 55 to 20 uM and 8 to 20 uM for ATP and ADP, respectively. "High Km" 5'-nucleotidases had an optimum pH at 6.5, Km for IMP of 0.3 to 0.5 mM and Km for AMP of 1.0 to 9.4 mM. "High Km" enzymes were activated by ATP with A0.5 values, of 1.7 to 2.3 mM at 100 microM IMP. The data indicate that soluble "low Km" and "high Km" 5'-nucleotidases coexist in mammalian cells and fulfill different functions. These observations suggest a complex system for the regulation of AMP and IMP dephosphorylation.

5'-Nucleotidase↗

PubMed1988

Serum 5-nucleotidase and serum sialic acid in pregnancy.

Serum 5-nucleotidase enzyme activity and serum sialic acid concentrations were measured in 219 pregnant women to establish the incidence of cholestasis of pregnancy and the effect of rapid fetoplacental growth on serum sialic acid level. Serum 5-nucleotidase activity increases in diseases of the liver and obstruction of the biliary tract, whereas the level of serum sialic acid, a carbohydrate component of plasma membrane and cellular glycoproteins, rises in the presence of rapidly proliferating cells such as tumors. Serum 5-nucleotidase activity did not change between the first and the third trimesters of pregnancy. The elevation of serum 5-nucleotidase activity and of alkaline phosphatase in one case most likely indicated a cholestatic effect of pregnancy, and represented an incidence of 0.45% in the women studied. Among 201 cases, we found a graded and significant increase in the mean (+/- SD) serum sialic acid concentration with progressing pregnancy, from 1.63 +/- 0.3 mmol/L at the onset of pregnancy (five to eight weeks) to 2.06 +/- 0.49 at term; in the last stages of pregnancy, some of the values may overlap with those of cancer patients. We could not find any earlier report in the literature regarding the increase in serum sialic acid level in pregnancy.

Adolescent↗

PubMed1978

5'-Nucleotidase activity in subpopulations of rat lymphocytes.

Rat lymphocyte populations were assessed for 5'-nucleotidase activity by both biochemical and histochemical methods. Enzyme-specific activity was enriched in lymphocyte plasma membrane fractions and was higher in lymph node and spleen lymphocytes than in thymocytes. Histochemical reactions on sections of spleen and lymph node revealed strong activity in the thymus-dependent regions, periarteriolar lymphoid sheath in spleen, and paracortex in lymph node; whereas the thymus-independent regions, follicles, and germinal centers were negative. In cellular depletion experiments, with three different methods to detect 5'-nucleotidase, it was observed that the depletion of T cells, but not B cells, was accompanied by a loss of enzyme activity and a decrease in the percentage of nucleotidase-positive cells. The results suggest that, among members of the lymphocyte series, high 5'-nucleotidase activity is selectively associated with the plasma membranes of peripheral T cells in the rat.

Animals↗

PubMed1979

Ecto-5'-nucleotidase activity in T and B lymphocytes from normal subjects and patients with congenital X-linked agammaglobulinemia.

Ecto-5'-nucleotidase activity was measured in lymphocyte subpopulations isolated from normal subjects and patients with congenital X-linked agammaglobulinemia. B lymphocytes from normal subjects have at least three times more ecto-5'-nucleotidase activity than T lymphocytes. Patients with X-linked agammaglobulinemia have 56% of normal activity in their T cells, and lack a lymphocyte subpopulation high in nucleotidase activity. High activity of ecto-5'-nucleotidase may be a biochemical marker for mature surface immunoglobulin-bearing B cells.

Agammaglobulinemia↗

PubMed1979

5'-Nucleotidase levels in normal and virus-transformed cells: implications for cellular aging in vitro.

5'-Nucleotidase activity in the postnuclear supernatant of normal and SV-40 virus-transformed human embryonic lung, chick embryo, and mouse embryo fibroblasts, WI-38, IMR-90, VA-13, CEF, 3T3, and SV3T3 cells was measured. In IMR-90 and CEF cells, both of which have a limited lifespan in vitro, 5'-nucleotidase activity increased 6- and 20-fold, respectively, with increasing population doublings. However, VA-13 cells, a permanent cell line, showed no increase in this enzyme activity with progressive population doublings. 5'-Nucleotidase activity was not detectable in two other permanent cell lines, 3T3 and SV3T3 cells. Of the six cell lines tested, the conspicuous enhancement in 5'-nucleotidase activity with increasing population doublings was observed only in normal cell lines and was absent in transformed cell lines. These observations suggest a molecular mechanism which may play a role in aging of normal cells in vitro and which may involve catabolism of nucleic acids.

Adenosine Monophosphate↗

PubMed1978

Alterations in serum glycosyltransferases and 5'-nucleotidase in breast cancer patients.

We have measured sialyltransferase, galactosyltransferase, and fucosyltransferase as sell as 5'-nucleotidase in the serum of breast cancer patients. Serum sialyltransferase values in 65 normal healthy females ranged from 2.6 to 8.5 units, with a mean of 5.4. In 25 women with operable primary breast cancer, serum sialyltransferase levels were found to be between 6.2 and 15.4 units. Marked elevation of this enzyme level (range, 8.8 to 36 units) was observed in 48 patients with metastatic breast cancer. Galactosyltransferase and fucosyltransferase measurements, however, showed considerable overlap between the controls and the cancer patients. On the other hand serum 5'-nucleotidase and sialyltransferase in breast cancer patients showed very similar patterns. Thus, serum 5'-nucleotidase values in 44 normal females ranged from 11.4 to 23.2 units, whereas the levels found in 30 patients with metastasis were between 25 and 71.8 units. The tissue origin of abnormal levels of serum glycosyltransferases and 5'-nucleotidase was discussed in relation to their physiological significance as well as their role as markers for diagnosing early malignant breast neoplasm and for monitoring the extent of metastasis.

Breast Neoplasms↗

PubMed1993

Alteration in 5'-nucleotidase activities and composition of liver and brain microsomes of developing rats fed different dietary fats.

Four groups of male weanling rats were fed during three months, diets different in the nature of fats and the activity of 5' nucleotidase and fatty acid composition of brain and liver microsomes were studied. Group A were fed a standard commercial diet, group B a fat free-diet and group C and D a fat free-diet, containing respectively 10% of peanut-rapeseed oil and 10% of salmon oil. In brain and liver microsomes, 5'-nucleotidase activity increased throughout the development for all diets (except for the fat-free diet). Slight differences were found in rats fed the peanut-rapeseed oil diet compared to controls estimated at the same time. However, in animals fed the fish-oil diet, 5' nucleotidase had the highest activity in both brain and liver microsomes. Marked changes occurred in the fatty acid patterns of brain and liver microsomes among the various groups. The greatest alterations were found in the liver microsomes. In brain and liver microsomal membranes the fat-free diet induced an increase in monounsaturated fatty acids, an synthesis of eicosatrienoic acid, and a decrease in (n-6) and (n-3) polyunsaturated fatty acids. Animals fed a peanut-rapeseed oil and control diet showed similar fatty acid patterns in liver and brain microsomes. However, when rats were fed a fish-oil diet, the liver microsomal membranes were highly enriched in eicosapentaenoic and docosahexaenoic acids, and simultaneously there was a decrease in arachidonic acid. These results suggest that manipulation of the lipid environment influences 5'-nucleotidase activity by the interaction of the enzyme with specific membrane lipids.

5'-Nucleotidase↗

PubMed1994

Developmental differences in myocardial protection in response to 5'-nucleotidase inhibition.

Age-related differences in the activity of 5'-nucleotidase, an enzyme responsible for conversion of high-energy phosphates to their the diffusible precursors, may help to explain age-related differences in tolerance of global myocardial ischemia. Postischemic function and high-energy phosphate content were measured in the hearts of rabbits 7 to 10 days old (neonate), 30 to 40 days old (1 month), and 6 to 12 months old (adult). Hearts in each age group were subjected to 60 minutes of ischemia at 34 degrees C either with no cardioplegia, with unmodified St. Thomas' Hospital cardioplegic solution, or with St. Thomas' Hospital cardioplegic solution with pentoxifylline, a 5'-nucleotidase inhibitor. These groups were compared with one another and with control hearts that were continuously perfused for 1 hour. In adults, addition of pentoxifylline to St. Thomas' Hospital cardioplegic solution restored adenosine triphosphate and total nondiffusible nucleotide levels to control values and improved recovery of cardiac output and developed pressure compared with results with unmodified St. Thomas' Hospital cardioplegic solution. In contrast, biochemical and functional parameters in neonatal hearts were not affected by either unmodified St. Thomas' Hospital cardioplegic solution cardioplegia or St. Thomas' Hospital cardioplegic solution with pentoxifylline. Functional recovery in neonatal hearts subjected to unprotected ischemia was superior to that in the older age groups. In 1-month-old hearts, St. Thomas' Hospital cardioplegia improved recovery compared with recovery after unprotected ischemia, but no incremental improvement in function or high-energy stores was seen with addition of pentoxifylline. The lack of effect of pentoxifylline on neonatal hearts suggest that there is a relative deficiency of 5'-nucleotidase in this age group. This may contribute to the improved functional recovery observed in unprotected hearts. Furthermore, addition of pentoxifylline to adult hearts appears to confer the benefits of low 5'-nucleotidase activity occurring naturally in the neonate.

5'-Nucleotidase↗

PubMed1995

Demonstration of 5'-nucleotidase activity in unfixed cryostat sections of rat liver using a combined light- and electron-microscope procedure.

In the present study a technique was developed to demonstrate 5'-nucleotidase activity in unfixed cryostat sections of rat liver at the light- and electron-microscope level using a semipermeable membrane. In order to retain the ultrastructure of the unfixed material as much as possible, incubations were also performed at 4 degrees C rather than at 37 degrees C. The optimized incubation medium contained 300 mM Tris-maleate buffer, pH 7.2, 5 mM adenosine monophosphate as substrate, 30 mM cerium chloride as capturing agent for liberated phosphate, 10 mM magnesium chloride as activator and 1.5% agar. At the light-microscope level, similar localizations of 5'-nucleotidase activity were obtained when incubations were performed at 37 degrees C and 4 degrees C. Enzyme activity was present mainly at bile canalicular membranes and at sinusoidal membranes of hepatocytes; total activity was higher in pericentral than in periportal areas. Cytophotometric analyses revealed that specific formation of final reaction product (FRP) (test minus control reaction) at 37 degrees C followed a hyperbolic curve with time. A linear relationship was found between specific amounts of FRP and section thickness up to 8 micrograms. 5'-Nucleotidase activity was about three-fold higher after incubation for 30 min at 37 degrees C than at 4 degrees C. At the electron-microscope level, it was demonstrated that the ultrastructure of rat liver was rather well-preserved after incubating unfixed cryostat sections attached to a semipermeable membrane and electron-dense FRP was found at bile canalicular and sinusoidal plasma membrane of hepatocytes. The most distinct changes in ultrastructure after incubation at 37 degrees C, in comparison with that at 4 degrees C, were the appearance of multi-lamellar structures at bile canaliculi at 37 degrees C. We conclude that the present method is valid for the demonstration of 5'-nucleotidase activity in unfixed cryostat sections of rat liver at both the light- and electron-microscope levels and that hypothermic incubations improve ultrastructural morphology substantially.

5'-Nucleotidase↗

PubMed1996

Interaction of hemoglobin E and pyrimidine 5' nucleotidase deficiency.

A Bangladeshi family is described in which the genes for both hemoglobin E (Hb E) and pyrimidine 5' nucleotidase deficiency are segregating. An individual homozygous for both these conditions has a severe hemolytic anemia, whereas family members who are homozygous for Hb E are asymptomatic and those homozygous for pyrimidine 5' nucleotidase deficiency have the mild hemolytic anemia that is characteristic of this disorder. Globin-chain synthesis experiments have shown that the mechanism underlying the interaction between these two genotypes is a marked decrease in the stability of Hb E in pyrimidine 5' nucleotidase-deficient red blood cells (RBCs). It has also been found that in the enzyme-deficient RBCs in which Hb E is highly unstable, free alpha-chains, though not beta E-chains, acoumulate on the membrane. In view of the increasing evidence that the hemolysis associated with pyrimidine 5' nucleotidase deficiency results not only from an increase in the level of erythrocyte pyrimidines, but also from inhibition of the hexose monophosphate shunt activity in young erythrocytes, it is likely that the marked instability of Hb E in the enzyme-deficient cells results from oxidant damage acting on a mildly unstable Hb variant. These observations may have important implications for the better understanding of the pathophysiology of Hb E/beta-thalassemia, globally the commonest important form of thalassemia.

5'-Nucleotidase↗

PubMed1997

5'-nucleotidase and adenosine deaminase activities in blood of patients with unstable angina pectoris.

During ischaemia and hypoxia adenosine is released from cardiac cells. Adenosine is the end product of 5'-nucleotidase activity. We were interested in how this enzyme activity in plasma of patients with unstable angina pectoris, causes short-term ischaemia. 5'-Nucleotidase activity in plasma was determined using a standard diagnostic kit from Sigma. Furthermore, we studied the activity of adenosine deaminase in plasma, granulocytes, lymphocytes and erythrocytes by the methods of Hopkinson [1]. It was found that 5'-nucleotidase activity was increased by about 43% in plasma. The activity of adenosine deaminase (ADA) in plasma increased by 6%, but in granulocytes, lymphocytes and erythrocytes decreased by about 24, 19 and 10.6%, respectively. We concluded that a large increase in 5'-nucleotidase activity may be caused by activation of 5'-ectonucleotidase in blood cells by ischaemia. However, the decrease in ADA activity in blood cells may be associate with the adenosine metabolism.

5'-Nucleotidase↗