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PubMed1983

[Quantitative histochemical study of the reaction kinetics to inosine-5-monophosphate dehydrogenase and 5'-nucleotidase in cryostat sections of rat liver].

The data are presented on kinetics of histochemical enzymatic reactions demonstrating two enzymes taking part in the purine metabolism--inosine-5-monophosphate dehydrogenase (IMPD) and 5'-nucleotidase (5'-NT). It is shown that IMPD has a very weak affinity to substrate IMP (KM = 2.5 . 10(-2) M); this fact partially explains the low rate course in cryostat sections. Cytosol and membrane forms of 5'-NT have the maximum affinity to AMP (KM for membrane and cytosol forms being 1 . 10(-3) M and 2.1 . 10(-3) M, resp.). When IMP is used as a substrate, 5'-NT localized in cytosol has much lower KM as compared to the membrane form. Cytoplasmic 5'-NT is thermostable. It is suggested that a low rate of histochemical reaction demonstrating IMPD is caused by a degradation of substrate by the membrane form of 5'-NT, the Michaelis constant of which is 5 times less than that of IMPD.

5'-Nucleotidase↗
PubMed1984

Value of serum-5-nucleotidase, alkaline phosphatase and gamma-glutamyl transferase for prediction of liver metastases preoperatively in colorectal cancer.

In 133 patients laparotomized for colorectal cancer the serum-5-nucleotidase, alkaline phosphatase and gamma-glutamyltransferase were analysed preoperatively. The presence of liver metastases was established at laparotomy by palpation (prevalence 19%). The serum enzyme levels were elevated in 10-18% of patients without liver metastases and in 48-64% of patients with liver metastases. A comparison of the estimated tumor volume in the liver and the serum enzyme levels was performed. The predictive values of the three tests were computed at different reference limits. It was concluded that none of the tests used had any advantage of the other. To increase the diagnostic yield another reference limit than the normal at the laboratory can be used.

5'-Nucleotidase↗
PubMed1980

Age-dependency of lymphocyte ecto-5'-nucleotidase activity.

The activity of lymphocyte ecto-5'-nucleotidase (ecto-5'-NT) decreases with advancing age, T lymphocyte ecto-5'-NT activity begins to fall after the age of 40 and subjects in the 41 to 50, 51 to 60, 61 to 75, and 75 to 85 age ranges of life have 57, 52, 38, and 19%, respectively, of the T lymphocyte ecto-5'-NT activity of subjects under the age of 40. TG cells (suppressor cells) have 39% of the ecto-5'-NT activity of Tnon-G cells (helper cells) but the increase in numbers of TG cells that occurs with age explains only about 14% of the age-related fall in T lymphocyte ecto-5'-NT activity. B lymphocyte ecto-5'-NT activity remains stable until age 60 and subjects over 60 years of age have 42% of the B lymphocyte ecto-5'-NT activity of subjects under age 60.

5'-Nucleotidase↗
PubMed1981

Colorimetric determination of serum 5'-nucleotidase without deproteinization.

We present a sensitive colorimetric determination of 5'-nucleotidase based on the measurement of liberated phosphate by reaction with stannous chloride/molybdenum blue. No protein precipitation is required. The method is simple, sensitive, economical, and easy to use, and involves relatively stable reagents.

5'-Nucleotidase↗
PubMedDate not supplied

Human platelets 5'-nucleotidase: a cell membrane ectoenzyme with a possible regulatory role in the aggregation reaction.

The existence of a 5'-nucleotidase has been demonstrated in human blood platelets. The enzyme has a low Km (20 microM) for adenosine monophosphate. It is prevalently located on the external surface of the plasma membrane as demonstrated by the similar degradation of exogenous AMP by intact and lysed platelets. Also results of inactivation studies by means of non penetrating chemical reagents point to this conclusion. Activity is inhibited by glucosyl moieties specific lectins (e.g. Concanavalin A) with varying sensitivity in intact platelets, isolated membranes and in the solubilized form. Also micromolar concentrations of ADP inhibit the activity, possibly with a competitive pattern since this effect is much more evident at low substrate concentrations. On the basis of these results, it is suggested that this enzyme is involved in in loco adenosine production in the platelets, a process which can assume a physiological important role.

5'-Nucleotidase↗
PubMed1981

[Method of detecting alkaline phosphatase and 5-nucleotidase in histological bone sections].

Modification of the methods of Gomory, Pearce, and Reis for the detection of alkaline phosphatase and 5-nucleotidase in the bone tissue is described. The authors used fixation of the bone tissue in acetone at a temperature of 0 to 4 degrees C for 6 to 12 hours, decalcification in Grip's fluid followed by cutting in a freezing microtome of incompletely decalcified bone material and its decalcification in sections. As a result, localization of the enzyme is detected by the distribution of black sediments of cobalt sulfide.

5'-Nucleotidase↗
PubMed1981

HPLC analysis of erythrocyte pyrimidine-5'-nucleotidase inhibition by lead.

The activity of pyrimidine-5'-nucleotidase (P5N) (EC 3.1.3.5) was assayed in microsamples of rat blood using high performance liquid chromotography (HPLC). The assay is based on the measurement of enzymatically formed uridine in erythrocyte hemolysates (10-50 microliter) and produces a linear activity curve from 5 to 1000 microM/g Hb/h. Acute (22 h) administration of lead acetate ip to rats induced a dose-dependent inhibition of P5N activity in erythrocyte samples.

5'-Nucleotidase↗
PubMed1981

Studies on pyruvate kinase deficiency, pyrimidine 5-'nucleotidase deficiency and adenosine deaminase overproduction.

Using recently established ICSH recommended methods, red cell pyruvate kinases (PK) of 20 patients with PK deficiency were characterized and 7 new PK variants were found. Analysis of partially purified red cell pyrimidine 5'-nucleotidase (P5N) from a patient with P5N deficiency provided the evidence for a structural alteration of the enzyme protein. Red cell adenosine deaminase (ADA) from a patient with 40-fold increase in ADA activity associated with hemolytic anemia was purified and compared with that from normal subjects. It is most conceivable that the increased ADA activity represents increased amount of structurally normal enzyme.

5'-Nucleotidase↗
PubMed1982

Histoenzmological mapping of ATPase and 5-nucleotidase in the spinal cord and medulla oblongata of hedgehog (Paraechinus micropus).

The contribution presented deals with the distribution of adenosine triphosphatase (ATP-A) and 5-nucleotidase (AMP-A) in the spinal cord and medulla oblongata of hedgehog. The highlights of this study are: (1) AMP-A activity is stronger in neuropil than in neurons, in all the areas of spinal cord and medulla oblongata. In the nerve cells the enzyme is localized at the peripheries of the neurons, whereas the cytoplasm and nuclei are completely free from enzymatic activity. Reaction in blood vessels is quite high both in gray and white matter. (2) ATP-A activity is seen mainly at the peripheries of the neurons. The neuropil activity varies from mild to intense. Reaction in blood vessels is quite strong in all the areas. (3) Fibrous bundles and tracts are negative for both the enzymes. (4) In general, the activity of ATP-A and AMP-A is strongest in cranial nerve nuclei, irrespective of their sensory or motor nature. The distribution of these enzymes has been correlated with the functions of various nuclei of spinal cord and medulla oblongata in hedgehog, and compared with other mammals.

5'-Nucleotidase↗
PubMed1982

Pyrimidine-specific 5' nucleotidase activity in bovine erythrocytes: effect of phlebotomy and lead poisoning.

Erythrocyte pyrimidine-specific 5' nucleotidase (PY5'N) (E.C. 3.1.3.5) was measured in healthy, anemic, and lead-poisoned calves to determine whether low activity of PY5'N is associated with the propensity of cattle to develop basophilic stippling of erythrocytes. Low activity of PY5'N has been associated with basophilic stippling of erythrocytes in persons with inherited hemolytic anemia and with lead poisoning. A radiometric technique, using [14C]cytidine monophosphate as the substrate, was used to measured PY5'N activity. The erythrocytes from 4 healthy calves had much lower activity (mean of 7.1 +/- 1.6 nmols of [14C]cytidine monophosphate hydrolyzed/min/g of hemoglobin) than has been reported for human erythrocytes. The pH response curve of bovine PY5'N was similar to that of the human enzyme, with maximal activity around pH 7. Experimental hemorrhagic anemia in these calves increased PY5'N activity 6-to 7-fold, with peak activity occurring concomitantly with maximum reticulocytosis. Two of the calves were then given lead per os, and the PY5'N activity decreased within 24 hours to base-line values. In the 2 other calves not given lead, the PY5'N activity declined slowly, but did not reach base-line values after 14 days.

5'-Nucleotidase↗
PubMed1982

Cell membrane regionalization in early mouse embryos as demonstrated by 5'-nucleotidase activity.

The distribution of 5'-nucleotidase activity in pre-implantation mouse embryos is studied by means of a cytochemical method adapted from Uusitalo & Karnovsky (1977). The enzyme activity is detected, from the 4-cell stage up to the morula stage, on discrete patches of the cell membrane between blastomeres. Appropriate controls show that this distribution is not a localization artifact due to selective retention of the enzyme reaction product in the narrow interblastomeric spaces. In early blastocysts, as the blastocysts expands the enzyme activity on its lining disappears. The external surface of the trophectoderm in early blastocysts lacks any enzyme activity, whereas in late blastocysts a strong enzyme activity is detected at the embryonic trophectoderm, decreasing in intensity towards the opposite pole of the embryo. These results are compared to previous observations by other authors and the differences are mainly ascribed to differences in the cytochemical procedure employed. We conclude that during cleavage a gradual cell membrane regionalization unfolds, revealing a pattern that may be related to morphogenesis; in particular, to the localization of zonular tight junctions around the peripheral blastomeres of the morula (Izquierdo, 1977; Izquierdo, López & Marticorena, 1980).

5'-Nucleotidase↗
PubMedDate not supplied

[Distribution of thromboplastic and 5'-nucleotidase activity in human liver].

Isopycnic centrifugation of human liver tissue was carried out in sucrose density gradient. Thromboplastic activity, accompanied by 5'-nucleotidase, was mainly localized in plasmatic membranes of liver cells. The biochemical analyses of human liver tissue may be performed within 24 hrs after death.

5'-Nucleotidase↗
PubMed1983

Erythrocyte pyrimidine 5'-nucleotidase deficiency. Report of 2 new cases, with a review of the literature.

We present 2 Norwegian siblings who we believe to be the first cases of pyrimidine 5'-nucleotidase deficiency diagnosed in the Scandinavian countries. In addition to the features presented by previously published cases, our patients exhibited signs of intravascular haemolysis with haemoglobinuria and increased loss of iron in the urine. The loss of iron has made iron medication necessary from time to time. A kidney biopsy from the oldest patient revealed accumulation of iron in the epithelium of the proximal tubuli. The kidneys were considerably enlarged in both patients, but with normal function tests.

5'-Nucleotidase↗
PubMed1983

Comparison of pyrimidine 5'nucleotidase activity in erythrocytes of sheep, dogs, cats, horses, calves, and Mongolian gerbils.

Pyrimidine 5'nucleotidase (P5N) activities of erythrocytes for Mongolian gerbils, cats, dogs, sheep, horses, and calves were measured, using a radiometric technique with [14C]cytidine monophosphate as the substrate. Erythrocytes of gerbils had the highest activity [1,177.1 +/- 133.6 mU/g of hemoglobin (Hb)]. Feline erythrocytes had 327.4 +/- 204.4 mU/g of Hb. Canine erythrocytes had 148.0 +/- 19.8 mU/g of Hb. Ovine erythrocytes (44.3 +/- 20.9 mU/g of Hb), equine erythrocytes (30.0 +/- 15.9 mU/g of Hb), and bovine erythrocytes (14.1 +/- 6.9) had relatively low P5N activity. The P5N activity was approximately proportional to the reticulocyte percentage of and inversely proportional to the mean erythrocyte life span in these species.

5'-Nucleotidase↗
PubMed1983

Cytosine and uracil nucleotides in erythrocytes from two patients with pyrimidine 5'-nucleotidase deficiency.

The purine and pyrimidine nucleotides in the erythrocytes from two children with 5'-nucleotidase deficiency have been studied using HPLC-technique. The children belonged to the same Norwegian family. In addition to the conventional uracil and cytosine nucleotides relatively high concentrations of UDP-glucose, UDP-N-Ac-glucosamine, CDP-choline and CDP-ethanolamine were found.

5'-Nucleotidase↗