Characteristics of membrane-bound 5'-nucleotidase on human prostasomes

Examination of prostasomes, isolated from human seminal plasma, showed that there was very little remaining paranitrophenylphosphatase activity when assayed in the presence of 10 mmol/l of tartrate and 2 mmol/l of levamisole. Under these conditions it was possible to study the prostasome membrane-bound 5'-nucleotidase activity, which was unaffected by these two inhibitors. The activity was considered to be located at the external surface of the prostasome membrane and a 50-60% increase in activity was obtained by the addition of 0.05% Triton X-100. The prostasome membrane-linked 5'-nucleotidase readily hydrolysed 5'-AMP. Two other 5'-nucleoside monophosphates, 5'-IMP and 5'-GMP, were also hydrolysed, but more slowly; 2'- or 3'-AMP were practically not attacked. The prostasome membrane-linked 5'-nucleotidase obeyed Michaelis-Menten kinetics. Apparent Km for 5'-AMP was 11.2 +/- 2.1 mumol/l and Vmax 64.7 +/- 11.4 nmol/mg protein/min. These figures were somewhat changed in presence of 0.05% Triton X-100, the Km value being reduced by 30% and the Vmax value increased by 60%. Adenosine 5' (alpha, beta methylene) diphosphate (100 mumol/l), Ni2+ (10 mmol/l) and concanavalin A (20 micrograms/ml) were all potent inhibitors of the prostasome membrane-linked 5'-nucleotidase.

Hippocampal localization of 5'-nucleotidase as revealed by immunocytochemistry

The distribution of binding sites for an antibody against ecto-5'-nucleotidase was investigated in the mouse hippocampus by light microscopical immunocytochemistry. The antibody selectively labels a band corresponding to the innervation area of mossy fibre terminals within area CA3. Area CA1 as well as the dendate gyrus are negative. In area CA3 only the proximal but not the distal parts of the apical dendrites of pyramidal cells are labelled. Labelling is in the form of large dots around dendrites of pyramidal cells suggesting that mossy fibre terminals are immunopositive. In contrast, an antibody against the ubiquitous synaptic vesicle protein SV2 labels the large mossy fibre terminals as well as fine and punctate structures in the dendritic and somatic regions throughout the hippocampus. Labelled astrocytes can be found in the entire hippocampus and are frequent in the stratum radiatum and stratum oriens of the CA1 region. Immunopositive astrocytic processes can be found in association with capillary walls. Our results suggest that ecto-5'-nucleotidase may play a crucial role in the hydrolysis of AMP to adenosine at the mossy fibre synapses. Thus, at these synapses, 5'-nucleotidases could function both in completing the extracellular hydrolysis of synaptically released ATP as well as in the extracellular formation of adenosine.

Immunogold labeling and cerium cytochemistry of the enzyme ecto-5'-nucleotidase in promastigote forms of Leishmania species

We have applied both enzyme cytochemistry and immunological labeling techniques to characterize the enzyme 5'-nucleotidase (5'-Nase), at the ultrastructural level, in promastigote forms of four Leishmania species: Leishmania amazonensis, Leishmania mexicana, Leishmania donovani and Leishmania chagasi. The cerium phosphate staining was localized at the surface of the cell body, the flagellum and the flagellar pocket membranes of all the parasites studied. The immunogold labelling technique confirmed these results. In this report we localized 5'-Nase in L. chagasi and L. amazonensis which have been implicated respectively in visceral and cutaneous forms of leishmaniasis. In addition, we confirmed the localization of this phosphomonoesterase in the other two species studied. The superior quality of the images, obtained with both methodologies, confirms that these parasites possess mechanisms capable of hydrolyzing nucleotide monophosphates, and that the expression of 5'-Nase is associated with the outer surface of the plasma membrane.

Structural organization of the initial lymphatics in the monkey mesentery and intestinal wall as revealed by an enzyme-histochemical method

The structure and distribution of the initial lymphatics in whole mount preparations of the mesentery and intestinal walls of the Japanese monkey (Macaca fuscata) were studied using an enzyme-histochemical method (Kato et al., 1991, 1993). The lymphatic walls, colored dark brown by their positive 5'-nucleotidase (5'-Nase) activity, were clearly distinguished from the blood vessels (especially capillaries and arterioles) which were colored blue due to their positive alkaline phosphatase activity. The specificity and localization of both enzyme reactions were confirmed by comparative histochemical studies of the same specimen under a light microscope and scanning or transmission electron microscopes. Application of this staining method takes advantages of the overview preparation of flat membranous organs. The mesenterial area was generally lobulated in distribution with collecting lymphatics and blood vessels. At about the center of each lobule enclosed by the vessels, 5'-Nase-positive initial lymphatics assumed tubulo-saccular shapes, branching antler-like figure to form dense networks in the main lymph vascular pathway. Their apical parts revealed marked knob-like blind endings demarcated by a thin endothelial wall. No direct interconnection was recognizable between the lymphatic space and the tissue interstitium as a prelymphatic fluid pathway. In such preparations, 5'-Nase-positive lymphatic islands could be found isolated from the lymphatic network.

Detection of lymph and blood vessels in the human intervertebral disc by histochemical and immunohistochemical methods

Twenty-four intervertebral discs from the lumbar region of postmortem human subjects were investigated by immunohistochemical and histochemical methods to evaluate the pattern of blood and lymph vessels of the discus intervertebralis and surrounding tissue at different ages. Antibodies against the basement membrane component laminin, and the lectin Ulex europaeus agglutinin as a marker for L-fucose in endothelial cells, were used to make the blood vessels visible. The 5'-nucleotidase activity in lymph endothelium served as a marker for lymphatic vessels. The dorsolateral parts of the connective tissue adjacent to the discus intervertebralis were well vascularized in all age groups examined. Vessels in the outer anulus fibrosus were detected in young individuals up to 20 years of age. Vascular canals, i.e. blood vessels in the cartilage end plate, were seen up to 7 years of age. Lymph capillaries are first described here penetrating the disc and peridiscal tissue and accompanying most of the small blood vessels into the areas specified.

Effects of anemia on morphology of rat renal cortex

Information on morphological and functional effects of anemia in kidney is scarce, although this organ plays a major role in erythropoietin production, which is strongly stimulated in anemia. We undertook a morphological study of kidneys of anemic rats. Anemia was induced by X-irradiation and subsequent injection of a hemolytic drug. The most striking effects of anemia on renal morphology were damages in the proximal tubule and a volume increase of the peritubular space. These effects were evident only in the cortical labyrinth. Morphometry showed that the enlargement of the peritubular space reflected an increase of the volumes of both capillaries and interstitium. The structural changes in the cortical interstitium were associated with increased activity of the ecto-5'-nucleotidase in the fibroblasts. We suggest that hypoxia accounts for most of the observed alterations. The hypoxic proximal tubule might release the nucleotide AMP, which would be hydrolyzed to adenosine by the ecto-5'-nucleotidase in the interstitium. Adenosine has been reported to trigger the synthesis of erythropoietin and the growth of blood capillaries.

Reversibility of cholestatic changes following experimental common bile duct obstruction: fact or fantasy?

In 36 male Wistar rats extrahepatic cholestasis was induced by ligation and transsection of the common bile duct. After 1, 2 and 3 weeks of cholestasis the bile flow was restored by means of a Roux-en-Y choledochojejunostomy. Plasma levels of bilirubin, alkaline phosphatase, GOT and clotting factor X were measured weekly. Liver biopsies were taken at the time of restored bile flow as well as 3 and 8 weeks thereafter. Histochemical reaction for lactate dehydrogenase activity and Sirius Red F3BA staining were used as measure for functional liver parenchyma and collagen, respectively. Acid phosphatase, alkaline phosphatase and 5'-nucleotidase activities as well as the glycogen content were demonstrated in cryostat sections of the same biopsies. After 1, 2 and 3 weeks of common bile duct obstruction, levels of bilirubin, alkaline phosphatase and GOT significantly increased, whereas levels of clotting factor X decreased. RBF resulted in normalization of all these levels to control range. The volume density of functional parenchyma was found to be reduced to 90%, 73% and 64% of the control values following 1, 2 and 3 weeks of common bile duct obstruction respectively, returning to 96%, 94% and 88% at 8 weeks, respectively, after restored bile flow. The collagen content increased significantly during cholestasis up to 5-fold after 3 weeks of common bile duct obstruction. After restored bile flow, a slight decrease of collagen was measured in some animals but in none of the three groups a return to normal values appeared. Cholestasis induced an alteration in localization and/or activity of the three enzymes analyzed as well as a depletion of glycogen stores. All changes in activity and distribution pattern of the three enzymes, as well as the glycogen depletion during common bile duct obstruction normalised after restored bile flow was performed. However, the longer common bile duct obstruction had existed, the longer period was needed for full recovery. In conclusion, even after 3 weeks of common bile duct obstruction the parenchyma/stroma relationship grossly normalized after restored bile flow with an almost complete restoration of the parenchyma and a concomitant recovery of liver function. However, collagen once formed, did not disappear but remained as more condensed septa, which apparently did not interfere with normal function.

delta-9-Tetrahydrocannabinol inhibits cell contact-dependent cytotoxicity of Bacillus Calmétte-Guérin-activated macrophages

The effect of delta-9-tetrahydrocannabinol (delta-9-THC), the major psychoactive component of marijuana, on the capacity of Bacillus Calmétte-Guérin (BCG)-activated macrophages to lyse L929 tumor cells, Naegleria fowleri amoebae, and herpes simplex virus-infected cells was examined. Delta-9-THC inhibited tumoricidal and amoebicidal activity in a dose-related manner. Antiviral activity was decreased when mice received 25 and 50 mg/kg delta-9-THC. The cannabinoid did not directly suppress the activation of macrophages as determined by levels of 5'-nucleotidase activity and did not inhibit splenic T-lymphocytes of BCG-recipient mice from producing interferon gamma. Nomarski optics microscopy, scanning electron microscopy, and radiolabeling binding studies demonstrated that macrophages from delta-9-THC-treated mice retained their capacity to attach to their targets. These results suggest that delta-9-THC suppresses cell contact-dependent amoebicidal, tumoricidal, and antiviral activities of activated macrophages at a stage following effector cell-target cell conjugation.

Isolation and characterization of axolemma-enriched fractions from rabbit and bovine peripheral nerve

Axolemma-enriched fractions were isolated from bovine spinal accessory nerves, bovine intradural dorsal roots, and rabbit sciatic nerve by differential centrifugation and separation on a linear 10-40% sucrose (w/w) gradient. The fractions were enriched 4 to 10 fold in acetylcholinesterase, a biochemical marker for axolemma. Axolemma-enriched fractions isolated from uniformly well-myelinated fibers (bovine spinal accessory nerve) contained lower CNPase activity and higher acetylcholinesterase activity than comparable fractions isolated from variably myelinated fibers (rabbit sciatic nerve and bovine intradural roots). Separation by polyacrylamide electrophoresis showed that the molecular weight distribution of all peripheral nerve axolemma-enriched fractions was similar and ranged from 20 to over 150 kilodaltons. All axolemma-enriched fractions appeared to contain a small but variable amount of myelin-specific proteins. Based on biochemical properties, peripheral nerves containing uniformly well-myelinated fibers yield an axolemma-enriched fraction which is least contaminated with myelin-related membranes.

Staining technique for phosphatases in polyacrylamide gels

The described staining technique affords a means to detect and evaluate directly on the electrophoresis polyacrylamide gel the activity of phosphatases present in complex extracts or in purified solutions, in particular phosphatases requiring alkaline pH for optimum activity, e.g. fructose bisphosphatase, sedoheptulose bisphosphatase, and alkaline phosphatase, and 5'-nucleotidase. The method is based on a modified malachite green procedure determining orthophosphate released by the specific enzyme reactions carried out in the gel and leads to the formation of sharp blue-green-colored bands on a pale blue background. Staining intensity is proportional to the amount of Pi formed. The lower limit of phosphate detection was in the order of 0.2 nmol. This method provides a routine tool for comparative studies of biochemical properties and isozymic composition of phosphatases from diverse sources.

Co-localization of erythropoietin mRNA and ecto-5'-nucleotidase immunoreactivity in peritubular cells of rat renal cortex indicates that fibroblasts produce erythropoietin

In adults, the kidneys are the major site of production of the glycoprotein hormone erythropoietin (EPO), but the type of renal cell producing EPO has not yet been identified. In the present study we used non-radioactive in situ hybridization with a digoxigenin-labeled cRNA probe to localize cells that produce erythropoietin (EPO) in kidneys of anemic rats. Cryostat sections from both native and perfusion-fixed tissue were used. Cells containing EPO mRNA were found exclusively in the peritubular space of the renal cortex. Using high-resolution interference contrast optics, we found that cells expressing EPO mRNA were not associated with the lumina of peritubular capillaries but rather were located in the angles between adjacent tubules or between tubules and vessels. These spaces are predominantly occupied by resident interstitial fibroblasts and by their cytoplasmic processes. To further identify the type of cell containing EPO mRNA, a double-labeling protocol was established that permitted on the same tissue section both in situ hybridization for EPO mRNA and parallel immunolabeling of ecto-5'-nucleotidase (5'-Nu), a surface marker of peritubular interstitial fibroblasts. The combined labeling technique revealed that a clear majority of cells expressing EPO mRNA also displayed staining for anti-5'-Nu. Staining for EPO mRNA was localized in central perinuclear parts of the interstitial cells, whereas 5'-Nu label was present on the cell surface, including the cytoplasmic processes. These data indicate that peritubular fibroblasts are cellular sites for production of erythropoietin.

Histochemical detection of glycogen phosphorylase activity as parameter for early ischemic damage in rat heart

In the present study we have investigated whether enzyme histochemical parameters can be applied to detect early ischemic damage in rat heart after ischemia without restoration of the blood flow. Ischemia was induced by incubating heart fragments for 0, 10, 20, 30, 60, 120 and 240 min at 37 degrees C. The activity and localization of the following enzymes was studied in unfixed cryostat sections using quantitative histochemical methods: lactate dehydrogenase, creatine kinase, succinate dehydrogenase, phosphofructokinase, acid phosphatase, 5'-nucleotidase and glycogen phosphorylase. Moreover, the ultrastructure of the tissue was studied with special attention to the appearance of flocculent densities in mitochondria, which can be seen as a sign of irreversible cell damage. It was shown that glycogen phosphorylase activity in rat heart decreased after short periods (30 min) of in vitro ischemia, whereas all other enzymes studied were not decreased up to 240 min, with the exception of lactate dehydrogenase and phosphofructokinase activities which were diminished only at 240 and 120 min of ischemia, respectively. Some reaction product was found after incubating for 5'-nucleotidase activity in the absence of substrate, indicating the presence of endogenous substrate(s). This endogenous substrate disappeared from the myocytes after 20 min of ischemia. It is assumed that AMP and/or other phosphate-containing compounds play an essential role in the activation of glycogen phosphorylase. Significant reduction of glycogen phosphorylase activity is correlated with the irreversible stage of damage of myocytes as judged from the ultrastructure.

Aberrant crypts in human colonic mucosa: putative preneoplastic lesions

Aberrant crypts are recognized in methylene blue-stained, unsectioned, colonic mucosa by their increased size, elliptical lumenal opening, thicker epithelial layer, and increased pericryptal region. Aberrant crypt foci in rodents are observed as early as 2 weeks and for at least 9 months after a single dose of carcinogen, have a distribution that parallels that of tumors, and have an increased number of aberrant crypts per focus with time after the carcinogen dose. The ability to quantify these lesions in the entire colon of rodents in less than an hour suggests that aberrant crypts may provide a highly efficient in vivo bioassay for colon carcinogens. Since aberrant crypt foci appear to be the earliest identifiable putative precursors of colon cancer, they represent lesions that can be characterized further for the earliest genetic and biochemical alterations. In F344 rats, we have demonstrated that aberrant crypts have multiple histochemically-detectable enzyme alterations. Using similar techniques, we were the first to demonstrate aberrant crypts in unsectioned human mucosa. After embedding and sectioning, these microscopic aberrant crypts resemble rare lesions described earlier in the literature after extensive serial sectioning. In rats and humans, aberrant crypts may be histologically normal or display varying degrees of dysplasia and histochemically-detectable altered enzyme activities. These putative, preneoplastic lesions should reveal early changes that precede colon cancer and ways to alter their progression.

[A comparative study of the ectophosphatase activity in different subpopulations of tumor cells]

Activities of ectophosphatases (alkaline phosphatase, 5'-nucleotidase and ecto-ATPase) from different subpopulation of lymphoma NKLy and ovary tumor of rats were investigated. A strong positive correlation has been shown between these activities in different subpopulations. A negative correlation between proliferative activity and activities of ectophosphatases was determined. The role of ectophosphatases in cell proliferation is discussed.

An in vitro method for comparing the efficacy of two preservation solutions in one canine liver using the 5'-nucleotidase assay

The activity and localization of the plasma membrane-bound enzyme 5'-nucleotidase (5'-NT) in liver tissue are sensitive parameters of ischemic damage. The value of 5'-NT as a marker of liver graft viability was studied in relation to liver preservation. In six mongrel dogs, the main right and left branches of the portal vein were cannulated and flushed separately in situ with cold University of Wisconsin (UW) solution and Euro-Collins (EC) solution, respectively. After hepatectomy, the right and left liver lobes were split and stored at 5 degrees C in either of the two solutions. 5'-NT activity was demonstrated in cryostat sections of liver tissue using the lead salt method. After 48 h of storage in EC solution, the 5'-NT score had decreased to 31% +/- 16% (n = 6), whereas in UW solution the 5'-NT score was 76% +/- 10% (n = 6). Significantly (P < 0.05) higher 5'-NT scores were also found after 24-h and 72-h preservation times in UW versus EC solutions. This result is in keeping with the higher preservation tolerance of liver grafts preserved in UW solution. The 5'-NT assay was studied in relation to graft function in orthotopic liver transplantation experiments in dogs. All dogs with liver grafts preserved in UW solution for 24 h (n = 4) and 48 h (n = 3) survived (> 5 days). Pretransplant 5'-NT scores ranged from 61% to 100%. The 72-h-preserved livers (n = 5) did not show life-supporting function.(ABSTRACT TRUNCATED AT 250 WORDS)

A combined immunodeficiency with oligoclonal CD8+, V beta 3-expressing, cytotoxic T lymphocytes in the peripheral blood

The diagnosis severe combined immunodeficiency was made in a male infant at the age of 18 wk. Known causes of severe combined immunodeficiency were excluded. The activity of total 5'-nucleotidase (E.C. 3.1.3.5) in the PBMC was found to be strongly decreased. Analysis of the peripheral blood revealed a lymphocytosis, mainly of CD8+ T cells. These lymphocytes expressed high levels of CD29, CD38, CD45RA, and MHC class II molecules but no CD25, CD26, CD27, or CD28 Ag. The cells proliferated poorly to all T cell stimulants tested and no helper activity for IgM secretion could be induced. In contrast to the poor proliferative responses, high levels of TCR-induced cytolytic activity, without lymphokine-activated killer-cell outgrowth, were induced by CD3 mAb. Analysis of TCR-beta gene rearrangements indicated that two clonal populations constituted the majority of the E-rosette+ peripheral blood fraction. Moreover, the vast majority of the CD8+ cells were found to react with a mAb to V beta 3. Polymerase chain reaction on cDNA from peripheral blood cells with primers that amplify TCR V beta elements showed, in agreement with the fluorescence data, an overrepresentation of V beta 3 but absence of usage of approximately 50% of the other V beta elements. Thus, in a severe combined immunodeficiency patient, CD8+ T cells with limited T cell receptor usage and restricted effector functions were found. The observed alterations in the 5'-nucleotidase levels may be secondary to the outgrowth of this population.

Enzymatic activity and in vivo distribution of 5'-nucleotidase, an extracellular matrix binding glycoprotein, during the development of chicken striated muscle

The ecto-enzyme 5'-nucleotidase isolated from chicken gizzard has previously been shown to be a potent ligand of two glycoproteins of the extracellular matrix, namely fibronectin and laminin. Using immunofluorescent labeling techniques we observed that 5'-nucleotidase codistributed with laminin during the development of chicken striated muscle. In contrast, ecto-5'-nucleotidase was only faintly detectable on cells surrounded by a matrix expressing high levels of fibronectin. This distribution pattern distinguished 5'-nucleotidase from the pluripotent extracellular matrix receptors, chicken beta 1-integrins, which are expressed equally well in muscle and connective tissue. In addition, the specific activity of striated muscle ecto-5'-nucleotidase was stable during development and increased markedly posthatching. At each age considered, this specific activity corresponded to an 80-kDa enzyme which was inhibited by alpha,beta-methyleneadenosine diphosphate or by a monoclonal antibody directed against the smooth muscle isoform of the enzyme. Previous in vitro studies have revealed that 5'-nucleotidase is involved in the spreading of various mesenchyme-derived cells, such as chicken embryonic fibroblasts and myoblasts, on a laminin substrate. A prerequisite to examining a potential in vivo role for 5'-nucleotidase as an extracellular matrix ligand was to study its distribution. In adult muscle, 5'-nucleotidase displayed a more restricted distribution than in embryo. Results show that, in vivo, 5'-nucleotidase is revealed by immunofluorescent labeling using poly- and monoclonal antibodies to chicken gizzard 5'-nucleotidase in two structures, the costameres and myotendinous junctions, which are closely related to the focal adhesion sites observed in cell culture.

Preparation of right-side-out plasma membrane vesicles from Penicillium cyclopium: a critical assessment of markers

A plasma membrane fraction was obtained by the combined use of differential centrifugation and aqueous polymer two-phase partitioning techniques. Vanadate-inhibited ATPase and glucan synthase activities were highly enriched in this fraction, although the presence of ATPase activity which was not inhibited by vanadate, nitrate, molybdate, anyimycin A or azide was also detected. Other intracellular membrane marker activities were present at very low or undetectable levels. A further separation step using Percoll density gradient centrifugation resulted in the separation of a fraction which exclusively contained vanadate-inhibited ATPase activity, and was enriched with silicotungstic-acid-staining membrane material. Latency tests performed on the plasma membrane markers showed that the membrane vesicles were in the right-side-out orientation.

An extended developmental study of ?-glutamyltranspeptidase in rat liver plasma membranes: identification of specific patterns of changes in activity in the adult as well as the neonatal state

Homogenates and plasma membranes were isolated from the livers of male Fischer 344 rats ranging in age from 19 hr to 92 days postnatal. These plasma membranes exhibited comparable levels of purity: protein yields were 2-2.5%; relative specific activities of 5'-nucleotidase and ouabain-sensitive Na+/K(+)-ATPase were from 8-11 and from 12-19, respectively. 5'-nucleotidase and ouabain-sensitive Na+ K(+)-ATPase displayed distinct and different developmental patterns. The activity of gamma-glutamyltranspeptidase was found to be at exceptionally high levels in isolated plasma membranes immediately after birth and to decline precipitously thereafter achieving and maintaining low levels from days 3-21 postnatal. Liver plasma membrane gamma-glutamyltranspeptidase activity was observed to increase 9.2 fold from this low point, first rising on day 21, peaking on day 40 and returning to low levels by day 56. From day 56 day to 92 postnatal, gamma-glutamyltranspeptidase activity was expressed at a uniformly low level but a level 2 fold higher than that preceding the rise at day 40. The hormone determinants of these developmental changes in gamma-glutamyltranspeptidase activity are discussed.

Superoxide dismutase enhances ischemia-induced reactive hyperemic flow and adenosine release in dogs. A role of 5'-nucleotidase activity

To test the hypothesis that 5'-nucleotidase activity during ischemia is attenuated by oxygen-derived free radicals, we measured ischemia-induced reactive hyperemic flow, adenosine release, and 5'-nucleotidase activity in dogs (n = 62). A 1-minute occlusion of the coronary artery caused reactive hyperemic flow (307 +/- 5 versus 92 +/- 1 ml.100 g-1.min-1 at baseline) with increased release of adenosine (14.4 +/- 1.4 versus 0.4 +/- 0.1 nmol.100 g-1.min-1 at baseline). Superoxide dismutase augmented (p less than 0.001) both peak coronary blood flow (333 +/- 6 ml.100 g-1.min-1) and repayment (436 +/- 12 versus 320 +/- 7 ml/100 g in the untreated group). Adenosine release during reperfusion was augmented (22.7 +/- 1.9 nmol.100 g-1.min-1, p less than 0.001), and 8-phenyltheophylline completely abolished the enhanced reactive hyperemia. Enzymatic assay of 5'-nucleotidase activity revealed that the administration of superoxide dismutase increases ecto-5'-nucleotidase activity in ischemic myocardium. When an inhibitor of ecto-5'-nucleotidase, alpha, beta-methyleneadenosine 5'-diphosphate, was administered, the effects of superoxide dismutase were completely abolished. Thus, we conclude that 1) the augmentation of reactive hyperemic flow caused by superoxide dismutase is attributed to the enhanced release of adenosine and 2) the enhanced release of adenosine over the untreated controls is attributed to the protection of ecto-5'-nucleotidase activity during ischemia.

Relation of 5'-nucleotidase and phosphatase activities with immunophenotype, drug resistance and clinical prognosis in childhood leukemia

Ecto-5'-nucleotidase (ecto-5'NT) catalyzes the extracellular dephosphorylation of nucleotides like IMP. Cytoplasmic 5'NT (cyto-5'NT) and non-specific (e.g. acid- and alkaline) phosphatases (AP) regulate the intracellular degradation of nucleotides. High NT and AP activities might cause a resistance to the thiopurines 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG). We studied the relation between these enzymes and immunophenotype, drug resistance and prognosis in 77 children with acute lymphoblastic leukemia (ALL). Enzyme activities were assessed radiochemically; in vitro drug resistance was measured with the MTT assay. AP activities were higher in T-ALL and B-ALL than in precursor B-ALL. Cyto-5'NT activity was very low in all phenotypes and accounted for a significant proportion of total IMPase activity only in the very immature CD10- c mu- precursor B-ALL. CD10+ ALL cases with high ecto-5'NT activities showed a trend (p = 0.065) for a lower probability of continuous complete remission than those with a low activity. Ecto-5'NT activity was not related to in vitro drug resistance to 6-TG. A weak correlation was found between in vitro 6-TG resistance and cyto-5'NT and AP activities. We conclude that high ecto-5'NT activities do not cause a resistance to 6-thiopurines in childhood ALL. Some patients have high cyto-5'NT and AP activities associated with 6-thiopurine resistance.

5'-nucleotidase: a new marker for striosomal organization in the rat caudoputamen

The distribution of the adenosine-producing ectoenzyme 5'-nucleotidase was studied by means of a histochemical lead technique in the caudoputamen of normal adult rats and of rats in which injections either of 6-hydroxydopamine in the medial forebrain bundle or of ibotenic acid in the caudoputamen had been made 1-3 weeks previously. The patterns of striatal 5'-nucleotidase activity in these animals were compared in serial sections to the patterns of calbindin-D28k immunoreactivity and of 3H-naloxone ligand binding, which respectively mark the known matrix and striosome (patch) compartments of the caudoputamen. In the normal rats, 5'-nucleotidase activity was differentially concentrated in striosomes, where it produced a dense staining of the neuropil. The enzymatic staining followed a striosomal distribution in all but the caudal caudoputamen. Within the striatal matrix, 5'-nucleotidase staining also observed a lateromedial density gradient. Depletion of the dopamine-containing nigrostriatal innervation of the caudoputamen with 6-hydroxydopamine did not alter the striosomal selectivity of 5'-nucleotidase activity. Destruction of intrastriatal neurons by ibotenic acid led to a strongly 5'-nucleotidase-positive gliosis within the resulting necrotic region. Elsewhere in the caudoputamen, the enzyme's striosomal distribution was not detectably altered. We conclude that 5'-nucleotidase histochemistry provides an advantageous tool for detecting the striosomal architecture of the rat's caudoputamen. Moreover, 5'-nucleotidase is prominently associated with glial membranes in the central nervous system, so that the concentration of this enzyme in striosomes could mark these as sites of selective glial populations within striatum. These properties and actions of 5'-nucleotidase in purinergic neurotransmission and in neuroadhesion may contribute to the specialized functions of striosomes and matrix.

Ecto-5'-nucleotidase is associated with cholinergic nerve terminals in the hippocampus but not in the cerebral cortex of the rat

The extracellular catabolism of exogenously added AMP was studied in immunopurified cholinergic nerve terminals and in slices of the hippocampus and cerebral cortex of the rat. AMP (10 microM) was catabolized into adenosine and inosine in hippocampal cholinergic nerve terminals and in hippocampal slices, as well as in cortical slices. IMP formation from extracellular AMP was not detected. alpha, beta-Methylene ADP (100 microM) inhibited almost completely the extracellular catabolism of AMP in these preparations. The relative rate of catabolism of AMP was greater in hippocampal slices than in cortical slices. AMP was virtually not catabolized when added to immunopurified cortical cholinergic nerve terminals, although ATP could be catabolized extracellularly under identical conditions. The comparison of the relative rates of catabolism of exogenously added AMP, calculated from the amount of AMP catabolized after 5 min, in hippocampal cholinergic nerve terminals and in hippocampal slices revealed a nearly 50-fold enrichment in the specific activity of ecto-5'-nucleotidase upon immunopurification of the cholinergic nerve terminals from the hippocampus. The results suggest that there is a regional variation in the subcellular distribution of ecto-5'-nucleotidase activity in the rat brain, the ecto-5'-nucleotidase in the hippocampus being closely associated with the cholinergic nerve terminals, whereas in the cerebral cortex ecto-5'-nucleotidase activity seems to be located preferentially outside the cholinergic nerve terminals.

Lipid peroxidation and myocardial vulnerability in hypertrophied SHR myocardium

In a comparison using age-matched Wistar-Kyoto rats (WKY), 16-week-old male spontaneously hypertensive rat (SHR) hearts were examined histologically and biochemically on the first and fourth day after administration of 20 mg/kg doxorubicin in order to examine whether membrane abnormalities in hypertrophied SHR myocardium are caused by lipid peroxidation. Morphological examination of the SHR revealed focal myocytolysis on the first day and severe cardiomyopathy involving diffuse myocytolysis and vacuolar degeneration in the left ventricle on the fourth day. The activity of a membrane-related enzyme, Na+/K(+)-ATPase, was already lower in control SHR than that of control WKY and was lower in both SHR and WKY than in the respective saline groups on the first day after administration, whereas the enzyme activity in the doxorubicin-treated SHR was not significantly different from that of the treated WKY. A thiobarbituric acid-reactant substance, a lipid peroxidation marker, was significantly higher in treated SHR than it was in the treated WKY on the first day. Furthermore, in comparison with WKY, alpha-tocopherol in the left ventricle in SHR was significantly lower on the fourth day after administration. These results show that a proneness to lipid peroxidation in the membrane system is closely associated with severity of doxorubicin-induced cardiomyopathy in SHR and suggests that membrane lipid peroxidation may cause a higher degree of vulnerability in hypertrophied SHR myocardium.

Effects of fish and safflower oil feeding on subcellular glucose transporter distributions in rat adipocytes

Effects of fish oil feeding on glucose transport systems and cell size in rat adipocytes were examined and compared with those of safflower oil or carbohydrate feeding under isoenergy intake conditions. Glucose transport activity was assessed by measuring 3-O-methyl-D-glucose transport. The concentration of erythrocyte type glucose transporter (GLUT-1) and muscle/fat type transporter (GLUT-4) was measured by immunoblotting. The amount of each transporter in intact cells was estimated by the amount of transporter and protein of each membrane fraction and by the recovery of marker enzymes. In cells from safflower-fed rats compared with those from carbohydrate-fed rats, insulin-stimulated glucose transport activity per cell decreased to 51% after a 1-wk feeding, and cell size increase became larger with these effects and continued for at least 4 wk. At 1 wk of feeding, GLUT-1 and GLUT-4 per cell in plasma membrane from insulin-treated cells decreased to 62 and 35%, respectively, with concomitant transporter decreases in the low-density microsome fraction. In cells from high-fish oil-fed rats in which two-thirds of safflower oil was replaced by fish oil, when compared with those from safflower oil-fed rats, insulin-stimulated glucose transport activity increased 1.7-fold after 1 wk of feeding with concomitant cellular GLUT-1 and GLUT-4 increases, but its effect declined thereafter. Parallel with this time course, cell size increase was smaller after 1 wk, but this effect also declined thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Species differences in adenosine metabolic sites in the heart

5'-Nucleotidase and purine nucleoside phosphorylase, two key enzymes in nucleoside metabolism, have been localized electronmicroscopically in left ventricular myocardium of the human, dog, pig, rabbit, guinea pig and rat. Ectonucleotidase activity was present in all species at the plasma membrane of pericytes. Reactive endothelial cells in the microcirculatory bed were restricted to those covering resistance arterioles. Cardiomyocytes were reactive only in the rat. Purine nucleoside phosphorylase was localized uniformly in the vascular endothelium of all species. The strongest activity was seen in the pericytes of guinea pig, rat and dog. Pericytes of rabbit and pig were virtually unreactive, whereas a minority of cells in human samples were positive. Cardiomyocytes were unreactive in all species. These variations in the distribution pattern of adenosine metabolic sites may have definite consequences for disposal and recovery of adenylates and their breakdown products in ischaemia and for the effects to be expected from interference with nucleoside transport inhibition.

Effects of ursodeoxycholic acid on liver function in patients with cystic fibrosis and chronic cholestasis

Ursodeoxycholic acid, 10 to 20 mg/kg per day, was administered for 1 year to 22 patients with cystic fibrosis and chronic cholestasis, resulting in significantly improved liver enzyme values. However, evidence of cholestasis continued, as shown by the pattern of alkaline phosphatase isoenzymes.

Cytochemical and stereological analysis of rat cortical astrocytes during development in primary culture. Effect of prenatal exposure to ethanol

This study has investigated the effect of prenatal alcohol exposure on the qualitative and quantitative ultrastructure of proliferating and differentiated astrocytes in primary cultures as well as on the cytochemical activity of several subcellular phosphatase markers, including acid phosphatase, uridine diphosphatase, thiamine pyrophosphatase, 5'-nucleotidase and glucose-6-phosphatase. The astrocytes were obtained from 21-day-fetuses of both control and alcohol-fed rats. Our results show that several cell components, such as mitochondria, rough endoplasmic reticulum and lysosomes, exhibit qualitative and/or quantitative ultrastructural changes during the process of astrocyte maturation. In some cases these morphological changes are accompanied by variations in the cytochemical activity of enzymes located in these and other cell components, suggesting that these enzymes, and therefore the functional state of these organelles, are modulated during astrocyte development. When prenatally exposed to ethanol, both proliferating and differentiated astrocytes showed striking ultrastructural alterations compared with controls, including an increment of lysosomes as well as a decrease in the values of stereological parameters relative to mitochondria, rough endoplasmic reticulum and Golgi apparatus. Cytochemical analysis of these cells indicates that prenatal exposure to ethanol decreased the activities of all the enzymes tested, except for acid phosphatase, which was increased in both groups of treated astrocytes. These results suggest that prenatal exposure to ethanol could affect astrocytes during development in two different but probably complementary ways: a) by causing a delay in astrocyte maturation and, b) by inducing a direct toxic effect on these cells.

[Changes in the activity of 5'-nucleotidase and protein kinase of the hepatic plasma membrane depending on the dose rate in x-ray irradiation of rats]

In studying the effect of X-irradiation of rats with a dose of 4 Gy at different dose rates (96 and 4.6 cGy/min) the authors have revealed an increase in 5'-nucleotidase activity at a high dose rate (the first 24 h following irradiation) and a decrease in protein-kinase activity at a low dose rate (on days 3 and 7). The preinjection of alpha-tocopherol prevents the changes observed.

Membrane vesicles from brown adipose tissue: a tool for the study of amino acid transport. The case of L-alanine

A density gradient method is used to isolate membrane vesicles from brown adipose tissue. These respond to changes in osmolarity and show the classical overshoot pattern when L-alanine uptake is assayed. Transport is shown to be effected by two components: a linear (Kd = 0.498 min-1) and Na(+)-dependent saturable component (Km = 2.3 mM) and a Vmax = 19.9 pmol/micrograms protein.min). This pattern is similar to that shown by cells isolated from brown adipose tissue.

Calcium transport and Ca(++)-ATPase activity in spermatozoal plasma membrane vesicles of nifedipine-administered guinea pigs

Spermatozoal plasma membrane vesicles isolated from distal portion of the epididymis and vas deferens were found to contain Ca(++)-activated ATPase and calcium transport activities. Nifedipine was administered at two different doses (1.0 and 2.5 mg/kg b.w./day) and the effect was observed for both short- (4 week) and long-term (12 week) period. The cellular ionic calcium content and Ca(++)-ATPase activity were observed to be enhanced in the drug-treated animals. The recovery studies carried out after 4 and 6 weeks of withdrawal of the drug treatment exhibited partial to complete restoration of observed changes. The stimulatory rather than inhibitory effect of Nifedipine, a specific calcium channel blocker, on calcium uptake may suggest that voltage-sensitive calcium channels may be lacking in guinea pig spermatozoa. The stimulatory effect of the drug is speculated to be either by inhibition of Na(+)-Ca++ antiporter or G-protein activated agonistic effect or probably due to altered physicochemical properties of the drug-treated sperm plasma membranes.

[Sensitivity to mouse toxin and level of macrophage 5-nucleotidase activity]

It is shown that immunomodulator of bacterial origin salmozan causes alternations of sensitivity to mouse toxin in mice CBA. A correlation exists between the sensitivity to mouse toxin and the level of 5-nucleotidase of peritoneal exudate macrophages.

The distribution of A1 adenosine receptor and 5'-nucleotidase in pig brain cortex subcellular fractions

Pig brain cerebral cortex was subfractionated by isopycnic centrifugation in sucrose gradients. In each subfraction the content of the agonist [3H]R-PIA binding, the activity of adenosine metabolizing enzymes (5'-nucleotidase and adenosine deaminase) and the activity of membrane marker enzymes were determined. The fractions were also examined by electron microscope. In general, the results suggest a widespread distribution of A1 adenosine receptors in membranes from different origins. Marker enzyme profile characterization indicated an enrichment of A1 adenosine receptor in pre-synaptic membranes isolated from the crude synaptosomal fraction (P2B subfraction) as well as in membranes of glial origin such as myelin. The receptor is also present in the endoplasmic reticulum and in membranes isolated from the microsomal fraction that seem to have a post-synaptic origin (P3B). In subfractions having a high content of adenosine receptor the equilibrium binding parameters were obtained as well as the proportion of high- to low-affinity sites. From the values of the equilibrium constants it was not possible to find differences between the receptor in the different subfractions. Analysis of the affinity state distribution showed a diminished percentage of high-affinity sites in fraction P3A, which can be accounted by the existence of myelin membranes; in contrast the percentage of high-affinity states was higher in P2 and P3B, indicating that in these fractions the receptor is present in synaptosomal membranes. The close correlation shown between the enzyme 5'-nucleotidase specific activity and the specific ligand binding distributions led us to postulate an important role for the enzyme in the regulation of adenosine action in pig brain cortex.

Different localization of inositol 1,4,5-trisphosphate and ryanodine binding sites in rat liver

The distribution of inositol 1,4,5-trisphosphate and ryanodine binding sites between plasma membrane, microsomal, and mitochondrial fractions of rat liver were compared. IP3 bound mostly to the plasma membrane fraction (Kd = 6 nM; Bmax = 802 fmol/mg protein). Some IP3 binding sites were also present in the microsomal and mitochondrial fractions (Kd = 2.5 and 2.9 nM; Bmax = 35 and 23 fmol/mg protein respectively). The possibility that these binding sites are due to contamination of the fractions with plasma membrane cannot be excluded. Binding of IP3 to the plasma membrane was inhibited by heparin but not by either caffeine or tetracaine. High-affinity ryanodine binding sites were present mostly in the microsomal fraction (Kd = 13 nM; Bmax = 301 fmol/mg protein). Lower affinity binding sites were also found to be present in the mitochondrial and plasma membrane fractions. Binding of ryanodine to the microsomal fraction was inhibited by both caffeine and tetracaine but not by heparin. These data demonstrate that IP3 and ryanodine binding sites are present in different cellular compartments in the liver. These differences in the localization of the binding sites might be indicative of their functional differences.

Effect of Calcium Concentration on Survival, Proliferation and Activities of Alkaline Phosphatase, 5'-Nucleotidase, .GAMMA.-Glutamyltransferase and Lactate Dehydrogenase of Adult Rat Hepatocytes Cultured

Mature rat hepatocytes were cultured on collagen coated dishes in serum-free alpha-modified Eagle's minimum essential medium containing 0.1 microM insulin, 0.1 microM dexamethasone, 10 mM pyruvate and Ca2+ at concentrations of 0-2 mM. Survival of nondivided cells was best in medium containing 2 mM Ca2+. Proliferation during 5-day culture was greatest with 0.4 mM Ca2+, but DNA synthesis was scarcely affected by the concentration of Ca2+. Both the activities of alkaline phosphatase, 5'-nucleotidase, gamma-glutamyltransferase and lactate dehydrogenase and the number of cell nuclei of cultures in 0.1 mM and 2 mM Ca2+ media were assayed over a 5-day period, and their activities were calculated as enzyme activities per unit number of cell nuclei. Alkaline phosphatase activity increased rapidly during the first day of culture in both media, and its activity in 0.1 mM medium was higher than that in 2 mM medium after culture for 3 days. The activity of 5'-nucleotidase became higher in 0.1 mM medium than in 2 mM medium from day 2 and was maximal on day 3 in both media. gamma-Glutamyltransferase activity increased and lactate dehydrogenase activity decreased with time in culture, both activities showing no appreciable difference in the two media.

Natural killer cells lack ecto-5'-nucleotidase

Ecto-5'-nucleotidase (ecto-5'-NUC, EC 3.1.3.5., CD73) is a plasma membrane enzyme, which catalyzes the hydrolytic dephosphorylation of purine nucleotides to the corresponding nucleosides so that they can pass through the plasma membrane. The distribution of ecto-5'-NUC is heterogeneous, but all blood mononuclear cell (BMC) subpopulations investigated until now have had ecto-5'-NUC activity. Purified natural killer (NK) cells were prepared by fluorescence-activated cell sorting of CD16-positive cells (purity 94%). In purified NK cells the ecto-5'-NUC activity was less than 1 U/10(6) as estimated by a radioisotope method. Using a cytochemical assay, the proportion of cells with activity was less than 1%. The most likely explanation is that NK cells have no ecto-5'-NUC activity and that the very small ecto-5'-NUC activity observed in this study was caused by contaminating non-NK cells. NK cells thus constitute the only BMC subset known without ecto-5'-NUC activity.

Enzyme-histochemical study on the fine distribution of the intramural lymphatics at the ileocecal junction of the monkey intestine

The fine distribution of the intramural lymphatics at the ileocecal junction of the monkey intestine, especially in the lamina propria of the ileocecal valve, was examined by light and electron microscopy using enzyme-histochemical staining. The distinction between the lymphatics and the blood vessels was made by light microscopy on cold glycol methacrylate resin (JB-4) sections using 5'-nucleotidase (5'-Nase)-alkaline phosphatase (ALPase) double staining. The lymphatics were found to show strong 5'-Nase activity and to comprise irregularly shaped vessels or spaces. The central lymphatic vessels (central lacteals) in low villi were seen to lie deep within the ALPase-positive subepithelial capillary network. In the ileum side of the ileocecal junction, the 5'-Nase-positive lymphatics were seen both in the superficial layer and the deep layer of the lamina propria. On the contrary, in the cecum side the mucosal lymphatics were less numerous in the superficial layer and were distributed mainly in the deep layer near the lamina muscularis mucosae. These lymphatics ran through the lamina muscularis and merged into the lymphatic network in the submucosa. The submucosal lymphatics communicated with each other at the ileocecal junction and formed a well-developed network. Collecting lymphatics with valves were also seen near the tunica muscularis (sphincter muscle) in the deep submucosa. These lymphatics traversed the muscle layer and drained into the subserosal lymphatics.

Hepatic organelle pathology in dogs with congenital portosystemic shunts

Diversion of portal blood in congenital portosystemic shunts (CPSS) results in liver atrophy and passage of toxins into the systemic circulation causing hepatic encephalopathy. In some dogs, there is indirect evidence for hepatic insufficiency, but histologic findings are equivocal. This study determined whether hepatocyte integrity in PSS is comprised at a subcellular level using analytical subcellular fractionation of liver biopsies. Six dogs with CPSS had hypoproteinemia (6/6), increased serum alkaline phosphatase (6/6) and alanine aminotransferase (4/6) activity, hypocholesterolemia (6/6), and decreased blood urea (2/6). Liver biopsy specimens had increased activities (mU/mg protein) of alkaline phosphatase (17.9 +/- 10.1; controls 5.1 +/- 5.3: P less than 0.01), but not of other plasma membrane enzymes. There were increased activities of endoplasmic reticular (neutral alpha-glucosidase: 1.67 +/- 0.7; controls 0.86 +/- 0.2: P less than 0.01) and lysosomal enzymes (N-acetyl-beta-glucosaminidase: 12.6 +/- 2.3; controls 6.24 +/- 2.7: P less than 0.01; alpha-mannosidase: 0.85 +/- 0.5; controls 0.39 +/- 0.3: P less than 0.05). Subcellular fractionation on reorientating sucrose density gradients showed a high-density peak of alkaline phosphatase suggestive of a specific increase in the biliary canalicular component of enzyme activity. Neutral alpha-glucosidase was shifted to denser fractions, indicative of an increase in the proportion of rough-to-smooth endoplasmic reticulum and consistent with enhanced synthesis of membranous enzymes. There was also evidence for increased fragility of intracellular organelles, particularly lysosomes. In contrast, histology showed either no abnormalities or minor degenerative changes compatible with hepatic underperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of castration and anatomical site on the plasma membrane structure and the activities of adenylate cyclase and 5'-nucleotidase in pig adipocytes

The effects of castration on fat cell plasma membrane structure and enzyme activities (adenylate cyclase and 5'-nucleotidase) were studied in pig adipose tissues in two fat deposits (subcutaneous and perirenal). Castration induced a fat cell enlargement in both tissues. Membrane cholesterol content was reduced and fluidity was increased in perirenal fat from castrated animals. Castration had no effect on 5'-nucleotidase activity which was higher in subcutaneous than in perirenal in both kinds of animals. Adenylate cyclase activity was studied in the presence of different effectors: isoproterenol-stimulations of the enzyme were not affected by castration but were site-specific. GppNHp-stimulated activities were increased in subcutaneous fat from castrated animals. Castration had no influence on forskolin stimulations. The magnitude of GppNHp- and forskolin-stimulated activities were found to be tissue-dependent. Membrane results are discussed in relation with castration-induced fat cell enlargement.

Ecto 5' nucleotidase (5'NT) as a sensitive indicator of human zinc deficiency

Ecto 5' nucleotidase (5'NT) is an integral plasma membrane enzyme located on most mammalian cells, and it is zinc dependent. We assayed 5'NT activity in the lymphocytes of two groups of subjects. The first group of six subjects had a mild state of zinc deficiency, as measured on the basis of zinc levels in lymphocytes, granulocytes, and platelets, but were otherwise healthy. They received 50 mg zinc as acetate orally for 12 weeks. The second six subjects were normal human volunteers in whom a mild state of zinc deficiency was induced experimentally by dietary techniques (4.2 to 5.6 mg daily zinc intake). For the assay of 5'NT, intact lymphocytes were incubated with 8-14C-labeled inosine monophosphate as substrate. Product and substrate were separated by thin-layer chromatography. Zinc level in cells was measured by flameless atomic absorption technique. In the first group of subjects with zinc deficiency, the decreased activity of 5'NT was corrected and the cellular zinc levels were normalized by oral zinc supplementation (p less than 0.01). In the second group of subjects, the baseline data were compared with those in early zinc depletion (4 to 8 weeks) and late depletion periods (greater than 20 weeks). A decrease in the activity of 5'NT was observed during the early zinc depletion phase. Zinc levels in lymphocytes, granulocytes, and platelets decreased significantly only during the late zinc depletion phase (p less than 0.01). Plasma zinc level did not change even during the late zinc depletion phase. Our studies show that 5'NT activity may be a sensitive and useful indicator of mild deficiency of zinc in human subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline phosphatase, 5'-nucleotidase and magnesium-dependent adenosine triphosphatase activities in the transitional epithelium of the rat urinary bladder

The cerium-based method was used to demonstrate cytochemically the ultrastructural localization of alkaline phosphatase (ALPase), 5'-nucleotidase (5'-Nase) and magnesium-dependent adenosine triphosphatase (Mg-ATPase) on the transitional epithelium of the rat urinary bladder. The reaction product for ALPase was found on the plasma membrane of all epithelial cells, except the luminal surface of superficial cells. The activity of 5'-Nase appeared on the plasma membrane of all bladder transitional epithelial cells, including the free surface of superficial cells. The Mg-ATPase reaction product was seen on the plasma membrane of superficial, intermediate and basal cells, but never on the luminal surface of superficial cells and it was only occasionally seen on the basal surface. The possible functions of these phosphatases have been discussed, and it was emphasized that the 5'-Nase activity present on the luminal surface of superficial cells may play a special role in the membrane movement of these cells in the transitional epithelium.

Cytochemical localization of enzyme markers in Tritrichomonas foetus

Cytochemical techniques associated with transmission electron microscopy were used for the localization in Tritrichomonas foetus of enzymes used as markers of different cell structures. Reaction product indicating the presence of Mg(2+)-adenosine triphosphatase (Mg(2+)-ATPase) and 5'-nucleotidase was observed in the plasma membrane. Glucose-6-phosphatase was seen in association with the endoplasmic reticulum, revealing its organization as parallel cisternae. Thiamino-pyrophosphatase was located in the cis-most region of the Golgi complex. Acid phosphatase was found within lysosomes as well as in several cisternae of the Golgi complex, in contrast to previous observations in mammalian cells. These observations provide support for the use of enzyme markers in future studies on cell fractionation of T. foetus.

Human follicular dendritic cells: isolation and characteristics in situ and in suspension

Follicular dendritic cells (FDC) in human tonsils, either in situ in follicular germinal centres or isolated from tissue, were characterized by immunohistochemical, enzyme cytochemical and electron microscopical methods. Using polyclonal and monoclonal antibodies, expression of DRC-1, Ki-M4, HLA-DR, CR1, C1q antigens, a macrophage marker, and surface IgG and IgM were found on isolated FDC and on FDC in situ. None of these reagents proved to be specific for FDC, e.g. the FDC-directed antibodies DRC-1 and Ki-M4 labelled B lymphocytes in cytofluorography. Enzyme cytochemical staining revealed activities of non-specific esterase, acid alpha-naphthylacetate esterase and ATPase in germinal centres and in freshly isolated FDC. Immunohistochemistry demonstrated a weak expression of CD4 by a fraction of isolated FDC, which was confirmed by two-colour immuno-staining and immuno-electron microscopy.

[Histochemistry of nucleoside phosphatases and phosphoglucomutase in the small intestine during coccidiosis in piglets]

The first day after birth, 22 conventional piglets were experimentally infected with the oocysts of the coccidia of I. suis (infection dose 200,000 oocysts). The activity of 5-nucleotidase (5-ribonucleotide phosphohydrolase, EC.3.1.3.5) and phosphoglucomutase (alpha-D-glucoso-1-phosphate phosphotransferase, EC.5.4.2.2) was densitometrically assessed in the mucosa of the small intestines of these piglets. Enzyme activities were studied in the infected piglets during the 2nd to 10th day after infection. The same histochemical examination was simultaneously performed in the intestinal mucosa of five control conventional piglets at an age of 2-14 days. 5-nucleotidase and phosphoglucomutase were found to have a high density in the mucosa of the small intestine of the control piglets: the high-density locations of these enzymes include, first of all, the supranuclear area of the absorption cells, the microvillous zone of enterocytes and the smooth muscle elements of lamina muscularis mucosae. The experimentally infected piglets showed a marked decline of the density of both enzymes during the infection. The deficit affected, for a transient period, the microvillous zone and the supranuclear region of enterocytes; the musculature of the mucous layer was affected permanently. The inactivity was more protracted in the case phosphoglutamase (especially 5 to 9 days after infection). The density of 5-nucleotidase showed a partial return to the normal already the 7th day after infection, with an interruption of resumption of activity on the 10th day. Resumption of enzyme activity in the lamina muscularis mucosae was not recorded during the infection. In the three locations under study, the density of none of the enzymes did reach parameters comparable with the controls at the end of the trial (10 days after infection).

Differences in lipid characteristics of undifferentiated and enterocytic-differentiated HT29 human colonic cells

In this paper we compared several lipid characteristics of the homogenate and the corresponding plasma membrane in undifferentiated and differentiated HT29 human colon cancer cells, using normal human colonic cells as a reference. Electron microscopy showed that HT29 cells were morphologically undifferentiated when cultured in the presence of either glucose or inosine without glucose at early confluency. On the contrary, HT29 cells cultured at late confluency in a glucose-free medium containing inosine or grown in nude mice exhibited an enterocytic differentiation with the presence of tight junctions and an apical brush border. The cell homogenate and the plasma membrane were prepared from each cell type. The study of specific marker enzymes showed the same degree of purity in all plasma membranes, with a highly marked increase of brush border-associated hydrolases (N-aminopeptidase and alkaline phosphatase) only in the organelles isolated from differentiated HT29 and colonic cells. Respective similar increases in the amount of free cholesterol and phospholipid and in the free cholesterol:phospholipid molar ratio were found in the plasma membrane as compared with the homogenate in all HT29 cell types. This ratio, due to an increased phospholipid content in both homogenate and plasma membrane, was lowered in colonic cells. No differences in the phospholipid profile were found between the homogenates of all cell types and the plasma membrane of undifferentiated HT29 cells, with the exception of a decrease of cardiolipin in this organelle. On the contrary, the plasma membrane phospholipid composition was different from that of the corresponding homogenate in differentiated HT29 and colonic cells. The most striking changes were a highly increased sphingomyelin amount and concomitant decreases in phosphatidylethanolamine, phosphatidylserine, and cardiolipin. Moreover, differences in the percentage of phosphatidylcholine plus sphingomyelin as well as in phosphatidylcholine:sphingomyelin, phosphatidylethanolamine, and/or phosphatidylcholine molar ratios were also found. The monounsaturated:polyunsaturated fatty acid ratio in phosphatidylethanolamine was similar in differentiated HT29 and colonic cells and lower than in undifferentiated HT29 cells. A decrease in this latter ratio in phosphatidylcholine was also observed in colonic cells and HT29 cells grown in nude mice. These changes were essentially due to opposite variations in the percentage of palmitoleic acid and those of linoleic and/or arachidonic acids in both phospholipids. Thus, these data indicate that undifferentiated HT29 cells were characterized by the absence of a specific phospholipid composition in their plasma membrane, which is suggested to be related to altered phospholipid sorting. The plasma membrane phospholipid profile reversed essentially to the normal pattern when HT29 cells recovered the ability to differentiate.

Enzymes of pyrimidine metabolism in the musculus complexus of the chick during development

The pattern of cytidylate and uridylate phosphatase, uridine phosphorylase, cytidine and cytosine deaminase activities has been studied in M. complexus during chick development. The comparison of these enzyme activities with thigh muscles ones has shown that quantitative and temporal changes occur, in parallel with the unusual pre-natal and early post-natal development of M. complexus. The results suggest that during the first period of incubation, UMP might follow the anabolic pathway UMP-UTP, which leads to cytidine nucleotides, while approaching the hatching, the catabolic pathway should prevail. In addition, immediately after hatching, pyrimidine metabolism is especially supported by cytidine nucleotides.

Effect of culture duration on hepatocyte subcellular membranes involved in endocytosis

The influence of culture duration on some characteristics of hepatocyte subcellular membranes involved in endocytosis was investigated. Activity of enzymes located in plasma membrane, Golgi apparatus and lysosomes increases with time. These modifications are accompanied with several changes in the sedimentation properties of these organelles. Endocytosis of [14C]sucrose and [14C]sucrose-LDL is not affected by culture age. On the contrary, [14C]sucrose-ASF endocytosis strongly decreases in these conditions. These modifications are delayed to some extent by lowering the temperature. Addition to the culture medium of 3-methyladenine (an inhibitor of autophagy), sodium butyrate, dimethylsulfoxide, phenobarbital or nicotinamide does not prevent the decrease of ASF endocytosis caused by culture duration. These results indicate that one must be cautious when extrapolating to liver in vivo, observations on endocytosis obtained with primary culture of hepatocytes.