Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimental infection of hamsters with Leishmania donovani caused visceral leishmaniasis in which hematological changes occurred. The infected hamsters were anemic and reticulocyte counts were high. No significant change in the serum erythropoietin level was noted. Red cell membrane Na(+)-K(+)-ATPase and acetylcholinesterase activities increased. Osmotic fragility of the erythrocytes from infected animals increased. The level of 2,3-diphosphoglycerate of the red cells increased with the degree of anemia.
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PMID:Anemia in experimental visceral leishmaniasis in hamsters. 131 Jul 31

In this study, specific binding sites were examined for erythropoietin (EPO) on the mouse leukemic cell line, L8057. This cell line is megakaryoblastic in origin as evidenced by an enlargement of cell size, multinuclearity, intense activity of acetylcholinesterase, more expression of glycoprotein IIb and IIIa antigen, and higher ploidy distribution after the treatment with 12-o-tetradecanoylphorbor-13-acetate (TPA). The original undifferentiated cells possessed a single class of low affinity binding sites for recombinant human (rh) EPO with a Kd of 3.5 nM. Following the treatment with TPA, high affinity binding sites (Kd; 440 pM) were expressed in addition to the low affinity sites. EPO stimulated the incorporation of 3H-leucine into TPA-treated L8057 cells, and the maximal effect of EPO was observed at the same order as the Kd value of high affinity sites. The present data demonstrates that the expression of high affinity binding sites for EPO is associated with the differentiation of L8057 cells which have megakaryocytic characteristics. Furthermore, protein synthesis stimulated by EPO may be mediated through the high affinity sites.
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PMID:Expression of high affinity binding sites for erythropoietin on L8057 cells, a mouse megakaryoblastic cell line, associated with cell differentiation. 131 Nov 45

Recombinant human erythropoietin (rHuEpo) was tested for its ability to stimulate rat megakaryopoiesis in vivo. Groups of Sprague-Dawley rats were injected with rHuEpo at a daily dose of 20, 80, or 200 U for 5 days. Significant thrombocytosis (a 30 to 40% increase over the control level) was found only in the rats that received 200 U/day, but some changes in the megakaryopoietic parameters were observed not only in the rats given 200 U/day, but also in those receiving 80 or 20 U/day. rHuEpo induced a dose-dependent elevation of megakaryocyte ploidy, with the maximum 45% increase in the mean ploidy over the control level seen in rats given 200 U/day. The size of the marrow megakaryocytes also increased dose-dependently. rHuEpo did not increase bone marrow megakaryocyte numbers, but it increased those in the spleen in a dose-dependent manner. A change of these parameters was seen as early as day 1 at 24 h after initiating the Epo injections at a time when significant thrombocytosis was already present. Moreover, a significant increase in the ratio of small acetylcholinesterase-positive bone marrow cells was also found, with the greatest response noted on day 1. Administration of a large dose of iron did not alter the thrombopoietic effect of rHuEpo. These results suggest that the in vivo administration of rHuEpo stimulates the maturation of mature as well as immature megakaryocytes already present in the bone marrow.
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PMID:Effects of short-term administration of recombinant human erythropoietin on rat megakaryopoiesis. 155 21

We have devised a simultaneous assay system for megakaryocyte colony-stimulating factor (Meg-CSF) and megakaryocyte potentiator (Meg-Pot) by modifying a quantitative measuring technique for acetylcholinesterase activity (Ach-E) of megakaryocytes by automatic colorimetry using microplates. We cultured murine bone marrow cells treated with diisopropyl fluorophosphate in a serum-free system with serum-free pokeweek mitogen-stimulated spleen cell conditioned medium (PWM-SCM) and an unknown factor, preparing two microplates with the identical culture system. In the first plate, the total number of Ach-E-positive cells induced solely by the factor tested was indicative of Meg-CSF activity and additive increases in this parameter on simultaneous addition of PWM-SCM and the factor tested were indicative of early Meg-Pot activity. Total Ach-E activity (total change at optical density of 414 nm) per well was measured in the second plate to calculate total change at optical density of 414 nm per megakaryocyte, an indicator of late Meg-Pot activity. With this system, recombinant human erythropoietin showed both Meg-CSF and early and late Meg-Pot activities in in vitro megakaryopoiesis. Recombinant murine granulocyte-macrophage colony-stimulating factor possessed weak Meg-CSF and early Meg-Pot activity, whereas recombinant human granulocyte colony-stimulating factor exhibited late Meg-Pot activity and thrombocytopenic serum exhibited early and late Meg-Pot activities. This assay system is useful in screening Meg-CSF or Meg-Pot activities in unknown factors.
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PMID:Simultaneous assay for megakaryocyte colony-stimulating factor and megakaryocyte potentiator and its application. 169 13

Partially purified thrombopoietic factor (TPF) potentiated in vitro murine megakaryopoiesis induced by recombinant human erythropoietin (rh-Epo). High doses (2.5-10 units) of rh-Epo generated a considerable number of megakaryocytes in a dose-dependent manner in a serum-free liquid culture, whereas low doses of rh-Epo (0.5-1 units) failed to generate megakaryocytes. The addition of high doses of rh-Epo and TPF caused a significant increase of megakaryocytes in comparison with high doses of rh-Epo alone. Furthermore, low doses of rh-Epo with TPF caused generation of a small number of megakaryocytes, although TPF alone did not generate megakaryocytes. In addition, TPF enhanced the acetylcholinesterase (Ach-E) activity of megakaryocytes induced by rh-Epo. The potentiating effects of both factors, rh-Epo and thrombopoietic factor, may play an important role in thrombocytopenic states in vivo as well as in in vitro megakaryopoiesis.
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PMID:Thrombopoietic factor enhances murine megakaryopoiesis induced by recombinant erythropoietin. 174 49

The availability of a preparation of recombinant human erythropoietin (rEp) prompted us to investigate the role of Ep in the regulation of megakaryocytopoiesis in mice, using experimental procedures by which the effects on the mitotic and post-mitotic compartment of megakaryocytes could be evaluated separately. In agar cultures of murine bone marrow cells, either serum-depleted or serum-supplemented, rEp (0.1-2 U/ml) did not stimulate megakaryocyte colony formation and when it was added to suboptimal amount of spleen cell-conditioned medium (SCM), it failed to show a significant synergistic activity. On the contrary, rEp increased the number of megakaryocytic colonies developed from splenic precursors in the presence of suboptimal amounts of SCM, although it was unable per se to stimulate colony formation. The effects of rEps on megakaryocyte maturation and platelet production were studied in vivo evaluating the incorporation of 75Se-selenomethionine into platelets, the platelet count and platelet size, and the number of megakaryocyte precursors (small acetylcholinesterase positive cells, sAchE) in the bone marrow of mice injected with 1-8 U of rEp. No modification of these parameters was found in comparison with control mice. On the other hand, rEp increased the number of recognizable splenic megakaryocytes in a dose-dependent fashion. These data suggest that rEp has little influence on megakaryocytopoiesis, at least at the doses we used and which are known to elicit a maximal response of erythropoiesis. However, a subset of megakaryocytes with particular kinetic properties, such as those in the spleen of mice, may be responsive to relatively high doses of rEp. The significance of this observation in the overall regulation of megakaryocytopoiesis remains to be determined.
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PMID:Recombinant human erythropoietin has little influence on megakaryocytopoiesis in mice. 271 70

To determine if erythropoietin influences megakaryocytopoiesis, the purified recombinant human hormone (rEpo) was added to serum-free liquid cultures of murine marrow. A dose-related increment in acetylcholinesterase (AchE) production was observed. To assess if increments in this relatively megakaryocyte-specific enzyme marker were mediated by a direct hormone-megakaryocyte interaction rather than via an accessory cell population, rEpo was added to cultures of isolated single megakaryocytes. A significant, dose-related increase in cell size was noted in the presence of the hormone, accompanied by a high probability of an increase in cellular DNA content. The data show that rEpo does directly influence some aspects of megakaryocytic maturation, although the physiologic significance of this effect remains unknown.
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PMID:Erythropoietin and megakaryocytopoiesis. 293 Aug 46

We studied the effects of recombinant erythropoietin (r-Epo) and thrombocytopenic serum (TS) on the cytoplasmic maturation of megakaryocytes derived from colony-forming units megakaryocyte (CFU-M). Serotonin content, ATP content, acetylcholinesterase (Ach-E) activity per megakaryocyte, and electron microscopic analysis were selected as markers of cytoplasmic maturation. Megakaryocytes induced by pokeweed mitogen-stimulated spleen cell-conditioned medium (PWM-SCM) alone showed low levels of ATP content and Ach-E activity, which did not increase during culture, as well as a low level of serotonin content, which gradually accumulated during day 7 of culture. When r-EPo was added to the culture system on day 3 after megakaryocytic colony formation with PWM-SCM, the serotonin content in megakaryocytes increased markedly but ATP content and Ach-E activity did not increase significantly. In contrast, TS caused an increase in ATP content and Ach-E activity, but did not cause an increase in serotonin content. Electron microscopic analysis showed that the demarcation membrane system (DMS) developed defectively only in local areas with the addition of r-Epo and PWM-SCM, whereas the DMS developed normally and dense granules were generated to near normal with the addition of TS. Recombinant Epo may act on the early stage of cytoplasmic maturation, whereas TS may act on the late stage of cytoplasmic maturation. The results shown herein suggest that at least two different factors may be necessary for full in vitro cytoplasmic maturation of megakaryocytes derived from CFU-M.
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PMID:In vitro regulatory mechanisms for cytoplasmic maturation of murine megakaryocytes derived from colony-forming units megakaryocyte (CFU-M). 340 56

The contention that erythropoietin (Epo) affects platelet production was investigated in the rat with recombinant human Epo (rHuEpo). In normal rats, Epo caused a dose-dependent increase in both reticulocyte and platelet numbers, the reticulocyte response preceding that of platelets. Withdrawal of Epo resulted in reticulocytes and platelets returning to control levels. [75Se]-selenomethionine incorporation into platelets was also enhanced in response to Epo. Chronic daily administration of rHuEpo resulted in steady state erythrocyte levels after 12 to 14 days, which were elevated 20% above controls. Attainment of this steady state was associated with both reticulocytes and platelets returning to control levels despite continued administration of Epo, an effect not associated with a change in the half-life of circulating Epo. In polycythemic rats a platelet response was observed before an effect on reticulocytes. Erythropoietin caused a 2.4-fold increase in the frequency of small acetylcholinesterase-positive cells within 24 hours, and increased the mean megakaryocyte diameter within 48 hours. Furthermore, the [3H]-thymidine labeling index of megakaryocytes from rats treated for 24 hours with rHuEpo was increased for all stages of megakaryocyte maturation. These results support the proposal of an effect of Epo on rat megakaryocytes causing increased platelet production.
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PMID:Effects of recombinant human erythropoietin on megakaryocytes and on platelet production in the rat. 341 80

To determine if erythropoietin affects megakaryocytopoiesis, we measured acetylcholinesterase (AchE) activity, a marker of the murine megakaryocytic lineage, after the addition of human recombinant erythropoietin to serumless murine bone marrow cultures. Erythropoietin increased AchE activity substantially. Moreover, when the hormone was added to serumless cultures of 426 isolated single megakaryocytes derived from megakaryocytic colonies, erythropoietin induced a significant increase in the diameters of these cells. From a Bayesian analysis of the likelihood that some megakaryocytes increased in DNA content during the culture period, we estimate that 61% of the cells increased in ploidy. These data indicate that the action of erythropoietin is not restricted to the erythroid lineage.
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PMID:Human recombinant erythropoietin promotes differentiation of murine megakaryocytes in vitro. 379 27


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