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:1.11.1.7 (peroxidase)
65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The electrochemical single-cell analysis for enzyme activity was developed using microcells on a microcell array coupled with a positionable dual microelectrode. The microcell array with the nanoliter-scale microcells was constructed using simple chemical etching without photolithographic techniques. The positionable dual microelectrodes consisted of the nanometer-to-micrometer-radius Au disk working electrode and a approximately 80-microm-radius Ag/AgCl reference electrode. Peroxidase was chosen as the model enzyme. Factors that concern electrochemical single-cell analysis in microcells such as solution evaporation, interference of soluble oxygen, electrode size, solution volume, and electrode fouling were investigated and discussed. The 20 or 100 nL of detection volume was found to be suitable for peroxidase determination in single neutrophils or single acute promyelocytic leukemia cells without interference from intracellular macromolecules and electrode fouling, when the dual electrode with a 10-microm-radius Au disk working electrode was used. Cells were perforated with digitonin before transferring them into the microcells, to lyse cells easily. The perforated cells were transferred into the microcells by pushing a microscope slide on a drop of the cell suspension on the microcell array. After a single cell in the microcell was lysed using a freeze-thawing technique and allowed to dry, physiological buffer saline containing 2.0 x 10(-3) mol/L hydroquinone and 2.0 x 10(-3) mol/L H2O2 as the substrates of the enzyme-catalyzed reaction was added. The microcell array was positioned in a constant-humidity chamber to prevent evaporation. Then the dual electrode was inserted into the microcell by means of a scanning electrochemical microscope and the product benzoquinone of the enzyme-catalyzed reaction was voltammetrically detected. Peroxidase activity could be quantified using the steady-state current on the voltammogram after subtracting the blank and using the calibration curve.
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PMID:Measurement of enzyme activity in single cells by voltammetry using a microcell with a positionable dual electrode. 1638 32

We report a case of a patient aged about 53 years, who initially presented with hematological disorders (WBC: 44000/mm3, Hb: 11g/dl, Pit: 127000/mm3) without tumoral syndrome. The Wright-Giemsa stained bone marrow and peripheral blood smears showed a population of blast cells characterized by cells with high N/C and strongly basophilic cytoplasm without granules. The nuclei were predominantly round. Nuclear chromatin was fine and contained small nucleoli. Cytochemisty was positive for peroxidase activity. Immunophenotyping showed myeloid typical markers of granulocytic lineage (MP0+, CD13+, CD33+, CD117+, CD34-). The karyotype revealed the expression of t(15;17) chromosomal translocation. The diagnosis of acute myeloid leukaemia (AML) was then evoked initially. The cytological features corresponded closely to the M1 subtype as defined in the FAB classification. The patient was treated with induction therapy according to the 7/3 protocol. One month later, he was discharged from hospital on hematological and cytogenetic remission. He died at home because of a heart attack. From the biological findings the patient was retrospectively diagnosed as having promyelocytic leukemia (hyperbasophilic form).
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PMID:Identification of the translocation t(15;17) in acute myeloid leukemia (AML) initially classified as FAB M1: case report and review of the literature. 1658 58

Most patients with acute promyelocytic leukemia (APL) express PML-RAR alpha, the fusion product of t(15;17)(q22;q11.2). Transgenic mice expressing PML-RAR alpha develop APL with long latency, low penetrance, and acquired cytogenetic abnormalities. Based on observations that 4% to 10% of APL patients harbor oncogenic ras mutations, we coexpressed oncogenic K-ras from its endogenous promoter with PML-RAR alpha to generate a short-latency, highly penetrant mouse model of APL. The APL disease was characterized by splenomegaly, leukocytosis, extramedullary hematopoiesis (EMH) in spleen and liver with an increased proportion of immature myeloperoxidase-expressing myeloid forms; transplantability to secondary recipients; and lack of cytogenetic abnormalities. Bone marrow cells showed enhanced self-renewal in vitro. This model establishes a role for oncogenic ras in leukemia pathogenesis and thus validates the oncogenic RAS signaling pathway as a potential target for therapeutic inhibition in leukemia patients. This mouse model should be useful for investigating signaling pathways that promote self-renewal in APL and for testing the in vivo efficacy of RAS signaling pathway inhibitors in conjunction with other targeted therapies such as ATRA (all trans retinoic acid) and arsenic trioxide.
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PMID:Oncogenic K-ras cooperates with PML-RAR alpha to induce an acute promyelocytic leukemia-like disease. 1667 6

The aim of this study was to evaluate the value of CD117/CD11b phenotypic analysis to diagnosis and prognosis of acute promyelocytic leukemia (APL). Three- or four-color flow cytometry with a series of 22 monoclonal antibodies and CD45/Side Scatter (SSC) gating strategy were used to identify immunophenotypic characteristics of APL as compared to CML in chronic phase (CML-CP). PML/RAR alpha fusion gene was detected by using reverse-transcription polymerase chain reaction (RT-PCR) technique. The results showed that MPO, CD13 and CD33 were almost expressed in all patients with APL and CML-CP whereas HLA-DR and CD34, the hematopoietic progenitor cell markers, were rarely expressed. The positive rate of CD15 in APL was significantly lower than those in CML-CP (P < 0.01). CD117 was positive in 78.3% of the APL cases and in none of the cases of CML-CP. On the other hand, CD11b was almost positive in all cases of CML-CP, but only 16.9% of the APL cases were found positive for this antigen. The CD117+ CD11b- phenotype was present in 72.3% of APL cases while none of cases with CML-CP with this phenotype. Almost all of the cases with CML-CP had the phenotype of CD117- CD11b+. CD117- CD11b+ phenotype was detected in all patients recovering from APL with CD117+ CD11b- phenotype at diagnosis and after treatment with all-trans-retinoic acid (ARTA) for 2 months. PML/RAR alpha fusion gene was positive in 80.6% (25/31) of the APL cases, of which, 64% of the cases belonged to the type L while only 36% of the cases were showed type S for this fusion gene. The positive rates of CD117 were 87.5%, 44.4% and 33.3% in type L group, S group and negative group respectively. It is concluded that analysis of both CD117 and CD11b phenotype may be helpful to the diagnosis, therapy and prognosis of APL in children and adults and to differentiation of APL from recovering benign myeloid proliferation.
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PMID:[Expressions of CD117 and CD11b in patients with APL at diagnosis and post-treatment]. 1692 91

A 30 years-old man was administrated with dizziness and fatigue for half month, and the big toe on his left foot got the prolonged bleeding of wound complicated with fever 7 days before the admission. The physical examination (PE) discovered that the case suffered from the anemic appearance, lower part tenderness of sternum, petechiae and purpura on skin of lower extremities, and with remaining not to be remarkable. The examination of blood routine showed WBC 2.3 x 10(9)/L, Hb 60/L, BPC 34 x 10(9)/L and blasts 0. 85. The bone marrow smear indicated markedly the hypercellularity, promyelocytes 89% and strongly positive myeloperoxidase (MPO). The PT and APTT were prolonged, and the FDP and D-dimer were positive. The acute promyelocytic leukemia (APL) with DIC was diagnosed. The patient was administered with all-trans retinoic acid (ATRA) with dosage of 20 mg three times per day. After 14 week treatment, the patient did not get complete remission. Then the tanshinone II A was taken orally with 30mg twice each day. After 8 week treatment of tanshinone II A, the blood routine was restored to normal. Four weeks later, the bone marrow also became normally, and the patient got a complete remission (CR). After more than 3 months of consolidation therapy with tanshinone II A, the patient was relapsed. When the homoharringtonine and cytarabine (HA) were given, the patient was got CR again. Three years later, he was relapsed secondarily, and then died of intracranial hemorrhage. The tanshinone II A could induce CR of APL with ATRA resistance, no side effect was observed; there is a reoccurring possibility from consolidation therapy with tanshinone II A.
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PMID:[Complete remission of acute promyelocytic leukemia resisting all-trans retinoic acid of one case treated by tanshinone II A]. 1723 2

Cytochemistry and immunophenotyping are established methods in the diagnosis of most leukemias but the role of electron microscopy in diagnosis, apart from understanding the cellular morphology is less studied. We present here 50 cases of acute leukemias that were studied for morphology, conventional cytochemistry, immunophenotyping and transmission electron microscopy (TEM), including ultrastructural cytochemistry using myeloperoxidase (MPO) and platelet peroxidase activity. TEM morphology using ultrastructural cytochemistry helped in definitive typing in one mixed lineage leukemia case, one AML-M5b, one AML-M6b and one microgranular variant of APML. Thus, ultrastructural studies may be useful in accurate diagnosis of biphenotypic leukemia and further classification of acute leukemias. Also, in cases with hypercellular marrow and with associated myelofibrosis, where the marrow aspirate gives low cell count, ultrastructural studies are a valuable aid to arriving at an accurate diagnosis.
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PMID:Cytochemical, immunophenotypic and ultrastructural characterization of acute leukemias: a prospective study of fifty cases: haematological malignancy. 1732 54

Aminoglutethimide (AG) is a first-generation aromatase inhibitor used for estrogen-dependent breast cancer. Unfortunately, its use has also been associated with agranulocytosis. We have investigated the metabolism of AG by myeloperoxidase (MPO) and the formation of an MPO protein free radical. We hypothesized that AG oxidation by MPO/H2O2 would produce an AG cation radical that, in the absence of a biochemical reductant, would lead to the oxidation of MPO. We utilized a novel anti-DMPO antibody to detect DMPO (5,5-dimethyl-1-pyrroline N-oxide) covalently bound to protein, which forms only by the reaction of DMPO with a protein free radical. We found that AG metabolism by MPO/H2O2 induced the formation of DMPO-MPO, which was inhibited by MPO inhibitors and ascorbate. Glutethimide, a congener of AG that lacks the aromatic amine, did not cause DMPO-MPO formation, indicating the necessity of oxidation of the aniline moiety in AG. When analyzed by electron spin resonance spectroscopy, we detected a phenyl radical adduct, derived from AG, which may be involved in the free radical formation on MPO. Furthermore, we also found protein-DMPO adducts in MPO-containing, intact human promyelocytic leukemia cells (HL-60). MPO was affinity-purified from HL-60 cells treated with AG/H2O2 and was found to contain DMPO. These findings were also supported by the detection of protein free radicals with electron spin resonance in the cellular cytosolic lysate. The formation of an MPO protein free radical is believed to be mediated by one of two free radical drug metabolites of AG, one of which was characterized by spin trapping with 2-methyl-2-nitrosopropane. These results are the first demonstration of MPO free-radical detection by the anti-DMPO antibody that results from drug oxidation. We propose that drug-dependent free radical formation on MPO may play a role in the origin of agranulocytosis.
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PMID:Aminoglutethimide-induced protein free radical formation on myeloperoxidase: a potential mechanism of agranulocytosis. 1760 75

Identification of cytosolic proteins differentially expressed between types of leukemia and lymphoma may provide a molecular basis for classification and understanding their cellular properties. Two-dimensional fluorescence difference gel electrophoresis (DIGE) and mass spectrometry have been used to identify proteins that are differentially expressed in cytosolic extracts from four human leukemia and lymphoma cell lines: HL-60 (acute promyelocytic leukemia), MEC1 (B-cell chronic lymphocytic leukemia), CCRF-CEM (T-cell acute lymphoblastic leukemia) and Raji (B-cell Burkitt's lymphoma). A total of 247 differentially expressed proteins were identified between the four cell lines. Analysis of the data by principal component analysis identified 22 protein spots (17 different protein species) differentially expressed at more than a 95% variance level between these cell lines. Several of these proteins were differentially expressed in only one cell line: HL-60 (myeloperoxidase, phosphoprotein 32 family member A, ras related protein Rab-11B, protein disulfide-isomerase, ran-specific GTPase-activating protein, nucleophosmin and S-100 calcium binding protein A4), and Raji (ezrin). Several of these proteins were differentially expressed in two cell lines: Raji and MEC1 (C-1-tetrahydrofolate synthase, elongation factor 2, alpha- and beta-tubulin, transgelin-2 and stathmin). MEC1 and CCRF-CEM (gamma-enolase), HL-60 and CCRF-CEM (ubiquitin-conjugating enzyme E2 N). The differentially expressed proteins identified in these four cell lines correlate with cellular properties and provide insights into the molecular basis of these malignancies.
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PMID:Differentially expressed cytosolic proteins in human leukemia and lymphoma cell lines correlate with lineages and functions. 1769 27

Combretastatins are stilbene-based, tubulin depolymerization agents with selective activity against the tumor vasculature; two variants (A-1 and A-4) are currently undergoing clinical trials. Combretastatin A-1 (CA1) has a greater antitumor effect than combretastatin A-4 (CA4). We hypothesized that this reflects the enhanced reactivity conferred by the second (ortho) phenolic moiety in CA1. Oxidation of CA1 by peroxidase, tyrosinase, or Fe(III) generates a species with mass characteristics of the corresponding ortho-quinone Q1. After administration of CA1-bis(phosphate) to mice, the hydroquinone-thioether conjugate Q1H2-SG, formed from the nucleophilic addition of GSH to Q1, was detected in liver. In competition, electrocyclic ring closure of Q1, over a few minutes at pH 7.4, leads to a second ortho-quinone product Q2, characterized by exact mass and NMR. This product was also generated by human promyelocytic leukemia (HL-60) cells in vitro, provided that superoxide dismutase was added. Q2 is highly reactive toward glutathione (GSH) and ascorbate, stimulating oxygen consumption in a catalytic manner. Free radical intermediates formed during autoxidation of CA1 were characterized by EPR, and the effects of GSH and ascorbate on the signals were studied. Pulse radiolysis was used to initiate selective one-electron oxidation or reduction and provided further evidence, from the differing absorption spectra of the radicals formed on oxidation of CA1 or reduction of Q2, that two different quinones were formed on oxidation of CA1. The results demonstrate fundamental differences between the pharmacological properties of CA1 and CA4 that provide two possible explanations for their differential activities in vivo: oxidative activation to a quinone intermediate likely to bind to protein thiols and possibly to nucleic acids and stimulation of oxidative stress by enhancing superoxide/hydrogen peroxide production. The observation of the GSH conjugate Q1H2-SG in vivo provides a new marker for oxidative metabolism of relevance to current clinical trials of CA1-bis(phosphate) (OXi4503).
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PMID:Oxidative metabolism of combretastatin A-1 produces quinone intermediates with the potential to bind to nucleophiles and to enhance oxidative stress via free radicals. 1794 99

Procainamide (PA) is a drug that is used to treat tachycardia in postoperative patients or for long-term maintenance of cardiac arrythmias. Unfortunately, its use has also been associated with agranulocytosis. Here, we have investigated the metabolism of PA by myeloperoxidase (MPO) and the formation of an MPO protein free radical. We hypothesized that PA oxidation by MPO/H 2O 2 would produce a PA cation radical that, in the absence of a biochemical reductant, would lead to the free radical oxidation of MPO. We utilized a novel anti-DMPO antibody to detect DMPO (5,5-dimethyl-1-pyrroline N-oxide) covalently bound to protein, which forms by the reaction of DMPO with a protein free radical. We found that PA metabolism by MPO/H 2O 2 induced the formation of DMPO-MPO, which was inhibited by MPO inhibitors and ascorbate. N-acetyl-PA did not cause DMPO-MPO formation, indicating that the unsubstituted aromatic amine was more oxidizable. PA had a lower calculated ionization potential than N-acetyl-PA. The DMPO adducts of MPO metabolism, as analyzed by electron spin resonance spectroscopy, included a nitrogen-centered radical and a phenyl radical derived from PA, either of which may be involved in the free radical formation on MPO. Furthermore, we also found protein-DMPO adducts in MPO-containing, intact human promyelocytic leukemia cells (HL-60). MPO was affinity-purified from HL-60 cells treated with PA/H 2O 2 and was found to contain DMPO using the anti-DMPO antibody. Mass spectrometry analysis confirmed the identity of the protein as human MPO. These findings were also supported by the detection of protein free radicals with electron spin resonance in the cellular cytosolic lysate. The formation of an MPO protein free radical is believed to be mediated by free radical metabolites of PA, which we characterized by spin trapping. We propose that drug-induced free radical formation on MPO may play a role in the origin of agranulocytosis.
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PMID:Procainamide, but not N-acetylprocainamide, induces protein free radical formation on myeloperoxidase: a potential mechanism of agranulocytosis. 1848 81


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