Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D02003 (NBT)
 1,323 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A polarographic method to assess the scavenging capacity of a molecule for O2-. is proposed. This method is based on the fact that O2-. is not detected by the Clark electrode and that a scavenger competes with spontaneous dismutation of O2-. So, the reduction of O2 into O2-. and the decomposition of H2O2 by catalase, releasing O2, show a biphasic kinetic. Various kinetic parameters can be used to calculate the nmol of O2-. scavenged and also supply data on the reaction mechanisms (oxidation or reduction of O2-.) involved in scavenging. This method presents several other advantages: scavenging capacity can be assayed without added indicators which themselves behave as scavengers (as demonstrated for NBT), the presence of scavengers which interfere with the O2-. generating system (xanthine-xanthine oxidase) does not invalidate the measurements made.
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PMID:Superoxide anion scavenging capacity measured by a polarographic method. Comparison with a colourimetric method. 133 24

Basophilic granulocytes were purified from the blood of normal individuals by successive isopyknic centrifugation and elutriation centrifugation. Starting with the leukocyte-rich fraction of 500 ml of blood, we recovered 31 to 80% (mean 51%, n = 20) of the basophils in 45 to 87% purity (mean 69%, n = 23). The contaminating cells were mainly lymphocytes. The basophils were greater than 98% vital (exclusion of ethidium bromide and hydrolysis of fluorescein diacetate). The histamine content of the basophils was 1.1 to 2 pg/cell (mean 1.6 pg/cell, n = 22). With anti-IgE, 30 to 50% of the histamine was released; with phorbol myristic acetate (PMA) or the calcium ionophore A23187, 70 to 100% of the histamine was released. Serum-opsonized zymosan (STZ) did not induce histamine release. Reactions with monoclonal antibodies revealed that the basophils expressed the C3bi receptor (CR3) and the leukocyte function-associated antigen 1 (LFA1), but not the gp 150,95 antigen, the C3b receptor (CR1), or the low avidity Fc gamma receptor. Basophils carry class I but not class II HLA antigens. During incubation of the basophils with serum-opsonized Staphylococcus aureus or Escherichia coli, these bacteria were neither phagocytized nor killed. STZ, PMA, A23187, or anti-IgE did not initiate an "oxidative burst" in the basophils. This was tested with oxygen consumption, cytochrome c reduction, NBT reduction, chemiluminescence, and release of hydrogen peroxide. Moreover, we did not detect cytochrome b558, superoxide dismutase, catalase, or peroxidase in the basophils. Of the typical granule-associated enzymes lysozyme, Vitamin B12-binding protein, and beta-glucuronidase, only beta-glucuronidase was present in the basophils in detectable amounts. This enzyme was released, together with histamine, on incubation of the cells with PMA, A23187, or anti-IgE, but not with STZ. We conclude that basophils from normal human blood are not phagocytes and are probably not involved in the oxidative defense of the host against foreign antigens.
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PMID:Metabolic comparison between basophils and other leukocytes from human blood. 300 19

The effect of EDTA and H2O2 on iron autoxidation in Mops buffer depends on the pH of the solution. At acidic pH, EDTA caused the oxidation of a stoichiometric amount of iron. At neutral and alkaline pH, EDTA and H2O2 not only oxidizes a stoichiometric amount of iron but also causes the oxidation of the Fe2+ exceeding the concentration of these compounds. In the presence of EDTA, oxidation of Fe2+ in exceeding the concentration of these compounds has a shorter lag phase and an increased rate compared with that in the absence. The solution develops a yellow colour whose intensity is proportional to the amount of Fe2+ exceeding the concentration of these compounds in solution. When the reaction is conducted in the presence of NBT, formazan formation is greatly reduced compared to the control without EDTA and H2O2. The Fe3+-EDTA complex and Fe3+ affected iron oxidation, development of the yellow colour and NBT reduction in a similar fashion. In all these experimental conditions, iron oxidation is greatly reduced in the presence of mannitol, sorbitol and catalase. In phosphate buffer, EDTA oxidized a stoichiometric amount of iron without affecting free Fe2+ oxidation. Fe3+ has no effect on iron oxidation in this buffer.
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PMID:Iron oxidation in Mops buffer. Effect of EDTA, hydrogen peroxide and FeCl3. 314 95

A six year old boy is described who suffured from recurrent and protracted infections of multiple organs by various catalase positive bacteria. A severe episode of osteomyelitis involving several bones was caused by Aspergillus fumigatus. Studies of his PMNs revealed impaired metabolic as well as microbicidal functions characteristic of CGD. Chemiluminescence in response to both opsonized zymosan and sodium fluoride was markedly depressed, while control PMNs showed significant responses. Control leukocytes suspended in patient's serum likewise evoked normal chemiluminescence. Microbicidal activity against staphylococcus aureus 502A was also decreased using patient's PMNs, whereas control PMNs were able to reduce the number of colony forming bacteria by 2 logs in 120 minutes. Viable intracellular bacteria after lysis of extracellular bacteria formed 3 X 10(7) colonies from patient's PMNs and less than 2 X 10(5) colonies from the control. NBT dye reduction studies of the family members suggested an x-linked recessive mode of inheritance. The extraordinary nature of this case lies in the discovery of an associated intrinsic cellular defect of chemotaxis involving his polymorphonuclear leukocytes. Specifically, the Rebuck skin window showed predominantly mononuclear cells from 4 up to 24 hours. In addition, the patient's PMNs failed to migrate in response to cultured filtrates of E. coli as the chemoattractant. This abnormality persisted in the presence of autologous plasma or serum as well as in control plasma or serum. Control PMNs showed normal chemotaxis in the presence of the patient's plasma or serum. The extent to which the rare coexistence of these two phenomena influence the clinical disease is not known and remains to be elucidated.
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PMID:Intrinsic polymorphonuclear chemotactic defect in a boy with chronic granulomatous disease. 667 Jun 61

The capacity of macrophages activated in vivo and in vitro to kill Plasmodium yoelii was investigated. Macrophages activated by BCG-, Con A-, or malaria-induced lymphokines (LK) were cultured with P. yoelii-parasitized erythrocytes (PE). In some experiments, effector and target cells were separated by a 0.45-micron filter. Parasite viability was assessed a) in vivo by injection of mice and quantitative detection of parasites by RIA or b) in vitro by the incorporation of 3H amino acids into parasite proteins. Activated macrophages killed target PE in a dose-dependent manner by elaborating a membrane-permeable soluble factor(s). The addition of small amounts of immune serum augmented the killing of the parasites. LK-activated macrophages underwent an oxidative burst upon the phagocytosis of PE as evidenced by the accumulation of reduced formazan in the NBT assay. The magnitude of the oxidative response corresponded to the number of parasites that were ingested. The phagocytosis-induced oxidative burst was necessary for subsequent killing of Plasmodium. Parasites incubated in microchambers separated from macrophages by a 0.45-micron filter were susceptible to H2O2 released by LK-activated macrophages incubated with PMA, opsonized zymosan, or P. yoelii antigen. Inhibition of protein synthesis by parasites exposed to products of activated macrophages was abrogated by preincubating macrophages with catalase but not with SOD, mannitol, or histidine. These results suggest that phagocytosis-associated oxidative mechanisms mediate the destruction of the malaria parasite. Hence, cell-mediated as well as antibody-dependent mechanisms cooperate in the immune response against malaria.
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PMID:Oxidative killing of the intraerythrocytic malaria parasite Plasmodium yoelii by activated macrophages. 669 Jun 6

The effect of H2O2 and catalase on isolated rat cerebellum nitric oxide (NO) synthase activity was determined by measuring the conversion of L-[3H]arginine to L-[3H]citrulline. H2O2 (1-5 mM) markedly increased NO synthase activity in the presence of endogenous catalase (72 +/- 4 U/mL). This effect of H2O2 was further increased by exogenous catalase (200 U/mL). Exogenous catalase (0.1 to 1000 U/mL) by itself had no significant effect on NO synthase activity. Nitroblue tetrazolium chloride, an electron acceptor, inhibited NO synthase activity in a concentration-dependent manner. This study suggests that H2O2 is not directly involved in NO synthesis and that the H2O2/catalase stimulation of NO synthase activity may be due to the excess oxygen produced by the H2O2/catalase system.
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PMID:Effect of hydrogen peroxide and catalase on rat cerebellum nitric oxide synthase. 751 55

Tumor cells usually contain lower superoxide dismutase (SOD) activity than differentiating cells, suggesting the involvement of oxygen free radicals in cell maturation. The effects of a system known to produce the OH. radicals were tested on HL-60 cells cultured under optimum conditions for 96 hr. Hydroxyl radicals were generated by a Fenton reaction, involving an ADP-Fe2+ (or ATP-Fe2+) complex and H2O2. Changes induced by OH. were compared to the effects of DMSO-induced differentiation of HL-60 cells. Cell numbers, viability, thymidine incorporation, TPA-induced NBT reduction and propidium iodide staining in flow cytometry were determined. The OH. generating system inhibited the growth and thymidine incorporation of leukemic cells in a manner dependent on the dose of added H2O2 (from 0.005 to 0.05 mM). In addition, an increasing proportion of the treated cells displayed signs of cell differentiation. In DMSO-treated cells, SOD and catalase activities increased after 6 days of culturing. The results show that a portion of the OH. free radicals derived from H2O2, produced by the action of SOD, may be a necessary prerequisite for differentiation, whereas an overproduction of OH. causes cell lethality or aging. We suggest that OH. free radicals may have a more complex role in cell physiology than simply causing oxidative damage.
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PMID:Induction of granulocytic maturation in HL-60 human leukemia cells by free radicals: a hypothesis of cell differentiation involving hydroxyl radicals. 822 30

108 guinea pigs were infected with M-tuberculosis 2 weeks later 36 of them were put on treatment with rifampicin and isoniazid, the rest served as untreated control. The comparison was made of mixed population of all the cells isolated from bronchoalveolar lavage versus pure fraction of alveolar macrophages (AM) by spontaneous and BCG killed culture-stimulated NBT-test, activity of superoxide dismutase and catalase, levels of malonic dialdehyde. Estimations were conducted 1 day, 1, 2 and 6 weeks after inoculation in untreated animals and after 1 months of treatment in treated animals. AM lost ability for stimulation to the end of 24 h period since inoculation. 1-2 weeks later metabolic depression and complete areactivity occurred. Mixed population within postinoculation week 1 mobilized its defense potential. In extensive generalized tuberculosis all the cells of the respiratory tract worked for self-defense and lost protecting abilities. Specific chemotherapy reestablished functional status of both AM and cell population on the whole.
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PMID:[Oxidative metabolism changes in respiratory tract cells of guinea pigs during natural development of experimental tuberculosis and under specific chemotherapy]. 865 93

In order to assess the immunological system of the chemical plant workers certain rates of cellular and humoral immunity were estimated. The study group was composed of 19 males employed in the production of liquid pesticides, and 18 females performing ancillary jobs and handling closed containers. They were alternatively exposed to phosphoroorganic compounds and pyrethroides, and to chlorinated hydrocarbons, carbamates, nitrophenols and organic solvents, however exposure to the latter was lower. Chronic bronchitis was observed in 7 (37%) males and 4 (22%) females. Serum concentrations of immunoglobulins G, A and M, complement protein Cs, and circulating immune complexes were estimated. The peripheral blood leukocyte count and percentage, the granulocyte adherence and phagocytic activity, spontaneous NBT-dye reduction as well as cytochemical reactions to alkaline and acid phosphatase, beta-glucuronidase, myeloperoxidase and catalase of neutrophils were evaluated; the lymphocyte subpopulations CD3, CD4, CD8, CD16 were also estimated. As compared to controls, a significantly increased serum IgG concentration was found, together with elevated IgM in males and IgA in females. The leukocyte count in males was significantly higher. A considerable decrease in the percentage of neutrophils was accompanied by a significantly greater spontaneous NBT-dye reduction in both groups. Neutrophil adherence impairment was observed in males. Cytochemical reactions to beta-glucuronidase and catalase in both sexes, to alkaline and acid phosphatase in females, and to myeloperoxidases in males were significantly lowered, whereas the reaction to acid phosphatase in males was significantly enhanced. The percentages of lymphocytes CD3, CD4 and the CD4/CD8 ratio were significantly decreased.
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PMID:Humoral and cellular immunity rates in chemical plant workers employed in the production of liquid pesticides. 880 24

Reactive oxygen species such as superoxides, hydrogen peroxide (H2O2) and hydroxyl radicals have been suggested to be involved in the catalytic action of nitric oxide synthase (NOS) to produce NO from L-arginine. An examination was conducted on the effects of oxygen radical scavengers and oxygen radical-generating systems on the activity of neuronal NOS and guanylate cyclase (GC) in rat brains and NOS from the activated murine macrophage cell line J774. Catalase and superoxide dismutase (SOD) showed no significant effects on NOS or GC activity. Nitroblue tetrazolium (NBT, known as a superoxide radical scavenger) and peroxidase (POD) inhibited NOS, but their inhibitory actions were removed by increasing the concentration of arginine or NADPH respectively, in the reaction mixture. NOS and NO-dependent GC were inactivated by ascorbate/FeSO4 (a metal-catalyzed oxidation system), 2'2'-azobis-amidinopropane (a peroxy radical producer), and xanthine/xanthine oxidase (a superoxide generating system). The effects of oxygen radicals or antioxidants on the two isoforms of NOS were almost similar. However, H2O2 activated GC in a dose-dependent manner from 100 microM to 1 mM without significant effects on NOS. H2O2-induced GC activation was blocked by catalase. These results suggested that oxygen radicals inhibited NOS and GC, but H2O2 could activate GC directly.
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PMID:The effects of oxygen radicals on the activity of nitric oxide synthase and guanylate cyclase. 989 52


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