186,307 research outputs found
Studies on the nature and activation of O2- -forming NADPH oxidase of leukocytes. II. Relationships between phosphorylation of a component of the enzyme and oxidase activity
No full textThe activation of O2- -formation by neutrophil NADPH oxidase is associated with phosphorylation of several membrane and cytosolic proteins. In the membranes a phosphoprotein of 32 kDa belonging to the NADPH oxidase-cytochrome b-245 system (P. Bellavite et al., Free Rad. Res. Commun., 1, 11 (1985] showed the highest relative increase of 32Pi incorporation. Concomitant with the phosphorylation, a shift of the apparent molecular mass of the protein from 31 to 32 kDa occurred. The time-course, the sensitivity to trifluoperazine and the dose-dependence of phosphorylation were similar to those of O2- forming activity, except that the latter showed a longer lag-time than the former. The increase of the 32 kDa phosphoprotein was also comparable to the kinetics of cytochrome b-245 reduction by anaerobically activated neutrophils. The phosphorylation and the NADPH oxidase were triggered by various stimulants including phorbol myristate acetate, opsonized zymosan, arachidonic acid and sodium fluoride. With arachido
Bewley and colleagues' quotation of review is selective.
No full textRelevant Article
Letter:
Advice on homoeopathic products: Authors’ reply to Fisher and 47 colleagues
Susan Bewley, On behalf of Edzard Ernst, John Garrow, Nick Ross, Les Rose, Michael Baum, James May, Alain Braillon, David Bender
BMJ 2011;343:doi:10.1136/bmj.d6693 (Published 18 October 2011
Catalase deficiency in myeloperoxidase deficient polymorphonuclear leucocytes from chicken
No full textRespiratory response of phagocytes: terminal NADPH oxidase and the mechanisms of its activation
No full textThe chemical composition, properties and activation mechanism of the
O2(-)-forming NADPH oxidase of phagocytes were investigated, using partially
purified enzyme preparations. Highly active NADPH oxidase was extracted as an
aggregate of high Mr from the membranes of neutrophils and macrophages. The
enzyme complex contained phospholipids and cytochrome b-245, very little FAD and
almost no quinones or NAD(P)H-dye reductase activity. The purification of a
polypeptide with a relative molecular mass of 31 500 strictly paralleled the
purification of NADPH oxidase, suggesting that this polypeptide is a component of
the enzyme. This protein was identified as cytochrome b -245 after dissociation
of the proteolipid complex and purification of the cytochrome moiety. The 31 500
Mr protein was phosphorylated in enzyme preparations from activated but not from
resting cells. The results indicate that: cytochrome b-245 is a major component
of NADPH oxidase; the involvement of NAD(P)H dye reductases in the O2(-)-forming
activity is questionable; the cytochrome b-245: FAD ratio in the enzyme complex
is much higher than that indicated in crude preparations; the Mr of pig
neutrophil cytochrome b-245 is 31 500; the activation of the O-2-forming system
involves a process of phosphorylation of cytochrome b-245
Il dolore e la medicina. Alla ricerca di senso e di cure
No full textRaccolta di saggi sul problema del dolore e del suo significato per la medicina visto da diverse prospettive: medica, filosofica e religiosa. Si insiste in particolare sulla necessità di una medicina che sappia considerare tutta la persona umana, anche nello stesso processo di diagnosi e cura delle malatie, tenendo nella dovuta considerazione l'influenza dei fattori psicologici e spirituali sulla genesi e il decorso delle malattie e sulla loro guarigione
Homeopathy and the science of high dilutions: when to believe the unbelievable
No full textIn 1988, an editorial in journal Nature [1] titled “When to believe the unbelievable” observed that the famous high-dilution experiments by Benveniste’s group [2] had no physical basis and suggested that “prudent people should, for the time being, suspend judgment.” However, judgment was not suspended at all, but in the following weeks the authors were condemned and ridiculed for the alleged lack of replication of their findings. Twenty-four years later, although the idea that solutions beyond Avogadro’s constant may exhibit biological and pharmacological activity remains “unbelievable” to the common sense, things are changing dramatically. Several groups of researchers from countries all over the world are devoted to this puzzling subject, which has weighty implications not only for pharmacology (homeopathy) but also for biology, physics and the environmental sciences. The XXVI meeting of GIRI (International Research Group on Very-low dose and High-Dilution Effects), scheduled to take place in Florence on September 20-22, 2012, will present a growing body of evidence attesting to the effects of high dilutions (HD). The program is organized around four main axes: physicochemical features of HD, studies in plants and the field, clinical and veterinary evidence, and laboratory models
Studies on the NADPH oxidation by subcellular particles from phagocytosing polymorphonuclear leucocytes: evidence for the involvement of three mechanisms
No full text1. The NADPH-oxidizing activity of a 100 000 X g particulate fraction of the postnuclear supernatant obtained frm guinea-pig phagocytosing poymorphonuclear leucocytes has been assayed by simultaneous determination of oxygen consumption, NADPH oxidation and O2- generation at pH 5.5 and 7.0 and with 0.15 mM and 1 mM NADPH. 2. The measurements of oxygen consumption and NADPH oxidation gave comparable results. The stoichiometry between the oxygen consumed and the NADPH oxidized was 1:1. 3. A markedly lower enzymatic activity was observed, under all the experimental conditions used, when the O2- generation assay was employed as compared to the assays of oxygen uptake and NADPH oxidation. 4. The explanation of this difference came from the analysis of the effect of superoxide dismutase and of cytochrome c which removes O2- formed during the oxidation of NADPH. 5. Both superoxide dismutase and cytochrome c inhibited the NADPH-oxidizing reactin at pH 5.5. The inhibition was higher with 1 mM NADPH than with 0.15 mM NADPH. 6. Both superoxide dismutase and cytochrome c inhibited the NADPH-oxidizing reaction at pH 7.0 with 1 mM NADPH but less than at pH 5.5 with 1 mM NADPH. 7. The effect of superoxide dismutase at pH 7.0 with 0.15 mM NADPH was negligible. 8. In all instances the inhibitory effect of cytochrome c was greater than that of superoxide dismutase. 9. It was concluded that the NADPH-oxidizing reaction studied here is made up of three components: an enzymatic univalent reduction of O2; an enzymatic, apparently non-univalent, O2 reduction and a non-enzymatic chain reaction. 10. These three components are variably and independently affected by the experimental conditions used. For example, the chain reaction is freely operative at pH 5.5 with 1 mM NADPH but is almost absent at pH 7.0 with 0.15 mM NADPH, whereas the univalent reduction of O2 is optimal at pH 7.0 with 1 mM NADPH
Il dolore e la medicina. Alla ricerca di senso e di cure
No full textLa realtà del dolore e della sofferenza pone domande di varia natura alla medicina e le risposte della scienza, pur importanti, si integrano con altre riflessioni: il dolore, umanamente vissuto come contraddizione, appare ultimamente come un grande enigma, inscindibilmente legato al mistero dell’uomo e dell’esistenza stessa dell’universo. Questo libro raccoglie contributi di medici, filosofi e scienziati, di cui l’aspetto unificante è l’esigenza di un approccio capace di integrare tra loro le diverse dimensioni dell’atto clinico e dell’arte terapeutica, anziché contrapporle come è a lungo accaduto negli ultimi secoli e come spesso accade ancora. L’operatore sanitario è in prima linea nel “prendersi cura” della persona malata, cercando anche di eliminare o alleviare, con tutti i mezzi possibili, il dolore e la sofferenza. Ma per far questo nel modo migliore, oltre agli strumenti tecnici deve possedere quella sapienza che coglie il senso del sintomo e della malattia per l’intera persona, la quale con la richiesta di “salute” pone anche, più o meno consapevolmente, una domanda di “salvezza”. La prefazione del card. Angelo Scola, patriarca di Venezia, sottolinea come il volume sa individuare queste importanti sfide per la medicina del XXI secolo
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