SEARCH · PubMed Health

Results for “Sodium Azide”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources

PubMed1997

Analysis and assessment of the capacity of neutrophils to produce reactive oxygen species in a 96-well microplate format using lucigenin- and luminol-dependent chemiluminescence.

The chemiluminescence (CL) assay has been used to measure the reactive oxygen species (ROS)-generating capacity of phagocytes. To achieve more optimal measurement conditions for a multi-channel microplate photon-counting CL analyzer with the cooled charge-coupled device (CCD) camera which offers enhanced sensitivity, we investigated factors affecting the variability in lucigenin-dependent CL (LgCL) measurement of human neutrophils stimulated with either opsonized zymosan (OZ) or phorbol myristate acetate (PMA). We obtained sensitive LgCL responses with good reproducibility and rapid data-acquisition using 50 microl neutrophils (3 X 10(6) cells/ml) and 50 microl of 0.5 mM lucigenin per well, in addition to either 100 microl of OZ (5 mg/ml) when zymosan was opsonized with 10-20% serum or 100 microl of PMA solution (1 X 10(-6) M) with automatic regular intervals of mixing and detection during the continuous measurement at 37 degrees C. Furthermore, we studied the contribution of various ROS to LgCL and luminol-dependent CL (LmCL) using modulators of ROS metabolism including superoxide dismutase (SOD), catalase, deferoxamine and sodium azide (NaN3). LgCL was inhibited by SOD but not by the other agents, whereas LmCL was inhibited by NaN3 and deferoxamine. Thus, it was demonstrated that LgCL detects the superoxide anion with high selectivity whereas the LmCL assay measures myeloperoxidase (MPO)-mediated formation of hypochlorous acid. Such microplate-based multiple measurements facilitate the accurate assessment of phagocytic function.

Acridines↗

PubMed1998

Entry of African swine fever virus into Vero cells and uncoating.

African swine fever virus (ASFV) enters Vero cells by adsorptive endocytosis [Valdeira, M.L., Geraldes, A., 1985. Morphological study on the entry of African swine fever virus into cells, Biol Cell. 55, 35-40]. Electron microscopy of a lysosomotropic drug-controlled penetration indicated that this step takes place in the endosomes, after fusion between the viral envelope and the limiting membrane of the endosome. Inhibition studies with colcemid, cytochalasin B, sodium azide, dinitrophenol, lysosomotropic weak bases, and the ionophore monensin, showed that the virus uptake is largely independent of cytoskeletal and lysosomal function, but dependent on oxidative phosphorylation. Some protease inhibitors inhibited viral replication at an early step, indicating that the initiation of infection depends on a viral proteolytic cleavage.

2,4-Dinitrophenol↗

PubMed2000

Chronic ethanol ingestion increases efficiency of oxidative phosphorylation in rat liver mitochondria.

The efficiency of oxidative phosphorylation was compared between rats chronically fed with ethanol and controls. (i) Results showed that the liver mitochondria state 4 respiratory rate was strongly inhibited, while the corresponding proton-motive force was not affected; (ii) the cytochrome oxidase content and activity were decreased and (iii) the oxidative-phosphorylation yield was increased in the ethanol exposed group. Furthermore, oxidative phosphorylation at coupling site II was not affected by ethanol. Cytochrome oxidase inhibition by sodium-azide mimicked the effects of ethanol intoxication in control mitochondria. This indicates that the decrease in cytochrome oxidase activity induced by ethanol intoxication directly increases the efficiency of oxidative phosphorylation.

Alcohol Drinking↗

PubMed2003

Inhibition of energy metabolism down-regulates the Alzheimer related presenilin 2 gene.

Defects in energy metabolism and oxidative stress play an important role in the pathogenesis of Alzheimer's Disease (AD). In sporadic AD cases, presenilin 2 (PS2) mRNA levels are decreased in brain areas affected by the disease. The aim of the present study was to investigate whether mitochondrial dysfunction might influence PS2 gene expression. We demonstrated that the inhibition of energy metabolism by sodium azide down-regulates PS2 gene expression through modification of promoter activity. No one of the analyzed transcription factors, sensitive to redox status of the cell, could explain this effect. Azide effect on PS2 expression was completely inhibited by the addition of an antioxidant suggesting that the imbalance of the cellular redox homeostasis modulates the expression of this gene.

Alzheimer Disease↗

PubMed2006

Modeling cytoplasmic release of encapsulated oligonucleotides from cationic liposomes.

Transfection activity of antisense oligodeoxynucleotides (ODN)-loaded cationic liposomes is mainly restricted by uptake and ODN release into cytoplasm, which is difficult to evaluate in cell culture studies. Well-designed models of cellular membranes, aim of the present study, might facilitate investigation of such processes. In this investigation, a phosphorothioate ODN was actively encapsulated in a DODAP-containing cationic liposome by ethanol injection with 73% efficiency. ODN release was determined by fluorescence dequenching of FITC-ODN upon incubation of liposomes with early endosomal (EE), late endosomal (LE) and plasma membranes (PM) models. LE provided the highest release (up to 76%) in a temperature-dependent manner. Release by EE (<16%), total PM (<11%) and PM external layer ( approximately 0) were not temperature sensitive. These differences are attributed to lipid charge, chain mobility, critical packing parameter and cholesterol content of the models. Intracellular distribution of FITC-ODN, determined by fluorescence microscopy and flowcytometry in the presence and absence of sodium azide, confirmed that liposomes were internalized mainly via endocytosis; hence inability of our PL models to simulate such active processes. Instead, release of ODN from endosomes into cytoplasm was pH-sensitive and in good agreement with model membrane studies in terms of amount and mechanism.

Animals↗

PubMed1999

CD147 monoclonal antibodies induce homotypic cell aggregation of monocytic cell line U937 via LFA-1/ICAM-1 pathway.

CD147 is a 50 000-60 000 MW glycoprotein of the immunoglobulin superfamily broadly expressed on haemopoietic cell lines and peripheral blood cells. In the present study, six monoclonal antibodies (mAbs) directed against the CD147 protein were generated. The antigen defined by the generated CD147 mAbs is widely expressed on haemopoietic cell lines, peripheral blood cells and is a lymphocyte activation-associated cell surface molecule. The generated CD147 mAbs precipitated a broad protein band from U937 cells of 45 000-65 000 MW under reducing conditions. Functional analysis indicated that the CD147 mAbs markedly induced homotypic cell aggregation of U937 cells, but not K562 cells. The CD147 mAb-induced cell aggregation was inhibited by leucocyte function-antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) mAbs. However, the expression of LFA-1 and ICAM-1 molecules on U937 was not altered by CD147 mAb treatment. The U937 cell aggregation induced by CD147 mAb was also inhibited by ethylenediamine tetra-acetic acid (EDTA), sodium azide and when incubated at 4 degrees. We therefore propose that the binding of CD147 mAb to CD147 molecule, which mimics the natural ligand binding, may generate intracellular signals that activate LFA-1/ICAM-1 intercellular adhesion pathway.

Animals↗

PubMed2005

Antioxidant properties of cystic fibrosis sputum.

Oxidative stress is a likely contributor to the pathogenesis of cystic fibrosis (CF) lung disease. However, hydrogen peroxide (H(2)O(2)), a physiological oxidant, is not elevated in CF exhalates. H(2)O(2) may be neutralized by antioxidants in CF airway secretions. The H(2)O(2)-detoxifying capacity of CF airway secretions, obtained via sputum induction, was studied in an in vitro H(2)O(2) cytotoxicity model. 16HBE14o- cells were exposed to H(2)O(2) in culture medium containing either 0 or 10% fetal bovine serum (FBS) or 10% CF sputum supernatant (extracted without use of dithiothreitol). The efficiency of H(2)O(2) neutralization was estimated by measuring intracellular oxidant levels (dihydrorhodamine 123) after 2 h and cell viability (propidium iodide) after 24 h of H(2)O(2) exposure. Furthermore, the presence of reduced thiols (DTNB assay) and reduced glutathione (recycling assay) in CF sputum samples was evaluated. CF sputum extracts completely prevented intracellular oxidant accumulation seen in cells incubated with H(2)O(2) in both control media (i.e., 0 or 10% FBS). Furthermore, CF sputum abolished cell death in 16HBE14o- cells exposed to up to 1 mM H(2)O(2). In contrast, there was 100% cytotoxicity in cells exposed to 600 microM H(2)O(2) in both control media. The H(2)O(2)-detoxifying potential of CF sputum was sustained after catalase and heme peroxidases were inactivated by sodium azide, which does not affect glutathione peroxidase. In addition, reduced protein thiols were found in abundance in CF sputum. In conclusion, CF sputum is capable to neutralize H(2)O(2) and abundant reduced thiols and/or glutathione peroxidase are fully sufficient to detoxify H(2)O(2).

Adult↗

PubMed2006

The increase in the number of accessible SH-groups in the enterococcal membrane vesicles by ATP and nicotinamide adenine dinucleotides.

The number of accessible SH groups was determined in membrane vesicles prepared from Enterococcus hirae grown under anaerobic conditions at alkaline pH (pH 8.0). Addition of ATP or nicotinamide adenine dinucleotides (NAD(+) +NADH) to the vesicles caused a approximately 4-fold or approximately 1.9-fold increase in the number of SH-groups, respectively. This was inhibited by treatment with N-ethylmaleimide. The increase was significant when ATP and NAD(+) +NADH both were added. The change was lacking in the presence of the F0F1-ATPase inhibitors N,N'-diclohexylcarbodiimide or sodium azide. This was also absent in atp mutant with defect in the F0F1-ATPase and, in addition, it was less in potassium ion-free medium. These results are correlated with data about K+-dependent F0F1-ATPase activity, suggesting a relationship between the F0F1-ATPase and K+ uptake Trk-like system. The latter may be regulated by NAD or NADH mediating conformational changes.

Adenosine Triphosphate↗

PubMed2005

Visualization of the endocytic pathway in the filamentous fungus Aspergillus oryzae using an EGFP-fused plasma membrane protein.

Endocytosis is an important process for cellular activities. However, in filamentous fungi, the existence of endocytosis has been so far elusive. In this study, we used AoUapC-EGFP, the fusion protein of a putative uric acid-xanthine permease with enhanced green fluorescent protein (EGFP) in Aspergillus oryzae, to examine whether the endocytic process occurs or not. Upon the addition of ammonium into the medium the fusion protein was internalized from the plasma membrane. The internalization of AoUapC-EGFP was completely blocked by sodium azide, cold, and cytochalasin A treatments, suggesting that the internalization possesses the general features of endocytosis. These results demonstrate the occurrence of endocytosis in filamentous fungi. Moreover, we discovered that the endosomal compartments appeared upon the induction of endocytosis and moved in a microtubule-dependent manner.

Actins↗

PubMed1999

Redox-dependent and redox-independent subcomponents of protein degradation in perfused myocardium.

The integration of proteolytic pathways with metabolism was investigated in perfused rat myocardium. After a 10-min incorporation period, the minute-to-minute release of [3H]leucine from myocardial proteins was measured in nonrecirculating effluent perfusate. The nontoxic pro-oxidant probe diamide (100 microM) or a supraphysiological concentration of the endogenous oxidative metabolite dehydroascorbic acid (200 microM) reversibly inhibited 75% of myocardial proteolysis consisting of several known subcomponents (redox dependent); however, 25% of proteolysis was diamide insensitive (redox independent). Decrease in extracellular glucose concentration from 10 to 0.1 mM strongly increased the potencies of minimally effective concentrations of diamide (10 microM) or dehydroascorbic acid (15 microM) by approximately 10-fold to the respective potencies maximally inhibiting proteolysis. The reversal of diamide action was also strongly dependent on the perfusate glucose concentration observed at 0.1, 0.2, 1.0 and 10 mM glucose. Proteolytic inhibition caused by diamide (100 microM) was not accompanied by change in basal tissue ATP content of 5 micromol/g wet wt. Conversely, nearly lethal 60% ATP depletion caused by sodium azide (0.4 mM) was not accompanied by change in total [3H]leucine release. Results indicate that a large proteolytic subcomponent (75%) is maintained by redox chains fed by glucose; however, there is no apparent linkage of this proteolysis to short-term ATP fluctuations. A distinct major proteolytic subcomponent (25%) does not vary in response to experimental intervention in either ATP content or redox chains.

Adenosine Triphosphate↗

PubMed2001

Study of mycoloyl transferase transport across the cell envelope of Corynebacterium glutamicum.

PS1 is a major exported protein of Corynebacterium glutamicum homologous to mycobacterial antigen 85. It is largely associated with the mycolic acid-containing cell wall and acts as a mycoloyl transferase. The transport of PS1 to the cell wall is slow and occurs through two energetically distinct steps: the first one, which includes processing by signal peptidase, is rapid and inhibited by sodium azide or carbonyl cyanide m-chlorophenylhydrazone. This step is probably associated with translocation across the cytoplasmic membrane. The kinetics of the second step depend on the size of the polypeptide chain to be transported but neither ATP nor proton motive force is required. This step may correspond to the diffusion of PS1 across the cell wall to its final location.

Acyltransferases↗

PubMed2005

Protein modification caused by a high dose of gamma irradiation in cryo-sterilized plasma: protective effects of ascorbate.

Gamma irradiation is a method of pathogen inactivation in plasma derivatives currently under development. Gamma rays inactivate all known blood-borne viruses. However, the virucidally effective dose of radiation may affect the integrity and function of plasma proteins. Biological activity recoveries of the therapeutic products were shown to be significantly improved by lowering the irradiation temperature and by the addition of antioxidants; the mechanisms responsible for this have not been elucidated yet. Here we sterilized human plasma by gamma irradiation (50 kGy), on dry ice, in the presence (or absence) of ascorbate. The subsequent protein oxidation was quantified by a ferric-xylenol orange (hydroperoxides) and by DNPH-coupled assays (carbonyls). We demonstrated for the first time that irradiation of frozen plasma (without saturation with oxygen) resulted in the generation of protein hydroperoxides, the yield of which was dramatically decreased when plasma was irradiated in the presence of either sodium azide or ascorbate. In irradiated plasma the concentration of protein carbonyls was twofold higher than in nonirradiated control. Ascorbate significantly inhibited protein carbonylation. We concluded that freezing of plasma during irradiation does not provide the complete protection against protein carbonylation and hydroperoxide generation. Addition of ascorbate and some nontoxic metabolic inhibitors might be useful as protecting stabilizers.

Antioxidants↗

PubMed2005

Reactive oxygen species mediate lethality induced by far-UV in Escherichia coli cells.

The involvement of reactive oxygen species (ROS) in the induction of DNA damage to Escherichia coli cells caused by UVC (254 nm) irradiation was studied. We verified the expression of the soxS gene induced by UVC (254 nm) and its inhibition by sodium azide, a singlet oxygen (1O2) scavenger. Additional results showed that a water-soluble carotenoid (norbixin) protects against the lethal effects of UVC. These results suggest that UVC radiation can also cause ROS-mediated lethality.

Bacterial Physiological Phenomena↗

PubMed2002

Ketoprofen-induced intestinal permeability changes studied in side-by-side diffusion cells.

It is known that non-steroidal anti-inflammatory drugs (NSAIDs) increase intestinal permeability. Increased intestinal permeability is believed to result from the opening of tight junctions because of NSAID-induced reduction of prostaglandin synthesis and/or energy-depletion. In this study, ketoprofen-induced changes in intestinal permeability were evaluated by measuring tissue electrical parameters, namely tissue electrical resistance (TER), short circuit current (I(sc)) and transepithelial potential difference (PD), and the transport of a paracellular marker, fluorescein, across rat jejunum in-vitro. Ketoprofen, added to the mucosal side of the tissue, decreased TER and increased fluorescein transport in a concentration-dependent manner. I(sc) values and the active transport of D-glucose were not affected at ketoprofen concentrations of less than 5 mM. Higher ketoprofen concentrations decreased I(sc) values and diminished active transport of D-glucose, while transport of fluorescein increased markedly. Similar effects on intestinal properties were observed when the metabolic inhibitor sodium azide was added to the incubation medium. The results of this study suggest that the increased intestinal permeability observed at lower ketoprofen concentrations (< 5 mM) is most probably a consequence of reduced prostaglandin tight junction control, whereas at higher concentrations, ATP depletion caused by ketoprofen seems to be the major mechanism for increased intestinal permeability.

Algorithms↗

PubMed2002

Characterization of an inducible citrate uptake system in Penicillium simplicissimum.

When citrate was used as a sole source of carbon, citrate uptake by Penicillium simplicissimum increased 267-fold (if glucose-grown mycelium was adapted to citrate) or 1400-fold (if the fungus was grown on citrate) compared to glucose-grown mycelium. Inhibition of macromolecular synthesis prevented this stimulation of citrate uptake. Citrate uptake by glucose-grown mycelium was low (0.0015 nmol min(-1) (mg DW)(-1)) and most probably due to diffusion of undissociated citric acid. Citrate-adapted mycelium had a K(M) of 65 micromol l(-1) and a V(max) of 0.34 nmol min(-1) (mg DW)(-1). In citrate-grown mycelium K(M) was 318 micromol l(-1) and V(max) was 8.5 nmol min(-1) (mg DW)(-1). Citrate uptake was inhibited by sodium azide and uncouplers (TCS, 3,3',4',5-tetrachlorosalicylanilide; FCCP, carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone). Because of this we postulate that the induced citrate uptake must be an active transport process. The pH optimum of citrate uptake was between pH 6 and 7. EDTA and Mg2+, Mn2+, Cu2+, Zn2+, Fe2+, Ca2+ only weakly influenced the induced citrate uptake. The properties of citrate uptake by Aspergillus niger and P. simplicissimum are compared.

Biological Transport↗

PubMed2006

UVA1 radiation (340-400 nm) interferes with the perforin-granule system of CD8hi+ cytotoxic T lymphocytes in vitro.

UVA1-irradiation was introduced as an innovative and effective phototherapy of atopic dermatitis (AD) and other skin diseases. In AD, a defect of a central apoptosis inducing effector system involved in immunoregulation and immune defense, i.e., the system of perforin-granules in cytotoxic T lymphocytes (CTL), was recently reported: perforin-reduction and perforin-hyperreleasability. We now investigated UVA1-effects on the perforin-granule system in vitro. Peripheral blood CTLs were exposed in vitro to 10-100 J/cm2 UVA1 (340-400 nm), and to 30-150 mJ/cm2 UVB (280-315 nm) as a control. A time-dependent perforin-granule release was induced by phorbol 12-myristate 13-acetate (PMA) and ionomycin. This release was inhibited dose-dependently by UVA1, but not by UVB. An UVA1-dose dependent pattern of sensitive (80%) and insensitive (20%) individuals was found. The kinetics of perforin release in AD-CTLs, i.e. hyperreleasability, was normalized by 50 J/cm2 UVA1 in vitro. Sodium azide as a quencher of reactive oxygen species prevented the UVA1-mediated inhibition of perforin-granule release. Our data demonstrate for the first time a dose- and wavelength-dependent UVA1-effect in vitro on a major effector system of cytotoxic lymphocytes, the system of perforin-granules. This might contribute to the further understanding of immunomodulatory UVA1-effects in vivo.

CD8-Positive T-Lymphocytes↗

PubMed2006

Ecto-nucleotide pyrophosphatase/phosphodiesterase as part of a multiple system for nucleotide hydrolysis by platelets from rats: kinetic characterization and biochemical properties.

In this study, we describe an ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) activity in rat platelets. Using p-nitrophenyl 5'-thymidine monophosphate (p-Nph-5'-TMP) as a substrate for E-NPP, we demonstrate an enzyme activity that shares the major biochemical properties described for E-NPPs: alkaline pH dependence, divalent cation dependence and blockade of activity by metal ion chelator. K(m) and V(max) values for p-Nph-5'-TMP hydrolysis were found to be 106 +/- 18 microM and 3.44 +/- 0.18 nmol p-nitrophenol/min/mg (mean +/- SD, n = 5). We hypothesize that an E-NPP is co-localized with an ecto-nucleoside triphosphate diphosphohydrolase and an ecto-5'-nucleotidase on the platelet surface, as part of a multiple system for nucleotide hydrolysis, since they can act under distinct physiological conditions and can be differently regulated. Thus, 0.25 mM suramin inhibited p-Nph-5'-TMP, ATP and ADP hydrolysis, while 0.5 mM AMP decreased only p-Nph-5'-TMP hydrolysis. Besides, 5.0, 10 and 20 mM sodium azide just inhibited ATP and ADP hydrolysis. Angiotensin II (5.0 and 10 nM) affected only ADP hydrolysis. Gadolinium chloride (0.2 and 0.5 mM) strongly inhibited the ATP and ADP hydrolysis. The E-NPP described here represents a novel insight into the control of platelet purinergic signaling.

Adenosine Diphosphate↗

PubMed2005

Dual role of vitamin C in an oxygen-sensitive system: discrepancy between DNA damage and cell death.

Although vitamin C is considered to act both as pro-oxidant and antioxidant, the mechanisms underlying these actions are still unclear. Using the oxygen-sensitive system of a strict anaerobe, Prevotella melaninogenica, we investigated both the pro-oxidant and antioxidant mechanisms of vitamin C. In the presence of vitamin C, the 8-hydroxydeoxyguanosine (8OHdG) formation induced by oxygen exposure was enhanced, probably due to the action of vitamin C on hydrogen peroxide generated during oxygen exposure: while catalase almost completely suppressed the enhancing effect of vitamin C, 8OHdG formation induced by hydrogen peroxide was enhanced by vitamin C. By contrast, the presence of vitamin C inhibited bacterial cell death, membrane damage, and lipid peroxidation induced by oxygen exposure. Sodium azide showed similar effects to vitamin C, thus the antioxidant action of vitamin C may be due to its quenching of the singlet oxygen generated in this system. Both the pro-oxidant and antioxidant effects of vitamin C were observed only in acidic conditions.

8-Hydroxy-2'-Deoxyguanosine↗