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 721 records · Page 40Linked to original sources

PubMed1993

Localization and characterization of a parotid Ca(2+)-dependent ecto-ATPase.

Parotid acini were isolated and tested to further establish the presence of ecto-ATPase in the intact cells. Inhibitors were used to determine if the inhibitor profile of the ATPase was similar to that of a Ca(2+)-ATPase from parotid membranes identified previously as an ecto-ATPase. The Ca(2+)-ATPase of intact cells was insensitive to oligomycin (10 micrograms/ml), N-ethylmaleimide (NEM) (0.1 mM), ruthenium red (0.1 mM), sodium azide (1 mM), and was inhibited approximately 22% by sodium orthovanadate (Na3VO4) (1 mM). This profile was similar to the Ca(2+)-ATPase of intact cells. Trifluoperazine (TFP) (0.1 mM) inhibited the enzyme in intact cells by approximately 32%. The nucleotide substrate specificity of the enzyme also reflected very closely the pattern seen in isolated membranes.

Adenosine Triphosphatases↗

PubMed1991

A new fluorescence method to detect singlet oxygen inside phospholipid model membranes.

A fluorescence method for detecting singlet oxygen (1O2) in model membranes is proposed. 1O2 was generated by hydrogen peroxide/sodium hypochlorite system. 1,3-Diphenylisobenzofuran (DPBF), a specific 1O2 trap, dissolved in organic solvents gives a strong fluorescence spectrum when excited at 410 nm. A similar spectrum, with a maximum at 455 nm, is obtained when DPBF is incorporated in unilamellar dipalmitoylphosphatidylcholine liposomes. The intensity of fluorescence spectrum decreases when DPBF-labeled liposomes are exposed to singlet oxygen. This decrease is sensitive to 1O2 traps and quenchers like tryptophan and sodium azide, to lipid membrane fluidity and to the concentration of sodium hypochlorite and hydrogen peroxide.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1986

Evidence that the antitumor agent hydroxyurea enters mammalian cells by a diffusion mechanism.

Very little information is available about the process responsible for the uptake of the antitumor agent hydroxyurea by mammalian cells. Therefore we have investigated the transport of hydroxy[14C]-urea into Chinese hamster ovary cells. Using a convenient and reproducible 2 min. assay we found that hydroxyurea was taken up in a linear nonsaturable fashion between 0.01 mM and 100 mM drug. The Km for hydroxyurea uptake was essentially zero and the Vmax appeared to be infinite, suggesting a diffusion mechanism. The observation that intracellular drug concentrations were consistently less than medium concentrations indicated that uptake was not an active process. Experiments performed with the metabolic inhibitor sodium azide, and investigations at different assay temperatures also gave results consistent with a mechanism of drug diffusion. In total, the results obtained in this study are in agreement with the proposal that hydroxyurea enters the cell primarily by a process of diffusion. These observations provide a more complete understanding of the mode of action of this widely used drug.

Animals↗

PubMed1991

Detection of Streptococcus suis type 2 in tonsils of slaughtered pigs using improved selective and differential media.

New selective and differential media were devised for the isolation and identification of Streptococcus suis type 2. The selective medium (NNCC) agar) was Todd-Hewitt broth containing 1.5% Bactoagar and 5% defibrinated sheep blood with addition of sodium azide (50 micrograms/ml), nalidixic acid (25 micrograms/ml), colistin (12.5 micrograms/ml) and crystal violet (2 micrograms/ml). The differential medium consisted of heart infusion agar and antiserum specific only for S. suis type 2. In a total of 291 pigs tested by a combination of these media, S. suis type 2 was isolated and confirmed from 40 of them (13.7%).

Agar↗

PubMed1985

Ligand-induced changes in the location of actin, myosin, 95K (alpha-actinin), and 120K protein in amebae of Dictyostelium discoideum.

In this study we investigated concanavalin A (Con A) induced changes in the locations of actin, myosin, 120K, and 95K (alpha-actinin) to determine the extent to which actin and myosin are reorganized during capping and the roles that 120K and 95K might play in this reorganization. We observed the location of each protein by indirect immunofluorescence using affinity purified antibodies. Four morphological states were distinguished in vegetative Dictyostelium amebae: ameboid cells before Con A binding, patched cells, capped cells, and ameboid cells with caps. The location of each protein was distinct in ameboid cells both before and after capping Actin and 120K were found in the cell cortex usually associated with surface projections, and myosin and 95K were diffusely distributed. Myosin was excluded from surface projections in ameboid cells. During patching, all four proteins were localized below Con A patches. During capping, actin, myosin, and 95K protein moved with the Con A patches into the cap whereas 120K protein was excluded from the cap. During the late stages of cap formation actin and myosin were progressively lost from the cap, and 120K became concentrated in new actin-filled projections that formed away from the cap. However, 95K remained tightly associated with the cap. Poisoning cells with sodium azide inhibited capping but not patching of ligand. In azide-poisoned cells, myosin and 95K did not co-patch with Con A, whereas copatching of 120K and actin with Con A occurred as usual. Our results support the hypothesis that capping is an actomyosin-mediated motile event that involves a sliding interaction between actin filaments, which are anchored through the membrane to ligand patches, and myosin in the cortex. They are also consistent with a role for 120K in the formation of surface projections by promoting growth and/or cross-linking of actin filaments within projections, and with a role for 95K in regulating actomyosin-mediated contractility, earlier proposals based on the in vitro properties of these two proteins (Condeelis, J., M. Vahey, J. M. Carboni, J. DeMey, S. Ogihara, 1984, J. Cell Biol., 99:119s-126s).

Actinin↗

PubMed1988

Increase of enzyme activities following the in vitro peroxidation of normal human red blood cells.

Red blood cells (RBCs) from 15 normal human blood samples were incubated with different concentrations of hydrogen peroxide in sodium azide, and the effects of the peroxidation on several glycolytic and nucleotidic enzyme activities were investigated. The release of malonyl dialdehyde (MDA) and methemoglobin formation were used as indicators of RBC peroxidation. The increase of H2O2, final concentration from 0.1 to 5 mmol/l, resulted in a progressive rise of almost all glycolytic enzyme activities, especially those of aldolase (200% of normal at 1 mmol/l), phosphoglycerate kinase (140%), phosphoglycerate mutase (136%), pyruvate kinase (130%) and glutathione peroxidase (130%), and in a decrease of glucose-6-phosphate dehydrogenase (68%) and pyrimidine-5-nucleotidase (23%). The addition of beta-mercaptoethanol to the incubation medium abolished only the effect of 1 mmol/l H2O2 on glucose-6-phosphate dehydrogenase.

Azides↗

PubMed1989

[Inactivation of concentrated biomasses of Rickettsia prowazekii].

The methods used for the sparing inactivation of highly concentrated R. prowazekii biomass and for the decrease of its infectious activity are described. These methods are recommended for use in experiments in the field of molecular biology, as well as for disinfection of different materials contaminated with rickettsiae. As conditions for complete inactivation, incubation at 50 degrees C for 1 hour without chemical disinfectants, treatment with 0.5% phenol solution at 30 degrees C for 12 hours and with 0.1% formaldehyde solution at 4 degrees C for 24 hours have been selected. Treatment with 0.5% phenol solution at 36 degrees C for 1 hour or incubation at 45 degrees C without the use of disinfectants ensures an essential decrease in the infectivity of the material if the work with viable infective agents is necessary. Ultraviolet irradiation for 1.5 hours and exposure to the action of 0.1-0.5% sodium azide are less effective.

Azides↗

PubMed1989

Modification of the FAST-ELISA for field diagnosis of schistosomiasis mansoni with serum or blood samples.

Using well-characterized serum pools from patients (with schistosomiasis mansoni), we modified the FAST-ELISA system for detecting serum antibodies to Schistosoma mansoni for field use. We found little or no change in test function or results when the test was run 1) with blood instead of serum, 2) after addition of sodium azide preservation to diluted and lysed blood specimens, 3) using impure water in wash steps, and 4) without a spectrophotometer (i.e., read with the naked eye). Our evaluation of the modified FAST-ELISA showed that it can be successfully used under the restraints of minimally equipped field laboratories.

Animals↗

PubMed1987

Mechanisms of azide induced increases in the c-wave and standing potential of the intact cat eye.

The c-wave of the ERG and the standing potential of the eye both undergo increases in amplitude following intravenous infusions of sodium azide (NaN3), as first shown by Noell [Am. J. Physiol. 170, 217-238 (1952); U.S.A.F. School of Aviation Medicine, Project No. 21-1201-0004 (1953)]. We have studied the mechanism of these changes in the intact cat eye. Intraretinal and intracellular retinal pigment epithelial (RPE) cell recordings show that most of the change occurs at the RPE, but that there is a small direct effect on the neural retina. The increase of standing potential is caused by a depolarization of the basal membrane of the RPE, and the increase in c-wave amplitude results from a decrease in basal membrane resistance that accompanies the depolarization. This relation between basal membrane potential and resistance is similar to that observed during hypoxia and during the light peak of the d.c. ERG.

Animals↗

PubMed1975

The basal apparatus. Mass isolation from the molluscan ciliated gill epithelium and a preliminary characterization of striated rootlets.

The basal apparatus, consisting of an array of interconnected basal bodies bearing bifurcating striated rootlets encompassing a nucleus, has been isolated from hypertonically deciliated columnar gill epithelial cells of the bay scallop Aequipecten irradians through gentle lysis with Triton X-100. The rootlets, 8-10 mum in length, were not easily preserved with conventional electron microscope fixatives, suggesting that the extent of their contribution to cellular architecture has been somewhat underestimated, even though Englemann described many of the structural details of the basal apparatus in 1880. The striated rootlets were soluble at high but not at low pH, in 2 M solutions of sodium azide and potassium thiocyanate but not sodium or potassium chloride, in 1% deoxycholate but not digitonin, and in the denaturing solvents 6 M guanidine-HC1, 8 M urea, and 1% sodium dodecylsulfate at 100 degrees C. The protein found consistently when rootlets were solubilized migrated on SDS-polyacrylamide gels as a closely spaced doublet with apparent molecular weights of 230,000 and 250,000 daltons. This unique protein, distinct from tropocollagen or various muscle components, has been named ankyrin because of the rootlet's anchor-like function in the cell.

Animals↗

PubMed1990

Lysis of fibrillar collagen by neutrophils in synovial fluid. A role for surface-bound immunoglobulins.

Synovial fluids (SF) contain inhibitors capable of neutralizing the activity of proteases secreted by inflammatory cells and fibroblasts. To further define a potential role for SF polymorphonuclear neutrophils (PMN) in mediating joint destruction, peripheral blood PMN were suspended in SF and incubated with reconstituted collagen fibrils. Incubation of PMN-SF mixtures with collagen fibrils precoated with monomeric IgG resulted in significant lysis of the underlying fibrils relative to that seen with uncoated fibrils. Augmented fibril lysis by PMN-SF mixtures in which the PMN were activated with fluid-phase ligands such as phorbol myristate acetate or heat-aggregated IgG was not seen. Lysis of IgG-coated fibrils by PMN-SF was inhibited in the presence of EDTA or sodium azide. PMN-mediated resorption of fibrillar collagen occurred despite the presence of protease inhibitors in the SF at a concentration capable of neutralizing human neutrophil collagenase. These results suggest that the focal release and activation of human neutrophil collagenase during PMN stimulation by tissue-bound immunoglobulins may mediate the resorption of joint tissue collagens in rheumatoid arthritis, even in the presence of protease inhibitors.

Animals↗

PubMed1986

An examination of the oxidation of mercury vapor by rat brain homogenate.

The oxidation of mercury vapor (Hg degrees) to divalent inorganic mercury (Hg2+) was studied in rat brain homogenates. By using a "degassing" method, it was possible to speciate the mercury present in the homogenate and, for the first time, to measure the rate of oxidation as a function of the substrate (Hg degrees) concentration. Mercury oxidation was first-order with respect to substrate concentration at all concentrations tested, and the first-order rate constant for the oxidation process was proportional to homogenate concentration. The role of catalase compound I in mercury vapor oxidation by brain homogenate was examined by observing the effects of two inhibitors of catalase (catalase compound I) on homogenate mercury-oxidizing activity and catalase activity. Sodium azide (50 mM) completely inhibited both mercury-oxidizing activity and catalase activity. Aminotriazole (3-amino-1H-1,2,4-triazole) (50 mM) completely inhibited only mercury-oxidizing activity; some residual catalase activity was found in the aminotriazole-treated homogenate. It was concluded that catalase compound I plays a major role in the oxidation of Hg degrees, but the possibility that catalase-independent pathways make a minor contribution cannot be excluded.

Amitrole↗

PubMed2000

Ectonucleotide diphosphohydrolase activities in hemocytes of larval Manduca sexta.

In this work, we describe the ability of living hemocytes from an insect (Manduca sexta, Lepidoptera) to hydrolyze extracellular ATP. In these intact cells, there was a low level of ATP hydrolysis in the absence of any divalent metal (8.24 +/- 0.94 nmol of Pi/h x 10(6) cells). The ATP hydrolysis was stimulated by MgCl2 and the Mg2+-dependent ecto-ATPase activity was 15.93 +/- 1.74 nmol of Pi/h x 10(6) cells. Both activities were linear with cell density and with time for at least 90 min. The addition of MgCl2 to extracellular medium increased the ecto-ATPase activity in a dose-dependent manner. At 5 mM ATP, half-maximal stimulation of ATP hydrolysis was obtained with 0.33 mM MgCl2. This stimulatory activity was not observed when Ca2+ replaced Mg2+. The apparent Km values for ATP-4 and Mg-ATP2- were 0.059 and 0.097 mM, respectively. The Mg2+-independent ATPase activity was unaffected by pH in the range between 6.6 and 7.4, in which the cells were viable. However, the Mg2+-dependent ATPase activity was enhanced by an increase of pH. These ecto-ATPase activities were insensitive to inhibitors of other ATPase and phosphatase activities, such as oligomycin, sodium azide, bafilomycin A1, ouabain, furosemide, vanadate, sodium fluoride, tartrate, and levamizole. To confirm the observed hydrolytic activities as those of an ecto-ATPase, we used an impermeant inhibitor, DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid), as well as suramin, an antagonist of P2-purinoreceptors and inhibitor of some ecto-ATPases. These two reagents inhibited the Mg2+-independent and the Mg2+-dependent ATPase activities to different extents. Interestingly, lipopolysaccharide, a component of cell walls of gram-negative bacteria that increase hemocyte aggregation and phagocytosis, increased the Mg2+-dependent ecto-ATPase activity in a dose-dependent manner but did not modify the Mg2+-independent ecto-ATPase activity.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1992

A peroxidase-independent method for the quantitation of extracellular hydrogen peroxide generated by activated phagocytes in vitro.

A peroxidase-independent method for the determination of phagocyte-derived hydrogen peroxide in vitro is described. The method is based on the catalase-inhibitable oxidation of added cysteine. Human blood neutrophils (1 x 10(6)/ml) were coincubated with the myeloperoxidase (MPO) inhibitor, sodium azide (10 micrograms/ml), for 30 min at 37 degrees C followed by addition of phorbol 12-myristate 13-acetate (PMA, 10 ng/ml), a potent activator of membrane-associated oxidative metabolism. After incubation at 37 degrees C the cells were removed and the supernatants aliquoted and incubated with and without catalase (500 U/ml) for 10 min at room temperature followed by addition of cysteine (50 microM). Thereafter the catalase-inhibitable, H2O2-mediated oxidation of added cysteine was assayed spectrophotometrically following the addition of the thiol-reactive agent 5,5'-dithiobis-(2-nitrobenzoic acid), and the H2O2 concentration determined using a standard curve constructed from difference data based on the oxidation of cysteine by H2O2 (0-200 nmol). The average amount of H2O2 produced by 10(6) PMA-activated neutrophils was 47 +/- 7 nmol/30 min. This sensitive assay procedure is likely to be particularly useful for investigating the effects of pharmacological agents and anti-oxidant nutrients on H2O2 production by activated phagocytes, since these agents are generally unsuited for use in peroxidase-based assays.

Azides↗

PubMedDate not supplied

Processing and transfer of epidermal growth factor in developing rat jejunum and ileum.

Using everted sac technique we demonstrated the transfer of 125I-mEGF across the jejunal and ileal walls of suckling, weanling and adult rats. The transfer by the suckling rat jejunum and ileum was significantly inhibited by the presence of dinitrophenol and sodium azide or by the replacement of sodium with potassium or choline, RP-HPLC analysis detected carboxy-terminal processing of 125I-mEGF in suckling and adult rat jejunum and ileum. Suckling rat jejunum produced 125I-des(53)mEGF and 125I-des(49-53)mEGF, whereas 125I-des(48-53)mEGF was detected in suckling rat ileum or adult rat jejunum and ileum. All three forms of 125I-mEGF bound to anti-EGF antibody and EGF receptors. The receptor binding of 125I-des(53)mEGF was higher than that of 125I-mEGF, but those of 125I-des(49-53)mEGF and 125I-des(48-53)mEGF were greatly diminished. Results indicate a carboxy-terminal processing of mouse EGF during uptake and transfer in the small intestine of developing and adult rats, and the resulting products showed altered receptor binding. An identical amino acid sequence of the C-terminal pentapeptide of eGF from mouse, human and possibly rat may suggest a biological significance of C-terminal processing of EGF in the small intestine.

Animals↗

PubMed1991

Characterization of a synaptosomal ATP diphosphohydrolase from the electric organ of Torpedo marmorata.

A true ecto-apyrase (ATP diphosphohydrolase, EC 3.6.1.5) enzyme was found in the synaptosomal fraction from the electric organ of the electric ray Torpedo marmorata. The activity could not be attributed to the combined action of different enzymes. The pH requirement and calcium dependence were the same for hydrolysis of both substrates ADP and ATP. The enzyme had an apparent Km value of 117 microM for ATP and of 123 microM for ADP. The involvement of nonspecific phosphatases in the hydrolysis of both substrates was excluded. The enzyme hydrolyses almost equally well different nucleoside di- and triphosphates. ATP and ADP hydrolysis was not inhibited by seven ATPase inhibitors, i.e., sodium azide, dinitrophenol, ruthenium red, oligomycin, ouabain, sodium orthovanadate and lanthanum.

Animals↗

PubMed2004

Identification and functional characterization of a Na(+)-independent large neutral amino acid transporter (LAT2) on ARPE-19 cells.

The objective of this study was to investigate the presence of a large neutral amino acid transporter on the ARPE-19 cell line. ARPE-19 cells were grown on 24-well plates for uptake studies. Uptake characteristics of [3H]L-phenylalanine (L-Phe) were determined at various concentrations and pH at 37 degrees C. Inhibition studies were conducted in presence of L- and D-amino acids, metabolic inhibitors, like ouabain, sodium azide, and in presence of sodium-free medium, to delineate the mechanism of uptake. RT-PCR was carried out on total RNA isolated from the ARPE-19 cells. Presence of Na(+)-free buffer did reduce the uptake rate. Hence, all experiments were carried out in Na(+)-free medium to delineate the sodium-independent uptake mechanism. Uptake of L-Phe on ARPE cells was found to be saturable with a Km = 89.35 +/- 14 microM, Vmax = 58.9 +/- 2.5 pmol min(-1) mg protein(-1), and Kd = 0.108 +/- 0.04 microl min(-1) mg protein(-1). Dose-dependent inhibition was observed with increasing concentrations of unlabeled L-Phe. Uptake also was found to be energy independent. Significant inhibition of [3H]L-Phe was observed with large neutral aromatic and aliphatic amino acids as well as small neutral amino acids. System L-specific inhibitor BCH produced partial inhibition of uptake. Neither acidic nor basic amino acids altered the uptake rate. Results obtained were predominantly characteristic of LAT2, particularly with respect to substrate selectivity and pH dependence. Bands for LAT2 were detected by RT-PCR in the ARPE cell line. This study provides biochemical evidence of the presence of a Na(+)-independent, facilitative transport system, LAT2, on the ARPE-19 cells.

Amino Acid Transport System y+↗

PubMed1997

Calcium-induced bilirubin-dependent hemolysis of human erythrocytes.

Human erythrocytes, preincubated with different concentrations of calcium chloride (0.17-1.67 mM) showed hemolysis after addition of bilirubin (72 microM). Hemolysis was observed only when cells were incubated first with calcium followed by bilirubin and not vice versa. This hemolysis was found to be dependent upon several factors such as concentration of bilirubin, time of incubation of erythrocytes with calcium and time of incubation of bilirubin with the calcium-loaded erythrocytes. Inclusion of EDTA in the incubation medium reduced the percentage hemolysis to a significant extent. Involvement of activated oxygen species in hemolytic process seems to be unlikely as inclusion of sodium azide and catalase did not prevent hemolysis. A comparison of other bivalent cations such as Ba2+, Mg2+, Mn2+ and Cu2+ with Ca2+ for their ability to hemolyse cells in presence of bilirubin shows that Ba2+ and Mg2+ are ineffective, whereas both Mn2+ and Cu2+ induce hemolysis both in the absence as well as in the presence of bilirubin. However, their mechanism of hemolysis is different from that of calcium-induced hemolysis. Formation of calcium-induced hydrophobic aggregates of phospholipid molecules in erythrocyte membrane may open the new binding sites for bilirubin on these membranes which may perturb the membrane conformation.

Azides↗