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PubMed2005

Sodium azide and 2-deoxy-D-glucose-induced cellular stress affects phosphorylation-dependent AbetaPP processing.

Production of the amyloid beta (Abeta) peptide via altered metabolism of the amyloid beta-Protein Precursor (AbetaPP) appears to be a key event in the pathology of Alzheimer Disease (AD). Accordingly, altered processing of AbetaPP was observed under conditions of abnormal cellular stress induced by sodium azide in the presence of 2-deoxy-D-glucose (2DG). As previously reported, the production of sAbetaPP (the secreted fragment of AbetaPP) was inhibited. However, our data further suggests that 2DG alone can account for most of the observed effects on AbetaPP processing in COS-1 cells and PC12 cells. It appears that 2DG interferes with the normal glycosylation of AbetaPP and its maturation process, having direct consequences on sAbetaPP production. Interestingly, PMA (phorbol 12-myristate 13-acetate)-induced sAbetaPP production was maintained under the stress conditions used, suggesting that potential non-amyloidogenic AbetaPP processing can still be favoured. This is of potential therapeutic interest, since it indicates that even under adverse stress conditions drugs such as PMA can affect AbetaPP processing, leading to increased sAbetaPP production and a concomitant reduction in Abeta production. However, the induction of sAbetaPP production was not identical when the phosphatase inhibitor OA (okadaic acid) was used. In fact, the typical OA-induced increase in sAbetaPP production could be abolished under specific conditions. This constitutes an interesting precedent for the possible dissociation of the PMA and OA responses in terms of sAbetaPP production. The involvement of protein phosphatases, which are inhibited by OA, inbetaPP processing, was reinforced by the increased co-localization of AbetaPP and PP1alpha (protein phosphatase 1alpha) at the cell surface upon exposure to OA and PMA. Overall, our results support the notion that signal transduction processes may be of particular relevance for our understanding of the molecular basis of AD, and for the design of rational signal transduction therapeutics.

Adaptor Proteins, Signal Transducing↗
PubMed1975

Fatal self-administration of sodium azide.

A 19-year old woman ingested an unknown amount of sodium azide (NaN3). The earliest symptoms were nausea and loss of vision. Within a few hours her clinical features were dominated by central nervous system signs, acute pulmonary edema, lactic acidosis, and hypothermia. The patient died within 12 hours, hypotension and shock occurring as preterminal events. This was the first recorded case in which antidotal methemoglobin production was attempted. Sodium nitrite administration resulted in methemoglobinemia but did not appreciably alter the clinical course and may not be of major benefit. Gross examination post-mortem showed marked pulmonary edema, visceral hemorrhage and congestion, and slight cerebral edema. Microscopically, the lungs showed alveolar and interstitial edema and a polymorphonuclear infiltrate. There were petechial hemorrhages and severe nonspecific changes in the brain.

Adult↗
PubMed1980

SAMA/PMA position: safe disposal of laboratory wastes containing sodium azide.

While it is well established that the disposal of laboratory wastes containing sodium azide might be hazardous, evidence proving such a risk when the wastes are disposed of properly remains inconclusive. The Scientific Apparatus Makers Association and the Pharmaceutical Manufacturers Association oppose any general policy requiring the elimination of the preservative from laboratory reagents. Rather, they endorse the concept of alerting users to its presence and advising them of proper handling procedures. The following position paper, prepared by the SAMA/PMA Task Force, explains these suggestions.

Azides↗
PubMed1975

[Reaction of 1,8-naphthyridine azides with ethyl acrylate].

The reaction of 1,8-naphthyridine azides with ethyl acrylate leads to the formation of 2-pyrazolines instead of 1,2,3-triazolines. Some of the compounds obtained have undergone pharmacological and microbiological (antibacterial) testing.

Acrylates↗
PubMed1992

Prostaglandin photoaffinity probes: synthesis and binding affinity of C-18 substituted PGF2 alpha prostanoids bearing a perfluorinated aryl azide.

C-18 Phenoxy analogs of prostaglandin F2 alpha (PGF2 alpha) that possessed a perfluorinated aryl azide and an aryl iodide substituent were synthesized and evaluated as potential photoaffinity probes for PGF2 alpha. Prior studies indicated that only hydrophobic modifications in the omega-side chain of PGF2 alpha were compatible with high binding affinity, and this finding excluded the use of a hydroxyl-substituted C-18 phenoxy group as an activated aryl ring capable of radioiodination. Consequently, an alternate means of introducing the iodine substituent using an ipsosubstitution of a trimethylsilyl arene was developed. Although this strategy was successful from a synthetic perspective, the potential PGF2 alpha photoaffinity probe, (15S)-18-[3'-((4''-azido-2'',3'',5'',6''-tetrafluorophenyl)- methoxy) methyl-5'-iodophenoxy]-19,20-bisnorprostaglandin F2 alpha, exhibited only marginal competitive binding with [3H]-PGF2 alpha to ovine luteal cells and to plasma membranes of bovine corpora lutea. The hydrophobic but bulky C-18 substituent was presumably incompatible with effective receptor binding.

Affinity Labels↗
PubMed2002

[Changes of thioredoxin mRNA level in neurons insulted by sodium azide].

Oxidative stress has been considered to be associated with many neurodegenerative diseases, while mitochondrial damage is one of the important reasons that aggravate oxidative stress. Sodium azide (NaN3) is a specific inhibitor of mitochondrial cytochrome c oxidase (COX), which can be used to mimic neuronal damage induced by mitochondrial deficiency. In this experiment, the neurotoxic effects of NaN3 on cultured primary neurons were detected by means of cell viability measurement (MTT assay) and morphological observation, and an in vitro model of neuronal injury induced by NaN3 were established. Further the changes of thioredoxin mRNA level in cultured neurons insulted by NaN3 were analyzed by semiquantitative RT-PCR in order to explore the role of Trx, an important redox regulatory protein, in the process of neuronal injury. It was found that cultured neurons could be damaged by NaN3 in a dose- and time-dependent manner and the expression of Trx decreased during certain dose (0-32mmol/L) and time (0-4hr) of NaN3 treatment. The above data suggest that decreased the expression of Trx may be associated with oxidative stress induced by neuronal respiratory chain injury, which could impair neuronal protective mechanism.

Animals↗
PubMed2006

[Effect of prepared Polygonum multiflorum on striatum extracellular acetylcholine and choline in rats of intracerebral perfusion with sodium azide].

OBJECTIVE: To investigate the protection mechanism of prepared Polygonum multiflorum (PPMT) in rat brain with sodium azide (NaN3) perfusion. METHOD: Rats were divided into six groups: control, model, PPMT, Duxil and PPMT + Duxil groups. The intracerebral microdialysis and high performance liquid chromatography-post column Immobilized enzyme reactor-electrochemical detection were used to continuously measure extracellular acetylcholine (ACh) and choline (Ch) levels in striatum of freely moving awake rats. RESULT: The extracellular Ach, Ch levels of striatum stayed stable in the control group during the whole observing period, but the ACh levels in the model group were lower significant than that in the control group. The Ach levels of three drug groups were respectively higher significant than that of model group at some time points. While the extracellular Ch level in striatum of the model group increased singnificantly compared with the control group. The Ch levels of the three drug groups were lower significant than that of the model group respectively at certain time points. The effects of PPMT were similar with that of Duxil. CONCLUSION: The prepared P. multiflorum can improve the impaired cholinergic nerve function to exert the effects of brain protection by elevating extracellular Ach level and improving uptake of extracellular Ch. It may provide the experimental evidence to support the idea that P. multiflorum could be brain protective drug to treat retrogressive disease such as dementia.

Acetylcholine↗
PubMed1977

Increased intraocular pressure following topical azide or nitroprusside.

In rabbits the topical administration of sodium azide (NaNs) or sodium nitroprusside (SNP) increased intraocular pressure in a dose-response manner. These agents, which activate guanylate cyclase, elevated cyclic GMP in the aqueous humor. Systemic blood pressure and pulse were not altered. Tonographic outflow facility was unchanged, suggesting an increase in aqueous humor flow as the mechanism for the elevation of intraocular pressure. Posterior chamber aqueous humor ascorbate concentration was decreased in the eye receiving the NaN3 or SNP. Systemic pretreatment with phenoxybenzamine, an alpha-adrenergic blocking agent, prevented the elevation of intraocular pressure observed following NaN3 and SNP. Pretreatment with systemic indomethacin, propranolol, or acetazolamide or the topical application of atropine or epinephrine failed to alter the elevation of intraocular pressure by either NaN3 or SNP.

Administration, Topical↗
PubMed1991

Activation of 5-[125I]iodonaphthyl-1-azide via excitation of fluorescent (N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)) lipid analogs in living cells. A potential tool for identification of compartment-specific proteins and proteins involved in intracellular transport and metabolism of lipids.

We describe a new technique for analysis of proteins located near fluorescent lipid analogs in intact living cells using the membrane-permeant, photoactivatable probe, 5-[125I]iodonaphthyl-1-azide ([125I]INA). [125I] INA can be activated directly with UV light or indirectly through excitation of adjacent fluorophores (photosensitizers) with visible light to modify nearby proteins covalently with 125I. In this report we demonstrate that fluorescent phospholipids and sphingolipids containing N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-6-aminocaproic acid serve as appropriate photosensitizers for [125I]INA. Using Chinese hamster ovary fibroblasts, we optimized the labeling conditions with respect to lipid concentration and time of irradiation and then examined the profiles of cellular proteins that were labeled when fluorescent analogs of ceramide, sphingomyelin, and phosphatidic acid were used as photosensitizers in living cells. The use of different fluorescent lipids, which label different subcellular compartments of cells as determined by fluorescence microscopy, derivatized different sets of cellular proteins with 125I. The labeled proteins were subsets of the total set of proteins available for derivatization as determined by direct activation of [125I]INA. Most proteins labeled by this procedure were pelleted by centrifugation of cell lysates at high speed (260,000 x g), but several soluble proteins were also labeled under these conditions. The implications of using this technique for identification of compartment-specific proteins and proteins involved in lipid metabolism and transport are discussed.

4-Chloro-7-nitrobenzofurazan↗
PubMed1990

Mapping the alpha-subunit site photolabeled by the noncompetitive inhibitor [3H]quinacrine azide in the active state of the nicotinic acetylcholine receptor.

We have characterized the time-resolved labeling of a site on the Torpedo californica electrocyte acetylcholine receptor (ACHR) by the photoreactive noncompetitive inhibitor derivative quinacrine azide (QA). The dependence of [3H]QA labeling on acetylcholine (ACH) concentration and on time is consistent with the preferential labeling by [3H]QA of ACHR in the open state. The ACH-dependent [3H]QA labeling, which was associated predominantly with the alpha-subunit, was blocked by other noncompetitive inhibitors including quinacrine, chlorpromazine, proadifen, histrionicotoxin, and bupivacaine. alpha-Subunit from ACHR labeled with [3H]QA 20 ms after the addition of ACH was cleaved with CNBr, and the fragments were separated by high pressure liquid chromatography. A peptide containing a major site of specific labeling was purified on two different reverse-phase columns. By N-terminal sequencing, amino acid composition, binding to mercurial-agarose, and apparent molecular weight, this [3H]QA-labeled peptide was identified as alpha-208-243, a CNBr fragment containing the putative membrane-spanning helix M1.

Acetylcholine↗
PubMed1985

Time-resolved photolabeling by quinacrine azide of a noncompetitive inhibitor site of the nicotinic acetylcholine receptor in a transient, agonist-induced state.

Local anesthetics and other noncompetitive inhibitors (NCIs) of the nicotinic acetylcholine receptor, acting at sites other than the acetylcholine-binding sites, block channel opening and/or cation translation through the open channel. In order to characterize the NCI sites and to decide among possible mechanisms of NCI action, we have photolabeled the receptor in membrane from Torpedo electric tissue with the photolyzable NCI [3H]quinacrine azide ([3H]QA), using a continuous-flow, rapid-mixing device and millisecond-duration irradiation. Membrane, [3H]QA, and effectors were mixed, and, after delay times of 20 ms or greater, the mixture was irradiated for 2 ms, quenched, and collected. Brief exposure of the receptor to acetylcholine, but not to hexamethonium or d-tubocurarine, induced a state particularly susceptible to photoincorporation of [3H]QA. This acetylcholine-induced photoincorporation was exclusively into the alpha and beta chains of the receptor, peaked at 100-ms delay time, declined to 15% of maximum after delay times of minutes, and was blocked by the NCIs proadifen and histrionicotoxin. At 20-ms delay, the dependence of labeling by 2 microM [3H]QA on acetylcholine concentration was characterized by an apparent dissociation constant of about 15 microM and a Hill coefficient of 1. The kinetics of the development of susceptibility to photolabeling and the apparent lack of positive cooperativity in the effect of acetylcholine on this development suggest that the preferentially photolabeled state is a transient, rapidly developing, desensitized state, rather than an open-channel state.

Affinity Labels↗
PubMed1977

[Synthesis and properties of carrier-fixed enzymes. VII. Linking of glucoamylase to dialdehyde cellulose, carboxymethylcellulose hydrazide and carboxymethylcellulose azide].

Glucoamylase (alpha-1,4-glucan glucohydrolase, EC 3.2.1.3) has been covalently linked to dialdehyde cellulose resulting in an immobilized enzyme containing 0.98% protein and an activity of 4.5 mg of the native enzyme per g of matrix, i.e. 46% relative activity. The complex lost its activity in continuous and batch hydrolysis of starch at 55 degrees C down to a limit of 18% of its original value. In contrast, the activity of the complex did not change when working at a temperature of 25 degrees C. Glucoamylase-carboxymethylcellulose complexes synthesized via carboxymethylcellulose hydrazide and azide, in contrast to MAEDA und SUZUKI [1], showed only an activity of 1 mg of the native enzyme per g of matrix. We did not succeed in coupling periodate-oxidized glucoamylase to carboxymethylcellulose hydrazide because the enzyme used lost nearly all of its activity already during periodate oxidation.

Azides↗
PubMed1988

Photoaffinity labeling of human placental monoamine oxidase-A by 4-fluoro-3-nitrophenyl azide.

Our previous work has shown that low concentrations of 4-fluoro-3-nitrophenyl azide (FNPA) (0.01-1 microM) photodependently inhibited only the type B monoamine oxidase in rat brain [Biochem. Pharmacol. 34:781-785 (1985)]. Evidence is presented in this paper indicating that higher concentrations of FNPA (15 microM) photodependently inhibit type A monoamine oxidase (MAO-A) from human placenta. FNPA acted as a competitive inhibitor for human placental MAO-A in the dark (Ki = 10 microM) when [14C]serotonin was used as the substrate. The inhibition of MAO-A activity by FNPA was concentration dependent and also irradiation time dependent. The specificity of the photodependent incorporation of FNPA to MAO-A was shown by the protective effect of serotonin during the irradiation. The kinetic analysis showed that the Vmax was decreased whereas the Km was not changed after FNPA was photolyzed with MAO-A. Furthermore, there was no recovery of MAO-A activity upon washing of the photolyzed FNPA-enzyme mixture. These results suggest that FNPA may be covalently bound to the substrate-binding site. Thus, under the present experimental conditions, FNPA is a suitable photoaffinity labeling probe for human placental MAO-A. This is the first photoaffinity label for MAO-A, which may be useful for characterizing the substrate-binding site of this enzyme.

Affinity Labels↗
PubMed1987

Stability constants of haemoglobin cyanide and azide measured by two-wavelength spectrophotometric method.

A two-wavelength spectrophotometric procedure for the simultaneous determination of haemoglobin and haemoglobin cyanide (HiCN) (or of haemoglobin and haemoglobin azide (HiN3)) concentrations in mixtures has been developed and applied to the determination of the stability constants of HiCN and HiN3. The analytically reliable procedure allowed stability constants to be estimated with about 10% (relative standard deviation, coefficient of variation) uncertainty. Values of 1.9 X 10(6) and 2.0 X 10(5) 1 X mol-1 were obtained for HiCN and HiN3, respectively. These results are discussed in relation to the optimal composition of the reagents for blood haemoglobin assay by the two methods.

Azides↗
PubMed1987

Membrane penetration of bovine factor V and Va detected by labeling with 5-iodonaphthalene-1-azide.

The membrane-binding properties of Factor V and Factor Va were investigated using the lipophyllic, photoactivable probe 5-[125I]iodonaphthalene-1-azide. In the presence of vesicles composed of 75% phosphatidylcholine and 25% phosphatidylserine, both Factor V and Va were found to be labeled by the probe. The label was almost exclusively localized to the carboxyl-terminal-derived component E of Factor Va. The results are consistent with the interpretation that component E is the membrane binding subunit of Factor Va and that the interaction between Factor V or Factor Va and the membrane involves the penetration of the protein into the lipid bilayer.

Affinity Labels↗
PubMedDate not supplied

[Thioamine compound content in urine determined by using an iodine-azide reagent and selenious acid reaction].

Iodine-azide reagent enabled to evaluate quantitatively content of thioamines excreted within a day. Concentration of thioketons in urine of patients was 11-15 microgram/eqv of thiourea per 1 ml, at the same time their excretion within a day accounted for 13.06 +/- 0.56 mg/eqv in women and 22.11 +/- 1.1 mg/eqv in men. Neither concentration of thioketones in urine nor their excretion in patients with various tumors studied were distinct from these patterns in urine of non-oncologic patients. Comparison of these two methods suggests that development of color on addition of selenous acid to urine is not due to reaction with thioamines present but to interaction with other unknown substances.

Amides↗
PubMed1976

Properties of the guanylate cyclase-guanosine 3':5'-monophosphate system of rat renal cortex. Activation of guanylate cyclase and calcium-independent modulation of tissue guanosine 3':5'-monophosphate by sodium azide.

The effects of sodium azide on guanylate cyclase activity of homogenates of rat renal cortex and on the guanosine 3':5'-monophosphate (cGMP) content of cortical slices were examined and compared to those of carbamylcholine and NaF. In complete Krebs-Ringer bicarbonate buffer containing 10 mM theophylline, tissue cGMP content was increased 5- to 6-fold by 0.05 mM carbamylcholine or 10 mM NaN3, and 3-fold by 10 mM NaF. Increases in cGMP were maximal in response to these concentrations of the agonists and occurred within 2 min. Exclusion of Ca2+ from the incubation media reduced basal cGMP by 50% in 20 min and abolished responses to carbamylcholine and NaF, while exclusion of Mg2+ was without effect. Analogous reductions in cGMP were observed in complete buffer containing 1 mM tetracaine, an agent which blocks movement of Ca2+ across and binding to biologic membranes. By contrast, exclusion of Ca2+ or addition of tetracaine did not alter relative cGMP responses to NaN3 (6-fold increase over basal), although levels were reduced in slices exposed to these buffers for 20 min. When slices were incubated without Ca2+ or with tetracaine for only 2 min prior to addition of agonists, basal cGMP did not decline. Under these conditions, both absolute and relative increases in cGMP in response to NaN3 were comparable to those of slices incubated throughout in complete buffer, while carbamylcholine and NaF effects on cGMP were abolished. NaN3 increased guanylate cyclase activity of whole homogenates (10- to 20-fold), and of the 100,000 X g soluble (20-fold) and particulate (4-fold) fractions of cortex. Prior incubation of slices with NaN3 in the presence or absence of Ca2+ or with Ca2+ plus tetracaine also markedly enhanced enzyme activity in homogenates and subcellular fractions subsequently prepared from these slices. In the presence of 3 mM excess MnCl2, NaN3 raised the apparent Km for MnGTP of soluble guanylate cyclase from 0.11 mM to 0.20 mM, and reduced enzyme dependence on Mn2+. Thus, when Mg2+ was employed as the sole divalent cation in the enzyme reaction mixture basal and NaN3-responsive activities were 7% and 30% of those seen with optimal concentrations of Mn2+, respectively. Under a variety of assay conditions where responses to NaN3 were readily detectable, alterations in guanylate cyclase activities could not be demonstrated in response to carbamylcholine or NaF. By contrast Ca2+ increased the guanylate cyclase activity 6- to 7-fold over basal under conditions of reduced Mn2+ (0.75 mM Mn2+/1 mM GTP). This latter effect of Ca2+ was shared by Mg2+ and not blocked by tetracaine. Carbamylcholine, NaF, Ca2+, and NaN3 all failed to alter cGMP phosphodiesterase activity in cortex. Thus, while carbamylcholine and NaF enhance renal cortical cGMP accumulation through actions which are dependent upon the presence of extracellular Ca2+, NaN3 stimulates cGMP generation in this tissue through an apparently distinct Ca2+-independent mechanism.

Animals↗