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PubMed1995

Influence of salinity on copper and azide toxicity to larval topsmelt Atherinops affinis (Ayres).

Performance of a 7-d growth and survival toxicity test protocol using larval topsmelt, Atherinops affinis (Ayres), was evaluated for copper chloride and sodium azide at representative estuarine salinities. Results showed that topsmelt are amenable to toxicity testing at estuarine salinities ranging from 5 to 34/1000 since control survival was 100% in all toxicity tests. Sensitivity to both toxicants increased at lower salinities, with the LC50s for copper ranging from 205 micrograms/L at 34/1000 to 44 micrograms/L at 10/1000, and those for sodium azide ranging from 54 mg/L at 34/1000 to 7 mg/L at 5/1000. Larval tissue osmolality decreased with increasing copper concentration relative to control fish. Copper uptake was not affected by changes in salinity. This suggests that increased sensitivity to copper was due, in part, to the increasing physiological challenge of osmoregulation. It is also possible that cupric ion concentration increased at lower salinities, resulting in reduced larval survival. It is hypothesized that increased sensitivity to azide at lower salinity was due to the interaction between azide toxicity and increasing osmotic challenge. A second experiment with azide showed that larval acclimation time did not affect the interaction between salinity and azide toxicity.

Analysis of Variance↗

PubMed1977

Innocuity and toxicity testing of non-viral components of foot-and-mouth disease vaccines.

Some biological properties of 3 different adjuvants: saponin, DEAE-dextran and sodium azide applied in foot-and-mouth vaccines have been studied. As tested in guinea pigs, by dialysis of various batches of saponin, the author succeeded in reducing their toxicity by 80 to 90%, their hemolytic activity by 60 to 75% and their inflammatory capacity by 40 to 50%, whereas in cattle the inflammatory capacity of dialyzed saponin batches decreased by 80 to 90%. The inflammatory capacity of DEAE-dextran is about 50 to 60% less than that of the saponin. The effect of saponin and sodium azide has directly been studied in virus suspension also. Neither the saponin nor the sodium azide affected adversely the infectivity and immunogenicity of the antigen. The loss of potency due to the storage of the vaccine is not in relationship with the presence of the two above-named components.

Adjuvants, Immunologic↗

PubMed1996

Assessment of aspects of the toxicity of Clostridium perfringens epsilon-toxin using the MDCK cell line.

1. The epithelial Madin Darby Canine Kidney (MDCK) cell line was used to study the toxicity of epsilon-toxin from Clostridium perfringens. The epithelial MDCK cell line is known to be sensitive to epsilon-toxin of Clostridium perfrigens and to investigate its mechanism of action, the neutral red assay has been used to dermine the viability of cultures of this cell line. 2. Comparison of the LC50s obtained at 34 degrees C and 0 degree C showed that the lethality of epsilon-toxin was reduced by 18-fold at the lower temperature. The effect of temperature on epsilon-toxin lethality is unlikely to be due to reductions in membrane fluidity for the addition of Ca2+ or Mg2+ (2 mM) to buffer containing toxin was without effect. Varying the pH of the toxin-containing buffer from 6.9 to 8.7 did not increase the lethality of the toxin, though the most acidic pH used (5.8) was found to potentiate its action on MDCK cells. 3. The effect of inhibiting endocytosis on the lethality of epsilon-toxin was also investigated by incubating cultures of MDCK cells with and without sodium azide over a range of concentrations of toxin. The co-administration of sodium azide did not reduce the toxicity of epsilon-toxin, suggesting that energy-dependent uptake processes such as endocytosis were unlikely to be involved in its mechanism of action. The results are, however, consistent with known receptor-based mechanisms of uptake and with other mechanisms of internalisation across the plasma membrane. epsilon-toxin thus interacts with cell surfaces by a temperature sensitive mechanism potentiated by low pH.

Animals↗

PubMed2001

Extrusion of fluorescein diacetate by multidrug-resistant Candida albicans.

Over-expression of multidrug efflux transporters causes Candida albicans cells to be resistant to azole antifungal agents. There are several kinds of indicator for multidrug resistance (MDR) phenotype of higher eukaryotic cells. Calcein AM is a prefluorochrome that is known as a substrate for multidrug efflux transporters of mammalian cells. We investigated whether calcein AM was also extruded by the ATP-dependent multidrug transporter (cdr1p) of C. albicans. There was no significant difference in the accumulation of calcein AM between MDR cells and drug-susceptible cells of C. albicans even with sodium azide, suggesting that calcein AM may not be associated with the CDR1-gene-related multidrug efflux system of C. albicans. However, a structurally related prefluorochrome derivative, fluorescein diacetate (FDA), was shown to be extruded by the CDR1 mRNA-overexpressing yeast cells. In comparison with drug-susceptible cells, the resistant cells emitted very weak fluorescence when stained with FDA. Furthermore sodium azide increased the fluorescence of the resistant cells more than 20 times, whereas the fluorescence in the drug-susceptible cells with FDA and sodium azide was three to four times stronger. These results suggested that FDA might be extruded by the CDR1-related multidrug efflux transporter of C. albicans.

Antifungal Agents↗

PubMed1986

Influence of skin source, penetration cell fluid, and partition coefficient on in vitro skin penetration.

Using split-thickness pig skin mounted on in vitro skin penetration-evaporation cells, standard conditions were developed to preserve the viability of the skin as judged by its ability to successfully graft to nude mice. The effects of variations from these conditions on the disposition of radioactivity of radiolabeled compounds were determined. No differences in percutaneous penetration were found for N,N-diethyl-m-toluamide, parathion, and progesterone when Tyrode's solution was used in place of tissue culture media. The percutaneous penetration of benzo(a)pyrene on human and pig skin was unaffected by the presence of sodium azide in the tissue culture media; however, with mouse skin, penetration was lower when sodium azide was present. The disposition of radioactivity following topical application of five radiolabeled compounds was similar on fresh skin compared with skin that had been frozen and exposed to ethylene oxide, although variability of the values was greater with the treated skin. The percutaneous penetration of several compounds was determined on skin with and without the epidermis. The penetration of compounds with a lower log P (log octanol-water partition coefficient) increased to a greater extent (e.g., benzoic acid, log P = 2, sixfold increase) than compounds with a higher log P (e.g., DDT, log P = 5, twofold increase). To further validate the use of pig skin, the percutaneous penetration of 11 compounds on pig skin were correlated (r = 0.79) with the values obtained for human skin under standardized in vitro conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2002

Effect of storage on some volatile aroma compounds in fresh-cut cantaloupe melon.

Changes in volatile aroma constituents of fresh-cut cantaloupe melon with storage were determined by headspace solid-phase microextraction gas chromatography-mass spectrometry. The compounds isolated from the fruit immediately after cutting were predominantly aliphatic and aromatic esters. Storage of fruit at 4 degrees C caused a considerable decrease in concentration of esters and synthesis of the terpenoid compounds beta-ionone and geranylacetone over a period of 24 h. This change in the volatile profile with storage is consistent with that of a stress-induced defense response in the cut fruit as an adaptation process to tissue exposure and cell disruption. The same effect occurred in fruit stored at 22 degrees C and in those treated with sodium azide and ascorbic acid prior to storage. Fruit treated with ascorbic acid and sodium azide had higher concentrations of beta-ionone and geranylacetone and retained these compounds better with storage time. The reduction of esters appears to be an important early reaction step in the loss of freshness during storage of fresh-cut cantaloupe.

Ascorbic Acid↗

PubMed1993

Antimutagenic effects of casein and its digestion products.

The antimutagenic potential of casein was investigated using several mutagens, including some food-related mutagens, and the Salmonella/microsome and Escherichia coli DNA-repair tests. The effect depended on the type of mutagen and the incubation time of casein with the mutagens. Casein was very effective against benzo[a]pyrene, N-methylnitrosourea and nitrosated 4-chloroindole, and was less effective towards sodium azide and N-nitroquinoline-1-oxide (NQO). Preincubation increased the antimutagenic potential of casein towards NQO. Heating of casein (up to 20 min at 130 degrees C) did not alter its antimutagenic capacity. The effect of pepsin hydrolysis under simulated gastric conditions on the antimutagenic capacity of casein was tested with sodium azide and NQO in the Salmonella/microsome test. The peptides formed were separated by ultrafiltration or by isoelectric precipitation of casein, and were characterized by HPLC size-exclusion and Kjeldahl analysis. The antimutagenic potential of casein increased with pepsin hydrolysis; this increase was due to the peptides formed and might be explained by a better accessibility of casein peptides for interaction with mutagens. The antimutagenic potential of pepsin-hydrolysed casein towards sodium azide was observed over the whole dose-response curve.

Antimutagenic Agents↗

PubMed1998

Photostability and thermal stability of indocyanine green.

The photo-fading of the S0-S1 absorption band of the infrared dye indocyanine green sodium iodide (ICG-NaI) has been studied by cw laser excitation to the S1 band. Monomeric solutions in water, heavy water, aqueous sodium azide, human plasma, methanol and dimethyl sulfoxide (DMSO) as well as J-aggregated solutions in H2O and D2O have been investigated. A leucoform of indocyanine green seems to be formed by photodegradation. The degradation slows down with exposure time. The initial degradation yield, phi D,0, is determined. In monomeric and dimeric water, heavy water and sodium azide solutions the initial photostability is of the order of phi D.0 approximately 10(-3), in the organic solvents methanol and DMSO it is of the order of phi D.0 approximately 10(-5), and in human plasma it is phi D.0 approximately 2 x 10(-6). J-aggregates at high concentration are very stable. The thermal stability of the ICG-NaI solutions at room temperature in the dark is compared with their photostability. The thermal degradation time of monomeric and dimeric ICG-NaI in water, heavy water and sodium azide solutions is t(th) approximately 10 days, while no thermal degradation is observed for ICG-NaI J-aggregates and ICG-NaI in methanol, DMSO and human plasma.

Coloring Agents↗

PubMed1983

Hidden receptors for nerve growth factor in PC12 cells.

The binding of nerve growth factor (NGF) to its receptors in PC12 cells was studied in two experimental conditions: (a) cell fixation with paraformaldehyde followed by permeabilization of the plasma membrane with methanol and (b) metabolic poisoning of living cells with sodium azide. Paraformaldehyde fixation of PC12 cells causes a 60-70% reduction of NGF binding capacity; the original binding capacity is restored following permeabilization with methanol. A kinetic analysis of NGF binding under these conditions reveals a single homogeneous population of receptors at variance with experiments performed in living cells where two kinetically distinct types of NGF receptors were demonstrated [Landreth, G. E. and Shooter, E. M. (1980) Proc. Natl Acad. Sci. USA, 77, 4751-4755; Schechter, A. L. and Bothwell, M. A. (1981) Cell, 24, 867-874]. Our results suggest that a proportion of the NGF receptors in PC12 cells is hidden, i.e. not available for binding to the ligand, and in a dynamic equilibrium with exposed receptors. The existence of hidden receptors is confirmed by treatment of PC12 cells with sodium azide, which causes a 50% reduction in NGF binding capacity and protection from trypsin digestion of the remaining pool of hidden receptors. The latter become exposed at the cell surface following removal of sodium azide. Our data provide an interpretation for the as yet unsatisfactorily explained data on NGF receptors.

Cell Line↗

PubMed1989

Micro-scission of YAC tumor cells during antibody-dependent cellular cytotoxicity mediated by human neutrophils.

The cellular events accompanying neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) directed against YAC erythroleukemic target cells have been studied by time-lapse fluorescence-intensified microscopy. The YAC plasma membrane and cytosol were labeled with the fluorescent probes diC18Icc and eosin Y, respectively. Fluorescently labeled and IgG-opsonized YAC cells were incubated at 37 degrees C while observed by optical microscopy. During temporal studies of neutrophil-YAC conjugates, the cytosol of YAC cells accumulated in tubular and spherical compartments of the neutrophils' vacuolar apparatuses. To distinguish between several possible mechanisms of target cytosol uptake, diC18Icc-labeled YAC cells were observed during identical conditions. The membrane label diC18Icc was found to accumulate within neutrophils in an identical fashion. At roughly 30 min, 25 and 38% of neutrophils in apparent conjugates had internalized tumor cell cytosol or plasma membrane, respectively, within a vesicular compartment. The IgG-dependent uptake of eosin Y and diC18Icc by neutrophils was diminished by exposure to 2.5 mM sodium azide. When cells were exposed to 5.5 mM sodium azide, 1 mM iodoacetamide, or 4 degrees C, conjugate formation and uptake of eosin Y or diC18Icc were abolished. An artifactual accumulation of eosin Y or diC18Icc in neutrophils was further ruled out by control studies. Non-specific exchanges of eosin Y and diC18Icc labels of YAC cells with tannic acid-treated red blood cells (RBCs) and normal neutrophils were studied. Since hemoglobin binds tightly to eosin Y, RBCs can easily detect eosin Y leakage. No exchange of eosin Y or diC18Icc from YAC cells into bound tannic acid-treated erythrocytes was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody-Dependent Cell Cytotoxicity↗

PubMed2001

Application of the nitroblue tetrazolium-reduction method for studies on the production of reactive oxygen species in insect haemocytes.

The in vitro generation of reactive oxygen species (ROS) in haemocytes of Galleria mellonella, Aporia crataegi, Dendrolimus sibiricus, Aglais urticae (Lepidoptera) and Gryllus bimaculatus (Orthoptera), was studied by the method of nitroblue tetrazolium (NBT) reduction. Formazan formation (product of NBT reduction) was observed in haemocytes of all the insects examined, except A. urticae. Lypopolysaccharide and zymosan reduced the number of NBT-positive cells after 1 h incubation and an increase was registered after 4 h incubation. The inhibitors of the respiratory chain enzyme (sodium azide) and melanogenesis (phenylthiourea) reduced formazan formation in nonactivated insect blood cells. No influence of sodium azide and phenylthiourea was found on the activated haemocytes. The results suggest that the generation of ROS in insect haemocytes occured as a result of processes such as respiration and melanization during phagocytosis and encapsulation.

Animals↗

PubMed1981

[The presence of an albino ERG in the pigmented rat: genetic implications (author's transl)].

UNLABELLED: The electroretinogram (ERG) of the albino rat (genotype c/c) differs from that of the pigmented rat (hooded, Long-Evans) by the attenuation of the b-wave and the disappearance of the c-wave which is replaced by a negative component. The present study has shown that a similar alteration in the ERG is present in the hypodactyl hooded rat (genotype hd/hd) (Fig. 1). The comparative analysis of the recordings indicated that: 1. The detection thresholds for the a and b waves were identical in the three varieties (Fig. 2). 2. The wave-form of the P III component observed after ischemia was also identical in the three strains (Fig. 1). 3. The modifications in the ERG induced by sodium azide (Fig. 4) and sodium iodate (Fig. 5) in the hd/hd rat are the same as those which have been reported in the c/c strain, and (as in the latter case) the absence of the c-wave is not due to the disappearance of P I, but rather to an attenuation of this component resulting in a negative algebraic sums of P I and P III (Fig. 6). 4. IN CONCLUSION: the alterations in the ERG recording, observed in albinos, were interpreted as being due to some fragility in the photoreceptors, consequent to a lack of pigmentary protection. Such an interpretation is invalidated by the fact that a similar ERG pattern was found in both pigmented and albino rats. Because genetic deficiencies other that the absence of a chromogene factor can modify the ERG, it is suggested that the c-gene, as is the case for the hd-gene, could be responsible for a disturbance of foetal erythropoiesis. Thus, the resulting circulatory problems, without provoking any visible structural effects, would nevertheless affect retinal functioning.

Albinism↗

PubMed1982

Monocyte-mediated damage to Rhizopus oryzae hyphae in vitro.

Clinicopathological correlations from human cases and experimental animal studies suggest that neutrophils are critical components of the host response to mucormycosis but that other cellular defense mechanisms appear to be important as well. Since our previous studies demonstrated that Rhizopus oryzae hyphae which are too large to be ingested completely can be damaged and probably killed by human neutrophils, we studied the antihyphal activity of human monocytes. As with neutrophils, light and electron microscopic studies indicated that monocytes attached to hyphae and appeared to destroy them in the absence of serum. As judged by our previously described assay for the leukocyte-induced inhibition of [14C]uracil uptake by hyphae, quantitative damage to hyphae by monocytes was 40.8 +/- 2.2% in 54 experiments. Neither attachment to nor damage of hyphae by monocytes was augmented by the presence of 10% human serum. As with neutrophils, monocyte-mediated damage of R. oryzae was significantly decreased by some inhibitors of oxidative metabolism and scavengers of the potentially microbicidal oxidative leukocyte products, which included 10(-4)M sodium azide, 10 (-3) M sodium cyanide, catalase, 10(-3) M histidine, 10(-3) M tryptophan, and 10(-4) M 1,4-diazobicyclo[2.2.2]octane but not superoxide dismutase, 1.4 X 10(-2) M dimethyl sulfoxide, and 4.0 X 10(-1) M mannitol. Moreover, monocytes from three patients with chronic granulomatous disease failed to damage hyphae at all. In contrast to our previous data for neutrophils, polyanions (10(-5) M polyaspartic or polyglutamic acid) did not inhibit monocyte-mediated hyphal damage. Thus, monocytes can damage and probably kill R. oryzae hyphae by oxidative mechanisms and so may be involved in host defense mechanisms against mucormycosis.

Azides↗

PubMed1958

Effects of potassium, sodium, and azide on the ionic movements that accompany activity in frog nerves.

Stimulation of intact or desheathed frog sciatic nerves produced an increase in the sodium content and a decrease in the potassium content of this tissue. In desheathed preparations the magnitudes of the changes in ionic contents decreased as the concentration of the potassium in the bathing solution was increased, while changing the external sodium concentration produced small effects on the ionic shifts. During tetanization, the rate of decline of the compound action potential also decreased as the external potassium concentration increased. Eliminating the activity respiration with 0.2 mM azide did not greatly modify the changes in sodium and potassium distribution that accompanied activity in either intact or desheathed nerves.

Action Potentials↗

PubMed2001

Enhancement of oxidative damage to cultured cells and Caenorhabditis elegans by mitochondrial electron transport inhibitors.

The mechanisms that lead to mitochondrial damage under oxidative stress conditions were examined in primary and cultured cells as well as in the nematode Caenorhabditis elegans (C. elegans) treated simultaneously with electron transport inhibitors and oxygen gas. Oxygen loading enhanced the damage of PC 12 cells by thenoyltrifluoroacetone (TTFA, a complex II inhibitor), but did not by rotenone (a complex I inhibitor), antimycin (a complex III inhibitor), and sodium azide (a complex IV inhibitor). In primary hepatocytes, the enhancement was observed with the addition of sodium azide and rotenone, but not by TTFA or antimycin. In the nematode, only rotenone and TTFA enhanced the sensitivity under hyperoxia. These results demonstrate that highly specific inhibitors of electron transport can induce oxygen hypersensitivity in cell levels such as PC 12 cells and primary hepatocytes, and animal level of C. elegans. In addition the cell damage is different dependent on cell type and organism.

Animals↗

PubMed1987

B-cells purified using azide give different responses in vitro to B-cells purified without azide.

Some established techniques for B-cell enrichment include azide in the media. Here, B-cells were enriched using a technique which transiently exposed the cells of 15 mM sodium azide. After 3-4 days in culture, the precursor frequency of autoantibody-secreting cells in this population was 0.113%. In contrast, when B-cells were enriched using a technique which eliminated their exposure to sodium azide, the number of autoantibody-secreting precursor cells detected in cultures was increased up to 20-fold. Therefore, it is concluded that transient exposure to azide affects functional activities of B-cells in vitro.

Animals↗

PubMed1984

Comparison of a forward and a reverse mutation assay in Salmonella typhimurium measuring L-arabinose resistance and histidine prototrophy.

A forward and a reverse mutation assay designed to detect environmental mutagens have been compared in Salmonella typhimurium. The forward mutation assay scored resistance to L-arabinose and the reverse assay, reversion of histidine auxotrophy. Eighteen chemicals of different structural groups, all known to be mutagenic in the histidine reverse assay, were applied to strains carrying the genetic markers needed to perform both mutation assays. The mutagenicity of each chemical was determined by both plate and liquid tests. The plate test counted absolute numbers of surviving mutants and the liquid test separately measured survival and frequency of mutants among the survivors. All the chemicals used were found to be mutagenic in both mutation assays. The response of the L-arabinose assay was equal to or larger than the response of the histidine assay in the case of 16 chemicals. The two other compounds, 2-nitrofluorene and sodium azide, were detected more efficiently by the histidine assay. Sodium azide, a non-carcinogenic compound, is a potent mutagen in the histidine assay, but very weak in the L-arabinose assay.

Arabinose↗

PubMed1995

Singlet oxygen generation in the superoxide reaction.

ESR spin trapping was utilized to study the singlet oxygen (1O2) generation in the reaction of superoxide (O2) with H2O2. The spin trap used was 2,2,6,6-tetramethyl-4-piperdone. Incubation of xanthine, xanthine oxidase and H2O2 generated 1O2 spin adduct signal. Omission of xanthine, xanthine oxidase or H2O2 caused a sharp decrease in 1O2 generation. 1O2 scavenger, sodium azide, inhibited 1O2 generation while .OH scavenger, ethanol, only slightly decreased the signal intensity. Potassium superoxide (KO2) decomposition generated 1O2. Catalase and sodium azide inhibited 1O2 generation and H2O2 enhanced it. The results demonstrate that O2 is capable of generating 1O2 upon reaction with H2O2.

Azides↗