New naphthalene whole-cell bioreporter for measuring and assessing naphthalene in polycyclic aromatic hydrocarbons contaminated site.

A new naphthalene bioreporter was designed and constructed in this work. A new vector, pWH1274_Nah, was constructed by the Gibson isothermal assembly fused with a 9 kb naphthalene-degrading gene nahAD (nahAa nahAb nahAc nahAd nahB nahF nahC nahQ nahE nahD) and cloned into Acinetobacter ADPWH_lux as the host, capable of responding to salicylate (the central metabolite of naphthalene). The ADPWH_Nah bioreporter could effectively metabolize naphthalene and evaluate the naphthalene in natural water and soil samples. This whole-cell bioreporter did not respond to other polycyclic aromatic hydrocarbons (PAHs; pyrene, anthracene, and phenanthrene) and demonstrated a positive response in the presence of 0.01 µM naphthalene, showing high specificity and sensitivity. The bioluminescent response was quantitatively measured after a 4 h exposure to naphthalene, and the model simulation further proved the naphthalene metabolism dynamics and the salicylate-activation mechanisms. The ADPWH_Nah bioreporter also achieved a rapid evaluation of the naphthalene in the PAH-contaminated site after chemical spill accidents, showing high consistency with chemical analysis. The engineered Acinetobacter variant had significant advantages in rapid naphthalene detection in the laboratory and potential in situ detection. The state-of-the-art concept of cloning PAHs-degrading pathway in salicylate bioreporter hosts led to the construction and assembly of high-throughput PAH bioreporter array, capable of crude oil contamination assessment and risk management.

Can high-performance liquid chromatography coupled with fluorescence detection under all conditions be regarded as a sufficiently conclusive confirmatory method for B-group substances?

Commission Decision 2002/657/EC requires confirmatory analysis of B-group compounds when detected at levels above the permitted limit. In contrast to banned substances, for B-group substances, the use of mass spectrometric techniques is not obligatory and several techniques including liquid chromatography (LC)-ultraviolet light (UV) on two different LC columns and (single-column) high-performance liquid chromatography (HPLC)-fluorescence (Flu) are considered to deliver sufficient evidence for the identification of the detected substance. The analysis of sodium salicylate in animal drinking water collected at poultry farms is presented here as an example to show that even in a simple matrix such as animal drinking water, fluorescence detection in some cases may provide inadequate specificity. Of 50 samples analysed by LC-Flu, 18 tested positive for sodium salicylate. However, only in one sample was the presence of the analyte confirmed with mass spectrometric detection; the others were blank. Consequently, the LC-Flu results obtained were false-non-compliant for sodium salicylate. A second case concerning the analysis of avermectins in milk by HLPC-Flu is briefly described. For a number of samples analysed in the framework of a proficiency test, false non-compliant results for emamectin were reported due to a background interference sometimes present that practically co-eluted with the analyte. The observed retention time difference (1%) was well below the criterion (2.5%) specified in Commission Decision 2002/657/EC. Considering the impact of positive findings on individual farmers as well as on trade, product image and food safety perception by the consumer, it is concluded that also for B-group substances false-non-compliant results should be avoided whenever possible. This is especially important when the results are treated as and are expected to have the same repercussions as in the case of banned A-group substances. In these circumstances, only results obtained by mass spectrometry should be considered for confirmatory purposes.

Shear banding fluctuations and nematic order in wormlike micelles.

Using rapid NMR velocimetry we demonstrate the existence of shear band fluctuations in the Couette flow of the wormlike micelle system, 10% w/v cetylpyridinium chloride and sodium salicylate (molar ratio 2:1) in 0.5 M 2H2O NaCl brine. We show that the fluctuations may be either quasirandom or periodic, the fluctuation spectrum being similar to that observed in the stress. Despite the equilibrium fluid being far from an isotropic-nematic transition, deuterium NMR shows that the onset of shear banding is associated with a nematic micellar state whose order parameter depends on shear rate.

The effect of hydrotropic agents on the heat coagulation of bovine serum albumin.

The effect of two hydrotrophic solubilizers on the heat coagulation of bovine serum albumin (BSA) has been investigated. Photon correlation spectroscopy indicated possible unfolding of BSA molecules in solutions of sodium benzoate and sodium salicylate at 25 degrees C. The effect of these hydrotropes on the heat coagulation of BSA was concentration-dependent. Relatively low concentrations stabilized the protein structure as indicated by the increase in the transition temperature(Tm) and induced gelation at temperatures and BSA concentrations lower than those required in the absence of hydrotropes. Higher concentrations of the hydrotropes considerably reduced Tm and inhibited gelation of BSA, the effect of sodium salicylate being more pronounced, as was the lower aggregation rate of BSA. The behaviour of these hydrotropes as protein denaturants differs from that of neutral electrolytes but is similar to that of concentrated solutions of urea.

Solute release from a porous polymeric matrix: inwardly tapered disk with a central releasing hole.

Diffusional solute release from an inert porous polymeric matrix was evaluated using sodium salicylate released from fused, inwardly tapered, polyethylene disk matrices (1.27 cm in diameter) with a central releasing hole. Two types of matrix were made by compressing (175 MPa) a sodium salicylate-melt polyethylene mixture with two different sets of circular conical punches having angles of 20 degrees and 30 degrees, with an axis perpendicular to the cone. The matrix sodium salicylate loading was greater than its solubility limit in the release medium. The fused matrices were coated with wax and perforated in their center to create a surface available for solute release. Flat disks with a central cylindrical hole were also made to compare the release profiles. An approximate solution was developed for these inwardly tapered disks and tested against experimental results. The theoretical model and experimental results showed good agreement and indicated that this type of matrix geometry may be useful as a pharmaceutical dosage form to approximate zero-order release.

Prevention of molecular self-association by sodium salicylate: effect on insulin and 6-carboxyfluorescein.

The effect of sodium salicylate on the concentration-dependent self-association of insulin and 6-carboxyfluorescein (CF), as expressed by metachromasy, fluorescence, and changes in aqueous solubility, was learned. By decreasing the CF concentration from 12 to 0.48 microgram.ml-1, lambda max peaks shift from the shorter wavelengths (451, 474 nm), indicating the presence of oligomers, toward the monomer wavelength region (484 nm). Sodium salicylate shifts the peaks of a 12 micrograms.mL-1 CF solution towards the monomer region, eliminating the peak at the lower wavelengths and generating a spectrum with one peak at 490 nm, the effect being concentration dependent. The fluorescence of insulin and CF solutions increases with their concentration. Quenching of these solutions was observed, up to complete elimination of fluorescence, when various concentrations of salicylate were added. The water solubility of both molecules, CF and insulin, was considerably increased with the addition of increasing concentrations of salicylate to the solutions: at 37 degrees C, 2.5 M sodium salicylate solution increases the CF solubility 532 times from 12.2 to 6.5 mg.mL-1, and 1.5 M salicylate increases the solubility of insulin 7875 times, thus an aqueous solution containing 630 mg.mL-1 of insulin may be prepared. The results obtained here, together with our previously reported data, indicate that the interference between sodium salicylate and drug self-association behavior, by increasing drug solubility, may substantially contribute to the improved drug bioavailability mediated by salicylate.

Prevention of molecular self-association by sodium salicylate: effect on methylene blue.

Sodium salicylate improves the rectal absorption of drugs which exhibit molecular self-association; it is suggested that salicylate may improve drug bioavailability by altering the drug self-association pattern. Methylene blue was chosen as a model molecule for investigating the interference of salicylate with drugs undergoing self-association. The effect of sodium salicylate on the concentration-dependent association of methylene blue as expressed by metachromasy was observed and compared with the effects of other additives: urea, sodium chloride, sodium acetate, sodium sulfate, and sodium benzoate. By increasing the methylene blue concentration from 10(-5) M to 2 X 10(-3) M, the lambda max peak shifts from the longer wavelength region (approximately 660 nm) of the monomer toward the shorter (approximately 600 nm) indicating the presence of dimers and other oligomers. Addition of increased concentrations of sodium salicylate had a deaggregative effect on a 10(-3) M methylene blue solution, shifting the peaks toward the monomer region. On the other hand, the addition of 0.5 M of any of the following salts: sulfate, acetate, or chloride, to a 10(-3) M, aqueous solution of methylene blue had the opposite effect, eliminating the lambda max peak at 660 nm and generating a spectrum with one peak at approximately 600 nm, which indicated a high degree of self-association. The sodium salicylate effect is concentration dependent, with a high excess (approximately 450 times on a molar scale) being necessary to reduce the self-association. At lower concentrations of salicylate, precipitation occurs in the system.(ABSTRACT TRUNCATED AT 250 WORDS)

First-derivative spectroscopic determination of acetaminophen and sodium salicylate in tablets.

A first-derivative spectroscopic method for the simultaneous determination of acetaminophen and sodium salicylate in tablets was developed. Solutions of this drug combination in acidic ethanol were analyzed using their respective spectral responses at 258.5 and 317.0 nm. The method, which can be used for tablet composite assay and content uniformity analysis, is linear for acetaminophen concentrations ranging from 0.0 to 21.6 micrograms/mL, and for sodium salicylate concentrations ranging from 0.0 to 36.0 micrograms/mL. Relative standard deviations for the assay of both drugs in commercial tablets were less than 2%, and recoveries of acetaminophen and sodium salicylate from spiked samples were 99.7 and 100.1%, respectively. The results obtained by first-derivative spectroscopy were in agreement with the results of a liquid chromatographic procedure for acetaminophen and a fluorometric method for sodium salicylate. The technique used for the selection of wavelengths for analysis is also described.

Omission of pepsin from simulated gastric fluid in evaluating activated charcoals as antidotes.

Although simulated gastric fluid USP calls for 3.2 g of pepsin/liter, most researchers omit pepsin when evaluating adsorbents. The present results show that, although pepsin adsorbs strongly to activated charcoal, it does not interfere significantly with the adsorption of a typical drug like sodium salicylate. Therefore, its omission is justified. Gastric mucin also had almost no effect on salicylate adsorption.

The effect of sodium salicylate on bile secretion in the dog.

1. The I.V. injection of sodium salicylate (100 mg/kg) in the dog caused a rapid and maintained choleresis of the order of 300-600 percent of control levels. 2. The total amount of salicylate excreted in bile was only 1-2 percent of that injected. 3. The secretion of bile salt into bile was not increased by salicylate. 4. The choleresis caused by salicylate was associated iwth a decrease in the concentrations of sodium and of bile salt in bile, and with an increase in the concentration of chloride; the biliary concentration of bicarbonate was either temporarily increased or unchanged. 5. The choleresis could not be inhibited by the intra-portal injection of of ouabain (0-1 mg/kg). 6. The secretion of bromsulphthalein into bile was not potentiated by the choleresis. 7. The choleretic efficiency of sodium taurocholate was not increased in the presence of salicylate. 8. The injection of acetazolamide (20 mg/kg) in the presence of a salicylate choleresis, caused an increase in the osmolaity of bile and an increase in biliary sodium concentration, such that the composition of bile more nearly approached that of plasma. 9. The possible mechanisms underlying the choleretic effect of sodium salicylate are discussed.