Risk assessment uncertainties.
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Animals↗
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High fraction of penta-coordinated aluminium in amorphous and crystalline aluminium borates.
27Al and 11B magic-angle spinning nuclear magnetic resonance (MAS NMR) results are reported on aluminium borates of composition Al2(1 - x)B2xO3 (0 < or = x < or = 0.7). It is shown that starting from liquid precursors with hexa-coordinated Al and tri- and tetra-coordinated B, porous aluminium borates are obtained containing high fractions of penta-coordinated Al. The presence of boron in the crystalline phases stabilizes penta-coordinated Al, existing already in their amorphous precursors, and at the same time distorts the surroundings of the hexa-coordinated Al. The reversible effect of air exposure on low-coordinated Al (Al4C, Al5C) and B (B3C) proved that at least these species are situated at the surfaces of the pores. The A9B2 phase still contains a small fraction of tetra-coordinated B. The 27Al and 11B MAS NMR spectra of A9B2 show a well-resolved powder spectrum with no indication of broadening due to a distorted configuration.
Aluminum Compounds↗
Double rotation and magic-angle spinning nuclear magnetic resonance study of 27Al: reexamination of the aluminium borate 9Al2O3.2B2O3.
27Al nuclear magnetic resonance spectra of polycrystalline aluminium borate 9Al2O3.2B2O3 have been measured in double rotation at 11.7 and 7.0 T and high-speed magic-angle spinning at 7.0, 9.4, 11.7, 14.1 and 17.6 T. Spinning sidebands from the satellite transitions were observed at 7.0 and 14.1 T. Each of the four structural aluminium sites [Al(IV), Al(V)(1), Al(V)(2) and Al(VI)] are observed, characterised and assigned in the spectra. The obtained parameter set gives a fully consistent interpretation in agreement with the crystal structure of the compound.
Aluminum Compounds↗
Amperometric glucose biosensor with extended concentration range utilizing complexation effect of borate.
Borate buffer strongly decreases amperometric response of a glucose oxidase linked pO2 or H2O2 sensing electrode, extending substantially its linear calibration range. With increasing pH and concentration of the buffer the upper limit for glucose can be varied between 1 and 30 mmol l-1 glucose. The effect of borate ion is explained by the rapid complexation of glucose decreasing the equilibrium concentration of free beta-anomer, the specific substrate of glucose oxidase. The high loading of cross-linked enzyme inside the sensor membrane is necessary for the measurement to ensure an almost constant response factor (delta i per 1 mmol l-1) between pH 5 and 10. Analysis in stirred solution and in a flow-through system has been employed for the measurement of elevated glucose levels in heparinized human blood or plasma samples.
Biosensing Techniques↗
Separation of yeast phospholipids using one-dimensional thin-layer chromatography.
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Boric Acids↗
Analysis of oligonucleotide annealing by electrophoresis in agarose gels using sodium borate conductive medium.
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Boric Acids↗
ESR response to gamma-rays of alanine pellets containing B(OH)3 or Gd2O3.
ESR response to gamma-irradiation (1-50 Gy) of blends containing alanine and either B(OH)(3) or Gd(2)O(3) is reported. The sensitivity of the alanine--B(OH)(3) blend is comparable to the sensitivity of pure alanine, although its lowest detectable dose, LDD, is smaller ( approximately 1.3 Gy) than that of pure alanine ( approximately 2.9 Gy). Alanine with Gd(2)O(3) is about two times more sensitive than pure alanine, and its LDD is 0.8 Gy. The better sensitivity and LDD are probably due to the high atomic number (Z=64) of gadolinium, which enhances the interaction probability with photons and, consequently, the radical yield. This study suggests that other high-Z atoms may be useful for increasing the sensitivity of the response of alanine to gamma-radiation.
Alanine↗
A process to prepare a synthetic filter material containing nutrients for biofiltration.
In this study, an optimal process to prepare a synthetic filter material (poly(vinyl alcohol) (PVA)/peat/KNO(3) composite bead) containing nutrients was developed for biofiltration. The optimal preparing condition was that each of the peat and PVA aqueous solutions contains 6.4 g KNO(3) and the nitrogen content in the boric and phosphate aqueous solutions must retain higher than 3.94 and 1.52 g N/l, respectively. The equilibrium amount of water-soluble nitrogen dissolved out of the prepared composite bead was between 7.95 and 8.21mg N/g dry solid. The path of water-soluble nitrogen dissolving out of the A-type bead was the water-soluble nitrogen dispersed in the peat phase initially diffused into the outer PVA phase and then it diffused out of the bead surface. And the path of water-soluble nitrogen dissolving out of the H-type bead was the water-soluble nitrogen dispersed in both the peat and PVA phases simultaneously diffused into the outer PVA phase and out of the bead surface, respectively. The microbial growth rate k(g) of the H-type composite bead was higher than that of the A-type composite bead approximately 1.09-1.58 times, and its value was between 0.100 and 0.417 day(-1) as the composite bead was immersed in 0-0.896 M KNO(3) solution. The maximum value of k(g) appeared at the composite bead immersed in 0.384 M KNO(3) solution and was higher than that of the compost by a factor approximately 1.49. The percentage of removed volatile organic compounds (VOCs) remained at more than 98% during the biofilter operating 230 days as the composite bead was immersed in KNO(3) aqueous solution before packing. This composite bed was without the further addition of nutrients during this operating period. It was proved that this composite bead was superior to the compost as a filter material.
Air Pollutants↗
Selective determination of trimethylamine in air by liquid chromatography using solid phase extraction cartridges for sampling.
The selective determination of trimethylamine (TMA) in air by liquid chromatography is reported. Sampling is effected by flushing air through C18-packed solid-phase extraction (SPE) cartridges at a flow rate of 15 mL/min for 15 min. Next, TMA is desorbed from the cartridges and injected into the chromatographic system. The analyte is then selectively retained on a precolumn (20 mm x 2.1 mm i.d., packed with 30 microm, Hypersil C18 phase), and derivatized on-line by injecting 9-fluorenylmethyl chloroformate (FMOC). Finally, the TMA-FMOC derivative is transferred to the analytical column (125 mm x 4 mm i.d., LiChrospher 100 RP18, 5 microm), and monitored at 262 nm. The method was applied to the measurement of TMA in air in the 0.25-2.5 microg interval (equivalent to concentrations of TMA of 1.1-11 mg/m3), providing good linearity, reproducibility and accuracy. The mean recovery of TMA was (96 +/- 7%) (n = 12), and the limit of detection was 0.05 microg. The proposed procedure allows the selective determination of TMA in the presence of other primary and secondary short-chain aliphatic amines.
Air Pollutants, Occupational↗
Microemulsion electrokinetic chromatography for the separation of retinol, cholecalciferol, delta-tocopherol and alpha-tocopherol.
A microemulsion electrokinetic chromatographic method was used to separate fat-soluble vitamins. The separation of retinol, cholecalciferol, and delta- and alpha-tocopherol was performed using a microemulsion containing 0.75% (v/v) n-heptane, 30 mM bis(2-ethylhexyl)sodium sulfosuccinate (AOT), 5% (v/v) 1-butanol, 15% (v/v) 1-propanol and 15% (v/v) methanol in 20mM boric acid-sodium borate buffer. The effect of the different microemulsion constituents was studied, including the type and concentration of surfactant, buffer, oil and co-surfactants. The presence of methanol in the microemulsion was found to be necessary to achieve the separation of the tocopherols. Detection was carried out at 200, 265 and 325 nm for the tocopherols, cholecalciferol and retinol, respectively. Calibration curves and precision data were obtained for each analyte. Good linear relationships were found between the analytical signal and the analytes concentration in the 25-500 mg L(-1) for retinol and cholecalciferol, and 25-300 mg L(-1) for tocopherols ranges. The precision of the method afforded relative standard deviations in the 4.0-10% range.
Cholecalciferol↗
Regulation system for protease production in Vibrio vulnificus.
Vibrio vulnificus is a causative agent of serious food-borne diseases in humans related to consumption of raw seafoods. This human pathogen secretes a metalloprotease (VVP) that evokes enhancement of the vascular permeability and disruption of the capillaries. Production of microbial proteases is generally induced at early stationary phase of its growth. This cell density dependent regulation of VVP production in V. vulnificus known to be the quorum-sensing. When V. vulnificus was cultivated in Luria-Bertani (LB) medium, accumulation of the autoinducer, the signal molecule operating the quorum-sensing system, was detected. Moreover, expression of the vvp gene encoding VVP was found to be closely related with expression of the luxS gene that encode the synthase of the autoinducer precursor (luxS). These findings may indicate VVP production is controlled by the quorum-sensing system in LB medium. Furthermore, this system functioned more effectively at 26 degrees C than at 37 degrees C. When incubated at 37 degrees C in human serum supplemented with ferric chloride, production of VVP and expression of vvp increased in proportion to the concentration of ferric ion; whereas, expression of luxS was not increased. This suggests that VVP production in human serum containing ferric ion may be regulated mainly by the system other than the quorum-sensing system.
Bacterial Proteins↗
A simply and sensitive fluorometric method for determination of gentamicin in liposomal suspensions.
A new method for measuring gentamicin in liposomes fluorometrically is described. The assay is based on the reaction between the amino groups in the gentamicin molecule and o-phthaldialdehyde (OPA), under basic pH conditions; the product's fluorescence can be read directly on a simple fluorimeter. The effects of several factors (time of reaction, volume of the OPA reagent, and product stability) were investigated. The standard curve was linear in the concentration range of 0.5-4.0microg, showing an excellent determination coefficient of r(2)=0.99. Additionally, the influence of different liposomal lipids on gentamicin determination was tested. Liposomal lipids containing no free amino groups (PC, Chol, DOTAP) have no influence on the reaction when present in the reaction mixture. In contrast, amino groups containing lipid (SA) showed intense method interference. Therefore, a method of lipid extraction was adapted to remove undesired lipids. The described method was successfully utilised during 2 years of liposomal gentamicin experiments.
Anti-Bacterial Agents↗
Automated on-line SPE LC-MS/MS method to quantitate 6beta-hydroxycortisol and cortisol in human urine: use of the 6beta-hydroxycortisol to cortisol ratio as an indicator of CYP3A4 activity.
A sensitive method for quantitation of urinary 6beta-hydroxycortisol (6beta-HC) and cortisol using on-line SPE and LC-MS/MS was developed and validated. Human urine samples were injected directly onto an on-line solid phase extraction apparatus, Prospekt-2, followed by HPLC separation and electrospray triple quadrupole LC-MS/MS detection. The inter-day precision for the 6beta-HC:cortisol ratio was 7-9%. The lower limit of quantitation was 1 and 0.2 ng/mL for 6beta-HC and cortisol, respectively. Using the method we observed a diurnal variation on the 6beta-HC:cortisol ratio in healthy volunteers with the maximal ratio observed in the 2-10 pm urine collection period.
Autoanalysis↗
Explosive properties of 1-hydroxybenzotriazoles.
1-hydroxybenzotriazole and its derivatives are widely used as peptide coupling reagents. However, people are often not aware that such compounds show explosive properties when heated under defined confinement or when subjected to mechanical stimulus. 1-Hydroxybenzotriazole (HOBt) is able to propagate a detonation when a stronger booster is used. Sometimes explosive substances are desensitized to suppress their hazardous properties, yet depending on the amount and nature of desensitizer, the result is often not quite satisfactory. During the last years, some 1-hydroxybenzotriazoles were tested at BAM. The results are presented in this paper.
Borates↗
Separation of thiamin and its phosphate esters by capillary zone electrophoresis and its application to the analysis of water-soluble vitamins.
A capillary zone electrophoresis method for the separation and determination of thiamin and its phosphate esters (free thiamin, thiamin monophosphate, and thiamin pyrophosphate) was developed and optimized. The efficiency achieved with boric acid-sodium tetraborate decahydrate buffer (pH 8.24; 65-8 mM) at an applied potential of 30 kV gave the detection limit (S/N = 3) and the limit of quantitative measurement (S/N = 10) of thiamin and its phosphate esters ranging from 10(-4) to 6 x 10(-4) mM and from 6 x 10(-4) to 1.2 x 10(-3) mM, respectively. The effects of pH on separation and migration times of thiamin and its phosphate esters are described. The method was validated and applied to the quantitative determination of thiamin in commercial tablets containing both a massive and a normal dose of thiamin.
Electrophoresis, Capillary↗
FT-Raman spectroscopic evidences for the preferential solvation of sodium tetrafluorobrate in acetonitrile-based mixed solvents.
Solutions of sodium tetrafluorobrate in acetonitrile-dimethylformamide, and acetonitrile-dimethylsulfoxide mixtures have been studied by FT-Raman spectroscopy for three solvent compositions, respectively. New bands due to solvent molecules in the first solvation shell of Na(+) were detected in the region of the O=C--N deformation and CH(3) rocking mode for amide and of the S=O and C--S stretching modes for sulfoxide. The individual solvation numbers of sodium cation in different environment were deduced. In all the cases, it is found that the sodium ion was preferentially solvated by DMF or DMSO in respective binary solvents. This result was further supported by ab initio calculations.
Acetonitriles↗
The effect of intravenous magnesium hypophosphite in calcium borogluconate solution on the serum concentration of inorganic phosphorus in healthy cows.
The goal of this study was to determine the effect of intravenous (IV) administration of phosphite on the serum concentration of inorganic phosphorus in cows. Twelve clinically healthy cows were divided into four groups of three. All cows received 600 mL of a 40% calcium borogluconate solution; three cows each received this as a rapid (20 min) IV infusion with and without 6% magnesium hypophosphite, and three other cows each received this as a slow IV infusion (8 h) with and without 6% magnesium hypophosphite. Samples of blood were collected for the determination of serum concentrations of calcium, inorganic phosphorus and magnesium before and 10, 20, 40, 60 and 90 min and 2, 3, 4, 5, 6, 7, 8, 24, 48 and 72 h after the start of treatment. The concentration of calcium increased after treatment in all cows but the increase was most rapid in cows that received the rapid infusion. In cows that received the rapid IV infusion containing magnesium hypophosphite, the mean concentration of inorganic phosphorus decreased significantly 3-4 h after treatment compared with initial serum levels. The serum concentration of inorganic phosphorus did not change significantly in cows that received the rapid IV solution without magnesium hypophosphite or the slow IV infusion with or without magnesium hypophosphite. The serum concentration of magnesium increased after treatment in all cows receiving magnesium hypophosphite but remained unchanged in the others. The rapid infusion of calcium borogluconate without magnesium hypophosphite made all three cows anorexic and hypercalcaemic and the slow infusion made 1/3 anorexic. It is concluded that the IV administration of a calcium solution containing magnesium hypophosphite does not increase the serum concentration of inorganic phosphorus.
Animals↗
Inductive electron-withdrawal from ammonium ion headgroups of cationic lipids and the influence on DNA transfection.
We have prepared a panel of lipidic ammonium tetrafluoroborate salts that contain trifluoromethyl, trichloromethyl, and methyl groups attached to the headgroup. 19F-NMR analyses of the cationic lipid panel revealed that the differences in electron-withdrawal from the ammonium ion headgroup accounted for differences in ion-pairing. Exchange of the tetrafluoroborate counterion by complexation to DNA-phosphate of a reporter gene enabled us to probe the influence of inductive electron-withdrawal in cationic lipid-mediated DNA transfection. We tested the lipid panel for transfection activity in two cell lines. The results indicate that the inductive effects of electron-withdrawing functionality diminish transfection activity in modest (2-4-fold) increments. The present study suggests that the mechanism whereby poly(alcohol)- or poly(ether)-substituted headgroups improve DNA transfection is not based on electronic activation of the ammonium ion.
Adenocarcinoma↗