Tissue sulfate determination by ion chromatography

Differentially expressed genes in Bordetella pertussis strains belonging to a lineage which recently spread globally

Pertussis is a highly contagious, acute respiratory disease in humans caused by the Gram-negative pathogen Bordetella pertussis. Pertussis has resurged in the face of intensive vaccination and this has coincided with the emergence of strains carrying a particular allele for the pertussis toxin promoter, ptxP3, which is associated with higher levels of pertussis toxin (Ptx) production. Within 10 to 20 years, ptxP3 strains have nearly completely replaced the previously dominant ptxP1 strains resulting in a worldwide selective sweep. In order to identify B. pertussis genes associated with the selective sweep, we compared the expression of genes in ptxP1 and ptxP3 strains that are under control of the Bordetella master virulence regulatory locus (bvgASR). The BvgAS proteins comprise a two component sensory transduction system which is regulated by temperature, nicotinic acid and sulfate. By increasing the sulfate concentration, it is possible to change the phase of B. pertussis from virulent to avirulent. Until recently, the only distinctive phenotype of ptxP3 strains was a higher Ptx production. Here we identify additional phenotypic differences between ptxP1 and ptxP3 strains which may have contributed to its global spread by comparing global transcriptional responses under sulfate-modulating conditions. We show that ptxP3 strains are less sensitive to sulfate-mediated gene suppression, resulting in an increased production of the vaccine antigens pertactin (Prn) and Ptx and a number of other virulence genes, including a type III secretion toxin, Vag8, a protein involved in complement resistance, and lpxE involved in lipid A modification. Furthermore, enhanced expression of the vaccine antigens Ptx and Prn by ptxP3 strains was confirmed at the protein level. Identification of genes differentially expressed between ptxP1 and ptxP3 strains may elucidate how B. pertussis has adapted to vaccination and allow the improvement of pertussis vaccines by identifying novel vaccine candidates.

Using Carbon Nanotubes to Absorb Low-Concentration Hydrogen Sulfide in Fluid

Hydrogen sulfide is a colorless and flammable gas under room temperature. Usually hydrogen sulfide is considered to be toxic; however, the recent research revealed that hydrogen sulfide in the cardiovascular system plays the role of a vascular dilator. The physiological role of hydrogen sulfide depends on its in vivo level. As such, the measurement of hydrogen sulfide with nano-quantity resolution becomes an important subject. Existing methods generally require bulky samples and are invasive and offline. It will be significantly helpful to measure hydrogen sulfide with a small amount of tissue in a noninvasive method The first attempt was to take a blood or serum sample with a trace amount to examine the interaction between hydrogen sulfide and carbon nanotube. The carbon nanotube is chosen because of a known fact that hydrogen sulfide can be adsorbed by activated carbon. The carbon nanotube is an excellent activated carbon in this regard. Fluorescence intensity of the carbon nanotube with and without immersion of it in a hydrogen sulfide medium was examined in the study. It was found that the intensities increase as the concentrations of hydrogen sulfide increase. Furthermore, the concentration of 10 microM hydrogen sulfide in water was successfully measured.

Thyrotropin and iodide regulate sulfate concentration in thyroid cells. Relationship to thyroglobulin sulfation

Thyroglobulin (Tg), the thyroid hormone precursor, is sulfated both on tyrosines and on carbohydrates. We showed recently that sulfated tyrosines were involved in thyroid hormone synthesis. Moreover, we also reported that Tg sulfation is downregulated by thyrotropin (TSH), especially on tyrosines. This control may occur at each step in the sulfation process. In this paper, we studied the regulation of the concentration of cytosolic inorganic sulfate, the first substrate, in porcine thyroid cells stimulated by TSH with or without iodide. The amounts of cytosolic sulfate and the cytosolic volumes measured showed that the sulfate concentration depends only on cytosolic volume changes in response to TSH and iodide treatment. After the cells were labelled with [35S]-sulfate, the specific radioactivity (SRA) of cytosolic sulfate was determined. When cells were treated with only TSH, the concentration and SRA of cytosolic sulfate decreased by 30%, and by about 15% when cells were incubated with both TSH and iodide. TSH decreased more conspicuously the rate of [35S]-sulfate incorporation into Tg (by 57% without iodide, by 43% with iodide) than the concentration and SRA of cytosolic sulfate, while iodide altered these parameters to the same extent (15%). These findings suggest that TSH regulates other steps in the sulfation process, such as specific substrate and enzyme levels, while iodide controls mainly the sulfate concentration.Key words: cytosolic inorganic sulfate measurement, capillary electrophoresis, intracellular sulfate concentration, thyroglobulin sulfation, primary culture thyroid cells.

State-of-the-art ion chromatographic determination of inorganic ions in food

A review of the applications of ion chromatography (IC) to the determination of inorganic ions in food is presented. The most promising sample preparation techniques, such as accelerated solvent extraction, supercritical fluid extraction, solid-phase extraction, UV photolysis, microwave-oven digestion and pyrohydrolysis are discussed. Among the various inorganic anions, nitrogen, sulphur and phosphorus species and halides are widely determined in foods and to a lesser extent only, cyanide, carbonate, arsenic and selenium species are considered. IC determination of inorganic cations deals with ammonium ion, alkali, alkaline-earth, heavy and transition metals particularly and only a small amount of literature is found on the other ones, like aluminium and plantinum. A particular advantage of IC over traditional techniques is the simultaneous determination of several species.

Plasma level determination of 1,4-butanedisulphonate by ion chromatography and conductimetric detection

A rapid, specific and reproducible liquid chromatographic method was developed for the determination of 1,4-butanedisulphonate in plasma. The method involves protein precipitation with perchloric acid, precipitation of perchlorate ions by addition of potassium carbonate followed by ion chromatography on an ion-exchange column connected with a conductimetric detector. Calibration graphs were linear over the concentration range 2.5-25 micrograms/ml; the intra-assay precision was < or equal to 3.6% and the inter-assay precision was < or equal to 5.8%. The analyte was stable in plasma and in perchloric acid at 37 degrees C for 24 h. The assay procedure was applied to monitoring plasma levels in animals receiving chronic intravenous and oral administration of the analyte.