1.Determination of ten monohydroxylated polycyclic aromatic hydrocarbons by liquid-liquid extraction and liquid chromatography/tandem mass spectrometry.
Fan R1, Ramage R, Wang D, Zhou J, She J. Talanta. 2012 May 15;93:383-91. doi: 10.1016/j.talanta.2012.02.059. Epub 2012 Mar 1.
The aim of this study is to develop and validate an analytical method for the quantitation of ten urinary monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) through high pressure liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). After enzymatic deconjugation, urine samples were extracted by liquid-liquid extraction (LLE) and OH-PAHs were analyzed by HPLC/MS/MS operated in negative electrospray ionization (ESI) and multiple reaction monitoring (MRM) mode. LLE was conducted with the solvent mixture of pentane and toluene, which reduced the matrix interferences and enhanced the method sensitivity significantly. Deuterated and (13)C-labeled analogs are used as internal standards. Calibration curves of all target analytes shows favorable linearity within the concentration range of 5.9-15,000.0 ng/L for different OH-PAHs with the regression coefficients above 0.993. The limits of detection (LODs) in pooled urine ranged from 1.
2.High-throughput semi-automated 96-well liquid/liquid extraction and liquid chromatography/mass spectrometric analysis of everolimus (RAD 001) and cyclosporin a (CsA) in whole blood.
Brignol N1, McMahon LM, Luo S, Tse FL. Rapid Commun Mass Spectrom. 2001;15(12):898-907.
A semi-automated high-throughput liquid/liquid extraction (LLE) assay was developed for RAD001 and cyclosporin A (CsA) in human blood. After addition of internal standard and ammonium hydroxide, samples were extracted twice with methyl tert-butyl ether (MTBE). The organic extract was evaporated to dryness and reconstituted in mobile phase. Where possible, sample transfer and LLE steps were automated using a Tomtec Quadra 96 workstation. Samples were analyzed using ESI-LC/MS/MS employing the transitions of ([M + NH(4)](+) --> [M + H](+)) for CsA and ([M + NH(4)](+) --> [M + H-(CH(3)OH + H(2)O)](+)) for RAD001, under isocratic chromatographic conditions (75:25, (v/v), acetonitrile/20 mM ammonium acetate) with a run time of 3.6 min. A lower limit of quantitation (LLOQ) of 0.368 ng/mL and 5.23 ng/mL was achieved for RAD001 and CsA, respectively, using a sample volume of 0.3 mL for the analysis. The method was validated over a 3-day period and the resulting calibration curves had a correlation coefficient >0.
3.Isolation and characterization of insulin from the Brockmann body of Dissostichus mawsoni, an Antarctic teleost fish.
Bachle LA1, Smith DD, Petzel D. J Pept Res. 2000 Jul;56(1):47-54.
The Brockmann body of fish synthesizes and secretes insulin. The Brockmann body of Antarctic fish has been described anatomically and shown to contain insulin immunoreactive sites, however, the primary structure of an Antarctic fish insulin has yet to be reported. Insulin was isolated from the Brockmann bodies of the Antarctic perciform teleost, Dissostichus mawsoni. The peptide was purified to homogeneity by gel filtration and reversed-phase HPLC. Insulin-containing fractions were identified by radioimmunoassay using antisera raised against porcine insulin. Electrospray ionization-mass spectrometry determined the mass of the isolated product to be 5725.27 a.m.u. The amino acid composition and primary structure were determined for the pyridylethylated A- and B-chains. The amino acid sequences of the A chain and B chain were H-Gly-lle-Val-Glu-Gln-Cys-Cys-His-Gln-Pro10-Cys-Asn-Ile-Phe- Asp-Leu-Gln-Asn-Tyr-Cys20-Asn-OH and H-Ala-Pro-Gly-Pro-GIn-His-Leu-Cys-Gly-Ser10-His-Leu-Val-Asp-Ala-Le u-Tyr-Leu-Val-Cys20-Gly-Glu-Arg-Gly-Phe-Phe-Tyr-Asn-Pro-Lys30++ +-OH, respectively.
4.Effects of arginase inhibitors on the contractile and relaxant responses of isolated human penile erectile tissue.
Lorenzen JM1, Ückert S, Scheller F, Haller H, Kuczyk MA. World J Urol. 2009 Dec;27(6):805-10. doi: 10.1007/s00345-009-0405-1.
OBJECTIVES: An impairment in the local availability of nitric oxide (NO) may impair male erectile function. The activity of l-arginine-degrading arginase enzymes may attenuate the relaxation of cavernous smooth muscle by reducing local NO production. Arginase enzymes compete with the nitric oxide synthases for the common substrate, the amino acid l-arginine. Very little data are available regarding the significance of arginase enzymes in the control of human penile erectile tissue. The aim of the present study was to elucidate the effects of drugs known to inhibit arginase activity on the relaxation of isolated human corpus cavernosum (HCC) and the production of cyclic GMP.
