PubMed · 12398179
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Marten Szibor, Henning Morawietz. 2002. Serial competitive RT-PCR using multiple standards.. https://doi.org/10.2144/02334bm05
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Protein tyrosine phosphorylation cascades are difficult to analyze and are critical for cell signaling in higher eukaryotes. Methodology for profiling tyrosine phosphorylation, considered herein as the assignment of multiple protein tyrosine phosphorylation sites in single analyses, was reported recently (Salomon, A. R.; Ficarro, S. B.; Brill, L. M.; Brinker, A.; Phung, Q. T.; Ericson, C.; Sauer, K.; Brock, A.; Horn, D. M.; Schultz, P. G.; Peters, E. C. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 443-448). The technology platform included the use of immunoprecipitation, immobilized metal affinity chromatography (IMAC), liquid chromatography, and tandem mass spectrometry. In the present report, we show that when using complex mixtures of peptides from human cells, methylation improved the selectivity of IMAC for phosphopeptides and eliminated the acidic bias that occurred with unmethylated peptides. The IMAC procedure was significantly improved by desalting methylated peptides, followed by gradient elution of the peptides to a larger IMAC column. These improvements resulted in assignment of approximately 3-fold more tyrosine phosphorylation sites, from human cell lysates, than the previous methodology. Nearly 70 tyrosine-phosphorylated peptides from proteins in human T cells were assigned in single analyses. These proteins had unknown functions or were associated with a plethora of fundamental cellular processes. This robust technology platform should be broadly applicable to profiling the dynamics of tyrosine phosphorylation.
Human umbilical vein endothelial cells (HUVEC) express and synthesize both constitutive and inducible nitric oxide synthase (NOS) and cyclo-oxygenase (COX) enzymes, and have been extensively used as an in vitro model to investigate the role of these enzymes in the patho-physiology of placenta-fetal circulation. In this study we investigated the role of NO in regulating prostanoid production and release from HUVEC. Both untreated and IL-1beta-treated HUVEC were exposed to various NOS inhibitors and NO donors in short-term (1 or 3 hours) experiments, and the effects on prostanoid production were evaluated through the measurement of prostaglandins (PG) I2, E2 and F2alpha released in the incubation medium. We found that the inhibition of inducible NOS but not endothelial NOS antagonizes the IL-1beta-induced increase in PGI2 release. However, NOS inhibitors do not modify baseline PGI2 production. Pharmacological levels of NO, obtained with various NO donors, inhibit basal and IL-1beta-stimulated PG release.
We have assessed a cell fluid chip-based fluorescent cytometric assay that runs on bioanalyzer for fast characterization of small population cell phenotypes characterization. The assay determines the expression of specific cell surface markers on various cell samples. Six samples can be analyzed on each chip in one automated process. Results were in good agreement with conventional flow cytometry in quantitation. Importantly, this procedure used less than 200 cells per sample and produced results consistent with that using 10(5) cells by the conventional staining procedure. The method was also used for screening potential ingredients in herbs. Purpose of this study was to analyze the change of cell subtypes of UCB mononuclear cells in vitro reactivity in herbs. We found that by treatment of the water-soluble extract (F3) of Ganoderma lucidum, the presence of CD56(+) marker (natural killer cells) significantly increased from 1.1 to 3.2% (P<0.05 and P) in UCB mononuclear cells. The results indicated that F3 quantitatively influenced NK cells activities. We suggest this screening method may be useful for a fast phenotypes characterization after extract stimulation utilizing only a small population of cells.