196,055 research outputs found
Analisi dello Stanozololo e suoi metaboliti in urine bovine mediante LC-MS-MS
No full textC.N.R.-AREA DELLA RICERCA DI ROMA
Stanozolol metabolites by LC-MS-MS
No full textThis paper describes the optimization of the detection of stanozolol and its major metabolite in bovine urine by HPLC-MS-MS. Urine is first submitted to enzymic hydrolysis and then extd. by solid phase with two cartridges. Detection is carried out by HPLC-MS-MS in multiple reaction monitoring. Recovery of the method is around 80% for the three main stanozolol metabolites. Limit of detection of the compds. is below the criteria proposed by National Residue Plan
Development of a liquid chromatography-tandem mass spectrometry method for the identification of natural androgen steroids and their conjugates in urine samples
No full textAn anal. procedure for the detn. of natural steroids and their conjugates was developed and applied to bovine and human urine. Fifteen compds. (free and conjugated) after extn. by solid-phase were identified by liq. chromatog.-tandem mass spectrometry (LC-MS-MS) in multiple reaction monitoring (MRM). Free and conjugated steroids were detected all together in the same chromatog. anal. resp. in pos. and neg. ionization. This procedure reveals to be time-saving, because it overcomes the need of further sample pre-treatment steps, such as enzymic hydrolysis and derivatization. The recovery for each compd. was around 80%. Limit of detection of each steroid free or conjugated has been evaluated
Identification of hydroxycinnamic acid-tartaric acid esters in wine by HPLC-tandem mass spectrometry
No full textIn this work hydroxycinnamic acid esters of tartaric acid (mono-p-coumaroyl tartaric acid, monocaffeoyl tartaric acid, monoferuloyl tartaric acid esters) were separated, identified and quantified in several red wines by high performance liquid chromatography coupled with tandem mass spectrometry. The method features direct analysis of wines with no preparation and analysis of grape juice with minimum sample manipulation. For the identification was used both a triple quadrupole and a quadrupole-Tof, while for the quantification a triple quadrupole. At the same time two impurities, due to interfering substances coming from methanol (stored in bottles with polypropylene tops without Teflon protection), were characterised. These impurities had the same molecular weight as the investigated compounds. (C) 2010 Elsevier Ltd. All rights reserved
Glioblastoma cells do not affect axitinib‐ dependent senescence of HUVECs in a transwell coculture model
No full textAxitinib is an orally available inhibitor of tyrosine kinases, with high specificity for vascular endothelial growth factor receptors (VEGFRs) 1, 2, and 3. It is approved for the treatment of advanced renal cell carcinoma and is in phase II clinical trials for recurrent glioblastoma (GBM). GBM is a brain tumor peculiar in its ability to induce neoangiogenesis. Since both GBM tumor cells and endothelial cells of tumor vasculature express VEGFRs,Axitinib exerts its inhibitory action on both tumor and endothelial cells. We and others previously demonstrated that Axitinib triggers cellular senescence. In particular, Axitinib‐dependent senescence of HUVECs (human umbilical vein endothelial cells) is accompanied by intracellular reactive oxygen species(ROS) increase and early ataxia telangiectasia mutated(ATM) activation. Here we wondered if the presence of glioblastoma tumor cells could affect the HUVEC senescence upon Axitinib exposure. To address this issue, we cocultured HUVECs together with GBM tumor cells in transwell plates. HUVEC senescence did not result in being affected by GBM cells, neither in terms of β galactosidase activity nor of proliferation index or ATM phosphorylation. Conversely, Axitinib modulation of HUVEC gene expression was altered by cocultured GBM cells. These data demonstrate that the GBM secretome modifies HUVECs’ transcriptomic profile upon Axitinib exposure, but does not prevent drug‐induced senescence
Chromatographic analysis of trans resveratrol in Italian wines: Comparisons between FL, UV and MS detection
No full textResveratrol (3,5,4'-trihydroxystilbene) is a phytoalexin that belongs to the group of stilbenes, known to occur in gropes and consequently in grape products. Its presence in wine is an important qualitative parameter because of the several beneficial effects on human health. The aim of this work is the development of a high-performance liquid chromatographic (HPLC) method for the determination of trans resveratrol in wines, and comparisons between the results obtained by different detection techniques: UV-vis spectroscopy, fluorescence spectroscopy and mass spectrometry. Resveratrol is analysed on a C-18 column using gradient elution. The method permits direct injection of sample, revealing to be time-saving, overcoming the need of sample pre-treatment steps. Detection limits were 154.8 ng mL(-1) by HPLC-UV, 118.0 ng mL(-1) by HPLC-FL and 48.0 ng mL(-1) by HPLC-MS. Trans resveratrol has been then quantified in a group of 52 wines derived from different Italian regions, cultivars and winemaking technologies by HPLC-UV
Gene expression profiling of hypoxic response in different models of senescent endothelial cells
No full textEndothelial cells senescence is a physiological process affecting vascular integrity. It can contribute to heart and arterial stiffening and remodeling, impaired angiogenesis, defective vascular repair, and with an increasing prevalence of atherosclerosis. Drugs used as antineoplastic therapies, targeting tumor as well as endothelial cells, can also trigger endothelial cells senescence. We demonstrated that a short pulse of axitinib, a specific inhibitor of vascular endothelial growth factor receptors, induces cell senescence of endothelial cells. Here, we performed a high-throughput gene expression analysis to characterize the response of proliferating versus senescent endothelial cells to hypoxia, the main trigger of neo-angiogenetic phenomena in tumors. We compared the response to hypoxia of replicative senescent cells, with that of axitinib or of DNA damage-induced senescence. Overall, we enlightened common and specific responses to different senescence inducers and changes in the Senescent Associated Secretory Phenotype
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Intracellular magnesium content changes during mitochondria-mediated apoptosis: in depth study of early events on mitochondrial membrane potential
No full textA recent study showed the antitumor activity of a new indole-derivative – MM-67 – inducing mitochondria-mediated apoptosis and a decrease of intracellular magnesium (Mg) concentration in HT29 colon cancer cells. Aim of this work was to assess cellular Mg levels throughout MM-67-induced apoptosis from the early to the final stage of the process and to evaluate the correlation with mitochondrial membrane potential (ΔΨm) variations. All analysis were performed by flow cytometry: ΔΨm was assessed by using mitochondrial potential sensitive dye DiOC6, while free and total intracellular cation concentrations were assessed by using the commercial probe MagFluo4-AM (Kd=4.7 mM), and the new synthesized DCHQ5 (Kd=8.3 mM), respectively. Our results evidenced that the MM67 induced apoptosis is characterized by a direct correlation between ΔΨ and free intracellular Mg content variations
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