Biomedical subjects

Haoyang Wang

Publications and source records attributed to Haoyang Wang.

7 recordsLinked to original sources

PubMed2007

Study of methylation of nitrogen-containing compounds in the gas phase.

The methyl migration between the protonated N,N-dimethylisopropylamine and other neutral aliphatic amines in the gas phase has been investigated by a hybrid external chemical ionization source ion trap mass spectrometer. Similar reactions have been found in the aqueous solution by Callahan and Wolfenden (J. Am. Chem. Soc. 2003; 125: 310). At the same time, density functional theory (DFT) calculations show that in contrast with the neutral N,N-dimethylisopropylamine, protonated N,N-dimethylisopropylamine is a better methyl donor. These results indicate that protonation promotes the methyl migration between aliphatic amines both in the gas phase and in the aqueous solution. In addition, methyl transfer also exists between the protonated N,N-dimethylisopropylamine and some other nitrogen-containing compounds.

Gases↗

PubMed2006

Induction of lactoferrin and IL-8 release from human neutrophils by tryptic enzymes via proteinase activated receptor-2.

Tryptic enzymes such as tryptase, trypsin and thrombin are reportedly able to alter neutrophil behavior. However, little is known of the influence of these proteinases on lactoferrin or IL-8 release from neutrophils. In the present study, we investigated the effects of tryptase, trypsin, thrombin and elastase, and agonist peptides of PAR-1 SFLLR-NH(2) and PAR-2 SLIGKV-NH(2) and tc-LIGRLO-NH(2) on lactoferrin and IL-8 release from highly purified human neutrophils. Flow cytometry shows CD16(+) neutrophils express PAR-1 and PAR-2, but not PAR-3 and PAR-4 proteins. RT-PCR analysis reveals that neutrophils express only PAR-2 genes. Tryptase and trypsin, but not thrombin and elastase, induced significant lactoferrin and IL-8 secretion from neutrophils. SLIGKV-NH(2) and tc-LIGRLO-NH(2), but not SFLLR-NH(2), also stimulated lactoferrin and IL-8 secretion from neutrophils. In conclusion, only a proportion of neutrophils express PAR-1 and/or PAR-2. Tryptase and trypsin-induced lactoferrin and IL-8 secretion from neutrophils most likely occur through activation of PAR-2.

Humans↗

PubMed2006

Studies of gas-phase fragmentation reactions of [Pd(PPh3)2(OCOR)]+ by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

Gas-phase fragmentation reactions of [Pd(PPh3)2(OCOR)]+ (R = H, CH3, CD3, C2H5, n-C3H7, n-C6H13 and C6H5) were studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS). In sustained off-resonance irradiation collision-activated dissociation (SORI-CAD) experiments, the complexes all dissociated to yield the same product ion at m/z 629.1. We propose that the fragmentation pathway occurs through the elimination of RCOOH and a palladium(IV) hydride intermediate. Semi-empirical (PM3) calculations shed light on the mechanism for the fragmentation reactions of these compounds. The results of deuterium-labeling experiments indicate that the protons of RCOOH lost from [Pd(PPh3)2(OCR)]+ originate from the phenyl in the triphenylphosphine ligand. [Pd(PPh3)2(OCOH)]+ undergoes two competitive pathways in SORI-CAD experiments, one of which is similar to that of [Pd(PPh3)2(OCOR)]+ (R = CH3, CD3, C2H5, n-C3H7, n-C6H13 and C6H5), and the other involves decarboxylation. The present study demonstrates that MS could play an important role in studying the gas-phase chemistry of palladium hydrides.

Journal Article↗

PubMed2006

Interception of the radicals produced in electrophilic fluorination with radical traps (Tempo, Dmpo) studied by electrospray ionization mass spectrometry.

The interaction of the nitroxide radical traps (Tempo and Dmpo) and radicals produced in the electrophilic fluorination of olefins (styrene and alpha-methylstyrene) and Selectfluor (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octanebis(tetrafluoroborate) (F-TEDA-BF(4)) (1)) was investigated by electrospray ionization mass spectrometry (ESI-MS). Tempo succeeded in intercepting the radical cationic intermediates and the radical adduct ions were detected at m/z 260 (for styrene) and m/z 274 (for alpha-methylstyrene). Dmpo could also intercept the fluorine radical and radical adduct ions were detected at m/z 131, 132 and 152. The interception of the radical cationic intermediates and fluorine radical is good evidence for the presence of a single-electron transfer mechanism in the electrophilic fluorination.

Fluorine↗

PubMed2005

Investigation of radical cation in electrophilic fluorination by ESI-MS.

Reaction solutions of selectfluor (1) with triphenylethylene (4a) and tetraphenylethylene (4b) were monitored by ESI-MS and ESI-MS/MS. Detection and characterization of the key radical cationic intermediates 5a.+ and 5b.+) fully supports the SET mechanism in electrophilic fluorination as depicted above. [reaction: see text]

Journal Article↗

PubMed2005

Identification of volatile basic components in tobacco by headspace liquid-phase microextraction coupled to matrix-assisted laser desorption/ionization with Fourier transform mass spectrometry.

A method incorporating headspace liquid-phase microextraction (HS-LPME) coupled to matrix-assisted laser desorption/ionization (MALDI) with Fourier transform mass spectrometry (FTMS) was established to analyze volatile basic components in tobacco. The sample preparation volume for MALDI-MS was compatible with the volume of the solvent microdrop in the HS-LPME procedure. The pH and the polarity of the solvent for HS-LPME were adjusted by choice of the MALDI matrix and matrix additive. Based on the elemental composition and tandem mass spectrometry information, 25 volatile nitrogenous compounds in tobacco were detected and identified. The approach is fast and sensitive, and has the potential for automation for high-throughput analysis. This approach offers an alternative method for analysis of trace volatile organic compounds in complex samples.

Gas Chromatography-Mass Spectrometry↗

PubMed2005

CD226 is expressed on the megakaryocytic lineage from hematopoietic stem cells/progenitor cells and involved in its polyploidization.

OBJECTIVES: In this study, we examined the expression of CD226 on megakaryocytic, granulocytic and erythroid lineage from hematopoietic stem cells/progenitor cells in adult and fetus and its potential role in megakaryocytic maturation. METHODS: CD34(+) cells from adult and fetus were induced to differentiate toward the megakaryocytic lineage by thrombopoietin (TPO) and the granulocytic lineage by granulocyte colony-stimulating factor (G-CSF), respectively. Mononuclear cells from fetal liver and CD34(+) cells from adult were induced to differentiate toward erythroid-lineage by erythropoiesis (EPO). We investigated the expression of CD226 and lymphocyte function associated antigen-1 (LFA-1) (CD11a) during hemopoiesis. We also studied the effect of CD226 monoclonal antibody (MoAb) and LFA-1 MoAb on megakaryocyte with antibody cross-liking technique. RESULTS: CD34(+) cells from adult and fetus and TPO-induced CD41(+) cells all expressed CD226 molecule. CD226 was not expressed on erythroid progenitor cells and erythroblasts and most cells of granulocytic lineage although G-CSF induced a significant increase of the expression of CD226 on CD34(+) cells in early period of time. CD226 MoAb acts on megakaryocytes by inducing intracellular calcium mobilization. The expression of LFA-1 decreased significantly at late stage of differentiation and maturation of fetal megakaryocytes whereas the expression of LFA-1 on adult megakaryocytes retained at a high level. CD226 MoAb in combination with LFA-1 MoAb shifted the ploidy of generated megakaryocytes from adult-derived CD34(+) cells to higher classes significantly although CD226 and LFA-1 MoAb slightly increased the ploidy of the generated megakaryocytes individually. CD226 MoAb or LFA-1 MoAb or CD226 MoAb plus LFA-1 MoAbs did not increase the ploidy of the generated megakaryocytes from fetus-derived CD34(+) cells. CONCLUSION: CD226 molecules play an important role in maturation of the megakaryocytes in combination with LFA-1.

Adult↗