Biomedical subjects

Y Chen

Publications and source records attributed to Y Chen.

At least 91 records · Page 5Linked to original sources

PubMed2005

Comparison of the effects of intravenously and orally administered esomeprazole on acid output in patients with symptoms of gastro-oesophageal reflux disease.

BACKGROUND: Intravenous esomeprazole may be beneficial for patients who cannot take oral medications. AIM: To compare intravenous esomeprazole with oral esomeprazole for effects on maximal acid output during pentagastrin stimulation in patients with gastro-oesophageal reflux disease symptoms. METHODS: In four separate open-label, randomized, two-way crossover studies, adult patients were administered esomeprazole 20 or 40 mg once daily either orally or intravenously (by 15-min infusion or 3-min injection) for 10 days and switched to the other formulation with no washout period. Basal acid output and maximal acid output were measured on days 11, 13 and 21. RESULTS: In the four studies (total of 183 patients), least-squares mean maximal acid output ranged from 3.0 to 4.1 mmol/h after intravenous esomeprazole 40 or 20 mg and from 2.2 to 3.3 mmol/h after oral esomeprazole 20 or 40 mg. Differences between formulations were small and not statistically significant but did not meet the prospectively defined criterion for non-inferiority of the intravenous formulation. Median basal acid output values ranged from 0.04 to 0.27 mmol/h after intravenous administration and from 0.05 to 0.25 mmol/h after oral esomeprazole. CONCLUSIONS: Intravenous esomeprazole is an acceptable alternative to the oral formulation for treatment of up to 10 days of duration.

Administration, Oral↗

PubMed2005

hCG Secretion in human choriocarcinoma JAR cells is MAPK but not Stat3 dependent: contributions of TNFalpha and IL-1beta to inflammation-induced hCG secretion.

Inflammatory mediators play critical physiologic roles throughout the course of normal pregnancy. At the same time, uncontrolled inflammation appears to have an adverse affect on pregnancy outcome. Thus, a crucial task of reproductive immunology is to define the mechanisms through which inflammation is controlled at the maternal-fetal interface. We examined the signaling pathways activated in the human choriocarcinoma cell line, JAR, in response to an in vitro model of an inflammatory challenge. We incubated JAR cells with medium from peripheral blood mononuclear cells (PBMC) that had been activated with either LPS or PHA. Conditioned medium from each experimental model induced MAP kinase and Stat3 phosphorylation as well as human chorionic gonadotropin (hCG) secretion from JAR cells. hCG secretion could be blocked by pharmacologic inhibition of MAP kinase but not by inhibition of Stat3 using an siRNA approach. The MAPK activators IL-1beta and TNFalpha both induced hCG secretion from JAR cells, but not the Stat3 activators IFN-gamma and IL-6. Furthermore, hCG secretion induced by conditioned media could be blocked by IL-1 receptor antagonist. We conclude that inflammation at the maternal-fetal interface may involve complex webs of regulatory and counter-regulatory mechanisms that involve multiple cytokines and at least two major, independent cell-signaling systems.

Cell Line, Tumor↗

PubMed2005

Distributions of charged hadrons associated with high transverse momentum particles in pp and Au+Au collisions at sqrt[sNN]=200 GeV.

Charged hadrons in [EQUATION: SEE TEXT] associated with particles of [EQUATION: SEE TEXT] are reconstructed in pp and Au+Au collisions at sqrt[sNN]=200 GeV. The associated multiplicity and p magnitude sum are found to increase from pp to central Au+Au collisions. The associated p distributions, while similar in shape on the nearside, are significantly softened on the awayside in central Au+Au relative to pp and not much harder than that of inclusive hadrons. The results, consistent with jet quenching, suggest that the awayside fragments approach equilibration with the medium traversed.

Journal Article↗

PubMed2005

Doppler shift as a tool for studies of isobaric analog states of neutron-rich nuclei: application to 7He.

We have developed a new technique to study exotic neutron-rich nuclei via their isobaric analog states (IAS). We populate high-isospin states in resonant reactions of radioactive ion beams with protons. Characteristic gamma rays emitted from excited decay products were used to identify the population of the IAS. We show that information on the differential and total cross section for formation of the IAS can be extracted from the energy spectrum of the Doppler-shifted gamma rays. This technique was applied to the study of T=3/2 states in 7Li, which are analogs of states in 7He. The analog of the 7He ground state was clearly observed, whereas the presence of the analog of a narrow 1/2(-) state at 0.6 MeV excitation in 7He reported by M. Meister et al. [Phys. Rev. Lett. 88, 102501 (2002)] was excluded at the 90% confidence level. Evidence is presented for a broad 1/2(-) state at a higher excitation energy in 7He.

Journal Article↗

PubMed2005

Identification and quantitation of eleven sesquiterpenes in three species of Curcuma rhizomes by pressurized liquid extraction and gas chromatography-mass spectrometry.

In this paper, GC-MS and pressurized liquid extraction (PLE) was developed for identification and quantitative determination/estimation 11 sesquiterpenes including germacrene D, curzerene, gamma-elemene, furanodienone, curcumol, isocurcumenol, furanodiene, germacrone, curdione, curcumenol and neocurdione in Ezhu which are derived from three species of Curcuma, i.e., Curcuma phaeocaulis, Curcuma wenyujin and Curcuma kwangsiensis by using an analogue as standard. The results showed the methodology could quantitatively compare the quality of three species of Curcuma. The contents of investigated sesquiterpenes in three species of Curcuma were high variant. Hierarchical clustering analysis based on characteristics of 11 identified peaks in GC profiles showed that 18 samples were divided into two main clusters, C. phaeocaulis and C. wenyujin, respectively. C. kwangsiensis showed the characters closed to C. phaeocaulis or C. wenyujin based on its location. Five components such as furanodienone, germacrone, curdione, curcumenol and neocurdione were optimized as markers for quality control of Ezhu.

Chemistry, Pharmaceutical↗

PubMed2005

Comparison of surfactant lipids between pleural and pulmonary lining fluids.

Saturated phospholipids (PCs), particularly dipalmitoylphosphatidylcholine (DPPC), predominate in surfactant lining the alveoli, although little is known about the relationship between saturated and unsaturated PCs on the outer surface of the lung, the pleura. Seven healthy cats were anesthetized and a bronchoalveolar lavage (BAL) was performed, immediately followed by a pleural lavage (PL). Lipid was extracted from lavage fluid and then analyzed for saturated, primarily dipalmitoylphosphatidylcholine (DPPC), and unsaturated PC species using high-performance liquid chromatography (HPLC) with combined fluorescence and ultraviolet detection. Dilution of epithelial lining fluid (ELF) in lavage fluids was corrected for using the urea method. The concentration of DPPC in BAL fluid (85.3+/-15.7 microg/mL) was significantly higher (P=0.021) than unsaturated PCs ( approximately 40 microg/mL). However, unsaturated PCs ( approximately 34 microg/mL), particularly stearoyl-linoleoyl-phosphatidylcholine (SLPC; 17.4+/-6.8), were significantly higher (P=0.021) than DPPC (4.3+/-1.8 microg/mL) in PL fluid. These results show that unsaturated PCs appear functionally more important in the pleural cavity, which may have implications for surfactant replenishment following pleural disease or thoracic surgery.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2005

Multistrange Baryon elliptic flow in Au+Au collisions at square root of sNN=200 GeV.

We report on the first measurement of elliptic flow v2(pT) of multistrange baryons Xi- +Xi+ and Omega- + Omega+ in heavy-ion collisions. In minimum-bias Au+Au collisions at square root of s(NN)=200 GeV, a significant amount of elliptic flow, comparable to other nonstrange baryons, is observed for multistrange baryons which are expected to be particularly sensitive to the dynamics of the partonic stage of heavy-ion collisions. The pT dependence of v2 of the multistrange baryons confirms the number of constituent quark scaling previously observed for lighter hadrons. These results support the idea that a substantial fraction of the observed collective motion is developed at the early partonic stage in ultrarelativistic nuclear collisions at the Relativistic Heavy Ion Collider.

Journal Article↗

PubMed2005

Antibody mimics based on human fibronectin type three domain engineered for thermostability and high-affinity binding to vascular endothelial growth factor receptor two.

The tenth human fibronectin type three domain ((10)Fn3) is a small (10 kDa), extremely stable and soluble protein with an immunoglobulin-like fold, but without cysteine residues. Selections from (10)Fn3-based libraries of proteins with randomized loops have yielded high-affinity, target-specific antibody mimics. However, little is known about the biophysical properties of such antibody mimics, which will determine their suitability for in vitro and medical applications. We characterized target binding and biophysical properties of two related (10)Fn3-based antibody mimics that bind vascular endothelial growth factor receptor two (VEGF-R2). The first antibody mimic, which has a dissociation constant (K(d)) of 13 nM, is highly stable [melting temperature (T(m))=62 degrees C] and soluble, whereas the second, which binds VEGF-R2 with 40 x higher affinity, is less stable (T(m) < 40 degrees C) and relatively insoluble. We used our understanding of these two (10)Fn3 derivatives and of wild-type (10)Fn3 structure to engineer the next generation of antibody mimics, which have an improved combination of high affinity (K(d)=0.59 nM), stability (T(m)=53 degrees C) and solubility. Our findings illustrate that (10)Fn3-based antibody mimics can be engineered for favorable biophysical properties even when 20% of the wild-type (10)Fn3 sequence is mutated in order to satisfy target-binding requirements.

Amino Acid Sequence↗

PubMed2005

Multiplicity and pseudorapidity distributions of photons in Au+Au collisions at square root of (S(NN)) = 62.4 GeV.

We present the first measurement of pseudorapidity distribution of photons in the region 2.3 < or = eta < or = 3.7 for different centralities in Au+Au collisions at square root of (S(NN)) = 62.4 GeV. We find that the photon yield scales with the number of participating nucleons at all collision centralities studied. The pseudorapidity distribution of photons, dominated by pi0 decays, has been compared to those of charged pions, photons, and inclusive charged particles from heavy-ion and nucleon-nucleon collisions at various energies. The photon production has been shown to be consistent with the energy and centrality independent limiting fragmentation scenario.

Journal Article↗

PubMed2005

Mechanism of the defect in gap-junctional communication by expression of a connexin 26 mutant associated with dominant deafness.

Gap-junctional channels (connexin oligomers) are large-diameter aqueous pores formed by head-to-head association of two gap-junctional hemichannels, one from each of the adjacent cells. Profound hearing loss of genetic origin is common, and mutations of connexin 26 (Cx26) are the most frequent cause of this disorder. The Cx26 R75W mutant has been associated with disruption of cell-to-cell communication and profound hearing loss, but the mechanism of the gap-junctional defect is unknown. Here, we show that Cx26 R75W forms gap-junctional hemichannels that display altered voltage dependency and reduced permeability, and which cannot form functional gap-junctional channels between neighboring cells. The R75W phenotype is dominant at the gap-junction channel but not at the hemichannel level. Therefore, the absence of gap-junctional communication caused by R75W expression is due to defective gap-junction formation by functional hemichannels.

Animals↗

PubMed2005

Omeprazole delays gastric emptying in healthy volunteers: an effect prevented by tegaserod.

BACKGROUND: Proton-pump inhibitors effectively suppress stomach acidity. They are widely used for treating gastro-oesophageal reflux disease and related conditions. While generally safe, omeprazole and other proton-pump inhibitors can delay gastric emptying. AIM: To test the hypothesis that tegaserod can normalize or prevent omeprazole-induced delay in gastric emptying. METHODS: This was a randomized, double-blind, placebo-controlled, parallel group study in 40 healthy male volunteers. After informed consent and screening, qualified volunteers were treated with unblinded omeprazole 20 mg b.d. and either blinded tegaserod 6 mg t.d.s. (active treatment group) or placebo-matching tegaserod t.d.s. (control group) for 14 days. Gastric emptying was assessed before and after treatment, using a scintigraphy method. RESULTS: Omeprazole monotherapy significantly delayed gastric emptying expressed by duration of lag-phase (P < 0.007), time to gastric half-emptying (P < 0.003), and gastric retention of the meal at 60 (P < 0.002) and 120 min (P < 0.04) after its ingestion. Tegaserod taken together with omeprazole effectively prevented development of the above effects. Combined treatment was safe and well tolerated. CONCLUSION: Concomitant administration of tegaserod 6 mg t.d.s. prevented development of the delayed gastric emptying induced by omeprazole monotherapy.

Adolescent↗

PubMed2005

Phase effects in the diffraction of light: beyond the grating equation.

Diffraction gratings affect the absolute phase of light in a way that is not obvious from the usual derivation of optical paths using the grating equation. For example, consider light which encounters first one and then the second of two parallel gratings. If one grating is moved parallel to its surface, the phase of the light diffracted from the grating pair is shifted by 2pi each time the grating is moved by one grating constant, even though the geometric path length is not altered by the motion. This additional phase shift must be included when incorporating diffraction gratings in interferometers.

Journal Article↗

PubMed2005

Limits on gravitational-wave emission from selected pulsars using LIGO data.

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Journal Article↗

PubMed2005

Thermolabile phenotype of carnitine palmitoyltransferase II variations as a predisposing factor for influenza-associated encephalopathy.

To assess the etiology of influenza-associated encephalopathy (IAE), a surveillance effort was conducted during 2000-2003 in South-West Japan. All fatal and handicapped patients except one (4/34 patients) exhibited a disorder of mitochondrial beta-oxidation evoked by the inactivated carnitine palmitoyltransferase II (CPT II) with transiently elevated serum acylcarnitine ratios (C(16:0) + C(18:1))/C(2) > 0.09 during high-grade fever. Analyses of genotypes and allele compositions of CPT II revealed a thermolabile phenotype of compound heterozygotes for [1055T > G/F352C] and [1102G > A/V368I], which shows a higher frequency in IAE patients than healthy volunteers (P < 0.025). The thermolabile phenotype of CPT II variations may be a principal genetic background of IAE in Japanese.

Adolescent↗

PubMed2005

Open charm yields in d+Au collisions at squareroot[sNN]=200 GeV.

Midrapidity open charm spectra from direct reconstruction of D0(D0)-->K-/+pi+/- in d+Au collisions and indirect electron-positron measurements via charm semileptonic decays in p+p and d+Au collisions at squareroot[sNN]=200 GeV are reported. The D0(D0) spectrum covers a transverse momentum (pT) range of 0.1<pT<3 GeV/c, whereas the electron spectra cover a range of 1<pT<4 GeV/c. The electron spectra show approximate binary collision scaling between p+p and d+Au collisions. From these two independent analyses, the differential cross section per nucleon-nucleon binary interaction at midrapidity for open charm production from d+Au collisions at BNL RHIC is dsigma(NN)cc/dy=0.30+/-0.04(stat)+/-0.09(syst) mb. The results are compared to theoretical calculations. Implications for charmonium results in A+A collisions are discussed.

Journal Article↗

PubMed2005

Ensembl 2005.

The Ensembl (http://www.ensembl.org/) project provides a comprehensive and integrated source of annotation of large genome sequences. Over the last year the number of genomes available from the Ensembl site has increased by 7 to 16, with the addition of the six vertebrate genomes of chimpanzee, dog, cow, chicken, tetraodon and frog and the insect genome of honeybee. The majority have been annotated automatically using the Ensembl gene build system, showing its flexibility to reliably annotate a wide variety of genomes. With the increased number of vertebrate genomes, the comparative analysis provided to users has been greatly improved, with new website interfaces allowing annotation of different genomes to be directly compared. The Ensembl software system is being increasingly widely reused in different projects showing the benefits of a completely open approach to software development and distribution.

Animals↗

PubMed2005

Heat shock treatment suppresses angiotensin II-induced SP-1 and AP-1 and stimulates Oct-1 DNA-binding activity in heart.

OBJECTIVE AND DESIGN: Heat shock (HS) treatment (42 degrees C for 15 min) and the expression of heat shock proteins (Hsps) protect against angiotensin (Ang) II-induced inflammation in aorta and heart by suppressing the activation of the pro-inflammatory transcription factor NF-kappaB. In this study we examined pro-inflammatory transcription factors SP-1, AP-1 and an anti-inflammatory cytokine transcriptional repressor, Oct-1, DNA-binding activities after chronic Ang II infusion and the effect of HS treatment on these pathways in heart. METHODS: HS treatment was administered 24 hr before initiation of Ang II infusion to male Sprague-Dawley rats. Systolic blood pressure was measured by tail-cuff plethysmography, expression of heat shock proteins was monitored by Western analysis and DNA-binding activities of SP-1, AP-1 and Oct-1 were determined by electrophoretic mobility shift assay. RESULTS: Ang II infusion induced a progressive increase in systolic blood pressure that was suppressed by the heat shock treatment. Following heat shock treatment, Hsp70 and Hsp27 were expressed at elevated levels. The Ang II-induced activation of SP-1 and AP-1 were significantly suppressed by HS treatment. In addition, HS increased Oct-1 activity that was suppressed by Ang II infusion. CONCLUSION: These data suggest that heat shock suppresses inflammation by differentially regulating pro-inflammatory and anti-inflammatory cell signaling pathways.

Angiotensin II↗

PubMed2005

Latent TGF-beta binding proteins.

Latent TGF-beta binding proteins are multidomain proteins with a common, highly repetitive structural organization and partially overlapping expression patterns. Latent TGF-beta binding protein-1, -3 and -4 bind latent TGF-beta. TGF-betas are normally secreted as latent complexes, consisting of the mature TGF-beta dimer non-covalently bound to its processed propeptide dimer plus a latent TGF-beta binding protein. The latent TGF-beta binding protein is covalently bound to the propeptide. These binding proteins may perform at least two functions: structural, as components of the matrix, and regulatory, as modulators of TGF-beta availability.

Animals↗