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X He

Publications and source records attributed to X He.

At least 37 records · Page 2Linked to original sources
PubMed2004

Observation of the decay psi(2S)-->K0SK0L.

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Journal Article↗
PubMed2004

Determination of procarbazine in human plasma by liquid chromatography with electrospray ionization mass spectrometry.

Procarbazine is a cytotoxic chemotherapeutic agent used in the treatment of lymphomas and brain tumors. Its pharmacokinetic behavior remains poorly understood even though more than 30 years have elapsed since the drug was approved for clinical use. To characterize the pharmacokinetics of procarbazine in brain cancer patients during a phase I trial, a method for determining the drug in human plasma by reversed-phase high-performance liquid chromatography (HPLC) with electrospray ionization mass spectrometry (ESI-MS) was developed and thoroughly validated. Plasma samples were prepared for analysis by precipitating proteins with trichloroacetic acid and washing the protein-free supernatant with methyl tert-butyl ether to remove excess acid. The solution was separated on a Luna C-18 analytical column using methanol-25 mM ammonium acetate buffer, pH 5.1 (22:78, v/v) as the mobile phase at 1.0 ml/min. A single-quadrupole mass spectrometer with an electrospray interface was operated in the selected-ion monitoring mode to detect the [M+H](+) ions at m/z 222.2 for procarbazine and at m/z 192.1 for the internal standard (3-dimethylamino-2-methylpropiophenone). Procarbazine and the internal standard eluted as sharp, symmetrical peaks with retention times (mean+/-S.D.) of 6.3+/-0.1 and 9.9+/-0.3 min, respectively. Calibration curves of procarbazine hydrochloride in human plasma at concentrations ranging from 0.5 to 50 ng/ml exhibited excellent linearity. The mean absolute recovery of the drug from plasma was 102.9+/-1.0%. Using a sample volume of 150 microl, procarbazine was determined at the 0.5 ng/ml (1.9 nM) lower limit of quantitation with a mean accuracy of 105.2% and an interday precision of 3.60% R.S.D. on 11 different days over 5 weeks. During this same time interval, the between-day accuracy for determining quality control solutions of the drug in plasma at concentrations of 2.0, 15 and 40 ng/ml ranged from 97.5 to 98.2% (mean+/-S.D., 97.9+/-0.4%) and the precision was 3.8-6.2% (mean+/-S.D., 5.1+/-1.2%). Stability characteristics of the drug were thoroughly evaluated to establish appropriate conditions to process, store and prepare clinical specimens for chromatographic analysis without inducing significant chemical degradation. The sensitivity achieved with this assay permitted the plasma concentration-time profile of the parent drug to be accurately defined following oral administration of standard doses to brain cancer patients.

Antineoplastic Agents↗
PubMed2004

Variable cyclosporine exposure: a risk factor for chronic allograft nephropathy and graft loss?

BACKGROUND: Following the introduction of ciclosporine (CsA), the 2-year survival of transplanted kidneys improved from less than 60% to over 80%. Though the introduction of this drug resulted in a marked improvement in graft survival, its use was not without problems. Variable absorption and a narrow therapeutic index resulted in the need for measurements of CsA blood concentrations to tailor the drug dose to maximize therapeutic efficacy while minimizing toxicity. METHODS: Data were available from the LOTESS study of 4948 transplant patients receiving Neoral with at least 5 years' follow-up. Potential risk factors associated with outcome in renal transplant recipients treated with CsA were explored: the primary outcome variable was graft loss. A stepwise binary logistic regression analysis was used to identify donor, recipient, and treatment variables related to outcome. RESULTS: In the initial analysis, chronic rejection was the only significant predictor of graft loss. The relative risk (RR) of graft loss was 16.9 (95% CI = 13.9-20.4). Further analysis identified four independent risk factors for chronic rejection cadaveric donor (RR, 1.50; 95% CI = 1.05-2.15), older donor (RR, 1.02; 95% CI = 1.01-1.02), younger recipient (RR, 1.02; 95% CI = 1.02-1.03), and variable predose CsA concentration (RR, 1.25; 95% CI = 1.06-1.48). CONCLUSION: With the UK kidney transplant waiting list at about 5000 patients and only 1658 transplants performed during 2002, it is important maximize graft survival. For example, perhaps marginal donors (age > 55) can be matched to older recipients without increasing the risk of chronic allograft nephropathy and therefore graft loss. Variable predose CsA concentrations may arise from at least three different sources: adherence to treatment, drug formulation, and individual variation in absorption. Therefore, it is important to emphaze to patients that erratic compliance may increase their risk of graft loss. Second, although only one CsA formulation is marketed in the UK, when generic forms of CsA are introduced it will be important to demonstrate consistent delivery of CsA from these new formulations. Third, improved monitoring of CsA using a C2 rather than a predose blood concentration measurement may be used to reduce intra-individual variations in drug exposure.

Adult↗
PubMed2004

Prospective study of relationship between cytomegalovirus pneumonia and viral load in renal transplant recipients.

The present study prospectively examined the relationship between cytomegalovirus interstitial pneumonia (CMV-IP) and viral load among 56 renal transplant recipients. We sought to identify the cutoff of viral load to predict CMV-IP. Blood samples were obtained weekly within the first 2 months and every second week during 2 to 6 months after kidney transplantations. A commercial real-time polymerase chain reaction (PCR)-method was applied to quantify CMV-DNA in plasma or in leukocytes. Among 54 renal transplant recipients who were analyzed for CMV-DNA in the blood (96.4%), 8 experienced CMV-IP (14.3%) and 2 died (3.6%). After kidney transplantation, CMV-DNA loads were near 0 in plasma before the week 4 and before the week 3 in leukocytes among both groups. From week 5 (week 4, in leukocytes), plasma CMV-DNA loads in the CMV-IP group increased, the peak value reached at week 8 in plasma and the week 9 in leukocytes. Whereas, the CMV-DNA loads both in plasma and in leukocytes in the non-CMV-IP group fluctuated at lower levels, those in plasma were significantly different between the 2 groups at the weeks 5, 7, and 9. For CMV-DNA in leukocytes, there were significant differences between 2 groups from week 6 to week 11. The present study demonstrated that dynamic determination of CMV-DNA may predict the occurrence of CMV-IP. Viral loads over 10(4) copies/mL plasma continuing for 3 weeks may serve as a cutoff to predict CMV-IP.

Cytomegalovirus↗
PubMed2004

Early acute rejection does not affect chronic allograft nephropathy and death censored graft failure.

BACKGROUND: Even with the development of modern immunosuppression, an acute rejection episode is a major complication after renal transplantation. Acute rejection episodes have been used as clinical indicators for chronic allograft nephropathy and graft loss. We investigated the timing and frequency of acute rejection episodes in relation to long-term graft survival and chronic allograft nephropathy. METHODS: The Long Term Efficacy and Safety Surveillance study of transplant patients receiving cyclosporin (Neoral) included 1706 adult renal transplants (1995 to 2003) with a functioning graft for at least 1 year. The impact on death-censored long-term graft survival was evaluated for acute rejection episodes (single or multiple) within 3 months, at 3 to 6 months, at 6 to 12 months, or at over 1 year posttransplant. A stepwise binary logistic regression was employed to identify independent risk factors for the time to occurrence of an acute rejection episode. RESULTS: An acute rejection episode occurring within 3 months posttransplantation had no effect on either death-censored long-term graft failure (P=.2157) or chronic allograft nephropathy (P=.9331). However, an acute rejection episode occurring at 1 year or later posttransplantation was significantly associated with death censored long-term graft failure (P <.0001) and chronic allograft nephropathy (P <.0001). The numbers of HLA-DR mismatches and younger recipient ages were independent risk factors for early acute rejection. CONCLUSION: Among patients whose graft survives at least 12 months, an early acute rejection episode within 3 months posttransplant was not associated with either death-censored long-term graft survival or chronic allograft nephropathy among adults treated with cyclosporin. However, an acute rejection episode occurring at 1 year or later posttransplantation showed a positive association with death-censored long-term graft survival or chronic allograft nephropathy. Lower numbers of HLA-DR mismatches sum to reduce the occurrence of acute rejection and the hospitalization time.

Acute Disease↗
PubMed2004

Investigation of the thermal and tissue injury behaviour in microwave thermal therapy using a porcine kidney model.

Minimally invasive microwave thermal therapies are being developed for the treatment of small renal cell carcinomas (RCC, d<3 cm). This study assessed the thermal history and corresponding tissue injury patterns resulting from microwave treatment of the porcine renal cortex. Three groups of kidneys were evaluated: (1) in vitro treated, (2) in vivo with 2-h post-treatment perfusion (acute) and (3) in vivo with 7-day post-treatment perfusion (chronic). The kidneys were treated with an interstitial water-cooled microwave probe (Urologix, Plymouth, MN) that created a lesion centered in the renal cortex (50 W for 10 min). The thermal histories were recorded at 0.5 cm radial intervals from the probe axis for correlation with the histologic cellular and vascular injury. The kidneys showed a reproducible 2 cm chronic lesion with distinct histologic injury zones identified. The thermal histories at the edge of these zones were found using Lagrangian interpolation. The threshold thermal histories for microvascular injury and stasis appeared to be lower than that for renal epithelial cell injury. The Arrhenius kinetic injury models were fit to the thermal histories and injury data to determine the kinetic parameters (i.e. activation energy and frequency factor) for the thermal injury processes. The resultant activation energies are consistent in magnitude with those for thermally induced protein denaturation. A 3-D finite element thermal model based on the Pennes bioheat equation was developed and solved using ANSYS (V7.0). The real geometry of the kidneys studied and temperature dependent thermal properties were used in this model. The specific absorption rate (SAR) of the microwave probe required for the thermal modelling was experimentally determined. The results from the thermal modelling suggest that the complicated change of local renal blood perfusion with temperature and time during microwave thermal therapy can be predicted, although a first order kinetic model may be insufficient to capture blood flow changes. The local blood perfusion was found to be a complicated function of temperature and time. A non-linear model based on the degree of vascular stasis was introduced to predict the blood perfusion. In conclusion, interstitial microwave thermal therapy in the normal porcine kidney results in predictable thermal and tissue injury behaviour. Future work in human kidney tissue will be necessary to confirm the clinical significance of these results.

Algorithms↗
PubMed2004

Elicitation of both CD4 and CD8 T-cell-mediated specific immune responses to HCA587 protein by autologous dendritic cells.

We recently cloned a new member of cancer/testis antigen named HCA587, which was highly expressed in human hepatocellular carcinoma (HCC) tissues. To investigate it as a potential tumour-specific target for immunotherapy, the immunogenicity of this protein, especially the ability to induce specific cellular immune responses, was evaluated in the present study. As dendritic cells (DC) are the most potent antigen-presenting cells, DC-based vaccination has recently shown marked promise for the treatment of human malignancies by immunological intervention. Here, we demonstrate that autologous DC loaded with HCA587 protein could induce specific T-cell responses in healthy individuals by in vitro stimulations. Enzyme-linked immunospot analysis for interferon-gamma (IFN-gamma) secretion demonstrated HCA587-specific CD8(+) T cells in the antigen-stimulated peripheral blood lymphocytes, and the analysis of CD4(+) T cells by proliferation assay also showed antigen-specific reactivities in normal donors. Two-colour flow cytometric analysis of surface markers and intracellular cytokine expression demonstrated that HCA587-specific cytotoxic T lymphocytes exhibited a heterogeneous CD8(+)/CD56(+) expression, and a striking T-helper 1 cytokine bias (IFN-gamma(high)/IL-4(low)) was observed for both CD4(+) and CD8(+) HCA587-specific lymphocyte populations. We conclude that HCA587 is a potent immunogen that can induce CD4(+) and CD8(+) T-cell-mediated specific immune responses, and these findings propose HCA587 as a good candidate for the development of a therapeutic protein-based DC tumour vaccine for the treatment of HCC patients.

Antigens, Neoplasm↗
PubMed2004

Identification of a novel HLA-F allele - HLA-F*010102.

We describe herein the identification of HLA-F*010102 by cloning the full-length coding sequence with reverse-transcription polymerase chain reaction (RT-PCR). This new allele was found in two Han Chinese individuals in the course of cloning major histocompatibility complex class Ib (MHC Ib) cDNA. It was identical to HLA-F*010101 except for a single-nucleotide substitution in codon -1 (GCG --> GCA). This nucleotide change represents a synonymous mutation, as both triplets code for an alanine. The cDNA of this allele was 48 bp shorter than HLA-F*010101 due to splicing out exon 7. Analysis of the deduced amino acid sequence revealed that the product of this new allele had the identical extracellular domain and transmembrane region but had a shorter cytoplasmic tail.

Alleles↗
PubMed2004

Construction and selection of human anti-idiotypic antibody single chain variable fragments or CDR3 fragments of nasopharyngeal carcinoma.

Peripheral blood mononuclear cells (PBMCs) of patients with NPC were immunized in vitro by anti-NPC monoclonal antibody FC2 and transformed by Epstein-Barr virus (EBV). Detection showed that of 10 NPC patients, 8 patients' B cells immunized by FC2 and transformed by EBV produced anti-idiotypic antibodies to NPC. Five types of VH genes and 7 types of VL genes were obtained by RT-PCR amplification and then connected with (Gly4Ser)3 linker to form 14 types of scFv genes. ScFv genes digested with Sfi I were cloned into vector fUSE5 and transformed into E. coli MC 1061. Phage anti-idiotypic antibody library with 1.5 x 10(8) clones was obtained. After four rounds of panning, 270 phage clones were selected randomly and 91 FC2-positive clones were obtained by Sandwich ELISA, the positive ratio was 33.7%. 5 clones (D83, E92, G22, I50, I54), which might display beta type Ab2 scFv, were selected by binding inhibition test. These 5 phage anti-idiotypic antibodies were further analyzed by DNA sequencing. The VDJ regions of G22, I50, I54 belonged to VH4-39-D4-11-JH3-linker-V1-19-JL2, VH4-4-D4-11-JH6 and VH4-31-D4-11-JH6, respectively. E92 had the same VDJ regions with G22; D83 had the same VDJ regions with 150. So, a strategy for preparing and selecting beta type Ab2 scFv or CDR by means of immunization in vitro, EBV transformation and phage display technique is feasible, which paves a way for preparing cancer vaccine using beta type Ab2 scFv.

Animals↗
PubMed2003

Elliptic flow of identified hadrons in Au+Au collisions at sqrt sNN =200 GeV.

The anisotropy parameter (v(2)), the second harmonic of the azimuthal particle distribution, has been measured with the PHENIX detector in Au+Au collisions at sqrt[s(NN)]=200 GeV for identified and inclusive charged particle production at central rapidities (|eta|<0.35) with respect to the reaction plane defined at high rapidities (|eta|=3-4 ). We observe that the v(2) of mesons falls below that of (anti)baryons for p(T)>2 GeV/c, in marked contrast to the predictions of a hydrodynamical model. A quark-coalescence model is also investigated.

Journal Article↗
PubMed2003

Scaling properties of proton and antiproton production in sqrt[s(NN)]=200 GeV Au+Au collisions.

We report on the yield of protons and antiprotons, as a function of centrality and transverse momentum, in Au+Au collisions at sqrt[s(NN)]=200 GeV measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider. In central collisions at intermediate transverse momenta (1.5<p(T)<4.5 GeV/c) a significant fraction of all produced particles are protons and antiprotons. They show a centrality-scaling behavior different from that of pions. The pmacr;/pi and p/pi ratios are enhanced compared to peripheral Au+Au, p+p, and e(+)e(-) collisions. This enhancement is limited to p(T)<5 GeV/c as deduced from the ratio of charged hadrons to pi(0) measured in the range 1.5<p(T)<9 GeV/c.

Journal Article↗
PubMed2003

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays.

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Journal Article↗
PubMed2003

Vibrationally resolved photoabsorption spectroscopy of red fluorescent protein chromophore anions.

Photoabsorption studies of red fluorescent protein chromophore anions have been performed at the ELISA electrostatic heavy-ion storage ring. The broad absorption band due to electronic excitation of the chromophores is tuned to a longer wavelength (redshifted) by extending the electronic conjugation of the molecule. A clear vibrational progression is resolved with E(vib) approximately 380 and 520 cm(-1) for two different forms of the chromophore. The vibrational modes correspond to collective motions of the entire molecular structure. It is argued that the excited electronic state has an equilibrium configuration far from that of the electronic ground state, i.e., poor Franck Condon overlap.

Absorption↗
PubMed2003

Mapping quantitative trait loci underlying triploid endosperm traits.

Endosperm, which is derived from two polar nuclei fusing with one sperm, is a triploid tissue in cereals. Endosperm tissue determines the grain quality of cereals. Improving grain quality is one of the important breeding objectives in cereals. However, current statistical methods for mapping quantitative trait loci (QTL) under diploid genetic control have not been effective for dealing with endosperm traits because of the complexity of their triploid inheritance. In this paper, we derive for the first time the conditional probabilities of F(3) endosperm QTL genotypes given different flanking marker genotypes in F(2) plants. Using these probabilities, we develop a multiple linear regression method implemented via the iteratively reweighted least-squares (IRWLS) algorithm and a maximum likelihood method (ML) implemented via the expectation-maximization (EM) algorithm to map QTL underlying endosperm traits. We use the mean value of endosperm traits of F(3) seeds as the dependent variable and the expectations of genotypic indicators for additive and dominance effect of a putative QTL flanked by a pair of markers as independent variables for IRWLS mapping. However, if an endosperm trait is measured quantitatively using a single endosperm sample, the ML mapping method can be used to separate the two dominance effects. Efficiency of the methods is verified through extensive Monte Carlo simulation studies. Results of simulation show that the proposed methods provide accurate estimates of both the QTL effects and locations with very high statistical power. With these methods, we are now ready to map endosperm traits, as we can for regular quantitative trait under diploid control.

Chromosome Mapping↗
PubMed2002

Flow measurements via two-particle azimuthal correlations in Au + Au collisions at sqrt [s(NN)]=130 GeV.

Two-particle azimuthal correlation functions are presented for charged hadrons produced in Au+Au collisions at the Relativistic Heavy Ion Collider (sqrt [s(NN)]=130 GeV). The measurements permit determination of elliptic flow without event-by-event estimation of the reaction plane. The extracted elliptic flow values (v2) show significant sensitivity to both the collision centrality and the transverse momenta of emitted hadrons, suggesting rapid thermalization and relatively strong velocity fields. When scaled by the eccentricity of the collision zone epsilon, the scaled elliptic flow shows little or no dependence on centrality for charged hadrons with relatively low p(T). A breakdown of this epsilon scaling is observed for charged hadrons with pT >1.0 GeV/c.

Journal Article↗
PubMed2002

Measurement of Lambda and Lambda(macro) particles in Au+Au collisions at the square root of S(NN) = 130 GeV.

We present results on the measurement of Lambda and Lambda(macro) production in Au+Au collisions at square root of (S (NN) = 130 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. The transverse momentum spectra were measured for minimum bias and for the 5% most central events. The Lambda;/Lambda ratios are constant as a function of p(T) and the number of participants. The measured net Lambda density is significantly larger than predicted by models based on hadronic strings (e.g., HIJING) but in approximate agreement with models which include the gluon-junction mechanism.

Journal Article↗
PubMed2002

Net charge fluctuations in Au + Au interactions at sqrt[s(NN)]=130 GeV.

Data from Au + Au interactions at sqrt[s(NN)]=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.

Journal Article↗