Biomedical subjects

Dong Yang

Publications and source records attributed to Dong Yang.

30 records · Page 2Linked to original sources

PubMed2004

Changes in the T-cell receptor V beta gene repertoire after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: We distinguished graft-versus-host disease (GVHD) from graft-versus-leukemia (GVL) effects and to investigate the distribution of T-cell receptor (TCR) V beta gene repertoire in individuals with leukemia before and after allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: Peripheral blood mononuclear cells (PBMC) were obtained from 10 normal individuals, 8 donors and 11 patients with leukemia before and after transplantation. Polymerase chain reaction (PCR) amplification of complementarity-determining region 3 (CDR3) of 24 TCR V beta genes was used to examine serial samples of PBMC. The PCR products were further analyzed by genescan to evaluate clonality of T cells. RESULTS: The 24 TCR V beta gene repertoire displayed highly diverse and polyclonal spectratypes in all normal individuals and 4 of 8 donors. Another 4 donors expressed part of the 24 TCR V beta subfamily and 1 donor had oligoclonality. The expressions of the 24 TCR V beta subfamilies were skewed and restricted in 11 leukemia patients before and after transplantation. Some absences of 24 TCR V beta subfamily expression were quite similar between the recipients pro-transplantation and related donors. The number of subfamilies expressed increased over time post-transplantation, but the restricted expressions of the subfamily could last 6 - 30 months after transplantation. All patients with GVHD and some without GVHD exhibited T cell clonal expansion. The expansive T cell clone was distributed in V beta 2-3, 16-17, 18-19, 21 and V beta 23 in patients with GVHD and in V beta 7, 9, 16 and 19 in patients without GVHD. One patient with syngeneic-HSCT (syn-HSCT) had V beta 15 and 16 T cell expansion after transplantation. One patient displayed V beta 18 T cell expansion after donor lymphocyte infusion (DLI). CONCLUSIONS: Normal individuals express the entire 24 TCR V beta gene repertoire and have polyclonal distribution. However, the TCR V beta gene repertoire is only partially expressed in some donors. The TCR V beta gene repertoire is restrictedly expressed in a skew fashion in patients with leukemia before and after transplantation. The number of TCR V beta gene subfamilies increases over time post-transplantation. GVHD and GVL effects may induce the proliferation of T cell clones. Clinical GVL response may be distinguished from GVHD alloreactivity through the host MHC antigen.

Graft vs Host Disease↗

PubMed2003

Well-defined star-shaped calcite crystals formed in agarose gels.

Single crystals of calcite exhibiting a morphology of well-defined 8-armed stars, which evolved from original rhombohedral calcite crystals with their 8 points extending radially into eight arms, were produced by crystallization of CaCO3 in agarose gels.

Calcium Carbonate↗

PubMed2003

[p33(ING1) gene expression and mutation in stomach cancer tissues and precarcinomatous tissues].

OBJECTIVE: To analyze the relationship of p33(ING1) gene expression and p33(ING1) exon-2 mutation to the pathogenesis, development and consequence of stomach cancer. METHODS: Envision immunohistochemical method was utilized to detect the p33(ING1) expression in 103 specimens of stomach cancer, 36 specimens of stomach mucosal atypical hyperplasia, and 32 specimens of normal stomach mucosa. PCR-SSCP was utilized to detect p33(ING1) exon-2 mutation in stomach cancer tissues. RESULTS: The p33(ING1) expression rate in stomach cancer was 54.4% (56/103), significantly lower than that in precarcinomatous tissues (94.4%, 34/36, P < 0.01) and that in normal tissues (100%, 32/32, P < 0.01). The p33(ING1) expression in stomach cancer was related to tumor growth, distant metastasis and tumor differentiation (all P < 0.05). p33(ING1) gene exon-2 mutation was detected in 3 cases of stomach cancer tissues (12%, 3/25), and not in other tissues by PCR-SSCP method. CONCLUSION: p33(ING1) low expression, and gene p33(ING1) exon-2 mutation may play an important role in the pathogenesis, development and consequence of stomach cancer.

Adult↗

PubMed2003

Purification and characterization of Ulva pertusa Kjellm alkaline phosphatase.

The activity of alkaline phosphatase (ALP, EC 3.1.3.1.) was found in seaweeds, including five kinds of green alga, eighteen kinds of red alga, and six kinds of brown alga, collected from the seaside of Dalian in China. The enzyme was purified 1230-fold from Ulva pertusa Kjellm. It had a specific activity of 48.6 U/mg protein and was proven to be homogeneous by SDS-PAGE with a subunit molecular mass of 19.5 kDa. The activity of ALP peaked at pH9.8, and was completely inhibited by DTT and partly by NBS. The Michaelis-Menten constant Km and the maximum reaction velocity Vmax, at pH 9.8 and 37 degrees C were 0.950 mM and 5.00 microM/min, respectively.

Alkaline Phosphatase↗

PubMed2003

[Study of molybdenum (V) thiocyanate complexes in the acidic aqueous solution].

In this paper, the Mo(V)-thiocyanate complexing reaction in the acidic aqueous solution without surfactant or organic solvent was studied. It was found that the Mo(V)-thiocyanate complexes could be stable for 4 h at least in the 50 mL solution containing 7.5 mL H2SO4 (1:1), 4 mL HClO4 (1:1), 3 mg Fe2+ and 4 mL vitamin C (6%). The absorption spectrum of Mo(V)-thiocyanate complexes under this condition was studied, a peak of 460 nm was found and the maximal molar absorption coefficient was determined to be 1.02 x 10(4). The reaction mechanism of the Mo(V)-thiocyanate complexes was determined to be a three-grade complexing reaction by using the equilibrium movement method. Meanwhile, the stable constants of all kinds of grades complexes was determined by the [symbol: see text] method to be beta 1 = 15.63, beta 2 = 174.4 and beta 3 = 1,502, and the corresponding molar absorption coefficients were delta epsilon 1 = 8,957, delta epsilon 2 = 9,347 and delta epsilon 3 = 10,610, respectively.

Chelating Agents↗

PubMed2002

Preparation, characterization, and tabletting properties of a new cellulose-based pharmaceutical aid.

A new cellulose-based tabletting excipient, hereinafter referred to as UICEL, has been developed by treating cellulose powder with an aqueous solution of sodium hydroxide (conc. > or = 5N) and subsequently precipitating it with ethyl alcohol. UICEL is similar in structure to Avicel PH-102, a commercial direct compression excipient commonly referred to as microcrystalline cellulose (MCC). It, however, shows the cellulose II lattice, while Avicel PH-102 belongs to the cellulose I polymorphic form. As produced, UICEL consisted of a mixture of aggregated and non-aggregated fibers. The degrees of polymerization (DP) and crystallinity (DC) of UICEL, determined by the viscosity and powder X-ray methods, were 189-207 and 47-58%, respectively. Avicel PH-102, by comparison, showed an aggregated structure with DP and DC values corresponding to 248 and 76.9%, respectively. Compared to Avicel PH-102, UICEL shows higher true density, bulk density, tap density, Carr's index and Hausner ratio values. The mean deformation pressure (P(y)) values calculated from the linear portion of the Heckel plots for UICEL and Avicel PH-102 were about 104 and 87 MPa, respectively, suggesting that UICEL is less ductile than Avicel PH-102. The hardness values of UICEL tablets increased nearly linearly with increasing compression pressures. Comparatively, Avicel PH-102 formed stronger tablets. Irrespective of the compression pressure used, all UICEL tablets disintegrated within 15 s, whereas Avicel PH-102 tablets of comparable strengths remained intact for over 12 h. In conclusion, the results show that UICEL can be used as a direct compression excipient, especially in the design and development of fast-disintegrating tablets.

Cellulose↗

PubMed2002

Cyclodextrin complexation: influence on the solubility, stability, and cytotoxicity of camptothecin, an antineoplastic agent.

The solubility of camptothecin (CPT), a highly potent antineoplastic agent, as a function of different concentrations of cyclodextrins (alpha-cyclodextrin, alpha-CD; beta-cyclodextrin, beta-CD; and gamma-cyclodextrin, gamma-CD; hydroxypropyl-beta-cyclodextrin, HP-beta-CD; and randomly substituted dimethyl-beta-cyclodextrin, RDM-beta-CD, and dimethyl-gamma-cyclodextrin, RDM-beta-CD) in 0.02 N HCl solution at 25 degrees C was investigated. The results showed a linear increase in the solubility of CPT with increasing concentration of CDs. The apparent stability constants (K(c)) for the CPT complexes with alpha-CD, beta-CD, gamma-CD, HP-beta-CD, RDM-beta-CD, and RDM-gamma-CD were 188, 266, 73, 160, 910, and 40.6 M(-1), respectively, suggesting that RDM-beta-CD afforded the most stable complex. At a 25% w/v concentration of RDM-beta-CD, the solubility of CPT was 228.45 +/- 8.45 microg/ml, about 171 times higher than that in 0.02 N HCl. The stability of CPT in pH 7.4 buffer at 25 degrees C also increased linearly with an increase in the concentration of RDM-beta-CD. The observed pseudo-first-order hydrolysis rate constants (k(obs)) for the free and complexed CPT were 11.8 x 10(-3) and 1.18 x 10(-3) min(-1), corresponding to an increase in half-life of CPT from 58.7 to 587.3 min, respectively. The preliminary cytotoxicity study against the human-derived myeloid THP-1 leukemia cell line showed RDM-beta-CD/CPT and HP-beta-CD/CPT complexes to be about two-fold more active than free CPT. In conclusion, the results showed that CDs, in general, and RDM-beta-CD, in particular, are effective complexing agents and can be used to improve the solubility and stability of CPT. The increase in cytotoxicity of CPT in the presence of CD is likely due to an increase in its stability.

Antineoplastic Agents, Phytogenic↗

PubMed2002

[Role of high resolution CT in diffuse pulmonary nodules].

OBJECTIVE: To evaluate high resolution CT (HRCT) in the diagnosis of diffuse pulmonary nodules. METHODS: Fifty normal chest radiographs, conventional CT and HRCT were used to evaluate the visualization of pulmonary lobule. The configuration, distribution and intrinsic structure of lesion in 38 patients with diffuse pulmonary nodules were analyzed by HRCT. RESULTS: The chest radiographs were not able to show the structure of pulmonary lobule. The visualization rates of pulmonary lobule were 20% by conventional CT and 50% by HRCT (P < 0.05). Of 38 patients with diffuse pulmonary nodules, 19 had interstitial nodules which were located in the pulmonary intestities, the lobular septa and under the pleura. HRCT could clearly show their para-bronchial distribution with clear cut margin. Four had airspace nodules, chiefly shown as solidification of the air spaces. There was no nodule beneath the pleura or in the lobular septa. HRCT revealed even density and hazzy margins. Fifteen had randomly distributed nodules, with the nodules scattered at random. HRCT showed nodules with high density, sizes varying greatly but the margin was clear. CONCLUSION: High resolution CT is able to show the pattern of distribution, intranodular structures and background of the diffuse pulmonary nodules, which is valuable in the diagnosis and differential diagnosis of this disease.

Adult↗

PubMed2002

[Spectroscopic determination of the dynamic electrical spark temperature of nonel tube igniter].

A set of transient real time two-line spectroscopy temperature measured system with quartz optical fiber was established. Two spectral lines are Cu I 510.5 and Cu I 521.8 nm respectively. Its maximum time resolution is up to 0.1 microsecond. The discharge spark temperature and spark discharge time of the nonel tube igniter under different voltage are 2,100-4,200 and 100-200 microseconds respectively. The spark discharge time increase with the rising of charge voltage. The discharge spark temperature variations versus the discharge time under different voltages, and the spark duration under different discharge conditions were studied with this instrument.

English Abstract↗

PubMed2001

Structure of the Methanococcus jannaschii mevalonate kinase, a member of the GHMP kinase superfamily.

The mevalonate-dependent pathway is used by many organisms to synthesize isopentenyl pyrophosphate, the building block for the biosynthesis of many biologically important compounds, including farnesyl pyrophosphate, dolichol, and many sterols. Mevalonate kinase (MVK) catalyzes a critical phosphoryl transfer step, producing mevalonate 5'-phosphate. The crystal structure of thermostable MVK from Methanococcus jannaschii has been determined at 2.4 A, revealing an overall fold similar to the homoserine kinase from M. jannaschii. In addition, the enzyme shows structural similarity with mevalonate 5-diphosphate decarboxylase and domain IV of elongation factor G. The active site of MVK is in the cleft between its N- and C-terminal domains. Several structural motifs conserved among species, including a phosphate-binding loop, have been found in this cavity. Asp(155), an invariant residue among MVK sequences, is located close to the putative phosphate-binding site and has been assumed to play the catalytic role. Analysis of the MVK model in the context of the other members of the GHMP kinase family offers the opportunity to understand both the mechanism of these enzymes and the structural details that may lead to the design of novel drugs.

Amino Acid Sequence↗

PubMedDate not supplied

Synthesis and efficiency of a spherical macroporous epoxy-polyamide chelating resin for preconcentrating and separating trace noble metal ions.

The determination of noble metals in various materials usually requires their preconcentration and separation from other elements. In spite of the improvements in analytical instrumentation and the development of new analytical techniques such as ICP-MS, which are capable of detecting metal ions at ppt levels, the interference caused by the sample matrix still exists and is perhaps the most serious problem, making a pre-determination enrichment step necessary. Thus, the search for efficient preconcentration and separation methods is essential. A series of chelating resins that can selectively adsorb noble metal ions from aqueous solutions have been described. Functional groups, such as salicylaldoxime and thiosemicarbazide have been incorporated in cross-linked polymers or porous silica gel. These resins have very high selectivity for one or several types of noble metal ion. However, desorption of noble metals from these resins is usually difficult. Hence, the development of an adsorbent from which noble metals can be easily desorbed is needed. In this paper, a new spherical macroporous epoxy-polyamide chelating resin that met this requirement was synthesized by one step reaction. The synthesis of the resin was safe, rapid and more simple and economical than many report adsorbents. Meanwhile, the resin showed more advantages: better acid and alkali resistance; higher adsorption capacity and lower preconcentration concentrations. A resin column procedure combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of trace Rh(III), Ru(III) and Ir(IV) in real samples was established.

Chelating Agents↗

PubMedDate not supplied

Approach for workflow modeling using pi-calculus.

As a variant of process algebra, Pi-calculus can describe the interactions between evolving processes. By modeling activity as a process interacting with other processes through ports, this paper presents a new approach: representing workflow models using Pi-calculus. As a result, the model can characterize the dynamic behaviors of the workflow process in terms of the LTS (Labeled Transition Semantics) semantics of Pi-calculus. The main advantage of the workflow model's formal semantic is that it allows for verification of the model's properties, such as deadlock-free and normal termination. Moreover, the equivalence of workflow models can be checked through weak bisimulation theorem in the Pi-calculus, thus facilitating the optimization of business processes.

Decision Support Techniques↗