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Biomedical subjects

P Yang

Publications and source records attributed to P Yang.

At least 253 records · Page 14Linked to original sources
PubMed1997

[Cloning of the NS1 gene of dengue-2 virus and determination of its partial nucleotide sequence].

In this study, RT-PCR product of the NS1 gene of dengue-2 virus isolated in China was inserted into the DNA of T-vector plasmid. DNAs of the positive clones, which were identified by using the blue/white spot and PCR, were digested with enzymes, indicating that the inserted fragments were the same sizes as those of the amplified NS1 genes. The result of the nucleotide sequence determined by dideoxy chain-termination method indicated that 5'-terminal nucleotide sequence of the amplified NS1 fragment was not changed.

Cloning, Molecular↗
PubMed1997

[Colony-stimulating activities of serum from patients with severe aplastic anemia].

OBJECTIVE: To investigate the correlation between colony-stimulating activities of serum from patients with severe aplastic anemia (SAA) and their responses to immunosuppressive therapy (IST). METHODS: In vitro effects of sera from SAA patients before and after IST and from normal subjects on human marrow colony growth were examined in a semisolid methylcellulose culture system for burst promoting activity (BPA) and granulocyte/macrophage colony-stimulating activity (GM-CSA). Serum erythropoietin (Epo) level was also measured by ELISA method before and after IST in SAA patients. RESULTS: Serum BPAs in SAA patients at diagnosis were significantly higher than that in normal controls (P<0.001), but serum GM-CSAs in 13 of 22 SAA patients were normal,and in 9 of 22 extremely low as compared with normal values. After IST, serum BPA and GM-CSA in SAA patients had no changes. Serum Epo levels in SAA patients at diagnosis were significantly higher than that in normal controls (P<0.001). After IST,serum Epo levels declined in responded patients, while further increased in nonresponded. CONCLUSION: Serum GM-CSA of SAA patients was a predictive factor for responsiveness to IST, and a normal value was associated with a good response.

Anemia, Aplastic↗
PubMed1997

[Determination of Ni, Al, Mn and Si in copper based alloy by high current and microsecond pulsed glow discharge optical emission spectrometry].

The determination of Ni, Al, Mn and Si in copper based alloy by high current and microsecond pulsed (HCMSP) glow discharge optical emission spectrometry (GD-OES) has been reported. With the laboratory built experiment set-up, the factors effecting analytical performance have been studied. The results of sample analysis are in good agreements with the recommendation values, and the stansard deviation for six determinations were 2.66% for Ni, 2.17% for Mn, 6.02% for Si, 1.00% for Al respectively.

English Abstract↗
PubMed1997

[Enhanced emission spectra of Yb, Eu, Y and Sm HCLS with high current microsecond pulsed supply].

The emission spectra of Yb, Eu, Y, Sm hollow cathode lamps have been investigated with a high current microsecond pulsed (HCMP) supply developed in our laboratory. Both atomic and ionic emission lines of interest of these rare earth elements are enhanced by tens to tens of thousand times in HCMP mode compared to DC mode. Effects of parameters of the supply on emission intensities are surveyed. HCMP HCLs may be used as an economic and convenient excitation source for atomic/ionic fluorescence spectrometric analysis.

English Abstract↗
PubMed1997

[Study on atomic emission spectrum and spectral interferences of rare earth elements with a high resolution inductively coupled plasma atomic emission spectrometer.--II. Spectral intererences of Samarium matrix].

The rare earth elements play a very important role in today's manufacture and life. For their complex spectra it is difficult to determine the trace elements in rare earth element matrix. This work investigated the spectral interferences of samarium matrix on other rare earth elements with a high resolution inductively coupled plasma atomic emission spectrometer. A lots of spectrum information and spectral interferences were obtained, which are quite useful in the selection of analytical lines that free of spectral interferences and the elimination of the concomitant's interferences.

English Abstract↗
PubMed1997

[Progress in determination of rare earths by atomic/ionic fluorescence spectrometry].

The progress of determination of rare earths by atomic/ionic fluorescence spectrometry is reviewed. The experimental systems and the analytical characteristics of the technique are briefly discussed, and its applications are illustrated in detail. The research trends are predicted as well. The systems with appropriate combinations of excitation sources and atomization/ionization cells are well proved to increase analytical sensitivity and minimize interferences. For the excitation soures, hollow cathode lamp has been proved to be economic and practical, although pulsed dye laser has been intensively investigated. The inductively oupled plasma is a preferable atomization/ionization cell. The atomic/ionic fluorescene spectrometry is one of effective techniques for the determination of rare earths mainly due to its low spectral interference and wide linear dynamic range.

English Abstract↗
PubMed1997

CD34 expression by inflammatory fibroid polyps of the stomach.

The phenotype of the proliferated spindled cells and the histogenesis of inflammatory fibroid polyp (IFP) have been a matter of debate. To clarify the immunohistochemical profile of the main cellular component, we reviewed histologically and studied immunohistochemically 11 cases (12 lesions) of IFP of the stomach. The lesions ranged in size from 0.4 to 3.0 cm (mean, 1.0 cm). All of the IFPs occurred in the antrum. Seven cases (63.6%) were accompanied by carcinoma or adenoma, which in two cases was present in covering epithelium. Grossly, eight IFPs were sessile, and four were polypoid. Microscopically, seven (58.3%) occupied both the mucosa and submucosa. Four (33.3%) were confined to the mucosa, and one was localized only in the submucosa. They were characterized by proliferation of relatively uniform spindled cells, often in a whorl-like arrangement around the blood vessels and glands. Eosinophilic and lymphocytic infiltration of varying degree was always present. The spindled cells in all of the IFPs were diffusely immunoreactive for vimentin and CD34. Seven (58.3%) were focally positive for histiocytic markers, such as KP1 and HAM56. Three (25%) showed focal immunoreactivity for alpha smooth muscle actin. Cytokeratin, desmin, S100 protein, Factor VIII RAG, and Ki-67 were negative in these spindled cells. The principle proliferating cells in IFPs in this study showed variable degrees of histiocytic and myofibroblastic lines of differentiation. Under the influence of some etiologic factors, the primitive, uncommitted spindled mesenchymal cells exhibiting CD34 immunoreactivity around the blood vessels and glands in the lower portion of mucosa and submucosa might play a role in development of IFP.

Actins↗
PubMed1996

The highly conserved skb1 gene encodes a protein that interacts with Shk1, a fission yeast Ste20/PAK homolog.

The Shk1 protein kinase, a homolog of Saccharomyces cerevisiae Ste20 and mammalian p21Cdc42/Rac-activated kinases, is an essential component of a Ras- and Cdc42-dependent signaling cascade required for cell viability, normal morphology, and mitogen-activated protein kinase-mediated sexual responses in the fission yeast, Schizosaccharomyces pombe. To identify S. pombe proteins that modulate or mediate Shk1 functions, we conducted a two-hybrid screen for Shk1-interacting proteins. One of the genes identified as a result of this screen was skb1. We show that Skb1 interacts with a region of the N-terminal regulatory domain of Shk1 distinct from that to which Cdc42 binds, and that Shk1, Cdc42, and Skb1 are able to form a ternary complex in vivo. S.pombe cells carrying an skb1 null mutation are less elongate in morphology than wild-type cells and exhibit a moderate growth defect. The morphology defect of the skb1 deletion mutant is suppressed by overexpression of Shk1. Overexpression of Skb1 causes wild-type S. pombe cells to become hyperelongated. Additional genetic analyses described herein suggest that Skb1 is a component of the morphology control branch of the Ras signaling cascade in S. pombe and that it positively modulates Shk1 function. Homologs of Skb1 are encoded by open reading frames in the genomes of S. cerevisiae and Caenorhabditis elegans and by an uncharacterized human cDNA sequence. Thus, skb1 may be the first well-characterized member of a highly conserved family of genes encoding potential p21Cdc42/Rac-activated kinase regulators.

Amino Acid Sequence↗
PubMed1996

Diorganotin(IV) antitumor agent. (C2H5)2SnCl2 (phen)/nucleotides aqueous and solid-state coordination chemistry and its DNA binding studies.

This contribution reports a solution and solid-state study of the aqueous nucleotide coordination chemistry of the diethyltin(IV) antitumor agent, (C2H5)2SnCl2(phen). [trans-en2Os(eta-H2)] (CF3SO3)2, a versatile 1H NMR probe for biomolecules, is first used to investigate the interaction of (C2H5)2SnCl2(phen) with DGMP in neutral aqueous solution, and then the synthesis of mixed-ligands complexes formulated as (C2H5)2SnCl(phen)(Nu) (Nu is nucleotide) by reactions of (C2H5)2SnCl2(phen) with equimolar nucleotides under biologically relevant conditions is described. The new complexes were characterized by 500 MHz 1H, 31P NMR spectra; these spectroscopic data suggest that one of cis-chloro atoms in (C2H5)2SnCl2(phen) is substituted by nucleotide, and that Sn(IV) is directly coordinated to the phosphate group of the nucleotide. No evidence was found for the coordination via donor atoms of the base. On the basis of the above model studies, absorbance, fluorescence and cyclic voltammetric methods, viscosity determination, as well as agrose gel electrophoresis of superhelical pBR322 plasmid DNA were used to study the interaction of (C2H5)2SnCl2(phen) with DNA. The results indicate that (C2H5)2SnCl2(phen) binds to DNA by double modes. The drug first reacts electrostatically with the sugar-phosphate backbone of DNA; this results in changes of DNA conformation, and then phen ligand can intercalate into double-helix DNA and cause unwinding of the DNA.

Antineoplastic Agents↗
PubMed1996

Familial risk of lung cancer among nonsmokers and their relatives.

The role of family history of lung cancer in predicting lung cancer risk among nonsmokers and their relatives was evaluated in a population-based family study conducted in metropolitan Detroit. Lung cancer risk factor data were collected through telephone interviews with 257 nonsmoking lung cancer cases 40-84 years of age diagnosed between 1984 and 1987, their 2,252 relatives, 277 nonsmoking controls, and their 2,408 relatives. Lung cancer in a first-degree relative was associated with a 7.2-fold (95% confidence interval 1.3-39.7) increased risk of lung cancer among nonsmokers in the 40- to 59-year-old age group. This significant increased risk remained after adjustment for the smoking, occupational, and medical history of each family member (relative risk = 6.1, 95% confidence interval 1.1-33.4). Offspring of nonsmoking cases comprised another lung cancer high risk group (relative risk = 7.2, 95% confidence interval 0.5-103). A positive family history did not increase lung cancer risk among nonsmokers 60-84 years of age or their relatives. These findings suggest that susceptibility to lung cancer in families of nonsmoking cases may be evident only in a subset of relatives of early-onset nonsmoking cases.

Adenocarcinoma↗
PubMed1996

Antitumor activity of the Cu(II)-mitoxantrone complex and its interaction with deoxyribonucleic acid.

The effect of the Cu(II)-mitoxantrone complex on the DNA synthesis of HL-60 human leukemia cells has been studied by the technique of isotopic liquid scintillation. The results indicated that the complex shows a stronger ability to inhibit DNA synthesis of the tumor cells, and thus it may become a better antitumor drug. The interaction of mitoxantrone and its Cu(II) complex was studied by the methods of electrochemistry and spectroscopy. The complex gives rise to more changes on the conformation and the double-helical structure of DNA; this is closely related to the antitumor mechanism of the complex.

Animals↗
PubMed1996

Greatly accelerated lymphadenopathy and autoimmune disease in lpr mice lacking tumor necrosis factor receptor I.

Fas and TNF receptor I (TNF-RI) share homology at their cytoplasmic death domain and belong to the same gene family, but utilize different pathways to signal activation-induced cell death. To determine the combined effects of defective TNF-RI and Fas signaling on lymphadenopathy and autoimmune disease, we backcrossed TNF-RI knockout mice (Tnfr1(0/0)) with Fas-deficient C57BL/6-lpr/lpr mice. Tnfr1(0/0)lpr/lpr mice developed greatly accelerated lymphadenopathy and autoantibody production compared with C57BL/6-lpr/ lpr mice. Tnfr1(0/0)-lpr/lpr mice also exhibited high mortality and early onset autoimmune disease characterized by massive mononuclear cell infiltration in liver, kidney, lung, and knee joints. These results indicate that the Fas-mediated apoptosis defect in lpr mice is accelerated in the absence of TNF-RI and that normal expression of TNF-RI might partially compensate for the Fas-mediated apoptosis defect of mononuclear cells in lpr mice.

Animals↗
PubMed1996

Inhibition of Nur77/Nurr1 leads to inefficient clonal deletion of self-reactive T cells.

The Nur77/Nurr1 family of DNA binding proteins has been reported to be required for the signal transduction of CD3/T cell receptor (TCR)-mediated apoptosis in T cell hybridomas. To determine the role of this family of DNA-binding proteins in thymic clonal deletion, transgenic (Tg) mice bearing a dominant negative mutation were produced. The transgene consisted of a truncated Nur77 (deltaNur77) gene encoding the DNA-binding domain of Nur77 ligated to a TCR-beta enhancer resulting in early expression in thymocytes. Apoptosis of CD4+CD8+ thymocytes mediated by CD3/TCR signaling was greatly inhibited in the deltaNur77 Tg mice, compared with non-Tg littermates, after treatment with anti-CD3 or anti-TCR antibody in vivo and in vitro. Clonal deletion of self-reactive T cells was investigated in deltaNur77-Db/HY TCR-alpha/beta double Tg mice. There was a five-fold increase in the total number of thymocytes expressing self-reactive Db/HY TCR-alpha/beta in the deltaNur77-TCR-alpha/beta double Tg male mice. Deficient clonal deletion of self-reactive thymocytes was demonstrated by a 10-fold increase in the CD4+CD8+ thymocytes that expressed Tg TCR-alpha/beta. There was an eightfold increase in the CD8+, Db/HY TCR-alpha/beta T cells in the lymph nodes (LN) of delta Nur77-Db/HY TCR-alpha/beta double Tg compared with Db/HY TCR-alpha/beta Tg male mice. In spite of defective clonal deletion, the T cells expressing the Tg TCR were functionally anergic. In vivo analysis revealed increased activation and apoptosis of T cells associated with increased expression of Fas and Fas ligand in LN of deltaNur77-Db/HY TCR-alpha/beta double male mice. These results indicate that inhibition of Nur77/Nurr1 DNA binding in T cells leads to inefficient thymic clonal deletion, but T cell tolerance is maintained by Fas-dependent clonal deletion in LN and spleen.

Animals↗
PubMed1996

Analysis of the growth and transformation suppressor domains of promyelocytic leukemia gene, PML.

The promyelocytic leukemia gene (PML) involved in the t(15;17) (q22;q12) translocation in acute promyelocytic leukemia is a growth suppressor. To elucidate the functional domains of PML, several mutants lacking the nuclear localization signal (PMLnls-), the dimerization domain (PMLdim-), the proline-rich domain at the N-terminal (PMLpro-), the proline-rich RING finger motif (PMLpr-), the proline-rich RING finger B-box-1 (PML-prb-), the serine-proline-rich domain at the C-terminal (PMLsp-), and the double mutant (PMLprb-nls-) have been constructed. Immunofluorescence staining of transiently transfected NIH3T3 cells demonstrated that the RING finger motif, dimerization domain, and nuclear localization signal are all required for the formation of PML oncogenic domains (PODs). Immunofluorescence staining of transiently transfected GM637D human fibroblasts indicated that expression of PMLprb-, PM-Lnls-, and PMLprb-nls- led to a significant reduction or, in some cases, complete elimination of PODs. PMLdim-, PMLnls-, PMLpr-, PMLprb-, and PMLprb-nls- mutants were found to lose their ability to suppress transformation of NIH3T3 cells by activated neu, while PMLpro- and PMLsp- mutants did not. These results suggest that the ability of PML to form a POD is essential for suppression of growth and transformation. Furthermore, since PMLprb-, PMLnls-, and PMLprb-nls- mutants could block the suppression effect of wild-type PML on transformation of NIH3T3 cells by the neu oncogene, these PML mutants are potential dominant negative inhibitors of PML. Our study also suggests that the RING finger motif may interact with other nuclear proteins.

3T3 Cells↗
PubMed1996

C-Ha-ras oncogene in oral leukoplakia tissues.

The amplification and the G-T mutation at codon 12 of the C-Ha-ras oncogene in oral leukoplakia tissues were analyzed by using polymerase chain reaction (PCR) and molecular biologic technique. The results showed that these tissues had no amplification of Ha-ras oncogene. Only one case harbored G-T mutation in 11 oral leukoplakias, but this mutation was absent in 10 normal oral mucosal tissues. The possible role and significance of C-Ha-ras oncogene in oral precancerous lesions were also discussed.

Base Sequence↗
PubMed1996

Preconcentration of trace elements from natural water with palladium precipitation.

Palladium salts can be used as a coprecipitation carrier for the preconcentration of trace elements from natural water prior to their measurement by atomic spectrometry (AAS). The palladium is subsequently reduced by the introduction of hydrogen gas into the sample solution. The procedure is applied to the determination of Cu, Pb and Cd in seawater (enrichment factor 50) and synthetic water samples. Operating conditions have been optimized for the analysis of real samples. With the technique established an enrichment factor (500 fold) is feasible in synthetic samples. The recoveries of Cu, Cd and Pb from seawater are 95, 103 and 100%, respectively. This simple and rapid method can be applied in a wide pH-range and with complex matrices.

Journal Article↗
PubMed1996

Management of acute myocardial infarction: evaluating the past, practicing in the present, elaborating the future.

The management of acute myocardial infarction initially focused on treatment and/or prevention of complications. In the prethrombolytic era, therapeutic regimens mainly comprised the use of antianginal and antiarrhythmic drugs. The development of semi-invasive hemodynamically guided treatment concepts led to remarkable improvement in clinical outcome. After the introduction of the "wave-front phenomenon," multiple pharmacologic treatment strategies were developed with the goal of infarct size reduction. The use of thrombolytic agents reduced infarct size and improved prognosis of patients with acute myocardial infarction. Acute angioplastic intervention was introduced in specialized centers to achieve rapid restoration of coronary blood flow. The protection of the myocardium from reperfusion injury, however, remains an unresolved issue. Intravenous magnesium administration in conjunction with new and better recanalization techniques could therefore be a promising therapy strategy in patients with acute myocardial infarction.

Angioplasty, Balloon, Coronary↗