Biomedical subjects

P Yang

Publications and source records attributed to P Yang.

At least 217 records · Page 12Linked to original sources

PubMed1998

[Isolation and structure of 6'-O-caffeylerigeroside from Erigeron multiradiatus].

The plant, Erigeron multiradiatus (Wall.) Benth(Family: Compositae), is a perennial herb distributed abundantly in the mountainous area of the southwestern part in China. It is used in folk medicine for the treatment of common cold, panting cough, rheumatic, enteritis and toothache. In this paper, we report a new glycoside named as 6'-O-caffeylerigeroside isolated from Erigeron Multiradiatus (Family: Compositae) together with four known compounds. The known compounds were identified as pyromeconic acid(I), scopoletin(II), 4-hydroxybenzoic acid(III) and vanillic acid(IV). The structure of 6'-O-caffeylerigeroside was elucidated as gamma-pyrone-3-O-[6"-(3',4'-dihydroxy-cinnamoyl)]-beta-D-glucoside(V) on the basis of chemical evidence and spectral data.

Asteraceae↗

PubMed1998

[Gene cloning, expression and immunological identification of a single chain antibody fragment 3D3 against dengue type 3 virus].

Hybridoma 3D3 which secreted monoclonal antibody against Dengue type 3 virus was used to extract mRNA and then was reverse-transcripted into cDNA for amplifying heavy and light chain variable domain genes. The amplified light and heavy chain variable domain genes were connected by flexible linker to form a single chain antibody fragment (ScFv) gene of 750 bp, which was cloned into phage pCANTAB5 vector using the recombinant phage antibody system. The ScFv gene was expressed as fusion protein with phage g3p coat protein and displayed on the phage surface. The phagemid was used to transform competent E. coli TG1 cells and then infected with M13K07 helper phage to rescue the phagemid and antibody ScFv gene. 12 of the 20 randomized clones were shown to react with dengue type 3 virus by immunofluorescence.

Antibodies, Monoclonal↗

PubMed1998

[Soluble expression and identification of expressed single chain antibody fragment 3D3 against dengue virus type 3].

Hybridoma secreting 3D3 monoclonal antibody against dengue virus type 3 was used. The isolated mRNA was reverse-transcribed into cDNA for amplifying the heavy and light chain variable domains genes. The amplified light and heavy chain variable domains' genes were connected by flexible linker to from a single chain fragment (ScFv) gene of 750 bp, which was cloned into phage pCANTAB5E vector using the recombination phage antibody system. pCANTAB5E vector transformed E coli HB2151. Soluble single chain antibody fragment was expressed both in the bacterial supernatant and cell periplasm under the induction of IPTG. The expressed single chain antibody fragment has a molecular weight of about 28 kD detected by SDS-PAGE and can react with dengue virus type 3 by immunofluorescence test.

Antibodies, Monoclonal↗

PubMed1998

[Serum soluble interleukin-2 receptor levels in uveitis].

PURPOSE: To investigate the relationship between serum SIL-2R levels and uveitis. METHODS: SIL-2R levels were measured in sera of 64 patients with active uveitis by ELISA assay, 61 healthy subjects as control. RESULTS: Serum SIL-2R levels in the patients with active uveitis were significantly higher than that in the controls, but there were no significant difference among anterior uveitis, intermediate uveitis, Behcet disease and Vogt-Koyanagi-Harada syndrome. After therapy the serum SIL-2R levels were obviously decreased. CONCLUSION: SIL-2R Levels in serum correlate with activity of uveitis.

Adolescent↗

PubMed1998

[Measurements of Ar(I) excitation temperatures and electron number densities in an ICP with and without the presence of Freon 12--the development of ICP technology for hazardous waste management].

For the management of refractory hazardous wastes, an innovative technology emerging recently is the application of ultra high temperature plasma. The preliminary study on destruction of Freon 12 by ICP (1-2kW) under a joint program between Xiamen Univ. and Hong Kong Baptist Univ. showed that the ICP technology indeed holds a great potential for hazardous wastes management. The destruction efficiency is more than 99.9999%. With and without the presence of Freon 12, Ar(I) excitation temperatures were measured by Boltzmann plot method and electron number densities the by H (beta) line broadening method. It was found that above the load coil, the excitation temperatures and electron number densities decrease with increasing the amount of Freon 12 presented in the central channel of the ICP, but inside the load coil region, the excitation temperatures are affected little by Freon 12. The conclusion of thermal pinch could be expected from this phenomenon.

Argon↗

PubMed1998

[Influences of Freon-12 (CF2CCl2) on the electron number densities in an inductively coupled plasma (ICP) measured with Halpha line--the applications of ICP in the disposal of hazardous waste].

The inductively coupled plasma was applied to decompose Freon 12 (CF2CCl2). The efficiency of the decomposition was indirectly evaluated by comparing the electron number densities in the central channel of the ICP with the addition of different amounts of Freon-12. Halpha line (656.3nm) was used to measure the electron number density due to Hbeta line (486.1nm) is seriously interfered with the addition of Freon-12 under the selected operating conditions. The "thermal pinch" effect was found with the addition of Freon-12, which is beneficial to the complete decomposition of the compound.

English Abstract↗

PubMed1998

[Correction of spectral interferences by ICP-AES primary expert system].

A subpackage for spectral interference correction has been set up in ICP-AES primary expert system. Some numerical recipes have been applied in this subpackage, such as curve smoothing, derivative spectrum, FFT technique, spectral resolving etc. A comprehensive method for spectral interference correction is presented. All these numeric recipes have been tested with simulated data and also utilized in several typical examples of real spectra. Results are satisfactory.

English Abstract↗

PubMed1998

[Study of spectral interferences of REEs with the matrix of dy for a high resolution ICP-AES].

The spectral interferences of the matrix of Dy on other REEs have been studied for a high resolution ICP-AES with a grating of 3600 grooves/mm. 66 analytical lines of 14 REEs have been selected as the prominent lines in the spectral interference studies. Three kinds of databases for Dy lines have been established for the spectra search and recognition. Thus, these databases can provide information of Dy lines accurately and conveniently.

English Abstract↗

PubMed1998

[Study of the excitation and diffusion processes of sample atoms in a microwave boosted microsecond-pulse glow discharge source with optical emission spectrometry].

The excitation and diffusion processes of brass sample atoms in a GD-MIP tandem source have been studied with a home-made MIP boosted micros-pulse GD device. Experimental results show that under relatively low discharge pressure (< 180Pa), the micros-pulse GD can couple quite well with MIP and emit strong radiation of analytical lines. When the GD source is operated under a pressure higher than 200Pa, two emission peaks appear independently in time for a given resonant atomic line, because sample atoms are structurally excited separately first by the micros-pulse GD and then by the MIP. According to the two emission peaks, the diffusing velocities of copper atoms and zinc atoms can be calculated, yielding values of 150 and 129m/s, respectively, and the most excited area in-the micros-pulse GD is about 1.94-2.25mm away from the sputtering surface of the sample cathode. The effects of discharge parameters on emission intensities have been also investigated.

English Abstract↗

PubMed1998

Analysis of age of onset data from case-control family studies.

Age of onset data from case-control family studies are frequently used to study the relationship between disease and environmental or genetic factors. Dependence of age of onset within family and case-control sampling designs must be taken into account in analyzing such data. In this paper, we propose a parametric likelihood approach to study the relationship between disease risk and covariates, allowing for any correlations in age of onset of disease between family members and to study the familial association in age of onset of disease due to genetic factors, after adjusting for other shared covariates within the family. The method provides a way to combine the information relating disease incidence to risk factors in relatives with the information contained in the case/control contrasts in order to obtain more precise estimates of the effects of the putative risk factors. A data set from a case-control family study of lung cancer is used to illustrate the method. The analysis indicated that history of smoking, passive smoking, and history of chronic obstructive pulmonary disease are positively associated with lung cancer risk, and that, after adjustment for these risk factors, there is little evidence of familial aggregation in lung cancer risk.

Adult↗

PubMed1998

Parallel comparative trial of amlodipine and nitrendipine monotherapy in patients with essential hypertension.

OBJECTIVES: To compare the blood pressure effects of two dihydropyridine calcium channel blockers, amlodipine and nitrendipine, in 488 patients with essential hypertension. METHODS: The study used a randomized, single-blind design of 4 weeks' duration conducted at four medical centres in China. Patients were randomized to receive either amlodipine monotherapy (5-10 mg once daily; n = 334) or nitrendipine (10 mg twice or three times daily; n = 1 54). Blood pressure was evaluated by standard blood pressure measurements before and after treatment, and by 24 h ambulatory blood pressure monitoring in a subgroup of patients (n = 18). RESULTS: Both systolic and diastolic blood pressures were reduced from baseline after 4 weeks of amlodipine and nitrendipine monotherapy. Diastolic blood pressure was reduced by 14.4% in the amlodipine group, which was significantly better than the 13.0% reduction in the nitrendipine group (P< 0.05). In addition, blood pressure response rates were significantly better with amlodipine monotherapy than with nitrendipine monotherapy. In the subgroup of patients undergoing 24 h ambulatory blood pressure monitoring, both systolic and diastolic blood pressure were reduced from baseline in the amlodipine and nitrendipine groups. Adverse effects were generally mild, with dizziness, flushing, palpitation, headache, drowsiness and ankle oedema being the most common. Rushing and headache were more frequent in the nitrendipine group than in the amlodipine group (P< 0.05 for flushing and P<0.01 for headache). CONCLUSIONS: Amlodipine monotherapy reduced blood pressure more effectively than nitrendipine monotherapy in patients with essential hypertension and was associated with fewer adverse events.

Adult↗

PubMed1997

Synthesis and DNA binding studies of cobalt (III) mixed-polypyridyl complex.

The complex of Co(phen)2dppz3+ (where phen is ophenanthroline, and dppz is dipyrido [3, 2-a: 2', 3'-c] phenazine) has been synthesized. This complex was characterized by elemental analysis, molar conductivity, IR and 1H NMR spectroscopy. The interaction of the complex with calf thymus DNA has been studied using absorption and emission spectroscopy, DNA melting techniques, cyclic voltammetric, viscosity, and electrophoresis measurements. The compound shows absorption hypochromicity, fluorescence enhancement, DNA melting temperature, and the specific viscosity increased when binding to calf thymus DNA. CV measurement shows that the shifts in oxidation-reduction potential and change in peak current with addition of DNA. The complex is also shown to be more efficient photosensitisers for single strand breaks in plasmid DNA.

Cobalt↗

PubMed1997

Experimental antitumor activity of the Ce(IV)-mitoxantrone complex and its interaction with deoxyribonucleic acid.

The Ce(IV)-mitoxantrone complex exhibits a higher lethality to Ehrlich ascites tumor cells than that of the free drug and shows stronger inhibition ability on the DNA synthesis of the tumor cells. Thus the Ce(IV)-mitoxantrone complex may become a more potent antitumor drug than mitoxantrone. The different interaction model of mitoxantrone and its Ce(IV) complex with DNA were studied by the methods of spectroscopy, electrochemistry, and electrophoresis. Ce(IV) ions chelate with oxygens of the hydroxyl groups at the 1,4 position and the carbonyl function on C-9 and C-10, then intercalate into the base pairs of DNA together. The complexation of Ce(IV) gives rise to more compact binding of mitoxantrone with DNA, and leads to an additional change on the normal conformation and the double-helical structure of DNA; this may be related to the more stronger action of the complex on DNA synthesis and survival of cultured tumor cells.

Animals↗

PubMed1997

Increased lymphocyte apoptosis in Fas ligand transgenic mice.

Fas ligand (fasL) transgenic (Tg) mice were produced by introducing a murine fasL cDNA under the control of a TCR beta-chain enhancer minigene. Higher levels of fasL expression with increased biologic activity were observed in the Tg mice compared with non-Tg mice. Numbers of CD4+ CD8+ T cells in the thymus and T cells in the lymph node and spleen were lower in the fasL Tg mice compared with the non-Tg mice. This is consistent with a reduction in the size of the T cell areas in fasL Tg mice compared with non-Tg mice. Conversely, in fasL Tg mice, there was an increase in the number and size of apoptotic foci associated with phagocytic cells, as determined by in vivo TUNEL (TdT-mediated dUTP nick-end labeling) staining. Stimulation of non-Tg mice in vivo with anti-CD3 Ab for 3 days resulted in greatly increased apoptosis of CD4+ CD8+ thymocytes and lymph node T cells. Surviving thymocytes and T cells of lymph node and spleen expressed Fas at low levels. After similar stimulation of fasL Tg mice, however, a discreet population of surviving cells expressed high levels of Fas, indicating that a novel population of Fas apoptosis-resistant cells develops in these mice. These results indicate that high levels of fasL can result in both increased Fas-mediated apoptosis and the development of T cells that express high levels of Fas, but are resistant to Fas-mediated apoptosis.

Animals↗

PubMed1997

Genetic dissection of systemic lupus erythematosus pathogenesis: Sle2 on murine chromosome 4 leads to B cell hyperactivity.

Susceptibility to systemic lupus erythematosus in the NZM2410 murine model maps to Sle1, Sle2, Sle3, and the H2 loci. To unravel how these loci contribute to the pathogenesis of lupus, individual NZM2410-derived genomic intervals bearing these loci have been successfully backcrossed onto the resistant C57BL/6 (B6) background. The focus of this study was to understand how Sle2 on murine chromosome 4 impacts the immune system. Compared with C57BL/6 (B6) mice, B6 mice congenic for Sle2 exhibit a variety of immunophenotypes affecting their B cells. They have an early, but transient, expansion of splenic, CD23(low) B cells. Thereafter, their B cells appear activated by surface phenotype and functional criteria, paralleled by elevated serum levels of polyreactive/polyclonal IgM. Importantly, Sle2 leads to a heightened B cell responsiveness to in vitro stimuli and to in vivo antigenic challenge. Finally, they exhibit increased levels of peritoneal and splenic B1 cells. Thus, Sle2 harbors a gene that leads to B cell hyperactivity and elevated B1 cell formation. However, Sle2 by itself on the normal B6 background is insufficient to generate IgG antinuclear Abs (ANA) or nephritis. By reducing the B cell signaling threshold, Sle2 might serve to amplify an ongoing autoimmune response.

Animals↗

PubMed1997

Pro-oxidant effects of delta-aminolevulinic acid (delta-ALA) on Chinese hamster ovary (CHO) cells.

delta-Aminolevulinic Acid (delta-ALA) is a heme precursor accumulated in lead poisoning and acute intermittent porphyria. Although no single mechanism for lead toxicity has yet been defined, recent studies suggest at least some of the lead-induced damage may originate from delta-ALA-induced oxidative stress. The present study was designed to test the hypothesis that delta-ALA accumulation in Chinese hamster ovary (CHO) cells contributes to the cumulative oxidative challenge of lead poisoning as indicated by the oxidative stress parameters glutathione (GSH), glutathione disulfide (GSSG), malondialdehyde equivalents (MDA), and catalase (CAT). It will also examine the possibility that this oxidative challenge can be reversed by treatment with an antioxidant such as N-acetylcysteine (NAC). First in vitro administration of delta-ALA to CHO cells was found to have a concentration-dependent inhibitory effect on colony formation and cell survival. NAC administration was shown to alleviate this inhibition in CHO survival. The oxidative status of CHO cell cultures exposed to increasing concentrations of delta-ALA was then examined. Decreases in GSH levels (P < 0.05) were observed in the delta-ALA-treated cultures as compared to the controls, while GSSG and MDA levels were significantly increased in delta-ALA-treated cells (P < 0.05). CAT activity was not significantly affected. NAC administration concurrent with delta-ALA exposure resulted in GSH and GSSG levels similar to the control levels, while no significant improvement in MDA was observed. These results indicate a state of oxidative stress and suggest that the delta-ALA- induced inhibitory effect on CHO colony formation may be due to its pro-oxidant effect. To assess whether this oxidative challenge would induce antioxidant increases during extended exposure to delta-ALA, CHO cells were exposed to 5 mM delta-ALA for increasing time periods. The GSH and GSSG levels were measured and a rebound effect was observed after 12 h of delta-ALA exposure.

Aminolevulinic Acid↗

PubMed1997

Hemagglutinin specificity and neuraminidase coding capacity of neuraminidase-deficient influenza viruses.

Neuraminidase (NA)-deficient mutant virus stocks have been obtained by passaging A/NWS/33HA-tern/Australia/G70c/75NA (H1N9) influenza virus in medium containing neuraminidase from Micromonospora viridifaciens and antiserum against the influenza NA. Growth of the resulting mutants is dependent on addition of bacterial neuraminidase to the medium. Nucleotide sequence analysis showed large single deletions in the NA genes, with both ends of the NA gene segments conserved. These RNA fragments all have the capacity to code for a peptide that contains the N-terminal "tail" and membrane-anchoring region of the NA, but the presence of this peptide has not been demonstrated in virions or infected cells. In contrast to the ease of selection of NA-deficient mutants from the H1N9 virus, no mutants were selected from three other viruses. The HA-coding segments of parental H1N9 and mutant NWSc-Mvi predict a change of Pro to His at residue 227 (H3 numbering), close to the receptor-binding site of H3 HA, compared to the HA of an H1N2 reassortant that contains the NWS/33 HA gene. This change may contribute to an altered HA specificity that allows selection of mutants that can infect cells in the presence of high levels of NA activity. It appears that the role of NA in influenza infection is to remove sialic acid from the HA rather than to destroy receptors on cells.

Amino Acid Sequence↗

PubMed1997

Genetic analysis of families with nonsmoking lung cancer probands.

As part of a genetic epidemiologic study of lung cancer among nonsmokers, we investigated the role of genetic predisposition in familial aggregation. Cases were identified from the Metropolitan Detroit Cancer Surveillance System. Information on lung cancer occurrence, smoking habits (active or passive), and chronic respiratory diseases in first-degree relatives was obtained for 257 nonsmoking lung cancer probands (71 males, 186 females) diagnosed at ages 40-84 years. Among the 2,021 first-degree relatives, 24 (2.6%) males and 10 (1.1%) females were reported as having lung cancer. The occurrence of lung cancer among smoking and nonsmoking relatives was 4.5% and 1.1% in males and 2.8% and 0.4% in females, respectively. To evaluate the role of a putative Mendelian gene (one locus, two alleles) in the presence of other risk factors, we performed complex segregation analyses on the data using two different regressive model approaches [Segregation Analysis of a Discrete Trait Under a Class A Regressive Logistic Model, V4.0 (REGD) and Segregation Analysis of a Truncated Trait, V2.0, Model 1(REGTL)] as implemented in the Statistical Analysis for Genetic Epidemiology (SAGE) program. Using either approach, an environmental model best explained the observed lung cancer aggregation in families ascertained through nonsmoking probands. Based on our final model, only 0.04% of this population had a very high risk and 4.2% had a moderate risk of lung cancer. The rest of the population had virtually no risk of lung cancer during their lifetime unless they have multiple risk factors. Among the high-risk individuals without any risk factor under study, the estimated risks at ages 40, 60, and 80 years in males were 16.7%, 83.6%, and 95.4%, and in females were 14.0%, 72.2%, and 88.0%, respectively. Among at-moderate-risk smokers the estimated risks at the same age and gender groups were essentially the same as in the high-risk nonsmokers. Our results suggest that the pattern of lung cancer occurrence in families of nonsmoking lung cancer patients differs from that in families of smoking lung cancer patients. Despite the profound effect of smoking on the risk of lung cancer, other environmental and/or genetic risk factors need to be identified.

Adult↗