Biomedical subjects

Xing Zhang

Publications and source records attributed to Xing Zhang.

77 records · Page 5Linked to original sources

PubMed2002

Synergy among nuclear receptor coactivators: selective requirement for protein methyltransferase and acetyltransferase activities.

Hormone-activated nuclear receptors (NR) bind to specific regulatory DNA elements associated with their target genes and recruit coactivator proteins to remodel chromatin structure, recruit RNA polymerase, and activate transcription. The p160 coactivators (e.g., SRC-1, GRIP1, and ACTR) bind directly to activated NR and can recruit a variety of secondary coactivators. We have established a transient-transfection assay system under which the activity of various NR is highly or completely dependent on synergistic cooperation among three classes of coactivators: a p160 coactivator, the protein methyltransferase CARM1, and any of the three protein acetyltransferases, p300, CBP, or p/CAF. The three-coactivator functional synergy was only observed when low levels of NR were expressed and was highly or completely dependent on the methyltransferase activity of CARM1 and the acetyltransferase activity of p/CAF, but not the acetyltransferase activity of p300. Other members of the protein arginine methyltransferase family, which methylate different protein substrates than CARM1, could not substitute for CARM1 to act synergistically with p300 or p/CAF. A ternary complex of GRIP1, CARM1, and p300 or CBP was demonstrated in cultured mammalian cells, supporting a physiological role for the observed synergy. The transfection assay described here is a valuable new tool for investigating the mechanism of coactivator function and demonstrates the importance of multiple coactivators, including CARM1 and its specific protein methyltransferase activity, in transcriptional activation.

Acetyltransferases↗

PubMed2002

Synthesis and insecticidal activity of novel 4beta-halogenated benzoylamino podophyllotoxins against Pieris rapae Linnaeus.

Twelve new 4beta-halogenated benzoylamino compounds (7.1-7.12) of podophyllotoxin have been synthesized, and their structures were confirmed by IR, 1H-NMR, MS spectra as well as CHN elemental analysis. These compounds showed delayed insecticidal activity against 5th instar larvae of Pieris rapae Linnaeus in vivo, when tested by a leaf-dipping method at a concentration of 250ppm. By preliminary qualitative structure-activity relationship analysis, we found the following results: 1) Compounds 7.2, 7.5-7.9 were more potent than the nature parent product in the mortality after 15 d against P. rapae in vivo. Especially compounds 7.5 and 7.6 bearing meta- and para-chlorobenzene substituents respectively, were the most potent of these compounds; 2) Substitution on the benzene ring moiety of 4beta-benzoylamino podophyllotoxin (PPT) with Cl, Br, I at the para or at the meta position yielded compounds which were as potent or more potent than those containing the corresponding substituting group at the ortho position. 3) Substitution on the benzene ring moiety of 4beta-benzoylamino podophyllotoxin with I either at the ortho, meta or para position yielded less potent compounds (7.10-7.12) when compared with PPT.

Animals↗

PubMed2002

[Significance of combined determination of CK19mRNA, carcinoembryanic antigen, neuron-specific enolase, and tissue polypeptide antigen in peripheral blood of patients with lung cancer].

BACKGROUND & OBJECTIVE: Cellular keratin, an indicator for cancer cell in circulation gains increasing attention. Although CK19mRNA as a gene marker used to identify micro-metastasis is of relatively high practical value, it lacks specificity and sensitivity in diagnosis of cancer. The aim of this study is to evaluate whether the combined detection of CK19mRNA with other tumor markers, such as carcinoembryanic antigen(CEA), neuron-specific Enolase(NSE), tissue polypeptide antigen(TPA), would improve the diagnosis of lung cancer. METHODS: The expression level of CK19mRNA in peripheral blood mononucleated cells (PBMCS) was determined by RT-PCR, The levels of CEA, NSE, and TPA in serum were determined by enzyme-linked immunosorbent assay (ELISA) and time-resolved fluorometry(TRF) in 91 patients with lung cancer, 33 with benign lung diseases (BLD) and 50 healthy controls. The data was analyzed by t test and chi 2 test. RESULTS: The positive rates of CK19mRNA, CEA, NSE, and TPA in lung cancer group (49.5%, 65.9%, 67.0%, and 83.5%, respectively) were remarkably higher than in BLD group(24.2%, 9.0%, 15.2%, and 9.0%, respectively) and in healthy control group (10.0%, 4.0%, 8.0%, and 6.0%, respectively) (P < 0.01). The positive rate of CK19mRNA was not statistically different in various histological subtypes (P > 0.05). Although the positive rate of CK19mRNA appeared to be associated with the clinical stage (stage I + II: 44.4%, stage III: 48.4%, stag IV: 54.2%), there was no statistical significance among the three groups (P > 0.05). The serum level (microgram/L)/positive rate of CEA(3.5/27.8%, 5.1/35.5%, and 8.5/58.3%, respectively), NSE (12.5/33.3%, 15.3/41.9%, and 24.7/58.3%, respectively), and TPA (1.1/44.4%, 1.8/58.1%, and 3.6/66.7%, respectively) in stage I + II, III, and IV appeared to be associated with the clinical stages of lung cancer, but no statistical significance among the three groups (P > 0.05). Combined detection of three or four tumor markers yielded significant higher effective accuracy in diagnosis of lung cancer than that of any of two tumor markers or single tumor marker (P < 0.05). In addition, the results showed that TPA, CEA, and NSE were relatively specific for squamous cell carcinoma (76.7%), adenocarcinomas (83.3%), and small-cell lung cancer (79.2%), respectively. CONCLUSION: The combined measurement of CK19mRNA with CEA, NSE, and TPA can increase diagnosis rate of lung cancer, can also provide potent diagnosis basis for treatment.

Adult↗

PubMed2002

[Effects of rush-mat dust on the health of exposed workers].

OBJECTIVE: To evaluate the effect of exposure to rush-mat dust on the health of workers. METHODS: A cross sectional study of 661 workers (349 men, 312 women) from 35 rush-mat plants was carried out by using occupational health investigation, questionnare and physical examination. RESULTS: The geometric mean total dust concentration in the workshop was up to 20.00 mg/m3, and the geometric mean respirable dust concentration reached 8.22 mg/m3. The mean free SiO2 concentration of accumulated dust was 25.6%. The prevalence of radiographic small opacities profusion category > or = 1/0, according to the China Classification for pneumoconiosis (GB 5906-2000), and compared with the ILO 1980 system, was 2.57%. Even more, one man had category 2 pneumoconiosis with progressive massive fibrosis. However, the incidence of pneumoconiosis (1/0 at least) was correlated with work duration and dust concentration(r = 1.156, P < 0.001; r = 0.106, P = 0.006, respectively). Some positive correlations were found between the incidence of cough or expectoration and occupational exposure (r = 0.085, P = 0.028; r = 0.094, P = 0.016, respectively). CONCLUSION: To our knowledge, this is the first report of rush pneumoconiosis in China. The results have offered the possibility of a dose-response relationship between rush-mat dust and pneumoconiosis. More investigation in this area is need.

Aluminum Silicates↗

PubMed1999

Structure of Cytoplasmic Polyhedrosis Virus from Bombyx mori.

The structures of full and empty capsids of CPV were studied by negative staining and electron cryomicroscopy and computer reconstruction techniques. By comparing the structures and biochemical compositions, the CPV was identified as a single-layered capsid with its five structural proteins located on it. This single capsid is arranged according to T=1 icosahedral symmetry with 12 turret-like spikes at its icosahedral vertices. The empty and full CPV show identical capsid but differ inside. The dense and ordered genomic dsRNA is located inside the full CPV. The internal space of the empty CPV has almost no electron density except for 12 electron densities attributed the transcriptional enzyme complexes extending inward from the base part of CPV spikes.

Journal Article↗