[Experimental study of amplifying SEN virus with different probes and primers].
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China↗
Biomedical subjects
Li Jing
Publications and source records attributed to Li Jing.
Predicting protein structure from long-range contacts.
Short-range and long-range contacts are important in forming protein structure. The proteins can be grouped into four different structural classes according to the content and topology of alpha-helices and beta-strands, and there are all-alpha, all-beta, alpha/beta and alpha+beta proteins. However, there is much difference in statistical property for those classes of proteins. In this paper, we will discuss protein structure in the view of the relative number of long-range (short-range) contacts for each residue. We find the percentage of residues having a large number of long-range contacts in protein is small in all-alpha class of proteins, and large in all-beta class of proteins. However, the percentage of residues is almost the same in alpha/beta and alpha+beta classes of proteins. We calculate the percentage of residues having the number of long-range contacts greater than or equal to (>/=) N(L)=5, and 7 for 428 proteins. The average percentage is 13.3%, 54.8%, 41.4% and 37.0% for all-alpha, all-beta, alpha/beta and alpha+beta classes of proteins with N(L)=5, respectively. With N(L) increasing, the percentage decreases, especially for all-alpha class of proteins. In the meantime, the percentage of residues having the number of short-range contacts greater than or equal to N(S) (>/=N(S)) in protein samples is large for all-alpha class of proteins, and small for all-beta class of proteins, especially for large N(S). We also investigate the ability of amino residues in forming a large number of long-range and short-range contacts. Cys, Val, Ile, Tyr, Trp and Phe can form a large number of long-range contacts easily, and Glu, Lys, Asp, Gln, Arg and Asn can form a large number of long-range contacts, but with difficulty. We also discuss the relative ability in forming short-range contacts for 20 amino residues. Comparison with Fauchere-Pliska hydrophobicity scale and the percentage of residues having large number of long-range contacts is also made. This investigation can provide some insights into the protein structure.
Amino Acids↗
The potential molecular targets of marine sulfated polymannuroguluronate interfering with HIV-1 entry. Interaction between SPMG and HIV-1 rgp120 and CD4 molecule.
The potential targets of marine sulfated polymannuroguluronate (SPMG) involved in inhibition of HIV-1 entry were investigated by surface plasmon resonance and flow cytometry. Results indicated that binding of SPMG either to soluble oligomeric rgp120 or to complexed rgp120-sCD4 mainly resided in V3 loop region. In addition, SPMG was shown to be less accessible for sCD4 when sCD4 had pre-interacted with rgp120, though SPMG per se multivalently bound to sCD4 with relatively low affinity. While the pre-incubation of SPMG with rgp120 caused a partial blockade of rgp120 binding to sCD4, suggesting that SPMG either shared common binding sites on gp120 with sCD4 or masked the docking sites of gp120 for sCD4. Taken together, V3 domain was demonstrated to be the major site mediating interaction of SPMG with complexed rgp120-sCD4. It seems likely that SPMG binds to both rgp120 and sCD4, but has less accessibility for sCD4 when sCD4 has already bound to rgp120. Nevertheless, addition of SPMG either prior to or after the interaction of rgp120 with sCD4 may suppress rgp120 binding to sCD4. The exact pattern of this trimolecular complex formation at the cell membrane-anchored virus level requires further clarification.
Anti-HIV Agents↗
[Expression and clinical significance of surfactant protein D mRNA in peripheral blood of lung cancer patients].
BACKGROUND AND OBJECTIVES: The sensitive detection of circulating tumor cells in lung cancer patients is very important for prognosis and selection of appropriate treatment modalities. Based on recent promising data, the authors established reverse transcriptase (RT)-PCR with primers specific for surfactant protein D (SP-D) gene to detect circulating tumor cells in the peripheral blood of lung cancer patients, and to initiatively discuss its clinical significance. METHODS: The expression of SP-D mRNA was analyzed by an improved nested RT-PCR in the peripheral blood of 26 lung cancer patients with metastases, 37 lung cancer patients without metastases, 15 benign pneumonia patients, and 15 healthy volunteers. RESULTS: 1) The sensitivity of the method was 1 x 10(-6), with high level of specificity. 2) Using this method, the positive detection rate of the expression of SP-D mRNA was 92.3% (24/26) and 24.3% (9/37) in the peripheral blood of lung cancer patients with and without metastases, respectively. While no sample was positive for SP-D mRNA expression in the benign pneumonia patients and in the healthy volunteers. CONCLUSIONS: SP-D mRNA might be a valuable marker to detect circulating tumor cells in the peripheral blood of lung cancer patients. This method may be a valuable tool for early identification of metastases in asymptomatic lung cancer patients. Furthermore, it can also provide important clinical information for the evaluation of prognosis and in the selection of appropriate treatment strategies.
Actins↗
Determination of multiclass pesticide residues in apple juice by gas chromatography-mass selective detection after extraction by matrix solid-phase dispersion.
A multiresidue method is described for the analysis of 106 multiclass pesticides (organochlorine, organophosphate, carbamate, pyrethroid, and triazine classes) in apple juice in a single injection. The determination procedure was based on matrix solid-phase dispersion of juice on diatomaceous earth in a glass column and subsequent extraction with a mixture of hexane-dichloromethane (1 + 1) at a flow rate of 5 mL/min. The analytes were determined by capillary gas chromatography with mass spectrometric detection and confirmed by their retention times and ion ratios. The coefficients of variation for analysis of samples fortified over the range of 0.01-0.2 mg/kg were 1.62 to 18.4%, and the recoveries for all analytes were between 70 and 110%.
Beverages↗