PubMed Health⌕ Search

Biomedical subjects

Hui Li

Publications and source records attributed to Hui Li.

At least 55 records · Page 3Linked to original sources
PubMed2006

Identification of gamma-aminobutyric acid receptor-interacting factor 1 (TRAK2) as a trafficking factor for the K+ channel Kir2.1.

To identify proteins that regulate potassium channel activity and expression, we performed functional screening of mammalian cDNA libraries in yeast that express the mammalian K(+) channel Kir2.1. Growth of Kir2.1-expressing yeast in media with low K(+) concentration is a function of K(+) uptake via Kir2.1 channels. Therefore, the host strain was transformed with a human cDNA library, and cDNA clones that rescued growth at low K(+) concentration were selected. One of these clones was identical to the protein of unknown function isolated previously as gamma-aminobutyric acid receptor-interacting factor 1 (GRIF-1) (Beck, M., Brickley, K., Wilkinson, H., Sharma, S., Smith, M., Chazot, P., Pollard, S., and Stephenson, F. (2002) J. Biol. Chem. 277, 30079-30090). GRIF-1 specifically enhanced Kir2.1-dependent growth in yeast and Kir2.1-mediated (86)Rb(+) efflux in HEK293 cells. Quantitative microscopy and flow cytometry analysis of immunolabeled surface Kir2.1 channel showed that GRIF-1 significantly increased the number of Kir2.1 channels in the plasma membrane of COS and HEK293 cells. Physical interaction of Kir2.1 channel and GRIF-1 was demonstrated by co-immunoprecipitation from HEK293 lysates and yeast two-hybrid assay. In vivo association of Kir2.1 and GRIF-1 was demonstrated by co-immunoprecipitation from brain lysate. Yeast two-hybrid assays showed that an N-terminal region of GRIF-1 interacts with a C-terminal region of Kir2.1. These results indicate that GRIF-1 binds to Kir2.1 and facilitates trafficking of this channel to the cell surface.

Animals↗
PubMed2006

Method for the determination of blood methotrexate by high performance liquid chromatography with online post-column electrochemical oxidation and fluorescence detection.

Methotrexate (MTX) has been widely used at low dose for the treatment of different diseases including rheumatoid arthritis. MTX might be present in plasma in free form, and in blood cells in methotrexate polyglutamate (MTXPG). A rapid and sensitive HPLC method was developed for the determination of plasma MTX level, whole-blood MTX level, and whole-blood total MTX (MTX+MTXPG) level. To determine plasma MTX level or whole-blood MTX level, a 0.2-ml aliquot of plasma or whole blood (after a freeze-thaw cycle to break blood cells) was well mixed with 0.8 ml methanol and centrifuged. To determine whole-blood total MTX level, a 0.1-ml aliquot of whole blood (after a freeze-thaw cycle) was mixed with 80 microl ascorbic acid (114 mM) and incubated at 37 degrees C for 2h to enzymatically convert the MTXPG to MTX. Then 20 microl NaOH solution (0.5M) and 0.8 ml methanol were added and mixed well. After centrifugation, a 0.5-ml aliquot of the supernatant was evaporated to dryness and re-dissolved in 0.2 ml hydrochloric acid (10mM). Methylene chloride (0.2 ml) was added and mixed well. After centrifugation, the top aqueous layer was injected to HPLC for analysis. After the MTX was eluted from the HPLC column, it was electrochemically oxidized and detected by a fluorescence detector. Recoveries of spiked MTX at ppb (ng/ml) level were between 87.9 and 118% with within-day relative standard deviation less than 5.2% and day-to-day relative standard deviation less than 9.8%. The limit of detection (LOD) and limit of quantitation (LOQ) of the described method were 1.2 and 2.6 ng/ml, respectively.

Arthritis, Rheumatoid↗
PubMed2006

Molecular contacts for chlorosome envelope proteins revealed by cross-linking studies with chlorosomes from Chlorobium tepidum.

Chlorosomes are unique light-harvesting antennae found in two phyla of green bacteria: Chlorobi and Chloroflexi. In the green sulfur bacterium Chlorobium tepidum, 10 proteins (CsmA, CsmB, CsmC, CsmD, CsmE, CsmF, CsmH, CsmI, CsmJ, and CsmX) exist in the chlorosome envelope. Chlorosomes from the wild type and mutants lacking a single chlorosome protein were cross-linked with the zero-length cross-linker 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) and analyzed by gel electrophoresis. Similar cross-linking products were observed when the time and temperature were varied or when EDC was replaced with glutaraldehyde. Specific interactions between chlorosome proteins in cross-linked products were identified by immunoblotting with polyclonal antibodies raised against recombinant chlorosome proteins. We confirmed these interactions by demonstrating that these products were missing in appropriate mutants. Confirming the location of CsmA in the paracrystalline baseplate, cross-linking showed that CsmA forms dimers, trimers, and homomultimers as large as dodecamers and that CsmA directly interacts with the Fenna-Matthews-Olson protein. Cross-linking further suggests that the precursor form of CsmA is inserted near the edges of the baseplate, where CsmA and pre-CsmA interact with CsmB and CsmF. Several chlorosome proteins, including CsmA, CsmC, CsmD, CsmH, CsmI, CsmJ, and CsmX, were shown to exist as homomultimers in the chlorosome envelope. On the basis of the structural information obtained from these cross-linking experiments, a model for the locations and interactions of the proteins of the chlorosome envelope is proposed.

Bacterial Proteins↗
PubMed2006

An accurate ab initio potential energy surface and calculated spectroscopic constants for BeH2, BeD2, and BeHD.

A three-dimensional potential energy surface for the ground electronic state of BeH(2) has been determined by three-dimensional spline interpolation over 6864 symmetry-unique ab initio points calculated at the icMRCI/aug-cc-pV5Z level and corrected for core-electron correlation computed at the MR-ACPF/cc-pCV5Z level. Calculated spectroscopic constants of BeH(2) and BeD(2) are in excellent agreement with recent experimental results: for 11 bands of BeH(2) and 5 bands of BeD(2) the root mean square (rms) band origin discrepancies were only 0.15(+/-0.09) and 0.46(+/-0.19) cm(-1), respectively, and the rms relative discrepancies in the inertial rotational constants (B([v])) were only 0.028% and 0.023%, respectively. Spectral constants for BeHD were predicted using the same potential surface. The effect of different interpolation methods on predicted potential function values and on the calculated level energies and spectroscopic constants has been examined.

Journal Article↗
PubMed2006

[Association of Taq I T/C and Fok I C/T polymorphisms of vitamin D receptor gene with outcome of hepatitis B virus infection].

OBJECTIVE: To determine whether Taq I T/C and Fok I C/T polymorphisms of vitamin D Receptor (VDR) gene was associated with the outcomes of hepatitis B virus (HBV) infection. METHODS: A total of 212 HBV self-limited infection individuals, 244 asymptomatic HBsAg carriers and 391 chronic hepatitis B (HB) patients were recruited to conduct a case-control study. VDR-Taq I T/C and VDR-Fok I C/T polymorphisms were examined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: The frequency of VDR-Fok I allele C in the chronic HB patients was 45.8%, significantly higher than 38.2% of the self-limited infection individuals (chi(2) = 6.43, P = 0.01). The frequencies of VDR-Fok I genotypes TT, TC, and CC in HB patients were 30.7%, 47.1%, and 22.2% respectively, and 41.0% (TT), 41.5% (TC), and 17.5% (CC) in the self-limited infection individuals. There was a statistically significant difference between HB patients and self-limited infection individuals (chi(2) = 6.76, P = 0.03). The results of univariate analysis showed that the subjects carrying VDR-Fok I CC/TC genotype had 1.57-fold elevated risk for developing chronic HB when they were infected HBV (OR = 1.57, P = 0.01). A multiple logistic regression analysis revealed that VDR-Fok I CC/CT was independently associated with chronic HB after adjusting both potential confounding effects of gender (OR = 1.70, P = 0.021). The statistically significant association between TaqI T/C polymorphism and outcome of HBV infection was not demonstrated in the study. The frequency of haplotype TC of VDR-TaqI and Fok I in HB patients was 2.3080%, significantly higher than 0.5391% of the self-limited infection individuals (chi(2) = 6.08, P = 0.01). However, the frequency of haplotype TT in the HB patients was 1.5283%, significantly lower than 3.7061% of the self-limited infection individuals (chi(2) = 5.65, P = 0.02) and 3.4820% of the HBV carriers (chi(2) = 5.12, P = 0.02). CONCLUSION: VDR gene polymorphism is probably an influence factor on the genetic susceptibility of HBV infection.

Adult↗
PubMed2006

Identification and structure-based optimization of novel dihydropyrones as potent HCV RNA polymerase inhibitors.

A novel class of non-nucleoside HCV NS5B polymerase inhibitors has been identified from screening. A co-crystal structure revealed an allosteric binding site in the protein that required a unique conformational change to accommodate inhibitor binding. Herein we report the structure-activity relationships (SARs) of this novel class of dihydropyrone-containing compounds that show potent inhibitory activities against the HCV RNA polymerase in biochemical assays.

Crystallography, X-Ray↗
PubMed2006

Role of HMGB1 in apoptosis-mediated sepsis lethality.

Severe sepsis, a lethal syndrome after infection or injury, is the third leading cause of mortality in the United States. The pathogenesis of severe sepsis is characterized by organ damage and accumulation of apoptotic lymphocytes in the spleen, thymus, and other organs. To examine the potential causal relationships of apoptosis to organ damage, we administered Z-VAD-FMK, a broad-spectrum caspase inhibitor, to mice with sepsis. We found that Z-VAD-FMK-treated septic mice had decreased levels of high mobility group box 1 (HMGB1), a critical cytokine mediator of organ damage in severe sepsis, and suppressed apoptosis in the spleen and thymus. In vitro, apoptotic cells activate macrophages to release HMGB1. Monoclonal antibodies against HMGB1 conferred protection against organ damage but did not prevent the accumulation of apoptotic cells in the spleen. Thus, our data indicate that HMGB1 production is downstream of apoptosis on the final common pathway to organ damage in severe sepsis.

Amino Acid Chloromethyl Ketones↗
PubMed2006

Photodynamic therapy agent with a built-in apoptosis sensor for evaluating its own therapeutic outcome in situ.

Identifying the extent of apoptosis in cells or tissues after cancer therapy in real time would be a powerful firsthand tool for assessing therapeutic outcome. We combined therapeutic and imaging functions in one agent, choosing photodynamic therapy (PDT) as an appropriate cancer treatment modality. This agent induces photodamage in irradiated cells and simultaneously identifies apoptotic cells by near-infrared fluorescence. This photodynamic therapy agent with a built-in apoptosis sensor (PDT-BIAS) contains a fluorescent photosensitizer used as an anticancer drug, connected to a fluorescence quencher by a caspase-3 cleavable peptide linker. We demonstrated that cleavage of the peptide linker by caspase-3, one of the executioner caspases involved in apoptosis, results in a detectable increase of fluorescence in solution and in cancer cells after PDT treatment. The apoptosis involvement and drug effectiveness were confirmed by Apoptag and cell viability (MTT) assays supporting the ability of PDT-BIAS to induce and image apoptosis in situ.

Apoptosis↗
PubMed2006

Nef-mediated suppression of T cell activation was lost in a lentiviral lineage that gave rise to HIV-1.

High-level immune activation and T cell apoptosis represent a hallmark of HIV-1 infection that is absent from nonpathogenic SIV infections in natural primate hosts. The mechanisms causing these varying levels of immune activation are not understood. Here, we report that nef alleles from the great majority of primate lentiviruses, including HIV-2, downmodulate TCR-CD3 from infected T cells, thereby blocking their responsiveness to activation. In contrast, nef alleles from HIV-1 and a subset of closely related SIVs fail to downregulate TCR-CD3 and to inhibit cell death. Thus, Nef-mediated suppression of T cell activation is a fundamental property of primate lentiviruses that likely evolved to maintain viral persistence in the context of an intact host immune system. This function was lost during viral evolution in a lineage that gave rise to HIV-1 and may have predisposed the simian precursor of HIV-1 for greater pathogenicity in humans.

Animals↗
PubMed2006

Charge transfer interaction in the effective fragment potential method.

An approximate formula is derived and implemented in the general effective fragment potential (EFP2) method to model the intermolecular charge transfer interaction. This formula is based on second order intermolecular perturbation theory and utilizes canonical molecular orbitals and Fock matrices obtained with preparative self-consistent field calculations. It predicts charge transfer energies that are in reasonable agreement with the reduced variational space energy decomposition analysis. The formulas for the charge transfer gradients with respect to EFP translational and rotational displacements are also derived and implemented.

Chemistry, Physical↗
PubMed2006

8-Hydroxyquinoline derivatives induce the proliferation of rat mesenchymal stem cells (rMSCs).

A series of 8-hydroxyquinoline derivatives with different substituted groups at 2- or 5-position have been synthesized and characterized. Their effects on the proliferation of the rat marrow-derived mesenchymal stem cells (rMSCs) have been evaluated by MTT assay and flow cytometry. We also analyzed the ability of these compounds to regulate the proliferation of rMSCs and the relationship with the structures of 8-hydroxyquinoline. Compounds 8-11, in which, the vinyl-substituents are on the 2-position of 8-hydroxyquinoline, appear to be able to induce the proliferation of rMSCs. These results show that compounds 8-11 provide a kind of new substances for regulating the proliferation of rMSCs.

Animals↗
PubMed2006

Identification of mouse orthologue of endogenous secretory receptor for advanced glycation end-products: structure, function and expression.

The cell-surface RAGE [receptor for AGE (advanced glycation end-products)] is associated with the development of diabetic vascular complications, neurodegenerative disorders and inflammation. Recently, we isolated a human RAGE splice variant, which can work as a decoy receptor for RAGE ligands, and named it esRAGE (endogenous secretory RAGE). In the present study, we have isolated the murine equivalent of esRAGE from brain polysomal poly(A)+ (polyadenylated) RNA by RT (reverse transcription)-PCR cloning. The mRNA was generated by alternative splicing, and it encoded a 334-amino-acid protein with a signal sequence, but lacking the transmembrane domain. A transfection experiment revealed that the mRNA was actually translated as deduced to yield the secretory protein working as a decoy in AGE-induced NF-kappaB (nuclear factor kappaB) activation. RT-PCR and immunoblotting detected esRAGE mRNA and protein in the brain, lung, kidney and small intestine of wild-type mice, but not of RAGE-null mice. The esRAGE expression was increased in the kidney of diabetic wild-type mice. The present study has thus provided an animal orthologue of esRAGE for clarification of its roles in health and disease.

Alternative Splicing↗
PubMed2006

Acute centralization of blood flow in compromised human fetuses evoked by uterine contractions.

BACKGROUND: During fetal hypoxia blood is redistributed to the brain ('brain-sparing'). Sequential changes of the cerebral and placental circulation in parallel in comparisons between basal conditions and acute hypoxic stress have not yet been thoroughly studied in human fetuses. AIM: To explore acute fetal middle cerebral artery (MCA) circulatory changes relative to umbilical artery (UA) blood flow in a clinical experimental model with hypoxic stress provoked by uterine contractions during an oxytocin challenge test (OCT). STUDY DESIGN: Prospective comparative between imminently compromised (OCT positive) and un-compromised (OCT negative) fetuses. SUBJECTS AND METHODS: 82 term pregnancies suspected of intrauterine growth restriction were exposed to simultaneous electronic fetal heart rate monitoring and Doppler recordings of pulsatility index (PI) in the UA and MCA during basal conditions and during uterine contractions and relaxations at an OCT. OUTCOME MEASURES: Sequential changes of UA and MCA PI, OCT positive vs. negative cases. Nonparametric statistics with a P < 0.05 considered significant. RESULTS: The UA PI was significantly higher in OCT positive cases (N = 10) compared with OCT negative cases (N = 72) during uterine contractions and relaxations, but not during basal measurements. During contractions and relaxations the MCA PI decreased significantly in both groups (brain-sparing), but significantly more in OCT positive cases. CONCLUSIONS: During acute hypoxic stress, changes towards a centralization of blood flow to the brain develop in imminently compromised (OCT positive) fetuses at an expense of the umbilicoplacental blood flow, and the brain-sparing flow is more pronounced than in un-compromised (OCT negative) fetuses.

Birth Weight↗
PubMed2006

Selection of anti-double-stranded DNA B cells in autoimmune MRL-lpr/lpr mice.

Abs to DNA and nucleoproteins are expressed in systemic autoimmune diseases, whereas B cells producing such Abs are edited, deleted, or inactivated in healthy individuals. Why autoimmune individuals fail to regulate is not well understood. In this study, we investigate the sources of anti-dsDNA B cells in autoimmune transgenic MRL-lpr/lpr mice. These mice are particularly susceptible to lupus because they carry a site-directed transgene, H76R that codes for an anti-DNA H chain. Over 90% of the B cells are eliminated in the bone marrow of these mice, and the few surviving B cells are associated with one of two Vkappa editors, Vkappa38c and Vkappa21D. Thus, it appears that negative selection by deletion and editing are intact in MRL-lpr/lpr mice. However, a population of splenic B cells in the H76R MRL-lpr/lpr mice produces IgG anti-nuclear Abs, and these mice have severe autoimmune organ damage. These IgG Abs are not associated with editors but instead use a unique Vkappa gene, Vkappa23. The H76R/Vkappa23 combination has a relatively high affinity for dsDNA and an anti-nuclear Ab pattern characteristic of lupus. Therefore, this Vkappa gene may confer a selective advantage to anti-DNA Abs in diseased mice.

Amino Acid Sequence↗
PubMed2006

[Adjuvant effect of CpG DNA recombinant plasmid on antigen of Cysticercus cellulosae].

In order to prove the adjuvant effect of CpG DNA recombinant plasmid, the total antibodies and their IgG2a subtype induced by antigen of Cysticercus cellulosae, and content of IL-4 and IFN-gamma secreted from splenic cell of mouse immunized were measured. The recombinant plasmids showed an adjuvant effect, and CpG2 was the best adjuvant among the plasmids. It is proved that the CpG DNA possesses a synergistic effect with AI(OH)3 and 206 adjuvant, and is an effective Th1 type adjuvant in mice.

Adjuvants, Immunologic↗
PubMed2006

C-H...O hydrogen bond in chloroform-triformylmethane complex: blue-shifted or red-shifted?

B3LYP/6-311+G** level of theory is used to investigate the C-H...O hydrogen bond formed by chloroform and two conformers of triformylmethane (TFM), i.e. cis-TFM (concerned with C1 configuration) and trans-TFM (concerned with C2 and C3 configurations). Polarized continuum model (PCM) is used to study the solvent (chloroform) effect on this hydrogen bond. The C3 configuration is more stable than the C1 configuration whether the absolute energy or the stabilization energy is concerned. For the C1 and C2 configurations this hydrogen bond is of blue-shifted type both in gas phase and in chloroform solution. For the C3 configuration this hydrogen bond is of red-shifted type in gas phase but turns into blue-shifted type in chloroform solution instead. It's inappropriate to simply designate this hydrogen bond as blue-shifted type or red-shifted type.

Chloroform↗
PubMed2006

Lignans from Saussurea conica and their NO production suppressing activity.

Three new lignan derivatives, conicaols A and B and conicaoside, together with seven known compounds were identified from Saussurea conica. Their structures were elucidated by spectral methods including 1D and 2D NMR techniques. Six 2,3-dibenzylbutyrolactone-type lignans were biologically evaluated, and two of them, arctigenin and matairesinol, showed potent activity to suppress NO production in vitro in LPS-activated macrophages of SD rat.

Lignans↗