Biomedical subjects

Bing Li

Publications and source records attributed to Bing Li.

At least 55 records · Page 3Linked to original sources

PubMed2006

Molecular immune mechanism of C-phycocyanin from Spirulina platensis induces apoptosis in HeLa cells in vitro.

C-phycocyanin (C-PC), a water-soluble protein pigment, isolated from Spirulina platensis, is of great importance because of its various medical and pharmacological properties. In the present study, we first investigated the effect of highly purified C-PC on growth and proliferation of HeLa cells in vitro. The results indicated that there was a significant decrease in the number of cells that survived for HeLa cells treated with C-PC compared with control cells untreated with C-PC. Further electron-microscopic studies revealed that C-PC could induce characteristic apoptotic features, including cell shrinkage, membrane blebbing, microvilli loss, chromatin margination and condensation into dense granules or blocks. Agarose electrophoresis of genomic DNA of HeLa cells treated with C-PC showed fragmentation pattern (DNA ladder of oligomers of 180-200 bp) typical for apoptotic cells. Flow-cytometric analysis of HeLa cells treated with different concentrations of C-PC demonstrated an increasing percentage of cells in sub-G0/G1 phase. In addition, we found that C-PC could promote the expression of Fas and ICAM-1 (intercellular cell-adhesion molecule 1) protein, while it held back the Bcl-2 (B-cell lymphocytic-leukaemia proto-oncogene 2) protein expression. This suggested that C-PC could induce the activation of pro-apoptotic gene and downregulation of anti-apoptotic gene expression and then facilitate the transduction of tumoural apoptosis signals that resulted in the apoptosis of HeLa cells in vitro. Caspases 2, 3, 4, 6, 8, 9, and 10 were activated in C-PC-treated HeLa cells, which suggested that C-PC-induced apoptosis was caspase-dependent. C-PC treatment of HeLa cells also resulted in release of cytochrome c from the mitochondria into the cytosol that was related to apoptosis of C-PC-treated HeLa cells.

Apoptosis↗

PubMed2006

Expression of Tim-3 is transiently increased before development of anterior chamber-associated immune deviation.

PURPOSE: To assess the expression of T-cell immunoglobulin- and mucin-domain-containing molecule 3 (Tim-3) in the spleens of BALB/c mice undergoing anterior chamber-associated immune deviation (ACAID). METHODS: ACAID was generated after intracameral (i.c.) injection of ovalbumin (OVA) into BALB/c mice and evaluated by assessing the delayed-type hypersensitivity (DTH) response following a subsequent subcutaneous (s.c.) injection of OVA emulsified in complete Freund's adjuvant (CFA) on Days 0, 3, 7, 14, 21 and 28. Tim-3 mRNA levels were detected using real-time RT-PCR, and the frequency of CD4+Tim-3+ T cells in splenocytes as well as the coexpression of Tim-3 with CD25 on CD4+ T cells were assessed by flow cytometry. RESULTS: A significantly suppressed DTH response was observed on Days 7, 14, 21, and 28, but not on Days 0 and 3 during the development of ACAID. The levels of Tim-3 mRNA and the frequency of CD4+CD25+Tim-3+ T cells in the splenocytes reached a peak on Day 3, declined on Day 7, and returned to basal levels thereafter. CONCLUSIONS: A transient upregulation of Tim-3 expression was observed in the early stage of ACAID, suggesting its possible involvement in the development of ACAID.

Animals↗

PubMed2006

Real-time PCR quantitation of subtype C HIV DNA in a Zambian discordant couple cohort.

To study the viral sequence diversity that is characteristic of HIV infection, PCR amplification and sequencing of viral genes is an essential step. However, a limitation of traditional PCR methods is that one viral target may be preferentially amplified over another when multiple sequences are present. This presents a particular problem when conclusions about diversity are made from one or only a few PCRs. One way to avoid resampling is to perform a large number of PCR amplifications on a single template; however, this requires that extensive dilution series be carried out on each patient sample to identify the appropriate concentration of input DNA. Here we describe the development and implementation of a quantitative real-time PCR (qPCR) method that detects a short sequence in gag and is optimized to detect subtype C HIV sequences. The standard curve was externally validated using two chronically infected cell lines carrying a known number of HIV copies per genome, and this assay yielded reproducible and accurate measurements on patient DNA samples over a wide range of input targets. The qPCR assay results were consistent with those obtained by the traditional limiting dilution method yet entailed only a fraction of the time and reagents required for the latter. This robust and quantitative real-time assay can be used to ensure that each viral sequence obtained through PCR represents a single template for studies in which the diversity of the entire population must be accurately portrayed, and can readily be applied to other research settings and viral subtypes.

Cohort Studies↗

PubMed2006

Evidence for potent autologous neutralizing antibody titers and compact envelopes in early infection with subtype C human immunodeficiency virus type 1.

Information about neutralizing antibody responses in subtype C-infected individuals is limited, even though this viral subtype causes the majority of AIDS cases worldwide. Here we compared the course and magnitude of the autologous neutralizing antibody (NAb) response against viral envelope (Env) glycoproteins present during acute and early infection with subtypes B and C human immunodeficiency virus type 1 (HIV-1). NAb responses were evaluated in 6 subtype B-infected and 11 subtype C-infected subjects over a mean evaluation period of 25 months using a pseudovirus reporter gene assay. All subjects in the C cohort were infected through heterosexual contact, while five of the six subjects in the B cohort were infected via male-to-male contact. The kinetics and magnitude of the NAb responses varied among subjects in the B and C cohorts; however, the median 50% inhibitory concentration (IC(50) titer) reached by antibody in the plasma of subtype C-infected subjects, overall, was 3.5-fold higher than in the subtype B-infected subjects (P = 0.06). The higher titers of NAbs in the C cohort were associated with viruses having significantly shorter amino acid length (P = 0.002) in the V1 to V4 region of the surface Env glycoprotein, gp120, compared to the B cohort. Despite the potency of the autologous subtype C NAb response, it was not directed against cross-neutralizing epitopes. These data demonstrate that subtype C Envs elicit a potent yet restricted NAb response early in infection that frequently reaches IC(50) titers in excess of 1:1,000 and suggest that clade-specific differences may exist in Env immunogenicity or susceptibility to neutralization.

Acquired Immunodeficiency Syndrome↗

PubMed2006

CD4+PD-1+ T cells acting as regulatory cells during the induction of anterior chamber-associated immune deviation.

PURPOSE: To study the expression and functional characteristics of programmed death-1 (PD-1) and its ligands in the spleens of mice undergoing anterior chamber-associated immune deviation (ACAID). METHODS: ACAID was induced in BALB/c mice by intracameral injection of ovalbumin (OVA). The expression of PD-1 and its ligands in the spleens of ACAID mice was determined by quantitative real-time PCR, Western blotting, and flow cytometry. In vitro proliferation assays, enzyme-linked immunosorbent assays, and adoptive transfer assays were used to investigate the functional characteristics of splenic CD4+PD-1+ T cells of ACAID mice. RESULTS: Both mRNA and protein of PD-1, PD-L1, and PD-L2 were markedly upregulated in the spleens of ACAID mice compared with controls. CD4+PD-1+ T cells from ACAID mice produced large amounts of IL-10 and exhibited in vitro antigen-specific suppressive activity. CD4+PD-1+ T cells from ACAID mice were able to significantly inhibit the antigen-specific, delayed-type hypersensitivity response when adoptively transferred to naive mice. CONCLUSIONS: CD4+PD-1+ T cells from ACAID mice, as regulatory cells, are involved in the induction of antigen-specific suppression in association with enhanced expression of IL-10. CD4+PD-1+ T cells in the murine spleen may represent a substantial population of regulatory T cells possibly responsible for the induction of ACAID after intracameral injection of antigen.

Adoptive Transfer↗

PubMed2006

[On-line method for measurement of the carbon isotope ratio of atmospheric methane and its application to atmosphere of Yakela condensed gas field].

An on-line method for measurement of the 13C/12C ratio of methane by a gas chromatography/high-temperature conversion/ isotope ratio mass spectrometry (GC/C/MS) technique was developed. This method is less laborious, more rapid (45 min), of high precision (+/- 0.4 x 10(-3)) and by using a small amount of sample (about 200 mL of atmosphere). Its application to isotopic characterization, and hence methane source identification, was demonstrated by examination of atmosphere sample collected in Yakela condensed gas field, China. The average 13C/12C ratio of atmospheric methane in Yakela field was -45.0 x 10(-3) heavier by 1.2 x 10(-3) -2.0 x 10(-3) than the global average. This is caused by seepage and diffusing of methane from Yakela condensed gas reservoir. The concentrations of atmospheric methane in daytimes are found to be lower than those in nighttimes, and the corresponding 13C/12C ratios in daytimes are lighter compared to those in nighttimes, a phenomena probably caused by the fact that a small part of methane from Yakela condensate reservoir is consumed in soil's surface under sunlight.

Air↗

PubMed2006

Diagnosis and management of extrahepatic portal vein aneurysm: a case report.

BACKGROUND: Extrahepatic portal vein aneurysm is a rare clinical entity with no more than 50 reported cases in the English literature. This study was to elucidate the procedures used in the diagnosis and management of portal vein aneurysm. METHOD: The clinical data of a patient with extrahepatic portal vein aneurysm were analyzed. RESULTS: Extrahepatic portal vein aneurysm associated with portal hypertension and splenomegaly was diagnosed by color Doppler ultrasonography (US), computed tomography (CT), magnetic resonance angiography (MRA) and angiography (indirect portography). Splenectomy and surgical shunt (splenorenal shunt) were performed. No hepatic encephalopathy and variceal bleeding occurred after the operation except mild pancreatic leakage caused by partial pancreatic tail resection. The patient recovered well. CONCLUSIONS: Extrahepatic portal vein aneurysm can be evaluated by US, CT, MRA, and angiography for optimum conservative or surgical management.

Aneurysm↗

PubMed2006

Anticoagulant property of a semi-synthesized sodium beta-1,4-glucan sulfate.

AIM: To investigate the anticoagulant efficacy and mechanism of a semi-synthesized sodium beta-1,4-glucan sulfate (Na-MCS). METHODS: Anticoagulant activity was evaluated by means of coagulation assays in comparison with heparin. The anticoagulant mechanism of Na-MCS was disclosed by inhibitory analysis of the activities of coagulation factors using chromogenic substrates. RESULTS: 0.6 microg x mL(-1) Na-MCS could significantly prolong APTT and TT, but has less effect on PT at an even higher concentration. The dosage of Na-MCS required to double APTT of normal human plasma was 0.7 microg x mL(-1), lower than that of heparin with the activity of 150 u x mg(-1). CONCLUSION: Na-MCS represented a potent anticoagulation activity in vitro, which matched the efficacy of heparin in a certain range of concentrations. Na-MCS exhibited anticoagulant activity due to inhibition of the coagulation factors IIa and Xa by the mediation of anti-thrombin AT-III.

Anticoagulants↗

PubMed2006

[An epidemiological survey on the psychological stress status for students in 13 Chinese colleges].

OBJECTIVE: To explore the main sources causing stress among Chinese college students and its distribution. METHODS: A clustered random sampling method was conducted to perform the questionnaire on psychological stress among 2007 students selected from 13 universities. RESULTS: The main sources of psychological stress on college students regarding learning task, college environment, job-seeking, interpersonal relationship and emotional disorders. 49.3% of the population experienced mild level of psychological stress, 8.4% belonged to critical groups who experienced higher levels of stress,while 0.3% experienced severe level of stress. Sophomores and juniors were under more stressful situation than freshmen and senior students, while female students felt more stressful on learning and job-seeking than males. Male students felt more stressful caused by their families, health status, love affairs, social adaptation and frustration than females. Students from countryside were under more stress than those coming from urbans. Students from ordinary universities felt more stressed than those from famous universities and students from western areas were under more stress than those from the coastal areas. CONCLUSION: Stress had become a severe problem influencing the mental health development among college students. The problem needs to be addressed accordingly.

China↗

PubMed2006

[Effect of allitridum on expression of the gamma-glutamyl-cysteine synthetase in rat lung epithelial L2 cells].

OBJECTIVE: To study the effects of allitridum on the antioxidative capability of rat lung epithelial L2 cells (CCL-149 cell line) by observing the changes of glutathione (GSH), malondialdehyde (MDA) content, and the expressing level of gamma-glutamyl-cysteine synthetase (gamma-GCS) protein. METHODS: The cell viability of CCL-149 cells treated with allitridum was detected by MTT assay. CCL-149 cells were incubated with 0, 0.1, 1.0, 5.0 microg/ml of allitridum for 6, 12, 24, 48 h. After treatment, GSH content and MDA formation were measured by spectrophotometric assay, and the gamma-GCS protein was semi-quantified by Western blot. RESULTS: Allitridum (0.1, 1.0, 5.0 microg/ml) showed no side effects on cell growth (P > 0.05). Treatment with allitridum increased GSH levels and decreased MDA formation in CCL-149, the most significant time being incubation at 24 h. The GSH content were (13.34 +/- 0.62), (27.67 +/- 2.39), (29.54 +/- 0.71), (30.25 +/- 1.05) mg/g prot, and the MDA content were (1.25 +/- 0.08), (0.90 +/- 0.06), (0.84 +/- 0.06), (0.81 +/- 0.02) nmol/mg prot when CCL-149 cells were treatment with 0, 0.1, 1.0, 5.0 microg/ml of allitridum for 24 h, respectively. The effect showed no dose dependent effects (P > 0.05). After 6, 12, 24 h incubation, the expression of gamma-GCS protein was increased as compared to the control cells (t = 2.82 - 9.92, P < 0.05). CONCLUSION: Allitidum may increase the antioxidative ability of CCL-149 cells by increasing the expression of gamma-GCS protein and the content of GSH.

Allyl Compounds↗

PubMed2006

[Effects of sodium arsenite on catalase in human keratinocytes].

OBJECTIVE: To evaluate the effects of sodium arsenite on the activity, the mRNA and the protein expression of CAT in human keratinocyte cell line (HaCaT). METHODS: The activity of catalase (CAT) was detected by ultraviolet direct velocity assay. RT-PCR was used to detect the mRNA expression of CAT and Western blotting was conducted to detect the protein expression of CAT. RESULTS: If the cells were treated with higher than 5.0 micromol/L sodium arsenite, the activity, mRNA and protein expression of CAT were decreased significantly and in a dosage dependent fashion (P < 0.05). CONCLUSION: CAT is inhibited by sodium arsenite in the transcription, translation and activity levels.

Arsenites↗

PubMed2006

Current research problems of chronic arsenicosis in China.

Chronic arsenicosis is a newly-emerged public-health issue in China and many other Asian countries. Over 200 million people are estimated to be at the risk of high arsenic exposure from drinking-water in the Asian region. To protect people from the hazards of chronic arsenic poisoning, the Chinese Government has been providing low-arsenic drinking-water to some seriously-affected rural areas, such as Inner Mongolia autonomous province. Results of follow-up studies showed that both the average values of arsenic, including inorganic arsenic (iAs), monomethylated arsenic, dimethylated arsenic and trimethylated arsenic, and 8-hydroxydeoxyguanine in urine, decreased significantly after drinking low-arsenic water for one year, and arsenic-specific skin lesions also improved to some extent. However, a five-year follow-up study showed no more significant improvement of skin lesions, while the potential risk of arsenic-induced cancers after cutting off high-arsenic exposure was still uncertain and indefinite. The susceptibility of children compared to adults to chronic arsenic exposure and the need to re-evaluate the appropriate standard of arsenic in drinking-water were also discussed in this paper.

Adolescent↗

PubMed2005

Preferential occupancy of histone variant H2AZ at inactive promoters influences local histone modifications and chromatin remodeling.

The yeast histone variant H2AZ (Htz1) is implicated in transcription activation, prevention of the ectopic spread of heterochromatin, and genome integrity. Our genome-wide localization analysis revealed that Htz1 is widely, but nonrandomly, distributed throughout the genome in an SWR1-dependent manner. We found that Htz1 is enriched in intergenic regions compared with coding regions. Its occupancy is inversely proportional to transcription rates and the enrichment of the RNA polymerase II under different growth conditions. However, Htz1 does not seem to directly regulate transcription repression genome-wide; instead, the presence of Htz1 under the inactivated condition is essential for optimal activation of a subset of genes. In addition, Htz1 is not generally responsible for nucleosome positioning, even at those promoters where Htz1 is highly enriched. Finally, using a biochemical approach, we demonstrate that incorporation of Htz1 into nucleosomes inhibits activities of histone modifiers associated with transcription, Dot1, Set2, and NuA4 and reduces the nucleosome mobilization driven by chromatin remodeling complexes. These lines of evidence collectively suggest that Htz1 may serve to mark quiescent promoters for proper activation.

Chromatin Assembly and Disassembly↗

PubMed2005

GATA-3 expression in the development of anterior chamber associated immune deviation.

BACKGROUND: Anterior chamber associated immune deviation (ACAID) is characterized by a Th2 cell response. GATA-3 has been shown to be necessary for the activation of Th2 cells. This study was designed to examine the expression of GATA-3 in the development of ACAID. METHODS: ACAID was induced by injection of 50 microg interphotoreceptor retinoid binding protein (IRBP) into the anterior chamber (AC) of Wistar rats. Delayed-type hypersensitivity (DTH) was evaluated on day 3, 7, 14, 21, 28 after IRBP inoculation. GATA-3 expression was detected using immunohistochemical staining. The expression of GATA-3 mRNA at different time points after AC injection of IRBP was assayed by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: A significant DTH reaction was observed in Wistar rats on day 3 and 5 after IRBP inoculation. The DTH reaction was decreased 7 days after IRBP inoculation. GATA-3 expression was weak at both mRNA and protein levels in the normal spleen, but was significantly increased on day 5, 7, 14, and 21 after AC injection of IRBP. CONCLUSION: The expression of GATA-3 is increased during ACAID, suggesting that GATA-3 may be involved in the development of ACAID.

Animals↗

PubMed2005

Chemoenzymatic synthesis of HIV-1 V3 glycopeptides carrying two N-glycans and effects of glycosylation on the peptide domain.

[structure: see text] A highly efficient chemoenzymatic synthesis of HIV-1 V3 domain glycopeptides carrying two N-linked core tri- and pentasaccharides was achieved. The synthesis consisted of two key steps: a solid-phase synthesis of the cyclic, 47-mer V3 domain peptide containing two GlcNAc residues and a novel endoglycosidase-catalyzed transglycosylation that simultaneously added two N-glycan moieties to the peptide precursor from the oligosaccharide oxazoline donor substrates. The availability of the synthetic glycopeptides allowed the probing of the effects of glycosylation on the HIV-1 V3 domain. It was demonstrated that glycosylation influenced the global conformations of the V3 domain and provided protection of the V3 domain against protease digestion.

Amino Acid Sequence↗

PubMed2005

Histone H3 methylation by Set2 directs deacetylation of coding regions by Rpd3S to suppress spurious intragenic transcription.

Yeast Rpd3 histone deacetylase plays an important role at actively transcribed genes. We characterized two distinct Rpd3 complexes, Rpd3L and Rpd3S, by MudPIT analysis. Both complexes shared a three subunit core and Rpd3L contains unique subunits consistent with being a promoter targeted corepressor. Rco1 and Eaf3 were subunits specific to Rpd3S. Mutants of RCO1 and EAF3 exhibited increased acetylation in the FLO8 and STE11 open reading frames (ORFs) and the appearance of aberrant transcripts initiating within the body of these ORFs. Mutants in the RNA polymerase II-associated SET2 histone methyltransferase also displayed these defects. Set2 functioned upstream of Rpd3S and the Eaf3 methyl-histone binding chromodomain was important for recruitment of Rpd3S and for deacetylation within the STE11 ORF. These data indicate that Pol II-associated Set2 methylates H3 providing a transcriptional memory which signals for deacetylation of ORFs by Rpd3S. This erases transcription elongation-associated acetylation to suppress intragenic transcription initiation.

Acetylation↗

PubMed2005

The proteasome regulatory particle alters the SAGA coactivator to enhance its interactions with transcriptional activators.

Promoter recruitment of the Saccharomyces cerevisiae SAGA histone acetyltransferase complex is required for RNA polymerase II-dependent transcription of several genes. SAGA is targeted to promoters through interactions with sequence-specific DNA binding transcriptional activators and facilitates preinitiation-complex assembly and transcription. Here, we show that the 19S proteasome regulatory particle (19S RP) alters SAGA to stimulate its interaction with transcriptional activators. The ATPase components of the 19S RP are required for stimulation of SAGA/activator interactions and enhance SAGA recruitment to promoters. Proteasomal ATPases genetically interact with SAGA, and their inhibition reduces global histone H3 acetylation levels and SAGA recruitment to target promoters in vivo. These results indicate that the 19S RP modulates SAGA complex using its ATPase components, thereby facilitating subsequent transcription events at promoters.

Acetylation↗

PubMed2005

In and out: histone variant exchange in chromatin.

Alterations in nucleosome structure affect the accessibility of the DNA and can generate specialized domains of chromatin in the genome. Such changes can be introduced by posttranslational modifications of histones, by chromatin remodeling, or by the incorporation of variants of H2A and H3 into nucleosomes. In contrast to the canonical histones, which are deposited behind the replication fork during S phase, histone variants are incorporated in a process that is independent of DNA replication. Recent studies have shown that distinct multiprotein complexes are responsible for the targeted deposition of histone variants at active genes, centromeres and silent loci. The incorporation of histone variants most probably has epigenetic consequences and contributes to architectural changes in chromosomes.

Amino Acid Sequence↗