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Biomedical subjects

Bing Li

Publications and source records attributed to Bing Li.

At least 73 records · Page 4Linked to original sources
PubMed2005

The early embryo loss caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin may be related to the accumulation of this compound in the uterus.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a reproductive and developmental toxicant that can alter endocrine status, leading to decreased fertility and altered embryonic development; however, there are limited reports on TCDD toxicity during early pregnancy. In the present study, pregnant and pseudopregnant NIH mice were exposed to TCDD orally (2, 50 and 100 ng/kg body weight) during early gestation (days 1-8), pre-implantation stages (days 1-3), and peri-implantation to early post-implantation stages (days 4-8). TCDD concentration in uterus, liver, kidney, brain and fat on day 9 of pregnancy was monitored by an aryl hydrocarbon receptor (Ah receptor, AhR)-mediated LacZ reporter system in yeast. Results showed that the number of implanted embryos was significantly reduced on day 9 of gestation by 50 and 100 ng/kg TCDD exposure. The number of implantation sites was lower for animals exposed to TCDD on days 1-3 versus those exposed during days 4-8. Decidualization in pseudopregnant mice was also inhibited by TCDD exposure. TCDD concentrations as low as 2 ng/kg significantly decreased serum progesterone levels but had no effect on serum estradiol. TCDD level in the uterus was equal to levels in the liver, but lower than the fat tissue. These results suggest that TCDD sensitivity might be attributed its local accumulation in the uterus.

Animals↗
PubMed2005

Effects of CD59 on antitumoral activities of phycocyanin from Spirulina platensis.

The regulatory effect of phycocyanin (PC) from Spirulina platensis on cluster of differentiation 59 (CD59) gene expression of Hela cells and antitumoral mechanism of PC was investigated in this study. PC was purified by hydroxylapatite (HA) and sephacrylHR-200 gel-filtration columns chromatography. The molecular weight of PC was determined by SDS-PAGE electrophoresis. The CD59 cDNA was inserted into the eukaryotic expression plasmid pALTER-MAX, and the recombinant vector pALTER-MAX-CD59 was successfully constructed. By using cationic liposome (Lipfectamine-2000)-mediated transfection method, the recombinant plasmid pALTER-MAX-CD59 and the selective marker PcDNA were cotransfected into Hela cells and normal Chinese hamster ovary (CHO) cells. Stable positive cell clones were sorted out and disposed with different concentrates of PC. The expression of CD59 protein was determined by in situ hybridization, immunofluorescence and enzyme linked immunosorbent assay (ELISA). In addition, the effect of PC on the proliferation of Hela cells was determined by MTT method and the expression of Fas protein was by immunohistochemistry. Results showed that PC can promote the expression of CD59 protein in Hela cells, hold back it is reproductions of Hela cells, and moreover, a dosage effect was found between them. Namely, with the ascendance of PC concentration, the expression quantities of CD59 protein and apoptosis-inducing Fas protein increased and the multiplication activity of Hela cells declined, whereas PC was of no use to CD59 and Fas protein expression, and reproduction of normal CHO cells as well. Besides an imaginable antitumoral molecular immune mechanism of PC was brought forward and discussed.

Animals↗
PubMed2005

Identification of an E-box motif as a transcriptional repressor element in the proximal promoter region of the GCLC gene in rat lung epithelial L2 cells.

Glutathione (GSH) is a critical antioxidant for protecting the airway epithelium from oxidant injury and its levels are mainly controlled by glutamate-cysteine ligase (GCL), which is the rate-limiting enzyme in GSH synthesis. A full understanding of the gene regulation mechanism of this important enzyme may disclose the role it plays in respiratory diseases. GCL is made up of two differentially regulated subunits, a catalytic or heavy subunit (GCLC) and a modifier or light subunit (GCLM). Many studies in this field led to the findings of important positive regulatory regions of the GCLC promoter. For a detailed analysis of this gene regulation in the respiratory system, we cloned a 1.76-kb 5'-flanking region of the rat GCLC gene, inserted into a luciferase reporter vector. Exonuclease III was used to cut the 5'-flanking region of the rat GCLC gene unidirectionally into deletion mutants of different lengths. Sequential deletion analysis revealed that regions from -403 to -111 and from -705 to -613 are involved in positive regulation and the region from -745 to -705 is involved in negative regulation of the GCL gene in rat lung epithelial L2 cells. Specific proteins binding to these regions were confirmed by electrophoretic mobility-shift assays (EMSAs) and antibody supershift assays. An E-box motif was found in the negative regulatory region -745 to -705. Site-directed mutagenesis proved that the functional element in this negative regulatory region was a putative E-box element. EMSA and supershift assays showed that USF1 and USF2 can specifically bind to the E-box element. Overexpression of USFs in L2 cells led to a decreased activity of the GCLC promoter. Western blotting demonstrated that the expression of GCLC protein was decreased in the retroviral USFs-expressing cells than in nontransfected (no DNA added) cells, suggesting that USF binding to the E-box at -729/-724 serves to trans-repress GCLC gene expression. These findings indicate that the E-box is an important transcriptional suppressor element in the GCLC promoter in rat lung epithelial L2 cells. Inhibition of interaction between the E-box and the USF may provide an effective means of ameliorating oxidant injury of the lung.

5' Flanking Region↗
PubMed2005

Beta-glucan enhances complement-mediated hematopoietic recovery after bone marrow injury.

Myelotoxic injury in the bone marrow (BM) as a consequence of total body irradiation (TBI) or granulocyte colony-stimulating factor (G-CSF) mobilization results in the deposition of iC3b on BM stroma (stroma-iC3b). In the present study, we have examined how stroma-iC3b interacts with hematopoietic progenitor cells (HPCs) and the role of complement (C) and complement receptor 3 (CR3) in BM injury/repair. We demonstrate here that stroma-iC3b tethers HPCs via the inserted (I) domain of HPC complement receptor 3 (CR3, CD11b/CD18, Mac-1). Following irradiation, stroma-iC3b was observed in the presence of purified IgM and normal mouse serum (NMS), but not serum from Rag-2(-/-) mice, implicating a role for antibody (Ab) and the classic pathway of C activation. Furthermore, a novel role for soluble yeast beta-glucan, a ligand for the CR3 lectin-like domain (LLD), in the priming of CR3(+) HPC is suggested. Soluble yeast beta-glucan could enhance the proliferation of tethered HPCs, promote leukocyte recovery following sublethal irradiation, and increase the survival of lethally irradiated animals following allogeneic HPC transplantation in a CR3-dependent manner. Taken together, these observations suggest a novel role for C, CR3, and beta-glucan in the restoration of hematopoiesis following injury.

Animals↗
PubMed2005

Impact of release characteristics of sinomenine hydrochloride dosage forms on its pharmacokinetics in beagle dogs.

AIM: To investigate the effect of release behavior of sustained-release dosage forms of sinomenine hydrochloride (SM.HCl) on its pharmacokinetics in beagle dogs. METHODS: The in vitro release behavior of two SM.HCl dosage forms, including commercial 12-h sustained-release tablets and 24-h sustained-release pellets prepared in our laboratory, was examined. The two dosage forms were orally administrated to beagle dogs, and then the in vivo SM.HCl pharmacokinetics was investigated and compared. RESULTS: The optimal SM.HCl sustained-release formulation was achieved by mixing slow- and rapid-release pellets (9:1, w/w). The SM.HCl release profiles of the sustained-release pellets were scarcely influenced by the pH of the dissolution medium. Release from the 12-h sustained-release tablets was markedly quicker than that from the 24-h sustained-release pellets, the cumulative release up to 12-h was 99.9% vs 68.7%. From a pharmacokinetic standpoint, the 24-h SM.HCl sustained-release pellets had longer tmax and lower Cmax compared to the 12-h sustained-release tablets, the tmax being 2.67+/-0.52 h vs 9.83+/-0.98 h and the Cmax being 1 334.45+/-368.76 ng/mL vs 893.12+/-292.55 ng/mL, respectively. However, the AUC(0-tn) of two SM.HCl dosage forms was comparable and both preparations were statistically bioequivalent. Furthermore, the two preparations had good correlations between SM.HCl percentage absorption in vivo and the cumulative percentage release in vitro. CONCLUSION: The in vitro release properties of the dosage forms strongly affect their pharmacokinetic behavior in vivo. Therefore, managing the in vitro release behavior of dosage forms is a promising strategy for obtaining the optimal in vivo pharmacokinetic characteristics and safe therapeutic drug concentration-time curves.

Administration, Oral↗
PubMed2005

Highly efficient endoglycosidase-catalyzed synthesis of glycopeptides using oligosaccharide oxazolines as donor substrates.

A highly efficient chemoenzymatic synthesis of N-glycopeptides was achieved. It was found that using synthetic oligosaccharide oxazolines, the mimics of the presumed oxazolinium ion intermediate formed in a retaining mechanism of substrate-assisted catalysis, as the donor substrates and GlcNAc-peptides as the acceptors, the endo-beta-N-acetylglucosaminidase (ENGase)-catalyzed transglycosylation gave a high yield (73-82%) of the corresponding glycopeptides in a regio- and stereospecific manner, regardless of the size of the peptide portions. The use of the oligosaccharide oxazolines as donor substrates not only expanded the substrate availability but also led to a substantial enhancement of the synthetic efficiency, compared to the use of natural N-glycans.

Amino Acid Sequence↗
PubMed2005

Crm1-mediated nuclear export of Cdc14 is required for the completion of cytokinesis in budding yeast.

The mitotic exit network (MEN) controls the exit from mitosis in budding yeast. The proline-directed phosphatase, Cdc14p, is a key component of MEN and promotes mitotic exit by activating the degradation of Clb2p and by reversing Cdk-mediated mitotic phosphorylation. Cdc14p is sequestered in the nucleolus during much of the cell cycle and is released in anaphase from the nucleolus to the nucleoplasm and cytoplasm to perform its functions. Release of Cdc14p from the nucleolus during anaphase is well understood. In contrast, less is known about the mechanism by which Cdc14p is released from the nucleus to the cytoplasm. Here we show that Cdc14p contains a leucine-rich nuclear export signal (NES) that interacts with Crm1p physically. Mutations in the NES of Cdc14p allow Clb2p degradation and mitotic exit, but cause abnormal morphology and cytokinesis defects at non-permissive temperatures. Cdc14p localizes to the bud neck, among other cytoplasmic structures, following its release from the nucleolus in late anaphase. This bud neck localization of Cdc14p is disrupted by mutations in its NES and by the leptomycin B-mediated inhibition of Crm1p. Our results suggest a requirement for Crm1p-dependent nuclear export of Cdc14p in coordinating mitotic exit and cytokinesis in budding yeast.

Active Transport, Cell Nucleus↗
PubMed2005

Pattern motion and component motion sensitivity in cat superior colliculus.

Single neurons in the superior colliculus of the cat were tested for their direction-tuning responses to random-line patterns composed of identical short lines moving obliquely to their common orientation. A substantial population of cells responded primarily to the veridical direction of pattern motion while a few were sensitive to the orientation of component lines. Moreover, for most cells, the pattern motion sensitivity decreased when the orientation element was enhanced by elongating the component lines in stimulus. Further analysis found that the initial transient responses after stimulus onset were relatively more sensitive to component motion than the subsequent sustained responses. These findings suggest that the superior colliculus is involved in the higher-order analysis of visual motion so that collicular neurons can signal coherent pattern motion in many cases.

Animals↗
PubMed2005

Molecular recognition by a binary code.

Functional antibodies were obtained from a library of antigen-binding sites generated by a binary code restricted to tyrosine and serine. An antibody raised against human vascular endothelial growth factor recognized the antigen with high affinity (K(D)=60 nM) and high specificity in cell-based assays. The crystal structure of another antigen binding fragment in complex with its antigen (human death receptor DR5) revealed the structural basis for this minimalist mode of molecular recognition. Natural antigen-binding sites are enriched for tyrosine and serine, and we show that these amino acid residues are intrinsically well suited for molecular recognition. Furthermore, these results demonstrate that molecular recognition can evolve from even the simplest chemical diversity.

Amino Acid Sequence↗
PubMed2005

[Experimental study of E-box, a transcriptional suppressor element in gamma-GCS gene].

OBJECTIVE: To validate that the E-box element in the -745-705 region of rat gamma-GCS catalytic subunit gene (GCLC gene), already found to be a negative regulatory region, is an important transcriptional suppressor element. METHODS: Electrophoretic mobility shift assays (EMSA) and antibody supershift assay were used to confirm the specific binding of USF, a transcription factor that binds the regulatory sequence -745 - 705, and E-box element. Rat alveolar epidermal cells of the line CCL-149 were cultured and then divided into 4 groups: group 1 to be transfected with GCLC-Luc, group 2 to be co-transfected with pGCLC-Luc and pCMV-USF1, group 3 to be co-transfected with pGCLC-Luc and pCMV-USF2, and group 4 to be co-transfected with pGCLC-Luc and blank vector pCMV. Recombinant retrovirus vector PLXSN-USF1 and recombinant retrovirus vector PLXSN-USF2 were constructed. Another CCL-149 cells were divided into 4 groups: group A to be infected with recombinant USF1 virus, group B to be infected with recombinant USF2 virus, group C to be infected with blank vector, and group D not to be infected with any plasmid. Western blotting was used to detect the concentrations of GCLC protein. RESULTS: EMSA showed that only the probes with complete E-box element could be bound by the USFs. Supershift assay showed that the transcription factor binding the probe was USF. The luciferase activity of the CCL-149 cells co-transfected with pCMV-USF1/USF2 and GCLC-Luc were decreased by 66.4% and 63.2% respectively in comparison with those transfected with GCLC-Luc only (both P < 0.05) and decreased by 54.5% and 61.1% respectively in comparison with those of the cells of the blank vector group (both P < 0.05). Western blotting showed that the expression of GCLC protein of the CCL-149 cells transfected with PLXSN-USF1 and PLXSN-USF2 were decreased in comparison with that of the control cells. CONCLUSION: The interaction between E-box and USF suppresses the expression of GCLC gene. E-box is an important transcriptional suppressor element of gamma-GCS gene.

Animals↗
PubMed2005

Solubility of disulfide-bonded proteins in the cytoplasm of Escherichia coli and its "oxidizing" mutant.

AIM: To study the influence of redox environment of Escherichia coli (E. coli) cytoplasm on disulfide bond formation of recombinant proteins. METHODS: Bovine fibroblast growth factor (BbFGF) was selected as a model of simple proteins with a single disulfide bond and free cysteines. Anti-HBsAg single-chain Fv (HBscFv), an artificial multidomain protein, was selected as the model molecule of complex protein with 2 disulfide bonds. A BbFGF-producing plasmid, pJN-BbFGF, and a HBscFv producing-plasmid, pQE-HBscFv, were constructed and transformed into E. coli strains BL21(DE3) and M15(pREP4) respectively. At the same time, both plasmids were transformed into a reductase-deficient host strain, E. coli Origami(DE3). The 4 recombinant E. coli strains were cultured and the target proteins were purified. Solubility and bioactivity of recombinant BbFGF and HBscFv produced in different host strains were analyzed and compared respectively. RESULTS: All recombinant E. coli strains could efficiently produce target proteins. The level of BbFGF in BL21(DE3) was 15-23% of the total protein, and was 5-10% in Origami (DE3). In addition, 65% of the BbFGF produced in BL21(DE3) formed into inclusion body in the cytoplasm, and all the target proteins became soluble in Origami(DE3). The bioactivity of BbFGF purified from Origami(DE3) was higher than its counterpart from BL21(DE3). The ED(50) of BbFGF from Origami(DE3) and BL21(DE3) was 1.6 microg/L and 2.2 microg/L, respectively. Both HBscFv formed into inclusion body in the cytoplasm of M15(pQE-HBscFv) or Origami(pQE-HBscFv). But the supernatant of Origami(pQE-HBscFv) lysate displayed weak bioactivity and its counterpart from M15(pQE-HBscFv) did not display any bioactivity. The soluble HBscFv in Origami(pQE-HBscFv) was purified to be 1-2 mg/L and its affinity constant was determined to be 2.62 x 10(7) mol/L. The yield of native HBscFv refolded from inclusion body in M15(pQE-HBscFv) was 30-35 mg/L and the affinity constant was 1.98 x 10(7) mol/L. There was no significant difference between the bioactivity of HBscFvs refolded from the inclusion bodies produced in different host strains. CONCLUSION: Modification of the redox environment of E. coli cytoplasm can significantly improve the folding of recombinant disulfide-bonded proteins produced in it.

Animals↗
PubMed2005

Histones: should I stay or should I go?

A report on the American Society for Biochemistry and Molecular Biology symposium 'Transcriptional Regulation by Chromatin and RNA polymerase II', Lake Tahoe, USA, 29 October-1 November 2004.

Chromatin↗
PubMed2005

The mammalian YL1 protein is a shared subunit of the TRRAP/TIP60 histone acetyltransferase and SRCAP complexes.

The multiprotein mammalian TRRAP/TIP60-containing histone acetyltransferase (HAT) complex performs critical functions in a variety of cellular processes including transcriptional activation, double strand DNA break repair, and apoptosis. We previously isolated the TRRAP/TIP60 complex from HeLa cells (Cai, Y., Jin, J., Tomomori-Sato, C., Sato, S., Sorokina, I., Parmely, T. J., Conaway, R. C., and Conaway, J. W. (2003) J. Biol. Chem. 278, 42733-42736). Analysis of proteins present in preparations of the TRRAP/TIP60 complex led to the identification of several new subunits, as well as several potential subunits including the YL1 protein. Here we present evidence that the YL1 protein is a previously unrecognized subunit of the TRRAP/TIP60 HAT complex. In addition, we present evidence that YL1 is also a component of a novel mammalian multiprotein complex that includes the SNF2-related helicase SRCAP and resembles the recently described Saccharomyces cerevisiae SWR1 chromatin remodeling complex. Taken together, our findings identify the YL1 protein as a new subunit of the TRRAP/TIP60 HAT complex, and they suggest that YL1 plays multiple roles in chromatin modification and remodeling in cells.

Acetyltransferases↗
PubMed2005

Clinical patterns and characteristics of uveitis in a tertiary center for uveitis in China.

PURPOSE: To address the clinical pattern and characteristics of uveitis in a tertiary center for uveitis in China and compare the similarity and difference in the distribution of uveitis entities between China and other countries. METHODS: A retrospective study was performed on the patients with uveitis referred to the Zhongshan Ophthalmic Center from January 1996 to December 2003. The clinical data including category, etiology, gender, and the age of the patients at uveitis presentation were analyzed and compared with studies published previously from other countries. RESULTS: There were 902 male and 850 female patients in our series. The mean age of these patients at uveitis presentation was 33.8 +/- 16.5 years. Anterior uveitis (800, 45.6%) was the most common anatomical entity, followed by panuveitis (727, 41.5%), posterior uveitis (119, 6.8%), and intermediate uveitis (106, 6.1%). Further classification with the etiology criteria revealed 16 entities in anterior uveitis, with idiopathic anterior uveitis being the most common entity (473, 27.0%). Twelve entities were identified in panuveitis, of which Behçet disease (289, 16.5%) and Vogt-Koyanagi-Harada (VKH) syndrome (278, 15.9%) were the predominant ones. No specific entity was recognized in the intermediate uveitis group. Although a number of specific entities were identified in posterior uveitis, toxoplasmosis was noted in only two patients in this group. CONCLUSIONS: Idiopathic anterior uveitis, Behçet disease, and VKH syndrome are the most common entities of uveitis in China. Ocular toxoplasmosis, ocular histoplasmosis, and birdshot retinochoroidopathy are less common or absent in China.

Adolescent↗
PubMed2005

An artificial somatic-autonomic reflex pathway procedure for bladder control in children with spina bifida.

PURPOSE: Neurogenic bladder is a major problem for children with spina bifida. Despite rigorous pharmacological and surgical treatment, incontinence, urinary tract infections and upper tract deterioration remain problematic. We have previously demonstrated the ability to establish surgically a skin-central nervous system-bladder reflex pathway in patients with spinal cord injury with restoration of bladder storage and emptying. We report our experience with this procedure in 20 children with spina bifida. MATERIALS AND METHODS: All children with spina bifida and neurogenic bladder underwent limited laminectomy and a lumbar ventral root (VR) to S3 VR microanastomosis. The L5 dorsal root was left intact as the afferent branch of the somatic-autonomic reflex pathway after axonal regeneration. All patients underwent urodynamic evaluation before and after surgery. RESULTS: Preoperative urodynamic studies revealed 2 types of bladder dysfunction- areflexic bladder (14 patients) and hyperreflexic bladder with detrusor external sphincter dyssynergia (6). All children were incontinent. Of the 20 patients 17 gained satisfactory bladder control and continence within 8 to 12 months after VR microanastomosis. Of the 14 patients with areflexic bladder 12 (86%) showed improvement. In these cases bladder capacity increased from 117.28 to 208.71 ml, and mean maximum detrusor pressure increased from 18.35 to 32.57 cm H2O. Five of the 6 patients with hyperreflexic bladder demonstrated improvement, with resolution of incontinence. Urodynamic studies in these cases revealed a change from detrusor hyperreflexia with detrusor external sphincter dyssynergia and high detrusor pressure to nearly normal storage and synergic voiding. In these cases mean bladder capacity increased from 94.33 to 177.83 ml, and post-void residual urine decreased from 70.17 to 23.67 ml. Overall, 3 patients failed to exhibit any improvement. CONCLUSIONS: The artificial somatic-autonomic reflex arc procedure is an effective and safe treatment to restore bladder continence and reverse bladder dysfunction for patients with spina bifida.

Adolescent↗
PubMed2005

Bone marrow cells contribute to regeneration of damaged glomerular endothelial cells.

BACKGROUND: There is accumulating evidence that adult bone marrow (BM) cells show unexpected plasticity, and can differentiate into a wide range of specialized cells. In the case of intrinsic renal glomerular cells, BM-derived cells have been reported to differentiate into both mesangial cells and podocytes. However, there is controversy on recruitment of glomerular endothelial cells, although endothelial cells in other tissues are known to be recruited from the BM. METHODS: Sprague-Dawley (SD) rats and SD rats made chimeric by transplantation of bone marrow cells from enhanced green fluorescent protein (EGFP) transgenic littermate rats, were injected with anti-Thy-1.1 antibody, followed by unilateral nephrectomy (1-kidney model). Chimeric rats used in 1-kidney model were sacrificed for histologic examination at weeks 2, 4, 8, and 11. We examined isolated glomeruli and frozen sections of kidneys from rats of each group at weeks 2 and 11 by confocal laser scan microsopy (CLSM), both immunohistologically and three dimensionally. RESULTS: In the 1-kidney group, using chimeric rats transplanted with EGFP(+) bone marrow cells, most rats died, presumably of uremia, after 8 to 11 weeks. A CLSM study using isolated glomeruli and frozen sections of kidneys revealed that bone marrow-derived PECAM-1(+), RECA-1(+) cells, and OX-7(+) cells contributed to the structural support for the glomerular capillaries during the chronic course. Global glomerular sclerotic lesions and diffuse tubular atrophic changes, with interstitial cell infiltration, were remarkable at weeks 8 and 11. CONCLUSION: Bone marrow-derived endothelial progenitor cells participated in glomerular endothelial cell turnover after severe damage. Treatment that could target bone marrow-derived endothelial progenitor cells and promote angiogenesis in regions of progressive glomerular lesions may be a promising therapeutic approach for preventing end-stage renal disease.

Animals↗
PubMed2005

Pretreatment of coking wastewater using anaerobic sequencing batch reactor (ASBR).

A laboratory-scale anaerobic sequencing batch reactor (ASBR) was used to pretreat coking wastewater. Inoculated anaerobic granular biomass was acclimated for 225 d to the coking wastewater, and then the biochemical methane potential (BMP) of the coking wastewater in the acclimated granular biomass was measured. At the same time, some fundamental technological factors, such as the filling time and the reacting time ratio (t(f)/t(r)), the mixing intensity and the intermittent mixing mode, that affect anaerobic pretreatment of coking wastewater with ASBR, were evaluated through orthogonal tests. The COD removal efficiency reached 38%-50% in the stable operation period with the organic loading rate of 0.37-0.54 kg COD/(m(3).d) at the optimum conditions of t(f)/t(r), the mixing intensity and the intermittent mixing mode. In addition, the biodegradability of coking wastewater distinctly increased after the pretreatment using ASBR. At the end of the experiment, the microorganism forms on the granulated sludge in the ASBR were observed using SEM (scanning electron microscope) and fluoroscope. The results showed that the dominant microorganism on the granular sludge was Methanosaeta instead of Methanosarcina dominated on the inoculated sludge.

Bacteria, Anaerobic↗