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Biomedical subjects

Bing Liu

Publications and source records attributed to Bing Liu.

At least 55 records · Page 3Linked to original sources
PubMed2005

Controllable growth of well-defined regular multiporphyrin array nanocrystals at the water-chloroform interface.

On the basis of the coordination geometry of metal ions, regular cubic, clubbed, and wirelike nanocrystals of Cd(2+)-/PtCl(6)(2-)-mediated, and Hg(2+)-/Ag(+)-/PtCl(4)(2-)-mediated multiporphyrin arrays have been grown at the water-chloroform interface. The nanocrystal growth process was monitored by the transmission electron microscopy (TEM), which revealed (1) an intrinsic rule for coordination polymers, that is, the geometries of metal ions (as connects for the coordination polymers) dominate the frameworks of the related polymeric nanocrystals, and (2) one kind of intuitive nanocrystal growth processes at the interfaces. Both electron diffraction and X-ray diffraction patterns indicated the formation of well-defined nanocrystals. It was found that single-/microcrystals were formed at first, and then they grew into polycrystals. The nanocrystal layer was transferred onto Si and quartz substrate surfaces by the Langmuir-Blodgett method, with its composition analyzed by X-ray photoelectron spectroscopy as well as the arrangement of porphyrin macrocycles in the nanocrystals by UV-vis absorption spectroscopy.

Journal Article↗
PubMed2005

Nanometer-scale optical imaging of epitaxially grown GaN and InN islands using apertureless near-field microscopy.

Nanometer-scale chemical imaging of epitaxially grown gallium nitride (GaN) and indium nitride (InN) islands is performed using scattering-type apertureless near-field scanning optical microscopy (ANSOM). The scattering of 633 nm laser radiation is modulated by an oscillating metallic probe, and the scattered radiation is detected by homodyne amplification, followed by high-harmonic demodulation, yielding optical near-field scattering maps with a spatial resolution better than 30 nm. The image contrast between InN and GaN, and the tip-sample distance dependence, can be qualitatively explained by a simple dipole-coupling model. The ANSOM images of InN and GaN also show structures that are absent in the topographic counterpart, and these substructures are explained by the variations of the local dielectric environment of InN and GaN.

Journal Article↗
PubMed2005

SARS-CoV protease inhibitors design using virtual screening method from natural products libraries.

Two natural products databases, the marine natural products database (MNPD) and the traditional Chinese medicines database (TCMD), were used to find novel structures of potent SARS-CoV protease inhibitors through virtual screening. Before the procedure, the databases were filtered by Lipinski's ROF and Xu's extension rules. The results were analyzed by statistic methods to eliminate the bias in target-based database screening toward higher molecular weight compounds for enhancing the hit rate. Eighteen lead compounds were recommended by the screening procedure. They were useful for experimental scientists in prioritizing drug candidates and studying the interaction mechanism. The binding mechanism was also analyzed between the best screening compound and the SARS protein.

Algorithms↗
PubMed2005

Effects of pertussis toxin on electroacupuncture-produced anti-hyperalgesia in inflamed rats.

Our previous study showed that electroacupuncture (EA) significantly attenuated hyperalgesia in an animal model of persistent inflammatory pain. The present study was designed to show if Gi/o protein is involved in EA-produced anti-hyperalgesia. Spinal Gi/o-protein function was destroyed by intrathecal pretreatment with pertussis toxin (PTX). Seven days after the placement of an intrathecal PE-10 tube, PTX was injected into the intrathecal space of the lumbar spinal cord of rats. Seven days after PTX, complete Freund's adjuvant (CFA) was injected into the plantar surface of one hind paw of the rat to induce hyperalgesia in the injected paw. EA treatment was given at acupoint GB30 immediately post-CFA and then hyperalgesia was assessed by measuring the degree of decreased paw withdrawal latency (PWL) to a noxious thermal stimulus. The results showed that PTX pretreatment prevented EA-produced anti-hyperalgesia in the CFA inflammatory pain model but did not affect either baseline pain threshold or CFA-induced hyperalgesia. The data suggest that EA-produced anti-hyperalgesia is mediated by PTX-sensitive Gi/o proteins and the relevant signaling pathways.

Animals↗
PubMed2005

Construction of a virtual combinatorial library using SMILES strings to discover potential structure-diverse PPAR modulators.

Based on the structural characters of PPAR modulators, a virtual combinatorial library containing 1226,625 compounds was constructed using SMILES strings. Selected ADME filters were employed to compel compounds having poor drug-like properties from this library. This library was converted to sdf and mol2 files by CONCORD 4.0, and was then docked to PPARgamma by DOCK 4.0 to identify new chemical entities that may be potential drug leads against type 2 diabetes and other metabolic diseases. The method to construct virtual combinatorial library using SMILES strings was further visualized by Visual Basic.net that can facilitate the needs of generating other type virtual combinatorial libraries.

Combinatorial Chemistry Techniques↗
PubMed2005

Spinal preprodynorphin mRNA expression in neonatal rats following peripheral inflammation.

Spinal nociceptive neural circuits undergo considerable changes during the postnatal period. This study showed that neonatal rats exhibited earlier upregulation and faster recovery of spinal preprodynorphin (PPD) mRNA than did the adults during complete Freund's adjuvant (CFA)-induced peripheral inflammation. These data suggest that the central nervous systems of neonates and adults respond differently to peripheral noxious inputs, a fact that should be considered when selecting pain treatment strategies for neonate populations.

Aging↗
PubMed2005

Human mesenchymal stem cells inhibit differentiation and function of monocyte-derived dendritic cells.

Mesenchymal stem cells (MSCs), in addition to their multilineage differentiation, have a direct immunosuppressive effect on T-cell proliferation in vitro. However, it is unclear whether they also modulate the immune system by acting on the very first step. In this investigation, we addressed the effects of human MSCs on the differentiation, maturation, and function of dendritic cells (DCs) derived from CD14+ monocytes in vitro. Upon induction with granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4), MSC coculture could strongly inhibit the initial differentiation of monocytes to DCs, but this effect is reversible. In particular, such suppression could be recapitulated with no intercellular contact at a higher MSC/monocyte ratio (1:10). Furthermore, mature DCs treated with MSCs were significantly reduced in the expression of CD83, suggesting their skew to immature status. Meanwhile, decreased expression of presentation molecules (HLA-DR and CD1a) and costimulatory molecules (CD80 and CD86) and down-regulated IL-12 secretion were also observed. In consistence, the allostimulatory ability of MSC-treated mature DCs on allogeneic T cells was impaired. In conclusion, our data suggested for the first time that human MSCs could suppress monocyte differentiation into DCs, the most potent antigen-presenting cells (APCs), thus indicating the versatile regulation of MSCs on the ultimate specific immune response.

Cell Differentiation↗
PubMed2005

The production of synthetic chemodisruptive peptides in planta disrupts the establishment of cyst nematodes.

Root exudates from transgenic potato plants expressing a chemoreception-disruptive peptide inhibit acetylcholinesterase by up to 63 +/- 3%. This inhibition correlates strongly with the efficacy of the exudates as a presoak solution for infective juveniles of Heterodera glycines that leads to reduced root invasion. The establishment of developing Globodera pallida at 21 days post-infection in these transgenic plants was also suppressed in containment trials. Relative to controls, the best line showed a 47 +/- 5% reduction in developing females and had 188 +/- 25% more undeveloped infective juveniles. This suggests that disorientation of chemoreception occurs after initial root invasion. Line (e) showed the highest level of resistance with 61 +/- 4% in glasshouse trials conducted over a 9-week period. This result represents the combined effect on the number of cysts produced and the number of eggs each cyst contains. The level of control shown to saccate females was consistent in both the 21-day and 9-week post-infection studies. Another chemoreception-disruptive peptide, that binds to nematode nicotinic receptors in cholinergic neurones, provided a 52.6 +/- 1% reduction in the number of nematodes able to establish in transgenic hairy roots that expressed the peptide. This confirms that both chemoreception-disruptive peptides have efficacy in suppressing parasitism by cyst nematodes when expressed in planta at low concentrations.

Journal Article↗
PubMed2005

Prediction of death for extremely low birth weight neonates.

OBJECTIVE: To compare multiple logistic regression and neural network models in predicting death for extremely low birth weight neonates at 5 time points with cumulative data sets, as follows: scenario A, limited prenatal data; scenario B, scenario A plus additional prenatal data; scenario C, scenario B plus data from the first 5 minutes after birth; scenario D, scenario C plus data from the first 24 hours after birth; scenario E, scenario D plus data from the first 1 week after birth. METHODS: Data for all infants with birth weights of 401 to 1000 g who were born between January 1998 and April 2003 in 19 National Institute of Child Health and Human Development Neonatal Research Network centers were used (n = 8608). Twenty-eight variables were selected for analysis (3 for scenario A, 15 for scenario B, 20 for scenario C, 25 for scenario D, and 28 for scenario E) from those collected routinely. Data sets censored for prior death or missing data were created for each scenario and divided randomly into training (70%) and test (30%) data sets. Logistic regression and neural network models for predicting subsequent death were created with training data sets and evaluated with test data sets. The predictive abilities of the models were evaluated with the area under the curve of the receiver operating characteristic curves. RESULTS: The data sets for scenarios A, B, and C were similar, and prediction was best with scenario C (area under the curve: 0.85 for regression; 0.84 for neural networks), compared with scenarios A and B. The logistic regression and neural network models performed similarly well for scenarios A, B, D, and E, but the regression model was superior for scenario C. CONCLUSIONS: Prediction of death is limited even with sophisticated statistical methods such as logistic regression and nonlinear modeling techniques such as neural networks. The difficulty of predicting death should be acknowledged in discussions with families and caregivers about decisions regarding initiation or continuation of care.

Female↗
PubMed2005

[Sorting of packaging cells for retroviral vector carrying green fluorescent gene and viral titer determination].

OBJECTIVE: To develop a method for acquisition of efficient and stable retroviral packaging cells on the basis of fluorescence-activated cell sorting (FACS) technique. METHODS: PA317 cells were transfected by the recombinant retroviral vector pLEGFP via liposome, and the result of transfection was examined using fluorescent microscope. Polyclones and monoclone of the packaging cells were obtained with FACS and identified by PCR and reverse transcriptional PCR (RT-PCR). NIH3T3 cells were used to determine the virus titer in the supernatant. RESULTS: Examination under fluorescence microscope confirmed the success of cell transfection with the retrovirus, and polyclonal and monoclonal cells with efficient and stable expression were obtained after FACS. The inserted EGFP gene fragment could be amplified by PCR from the genomic DNA of the polyclonal and monoclonal cells and by RT-PCR from the retrovirus RNA in the supernatant of monoclonal cell culture and some of the monoclonal cell cultures (6/8). Determination of the virus titer in the cell culture supernatant showed efficient viral production by the cells. CONCLUSION: FACS is an efficient method for obtaining stable retroviral packaging cells.

Gene Expression Regulation, Viral↗
PubMed2005

[Exploring relationship between traditional effects of traditional Chinese medicine and modern pharmacological activities by "co-effect compounds"].

The compound that distributes in the herbs with one common effect was named as "co-effect compound" (CEC). The CECs of three traditional Chinese medicine(TCM) effects, purgative, relieving pain and clearing heat, had been found and studied. A strong corresponding relationship was found between the pharmacological activities of CECs and the TCM effect they belong to. The study shows that it may be a feasible method to connect traditional effect of TCM with modem pharmacological activity.

Anthraquinones↗
PubMed2005

[Marsupialization or decompression of the cystic lesions of the jaws].

Marsupialization or decompression of the cystic lesions of the jaws is the technique that relieves the pressure within the cyst and causes some decrease in size of the lesion, so that subsequent enucleation or curettage could be performed more simply and with less risk to adjacent vital structures. A permanent tooth in the dentigerous cyst in preadolescents often erupts successfully after marsupialization and resolution of the cyst. Large odontogenic keratocyst or unicystic ameloblastoma is marsupialized initially and then enucleated at a later stage, reducing the possibility of pathological fracture of the mandible or the need for jaw resection. However, it should be kept in mind that a few of odontogenic keratocysts or unicystic ameloblastomas still may recur after this two-stage procedure and multi-cystic amelobalstoma has a high recurrence rate and a potential to infiltrate into the surrounding tissues.

Ameloblastoma↗
PubMed2005

[Phase II randomized clinical trail of zoledronic acid in treating metastatic bone pain of malignancy].

BACKGROUND & OBJECTIVE: Bone metastases are the prevailing reason for pain in patients with malignancies, which seriously affect their life quality. Zoledronic acid, the third generation of bisphosphonates, can inhibit the activity of osteoclasts and relieve pain. This study was to evaluate the efficacy and safety of zoledronic acid in treating metastatic bone pain for patients with malignancies. METHODS: A multi-center, randomized, double-blind, and prospective trail was conducted. Patients with metastatic bone pain were randomized to receive zoledromic acid plus monnitol, or pamidronate plus monnitol as positive control. RESULTS: From Oct. 2003 to Oct. 2004, 216 patients with metastatic bone pain were randomized into 2 groups: 109 in zoledromic acid group, and 107 in pamidronate group. There was no significant difference in pain intensity (PI) between zoledromic acid group and pamidronate group before treatment (6.0+/-1.1 vs. 6.0+/-1.3, P=0.938), 7 days after treatment (3.7+/-1.99 vs. 4.1+/-2.0, P=0.119), and 14 days after treatment (3.2+/-2.0 vs. 3.7+/-2.4, P=0.129). The differences in complete response (CR) rate, partial response (PR) rate, and total response rate between the 2 groups were not significant (10.4% vs. 9.5%, 69.8% vs. 69.5%, 88.7% vs. 85.7%, P>0.05). Time to CR was significantly shorter in zoledromic acid group than in pamidronate group [(7.0+/-2.2) days vs. (9.5+/-2.6) days, P=0.033]; the differences in time to PR, duration of CR, and duration of PR between the 2 groups were not significant [(4.9+/-2.6) days vs. (5.0+/-2.5) days, P=0.908; (13.2+/-1.80) days vs. (14.0+/-0.0) days, P=0.155; and (13.4+/-1.9) days vs. (12.8+/-2.8) days, P=0.127]. The main adverse events were fever, nausea, vomiting, and general malaise. The occurrence and severity of adverse events were similar between the 2 groups. CONCLUSION: Zoledromic acid is effective and safe in treating metastatic bone pain of patients with malignancy, which is similar to pamidranate.

Adult↗
PubMed2004

Characterizing the dynamic connectivity between genes by variable parameter regression and Kalman filtering based on temporal gene expression data.

MOTIVATION: One popular method for analyzing functional connectivity between genes is to cluster genes with similar expression profiles. The most popular metrics measuring the similarity (or dissimilarity) among genes include Pearson's correlation, linear regression coefficient and Euclidean distance. As these metrics only give some constant values, they can only depict a stationary connectivity between genes. However, the functional connectivity between genes usually changes with time. Here, we introduce a novel insight for characterizing the relationship between genes and find out a proper mathematical model, variable parameter regression and Kalman filtering to model it. RESULTS: We applied our algorithm to some simulated data and two pairs of real gene expression data. The changes of connectivity in simulated data are closely identical with the truth and the results of two pairs of gene expression data show that our method has successfully demonstrated the dynamic connectivity between genes. CONTACT: jiangtz@nlpr.ia.ac.cn.

Computer Simulation↗
PubMed2004

Identification of differentially expressed genes in individual bovine preimplantation embryos produced by nuclear transfer: improper reprogramming of genes required for development.

Using an interwoven-loop experimental design in conjunction with highly conservative linear mixed model methodology using estimated variance components, 18 genes differentially expressed between nuclear transfer (NT)- and in vitro fertilization (IVF)-produced embryos were identified. The set is comprised of three intermediate-filament protein genes (cytokeratin 8, cytokeratin 19, and vimentin), three metabolic genes (phosphoribosyl pyrophosphate synthetase 1, mitochondrial acetoacetyl-coenzyme A thiolase, and alpha-glucosidase), two lysosomal-related genes (prosaposin and lysosomal-associated membrane protein 2), and a gene associated with stress responses (heat shock protein 27) along with major histocompatibility complex class I, nidogen 2, a putative transport protein, heterogeneous nuclear ribonuclear protein K, mitochondrial 16S rRNA, and ES1 (a zebrafish orthologue of unknown function). The three remaining genes are novel. To our knowledge, this is the first report comparing individual embryos produced by NT and IVF using cDNA microarray technology for any species, and it uses a rigorous experimental design that emphasizes statistical significance to identify differentially expressed genes between NT and IVF embryos in cattle.

Animals↗
PubMed2004

A combinational feature selection and ensemble neural network method for classification of gene expression data.

BACKGROUND: Microarray experiments are becoming a powerful tool for clinical diagnosis, as they have the potential to discover gene expression patterns that are characteristic for a particular disease. To date, this problem has received most attention in the context of cancer research, especially in tumor classification. Various feature selection methods and classifier design strategies also have been generally used and compared. However, most published articles on tumor classification have applied a certain technique to a certain dataset, and recently several researchers compared these techniques based on several public datasets. But, it has been verified that differently selected features reflect different aspects of the dataset and some selected features can obtain better solutions on some certain problems. At the same time, faced with a large amount of microarray data with little knowledge, it is difficult to find the intrinsic characteristics using traditional methods. In this paper, we attempt to introduce a combinational feature selection method in conjunction with ensemble neural networks to generally improve the accuracy and robustness of sample classification. RESULTS: We validate our new method on several recent publicly available datasets both with predictive accuracy of testing samples and through cross validation. Compared with the best performance of other current methods, remarkably improved results can be obtained using our new strategy on a wide range of different datasets. CONCLUSIONS: Thus, we conclude that our methods can obtain more information in microarray data to get more accurate classification and also can help to extract the latent marker genes of the diseases for better diagnosis and treatment.

Acute Disease↗
PubMed2004

Involvement of opioid receptors in electroacupuncture-produced anti-hyperalgesia in rats with peripheral inflammation.

Our previous study showed that electroacupuncture (EA) significantly attenuated inflammatory hyperalgesia. It has also been reported that EA analgesia in uninjured animals is mediated by mu and delta opioid receptors at 2-15 Hz and by kappa opioid receptor at 100 Hz. Because persistent pain changes neural response to external stimulation, we hypothesized that (1) the mechanisms of EA anti-hyperalgesia may be different under conditions of persistent pain and that (2) combining EA with a sub-effective dose of morphine could enhance EA anti-hyperalgesia. Hyperalgesia, decreased paw withdrawal latency (PWL) to a noxious thermal stimulus, was induced by subcutaneously injecting complete Freund's adjuvant (CFA) into the hind paws of rats. Selective antagonists against mu (D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-ThrNH2, CTOP), delta (naltrinodole, NTI) and kappa (nor-binaltorphimine, BNI) opioid receptors were administered intrathecally 10 min before each of two EA treatments at acupoint Huantiao (GB30), one immediately post and the other 2 h post-CFA. Morphine was given (i.p.) 40 min before the second EA treatment. PWL was measured before and 2.5 and 5 h post-CFA. Both 10 and 100 Hz EA-produced anti-hyperalgesia were blocked spinally by mu- and delta- but not kappa-receptor antagonists. EA combined with a sub-threshold dose of morphine (2.5 mg/kg) enhanced anti-hyperalgesia additively (10 Hz EA) or synergistically (100 Hz EA) compared to that produced by each component alone. These results suggest selective involvement of mu and delta, but not kappa, receptors in EA-produced anti-hyperalgesia in rats. A combined EA and opioid drug protocol may provide an improved treatment strategy for inflammatory pain.

Analgesics, Opioid↗