Biomedical subjects

Qiang Lu

Publications and source records attributed to Qiang Lu.

At least 19 recordsLinked to original sources

PubMed2006

Proliferation of neural precursors in the subventricular zone after chemical lesions of the nigrostriatal pathway in rat brain.

The proliferative activity of neural precursors from the subventricular zone (SVZ) was investigated after a unilateral lesion was formed in the nigrostriatal pathway in adult rats. The lesion was formed by unilateral injection of 6-hydroxydopamine (6-OHDA) into the nigrostriatal pathway, and then bromodeoxyuridine (BrdU) was injected (ip) for 4 days or 2 weeks 10 days after the lesion was formed. The rats were killed, and the brain sections were immunohistochemically stained to detect the expression of BrdU, polysialylated neural-cell-adhesion molecule (PSA-NCAM), glial fibrillary acidic protein (GFAP) and tyrosine hydroxylase (TH) in the SVZ and the striatum (STR). The results showed that the BrdU(+) cells increased significantly in the SVZ, ipsilateral to the lesion at 2 weeks after the lesion. The PSA-NCAM(+) and GFAP(+) cells were also increased in the SVZ at this time. Some BrdU-labeled cells were seen in the same side of the STR and were double-labeled with PSA-NCAM. These cells had a tendency to migrate from the SVZ to the STR. The number of positive cells decreased at 4 weeks after the lesion was formed. The number of nigrostriatal projections with TH(+) decreased significantly in the STR on the lesion side, and the level of decrease was related to the quantity of BrdU-labeled cells at 2 weeks. These results indicate that the neural precursors in the SVZ of adult rats may increase after a lesion has been formed in the nigrostriatal pathway, and these cells might migrate into the STR on the same side.

Animals↗

PubMed2006

Single-molecule dynamics reveals cooperative binding-folding in protein recognition.

The study of associations between two biomolecules is the key to understanding molecular function and recognition. Molecular function is often thought to be determined by underlying structures. Here, combining a single-molecule study of protein binding with an energy-landscape-inspired microscopic model, we found strong evidence that biomolecular recognition is determined by flexibilities in addition to structures. Our model is based on coarse-grained molecular dynamics on the residue level with the energy function biased toward the native binding structure (the Go model). With our model, the underlying free-energy landscape of the binding can be explored. There are two distinct conformational states at the free-energy minimum, one with partial folding of CBD itself and significant interface binding of CBD to Cdc42, and the other with native folding of CBD itself and native interface binding of CBD to Cdc42. This shows that the binding process proceeds with a significant interface binding of CBD with Cdc42 first, without a complete folding of CBD itself, and that binding and folding are then coupled to reach the native binding state. The single-molecule experimental finding of dynamic fluctuations among the loosely and closely bound conformational states can be identified with the theoretical, calculated free-energy minimum and explained quantitatively in the model as a result of binding associated with large conformational changes. The theoretical predictions identified certain key residues for binding that were consistent with mutational experiments. The combined study identified fundamental mechanisms and provided insights about designing and further exploring biomolecular recognition with large conformational changes.

Computational Biology↗

PubMed2005

[Cloning and characterization of p43 cDNA from Trichinella spiralis].

OBJECTIVE: To clone and characterize the p43 cDNA from muscle larvae cDNA library of Trichinella spiralis (Ts) Chinese isolate. METHODS: PCR technique was used to amplify the target cDNA from muscle larvae cDNA library. After cloned in pMD18T vector, it was transformed into E. coli NovaBlue. The positive clones were sequenced and the cDNA was cloned into pET28a expression vector. After induced by IPTG, the inclusion body of the recombinant protein was purified and re-natured. The deoxyribonuclease II (DNase II) activity of the recombinant protein was tested by hydrolyzing XDNA. RESULTS: Open reading frame (ORF) of the p43 cDNA was successfully cloned from the muscle larvae cDNA library of the Chinese Ts, there were mutations of two nucleotides in the ORF of the Chinese Ts p43 cDNA comparing with that from U.S.A. isolate at the positions 210 and 604, namely, C and A in the USA isolate but T and G in the Chinese isolate. Considering that three authors had cloned the same p43 cDNA from the USA isolate and six groups (including this team) had also obtained the same sequence from the Chinese isolate, the mutation of the two nucleotides was considered as the single nucleotide polymorphic (SNP) marker of the Chinese Ts isolate. The DNase II activity of the recombinant protein was successfully detected by hydrolyzing lamdaDNA. CONCLUSION: The p43 cDNA was successfully cloned from the muscle larvae cDNA library of the Ts Chinese isolate. Two SNPs were found in the nucleotide sequence. The DNase II activity was proved.

Amino Acid Sequence↗

PubMed2005

Continuous wave-based multiphoton excitation fluorescence for capillary electrophoresis.

It was reported that a novel detection method, continuous wave (CW)-based multiphoton excitation (MPE) fluorescence detection with diode laser (DL), has been firstly proposed for capillary electrophoresis (CE). Special design of end-column detection configuration proved to be superior to on-column type, considering the detection sensitivity. Three different kinds of fluorescent tags that were widely used as molecular label in bio-analysis, such as small-molecule dye, fluorescent protein and nano particle or also referred to as quantum dot (QD), have been evaluated as samples for the constructed detection scheme. Quantitative analyses were also performed using rhodamine species as tests, which revealed dynamic linear range over two orders of magnitude, with detection limit down to zeptomole-level. Simultaneous detection of fluorescent dyestuffs with divergent excitation and emission wavelengths in a broad range showed advantage of this scheme over conventional laser-induced fluorescence (LIF) detection. Further investigations on CW-MPE fluorescence detection with diode laser for capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) separations of fluorescein isothiocyanate (FITC) labeled amino acids indicated good prospect of this detection approach in various micro or nano-column liquid phase separation technologies.

Electrophoresis, Capillary↗

PubMed2005

Multivalent avimer proteins evolved by exon shuffling of a family of human receptor domains.

We have developed a class of binding proteins, called avimers, to overcome the limitations of antibodies and other immunoglobulin-based therapeutic proteins. Avimers are evolved from a large family of human extracellular receptor domains by in vitro exon shuffling and phage display, generating multidomain proteins with binding and inhibitory properties. Linking multiple independent binding domains creates avidity and results in improved affinity and specificity compared with conventional single-epitope binding proteins. Other potential advantages over immunoglobulin domains include simple and efficient production of multitarget-specific molecules in Escherichia coli, improved thermostability and resistance to proteases. Avimers with sub-nM affinities were obtained against five targets. An avimer that inhibits interleukin 6 with 0.8 pM IC50 in cell-based assays is biologically active in two animal models.

Animals↗

PubMed2005

Synthesis and biological activities of aryl-ether-, biaryl-, and fluorene-aspartic acid and diaminopropionic acid analogs as potent inhibitors of the high-affinity glutamate transporter EAAT-2.

Excitatory amino acid transporters (EAATs) play a pivotal role in maintaining glutamate homeostasis in the mammalian central nervous system, with the EAAT-2 subtype thought to be responsible for the bulk of the glutamate uptake in forebrain regions. A complete elucidation of the functional role of EAAT-2 has been hampered by the lack of potent and selective pharmacological tools. In this study, we describe the synthesis and biological activities of novel aryl-ether, biaryl-, and fluorene-aspartic acid and diaminopropionic acid analogs as potent inhibitors of EAAT-2. Compound (16) represents one of the most potent (IC50=85+/-5 nM) and selective inhibitors of EAAT-2 identified to date.

Aspartic Acid↗

PubMed2005

KDE Bioscience: platform for bioinformatics analysis workflows.

Bioinformatics is a dynamic research area in which a large number of algorithms and programs have been developed rapidly and independently without much consideration so far of the need for standardization. The lack of such common standards combined with unfriendly interfaces make it difficult for biologists to learn how to use these tools and to translate the data formats from one to another. Consequently, the construction of an integrative bioinformatics platform to facilitate biologists' research is an urgent and challenging task. KDE Bioscience is a java-based software platform that collects a variety of bioinformatics tools and provides a workflow mechanism to integrate them. Nucleotide and protein sequences from local flat files, web sites, and relational databases can be entered, annotated, and aligned. Several home-made or 3rd-party viewers are built-in to provide visualization of annotations or alignments. KDE Bioscience can also be deployed in client-server mode where simultaneous execution of the same workflow is supported for multiple users. Moreover, workflows can be published as web pages that can be executed from a web browser. The power of KDE Bioscience comes from the integrated algorithms and data sources. With its generic workflow mechanism other novel calculations and simulations can be integrated to augment the current sequence analysis functions. Because of this flexible and extensible architecture, KDE Bioscience makes an ideal integrated informatics environment for future bioinformatics or systems biology research.

Biological Science Disciplines↗

PubMed2005

Structure-based optimization of phenylbutyrate-derived histone deacetylase inhibitors.

Previously, we developed a strategy to develop a novel class of histone deacetylase (HDAC) inhibitors by tethering short-chain fatty acids with Zn(2+)-chelating motifs, which led to N-hydroxy-4-(4-phenylbutyryl-amino)benzamide (HTPB), a hydroxamate-tethered phenylbutyrate derivative with sub-micromolar potency in inhibiting HDAC activity and cancer cell proliferation. In this study, we carried out structure-based optimization of HTPB by using the framework generated by the structure of histone deacetylase-like protein (HDLP)-trichostatin A (TSA) complexes. Docking of HTPB into the HDLP binding domain suggested that the hydrophobic microenvironment encompassed by Phe-198 and Phe-200 could be exploited for structural optimization. This premise was corroborated by the greater potency of (S)-(+)-N-hydroxy-4-(3-methyl-2-phenylbutyrylamino)-benzamide [(S)-11] (IC(50) in HDAC inhibition, 16 nM), of which the isopropyl moiety was favorable in interacting with this hydrophobic motif. (S)-11 at concentrations as low as 0.1 microM was effective in causing histone hyperacetylation and p21(WAF/CIP1) overexpression and suppressing proliferation in cancer cells.

Acetylation↗

PubMed2005

Characterization of novel aryl-ether, biaryl, and fluorene aspartic acid and diaminopropionic acid analogs as potent inhibitors of the high-affinity glutamate transporter EAAT2.

In this study, we describe the pharmacological characterization of novel aryl-ether, biaryl, and fluorene aspartic acid and diaminopropionic acid analogs as potent inhibitors of EAAT2, the predominant glutamate transporter in forebrain regions. The rank order of potency determined for the inhibition of human EAAT2 was N(4)-[4-(2-bromo-4,5-difluorophenoxy)phenyl]-L-asparagine (WAY-213613) (IC(50) = 85 +/- 5 nM) > N(4)-(2'-methyl-1,1'-biphenyl-4-yl)-L-asparagine (WAY-213394) (IC(50) = 145 +/- 22 nM) = N(4)-[7-(trifluoromethyl)-9H-fluoren-2-yl]-L-asparagine (WAY-212922) (IC(50) = 157 +/- 11 nM) = 3-{[(4'-chloro-2-methyl-1,1'-biphenyl-4-yl)carbonyl]amino}-L-alanine (WAY-211686) (IC(50) = 190 +/- 10 nM). WAY-213613 was the most selective of the compounds examined, with IC(50) values for inhibition of EAAT1 and EAAT3 of 5 and 3.8 microM, respectively, corresponding to a 59- and 45-fold selectivity toward EAAT2. An identical rank order of potency [WAY-213613 (35 +/- 7 nM) > WAY-213394 (92 +/- 13 nM) = WAY-212922 (95 +/- 8 nM) = WAY-211686 (101 +/- 20 nM)] was observed for the inhibition of glutamate uptake in rat cortical synaptosomes, consistent with the predominant contribution of EAAT2 to this activity. Kinetic studies with each of the compounds in synaptosomes revealed a competitive mechanism of inhibition. All compounds were determined to be nonsubstrates by evaluating both the stimulation of currents in EAAT2-injected oocytes and the heteroexchange of d-[(3)H]aspartate from cortical synaptosomes. WAY-213613 represents the most potent and selective inhibitor of EAAT2 identified to date. Taken in combination with its selectivity over ionotropic and metabotropic glutamate receptors, this compound represents a potential tool for the further elucidation of EAAT2 function.

Animals↗

PubMed2005

[Detection of anti-Trichinella spiralis antibody by indirect ELISA using recombinant protein as antigen].

OBJECTIVE: To study the specificity, sensitivity of diagnostic antigen for Trichinella spiralis (T.s). METHODS: T668 recombinant protein from highly efficient expression of newborn larvae stage-specific gene of T.s in E. coli as diagnostic antigen. By using negative and positive sera from rabbit, pig, human as the first antibody, and goat-anti-rabbit IgG, goat-anti-pig IgG, goat-anti-human IgG labeled with HRP as the secondary antibody, indirect ELISA method was established for detecting anti-T.s antibody, while excretory-secretory (ES) antigen of T.s muscle larvae was used as control. RESULTS: Sera from rabbit, pig and human were detected by T668 recombinant protein as antigen, which showed a positive rate of 100% with 0.016 microg/well. There was no difference on the results between the T668 recombinant antigen and the ES antigen for diagnosing T.s-infection. CONCLUSION: The T668 recombinant antigen is promising in substituting ES antigen in the detection of anti-T.s antibody.

Animals↗

PubMed2005

Different optic nerve injury sites result in different responses of retinal ganglion cells to brain-derived neurotrophic factor but not neurotrophin-4/5.

In this study, we investigated whether brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT-4/5) can achieve prolonged protection on retinal ganglion cells (RGCs) and whether site of axon injury modulates RGC response to neurotrophins. Two optic nerve (ON) injury paradigms, proximal and distal transections, were used. Autologous sciatic nerves were grafted onto ON stump in some animals to provide a suitable environment for axons to regrow. Multiple intravitreal injections of saline, BDNF, or NT-4/5 were performed. Immunohistochemistry was used to determine the proportion of RGCs that were expressing trkB. Twenty days after proximal injury, both BDNF and NT-4/5 promoted RGC survival; this protection diminished 30 days after injury. One month after distal injury, BDNF, but not NT-4/5, promoted RGC survival (by 2-fold). No difference in the proportion of trkB expressing RGCs among the viable ones was seen between the two injury models or after BDNF treatment. Interestingly, the mean size of RGC somata was larger after proximal injury than distal injury. This study demonstrates that (1) RGCs respond differently to neurotrophins under different injury conditions, (2) BDNF but not NT-4/5 significantly enhances survival of distally but not proximally injured RGCs over a prolonged period.

Animals↗

PubMed2005

[Expression and antigenicity analysis of p46000 antigen from newborn larvae of Trichinella spiralis].

OBJECTIVE: To express and analyze p46000 antigen from newborn larvae of Trichinella spiralis. METHODS: p46000 antigen gene was subcloned to the pET28a expression system by PCR. The recombinant transformant was induced by IPTG and the antigenicity was analyzed with ELISA and Western blotting. RESULTS: The molecular weight of the expressed protein was about Mr 48000. ELISA and Western blotting showed that this recombinant protein could be recognized by T. spiralis infected swine serum and rabbit anti-recombinant protein serum, and the rabbit anti-recombinant protein serum could recognize a Mr 46000 protein from newborn larvae of T. spiralis. CONCLUSION: p46000 recombinant antigen from newborn larvae of T. spiralis was expressed which shows a specific antigenicity.

Animals↗

PubMed2005

PDZ interaction site in ephrinB2 is required for the remodeling of lymphatic vasculature.

The transmembrane ligand ephrinB2 and its cognate Eph receptor tyrosine kinases are important regulators of embryonic blood vascular morphogenesis. However, the molecular mechanisms required for ephrinB2 transduced cellular signaling in vivo have not been characterized. To address this question, we generated two sets of knock-in mice: ephrinB2DeltaV mice expressed ephrinB2 lacking the C-terminal PDZ interaction site, and ephrinB2(5F) mice expressed ephrinB2 in which the five conserved tyrosine residues were replaced by phenylalanine to disrupt phosphotyrosine-dependent signaling events. Our analysis revealed that the homozygous mutant mice survived the requirement of ephrinB2 in embryonic blood vascular remodeling. However, ephrinB2DeltaV/DeltaV mice exhibited major lymphatic defects, including a failure to remodel their primary lymphatic capillary plexus into a hierarchical vessel network, hyperplasia, and lack of luminal valve formation. Unexpectedly, ephrinB2(5F/5F) mice displayed only a mild lymphatic phenotype. Our studies define ephrinB2 as an essential regulator of lymphatic development and indicate that interactions with PDZ domain effectors are required to mediate its functions.

Amino Acid Sequence↗

PubMed2005

CNTF and BDNF have similar effects on retinal ganglion cell survival but differential effects on nitric oxide synthase expression soon after optic nerve injury.

PURPOSE: To investigate the effect of ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) on retinal ganglion cell (RGC) survival and nitric oxide synthase (NOS) expression in the retina during the early phase of optic nerve (ON) injury, and to examine whether intraperitoneal application of the NOS scavenger nitro-l-arginine (l-NA) could protect the injured RGCs. METHODS: RGCs were retrogradely labeled with granular blue 3 days before the ON was intraorbitally transected. RGC survival was examined 1 week after ON transection and intraocular injection of CNTF and/or BDNF, or 1 to 2 weeks after daily intraperitoneal injection of the NOS inhibitor l-NA. NOS expression was examined by NADPH-diaphorase histochemistry and neuronal NOS (nNOS) immunohistochemistry, and nNOS-positive cells were identified by various staining approaches. RESULTS: Both CNTF and BDNF significantly increased RGC survival 1 week after ON injury. In the ganglion cell layer (GCL), CNTF did not increase the number of NADPH-diaphorase positive ((+)) cells but appeared to reduce the intensity of NADPH-diaphorase staining, whereas BDNF increased the number of NADPH-diaphorase(+) cells and also appeared to enhance the intensity of NADPH-diaphorase staining. In the GCL, amacrine cells but not RGCs were nNOS(+). Some macrophages were also nNOS(+). In contrast, no amacrine cells were nNOS(+) in the inner nuclear layer. Daily intraperitoneal injection of l-NA at appropriate concentrations promoted RGC survival for 1 or 2 weeks after ON injury. CONCLUSIONS: Both CNTF and BDNF protected RGCs after ON injury. CNTF and BDNF acted differently on NOS expression in the GCL. Intraperitoneal injections of l-NA at appropriate dosages enhance RGC survival.

Animals↗

PubMed2004

Laser speckle imaging of blood flow in microcirculation.

Monitoring the spatio-temporal characteristics of microcirculation is crucial for studying the functional activities of biotissue and the mechanism of disease. However, conventional methods used to measure blood flow suffer from limited spatial resolution or the injection of exogenous substances or the need of scanning to obtain the dynamic of regional blood flow. Laser speckle imaging (LSI) technique makes up these disadvantages by obtaining the regional blood flow distribution with high spatio-temporal resolution without the need to scan. In this paper, LSI was introduced to investigate the dynamic responses of the rat mesenteric microcirculation to an incremental dose of phentolamine. The results showed that when the dose of phentolamine was less than 4 microg ml(-1), local application of phentolamine on the mesentery would increase the blood perfusion as the concentration increased. When the dose increased further, the improvement decreased. At a dose of 200 microg ml(-1), a microcirculation impediment was caused. At the same time, different responses between veinules and arterioles were manifested. These suggested that LSI is promising to be a useful contribution to drug development and testing.

Animals↗

PubMed2004

Monte Carlo modeling of optical coherence tomography imaging through turbid media.

We combine a Monte Carlo technique with Mie theory to develop a method for simulating optical coherence tomography (OCT) imaging through homogeneous turbid media. In our model the propagating light is represented by a plane wavelet; its line propagation direction and path length in the turbid medium are determined by the Monte Carlo technique, and the process of scattering by small particles is computed according to Mie theory. Incorporated into the model is the numerical phase function obtained with Mie theory. The effect of phase function on simulation is also illustrated. Based on this improved Monte Carlo technique, OCT imaging is directly simulated and phase information is recorded. Speckles, resolution, and coherence gating are discussed. The simulation results show that axial and transversal resolutions decrease as probing depth increases. Adapting a light source with a low coherence improves the resolution. The selection of an appropriate coherence length involves a trade-off between intensity and resolution.

Computer Simulation↗

PubMed2004

Zn2+-chelating motif-tethered short-chain fatty acids as a novel class of histone deacetylase inhibitors.

Among various classes of histone deacetylase (HDAC) inhibitors, short-chain fatty acids exhibit the least potency, with IC(50) in the millimolar range. We rationalized that this weak potency was, in part, attributable to their inability to access the zinc cation in the HDAC active-site pocket, which is pivotal to the deacetylation catalysis. We thus explored the structural optimization of valproate, butyrate, phenylacetate, and phenylbutyrate by coupling them with Zn(2+)-chelating motifs (hydroxamic acid and o-phenylenediamine) through aromatic omega-amino acid linkers. This strategy has led to a novel class of Zn(2+)-chelating, motif-tethered, short-chain fatty acids that exhibited varying degrees of HDAC inhibitory potency. One hydroxamate-tethered phenylbutyrate compound, N-hydroxy-4-(4-phenylbutyrylamino)benzamide (HTPB), displayed nanomolar potency in inhibiting HDAC activity. Exposure of several cancer cell lines to HTPB at the submicromolar level showed reduced cell proliferation accompanied by histone hyperacetylation and elevated p21(WAF/CIP1) expression, which are hallmark features associated with intracellular HDAC inhibition.

Acetylation↗

PubMed2004

Analysis of PDZ-RGS3 function in ephrin-B reverse signaling.

Transmembrane B ephrins and their Eph receptors signal bidirectionally. However, the molecular and cellular mechanisms of the "reverse signaling" by B ephrins are not fully understood. The identification of several B ephrin cytoplasmic domain-interacting proteins has begun to shed light on the signal transduction mechanisms and the cellular effects of B ephrin reverse signaling. This article describes the use of a Transwell migration assay system to characterize the function of a PDZ domain and a regulator of G-protein signaling (RGS) domain-containing protein, PDZ-RGS3, in mediating B ephrin reverse signaling in cultured neurons. The Transwell system discussed here can provide an effective cell-based assay for elucidating RGS protein-mediated signaling interactions in neurons.

Animals↗