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Lei Wang

Publications and source records attributed to Lei Wang.

At least 73 records · Page 4Linked to original sources
PubMed2006

Regulation of luteinizing hormone receptor mRNA expression by a specific RNA binding protein in the ovary.

The expression of LH receptor mRNA shows significant changes during different physiological states of the ovary. Previous studies from our laboratory have identified a post-transcriptional mechanism by which LH receptor mRNA is regulated following preovulatory LH surge or in response to hCG administration. A specific binding protein, identified as mevalonate kinase, binds to the open reading frame of LH receptor mRNA. The protein binding site is localized to nucleotides 203-220 of the LH receptor mRNA and exhibits a high degree of specificity. The expression levels of the protein show an inverse relationship to the LH receptor mRNA levels. The hCG-induced down-regulation of LH receptor mRNA can be mimicked by increasing the intracellular levels of cyclic AMP by a phosphodiesterase inhibitor. An in vitro mRNA decay assay showed that addition of the binding protein to the decay system caused accelerated LH receptor mRNA decay. Our results therefore show that LH receptor mRNA expression in the ovary is regulated post-transcriptionally by altering the rate of mRNA degradation by a specific mRNA binding protein.

Animals↗
PubMed2006

Conjugated chromophore near the quantum-confined cadmium sulfide cluster: quenched photoluminescence and enhanced two-photon absorption.

Quenching effect of the photoluminescence of 1,2,4,5-tetrakis(4-pyridylvinyl)benzene in the presence of CdS colloids stabilized by inverse micelles was observed. The observed regularities of luminescence quenching by the quenchers of different size were studied. An increase in the two-photon absorption cross section (6.5 times higher) and in the two-photon-induced fluorescence intensity was observed for the composite solution when pumped by 740-nm laser irradiation. The results are in accord with theoretical prediction of enhancement of third-order optical nonlinearity of quantum-confined semiconductor.

Journal Article↗
PubMed2006

Transgenic rice plants ectopically expressing AtBAK1 are semi-dwarfed and hypersensitive to 24-epibrassinolide.

Brassinosteroids (BRs) are endogenous plant hormones essential for plant growth and development. Brassinosteroid insensitive1 (BRI1)-assocaiated receptor kinase (BAK1) is one of the key components in the BR signal transduction pathway due to its direct association with the BR receptor, BRI1. Although BRI1 and its orthologs have been identified from both dicotyledonous and monocotyledonous plants, less is known about BAK1 and its orthologs in higher plants other than Arabidopsis. This article provides the first piece of evidence that AtBAK1 can greatly affect growth and development of rice plants when ectopically expressed, suggesting that rice may share similar BR perception mechanism via BRI1/BAK1 complex. Interestingly, transgenic rice plants displayed semi-dwarfism and shortened primary roots. Physiological analysis and cell morphology assay demonstrated that the observed phenotypes in transgenic plants were presumably caused by hypersensitivity to endogenous levels of BRs, different from BR insensitive and deficient rice mutants. Consistently, several known BR inducible genes were also upregulated in transgenic rice plants, further suggesting that BAK1 was able to affect BR signaling in rice. On the other hand, the transgenic plants generated by overproducing AtBAK1 may potentially have agricultural applications because the dwarfed phenotype is generally resistant to lodging, while the fertility remains unaffected.

Agriculture↗
PubMed2006

Development of a serotype-specific DNA microarray for identification of some Shigella and pathogenic Escherichia coli strains.

Shigella and pathogenic Escherichia coli are major causes of human infectious diseases and are responsible for millions of cases of diarrhea worldwide every year. A convenient and rapid method to identify highly pathogenic serotypes of Shigella and E. coli is needed for large-scale epidemiologic study, timely clinical diagnosis, and reliable quarantine of the pathogens. In this study, a DNA microarray targeting O-serotype-specific genes was developed to detect 15 serotypes of Shigella and E. coli, including Shigella sonnei; Shigella flexneri type 2a; Shigella boydii types 7, 9, 13, 16, and 18; Shigella dysenteriae types 4, 8, and 10; and E. coli O55, O111, O114, O128, and O157. The microarray was tested against 186 representative strains of all Shigella and E. coli O serotypes, 38 clinical isolates, and 9 strains of other bacterial species that are commonly present in stool samples and was shown to be specific and reproducible. The detection sensitivity was 50 ng genomic DNA or 10(4) CFU per ml in mock stool specimens. This is the first report of a microarray for serotyping Shigella and pathogenic E. coli. The method has a number of advantages over traditional bacterial culture and antiserum agglutination methods and is promising for applications in basic microbiological research, clinical diagnosis, food safety, and epidemiological surveillance.

Bacterial Typing Techniques↗
PubMed2006

Soluble expression, purification and functional identification of a disulfide-rich conotoxin derived from Conus litteratus.

Conotoxins are a diverse array of small peptides mostly with multiple disulfide bridges. These peptides become an increasing significant source of neuro-pharmacological probes and drugs as a result of the high selectivity for ion channels and receptors. Usually, the analogue of natural conotoxins is produced by means of chemical synthesis. Here, we present a simple and fast strategy of producing disulfide-rich conotoxins via recombinant expression. By fused with thioredoxin and His tag, a novel O-superfamily conotoxin lt7a was successfully expressed in Escherichia coli and purified, resulting in a high yield of recombinant lt7a about 6 mg/l. The purity of target protein is up to 95% as identified by HPLC results. Whole cell patch-clamp recording revealed that the new conotoxin blocked voltage-sensitive sodium channels in rat dorsal root ganglion neurons, indicating it might be a novel microO-conotoxin.

Animals↗
PubMed2006

Different roles of dopamine receptor subtypes in footshock stress-induced enhancement of morphine conditioned place preference.

The present study investigated the involvement of dopamine mechanism in the effect of intermittent footshock stress on the morphine-induced place preference. A single intermittent footshock session significantly enhanced the place preference induced by 3.0mg/kg morphine. This enhancing effect was inhibited by selective D(1) receptor antagonist SCH23390 and selective D(2) receptor antagonist sulpiride pretreatment 20min before footshock session, suggesting dopamine D(1) and D(2) receptors are required for the development of intermittent footshock stress-induced enhancement of morphine-associated place preference. However, different from D(1) and D(2) receptors this enhancing effect was blocked by stimulation of dopamine D(3) receptor with selective D(3) receptor agonist 7-OH-DPAT pretreatment 20min before footshock session which suggest dopamine D(3) receptor play a negative mediation effect on the intermittent footshock stress-induced this enhancement. These results indicate that dopamine D(1), D(2), and D(3) receptor subtypes play different roles in footshock stress-induced enhancement of morphine conditioned place preference.

Animals↗
PubMed2006

Nonequilibrium properties of the one-dimensional hard-point gas system.

We discuss the stability properties of a one-dimensional hard-point gas. We study the decay of the Loschmidt echo which describes the stability of the motion under system perturbations. We show a universal behavior in the echo decay which is intimately connected to the linear dynamical instability of the motion. In particular, in spite of such a weak instability, the asymptotic decay follows a simple exponential law.

Journal Article↗
PubMed2006

Structure of the O-polysaccharide of Escherichia coli O150 containing 2-acetamido-4-O-[(S)-1-carboxyethyl]-2-deoxy-d-glucose.

An acidic O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Escherichia coli O150 and studied by sugar and methylation analyses, triflic acid solvolysis, Smith degradation, (1)H and (13)C NMR spectroscopy, including 2D ROESY, (1)H,(13)C HSQC, HMQC-TOCSY, and HMBC experiments. The polysaccharide was found to contain a regioisomer of N-acetylisomuramic acid, 2-acetamido-4-O-[(S)-1-carboxyethyl]-2-deoxy-d-glucose [d-GlcNAc4(Slac)]. The structure of its hexasaccharide repeating unit was established.

Carbohydrate Sequence↗
PubMed2006

Characterization and expression of amphioxus ApoD gene encoding an archetype of vertebrate ApoD proteins.

Here we report a homologue of the apolipoprotein D gene (AmphiApoD) in amphioxus, Branchiostoma belcheri tsingtauense, the first such finding in a basal chordate cephalochordate. The main features of the protein predicted from AmphiApoD are characteristic of the apolipoprotein D. Phylogenetic analysis places AmphiApoD at the base of the phylogenetic tree, suggesting that AmphiApoD is the archetype of the vertebrate ApoD genes. Both whole mount in situ hybridization and Northern blotting and RT-PCR as well as in situ hybridization histochemistry reveal that AmphiApoD is expressed in tissues derived from mesoderm and endoderm including notochord and hind-gut, which contrasts with the strong expression patterns of ApoD genes in the ectodermal derivatives in mammals and birds. The expression profiles of the ApoD gene may have been changed to be expressed in the endo-mesodermal derivatives in amphioxus after the vertebrate and cephalochordate lineages diverged; alternatively, the ApoD gene may first have been expressed in the endo-mesoderm during embryogenesis in the last common ancestor of all chordates, and subsequently came to be expressed in the ectodermal derivatives of vertebrates including mammals and birds.

Amino Acid Sequence↗
PubMed2006

Capacity planning for cardiac catheterization: a case study.

BACKGROUND: Excessive waiting for procedures such as cardiac catheterization is an important issue for health care systems. Delays are generally attributed to a mismatch between demand and available capacity. Furthermore, due to the dynamic nature of short-term referral rates, procedure times, and patients' medical urgency, all of which are important contributors to the problem of excessive waiting time, it has been difficult to predict capacity needs accurately. The objective of our paper is to demonstrate how such calculations could be performed. METHODS: After constructing a patient flow model and populating it with appropriate data from 16 consecutive months of operations (n=6215 referrals) of a regional cardiac centre in Ontario, we used computer simulation to simulate the operations of catheterization laboratories in several "what-if" scenarios. We divided the patients into three urgency categories: U1--hospitalized patients, U2--urgent outpatients, U3--elective outpatients. We tested the accuracy of the model by comparing a 1-year sample of computer simulation with actual data which resulted in a highly significant correlation of 0.94. RESULTS: We observed from the referral cohort that waiting times were long, both overall and within each urgency category. We observed from the simulation models that: (1) a one-time infusion of capacity to clear the backlog failed to reduce the waiting times; (2) targeting extra capacity to highest urgency categories reduced waiting times overall and also benefited low urgency patients for whom specific increased capacity was not earmarked; (3) there were no significant effects on waiting times if in some cases patients or referring physicians were able to choose their cath physician; and (4) in situations where the arrival rates increased overall or within specific urgency categories, waiting times increased dramatically and failed to return to baseline for several months to years for the low urgency patients. Efficiency of the labs within the existing capacity could be improved by: (1) reducing changeover time between cases (2) externalizing and standardizing many of the pre- and post-procedural management of the patients, and (3) more carefully balancing the booking to reduce both slack and overtime. INTERPRETATION: Capacity determination is a complex and dynamic process. A combination of available clinical and administrative data, along with a computer simulation model, helps predict capacity needs and is the most appropriate strategy to minimize waiting of patients for procedures. This approach is generalizable and can lead to more effective management of waiting lists for a variety of procedures.

Cardiac Catheterization↗
PubMed2006

Manipulating proteins for neuroscience.

The design and manipulation of proteins has created many tools that have become popular in neurobiological studies, and new developments in protein science will be the fuel for future research. Genetically encoded protein-based biosensors have been developed with a wider range of sensing moieties, enabling detection of changes in localized protein synthesis, voltage, glutamate and/or glucose levels. Existing sensors, such as cameleon, have been modified and improved. Heterologous expression of Channelrhodopsin-2 and other light-gated methods for controlling cellular polarization enable action potentials to be non-invasively evoked, facilitating the study and modulation of behavior in intact animals. Finally, new methods in protein manipulation, including the site-specific incorporation of unnatural amino acids in vivo and the directed evolution of proteins, show promise in elucidating neural function with greater precision and flexibility.

Amino Acids↗
PubMed2006

A biosynthetic pathway for anandamide.

The endocannabinoid arachidonoyl ethanolamine (anandamide) is a lipid transmitter synthesized and released "on demand" by neurons in the brain. Anandamide is also generated by macrophages where its endotoxin (LPS)-induced synthesis has been implicated in the hypotension of septic shock and advanced liver cirrhosis. Anandamide can be generated from its membrane precursor, N-arachidonoyl phosphatidylethanolamine (NAPE) through cleavage by a phospholipase D (NAPE-PLD). Here we document a biosynthetic pathway for anandamide in mouse brain and RAW264.7 macrophages that involves the phospholipase C (PLC)-catalyzed cleavage of NAPE to generate a lipid, phosphoanandamide, which is subsequently dephosphorylated by phosphatases, including PTPN22, previously described as a protein tyrosine phosphatase. Bacterial endotoxin (LPS)-induced synthesis of anandamide in macrophages is mediated exclusively by the PLC/phosphatase pathway, which is up-regulated by LPS, whereas NAPE-PLD is down-regulated by LPS and functions as a salvage pathway of anandamide synthesis when the PLC/phosphatase pathway is compromised. Both PTPN22 and endocannabinoids have been implicated in autoimmune diseases, suggesting that the PLC/phosphatase pathway of anandamide synthesis may be a pharmacotherapeutic target.

Animals↗
PubMed2006

Treatment with bortezomib in a patient with heavily pretreated refractory T-cell lymphoblastic lymphoma.

T-cell lymphoblastic lymphomas are highly aggressive non-Hodgkin's lymphoma (NHL) and account for approximately 3% of all adult NHL histologies, with poor prognosis. We describe a 38-year-old patient with T-cell lymphoblastic lymphoma, who responds to bortezomib and doxorubincin combination, following a failure of conventional chemotherapy. Two months after treatment, the patient showed near complete remission of the lymphadenopathy. These data suggest a possible synergistic effect with bortezomib in combination with doxorubincin and dexamethasone. To our knowledge, this is the first case of T-cell lymphoblastic lymphoma treated with bortezomib.

Adult↗
PubMed2006

Development of gas chromatography-mass spectrometry following headspace single-drop microextraction and simultaneous derivatization for fast determination of short-chain aliphatic amines in water samples.

In this work, for the first time, gas chromatography-mass spectrometry (GC-MS) following headspace single-drop microextraction (HS-SDME) and simultaneous derivatization was developed for fast determination of short-chain aliphatic amines (SCAAs) in water samples. In the proposed method, SCAAs in water samples were headspace extracted and concentrated by suspending a microdrop of solvent, and SCAAs extracted in the microdrop of solvent were simultaneously and rapidly reacted with pentafluorobenzaldehyde (PFBAY). The formed SCAA derivatives were analyzed by GC-MS. The HS-SDME parameters of solvent selection, solvent volume, sample temperature, extraction time and stirring rate were studied, and the method linearity, precision and detection limits, were also studied. The results show that the proposed method provided good linearity (R(2)>0.99, 5.0-500 ng/ml), low detection limit (0.6-1.1 ng/ml), and good precision (RSD value less than 10%). The proposed method was further tested by its application to quantitative analysis of SCAAs in four wastewater samples. The experiment results have demonstrated that GC-MS following HS-SDME and simultaneous derivatization is a simple, rapid and low-cost method for the determination of SCAAs in water samples.

Amines↗
PubMed2006

Preparation and crystal structure of dual-functional precursor complex bis(acetylacetonato)nickel(II) with 4-pyridyltetrathiafulvalene.

A tetrathiafulvalene (TTF) derivative 4-pyridyltetrathiafulvalene (Py-TTF) was synthesized. The 1:2 Ni complex 1 of bis(acetylacetonato)nickel(II) coordinated with Py-TTF was prepared. Complex 1 crystallizes in the monoclinic space group P2(1)/c. Two pyridyl N atoms from two different molecules of Py-TTF are coordinated in the trans configuration to the Ni ion of Ni(acac)2 to form an octahedral Ni complex, which is a precursor for both conducting and magnetic materials.

Journal Article↗
PubMed2006

Treatment of alternated water-electrolyte balance and endocrine status after removal of craniopharyngioma in adults.

BACKGROUND: Water-electrolyte disturbance and endocrine alterations are common complications of adult patients with craniopharygioma in the postoperative period and may affect their recovery and prognosis. Some of these complications even lead to death. Appropriate remedy based upon the status of water-electrolyte balance and the endocrine system is essential to good therapeutic results of adult patients with craniopharyngioma. METHODS: The alterations in water-electrolyte balance (117 patients) and endocrine status (42) of adult patients with craniopharyngioma after surgery were analyzed retrospectively. RESULTS: Most patients with craniopharyngioma experienced postoperative water-electrolyte disturbances and hypotonic dehydration. Moreover, the incidences of hypothyroidism and hypoadrenocorticism were relatively high. CONCLUSION: It is critical to deal with dehydration and endocrine disorders for a sound outcome of craniopharyngioma surgery.

Adolescent↗
PubMed2006

Gene targeting of Cdc42 and Cdc42GAP affirms the critical involvement of Cdc42 in filopodia induction, directed migration, and proliferation in primary mouse embryonic fibroblasts.

Recent studies in Cdc42 knockout mouse embryonic stem (ES) cells and ES-derived fibroblastoid cell lines raise concern on a body of literature derived by dominant mutant expression approach in a variety of cell lines implicating mammalian Cdc42 as a key regulator of filopodia induction, directional migration and cell cycle progression. To resolve the physiological function of mammalian Cdc42, we have characterized the Cdc42(-/-) and Cdc42GAP(-/-) primary mouse embryonic fibroblasts (MEFs) produced by gene targeting as the Cdc42 loss- or gain-of-activity cell model. The Cdc42(-/-) cells were defective in filopodia formation stimulated by bradykinin and in dorsal membrane ruffling stimulated by PDGF, whereas the Cdc42GAP(-/-) cells displayed spontaneous filopodia. The Cdc42 loss- or gain-of-activity cells were defective in adhesion to fibronectin, wound-healing, polarity establishment, and migration toward a serum gradient. These defects were associated with deficiencies of PAK1, GSK3beta, myosin light chain, and FAK phosphorylation. Furthermore, Cdc42(-/-) cells were defective in G1/S-phase transition and survival, correlating with deficient NF-kappaB transcription and defective JNK, p70 S6K, and ERK1/2 activation. These results demonstrate a different requirement of Cdc42 activity in primary MEFs from ES or ES-derived clonal fibroblastoid cells and suggest that Cdc42 plays cell-type-specific signaling roles.

Actins↗