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Biomedical subjects

Wei Qiu

Publications and source records attributed to Wei Qiu.

At least 19 recordsLinked to original sources

A lipidomic study on the lens epithelial cells of patients with age related cataracts.

Age related cataracts (ARC) represent the main reason for blindness globally. The lens epithelial cells (LECs) participate not only in the metabolism of many substances in the lens but also in maintaining lens transparency. This study used lipidomics to investigate the metabolic differences in LECs of ARC patients with different severity, aiming at identifying potential metabolic biomarkers of ARC. Patients diagnosed with ARC and underwent cataract surgery at Shanghai Tongren Hospital were selected to participate in this study, which were classified as mild ARC group and severe ARC group. During their cataract surgery, anterior lens capsules(LCs) containing LECs were obtained. The lipidomics of LECs were analyzed using the liquid chromatography‑mass spectrometry (LC-MS). Potential pathways of lipids were searched for using databases such as the Kyoto Encyclopedia of Genes and Genomes (KEGG) and MetaboAnalyst platform. In LEC lipids, 26 lipids have been identified as potential biomarkers between mild ARC and severe ARC, with AUC values of 0.67-0.94. The pathway analysis results revealed that the Glycerophospholipid (GPL) metabolism was significantly influenced, indicating that these metabolic markers contribute significantly to regulating this pathway. The LEC metabolic spectrum demonstrates a proficient ability to differentiate between patients with varying levels of cataracts. Herein, we have successfully identified potential metabolic biomarkers and pathways that have proven to be valuable in enhancing our understanding of ARC pathogenesis. The finding has translational value for developing new cataract treatment methods in the future.

Humans↗

Structure-based inhibitor design for an enzyme that binds different steroids: a potent inhibitor for human type 5 17beta-hydroxysteroid dehydrogenase.

Human type 5 17beta-hydroxysteroid dehydrogenase plays a crucial role in local androgen formation in prostate tissue. Several chemicals were synthesized and tested for their ability to inhibit this enzyme, and a series of estradiol derivatives bearing a lactone on the D-ring were found to inhibit its activity efficiently. The crystal structure of the type 5 enzyme in complex with NADP and such a novel inhibitor, EM1404, was determined to a resolution of 1.30 A. Significantly more hydrogen bonding and hydrophobic interactions were defined between EM1404 and the enzyme than in the substrate ternary complex. The lactone ring of EM1404 accounts for important interactions with the enzyme, whereas the amide group at the opposite end of the inhibitor contributes to the stability of three protein loops involved in the construction of the substrate binding site. EM1404 has a strong competitive inhibition, with a Ki of 6.9+/-1.4 nM, demonstrating 40 times higher affinity than that of the best inhibitor previously reported. This is observed despite the fact that the inhibitor occupies only part of the binding cavity. Attempts to soak the inhibitor into crystals of the binary complex with NADP were unsuccessful, yielding a structure with a polyethylene glycol fragment occupying the substrate binding site. The relative crystal packing is discussed. Combined studies of small molecule inhibitor synthesis, x-ray crystallography, enzyme inhibition, and molecular modeling make it possible to analyze the plasticity of the substrate binding site of the enzyme, which is essential for developing more potent and specific inhibitors for hormone-dependent cancer therapy.

17-Hydroxysteroid Dehydrogenases↗

p53 independent induction of PUMA mediates intestinal apoptosis in response to ischaemia-reperfusion.

BACKGROUND: The small intestine is highly sensitive to ischaemia-reperfusion (I/R) induced injury which is associated with high morbidity and mortality. Apoptosis, or programmed cell death, is a major mode of cell death occurring during I/R induced injury. However, the mechanisms by which I/R cause apoptosis in the small intestine are poorly understood. p53 upregulated modulator of apoptosis (PUMA) is a p53 downstream target and a member of the BH3-only group of Bcl-2 family proteins. It has been shown that PUMA plays an essential role in apoptosis induced by a variety of stimuli in different tissues through a mitochondrial pathway. AIMS: The role of PUMA in I/R induced injury and apoptosis in the small intestine was investigated. The mechanisms by which PUMA is regulated in I/R induced intestinal apoptosis were also studied. METHODS: Ischaemia was induced by superior mesenteric artery occlusion in the mouse small intestine. Induction of PUMA in response to ischaemia alone, or ischaemia followed by reperfusion (I/R), was examined. I/R induced intestinal apoptosis and injury were compared between PUMA knockout and wild-type mice. The mechanisms of I/R induced and PUMA mediated apoptosis were investigated through analysis of caspase activation, cytosolic release of mitochondrial cytochrome c and alterations of the proapoptotic Bcl-2 family proteins Bax and Bak. To determine whether PUMA is induced by reactive oxygen species and/or reactive nitrogen species generated by I/R, superoxide dismutase (SOD) and N-nitro-l-arginine methyl ester (L-NAME) were used to treat animals before I/R. To determine whether p53 is involved in regulating PUMA during I/R induced apoptosis, PUMA induction and apoptosis in response to I/R were examined in p53 knockout mice. RESULTS: PUMA was markedly induced following I/R in the mucosa of the mouse small intestine. I/R induced intestinal apoptosis was significantly attenuated in PUMA knockout mice compared with that in wild-type mice. I/R induced caspase 3 activation, cytochrome c release, Bax mitochondrial translocation and Bak multimerisation were also inhibited in PUMA knockout mice. SOD or L-NAME significantly blunted I/R induced PUMA expression and apoptosis. Furthermore, I/R induced PUMA expression and apoptosis in the small intestine were not affected in the p53 knockout mice. CONCLUSIONS: Our data demonstrated that PUMA is activated by oxidative stress in response to I/R to promote p53 independent apoptosis in the small intestine through the mitochondrial pathway. Inhibition of PUMA is potentially useful for protecting against I/R induced intestinal injury and apoptosis.

Animals↗

Genome-scale protein expression and structural biology of Plasmodium falciparum and related Apicomplexan organisms.

Parasites from the protozoan phylum Apicomplexa are responsible for diseases, such as malaria, toxoplasmosis and cryptosporidiosis, all of which have significantly higher rates of mortality and morbidity in economically underdeveloped regions of the world. Advances in vaccine development and drug discovery are urgently needed to control these diseases and can be facilitated by production of purified recombinant proteins from Apicomplexan genomes and determination of their 3D structures. To date, both heterologous expression and crystallization of Apicomplexan proteins have seen only limited success. In an effort to explore the effectiveness of producing and crystallizing proteins on a genome-scale using a standardized methodology, over 400 distinct Plasmodium falciparum target genes were chosen representing different cellular classes, along with select orthologues from four other Plasmodium species as well as Cryptosporidium parvum and Toxoplasma gondii. From a total of 1008 genes from the seven genomes, 304 (30.2%) produced purified soluble proteins and 97 (9.6%) crystallized, culminating in 36 crystal structures. These results demonstrate that, contrary to previous findings, a standardized platform using Escherichia coli can be effective for genome-scale production and crystallography of Apicomplexan proteins. Predictably, orthologous proteins from different Apicomplexan genomes behaved differently in expression, purification and crystallization, although the overall success rates of Plasmodium orthologues do not differ significantly. Their differences were effectively exploited to elevate the overall productivity to levels comparable to the most successful ongoing structural genomics projects: 229 of the 468 target genes produced purified soluble protein from one or more organisms, with 80 and 32 of the purified targets, respectively, leading to crystals and ultimately structures from one or more orthologues.

Animals↗

DeltaNp63 plays an anti-apoptotic role in ventral bladder development.

The bladder, the largest smooth-muscle organ in the human body, is responsible for urine storage and micturition. P63, a homolog of the p53 tumor-suppressor gene, is essential for the development of all stratified epithelia, including the bladder urothelium. The N-terminal truncated isoform of p63, DeltaNp63, is known to have anti-apoptotic characteristics. We have established that DeltaNp63 is not only the predominant isoform expressed throughout the bladder, but is also preferentially expressed in the ventral bladder urothelium during early development. We observed a host of ventral defects in p63-/- embryos, including the absence of the abdominal and ventral bladder walls. This number of ventral defects is identical to bladder exstrophy, a congenital anomaly exhibited in human neonates. In the absence of p63, the ventral urothelium was neither committed nor differentiated, whereas the dorsal urothelium was both committed and differentiated. Furthermore, in p63-/- bladders, apoptosis in the ventral urothelium was significantly increased. This was accompanied by the upregulation of mitochondrial apoptotic mediators Bax and Apaf1, and concurrent upregulation of p53. Overexpression of DeltaNp63gamma and DeltaNp63beta in p63-/- bladder primary cell cultures resulted in a rescue, evidenced by significantly reduced expressions of Bax and Apaf1. We conclude that DeltaNp63 plays a crucial anti-apoptotic role in normal bladder development.

Animals↗

MEK-ERK inhibition corrects the defect in VLDL assembly in HepG2 cells: potential role of ERK in VLDL-ApoB100 particle assembly.

OBJECTIVE: Hepatic VLDL assembly is defective in HepG2 cells, resulting in the secretion of immature triglyceride-poor LDL-sized apoB particles. We investigated the mechanisms underlying defective VLDL assembly in HepG2 and have obtained evidence implicating the MEK-ERK pathway. METHODS AND RESULTS: HepG2 cells exhibited considerably higher levels of the ERK1/2 mass and activity compared with primary hepatocytes. Inhibition of ERK1/2 using the MEK1/MEK2 inhibitor, U0126 (but not the inactive analogue) led to a significant increase in apoB secretion. In the presence of oleic acid, ERK1/2 inhibition caused a major shift in the lipoprotein distribution with a majority of particles secreted as VLDL, an effect independent of insulin. In contrast, overexpression of constitutively active MEK1 decreased apoB and large VLDL secretion. MEK1/2 inhibition significantly increased both cellular and microsomal TG mass, and mRNA levels for DGAT-1 and DGAT-2. In contrast to ERK, modulation of the PI3-K pathway or inhibition of the p38 MAP kinase, had no effect on lipoprotein density profile. Modulation of the MEK-ERK pathway in primary hamster hepatocytes led to changes in apoB secretion and altered the density profile of apoB-containing lipoproteins. CONCLUSIONS: Inhibition of the overactive ras-MEK-ERK pathway in HepG2 cells can correct the defect in VLDL assembly leading to the secretion of large, VLDL-sized particles, similar to primary hepatocytes, implicating the MEK-ERK cascade in VLDL assembly in the HepG2 model. Modulation of this pathway in primary hepatocytes also regulates apoB secretion and appears to alter the formation of VLDL-1 sized particles.

Animals↗

Regional identification, partition, and integral phase unwrapping method for processing moiré interferometry images.

We present a new method of regional identification, partition, and integral (RIPI) phase unwrapping for processing images, especially those with low quality, obtained from moiré interferometry experiments. By introducing the principle of preorder traversal of a general tree in data structures and then by applying the idea of a regional integral, the proposed method makes regional partition and phase evaluation much easier and more accurate, and it also overcomes the common faults that can occur when conventional approaches, such as line defects, are used. Examples are given to demonstrate the advantage and applicability of the proposed RIPI method when processing experimental images. It is shown that the proposed method works well for global phase distribution, and, at the same time, local mutational information is preserved and limited to its vicinity without affecting other parts.

Journal Article↗

Immortalization of normal human cytotrophoblast cells by reconstitution of telomeric reverse transcriptase activity.

Placental trophoblast cells are unique endocrine cells that play vital roles during the processes of embryonic implantation and placentation. However, research into the function of human trophoblast has been largely restrained mainly due to a lack of adequate cell models. A normal placenta-origin cytotrophoblast cell line (NPC) was previously established by our group, but these cells showed replicating senescence after 50 population doublings (PDs). In this study, the human telomerase catalytic subunit gene (htert) was transferred into B6 strain of NPC cells, and strains with reconstituted telomerase activity (B6Tert) were established. It was shown that B6Tert-1 cells produce various biomarkers of normal extravillous cytotrophoblasts during the early weeks of gestation. Meanwhile, the cell invasiveness was inhibited by transforming growth factor beta (TGFbeta). However, their ability to form syncytium was relatively low when stimulated with fetal calf serum (FCS). The cells maintained normal cell growth properties and failed to elicit tumours in nude mice. They proliferated continuously with no signs of senescence until the final count at 210 PDs. The growth rate of B6Tert-1 cells was increased when compared with the parental cells, which results, at least partly, from facilitating release of the G1/S checkpoint during the cell-cycle regulation. This is the first report of immortalizing human normal cytotrophoblast (CTB) cells by activation of telomerase activity. The cells will provide an ideal in vitro model for the study of human extravillous trophoblast (EVT) functions and consequently the mechanisms of embryonic implantation and placentation.

Animals↗

Mechanisms of glucosamine-induced suppression of the hepatic assembly and secretion of apolipoprotein B-100-containing lipoproteins.

Glucosamine-induced endoplasmic reticulum (ER) stress was recently shown to specifically reduce apolipoprotein B-100 (apoB-100) secretion by enhancing the proteasomal degradation of apoB-100. Here, we examined the mechanisms linking glucosamine-induced ER stress and apoB-lipoprotein biogenesis. Trypsin sensitivity studies suggested glucosamine-induced changes in apoB-100 conformation. Endoglycosidase H studies of newly synthesized apoB-100 revealed glucosamine induced N-linked glycosylation defects resulting in reduced apoB-100 secretion. We also examined glucosamine-induced changes in VLDL assembly and secretion. A dose-dependent (1-10 mM glucosamine) reduction was observed in VLDL-apoB-100 secretion in primary hepatocytes (24.2-67.3%) and rat McA-RH7777 cells (23.2-89.5%). Glucosamine also inhibited the assembly of larger VLDL-, LDL-, and intermediate density lipoprotein-apoB-100 but did not affect smaller HDL-sized apoB-100 particles. Glucosamine treatment during the chase period (posttranslational) led to a 24% reduction in apoB-100 secretion (P < 0.01; n = 4) and promoted post-ER apoB degradation. However, the contribution of post-ER apoB-100 degradation appeared to be quantitatively minor. Interestingly, the glucosamine-induced posttranslational reduction in apoB-100 secretion could be partially prevented by treatment with desferrioxamine or vitamin E. Together, these data suggest that cotranslational glucosamine treatment may cause defects in apoB-100 N-linked glycosylation and folding, resulting in enhanced proteasomal degradation. Posttranslationally, glucosamine may interfere with the assembly process of apoB lipoproteins, leading to post-ER degradation via nonproteasomal pathways.

Animals↗

Real-time data-reusing adaptive learning of a radial basis function network for tracking evoked potentials.

Tracking variations in both the latency and amplitude of evoked potential (EP) is important in quantifying properties of the nervous system. Adaptive filtering is a powerful tool for tracking such variations. In this paper, a data-reusing non-linear adaptive filtering method, based on a radial basis function network (RBFN), is implemented to estimate EP. The RBFN consists of an input layer of source nodes, a single hidden layer of non-linear processing units and an output layer of linear weights. It has built-in nonlinear activation functions that allow learning of function mappings. Moreover, it produces satisfactory estimates of signals against a background noise without a priori knowledge of the signal, provided that the signal and noise are independent. In clinical situations where EP responses change rapidly, the convergence rate of the algorithm becomes a critical factor. A carefully designed data-reusing RBFN can accelerate the convergence rate markedly and, thus, enhance its performance. Both theoretical analysis and simulation results support the improved performance of our new algorithm.

Adolescent↗

The kurtosis metric as an adjunct to energy in the prediction of trauma from continuous, nonGaussian noise exposures.

Data from an earlier study [Hamernik et al. (2003). J. Acoust. Soc. Am. 114, 386-395] were consistent in showing that, for equivalent energy [Leq= 100 dB(A)] and spectra, exposure to a continuous, nonGaussian (nonG) noise could produce substantially greater hearing and sensory cell loss in the chinchilla model than a Gaussian (G) noise exposure and that the statistical metric, kurtosis, computed on the amplitude distribution of the noise could order the extent of the trauma. This paper extends these results to Leq= 90 and 110 dB(A), and to nonG noises that are generated using broadband noise bursts, and band limited impacts within a continuous G background noise. Data from nine new experimental groups with 11 or 12 chinchillas/group is presented. Evoked response audiometry established hearing thresholds and surface preparation histology quantified sensory cell loss. At the lowest level [Leq=90 dB(A)] there were no differences in the trauma produced by G and nonG exposures. For Leq >90 dB(A) nonG exposures produced increased trauma relative to equivalent G exposures. Removing energy from the impacts by limiting their bandwidth reduced trauma. The use of noise bursts to produce the nonG noise instead of impacts also reduced the amount of trauma.

Animals↗

Dual effect of transforming growth factor beta1 on cell adhesion and invasion in human placenta trophoblast cells.

Transforming growth factor beta (TGFbeta) has been shown to be a multifunctional cytokine required for embryonic development and regulation of trophoblast cell behaviors. In the present study, a non-transformed cell-line representative of normal human trophoblast (NPC) was used to examine the effect of TGFbeta1 on trophoblast cell adhesion and invasion. In vitro assay showed that TGFbeta1 could significantly promote intercellular adhesion, while inhibiting cell invasion across the collagen I-coated filter. Reverse transcription (RT)-PCR and gelatin zymography demonstrated that TGFbeta1 evidently repressed the mRNA expression and proenzyme production of matrix metalloproteinase (MMP)-9, but exerted no effect on mRNA expression and secretion of MMP-2. On the other hand, both the mRNA and protein expression of epithelial-cadherin and beta-catenin were obviously upregulated by TGFbeta1 in dose-dependent fashion, as revealed by RT-PCR and western-blot analysis. What is more, one of the critical TGFbeta signaling molecules - Smad2 was notably phosphorylated in TGFbeta1-treated NPC cells. The data indicates that cell invasion and adhesion are coordinated processes in human trophoblasts and that there exists paracrine regulation on adhesion molecules and invasion-associated enzymes in human placenta.

Analysis of Variance↗

[Applying analytical hierarchy process to assess eco-environment quality of Heilongjiang province].

The analytical hierarchy process (AHP) was adopted to study the index system of eco-province and the index system was set up for eco-province construction. The comparison matrix was constructed on the basis of experts' investigation questionnaires. MATLAB 6.5 was used to confirm the weights of the indices. The general environment quality index model was used to grade the environment quality and assessed the progress of constructing eco-province in Heilongjiang province. The results indicate that it is feasible to apply the AHP to assess quantitatively the ecological environmental quality province-wide. The ecological environment quality of Heilongjiang province has been improved obviously from the beginning of eco-province construction.

China↗

Estradiol-adenosine hybrid compounds designed to inhibit type 1 17beta-hydroxysteroid dehydrogenase.

The steroidogenic enzyme type 1 17beta-hydroxysteroid dehydrogenase (17beta-HSD) is involved in the synthesis of estradiol (E(2)), a hormone well-known to stimulate the growth of estrogen-sensitive tumors. To obtain compounds able to control E(2) formation, two moieties were linked with a methylene side chain: an adenosine moiety for interacting with the cofactor-binding site and an E(2) moiety for interacting with the substrate-binding site. When tested as inhibitors of type 1 17beta-HSD, the hybrid compounds inhibited the reductive activity (E(1) into E(2)) with IC(50) values ranging from 52 to 1,000 nM. The optimal side-chain length was determined to be eight methylene groups for a 16 beta-orientation. The presence of two components (E(2) and adenosine) is essential for good inhibition, since 16 beta-nonyl-E(2) and 5-nonanoyl-O-adenosine, two compounds having only one of the components, did not inhibit the enzyme. Moreover, the 3D-structure analysis of EM-1,745 complexed with type 1 17beta-HSD showed key interactions with both substrate- and cofactor-binding sites.

17-Hydroxysteroid Dehydrogenases↗

MDM2 promotes proteasome-dependent ubiquitin-independent degradation of retinoblastoma protein.

Inactivation of retinoblastoma protein (Rb) plays a critical role in the development of human malignancies. It has been shown that Rb is degraded through a proteasome-dependent pathway, yet the mechanism is largely unclear. MDM2 is frequently found amplified and overexpressed in a variety of human tumors. In this study, we find that MDM2 promotes Rb degradation in a proteasome-dependent and ubiquitin-independent manner. We show that Rb, MDM2, and the C8 subunit of the 20S proteasome interact in vitro and in vivo and that MDM2 promotes Rb-C8 interaction. Expression of wild-type MDM2, but not the mutant MDM2 defective either in Rb interaction or in RING finger domain, promotes cell cycle S phase entry independent of p53. Furthermore, MDM2 ablation results in Rb accumulation and inhibition of DNA synthesis. Taken together, these findings demonstrate that MDM2 is a critical negative regulator for Rb and suggest that MDM2 overexpression contributes to cancer development by destabilizing Rb.

Cell Line, Tumor↗

Oleate-mediated stimulation of microsomal triglyceride transfer protein (MTP) gene promoter: implications for hepatic MTP overexpression in insulin resistance.

Hepatic lipoprotein overproduction in a fructose-fed hamster model of insulin resistance was previously shown to be associated with a significant elevation of intracellular mass of microsomal triglyceride transfer protein (MTP) and elevated plasma levels of free fatty acids (FFA). Here, we further establish that fructose feeding and development of an insulin resistant state result in higher levels of MTP mRNA, protein mass, and lipid transfer activity. MTP protein mass was increased in fructose-fed hamster hepatocytes to 161 +/- 35.8% of control (p < 0.05), while MTP mRNA levels and MTP lipid transfer activity were increased to 147.5 +/- 30.8% (p < 0.05) and 177.5 +/- 14.5% (p < 0.05) of control levels, respectively. To identify underlying mechanisms, we also investigated the potential link between enhanced FFA flux and hepatic MTP gene expression. Direct modulation of MTP gene transcription by fatty acids was investigated by transfecting HepG2 cells with a reporter (luciferase) construct containing various base pair regions of the human MTP promoter including pMTP124 (with the sterol response element (SRE)), pMTP116, pMTP109 and pMTP100 (no SRE), and pMTP124SREKO (SRE sequences mutated). Treatment of HepG2 cells with oleic acid (360 muM) significantly increased luciferase activities in cells transfected with pMTP124 (136.6 +/- 11.0%, p < 0.05) and pMTP124SREKO (153.9 +/- 11.1%, p < 0.01) compared with control. Luciferase activity was also increased in a time and dose-dependent manner in the presence of oleic acid when transfected with pMTP124SREKO but not pMTP109 and pMTP100. Furthermore, long-term oleic acid treatment of HepG2 cells (10 days) induced higher levels of MTP mRNA (p < 0.05) confirming transcriptional stimulation of the MTP gene by oleic acid. In contrast, palmitate, arachidonic acid or linoleic acid did not significantly stimulate pMTP124 or pMTP124SREKO luciferase activity (p > 0.05). These data demonstrate that (1) MTP gene transcription may be directly up-regulated by oleic acid; (2) up-regulation of MTP gene transcription by oleic acid is SRE sequence independent; and (3) the sequence -116 to -109 in the MTP promoter region is essential for oleic acid-mediated stimulation. Stimulation of MTP gene expression may be a novel mechanism by which certain FFAs can induce hepatic lipoprotein secretion in insulin resistant states.

Animals↗

Multi-adaptive filtering technique for surface somatosensory evoked potentials processing.

Somatosensory evoked potential (SEP) testing has been widely applied to diagnosis of various neurological disorders. However, SEP recorded using surface electrodes is buried in noises, which makes the signal-to-noise ratio (SNR) very poor. Conventional averaging method usually requires up to thousands of raw SEP input trials to increase the SNR so that an identifiable waveform can be produced for latency and amplitude measurement. In this study, a multi-adaptive filtering (MAF) technique, emerging from the combination of well-developed adaptive noise canceller and adaptive signal enhancer, is introduced for fast and accurate surface SEP extraction. The MAF technique first processes the raw surface recorded SEP by the Canceller with a reference noise channel of background noise for adaptive subtraction before entering the Enhancer. The MAF was verified by filtering simulated SEP signals in which electroencephalography and Gaussian noise of different SNRs were added. It was found that the MAF could effectively suppress the noise and enhance the SEP components such that the SNR of the SEP is improved. Results showed that MAF with 50 input trials could provide similar performance in SEP detection to those extracted by the conventional averaging method with 1000 trials even at an SNR of -20 dB.

Algorithms↗

Design and synthesis of protein superfamily-targeted chemical libraries for lead identification and optimization.

This review chronicles original literature dating back to 1992 outlining the applications of parallel synthesis and combinatorial chemistry to the synthesis of compound libraries focused towards specific superfamilies of molecular targets. Target families that have received significant literature coverage include kinases, proteases, nuclear hormone receptors and cell surface receptors, notably GPCRs.

Drug Design↗