Biomedical subjects

Yue Wang

Publications and source records attributed to Yue Wang.

At least 55 records · Page 3Linked to original sources

PubMed2006

Theoretical study on photophysical and charge transport properties of 1,6-bis(2-hydroxyphenol)pyridylboron bis(4-n-butylphenyl)phenyleneamine compound.

The absorption and emission spectra of 1,6-bis(2-hydroxyphenol)pyridylboron bis(4-n-butylphenyl)phenyleneamine were systematically calculated by time-dependent density functional theory (TD-DFT) level. These results are in good agreement with experiment ones. The charge transport properties were investigated within the framework of the charge hopping model. The results show that 1,6-bis(2-hydroxyphenyl)pyridineboron ((dppy)BF) functions as a electron transport group and triphenylamine as a hole transport group; the charge transport ability for the two types of carriers is not only high but also nearly balanced, which explains why it is an efficient single-layer electroluminescent device. On the basis of the large second-order polarizability value and high transparency, this compound has the possibility to be an excellent second-order nonlinear optical material. The main origin of this large second-order nonlinear optical response is charge transfer from the triphenylamine group to (dppy)BF.

Journal Article↗

PubMed2006

A quantitative trait locus analysis of natural genetic variation for Drosophila melanogaster oxidative stress survival.

Little is known about natural genetic variation for survival under oxidative stress conditions or whether genetic variation for oxidative stress survival is associated with that for life-history traits. We have investigated survival in a high-oxygen environment at 2 adult densities using a set of recombinant inbred lines (RILs) isolated from a natural population of Drosophila melanogaster. Female and male oxidative stress survival was highly correlated. Quantitative trait loci (QTLs) for oxidative stress survival were identified on both autosomes. These QTLs were sometimes sex or density specific but were most often not. QTLs were identified that colocalize to the same region of the genome as longevity in other studies using the same set of RILs. We also determined early-age egg production and found QTLs for this trait, but there was no support for an association between oxidative stress survival and egg production.

Age Factors↗

PubMed2006

Synthesis and assembly with mesoporous silica MCM-48 of platinum(II) porphyrin complexes bearing carbazyl groups: spectroscopic and oxygen sensing properties.

The synthesis and spectroscopic characterization of a series of luminescent platinum meso-tetrakis{3,5-di[(N-carbazyl)n-alkyloxyphenyl]}porphyrin (Pt-8Cn-TPP, n-alkyl = (CH2)n, n = 4, 6, and 8) are presented. The protonated platinum porphyrins ([Pt-8Cn-TPPH8]8+) were assembled with mesoporous silica MCM-48 resulting in the assembly materials [Pt-8Cn-TPPH8]8+/MCM-48. The luminescence of [Pt-8Cn-TPPH8]8+/MCM-48 can be extremely quenched by molecular oxygen with very high sensitivity (I0/I100 > 5000) and rapid response time (0.04 s) suggesting that the [Pt-8Cn-TPPH8]8+/MCM-48 system can be employed to develop high performance oxygen sensors. Among this assembly system, [Pt-8C8-TPPH8]8+/MCM-48 exhibits the highest sensitivity. Even if the concentration of oxygen is 0.1%, the luminescence intensity of [Pt-8C8-TPPH8]8+/MCM-48 can be quenched by 86%.

Journal Article↗

PubMed2006

CD4+ T regulatory cell induction and function in transplant recipients after CD154 blockade is TLR4 independent.

Although the role of CD4(+) T regulatory cells (Treg) in transplantation tolerance has been established, putative mechanisms of Treg induction and function in vivo remain unclear. TLR4 signaling has been implicated in the regulation of CD4(+)CD25(+) Treg functions recently. In this study, we first examined the role of recipient TLR4 in the acquisition of operational CD4(+) Treg following CD154 blockade in a murine cardiac transplant model. Then, we determined whether TLR4 activation in allograft tolerant recipients would reverse alloimmune suppression mediated by CD4(+) Treg. We document that donor-specific immune tolerance was readily induced in TLR4-deficient recipients by a single dose of anti-CD154 mAb, similar to wild-type counterparts. The function and phenotype of CD4(+) Treg in both wild-type and TLR4 knockout long-term hosts was demonstrated by a series of depletion experiments examining their ability to suppress the rejection of secondary donor-type test skin grafts and to inhibit alloreactive CD8(+) T cell activation in vivo. Furthermore, TLR4 activation in tolerant recipients following exogenous LPS infusion in conjunction with donor-type skin graft challenge, failed to break Treg-mediated immune suppression. In conclusion, our data reveals a distinctive property of CD4(+) Treg in tolerant allograft recipients, whose induction and function are independent of TLR4 signaling.

Animals↗

PubMed2006

The timing of cortical neurogenesis is encoded within lineages of individual progenitor cells.

In the developing cerebral cortex, neurons are born on a predictable schedule. Here we show in mice that the essential timing mechanism is programmed within individual progenitor cells, and its expression depends solely on cell-intrinsic and environmental factors generated within the clonal lineage. Multipotent progenitor cells undergo repeated asymmetric divisions, sequentially generating neurons in their normal in vivo order: first preplate cells, including Cajal-Retzius neurons, then deep and finally superficial cortical plate neurons. As each cortical layer arises, stem cells and neuroblasts become restricted from generating earlier-born neuron types. Growth as neurospheres or in co-culture with younger cells did not restore their plasticity. Using short-hairpin RNA (shRNA) to reduce Foxg1 expression reset the timing of mid- but not late-gestation progenitors, allowing them to remake preplate neurons and then cortical-plate neurons. Our data demonstrate that neural stem cells change neuropotency during development and have a window of plasticity when restrictions can be reversed.

Animals↗

PubMed2006

Pi-conjugated aromatic enynes as a single-emitting component for white electroluminescence.

By use of the organolanthanide catalysts Me2Si(C5Me4)(NAr)Lu(CH2SiMe3)(THF) and (C5Me5)2LaCH(SiMe3)2, carbazole-substituted phenyl enynes (Z)-CPEY and (E)-CPEY were synthesized, respectively, with excellent regio- and stereoselectivity through the catalytic dimerization of the corresponding terminal alkyne. These new pi-conjugated compounds, in particular, the (E)-enyne isomer (E)-CPEY, act as an excellent single-emitting component for white organic light-emitting devices (WOLEDs), as a result of combination of the blue emission from an isolated molecule with the longer-wavelength emissions (green and orange-red) from excimers. The (E)-CPEY-based double-layer device emitted almost pure white light with CIE coordinates of (0.32, 0.33), maximum brightness of 1395 cd m-2, and maximum current efficiency of 2.07 cd A-1. This is perhaps the purest white emission ever reported for a single-emitting-component WOLED. The quality of the white emission remained almost unchanged under varying driving voltages, demonstrating an advantageous potential of single-emitting-component WOLEDs.

Journal Article↗

PubMed2006

ACE2 orthologues in non-mammalian vertebrates (Danio, Gallus, Fugu, Tetraodon and Xenopus).

Angiotensin-converting enzyme 2 (ACE2), a newly identified member in the renin-angiotensin system (RAS), acts as a negative regulator of ACE. It is mainly expressed in cardiac blood vessels and the tubular epithelia of kidneys and abnormal expression has been implicated in diabetes, hypertension and heart failure. The mechanism and physiological function of this zinc metallopeptidase in mammals are not yet fully understood. Non-mammalian vertebrate models offer attractive and simple alternatives that could facilitate the exploration of ACE2 function. In this paper we report the in silico analysis of Ace2 genes from the Gallus (chicken), Xenopus (frog), Fugu and Tetraodon (pufferfish) genome assembly databases, and from the Danio (zebrafish) cDNA library. Exon ambiguities of Danio and Xenopus Ace2s were resolved by RT-PCR and 3'RACE. Analyses of the exon-intron structures, alignment, phylogeny and hydrophilicity plots, together with the conserved synteny among these vertebrates, support the orthologous relationship between mammalian and non-mammalian ACE2s. The putative promoters of Ace2 from human, Tetraodon and Xenopus tropicalis drove the expression of enhanced green fluorescent protein (EGFP) specifically in the heart tissue of transgenic Xenopus thus making it a suitable model for future functional genomic studies. Additionally, the search for conserved cis-elements resulted in the discovery of WGATAR motifs in all the putative Ace2 promoters from 7 different animals, suggesting a possible role of GATA family transcriptional factors in regulating the expression of Ace2.

Angiotensin-Converting Enzyme 2↗

PubMed2006

Plasma membrane ion permeability induced by mutant alpha-synuclein contributes to the degeneration of neural cells.

Mutations in alpha-synuclein cause some cases of familial Parkinson's disease (PD), but the mechanism by which alpha-synuclein promotes degeneration of dopamine-producing neurons is unknown. We report that human neural cells expressing mutant alpha-synuclein (A30P and A53T) have higher plasma membrane ion permeability. The higher ion permeability caused by mutant alpha-synuclein would be because of relatively large pores through which most cations can pass non-selectively. Both the basal level of [Ca2+]i and the Ca2+ response to membrane depolarization are greater in cells expressing mutant alpha-synuclein. The membrane permeable Ca2+ chelator BAPTA-AM significantly protected the cells against oxidative stress, whereas neither L-type (nifedipine) nor N-type (omega-conotoxin-GVIA) Ca2+ channel blockers protected the cells. These findings suggest that the high membrane ion permeability caused by mutant alpha-synuclein may contribute to the degeneration of neurons in PD.

Calcium↗

PubMed2006

Synthesis, structures, and luminescent properties of phenol-pyridyl boron complexes.

Syntheses of the four mixed phenol-pyridine derivatives 1,6-bis(2-hydroxyphenyl)pyridyl boron naphthalene (1), 1,6-bis(2-hydroxy-5-methylphenyl)pyridyl boron naphthalene (2), 1,6-bis(2-hydroxyphenyl)pyridyl boron 2-methoxylbenzene (3), and 1,6-bis(2-hydroxy-5-methylphenyl)pyridyl boron 2-methoxylbenzene (4) are reported. The structures of the boron compounds 1, 3, and 4 were determined by single-crystal X-ray diffraction. The molecular packing is characterized by intermolecular pi...pi and hydrogen-bonding interactions. DSC analysis demonstrates that 1 and 2 have good thermal stability with higher glass transition temperatures (Tg) and melting points (Tm) than 3 and 4. Boron complexes 1-4 display bright blue luminescence in solution and the solid state. White and blue electroluminescent (EL) devices were fabricated successfully using these boron compounds.

Boron Compounds↗

PubMed2006

Recombinant tegumental protein Shistosoma japonicum very lowdensity lipoprotein binding protein as a vaccine candidate against Schistosoma japonicum.

A polyhistidine-tagged recombinant tegumental protein Schistosoma japonicum very lowdensity lipoprotein binding protein (SVLBP) from adult Schistosoma japonicum was expressed in Escherichia coli. The affinity purified rSVLBP was used to vaccinate mice. The worm numbers and egg deposition recovered from the livers and veins of the immunized mice were 33.5% and 47.6% less than that from control mice, respectively (p<0.05). There was also a marked increase in the antibody response in vaccinated mice: the titer of IgG1 and IgG2a, IgG2b in the vaccinated group was significantly higher than that in the controls (>1:6,400 in total IgG). In a comparison of the reactivity of sera from healthy individuals and patients with rSVLBP, recognition patterns against this parasite tegumental antigen varied among different groups of the individuals. Notably, the average titres of anti-rSVLBP antibody in sera from faecal egg-negative individuals was significantly higher than that in sera from the faecal egg-positives, which may be reflect SVLBP-specific protection. These results suggested that the parasite tegumental protein SVLBP was a promising candidate for further investigation as a vaccine antigen for use against Asian schistosomiasis.

Animals↗

PubMed2006

Evidence that caspase-1 is a negative regulator of AMPA receptor-mediated long-term potentiation at hippocampal synapses.

Best known for their pivotal role in a form of programmed cell death called apoptosis, caspases may also function in more subtle physiological processes. Caspases are present in synapses and dendrites of neurons where they can be activated in response to glutamate receptor stimulation and calcium influx. Here we tested the hypothesis that caspase-1 plays a role in modulating long-term potentiation (LTP) at hippocampal synapses. We provide evidence that caspase-1 plays a role in regulating alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated calcium influx and synaptic plasticity in the hippocampus. LTP of excitatory postsynaptic potentials at CA1 synapses was significantly enhanced when hippocampal slices were treated with either a pan-caspase inhibitor or a selective inhibitor of caspase-1, but not by an inhibitor of caspase-6. Inhibition of caspase-1 significantly enhanced the AMPA current-mediated component of LTP without affecting the N-methyl-D-aspartate current-mediated component. Calcium responses to AMPA were enhanced in hippocampal neurons treated with a caspase-1 inhibitor suggesting that caspase-1 normally functions to reduce AMPA receptor-mediated calcium influx. These findings suggest that, by selectively reducing AMPA currents and calcium influx, caspase-1 functions as a negative regulator of LTP at hippocampal synapses.

Animals↗

PubMed2006

Catalytic cracking of large molecules over hierarchical zeolites.

A hierarchical zeolite catalyst was synthesized by transforming the skeletons of a bimodal pore silica gel into a zeolite through a steam-assisted conversion method, and shows high catalytic activity and a long catalyst lifetime for catalytic cracking of large molecules.

Journal Article↗

PubMed2006

Di- and tetranuclear metal complexes with phenoxo bridges: synthesis, structures, and photoluminescent and electroluminescent properties.

Dinuclear and tetranuclear copper 2,6-bis(2-hydroxyphenyl)pyridine (H(2)L) complexes Cu2(L)2(py)2 (1) and Cu4(L)4(DMF) (2) were synthesized. The complexes 1 and 2 were characterized by elemental analyses, mass spectrometry, and single-crystal X-ray diffraction analyses. 1 crystallizes in the monoclinic space group P2(1)/n with a = 13.330(2) Angstroms, b = 9.361(1) Angstroms, c = 14.676(1) Angstroms, beta = 100.94(1) degrees, V = 1798.1(3) Angstroms(3), and Z = 2. 2 crystallizes in the monoclinic space group P2(1)/n with a = 13.360(1) Angstroms, b = 14.884(1) Angstroms, c = 15.462(2) Angstroms, beta = 97.50(4) degrees, V = 3048.4(1) Angstroms(3), and Z = 2. Tetranuclear zinc complex Zn4(L)4(py)4 (3) was prepared and characterized by X-ray diffraction. 3 crystallizes in the triclinic space group P with a = 13.770(1) Angstroms, b = 15.465(1) A, c = 16.409(2) Angstroms, alpha = 88.877(9) degrees, beta = 88.035(4) degrees, gamma = 82.956(3) degrees, V = 3465.6(5) Angstroms(3), and Z = 2. The di- and tetranuclear complexes 1-3contain phenoxo bridges. 1 is a dinuclear complex with two Cu(II) centers, two py ligands, and two L ligands, and each L ligand donates its pyridyl ring and one of the phenolate groups to one metal and shares the other phenolate group between both metals, affording a Cu(2)(mu-O)(2) core. 2, in contrast, is a tetranuclear complex with four Cu(II) centers and four L ligands. Two of the L ligands have the same coordination mode as 1, and the other two L ligands donate their pyridyl rings to one metal and share both phenolate groups between four metals, resulting in three four-membered Cu2(mu-O)2 rings, which joined each other and showed great distortion from planarity. 3 is a tetranuclear complex with four Zn(II) centers, four pyridine ligands, and four L ligands, and the L ligands have the same coordination modes as those of 2. Single-crystal X-ray analysis showed that hydrogen-bonding and pi-pi stacking interactions exist in complexes 1 and 2 resulting in two- and three-dimensional molecular arrangements, and the parallel arrangement of the ligand in the crystal of complex 3 resulted in a close inter- and intramolecular pi-pi interactions. Investigation of the crystals, as well as an amorphous thin film and powder of 3, by photoluminescence (PL) allowed the effect of the molecular packing on the emission properties to be elucidated. Furthermore, the electroluminescent (EL) properties of 3 were examined by fabricating a multilayer device with structure of [ITO/NPB/(ZnL)(n)/Alq3/LiF/Al] (NPB = N,N'-bis(alpha-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine, Alq3 = tris(8-hydroxyquinolinato)aluminum).

Journal Article↗

PubMed2006

Nuclear envelope dystrophies show a transcriptional fingerprint suggesting disruption of Rb-MyoD pathways in muscle regeneration.

Mutations of lamin A/C (LMNA) cause a wide range of human disorders, including progeria, lipodystrophy, neuropathies and autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD). EDMD is also caused by X-linked recessive loss-of-function mutations of emerin, another component of the inner nuclear lamina that directly interacts with LMNA. One model for disease pathogenesis of LMNA and emerin mutations is cell-specific perturbations of the mRNA transcriptome in terminally differentiated cells. To test this model, we studied 125 human muscle biopsies from 13 diagnostic groups (125 U133A, 125 U133B microarrays), including EDMD patients with LMNA and emerin mutations. A Visual and Statistical Data Analyzer (VISDA) algorithm was used to statistically model cluster hierarchy, resulting in a tree of phenotypic classifications. Validations of the diagnostic tree included permutations of U133A and U133B arrays, and use of two probe set algorithms (MAS5.0 and MBEI). This showed that the two nuclear envelope defects (EDMD LMNA, EDMD emerin) were highly related disorders and were also related to fascioscapulohumeral muscular dystrophy (FSHD). FSHD has recently been hypothesized to involve abnormal interactions of chromatin with the nuclear envelope. To identify disease-specific transcripts for EDMD, we applied a leave-one-out (LOO) cross-validation approach using LMNA patient muscle as a test data set, with reverse transcription-polymerase chain reaction (RT-PCR) validations in both LMNA and emerin patient muscle. A high proportion of top-ranked and validated transcripts were components of the same transcriptional regulatory pathway involving Rb1 and MyoD during muscle regeneration (CRI-1, CREBBP, Nap1L1, ECREBBP/p300), where each was specifically upregulated in EDMD. Using a muscle regeneration time series (27 time points) we develop a transcriptional model for downstream consequences of LMNA and emerin mutations. We propose that key interactions between the nuclear envelope and Rb and MyoD fail in EDMD at the point of myoblast exit from the cell cycle, leading to poorly coordinated phosphorylation and acetylation steps. Our data is consistent with mutations of nuclear lamina components leading to destabilization of the transcriptome in differentiated cells.

Biopsy↗

PubMed2006

Clinical application of self-expanding metallic stent in the management of acute left-sided colorectal malignant obstruction.

AIM: To summarize our experience with the application of self-expanding metallic stent (SEMS) in the management of acute left-sided colorectal malignant obstruction. METHODS: A retrospective chart review of all patients undergoing placement of SEMS between April 2000 and January 2004 was performed. RESULTS: Insertion of SEMS was attempted in 26 patients under fluoroscopic guidance with occasional endoscopic assistance. The sites of lesions were located in splenic flexure of two patients, left colon of seven patients, sigmoid colon of eight patients and rectum of nine patients. The intended uses of SEMS were for palliation in 7 patients and as a bridge to elective surgery in 19 patients. In the latter group, placement of SEMS allowed for preoperative systemic and bowel preparation and the following one-stage anastomosis. Successful stent placement was achieved in 22 (85%) of the 26 patients. The clinical bowel obstruction resolved 24 hours after successful stent placement in 21 (95%) patients. Three SEMS-related minor complications occurred, two stents migrated and one caused anal pain. CONCLUSION: SEMS represents an effective and safe tool in the management of acute malignant colorectal obstruction. As a bridge to surgery, SEMS can provide time for systematic support and bowel preparation and obviate the need for fecal diversion or on-table lavage. As a palliative measure, SEMS can eliminate the need for emergent colostomy.

Acute Disease↗

PubMed2006

Wound repair and proliferation of bronchial epithelial cells enhanced by bombesin receptor subtype 3 activation.

The present study was designed to investigate the role of bombesin receptor subtype 3 (BRS-3) in airway wound repair. The results showed that: (1) There was few expression of BRS-3 mRNA in the control group. In contrast, the expression of BRS-3 mRNA was gradually increased in the early 2 days, and peaked on the fourth day, and then decreased in the ozone-stressed AHR animal. BRS-3 mRNA was distributed in the ciliated columnar epithelium, monolayer columnar epithelium cells, scattered mesenchymal cells and Type II alveolar cells; (2) The wound repair and proliferation of bronchial epithelial cells (BECs) were accelerated in a concentration-dependent manner by BRS-3 activation with P3513, which could be inhibited by PKA inhibitor H89. The study demostrated that activation of BRS-3 may play an important role in wound repair of AHR.

Animals↗

PubMed2006

Optimized multilayer perceptrons for molecular classification and diagnosis using genomic data.

MOTIVATION: Multilayer perceptrons (MLP) represent one of the widely used and effective machine learning methods currently applied to diagnostic classification based on high-dimensional genomic data. Since the dimensionalities of the existing genomic data often exceed the available sample sizes by orders of magnitude, the MLP performance may degrade owing to the curse of dimensionality and over-fitting, and may not provide acceptable prediction accuracy. RESULTS: Based on Fisher linear discriminant analysis, we designed and implemented an MLP optimization scheme for a two-layer MLP that effectively optimizes the initialization of MLP parameters and MLP architecture. The optimized MLP consistently demonstrated its ability in easing the curse of dimensionality in large microarray datasets. In comparison with a conventional MLP using random initialization, we obtained significant improvements in major performance measures including Bayes classification accuracy, convergence properties and area under the receiver operating characteristic curve (A(z)). SUPPLEMENTARY INFORMATION: The Supplementary information is available on http://www.cbil.ece.vt.edu/publications.htm

Biomarkers, Tumor↗

PubMed2006

Transient improvement in cognitive function and synaptic plasticity in rats following cancer chemotherapy.

BACKGROUND: Cancer chemotherapy has been associated with cognitive impairment. Several issues complicate such findings including the patients' health, use of multiple chemotherapeutic agents, and proper assessment of cognition. To control these factors, we conducted cognitive studies in female rats receiving cyclophosphamide or 5-fluorouracil (5FU). METHODS: Young (7 months) female Fischer-344 rats received five injections of cyclophosphamide (100 mg/kg), 5FU (150 mg/kg), or saline i.p. every 4 weeks for a total of 18 weeks. Aged (18 months) female Fischer-344 rats were treated with cyclophosphamide (80 mg/kg i.p.) for 16 weeks. After 8 to 10 weeks of recovery, rats were tested in two maze learning tasks, the Morris water maze and the Stone 14-unit T-maze. Neuronal synaptic function was assessed by examining long-term potentiation (LTP) in hippocampal slices obtained from young cyclophosphamide-treated rats. RESULTS: Despite the toxic effects induced by chemotherapy, cyclophosphamide- and 5FU-treated rats showed significantly better maze performance compared with controls. Following 29 to 42 weeks of recovery from chemotherapy, no significant effects were observed on maze performance. In aged rats, cyclophosphamide treatment for 14 weeks also produced toxicity, but no impairment in Stone maze learning after 16 weeks of recovery. When assessed during cyclophosphamide treatment, evidence of impaired LTP emerged; however, with 8 weeks of recovery following five cyclophosphamide treatments, we observed enhanced LTP. CONCLUSION: Despite toxicity accompanying chemotherapy, no evidence of impaired cognitive performance emerged after recovery. Indeed, following 7 to 9 weeks of recovery, we noted evidence of improved learning and LTP.

Age Factors↗