Biomedical subjects

G Y Xu

Publications and source records attributed to G Y Xu.

At least 19 recordsLinked to original sources

PubMed2006

Molecular cloning and expression of the duplicated thyroid hormone responsive spot 14 (THRSP) genes in ducks.

Thyroid hormone responsive Spot 14 (THRSP) is suggested as a transcription factor involved in the regulation of adipogenic enzymes by 3 thyroid response elements in the promoter region. In the chicken genome, THRSP gene was identified to duplicate into 2 paralogs, THRSPalpha and THRSPbeta. In the current study, cDNA sequences of the duplicated duck THRSP genes were cloned by real-time PCR and rapid amplification of cDNA ends. Duck THRSPalpha and THRSPbeta were predicted to encode peptides with 133 amino acids, which had 74 and 68% sequence identity at cDNA level, 78 and 74% identity at amino acid level to the chicken counterparts, respectively. A high percentage (73.1%) of G and C nucleotides were found in the 3' untranslated region of duck THRSPbeta cDNA. Although a low similarity of peptide composition was shared between ducks and mammals, and a moderate similarity was shared between ducks and chickens, many predicted properties of THRSP, including the pI, subcellular localization and functional domains seemed to be highly conserved. The present study demonstrated that the duck THRSP gene duplicates into the 2 paralogs as in chickens. Phylogenetic analysis indicated that the duplication for THRSP paralogs appeared to have taken place preceding the chicken-duck split, and the diverging rate between THRSP paralogs seemed faster in the chicken genome than that in the duck genome. Expression analysis by real-time quantitative PCR showed that THRSP paralogs in ducks were more actively transcribed in fat tissues (i.e., s.c. fat and abdominal fat) than in liver, and the mRNA concentrations of THRSPbeta were higher than that of THRSPalpha in liver and s.c. fat.

Amino Acid Sequence↗

PubMed2006

A study on eggshell pigmentation: biliverdin in blue-shelled chickens.

Biliverdin is an important pigment in the eggshell of chickens and other avian species. Determination of the biosynthesis site for biliverdin is essential for understanding the biochemical process and genetic basis of eggshell pigmentation. Either blood or the shell gland could be the biosynthesis site of eggshell biliverdin. A segregation population with full-sib sisters genotyped Oo and oo, which laid blue-shelled eggs and light brown eggs, respectively, was constructed in a native Chinese chicken breed. Ultraviolet spectrophotometry and HPLC were used to determine the biliverdin concentration in eggshells, blood, bile, excreta, and shell gland of both groups of chickens. Biliverdin content was significantly different between egg shells of blue-shelled and brown-shelled chickens (P < 0.01). Blood and bile were tested 3 to 4 h before oviposition, and excreta was tested randomly. Results showed no significant difference in biliverdin concentration in blood, bile, and excreta between the 2 groups. In the shell gland, the biliverdin contents for the blue-shelled and brown-shelled chickens were 8.25 +/- 2.55 and 1.29 +/- 0.12 nmol/g, respectively, which showed a significant difference (P < 0.01). Our results demonstrated that blood is not the biosynthesis site of the shell biliverdin. Biliverdin is most likely synthesized in the shell gland and then deposited onto the eggshell of chickens.

Animals↗

PubMed2005

Aggregation between xanthan and nonyphenyloxypropyl beta-hydroxyltrimethylammonium bromide in aqueous solution: MesoDyn simulation and binding isotherm measurement.

The aggregation behavior of nonyphenyloxypropyl beta-hydroxyltrimethylammonium bromide (C9phNBr) and xanthan (XC) in aqueous solution was investigated by MesoDyn density functional simulation and binding isotherm measurement. The process of aggregate formation and the aggregate morphology are reported. The formation of aggregates includes three stages and the morphology of XC-C9phNBr aggregates is rodlike or ellipsoidal. The effects of temperature and XC concentration on the aggregation are analyzed. Results indicate that the formation of aggregates is an exothermic process, and their formation becomes more difficult and the formation rate decreases with increasing temperature. The formation of aggregates is also related to XC concentration, and it becomes much more difficult when the concentration of XC is higher than 20 vol %. The simulation results agree with binding isotherms of C9phNBr to XC obtained via the potentiometric titration method, which shows a typical cooperative binding between C9phNBr and XC.

Journal Article↗

PubMed2005

Exogenous Bcl-xL fusion protein spares neurons after spinal cord injury.

Spinal cord injury (SCI) induces neuronal death, including apoptosis, which is completed within 24 hr at and around the impact site. We identified early proapoptotic transcriptional changes, including upregulation of proapoptotic Bax and downregulation of antiapoptotic Bcl-xL, Bcl-2, and Bcl-w, using Affymetrix DNA microarrays. Because Bcl-xL is the most robustly expressed antiapoptotic Bcl-2 molecule in adult central nervous system, we decided to characterize better the effect of SCI on Bcl-xL expression. We found Bcl-xL expressed robustly throughout uninjured spinal cord in both neurons and glia cells. We also found Bcl-xL localized in different cellular compartments: cytoplasmic, mitochondrial, and nuclear. Bcl-xL protein levels decreased in the cytoplasm and mitochondria 2 hr after SCI and persisted for 24 hr. To test the contribution of proapoptotic decreases in Bcl-xL to neuronal death, we augmented endogenous Bcl-xL levels by administering Bcl-xL fusion protein (Bcl-xL FP) into injured spinal cords. Bcl-xL FP significantly increased neuronal survival, suggesting that SCI-induced changes in Bcl-xL contribute considerably to neuronal death. Because Bcl-xL FP increases survival of dorsal horn neurons and ventral horn motoneurons, it could become clinically relevant in preserving sensory and motor functions after SCI.

Animals↗

PubMed2005

Association of polymorphisms for prolactin and prolactin receptor genes with broody traits in chickens.

Prolactin (PRL) is generally accepted as crucial to the onset and maintenance of broodiness in avian species. The prolactin receptor (PRLR) plays an important role in the PRL signal transduction cascade. Two candidate genes, PRL and PRLR, were screened for polymorphisms in the chicken, and their genetic effects on broodiness were evaluated. Pedigreed hens (n = 155) of the Blue-shell chicken, a Chinese local breed, were observed for phenotypic broody traits including nesting days, broody days, repeats of broody cycles, and duration of broodiness. For polymorphism analysis, White Leghorns, Hy-Line brown egg layers, Avian broilers, and some other Chinese local breeds were included. Fifteen sets of primers were used to amplify the nucleotide sequences of the promotor of PRL and exons of PRLR. The PCR products were screened for polymorphisms using single-stranded conformational polymorphism protocol. Sequencing revealed a 24-bp insertion occurring in the promotor, -377 approximately -354, of PRL (GenBank accession no. AB011434). A single nucleotide polymorphism (SNP), A9026G (GenBank accession no. AY237377), in exon 3 of PRLR was also detected, which led to a nucleotide transition in the 5'-untranslated region (5'-UTR) of PRLR cDNA. Two SNP, T14771C and G14820A (GenBank accession no. AY237376), were detected in exon 6 of the PRLR. The T14771C transition led to an amino acid variation, Leu340Ser, in PRLR, whereas the G14820A transition was a synonymous mutation. An association analysis showed that the genetic polymorphisms at PRLR3 and PRLR6 were not related to broodiness (P > 0.05), whereas the individuals without the insertion sequence at PRLpro2 were associated with broody traits (P < 0.05) and the incidence (>30%) of typical broody of genotypes +/- and -/- was higher (P < 0.01) than that of +/+. In addition, all White Leghorns were +/+ for PRLpro2, whereas local breeds with very strong broodiness were nearly all -/-. Homozygous insertion of the 24-bp sequence in the PRL promoter may decrease the expression of PRL, leading to nonbroodiness. The results suggested that PRLpro2 could be a genetic marker in breeding against broodiness in chickens.

Animals↗

PubMed2005

Heritabilities and genetic and phenotypic correlations of egg quality traits in brown-egg dwarf layers.

Albumen height, albumen weight (AW), eggshell color (ESC), eggshell index, eggshell strength, eggshell thickness, eggshell weight (ESW), egg weight (EW), Haugh units, and yolk weight (YW) were measured in 2,272 eggs collected 3 d sequentially from 920 brown-egg dwarf layers caged individually. The restricted maximum likelihood procedure was applied to estimate heritabilities and genotypic and phenotypic correlations for these egg quality traits. Heritabilities of albumen height, AW, ESC, eggshell index, eggshell strength, eggshell thickness, ESW, EW, Haugh units, and YW were 0.51, 0.59, 0.46, 0.40, 0.24, 0.34, 0.64, 0.63, 0.41, and 0.45, respectively. The genetic correlations between EW and AW, YW, and ESW were high ranging from 0.67 to 0.97, whereas those for ESC with external and internal egg quality traits were low ranging from -0.23 to 0.13. Thus although heritabilities for these traits were moderate to high, genetic correlations with ESC were low, suggesting a minor relationship between shell color and physical attributes of the shell as well as internal egg quality in brown-egg dwarf layers.

Animals↗

PubMed2004

Characterization and demulsification of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers.

Four poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers with different molecular weights and PPO/PEO composition ratios were synthesized. The characterization of the PEO-PPO-PEO triblock copolymers was studied by surface tension measurement, UV-vis spectra, and surface pressure method. These results clearly showed that the CMC of PEO-PPO-PEO was not a certain value but a concentration range, in contrast to classical surfactant, and two breaks around CMC were reflected in both surface tension isotherm curves and UV-vis absorption spectra. The range of CMC became wider with increasing PPO/PEO composition ratio. Surface pressure Pi-A curves revealed that the amphiphilic triblock copolymer PEO-PPO-PEO molecule was flexible at the air/water interface. We found that the minimum area per molecule at the air/water interface increased with the proportion of PEO chains. The copolymers with the same mass fractions of PEO had similar slopes in the isotherm of the Pi-A curve. From the demulsification experiments a conclusion had been drawn that the dehydration speed increased with decreased content of PEO, but the final dehydration rate of four demulsifiers was approximate. We determined that the coalescence of water drops resulted in the breaking of crude oil emulsions from the micrograph.

Emulsions↗

PubMed2001

Change in excitability and phenotype of substance P and its receptor in cat Abeta sensory neurons following peripheral inflammation.

The effect of peripheral inflammation on spontaneous firing and level of substance P (SP) and its receptor in electrophysiologically identified cat Abeta neurons of dorsal root ganglion (DRG) was studied in vivo using a combination of intracellular recording, dye injection and immunohistochemical techniques. Following injection of carrageenan (Carg) into cat hindpaw, the number of Abeta neurons with spontaneous firing was enhanced significantly (42.9%, n=182) in comparison with control (16.8%, n=149, P<0.01). DRG Abeta neurons became less depolarized 2-4 h following Carg injection. After identifying the cell properties, Lucifer Yellow was injected and SP-like immunoreactivity (SP-LI) was then detected. A total of 17% of Abeta sensory neurons exhibited SP-LI in inflammatory cat. We also found in rat DRGs that the number of SP-LI positive large cells (>35 microm) was also significantly increased in Carg-treated DRG (11.8+/-1.2, n=8) compared with untreated DRG (1.8+/-0.8, n=8, P<0.01). In control cat, the topical use of SP in DRG did not induce any response of Abeta neurons. However, in Carg-treated cat, SP depolarized the membrane potential in most Abeta neurons (68.2%, n=22). L668,169, an antagonist of SP receptor, completely blocked the SP-induced responses. Furthermore, repeated application of SP did not induce obvious desensitization of Abeta neurons. These data suggest that peripheral inflammation increased the excitability, SP level and sensitivity of SP receptor of Abeta neurons. Therefore, we concluded that Abeta sensory neurons appear to contribute to inflammatory allodynia.

Action Potentials↗

PubMed2001

Solution structure of the tumor necrosis factor receptor-1 death domain.

Tumor necrosis factor receptor-1 death domain (TNFR-1 DD) is the intracellular functional domain responsible for the receptor signaling activities. The solution structure of the R347K mutant of TNFR-1 DD was solved by NMR spectroscopy. A total of 20 structures were calculated by means of hybrid distance geometry-simulated annealing using a total of 1167 distance constraints and 117 torsion angle constraints. The atomic rms distribution about the mean coordinate positions for the 20 structures for residues composing the secondary structure region is 0.40 A for the backbone atoms and 1.09 A for all atoms. The structure consists of six antiparallel alpha-helices arranged in a similar fashion to the other members of the death domain superfamily. The secondary structure and three-dimensional structure of R347K TNFR1-DD are very similar to the secondary structure and deduced topology of the R347A TNFR1-DD mutant. Mutagenesis studies identified critical residues located in alpha2 and part of alpha3 and alpha4 that are crucial for self-interaction and interaction with TRADD. Structural superposition with previously solved proteins in the death domain superfamily reveals that the major differences between the structures reside in alpha2, alpha3, and alpha4. Interestingly, these regions correspond to the binding sites of TNFR1-DD, providing a structural basis for the specificity of death domain interactions and its subsequent signaling event.

Amino Acid Sequence↗

PubMed2001

Solution structure of B. subtilis acyl carrier protein.

BACKGROUND: Acyl carrier protein (ACP) is a fundamental component of fatty acid biosynthesis in which the fatty acid chain is elongated by the fatty acid synthetase system while attached to the 4'-phosphopantetheine prosthetic group (4'-PP) of ACP. Activation of ACP is mediated by holo-acyl carrier protein synthase (ACPS) when ACPS transfers the 4'-PP moiety from coenzyme A (CoA) to Ser36 of apo-ACP. Both ACP and ACPS have been identified as essential for E. coli viability and potential targets for development of antibiotics. RESULTS: The solution structure of B. subtilis ACP (9 kDa) has been determined using two-dimensional and three-dimensional heteronuclear NMR spectroscopy. A total of 22 structures were calculated by means of hybrid distance geometry-simulated annealing using a total of 1,050 experimental NMR restraints. The atomic rmsd about the mean coordinate positions for the 22 structures is 0.45 +/- 0.08 A for the backbone atoms and 0.93 +/- 0.07 A for all atoms. The overall ACP structure consists of a four alpha-helical bundle in which 4'-PP is attached to the conserved Ser36 that is located in alpha helix II. CONCLUSIONS: Structural data were collected for both the apo and holo forms of ACP that suggest that the two forms of ACP are essentially identical. Comparison of the published structures for E. coli ACP and actinorhodin polyketide synthase acyl carrier protein (act apo-ACP) from Streptomyces coelicolor A3(2) with B. subtilis ACP indicates similar secondary structure elements but an extremely large rmsd between the three ACP structures (>4.3 A). The structural difference between B. subtilis ACP and both E. coli and act apo-ACP is not attributed to an inherent difference in the proteins, but is probably a result of a limitation in the methodology available for the analysis for E. coli and act apo-ACP. Comparison of the structure of free ACP with the bound form of ACP in the ACP-ACPS complex reveals a displacement of helix II in the vicinity of Ser36. The induced perturbation of ACP by ACPS positions Ser36 proximal to coenzyme A and aligns the dipole of helix II to initiate transfer of 4'-PP to ACP.

Acyl Carrier Protein↗

PubMed2001

Identification and structural determination of a potent P-selectin inhibitor.

Small quantities of a potent P-selectin inhibitor, 2 (IC50 = 0.2 microM), were isolated and an initial structure proposed based on 1D proton NMR. A reterosynthetic analysis of the proposed structure led us to a total synthesis of 2. NMR studies using the 2-D homo-TOCSY and NOESY and 2-D hetero-HMQC helped to confirm the structure of 2.

Animals↗

PubMed2001

Involvement of metabotropic glutamate receptors in excitatory amino acid and GABA release following spinal cord injury in rat.

Spinal cord injury (SCI) leads to an increase in extracellular excitatory amino acid (EAA) concentrations resulting in glutamate receptor-mediated excitotoxic events. The glutamate receptors include ionotropic (iGluRs) and metabotropic (mGluR) receptors. Of the three groups of mGluRs, group-I activation can initiate intracellular pathways that lead to further transmitter release. Groups II and III mGluRs function mainly as autoreceptors to regulate neurotransmitter release. In an effort to examine the role of mGluRs in the increase in EAAs following SCI, we administered AIDA, a potent group-I mGluR antagonist immediately after injury. To determine subtype specific roles of the group-I mGluRs, we evaluated EAA release following LY 367385 (mGluR1 antagonist) and MPEP (mGluR5 antagonist) administration. To evaluate group-II and -III mGluRs we administered APDC (group-II agonist) and L-AP4 (group-III agonist) immediately following injury; additionally, we initiated treatment with CPPG (group-II/-III antagonist) and LY 341495 (group-II antagonist) 5 min prior to injury. Subjects were adult male Sprague-Dawley rats (225-250 g), impact injured at T10 with an NYU impactor (12.5 mm drop). Agents were injected into the epicenter of injury, amino acids where collected by microdialysis fibers inserted 0.5 mm caudal from the edge of the impact region and quantified by HPLC. Treatment with AIDA significantly decreased extracellular EAA and GABA concentrations. MPEP reduced EAA concentrations without affecting GABA. Combining LY 367385 and MPEP resulted in a decrease in EAA and GABA concentrations greater than either agent alone. L-AP4 decreased EAA levels, while treatment with LY 341495 increased EAA levels. These results suggest that mGluRs play an important role in EAA toxicity following SCI.

Animals↗

PubMed2001

Bcl-xL expression after contusion to the rat spinal cord.

After contusion-derived spinal cord injury, (SCI) there is localized tissue disruption and energy failure that results in early necrosis and delayed apoptosis, events that contribute to chronic central pain in a majority of patients. We assessed the extent of contusion-induced apoptosis of neurons in a known central pain-signaling pathway, the spinothalamic tract (STT), which may be a contributor to SCI-induced pain. We observed the loss of STT cells and localized increase of DNA fragmentation and cytoplasmic histone-DNA complexes, which suggested potential apoptotic changes among STT neurons after SCI. We also showed SCI-associated changes in the expression of the antiapoptotic protein Bcl-xL, especially among STT cells, consistent with the hypothesis that Bcl-xL regulates the extent of apoptosis after SCI. Apoptosis in the injured spinal cord correlated well with prompt decreases in Bcl-xL protein levels and Bcl-xL/Bax protein ratios at the contusion site. We interpret these results as evidence that regulation of Bcl-xL may play a role in neural sparing after spinal injury and pain-signaling function.

Animals↗

PubMed2001

IL-1 receptor antagonist prevents apoptosis and caspase-3 activation after spinal cord injury.

One of the consequences of cytokine-orchestrated inflammation after CNS trauma is apoptosis. Our hypothesis is that cell death in the spinal cord after injury results in part from increased synthesis and release of IL-1beta. Using a ribonuclease protection assay, we demonstrated that there is increased transient expression of IL-1beta mRNA and, by using IL-1beta protein ELISA assay, that there are increased IL-1beta protein levels in the contused rat spinal cord, initially localized to the impact region of the spinal cord (segment T8). Using an ELISA cell death assay, we showed that there is apoptosis in the spinal cord 72 h after injury, a finding that was confirmed by measuring caspase-3 activity, which also significantly increased at the site of injury 72 h after trauma. Treatment of the contused spinal cord at the site of injury with the IL-1 receptor antagonist (rmIL-lra, 750 ng/mL) for 72 h using an osmotic minipump completely abolished the increases in contusion-induced apoptosis and caspase-3 activity.

Animals↗

PubMed2001

[Study on the structural property of polysacchrides 139A--a kind of IL-1R antagonists from microorganism].

AIM: To study the structural property of the bioactive component from the fermentation broth of Streptomyces 139 which can inhibit IL-1R. METHODS: Polysaccharide 139A is extracted and purified by means of macroreticular resin Diaion HP-20, cation exchange and DEAE Sephadex A-25 chromatography. The sugar compositions were analyzed with GC, the linkage positions of 139A were determined by methylation and GC-MS. RESULTS: The bioactive component which can inhibit IL-1R is a kind of polysaccharides. CONCLUSION: The components of 139A repeat units are conjectured.

Gas Chromatography-Mass Spectrometry↗

PubMed2000

Fluorescence property on solutions of zwitterionic surfactant tetradecylbetaine in the presence of macromolecules.

The fluorescence property of zwitterionic surfactant tetradecylbetaine (C14BE) solutions in the presence of polyvinylpyrrolidone (PVPk30 and PVPk90), or Xanthan (Xc) have been investigated by steady-state fluorescence probe. The intensity ratio of the first and third peaks (I1/I3) of the monomer and that of the excimer to monomer (Ie/Im), and the aggregation number of the aggregates have been monitored. The results showed that C14BE/PVP and C14BE/Xc interactions mostly occur at the micelle surface. The C14BE clusters or micelles are bound to macromolecule chains by electrostatic force for PVP and by hydrogen-bonding for Xc, respectively.

Betaine↗

PubMed2000

Activation of silent mechanoreceptive cat C and Adelta sensory neurons and their substance P expression following peripheral inflammation.

The effect of inflammation on the excitability and the level of substance P (SP) in cat mechanoreceptive C and Adelta dorsal root ganglion (DRG) neurons were studied in vivo using intracellular recording and immunocytochemical techniques. Following injections of carrageenan (Carg) into the cat hindpaw, the percentage of C neurons exhibiting spontaneous activity increased from 7.2 to 20.7% and the percentage of Adelta neurons increased from 6.9 to 18.6%. In contrast to most cells from normal cats, which fired regularly below 10 Hz, many cells from Carg-treated cats fired at higher frequencies or in bursts. Inflammation (Carg treatment) also depolarized membrane potentials, increased membrane input resistance, caused the disappearance of inward rectifying currents and lowered the mean current thresholds of tibial nerve-evoked responses in DRG neurons. With inflammation, the percentage of C or Adelta neurons responding to low threshold mechanoreceptive stimuli increased (C neurons: normal, 13%; inflamed, 41%; Adelta neurons: normal, 13 %; inflamed, 39 %), while the percentage of C or Adelta neurons responding to high threshold mechanoreceptive stimuli remained unchanged. Some receptive field (RF)-responsive cells were injected with Lucifer Yellow and their SP immunoreactivity was determined. Following Carg treatment, substantially higher percentages of RF-responsive cells were SP positive (C neurons: normal, 35.7%; inflamed, 60%; Adelta neurons: normal, 18.2%; inflamed, 66.7%). These combined increases in the excitability of DRG neurons and SP-containing RF-responsive neurons could lead to sensitization of sensory neurons, thus contributing to the development of hyperalgesia.

Animals↗

PubMed2000

AIDA reduces glutamate release and attenuates mechanical allodynia after spinal cord injury.

Spinal cord injury (SCI) leads to an increase in extracellular excitatory amino acid (EAA) concentrations, resulting in glutamate receptor-mediated excitotoxicity and central sensitization. To test contributions of group I metabotropic glutamate receptors (mGluRs) in SCI induced release of glutamate and in behavioral outcomes of central sensitization following injury, we administered 1-aminoindan-1,5-dicarboxylic acid (AIDA; 0.1 nmol intraspinally), a potent group I mGluR antagonist, to rats immediately after spinal cord contusion injury. EAAs were collected by microdialysis and quantified using HPLC. AIDA significantly decreased extracellular glutamate but not aspartate concentrations and significantly attenuated the development of mechanical but not thermal allodynia. These results suggest mGluRs play an important role in injury-induced EAA release and in central sensitization following SCI.

Animals↗