Biomedical subjects

Y Xiao

Publications and source records attributed to Y Xiao.

At least 19 recordsLinked to original sources

PubMed2007

Development of indirect enzyme-linked immunosorbent assay with nucleoprotein as antigen for detection and quantification of antibodies against avian influenza virus.

Avian influenza (AI) is a serious infectious disease caused by avian influenza virus (AIV) belonging to type A Orthomyxovirus. In the present study, we developed an indirect enzyme-linked immunosorbent assay (ELISA) employing E. coli-expressed full-length nucleoprotein (NP) of H9N2 avian influenza virus for the detection and quantification of antibodies against AIV nucleoprotein. The NP-ELISA was compared with the AI agar gel propagation (AGP) test, haemagglutination inhibition (HI) test, and IDEXX-FlockChek ELISA using 263 sera. The NP-ELISA was significantly more sensitive than the AGP and HI tests, and showed 96.2% agreement ratio with IDEXX-FlockChek ELISA. With results obtained using the NP-ELISA, an ELISA titre (ET) prediction equation, with which the ELISA titres of a flock or individual chickens can be determined, was derived from a positive/negative (P/N) ratio standard curve. The NP-ELISA enables an alternative rapid serological diagnosis and is suitable for influenza A antibody screening, especially in species that harbour several influenza subtypes.

Animals↗

PubMed2006

Comparison of methods for total community DNA extraction and purification from compost.

The differences on DNA yield and purity of three different DNA extraction protocols were compared with regard to the use for PCR and other molecular analyses. Total DNA was extracted from compost by the three protocols, and then was purified by spin-bind cartridges after being precipitated by PEG8000. The detection performed on a nucleic acid and protein analyzer showed that all three methods produced high DNA yields. The agarose gel electrophoresis showed that the fragments of crude and purified DNA had a length of about 23 kb. A eubacterial 16S rRNA gene-targeted primer pair was used for PCR amplification, and full length 16S rDNAs were amplified from all the purified DNA samples. After being digested by restriction endonucleases, the restriction map of amplified rDNA showed identical genetic diversity. The products of PCR using primer pair GC341F and 907R were also used for denaturing gradient gel electrophoresis analysis. The results indicated that high-quality DNA was extracted from compost by the three protocols, and each of the protocols is adapted to extract microbial genome DNA from compost expediently and cheaply.

DNA↗

PubMed2006

Lattice dynamics of carbon chain inside a carbon nanotube.

Based on the density functional theory, we obtain the optimum geometry of carbon chain inside a carbon nanotube. The phonon spectrum and specific heat of such a chain and nanotube hybrid system are calculated in terms of lattice dynamics theory. Some new phonon branches that have been obtained come from the coupling vibrations of the nanotube and the chain. The bending and stretching modes of the chain appear at about 520 cm(-1)and 1935 cm(-1) at Gamma point, respectively. It is found that the softening of G modes results mainly from the chain induced variations in the bond length on nanotube, independent of van der Waals interaction, while the stiffening of radial breathing mode is developed by the competition between the two factors. In the low-frequency region, the vibrational density of states are very different from that of the bare nanotube. Its specific heat implies the underlying quantized phonon structures and much large thermal conductivity in the hybrid system. In addition, the chain-length dependent vibration modes are calculated, from which it is expected that a finite chain of about 14 carbon atoms in the nanotube may produce the experimental Raman peak at about 1850 cm(-1).

Journal Article↗

PubMed2006

A semi-stochastic model for Salmonella infection in a multi-group herd.

A multi-group semi-stochastic model is formulated to identify possible causes of why different strains of Salmonella develop so much variation in their infection dynamics in UK dairy herds. The model includes demography (managed populations) and various types of transmission: direct, pseudovertical and indirect (via free-living infectious units in the environment). The effects of herd size and epidemiological parameters on mean prevalence of infection and mean time until fade out are investigated. Numerical simulation shows that higher pathogen-induced mortality, shorter infectious period, more persistent immune response and more rapid removal of faeces result in a lower mean prevalence of infection, a shorter mean time until fade out, and a greater probability of fade out of infection within 600 days. Combining these results and those for the deterministic counterpart could explain differences in observed epidemiological patterns and help to identify the factors inducing the decline in reported cases of epidemic strains such as DT104 in cattle. We further investigate the effect of group structure on the probability of a major outbreak by using the stochastic threshold theory in homogeneous populations and that in heterogeneous populations. Numerical studies suggest that group structure makes major outbreaks less likely than would be the case in a homogeneous population with the same basic reproduction number. Moreover, some control strategies are suggested by investigating the effect of epidemiological parameters on the probability of an epidemic.

Animals↗

PubMed2006

Twenty-three novel HLA-B alleles identified during intermediate-resolution testing.

Twenty-three novel human leukocyte antigen-B alleles are described: B*070204, *0738, *0742, *0821, *130202, *1312, *1575, *1598, *1599, *270507, *2728, *350104, *3558, *3811, *3931, *3932, *4045, *4107, *420501, *4812, *510106, *5520, and *5616. Thirteen of the variants are single-nucleotide substitutions from their most homologous allele, eight resulting in amino acid changes (B*0742, *1312, *1598, *1599, *3558, *3931, *4107, and *5616) and five with silent substitutions (B*070204, *130202, *270507, *350104, and *510106). Three alleles (B*0738, *4812, and *5520) differ by five nucleotide changes, altering four amino acids. The remaining seven alleles differ from their most similar alleles by two to three nucleotides, altering from one to two amino acids.

Alleles↗

PubMed2006

Searching for HLA-DRB1*1206 in volunteer marrow donors in four US population groups.

The frequencies of DRB1*12 alleles were determined in four US population groups by DNA sequencing. Only DRB1*120101 (or DRB1*1206 or *1210) and DRB1*120201 alleles were identified, the latter primarily in the Asian American population. Additional testing of a subset of samples to detect the presence of DRB1*1206 found all of the alleles to be DRB1*120101 (or DRB1*1210). Retesting of six samples previously typed as DRB1*1206 found only DRB1*120101 (or DRB1*1210).

Black or African American↗

PubMed2005

Distribution of sorbed phenanthrene and pyrene in different humic fractions of soils and importance of humin.

Contributions of fulvic-humic acids (FA/HA) and humin (HM) to sorption of phenanthrene (PHE) and pyrene (PYR) in a soil were differentiated using a humic separation procedure after multi-concentration sorption experiments. It was found that the amount of solutes in FA/HA did not change significantly after 48 h, while that in HM increased continuously and slowly up to the end of the experimental period (720 h), indicating that HM was the main region for slow sorption. Based on the fitting results using Freundlich equation, it was found that nonlinearity of both solutes was greater in HM than in FA/HA, consistent with the sorption characteristics of individually extracted HA and HM in a separate experiment. The observed nonlinearity of the solute distribution was confirmed by using three other soil samples with organic carbon contents ranging from 0.7 to 7.9%. Distribution dynamics of PHE and PYR among various fractions were also discussed.

Adsorption↗

PubMed2005

Q2 dependence of the neutron spin structure function g2(n) at low Q2.

We present the first measurement of the Q2 dependence of the neutron spin structure function g2(n) at five kinematic points covering 0.57 (GeV/c)2 < or = Q2 < or = 1.34 (GeV/c)2 at x approximately = 0.2. Though the naive quark-parton model predicts g2 = 0, nonzero values occur in more realistic models of the nucleon which include quark-gluon correlations, finite quark masses, or orbital angular momentum. When scattering from a noninteracting quark, g2(n) can be predicted using next-to-leading order fits to world data for g1(n). Deviations from this prediction provide an opportunity to examine QCD dynamics in nucleon structure. Our results show a positive deviation from this prediction at lower Q2, indicating that contributions such as quark-gluon interactions may be important. Precision data obtained for g1(n) are consistent with next-to-leading order fits to world data.

Journal Article↗

PubMed2005

An X-ray nanodiffraction technique for structural characterization of individual nanomaterials.

An X-ray micro/nanodiffraction technique that allows structural characterization of individual nanomaterials has been developed at an insertion-device beamline of the Advanced Photon Source. Using the extremely high brightness of the third-generation synchrotron radiation source and advanced high-resolution high-energy zone-plate focusing optics, X-rays of energies from 6 to 12 keV have been focused into a spot smaller than 200 nm with a photon density gain of more than 50,000 so that significant photon flux can be intercepted by a nanoscale material to generate a measurable diffraction signal for structural characterization. This paper describes the instrumentation of the technique and discusses the application of the technique to studies of tin oxide nanobelts.

Journal Article↗

PubMed2005

Enhanced proliferation, attachment and osteopontin expression by porcine periodontal cells exposed to Emdogain.

Emdogain (EMD) is an enamel matrix derivative extracted from developing porcine teeth with demonstrated periodontal regenerative potential. EMD has been shown to influence a number of properties of periodontal ligament cells including proliferation, cell attachment and matrix synthesis. To date, the effect of EMD on the epithelial cell rests of Malassez (ERM) is unknown. In this study, periodontal ligament fibroblasts, ERM, alveolar bone cells and gingival fibroblasts were obtained from porcine periodontal ligament, alveolar bone and gingiva. This study investigated, in vitro, the effect of EMD at three concentrations on proliferation, cell attachment and expression of mRNA for two mineralised tissue-related proteins (osteopontin and bone sialoprotein). As for other periodontal cells, the ERM proliferative response was enhanced by EMD. Attachment assays revealed a highly significant increase for ERM and gingival fibroblasts after EMD treatment at all concentrations. This study has also shown that EMD stimulated expression of osteopontin mRNA by ERM and alveolar bone cells. The results from this study provide evidence that EMD enhanced cellular events related with proliferation, attachment and osteopontin mRNA expression by porcine periodontal cells, in a manner consistent with its role in periodontal regenerative therapy.

Animals↗

PubMed2005

Comparison of structural response and fatigue endurance of aircraft flap-like box structures subjected to acoustic loading.

The results of an extensive test program to characterize the behavior of typical aircraft structures under acoustic loading and to establish their fatigue endurance are presented. The structures tested were the three flap-like box-type of structures. Each structure consisted of one flat (bottom) and one curved (top) stiffener stiffened skin panel, front, and rear spars, and ribs that divided the structures into three bays. The three structures, constructed from three different materials (aircraft standard aluminum alloy, Carbon Fibre Reinforced Plastic, and a Glass Fibre Metal Laminate, i.e., GLARE) had the same size and configuration, with only minor differences due to the use of different materials. A first set of acoustic tests with excitations of intensity ranging from 140 to 160 dB were carried out to obtain detailed data on the dynamic response of the three structures. The FE analysis of the structures is also briefly described and the results compared with the experimental data. The fatigue endurance of the structures was then determined using random acoustic excitation with an overall sound pressure level of 161 dB, and details of crack propagation are reported.

Acoustics↗

PubMed2004

Identification and molecular characterization of a novel y-type Glu-Dt 1 glutenin gene of Aegilops tauschii.

A novel y-type high-molecular-weight glutenin subunit possessing a slightly faster mobility than that of subunit 1Dy12 in SDS-PAGE, designated 1Dy12.1(t) in Aegilops tauschi, was identified by one- and two-dimensional gel and capillary electrophoresis. Its coding gene at the Glu-D(t) 1 locus was amplified with allele-specific-PCR primers, and the amplified products were cloned and sequenced. The complete nucleotide sequence of 2,807 bp containing an open reading frame of 1,950 bp and 857 bp of upstream sequence was obtained. A perfectly conserved enhancer sequence and the -300 element were present at positions of 209-246 bp and 424-447 bp upstream of the ATG start codon, respectively. The deduced mature protein of 1 Dy12.1(t) subunit comprised 648 amino acid residues and had a Mr of 67,518 Da, which is slightly smaller than the 1Dy12 (68,695 Da) but larger than the 1Dy10 (67,495 Da) subunits of bread wheat, respectively, and corresponds well with their relative mobilities when separated by acid-PAGE. The deduced amino acid sequence indicated that the 1Dy12.1(t) subunit displayed a greater similarity to the 1Dy10 subunit, with only seven amino acid substitutions, suggesting that this novel gene could have positive effect on bread-making quality. A phenetic tree produced by nucleotide sequences showed that the x- and y-type subunit genes were respectively clustered together and that the Glu-D(t) 1y12.1 gene of Ae. tauschii is closely related to other y-type subunit genes from the B and D genomes of hexaploid bread wheat.

Agriculture↗

PubMed2004

Precision measurement of the neutron spin asymmetryA(n)(1) and spin-flavor decomposition in the valence quark region.

We have measured the neutron spin asymmetry A(n)(1) with high precision at three kinematics in the deep inelastic region at x=0.33, 0.47, and 0.60, and Q(2)=2.7, 3.5, and 4.8 (GeV/c)(2), respectively. Our results unambiguously show, for the first time, that A(n)(1) crosses zero around x=0.47 and becomes significantly positive at x=0.60. Combined with the world proton data, polarized quark distributions were extracted. Our results, in general, agree with relativistic constituent quark models and with perturbative quantum chromodynamics (PQCD) analyses based on the earlier data. However they deviate from PQCD predictions based on hadron helicity conservation.

Journal Article↗

PubMed2004

Induction and detection of bystander effects after combined treatment of cells with 5-bromo-2'-deoxyurine, Hoechst 33 258 and ultraviolet A light.

PURPOSE: A combined treatment of cells with 5-bromo-2'-deoxyurine (BrdU), Hoechst 33 258 and ultraviolet A (UVA) light was used to introduce chromosomal aberrations in cells for the study of bystander effects in non-labelled cells. MATERIALS AND METHODS: Mixtures of BrdU-labelled and non-labelled Chinese hamster cells (V79) in S phase were exposed to Hoechst 33 258 and/or UVA light. Metaphase cells were collected and analysed for chromosomal aberrations by Giemsa staining. BrdU immunostaining was performed to verify BrdU incorporation in the cells. RESULTS: Combined treatment with BrdU, Hoechst dye and UVA light induced reduced cell survival and increased chromosomal aberrations, whereas treatment with Hoechst 33 258 and/or UVA light had no effect on cells. Elevated frequencies of chromosomal aberrations were found in non-labelled cells mixed with BrdU-labelled cells and exposed to Hoechst dye and UVA light, suggesting the induction of bystander effects by damaged BrdU-labelled cells. These bystander clastogenic effects were also observed in non-labelled cells mixed with dying cells, indicating a contribution of dying cells in the induction of the bystander effects. CONCLUSIONS: The combined treatment with BrdU, Hoechst 33 258 and UVA light is a valid method for the study of bystander effects as it enables both induction of DNA damage and discrimination of targeted cells and bystander cells.

Animals↗

PubMed2004

Optimization of submerged culture requirements for the production of mycelial growth and exopolysaccharide by Cordyceps jiangxiensis JXPJ 0109.

AIMS: The objective of the present study was to investigate the optimal culture requirements for mycelial growth and exopolysaccharide production by Cordyceps jiangxiensis JXPJ 0109 in submerged culture. METHODS AND RESULTS: The effects of medium ingredients (i.e. carbon and nitrogen sources, and growth factor) and other culture requirements (i.e. initial pH, temperature, etc.) on the production of mycelia and exopolysaccharide were observed using a one-factor-at-a-time method. More suitable culture requirements for mycelial growth and exopolysaccharide production were proved to be maltose, glycerol, tryptone, soya bean steep powder, yeast extract, medium capacity 200 ml in a 500-ml flask, agitation rate 180 rev min(-1), seed age 4-8 days, inoculum size 2.5-7.5% (v/v), etc. The optimal temperatures and initial pHs for mycelial growth and exopolysaccharide production were at 26 degrees C and pH 5 and at 28 degrees C and pH 7, respectively, and corresponding optimal culture age were observed to be 8 and 10 days respectively. According to the primary results of the one-factor-at-a-time experiments, the optimal medium for the mycelial growth and exopolysaccharide production were obtained using an orthogonal layout method to optimize further. Herein the effects of medium ingredients on the mycelial growth of C. jiangxiensis JXPJ 0109 were in the order of yeast extract > tryptone > maltose > CaCl2 > glycerol > MgSO4 > KH2PO4 and the optimal concentration of each composition was 15 g maltose (food-grade), 10 g glycerol, 10 g tryptone, 10 g yeast extract, 1 g KH2PO4, 0.2 g MgSO4, and 0.5 g CaCl2 in 1 l of distilled water, while the order of effects of those components on exopolysaccharide production was yeast extract > maltose > tryptone > glycerol > KH2PO4 > CaCl2 > MgSO4, corresponding to the optimal concentration of medium was as follows: 20 g maltose (food-grade), 8 g glycerol, 5 g tryptone, 10 g yeast extract, 1 g KH2PO4, and 0.5 g CaCl2 in 1 l of distilled water. CONCLUSIONS: Under the optimal culture requirements, the maximum exopolysaccharide production reached 3.5 g l(-1) after 10 days of fermentation, while the maximum production of mycelial growth achieved 14.5 g l(-1) after 8 days of fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the submerged culture requirements for mycelial growth and exopolysaccharide in C. jiangxiensis, and this two-step optimization strategy in this study can be widely applied to other microbial fermentation processes.

Carbon↗

PubMed2004

Immunohistochemical localization and expression of fibromodulin in adult rat periodontium and inflamed human gingiva.

OBJECTIVE: The aim of this study was to determine the distribution and expression of fibromodulin in adult rat periodontal tissues and inflamed human gingiva. MATERIALS AND METHODS: The distribution of fibromodulin in rat molar periodontium and human gingival tissue was studied by immunohistochemistry. The expression of fibromodulin mRNA from human gingival fibroblasts, periodontal ligament fibroblasts and osteoblasts was studied by reverse transcription-polymerase chain reaction (RT-PCR). For comparative purposes, the distribution and mRNA expression of collagen types I and III, as well as the two small leucine-rich proteoglycans decorin and biglycan were also studied. RESULTS: In the adult rat periodontium, fibromodulin was distributed in the suprabasal gingival epithelium, gingival and periodontal fibroblasts as well as their surrounding extracellular matrices. Strong expression was noted in the palatal gingival tissues and the interfaces of the periodontal ligament with alveolar bone and cementum. In human gingival tissues, staining of fibromodulin was detected in the connective tissue of inflamed gingiva associated with both gingivitis and periodontitis; whereas, weak staining for this molecule was noted in healthy gingival tissues. The expression of mRNA for fibromodulin was strongest in the cultured osteoblasts. Periodontal ligament fibroblasts showed only a weak level of expression for fibromodulin mRNA. CONCLUSIONS: Fibromodulin is differentially expressed throughout the periodontium being primarily associated with collagen type I in non-mineralized sites. In addition fibromodulin showed an upregulation in inflamed gingival tissue.

Animals↗

PubMed2004

Modulating effect of serum on the stimulation of plasminogen activator inhibitor 2 production in human gingival fibroblasts by lipopolysaccharide and interleukin-1beta.

OBJECTIVE: Plasminogen activator inhibitor-2 (PAI-2) is an important counter proteolysis factor which helps protect tissues from inflammatory stress. The expression of PAI-2 can be modulated by various inflammatory stimulants and mediators. The aim of the present study was to investigate how serum factors, might modulate the effects of lipopolysaccharide (LPS) and interleukin-1beta on PAI-2 production by human gingival fibroblasts. METHODS: Human gingival fibroblasts were exposed to LPS derived from Actinobacillus actinomycetemcomitans or Escherichia coli and a commercial source of interleukin-1beta (IL-1beta). The expression of PAI-2 and its mRNA was monitored by Western blotting, RT-PCR, and Northern blotting. RESULTS: The results showed that the distribution of PAI-2 synthesised by human gingival fibroblasts (HGF) was mostly as an intracellular protein (47kDa). The presence of serum in the culture media was absolutely necessary for both the secretion of PAI-2 and for the effect of the inflammatory mediators (LPS and IL-1beta). A pattern of PAI-2 response in HGF after LPS stimulation was detected with a quick up-regulation of the PAI-2 mRNA, which was down regulated when extracellular PAI-2 (60kDa mass) levels reached plateau levels. The synthesis of PAI-2 by HGF, in terms of mRNA expression and protein synthesis, was more sensitive to stimulation with lower concentrations of LPS (10 ng/ml) than with higher LPS concentrations. CONCLUSIONS: PAI-2 is a serum dependent molecule with major cytosolic localisation in HGF. Its cellular accumulation and secretion can be modulated by bacterial LPS and IL-1beta through serum factors.

Analysis of Variance↗

PubMed2003

[Immunohistochemical localization and expression of fibromodulin in the periodontium].

OBJECTIVE: To study the distribution and expression of fibromodulin in normal periodontium, so as to understand its role in periodontal tissue homeostasis. METHODS: Five normal male Lewis rats were killed and their bilateral mandibular first molars with surrounding alveolar bones and gingival tissues were taken out. Human gingival fibroblasts, fibroblasts of periodontal ligament, and osteoblasts were cultured. Immunohistochemistry with anti-fibromodulin, anti-decorin, anti-biglycan, anti-type I collagen, and anti-type III collagen antibodies and RT-PCR were used to detect the tissue distribution and cellular localization of fibromodulin and related proteoglycans, decorin and biglycan, and type I and type III collagens. RESULTS: Fibromodulin was strongly expressed in the suprabasal gingival epithelium, periodontal ligament, alveolar bone, gingival and periodontal fibroblasts as well as their matrices. Strong expression was noted in the area close to oral gingival aspect and the interfaces of periodontal ligament-alveolar bone and periodontal-ligament-cementum. Decorin was strongly expressed in the area close to the gingival sulcus in gingival tissue. Biglycan was stained evidently in gingival epithelium. Fibromodulin, decorin and biglycan mRNAs were strongly expressed in osteoblasts. mRNAs of type I and type III collagens were strongly expressed in gingival fibroblasts. CONCLUSION: Fibromodulin may interact with other small proteoglycans to regulate the network formation of periodontal collagen fibers, and may be involved in mineralization of the alveolar bone and cementum.

Animals↗