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Biomedical subjects

Xiaoming Liu

Publications and source records attributed to Xiaoming Liu.

At least 19 recordsLinked to original sources
PubMed2026

Does Toxoplasma gondii infection have a causal impact on human psychopathology? A Mendelian randomization analysis.

Toxoplasma gondii (T. gondii) is a prevalent zoonotic parasite that has been implicated in influencing human psychiatric disorders and risk-taking behaviors. Using genome-wide association study (GWAS) data, we selected 25 and 76 single-nucleotide polymorphisms as instrumental variables for anti-T. gondii IgG seropositivity and anti-T. gondii IgG levels, respectively, and conducted two-sample Mendelian randomization (MR) analyses across 18 GWAS datasets to investigate potential causal effects on addiction, bipolar disorder, obsessive-compulsive disorder, schizophrenia, and risk-taking behavior in European populations. Contrary to previous epidemiological evidence, our MR analyses do not support a significant causal association between T. gondii infection and any of the studied psychiatric disorders or risk-taking behavior. Collectively, these results establish that any true causal effect of genetic liability to T. gondii infection is likely to be small (OR < 1.18 for schizophrenia,&#x2009;<&#x2009;1.29 for bipolar disorder) and below the effect sizes typically reported in observational seroepidemiological studies, although small or infection-phase-specific effects cannot be excluded.

Humans↗
PubMed2006

Nonresonant cascaded acousto-optic mode coupling.

Nonresonant cascaded acousto-optic mode coupling under an overall phase-matching condition is presented, where phase matching is not satisfied for each of the coupling stages but the sum of the two acoustic momenta matches the optical phase detuning between the source mode and the destination mode. As a special nonresonant cascaded case, conversion from LP(01) to LP(21) and LP(02) driven by a single acoustic frequency is predicted theoretically and demonstrated experimentally.

Journal Article↗
PubMed2006

Bioelectric properties of chloride channels in human, pig, ferret, and mouse airway epithelia.

The development of effective therapies for cystic fibrosis (CF) requires animal models that can appropriately reproduce the human disease phenotype. CF mouse models have demonstrated cAMP-inducible, non-CF transmembrane conductance regulator (non-CFTR) chloride transport in conducting airway epithelia, and this property is thought to be responsible for the lack of a spontaneous CF-like phenotype in the lung. Thus, an understanding of species diversity in airway epithelial electrolyte transport and CFTR function is critical to developing better models for CF. Two species currently being used in attempts to develop better animal models of CF include the pig and ferret. In the study reported here, we sought to comparatively characterize the bioelectric properties of in vitro polarized airway epithelia--from human, mouse, pig and ferret--grown at the air-liquid interface (ALI). Bioelectric properties analyzed include amiloride-sensitive Na(+) transport, 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS)-sensitive Cl(-) transport, and cAMP-sensitive Cl(-) transport. In addition, as an index for CFTR functional conservation, we evaluated the ability of four CFTR inhibitors, including glibenclamide, 5-nitro-2-(3-phenylpropyl-amino)-benzoic acid, CFTR (inh)-172, and CFTR(inh)-GlyH101, to block cAMP-mediated Cl(-) transport. Compared with human epithelia, pig epithelia demonstrated enhanced amiloride-sensitive Na(+) transport. In contrast, ferret epithelia exhibited significantly reduced DIDS-sensitive Cl(-) transport. Interestingly, although the four CFTR inhibitors effectively blocked cAMP-mediated Cl(-) secretion in human airway epithelia, each species tested demonstrated unique differences in its responsiveness to these inhibitors. These findings suggest the existence of substantial species-specific differences at the level of the biology of airway epithelial electrolyte transport, and potentially also in terms of CFTR structure/function.

Amino Acid Sequence↗
PubMed2006

Evidence for recombination in Mycobacterium tuberculosis.

Due to its mostly isolated living environment, Mycobacterium tuberculosis is generally believed to be highly clonal, and thus recombination between different strains must be rare and is not critical for the survival of the species. To investigate the roles recombination could have possibly played in the evolution of M. tuberculosis, an analysis was conducted on previously determined genotypes of 36 synonymous single nucleotide polymorphisms (SNPs) in 3,320 M. tuberculosis isolates. The results confirmed the predominant clonal structure of the M. tuberculosis population. However, recombination between different strains was also suggested. To further resolve the issue, 175 intergenic SNPs and 234 synonymous SNPs were genotyped in 37 selected representative strains. A clear mosaic polymorphic pattern ahead of the MT0105 locus encoding a PPE (Pro-Pro-Glu) protein was obtained, which is most likely a result of recombination hot spot. Given that PPE proteins are thought to be critical in host-pathogen interactions, we hypothesize that recombination has been influential in the history of M. tuberculosis and possibly a major contributor to the diversity observed ahead of the MT0105 locus.

Antigens, Bacterial↗
PubMed2006

Catalytic polymerization and facile grafting of poly(furfuryl alcohol) to single-wall carbon nanotube: preparation of nanocomposite carbon.

A nanocomposite carbon was prepared by grafting a carbonizable polymer, poly(furfuryl alcohol) (PFA), to a single-wall carbon nanotube (SWNT). The SWNT was first functionalized with arylsulfonic acid groups on the sidewall via a method using a diazonium reagent. Both Raman and FTIR spectroscopies were used to identify the functional groups on the nanotube surface. HRTEM imaging shows that the SWNT bundles are exfoliated after functionalization. Once this state of the SWNTs was accomplished, the PFA-functionalized SWNT (PFA-SWNT) was prepared by in situ polymerization of furfuryl alcohol (FA). The sulfonic acid groups on the surface of the SWNT acted as a catalyst for FA polymerization, and the resulting PFA then grafted to the SWNTs. The surfaces of the SWNTs converted from hydrophilic to hydrophobic when they were wrapped with PFA. The formation of the polymer and the attraction between it and the sulfonic acid groups were confirmed by IR spectra. A nanocomposite carbon was generated by heating the PFA-SWNT in argon at 600 degrees C, a process during which the PFA was transformed to nanoporous carbon (NPC) and the sulfonic acid groups were cleaved from the SWNT. Based upon the Raman spectra and HRTEM images of the composite, it is concluded that SWNTs survive this process and a continuous phase is formed between the NPC and the SWNT.

Journal Article↗
PubMed2006

Unique biologic properties of recombinant AAV1 transduction in polarized human airway epithelia.

The choice of adeno-associated virus serotypes for clinical applications is influenced by the animal model and model system used to evaluate various serotypes. In the present study, we sought to compare the biologic properties of rAAV2/1, rAAV2/2, and rAAV2/5 transduction in polarized human airway epithelia using viruses purified by a newly developed common column chromatography method. Results demonstrated that apical transduction of human airway epithelia with rAAV2/1 was 100-fold more efficient than rAAV2/2 and rAAV2/5. This transduction profile in human airway epithelia (rAAV2/1 >> rAAV2/2 = rAAV2/5) was significantly different from that seen following nasal administration of these vectors to mouse lung (rAAV2/5 > rAAV2/1 >> rAAV2/2), emphasizing differences in transduction of these serotypes between these two species. In stark contrast to rAAV2/2 and rAAV2/5, rAAV2/1 transduced both the apical and basolateral membrane of human airway epithelia with similar efficiency. However, the overall level of transduction across serotypes did not correlate with vector internalization. We hypothesized that differences in post-entry processing of these serotypes might influence the efficiency of apical transduction. To this end, we tested the effectiveness of proteasome inhibitors to augment nuclear translocation and gene expression from the three serotypes. Augmentation of rAAV2/1 apical transduction of human polarized airway epithelia was 10-fold lower than that for rAAV2/2 and rAAV2/5. Cellular fractionation studies demonstrated that proteasome inhibitors more significantly enhanced rAAV2/2 and rAAV2/5 translocation to the nucleus than rAAV2/1. These results demonstrate that AAV1 transduction biology in human airway epithelia differs from that of AAV2 and AAV5 by virtue of altered ubiquitin/proteasome sensitivities that influence nuclear translocation.

Animals↗
PubMed2006

Ultraviolet wave plates based on monolithic integration of two fully filled and planarized nanograting layers.

We successfully fabricated a high-performance half-wave plate for the 405 nm wavelength based on monolithic integration of two nanograting layers. Each of the nanograting layers functions as a quarter-wave plate. Both of the nanograting layers were fully filled and planarized to achieve the monolithic integration. UV-nanoimprint lithography, along with thin-film deposition, high-aspect-ratio reactive ion etching, and trench-filling technologies, was used in fabrication and integration of the individual nanograting layers. High-aspect-ratio nanogratings with sub-50 nm linewidths and 100 nm spacing were fabricated to achieve good optical performance at the near-UV wavelength. The ability to integrate multiple nanostructure-based optical layers opens a path for integrated multifunction devices, as well as a new strategy for driving both miniaturization and cost.

Journal Article↗
PubMed2006

Tunable photoluminescent and cathodoluminescent properties of ZnO and ZnO:Zn phosphors.

ZnO and ZnO:Zn powder phosphors were prepared by the polyol-method followed by annealing in air and reducing gas, respectively. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectra (XPS), electron paramagnetic resonance (EPR), and photoluminescence (PL) and cathodoluminescence (CL) spectra, respectively. The results indicate that all samples are in agreement with the hexagonal structure of the ZnO phase and the particle sizes are in the range of 1-2 microm. The PL and CL spectra of ZnO powders annealed at 950 degrees C in air consist of a weak ultraviolet emission band (approximately 390 nm) and a broad emission band centered at about 527 nm, exhibiting yellow emission color to the naked eyes. When the sample was reduced at the temperatures from 500 to 1050 degrees C, the yellow emission decreased gradually and disappeared completely at 800 degrees C, whereas the ultraviolet emission band became the strongest. Above this temperature, the green emission ( approximately 500 nm) appeared and increased with increasing of reducing temperatures. According to the EPR results and spectral analysis, the yellow and green emissions may arise from the transitions of photogenerated electron close to the conduction band to the deeply trapped hole in the single negatively charged interstitial oxygen ion (Oi(-)) and the single ionized oxygen vacancy (V.O) centers, respectively.

Journal Article↗
PubMed2006

Effects of hydroxyethyl starch 130/0.4 on pulmonary capillary leakage and cytokines production and NF-kappaB activation in CLP-induced sepsis in rats.

BACKGROUND: Sepsis and resulting multiple system organ failure are the leading causes of mortality in intensive care units. Hydroxyethyl starch (HES) 130/0.4 was a novel preparation, developed to improve the pharmacokinetics of current medium molecular weight HES solutions. This study was designed to explore the effects of HES 130/0.4 on pulmonary capillary permeability (PCP), production of cytokines, and activation of transcription factor in septic rats induced by cecal ligation and puncture (CLP). MATERIALS AND METHODS: Adult male Sprague Dawley rats were randomly divided into six groups (six rats/group): saline controls (30 ml/kg); CLP plus saline (30 ml/kg); CLP plus HES (7.5, 15, or 30 ml/kg, respectively), and HES alone (30 ml/kg). Mean arterial blood pressure and heart rate were monitored during the experiment process. Myeloperoxidase (MPO) activity, wet/dry weight ratio, PCP, tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, IL-10, and nuclear factor-kappa B (NF-kappaB) were investigated at 6 h. RESULTS: We demonstrated that CLP could provoke significant injury in lung, characterized by increase in PCP, wet/dry weight ratio, MPO activity, TNF-alpha, IL-6, and IL-10 level, and NF-kappaB activation. Without obvious influence on systemic macro-hemodynamics, HES 15 ml/kg and 30 ml/kg significantly reduced CLP-induced elevation of pulmonary capillary permeability, wet/dry weight ratio, and production of IL-6. Meanwhile, HES 15 ml/kg increased IL-10 level and HES 7.5, 15, and 30 ml/kg suppressed MPO activity, TNF-alpha level, and NF-kappaB activation. CONCLUSION: HES 130/0.4 can inhibit CLP-induced PCP by attenuating pulmonary inflammation and NF-kappaB activation in vivo.

Animals↗
PubMed2006

Cloned ferrets produced by somatic cell nuclear transfer.

Somatic cell nuclear transfer (SCNT) offers great potential for developing better animal models of human disease. The domestic ferret (Mustela putorius furo) is an ideal animal model for influenza infections and potentially other human respiratory diseases such as cystic fibrosis, where mouse models have failed to reproduce the human disease phenotype. Here, we report the successful production of live cloned, reproductively competent, ferrets using species-specific SCNT methodologies. Critical to developing a successful SCNT protocol for the ferret was the finding that hormonal treatment, normally used for superovulation, adversely affected the developmental potential of recipient oocytes. The onset of Oct4 expression was delayed and incomplete in parthenogenetically activated oocytes collected from hormone-treated females relative to oocytes collected from females naturally mated with vasectomized males. Stimulation induced by mating and in vitro oocyte maturation produced the optimal oocyte recipient for SCNT. Although nuclear injection and cell fusion produced mid-term fetuses at equivalent rates (approximately 3-4%), only cell fusion gave rise to healthy surviving clones. Single cell fusion rates and the efficiency of SCNT were also enhanced by placing two somatic cells into the perivitelline space. These species-specific modifications facilitated the birth of live, healthy, and fertile cloned ferrets. The development of microsatellite genotyping for domestic ferrets confirmed that ferret clones were genetically derived from their respective somatic cells and unrelated to their surrogate mother. With this technology, it is now feasible to begin generating genetically defined ferrets for studying transmissible and inherited human lung diseases. Cloning of the domestic ferret may also aid in recovery and conservation of the endangered black-footed ferret and European mink.

Animals↗
PubMed2006

Stem cells in the lung.

The lung is composed of two major anatomically distinct regions-the conducting airways and gas-exchanging airspaces. From a cell biology standpoint, the conducting airways can be further divided into two major compartments, the tracheobronchial and bronchiolar airways, while the alveolar regions of the lung make up the gas-exchanging airspaces. Each of these regions consists of distinct epithelial cell types with unique cellular physiologies and stem cell compartments. This chapter focuses on model systems with which to study stem cells in the adult tracheobronchial airways, also referred to as the proximal airway of the lung. Important in such models is an appreciation for the diversity of stem cell niches in the conducting airways that provide localized environmental signals to both maintain and mobilize stem cells in the setting of airway injury and normal cellular turnover. Because cellular turnover in airways is relatively slow, methods for analysis of stem cells in vivo have required prior injury to the lung. In contrast, ex vivo and in vitro models for analysis of airway stem cells have used genetic markers to track lineage relationships together with reconstitution systems that mimic airway biology. Over the past decades, several widely acceptable methods have been developed and used in the characterization of adult airway stem/progenitor cells. These include localization of label-retaining cells (LRCs), retroviral tagging of epithelial cells seeded into xenografts, air-liquid interface cultures to track clonal proliferative potential, and multiple transgenic mouse models. This chapter reviews the biologic context and use of these models while providing detailed methods for several of the more broadly useful models for studying adult airway stem/progenitor cell types.

Adult Stem Cells↗
PubMed2006

Large area, 38 nm half-pitch grating fabrication by using atomic spacer lithography from aluminum wire grids.

We wrapped 150 nm period aluminum wire grid polarizer (WGP) with AlSiOx by using atomic layer deposition at 250 degrees C. The nanometer precision coating defined the spacer to double the spatial frequency of the 100 mm diameter grating fabricated by using a legacy immersion holography setup at 351 nm wavelength. Half-pitch grating of approximately 38 nm was demonstrated with good pattern uniformity, excellent repeatability, and a wide processing window. We believe 10 nm half-pitch grating over even larger areas are viable, overcoming one major hurdle to commercialize nanoimprint.

Journal Article↗
PubMed2006

Genotyping of Sporothrix schenckii by analysis of ribosomal DNA regions.

An attempt was made to identify the genotypes of 31 Sporothrix schenckii strains and the relationship between the genotypes, the geographic distributions and clinical manifestations using restriction fragment length polymorphic analysis. The total DNA was extracted by cetyltrimethyl ammonium bromide. The polymorphisms were detected by hybridisation of ApaI-digested Sporothrix genomic DNA with a probe amplified from the small subunit ribosomal DNA and adjacent internal transcribed spacer regions. The band patterns manifested by Southern blotting were explored to investigate the genotypes of the 31 strains of S. schenckii collected from five different areas in China. Of the data from the 31 strains of S. schenckii studied, 15 individual patterns (DNA type A-O) were recognised. Type A-C accounted for 51.61% of all the strains. The DNA typing of S. schenckii by Southern blotting was highly sensitive and highly distinguishable. We also found a significant correlation between DNA patterns and different geographic areas and clinical manifestations.

Blotting, Southern↗
PubMed2006

Direct determination of tellurium in geological samples by inductively coupled plasma mass spectrometry using ethanol as a matrix modifier.

Direct determination of tellurium in geological samples by inductively coupled plasma mass spectrometry (ICP-MS) is often complicated by its low abundance, poor analytical sensitivity, and the presence of xenon interferences. Therefore, a simplified and rapid method for direct determination of nanogram levels of tellurium in geological samples using ICP-MS by reduction of interferences and improvement of sensitivity was developed. It is impossible to resolve 126Te and 128Te from isotope interferences of Xe even by currently available high-resolution magnetic mass spectrometry due to the extremely small mass difference (0.001-0.002 amu). However, the addition of 4% ethanol was found to suppress the interferences of Xe by a factor of 6 and increases the sensitivity of Te determination in ICP-MS by a factor of 3 relative to the values obtained in conventional 3% (v/v) HNO3 solution at the corresponding optimum operating conditions, respectively. The detection limits of 126Te and 128Te were reduced by a factor of 7.2 and 8.8, respectively, and the limit of quantitation (LOQ) for 126Te in the presence of 4% ethanol was 1.5 ng g(-1) (the LOQ is expressed as the concentration in the solid samples, thereby taking into account the dilution factor of 1000). The agreement between the determined Te concentration values (r = 0.998) in various geological samples (n = 140) by using isotopes of 126Te and 128Te indicates negligible contributions of polyatomic interferences produced by the addition of ethanol at these m/z. The proposed method was successfully applied to the direct determination of nanogram levels of Te in a series of international geological reference materials.

Journal Article↗
PubMed2006

Recombinant human erythropoietin (rhEPO) preconditioning on nuclear factor-kappa B (NF-kB) activation & proinflammatory cytokines induced by myocardial ischaemia-reperfusion.

BACKGROUND & OBJECTIVES: Erythropoietin (EPO), originally identified for its critical hormonal role in promoting erythrocyte survival and differentiation, has shown to a protective effect in myocardial ischaemia-reperfusion (I-R) injury in animal model. However, the precise mechanisms remain unclear. The objective of this study was to determine the roles of nuclear factor-kappa B (NF-kB) and associated cytokines induced by I-R in the cardioprotection by recombinant human erythropoietin (rhEPO). Morphopathological observations were also made on the ultrastructure of myocardial tissue. METHODS: Myocardial I-R rat model was established by 30 min ligation of left descending coronary and 3 h reperfusion. RhEPO or saline solution was intraperitoneally injected 24 h before I-R insult. The infarct sizes were measured by triphenyltetrazolium chloride (TTC)-Evans blue technique and ultrastructural organizations were observed by a transmission electron microscope. Tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-10 concentrations were analyzed by enzyme-linked immunosorbance assays and NF-kB by electrophoretic mobility shift assay. TNF-alpha and IL-6 mRNA expression were studied by the reverse-transcription polymerase chain reaction (RT-PCR). RESULTS: A single bolus injection of 5,000 units/kg of rhEPO 24 h before insult remarkably reduced infarct size and improved ultrastructural organization of I-R myocardium. It greatly suppressed TNF-alpha and IL-6 expression, but enhanced IL-10 production. It modestly activated NF-kB before I-R insult and markedly attenuated subsequent NF-kB activation during sustained I-R. INTERPRETATION & CONCLUSION: The suppression of proinflammatory cytokines expression may act by inhibiting NF-kB activation during I-R, but not by induction of IL-10. This might be one of the molecular mechanisms of rhEPO in cardioprotection. In addition, NF-kB was suggested to play a dual role in cardioprotective effects of rhEPO.

Analysis of Variance↗