Biomedical subjects

J Wang

Publications and source records attributed to J Wang.

At least 109 records · Page 6Linked to original sources

PubMed2006

Production of interferon-gamma by microglia.

Neural cells do not usually interact with immune cells because of the lack of major histocompatibility complex (MHC) antigen expression. Interferon-gamma (IFN-gamma) enables this interaction via induction of MHC antigen expression in neural cells. Thus, IFN-gamma is a critical cytokine for the development of central nervous system (CNS) pathologies. IFN-gamma, however, is considered to be produced exclusively by lymphoid cells. Here, we show for the first time that murine microglia produce IFN-gamma in response to IL-12 and/or IL-18, using RT-PCR detection of IFN-gamma mRNA and Western blotting and immunohistochemical analysis for cytoplasmic expression of IFN-gamma. Stimulation of microglia with IL-12 and IL-18 resulted in MHC class II mRNA expression in microglia. Since IL-12 and IL-18 are produced in the CNS by glial cells, these cytokines may play a critical role in the initiation of neural-immune cell interaction and the induction of autoimmune processes in the CNS via induction of IFN-gamma and MHC antigens.

Animals↗

PubMed2006

Human saliva proteome and transcriptome.

This paper tests the hypothesis that salivary proteins and their counterpart mRNAs co-exist in human whole saliva. Global profiling of human saliva proteomes and transcriptomes by mass spectrometry (MS) and expression microarray technologies, respectively, revealed many similarities between saliva proteins and mRNAs. Of the function-known proteins identified in saliva, from 61 to 70% were also found present as mRNA transcripts. For genes not detected at both protein and mRNA levels, we made further efforts to determine if the counterpart is present. Of 19 selected genes detected only at the protein level, the mRNAs of 13 (68%) genes were found in saliva by RT-PCR. In contrast, of many mRNAs detected only by microarrays, their protein products were found in saliva, as reported previously by other investigators. The saliva transcriptome may provide preliminary insights into the boundary of the saliva proteome.

Adult↗

PubMed2006

Lifetime performance in foraging honeybees: behaviour and physiology.

Honeybees, Apis mellifera, gradually increase their rate of forage uptake as they gain foraging experience. This increase in foraging performance has been proposed to occur as a result of learning; however, factors affecting flight ability such as changes in physiological components of flight metabolism could also contribute to this pattern. Thus, the purpose of this study was to assess the contribution of physiological changes to the increase in honeybee foraging performance. We investigated aspects of honeybee flight muscle biochemistry throughout the adult life, from non-foraging hive bees, through young and mature foragers, to old foragers near the end of their lifespan. Two-dimensional gel proteomic analysis on honeybee thorax muscle revealed an increase in several proteins from hive bees to mature foragers including troponin T 10a, aldolase and superoxide dismutase. By contrast, the activities (V(max)) of enzymes involved in aerobic performance, phosphofructokinase, hexokinase, pyruvate kinase and cytochrome c oxidase, did not increase in the flight muscles of hive bees, young foragers, mature foragers and old foragers. However, citrate synthase activity was found to increase with foraging experience. Hence, our results suggest plasticity in both structural and metabolic components of flight muscles with foraging experience.

Age Factors↗

PubMed2005

Afferent connections of the subparafascicular area in rat.

The subparafascicular nucleus and the subparafascicular area are the major sites of synthesis of the recently discovered neuropeptide, tuberoinfundibular peptide of 39 residues (TIP39). Better knowledge of the neuronal inputs to the subparafascicular area and nucleus will facilitate investigation of the functions of TIP39. Thus, we have injected the retrograde tracer cholera toxin B subunit into the rostral, middle, and caudal parts of the rat subparafascicular nucleus. We report that the afferent projections to the subparafascicular nucleus and area include the medial prefrontal, insular, and ectorhinal cortex, the subiculum, the lateral septum, the anterior amygdaloid area, the medial amygdaloid nucleus, the caudal paralaminar area of the thalamus, the lateral preoptic area, the anterior, ventromedial, and posterior hypothalamic nuclei, the dorsal premamillary nucleus, the zona incerta and Forel's fields, the periaqueductal gray, the deep layers of the superior colliculus, cortical layers of the inferior colliculus, the cuneiform nucleus, the medial paralemniscal nucleus, and the parabrachial nuclei. Most of these regions project to all parts of the subparafascicular nucleus. However, the magnocellular subparafascicular neurons, which occupy the middle part of the subparafascicular nucleus, may not receive projections from the medial prefrontal and insular cortex, the medial amygdaloid nucleus, the lateral preoptic area, and the parabrachial nuclei. In addition, double labeling of cholera toxin B subunit and TIP39 revealed a remarkable similarity between input regions of the subparafascicular area and the brain TIP39 system. Neurons within regions that contain TIP39 cell bodies as well as regions that contain TIP39 fibers project to the subparafascicular area. Overall, the afferent connections of the subparafascicular nucleus and area suggest its involvement in central reproductive, visceral, nociceptive, and auditory regulation.

Afferent Pathways↗

PubMed2005

Regulation of SDF-1 (CXCL12) production by osteoblasts; a possible mechanism for stem cell homing.

Stromal derived factor-1 (SDF-1 or CXCL12) controls many aspects of stem cell function including trafficking and proliferation. Previously, it was demonstrated that DNA-damaging agents such as irradiation, cyclophosphamide or 5-fluorouracil increase the expression of SDF-1 by osteoblasts in murine marrow. Here, the production of SDF-1 by osteoblasts in vitro in response to cytokines known to be particularly important in bone physiology was examined using primary human osteoblasts (HOBs), mixed marrow stromal cells (BMSCs), and by, mouse, rat and human osteoblast-like cell lines. From these studies, it was determined that the expression of SDF-1 is an early feature of osteoblastic induction that may be modulated by IL-1beta, PDGF-BB, VEGF, TNF-alpha and PTH. Each of these factors increased SDF-1 synthesis, while TGF-beta1 decreased SDF-1 secretion. Of note, the biodistribution of SDF-1 in culture was equally distributed between the medium and detergent-soluble and -insoluble fractions of the cultures. Immunohistochemistry of developing bones demonstrated that SDF-1 was also a feature of early bone development first beginning in the perichondrium and moving into the marrow cavity of the developing bone analogue. As SDF-1 expression increases in response to PTH in vitro, animals were treated with an anabolic regime of PTH for 21 days. Under these conditions, significant increases in SDF-1 mRNA expression were observed near the growth plate and epiphysis regions of the long bones. Yet, in serum, immunodetectable SDF-1 levels were significantly reduced (24%) in the PTH-treated animals (Vehicle: 408 +/- 25 vs. PTH 308 +/- 20 SDF-1 pg/ml). Together, these data suggest a possible mechanism for localizing stem cells into a developing marrow where increased expression of SDF-1 in the local marrow environment along with decreased SDF-1 in the serum may create a homing gradient.

Cell Proliferation↗

PubMed2005

Adsorption dynamics of CO2 on copper-precovered ZnO(0001)-Zn: a molecular-beam scattering and thermal-desorption spectroscopy study.

Initial, S(0), as well as coverage-dependent adsorption probability measurements, S(Theta), have been conducted at normal impact angle and as a function of the impact energy of CO(2), E(i), adsorption temperature, T(s), and copper precoverage, Theta(Cu) (at 300 K). S(0), which decreased from approximately 0.4 exponentially to approximately 0.05 with E(i) was independent of Theta(Cu). Astonishingly, S(0) for Cu on ZnO(0001)-Zn is smaller than for the clean support which indicates a chemical modification of the support by the Cu deposits. S(Theta) curves consist of two regimes, a Kisliuk-type and Langmuirian-type section. The first is consistent with capture zone models; the second may indicate direct adsorption of CO(2) on the Cu cluster. The thermal-desorption (TDS) curves for Cu on ZnO(0001)-Zn consist of two structures with binding energies of 26 and approximately 40 kJmol (nu=1 x 10(13) ls). The TDS results indicate that CO(2) populates predominantly the Cu deposits and the rim along the Cu nanoparticles. No indications for CO(2) dissociation could be obtained with Auger electron spectroscopy.

Journal Article↗

PubMed2005

Isobaric and isochoric fragilities and the influence of volume on the temperature dependence of local segmental relaxation in polyvinylethylene networks.

The ratio of the isochoric and isobaric activation enthalpies at T(g) is used to quantify the relative contributions of the specific volume and temperature to the local segmental dynamics of polyvinylethylene networks. The dynamics of the networks become more dominated by temperature with increasing cross-link density, consistent with an increasing isobaric fragility. We also find a correlation between the isochoric and isobaric fragilities for the polyvinylethylene networks, in accord with a previously reported relationship between these two quantities for polymers and molecular glass-forming liquids [R. Casalini and C. M. Roland, Phys. Rev. E 72, 031503 (2005)].

Journal Article↗

PubMed2005

Enhancement of the Gibberella zeae growth inhibitory lipopeptides from a Bacillus subtilis mutant by ion beam implantation.

Bacillus subtilis JA antagonized the growth of Gibberella zeae. In order to reduce growth of this fungi pathogen to a greater extent, low-energy ion beam implantation was applied in mutant breeding. We studied the effects of different energies and different doses of nitrogen ion implantation. The mutant strain designated as JA026 was obtained showing higher inhibition activity in the screening plate. Its inhibition zone against indicator organism increased by 14.3% compared to the original strain. The electrospray ionization mass spectrometry (ESI/MS) analysis indicated that the antifungal lipopeptides produced by the mutant were identical to those produced by the wild-type strain. The mutant strain exhibited favorable properties including the high yield of antifungal lipopeptides production and faster growth over the parent strain, which suggested that this strain would be a promising biocontrol candidate in agriculture.

Antifungal Agents↗

PubMed2005

Adsorption of CO on the copper-precovered ZnO(0001) surface: a molecular-beam scattering study.

Auger electron spectroscopy (AES), thermal-desorption spectroscopy (TDS), and, in particular, molecular-beam scattering techniques have been combined to address particle size effects in the adsorption of CO on Cu-on-ZnO(0001). AES and TDS lead to a Cu coverage, theta(Cu), calibration. The TDS curves, as a function of theta(Cu) and CO exposure, revealed three structures at 150, 220, and 260-280 K, in agreement with prior studies. However, a unique assignment of the TDS structures to a particular Cu face was not possible. An enhancement of the initial adsorption probability, S0, with respect to the support indicates the effect of the Cu nanoparticles. Despite that the shape of S0 versus impact energy curves was independent of theta(Cu) and agreed with Cu single-crystal reference systems, distinct particle size effects were present with regard to the adsorption mechanism. It was possible to observe a crossover from Langmuir-type adsorption dynamics to more precursor-assisted adsorption dynamics with increasing theta(Cu). Thus, a dynamic structure-activity relationship was evident, i.e., the energy-transfer mechanism depends on the Cu morphology.

Journal Article↗

PubMed2005

Self-regulating gene: an exact solution.

An exact steady-state solution of the stochastic equations governing the behavior of a gene regulated by a self-generated proteomic atmosphere is presented. The solutions depend on an adiabaticity parameter measuring the relative rate of DNA-protein unbinding and protein degradation. The steady-state solution reveals deviations from the commonly used Ackers et al approximation based on the equilibrium law of mass action, allowing anticooperative behavior in the "nonadiabatic" limit of slow binding and unbinding rates. Noise from binding and unbinding events dominates the shot noise of protein synthesis and degradation up to quite high values of the adiabaticity parameter.

Animals↗

PubMed2005

Calculation and usage of containment monitor radiation readings during PWR accidents.

A computer code named CALCON for calculation of containment monitor radiation readings is introduced. The validity of the code was verified by comparison with data given in IAEA technical documents. The contribution of isotopes to containment readings under conditions of core melt, gap release and normal coolant release were investigated. The conclusions were that the radiation reading in containment is mainly from iodine and noble gases when sprays are off, and the radiation reading is mainly from noble gases when sprays are on, and during the beginning hours when radionuclides are released into containment, the monitor readings will decrease rapidly. Curves of containment radiation readings versus shutdown time for DAYA BAY nuclear power plant were calculated using CALCON.

Radiation Dosage↗

PubMed2005

Studies on LXR- and FXR-mediated effects on cholesterol homeostasis in normal and cholic acid-depleted mice.

As previously reported by us, mice with targeted disruption of the CYP8B1 gene (CYP8B1-/-) fail to produce cholic acid (CA), upregulate their bile acid synthesis, reduce the absorption of dietary cholesterol and, after cholesterol feeding, accumulate less liver cholesterol than wild-type (CYP8B1+/+) mice. In the present study, cholesterol-enriched diet (0.5%) or administration of a synthetic liver X receptor (LXR) agonist strongly upregulated CYP7A1 expression in CYP8B1-/- mice, compared to CYP8B1+/+ mice. Cholesterol-fed CYP8B1-/- mice also showed a significant rise in HDL cholesterol and increased levels of liver ABCA1 mRNA. A combined CA (0.25%)/cholesterol (0.5%) diet enhanced absorption of intestinal cholesterol in both groups of mice, increased their liver cholesterol content, and reduced their expression of CYP7A1 mRNA. The ABCG5/G8 liver mRNA was increased in both groups of mice, but cholesterol crystals were only observed in bile from the CYP8B1+/+ mice. The results demonstrate the cholesterol-sparing effects of CA: enhanced absorption and reduced conversion into bile acids. Farnesoid X receptor (FXR)-mediated suppression of CYP7A1 in mice seems to be a predominant mechanism for regulation of bile acid synthesis under normal conditions and, as confirmed, able to override LXR-mediated mechanisms. Interaction between FXR- and LXR-mediated stimuli might also regulate expression of liver ABCG5/G8.

ATP Binding Cassette Transporter 1↗

PubMed2005

Segment-specific resistivity improves body fluid volume estimates from bioimpedance spectroscopy in hemodialysis patients.

Discrepancies in body fluid estimates between segmental bioimpedance spectroscopy (SBIS) and gold-standard methods may be due to the use of a uniform value of tissue resistivity to compute extracellular fluid volume (ECV) and intracellular fluid volume (ICV). Discrepancies may also arise from the exclusion of fluid volumes of hands, feet, neck, and head from measurements due to electrode positions. The aim of this study was to define the specific resistivity of various body segments and to use those values for computation of ECV and ICV along with a correction for unmeasured fluid volumes. Twenty-nine maintenance hemodialysis patients (16 men) underwent body composition analysis including whole body MRI, whole body potassium (40K) content, deuterium, and sodium bromide dilution, and segmental and wrist-to-ankle bioimpedance spectroscopy, all performed on the same day before a hemodialysis. Segment-specific resistivity was determined from segmental fat-free mass (FFM; by MRI), hydration status of FFM (by deuterium and sodium bromide), tissue resistance (by SBIS), and segment length. Segmental FFM was higher and extracellular hydration of FFM was lower in men compared with women. Segment-specific resistivity values for arm, trunk, and leg all differed from the uniform resistivity used in traditional SBIS algorithms. Estimates for whole body ECV, ICV, and total body water from SBIS using segmental instead of uniform resistivity values and after adjustment for unmeasured fluid volumes of the body did not differ significantly from gold-standard measures. The uniform tissue resistivity values used in traditional SBIS algorithms result in underestimation of ECV, ICV, and total body water. Use of segmental resistivity values combined with adjustment for body volumes that are neglected by traditional SBIS technique significantly improves estimations of body fluid volume in hemodialysis patients.

Algorithms↗

PubMed2005

Ultrafast quenching of ferromagnetism in InMnAs induced by intense laser irradiation.

Time-resolved magneto-optical Kerr spectroscopy of ferromagnetic InMnAs reveals two distinct demagnetization processes--fast (<1 ps) and slow (approximately 100 ps). Both components diminish with increasing temperature and are absent above the Curie temperature. The fast component rapidly grows with pump power and saturates at high fluences (>10 mJ/cm(2)); the saturation value indicates a complete quenching of ferromagnetism on a subpicosecond time scale. We attribute this fast dynamics to spin heating through p-d exchange interaction between photocarriers and Mn ions, while the approximately 100 ps component is interpreted as spin-lattice relaxation.

Journal Article↗

PubMed2005

Understanding the spatial diffusion process of severe acute respiratory syndrome in Beijing.

OBJECTIVES: To measure the spatial contagion of severe acute respiratory syndrome (SARS) in Beijing and to test the different epidemic factors of the spread of SARS in different periods. METHODS: A join-count spatial statistic study was conducted and the given hypothetical processes of the spread of SARS in Beijing were tested using various definitions of 'joins'. RESULTS: The spatial statistics showed that of the six diffusion processes, the highest negative autocorrelation occurred in the doctor-number model (M-5) and the lowest negative autocorrelation was found in the population-amount model (M-3). The results also showed that in the whole 29-day research period, about hour or more days experienced a significant degree of contagion. CONCLUSIONS: Spatial analysis is helpful in understanding the spatial diffusion process of an epidemic. The geographical relationships were important during the early phase of the SARS epidemic in Beijing. The statistic based on the number of doctors was significant and more informative than that of the number of hospitals. It reveals that doctors were important in the spread of SARS in Beijing, and hospitals were not as important as doctors in the contagion period. People are the key to the spread of SARS, but the population density was more significant than the population size, although they were both important throughout the whole period.

China↗

PubMed2005

Observation of the decay xi0 --> sigma+ mu- nu(mu).

The xi0 muon semileptonic decay has been observed for the first time with nine identified events using the KTeV beam line and detector at Fermilab. The decay is normalized to the xi0 beta decay mode and yields a value for the ratio of decay rates gamma(xi0 --> sigma+ mu- nu(mu))/gamma(xi0 --> sigma+ e- nu(e)) of [1.8(-0.5)(+0.7)(stat) +/- 0.2(syst)] x 10(-2). This is in agreement with the SU(3) flavor symmetric quark model.

Journal Article↗

PubMed2005

Characterization and control of plasma density distribution for the development of solid-target x-ray lasers.

By using deflectometry of a longitudinal probe pulse and reflective interferometry of a transverse probe pulse to resolve the spatiotemporal distribution of the preformed plasma, we characterize and control the plasma density distribution near the target surface for the development of solid-target x-ray lasers. We show that the use of prepulses in an ignitor-heater scheme can increase the scale length of the preformed plasma and how the effect varies with target materials. Many important issues crucial to x-ray lasing such as electron density distribution, electron temperature, and the optimal timing between pumping pulses can be resolved with these methods.

Journal Article↗

PubMed2005

Melting temperature of ice Ih calculated from coexisting solid-liquid phases.

We carried out molecular-dynamics simulations by using the two-phase coexistence method with the constant pressure, particle number, and enthalpy ensemble to compute the melting temperature of proton-disordered hexagonal ice I(h) at 1-bar pressure. Four models of water were considered, including the widely used TIP4P [W. L. Jorgensen, J. Chandrasekha, J. D. Madura, R. W. Impey, and M. L. Klein, J. Chem. Phys.79, 926 (1983)] and TIP5P [M. W. Mahoney and W. L. Jorgensen J. Chem. Phys.112, 8910 (2000)] models, as well as recently improved TIP4P and TIP5P models for use with Ewald techniques-the TIP4P-Ew [W. Horn, W. C. Swope, J. W. Pitera, J. C. Madura, T. J. Dick, G. L. Hura, and T. Head-Gordon, J. Chem. Phys.120, 9665 (2004)] and TIP5P-Ew [S. W. Rick, J. Chem. Phys.120, 6085 (2004)] models. The calculated melting temperature at 1 bar is T(m) = 229 +/- 1 K for the TIP4P and T(m) = 272.0 +/- 0.6 K for the TIP5P ice I(h), both are consistent with previous simulations based on free-energy methods. For the TIP4P-Ew and TIP5P-Ew models, the calculated melting temperature is T(m) = 257.0 +/- 1.1 K and T(m) = 253.9 +/- 1.1 K, respectively.

Journal Article↗