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Biomedical subjects

M Yang

Publications and source records attributed to M Yang.

At least 73 records · Page 4Linked to original sources
PubMed2002

Short-term responses of Oryzias latipes (Pisces: Adrianichthyidae) and Macrobrachium nipponense (Crustacea: Palaemonidae) to municipal and pharmaceutical waste water in Beijing, China: survival, behaviour, biochemical biomarkers.

Whole effluent toxicity was assessed for the fish Oryzias latipes and the prawn Macrobrachium nipponense for 18 h in a dilution series (0-66%) of the inflow and effluent of a municipal waste water treatment plant as well as waste water from a teramycin producing pharmaceutical industry, before, during and after a pilot laboratory purification process. The waste waters caused acute toxicity as measured by inhibition of light emission in the luminiscent bacterium Vibrio qingaiensis sp. nov. (Q67). EROD and aryl hydrocarbon hydroxylase activity in in vitro carp liver-cells showed a dose-dependent toxic response to the municipal waste water. Behavioural responses and time-to-death of fish and prawn, recorded online with the "Multispecies Freshwater Biomonitor" proved to be concentration- and time-dependent sensitive toxicity indicators in both types of waste water. Behaviour changed stepwise from normal activity to (increased or decreased) activity to more time spent on ventilation and finally to increased morbidity at higher concentration and time of exposure. The municipal waste water treatment plant managed to reduce toxicity to bacteria (Q67), prawn and fish. The pharmaceutical waste water treatment process still has to be improved, in order to reduce toxicity for fish and prawn.

Animals↗
PubMed2002

Role of interleukin-13 in eosinophil accumulation and airway remodelling in a mouse model of chronic asthma.

BACKGROUND: Interleukin-13 is believed to be important in asthmatic inflammation and airway hyper-reactivity. OBJECTIVE: To investigate the role of IL-13 in chronic asthma, using an improved experimental model of asthma that reproduces most of the morphological features of the human disease. METHODS: BALB/c mice or gene-targeted mice deficient in their ability to produce IL-13 or the IL-4 receptor alpha-chain (IL-4Ralpha) were sensitized to ovalbumin and exposed to aerosolized antigen for 30 min/day on 3 days/week for 6 weeks. Intraepithelial eosinophils, accumulation of chronic inflammatory cells in the airway wall, subepithelial fibrosis, epithelial hypertrophy and numbers of mucous cells were quantified histomorphometrically. Airway hyper-reactivity (AHR) to a cholinergic agonist was assessed by barometric plethysmography. RESULTS: Compared with wild-type animals, IL-13 -/- mice exhibited diminished accumulation of eosinophils and chronic inflammatory cells, as well as reduced subepithelial fibrosis, epithelial hypertrophy and mucous cell hyperplasia (P < 0.01 for all comparisons). In contrast, AHR was still demonstrable in IL -13 -/- mice. In IL-4Ralpha -/- mice the inflammatory response, subepithelial fibrosis and AHR were similar to wild-type mice, although the receptor-deficient mice had significantly less epithelial hypertrophy and mucous cell hyperplasia. CONCLUSION: These results imply a critical role for IL-13 in accumulation of intraepithelial eosinophils in chronic asthma, as well as in epithelial and subepithelial remodelling. In addition, they suggest that in chronic asthma, IL-13 may be capable of signalling via a pathway that does not involve IL-4Ralpha.

Animals↗
PubMed2002

Treatment of antibiotics wastewater utilizing successive hydrolysis, denitrification and nitrification.

A process consisting of anaerobic hydrolysis, denitrification, and oxidation/nitrification was proposed for simultaneous removal of carbon and nitrogen from terramycin crystallizing mother solution (TCMS), and its performance was investigated by treating diluted TCMS in a lab-scale continuous flow column system. Direct denitrification-nitrification of diluted TCMS produced a significant residual of nitrate and nitrite, which disappeared 44 days after startup of anaerobic hydrolysis column. The electron donors available to denitrification were increased by 6 times after diluted TCMS was treated in the hydrolysis column under an HRT of 2.5 h or longer. The reaction rates of organics decomposition, nitrification, and denitrification were also significantly increased due to reduction of terramycin and decomposition of complicated molecules to small molecules during anaerobic hydrolysis. The specific denitrification rate and nitrification rate increased from 0.033 d(-1) and 0.01 d(-1) to 0.045 d(-1) and 0.021 d(-1) respectively after diluted TCMS (dilution ratio: 1:4) was hydrolyzed in anaerobic hydrolysis column at a hydraulic retention time (HRT) of 4 h.

Anti-Bacterial Agents↗
PubMed2002

Case report: gastric schwannoma: MRI findings.

MRI features are described in a case of gastric schwannoma. A large, discretely marginated, multilobular mass was seen adjacent to the gastric antrum with the epicentre of the mass in the gastrocolic ligament. The overall signal pattern was low on T(1) weighted images and moderate to markedly elevated on T(2) weighted images. Post-gadolinium sequences demonstrate slow but fairly uniform enhancement throughout the mass.

Humans↗
PubMed2001

Non-derivatization approach to high-performance liquid chromatography-fluorescence detection for aminoglycoside antibiotics based on a ligand displacement reaction.

An indirect fluorescence detection method has been developed for detecting the aminoglycoside antibiotics following chromatographic separation. This approach to detection is based on a displacement reaction between the aminoglycosides and a copper(II)-L-tryptophan (L-Trp) complex, Cu(L-Trp)2. The aminoglycosides, which contain multiple amino groups, have strong affinities for the Cu(II) ion and displace L-Trp from the Cu(L-Trp)2 complex. The resulting increase in L-Trp fluorescence, which is quenched when coordinated to Cu(II), is indicative of the presence of the aminoglycoside. Fluorescence titration data indicate that there is a stoichiometric ratio of 1:1 between the reaction of the aminoglycosides with Cu(L-Trp)2. This HPLC detection scheme is implemented postcolumn by mixing a buffered Cu(L-Trp)2 solution with the column eluent prior to detection. The aminoglycosides were separated with the use of a column packed with a polymeric strong cation-exchanger. Separation and detection variables were optimized and are discussed. The detection limits for the aminoglycosides tested ranged from 4.2 to 14.5 ng injected (S/N=3). A linear working curve was achieved for amikacin in the range of 29-586 ng for a six point linearity test. The developed separation and detection scheme was further tested by analyzing commercial pharmaceutical formulations of these antibiotics.

Aminoglycosides↗
PubMed2001

Solid-phase microextraction of monocyclic aromatic amines using novel fibers coated with crown ether.

Three solid-phase microextraction (SPME) fibers prepared by the sol-gel method, containing hydroxydibenzo-14-crown-4 (OH-DB14C4), dihydroxy-substituted saturated urushiol crown ether (DHSU14C4) and 3,5-dibutyl-unsymmetry-dibenzo-14-crown-4-dihydroxy crown ether (DBUD14C4), respectively, were evaluated for the determination of aromatic amine (aniline, m-toluidine, N,N-diethylaniline, N-ethyl-m-toluidine, 3,4-dimethylaniline). The sol-gel-derived hydroxy-dibenzo14-crown-4-coated fiber has the best affinity for several aniline derivatives. Optimization was carried out for the determination of aromatic amines with SPME fibers. The linearity was from 0.11 to 29 microg/ml and detection limits varied from 0.17 to 0.98 ng/ml. Relative standard deviation (n=5) was found to be 3.23-6.20%. The coating proved to be very stable at high temperature (to 340 degrees C) and in different solvents (organic and inorganic). The method was applied to the determination of aromatic amines in wastewater samples from a pharmaceutical factory.

Amines↗
PubMed2001

Progress toward analysis of D8/17 binding to B cells in children with obsessive compulsive disorder and/or chronic tic disorder.

BACKGROUND: Previous research has suggested that a subgroup of children with obsessive compulsive disorder (OCD) have neuropsychiatric sequelae of streptococcal pharyngitis, similar to that seen in the neurological manifestation of rheumatic fever (RF). Monoclonal antibody D8/17 demonstrates increased binding to B cells in patients with RF and in patients with neuropsychiatric disorders using immunofluorescent microscopy. OBJECTIVE: The aim of this study was to determine if an earlier immunofluorescent microscopy study of monoclonal antibody D8/17 in childhood-onset OCD and/or chronic tic disorder (CTD) could be replicated using the more objective method of flow cytometric analysis. METHOD: D8/17 binding to B cells was determined in patients with OCD and or CTD (N=32), and healthy controls (N=12) by flow cytometric analysis. RESULTS: Subjects with OCD/CTD showed increased mean cell binding (26.0%) of monoclonal antibody compared with healthy controls (9.1%) (p<0.001). When using the threshold of greater than 19% binding (95% upper confidence interval) as a measure of positivity, 65.6% of patients compared with 8.3% of controls showed increased antibody binding to B cells (p=0.01). CONCLUSIONS: Although this study reports positive results, many methodological issues will need to be addressed before generalized use of assay for diagnostic purposes.

Adolescent↗
PubMed2001

A new route to hindered tertiary amines.

The Rh(2)(OAc)(4)-stabilized carbenoid derived from dimethyl diazomalonate has been found to insert into the N-H bond of sterically hindered secondary aliphatic amines to afford hindered tertiary aliphatic amines in quite satisfactory yields. For example dimethyl 2-(dicyclohexylamino)propanedioate was formed in 85% yield from dicyclohexylamine, and the severely hindered dimethyl 2-(2,2,6,6-tetramethyl-1-piperidinyl)propanedioate was formed in 38% yield from 2,2,6,6-tetramethylpiperidine. The Rh(2)(OAc)(4) - dimethyl diazomalonate reaction was found to work also for arylalkylamines and diarylamines. In these cases, small amounts of products resulting from formal insertion of the carbenoid into an aromatic C-H bond were detected. Substitution at ortho positions caused the yield of C-H insertion products to increase. Other diazo compounds, viz. ethyl diazoacetoacetate, 2-diazocyclohexane-1,3-dione, and 2-diazo-5,5-dimethylcyclohexane-1,3-dione, performed satisfactorily in Rh(2)(OAc)(4)-catalyzed reactions with arylalkylamines and diarylamines, but led to complicated reaction mixtures with dialkylamines.

Journal Article↗
PubMed2001

Constitutive activation of NF-kappa B and secretion of interleukin-8 induced by the G protein-coupled receptor of Kaposi's sarcoma-associated herpesvirus involve G alpha(13) and RhoA.

The Kaposi's sarcoma herpesvirus (KSHV) open reading frame 74 encodes a G protein-coupled receptor (GPCR) for chemokines. Exogenous expression of this constitutively active GPCR leads to cell transformation and vascular overgrowth characteristic of Kaposi's sarcoma. We show here that expression of KSHV-GPCR in transfected cells results in constitutive transactivation of nuclear factor kappa B (NF-kappa B) and secretion of interleukin-8, and this response involves activation of G alpha(13) and RhoA. The induced expression of a NF-kappa B luciferase reporter was partially reduced by pertussis toxin and the G beta gamma scavenger transducin, and enhanced by co-expression of G alpha(13) and to a lesser extent, G alpha(q). These results indicate coupling of KSHV-GPCR to multiple G proteins for NF-kappa B activation. Expression of KSHV-GPCR led to stress fiber formation in NIH 3T3 cells. To examine the involvement of the G alpha(13)-RhoA pathway in KSHV-GPCR-mediated NF-kappa B activation, HeLa cells were transfected with KSHV-GPCR alone and in combination with the regulator of G protein signaling (RGS) from p115RhoGEF or a dominant negative RhoA(T19N). Both constructs, as well as the C3 exoenzyme from Clostritium botulinum, partially reduced NF-kappa B activation by KSHV-GPCR, and by a constitutively active G alpha(13)(Q226L). KSHV-GPCR-induced NF-kappa B activation is accompanied by increased secretion of IL-8, a function mimicked by the activated G alpha(13) but not by an activated G alpha(q)(Q209L). These results suggest coupling of KSHV-GPCR to the G alpha(13)-RhoA pathway in addition to other G proteins.

DNA-Binding Proteins↗
PubMed2001

Effect of receptor phosphorylation on the binding between IRS-1 and IGF-1R as revealed by surface plasmon resonance biosensor.

A receptor binding assay based on the surface plasmon resonance (SPR) biosensor technique was developed to study the interaction between insulin-like growth factor-1 receptor (IGF-1R) and its intracellular substrate protein insulin receptor substrate-1 (IRS-1). The sensor surface was modified with anti-IGF-1R (alpha-subunit) monoclonal antibodies for the capturing of the receptor-containing membrane fragments from cell lysates. The IGF-1R was successfully immobilized on the sensor surface with binding capability for its intracellular substrates. SPR measurements showed that the tyrosine phosphorylation of IGF-1R induced by its extracellular ligand insulin-like growth factor-1 caused the receptor to bind with IRS-1 10 times faster than the unactivated receptor. As a result, the affinity constants of IRS-1 to phosphorylated and unphosphorylated IGF-1R were (8.06+/-5.18)x10(9) M(-1) and (9.81+/-4.61)x10(8) M(-1), respectively.

3T3 Cells↗
PubMed2001

IL-13 induces airways hyperreactivity independently of the IL-4R alpha chain in the allergic lung.

The potent spasmogenic properties of IL-13 have identified this molecule as a potential regulator of airways hyperreactivity (AHR) in asthma. Although IL-13 is thought to primarily signal through the IL-13Ralpha1-IL-4Ralpha complex, the cellular and molecular components employed by this cytokine to induce AHR in the allergic lung have not been identified. By transferring OVA-specific CD4(+) T cells that were wild type (IL-13(+/+) T cells) or deficient in IL-13 (IL-13(-/-) T cells) to nonsensitized mice that were then challenged with OVA aerosol, we show that T cell-derived IL-13 plays a key role in regulating AHR, mucus hypersecretion, eotaxin production, and eosinophilia in the allergic lung. Moreover, IL-13(+/+) T cells induce these features (except mucus production) of allergic disease independently of the IL-4Ralpha chain. By contrast, IL-13(+/+) T cells did not induce disease in STAT6-deficient mice. This shows that IL-13 employs a novel component of the IL-13 receptor signaling system that involves STAT6, independently of the IL-4Ralpha chain, to modulate pathogenesis. We show that this novel pathway for IL-13 signaling is dependent on T cell activation in the lung and is critically linked to downstream effector pathways regulated by eotaxin and STAT6.

Adoptive Transfer↗
PubMed2001

Spatial-temporal imaging of bacterial infection and antibiotic response in intact animals.

We describe imaging the luminance of green fluorescent protein (GFP)-expressing bacteria from outside intact infected animals. This simple, nonintrusive technique can show in great detail the spatial-temporal behavior of the infectious process. The bacteria, expressing the GFP, are sufficiently bright as to be clearly visible from outside the infected animal and recorded with simple equipment. Introduced bacteria were observed in several mouse organs including the peritoneal cavity, stomach, small intestine, and colon. Instantaneous real-time images of the infectious process were acquired by using a color charge-coupled device video camera by simply illuminating mice at 490 nm. Most techniques for imaging the interior of intact animals may require the administration of exogenous substrates, anesthesia, or contrasting substances and require very long data collection times. In contrast, the whole-body fluorescence imaging described here is fast and requires no extraneous agents. The progress of Escherichia coli-GFP through the mouse gastrointestinal tract after gavage was followed in real-time by whole-body imaging. Bacteria, seen first in the stomach, migrated into the small intestine and subsequently into the colon, an observation confirmed by intravital direct imaging. An i.p. infection was established by i.p. injection of E. coli-GFP. The development of infection over 6 h and its regression after kanamycin treatment were visualized by whole-body imaging. This imaging technology affords a powerful approach to visualizing the infection process, determining the tissue specificity of infection, and the spatial migration of the infectious agents.

Administration, Oral↗
PubMed2001

Different classifications of UPOs in the parametrically different chaotic ISI series of a neural pacemaker.

Various interspike intervals (ISIs) in a series of spontaneous discharges of experimental neural pacemakers were identified as chaotic and as lying between stable period 2 and stable period 3. The method of So et al. for detection of unstable periodic orbits (UPOs) was applied to analyze two chaotic ISI series generated under the action of [Ca2+]o in different concentrations. In the chaotic ISI series near the stable period 2, an unstable period 2 orbit was detected. In the chaotic ISI series near the stable period 3, both an unstable period 2 orbit and an unstable period 3 orbit were detected. The location of the unstable period 2 orbit was close to that of the stable period 2 in the return map, while the location of the unstable period 3 orbit was close to that of the stable period 3. The results not only revealed the structures of various chaotic ISI series, but also indicated that the classification of UPOs could reflect the experimental control parameters at which the chaotic ISI series were generated. The previously discovered period adding bifurcation in the ISI series generated by experimental neural pacemakers [12] was further described in terms of the evolution of the period orbits.

Action Potentials↗
PubMed2001

A new locus for hereditary gingival fibromatosis (GINGF2) maps to 5q13-q22.

Gingival fibromatosis (GINGF) is an oral disorder characterized by enlargement of the gingiva. It occurs either as the sole phenotype or combined with other symptoms. Thus far, one GINGF locus has been mapped on chromosome 2, at 2p21, and a second possible locus has been mapped to 2p13. However, the genes responsible for this disorder have not been elucidated. We identified a four-generation Chinese GINGF family in which the disease manifests within 1 year after birth. After exclusion of the two known GINGF loci in this family, we performed a genome-wide search to map the chromosome location of the responsible gene. We identified a new locus, GINGF2, on chromosome 5q13-q22 with a maximum two-point lod score of 4.31 at D5S1721 (theta = 0.00). Haplotype analysis placed the critical region in the interval defined by D5S1491 and D5S1453. Within this region, calcium/calmodulin-dependent protein kinase IV (CAMK4) is a strong candidate.

Age of Onset↗
PubMed2001

G alpha 16 couples chemoattractant receptors to NF-kappa B activation.

The guanine nucleotide-binding regulatory protein alpha-subunit, Galpha(16), is primarily expressed in hemopoietic cells, and interacts with a large number of seven-membrane span receptors including chemoattractant receptors. We investigated the biological functions resulting from Galpha(16) coupling of chemoattractant receptors in a transfected cell model system. HeLa cells expressing a kappaB-driven luciferase reporter, Galpha(16), and the formyl peptide receptor responded to fMLP with a approximately 7- to 10-fold increase in luciferase activity. This response was accompanied by phosphorylation of IkappaBalpha and elevation of nuclear kappaB-DNA binding activity, indicating activation of NF-kappaB. In contrast to Galpha(16), expression of Galpha(q), Galpha(13), and Galpha(i2) resulted in a marginal increase in kappaB luciferase activity. A GTPase-deficient, constitutively active Galpha(16) mutant (Q212L) could replace agonist stimulation for activation of NF-kappaB. Furthermore, expression of Galpha(16) (Q212L) markedly enhanced TNF-alpha-induced kappaB reporter activity. The Galpha(16)-mediated NF-kappaB activation was paralleled by an increase in phospholipase C-beta activity, and was blocked by pharmacological inhibitors of protein kinase C (PKC) and by buffering of intracellular Ca(2+). The involvement of a conventional PKC isoform was confirmed by the finding that expression of PKCalpha enhanced the effect of Galpha(16), and a dominant negative PKCalpha partially blocked Galpha(16)-mediated NF-kappaB activation. In addition to formyl peptide receptor, Galpha(16) also enhanced NF-kappaB activation by the C5a and C3a receptors, and by CXC chemokine receptor 2 and CCR8. These results suggest a potential role of Galpha(16) in transcriptional regulation downstream of chemoattractant receptors.

Active Transport, Cell Nucleus↗
PubMed2001

Phosphorus limitation of nitrogen fixation by Trichodesmium in the central Atlantic Ocean.

Marine fixation of atmospheric nitrogen is believed to be an important source of biologically useful nitrogen to ocean surface waters, stimulating productivity of phytoplankton and so influencing the global carbon cycle. The majority of nitrogen fixation in tropical waters is carried out by the marine cyanobacterium Trichodesmium, which supplies more than half of the new nitrogen used for primary production. Although the factors controlling marine nitrogen fixation remain poorly understood, it has been thought that nitrogen fixation is limited by iron availability in the ocean. This was inferred from the high iron requirement estimated for growth of nitrogen fixing organisms and the higher apparent densities of Trichodesmium where aeolian iron inputs are plentiful. Here we report that nitrogen fixation rates in the central Atlantic appear to be independent of both dissolved iron levels in sea water and iron content in Trichodesmium colonies. Nitrogen fixation was, instead, highly correlated to the phosphorus content of Trichodesmium and was enhanced at higher irradiance. Furthermore, our calculations suggest that the structural iron requirement for the growth of nitrogen-fixing organisms is much lower than previously calculated. Although iron deficiency could still potentially limit growth of nitrogen-fixing organisms in regions of low iron availability-for example, in the subtropical North Pacific Ocean-our observations suggest that marine nitrogen fixation is not solely regulated by iron supply.

Atlantic Ocean↗