Biomedical subjects

Xiao-Ying Yu

Publications and source records attributed to Xiao-Ying Yu.

7 recordsLinked to original sources

PubMed2006

Analysis of anions in ambient aerosols by microchip capillary electrophoresis.

We describe a microchip capillary electrophoresis method for the analysis of nitrate and sulfate in ambient aerosols. Investigating the chemical composition of ambient aerosol particles is essential for understanding their sources and effects. Significant progress has been made towards developing mass spectrometry-based instrumentation for rapid qualitative analysis of aerosols. Alternative methods for rapid quantification of selected high abundance compounds are needed to augment the capacity for widespread routine analysis. Such methods could provide much higher temporal and spatial resolution than can be achieved currently. Inorganic anions comprise a large percentage of particulate mass, with nitrate and sulfate among the most abundant species. While ion chromatography has proven very useful for analyzing extracts of time-integrated ambient aerosol samples collected on filters and for semi-continuous, on-line particle composition measurements, there is a growing need for development of new compact, inexpensive approaches to routine on-line aerosol ion analysis for deployment in spatially dense, atmospheric measurement networks. Microchip capillary electrophoresis provides the necessary speed and portability to address this need. In this report, on-column contact conductivity detection is used with hydrodynamic injection to create a simple microchip instrument for analysis of nitrate and sulfate. On-column contact conductivity detection was achieved using a Pd decoupler placed upstream from the working electrodes. Microchips containing two Au or Pd working electrodes showed a good linear range (5-500 microM) and low limits-of-detection for sulfate and nitrate, with Au providing the lowest detection limits (1 microM) for both ions. The completed microchip system was used to analyze ambient aerosol filter samples. Nitrate and sulfate concentrations measured by the microchip matched the concentrations measured by ion chromatography.

Journal Article↗

PubMed2005

SLC18A2 promoter haplotypes and identification of a novel protective factor against alcoholism.

The vesicular monoamine transporter 2 (VMAT2, SLC18A2) takes up cytosolic monoamines into intracellular secretory vesicles, preventing their neurotoxicity in the cytosol and discharging them into extracellular space by exocytosis. It has been shown that one-copy deletion of the VMAT2 gene increases locomotion activity significantly in response to drug treatments and dopamine neuron death rate in response to neurotoxin treatments in knockout mice. Little is known about promoter polymorphisms and their influence on SLC18A2 promoter activity. We have re-sequenced a 17.4 kb DNA in the SLC18A2 promoter region for Caucasians and revealed 47 polymorphisms that confer 13 haplotypes. One of the haplotypes reaches a frequency as high as 65%, likely due to positive selection. In vitro analysis showed a 20% difference in promoter activity between two frequent haplotypes and identified some of the polymorphisms that influence promoter activity. Four haplotype-defining single nucleotide polymorphisms (hdSNPs) can define the frequent haplotypes and by genotyping these hdSNPs, we find that haplotypes with -14234G and -2504C of SLC18A2 promoter region represent a protective factor against alcoholism (P = 0.0038 by Fisher's exact tests). Therefore, SLC18A2 promoter haplotypes defined here create a foundation for transcriptional characterization of individuality and for association study on monoamine-related human diseases.

Alcoholism↗

PubMed2005

Particulate nitrate measurement using nylon filters.

Nylon filters are a popular medium to collect atmospheric fine particles in different aerosol monitoring networks, including those operated by the U.S. Environmental Protection Agency and the Interagency Monitoring of Protected Visual Environments (IMPROVE) program. Extraction of the filters by deionized water or by a basic aqueous solution (typically a mixture of sodium carbonate and sodium bicarbonate) is often performed to permit measurement of the inorganic ion content of the collected particles. Whereas previous studies have demonstrated the importance of using a basic solution to efficiently extract gaseous nitric acid collected using nylon filters, there has been a recent movement to the use of deionized water for extraction of particles collected on nylon filters to eliminate interference from sodium ion (Na+) during ion chromatographic analysis of inorganic aerosol cations. Results are reported here from a study designed to investigate the efficiency of deionized water extraction of aerosol nitrate (NO3-) and sulfate from nylon filters. Data were obtained through the conduct of five field experiments at selected IMPROVE sites. Results indicate that the nylon filters provide superior retention of collected fine particle NO3-, relative to Teflon filters, and that deionized water extraction (with ultrasonication) of collected NO3- and sulfate is as efficient, for the situations studied, as extraction using a basic solution of 1.7 mM sodium bicarbonate and 1.8 mM sodium carbonate.

Aerosols↗

PubMed2004

Expression of genes for B7-H3 and other T cell ligands by nasal epithelial cells during differentiation and activation.

Epithelial cells of the human respiratory tract express human leukocyte antigen (HLA) and the costimulatory molecules B7-1 and B7-2. Little is known, however, about the constitutive expression of genes encoding for the more recently identified members of the B7 homolog family of costimulatory molecules or about the influence of cellular differentiation and cytokines on their activity or on that of HLA or B7-1 and B7-2. Human nasal epithelial (HNE) cells were grown at the air-liquid interface (ALI) for 2 or 21 days to model in vivo conditions. Expression of genes for HLA-B and HLA-DR1 increased during mucociliary differentiation during this period and became more similar to HNE cells obtained fresh by brush biopsy from nasal turbinates. Gene transcripts for B7-H3 and B7-H2 were abundantly expressed in cells cultured at the ALI, but neither their activities nor that of B7-2 was significantly altered during differentiation. IFN-gamma and TNF-alpha upregulated mRNA encoding for both HLA molecules, but not for the B7 molecules. This study describes, for the first time, the expression of B7-H3 and B7-H2 by HNE cells and thus expands the range of potential costimulatory signals through which these cells may interact with activated mucosal T lymphocytes. In addition, the results suggest that the extent of mucociliary differentiation of cultured cells may influence this capability.

Antigens, CD↗

PubMed2004

mRNA for genes associated with antigen presentation are expressed by human middle meatal epithelial cells in culture.

OBJECTIVES/HYPOTHESIS: Although the mechanisms underlying the initiation and maintenance of inflammation in chronic rhinosinusitis are poorly understood, the activation of memory T cells within the nasal mucosa is thought to play an important role. T-cell activation requires specialized antigen processing and presentation of antigen by immunocompetent cells in the context of cell surface immune molecules. The purpose of this study was to investigate the expression of such molecules by human sinonasal epithelial cells grown in culture at the air-liquid interface (ALI). METHODS: Middle meatal epithelium was obtained from six patients undergoing endoscopic sinus surgery. Dissociated epithelial cells were grown to confluence in serum-free, defined medium and transferred to filter inserts for culture at the ALI. Cells were harvested at 2 and 21 days of growth at the ALI and processed for real-time polymerase chain reaction (PCR). The presence and relative abundance of constitutively expressed mRNA for human leukocyte antigen (HLA)-B, HLA-DR, B7 to 1, B7 to 2, B7-H2, B7-H3, and cathepsin D were assessed. RESULTS: After 2 days at the ALI, middle meatal epithelial cells demonstrated expression of genes for each of the antigen processing associated genes tested. The expression of HLA-B and HLA-DR increased significantly with cellular maturation at the ALI. Expression of HLA-DR and B7 to 1 increased with cytokine stimulation. CONCLUSIONS: Primary human epithelial cells obtained from the middle meatus express genes associated with antigen presentation function. The pattern of gene expression is modulated by cytokine stimulation and changes as the cells differentiate at the ALI. These findings suggest that mature middle meatal epithelial cells have the cellular machinery to interact with T cells and therefore may be direct participants in the modulation of T-cell activity in chronic sinusitis.

Antigen Presentation↗

PubMed2004

The human serotonin receptor 2B: coding region polymorphisms and association with vulnerability to illegal drug abuse.

OBJECTIVE AND METHODS: 5-Hydroxytryptamine (serotonin) receptor 2B (HTR2B) is involved in brain development. Although expressed in the human brain, HTR2B has not been investigated much for its role in higher brain functions. Here we describe a genome-scan with 391 simple sequence repeat markers in 300 Caucasians, identifying HTR2B gene as a candidate for drug abuse vulnerability. RESULTS: From DNA re-sequencing of 110 subjects, we discovered three novel single nucleotide polymorphisms (SNPs), two of which confer a double-mutant of the receptor protein in a drug-abusing population. Arg6, a conserved basic residue, and the conserved acidic Glu42 are mutated simultaneously into Gly, termed R6G/E42G. Furthermore, this double-mutant tends to associate with drug abuse (P = 0.08 by chi2 test). The third SNP that is a synonymous mutation in the codon of Gln11 showed significant association with drug abuse (P = 0.0335 by Fisher's exact test). CONCLUSION: Our data are the first suggesting that HTR2B contributes to brain architecture and pathways that are involved in illegal drug reward.

Adult↗

PubMed2002

Synergism between rhinovirus infection and oxidant pollutant exposure enhances airway epithelial cell cytokine production.

Of the several factors believed to exacerbate asthmatic symptoms, air pollution and viral infections are considered to be particularly important. Although evidence indicates that each of these respiratory insults individually can increase asthma severity in susceptible individuals, we know little about the extent to which exposure to environmental oxidant pollutants can influence the course of respiratory viral infection and its associated inflammation. To investigate the interaction of these two stimuli within their common epithelial cell targets in the upper and lower respiratory tracks, we infected primary human nasal epithelial cells and cells of the BEAS-2B line grown at the air-liquid interface with human rhinovirus type 16 (RV16) and exposed them to NO2 (2.0 ppm) or O3 (0.2 ppm) for 3 hr. Independently, RV16, NO2, and O3 rapidly increased release of the inflammatory cytokine interleukin-8 through oxidant-dependent mechanisms. The combined effect of RV16 and oxidant ranged from 42% to 250% greater than additive for NO2 and from 41% to 67% for O3. We abrogated these effects by treating the cells with the antioxidant N-acetylcysteine. Surface expression of intercellular adhesion molecule 1 (ICAM-1) underwent additive enhancement in response to combined stimulation. These data indicate that oxidant pollutants can amplify the generation of proinflammatory cytokines by RV16-infected cells and suggest that virus-induced inflammation in upper and lower airways may be exacerbated by concurrent exposure to ambient levels of oxidants commonly encountered the indoor and outdoor environments.

Cell Culture Techniques↗