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Biomedical subjects

Xin Yu

Publications and source records attributed to Xin Yu.

At least 55 records · Page 3Linked to original sources
PubMed2004

ORFDB: an information resource linking scientific content to a high-quality Open Reading Frame (ORF) collection.

The ORFDB (http://orf.invitrogen.com/) represents an ongoing effort at Invitrogen Corporation to integrate relevant scientific data with an evolving collection of human and mouse Open Reading Frame (ORF) clones (Ultimate ORF Clones). The ORFDB serves as a central data warehouse enabling researchers to search the ORF collection through its web portal ORFBrowser, allowing researchers to find the Ultimate ORF clones by blast, keyword, GenBank accession, gene symbol, clone ID, Unigene ID, LocusLink ID or through functional relationships by browsing the collection via the Gene Ontology (GO) Browser. As of October 2003, the ORFDB contains 6200 human and 2870 mouse Ultimate ORF clones. All Ultimate ORF clones have been fully sequenced with high quality, and are matched to public reference protein sequences. In addition, the cloned ORFs have been extensively annotated across six categories: Gene, ORF, Clone Format, Protein, SNP and Genomic links, with the information assembled in a format termed the ORFCard. The ORFCard represents an information repository that documents the sequence quality, alignment with respect to public protein sequences, and the latest publicly available information associated with each human and mouse gene represented in the collection.

Animals↗
PubMed2004

Harmonic phase MR tagging for direct quantification of Lagrangian strain in rat hearts after myocardial infarction.

The utility of harmonic phase (HARP) analysis was recently demonstrated in humans and large animals as a technique for rapid and automatic analysis of tagged magnetic resonance images. In the current study, the applicability and accuracy of HARP analysis for automatic strain quantification in small animals were investigated. A validation study was performed on seven postinfarct rats and seven age-matched controls. A method for direct computation of 2D Lagrangian strain fields from spatial derivatives of HARP images was also developed in this paper. The results of HARP analysis were evaluated by comparison with those of homogeneous strain analysis employing finite element method and manual tag tracking. Both methods were validated with simulated digital images. Compared to conventional homogeneous strain analysis, HARP analysis yielded similar results in the assessment of regional strain patterns in both control and infarct rats. Both methods detected a reduction in maximal stretch and shortening in infarct rats. Our results suggest that HARP analysis can also be applied to quantify alterations in regional myocardial wall motion in small animals.

Animals↗
PubMed2004

Quantitative "magnetic resonance immunohistochemistry" with ligand-targeted (19)F nanoparticles.

Unstable atherosclerotic plaques exhibit microdeposits of fibrin that may indicate the potential for a future rupture. However, current methods for evaluating the stage of an atherosclerotic lesion only involve characterizing the level of vessel stenosis, without delineating which lesions are beginning to rupture. Previous work has shown that fibrin-targeted, liquid perfluorocarbon nanoparticles, which carry a high payload of gadolinium, have a high sensitivity and specificity for detecting fibrin with clinical (1)H MRI. In this work, the perfluorocarbon content of the targeted nanoparticles is exploited for the purposes of (19)F imaging and spectroscopy to demonstrate a method for quantifiable molecular imaging of fibrin in vitro at 4.7 T. Additionally, the quantity of bound nanoparticles formulated with different perfluorocarbon species was calculated using spectroscopy. Results indicate that the high degree of nanoparticle binding to fibrin clots and the lack of background (19)F signal allow accurate quantification using spectroscopy at 4.7 T, as corroborated with proton relaxation rate measurements at 1.5 T and trace element (gadolinium) analysis. Finally, the extension of these techniques to a clinically relevant application, the evaluation of the fibrin burden within an ex vivo human carotid endarterectomy sample, demonstrates the potential use of these particles for uniquely identifying unstable atherosclerotic lesions in vivo.

Arteriosclerosis↗
PubMed2004

Manganese-enhanced magnetic resonance imaging (MEMRI) of mouse brain development.

Given the importance of genetically modified mice in studies of mammalian brain development and human congenital brain diseases, MRI has the potential to provide an efficient in vivo approach for analyzing mutant phenotypes in the early postnatal mouse brain. The combination of reduced tissue contrast at the high magnetic fields required for mice, and the changing cellular composition of the developing mouse brain make it difficult to optimize MRI contrast in neonatal mouse imaging. We have explored an easily implemented approach for contrast-enhanced imaging, using systemically administered manganese (Mn) to reveal fine anatomical detail in T1-weighted MR images of neonatal mouse brains. In particular, we demonstrate the utility of this Mn-enhanced MRI (MEMRI) method for analyzing early postnatal patterning of the mouse cerebellum. Through comparisons with matched histological sections, we further show that MEMRI enhancement correlates qualitatively with granule cell density in the developing cerebellum, suggesting that the cerebellar enhancement is due to uptake of Mn in the granule neurons. Finally, variable cerebellar defects in mice with a conditional mutation in the Gbx2 gene were analyzed with MEMRI to demonstrate the utility of this method for mutant mouse phenotyping. Taken together, our results indicate that MEMRI provides an efficient and powerful in vivo method for analyzing neonatal brain development in normal and genetically engineered mice.

Aging↗
PubMed2004

No association between polymorphisms in three genes of cytochrome p450 family and paranoid schizophrenia in northern Chinese Han population.

We genotyped six SNPs in the genes of p450 family among paranoid schizophrenics and normal controls. All subjects are unrelated Han Chinese. Three showed polymorphic, and no significant differences in allele or genotype frequencies were detected between patients and controls. Thus we obtained no evidence for the involvement of the polymorphisms in paranoid schizophrenia in the population investigated.

Adult↗
PubMed2004

An association study between polymorphisms in three genes of 14-3-3 (tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein) family and paranoid schizophrenia in northern Chinese population.

We performed an association study between three SNPs in the genes of 14-3-3 family and paranoid schizophrenia. SNP rs983583 G/A in the YWHAZ gene showed significant association with paranoid schizophrenia. Our study indicated that the YWHAZ gene was a potential susceptibility gene for paranoid schizophrenia in the population studied.

Adult↗
PubMed2004

XBP1, downstream of Blimp-1, expands the secretory apparatus and other organelles, and increases protein synthesis in plasma cell differentiation.

The differentiation of B cells into immunoglobulin-secreting plasma cells is controlled by two transcription factors, Blimp-1 and XBP1. By gene expression profiling, we defined a set of genes whose induction during mouse plasmacytic differentiation is dependent on Blimp-1 and/or XBP1. Blimp-1-deficient B cells failed to upregulate most plasma cell-specific genes, including xbp1. Differentiating xbp1-deficient B cells induced Blimp-1 normally but failed to upregulate genes encoding many secretory pathway components. Conversely, ectopic expression of XBP1 induced a wide spectrum of secretory pathway genes and physically expanded the endoplasmic reticulum. In addition, XBP1 increased cell size, lysosome content, mitochondrial mass and function, ribosome numbers, and total protein synthesis. Thus, XBP1 coordinates diverse changes in cellular structure and function resulting in the characteristic phenotype of professional secretory cells.

Animals↗
PubMed2004

Reciprocal translocations in Saccharomyces cerevisiae formed by nonhomologous end joining.

Reciprocal translocations are common in cancer cells, but their creation is poorly understood. We have developed an assay system in Saccharomyces cerevisiae to study reciprocal translocation formation in the absence of homology. We induce two specific double-strand breaks (DSBs) simultaneously on separate chromosomes with HO endonuclease and analyze the subsequent chromosomal rearrangements among surviving cells. Under these conditions, reciprocal translocations via nonhomologous end joining (NHEJ) occur at frequencies of approximately 2-7 x 10(-5)/cell exposed to the DSBs. Yku80p is a component of the cell's NHEJ machinery. In its absence, reciprocal translocations still occur, but the junctions are associated with deletions and extended overlapping sequences. After induction of a single DSB, translocations and inversions are recovered in wild-type and rad52 strains. In these rearrangements, a nonrandom assortment of sites have fused to the DSB, and their junctions show typical signs of NHEJ. The sites tend to be between open reading frames or within Ty1 LTRs. In some cases the translocation partner is formed by a break at a cryptic HO recognition site. Our results demonstrate that NHEJ-mediated reciprocal translocations can form in S. cerevisiae as a consequence of DSB repair.

DNA Damage↗
PubMed2004

The role of aquaporin RWC3 in drought avoidance in rice.

Although the discovery of aquaporins in plants has resulted in a paradigm shift in the understanding of plant water relations, the relationship between aquaporins and drought resistance still remains elusive. From an agronomic viewpoint, upland rice is traditionally considered as showing drought avoidance. In the investigation of different morphological and physiological responses of upland rice (Oryza sativa L. spp indica cv. Zhonghan 3) and lowland rice (O. sativa L. spp japonica cv. Xiushui 63) to water deficit, we observed young leaf rolling and the remarkable decline of cumulative transpiration in the upland rice. The expression of water channel protein RWC3 mRNA was increased in upland rice at the early response (up to 4 h) to the 20% polyethylene glycol (PEG) 6000 treatment, whereas there was no significant expression changes in lowland rice. Protein levels were increased in upland rice and decreased in lowland rice at 10 h after the water deficit. The up-regulation of RWC3 in upland rice fits well with the knowledge that upland rice adopts the mechanism of drought avoidance. The physiological significance of this RWC3 up-regulation was then explored with the over-expression of RWC3 in transgenic lowland rice (O. sativa L. spp japonica cv. Zhonghua 11) controlled by a stress-inducible SWPA2 promoter. Compared to the wild-type plant, the transgenic lowland rice exhibited higher root osmotic hydraulic conductivity (Lp), leaf water potential and relative cumulative transpiration at the end of 10 h PEG treatment. These results indicated that RWC3 probably played a role in drought avoidance in rice.

Animals↗
PubMed2004

No association between polymorphisms in the DDC gene and paranoid schizophrenia in a northern Chinese population.

Several lines of evidence suggest that dysfunctions of neurotransmitters are associated with schizophrenia. DOPA decarboxylase (DDC) is an enzyme involved directly in the synthesis of dopamine and serotonin, and indirectly in the synthesis of noradrenaline. Therefore, the DDC gene can be considered a candidate gene for schizophrenia. We performed an association study between three single nucleotide polymorphisms in the DDC gene and paranoid schizophrenia. However, in our study no significant differences were found in the genotype distributions and allele frequencies between 80 paranoid schizophrenics and 108 controls for any of the polymorphisms. Neither did the haplotypes of the single nucleotide polymorphisms show any association with paranoid schizophrenia. Therefore, we conclude that the polymorphisms studied do not play a major role in paranoid schizophrenia pathogenesis in the population investigated.

Asian People↗
PubMed2004

Awareness and attitudes of healthcare professionals in Wuhan, China to the reporting of adverse drug reactions.

BACKGROUND: A voluntary procedure for reporting adverse drug reactions (ADRs) was formally put in place in 1989. However, only a small proportion of ADR reports are actually forwarded to the national monitoring center. To identify the reasons for underreporting, the authors investigated the awareness and attitudes of healthcare professionals (doctors, nurses, and administrators) toward the ADR system in China. In addition, the authors sought to formulate approaches to improve the current ADR reporting system. METHODS: Structured interviews were carried out in 16 hospitals selected from 27 municipal hospitals in Wuhan, Hubei Province, China. A questionnaire survey of a stratified random sample of approximately 15% of healthcare professionals in each selected hospital was conducted during February to March 2003. RESULTS: The response rate of this survey was 85%. One thousand six hundred and fifty-three questionnaires were used in the final analysis. Only 2.7% of the healthcare professionals had a correct understanding to the definition of ADR. Eighty-nine point two percent of the healthcare professionals had encountered ADRs. Ninety-four percent of them were aware of the need to report these to the ADR monitoring center. However, only 28.5% of doctors, 22.8% of nurses, and 29.7% of administrators actually submitted a report. For the most part, they reported ADRs to the hospital pharmacy (66.0%), to other departments in the hospital (72.5%), and to the pharmaceutical industry (23.0%), rather than to the national monitoring center (2.9%) or regional monitoring center (9.5%). Severe or rare ADRs and ADRs to new products were generally perceived to be significant enough to report. Sixty-two point one percent of the healthcare professionals had encountered ADRs, yet not reported them to anybody. The major reasons for not reporting included no knowledge of the reporting procedure (71.4%), unavailability of the reporting center mailing address (67.9%), unavailability of the ADR report form (60.4%), lack of knowledge of the existence of a national ADR reporting system (52.2%), and belief that the ADR in question was already well known (44.1%). CONCLUSIONS: Healthcare professionals in Wuhan, China have little basic knowledge of ADR and of the voluntary reporting system. The main reasons for underreporting were lack of basic knowledge about ADRs and the voluntary reporting procedure. Education and training of healthcare professionals is needed to improve the current ADR reporting system.

Adverse Drug Reaction Reporting Systems↗
PubMed2004

Inhibitory effect of retroviral vector containing anti-sense Smad4 gene on Ito cell line, LI90.

BACKGROUND: Transforming growth factor-beta1 (TGF-beta1) exerts strong fibrogenic potential in culture-activated HSCs. Smad4 is a key intracellular mediator for the transforming growth factor-beta (TGF-beta) superfamily of growth factors. The aim of this study was to assess the effects of the antisense Smad4 gene on Ito cell line, LI90. METHODS: The recombinant retroviral vector pLXSN-Smad4 was constructed by cloning the rat antisense Smad4 cDNA into the retroviral vector pLXSN. Retroviruses with or without the antisense gene were obtained by transfecting pLXSN-Smad4 and pLXSN vectors into PA317 cells. Human hepatic stellate cells (HSCs) LI90 were infected with these retroviruses followed by selection with G418. The expression of Smad4 was detected by Northern and Western blots. Cell biological characteristics, including cell growth curve, 3H-TdR and 3H-proline uptake by HSCs and the production of extracellular matrix were assessed. RESULTS: mRNA and protein expressions of Smad4 in LI90 cells transfected with retrovirus containing the antisense Smad4 gene were much lower than those in LI90 cells transfected with empty vector or parental LI90 cells. Cells hypoexpressing the Smad4 gene exhibited a slower rate of growth, a lower uptake of 3H-TdR and 3H-proline (P < 0.01), and smaller production of th extracellular matrix, compared with parental LI90 cells and cells transfected with empty retrovirus. CONCLUSIONS: The antisense Smad4 gene can suppress the expression of the Smad4 gene, reduce endogenous production of Smad4 mRNA and protein, block TGF-beta1 signaling pathway, inhibit activation of Ito cells, obstruct the growth of Ito cells, decrease the production of the extracellular matrix (ECM). Our results may provide a basis for the development of antifibrotic gene therapy.

Cell Line↗
PubMed2004

[Neuropsychiatric symptoms in dementia and elderly people in the community: results from the Beijing Dementia Cooperative Study].

OBJECTIVE: To determine the prevalence of neuropsychiatric symptoms in dementia and normal elderly people living in the Chinese community of Beijing. METHODS: A cross-sectional study derived from the Beijing Dementia Cooperative Study was carried out a population survey was carried out on a total of 1540 participants aged 65 years and older living in Beijing city and rural areas. All the individuals and 373 demented elderly people completed a series of neuropsychological examination and the Neuropsychiatric Inventory (NPI). RESULTS: Among the dementia participants, 49.33% had exhibited neuropsychiatric symptoms (35.66% rated as clinically significant), in which 80.4% reported 2 or more disturbances, with depression (23.86%), apathy (21.72%) and anxiety (20.38%) being most common. Of the 1540 normal individuals, 18.25% of them exhibited neuropsychiatric symptoms (6.49% rated as clinically significant), in which 53% reported 2 or more disturbances, with sleepless (10%), depression (8.9%) and anxiety (6.97%) being the most common. CONCLUSION: To our knowledge, this was the first multi-center study on neuropsychiatric disturbances in dementia and cognitive normal elderly people. Neuropsychiatric symptoms occurred mainly in persons with dementia and of clinical severity. Though the neuropsychiatric disturbances reported in cognitive normal individuals were lower and less serious compared to dementia, they should not be neglected. These finding suggested that a screening programme focusing on identifying these symptoms should be included in the physician's diagnostic tools for dementia.

Aged↗
PubMed2003

Molecular diagnosis of primary mediastinal B cell lymphoma identifies a clinically favorable subgroup of diffuse large B cell lymphoma related to Hodgkin lymphoma.

Using current diagnostic criteria, primary mediastinal B cell lymphoma (PMBL) cannot be distinguished from other types of diffuse large B cell lymphoma (DLBCL) reliably. We used gene expression profiling to develop a more precise molecular diagnosis of PMBL. PMBL patients were considerably younger than other DLBCL patients, and their lymphomas frequently involved other thoracic structures but not extrathoracic sites typical of other DLBCLs. PMBL patients had a relatively favorable clinical outcome, with a 5-yr survival rate of 64% compared with 46% for other DLBCL patients. Gene expression profiling strongly supported a relationship between PMBL and Hodgkin lymphoma: over one third of the genes that were more highly expressed in PMBL than in other DLBCLs were also characteristically expressed in Hodgkin lymphoma cells. PDL2, which encodes a regulator of T cell activation, was the gene that best discriminated PMBL from other DLBCLs and was also highly expressed in Hodgkin lymphoma cells. The genomic loci for PDL2 and several neighboring genes were amplified in over half of the PMBLs and in Hodgkin lymphoma cell lines. The molecular diagnosis of PMBL should significantly aid in the development of therapies tailored to this clinically and pathogenetically distinctive subgroup of DLBCL.

Adult↗
PubMed2003

Wiring of enzymes to electrodes by ultrathin conductive polyion underlayers: enhanced catalytic response to hydrogen peroxide.

Stable electroactive films were grown layer by layer on rough pyrolytic graphite electrodes featuring 4-nm underlayers of sulfonated polyaniline (SPAN) covered with a film containing myoglobin or horseradish peroxidase grown in alternating layers with poly(styrenesulfonate). The self-doped polyanionic SPAN layer, grown on a 2-nm polycation layer, was conductive between about 0.1 and -0.4 V vs SCE at pH 4.5. The enzyme films had the architecture PDDA/SPAN/(enzyme/PSS)3, where PDDA is poly(diallyldimethylammonium) ion. Comparisons of voltammetric measurements of electroactive protein with quartz crystal microbalance measurements of total protein showed that 90% or more of the protein was coupled to the electrode when the SPAN underlayer was present, as opposed to approximately 40% protein electroactivity when SPAN was absent. As a consequence of the highly efficient coupling between enzymes and electrode, the PDDA/SPAN/(enzyme/PSS)3 films exhibited a higher sensitivity for the electrochemical catalytic reduction of hydrogen peroxide. Amperometry at a rotating disk electrode at 0 V gave sensitivity for hydrogen peroxide up to 14 microA microM(-1) cm(-2) in the submicromolar concentration range and a detection limit of approximately 3 nM. Results suggest the future utility of ultrathin layers of conductive self-doping polyions in improving sensitivity of enzyme biosensors.

Animals↗
PubMed2003

Remodeling of cardiac fiber structure after infarction in rats quantified with diffusion tensor MRI.

Structural remodeling of myocardium after infarction plays a critical role in functional adaptation. Diffusion tensor magnetic resonance imaging (DTMRI) provides a means for rapid and nondestructive characterization of the three-dimensional fiber architecture of cardiac tissues. In this study, microscopic structural changes caused by MI were evaluated in Fischer 344 rats 4 wk after infarct surgery. DTMRI studies were performed on 15 excised, formalin-fixed rat hearts of both infarct (left anterior descending coronary artery occlusion, n = 8) and control (sham, n = 7) rats. Infarct myocardium exhibited increased water diffusivity (41% increase in trace values) and decreased diffusion anisotropy (37% decrease in relative anisotropy index). The reduced diffusion anisotropy correlated negatively with microscopic fiber disarray determined by histological analysis (R = 0.81). Transmural courses of fiber orientation angles in infarct zones were similar to those of normal myocardium. However, regional angular deviation of the diffusion tensor increased significantly in the infarct myocardium and correlated strongly with microscopic fiber disarray (R = 0.86). These results suggest that DTMRI may provide a valuable tool for defining structural remodeling in diseased myocardium at the cellular and tissue level.

Animals↗
PubMed2003

Morphine and endomorphins differentially regulate micro-opioid receptor mRNA in SHSY-5Y human neuroblastoma cells.

A sensitive quantitative-competitive reverse transcriptase-polymerase chain reaction method was developed to measure micro-opioid receptor (MOR) mRNA expression in SHSY-5Y neuroblastoma cells. Differentiation of SHSY-5Y cells with either retinoic acid (RA) or 12-o-tetradecanoyl-phorbol-13-acetate (TPA) significantly increased MOR mRNA levels. Morphine treatment (10 microM) for 24 h decreased MOR mRNA levels in control, as well as RA- and TPA-differentiated cells. In contrast, chronic exposure to the opioid peptides endomorphin-1 or endomorphin-2 significantly increased MOR mRNA levels in undifferentiated and RA-differentiated cells. An opioid antagonist, naloxone, reversed the morphine and endomorphin-1 and -2 effects on MOR mRNA levels in undifferentiated SHSY-5Y cells, but naloxone had differential reversing effects on the agonists' regulation of MOR mRNA in RA- or TPA-differentiated cells. To investigate whether the changes in MOR mRNA expression paralleled changes in MOR receptor function, intracellular cAMP accumulation in SHSY-5Y cells was measured. After chronic treatment with morphine, forskolin-induced cAMP levels in SHSY-5Y cells were significantly higher than those of untreated control cells. In contrast, forskolin-induced cAMP accumulation levels were lower in cells treated with endomorphin-1 or -2 than in untreated control cells. Together, our studies indicate that the opioid alkaloid morphine and the opioid peptides endomorphin-1 and -2 differentially regulate MOR mRNA expression and MOR function in SHSY-5Y cells.

Analgesics, Opioid↗