Biomedical subjects

Ying Liu

Publications and source records attributed to Ying Liu.

At least 73 records · Page 4Linked to original sources

PubMed2006

Hepatitis B virus x gene and cyanobacterial toxins promote aflatoxin B1-induced hepatotumorigenesis in mice.

AIM: To assess the combinative role of aflatoxin B1(AFB1), cyanobacterial toxins (cyanotoxins), and hepatitis B virus (HBV) x gene in hepatotumorigenicity. METHODS: One-week-old animals carrying HBV x gene and their wild-type littermates were intraperitoneally (ip) injected with either single-dose AFB1 [6 mg/kg body weight (bw)], repeated-dose cyanotoxins (microcystin-LR or nodularin, 10 microg/kg bw once a week for 15 wk), DMSO (vehicle control) alone, or AFB1 followed by cyanotoxins a week later, and were sacrificed at 24 and 52 wk post-treatment. RESULTS: AFB1 induced liver tumors in 13 of 29 (44.8%) transgenic mice at 52 wk post-treatment, significantly more frequent than in wild-type mice (13.3%). This significant difference was not shown in the 24-wk study. Compared with AFB1 exposure alone, MC-LR and nodularin yielded approximately 3-fold and 6-fold increases in the incidence of AFB(1)-induced liver tumors in wild-type animals at 24 wk, respectively. HBV x gene did not further elevate the risk associated with co-exposure to AFB1 and cyanotoxins. With the exception of an MC-LR-dosed wild-type mouse, no liver tumor was observed in mice treated with cyanotoxins alone at 24 wk. Neither DMSO-treated transgenic mice nor their wild-type littermates had pathologic alterations relevant to hepatotumorigenesis in even up to 52 wk. CONCLUSION: HBV x gene and nodularin promote the development of AFB(1)-induced liver tumors. Co-exposure to AFB1 and MC-LR tends to elevate the risk of liver tumors at 24 wk relative to exposure to one of them. The combinative effect of AFB1, cyanotoxins and HBVx on hepatotumorigenesis is weak at 24 wk.

Aflatoxin B1↗

PubMed2006

High resolution spectral differentiation of enantiomers: benzo[a]pyrene tetrols complexed with a promiscuous antibody.

The interaction of the highly cross-reactive anti-PAH monoclonal antibody with four diastereomeric benzo[a]pyrene tetrols (BPTs) is studied by means of fluorescence line-narrowing spectroscopy. It is shown that the interaction of enantiomers of cis-BPT and trans-BPT with the antibody involves different complex geometries. These spatially different ligand-protein interactions alter the relative intensities of the excited-state vibrational frequencies of immunocomplexed molecules allowing for unambiguous spectroscopic resolution of all four enantiomeric isomers. This study represents the first example of a high-resolution, fluorescence-based spectroscopic method capable of enantiospecific differentiation.

Antibodies, Monoclonal↗

PubMed2006

Genome wide profiling of human embryonic stem cells (hESCs), their derivatives and embryonal carcinoma cells to develop base profiles of U.S. Federal government approved hESC lines.

BACKGROUND: In order to compare the gene expression profiles of human embryonic stem cell (hESC) lines and their differentiated progeny and to monitor feeder contaminations, we have examined gene expression in seven hESC lines and human fibroblast feeder cells using Illumina bead arrays that contain probes for 24,131 transcript probes. RESULTS: A total of 48 different samples (including duplicates) grown in multiple laboratories under different conditions were analyzed and pairwise comparisons were performed in all groups. Hierarchical clustering showed that blinded duplicates were correctly identified as the closest related samples. hESC lines clustered together irrespective of the laboratory in which they were maintained. hESCs could be readily distinguished from embryoid bodies (EB) differentiated from them and the karyotypically abnormal hESC line BG01V. The embryonal carcinoma (EC) line NTera2 is a useful model for evaluating characteristics of hESCs. Expression of subsets of individual genes was validated by comparing with published databases, MPSS (Massively Parallel Signature Sequencing) libraries, and parallel analysis by microarray and RT-PCR. CONCLUSION: we show that Illumina's bead array platform is a reliable, reproducible and robust method for developing base global profiles of cells and identifying similarities and differences in large number of samples.

Carcinoma, Embryonal↗

PubMed2006

Transcriptome coexpression map of human embryonic stem cells.

BACKGROUND: Human embryonic stem (ES) cells hold great promise for medicine and science. The transcriptome of human ES cells has been studied in detail in recent years. However, no systematic analysis has yet addressed whether gene expression in human ES cells may be regulated in chromosomal domains, and no chromosomal domains of coexpression have been identified. RESULTS: We report the first transcriptome coexpression map of the human ES cell and the earliest stage of ES differentiation, the embryoid body (EB), for the analysis of how transcriptional regulation interacts with genomic structure during ES self-renewal and differentiation. We determined the gene expression profiles from multiple ES and EB samples and identified chromosomal domains showing coexpression of adjacent genes on the genome. The coexpression domains were not random, with significant enrichment in chromosomes 8, 11, 16, 17, 19, and Y in the ES state, and 6, 11, 17, 19 and 20 in the EB state. The domains were significantly associated with Giemsa-negative bands in EB, yet showed little correlation with known cytogenetic structures in ES cells. Different patterns of coexpression were revealed by comparative transcriptome mapping between ES and EB. CONCLUSION: The findings and methods reported in this investigation advance our understanding of how genome organization affects gene expression in human ES cells and help to identify new mechanisms and pathways controlling ES self-renewal or differentiation.

Animals↗

PubMed2006

Stress-induced plasticity of monoamine axons.

Central serotonergic (5-HT) and noradrenergic (NA) neurons, which innervate the same regions of the brain, are known to play a crucial role in emotion and mood. These monoamine neurons have a great capacity to alter axonal morphology in response to repeated stress. The morphological responses of 5-HT and NA axons to repeated stress are different, and they sometimes even demonstrate opposite responses (namely, either sprouting or degeneration). Moreover, a morphological interaction also occurs between 5-HT and NA axons during axonal regeneration. This review describes the differential features of axonal plasticity of 5-HT and NA neurons in relation to stress, and discusses the possible roles that the morphological plasticity of 5-HT and NA axons may play in the pathophysiology of depression.

Amines↗

PubMed2006

[Survey of plasma lipid value in children in Beijing area and the changes of gaseous molecule-hydrogen sulfide in the ones with dyslipidemia].

OBJECTIVE: To evaluate plasma lipid value in children in Beijing areas and to explore the relationship between plasma hydrogen sulfide (H(2)S) level and lipid components. METHODS: A total of 971 healthy school students were chosen randomly, all coming from Beijing city and its counties. They were divided into four groups according to their gender and age (boys and girls in school age and in puberty). Body mass index (BMI) was calculated according to the measurement of body height and weight. Familial history, past medical history and the history of present illness were investigated. Physical examination was also carried on. Alanine aminotransferase (ALT), total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C) were detected by HITACHI 7060 automatic biochemical analyzer. Forty children (31 males and 9 females) with dyslipidemia were chosen randomly among them as patients. Other 60 children (38 males and 22 females) with normal plasma lipid level served as controls. Plasma H(2)S level was detected by modified sulfide electrode. RESULTS: There were 91 children with dyslipidemia (58 males and 33 females) in 971 students. The prevalence rate was 9.37%. The average value of BMI in patients was higher than that of controls. An association of increased ALT level with the prevalence of dyslipidemia was observed. Hydrogen sulfide concentration in plasma showed out skew distribution. Measurement data were presented as median (P(25), P(75)). Hydrogen sulfide was 34.40 (32.98, 35.47) micromol/L in children with dyslipidemia and 38.81(36.53, 40.66) micromol/L in controls. There was statistical difference between the two groups (P<0.01). Average value of plasma hydrogen sulfide was 35.54 (33.41, 39.24) micromol/L in males and 37.82 (33.84, 39.80) micromol/L in females. There was no difference in plasma hydrogen sulfide between male and female subjects (P>0.05). CONCLUSION: The prevalence rate of dyslipidemia in Beijing children is relatively high as compared with what it was during the past several decades. There was a significant decrease in plasma endogenous H(2)S level in children with dyslipidemia as compared with that of healthy children. There was an obvious correlation between plasma hydrogen sulfide and plasma lipids.

Adolescent↗

PubMed2006

Combined array-comparative genomic hybridization and single-nucleotide polymorphism-loss of heterozygosity analysis reveals complex changes and multiple forms of chromosomal instability in colorectal cancers.

Cancers with chromosomal instability (CIN) are held to be aneuploid/polyploid with multiple large-scale gains/deletions, but the processes underlying CIN are unclear and different types of CIN might exist. We investigated colorectal cancer cell lines using array-comparative genomic hybridization (CGH) for copy number changes and single-copy number polymorphism (SNP) microarrays for allelic loss (LOH). Many array-based CGH changes were not found by LOH because they did not cause true reduction-to-homozygosity. Conversely, many regions of SNP-LOH occurred in the absence of copy number change, comprising an average per cell line of 2 chromosomes with complete LOH; 1-2 terminal regions of LOH (mitotic recombination); and 1 interstitial region of LOH. SNP-LOH detected many novel changes, representing possible locations of uncharacterized tumor suppressor loci. Microsatellite unstable (MSI+) lines infrequently showed gains/deletions or whole-chromosome LOH, but their near-diploid karyotypes concealed mitotic recombination frequencies similar to those of MSI- lines. We analyzed p53 and chromosome 18q (SMAD4) in detail, including mutation screening. Almost all MSI- lines showed LOH and/or deletion of p53 and 18q; some near-triploid lines had acquired three independent changes at these loci. We found consistent results in primary colorectal cancers. Overall, the distributions of mitotic recombination and whole-chromosome LOH in the MSI- cell lines differed significantly from random, with some lines having much higher than expected levels of these changes. Moreover, lines with more LOH changes had significantly fewer copy number changes. These data suggest that CIN is not synonymous with copy number change and some cancers have a specific tendency to whole-chromosome deletion and regain or to mitotic recombination.

Cell Line, Tumor↗

PubMed2006

Influence of the third-order parameter on diffuse reflectance at small source-detector separations.

Spatially resolved reflectance close to source has received a great deal of attention recently. This research is considered to develop a new noninvasive technique for measuring the optical properties of biological media. Using Monte Carlo simulations, we investigated the influence of third-order parameter 5 on diffuse reflectance and found that the reflectance decreased with an increase of delta at a short source-detector separation of approximately 0.7-2 transport mean free paths. We show that the effects of two parameters, y and second-order parameter delta, on the reflectance are contrary. As a result the influence of the second-order parameter y on the reflectance is irregular when the condition delta delta<<delta gamma is not satisfied.

Algorithms↗

PubMed2006

Only one protomer is active in the dimer of SARS 3C-like proteinase.

The severe acute respiratory syndrome coronavirus 3C-like protease has been proposed to be a key target for structurally based drug design against SARS. The enzyme exists as a mixture of dimer and monomer, and only the dimer was considered to be active. In this report, we have investigated, using molecular dynamics simulation and mutational studies, the problems as to why only the dimer is active and whether both of the two protomers in the dimer are active. The molecular dynamics simulations show that the monomers are always inactive, that the two protomers in the dimer are asymmetric, and that only one protomer is active at a time. The enzyme activity of the hybrid severe acute respiratory syndrome coronavirus 3C-like protease of the wild-type protein and the inactive mutant proves that the dimerization is important for enzyme activity and only one active protomer in the dimer is enough for the catalysis. Our simulations also show that the right conformation for catalysis in one protomer can be induced upon dimer formation. These results suggest that the enzyme may follow the association, activation, catalysis, and dissociation mechanism for activity control.

Binding Sites↗

PubMed2006

Suppression of Fas-FasL coexpression by erythropoietin mediates erythroblast expansion during the erythropoietic stress response in vivo.

Erythropoietin (Epo) is the principal regulator of the erythropoietic response to hypoxic stress, through its receptor, EpoR. The EpoR signals mediating the stress response are largely unknown, and the spectrum of progenitors that are stress responsive is not fully defined. Here, we used flow cytometry to identify stress-responsive Ter119+CD71highFSChigh early erythroblast subsets in vivo. In the mouse spleen, an erythropoietic reserve organ, early erythroblasts were present at lower frequencies and were undergoing higher rates of apoptosis than equivalent cells in bone marrow. A high proportion of splenic early erythroblasts coexpressed the death receptor Fas, and its ligand, FasL. Fas-positive early erythroblasts were significantly more likely to coexpress annexin V than equivalent, Fas-negative cells, suggesting that Fas mediates early erythroblast apoptosis in vivo. We examined several mouse models of erythropoietic stress, including erythrocytosis and beta-thalassemia. We found a dramatic increase in the frequency of splenic early erythroblasts that correlated with down-regulation of Fas and FasL from their cell surface. Further, a single injection of Epo specifically suppressed early erythroblast Fas and FasL mRNA and cell-surface expression. Therefore, Fas and FasL are negative regulators of erythropoiesis. Epo-mediated suppression of erythroblast Fas and FasL is a novel stress response pathway that facilitates erythroblast expansion in vivo.

Animals↗

PubMed2006

Preparation and characteristics of high pH-resistant sol-gel alumina-based hybrid organic-inorganic coating for solid-phase microextraction of polar compounds.

A novel alumina-based hybrid organic-inorganic sol-gel coating was first developed for solid-phase microextraction (SPME) from a highly reactive alkoxide precursor, aluminum sec-butoxide, and a sol-gel-active organic polymer hydroxyl-terminated polydimethylsiloxane (OH-TSO). The underlying mechanism was discussed and confirmed by IR spectra. The porous surface structure of the sol-gel coating was revealed by scanning electron microscopy. A detailed investigation was conducted to evaluate the remarked performance of the newly developed sol-gel alumina-OH-TSO hybrid materials. In stark contrast to the sol-gel silica-based coating, the alumina-based coating demonstrated excellent pH stability. In addition, good thermal resistance and coating preparation reproducibility are also its outstanding performance. As compared to silica-based hybrids material, the ligand exchange ability of alumina makes it structurally superior extraction sorbents for polar compounds, such as fatty acids, phenols, alcohols, aldehydes and amines. Practical applicability of the prepared alumina-OH-TSO fiber was demonstrated through the analysis of volatile alcohols and fatty acids in beer. The recoveries obtained ranged from 85.7 to 104% and the relative standard deviation values for all analytes were below 9%.

Aluminum Oxide↗

PubMed2006

Localization of putative stem cells and four cell populations with different differentiation degree in mouse mammary anlagen.

The precise localization of putative stem cells and other cells within the embryonic mammary gland would help to elucidate the molecular pathways that govern normal mammary development. The ultrastructural appearances and the antigen of Sca-1 were considered together as putative stem cell markers, and the antigens of cytokeratin, CD10, Muc-1 and CD34 as differentiation markers. Electron microscopy was performed to reveal the ultrastructure of cells in different site of the mammary anlagen. An immunofluorescence system was used to reveal the whole structure profile of the mammary anlagen using the anti-cytokeratin antibody to localize specific types of cell populations such as Sca-1, CD10, Muc-1 and CD34 positive cells within the anlagen, which distribute near the inside edge, distribute uniformly, distribute in the central region and distribute in the site of mesenchyme around the neck of the anlagen, respectively. We also observed under electron microscope that some pale cells like putative stem cells reported by prevenient scholars, which are mainly distributed in the Sca-1(+) cell population near the inside edge of the anlagen, have pale-stained nucleoplasm and cytoplasm, sparse organelles clustered close to their nucleus and have a lack of rough endoplasmic reticulums and cell polarization. The results indicate that the putative stem cells are localized near the edge of the mammary anlagen; the cell populations with different differentiation degree were localized in the central part and around the edge within the anlagen.

Animals↗

PubMed2006

A continuous fluorescence assay for phospholipase A2 with nontagged lipid.

Human nonpancreatic secreted phospholipase A2 (hnps PLA2) is considered to be an important drug target for antiinflammation therapy. We have established a new fluorescence assay by using 1-anilinonaphthalene-8-sulfonate (ANS) as an interfacial probe for hydrophobic environment detection. The fitted apparent k(cat)/K(m) of hnps PLA2 is 0.0181 +/- 0.0005 RFU/microMs. Tests on known synthesized inhibitor gave IC50 values similar to those from isotope-labeled assay. Because ANS is a commonly used probe for hydrophobic environment detection that needs no modification in the current assay, this strategy may be widely applicable for interfacial catalytic reactions.

Anilino Naphthalenesulfonates↗

PubMed2006

Thyroid hormone action at the cellular, genomic and target gene levels.

Thyroid hormone (TH) plays important roles in metabolism, growth and differentiation. Thyroid hormone receptors (TRs) are ligand-regulatable transcription factors that bind both TH and DNA enhancer sequences in the promoter region of target genes where they can interact with co-repressor and co-activator complexes. These interactons, in turn, have consequent effects on transcription. This review describes studies on TH action from our laboratory examining the cellular localization and motility of TRs using green fluorescent fusion proteins, gene expression profiles of TH in WT and TRalpha and TRbeta KO mice, as well as general transcription factor and co-activator recruitment on the promoters of target genes by TH in chromatin immunoprecipitation assays.

Animals↗

PubMed2006

Fabrication of three-dimensional photonic crystals with two-beam holographic lithography.

A holographic technique used to fabricate three-dimensional photonic crystals with a two-beam interference method is presented. In the optical setup of fabrication one beam is incident on the recording plate in the direction of the plate normal and the other beam with an angle to the normal. Three exposures were taken. Between each exposure, the recording plate was rotated 120 degrees on axis until three exposures were completed. Good three-dimensional lattice structures have been obtained. Theoretical analysis, computer simulations, and experimental results are presented.

Journal Article↗

PubMed2006

Analysis of P53 mutations and their expression in 56 colorectal cancer cell lines.

A comprehensive analysis of the TP53 gene and its protein status was carried out on a panel of 56 colorectal cancer cell lines. This analysis was based on a combination of denaturing HPLC mutation screening of all exons of the p53 gene, sequencing the cDNA, and assessing the function of the p53 protein by assaying the induced expression of phosphorylated p53 and p21 after exposing cells to gamma-rays. In a few cases where there was no production of p53 message nor evidence of functional p53 protein, all of the p53 exons were sequenced directly. Thirteen of the 56 cell lines had functional p53, 21 lines had missense mutations (one of which made no detectable protein), 4 lines produced no p53 transcripts, and the remaining 18 lines carried truncating TP53 mutations. Thus, our results showed a relatively high frequency of TP53 mutations (76.8%) in our cell lines, with almost half of the mutations being truncating mutations. This is a rather higher frequency of such mutations than usually reported. Of the 18 cell lines with truncating mutations, 12 had detectable truncated protein based on Western blot analysis, whereas no protein was detected in the remaining 6 cell lines. Our data provide a valuable source of TP 53 mutations for further studies and raise the question of the extent to which truncating mutations may have dominant negative effects, even when no truncated protein can be detected by standard methods.

Alternative Splicing↗

PubMed2006

[Clinical diagnosis and surgical treatment of primary pulmonary lymphoma].

OBJECTIVE: To study the clinical characteristics, the principles of diagnosis and surgical treatment for primary pulmonary lymphoma. METHOD: Ten patients with primary pulmonary lymphoma were treated surgically and their clinical characteristics, the experiences of clinical diagnosis and surgical treatment were analyzed. The tumors located in left upper lobe in 2, left lower lobe in 1, right upper lobe in 3, right middle lobe in 3 and right lower lobe in 1. The main symptoms were cough and (or) hemoptysis. Imageological representations (X-ray and CT scanning of thorax) were similar to primary pulmonary carcinoma. Broncho-fibroscopic examination was performed on all cases with negative findings. Eight cases were mistakenly diagnosed as primary pulmonary carcinoma by imageological representations. Only 2 cases were diagnosed as primary pulmonary lymphoma by percutaneous needle biopsy and pathologic examination. All cases received pneumonectomy, ipsilateral hilar and mediastinal lymphadenectomy. All cases with non-Hodgkin's lymphoma received regular chemotherapy (MOPP and ABVD scheme for 1 case with Hodgkin's disease respectively, CHOP for 8 cases with non-Hodgkin's lymphoma), and 3 cases received radiotherapy postoperatively. RESULTS: Eight cases were non-Hodgkin's lymphoma (B-type) and 2 cases were Hodgkin's disease (mixed type) confirmed by pathological examination. Six cases with non-Hodgkin's lymphoma (3 cases for stage IE, 2 cases for stage II 1E, and 1 case for stage II 2E W) had been surviving for 18-42 months until the follow-up. Two cases with non-Hodgkin's lymphoma (stage II 2E, B-cell, low-grade) and 2 cases with Hodgkin's disease (stage IE and II 2E, mixed type) died in 24, 32, 8 and 17 months postoperatively respectively. CONCLUSIONS: Primary pulmonary lymphoma is a rare type of malignant lung neoplasm without special clinical features. The preoperative diagnosis is difficult. Treatment modalities include surgical treatment, radiotherapy and regular chemotherapy postoperatively.

Adult↗

PubMed2006

Speckle photography: mixed domain fractional Fourier motion detection.

A reflection-based optical implementation of two simultaneous scale-invariant fractional Fourier transforms (FRTs) is used to develop a novel compact speckle photographic system. The system allows the independent determination of both surface tilting and in-plane translational motion from two sequential mixed domain images captured using a single camera.

Journal Article↗