PubMed Health⌕ Search

Biomedical subjects

Ying Liu

Publications and source records attributed to Ying Liu.

At least 415 records · Page 23Linked to original sources
PubMed2002

Physical and transcript map of the region between D6S264 and D6S149 on chromosome 6q27, the minimal region of allele loss in sporadic epithelial ovarian cancer.

We have previously shown a high frequency of allele loss at D6S193 (62%) on chromosomal arm 6q27 in ovarian tumours and mapped the minimal region of allele loss between D6S297 and D6S264 (3 cM). We isolated and mapped a single non-chimaeric YAC (17IA12, 260-280 kb) containing D6S193 and D6S297. A further extended bacterial contig (between D6S264 and D6S149) has been established using PACs and BACs and a transcript map has been established. We have mapped six new markers to the YAC; three of them are ESTs (WI-15078, WI-8751, and TCP10). We have isolated three cDNA clones of EST WI-15078 and one clone contains a complete open reading frame. The sequence shows homology to a new member of the ribonuclease family. The other two clones are splice variants of this new gene. The gene is expressed ubiquitously in normal tissues. It is expressed in 4/8 ovarian cancer cell lines by Northern analysis. The gene encodes for a 40 kDa protein. Direct sequencing of the gene in all the eight ovarian cancer cell lines did not identify any mutations. Clonogenic assays were performed by transfecting the full-length gene in to ovarian cancer cell lines and no suppression of growth was observed.

Amino Acid Sequence↗
PubMed2002

Enantioseparation of chiral sulfoxides and sulfinate esters by capillary electrophoresis.

Forty-one chiral sulfoxides and sulfinate esters were separated using sulfated beta-cyclodextrin and carboxymethyl beta-cyclodextrin as chiral selectors. Binding constants of some analytes to both chiral selectors were measured in order to examine and help explain the observed migration behavior and enantioselectivity trends. Overall, sulfated beta-cyclodextrin separated a greater number of compounds, and had better separating capabilities than did carboxymethyl beta-cyclodextrin for these analytes. This was true even though all of the analytes showed much stronger binding to carboxymethyl beta-cyclodextrin than to sulfated beta-cyclodextrin. General procedures to optimize the separation, by varying pH, selector concentration, and organic modifier concentration were examined and discussed. Chiral selector concentration had the greatest effect on enantioseparation, with higher concentrations of selector giving better peak-to-peak separations. Organic modifier had an adverse affect on resolution, with increasing amounts giving lower mobility differences. Lastly, pH had only a minimal effect on separation.

Cyclodextrins↗
PubMed2002

A unified framework for transmission-disequilibrium test analysis of discrete and continuous traits.

This paper presents a unified framework for transmission-disequilibrium tests for discrete and continuous traits. A conditional score test is derived that maximizes power to detect small effects for any exponential family distribution, which includes binary and normal distributions, and distributions that are skewed or have non-normal kurtosis. The specific distributional form need not be specified, and the method applies to sibships of arbitrary size. Formulas for the distribution of the test statistic are given for models including complex genetic effects (additive, dominant, and recessive gene action), covariates, multiple gene models including gene-gene interactions or heterogeneity, and gene-environment interactions. We develop refinements of our method for trait-based sampling designs and multiple siblings that can have dramatic effects on power.

Alleles↗
PubMed2002

Oligodendrocyte and astrocyte development in rodents: an in situ and immunohistological analysis during embryonic development.

Lineally related multipotent neuroepithelial cells (NEP), neuronal restricted precursors (NRP), and glial restricted precursors (GRP) have been identified in the spinal cord. To determine the sequence of differentiation and identify lineage and stage-specific markers, we have examined the spatiotemporal expression of established glial markers during rodent embryonic development and within fetal cell culture. In this report, we show that proliferating stem cells in the developing neural tube do not express any glial markers at E10.5. By E11, however, glial precursors have begun to differentiate and at least two regions of the ventral neural tube containing glial precursor cells can be distinguished, an Nkx2.2/Neurogenin 3 (Ngn3) domain and a platelet-derived growth factor receptor alpha (PDGFRalpha)/Olig2/Sox10 domain. Radial glia, as identified by RC1 immunoreactivity, develop in concert with other glial precursors and can be distinguished by their morphology, spatial distribution, and antigen expression. Astrocytes as assessed by glial fibrillary acidic protein (GFAP) immunoreactivity are first detected at E16. A novel dorsal domain of CD44 immunoreactivity that can be distinguished from the more ventral glial precursor domains can be detected as early as E13.5.

Animals↗
PubMed2002

Microarray analysis of selected genes in neural stem and progenitor cells.

To access and compare gene expression in fetal neuroepithelial cells (NEPs) and progenitor cells, we have used microarrays containing approximately 500 known genes related to cell cycle regulation, apoptosis, growth and differentiation. We have identified 152 genes that are expressed in NEPs and 209 genes expressed by progenitor cells. The majority of genes (141) detected in NEPs are also present in progenitor populations. There are 68 genes specifically expressed in progenitors with little or no expression in NEPs, and a few genes that appear to be present exclusively in NEPs. Using cell sorting, RT-PCR, in situ hybridization or immunocytochemistry, we have examined the segregation of expression to neuronal and glial progenitors, and identified several that appeared to be enriched in neuronal (e.g. CDK5, neuropilin, EphrinB2, FGF11) or glial (e.g. CXCR4, RhoC, CD44, tenascin C) precursors. Our data provide a first report of gene expression profiles of neural stem and progenitor cells at early stages of development, and provide evidence for the potential roles of specific cell cycle regulators, chemokines, cytokines and extracellular matrix molecules in neural development and lineage segregation.

Animals↗
PubMed2002

Direct participation of Sam68, the 68-kilodalton Src-associated protein in mitosis, in the CRM1-mediated Rev nuclear export pathway.

Human immunodeficiency virus type 1 (HIV-1) replication requires efficient nuclear export of incompletely spliced and unspliced HIV-1 mRNA transcripts, which is achieved by Rev expression at an early stage of the viral life cycle. We have recently shown that expression of Sam68, the 68-kDa Src-associated protein in mitosis, is able to alleviate Rev function block in astrocytes by promoting Rev nuclear export. In the present study, we utilized an antisense RNA expression strategy to down-modulate constitutive Sam68 expression and examined its effect on Rev function, HIV-1 gene expression, and viral replication. These results showed that down-modulation of constitutive Sam68 expression markedly inhibited HIV-1 production in 293T cells and viral replication in T lymphocytes such as Jurkat and CEM cells, as well as human peripheral blood mononuclear cells (PBMCs). Rev-dependent in trans complementation and reporter gene assays further demonstrated that inhibition of HIV-1 gene expression by Sam68 down-modulation was due to impeded Rev activity. Moreover, digital fluorescence microscopic imaging revealed that down-modulation of Sam68 expression caused exclusive nuclear retention and colocalization of both Rev and CRM1. Taken together, these data suggest that adequate Sam68 expression is required for Rev function and, thereby, for HIV-1 gene expression and viral replication, and they support the notion that Sam68 is directly involved in the CRM1-mediated Rev nuclear export pathway.

Active Transport, Cell Nucleus↗
PubMed2002

Expression of exogenous Sam68, the 68-kilodalton SRC-associated protein in mitosis, is able to alleviate impaired Rev function in astrocytes.

Human immunodeficiency virus type 1 (HIV-1) gene expression in astrocytes is restricted, resulting in a brief and limited synthesis of HIV-1 viral structural proteins. Impaired Rev function has been documented in these cells. However, the molecular mechanisms underlying the impaired Rev function are not fully understood. Using the astroglial cell line U87.MG as a model, we report here that HIV-1 gene expression down-regulated expression of Sam68, the 68-kDa Src-associated protein in mitosis, which was constitutively expressed at a lower level in astrocytes. Elevating the endogenous level of Sam68 expression considerably restored HIV-1 Rev function in astrocytes, as determined by a Rev-dependent reporter gene assay. However, elevation of Sam68 expression achieved only a modest increase in HIV-1 production, further supporting the notion that there are multiple cellular restrictions of HIV-1 gene expression in astrocytes. Mutagenesis analysis identified the region between amino acids 321 and 410 of Sam68 as being directly involved in the binding of Sam68 to Rev, while a double mutation in Rev, L78D and E79L, like those in the dominant-negative Rev mutant M10, eliminated Rev binding to Sam68. Moreover, subcellular fractionation and digital fluorescence microscopic imaging revealed that Sam68 expression promoted Rev nuclear export. Taken together, our studies demonstrate that a lower level of constitutive Sam68 expression, followed by further down-regulation by HIV-1 infection, contributes to impaired Rev function in astrocytes, and they suggest that Sam68 may play an important role in Rev nuclear export.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Ca(2+)/calmodulin-dependent and cAMP-dependent kinases in induction of c-fos in human mesangial cells.

Mesangial cell proliferation is an early event in several progressive renal diseases. When mesangial cells in culture are rendered quiescent by serum starvation and subsequently stimulated to proliferate, induction of c-fos is an early indicator of entry into the cell cycle. Several heparin-sensitive signals transduce these events. We have examined the potential roles of CaMK and PKA. Selective stimulation of CaMK with Ca(2+) ionophores and of PKA with forskolin or dibutyryl cAMP both result in induction of c-fos mRNA. CaMK but not PKA signaling is suppressed by low concentrations of heparin. Cross talk between the pathways has been demonstrated in some cells, with evidence of CaMK phosphorylating cAMP response element binding protein (CREB) at an inhibitory site and PKA suppressing CaMK-dependent signaling. However, in the present study, both pathways phosphorylated CREB on Ser(133) and induced c-fos in an additive manner. Serum, ionomycin, and forskolin all caused a rapid decline in cyclin D1 levels, but only serum effected a subsequent increase, indicative of cell cycle progression. We conclude that, in human mesangial cells, CaMK and PKA can both contribute to cell cycle entry, and, although induction of c-fos by CaMK requires active PKA, neither pathway antagonizes or synergizes c-fos induction by the other.

Anticoagulants↗
PubMed2002

Relation between type A behavior pattern and the extent of coronary atherosclerosis in Japanese women.

This study examined the relation of Type A behavior pattern and its components to angiographically documented coronary atherosclerosis in 198 Japanese women. A questionnaire-based interview elicited psychosocial and other factors. Type A behavior pattern was measured by 12 questions. Significant coronary stenosis was defined when a 75% or greater luminal narrowing occurred at one or more major coronary arteries or 50% or greater narrowing occurred at the left main artery. Gensini's score also was calculated. Logistic regression analysis was used to calculate odds ratios and 95% confidence intervals with adjustment for traditional coronary risk factors and the presence of a job. Global Type A behavior pattern showed no material association with the severity of coronary atherosclerosis assessed by both Gensini's score and the presence of significant coronary stenosis. However, its subcomponents, enthusiasm and competitiveness, were positively related to the severity of coronary atherosclerosis, whereas self-confidence and perfectionism were negatively related. These findings suggest overall a null association between global Type A and coronary atherosclerosis as well as the presence of toxic or beneficial components of Type A behaviors in Japanese women.

Aged↗
PubMed2002

Growth arrest specific gene 1 acts as a region-specific mediator of the Fgf10/Fgf8 regulatory loop in the limb.

Proximal-to-distal growth of the embryonic limbs requires Fgf10 in the mesenchyme to activate Fgf8 in the apical ectodermal ridge (AER), which in turn promotes mesenchymal outgrowth. We show here that the growth arrest specific gene 1 (Gas1) is required in the mesenchyme for the normal regulation of Fgf10/Fgf8. Gas1 mutant limbs have defects in the proliferation of the AER and the mesenchyme and develop with small autopods, missing phalanges and anterior digit syndactyly. At the molecular level, Fgf10 expression at the distal tip mesenchyme immediately underneath the AER is preferentially affected in the mutant limb, coinciding with the loss of Fgf8 expression in the AER. To test whether FGF10 deficiency is an underlying cause of the Gas1 mutant phenotype, we employed a limb culture system in conjunction with microinjection of recombinant proteins. In this system, FGF10 but not FGF8 protein injected into the mutant distal tip mesenchyme restores Fgf8 expression in the AER. Our data provide evidence that Gas1 acts to maintain high levels of FGF10 at the tip mesenchyme and support the proposal that Fgf10 expression in this region is crucial for maintaining Fgf8 expression in the AER.

Animals↗
PubMed2002

A1166C polymorphism of the angiotensin II type 1 receptor gene and essential hypertension in Han, Tibetan and Yi populations.

Our aim was to clarify whether substitution of cytosine for adenine at position 1166 (A1166C) polymorphism of the angiotensin II type 1 receptor (AT1R) gene is associated with susceptibility to essential hypertension in Han, Tibetan and Yi populations in China. This study involved 302 normotensive and 446 hypertensive subjects. The polymorphism was detected by polymelase chain reaction of genomic DNA and restriction fragment length polymorphism (PCR-RFLP) in genomic DNA. The data were analyzed by analysis of covariance (ANCOVA), X2 test, and multiple logistic regression. In normotensive controls, the A1166 allele frequencies were 0.979, 0.939 and 0.965 in Han, Tibetan and Yi participants, respectively. There was no significant intergroup variation in frequency of the allele in normotensives (X2=4.166, p=0.125). The frequency of the A1166 allele was significantly higher in Tibetan male hypertensives than that in normotensives (X2=11.46, p=0.001). There was no significant difference in A1166C genotype distribution and allele frequency between normotensives and hypertensives either in the Han (p=0.465) or Yi (p=0.357) populations. Body mass index in the Han and Yi populations (p=0.0001), age in the Tibetan and Yi populations (p=0.0001), and AA genotype in the Tibetan male population (p=0.0034) all were independent risk factors for hypertension. Diastolic blood pressure levels were significantly higher in Tibetan male subjects with the AA genotype than in those with the AC+CC genotype (p=0.0040). We concluded that the A1166 allele is very common in Han, Tibetan and Yi populations, approximately 1.35-fold more common than in Caucasians. The A1166 allele of the AT1R gene may be a predisposing factor for essential hypertension in Tibetan males. A1166C polymorphism of the AT1R gene is probably not involved in the pathogenesis of essential hypertension in Han or Yi populations.

Adult↗
PubMed2002

Tumour suppressor genes in sporadic epithelial ovarian cancer.

Ovarian cancer is the most frequent cause of death from gynaecological malignancies in the western world, and sporadic epithelial ovarian cancer is its most predominant form. The aetiology of sporadic ovarian cancer remains unknown. Genetic studies have enabled a better understanding of the evolution of tumour progression. A major focus of research has been to identify tumour suppressor genes implicated in sporadic ovarian cancer over the past decade. Several tumour suppressor genes have been identified by strategies such as positional cloning and differential expression display. Further research is warranted to understand fully their contribution to the pathogenesis of sporadic ovarian cancer.

BRCA1 Protein↗
PubMed2002

Novel characterization of MHC class II-negative population of resident corneal Langerhans cell-type dendritic cells.

PURPOSE: The presence of antigen-presenting cells (APCs) such as Langerhans cells (LCs), an epithelial form of dendritic cells (DCs), in corneal tissue is critical for generation of immune responses, including graft rejection and herpetic keratitis. The purpose of this study was to characterize the distribution and major histocompatibility complex (MHC) antigen expression of corneal LCs. METHODS: Normal and inflamed corneas were excised from BALB/c mice, and immunofluorescence staining for CD11c, CD11b, CD45, CD80 (B7.1), CD86 (B7.2), CD3, and MHC class II (Ia) was performed by confocal microscopy on wholemount corneal epithelium. RESULTS: CD11c(+) MHC class II-positive LCs were found in the limbus and corneal periphery, but not in the center of the normal cornea. These cells were CD45 positive, exhibiting bone marrow derivation, and CD3 and CD11b negative, confirming a DC lineage. Additionally, these cells were CD80 and CD86 negative, reflecting an immature phenotype. In the central and paracentral areas, however, significant numbers of CD11c(+) LCs were detected that expressed no MHC class II. It is important to note that although the density of the LCs declined from the limbus toward the center of the cornea, they were always present. In the inflamed cornea, the expression of MHC class II and costimulatory molecules CD80 and CD86 was significantly enhanced, and present in all parts of the cornea, in contrast to the normal cornea. CONCLUSIONS: The present study demonstrates for the first time the phenotype and distribution of MHC class II-negative LCs in the murine corneal epithelium. In the inflamed cornea, the LCs become activated as reflected by expression of B7 costimulatory markers. These changes in activation markers may provide additional information for devising novel immunomodulatory strategies.

Animals↗
PubMed2002

[Teratosis and damage of viscera induced by microcystin in SD rat fetuses].

OBJECTIVE: To study the teratogenicity and traumatic effect of microcystin LR (MCLR) on pregnant SD rats and their fetuses. METHODS: Sixty pregnant SD rats were divided into four groups, 16 in each group: three experimental groups in which MCLR was injected into the abdominal cavity at the doses of 4 microgram/kg, 16 microgram/kg, and 62 microgram/kg respectively for 10 days, and control group injected with normal saline. Twenty days after, the pregnant rats were killed. The development, teratosis, and histology of viscera of the fetuses were examined. RESULTS: Deformities were found in the fetuses of the 62 microgram/kg group and 16 microgram/kg group with the teratogenic rate of 11.70 per thousand (2/172) and 6.76 per thousand (1/155). Petechial hemorrhage and severe hydropic degeneration in liver and maldevelopment of glomeruli and renal medulla were found in 62 microgram/kg group. Mild granular degeneration was found in the liver of fetuses in 4 microgram/kg group. CONCLUSION: MCLR passes through the placental barrier and causes damage in kidney and liver, which may be the basis of high incidence of liver cancer microgram in the fetus phase.

Animals↗
PubMed2002

[The dose-response relationship study between the quantitative morphological stereology on thyroid and different iodine doses in mice].

OBJECTIVE: To study the dose-response relationship between the quantitative morphological stereology on thyroid and different iodine doses in mice. METHODS: Weaning Kunming mice were randomly divided into seven groups. The mice were fed for 100 days with distilled water containing different KIO3 concentrations, i.e. 50, 250, 500, 1 000, 1 500, 2 000, and 3 000 microgram/L respectively. The 50 microgram/L (proper iodine concentration) group was control group, and the groups of 250 approximately 3 000 microgram/L were high iodine groups. The stereology parameters of thyroid follicle and follicular cavities were measured with HPIAS-1000 (High Resolution Pathological Image & word Analysis System). The stereology parameters included mean surface, volume on area, volume on circumference, specific surface, numerical density on area, spherical factor, the percentage of mean surface and mean volume of the follicular epithelial cell in thyroid follicle was further calculated. RESULTS: Positive correlations was observed between the thyroid absolute and relative weight, goiter rate and different iodine doses. And the thyroid absolute and relative weight of mice in the 250 microgram/L group was significantly different from that in 50 microgram/L group. The goiter rate of mice in different high iodine groups was in conformity with that of epidemiological investigation. The goiter rate of mice in 500 microgram/L group was different from that in 50 microgram/L group. Positive correlations were observed between mean surface, volume on area, volume on circumference, spherical factor and iodine doses, but the negative correlations were observed between numerical density on area, specific surface, the percentage of mean surface and mean volume of the follicular epithelial cell in thyroid follicle and iodine doses. CONCLUSIONS: When Iodine doses are between 250 approximately 3 000 microgram/L, the dose-response relationship was observed between the morphological stereology parameters of thyroid follicle and follicular cavities and iodine doses, and when the dose of iodine is 250 microgram/L, it is possible to induce colloid goiter of mice. The goiter rates of mice resulted by different high iodine doses were in conformity with that of the epidemiological investigation of people.

Animals↗
PubMed2002

[Analysis on competition and coexistence patterns of Aneurolepidium chinense and its main companion species].

In this study, transects were set in areas where Aneurolepidium chinense and its companion species grew together. Competition and coexistence patterns of these species in the ecotone were analyzed using the following measures:frequency distribution, spatial pattern, and pattern intensity. Patterns of A. chinense and its main companion species were diverse. Aggregation was the tactics for A. chinense to defend the foreign species' invading or disperse itself. There existed competition and coexistence between A. chinense and its main companion species. A. chinense and Phragmite communis competed and coexisted through suppression. A. chinense and Kalimeris interifolia coexisted through competition. Hierochloe glabra and Puccinellia tenuiflora competed with A. chinense through clonal growth. Calamagrostis epigeios was suppressed by A. chinense.

China↗
PubMed2002

[Quantification of metallothionein induced with selenium by using competitive ELISA].

Metallothionein induced by selenium was assayed with competitive ELISA. It was found that in control mice, the liver contained (2.47+/-0.90) microgram MT/g wet weight tissue, while the mice administered with ZnSO(4) contained (8.15+/-2.20) microgram MT/g wet weight liver tissue and the mice given with selenium malt contained (12.80+/-1.44) microgram MT/g wet weight liver. A significant difference was found between the control and the latter two groups (P<0.05, P<0.05). The MT content of selenium group was significantly higher than the zinc group. It is suggested that the selenium was more potent in induction of MT and was a stronger inducer than ZnSO(4) in its effective dose range, therefore selenium may be developed into a novel and safe MT inducer.

Animals↗