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Biomedical subjects

Lin Liu

Publications and source records attributed to Lin Liu.

At least 73 records · Page 4Linked to original sources
PubMed2005

Crystal structure of human B-type phosphoglycerate mutase bound with citrate.

The B-type cofactor-dependent phosphoglycerate mutase (dPGM-B) catalyzes the interconversion of 2-phosphoglycerate and 3-phosphoglycerate in glycolysis and gluconeogenesis pathways using 2,3-bisphosphoglycerate as the cofactor. The crystal structures of human dPGM-B bound with citrate were determined in two crystal forms. These structures reveal a dimerization mode conserved in both of dPGM and BPGM (bisphosphoglycerate mutase), based on which a dPGM/BPGM heterodimer structure is proposed. Structural comparison supports that the conformational changes of residues 13-21 and 98-117 determine PGM/BPGM activity differences. The citrate-binding mode suggests a substrate-binding model, consistent with the structure of Escherichia coli dPGM/vanadate complex. A chloride ion was found in the center of the dimer, providing explanation for the contribution of chloride ion to dPGM activities. Based on the structural information, the possible reasons for the deficient human dPGM mutations found in some patients are also discussed.

Amino Acid Sequence↗
PubMed2005

Differential expression of GABAA receptor pi subunit in cultured rat alveolar epithelial cells.

Although type A gamma-aminobutyric acid (GABA) receptors (ligand-gated Cl(-) channels) have been extensively studied in the central nervous system, no information is available on this receptor in lung cells. We have examined the expression of GABA(A) receptor pi-subunit (GABRP) during the trans-differentiation between rat alveolar epithelial type II cells and type I cells. Rat alveolar type II cells, when cultured on plastic plates, gradually trans-differentiated into type-I-like cells and lost their GABRP mRNA expression. However, the GABRP mRNA was partially retained in the type II cells cultured on Matrigel. Keratinocyte growth factor (a mitogen of type II cells) increased GABRP expression. A detached collagen gel maintained the GABRP mRNA to a level close to that of the freshly isolated type II cells. An air-liquid interface culture system, mimicking in vivo conditions in the lung, significantly up-regulated the expression of GABRP mRNA and protein. mRNAs of the GABA(A) receptor alpha1-, alpha3-, beta2-, gamma2-, and gamma3-subunits were also detected in rat type II cells. These results suggest that GABRP expression is differentially regulated by culture substrata, growth factor, detached gel, and an air-apical surface.

Animals↗
PubMed2005

[Establishment of a model of retinal microglial cells activation in vitro].

OBJECTIVE: To develop a method of retinal microglial cell culture to study the function of the microglial cell in diabetic retinopathy. METHODS: Microglia were activated with LPS. Immunocytochemistry, con-focal microscopy, flow cytometry, MTT and ELISA were applied to observe the morphological characters, quantity, and functional changes of the microglia. RESULTS: The purity of the microglia was up to 96% as determined by immunostaining and flow cytometry. Some morphological changes of microglia were observed after treatment with LPS, but their quantity kept stable. Cytokine TNF-alpha released from microglia increased significantly. CONCLUSION: The isolated microglial cells are pure by using this culture system, which would provide a valuable tool for studying mechanisms of microglial alterations in diabetic retinopathy.

Animals↗
PubMed2005

Genotyping DNA pools on microarrays: tackling the QTL problem of large samples and large numbers of SNPs.

BACKGROUND: Quantitative trait locus (QTL) theory predicts that genetic influence on complex traits involves multiple genes of small effect size. To detect QTL associations of small effect size, large samples and systematic screens of thousands of DNA markers are required. An efficient solution is to genotype case and control DNA pools using SNP microarrays. We demonstrate that this is practical using DNA pools of 100 individuals. RESULTS: Using standard microarray protocols for the Affymetrix GeneChip Mapping 10 K Array Xba 131, we show that relative allele signal (RAS) values provide a quantitative index of allele frequencies in pooled DNA that correlate 0.986 with allele frequencies for 104 SNPs that were genotyped individually for 100 individuals. The sensitivity of the assay was demonstrated empirically in a spiking experiment in which 15% and 20% of one individual's DNA was added to a DNA pool. CONCLUSION: We conclude that this approach, which we call SNP-MaP (SNP microarrays and pooling), is rapid, cost effective and promises to be a valuable initial screening method in the hunt for QTLs.

Alleles↗
PubMed2005

RealSpot: software validating results from DNA microarray data analysis with spot images.

The spot images from DNA microarray highly affect the discovery of biological knowledge from gene expression data. However, results from quality analysis, normalization, differential expression, and cluster analysis are rarely validated with spot images in current data analysis methods or software packages. We designed RealSpot, a software package, to validate the results by directly associating spot quality and data with spot images in a spreadsheet table. RealSpot splits hybridization images into individual spots stored in a spreadsheet table. It subsequently associates microarray data with spot images and performs data validation through the standard table operation such as sorting, searching, and editing. RealSpot has several built-in functions to facilitate data validation, including spot quality analysis, data organization, one-way ANOVA, gene ontology association, verification, import, and export. We used RealSpot to evaluate 77 slides (30,000 features each) from real hybridization experiments and to validate results from each step of data analysis. It took approximately 10 min to validate results of spot quality after initial evaluation and correct approximately 0.3% of falsely assigned qualities of 10,000 spots. We validated 1,641 of 2,110 differentially expressed genes identified by SAM analysis in approximately 1/2 h by comparing each gene with its respective spot image. Furthermore, we found that 6 of 48 genes in one cluster from k-mean clustering method showed inconsistent trends of spot images. RealSpot is efficient for validating microarray results and thus helpful for improving the reliability of the whole microarray experiment for experimentalists.

Algorithms↗
PubMed2005

Clinical application of metallic stents in treatment of esophageal carcinoma.

AIM: To evaluate the effects of self-expanding metal stents (SEMS) in patients with malignant esophageal obstruction and to analyze their prognosis and complications. METHODS: Seventy-four metallic stents were placed under fluoroscopic guidance in 66 patients with esophageal obstruction secondary to carcinoma, of whom, 6 cases were complicated by fistula. RESULTS: After seventy-two stents were successfully used in 66 cases without any severe complications (technical successful rate was 97%), the dysphagia score improved from 3.3+/-0.6 to 0.8+/-0.5 (P<0.01), and life quality improved significantly in all these patients. All fistulae were sealed immediately after coated stents were inserted in the six patients. New stents were placed in two patients: the stent migrated more than 2 cm, in one patient and the stent slipped into stomach in the other. Minor bleeding was found only in 28 patients during the operation. Reobstruction was found in 12 patients, but was successfully cured under endoscopy. The survival rate was 78%, 57% and 11% for 6 mo, 1 year and 2 years respectively. CONCLUSION: Placement of SEMS is a simple, safe, quick and efficient surgical method for treating esophageal carcinoma obstruction. It may be used mainly as a palliative treatment of esophageal obstruction secondary to carcinoma.

Adult↗
PubMed2005

In vivo and in vitro oxidative regulation of rat aryl sulfotransferase IV (AST IV).

Sulfotransferase catalyzed sulfation is important in the regulation of different hormones and the metabolism of hydroxyl containing xenobiotics. In the present investigation, we examined the effects of hyperoxia on aryl sulfotransferase IV in rat lungs in vivo. The enzyme activity of aryl sulfotransferase IV increased 3- to 8-fold in >95% O2 treated rat lungs. However, hyperoxic exposure did not change the mRNA and protein levels of aryl sulfotransferase IV in lungs as revealed by Western blot and RT-PCR. This suggests that oxidative regulation occurs at the level of protein modification. The increase of nonprotein soluble thiol and reduced glutathione (GSH)/oxidized glutathione (GSSG) ratios in treated lung cytosols correlated well with the aryl sulfotransferase IV activity increase. In vitro, rat liver cytosol 2-naphthol sulfation activity was activated by GSH and inactivated by GSSG. Our results suggest that Cys residue chemical modification is responsible for the in vivo and in vitro oxidative regulation. The molecular modeling structure of aryl sulfotransferase IV supports this conclusion. Our gel filtration chromatography results demonstrated that neither GSH nor GSSG treatment changed the existing aryl sulfotransferase IV dimer status in cytosol, suggesting that oxidative regulation of aryl sulfotransferase IV is not caused by dimer-monomer status change.

Animals↗
PubMed2005

Assessing reliability, heritability and general cognitive ability in a battery of cognitive tasks for laboratory mice.

This report includes the first sibling study of mouse behavior, and presents evidence for a heritable general cognitive ability (g) factor influencing cognitive batteries. Data from a population of male and female outbred mice (n = 84), and a replication study of male sibling pairs (n = 167) are reported. Arenas employed were the T-maze, the Morris water maze, the puzzle box, the Hebb-Williams maze, object exploration, a water plus-maze, and a second food-puzzle arena. The results show a factor structure consistent with the presence of g in mice. Employing one score per arena, this factor accounts for 41% of the variance in the first study (or 36% after sex regression) and 23% in the second, where this factor also showed sibling correlations of 0.17-0.21, which translates into an upper-limit heritability estimate of around 40%. Reliabilities of many tasks are low and consequently set an even lower ceiling for inter-arena or sibling correlations. Nevertheless, the factor structure is seen to remain fairly robust across permutations of the battery composition and the current findings fit well with other recent studies.

Animals↗
PubMed2005

Telomere length predicts embryo fragmentation after in vitro fertilization in women--toward a telomere theory of reproductive aging in women.

OBJECTIVE: Telomeres are DNA repeats which cap and protect chromosome ends, facilitate homologue pairing and chiasmata formation during early meiosis, and shorten with cell division and exposure to reactive oxygen to mediate aging. Early germ cells contain telomerase, a reverse transcriptase which adds telomeres to 3-prime DNA ends, but telomerase activity declines in oocytes, fixing telomere length earlier during development. Experimentally induced telomere shortening in mice disrupts meiosis, impairs chiasmata formation, halts embryonic cell cycles, and promotes apoptosis in embryos, a phenotype which mimics reproductive senescence in women. Ethical constraints limit study of human embryos to nondestructive assays, such as morphologic evaluation under transmission optics, but cytoplasmic fragmentation is a reliable marker of apoptosis. STUDY DESIGN: Study design consisted of observational study of effect of telomere length in human eggs on cytoplasmic fragmentation, and on other morphologic features of preimplantation embryos. To test the hypothesis that telomere shortening triggers apoptosis in human embryos, we evaluated telomere length as a predictor of cytoplasmic fragmentation in embryos from women undergoing in vitro fertilization. RESULTS: Telomere length negatively predicted fragmentation in day 3 preimplantation embryos, after controlling for patient age and basal follicle stimulating hormone level. Telomere length did not predict other features of preimplantation embryo morphology. CONCLUSION: The finding that telomere length in human eggs predicts cytoplasmic fragmentation in embryos provides evidence that telomere shortening induces apoptosis in human preimplantation embryos, consistent with a telomere theory of reproductive senescence in women.

Adult↗
PubMed2005

Noninvasive imaging of spindle dynamics during mammalian oocyte activation.

OBJECTIVE: To develop a method to evaluate spindle dynamics in living oocytes and in karyoplasts during the initial stages of activation and after pharmacological disruption of cytoskeleton. DESIGN: Morphological study using a novel microscope. SETTING: Translational research laboratory at marine biological laboratory. ANIMAL(S): Six-week-old CD-1 or B6C3F1 mice superovulated with pregnant mare's serum gonadotropin and human chorionic gonadotropin (hCG). INTERVENTION(S): Spindles of living oocytes and karyoplasts were imaged at 5-10 minute intervals using the Pol-Scope during the initial stages of oocyte activation and after pharmacological disruption of cytoskeleton. MAIN OUTCOME MEASURE(S): Assessment of spindle dynamics using Pol-Scope imaging. RESULT(S): During oocyte activation, spindle mid-region birefringence increased, followed by spindle rotation and second polar body extrusion in both intact oocytes and karyoplasts. Activation of protein kinase C (PKC) with phorbol 12-myristate 13-acetate failed to induce spindle activation in 60% of living oocytes and caused spindle disruption in some oocytes. Inhibition of PKC by a myristoylated PKC pseudosubstrate inhibited metaphase II release in most oocytes evaluated (86.7%). Cytochalasin D inhibited only spindle rotation and separation. Nocodazole disrupted spindles in less than 5 minutes after administration. CONCLUSION(S): Pol-Scope imaging allows investigation at near real time of spindle dynamics during activation of living oocytes. Spindles also showed evidence of activation even in karyoplasts. The procedure may be useful for detecting functional spindle aberrations in living oocytes. Further studies are needed to determine whether spindle dynamics predict clinical outcome.

Animals↗
PubMed2005

[Relationships among expressions of hTERT, MDR1, MRP mRNA, and C-myc protein in non-small cell lung cancer].

BACKGROUND & OBJECTIVE: The latest researches showed that myc protein could up-regulate the expression of human telomerase reverse transcriptase (hTERT), multidrug resistance gene 1(MDR1), multidrug resistance-related protein (MRP) in some kinds of tumors, and hTERT is correlated with efficiency of anti-tumor chemotherapy. This study was to investigate relations among expressions of hTERT, MDR1, MRP mRNA, and C-myc protein in non-small cell lung cancer (NSCLC). METHODS: Expressions of hTERT, MDR1, MRP mRNA in 113 cases of NSCLC tissues were detected by in situ hybridization, expression of C-myc protein was detected by SP immunohistochemistry, their correlations with clinicopathologic features of NSCLC were statistically analyzed. RESULTS: Positive rates of hTERT, MDR1, MRP mRNA, and C-myc protein in NSCLC tissues were 80.5%, 51.3%, 80.5% and 68.1%, respectively. Expressions of MDR1, MRP mRNA, and C-myc protein were significantly related to that of hTERT mRNA (P<0.05). Expression of C-myc protein did not correlate with expression of MDR1 or MRP mRNA. All 4 factors have no correlation with clinicopathologic features of NSCLC (P>0.05). CONCLUSION: Expression of hTERT mRNA may be related to those of MDR1, MRP mRNA, and C-myc in NSCLC. Overexpression of C-myc protein may be one of the molecular regulatory mechanisms of hTERT mRNA.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

[Observation on the biological behavior of human umbilical cord blood adherent cells].

To study the possibility of separation and culture of human umbilical cord blood adherent cell (HUCBAC), the umbilical cord blood CD34(+) cells were cultured in Dexter system in order to evaluate and observe the biological behavior of adherent cells in vitro. The results showed that all cells were cultured with Dexter system. By day 9-14 (at a median of 11.2 days), adherent cell colonies formed and reached their maximum at 15-22 days (mean 19.6 days), by day 28, all adherent cells spread over the bottom of Petri dish. By means of light microscopy, these cells were found to differentiate into three kinds of cells in culture of 28 days: fibroblast-liked cell, macrophage liked cell and small-round cells. The ratio of these three kinds of cells was 56.8%, 38%, 5.5% respectively. Cytochemistry assay revealed that the positive rate reached 100% in NSE stain and PAS stain; the adherent cell by ALP stain were shown 35% positive, but in POX stain the result was negative. Immunohistochemistry stain revealed that the positive rate of cord adherent cells for CD106, CD29, CD44, CD45, CD50, Fn, Ln, collagen IV etc reached 96%, 93%, 98%, 68%, 72%, 92%, 74%, 83% respectively. It is concluded there are hematopoietic adherent precursors in cord blood CD34(+) cells and the HUCBAC shows some biological behavior of hematopoietic stromal cells.

Antigens, CD34↗
PubMed2005

[Influence of anti-CXCR4 monoclonal antibody 12G5 on killing effect of cytosine arabinoside to HL-60 cell].

This study was aimed to explore the influence of anti-CXCR4 monoclonal antibody 12G5 on killing effect of cytosine arabinoside (Ara C) to HL-60 cell, and to assess its therapeutic value in marrow residual disease. HL-60 cells were cultured and co-cultured with leukemic stromal cells, and SDF-1 activity was inhibited with 10 microg/ml 12G5, then, killing effects of Ara C on HL-60 cells were investigated by MTT and morphology assay. Curves by MTT assay revealed that in the test group of 20 microg/ml Ara C, A(540) values decreased slowly but straightly, however, in control group A(540) values decreased markedly for the first two days, and increased from day 3 or 4. In the test group of 40 microg/ml Ara C, although increasing at constricted range of 7 - 9 days, A(540) values decreased in whole observing period of 12 days, while in control group A(540) values decreased markedly at day 0-3, and increased from day 4. Furthermore, two curves go across each other at day 5, and continue the increasing tendency. Morphology results showed that in both treated groups, the number of HL-60 cell decreased markedly and increased gradually in control group, but just contrary to test group. It is concluded that 12G5 may weaken the killing effect of Ara C on HL60 cell in earlier period, but reinforce the total killing effect and delay the occurrence of drug resistance simultaneously. Thus 12G5 has the therapeutic potential on marrow residual disease.

Antibodies, Monoclonal↗
PubMed2005

[Expression of stromal cell derived factor-1(SDF-1) and its receptor CXCR4 in hematologic malignancies].

The aim was to analyze the expression level of stromal cell derived factor-1 (SDF-1) and its functional chemokine receptor CXCR4 in the patients with hematologic malignant tumor and their clinic significance. 28 patients with hematologic malignant tumor and 12 normal controls were chosen to be experimental objects. CXCR4 expressed on the cell membrane in bone marrow was enumerated by flow cytometry and serum level of SDF-1 was determined by ELISA assay. The result showed that the expression of SDF-1 and CXCR4 in hematologic malignant tumor were higher than that in normal controls, and the expression levels of two molecules were correlated. What is more, the different hematologic malignant tumor had different CXCR4 expression. In conclusion, the high expression of SDF-1 and CXCR4 in serum and bone marrow cells can be used as detective factors to hematologic malignant tumor. A correlation exists between the high expression of CXCR4 and the infiltration of hematologic malignant cells.

Adolescent↗
PubMed2005

[One-step purification of monoclonal antibody against gp130 by cation exchange liquid chromatography].

AIM: To develop a one-step purification method of anti-gp130 monoclonal antibody (mAb) B-S12 from mouse ascites. METHODS: After filtrated by centrifugation, the ascites sample was loaded on a cation exchange column and purified by using ion-strength gradient elution buffer. The effects of pH of the loading buffer and ion strength gradients of the elution buffer on the purity of antibody obtained were investigated. The antibody's biological activity was tested by MTT colorimetry. RESULTS: It was shown that the mAb B-S12 with a purity of over 90% could be achieved by using 20 mmol/L HEPES buffer (pH 4.0) as loading buffer and 0-1.0 mol/L NaCl as elution buffer. The total recovery rate of the mAb was 52%. The purified antibody could stimulate the proliferation of XG-2 cell line. CONCLUSION: The established one-step purification method was simple and suitable for purification of mAb B-S12.

Animals↗
PubMed2005

[Mechanism of keratinocyte growth factor-2 accelerating corneal epithelial wound healing on rabbit alkali burned cornea].

OBJECTIVE: To evaluate the curative effect of KGF-2 on the alkali-injured rabbit eye and to investigate the mechanism of KGF-2 accelerating corneal epithelial wound healing. METHODS: Alkali burn was produced in 24 corneas from 24 New Zealand rabbits. Four groups were randomly divided. Three groups (A, B, and C groups) were treated with KGF-2 solution (1, 50, 100 microg/ml, respectively), and one group (D group) was treated with phosphate-buffered saline (PBS) solution. The injured eyes were photographed after the fluorescence staining with a slit lamp and the pictures were analyzed with computer-aided picture analysis system to calculate the rate of corneal epithelial healing. Morphologic and immunohistological examinations (using P63, AE5 and EGFR antibodies) of the cornea were performed. RESULTS: KGF-2 at dosages ranging from 1 microg/ml to 100 microg/ml could enhance the cornea wound healing process. After 24 hours, epithelial healing rate of the 100 microg/ml KGF-2 group and the PBS treated group was 74% and 40%, respectively (P < 0.05). The corneal epithelial healing rate of each group was variable after four days and achieved complete healing after ten days. The P63 positive cells in KGF-2 groups appeared not only in the limbal area but also in the central area. For example, on the seventh day, in the limbal area, the P63 positive cells in the 100 microg/ml KGF-2 group, the PBS treated group and the normal group were 53.8 +/- 2.6, 29.5 +/- 2.2 and 17.0 +/- 2.1, respectively (P = 0.000). At the same time, the P63 positive cells in the non-limbal area in the 100 microg/ml KGF-2 group, the PBS treated group and the normal group were 69.5 +/- 2.8, 19.5 +/- 2.8 and 0, respectively (P = 0.000). CONCLUSIONS: These results suggested KGF-2 can stimulate the limbal epithelial stem cells to migrate to the central cornea. KGF-2 can accelerate the healing of alkali burned cornea.

Alkalies↗
PubMed2005

[Study on the expression of IL-10 mRNA and the protein in gingival tissues of patients with chronic periodontitis].

PURPOSE: To investigate the cell type which express IL-10 mRNA and the protein in gingival tissues of patients with chronic periodontitis. METHODS: 12 patients with chronic periodontitis who were undergoing flap operation were randomly chosen as periodontitis group;10 patients undergoing gingivectomy were chosen as gingivitis group;6 patients undergoing extraction of impacted teeth were chosen as control group. Assays of in situ hybridization and immunohistochemistry were used to observe the expression of IL-10 mRNA and the protein in gingival tissues of each group respectively . Wilcoxon test was used to compare the expression of IL-10 of each group at two levels; differences between the two groups were analyzed by one-way ANOVA test. RESULTS: IL-10 mRNA and the protein were all expressed in gingival tissues of periodontium,they were found in lymphocytes, fibroblasts and macrophages. There were no significant differences between two levels of IL-10 expression of periodontitis group and control group (P>0.05) gingivitis group,P<0.05). The IL-10 expression of periodontitis group was significantly higher than gingivitis group and control group (P<0.01); The IL-10 mRNA expression of periodontitis group was significantly higher than control group (P<0.01),but there was no significant difference between the IL-10 mRNA expression of periodontitis group and gingivitis group (P>0.05). CONCLUSION: There is a local secretion mechanism of IL-10 in the periodontal tissues.

Case-Control Studies↗