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Yan Liu

Publications and source records attributed to Yan Liu.

At least 145 records · Page 8Linked to original sources
PubMed2006

[Expression of E-cadherin and beta-catenin in Bowen's disease and squamous cell carcinoma].

OBJECTIVE: To investigate the involvement of E-cadherin-catenin adhesion system in Bowen's disease (BD) and cutaneous squamous cell carcinoma (SCC). METHODS: Fifteen normal skin, 28 BD and 18 SCC specimens were stained with monoclonal antibodies against E-cadherin and beta-catenin. Evaluation of the staining results was performed with semi-quantification of the pattern and intensity of staining, percentage of positive cells, and cytoplasmic staining. RESULT: Normal skins strongly expressed membranous E-cadherin and beta-catenin, but their expression was remarkably reduced in BD and SCC. Abnormal staining of beta-catenin was observed in the cytoplasm or cell nuclei of BD and SCC. CONCLUSION: Abnormal expression of the E-cadherin/catenin complex is common in SCC and BD.

Adult↗
PubMed2006

[Optical-fiber Fourier transform spectrometer].

A novel Fourier transform spectrum analyzer based on a single mode fiber Mach-Zehnder interferometer is reported. An optical fiber Fourier transform spectrometer, with bulk optics components replaced by fiber optical components and with the moving mirror replaced by a piezoelectric element fiber stretcher was constructed. The output spectrum of a LD below threshold was measured. Experiment result agrees with that by using grating spectrum analyzer, showing the feasibility of the optic fiber Fourier transform spectrometer for practical spectrum measurement. Spectrum resolution -7 cm(-1) was obtained in our experiment. The resolution can be further improved by increasing the maximum optical path difference.

English Abstract↗
PubMed2005

Self-assembling a molecular pegboard.

This paper describes the design, construction, and application of a self-assembled, chemically addressable DNA nanogrid composed of DNA tiles of nanometer dimensions. This self-assembled structure permits precise placement of molecules at predetermined locations on a "molecular pegboard". We used the indexed DNA nanogrids to identify single molecules of DNA that hybridize at particular locations.

DNA↗
PubMed2005

Health insurance coverage in survivors of childhood cancer: the Childhood Cancer Survivor Study.

PURPOSE: To examine the prevalence and predictors of health insurance coverage and the difficulties obtaining coverage in a large cohort of childhood cancer survivors. PATIENTS AND METHODS: This study included 12,358 5-year survivors of childhood cancer and 3,553 sibling controls participating in the Childhood Cancer Survivor Study. Data were collected by surveys distributed in 1994 (baseline) and 2000 (follow-up). RESULTS: At baseline, 83.9% of adult survivors, compared with 88.3% of siblings, had health insurance coverage (P < .01); 6 years later, small but significant survivor-sibling differences remained (88% v 91%; P < .01). Twenty-nine percent of survivors reported having had difficulties obtaining coverage, compared with only 3% of siblings (P < .01). In multivariate analysis of survivors 18 years of age or older, factors associated with being uninsured included younger age at diagnosis (diagnosis age of 0 to 4 years; odds ratio [OR] = 1.7; 95% CI, 1.3 to 2.2), male sex (OR = 1.3; 95% CI, 1.2 to 1.5), age at baseline survey (age 22 to 24 years; OR = 1.6; 95% CI, 1.2 to 2.1), lower level of attained education (less than high school, OR = 2.6, 95% CI, 2.1 to 3.3; high school graduate, OR = 2.1, 95% CI, 1.8 to 2.5), income less than 20,000 dollars (OR = 5.6, 95% CI, 4.5 to 7.1), marital status (widowed/divorced/separated; OR = 1.3; 95% CI, 1.1 to 1.6), smoking status (current smoker, OR = 2.0, 95% CI, 1.7 to 2.3; former smoker, OR = 1.4, 95% CI, 1.2 to 1.8), and treatment that included cranial radiation (OR = 1.3, 95% CI, 1.0 to 1.6). CONCLUSION: Compared with siblings, adult survivors of childhood cancer had significantly lower rates of health insurance coverage and more difficulties obtaining coverage. Since lack of coverage likely has serious health and financial implications for this at-risk population, any disparity in availability and quality of coverage is of great concern.

Adolescent↗
PubMed2005

[Short circuit current technology and its application in the study of traditional Chinese medicine].

Short circuit current (I(sc)) technique has been applied in the studies of transepithelial ion transport in various epithelia. Recently it has also been used in the modernization researches on traditional Chinese medicines. This review gives an overview of the basic principle of the I(sc) technique, the targets of measurement, ion transport, ion channel, the general ways of I(sc) research design, the application of I(sc) technology in the researches on traditional Chinese medicines.

Animals↗
PubMed2005

Self-assembly of symmetric finite-size DNA nanoarrays.

We report a novel and cost-effective strategy to self-assemble finite-size DNA nanoarrays. This strategy takes advantage of the geometric symmetry of the DNA nanostructures. In general, to construct a 2D array with a total of N tiles containing Cm symmetry, where m = 2, 3, 4, or 6, the number of unique tiles the fixed-size array requires is N/m, if N/m is an integral number, or Int(N/m) + 1, if N/m is an nonintegral number. We herein demonstrate two examples of fixed-size arrays with C2 and C4-fold symmetry.dagger

DNA↗
PubMed2005

Transactivation of Abl by the Crk II adapter protein requires a PNAY sequence in the Crk C-terminal SH3 domain.

To gain a better understanding of how Crk II regulates the function of the Abl tyrosine kinase, we explored the function of the C-terminal linker and SH3 domain, a region of Crk II that is still poorly understood. Molecular modeling, tryptophan fluorescence, and covariation sequence alignment indicate that the Crk-SH3-C has a unique binding groove and RT loop not observed in typical SH3 domains. Based on these models, we made a series of mutations in the linker and in residues predicted to destabilize the putative binding pocket and RT loop. In Abl transactivation assays, Y222F and P225A mutations in the linker resulted in strong transactivation of Abl by Crk II. However, mutations predicted to be at the surface of the Crk SH3-C were not activators of Abl. Interestingly, combinations of activating mutations of Crk II with mutations in the highly conserved PNAY sequence in the SH3-C inactivated the activating mutations, suggesting that the SH3-C is necessary for activation. Our data provide insight into the role of highly conserved residues in the Crk-SH3-C, suggesting a mechanism for how the linker and the Crk-SH3-C function in the transactivation of the Abl tyrosine kinase.

Amino Acid Sequence↗
PubMed2005

Nucleus accumbens dopamine differentially mediates the formation and maintenance of monogamous pair bonds.

The involvement of dopamine within the nucleus accumbens in the formation and maintenance of pair bonds was assessed in a series of experiments using the monogamous prairie vole. We show that dopamine transmission that promotes pair bond formation occurs within the rostral shell of the nucleus accumbens, but not in its core or caudal shell. Within this specific brain region, D1- and D2-like receptor activation produced opposite effects: D1-like activation prevented pair bond formation, whereas D2-like activation facilitated it. After extended cohabitation with a female, male voles showed behavior indicative of pair bond maintenance-namely, selective aggression towards unfamiliar females. These voles also showed a significant upregulation in nucleus accumbens D1-like receptors, and blockade of these receptors abolished selective aggression. Thus, neuroplastic reorganization of the nucleus accumbens dopamine system is responsible for the enduring nature of monogamous pair bonding. Finally, we show that this system may also contribute to species-specific social organization.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed2005

[A multi-central, randomized, controlled clinical trial of glucosamine hydrochloride/sulfate in the treatment of knee osteoarthritis].

OBJECTIVE: To evaluate the efficacy and safety of glucosamine hydrochloride (GH) in the treatment of patients with knee osteoarthritis (OA) comparing with glucosamine sulfate (GS). METHODS: A multi-central, randomized, parallel-controlled clinical trial of GH vs GS was performed. 142 patients suffering from knee OA were randomized into 2 groups, treated with GH and GS for 480 mg and 500 mg one time respectively. Patients received medicine 3 times daily with total 1440 mg per day for GH group and 1500 mg for GS group, orally for 4 weeks and were assessed for drug efficacy and safety for 2 more weeks. Knee pain at rest, at movement and at pressure, knee swelling, morning stiffness and walking ability were recorded at 1, 2, 3, 4 and 6 week according to Lequesne's criteria. Other features such as therapeutic efficacy, adverse events and laboratory parameters were also recorded. RESULTS: A considerable improvement in OA symptoms and a reduce of total Lequesne's score were observed in both groups after the 4-week treatment. The Lequesne's score decreased to 3.4 +/- 1.9 (P < 0.05) and 3.4 +/- 1.8 (P < 0.05) after 4-week treatment comparing to 0-week in the GH (9.4 +/- 1.8) group and GS (9.5 +/- 1.4) group respectively. There was no significant difference between 2 groups in decreasing the Lequesne's score (P > 0.05). The symptomatic improvement rates in patients were 91.4% and 90.0% at 4-week treatment in the GH and GS group respectively (P > 0.05). There was a remnant therapeutic effect in both groups at 2 weeks after discontinuation of the treatment. And 4.2% (3/71) of patients on GH reported adverse events, vs 7.0% (5/71) adverse events with GS group (P > 0.05), mainly mild stomach discomfort and constipation. CONCLUSION: There were no significant differences in efficacy and safety between GH and GS groups in the treatment of knee OA. Glucosamine hydrochloride is as effective and safe as glucosamine sulfate.

Administration, Oral↗
PubMed2005

Apoptosis of allospecifically activated human helper T cells is blocked by calcineurin inhibition.

BACKGROUND: Classical transplantation immunosuppression relies heavily upon the interruption of interleukin-2 (IL-2) signaling by calcineurin inhibition. However, recent evidence in murine models suggests that IL-2 is necessary for activation-induced cell death (AICD) of allograft-specific lymphocytes. METHODS: We examined the apoptotic effects of the calcineurin inhibitor cyclosporine A and mTOR inhibitor rapamycin on the apoptotic alterations that occur in allospecifically activated human lymphocytes in a one-way mixed lymphocyte culture (MLC). RESULTS: Cyclosporine increased caspase-3 activation in MLC, which corresponded with a decrease in lymphocyte apoptosis in MLC. Cyclosporine also reduced apoptosis in the CD4+ helper T cell subset, while CD8+ cells had similar or increased apoptosis when compared to controls. In contrast, rapamycin-treated cultures had normal levels of CD4+ T cell apoptosis when compared to control MLC, with decreases seen in CD8+ T lymphocytes. CONCLUSIONS: In humans, blockade of IL-2 receptor signal with rapamycin allows apoptosis of allospecifically activated CD4+ lymphocytes to occur, while blockade of IL-2 production with cyclosporine results in decreased apoptosis in this T cell subset. As helper T cells are integral to the immune response, these results may explain the tolerogenic effects of rapamycin.

Apoptosis↗
PubMed2005

Central and peripheral axon branches from one neuron are guided differentially by Semaphorin3D and transient axonal glycoprotein-1.

For multiple axons from one neuron to extend in different directions to unique targets, the growth cones of each axon must have distinct responses to guidance cues. However, the mechanisms by which separate axon branches are guided along different pathways are mainly unknown. Zebrafish Rohon-Beard (R-B) sensory neurons extend central axon branches in the spinal cord and peripheral axons to the epidermis. To investigate the differential guidance mechanisms of the central versus peripheral R-B axon branches, we used live-growth cone imaging in vivo combined with manipulation of individual guidance molecules. We show that a semaphorin expressed at the dorsal spinal cord midline, Semaphorin3D (Sema3D), may act to repel the peripheral axons out of the spinal cord. Sema3D knock-down reduces the number of peripheral axons. Remarkably, Sema3D ectopic expression repels and induces branching of peripheral axons in vivo but has no effect on central axons from the same neurons. Conversely, central axons require a growth-promoting molecule, transient axonal glycoprotein-1 (TAG-1), to advance, whereas peripheral axons do not. After TAG-1 knock-down, central growth cones display extensive protrusive activity but make little forward advance. TAG-1 knock-down has no effect on the motility or advance of peripheral growth cones. These experiments show how Sema3D and TAG-1 regulate the motility and behavior of growth cones extending in their natural in vivo environment and demonstrate that two different axon branches from one neuron respond differently to guidance cues in vivo.

Amino Acids↗
PubMed2005

Effects of Helicobacter pylori eradication on atrophic gastritis and intestinal metaplasia: a 3-year follow-up study.

AIM: To investigate the effect of H pylori eradication on atrophic gastritis and intestinal metaplasia (IM). METHODS: Two hundred and fifty-nine patients with atrophic gastritis in the antrum were included in the study, 154 patients were selected for H pylori eradication therapy and the remaining 105 patients served as untreated group. Gastroscopy and biopsies were performed both at the beginning and at the end of a 3-year follow-up study. Gastritis was graded according to the updated Sydney system. RESULTS: One hundred and seventy-nine patients completed the follow-up, 92 of them received H pylori eradication therapy and the remaining 87 H pylori-infected patients were in the untreated group. Chronic gastritis, active gastritis and the grade of atrophy significantly decreased in H pylori eradication group (P<0.01). However, the grade of IM increased in H pylori -infected group (P<0.05). CONCLUSION: H pylori eradication may improve gastric mucosal inflammation, atrophy and prevent the progression of IM.

Adult↗
PubMed2005

Oligosaccharide analysis by capillary-scale high-pH anion-exchange chromatography with on-line ion-trap mass spectrometry.

A capillary-scale high-pH anion-exchange chromatography (HPAEC) system for the analysis of carbohydrates was developed, in combination with two parallel on-line detection methods of sub-picomolar sensitivity: (1) pulsed amperometric detection (PAD); (2) capillary-scale desalting followed by electrospray ion-trap (IT) mass spectrometry (MS). The capillary chromatographic system combined the superb selectivity of HPAEC that allows routine separation of isomeric oligosaccharides with the information on monosaccharide sequence and linkage positions obtained by MS/MS fragmentation using the IT-MS. The applicability of the system in biomedical research was demonstrated by its use for the analysis of a urine sample of a GM1-gangliosidosis patient. Isomeric glycans in the sample could be resolved by HPAEC and assigned on the basis of the monosaccharide linkage information revealed by on-line IT-MS/MS.

Chromatography, Ion Exchange↗
PubMed2005

Effect of pH change on the performance and microbial community of enhanced biological phosphate removal process.

An acetate-rich wastewater, containing 170 mg/L of total organic carbon (TOC), 13 mg/L of N, and 15 mg/L of P, was treated using the enhanced biological phosphate removal (EBPR) process operated in a sequencing batch reactor. A slight change of pH of the mixed liquor from 7.0 to 6.5 led to a complete loss of phosphate-removing capability and a drastic change of microbial populations. The process steadily removed 94% of TOC and 99.9% of P from the wastewater at pH 7.0, but only 93% TOC and 17% of P 14 days after the pH was lowered to pH 6.5. The sludge contained 8.8% P at pH 7.0, but only 1.9% at pH 6.5. Based on 16S rDNA analysis, 64.8% of the clones obtained from the sludge at pH 7.0 were absent in the pH 6.5 sludge. The missing microbes, some of which were likely responsible for the phosphate removal at pH 7.0, included beta-Proteobacteria, Actinobacteria, Bacteriodetes/Chlorobi group, plus photosynthetic bacteria and Defluvicoccus of the alpha-Proteobacteria. Among them, the last two groups, which represented 9.3% and 10.1% of the EBPR sludge at pH 7.0, have rarely been reported in an EBPR system.

Bacteria↗
PubMed2005

Design and fabrication of narrow-frequency sharp angular filters.

The theoretical deduction for the frequency variations of the defect mode and its dependence on the incident angle in one-dimensional defective photonic crystals is discussed. Filters with the dual function of narrow frequency passbands and sharp angular pass breadths in visible and near-infrared wave bands, in which both the defect mode and the periodic structure are layers of integral times of quarter-wavelengths, were designed. This kind of filter was fabricated with commonly used coating machines.

Journal Article↗
PubMed2005

New amperometric and potentiometric immunosensors based on gold nanoparticles/tris(2,2'-bipyridyl)cobalt(III) multilayer films for hepatitis B surface antigen determinations.

Two generic, fast, sensitive and novel electrochemical immunosensors have been developed. Initially, a layer of plasma-polymerized Nafion film (PPF) was deposited on the platinum electrode surface, then positively charged tris(2,2'-bipyridyl)cobalt(III) (Co(bpy)(3)(3+)) and negatively charged gold nanoparticles were assembled on the PPF-modified Pt electrode by layer-by-layer technique. Finally, hepatitis B surface antibody (HBsAb) was electrostatically adsorbed on the gold nanoparticles surface. Electrochemical behavior of the {Au/Co(bpy)(3)(3+)}(n) multilayer film-modified electrodes was studied. Cyclic voltammetry, electrochemical impedance spectroscopy (EIS) were adopted to monitor the regular growth of the multilayer films. The performance and factors influencing the performance of the resulting immunosensors were studied in detail. The multilayer film-modified immunosensor was used for hepatitis B surface antigen (HBsAg) determination via the amperometric and potentiometric immunosensor systems, and both systems provided the same linear ranges from 0.05 to 4.5 microg/mL with different detection limits for the amperometric system 0.005 microg/mL and for the potentiometric system 0.015 microg/mL. The immunosensors were used to analyse HBsAg in human serum samples. Analytical results of clinical samples show that the developed immunoassay is comparable with the enzyme-linked immunosorbent assays (ELISAs) method, implying a promising alternative approach for detecting HBsAg in the clinical diagnosis. In addition, the multilayer films also showed better stability for 1 month at least.

2,2'-Dipyridyl↗
PubMed2005

Screening of hepatocyte proteins binding to F protein of hepatitis C virus by yeast two-hybrid system.

AIM: To investigate the biological function of F protein by yeast two-hybrid system. METHODS: We constructed F protein bait plasmid by cloning the gene of F protein into pGBKT7, then recombinant plasmid DNA was transformed into yeast AH109 (a type). The transformed yeast AH109 was mated with yeast Y187 (alpha type) containing liver cDNA library plasmid in 2XYPDA medium. Diploid yeast was plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing X-alpha-gal for selection and screening. After extracting and sequencing plasmids from positive (blue) colonies, we underwent sequence analysis by bioinformatics. RESULTS: Thirty-six colonies were selected and sequenced. Among them, 11 colonies were zymogen granule protein, 5 colonies were zinc finger protein, 4 colonies were zinc-alpha-2-glycoprotein, 1 colony was sialyltransferase, 1 colony was complement control protein factor I, 1 colony was vitronectin, and 2 colonies were new genes with unknown function. CONCLUSION: The yeast two-hybrid system is an effective method for identifying hepatocyte proteins interacting with F protein of hepatitis C virus. F protein may bind to different proteins.

Cell Line, Tumor↗