Biomedical subjects

Xiao-Ping Liu

Publications and source records attributed to Xiao-Ping Liu.

9 recordsLinked to original sources

PubMed2006

Acoustic backward-wave negative refractions in the second band of a sonic crystal.

Acoustic negative refractions with backward-wave (BW) effects were both theoretically and experimentally established in the second band of a two-dimensional (2D) triangular sonic crystal (SC). Intense Bragg scatterings result in the extreme deformation of the second band equifrequency surface (EFS) into two classes: one around the K point and the other around the point of the reduced Brillouin zone. The two classes can lead to BW negative refractions (BWNRs) but with reverse negative refraction dependences on frequencies and incident angles. Not only BWNR but BW positive refraction can be present at EFSs around the K point, so it is possible to enhance the resolution of acoustic waves with a subdiffraction limit regardless of refractions, which is no analogy in both left-handed material and SCs' first band. These abundant characters make refractions in the second band distinguished.

Journal Article↗

PubMed2006

[Construction and identification of recombinant vectors carrying herpes simplex virus thymidine kinase genes expressed in vascular endothelial cells].

BACKGROUND & OBJECTIVE: Blocking tumor angiogenesis is a promising tumoricidal approach. Herpes simplex virus-thymidine kinase (HSV-tk) suicide gene could effectively damage neoplastic vascular endothelial cells. However, the killing effect of currently used HSV-tk system is non-specific due to employing cytomegalovirus (CMV) as its promoter. Kinase domain insert containing receptor (KDR), a kind of vascular endothelial growth factor receptor, is highly expressed on tumor vascular endothelial cells, but lowly expressed on normal tissues. This study was to construct a recombinant adenovirus containing KDR promoter-mediated HSV-tk suicide gene, and analyze its specific expression on vascular endothelial cells. METHODS: KDR-tk fragment was subcloned into corresponding restriction sites of vector with directional cloning method using pAdeasy system to construct recombinant adenoviral plasmid containing KDR promoter-controlled HSV-tk gene (AdKDR-tk). After packaged and amplified in 293 cells, the virus was used to infect KDR-expressed human umbilical venous endothelial cells (HUVECs) and KDR-unexpressed liver cancer cell line HepG2. After administration of ganciclovir (GCV), proliferation of gene-transfected HUVECs and HepG2 cells was evaluated by MTT assay. RESULTS: According to the results of restriction digestion, reverse transcription-polymerase chain reaction (RT-PCR) and PCR, the length, position and orientation of inserted genes were correct. The titer of the recombinant adenovirus was 1 x 10 (10) pfu/ml. Under infection index of 100, with the concentration of GCV increased from 0 to 50 microg/ml, the survival rates of AdKDR-tk-transfected HUVECs and HepG2 cells decreased from 100% to (28.94+/-5.67)% and (75.45+/-2.91)%, respectively (P<0.01). CONCLUSION: Adenovirus-mediated transfection of KDR promoter-HSV-tk gene could direct endothelial specific gene expression.

Adenoviridae↗

PubMed2005

[Genetic linkage analysis in localizing a gene of autosomal dominant familial dilated cardiomyopathy with conduction defect].

OBJECTIVE: To localize the gene of autosomal dominant familial dilated cardiomyopathy with conduction defect. METHODS: A Chinese family which was diagnosed as dilated cardiomyopathy with conduction defect was studied. Venous blood (3 - 5 mL) from some family members was collected, and genomic DNA was extracted from the blood. Then whole genome wide scan was performed after excluding the known markers on the candidate loci (CMD1A, CMD1 E, CMD1F, and CMD1H) by two-point linkage analysis. RESULTS: No significant evidence for linkage was found in the two point linkage analyses to the known markers in the analyzed family. And the whole genome wide scan showed the maximum LOD score reached 2.68 at marker D3S1614 ( at recombination fraction theta = 0). CONCLUSION: The related gene in this kindred is located on 3q26 other than on CMD1A, CMD1H, CMD1E, and CMD1F.

Adult↗

PubMed2005

[Hotspot of the mutations of keratin 9 gene in a diffuse palmoplantar keratoderma family].

OBJECTIVE: To identify the gene causing diffuse palmoplantar keratoderma in a Chinese pedigree. METHODS: Four normal individuals and 3 patients in a diffuse palmoplantar keratoderma family and 10 unrelated control samples were recruited. The hotspot of the mutations of keratin 9 gene was analyzed by polymerase chain reaction and direct sequencing. RESULTS: We found a G485A transition in ke ratin 9 gene, resulting in the substitution of glutamine for arginine at codon 162 in this diffuse palmoplantar keratoderma family. The mutation was not found in the 10 unrelated control samples and 4 normal individuals. CONCLUSION: The mutation G485A found in keratin 9 gene is the disease-causing mutation in the diffuse palmoplantar keratoderma family.

Base Sequence↗

PubMed2004

[A novel oligonucleotide arrays-based multiplex amplifiable probe hybridization technology].

Multiplex amplifiable probe hybridization (MAPH) has recently been developed to detect gene copy number changes in total genome in several genetic disease. Here we reported a novel oligonucleotide arrays-based multiplex amplifiable probe hybridization technology for DNA fragment copy number measurement. A set of amplifiable probes were prepared by locus-specific forward and reverse primers synthesized with the T7 and T3 promoter sites at their respective 5'-ends to the interest DNA fragments and purified by Qiagen PCR products purification kit. The set of probes were then hybridized with genome DNA immobilized on the nylon membrane. The selective probes after MAPH were collected with streptavidin coated magnetic beads and amplified by a biotin labeled universal primers. The biotinylated PCR products were then intended for hybridization to the corresponding oligonucleotide arrays consisted of 10 exons of DMD gene probes and positive,negative control probes immobilized on glass slides. After hybridization, the slides were washed by hybridization buffer and stained by streptavidin-Cy3. The hybridization fluorescence images were scanned by the ScanArray software and further quantitatively analyzed by the ImageJ software. Here we used oligonucleotide array technology to replace the agarose gel analysis for detecting the biotinylated PCR products so that extendable ability of parallel assay in our method had greatly been improved. One control female, one control male and one DMD patient were tested in this study. The results demonstrate the feasibility of high-throughput detection and relative quantification of DNA fragment copy numbers changes in total genome DNA combination of MAPH and high-density oligonucleotide arrays in single reaction.

Gene Dosage↗

PubMed2003

Expression of growth hormone receptor and its mRNA in hepatic cirrhosis.

AIM: To investigate the expression of growth hormone receptor (GHR) and mRNA of GHR in cirrhotic livers of rats with the intension to find the basis for application of recombinant human growth hormone (rhGH) to patients with liver cirrhosis. METHODS: Hepatic cirrhosis was induced in Sprague-Dawley rats by administration of thioacetamide intraperitoneally for 9-12 weeks. Collagenase IV was perfused in situ for isolation of hepatocytes. The expression of GHR and its mRNA in cirrhotic livers was studied with radio-ligand binding assay, RT-PCR and digital image analysis. RESULTS: One class of specific growth hormone-binding site, GHR, was detected in hepatocytes and hepatic tissue of cirrhotic livers. The binding capacity of GHR (R(T), fmol/mg protein) in rat cirrhotic liver tissue (30.8+/-1.9) was significantly lower than that in normal control (74.9+/-3.9) at the time point of the ninth week after initiation of induction of cirrhosis (n=10, P<0.05), and it decreased gradually along with the accumulation of collagen in the process of formation and development of liver cirrhosis (P<0.05). The number of binding sites (X10(4)/cell) of GHR on rat cirrhotic hepatocytes (0.86+/-0.16) was significantly lower than that (1.28+/-0.24) in control (n=10, P<0.05). The binding affinity of GHR among liver tissue, hepatocytes of various groups had no significant difference (P>0.05). The expression of GHR mRNA (riOD, pixel) in rat cirrhotic hepatic tissues (23.3+/-3.1) was also significantly lower than that (29.3+/-3.4) in normal control (n=10, P<0.05). CONCLUSION: The growth hormone receptor was expressed in a reduced level in liver tissue of cirrhotic rats, and lesser expression of growth hormone receptors was found in a later stage of cirrhosis. The reduced expression of growth hormone receptor was partly due to its decreased expression on cirrhotic hepatocytes and the reduced expression of its mRNA in cirrhotic liver tissue.

Acetamides↗

PubMed2003

[Silica nanoparticles modified as carriers for gene transfection].

The silica nanoparticles are modified by sodium iodine or sodium chloride with different concentration. Their ability to bind and protect plasmid DNA was demonstrated by agarose gel electrophoresis. The EGFP-N1 plasmid was transfected into HT1080 by combing silica nanoparticle. Eletromicroscope examine revealed that nanoparticle-DNA could enter into cells, these silica nanoparticles protect DNA against nuclease digestion and the GFP has an effective expression. In conclusion, these nanoparticles might be used as DNA carriers for gene transfection.

Animals↗

PubMed2002

Protective effect of polypeptide from Chlamys farreri on hairless mice damaged by ultraviolet A.

AIM: To study the protective effect of the polypeptide isolated from Chlamys farreri (PCF) on hairless mice skin damaged by ultraviolet A. METHODS: Enzymes and malondialdehyde (MDA) were determined by biochemical methods; the expressions of Bcl-2 protein and NOS protein were examined by immunohistochemical technique. The ultra-structure of the skin was observed through electronic microscope. RESULTS: PCF could enhance the activities of glutathione peroxidase (GSH-px), superoxide dismutase (SOD), and total anti-oxidative capacity (T-AOC). Also PCF could reduce the amount of MDA, increase the expression of Bcl-2 protein, and inhibit the expression of NOS protein. The ultra-structure of epidermis and fibroblasts remained normal in 20 % PCF groups; there were vacuoles in smooth endoplasm reticulum in epidermis of mice and the number of rough endoplasm reticulum in fibroblasts was decreased in model group. CONCLUSION: PCF had the protective effects on hairless mice skin damaged by ultraviolet A via its anti-oxidative mechanisms.

Animals↗

PubMed1999

Syp Y279, Y304 Can Mediate the Binding of Bcr-Abl to Grb2 and Other Proteins.

In this study we obtained 3 mutants of Syp cDNA Y279F, Y304F and Y546F by using the method of site-directed mutation in vitro. We then inserted them into the pXM mammalian expression vector, and transferred the plasmids into K562 cells. Western Blot has found WT/ 3MT Syp are expressed in the K562 cells. Immunoprecipitation and Immunoblot have found that WT, Y279F, Y304F and Y546F Syp can bind directly to the Bcr-Abl in vivo. However, we found that mutation of Syp Y279F can block the binding of Grb2 SH2 to Syp mutation of Syp Y304F can block the binding of Shc SH2 to Syp in vitro. As a adaptor, Syp can mediate binding of Bcr-Abl to Shc and Grb2.Grb2 bind to Syp pY279, Shc bind to Syp pY304 in vitro.

Journal Article↗