PubMed Health⌕ Search

Biomedical subjects

Xue Feng

Publications and source records attributed to Xue Feng.

At least 19 recordsLinked to original sources
PubMed2006

Engineering of human tracheal tissue with collagen-enforced poly-lactic-glycolic acid non-woven mesh: a preliminary study in nude mice.

The purpose of the current study is to fabricate tissue engineered trachea with poly-lactic-glycolic acid (PLGA) non-woven mesh enforced by collagen type I. PLGA fibres coated with collagen solution were put together and fabricated into the shape of a human trachea, after drying and cross-linking treatment, a non-woven mesh with "C" shape formed. Chondrocytes from sheep nasal septum cartilage were expanded in vitro and seeded into PLGA/collagen non-woven mesh in the density of 5.0 x 10(7)mL(-1). After 5 days of in vitro incubation, six Cell-PLGA/collagen composites were implanted subcutaneously into the back of 6 nude mice to prefabricate a tissue engineering trachea. Eight weeks later, the cartilage formation was observed by gross inspection and histological examination. Cartilage-like tissue in the shape of the initial PLGA/collagen scaffold had been regenerated successfully without obvious inflammatory response. The tissue engineered trachea cartilage consisted of evenly spaced lacunae embedded in matrix stained red with safranin-O staining. The amount of GAGs in tissue engineered trachea cartilage reached 71.42% of normal value in native cartilage. This study demonstrated that collagen-enforced PLGA non-woven mesh facilitated the adhesion and proliferation of chondrocytes, it also owned adequate mechanical strength to serve as an ideal scaffold for trachea tissue engineering without internal support.

Animals↗
PubMed2006

Regularized inversion method for retrieval of aerosol particle size distribution function in W(1,2) space.

A determination of the aerosol particle size distribution function by using the particle spectrum extinction equation is an ill-posed integral equation of the first kind. To overcome this, we must incorporate regularization techniques. Most of the literature focuses on the Phillips-Twomey regularization or its variations. However, there are drawbacks for some applications in which the real aerosol distributions have large oscillations in a Junge-type distribution. The reason for this is that the scale matrix based on the norm of the second differences in the Phillips-Twomey regularization is too ill- conditioned to filter the large perturbations induced by the small algebraic spectrum of the kernel matrix and the additive noise. Therefore we reexamine the aerosol particle size distribution function retrieval problem and solve it in W1,2 space. This setting is based on Sobolev's embedding theorem in which the approximate solution best simulates the true particle size distribution functions. For choosing the regularization parameters, we also develop an a posteriori parameter choice method, which is based on the discrepancy principle. Our numerical results are based on the remote sensing data measured by the CE318 sunphotometer in Jia Xiang County, Shan Dong Province, China, and are performed to show the feasibility of the proposed algorithms.

Journal Article↗
PubMed2006

The FoxM1 transcription factor is required to maintain pancreatic beta-cell mass.

The FoxM1 transcription factor is highly expressed in proliferating cells and activates several cell cycle genes, although its requirement appears to be limited to certain tissue types. Embryonic hepatoblast-specific inactivation of Foxm1 results in a dramatic reduction in liver outgrowth and subsequent late gestation lethality, whereas inactivation of Foxm1 in adult liver impairs regeneration after partial hepatectomy. These results prompted us to examine whether FoxM1 functions similarly in embryonic outgrowth of the pancreas and beta-cell proliferation in the adult. We found that FoxM1 is highly expressed in embryonic and neonatal endocrine cells, when many of these cells are proliferating. Using a Cre-lox strategy, we generated mice in which Foxm1 was inactivated throughout the developing pancreatic endoderm by embryonic d 15.5 (Foxm1(Deltapanc)). Mice lacking Foxm1 in their entire pancreas were born with normal pancreatic and beta-cell mass; however, they displayed a gradual decline in beta-cell mass with age. Failure of postnatal beta-cell mass expansion resulted in impaired islet function by 6 wk of age and overt diabetes by 9 wk. The decline in beta-cell mass in Foxm1(Deltapanc) animals is due to a dramatic decrease in postnatal beta-cell replication and a corresponding increase in nuclear localization of the cyclin-dependent kinase inhibitor, p27(Kip1), a known target of FoxM1 inhibition. We conclude that Foxm1 is essential to maintain normal beta-cell mass and regulate postnatal beta-cell turnover. These results suggest that mechanisms regulating embryonic beta-cell proliferation differ from those used postnatally to maintain the differentiated cell population.

Animals↗
PubMed2006

Effect of 5-azacytidine on the protein expression of porcine bone marrow mesenchymal stem cells in vitro.

Bone marrow-derived mesenchymal stem cells (MSCs) are pluripotent stem cells that show a vital potential in the clinical application for cell transplantation. In the present paper, proteomic techniques were used to approach the protein profiles associated with porcine bone marrow MSCs and investigate the regulation of MSC proteins on the effect of 5-azacytidine (5-aza). Over 1,700 protein species were separated from MSCs according to gel analysis. Compared with the expression profiling of control MSCs, there were 11 protein spots up-regulated and 26 down-regulated in the protein pattern of 5-aza-treated cells. A total of 21 proteins were successfully identified by MALDI-TOF-MS analysis, among which some interesting proteins, such as alpha B-crystallin, annexin A2, and stathmin 1, had been reported to involve in cell proliferation and differentiation through different signaling pathways. Our data should be useful for the future study of MSC differentiation and apoptosis.

Animals↗
PubMed2006

[Genetic polymorphism of six short tandem repeat loci on the X chromosome in a Han race population in China].

OBJECTIVE: To investigate the alleles and genotype frequencies of 6 short tandem repeat (STR) loci DXS7130, DXS1214, DXS6799, DXS6804, DXS7424 and DXS7133 on the X chromosome in Chinese Han individuals living in Shaanxi province of Northwest China. METHODS: The 6 X-chromosomal STR loci were typed by PCR, denatured polyacylamide gel electrophoresis and silver stain. RESULTS: Among females from Xi'an Han population, the numbers of alleles in the 5 loci (DXS7130, DXS6799, DXS6804, DXS7424 and DXS7133) were detected to be 9, 6, 6, 7, and 7 respectively; the numbers of genotypes were 21, 14, 15, 17 and 12 respectively; and the number of alleles in the DXS1214 was 8. Exact tests demonstrated that genotype frequencies of females had no departure from Hardy-Weinberg equilibrium. CONCLUSION: The six loci of X-chromosomal STRs are appropriate for individual identification, paternity test involving in female child and for study in related disease.

Asian People↗
PubMed2006

[An investigation for genetic polymorphisms of 10 STR loci on chromosome X of Chinese Hui nationality population in Ningxia region of China].

OBJECTIVE: To investigate the alleles and genotypes frequency of 10 short tandem repeat (STR) loci (DXS101, DXS6789, DXS6799, DXS6804, DXS7130, DXS7132, DXS7133, DXS7423, HPRTB, DXS8378) on X chromosome of Chinese Hui nationality population. METHODS: The study of 10 STR loci was performed by using the techniques of PCR, polyacylamide gel electrophoresis and silver staining. RESULTS: Among unrelated Hui individuals, the allele numbers of 10 STR loci DXS101, DXS6789, DXS6799, DXS6804, DXS7130, DXS7132, DXS7133, DXS7423, HPRTB, DXS8378 were 9, 8, 4, 6, 6, 6, 4, 4, 5 or 5 respectively; the numbers of genotypes were 17, 22, 7, 14, 14, 15, 6, 7, 12 or 8 respectively. The distribution of genotypes from these 10 STR systems fitted the Hardy-Weinberg equilibrium (P> 0.05). Polymorphisms information content of 10 STR loci, except for DXS7133 (0.48) and DXS7423 (0.48), ranged from 0.54 (DXS6799) to 0.80 (DXS6789); the power of discrimination were from 0.89 (DXS7133, DXS7423) to 0.99 (DXS6789, DXS7132, DXS101). CONCLUSION: The loci of 10 STR on chromosome X are appropriate for individual identification, paternity testing involving a female child and for study on related disease.

Alleles↗
PubMed2005

Experimental investigation of an inhomogeneous loss and its influence on multiwavelength fiber lasers.

Inhomogeneous loss generated by multimode laser linewidth broadening in an optical fiber is experimentally studied. With this mechanism, multiwavelength lasing is achieved by use of either fiber Raman gain or erbium-doped fiber gain. Through various pump powers and optical filter bandwidths, the relationship between inhomogeneous loss and the performance of a multiwavelength fiber laser is studied, and a physical explanation is provided.

Journal Article↗
PubMed2005

Sensitivity of ammonia interaction with single-walled carbon nanotube bundles to the presence of defect sites and functionalities.

Ammonia adsorption on single-walled carbon nanotubes (SWNTs) was studied by means of infrared spectroscopy at both cryogenic (approximately 94 K) and room (approximately 300 K) temperatures. At 94 K, vacuum-annealed SWNTs showed no detectable ammonia uptake. However, the ammonia adsorption was found to be sensitive to the functionalities and defects on the nanotube surfaces. NH3 adsorption was detected on HNO3-treated nanotubes, characterized by significant functionalities and defects, prior to vacuum annealing. NH3 desorbed from those nanotubes above 140 K, indicating a weak adsorbate-nanotube interaction (approximately 30 kJ/mol). Exposure of annealed samples to ambient air, which possibly regenerated functionalities and defects on nanotube surfaces, restored partially the ammonia uptake capacity. No ammonia adsorption on SWNTs was observed by infrared spectroscopy at room temperature with up to 80 Torr dosing pressure. This work suggests the influence of functionalities and/or defect densities on the sensitivity of SWNT chemical gas sensors. Our theoretical studies on NH3 adsorption on pristine and defective tubes, as well as oxidized tubes, corroborate these findings.

Journal Article↗
PubMed2005

Inhomogeneous loss mechanism in multiwavelength fiber Raman ring lasers.

As one of the mechanisms for stable multiwavelength oscillation in a fiber Raman ring laser, an inhomogeneous loss induced by intraline four-wave mixing in a fiber Raman laser is physically explained and experimentally validated by comparison of laser peak gain and power gain as well as the gain spectra at several pump levels.

Journal Article↗
PubMed2005

Anchoring dental implant in tissue-engineered bone using composite scaffold: a preliminary study in nude mouse model.

PURPOSE: The purpose of this study was to fabricate a tissue-engineered bone graft anchoring dental implant with bone marrow stromal cell (bMSC) seeded coral-implant composite scaffold. MATERIALS AND METHODS: Titanium dental implants (3 mm in diameter) were inserted into the cylinder coral scaffolds (5 mm in diameter and 1 mm in wall thickness). bMSCs were isolated from iliac bone marrow of adult New Zealand White rabbits, induced by dexamethasone and seeded into the composite scaffold at the density of 2 x 10 8 /mL in 200 muL medium. Nine cell coral-implant complexes were incubated in vitro for 5 days. One complex was processed for scanning electronic microscopy. The other 8 complexes, together with 4 coral scaffold without cell acting as control, were implanted subcutaneously into nude mice back. At 1 and 2 months after implantation, 4 specimens from the experiment group and 2 specimens from the control group were harvested respectively. New bone restoration and new bone integration with dental implant were evaluated by gross inspection, manual handling test, radiographic examination, and histologic observation. RESULTS: Specimens harvested at 2 months after implantation were red and similar to native bone. Manual handling test showed that dental implants were fixed in the newly formed bone. Radiographic examination showed that most of the coral scaffold had been absorbed. Bone density x-ray shadow could be observed around the dental implant. Histologic examination showed that large amount of new bone formed around the dental implants and integrated well with the implants in some area. In the control group no bone formation was observed both macroscopically and microscopically. CONCLUSION: The results of the study suggested that the tissue-engineered bone of bMSCs seeded natural coral-implant composite scaffold is promising for dental implant anchoring, which has positive implication for clinical jaw reconstruction.

Animals↗
PubMed2005

[Evaluation of biological safety of continuous carbon-fiber reinforced polyolefin as hard tissue repair].

OBJECTIVE: To evaluate the biological safety of continuous carbon-fiber reinforced polyolefin as hard tissue repair material. METHODS: Biocompatibility of the material was evaluated through hemolysis test, pyrogen test, skin irritation test, cytotoxicity test, ames test, in vitro chromosome aberration test, and bone marrow cells Micronuclei test. RESULTS: No obvious hemolysis, pyrogenic characteristics, sensitivity, cytotoxicity, and mutagenicity were observed. CONCLUSION: The continuous carbon-fiber reinforced polyolefin composite material is of good biological safety. It meets all the demand made by biological safety as hard tissue repair material.

Animals↗
PubMed2005

[Genetic polymorphism of Y-chromosome short tandem repeat in Elunchun ethnic group of China].

OBJECTIVE: To reveal the allelic frequencies and haplotype frequencies of ten Y-chromosome short tandem repeats(STR) loci (DYS392, DYS438, DYS439, DYS456, DYS459, DYS460,DYS461, DYS462, DYS389I and DYS389II systems) in an Elunchun population sample. METHODS: PCR and polyacrylamidegel electrophoresis(PAGE) followed by silver staining were performed to analyze the blood samples from 102 unrelated Elunchun male individuals. RESULTS: The allele diversity values for each locus ranged from 0.418(DYS461) to 0.727(DYS389 I). Gene diversities were higher than 0.5 except DYS462(0.479) and DYS461 (GATAA7.2)(0.418). Furthermore, 101 haplotypes from 10 Y-chromosome STRs loci were found in the sample and a high haplotype diversity 0.99 was determined. CONCLUSION: The above findings suggest that the ten Y-chromosome STR loci are valuable Y-specific markers for establishing Y-STR database, understanding human origin, paternity testing and personal identification.

China↗
PubMed2004

A microfluidic device based on gravity and electric force driving for flow cytometry and fluorescence activated cell sorting.

A novel method based on gravity and electric force driving of cells was developed for flow cytometry and fluorescence activated cell sorting in a microfluidic chip system. In the experiments cells flowed spontaneously under their own gravity in a upright microchip, passed through the detection region and then entered into the sorting electric field one by one at an average velocity of 0.55 mm s(-1) and were fluorescence activated cell sorted (FACS) by a switch-off activation program. In order to study the dynamical and kinematic characteristics of single cells in gravity and electric field of microchannels a physical and numerical module based on Newton's Law of motion was established and optimized. Hydroxylpropylmethyl cellulose (HPMC) was used to minimize cell assembling, sedimentation and adsorption to microchannels. This system was applied to estimate the necrotic and apoptotic effects of ultraviolet (UV) light on HeLa cells by exposing them to UV radiation for 10, 20 or 40 min and the results showed that UV radiation induced membrane damage contributed to the apoptosis and necrosis of HeLa cells.

Apoptosis↗
PubMed2004

Marrow-derived osteoblasts seeded into porous natural coral to prefabricate a vascularised bone graft in the shape of a human mandibular ramus: experimental study in rabbits.

To find out if it was possible to prefabricate bone graft in the shape of a human mandibular ramus that possessed a pedicle that carried blood. The pore size of the natural coral was about 200 microm with a porosity of about 36%. The natural coral was made into the shape of a human mandibular ramus. Marrow-derived osteoblasts were seeded into porous natural coral scaffolds in a density of 2 x 10(8)/mL in 300 microL cell suspension. After two days of in vitro incubation, five cell-coral complexes were implanted into cell donor rabbits under the inferior epigastric blood vessels to prefabricate a vascularised bone graft of specific shape. Two months later the bone formation was observed by gross inspection and histological examination. Two months after operation, a well-vascularised bone graft in the shape of the initial coral scaffold and with a blood-carrying pedicle had been regenerated successfully. Osteogenesis followed the pattern of endochondral bone formation. New bone could be seen on the surface and in the pores of coral on histological examination. We have shown that it is possible to fabricate vascularised bone graft in a predetermined shape using tissue engineering. This kind of bone graft may have future clinical application.

Animals↗
PubMed2004

[Cloning genes sensitive to mechanical stretch in osteoblasts through subtractive hybridization technique].

OBJECTIVE: In this experiment, genes sensitive to mechanical stretch in osteoblast like cells were cloned through subtractive hybridization technique. METHODS: Two dimensional mechanical stretch with deformation of 12% and frequency of 6 cycles was loaded on human osteoblastic like cell line Saos-2. Complementary deoxyribonucleic acid (cDNA) library of cells was constructed 12 h after loading, acting as tester. cDNA library of cells without loading was constructed, acting as driver. A subtractive cDNA library osteoblastic like cell stimulated with mechanical stretch was constructed through subtractive hybridization technique. RESULTS: Of clones randomly selected from this library, fifteen genes were identified to be the differentially expressed genes. Comparing with the sequences published in GeneBank via Internet, two sequences located in chromosome 9 and 18 respectively were identified to be novel, which were named as stretch sensitive gene 1 and stretch sensitive gene 2. CONCLUSION: It is an efficient approach to clone and study genes relative to mechanical stretch through subtractive hybridization technique.

Cell Line↗
PubMed2003

[Effect of elastic stress on expression of corebinding factor a 1 mRNA in human periodontal ligament cells in vitro].

OBJECTIVE: To investigate the osteoblast-like characteristics of human periodontal ligament cells affected by elastic stress in vitro, and the role of corebinding factor a 1 (cbfa1) in alveolar bone formation during orthodontic tooth movement. METHODS: Rat dig-labeled cbfa1 cDNA probe was prepared from SD rat osteoblasts cultured in vitro. Human periodontal ligament cells were cultured on the elastic bottom plate and stimulated by elastic stress using mechanical loading system for cultured cells in vitro. The expression of cbfa1 mRNA was detected by in situ hybridization method. RESULTS: Cbfa1 mRNA express in human periodontal ligament cells stimulated by elastic stress and did not express in normal human periodontal ligament cells. CONCLUSION: It is suggested that elastic stress plays a role in the differentiation process from human periodontal ligament cells to osteoblast-like cells. Cbfa1 is a transcription factor in alveolar bone remodeling during orthodontic tooth movement.

Adolescent↗
PubMed2002

Adjusted active carbon fibers for solid phase microextraction.

Adjusted active carbon fiber (AACF) was evaluated for Solid Phase Microextraction (SPME), which showed higher sensitivity and stability than traditional coating fibers. The characteristics of AACF result from two different activation methods (chemical and water vapor) and from variable activation conditions (temperature and time). The fiber treated by water vapor appears to have stronger affinity to polar compounds, while that treated by chemical activation appears to have stronger affinity to non-polar compounds. For different target compounds ranged from non-polar to polar, AACF design could be effective with specific selections and sensitivities. As applications in this paper, benzoic acid in soy sauce was extracted onto water-vapor-activated-fiber, then analyzed using gas chromatograph-mass spectrometer (GC-MS). The chemical-activated-fiber SPME was applied in the analysis of benzene series compounds (BTEX) in water matrix. Compared with standard carbon disulfide extraction method, chemical-activated-fiber SPME is more convenient due to its simple process and turns to be of relative low detection limits.

Carbon↗