Search PubMed⌕ Search

Biomedical subjects

Bin Xu

Publications and source records attributed to Bin Xu.

At least 37 records · Page 2Linked to original sources
PubMed2005

Regulation of thyroid hormone receptor alpha2 RNA binding and subcellular localization by phosphorylation.

Thyroid hormone receptor alpha2 (TRalpha2) is an alternative splice product of the TRalpha primary transcript whose unique carboxyl terminus does not bind T3 or activate transcription. The physiological function of TRalpha2 is unknown. We have found that TRalpha2 is a single stranded RNA binding protein and that the RNA binding domain localizes to a 41 amino acid region immediately distal to the second zinc finger. TRalpha2 contains a single protein kinase CK2 phosphorylation site in its amino terminus and potentially nine CK2 sites in its unique carboxyl terminus. In vitro CK2 treatment of TRalpha2 eliminated its RNA binding. Mutational analysis indicated that phosphorylations at the N- and C-terminal sites both contribute to this inhibitory effect. Cellular localization studies demonstrated that phosphorylated TRalpha2 is primarily cytoplasmic, whereas unphosphorylated TRalpha2 is primarily nuclear. Since RNA binding is a property of unphosphorylated TRalpha2, the TRalpha2-RNA interaction likely represents a nuclear function of TRalpha2.

Amino Acids↗
PubMed2005

[Retrograde caudate lobectomy in 7 cases].

OBJECTIVE: To explore the clinical value and significance of retrograde caudate lobectomy. METHODS: From December 2003 to January 2005, 7 patients underwent retrograde caudate lobectomy in which division and ligation of short hepatic veins were carried out at the final stage of the procedure in stead of at the initial stage. RESULTS: The procedures were carried out smoothly with no operative death in all the 7 cases including isolated complete caudate lobectomy in 4 cases, isolated partial caudate lobectomy in 1 case, combined right half liver resection in 2 case. The average operation time, blood loss and length of stay after operation was (273 +/- 44) min, (1114 +/- 241) ml (800-1500 ml) and 16 days respectively. Complications including pleural effusion and ascites in 1 case respectively were fully recovered. During the follow-up, 1 patient died at 6 months for tumor recurrence in lung and the remaining 6 patients are alive at the follow-up of 5 to 16 months. CONCLUSIONS: Retrograde caudate lobectomy is a new procedure suitable for those caudate neoplasms which are adhering to or infiltrating to IVC or too big to move side by side. The application of this technique can converse certain kind of caudate lobe tumor from non-resectable to resectable resulting in widening the indication.

Adult↗
PubMed2005

[The significance of liver hanging maneuver in liver-splitting anterior approach for hepatectomy].

OBJECTIVE: To analyze the feasibility of developing a tunnel between inferior vena cava (IVC) and caudate lobe before passing a tape through it, and to explore the significance of liver hanging maneuver in liver-splitting anterior approach for hepatectomy. METHODS: Blunt dissection was used to develop the tunnel before a tape was passed through. A hemostatic plate was placed on the surface of liver parenchyma if needed. In the procedure of hepatectomy, the tape was pulled up to create an interspace between liver parenchyma and IVC so that the IVC can be protected during transection. RESULTS: Liver hanging maneuver was performed successfully in 47 cases. There were no severe complications related to the procedure in these cases. The procedure was terminated in 1 case because of severe bleeding. CONCLUSIONS: 1. Liver hanging maneuver is feasible in terms of anatomy and technique. 2. With liver hanging maneuver, IVC can be protected safely and the intrahepatic vessels and ductal system at the transaction line can be exposed clearly. It also makes anterior approach for hepatectomy safer and easier.

Adolescent↗
PubMed2005

[The study on immunomodulation of donor mesenchymal stem cells on discordant liver xenotransplantation].

OBJECTIVE: To observe the influence of guinea pig mesenchymal stem cells (MSCs) culture in vitro on the immunological status in heterogeneous recipient, and to evaluate the immunomodulation of MSCs to the immune rejection of liver xenotransplantation. METHODS: The mononuclear cell fraction obtained by centrifugation over Percoll was cultured in vitro. Cell surface epitopes were analyzed by flow cytometry technique, and MSCs were incubated at the addition of adipocyte induction media, and stained in Oil Red O. The immunoglobulin and complement in rat recipient serum were assayed after infusion of donor MSCs. Thirty guinea pigs and thirty Wistar rats were randomly divided into three groups. All rat recipients undertook cyclophosphamide (CTX) infusion. Group A was MSCs infusion group, group B was saline infusion group and group C was dexamethasone (DXM) infusion group. Orthotopic guinea pig to rat liver transplantation model was established. The survival time and the immunopathology of graft were observed. RESULTS: According to flow cytometry assay, MSCs were positive for CD44 and CD29, while negative for CD34 and CD45. Lipid droplets were found in the MSCs cytoplasm after being incubated in adipogenic inducation media. The concentrations of IgG, IgM, C3 at all time point after MSCs infusion were significantly decreased than before (P < 0.05), while the concentrations of IgA and C4 did not changed. The survival time of group A (431 +/- 27 min) was obviously longer than group B (148 +/- 16 min) and group C (141 +/- 22 min) (P < 0.01). The intense hyperacute rejection rapidly occurred of group B and C after blood re-perfusion. The severe immunopathological injury could be observed at the grafts of group B and C. However, the hyperacute rejection of group A occurred slightly. CONCLUSIONS: MSCs can be identified by virtue of cell morphology, membrane phenotype and differential potential. MSC may play a role in the immunosuppression in hyperacute rejection in the liver xenotransplantation.

Animals↗
PubMed2005

Photoluminescence spectral reliance on aggregation order of 1,1-Bis(2'-thienyl)-2,3,4,5-tetraphenylsilole.

1,1-Bis(2'-thienyl)-2,3,4,5-tetraphenylsilole (1) was prepared and characterized crystallographically. Silole 1 exhibited aggregation-induced emission (AIE) behavior like other 2,3,4,5-tetraphenylsiloles. Unexpectedly, aggregates formed in water/acetone (6:4 by volume) mixture emitted a blue light that peaked at 474 nm, while aggregates formed in the mixtures with higher water fractions emitted green light that peaked at 500 nm. Transmission electron microscopy demonstrated that the aggregates formed in the mixture with water fraction of 60% were single crystals, while aggregates that formed in the mixture with water fraction of 90% were irregular and poorly ordered particles. The unusual PL spectral reliance on aggregation order was further confirmed by PL emissions of macroscopic crystal powders and amorphous powders of the silole in the dry state. PL spectral blue shifting was observed upon aging of the poorly ordered aggregates formed in mixtures with water fractions of 70-90%, and they finally exhibited the same blue emission as the crystalline aggregates. The as-deposited thin solid film was amorphous and it could be transformed to a transparent crystalline film upon treatment in the vapor of an ethanol/water (1:1 by volume) mixture, along with PL spectral blue shifting due to changing of aggregation order. It was also found that the crystalline film showed a blue-shifted absorption spectrum relative to the amorphous film and the shift of the absorption edge of the spectra could match that of corresponding PL spectra. The FT-IR spectrum of crystal powders of 1 displayed more vibration modes compared with that of amorphous powders, suggesting the existence of different pi-overlaps or different molecular conformations. The crystals of 1-methyl-1,2,3,4,5-pentaphenylsilole and hexaphenylsilole also showed blue-shifted PL emissions of their amorphous solids, with a comparable PL spectral shift of 1. Developing of a silole solution on a TLC plate readily brought about an amorphous thin layer. Our results suggest that crystalline films of AIE-active siloles are potential emissive layers for efficient blue OLEDs with stable color and long lifetime.

Journal Article↗
PubMed2005

Increased expression in dorsolateral prefrontal cortex of CAPON in schizophrenia and bipolar disorder.

BACKGROUND: We have previously reported linkage of markers on chromosome 1q22 to schizophrenia, a finding supported by several independent studies. Within this linkage region, we have identified significant linkage disequilibrium between schizophrenia and markers within the gene for carboxyl-terminal PDZ ligand of neuronal nitric oxide synthase (CAPON). Prior sequencing of the ten exons of CAPON failed to reveal a coding mutation associated with illness. METHODS AND FINDINGS: We screened a human fetal brain cDNA library and identified a new isoform of CAPON that consists of the terminal two exons of the gene, and verified the expression of the predicted corresponding protein in human dorsolateral prefrontal cortex (DLPFC). We examined the expression levels of both the ten-exon CAPON transcript and this new isoform in postmortem brain samples from the Stanley Array Collection. Quantitative real-time PCR analysis of RNA from the DLPFC in 105 individuals (35 with schizophrenia, 35 with bipolar disorder, and 35 psychiatrically normal controls) revealed significantly (p < 0.005) increased expression of the new isoform in both schizophrenia and bipolar disorder. Furthermore, this increased expression was significantly associated (p < 0.05) with genotype at three single-nucleotide polymorphisms previously identified as being in linkage disequilibrium with schizophrenia. CONCLUSION: Based on the known interactions between CAPON, neuronal nitric oxide synthase (nNOS), and proteins associated with the N-methyl-D-aspartate receptor (NMDAR) complex, overexpression of either CAPON isoform would be expected to disrupt the association between nNOS and the NMDAR, leading to changes consistent with the NMDAR hypofunctioning hypothesis of schizophrenia. This study adds support to a role of CAPON in schizophrenia, produces new evidence implicating this gene in the etiology of bipolar disorder, and suggests a possible mechanism of action of CAPON in psychiatric illness.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Analysis of expressed sequence tags from the venom ducts of Conus striatus: focusing on the expression profile of conotoxins.

Cone snails (genus Conus) are predatory marine gastropods that use venom peptides for interacting with prey, predators and competitors. A majority of these peptides, generally known as conotoxins demonstrate striking selectivity in targeting specific subtypes of ion channels and neurotransmitter receptors. So they are not only useful tools in neuroscience to characterize receptors and receptor subtypes, but offer great potential in new drug research and development as well. Here, a cDNA library from the venom ducts of a fish-hunting cone snail species, Conus striatus is described for the generation of expressed sequence tags (ESTs). A total of 429 ESTs were grouped into 137 clusters or singletons. Among these sequences, 221 were toxin sequences, accounting for 52.1% (corresponding to 19 clusters) of all transcripts. A-superfamily (132 ESTs) and O-superfamily conotoxins (80 ESTs) constitute the predominant toxin components. Some non-disulfide-rich Conus peptides were also found. The expression profile of conotoxins also explained to some extent the pharmacological and physiological reactions elicited by this typical piscivorous species. For the first time, a nonstop transcript of conotoxin was identified, which is suggestive that alternative polyadenylation may be a means of post-transcriptional regulation of conotoxin production. A comparison analysis of these conotoxins reveals the different variation and divergence patterns in these two superfamilies. Our investigations indicate that focal hyper-mutation, block substitution and exon shuffling are three main mechanisms leading to the conotoxin diversity in a species. The comprehensive set of Conus gene sequences allowed the identification of the representative classes of conotoxins and related components, which may lay the foundation for further research and development of conotoxins.

Amino Acid Sequence↗
PubMed2005

Kinetic expression of platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) during embryonic stem cell differentiation.

Platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) is widely used as a marker during vasculogenesis and angiogenesis from embryonic stem (ES) cells. However, the expression of PECAM-1 isoforms in ES cells has not been determined. The present study was designed to determine the role of PECAM-1 isoforms during in vitro endothelial differentiation of ES cells. It was found that undifferentiated ES cells expressed high level of PECAM-1, which primarily located at cell-cell junction, but the expression of PECAM-1 was sharply down-regulated during early ES cell differentiation. In addition, undifferentiated ES cells were found the expressed all eight known alternatively spliced PECAM-1 isoforms, among them the expression of PECAM-1 isoforms lacking exon 15 or 14&15 was predominant. Quantitative analysis revealed a significant increase in the expression of PECAM-1 isoform lacking exon 12&14&15 as vascular development of ES cells. These results indicate a constitutive expression of PECAM-1 in undifferentiated murine ES cells and suggest a developmental role of PECAM-1 isoform changes during vasculogenesis and angiogenesis.

Animals↗
PubMed2005

[Effects of all-trans retinoic acid on expression of connexin genes and gap junction communication in hepatocellular carcinoma cell lines].

OBJECTIVE: To investigate the effect of all-trans retinoic acid (ATRA) on the expression of connexin 26, 32 and 43 genes and the alteration of gap junction communication function in human hepatocellular carcinoma cells. METHODS: Human hepatocellular carcinoma cell of the lines SMMC-7721 and BEL-7404 were cultured in normal medium and medium containing ATRA at a concentration of 10(-5) mol/L for 24, 48 and 72 hours respectively. RT-PCR procedure was adopted to detect the mRNA expression of CX 26, 32 and 43. Scrape-loading and dye transfer procedure was performed to examine the gap junction communication function. RESULTS: CX26 mRNA and CX32 mRNA were not expressed in the cell lines SMMC-7721, however, expression of CX26 mRNA and expression of CX32 mRNA were found 48 and 72 hours after being induction by ATRA respectively. CX26 mRNA and CX32 mRNA were not expressed in the cell lines BEL-7404, however, expression of CX26 mRNA and expression of CX32 mRNA were found 48 hours after induction by ATRA. Expression of CX43 mRNA was found in all cells, whether being induced by ATRA or not. Scrape-loading and dye transfer procedure showed that lucifer yellow was seen in only 1-2 lines by the delimited mark in the untreated SMMC-7721 cells and in 3-4 lines by the delimited mark in the SMMC-7721 cells treated by ATRA. But no dye transfer phenomenon was found in the BEL-7404 cells whether they were ATRA-treated or not. CONCLUSION: ATRA is able to affect the expression of CX26 and CX32 in HCC cell lines SMMC-7721 and BEL-7404 by acting at the transcription level. Reinforcement of gap junction communication function is found in the SMMC-7721 cells and not in the BEL-7404 cells, which shows that ATRA modulates the gap junction intercellular communication, by acting in different mechanisms.

Antineoplastic Agents↗
PubMed2005

NMR and SANS studies of aggregation and microemulsion formation by phosphorus fluorosurfactants in liquid and supercritical carbon dioxide.

(1)H NMR relaxation and diffusion studies were performed on water-in-CO(2) (W/C) microemulsion systems formed with phosphorus fluorosurfactants of bis[2-(F-hexyl)ethyl] phosphate salts (DiF(8)), having different counterions (Na(+), NH(4)(+), N(CH(3))(4)(+)) by means of high-pressure in situ NMR. Water has a low solubility in CO(2) and is mainly solubilized by the microemulsion droplets formed with surfactants added to CO(2) and water mixtures. There is rapid exchange of water between the bulk CO(2) and the microemulsion droplets; however, NMR relaxation measurements show that the entrapped water has restricted motion, and there is little "free" water in the core. Counterions entrapped by the droplets are mostly associated with the surfactant headgroups: diffusion measurements show that counterions and the surfactant molecules move together with a diffusion coefficient that is associated with the droplet. The outer shell of the microemulsion droplets consists of the surfactant tails with some associated CO(2). For W/C microemulsions formed with the phosphate-based surfactant having the ammonia counterion (A-DiF(8)), the (1)H NMR signal for NH(4)(+) shows a much larger diffusion coefficient than that of the surfactant tails. This apparent paradox is explained on the basis of proton exchange between water and the ammonium ion. The observed dependence of the relaxation time (T(2)) on W(0) (mole ratio of water to surfactant in the droplets) for water and NH(4)(+) can also be explained by this exchange model. The average hydrodynamic radius of A-DiF(8) microemulsion droplets estimated from NMR diffusion measurements (25 degrees C, 206 bar, W(0) = 5) was R(h) = 2.0 nm. Assuming the theoretical ratio of R(g)/R(h) = 0.775 for a solid sphere, where R(g) is the radius of gyration, the equivalent hydrodynamic radius from SANS is R(h) = 1.87 nm. The radii measured by the two techniques are in reasonable agreement, as the two techniques are weighted to measure somewhat different parts of the micelle structure.

Journal Article↗
PubMed2005

[Expression of alternatively spliced isoforms of platelet endothelial cell adhesion molecule-1 of embryonic stem cells during vasculogenesis and angiogenesis].

OBJECTIVE: To study the expression of alternatively spliced isoforms of platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) of embryonic stem cells (ES cells) during vasculogenesis and angiogenesis. METHODS: Mouse ES cells of the line J1 were cultured. Another ES cells were cultured in differentiation medium to induce the formation of embryonic bodies (EBs). Then the ES cells with PECAM-1 and EBs were inoculated with methylcellulose into Petri dish, containing cell growth factor, VEGF, bFGF, EPO, and IL-6 and the ES cells cultured for 11 days were inoculated in the Petri dish with collagen for 72 hours so as to induce sprouting angiogenesis. Immunofluorescence analysis, RT-PCR, and flow cytometry were used to detect the expression of PECAM-1, Oct-4, and stage-specific embryonic antigen (SSEA)-1 in the undifferentiated ES cells, EBs, and EB sprouting. In order to delineate the alternatively spliced cytoplasmic domain isoforms of PECAM-1 specific primers were designed to span the exon-exon junctions in the regions of alternative splicing. In order to amplify the cytoplasmic domains of all possible PECAM-1 isoforms a sense primer spanning the border of exons 9 and 10 within the cytoplasmic domain and an antisense primer spanning the border of exon 16 and 3'-untranslated region were used. Then the PCR products of the cytoplasmic domain underwent subsequent sequencing to analyze the expression of the 8 known alternatively splice isoforms of PECAM-1. RESULTS: The ES cells expressed high level PECAM-1 that was mainly located at the cell-cell junctions. The SSEA-1 and Oct-4 levels rapidly decreased along with the differentiation of the ES cells. All 8 known alternatively splice isoforms of PECAM-1 were expressed in the ES cells and the EB sprouting, the expression of Delta14%15 and Delta12&14&15 being the highest. The expression level of Delta12&14&15 increased markedly and the expression of Delta15 decreased along with the differentiation of ES cells. CONCLUSION: PECAM-1 is a constitutive feature of undifferentiated ES cells. Its changes in splice form mark the differentiation and may participate in vasculogenesis and angiogenesis.

Alternative Splicing↗
PubMed2005

Diabetes-associated mutations in human insulin: crystal structure and photo-cross-linking studies of a-chain variant insulin Wakayama.

Naturally occurring mutations in insulin associated with diabetes mellitus identify critical determinants of its biological activity. Here, we describe the crystal structure of insulin Wakayama, a clinical variant in which a conserved valine in the A chain (residue A3) is substituted by leucine. The substitution occurs within a crevice adjoining the classical receptor-binding surface and impairs receptor binding by 500-fold, an unusually severe decrement among mutant insulins. To resolve whether such decreased activity is directly or indirectly mediated by the variant side chain, we have determined the crystal structure of Leu(A3)-insulin and investigated the photo-cross-linking properties of an A3 analogue containing p-azidophenylalanine. The structure, characterized in a novel crystal form as an R(6) zinc hexamer at 2.3 A resolution, is essentially identical to that of the wild-type R(6) hexamer. The variant side chain remains buried in a nativelike crevice with small adjustments in surrounding side chains. The corresponding photoactivatable analogue, although of low affinity, exhibits efficient cross-linking to the insulin receptor. The site of photo-cross-linking lies within a 14 kDa C-terminal domain of the alpha-subunit. This domain, unrelated in sequence to the major insulin-binding region in the N-terminal L1 beta-helix, is also contacted by photoactivatable probes at positions A8 and B25. Packing of Val(A3) at this interface may require a conformational change in the B chain to expose the A3-related crevice. The structure of insulin Wakayama thus evokes the reasoning of Sherlock Holmes in "the curious incident of the dog in the night": the apparent absence of structural perturbations (like the dog that did not bark) provides a critical clue to the function of a hidden receptor-binding surface.

Amino Acid Sequence↗
PubMed2005

Expression and significance of heparanase and nm23-H1 in hepatocellular carcinoma.

AIM: To explore the relation between heparanase (HPA) and nm23-H1 in hepatocellular carcinoma (HCC), and whether they could be used as valuable markers in predicting post-operative metastasis and recurrence of HCC. METHODS: Reverse transcription-polymerase chain reaction and immunohistochemistry (S-P method) were used to measure the expressions of HPA mRNA and nm23-H1 protein in primary tumor tissue and paracancerous tissue of 33 cases of HCC. Paracancerous tissues of 9 cases of benign liver tumor were used as normal controls. The results were analyzed in combination with the results of clinicopathological examination and follow-up. RESULTS: The positive expression of HPA gene was significantly higher in primary tumor tissues of HCC (48.5%, 16/33) as compared to the paracancerous tissues of HCC and normal controls (3.03%, 1/33) (P < 0.01). HPA expression was not related with the size of tumor, envelope formation, AFP level, HBsAg state and cirrhosis of liver. The positive rates of HPA mRNA in the group with high tendency to metastasis or recurrence and in the group with metastasis or recurrence during the follow-up were significantly higher than those in the group with low tendency to metastasis or recurrence (62.5% vs 37.5%, P < 0.05) and in the group without metastasis or recurrence (78.6% vs 21.4%, P < 0.01). The poorly differentiated tumor and tumor of TNM stages III-IV had a higher positive rate of HPA gene expression than the well differentiated tumor and tumor of TNM stages I-II (66.7% vs 33.3%, P < 0.05). The positive expression rate of nm23-H1 protein in HCC tissue was significantly lower than that in corresponding non-cancerous or normal liver tissue (45.5, 72.7, 88.9%, P < 0.05). nm23-H1 expression was not related with the size of tumor, envelope formation, AFP level, HBsAg state, cirrhosis of liver, Edmondson grade, and TNM stage (P > 0.05). The positive rates of nm23-H1 in the group with high tendency to metastasis and recurrence and in patients with metastasis or recurrence during the follow-up were obviously higher than those in the group with low tendency to metastasis and recurrence (P = 0.018) and in the patients without metastasis and recurrence (P = 0.024); but no significant difference was found between HPA positive and negative groups (P = 0.082). According to the results of follow-up, the rate of accuracy in predicting metastasis of positive HPA, negative nm23-H1 and combination of positive HPA with negative nm23-H1 was 78.6% (11/14), 68.8% (11/16) and 88.9% (8/9), respectively. CONCLUSION: Expression of HPA and/or nm23-H1 is related with metastasis and recurrence of HCC. Detection of the expression rate of HPA and nm23-H1 may help increase the accuracy in predicting post-operative metastasis and recurrence of HCC.

Adult↗
PubMed2005

[Surgical treatment of hepatocellular carcinoma originating from caudate lobe].

OBJECTIVE: To explore the significance of surgical treatment of HCC originating from caudate lobe. METHODS: From 1995 to 2003, caudate lobectomy, including 19 cases of isolated lobectomy and 20 cases of combined lobectomy, were performed in 39 patients with HCC originating from caudate lobe, and the factors that might influence postoperative liver function were compared between the two groups. RESULTS: All tumors were resected successfully. One patient died of postoperative renal failure. Hydrothorax occurred in 3 patients, ascites in 4 patients, and bile leakage in 1 patient. The survival rates of 1, 3, 5 year were 53%, 50%, 39% respectively. CONCLUSIONS: Caudate lobectomy is a effective method for HCC originating from caudate lobe.

Adult↗
PubMed2005

An inverse methodology for high-frequency RF coil design for MRI with de-emphasized B1 fields.

An inverse methodology for the design of biologically loaded radio-frequency (RF) coils for magnetic resonance imaging applications is described. Free space time-harmonic electromagnetic Green's functions and de-emphasized B1 target fields are used to calculate the current density on the coil cylinder. In theory, with the B1 field de-emphasized in the middle of the RF transverse plane, the calculated current distribution can generate an internal magnetic field that can reduce the central overemphasis effect caused by field/tissue interactions at high frequencies. The current distribution of a head coil operating at 4 T (170 MHz) is calculated using an inverse methodology with de-emphasized B1 target fields. An in-house finite-difference time-domain routine is employed to evaluate B1 field and signal intensity inside a homogenous cylindrical phantom and then a complete human head model. A comparison with a conventional RF birdcage coil is carried out and demonstrates that this method can help in decreasing the normal bright region caused by field/tissue interactions in head images at 170 MHz and higher field strengths.

Brain↗
PubMed2005

Bone marrow stromal cells transduced with human hemangiopoietin gene support hematopoiesis in vitro.

BACKGROUND AND OBJECTIVES: The aim of this study was to construct a eukaryotic expression vector containing human hemangiopoietin (hHAPO) gene and express it in mouse bone marrow stromal cell line HESS-5, then support hematopoiesis in vitro with gene-modified HESS-5 (hHAPO-HESS-5). DESIGN AND METHODS: The polymerase chain reaction (PCR) products of HAPO were digested with BamHI and BgII. Then the HAPO gene segment obtained was again cloned into pIRES2-EGFP to construct recombinant eukaryotic expression vector HAPO-pIRES2-EGFP. The recombinant vector was identified by enzyme digestion analysis, PCR, and sequencing. HESS-5 cells were transformed by recombinant vector and positive clones were selected with G418. The expression of HAPO gene in the transformed cells was detected by studying EGFP expression, reverse transcription (RT)-PCR, and Western-blotting analysis. Support of human hematopoiesis by hHAPO-HESS-5 cells was evaluated in co-culture experiments with human CD34+ cells. RESULTS: Enzyme digestion analysis and sequencing showed that the target gene had been cloned into the recombinant vector. The expression of HAPO gene in the transformed stromal cells was demonstrated by fluoro-microscopy and RT-PCR analysis. HAPO protein was also detected in the supernatant of hHAPO-HESS-5 by Western blot analysis. As expected, stably transfected hHAPO-HESS-5 cells significantly increased in both relative and absolute numbers of CD34+ cells after 14 days of culture. The PKH26 study demonstrated that cell division was faster in CD34+ cells co-cultured with hHAPO-HESS-5 cells than in cells cocultured with vector-HESS-5 cells. The hHAPO-HESS-5 cells also supported human hematopoiesis in vitro more efficiently than did control vector-HESS-5 cells. INTERPRETATION AND CONCLUSIONS: A recombinant eukaryotic expression vector has been constructed and expressed successfully in transformed cells. The hHAPO-HESS-5 cells support rapid generation of primitive progenitor cells and maintain reconstituting ability of hematopoietic stem cells in vitro. Therefore, it would be possible to use stromal cells expressing HAPO gene as seed cells in the bone marrow transplantation.

Angiopoietins↗
PubMed2005

[Biomechanical study of rigid fixation of the maxillofacial fractures].

Due to the ascending incidence rate of traffic trauma, more and more fractures in oral and maxillofacial region were encountered, which become more severe than before and damage the patient's quality of life and appearance. Biomechanical principles play an extremely important role in treatment of fractures,and study of biomechanical changes of fractured bone before and after rigid internal fixation will improve the effectiveness of therapy. The author summarized the biomechanical studies in the field of rigid internal fixation of fractures in oral and maxillofacial region.

Biomechanical Phenomena↗