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Yan Xu

Publications and source records attributed to Yan Xu.

At least 73 records · Page 4Linked to original sources
PubMed2006

[Related factors affecting the isolation of multipotent non-hematopoietic adult stem cells from umbilical cord blood].

To investigate the related factors affecting the isolation of multipotent non-hematopoietic adult stem cells (MNASCs) from human umbilical cord blood in low serum (2%) condition, the isolation conditions were optimized and the yield of MNASCs was improved. MNASCs from human umbilical cord blood samples were isolated, and the effects of medium component, medium exchange time and initial plating density for isolation of MNASCs were studied. Then, the MNASCs were isolated and cultured in optimal condition, the surface antigen expression and differentiation potential of MNASCs were detected. The result showed that the medium of DMEM/F12 was better than IMDM and DMEM-LG for MNASCs culture in low serum condition. The optimal yield of MNASCs was obtained when mononuclear cells were cultured at a initial plating density of 1 x 10(6) cells/cm2 and the medium was exchanged to remove the nonadherent cells after 72 hours of inoculation. MNASCs isolated and cultured under the above-mentioned conditions maintained a homogenous morphology, high potential ability of expansion and differentiation. It is concluded that culture conditions with low serum defined in this study is optimal for the successful isolation and expansion of umbilical cord blood MNASCs with high numbers for subsequent cellular therapeutic approaches.

Cell Culture Techniques↗
PubMed2006

[Preparation and structural characterization of ZnTHPP/TiO2 hybrid material].

Using sol-gel method to make tetra-meso (hydroxylphenyl) zinc porphyrin (ZnTHPP) trapped in inorganic networks of TiO2, a new organic/inorganic hybrid material was prepared. The structures and morphology of this material were characterized by thermogravimetric analyses (TGA), infrared spectrum (FTIR), UV-Vis spectrum (UV), diffuse reflectance spectroscopy (DRS), and scanning electron microscopy (SEM), indicating that ZnTHPP/TiO2 hybrid material possessed excellent thermostability, and ZnTHPP was trapped in TiO2 network with chemical bonds. In addition, ZnTHPP embedding can enlarge the absorption range of light for TiO2 effectivelly.

English Abstract↗
PubMed2006

[Autologous versus allogeneic stem cell transplantation in adult patients with acute lymphoblastic leukemia].

OBJECTIVE: To explore the efficacy of autologous or allogeneic stem cell transplantation in adult patients with acute lymphoblastic leukemia (ALL) and investigate its relevant prognostic factors. METHODS: A total of 96 adult patients with ALL who had admitted to our hospital from November 1986 to June 2004 were followed up till February 28, 2005. They were divided into autologous stem cell transplantation (Auto-SCT) group (n = 56) and allogeneic stem cell transplantation (Allo-SCT) group (n = 40). Auto-SCT group was further divided to treated subgroup, in which patients received graft-purified transplantation and (or) maintenance immunotherapy or chemotherapy after transplantation (n = 26), and non-treated subgroup (n = 30). Clinical characteristics of these groups were retrospectively analyzed. Survival date were analyzed by the Kaplan-Meier method and the prognostic factors were analyzed with the COX regression model. RESULTS: The 1-, 3-, and 5-year leukemia-free-survival (LFS) were not significantly different between the auto-SCT group and the allo-SCT group. The 3-and 5-year LFS of auto-SCT treated subgroup, auto-SCT non-treated subgroup and allo-SCT group were [(73.0 +/- 8.7)%, (69.2 +/- 9.0)%], [(42.2 +/- 10.1)%, (35.1 +/- 10.0)%], and [(50.9 +/- 8.2)%, (50.9 +/- 8.2)%], respectively, which showed statistical significance (P < 0.05). CONCLUSIONS: The long-term LFS is similar after auto-SCT and after allo-SCT. Purified graft and maintain immunotherapy or chemotherapy post-transplantation may decrease the relapse rate after auto-SCT and improve survival.

Adolescent↗
PubMed2006

[Design and implementation of a medical record management subsystem as a part of a telemedical system].

This paper introduces the work on the design and implementation of a medical record management subsystem, which is a part of a telemedicine system based on Microsoft .NET. First, an analysis is given on components and structure of medical record, together with an explanation for what is needed in a teleconsultation, how they should be organized and realized in a database, and how to deal with consultation data granularity using XML in combination with database; second, the work done during the realization stage is expatiated, including system analysis and design, database design, and system implementation.

Database Management Systems↗
PubMed2006

[The expression of HIF-1 in the early diabetic NOD mice].

PURPOSE: To study the retinal expression of HIF-1 alpha in the diabetic NOD mice. METHODS: NOD mice were divided into normal control group and diabetes group randomly, sacrificed at 2, 4, 6, 8 or 12 weeks. Eyes were enucleated and retinas were isolated and used for western blot, or eyes were sectioned for immunohistochemical staining for HIF-1 alphal. RESULTS: Compared to the normal control group, blood sugar of diabetes mice increased significantly but the weights decreased significantly (P < 0.01). Western blot of retinal lysates showed low levels of HIF-1 alpha at the 6th weeks that were markedly increased at the 12th weeks in the diabetes group. Immunohistochemistry showed increased staining for HIF-1 in the inner retina, but not in the outer retina. CONCLUSION: The retinal HIF-1 alpha levels increasing showed that retinal ischemia happening in the early diabetes. HIF-1 alpha may participate in the secondary damage of retinal ischemia induced by early diabetes.

Animals↗
PubMed2006

[Design and implementation of an intellectualized measuring instrument for medical electricity security parameters].

An introduction of an intelligent testing instrument for medical electrical equipment security is given in this article. The realization of its testing functions is based on a single-chip processor, the high-voltage control circuit and the relay combination network technology. It can be used to test security parameters such as the continuous leakage current, patient auxiliary current, dielectric strength and protective earth impedance. It is suitable for the medical electricity security testing of Kind I, II and Type B, BF, CF (internal power supply) medical electrical equipments.

Electricity↗
PubMed2006

[New option for gene-targeting vector construction Red/ET recombination].

The study of human new gene's function has become an increasingly active academic field basically relying on the gene knockout (KO) mouse. The construction of targeting vector economically and efficiently has turned into the key step to acquire a KO mouse because of the low efficiency of recombination with traditional constructed targeting vector. For study of the function of new gene-Resp18, we brought in a new DNA engineering platform-Red/ET recombination to construct Resp18 targeting vector. Red/ET recombineering differs from the conventional ways of vector construction (e.g., PCR, restriction enzyme digestion and ligation) and achieves genetic modification by acquisition, insertion, fusion or replacement of the target gene through small fragments mediated homologous recombination. Now Resp18 targeting vectors of three strategies were yielded successfully through two homologous recombination processes of retrieve and neo-targeting. Red/ET recombination has the advantage of getting longer homology regions without mutation, which makes it a new and reliable alternative to the construction of a targeting vector today.

Bacteriophage lambda↗
PubMed2006

[Comparison of expanding dendritic cells derived from cord blood and mobilized peripheral blood by two-step culture method].

To compare the expansion efficiency and function of dendritic cells derived from CB-CD34+ cells and MPB-CD34+ cells by using two-step culture method, enriched CB-CD34+ cells or MPB-CD34+ cells with immunoadsorption were primarily cultured in the presence of FL, SCF, TPO, GM-CSF for 10 days, and then further cultured with a combination of GM-CSF, IL-4, TNF-alpha, CD40Ab and PGE2 to induce DC. The DC phenotypes were detected by flow cytometry, the expansion efficiency and cell function were evaluated by mix-lymphocyte reaction (MLR), IL-12 level was detected by using ELISA and the chemotactic function mediated by secondary lymphoid tissue chemokine (SLC) was determined with Transwell plate. The results indicated that after 10 days of expansion, there were no significant difference in the percentage of CD14+CD1a- cells between CB and MPB [(40.48 +/- 16.85)% vs (28.07 +/- 23.19)%, P > 0.05], but the expansion of total cells in CB was higher than that in MPB (388.88 +/- 84.63-fold vs 79.67 +/- 10.32-fold, P < 0.01), so the yield of CD14+CD1a- cells from CB was significantly higher than that from MPB too (189.42 +/- 25.02-fold vs 28.74 +/- 23.27-fold, P < 0.01). The percentage of CD83+ DCs cultured with CD40Ab/PGE2 derived from CB were higher than those cultured with TNF-alpha derived from MPB respectively [(34.52 +/- 11.22)% vs (3.70 +/- 2.27)% and (36.69 +/- 13.36)% vs (7.34 +/- 3.364)% respectively, P < 0.01]. In the same circumstance, the yield of CD83+ DCs derived from CB was much more than that from MPB (198.72 +/- 117.53 times vs 33.95 +/- 6.19 times, P < 0.01). There were no difference in stimulating capacity, IL-12 secretion and migration capacity between DCs derived from CB and MPB. It is concluded that DCs induced from CB-CD34+ cells by two-step culture possess similar functions with that from MPB-CD34+ cells, but the yield of DCs from CB CD34+ cells is much more than that from MPB CD34+ cells.

Antigens, CD34↗
PubMed2005

Comparisons of methods for linkage analysis and haplotype reconstruction using extended pedigree data.

We compare and contrast the performance of SIMPLE, a Monte Carlo based software, with that of several other methods for linkage and haplotype analyses, focusing on the simulated data from the New York City population. First, a whole-genome scan study based on the microsatellite markers was performed using GENEHUNTER. Because GENEHUNTER had to drop individuals for many of the pedigrees, we performed a follow-up study focusing on several regions of interest using SIMPLE, which can handle all pedigrees in their entirety. Second, 3 haplotyping programs, including that in SIMPLE, were used to reconstruct haplotypic configurations in pedigrees. SIMPLE emerges clearly as a preferred tool, as it can handle large pedigrees and produces haplotypic configurations without double recombinant haplotypes. For this study, we had knowledge of the simulating models at the time we performed the analysis.

Chromosome Mapping↗
PubMed2005

Palmitoyl-protein thioesterase-1 deficiency mediates the activation of the unfolded protein response and neuronal apoptosis in INCL.

Numerous proteins undergo modification by palmitic acid (S-acylation) for their biological functions including signal transduction, vesicular transport and maintenance of cellular architecture. Although palmitoylation is an essential modification, these proteins must also undergo depalmitoylation for their degradation by lysosomal proteases. Palmitoyl-protein thioesterase-1 (PPT1), a lysosomal enzyme, cleaves thioester linkages in S-acylated proteins and removes palmitate residues facilitating the degradation of these proteins. Thus, inactivating mutations in the PPT1 gene cause infantile neuronal ceroid lipofuscinosis (INCL), a devastating neurodegenerative storage disorder of childhood. Although rapidly progressing brain atrophy is the most dramatic pathological manifestation of INCL, the molecular mechanism(s) remains unclear. Using PPT1-knockout (PPT1-KO) mice that mimic human INCL, we report here that the endoplasmic reticulum (ER) in the brain cells of these mice is structurally abnormal. Further, we demonstrate that the level of growth-associated protein-43 (GAP-43), a palmitoylated neuronal protein, is elevated in the brains of PPT1-KO mice. Moreover, forced expression of GAP-43 in PPT1-deficient cells results in the abnormal accumulation of this protein in the ER. Consistent with these results, we found evidence for the activation of unfolded protein response (UPR) marked by elevated levels of phosphorylated translation initiation factor, eIF2alpha, increased expression of chaperone proteins such as glucose-regulated protein-78 and activation of caspase-12, a cysteine proteinase in the ER, mediating caspase-3 activation and apoptosis. Our results, for the first time, link PPT1 deficiency with the activation of UPR, apoptosis and neurodegeneration in INCL and identify potential targets for therapeutic intervention in this uniformly fatal disease.

Animals↗
PubMed2005

[Anatomical study about the posterior coaxial portals via posterior tibial tendon sheath for ankle arthroscopy].

OBJECTIVE: To conduct the anatomical study about the posterior coaxial portals via posterior tibial tendon (PTT) sheath for ankle arthroscopy. METHODS: Coaxial portals were established in 20 ankles by K-wires which were left in place for distance measurement between them and the posterior nerves, tendons and vessels. Ankle arthroscopy was performed in 5 fresh ankles using 2.7 mm 300 arthroscopy with the same portals as mentioned above. The maximum visible scope were recorded and the distance between the arthroscopy and the posterior nerves, tendons and vessels was also measured. RESULTS: The medial portal was located 5 - 12 mm (average, 8 mm) above the tip of medial malleolus, and the lateral portal was located 8 - 24 mm (average, 15 mm) above the tip of lateral malleolus. The coaxial portals, which traversed the PTT sheath and passed posterior to the fibular, not only separated the arthroscopy and instrument from the posterior nerves, tendons and vessels by posterior capsule but also enlarged their distance. The medial and lateral malleolus articular gap, the posterior capsule could be viewed by these portals with as much as 1/2 - 2/3 posterior articular surface of talus. Not only the tibiotalar articular gap but also the dynamic movement between the mortise and the talus were clearly observed. Arthroscopic operation could be performed by instrument through the posterolateral portal. CONCLUSIONS: The posterior coaxial portals via PTT sheath for ankle arthroscopy have such advantages as easy maneuverability, superior safety, clear vision and larger operation field under arthroscopy.

Ankle Joint↗
PubMed2005

AhR-active compounds in sediments of the Haihe and Dagu Rivers, China.

Total concentrations of compounds that can cause activation of the aryl hydrocarbon receptor (AhR) in extracts of river sediments from various locations in the Haihe and Dagu Rivers, Tianjin, China were determined by use of the in vitro H4IIE-luc cell line. AhR-active compounds were isolated from sediments by Soxhlet extraction, and the crude extracts were fractionated using a Florisil column into three Fractions. The response of samples was compared to the TCDD standard and expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TCDD-EQs). Significant dioxin-like activity was observed in each sample. The TCDD-EQs in crude extracts of sediments (SCEs), as determined with the bioassay were 2-4 times greater than the sum of the TCDD-EQs of the eluent from fractions separated with a Florisil column. The results also showed that Fractions 2 and 3 contained most of the AhR-mediated activity. The results obtained by using the bioassay were compared with those of previous measurements of the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and the structurally-similar AhR-active polychlorinated biphenyls (PCBs). It was determined that sediments from the Dagu River contained greater concentrations of TCDD-EQ than did sediments from the Haihe River except at Jingangqiao (location R3), which is associated with industrial activities in the adjacent densely populated area. The concentrations of TCDD-EQs, based on the EC20 and the relative potency ranges, of SCEs ranged from 330 to 930 and 1200 to 13,900 pg TCDD-EQ g(-1) dry wt in Haihe and Dagu Rivers, respectively.

Animals↗
PubMed2005

Effects of di-(2-ethylhexyl)-phthalate and its metabolites on the lipid profiling in rat HRP-1 trophoblast cells.

The highly directional maternal-to-fetal transfer of essential fatty acids (EFAs) across the placenta plays a critical role in guiding proper fetal development. Exposure to xenobiotics that may alter the fetal supply of EFAs/lipids could lead to fetal toxicity. Since the placenta is the first fetal arising organ that regulates fetal fatty acid homeostasis, the fatty acid/lipid composition in the placenta may serve as an indicator of fetal composition. In this study, we investigated the effects of the peroxisome proliferator chemical di-(2-ethylhexyl)-phthalate (DEHP), a widely used plasticizer and ubiquitous environmental contaminant, and its selective metabolites, mono-(2-ethylhexyl)-phthalate (MEHP) and 2-ethylhexanoic acid (EHA) on the lipid metabolome in a rat HRP-1 trophoblast model. The concentrations of ten lipid classes (cholesterol esters, diacylglycerol, triacylglycerides, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, lysophosphatidylcholine, cardiolipin, and sphingomyelin) were determined, as well as the individual fatty acid compositions, especially the omega-3 and omega-6 family of EFAs. The level of each lipid class was significantly increased upon exposure to the agents, with MEHP and EHA generally showing higher increases than DEHP. The same trends were observed in comparing the fatty acid compositions. For example, the omega-3/omega-6 fatty acids ratio did not change, although the levels of omega-3 and omega-6 fatty acids were significantly elevated upon exposure. These results suggest that DEHP and its metabolites can alter lipid metabolome in a rat placental cell line, implying that these compounds may contribute to aberrant placental EFA/lipid homeostasis caused by peroxisome proliferation, and potentially result in abnormal fetal development.

Animals↗
PubMed2005

Effects of PCBs and MeSO2-PCBs on adrenocortical steroidogenesis in H295R human adrenocortical carcinoma cells.

Some endocrine disrupting chemicals (EDCs) in the environment have been shown to exert their biological effects through interference with steroidogenesis. In this study, the potential effects of four selected polychlorinated biphenyl (PCB) congeners (PCB101, PCB110, PCB126 and PCB149) as well as several of their environmentally-relevant methylsulfonyl-(MeSO(2)-) PCB metabolites (3'-MeSO(2)-CB101, 4'-MeSO(2)-CB101, 4'-MeSO(2)-CB110, 3'-MeSO(2)-CB149 and 4'-MeSO(2)-CB149) on adrenocortical steroidogenesis were evaluated by in vitro bioassay based on the human adrenocortical carcinoma H295R cell line. The PCBs included in the study represented different structures and potential mechanisms of action. Cells were exposed for 48 h to 10 microM of each PCB congener in the presence or absence of 20% (w/w) of their corresponding MeSO(2)-PCB metabolite(s). After the chemical treatments, changes in mRNA expression of 11 steroidogenic genes (CYP11A, CYP11B1, CYP11B2, CYP17, CYP19, CYP21, 3beta-HSD1, 3beta-HSD2, 17beta-HSD1, StAR and HMGR) were quantified using molecular beacon-based real-time RT-PCR. Genes coding for enzymes involved in the later or final steps of steroid production (CYP11B1, CYP11B2, CYP19, 3beta-HSD1, 3beta-HSD2 and 17beta-HSD1) were up-regulated to various extents by most PCBs. The greatest transcriptional activations (2.8-29.9-fold) were elicited by PCB110 on CYP11B1, CYP11B2, 3beta-HSD2 and CYP19, and PCB149 on CYP11B1, 3beta-HSD1 and 17beta-HSD1. Increased expression of these steroidogenic genes might ultimately lead to a change in hormonal balance through excessive production of steroid hormones including aldosterone, cortisol and estradiol. In addition, co-treatment with 3'- and 4'-MeSO(2)-PCB149 resulted in a significant decrease in PCB149-induced 3beta-HSD1 and 17beta-HSD1 expression. This result indicates that some PCB congeners and their MeSO(2)-metabolites may affect steroidogenesis via different mechanisms. Overall, these findings suggest that PCBs and PCB metabolites can affect regulation of adrenocortical steroidogenesis.

Adrenocortical Carcinoma↗
PubMed2005

An assessment of the risks associated with polychlorinated biphenyls found in the stomach contents of stranded Indo-Pacific Humpback Dolphins (Sousa chinensis) and Finless Porpoises (Neophocaena phocaenoides) from Hong Kong waters.

The risks to Indo-Pacific Humpback Dolphins and Finless Porpoises associated with polychlorinated biphenyls (PCBs) were assessed. Stomach contents from twelve stranded Humpback Dolphins and sixteen stranded Finless Porpoises were collected. Concentrations of total and isomer-specific PCBs in the stomach contents were determined using dual-column gas chromatography equipped with electron capture detectors (GC-ECD). Risks due to the PCBs were assessed in three scenarios, based on total PCBs (summation of 41 PCB congeners), total toxicity equivalency (TEQs) and PCB 118, using the toxicity reference values (TRVs) as the threshold effects benchmarks. The calculated risk quotients (RQs) showed that risks due to PCBs were generally low or negligible. Specifically, RQs from total TEQs and total PCBs for Finless Porpoises are below one, suggesting that PCBs should be a low risk for the Finless Porpoise in Hong Kong waters. However, the Humpback Dolphin has RQs larger than 1 for total TEQs and total PCBs when the 95th percentile data were used in the evaluation. This indicates that further investigation may be needed to examine more closely the potential impact of toxic contaminants in the habitat of the Humpback Dolphin.

Animals↗
PubMed2005

Development and validation of an HPLC-UV method for the analysis of methoxyamine using 4-(diethylamino)benzaldehyde as a derivatizing agent.

Methoxyamine (MX) is a potential new anti-cancer drug. In this paper, a quantitative HPLC-UV method for MX using 4-(diethylamino)benzaldehyde (DEAB) as a derivatizing agent has been developed and validated. The studies showed that MX reacts with DEAB under acidic conditions to form protonated 4-(diethylamino)benzaldehyde o-methyloxime (DBMOH+). The equilibrium between DBMOH+ and its conjugate base 4-(diethylamino)benzaldehyde o-methyloxime (DBMO) is affected by both buffer concentration and organic solvent content in the solution. The method developed uses a reversed phase C18 column for the separation of MX derivatives, an internal standard benzil for method calibration, and a UV detector at a wavelength of 310 nm for analyte detection. The MX derivatives can be resolved in ca. 20 min. The method has a linear calibration range from 0.100 to 10.0 microM with a correlation coefficient of 0.999 for MX and a detection limit of 5 pmol with a 50 microl sample size. The intra-assay and inter-assay precision expressed in terms of percent relative standard deviation were < or =5 and 8%; and the intra-assay and inter-assay accuracy defined as the measured value divided by the accepted value multiplied by 100% were 94.2-100 and 92.6-111%, respectively. This method may be used for the analysis of MX in pharmaceutical preparations.

Acetic Acid↗