Biomedical subjects

Yu Zhang

Publications and source records attributed to Yu Zhang.

At least 91 records · Page 5Linked to original sources

PubMed2006

In vitro labeling and MRI of mesenchymal stem cells from human umbilical cord blood.

OBJECTIVE: The aim of this study was to label human umbilical cord blood mesenchymal stem cells (MSCs) with poly-l-lysine (PLL)-conjugated superparamagnetic iron oxide particles and to obtain magnetic resonance (MR) images of the labeled MSCs' suspension at 1.5 T. MATERIAL AND METHODS: PLL was conjugated with iron oxide to form superparamagnetic particles called Fe(2)O(3)-PLL. Human umbilical cord blood MSCs were isolated, purified, expanded and incubated with Fe(2)O(3)-PLL. Prussian blue stain was performed to show intracellular iron; spectrometry was used to quantify iron uptake within cells. Tetrazolium salt (MTT) assay was applied to evaluate toxicity and proliferation of MSCs labeled with various concentrations of Fe(2)O(3)-PLL. The cell apoptosis rate was determined by annexin V/propichium iodide (PI) double staining method. Vials containing cells underwent MR imaging (MRI) with T(1), T(2) and T(2)* weighted MRI. RESULTS: Iron-containing intracytoplasmatic vesicles could be observed clearly with Prussian blue staining in all samples except the unlabeled control. The iron content per cell determined by spectrometry was 64.51+/-10.32 pg. Among MSCs with and without labeling of various concentrations of Fe(2)O(3)-PLL, MTT values of light absorption had no statistically significant difference (Kruskal-Wallis test, chi(2)=10.35, P=.17). A concentration at 20 mug/ml of iron appeared most suitable for incubating cells. Of labeled and unlabeled MSCs, the early [annexin V-fluorescein isothiocyanate (FITC)-positive/PI-negative] and late (annexin V-FITC-positive/PI-positive) apoptotic cells were 10.34+/-0.43%/11.36+/-1.30% and 4.01+/-1.76%/2.98+/-1.37%, respectively, and there were no significant differences between them (P>.05). T(2) weighted image (WI) and T(2)*WI demonstrated significant decrease of signal intensity (SI) in vials containing 1 x 10(6) (1 day), 1x10(6) (8 days) and 5 x 10(5) labeled cells, in comparison with unlabeled cells (P<.05). The percentage change of SI (DeltaSI) was significantly higher in 10(6) labeled cells after 1-day culture than that in the same number of labeled cells after 8-day culture and that in 5 x 10(5) labeled cells, particularly on T(2)*WI (P<.05). Among pulse sequences, T(2)*WI demonstrated the highest DeltaSI (P<.05). CONCLUSION: The human umbilical cord blood MSCs can be labeled with Fe(2)O(3)-PLL without significant change in viability and apoptosis. The suspension of labeled MSCs can be imaged with standard 1.5-T MR equipment.

Cell Survival↗

PubMed2006

Synthesis and preliminary biological evaluation of the 99mTc labeled nitrobenzoimidazole and nitrotriazole as tumor hypoxia markers.

1-(3-1,2,4-Nitrotriazole-1-yl)-propanhydroxyiminoamide and 1-(6-nitrobenzoimidazole-1-yl)-propanhydroxyiminoamide were synthesized and radiolabeled with (99m)Tc. The (99m)Tc labeled complexes continuously accumulated in hypoxic murine sarcoma S180 cells in vitro but not in aerobic cells. Biodistribution results in mice bearing S180 tumor indicated that the tracers could localize in tumor and eliminate from it slowly. These results suggested that the (99m)Tc labeled nitrobenzoimidazole and nitrotriazole might be the novel tumor hypoxia markers.

Amides↗

PubMed2006

Diversity of centromeric repeats in two closely related wild rice species, Oryza officinalis and Oryza rhizomatis.

Oryza officinalis (CC, 2n = 24) and Oryza rhizomatis (CC, 2n = 24) belong to the Oryza genus, which contains more than 20 identified wild rice species. Although much has been known about the molecular composition and organization of centromeres in Oryza sativa, relatively little is known of its wild relatives. In the present study, we isolated and characterized a 126-bp centromeric satellite (CentO-C) from three bacterial artificial chromosomes of O. officinalis. In addition to CentO-C, low abundance of CentO satellites is also present in O. officinalis. In order to determine the chromosomal locations and distributions of CentO-C (126-bp), CentO (155 bp) and TrsC (366 bp) satellite within O. officinalis, fluorescence in situ hybridization examination was done on pachytene or metaphase I chromosomes. We found that only ten centromeres (excluding centromere 7 and 2) contain CentO-C arrays in O. officinalis, while centromere 7 comprises CentO satellites, and centromere 2 is devoid of any detectable satellites. For TrsC satellites, it was detected at multiple subtelomeric regions in O. officinalis, however, in O. rhizomatis, TrsC sequences were detected both in the four centromeric regions (CEN 3, 4, 10, 11) and the multiple subtelomeric regions. Therefore, these data reveal the evolutionary diversification pattern of centromere DNA within/or between close related species, and could provide an insight into the dynamic evolutionary processes of rice centromere.

Base Sequence↗

PubMed2006

Biological properties of neural progenitor cells isolated from the hippocampus of adult cynomolgus monkeys.

BACKGROUND: The existence of neurogenesis in the hippocampus of adult nonhuman primates has been confirmed in recent years, however, the biological properties of adult neural stem cells or neural progenitor cells (NPCs) from this region remain to be extensively explored. The present work was to investigate on the expansion of NSCs/NPCs from the hippocampus of adult cynomolgus monkeys and the examination of their characteristics in vitro. METHODS: NPCs isolated from the hippocampus of adult cynomolgus monkeys were expanded in vitro in serum-free media containing growth factors, and were then allowed to differentiate by removing mitotic factors. The expansion capacity of NPCs and their differentiation potential were assayed by immunohistochemical and immunocytochemical analysis. RESULTS: During primary culture, NPCs underwent cell division, proliferation and aggregation to form neurospheres that were growing in suspension. Without mitotic stimulation, most neurospheres adhered to the culture dish and started to differentiate. Eventually, nearly 12% of the differentiated cells expressed neuron specific marker-beta III-tubulin (Tuj1) and 84% expressed astrocyte specific marker-fibrillary acidic protein (GFAP). In addition, the expression of a neural stem cell marker, nestin, was found both in NPCs and in the subgranular zone of adult monkey hippocampus, where NPCs were originally derived. CONCLUSIONS: NPCs from the hippocampus of adult cynomolgus monkeys can be expanded to some extent in vitro and are capable of differentiating into neurons and astrocytes. Further experiments to promote the in vitro proliferation capacity of NPCs will be required before adult NPCs can be used as a useful cell model for studying adult neurogenesis and cell replacement therapy using adult stem cells.

Animals↗

PubMed2006

HPtaa database-potential target genes for clinical diagnosis and immunotherapy of human carcinoma.

Tumor-associated antigens (TAAs) have been the most actively employed targets in the clinical diagnosis and treatment of human carcinoma, such as PSA in the diagnosis of prostate cancer and NY-ESO-1 in the immunotherapy of melanoma and other cancers. However, identification of TAAs has often been hampered by the complicated and laborsome laboratory procedures. In order to accelerate the process of tumor antigen discovery, and thereby improve diagnosis and treatment of human carcinoma, we have made an effort to establish a publicly available Human Potential Tumor Associated Antigen database (HPtaa) with potential TAAs identified by in silico computing (http://www.hptaa.org). Tumor specificity was chosen as the core of tumor antigen evaluation, together with other relevant clues. Various platforms of gene expression, including microarray, expressed sequence tag and SAGE data, were processed and integrated by several penalty algorithms. A total of 3518 potential TAAs have been included in the database, which is freely available to academic users. As far as we know, this database is the first one addressing human potential TAAs, and the first one integrating various kinds of expression platforms for one purpose.

Antigens, Neoplasm↗

PubMed2006

Effects of 0.4 T rotating magnetic field exposure on density, strength, calcium and metabolism of rat thigh bones.

The current study investigated the effects of 0.4 T rotary non-uniform magnetic field (RMF) exposure on bone density in ovariectomized (OVX) rats. Results showed that many bone indexes are significantly elevated after RMF exposure compared to the control OVX group and confirmed mechanistic evidence that strong magnetic field (MF) exposure could effectively increase bone density and might be used to treat osteoporosis. Synergy of daily RMF exposure (30 min a day for 30 days using an 8 Hz rotary 0.4 T MF) with calcium supplement tended to increase the indexes of thigh bone density, energy absorption, maximum load, maximum flexibility, and elastic deformation as compared to those of untreated OVX control group. Results also revealed that the indexes of alkaline phosphatase (ALP), serum phosphate, and serum calcium were higher in rats exposed to RMF with calcium than in the untreated OVX control group. Changes in bone mineral density (BMD) and bone mineral content (BMC) were observed in rats for three months including the first month RMF exposure. Bone density in rats exposed each day for 60 min increased during 1-month exposure and continued to increase during the post-exposure period. Furthermore, bone density and calcium content in rats exposed for 90 min daily decreased initially in the exposure month; however, ratio of increase was well above the control values by the end of the post-exposure period suggesting possible window and delayed effects. The study indicated that RMF exposure to both male and OVX female rats for 120 min a day over 15 day period should effectively promote increase of bone calcium contents (BCC) and bone-specific alkaline phosphatase (BAP) in rats thigh bone as well as a corresponding decrease in deoxypyridinoline crosslinks (DPD).

Alkaline Phosphatase↗

PubMed2006

Sp5l is a mediator of Fgf signals in anteroposterior patterning of the neuroectoderm in zebrafish embryo.

The neuroectoderm is patterned along the anterior-posterior axis in vertebrate embryos. Fgf signals are required to induce the posterior neuroectodermal fates, but they repress the anterior fate. Sp5l/Spr2, an Sp1-like transcription factor family member, has been shown to be required for development of mesoderm and posterior neuroectoderm. We demonstrate here that repression of the anterior neuroectodermal markers fez and otx1 by fgf17b or fgf3 coincides with induction of sp5l in the anterior neuroectoderm, and that this repression is efficiently rescued by simultaneous sp5l knockdown. On the other hand, sp5l knockdown is able to inhibit inductive activity of ectopic Fgf signals on the expression of the posterior neuroectodermal markers gbx2, hoxb1b, and krox20. Furthermore, effect of overexpression of a dominant negative Fgf receptor on anteroposterior patterning of the neuroectoderm is rescued by sp5l overexpression. Taken together, these data suggest that sp5l mediates the functions of Fgf signals in anteroposterior patterning of the neuroectoderm during zebrafish embryogenesis.

Animals↗

PubMed2006

Studying protein-drug interaction by microfluidic chip affinity capillary electrophoresis with indirect laser-induced fluorescence detection.

We developed a microfluidic chip-affinity CE method based on indirect LIF detection to study protein-drug interactions. The interaction between heparin and BSA was quantitatively studied, as a model system. In our method, sodium fluorescein was chosen as background, and redistilled water as marker to monitor EOF. The electrophoretic mobility changes of BSA were measured, with various concentrations of heparin added to the running buffer. Each run was completed within 80 s. The binding constant was determined to be (1.24 +/- 0.05) x 10(3) M(-1), which was in good agreement with that reported in the literature.

Electrophoresis, Microchip↗

PubMed2006

Studying drug-plasma protein interactions by two-injector microchip electrophoresis frontal analysis.

We developed a simple, rapid, and sensitive two-injector microchip electrophoresis frontal analysis (MCE-FA) method for studying drug-plasma protein interactions. In this method, large volumes of a reference sample and drug-plasma protein mixture were simultaneously introduced into the respective sections of the microchannel through the separated injectors and then electrophoresed. Since the reference sample did not meet with the interacting species during migration, it could be used as an external standard. The interaction between heparin and HSA was quantitatively characterized as a model system. The binding constant was found to be (1.53 +/- 0.01) x 10(4) M(-1).

Anticoagulants↗

PubMed2006

Identification of metastasis candidate proteins among HCC cell lines by comparative proteome and biological function analysis of S100A4 in metastasis in vitro.

Widespread metastasis of hepatocellular carcinoma (HCC) was a complex cascade of events, which is still beyond full appreciation. Screening key proteins, which play a critical role in metastasis, using high-throughput proteomics approach help discover valuable biomarkers and elucidate the mechanism of metastasis. This study was to find out some metastasis candidate proteins among HCC cell lines with various metastatic potential by comparative proteomics, and then further validate the biological function of these proteins in metastasis in vitro. The protein profiles of metastatic HCC cell lines (MHCC97H and MHCC97L) displayed obvious differences compared with nonmetastatic ones (Hep3B). Twenty-six metastasis candidate proteins, which were identified by on-line LC-ESI-MS/MS, such as S100 calcium-binding protein A4 (S100A4), annexin 1, etc., might have much application in diagnostic procedures and prognosis evaluation. S100A4, as a leading different metastasis candidate protein, which overexpressed only in the metastatic cells, was selected for further investigation. A series of assays related to invasion and metastasis in vitro, including cell motility, invasion, and matrix metalloproteinases (MMPs) secretion, were performed in MHCC97H/antisense recombinant plasmid to S100A4 (pcDNA3.1(+) AS S100A4) and the mock controls. All the data in the present study suggested that S100A4 might contribute to HCC invasion and metastasis through two paths of matrix metalloproteinase (MMP9) secretion regulation and strengthened motility and invasion properties.

Apoptosis↗

PubMed2006

Identification and analysis of altered alpha1,6-fucosylated glycoproteins associated with hepatocellular carcinoma metastasis.

Tumor metastasis might be associated with the expression levels of cellular glycoproteins and the alteration of their glycan parts. In order to screen the aberrantly alpha1,6-fucosylated glycoproteins related to hepatocellular carcinoma (HCC) metastasis, a high-throughput glycomic approach which consisted of 2-DE, electronic transfer of proteins, lectin affinity blot and precipitation, and MALDI-TOF-MS/MS, was established. Lens culinaris agglutinin (LCA) affinity glycoprotein profiles of higher and lower metastatic HCC cell lines were compared and analyzed. Seven out of 34 identified glycoproteins were differentially displayed; they were cytokeratin 8 (CK8), annexin I, annexin II, heterogeneous nuclear ribonucleoprotein A/B, PDZ and LIM domain 1, RNA-binding motif protein 4, and poly(rC)-binding protein 1. On comparison with Hep3B, CK8 showed a higher affinity to Ricinus communis agglutinin 1 (RCA-I) and LCA, and annexin I presented a higher affinity to LCA and Con A by the lectin-binding assay. Furthermore, the up-regulation of CK8, annexin I, and annexin II were found by Western blot and immunofluorescence analysis in higher metastatic HCC cell lines. This implied that the alteration of CK8, annexin I, and annexin II both in their expression levels and their glycan parts might be related to metastatic ability, and play a critical role in the process of HCC metastasis.

Annexin A1↗

PubMed2006

Anti-fatigue activity of a triterpenoid-rich extract from Chinese bamboo shavings (Caulis bamfusae in taeniam).

The anti-fatigue activity of a pentacyclic triterpenoid extract from bamboo shavings (EBS) from the bark of bamboo (Bambusa tuldoides Munro), was evaluated in BALB/c mice. EBS, isolated by the supercritical CO(2) fluid extraction (SFE) technique, was given to mice at concentrations of 0.04 (low-dose group), 0.08 (middle-dose group) and 0.25 g/kg body weight (high-dose group). The anti-fatigue activity of EBS was estimated by the change in body weight, weight-loaded swimming test and climbing test, and corresponding parameters including serum urea nitrogen, hepatic glycogen and blood lactic acid were measured. The results showed that an appropriate level of EBS could prolong the weight-loaded swimming and climbing time, and had an active effect on the serum urea nitrogen, hepatic glycogen and blood lactic acid level in BALB/c mice, which significantly embodied the anti-fatigue activity of EBS. Overall, it is predicted that EBS, being a composition mainly containing a group of pentacyclic triterpenoids, and its main triterpenoid components have great potential for application in relevant fields for its anti-fatigue activity.

Animals↗

PubMed2006

Iminodiacetic acid derivatized porous silicon as a matrix support for sample pretreatment and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis.

Iminodiacetic acid (IDA)-1,2-epoxy-9-decene has been synthesized and covalently linked to the surface of porous silicon wafer through a photochemical reaction. The negatively charged carboxylic acid groups on the porous silicon wafer are capable of binding oppositely charged species from sample solutions through electrostatic interactions. This allows the removal of contaminants prior to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) by simply washing the porous silicon surface. The carboxylic acid end groups on porous silicon can be used to selectively bind and concentrate target species in sample solutions. Furthermore, Fe(3+)-IDA-derivatized porous silicon was prepared to specifically and effectively concentrate phosphopeptides from the tryptic digests of phosphoproteins, followed by MALDI-MS analysis.

Caseins↗

PubMed2006

Application of PCR-DGGE to analyse the yeast population dynamics in slurry reactors during degradation of polycyclic aromatic hydrocarbons in weathered oil.

Slurry-phase reactors have been used to investigate the biodegradation feasibility of polycyclic aromatic hydrocarbons (PAHs) in weathered crude oil, by mixed culture containing five PAHs-degrading yeast strains. Yeasts were isolated from the oily soil by enrichment culture, using phenanthrene as a sole carbon source, and identified based on the 26S ribosomal DNA (rDNA) sequence. Yeast strains belonged to the genera Candida, Pichia, Rhodotorula and Sporidiobolus. The experiment was carried out for a period of 6 weeks at room temperature with a solid : liquid ratio of 50% w/w. The results showed that high removal efficiency was obtained for all PAHs, including low molecular weight (LMW) and high molecular weight (HMW) compounds (89.3-98.6% and 66.3-89.4% within 6 weeks, respectively). The higher removal efficiency for HMW-PAHs obtained in this work suggested that yeast strains mixture could play an important role to reclaim oil-contaminated sites. Denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR)-amplified 26S rRNA genes was used to follow the changes of yeast populations during the slurry reactor process. The results of DGGE indicated that Candida maltosa-like and Pichia guilliermondii were the dominant species but Rhodotorula dairenensis appeared as a weak band and Sporidiobolus salmonicolor and Pichia anomala disappeared during the study. Moreover, the results showed that all of the five strains, including the two belonging to the same genus, could be differentiated from each other in the DGGE profile.

Base Sequence↗

PubMed2006

Molecular characterization of a bacterial consortium enriched from an oilfield that degrades phenanthrene.

Characterization of functional and phylogenetic genes was carried out on a bacterial consortium, enriched from a water treatment system of an oilfield, that could use phenanthrene as the sole carbon source. The mixed culture degraded 130 mg phenanthrene l(-1) in 16 days, which is significantly faster than previously reported pure cultures. The existence of catabolic genes (nahAc, C23O) in the mixed culture was quantitated by most probable number PCR. The plasmid encoding phenanthrene catabolic genes increased relative to the chromosome genes. Heterogeneous bacteria were present according to both PCR denaturing gradient gel electrophoresis and cloning methods, suggesting the possible existence of cooperation between different biochemical PAH-transforming pathways.

Bacteria↗

PubMed2006

In-situ hardening hydroxyapatite-based scaffold for bone repair.

Musculoskeletal conditions are becoming a major health concern because of an aging population and sports- and traffic-related injuries. While sintered hydroxyapatite implants require machining, calcium phosphate cement (CPC) bone repair material is moldable, self-hardens in situ, and has excellent osteoconductivity. In the present work, new approaches for developing strong and macroporous scaffolds of CPC were tested. Relationships were determined between scaffold porosity and strength, elastic modulus and fracture toughness. A biocompatible and biodegradable polymer (chitosan) and a water-soluble porogen (mannitol) were incorporated into CPC: Chitosan to make the material stronger, fast-setting and anti-washout; and mannitol to create macropores. Flexural strength, elastic modulus, and fracture toughness were measured as functions of mannitol mass fraction in CPC from 0% to 75%. After mannitol dissolution in a physiological solution, macropores were formed in CPC in the shapes of the original entrapped mannitol crystals, with diameters of 50 microm to 200 microm for cell infiltration and bone ingrowth. The resulting porosity in CPC ranged from 34.4% to 83.3% volume fraction. At 70.2% porosity, the hydroxyapatite scaffold possessed flexural strength (mean +/- sd; n = 6) of (2.5 +/- 0.2) MPa and elastic modulus of (0.71 +/- 0.10) GPa. These values were within the range for sintered porous hydroxyapatite and cancellous bone. Predictive equations were established by regression power-law fitting to the measured data (R(2) > 0.98) that described the relationships between scaffold porosity and strength, elastic modulus and fracture toughness. In conclusion, a new graft composition was developed that could be delivered during surgery in the form of a paste to harden in situ in the bone site to form macroporous hydroxyapatite. Compared to conventional CPC without macropores, the increased macroporosity of the new apatite scaffold may help facilitate implant fixation and tissue ingrowth.

Aging↗

PubMed2006

Parameter estimation of an asymmetric vocal-fold system from glottal area time series using chaos synchronization.

In this paper, we apply an iterative parameter adaption scheme based on chaos synchronization to estimate system parameters of the asymmetric vocal folds from glottal area time series. The original asymmetric vocal-fold system associated with recurrent laryngeal paralysis shows chaotic vibrations with positive Lyapunov exponents. Aperiodic glottal area time series from the original system will be applied as the feedback variable coupling the simulative and the original vocal-fold systems. The parameter adaption technique based on chaos synchronization is employed to manipulate the simulative system parameters. The chaotic vibrations, system parameters, and the bifurcation diagram of the original vocal-fold system can be exactly reproduced in the simulative system, and the two chaotic systems can be synchronized. Furthermore, the effects of noise, sampling rate, and equation difference due to nonlinear spring terms on vocal-fold parameter estimations are investigated. Despite large noise perturbations, large equation differences, and low sampling rate, the parameter adaption scheme can effectively estimate the original vocal-fold system parameters. This study provides a theoretical base to apply chaos synchronization to estimate the vocal-fold system parameters from the glottal area data and show its potential application in laryngeal physiology.

Algorithms↗

PubMed2006

Theoretical and experimental studies of parameter estimation based on chaos feedback synchronization.

In this paper, we perform theoretical and experimental studies of parameter estimation based on chaos feedback synchronization. The Chua chaotic system is applied as the original system, and its time series of a single variable is applied as a feedback variable to drive a simulative system. The simplex method is employed to minimize the synchronization error in the simulative system to iteratively approach the original system parameters. Furthermore, the effects of feedback function, feedback weight, and noise are investigated. The parameter estimation method based on feedback synchronization shows its robustness to noise perturbation. Finally, the circuit experiment of parameter estimation is implemented in order to examine its practical applicability. The original Chua circuit parameters can be well approached from its recorded time series of a single variable. The results show the parameter estimation method based on feedback synchronization may be capable of estimating real system parameters from a chaotic time series.

Algorithms↗