Biomedical subjects

Hua Wu

Publications and source records attributed to Hua Wu.

At least 37 records · Page 2Linked to original sources

PubMed2005

Further insights into the universality of colloidal aggregation.

Dynamic light scattering (DLS) performed at various scattering wave vectors provides detailed information about the aggregation kinetics and the cluster mass distribution (CMD) in colloidal dispersions. Detailed modeling of the aggregation kinetics with population balance equations requires a quantitative connection between the CMD and measurable quantities such as the angle dependent hydrodynamic radii obtained by DLS. For this purpose we evaluate and compare various models for the structure factor of fractal aggregates. Additionally, we introduce a simple scattering model that accounts for the contribution of internal cluster dynamics of fractal clusters to the first cumulant of the dynamic structure factor. We show that this contribution allows to quantitatively describe previously measured experimental data on the scattering wave vector dependence of the hydrodynamic radius in diffusion limited cluster-cluster aggregation (DLCA), which was shown to exhibit some kind of universality behavior (master curve). Using the same scattering model, we analyze a similar set of experimental data but in reaction limited cluster-cluster aggregation (RLCA). We find that in this case the crossover from RLCA to DLCA and gravitational settling both have a significant influence on the CMD and consequently on the scattering wave vector dependent DLS data. Only when accounting for both these effects they temporarily compensate each other and a satisfactory representation of the aggregation master curve is possible for the RLCA data at longer times. Indeed, we find that either crossover from RLCA to DLCA or gravitational settling, when present individually, causes the loss of a master curve for aggregation.

Biophysics↗

PubMed2005

Effect of electromagnetic fields on proliferation and differentiation of cultured mouse bone marrow mesenchymal stem cells.

In order to study the effects of electromagnetic fields (EMFs) on proliferation, differentiation and intercellular cyclic AMP (cAMP) in mouse bone marrow mesenchymal stem cells (MSCs) in vitro, the mouse bone MSCs were isolated and cultured in vitro. The third passage MSCs were divided into 4 groups and stimulated with EMFs. The cellular proliferation (MTT), the cellular differentiation (alkaline phosphatase activity, ALP), and the intercellular cAMP level were investigated at different time points. The results showed that EMF (50Hz pulse burst 2 mT peak) inhibited the cellular proliferation (P < 0.05), enhanced the cellular differentiation (P < 0. 05), and increased the intercellular cAMP level (P < 0.01) in the early time of the stimulation (1-3 days), but the intercellular cAMP level did not increased further in the later days. We are led to conclude that the cAMP may be involved in the mediation of the growth inhibitory and differentiation-inducing signals of specific EMFs in vitro.

Alkaline Phosphatase↗

PubMed2005

Porous-conductive chitosan scaffolds for tissue engineering II. in vitro and in vivo degradation.

Porous-conductive chitosan scaffolds were fabricated by blending conductive polypyrrole (PPy) particles with chitosan solution and employing an improved phase separation method. In vitro and in vivo degradation behaviors of these scaffolds were investigated. In the case of in vitro degradation, an enzymatic degradation system was employed and lysozyme was used as a working enzyme. Meanwhile, the degradation products of scaffolds, glucosamine and N-acetyl-glucosamine, were also analyzed with a HPLC method. In vivo degradation of scaffolds was performed by subcutaneously implanting these scaffolds in rat for pre-scheduled time intervals. In the both cases, the weight-loss of scaffolds was monitored during the whole degradation process for evaluating the degradation of scaffolds. The changes in conductivity of scaffolds afterin vitro or in vivo degradation were also measured using a four-point technique. It was observed that the pore parameters of scaffolds themselves could significantly influence the degradation behaviors of scaffolds but the PPy content in the scaffolds seemed not to impart its effect to the degradation of scaffolds. Degradation dynamics of scaffolds and conductivity measurements indicated that these scaffolds shown fairly different behaviors in their in vitro and in vivo degradation process. According to the results obtained from in vitro and in vivo degradation of scaffolds and based on some requirements of practical tissue engineering application, it was suggested that the PPy content in the scaffold should be slightly higher than 3 wt.% but lower than 6 wt.%.

Animals↗

PubMed2005

[Changes in pulmonary function in severe acute respiratory syndrome patients during convalescent period].

OBJECTIVE: To investigate the changes and pattern of pulmonary function in severe acute respiratory syndrome (SARS) patients during convalescent period. METHODS: Pulmonary function tests were performed in 26 SARS convalescent patients regularly every 3 months after their discharge from hospital. The significance of changes in pulmonary function indexes was analyzed. RESULTS: Restrictive pulmonary ventilation function and diffusing dysfunction of the lung were found in one third of the patients during third to sixth month from onset. There was a little improvement in forced vital capacity (FVC), one second forced expiratory volume (FEV(1.0)), functional residual capacity (FRC) and residual volume (RV) as convalescent period was prolonged, but no difference was found between different stages (3-6 months, 6-9 months, 9-12 months, 12-15 months and 15-17 months). Meanwhile, the FEV(1.0)/FVC showed no significant change. However, there was an obvious improvement in total lung capacity (TLC) and diffusing capacity of the lung for carbon monoxide (DLCO) with the elapse of time, and also a significant difference was found between the later stage and the earlier stage. CONCLUSION: Pulmonary dysfunction is found among some SARS patients after convalescence presenting mainly as restrictive ventilatory function and diffusing capacity abnormality. These dysfunctions would improve gradually with the elapse of time.

Adult↗

PubMed2005

[Preliminary research on the proliferation and differentiation of rat bone marrow mesenchymal stem cells with exposure to 50 Hz magnetic fields].

A preliminary experimental research on the proliferation and differentiation of rat bone marrow mesenchymal stem cells with exposure to 50 Hz magnetic fields is done. The experimental results can be well repeated, showing that 50 Hz magnetic fields can evidently affect the proliferation and differentiation of rat bone marrow mesenchymal stem cells (MSCs), besides, the results are not linear with the amplitude of magnetic fields, but existing therein a 'window' phenomenon. At the end of this paper, the domestic and overseas development of the research is discussed on with the emphasis how to cure the bone fracture with the help of magnetic fields, and our investigative thoughts are also presented.

Animals↗

PubMed2005

[Efficacy of concurrent radio-chemotherapy and chemotherapy alone in the treatment of locally advanced non-small-cell lung cancer].

OBJECTIVE: To evaluate the effect and acute toxicity of concurrent radio-chemotherapy, by NVB and DDP, plus concurrent radiotherapy in comparison with chemotherapy alone in the treatment of inoperable locally advanced non-small-cell lung cancer (LANSCLC). METHODS: Sixty-four patients with inoperable LANSCLC were randomly divided by envelope method into two groups: concurrent radio-chemotherapy group (n = 33) and conventional chemotherapy group (n = 31). The patients in conventional chemotherapy group were treated by NP regimen (NVB + DDP): NVB 25 mg/m(2), d1, 8 and DDP 25-30 mg/m(2) d1-3. In the radio-chemotherapy group by NP regimen plus conventional radiotherapy by (60)Co: 64-68 Gy/2 Gy x 5/w x 6-7w. RESULTS: All patients completed the treatment schedule. The overall response rate (CR + PR) in the radio-chemotherapy group was significantly higher than that in the conventional chemotherapy group: 81.8% vs 45.2%, (P < 0.01) with 1- and 2-year survival rates of 69.7% vs 38.7% (P < 0.05) and 39.4% vs 16.1% (P < 0.05). without any significant difference in the acute toxicity between two groups (P > 0.05). CONCLUSION: Compared with conventional chemotherapy (NVP and DDP), concurrent radio-chemotherapy (NVP and DDP plus concurrent radiotherapy) is more effective and tolerable for the inoperable locally advanced non-small-cell lung cancer.

Adult↗

PubMed2005

[Characteristics of airway inflammatory cells and mediators in eosinophilic bronchitis patients].

OBJECTIVE: To investigate the features of airway inflammation in patients with eosinophilic bronchitis (EB) by analyzing the inflammatory cells and mediators in induced sputum and bronchoalveolar lavage fluid (BALF). METHODS: Sputum induced by hypertonic saline aerosol inhalation was collected in 43 patients with EB (EB group), 20 patients with cough variant asthma (CVA, CVA group), 16 patients with bronchial asthma (asthma group) and 21 healthy controls (healthy group). Bronchoalveolar lavage was also performed in 11 patients with EB and 10 patients with CVA. Differential cell count was carried out in sputum and BALF. Levels of eosinophilic cationic protein (ECP), leukotriene C(4) (LTC(4)) and histamine in sputum and BALF were measured. RESULTS: The percentage of sputum eosinophils (EOS) showed significant difference among the four groups; healthy group 0.0020 +/- 0.0050, EB group 0.1130 +/- 0.1470, CVA group 0.1900 +/- 0.1800, asthma group 0.3860 +/- 0.2670 (P < 0.01). The difference between asthma group and CVA group, and the difference between CVA group and EB group were significant (P < 0.05). The percentage of EOS in BALF was (0.011 +/- 0.016) in EB group, (0.053 +/- 0.040) in CVA group, the difference being significant (P < 0.05). The concentration of sputum ECP was (0.62 +/- 0.66) mg/L in EB group, (1.27 +/- 1.74) mg/L in CVA group, (0.07 +/- 0.10) mg/L in healthy group, the difference among the three groups being significant (P < 0.01). The difference of LTC(4) level was also significant when CVA group (0.65 +/- 0.62) microg/L was compared with EB group (0.39 +/- 0.61) microg/L (P < 0.05) and healthy group (0.15 +/- 0.11) microg/L (P < 0.01). The difference of histamine level in the supernatant of BALF was significant between CVA group (3.4 +/- 1.4) microg/L and EB group (1.6 +/- 1.5) microg/L (P < 0.05). CONCLUSIONS: EOS infiltration is mainly localized to the central airway in EB, with lower airway levels of LTC(4) and histamine as compared to CVA. These inflammatory features may partly explain the absence of non-specific airway hyperresponsiveness in patients with EB.

Adult↗

PubMed2005

[Gene mutation detection in a cleidocranial dysplasia family].

OBJECTIVE: To study gene mutation in Chinese patients with cleidocranial dysplasia. METHODS: A three generation family with the clinical diagnosis of cleidocranial dysplasia was investigated in present study. Genomic DNA was extracted from peripheral blood samples of each of the family members. Direct sequencing of the PCR products of the coding region of CBFA1 gene was used to identify the mutations. RESULTS: In each patient of the family, a heterozygous missense mutation, cDNA 674 G > A (R225Q), was detected in CBFA1 exon 3. The mutation changed the sequence in runt domain of the protein. CONCLUSIONS: Our findings indicate that mutation in CBFA1 is responsible for the tooth agenesis and other phenotypes of cleidocranial dysplasia in this Chinese family. The mutation detection could be applied in prenatal diagnosis for the family.

Adolescent↗

PubMed2005

[A survey of number and morphology anomalies in permanent teeth of 6 453 youths between 17 to 21 years old].

OBJECTIVE: To investigate the status of number and morphology anomalies in the permanent teeth. METHODS: A survey of anomalies of number and morphology in the permanent teeth was carried out in 6 453 students who were 17 to 21 years old in 3 colleges during 2002 to 2004. Chi-square test was used to analyze the sex distribution, the involved tooth types and the associated anomalies. RESULTS: The overall prevalence of dental number and morphology anomalies was 16.07%. The prevalence rates of peg-shape (conical) tooth, dens evaginatus and hypodontia were higher in females compared to males (P < 0.05). Dens evaginatus and peg-shape teeth often involved maxillary lateral incisors, Dens evaginatus often involved mandibular second premolars. Fused teeth and hypodontia often involved mandibular incisors. The prevalence of hypodontia coincident with peg-shaped teeth was higher than other associated anomalies (P < 0.01). CONCLUSIONS: The result was similar to other investigations, but peg-shape teeth and dens evaginatus were more prevalent in females than in males.

Adolescent↗

PubMed2004

Porous-conductive chitosan scaffolds for tissue engineering, 1. Preparation and characterization.

Novel porous-conductive chitosan scaffolds were fabricated by incorporating conductive polypyrrole (PPy) particles into a chitosan matrix and employing a phase separation technique to build pores inside the scaffolds. Conductive polypyrrole particles were prepared with a microemulsion method using FeCl3 as a dopant. The preparation conditions were optimized to obtain scaffolds with controlled pore size and porosity. The conductivity of the scaffolds was investigated using a standard four-point probe technique. It was found that several kinds of scaffolds showed a conductivity close to 10(-3) S.cm(-1) with a low polypyrrole loading of around 2 wt.-%. The main mechanical properties, such as tensile strength, breaking elongation and Young's modulus of the scaffolds, were examined both in the dry and in the hydrated states. The results indicated that a few different kinds of scaffolds exhibited the desired mechanical strength for some tissue engineering applications. The miscibility of polypyrrole and chitosan was also evaluated using a dynamic mechanical method. The presence of significant phase separation was detected in non-porous PPy/chitosan scaffolds but enhanced miscibility in porous PPy/chitosan scaffolds was observed.

Biocompatible Materials↗

PubMed2004

Rotational diffusivity of fractal clusters.

The rotational diffusion behavior of fractal clusters generated through an off-lattice cluster-cluster aggregation algorithm in both diffusion-limited cluster aggregation and reaction-limited cluster aggregation conditions is investigated. The extended Kirkwood-Riseman theory (Garcia de la Torre et al., Macromolecules, 1987) is used to estimate the cluster rotational diffusion tensor. The three eigenvalues of this tensor, which correspond to the three main rotational diffusivity values of the cluster, have been computed for each generated cluster. Once the eigenvalues have been sorted in ascending order, each of them has been averaged over several thousands of clusters. It is found that one of the three main average rotational diffusivities is substantially larger than the other two, indicating significant anisotropy of fractal clusters. Moreover, a rotational hydrodynamic radius Rh,r has been determined on the basis of the mean value of the three average rotational diffusivities, which is about 25% larger than the mean translational hydrodynamic radius Rh calculated through the same Kirkwood-Riseman theory. Finally, the obtained Rh,r values have been applied to interpret dynamic light scattering data from aggregating colloidal systems and to investigate the reliability of the assumption, Rh = Rh,r, typically made in the literature.

Journal Article↗

PubMed2004

First-principles study of ferromagnetism in epitaxial Si-Mn thin films on Si(001).

Density-functional theory calculations are employed to investigate both the epitaxial growth and the magnetic properties of thin Mn and MnSi films on Si(001). For single Mn adatoms, we find a preference for the second-layer interstitial site. While a monolayer Mn film is energetically unfavorable, a capping-Si layer significantly enhances the thermodynamic stability and induces a change from antiferromagnetic to ferromagnetic order. For higher Mn coverage, a sandwiched Si-Mn thin film (with CsCl-like crystal structure) is found to be the most stable epitaxial structure. We attribute the strong ferromagnetic intralayer coupling in these films to Mn 3d-Si 3s3p exchange.

Journal Article↗

PubMed2004

Experimental investigation of colloidal gel structures.

We investigate experimentally the structural properties of colloidal gels, formed under both diffusion-limited and reaction-limited aggregation conditions, using light scattering measurements and compare the results with the literature Monte Carlo (MC) simulations. The scattering structure factors have been measured for the two classes of gels in the range of the particle volume fractions between 0.02 and 0.07. From these, the corresponding fractal dimension values have been estimated. These have been found to be in good agreement with those estimated from the structure factors computed from MC simulated gels. On the basis of our previous research (Lattuada et al. Langmuir 2003, 19, 6312), this confirms that the scattering structure factor of a gel provides erroneously a small fractal dimension value, which decreases as the particle volume fraction increases. Furthermore, it is observed that the average size of the fractal clusters is larger in real gels than in simulated gels.

Journal Article↗

PubMed2004

Different look at the spin state of Co(3+) ions in a CoO(5) pyramidal coordination.

Using soft-x-ray absorption spectroscopy at the Co L(2,3) and O K edges, we demonstrate that the Co3+ ions with the CoO5 pyramidal coordination in the layered Sr2CoO3Cl compound are unambiguously in the high spin state. Our result questions the reliability of the spin state assignments made so far for the recently synthesized layered cobalt perovskites and calls for a reexamination of the modeling for the complex and fascinating properties of these new materials.

Journal Article↗

PubMed2004

pRb inactivation in mammary cells reveals common mechanisms for tumor initiation and progression in divergent epithelia.

Retinoblastoma 1 (pRb) and the related pocket proteins, retinoblastoma-like 1 (p107) and retinoblastoma-like 2 (p130) (pRb(f), collectively), play a pivotal role in regulating eukaryotic cell cycle progression, apoptosis, and terminal differentiation. While aberrations in the pRb-signaling pathway are common in human cancers, the consequence of pRb(f) loss in the mammary gland has not been directly assayed in vivo. We reported previously that inactivating these critical cell cycle regulators in divergent cell types, either brain epithelium or astrocytes, abrogates the cell cycle restriction point, leading to increased cell proliferation and apoptosis, and predisposing to cancer. Here we report that mouse mammary epithelium is similar in its requirements for pRb(f) function; Rb(f) inactivation by T(121), a fragment of SV40 T antigen that binds to and inactivates pRb(f) proteins, increases proliferation and apoptosis. Mammary adenocarcinomas form within 16 mo. Most apoptosis is regulated by p53, which has no impact on proliferation, and heterozygosity for a p53 null allele significantly shortens tumor latency. Most tumors in p53 heterozygous mice undergo loss of the wild-type p53 allele. We show that the mechanism of p53 loss of heterozygosity is not simply the consequence of Chromosome 11 aneuploidy and further that chromosomal instability subsequent to p53 loss is minimal. The mechanisms for pRb and p53 tumor suppression in the epithelia of two distinct tissues, mammary gland and brain, are indistinguishable. Further, this study has produced a highly penetrant breast cancer model based on aberrations commonly observed in the human disease.

Brain Neoplasms↗

PubMed2004

Which genetic marker for which conservation genetics issue?

Conservation genetics focuses on the effects of contemporary genetic structuring on long-term survival of a species. It helps wildlife managers protect biodiversity by identifying a series of conservation units, which include species, evolutionarily significant units (ESUs), management units (MUs), action units (AUs), and family nets (FNs). Although mitochondrial DNA (mtDNA) evolves 5-10 times faster than single-copy nuclear DNA (scnDNA), it records few traces of contemporary events. Thus, mtDNA can be used to resolve taxonomic uncertainties and ESUs. Variable number of tandem repeats (VNTRs) evolve 100-1000 times faster than scnDNA and provide a powerful tool for analyzing recent and contemporary events. VNTR analysis techniques include polymerase chain reaction (PCR)-based microsatellite assays and oligonucleotide probing. Size homoplasy problems in PCR-based microsatellite assays can strongly affect the inference of recent population history. The high homozygosity in endangered species is reflected in a relatively low number and level of variability in microsatellite loci. This combined with "allelic dropout" and "misprinting" errors contributes to the generation of highly biased genetic data following analyses of natural populations. Thus, in conservation genetics, microsatellites are of limited use for identifying ESUs, MUs, and AUs. In contrast to PCR-based microsatellite analysis, oligonucleotide probing avoids errors resulting from PCR amplification. It is particularly suitable for inferring recent population history and contemporary gene flow between fragmented subpopulations. Oligonucleotide fingerprinting generates individual-specific DNA banding patterns and thus provides a highly precise tool for monitoring demography of natural populations. Hence, DNA fingerprinting is powerful for distinguishing ESUs, MUs, AUs, and FNs. The use of oligonucleotide fingerprinting and fecal DNA is opening new areas for conservation genetics.

Animals↗

PubMed2004

Effects of vascular endothelial cell growth factor on fibrovascular ingrowth into rabbits hydroxyapatite orbital implant.

The effects of different concentrations of vascular endothelial cell growth factor (VEGF) on the fibrovascular ingrowth into rabbits hydroxyapatite orbital implant were investigated. Twelve New Zealand white rabbits were divided into 3 groups and received hydroxyapatite orbital implant surgery in their right eyes. Before and after the operation, the implants were treated with 10 ng/ml VEGF, 100 ng/ml VEGF, or normal saline as control group. The animals received technetium bones scan at 2, 4, and 6 weeks postoperatively. The mean radioactivity counts within region of interest (ROI) of the surgery eye (R) and the non-surgery eye (L) in the same animal were tested, and the R/L ratios were calculated. The implants were harvested at 6th weeks and examined histopathologically. The results showed that at second week, there was no significant difference in mean R/L ratios between VEGF group and control group (F=2.83, P=0.111); At 4th week (F=7.728, P=0.011) and 6th week (F=7.831, P=0.011) postoperatively, the mean ratios in VEGF groups were significantly higher than that in control group. At 6th week postoperatively, the fibrovascularization rates in VEGF groups were higher than in control group significantly (F=8.711, P=0.008). It was suggested that VEGF could promote the fibrovascular ingrowth into hydroxyapatite orbital implant, thus might shorten the time required for complete vascularization of the HA orbital implant.

Animals↗

PubMed2004

Use of PEI-coated magnetic iron oxide nanoparticles as gene vectors.

To evaluate the feasibility of using polyethyleneimine (PEI) coated magnetic iron.oxide nanoparticles (polyMAG-1000) as gene vectors. The surface characteristics of the nanoparticles were observed with scanning electron microscopy. The ability of the nanoparticles to combine with and protect DNA was investigated at different PH values after polyMAG-1000 and DNA were combined in different ratios. The nanoparticles were tested as gene vectors with in vitro transfection models. Under the scanning electron microscope the nanoparticles were about 100 nm in diameter. The nanoparticles could bind and condense DNA under acid, neutral and alkaline conditions, and they could transfer genes into cells and express green fluorescent proteins (GFP). The transfection efficiency was highest (51%) when the ratio of nanoparticles to DNA was 1:1 (v:w). In that ratio, the difference in transfection efficiency was marked depending on whether a magnetic field was present or not: about 10% when it was absent but 51% when it was present. The magnetic iron oxide nanoparticles coated with PEI may potentially be used as gene vectors.

Breast Neoplasms↗