Biomedical subjects

Jun Wang

Publications and source records attributed to Jun Wang.

At least 217 records · Page 12Linked to original sources

PubMed2005

Influence of ethanol-gasoline blended fuel on emission characteristics from a four-stroke motorcycle engine.

Emission characteristics from a four-stroke motorcycle engine using 10% (v/v) ethanol-gasoline blended fuel (E10) were investigated at different driving modes on the chassis dynamometers. The results indicate that CO and HC emissions in the engine exhaust are lower with the operation of E10 as compared to the use of unleaded gasoline, whereas the effect of ethanol on NO(X) emission is not significant. Furthermore, species of both unburned hydrocarbons and their ramifications were analyzed by the combination of gas chromatography/mass spectrometry (GC/MS) and gas chromatography/flame ionization detection (GC/FID). This analysis shows that aromatic compounds (benzene, toluene, xylene isomers (o-xylene, m-xylene and p-xylene), ethyltoluene isomers (o-ethyltoluene, m-ethyltoluene and p-ethyltoluene) and trimethylbenzene isomers (1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene)) and fatty group ones (ethylene, methane, acetaldehyde, ethanol, butene, pentane and hexane) are major compounds in motorcycle engine exhaust. It is found that the E10-fueled motorcycle engine produces more ethylene, acetaldehyde and ethanol emissions than unleaded gasoline engine does. The no significant reduction of aromatics is observed in the case of ethanol-gasoline blended fuel. The ethanol-gasoline blended fuel can somewhat improve emissions of the rest species.

Air Pollutants↗

PubMed2005

Biodegradable and photocrosslinkable polyphosphoester hydrogel.

A new biodegradable, photocrosslinkable and multifunctional macromer, poly(6-aminohexyl propylene phosphate) (PPE-HA)-ACRL, was synthesized by conjugation of acrylate groups to the side chains of PPE-HA. By controlling the synthetic conditions, different weight fractions of acrylate in the macromers were achieved as confirmed by 1H NMR. The hydrogels obtained from PPE-HA-ACRL through photocrosslinking were dominantly elastic. With increasing acrylate contents in the macromers, the hydrogels exhibited a lower swelling ratio and higher mechanical strength. The hydrogels with different crosslinking densities lost between 4.3% and 37.4% of their mass in 84 days when incubated in phosphate-buffered saline at 37 degrees C. No significant cytotoxicity of the macromers against bone marrow-derived mesenchymal stem cells from goat (GMSC) was observed at a concentration up to 10mg/ml. Finally, GMSCs encapsulated in the photopolymerized gel maintained their viability when cultured in osteogenic medium for three weeks. Clear mineralization in the hydrogel scaffold was revealed by Von Kossa staining. This study suggests the potential of these biodegradable and photocrosslinkable as injectable tissue engineering scaffolds.

Absorbable Implants↗

PubMed2005

Origin and evolution of new exons in rodents.

Gene number difference among organisms demonstrates that new gene origination is a fundamental biological process in evolution. Exon shuffling has been universally observed in the formation of new genes. Yet to be learned are the ways new exons originate and evolve, and how often new exons appear. To address these questions, we identified 2695 newly evolved exons in the mouse and rat by comparing the expressed sequences of 12,419 orthologous genes between human and mouse, using 743,856 pig ESTs as the outgroup. The new exon origination rate is about 2.71 x 10(-3) per gene per million years. These new exons have markedly accelerated rates both of nonsynonymous substitutions and of insertions/deletions (indels). A much higher proportion of new exons have K(a)/K(s) ratios >1 (where K(a) is the nonsynonymous substitution rate and K(s) is the synonymous substitution rate) than do the old exons shared by human and mouse, implying a role of positive selection in the rapid evolution. The majority of these new exons have sequences unique in the genome, suggesting that most new exons might originate through "exonization" of intronic sequences. Most of the new exons appear to be alternative exons that are expressed at low levels.

Alternative Splicing↗

PubMed2005

Revised uvulopalatopharyngoplasty with uvula preservation and its clinical study.

OBJECTIVES: A revised uvulopalatopharyngoplasty (UPPP) is reported for reducing the surgical complications without compromising the response. METHODS AND MATERIALS: A new method of performing UPPP was designed, in which the uvula is preserved, but a larger portion of the soft palate is removed. This new procedure is called the 'revised UPPP with uvula preservation' (Han's UPPP or H-UPPP), the characteristics of which are as follows: complete preservation of the uvula; larger portion of the soft palate resected (with the levator palati and tensor palati remaining intact); the adipose tissue in the space of the velum palati is removed; the preserved uvula will become a 'normal' one by the contraction of scar tissue on both sides of the musculus palato-uvularis and the lower margin of the tensor palati. 68 cases of obstructive sleep apnea/hypopnea syndrome had been treated with H-UPPP between September 1998 and May 2001. RESULTS: Polysomnography was performed for all 68 cases 6 months postoperatively with a surgical response of 69.12%, defined as a >50% reduction of the apnea-hypopnea index and <20 apneic pauses/h; no palatopharyngeal incompetency or palatopharyngeal stenosis. Anatomic measurements showed that the preserved uvula in H-UPPP begins to retract 2 weeks postoperatively, and the preserved uvula becomes 'normal' in 3-6 months. CONCLUSIONS: These results suggest that H-UPPP is an effective surgery and produces fewer complications compared with the classic UPPP.

Adipose Tissue↗

PubMed2005

Encapsulation and controlled release of a hydrophobic drug using a novel nanoparticle-forming hyperbranched polyester.

An amphiphilic, hyperbranched polymer suitable for use in controlled drug delivery is reported. This polymer was obtained by modification of the hyperbranched aliphatic polyester Boltorn H20 (H20) with succinic anhydride and then glycidyl methacrylate, and formed nanoparticles in aqueous solution. The critical association concentration was 7.4 x 10(-3) g . L(-1), as determined by fluorescence spectroscopy using pyrene as a molecular probe. A static/dynamic laser light scattering (LLS) study revealed that the average particle size was 39.4 nm with a low particle size distribution (PDI=0.04), and that each particle was composed of about 350 amphiphilic molecules. Daidzein, a hydrophobic traditional Chinese medicine, was encapsulated during particle formation and the release properties were determined. The optimal feeding concentration of daidzein to hyperbranched polyester was 4.9 x 10(-5) g . mL(-1) to 5.0 x 10(-3) g . mL(-1) with a loading efficiency of 76.1%. In the presence of the enzyme Lipase PS, the drug loaded nanoparticles degraded in a random one-by-one manner and released the drug over a few days. This system is therefore a novel controlled drug release system based on nanoparticles formed of hyperbranched polyester. Encapsulation of daidzein by hyperbranched polyester particles.

Capsules↗

PubMed2005

Study of fibrinogen adsorption on self-assembled monolayers on Au(111) by atomic force microscopy.

The adsorption of plasma protein fibrinogen on the self-assembled monolayers (SAMs) of n-hexadecyl mercaptan and citrate was investigated with atomic force microscopy (AFM). On the basis of the preparation of these two flat SAMs on Au(111), high-resolution AFM images of bovine fibrinogen were obtained with different protein concentrations. The results indicated that the surface chemical composition significantly affected the adsorption behavior of fibrinogen. Since fibrinogen plays a key role in the regulation of both haemostasis and thrombosis, high-resolution AFM imaging on SAMs is expected to be an effective approach to study the haemocompatibility of materials with different surface chemistry.

Adsorption↗

PubMed2005

Ethanol alters trafficking and functional N-methyl-D-aspartate receptor NR2 subunit ratio via H-Ras.

The N-methyl-D-aspartate receptor (NMDAR) plays a critical role in synaptic plasticity and is one of the main targets for alcohol (ethanol) in the brain. Trafficking of the NMDAR is emerging as a key regulatory mechanism that underlies channel activity and synaptic plasticity. Here we show that exposure of hippocampal neurons to ethanol increases the internalization of the NR2A but not NR2B subunit of the NMDAR via the endocytic pathway. We further observed that ethanol exposure results in NR2A endocytosis through the activation of H-Ras and the inhibition of the tyrosine kinase Src. Importantly, ethanol treatment alters functional subunit composition from NR2A/NR2B- to mainly NR2B-containing NMDARs. Our results suggest that addictive drugs such as ethanol alter NMDAR trafficking and subunit composition. This may be an important mechanism by which ethanol exerts its effects on NMDARs to produce alcohol-induced aberrant plasticity.

Adaptor Protein Complex 2↗

PubMed2005

Electrolyte-gated transistors based on conducting polymer nanowire junction arrays.

In this study, we describe the electrolyte gating and doping effects of transistors based on conducting polymer nanowire electrode junction arrays in buffered aqueous media. Conducting polymer nanowires including polyaniline, polypyrrole, and poly(ethylenedioxythiophene) were investigated. In the presence of a positive gate bias, the device exhibits a large on/off current ratio of 978 for polyaniline nanowire-based transistors; these values vary according to the acidity of the gate medium. We attribute these efficient electrolyte gating and doping effects to the electrochemically fabricated nanostructures of conducting polymer nanowires. This study demonstrates that two-terminal devices can be easily converted into three-terminal transistors by simply immersing the device into an electrolyte solution along with a gate electrode. Here, the field-induced modulation can be applied for signal amplification to enhance the device performance.

Journal Article↗

PubMed2005

Mammalian cells stably overexpressing N-acylphosphatidylethanolamine-hydrolysing phospholipase D exhibit significantly decreased levels of N-acylphosphatidylethanolamines.

In animal tissues, NAEs (N-acylethanolamines), including N-arachidonoylethanolamine (anandamide), are primarily formed from their corresponding NAPEs (N-acylphosphatidylethanolamines) by a phosphodiesterase of the PLD (phospholipase D) type (NAPE-PLD). Recently, we cloned cDNAs of NAPE-PLD from mouse, rat and human [Okamoto, Morishita, Tsuboi, Tonai and Ueda (2004) J. Biol. Chem. 279, 5298-5305]. However, it remained unclear whether NAPE-PLD acts on endogenous NAPEs contained in the membrane of living cells. To address this question, we stably transfected two mammalian cell lines (HEK-293 and CHO-K1) with mouse NAPE-PLD cDNA, and investigated the endogenous levels and compositions of NAPEs and NAEs in these cells, compared with mock-transfected cells, with the aid of GC-MS. The overexpression of NAPE-PLD caused a decrease in the total amount of NAPEs by 50-90% with a 1.5-fold increase in the total amount of NAEs, suggesting that the recombinant NAPE-PLD utilizes endogenous NAPE as a substrate in the cell. Since the compositions of NAEs and NAPEs of NAPE-PLD-overexpressing cells and mock-transfected cells were very similar, the enzyme did not appear to discriminate among the N-acyl groups of endogenous NAPEs. These results confirm that overexpressed NAPE-PLD is capable of forming NAEs, including anandamide, in living cells.

Animals↗

PubMed2005

Multiscale multifractality analysis of a 12-lead electrocardiogram.

This paper proposes that a multiscale multifractality (MSMF) method be adopted for the spatiotemporal analysis of 12-lead ECG. By using this method, the authors find that, in some frequency range, 12-lead ECG has a more complex fractal structure, and the position of the largest singularity strength range delta alpha is not relying on the data length but on the scale factor. By determining the inflexion, the MSMF proves to be more sensitive in displaying the trend that the singularity strength range delta alpha of human ECG decreases with human aging.

Algorithms↗

PubMed2005

E-Cadherin and beta-Catenin expression in early stage cervical carcinoma: a tissue microarray study of 147 cases.

BACKGROUND: The disruption of intercellular adhesions is an important component of the acquisition of invasive properties in epithelial malignancies. Alterations in the cell-cell adhesion complex, E-Cadherin/beta-Catenin, have been implicated in the oncogenesis of carcinomas arising from various anatomic sites and have been correlated with adverse clinico-pathologic parameters. In this study, the authors investigated the immunohistochemical expression of E-Cadherin and beta-Catenin in a cohort of early stage cervical cancers to determine its prognostic significance and to investigate differences between the three major histological subtypes. PATIENTS AND METHODS: A tissue microarray of 147 cases of FIGO stage 1A and 1B cervical carcinomas [96 squamous cell carcinomas (SCC), 35 adenocarcinomas (AC), 12 adenosquamous carcinomas (ASQ), 4 miscellaneous types] was constructed from our archived surgical pathology files and stained with monoclonal antibodies to E-Cadherin and beta-Catenin. Cases were scored by multiplying the intensity of staining (1 to 3 scale) by the percentage of cells stained (0-100%) for a potential maximum score of 300. For both markers, "preserved" expression was defined as bright membranous staining with a score of 200 or above. "Impaired" expression included any of the following: negative staining, a score less than 200, or exclusively cytoplasmic or nuclear delocalization. RESULTS: Impaired expression of beta-Catenin was found in 85.7%, 66.7%, & 58.3% of AC, SCC & ASQ respectively. Impaired expression of E-Cadherin was found in 94.3%, 86.5% & 100% of cases of AC, SCC, & ASQ respectively. The differences between the histologic subtypes were not significant. For the whole cohort, a comparison of cases showing impaired versus preserved of E-Cadherin and beta-Catenin expression showed no significant differences with respect to recurrence free survival, overall survival, patient age, histologic grade, and frequency of lymphovascular invasion or lymph node involvement. There was no correlation between the status of both markers for all three histological subtypes (overall spearman correlation co-efficient r = 0.12, p = 0.14) CONCLUSION: Impairment of E-Cadherin and beta-Catenin expression is very frequent in early stage cervical cancers, and alterations in the E-Cadherin/beta-Catenin cell adhesion complex are therefore likely involved in the pathogenesis of cervical carcinomas even at their earliest stages. None of the three major histological subtypes of cervical carcinoma (SCC, ADCA, ADSQ) is significantly more likely than the others to show impairment in E-Cadherin and beta-Catenin expression. Overall, the expression of both markers does not significantly correlate with clinico-pathological parameters of prognostic significance.

Journal Article↗

PubMed2005

Immobilized N-alkylated polyethylenimine avidly kills bacteria by rupturing cell membranes with no resistance developed.

Several critical mechanistic and phenomenological aspects of the microbicidal surface coatings based on immobilized hydrophobic polycations, previously developed by us, are addressed. Using Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria, remarkable bactericidal action (up to a 10(9)-fold reduction in live bacteria count in the surface-exposed solution and a 100% inactivation of the surface-adhered bacteria) of an amino-glass slide covalently derivatized with N-hexyl,methyl-polyethylenimine (PEI) is found to be due to rupturing bacterial cell membranes by the polymeric chains. The bacteria fail to develop noticeable resistance to this lethal action over the course of many successive generations. Finally, the immobilized N-alkyl-PEI, while deadly to bacteria, is determined to be harmless to mammalian (monkey kidney) cells.

Animals↗

PubMed2005

Mechanisms of mucosal and parenteral tuberculosis vaccinations: adenoviral-based mucosal immunization preferentially elicits sustained accumulation of immune protective CD4 and CD8 T cells within the airway lumen.

The mechanisms underlying better immune protection by mucosal vaccination have remained poorly understood. In our current study we have investigated the mechanisms by which respiratory virus-mediated mucosal vaccination provides remarkably better immune protection against pulmonary tuberculosis than parenteral vaccination. A recombinant adenovirus-based tuberculosis (TB) vaccine expressing Mycobacterium tuberculosis Ag85A (AdAg85A) was administered either intranasally (i.n.) or i.m. to mice, and Ag-specific CD4 and CD8 T cell responses, including frequency, IFN-gamma production, and CTL, were examined in the spleen, lung interstitium, and airway lumen. Although i.m. immunization with AdAg85A led to activation of T cells, particularly CD8 T cells, in the spleen and, to a lesser extent, in the lung interstitium, it failed to elicit any T cell response in the airway lumen. In contrast, although i.n. immunization failed to effectively activate T cells in the spleen, it uniquely elicited higher numbers of Ag-specific CD4 and CD8 T cells in the airway lumen that were capable of IFN-gamma production and cytolytic activities, as assessed by an intratracheal in vivo CTL assay. These airway luminal T cells of i.n. immunized mice or splenic T cells of i.m. immunized mice, upon transfer locally to the lungs of naive SCID mice, conferred immune protection against M. tuberculosis challenge. Our study has demonstrated that the airway luminal T cell population plays an important role in immune protection against pulmonary TB, thus providing mechanistic insights into the superior immune protection conferred by respiratory mucosal TB vaccination.

Acyltransferases↗

PubMed2005

Relations between plasma asymmetric dimethylarginine (ADMA) and risk factors for coronary disease.

BACKGROUND: Elevated plasma levels of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide production, are reported to be associated with coronary artery disease (CAD). METHODS: We measured plasma levels of ADMA and related compounds, nitrate+nitrite (NO(x)), total homocysteine (tHCY) and assessed renal function and lipid profiles in 145 patients--75 with triple vessel coronary disease and 70 with no detectable coronary disease. RESULTS: Levels of ADMA, l-arginine, l-arginine/ADMA and plasma NO(x) were not different in the two groups but smokers with triple vessel disease had higher ADMA and lower NO(x) levels than the non-smokers, relationships also present for all smokers and non-smokers in the two groups combined. In all 145 patients ADMA, symmetric dimethylarginine (SDMA) and tHCY levels were significantly higher in patients with glomerular filtration rate (GFR) <81 mL/min/1.73 m(2) than in patients with GFR> or =81 mL/min/1.73 m(2). There was a modest positive correlation between tHCY and ADMA and both were strongly correlated with SDMA which is excreted by the kidney. ADMA, SDMA and tHCY were negatively correlated with GFR. CONCLUSIONS: We suggest that the reported ADMA increases in CAD patients are due to an associated reduction in renal function and to smoking habit.

Adult↗

PubMed2005

Aptamer-based ATP assay using a luminescent light switching complex.

With the increasing applications of nucleic acid aptamers as a new class of molecular recognition probes in bioanalysis and biosensor development, the development of general and simple signaling strategies to transduce aptamer-target binding events to detectable signals is demanding. We have developed a new signaling method based on aptamers and a DNA molecular light switching complex, [Ru(phen)2(dppz)]2+, for sensitive protein detection. In this work, we have demonstrated the applicability of this signaling mechanism to small-molecule detection using ATP as a model target. Our results have shown that upon ATP binding to the folded aptamer where [Ru(phen)2(dppz)]2+ intercalated, the conformational change or distortion of the aptamer is large enough to cause a significant luminescence change of [Ru(phen)2(dppz)]2+. By monitoring the ATP-dependent luminescence intensity change, we have achieved ATP detection with high selectivity and high sensitivity down to 1 nM in homogeneous solution. The method is very simple without the needs for covalently labeling aptamers or using costly enzymes and multistep analysis as other reported fluorescence/luminescence assays for ATP. The successful detection of ATP indicates that using the signaling aptamers with [Ru(phen)2(dppz)]2+ is expected to be a general method for aptamer-based target detection.

Adenosine Triphosphate↗

PubMed2005

Tiling microarray analysis of rice chromosome 10 to identify the transcriptome and relate its expression to chromosomal architecture.

BACKGROUND: Sequencing and annotation of the genome of rice (Oryza sativa) have generated gene models in numbers that top all other fully sequenced species, with many lacking recognizable sequence homology to known genes. Experimental evaluation of these gene models and identification of new models will facilitate rice genome annotation and the application of this knowledge to other more complex cereal genomes. RESULTS: We report here an analysis of the chromosome 10 transcriptome of the two major rice subspecies, japonica and indica, using oligonucleotide tiling microarrays. This analysis detected expression of approximately three-quarters of the gene models without previous experimental evidence in both subspecies. Cloning and sequence analysis of the previously unsupported models suggests that the predicted gene structure of nearly half of those models needs improvement. Coupled with comparative gene model mapping, the tiling microarray analysis identified 549 new models for the japonica chromosome, representing an 18% increase in the annotated protein-coding capacity. Furthermore, an asymmetric distribution of genome elements along the chromosome was found that coincides with the cytological definition of the heterochromatin and euchromatin domains. The heterochromatin domain appears to associate with distinct chromosome level transcriptional activities under normal and stress conditions. CONCLUSION: These results demonstrated the utility of genome tiling microarray in evaluating annotated rice gene models and in identifying novel transcriptional units. The tiling microarray sanalysis further revealed a chromosome-wide transcription pattern that suggests a role for transposable element-enriched heterochromatin in shaping global transcription in response to environmental changes in rice.

Chromosomes, Plant↗

PubMed2005

TNF-alpha promotes Doxorubicin-induced cell apoptosis and anti-cancer effect through downregulation of p21 in p53-deficient tumor cells.

p53 is a key regulator in cell apoptosis, and cancer cells deficient in p53 expression fail to respond to chemotherapy. Here we show that effective Doxorubicin (DOX)-induced apoptosis is p53-dependent. However, an alternative treatment of DOX/TNF-alpha/DOX restored sensitivity of p53-deficient cells to DOX-induced apoptosis. Treatment of cells with TNF-alpha resulted in a decrease of p21 (waf1/cip1/sdi1) expression following second dose of DOX. In previous work, we demonstrated that p21 suppressed DOX-induced apoptosis via its (cyclin-dependent kinase) CDK-binding and CDK-inhibitory activity. Thus, we propose that TNF-alpha enhances the anti-cancer effect of DOX through suppressing the anti-apoptotic activity of p21, and that a combined treatment TNF-alpha/Dox is an effective chemotherapeutic strategy for p53-deficient cancers.

Antineoplastic Agents↗

PubMed2005

[Video-assisted thoracoscopic extended thymectomy for myasthenia gravis: analysis of 107 cases].

OBJECTIVE: To evaluate the results of video-assisted thoracoscopic extended thymectomy for myasthenia gravis. METHODS: We retrospectively reviewed data from 107 patients received thoracoscopic extended thymectomy from June 1995 to June 2004. All patients had confirmed diagnosis of myasthenia gravis by clinical manifestation and electromyogram. Thoracoscopic extended thymectomy as well as dissection of all fatty tissue anterior to the pericardium was performed. RESULTS: During a follow-up of 1-98 months, symptom was significantly improved in 83% of patients, including 34 patients experienced complete remission. There was no postoperative mortality. CONCLUSION: Favorable results of video-assisted thoracoscopic extended thymectomy can be achieved in patients with myasthenia gravis. The technique is safe and minimally invasive.

Adolescent↗