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Biomedical subjects

Fei Huang

Publications and source records attributed to Fei Huang.

16 recordsLinked to original sources
PubMed2005

Synthesis and properties of electrophosphorescent chelating polymers with iridium complexes in the conjugated backbone.

The synthesis of electrophosphorescent chelating polymers by Suzuki polycondensation of A-A- and B-B-type monomers is described, in which the fluorene-alt-carbazole (PFCz) segment is used as polymer backbone. By using alkyl-substituted ligands of iridium complex monomers, chelating copolymers with higher contents of iridium complex can be synthesized. Chemical and photophysical characterization confirm that the Ir complex is incorporated into the polymer backbone as one of the monomer repeat units by means of two 5-bromotolylpyridine ligands. Chelating polymers with Ir complexes in the conjugated polymer backbone show highly efficient energy transfer of excitons from the PFCz host segment to the Ir complex by an intramolecular trapping mechanism. The external quantum and luminous efficiencies of a device made with PFCzMppyIrhm4 copolymer reach 4.1 % ph/el (photons/electron) and 5.4 cd A(-1), respectively, at a current density of 32.2 mA cm(-2), an emission peak of 577 nm, and a luminance of 1730 cd cm(-2). Most important, the devices made from the chelating copolymers show no notable efficiency decay with increasing current density due to reduced concentration quenching and triplet-triplet (T-T) annihilation. This indicates that incorporation of the phosphorescent complex into the rigid conjugated polymer main chain is a new way to simultaneously realize high efficiency, long-term stability, and simple processing of phosphorescent polymer light-emitting diodes.

Journal Article↗
PubMed2005

Magnetically assisted DNA assays: high selectivity using conjugated polymers for amplified fluorescent transduction.

We report a strategy for conjugated polymer (CP)-based optical DNA detection with improved selectivity. The high sensitivity of CP-based biosensors arises from light harvesting by the CP and the related amplified fluorescent signal transduction. We demonstrate that the use of magnetic microparticles significantly improves the selectivity of this class of DNA sensors. Compared with previously reported DNA sensors with CP amplification, this novel sensing strategy displays excellent discrimination against non-cognate DNA in the presence of a protein mixture or even human serum. We also demonstrate that the magnetically assisted DNA sensor can conveniently identify even a single-nucleotide mismatch in the target sequence.

Base Pair Mismatch↗
PubMed2005

Tissue hyperoxygenation promotes oxidative metabolism in motor unit.

Some mutant hemoglobin (Hb) variants are found with lowered O2 affinity. Low oxygen affinity is reported to increase the O2 availability in peripheral tissues (Kunert et al. [1996] Microvasc. Res. 52:58-68). In the present study, we used a mouse model carrying two low-affinity Hb variants, Titusville and Presbyterian, to evaluate the chronic in vivo influence of lowered oxygen affinity on the neuromuscular system. Our model mice showed an increased voluntary running ability compared with wild-type littermates. In the tibialis anterior (TA) muscle of mutant mice, the glycolytic fibers were converted to oxidative ones in where the activity of the mitochondrial marker enzyme succinate dehydrogenase (SDH) was up-regulated. We report that the spinal ventral horn motoneurons innervating TA skeletal fibers also showed higher mitochondrial oxidative enzyme activity. This phenomenon was evidenced by increased SDH activity and electron microscopic (EM) mitochondrial electronic density in these motoneurons. Our data suggest that, as the result of adaptation to the tissue hyperoxygenation, energy metabolism in the neuron-muscle motor unit is augmented and thus function of the motor unit is promoted.

Adenosine Triphosphatases↗
PubMed2005

Lysophosphatidylcholine increases endothelial permeability: role of PKCalpha and RhoA cross talk.

Lysophosphatidylcholine (LPC) is a bioactive proinflammatory lipid that can be generated by pathological activities. We investigated the hypothesis that LPC signals increase in endothelial permeability. Stimulation of human dermal microvascular endothelial cells and bovine pulmonary microvascular endothelial cells with LPC (10-50 microM) induced decreases (within minutes) in transendothelial electrical resistance and increase of endothelial permeability. LPC activated (within 5 min) membrane-associated PKC phosphotransferase activity in the absence of translocation. Affinity-binding analysis indicated that LPC induced increases (also by 5 min) of GTP-bound RhoA, but not Rac1 or Cdc42. By 60 min, both signaling pathways decreased toward baseline. Inhibition of RhoA with C3 transferase inhibited approximately 50% of LPC-induced resistance decrease. Pretreatment with PKC inhibitor Gö-6983 (concentrations selective for classic PKC), PMA-induced depletion of PKCalpha, and transfection of antisense PKCalpha oligonucleotide each prevented 40-50% of the LPC-induced resistance decrease. Furthermore, these three PKC inhibition strategies inhibited 60-80% of the LPC-induced GTP-bound RhoA. These results show that LPC directly impairs the endothelial barrier function that was dependent, at least in part, on cross talk of PKCalpha and RhoA signals. The evidence indicates that elevated LPC levels can contribute to the activation of a proinflammatory endothelial phenotype.

Animals↗
PubMed2005

[Development and applications of dendrimers in biomedicine].

Dendrimers are new macromolecules synthesized in recent years, which are of great interests in many fields where they have potential important applications because of their hyperbranched, well defined and monodisperse structures. In this paper, the unique structures, general synthesis routes and basic physical and chemical properties of dendrimers are introduced in brief, and the progress in the research of dendrimers in drug (gene) delivery, contrast agents, cancer therapy were reviewed, as well as the perspective in research and applications.

Contrast Media↗
PubMed2004

IL-17 markedly up-regulates beta-defensin-2 expression in human airway epithelium via JAK and NF-kappaB signaling pathways.

Using microarray gene expression analysis, we first observed a profound elevation of human beta-defensin-2 (hBD-2) message in IL-17-treated primary human airway epithelial cells. Further comparison of this stimulation with a panel of cytokines (IL-1alpha, 1beta, 2-13, and 15-18; IFN-gamma; GM-CSF; and TNF-alpha) demonstrated that IL-17 was the most potent cytokine to induce hBD-2 message (>75-fold). IL-17-induced stimulation of hBD-2 was time and dose dependent, and this stimulation also occurred at the protein level. Further studies demonstrated that hBD-2 stimulation was attenuated by IL-17R-specific Ab, but not by IL-1R antagonist or the neutralizing anti-IL-6 Ab. This suggests an IL-17R-mediated signaling pathway rather than an IL-17-induced IL-1alphabeta and/or IL-6 autocrine/paracrine loop. hBD-2 stimulation was sensitive to the inhibition of the JAK pathway, and to the inhibitors that affect NF-kappaB translocation and the DNA-binding activity of its p65 NF-kappaB subunit. Transient transfection of airway epithelial cells with an hBD-2 promoter-luciferase reporter gene expression construct demonstrated that IL-17 stimulated promoter-reporter gene activity, suggesting a transcriptional mechanism for hBD-2 induction. These results support an IL-17R-mediated signaling pathway involving JAK and NF-kappaB in the transcriptional stimulation of hBD-2 gene expression in airway epithelium. Because IL-17 has been identified in a number of airway diseases, especially diseases related to microbial infection, these findings provide a new insight into how IL-17 may play an important link between innate and adaptive immunity, thereby combating infection locally within the airway epithelium.

Animals↗
PubMed2004

High-efficiency, environment-friendly electroluminescent polymers with stable high work function metal as a cathode: green- and yellow-emitting conjugated polyfluorene polyelectrolytes and their neutral precursors.

A series of aminoalkyl-substituted polyfluorene copolymers with benzothiadiazole (BTDZ) of different content were synthesized by Suzuki coupling reaction, and their quaternized ammonium polyelectrolyte derivatives were obtained through a postpolymerization treatment on the terminal amino groups. Copolymers are soluble in environmentally friendlier solvents, such as alcohols. It was found that the efficient energy transfer occurs by exciton trapping on the narrow band gap BTDZ site under UV illumination. Only 1% of BTDZ content is needed to completely quench a fluorene emission for both the neutral and the quaternized copolymers in the neat film. Absolute PL efficiencies of copolymer films were greatly enhanced as a result of the suppression of excimer formation. Light-emitting devices fabricated from these copolymers show high external quantum efficiencies over 3% and 1% for the neutral precursor and the quaternized copolymers, respectively, with high work function metals such as Al as a cathode. To the best of our knowledge, this is the first report on an electroluminescent polymer which bears the high EL efficiency, the electron-injection ability from high work function metals, and the solubility in environment-friendly solvents at the same time. These features make them a promising candidate for the next generation of light-emitting copolymers in PLED flat panel display application.

Journal Article↗
PubMed2004

Colorectal cancers with microsatellite instability display mRNA expression signatures characteristic of increased immunogenicity.

BACKGROUND: Colorectal cancers displaying high-degree microsatellite instability (MSI-H) have an improved prognosis compared to microsatellite stable (MSS) cancers. The observation of pronounced lymphocytic infiltrates suggests that MSI-H cancers are inherently more immunogenic. We aimed to compare the gene expression profiles of MSI-H and MSS cancers to provide evidence for an activated immune response in the former. RESULTS: We analysed tissue from 133 colorectal cancer patients with full consent and Local Ethics Committee approval. Genomic DNA was analysed for microsatellite instability in BAT-26. High-quality RNA was used for microarray analysis on the Affymetrix HG-U133A chip. Data was analysed on GeneSpring software version 6.0. Confirmatory real-time RT-PCR was performed on 28 MSI-H and 26 MSS cancers. A comparison of 29 MSI-H and 104 MSS cancers identified 2070 genes that were differentially expressed between the two groups [P < 0.005]. Significantly, many key immunomodulatory genes were up-regulated in MSI-H cancers. These included antigen chaperone molecules (HSP-70, HSP-110, Calreticulin, gp96), pro-inflammatory cytokines (Interleukin (IL)-18, IL-15, IL-8, IL-24, IL-7) and cytotoxic mediators (Granulysin, Granzyme A). Quantitative RT-PCR confirmed up-regulation of HSP-70 [P = 0.016], HSP-110 [P = 0.002], IL-18 [P = 0.004], IL-8 [0.002] and Granulysin [P < 0.0001]. CONCLUSIONS: The upregulation of a large number of genes implicated in immune response supports the theory that MSI-H cancers are immunogenic. The novel observation of Heat Shock Protein up-regulation in MSI-H cancer is highly significant in light of the recognised roles of these proteins in innate and antigen-specific immunogenicity. Increased mRNA levels of pro-inflammatory cytokines and cytotoxic mediators also indicate an activated anti-tumour immune response.

Colorectal Neoplasms↗
PubMed2003

Inflammatory stress increases receptor for lysophosphatidylcholine in human microvascular endothelial cells.

The atherogenic serum lysophosphatidylcholine (LPC) is known to mediate vascular endothelial responses ranging from upregulation of adhesion molecules and growth factors to secretion of chemokines and superoxide anion. We investigated whether endothelial cells express receptors for LPC, which may account for their actions. Human brain microvascular (HBMEC) and dermal microvascular endothelial cells (HMEC) were prepared for RT-PCR analysis for possible expression of the G protein-coupled receptors, GPR4 and G2A, which are believed to be specific LPC receptors. Results indicated that HBMEC expressed low basal GPR4 mRNA, but stimulation with tumor necrosis factor-alpha (TNF-alpha) (100 U/ml) or H2O2 (50 micromol/l) for 2 h or overnight upregulated expression severalfold. In contrast, HMEC expressed high basal GPR4 mRNA, which was not further increased by either TNF-alpha or H2O2 stimulation. Another LPC receptor, G2A, was not detected in either endothelial cell type. Competition binding studies were made to evaluate specific binding of [3H]LPC to the intact endothelial cell monolayer. Basal specific [3H]LPC binding in HBMEC was approximately eight times lower than in HMEC; however, TNF-alpha or H2O2 stimulation increased [3H]LPC binding on HMBEC but not HMEC. The results indicated that GPR4 expression was consistent with specific [3H]LPC binding. Overall, we report that endothelial cells selectively expressed GPR4, a specific LPC receptor. Furthermore, GPR4 expression by HBMEC, but not HMEC, was increased by inflammatory stresses. We conclude that endogenous GPR4 in endothelial cells may be a potential G protein-coupled receptor by which LPC signals proinflammatory activities.

Cell Cycle Proteins↗
PubMed2003

PKA inhibits RhoA activation: a protection mechanism against endothelial barrier dysfunction.

Much evidence indicates that cAMP-dependent protein kinase (PKA) prevents increased endothelial permeability induced by inflammatory mediators. We investigated the hypothesis that PKA inhibits Rho GTPases, which are regulator proteins believed to mediate endothelial barrier dysfunction. Stimulation of human microvascular endothelial cells (HMEC) with thrombin (10 nM) increased activated RhoA (RhoA-GTP) within 1 min, which remained elevated approximately fourfold over control for 15 min. The activation was accompanied by RhoA translocation to the cell membrane. However, thrombin did not activate Cdc42 or Rac1 within similar time points, indicating selectivity of activation responses by Rho GTPases. Pretreatment of HMEC with 10 micro M forskolin plus 1 micro M IBMX (FI) to elevate intracellular cAMP levels inhibited both thrombin-induced RhoA activation and translocation responses. FI additionally inhibited thrombin-mediated dissociation of RhoA from guanine nucleotide dissociation inhibitor (GDI) and enhanced in vivo incorporation of (32)P by GDI. HMEC pretreated in parallel with FI showed >50% reduction in time for the thrombin-mediated resistance drop to return to near baseline and inhibition of approximately 23% of the extent of resistance drop. Infection of HMEC with replication-deficient adenovirus containing the protein kinase A inhibitor gene (PKA inhibitor) blocked both the FI-mediated protective effects on RhoA activation and resistance changes. In conclusion, the results provide evidence that PKA inhibited RhoA activation in endothelial cells, supporting a signaling mechanism of protection against vascular endothelial barrier dysfunction.

Adenoviridae↗
PubMed2003

Antibiotic sensitivity and biochemical characterization of Fusobacterium spp. and Arcanobacterium pyogenes isolated from farmed white-tailed deer (Odocoileus virginianus) with necrobacillosis.

Bacterial cultures from 32 living and dead farmed white-tailed deer (Odocoileus virginianus) with necrobacillosis yielded Fusobacterium necrophorum from nine individuals, F. varium from six individuals, and Arcanobacterium pyogenes from 16 individuals. The isolates were characterized biochemically using automated identification systems. Gram-stained smears suggested the presence of Fusobacterium spp. in eight cases from which organisms were not cultured. Minimum inhibitory concentration determinations in 23 strains of gram-negative anaerobic bacteria detected resistance to enrofloxacin and clindamycin. Enrofloxacin resistance was detected in A. pyogenes isolates, and although biochemical profiling indicated that the deer strains of A. pyogenes could be grouped, it is uncertain whether these biochemical characteristics correlate with antigenic or virulence factors. Deer-specific or autogenous vaccines may provide a useful alternative to generic vaccines.

Actinomycetaceae↗
PubMed2003

Comparison of bacterial enriched-broth culture, enzyme linked immunosorbent assay, and broth culture-polymerase chain reaction techniques for identifying asymptomatic infections with Salmonella in swine.

A polymerase chain reaction (PCR) assay was combined with a broth-culture enrichment system to detect Salmonella shed in feces from subclinically infected swine. The effectiveness of the broth culture-polymerase chain reaction (BC-PCR) assay to identify pigs shedding Salmonella in feces was compared with a microbiological culture and a commercial enzyme linked immunosorbent assay (ELISA) kit to detect Salmonella-specific serum antibody. A total of 67 pigs were tested by each of the 3 methodologies. Forty-one pigs tested positive for Salmonella by BC-PCR and ELISA identified 6 positives and 23 suspicious samples. It was shown that the BC-PCR assay is a rapid diagnostic tool for detecting of Salmonella shed by asymptomatic swine compared with current diagnostic technologies.

Animals↗
PubMed2003

[Early intravenous thrombolysis with recombinant tissue plasminogen activator for acute cerebral infarction].

OBJECTIVE: To evaluate the efficacy and safety of recombinant tissue plasminogen activator (rt-PA) and to explore the most suitable dosage of rt-PA in the early treatment of the Chinese patients with acute cerebral infarction (ACI). METHODS: The patients who suited for the standard were divided into three groups. Group A received rt-PA at 0.9 mg/kg, group B received rt-PA at 0.7 mg/kg, and group C did not receive any thrombolytic therapy. In thrombolytic groups, rt-PA at 8 mg was injected intravenously in a bolus at first and then the rest was given over 60 minutes. The maximal dosage was 90 mg. The Chinese stroke scale (CSS) and Barthel Index (BI) were used to evaluate the recovery of neurological functions after rt-PA treatment for 24 hours and 90 days. The hemorrhagic rate and 30 days mortality rate were also analysed. RESULTS: In group A the CSS significant effective rate was 41.18 percent at 24 hours and 76.47 percent at 90 days after thrombolysis. At 90 days BI significant effective rate was 58.82 percent. At 30 days hemorrhagic rate was 8.82 percent and mortality rate was 5.88 percent. In group B, the CSS significant effective rate was 39.39 percent at 24 hours and 69.70 percent at 90 days. At 90 days, BI significant effective rate was 54.55 percent, and at 30 days, hemorrhagic rate was 9.09 percent and mortality rate was 9.09 percent. In group C, the CSS significant effective rate was 21.21 percent, at 24 hours and 30.30 percent at 90 days (P>0.05). At 90 days, BI was 21.21 percent the mortality rate was 9.09 percent. At 30 days the mortality rate was no significant difference within three groups At 90 days, significant effective rate was 73.13 percent vs. 30.30 percent in thrombolytic and control groups (P=0.001 7). The significant disability rate was 13.43 percent vs. 24.24 percent. CONCLUSION: For Chinese individuals, with ACI, rt-PA thrombolysis was effective and safe. The dosage of 0.9 mg/kg for foreign people also fitted for Chinese individuals.

Acute Disease↗
PubMed2002

Oxygen affinity of hemoglobin regulates O2 consumption, metabolism, and physical activity.

The oxygen affinity of hemoglobin is critical for gas exchange in the lung and O(2) delivery in peripheral tissues. In the present study, we generated model mice that carry low affinity hemoglobin with the Titusville mutation in the alpha-globin gene or Presbyterian mutation in the beta-globin gene. The mutant mice showed increased O(2) consumption and CO(2) production in tissue metabolism, suggesting enhanced O(2) delivery by mutant Hbs. The histology of muscle showed a phenotypical conversion from a fast glycolytic to fast oxidative type. Surprisingly, mutant mice spontaneously ran twice as far as controls despite mild anemia. The oxygen affinity of hemoglobin may control the basal level of erythropoiesis, tissue O(2) consumption, physical activity, and behavior in mice.

Animals↗
PubMed2002

[Transferring of the pedicled second metatarsal base for repairing bone defect of lateral malleolus].

OBJECTIVE: To study the method and effect of transferring the pedicled second metatarsal base for repairing bone defect of lateral malleolus. METHODS: Thirty lower limb specimens were anatomized to observe the morphology, structure and blood supply of the second metatarsal bone. Then transferring of the pedicled second metatarsal base was designed and used in 6 patients clinically. All cases were male, aged from 24 to 48 years old, and the area of bone defect was 3-4 cm. RESULTS: Followed up for 3-11 months, all patients healed primarily both in donor and recipient sites. There were excellent results in 4 cases and good results in 2 cases. The morphology and function of the malleoli were satisfactory. CONCLUSION: Transferring of the pedicled second metatarsal base for repairing bone defect of lateral malleolus is an effective and reliable operative method.

Adult↗