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Biomedical subjects

Feng Qiu

Publications and source records attributed to Feng Qiu.

At least 19 recordsLinked to original sources
PubMed2007

Antipsychotic use in older adults with Parkinson's disease.

The choice of agents to treat psychotic symptoms in Parkinson's disease is important given the potential for antipsychotics to worsen Parkinsonism. The purpose of this study was to estimate the incidence of psychotic symptoms requiring treatment in individuals with Parkinson's disease after starting dopaminergic medications, and to describe the agents being selected as initial antipsychotic therapy. Using the administrative health care databases of Ontario, Canada, individuals 66 years of age or older with Parkinson's disease who were newly treated with dopaminergic agents were identified. Subsequent prescriptions for antipsychotic medications were then identified. A total of 10,347 older adults were newly started on dopaminergic agents between 1998 and 2003. The Kaplan-Meier estimate for the cumulative probability of requiring an antipsychotic at 7 years was 35%; 499 individuals (4.8%; 5.2/100 person-years) were prescribed an antipsychotic within 1 year of starting dopaminergic therapy. The proportion of initial antipsychotic prescriptions for typical antipsychotics decreased from 56% (42 of 75) in 1998 to 9% (8 of 88) in 2002. Antipsychotic use is common in individuals with Parkinsonism newly treated with dopaminergic medication. Typical antipsychotics are still commonly being chosen as first-line agents for older patients, indicating a need for interventions to improve practice.

Aged↗
PubMed2006

Shape of fluid vesicles anchored by rigid rod.

A method combined the self-consistent field theory (SCFT) for the rigid rod with the Helfrich curvature elasticity theory for the vesicle has been developed for studying the shape of vesicles anchored by rigid rod. Both the deformation of the vesicle and the density distribution of rod segments can be obtained. Because of the vesicle's impenetrability for the rod segments and the decrease of the available space for the rod orientational configurations, the anchored rod segments exert the inhomogeneous entropic pressure on the vesicle and induce the change of vesicle shape. The interaction between the rod segments and the vesicle membrane exerts an extra tension to the membrane. Thus the interaction between the vesicle membrane and the rod segments, the rod length, and the bending rigidity of vesicle are investigated as the important factors to the shape transformation of the vesicle and the density distribution of rod segments. This method can be extended to more complicated and real biological systems, such as polymers with different topological architectures/vesicle, multiple chains/vesicle, protein inclusions, etc.

Algorithms↗
PubMed2006

Self-assembly of gradient concentric rings via solvent evaporation from a capillary bridge.

A drop of solution containing nonvolatile solute is allowed to evaporate from a sphere-on-flat geometry. Left behind is a striking pattern of gradient concentric rings with unprecedented regularity. The center-to-center distance between adjacent rings, lambda(C-C), and the height of the ring, h(d), are strongly affected by the concentration of the solution and the properties of the solvent. The nature of the formation of regular gradient ring patterns during the course of irreversible solvent evaporation is revealed through theoretical calculations based on the mass conservation of the solution.

Journal Article↗
PubMed2006

Aggregates in solution of binary mixtures of amphiphilic diblock copolymers with different chain length.

The polydispersity effect of amphiphilic AB diblock copolymers on the self-assembled morphologies in solution has been investigated by the real-space implementation of self-consistent field theory (SCFT) in two dimensions (2D). The polydispersity is artificially obtained by mixing binary diblock copolymers where the hydrophilic or hydrophobic blocks are composed of two different lengths while the other block length is kept the same. The main advantage is that this simple polydispersity can easily distinguish the difference of aggregates in the density distribution of long and short block length intuitionally and quantitatively. The morphology transition from vesicles to micelles is observed with increasing polydispersity of copolymers due to the length segregation of copolymers. For polydisperse hydrophilic or hydrophobic blocks, the short blocks tend to distribute at the interfaces between hydrophilic and hydrophobic blocks while the long blocks stretch to the outer space. More specifically, by quantitatively taking the sum of all the concentration distribution of long and short chains over the inside and outside surface areas of the vesicle, it is found that long blocks prefer to locate on the outside surface of the vesicle while short ones prefer the inside. Such length segregation leads to large curvature of the aggregate, thus resulting in the decrease of the aggregate size.

Journal Article↗
PubMed2006

The rapid uptake of concurrent chemotherapy for cervix cancer patients treated with curative radiation.

PURPOSE: In 1999, a series of clinical trials along with a clinical announcement from the National Cancer Institute (NCI) suggested that chemotherapy should be used concurrently with pelvic radiation in the management of cervical cancer. The purpose of this study is to examine the rate of chemotherapy use, in the province of Ontario, before and after these publications. METHODS: All incident cases of cervix cancer diagnosed between January 1, 1995, and March 31, 2001, were identified using the provincial cancer registry. These records were electronically linked to billing claims data and inpatient discharge abstract data. Patients receiving brachytherapy within 6 months of diagnosis were identified. The proportion receiving at least one injection of chemotherapy before brachytherapy was identified and compared in the "pre" and "post" publication group (April 1, 1999, cutoff). RESULTS: We identified 1039 cases as receiving curative radiation. In the pre cohort, 9.4% of patients received chemotherapy (95% CI, 7.3-11.4%) vs. 67.4% in the post cohort (95% CI, 61.8-73.0%). The change occurred abruptly in the first quarter of 1999. CONCLUSION: There was a significant increase in chemotherapy use after the publication of the NCI alert and related trials. Reasons for rapid uptake are discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Ptf1a determines horizontal and amacrine cell fates during mouse retinal development.

The vertebrate neural retina comprises six classes of neurons and one class of glial cells, all derived from a population of multipotent progenitors. There is little information on the molecular mechanisms governing the specification of cell type identity from multipotent progenitors in the developing retina. We report that Ptf1a, a basic-helix-loop-helix (bHLH) transcription factor, is transiently expressed by post-mitotic precursors in the developing mouse retina. Recombination-based lineage tracing analysis in vivo revealed that Ptf1a expression marks retinal precursors with competence to exclusively produce horizontal and amacrine neurons. Inactivation of Ptf1a leads to a fate-switch in these precursors that causes them to adopt a ganglion cell fate. This mis-specification of neurons results in a complete loss of horizontal cells, a profound decrease of amacrine cells and an increase in ganglion cells. Furthermore, we identify Ptf1a as a primary downstream target for Foxn4, a forkhead transcription factor involved in the genesis of horizontal and amacrine neurons. These data, together with the previous findings on Foxn4, provide a model in which the Foxn4-Ptf1a pathway plays a central role in directing the differentiation of retinal progenitors towards horizontal and amacrine cell fates.

Amacrine Cells↗
PubMed2006

[Studies on flavonoids of Andrographis paniculata].

OBJECTIVE: To study the flavonoids of the aerial parts of Andrographis paniculata. METHOD: Twelve flavonoids from the 85% EtOH extract were isolated by the silica gel column, Sephadex LH-20 column, ODS column chromatography and HPLC, and their structures were identified by the spectal analyses and chemical evidences. RESULT: The 12 compounds were obtained and identified as 7-O-methylwogonin (1), 7-O-methyldihydrowogonin (2), 5-hydroxy-7, 8, 2', 5'-tetramethoxy-flavone (3), skullcapflavone-2'-methoxylether (4), 5-hydroxy-7, 8, 2', 3'-tetramethoxyflavone (5), 5, 4'-dihydroxy-7, 8, 2', 3'-tetramethoxyflavone (6), dihydroskullcapflavone (7), 5, 7, 8-trimethoxydihydroflavone (8), 5, 2'-dihydroxy-7, 8-dimethoxyflvone (9), andrographidine C (10), 5, 7, 4'-trihydroxyflavone (11), 5, 7, 3', 4'-tetrahydroxyflavone (12). CONCLUSION: Compound 6 is a new naturally occurring product isolated from A. paniculata, and compound 8, 11 and 12 are obtained for the first time from the Andrographis species.

Andrographis↗
PubMed2006

[Phase II trial of prolonged infusion of low-dose gemcitabine in advanced non-small cell lung cancer treatment].

BACKGROUND & OBJECTIVE: Gemcitabine combined with cisplatin has been taken as the front-line regimen for patients with advanced non-small-cell lung cancer (NSCLC). The routine use of gemcitabine is intravenous injection of a dose of 1,000 mg/m(2) within 30 minutes on days 1 and 8, and the treatment is repeated every 3 weeks. This study was to evaluate the efficacy and safety of 6-hour continuous infusion of low dose of gemcitabine plus cisplatin for patients with advanced NSCLC. METHODS: Forty-eight patients with measurable stage III B/IV NSCLC and without chemotherapy were enrolled. All of them received 6-hour continuous infusion of gemcitabine 250 mg/m(2) on day 1 and 8 plus cisplatin 75 mg/m(2) on day 2-4 for more than 2 cycles. The cycle was repeated every 3 weeks. RESULTS: All 48 patients were evaluated for toxicity and 46 for response. The overall response rate was 32.5% (completed and partial response rates were 2.2% and 30.3%, respectively). The median time to progression was 5.1 months, median survival time was 10.2 months; and 1-year survival rate was 36.6%. The main hematologic toxicity consisted of 60.4% neutropenia, 39.5% thrombocytopenia. Grade III-IV neutropenia and thrombocytopenia were 20.8% and 12.5%, respectively. CONCLUSION: Six-hour prolonged infusion of low dose gemcitabine combined with cisplatin is a relatively safe and effective regimen for patients with advanced NSCLC.

Adult↗
PubMed2006

[Comparative proteome analysis of hepatoma cells at subcellular level].

The subcellular proteome strategy can complement the separation power of two-dimensional electrophoresis, a step for subcellular fractionation is introduced before electrophoresis is conducted, and more proteins will be displayed in two-dimensional gels. A comparative analysis of proteomic profiling of mitochondria and nuclei was conducted between hepatoma cell and hepatocyte, in order to find more information involved in cancer development. The cultured hepatoma cell line QGY-7703 and hepatocyte line LO2 were used as research models in this work. Subcellular fractionation for mitochondrion and nucleus were done by ultracentrifugation, then two-dimensional electrophoresis was applied to the separation of mitochondrial and nuclear proteins, imaging analysis for the selection of differentially-expressed protein spots, and MALDI-TOF-MS for the identification of proteins. 54 spots from electrophoresis gels were selected as differentially-expressed protein for MS analysis which resulted in identification for 22 proteins. Among the 22 differentially-expressed proteins, 17 show a up-regulated expression and 5 show a down-regulated expression. These differentially-expressed proteins found in this work have a wide coverage of functions which are related to energy metabolism, cytosheleton, protein biosynthesis, pre-mRNA splicing and processing, apoptosis regulation. These results imply that cancer cell has experienced a fundamental change in structure and metabolism pattern.

Carcinoma, Hepatocellular↗
PubMed2006

[Proteomic approach to the effect of epirubicin on hepatoma cells at subcellular level].

Epirubicin is an antineoplastic agent known as an anthracycline. It acts directly on DNA by blocking its replication and transcription, so apoptosis can be induced for cancer cells. The protein expression of cancer cells will be altered due to the induction of pharmacological action of epirubicin, so it is important to pay attention to the altered profiling of proteins. Here proteomic strategy was applied to the hepatoma cells at subcellular level, comparative proteome analysis of mitochondria and nucleus were conducted between the hepatoma cells administered with epirubicin and the not-administered. Centrifugation was used for the subcellular fractionation, then 2-DE for the separation of proteins, imaging analysis for the diction of expression-altered spots, and MALDI-TOF-MS for the identification of proteins. In total, 15 proteins were found to have altered their expression after the induction of epirubicin, among them, 5 proteins showed up-regulated expression and 10 showed down-regulated expression. These altered proteins are involved in life processes of cells such as energy metabolism, protein biosynthesis, structure of cell skeleton, processing and maturation of mRNA, heat shock of cells and apoptosis.

Carcinoma, Hepatocellular↗
PubMed2006

[Studies on diterpenoids from Andrographis paniculata].

OBJECTIVE: To study the diterpenoids in the 85% ethanol extract of the aerial parts of Andrographis paniculata. METHOD: Fourteen diterpenoids from the 85% EtOH extract were isolated by the silica gel, Sephadex LH-20, ODS column chromatography and HPLC, and their structures were identified by the spectal analyses and chemical evidences. RESULT: The 14 compounds were obtained and identified as neoandrographolide (1), 3, 14-di-deoxyandrographolide (2), andrographolide (3), 14-deoxy-11, 12-didehydroandrographolide (4), 19-hydroxy-8 (17), 13-labdadien-15, 16-olide (5), 14-deoxy-andrographolide (6), 3-oxo-14-deoxy-andrographolide (7), isoandrographolide, (8), bisandrographolide (9, 10, 11), deoxyandrographiside (12), 14-deoxy-11, 12-didehydroandrographiside (13), andrographiside (14), respectively. CONCLUSION: Compound 7 was a new natural product, and compound 5 was obtained for the first time from the Andrographis species.

Andrographis↗
PubMed2005

Budding dynamics of multicomponent tubular vesicles.

Real-time budding dynamics of multicomponent, tubular lipid vesicles was investigated. By using a fluorescence microscope, three typical growth modes of the buds were observed, corresponding, respectively, to bud growth through coalescence between flat patches, a bud and a patch, as well as that of two buds. The spatial and temporal scales measured in the observation were used to estimate the bending rigidity of the membrane. In the late stage, the continuing coalescence between the buds resulted in large shape deformation of the vesicles, from tubular to spherical vesicles, and the number of the buds decayed with time as N approximately t-2/3. This scaling relation was observed for the first time in experiment and confirmed early theoretical predictions. Our observation showed a difference between the diffusivity of the buds on the lipid membrane and that of the embedded membrane proteins.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2005

Aggregate morphologies of amphiphilic ABC triblock copolymer in dilute solution using self-consistent field theory.

The complex microstructures of amphiphilic ABC linear triblock copolymers in which one of the end blocks is relatively short and hydrophilic, and the other two blocks B and C are hydrophobic in a dilute solution, have been investigated by the real-space implementation of self-consistent field theory (SCFT) in two dimensions (2D). In contrast to diblock copolymers in solution, the aggregation of triblock copolymers are more complicated due to the presence of the second hydrophobic blocks and, hence, big ranges of parameter space controlling the morphology. By tailoring the hydrophobic degree and its difference between the blocks B and C, the various shapes of vesicles, circlelike and linelike micelles possibly corresponding to spherelike, and rodlike micelles in 3D, and especially, peanutlike micelles not found in diblock copolymers are observed. The transition from vesicles to circlelike micelles occurs with increasing the hydrophobicity of the blocks B and C, while the transition from circlelike micelles to linelike micelles or from the mixture of micelles and vesicles to the long linelike micelles takes place when the repulsive interaction of the end hydrophobic block C is stronger than that of the middle hydrophobic block B. Furthermore, it is favorable for dispersion of the block copolymer in the solvent into aggregates when the repulsion of the solvent to the end hydrophobic block is larger than that of the solvent to the middle hydrophobic block. Especially when the bulk block copolymers are in a weak segregation regime, the competition between the microphase separation and macrophase separation exists and the large compound micelle-like aggregates are found due to the macrophase separation with increasing the hydrophobic degree of blocks B and C, which is absent in diblock copolymer solution. The simulation results successfully reproduce the existing experimental ones.

Journal Article↗
PubMed2005

Rigid rod anchored to infinite membrane.

We investigate the shape deformation of an infinite membrane anchored by a rigid rod. The density profile of the rod is calculated by the self-consistent-field theory and the shape of the membrane is predicted by the Helfrich membrane elasticity theory [W. Helfrich, Z. Naturforsch. 28c, 693 (1973)]. It is found that the membrane bends away from the rigid rod when the interaction between the rod and the membrane is repulsive or weakly attractive (adsorption). However, the pulled height of the membrane at first increases and then decreases with the increase of the adsorption strength. Compared to a Gaussian chain with the same length, the rigid rod covers much larger area of the membrane, whereas exerts less local entropic pressure on the membrane. An evident gap is found between the membrane and the rigid rod because the membrane's curvature has to be continuous. These behaviors are compared with that of the flexible-polymer-anchored membranes studied by previous Monte Carlo simulations and theoretical analysis. It is straightforward to extend this method to more complicated and real biological systems, such as infinite membrane/multiple chains, protein inclusion, or systems with phase separation.

Adsorption↗
PubMed2005

Phase separation patterns for diblock copolymers on spherical surfaces: a finite volume method.

We explore phase separation on spherical surfaces by solving the Cahn-Hilliard equation modified for diblock copolymers using a finite volume method. The spherical surface is discretized into almost uniform triangles by employing successive dyadic refinements of the spherical icosahedron, a methodology that avoids potential mathematical and numerical problems related to the poles in spherical coordinates. The finite volume method is based on averaging Voronoi cells built from triangular meshes to calculate the Laplace-Beltrami operator on the curved surface, which greatly improves both the accuracy and speed of calculation as compared to the conventional finite difference method. By using this method we simulate the phase separation of diblock copolymers on a spherical surface. It is found that stable and intrinsic defects, which would not occur in a flat space after sufficient annealing, appear in the periodic arrangement of the domains on the curved surface due to the distinct Euler characteristic of the surface.

Journal Article↗
PubMed2005

Predicting shapes of polymer-chain-anchored fluid vesicles.

We propose a general method for predicting shapes of fluid vesicles with anchored polymers. The method combines the Helfrich curvature elasticity theory for fluid membranes and the self-consistent field theory for polymers, to determine stable and metastable shapes of the vesicles as well as the segment distributions of the anchored chains. We illustrate the method by investigating the shape change of a fluid vesicle induced by a single anchoring polymer chain. Extension to more complicated systems, such as vesicles with multiple anchored chains, block copolymers, or semiflexible chains, is straightforward.

Biopolymers↗
PubMed2005

Myofilin, a protein in the thick filaments of insect muscle.

Thick filaments in striated muscle are myosin polymers with a length and diameter that depend on the fibre type. In invertebrates, the length of the thick filaments varies widely in different muscles and additional proteins control filament assembly. Thick filaments in asynchronous insect flight muscle have an extremely regular structure, which is likely to be essential for the oscillatory contraction of these muscles. The factors controlling the assembly of thick filaments in insect flight muscle are not known. We previously identified a thick filament core protein, zeelin 1, in Lethocerus flight and non-flight muscles. This has been sequenced, and the corresponding proteins in Drosophila and Anopheles have been identified. The protein has been re-named myofilin. Zeelin 2, which is on the outside of Lethocerus flight muscle thick filaments, has been sequenced and because of the similarity to Drosophila flightin, is re-named flightin. In Drosophila flight muscle, myofilin has a molecular weight of 20 kDa and is one of five isoforms produced from a single gene. In situ hybridisation of Drosophila embryos showed that myofilin RNA is first expressed late in embryogenesis at stage 15, a little later than myosin. Antibody to myofilin labelled the entire A-band, except for the H-zone, in cryosections of flight and non-flight muscle. The periodicity of myofilin in Drosophila flight muscle thick filaments was found to be 30 nm by measuring the spacing of gold particles in labelled cryosections; this is about twice the 14.5 nm spacing of myosin molecules. The molar ratio of myofilin to myosin in indirect flight muscle is 1:2, which is the same as that of flightin. We propose a model for the association of these proteins in thick filaments, which is consistent with the periodicity and stoichiometry. Myofilin is probably needed for filament assembly in all muscles, and flightin for stability of flight muscle thick filaments in adult flies.

Alternative Splicing↗