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Biomedical subjects

Yun Liu

Publications and source records attributed to Yun Liu.

At least 55 records · Page 3Linked to original sources
PubMed2006

The TCM-combined treatment for aphasia due to cerebrovascular disorders.

OBJECTIVE: To evaluate the therapeutic effects of scalp acupuncture (with the cluster needling, a long needle-retention and an intermittent manipulation) combined with the Schuell's stimulation and psychological care for treatment of aphasia due to cerebrovascular disorders. METHOD: 36 eligible cases of aphasia were randomly assigned into a treatment group and a control group. The scoring system for assessment of aphasia in speaking Chinese set by CMA Neurological Branch and that of BADE were adopted for grading the severity/degree of aphasia before and after the treatment. RESULTS: The total effective rate in the treatment group was 84.21%, and that in the control group was 70.59%, with a very statistically significant difference (P < 0.01). CONCLUSION: The combined scheme produced a better therapeutic effect.

Acupuncture Therapy↗
PubMed2006

[Studies on chemical constituents in stem of Dendrobium chrysotoxum].

OBJECTIVE: To investigate the chemical constituents of Dendrobium chrysotoxum. METHOD: The chemical constituents were isolated by various column chromatographic methods and structurally elucidated by spectral evidences. RESULT: Ten compounds were obtained and identified as (+)-syringare sinol (1), 5alpha, 8alpha-epidioxy-24( R)-methycholesta-6, 22-dien-3beta-ol (2), trans-3-(4-hydroxy-3-methoxyphenyl)-acrylic acid octacosyl ester (3), defusin (4), 3, 4-dihydroxy benzoic acid (5), 3, 4-dimethoxy-benzoic acid (6), vanillic acid (7), 3, 4-dimethoxy-benzoic acid methyl ester (8), 3, 5-dibromo-2-aminobenzaldehyde (9), heptadecanoic acid 2, 3-dihydroxy-propyl ester (10). CONCLUSION: Compounds 1, 2 and 6-10 were isolated from this plant for the first time.

Dendrobium↗
PubMed2006

Electroanalytical method for TPPS4, the interaction of TPPS4 with BSA and the influence of CDs on it by fluorescence spectroscopy.

AIM: To establish a simple, rapid and accurate electroanalytical method for water soluble porphyrin meso-tetrakis-(4-sulfonatophenyl) porphyrin (TPPS4); to clarify the reaction between water soluble porphyrins and bovine serum albumin (BSA); and to determine the interaction of TPPS4 with BSA in the absence of presence of cyclodextrins (CDs), separately. METHODS: Three methods including LSV, UV spectroscopy and fluorescence spectroscopy had been employed to the relevant experiments. The way of employing three methods at the same time could make the experiment results more reliable. RESULTS: In the supporting electrolyte of NaH2 PO4-Na2 HPO4 (pH 7.18), a sensitive reduction peak of TPPS4 was found by linear sweep voltammetry (LSV), the peak potential (Ep) was -0.70 V (vs SCE). The relationship between the second derivative peak of LSV (ip") and the concentration of TPPS4 was linear from 1.0 x 10(-7) mol x L(-1) to 1.0 x 10(-5) mol x L(-1), the square of correlation coefficients (r2) were 0.998 3 and 0.999 3, respectively. The relative standard deviation (RSD) was 0.56% (n = 5). The mean recovery of TPPS4 was 99.59%. In NH4Cl-NH3 x H2O buffers (pH 9.05), it was proved that BSA and TPPS4 could interact with each other and form 1 : 1 TPPS4-BSA supramolecular system. Moreover, the interaction between TPPS4 and BSA had been investigated by adding cyclodextrins (CDs). The interaction of TPPS4 with BSA was facilitated both by hydroxypropyl-beta-CD (HP-beta-CD) and sulforbutylether-beta-CD (SBE-beta-CD). CONCLUSION: An electroanalytical method for TPPS4 has been established by LSV. The porphyrin drugs included by CDs could react with protein existing inside the human body easier. The consequences of this article also show that CDs will play important role in controlling and releasing the porphyrin drugs.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed2006

[Effects of exposure to extremely low frequency electromagnetic fields on reproduction of female mice and development of offsprings].

OBJECTIVE: To observe the effects of exposure to extremely low frequency electromagnetic fields (ELF EMFs) on pregnant mice and development of offsprings. METHODS: Female mice were exposed to 50 Hz, 1.2 mT electromagnetic fields during the whole pregnant period (8 h/d). The body weight of dams, delivery and development of offsprings were observed and measured. RESULTS: The increase of body weight of exposed dams (29.0%) was significantly slower than that of the control group (47.8%) during late pregnancy period (P < 0.05). The producing rate of exposed group was 60% of that of control group. Miscarriage, fetal loss and externally malformed fetus appeared in exposed group. The average number of offsprings of each exposed mouse was significantly decreased (11 +/- 1.6 vs 7 +/- 2.0, P < 0.05) and 11 for control group. Regarding the development of offspring, the body weight of prenatally exposed offsprings was increased more slowly than that of the control in the first two weeks after birth (P < 0.05). Developmental manifestations including eye opening [(252 +/- 24) h] and tooth eruption [(336 +/- 19) h] presented later in exposed offspring [(226 +/- 12), (319 +/- 15) h, respectively] (P < 0.05). CONCLUSION: Exposure to ELF EMFs during pregnancy period can cause adverse effects on pregnancy of female mice and development of offsprings.

Abnormalities, Radiation-Induced↗
PubMed2006

[Effects of ginkgolides injection on experimental cerebral ischemia in mice and rats].

OBJECTIVE: To investigate the effects of ginkgolides injection on experimental cerebral ischemia and its related mechanism of action. METHOD: The middle cerebral artery occlusion (MACO) model was induced by the FeCl3-occluding method to explore the protective effects of ginkgolides injection on the score of neurological deficits, the rate of cerebral infarction and the histomorphology of cerbral ischemia in rats. Thrombosis formation in vivo was induced by adrenaline-collagen in mice to explore the antithrombotic effect. Platelet aggregation was induced by ADP and hemorrheological parameters with hyper-viscosity by dextran T-500 were used to explore the effects of antiplatelet aggregation and decreasing viscosity of blood. RESULT: Ginkgolides injection could markedly decrease the infarct size and behavior deficits score, inhibit the thrombus formation in mice, decrease blood viscosity and ameliorate hemorrheological parameters in rat. CONCLUSION: Ginkgolides injection has the protective effects on focal cerebral ischemia, and its mechanism may be relative to its inhibition of platelet-dependent thrombosis and amelioration of hemarheological partments.

Animals↗
PubMed2005

Effects of counterion valency on the damping of phonons propagating along the axial direction of liquid-crystalline DNA.

The phonon propagation and damping along the axial direction of films of aligned 40 wt % calf-thymus DNA rods are studied by inelastic x-ray scattering (IXS). The IXS spectra are analyzed with the generalized three effective eigenmode theory, from which we extract the dynamic structure factor S(Q,E) as a function of transferred energy E=variant Planck's over 2piomega, and the magnitude of the transferred wave vector Q. S(Q,E) of a DNA sample typically consists of three peaks, one central Rayleigh scattering peak, and two symmetric Stokes and anti-Stokes Brillouin side peaks. By analyzing the Brillouin peaks, the phonon excitation energy and damping can be extracted at different Q values from about 4 to 30 nm(-1). A high-frequency sound speed is obtained from the initial slope of the linear portion of the dispersion relation below Q=4 nm(-1). The high-frequency sound speed obtained in this Q range is 3100 ms, which is about twice faster than the ultrasound speed of 1800 ms, measured by Brillouin light scattering at Q approximately 0.01 nm(-1) at the similar hydration level. Our observations provide further evidence of the strong coupling between the internal dynamics of a DNA molecule and the dynamics of the solvent. The effect on damping and propagation of phonons along the axial direction of DNA rods due to divalent and trivalent counterions has been studied. It is found that the added multivalent counterions introduce stronger phonon damping. The phonons at the range between approximately 12.5 and approximately 22.5 nm(-1) are overdamped by the added counterions according to our model analyses. The intermediate scattering function is extracted and it shows a clear two-step relaxation with the fast relaxation time ranging from 0.1 to 4 ps.

DNA↗
PubMed2005

Evidence for recombination of mitochondrial DNA in triploid crucian carp.

In this study, we report the complete mitochondrial DNA (mtDNA) sequences of the allotetraploid and triploid crucian carp and compare the complete mtDNA sequences between the triploid crucian carp and its female parent Japanese crucian carp and between the triploid crucian carp and its male parent allotetraploid. Our results indicate that the complete mtDNA nucleotide identity (98%) between the triploid crucian carp and its male parent allotetraploid was higher than that (93%) between the triploid crucian carp and its female parent Japanese crucian carp. Moreover, the presence of a pattern of identity and difference at synonymous sites of mitochondrial genomes between the triploid crucian carp and its parents provides direct evidence that triploid crucian carp possessed the recombination mtDNA fragment (12,759 bp) derived from the paternal fish. These results suggest that mtDNA recombination was derived from the fusion of the maternal and paternal mtDNAs. Compared with the haploid egg with one set of genome from the Japanese crucian carp, the diploid sperm with two sets of genomes from the allotetraploid could more easily make its mtDNA fuse with the mtDNA of the haploid egg. In addition, the triple hybrid nature of the triploid crucian carp probably allowed its better mtDNA recombination. In summary, our results provide the first evidence of mtDNA combination in polyploid fish.

Animals↗
PubMed2005

Density functional study of the in-line mechanism of methanolysis of cyclic phosphate and thiophosphate esters in solution: insight into thio effects in RNA transesterification.

Density functional calculations of thio effects on the in-line mechanism of methanolysis of ethylene phosphate (a reverse reaction model for RNA phosphate transesterification) are presented. A total of 12 reaction mechanisms are examined using the B3LYP functional with large basis sets, and the effects of solvation were treated using the PCM, CPCM, and SM5 solvation models. Single thio substitutions at all of the distinct phosphoryl oxygen positions (2', 3', 5', pro-R) and a double thio substitution at the nonbridging (pro-R/pro-S) positions were considered. Profiles for each reaction were calculated in the dianionic and monoanionic/monoprotic states, corresponding to reaction models under alkaline and nonalkaline conditions, respectively. These models provide insight into the mechanisms of RNA transesterification thio effects and serve as a set of high-level quantum data that can be used in the design of new semiempirical quantum models for hybrid quantum mechanical/molecular mechanical simulations and linear-scaling electronic structure calculations.

Cyclization↗
PubMed2005

Bamboo-shaped Ag-doped TiO2 nanowires with heterojunctions.

Bamboo-shaped Ag-doped TiO2 nanowires with heterojunctions were synthesized by a simple solvothermal method. The diameter of the nanowires was about 50-100 nm, and they had a length of up to a few millimeters. The detailed structure of the heterojunction in the nanowire was also characterized.

Journal Article↗
PubMed2005

Analysis of expressed sequence tags from the venom ducts of Conus striatus: focusing on the expression profile of conotoxins.

Cone snails (genus Conus) are predatory marine gastropods that use venom peptides for interacting with prey, predators and competitors. A majority of these peptides, generally known as conotoxins demonstrate striking selectivity in targeting specific subtypes of ion channels and neurotransmitter receptors. So they are not only useful tools in neuroscience to characterize receptors and receptor subtypes, but offer great potential in new drug research and development as well. Here, a cDNA library from the venom ducts of a fish-hunting cone snail species, Conus striatus is described for the generation of expressed sequence tags (ESTs). A total of 429 ESTs were grouped into 137 clusters or singletons. Among these sequences, 221 were toxin sequences, accounting for 52.1% (corresponding to 19 clusters) of all transcripts. A-superfamily (132 ESTs) and O-superfamily conotoxins (80 ESTs) constitute the predominant toxin components. Some non-disulfide-rich Conus peptides were also found. The expression profile of conotoxins also explained to some extent the pharmacological and physiological reactions elicited by this typical piscivorous species. For the first time, a nonstop transcript of conotoxin was identified, which is suggestive that alternative polyadenylation may be a means of post-transcriptional regulation of conotoxin production. A comparison analysis of these conotoxins reveals the different variation and divergence patterns in these two superfamilies. Our investigations indicate that focal hyper-mutation, block substitution and exon shuffling are three main mechanisms leading to the conotoxin diversity in a species. The comprehensive set of Conus gene sequences allowed the identification of the representative classes of conotoxins and related components, which may lay the foundation for further research and development of conotoxins.

Amino Acid Sequence↗
PubMed2005

Effective long-range attraction between protein molecules in solutions studied by small angle neutron scattering.

Small angle neutron scattering intensity distributions taken from cytochrome C and lysozyme protein solutions show a rising intensity at a very small wave vector Q, which can be interpreted in terms of the presence of a weak long-range attraction between protein molecules. This interaction has a range several times that of the diameter of the protein molecule, much greater than the range of the screened electrostatic repulsion. We show evidence that this long-range attraction is closely related to the type of anion present and ion concentration in the solution.

Animals↗
PubMed2005

Theoretical studies of dissociative phosphoryl transfer in interconversion of phosphoenolpyruvate to phosphonopyruvate: solvent effects, thio effects, and implications for enzymatic reactions.

The conversion of phosphoenolpyruvate (PEP) to phosphonopyruvate (P-pyr) is catalyzed by PEP mutase via a dissociative mechanism. In this work, we investigate the uncatalyzed reaction using ab initio methods, density functional theory, and the semiempirical MNDO/d method. Comparisons of geometries and relative energies of stationary points (minima and transition states) with density functional results indicate that the semiempirical method is reasonably accurate. Solvent effects are examined using implicit solvent models, including the recently extended smooth conductor-like screening model. Due to the large negative charge carried by the system, solvation is found to drastically alter the location and energy of stationary points along the dissociative reaction pathways. The influence of substituting a nonbridging phosphoryl oxygen by sulfur (thio effects) was also investigated. Implications of these results for the enzymatic reaction are discussed.

Calibration↗
PubMed2005

Potential new antitumor agents from an innovative combination of camphorato, a ramification of traditional Chinese medicine, with a platinum moiety.

Eight new camphorato platinum complexes have been synthesized and evaluated for their in vitro cytotoxicity against HL-60 human leukemia, 3AO human ovarian carcinoma, BEL-7402 human hepatocarcinoma, and A549 human lung carcinoma cell lines. Most complexes showed good cytotoxic activity against the above-selected cell lines. Among the complexes, two compounds were assayed for their in vivo antitumor activity against LS-174T human colon carcinoma cells implanted in mice. One complex exhibited not only higher in vivo antitumor activity, but also less toxicity than oxaliplatin when it was administered intravenously at a dose of 6 mg/kg three times.

Animals↗
PubMed2005

Neuregulin-1 increases the proliferation of neuronal progenitors from embryonic neural stem cells.

Neuregulins are a family of proteins expressed in the developing brain and in brain regions that continue to undergo neurogenesis in adult animals. We investigated the effects of neuregulins on embryonic neural stem cells (NSCs) isolated from E11 mouse telencephalon. Treatment of basic fibroblast growth factor (bFGF)-expanded neurosphere cultures with the EGF-like domain of neuregulin1-beta1 (NRG-1(177-244)) resulted in a 4-fold increase of bromodeoxyuridine (BrDU)-labeled cells, suggesting that NRG-1 stimulated proliferation. The majority of the BrdU-positive cells co-labeled with an antibody against MAP2, indicating that the proliferating cells were neuronal. No BrDU labeling was seen in GFAP- or O4-positive cells. In NRG-1-treated cultures, many of the MAP2-positive cells co-labeled with an anti-nestin antibody, suggesting that these cells are neuron-restricted progenitors (NRPs). Few MAP2/nestin-positive cells were seen in control cultures. The increase in the number of neuronal cells in NRG-1-treated cultures was due to increased proliferation of MAP2-positive cells rather than the regulation of cell survival or fate determination. These results suggest that neuregulins are mitogenic to NRPs, thus endogenous neuregulins may play important roles during CNS neurogenesis.

Animals↗
PubMed2005

Depositional characteristics of metal coating on single-crystal TiO2 nanowires.

Ultralong single-crystalline TiO(2) nanowires were prepared by a simple, low-cost solvothermal process. Silver nitrate, neodymium chloride, ceric nitrate, stannic chloride hydrate, and cadmium chloride were used as metal sources and deposited by reduction on the surface of TiO(2) nanowires. The composites were subsequently characterized by transmission electron microscopy, and their coverage was compared. The nature of the coatings on the TiO(2) nanowires varies from metal to metal. A novel approach on modified one-dimensional nanostructures with metal coating was developed, which has great potential applications in catalysts, sensors, and nanoscale devices.

Journal Article↗
PubMed2005

Opposing effects of bovine papillomavirus type 1 E6 and E7 genes on Fas-mediated apoptosis.

Programmed cell death (PCD), best exemplified by apoptosis, is a genetically programmed process of cellular destruction that is indispensable for normal development and homeostasis of multicellular organisms. Tumor necrosis factor alpha (TNF) and related cytokines are employed by host defenses to eliminate virally infected cells through induction of apoptosis. Many viruses have evolved specific gene products to modulate this process. We have recently shown that the bovine papillomavirus type 1 (BPV-1) E6 and E7 genes independently sensitize mouse cells to TNF-induced apoptosis. In this report, we investigated the effect of E6 and E7 expression on Fas-mediated apoptosis. In contrast to TNF-mediated apoptosis, E6 and E7 demonstrated opposite effects: while E7 potentiated apoptosis triggered by an agonistic Fas antibody, E6 attenuated the effect. The mitochondrial pathway leading to the activation of caspases appears to be involved in Fas-mediated apoptosis in C127 cells. To further explore the mechanisms by which E6 and E7 modulate Fas-mediated apoptosis, we examined the surface expression of Fas in cells expressing E6 and E7. Significantly, levels of surface Fas expression correlated with the opposing effects of E6 and E7 on Fas-mediated apoptosis. Specifically, while E7 increased the surface expression of Fas, E6 reduced surface Fas expression. Mutational analysis demonstrated a correlation of E6's ability to downregulate surface Fas expression and apoptosis. Since the tumor suppressor p53 can be targeted for degradation by human papillomavirus and has been shown to induce apoptosis by upregulating surface Fas expression, we investigated the role of p53 in BPV-1 E6 and E7 modulation of Fas-mediated apoptosis. Our results demonstrated that the modulatory effects by E6 and E7 could occur in the absence of p53. Interestingly, the reduced Fas protein level on the cell surface is not accompanied by a decrease in total Fas levels in E6-expressing cells. Instead, considerably more Fas protein is found in the cytoplasm of cells expressing E6. These results highlight a novel activity of E6 and E7 that may be involved in viral pathogenesis.

Animals↗
PubMed2005

PM2, a group 3 LEA protein from soybean, and its 22-mer repeating region confer salt tolerance in Escherichia coli.

To have knowledge of the effect of soybean PM2 protein in protecting dehydrated cells and its functional region, PM2 cDNA was isolated from soybean immature seeds. The recombinants expressing full-length PM2, truncated polypeptides of PM2A (aa 1-262) or PM2B (aa 129-262, 22-mer repeating region), or artificial polypeptide PM2C (duplication of 22-mer repeating region) were constructed. By using SDS-PAGE and mass spectrometry approaches, these fusion polypeptides were identified and proved to be hydrophilic and heat-stable. Spot assays of BL/PM2 and BL/pET28 (as control) showed that protein PM2 increased salt tolerance (500 mM NaCl or 500 mM KCl) of Escherichia coli, rather than osmotic tolerance (1100 mM sorbitol). In addition, comparing the survival ratios of the transformants under 500 mM NaCl or 500 mM KCl stresses, the results showed that: (1) the survival ratios of BL/PM2 and BL/PM2B were quite similar, both showing much higher values than those of BL/pET28. (2) The survival ratios of BL/PM2C were much higher than those of BL/PM2, BL/PM2A, and BL/PM2B. This provides the first experimental evidence that PM2 polypeptide enhances salt tolerance of E. coli cells, and the 22-mer repeat region is an important functional region.

Electrophoresis, Polyacrylamide Gel↗