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Biomedical subjects

Y Xie

Publications and source records attributed to Y Xie.

At least 145 records · Page 8Linked to original sources
PubMed2001

[Clinical evaluation on second stage reconstruction for laryngostenosis after partial laryngectomy for laryngeal cancer patients].

OBJECTIVE: To present a new method of decannulation for laryngostenosis patients after partial laryngectomy and extended partial laryngectomy, and restoration of the essential functions of larynx and normal neck appearance. METHODS: Nineteen cases of laryngostenosis after partial laryngectomy and extended partial laryngectomy were treated with second stage reconstruction. The patients had been treated by vertical laryngectomy (6/19) using extended vertical laryngectomy (11/19) and frontolateral laryngectomy (2/19). Among these patients, second stage reconstruction of larynx was performed by using rotary door myocutaneous flap (17/19). Stemohyoideus flap (1/19) and sternocleidomastoid flap (1/19). RESULTS: Three and five year-survival rates were 91.7% (11/12) and 3/5, respectively. Over-all decannulation rate was 84.2% (16/19), but 94.1% (16/17) in patients with rotary door myocutaneous flap and 0% (0/2) in both patients with sternohyoideus flap and sternocleidomastoid flap. There were 3 decannulation failures (15.8%). All patients resumed acceptable voice, 94.7% (18/19) enjoyed satisfactory phonation, but 5.3% (1/19) showed severe hoarseness. All except 2 patients returned normal swallow function. The latter 2 patients experienced mild abnormal swallow during eating fluid food in early stage of surgery, but had normal swallow function after 1-2 weeks. CONCLUSION: Functional laryngectomy is a radical operation in selected cases with advanced laryngeal cancer. The second stage reconstruction with bi-pedical rotary door myocutaneous flaps can help decannulation in patients who developed laryngostenosis after partial laryngectomy and extended partial laryngectomy, and restore the essential function of larynx and normal neck appearance.

Adult↗
PubMed2001

[Expression of matrix metalloproteinasa-2,9 in cholesteatoma and middle ear cancer].

OBJECTIVE: To study various expressions and roles of MMP-2, 9 in cholesteatoma and middle ear cancer. METHODS: MMP-2 and MMP-9 were detected with immunohistochemical methods using monoclonal antibody in 36 cholesteatomas, 10 CAMS and 16 middle ear cancer. RESULTS: The stain in cholesteatoma was stronger than that in CAMS and NAMS. Expressions of MMP-2, 9 were seen in all layers of the epithelium in CA and the stain was strongest in basement membrane. The positive rates of stain was 83% and 50% in CA and CAMS respectively. There was weak stain in 2 NAMS. In middle ear cancer, the expression rates of MMP-9 and MMP-2 were 50% (8/16) and 56.25% (9/16) respectively. The expression level was correlated with tumor differentiation and its clinical stage. Expressions of MMP-2 and MMP-9 were closely related in cholesteatoma. There was no relationship between expressions of MMP-2 and MMP-9 in middle ear cancer. CONCLUSION: Cholesteatoma has a similar feature with middle ear cancer in invading surrounding of surround bone matrix. The disorder between MMPs and its inhibitor was one of reasons for bone absorption of cholesteatoma and middle ear cancer.

Adolescent↗
PubMed2001

[HPLC determination of oleanolic acid and llrolic acid in Chinese medicinal herbs].

OBJECTIVE: To develop a new method for simultaneous determination of oleanolic acid and llrolic acid in Chinese medicinal herbs at the same time. METHOD: HPLC was carried out on a Shim-pack CLC-ODS column using MeOH-H2O-HOAc-TEA (83:17:0.04:0.02). RESULT AND CONCLUSION: The average recovery of oleanolic acid and llrolic acid was 103.3 +/- 2.07% and 102.7% +/- 0.65% respectively.

Chromatography, High Pressure Liquid↗
PubMed2000

TATA-binding protein and the Gal4 transactivator do not bind to promoters cooperatively.

The yeast Gal4 protein, like many activators, binds TATA-binding protein (TBP) directly in vitro. It has been speculated that this protein-protein interaction is important for Gal4p-mediated activation of transcription, but little work has been done to test specific models involving this interaction. In this study, the effect of Gal4p on TBP-TATA binding is addressed. Specifically, it is asked if the Gal4p-TBP interaction can support cooperative binding of the two factors to promoters. It is easy to see how such an event could stimulate transcription, particularly from promoters with a non-consensus TATA box. In vitro, however, a derivative of Gal4p (Gal4-(1-93+768-881)) containing the DNA-binding, dimerization, and activation domains does not bind to promoter DNA cooperatively with either recombinant, purified TBP, or with protein from a yeast crude extract. In vivo, reporter gene experiments using promoters with differing TBP affinities reveal no major Gal4p-mediated stimulation of TBP function from weak TATA boxes, as would be predicted if the proteins bind cooperatively. Furthermore, native Gal4p and a potent Gal4p-based artificial activator lacking a TBP-binding activation domain support similar ratios of transcription from a series of promoters identical except for mutations in the TATA box. It is concluded that Gal4p and TBP do not bind cooperatively to promoters and that this mechanism does not contribute substantially to Gal4p-mediated transcriptional activation.

DNA↗
PubMed2000

Plasmids encoding foot-and-mouth disease virus VP1 epitopes elicited immune responses in mice and swine and protected swine against viral infection.

VP1 is a capsid protein of foot-and-mouth disease virus (FMDV) and contains epitopes of the virus. Plasmids encoding two VP1 epitopes (amino acid residues 141-160 and 200-213) and a host-self immunoglobulin molecule were constructed to produce a new type of FMD DNA vaccine. Two plasmids, namely, pCEIM and pCEIS, containing mouse immunoglobulin (IgG) or swine IgG were subjected to immunogenicity testing in mice and swine, respectively. In mice administrated pCEIM in the abdomen using a genegun, both FMDV-specific T-cell proliferation and neutralizing antibodies were detected. In swine immunized with pCEIS at the back of the ear, immune responses were achieved after the second administration. Swine showed a T-cell proliferative response with a stimulation index (SI) of up to 8.1 and a neutralizing antibody response that was able to protect suckling mice from 10(2) LD(50) (lethal dose 50) FMDV challenge. To compare the immunogenicity of the DNA-based vaccine candidate, versus the protein-based vaccine candidates, a second group of swine was immunized with the protein F1-scIgG, which was encoded by the plasmid pCEIS. Injection with F1-scIgG elicited a T-cell proliferative response of SI < 1.7 and a neutralizing antibody response that protected suckling mice from up to 10(5) LD(50) FMDV challenge. In the challenge test, three of three swine immunized with pCEIS were fully protected from FMDV challenge.

Animals↗
PubMed2000

Contributions of Torpedo nicotinic acetylcholine receptor gamma Trp-55 and delta Trp-57 to agonist and competitive antagonist function.

Results of affinity-labeling studies and mutational analyses provide evidence that the agonist binding sites of the nicotinic acetylcholine receptor (nAChR) are located at the alpha-gamma and alpha-delta subunit interfaces. For Torpedo nAChR, photoaffinity-labeling studies with the competitive antagonist d-[(3)H]tubocurarine (dTC) identified two tryptophans, gammaTrp-55 and deltaTrp-57, as the primary sites of photolabeling in the non-alpha subunits. To characterize the importance of gammaTrp-55 and deltaTrp-57 to the interactions of agonists and antagonists, Torpedo nAChRs were expressed in Xenopus oocytes, and equilibrium binding assays and electrophysiological recordings were used to examine the functional consequences when either or both tryptophans were mutated to leucine. Neither substitution altered the equilibrium binding of dTC. However, the deltaW57L and gammaW55L mutations decreased acetylcholine (ACh) binding affinity by 20- and 7,000-fold respectively. For the wild-type, gammaW55L, and deltaW57L nAChRs, the concentration dependence of channel activation was characterized by Hill coefficients of 1.8, 1.1, and 1.7. For the gammaW55L mutant, dTC binding at the alpha-gamma site acts not as a competitive antagonist but as a coactivator or partial agonist. These results establish that interactions with gamma Trp-55 of the Torpedo nAChR play a crucial role in agonist binding and in the agonist-induced conformational changes that lead to channel opening.

Acetylcholine↗
PubMed2000

An immunoglobulin G based chimeric protein induced foot-and-mouth disease specific immune response in swine.

Epitopes containing the residues 141aa-160aa and 200aa-213aa from foot-and-mouth disease (FMD) serotype O1K HK type FMDV VP1 were joined to a swine immunoglobulin G single heavy chain constant region (scIgG), creating a novel chimeric protein, named F1-scIgG. In this study, inoculation with F1-scIgG induced both FMD virus-neutralizing antibody response and T cell response in swine. Antisera from these F1-scIgG-inoculated swine protected suckling mice against 1000 lethal dose 50 (1000LD(50)) FMD challenge. F1-scIgG-inoculated swine were also fully protected against 50LD(50) FMD virus challenge. The present study demonstrates the clear potential for viral epitopes linked with self-Ig in novel FMD vaccine design.

Animals↗
PubMed2000

Biochemical characterization of the TATA-binding protein-Gal4 activation domain complex.

It has been suggested that complexes between gene-specific activators and the TATA-binding protein (TBP) play an important role in the expression of many genes. However, few detailed studies of well defined activator-TBP complexes have been reported. An analysis of the biochemical properties of the complex formed by the acidic activation domain (AAD) of the yeast activator Gal4 and TBP is presented here. This is shown to be composed of two AAD and one TBP molecule. DNA binding experiments reveal that TATA-containing DNAs and the Gal4 AAD bind TBP competitively, suggesting that the AAD and TATA boxes recognize overlapping surfaces of TBP. The kinetics of the formation and dissociation of the AAD(2)-TBP complex is also probed. The impact of these findings on models for Gal4-mediated transcriptional activation is considered.

Binding, Competitive↗
PubMed2000

Nerve growth factor (NGF) loop 4 dimeric mimetics activate ERK and AKT and promote NGF-like neurotrophic effects.

Previous work indicating that nerve growth factor (NGF) protein loops 2 and 4 interact with TrkA receptors raise the possibility that small molecule mimetics corresponding to TrkA-interacting domains that have NGF agonist activity can be developed. We applied our previously developed strategy of dimeric peptidomimetics to address the hypothesis that loop 4 small molecule dimeric mimetics would activate TrkA-related signal transduction and mimic NGF neurotrophic effects in a structure-specific manner. A loop 4 cyclized peptide dimer demonstrated NGF-like neurotrophic activity, whereas peptides with scrambled sequence, added or substituted residues, or cyclized in monomeric form were inactive. Activity was blocked by the TrkA inhibitors K252a and AG879 but not by NGF p75 receptor blocking antibody. Dimeric, but not monomeric, peptides partially blocked NGF activity. This profile was consistent with that of a NGF partial agonist. ERK and AKT phosphorylation was stimulated only by biologically active peptides and was blocked by K252a. The ERK inhibitor U0126 blocked the neurite- but not the survival-promoting activity of both NGF and active peptide. These studies support the proof of concept that small molecule NGF loop 4 mimetics can activate NGF signaling pathways and can mimic death-preventing and neurite-promoting effects of NGF. This finding will guide the rational design of NGF single-domain mimetics and contribute to elucidating NGF signal transduction mechanisms.

Animals↗
PubMed2000

Probing the structure of the nicotinic acetylcholine receptor with 4-benzoylbenzoylcholine, a novel photoaffinity competitive antagonist.

[(3)H]4-Benzoylbenzoylcholine (Bz(2)choline) was synthesized as a photoaffinity probe for the Torpedo nicotinic acetylcholine receptor (nAChR). [(3)H]Bz(2)choline acts as an nAChR competitive antagonist and binds at equilibrium with the same affinity (K(D) = 1.4 microm) to both agonist sites. Irradiation at 320 nm of nAChR-rich membranes equilibrated with [(3)H]Bz(2)choline results in the covalent incorporation of [(3)H]Bz(2)choline into the nAChR gamma- and delta-subunits that is inhibitable by agonist, with little specific incorporation in the alpha-subunits. To identify the sites of photoincorporation, gamma- and delta-subunits, isolated from nAChR-rich membranes photolabeled with [(3)H]Bz(2)choline, were digested enzymatically, and the labeled fragments were isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and/or reversed-phase high performance liquid chromatography. For the gamma-subunit, Staphylococcus aureus V8 protease produced a specifically labeled peptide beginning at gammaVal-102, whereas for the delta-subunit, endoproteinase Asp-N produced a labeled peptide beginning at deltaAsp-99. Amino-terminal sequence analysis identified the homologous residues gammaLeu-109 and deltaLeu-111 as the primary sites of [(3)H]Bz(2)choline photoincorporation. This is the first identification by affinity labeling of non-reactive amino acids within the acetylcholine-binding sites, and these results establish that when choline esters of benzoic acid are bound to the nAChR agonist sites, the para substituent is selectively oriented toward and in proximity to amino acids gammaLeu-109/deltaLeu-111.

Benzoylcholine↗
PubMed2000

Increased expression of insulin-like growth factor I receptor in malignant cells expressing aberrant p53: functional impact.

We investigated the functional impact of p53 on insulin-like growth factor I receptor (IGF-IR) expression in malignant cells. Using the BL-41tsp53-2 cell line, a transfectant carrying temperature-sensitive (ts) p53 and endogenous mutant p53 (codon 248), we demonstrated a drastic down-regulation of plasma membrane-bound IGF-IRs on induction of wild-type p53. However, a similar response was obtained by treatment of BL-41tsp53-2 cells expressing mutant ts p53 with a p53 antisense oligonucleotide. Thus, even if the negative effect of wild-type p53 predominates under a competitive condition, these data indicate that mutant p53 may be important for up-regulation of IGF-IR. To further elucidate this issue, three melanoma cell lines (BE, SK-MEL-5, and SK-MEL-28) that overexpressed p53 were investigated. The BE cell line has a "hot spot" mutation (codon 248) and expresses only codon 248-mutant p53. SK-MEL-28 has a point mutation at codon 145. SK-MEL-5 cells did not exhibit any p53 mutations, but the absence of p21Waf1 expression suggested functionally aberrant p53. Our data suggest that interaction with Mdm-2 may underlie p53 inactivation in these cells. Using p53 antisense oligonucleotides, we demonstrated a substantial down-regulation of cell surface expression of IGF-IR proteins in all melanoma cell lines after 24 h. This was paralleled by decreased tyrosine phosphorylation of IGF-IR and growth arrest, and, subsequently, massive cell death was observed (this was also seen in BL-41tsp53-2 cells with mutant conformation of ts p53). Taken together, our results suggest that up-regulation of IGF-IR as a result of expression of aberrant p53 may be important for the growth and survival of malignant cells.

Acetylcysteine↗
PubMed2000

Templated Synthesis of CdS/PAN Composite Nanowires under Ambient Conditions.

CdS/PAN (polyacrylonitrile) composite nanowires were prepared by templated synthesis under ambient conditions, using a 4 : 1 (v/v) distilled water-isopropyl alcohol solvent mixture and Na(2)S(2)O(3) as sulfur source. Transmission electron microscopy images showed typical CdS/PAN nanowires with diameters less than 6 nm and lengths from 200 nm to 1 µm. CdS/PAN nanowires were also characterized by FT-infrared spectra (FTIR), X-ray powder diffraction (XRD) patterns, and UV-vis spectra. It is found that the feed mole ratio of CdCl(2) to AN exerts a significant influence on the formation and morphology of CdS/PAN nanowires. In addition, possible mechanism of the reactive process was presented. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Crystal structure of recombinant trypsin-solubilized fragment of cytochrome b(5) and the structural comparison with Val61His mutant.

The crystal structure of the recombinant trypsin-solubilized fragment of the microsomal cytochrome b(5) from bovine liver has been determined at 1.9 A resolution and compared with the reported crystal structure of the lipase-solubilized fragment of the membrane protein cytochrome b(5). The two structures are similar to each other. However, some detailed structural differences are observed: the conformation of the segment Asn16-Ser20 is quite different, some helices around the heme and some segments between the helices are shifted slightly, the heme is rotated about the normal of the mean plane of heme, one of the propionates of the heme exhibits a different conformation. The average coordination distances between the iron and the two nitrogen atoms of the imidazole ligands are the same in the two structures. Most of the structural differences can be attributed to the different intermolecular interactions which result from the crystal packing. The wild-type protein structure is also compared with its Val61His mutant, showing that the heme binding and the main chain conformations are basically identical with each other except for the local area of the mutation site. However, when Val61 is mutated to histidine, the large side chain of His61 is forced to point away from the heme pocket toward the solvent region, disturbing the micro-environment of the heme pocket and influencing the stability and the redox potential of the protein.

Animals↗
PubMed2000

Solvothermal route to tin monoselenide bulk single crystal with different morphologies.

Orthorhombic SnSe bulk single crystals with different morphologies were conveniently grown through solvothermal process at low temperature (180 degrees C). X-ray diffraction (XRD) patterns, scanning electronic microscope (SEM) images, electronic diffraction (ED), and X-ray photoelectron spectra (XPS) were used to characterize the products. In the solvothermal process, the solvent plays an important role in the growth of the single crystal. The morphology of the crystal is influenced not only by the kind of solvent but also by the concentration of the reactants in solvent. Single crystals with rodlike or platelike morphology can be conveniently obtained under controlled concentration of reactants in solvent.

Journal Article↗
PubMed2000

Catalyzed hydrolysis of nerve gases by metal chelate compounds and potentiometric detection of the byproducts.

A new method for detection of nerve gases, Sarin and Soman, was proposed on the basis of their catalyzed hydrolysis by metal chelate compounds and potentiometric detection of the byproduct, fluoride ion. Diisopropyl fluorophosphate (DFP) was used as a nerve gas mimic. The copper ion chelates shift the potential of the fluoride ion-selective electrode to more positive stable potential, which is beneficial for lowering the detection limit. In the presence of DFP, the electrode potential decreases rapidly with time due to the catalyzed hydrolysis of DFP and the production of fluoride ion. This method is sensitive, selective, and reproducible. The detection limit for DFP is 2 x 10(-6) M with a potential drop between 40 and 60 mV.

Catalysis↗