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Biomedical subjects

Y Deng

Publications and source records attributed to Y Deng.

At least 145 records · Page 8Linked to original sources
PubMed1998

[Microvasculature of the dog's periodontal ligament and its immediate response to orthodontic forces].

The purpose of this study was to examine the microvascular architecture of dog's periodontal ligament (PDL) and its immediate response to horizontal orthodontic force. A force of 200 g was applied mesially to the mandibular premolar of a dog for 2 hours, the distal side served as the contrast side. Formalin ink was perfused into the carotid arteries bilaterally through the cannulas. After perfusion the mandible was decalcified, celloidin embedded, serially sectioned and stained with eosin. The sections were then observed by light microscope and analyzed by image analyzer. Vascular corrosion casts were prepared by the similar way with the formalin ink perfusion and examined by scanning electron microscope. The results showed: there were extensive interconnections among the PDL, dental pulp, gingiva, alveolus and the neighbour tooth PDL, which would benefit the maintenance of health and functions of the dental pulp and the periodontal tissues. Arterioles and venulae could be confirmed by the presence of characteristic differences of nuclear impressions in endothelial cell under the scanning electron microscope. The quantitative analysis showed that the tensioned PDL sites in the experimental group had a higher microvascular volume density than the corresponding sites in the contrast group, while the pressed PDL sites in the experimental group had a lower microvascular volume density than the corresponding sites in the contrast group. This should result from the hydraulic mechanism in the PDL.

Animals↗
PubMed1998

[The composition and distribution of some kinds of anaerobic microorganisms in Yinqion basin].

Under the strictly anaerobic conditions, the population of Sulfate-reducing bacteria, fermentative bacteria and methanogenic bacteria of serial samples got from erect sections of different Sedimentary of Yingqiong basin (a typical marine sedimentary environment) were measured by MPN method. The morphology of different kinds of bacteria and the metabolic types of methanogen and methanogenic activity were observed. The relation between population of bacteria and some indexes were compared. The results show that SRB present in all of the samples. The distribution of SRB and fermentative bacteria have no interrelation with the depth of samples but SRB has interrelation with the SO(4)2- concentration, and fermentative bacteria has negative interrelation with the contents of organic matter. Two kinds of methanogen present in all of the samples. They belong to Methanobacterium and Methanococcus, respectively. Their types of nutriment are H2/CO2.

Bacteria, Anaerobic↗
PubMed1998

[The influence of basic fibroblast growth factor on the adherence of endothelial cell to polyurethane].

This study addressed the problem of how to promote the adherence of endothelial cells (EC) to polyurethane (PU). The influence of basic fibroblast growth factor (bFGF) on the adherence of EC to PU was observed by using the fluorescent method. The results showed that the attachment rates for two bFGF groups(PU precoated with fibronectin and PU precoated with collagen IV) were 71% and 68.5%, which were significantly higher than those (62.5% and 55.25%) for two control groups, respectively. These demonstrate that bFGF can promote EC attachment to PU, and suggest that bFGF can be used as a supplement factor in media for achievement of endothelialization on artificial heart and blood vessels.

Animals↗
PubMed1998

[Studies on target localization of Parkinson's disease treated with gamma knife].

Ninety cases of Parkinson's disease were treated in our center from Dec. 1993 to Aug. 1997. Based on our work, we have developed a method for the MR localization in the treatment of Parkinson's disease with Gamma knife, including the fixing of stereotactic frame, the selection of target, and the correction of the target's coordinates. In this paper, the effects of fixing of coordinate frame on the localization of target have been analyzed. Also presented are the errors of the coordinates of the selected targets, compared with those corrected. The method reflects a new idea for target localization.

Algorithms↗
PubMed1997

Preparation of (R)-N-methylsalsolinol via reversed-phase high-performance liquid chromatography using beta-cyclodextrin as a mobile-phase additive.

A new preparation method was devised using beta-cyclodextrin as a mobile-phase additive in a reversed-phase high-performance liquid chromatography system. Preparative separation of the biologically active (R)-enantiomer was achieved from racemic N-methylsalsolinol. Beta-cyclodextrin was removed completely in good yield by acid extraction and solid-phase extraction. By a slight modification, this method will be applicable to the isolation of various types of biologically important enantiomers.

Chromatography, High Pressure Liquid↗
PubMed1997

Electrochemical behavior of [ReI(DMPE)3]+, where DMPE = 1,2-bis(dimethylphosphino)ethane, at perfluorosulfonated ionomer-modified electrodes.

The perfluorosulfonated ionomer Nafion shows potential utility as a polymer film to enhance the electrochemical detection of [ReI(DMPE)3]+, where DMPE = 1,2-bis-(dimethylphosphino)ethane. [ReI(DMPE)3]+, a nonradioactive radiopharmaceutical analog for heart imaging, partitions strongly into Nafion films on glassy carbon. Well-defined, chemically reversible cyclic voltammograms are obtained for the [ReI(DMPE)3]+/[ReII(DMPE)3]2+ couple with Eo' shifted positively by 60 mV relative to its value on bare glassy carbon. [ReI(DMPE)3]+ partitions into Nafion more strongly than the oxidized form, [ReII-(DMPE)3]2+. The detection limit for [ReI(DMPE)3]+ by cyclic voltammetry was improved by 2-3 orders of magnitude by the Nafion film. Differential pulse voltammetry for oxidation of [ReI(DMPE)3]+ at the Nafion-modified electrode has a detection limit of 2.5 x 10(-9) M compared to 1.0 x 10(-7) M at the bare electrode. A preconcentration factor of 1 x 10(6) for partitioning of [ReI(DMPE)3]+ from 0.05 M NaCl into Nafion on a glassy carbon electrode was measured.

Electrochemistry↗
PubMed1997

Assay for the (R)- and (S)-enantiomers of salsolinols in biological samples and foods with ion-pair high-performance liquid chromatography using beta-cyclodextrin as a chiral mobile phase additive.

A chromatographic procedure was devised for the quantitative determination of the enantiomers of salsolinol and N-methylsalsolinol, which are biologically important alkaloids. The enantiomers of salsolinol and N-methylsalsolinol were completely separated using beta-cyclodextrin in a reversed-phase ion-pair system. The HPLC method was sensitive enough to detect the isoquinolines at a concentration less than 0.1 pmol per injection. The presence of (R)- and (S)-salsolinol was confirmed in fermented foods and beverages, while N-methylsalsolinol was not detected. On the other hand, the (R)-enantiomers of both salsolinol and N-methylsalsolinol were found to predominate in the human brain.

Beverages↗
PubMed1997

MHC affinity, peptide liberation, T cell repertoire, and immunodominance all contribute to the paucity of MHC class I-restricted peptides recognized by antiviral CTL.

MHC class I-restricted T cell responses to viral proteins focus on a limited set of peptides. To better understand this phenomenon, we examined all of the 26 nonameric peptides encoded by the influenza virus A/Puerto Rico/8/34 (PR8) conforming to the canonical Kd binding motif. Ten peptides bound strongly to Kd as assessed by a cell surface stabilization assay. Five of these 10 induced in vitro secondary CD8+ T cell responses from splenocytes derived from PR8-immunized mice. The strongest responses were induced by the two previously defined antigenic peptides, which ranked only second and fifth in relative binding affinity. To examine the limiting factors in the immunogenicity of Kd-binding peptides, we produced recombinant vaccinia viruses (rVVs) expressing cytosolic or endoplasmic reticulum (ER)-targeted peptides. rVVs expressing ER-targeted versions of the 7 peptides with the highest relative affinities for Kd rescued Kd cell surface expression in T2 cells, while those expressing the 3 lowest affinity peptides did not. The immunogenicity of several, but not all, of the highest affinity peptides was greatly enhanced when expressed as VV-encoded cytosolic or ER-targeted peptides as compared with full length proteins. We conclude that limitations in the immunogenicity of class I binding peptides reflects, in order of decreasing importance, peptide liberation by cellular proteases, T cell repertoire, and TAP-mediated peptide transport. We also observed an additional important contributing factor: suppression of T cell responses to nondominant peptides by an immunodominant peptide located in the same protein.

Animals↗
PubMed1997

Probing the non-covalent structure of proteins by amide hydrogen exchange and mass spectrometry.

The rates at which hydrogens located at peptide amide linkages in proteins undergo isotopic exchange when a protein is exposed to D2O depend on whether these amide hydrogens are hydrogen bonded and whether they are accessible to the aqueous solvent. Hence, amide hydrogen exchange rates are a sensitive probe for detecting changes in protein conformation and dynamics. Hydrogen exchange rates in proteins are most often measured by NMR or Fourier transform IR spectroscopy. After a brief introduction to model kinetics used to relate amide hydrogen exchange rates to protein structure and dynamics, information required to understand and implement a new method that uses acid proteases and mass spectrometry to determine amide hydrogen exchange rates in proteins is presented. Structural and dynamic features affecting isotopic exchange rates can be detected and localized from the deuterium levels detected by mass spectrometry in proteolytic fragments of the protein. Procedures used to adjust for isotopic exchange occurring during the analysis, to extract isotope exchange rate constants from mass spectra and to link bimodal isotope patterns to protein unfolding and structural heterogeneity are also discussed. In addition, the relative merits of using mass spectrometry or NMR combined with amide hydrogen exchange to study protein structure and dynamics are discussed. The spatial resolution of hydrogen exchange results obtained by this method is typically in the range of 1-10 residues, which is substantially less than that obtained by high-resolution NMR, but sufficient to detect many functionally significant structural changes. Advantages in the areas of sensitivity, protein solubility, detection of correlated exchange and high molecular mass proteins make this approach particularly attractive for a wide range of studies.

Amides↗
PubMed1997

Cytotoxicity of endogenous isoquinolines to human dopaminergic neuroblastoma SH-SY5Y cells.

Endogenous isoquinolines with and without catechol structure have been proposed to be neurotoxins specific for dopamine neurons. In this paper they were examined for the cytotoxicity of human dopaminergic neuroblastoma SH-SY5Y cells. The cytotoxicity was quantitatively determined using Alamar Blue assay, by which the reduction-oxidation potency in the living cells can be measured spectrometrically. 1,2-Dimethyl-6,7-dihydroxyisoquinolinium ion [1,2-DMDHIQ+], an oxidation product of a parkinsonism-inducing isoquinoline, 1(R),2(N)-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahroisoquinoline [N-methyl-(R)salsolinol, NM(R)Sal] was found to be the most potent toxin among isoquinolines examined. In general, catechol isoquinolines were more toxic than isoquinolines without catechol structure. With and without catechol structure, the oxidized isoquinolinium ion having methyl groups at C-1 and N-2 positions proved to be more cytotoxic than the simple isoquinolines. The involvement of 1,2-DMDHIQ+ to the neurotoxicity of NM(R)Sal was suggested and discussed.

Cell Survival↗
PubMed1997

Regulation of ApoE gene expression in mouse peritoneal macrophages by VLDL.

Mouse peritoneal macrophages (MPM) were incubated with ApoE-poor VLDL or ApoE-rich VLDL at same concentrations for 24 h. The ApoE mRNA content increased in both groups than that in control and the highest ApoE mRNA content was seen in MPM incubated with ApoE-poor VLDL. The results suggest that VLDL could stimulate ApoE gene expression in MPM and the ApoE-poor VLDL has more pronounced effect. We think that the ApoE secreted by MPM may be incorporated into VLDL, especially the ApoE-poor VLDL, and thereby enhance the uptake of those lipoproteins by MPM or other local cells via ApoE-mediated receptor pathways.

Animals↗
PubMed1997

Localization, quantitation, and in situ detection of specific peptide-MHC class I complexes using a monoclonal antibody.

CD8+ T lymphocytes recognize antigens as short peptides bound to MHC class I molecules. Available methods cannot determine the number and distribution of these ligands on individual cells or detect antigen-presenting cells in tissues. Here we describe a method for eliciting and identifying monoclonal antibodies specific for a particular peptide-MHC class I combination. One such antibody can identify antigen complexes with a limit of detection approaching that of T cells. We used this antibody to determine the number of peptide-class I complexes generated upon viral infection, to identify antigen-presenting cells in cell mixtures, to determine the site of peptide-MHC class I interaction inside cells, and to visualize cells bearing specific peptide-MHC class I complexes after in vivo infection. Similar antibodies may prove useful for diagnostic or therapeutic purposes in cancer, infectious diseases, and autoimmune disorders.

Animals↗
PubMed1997

Alagille syndrome is caused by mutations in human Jagged1, which encodes a ligand for Notch1.

Alagille syndrome is an autosomal dominant disorder characterized by abnormal development of liver, heart, skeleton, eye, face and, less frequently, kidney. Analyses of many patients with cytogenetic deletions or rearrangements have mapped the gene to chromosome 20p12, although deletions are found in a relatively small proportion of patients (< 7%). We have mapped the human Jagged1 gene (JAG1), encoding a ligand for the developmentally important Notch transmembrane receptor, to the Alagille syndrome critical region within 20p12. The Notch intercellular signalling pathway has been shown to mediate cell fate decisions during development in invertebrates and vertebrates. We demonstrate four distinct coding mutations in JAG1 from four Alagille syndrome families, providing evidence that it is the causal gene for Alagille syndrome. All four mutations lie within conserved regions of the gene and cause translational frameshifts, resulting in gross alterations of the protein product Patients with cytogenetically detectable deletions including JAG1 have Alagille syndrome, supporting the hypothesis that haploinsufficiency for this gene is one of the mechanisms causing the Alagille syndrome phenotype.

Alagille Syndrome↗
PubMed1997

On-column indirect photothermal interference detection for capillary zone electrophoresis.

An indirect photothermal interference detection method, which is based on the diffraction of a probe laser beam by a capillary tube, for detecting metal cations separated by capillary zone electrophoresis (CZE) is described. In this capillary photothermal interference detector, a 2 mW He-Ne probe laser is employed to provide the probe beam and an 18 mW He-Ne pump laser is used to supply the pump beam. Factors that contribute to the noise and signal in indirect photothermal interference detection in CZE, such as the noise from the scattered light caused by both the probe beam and the pump laser beam, and effects of the concentration of ethanol and NaCl on the separation efficiency, were studied. The effect of scattered light can be reduced effectively with the configuration constraints investigated for photothermal capillary absorption measurements. With Methylene Blue added to carrier electrolyte as an absorber, three typical metal cations (KI, CuII and AlIII) were separated using this system. For CuII, a 2.1 x 10(-7) mol l-1 concentration detection limit (S/N = 2) without preconcentration and a 1.02 x 10(-17) mol detection limit as absolute amount were measured, considering the optical sampling volume estimated to be 50 pl, and 1.99 x 10(6) theoretical plates were observed on the laboratory-made CE system. It was demonstrated that indirect photothermal interference detection is suitable for small capillaries and a large ionic strength range for CE analysis.

Electrophoresis, Capillary↗
PubMed1997

A wavelet-based multiresolution regularized least squares reconstruction approach for optical tomography.

In this paper, we present a wavelet-based multigrid approach to solve the perturbation equation encountered in optical tomography. With this scheme, the unknown image, the data, as well as the weight matrix are all represented by wavelet expansions, thus yielding a multiresolution representation of the original perturbation equation in the wavelet domain. This transformed equation is then solved using a multigrid scheme, by which an increasing portion of wavelet coefficients of the unknown image are solved in successive approximations. One can also quickly identify regions of interest (ROI's) from a coarse level reconstruction and restrict the reconstruction in the following fine resolutions to those regions. At each resolution level a regularized least squares solution is obtained using the conjugate gradient descent method. This approach has been applied to continuous wave data calculated based on the diffusion approximation of several two-dimensional (2-D) test media. Compared to a previously reported one grid algorithm, the multigrid method requires substantially shorter computation time under the same reconstruction quality criterion.

Algorithms↗
PubMed1997

The role of subcellular localization in initiation of apoptosis by photodynamic therapy.

Rapid initiation of apoptosis can be induced by photodynamic therapy, depending on the cell line and sensitizer employed. In this study, we evaluated the photodynamic responses to two structurally related photosensitizing agents, using the P388 murine leukemia cell line in culture. Photodamage mediated by tin etiopurpurin involved lysosomes and mitochondria and yielded a rapid apoptotic response; apoptotic nuclei were observed within 60 min after PDT. A drug analog, tin octaethylpurpurin amidine, targeted lysosomes, mitochondria and cell membranes; apoptotic nuclei were not observed until 24 h after PDT. These results, together with other recent reports, are consistent with the hypothesis that membrane photodamage can delay or prevent an apoptotic response to PDT.

Animals↗
PubMed1997

[Respiratory monitoring and high frequence jet ventilation (HFJV) in the treatment of severe chest injuries].

Twenty-eight patients with severe chest injuries were classified into 3 groups: fractures of rib, hemopneumothorax and lung injured. Their respiratory rate (RR), SpO2 and blood gas were analysed. The results showed that SpO2 and PaO2 in lung-injured group were the lowest and RR was the highest in the 3 groups. After HFJV, there was a significant rise in PaO2 and SpO2 (P < 0.05) and a gradual recovery of respiratory and pulse rates in lung-injured group. The results suggest that respiratory monitoring is important for patients with chest injuries and HFJV may be used as an effective ventilation method for treating patients with severe chest injuries.

Adult↗