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Biomedical subjects

Q Yuan

Publications and source records attributed to Q Yuan.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Polymorphism of HLA-DRB1, DQB1 in the Hans of north China]

OBJECTIVE: To understand polymorphism of HLA-DRB1, DQB1 in the Hans of north China and obtain more comprehensive and accurate data on genetics at DNA level. METHODS: Polymerase chain reaction-sequence specific primers (PCR-SSP) were used to determine HLA-DRB1, DQB1 alleles in 107 unrelated healthy Han individuals of north China. RESULTS: The authors determined 14 DRB1, 9 DQB1 alleles, which included not only the allele frequencies that corresponded to the gene frequencies of DR, DQ loci determined by other 9 cooperating labs but also the allele frequencies of DRB1*15, DRB1*16, DQB1*0301, DQB1*0302, DQB1*0303, DQB1*05, DQB1*0601, DQB1*0602, and DQB1*0604 that other serology labs did not report. CONCLUSION: This study has obtained a more comprehensive and accurate data set of the normal allele frequencies and linkage disequilibrium parameters of HLA-DRB1,DQB1 in the Hans of north China, which may be of significance in the studies on population genetics and disease association.

Journal Article↗
PubMed1999

Cascaded MRI-SPAMM for LV motion analysis during a whole cardiac cycle.

We present a new paradigm which incorporates multiple sets of tagged MRI data (MRI-SPAMM) acquired in a cascaded fashion in order to estimate the full 3-D motion of the left ventricle (LV) during its entire cardiac cycle. Our technique is based on an extension of our volumetric physics-based deformable models, whose parameters are functions. Using these parameters, we can characterize the local shape variation of an object with a small number of intuitive parameters. By integrating a cascaded sequence of SPAMM data sets into our modeling technique, we have extended the capability of the MRI-SPAMM technique and have provided an accurate representation of the LV motion during the full cardiac cycle (from end-diastole to end-diastole) to better understand cardiac mechanics.

Humans↗
PubMed1999

Identification of mimotope peptides which bind to the mycotoxin deoxynivalenol-specific monoclonal antibody.

Monoclonal antibody 6F5 (mAb 6F5), which recognizes the mycotoxin deoxynivalenol (DON) (vomitoxin), was used to select for peptides that mimic the mycotoxin by employing a library of filamentous phages that have random 7-mer peptides on their surfaces. Two phage clones selected from the random peptide phage-displayed library coded for the amino acid sequences SWGPFPF and SWGPLPF. These clones were designated DONPEP.2 and DONPEP.12, respectively. The results of a competitive enzyme-linked immunosorbent assay (ELISA) suggested that the two phage displayed peptides bound to mAb 6F5 specifically at the DON binding site. The amino acid sequence of DONPEP.2 plus a structurally flexible linker at the C terminus (SWGPFPFGGGSC) was synthesized and tested to determine its ability to bind to mAb 6F5. This synthetic peptide (designated peptide C430) and DON competed with each other for mAb 6F5 binding. When translationally fused with bacterial alkaline phosphatase, DONPEP.2 bound specifically to mAb 6F5, while the fusion protein retained alkaline phosphatase activity. The potential of using DONPEP.2 as an immunochemical reagent in a DON immunoassay was evaluated with a DON-spiked wheat extract. When peptide C430 was conjugated to bovine serum albumin, it elicited antibody specific to peptide C430 but not to DON in both mice and rabbits. In an in vitro translation system containing rabbit reticulocyte lysate, synthetic peptide C430 did not inhibit protein synthesis but did show antagonism toward DON-induced protein synthesis inhibition. These data suggest that the peptides selected in this study bind to mAb 6F5 and that peptide C430 binds to ribosomes at the same sites as DON.

Amino Acid Sequence↗
PubMed1999

[Polymorphism of HLA-DRB1, DQB1 in the Hans of north China].

OBJECTIVE: To understand polymorphism of HLA-DRB1, DQB1 in the Hans of north China and obtain more comprehensive and accurate data on genetics at DNA level. METHODS: Polymerase chain reaction-sequence specific primers (PCR-SSP) were used to determine HLA-DRB1, DQB1 alleles in 107 unrelated healthy Han individuals of north China. RESULTS: The authors determined 14 DRB1, 9 DQB1 alleles, which included not only the allele frequencies that corresponded to the gene frequencies of DR, DQ loci determined by other 9 cooperating labs but also the allele frequencies of DRB1*15, DRB1*16, DQB1*0301, DQB1*0302, DQB1*0303, DQB1*05, DQB1*0601, DQB1*0602, and DQB1*0604 that other serology labs did not report. CONCLUSION: This study has obtained a more comprehensive and accurate data set of the normal allele frequencies and linkage disequilibrium parameters of HLA-DRB1, DQB1 in the Hans of north China, which may be of significance in the studies on population genetics and disease association.

Alleles↗
PubMed1999

[Apoptosis and necrosis of neuron after focal ischemia in brain of rats].

This article reports the apoptosis and necrosis of neurons following ischemia-reperfusion in the brain of rats. The focal ischemia model was established by occluding the middle cerebral artery for 2 h and reperfusing for 0.5-48 h. The neuronal changes were investigated by HE staining, TUNEL and agarose gel-electrophoresis. The foci of ischemia were in the preoptic area, striatum and cortex. At 0.5 h of reperfusion, there were quite a few apoptotic neurons in the preoptic ischemic focus, but only a few scattered apoptotic cells were seen in the striatum and cortex. During 3-6 h of reperfusion, the number of apoptotic cells increased and the necrotic cells appeared. The number of apoptotic cells reached a peak at 12-24 h and the in morphology varied, and they were mainly located in the inner boundary of infarct. At 48 h, the apoptotic cells decreased; and the necrotic cells increased. Agarose gel-electrophoresis showed the dense smear and ladder pattern of DNA fragments, the apoptosis and necrosis of neurons coexisted, and apoptosis contributed to the enlargement of the ischemic infarct.

Animals↗
PubMed1999

[Effects of reperfusion on neuronal changes and macrophagic response after transient focal ischemia--reperfusion of brain in rats].

Male SD rats(n = 29) were subjected to 2 hours' middle cerebral artery occlusion and were killed at various times of reperfusion (0.5-48 hours). The histological features of neuronal changes, the macrophagic response and the relationship between them were investigated. The neurons underwent acute changes(shrinking or swollen), and the pyknotic apoptotic neurons were occasionally seen within 3 hours. The number of apoptotic neurons increased with recirculation time. The scattered red neurons and ghost cells were first found at 6 hours of reperfusion. Many apoptotic neurons, apoptotic bodies were detected in the penumbra of ischemic core at 48 hours. Lectin histochemistry with GSI-B4 was performed to observe the macrophage. The results showed the active microglia and macrophage from meninges presented at 12 hours. The macrophages from parenchyma vessels appeared at 24 hours. Reactive microglia and extrinsic macrophage aggregated into the band of macrophage which phagocytized the apoptotic neurons. The results indicate that, firstly, it is important to prevent the neuronal apoptosis and reduce the volume of infarct in stroke patients; secondly, irreversible neuronal lesions simultaneously stimulate microglial activation and the presence of extrinsic macrophages from meninges was earlier than the appearance of the macrophages from parenchyma blood-monocytes. The authors also suggest that the data on the neuronal changes over time after ischemia and reperfusion be useful reference materials for selecting the most timely medication to treat cerebral infarction.

Animals↗
PubMed1999

[Mechanism study of muscle injury from high tension (I)--The biomechanical effect of training on muscle injury from downhill running in rats].

In this experiment, we tested the biomechanical characteristics of rat's fast and slow skeletal injury from downhill running at different times. The result indicates that the mechanical properties of fast and slow skeletal muscle, including maximum tensile strength, maximum strain, elasticity and energy absorption, gradually stregthen with extended time (not more than 48 hours) after eccentric exercise-induced injury. On the other hand, the maximum strain of slow muscle is higher than that of fast muscle.

Animals↗
PubMed1998

Generation of a novel stem cell factor-dependent mast cell progenitor.

Tissue mast cell development requires stem cell factor (SCF), whereas helminth-induced intestinal mucosal mast cell hyperplasia also requires T cell-derived factors such as IL-3. We generated progenitor mast cells (PrMC) from mouse bone marrow cells (BMC) in vitro with a triad of SCF, IL-6, and IL-10 that exhibit IL-3-mediated mitogenic and maturation responses. SCF/IL-6/IL-10 transiently elicited a cell subpopulation with the phenotype (c-kit(high)Thy-1(low)) of fetal blood promastocytes at 3 wk of culture that progressed within 1 wk to FcepsilonRI-bearing PrMC, designated PrMCTriad. PrMCTriad lacked mouse mast cell carboxypeptidase A (mMC-CPA) protein, required SCF for IL-3-driven thymidine incorporation, and responded to SCF plus IL-3 with strong mMc-CPA immunoreactivity, clarifying distinct sequential roles for SCF and IL-3 in mast cell development. PrMCTriad, arising from BMC through promastocytes, are metamastocytes that acquire microenvironmentally determined phenotypic features.

Animals↗
PubMed1998

In vivo human cervical spinal cord deformation and displacement in flexion.

STUDY DESIGN: In vivo, quasi-static distortion of the human cervical spinal cord was measured in five volunteers during flexion of the neck using a motion-tracking magnetic resonance imaging technique. OBJECTIVES: To measure cord distortion and movement in living subjects. SUMMARY OF BACKGROUND DATA: In situ spinal cord measurements in human and rhesus monkey cadavers taken at full flexion demonstrate that the entire cervical cord elongates approximately 10% of its length at a neutral position, but no data are available at other angles of flexion, or in living subjects. METHODS: The spatial modulation of magnetization pulse sequence created a series of parallel lines in the image that deform with the tissue. A custom-designed device was built to guide the flexion of the neck and enhance motion reproducibility. Midsagittal plane images were acquired before and after flexion. The tagged line pattern in each pair of magnetic resonance images was compared to compute distortion and movement of the cervical spinal cord at varying degrees of flexion. RESULTS: Between a neutral posture and full flexion, the entire cord (C2-C7) elongated linearly with head flexion, increasing 10% and 6% of its initial length along the posterior and anterior surfaces, respectively. Average displacement was on the order of 1-3 mm, and varied with region. Specifically, the upper cord showed caudad movement in the spinal canal, and the lower cord moved cephalad, again with larger movements on the posterior surface. CONCLUSIONS: The cervical cord elongates and displaces significantly during head flexion in human volunteers, offering valuable information regarding the normal milieu of the cord.

Adult↗
PubMed1998

Applications of Ion Microscopy and In Situ Electron Microscopy to the Study of Electronic Materials and Devices.

: We discuss the application of ion microscopy and in situ electron microscopy to the study of electronic and optical materials and devices. We demonstrate how the combination of in situ transmission electron microscopy and focused ion beam microscopy provides new avenues for the study for such structures, enabling extension of these techniques to the study of dopant distributions, nanoscale stresses, three-dimensional structural and chemical reconstruction, and real-time evolution of defect microstructure. We also discuss in situ applications of thermal, mechanical, electrical, and optical stresses during transmission electron microscopy imaging.

Journal Article↗
PubMed1998

[Numerical taxonomy of bifidobacteria and homology analysis of some representative strains].

Fifty five strains of bifidobacteria belonging to Bifidobacterium from various sources were studied by using numerical taxonomic techniques. These organisms included 13 reference strains and 42 newly isolated strains (19 strains of human sources, 25 strains of animal sources and 11 strains obtained from sewage). Several strains isolated from the animals weren't isolated before. Overall similarities of the strains for 75 characters contained morphological, physiological and biochemical characteristics and antibacterial susceptibility were determined. Dendrogram of numerical analysis based on unweighted pair cluster average linkage were achieved. Five clusters were defined at 70% Sm level. The relationships of these strains among five clusters were analysed. The strains of human sources were basically separated from the animal strains, and the sewage strains were distributed between the animal clusters and the human clusters. On the basis of the numerical analysis, the G + C content of DNA of some representative strains among these clusters were measured. Biotin-labeled DNA segments, complementary to variable regions of 16S rRNA, were amplified using PCR as probes. In the dot-blot hybridization the relationships of DNA segments among some strains were discussed. The test results showed that the homologies among the strains in same species and various species were different. The studies are valuable for further research in the relationships of some species among bifidobacteria of various sources.

Animals↗
PubMed1998

[Measuring trace germanium in vegetables with the spectrofluorometric method].

A spectrofluorometric method to measure trace germanium in vegetables was established. Results showed that the detection limit of the method was 0.569 ng/g, the accuracy of determination on the 1 microg Ge content was +/- 3.59%. The content of Ge in vegetables could be calculated from the standard adding method without extraction when using mixed acid digestion.

Calibration↗
PubMed1998

Kinematic response of the neck to voluntary and involuntary flexion.

METHODS: The dynamic head-neck responses of human subjects and cadavers undergoing involuntary impact loading conditions have been studied extensively in order to define the kinematics of the neck undergoing rapid movements, but little detailed information is available regarding slower, voluntary motions. In this study, the dynamic kinematics of head/neck complex during subject-controlled, or voluntary head motion have been investigated to compare with the kinematics to involuntary response. Five male human subjects experienced two-types of posterior/anterior neck flexion: flexion initiated under their own volition, and flexion in response to -15Gx acceleration of the torso. Tri-axial photo target mounts were placed on a custom-fit plate at the mouth, on the first thoracic vertebra, and on the sled. High speed movie cameras captured the photo target motion. Linear and angular displacement and velocity of the head and T1 and sled were computed using customized data-processing software. The neck kinematics were represented by a 2-pin linkage which connected the anatomical origins of the head and T1. RESULTS: The results show that maximum neck flexion relative to the torso was not significantly different between the voluntary and involuntary head motions, but that the head motion was significantly greater during the involuntary sled maneuvers. Maximum flexion velocities of 450 and 1236 degrees x s(-1) were sustained during the voluntary and involuntary maneuvers, respectively. CONCLUSION: These findings are important in understanding the kinematics of the human head/neck complex undergoing rapid and slow movements, and will be valuable in future studies determining a realistic physiological performance corridor for the human neck.

Acceleration↗
PubMed1997

Human peripheral blood eosinophils express a functional c-kit receptor for stem cell factor that stimulates very late antigen 4 (VLA-4)-mediated cell adhesion to fibronectin and vascular cell adhesion molecule 1 (VCAM-1).

We evaluated mature peripheral blood eosinophils for their expression of the surface tyrosine kinase, c-kit, the receptor for the stromal cell-derived cytokine, stem cell factor (SCF). Cytofluorographic analysis revealed that c-kit was expressed on the purified peripheral blood eosinophils from 8 of 8 donors (4 nonatopic and 4 atopic) (mean channel fluorescence intensity 2.0- 3. 6-fold, average 2.8 +/- 0.6-fold, greater than the negative control). The uniform and selective expression of c-kit by eosinophils was confirmed by immunohistochemical analysis of peripheral blood buffy coats. The functional integrity of c-kit was demonstrated by the capacity of 100 ng/ml (5 nM) of recombinant human (rh) SCF to increase eosinophil adhesion to 3, 10, and 30 microg/ml of immobilized FN40, a 40-kD chymotryptic fragment of plasma fibronectin, in 15 min by 7.7 +/- 1.4-, 5.3 +/- 3.3-, and 5.4 +/- 0. 2-fold, respectively, and their adhesion to 0.1, 0.5, and 1.0 microg/ml vascular cell adhesion molecule-1 (VCAM-1), by 12.7 +/- 9. 2-, 3.8 +/- 2.5-, and 1.7 +/- 0.6-fold, respectively. The SCF-stimulated adhesion occurred without concomitant changes in surface integrin expression, thereby indicating an avidity-based mechanism. rhSCF (100 ng/ml, 5 nM) was comparable to rh eotaxin (200 ng/ml, 24 nM) in stimulating adhesion. Cell adhesion to FN40 was completely inhibited with antibodies against the alpha4 and beta1 integrin subunits, revealing that the SCF/c-kit adhesion effect was mediated by a single integrin heterodimer, very late antigen 4 (VLA-4). Thus, SCF represents a newly recognized stromal ligand for the activation of eosinophils for VLA-4-mediated adhesion, which could contribute to the exit of these cells from the blood, their tissue localization, and their prominence in inflammatory lesions.

Cell Adhesion↗
PubMed1997

Molecular cloning, expression, and characterization of a functional single-chain Fv antibody to the mycotoxin zearalenone.

The heavy-chain and kappa light-chain variable region genes of an antizearalenone hybridoma cell line (2G3-6E3-2E2) were isolated by PCR and joined by a DNA linker encoding peptide (Gly4Ser)3 as a single-chain Fv (scFv) DNA fragment. The scFv DNA fragment was cloned into a phagemid (pCANTAB5E) and expressed as a fusion protein with E tag and phage M13 p3 in Escherichia coli TG1. In the presence of helper phage M13K07, the scFv fusion protein was displayed on the surfaces of recombinant phages. High-affinity scFv phages were enriched through affinity selection in microtiter wells coated with zearalenone-ovalbumin conjugate. The selected recombinant phages were used to infect E. coli HB2151 for the production of soluble scFv antibodies. One selected clone (pQY1.5) in HB2151 secreted a soluble scFv antibody (QY1.5) with a high zearalenone-binding affinity (concentration required for 50% inhibition of binding, 14 ng/ml), similar to that of parent monoclonal antibody in a competitive indirect enzyme-linked immunosorbent assay. However, scFv QY1.5 exhibited higher cross-reactivity with zearalenone analogs and had greater sensitivity to methanol destabilization than the parent monoclonal antibody did. Nucleotide sequence analyses revealed that the light-chain portion of scFv QY1.5 had a nucleotide sequence identity of 97% to a mouse germ line gene VK23.32 in mouse kappa light-chain variable region subgroup V, whereas the heavy-chain nucleotide sequence was classified as mouse heavy-chain subgroup III (D) but without any closely related members having highly homologous complementarity-determining region sequences. The potential of soluble scFv QY1.5 for routine screening of zearalenone and its analogs was demonstrated with zearalenone-spiked corn extracts.

Amino Acid Sequence↗
PubMed1997

Immobilized cells with endocellular enzymes improved by the permealizing and crosslinking treatment.

In order to achieve high activity of enzymatic catalysis, the method of permealizing and crosslinking treatment has been suggested for immobilizing cells with endocellular enzymes. Polyethene-polyamine and glutardehyde were used to enhance the activity and stability of E. coli having aspartase entrapped in k-carrageenan gel and intact P. dacunhae cells having aspartate-beta-decarbonoxylase. The strength and enlargement effects, which favor the performance of catalysis in a packed bed reactor and a membrane reactor, respectively, were also obtained from the experiment results.

Aspartate Ammonia-Lyase↗
PubMed1996

Intracellular single-chain antibody inhibits integrin VLA-4 maturation and function.

A single-chain antibody construct was prepared containing the VH and VL regions of anti-(integrin alpha 4) antibody HP1/2, an interchain linker and a KDEL endoplasmic reticulum retention sequence. Intracellular expression of this single-chain antibody caused cell-surface expression of alpha 4 beta 1 integrin to be decreased by 80% on selected RD cells and by 65-100% on selected Jurkat cells, relative to mock transfectants. Immunoprecipitation from single-chain-antibody-transfected cells showed that the single-chain antibody was complexed with the integrin alpha 4 and beta 1 subunits, and the diminished sizes of alpha 4 and beta 1 were consistent with impaired maturation. Furthermore, cell adhesion to alpha 4 beta 1 ligands [VCAM-1 (vascular cell adhesion molecule-1), FN40 (40 kDa chymotryptic fragment of fibronectin) and CS1] was greatly impaired in both RD and Jurkat cells, and cell spreading on immobilized FN40 protein was almost completely eliminated. Thus we conclude that intracellular single-chain antibodies may be used to reduce or eliminate cell-surface expression of a specific integrin, with specific functional consequences. This approach should be generally applicable to other integrin subunits.

Animals↗