Biomedical subjects

X Zhuang

Publications and source records attributed to X Zhuang.

At least 19 recordsLinked to original sources

PubMed2007

A novel conditional knockout strategy applied to serotonin receptors.

Here we demonstrate the feasibility of a doubly regulatable transgenic mouse design that allows for gene manipulation by both Cre-recombinase and the tetracycline inducible system. Using a knock-in strategy to insert both elements of the tetracycline inducible system and a neomycin (neo) cassette flanked by loxP sequences (floxed) into the wild-type locus, we generated mice that express the 5-HT(1B) receptor in a conditional manner. In the presence of a floxed neo-cassette, receptor expression was silenced. Removal of this cassette by Cre-mediated recombination led to 5-HT(1B) receptor expression, which was highly regulatable when doxycycline, a derivative of tetracycline, was administered to the mice. This system allowed for a determination of an in vivo time course of receptor half-life and recovery. Physiological studies also demonstrated that rescued 5-HT(1B) receptors were functional, and that this functionality was reversible upon treatment with doxycycline. Crossing mice where the 5-HT(1B), or the 5-HT(1A), receptors were silenced by the neo-cassette, with mice expressing either Cre-recombinase or the tetracycline transactivator (tTA) under the control of tissue-specific promoters, led to tissue-specific re-expression of these receptors. Our studies thus demonstrate the potential of this strategy for achieving both a classic knockout, as well as subsequent tissue-specific and/or inducible knockouts.

Animals↗

PubMed2006

A comparative linkage map of oilseed rape and its use for QTL analysis of seed oil and erucic acid content.

We have developed a new DH mapping population for oilseed rape, named TNDH, using genetically and phenotypically diverse parental lines. We used the population in the construction of a high stringency genetic linkage map, consisting of 277 loci, for use in quantitative genetic analysis. A proportion of the markers had been used previously in the construction of linkage maps for Brassica species, thus permitting the alignment of maps. The map includes 68 newly developed Sequence Tagged Site (STS) markers targeted to the homologues of defined genes of A. thaliana. The use of these markers permits the alignment of our linkage map with the A. thaliana genome sequence. An additional 74 loci (31 newly developed STS markers and 43 loci defined by SSR and RFLP markers that had previously been used in published linkage maps) were added to the map. These markers increased the resolution of alignment of the newly constructed linkage map with existing Brassica linkage maps and the A. thaliana genome sequence. We conducted field trials with the TNDH population at two sites, and over 2 years, and identified reproducible QTL for seed oil content and erucic acid content. The results provide new insights into the genetic control of seed oil and erucic acid content in oilseed rape, and demonstrate the utility of the linkage map and population.

Brassica napus↗

PubMed2005

OsAGAP, an ARF-GAP from rice, regulates root development mediated by auxin in Arabidopsis.

Arf (ADP-ribosylation factor) proteins, which mediate vesicular transport, have little or no intrinsic GTPase activity. They rely on the action of GTPase-activating proteins (GAPs) and guanine nucleotide exchange factors (GEFs) for their function. In the present study the OsAGAP gene in rice, which encoded a protein with predicted structure similar to ArfGAP, was identified. The purified OsAGAP-GST fusion protein was able to stimulate the GTPase activity of rice Arf. Furthermore, OsAGAP can rescue the defect of vesicular transport in the yeast gcs1 delta glo3 delta double-mutant cells. Transgenic Arabidopsis with OsAGAP constitutively expression showed reduced apical dominance, shorter primary roots, increasing number of longer adventitious roots. Many of the phenotypes can be phenocopied by treatment of exogenous indoleacetic acid level (IAA) in wild-type plants. Determination of whole-plant IAA level showed that there is a sharp increase of free IAA in OsAGAP transgenic Arabidopsis seedlings. In addition, removal of the 4-day-old shoot apex could inhibit the adventitious root formation in the transgenic seedlings. These results suggest OsAGAP, an ARF-GAP of rice, maybe involved in the mediation of plant root development by regulating auxin level.

ADP-Ribosylation Factors↗

PubMed2001

Rubbing-induced molecular reorientation on an alignment surface of an aromatic polyimide containing cyanobiphenyl side chains.

Surface lamellar decoration (SLD), surface enhanced Raman scattering (SERS) and optical second harmonic generation (SHG) experiments have been utilized to study the molecular orientation and conformation changes at a rubbed polyimide alignment-layer surface. This aromatic polyimide containing pendent cyanobiphenyl mesogens was synthesized via a polycondensation of 2,2'-bis(3,4-dicarboxy-phenyl)hexafluoropropane dianhydride (6FDA) with bis[omega-[4-(4-cyanophenyl)phenoxy]hexyl] 4,4'-diamino-2,2'-biphenyldicarboxylate (nCBBP, n = 6), abbreviated as 6FDA--6CBBP. Uniform alignment layers, possessing high pretilt angles ranging from 39 degrees to 43 degrees, have been achieved after mechanical rubbing of the polyimide thin film surface at room temperature and subsequent annealing. This is the first time that high pretilt angles have been detected to possess a negative angle (-theta(c)) with respect to the rubbing direction (i.e., opposite to the rubbing direction), considerably different from the conventional pretilt angle (theta(c)) observed along the rubbing direction. This observation is confirmed using magnetic null and SHG methods. Combined polyethylene (PE) SLD and atomic force microscopy experiments reveal that the azimuthal orientation distribution of the long axis of the edge-on PE lamellar crystals is oriented normal to the rubbing direction, indicating that the PE chains are aligned parallel to the rubbing direction. This SLD technique probes the anisotropic surface orientation of the outermost molecules of the rubbed polyimide layer. The SERS results show that prior to rubbing the surface, both the pendent cyanobiphenyls in the side chains and backbones possess nearly planar chain conformations at the polyimide surface. Mechanical rubbing causes not only tilting of the backbone moieties, such as imide-phenylene structure, but also significant conformational rearrangements of the pendent side chains at the surfaces. The molecular mechanism of this unusual alignment is due to the fact that the pendent cyanobiphenyls forms a uniformly tilted conformation on the rubbed surface, and the polar cyano groups point down toward the layer surface deduced from SHG phase measurements. This conformational rearrangement of the side chains results in the formation of fold-like bent structures on the surface, which directly leads to the long axis of cyanobiphenyls having the -theta(c) pretilt angle with respect to the rubbing direction.

Journal Article↗

PubMed2001

Adsorption of hydroxy pyridines and quinolines at the metal oxide-water interface: role of tautomeric equilibrium.

We have identified compound physical-chemical properties and structural criteria required to facilitate the adsorption of hydroxypyridines, quinolines, and pyrimidines onto aluminum(III), iron(III), and titanium(IV) oxides. We achieved this by measuring the adsorption behavior of a number of structurally related compounds, each with a nearly isolated variation in molecular structure, and systematically evaluating the effect of structural change on the nature and extent of adsorption. We find that the adsorption at the metal oxide-water interface is significant only when the oxo-hydroxy (keto-enol) tautomeric equilibrium in aqueous solution favors the hydroxy tautomer. Lack of adsorption of the oxo tautomer can be attributed to the absence of favorable electrostatic interactions between the compound and the surface, the absence of ligand groups capable of surface complexation, and the presence of strong intermolecular hydrogen bonding between ligand groups (carbonyl and amide) and water molecules. We find that adsorption of hydroxy tautomers with ortho-substituted cyclic N and -OH groups (such as trichloropyridinol) likely occurs via nonspecific electrostatic interactions, while non-ortho-substituted hydroxy tautomers (such as 8-hydroxyquinoline) and compounds such as (2-hydroxy-methylpyridine) likely adsorb via surface complexation. This study demonstrates that for compounds classified as tautomeric heterocycles it is imperative to accurately represent the predominant tautomer in aqueous solution so that the appropriate physical-chemical properties and reactivities are utilized in the evaluation of environmental fate.

Adsorption↗

PubMed2001

Orientations of side chains and adsorbed liquid crystal molecules on a rubbed polyimide surface studied by optical second harmonic generation.

Surface second harmonic generation was used to obtain approximate orientational distributions of the side chains and the adsorbed liquid crystal (LC) molecules on a rubbed side-chain polyimide surface. Both the side chains and the LC molecules appear to be well aligned in the rubbing direction but tilted away from the surface in the antirubbing direction. The latter yields a negative pretilt angle in a homogeneously aligned LC film sandwiched between two such surfaces. The side chains and the LC molecules, however, have antiparallel orientations at the surface.

Journal Article↗

PubMed2001

Hyperactivity and impaired response habituation in hyperdopaminergic mice.

Abnormal dopaminergic transmission is implicated in schizophrenia, attention deficit hyperactivity disorder, and drug addiction. In an attempt to model aspects of these disorders, we have generated hyperdopaminergic mutant mice by reducing expression of the dopamine transporter (DAT) to 10% of wild-type levels (DAT knockdown). Fast-scan cyclic voltammetry and in vivo microdialysis revealed that released dopamine was cleared at a slow rate in knockdown mice, which resulted in a higher extracellular dopamine concentration. Unlike the DAT knockout mice, the DAT knockdown mice do not display a growth retardation phenotype. They have normal home cage activity but display hyperactivity and impaired response habituation in novel environments. In addition, we show that both the indirect dopamine receptor agonist amphetamine and the direct agonists apomorphine and quinpirole inhibit locomotor activity in the DAT knockdown mice, leading to the hypothesis that a shift in the balance between dopamine auto and heteroreceptor function may contribute to the therapeutic effect of psychostimulants in attention deficit hyperactivity disorder.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

[The prognostic research of expression and relationship between Helicobacter pylori of c-met oncogene correlation with gastric mucosal proliferation].

OBJECTIVE: To determine whether there is a relationship between Helicobacter pylori (Hp) and expression of c-met oncogene and proliferating cell nuclear antigen (PCNA) in gastric mucosal lesions, and prognostic significance of gastric carcinomas(GC). METHODS: Expression of c-met and PCNA were investigated in 145 gastric mucosal lesions by using immunohistochemistry. Hp was examined by Warthin-Starry method. RESULTS: For chronic superficial gastritis (CSG), chronic atrophic gastritis and intestinal metaplasia (CAS + IM), dysplasia(DYS), early GC and advanced GC, the positive rates of c-met and PCNA were higher in IM, DYS and GC than in CSG (P < 0.05). Expressions of c-met and PCNA increased with the increasing proliferation of gastric mucosa, in rank correlation test, they had a close relationship (P < 0.01). Expressions of c-met and PCNA were correlated significantly with histologic type, serosal invasion and lymph node metastasis. In particular, the expression of c-met and PCNA were significantly higher in Borrmann type 4 GC, type 3 GC and type 1, 2 than in early GC(P < 0.05). By rank correlation test, c-met and PCNA have a close relationship (P < 0.001). Expressions of c-met of Hp positive were higher than Hp negative in intestinal GC (P < 0.05). Expressions of c-met were correlated significantly with Hp positive in CAG + IM, DYS and GC. The survival rate of patients with Hp infection was significantly poorer than that of patients with Hp non-infection. CONCLUSIONS: The expression of c-met may be is associated with proliferation and malignant transformation of gastric mucosa. These results suggest that expression of c-met may be a new prognostic factor in gastric carcinoma. Hp infection and expression of c-met may be associated with in proliferation and malignant transformation of gastric mucosa. Hp infection is associated with prognosis of gastric carcinoma.

Cell Proliferation↗

PubMed2001

[Continuous production of nisin by calcium alginate-immobilized Lactococcus lactis subsp. lacits SM526].

The attempts were made to produce nisin by immobilized cells of Lactococcus lactis subsp. lactis SM526 entrapped in calcium alginate beads. The results showed that the immobilized cell beads were intact for 90 hr under 2% of calcium alginate in 10 mmol/L CaCl2 solution. The physical stability of beads was improved by removing phosphate, citrate and acetate salts supplied in SYS3 medium. Repeated-batch fermentation utilizing immobilized cells were performed in mSYS3 medium without agitation at 32 degrees C, the concentration of nisin produced during the third cycles increased to 850 IU/mL, and the beads were still intact with little cell leakage. The immobilized beads were loaded into a sterilized glass column to continuous fermentation, nisin concentration increased to 1150 IU/mL, as high as that obtained in free-cell fermentation, and the high productivity was stable for up to 70 h under a constant supplied of the fresh mSYS3 medium.

Alginates↗

PubMed2001

[Randomized controlled trial for the effect of amrinone and aprotinin on proinflammatory cytokine release in patients with prosthetic valve replacement during perioperative period].

OBJECTIVE: To explore the effect of amrinone and aprotinin on whole-body inflammatory response in the patients with prosthetic valve replacement during perioperative period. METHODS: 24 patients undergoing prosthetic valve replacement were randomized to control group (group A, n = 8), aprotinin group (group B, n = 8) and amrinone combined with aprotinin group (group C, n = 8). In the aprotinin group, 3 x 10(6) of aprotinin was added to the priming solution of the extracorporeal circulation (ECC). In the amrinone combined with aprotinin group 3 x 10(6) of aprotinin was added to the priming solution of the ECC and amrinone began with a bolus of 1 mg/kg followed by a maintenance infusion of 8 micrograms/(kg.min). The control group received an equivalent prime volume without aprotinin. Venous blood samples were drawn before the operation, at the end of ECC, 1 hour after the end of ECC, and one day after the operation respectively. Enzyme-linked immunosorbent assay techniques were used to measure each of the cytokines. RESULTS: Before ECC, there were no differences of the levels of IL-6 and IL-8 among groups (P > 0.05). After ECC, the levels of IL-6 and IL-8 increased significantly in all groups (P < 0.05). The levels on day one after the operation were still higher than those before the operation in all groups (except the level of IL-8 in group C), but no statistical significance was observed. (P > 0.05). At 1 hour after the end of ECC, the level of IL-6 in group B was lower than that in group A, and the level of IL-6 in group C was lower than that in group B, but there was no statistically significant difference (P > 0.05); At the end of ECC, the level of IL-8 in group B was lower than that in group A and the level of IL-8 in group C was lower than that in group B, but no significant difference was noted (P > 0.05). It was also observed that the level of IL-8 was lower in group C than group A or B at 1 hour after the end of ECC. CONCLUSION: Although amrinone and aprotinin have antiinflammatory activity, but pump prime only aprotinin or aprotinin combined with amrinone may fall in preventing proinflammatory cytokine release (IL-6, IL-8) completely in patients with prosthetic valve replacement during ECC perioperative period.

Adult↗

PubMed2000

Fluorescence quenching: A tool for single-molecule protein-folding study.

By using titin as a model system, we have demonstrated that fluorescence quenching can be used to study protein folding at the single molecule level. The unfolded titin molecules with multiple dye molecules attached are able to fold to the native state. In the native folded state, the fluorescence from dye molecules is quenched due to the close proximity between the dye molecules. Unfolding of the titin leads to a dramatic increase in the fluorescence intensity. Such a change makes the folded and unfolded states of a single titin molecule clearly distinguishable and allows us to measure the folding dynamics of individual titin molecules in real time. We have also shown that fluorescence quenching can signal folding and unfolding of a small protein with only one immunoglobulin domain.

Animals↗

PubMed2000

Altered fear circuits in 5-HT(1A) receptor KO mice.

The study of genetically altered mice has been used successfully to determine the influence of different neurotransmitter receptors on fear and anxiety. Mice with a genetic deletion of the serotonin 1A receptor (5-HT(1A)R knockout [KO]) have been shown to be more fearful in a number of behavioral conflict tests, confirming the important role of this receptor in modulating anxiety. Factor analysis of the behavior of WT and 5-HT(1A)R KO mice in the open field test shows that locomotion and anxiety measures segregate independently, supporting the idea that the anxious behavior of the KO mice is not the result of altered locomotion. KO mice also show increased anxiety in the novelty-suppressed feeding task, which differs from the other conflict tests in the motivational drive of the animals. In response to a discrete aversive stimulus, foot shock, the KO mice show increased freezing and increased tachycardia. However, activation of the hypothalamic-pituitary-adrenal axis in response to stress appears to be slightly blunted in the KO animals. Together, these data support the idea that the 5-HT(1A)R modulates an important fear circuit in the brain. The dual function of the 5-HT(1A)R as both a presynaptic autoreceptor, negatively regulating serotonin activity, and a postsynaptic heteroreceptor, inhibiting the activity of nonserotonergic neurons in forebrain structures, has complicated interpretation of the anxious phenotype of these KO mice. A more complete understanding of the function of the 5-HT(1A)R awaits further study of its role in behaving animals using tissue-specific antagonists and novel transgenic mice with tissue-specific expression of the receptor.

Animals↗

PubMed2000

G(olf)alpha mediates dopamine D1 receptor signaling.

It is generally assumed that the coupling of dopamine D1 receptors to adenylyl cyclase is mediated by the stimulatory GTP-binding protein G(s). However, the striatum contains little G(s)alpha subunit, whereas it expresses high levels of G(olf)alpha, a close relative of G(s)alpha that is also expressed in olfactory receptor neurons. We used G(olf)alpha knockout mice to examine the functional coupling of D1 receptors. We found that these mice showed no hyperlocomotor response to either the D1 agonist SKF-81297 or the psychostimulant cocaine. Moreover, G(olf)alpha knockout mice did not display cocaine-induced c-fos expression in the striatum. Finally, in the absence of G(olf)alpha, striatal D1 receptors have a decreased affinity for dopamine. Thus coupling to G(olf)alpha appears to mediate D1 signaling in the striatum.

Animals↗

PubMed2000

A single-molecule study of RNA catalysis and folding.

Using fluorescence microscopy, we studied the catalysis by and folding of individual Tetrahymena thermophila ribozyme molecules. The dye-labeled and surface-immobilized ribozymes used were shown to be functionally indistinguishable from the unmodified free ribozyme in solution. A reversible local folding step in which a duplex docks and undocks from the ribozyme core was observed directly in single-molecule time trajectories, allowing the determination of the rate constants and characterization of the transition state. A rarely populated docked state, not measurable by ensemble methods, was observed. In the overall folding process, intermediate folding states and multiple folding pathways were observed. In addition to observing previously established folding pathways, a pathway with an observed folding rate constant of 1 per second was discovered. These results establish single-molecule fluorescence as a powerful tool for examining RNA folding.

Animals↗

PubMed2000

Nonlinear optical studies of liquid crystal alignment on a rubbed polyvinyl alcohol surface

Sum-frequency vibrational spectroscopy and second-harmonic generation have been used to measure the orientational distributions of the polymer chains and adsorbed 8CB liquid crystal molecules on a rubbed polyvinyl alcohol surface. Results show that the polymer chains at the surface appear to be well aligned by rubbing, and the adsorbed liquid crystal molecules are aligned, in turn, by the surface polymer chains. Strong correlation exists between the orientational distributions of the polymer chains and the liquid crystal molecules, indicating that the surface-induced bulk alignment of a liquid crystal film by rubbed polymer surfaces is via an orientational epitaxylike mechanism.

Journal Article↗

PubMed2000

[Bone marrow transplantation for beta-thalassemia major].

OBJECTIVE: To examine the feasibility of bone marrow hematopoietic stem cell transplantation for thalassemia major. METHODS: Bone marrow transplantation was performed on a 4-year-old patient with beta-thalassemia major, whose gene mutation was CD41-42/654. The donor was his brother. In the 850ml bone marrow, the nucleated cells were 5.6x10(8)/kg, CD(+)(34) cells 7.8 x 10(6)/kg, and colony-forming-unit-granulocyte-macrophages(CFU-GM) 5.7x10(5)/kg. HLA was one site mismatched, while RBC type matched. Pre-transplant conditions included Busulfan 16mg/kg, cyclophosphamide 200mg/kg and lymphoglobuline 88mg/kg. Cyclosporine and methotrexate were used for prevention of graft-versus-host disease(GVHD). RESULTS: After transplantation, the patient had grade II acute GVHD and cytomegalovirus(CMV) interstitial pneumonia; he was cured. White blood cells(WBC) and neutrophil granulocytes recovered to 1.1 x 10(9)/L and 0.4 x10(9)/L respectively on day 14 post transplantation. WBC was 4.5 x 10(9)/L on day 18, and descended for a time during treating interstitial pneumonia with Ganciclovir. Platelet(Plt) exceeded 50 x 10(9)/L on day 86 and recovered to normal 5 mothers and a half post transplantation. Hb reached 106g/L on day 128. The patient received the last blood transfusion on day 103. Before transplantation, the patient had to receive 200ml blood infusion per month for maintaining Hb 60-90g/L; after transplantation, his Hb kept up >110g/L for 6 months without blood transfusion. The gene type had changed to donor's CD41-42/N heterozygen. CONCLUSION: This is the first report on successful transplantation of bone marrow stem cell for thalassemia major in China, suggesting a new way to treat the disease and to expand the use of BMT. For treatment of CMV interstitial pneumonia post-transplantation, Ganciclovir should be dose enough and be used for at least 2 months.

Child, Preschool↗

PubMed2000

[Low expression of nm23-H1 mRNA and its protein in breast cancer].

OBJECTIVE: To explore the expression of nm23-H1 mRNA and its protein in breast cancer and its correlation to the biologic behavior. METHODS: RT-PCR and immunohistochemical method were employed to detect the expression of nm23-H1 mRNA and its protein in 58 breast cancer tissues. RESULTS: Low level expression of nm23-H1 mRNA and protein was shown in 44.8% and 48.2% of examined cases respectively. The low expression of nm23-H1 mRNA was correlated, but not always parallel to the protein expression. The low level expression of nm23-H1 mRNA or the protein was significantly associated with lymphatic metastasis of the cancer. CONCLUSION: Examination of nm23-H1 expression may be of significance in evaluating metastatic potentiality and prognosis of breast cancer.

Breast Neoplasms↗

PubMed2000

Acupuncture treatment of Parkinson's disease--a report of 29 cases.

It can be concluded that acupuncture possesses definite therapeutic effectiveness for Parkinson's disease, which is mainly represented by improvement in the clinical symptoms and signs, delaying of the disease's progression, decrease in the dosage of anti-parkinsonian drug, and expectant treatment of the complications and symptoms induced by the drug side-effects.

Acupuncture Therapy↗