Biomedical subjects

T Zhao

Publications and source records attributed to T Zhao.

At least 19 recordsLinked to original sources

PubMed2006

Granzyme K cleaves the nucleosome assembly protein SET to induce single-stranded DNA nicks of target cells.

Although granzymes (Gzms) A- and B-induced cell death pathways have been defined, little is known about how other orphan Gzms function in CTL-mediated cytotoxicity. GzmK and A are tryptases among all the Gzms of humans and they are closely linked on the same chromosome. In this study, we showed that GzmK can be efficiently delivered into target cells with a cationic lipid protein transfection reagent Pro-Ject. We found human GzmK triggers rapid cell death independently of caspase activation. The features of death are characterized by rapid externalization of phosphatidylserine, nuclear morphological changes and single-stranded DNA nicks. GzmK hydrolyzes the nucleosome assembly protein SET in its recombinant and native forms or in intact cells. Cleavage of SET by GzmK abrogates its nucleosome assembly activity. After GzmK loading, SET and DNase NM23H1 rapidly translocate into the nucleus and SET is cleaved, where the nuclease activity of NM23H1 is activated to nick chromosomal DNA.

Caspases↗

PubMed2006

Electrical control of antiferromagnetic domains in multiferroic BiFeO3 films at room temperature.

Multiferroic materials, which offer the possibility of manipulating the magnetic state by an electric field or vice versa, are of great current interest. In this work, we demonstrate the first observation of electrical control of antiferromagnetic domain structure in a single-phase multiferroic material at room temperature. High-resolution images of both antiferromagnetic and ferroelectric domain structures of (001)-oriented multiferroic BiFeO3 films revealed a clear domain correlation, indicating a strong coupling between the two types of order. The ferroelectric structure was measured using piezo force microscopy, whereas X-ray photoemission electron microscopy as well as its temperature dependence was used to detect the antiferromagnetic configuration. Antiferromagnetic domain switching induced by ferroelectric polarization switching was observed, in agreement with theoretical predictions.

Journal Article↗

PubMed2005

Electric field effect in diluted magnetic insulator anatase Co: TiO2.

An external electric field induced reversible modulation of a room temperature magnetic moment and coercive field is achieved in an epitaxial and insulating thin film of dilutely cobalt-doped anatase TiO2. This first demonstration of an electric field effect in any oxide-based diluted ferromagnet is realized in a high quality epitaxial heterostructure of PbZr(0.2)Ti(0.8)O(3)/Co: TiO(2)/SrRuO(3) grown on (001) LaAlO3. The observed effect, which is about 15% in strength in a given heterostructure, can be modulated over several cycles. Possible mechanisms for electric field induced modulation of insulating ferromagnetism are discussed.

Journal Article↗

PubMed2005

Cell populations and adhesion molecules expression in conjunctiva before and after bone marrow transplantation.

We were interested to analyse the composition of the cellular infiltrate and adhesion molecules expression in the conjunctiva before and at least one hundred days after autologous and allogenic bone marrow transplantation (BMT) and its relation with the presence of dry eye. We used immunohistochemistry on cryopreserved human conjunctiva with monoclonal antibodies to T-lymphocytes (CD3, CD4 and CD8), B-lymphocytes (CD19), macrophages (CD14), natural killer cells (NK, CD57), intercellular adhesion molecule 1 (ICAM-1), E-selectin, vascular cell adhesion molecule-1 (VCAM-1), lymphocyte function associated antigen-1 (LFA-1), very late antigen-4 (VLA-4), interleukin 2 receptor (IL2r, CD25) and HLA-DR. Our autologous recipients had no graft-versus-host disease (GVHD) but allogenic patients had chronic GVHD. After autologous BMT the conjunctiva had significantly more: (1) T lymphocytes (CD3+, CD4+, CD8+) in the epithelium; (2) CD4+ and CD14+ cells in the stroma; and (3) VLA-4 expression in the stroma than before BMT. After allogenic BMT, the conjunctiva exhibited a significant increase of: (1) CD3+ and CD14+ cells in the epithelium; (2) T lymphocytes (CD3+, CD4+, CD8+) and CD14+ cells in the stroma; and (3) VLA-4 and LFA-1 expression in the stroma than before BMT. After the engraftment, the comparison between autologous and allogenic recipients revealed that: (1) there were no significant differences in adhesion molecule expression; (2) the epithelium of autologous recipients had significantly more CD3+ cells; and (3) the stroma of allogenic patients had significantly more CD3+ and CD8+ cells. Among allogenic recipients, CD14+ cells were significantly increased both in the epithelium and in the stroma of patients with signs or symptoms of dry eye in comparison with patients without ocular involvement. Additionally, those having keratoconjunctivitis sicca (KCS) had CD4/CD8 ratios significantly higher than those without KCS. In conclusion, in the conjunctiva after autologous BMT a subclinical cell mediated immune reaction seems to take place. The conjunctivitis of chronic GVHD is complex, with T cells and macrophages dramatically contributing to the process.

Acute Disease↗

PubMed2005

Thermoregulation responses of broiler chickens to humidity at different ambient temperatures. I. One week of age.

Three trials were conducted to investigate the effect of RH (35, 60, and 85%) on thermoregulation of 1-wk-old broiler chickens at different temperatures (35, 30, and 25 degrees C). The response to humidity in rectal temperature and plumage temperature at the back and breast within 24 h after exposure were recorded at 5 time points (1,4,8,16, and 24 h). Humidity affected the thermoregulation of 1-wk-old broiler chickens by redistributing heat within the body at high, low, and thermoneutral temperatures. The redistribution of heat resulted in decreased rectal temperature and increased peripheral temperature, which were, respectively, beneficial and unfavorable at high and low temperatures. These results suggested that feedback effects of surface temperature on core temperature also exist in poultry, as already observed in mammals, and could be induced not only by changed ambient temperature but also by the changes in humidity at high temperature. The disturbance of thermal equilibrium could not be established solely by changes in RT, but rather core and surface temperatures had to be considered. The daily rhythms in rectal and surface temperatures were affected by humidity.

Aging↗

PubMed2005

Muscle infarction involving muscles of abdominal and thoracic walls in diabetes.

AIMS: This paper presents two cases of muscle infarction involving four major muscles of the anterior abdominal wall (case 1) and pectoralis major (case 2) in individuals with diabetes. METHODS: Erythrocyte sedimentation rate (ESR) and creatine kinase (CK) were measured and Doppler ultrasound, an open muscle biopsy (case 1) and magnetic resonance imaging (MRI) (case 2) were performed. RESULT: The diagnosis of muscle infarction was made by histological findings and MRI images with hyper-intensive signals on a gadolinium-enhanced T2-weighted sequence, respectively. Both patients were treated with bed rest, immobilization of the involved extremities, analgesia and intensive insulin therapy. In addition, anticoagulant drugs such as low molecular weight heparin sodium and cilostazol, and some traditional Chinese medicines such as ligustrazine and salvia miltiorrhiza were administered. The symptoms of both patients resolved gradually after 3 weeks. However, muscle infarction reoccurred in case 1 on the opposite side of the abdomen and recovered after 40 days. CONCLUSIONS: This is the first report of muscle infarction involving the muscles of anterior abdominal walls and pectoralis major in diabetes. MRI is the best non-invasive technique and T2-weighted imaging is the most valuable method for the diagnosis. In addition to supportive therapy, administration of anticoagulant agents and some Chinese traditional medicine may be useful in symptom relief.

Abdominal Muscles↗

PubMed2004

Self-assembled single-crystal ferromagnetic iron nanowires formed by decomposition.

Arrays of perpendicular ferromagnetic nanowires have recently attracted considerable interest for their potential use in many areas of advanced nanotechnology. We report a simple approach to create self-assembled nanowires of alpha-Fe through the decomposition of a suitably chosen perovskite. We illustrate the principle behind this approach using the reaction 2La(0.5)Sr(0.5)FeO(3) --> LaSrFeO(4) + Fe + O(2) that occurs during the deposition of La(0.5)Sr(0.5)FeO(3) under reducing conditions. This leads to the spontaneous formation of an array of single-crystalline alpha-Fe nanowires embedded in LaSrFeO(4) matrix, which grow perpendicular to the substrate and span the entire film thickness. The diameter and spacing of the nanowires are controlled directly by deposition temperature. The nanowires show uniaxial anisotropy normal to the film plane and magnetization close to that of bulk alpha-Fe. The high magnetization and sizable coercivity of the nanowires make them desirable for high-density data storage and other magnetic-device applications.

Crystallization↗

PubMed2004

Multiferroic BaTiO3-CoFe2O4 Nanostructures.

We report on the coupling between ferroelectric and magnetic order parameters in a nanostructured BaTiO3-CoFe2O4 ferroelectromagnet. This facilitates the interconversion of energies stored in electric and magnetic fields and plays an important role in many devices, including transducers, field sensors, etc. Such nanostructures were deposited on single-crystal SrTiO3 (001) substrates by pulsed laser deposition from a single Ba-Ti-Co-Fe-oxide target. The films are epitaxial in-plane as well as out-of-plane with self-assembled hexagonal arrays of CoFe2O4 nanopillars embedded in a BaTiO3 matrix. The CoFe2O4 nanopillars have uniform size and average spacing of 20 to 30 nanometers. Temperature-dependent magnetic measurements illustrate the coupling between the two order parameters, which is manifested as a change in magnetization at the ferroelectric Curie temperature. Thermodynamic analyses show that the magnetoelectric coupling in such a nanostructure can be understood on the basis of the strong elastic interactions between the two phases.

Journal Article↗

PubMed2003

Dynamics of ferroelastic domains in ferroelectric thin films.

Dynamics of domain interfaces in a broad range of functional thin-film materials is an area of great current interest. In ferroelectric thin films, a significantly enhanced piezoelectric response should be observed if non-180 degrees domain walls were to switch under electric field excitation. However, in continuous thin films they are clamped by the substrate, and therefore their contribution to the piezoelectric response is limited. In this paper we show that when the ferroelectric layer is patterned into discrete islands using a focused ion beam, the clamping effect is significantly reduced, thereby facilitating the movement of ferroelastic walls. Piezo-response scanning force microscopy images of such islands in PbZr0.2Ti0.8O3 thin films clearly point out that the 90 degrees domain walls can move. Capacitors 1 microm2 show a doubling of the remanent polarization at voltages higher than approximately 15 V, associated with 90 degrees domain switching, coupled with a d33 piezoelectric coefficient of approximately 250 pm V-1 at remanence, which is approximately three times the predicted value of 87 pm V-1 for a single domain single crystal.

Biomedical Engineering↗

PubMed2003

Frequencies of the major alleles of the Diego, Dombrock,Yt, and Ok blood group systems in the Chinese Han, Hui, and Tibetan nationalities.

The frequencies of the major alleles of the Diego,Dombrock,Yt,and Ok blood group systems in the Chinese Han, Hui, and Tibetan nationalities were determined using a DNA-based PCR-sequence-specific primers (SSP) genotyping technique. The frequencies of Dia, Dib, Doa, and Dob genes were 0.0295, 0.9705, 0.1159, and 0.8841 in 220 Chinese North Han, respectively. The Yta gene frequencies were 0.9928, 0.9917, and 0.9983 in 277 Han, 300 Hui, and 303 Tibetan blood donors, respectively. No Ok(a-) individuals were found in 304 Han, 300 Hui, and 303 Tibetan individuals.

Journal Article↗

PubMed2002

Spatial variation of plasma flow in the oxazolone-stimulated microcirculation.

INTRODUCTION: In cutaneous lymphocytic inflammation, enhanced regional blood flow is suggested by persistent erythema and warmth. Direct assessment of the microcirculation, however, has been limited by tissue edema and skin thickness. METHODS: To assess the microcirculatory adaptations to the epicutaneous antigen oxazolone, we studied the first pass kinetics and microvascular topography of the inflammatory skin microcirculation using a specially adapted epi-illumination intravital microscopy system. The fluorescence intravital videomicroscopy and streaming image acquisition of fluorescein-labeled dextran (approximately 500,000 MW) injections were used to assess changes in plasma flow. RESULTS: Direct plasma tracer injections of both the oxazolone-stimulated and control microcirculation demonstrated comparable transit times (leading edge and intensity-weighted peak times) from the carotid artery to the superficial vascular plexus (p > 0.05). In contrast to transit times, continuous infusion of the plasma tracer demonstrated a significant increase in the delivery of the fluorescein-labeled dextran to the oxazolone-stimulated microcirculation. Quantitative morphometry of intravital microscopic images demonstrated a 2.2-fold increase in the mean diameter of vessels in the superficial vascular plexus (p < 0.01). Further, fluorescence intensity mapping indicated that the increase was associated with increased perfusion of focal regions of the superficial vascular plexus (p < 0.001). CONCLUSIONS: These results indicate that the oxazolone-stimulated adaptations of the inflammatory microcirculation include both microvascular dilatation and the redistribution of plasma flow.

Animals↗

PubMed2002

Occurrence of Salmonella enterica serotype typhimurium DT104A in retail ground beef.

Surveillance data of cattle and human isolates of Salmonella enterica serovar Typhimurium DT104 indicate that this pathogen emerged worldwide in the 1980s, particularly in cattle. Studies were conducted to determine the prevalence of Salmonella Typhimurium DT104 in ground beef. Samples were also tested for the presence of generic Escherichia coli. A total of 404 fresh ground beef samples obtained at retail stores from New York, San Francisco, Philadelphia, Denver, Atlanta, Houston, and Chicago were shipped overnight to Georgia for processing. Salmonella spp. were isolated from 14 (3.5%) samples. Eight different serotypes were identified among the isolates, including Salmonella Typhimurium (5), Salmonella Lille (3), Salmonella Montevideo (1), Salmonella Hadar (1), Salmonella Meleagridis (1), Salmonella Cerro (1), Salmonella Kentucky (1), and Salmonella Muenster (1). Antibiotic resistance profiles indicated that all five Salmonella Typhimurium isolates were resistant to ampicillin, streptomycin, sulfamethoxazole, ticarcillin, and tetracycline but that they were sensitive to chloramphenicol. Phage typing revealed that all five Salmonella Typhimurium isolates were DT104A, a subtype of DT104. All five Salmonella Typhimurium DT104A isolates were obtained from ground beef sampled from retail outlets in San Francisco. Pulsed-field gel electrophoresis (PFGE) genomic DNA profiles of the five Salmonella Typhimurium DT104A isolates from ground beef were indistinguishable from those of four control Salmonella Typhimurium DT104 penta-resistant isolates from cattle that were used for comparison. A total of 102 generic E. coli isolates were obtained, only three of which were multiresistant to antibiotics. In addition, three E. coli isolates were recovered from samples that were positive for Salmonella Typhimurium DT104A. No correlation of antibiotic resistance profiles was observed between Salmonella Typhimurium DT104A and generic E. coli, as two of the three E. coli isolates were susceptible to all of the antibiotics tested, and the third isolate was resistant only to cephalothin. These data indicate that Salmonella Typhimurium DT104A can be isolated from retail ground beef, and because there was little overlap in antibiotic resistance patterns between Salmonella Typhimurium DT104A and E. coli isolates from the same ground beef samples, these limited data suggest that the transfer of antibiotic resistance genes among enteric bacteria in ground beef may not be common. This latter observation is further supported by the limited isolation of multiantibiotic-resistant E. coli from retail ground beef.

Animals↗

PubMed2001

[Preparation of decalcified bone matrix, bone cement and bone morphogenetic protein composite].

OBJECTIVE: To investigate the most excellent composite proportion and the most convenient composite method of decalcified bone matrix (DBM), bone cement (BC) and bovine bone morphogenetic protein (bBMP) composite. METHODS: The canine DBM and the bBMP were prepared beforehand. First mix the bBMP and DBM together with the proportion of 1:25 with adsorption and directly, then add BC with different weight proportion and finally the complex material was examined by biomechanics, scan electron microscope, determination of bone inductive activity and implanted into the canine femoral defect caused by microwave-induced hyperthermia. RESULTS: The bBMP had strong bone inductive activity and had no affect for this function when combined with DBM with different method. There were irregular gaps in the composite and most of them with diameter less than 100 microns and the porosity of the composite was less than 20% when the proportion of DBM was 40%. So it was unfavorable for the new bone to form and the new blood vessels to reconstruct. The DBM and BC could not be combined together when the proportion of DBM was 80%. While the biomechanical intensity of the composite decreased and the qualities of the new bone forming and new blood vessels reconstructing improved successively when the proportion of DBM was from 50% to 75%. CONCLUSION: It is the most convenient that bBMP is combined with DBM directly while its bone inductive activity could not be affected. The composite material not only has high biomechanical intensity, but also is favorable for new bone to form and new blood vessels to reconstruct when the proportion of DBM is 50% and 60%. So it is favorable for bone repair in the places where need to bear a load. However it is also favorable for bone repair in the places where do not need to bear a load when the proportion of DBM is 75%.

Animals↗

PubMed2001

HTLV-1 cell lines differ in constitutively activated signaling pathways that can be altered by cytokine exposure.

Examination of signaling pathways used by HTLV-1-infected rabbit cell lines revealed differences between one, RH/K30, that mediates asymptomatic infection and another, RH/K34, that causes lethal experimental leukemia. Both lines are IL-2 independent; RH/K30 produces IL-4 while RH/K34 produces IL-10. Examination of the Jak/STAT (Janus kinase/signal transducer and activator of transcription) activation of the lines revealed constitutive phosphorylation of Jak1 in both STAT6 phosphorylation, not previously reported for HTLV-1 cells, was observed in RH/K30; STAT1 and STAT3 were phosphorylated in RH/K34. Treatment with cytokines altered the activation of the STAT proteins: IL-2 induced STAT5 phosphorylation in both lines. Supernatant from RH/K34 or IL-10 induced STAT3 phosphorylation in RH/K30 cells. Supernatant from RH/K30 or IL-4 induced STAT6 phosphorylation in RH/K34 cells, which could be reversed with a Jak kinase inhibitor--AG-490.

Animals↗

PubMed2001

[A bivalent VP1 gene vaccine against Coxsackie virus B1/B3].

OBJECTIVE: To construct a bivalent VP1 gene vaccine against Coxsackie virus B1 and B3 (CVB1 and CVB3) and to test its immunogenicity in mice. METHODS: The VP1 gene of CVB1 was amplified by RT-PCR. The VP1 genes of CVB1 and of CVB3 under the control of cytomegalovirus (CMV) promoter and SV40 promoter respectively were inserted oppositely into the pCR3-Uni, a eukaryotic expression vector. The resultant bivalent gene vaccine plasmid was used to inoculate 3-week-old BALB/c mice. Immunofluorescence test and RT-PCR were conducted 24, 48, and 96 hours after the transfection. Sera of the tested animals were sampled at 0, 2, 4, and 6 weeks after the inoculation and detected for CVB-specific antibodies by ELISA. RESULTS: A bivalent gene vaccine plasmid of CVB1 and CVB3 was obtained. Samples of 4 and 6 weeks after the inoculation were shown to be CVB-antibody positive, while those of 0 and 2 weeks after the inoculation shown negative. CONCLUSION: The gene vaccine thus constructed induces CVB-speicific antibodies in mice, and can serve as gene vaccine candidate for human beings.

Animals↗

PubMed2001

Photophysical process of hexadecyl 4-biphenylamino benzoate.

The photophysical properties of hexadecyl 4-biphenylamino benzoate (HBAB), the molecule of which possesses a polar end composed of donor (triphenylamino group) and acceptor (ester group) and a long non-polar alkyl tail, have been carefully studied in different conditions. The results show that the twisted intramolecular charge transfer (TICT) emission is given in polar solvents at room temperature and intramolecular charge transfer (ICT) emission is given at 77 K. These can be supported by the solvent effect, temperature effect and the quenching process.

Acetates↗

PubMed2001

Integrin activation by regulated dimerization and oligomerization of platelet endothelial cell adhesion molecule (PECAM)-1 from within the cell.

Platelet endothelial cell adhesion molecule (PECAM)-1 is a 130-kD transmembrane glycoprotein having six Ig homology domains within its extracellular domain and an immunoreceptor tyrosine-based inhibitory motif within its cytoplasmic domain. Previous studies have shown that addition of bivalent anti-PECAM-1 mAbs to the surface of T cells, natural killer cells, neutrophils, or platelets result in increased cell adhesion to immobilized integrin ligands. However, the mechanism by which this occurs is not clear, and it is possible that anti-PECAM-1 mAbs elicit this effect by simply sequestering PECAM-1, via antibody-induced patching and capping, away from stimulatory receptors that it normally regulates. To determine whether dimerization or oligomerization of PECAM-1 directly initiates signal transduction pathways that affect integrin function in an antibody-independent manner, stable human embryonic kidney-293 cell lines were produced that expressed chimeric PECAM-1 cDNAs containing one or two FK506-binding protein (FKBP) domains at their COOH terminus. Controlled dimerization initiated by addition of the bivalent, membrane-permeable FKBP dimerizer, AP1510, nearly doubled homophilic binding capacity, whereas AP1510-induced oligomers favored cis PECAM-1/PECAM-1 associations within the plane of the plasma membrane at the expense of trans homophilic adhesion. Importantly, AP1510-induced oligomerization resulted in a marked increase in both adherence and spreading of PECAM/FKBP-2-transfected cells on immobilized fibronectin, a reaction that was mediated by the integrin alpha(5)beta(1). These data demonstrate that signals required for integrin activation can be elicited by clustering of PECAM-1 from inside the cell, and suggest that a dynamic equilibrium between PECAM-1 monomers, dimers, and oligomers may control cellular activation signals that influence the adhesive properties of vascular cells that express this novel member of the immunoreceptor tyrosine-based inhibitory motif family of regulatory receptors.

Cell Line↗

PubMed2001

A Cre-expressing cell line and an E1/E2a double-deleted virus for preparation of helper-dependent adenovirus vector.

Adenoviral vectors are attractive for the delivery of transgenes into mammalian cells because of their efficient transduction, high titer, and stability. The major concerns with using E1-deleted adenoviral vectors in gene therapy are the pathogenic potential of the virus backbone and the leaky viral protein synthesis that leads to host immune responses and a short duration of transgene expression. Helper-dependent (HD) adenoviral vectors that are devoid of all viral protein-coding sequences have significantly increased the safety and reduced the immunogenicity of these vectors. Currently available HD vectors depend on an E1-deleted adenovirus as a helper to provide viral proteins in trans. As a consequence, contamination with helper virus cannot be avoided in the HD vector preparation though it can be decreased to 0.01% using a Cre/loxP mechanism. Since the presence of E1-deleted helper virus may have substantial unwanted effects, we have developed a new Cre-expressing cell line based on an E1- and E2a-complementing cell. This new cell line can efficiently cleave the packaging region in the helper virus genome. We have also developed an E1 and E2a double-deleted helper virus. By using the CreE cell with the helper virus deleted in both the E1 and the E2a genes it may be possible to further improve the safety of the vectors.

Adenoviridae↗