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Biomedical subjects

Jun Yang

Publications and source records attributed to Jun Yang.

At least 181 records · Page 10Linked to original sources
PubMed2005

A new mitochondrial RNA deletion fragment accelerated by oxidative stress in rat L6 cells.

RNA deletions may be easier to detect and more extensive than DNA deletions. Two large deletion fragments (1120 and 7811 bp) of mitochondrial RNA were observed in rat L6 muscle cells. At the site of the 1120 bp deletion, the remaining RNA fragment was re-linked by a short additional section (GGTATGAAGCT). These kinds of deletions were accelerated by oxidative stress and were not observed in mitochondrial DNA.

Animals↗
PubMed2005

Use of an artificial neural network to localize accessory pathways of Wolff-Parkinson-White syndrome with 12-lead electrocardiogram.

Today, radio-frequency ablation has been shown to be a safe and effective method to treat paroxysmal tachycardia with Wolff-Parkinson-White syndrome. The many criteria reported for localizing the sites of accessory pathways from a 12-lead electrocardiogram have not proven adequate to differentiate the correct sites of accessory pathways for all situations. This study trained an artificial neural network to differentiate the varied features needed to localize 10 sites of accessory pathways. One hundred fifty patients underwent successful catheter ablation, with manifest single and antegradely conducting accessory pathways. Using the two electrocardiogram features of polarity of delta wave and R wave's share of QRS complex, an artificial neural network learned the characteristics of electrocardiogram waves for each site of the 10 accessory pathways through 90 learning cases, and an applicable network model was developed for testing. In 58 of 60 test cases (96.7%), sites of accessory pathways were localized correctly by the network. Based on the method employed in the present study, it thus becomes possible to predict the sites of accessory pathways with Wolff-Parkinson-White syndrome in more detail by using an artificial neural network with a 12-lead electrocardiogram. In the future, when this method is incorporated into a conventional automatic electrocardiogram system which could analyze delta waves and ORS complex, it will become useful to automatically diagnose the locations of the accessory pathways with Wolff-Parkinson-White syndrome in clinical practice.

Adolescent↗
PubMed2005

Transcutaneous fluorescence dilution cardiac output and circulating blood volume during hemorrhagic hypovolemia.

BACKGROUND: Cardiac output and circulating blood volume are important parameters for assessing cardiac function in the intensive care setting and during major surgeries. The authors tested in an animal model of hemorrhagic hypovolemia the feasibility of measuring these parameters simultaneously by transcutaneous fluorescence monitoring of an intravenous bolus injection of indocyanine green. METHODS: Fluorescence dilution cardiac output was measured in seven anesthetized rabbits and compared to thermodilution cardiac output. The optical probe used to excite the indocyanine green fluorescence was in contact with the skin above the ear artery. Local heating enhanced blood perfusion of the measurement site. Cardiac output was measured during baseline conditions, during hemorrhagic hypovolemia, and after partial restoration of the blood volume with reinfused blood. Estimates of the circulating blood volume were simultaneously obtained from the analysis of the fluorescence dilution traces. RESULTS: Cardiac output measured by fluorescence dilution (thermodilution) averaged 455 +/- 16 (450 +/- 13) ml/min in baseline conditions and 323 +/- 15 (330 +/- 13) ml/min during hypovolemia. Fluorescence dilution cardiac output was linearly related to thermodilution cardiac output (slope = 1.13 +/- 0.05, ordinate = -50 +/- 19 ml/min, R = 0.92). Interanimal differences explained most of the variance between cardiac output estimates obtained with the two techniques. Circulating blood volume decreased from 204 +/- 5 ml in baseline conditions to 174 +/- 8 ml after bleeding and reflected blood volume changes in this acute bleeding-reinfusion model. CONCLUSIONS: The study extends the applicability of the fluorescence dilution technique for cardiac output measurement to hypovolemic conditions and demonstrates its ability to produce accurate estimates of the circulating blood volume in experimental animals.

Algorithms↗
PubMed2005

Floral patterning in Lotus japonicus.

Floral patterning in Papilionoideae plants, such as pea (Pisum sativum) and Medicago truncatula, is unique in terms of floral organ number, arrangement, and initiation timing as compared to other well-studied eudicots. To investigate the molecular mechanisms involved in the floral patterning in legumes, we have analyzed two mutants, proliferating floral meristem and proliferating floral organ-2 (pfo-2), obtained by ethyl methanesulfonate mutagenesis of Lotus japonicus. These two mutants showed similar phenotypes, with indeterminate floral structures and altered floral organ identities. We have demonstrated that loss of function of LjLFY and LjUFO/Pfo is likely to be responsible for these mutant phenotypes, respectively. To dissect the regulatory network controlling the floral patterning, we cloned homologs of the ABC function genes, which control floral organ identity in Arabidopsis (Arabidopsis thaliana). We found that some of the B and C function genes were duplicated. RNA in situ hybridization showed that the C function genes were expressed transiently in the carpel, continuously in stamens, and showed complementarity with the A function genes in the heterogeneous whorl. In proliferating floral meristem and pfo-2 mutants, all B function genes were down-regulated and the expression patterns of the A and C function genes were drastically altered. We conclude that LjLFY and LjUFO/Pfo are required for the activation of B function genes and function together in the recruitment and determination of petals and stamens. Our findings suggest that gene duplication, change in expression pattern, gain or loss of functional domains, and alteration of key gene functions all contribute to the divergence of floral patterning in L. japonicus.

Amino Acid Sequence↗
PubMed2005

Modeling of finite-amplitude sound beams: second order fields generated by a parametric loudspeaker.

The nonlinear interaction of sound waves in air has been applied to sound reproduction for audio applications. A directional audible sound can be generated by amplitude-modulating the ultrasound carrier with an audio signal, then transmitting it from a parametric loudspeaker. This brings the need of a computationally efficient model to describe the propagation of finite-amplitude sound beams for the system design and optimization. A quasilinear analytical solution capable of fast numerical evaluation is presented for the second-order fields of the sum-, difference-frequency and second harmonic components. It is based on a virtual-complex-source approach, wherein the source field is treated as an aggregation of a set of complex virtual sources located in complex distance, then the corresponding fundamental sound field is reduced to the computation of sums of simple functions by exploiting the integrability of Gaussian functions. By this result, the five-dimensional integral expressions for the second-order sound fields are simplified to one-dimensional integrals. Furthermore, a substantial analytical reduction to sums of single integrals also is derived for an arbitrary source distribution when the basis functions are expressible as a sum of products of trigonometric functions. The validity of the proposed method is confirmed by a comparison of numerical results with experimental data previously published for the rectangular ultrasonic transducer.

Acoustics↗
PubMed2005

Allo-specific T-cells encoding for viral IL-10 exert strong immunomodulatory effects in vitro but fail to prevent graft rejection.

Recently, we demonstrated the capacity of allo-specific gene-engineered T lymphocytes as transport vehicle for therapeutic transgenes into allografts. In this study, the influence of viral IL-10 as therapeutic transgene was addressed. Lewis rat T-cell lines specific for DA rat alloantigens were engineered to express vIL-10 by using a retroviral gene expression system. Like T regulatory 1 cells, vIL-10 transgenic T lymphocytes express the phenotype CD4(+)25(+) and secrete, in addition to vIL-10, rat IL-10 and IFN-gamma but no IL-4. First, the capacity of vIL-10 transgenic T-cell lines to modulate alloantigen-specific immune responses was evaluated in vitro. In comparison to control MLR with no transgenic cells or equal numbers of control T(EGFP)-lymphocytes, the proliferation as well as production of IFN-gamma by naive responder cells were significantly diminished. Despite this regulatory capacity in vitro, T(vIL-10)-lymphocytes were not able, either alone or in combination with suboptimal doses of Cyclosporine A, to prolong the survival of either DA rat cardiac or renal allografts in Lewis rat recipients. These data demonstrate that intra-graft IL-10 over-expression is not sufficient to prolong allograft survival in a high-responder strain combination and that the regulatory capacity of T cells in vitro does not predict their in vivo efficiency.

Animals↗
PubMed2005

A lipidomic study of the effects of N-methyl-N'-nitro-N-nitrosoguanidine on sphingomyelin metabolism.

Systems biology is a new and rapidly developing research area in which, by quantitatively describing the interaction among all the individual components of a cell, a systems-level understanding of a biological response can be achieved. Therefore, it requires high-throughput measurement technologies for biological molecules, such as genomic and proteomic approaches for DNA/RNA and protein, respectively. Recently, a new concept, lipidomics, which utilizes the mass spectrometry (MS) method for lipid analysis, has been proposed. Using this lipidomic approach, the effects of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on sphingomyelin metabolism, a major class of sphingolipids, were evaluated. Sphingomyelin molecules were extracted from cells and analyzed by matrix-assisted laser desorption ionization-time of flight MS. It was found that MNNG induced profound changes in sphingomyelin metabolism, including the appearance of some new sphingomyelin species and the disappearance of some others, and the concentrations of several sphingomyelin species also changed. This was accompanied by the redistribution of acid sphingomyelinase (ASM), a key player in sphingomyelin metabolism. On the other hand, imipramine, an inhibitor of ASM, caused the accumulation of sphingomyelin. It also prevented some of the effects of MNNG, as well as the redistribution of ASM. Taken together, these data suggested that the lipidomic approach is highly effective for the systematic analysis of cellular lipids metabolism.

Amnion↗
PubMed2005

The ciliary rootlet maintains long-term stability of sensory cilia.

The striated ciliary rootlet is a prominent cytoskeleton originating from basal bodies of ciliated cells. Although a familiar structure in cell biology, its function has remained unresolved. In this study, we carried out targeted disruption in mice of the gene for rootletin, a component of the rootlet. In the mutant, ciliated cells are devoid of rootlets. Phototransduction and ciliary beating in sensory and motile cilia initially exhibit no apparent functional deficits. However, photoreceptors degenerate over time, and mutant lungs appear prone to pathological changes consistent with insufficient mucociliary clearance. Further analyses revealed a striking fragility at the ciliary base in photoreceptors lacking rootlets. In vitro assays suggest that the rootlet is among the least dynamic of all cytoskeletons and interacts with actin filaments. Thus, a primary function of the rootlet is to provide structural support for the cilium. Inasmuch as photoreceptors elaborate an exceptionally enlarged sensory cilium, they are especially dependent on the rootlet for structural integrity and long-term survival.

Animals↗
PubMed2005

Electrokinetic power generation by means of streaming potentials: a mobile-ion-drain method to increase the streaming potentials.

We show, by natural occurring phenomena of charge separation near the solid-liquid interface in microchannels, that electricity can be generated by forcing water through a ceramic rod with no moving part and emission. A single hand push on a syringe is our source of power which easily generates a streaming potential of over 20 V and a streaming current of 30 microA. By means of streaming potentials, two capacitors were charged and discharged alternatively to light-up two Light-Emitting-Diodes in every ten seconds. From our specific choice of liquid/solid pair, an efficiency of 0.8% was obtained. A mobile-ion-drain method is also demonstrated to increase the streaming potential.

Electric Conductivity↗
PubMed2005

Endocytic delivery of lipocalin-siderophore-iron complex rescues the kidney from ischemia-reperfusion injury.

Neutrophil gelatinase-associated lipocalin (Ngal), also known as siderocalin, forms a complex with iron-binding siderophores (Ngal:siderophore:Fe). This complex converts renal progenitors into epithelial tubules. In this study, we tested the hypothesis that Ngal:siderophore:Fe protects adult kidney epithelial cells or accelerates their recovery from damage. Using a mouse model of severe renal failure, ischemia-reperfusion injury, we show that a single dose of Ngal (10 microg), introduced during the initial phase of the disease, dramatically protects the kidney and mitigates azotemia. Ngal activity depends on delivery of the protein and its siderophore to the proximal tubule. Iron must also be delivered, since blockade of the siderophore with gallium inhibits the rescue from ischemia. The Ngal:siderophore:Fe complex upregulates heme oxygenase-1, a protective enzyme, preserves proximal tubule N-cadherin, and inhibits cell death. Because mouse urine contains an Ngal-dependent siderophore-like activity, endogenous Ngal might also play a protective role. Indeed, Ngal is highly accumulated in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. We reveal what we believe to be a novel pathway of iron traffic that is activated in human and mouse renal diseases, and it provides a unique method for their treatment.

Acute-Phase Proteins↗
PubMed2005

In vivo quantitative assessment of catheter patency in rats.

Formation of fibrin sleeves around catheter tips is a central factor in catheter failure during chronic implantation, and such tissue growth can occur despite administration of anticoagulants. We developed a novel method for monitoring catheter patency. This method recognizes the progressive nature of catheter occlusion, and tracks this process over time through measurement of changes in catheter resistance to a standardized 1 mL bolus infusion from a pressurized reservoir. Two indirect measures of catheter patency were used: (a) reservoir residual pressure and (b) reservoir discharge time. This method was applied to the study of catheter patency in rats comparing the effect of catheter material (silastic, polyurethane, Microrenathanetrade mark), lock solution (heparin, heparin/dexamethasone) and two different cannulation sites (superior vena cava via the external jugular vein, inferior vena cava via the femoral vein). Our findings reveal that application of flexible smaller-size silastic catheters and a dexamethasone lock solution resulted in prolonged catheter patency. Patency could be maintained over nine weeks with the femoral vein catheters, compared with five weeks with the external jugular vein catheters. The current method for measuring catheter patency provides a useful index for the assessment of tissue growth around the catheter tip. The method also provides an objective and quantitative way of comparing changes in catheter patency for different surgical methods and catheter types. Our method improves on the conventional method of assessing catheter occlusion by judging the ability to aspirate from the catheter.

Analysis of Variance↗
PubMed2005

Analysis of ESTs and gene expression patterns of the posterior silkgland in the fifth instar larvae of silkworm, Bombyx mori L.

The fibroin gene expression pattern and regulation of the posterior silkgland were studied by means of expressed sequence tags (ESTs) using the first and fifth day larvae of the fifth instar of silkworm, Bombyx mori L (strain: C 108). The results showed that there were 911 repetitive ESTs and 1950 single sequences (Singlets) among total 2861 consentient sequences, which were spliced. 1335 sequences were identified and the other 1526 were unknown. 5560 sequences (55.89%) in the posterior silkgland cell of the silkworm were new ESTs without homology with EST data published by Mita et al. The number of repetitive ESTs and single sequences from the first day larvae of the fifth instar was double more than that of the fifth day of the same instar in the silkworms. The unigenes which were more than 50 in repetitive EST size (contig size) came to only about 0.5% in total consentient sequences. There were significant differences between gene expression frequencies, and expressed genes were related to fibroin synthesis and its secretion and fibroin composition. Comparing the fifth day with the first day of the fifth instar, the genes-expressed quantity of fibroin heavy-chain gene was 18 fold higher, fibroin light-chain gene 9 fold and fibroin P52 gene 8 fold. 508 genes functioned for cellular component and 315 for enzyme after function tracing. These results implied that the gene expression of the first day was mainly for preparation for fibroin synthesis except for the growth of silkgland cells, and the gene expression of the fifth day of the fifth instar was mainly for synthesizing and excreting fibroin. Because the ratio of heavy chain, light chain and p25 of fibroin was not 6:6:1 as theoretically expected, or its special H-chain structure, the H-chain gene was not easy to detect through EST technique. Most of genes among total 2861 consentient sequences functioned for fibroin synthesis and secretion. This suggested the fibroin synthesis and secretion procedure of the posterior silkgland was more complex than the knowledge we have.

Animals↗
PubMed2005

Research of blastocyte-like structure in chicken.

The chicken embryo is a classic model used to investigate embryonic development, gene expression, and tissue differentiation, and is also an important research tool in studying the animal functional genomics. The whole blastoderms of fresh unincubated eggs from White Leghorn chickens were collected with a paper ring, mechanically broken into small pieces and cultured in medium. Then the small pieces would develop into blastocyte-like structures (BLS), which could be facilitated by an addition of fetal bovine serum (FBS) to the primary culture and their diameter was nearly doubled from 12 to 24 h. The additional yolk had no positive effect on the development in the first 12 h but encouraged the BLSs attaching and inner cells differentiating instead in 24 h. The inner cells of the BLS showing a high alkaline-phosphatase activity similar to those in mouse embryonic stem (ES) cells and also expressing a large amount of the specific stage embryonic antigen-1 (SSEA-1) on the surface, which was known to be the characteristic of non-differentiated mouse and avian ES cells, could finally differentiate into nerve-like cells, fibroblast cells and so on in the medium. Leukemia inhibitory factor (LIF) facilitated the cells' proliferation and prevented differentiation in the suspended culture of the BLSs. So we drew the conclusion that the BLS obtained from broken blastoderm can be used to amplify avian ES cells so as to initiate a new method of producing transgenic chickens.

Animals↗
PubMed2005

[FK506 promotes apoptosis of macrophages activated by homogenate of allogenic nerve].

OBJECTIVE: To study the effect of FK506 in promoting apoptosis of peripheral blood-derived macrophages activated by homogenate of allogenic nerve tissues. METHODS: Homogenate of the allogenic nerve tissues was prepared using the sciatic nerve and injected in one-month-old SD rats, from which the macrophages activated by the homogenate were collected from the abdominal cavity and cultured in vitro. The cells were divided into 4 groups according to different concentrations of FK506 for treatment, namely 0 (group A, control group), 0.25 ng/ml (group B), 0.5 ng/ml (group C), and 1.0 ng/ml (group D). The cells of the 4 groups were inoculated into 96-well plate respectively for detecting the viability of the macrophages by MTT assay and for morphological evaluation of the cell apoptosis by transmission electron microscopy and fluorescence microscopy. RESULTS: The cells in groups B and C exhibited reduced viability and signs of apoptosis, and necrosis was observed in group D. Transmission electron microscopy and fluorescence microscopy identified early apoptotic changes and the presence of apoptotic body in the macrophages. The apoptotic rates of groups B and C were much higher than that in group A found by flow cytometry. CONCLUSION: FK506 can promote the apoptosis of macrophage activated by allogenic nerve homogenate and reduce macrophage-mediated immunological rejection of peripheral nerve allograft.

Animals↗
PubMed2005

LT(K63/R72), a new mutant of Escherichia coli heat-labile enterotoxin, exhibits characteristics more similar to LT(K63) than LT(R72).

LT(K63), a non-toxic mutant and LT(R72), a low toxic mutant of E. coli heat-labile enterotoxin are frequently used mucosal adjuvants. In many cases, the adjuvanticity of LT(K63) is lower than that of LT(R72), but LT(K63), which induces a mixed Th1/Th2 response, exhibits a higher level of protection than LT(R72) which induces a polarized Th2-type response. To utilize the advantages of both adjuvants, a double-mutation LT(K63/R72) was generated and purified. The characterization results showed that there was no significant difference in production rate and immunogenicity between wild type LT and LT mutants. The results also showed that the toxicity and the trypsin sensitivity of LT(K63/R72) are between that of LT(K63) and LT(R72). Using HPLC, when samples in an OHpak SB-800 column were eluted by denatural buffer (TEAN containing 10 mg/ml SDS), we found the stability of LT(K63/R72) was higher than that of LT(R72) and lower than that of LT(K63). Through further analyzes, we found that LT(K63/R72) exhibits characteristics more closely related to LT(K63) than LT(R72).

Animals↗
PubMed2005

[Screening of human scFv against IL-8 from phage antibody library].

AIM: To screen human scFv against IL-8 from phage antibody library. METHODS: IL-8-His fusion protein was expressed in E.coli BL21 (DE3) transfected with prokaryotic expression vector pRSET-IL-8 and was purified by affinity chromatography. Specific antibody was screened by 3 rounds of panning of phage antibody library with the fusion protein. The antigen binding activity and DNA sequences of positive clones were determined and analyzed. RESULTS: After 3 rounds of panning, 2 positive clones were obtained which could bind IL-8 specifically. DNA sequence analysis showed both of the 2 VH genes belonged to human IgG VH3 subgroup, and the Vlambda gene belonged to human VlambdaDPL5 and VlambdaDPL2 subgroups,respectively. CONCLUSION: It is feasible to obtain human anti-IL-8 antibody by phage display technique, which provides the basis for further research on psoriasis and other related diseases.

Antibodies↗