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Jing Tian

Publications and source records attributed to Jing Tian.

At least 37 records · Page 2Linked to original sources
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

Mycobacterium tuberculosis appears to lack alpha-ketoglutarate dehydrogenase and encodes pyruvate dehydrogenase in widely separated genes.

Mycobacterium tuberculosis (Mtb) persists for prolonged periods in macrophages, where it must adapt to metabolic limitations and oxidative/nitrosative stress. However, little is known about Mtb's intermediary metabolism or antioxidant defences. We recently identified a peroxynitrite reductase-peroxidase complex in Mtb that included products of the genes sucB and lpd, which are annotated to encode the dihydrolipoamide succinyltransferase (E2) and lipoamide dehydrogenase (E3) components of alpha-ketoglutarate dehydrogenase (KDH). However, we could detect no KDH activity in Mtb lysates, nor could we reconstitute KDH by combining the recombinant proteins SucA (annotated as the E1 component of KDH), SucB and Lpd. We therefore renamed the sucB product dihydrolipoamide acyltransferase (DlaT). Mtb lysates contained pyruvate dehydrogenase (PDH) activity, which was lost when the dlaT gene (formerly, sucB) was disrupted. Purification of PDH from Mtb yielded AceE, annotated as an E1 component of PDH, along with DlaT and Lpd. Moreover, anti-DlaT antibody coimmunoprecipitated AceE. Finally, recombinant AceE, DlaT and Lpd, although encoded by genes that are widely separated on the chromosome, reconstituted PDH in vitro with Km values typical of bacterial PDH complexes. In sum, Mtb appears to lack KDH. Instead, DlaT and Lpd join with AceE to constitute PDH.

Acyltransferases↗
PubMed2005

HIV-Tat protein induces P-glycoprotein expression in brain microvascular endothelial cells.

Among the different factors which can contribute to CNS alterations associated with HIV infection, Tat protein is considered to play a critical role. Evidence indicates that Tat can contribute to brain vascular pathology through induction of endothelial cell activation. In the present study, we hypothesized that Tat can affect expression of P-glycoprotein (P-gp) in brain microvascular endothelial cells (BMEC). P-gp is an ATP-dependent cellular efflux transporter which is involved in the removal of specific non-polar molecules, including drugs used for highly active antiretroviral therapy (HAART). Treatment of BMEC with Tat(1-72) resulted in P-gp overexpression both at mRNA and protein levels. These alterations were confirmed in vivo in brain vessels of mice injected with Tat(1-72) into the hippocampus. Furthermore, pre-treatment of BMEC with SN50, a specific NF-kappaB inhibitor, protected against Tat(1-72)-stimulated expression of mdr1a gene, i.e. the gene which encodes for P-gp in rodents. Tat(1-72)-mediated changes in P-gp expression were correlated with increased rhodamine 123 efflux, indicating the up-regulation of transporter functions of P-gp. These results suggest that Tat-induced overexpression of P-gp in brain microvessels may have significant implications for the development of resistance to HAART and may be a contributing factor for low efficacy of HAART in the CNS.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2005

Scratching below the surface: wound healing and alanine mutagenesis provide unique insights into interactions between eristostatin, platelets and melanoma cells.

To study the molecular mechanism of the disintegrin eristostatin, cellular functional studies were performed using ten recombinant alanine mutants. ADP-induced platelet aggregation revealed critical contributions of seven residues within the 'RGD loop' (R24, R27, G28, N31) and C-terminus (W47, N48, G49) of this disintegrin. Using an in vitro scratch wound healing assay, four human melanoma cell lines yielded similar results when exposed to wildtype eristostatin. All eristostatin-treated cells healed less of the wounded area than control conditions. This phenomenon was reproduced when using fibronectin as the matrix. C8161 cells showed significant delay in wound closure with the N-terminal mutant P4A but not with R24A or G28A. Evidence from our laboratory and others suggests neither alpha IIb, alpha 4 nor alpha 5 integrins are directly involved in eristostatin's interactions. Eristostatin did not affect the number of melanoma cells in culture after 24 h or the development of apoptosis. However, phosphorylation studies performed after these melanoma cells were exposed to eristostatin revealed changes in several tyrosine phosphorylated molecules.

Alanine↗
PubMed2005

[Studies on the chemical constitutents in herb of Verbena officinalis].

OBJECTIVE: To isolate and identify the chemical constituents from Verbena officinalis. METHOD: The compounds were isolated by means of chromatography and the structures were determined on the basis of physical and spectral analysis. RESULT: Four compounds were isolated and identified as apigenin (I), 4'-hydroxywogonin (II), verbenalin (III) and hastatoside (IV). CONCLUSION: Compounds I and II were obtained from the genus for the first time.

Apigenin↗
PubMed2005

[Multidimensional separations used in pharmaceutical and biological fields].

A review of multidimensional separations such as comprehensive two-dimensional gas chromatography (GC x GC), comprehensive two-dimensional high performance liquid chromatography (HPLC x HPLC) and their applications in pharmaceutical and biological fields is presented with 71 references. A single CO2 cryo-jet loop modulator was developed for GC x GC and it can be used to modulate compounds higher than C6 effectively. Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC/TOF-MS) analyses of traditional Chinese medicine volatile oils such as Pogostemon cablin Benth (Cablin Patchouli), Forsythia suspensa (Thunb.) Vahl and Zedoary were reported also. As an emerging technology, multidimensional separations hold the promise and play an important role in the future pharmaceutical and biological fields.

Animals↗
PubMed2005

[Clinical research of plasma exchange with continuous veno-venous hemofiltration in treating mid- and late-stage chronic severe viral hepatitis B patients].

OBJECTIVE: To evaluate the clinical efficacy and study the mechanism of combining plasma exchange and continuous veno-venous hemofiltration in treating patients with chronic severe viral hepatitis B in their mid- and late stages. METHODS: 94 patients suffering from chronic severe viral hepatitis B were divided into three groups. 29 patients were treated with plasma exchange plus continuous veno-venous hemofiltration (group A). 31 patients were treated with plasma exchange alone (group B). 34 patients received routine treatment (group C). The efficacy of treatment and survival rate of the three groups was investigated. Before and after artificial liver support system treatment the levels of cytokine were examined. RESULTS: In group A, hyponatremia improved, the levels of interleukin 8 (IL-8) obviously decreased, the level of IL-10 increased, 5 of the 10 patients in coma regained normal consciousness (50.0%) and their survival rate was 48.3%. In group B, hyponatremia did not change, the level of IL-8 and IL-10 did not change. 2 of 11 patients in coma regained normal consciousness (18.2%) while survival rate was 22.6%. In group C, 1 of 11 patients in coma regained normal consciousness (9.1%) while survival rate was 20.6%. CONCLUSIONS: It shows that plasma exchange with continuous veno-venous hemofiltration in treating patients with mid- and late stage chronic severe viral hepatitis B can increase the survival rate. IL-8 can be significantly removed, IL-10 significantly increased. This combined therapy is easy to practice, and should be used as an artificial liver support system.

Adult↗
PubMed2005

[Applications and progresses of expert system on chromatography].

The expert system on chromatography has achieved great advancement in the past two decades, and is playing a more and more important role in solving analytical problems of complex samples. Research results of expert system on chromatography in authors' group are reviewed with 64 references. A brief introduction of the expert system on chromatography is presented. Applications of the expert system on chromatography are summarized in the fields of petrochemical online analysis, environmental air sample analysis, tumor diagnosis and traditional Chinese medicine analysis. The review followed the scientific foot steps in the authors' group, starting from the development of the expert system on gas chromatography, to the selection of multi-column systems in online industrial gas chromatographs in petrochemical plants, and to the employment of the new techniques in gas chromatography, liquid chromatography and capillary electrophoresis to solve the practical analytical problems in the nation's scientific and economic development.

Chromatography↗
PubMed2004

cDNA cloning and mRNA expression of a FTZ-F1 homologue from the pituitary of the orange-spotted grouper, epinephelus coioides.

A FTZ-F1 homologue was cloned from the pituitary cDNA library of the orange-spotted grouper. The full-length cDNA of the orange-spotted grouper FTZ-F1 spanned 1735 bp including a poly (A) tail. The open reading frame encodes a protein of 468 amino acids. Sequence analysis indicated that it had a structure typical of the orphan nuclear receptor superfamily, and the FTZ-F1 box, a characteristic of the FTZ-F1 family. Phylogenetic analysis indicated that the orange-spotted grouper FTZ-F1 was closely related to medaka FTZ-F1 and did not belong to either the SF-1/Ad4BP group or the LRH-1/FTF group. Virtual Northern Blot detected a major transcript of about 1.7 kb and a minor transcript of 2.2 kb of FTZ-F1 in the orange-spotted grouper pituitary gland. The expression of FTZ-F1 homologue gene in different tissues and during embryonic development of the orange-spotted grouper was determined using one-step RT-PCR coupled with Southern blot analysis. In addition to the pituitary gland, the orange-spotted grouper FTZ-F1 was also expressed in the hypothalamus, forebrain, heart, liver, kidney, and ovary. The stronger signal from the gel image indicated that the expression level of FTZ-F1 homologue gene was higher in the ovary of stage 3 than stage 2. During embryonic development, mRNA for the orange-spotted grouper FTZ-F1 homologue was present in newly fertilized eggs, but disappeared in embryos at 50 min post fertilization. The orange-spotted grouper FTZ-F1 homologue mRNA reappeared in embryos at 1.5 hr post fertilization. Its expression level was increased from late blastula to neurula stages. Taken together, results of the current study suggest that the orange-spotted grouper FTZ-F1 homologue exhibits characteristics indicative of both the LRH-1/FTF- and the SF-1/Ad4BP-like genes, and may also play important roles in the hypothalamus-pituitary-gonadal axis, cholesterol metabolism, and embryogenesis.

Amino Acid Sequence↗
PubMed2004

Two distinct cytochrome P450 aromatases in the orange-spotted grouper (Epinephelus coioides): cDNA cloning and differential mRNA expression.

The cDNA sequences encoding two distinct cytochrome P450 aromatases, namely P450aromB and P450aromA, were isolated from brain and ovary cDNA libraries of the orange-spotted grouper, respectively. The P450aromB cDNA consists of 1892 bp, and the open reading frame (ORF) encodes a putative protein of 506 amino acids. The P450aromA cDNA consists of 1836 bp, and the ORF encodes a putative protein of 518 amino acids. Northern blot analysis revealed a transcript of about 1.9 kb for P450aromB in the brain and kidney, and 2.1 kb for P450aromA in the ovary. The expression of both P450aromB and P450aromA genes in different tissues was further examined using one-step RT-PCR followed by Southern blot analysis. High levels of P450aromB mRNA expression were detected in the olfactory bulb, forebrain, midbrain, hypothalamus, medulla, pituitary, gill filament, gill arch, kidney, muscle, adipose tissue, and blood cells, but low levels in the hindbrain and ovary. High levels of P450aromA mRNA expression were detected in the ovary, pituitary, gill filament, gill arch, and spleen, but low levels in the forebrain, hindbrain, hypothalamus, and blood cells. In addition, the expression of P450arom genes in the orange-spotted grouper of different gonadal stages as induced by 17 alpha-methyltestosterone (MT) was investigated. The mRNA expression of P450aromB in the hypothalamus was highest in the intersexual stage, whereas the mRNA expression of P450aromA in the gonads was highest in the female stage, decreased in the intersexual stage, and lowest in the male stage. Results from current study indicate that P450aromB and P450aromA genes of the orange-spotted grouper have distinct tissue patterns of mRNA expression, and both of them may be involved in the MT-induced sex change.

Amino Acid Sequence↗
PubMed2004

cDNA sequence and spatio-temporal expression of prolactin in the orange-spotted grouper, Epinephelus coioides.

The cDNA sequence encoding the prolactin (PRL) gene of the orange-spotted grouper was obtained by randomly sequencing its pituitary cDNA library. The full-length cDNA of orange-spotted grouper PRL consists of 1342 bp. The open reading frame encodes a protein of 212 amino acids, which consists of a putative signal peptide of 24 residues and a mature protein of 188 amino acids. Northern blot analysis identified a single transcript of 1.4 kb in the pituitary gland, indicating perhaps the presence of only one form of PRL in the orange-spotted grouper. The expression of PRL gene in different tissues and during embryonic development of orange-spotted grouper was determined using one-step RT-PCR followed by Southern blot analysis. In addition to the pituitary gland, high levels of PRL gene expression were detected in the olfactory bulb, forebrain, midbrain, hypothalamus, hindbrain, medulla, gill, spleen, and adipose tissue. Very low levels of expression were detected in the kidney, liver, and blood cells. The PRL gene was also expressed in the gonads, with the higher level of expression observed in the stage 3 as compared to stage 2 ovary. During embryonic development, mRNA for PRL was detected at all time points examined except at 2h 15min post-fertilization, and its expression peaked at 9h post-fertilization, at the time of neurulation. Results from the current study suggest that PRL may have important paracrine or autocrine roles in diverse tissue types, including the brain and the gonads, and during embryonic development of the orange-spotted grouper.

Amino Acid Sequence↗
PubMed2004

[Allele frequencies and species specificity of six short tandem repeat loci in Chinese population].

OBJECTIVE: To develop a set of new markers for forensic application, the authors have chosen 6 short tandem repeat(STR) loci to study the allele frequencies and species specificity in Chinese Han population in Chengdu. METHODS: One hundred and ten EDTA-blood samples were collected from the unrelated individuals in Chengdu city, Sichuan province. DNA was extracted by Chelex-100 and amplified by the polymerase chain reaction(PCR). Polyacrylamide gel electrophoresis (PAGE) and silver staining were used to analyze the PCR products. RESULTS: The polymorphisms of all 6 STR loci have been obtained in Chinese Han population in Chengdu, the alleles of D4S2366, D4S2367, D6S474, D6S1281, D2S1396 and D20S601 being 7, 7, 6, 7, 5, 7, the observed heterozygosity of them being 0.802, 0.708, 0.770, 0.627, 0.542, 0.672, the discrimination power of them being 0.887, 0.828, 0.849, 0.848, 0.794, 0.865; and the power of exclusion of them being 0.602, 0.441, 0.544, 0.325, 0.227, 0.386. Evaluated by comparison with the data from 14 different animals as controls, the 6 STR loci contain good specificity of human beings. CONCLUSION: The 6 STR loci are highly polymorphic and can play a key role in species identification. They are new candidate markers for forensic personal identification and paternity testing.

Animals↗
PubMed2003

Effects of diazepam on closed- and open-loop optokinetic nystagmus (OKN) in humans.

The effects of diazepam on optokinetic nystagmus (OKN) eye movements were studied under closed-loop and open-loop conditions in healthy humans. The open-loop condition was achieved by adding the eye-movement velocity signal of OKN to the computer-generated signal controlling the moving stimulus grating. Each of four subjects received a single oral dose of 5 mg diazepam or a placebo on two separate days in a double-blind randomized fashion. OKN eye movements were measured 90 min after administration of the treatments. As compared to placebo, diazepam significantly reduced the gain of open-loop OKN, but did not modify the gain of closed-loop OKN. The results indicate that the OKN gain under the open-loop condition is a more sensitive detector of the parameter changes of the OKN system than under the closed-loop condition. Thus, open-loop OKN gain can provide an objective, quantitative measure of benzodiazepine agonist effects.

Adult↗
PubMed2003

[Effects of niflumic acid on the proliferation of human hepatoma cells].

The purpose of this work was to investigate the effects of niflumic acid (NFA), a chloride channel blocker, on the proliferation of human hepatoma cell line (HHCC). Cell proliferation was analyzed by cell count and MTT assay. Cell cycle analysis was carried out by flow cytometry. [Ca(2+)](i) was determined by laser scanning confocal system. It was found that NFA decreased significantly the cell number and the MTT optical density (OD) of HHCC cells, and that the OD value was reversed after washout of NFA. Compared with control, NFA blocked cell cycle progression in G(1) phase. Extracellular application of NFA (100 micromol/L) induced a rapid decrease in [Ca(2+)](i). These findings demonstrate that blockage of chloride channels by NFA induces growth arrest of HHCC in G(1) phase, which may be due to the inhibition of Ca(2+)/CaM-dependent signaling pathways.

Calcium↗
PubMed2003

HIV-1 Tat protein upregulates inflammatory mediators and induces monocyte invasion into the brain.

Impaired inflammatory functions may be critical factors in the mechanisms by which HIV-1 enters the CNS. Evidence indicates that a viral gene product, the protein Tat, can markedly contribute to these effects. In the present study we tested the hypothesis that Tat can upregulate the expression of inflammatory cytokines and adhesion molecules and facilitate the entry of monocytes into the brain. Expression of inflammatory mediators such as monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-alpha), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) was assessed in C57BL/6 mice injected with Tat(1-72) into the right hippocampus. In the Tat(1-72)-injected groups, mRNA and protein levels of MCP-1, TNF-alpha, VCAM-1, and ICAM-1 were markedly elevated compared to those in control animals. The most pronounced changes were observed in and around the injected hippocampus. Double-labeling immunohistochemistry demonstrated that inflammatory proteins were primarily expressed in activated microglial cells and perivascular cells. In addition, astrocytes and endothelial cells were susceptible to Tat(1-72)-induced inflammatory responses. These changes were associated with a substantial infiltration of monocytes into the brain. These data demonstrate that intracerebral administration of Tat can induce profound proinflammatory effects in the brain, leading to monocyte infiltration.

AIDS Dementia Complex↗
PubMed2003

Interocular motion combination for dichoptic moving stimuli.

When gratings moving in different directions are presented separately to the two eyes, we typically perceive periods of the combination of motion in the two eyes as well as periods of one or the other monocular motions. To investigate whether such interocular motion combination is determined by the intersection-of-constraints (IOC) or vector average mechanism, we recorded both optokinetic nystagmus eye movements (OKN) and perception during dichoptic presentation of moving gratings and random-dot patterns with various differences of interocular motion direction. For moving gratings, OKN alternately tracks not only the direction of the two monocular motions but also the direction of their combined motion. The OKN in the combined motion direction is highly correlated with the perceived direction of combined motion; its velocity complies with the IOC rule rather than the vector average of the dichoptic motion stimuli. For moving random-dot patterns, both OKN and perceived motion alternate only between the directions of the two monocular motions. These results suggest that interocular motion combination in dichoptic gratings is determined by the IOC and depends on their form.

Adult↗