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Biomedical subjects

Y Jiang

Publications and source records attributed to Y Jiang.

At least 343 records · Page 19Linked to original sources
PubMed1999

[Effects of temperature on the vasoconstrictive force of norepinephrine in rat aorta].

This study aimed at the influence of temperature on the vasoconstrictive effect of norepinephrine on rings of rat aorta and at the cause of the change observed. At the temperatures of 39.5 degrees C, 36.5 degrees C and 33.0 degrees C respectively, the vasoconstrictive force-time curve induced by norepinephrine and the equation of function were fitted. Statistical evaluation of the data was performed by F test. The difference was statistically significant (P < 0.01) among the three groups for relation constant X1 of function equation, but no significant difference (P > 0.05) was noted among the three groups for relation constant X2. Our experiments demonstrated that norepinephrine-induced vasoconstrictive force, in rat aorta, was obviously modulated by temperature. As the temperature of rat aorta was raised, the vasoconstrictive force and vasoconstrictive speed increased, and the effects of norepinephrine on vasculature were raised. The results suggest that the constant X1 for vasoconstrictive force is a factor sensitive to temperature.

Animals↗
PubMed1999

[Purification and characterization of alkaline xylanases from Pseudomonas G6-2].

Pseudomonas G6-2 produced two extracellular xylanases, named XynA and XynB. The enzymes were purified by ammonium sulfate fractionation, Sephadex G-100, DEAE-Sephadex, CM-Sephadex and Bio-gel P-10 chromatographies. Both enzymes were indicated to be endoxylanases, which produced oligomers of xylose from xylan and did not hydrolyze it to xylose. They had same temperature optimum(50 degrees C) and different pH optimum(pH 7.0-9.8 for XynA and pH 7.0-8.0 for XynB). At pH 7.6 and 65 degrees C, XynA and XynB possessed the half life of 6 min and 140 min, respectively. Their activities were strongly inhibited by Cu2+, Fe3+, Pb2+, Zn2+ and Hg2+. The results of chemical modification indicated that tryptophan and carboxy group were related to active center.

Endo-1,4-beta Xylanases↗
PubMed1999

[The isolation and characterization of type 1 pili from pathogenic Escherichia coli of chicken origin].

The pili from pathogenic Escherichia coli isolates 566, 1794 and TK3 of chicken and turkey origin were purified. After mechanic detachment from the bacterial cells, the pili were concentrated by precipitation with ammonium sulfate, dialyzed, and solubilized in buffer containing deoxycholate. The fraction containing the pilus was purified further by ultracentrifugation in a sucrose gradient. After ultracentrifugation, the pili at the density of 1.10 to 1.15 g.cm-3 (between 10%-20% of sucrose gradients) were collected, and the purified pili from strain 566, 1794 and TK3 had an apparent molecular weight of 17,500, 17,000 and 17,000 respectively, which retained their ability to bind the erythrocyte in a mannose-inhibitable fashion. Hyperimmunesera raised in BALB/C mice against the purified pili from strain 1794 reacted positively with type 1 pili from both isolates 566 and TK3 by immuno blot. These results revealed that the three strains either Chinese or north american isolates expressed type 1 pili which had molecular weights from 17,000 to 17,500, and they have common antigenic epitopes.

Animals↗
PubMed1999

[The implement of remote medical treatment by Internet & RAS].

This paper introduces a new method by taking full advantage of Internet and RAS technology, which can implement remote medical treatment perfectly. This method has been proved to be practical and will facilitate chinese hospital digital and information construction. The features and the advantages of of both technologies are introduced. Their designs & implement, and the prospect of this proposed method in china are discussed in details.

Hypermedia↗
PubMed1999

[The design and implement of PACS components in digital imaging apparatus].

The domestic application of PACS will surely be developed in the future, but it will still take a few years. This paper proposes a tradeoff scheme: Attaching to digital imaging apparatus the PACS components, which mainly contain the Auto-archiving unit, the Communication unit supporting WAN as well as LAN and the Converting Interface unit to the hospital PACS. In this way, a single digital imaging apparatus can archive and transmit data independently, also can merge with the hospital PACS conveniently in the future. In this paper, both the design and the implement are discussed in detail.

Angiography, Digital Subtraction↗
PubMed1999

Feasibility study of an ultrasound contrast agent (levovist) in color Doppler imaging of liver neoplasms.

The purpose of this study was to determine the efficacy of using an ultrasound contrast agent (levovist) to enhance the color Doppler imaging of liver neoplasms. Thirty patients with hepatic tumors were enrolled in this study. After intravenous administration of levovist, the color Doppler signals of normal hepatic vessels were enhanced. In various hepatic tumors, the different patterns of tumor vascularity were observed, which had not been demonstrated in conventional non-contrast color Doppler imaging. In 11 of 16 patients with hepatocarcinoma, additional color Doppler signals were observed in the central part of the tumors. On the contrary, 3 patients with metastatic liver lesions the enhanced color Doppler signals appear only at the peripheral of tumors. A typical rim-like color enhancement was seen in 2 of the 3 cases. In six patients with hepatic hemangiomas contrast-enhanced color Doppler imaging demonstrated the blood vessels at the margin of the neoplasms. Contrast-enhanced color Doppler imaging improves the visualization of the hepatic neoplasm vascularity. This technique holds great promise for detecting small liver tumors and differentiating hepatic neoplasms.

Adult↗
PubMed1999

[Studies on decomposed crop residues by FTIR differential analysis].

The decomposing process of corn leaf residues (CLR) was studied by FTIR differential analysis, and the differential spectra were compared with normal spectra. The result showed that the purification process to remove inorganic matters from decomposed CLR could be omitted when differential analysis is used, and the differential spectra were clear and distinct. As far as the studies of decomposed crop residues, the FTIR differential analysis was a convenient and forthright method.

Spectroscopy, Fourier Transform Infrared↗
PubMed1999

[The investigation of photoacoustic spectroscopy for polydiacetylene Langmuir-Blodgett films. (I) Structure characterization and photoacoustic absorption coefficient spectra].

The polydiacetylene (PAD) Langmuir-Blodgett (LB) films, which have potential applications in industry, were studied by using X-ray low angle diffraction and photoacoustic chopping frequency effects and photoacoustic absorption coefficients obtained. The X-ray low angle diffraction of PDA LB films prepared by different sequence of polymerization/transferring shows that the two kinds of PDA LB films have different array structures. The chopping frequency effects of PDA LB films of different thickness are consistent with Roscenwaig-Gersho theory and show that the thermal property of PDA LB films gradually becomes obvious with the increase of thickness. A new method of acquiring photoacoustic absorption coefficient from photoacoustic spectroscopy was also developed. The achievement of this paper shows that the PAS technique is a valid means for studying LB films.

English Abstract↗
PubMed1999

[Investigation of photoacoustic spectroscopy for polydiacetylene Langmuir-Blodgett films (II) synthetical analyse of the spectra and fluorescence quantum efficiency].

In this paper the polydiacetylene (PDA) Langmuir-Blodgett (LB) films, which have potential applications in industry, are studied by using photoacoustic spectrum (PAS) combined with optical absorption and fluorescence spectra. The synthetical analysis of PAS and optical absorption and fluorescence spectra for PDA LB films that underwent environment with different kinds of gases shows that the information about relaxation process of excitation state and feature of elementary excitation can be achieved. Besides, fluorescence quantum efficiency was discussed. The achievment of this paper shows that the PAS technique is a valid means for studying LB films and can capture information which cannot be achieved by other optical spectroscopy.

English Abstract↗
PubMed1998

Efficient transition to growth on fermentable carbon sources in Saccharomyces cerevisiae requires signaling through the Ras pathway.

Strains carrying ras2(318S) as their sole RAS gene fail to elicit a transient increase in cAMP levels following addition of glucose to starved cells but maintain normal steady-state levels of cAMP under a variety of growth conditions. Such strains show extended delays in resuming growth following transition from a quiescent state to glucose-containing growth media, either in emerging from stationary phase or following inoculation as spores onto fresh media. Otherwise, growth of such strains is indistinguishable from that of RAS2(+) strains. ras2(318S) strains also exhibit a delay in glucose-stimulated phosphorylation and turnover of fructose-1,6-bisphosphatase, a substrate of the cAMP-dependent protein kinase A (PKA) and a key component of the gluconeogenic branch of the glycolytic pathway. Finally Tpk(w) strains, which fail to modulate PKA in response to fluctuations in cAMP levels, show the same growth delay phenotypes, as do ras2(318S) strains. These observations indicate that the glucose-induced cAMP spike results in a transient activation of PKA, which is required for efficient transition of yeast cells from a quiescent state to resumption of rapid growth. This represents the first demonstration that yeast cells use the Ras pathway to transmit a signal to effect a biological change in response to an upstream stimulus.

Carbon↗
PubMed1998

Susceptibility alleles for aberrant B-1 cell proliferation involved in spontaneously occurring B-cell chronic lymphocytic leukemia in a model of New Zealand white mice.

B-cell chronic lymphocytic leukemia (B-CLL) and autoimmune disease are a related event, and genetic factors are linked to both diseases. As B-CLL is mainly of B-1 cell type that participates in autoantibody production, genetically-determined regulatory abnormalities in proliferation and/or differentiation of B-1 cells may determine their fate. We earlier found that, in H-2-congenic (NZB x NZW) F1 mice, while H-2(d/z) heterozygosity predisposes to autoimmune disease, H-2(z/z) homozygosity predisposes to B-CLL. Studies also suggested the involvement of non-H-2-linked NZW allele(s) in leukemogenesis. Using H-2-congenic NZW and B10 mouse strains, their F1 and backcross progeny, we have now identified three major NZW susceptibility loci for abnormal proliferation of B-1 cells, which form the basis of leukemogenesis; one H-2-linked locus on chromosome 17 and the other two non-H-2-linked loci, each on chromosome 13 and chromosome 17. Each susceptibility allele functioned independently, in an incomplete dominant fashion, the sum of effects determining the extent of aberrant B-1 cell frequencies. The development of leukemia was associated with age-related increase in B-1 cell frequencies in the blood. Thus, these alleles probably predispose B-1 cells to accumulate genetic alterations, giving rise to B-CLL. Potentially important candidate genes and correlation of the findings with autoimmune disease are discussed.

Animals↗
PubMed1998

Gene expression profiling of alveolar rhabdomyosarcoma with cDNA microarrays.

Several forms of human sarcoma, lymphoma, and leukemia are characterized by somatically acquired chromosome translocations that result in fusion genes that encode chimeric transcription factors with oncogenic properties. We have used cDNA microarrays containing 1238 cDNAs to investigate the gene expression profile of a group of seven alveolar rhabdomyosarcoma (ARMS) cell lines characterized by the presence of the PAX3-FKHR fusion gene. Using the method of multidimensional scaling to represent the relationships among the cell lines in two-dimensional Euclidean space, we determined that ARMS cells show a consistent pattern of gene expression, which allows the cells to be clustered together. By searching across the seven ARMS cell lines, we found that 37 of 1238 genes were most consistently expressed in ARMS relative to a reference cell line. Only three of these genes have been previously reported to be expressed in ARMS. Among these 37 were genes related to both primary (PAX3-FKHR) and secondary (CDK4) genetic alterations in ARMS. These results in ARMS demonstrate the potential of cDNA microarray technology to elucidate tumor-specific gene expression profiles in human cancers.

Chromosomes, Human, Pair 13↗
PubMed1998

Stat3 plays an important role in oncogenic Ros- and insulin-like growth factor I receptor-induced anchorage-independent growth.

The role of signal transducers and activators of transcription (STATs) in receptor protein-tyrosine kinase (PTK)-induced cell growth and transformation was investigated using an inducible epidermal growth factor receptor-Ros chimeric receptor called ER2 and a constitutively activated insulin-like growth factor I receptor called NM1, both of which are able to induce anchorage-independent growth of NIH 3T3 cells. ER2 and NM1 receptor PTKs are able to cause Stat3 activation. Co-expressing the dominant negative Stat3 mutant with ER2 or NM1 in transiently or stable transfected cells resulted in a dramatic inhibition of colonies induced by these receptor PTKs and a moderate inhibition of their mitogenicity in monolayer. Therefore, Stat3 is not only important for initiation of transformation, as demonstrated by inhibition of the epidermal growth factor-inducible colony formation of the ER2 cells by the mutant, but it is also required for the maintenance of transformation, as evidenced by reversion of the NM1 transformed cells. The DNA binding and transcriptional activities of the endogenous Stat3 were greatly inhibited in the ER2 and NM1 cells co-expressing the Stat3 mutants. We conclude that activated function of Stat3 is required for the establishment and maintenance of Ros and insulin-like growth factor I receptor PTK-induced cell transformation.

3T3 Cells↗
PubMed1998

The G protein G alpha12 stimulates Bruton's tyrosine kinase and a rasGAP through a conserved PH/BM domain.

Heterotrimeric guanine-nucleotide-binding proteins (G proteins) are signal transducers that relay messages from many receptors on the cell surface to modulate various cellular processes. The direct downstream effectors of G proteins consist of the signalling molecules that are activated by their physical interactions with a G alpha or Gbetagamma subunit. Effectors that interact directly with G alpha12 G proteins have yet to be identified. Here we show that G alpha12 binds directly to, and stimulates the activity of, Bruton's tyrosine kinase (Btk) and a Ras GTPase-activating protein, Gap1m, in vitro and in vivo. G alpha12 interacts with a conserved domain, composed of the pleckstrin-homology domain and the adjacent Btk motif, that is present in both Btk and Gap1m. Our results are, to our knowledge, the first to identify direct effectors for G alpha12 and to show that there is a direct link between heterotrimeric and monomeric G proteins.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1998

[Identification of a mutation hotspot in exon 8 of Wilson's disease gene by cycle sequencing].

OBJECTIVE: To screen for mutation hotspot of Wilson's disease (WD) gene in Chinese. METHODS: Cycle sequencing was used to detect mutation in exon 8 of WD gene in 30 patients with WD. RESULTS: The same missense mutation, Arg778Leu, was identified in 14 WD patients, four of which were homozygous and the others were heterozygous for this mutation. The frequency of this mutation was 30%. CONCLUSION: The codon 778(CGG-->CTG) of exon 8 in WD gene was one of mutation hotspots in Chinese.

Adolescent↗
PubMed1998

Activation of caspase-1 in the nucleus requires nuclear translocation of pro-caspase-1 mediated by its prodomain.

The interleukin-1beta-converting enzyme-like protease precursor, pro-caspase-1, has an N-terminal prodomain that is removed during cleavage activation of the protease. Here we show that tumor necrosis factor treatment of HeLa cells induced apoptosis without detectable proteolytic activation of caspase-1 in the cytosol. Instead, tumor necrosis factor induced the translocation of pro-caspase-1 to the nucleus where it was proteolytically activated, releasing the intact prodomain. We identified a nuclear localization signal in the prodomain, which was required for translocation of both pro-caspase-1 as well as its prodomain to the nucleus. Surprisingly, transfected MCF-7 carcinoma or embryonic kidney 293T cells expressing the prodomain alone underwent apoptosis. These results show that death signal-induced nuclear targeting is a novel activity of a caspase prodomain and indicate that caspase-1 and its prodomain may have hitherto unsuspected nuclear functions in apoptosis.

Amino Acid Sequence↗
PubMed1998

Role for neuronally derived fractalkine in mediating interactions between neurons and CX3CR1-expressing microglia.

A recently identified chemokine, fractalkine, is a member of the chemokine gene family, which consists principally of secreted, proinflammatory molecules. Fractalkine is distinguished structurally by the presence of a CX3C motif as well as transmembrane spanning and mucin-like domains and shows atypical constitutive expression in a number of nonhematopoietic tissues, including brain. We undertook an extensive characterization of this chemokine and its receptor CX3CR1 in the brain to gain insights into use of chemokine-dependent systems in the central nervous system. Expression of fractalkine in rat brain was found to be widespread and localized principally to neurons. Recombinant rat CX3CR1, as expressed in Chinese hamster ovary cells, specifically bound fractalkine and signaled in the presence of either membrane-anchored or soluble forms of fractalkine protein. Fractalkine stimulated chemotaxis and elevated intracellular calcium levels of microglia; these responses were blocked by anti-CX3CR1 antibodies. After facial motor nerve axotomy, dramatic changes in the levels of CX3CR1 and fractalkine in the facial nucleus were evident. These included increases in the number and perineuronal location of CX3CR1-expressing microglia, decreased levels of motor neuron-expressed fractalkine mRNA, and an alteration in the forms of fractalkine protein expressed. These data describe mechanisms of cellular communication between neurons and microglia, involving fractalkine and CX3CR1, which occur in both normal and pathological states of the central nervous system.

Amino Acid Sequence↗