PubMed Health⌕ Search

Biomedical subjects

D Ye

Publications and source records attributed to D Ye.

At least 37 records · Page 2Linked to original sources
PubMed2000

Nitroblue tetrazolium blocks BK channels in cerebrovascular smooth muscle cell membranes.

The effects of p-nitroblue tetrazolium (NBT) on large conductance, calcium-activated potassium channels (BK channels) in enzymatically dispersed rat cerebrovascular smooth muscle cells (CVSMCs) were examined. Patch clamp methods were employed to record single BK channel currents from inside-out patches of CVMC membrane maintained at 21 - 23 degrees C. When applied to the cytoplasmic face of inside-out membrane patches (internally applied NBT), micromolar concentrations of NBT reversible reduced the mean open time of BK channels, without changing channel conductance. NBT altered the frequency distribution of BK channel open times from a two exponential to a single exponential form. In the absence of NBT, mean channel open time increased on membrane depolarization. In the presence of internally applied NBT, mean channel open became essentially independent of membrane potential. Internally applied NBT also reduced the mean closed time of BK channels when measured at membrane potentials in the range -80 mV to +20 mV. The combined effects of internal NBT on mean open and closed times resulted in the suppression of BK channel open probability when measured at positive membrane potentials. When applied to the external membrane face, micromolar concentrations of NBT reduced mean channel open time progressively as the membrane was hyperpolarized, and also reduced open probability at negative membrane potentials. A model is proposed in which NBT alters channel gating by binding to a site at or near to the cytoplasmic membrane face. Externally applied NBT suppressed BK channel open probability at concentrations which also inhibit nitric oxide synthase (NOS). Therefore, the potential role of potassium channel block in NBT actions previously attributed to NOS inhibition is discussed.

Animals↗
PubMed2000

Mutational analysis of the Helicobacter pylori vacuolating toxin amino terminus: identification of amino acids essential for cellular vacuolation.

The functional importance of the amino terminus of the Helicobacter pylori vacuolating cytotoxin (VacA) was investigated by analyzing the relative levels of vacuolation of HeLa cells transfected with plasmids encoding wild-type and mutant forms of the toxin. Notably, VacA's intracellular activity was found to be sensitive to small truncations and internal deletions at the toxin's amino terminus. Moreover, alanine-scanning mutagenesis revealed the first VacA point mutations (at proline 9 or glycine 14) that completely abolish the toxin's intracellular activity.

Bacterial Proteins↗
PubMed2000

Characterization of a novel porcine endothelin(B) receptor splice variant.

Screening of porcine cerebellum cDNA library with porcine endothelin(B) (ET(B)) receptor cDNA revealed a novel ET(B) receptor cDNA that is distinctly different from the wild-type ET(B) receptor in length and the amino acid sequence at the C-terminal end. This sequence appears to represent alternate splicing of the carboxy terminal end of ET(B) receptor, resulting in a polypeptide of 429 amino acids in length, which is 14 amino acids shorter than the wild-type porcine ET(B) receptor. Characterization of the wild-type and alternately spliced ET(B) receptors expressed in COS cells revealed that both receptors displayed very similar binding [apparent dissociation constant (K(d)) and maximum binding (B(max)) for (125)I-ET-1 were 71 pM and 1.6 pmol/mg protein for wild-type and 81 pM and 1.2 pmol/mg protein for splice variant ET(B) receptors] as well as functional properties. These data suggest that the differences in the amino acids at the C-terminal end had no effect on binding or functional coupling of these alternately spliced ET(B) receptors.

Alternative Splicing↗
PubMed2000

A telemedicine management model based on message-trigger service.

A telemedicine system model, based on a message-trigger service, is described. This model distributes system applications on multiple computers and establishes a communication platform to exchange messages among all applications. By broadcasting event messages, an application is able to trigger a set of local and remote services. At the same time, a protocol for message exchange is proposed to fulfill cooperation of applications. To validate the model, a teleconsultation system is designed. The results indicate that the model has good compatibility and that the characteristics are easy to implement.

Computer Communication Networks↗
PubMed2000

[The correlation of cytokines TNF alpha, IFN-gamma, Epo with anemia in rheumatoid arthritis].

OBJECTIVE: To elucidate the characteristics of anemia of chronic disease(ACD) in rheumatoid arthritis(RA), and the role of TNF alpha, IFN-gamma and Epo in the pathogenesis of ACD. METHOD: Serum TNF alpha and IFN-gamma levels in RA patients and serum Epo levels in RA with ACD were measured by ELISA. Serum iron status profile in RA patients were also detected. The effects of TNF alpha and IFN-gamma on cobalt-induced erythropoietin production in human hepatic cancer cells(HepG2) were examined. The effect of TNF alpha and IFN-gamma erythroid colony formation (CFU-E and BFU-E) of normal bone marrow cells, and the effect of serum from RA patients and Epo on CFU-E yields of RA bone marrow cells. RESULT: Serum TNF alpha or IFN-gamma in RA and RA with ACD patients were higher than those in normal controls, and were inversely correlated with hemoglobin, and serum iron levels. Serum Epo levels in ACD patients were lower than those in iron-deficiency anemia patients with comparable hemoglobin level. TNF alpha and IFN-gamma could specifically inhibit cobalt-induced Epo production in HepG2 cells, and suppressed normal bone marrow BFU-E and CFU-E growth in a dose-dependent manner. Bone marrow CFU-E yields of RA patients were also suppressed by their own serum. The inhibitory effects of TNF alpha, IFN-gamma or serum from RA patients on erythroid colony formation could be corrected by the addition of rhEpo. CONCLUSION: It suggested that there were hematopoietic inhibiting factors in the serum of RA patients. TNF alpha or IFN-gamma was involved in the pathogenesis of anemia in RA patients. Administration of rhEpo might be beneficial for anemia of RA patients.

Adolescent↗
PubMed2000

[Studies on 5 kinds of methods combination for detection of smear and culture negative pulmonary tuberculosis].

OBJECTIVE: To evaluate the diagnostic value of 5 kinds of methods used jointly for smear and culture negative pulmonary tuberculosis. METHODS: The high specificity methods were PCR examination for sputum TB-DNA, immunological examination (ELISA method) for serum LAM IgG, PPD IgG, SCIC and PPD 0.1 U skin test. Smear and culture positive cases were 31, smear and culture negative 54, healthy control 53, other lung disease 30. Methods were used for every case synchronously, then the sensitivity and specificity of single method and the diagnostic value of single and joint examination for smear and culture negative patients were evaluated. RESULTS: In single examination sensitivity of PCR, LAM IgG, PPD IgG, SCIC, PPD 0.1 U was 96.8%, 69.2%, 62.1%, 32.0%, 53.8% respectively; specificity was 96.2%, 98.1%, 98.1%, 98.1% correspondingly. The positive detection rate of single examination for sputum TB negative patients was just 21.4%-44.4%. In combination examination the positive rates increased remarkblely by the number combined from 2 to 5, they were 66.9%, 70.5%, 80.4%, 85.7% respectively and they were more notable than that of TB positive group. The specificity of combination examination was slightly decreased by the number combined. It decreased just by 9% and the specificity of most examination methods kept on no less than 90%. CONCLUSIONS: For diagnosis of smear and culture negative pulmonary tuberculosis combination examination using the high specificity methods can increase the sensitivity obviously and the specificity just decrease slightly. It is valuable for widely use of combination method in detection of smear and culture negative patients.

Adolescent↗
PubMed2000

[Experimental study on effect of Shenmai injection in improving contractility of fatigue diaphragm in rats].

OBJECTIVE: To study and compare the effects of Shenmai Injection (SMI) and aminophylline on pathogenesis and developing process of diaphragmatic fatigue. METHODS: SMI group, aminophylline group, SMI plus aminophylline group and control group of isolated rat's diaphragmatic muscular strip of equal length were set up, and electric stimulation was applied. Changes of related parameters in the fatigue inducing and recovery process were estimated. RESULTS: During fatigue inducing process, the lowering on maximal rates of relaxation (dR/dtmax) was earlier than that on maximal contraction peak (Pt) and contraction rate (dT/dtmax), and restoring of these parameters were restored later and incompletely. SMI could prolong the time Pt needed for reducing 50%, speed up the restoration of Pt. Although aminophylline could increase Pt, it shortened the fatigue inducing time and postponed the recovery. CONCLUSION: Disturbance in the function of relaxation plays important role in diaphragm fatigue induction. Through strengthening the capability to relax, SMI could improve the function of fatigue diaphragm. Aminophylline would damage the relaxation function together with the increasing contraction of diaphragm simultaneously, and this side-effect could be antagonised partly by SMI.

Aminophylline↗
PubMed1999

A dominant negative mutant of Helicobacter pylori vacuolating toxin (VacA) inhibits VacA-induced cell vacuolation.

Most Helicobacter pylori strains secrete a toxin (VacA) that causes structural and functional alterations in epithelial cells and is thought to play an important role in the pathogenesis of H. pylori-associated gastroduodenal diseases. The amino acid sequence, ultrastructural morphology, and cellular effects of VacA are unrelated to those of any other known bacterial protein toxin, and the VacA mechanism of action remains poorly understood. To analyze the functional role of a unique strongly hydrophobic region near the VacA amino terminus, we constructed an H. pylori strain that produced a mutant VacA protein (VacA-(Delta6-27)) in which this hydrophobic segment was deleted. VacA-(Delta6-27) was secreted by H. pylori, oligomerized properly, and formed two-dimensional lipid-bound crystals with structural features that were indistinguishable from those of wild-type VacA. However, VacA-(Delta6-27) formed ion-conductive channels in planar lipid bilayers significantly more slowly than did wild-type VacA, and the mutant channels were less anion-selective. Mixtures of wild-type VacA and VacA-(Delta6-27) formed membrane channels with properties intermediate between those formed by either isolated species. VacA-(Delta6-27) did not exhibit any detectable defects in binding or uptake by HeLa cells, but this mutant toxin failed to induce cell vacuolation. Moreover, when an equimolar mixture of purified VacA-(Delta6-27) and purified wild-type VacA were added simultaneously to HeLa cells, the mutant toxin exhibited a dominant negative effect, completely inhibiting the vacuolating activity of wild-type VacA. A dominant negative effect also was observed when HeLa cells were co-transfected with plasmids encoding wild-type and mutant toxins. We propose a model in which the dominant negative effects of VacA-(Delta6-27) result from protein-protein interactions between the mutant and wild-type VacA proteins, thereby resulting in the formation of mixed oligomers with defective functional activity.

Amino Acid Sequence↗
PubMed1999

Gene expression from the ORF50/K8 region of Kaposi's sarcoma-associated herpesvirus.

The ORF50 gene of Kaposi's sarcoma (KS)-associated herpesvirus, or human herpesvirus 8 (KSHV), activates viral replication and is weakly homologous to the herpesvirus family of R transactivators; therefore, the transcription and translation events from this region of KSHV are key events in viral reactivation. We demonstrate that ORF50 is expressed in a bicistronic message after induction of the viral lytic cycle. ORF50 migrated as a series of polypeptides: the major ones as 119 and 101 kDa, respectively. Using 3' rapid amplification of cDNA ends, RT-PCR, and cDNA library screening, we demonstrate that the major ORF50 transcript also encodes K8. The ORF50/K8 transcript was resistant to cyclohexamide, whereas the K8 transcript was only partially resistant to cyclohexamide at early timepoints. Both transcripts showed partial resistance after 12 h of phorbol ester induction. Using a GAL4-ORF50 fusion protein expression vector, we demonstrate that the transactivation domain of ORF50 resides within a 160-amino-acid region of the carboxyl portion of the ORF. Upstream regions of both ORF50 and K8 have basal promoter activity in KSHV-infected cells. K8, which had sequence homology to Bzip proteins, did not activate either promoter. However, both promoters were activated after cotransfection of ORF50 in BCBL-1 cells.

Alternative Splicing↗
PubMed1999

The SPOROCYTELESS gene of Arabidopsis is required for initiation of sporogenesis and encodes a novel nuclear protein.

The formation of haploid spores marks the initiation of the gametophytic phase of the life cycle of all vascular plants ranging from ferns to angiosperms. In angiosperms, this process is initiated by the differentiation of a subset of floral cells into sporocytes, which then undergo meiotic divisions to form microspores and megaspores. Currently, there is little information available regarding the genes and proteins that regulate this key step in plant reproduction. We report here the identification of a mutation, SPOROCYTELESS (SPL), which blocks sporocyte formation in Arabidopsis thaliana. Analysis of the SPL mutation suggests that development of the anther walls and the tapetum and microsporocyte formation are tightly coupled, and that nucellar development may be dependent on megasporocyte formation. Molecular cloning of the SPL gene showed that it encodes a novel nuclear protein related to MADS box transcription factors and that it is expressed during microsporogenesis and megasporogenesis. These data suggest that the SPL gene product is a transcriptional regulator of sporocyte development in Arabidopsis.

Amino Acid Sequence↗
PubMed1999

Identification of the minimal intracellular vacuolating domain of the Helicobacter pylori vacuolating toxin.

Helicobacter pylori secretes a cytotoxin (VacA) that induces the formation of large vacuoles originating from late endocytic vesicles in sensitive mammalian cells. Although evidence is accumulating that VacA is an A-B toxin, distinct A and B fragments have not been identified. To localize the putative catalytic A-fragment, we transfected HeLa cells with plasmids encoding truncated forms of VacA fused to green fluorescence protein. By analyzing truncated VacA fragments for intracellular vacuolating activity, we reduced the minimal functional domain to the amino-terminal 422 residues of VacA, which is less than one-half of the full-length protein (953 amino acids). VacA is frequently isolated as a proteolytically nicked protein of two fragments that remain noncovalently associated and retain vacuolating activity. Neither the amino-terminal 311 residue fragment (p33) nor the carboxyl-terminal 642 residue fragment (p70) of proteolytically nicked VacA are able to induce cellular vacuolation by themselves. However, co-transfection of HeLa cells with separate plasmids expressing both p33 and p70 resulted in vacuolated cells. Further analysis revealed that a minimal fragment comprising just residues 312-478 functionally complemented p33. Collectively, our results suggest a novel molecular architecture for VacA, with cytosolic localization of both fragments of nicked toxin required to mediate intracellular vacuolating activity.

Anti-Bacterial Agents↗
PubMed1999

Augmentation of a humanized anti-HER2 mAb 4D5 induced growth inhibition by a human-mouse chimeric anti-EGF receptor mAb C225.

Overexpression of epidermal growth factor (EGF) receptor and HER2 (p185neu) may both contribute to the growth of human cancers. A humanized anti-HER2 monoclonal antibody (mAb) 4D5 and a human-mouse chimeric anti-EGF receptor mAb C225 are currently being investigated in clinical trials for their anti-tumor activities. In the present study, we have examined the effect of concurrent treatment of OVCA 420 human ovarian cancer cells with mAb C225 and mAb 4D5. Exposure of OVCA420 cells to saturating concentrations of C225 (20 nM) for 7 days resulted in 40-50% growth inhibition, and exposure to 20 nM mAb 4D5 also resulted in 30-40% growth inhibition. The growth inhibition of OVCA420 cells by mAb C225 or 4D5 was associated with an increased G1 cell population; an increased level of a cyclin-dependent kinase (CDK) inhibitor p27Kip1 with increased association of p27kip1 with CDK2, CDK4 and CDK6; and decreased activities of these CDKs. Combination treatment with concurrent exposure to mAbs C225 and 4D5 resulted in additive anti-proliferative effects on these cells, which was accompanied by enhanced G1 cell distribution, a greater increase in the levels of p27Kip1 and a greater decrease in the activities of CDK kinases. The anti-proliferative effects and related changes in cell cycle regulators induced by mAb 4D5, mAb C225 or the combination of the two mAbs could be reversed by concurrent exposure to exogenous EGF. Our data suggest the potential fruitful cooperation of anti-EGF receptor mAb and anti-HER2 mAb in the treatment of human cancers stimulated by EGF receptor and HER2 signals.

Animals↗
PubMed1999

Analysis of flanking sequences from dissociation insertion lines: a database for reverse genetics in Arabidopsis.

We have generated Dissociation (Ds) element insertions throughout the Arabidopsis genome as a means of random mutagenesis. Here, we present the molecular analysis of genomic sequences that flank the Ds insertions of 931 independent transposant lines. Flanking sequences from 511 lines proved to be identical or homologous to DNA or protein sequences in public databases, and disruptions within known or putative genes were indicated for 354 lines. Because a significant portion (45%) of the insertions occurred within sequences defined by GenBank BAC and P1 clones, we were able to assess the distribution of Ds insertions throughout the genome. We discovered a significant preference for Ds transposition to the regions adjacent to nucleolus organizer regions on chromosomes 2 and 4. Otherwise, the mapped insertions appeared to be evenly dispersed throughout the genome. For any given gene, insertions preferentially occurred at the 5' end, although disruption was clearly possible at any intragenic position. The insertion sites of >500 lines that could be characterized by reference to public databases are presented in a tabular format at http://www.plantcell. org/cgi/content/full/11/12/2263/DC1. This database should be of value to researchers using reverse genetics approaches to determine gene function.

Arabidopsis↗
PubMed1999

2-Bromoethanesulfonate, sulfate, molybdate, and ethanesulfonate inhibit anaerobic dechlorination of polychlorobiphenyls by pasteurized microorganisms

Dechlorination of Aroclor 1242 by pasteurized microorganisms was inhibited by 2-bromoethanesulfonate (BES), sulfate, molybdate, and ethanesulfonate. Consumption of these anions and production of sulfide from BES were detected. The inhibition could not be relieved by hydrogen. Taken together these results suggest that pattern M dechlorination is mediated by spore-forming sulfidogenic bacteria. These results also suggest that BES may inhibit anaerobic dechlorination by nonmethanogens by more than one mechanism.

Journal Article↗
PubMed1999

Androgen and epidermal growth factor down-regulate cyclin-dependent kinase inhibitor p27Kip1 and costimulate proliferation of MDA PCa 2a and MDA PCa 2b prostate cancer cells.

Low levels of p27Kip1 in primary prostate cancer specimens have been shown to be associated with higher rates of disease recurrence and poor rates of disease-free survival in patients with localized disease. In this study, we provide the first direct evidence showing that dihydrotestosterone (DHT), a major proliferation regulator of prostate cancer, can down-regulate p27Kip1 and stimulate cyclin-dependent kinase-2 (CDK2) activity in established prostate cancer cell lines. We investigated the cooperative effects of DHT and epidermal growth factor (EGF) on the proliferation of androgen-responsive MDA PCa 2a and MDA PCa 2b prostate cancer cells. DHT and EGF each stimulated proliferation of these cells, but exposure of the cells to DHT and EGF together stimulated greater proliferation. Stimulation of cell proliferation by DHT and/or EGF was associated with increased CDK2 activity and a decreased level of p27Kip1. There seems to be a positive feedback stimulation loop between androgen-induced gene transcription and EGF-stimulated signal transduction, as one could stimulate the synthesis of the receptors for the other. Dual blockade of androgen receptor function with the antiandrogen hydroxyflutamide and EGF receptor superfamily-mediated signal transduction with the anti-EGF receptor monoclonal antibody C225 and the anti-HER2 receptor monoclonal antibody Herceptin significantly enhanced growth inhibition of the MDA PCa 2a cells. Our results demonstrate the importance of counteracting both androgen receptors and EGF receptors in the development of novel therapies for prostate cancer.

Androgen Antagonists↗
PubMed1999

[The comparison of component contents and pharmacological actions between two kinds of processed products of Pinellia rhizoma prepared by ginger juice and alum].

OBJECTIVE: To compare the component contents in Pinellia Rhizoma processed with ginger separately on orthogonal technology and pharmaceutical technology stipulated in pharmacopoeia, and study the action of the two differently processed products on animals. METHOD: Using gravimetric method and acid dye colorimetry to determine the total alkaloids, et al. RESULT AND CONCLUSION: The experiment has shown that the contents of total alkaloids of product of Pinellia Rhizoma processed by orthogonal technology are higher than those processed by pharmaceutical technology, but the contents of digged substances of the latter are higher than those of the former, and the toxicity of decoction of the latter is also higher than that of the former. Compared with raw Pinellia Rhizoma, the two products of Pinellia Rhizoma prepared by different technologies all have shown promoting action on PGE2 contents and activity of gastric proteinase in rat gastric juice. The experimental results also have shown that on the above mentioned items. There are no obvious differences between the product of Pinellia Rhizoma processed by orthogonal technology and the product processed by pharmaceutical technology. However, the component contents of raw Pinellia Rhizoma are lower than those of the above mentioned two processed products and help inhibit PGE2 contents and activity of gastric proteinase in rat gastric juice.

Alkaloids↗
PubMed1998

N-ras mutations in 43 Chinese cases of acute myeloid leukemia.

OBJECTIVE: To detect 3 kinds of N-ras mutations in Chinese patients with acute myeloid leukemia (AML). METHODS: In vitro DNA amplification followed by oligonucleotide dot analysis were used to study N-ras gene mutations in 43 cases of acute myeloid leukemia (AML). 25 healthy people were used as controls. Patients were selected in the Beijing district and consisted of 19 males and 24 females. The average age was 37. The controls were healthy individuals with the average age of 36.5 from the same region. 3 oligonucleotide probes were artificially synthesized to detect mutations in codon 12 and 13 of N-ras. RESULTS: Five out of 43 AML samples have been found contain G-->A mutation in codon 12.2 have G-->T mutation in codon 12. One has G-->A mutation in codon 13. The mutation rate was 18.6%. None of the controls presented these mutations. The frequency of mutation of N-ras in the AML samples showed statistical differences with that of the controls. CONCLUSION: Analysis of the results suggests the N-ras mutations may have some relationship with the etiology of acute myeloid leukemia.

Adult↗