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X Y Yang

Publications and source records attributed to X Y Yang.

At least 55 records · Page 3Linked to original sources
PubMed1997

Linkage analysis using platelet-activating factor Ca2+ response in transformed lymphoblasts.

Epstein-Barr virus-transformed lymphoblasts from patients with essential hypertension demonstrate enhanced G protein-mediated cytosolic free calcium ([Ca2+]i) response to platelet-activating factor (PAF). To map genes responsible for variation in G protein-coupled signaling, we used this cellular phenotype for a linkage study of transformed cell lines from the Centre d'Etude du Polymorphisme Humain (CEPH) reference pedigrees. The PAF-evoked change in [Ca2+]i ranged from 20 to 392 mmol/L and was highly reproducible within each cell line. PAF-elicited [Ca2+]i responses were obtained in lymphoblastic cell lines from five densely mapped pedigrees of the CEPH collection. Using PAF-evoked [Ca2+]i responses as a quantitative trait, two-point sibpair linkage analyses were conducted using 5150 markers from the Collaborative Human Linkage Center (CHLC) database. Nine loci, located on chromosomes 1, 4, 10, 11, 13, 16, and 17, were suggestive of linkage, with values of P < 7.4 x 10(-4). Multipoint linkage analysis produced a significant linkage finding (P = 2.1 x 10(-5) in one family at D16S151, with suggestive linkage results for seven additional markers spanning a 40-cM interval of chromosome 16. Multipoint analysis produced suggestive findings of linkage to eight loci from two distinct regions of chromosome 11 in another family. These results indicate that loci involved in the control of G protein-mediated mechanisms, suggested to be involved in the pathophysiology of essential hypertension, can be identified using cell lines from general pedigrees selected without any knowledge of the blood pressure status of the donors. This strategy represents an approach to rapidly and inexpensively mapping loci related to common, complex disorders, using phenotypes that are stable in immortalized lymphoblasts together with existing reference pedigree cell lines and genotype databases.

B-Lymphocyte Subsets↗
PubMed1996

Redox regulation of GA-binding protein-alpha DNA binding activity.

We have investigated the reduction/oxidation (redox) regulation of the heteromeric transcription factor GA-binding protein (GABP). GABP, also known as nuclear respiratory factor 2, regulates the expression of nuclear encoded mitochondrial proteins involved in oxidative phosphorylation, including cytochrome c oxidase subunits IV and Vb, as well as the expression of mitochondrial transcription factor 1. GABP is composed of two subunits, the Ets-related GABP-alpha, which mediates specific DNA binding, and GABP-beta, which forms heterodimers and heterotetramers on DNA sequences containing the PEA3/Ets motif ((C/A)GGA(A/T)(G/A)). We demonstrate here that GABP DNA binding activity and GABP-dependent gene expression in 3T3 cells are inhibited by pro-oxidant conditions. DNA binding of recombinant GABP-alpha was activated by chemical reduction (dithiothreitol) and by thioredoxin; however, GSSG inhibited GABP DNA binding activity. Treatment of GABP-alpha, but not GABP-beta1, with sulfhydryl-alkylating agents also inhibited GABP DNA binding activity. Our results suggest that GABP DNA binding activity is redox-regulated in vivo, possibly by thioredoxin-mediated reduction and by GSSG-mediated oxidation of the GABP-alpha subunit. The regulation of GABP (nuclear respiratory factor 2) DNA binding activity by cellular redox changes provides an important link between mitochondrial and nuclear gene expression and the redox state of the cell.

3T3 Cells↗
PubMed1996

Effect of ganglioside GM3 on the activity and conformation of reconstituted Ca2+-ATPase.

Trace amounts of gangliosides were found in rabbit skeletal muscle sarcoplasmic reticulum and their main part was shown, by high performance thin layer chromatography. to be GM3. Addition of GM3 to the soybean phospholipids used for reconstitution of proteoliposomes markedly increased ATP hydrolysis as well as Ca2+ uptake activity of sarcoplasmic reticulum Ca2+-ATPase incorporated into the proteoliposomes. Conformation changes of Ca2+-ATPase induced by GM3 were also observed by intrinsic fluorescence and circular dichroism measurements.

Adenosine Triphosphate↗
PubMed1996

Isolation and characterization of a folate receptor-directed metalloprotease from human placenta.

Glycosyl-phosphatidylinositol-anchored hydrophobic placental folate receptors (PFRs), which have an important functional role in maternal-to-fetal transplacental folate transport, can be converted to soluble hydrophilic forms by a placental metalloprotease. Using a Triton X-114 temperature-induced phase separation assay to monitor enzyme-mediated conversion of radiolabeled hydrophobic PFR into hydrophilic PFR, a metalloenzyme was isolated to apparent homogeneity from Triton X-114-solubilized human placenta using concanavalin A-Sepharose and reverse-phase high performance liquid chromatography (HPLC) as major purification steps. The purified hydrophobic enzyme eluted as a single protein peak on reverse-phase HPLC and SDS-polyacrylamide gel electrophoresis revealed a single 63,000 M(r) species, which was reduced to 58,000 M(r) following deglycosylation, findings comparable with amino acid analysis (M(r) approximately 59,000). The metalloenzyme was activated by Mg2+, Zn2+, Mn2+, and Ca2+, optimally at physiologic pH; it also exhibited EDTA-sensitive endoproteolytic cleavage of [3H]leucine-labeled full-length nascent PFR polypeptide generated in vitro in the absence of microsomes. Rabbit polyclonal anti-metalloprotease antiserum specifically immunoprecipitated 125I-metalloprotease and recognized cross-reacting moieties on plasma membranes of normal human hematopoietic progenitor cells and human cervical carcinoma cells, both of which also express FR.

Amino Acids↗
PubMed1996

Effect of transmembrane Ca2+ gradient on the coupling of beta-adrenergic receptors and adenylyl cyclase.

In order to investigate the effect of transmembrane Ca2+ gradient on Gs mediated coupling of beta-AR and adenylyl cyclase, beta-AR from duck erythrocytes and Gs and adenylyl cyclase from bovine brain cortices were co-reconstituted into asolectin liposomes with different transmembrane Ca2+ gradient. These proteoliposomes were proven to be impermeable to water-soluble substances. The results obtained indicate that a physiological transmembrane Ca2+ gradient (1000-fold) is essential for higher stimulation of adenylyl cyclase by hormone-activated beta-AR via coupling to Gs and can be further enhanced by the decrease of such Ca2+ gradient within certain range (100 fold) following Ca2+ influx into cells during signal transduction. Fluorescence polarization of DPH revealed that transmembrane Ca2+ gradient modulates adenylyl cyclase and its stimulation by hormones through mediating a change in lipid fluidity. Correspondent conformational changes of beta-AR were also detected from the fluorescence spectra and quenching of Acrylodan-labelled beta-AR in those proteoliposomes. It is suggested that a proper transmembrane Ca2+ gradient is essential for the optimal fluidity of the phospholipid bilayer in the proteoliposomes, which favors the formation of a suitable conformation of the reconstituted beta-AR and thus promotes the stimulation of adenylyl cyclase activities by hormone-activated beta-AR via Gs.

Adenylyl Cyclases↗
PubMed1996

[The trend of proportion among inpatients with gout in 21 hospitals during the past 15 years].

We analyzed data gathered from 21 hospitals in our country from 1979 to 1993 on the total number of hospitalized patients with the number of gout patients. Results showed that the proportion of hospitalized gout patients in 21 hospitals has increased sharply during the past 15 years (Chi2 = 823.4, P < 0.001). The constituent ratio of hospitalized gout patients in 13 hospitals in southern China increased abruptly (Chi2 = 650.9, P < 0.001); while the constituent ratio in 8 hospitals in northern China increased to a lesser extent (Chi2 = 188.1, P < 0.001). A significant difference was noticed between southern and northern China (Chi2 = 45.8, P < 0.001). During the past 15 years, the proportion of hospitalized gout patients has been increasing rapidly, with greater extent in the south. This is probably related to the economic development which improves the standard of living and to the changes of food structure.

China↗
PubMed1995

The endothelin receptor profile in L6 myotubes.

In this study we characterized the endothelin (ET) receptors of cultured L6 myotubes in order to gain a further insight into the mechanism of the ET effect on skeletal muscle cells. Displacements of 125I-ET-1 by unlabeled ET-1, ET-2 and ET-3 revealed receptors with a high affinity (Kd < 1 nmol/l) to ET-1 and ET-2 and a low affinity (Kd > 100 nmol/l) to ET-3, which suggested the presence of primarily ETA receptors on L6 myotubes. These findings were complemented by displacement binding kinetics, in which the ETA receptor antagonist JKC-301 was used. More-over, the ET-1-evoked increase in the cytosolic free Ca was blocked by JKC-301 but not by the ETB receptor antagonist IRL-1038. Collectively, these findings indicate that the ET-mediated response in cultured skeletal muscle cells is through the ETA receptor.

Calcium↗
PubMed1995

[Determination of beta-phenyllactic acid in rat plasma by derivatization capillary gas chromatography (DCGC)].

The determination of beta-phenyllactic acid (PLA) in rat plasma by derivatization capillary gas chromatography is described. Quantitation was affected by 63Ni-electron capture detector after separation with a SE-54 quartz capillary chromatographic column. Calibration curves were linear within the range of 1.6-9.6 micrograms.ml-1. The limit of detection of PLA was considered to be 0.5 microgram.ml-1. PLA was extracted from plasma with ethyl acetate (rat plasma 0.1 ml). The recovery from plasma was high and the mean value was 98.11 +/- 3.81 (s)%, their within day and between day relative standard deviations were 5.13% and 5.99% respectively.

Animals↗
PubMed1995

Pharmacokinetics of ceftizoxime in renal failure patients without dialysis.

AIM: To investigate the pharmacokinetics of ceftizoxime (Cef) in renal failure patients without any dialysis and supply the basis for a suitable clinical regimen. METHODS: Cef in plasma and urine was assayed by HPLC. RESULTS: After injecting Cef 16.7 mg kg-1, Cef concentration in blood was described as a 2-compartment open model. The main pharmacokinetic parameters were Vd 0.55 +/- 0.17 L kg-1; AUC 879 +/- 460 mg L-1 h; Cl 27 +/- 11 mL kg-1 h-1. T1/2 beta was 15 +/- 4 h. CONCLUSION: T1/2 beta in renal failure patients was about 10 times longer than that in normal volunteers. The clinical regimen should be adjusted in renal failure patients with infection, either prolonging the interval between Cef administration, or decreasing Cef dosage.

Ceftizoxime↗
PubMed1994

Endothelin mobilizes calcium and enhances glucose uptake in cultured human skeletal myoblasts and L6 myotubes.

In this study we used endothelin as a paradigm to explore the concept that some vasoactive agents, acting through mobilization of Ca2+ and stimulation of protein kinase C, can interact with human skeletal muscle and modify its glucose transport. Cultured human skeletal myoblasts from the vastus lateralis demonstrated two subclasses of high-affinity endothelin receptors and a robust increase in cytosolic free Ca2+ upon exposure to endothelin. The endothelin-evoked rise in cytosolic free Ca2+ primarily resulted from Ca2+ mobilization from intracellular organelles. Both endothelin and insulin enhanced [3H]deoxy-D-glucose uptake in human myoblasts, but their effects were not additive. These findings also were observed in differentiated myotubes of L6 skeletal muscle cells. Moreover, [3H]deoxy-D-glucose uptake in human myoblasts was enhanced by treatment with phorbol 12-myristate 13-acetate. The endothelin- and insulin-mediated increases in [3H]deoxy-D-glucose were totally ablated by treatment with calphostin C. Such observations suggest that endothelin can enhance glucose uptake in human skeletal muscle. This is mediated through mechanisms that are at least partially protein kinase C dependent. Thus, increased levels of endothelin in vascular beds may contribute to altered glucose metabolism in essential hypertension.

Animals↗
PubMed1994

[A clinical study on low dose cyclosporin A in the treatment of lupus nephritis].

The aim of this study is to compare the effects of low dose cyclosporin A (CsA) and intravenous cyclophosphamide pulses (IV-CTX) in the treatment of lupus nephritis (LN). Thirty patients were included in the study with 15 in each group. The improvement of ESR and proteinuria and the increase of serum albumin were observed in the CsA group, but not in the IV-CTX group at the early stage of the therapy, though the overall effects were similar. The conclusion is that the use of low dose CsA could quench the activity of LN at the early stage of the therapy, reduce the doses of steroid and CTX and minimire their side effects. IV-CTX was added to 8 cases of LN before CsA treatment had been tapered of or withdrawn. The results indicated that this regimen could effectively prevent the relapse of LN after the withdrawal of CsA therapy. It is an effective and valuable therapy.

Adolescent↗
PubMed1994

[Protective effect of captopril on cultured rat myocardial cells with anoxia and reoxygenation injury].

The effect of captopril (Cap) on electric activity of cultured rat myocardial cells under anoxia and reoxygenation was studied with standard microelectrode techniques. Results showed that anoxic solution caused lowerings of MDP, APA, and Vmax, and a shortening of APD50. All myocytes revealed multiform arrhythmias, and most cells stopped beating within 30 min, while only 40% of the cells exhibited arrhythmias but none stopped beating in the presence of 40 mg.L-1 under the same condition. During reoxygenation, most cells resumed beating in 10 min but some of these cells stopped beating again. The electric activities in rebeating cells during reoxygenation for 30 min were lower than those in normoxic cells. Cap (40 mg.L-1)-treated cells rebeat quickly after reoxygenation and no cell stopped beating any more, with parameters higher than those in untreated cells. These results demonstrate that Cap yields some beneficial effects on preventing anoxia and reoxygenation injury in cultured rat myocardial cells.

Action Potentials↗
PubMed1994

Effects of kappa-selenocarrageenan on membrane fluidity and ghost reseal ability of rat erythrocyte.

Effects of kappa-selenocarrageenan (kappa-SeC) on membrane fluidity and ghost reseal ability of rat erythrocyte were studied by measuring the fluorescence polarization and the NADH-cytochrome C oxido-reductase, respectively. After rats were given ig kappa-SeC 140 mg.kg-1.d-1 x 30 d, the fluorescence polarization was decreased in comparison with saline control group (P < 0.05). It suggested that kappa-SeC increased the membrane fluidity. The reseal ability of erythrocyte membrane (ghost) was also elevated after ig kappa-SeC 140 and 70 mg.kg-1.d-1 x 30 d (P < 0.05).

Animals↗
PubMed1994

[Selective arterial embolization in the management of hemoperitoneum caused by trophoblastic disease].

In the field of gynecologic oncology, surgical intervention has been the traditional management of hemoperitoneum. Recently selective arterial embolization has been reported to effectively control gastrointestinal bleeding caused by peptic ulcer and postoperative abdominal or retroperitoneal bleeding associated with gynecologic malignancy. This study reports the use of selective arterial embolization in the management of hemoperitoneum caused by trophoblastic disease. Analysis of 4 cases provides valuable information which enhances the safety and efficiency of this procedure. Results suggest that selective arterial embolization should be considered in the management of hemoperitoneum caused by trophoblastic disease.

Adult↗
PubMed1994

Neural network approaches to visual motion perception.

This paper concerns certain difficult problems in image processing and perception: neurocomputation of visual motion information. The first part of this paper deals with the spatial physiological integration by the figure-ground discrimination neural network in the visual system of the fly. We have outlined the fundamental organization and algorithms of this neural network, and mainly concentrated on the results of computer simulations of spatial physiological integration. It has been shown that the gain control mechanism, the nonlinearity of synaptic transmission characteristic, the interaction between the two eyes, and the directional selectivity of the pool cells play decisive roles in the spatial physiological integration. In the second part, we have presented a self-organizing neural network for the perception of visual motion by using a retinotopic array of Reichardt's motion detectors and Kohonen's self-organizing maps. It has been demonstrated by computer simulations that the network is able to learn to solve the ambiguities given by local motion detection mechanism. The resultant self-organized configuration in the output layer is resembling direction selective columns which first appear in area MT of the primate visual system. It has been explored that the spatio-temporal coherences, mapping, cooperation, competition, and Hebb rule are the basic neural principles for visual motion perception.

Animals↗
PubMed1993

[Preservation of PCNA in different fixatives and demonstration of PCNA as well as membrane antigen by double labelling technique].

Four fixatives were used with two different fixation times in order to determine the influence of different fixatives on PCNA preservation. The result indicated that the aldehyde-base fixatives preserved PCNA excellently and the appropriate fixative time was 24 hours. The result of alcohol-base fixative on PCNA preservation seemed unsatisfactory and 10% buffer formalin was the best one among the aldehyde-base fixatives for this preservation. Additionally, double-labelling technique for demonstrating PCNA as well as the membrane antigen in the same slide was established. Selection of antigen chromogens suitable to double-labelling is described.

Adenocarcinoma↗