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Y Ding

Publications and source records attributed to Y Ding.

At least 181 records · Page 10Linked to original sources
PubMed1999

[Microsatellite instability: a potential tool for the study of life sciences].

Microsatellites are simply repeated nucleotide sequences scattered throughout the human genome. They are highly polymorphic among human population and inherited in a stable manner. The microsatellite instability (MI) is highly polymorphic, which is associated with the defects in DNA mismatch repair genes. MI has been widely used by scientists to study the tumorigenesis. On the basis of their findings, a "mutator that mutates the other mutator" model for tumorigenesis has been proposed. MI is also a potential tool for the study of genetics, aging and other life sciences.

Base Pair Mismatch↗
PubMed1999

[Investigation of association parameters of basic drugs to human serum albumin by capillary zone electrophoresis/frontal analysis].

A CZE/FA method was applied to the study of association parameters of basic drugs, verapamil (VER) and propranolol (PRO), to human serum albumin (HSA) under drug-HSA association equilibria. After the direct hydrodynamic injection of a drug-HSA mixed solution into a coated capillary (effective length, 32 cm; 50 microns i.d.), the basic drug is eluted as a zonal peak with a plateau region under condition of phosphate buffer (pH 7.4, ionic strength = 0.17) at 10 kV running voltage. The unbound concentration of drug can be determined from the plateau peak height with good linear response, r = 0.999 for both VER(n = 6) and PRO(n = 8), respectively. Six VER-HSA solutions (containing 50-175 mumol/L of VER and 450-325 mumol/L of HSA) and eight PRO-HSA solutions (containing 50-400 mumol/L of VER and 450-100 mumol/L of HSA) were investigated. Three analytical methods were used for the present CZE/FA system including Scatchard, Klotz and non-linear regression analyses. The estimated association parameters were as follows: the numbers of HSA binding site n for VER were over 1.21(0.04)-1.30(0.09), binding constant, K, was between 1,690(130) and 1,790(70). Whereas for PRO, n = 0.54(0.04)-0.62(0.03), and K = 1,390(70)-1,690(180). The data deduced from these three analyses agreed well with each other.

Drug Interactions↗
PubMed1999

[Albumin-drug binding study by capillary electrophoresis. I. Quantitative applicability examination of liquid pre-column].

To measure the free concentration of verapamil (a basic drug) enantiomers in the binding system of human serum albumin(HSA), a capillary electrophoretic method, liquid precolumn(LCP), was established, and the method was examined systematically. In physiological pH condition (pH 7.4, ionic strength 0.17), HSA migrates in the opposite direction of verapamil. This electrophoretic property basically supposed the probability of preventing HSA from entering the capillary whereas a positive electric field was used. Finally, the drug enantiomers were separated by the chiral selector (45 mmol/L trimethyl-beta-cyclodextrin, pH 2.5 phosphate buffer) and the free concentration of each optical isomer in the binding system was measured. Seven samples were examined and their relative standard deviations(RSD) and the relative errors (RE) of unbound drug were 2.1%-5.02% and 1.4%-5.8%, respectively.

Drug Interactions↗
PubMed1999

[Albumin-drug binding study by capillary electrophoresis. II. Determination of drug enantiomeric binding constants].

A capillary electrophoresis (CE) method was applied to determine the binding constants of the basic racemic drug, verapamil (VER) to human serum albumin (HSA) under drug-HSA binding equilibrium (in phosphae buffer pH 7.4, ionic strength = 0.17). In coated capillary, the unbound basic drug eluted as two zonal plateau peaks due to enantiomers separated by chiral selector (45 mmol/L trimethyl-beta-cyclodextrin dissolved in pH 2.5 phosphate buffer) at 15 kV, and their concentrations can be determined from the peak heights. To avoid disturbing the VER-HSA equilibrium, the pH 7.4 solution was used as the inlet vial buffer, and a plug(about 3 cm long) of this buffer was introduced to the capillary before injection of analyte. The binding constants were obtained from linear regression plots. The unbound concentration of S-VER was 1.67 times higher than that of the antipode for the solution 300 mumol/L (+/-) VER-500 mumol/L HSA, while 1.13 for 100 mumol/L (+/-) VER-100 mumol/L HSA. The study confidently provides the binding constants of VER enantiomers to HSA, which are KR = 2.7 x 10(3) (+/- 4.4 x 10(2)) and Ks = 8.5 x 10(3) (+/- 1.0 x 10(2)).

Binding, Competitive↗
PubMed1998

Nitric oxide does not initiate but potentiates glucose-induced insulin secretion in pancreatic beta-cells.

The role of nitric oxide (NO) in glucose-induced insulin secretion was studied in pancreatic beta-cells, HIT-T15. A role for NO is suggested since glucose stimulated NO production in a concentration-dependent manner. NG-monomethyl-L-arginine, a potent inhibitor of nitric oxide synthase, significantly inhibited glucose-induced nitric oxide production as well as insulin release in HIT-T15. Furthermore, this inhibitory effect can be reversed by sodium nitroprusside (SNP), a well known NO donor. While SNP alone did not stimulate insulin release, it potentiated the secretory response of HIT-T15 cells to glucose by approximately two-fold. Potentiation by SNP appears to be mediated by NO, since (i) the potentiation was completely abolished by 10 microM hemoglobin, a scavenger of NO; and (ii) was not affected by rhodanese plus sodium thiosulphate. Neither hemoglobin alone nor the combination of rhodanese and sodium thiosulphate had any effect on glucose induced insulin release. These results are consistent with the hypothesis that glucose-induced formation of NO may potentiate the effect of glucose by a positive feedback mechanism.

Drug Interactions↗
PubMed1998

Promoter activation and following induction of the p21/WAF1 gene by flavone is involved in G1 phase arrest in A549 lung adenocarcinoma cells.

Flavonoids are present in many plants including edible fruits and vegetables. Recently, many of the biological activities of flavonoids have been elucidated. Flavone is a well known flavonoid, and many of its derivatives have been shown to have anti-proliferative effects on several cancer cells. We report here that flavone can effectively inhibit the cell growth of human lung adenocarcinoma A549 cells in a dose-dependent manner, and 100 microM flavone causes cell cycle arrest at the G1 phase. As a mechanism underlying the cell cycle arrest, flavone markedly increases the mRNA and protein levels of a universal inhibitor of cyclin-dependent kinase, p21/WAF1, and inhibits phosphorylation of retinoblastoma (RB) protein. Although A549 cells possess wild-type p53, flavone does not induce the p53 protein, suggesting that p21/WAF1 induction is p53-independent. In addition, 100 microM flavone significantly increases the promoter activity of the p21/WAF1 gene by 5-fold. These results suggest that the G1 phase arrest by flavone is due to p53-independent transcriptional induction of the p21/WAF1 gene and the subsequent dephosphorylation of RB protein.

Adenocarcinoma↗
PubMed1998

Efficient synthesis of 3'-glycosylated LacNAc-based oligosaccharides.

LacNAc-based oligosaccharides, including sialyl-(2-->3)-LacNAc, dimeric sialyl-(2-->3)-LacNAc, trimeric sialyl-(2-->3)-LacNAc, beta-glucuronyl-(1-->3)-LacNAc, and 3-sulfo-beta-glucuronyl-(1-->3)-LacNAc, were synthesized efficiently from a single protected LacNAc derivative having both OH-3' and 4' unprotected.

Amino Sugars↗
PubMed1998

A reduction-pyrolysis-catalysis synthesis of diamond

Diamond powder was synthesized through a metallic reduction-pyrolysis-catalysis route with the reaction of carbon tetrachloride and sodium at 700 degreesC, in which the sodium was used as reductant and flux. This temperature is much lower than that of traditional methods. The x-ray powder diffraction patterns showed three strong peaks of diamond. The Raman spectrum showed a sharp peak at 1332 inverse centimeters, which is characteristic of diamond. Although the yield was only 2 percent, this method is a simple means of forming diamond.

Journal Article↗
PubMed1998

Efficient transfer of genes into murine cardiac grafts by Starburst polyamidoamine dendrimers.

Starburst dendrimer, a structurally defined, spherical macromolecule composed of repeating polyamidoamino subunits, was investigated to augment plasmid-mediated gene transfer efficiency in a murine cardiac transplantation model. The grafts were directly injected with naked pCH110, a plasmid encoding beta-galactosidase (beta-Gal), or pCH110-dendrimer complex, and reporter gene expression determined by X-Gal staining. The grafts injected with pCH110-dendrimer demonstrated widespread and extended beta-Gal expression in both myocytes and the graft infiltrating cells from 7 to 28 days, compared to the grafts injected with naked pCH110 that expressed beta-Gal only in myocytes for less than 14 days. p alphaMHC-vIL-10, as plasmid encoding viral interleukin-10 (vIL-10) under the control of alpha-myosin heavy chain promoter, was able to prolong allograft survival from 13.9 +/- 0.9 days to 21.4 +/- 2.3 days (p < 0.005). When dendrimer G5EDA was used with p alphaMHC-vIL-10, 60-fold less DNA resulted in significant prolongation of graft survival to 38.6 +/- 4.7 days (p < 0.0005). The dose of DNA, the charge ratio of DNA to dendrimer, and the size generation of the dendrimers were all determined to be critical variables for prolongation of allograft survival in this model system. Thus, the use of the Starburst dendrimer dramatically increased the efficiency of plasmid-mediated gene transfer and expression. Production of immunosuppressive cytokines at higher amounts for longer periods of time in a greater expanse of tissue enhanced the immunosuppressive effect and prolonged graft survival further.

Animals↗
PubMed1998

Expression cloning of a human sulfotransferase that directs the synthesis of the HNK-1 glycan on the neural cell adhesion molecule and glycolipids.

The HNK-1 carbohydrate is expressed on various adhesion molecules in the nervous system and is suggested to play a role in cell-cell and cell-substratum interactions. Here we describe the isolation and functional expression of a cDNA encoding a human sulfotransferase that synthesizes the HNK-1 carbohydrate epitope. A mutant Chinese hamster ovary cell line, Lec2, which stably expresses human neural cell adhesion molecule (N-CAM) (Lec2-NCAM), was first established. Lec2-NCAM was co-transfected with a human fetal brain cDNA library, a cDNA encoding the rat glucuronyltransferase that forms a precursor of the HNK-1 carbohydrate, and a vector encoding the polyoma large T antigen. The transfected Lec2-NCAM cells expressing the HNK-1 glycan were enriched by fluorescence-activated cell sorting. Sibling selection of recovered plasmids resulted in a cDNA encoding a sulfotransferase, HNK-1ST, that directs the expression of the HNK-1 carbohydrate epitope on the cell surface. The deduced amino acid sequence indicates that the enzyme is a type II membrane protein. Sequence analysis revealed that there is a short amino acid sequence in the presumed catalytic domain, which is highly homologous to the corresponding sequence in other Golgi-associated sulfotransferases so far cloned. The amount of HNK-1ST transcript is high in fetal brain compared with fetal lung, kidney, and liver. Expression of HNK-1ST resulted in the formation of the HNK-1 epitope on N-CAM and a soluble chimeric form of HNK-1ST was shown to add a sulfate group to a precursor, GlcAbeta1-->3Galbeta1-->4GlcNAcbeta1-->R, forming sulfo-->3GlcAbeta1-->3Galbeta1-->4GlcNAcbeta1-->R. The results combined together indicate that the cloned HNK-1ST directs the synthesis of the HNK-1 carbohydrate epitope on both glycoproteins and glycolipids in the nervous tissues.

Amino Acid Sequence↗
PubMed1998

Synaptic and neurochemical characterization of parallel pathways to the cytochrome oxidase blobs of primate visual cortex.

The primary visual cortex (V1) of primates is unique in that it is both the recipient of visual signals, arriving via parallel pathways (magnocellular [M], parvocellular [P], and koniocellular [K]) from the thalamus, and the source of several output streams to higher order visual areas. Within this scheme, output compartments of V1, such as the cytochrome oxidase (CO) rich blobs in cortical layer III, synthesize new output pathways appropriate for the next steps in visual analysis. Our chief aim in this study was to examine and compare the synaptic arrangements and neurochemistry of elements involving direct lateral geniculate nucleus (LGN) input from the K pathway with those involving indirect LGN input from the M and P pathways arriving from cortical layer IV. Geniculocortical K axons were labeled via iontophoretic injections of wheat germ agglutinin-horseradish peroxidase into the LGN and intracortical layer IV axons (indirect P and M pathways to the CO-blobs) were labeled by iontophoretic injections of Phaseolus vulgaris leucoagglutinin into layer IV. The neurochemical content of both pre- and postsynaptic profiles was identified by postembedding immunocytochemistry for gamma-amino butyric acid (GABA) and glutamate. Sizes of pre- and postsynaptic elements were quantified by using an image analysis system, BioQuant IV. Our chief finding is that K LGN axons and layer IV axons (indirect input from M and P pathways) exhibit different synaptic relationships to CO blob cells. Specifically, our results show that within the CO blobs: 1) all K cell axons contain glutamate, and the vast majority of layer IV axons contain glutamate with only 5% containing GABA; 2) K axons terminate mainly on dendritic spines of glutamatergic cells, while layer IV axons terminate mainly on dendritic shafts of glutamatergic cells; 3) K axons have larger boutons and contact larger postsynaptic dendrites, which suggests that they synapse closer to the cell body within the CO blobs than do layer IV axons. Taken together, these results suggest that each input pathway to the CO blobs uses a different strategy to contribute to the processing of visual information within these compartments.

Animals↗
PubMed1998

Reduced expression of the macrophage scavenger receptors in macrophage-like cell mutants resistant to brefeldin A.

Brefeldin A (BFA)-resistant mutants, JB15, JB23 and JB33, were isolated from mutagenized murine macrophage-like (J774) cells and their modified low density lipoprotein (LDL) metabolism was studied. When JB23 cells, the most resistant clone, were incubated with acetylated LDL, intracellular accumulation of cholesteryl esters (CE) was reduced by 31% as compared with J774 cells. The cell-association of 125I-acetyl-LDL with, and subsequent endocytic degradation by JB23 cells were reduced by 40-60% compared with J774 cells. Western and Northern blot analyses showed that the protein and mRNA levels of the macrophage scavenger receptors (MSR) were reduced by 68% and 55% respectively in JB23 cells as compared with those in J774 cells. These results indicate that a putative BFA-target molecule(s) might regulate MSR gene expression as well as macrophage-derived foam cell formation.

Animals↗
PubMed1998

Lead-induced hypertension. II. Response to sequential infusions of L-arginine, superoxide dismutase, and nitroprusside.

Administration of 100 ppm lead acetate daily for 3 months caused hypertension in Sprague-Dawley rats, with reversal by treatment with 2,3-dimercaptosuccinic acid (DMSA) (0.5% for 2 weeks). Animals from each group were infused sequentially in 30-min intervals with saline (S), L-arginine (Arg), Arg+ superoxide dismutase (SOD), S, and sodium nitroprusside (SNP). Baseline mean blood pressure (MBP) was elevated in lead-treated animals (Pb) compared to that in controls(C), returning toward normal after DMSA (105 +/- 2 mmHg, C, vs 149 +/- 2, Pb, and 124 +/- 1, DMSA, P < 0.001). Infusion of Arg caused a fall in MBP in all animals, normalizing the MBP in Pb-treated animals. SNP caused a greater fall in MBP in all groups of animals, normalizing the MBP in Pb. Measurement of urinary nitrite + nitrate (NOx) by chemiluminescence revealed at baseline a reduced level in Pb, restored to normal by DMSA (6.6 +/- 1.5 nmol/min/100 g BW, C, vs 3.3 +/- 1.7, Pb, P < 0.05, vs 5.8 +/- 2.6, DMSA, P = NS). Infusion of arginine increased urinary NOx in all groups, but to a lesser degree in Pb and DMSA. Assay of plasma malondialdehyde (MDA) by HPLC, as a measure of reactive oxygen species (ROS), was elevated at baseline in Pb, reduced by DMSA (3.6 +/- 0.4 mumol/L, Pb, vs 1.9 +/- 0.2, C, and 1.9 +/- 0.3, DMSA, P < 0.01). In the Pb group, SOD resulted in a significant fall in MDA (2.0 +/- 0.3 mumol/L, SOD, vs 3.1 +/- 0.1, Arg, P < 0.01), but no further fall in MBP or increase in urinary NOx. Thus, hypertension in lead-exposed animals is related to both diminished NO and increased ROS. The elevation in MBP can be ameliorated by additional NO through infusion of substrate arginine or by treatment with the ROS scavenger, DMSA. Lead-exposed animals show enhanced MBP sensitivity to the NO donors, Arg and SNP, but no further response to SOD, despite a reduction in MDA to normal. We speculate that lead-induced hypertension may be caused by one species of ROS which enhances vascular reactivity, and that provision of additional NO acts to scavenge the ROS and/or acts directly as a vasodilator.

Animals↗
PubMed1998

Cervical ripening in the third trimester of pregnancy with intravaginal misoprostol: a double-blind, randomized, placebo-controlled study.

To evaluate the safety and efficacy of intravaginal misoprostol for cervical ripening in the third trimester, a randomized, double-blind, placebo-controlled trial was conducted in 85 patients indicated for induction of labor and with unfavorable cervices. They were randomly assigned to receive either intravaginal misoprostol (100 mg) or placebo placed in the posterior vaginal fornix. The Bishop score, fetal heart rate and Doppler blood flow velocity waveforms were measured before and 12 h after drug administration. Placenta and decidu were histopathologically observed in some cases. Among 85 patients enrolled, 43 received misoprostol and 42 received placebo. Whereas the mean initial Bishop scores were not significantly different between the two groups, the mean Bishop score in misoprostol group was significantly better than those in placebo group. The mean change in Bishop score was also significantly different (4.4 for misoprostol versus 1.0 for placebo, P < 0.01). The prevalence of spontaneous onset of labor within 12 h after drug insertion in misoprostol group (67.4%, 29/43) was significantly higher than that in placebo group (14.3%, 6/42), P < 0.01. The average Doppler velocity systolic to diastolic (S/D) ratios of umbilical artery, middle cranial artery, renal artery were not significantly different before and 12 h after drug insertion between both groups. There was no significant difference in frequency of abnormal fetal heart rate tracings or fetal distress and in the mean Apgar scores between the two groups. Except the presence of vasodilation in villi vessels in the misoprostol group, the placental and decidual histopathological changes had no significantly difference between two groups. It is concluded that intravaginal misoprostol may be an effective and safe cervical ripening agent in the third trimester of pregnancy.

Administration, Intravaginal↗
PubMed1998

Neurite promotion from ciliary ganglion neurons by gicerin.

Gicerin is a cell adhesion molecule of an immunoglobulin superfamily member and transiently expressed on the surface of neurons such as retinal ganglion cells during synaptogenesis. Gicerin is a receptor for NOF (neurite outgrowth factor) that belongs to the laminin family, and mediates neurite extension induced by NOF. As we have reported, gicerin also exhibits homophilic cell adhesion activity, we compared the patterns of extending neurites induced by homophilic and heterophilic cell adhesion activities of gicerin using ciliary ganglion (CG) neurons. CG neurons expressed gicerin and extended neurites on a feeder layer of gicerin-transfected cells, suggesting a neurite extension by gicerin-gicerin (homophilic) interaction. We found that CG neurons cultured on gicerin-transfected cells extended slightly branched neurites, while those cultured on NOF-coated substratum extended many long branched neurites. It is suggested that neurites induced by homophilic or heterophilic cell adhesion activities of gicerin differ in the length and branching.

Animals↗
PubMed1998

Relevance of kinetochore size and microtubule-binding capacity for stable chromosome attachment during mitosis in PtK1 cells.

Chromosomes attach to the mitotic spindle via their kinetochores. The average number of spindle microtubules binding to each kinetochore varies with species, the stage of mitosis, and the length of time that the kinetochore has been attached to the spindle. In this report, we investigate how kinetochore microtubule number varies with kinetochore size and chromosome size in PtK1 cells. From an analysis of serial-section electron micrographs, we determined that the average surface area of metaphase, taxol-treated metaphase, and anaphase kinetochores is 0.16 +/- 0.05 microm2 (N = 181). Surprisingly, kinetochore microtubules are packed more densely on the smaller kinetochores, as seen by a reduction in the average spacing between kinetochore microtubules from 89 nm to 59 nm. Our interpretation of this result is that PtK1 cells require a minimum kinetochore microtubule-binding capacity for survival during repeated rounds of mitotic division. We estimate the lower limit to be 23 kinetochore microtubules and suggest that this capacity is required to ensure stable attachment during the dynamic and highly stochastic process of kinetochore fiber formation. There is a modest but statistically significant increase in kinetochore microtubule number with chromosome size, indicating that chromosome size is a minor determinant of kinetochore microtubule number.

Animals↗