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Biomedical subjects

Y Ding

Publications and source records attributed to Y Ding.

At least 163 records · Page 9Linked to original sources
PubMed1999

Tetrodotoxin suppresses morphological enhancement of the metastatic MAT-LyLu rat prostate cancer cell line.

Voltage-gated Na+ channels are expressed by highly metastatic MAT-LyLu cells, but not by poorly metastatic AT-2 cells, derived from the rodent Dunning model of prostatic cancer. We have investigated the possible involvement of these channels in the morphological development of the cells. Incubation of both the MAT-LyLu and the AT-2 cell line for 24 h with the Na+ channel blocker tetrodotoxin (TTX) at 6 microM altered the morphology only of the MAT-LyLu cell line. TTX produced significant decreases in: (a) cell process length and (b) field diameter, and increases in (c) cell body diameter and (d) process thickness. Importantly, 6 microM TTX had no significant effects on proliferation rates or cellular toxicity. The results suggest that Na+ channel activity plays a significant role in determining the morphological development of MAT-LyLu cells in such a way as to enhance their metastatic potential.

Animals↗
PubMed1999

Feasibility studies of simultaneous multianalyte amperometric immunoassay based on spatial resolution.

A multianalyte immunoassay concept based on the geometric separation of different analyte-specific antibodies has been demonstrated. The assay and amperometric detection are done in a cell with two working electrodes controlled at the same potential, and the amperometric signal at each electrode is monitored. The distance between any two adjacent electrodes in this prototype is 2.5 mm, and during the course of amperometric measurement, the product formed at one electrode does not reach the other working electrode within 20 min after the addition of enzyme substrate. Thus, the method relies on the spatial resolution between the different antibodies being such that measurements are taken before cross-interference due to diffusion can occur. Identical enzyme labels (alkaline phosphatase, ALP) and substrates (p-aminophenyl phosphate, PAPP) are used for all analytes. Alkaline phosphatase-conjugated rat anti-mouse IgG was immobilized by passive adsorption. Our studies showed that this concept is feasible and can be applied to the simultaneous measurement of multiple analytes.

Algorithms↗
PubMed1999

Aglycone structure influences alpha-fucosyltransferase III activity using N-acetyllactosamine glycoside acceptors.

We showed previously that Chinese hamster ovary cells took up and utilized a variety of N-acetylglucosaminides as primers of oligosaccharide biosynthesis (Ding et al., 1999, J. Carbohydr. Chem., 18:471-475). In this study, a library of N-acetylglucosaminides was enzymatically galactosylated in vitro to yield type 2 chain N-acetyllactosaminides bearing a variety of aglycones. Those disaccharides are potential acceptors for fucosyltransferases. As an extension of the previous study, we tested the type 2 chain disaccharyl glycosides (Galbeta1,4-GlcNAcbeta-R) for their aglycone-dependent acceptor specificity for alpha-L-fucosyltransferase III (Fuc-TIII). The enzyme activity significantly depended on the aglycone structures, suggesting that, in addition to the polar groups on the sugar moiety, the hydrophobic aglycone can substantially contribute to recognition in this reaction.

Amino Sugars↗
PubMed1999

Direct binding of purified HLA class I antigens by soluble NKG2/CD94 C-type lectins from natural killer cells.

Human natural killer (NK) cell cytotoxicity is inhibited following human leucocyte antigen (HLA) class I binding by killer cell inhibitory receptors belonging to the immunoglobulin or C-type lectin protein families. Of the latter family, CD94 and NKG2A or -B associate to inhibit NK cell cytotoxicity. We have constructed C-Myc epitope-tagged soluble NKG2A, -B, -C, -D and human NKR-P1 lectin domains, and studied their ability to associate with Flu-tagged soluble CD94 lectin domains. Furthermore, their ability to bind solubilized immunoaffinity-purified HLA class I antigens, either alone or following association with CD94 lectin domains, was evaluated using flow cytometry and Western blot analyses. We show that soluble NKG2A, -B and -C lectin domains interact with CD94 lectin domains to form complexes, whereas NKG2D and human NKR-P1 lectin domains do not. Soluble NKG2C, -D and CD94 lectin domains bind solubilized affinity purified HLA class I antigens on their own, whereas NKG2A and -B require association with CD94 lectin domains for binding. Soluble human NKR-P1 lectin domains do not bind solubilized HLA class I antigens in our system.

Animals↗
PubMed1999

Interaction of heme oxygenase-2 with nitric oxide donors. Is the oxygenase an intracellular 'sink' for NO?

Heme oxygenase-2 (HO-2) is the constitutive cognate of the heat-shock protein-32 family of proteins. These proteins catalyze oxidative cleavage of heme to CO and biliverdin, and release Fe. HO-2 is a hemoprotein and binds heme at heme regulatory motifs (HRMs) with a conserved Cys-Pro pair; two copies of HRM are present in HO-2 (Cys264 and Cys281). The HO-2 HRMs are not present in HO-1 and are not involved in HO-2 catalytic activity. Optical CD, and spectral and activity analyses were used to examine reactivity of HO isozymes with NO species produced by NO donors. Purified Escherichia coli-expressed HO preparations, wild-type HO-2, Cys264/Cys281 --> Ala/Ala HO-2-mutant (HO-2-mut) and HO-1 preparations were used. A type II change (red shift) of the Soret band (405 nm --> 413-419 nm) was observed when wild-type HO-2 was treated with sodium nitroprusside (SNP), S-nitroglutathione (GSNO), S-nitroso-N-acetylpenicillamine (SNAP) or 3-morpholinosydnonimine (SIN-1); the NO scavenger, hydroxocobalamin (HCB) prevented the shift. Only SIN-1, which produces peroxynitrite by generating both NO and superoxide anion, decreased the Soret region absorption and the pyridine hemochromogen spectrum of HO-2; superoxide dismutase (SOD) blocked the decrease. Binding of heme to HO-2 protein was required for shift and/or decrease in absorption of the Soret band. NO donors significantly inhibited HO-2 activity, with SNP being the most potent inhibitor (> 40%). Again, trapping NO with HCB blocked HO-2 inactivation. HO-1 and HO-2-mut were not inactivated by NO donors. CD data suggest that the decrease in HO-2 activity was not related to change by NO species of the secondary structure of HO-2. Western blot analysis suggests that NO donors did not cause HO-1 protein loss and Northern blot analysis of HeLa cells treated with SIN-1 and SNP indicates that, unlike HO-1 mRNA, which is remarkably responsive to the treatments, HO-2 mRNA levels were modestly increased ( approximately two to threefold) by NO donors. The data are consistent with the possibility that NO interaction with HO-2-bound heme effects electronic interactions of residues involved in substrate binding and/or oxygen activation. The findings permit the hypothesis that HO-2 and NO are trans-inhibitors, whereby biological activity of NO is attenuated by interaction with HO-2, serving as an intracellular 'sink' for the heme ligand, and NO inhibits HO-2 catalytic activity. As such, the cellular level of both signaling molecules, CO and NO would be moderated.

Animals↗
PubMed1999

Increased nitric oxide inactivation by reactive oxygen species in lead-induced hypertension.

BACKGROUND: We have recently found evidence for increased reactive oxygen species (ROS) in rats with lead-induced hypertension. We hypothesized that increased ROS activity may contribute to hypertension by enhancing inactivation of nitric oxide (NO) in this model. METHODS: Rats were treated for 12 weeks with either lead acetate (100 p.p.m.) alone (Pb group) or lead acetate plus vitamin E-fortified food (5000 U/kg rat chow, Pb + E group). The control animals were fed either regular rat chow or a vitamin E-fortified diet. Blood pressure, creatinine clearance, and urinary excretion of stable NO metabolites (NOx) were monitored, and plasma and tissue abundance of nitrotyrosine, which is the footprint of NO oxidation by ROS, were determined. RESULTS: The Pb group showed a marked rise in blood pressure, a significant increase in plasma and kidney, heart, liver, and brain nitrotyrosine abundance, and a substantial fall in urinary NOx excretion. Concomitant administration of high-dose vitamin E in the Pb + E group ameliorated hypertension and normalized both urinary NOx excretion and tissue nitrotyrosine without altering tissue lead content. However, vitamin E supplementation had no discernible effect on either blood pressure or nitrotyrosine abundance in the normal controls. CONCLUSIONS: These findings point to enhanced ROS-mediated inactivation and sequestration of NO, which can potentially contribute to hypertension, tissue damage, and reduced urinary NOx excretion in rats with lead-induced hypertension. The beneficial effects of high-dose vitamin E on blood pressure, tissue nitrotyrosine burden, and urinary NOx excretion support the role of increased ROS activity in the pathogenesis of these abnormalities in this model.

Animals↗
PubMed1999

Cytotoxicity of [125I]iodoHoechst 33342: contribution of scavengeable effects.

PURPOSE: The incubation of the DNA minor-groove binder [125I]iodoHoechst 33342 (125IH) with plasmid DNA leads to the production of one double-strand break (dsb) per decay, both in the presence and absence of dimethylsulfoxide (DMSO). In contrast, when 125I is incorporated into mammalian cell DNA as an iodinated pyrimidine base, DMSO decreases the dsb yield and enhances survival. Because these variations in radioprotective effects may be due either to the location of 125I vis-à-vis the DNA helix or to differences in DNA architecture, the toxicity of 125IH and its modification by DMSO were examined in mammalian cells. METHODS: Uptake and retention of 125IH in V79 cells were measured, and survival was determined after accumulation of 125I decays at 0.3 degrees C +/-10% DMSO. RESULTS: A linear-quadratic survival curve was obtained both in the absence [D37 = 114+/-36 decays/cell, alpha = (5.39 1.17) x10(-3) cell/decay] and presence [D37 = 211+/-65 decays/cell, alpha = (1.27+/-0.52) x10(-3) cell/decay] of DMSO. The dose modification factor for the linear component of the survival curve was 4.25+/-1.97, indicating the predominance of indirect mechanisms. This value is similar to that obtained with DNA-incorporated 125I (4.05+/-1.72) and for the initial slope (alpha) of 137Cs gamma-rays (4.43+/- 1.41). CONCLUSIONS: Cytotoxicity resulting from the decay of the Auger electron emitter 125I in the mammalian cell nucleus is caused mainly by indirect mechanisms.

Animals↗
PubMed1999

Characterization of mammalian UDP-GalNAc:glucuronide alpha 1-4-N-acetylgalactosaminyltransferase.

We previously reported that cultured cells incubated with beta-xylosides synthesized alpha-GalNAc-capped GAG-related xylosides, GalNAc alpha GlcA beta Gal beta Gal beta Xyl beta-R and GalNAc alpha GlcA beta GalNAc beta GlcA beta Gal beta Gal beta Xyl beta-R, where R is 4-methylumbelliferyl or p-nitrophenyl (Manzi et al., 1995; Miura and Freeze, 1998). In this study, we characterized an alpha-N-acetylgalactosaminyltransferase (alpha-GalNAc-T) that probably adds the alpha-GalNAc residue to the above xylosides. Microsomes from several animal cells and mouse brain contained the enzyme activity which requires divalent cations, and has a relatively broad pH optimal range around neutral. The apparent K(m) values were in the submillimolar range for the acceptors tested, and 19 microM for UDP-GalNAc. 1H-NMR analysis of the GlcA-beta-MU acceptor product showed the GalNAc residue is transferred in alpha 1,4-linkage to the glucuronide, which is consistent with previous results reported on alpha-GalNAc-capped Xyl-MU (Manzi et al., 1995). Various artificial glucuronides were tested as acceptors to assess the influence of the aglycone. Glucuronides with a bicyclic aromatic ring, such as 4-methylumbelliferyl beta-D-glucuronide (GlcA-beta-MU) and alpha-naphthyl beta-D-glucuronide, were the best acceptors. Interestingly, a synthetic acceptor that resembles the HNK-1 carbohydrate epitope but lacking the sulfate group, GlcA beta 1,3Gal beta 1,4GlcNAc beta-O-octyl (delta SHNK-C8), was a better acceptor for alpha-GalNAc-T than the glycosaminoglycan-protein linkage region tetrasaccharyl xyloside, GlcA beta 1,3Gal beta 1,3Gal beta 1,4Xyl beta-MU. GlcA-beta-MU and delta SHNK-C8 competed for the alpha-GalNAc-T activity, suggesting that the same activity catalyzes the transfer of the GalNAc residue to both acceptors. Taken together, the results show that the alpha-GalNAc-T described here is not restricted to GAG-type oligosaccharide acceptors, but rather is a UDP-GalNAc:glucuronide alpha 1-4-N-acetylgalactosaminyltransferase.

Animals↗
PubMed1999

Growth inhibition of A549 human lung adenocarcinoma cells by L-canavanine is associated with p21/WAF1 induction.

L-Canavanine (CAV) is a higher plant nonprotein amino acid and a potent L-arginine antimetabolite. CAV can inhibit the proliferation of tumor cells in vitro and in vivo, but little is known regarding the molecular mechanisms mediating these effects. We demonstrated that the treatment of human lung adenocarcinoma A549 cells with CAV caused growth inhibition; G1 phase arrest is accompanied by accumulation of an incompletely phosphorylated form of the retinoblastoma protein, whose phosphorylation is necessary for cell cycle progression from G1 to S phase. In addition, CAV induces the expression of p53 and subsequent expression of a cyclin-dependent kinase inhibitor, p21/WAF1. The p53-dependent induction of p21/WAF1 and the following dephosphorylation of the retinoblastoma protein by CAV could account for the observed CAV-mediated G1 phase arrest.

Adenocarcinoma↗
PubMed1999

Nitric oxide synthase expression in the course of lead-induced hypertension.

We recently showed elevated reactive oxygen species (ROS), reduced urinary excretion of NO metabolites (NOx), and increased NO sequestration as nitrotyrosine in various tissues in rats with lead-induced hypertension. This study was designed to discern whether the reduction in urinary NOx in lead-induced hypertension is, in part, due to depressed NO synthase (NOS) expression. Male Sprague-Dawley rats were randomly assigned to a lead-treated group (given lead acetate, 100 ppm, in drinking water and regular rat chow), a group given lead and vitamin E-fortified chow, or a normal control group given either regular food and water or vitamin E-fortified food for 12 weeks. Tail blood pressure, urinary NOx excretion, plasma malondialdehyde (MDA), and endothelial and inducible NOS (eNOS and iNOS) isotypes in the aorta and kidney were measured. The lead-treated group exhibited a rise in blood pressure and plasma MDA concentration, a fall in urinary NOx excretion, and a paradoxical rise in vascular and renal tissue eNOS and iNOS expression. Vitamin E supplementation ameliorated hypertension, lowered plasma MDA concentration, and raised urinary NOx excretion while significantly lowering vascular, but not renal, tissue eNOS and iNOS expression. Vitamin E supplementation had no effect on either blood pressure, plasma MDA, or NOS expression in the control group. The study also revealed significant inhibition of NOS enzymatic activity by lead in cell-free preparations. In conclusion, lead-induced hypertension in this model was associated with a compensatory upregulation of renal and vascular eNOS and iNOS expression. This is, in part, due to ROS-mediated NO inactivation, lead-associated inhibition of NOS activity, and perhaps stimulatory actions of increased shear stress associated with hypertension.

Animals↗
PubMed1999

A 12-Mb complete coverage BAC contig map in human chromosome 16p13.1-p11.2.

We have constructed a complete coverage BAC contig map that spans a 12-Mb genomic segment in the human chromosome 16p13.1-p11.2 region. The map consists of 68 previously mapped STSs and 289 BAC clones, 51 of which-corresponding to a total of 7.721 Mb of genomic DNA-have been sequenced, and provides a high resolution physical map of the region. Contigs were initially built based mainly on the analysis of STS contents and restriction fingerprint patterns of the clones. To close the gaps, probes derived from BAC clone ends were used to screen deeper BAC libraries. Clone end sequence data obtained from chromosome 16-specific BACs, as well as from public databases, were used for the identification of BACs that overlap with fully sequenced BACs by means of sequence match. This approach allowed precise alignment of clone overlaps in addition to restriction fingerprint comparison. A freehand contig drawing software tool was developed and used to manage the map data graphically and generate a real scale physical map. The map we present here is approximately 3.5 x deep and provides a minimal tiling path that covers the region in an array of contigous, overlapping BACs.

Base Sequence↗
PubMed1999

Pharmacokinetics of sustained-release capsule of 5-isosorbide mononitrate in 20 healthy Chinese young men.

AIM: To compare the pharmacokinetics of domestic and imported sustained-release capsule of 5-isosorbide mononitrate (5-IM). METHODS: A single and 5-d-repeated oral doses of 5-IM 50 mg were performed on 2 groups of 20 Chinese healthy subjects (10 subjects for each group) in a randomized crossover protocol. The 5-IM in plasma were measured by gas chromatography with electron-captured detector method. Data were analyzed automatically by using a CAPP program on a PC computer. RESULTS: Fitting the 5-IM concentration-time curves to one-compartment model or following trapezoidal rule, the parameters such as Tmax, Cmax, Ke, MRT, and AUC were calculated and there were no significant differences between the two kinds of capsule. The major pharmacokinetic parameters of domestic and imported 5-IM sustained-release capsule with a 5-d multiple dose were respectively: Cmax (677 +/- 103) and (702 +/- 76) micrograms.L-1; Tmax (5.1 +/- 2.0) and (5.6 +/- 1.3) h; MRT (11.5 +/- 0.5) and (11.4 +/- 0.7) h; AUC0-infinity (12,121 +/- 1346) and (12,352 +/- 988) micrograms.h.L-1. The fraction of drug absorbed in vivo was correlated well with the percentage amount of drug released in vitro at corresponding time (P < 0.05), and the fluctuation indices on d 5 in multiple dose study were not significantly different between the two formulations (P > 0.05). The relative bioavailability of the domestic capsule for single and multiple dose were 96% +/- 11% and 98% +/- 10%, respectively. CONCLUSION: Domestic 5-IM sustained-release capsule showed bioequivalence compared with the imported capsule and provided the same nitrate-low interval in the latter part of the 24-h dosing interval.

Adult↗
PubMed1999

[MRI features of lymphedema of the lower extremity: comparison with lymphangioscintigraphy].

OBJECTIVE: To investigate the features of chronic lymphedema of the extremity. METHODS: Magnetic resonance imaging (MRI) and lymphangioscintigraphy (LAS) examinations were performed on 12 patients with peripheral lymphedema. RESULTS: MRI characteristically showed diffusive subcutaneous edema, reticular lymphangiectasis and "channels" with sequestered lymph. MRI scan clearly displayed the proliferative and extended lymphatic vessels, trunks and chylocyst. LAS showed dermal diffusion (dermal backflow) or retention at the injection site of the tracer with poorly defined lymphatic trunks and delayed or no visualization of regional lymph nodes. CONCLUSION: MRI can visualise peripheral lymph trunks, lymph nodes and soft tissue. LAS is more helpful in ascertaining the condition of obstruction of lymphatic system. Using these two imaging modalities together is helpful for anatomical diagnosis and delineating the disarranged pattern of lymphedema.

Adolescent↗
PubMed1999

[Study on combined detection of M. genitalium, M. pneumoniae and C. pneumonia by nested polymerase chain reaction in respiratory tract infections in pediatric patients].

OBJECTIVE: To study the respiratory tract infections by Mg, M. genitalium (Mpn), Cpn, and co-infections by these agents in pediatric patients. METHODS: Mg DNA, Mpn DNA and Cpn DNA were detected in respiratory tract specimens obtained by throat swab from 231 children by the nested polymerase chain reaction (PCR) technique. DNA sequencings were detected and analysed between every two positive specimens of Mg and Cpn and typical strains. RESULTS: Positive rates of Mg DNA, Mpn DNA and Cpn DNA by nested PCR in 231 children were 22.5%, 30.7% and 32.9%. The Positive rates of co-infection were 5.2% (Mg and Mpn), 2.6% (Mg and Cpn), 10.8% (Mpn and Cpn) and 8.7% (Mg and Mpn and Cpn). There was only one base mutation in 1 Mg DNA. Other DNA sequencings were same as those from model strains. The homogeneity was 99.8%. CONCLUSIONS: Mg could be one of the pathogens in respiratory tract infections in pediatric patients. There exists co-infection by Mg, Mpn and Cpn.

Child↗
PubMed1999

[A clinical analysis of L-dopa induced dyskinesia treated by posteroventral pallidotomy for Parkinson's disease].

OBJECTIVE: To evaluate the outcome of microelectrode-guided posteroventral pallidotomy (PVP) for L-dopa induced dyskinesia in patients with Parkinson's disease. METHODS: Thirty-six patients with dyskinesia were evaluated with unified Parkinson's disease rating scale (UPDRS) before and after operation. Duration and disability of dyskinesia were analyzed respectively. RESULTS: The total surgical improvement for dyskinesia was 76.2%. Duration improvement was 88.8% and disability 79.7%. Significant change (P < 0.05) happened postoperatively. Seventeen patients were followed up for 3 months. The result showed a stable improvement for dyskinesia. CONCLUSIONS: L-dopa induced dyskinesia may disappear or be improved after PVP. Surgical treatment promises a maximum L-dopa therapy without any severe pharmaceutical complications. Synergic treatment of drug and surgery are a new strategy for Parkinson's disease.

Adult↗
PubMed1999

[Pollen morphology identification of five species of medicinal sanguisorba with electron microscope].

OBJECTIVE: To approach a new evidence for identifying various species of Rosaceae Sanguisorba, especially for distinguishing S. applanata from S. sitchinese. METHOD: The pollens of five species S. officinalis, S. officinalis var. longifolia, S. applanata, S. applanata var. villosa and S. sitchinese were morphologically identified with electron microscope. RESULTS: The pollens are prolate or perprolate, having six colporates and featuring sculptures of small caverns and small granules combined. The species are closed to each other in pollen morphology, bur display differences in the diameter of pollens, clarity of pore membrane and presence or absence of irregular verrucous sculptures. CONCLUSION: This paper provides a new evidence for identifying the Sanguisorba.

Microscopy, Electron, Scanning↗