Search PubMed⌕ Search

Biomedical subjects

Q Wu

Publications and source records attributed to Q Wu.

At least 217 records · Page 12Linked to original sources
PubMed1999

[Relationship between expression of estrogen receptor progestrone receptor and the biological characteristics of nasopharyngeal carcinoma].

OBJECTIVE: To Clarity the relationship between the expression of the estrogen receptor (ER), progestogen receptor (PR) and the biological characteristics of nasopharyngeal carcinoma (NPC). METHOD: The immuno-histochemical LSAB method was used to analyse the ER and PR in paraffin section specimen of 71 cases of nasopharyngeal carcinoma. CT scaning and clinic presentation were also put into consideration. RESULT: The expression of ER with (-), (+), (++) and (+++) in 71 cases were: 4(5.63%), 19(26.76%), 27(38.03%) and 21 (26.76%), respectively. The expression of PR with (-), (+) and (++) in 71 cases were: 41(57.75%), 29 (39.44%) and 2(2.82%), respectively. The encroaching of tumor to the tissue of parapharynx, the metastasis rate of lymphonode and clinic stage were related to the expression of ER (P < 0.01). The encroaching of tumor to the tissue of parapharynx, the metastasis rate of lymphonode were also assciated with the expression of PR (P < 0.05). CONCLUSION: NPC is a tumor of hightly expression of ER and PR. The positive intensity of ER and PR were associated with the encroaching extent of NPC, and the metastasis rate of lymphonode. It is significant to detarmine ER and PR of NPC in assessing the biological characterisitics of NPC and predicting the prognosis of NPC. It also suggests that the endocrine therapy can be put into consideration.

Adult↗
PubMed1999

[Regulation of cell cycle by retinoic acid in gastric cancer cells].

Retinoic acid can induce growth inhibition and apoptosis, and regulate cell cycle in many types of cancer cell lines. In this study, we investigated the role of all-trans retinoic acid (ATRA) and its mechanism of action in human gastric cancer cell lines. Our results demonstrated that ATRA effectively inhibited growth in three of four gastric cancer cell lines by induction of G0/G1 arrest, and did not induce apoptosis in four gastric cancer cell lines. In RA-sensitive cell lines, ATRA-induced G0/G1 arrest is associated with down regulaton of c-myc and hyperphosphorylated Rb expression, and up regulation of p21WAF1/CIP1 and p53 expression. There were no significant changes in cyclin D1 or CDK4 expression induced by ATRA. Futhermore, expression of these genes were not regulated by ATRA in ATRA-resistant gastric cancer cell line. These results indicate that growth inhibition, rather than apoptosis, is correlated with G0/G1 arrest of these cell lines, more important molecules related cell cycle, including c-myc, p21WAF1/CIP1, p53 and Rb, are involveed in regulation of cell cycle in gastric cancer cells.

Antineoplastic Agents↗
PubMed1999

[Effects of human thorax tissues on conduction of electrocardiogram and body surface potential].

In this paper, the forward problem of electrocardiogram(ECG) has been calculated by means of numerical simulating techniques. Firstly, It is focused on the effects of organs and tissues within the thorax on the body surface potentials under a 2-D cross section of thorax in terms of finite element method (FEM). To check the effect of skeletal muscle layers on ECG, the simulating computation of ECG, by a method combining FEM with boundary element method (BEM), has been carried out in terms of a 3-D thorax model.

Algorithms↗
PubMed1999

[Gene cloning and expression of Mycobacterium leprae alpha 2 antigen].

OBJECTIVES: The recombinant alpha 2 antigen of M. leprae was prepared using the molecular biologic tools and the recombinant DNA expression technology. METHODS: Screening of the M. leprae expression library was performed by the plaque hybridization technique. Nucleotide sequences were determined by dideoxy termination method. RESULTS: The gene coding for alpha 2 antigen of M. leprae was cloned and characterized, and the complete nucleotide sequence data has been assigned in the GSDB, DDBJ, EMBL and NCBI nucleotide sequence databank. The over expression system of alpha 2 antigen gene in E. coli was constructed, and the recombinant alpha 2 antigen has been purified by amylose column chromatography at the purity of more than 95%. More than 10 mg of recombinant alpha 2 antigen has been obtained from 200 ml of liquid culture. CONCLUSION: The recombinant alpha 2 antigen of M. leprae could be used as one of the specific antigens for the sero-diagnosis of leprosy.

Amino Acid Sequence↗
PubMed1999

[Identification of Panax quinquefolius, P. ginseng and P. notoginseng by protein fingerprints].

Establish the way of protein fingerprints to identify P. quinquefolius, P. ginseng and P. notoginseng of genus Panax by SDS-PAGE, Tris-tricine and Western blot. The fingerprints of Panax species from 28 KD to 58 KD and 55 KD are in common. Very different fingerprints of P. quinquefolius are found below 28 KD. The fingerprints above 58 KD seemed to be peculiar for P. ginseng. Hence the approach may be used as a means to authenticate the concerned Panax species, especially for identification of P. quinquefolius.

Blotting, Western↗
PubMed1999

[Investigation on preparation procedure for compound shenglin oral].

The optimum preparation procedure for compound Shenglin oral was studied by orthogonal test (including 5 factors: water-adding amount, decocting time, decocting times, concentrating scale, alcohol-precipitation concentration with 3 levels every factor). As a result, A1B1C3D1E1 is the procedure of choice: 24 times of water-adding amount, decocting 3 times, 1.5 hours of total decocting time, 0.8 g/ml of concentrating scale and 36% of alcohol-precipitation concentration.

Administration, Oral↗
PubMed1999

[The comparison between approximate entropy and complexity in the study of sleep EEG].

The Paper introduces two algorithms as a complexity measure. One is the algorithm defined by Kaspar and Schuster, the other is a recently developed statistic quantifying regularity and complexity--Approximate entropy (ApEn). They have been applied for the study of sleep EEG. According to the laboratory application and comparison, the result shows that ApEn is a valued complexity measure.

Algorithms↗
PubMed1999

[Study on the determination of iodine by ICP-AES].

A method for the determination of iodine in iodo-calcium pieces by ICP-AES was studied. I- was turned to I2 by HClO4 and H2O2. The detection limit of iodine is 1 ng/mL. The sample was dissolved with water and was directly determined without seperating the precipitate in the bottom of volume flask. It was found that the precipitate attracted with I2 and the quantity of attracting would increase with delay time.

Dietary Supplements↗
PubMed1998

Ser-262 in human recombinant tau protein is a markedly more favorable site for phosphorylation by CaMKII than PKA or PhK.

Several kinases have been shown to phosphorylate tau protein at Ser-262, an important site involved in the regulation of the binding of tau to microtubules. In this study we compared the phosphorylation of tau at Ser-262 by CaMKII, PhK and PKA in vitro as determined by radioimmunoblots developed by the monoclonal antibody 12E8 which recognizes P-Ser-262 and P-Ser-356; and Ab-262, a polyclonal antibody which is specific to unphosphorylated Ser-262 in tau. We found that the phosphorylation at Ser-262 was several times more effective by CaMKII than PKA or PhK. Employing rat brain extract as a source of all brain kinases and KN-62, a specific inhibitor of CaMKII, we found that CaMKII accounts for approximately 45% of phosphorylation at Ser-262. Furthermore, in rat brain slices kept metabolically active in oxygenated artificial CSF, phosphorylation of tau at Ser-262 was (i) increased up to 120% in the presence of bradykinin, a CaMKII activator, and (ii) inhibited by approximately 35% in the presence of KN-62. Thus, CaMKII is a major tau Ser-262 kinase in mammalian brain.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1998

Electrocatalytic reduction of S-nitrosoglutathione at electrodes modified with an electropolymerized film of a pyrrole-derived viologen system and their application to cellular S-nitrosoglutathione determinations.

The preparation, electrochemical characterization, and analytical applications of glassy carbon (GC) electrodes modified with electropolymerized films of the cation N,N'-di(3-pyrrol-1-yl-propyl)-4,4'-bipyridine (DPPB) are described. Electropolymerized films of DPPB on GC electrodes exhibit two one-electron redox processes centered at -0.45 and -0.85 V, respectively. S-Nitrosoglutathione (GSNO) can be electrocatalytically reduced at electrodes modified with electropolymerized films of DPPB at approximately -0.4 V vs sodium-saturated calomel electrode, which represents a dramatic diminution of about 600 mV in the overpotential in comparison with the reaction carried out at a bare GC electrode. The kinetics of the catalytic reaction have been characterized using cyclic voltammetry and rotated disk electrode techniques from which a value of (1.3 +/- 0.2) x 10(3)M-1 s-1 was obtained. Using electrodes modified with an electropolymerized film of DPPB we have carried out preliminary studies of the determination of intracellular GSNO concentrations in two strains of the bacterium Rhodobacter sphaeroides.

Electrochemistry↗
PubMed1998

Tau is phosphorylated by GSK-3 at several sites found in Alzheimer disease and its biological activity markedly inhibited only after it is prephosphorylated by A-kinase.

Alzheimer disease is characterized by a specific type of neuronal degeneration in which the microtubule associated protein tau is abnormally hyperphosphorylated causing the disruption of the microtubule network. We have found that the phosphorylation of human tau (tau3L) by A-kinase, GSK-3 or CK-1 inhibits its microtubule assembly-promoting and microtubule-binding activities. However, the inhibition of these activities of tau by GSK-3 is significantly increased if tau is prephosphorylated by A-kinase or CK-1. The most potent inhibition is observed by combination phosphorylation of tau with A-kinase and GSK-3. Under these conditions, only very few microtubules are seen by electron microscopy. Sequencing of 32P-labeled trypsin phosphopeptides from tau prephosphorylated by A-kinase (using unlabeled ATP) and further phosphorylated by GSK-3 in the presence of [gamma-32P]ATP revealed that Ser-195, Ser-198, Ser-199, Ser-202, Thr-205, Thr-231, Ser-235, Ser-262, Ser-356 and Ser-404 are phosphorylated, whereas if tau is not prephosphorylated by A-kinase, GSK-3 phosphorylates it at Thr-181, Ser-184, Ser-262, Ser-356 and Ser-400. These data suggest that (i) prephosphorylation of tau by A-kinase makes additional and different sites accessible for phosphorylation by GSK-3; (ii) phosphorylation of tau at these additional sites further inhibits the biological activity of tau in its ability to bind to microtubules and promote microtubule assembly. Thus a combined role of A-kinase and GSK-3 should be considered in Alzheimer neurofibrillary degeneration.

Alzheimer Disease↗
PubMed1998

Phosphorylation of tau at both Thr 231 and Ser 262 is required for maximal inhibition of its binding to microtubules.

The paired helical filaments (PHFs) found in Alzheimer's disease (AD) brains are composed primarily of the microtubule-associated protein tau. PHF-tau is in a hyperphosphorylated state and is unable to promote microtubule assembly. We investigated whether the inhibition of tau binding to microtubules is increased when tau is phosphorylated by different kinases in combination with GSK-3. We found that when tau was first phosphorylated by A-kinase, C-kinase, cdk5, or CaM kinase II and then by GSK-3, its binding to microtubules was inhibited by 45, 61, 78, and 79%, respectively. Further, the kinase combinations cdk5/GSK-3 and CaM kinase II/GSK-3 rapidly phosphorylated the sites Thr 231 and Ser 235. When these sites were individually replaced by Ala and the phosphorylation experiments repeated, tau binding to microtubules was inhibited by 54 and 71%, respectively. By comparison, when Ser 262 was replaced by Ala, tau binding to microtubules was inhibited by only 8% after phosphorylation by CaM kinase II. From these observations we estimate that the phosphorylation of Thr 231, Ser 235, and Ser 262 contributes approximately 26, approximately 9, and approximately 33%, respectively, of the overall inhibition of tau binding to microtubules. Together, our results indicate that the binding of tau to microtubules is controlled by the phosphorylation of several sites, among which are Thr 231, Ser 235, and Ser 262.

Amino Acid Sequence↗
PubMed1998

A comparison of three stereotactic radiotherapy techniques; ARCS vs. noncoplanar fixed fields vs. intensity modulation.

PURPOSE: Linac arc based stereotactic radiotherapy is being used with increasing frequency to treat brain tumors. This approach can be used for single or fractionated treatments, and is typically carried out with circular collimators which are optimal for small, spherical targets. Treatment planning using fixed noncoplanar beams or intensity-modulated beams may enhance the ability to conform to irregularly shaped and/or large tumors, especially when combined with stereotactic localization. We compare the dose conformity and normal brain dose characteristics of three stereotactic techniques for various nonspherical target shapes. METHODS AND MATERIALS: Three intracranial test targets were constructed using a 3D treatment planning system after a patient underwent CT simulation. The targets included an ellipsoid with major axis dimensions of 4.0, 2.0, and 2.0 cm, a hemisphere with a diameter of 4.0 cm, and an irregularly shaped patient tumor with a maximum dimension of 5.3 cm. The following stereotactic techniques were compared for each target: a) 5 arcs as used in traditional linac radiosurgery/radiotherapy (noncoplanar arcs [ARCS]), b) 6 fixed noncoplanar custom blocked fields (3D), c) intensity modulation using 6 noncoplanar beams and a mini-multileaf collimator (intensity-modulated radiation therapy [IMRTI). Dose volume histograms were performed for each target/technique combination. RESULTS: For the ellipsoid, dose conformity is similar for all three techniques and normal brain isodose distributions are more favorable with the ARCS plan. For the hemisphere and irregular tumor targets, dose conformity and high/low isodose normal brain volumes are more favorable with the IMRT technique. CONCLUSIONS: For the targets described above, the intensity-modulated technique results in improved dose conformity and decreased dose to nontarget brain in high and low isodose regions as compared to the standard noncoplanar arc technique or noncoplanar fixed fields for the hemisphere and tumor targets. Intensity-modulated treatment delivery may allow for an increase in the therapeutic ratio for treating stereotactically defined large and/or irregularly shaped intracranial targets.

Brain Neoplasms↗
PubMed1998

Identification of the domains of photoincorporation of the 3'- and 7-benzophenone analogues of taxol in the carboxyl-terminal half of murine mdr1b P-glycoprotein.

P-glycoprotein is an ATP-dependent drug-efflux pump that can transport a diverse range of structurally and functionally unrelated hydrophobic compounds across the plasma membrane. The transporter is composed of two homologous halves, each containing a nucleotide binding fold and six putative transmembrane spanning segments. The contact domains between the murine mdr1b P-glycoprotein and two photoreactive Taxol analogues have been mapped by a combination of CNBr digestion and immunoprecipitation studies. We had demonstrated previously that the 3'-p-benzoyldihydrocinnamoyl (BzDC) analogue of Taxol specifically photolabeled mdr1b P-glycoprotein and now show that the corresponding C-7 analogue likewise specifically photoincorporates into the transporter. CNBr digestion of both photolabeled P-glycoproteins gave rise to an approximate 10 kDa tritium-labeled peptide, each of which was a distinct polypeptide. The CNBr fragment generated from the 3'-BzDC-Taxol-photolabeled P-glycoprotein was immunoprecipitated by a polyclonal antibody (Ab7) raised against amino acid residues 1008-1019 of the mdr1b isoform. In contrast, the CNBr fragment generated from the 7-BzDC-Taxol-photolabeled P-glycoprotein was immunoprecipitated by a polyclonal antibody (Ab4) raised against amino acid residues 740-750. The specificity of these reactions was demonstrated by showing that the presence of the appropriate synthetic peptide blocked the immunoprecipitation. Moreover when the antibodies were reversed, no immunoprecipitation occurred. Based on the deduced amino acid sequence of mdr1b P-glycoprotein, and its hydropathy plot analysis, our data indicated that the 3'-BzDC group photoincorporates into amino acid residues 985-1088, a region of the transporter that includes half of TM 12 and terminates just after the Walker A motif in the second nucleotide binding fold. The 7-BzDC group photoincorporates into amino acid residues 683-760, a region of the transporter that includes all of TM 7 and half of TM 8 plus the intervening extracellular loop.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Incomplete embryonic lethality and fatal neonatal hemorrhage caused by prothrombin deficiency in mice.

Deficiency of blood coagulation factor V or tissue factor causes the death of mouse embryos by 10.5 days of gestation, suggesting that part of the blood coagulation system is necessary for development. This function is proposed to require either generation of the serine protease thrombin and cell signaling through protease-activated receptors or an activity of tissue factor that is distinct from blood clotting. We find that murine deficiency of prothrombin clotting factor 2 (Cf2) was associated with the death of approximately 50% of Cf2(-/-) embryos by embryonic day 10.5 (E10.5), and surviving embryos had characteristic defects in yolk sac vasculature. Most of the remaining Cf2(-/-) embryos died by E15.5, but those surviving to E18.5 appeared normal. The rare Cf2(-/-) neonates died of hemorrhage on the first postnatal day. These studies suggest that a part of the blood coagulation system is adapted to perform a developmental function. Other mouse models show that the absence of platelets or of fibrinogen does not cause fetal wastage. Therefore, the role of thrombin in development may be independent of its effects on blood coagulation and instead may involve signal transduction on cells other than platelets.

Animals↗