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Chang LJ, Huang DJ, Li WH, Cheong SW, Ratcliff W, Lynn JW. Crossover from incommensurate to commensurate magnetic orderings in CoCr(2)O(4). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:456008. [PMID: 21694028 DOI: 10.1088/0953-8984/21/45/456008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The conical spin order of multiferroic CoCr(2)O(4) has been studied by a neutron diffraction to investigate its magnetic phase transitions at temperatures below 40 K. Magnetic order of a spiral spin component with an incommensurate propagation vector of (0.63, 0.63, 0) was observed at 26 K, while at 14.5 K, the incommensurate conical spin order showed a transition into the fixed commensurate propagation vector of (2/3,2/3,0). In addition, two satellite peaks with propagation vectors of (0.035, 0, 0) and (0, 0.035, 0) from the commensurate vector were observed. The widths of these peaks indicate a long-range magnetic order. This new magnetic configuration below 14.5 K may lead to a new model of multiferroic behavior differing from the well-known spin-current model for magnetic ferroelectricity.
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Choi YJ, Okamoto J, Huang DJ, Chao KS, Lin HJ, Chen CT, van Veenendaal M, Kaplan TA, Cheong SW. Thermally or magnetically induced polarization reversal in the Multiferroic CoCr2O4. PHYSICAL REVIEW LETTERS 2009; 102:067601. [PMID: 19257633 DOI: 10.1103/physrevlett.102.067601] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Indexed: 05/27/2023]
Abstract
We report the unexpected evolution, with thermal and magnetic-field (H) variations, of the interrelation between the polarization P, magnetization M, and spiral wave vector Q in CoCr2O4, which has a ferrimagnetic conical-spiral magnetic order. For example, P suddenly jumps and changes its sign at the magnetic lock-in transition (T_{L}) with thermal variation, or with isothermal variation of H (without changing its direction) at T_{L}, which surprisingly occurs without change in spiral handedness (i.e., the sign of Q). The presence of multiple spiral sublattices may be behind this unusual behavior.
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Wyler S, Huang DJ, Singer G, Schötzau A, Holzgreve W, Güth U. Metastatic involvement of the urinary tract in patients with advanced ovarian carcinoma: lessons from the autopsy for an interdisciplinary treatment approach. EUR J GYNAECOL ONCOL 2009; 30:174-177. [PMID: 19480248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
PURPOSE OF INVESTIGATION Frequency and extent of metastases in urologic organs found at autopsy of ovarian carcinoma patients were evaluated. METHODS Autopsy reports from 170 patients who died of advanced ovarian carcinoma between 1975 and 2005 were studied. The distribution of abdominal metastatic sites with particular attention to the involvement of the urologic organs, and hydronephrosis was analyzed. RESULTS The distribution of metastatic sites was as follows: kidney (n = 6, 3.5%), urinary bladder (n = 38, 22.4%), and ureter (n = 20, 11.8%). In 36 patients, hydronephrosis was observed (21.2%); of these patients, 20 (55.6%) also had ureteral involvement. All patients with ureteral involvement had hydronephrosis. CONCLUSION Hydronephrosis in late stages of ovarian carcinoma, usually attributed to extrinsic compression of the ureter by an abdominal tumor, may also be explained by ureteral metastases. This fact must be considered in the clinical management of these patients, particularly in the restoration of luminal patency through an endoscopically placed internal ureteral stent.
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Güth U, Huang DJ, Schötzau A, Zanetti-Dällenbach R, Holzgreve W, Bitzer J, Wight E. Target and reality of adjuvant endocrine therapy in postmenopausal patients with invasive breast cancer. Br J Cancer 2008; 99:428-33. [PMID: 18665168 PMCID: PMC2527804 DOI: 10.1038/sj.bjc.6604525] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Previous research evaluating the use of adjuvant endocrine therapy among postmenopausal breast cancer patients showed with 15–50% wide ranges of non-adherence rates. We evaluated this issue by analysing an unselected study group comprising of 325 postmenopausal women, diagnosed from 1997 to 2003 with hormonal receptor-positive invasive breast cancer. The different clinical situations that led to the discontinuation of adjuvant endocrine therapy were clearly defined and differentiated: non-adherence was not simply the act of stopping medication, but rather the manifestation of an intentional behaviour of the patient. Of the 287 patients who initiated endocrine therapy, 191 (66.6%) fully completed this treatment. Thirty-one patients (10.8%) showed non-adherence to therapy. Patients who had follow-up with a general practitioner, rather than in an oncologic unit, were more likely to be non-adherent (P=0.0088). Of 25 patients who changed medication due to therapy-related adverse effects, 20 (80%) patients fully completed the therapy after drug change. In adjuvant endocrine therapy, a lowering of the non-adherence rate to 10.8%, the lowest reported in the literature, is realistic when patients are cared for by a specialised oncologic unit focusing on the individual needs of the patients.
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Huang SW, Huang DJ, Okamoto J, Mou CY, Wu WB, Yeh KW, Chen CL, Wu MK, Hsu HC, Chou FC, Chen CT. Magnetic ground state and transition of a quantum multiferroic LiCu2O2. PHYSICAL REVIEW LETTERS 2008; 101:077205. [PMID: 18764576 DOI: 10.1103/physrevlett.101.077205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Indexed: 05/26/2023]
Abstract
Based on resonant soft x-ray magnetic scattering, we report that LiCu2O2 exhibits a large interchain coupling which suppresses quantum fluctuations along spin chains, and a quasi-2D short-range magnetic order prevails at temperatures above the magnetic transition. These observations unravel the fact that the ground state of LiCu2O2 possesses long-range 2D-like incommensurate magnetic order rather than being a gapped spin liquid as expected from the nature of quantum spin-1/2 chains. In addition, the spin coupling along the c axis is found to be essential for inducing electric polarization.
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Zhong XY, Holzgreve W, Huang DJ. Isolation of cell-free RNA from maternal plasma. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2008; 444:269-73. [PMID: 18425488 DOI: 10.1007/978-1-59745-066-9_21] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The discovery of cell-free RNA in plasma and serum samples provides possibilities for noninvasive prenatal diagnosis. Quantitative alterations of cell-free placental-derived mRNA in the maternal circulation are associated with many pregnancy-related disorders, such as preeclampsia and preterm labor. Obtaining circulating cell-free RNA is the first and often the most critical step for analyzing the placental-derived mRNA in maternal blood. We have compared different protocols for the extraction of cell-free RNA from plasma samples, and we have found the protocol using TRIzol LS reagent (Invitrogen) as lysis buffer combined with RNeasy Mini kit (QIAGEN) to be the optimal method for extracting high-quality cell-free RNA in the highest quantities possible. This method is also amenable to the simultaneous extraction of cell-free RNA from many different samples, by use of the QIAGEN Vacuum Manifold QIAvac 24 Plus.
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Huang DJ, Mergenthaler-Gatfield S, Hahn S, Holzgreve W, Zhong XY. Isolation of cell-free DNA from maternal plasma using manual and automated systems. Methods Mol Biol 2008; 444:203-208. [PMID: 18425482 DOI: 10.1007/978-1-59745-066-9_15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Cell-free fetal DNA present in the maternal circulation holds great potential for noninvasive prenatal diagnosis and analysis of fetal genetic traits. However, only approximately 3-6% of total DNA in the maternal plasma is of fetal origin. Because of its scarcity in the maternal circulation, various methods have been developed and tested to optimize the extraction of this rare material from plasma. Here, we first describe the commonly used protocol for separating plasma from whole blood samples. We also describe two commercially available methods for the extraction of cell-free DNA from maternal plasma, which we have found particularly straightforward and easy to use: a manual method using the High Pure PCR Template Preparation kit (Roche Diagnostics) and an automated system using the MagNA Pure LC instrument (Roche Diagnostics). Use of the methods described here will help to ensure maximum yield and purity of cell-free fetal DNA extracted from maternal plasma samples for downstream analyses.
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Huang DJ, Zhang YM, Song G, Long J, Liu JH, Ji WH. Contaminants-induced oxidative damage on the carp Cyprinus carpio collected from the upper Yellow River, China. ENVIRONMENTAL MONITORING AND ASSESSMENT 2007; 128:483-8. [PMID: 17180433 DOI: 10.1007/s10661-006-9341-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2005] [Accepted: 06/14/2006] [Indexed: 05/13/2023]
Abstract
The Yellow River, the second largest river in China, is the most important resource of water supply in North China. In the last 40 years, even in the upper Yellow River, with the development of industry and agriculture, more and more contaminants have been discharged into this river and greatly polluted the water. Although a routine chemical component analysis has been performed, little is known about the real toxic effects of the polluted water on organisms at environmental level. To explore whether the pollutants induced oxidative stress and damage to aquatic organisms, malondialdehyde (MDA) level and activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) in hepatopancreas, kidney and intestine of the field-collected carp Cyprinus carpio from a mixed polluted (Lanzhou Region, LZR) and a relatively unpolluted (Liujiaxia Region, LJXR) sites of the upper Yellow River were measured. The results showed that when the values of LZR compared with those of LJXR, SOD and GST activities increased and GPx activity decreased significantly in all the three organs (P < 0.05-0.01); CAT activity decreased but MDA level increased significantly (P < 0.05-0.01) only in kidney and intestine. In conclusion, the results of this study suggest that the pollutants can induce obvious oxidative damage in the carp, and the SOD, GST and GPx might be better indicators for the oxidative damage in aquatic organisms.
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Okamoto J, Huang DJ, Mou CY, Chao KS, Lin HJ, Park S, Cheong SW, Chen CT. Symmetry of multiferroicity in a frustrated magnet TbMn2O5. PHYSICAL REVIEW LETTERS 2007; 98:157202. [PMID: 17501376 DOI: 10.1103/physrevlett.98.157202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Indexed: 05/15/2023]
Abstract
Based on measurements of soft-x-ray magnetic scattering and symmetry considerations, we demonstrate that the magnetoelectric effect in TbMn2O5 arises from an internal field determined by S-->q--> x S-->-q--> with S-->q--> being the magnetization at modulation vector q-->, whereas the magnetoelastic effect in the exchange energy governs the response to external electric fields. Our results set fundamental symmetry constraints on the microscopic mechanism of multiferroicity in frustrated magnets.
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Huang DJ, Zimmermann BG, Holzgreve W, Hahn S. Improvement of methods for the isolation of cell-free fetal DNA from maternal plasma: comparison of a manual and an automated method. Ann N Y Acad Sci 2007; 1075:308-12. [PMID: 17108225 DOI: 10.1196/annals.1368.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The low amount of cell-free fetal DNA present in the maternal circulation poses significant challenges to its use in future diagnostic applications, and ways of increasing the yield of this potential marker extracted from maternal plasma are constantly being explored. In this study, we compared two methods of DNA extraction, a manual and an automated method. Our analysis revealed that although the manual method yielded overall more total cell-free DNA, the automated system yielded higher quantities of cell-free DNA of fetal origin. Furthermore, the DNA isolated using the automated system appeared to be of greater purity than that isolated by the manual method, with fewer inhibitors to downstream real-time PCR reactions.
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Huang DJ, Nelson MR, Zimmermann B, Dudarewicz L, Wenzel F, Spiegel R, Nagy B, Holzgreve W, Hahn S. Reliable detection of Trisomy 21 using MALDI-TOF mass spectrometry. Genet Med 2006; 8:728-34. [PMID: 17108765 DOI: 10.1097/01.gim.0000245573.42908.34] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE Current diagnostic methods for chromosomal abnormalities rely mainly on karyotyping and occasionally fluorescent in situ hybridization or quantitative polymerase chain reaction. We describe an alternative molecular method for the detection of trisomy 21 involving mass spectrometric analysis of single nucleotide polymorphisms. METHODS In collaboration with Sequenom, Inc., 350 blinded amniotic fluid, amniocyte culture, chorionic villus, or amniotic fluid supernatant samples were analyzed for trisomy 21 using SNP analysis and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Peak ratios were calculated for heterozygous genotypes and compared to control values generated from known euploid samples. An analytical algorithm using standard deviations from control values was used to determine the probability of a sample being affected or unaffected. RESULTS Seventy-three trisomy 21 samples from among the 350 blinded samples were correctly identified. There were no false-positive or false-negative results among the complete trisomy 21 samples. One sample exhibiting mosaicism for trisomy 21 was identified as being unaffected. CONCLUSIONS MALDI-TOF mass spectrometry is a robust and reproducible method for the detection of trisomy 21. Its amenability to high-throughput analysis and high degree of multiplexing make it a potential future diagnostic tool for the detection of other aneuploidies as well.
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Huang DJ, Lin HJ, Okamoto J, Chao KS, Jeng HT, Guo GY, Hsu CH, Huang CM, Ling DC, Wu WB, Yang CS, Chen CT. Charge-orbital ordering and Verwey transition in magnetite measured by resonant soft X-ray scattering. PHYSICAL REVIEW LETTERS 2006; 96:096401. [PMID: 16606287 DOI: 10.1103/physrevlett.96.096401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Indexed: 05/08/2023]
Abstract
We report experimental evidence for the charge-orbital ordering in magnetite below the Verwey transition temperature T(V). Measurements of O K-edge resonant x-ray scattering on magnetite reveal that the O 2p states in the vicinity of the Fermi level exhibit a charge-orbital ordering along the c axis with a spatial periodicity of the doubled lattice parameter of the undistorted cubic phase. Such a charge-orbital ordering vanishes abruptly above T(V) and exhibits a thermal hysteresis, correlating closely with the Verwey transition in magnetite.
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Zhang YM, Huang DJ, Wang YQ, Liu JH, Yu RL, Long J. Heavy metal accumulation and tissue damage in goldfish Carassius auratus. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2005; 75:1191-9. [PMID: 16402311 DOI: 10.1007/s00128-005-0875-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2005] [Accepted: 10/05/2005] [Indexed: 05/06/2023]
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Huang DJ, Zimmermann BG, Holzgreve W, Hahn S. Use of an Automated Method Improves the Yield and Quality of Cell-Free Fetal DNA Extracted from Maternal Plasma. Clin Chem 2005; 51:2419-20. [PMID: 16306116 DOI: 10.1373/clinchem.2005.056010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Wu WB, Huang DJ, Okamoto J, Tanaka A, Lin HJ, Chou FC, Fujimori A, Chen CT. Orbital symmetry and electron correlation in NaxCoO2. PHYSICAL REVIEW LETTERS 2005; 94:146402. [PMID: 15904085 DOI: 10.1103/physrevlett.94.146402] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2004] [Indexed: 05/02/2023]
Abstract
Measurements of polarization-dependent soft x-ray absorption reveal that the electronic states determining the low-energy excitations of NaxCoO2 have predominantly a(1g) symmetry with significant O 2p character. In contrast to the prediction of band theory, doping-dependent O 1s x-ray absorption shows a large transfer of spectral weight, providing spectral evidence for strong electron correlations of the layered cobaltates. We also found that NaxCoO2 exhibits a charge-transfer electronic character rather than a Mott-Hubbard character.
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Jeng HT, Guo GY, Huang DJ. Charge-orbital ordering and Verwey transition in magnetite. PHYSICAL REVIEW LETTERS 2004; 93:156403. [PMID: 15524911 DOI: 10.1103/physrevlett.93.156403] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Indexed: 05/12/2023]
Abstract
Local density approximation + Hubbard U (LDA + U) band structure calculations reveal that magnetite (Fe3O4) forms an insulating charge-orbital-ordered state below the Verwey transition temperature. The calculated charge ordering is in good agreement with that inferred from recent experiments. We found an associated t(2g) orbital ordering on the octahedral Fe2+ sublattice. Such an orbital ordering results primarily from the on-site Coulomb interaction. This finding unravels such fundamental issues about the Verwey transition as the mechanism for the charge ordering and for the formation of the insulating gap, as well as the nonobedience of the Anderson's criterion for the charge ordering.
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Huang DJ, Chang CF, Jeng HT, Guo GY, Lin HJ, Wu WB, Ku HC, Fujimori A, Takahashi Y, Chen CT. Spin and orbital magnetic moments of Fe3O4. PHYSICAL REVIEW LETTERS 2004; 93:077204. [PMID: 15324271 DOI: 10.1103/physrevlett.93.077204] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Indexed: 05/24/2023]
Abstract
We present measurements of the spin and orbital magnetic moments of Fe3O4 by using SQUID and magnetic circular dichroism in soft x-ray absorption. The measurements show that Fe3O4 has a noninteger spin moment, in contrast to its predicted half-metallic feature. Fe3O4 also exhibits a large unquenched orbital moment. Calculations using the local density approximation including the Hubbard U method and the configuration interaction cluster-model suggest that strong correlations and spin-orbit interaction of the 3d electrons result in the noninteger spin and large orbital moments of Fe3O4.
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Huang DJ, Wu WB, Guo GY, Lin HJ, Hou TY, Chang CF, Chen CT, Fujimori A, Kimura T, Huang HB, Tanaka A, Jo T. Orbital ordering in La0.5Sr1.5MnO4 studied by soft X-ray linear dichroism. PHYSICAL REVIEW LETTERS 2004; 92:087202. [PMID: 14995808 DOI: 10.1103/physrevlett.92.087202] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2003] [Revised: 11/17/2003] [Indexed: 05/24/2023]
Abstract
We found that the conventional model of orbital-ordering of 3x(2)-r(2)/3y(2)-r(2) type in the e(g) states of La0.5Sr1.5MnO4 is incompatible with measurements of linear dichroism in the Mn 2p-edge x-ray absorption, whereas these e(g) states exhibit predominantly cross-type orbital ordering of x(2)-z(2)/y(2)-z(2). LDA+U band-structure calculations reveal that such a cross-type orbital-ordering results from a combined effect of antiferromagnetic structure, Jahn-Teller distortion, and on-site Coulomb interactions.
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Li HL, Huang DJ, Zhang XJ, Zhao Q, Wan AJ. [Effects of insulin on production of NO and NOS mRNA expression in bovine aortic endothelial cells]. ZHONGGUO YING YONG SHENG LI XUE ZA ZHI = ZHONGGUO YINGYONG SHENGLIXUE ZAZHI = CHINESE JOURNAL OF APPLIED PHYSIOLOGY 2001; 17:37-39. [PMID: 21171439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
AIM In order to explore the regulation of the production of nitric oxide (NO) and the expression of nitric oxide synthase (NOS) gene in bovine aortic endothelial cells (BAEC) by insulin. METHODS The NO2- which is the production of NO in the culture medium was determined based on Griess reaction. Quantitative RT/PCR technique was performed to quantitate the levels of NOS mRNA in BAEC. RESULTS (1) Insulin neither affected BAEC proliferation, nor had cytotoxic effect. (2) Over a concentration range of 1-15 microg/ ml, insulin stimulation of BAEC resulted in a dose-dependent production of NO in the culture supernatants 2 hours later, with a maximum at 12 hours and this effect was completely blocked by L-NAME. (3) NOS mRNA was slightly greater in BAEC after exposed to insulin, but without statistical significance. CONCLUSION Since the endothelial cell proliferation and the expression of NOS mRNA was not affected with insulin, our data suggested that the insulin-induced NO production was mediated via the activation of NOS activity.
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Wang HL, Lee PD, Chen WL, Huang DJ, Su JC. Osmotic stress-induced changes of sucrose metabolism in cultured sweet potato cells. JOURNAL OF EXPERIMENTAL BOTANY 2000; 51:1991-1999. [PMID: 11141173 DOI: 10.1093/jexbot/51.353.1991] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The intra- and extracellular sugar contents, the activities of sucrose-metabolizing enzymes, and the metabolism of [U-(14)C] glucose in a pulse-chase experiment were compared between the normal and osmotically stressed (by 0.6 M sorbitol) sweet potato (Ipomoea batatas) suspension cells. The stress enhanced the levels of sucrose and sucrose phosphate synthase (SPS) activity. Northern blot analysis also showed that prolonged osmotic stress enhanced the SPS gene expression at the transcriptional level. Stressed cells also had higher activities of sucrose cleaving enzymes, such as alkaline invertase and sucrose synthase. The (14)C-sucrose isolated from normal and stressed cells had (14)C-fructose and (14)C-glucose ratios of 0.68 and 1, respectively. These data suggest the continual cycling of degradation and synthesis of sucrose in both types of cells. Among the enzymes used in constructing such futile cycling, besides invertase and SPS, sucrose synthase (SS) should be involved in normal cells, but not in stressed ones. It is apparent that the osmotic stress caused a significant change in the pattern of sucrose metabolism.
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Abstract
Oxabenzonorbornadienes 1 and 2 and azabenzonorbornadiene 3 undergo [2+2] cycloaddition with alkynes (PhC triple bond Ph, PhC triple bond CMe, PhC triple bond CCO2Et, PhC triple bond CCH(OEt)2, and HC triple bond C(CH2)4Me) in the presence of [Ni(PPh3)2Cl2], PPh3, and Zn powder in toluene to afford the corresponding exo-cyclobutene derivatives 4a-e, 5a-e, and 6 in fair to excellent yields. Under similar conditions. EtCO2C triple bond CCO2Et does not react with 1 in toluene to give the [2+2] cycloaddition product, but in acetonitrile, the catalytic [2+2] cycloaddition proceeds and cycloadduct 4 f is isolated in 83% yield. At high temperature, these cyclobutene derivatives readily undergo ring expansion to yield the corresponding 8-membered carbocyclic dienes. Thus, flash vacuum pyrolysis of 4a, 4d, 4f, 6, and 14 at 500 degrees C affords dienes 13a-d and 15 in 70-96% yields. This interesting ring expansion may be viewed as the insertion of an alkyne moiety into the carbon-carbon double bond of a cyclic olefin resulting in the enlargement of the ring by two carbons. Compound 13a is readily deoxygenated by TiCl4 and Zn in THF to give a cyclooctatetraene derivative 16 in 89% yield.
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Horvath DM, Huang DJ, Chua NH. Four classes of salicylate-induced tobacco genes. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 1998; 11:895-905. [PMID: 9725022 DOI: 10.1094/mpmi.1998.11.9.895] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We have identified and characterized fragments of 15 salicylic acid (SA) early response genes. The kinetics of induction and response to cycloheximide (CHX) treatment allowed classification of genes into four groups. Classes I-III are characterized by immediate-early responses, showing increased accumulation of mRNA within 30 min of SA treatment. Moreover, CHX did not block induction of these genes, indicating that latent cellular factors mediate the SA response. Class IV genes were induced more slowly, but still within 2 to 3 h of SA treatment, and required protein synthesis for expression. Although identified in this study as SA-responsive genes, several could also be induced by other compounds. Two genes were characterized in more detail, including isolation of cDNA sequences and additional analysis of gene expression. Sequence analysis revealed that the class I gene, C18-1, is the previously identified ethylene response element binding protein 1 (EREBP1), an ethylene-induced transcription factor for basic pathogenesis-related (PR) genes, whereas the class III gene, G8-1, is a novel sequence. G8-1 was found to be strongly induced only by SA and its active analogs and was exquisitely sensitive to low SA concentrations. These and other genes were found to be activated at early times following tobacco mosaic virus infection of resistant tobacco genotypes.
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Huang DJ, Johnson PD, Shi X. Quantum-well states and the short period of oscillation in Cu/Co(001) multilayers. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:17123-17127. [PMID: 9985847 DOI: 10.1103/physrevb.54.17123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Huang DJ, Riffe DM, Erskine JL. Simultaneous determination of Fe 3p spin-orbit and exchange splittings in photoemission. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:15170-15179. [PMID: 9978471 DOI: 10.1103/physrevb.51.15170] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Lee J, Huang DJ, Erskine JL. Forward-electron-scattering study of the surface structure and phase transition on W(001). PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:13824-13827. [PMID: 9978197 DOI: 10.1103/physrevb.51.13824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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