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Zhang L, Cao DY, Wang J, Xiang B, Dun JN, Fang Y, Xue GQ. PEG-coated irinotecan cationic liposomes improve the therapeutic efficacy of breast cancer in animals. EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES 2013; 17:3347-3361. [PMID: 24379067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
BACKGROUND Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death among females owing. AIM This study aimed to construct a kind of PEG-coated irinotecan cationic liposomes for investigating its efficacy and mechanism of action in the treatment of breast cancer in preclinical models. MATERIALS AND METHODS Evaluations were performed on the MDA-MB231 breast cancer cells, the xenografted MDA-MB231 cancer cells in Female nude mice and Sprague-Dawley (SD) rat. The liposomes were characterized through assays of cytotoxicity, intracellular uptake, nuclei morphology, antitumor activities, pharmacokinetics and tissue distribution. RESULTS The zeta potential of PEG-coated irinotecan cationic liposomes was approximately 23 mV. The PEG-coated irinotecan cationic liposomes were approximately 66nm in diameter, significantly increased the intracellular uptake of irinotecan, and showed strong inhibitory effect on MDA-MB231 breast cancer cells. A significant antitumor efficacy in the xenografted MDA-MB231 breast cancer cells in nude mice was evidenced by intravenous administration of PEG-coated irinotecan cationic liposomes. PEG-coated irinotecan cationic liposomes also improved the irinotecan blood circulation time and showed an enhanced drug concentration in tumor. CONCLUSIONS PEG-coated irinotecan cationic liposomes had significant inhibitory effect against breast cancer in vitro and in vivo, hence providing a new strategy for treating breast cancer.
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Chi C, Xiang B, Deng J, Liu H, Lin F, Freed D, Arora R, Tian G. Therapeutic Effects of Human Mediastinal Adipose-Derived Stem Cells for Treatment of Myocardial Infarction in Rats. Can J Cardiol 2013. [DOI: 10.1016/j.cjca.2013.07.645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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White C, Mundt P, Li Y, Hasanally D, Xiang B, Klein J, Lee T, Arora R, Ravandi A, Tian G, Freed D. A Donor Whole Blood-Based Perfusate Provides Superior Preservation of Myocardial Function During Ex Vivo Heart Perfusion. Can J Cardiol 2013. [DOI: 10.1016/j.cjca.2013.07.644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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White C, Ali A, Hasanally D, Wang F, Xiang B, Mundt P, Large S, Ravandi A, Lee T, Arora R, Tian G, Freed D. Right Ventricular Distension in Donor Hearts Following Cardiocirculatory Death: Implications for Post-Transplant Function. J Heart Lung Transplant 2013. [DOI: 10.1016/j.healun.2013.01.1003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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White C, Xiang B, Mundt P, Arora R, Tian G, Freed D. Ex Vivo Heart Preservation: Impact of an Acellular Hemoglobin-Based Oxygen Carrier on Myocardial Function and Energy Metabolism. J Heart Lung Transplant 2013. [DOI: 10.1016/j.healun.2013.01.1004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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White C, Ali A, Xiang B, Colah S, Mundt P, Arora R, Lee T, Large S, Tian G, Freed D. 206 A Normokalemic Non-depolarizing Cardioplegia Minimizes Myocardial Injury And Improves Cardiac Function In A Large Animal Model Of Donation After Cardio-circulatory Death. Can J Cardiol 2012. [DOI: 10.1016/j.cjca.2012.07.203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Feng K, Pan C, Zhang G, Luo T, Zhao Z, Chen Y, Feng Y, Ye X, Hu G, He K, Niu R, Li Z, Wang P, Xiang B, Zhang L, Wang Q, Zhao F, Cao Q, Wang F, Yuan T, Zheng G, Liu Y, Zhong Y, Zhang M. Progress on design and R&D for helium-cooled ceramic breeder TBM in China. FUSION ENGINEERING AND DESIGN 2012. [DOI: 10.1016/j.fusengdes.2012.02.098] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Pollack IB, Ryerson TB, Trainer M, Parrish DD, Andrews AE, Atlas EL, Blake DR, Brown SS, Commane R, Daube BC, de Gouw JA, Dubé WP, Flynn J, Frost GJ, Gilman JB, Grossberg N, Holloway JS, Kofler J, Kort EA, Kuster WC, Lang PM, Lefer B, Lueb RA, Neuman JA, Nowak JB, Novelli PC, Peischl J, Perring AE, Roberts JM, Santoni G, Schwarz JP, Spackman JR, Wagner NL, Warneke C, Washenfelder RA, Wofsy SC, Xiang B. Airborne and ground-based observations of a weekend effect in ozone, precursors, and oxidation products in the California South Coast Air Basin. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd016772] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Xiang B. P-1328 - Genome-wide association analysis with brain structure measures as a quantitative phenotype for first-episode schizophrenia. Eur Psychiatry 2012. [DOI: 10.1016/s0924-9338(12)75495-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Ali AA, White P, Xiang B, Lin HY, Tsui SS, Ashley E, Lee TW, Klein JRH, Kumar K, Arora RC, Large SR, Tian G, Freed DH. Hearts from DCD donors display acceptable biventricular function after heart transplantation in pigs. Am J Transplant 2011; 11:1621-32. [PMID: 21749639 DOI: 10.1111/j.1600-6143.2011.03622.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cardiac transplantation is in decline, in contrast to other solid organs where the number of solid organ transplants from donors after circulatory death (DCD) is increasing. Hearts from DCD donors are not currently utilized due to concerns that they may suffer irreversible cardiac injury with resultant poor graft function. Using a large animal model, we tested the hypothesis that hearts from DCD donors would be suitable for transplantation. Donor pigs were subjected to hypoxic cardiac arrest (DCD) followed by 15 min of warm ischemia and resuscitation on cardiopulmonary bypass, or brainstem death (BSD) via intracerebral balloon inflation. Cardiac function was assessed through load-independent measures and magnetic resonance imaging and spectroscopy. After resuscitation, DCD hearts had near normal contractility, although stroke volume was reduced, comparable to BSD hearts. DCD hearts had a significant decline in phosphocreatine and increase in inorganic phosphate during the hypoxic period, with a return to baseline levels after reperfusion. After transplantation, cardiac function was comparable between BSD and DCD groups. Therefore, in a large animal model, the DCD heart maintains viability and recovers function similar to that of the BSD heart and may be suitable for clinical transplantation. Further study is warranted on optimal reperfusion strategies.
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Geng Y, Zhang M, Yuan W, Xiang B. Modified dispersive liquid–liquid microextraction followed by high-performance liquid chromatography for the determination of clenbuterol in swine urine. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2011; 28:1006-12. [DOI: 10.1080/19440049.2011.576444] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ali A, White P, Xiang B, Arora R, Lee T, Ashley E, Large S, Tian G, Freed D. 348 Hearts from DCD Donors Display Excellent Biventricular Function Following Transplantation. J Heart Lung Transplant 2011. [DOI: 10.1016/j.healun.2011.01.355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Ali A, Xiang B, Colah S, Mundt P, Arora R, Large S, Tian G, Freed D. 590 Evaluation of Load-Independent Biventricular Contractility during Machine Perfusion of the Donor Heart. J Heart Lung Transplant 2011. [DOI: 10.1016/j.healun.2011.01.602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Zhang JX, Xiang B, He Q, Seidel J, Zeches RJ, Yu P, Yang SY, Wang CH, Chu YH, Martin LW, Minor AM, Ramesh R. Large field-induced strains in a lead-free piezoelectric material. NATURE NANOTECHNOLOGY 2011; 6:98-102. [PMID: 21240285 DOI: 10.1038/nnano.2010.265] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 11/30/2010] [Indexed: 05/30/2023]
Abstract
Piezoelectric materials exhibit a mechanical response to electrical inputs, as well as an electrical response to mechanical inputs, which makes them useful in sensors and actuators. Lead-based piezoelectrics demonstrate a large mechanical response, but they also pose a health risk. The ferroelectric BiFeO(3) is an attractive alternative because it is lead-free, and because strain can stabilize BiFeO(3) phases with a structure that resembles a morphotropic phase boundary. Here we report a reversible electric-field-induced strain of over 5% in BiFeO(3) films, together with a characterization of the origins of this effect. In situ transmission electron microscopy coupled with nanoscale electrical and mechanical probing shows that large strains result from moving the boundaries between tetragonal- and rhombohedral-like phases, which changes the phase stability of the mixture. These results demonstrate the potential of BiFeO(3) as a substitute for lead-based materials in future piezoelectric applications.
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Xiang B, Ye X, Feng K. Conceptual and preliminary engineering design of experimental helium loop for China HCCB TBM components test. FUSION ENGINEERING AND DESIGN 2010. [DOI: 10.1016/j.fusengdes.2010.08.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Feng K, Pan C, Zhang G, Luo T, Zhao Z, Chen Y, Ye X, Hu G, Wang P, Yuan T, Feng Y, Xiang B, Zhang L, Wang Q, Cao Q, Li Z, Wang F. Progress on solid breeder TBM at SWIP. FUSION ENGINEERING AND DESIGN 2010. [DOI: 10.1016/j.fusengdes.2010.08.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Zhang Y, Cong X, Shi L, Xiang B, Li YM, Ding QW, Ding C, Wu LL, Yu GY. Activation of transient receptor potential vanilloid subtype 1 increases secretion of the hypofunctional, transplanted submandibular gland. Am J Physiol Gastrointest Liver Physiol 2010; 299:G54-62. [PMID: 20360133 DOI: 10.1152/ajpgi.00528.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hyposecretion occurs in most patients early after submandibular gland autotransplantation for severe keratoconjunctivitis sicca. Endogenous transient receptor potential vanilloid subtype 1 (TRPV1) has been recently demonstrated in rabbit submandibular glands, and activation of TRPV1 by capsaicin increases secretion in isolated glands, but the TRPV1-mediated secretory mechanism remains to be elucidated. The purpose of this study was to verify whether activation of TRPV1 by capsaicin could improve the secretion of transplanted gland and its underlying mechanism. The salivary flow of the transplanted glands was significantly decreased, and the mRNA and protein levels of TRPV1 and aquaporin 5 (AQP5) were downregulated in the transplanted glands. Topical capsaicin cream increased secretion and upregulated levels of TRPV1 and AQP5 in transplanted glands. Moreover, in cultured submandibular gland cells, capsaicin increased the mRNA expression of AQP5 and led to redistribution of AQP5 from the cytoplasm to the plasma membrane via TRPV1 activation. Capsaicin enhanced the phosphorylation of extracellular signal-regulated kinase (ERK). Preincubation of cells with PD98059, an inhibitor of ERK kinase, suppressed the capsaicin-induced mRNA expression of AQP5. In summary, the capsaicin-induced secretory mechanism involved activation of TRPV1 and upregulation of AQP5 in an ERK-dependent manner and promoted the redistribution of AQP5 in submandibular gland cells. Activation of TRPV1 may provide a new therapeutic strategy to improve submandibular gland hypofunction.
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Qian Y, Meng J, Tang H, Yang G, Deng Y, Wei D, Xiang B, Xiao X. Different structural remodelling in atrial fibrillation with different types of mitral valvular diseases. Europace 2010; 12:371-7. [DOI: 10.1093/europace/eup438] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Li YM, Zhang Y, Shi L, Xiang B, Cong X, Zhang YY, Wu LL, Yu GY. Isoproterenol improves secretion of transplanted submandibular glands. J Dent Res 2009; 88:477-82. [PMID: 19493894 DOI: 10.1177/0022034509337114] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Autotransplantation of the submandibular gland is effective for severe keratoconjunctivitis sicca. However, most transplants show decreased secretion shortly after the operation, which leads to obstruction of Wharton's duct. The hypothesis that decreased catecholamine release due to denervation contributes to hypofunction in the early phase was tested in transplanted glands in rabbits. We found that salivary flow, expression of beta(1)- and beta(2)-adrenoceptor, and the maximum binding capacity were markedly decreased in the transplanted glands. Isoproterenol significantly reversed the decreased secretion, enhanced the expressions of beta(1)- and beta(2)-adrenoceptor, and ameliorated the atrophy of acinar cells. The contents of cAMP and phospho-ERK 1/2 were increased after isoproterenol treatment. These results indicate that lack of beta-adrenoceptor stimulation is involved in early dysfunction of the transplanted gland. Isoproterenol treatment moderates structural injury and improves secretory function in the transplanted submandibular gland through up-regulating beta(1)- and beta(2)-adrenoceptor expression and post-receptor signal transduction.
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Wang E, Xiang B, Olivares MG, Chung C, Arteaga CL. Transforming growth factor beta engages TACE/ADAM17 and ErbB3 to activate PI3K/Akt in HER2-overexpressing breast cancer and desensitizes cells to trastuzumab. Cancer Res 2009. [DOI: 10.1158/0008-5472.sabcs-35] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Abstract #35
TGFb signaling synergizes with HER2 in breast cancer progression. Exogenous TGFb or expression of an activated TGFb type I receptor (Alk5T204D) in MCF10A/HER2 and BT474 cells activated PI3K/Akt and enhanced survival and migration. In both cell types, TGFb stimulated P-EGFR and P-HER2 as well as the association of p85, the regulatory subunit of PI3K, with Y1289 P-ErbB3 which, in turn, activated PI3K/Akt. RNA interference of ErbB3 or treatment with pertuzumab, an antibody that blocks HER2-mediated activation of ErbB3, blocked TGFb-induced P-ErbB3, P-Akt, and cell motility. Treatment with TGFb or expression of Alk5TD increased protein levels of secreted TGFalpha, amphiregulin, and heregulin without a change in mRNA levels. The increase on secreted ErbB ligands without a change in mRNA levels suggested increased shedding of ErbB pro-ligands by tumor necrosis factor a-converting enzyme (TACE). Transfection of siRNA against human TACE but not control siRNA abrogated TGFb-stimulated ErbB receptor phosphorylation, P-Akt, and cell invasiveness. Transfection of full-length mouse TACE but not truncated TACE lacking the cytoplasmic domain reconstituted TGFb-induced ErbB phosphorylation in cells transfected with human TACE siRNA. TGF-b increased TACE phosphorylation in both serine and threonine as measured by P-Ser and P-Thr immunoblots of TACE pull downs. Incubation of TACE with Alk5TD in the presence of ATP in vitro resulted in both Ser and Thr phosphorylation in full-length but not truncated TACE. Further, addition of TGFb or expression of Alk5TD desensitized SKBR3 and BT474 cells to trastuzumab. Treatment with the type I TGFb receptor (Alk5) small molecule inhibitor LY2109761, the PI3K inhibitor LY294002, or siRNA against ErbB3 or TACE restored the inhibitory effect of trastuzumab. Finally, we generated an active Alk5 expression signature by selecting genes that were differentially expressed between BT474/Alk5TD and BT474/vector cells. Mapping of this signature to a previously published 295-breast tumor array (van de Vijver et al. and Chang et al.) revealed 90 of 271 genes in the Alk5TD signature with a >1.5-fold change from the median expression which correlated with HER2-positive and basal-like tumors and conferred a worse recurrence-free (RFS) and overall survival (OS) (RFS p=0.05, OS p=0.01). Hierarchical clustering analysis to an array data set reported by Harris et al. in 22 patients with HER2+ breast cancer treated with neoadjuvant trastuzumab and vinorelbine (Clin. Cancer Res. 2007) showed that the Alk5TD signature correlated with tumors that did not respond clinically. These data suggest that TGFb potentiates signaling downstream ErbB receptors via TACE, ErbB3, and PI3K, thus contributing to tumor progression and resistance to anti-HER2 therapies.
Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 35.
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Soci C, Zhang A, Xiang B, Dayeh SA, Aplin DPR, Park J, Bao XY, Lo YH, Wang D. ZnO nanowire UV photodetectors with high internal gain. NANO LETTERS 2007; 7:1003-9. [PMID: 17358092 DOI: 10.1021/nl070111x] [Citation(s) in RCA: 825] [Impact Index Per Article: 48.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
ZnO nanowire (NW) visible-blind UV photodetectors with internal photoconductive gain as high as G approximately 108 have been fabricated and characterized. The photoconduction mechanism in these devices has been elucidated by means of time-resolved measurements spanning a wide temporal domain, from 10-9 to 102 s, revealing the coexistence of fast (tau approximately 20 ns) and slow (tau approximately 10 s) components of the carrier relaxation dynamics. The extremely high photoconductive gain is attributed to the presence of oxygen-related hole-trap states at the NW surface, which prevents charge-carrier recombination and prolongs the photocarrier lifetime, as evidenced by the sensitivity of the photocurrrent to ambient conditions. Surprisingly, this mechanism appears to be effective even at the shortest time scale investigated of t < 1 ns. Despite the slow relaxation time, the extremely high internal gain of ZnO NW photodetectors results in gain-bandwidth products (GB) higher than approximately 10 GHz. The high gain and low power consumption of NW photodetectors promise a new generation of phototransistors for applications such as sensing, imaging, and intrachip optical interconnects.
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Wang J, Xiang B, Liu H, Gruwel M, Li G, Jackson M, Salerno T, Tomanek B, Deslauriers R, Tian G. A70. Simultaneous perfusion is not superior to antegrade perfusion during beating heart valve surgery. J Mol Cell Cardiol 2006. [DOI: 10.1016/j.yjmcc.2006.03.410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Wang J, Xiang B, Grewul M, Liu H, Li G, Jackson M, Tomanek B, Deslauriers R, Tian G. A71. Identification of scarred myocardium using first pass MRI and delayed enhancement MRI. J Mol Cell Cardiol 2006. [DOI: 10.1016/j.yjmcc.2006.03.411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Wang J, Xiang B, Liu H, Grewul M, Li G, Jackson M, Salerno T, Tomanek B, Deslauriers R, Tian G. A55. Empty-beating perfusion improves preservation of hypertrophied hearts for valve surgery. J Mol Cell Cardiol 2006. [DOI: 10.1016/j.yjmcc.2006.03.409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Kupriyanov VV, Xiang B, Sun J, Jilkina O. Adrenergic stimulation of Rb+ uptake in pig hearts in vivo assessed by87Rb MRS. Magn Reson Med 2005; 53:817-22. [PMID: 15799046 DOI: 10.1002/mrm.20416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
It was previously shown that the adrenergic agonist dobutamine stimulates Rb(+) uptake in isolated pig hearts. In the present work we examined whether dobutamine can increase Rb(+) uptake rate in vivo. Open-chest domestic pigs (N = 14) were used under general anesthesia. The surface coil was placed against the anterior left ventricular wall to obtain (87)Rb spectra using a spectrometer interfaced with the 7T, 30-cm horizontal bore magnet. RbCl was infused at the rate of 1.35 +/- 0.14 mmol/kg/hr without or with dobutamine (0.6 mg/kg/hr) over a 60-min period, and then the infusions were terminated. The rate constant (k x 10(3), from 13 +/- 2.4 to 36 +/- 12 min(-1)) and Rb(+) influx rate (from 2.5% to 4.8%/min) were increased by dobutamine despite lower plasma [Rb(+)] (0.59 +/- 0.16 vs. 0.84 +/- 0.24 mM in control), while the tissue/plasma Rb ratios were identical (38 +/- 9). Heart rate (HR) and systolic blood pressure (SBP) were increased from 106 +/- 9 to 161 +/- 15 bpm (+52%) and from 78 +/- 7 to 93 +/- 11 mmHg (+19%), respectively. The stimulation of Rb(+) uptake by dobutamine is consistent with the activation of Na(+)/K(+) ATPase previously observed in isolated hearts. However, the 50% increase in HR and the double coronary flow caused by the SBP increase and vasodilatation may also contribute to this effect.
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