The Experts below are selected from a list of 30078 Experts worldwide ranked by ideXlab platform
Dana E. Selley - One of the best experts on this subject based on the ideXlab platform.
-
17 cyclopropylmethyl 3 14β dihydroxy 4 5α epoxy 6β 4 pyridylcarboxamido morphinan nap modulating the mu opioid receptor in a biased fashion
ACS Chemical Neuroscience, 2016Co-Authors: Yan Zhang, Dwight A. Williams, Saheem A. Zaidi, Yunyun Yuan, Amanda Braithwaite, Edward J. Bilsky, William L. Dewey, Hamid I. Akbarali, John M. Streicher, Dana E. SelleyAbstract:Mounting evidence has suggested that G protein-coupled receptors can be stabilized in multiple conformations in response to distinct ligands, which exert discrete functions through selective activation of various downstream signaling events. In accordance with this concept, we report biased signaling of one C6-heterocyclic substituted naltrexamine derivative, namely, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) at the mu opioid receptor (MOR). NAP acted as a low efficacy MOR partial agonist in the G protein-mediated [35S]GTPγS binding assay, whereas it did not significantly induce calcium flux or β-arrestin2 recruitment. In contrast, it potently blocked MOR full agonist-induced β-arrestin2 recruitment and translocation. Additionally, NAP dose-dependently antagonized MOR full agonist-induced intracellular calcium flux and β-arrestin2 recruitment. Further results in an Isolated Organ bath preparation confirmed that NAP reversed the morphine-induced reduction in c...
-
17-Cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) Modulating the Mu Opioid Receptor in a Biased Fashion
2015Co-Authors: Yan Zhang, Dwight A. Williams, Saheem A. Zaidi, Yunyun Yuan, Amanda Braithwaite, Edward J. Bilsky, William L. Dewey, Hamid I. Akbarali, John M. Streicher, Dana E. SelleyAbstract:Mounting evidence has suggested that G protein-coupled receptors can be stabilized in multiple conformations in response to distinct ligands, which exert discrete functions through selective activation of various downstream signaling events. In accordance with this concept, we report biased signaling of one C6-heterocyclic substituted naltrexamine derivative, namely, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) at the mu opioid receptor (MOR). NAP acted as a low efficacy MOR partial agonist in the G protein-mediated [35S]GTPγS binding assay, whereas it did not significantly induce calcium flux or β-arrestin2 recruitment. In contrast, it potently blocked MOR full agonist-induced β-arrestin2 recruitment and translocation. Additionally, NAP dose-dependently antagonized MOR full agonist-induced intracellular calcium flux and β-arrestin2 recruitment. Further results in an Isolated Organ bath preparation confirmed that NAP reversed the morphine-induced reduction in colon motility. Ligand docking and dynamics simulation studies of NAP at the MOR provided more supporting evidence for biased signaling of NAP at an atomic level. Due to the fact that NAP is MOR selective and preferentially distributed peripherally upon systemic administration while β-arrestin2 is reportedly required for impairment of intestinal motility by morphine, biased antagonism of β-arrestin2 recruitment by NAP further supports its utility as a treatment for opioid-induced constipation
Michael L Nicholson - One of the best experts on this subject based on the ideXlab platform.
-
naked small interfering rna of caspase 3 in preservation solution and autologous blood perfusate protects Isolated ischemic porcine kidneys
Transplantation, 2011Co-Authors: Bin Yang, Sarah A Hosgood, Michael L NicholsonAbstract:Background. Ischemia-reperfusion injury (IRI) plays key roles in graft viability and posttransplantation function. Caspase-3 associated with apoptosis and inflammation is up-regulated by IRI. We propose that naked small interfering RNA (siRNA) targeting caspase-3 may prevent IRI and improve kidney preservation. Methods. Porcine kidneys were retrieved after 10-min warm ischemia and flushed with 500 mL hyperosmolar citrate. Caspase-3 siRNA was administered directly into the renal artery in hyperosmolar citrate solution (3 μg/ml) with the renal vein clamped and into autologous blood (0.15 μg/ml), both of which were stored for 24 hr on ice. The kidneys were reperfused with oxygenated autologous blood for 3 hr on an Isolated Organ perfusion system to assess renal function. Results. In the siRNA-treated group, the expression of 32-kDa caspase-3 precursor and 17-kDa active subunit was down-regulated by 30% and 56%, respectively, with 40% reduction in active caspase-3+ cells. Consequently, apoptotic cells in the renal cortex were significantly decreased by 47%, whereas inflammatory cells were only marginally reduced by 26%. Caspase-3 siRNA also doubled oxygen consumption and significantly neutralized perfusate pH. Renal blood flow was gradually increased from 5 min to 3 hr by caspase-3 siRNA and marginally improved at the end of 3-hr reperfusion by 45%. Conclusions. The administration of caspase-3 siRNA directly into the kidney and hemoperfusate during cold preservation improved IRI with reduced caspase-3 and apoptosis, and better renal oxygenation and acid-base homeostasis. This proof of principle experiment using a novel siRNA therapy in large animal Organs provides valuable data for human kidney transplantation.
-
a comparison of hypothermic machine perfusion versus static cold storage in an experimental model of renal ischemia reperfusion injury
Transplantation, 2010Co-Authors: Sarah A Hosgood, Bin Yang, Atul Bagul, Ismail H Mohamed, Michael L NicholsonAbstract:INTRODUCTION There is increasing support for the use of hypothermic machine perfusion (HMP) in an attempt to reduce preservation injury. However, experimental evidence is needed to further examine the effects of HMP on renal ischemia reperfusion injury. METHODS Porcine kidneys were subjected to 10 min of warm ischemia followed by 18 hr of static cold storage with hyperosomolar citrate (HOC), histidine-tryptophan-ketoglutarate (HTK), or University of Wisconsin (UW) solutions or 18 hr HMP with Kidney Perfusion Solution using the Lifeport perfusion system. Renal function, oxidative damage, and morphology were assessed during 3 hr of reperfusion with autologous blood using an Isolated Organ perfusion system. RESULTS During reperfusion, intrarenal resistance was significantly lower in the HMP group compared with HOC and UW (area under the curve; HMP 3.8+/-1.7, HOC 9.1+/-4.3, UW 7.7+/-2.2, HTK 5.6+/-1.9 mm Hg/min; P=0.006), and creatinine clearance was significantly higher compared with the UW group (area under the curve creatinine clearance; HMP 9.8+/-7.3, HOC 2.2+/-1.7, UW 1.8+/-1.0, HTK 2.1+/-1.8 mL/min/100 g; P=0.004). Tubular function was significantly improved in the HMP group (P<0.05); however, levels of lipid peroxidation were significantly higher (P=0.005). CONCLUSION HMP demonstrated a reduced level of preservation injury compared with the static techniques resulting in improved renal and tubular function and less tubular cell inflammation during reperfusion.
-
the effect of warm ischemic time on renal function and injury in the Isolated hemoperfused kidney
Transplantation, 2008Co-Authors: Simon J. F. Harper, Sarah A Hosgood, Bin Yang, Helen L Waller, Mark D Kay, Ines Goncalves, Michael L NicholsonAbstract:BACKGROUND: The precise effect of warm ischemia on renal allograft function remains unclear and leads to variable warm ischemic time (WIT) limits advocated by transplant programs. This study aims to investigate the relationship between WIT, renal ischemia reperfusion injury, and graft function using a hemoperfused kidney model. METHODS: Porcine kidneys were perfused with normothermic blood on an Isolated Organ perfusion system. Kidneys were divided into four groups (n=6) and subjected to 7, 15, 25, and 40 min WIT. Physiological parameters were measured throughout the 6 hr perfusion period. Serum, tissue, and urine samples were analyzed for histological and biochemical markers of ischemia reperfusion injury. RESULTS: Creatinine clearance, urine output, renal hemodynamics, and oxygen consumption deteriorated proportionally with increasing WIT. A significant increase in plasma carbonyl levels during perfusion was seen after 25 and 40 min WIT only. Plasma 8-isoprostane levels were higher after 40 min WIT (2.5+/-1.6) vs. 7, 15, and 25 min WIT (0.65+/-0.43, 0.25+/-0.12, and 0.62+/-0.21, respectively; P<0.05). A negative correlation was shown between urine output and plasma carbonyls (r=-0.415, P<0.05) and between 8-isoprostane levels and creatinine clearance (r=-0.649, P<0.005). Caspase-3 activity was significantly higher after 7 min WIT compared with the other groups, correlating positively with creatinine clearance, urine output, and renal blood flow. CONCLUSION: The Isolated Organ perfusion system successfully delineated a clear WIT-dependent variation in renal function which correlated accurately with oxidative injury markers. This model may represent a clinically applicable tool for assessing graft viability.
-
differential expression of cytoprotective and apoptotic genes in an ischaemia reperfusion Isolated Organ perfusion model of the transplanted kidney
Transplant International, 2007Co-Authors: Helen L Waller, Sarah A Hosgood, Simon J. F. Harper, Bin Yang, Atul Bagul, Mark D Kay, Monika Kaushik, G R Bicknell, Michael L NicholsonAbstract:Summary The optimal kidney preservation system and methods to ameliorate reperfusion injury are major factors in accomplishing successful graft function following transplantation. Ischaemia and reperfusion lead to cellular stress and the adaptive response may include the activation of genes involved in cellular protection and/or cell death by apoptosis. We investigated the expression of cytoprotective heme oxygenase-1 (HO-1), anti-apoptotic Bcl-2 and pro-apoptotic Bax after 6 h Isolated Organ perfusion in porcine kidneys that had been given 10 and 40 min warm ischaemic time. The level of HO-1 was shown to be significantly higher in the 10-min warm ischaemic group compared with 40-min group (0.90 ± 0.03 vs. 0.83 ± 0.03; P = 0.002). The levels of HO-1 showed a significant positive correlated with parameters of renal function, creatinine clearance, and renal blood flow and urine output (AUC; r = 0.8042, P = 0.03; r = 0.6028, P = 0.04; r = 0.6055, P = 0.04), demonstrating a possible protective role of this gene in this model of renal transplantation.
-
biomarkers of oxidative damage to predict ischaemia reperfusion injury in an Isolated Organ perfusion model of the transplanted kidney
Free Radical Research, 2006Co-Authors: Helen L Waller, Sarah A Hosgood, Simon J. F. Harper, Bin Yang, Atul Bagul, Mark D Kay, Monika Kaushik, Michael L NicholsonAbstract:Ischaemia-reperfusion (IR) injury is known to be a risk factor influencing both short and long-term graft function following transplantation. The pathophysiology of IR injury is suggested to involve elevated reactive oxygen species production resulting in oxidative damaged cellular macromolecules. The objective of this study was to evaluate oxidative damage following IR using an Isolated Organ perfusion model of the transplanted kidney, in order to determine a simple, preferably non-invasive biomarker for IR injury. Porcine kidneys were retrieved with 10 or 40 min warm ischaemic (WI) time and haemoperfused for 6 h on an Isolated Organ perfusion machine. ELISA was used to detect carbonyls, 8-isporostane and 8-hydroxy-2'-deoxyguanosine, representing protein, lipid and DNA damage respectively in pre and post reperfusion samples of plasma, urine and biopsy material. Plasma carbonyl and 8-isporostane and were significantly increased in the 40 min group compared to pre-perfusion (0.96 +/- 0.10 vs. 0.62 +/- 0.06, P < 0.001 and 1.57(1.28-4.9) vs. 0.36(0.09-0.59), P < 0.05). The levels also correlated with creatinine clearance used to determine renal function (r = - 0.6150, P < 0.01 and r = - 0.7727, P < 0.01). The results of this study suggest both plasma carbonyl and 8-isporostane to be reliable biomarkers to predict the level IR injury.
Yan Zhang - One of the best experts on this subject based on the ideXlab platform.
-
17 cyclopropylmethyl 3 14β dihydroxy 4 5α epoxy 6β 4 pyridylcarboxamido morphinan nap modulating the mu opioid receptor in a biased fashion
ACS Chemical Neuroscience, 2016Co-Authors: Yan Zhang, Dwight A. Williams, Saheem A. Zaidi, Yunyun Yuan, Amanda Braithwaite, Edward J. Bilsky, William L. Dewey, Hamid I. Akbarali, John M. Streicher, Dana E. SelleyAbstract:Mounting evidence has suggested that G protein-coupled receptors can be stabilized in multiple conformations in response to distinct ligands, which exert discrete functions through selective activation of various downstream signaling events. In accordance with this concept, we report biased signaling of one C6-heterocyclic substituted naltrexamine derivative, namely, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) at the mu opioid receptor (MOR). NAP acted as a low efficacy MOR partial agonist in the G protein-mediated [35S]GTPγS binding assay, whereas it did not significantly induce calcium flux or β-arrestin2 recruitment. In contrast, it potently blocked MOR full agonist-induced β-arrestin2 recruitment and translocation. Additionally, NAP dose-dependently antagonized MOR full agonist-induced intracellular calcium flux and β-arrestin2 recruitment. Further results in an Isolated Organ bath preparation confirmed that NAP reversed the morphine-induced reduction in c...
-
17-Cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) Modulating the Mu Opioid Receptor in a Biased Fashion
2015Co-Authors: Yan Zhang, Dwight A. Williams, Saheem A. Zaidi, Yunyun Yuan, Amanda Braithwaite, Edward J. Bilsky, William L. Dewey, Hamid I. Akbarali, John M. Streicher, Dana E. SelleyAbstract:Mounting evidence has suggested that G protein-coupled receptors can be stabilized in multiple conformations in response to distinct ligands, which exert discrete functions through selective activation of various downstream signaling events. In accordance with this concept, we report biased signaling of one C6-heterocyclic substituted naltrexamine derivative, namely, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) at the mu opioid receptor (MOR). NAP acted as a low efficacy MOR partial agonist in the G protein-mediated [35S]GTPγS binding assay, whereas it did not significantly induce calcium flux or β-arrestin2 recruitment. In contrast, it potently blocked MOR full agonist-induced β-arrestin2 recruitment and translocation. Additionally, NAP dose-dependently antagonized MOR full agonist-induced intracellular calcium flux and β-arrestin2 recruitment. Further results in an Isolated Organ bath preparation confirmed that NAP reversed the morphine-induced reduction in colon motility. Ligand docking and dynamics simulation studies of NAP at the MOR provided more supporting evidence for biased signaling of NAP at an atomic level. Due to the fact that NAP is MOR selective and preferentially distributed peripherally upon systemic administration while β-arrestin2 is reportedly required for impairment of intestinal motility by morphine, biased antagonism of β-arrestin2 recruitment by NAP further supports its utility as a treatment for opioid-induced constipation
William L. Dewey - One of the best experts on this subject based on the ideXlab platform.
-
17 cyclopropylmethyl 3 14β dihydroxy 4 5α epoxy 6β 4 pyridylcarboxamido morphinan nap modulating the mu opioid receptor in a biased fashion
ACS Chemical Neuroscience, 2016Co-Authors: Yan Zhang, Dwight A. Williams, Saheem A. Zaidi, Yunyun Yuan, Amanda Braithwaite, Edward J. Bilsky, William L. Dewey, Hamid I. Akbarali, John M. Streicher, Dana E. SelleyAbstract:Mounting evidence has suggested that G protein-coupled receptors can be stabilized in multiple conformations in response to distinct ligands, which exert discrete functions through selective activation of various downstream signaling events. In accordance with this concept, we report biased signaling of one C6-heterocyclic substituted naltrexamine derivative, namely, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) at the mu opioid receptor (MOR). NAP acted as a low efficacy MOR partial agonist in the G protein-mediated [35S]GTPγS binding assay, whereas it did not significantly induce calcium flux or β-arrestin2 recruitment. In contrast, it potently blocked MOR full agonist-induced β-arrestin2 recruitment and translocation. Additionally, NAP dose-dependently antagonized MOR full agonist-induced intracellular calcium flux and β-arrestin2 recruitment. Further results in an Isolated Organ bath preparation confirmed that NAP reversed the morphine-induced reduction in c...
-
17-Cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) Modulating the Mu Opioid Receptor in a Biased Fashion
2015Co-Authors: Yan Zhang, Dwight A. Williams, Saheem A. Zaidi, Yunyun Yuan, Amanda Braithwaite, Edward J. Bilsky, William L. Dewey, Hamid I. Akbarali, John M. Streicher, Dana E. SelleyAbstract:Mounting evidence has suggested that G protein-coupled receptors can be stabilized in multiple conformations in response to distinct ligands, which exert discrete functions through selective activation of various downstream signaling events. In accordance with this concept, we report biased signaling of one C6-heterocyclic substituted naltrexamine derivative, namely, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) at the mu opioid receptor (MOR). NAP acted as a low efficacy MOR partial agonist in the G protein-mediated [35S]GTPγS binding assay, whereas it did not significantly induce calcium flux or β-arrestin2 recruitment. In contrast, it potently blocked MOR full agonist-induced β-arrestin2 recruitment and translocation. Additionally, NAP dose-dependently antagonized MOR full agonist-induced intracellular calcium flux and β-arrestin2 recruitment. Further results in an Isolated Organ bath preparation confirmed that NAP reversed the morphine-induced reduction in colon motility. Ligand docking and dynamics simulation studies of NAP at the MOR provided more supporting evidence for biased signaling of NAP at an atomic level. Due to the fact that NAP is MOR selective and preferentially distributed peripherally upon systemic administration while β-arrestin2 is reportedly required for impairment of intestinal motility by morphine, biased antagonism of β-arrestin2 recruitment by NAP further supports its utility as a treatment for opioid-induced constipation
Dwight A. Williams - One of the best experts on this subject based on the ideXlab platform.
-
17 cyclopropylmethyl 3 14β dihydroxy 4 5α epoxy 6β 4 pyridylcarboxamido morphinan nap modulating the mu opioid receptor in a biased fashion
ACS Chemical Neuroscience, 2016Co-Authors: Yan Zhang, Dwight A. Williams, Saheem A. Zaidi, Yunyun Yuan, Amanda Braithwaite, Edward J. Bilsky, William L. Dewey, Hamid I. Akbarali, John M. Streicher, Dana E. SelleyAbstract:Mounting evidence has suggested that G protein-coupled receptors can be stabilized in multiple conformations in response to distinct ligands, which exert discrete functions through selective activation of various downstream signaling events. In accordance with this concept, we report biased signaling of one C6-heterocyclic substituted naltrexamine derivative, namely, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) at the mu opioid receptor (MOR). NAP acted as a low efficacy MOR partial agonist in the G protein-mediated [35S]GTPγS binding assay, whereas it did not significantly induce calcium flux or β-arrestin2 recruitment. In contrast, it potently blocked MOR full agonist-induced β-arrestin2 recruitment and translocation. Additionally, NAP dose-dependently antagonized MOR full agonist-induced intracellular calcium flux and β-arrestin2 recruitment. Further results in an Isolated Organ bath preparation confirmed that NAP reversed the morphine-induced reduction in c...
-
17-Cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) Modulating the Mu Opioid Receptor in a Biased Fashion
2015Co-Authors: Yan Zhang, Dwight A. Williams, Saheem A. Zaidi, Yunyun Yuan, Amanda Braithwaite, Edward J. Bilsky, William L. Dewey, Hamid I. Akbarali, John M. Streicher, Dana E. SelleyAbstract:Mounting evidence has suggested that G protein-coupled receptors can be stabilized in multiple conformations in response to distinct ligands, which exert discrete functions through selective activation of various downstream signaling events. In accordance with this concept, we report biased signaling of one C6-heterocyclic substituted naltrexamine derivative, namely, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-(4′-pyridylcarboxamido)morphinan (NAP) at the mu opioid receptor (MOR). NAP acted as a low efficacy MOR partial agonist in the G protein-mediated [35S]GTPγS binding assay, whereas it did not significantly induce calcium flux or β-arrestin2 recruitment. In contrast, it potently blocked MOR full agonist-induced β-arrestin2 recruitment and translocation. Additionally, NAP dose-dependently antagonized MOR full agonist-induced intracellular calcium flux and β-arrestin2 recruitment. Further results in an Isolated Organ bath preparation confirmed that NAP reversed the morphine-induced reduction in colon motility. Ligand docking and dynamics simulation studies of NAP at the MOR provided more supporting evidence for biased signaling of NAP at an atomic level. Due to the fact that NAP is MOR selective and preferentially distributed peripherally upon systemic administration while β-arrestin2 is reportedly required for impairment of intestinal motility by morphine, biased antagonism of β-arrestin2 recruitment by NAP further supports its utility as a treatment for opioid-induced constipation
